ApJ - 3343

• (2025). CHIME/FRB outriggers: Design overview. ApJ, 993(1), 55. (www)

  @article{ , abstract = {The Canadian Hydrogen Intensity Mapping Experiment (CHIME) has emerged as the world’s premier facility for studying fast radio bursts (FRBs) through its fast transient search backend CHIME/FRB. The CHIME/FRB Outriggers project will augment this high detection rate of 2–3 FRBs per day with the ability to precisely localize them using very long baseline interferometry (VLBI). Using three strategically located stations in North America and deploying recently developed synoptic VLBI observing techniques, the Outriggers will provide ∼50 mas localization precision for the majority of detected FRBs. This paper presents an overview of the design and implementation of the Outriggers, covering their geographic distribution, structural design, and observational capabilities. We detail the scientific objectives driving the project, including the characterization of FRB populations, host galaxy demographics, and the use of FRBs as cosmological probes. We also discuss the calibration strategies available to mitigate ionospheric and instrumental effects, ensuring high-precision localization. With two stations currently in science operations, and the third in commissioning, the CHIME/FRB Outriggers project is poised to become a cornerstone of the FRB field, offering unprecedented insights into this enigmatic cosmic phenomenon.}, archive = {J_ApJ}, author = {The CHIME/FRB Collaboration and Mandana Amiri and Bridget C. Andersen and Shion Andrew and Kevin Bandura and Mohit Bhardwaj and Kalyani Bhopi and Vadym Bidula and P. J. Boyle and Charanjot Brar and Mark Carlson and Tomas Cassanelli and Alyssa Cassity and Shami Chatterjee and Jean-François Cliche and Alice P. Curtin and Rachel Darlinger and David R. DeBoer and Matt Dobbs and Fengqiu Adam Dong and Gwendolyn Eadie and Emmanuel Fonseca and B. M. Gaensler and Nina Gusinskaia and Mark Halpern and Ian Hendricksen and Jason Hessels and Ronniy C. Joseph and Jane Kaczmarek and Victoria M. Kaspi and Kholoud Khairy and T. L. Landecker and Adam E. Lanman and Albert Wai Kit Lau and Mattias Lazda and Calvin Leung and Robert A. Main and Kiyoshi W. Masui and Ryan Mckinven and Juan Mena-Parra and Bradley W. Meyers and Daniele Michilli and Nikola Milutinovic and Kenzie Nimmo and Gavin Noble and Ayush Pandhi and Aaron B. Pearlman and Jeffrey B. Peterson and Emily Petroff and Ziggy Pleunis and Alexander W. Pollak and Masoud Rafiei-Ravandi and Andre Renard and Mawson W. Sammons and Ketan R. Sand and Pranav Sanghavi and Paul Scholz and Vishwangi Shah and Kaitlyn Shin and Seth R. Siegel and Andrew Siemion and Jonathan L. Sievers and Kendrick Smith and David Spear and Ingrid Stairs and Keith Vanderlinde and Haochen Wang and Jacob P. Willis and Tarik J. Zegmott}, doi = {10.3847/1538-4357/adfdcc}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {55}, shortjournal = {The Astrophys. J.}, title = {CHIME/FRB outriggers: Design overview}, volume = {993}, year = {2025}, }
• (2025). The cygnus X-1 puzzle: Implications of X-ray polarization measurements in the soft and hard states on the properties of the accretion flow and the emission mechanisms. ApJ, 993(1), 54. (www)

  @article{ , abstract = {In this paper, we summarize key observational constraints of the accretion flow on the black hole X-ray Binary Cygnus X-1 (Cyg X-1). The discussion highlights the flows of energy close to the black hole and the importance of the distance range from which the radiating zone draws its energy. For the hard state, we examine compact and extended corona models. We find that compact corona models are energetically favored, but extended models cannot be fully excluded. We discuss the high linear polarization of the Cyg X-1 X-rays in the soft and hard states parallel to the direction of the radio jet. We propose the presence of a pair layer enveloping the accretion disk moving at approximately half the speed of light away from the disk for both the soft and the hard state. In the soft state, the pairs cool to the Compton temperature of the disk emission. In the hard state, the pairs acquire thermal and bulk motion allowing them to Comptonize the emission to produce the observed power law emission. In both emission states, the bulk motion away from the disk leads to a net polarization parallel to the radio jet. We emphasize that the geometry of the accretion flow in the hard state is still not well constrained, and that observed spectral (including the relativistically broadened Fe K- α line) and spectro-polarimetric signatures depend strongly on the plasma processes responsible for energy dissipation in the plasma.}, archive = {J_ApJ}, author = {Henric Krawczynski and Kun Hu}, doi = {10.3847/1538-4357/adfddf}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {54}, shortjournal = {The Astrophys. J.}, title = {The cygnus X-1 puzzle: Implications of X-ray polarization measurements in the soft and hard states on the properties of the accretion flow and the emission mechanisms}, volume = {993}, year = {2025}, }
• (2025). Do white dwarfs sample water-rich planetary material?. ApJ, 993(1), 53. (www)

  @article{ , abstract = {Polluted white dwarfs offer a unique way to directly probe the compositions of exoplanetary bodies. We examine the water content of accreted material using the oxygen abundances of 51 highly polluted white dwarfs. Within this sample, we present new abundances for three H-dominated atmosphere white dwarfs that showed promise for accreting water-rich material. Throughout, we explore the impact of the observed phase and lifetime of accretion disks on the inferred elemental abundances of the parent bodies that pollute each white dwarf. Our results indicate that white dwarfs sample a range of dry to water-rich material, with median uncertainties in water mass fractions of ≈15%. Among the He-dominated white dwarfs, 35/39 water abundances are consistent with corresponding H abundances. While for any individual white dwarf it may be ambiguous as to whether or not water is present in the accreted parent body, when considered as a population, the prevalence of water-rich bodies is statistically robust. The population as a whole has a median water mass fraction of ≈25%, and enforcing chondritic parent body compositions, we find that 31/51 WDs are likely to have nonzero water concentrations. This conclusion is different from a similar previous analysis of white dwarf pollution and we discuss reasons why this might be the case. Pollution in H-dominated white dwarfs continues to be more water-poor than in their He-dominated cousins, although the sample size of H-dominated white dwarfs remains small and the two samples still suffer a disjunction in the range of host star temperatures being probed.}, archive = {J_ApJ}, author = {Isabella L. Trierweiler and Carl Melis and Érika Le Bourdais and Patrick Dufour and Alycia J. Weinberger and Boris T. Gänsicke and Nicola Gentile-Fusillo and Siyi Xu and Jay Farihi and Andrew Swan and Malena Rice and Edward D. Young}, doi = {10.3847/1538-4357/ae003d}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {53}, shortjournal = {The Astrophys. J.}, title = {Do white dwarfs sample water-rich planetary material?}, volume = {993}, year = {2025}, }
• (2025). FOGGIE. x. characterizing the small-scale structure of the circumgalactic medium and its imprint on observables. ApJ, 993(1), 52. (www)

  @article{ , abstract = {One of the main unknowns in galaxy evolution is how gas flows into and out of galaxies in the circumgalactic medium (CGM). Studies observing the CGM in absorption using multiple or extended background objects suggest a high degree of variation on relatively small (≲1 kpc) spatial scales. Similarly, high-resolution simulations generally exhibit small-scale substructure in the gas around galaxies. We examine the small-scale structure of the z = 1 CGM using simulations from the Figuring Out Gas and Galaxies in Enzo (FOGGIE) project. We select gaseous substructures (“clumps”) by their local overdensity and investigate their physical properties, including temperature, metallicity, and kinematics with respect to the galaxy and the nearby surroundings. FOGGIE resolves clumps down to sphericalized radii R ∼ 0.25 kpc at z = 1. The distribution of clumps peaks at ∼10 5 M ⊙ and 10 4 K, consistent with relatively condensed, cool gas with a slight preference for inflow-like velocities. Many clumps show internal temperature and density variations, and thus internally varying ionization levels for key diagnostic ions such as H i , Mg ii , and O vi . The average metallicity in clumps is about a factor 1.5–2× lower in metallicity than nearby gas, suggesting that the metals are not well mixed between structured and diffuse CGMs, which may have implications for observational metallicity estimations of dense CGM clouds. We estimate the survivability of CGM clumps and find that structures larger than 0.5 kpc are generally long-lived. Finally, we qualitatively compare the simulated cloud properties to Milky Way high-velocity clouds.}, archive = {J_ApJ}, author = {Ramona Augustin and Jason Tumlinson and Molly S. Peeples and Brian W. O’Shea and Britton D. Smith and Cassandra Lochhaas and Anna C. Wright and Ayan Acharyya and Jessica K. Werk and Nicolas Lehner and Lauren Corlies and Raymond C. Simons and J. Christopher Howk and John M. O’Meara}, doi = {10.3847/1538-4357/ae0462}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {52}, shortjournal = {The Astrophys. J.}, title = {FOGGIE. x. characterizing the small-scale structure of the circumgalactic medium and its imprint on observables}, volume = {993}, year = {2025}, }
• (2025). RapidGBM: An efficient tool for fermi-GBM visibility checking and data analysis with a case study of EP240617a. ApJ, 993(1), 51. (www)

  @article{ , abstract = {We have developed a lightweight tool, RapidGBM , featuring a web-based interface and capabilities of rapid calculation of Fermi Gamma-ray Burst Monitor (GBM) visibilities and performance of basic data analysis. It has two key features: (1) it can immediately check the visibility of Fermi-GBM for new transients, and (2) it can check the light curve and perform spectral analysis after the hourly Time-Tagged Event data are released. The visibility check and the response matrix generation required for spectral analysis can be achieved through the historical pointing file after the orbit calculation, even when the real-time pointing file is not yet available. As a case study, we apply the tool to EP240617a, an X-ray transient triggered by Einstein Probe (EP). We demonstrate the workflow of visibility checking, data processing, and spectral analysis for this event. The results suggest that EP240617a can be classified as an X-ray-rich gamma-ray burst and confirm the feasibility of using historical pointing files for rapid analysis. Further, we discuss possible physical interpretations of such events, including implications for jet launching and progenitor scenarios. Therefore, RapidGBM is expected to assist EP transient advocates, Space-based multiband astronomical Variable Objects Monitor burst advocates, and other members of the community in cross checking high-energy transients. Based on prompt emission parameter relations (e.g., E p – E γ ,iso ), it can also help identify peculiar GRBs (e.g., long-short burst, magnetar giant flare, etc.) and provide useful references (e.g., more accurate T 0 ) for scheduling follow-up observations.}, archive = {J_ApJ}, author = {Yun Wang and Jia Ren and Lu-Yao Jiang and Hao Zhou and Yi-Han Iris Yin and Yi-Fang Liang and Zhi-Ping Jin and Yi-Zhong Fan and Da-Ming Wei and Wei Chen and Hui Sun and Jing-Wei Hu and Dong-Yue Li and Jun Yang and Wen-Da Zhang and Yuan Liu and Wei-Min Yuan and Xue-Feng Wu}, doi = {10.3847/1538-4357/ae04e8}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {51}, shortjournal = {The Astrophys. J.}, title = {RapidGBM: An efficient tool for fermi-GBM visibility checking and data analysis with a case study of EP240617a}, volume = {993}, year = {2025}, }
• (2025). The relation between the optical variability timescale, magnetic field of jets, and black hole spin in active galactic nuclei. ApJ, 993(1), 50. (www)

  @article{ , abstract = {We investigate the relationship among the jet magnetic field, black hole spin, black hole mass, Eddington ratio, and optical variability timescales in jetted active galactic nuclei (AGNs). By fitting a damped random walk (DRW) model to the g -band light curves, we obtain the characteristic variability timescale ( τ DRW ) for 41 jetted AGNs with precise supermassive black hole (SMBH) mass measurements. Our main results are as follows: (i) Our analysis reveals a significant correlation between the jet magnetic field ( B 1 pc ), black hole spin ( j ) and the characteristic variability timescale within our sample. These findings suggest that the optical variability of jetted AGNs is influenced by the jet magnetic field and black hole spin. Furthermore, the characteristic variability timescale aligns with the electron escape timescale, as evidenced by the relationship between the characteristic variability timescale and jet magnetic field ( {\tau }_{\mathrm{DRW}}\propto {B}_{1\,\mathrm{pc}}^{0.76\pm 0.22} ). (ii) We confirm a significant correlation between the characteristic variability timescale and SMBH mass, expressed as: \mathrm{log}{\tau }_{\mathrm{DRW}}=0.52(\pm 0.21)\mathrm{log}{M}_{\mathrm{BH}}/{M}_{\odot }-3.12(\pm 1.90) , with an intrinsic scatter of 0.08 dex. The slope of this relationship is consistent with that between the thermal timescale and black hole mass. Our results support the hypothesis that magnetorotational instability fluctuations drive the intrinsic variability observed in the light curves emitted by the AGN's accretion disk.}, archive = {J_ApJ}, author = {Yongyun Chen and Qiusheng Gu and Junhui Fan and Dingrong Xiong and Xiaoling Yu and Xiaotong Guo and Nan Ding and Ting-Feng Yi}, doi = {10.3847/1538-4357/ae08ac}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {50}, shortjournal = {The Astrophys. J.}, title = {The relation between the optical variability timescale, magnetic field of jets, and black hole spin in active galactic nuclei}, volume = {993}, year = {2025}, }
• (2025). Cosmic dust as a prerequisite for the formation of complex organic molecules in space?. ApJ, 993(1), 49. (www)

  @article{ , abstract = {In cold, dense astrophysical environments dust grains are mixed with molecular ices. Chemistry in those dust/ice mixtures is determined by diffusion and reaction of molecules and radicals. However, investigations of diffusion of astrophysically relevant radicals and molecules across the surface and through the pores of cosmic dust grains and of surface reactions consequent to such diffusion are largely uncharted territory. This paper presents results of a study of a solid-state reaction of two molecular species, CO 2 and NH 3 , separated by a layer of porous silicate grain aggregates, analogues of cosmic dust. The experiments demonstrate that the presence of the dust layer was necessary for a pure thermal CO 2 + 2NH 3 reaction to proceed, leading to the formation of ammonium carbamate (NH 4 + NH 2 COO − ), an ionic solid containing a complex organic moiety of prebiotic interest recently detected in a protoplanetary disk. This result speaks for (i) efficient diffusion of molecules on/within cosmic dust, (ii) an underestimated role for surface catalysis in the astrochemistry of cosmic dust, and (iii) potentially efficient dust-promoted chemistry in warm cosmic environments, such as protostellar envelopes and protoplanetary disks.}, archive = {J_ApJ}, author = {Alexey Potapov and Kilian Pollok and Falko Langenhorst and Martin McCoustra and Robin T. Garrod}, doi = {10.3847/1538-4357/ae08ae}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {49}, shortjournal = {The Astrophys. J.}, title = {Cosmic dust as a prerequisite for the formation of complex organic molecules in space?}, volume = {993}, year = {2025}, }
• (2025). Fundamental understanding of magnetic reconnection via spiral CT scan. v. ion demagnetization, electron demagnetization, and hall effect. ApJ, 993(1), 48. (www)

  @article{ , abstract = {For the first time, we reveal the distribution of ion demagnetization, electron demagnetization, and Hall effect around a reconnection X-line by using the spiral CT scan technique, which is a novel technique analogous to that in the hospital. This X-line was detected by the Magnetospheric Multiscale mission and has been widely believed to host a non-guide-field reconnection. With the help of such an advanced technique, we find that: (1) the ion demagnetization is prominent everywhere at scale <1 d i , with a clear enhancement corresponding to the out-of-plane electron jet near the X-point; (2) the Hall electric field is large in both the magnetosheath-side and magnetosphere-side inflow regions, but is small at the current sheet center; (3) the electron demagnetization is strong in the magnetosheath-side inflow region and at the out-of-plane electron jet, but is weak in the magnetosphere-side inflow region and at the separatrix; (4) there is a good correlation between the ion demagnetization and Hall electric field at scale 0.25 d i < Δ < 1 d i , indicating that at such scale the Hall electric field is responsible for the breaking of the ion frozen-in law; (5) there is a good correlation between the electron demagnetization and whistler-wave power around the whole X-line, meaning that whistler waves lead to the electron demagnetization; (7) apparently, there is no correlation between the electron demagnetization and Hall electric field, so that the Hall effect does not contribute to electron demagnetization; and (8) at scale <0.25 d i , the ion demagnetization should be attributed to other effects, rather than the Hall electric field. The exact mechanism for whistler waves to cause electron demagnetization is the anomalous resistivity. All these results clearly demonstrate that magnetic reconnection is triggered (electron demagnetization) by whistler waves and is developed (ion demagnetization) by Hall effects in space.}, archive = {J_ApJ}, author = {H. S. Fu and Z. Wang and J. B. Cao}, doi = {10.3847/1538-4357/ae0ffc}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {48}, shortjournal = {The Astrophys. J.}, title = {Fundamental understanding of magnetic reconnection via spiral CT scan. v. ion demagnetization, electron demagnetization, and hall effect}, volume = {993}, year = {2025}, }
• (2025). Electronic spectroscopy of c60+ and its analogs C60H2O+, C60H+, C60D+, and C60Mg+. ApJ, 993(1), 47. (www)

  @article{ , abstract = {The fullerenes C 60 and C 70 have been detected in various interstellar environments, and the cation {{{\rm{C}}}_{60}}^{+} has been identified as a carrier of at least four of the diffuse interstellar bands (DIBs). Based on the presence of fullerenes in space, it is plausible that certain fullerene analogs are abundant in interstellar environments as well. In this context, we present the first electronic laboratory spectra of the analogs C 60 H 2 O + , C 60 H + , C 60 D + , and C 60 Mg + . Furthermore, the electronic {{{\rm{C}}}_{60}}^{+} spectrum is remeasured and assignments of the observed transitions are proposed. In the spectrum of C 60 H 2 O + , several distinct absorption features could be detected between 10,300 and 10,800 cm −1 , whereas the analogs C 60 H + , C 60 D + , and C 60 Mg + show a broad absorption in the visible region between 17,000 and 25,000 cm −1 . None of the detected absorption features in these analogs of {{{\rm{C}}}_{60}}^{+} could be assigned to DIBs.}, archive = {J_ApJ}, author = {Lisa Ganner and Gabriel Schöpfer and Alexander Ebenbichler and Stefan Bergmeister and Milan Ončák and Helgi Rafn Hrodmarsson and Elisabeth Gruber}, doi = {10.3847/1538-4357/adfd50}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {47}, shortjournal = {The Astrophys. J.}, title = {Electronic spectroscopy of c60+ and its analogs C60H2O+, C60H+, C60D+, and C60Mg+}, volume = {993}, year = {2025}, }
• (2025). The optical to X-ray luminosity and spectrum of supernova wind breakouts. ApJ, 993(1), 46. (www)

  @article{ , abstract = {Observations indicate that an optically thick circumstellar medium (CSM) at radii of 10 14 –10 15 cm around Type II core-collapse supernova (SN) progenitors is common (and may be present in other types of massive star explosions). The breakout of the SN radiation-mediated shock (RMS) through such a CSM leads to the formation of a collisionless shock (CLS). We analyze the evolution of the shock structure and associated radiation field during and after the RMS–CLS transition for nonrelativistic shock breakout velocities ( v bo = 10 9 v 9 cm s −1 < 0.1 c ) through a hydrogen-rich CSM “wind” density profile, ρ ∝ r −2 , with breakout radius R bo = 10 14 R 14 cm, much larger than the progenitor radius. An analytic description of the key properties of the emitted optical to X-ray radiation is provided, supported by numeric radiation hydrodynamics calculations self-consistently describing the time-dependent spatial distribution of the plasma and radiation, governed by bremsstrahlung emission/absorption and inelastic Compton scattering. The characteristic energy of the photons carrying most of the luminosity, \approx 1{0}^{43}\,{R}_{14}\,{v}_{9}^{2}\, erg s −1 , shifts from UV to X-rays, reaching 1 keV as the shock reaches ≈3 R bo , in ≈3 R 14 / v 9 days. The X-ray signal is not suppressed by propagation through the upstream wind, and its absence may suggest that the dense CSM does not extend much beyond R bo . Our results provide the basis for a quantitative calculation of the high-energy γ -ray and neutrino emission that is expected from particles accelerated at the CLS, and will allow using data from upcoming surveys that will systematically detect large numbers of young SNe, particularly ULTRASAT, to infer the preexplosion mass-loss history of the SN progenitor population.}, archive = {J_ApJ}, author = {Tal Wasserman and Nir Sapir and Peter Szabo and Eli Waxman}, doi = {10.3847/1538-4357/adfecc}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {46}, shortjournal = {The Astrophys. J.}, title = {The optical to X-ray luminosity and spectrum of supernova wind breakouts}, volume = {993}, year = {2025}, }
• (2025). Optical spectroscopy reveals hidden neutron-capture elemental abundance differences among APOGEE-identified chemical doppelgängers*. ApJ, 993(1), 45. (www)

  @article{ , abstract = {Grouping stars by chemical similarity has the potential to reveal the Milky Way’s evolutionary history. The APOGEE stellar spectroscopic survey has the resolution and sensitivity for this task. However, APOGEE lacks access to strong lines of neutron-capture elements ( Z > 28), which have nucleosynthetic origins that are distinct from those of the lighter elements. We assess whether APOGEE abundances are sufficient for selecting chemically similar disk stars by identifying 25 pairs of chemical “doppelgängers” in APOGEE DR17 and following them up with the Tull spectrograph, an optical, R ∼ 60,000 echelle on the McDonald Observatory 2.7 m telescope. Line-by-line differential analyses of pairs’ optical spectra reveal neutron-capture (Y, Zr, Ba, La, Ce, Nd, and Eu) elemental abundance differences of Δ[X/Fe] ∼ 0.020 ± 0.015 to 0.380 ± 0.15 dex (4%–140%), and up to 0.05 dex (12%) on average, a factor of 1–2 times higher than intracluster pairs. This is despite the pairs sharing nearly identical APOGEE-reported abundances and [C/N] ratios, a tracer of giant-star age. This work illustrates that even when APOGEE abundances derived from spectra with a signal-to-noise ratio > 300 are available, optically measured neutron-capture element abundances contain critical information about composition similarity. These results hold implications for the chemical dimensionality of the disk, mixing within the interstellar medium, and chemical tagging with the neutron-capture elements.}, archive = {J_ApJ}, author = {Catherine Manea and Melissa Ness and Keith Hawkins and Greg Zeimann and David W. Hogg and Carrie Filion and Emily J. Griffith and Kathryn Johnston and Andrew Casey and Zoe Hackshaw and Tyler Nelson and Micah Marks}, doi = {10.3847/1538-4357/adff75}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {45}, shortjournal = {The Astrophys. J.}, title = {Optical spectroscopy reveals hidden neutron-capture elemental abundance differences among APOGEE-identified chemical doppelgängers*}, volume = {993}, year = {2025}, }
• (2025). Highly ionized gas in the zone of avoidance: Using the CIViL⋆ survey to pinpoint physical conditions of gaseous halos. ApJ, 993(1), 44. (www)

  @article{ , abstract = {This paper investigates the physical conditions of the circumgalactic medium of L ⋆ galaxies through explorations of observed ion tracer gas kinematics and comparisons of observations to different ionization models. For this analysis, we utilize C iv observations from the CIViL ⋆ survey (∼0.14 ≤ z gal ≤ 0.25) and directly compare them to observations of matched lines of sight from the Cosmic Origins Spectrograph-Halos survey. We find that the kinematic parameters for C iv and O vi are likely (>95%) drawn from the same parent distribution, suggesting that these two ions are kinematically coincident and potentially originate under the same physical conditions. We find that the measured C iv /O vi and N v /O vi ratios are inconsistent with single-phase equilibrium models. For 70% of the objects in our sample, regions allowed by the column density ratios in the density-temperature space do not overlap, creating a “zone of avoidance.” We also investigate the origins of C iv , N v , and O vi by exploring a cooling flow model under collisional ionization. We find that both N v and O vi are consistent with the predictions of the model, but the column densities of C iv are ∼2.5 times higher than the predictions. As C iv has a lower ionization energy than N v and O vi , it is possible that C iv has contributions from both the warm/hot and cool photoionized phase.}, archive = {J_ApJ}, author = {Samantha L. Garza and Yakov Faerman and Trystyn A. M. Berg and Jessica K. Werk and Benjamin D. Oppenheimer and Rongmon Bordoloi and Sara Ellison}, doi = {10.3847/1538-4357/ae0304}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {44}, shortjournal = {The Astrophys. J.}, title = {Highly ionized gas in the zone of avoidance: Using the CIViL⋆ survey to pinpoint physical conditions of gaseous halos}, volume = {993}, year = {2025}, }
• (2025). Synthetic ca ii 8542 Å stokes profile associated with chromospheric magnetic reconnection in a simulated active region. ApJ, 993(1), 43. (www)

  @article{ , abstract = {Magnetic reconnection is an important driving mechanism of many chromospheric phenomena, e.g., UV bursts and chromospheric jets. Information about magnetic fields is indispensable for analyzing chromospheric magnetic reconnection, which is mainly encoded in polarization signals. The purpose of this work is to predict possible Stokes features related to chromospheric reconnection events, from realistic two-dimensional magnetohydrodynamic simulation and Stokes profile synthesis. An emerging magnetic flux sheet is imposed at the bottom boundary of a well-relaxed unipolar atmosphere that spans from the upper convection zone to the corona. The reconnection region is heated to ∼7 kK and the outflow velocity reaches up to ∼35 km s −1 . Through Stokes profile synthesis, several Stokes features related to reconnections and plasmoids are reproduced. We found sign reversal features on circular polarization and amplitude reduction features on linear polarization at reconnection sites. Also, we report strong linear and circular polarization signals corresponding to huge (∼300 km) and tiny (∼40 km) plasmoids, respectively. We conclude that both linear and circular polarization signals may reveal the distinctive physical mechanisms in reconnections and enhance our understanding of magnetic reconnection in observations.}, archive = {J_ApJ}, author = {Xinyu Zhou and Takaaki Yokoyama and Haruhisa Iijima and Takuma Matsumoto and Shin Toriumi and Yukio Katsukawa and Masahito Kubo}, doi = {10.3847/1538-4357/ae045e}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {43}, shortjournal = {The Astrophys. J.}, title = {Synthetic ca ii 8542 Å stokes profile associated with chromospheric magnetic reconnection in a simulated active region}, volume = {993}, year = {2025}, }
• (2025). Environment of SDSS quasars at z = 0.4–1.0 explored by subaru HSC. ApJ, 993(1), 42. (www)

  @article{ , abstract = {The relationship between quasars and their galaxy environment is important for understanding the evolution of galaxies and supermassive black holes, but it is not fully understood. We perform a wide and deep exploration of the environment of quasars at 0.4 < z < 1.0 using the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) survey. We investigate the environment of the 1912 spectroscopically selected quasars from the Sloan Digital Sky Survey (SDSS), using photometrically selected galaxies from the HSC-SSP data, over an area of 505 deg 2 . The quasar environment is compared to the environment of matched galaxies with similar stellar mass and redshift. We employ the k -nearest neighbor method to define the local galaxy number density for both the quasars and the matched galaxies at a scale of a few hundred kpc. As a result, we find that the number density of galaxies around SDSS quasars is lower than that of the matched galaxies by ∼11%–20%. We also investigate possible correlations between the local galaxy number densities and the quasar properties such as black hole mass ( M BH ) and Eddington ratio ( R Edd ). We find that the number density is weakly correlated with M BH and only marginally with R Edd . The apparent correlation with M BH is likely driven by their common dependence on redshift rather than a direct physical connection, while the marginal trend with R Edd is statistically insignificant. These results suggest that the quasar activity is not triggered by the high number density of surrounding galaxies at the scale of a few hundred kpc.}, archive = {J_ApJ}, author = {Kohei Shibata and Tohru Nagao and Hisakazu Uchiyama and Mariko Kubo and Yoshiki Toba and Kiyoaki Christopher Omori and Toshihiro Kawaguchi and Yuta Suzuki and Sadman Shariar Ali}, doi = {10.3847/1538-4357/ae0471}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {42}, shortjournal = {The Astrophys. J.}, title = {Environment of SDSS quasars at z = 0.4–1.0 explored by subaru HSC}, volume = {993}, year = {2025}, }
• (2025). Simulations of flare chemistry in brown dwarf companions to active m dwarfs. ApJ, 993(1), 41. (www)

  @article{ , abstract = {Brown dwarfs that are short-period (<10 days) companions to actively flaring M dwarfs may provide a context to directly observe flare-driven photochemistry and structural changes in an extrasolar planet-like atmosphere. To assess the viability of directly observing flare impacts in the atmosphere of a brown dwarf, we perform self-consistent temperature–chemistry modeling of the atmospheric response to individual energetic superflares. We modified the existing open-source VULCAN chemical–kinetics and HELIOS radiative-transfer codes for this purpose. Similar to previous studies of flare impacts on hydrogen-dominated atmospheres, we find flares are capable of orders-of-magnitude changes in the mixing abundances of many chemical species, including important opacity sources like CH 4 and CO 2 . However, due to the fast chemical timescales resulting from high temperatures and densities in brown dwarf atmospheres, these changes last for a short period of time, generally less than a day, and are only plausibly observable via high-resolution emission spectroscopy. We find that the most observable, short-term spectral changes in hot ( T eff ∼ 2000 K), high-gravity ( {\rm{log}}\,g\,\sim 5 ), cloudless brown dwarfs are the photolysis of H 2 O and an enhancement of CO 2 , which can result in part-per-thousands spectral changes in the hours after a flare.}, archive = {J_ApJ}, author = {Aidan Gibbs and Michael P. Fitzgerald}, doi = {10.3847/1538-4357/ae0477}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {41}, shortjournal = {The Astrophys. J.}, title = {Simulations of flare chemistry in brown dwarf companions to active m dwarfs}, volume = {993}, year = {2025}, }
• (2025). Temporal evolution of quasiperiodic oscillations in an accreting black hole swift j1727.8-1613: Coevolution of the Disk–Corona during the state transition. ApJ, 993(1), 40. (www)

  @article{ , abstract = {Low-frequency quasiperiodic oscillations (QPOs) are commonly observed in black hole X-ray binaries, and their frequency has been found to correlate with various spectral properties. In this work, we present a detailed timing analysis of Swift J1727.8-1613, revealing a novel two-branch correlation between the QPO frequency and the observed disk emission, which differs from previous findings of a single correlation. Specifically, at QPO frequencies below 3 Hz, the QPO frequency is negatively correlated with the observed disk emission. This negative relation transitions to a positive one, as the QPO frequency exceeds approximately 3 Hz. The correlation between QPO frequency and Compton flux exhibits an opposite trend, with a positive correlation at lower frequencies and a negative correlation at higher ones. We interpret these behaviors as signatures of an evolving disk–corona geometry, within the framework of a Lense–Thirring precessing hot flow. Additionally, we find that during the flare state, the QPO fractional rms remains nearly constant above 15 keV, but increases with energy below this threshold. The slope of the rms–energy relation increases as the energy spectrum softens.}, archive = {J_ApJ}, author = {Sai-En Xu and Bei You and Yi Long and Han He}, doi = {10.3847/1538-4357/ae058a}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {40}, shortjournal = {The Astrophys. J.}, title = {Temporal evolution of quasiperiodic oscillations in an accreting black hole swift j1727.8-1613: Coevolution of the Disk–Corona during the state transition}, volume = {993}, year = {2025}, }
• (2025). SN 2023ixf in m101: Physical parameters from bolometric light curve modeling. ApJ, 993(1), 39. (www)

  @article{ , abstract = {We present new photometric observations of the core-collapse supernova SN 2023ixf occurred in M101, taken with the RC 80 and BRC80 robotic telescopes in Hungary. The initial nickel mass from the late-phase bolometric light curve extending up to 400 days after explosion, is inferred as M Ni = 0.046 ± 0.007 M ⊙ . The comparison of the bolometric light curve with models from hydrodynamical simulations as well as semi-analytic radiative diffusion codes reveals a relatively low-mass ejecta of M ej ≲ 9 M ⊙ , contrary to SN 2017eaw, another H-rich core-collapse event, which had M ej ≳ 15 M ⊙ .}, archive = {J_ApJ}, author = {József Vinkó and Zsófia Réka Bodola and Ákos Gődény and Szelina Fruzsina Csák and Réka Könyves-Tóth and Andrea P. Nagy and Tamás Szalai and Dominik Bánhidi and Imre Barna Bíró and Attila Bódi and Zsófia Bora and István Csányi and Borbála Cseh and Tibor Hegedüs and Ágoston Horti-Dávid and András Péter Joó and Csilla Kalup and Levente Kriskovics and Erika Mochnács and András Pál and Zsolt Regály and Bálint Seli and Ádám Sódor and Norton Olivér Szabó and Róbert Szakáts and Péter Székely and Vázsony Varga and Krisztián Vida}, doi = {10.3847/1538-4357/ae0614}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {39}, shortjournal = {The Astrophys. J.}, title = {SN 2023ixf in m101: Physical parameters from bolometric light curve modeling}, volume = {993}, year = {2025}, }
• (2025). The hot inner AU of v883 ori. ApJ, 993(1), 38. (www)

  @article{ , abstract = {The V883 Ori system is a rapidly accreting young stellar object that has been used as a laboratory for studying the molecular inventory of young circumstellar disks with high luminosity. We simultaneously fit high-resolution spectroscopy and medium-resolution spectrophotometry of the system to constrain the physical conditions in the inner au. Using our thin viscous accretion disk model, we find \dot{M}=1{0}^{-3.9\pm 0.2}\,{M}_{\odot } yr −1 , R inner = 5.86 ± 1 R ⊙ , i = 38 \mathop{.}\limits^{\unicode{x000b0}} 2 ± 3°, and A V = 20.8 ± 0.7 mag, resulting in an accretion luminosity of 458 L ⊙ and maximum disk temperature of 7045 K. The optical portion of the spectral energy distribution greatly exceeds the flux level expected for a highly extincted accretion disk. We propose that the excess emission arises from a contribution due to scattering of the accretion disk spectrum off nearby envelope material that is viewed along a line of sight with less extinction. Additionally, we use photometric observations spanning 137 years to demonstrate that the source has accreted at least 18 M Jup of disk material to date. Finally, we discuss the importance of considering both the viscous heating from the midplane and the consequent irradiation effects on the outer disk when modeling the temperature structure to reproduce millimeter-wavelength observations.}, archive = {J_ApJ}, author = {Adolfo S. Carvalho and Lynne A. Hillenbrand and Ágnes Kóspál}, doi = {10.3847/1538-4357/ae0646}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {38}, shortjournal = {The Astrophys. J.}, title = {The hot inner AU of v883 ori}, volume = {993}, year = {2025}, }
• (2025). Polarized signatures of variable worlds: Modeling heterogeneous habitable earth- and early mars-like (Exo)planets. ApJ, 993(1), 36. (www)

  @article{ , abstract = {Determining the habitability of terrestrial exoplanets is a complex problem that represents the next major step for the astrophysical community. The majority of current models treat these planets as homogeneous or contain heterogeneity that is constant in time. In reality, habitable exoplanets are expected to contain atmospheric and surface heterogeneities similar to Earth, with diurnal rotation, seasonal changes, and weather patterns resulting in complex, time-dependent signatures. Due to its ability to measure light as a vector, polarimetry provides an important tool that will enhance the characterizations of heterogeneous worlds. Here we model the visible to near-infrared linear spectropolarimetric signatures, as functions of wavelength and planetary phase angle, of various heterogeneous Earth scenarios as well as the first signals of an early wet and potentially habitable Mars. The contributions from the different atmospheric and surface properties result in asymmetric phase curves and variable spectra, with the polarization appearing to be more sensitive than flux to heterogeneities such as patchy clouds and continents moving into and out of view. Our models provide important predictions of expected polarized and unpolarized signatures of heterogeneous exoplanets that will help guide the designs and observing plans of future polarimeters, including those proposed for the upcoming Habitable Worlds Observatory.}, archive = {J_ApJ}, author = {Kenneth E. Goodis Gordon and Theodora Karalidi and Kimberly M. Bott and Connor J. Vancil and Maxwell A. Millar-Blanchaer and Nicholas F. Wogan and Eric T. Wolf}, doi = {10.3847/1538-4357/ae07df}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {36}, shortjournal = {The Astrophys. J.}, title = {Polarized signatures of variable worlds: Modeling heterogeneous habitable earth- and early mars-like (Exo)planets}, volume = {993}, year = {2025}, }
• (2025). Episodic feedback in triple active galactic nucleus candidate SDSS j0849+1114 revealed by extended ionized gas. ApJ, 993(1), 35. (www)

  @article{ , abstract = {Galaxy mergers funnel gas toward the nuclei, igniting starbursts and active galactic nuclei (AGNs). The AGN feedback can reshape the host galaxy and regulate both star formation and supermassive black hole accretion. Using Very Large Telescope/MUSE integral-field spectroscopy, we conduct a spatially resolved study of the triple-AGN candidate SDSS J0849+1114. Extended ionized gas structures (>10 kpc from nucleus A) primarily associated with tidal tails are detected. Meanwhile, two distinct ionized gas outflows are revealed. One extends over >5 kpc around nuclei A with a kinetic power of {\dot{E}}_{{\rm{out}},{\rm{A}}}=3.0\times 1{0}^{42}\,{\rm{erg}}\,{{\rm{s}}}^{-1} , which might be driven by the radio jet. The other outflow extends ∼5.9 kpc around nucleus C, with a kinetic power of {\dot{E}}_{{\rm{out}},{\rm{C}}} = 2.0 × 10 40 erg s −1 . High [O iii ]/H α and [N ii ]/H α ratios in the tidal gas require that nucleus A radiated at a high accretion rate with L A,bol ∼ 0.1–0.5 L Edd,A at least ∼3–×10 4 yr ago, 20–100 times brighter than today. Combined with multiwavelength constraints, we find evidence for episodic AGN feedback that expelled circumnuclear gas and rapidly quenched accretion. This triple AGN candidate demonstrates how AGN feedback can self-regulate black hole growth and impact hosts during mergers.}, archive = {J_ApJ}, author = {Xiaoyu Xu and Meicun Hou and Zhiyuan Li and Sijia Peng and Zhao Su and Zongnan Li and Fuyan Bian and Junfeng Wang}, doi = {10.3847/1538-4357/ae0cb0}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {35}, shortjournal = {The Astrophys. J.}, title = {Episodic feedback in triple active galactic nucleus candidate SDSS j0849+1114 revealed by extended ionized gas}, volume = {993}, year = {2025}, }
• (2025). Hunt for the mHz variability in TESS and XMM-newton observations of nova-like cataclysmic variables. ApJ, 993(1), 34. (www)

  @article{ , abstract = {We analysed the flickering of selected nova-like cataclysmic variables observed by the TESS satellite and XMM-Newton. We searched for break frequencies ( f b ) in the corresponding power density spectra (PDSs), and for any long-term evolution. We find a new optical f b in three nova-like systems, and confirm that the value of this frequency is clustered around 1 mHz. V504 Cen and V751 Cyg show possible X-ray counterparts of f b that had previously only been seen in MV Lyr. This points toward the very central disk for source localization. We investigated a previously proposed correlation between white dwarf mass and f b , but thanks to the new measurements, we do not confirm its existence. V3885 Sgr and V1193 Ori show flaring activity in the long-term light curve during which TESS observations were made. The corresponding PDSs show changes in shape and the disappearance of f b . TT Ari and SGRt 062340.2−265715 exhibit smooth changes in the long-term optical light curve, and the corresponding TESS observations show variable f b during these changes. f b is higher at lower brightness levels, which so far has been observed only in MV Lyr.}, archive = {J_ApJ}, author = {Andrej Dobrotka and Jozef Magdolen and Martin Melicherčík}, doi = {10.3847/1538-4357/ae01a0}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {34}, shortjournal = {The Astrophys. J.}, title = {Hunt for the mHz variability in TESS and XMM-newton observations of nova-like cataclysmic variables}, volume = {993}, year = {2025}, }
• (2025). Classification of radio backgrounds at cosmic dawn and 21 cm signal confirmation using neural networks. ApJ, 993(1), 33. (www)

  @article{ , abstract = {Several ongoing and upcoming radio telescopes aim to detect either the global 21 cm signal or the 21 cm power spectrum. The extragalactic radio background, as detected by ARCADE-2 and LWA-1, suggests a strong radio background from cosmic dawn, which can significantly alter the cosmological 21 cm signal, enhancing both the global signal amplitude and the 21 cm power spectrum. In this paper, we employ an artificial neural network (ANN) to check if there is a radio excess over the cosmic microwave background in mock data, and if present, we classify its type into one of two categories, a background from high-redshift radio galaxies or a uniform exotic background from the early Universe. Based on clean data (without observational noise), the ANN can predict the type of background radiation with 96% accuracy for the power spectrum and 90% for the global signal. Although observational noise reduces the accuracy, the results remain quite useful. We also apply ANNs to map the relation between the 21 cm power spectrum and the global signal. By predicting the global signal using the 21 cm power spectrum, an ANN can estimate the global signal range consistent with an observed power spectrum from SKA-like experiments. Conversely, we show that an ANN can predict the 21 cm power spectrum over a wide range of redshifts and wavenumbers given the global signal over the same redshifts. Such trained networks can potentially serve as valuable tools for cross-confirmation of the 21 cm signal.}, archive = {J_ApJ}, author = {Sudipta Sikder and Anastasia Fialkov and Rennan Barkana}, doi = {10.3847/1538-4357/ae0587}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {33}, shortjournal = {The Astrophys. J.}, title = {Classification of radio backgrounds at cosmic dawn and 21 cm signal confirmation using neural networks}, volume = {993}, year = {2025}, }
• (2025). Star formation rates, metallicities, and stellar masses on kiloparsec scales in TNG50. ApJ, 993(1), 32. (www)

  @article{ , abstract = {Integral field units have extended our knowledge of galactic properties to kiloparsec (or, sometimes, even smaller) patches of galaxies. These scales are where the physics driving galaxy evolution (feedback, chemical enrichment, etc.) take place. Quantifying the spatially resolved properties of galaxies, both observationally and theoretically, is therefore critical to our understanding of galaxy evolution. To this end, we investigate spatially resolved scaling relations within galaxies of M ⋆ > 10 9.0 at z = 0 in IllustrisTNG. We examine both the resolved star formation main sequence (rSFMS) and the resolved mass–metallicity relation (rMZR) using 1 kpc × 1 kpc maps. We find that the rSFMS in IllustrisTNG is well described by a power law but is significantly shallower than the observed rSFMS. However, the disagreement between the rSFMS of IllustrisTNG and observations is likely driven by an overestimation of AGN feedback in IllustrisTNG for the higher-mass hosts. Conversely, the rMZR for IllustrisTNG has very good agreement with observations. Furthermore, we argue that the rSFMS is an indirect result of the Schmidt–Kennicutt law and local gas relation, which are both independent of host galaxy properties. Finally, we expand upon a localized leaky-box model to study the evolution of idealized spaxels and find that it provides a good description of these resolved relations. The degree of agreement, however, between idealized spaxels and simulated spaxels depends on the “net” outflow rate for the spaxel, and the IllustrisTNG scaling relations indicate a preference for a low net outflow rate.}, archive = {J_ApJ}, author = {Jia Qi and Alex M. Garcia and Davis Robinson and Paul Torrey and Jorge Moreno and Kara N. Green and Aaron S. Evans and Z. S. Hemler and Lars Hernquist and Sara L. Ellison}, doi = {10.3847/1538-4357/ae0622}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {32}, shortjournal = {The Astrophys. J.}, title = {Star formation rates, metallicities, and stellar masses on kiloparsec scales in TNG50}, volume = {993}, year = {2025}, }
• (2025). Determining the 3D dynamics of solar flare magnetic reconnection. ApJ, 993(1), 31. (www)

  @article{ , abstract = {Solar flares are major space weather events that result from the explosive conversion of stored magnetic energy into bulk motion, plasma heating, and particle acceleration. While the standard flare model has proven highly successful in explaining key morphological features of flare observations, many aspects of the energy release are not yet understood. In particular, the turbulent three-dimensional structure of the flare current sheet is thought to play an important role in fast reconnection, particle acceleration, and bursty dynamics. Although direct diagnosis of the magnetic field dynamics in the corona remains highly challenging, rich information may be gleaned from flare ribbons, which represent the chromospheric imprints of reconnection in the corona. Intriguingly, recent solar imaging observations have revealed a diversity of fine structure in flare ribbons that hints at corresponding complexity in the reconnection region. We present high-resolution three-dimensional magnetohydrodynamics simulations of an eruptive flare and describe our efforts to interpret fine-scale ribbon features in terms of the current sheet dynamics. In our model, the current sheet is characterized by many coherent magnetic structures known as plasmoids. We derive a model analog for ribbons by generating a time series of field-line length maps ( L -maps) and identifying abrupt shortenings as flare reconnection events. We thereby demonstrate that plasmoids imprint transient “spirals” along the analog of the ribbon front, with a morphology consistent with observed fine structure. We discuss the implications of these results for interpreting SolO, Interface Region Imaging Spectrograph, and Daniel K. Inouye Solar Telescope observations of explosive flare energy release.}, archive = {J_ApJ}, author = {Joel T. Dahlin and Spiro K. Antiochos and Peter F. Wyper and Jiong Qiu and C. Richard DeVore}, doi = {10.3847/1538-4357/ae03c5}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {31}, shortjournal = {The Astrophys. J.}, title = {Determining the 3D dynamics of solar flare magnetic reconnection}, volume = {993}, year = {2025}, }
• (2025). Feature intensity mapping: Polycyclic aromatic hydrocarbon emission from all galaxies across cosmic time. ApJ, 993(1), 30. (www)

  @article{ , abstract = {Line intensity mapping (LIM) is an emerging technique for probing the aggregate emission of a spectral line from all sources, without requiring individual detections. Through the wavelength–redshift relation, one can map the line-of-sight evolution of the line emission that traces the underlying large-scale structure in a spectral-imaging survey. In this work, we present a new technique—feature intensity mapping—as an extension of the LIM formalism to map broad spectral features in 3D, rather than the narrow emission lines typically targeted by LIM. By accounting for the convolution of spectral features with the instrument’s spectral response across redshift, our technique enables simultaneous constraints on the redshift-dependent emission from multiple features. This approach enables 3D intensity mapping with some of the brightest features in the infrared spectra of galaxies: the polycyclic aromatic hydrocarbon (PAH) emission bands. We forecast the detectability of PAH signals using feature intensity mapping with the ongoing SPHEREx mission in the near-infrared and the proposed PRIMA mission in the far-infrared. We find that a signal-to-noise ratio of ≳10 per redshift bin of widths Δ z = 0.1 and 0.5 can be achieved at z < 0.5 and 1 < z < 5 with SPHEREx and PRIMA, respectively, for multiple PAH features, suggesting a promising prospect for mapping the aggregate PAH emission at cosmological distances with upcoming data sets.}, archive = {J_ApJ}, author = {Yun-Ting Cheng and Brandon S. Hensley and Thomas S.-Y. Lai}, doi = {10.3847/1538-4357/ae044e}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {30}, shortjournal = {The Astrophys. J.}, title = {Feature intensity mapping: Polycyclic aromatic hydrocarbon emission from all galaxies across cosmic time}, volume = {993}, year = {2025}, }
• (2025). OTI on FIRE: Testing the efficacy of orbital torus imaging to recover the galactic potential. ApJ, 993(1), 29. (www)

  @article{ , abstract = {Orbital Torus Imaging (OTI) is a dynamical inference method for determining the Milky Way’s gravitational potential using stellar survey data. OTI uses gradients in stellar astrophysical quantities, such as element abundances, as functions of dynamical quantities, like orbital actions or energy, to estimate the Galactic mass distribution, assuming axisymmetry and a steady state of the system. While preliminary applications of OTI have shown promising outcomes, its sensitivity to disequilibrium effects is unknown. Here, we apply OTI to a benchmark Feedback in Realistic Environments (FIRE-2) cosmological hydrodynamic simulation, m12i, which enables a comparative analysis between known FIRE-2 vertical acceleration profiles and total surface mass densities to the analogous OTI-inferred results. We quantify OTI’s accuracy within 16 solar-analog volumes embedded in the simulated galactic disk. Despite a dynamically evolving system, we find that OTI recovers the known vertical acceleration profiles within 3 σ /1 σ errors for 94%/75% of the volumes considered. We discuss the method’s sensitivity to the local, instantaneous structure of the disk, reporting a loss in accuracy for volumes that have large (>1.5 kpc) scale heights and low total density at z = 1.1 kpc. We present realistic OTI error bars from both Markov Chain Monte Carlo sampling and bootstrapping the FIRE-2 simulated data, which provides a touchstone for interpreting results obtained from current and forthcoming surveys such as SDSS-V, Gaia, WEAVE, and 4MOST.}, archive = {J_ApJ}, author = {Micah Oeur and Sarah R. Loebman and Adrian M. Price-Whelan and Arpit Arora and Lina Necib and Danny Horta}, doi = {10.3847/1538-4357/ae0584}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {29}, shortjournal = {The Astrophys. J.}, title = {OTI on FIRE: Testing the efficacy of orbital torus imaging to recover the galactic potential}, volume = {993}, year = {2025}, }
• (2025). SN 2019hnl: A type IIP supernova with a partially stripped, low-mass progenitor. ApJ, 993(1), 28. (www)

  @article{ , abstract = {We present optical photometry and spectroscopy of SN 2019hnl. Discovered within ∼26 hr of explosion by the ATLAS survey, SN 2019hnl is a typical Type IIP supernova (SN) with a peak absolute V -band magnitude of −16.7 ± 0.1 mag, a plateau length of ∼107 days, and an early decline rate of 0.0086 ± 0.0006 mag (50 days) −1 . We use nebular spectroscopy and hydrodynamic modeling with the snec , mesa , and stella codes to infer that the progenitor of SN 2019hnl was an M ZAMS ∼ 11 M ⊙ red supergiant, which produced 0.047 ± 0.007 M ⊙ of 56 Ni in the explosion. As a part of our hydrodynamic modeling, we reduced hydrogen envelope mass by scaling the mass loss within the “Dutch” wind scheme to fit our light curve, showing that the progenitor of a relatively typical Type IIP SN may experience partial stripping during their evolution and establish massive (∼0.2 M ⊙ ) circumstellar material environments prior to core collapse.}, archive = {J_ApJ}, author = {Aidan Martas and Stefano Valenti and Aravind P. Ravi and Yize Dong and K. Azalee Bostroem and Jeniveve Pearson and Manisha Shrestha and Jennifer E. Andrews and David J. Sand and Griffin Hosseinzadeh and Michael Lundquist and Emily Hoang and Darshana Mehta and Nicolás Meza Retamal and Saurabh W. Jha and Daryl Janzen and D. Andrew Howell and Curtis McCully and Daichi Hiramatsu and Craig Pellegrino}, doi = {10.3847/1538-4357/ae0617}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {28}, shortjournal = {The Astrophys. J.}, title = {SN 2019hnl: A type IIP supernova with a partially stripped, low-mass progenitor}, volume = {993}, year = {2025}, }
• (2025). Simulation of solar surface flux transport constrained by magnetic power spectra. i. flux transport parameter. ApJ, 993(1), 27. (www)

  @article{ , abstract = {The multiscale structure of the solar surface magnetic field is essential for understanding both the Sun’s internal dynamo processes and its external magnetic activity. The surface flux transport (SFT) model has been successful in describing the large-scale evolution of the surface field, but its ability to capture observed multiscale features, quantified by magnetic power spectra, remains uncertain. Here, we evaluate the SFT model by comparing observed and simulated power spectra across a broad range of spatial scales and by analyzing the effects of key transport parameters. We find that the simulations reproduce the observed spectra well at spherical harmonic degrees l ≲ 60, but diverge progressively at smaller spatial scales, l ≳ 60. This divergence likely arises from the diffusion approximation used to model the random walk of supergranulation. Power at 20 ≲ l ≲ 60 is primarily determined by the magnetic flux sources, while at l ≲ 20 the spectra are more sensitive to transport parameters. The meridional flow profile, including its equatorial gradient, peak latitude, and polar distribution, along with turbulent diffusivity, has distinct impacts on the low-degree modes ( l ≤ 5). In particular, a comparison of the l = 3 and l = 5 multipoles strengths suggests that the poleward flow above ∼±60° latitudes is very weak. This study presents the first quantitative validation of SFT models using magnetic power spectra and provides a new constraint on surface flux transport physics.}, archive = {J_ApJ}, author = {Yukun Luo and Jie Jiang and Ruihui Wang}, doi = {10.3847/1538-4357/ae0618}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {27}, shortjournal = {The Astrophys. J.}, title = {Simulation of solar surface flux transport constrained by magnetic power spectra. i. flux transport parameter}, volume = {993}, year = {2025}, }
• (2025). Supra-arcade downflows in an extensive fan associated with a giant quiescent solar filament eruption. ApJ, 993(1), 26. (www)

  @article{ , abstract = {We investigate the aftermath of a giant quiescent solar filament eruption on 2023 December 24. One feature of the eruption is an extensive fan above the filament channel that is about 3 times as wide as similar structures that appear above active regions (ARs) during solar flares. The fan contains numerous supra-arcade downflows (SADs), and we investigate the largest SADs with continuous Hinode X-ray Telescope observations. The measured maximum width of the SADs in this event is at least 3 times the maximum width of SADs observed in AR flares, whereas the velocities of the largest SADs are similar to the typical values of AR SADs. The kinetic characteristics of the largest SADs observed in this event align with previous model predictions, where SADs originate from the nonlinear development of Rayleigh–Taylor-type instabilities. In this scenario, the larger system size allows the existence of larger-scale instabilities, while the development of the velocities of these instabilities is expected to be independent of the system size. Compared to AR flares, the temperature and emission measure in this event are lower, and there is less overall radiation, resulting in no evident Geostationary Operational Environmental Satellite signature. Similar to those in AR flares, SADs show lower temperatures compared to the surrounding fan plasma. Our observations show that SADs are present in a wide variety of eruptions. The reconnection mechanisms present in quiescent filament eruptions are similar to those driving more compact eruptions originating from ARs.}, archive = {J_ApJ}, author = {Xiaoyan Xie and Katharine K. Reeves and Chengcai Shen and Nishu Karna and Yan Xu and Christopher S. Moore and Crisel Suarez and Ritesh Patel and Daniel B. Seaton}, doi = {10.3847/1538-4357/ae0715}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {26}, shortjournal = {The Astrophys. J.}, title = {Supra-arcade downflows in an extensive fan associated with a giant quiescent solar filament eruption}, volume = {993}, year = {2025}, }
• (2025). Forming the noncarbonaceous chondrite parent bodies in the presence of the jupiter barrier. ApJ, 993(1), 25. (www)

  @article{ , abstract = {Meteorites can be divided into two groups—noncarbonaceous chondrite like (NC) and carbonaceous chondrite like (CC)—with distinct stable-isotope compositions. Parent bodies of NC and CC meteorites have overlapping formation ages. This suggests they formed in different regions of the solar nebula, separated by a dynamical barrier that prevented small solids (pebbles) from mixing. NC chondrites would have formed 1–2 Myr after the barrier appeared. Pebbles in the NC region moved inwards due to radial drift and the inward flow of gas. Outward turbulent diffusion partly offset inward advection, but pebble lifetimes were finite. Survival of enough pebbles to form the NC chondrites requires that the gas flow was mainly confined to the surface layers of the solar nebula, and that pebbles remained near the midplane. This sets an upper limit on the strength of turbulence. If pebble size was set by mutual collision speeds, then turbulence strength has a lower limit as well, set by the maximum acceptable drift rate. For a barrier at 5 au from the Sun, the turbulence parameter α should lie between 2 × 10 −5 and 10 −3 . The maximum collision speed {v}_{{\rm{\max }}} should not exceed 0.8 m s −1 . If the pebble radius remained fixed, it should not exceed 2 mm, which is a few times larger than the mass peak seen in NC chondrules.}, archive = {J_ApJ}, author = {John Chambers}, doi = {10.3847/1538-4357/ae0ad2}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {25}, shortjournal = {The Astrophys. J.}, title = {Forming the noncarbonaceous chondrite parent bodies in the presence of the jupiter barrier}, volume = {993}, year = {2025}, }
• (2025). Unveil a peculiar light-curve pattern of magnetar burst with GECAM observations of SGR j1935+2154. ApJ, 993(1), 24. (www)

  @article{ , abstract = {A magnetar X-ray burst (MXB) is usually composed of a single pulse or multiple pulses with rapid rise and brief duration mostly observed in the hard X-ray (soft gamma-ray) band. Previous work studied the temporal behavior of some magnetar bursts and employed the fast rise exponential decay (FRED) model to fit pulses of MXB. However, whether there is another kind of pulse shape has not been explored. In this study, we systematically examined the light curve of MXBs from SGR J1935+2154 detected by the Gravitational Wave High-energy Electromagnetic Counterpart All-sky Monitor between 2021 and 2022. We find that there are different light-curve morphologies. Especially, we discover a peculiar and new pattern, exponential rise and cutoff decay (ERCOD), which is significantly different from FRED and could be well described by a mathematical function we proposed. We find that MXBs with ERCOD shape are generally longer in duration, brighter in the peak flux, and harder in spectrum than those with FRED. We note that the ERCOD shape is not unique to SGR J1935+2154 but also present in other magnetars. This new light-curve pattern may imply a special burst and radiation mechanism of magnetar.}, archive = {J_ApJ}, author = {Yue Wang and Chen-Wei Wang and Shao-Lin Xiong and Shuo Xiao and Yan-Qiu Zhang and Sheng-Lun Xie and Lin Lin and Yuan-Pei Yang and Hao-Xuan Guo and Ce Cai and Yue Huang and Cheng-Kui Li and Bing Li and Xiao-Bo Li and Jia-Cong Liu and Xiang Ma and Li-Ming Song and Wen-Jun Tan and Ping Wang and Wang-Chen Xue and Shu-Xu Yi and Yun-Wei Yu and Zheng-Hang Yu and Jin-Peng Zhang and Peng Zhang and Shuang-Nan Zhang and Wen-Long Zhang and Zhen Zhang and Xiao-Yun Zhao and Chao Zheng and Shi-Jie Zheng}, doi = {10.3847/1538-4357/ae0cbe}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {24}, shortjournal = {The Astrophys. J.}, title = {Unveil a peculiar light-curve pattern of magnetar burst with GECAM observations of SGR j1935+2154}, volume = {993}, year = {2025}, }
• (2025). The first search for optical transient as a counterpart of a month-timescale IceCube neutrino multiplet event. ApJ, 993(1), 23. (www)

  @article{ , abstract = {Optical transients with timescales of months, such as supernovae (SNe) and tidal disruption events (TDEs), are candidates for high-energy neutrino sources. Multiple neutrino detections from the same direction within a month timescale provide a unique opportunity to identify such optical counterparts in the nearby Universe. In this work, we conduct an archival search for the optical counterpart of an IceCube triplet event using the data of Zwicky Transient Facility. We develop a dedicated alert filtering system and validate the performance by following a blind analysis method. Applying this filtering system to the data after the detections of the IceCube triplet event, we find no transient candidates within the localization area. Assuming that the IceCube triplet event originates from an astrophysical source, we constrain parameters of the optical transient, a peak luminosity, and a decay timescale, using a simple signal model that is motivated by TDEs and superluminous SNe (SLSNe). For the case with no time lag between neutrino detections and optical peak, almost the entire parameter space of the known TDEs and SLSNe would be constrained. To give constraints on transients with a rapidly evolving light curve, quick follow-up observations for future neutrino multiplet events are crucial.}, archive = {J_ApJ}, author = {Seiji Toshikage and Shigeo S. Kimura and Nobuhiro Shimizu and Masaomi Tanaka and Shigeru Yoshida and Wataru B. Iwakiri and Tomoki Morokuma}, doi = {10.3847/1538-4357/adfedf}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {23}, shortjournal = {The Astrophys. J.}, title = {The first search for optical transient as a counterpart of a month-timescale IceCube neutrino multiplet event}, volume = {993}, year = {2025}, }
• (2025). Magnetorotational instability in a solar near-surface mean-field dynamo. ApJ, 993(1), 22. (www)

  @article{ , abstract = {We address the question whether the magnetorotational instability (MRI) can operate in the near-surface shear layer (NSSL) of the Sun and how it affects the interaction with the dynamo process. Using hydromagnetic mean-field simulations of α Ω-type dynamos in rotating shearing-periodic boxes, we show that for negative shear the MRI can operate above a certain critical shear parameter. This parameter scales inversely with the equipartition magnetic field strength above which α quenching set in. Like the usual Ω effect, the MRI produces toroidal magnetic field when the field is sufficiently strong. The work done by the Lorentz force is positive, so the magnetic field drives kinetic energy and not the other way around, as in a turbulent dynamo. This results in strong kinetic energy production and dissipation, which occurs at the expense of the magnetic energy. In view of the application to the solar NSSL, we conclude that the turbulent magnetic diffusivity may be too large for the MRI to be excited and that therefore only the standard Ω effect is expected to operate.}, archive = {J_ApJ}, author = {Axel Brandenburg and Gustav Larsson and Fabio Del Sordo and Petri J. Käpylä}, doi = {10.3847/1538-4357/ae03c4}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {22}, shortjournal = {The Astrophys. J.}, title = {Magnetorotational instability in a solar near-surface mean-field dynamo}, volume = {993}, year = {2025}, }
• (2025). Interactions between solar filaments and coronal loops in active region 13229. ApJ, 993(1), 21. (www)

  @article{ , abstract = {We present a multiwavelength observational investigation of filaments and coronal loop interactions in active region NOAA 13229 during 2023 February 21–23. Our findings demonstrate that a series of interactions between filaments (F1 and F2), coronal loops, and the loop–filament system, mediated by reconnection with overlying hot coronal loops, led to the formation of a longer inverse S-shaped filament. Key mechanisms, including flux convergence, cancellation, and submergence along the polarity inversion line, drive these interactions. Photospheric horizontal plasma flows and the transverse component of the Lorentz force may facilitate footpoint convergence, enabling magnetic reconnection and structural reorganization. The nonlinear force-free field extrapolations indicate that magnetic reconnections likely occur at the interface of loop–loop or filament–loop that drive the formation of large-scale filament systems.}, archive = {J_ApJ}, author = {Shahid Idrees and Li Feng and Suo Liu and Yijun Hou and Yongliang Song and Yongyuan Xiang and Jie Chen and Yuanyong Deng and Jiangtao Su}, doi = {10.3847/1538-4357/ae0474}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {21}, shortjournal = {The Astrophys. J.}, title = {Interactions between solar filaments and coronal loops in active region 13229}, volume = {993}, year = {2025}, }
• (2025). A statistical study of the gamma-ray burst and supernova association. ApJ, 993(1), 20. (www)

  @article{ , abstract = {The association between long gamma-ray bursts (LGRBs) and core-collapse supernovae (SNe) has been well established since the discovery of SN 1998bw, which was linked to the low-luminosity LGRB 980425. However, long-term monitoring of several well-localized, low-redshift LGRBs has yielded compelling evidence for the absence of accompanying SNe. Notably, two long bursts, GRB 211211A and GRB 230307A, show signatures consistent with kilonova emission from compact binary mergers, indicating that at least some long events may originate from progenitors other than core-collapse SNe. In this study, we conduct a comparative analysis of two samples of LGRBs, i.e., LGRBs with and without SN associations, to investigate the differences that may reveal intrinsic distinctions in their progenitors. A detailed examination of their prompt emission properties, host galaxy environments, and event rates is performed. While the two samples exhibit considerable overlap in most observed properties, a significant discrepancy in their event rate is revealed. LGRBs without SN association have an event rate that aligns well with the star formation rate, whereas that of SN-associated LGRBs differs significantly. It indicates that LGRBs without an SN association may constitute a distinct subclass with intrinsically different progenitors.}, archive = {J_ApJ}, author = {Xiao-Fei Dong and Yong-Feng Huang and Zhi-Bin Zhang and Jin-Jun Geng and Chen Deng and Ze-Cheng Zou and Chen-Ran Hu and Orkash Amat}, doi = {10.3847/1538-4357/ae04e7}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {20}, shortjournal = {The Astrophys. J.}, title = {A statistical study of the gamma-ray burst and supernova association}, volume = {993}, year = {2025}, }
• (2025). Electrons in the collisionally young solar wind: Parker solar probe observations. ApJ, 993(1), 19. (www)

  @article{ , abstract = {We report new observations by the Parker Solar Probe of unique electron velocity distribution functions (VDFs) in low-density solar wind streams at heliocentric distances of ∼10–20 R ⊙ . These VDFs have a significant core anisotropy and lack a clear energy spectral break point between the thermal core and suprathermal strahl populations, with a parallel cut through the anti-sunward distribution closely following a single-temperature Maxwellian function over up to ∼6 decades in distribution function. These characteristics correlate strongly with low collisional age parameters and high Knudsen numbers, and also to some degree with higher local and asymptotic bulk solar wind flow speeds and lower strahl temperatures. The observed VDFs may represent a unique characteristic of low-density solar wind streams, or alternatively they could represent a common occurrence in any sufficiently collisionally young stream. In either case, these observations have implications both for the detailed evolution of the electron VDF and the large-scale structure and acceleration of the solar wind.}, archive = {J_ApJ}, author = {J. S. Halekas and P. Whittlesey and D. E. Larson and M. L. Stevens and R. Livi and S. D. Bale}, doi = {10.3847/1538-4357/ae0611}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {19}, shortjournal = {The Astrophys. J.}, title = {Electrons in the collisionally young solar wind: Parker solar probe observations}, volume = {993}, year = {2025}, }
• (2025). A theoretical study of carbon nanotube formation: Carriers of the diffuse interstellar bands?. ApJ, 993(1), 18. (www)

  @article{ , abstract = {Density functional theory (DFT) calculations have been conducted to probe the formation of carbon nanotubes (CNTs) from graphitic sheets in the presence of a simulated circumstellar shock wave. The sheets serve as a model for graphite layers formed on surfaces of SiC grains, as produced in experiments. The computations show that when the top graphite layer is displaced toward a lower layer under the mechanical stress of a shock, the sheets bond and curl into a CNT. The bonding between sheets always occurs along the zigzag edges, exclusively producing the “armchair” CNT or ( n , m ) conformer, where n = m , as opposed to the “zigzag” or “chiral” forms ( n ≠ m ). Multilayered graphite sheets showed the same behavior when the top sheet was mechanically perturbed, also leading to formation of energy-minimum armchair CNT structures. The optical-transition energies from the ground to first excited state for a series of armchair CNTs, E 11 , were calculated. Within uncertainties associated with DFT calculations, the wavelengths of the E 11 transitions of the (5, 5), (8, 8), (9, 9), (10, 10), and (12, 12) CNTs match the pattern of five of the six strongest diffuse interstellar bands (DIBs), including those at 4430, 5780, and 6284 Å. These DIBs are also found in the planetary nebulae Tc-1 and M1-20, where C 60 and C 70 have been identified. These data further support the hypothesis that CNTs, as well as fullerenes, are formed in shocked circumstellar gas from the destruction of SiC grains and are transported into the diffuse interstellar medium.}, archive = {J_ApJ}, author = {A. Thakur and P. J. Lohr and J. J. Bernal and A. Asaduzzaman and K. Muralidharan and T. J. Zega and L. M. Ziurys}, doi = {10.3847/1538-4357/ae06a3}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {18}, shortjournal = {The Astrophys. J.}, title = {A theoretical study of carbon nanotube formation: Carriers of the diffuse interstellar bands?}, volume = {993}, year = {2025}, }
• (2025). The effects of linear matter power spectrum enhancement on dark matter substructure. ApJ, 993(1), 17. (www)

  @article{ , abstract = {We present cosmological dark matter (DM)–only zoom-in simulations of a Milky Way analog originating from enhanced linear matter power spectra P ( k ) relative to the standard cold, collisionless DM (CDM) cosmology. We consider a Gaussian power excess in P ( k ) followed by a cutoff in select cases; this behavior could arise from early-Universe physics that alters the primordial matter power spectrum or DM physics in the radiation-dominated epoch. We find that enhanced initial conditions (ICs) lead to qualitative differences in substructure relative to CDM. In particular, the subhalo mass function (SHMF) resulting from ICs with both an enhancement and a cutoff is amplified at high masses and suppressed at low masses, indicating that DM substructure is sensitive to features in P ( k ). Critically, the amplitude and shape of the SHMF enhancement depend on the wavenumber of the P ( k ) excess and the presence or absence of a cutoff on smaller scales. These alterations to the SHMF are mainly imprinted at infall rather than during tidal evolution. Additionally, subhalos are found systematically closer to the host center, and their concentrations are increased in scenarios with P ( k ) enhancement. Our work thus reveals effects that must be captured to enable P ( k ) reconstruction using DM substructure.}, archive = {J_ApJ}, author = {Ethan O. Nadler and Vera Gluscevic and Andrew Benson}, doi = {10.3847/1538-4357/ae073b}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {17}, shortjournal = {The Astrophys. J.}, title = {The effects of linear matter power spectrum enhancement on dark matter substructure}, volume = {993}, year = {2025}, }
• (2025). Asymptotic giant branch mass-loss rates and metal yields from scaled mixing-length and mass-loss parameters. ApJ, 993(1), 16. (www)

  @article{ , abstract = {Stars on the asymptotic giant branch (AGB) enrich the interstellar medium with carbon, nitrogen, and dust, which in turn boost cooling and promote future generations of planet and star formation. They are poorly constrained observationally because they remain in this phase briefly and modeling them is also challenging due to complex convective mixing and nucleosynthesis. By incorporating updated opacity tables and instability management techniques into MESA, we compute a new grid of AGB models that densely samples a wide range of initial masses (0.8 ≤ M/M ⊙ ≤ 7) and metal mass fractions (0.0001 ≤ Z ≤ 0.03), and generate updated AGB mass-loss rates and metal yields up to 28 Si for evolution models and cosmological simulations. We develop scaling formulas for varying the convective mixing-length and Blöcker mass-loss parameters, enabling calibration against recent carbon star luminosity observations and hydrodynamic simulation results. Our results are consistent with white dwarf initial–final mass observations, typical AGB mass-loss rates of ∼10 −7 –10 −5 M ⊙ yr −1 , and average luminosities of carbon stars in AGB populations of ∼8200 L ⊙ . We compare yields to previous models, finding similar C, N, O, F, and Ne but significantly enhanced Mg. The surface C/O ratios match other models at high metallicity but tend to be higher at Z ≤ 0.005. Predicted surface metallicities match previous simulation assumptions, but significantly higher AGB outflow rates suggest large systematic uncertainties in the theoretically expected cosmological carbon yield.}, archive = {J_ApJ}, author = {Ezra Huscher and Kristian Finlator and Jason Jackiewicz}, doi = {10.3847/1538-4357/ae0199}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {16}, shortjournal = {The Astrophys. J.}, title = {Asymptotic giant branch mass-loss rates and metal yields from scaled mixing-length and mass-loss parameters}, volume = {993}, year = {2025}, }
• (2025). Detecting electromagnetic counterparts to LIGO/Virgo/KAGRA gravitational-wave events with DECam: Neutron star mergers. ApJ, 993(1), 15. (www)

  @article{ , abstract = {With GW170817 being the only multimessenger gravitational-wave (GW) event with an associated kilonova detected so far, there exists a pressing need for realistic estimation of the GW localization uncertainties and rates, as well as optimization of available telescope time to enable the detection of new kilonovae. We simulate GW events assuming a data-driven distribution of binary parameters for the LIGO/Virgo/KAGRA fourth and fifth observing runs (O4 and O5). We map the binary neutron star (BNS) and neutron star–black hole (NSBH) properties to the kilonova optical light curves. We use the simulated population of kilonovae to generate follow-up observing plans, with the primary goal of optimizing detection with the Gravitational Wave Multi-Messenger Astronomy DECam Survey. We explore the dependence of kilonova detectability on the mass, distance, inclination, and spin of the binaries. Assuming that no BNS was detected during O4 until the end of 2024, we present updated GW BNS (NSBH) merger detection rates. We expect to detect BNS (NSBH) kilonovae with DECam at a per-year rate of 0–2.0 (0) in O4 and 2.0–19 (0–1.0) in O5. We expect the majority of BNS detections and also those accompanied by a detectable kilonova to produce a hypermassive NS remnant, with a significant fraction of the remaining BNSs promptly collapsing to a BH. We release GW simulations and depths required to detect kilonovae based on our predictions to support the astronomical community in their multimessenger follow-up campaigns and analyses.}, archive = {J_ApJ}, author = {K. Kunnumkai and A. Palmese and A. M. Farah and M. Bulla and T. Dietrich and P. T. H. Pang and S. Anand and I. Andreoni and T. Cabrera and B. O’Connor}, doi = {10.3847/1538-4357/ae0336}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {15}, shortjournal = {The Astrophys. J.}, title = {Detecting electromagnetic counterparts to LIGO/Virgo/KAGRA gravitational-wave events with DECam: Neutron star mergers}, volume = {993}, year = {2025}, }
• (2025). Late-time evolution of magnetized disks in tidal disruption events. ApJ, 993(1), 14. (www)

  @article{ , abstract = {In classic time-dependent 1D accretion-disk models, the inner radiation-pressure-dominated regime is viscously unstable. However, late-time observations of accretion disks formed in tidal disruption events (TDEs) do not exhibit evidence of such instabilities. The common theoretical response is to modify the viscosity parameterization, but the typically used viscosity parameterizations are generally ad hoc. In this study, we take a different approach and investigate a time-dependent 1D α -disk model, in which the pressure is dominated by magnetic fields rather than photons. We compare the time evolution of thermally stable, strongly magnetized TDE disks to the simpler linear viscosity model. We find that the light curves of magnetized disks evolve as L UV ∝ t −5/6 for decades to centuries and that this same evolution can be reproduced by the linear viscosity model for specific parameter choices. Additionally, we show that TDEs remain ultraviolet-bright for many years, suggesting we could possibly find fossil TDEs decades after their bursts. We estimate that ULTRASAT could detect hundreds of such events, providing an opportunity to study late-stage TDE physics and supermassive black hole properties. Finally, we explore the connection between TDE disks and quasiperiodic eruptions (QPEs) suggested by recent observations. One theoretical explanation involves TDE disks expanding to interact with extreme-mass-ratio inspirals (EMRIs), which produce X-ray flares as the EMRI passes through the disk. Our estimates indicate that magnetized TDE disks should exhibit QPEs earlier than those observed in AT2019qiz, suggesting that the QPEs may have begun before their first detection.}, archive = {J_ApJ}, author = {Yael Alush and Nicholas C. Stone}, doi = {10.3847/1538-4357/adf217}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {14}, shortjournal = {The Astrophys. J.}, title = {Late-time evolution of magnetized disks in tidal disruption events}, volume = {993}, year = {2025}, }
• (2025). FEAST: JWST uncovers the emerging timescales of young star clusters in m83. ApJ, 993(1), 13. (www)

  @article{ , abstract = {We present JWST NIRCam observations of the emerging young star clusters (eYSCs) detected in the nearby spiral galaxy M83. The NIRcam mosaic encompasses the nuclear starburst, the bar, and the inner spiral arms. The eYSCs, detected in Pa α and Br α maps, have been largely missed in previous optical campaigns of young star clusters (YSCs). We distinguish between eYSCI, if they also have compact 3.3 μ m polycyclic aromatic hydrocarbon (PAH) emission associated with them, and eYSCII, if they only appear as compact Pa α emitters. We find that the variations in the 3.3 μ m PAH feature are consistent with an evolutionary sequence where eYSCI evolve into eYSCII and then optical YSCs. This sequence is clear in the F300M​​​​​​−F335M (tracing the excess in the 3.3 μ m PAH feature) and the F115W−F187N (tracing the excess in Pa α ) colors, which become increasingly bluer as clusters emerge. The central starburst stands out as the region where the most massive eYSCs are currently forming in the galaxy. We estimate that only about 20% of eYSCs will remain detectable as compact YSCs. Combining eYSCs and YSCs (≤10 Myr), we recover an average clearing timescale of 6 Myr in which clusters transition from embedded to fully exposed. We see evidence of shorter emergence timescales (∼5 Myr) for more massive (>5 × 10 3 M ⊙ ) clusters, while star clusters of ∼10 3 M ⊙ about 7 Myr. We estimate that eYSCs remain associated with the 3.3 μ m PAH emission for 3–4 Myr. Larger samples of eYSC and YSC populations will provide stronger statistics to further test environmental and cluster mass dependencies on the emergence timescale.}, archive = {J_ApJ}, author = {Alice Knutas and Angela Adamo and Alex Pedrini and Sean T. Linden and Varun Bajaj and Jenna E. Ryon and Benjamin Gregg and Ahmad A. Ali and Eric P. Andersson and Arjan Bik and Giacomo Bortolini and Anne S. M. Buckner and Daniela Calzetti and Ana Duarte-Cabral and Bruce G. Elmegreen and Helena Faustino Vieira and John S. Gallagher and Kathryn Grasha and Kelsey Johnson and Thomas S.-Y. Lai and Drew Lapeer and Matteo Messa and Göran Östlin and Elena Sabbi and Linda J. Smith and Monica Tosi}, doi = {10.3847/1538-4357/ae018c}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {13}, shortjournal = {The Astrophys. J.}, title = {FEAST: JWST uncovers the emerging timescales of young star clusters in m83}, volume = {993}, year = {2025}, }
• (2025). Bridging unstratified and stratified simulations of the streaming instability for τs = 0.1 grains. ApJ, 993(1), 12. (www)

  @article{ , abstract = {The streaming instability (SI), driven by aerodynamic coupling between solids and gas under a global radial pressure gradient, concentrates solids and facilitates planetesimal formation. Unstratified simulations are commonly used to study the SI, based on the assumption that they approximate conditions near the disk midplane. However, it remains unclear how accurately these unstratified simulations capture the midplane dust–gas dynamics in stratified disks. To address this, we examine the saturated state of the SI in stratified simulations and compare the dust–gas dynamics to those in unstratified simulations across various radial pressure gradients. To this end, we consider a dimensionless dust stopping time ( τ s ) of 0.1 and perform 2D axisymmetric, stratified simulations. We find that the formation of dust filaments during dust settling exhibits morphological similarities to those in unstratified simulations. Vertical gravity acts to redistribute momentum vertically in response to momentum flux, resulting in midplane velocities in the center-of-mass frame that are consistent with those from unstratified models at any given pressure gradient. Furthermore, the velocity dispersions and density distributions of the gas and dust near the midplane of our stratified simulations closely match those in unstratified simulations. While further exploration across the parameter space is needed, our results suggest that, for τ s = 0.1, unstratified simulations represent well the midplane dust–gas dynamics in stratified disks before any strong clumping occurs. Consequently, our results confirm that in the saturated state, the streaming turbulence in stratified simulations behaves similarly to that in unstratified simulations for the parameter values explored here.}, archive = {J_ApJ}, author = {Jeonghoon Lim and Stanley A. Baronett and Jacob B. Simon and Chao-Chin Yang and Debanjan Sengupta and Orkan M. Umurhan and Wladimir Lyra}, doi = {10.3847/1538-4357/ae01a6}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {12}, shortjournal = {The Astrophys. J.}, title = {Bridging unstratified and stratified simulations of the streaming instability for τs = 0.1 grains}, volume = {993}, year = {2025}, }
• (2025). A stellar dynamical mass for the central black hole in MCG–06-30-15. ApJ, 993(1), 11. (www)

  @article{ , abstract = {We present the stellar dynamical (SD) mass of the central black hole in the nearby Seyfert galaxy MCG–06-30-15 using the Schwarzschild orbit-superposition method implemented in the open-source code FORSTAND . We obtained spatially resolved K -band nuclear stellar spectra for this galaxy with SINFONI on the Very Large Telescope. We extracted the bulk stellar kinematics using Gauss–Hermite (GH) parameterization of the line-of-sight velocity distributions. A multicomponent surface-brightness profile of the galaxy was determined from a Hubble Space Telescope medium-band V image. Our best-fit models indicate a black hole mass of M BH = (4.4 ± 1.4) × 10 7 M ⊙ and a stellar mass-to-light ratio of M / L = (3.0 ± 0.3) M ⊙ / L ⊙ , within 1 σ confidence intervals. Our constraint on M BH agrees with an upper limit on the mass from stellar dynamics based on the Jeans anisotropic modeling method, but is ∼10 times larger than the reported mass from reverberation mapping (RM). However, our best-fit M BH may be systematically biased high due to the counterrotating disk in the nucleus of MCG–06-30-15 and the inability of the GH parameterization to fully describe such a complicated set of stellar kinematics. In addition, a dynamical M BH value depends heavily on the assumed source distance, which is not yet accurately constrained for this galaxy. MCG–06-30-15 is only the fourth galaxy in which we can compare M BH from SD modeling with that from RM. A direct comparison of M BH allows us to identify and investigate the possible sources of bias associated with different mass measurement techniques, which may influence our understanding of black hole and galaxy coevolution across cosmological timescales.}, archive = {J_ApJ}, author = {Nabanita Das and Misty C. Bentz and Eugene Vasiliev and Monica Valluri and Christopher A. Onken and Sandra. I. Raimundo and Marianne Vestergaard}, doi = {10.3847/1538-4357/ae03a8}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {11}, shortjournal = {The Astrophys. J.}, title = {A stellar dynamical mass for the central black hole in MCG–06-30-15}, volume = {993}, year = {2025}, }
• (2025). Assessing the geoeffectiveness of stream interaction regions through physically interpretable machine learning. ApJ, 993(1), 10. (www)

  @article{ , abstract = {Stream interaction regions (SIRs) are common solar wind structures that mainly drive moderate geomagnetic storms, especially during the declining and minimum phases of the solar cycle. Despite substantial progress in identifying their solar wind drivers, predicting SIR geoeffectiveness remains challenging due to the nonlinear and multivariate nature of solar wind–magnetosphere coupling. In this study, we apply an interpretable machine learning framework based on a Support Vector Machine (SVM) classifier to evaluate the geoeffectiveness of 879 SIR events from 1995 to 2019. A comprehensive feature set is constructed using OMNI solar wind data, incorporating interplanetary magnetic field (IMF) components, plasma parameters, and event-level statistical descriptors, including pre- and post-event conditions. A two-step feature reduction strategy, combining Fisher score ranking with grid search optimization, is used to identify an optimal subset of input variables. The SVM model achieves a True Skill Statistic of 0.80 and an F1-score of 0.81 on the geoeffective class (Dst < –50 nT), demonstrating strong performance in identifying moderate and stronger geomagnetic storms. SHapley Additive exPlanations values and Uniform Manifold Approximation and Projection visualization are employed to interpret and validate the model’s behavior. The analysis reveals that features related to the duration of southward IMF, the solar wind electric field, and IMF Bz components play dominant roles in the model’s decision-making, consistent with known reconnection-driven energy transfer processes. These results highlight the capability of classical machine learning models, coupled with physically meaningful feature engineering and interpretability methods, to support space weather research and improve understanding of SIR-driven geomagnetic activity.}, archive = {J_ApJ}, author = {Yudong Ye and Jiajia Liu and Yongqiang Hao and Jun Cui and Xueshang Feng}, doi = {10.3847/1538-4357/ae0454}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {10}, shortjournal = {The Astrophys. J.}, title = {Assessing the geoeffectiveness of stream interaction regions through physically interpretable machine learning}, volume = {993}, year = {2025}, }
• (2025). Variations of the vector magnetic structures in the solar polar regions observed by hinode. ApJ, 993(1), 9. (www)

  @article{ , abstract = {Using the polar vector magnetic field data observed by Hinode from 2012 to 2021, we study the long-term variations of the magnetic flux, the flux proportion of different polarities, and the magnetic inclination with respect to the local normal in the solar polar regions above 70° latitude during solar cycle 24. In both polar regions, after the polarity reversal, the unsigned magnetic fluxes of the dominant polarity increased to a peak of about 1.3 × 10 22 Mx during the solar minimum, while those of the nondominant polarity remained stable at approximately 0.5 × 10 22 Mx. The proportions of the dominant polarity flux in the total flux in both polar regions increased to more than 70% at the solar minimum. These results reveal that the total magnetic flux and the number of open field lines in solar cycle 24 were larger than those in solar cycle 23, and also imply the existence of a local dynamo in polar regions. After the polarity reversal, the magnetic inclination of the dominant polarity fields decreased, indicating that the stronger the dominant polarity field, the more vertical the field lines. The inclination angle decreased with the increase of the threshold of radial magnetic flux density, revealing a fanning-out structure of the polar magnetic patches.}, archive = {J_ApJ}, author = {Shuhong Yang and Chunlan Jin and Qiao Song and Yuzong Zhang and Yin Li and Yijun Hou and Ting Li and Guiping Zhou and Yuanyong Deng and Jingxiu Wang}, doi = {10.3847/1538-4357/ae0b61}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {9}, shortjournal = {The Astrophys. J.}, title = {Variations of the vector magnetic structures in the solar polar regions observed by hinode}, volume = {993}, year = {2025}, }
• (2025). Tracing planetary accretion in a 3 gyr old hydrogen-rich white dwarf: The extremely polluted atmosphere of LSPM j0207+3331. ApJ, 993(1), 8. (www)

  @article{ , abstract = {We report the detection of 13 heavy elements (Na, Mg, Al, Si, Ca, Ti, Cr, Mn, Fe, Co, Ni, Cu, and Sr) in the photosphere of LSPM J0207+3331, a ∼3 Gyr old hydrogen-rich white dwarf with an effective temperature comparable to that of the Sun. Upper limits on carbon, obtained through the absence of molecular CH, suggest accretion from a carbon-volatile-depleted source. The accreted parent body exhibits slight deficits of Mg and Si relative to Fe but otherwise bulk Earth-like abundance patterns; a reasonable interpretation is that LSPM J0207+3331 is accreting a massive differentiated rocky body that had a core mass fraction higher than the Earth’s. The high level of pollution indicates that substantial accretion events can still occur even after 3 Gyr of cooling. We also detect weak Ca ii H & K line core emission, making this only the second known isolated polluted white dwarf to exhibit this phenomenon and suggesting the presence of additional physical processes in or above the upper atmosphere. Our analysis also highlights the critical importance of including heavy elements in the model atmosphere structure calculations for highly polluted hydrogen-rich white dwarfs. Neglecting their contribution significantly impacts the inferred thermodynamic structure, leading to inaccuracies in derived stellar parameters. Finally, we show that the observed 11.6 μ m infrared excess can be explained by a single silicate dust disk rather than a two-ring disk model.}, archive = {J_ApJ}, author = {Érika Le Bourdais and Patrick Dufour and Carl Melis and Beth L. Klein and Laura K. Rogers and Antoine Bédard and John Debes and Ashley Messier and Alycia J. Weinberger and Siyi Xu}, doi = {10.3847/1538-4357/ae0ace}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {8}, shortjournal = {The Astrophys. J.}, title = {Tracing planetary accretion in a 3 gyr old hydrogen-rich white dwarf: The extremely polluted atmosphere of LSPM j0207+3331}, volume = {993}, year = {2025}, }
• (2025). Multispacecraft observations of 2022 february 8 prominence cavity eruption. ApJ, 993(1), 7. (www)

  @article{ , abstract = {Helmet streamers are common structures that shape the corona at the largest scales, as observed in eclipse and white-light images. Helmet streamers overlie one cavity embedding a prominence channel and are surrounded by an open field of opposite-polarity coronal holes. In this study, we present multispacecraft observations of a spectacular prominence-cavity eruption from the southeastern solar limb accompanied by a geoeffective coronal mass ejection (CME), observed by the Solar Dynamics Observatory, Solar Terrestrial Relations Observatory, Solar Orbiter, Advanced Composition Explorer, and Wind . We produce 3D magnetic field configurations before and during the eruption using the flux-rope insertion method and magnetofrictional relaxation that are consistent with the observations. We also performed a differential emission measure analysis to study the thermal structure of the helmet streamer prominence-cavity region before and after the eruption. We note that because of the considerable length of the prominence, it was possible to capture the eruption using in situ measurements by multiple spacecraft. Moreover, our multispacecraft in situ analysis shows that the CME propagating in the precondition medium varies as a function of longitude in the heliosphere.}, archive = {J_ApJ}, author = {Nishu Karna and Mari Paz Miralles}, doi = {10.3847/1538-4357/ae07d1}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {7}, shortjournal = {The Astrophys. J.}, title = {Multispacecraft observations of 2022 february 8 prominence cavity eruption}, volume = {993}, year = {2025}, }
• (2025). Effects of dark matter self-interactions on sagittarius and its stream. ApJ, 993(1), 6. (www)

  @article{ , abstract = {This work explores how assumptions regarding the particle-physics nature of dark matter can alter the evolution of the Sagittarius (Sgr) dwarf spheroidal galaxy and its expansive stellar stream. We run a large suite of N -body simulations to model the infall of a spherically symmetric Sgr-like dwarf, exploring how the presence of dark matter self-interactions impacts its evolution. For a scattering cross section of σ / m χ = 30 cm 2 g −1 (at orbital velocity scales), these interactions result in significantly less stellar mass and little to no dark matter bound to the progenitor at the present day. To isolate the cause of this mass loss, we introduce a novel technique for controlling which pairs of dark matter simulation particles can interact. This enables us to identify ram-pressure evaporation—the scattering of satellite and host dark matter particles—as the primary source of the enhanced mass loss. The rapid disintegration of the Sgr progenitor when self-interactions are allowed alters some key properties of the resulting stellar stream, most dramatically suppressing the presence of a “spur” on the apocenter of the trailing stream arm that correlates with the mass of the satellite at last pericenter. We demonstrate how the effects on the Sgr system scale with the particular choice of self-interaction cross section, which affects the degree of ram-pressure evaporation. These findings generalize beyond the Sgr system, underscoring that dwarf stellar streams and dwarf galaxies with close passages may serve as sensitive probes for dark matter self-interactions.}, archive = {J_ApJ}, author = {Connor Hainje and Oren Slone and Mariangela Lisanti and Denis Erkal}, doi = {10.3847/1538-4357/adfed8}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {6}, shortjournal = {The Astrophys. J.}, title = {Effects of dark matter self-interactions on sagittarius and its stream}, volume = {993}, year = {2025}, }
• (2025). The variable radio emission of v830 tau and its putative planet. ApJ, 993(1), 5. (www)

  @article{ , abstract = {We report on the first moderate-length timescale observations of a young stellar object at microwave frequencies. V830 Tau was monitored over the course of 8 days with the Karl G. Jansky Very Large Array at a frequency range of 4–8 GHz. Previous brief radio observations of this purported planet-hosting star indicated a radio-bright source with sparse evidence of dramatic intensity changes. Our observations confirm variability larger than a factor of 5 over the 8 days, with closer-spaced data indicating a long-lived flare event spanning multiple days. We discuss a hypothesis that the large, long-duration radio flare may be produced as a result of magnetospheric interaction between the star and its purported planet, using multiyear monitoring of a few active binary systems with the Green Bank Interferometer to augment our discussion. Although we cannot disentangle the effect of the large stellar surface area from any effects of orbital separation, the disputed star–planet system would have a large amount of power generated from the stretching and breaking of magnetic fields. If this long-duration flare behavior repeats with additional data on timescales close to the planetary orbital period, microwave signatures of interacting magnetospheres could be a new observational tool to confirm the existence of planets around young, magnetically active stars.}, archive = {J_ApJ}, author = {Rachel A. Osten and Scott J. Wolk}, doi = {10.3847/1538-4357/ae03b7}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {5}, shortjournal = {The Astrophys. J.}, title = {The variable radio emission of v830 tau and its putative planet}, volume = {993}, year = {2025}, }
• (2025). Neutral gas phase distribution from h i morphology: Phase separation with scattering spectra and variational autoencoders. ApJ, 993(1), 4. (www)

  @article{ , abstract = {Unraveling the multiphase structure of the diffuse interstellar medium as traced by neutral hydrogen (H i ) is essential to understanding the lifecycle of the Milky Way. However, H i phase separation is a challenging and underconstrained problem. The neutral gas phase distribution is often inferred from the spectral line structure of H i emission. In this work, we develop a data-driven phase-separation method that extracts H i phase structure solely from the spatial morphology of H i emission intensity structures. We combine scattering spectra (SS) statistics with a Gaussian-mixture variational autoencoder model to (1) derive an interpretable statistical model of different H i phases from their multiscale morphological structures, and (2) we use this model to decompose the 2D channel maps of GALFA-H i emission in diffuse high-latitude (∣ b ∣ > 30°) regions over narrow velocity channels (Δ v = 3 km s −1 ) into cold neutral medium (CNM), warm neutral medium (WNM), and noise components. We integrate our CNM map over velocity channels to compare it to an existing map produced by a spectrum-based method. We find that the two maps are highly correlated, but ours recovers more spatially coherent structures at small scales. Our work illustrates and quantifies a clear physical connection between the H i morphology and H i phase structure, and it unlocks a new avenue for improving future phase-separation techniques by making use of both H i spectral and spatial information to decompose H i in 3D position–position–velocity space. These results are consistent with a physical picture where processes that drive H i phase transitions also shape the morphology of H i gas, imprinting a sparse, filamentary CNM that forms out of a diffuse, extended WNM.}, archive = {J_ApJ}, author = {Minjie Lei and S. E. Clark and Rudy Morel and E. Allys and Iryna S. Butsky and Caleb Redshaw and Drummond B. Fielding}, doi = {10.3847/1538-4357/ae044a}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {4}, shortjournal = {The Astrophys. J.}, title = {Neutral gas phase distribution from h i morphology: Phase separation with scattering spectra and variational autoencoders}, volume = {993}, year = {2025}, }
• (2025). Seismic oscillations excited by giant impacts in directly imaged giant planets. ApJ, 993(1), 3. (www)

  @article{ , abstract = {The radii and masses of many giant exoplanets imply their interiors each contain more than ∼100 M ⊕ of solids. A large metal content may arise when a giant planet grows by colliding and merging with multiple ∼10 M ⊕ solid cores. Here we show that a giant impact with a young gas giant excites long-lived seismic oscillations that can be detected photometrically. The mode lifetimes are close to the planet’s Kelvin–Helmholtz time, a significant fraction of a young planet’s age. The oscillation periods lie between tens of minutes to an hour, and the variability amplitudes can exceed a percent for several million years. Beta Pictoris b is a young super-Jupiter known to be highly metal-enriched. If a Neptune-mass (17 M ⊕ ) body impacted β Pictoris b in the past ∼9–18 Myr, the planet could still be ringing with a percent-level photometric variability measurable with JWST.}, archive = {J_ApJ}, author = {J. J. Zanazzi and Eugene Chiang and Yifan Zhou}, doi = {10.3847/1538-4357/ae04ec}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {3}, shortjournal = {The Astrophys. J.}, title = {Seismic oscillations excited by giant impacts in directly imaged giant planets}, volume = {993}, year = {2025}, }
• (2025). Aeos: The impact of population III initial mass function and star-by-star models in galaxy simulations. ApJ, 993(1), 2. (www)

  @article{ , abstract = {We explore the effect of variations in the Population III initial mass function (IMF) and star-by-star feedback on early galaxy formation and evolution using the A eos simulations. We compare simulations with two different Population III IMFs: M char = 10 M ⊙ and {M}_{\max }=100\,{M}_{\odot } (Aeos10) and M char = 20 M ⊙ and {M}_{\max }=300\,{M}_{\odot } (Aeos20). Aeos20 produces significantly more ionizing photons, ionizing 30% of the simulation volume by z ≈ 14, compared to 9% in Aeos10. This enhanced ionization suppresses galaxy formation on the smallest scales. Differences in Population III IMF also affect chemical enrichment. Aeos20 produces Population II stars with higher abundances, relative to iron, of light and α -elements, a stronger odd–even effect, and a higher frequency of carbon-enhanced metal-poor stars. The abundance scatter between different Population II galaxies dominates the differences due to Population III IMF, though, implying a need for a larger sample of Population II stars to interpret the impact of Population III IMF on early chemical evolution. We also compare the A eos simulations to traditional simulations that use single stellar population particles. We find that star-by-star modeling produces a steeper mass–metallicity relation due to less bursty feedback. These results highlight the strong influence of the Population III IMF on early galaxy formation and chemical evolution, emphasizing the need to account for IMF uncertainties in simulations and the importance of metal-poor Population II stellar chemical abundances when studying the first stars.}, archive = {J_ApJ}, author = {Kaley Brauer and Jennifer Mead and John H. Wise and Greg L. Bryan and Mordecai-Mark Mac Low and Alexander P. Ji and Andrew Emerick and Eric P. Andersson and Anna Frebel and Benoit Côté}, doi = {10.3847/1538-4357/ae06a4}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {2}, shortjournal = {The Astrophys. J.}, title = {Aeos: The impact of population III initial mass function and star-by-star models in galaxy simulations}, volume = {993}, year = {2025}, }
• (2025). Cumulative proton right-handed instabilities in the young solar wind observed by PSP. ApJ, 993(1), 1. (www)

  @article{ , abstract = {We present a detailed linear analysis of right-handed (RH) proton instabilities in beaming bi-Maxwellian/bi-Kappa plasma representative of young solar wind conditions currently explored by the Parker Solar Probe. At lower heliocentric distances, ion (proton) beams are more dense, and the associated wave fluctuations are predominantly RH polarized, strongly suggesting the presence of proton-beam plasma instabilities to explain not only the enhanced fluctuations but also the subsequent particle diffusion in energy and pitch angle. The study systematically investigates the cumulative effects of beam drift velocity and temperature anisotropies on the ion–ion resonant and proton firehose instabilities. By examining the variations in maximum growth rates, resonant factors, and instability thresholds across a broad range of plasma parameters, including beam and core anisotropies, density ratios, plasma beta, and suprathermal populations, this work identifies the key regimes where instabilities are enhanced or suppressed. The influence of suprathermal ions and electrons, modeled using Kappa distributions, is shown to significantly extend the unstable parameter space. Electron temperature anisotropy is also found to strongly modify the growth rates of these instabilities by changing their resonance conditions with beaming particles. This parametric study provides comprehensive guidance for future quasilinear or simulation studies by identifying the most physically relevant and numerically effective regimes for these instabilities in the solar wind and space plasmas.}, archive = {J_ApJ}, author = {Shaaban M. Shaaban and M. Lazar and H. Fichtner and R. A. López and S. Poedts}, doi = {10.3847/1538-4357/ae09ac}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {1}, shortjournal = {The Astrophys. J.}, title = {Cumulative proton right-handed instabilities in the young solar wind observed by PSP}, volume = {993}, year = {2025}, }
• (2025). Erratum: “Galactic cosmic rays in the local interstellar medium: Voyager 1 observations and model results” (2016, ApJ, 831, 18). ApJ, 992(2), 218. (www)

  @article{ , archive = {J_ApJ}, author = {A. C. Cummings and E. C. Stone and B. C. Heikkila and N. Lal and W. R. Webber and G. Jóhannesson and I. V. Moskalenko and E. Orlando and T. A. Porter}, doi = {10.3847/1538-4357/ae0c98}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {218}, shortjournal = {The Astrophys. J.}, title = {Erratum: “Galactic cosmic rays in the local interstellar medium: Voyager 1 observations and model results” (2016, ApJ, 831, 18)}, volume = {992}, year = {2025}, }
• (2025). Erratum: “One relation for all wavelengths: The far-ultraviolet to mid-infrared milky way spectroscopic R(V)-dependent dust extinction relationship” (2023, ApJ, 950, 86). ApJ, 992(2), 217. (www)

  @article{ , archive = {J_ApJ}, author = {Karl D. Gordon and Geoffrey C. Clayton and Marjorie Decleir and E. L. Fitzpatrick and Derck Massa and Karl A. Misselt and Erik J. Tollerud}, doi = {10.3847/1538-4357/ae0cca}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {217}, shortjournal = {The Astrophys. J.}, title = {Erratum: “One relation for all wavelengths: The far-ultraviolet to mid-infrared milky way spectroscopic R(V)-dependent dust extinction relationship” (2023, ApJ, 950, 86)}, volume = {992}, year = {2025}, }
• (2025). Cool dark gas in cygnus x: The first large-scale mapping of low-frequency carbon recombination lines. ApJ, 992(2), 216. (www)

  @article{ , abstract = {Understanding the transition from atomic gas to molecular gas is critical to explain the formation and evolution of molecular clouds. However, the gas phases involved, cold H i and CO-dark molecular gas, are challenging to directly observe and physically characterize. We observed the Cygnus X star-forming complex in carbon radio recombination lines (CRRLs) at 274–399 MHz with the Green Bank Telescope at 48 ^{\prime} (21 pc) resolution. Of the 30 deg 2 surveyed, we detect line-synthesized C273 α emission from 24 deg 2 and produce the first large-area maps of low-frequency CRRLs, which likely originate in CO-dark molecular gas. The morphology of the C273 α emission reveals arcs, ridges, and extended possibly sheet-like gas, which are often found on the outskirts of CO emission. We find a correlation between velocity-integrated C273 α and the 8 μ m intensity with a power-law slope of 1.3 ± 0.2. We interpret the relation as the dependence of cool dark gas emission on the far-ultraviolet radiation field, G 0 ≈ 40−160. We determine the typical angular separation between C273 α and 13 CO emission to be 12 pc. Velocity differences between C273 α and 13 CO are apparent throughout the region and have a typical value of 2.9 km s −1 . We estimate gas densities of n ≈ 20−900 cm −3 with a nominal n ≈ 400 cm −3 in the C + /H 2 layer. The evolution of the C273 α gas seems to be dominated by turbulent pressure, with a characteristic timescale to form H 2 of about 2.6 Myr. These observations underline the richness of low-frequency CRRLs to provide revelatory insights into the characteristics of (CO-)dark gas and the evolution of molecular gas.}, archive = {J_ApJ}, author = {Kimberly L. Emig and Pedro Salas and Loren D. Anderson and D. Anish Roshi and Lars Bonne and Alberto D. Bolatto and Isabelle A. Grenier and Rebecca C. Levy and Dylan J. Linville and Matteo Luisi and M. Riley Owens and J. Poojapriyatharsheni and Nicola Schneider and Luigi Tibaldo and Alexander G. G. M. Tielens and Stefanie K. Walch and Glenn J. White}, doi = {10.3847/1538-4357/adfa17}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {216}, shortjournal = {The Astrophys. J.}, title = {Cool dark gas in cygnus x: The first large-scale mapping of low-frequency carbon recombination lines}, volume = {992}, year = {2025}, }
• (2025). Potassium abundances in extremely metal poor stars: Implications for nucleosynthesis in the final stages of massive star evolution∗. ApJ, 992(2), 215. (www)

  @article{ , abstract = {We present a potassium (K) abundance analysis in extremely metal-poor (EMP) stars based on high-resolution ( R ∼ 60,000) spectra obtained with the High Dispersion Spectrograph on the Subaru Telescope, covering the K i resonance lines at 766 and 769 nm. One-dimensional local thermodynamic equilibrium (LTE) abundances of K and other elements, including Na, Mg, Ca, Ti, Cr, and Ni, were derived using spectral synthesis. Non-LTE (NLTE) corrections were applied to the K abundances by interpolating a precomputed grid of corrections based on stellar parameters and the LTE K abundance. We detected K i lines in seven stars with [Fe/H] < –3.0 and derived upper limits for other stars in the same metallicity regime, making this sample well-suited for investigating the nucleosynthesis origins of K in the early Universe. We found that the [K/Fe] and [K/Ca] ratios of the seven stars are enhanced relative to the solar value, with a scatter of ∼0.1 dex, as small as the typical measurement uncertainty. Under the assumption that each star formed from gas purely enriched by a single or a few massive star’s supernova, the small scatter in [K/Fe] and [K/Ca], contrasted with the ∼0.7 dex scatter in [Na/Mg] ratios (after NLTE correction), suggests that the production of K in massive stars or their supernovae is independent of the processes that drive the Na/Mg variation. These findings demonstrate that K abundances in EMP stars, and their correlations with other elemental abundances, can serve as sensitive tracers of the physical mechanisms governing the final evolutionary stages of massive stars and their supernova explosions.}, archive = {J_ApJ}, author = {Miho N. Ishigaki and Nozomu Tominaga and Wako Aoki and Shinya Wanajo and Tomoya Takiwaki and Ko Nakamura and Nobuyuki Iwamoto and Ken’ichi Nomoto and Chiaki Kobayashi}, doi = {10.3847/1538-4357/ae00b8}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {215}, shortjournal = {The Astrophys. J.}, title = {Potassium abundances in extremely metal poor stars: Implications for nucleosynthesis in the final stages of massive star evolution∗}, volume = {992}, year = {2025}, }
• (2025). Mitigating eddington and malmquist biases in latent-inclination inference of the Tully–Fisher relation. ApJ, 992(2), 214. (www)

  @article{ , abstract = {The Tully–Fisher relation is a vital distance indicator, but its precise inference is challenged by selection bias, statistical bias, and uncertain inclination corrections. This study presents a Bayesian framework that simultaneously addresses these issues. To eliminate the need for individual inclination corrections, inclination is treated as a latent variable with a known probability distribution. To correct for the distance-dependent Malmqvist bias arising from sample selection, the model incorporates Gaussian scatter in the dependent variable, the distribution of the independent variable, and the observational selection function into the data likelihood. To mitigate the statistical bias, termed the “general Eddington bias,” caused by Gaussian scatter and the nonuniform distribution of the independent variable, two methods are introduced: (1) analytical bias corrections applied to the dependent variable before likelihood computation, and (2) a dual-scatter model that accounts for Gaussian scatter in the independent variable within the likelihood function. The effectiveness of these methods is demonstrated using simulated data sets. By rigorously addressing selection and statistical biases in a latent-variable regression analysis, this work provides a robust approach for unbiased distance estimates from standardizable candles, which is critical for improving the accuracy of Hubble constant determinations.}, archive = {J_ApJ}, author = {Hai Fu}, doi = {10.3847/1538-4357/adfa2c}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {214}, shortjournal = {The Astrophys. J.}, title = {Mitigating eddington and malmquist biases in latent-inclination inference of the Tully–Fisher relation}, volume = {992}, year = {2025}, }
• (2025). Structure and dynamics of the young massive star cluster westerlund 1. ApJ, 992(2), 213. (www)

  @article{ , abstract = {We present a structural and dynamical analysis of the young massive star cluster Westerlund 1 (Wd1). Using multiepoch Hubble Space Telescope observations, we measure the proper motions of 10,346 stars and present an unprecedented determination of cluster membership probability. We then determine the color membership after correcting for extinction. The stellar density map weighted by the membership probability and completeness correction displays a spatial elongation aligned with the Galactic plane with a high eccentricity of 0.71. The radial stellar density profile shows a decreasing core radius with increasing mass, indicative of weak but detectable mass segregation. Quantitatively, the measured mass segregation ratio is Λ MSR = 1.11 ± 0.11, only above unity by 1 σ . Building on the structural modeling along with a suite of stellar evolutionary and atmospheric models, we fit the cluster age and distance in two color–magnitude diagrams, concluding that Wd1 is approximately 7.45 ± 0.53 Myr old and at a distance of 3.7 ± 0.1 kpc, with a degeneracy in the posterior which is compatible with the literature values. We measure a 1D velocity dispersion of 4.13 ± 0.13 km s −1 , indicating a subvirialized state. The crossing time is 0.30 Myr and the relaxation time is 0.26 Gyr. Given the age of Wd1, we expect dynamical mass segregation for stars more massive than 12 M ⊙ , which accounts for the minor mass segregation observed in the mass range of 1.12–15.21 M ⊙ in this work. This suggests that the mass segregation in Wd1 is more likely a dynamical effect.}, archive = {J_ApJ}, author = {Lingfeng Wei and Peter C. Boyle and Jessica R. Lu and Matthew W. Hosek and Quinn M. Konopacky and Richard G. Spencer and Dongwon Kim and Nicholas Z. Rui and Max Service and D. B. Huang and Jay Anderson}, doi = {10.3847/1538-4357/adfc60}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {213}, shortjournal = {The Astrophys. J.}, title = {Structure and dynamics of the young massive star cluster westerlund 1}, volume = {992}, year = {2025}, }
• (2025). JADES-GS-z14-1: A compact, faint galaxy at z ≈ 14 with weak metal lines from extremely deep JWST MIRI, NIRCam, and NIRSpec observations. ApJ, 992(2), 212. (www)

  @article{ , abstract = {JWST has shed light on galaxy formation and metal enrichment within 300 Myr of the Big Bang. While luminous galaxies at z > 10 often show significant [O iii ] λλ 4959, 5007 emission lines, it remains unclear whether such features are prevalent among fainter, more typical galaxies due to observational limits. We present deep imaging and spectroscopy of JADES-GS-z14-1 at {z}_{{\rm{spec}}}=13.8{6}_{-0.05}^{+0.04} , currently the faintest spectroscopically confirmed galaxy at z ≈ 14. It serendipitously received 70.7 hr of MIRI/F770W imaging in the JWST Advanced Deep Extragalactic Survey (JADES), the deepest MIRI exposure for any high-redshift galaxy to date. Nonetheless, we detect only tentative F770W emission of 7.9 ± 2.8 nJy at 2.8 σ significance, constraining the total equivalent width of [O iii ] λλ 4959, 5007 + H β to 52{0}_{-380}^{+400} Å, weaker than most z > 10 galaxies with MIRI detections. This source is unresolved across 16 NIRCam bands, implying a physical radius ≲50 pc. NIRSpec/PRISM spectroscopy totaling 56 hr reveals no rest-frame ultraviolet emission lines above 3 σ . Stellar population synthesis suggests a stellar mass ∼4 × 10 7 M ⊙ and a star formation rate ∼2 M ⊙ yr −1 . The absence of strong metal emission lines despite intense star formation suggests a gas-phase metallicity below 10% solar and potentially a high escape fraction of ionizing photons. These deep observations provide rare constraints on faint, early galaxies, tracing the onset of chemical enrichment and ionization in the early Universe.}, archive = {J_ApJ}, author = {Zihao Wu and Daniel J. Eisenstein and Benjamin D. Johnson and Peter Jakobsen and Stacey Alberts and Santiago Arribas and William M. Baker and Andrew J. Bunker and Stefano Carniani and Stéphane Charlot and Jacopo Chevallard and Mirko Curti and Emma Curtis-Lake and Francesco D’Eugenio and Kevin Hainline and Jakob M. Helton and Tiger Yu-Yang Hsiao and Xihan Ji and Zhiyuan Ji and Tobias J. Looser and George Rieke and Pierluigi Rinaldi and Brant Robertson and Jan Scholtz and Fengwu Sun and Sandro Tacchella and James A. A. Trussler and Christina C. Williams and Christopher N. A. Willmer and Chris Willott and Joris Witstok and Yongda Zhu}, doi = {10.3847/1538-4357/ae01a1}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {212}, shortjournal = {The Astrophys. J.}, title = {JADES-GS-z14-1: A compact, faint galaxy at z ≈ 14 with weak metal lines from extremely deep JWST MIRI, NIRCam, and NIRSpec observations}, volume = {992}, year = {2025}, }
• (2025). Revisiting the supermassive black hole mass of NGC 7052 using high spatial resolution molecular gas observed with ALMA. ApJ, 992(2), 211. (www)

  @article{ , abstract = {We present our dynamical mass constraints on the central supermassive black hole (SMBH) in the early-type galaxy NGC 7052 using high spatial-resolution observations of 12 CO(2–1) emission from the Atacama Large Millimeter/submillimeter Array (ALMA). The data were obtained during ALMA Cycle 7 and have a synthesized beam size of 0 \mathop{.}\limits^{^{\prime\prime} } 29 ×0 \mathop{.}\limits^{^{\prime\prime} } 22 (97 × 73 pc 2 ). The dynamical model yielded an SMBH mass of ≈(2.50 ±0.37 [statistical] ± 0.8 [systematic]) × 10 9 M ⊙ and a stellar I- band mass-to-light ratio of ≈4.08 ±0.23 [statistical] ± 0.4 [systematic] M ⊙ / L ⊙ , I (3 σ confidence intervals). Although our new ALMA observation has three times lower spatial resolution than previous ALMA data, it still resolves the SMBH’s sphere of influence with a spatial resolution that is 1.5 times smaller than this sphere radius. While our M BH estimate is fully consistent with the previous determination, the I -band mass-to-light ratio is lower by 10%. This difference arises from our improved galaxy mass model, which incorporates both the molecular gas distribution and the extended stellar mass in the outer regions of the galaxy, the components that were previously neglected.}, archive = {J_ApJ}, author = {Hai N. Ngo and Dieu D. Nguyen and Tinh Q. T. Le and Khue N. H. Ho and Tien H. T. Ho and Elena Gallo and Kristina Nyland and Masatoshi Imanishi and Kouichiro Nakanishi and Que T. Le and Fabio Pacucci and Eden Girma}, doi = {10.3847/1538-4357/ae0455}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {211}, shortjournal = {The Astrophys. J.}, title = {Revisiting the supermassive black hole mass of NGC 7052 using high spatial resolution molecular gas observed with ALMA}, volume = {992}, year = {2025}, }
• (2025). Distinct fe k line complexes in MAXI j1744−294 revealed by XRISM high-resolution spectroscopy. ApJ, 992(2), 210. (www)

  @article{ , abstract = {The newly discovered Galactic transient MAXI J1744−294 went into its first X-ray outburst in 2025. We study the spectral properties of this source in the 2–10 keV energy band during this outburst using X-ray data from the XRISM satellite for both of its Resolve and Xtend instruments, taken on 2025 March 3. High-resolution spectroscopy has revealed, for the first time, complex iron line features in this source, corresponding to distinct components of Fe XXV emission and Fe XXVI absorption lines. Such a detailed structure has not been reported in other low-mass X-ray binaries to date, prior to the XRISM era. Our analysis shows that the line complexes arise from two highly ionized plasmas with an ionization rate ∼10 3 erg cm s −1 with distinct turbulent velocities—one broad ( v turb ≈ 2513 km s −1 ) from hot gas at the inner accretion disk and one narrow ( v turb ≈ 153 km s −1 ) scattered by nearby photoionized gas. These results offer new insight into the reprocessing of continuum in stratified media, either in the accretion disk or winds, or both, for X-ray binaries in the soft state. The data are well described by models with spin, mass of the black hole, and accretion disk inclination 0.63–0.70, 7.9 ± 2.2 M ⊙ , and 19°–24°. The fitted spectral model parameters suggest that the source is in the soft spectral state. The source is situated in a crowded field near the Galactic center, resulting in a large hydrogen column density.}, archive = {J_ApJ}, author = {Kaushik Chatterjee and Santanu Mondal and Biswaraj Palit and Chandra B. Singh and Sujoy Kumar Nath and Mayukh Pahari and Brajesh Kumar and Wei Wang and Hsiang-Kuang Chang and Xiaowei Liu}, doi = {10.3847/1538-4357/ae07d8}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {210}, shortjournal = {The Astrophys. J.}, title = {Distinct fe k line complexes in MAXI j1744−294 revealed by XRISM high-resolution spectroscopy}, volume = {992}, year = {2025}, }
• (2025). Testing the kerr paradigm via synchrotron radiation. ApJ, 992(2), 209. (www)

  @article{ , abstract = {General relativity has been tested in weak field regimes, but strong gravity regimes are still to be verified. The strong gravity regime with synchrotron radiation has not yet been explored. The nonthermal synchrotron emission traces the magnetic field and cosmic-ray electrons. This paper presents a test of a strong gravity regime using synchrotron radiation with two different spacetime metrics: Kerr and Cardoso, Pani, and Rico (CPR). We investigate the effects of variation in model parameters such as the spin, inclination angle, magnetic field, and nonthermal spectral index of the synchrotron radiation on flux density as a function of frequency as an observable, first in the Kerr and then in the CPR spacetime. We generate mock data observations and fit the model using Bayesian inference for both spacetimes. Assuming a uniform prior, analyzed synchrotron radiation with a Bayesian approach can distinguish Kerr and CPR spacetimes by constraining spin and deformation parameters. A Gaussian prior also allows for this distinction. However, if a Gaussian prior is used for the spin while keeping the deformation parameters uniform, only the spin can be constrained, making it impossible to differentiate between Kerr and CPR spacetime.}, archive = {J_ApJ}, author = {M. Ghasemi-Nodehi and Fatemeh S. Tabatabaei and Lang Cui}, doi = {10.3847/1538-4357/ae0450}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {209}, shortjournal = {The Astrophys. J.}, title = {Testing the kerr paradigm via synchrotron radiation}, volume = {992}, year = {2025}, }
• (2025). Surface waves at switchback boundaries in the young solar wind from parker solar probe observations. ApJ, 992(2), 208. (www)

  @article{ , abstract = {Switchbacks (SBs) are localized magnetic field deflections in the solar wind, marked by abrupt changes in the magnetic field direction relative to the ambient solar wind. Observations on board Parker Solar Probe (PSP) at heliocentric distances below 50 solar radii R S showed that within SBs, perturbations in the magnetic field ( {\rm{\Delta }}{\boldsymbol{B}} ) and the bulk solar wind velocity ( {\rm{\Delta }}{\boldsymbol{V}} ) align, i.e., {\rm{\Delta }}{\boldsymbol{B}}\sim {\rm{\Delta }}{\boldsymbol{V}} , producing enhanced radial velocity spikes. In this study, we examine the characteristics of SB boundaries, with particular attention to the role of boundary shear flow instabilities (Kelvin–Helmholtz instability; KHI) for surface wave phenomena based on the in situ magnetic field, plasma speed, and plasma density measurements from PSP. The results indicate that SB boundaries can be unstable for generating KHI-driven surface waves, suggesting that the wave activity observed at SB boundaries is caused by shear flow instabilities. In addition, the continued development of KHI may lead to boundary erosion, contributing to the radial evolution of SBs via structural weakening or broadening. However, when {\rm{\Delta }}{\boldsymbol{B}} and {\rm{\Delta }}{\boldsymbol{V}} are closely aligned, the boundary remains stable unless the velocity shear significantly exceeds the magnetic shear. Since the observed velocity shear typically ranges from 40% to 90% of magnetic shear, the instability condition is generally not satisfied. Thus, the configuration leading to the instability arises from deviations from precise alignment of {\rm{\Delta }}{\boldsymbol{B}} and {\rm{\Delta }}{\boldsymbol{V}} in the young solar wind, and the release of the KHI presumably leads to the formation of the {\rm{\Delta }}{\boldsymbol{B}} and {\rm{\Delta }}{\boldsymbol{V}} alignment observed at SB boundaries located at 35–55 R S .}, archive = {J_ApJ}, author = {Kyung-Eun Choi and Oleksiy V. Agapitov and Nina Bizien and Thierry Dudok de Wit and Lucas Colomban}, doi = {10.3847/1538-4357/ae0b65}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {208}, shortjournal = {The Astrophys. J.}, title = {Surface waves at switchback boundaries in the young solar wind from parker solar probe observations}, volume = {992}, year = {2025}, }
• (2025). Evaluating the contributions of tianwen-1 orbiter tracking data to the mars gravity field modeling. ApJ, 992(2), 207. (www)

  @article{ , abstract = {Mars gravity field models are critical data sets for studying the planet’s internal structure. Currently, Mars gravity field determination is primarily based on modeling of tracking data from spacecraft such as Mars Reconnaissance Orbiter, Mars Odyssey, and Mars Global Surveyor. The Tianwen-1 mission has now been operational in orbit for over 3 yr. In this study, we construct a degree and order 120 gravity field model using Tianwen-1 spacecraft tracking data from 2021 June to 2024 October and perform a data fusion with the MRO120D gravity field model. Thereafter, we evaluate the contribution of Tianwen-1 tracking data to the improvement of the Martian gravity field modeling. Results indicate that the tracking data from Tianwen-1 provide limited enhancement to the low-degree terms of the gravity field. The relative errors in low-degree terms up to degree 10 of the fused model range from 10 −6 to 10 −4 , and the formal uncertainties up to degree 6 are consistent with those of MRO120F model. The maximum difference in gravity anomalies at the Mars surface reaches 4.5 mGal, while the maximum discrepancy in gravity anomaly errors is approximately 0.65 mGal. The orbit determination performance for the Tianwen-1 spacecraft remains consistent between the two models. Currently, the accuracy improvement in the Martian static gravity field modeling achieved through Earth-based tracking data is relatively modest. Future significant advancements in Martian static gravity field modeling should focus on novel measurement techniques, such as satellite-to-satellite tracking, gravity gradiometry, and an accelerometer on board the spacecraft.}, archive = {J_ApJ}, author = {Chongyang Wang and Jianguo Yan and Shanhong Liu and Shangbiao Sun and Wanling Yang and Jianfeng Cao and Denggao Qiu and Xie Li and Jean-Pierre Barriot}, doi = {10.3847/1538-4357/ae0e22}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {207}, shortjournal = {The Astrophys. J.}, title = {Evaluating the contributions of tianwen-1 orbiter tracking data to the mars gravity field modeling}, volume = {992}, year = {2025}, }
• (2025). Morphology of 35 repeating fast radio burst sources at microsecond time scales with CHIME/FRB. ApJ, 992(2), 206. (www)

  @article{ , abstract = {The Canadian Hydrogen Intensity Mapping Experiment Fast Radio Burst (CHIME/FRB) project has discovered the most repeating FRB sources of any telescope. However, most of the physical conclusions derived from this sample are based on data with a time resolution of ∼1 ms. In this work, we present for the first time a morphological analysis of the raw voltage data for 124 bursts from 35 of CHIME/FRB's repeating sources. We do not find any significant correlations among fluence, dispersion measure (DM), burst rate, and burst duration. Performing the first large-scale morphological comparison at timescales down to microseconds between our repeating sources and 125 nonrepeating FRBs, we find that repeaters are narrower in frequency and broader in duration than nonrepeaters, supporting previous findings. However, we find that the duration-normalized sub-burst widths of the two populations are consistent, possibly suggesting a shared physical emission mechanism. Additionally, we find that the spectral fluences of the two are consistent. When combined with the larger bandwidths and previously found larger DMs of nonrepeaters, this suggests that nonrepeaters may have higher intrinsic specific energies than repeating FRBs. We do not find any consistent increase or decrease in the DM (⪅1 pc cm −3 yr −1 ) and scattering timescales (⪅2 ms yr −1 ) of our sources over ∼2–4 yr periods.}, archive = {J_ApJ}, author = {Alice P. Curtin and Ketan R. Sand and Ziggy Pleunis and Naman Jain and Victoria Kaspi and Daniele Michilli and Emmanuel Fonseca and Kaitlyn Shin and Kenzie Nimmo and Charanjot Brar and Fengqiu Adam Dong and Gwendolyn M. Eadie and B. M. Gaensler and Antonio Herrera-Martin and Adaeze L. Ibik and Ronniy C. Joseph and Jane Kaczmarek and Calvin Leung and Robert Main and Kiyoshi W. Masui and Ryan Mckinven and Juan Mena-Parra and Cherry Ng and Ayush Pandhi and Aaron B. Pearlman and Masoud Rafiei-Ravandi and Mawson W. Sammons and Paul Scholz and Kendrick Smith and Ingrid Stairs}, doi = {10.3847/1538-4357/adf844}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {206}, shortjournal = {The Astrophys. J.}, title = {Morphology of 35 repeating fast radio burst sources at microsecond time scales with CHIME/FRB}, volume = {992}, year = {2025}, }
• (2025). Testing f(R) gravity from cosmic shear measurements. ApJ, 992(2), 205. (www)

  @article{ , abstract = {In this work, we perform a detailed analysis to constrain the Hu–Sawicki f ( R ) gravity model, using cosmic shear data from three prominent Stage-III weak lensing surveys: Dark Energy Survey Year 3, KiDS-1000, and Hyper Suprime-Cam Year 3. To accurately model the nonlinear matter clustering in the analysis of cosmic shear signals, we employ FREmu , a recently developed power spectrum emulator for the f ( R ) gravity trained on the Quijote-MG simulations. This emulator achieves precise predictions, limiting the errors to 5% on scales of 0.009 h Mpc −1 < k < 0.5 h Mpc −1 . Our findings reveal that cosmic shear data alone impose only weak constraints on the f ( R ) parameter {{\mathrm{log}}_{10}}\,| {f}_{{R}_{0}}| . To improve these constraints, we incorporate state-of-the-art external observations, including data from the cosmic microwave background and baryon acoustic oscillations. The inclusion of these external data sets significantly enhances the constraints, yielding an upper limit of {{\mathrm{log}}_{10}}\,| {f}_{{R}_{0}}| \lt -4.98 at the 95% confidence level.}, archive = {J_ApJ}, author = {Jiachen Bai and Jun-Qing Xia and Gong-Bo Zhao}, doi = {10.3847/1538-4357/ae07c4}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {205}, shortjournal = {The Astrophys. J.}, title = {Testing f(R) gravity from cosmic shear measurements}, volume = {992}, year = {2025}, }
• (2025). Turbulent magnetic fields and molecular cloud interactions in the supernova remnant g1.9+0.3. ApJ, 992(2), 204. (www)

  @article{ , abstract = {We present on results of a spatially resolved spectral analysis of G1.9+0.3, the youngest known supernova remnant in the Galaxy. The X-ray spectra are well described by synchrotron emission from a power-law electron distribution with an exponential cutoff. We found a cutoff energy 0 ∼ 1 keV in both the radio bright rim and the X-ray bright rims. In the loss-limited case, the cutoff energy depends on the shock velocity v sh and the Bohm factor η , following the relation {\epsilon }_{0}\propto {v}_{{\rm{sh}}}^{2}{\eta }^{-1} . Our analysis shows that η ranges from 2 to 4 in the radio rim and from 12 to 15 in the X-ray rims. This suggests that the magnetic field in the radio rim is more turbulent than in the X-ray rims. The presence of CO clouds along the radio rim likely contributes to this difference. Interaction between the shock and these clouds can slow the shock down and generate turbulent eddies. The resulting turbulence eddies can amplify the magnetic field. We propose that the strong radio emission from the radio rim is primarily due to this amplified magnetic field. In contrast, a CO cloud located in the southwest appears to lie in the foreground, as indicated by its low turbulence and the absence of shock deceleration.}, archive = {J_ApJ}, author = {Moeri Tao and Takaaki Tanaka and Hidetoshi Sano and Rami Z. E. Alsaberi and Jun Kataoka}, doi = {10.3847/1538-4357/ae0e14}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {204}, shortjournal = {The Astrophys. J.}, title = {Turbulent magnetic fields and molecular cloud interactions in the supernova remnant g1.9+0.3}, volume = {992}, year = {2025}, }
• (2025). First detection of ices in intermediate-mass young stellar objects beyond the milky way. ApJ, 992(2), 203. (www)

  @article{ , abstract = {Using NIRSpec on JWST, we studied a sample of 15 intermediate-mass (1.8–4.1 M ⊙ ) young stellar objects (YSOs) previously identified with MIRI photometry in the low-metallicity NGC 346 star-forming cluster in the Small Magellanic Cloud. All objects, observed in the 1.7–5.3 μ m range, show strong hydrogen recombination lines in the Paschen, Brackett, Pfund, and Humphreys series, confirming their very young ages. The spectra of 11 YSOs show prominent absorption bands from the three most important ice species (H 2 O, CO 2 , CO), marking the first detection of these ices in intermediate-mass YSOs beyond our Galaxy. In three YSOs, water ice appears to be in crystalline form. In some objects, we also detect 13 CO 2 and OCS ices—never before observed beyond the Milky Way (MW)—and methanol ice in at least one star. We compared the column densities of H 2 O, CO 2 , and CO ices with those measured in more and less massive protostars in the MW and Large Magellanic Cloud, finding that, in NGC 346, ice column densities reach values nearly an order of magnitude lower than in more massive objects (∼1 × 10 17 cm −2 for water and ∼1  × 10 16 cm −2 for CO 2 and CO). However, the relative proportions of the ice species abundances do not differ from those in massive MW YSOs. This suggests that metallicity may not significantly affect ice chemistry in protoplanetary disks and that, shielded by the protostellar envelope or deep in the midplane, circumstellar material is likely impervious to the radiation environment.}, archive = {J_ApJ}, author = {Guido De Marchi and Nolan Habel and Margaret Meixner and Katia Biazzo and Giovanna Giardino and Elena Sabbi and Ciaran Rogers and Jeroen Jaspers and Massimo Robberto and Peter Zeidler and Olivia C. Jones and Katja Fahrion and Alec S. Hirschauer and Charles D. Keyes and David R. Soderblom and Laura Lenkić and Omnarayani Nayak and Bernhard Brandl}, doi = {10.3847/1538-4357/ae03c2}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {203}, shortjournal = {The Astrophys. J.}, title = {First detection of ices in intermediate-mass young stellar objects beyond the milky way}, volume = {992}, year = {2025}, }
• (2025). Investigating the sulfur mystery in protoplanetary disks through chemical modeling. ApJ, 992(2), 202. (www)

  @article{ , abstract = {Sulfur is a critical element to life on Earth, and with detections of sulfur-bearing molecules in exoplanets and comets, questions arise as to how sulfur is incorporated into planets in the first place. In order to understand sulfur’s journey from molecular clouds to planets, we need to understand the molecular forms that sulfur takes in protoplanetary disks, where the rotational emission from sulfur-bearing molecules in the gas phase indicates a very low abundance. To address this question, we have updated the 2D time-dependent disk chemical modeling framework of J. K. J. Fogel et al. to incorporate several new sulfur species and hundreds of new sulfur reactions from the literature. Specifically, we investigate the main molecular forms that sulfur takes in a disk orbiting a solar-mass young T Tauri star. We explore the effects of different volatile (reactive) sulfur abundances, C/O ratios, initial sulfur molecular forms, and cosmic-ray ionization rates. We find that a high C/O ratio can explain both the prevalence of CS observed in disks and the lack of SO detections, consistent with previous results. Additionally, initial sulfur form greatly affects the ice abundances in the lower layers of the disk, which has implications for comet formation and future observations with JWST.}, archive = {J_ApJ}, author = {Becky J. Williams and L. Ilsedore Cleeves and Rachel E. Gross and Jackson Baker}, doi = {10.3847/1538-4357/ae0717}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {202}, shortjournal = {The Astrophys. J.}, title = {Investigating the sulfur mystery in protoplanetary disks through chemical modeling}, volume = {992}, year = {2025}, }
• (2025). Atmospheric gravity waves modulated by the magnetic field configuration. ApJ, 992(2), 201. (www)

  @article{ , abstract = {Atmospheric gravity waves (AGWs) are buoyancy-driven waves excited by turbulent convection and contribute to the dynamics and energy transport of the lower solar atmosphere. We present high-resolution, multiwavelength observations from the Interferometric Bidimensional Spectrometer (IBIS) and the Solar Dynamics Observatory to investigate AGW behavior across different viewing geometries and magnetic field configurations. Using Fourier spectral analysis to compute phase differences and coherence spectra, we detect the signature of propagating AGWs carrying energy upward at temporal and spatial scales consistent with theory, simulations, and prior observations. Although AGW behavior is modulated by the magnetic field configuration, particularly the field inclination, these effects are not highly discernible in our observed k h – ν phase difference diagrams. After filtering to isolate the AGW regime, we compute spatial coherence-weighted phase difference maps and examine binned coherence-weighted phase differences as functions of the field strength and inclination. Our results show that AGWs are efficiently suppressed and/or reflected in intermediate-to-strong, vertically oriented fields in the upper photosphere, while they propagate rather freely in quiet-Sun and transverse fields. These findings agree with a simulated vertical 100 G field using CO 5 BOLD. Simulated k h – ν phase differences derived from a 3D magnetohydrodynamic dispersion relation also qualitatively agree with our upper photospheric IBIS diagnostics and reinforce that the magnetic field configuration modulates the propagation of AGWs. This work demonstrates the potential of AGWs as magnetoseismology diagnostics for probing average magnetic field properties in the lower solar atmosphere.}, archive = {J_ApJ}, author = {Oana Vesa and Julio Morales and Jason Jackiewicz and Gangadharan Vigeesh and Kevin Reardon}, doi = {10.3847/1538-4357/ae0a55}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {201}, shortjournal = {The Astrophys. J.}, title = {Atmospheric gravity waves modulated by the magnetic field configuration}, volume = {992}, year = {2025}, }
• (2025). Diversity in planetary architectures from pebble accretion: Water delivery to the habitable zone with pebble snow. ApJ, 992(2), 200. (www)

  @article{ , abstract = {“Pebble snow” describes a planet formation mechanism where icy pebbles in the outer disk reach inner planet embryos as the water-ice line evolves inward. We model the effects pebble snow has on sculpting planetary system architectures by developing the “PPOLs model.” The model is capable of growing any number of protoplanet seed masses by pebble accretion simultaneously, and accounts for differences in rocky and icy pebble composition, the filtering of pebbles by other protoplanets, the pebble isolation mass, and a self-consistently evolving snow line. The growth and bulk composition are recorded across a grid of protoplanetary disks with stellar masses ranging from 0.125 to 2.0 M ⊙ (M to A stars) and disk masses ranging from 1% to 40% of the stellar mass. Three system architectures emerge following a low, medium, and high disk mass fraction that remains consistent across stellar mass. The low-mass architecture is the only one to yield short-period Mars- to Earth-mass cores with bulk water content spanning orders of magnitude and may be a prelude to observed “peas in pod” systems. The high-mass architecture produces proto–gas giant cores in the outer disk. The medium-mass architecture produces a bimodal peak in mass within a system, with the outer protoplanet mass at the snow line growing to an order of magnitude larger, resembling the solar system. Solar system–like architectures appear for a small range of initial disk masses around F and G stars, but are not a common feature around K and M stars.}, archive = {J_ApJ}, author = {Sean McCloat and Gijs D. Mulders and Sherry Fieber-Beyer}, doi = {10.3847/1538-4357/ae0301}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {200}, shortjournal = {The Astrophys. J.}, title = {Diversity in planetary architectures from pebble accretion: Water delivery to the habitable zone with pebble snow}, volume = {992}, year = {2025}, }
• (2025). Pinched magnetic fields in the high-mass protocluster w3 IRS5. ApJ, 992(2), 199. (www)

  @article{ , abstract = {We present polarization maps of dust emission at 340 GHz in the luminous high-mass protocluster W3 IRS5, observed with the Submillimeter Array. The projected magnetic fields appear fairly organized, with a pinched morphology in the northern part and a concave shape in the southern part. We fit the polarization maps with a two-component magnetic field model: an hourglass model centered at the continuum peak, SMM2, and an empirical sphere centered at the O-type star, IRS7. Using the Davis–Chandrasekhar–Fermi method, we calculate a projected field strength of B pos = 1.4 mG. Along with the Zeeman measurement, a total magnetic field strength of B tot = 1.6 mG is obtained. We find that gravitational energy is the most dominant, followed by magnetic energy and then turbulent energy. Small values of the virial parameter, α vir = 0.8, and the ratio of timescales, t ff / t cross = 0.6, suggest an ongoing collapse. We also show collimated molecular outflows in the CO (3−2) and SiO (8−7) transitions. The morphology of the magnetic fields and the surrounding H ii regions put forward a scenario for W3 IRS5. A gravitationally unstable dense core formed within a neutral gas ridge plowed by the expansions of W3 A and W3 B. The core began to contract, causing gravity to pull the magnetic field lines inward, which resulted in a pinched field morphology. The subsequent expansion of W3 F, ionized by IRS7, perturbed the magnetic field, creating the concave patterns. The dynamical interactions among protostars led to misalignment of their outflows.}, archive = {J_ApJ}, author = {Huei-Ru Vivien Chen and Qizhou Zhang and Tao-Chung Ching and H. Beuther and Kuo-Song Wang}, doi = {10.3847/1538-4357/adfbec}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {199}, shortjournal = {The Astrophys. J.}, title = {Pinched magnetic fields in the high-mass protocluster w3 IRS5}, volume = {992}, year = {2025}, }
• (2025). The cosmic shoreline revisited: A metric for atmospheric retention informed by hydrodynamic escape. ApJ, 992(2), 198. (www)

  @article{ , abstract = {The “cosmic shoreline,” a semi-empirical relation that separates airless worlds from worlds with atmospheres as proposed by K. J. Zahnle & D. C. Catling, is now guiding large-scale JWST surveys aimed at detecting rocky exoplanet atmospheres. We expand upon this framework by revisiting the shoreline using existing hydrodynamic escape models applied to Earth-like, Venus-like, and steam atmospheres for rocky exoplanets, and we estimate energy-limited escape rates for CH 4 atmospheres. We determine the critical instellation required for atmospheric retention by calculating time-integrated atmospheric mass loss. Our analysis introduces a new metric for target selection in the Rocky Worlds Director’s Discretionary Time and refines expectations for rocky planet atmosphere searches. Exploring initial volatile inventory ranging from 0.01% to 1% of planetary mass, we find that its variation prevents the definition of a unique clear-cut shoreline, though nonlinear escape physics can reduce this sensitivity to initial conditions. Additionally, uncertain distributions of high-energy stellar evolution and planet age further blur the critical instellations for atmospheric retention, yielding broad shorelines. Hydrodynamic escape models find atmospheric retention is markedly more favorable for higher-mass planets orbiting higher-mass stars, with carbon-rich atmospheres remaining plausible for 55 Cancri e despite its extreme instellation. We caution that our estimates are sensitive to processes with poorly understood dynamics, such as atomic line cooling. Finally, we illustrate how density measurements can be used to statistically test the existence of the cosmic shorelines, emphasizing the need for more precise mass and radius measurements.}, archive = {J_ApJ}, author = {Xuan Ji and Richard D. Chatterjee and Brandon Park Coy and Edwin Kite}, doi = {10.3847/1538-4357/adfe69}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {198}, shortjournal = {The Astrophys. J.}, title = {The cosmic shoreline revisited: A metric for atmospheric retention informed by hydrodynamic escape}, volume = {992}, year = {2025}, }
• (2025). Signals of bursts from the very early universe. ApJ, 992(2), 197. (www)

  @article{ , abstract = {We consider possible observable signals from explosive events in the very early Universe, dubbed “bursts.” These could be expected in connection with massive black hole or “baby Universe” formation. We anticipate that such major disruptions of spacetime would be associated with neutrino and perhaps other pulses. While these seem to be not detectable directly, we discuss how they could lead to potentially observable signals. We analyze how the pulses from very early times may “escape,” that is, propagate to the last scattering epoch at the time t cmb and later, or alternatively be absorbed earlier, i.e., “contained.” The possibly detectable signals include effects on small regions of the cosmic microwave background, a soft X-ray resulting from positron production, or a nonthermal addition to the relic neutrino background.}, archive = {J_ApJ}, author = {Leo Stodolsky and Joseph Silk}, doi = {10.3847/1538-4357/ae01a4}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {197}, shortjournal = {The Astrophys. J.}, title = {Signals of bursts from the very early universe}, volume = {992}, year = {2025}, }
• (2025). Detecting molecular hydrogen (H2) emission at cosmic dawn. ApJ, 992(2), 196. (www)

  @article{ , abstract = {We present a theoretical framework for interpreting far-ultraviolet (FUV) fluorescent emission from molecular hydrogen (H 2 ) in high-redshift galaxies, motivated by the unique capabilities of the James Webb Space Telescope (JWST) to probe the rest-frame FUV at cosmic dawn. Using the Meudon photodissociation region code, we model the H 2 fluorescence spectrum under extreme interstellar medium (ISM) conditions in terms of high pressure (10 11 K cm −3 ) and high radiation field (10 6 G 0 ), combined with low metallicity ( Z = 0.1 Z ⊙ ) and high cosmic ionization rate ( ζ = 10 −14 s −1 ), characteristic of early galaxies. As a case study, we apply this framework to stacked NIRSpec spectra from the JWST Advanced Deep Extragalactic Survey for galaxies at redshifts z ≥ 7. The stacked spectrum exhibits emission features consistent in profile and wavelength with the predicted H 2 fluorescence lines, including a blueshift suggestive of an outflow of molecular gas. Although individual features remain below robust detection thresholds, this demonstration illustrates the feasibility of using FUV fluorescence modeling to guide and interpret JWST spectroscopy of the molecular ISM at high redshift. Our framework provides a foundation for future searches for molecular hydrogen emission and the study of galactic feedback processes in the early Universe.}, archive = {J_ApJ}, author = {Madisen Johnson and Blakesley Burkhart and Francesco D’Eugenio and Sandro Tacchella and Roberto Maiolino and Shmuel Bialy and Jacques Le Bourlot and Evelyne Roueff and Franck Le Petit and Emeric Bron and Hervé Abgrall and Erica Nelson and Shyam Menon and Matthew E. Orr}, doi = {10.3847/1538-4357/ae032d}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {196}, shortjournal = {The Astrophys. J.}, title = {Detecting molecular hydrogen (H2) emission at cosmic dawn}, volume = {992}, year = {2025}, }
• (2025). Modeling long-wavelength amorphous dust emission based on the physically motivated soft-potential model. ApJ, 992(2), 195. (www)

  @article{ , abstract = {We propose a new amorphous dust emission model based on the soft-potential (SP) model, applicable in the long-wavelength range from the far-infrared to the microwave. The SP model is widely accepted in material physics to explain amorphous thermal properties and is an extension of the two-level systems (TLS) model, which has been applied in interstellar amorphous dust physics. In the SP model, by assuming that some atoms composing amorphous dust are trapped in a double-well potential (DWP) described by a quartic function, the electric interaction can be solved directly, allowing the absorption cross section of the amorphous dust to be calculated. We present numerical and analytical solutions for the absorption cross section of amorphous dust and compare these results, finding good agreement for the DWP with a sufficiently high potential barrier. Our findings show that the SP model can reproduce the observed spectrum of the Perseus molecular cloud with slightly better accuracy than the conventional TLS model. Additionally, the SP model can more effectively explain various long-wavelength dust emission features, such as the spectrum flattening in the submillimeter range and anomalous microwave emission, compared to the TLS model. Further comparison and verification with observational data and laboratory measurements are necessary to refine the model.}, archive = {J_ApJ}, author = {Masashi Nashimoto}, doi = {10.3847/1538-4357/ae03b4}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {195}, shortjournal = {The Astrophys. J.}, title = {Modeling long-wavelength amorphous dust emission based on the physically motivated soft-potential model}, volume = {992}, year = {2025}, }
• (2025). Does DESI DR2 challenge ΛCDM paradigm?. ApJ, 992(2), 194. (www)

  @article{ , abstract = {Although the debate about the systematic errors of DESI DR1 is still open, recent DESI DR2 is consistent with DESI DR1 and further strengthens the results of DESI DR1. In our analysis, both the LRG1 point at z eff = 0.510 and the LRG3+ELG1 point at z eff = 0.934 are in tension with the ΛCDM-anchored value of Ω m inferred from Planck and the Type Ia supernovae compilations Pantheon + , Union3, and DES-SN5YR. For luminous red galaxy 1 (LRG1) the tensions are 2.42 σ , 1.91 σ , 2.19 σ , and 2.99 σ , respectively; for LRG3+emission line galaxy 1 (ELG1) they are 2.60 σ , 2.24 σ , 2.51 σ , and 2.96 σ , respectively. From low to high redshift bins, DESI DR2 shows improved consistency relative to DESI DR1: the Ω m tension decreases from 2.20 σ to 1.84 σ . However, DESI DR2 alone does not provide decisive evidence against the ΛCDM model, and the apparent signal is largely driven by specific tracers, LRG1 and LRG2. In the ω 0 ω a CDM analysis, including all tracers yields a posterior mean with ω 0 > −1, which aligns with scenarios of dynamical dark energy as a potential explanation and suggests that the DESI DR2 challenges the ΛCDM paradigm. While removing LRG1 and/or LRG2 fully restores ΛCDM concordance (i.e., ω 0 → −1), we also find {\omega }_{0}^{\,\rm{(LRG1)}}\gt {\omega }_{0}^{\rm{(LRG2)}\,} , indicating LRG1 drives the apparent dynamical dark energy trend more strongly. Model selection using the natural log Bayes factor {\mathrm{ln}}{\rm{BF}}\equiv {\mathrm{ln}}({{ \mathcal Z }}_{{\rm{\Lambda }}{\rm{CDM}}}/{{ \mathcal Z }}_{{\omega }_{0}{\omega }_{a}{\rm{CDM}}}) shows weak evidence for ΛCDM when LRG1, LRG2, or both are removed, and it is inconclusive for the full sample; thus, the data do not require the extra ω a freedom, and the apparent ω 0 > −1 preference should be interpreted cautiously as a manifestation of the ω 0 – ω a degeneracy under limited per tracer information.}, archive = {J_ApJ}, author = {Himanshu Chaudhary and Salvatore Capozziello and Vipin Kumar Sharma and Ghulam Mustafa}, doi = {10.3847/1538-4357/ae0458}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {194}, shortjournal = {The Astrophys. J.}, title = {Does DESI DR2 challenge ΛCDM paradigm?}, volume = {992}, year = {2025}, }
• (2025). Driven collisionless reconnection of force-free flux tubes: From onset to coalescence. ApJ, 992(2), 193. (www)

  @article{ , abstract = {We investigate the onset of driven collisionless reconnection and plasmoid formation in a magnetically dominated pair plasma, using 2D particle-in-cell simulations. Two force-free flux tubes of radius R are initially pushed together with a prescribed velocity, forming a current sheet whose width shrinks until reconnection sets in. Even in our largest simulation with R ≈ 1600 plasma skin depths, the sheet thickness at reconnection onset is comparable to the skin depth. Plasmoid chains develop when the sheet length-to-width aspect ratio A ≳ 30. In the strongly magnetized limit, the onset of reconnection occurs in roughly 2–6 light-crossing times, depending on the imposed driving timescale, which controls the duration of the thinning phase. In the subsequent nonlinear merging phase, the evolution becomes effectively independent of the initially imposed velocity, leading to magnetic-energy dissipation consistent with a normalized reconnection rate ∼0.1. Our results have important implications for explosive release of magnetic energy in magnetospheres of astrophysical compact objects and their surroundings.}, archive = {J_ApJ}, author = {Camille Granier and Daniel Grošelj and Luca Comisso and Fabio Bacchini}, doi = {10.3847/1538-4357/ae0738}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {193}, shortjournal = {The Astrophys. J.}, title = {Driven collisionless reconnection of force-free flux tubes: From onset to coalescence}, volume = {992}, year = {2025}, }
• (2025). Scintillation properties of PSR b1133+16 measured with very long baseline interferometry. ApJ, 992(2), 192. (www)

  @article{ , abstract = {The scintillation of pulsars reveals the small-scale structure of the interstellar medium. A powerful technique for characterizing the scintillating structures (screens) combines analysis of scintillation arcs and very long baseline interferometry (VLBI). We present the results of a VLBI analysis of the scintillation arcs of PSR B1133+16 from simultaneous observations with Arecibo, Very Large Array, Jodrell Bank, Effelsberg, and Westerbork. Three arcs appear in the dataset, all of which appear consistent with being the result of very anisotropic scattering screens. We are able to measure their orientations on the sky, down to uncertainties of 5° for the two stronger screens, and measure distances of 140 ± 30, 180 ± 20, and 250 ± 30 pc, consistent with, but substantially more precise than what was inferred previously from annual modulation patterns in the scintillation. Compared with the differential dust extinction with distance in this direction, the two nearer screens appear associated with the wall of the Local Bubble.}, archive = {J_ApJ}, author = {Ashley M. Stock and Fardin Syed and Marten H. van Kerkwijk and Rebecca Lin and Franz Kirsten and Ue-Li Pen}, doi = {10.3847/1538-4357/ae0742}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {192}, shortjournal = {The Astrophys. J.}, title = {Scintillation properties of PSR b1133+16 measured with very long baseline interferometry}, volume = {992}, year = {2025}, }
• (2025). Stacking PANCAKEZ: Spectroscopic analysis with NIRSpec stacks in the epoch of reionization. weak interstellar medium absorption and implications for ionizing photon escape at z ∼ 7. ApJ, 992(2), 191. (www)

  @article{ , abstract = {We present a spectral stacking analysis of galaxies at z ≥ 6 observed with the James Webb Space Telescope (JWST). We curate a sample of 64 galaxies spanning redshifts z spec = 6.0–9.4, which have NIRSpec medium-resolution data. The stacks achieve sufficient signal-to-noise ratios to measure equivalent widths (EWs) and velocity centroids ( v cen ) of low-ionization species (LIS) absorption features, transmitted Ly α emission, and nebular emission lines. Overall, we find our sample has weaker LIS absorption lines (EW(LIS) ≈ 1 Å), smaller v cen,LIS ≈ –20 ± 50 km s −1 , and significantly suppressed Ly α (EW(Ly α ) ≈ 5 Å), compared to similar studies undertaken at lower redshift. The weaker LIS absorption may suggest a lower covering fraction of H I and larger escape fraction of ionizing photons from our sample. Additionally, the smaller blueshifted v cen,LIS indicates less prevalent or weaker outflows in z > 6 galaxies. Stacking our subsample of Ly α emitters (LAEs), we find high EW(H β ) ≈ 170 ± 4 Å and a detection of nebular C iv emission suggesting higher ξ ion in LAEs at z > 6. This work showcases the enormous potential for stacked JWST spectra revealing properties of galaxies and their diffuse interstellar medium in the epoch of reionization.}, archive = {J_ApJ}, author = {Kelsey S. Glazer and Tucker Jones and Yuguang Chen and Ryan L. Sanders and Maruša Bradač and Anthony J. Pahl and Alice E. Shapley and Richard S. Ellis and Michael W. Topping and Naveen A. Reddy}, doi = {10.3847/1538-4357/ae0194}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {191}, shortjournal = {The Astrophys. J.}, title = {Stacking PANCAKEZ: Spectroscopic analysis with NIRSpec stacks in the epoch of reionization. weak interstellar medium absorption and implications for ionizing photon escape at z ∼ 7}, volume = {992}, year = {2025}, }
• (2025). Natal kick by early-asymmetrical pairs of jets to the neutron star of supernova remnant s147. ApJ, 992(2), 190. (www)

  @article{ , abstract = {We analyze the bipolar morphology of the jet-shaped core-collapse supernova remnant (CCSNR) S147 and its neutron star (NS) kick velocity, and suggest that two pairs of unequal, opposite jets contributed to the NS kick velocity. This kick by early asymmetrical pairs (kick-BEAP) of jets mechanism operates within the framework of the jittering jets explosion mechanism (JJEM). We examine the prominent pair of large ears and, based on their flat structure rather than the more common conical structure of ears, conclude that two pairs of jets close in angle inflated the two opposite ears. We connect two opposite X-ray bright zones by an additional axis to create the full point-symmetric morphology of CCSNR S147. We propose that the two unequal jets that formed the X-ray bright zones imparted the first kick-BEAP, while the two pairs of jets that formed the ears imparted the second kick-BEAP. The two kick velocities are of about equal magnitude of ≃450 km s −1 , which implies very energetic jets. Such jets can excite gravitational waves that present detectors can detect from the Galaxy and the Magellanic Clouds. We use the morphology we identify to estimate the CCSNR age at 23,000 yr. Our results strengthen the JJEM.}, archive = {J_ApJ}, author = {Dmitry Shishkin and Ealeal Bear and Noam Soker}, doi = {10.3847/1538-4357/ae0332}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {190}, shortjournal = {The Astrophys. J.}, title = {Natal kick by early-asymmetrical pairs of jets to the neutron star of supernova remnant s147}, volume = {992}, year = {2025}, }
• (2025). Machine learning identification of gravitationally microlensed gamma-ray bursts. ApJ, 992(2), 189. (www)

  @article{ , abstract = {Gravitational microlensing of gamma-ray bursts (GRBs) provides a unique opportunity to probe compact dark matter and small-scale structures in the Universe. However, identifying such microlensed GRBs within large data sets is a significant challenge. In this study, we develop a machine learning (ML) approach to distinguish lensed GRBs from their nonlensed counterparts, using simulated light curves. A comprehensive data set is generated, comprising labeled light curves for both categories. Features are extracted using the Cesium package, capturing critical temporal properties of the light curves. Multiple ML models are trained on the extracted features, with Random Forest achieving the best performance, delivering an accuracy of 86% and an F 1 score of 0.86 (0.87) for the nonlensed (lensed) class. This approach successfully demonstrates the potential of ML for identifying gravitational lensing in GRBs, paving the way for future observational applications.}, archive = {J_ApJ}, author = {Mohammad H. Zhoolideh Haghighi and Zeinab Kalantari and Sohrab Rahvar and Alaa Ibrahim}, doi = {10.3847/1538-4357/ae03b1}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {189}, shortjournal = {The Astrophys. J.}, title = {Machine learning identification of gravitationally microlensed gamma-ray bursts}, volume = {992}, year = {2025}, }
• (2025). Monte carlo simulations of polarized radiative transfer in neutron star atmospheres. ApJ, 992(2), 188. (www)

  @article{ , abstract = {Soft X-ray emission from neutron stars affords powerful diagnostic tools for uncovering their surface and interior properties, as well as their geometric configurations. In the atmospheres of neutron stars, the presence of magnetic fields alters the photon-electron scattering cross sections, resulting in nontrivial angular dependence of intensity and polarization of the emergent signals. This paper presents recent developments of our Monte Carlo simulation, MAGTHOMSCATT, which tracks the complex electric field vector for each photon during its transport. Our analysis encompasses the anisotropy and polarization characteristics of X-ray emission for field strengths ranging from nonmagnetic to extremely magnetized regimes that are germane to magnetars. In the very low field domain, we reproduced the numerical solution to the radiative transfer equation for nonmagnetic Thomson scattering, and provided analytical fits for the angular dependence of the intensity and the polarization degree. These fits can be useful for studies of millisecond pulsars and magnetic white dwarfs. By implementing a refined injection protocol, we show that, in the magnetar regime, the simulated intensity and polarization pulse profiles of emission from extended surface regions becomes invariant with respect to the ratio of photon ( ω ) and electron cyclotron ( ω B ) frequencies once ω / ω B ≲ 0.01. This circumvents the need for simulations pertinent to really high magnetic field strengths, which are inherently slower. Our approach will be employed elsewhere to model observational data to constrain neutron star geometric parameters and properties of emitting hot spots on their surfaces.}, archive = {J_ApJ}, author = {Hoa Dinh Thi and Matthew G. Baring and Kun Hu and Alice K. Harding and Joseph A. Barchas}, doi = {10.3847/1538-4357/adf742}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {188}, shortjournal = {The Astrophys. J.}, title = {Monte carlo simulations of polarized radiative transfer in neutron star atmospheres}, volume = {992}, year = {2025}, }
• (2025). Rotational spectroscopy and tentative interstellar detection of 3-hydroxypropanal (HOCH2CH2CHO) in the g+0.693-0.027 molecular cloud. ApJ, 992(2), 187. (www)

  @article{ , abstract = {We synthesized the astrochemically relevant molecule 3-hydroxypropanal (HOCH 2 CH 2 CHO) and subsequently measured and analyzed its rotational spectrum in several frequency regions ranging from 130 to 485 GHz. We analyzed the ground vibrational state as well as the two perturbed lowest-lying vibrationally excited states. With the resulting rotational parameters, we searched for this molecule in the Sagittarius B2(N) and NGC 6334I hot cores, the IRAS 16293-2422B hot corino, and the G+0.693-0.027 and TMC-1 molecular clouds. Rotational emission of 3-hydroxypropanal was tentatively detected toward G+0.693-0.027, and a column density of (8.6 ±1.4) × 10 12 cm −2 was determined. However, this molecule was not detected in the other sources that were investigated. The chemical implications of this tentative discovery are analyzed, and several potential chemical formation pathways of this species are discussed.}, archive = {J_ApJ}, author = {Zachary T. P. Fried and Roman A. Motiyenko and Miguel Sanz-Novo and Lucie Kolesniková and Jean-Claude Guillemin and Laurent Margulès and Tereza Uhlíková and Arnaud Belloche and Jes K. Jørgensen and Martin S. Holdren and Ci Xue and Štěpán Urban and Izaskun Jiménez-Serra and Victor M. Rivilla and Brett A. McGuire}, doi = {10.3847/1538-4357/adfc62}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {187}, shortjournal = {The Astrophys. J.}, title = {Rotational spectroscopy and tentative interstellar detection of 3-hydroxypropanal (HOCH2CH2CHO) in the g+0.693-0.027 molecular cloud}, volume = {992}, year = {2025}, }
• (2025). A high-precision dynamical model of callisto: Incorporating rotation effects within multilayer internal structure models. ApJ, 992(2), 186. (www)

  @article{ , abstract = {China is planning to launch the “Tianwen-4” mission around the year 2030, with its aim being the exploration of Jupiter and its moon, Callisto. Within the realm of deep space exploration, the accuracy of ephemerides is of great importance. Current ephemerides employ a simplified rotation model for Callisto, which this study addresses by proposing a novel dynamical model. This model enhances the existing orbital dynamics by integrating Callisto’s rotational motions influenced by gravitational torques from the Sun, Jupiter, and other Galilean moons within an inertial frame, capturing the intricate coupling between Callisto’s orbital and rotational dynamics. The study establishes a full dynamical model by deriving analytical expressions for this coupling and developing an adjustment model for data fitting using precise orbit determination methods. Furthermore, the influence of tidal effects on Callisto’s motion is investigated, considering its multilayered internal structure. Results demonstrate that the difference between the newly established full model and the model in current ephemerides is on the order of tens of meters. When calculating the impact of different internal structures of Callisto on its orbit, the influence of three-layered and two-layered structures is on the order of meters, suggesting that the development of a high-precision dynamical model requires additional constraints on the internal structure of Callisto. This research provides a novel alternative for a new generation of precise numerical ephemerides for Callisto. Additionally, these findings provide a testing platform for the data from the “Tianwen-4” mission.}, archive = {J_ApJ}, author = {Kai Huang and Yongzhang Yang and Yuhao Chen and Yining Zhang and Yuqiang Li}, doi = {10.3847/1538-4357/adfe65}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {186}, shortjournal = {The Astrophys. J.}, title = {A high-precision dynamical model of callisto: Incorporating rotation effects within multilayer internal structure models}, volume = {992}, year = {2025}, }
• (2025). Long-term simultaneous 2.25/8.60 GHz monitoring of the newly discovered repeating FRB 20240114A. ApJ, 992(2), 185. (www)

  @article{ , abstract = {We report on the simultaneous monitoring of the repeating fast radio burst (FRB) 20240114A at 2.25 and 8.60 GHz, conducted 66 times between 2024 January 29 and 2025 February 15 with the Shanghai Tianma Radio Telescope. In about 180 hr of observation, we detected 155 bursts at 2.25 GHz above a fluence threshold of 0.72 Jy ms but none at 8.60 GHz above a fluence threshold of 0.27 Jy ms. FRB 20240114A exhibited frequency-dependent activity, as evidenced by the nondetections in 14.3 hr of observations at 2.25 GHz prior to 2024 February 24, despite its reported activity below 2 GHz. In contrast to its low-activity state reported below 1.4 GHz between 2024 June and December, FRB 20240114A exhibited high activity at 2.25 GHz in 2024 July with a mean burst rate of 1.7{2}_{-0.16}^{+0.18}\,{{\rm{hr}}}^{-1} , followed by a low-activity state. We also detected a short-term reactivation at 2.25 GHz around 2025 January 20, about 2 weeks after renewed activity was reported below 1.4 GHz by other telescopes. The median burst width at 2.25 GHz is 3 ms, which is narrower than that at lower frequencies. The waiting time distribution peaks at 1019 s, and bursts arrive on hourly timescales consistent with a Poisson process. The isotropic-equivalent energy of the bursts spans 10 37 –10 39 erg. The distribution of burst energy above the completeness threshold (7.5 × 10 37 erg) follows a power-law relation with an index of γ = −1.20 ± 0.03 ± 0.02. Finally, we find that FRB 20240114A is at least 2 orders of magnitude less active at 8.60 GHz than at 2.25 GHz, and we constrain the broadband spectra of the detected bursts.}, archive = {J_ApJ}, author = {Xiao-Wei Wang and Zhen Yan and Zhi-Qiang Shen and Ke-Jia Lee and Ya-Jun Wu and Rong-Bing Zhao and Jie Liu and Rui Wang and Kuo Liu and Yuan-Chuan Zou and Zhi-Peng Huang and Chu-Yuan Zhang and Fan Yang and Zhen-Long Liao and Yang-Yang Lin}, doi = {10.3847/1538-4357/adfece}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {185}, shortjournal = {The Astrophys. J.}, title = {Long-term simultaneous 2.25/8.60 GHz monitoring of the newly discovered repeating FRB 20240114A}, volume = {992}, year = {2025}, }
• (2025). New TeV-emitting BL lac candidates from the eROSITA X-ray survey. ApJ, 992(2), 184. (www)

  @article{ , abstract = {TeV-emitting BL Lac–type blazars represent the extreme end of the blazar population. They are characterized by relatively weak jets and radiatively inefficient accretion disks. Particles accelerated in these jets experience fewer radiative losses, allowing them to reach energies beyond the TeV scale and produce TeV gamma-ray emission. The study of TeV blazars is constrained by the limited number of known sources in this category. Currently, only 56 high-synchrotron-peaked BL Lacs have been detected at energies above 0.1 TeV. Searches for TeV emission from BL Lacs typically target sources with bright X-ray emission and a synchrotron peak at or above 1 keV. The recently released eRASS1 catalog by the eROSITA collaboration, which covers half of the sky, represents the deepest X-ray survey in the soft X-ray band to date. Utilizing the eROSITA survey, combined with infrared data from the Wide-field Infrared Survey Explorer and archival radio observations, we have identified 121 TeV-emitting blazar candidates. Our search introduces selection criteria based on the radio to infrared that remove quasar-like objects that have similar infrared spectra and X-ray fluxes as TeV-emitting BL Lacs. In our search, we find 23 objects that had not been detected in the ROSAT X-ray survey and 11 that have not been previously associated with blazars. The candidates resulting from our search are suitable for follow-up observations with currently operating imaging atmospheric Cherenkov telescopes, as well as future facilities like the CTAO Observatory.}, archive = {J_ApJ}, author = {Cassidy Metzger and Andrea Gokus and Manel Errando}, doi = {10.3847/1538-4357/adff87}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {184}, shortjournal = {The Astrophys. J.}, title = {New TeV-emitting BL lac candidates from the eROSITA X-ray survey}, volume = {992}, year = {2025}, }
• (2025). Electron acceleration in thinning nonreconnecting current sheets in a quasi-parallel shock. ApJ, 992(2), 183. (www)

  @article{ , abstract = {We study electron energization in turbulence-generated current sheets in the shock transition region by means of fully kinetic collisionless plasma simulations and theory. Using parameters in the Earth’s bow shock, we perform a two-dimensional particle-in-cell simulation of a quasi-parallel shock. In shock turbulence, many current sheets are produced, including those exhibiting magnetic reconnection and those that are not reconnecting. The electron temperature is enhanced in nonreconnecting current sheets as well as in reconnecting current sheets and magnetic islands. Performing electron trajectory tracing analysis, we find that energetic electrons are produced in nonreconnecting thinning current sheets. The motional electric field during the thinning process of a current sheet energizes both magnetized and unmagnetized electrons. We analytically show that the energization rate for unmagnetized electrons is slightly less than that of adiabatic energization for magnetized electrons, but unmagnetized electrons can be effectively trapped in magnetic field structures formed in thinning current sheets and continue to be energized. These nonreconnecting current sheets produce energetic electrons whose energies are comparable to the energetic electrons produced in magnetic islands, and they can reach the injection energy for diffusive shock acceleration, which is an acceleration mechanism for producing cosmic rays. The number of electrons that are energized in nonreconnecting current sheets is about a quarter of that in reconnection regions. The energization mechanism can be applicable to various space and astrophysical environments, including planetary bow shocks and supernova remnant shocks.}, archive = {J_ApJ}, author = {N. Bessho and L.-J. Chen and M. Hesse and J. Ng and L. B. Wilson and J. E. Stawarz}, doi = {10.3847/1538-4357/ae0327}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {183}, shortjournal = {The Astrophys. J.}, title = {Electron acceleration in thinning nonreconnecting current sheets in a quasi-parallel shock}, volume = {992}, year = {2025}, }
• (2025). The response of warm absorbers to the variations in the ionizing continuum in the active galaxy NGC 4051. ApJ, 992(2), 182. (www)

  @article{ , abstract = {We present a time-resolved X-ray spectral analysis of the warm absorbers in the Seyfert galaxy NGC 4051, which has an active galactic nucleus (AGN), using observations from the Neutron Star Interior Composition Explorer (NICER). Despite NICER’s moderate spectral resolution, its high-cadence monitoring allows us to probe the response of the ionized outflows, also known as warm absorbers, on timescales of ∼5500 s. We detect two distinct components of ionized absorbers in this source. The variability in the ionization parameter of the low-ionization warm absorber component, which tracks changes in the ionizing flux with no measurable time lag. This rapid response implies photoionization equilibrium and places a lower limit on the electron density of ≳9 × 10 6 cm −3 based on the most abundant ionic species, O VII . The absorber is located within ∼0.02 pc of the central source, consistent with an origin in the inner regions of the active nucleus. In contrast, the high-ionization absorber remains consistently under-ionized relative to equilibrium predictions. This suggests that it may be the collisional plasma, which was also detected in this source in the previous studies. These results demonstrate that time-resolved spectroscopy, even with moderate-resolution instruments, can provide valuable constraints on the density and location of warm absorbers in AGN. As a potential candidate source of AGN feedback, the study of these ionized outflows is crucial in understanding AGN–host galaxy interactions.}, archive = {J_ApJ}, author = {Dev R. Sadaula and Timothy R. Kallman and Sibasish Laha}, doi = {10.3847/1538-4357/ae032f}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {182}, shortjournal = {The Astrophys. J.}, title = {The response of warm absorbers to the variations in the ionizing continuum in the active galaxy NGC 4051}, volume = {992}, year = {2025}, }
• (2025). Searching for continuous gravitational waves in the parkes pulsar timing array data release 3. ApJ, 992(2), 181. (www)

  @article{ , abstract = {We present results from an all-sky search for continuous gravitational waves from individual supermassive binary black holes using the third data release of the Parkes Pulsar Timing Array (PPTA). Even though we recover a common-spectrum stochastic process, potentially induced by a nanohertz gravitational-wave background, we find no evidence of continuous waves. Therefore, we place upper limits on the gravitational-wave strain amplitude: in the most sensitive frequency range around 10 nHz, we obtain a sky-averaged 95% credibility upper limit of ≈ 7 × 10 −15 . Our search is sensitive to supermassive binary black holes with a chirp mass of ≥10 9 M ⊙ up to a luminosity distance of 50 Mpc for our least sensitive sky direction and 200 Mpc for the most sensitive direction. This work provides at least 4 times better sensitivity in the 1–200 nHz frequency band than our last search based on the PPTA’s first data release. We expect that PPTA will continue to play a key role in detecting continuous gravitational waves in the exciting era of nanohertz gravitational-wave astronomy.}, archive = {J_ApJ}, author = {Shi-Yi Zhao and Zu-Cheng Chen and Jacob Cardinal Tremblay and Boris Goncharov and Xing-Jiang Zhu and N. D. Ramesh Bhat and Małgorzata Curyło and Shi Dai and Valentina Di Marco and Hao Ding and George Hobbs and Agastya Kapur and Wenhua Ling and Tao Liu and Rami Mandow and Saurav Mishra and Daniel J. Reardon and Christopher J Russell and Ryan M. Shannon and Shuangqiang Wang and Lei Zhang and Andrew Zic}, doi = {10.3847/1538-4357/ae0719}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {181}, shortjournal = {The Astrophys. J.}, title = {Searching for continuous gravitational waves in the parkes pulsar timing array data release 3}, volume = {992}, year = {2025}, }
• (2025). Estimation of effective viscosity to quantify collisional behavior in collisionless plasma. ApJ, 992(2), 180. (www)

  @article{ , abstract = {While dissipation in collisional plasma is defined in terms of viscosity and resistivity, the exact functional form of dissipation, i.e., the so-called dissipation function in nearly collisionless plasma, is unknown. Nevertheless, previous studies have suggested that there exists viscous-like energy conversion in collisionless plasma with scaling characteristics analogous to collisional plasma, and in particular that the average dissipation is proportional to the square of the rate of strain as in hydrodynamics. In this study, using 2.5D kinetic particle-in-cell (PIC) simulation of collisionless plasma turbulence, we provide an estimate of effective viscosity at each scale, obtained via a scale-filtering approach. We then compare the turbulent dynamics of the PIC simulation with that from MHD and two-fluid simulations in which the viscosity is equal to the effective viscosity estimate obtained from the PIC simulation. We find that the global behavior in these MHD and two-fluid simulations has a striking similarity to that in their kinetic/PIC counterpart. In addition, we explore the scale dependence of the effective viscosity and discuss implications of this approach for space plasmas.}, archive = {J_ApJ}, author = {Subash Adhikari and Carlos A. González and Yan Yang and Sean Oughton and Francesco Pecora and Riddhi Bandyopadhyay and William H. Matthaeus}, doi = {10.3847/1538-4357/ae08b4}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {180}, shortjournal = {The Astrophys. J.}, title = {Estimation of effective viscosity to quantify collisional behavior in collisionless plasma}, volume = {992}, year = {2025}, }
• (2025). Evolution of low surface brightness ultrathin galaxies: The role of dark matter halo and bar formation on disk thickness. ApJ, 992(2), 179. (www)

  @article{ , abstract = {We investigate how stellar disks sustain their ultrathin structure throughout their evolution. We follow the evolution of ultrathin stellar disks with varying dark matter (DM) halo concentration ( c ) using collisionless N -body simulations with AREPO . We test models embedded in steep ( c = 12), shallow ( c = 2), and intermediate ( c = 6) DM concentrations. Our models match the observed structural properties of the stellar disk in the low surface brightness (LSB) ultrathin galaxy FGC 2366, specifically its surface brightness, disk scalelength, and vertical thinness ( h z / R D = 0.1), while excluding gas, allowing us to isolate the effects of DM. The internal disk heating mechanism driven by bars is suppressed in the LSB ultrathin stellar disks regardless of the DM concentration. The ratio of disk thickness ( h z ) to scalelength ( R D ) remains constant at ≤0.1 throughout their evolution. To clearly establish that the LSB nature of stellar disks is the key to preventing disk thickening, we construct the initial conditions by increasing the stellar mass fraction from f s ∼ 0.01 to 0.02 and 0.04, respectively, while keeping the total mass equal to 10 11 M ⊙ and h z / R D ≤ 0.1 unchanged. We find that models with a higher stellar mass fraction embedded in a shallow DM potential ( c = 2) form bars and undergo significant disk thickening ( h z / R D ≫ 0.1) concurrent with the bar growth. We conclude that if the LSB disks are thin to begin with, they remain so throughout their evolution in isolation, regardless of the concentration of the DM halo.}, archive = {J_ApJ}, author = {K. Aditya and Arunima Banerjee}, doi = {10.3847/1538-4357/ae0991}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {179}, shortjournal = {The Astrophys. J.}, title = {Evolution of low surface brightness ultrathin galaxies: The role of dark matter halo and bar formation on disk thickness}, volume = {992}, year = {2025}, }
• (2025). Low-latitude sunspot group tilt angles in 15–24 activity cycles. ApJ, 992(2), 178. (www)

  @article{ , abstract = {An analysis of the tilt angles of the active regions in 15–24 activity cycles was performed. We used data from measurements of magnetic fields in the sunspot umbra in the period 1918–2019 at the Mount Wilson Observatory, as well as the tilt angles of active regions in “white” light at the Kodaikanal and Mount Wilson observatories in activity cycles 15–21. The mean tilt angles of active regions \overline{\gamma } and the slope μ from latitude θ in the activity cycles are considered. Low-latitude bipoles are the most important in predicting the strength of solar cycles. In this work, we selected the cutoff latitude θ cut at which the highest correlation is observed with the strength of the next activity cycle for active regions with latitude θ < θ cut . It was found that for magnetic field measurement data, the highest correlation of the parameters \overline{\gamma } and μ with the strength of the next solar activity cycle is characteristic of bipoles in the equatorial zone with θ < θ cut ≈ 14 \mathop{.}\limits^{\unicode{x000b0}} 2. For “white” light observation data, θ cut ≈ 8 \mathop{.}\limits^{\unicode{x000b0}} 5 for Mount Wilson Observatory and θ cut ≈ 9 \mathop{.}\limits^{\unicode{x000b0}} 4 for Kodaikanal Observatory.}, archive = {J_ApJ}, author = {Andrey G. Tlatov}, doi = {10.3847/1538-4357/ae09a7}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {178}, shortjournal = {The Astrophys. J.}, title = {Low-latitude sunspot group tilt angles in 15–24 activity cycles}, volume = {992}, year = {2025}, }
• (2025). Analysis of short-term solar activity variability and estimating the timings of the next enhanced bursts. ApJ, 992(2), 177. (www)

  @article{ , abstract = {We present a novel hybrid forecasting strategy combining numerical, statistical, and machine learning–based forecasting to detect the occurrence of the next enhanced solar activity bursts. These enhanced bursts are called “space weather seasons,” which occur on intermediate timescales (6–18 months). Monthly smoothed sunspot number (SSN) data from 1878 to 2025 are analyzed using Gaussian fitting techniques to identify burst events and their properties such as amplitude and duration. The SSN data are divided into training, test, and forecast, which shows hindcast and forecast. Each hemisphere is modeled via a seasonal autoregressive integrated moving average approach, refined with an asymmetric Gaussian override to capture rapid burst rise and gradual decay, and burst amplitudes and duration are predicted using a random forest regression model. This hybrid approach successfully hindcasts burst timing in between 2024 November and 2025 May, with a peak SSN of ∼70 around 2025 March for the Northern Hemisphere. The next burst in the Northern Hemisphere is forecast to be in 2025 December with a slightly lower SSN of 60. By contrast, the Southern Hemisphere shows relatively complicated behavior, where the bursts show multiple amplitudes starting approximately in 2024 October and ending in 2025 October. The main burst shows an amplitude of 130 SSN. The next burst in the Southern Hemisphere is forecast to occur approximately in 2025 December. Combining SSN properties in both hemispheres, we find that the total SSN is mainly influenced by a stronger cycle in the Southern Hemisphere.}, archive = {J_ApJ}, author = {Juie Shetye and Mausumi Dikpati}, doi = {10.3847/1538-4357/ae0470}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {177}, shortjournal = {The Astrophys. J.}, title = {Analysis of short-term solar activity variability and estimating the timings of the next enhanced bursts}, volume = {992}, year = {2025}, }
• (2025). Central massive black holes are not ubiquitous in local low-mass galaxies. ApJ, 992(2), 176. (www)

  @article{ , abstract = {The black hole occupation fraction ( f occ ) defines the fraction of galaxies that harbor central massive black holes (MBHs), irrespective of their accretion activity level. While it is widely accepted that f occ is nearly 100% in local massive galaxies with stellar masses M ⋆ ≳ 10 10 M ⊙ , it is not yet clear whether MBHs are ubiquitous in less-massive galaxies. In this work, we present new constraints on f occ based on over 20 yr of Chandra imaging data for 1606 galaxies within 50 Mpc. We employ a Bayesian model to simultaneously constrain f occ and the specific accretion-rate distribution function, p ( λ ), where the specific accretion rate is defined as λ = L X / M ⋆ , where L X is the MBH accretion luminosity in the 2–10 keV range. Notably, we find that p ( λ ) peaks around 1{0}^{28}\,{\rm{erg}}\,{{\rm{s}}}^{-1}\,{M}_{\odot }^{-1} ; above this value, p ( λ ) decreases with increasing λ , following a power law that smoothly connects with the probability distribution of bona fide active galactic nuclei. We also find that the occupation fraction decreases dramatically with decreasing M ⋆ : in high-mass galaxies ( M ⋆ ≈ 10 11−12 M ⊙ ), the occupation fraction is >93% (a 2 σ lower limit), and then declines to 66{ \% }_{-7 \% }^{+8 \% } (1 σ errors) between M ⋆ ≈ 10 9−10 M ⊙ , and to 33{ \% }_{-9 \% }^{+13 \% } in the dwarf galaxy regime between M ⋆ ≈ 10 8−9 M ⊙ . Our results have significant implications for the normalization of the MBH mass function over the mass range most relevant for tidal disruption events, extreme mass ratio inspirals, and MBH merger rates that upcoming facilities are poised to explore.}, archive = {J_ApJ}, author = {Fan Zou and Elena Gallo and Anil C. Seth and Edmund Hodges-Kluck and David Ohlson and Tommaso Treu and Vivienne F. Baldassare and W. N. Brandt and Jenny E. Greene and Piero Madau and Dieu D. Nguyen and Richard M. Plotkin and Amy E. Reines and Alberto Sesana and Jong-Hak Woo and Jianfeng Wu}, doi = {10.3847/1538-4357/ae06a1}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {176}, shortjournal = {The Astrophys. J.}, title = {Central massive black holes are not ubiquitous in local low-mass galaxies}, volume = {992}, year = {2025}, }
• (2025). Vibrational spectroscopy of ${{\rm{C}}}_{60}^{+}$ and ${{\rm{C}}}_{70}^{+}$ in the mid-infrared: A comparison with astronomical observations. ApJ, 992(2), 175. (www)

  @article{ , abstract = {In recent years, astronomical observations, in combination with laboratory spectra and theoretical modeling, have confirmed the presence of C 60 , {{\rm{C}}}_{60}^{+} and C 70 across a broad range of astrophysical objects. Despite expectations that {{\rm{C}}}_{70}^{+} should also be present in space, its detection is difficult to confirm due to both the lack of laboratory gas-phase IR spectra and challenges in calculating its vibrational spectrum. This study presents gas-phase IR spectroscopy of {{\rm{C}}}_{70}^{+} between 6 and 9 μ m (1100−1625 cm −1 ) under astrochemically relevant conditions. The large discrepancies between the experimental and theoretical spectra of {{\rm{C}}}_{70}^{+} highlight the challenges of calculating the complex vibrational spectrum of this ion and emphasize the need for laboratory data for comparison to astronomical observations. Additionally, new spectroscopic data of {{\rm{C}}}_{60}^{+} are provided, showing the mid-IR spectra of both fullerene cations are dominated by features around 7 μ m, where strong emission from planetary nebulae is observed. These results are compared with emission from SMP LMC 56 and Tc 1, providing a foundation to search for {{\rm{C}}}_{70}^{+} in space.}, archive = {J_ApJ}, author = {Thomas E. Douglas-Walker and Olivia O’Neill and Ewen K. Campbell}, doi = {10.3847/1538-4357/adf6de}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {175}, shortjournal = {The Astrophys. J.}, title = {Vibrational spectroscopy of ${{\rm{C}}}_{60}^{+}$ and ${{\rm{C}}}_{70}^{+}$ in the mid-infrared: A comparison with astronomical observations}, volume = {992}, year = {2025}, }
• (2025). Starspot temperature of CoRoT-2 from multiwavelength observations with SPARC4. ApJ, 992(2), 174. (www)

  @article{ , abstract = {Measuring starspot temperatures is crucial for understanding stellar magnetic activity as it affects stellar brightness variations, influences exoplanet transit measurements, and provides constraints on the physical conditions and energy transport in active regions, offering insights into stellar dynamos. Our goal is to determine the temperature of starspots on the active star CoRoT-2 to enhance our understanding of magnetic activity in young, solar-like stars. Multiwavelength observations were conducted using the Simultaneous Polarimeter and Rapid Camera in Four bands instrument on the 1.6 m telescope at Pico dos Dias Observatory (Brazil), capturing simultaneous transit data in four photometric bands ( g , r , i , and z ). The ECLIPSE model, combined with Markov Chain Monte Carlo fitting, was used to model spot characteristics during the planetary transit of CoRoT-2 b. The spot intensities were analyzed considering three different methods: the assumption of blackbody emission, the PHOENIX atmospheric model, and multiwavelength fitting assuming the same spot parameters for all wavelengths. Two starspots were detected in the residuals of the light curve, yielding temperature estimates of 5040–5280 K based on the three different methods. These values align more closely with the temperatures of solar penumbrae than with typical umbral temperatures, suggesting relatively moderate magnetic activity. The radius of the spots ranged from 0.34 to 0.61 the planetary radius, or equivalently (38–69) × 10 6 m, much larger than sunspots. This study provides a method to estimate spot temperatures on active stars using multiband photometry, with results indicating penumbral-like temperatures on CoRoT-2. The methodology enhances precision in starspot temperature estimation, beneficial for studies of stellar activity and exoplanet characterization.}, archive = {J_ApJ}, author = {Adriana Valio and Eder Martioli and Andre O. Kovacs and Viktor Y. D. Sumida and Leandro de Almeida and Diego Lorenzo-Oliveira and Francisco Jablonski and Claudia V. Rodrigues}, doi = {10.3847/1538-4357/adf8e2}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {174}, shortjournal = {The Astrophys. J.}, title = {Starspot temperature of CoRoT-2 from multiwavelength observations with SPARC4}, volume = {992}, year = {2025}, }
• (2025). Multifidelity emulator for large-scale 21 cm lightcone images: A few-shot transfer learning approach with generative adversarial network. ApJ, 992(2), 173. (www)

  @article{ , abstract = {Emulators using machine learning techniques have emerged to efficiently generate mock data matching the large survey volume for upcoming experiments, as an alternative approach to large-scale numerical simulations. However, high-fidelity emulators have become computationally expensive as the simulation volume grows to hundreds of megaparsecs. Here, we present a multifidelity emulation of large-scale 21 cm lightcone images from the epoch of reionization, which is realized by applying the few-shot transfer learning to training generative adversarial networks (GAN) from small-scale to large-scale simulations. Specifically, a GAN emulator is first trained with a huge number of small-scale simulations, and then transfer-learned with only a limited number of large-scale simulations, to emulate large-scale 21 cm lightcone images. We test the precision of our transfer-learned GAN emulator in terms of representative statistics including global 21 cm brightness temperature history, 2D power spectrum, and scattering transform coefficients. We demonstrate that the lightcone images generated by the transfer-learned GAN emulator can reach the percentage level precision in most cases on small scales, and the error on large scales only increases mildly to the level of a few tens of percent. Nevertheless, our multifidelity emulation technique saves a significant portion of computational resources that are mostly consumed for generating training samples for GAN. On estimate, the computational resource by training GAN completely with large-scale simulations would be 1 to 2 orders of magnitude larger than using our multifidelity technique. This implies that our technique allows for emulating high-fidelity, traditionally computationally prohibitive, images in an economic manner.}, archive = {J_ApJ}, author = {Kangning Diao and Yi Mao}, doi = {10.3847/1538-4357/ae0325}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {173}, shortjournal = {The Astrophys. J.}, title = {Multifidelity emulator for large-scale 21 cm lightcone images: A few-shot transfer learning approach with generative adversarial network}, volume = {992}, year = {2025}, }
• (2025). Evaluating the limits of rotation period recovery through gyrochronology criteria. ApJ, 992(2), 172. (www)

  @article{ , abstract = {Contamination from nearby sources often compromises stellar rotation periods derived from photometric light curves, particularly in data with large pixel scales such as The Transiting Exoplanet Survey Satellite (TESS). This problem is compounded when both the target and contaminant are intrinsically variable, a scenario that challenges deblending algorithms, which often assume constant contaminants. We assess the reliability of rotation period detections using wide binary systems, whose components share a common age and rotational history. By applying gyrochronology constraints, we identify period combinations that yield consistent ages between components, helping to isolate true rotation signals. Simulating blends with degraded Kepler data, our method recovers correct rotation periods with an 88% success rate for periods <12 days, where TESS detections are most reliable. Applying this framework to nearly 300 wide binaries observed by TESS, we find that, despite significant contamination, a subset of pairs shows consistent gyrochronological ages. We establish a practical detection threshold for TESS blended observations, finding that periods shorter than ∼8 days are reliably recovered, while those longer than ∼10 days become significantly more challenging and often remain inconclusive. As expected, rotation periods are more often recovered when the highest-amplitude periodogram peak is linked to the brighter star and the second to the dimmer star. However, many cases deviate from this pattern, indicating it cannot always be assumed. Our results highlight the limitations of standard deblending methods and demonstrate that astrophysical constraints, such as gyrochronology, provide a valuable tool for extracting reliable rotation periods from complex photometric blends.}, archive = {J_ApJ}, author = {Mariel Lares-Martiz and Terry D. Oswalt and Derek L. Buzasi and Kylie R. Boyer and Luca Guida and Ryan J. Reynolds}, doi = {10.3847/1538-4357/ae03a7}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {172}, shortjournal = {The Astrophys. J.}, title = {Evaluating the limits of rotation period recovery through gyrochronology criteria}, volume = {992}, year = {2025}, }
• (2025). Unions with UNIONS: Using Galaxy–Galaxy lensing to probe galaxy mergers. ApJ, 992(2), 171. (www)

  @article{ , abstract = {We use galaxy–galaxy lensing to investigate how the dark matter (DM) haloes and stellar content of galaxies with 0.012 ≤ z ≤ 0.32 and 10\,\leqslant \,{\mathrm{log}}\,_{10}({M}_{\star }/{M}_{\odot })\,\leqslant \,12 change as a result of the merger process. To this end, we construct two samples of galaxies obtained from the Ultraviolet Near Infrared Optical Northern Survey, comprising 1623 postmergers and ∼30,000 nonmerging controls, that live in low-density environments to use as our lenses. These samples are weighted to share the same distributions of stellar mass, redshift, and geometric mean distance to a galaxy’s three nearest neighbors to ensure differences in the lensing signal are due to the merger process itself. We do not detect a statistically significant difference in the excess surface density profile of postmergers and nonmerging controls with current data. Fitting haloes composed of a pointlike stellar mass component and an extended DM structure described by a Navarro–Frenk–White profile to the lensing measurements yields, for both samples, halo masses of M halo ∼ 4 × 10 12 M ⊙ and a moderately negative correlation between M halo and concentration c . This allows us to rule out, at the 95% confidence level, merger-induced starbursts in which more than 60% of the stellar mass is formed in the burst. The application of our methods to upcoming surveys that are able to provide samples ∼10× larger than our current catalog is expected to detect the weak-lensing signatures of mergers and further constrain their properties.}, archive = {J_ApJ}, author = {Isaac Cheng and Jack Elvin-Poole and Michael J. Hudson and Ruxin Barré and Sara L. Ellison and Robert W. Bickley and Thomas J. L. de Boer and Sébastien Fabbro and Leonardo Ferreira and Sacha Guerrini and Fabian Hervas Peters and Hendrik Hildebrandt and Martin Kilbinger and Alan W. McConnachie and Ludovic van Waerbeke and Anna Wittje}, doi = {10.3847/1538-4357/ae03b8}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {171}, shortjournal = {The Astrophys. J.}, title = {Unions with UNIONS: Using Galaxy–Galaxy lensing to probe galaxy mergers}, volume = {992}, year = {2025}, }
• (2025). Fermi detection of γ-rays from the radio-quiet seyfert galaxy NGC 3281. ApJ, 992(2), 170. (www)

  @article{ , abstract = {We report the detection of significant γ -ray emission with the Fermi Large Area Telescope from the radio-quiet Seyfert 2 galaxy NGC 3281, with a luminosity of 5.9 (±1.7) × 10 41 erg s −1 at a significance of 6.22 σ (TS = 42.81). The power-law photon index is 2.61 (±0.24), indicative of a soft spectrum. The star formation activity in NGC 3281 is insufficient to explain its γ -ray luminosity based on the empirical relation between the infrared and γ -ray luminosities observed in other sources. The multiwavelength spectrum can be explained as due to inverse Compton scattering by relativistic electrons in the corona or the jet of seed photons from the corona, disk, and torus. The source is Compton thick, and attenuation of GeV photons due to pair production in the corona is nonnegligible (with an optical depth of about 10). The intrinsic γ -ray luminosity is inferred to be 3.4 × 10 42 and 2.2 × 10 41 erg s −1 for the corona and jet model, respectively. The observed γ -ray and radio luminosities are roughly consistent with the known correlation between the two quantities, among the lowest-luminosity regime. The jet origin is valid only if the radio emission is dominated by the jet.}, archive = {J_ApJ}, author = {Jun-Rong Liu and Hua Feng and Jian-Min Wang}, doi = {10.3847/1538-4357/ae07cf}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {170}, shortjournal = {The Astrophys. J.}, title = {Fermi detection of γ-rays from the radio-quiet seyfert galaxy NGC 3281}, volume = {992}, year = {2025}, }
• (2025). On the formation of star-forming galaxies having anomalously low-metallicity regions: The role of galaxy interaction and circumgalactic Medium/Intergalactic medium accretion. ApJ, 992(2), 169. (www)

  @article{ , abstract = {Gas accretion from both the circumgalactic medium (CGM)/intergalactic medium (IGM) and interacting companion galaxy can dilute the gas phase metallicity of a galaxy. However, their relative contribution to the chemical evolution of galaxies remains to be quantified. To this end, in this work we study a sample of 510 star-forming galaxies (SFGs) having anomalously low-metallicity (ALM) regions selected from the MaNGA data available in the Data Release 17 from the Sloan Digital Sky Survey. ALM regions are defined as those having gas-phase metallicities that are at least ∼2 σ lower than the empirical relation between stellar mass surface density (Σ * ) and gas phase metallicity, i.e., the Σ * – Z relation. We find that ALM galaxies have higher star formation rates and H i gas fractions than normal SFGs at fixed M * . Also, ∼25% of the ALM galaxies exhibit tidal features, while the tidal fraction is only ∼12% for normal SFGs, indicating that galaxy interaction is an important factor responsible for the ALM phenomenon. To explore the origin of nontidal ALM galaxies, we compare their morphologies and environments with those of mass-matched normal SFGs. We find that nontidal ALM galaxies tend to have more disk-dominated morphologies and reside in less-dense environment. These findings suggest that cold gas accretion from the CGM/IGM is the primary cause for the ALM phenomenon, while galaxy interaction plays a minor but nonnegligible role.}, archive = {J_ApJ}, author = {Yibo Cao and Zhizheng Pan}, doi = {10.3847/1538-4357/ae0a10}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {169}, shortjournal = {The Astrophys. J.}, title = {On the formation of star-forming galaxies having anomalously low-metallicity regions: The role of galaxy interaction and circumgalactic Medium/Intergalactic medium accretion}, volume = {992}, year = {2025}, }
• (2025). Evolution of large-scale structures in the energetic neutral atom sky maps in energy and solar activity. ApJ, 992(2), 168. (www)

  @article{ , abstract = {The heliospheric energetic neutral atoms (ENAs) are products of charge exchange between solar wind and pick-up ions and interstellar neutral atoms. They are created in different regions of the heliosphere and its boundary region with the interstellar medium, constituting different ENA populations, and they carry information about their parent populations and production processes. Thus, ENAs enable mapping of the global structure of the heliosphere and the processes within and at its edge. Three instruments have provided sky maps of the heliospheric ENAs from 200 eV up to 44 keV over the solar activity cycle. The IBEX-Lo and IBEX-Hi instruments on board the Interstellar Boundary Explorer (IBEX) have provided ENA sky maps from 200 eV to 4.3 keV (central energy) from 2009 throughout Solar Cycle 24. The Ion and Neutral Camera (INCA) on board the Cassini–Huygens mission provided sky maps of the ENAs from 8–44 keV (central energy) on the spacecraft route to and in orbit around Saturn through Solar Cycles 23 and 24. We compare large-scale structures of ENA enhancements present across the sky maps in a wide energy range based on IBEX-Lo, IBEX-Hi, and INCA. They include Ribbon, heliotail lobes, and upwind ENA enhancement. We report on similarities and differences observed, including the evolution of the Ribbon from low to higher energies, and the presence of confined north and south heliotail lobes up to 44 keV.}, archive = {J_ApJ}, author = {Justyna M. Sokół and Jonathan Gasser and Merav Opher and Marc Kornbleuth and Kostas Dialynas and André Galli and Maher A. Dayeh and Stephen A. Fuselier and Daniel B. Reisenfeld and Herbert O. Funsten}, doi = {10.3847/1538-4357/adfa24}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {168}, shortjournal = {The Astrophys. J.}, title = {Evolution of large-scale structures in the energetic neutral atom sky maps in energy and solar activity}, volume = {992}, year = {2025}, }
• (2025). Transiting planetary debris near the roche limit of a white dwarf on a 4.97 hr orbit—and its vanishing. ApJ, 992(2), 167. (www)

  @article{ , abstract = {We present the discovery of deep, irregular, periodic transits toward the white dwarf ZTF J1944+4557 using follow-up time-series photometry and spectroscopy from Palomar, Keck, McDonald, Perkins, and Lowell observatories. We find a predominant period of 4.9704 hr, consistent with an orbit near the Roche limit of the white dwarf, with individual dips over 30% deep and lasting between 15 and 40 minutes. Similar to the first known white dwarf with transiting debris, WD 1145+017, the transit events are well-defined with prominent out-of-transit phases where the white dwarf appears unobscured. Spectroscopy concurrent with transit photometry reveals that the average Ca K equivalent width remains constant in and out of transit. The broadening observed in several absorption features cannot be reproduced by synthetic photospheric models, suggesting the presence of circumstellar gas. Simultaneous g + r - and g + i -band light curves from the CHIMERA instrument reveal no color dependence to the transit depths, requiring transiting dust grains to have sizes s ≳  0.2 μ m. The transit morphologies appear to be constantly changing at a rate faster than the orbital period. Overall transit activity varies in the system, with transit features completely disappearing during the seven months between our 2023 and 2024 observing seasons and then reappearing in 2025 March, still repeating at 4.9704 hr. Our observations of the complete cessation and resumption of transit activity provide a novel laboratory for constraining the evolution of disrupted debris and processes like disk exhaustion and replenishment timescales at white dwarfs.}, archive = {J_ApJ}, author = {Joseph A. Guidry and Zachary P. Vanderbosch and J. J. Hermes and Dimitri Veras and Mark A. Hollands and Soumyadeep Bhattacharjee and Ilaria Caiazzo and Kareem El-Badry and Malia L. Kao and Lou Baya Ould Rouis and Antonio C. Rodriguez and Jan van Roestel}, doi = {10.3847/1538-4357/adfecb}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {167}, shortjournal = {The Astrophys. J.}, title = {Transiting planetary debris near the roche limit of a white dwarf on a 4.97 hr orbit—and its vanishing}, volume = {992}, year = {2025}, }
• (2025). Transport of mirror mode structures through saturn’s magnetopause reconnection. ApJ, 992(2), 166. (www)

  @article{ , abstract = {Magnetopause reconnection plays a significant role in transferring plasma and energy from the solar wind to planetary magnetospheres. Using a Cassini measurement, we reported a magnetopause reconnection at Saturn, identified by the Hall magnetic field and the mixture of magnetosheath electron population and magnetosphere electron population near the X-line. Then, the mirror mode (MM) structures are identified both in the magnetosheath and the magnetosphere. Further analysis suggests that the MM structures were generated in the magnetosheath and traveled across the magnetopause. We infer that MM structures enter the magnetosphere through the magnetopause reconnection. This result provides a possible source for the MM structures in the magnetosphere. These observations and analyses also help to further understand the influence of Saturn’s magnetopause reconnection on the magnetosphere dynamics.}, archive = {J_ApJ}, author = {S. B. Xu and S. Y. Huang and Z. G. Yuan and K. Jiang and H. H. Wu and J. Zhang and Z. Wang and Q. Y. Xiong and R. T. Lin}, doi = {10.3847/1538-4357/ae08af}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {166}, shortjournal = {The Astrophys. J.}, title = {Transport of mirror mode structures through saturn’s magnetopause reconnection}, volume = {992}, year = {2025}, }
• (2025). Reexamining the power-law relationship between global solar X-ray luminosity and total unsigned magnetic flux. ApJ, 992(2), 165. (www)

  @article{ , abstract = {The mechanism heating the solar corona remains unclear but is generally hypothesized to involve magnetic fields. One probe of this hypothesis is a statistical study relating coronal emission to magnetic flux. A. A. Pevtsov et al. conducted such a survey relating X-ray luminosity ( L X ) to unsigned photospheric magnetic flux (Φ m ) for a variety of heated plasmas, ranging from solar quiet regions to T Tauri stars. They reported that a power-law relationship, {L}_{{\rm{X}}}\sim {{\rm{\Phi }}}_{m}^{1.15} , described the entire collection but found that the subset from solar disk–integrated flux was better fit by a broken power law. Several parameters entering the calculations of L X and Φ m have the potential to impact this analysis. The present study uses more recent data to reanalyze the flux–luminosity relationship for the full solar disk and examines its dependence on parameters. We find the most significant effects from two parameters: the cutoff field strength used in computation of Φ m and the range of wavelengths defining L X . We find further that lower choices of cutoff yield a broken power law, while an optimal choice yields a single power law and minimizes the fitting residual. The critical cutoff is well above the magnetogram noise level, suggesting that weaker fields may not contribute significantly to the X-ray corona. We also find that L X defined by decreasing wavelength ranges requires an increasing critical cutoff. The resulting power-law indices vary, but all fall around 1.2.}, archive = {J_ApJ}, author = {Keiji Yoshimura and Aki Takeda and Dana W. Longcope}, doi = {10.3847/1538-4357/ae0a54}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {165}, shortjournal = {The Astrophys. J.}, title = {Reexamining the power-law relationship between global solar X-ray luminosity and total unsigned magnetic flux}, volume = {992}, year = {2025}, }
• (2025). Development of turbulence in postshock regions. ApJ, 992(2), 164. (www)

  @article{ , abstract = {Supersonic isothermal turbulence is ubiquitous in the interstellar medium. This work presents high-resolution A REPO hydrodynamical simulations of isolated shocks moving through supersonic turbulence to study the development and evolution of turbulence in the pre- and postshock regions. We find that shocks can amplify turbulent energy in the postshock region while inducing a preferential orientation for the vorticity. This results in the creation of anisotropic turbulence in the postshock region. Turbulent energy and dissipation are also strongly enhanced near the shock front. By applying typical scalings from the cold neutral medium to simulations, we find that shocks moving into turbulence on the scale of superbubbles can generate compressive flows on the order of 10 3 M ⊙ Myr –1 . Our results also show good agreement with related studies on turbulent fluctuations generated by shocks in pure fluid mechanics.}, archive = {J_ApJ}, author = {Michael M. Foley and Philip Mocz and Blakesley Burkhart and Lars Hernquist and Alyssa Goodman}, doi = {10.3847/1538-4357/adfa19}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {164}, shortjournal = {The Astrophys. J.}, title = {Development of turbulence in postshock regions}, volume = {992}, year = {2025}, }
• (2025). Breaking gyrochronology through the collapse of coronal winds. ApJ, 992(2), 163. (www)

  @article{ , abstract = {Gyrochronology, a method for dating aged field stars (≳a few Gyr) based on their rotation rate, has recently been shown to fail for many stars older than the Sun. The explanation most often put forth is that a shutdown or mode change in the stellar dynamo leads to a sharp decrease in angular momentum loss in magnetized coronal winds. In this paper, we explore an alternate possibility, namely, a collapse of the wind itself through a reduction of coronal heating. We show that in the low coronal temperature ( T 0 ) limit, even at solar-like low rotation rates (Ω) and coronal magnetic field strength ( B r 0 ), magnetocentrifugal effects are important and preclude expression of the mass and angular momentum loss rates as power laws of T 0 or Ω when T 0 drops below ≃1.5 MK. Mass loss is found to scale linearly with power input into the wind at all coronal temperatures. Introducing an ad hoc power-law relationship {T}_{0}\propto {B}_{r0}^{\sigma } while retaining the “standard” dynamo relationship B r 0 ∝ Ω, we show that reproducing the observed break in gyrochronology requires an exponent σ ≳ 1.5, which is associated with a drop by over 3 orders of magnitude in power input into the quiet corona. This appears physically unrealistic, given current observations of chromospheric and coronal nonthermal emission in aged solar-type stars.}, archive = {J_ApJ}, author = {Michaël Lévesque and Paul Charbonneau}, doi = {10.3847/1538-4357/ae03b0}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {163}, shortjournal = {The Astrophys. J.}, title = {Breaking gyrochronology through the collapse of coronal winds}, volume = {992}, year = {2025}, }
• (2025). Impulsive mixing of stellar populations in dwarf spheroidal galaxies. ApJ, 992(2), 162. (www)

  @article{ , abstract = {We study the response of mono-energetic stellar populations with initially isotropic kinematics to impulsive and adiabatic changes to an underlying dark matter potential. Half-light radii expand and velocity dispersions decrease as enclosed dark matter is removed. The details of this expansion and cooling depend on the timescale on which the underlying potential changes. In the adiabatic regime, the product of half-light radius and average velocity dispersion is conserved. We show that the stellar populations maintain centrally isotropic kinematics throughout their adiabatic evolution, and their densities can be approximated by a family of analytical radial profiles. Metallicity gradients within the galaxy flatten as dark matter is slowly removed. In the case of strong impulsive perturbations, stellar populations develop power-law-like density tails with radially biased kinematics. We show that the distribution of stellar binding energies within the dark matter halo substantially widens after an impulsive perturbation, no matter the sign of the perturbation. This allows initially energetically separated stellar populations to mix, to the extent that previously chemo-dynamically distinct populations may masquerade as a single population with large metallicity and energy spread. Finally, we show that in response to an impulsive perturbation, stellar populations that are deeply embedded in cored dark matter halos undergo a series of damped oscillations before reaching a virialized equilibrium state, driven by inefficient phase mixing in the harmonic potentials of cored halos. This slow return to equilibrium adds substantial systematic uncertainty to dynamical masses estimated from Jeans modeling or the virial theorem.}, archive = {J_ApJ}, author = {Raphaël Errani and Matthew G. Walker and Simon Rozier and Jorge Peñarrubia and Julio F. Navarro}, doi = {10.3847/1538-4357/adfa27}, journal = {The Astrophysical Journal}, month = {10}, number = {2}, pages = {162}, shortjournal = {The Astrophys. J.}, title = {Impulsive mixing of stellar populations in dwarf spheroidal galaxies}, volume = {992}, year = {2025}, }
• (2025). Erratum: “Measuring star formation rates in the milky way from hi-GAL 70 μm observations” (2025, ApJ, 980, 216). ApJ, 992(1), 161. (www)

  @article{ , archive = {J_ApJ}, author = {Davide Elia and Neal J. Evans and Juan D. Soler and Francesco Strafella and Eugenio Schisano and Sergio Molinari and Andrea Giannetti and Sudeshna Patra}, doi = {10.3847/1538-4357/ae0723}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {161}, shortjournal = {The Astrophys. J.}, title = {Erratum: “Measuring star formation rates in the milky way from hi-GAL 70 μm observations” (2025, ApJ, 980, 216)}, volume = {992}, year = {2025}, }
• (2025). Erratum: “Chemical differentiation of planets: A core issue” (2022, ApJ, 924, 83). ApJ, 992(1), 160. (www)

  @article{ , archive = {J_ApJ}, author = {Hervé Toulhoat and Viacheslav Zgonnik}, doi = {10.3847/1538-4357/ae0939}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {160}, shortjournal = {The Astrophys. J.}, title = {Erratum: “Chemical differentiation of planets: A core issue” (2022, ApJ, 924, 83)}, volume = {992}, year = {2025}, }
• (2025). Erratum: “Meterwavelength single pulse polarimetric emission survey. VI. toward understanding the phenomenon of pulsar polarization in partially screened vacuum gap model” (2023, ApJ, 952, 151). ApJ, 992(1), 159. (www)

  @article{ , archive = {J_ApJ}, author = {Dipanjan Mitra and George I. Melikidze and Rahul Basu}, doi = {10.3847/1538-4357/ae0a56}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {159}, shortjournal = {The Astrophys. J.}, title = {Erratum: “Meterwavelength single pulse polarimetric emission survey. VI. toward understanding the phenomenon of pulsar polarization in partially screened vacuum gap model” (2023, ApJ, 952, 151)}, volume = {992}, year = {2025}, }
• (2025). TiDES: The 4MOST time domain extragalactic survey. ApJ, 992(1), 158. (www)

  @article{ , abstract = {The Time Domain Extragalactic Survey (TiDES) conducted on the 4 m Multi-Object Spectroscopic Telescope will perform spectroscopic follow-up of extragalactic transients discovered in the era of the NSF-DOE Vera C. Rubin Observatory. TiDES will conduct a 5 yr survey, covering \gt 14,000\,\mathrm{square}\,\mathrm{degrees} , and use around 250,000 fibre hours to address three main science goals: (i) spectroscopic observations of >30,000 live transients, (ii) comprehensive follow-up of >200,000 host galaxies to obtain redshift measurements, and (iii) repeat spectroscopic observations of active galactic nuclei to enable reverberation mapping studies. The live spectra from TiDES will be used to reveal the diversity and astrophysics of both normal and exotic supernovae across the luminosity-timescale plane. The extensive host-galaxy redshift campaign will allow exploitation of the larger sample of supernovae and improve photometric classification, providing the largest-ever sample of SNe Ia, capable of a sub-2% measurement of the equation-of-state of dark energy. Finally, the TiDES reverberation mapping experiment of 700–1000 AGN will complement the SN Ia sample and extend the Hubble diagram to z ∼ 2.5.}, archive = {J_ApJ}, author = {C. Frohmaier and M. Vincenzi and M. Sullivan and S.F. Hönig and M. Smith and H. Addison and T. Collett and G. Dimitriadis and R. S. Ellis and P. Gandhi and O. Graur and I. Hook and L. Kelsey and Y.-L. Kim and C. Lidman and K. Maguire and L. Makrygianni and B. Martin and A. Möller and R. C. Nichol and M. Nicholl and P. Schady and B. D. Simmons and S. J. Smartt and E. Tempel and P. Wiseman and the LSST Dark Energy Science Collaboration}, doi = {10.3847/1538-4357/adff4e}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {158}, shortjournal = {The Astrophys. J.}, title = {TiDES: The 4MOST time domain extragalactic survey}, volume = {992}, year = {2025}, }
• (2025). Lopsided and bulging distribution of satellites around paired halos. i. observational measurements and comparison with halo-based models. ApJ, 992(1), 157. (www)

  @article{ , abstract = {We investigate the angular distribution of satellite galaxies in and around pairs of galaxy groups in the Sloan Digital Sky Survey (SDSS) and compare the results with the satellite distribution in pairs of dark matter halos by constructing mock catalogs that account for the same selection effects as the observational sample. We find that the angular distribution of satellites in both SDSS and the mock catalog exhibits a pronounced tendency toward lopsidedness, with satellites preferentially located between the two central galaxies. Additionally, there is a significant bulging distribution characterized by a higher concentration of satellites along the line connecting the two centrals compared to those found perpendicular to it. The lopsided and bulging distributions strengthen as pair separation and halo mass increase. The mock catalog successfully reproduces the observational results across all cases considered. We find that the lopsided and bulging distribution of satellites can largely be explained by overlapping two randomly selected halos matched in mass to the actual halo pairs, along with their surrounding satellite distribution, provided that the alignment between the orientations of the halos and the line connecting the halo pairs is taken into account. This suggests that the angular distribution of satellites is a natural consequence of the formation and evolution of large-scale structure in a Λ cold dark matter universe, eliminating the need to introduce other physical origins.}, archive = {J_ApJ}, author = {Yanhan Guo and Qinglin Ma and Cheng Li}, doi = {10.3847/1538-4357/ae00c3}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {157}, shortjournal = {The Astrophys. J.}, title = {Lopsided and bulging distribution of satellites around paired halos. i. observational measurements and comparison with halo-based models}, volume = {992}, year = {2025}, }
• (2025). HAWC performance enhanced by machine learning in gamma-hadron separation. ApJ, 992(1), 156. (www)

  @article{ , abstract = {Improving gamma-hadron separation is one of the most effective ways to enhance the performance of ground-based gamma-ray observatories. With more than a decade of continuous operation, the High-Altitude Water Cherenkov (HAWC) Observatory has contributed significantly to high-energy astrophysics. To further leverage its rich data set, we introduce a machine learning approach for gamma-hadron separation. A multilayer perceptron shows the best performance, surpassing traditional and other machine learning–based methods. This approach shows a notable improvement in the detector’s sensitivity, supported by results from both simulated and real HAWC data. In particular, it achieves a 19% increase in significance for the Crab Nebula, commonly used as a benchmark. These improvements highlight the potential of machine learning to significantly enhance the performance of HAWC and provide a valuable reference for ground-based observatories, such as the Large High Altitude Air Shower Observatory and the upcoming Southern Wide-field Gamma-ray Observatory.}, archive = {J_ApJ}, author = {R. Alfaro and C. Alvarez and A. Andrés and E. Anita-Rangel and M. Araya and J. C. Arteaga-Velázquez and D. Avila Rojas and H. A. Ayala Solares and R. Babu and P. Bangale and E. Belmont-Moreno and A. Bernal and T. Capistrán and A. Carramiñana and F. Carreón and S. Casanova and U. Cotti and E. De la Fuente and D. Depaoli and P. Desiati and N. Di Lalla and R. Diaz Hernandez and M. A. DuVernois and J. C. Díaz-Vélez and K. Engel and T. Ergin and C. Espinoza and K. L. Fan and N. Fraija and S. Fraija and J. A. García-González and F. Garfias and N. Ghosh and A. Gonzalez Muñoz and M. M. González and J. A. González and J. A. Goodman and S. Groetsch and J. P. Harding and S. Hernández-Cadena and I. Herzog and D. Huang and P. Hüntemeyer and A. Iriarte and S. Kaufmann and D. Kieda and K. Leavitt and J. Lee and H. León Vargas and J. T. Linnemann and A. L. Longinotti and G. Luis-Raya and K. Malone and O. Martinez and J. Martínez-Castro and J. A. Matthews and P. Miranda-Romagnoli and P. E. Mirón-Enriquez and J. A. Montes and J. A. Morales-Soto and E. Moreno and M. Najafi and A. Nayerhoda and L. Nellen and N. Omodei and M. Osorio and E. Ponce and Y. Pérez Araujo and E. G. Pérez-Pérez and C. D. Rho and A. Rodriguez Parra and D. Rosa-González and M. Roth and H. Salazar and A. Sandoval and J. Serna-Franco and A. J. Smith and Y. Son and R. W. Springer and O. Tibolla and K. Tollefson and I. Torres and R. Torres-Escobedo and E. Varela and L. Villaseñor and X. Wang and Z. Wang and I. J. Watson and H. Wu and S. Yu and H. Zhou and C. de León and (HAWC Collaboration)}, doi = {10.3847/1538-4357/ae0186}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {156}, shortjournal = {The Astrophys. J.}, title = {HAWC performance enhanced by machine learning in gamma-hadron separation}, volume = {992}, year = {2025}, }
• (2025). The parallel ionizing emissivity survey (PIE). i. survey design and selection of candidate lyman continuum leakers at 3.1 < z < 3.5. ApJ, 992(1), 155. (www)

  @article{ , abstract = {We present the survey design and initial results from the Parallel Ionizing Emissivity (PIE) survey. PIE is a large Hubble Space Telescope survey designed to detect Lyman continuum (LyC) emitting galaxies at 3.1 < z < 3.5 and stack their images in order to measure average LyC escape fractions as a function of galaxy properties. PIE has imaged 37 independent fields in three filters (F336W, F625W, and F814W), of which 18 are observed with a fourth band (F475W) from the accompanying PIE+ program. We use photometric colors to select candidate Lyman break galaxies (LBGs) at 3.1 < z < 3.5, which can be followed up using ground-based spectrographs to confirm their redshifts. Unlike previous surveys, we use many independent fields to remove biases caused by correlated absorption in the intergalactic medium (IGM). In this paper, we describe the survey design, photometric measurements, and the use of mock galaxy samples to optimize our color selection. With three filters, we can select a galaxy sample of which ≈90% are LBGs and over 30% lie in the 3.1 < z < 3.5 range for which we can detect uncontaminated LyC emission in F336W. We also use mock IGM sight lines to measure the expected transmission of the IGM, which will allow us to determine escape fractions from our stacked galaxies. We color-select ≈1400 galaxies, and predict that this includes ≈80 LyC-emitting galaxies and ≈500 that we can use in stacking. Finally, we present the Keck/LRIS spectrum of a galaxy at z ≈ 2.99, demonstrating that we can confirm the redshifts of z ∼ 3 galaxies from the ground.}, archive = {J_ApJ}, author = {Alexander Beckett and Marc Rafelski and Claudia Scarlata and Wanjia Hu and Keunho Kim and Ilias Goovaerts and Matthew A. Malkan and Wayne Webb and Harry Teplitz and Matthew Hayes and Vihang Mehta and Anahita Alavi and Andrew J. Bunker and Annalisa Citro and Nimish Hathi and Alaina Henry and Alexandra Le Reste and Alessia Moretti and Michael J. Rutkowski and Maxime Trebitsch and Anita Zanella}, doi = {10.3847/1538-4357/ae0291}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {155}, shortjournal = {The Astrophys. J.}, title = {The parallel ionizing emissivity survey (PIE). i. survey design and selection of candidate lyman continuum leakers at 3.1 < z < 3.5}, volume = {992}, year = {2025}, }
• (2025). Tidal heating in detached double white dwarf binaries. ApJ, 992(1), 154. (www)

  @article{ , abstract = {Short-period ( P < 1 hr orbits) detached double white dwarf binary (DWDB) components identified with transient surveys (e.g., SDSS, Zwicky Transient Facility, hereafter ZTF) have hot surface temperatures (>10,000 K) and observed radii a factor of 2 larger than completely degenerate white dwarfs. We formulate tidal heating in helium composition, extremely low-mass white dwarf components of detached DWDBs, which reach mass transfer within a Hubble time. We combine a mass–radius relation that varies with surface temperature and the equilibrium tidal friction model of Hut 1981, where the additional orbital energy loss from tidal friction is accounted for by increases in the primary surface temperature, and hence increasing radius. Applying this heating model to the current sample of binaries with ZTF, we predict temperature increases from the present day of up to ∼40% before the onset of mass transfer. We find that helium white dwarfs are generically hot and large at the onset of mass transfer, even for the oldest DWDBs whose components can cool to be degenerate by the present day. In the population of Galactic DWDBs, we find that the onset of mass transfer should occur at orbital periods as long as 1000 s (17 minutes), or binary gravitational-wave frequency of 2 mHz. This is over 3 times longer than periods expected for degenerate white dwarfs (5 minutes). Since mass transferring DWDBs are progenitors for a variety of transients and stellar populations, e.g., RCrB stars, AM CVn binaries, so-called Type .Ia supernova, the finite temperature of donor white dwarfs should be taken into account.}, archive = {J_ApJ}, author = {Lucy O. McNeill and Ryosuke Hirai}, doi = {10.3847/1538-4357/ae045f}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {154}, shortjournal = {The Astrophys. J.}, title = {Tidal heating in detached double white dwarf binaries}, volume = {992}, year = {2025}, }
• (2025). QZO: A catalog of 5 million quasars from the zwicky transient facility. ApJ, 992(1), 153. (www)

  @article{ , abstract = {Machine learning methods are well established in the classification of quasars (QSOs). However, the advent of light-curve observations adds a great amount of complexity to the problem. Our goal is to use the Zwicky Transient Facility (ZTF) to create a catalog of QSOs. We process the ZTF DR20 light curves with a transformer artificial neural network and combine different surveys with extreme gradient boosting. Based on ZTF g -band and Wide-field Infrared Survey Explorer (WISE) observations, we find 4,849,574 objects classified as QSOs with confidence higher than 90% (QZO). We robustly classify objects fainter than the 5 σ signal-to-noise ratio (SNR) limit at g = 20.8 by requiring g < n obs /80 + 20.375. For 33% of QZO objects, with available WISE data, we publish redshifts with estimated error Δ z /(1 + z ) = 0.14. We find that ZTF classification is superior to the Pan-STARRS static bands, and on par with WISE and Gaia measurements, but the light curves provide the most important features for QSO classification in the ZTF data set. Using ZTF g -band data with at least 100 observational epochs per light curve, we obtain a 97% F1 score for QSOs. We find that with 3 day median cadence, a survey time span of at least 900 days is required to achieve a 90% QSO F1 score. However, one can obtain the same score with a survey time span of 1800 days and the median cadence prolonged to 12 days.}, archive = {J_ApJ}, author = {S. J. Nakoneczny and M. J. Graham and D. Stern and G. Helou and S. G. Djorgovski and E. C. Bellm and T. X. Chen and R. Dekany and A. Drake and A. A. Mahabal and T. A. Prince and R. Riddle and B. Rusholme and N. Sravan}, doi = {10.3847/1538-4357/adf4e4}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {153}, shortjournal = {The Astrophys. J.}, title = {QZO: A catalog of 5 million quasars from the zwicky transient facility}, volume = {992}, year = {2025}, }
• (2025). GWSkyNet-multi. II. an updated machine learning model for rapid classification of gravitational-wave events. ApJ, 992(1), 152. (www)

  @article{ , abstract = {Multimessenger observations of gravitational waves and electromagnetic emission from compact object mergers offer unique insights into the structure of neutron stars, the formation of heavy elements, and the expansion rate of the Universe. With the LIGO–Virgo–KAGRA (LVK) gravitational-wave detectors currently in their fourth observing run (O4), it is an exciting time for detecting these mergers. However, assessing whether to follow up a candidate gravitational-wave event given limited telescope time and resources is challenging; the candidate can be a false alert due to detector glitches, or may not have any detectable electromagnetic counterpart even if it is real. GWSkyNet-Multi is a machine learning model developed to facilitate follow-up decisions by providing real-time classification of candidate events, using localization information released in LVK rapid public alerts. Here we introduce GWSkyNet-Multi II , an updated model targeted toward providing more robust and informative predictions during O4 and beyond. Specifically, the model now provides normalized probability scores and associated uncertainties for each of the four corresponding source categories released by the LVK: glitch, binary black hole, neutron star–black hole, and binary neutron star. Informed by explainability studies of the original model, the updated model architecture is also significantly simplified, including replacing input images with intuitive summary values that are more interpretable. For significant event alerts issued during O4a and O4b, GWSkyNet-Multi II produces a prediction that is consistent with the updated LVK classification for 93% of events. The updated model can be used by the community to help make time-critical follow-up decisions.}, archive = {J_ApJ}, author = {Nayyer Raza and Man Leong Chan and Daryl Haggard and Ashish Mahabal and Jess McIver and Audrey Durand and Alexandre Larouche and Hadi Moazen}, doi = {10.3847/1538-4357/adfc58}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {152}, shortjournal = {The Astrophys. J.}, title = {GWSkyNet-multi. II. an updated machine learning model for rapid classification of gravitational-wave events}, volume = {992}, year = {2025}, }
• (2025). Hidden figures of globular clusters: Integrated stellar populations impacted by hot subdwarfs. ApJ, 992(1), 151. (www)

  @article{ , abstract = {Globular clusters (GCs) are fundamental for understanding the integrated light of old stellar populations and galaxy assembly processes. However, the role of hot, evolved stars, such as horizontal branch (HB), extreme HB, and blue stragglers, remains poorly constrained. These stars are often underrepresented or entirely excluded from stellar population models, despite their dominant contribution to the ultraviolet (UV) flux. Their presence can bias age estimates by mimicking the spectral signatures of younger populations. We examined the impact of evolved hot stars on the models using two well-studied Galactic GCs with high-quality Hubble Space Telescope photometry and integrated spectra from the International Ultraviolet Explorer and the Blanco Telescope. NGC 2808 and NGC 7089 (M 2) have extended HBs and are proxies for old stellar populations. Integrated spectra were constructed using a color magnitude diagram–based (CMD-based) method, matching observed stars to evolutionary phases and then to appropriate synthetic stellar libraries, enabling the HB morphology to be taken into account. Our findings show that the inclusion of evolved hot stars significantly improves the agreement between the model and observed spectra from the UV to the optical. The inclusion of these phases reduced the residuals in spectral comparisons. Our results reinforce that comprehensive stellar population models incorporating evolved hot components are essential to accurately date unresolved systems and to robustly trace formation histories of extragalactic galaxies.}, archive = {J_ApJ}, author = {Thayse A. Pacheco and Paula R. T. Coelho and Lucimara P. Martins and Ricardo P. Schiavon and Erik V. R. de Lima and Marcos P. Diaz and Domenico Nardiello and Ronaldo S. Levenhagen and Rogério Riffel and Charles J. Bonatto and Ana L. Chies-Santos}, doi = {10.3847/1538-4357/adff5f}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {151}, shortjournal = {The Astrophys. J.}, title = {Hidden figures of globular clusters: Integrated stellar populations impacted by hot subdwarfs}, volume = {992}, year = {2025}, }
• (2025). White dwarfs with infrared excess in the HET dark energy experiment. ApJ, 992(1), 150. (www)

  @article{ , abstract = {White dwarfs with infrared excess emission provide a window into the late stages of stellar evolution and the dynamics of circumstellar environments. Using data from the Hobby–Eberly Telescope Dark Energy Experiment, we characterized 30 white dwarfs exhibiting infrared excess, including 29 DA and 1 DB stars. While an infrared excess can arise from dusty disks or cool (sub)stellar companions, our sample is limited to stellar companions, due to our selection based on SDSS photometry, which is sensitive to excess emission at wavelengths λ < 1 μ m. Our sample contains 22 newly identified excess sources not previously reported in the literature. Spectroscopic observations are available for 10 sources via SDSS, of which only 8 have prior spectroscopic classifications in the literature. In this paper, we present the determination of the effective temperature and surface gravity of these white dwarfs. We used the Balmer line profiles to compare with current atmospheric models in order to determine the photospheric parameters of the white dwarfs, minimizing contamination introduced by the infrared source. We used photometric data from the SDSS and the Gaia mission to resolve the degeneracies between hot and cold solutions from spectroscopy, constraining the photospheric parameters. These results help refine our understanding of white dwarf evolution in binary systems, focusing on stellar companions that cause the infrared excess. This study contributes to identifying systems with potential substellar companions or unresolved stellar partners, adding to the growing effort to map out the fate of planetary systems after their host stars evolve beyond the main sequence.}, archive = {J_ApJ}, author = {Rudy A. Morales and Barbara G. Castanheira and Jayden Blanchard and Detlev Koester and Péter Németh and S. O. Kepler and Erin Mentuch Cooper and Karl Gebhardt}, doi = {10.3847/1538-4357/adff84}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {150}, shortjournal = {The Astrophys. J.}, title = {White dwarfs with infrared excess in the HET dark energy experiment}, volume = {992}, year = {2025}, }
• (2025). On the eddington capture surface around spherically symmetric compact objects with separable luminosity distributions. ApJ, 992(1), 149. (www)

  @article{ , abstract = {Radiation exerts pressure, and therefore it is possible for an intensely bright object to balance the gravitational force near a massive compact object. General relativity demonstrates that this balance occurs for super-Eddington luminosities at a finite distance from the center of the mass. These equilibrium positions are referred to as Eddington capture surfaces (ECSs). At the ECSs, particles can collect in a thin shell, balanced between the inward curvature of spacetime and the outward flow of radiation. We adopt spherical symmetry but otherwise leave the metric functions generalized. This approach allows us to study the ECSs under the effect of arbitrary spherically symmetric metrics. We adopt a separable luminosity function that depends on both the radial direction and the angular coordinates over the surface of the star. We demonstrate that the morphology of an ECS varies depending on the angular luminosity distribution and can even split into multiple, separate, disconnected equilibrium surfaces. The ECS phenomenon is closely related to type I photospheric radius expansion X-ray bursts.}, archive = {J_ApJ}, author = {Noah Monk and Adam Rogers}, doi = {10.3847/1538-4357/ae00c7}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {149}, shortjournal = {The Astrophys. J.}, title = {On the eddington capture surface around spherically symmetric compact objects with separable luminosity distributions}, volume = {992}, year = {2025}, }
• (2025). Tracing magnetic field in super-alfvénic turbulence with gradient technique. ApJ, 992(1), 148. (www)

  @article{ , abstract = {Super-Alfvénic turbulence is important for many astrophysical objects, particularly galaxy clusters. In this paper, we explore the accuracy of synchrotron intensity gradients and X-ray intensity gradients to map magnetic fields in super-Alfvénic turbulence for a set of astrophysically relevant parameters of turbulent driving. Analyzing our synthetic observations, we report a good accuracy for both techniques. Our results are suggestive that other types of gradient technique can be successfully employed to trace magnetic fields within super-Alfvénic subsonic turbulence.}, archive = {J_ApJ}, author = {Ka Wai Ho and A. Lazarian}, doi = {10.3847/1538-4357/ae01a3}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {148}, shortjournal = {The Astrophys. J.}, title = {Tracing magnetic field in super-alfvénic turbulence with gradient technique}, volume = {992}, year = {2025}, }
• (2025). Bondi-like accretion flow dynamics: The role of gravitational potential. ApJ, 992(1), 147. (www)

  @article{ , abstract = {The formation of massive black holes and their coevolution with host galaxies are pivotal areas of modern astrophysics. Spherical accretion onto a central point mass serves as a foundational framework in cosmological simulations, semi-analytical models, and observational studies. In this paper, we extend the classical spherical accretion model by incorporating the gravitational potential of host galaxies, including contributions from stellar components and dark matter (DM) halos. Numerical solutions spanning scales from parsecs down to ∼10 r s reveal that the flow structure is highly sensitive to the mass and size of the DM halo. Adding a small amount of angular momentum to the accreting gas demonstrates that such flows resemble spherical Bondi accretion, with mass accretion rates converging toward the Bondi rate. We find that the low angular momentum flow resembles the spherical Bondi flow, and its mass accretion rate approaches the Bondi accretion rate. Remarkably, due to the presence of DM, the mass accretion rate increases by more than ∼100% compared to analogous hydrodynamic solutions without DM. These findings underscore the critical role of stellar and DM gravitational potentials in shaping the dynamics and accretion rates of quasi-spherical flows, providing new insights into astrophysical accretion processes.}, archive = {J_ApJ}, author = {Razieh Ranjbar and Héctor R. Olivares-Sánchez and Shahram Abbassi}, doi = {10.3847/1538-4357/ae032c}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {147}, shortjournal = {The Astrophys. J.}, title = {Bondi-like accretion flow dynamics: The role of gravitational potential}, volume = {992}, year = {2025}, }
• (2025). Thermal electrons in the radio afterglow of relativistic tidal disruption event ZTF22aaajecp/AT 2022cmc. ApJ, 992(1), 146. (www)

  @article{ , abstract = {A tidal disruption event (TDE) occurs when a star travels too close to a supermassive black hole. In some cases, accretion of the disrupted material onto the black hole launches a relativistic jet. In this paper, we present a long-term observing campaign to study the radio and submillimeter emission associated with the fifth jetted/relativistic TDE: AT 2022cmc. Our campaign reveals a long-lived counterpart. We fit three different models to our data: a nonthermal jet, a spherical outflow consisting of both thermal and nonthermal electrons, and a jet with thermal and nonthermal electrons. We find that the data are best described by a relativistic spherical outflow propagating into an environment with a density profile following R −1.8 . Comparison of AT 2022cmc to other TDEs finds agreement in the density profile of the environment but also that AT 2022cmc is twice as energetic as the other well-studied relativistic TDE, Swift J1644. Our observations of AT 2022cmc allow a thermal electron population to be inferred for the first time in a jetted transient, providing new insights into the microphysics of relativistic transients jets.}, archive = {J_ApJ}, author = {Lauren Rhodes and Ben Margalit and Joe S. Bright and Hannah Dykaar and Rob Fender and David A. Green and Daryl Haggard and Assaf Horesh and Alexander J. van der Horst and Andrew K. Hughes and Kunal Mooley and Itai Sfaradi and David Titterington and David Williams-Baldwin}, doi = {10.3847/1538-4357/ae03b6}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {146}, shortjournal = {The Astrophys. J.}, title = {Thermal electrons in the radio afterglow of relativistic tidal disruption event ZTF22aaajecp/AT 2022cmc}, volume = {992}, year = {2025}, }
• (2025). New near-infrared coronal lines observed during the 2019 total solar eclipse. ApJ, 992(1), 145. (www)

  @article{ , abstract = {We report on a further analysis of the Airborne Infrared Spectrometer (AIR-Spec) observations from the 2019 July 2 total eclipse and present the identifications of three new coronal lines from Fe x , Si xi , and Si vi in AIR-Spec’s 1.87–1.99 μ m band. The new lines were predicted to be observable but were not observed previously in the corona. The identifications are confirmed on the basis of observed and expected line wavelengths and radiances. The observed wavelengths are very accurate, as confirmed by neutral H and He lines measured during the same observation. The predicted wavelengths are assessed by reviewing previous experimental data used to estimate the energies of these ions. We find discrepancies with several previous measurements. A reanalysis of Solar Ultraviolet Measurement of Emitted Radiation data corrects previous measurements and provides excellent agreement with the AIR-Spec values for Si xi . AIR-Spec was developed to survey the near-infrared (NIR) coronal spectrum from above Earth’s atmosphere, a critical first step in designing future balloonborne and spaceborne instrumentation to observe coronal plasma and magnetic fields using NIR emission lines. The reported results are also of interest for ground-based observatories, as the precise measurements of line wavelength enable observers to understand the nearby telluric spectrum and determine which lines can be used from the ground.}, archive = {J_ApJ}, author = {Jenna Samra and Giulio Del Zanna and Celeste Elizalde Flores and Chad Madsen and Edward DeLuca}, doi = {10.3847/1538-4357/ae046a}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {145}, shortjournal = {The Astrophys. J.}, title = {New near-infrared coronal lines observed during the 2019 total solar eclipse}, volume = {992}, year = {2025}, }
• (2025). Eclipsing millisecond pulsars with he star companions. ApJ, 992(1), 144. (www)

  @article{ , abstract = {Eclipsing millisecond pulsars (MSPs) are a type of pulsar binaries with close orbits (≲1.0 day). They are important objects for studying the accretion history of neutron stars (NSs), pulsar winds, and the origin of isolated MSPs, etc. Recently, a new eclipsing MSP, PSR J1928+1815, was discovered by the Five-hundred-meter Aperture Spherical radio Telescope. It is the first known pulsar with a He star companion, as suggested in Yang et al. The system features a short orbital period of ∼0.15 days and a relatively massive companion ≳1.0 M ⊙ . However, the origin of PSR J1928+1815 remains highly uncertain. In this paper, we investigated the formation of the new subclass of eclipsing MSPs containing (evolved) He star companions through the NS + He star channel. We found that if an NS binary undergoes subsequent mass-transfer phases following Case BA or Case BB, it may appear as an eclipsing MSP during the detached phase. Additionally, we obtained the initial parameter space for producing eclipsing MSPs with He star companions. Using the binary population synthesis approach, we estimated their birth rate to be ∼2.1–4.7 × 10 −4 yr −1 , corresponding to a total number of ∼220 systems in the Galaxy. Moreover, we concluded that PSR J1928+1815 may originate from the evolution of an NS + He star system with an initial orbital period of ∼0.1 days, which can undergo the Case BB mass transfer.}, archive = {J_ApJ}, author = {Yunlang Guo and Bo Wang and Xiangdong Li and Dongdong Liu and Wenshi Tang}, doi = {10.3847/1538-4357/ae057b}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {144}, shortjournal = {The Astrophys. J.}, title = {Eclipsing millisecond pulsars with he star companions}, volume = {992}, year = {2025}, }
• (2025). Possible first detection of gyroresonance emission from a coronal mass ejection in the middle corona. ApJ, 992(1), 143. (www)

  @article{ , abstract = {Routine measurements of the magnetic field of coronal mass ejections (CMEs) have been a key challenge in solar physics. Making such measurements is important both from a space weather perspective and for understanding the detailed evolution of the CME. In spite of significant efforts and multiple proposed methods, achieving this goal has not been possible to date. Here we report the first possible detection of gyroresonance emission from a CME. Assuming that the emission is happening at the third harmonic, we estimate that the magnetic field strength ranges from 7.9 to 5.6 G between 4.9 and 7.5 R ⊙ . We also demonstrate that this high magnetic field is not the average magnetic field inside the CME, but most probably is related to small magnetic islands, which are also being observed more frequently with the availability of high-resolution and high-quality white-light images.}, archive = {J_ApJ}, author = {Surajit Mondal and Bin Chen and Xingyao Chen and Sijie Yu and Dale Gary and Peijin Zhang and Marin M. Anderson and Judd D. Bowman and Ruby Byrne and Morgan Catha and Sherry Chhabra and Larry D’Addario and Ivey Davis and Jayce Dowell and Katherine Elder and Gregg Hallinan and Charlie Harnach and Greg Hellbourg and Jack Hickish and Rick Hobbs and David Hodge and Mark Hodges and Yuping Huang and Andrea Isella and Daniel C. Jacobs and Ghislain Kemby and John T. Klinefelter and Matthew Kolopanis and Nikita Kosogorov and James Lamb and Casey Law and Nivedita Mahesh and Brian O’Donnell and Kathryn Plant and Corey Posner and Travis Powell and Vinand Prayag and Andres Rizo and Andrew Romero-Wolf and Jun Shi and Greg Taylor and Jordan Trim and Mike Virgin and Akshatha Vydula and Sandy Weinreb and Scott White and David Woody and Thomas Zentmeyer}, doi = {10.3847/1538-4357/ae061f}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {143}, shortjournal = {The Astrophys. J.}, title = {Possible first detection of gyroresonance emission from a coronal mass ejection in the middle corona}, volume = {992}, year = {2025}, }
• (2025). The physical properties of four double-lined detached eclipsing binaries with similar components and third bodies from the LAMOST medium-resolution survey. ApJ, 992(1), 142. (www)

  @article{ , abstract = {The stellar model is still facing challenges in explaining the origin of low-mass stars and brown dwarfs. Double-lined detached eclipsing binaries with low-mass and similar components play an important astrophysical role in accurately deriving fundamental parameters, investigating stellar properties, and restricting theoretical stellar models of low-mass stars. Using high-precision light curves and Large Sky Area Multi-Object Fiber Spectroscopic Telescope spectra, we first obtained the fundamental parameters of the four detached binaries (NSVS 07453183, V644 Aur, V912 Per, and V1250 Tau). Except for V1250 Tau ( q sp ∼ 0.95), the mass ratios of the other three targets are almost equal to 1, which is consistent with the core fragmentation and dynamical capture theories of binary formation. The O − C curves of these systems based on current data exhibit cyclic variations, which is due to the light-travel time effect caused by the presence of a third body. Among them, the third body of V912 Per is likely to be a stellar black hole ({M}_{3}\sin {i}_{3}=12.57{M}_{\odot }) . The O − C diagram of NSVS 07453183 shows double-cycle oscillations, which means that it is perhaps a quadruple system. The third body of NSVS 07453183 is an M3-type main-sequence star based on third light analysis, and the fourth body maybe a brown dwarf. The obtained Hertzsprung–Russell diagram based on the Modules for Experiments in Stellar Astrophysics code suggested that the components of these four targets are main-sequence stars. These four targets will gradually form Algol-type binaries in the future, which are important systems for studying the reversal of the mass ratio.}, archive = {J_ApJ}, author = {Bin Zhang and Yi-Dan Gao and Chun-Qian Li and Xing-Hao Chen and Gang Zhao and Wen-Jun Xiao and Xu-Dong Zhang and Jing-Kun Zhao and Jia Zhang and Zhen Zhong}, doi = {10.3847/1538-4357/ae0620}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {142}, shortjournal = {The Astrophys. J.}, title = {The physical properties of four double-lined detached eclipsing binaries with similar components and third bodies from the LAMOST medium-resolution survey}, volume = {992}, year = {2025}, }
• (2025). Statistical analysis of ∼100 hz whistler-mode waves near the moon using ARTEMIS observations. ApJ, 992(1), 141. (www)

  @article{ , abstract = {Utilizing 11 yr of Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon’s Interaction with the Sun P1 and P2 observations from 2013 to 2023, we perform a comprehensive statistical analysis of ∼100 Hz whistler-mode waves near the Moon. The investigation focuses on waves in the unique lunar environment, characterized by the absence of a global magnetic field and the presence of localized crustal magnetic anomalies. We carefully investigate the spatial distribution, amplitude, and peak frequencies of these waves, including their dependence on solar wind speed ( V sw ), dynamic pressure ( P dyn ), and interplanetary magnetic field strength ( B tot ). The results show that the wave amplitudes are predominantly between 0.01 and 0.3 nT, with significant differences in the spatial distribution of the ∼100 Hz waves inside and outside the Earth’s magnetosphere. Magnetic connection to the lunar surface significantly enhances the wave occurrence rate, while strong crustal magnetic fields suppress it. Wave amplitude exhibits a positive correlation with P dyn , and peak frequency increases with B tot . These obtained distribution features and dependencies of lunar ∼100 Hz whistler-mode waves are valuable to improve the current understanding of wave generation mechanisms and the underlying contribution of wave–particle interactions in the lunar plasma environment.}, archive = {J_ApJ}, author = {Shaoting Cheng and Song Fu and Hui Zhang and Binbin Ni and Taifeng Jin and Yuequn Lou and Yaping Cheng and Longfei Jia and Xiaotong Yun and Shuyue Pang and Xiangyuan Tong and Qiongyue Zhang and Xin Ma}, doi = {10.3847/1538-4357/ae0714}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {141}, shortjournal = {The Astrophys. J.}, title = {Statistical analysis of ∼100 hz whistler-mode waves near the moon using ARTEMIS observations}, volume = {992}, year = {2025}, }
• (2025). Magnetohydrodynamic tests of galactic synchrotron depolarization. ApJ, 992(1), 140. (www)

  @article{ , abstract = {Synchrotron emission from cosmic-ray electrons accelerated in the Galactic magnetic field encodes information on the role of turbulence in the magnetized interstellar medium. Although synchrotron radiation is intrinsically highly polarized, the observed fractional polarization f = P / I is below 5% over most of the sky. Despite this marked depolarization, the remaining signal is highly aligned, with median scatter in polarization angle less than 15° within regions of 20° diameter on the sky. We use magnetohydrodynamic (MHD) simulations to determine the extent to which MHD turbulence can reproduce the observed pattern of substantial depolarization with minimal angular scatter. We evaluate both the synchrotron fractional polarization and polarization angle as projected through a suite of simulations with sonic Mach number 0.5\lt {{ \mathcal M }}_{{ \mathcal S }}\lt 6 and magnetic (Alfvén) Mach number 0.5\lt {{ \mathcal M }}_{{\rm{A}}}\lt 4 . Simulations with a weakly magnetized plasma and strongly supersonic flow ( {{ \mathcal M }}_{{\rm{A}}}=2 with 4\lt {{ \mathcal M }}_{{ \mathcal S }}\lt 6 ) match the observed high-latitude sky. The fit improves when the angle between the observer and the seed magnetic field is 15°–30° from perpendicular, in agreement with models of the local inclination angle of the large-scale Galactic magnetic field. Additional improvement occurs if the estimated brightness of the unpolarized Galactic synchrotron emission is reduced, either by subtracting an unpolarized extragalactic component from the observed radio maps or by applying a steeper spectra index when scaling the unpolarized synchrotron intensity from 408 MHz to 30 GHz.}, archive = {J_ApJ}, author = {Alan Kogut and David C. Collins}, doi = {10.3847/1538-4357/ae0a14}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {140}, shortjournal = {The Astrophys. J.}, title = {Magnetohydrodynamic tests of galactic synchrotron depolarization}, volume = {992}, year = {2025}, }
• (2025). Genesis of a confined x6.4 flare in a quadrupolar magnetic configuration. ApJ, 992(1), 139. (www)

  @article{ , abstract = {Both eruptive and confined flares—those having and lacking, respectively, an associated large-scale coronal mass ejection—are frequently observed in solar active regions (ARs). The physical mechanisms controlling the nature of these flares are poorly understood, requiring a detailed investigation of both the magnetic environment and the dynamic flare production process within the source region. Here we study a confined X6.4 flare with a failed filament eruption in AR 13590, observed by the SDO spacecraft on 2024 February 22. AR 13590 exhibited a quadrupolar magnetic configuration consisting of one central and two side arcades of low-lying loops, overlain by a fourth arcade of high-lying loops. A potential-field extrapolation contains a low-altitude null point at a height of approximately 5 Mm. This is a classic magnetic-breakout topology, except that the rising filament lay under one of the side arcades. The confined flare generated four ribbons located in all four of the major polarities, and proceeded in two phases, characterized by two successive stages of ribbon brightenings accompanied by forward and then reverse motion of the brightenings along the interior ribbons. We propose that the two phases represent breakout reconnection in the null region, which removed the flux ahead of the rising filament, followed by “anti-breakout” reconnection, corresponding to a reversed process as those flux systems evolved back toward the pre-eruption configuration. We discuss the implications of these observations for understanding how intense flares can occur without the expulsion of material from the solar corona.}, archive = {J_ApJ}, author = {Chunming Zhu and Joel T. Dahlin and C. Richard DeVore and Jiong Qiu and Maria D. Kazachenko and Vadim M. Uritsky}, doi = {10.3847/1538-4357/ae0297}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {139}, shortjournal = {The Astrophys. J.}, title = {Genesis of a confined x6.4 flare in a quadrupolar magnetic configuration}, volume = {992}, year = {2025}, }
• (2025). Selection of dwarf galaxies hosting active galactic nuclei: A measure of bias and contamination using unsupervised machine learning techniques. ApJ, 992(1), 138. (www)

  @article{ , abstract = {Identifying active galactic nuclei (AGNs) in dwarf galaxies is critical for understanding black hole formation but remains observationally challenging due to their low luminosities, metallicities, and star formation–driven emission that can obscure AGN signatures. Machine learning techniques, particularly unsupervised methods, offer new ways to address these challenges by uncovering patterns in complex, multiwavelength data. In this study, we apply Self-Organizing Maps (SOMs) to explore the spectral energy distribution (SED) manifold of dwarf galaxies and evaluate AGN selection biases across various diagnostics. We train a 51 × 51 SOM on 30,344 dwarf galaxies ( z < 0.055, M * < 10 9.5 M ⊙ ) from the NSA catalog using nine-band photometry spanning near-UV to mid-infrared. A set of 438 previously identified dwarf AGNs, selected via mid-infrared color, optical emission lines, X-ray, optical variability, and broad-line features, was mapped onto the SOM. AGNs identified by different methods occupy distinct and partially overlapping regions in SED space, reflecting biases related to host galaxy properties. Wide-field Infrared Survey Explorer (WISE)-selected AGNs are strongly concentrated in lower-mass regions and form two distinct clumps: one associated with bluer, starburst-like systems and the other with redder galaxies showing spectral features more typical of AGNs. This separation may help disentangle true AGN hosts from starburst contaminants in WISE-selected samples. Additionally, AGNs selected via various diagnostics tend to avoid regions of strong star formation, while a subset of lower-mass AGNs occupy SOM regions indicative of high AGN luminosity relative to their stellar content. Our results demonstrate the utility of manifold learning in refining AGN selection in the low-mass regime.}, archive = {J_ApJ}, author = {Sogol Sanjaripour and Archana Aravindan and Gabriela Canalizo and Shoubaneh Hemmati and Bahram Mobasher and Alison L. Coil and Barry C. Barish}, doi = {10.3847/1538-4357/ae0326}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {138}, shortjournal = {The Astrophys. J.}, title = {Selection of dwarf galaxies hosting active galactic nuclei: A measure of bias and contamination using unsupervised machine learning techniques}, volume = {992}, year = {2025}, }
• (2025). Confined circumstellar material as a dust formation site in type II supernovae. ApJ, 992(1), 137. (www)

  @article{ , abstract = {We propose a model for dust formation in Type II supernovae (SNe) interacting with confined circumstellar material (CSM), motivated by recent time-domain surveys that have revealed a substantial fraction of SN progenitors to be surrounded by CSM ejected shortly before core collapse. We simulate the pre-SN mass eruption and the resulting confined CSM using the open-source code CHIPS , and follow the subsequent evolution of the SN ejecta and its interaction with the CSM. We show that a cold dense shell (CDS) is formed at the radiative shock under a wide range of conditions and later undergoes rapid adiabatic cooling during free expansion, leading to efficient dust condensation. The resulting dust mass ranges from ∼10 −3 M ⊙ to 0.1 M ⊙ , depending on the mass and spatial extent of the CSM. We further calculate the infrared (IR) emission from the newly formed dust and find broad consistency with observations of SN 1998S. Notably, the IR light curve exhibits a rapid rise within ≲10 days, closely resembling that of kilonovae (KNe). This suggests that dust emission powered by confined CSM interaction may be also discovered in KN searches. Moreover, the high-density environment of the CDS may allow dust grains to grow to larger sizes, enhancing their survivability against destruction by reverse shocks propagating from the interstellar medium at later times.}, archive = {J_ApJ}, author = {Yuki Takei and Kunihito Ioka and Masaru Shibata}, doi = {10.3847/1538-4357/ae0466}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {137}, shortjournal = {The Astrophys. J.}, title = {Confined circumstellar material as a dust formation site in type II supernovae}, volume = {992}, year = {2025}, }
• (2025). A novel formation channel for supermassive black hole binaries in the early universe via primordial black holes. ApJ, 992(1), 136. (www)

  @article{ , abstract = {We present a novel formation channel for supermassive black hole (SMBH) binaries in the early Universe, driven by primordial black holes (PBHs). Using high-resolution hydrodynamical simulations, we explore the role of massive PBHs ( m BH ∼ 10 6 M ⊙ ) in catalyzing the formation of direct-collapse black holes (DCBHs), providing a natural in situ pathway for binary SMBH formation. PBHs enhance local overdensities, accelerate structure formation, and exert thermal feedback on the surrounding medium via accretion. Lyman–Werner radiation from accreting PBHs suppresses H 2 cooling, shifting the dominant gas coolant to atomic hydrogen. When combined with significant baryon–dark matter streaming velocities ( v b χ ≳ 0.8 σ b χ , where σ b χ is the rms streaming velocity), these effects facilitate the formation of dense, gravitationally unstable atomically cooling gas clouds in the PBH’s wake. These clouds exhibit sustained high inflow rates ( {\dot{M}}_{{\rm{infall}}}\gtrsim 0.1-0.01\,{M}_{\odot } yr −1 ), providing ideal conditions for DCBH formation from rapidly growing supermassive stars of ∼10 5 M ⊙ at redshift z ∼ 20–10. The resulting systems form SMBH binaries with initial mass ratios q\sim { \mathcal O }(0.1) and separations of ∼10 pc. Such PBH-DCBH binaries provide testable predictions for JWST and Atacama Large Millimeter/submillimeter Array, potentially explaining select high- z sources like little red dots, and represent gravitational-wave sources for future missions like LISA and TianQin—bridging early-Universe black hole physics, multimessenger astronomy, and dark matter theory.}, archive = {J_ApJ}, author = {Saiyang Zhang and Boyuan Liu and Volker Bromm}, doi = {10.3847/1538-4357/ae061c}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {136}, shortjournal = {The Astrophys. J.}, title = {A novel formation channel for supermassive black hole binaries in the early universe via primordial black holes}, volume = {992}, year = {2025}, }
• (2025). Cosmic-ray mass composition around the knee via principal component analysis. ApJ, 992(1), 135. (www)

  @article{ , abstract = {In this paper, we apply principal component analysis (PCA) to experimental data recorded by the KASCADE experiment to reconstruct the mass composition of cosmic rays around the knee region. A set of four extensive air shower parameters sensitive to the primary particle mass ( LCm , N μ , N e , and lateral shower age) was considered, whose coordinates were transformed into a new orthogonal basis that maximally captures the data variance. Based on the experimental distributions of the first two principal components (PCA0 versus PCA1) and full Monte Carlo simulations of the KASCADE array considering five types of primary particles (p, He, C, Si, and Fe) and three hadronic interaction models (EPOS-LHC, QGSjet-II-04, and SIBYLL 2.3d), we obtained the evolution of the abundance of each primary species as a function of energy, as well as the evolution of the mean logarithmic mass with energy. We found that the reconstruction of the mass composition resulting from this comprehensive analysis significantly reduces dependence on the hadronic interaction model used in the simulation process, even though the initial input parameters are model dependent. Moreover, the results support the idea that around the knee region, the abundance of the light component (protons) decreases, while the heavy component shows a slight increase. The evolution of \langle \mathrm{ln}(A)\rangle as a function of energy derived from this analysis shows excellent agreement with recent results from the LHAASO–KM2A experiment and aligns very well with the predictions of the data-driven Global Spline Fit model.}, archive = {J_ApJ}, author = {Nicusor Arsene}, doi = {10.3847/1538-4357/ae09a9}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {135}, shortjournal = {The Astrophys. J.}, title = {Cosmic-ray mass composition around the knee via principal component analysis}, volume = {992}, year = {2025}, }
• (2025). The ODYSSEUS survey. characterizing magnetospheric geometries and hotspot structures in t tauri stars. ApJ, 992(1), 134. (www)

  @article{ , abstract = {Magnetospheric accretion is a key process that shapes the inner disks of T Tauri stars, controlling mass and angular momentum evolution. It produces strong ultraviolet and optical emission that irradiates the planet-forming environment. In this work, we characterize the magnetospheric geometries, accretion rates, extinction properties, and hotspot structures of 67 T Tauri stars in the largest and most consistent study of ultraviolet and optical accretion signatures to date. To do so, we apply an accretion flow model to velocity-resolved H α profiles for T Tauri stars from the Hubble Space Telescope (HST) ULLYSES program with consistently derived stellar parameters. We find typical magnetospheric truncation radii to be almost half of the usually assumed value of 5 stellar radii. We then model the same stars’ HST/STIS spectra with an accretion shock model, finding a diverse range of hotspot structures. Phase-folding multiepoch shock models reveals rotational modulation of observed hotspot energy flux densities, indicative of hotspots that persist for at least three stellar rotation periods. For the first time, we perform a large-scale, self-consistent comparison of accretion rates measured using accretion flow and shock models, finding them to be consistent within ∼0.16 dex for contemporaneous observations. Finally, we find that up to 50% of the total accretion luminosity is at short wavelengths accessible only from space, highlighting the crucial role of ultraviolet spectra in constraining accretion spectral energy distributions, hotspot structure, and extinction.}, archive = {J_ApJ}, author = {Caeley V. Pittman and Catherine C. Espaillat and Connor E. Robinson and Thanawuth Thanathibodee and Sophia Lopez and Nuria Calvet and Zhaohuan Zhu and Frederick M. Walter and John Wendeborn and Carlo F. Manara and Justyn Campbell-White and Rik Claes and Min Fang and Antonio Frasca and Jorge F. Gameiro and Manuele Gangi and Jesus Hernández and Ágnes Kóspál and Karina Maucó and James Muzerolle and Michał Siwak and Łukasz Tychoniec and Laura Venuti}, doi = {10.3847/1538-4357/adef35}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {134}, shortjournal = {The Astrophys. J.}, title = {The ODYSSEUS survey. characterizing magnetospheric geometries and hotspot structures in t tauri stars}, volume = {992}, year = {2025}, }
• (2025). Prospects of constraining equilibrium tides in low-mass binary stars. ApJ, 992(1), 133. (www)

  @article{ , abstract = {The dynamical evolution of short-period low-mass binary stars (with mass M < 1.5 M ⊙ , from formation to the late main sequence, and with orbital periods less than ∼10 days) is strongly influenced by tidal dissipation. This process drives orbital and rotational evolution that ultimately results in circularized orbits and rotational frequencies synchronized with the orbital frequency. Despite the fundamental role of tidal dissipation in binary evolution, constraining its magnitude (typically parameterized by the tidal quality factor { \mathcal Q } ) has remained discrepant by orders of magnitude in the existing literature. Recent observational constraints from time-series photometry (e.g., Kepler, K2, TESS), as well as advances in theoretical models to incorporate a more realistic gravitational response within stellar interiors, are invigorating new optimism for resolving this long-standing problem. To investigate the prospects and limitations of constraining tidal { \mathcal Q } , we use global sensitivity analysis and simulation-based inference to examine how the initial conditions and tidal { \mathcal Q } influence the observable orbital and rotational states. Our results show that, even under the simplest and most tractable models of tides, the path toward inferring { \mathcal Q } from individual systems is severely hampered by inherent degeneracies between tidal { \mathcal Q } and the initial conditions, even when considering the strongest possible constraints (i.e., binaries with precise masses, ages, orbital periods, eccentricities, and rotation periods). Finally, as an alternative, we discuss how population synthesis approaches may be a more promising path forward for validating tidal theories.}, archive = {J_ApJ}, author = {Jessica Birky and Rory Barnes and James R. A. Davenport}, doi = {10.3847/1538-4357/adf4cf}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {133}, shortjournal = {The Astrophys. J.}, title = {Prospects of constraining equilibrium tides in low-mass binary stars}, volume = {992}, year = {2025}, }
• (2025). Magnetic fields in the eos cloud: Dynamically important fields in the interface between atomic and molecular gas. ApJ, 992(1), 132. (www)

  @article{ , abstract = {The recently discovered Eos molecular cloud is a CO-dark, low-density cloud located at a distance of approximately 94 pc from the Sun which does not appear to have formed stars at any point in its history. In this paper, we investigate the magnetic fields in the Eos cloud, near the interface between the atomic cold neutral medium (CNM) and molecular gas, using dust emission and extinction polarimetry. A histogram of relative orientation analysis shows that the magnetic field is preferentially parallel to the density structure of the cloud, while a Davis–Chandrasekhar–Fermi analysis finds magnetic field strengths of 6 ± 3 μ G across the Eos cloud and 12 ± 4 μ G in the somewhat denser MBM 40 subregion. These results are consistent with a previous estimate of magnetic field strength in the Local Bubble and suggest that the fields in the Eos cloud are dynamically important compared to both gravity and turbulence. Our findings are fully consistent with the expected behavior of magnetized, non-self-gravitating gas near the CNM/molecular cloud boundary.}, archive = {J_ApJ}, author = {Janik Karoly and Kate Pattle and Blakesley Burkhart and Thavisha E. Dharmawardena and B-G Andersson and Thomas J. Haworth}, doi = {10.3847/1538-4357/adf731}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {132}, shortjournal = {The Astrophys. J.}, title = {Magnetic fields in the eos cloud: Dynamically important fields in the interface between atomic and molecular gas}, volume = {992}, year = {2025}, }
• (2025). Paired: A statistical framework for detecting stellar binarity with gaia RVs. i. sensitivity to unresolved binaries. ApJ, 992(1), 131. (www)

  @article{ , abstract = {Data Release 3 (DR3) from the Gaia Mission includes radial velocity measurements of over 33 million targets. Among many scientific applications, the overlap of this stellar sample with targeted exoplanet transit survey stars presents an opportunity to understand planet occurrence in the context of stellar multiplicity on a large scale. Yet, any interpretation of occurrence relies upon an understanding of survey sensitivity. While the sensitivity to planets in transit surveys is well-understood, a characterization of the sensitivity of Gaia to unresolved binaries is also critical. We describe here a statistical framework called paired , which we developed to enable the forward modeling of Gaia radial velocity observables for large samples of stars. The paired machinery links the reported radial velocity noise for a given star from Gaia to the probability of a spatially unresolved stellar companion. We demonstrate how this enables the user, given an observed distribution of individual binary “probabilities” for a set of stars, to understand this distribution within the sensitivity limits of Gaia. For the subset of stars with the highest probability of excess radial velocity noise, we describe the ability of paired to constrain the semi-amplitude of the stellar binary. Where possible, we benchmark our inferred radial velocity semi-amplitudes against those from ground-based radial velocity surveys, as well as the subset published by Gaia DR3 itself. We aim for paired to be a community tool for the exploration of the effects of binarity on planets at a population level, but also for any user interested in stellar populations.}, archive = {J_ApJ}, author = {Quadry Chance and Daniel Foreman-Mackey and Sarah Ballard and Andrew R. Casey and Trevor J. David and Adrian M. Price-Whelan}, doi = {10.3847/1538-4357/adfb68}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {131}, shortjournal = {The Astrophys. J.}, title = {Paired: A statistical framework for detecting stellar binarity with gaia RVs. i. sensitivity to unresolved binaries}, volume = {992}, year = {2025}, }
• (2025). Examining active galactic nucleus UV/Optical variability beyond the simple damped random walk. II. insights from 22 yr observations of SDSS, PS1, and ZTF. ApJ, 992(1), 130. (www)

  @article{ , abstract = {A damped random walk (DRW) process is often used to describe the temporal UV/optical continuum variability of active galactic nuclei (AGN). However, recent investigations have shown that this model fails to capture the full spectrum of AGN variability. In this work, we model the 22 yr long light curves of 21,767 quasars, spanning the redshift range 0.28 < z < 2.71, as a noise-driven damped harmonic oscillator (DHO) process. The light curves, in the optical g and r bands, are collected and combined from the Sloan Digital Sky Survey, the Panoramic Survey Telescope and Rapid Response System, and the Zwicky Transient Facility. A DHO process can be defined using four parameters, two for describing its long-term behavior/variability, and the other two for describing its short-term behavior/variability. We find that the best-fit DHO model describes the observed variability of our quasar light curves better than the best-fit DRW model. Furthermore, the best-fit DHO parameters exhibit correlations with the rest-frame wavelength, the Eddington ratio, and the black hole mass of our quasars. Based on the power spectral density shape of the best-fit DHOs and these correlations, we suggest that the observed long-term variability of our quasars can be best explained by accretion rate or thermal fluctuations originating from the accretion disk, and the observed short-term variability can be best explained by reprocessing of X-ray variability originating from the corona. The additional information revealed by DHO modeling emphasizes the need to go beyond DRW when analyzing AGN light curves delivered by next-generation wide-field time-domain surveys.}, archive = {J_ApJ}, author = {Weixiang Yu and Gordon T. Richards and John J. Ruan and Michael S. Vogeley and Franz E. Bauer and Matthew J. Graham}, doi = {10.3847/1538-4357/adfdd2}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {130}, shortjournal = {The Astrophys. J.}, title = {Examining active galactic nucleus UV/Optical variability beyond the simple damped random walk. II. insights from 22 yr observations of SDSS, PS1, and ZTF}, volume = {992}, year = {2025}, }
• (2025). Joint analysis of h i absorption zeeman measurements and the morphology of filamentary h i emission. ApJ, 992(1), 129. (www)

  @article{ , abstract = {We present a joint analysis of H I absorption Zeeman measurements and the morphology of filamentary H I emission to investigate the 3D structure of the magnetic field in the diffuse neutral interstellar medium. Our analysis is based on the Arecibo Millennium Survey and new data from the Five-hundred-meter Aperture Spherical radio Telescope toward radio sources 3C 75, 3C 207, and 3C 409. Toward 3C 409, we make a 4 σ Zeeman detection and infer B LOS = 9.1 ± 1.9 μ G, in agreement with Arecibo results. We quantify the dispersion of H I filaments at the locations and velocities of Zeeman components using GALFA-H I narrow-channel emission maps. Focusing on a subsample of 42 spectrally distinct components, we find a weak but statistically significant positive correlation (Spearman ρ = 0.3, p = 0.01) between ∣ B LOS ∣ and the circular variance of H I filament orientation angles. To examine its origin, we characterize the environments probed by H I absorption using dust emission, 3D dust maps, OH absorption, and CO emission. We find evidence that existing H I absorption Zeeman measurements trace magnetic fields that are coherent on parsec scales, probe primarily local gas (100–500 pc, often at distances consistent with the Local Bubble wall), and exhibit systematic differences in the magnitude of B LOS . We attribute the correlation between Zeeman measurements and filamentary H I morphology to large-scale variations in magnetic field strength and/or inclination angle across different Galactic environments, which could arise due to the Local Bubble geometry or enhanced total field strength in denser regions.}, archive = {J_ApJ}, author = {Marta Nowotka and Susan E. Clark and Blakesley Burkhart and Laura Fissel and Tao-Chung Ching and Timothy Robishaw and Carl Heiles}, doi = {10.3847/1538-4357/adff52}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {129}, shortjournal = {The Astrophys. J.}, title = {Joint analysis of h i absorption zeeman measurements and the morphology of filamentary h i emission}, volume = {992}, year = {2025}, }
• (2025). Probing the turbulent corona and heliosphere using radio spectral imaging observation during the solar conjunction of the crab nebula. ApJ, 992(1), 128. (www)

  @article{ , abstract = {Measuring plasma parameters in the upper solar corona and inner heliosphere is challenging because of the region’s weakly emissive nature and inaccessibility for most in situ observations. Radio imaging of broadened and distorted background astronomical radio sources during solar conjunction can provide unique constraints for the coronal material along the line of sight. In this study, we present radio spectral imaging observations of the Crab Nebula (Tau A) from 2024 June 9 to June 22 when it was near the Sun with a projected heliocentric distance of 5–27 solar radii, using the Owens Valley Radio Observatory’s Long Wavelength Array at multiple frequencies in the 30–80 MHz range. The imaging data reveal frequency-dependent broadening and distortion effects caused by anisotropic wave propagation through the turbulent solar corona at different distances. We analyze the brightness, size, and anisotropy of the broadened images. Our results provide detailed observations showing that the eccentricity of the unresolved source increases as the line of sight approaches the Sun, suggesting a higher anisotropic ratio of the plasma turbulence closer to the Sun. In addition, the major axis of the elongated source is consistently oriented in the direction perpendicular to the radial direction, suggesting that the turbulence-induced scattering effect is more pronounced in the direction transverse to the coronal magnetic field. Lastly, when the source undergoes large-scale refraction as the line of sight passes through a streamer, the apparent source exhibits substructures at lower frequencies. This study demonstrates that observations of celestial radio sources with lines of sight near the Sun provide a promising method for measuring turbulence parameters in the inner heliosphere.}, archive = {J_ApJ}, author = {Peijin Zhang and Surajit Mondal and Bin Chen and Sijie Yu and Dale Gary and Marin M. Anderson and Judd D. Bowman and Ruby Byrne and Morgan Catha and Xingyao Chen and Sherry Chhabra and Larry D’Addario and Ivey Davis and Jayce Dowell and Katherine Elder and Gregg Hallinan and Charlie Harnach and Greg Hellbourg and Jack Hickish and Rick Hobbs and David Hodge and Mark Hodges and Yuping Huang and Andrea Isella and Daniel C. Jacobs and Ghislain Kemby and John T. Klinefelter and Matthew Kolopanis and Nikita Kosogorov and James Lamb and Casey J. Law and Nivedita Mahesh and Brian O’Donnell and Kathryn Plant and Corey Posner and Travis Powell and Vinand Prayag and Andres Rizo and Andrew Romero-Wolf and Jun Shi and Greg Taylor and Jordan Trim and Mike Virgin and Akshatha Vydula and Sandy Weinreb and David Woody}, doi = {10.3847/1538-4357/adff56}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {128}, shortjournal = {The Astrophys. J.}, title = {Probing the turbulent corona and heliosphere using radio spectral imaging observation during the solar conjunction of the crab nebula}, volume = {992}, year = {2025}, }
• (2025). Testing the young fast radio burst progenitor hypothesis: A crossmatch of catalog-1 CHIME bursts with historic local universe supernovae. ApJ, 992(1), 127. (www)

  @article{ , abstract = {Fast radio bursts (FRBs) are among the most energetic and enigmatic transients in the radio sky, with mounting evidence suggesting newborn, highly magnetized neutron stars formed in core-collapse supernovae (CCSNe) as their sources. A definitive spatial association between an FRB and a historic CCSN would confirm this link and tightly constrain young neutron-star source models. Here we report on the first systematic crossmatching of 886 spectroscopically classified CCSNe in the local Universe ( z ≤ 0.043) against 241 CHIME/FRB Catalog 1 events, applying rigorous spatial, dispersion measure (DM), and scattering time ( τ ) criteria. We identify four positional overlaps, all consistent with a chance alignment; however, one pair, FRB 20190412B–SN 2009gi, also satisfies independent host-DM and τ constraints, making it a promising candidate for targeted follow-up. Next, we search for compact (persistent or transient) radio emission at all matched supernova sites using multiepoch Very Large Array Sky Survey data and detect none. Treating every CCSN sight line as a nondetection, we derive Poisson upper limits on the FRB burst rate at these locations, which lie well below the rates observed for the most active repeaters unless their activity is heavily suppressed by beaming, intermittency, or residual free–free absorption. We then develop a galaxy-integrated FRB-rate model that incorporates an intrinsic spectral index, secular magnetar-activity decay, and frequency-dependent free–free opacity. Applying this formalism to existing FRB data shows that reproducing the observed CHIME/CRAFT all-sky rate ratio requires a steep decline in magnetar burst rate with age. Finally, our work underscores the necessity of subarcsecond localizations and multiwavelength follow-up to definitively test the young neutron star source hypothesis.}, archive = {J_ApJ}, author = {Wanqing Liu and Mohit Bhardwaj and Ben Margalit}, doi = {10.3847/1538-4357/adff5c}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {127}, shortjournal = {The Astrophys. J.}, title = {Testing the young fast radio burst progenitor hypothesis: A crossmatch of catalog-1 CHIME bursts with historic local universe supernovae}, volume = {992}, year = {2025}, }
• (2025). Exploration of the outer envelope of the K-giant star beta cet*. ApJ, 992(1), 126. (www)

  @article{ , abstract = {Investigating the atmospheres of giants and supergiants is critical to expanding our knowledge of stellar life cycles, galaxy formation, and the origin of material that forms exoplanets. This paper presents the analysis of the evolved K-type giant β Cet using high-quality spectral data collected by the Hubble Space Telescope/Space Telescope Imaging Spectrograph (STIS), including an ultraviolet atlas with line identifications that will support future studies of cool, evolved stars. Beta Cet exhibits chromosphere emission, transition region diagnostics, and coronal X-ray flux, placing it near the Linsky–Haisch dividing line that separates objects with strong coronal signatures from the cooler giants and supergiants with massive stellar winds. The transition region in β Cet produces clear features in the STIS spectra that are formed at {\mathrm{log}}\,T\lt 5.40 K, in addition to the highly ionized Fe xxi λ 1354. It is stronger and more dominant than observed in the K5III hybrid star γ Dra, with a line surface flux as much as 2–3 orders of magnitude greater. The majority of the transition region lines are significantly broader than expected from thermal motion alone, and this nonthermal broadening appears to increase with formation temperature. The nonthermal width of the C iv and Si iv doublets is used to investigate the dominant heating mechanisms in β Cet’s transition region. We find that the radiative losses observed in the ultraviolet are balanced by an energy influx from sound waves and turbulence, while the Alfvén waves supported by a magnetic field are required to account for the reported X-ray flux.}, archive = {J_ApJ}, author = {Krister E. Nielsen and Gioia Rau and Kenneth G. Carpenter}, doi = {10.3847/1538-4357/adff5d}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {126}, shortjournal = {The Astrophys. J.}, title = {Exploration of the outer envelope of the K-giant star beta cet*}, volume = {992}, year = {2025}, }
• (2025). Surface composition of asteroid 269 justitia: Insights from spectral mixture modeling. ApJ, 992(1), 125. (www)

  @article{ , abstract = {Asteroid (269) Justitia is one of the more unusual asteroids in the main belt due to its extremely red spectral slope at visible and near infrared (VNIR) wavelengths. While the surface composition of (269) Justitia remains uncertain due to a lack of diagnostic absorption features in the VNIR region, intriguing clues to its nature are provided by recent mid- and thermal-infrared wavelength observations (MIR and TIR, respectively). In the VNIR, no identifiable analogs to Justitia can be found among the known meteorites. Instead, the best spectral matches come from Trans-Neptunian Objects (TNOs), possibly suggesting a genetic relationship with those bodies. On the other hand, recent TIR emissivity spectra reveal the likely presence of fine-grained anhydrous silicates on Justitia’s surface, possibly inconsistent with a TNO origin. To explore this issue, we used a radiative transfer mixing model to investigate the spectral nature of Justitia in the VNIR and TIR. In the VNIR, our results are consistent with mixtures of space weathered silicates and carbonaceous material, though the presence of complex organics cannot be ruled out. In the TIR, our results favor either carbonaceous material or a mixture of space-weathered silicates and carbonaceous components. The best spectral match to Justitia’s spectra was found by blending carbonaceous material with moderate to extensively space-weathered silicates. This combination could, in turn, indicate a potential collision between silicate-rich and carbonaceous bodies during the early history of Justitia.}, archive = {J_ApJ}, author = {Harish and P. O. Hayne and J. P. Emery and W. F. Bottke and Christopher S. Edwards and M. R. El-Maarry and H. AlMazmi and the EMA Science and Space Resources Team}, doi = {10.3847/1538-4357/adff70}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {125}, shortjournal = {The Astrophys. J.}, title = {Surface composition of asteroid 269 justitia: Insights from spectral mixture modeling}, volume = {992}, year = {2025}, }
• (2025). High-sensitivity molecular line observations toward the l1544 prestellar core challenge current models*. ApJ, 992(1), 124. (www)

  @article{ , abstract = {The increased sensitivity and spectral resolution of observed spectra toward the prestellar core L1544 are challenging the current physical and chemical models. With the aim of further constraining the structure of L1544 as well as assessing the completeness of chemical networks, we turn to radiative transfer modeling of observed molecular lines toward this source. We obtained high-sensitivity and high spectral resolution observations of HCO + ( J = 1–0), CS ( J = 2–1), C 34 S ( J = 2–1), H 2 CO ( J {}_{{K}_{a},{K}_{c}} = 2 1,2 –1 1,1 ), c-C 3 H 2 ( J {}_{{K}_{a},{K}_{c}} = 2 1,2 –1 0,1 ), SO ( N , J = 2, 3–1, 2), and 34 SO ( N , J = 2, 3–1, 2) with the IRAM 30 m telescope toward the dust peak of L1544. A non–local thermodynamic equilibrium radiative transfer code is coupled to the Markov Chain Monte Carlo method to model the observations. We find that with just one transition for each isotope, the modeling cannot find a global minimum that fits the observations. The derived fractional abundance profiles are compared to those computed with chemical models. The observed transitions trace gas components with distinct dynamics at different distances along the radius of the core. Moreover, the results evidence a poor reproduction of sulfur chemistry by chemical modeling and stress the need to include a more consistent S-depletion process to accurately reproduce the S-chemistry toward dense cores.}, archive = {J_ApJ}, author = {J. Ferrer Asensio and S. S. Jensen and S. Spezzano and P. Caselli and F. O. Alves and O. Sipilä and E. Redaelli}, doi = {10.3847/1538-4357/adff78}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {124}, shortjournal = {The Astrophys. J.}, title = {High-sensitivity molecular line observations toward the l1544 prestellar core challenge current models*}, volume = {992}, year = {2025}, }
• (2025). Radio variability in recently quenched galaxies: The impact of tidal disruption event or active galactic nucleus-driven outflows. ApJ, 992(1), 123. (www)

  @article{ , abstract = {Outflows and jets launched from the nuclei of galaxies emit radio synchrotron emission that can be used to study the impact of accretion energy on the host galaxy. The decades-long baseline now enabled by large radio surveys allows us to identify cases where new outflows or jets have been launched. Here, we present the results of a targeted Very Large Array program observing four poststarburst galaxies that have brightened significantly in radio emission over the past ∼20 yr. We obtain quasi-simultaneous observations in five bands (1–18 GHz) for each source. We find peaked spectral energy distributions, indicative of self-absorbed synchrotron emission. While all four sources have risen significantly over the past ∼20 yr in the 1–2 GHz band, two also show clear recent flares in the 2–4 GHz band. These sources are less luminous than typical peaked-spectrum radio active galactic nucleus (AGN). It remains unclear whether these sources are low luminosity analogs of the peaked radio AGN from accreted gas, or driven by tidal disruption events with missed optical flares. Regardless of the source of the accreted material, these newly launched outflows contain sufficient energy to drive the molecular gas outflows observed in poststarburst galaxies and to drive turbulence, suppressing star formation.}, archive = {J_ApJ}, author = {K. Decker French and Kristina Nyland and Pallavi Patil and Kishalay De and Dillon Dong and Nicholas Earl and Samaresh Mondal and Kate Rowlands and Margaret Shepherd and Margaret E. Verrico}, doi = {10.3847/1538-4357/adff7a}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {123}, shortjournal = {The Astrophys. J.}, title = {Radio variability in recently quenched galaxies: The impact of tidal disruption event or active galactic nucleus-driven outflows}, volume = {992}, year = {2025}, }
• (2025). A detection of helium in the bright superluminous supernova SN 2024rmj. ApJ, 992(1), 122. (www)

  @article{ , abstract = {We present extensive ultraviolet, optical, and near-infrared (NIR) photometric and spectroscopic observations of the nearby hydrogen-poor superluminous supernova (SLSN-I) SN 2024rmj at z = 0.1189. SN 2024rmj reached a peak absolute magnitude of M g ≈ −21.9, placing it at the luminous end of the SLSN-I distribution. The light curve exhibits a pronounced prepeak bump (≈60 days before the main peak) and a postpeak bump (≈55 days after the main peak). The bulk of the light curve is otherwise well fit by a magnetar spin-down model, with typical values (spin: ≈2.1 ms; magnetic field: ≈6 × 10 13 G; ejecta mass: ≈12 M ⊙ ). The optical spectra exhibit characteristic SLSN-I features and evolution, but with a relatively high velocity of ≈8000 km s −1 postpeak. Most significantly, we find a clear detection of helium in the NIR spectra at He i λ 1.083 μ m and λ 2.058 μ m, blueshifted by ≈15,000 km s −1 (13 days before peak) and ≈13,000 km s −1 (40 days after peak), indicating that helium is confined to the outermost ejecta; based on these NIR detections, we also identify likely contribution from He i λ 5876 in the optical spectra on a similar range of timescales. This represents the most definitive detection of helium in a bright SLSN-I to date, and indicates that progenitors with a thin helium layer can still explode as SLSNe.}, archive = {J_ApJ}, author = {Harsh Kumar and Edo Berger and Peter K. Blanchard and Daichi Hiramatsu and Sebastian Gomez and Alex Gagliano and Moira Andrews and K. Azalee Bostroem and Joseph Farah and D. Andrew Howell and Curtis McCully}, doi = {10.3847/1538-4357/adff7e}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {122}, shortjournal = {The Astrophys. J.}, title = {A detection of helium in the bright superluminous supernova SN 2024rmj}, volume = {992}, year = {2025}, }
• (2025). DESI emission-line galaxies: Clustering dependence on stellar mass and [O II] luminosity. ApJ, 992(1), 121. (www)

  @article{ , abstract = {We measure the projected two-point correlation functions of emission-line galaxies (ELGs) from the Dark Energy Spectroscopic Instrument One-Percent Survey and model their dependence on stellar mass and [O II ] luminosity. We select ∼180,000 ELGs with redshifts of 0.8 < z < 1.6, and define 27 samples according to cuts in redshift and both galaxy properties. Following a framework that describes the conditional [O II ] luminosity–stellar mass distribution as a function of halo mass, we simultaneously model the clustering measurements of all samples at fixed redshift. Based on the modeling result, most ELGs in our samples are classified as central galaxies, residing in halos of a narrow mass range with a typical median of ∼10 12.2−12.4 h −1 M ⊙ . We observe a weak dependence of clustering amplitude on stellar mass, which is reflected in the model constraints and is likely a consequence of the 0.5 dex measurement uncertainty in the stellar mass estimates. The model shows a trend between galaxy bias and [O II ] luminosity at high redshift (1.2 < z < 1.6) that is otherwise absent at lower redshifts.}, archive = {J_ApJ}, author = {T. Hagen and K. S. Dawson and Z. Zheng and J. Aguilar and S. Ahlen and S. BenZvi and D. Bianchi and D. Brooks and F. J. Castander and T. Claybaugh and A. Cuceu and A. de la Macorra and P. Doel and S. Ferraro and A. Font-Ribera and J. E. Forero-Romero and E. Gaztañaga and S. Gontcho A Gontcho and V. Gonzalez-Perez and G. Gutierrez and C. Hahn and K. Honscheid and M. Ishak and S. Juneau and R. Kehoe and T. Kisner and A. Kremin and C. Lamman and M. Landriau and L. Le Guillou and A. Leauthaud and M. E. Levi and M. Manera and A. Meisner and R. Miquel and J. Moustakas and S. Nadathur and N. Palanque-Delabrouille and F. Prada and I. Pérez-Ràfols and A. J. Ross and G. Rossi and S. Saito and E. Sanchez and D. Schlegel and M. Schubnell and J. Silber and D. Sprayberry and G. Tarlé and B. A. Weaver and R. Zhou and H. Zou}, doi = {10.3847/1538-4357/ae0036}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {121}, shortjournal = {The Astrophys. J.}, title = {DESI emission-line galaxies: Clustering dependence on stellar mass and [O II] luminosity}, volume = {992}, year = {2025}, }
• (2025). Prospects for EMRI/MBH parameter estimation using quasiperiodic eruption timings: Short-timescale analysis. ApJ, 992(1), 120. (www)

  @article{ , abstract = {Quasiperiodic eruptions (QPEs) are luminous, recurring X-ray outbursts from galactic nuclei, with timescales of hours to days. While their origin remains uncertain, leading models invoke accretion disk instabilities or the interaction of a massive black hole (MBH) with a lower-mass secondary in an extreme mass ratio inspiral (EMRI). EMRI scenarios offer a robust framework for interpreting QPEs by characterizing observational signatures associated with the secondary’s orbital dynamics. This, in turn, enables extraction of the MBH/EMRI physical properties and provides a means to test the EMRI scenario, distinguishing models and addressing the question: what can QPE timings teach us about MBHs and EMRIs? In this study, we employ analytic expressions for Kerr geodesics to efficiently resolve the trajectory of the secondary object and perform GPU-accelerated Bayesian inference to assess the information content of QPE timings. Using our inference framework, referred to as QPE-FIT (Fast Inference with Timing; https://github.com/joheenc/QPE-FIT/tree/main ), we explore QPE timing constraints on astrophysical parameters, such as EMRI orbital parameters and MBH mass/spin. We find that mild-eccentricity EMRIs ( e ∼ 0.1–0.3) can constrain MBH mass and EMRI semimajor axis/eccentricity to the 10% level within tens of orbital periods, while MBH spin is unconstrained for the explored semimajor axes ≥100 R g and monitoring baselines { \mathcal O } (10–100) orbits. Introducing a misaligned precessing disk generally degrades inference of EMRI orbital parameters, but can constrain disk precession properties within 10%–50%. This work both highlights the prospect of QPE observations as dynamical probes of galactic nuclei and outlines the challenge of doing so in the multimodal parameter space of EMRI–disk collisions.}, archive = {J_ApJ}, author = {Joheen Chakraborty and Lisa V. Drummond and Matteo Bonetti and Alessia Franchini and Shubham Kejriwal and Giovanni Miniutti and Riccardo Arcodia and Scott A. Hughes and Francisco Duque and Erin Kara and Alberto Sesana and Margherita Giustini and Amedeo Motta and Kevin Burdge}, doi = {10.3847/1538-4357/ae003b}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {120}, shortjournal = {The Astrophys. J.}, title = {Prospects for EMRI/MBH parameter estimation using quasiperiodic eruption timings: Short-timescale analysis}, volume = {992}, year = {2025}, }
• (2025). Spectral properties of globally distributed ENA fluxes across diverse regions of the heliosphere. ApJ, 992(1), 119. (www)

  @article{ , abstract = {This study analyzes energetic neutral atom (ENA) spectral properties across distinct regions of globally distributed flux (GDF) sky maps, using Interstellar Boundary Explorer data from a full solar cycle, corrected for time dispersion. By time-shifting the data to the heliosheath using GDF source distances from D. B. Reisenfeld et al., we achieve a more accurate representation of heliosheath GDF energy spectra. We quantify ENA spectral characteristics, heliosheath line-of-sight-integrated proton pressure, and heliosheath proton temperature, comparing these to solar wind properties at 1 au and interplanetary scintillation-derived solar wind data. Our findings show that the spectral index is generally anticorrelated with heliosheath proton temperature and pressure, except in the central tail, where a partial positive correlation is observed. The lowest spectral index values occur when high-latitude heliosheath regions are dominated by fast solar wind from polar coronal holes. The south pole exhibits the flattest energy spectra due to plasma heating from both fast solar wind and a late-2014 pressure pulse. The central tail shows shorter variability (5–6 yr) for spectral index and heliosheath proton temperature, while proton pressure follows the 11 yr solar cycle. Most spectral shapes exhibit a “knee” distribution, peaking during solar maximum, with an “ankle” shape observed only at the south pole during solar cycle transitions. Asymmetry in proton pressure in the lobes is driven by the draping effect of the local interstellar magnetic field. This study provides insights into the energetic properties of GDF across the heliosphere, enhancing our understanding of the heliospheric environment.}, archive = {J_ApJ}, author = {Thomas K. Kim and Daniel B. Reisenfeld and Eric J. Zirnstein and Paul H. Janzen and Asher S. Merrill and Sung Jun Noh and Nehpreet K. Walia and Yue Chen and Fan Guo and Dave Osthus and Lauren J. Beesley and Dae-Kyu Shin and Justyna M. Sokół and Maciej Bzowski and Marzena A. Kubiak and Czeslaw Porowski and Herbert O. Funsten}, doi = {10.3847/1538-4357/ae0183}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {119}, shortjournal = {The Astrophys. J.}, title = {Spectral properties of globally distributed ENA fluxes across diverse regions of the heliosphere}, volume = {992}, year = {2025}, }
• (2025). The global structure of the heliosphere. ApJ, 992(1), 118. (www)

  @article{ , abstract = {As the Sun moves through the local interstellar medium (LISM), it emits charged particles, creating the heliosphere occupied by the plasma of solar origin. Determining the structure of the heliosphere is a fundamental question that can be answered only by numerical simulations based on sophisticated theoretical models. Apart from the physics involved in the interaction of fully ionized, collisionless solar wind (SW) with the partially ionized, weakly collisional LISM, it is natural for humankind to speculate about our place of habitat as seen from a distance. This is especially germane now in light of recently observed astrospheres that possess substantially different shapes and structures. We present simulations of the SW–LISM interaction in a very large computational box, paying specific attention to modifications of the LISM properties caused by the presence of the heliosphere. Our results show that the heliosphere has a long heliotail, whose morphology is affected by the interstellar magnetic field pressure, so it acquires a sheetlike shape oriented along the plane formed by the interstellar magnetic field and velocity vectors in the unperturbed LISM. The SW–LISM boundary is subject to instabilities. A possibility is demonstrated of a quasi-parallel, slow-mode bow shock that affects some parts of the LISM flow. We demonstrate that the complex heliospheric structure affects the distribution of plasma and magnetic field in the LISM, resulting in a Galactic cosmic ray anisotropy consistent with the Tibet air shower experiment. We also analyze the effect of turbulence on the length of the heliotail and its ultimate destruction.}, archive = {J_ApJ}, author = {Nikolai V. Pogorelov and Federico Fraternale and Gary P. Zank and Ming Zhang}, doi = {10.3847/1538-4357/ae0193}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {118}, shortjournal = {The Astrophys. J.}, title = {The global structure of the heliosphere}, volume = {992}, year = {2025}, }
• (2025). Investigating little red dots with UV excess: Are they the high-redshift siblings of blue hot dust-obscured galaxies?. ApJ, 992(1), 117. (www)

  @article{ , abstract = {Little red dots (LRDs), newly identified compact and dusty galaxies with an unexpectedly high number density observed by JWST, have an unusual “V-shaped” rest-frame UV to near-infrared spectral energy distribution (SED). A group of hyperluminous, obscured quasars with excess blue emission, called blue-excess hot dust-obscured galaxies (BHDs), also exhibit qualitatively similar SEDs to those of LRDs. They represent a rare population of galaxies hosting supermassive black holes (SMBHs) accreting near the Eddington limit at redshifts z ∼ 1–4. In this study, we compare their multiwavelength SEDs to investigate whether LRDs, or a subset of them, could be high-redshift analogs of BHDs. Our analysis reveals that despite their similar “V-shape” SEDs, LRDs appear to be a different population than BHDs. The “V-shape” of BHDs appears at longer wavelengths compared to LRDs due to different selection strategies, suggesting LRDs have much less dust attenuation than typical BHDs. The bluer colors in the rest-frame infrared (continuum) emission of LRDs suggest the absence of hot dust heated by active galactic nuclei (AGN) accretion activities. We also argue that the blue excess in LRDs is unlikely from AGN scattered light. The compact morphologies and lower X-ray detection frequencies of LRDs suggest a distinct formation pathway from BHDs, which are thought to be powered by super-Eddington accretion onto central SMBHs following major galaxy mergers.}, archive = {J_ApJ}, author = {Lulu Bao and Chao-Wei Tsai and Jingwen Wu and Tao Wang and Guodong Li and Roberto J. Assef and Tanio Diaz-Santos and Peter R. M. Eisenhardt and Daniel Stern and Andrew W. Blain}, doi = {10.3847/1538-4357/ae019e}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {117}, shortjournal = {The Astrophys. J.}, title = {Investigating little red dots with UV excess: Are they the high-redshift siblings of blue hot dust-obscured galaxies?}, volume = {992}, year = {2025}, }
• (2025). Irradiated pulsar planets and companions as 511 keV positron annihilation line sources. ApJ, 992(1), 116. (www)

  @article{ , abstract = {Millisecond pulsars (MSPs) are prolific GeV γ -ray emitters, and nearly 80% of Fermi Large Area Telescope MSPs reside in compact binaries. For the first time in the literature, we demonstrate that the companions in these compact MSPs binaries are also 511 keV annihilation line emitters using MEGAlib simulations (a high-energy radiation transport software built with Geant4 ) to compute the particle showers and resulting backsplash emission from the pulsar irradiation. The 511 keV signal exhibits strong flux modulation and red- and blueshifts associated with a binary orbit, enabling powerful coherent searches. Measuring the 511 keV emission would enable direct γ -ray characterization of unusual pulsar exoplanets and companions, and allow one to identify the unambiguous presence of active pulsars whose beams do not intercept Earth. Intriguingly, the 511 keV flux is brightest for ultracompact systems, against which pulsar surveys are systematically biased. These ultracompact systems are also possibly prime Laser Interferometer Space Antenna (LISA) Galactic sources. This necessitates future joint LISA–MeV γ -ray techniques to characterize MSP binaries. These MSP binaries may also contribute to the puzzling source of the excess 511 keV photons near the Galactic bulge and center.}, archive = {J_ApJ}, author = {Zachary Metzler and Zorawar Wadiasingh}, doi = {10.3847/1538-4357/ae031f}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {116}, shortjournal = {The Astrophys. J.}, title = {Irradiated pulsar planets and companions as 511 keV positron annihilation line sources}, volume = {992}, year = {2025}, }
• (2025). Can the anomalous magnetic braking of Ap/Bp stars explain the orbital decay of algol-type binaries?. ApJ, 992(1), 115. (www)

  @article{ , abstract = {Several Algol-type binaries were detected to be experiencing rapid orbital decay, which is in contradiction with the conservative mass transfer model. In this work, we investigate whether anomalous magnetic braking (MB) of intermediate-mass Ap/Bp stars, characterized by surface magnetic fields of ∼10 2 –10 4 G, could drive orbital decay through magnetic wind–field coupling. Using the stellar evolution code MESA , we simulate the evolution of several main-sequence binaries containing Ap/Bp stars, with typical initial parameters of Algol binaries. Our models indicate that the anomalous MB mechanism could induce orbital decay in long timescales (hundreds of Myr to several Gyr), reproducing several basic Algol parameters such as the effective temperatures and luminosities of donor stars. However, the predicted orbital period decay rates are much lower than those observed in several Algol systems. We analyze the limitations of the anomalous MB model and discuss alternative mechanisms that could account for the long- or short-term orbital period variations observed in Algol systems, including a surrounding circumbinary disk, stellar expansion, the Applegate mechanism, and the light-travel-time effect. Long-term observations are still required to distinguish between these mechanisms in the future.}, archive = {J_ApJ}, author = {Guan-Long Wu and Zhao-Yu Zuo and Wen-Cong Chen}, doi = {10.3847/1538-4357/ae0331}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {115}, shortjournal = {The Astrophys. J.}, title = {Can the anomalous magnetic braking of Ap/Bp stars explain the orbital decay of algol-type binaries?}, volume = {992}, year = {2025}, }
• (2025). A time-dependent solution for GSN 069 disk evolution and the nature of long-lived tidal disruption events. ApJ, 992(1), 114. (www)

  @article{ , abstract = {We present the implementation of a fully time-dependent relativistic disk model—based on the light-curve fitting package FitTeD —into the X-ray spectral fitting environment, pyXspec . This implementation enables simultaneous fitting of multi-epoch and multiwavelength spectral data, where the only free parameters are those describing the black hole and the initial conditions, while the subsequent evolution is governed by the dynamical equations of an evolving accretion flow. We use it to fit seven epochs of X-ray spectra and two epochs of UV spectra of the “long-lived” tidal disruption event (TDE) and quasiperiodic eruption (QPE) source GSN 069, from 2010 through late-2019. Our results show that such “long-lived,” X-ray-bright TDEs—of which GSN 069 is a prime, but not unique, example—can naturally be explained within the same framework as events with shorter-lived X-ray emission, like ASASSN-14li and AT2019dsg. Their distinction lies in the “viscous” timescale parameter—tied to the disk’s angular momentum transport efficiency—which should be treated as a free parameter when modeling the disk evolution of transient events. We examine the implications for QPE models by tracking the time evolution of disk properties such as mass surface density and accretion rate. We argue that existing QPE models may not be able to reproduce the observed connection between the presence (2018) or absence (2014) of eruptions and the disk properties. In the context of orbiter–disk collision models, the change in mass surface density appears insufficient to explain the needed variation in the eruption’s temperature. The absence of eruptions in GSN 069 in 2014 remains a challenge for QPE models.}, archive = {J_ApJ}, author = {M. Guolo and A. Mummery and A. Ingram and M. Nicholl and S. Gezari and E. Nathan}, doi = {10.3847/1538-4357/ae039e}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {114}, shortjournal = {The Astrophys. J.}, title = {A time-dependent solution for GSN 069 disk evolution and the nature of long-lived tidal disruption events}, volume = {992}, year = {2025}, }
• (2025). Investigation of interstellar scintillation of the millisecond pulsar b1937+21 with the FAST. ApJ, 992(1), 113. (www)

  @article{ , abstract = {Pulsar scintillation serves as a valuable tool for investigating interstellar scattering screens and their properties. In this paper, we report on multiepoch interstellar scintillation from the millisecond pulsar B1937+21 (J1939+2134) using Five-hundred-meter Aperture Spherical radio Telescope (FAST) observations at 1250 MHz with 500 MHz bandwidth. The diffractive scintillation properties are investigated for an observing baseline of 3 yr. The scintillation timescale, exponential index, and decorrelation bandwidth are determined to be 7.67  ±  1.61 minutes, 1.54  ±  0.09, and 0.56  ±  0.25 MHz, respectively, from the autocorrelation functions of the dynamic spectra. These scintillation parameters are found to vary temporally. The frequency dependencies of scintillation parameters exhibit single-power spectral behaviors; however, the derived spectral indices deviate from the theoretical Kolmogorov spectrum. The fringe pattern that forms from interference of scattered waves is revealed in the secondary spectrum as a parabolic arc with a well-determined curvature of 0.95  ±  0.50 s 3 . The parabolic arc is present contemporaneously over a wide frequency range and scales with frequency as a power law with an index of −0.80 ± 0.18, indicating the broadband nature of the scintillation arc. The arc curvature exhibits annual variation and is well approximated by a one-dimensional scattering screen located approximately 95% of the distance toward the pulsar. These findings will contribute to a deeper understanding of the underlying physics of the ionized interstellar medium.}, archive = {J_ApJ}, author = {Zhigang Wen and Hui Wang and Zhen Wang and Jianping Yuan and Na Wang and Wenming yan and Wei Han and Xuefeng Duan and Honguang Wang and Pengcheng He and Jianling Chen and Chengbing Lyu}, doi = {10.3847/1538-4357/ae0452}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {113}, shortjournal = {The Astrophys. J.}, title = {Investigation of interstellar scintillation of the millisecond pulsar b1937+21 with the FAST}, volume = {992}, year = {2025}, }
• (2025). Magnetic island structures associated with kinetic alfvén solitary wave in two-fluid plasma. ApJ, 992(1), 112. (www)

  @article{ , abstract = {We investigate the formation of magnetic islands and the onset of tearing instability within kinetic Alfvén solitary waves in a two-fluid space plasma. These localized structures, featuring internal magnetic shear, naturally support magnetic reconnection processes analogous to tearing modes in magnetically confined fusion plasmas. Treating the solitary wave as a quasi-static background equilibrium, we analyze the resulting topological modifications by making use of the magnetic flux function, in analogy with tokamak plasmas. We find that the spatial size of the magnetic island scales with the square root of the magnetic flux perturbation. Introducing the tearing stability index {{\rm{\Delta }}}^{{\prime} } , we derive the growth rate of the tearing mode using a resistive magnetohydrodynamic framework. Our analysis reveals that tearing modes grow only when the mode’s wavenumber exceeds the inhomogeneity scale, becoming marginally stable when the two are comparable. The emergence of magnetic islands has significant implications for cross-field particle transport, turbulence, and acceleration. In particular, the electron diffusion across magnetic fields may be governed by the island size rather than the Larmor radius, potentially accounting for anomalous transport. Furthermore, in certain regimes, unbounded island growth may signal the collapse of the solitary wave structure, enabling a large-scale transfer of magnetic energy to particle energy. These results suggest a unifying mechanism connecting magnetic reconnection in space plasmas with tearing instabilities in laboratory fusion plasmas.}, archive = {J_ApJ}, author = {Cheong R. Choi and M.-H. Woo and Peter H. Yoon and Kwangsun Ryu and H. K. Cho and Jungjoon Seough and D.-Y. Lee}, doi = {10.3847/1538-4357/ae0716}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {112}, shortjournal = {The Astrophys. J.}, title = {Magnetic island structures associated with kinetic alfvén solitary wave in two-fluid plasma}, volume = {992}, year = {2025}, }
• (2025). General relativity can prevent a runaway greenhouse on potentially habitable planets orbiting white dwarfs. ApJ, 992(1), 111. (www)

  @article{ , abstract = {Planets orbiting in the habitable zones of white dwarfs have recently been proposed as promising targets for biosignature searches. However, since the white dwarf habitable zone resides at 0.01–0.1 au, planets residing there are subject to tidal heating if they have any orbital eccentricity. Previous work identified nearby planetary companions as potential roadblocks to habitability of planets around white dwarfs, as such companions could induce secular oscillations in eccentricity for the potentially habitable planet, which could in turn heat a surface ocean and induce a runaway greenhouse for even very low values ( e ∼ 10 −4 ) of the eccentricity of the potentially habitable planet. In this work, we examine the potential for general relativistic orbital precession to protect habitable planets orbiting white dwarfs from such a runaway greenhouse and demonstrate that, for some system architectures, general relativity can be protective for planetary habitability.}, archive = {J_ApJ}, author = {Eva Stafne and Juliette Becker}, doi = {10.3847/1538-4357/ae07c6}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {111}, shortjournal = {The Astrophys. J.}, title = {General relativity can prevent a runaway greenhouse on potentially habitable planets orbiting white dwarfs}, volume = {992}, year = {2025}, }
• (2025). Identifying the secondary jet in the RadioAstron image of OJ 287. ApJ, 992(1), 110. (www)

  @article{ , abstract = {The 136 yr long optical light curve of OJ 287 is explained by a binary black hole model where the secondary is in a 12 yr orbit around the primary. Impacts of the secondary on the accretion disk of the primary generate a series of optical flares that follow a quasi-Keplerian relativistic mathematical model. The orientation of the binary in space is determined from the behavior of the primary jet. Here, we ask how the jet of the secondary black hole projects onto the sky plane. Assuming that the jet is initially perpendicular to the disk, and that it is ballistic, we follow its evolution after the Lorentz transformation to the observer’s frame. Since the orbital speed of the secondary is of the order of one-tenth of the speed of light, the result is a change in the jet direction by more than a radian during an orbital cycle. We match the theoretical jet line with the recent 12 μ as resolution RadioAstron map of OJ 287 and determine the only free parameter of the problem, the apparent speed of the jet relative to speed of light. It turns out that the Doppler factor of the jet, δ ∼ 5, is much lower than in the primary jet. Besides following a unique shape of the jet path, the secondary jet is also distinguished by a different spectral shape than in the primary jet. The present result on the spectral shape agrees with the huge optical flare of 2021 November 12, also arising from the secondary jet.}, archive = {J_ApJ}, author = {Mauri J. Valtonen and Lankeswar Dey and Staszek Zola and Alok C. Gupta and Shubham Kishore and Achamveedu Gopakumar and Paul J. Wiita and Minfeng Gu and Kari Nilsson and Zhongli Zhang and Rene Hudec and Katsura Matsumoto and Marek Drozdz and Waldemar Ogloza and Andrei V. Berdyugin and Daniel E. Reichart and Markus Mugrauer and Tapio Pursimo and Stefano Ciprini and Tatsuya Nakaoka and Makoto Uemura and Ryo Imazawa and Michal Zejmo and Vladimir V. Kouprianov and James W. Davidson and Alberto Sadun and Jan Štrobl and Martin Jelínek and Abhimanyu Susobhanan}, doi = {10.3847/1538-4357/ae057e}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {110}, shortjournal = {The Astrophys. J.}, title = {Identifying the secondary jet in the RadioAstron image of OJ 287}, volume = {992}, year = {2025}, }
• (2025). New metrics for identifying variables and transients in large astronomical surveys. ApJ, 992(1), 109. (www)

  @article{ , abstract = {A key science goal of large sky surveys such as those conducted by the Vera C. Rubin Observatory and precursors to the Square Kilometre Array is the identification of variable and transient objects. One approach is analyzing time series of the changing brightness of sources, namely, light curves. However, finding adequate statistical representations of light curves is challenging because of the sparsity of observations, irregular sampling, and nuisance factors inherent in astronomical data collection. The wide diversity of objects that a large-scale survey will observe also means that making parametric assumptions about the shape of light curves is problematic. We present a Gaussian process (GP) regression approach for characterizing light-curve variability that addresses these challenges. Our approach makes no assumptions about the shape of a light curve and, therefore, is general enough to detect a range of variable and transient source types. In particular, we propose using the joint distribution of GP amplitude hyperparameters to distinguish variable and transient candidates from nominally stable ones and apply this approach to 6394 radio light curves from the ThunderKAT survey. We compare our results with two variability metrics commonly used in radio astronomy, namely η ν and V ν , and show that our approach has better discriminatory power and interpretability. Finally, we conduct a rudimentary search for transient sources in the ThunderKAT data set to demonstrate how our approach might be used as an initial screening tool. Computational notebooks in Python and R are available to help deploy this framework to other surveys.}, archive = {J_ApJ}, author = {Shih Ching Fu and Arash Bahramian and Aloke Phatak and James C. A. Miller-Jones and Suman Rakshit and Alexander Andersson and Robert Fender and Patrick A. Woudt}, doi = {10.3847/1538-4357/adfb79}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {109}, shortjournal = {The Astrophys. J.}, title = {New metrics for identifying variables and transients in large astronomical surveys}, volume = {992}, year = {2025}, }
• (2025). Mass loss and subsequent thermal evolution of surviving helium white dwarfs shocked by thermonuclear supernovae. ApJ, 992(1), 108. (www)

  @article{ , abstract = {Following a Type Ia supernova (SN Ia) in a double white dwarf (WD) binary, a surviving WD companion leaves at its orbital velocity ≈ 1000–3000 km s –1 . The Gaia mission has discovered seven such hypervelocity WDs with inflated radii indicative of shock heating by SN ejecta. We study the interaction between SN ejecta and Roche lobe filling, 0.08–0.45 M ⊙ helium WD companions using 3D hydrodynamical simulations with Athena++ . Given the importance of the later thermal evolution, we include an accurate equation of state for the degenerate helium WD donor. We show that a lower-mass, larger-radius WD companion is more strongly impacted by SN ejecta and undergoes substantial mass loss. We find a tight relation between the fractional mass loss and the ratio between the ejecta ram pressure and donor volume-averaged pressure, which can be used for predicting mass loss in other systems. In the most extreme case, the companion becomes a very inflated ≈0.02 M ⊙ object. We find helium mass loss ≈ 0.005−0.06 M ⊙ with velocities ≈ 1000−4000 km s −1 , which may lead to emission lines in the nebular phase. The surviving helium WD receives a kick velocity, but its final velocity is essentially determined by its orbital velocity, ≲1600 km s −1 . We model the postexplosion evolution of the shock-heated companions using MESA , and find reasonable agreement with the hypervelocity stars D6-2, J0546+0836, J1332–3541, and SDSS J1637+3631. A surviving ≳0.3 M ⊙ helium WD can be ruled out in SN 1972E and SN 2011fe, and any surviving helium WD is likely ruled out in SN remnants 0509-67.5 and SN 1006.}, archive = {J_ApJ}, author = {Tin Long Sunny Wong and Lars Bildsten}, doi = {10.3847/1538-4357/adfcd7}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {108}, shortjournal = {The Astrophys. J.}, title = {Mass loss and subsequent thermal evolution of surviving helium white dwarfs shocked by thermonuclear supernovae}, volume = {992}, year = {2025}, }
• (2025). Betelgeuse’s buddy: X-ray constraints on the nature of α ori b. ApJ, 992(1), 107. (www)

  @article{ , abstract = {The ∼2100 daylong secondary period of Betelgeuse’s optical lightcurve and radial velocity motivated the prediction of a low-mass stellar companion, expected to be at maximal apparent separation from Betelgeuse around 2024 December. We carried out Director’s Discretionary Time observations with the Chandra X-ray Observatory to identify any X-ray emission from the companion and constrain its nature as either a compact object or young stellar object (YSO). Past X-ray observations occurred at the wrong phase of the companion’s orbit for optimal detection prospects and/or lacked the deep exposure required to constrain the typical X-ray luminosities of YSOs. In our 41.85 ks exposure with Chandra, we do not detect an X-ray source at the position of Betelgeuse. For an estimated hydrogen column density N H = 6 × 10 22 cm −2 , we place a limit on the X-ray luminosity L X ≲ 2 × 10 30 erg s −1 (≲4.7 × 10 −4 L ⊙ ) in 0.5–8 keV for a 10 MK plasma temperature spectral model, or L X ≲ 5 × 10 29 erg s −1 (≲1.2 × 10 −4 L ⊙ ) for an absorbed power law with photon index Γ = 2. These limits robustly exclude an accreting compact object (white dwarf or neutron star) as the companion. Solar-mass YSOs with an age similar to Betelgeuse (∼10 Myr) display a range of X-ray luminosities (10 28−32 erg s −1 ), and we can place upper bounds within this range for most absorbing columns. Based on these considerations, we conclude that the companion to Betelgeuse is likely a low-mass YSO.}, archive = {J_ApJ}, author = {Anna J. G. O’Grady and Brendan O’Connor and Jared A. Goldberg and Meridith Joyce and László Molnár and Christian I. Johnson and Jeremy Hare and Katelyn Breivik and Maria R. Drout and Maxwell Moe and Annalisa Calamida}, doi = {10.3847/1538-4357/adff83}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {107}, shortjournal = {The Astrophys. J.}, title = {Betelgeuse’s buddy: X-ray constraints on the nature of α ori b}, volume = {992}, year = {2025}, }
• (2025). The HST legacy archival uniform reduction of local group imaging (LAURELIN). i. photometry and star formation histories for 36 ultra-faint dwarf galaxies. ApJ, 992(1), 106. (www)

  @article{ , abstract = {We present uniformly measured resolved stellar photometry and star formation histories (SFHs) for 36 nearby (≲400 kpc) ultra-faint dwarf galaxies (UFDs; −7.1 ≤ M V ≤ +0.0) from new and archival Hubble Space Telescope (HST) imaging. We measure homogeneous distances to all systems via isochrone fitting and find good agreement (≤2%) for the 18 UFDs that have literature RR Lyrae distances. From the ensemble of SFHs, we find (i) an average quenching time (here defined as the lookback time by which 80% of the stellar mass formed, τ 80 ) of 12.48  ±  0.18 Gyr ago ( z=4.{6}_{-0.5}^{+0.6} ), which is compatible with reionization-based quenching scenarios; and (ii) modest evidence of a delay (≲800 Myr) in quenching times of UFDs thought to be satellites of the LMC or on their first infall, relative to long-term Galactic satellites, which is consistent with previous findings. We show that robust SFH measurement via the ancient main-sequence turnoff (MSTO) requires a minimum effective luminosity (i.e., luminosity within the observed field of view) of M V ≤ −2.5, which corresponds to ∼100 stars around the MSTO. We also find that increasing the signal-to-noise ratio above ∼100 at the MSTO does not improve SFH precision, which remains dominated by stochastic effects associated with the number of available stars. A main challenge driving the precision of UFD SFHs is the limitations in the accuracy of foreground dust maps. We make all photometry catalogs public as the first data release of a larger HST archival program targeting all dwarf galaxies within ∼1.3 Mpc.}, archive = {J_ApJ}, author = {Meredith J. Durbin and Yumi Choi and Alessandro Savino and Daniel R. Weisz and Andrew E. Dolphin and Julianne J. Dalcanton and Myoungwon Jeon and Nitya Kallivayalil and Ting S. Li and Andrew B. Pace and Ekta Patel and Elena Sacchi and Evan D. Skillman and Sangmo Tony Sohn and Roeland P. van der Marel and Andrew Wetzel and Benjamin F. Williams}, doi = {10.3847/1538-4357/ae00c8}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {106}, shortjournal = {The Astrophys. J.}, title = {The HST legacy archival uniform reduction of local group imaging (LAURELIN). i. photometry and star formation histories for 36 ultra-faint dwarf galaxies}, volume = {992}, year = {2025}, }
• (2025). Characterizing the nature of periodic amplitude modulation in pulsars. ApJ, 992(1), 105. (www)

  @article{ , abstract = {In recent years, periodic amplitude modulation has emerged as a unique emission feature in the single-pulse sequence of pulsars alongside periodic nulling and subpulse drifting. Despite ample evidence for the uniqueness of this phenomenon, the periodic modulation in several pulsars are often confused with subpulse drifting, primarily due to lack of clear characterization of the emission features from a representative sample of pulsars. In this work, we present a detailed analysis of the single-pulse behavior from 17 pulsars exhibiting periodic amplitude modulation, 6 of them being new detections. The pulsar switches between different intensity states as a result of periodic amplitude modulation, and we propose a novel statistical scheme to identify these emission states. The periodic modulation can be divided into three broad categories: phase stationary modulation, modulations with phase shift, and intermittent periodic modulations. The phase stationary behavior is seen when the emission intensity across a major part of the pulse window changes periodically. The phase shifts are associated with intensity changes at specific locations within the emission window in a periodic manner, while in some pulsars, the periodic modulations become more prominent only at specific intervals resulting in intermittent behavior.}, archive = {J_ApJ}, author = {Rahul Basu and Dipanjan Mitra and George I. Melikidze}, doi = {10.3847/1538-4357/ae03c1}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {105}, shortjournal = {The Astrophys. J.}, title = {Characterizing the nature of periodic amplitude modulation in pulsars}, volume = {992}, year = {2025}, }
• (2025). Magnitude of short-wavelength electric field fluctuations in simulations of collisionless plasma shocks. ApJ, 992(1), 104. (www)

  @article{ , abstract = {Large-amplitude electrostatic fluctuations are routinely observed by spacecraft upon traversal of collisionless shocks in the heliosphere. Kinetic simulations of shocks have struggled to reproduce the amplitude of such fluctuations, complicating efforts to understand their influence on energy dissipation and shock structure. In this paper, one-dimensional particle-in-cell simulations with realistic proton-to-electron mass ratio are used to show that in cases with upstream electron temperature T e exceeding the ion temperature T i , the magnitude of the fluctuations increases with the electron plasma-to-cyclotron frequency ratio ω pe /Ω ce , reaching realistic values at ω pe /Ω ce ≳  30. The large-amplitude fluctuations in the simulations are shown to be associated with electrostatic solitary structures, such as ion phase-space holes. In the cases where upstream temperature ratio is reversed, the magnitude of the fluctuations remains small.}, archive = {J_ApJ}, author = {Vadim Roytershteyn and Lynn B. Wilson and Li-Jen Chen and Michael Gedalin and Nikolai Pogorelov}, doi = {10.3847/1538-4357/ae06a9}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {104}, shortjournal = {The Astrophys. J.}, title = {Magnitude of short-wavelength electric field fluctuations in simulations of collisionless plasma shocks}, volume = {992}, year = {2025}, }
• (2025). Impact of gravity on changing magnetic field orientations in a sample of massive protostellar clusters observed with ALMA. ApJ, 992(1), 103. (www)

  @article{ , abstract = {The magnetic field is integral to our understanding of the formation and dynamical evolution of molecular clouds and star formation within. We present a polarimetric survey of 17 massive protostellar cluster forming clumps, covered in 34 pointings in the 230 GHz window using the Atacama Large Millimeter/submillimeter Array. The two array configurations, C43-1 and C43-4, probe linearly polarized dust emission, hence the plane-of-the-sky orientation of magnetic fields, at resolutions of 1 ″ and 0 \mathop{.}\limits^{\prime\prime} 4 that correspond to approximately 0.01 pc core and 10 3 au envelope scales, respectively. The relative orientations (ROs) of the magnetic field probed at two spatial scales are analyzed for the entire protostellar cluster sample and for a subset of objects in NGC 6334. We found a bimodal distribution of ROs with peaks at 0° (parallel) and 90° (orthogonal) for the entire sample combined, as well as for NGC 6334. We investigate the physical origin of this bimodal distribution through a projected Rayleigh statistical analysis in relation to column densities and local gravity in NGC 6334. We found an excess of parallel magnetic fields at column densities >10 23 cm −2 . The underlying cause of the RO distribution of the magnetic field is gravitational collapse at higher gas densities, which drags and reorients the magnetic field as shown in the alignment between the magnetic field and the direction of gravitational forces. The distribution of ROs observed here is consistent with the evolution of ROs of an initially sub-Alvénic cloud that becomes magnetically supercritical and super-Alvénic as the cloud collapses to form stars.}, archive = {J_ApJ}, author = {Qizhou Zhang and Junhao Liu and Lingzhen Zeng and J. D. Soler and Huei-Ru Vivien Chen and Tao-Chung Ching and Paul T. P. Ho and Josep Miquel Girart and Patrick M. Koch and Shih-Ping Lai and Shanghuo Li and Zhi-Yun Li and Hauyu Baobab Liu and Keping Qiu and Ramprasad Rao}, doi = {10.3847/1538-4357/adfdcb}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {103}, shortjournal = {The Astrophys. J.}, title = {Impact of gravity on changing magnetic field orientations in a sample of massive protostellar clusters observed with ALMA}, volume = {992}, year = {2025}, }
• (2025). Probing the nature of gravity in the low-acceleration limit: Wide binaries of extreme separations with perspective effects. ApJ, 992(1), 102. (www)

  @article{ , abstract = {Recent statistical analyses of wide binaries have revealed a boost in gravitational acceleration with respect to the prediction by Newtonian gravity at low internal accelerations ≲10 −9 m s −2 . This phenomenon is important because it does not permit the dark matter interpretation, unlike galaxy rotation curves. We extend previous analyses by increasing the maximum sky-projected separation from 30 to 50 kilo astronomical units (kau). We show that the so-called “perspective effects” are not negligible at this extended separation and, thus, incorporate it in our analysis. With wide binaries selected with very stringent criteria, we find that the gravitational acceleration boost factor, γ g ≡ g obs / g N , is 1.6{1}_{-0.29}^{+0.37} (from {\delta }_{{\rm{obs}}-{\rm{newt}}}\equiv ({\mathrm{log}}\,_{10}{\gamma }_{g})/\sqrt{2}=0.147\pm 0.062 ) at Newtonian accelerations g N = 10 −11.0 m s −2 , corresponding to separations of tens of kau for solar mass binaries. At Newtonian accelerations g N = 10 −10.3 m s −2 , we find {\gamma }_{g}=1.2{6}_{-0.10}^{+0.12} ( δ obs−newt = 0.072 ± 0.027). For all binaries with g N ≲ 10 −10 m s −2 from our sample, we find {\gamma }_{g}=1.3{2}_{-0.11}^{+0.12} ( δ obs−newt = 0.085 ± 0.027). These results are consistent with the generic prediction of modified Newtonian dynamics-type modified gravity, although the current data are not sufficient to pin down the low-acceleration limiting behavior. Finally, we emphasize that the observed deviation from Newtonian gravity cannot be explained by the perspective effects or any separation-dependent eccentricity variation that we have taken into account.}, archive = {J_ApJ}, author = {Youngsub Yoon and Yong Tian and Kyu-Hyun Chae}, doi = {10.3847/1538-4357/ae0190}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {102}, shortjournal = {The Astrophys. J.}, title = {Probing the nature of gravity in the low-acceleration limit: Wide binaries of extreme separations with perspective effects}, volume = {992}, year = {2025}, }
• (2025). On the stability analysis of astrophysical cooling functions. ApJ, 992(1), 101. (www)

  @article{ , abstract = {To model the temperature evolution of optically thin astrophysical environments at MHD scales, radiative and collisional cooling rates are typically either pretabulated or fit into a functional form and then input into MHD codes as a radiative loss function. Thermal balance requires estimates of the analogous heating rates, which are harder to calculate, and due to uncertainties in the underlying dissipative heating processes these rates are often simply parameterized. The resulting net cooling function defines an equilibrium curve that varies with density and temperature. Such cooling functions can make the gas prone to thermal instability (TI), which will cause departures from equilibrium. There has been no systematic study of thermally unstable parameter space for nonequilibrium states. Motivated by our recent finding that there is a related linear instability, catastrophic cooling instability, that can dominate over TI, here we carry out such a study. We show that Balbus instability criteria for TI can be used to define a critical cooling rate, Λ c , that permits a nonequilibrium analysis of cooling functions through the mapping of TI zones. We furthermore illustrate how thermal conduction modifies the shape of TI zones. Upon applying a Λ c -based stability analysis to coronal loop simulations, we find that loops undergoing periodic episodes of coronal rain formation are linearly unstable to catastrophic cooling instability, while TI is stabilized by thermal conduction.}, archive = {J_ApJ}, author = {Amanda Stricklan and Tim Waters and James Klimchuk}, doi = {10.3847/1538-4357/adf960}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {101}, shortjournal = {The Astrophys. J.}, title = {On the stability analysis of astrophysical cooling functions}, volume = {992}, year = {2025}, }
• (2025). Final moments. III. explosion properties and progenitor constraints of CSM-interacting type II supernovae. ApJ, 992(1), 100. (www)

  @article{ , abstract = {We present analysis of the plateau and late-time phase properties of a sample of 39 Type II supernovae (SNe II) that show narrow, transient, high-ionization emission lines (i.e., “IIn-like”) in their early-time spectra from interaction with confined, dense circumstellar material (CSM). Originally presented by W. V. Jacobson-Galán et al., this sample also includes multicolor light curves and spectra extending to late-time phases of 35 SNe with no evidence for IIn-like features at <2 days after first light. We measure photospheric phase light-curve properties for the distance-corrected sample and find that SNe II with IIn-like features have significantly higher luminosities and decline rates at +50 days than the comparison sample, which could be connected to inflated progenitor radii, lower ejecta mass, and/or persistent CSM interaction. However, we find no statistical evidence that the measured plateau durations and 56 Ni masses of SNe II with and without IIn-like features arise from different distributions. We estimate progenitor zero-age main-sequence (ZAMS) masses for all SNe with nebular spectroscopy through spectral model comparisons and find that most objects, both with and without IIn-like features, are consistent with progenitor masses ≤12.5 M ⊙ . Combining progenitor ZAMS masses with CSM densities inferred from early-time spectra suggests multiple channels for enhanced mass loss in the final years before core collapse, such as a convection-driven chromosphere or binary interaction. Finally, we find spectroscopic evidence for ongoing ejecta-CSM interaction at radii >10 16 cm, consistent with substantial progenitor mass-loss rates of ∼10 −4 –10 −5 M ⊙ yr −1 ( v w < 50 km s −1 ) in the final centuries to millennia before explosion.}, archive = {J_ApJ}, author = {W. V. Jacobson-Galán and L. Dessart and K. W. Davis and K. A. Bostroem and C. D. Kilpatrick and R. Margutti and A. V. Filippenko and R. J. Foley and R. Chornock and G. Terreran and D. Hiramatsu and M. Newsome and E. Padilla Gonzalez and C. Pellegrino and D. A. Howell and J. P. Anderson and C. R. Angus and K. Auchettl and T. G. Brink and R. Cartier and D. A. Coulter and T. de Boer and M. R. Drout and N. Earl and K. Ertini and J. R. Farah and D. Farias and C. Gall and H. Gao and M. A. Gerlach and F. Guo and A. Haynie and G. Hosseinzadeh and A. L. Ibik and S. W. Jha and D. O. Jones and D. Langeroodi and N. LeBaron and E. A. Magnier and A. L. Piro and S. I. Raimundo and A. Rest and S. Rest and R. Michael Rich and C. Rojas-Bravo and H. Sears and K. Taggart and V. A. Villar and R. J. Wainscoat and X.-F. Wang and A. R. Wasserman and S. Yan and Y. Yang and J. Zhang and W. Zheng}, doi = {10.3847/1538-4357/adfa23}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {100}, shortjournal = {The Astrophys. J.}, title = {Final moments. III. explosion properties and progenitor constraints of CSM-interacting type II supernovae}, volume = {992}, year = {2025}, }
• (2025). Predicting solar magnetic activity from sph and seismic parameters using random forest regression. ApJ, 992(1), 99. (www)

  @article{ , abstract = {We investigate the potential of using the photometric magnetic proxy S ph and seismic parameters, such as the frequency of maximum power ( ν max ) and the large frequency separation (Δ ν ), derived from Solar and Heliospheric Observatory/Variability of Solar Irradiance and Gravity Oscillations observations to predict the 10.7 cm solar radio flux, a widely used index of solar magnetic activity. A random forest regression model is trained and tested on time series divided into multiple temporal subsets and input parameter combinations. The model achieves strong predictive performance ( R 2 > 0.92) across configurations and significantly outperforms a classical linear regression model. Our results show that S ph effectively captures long-term variations, while the seismic amplitude parameter H max is more responsive to short-term fluctuations. Combining S ph with the full set of seismic parameters yields the highest accuracy and offers a promising approach for diagnosing activity in other solar-like stars where direct magnetic field measurements are infeasible.}, archive = {J_ApJ}, author = {Ki-Beom Kim and Heon-Young Chang}, doi = {10.3847/1538-4357/adfe6a}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {99}, shortjournal = {The Astrophys. J.}, title = {Predicting solar magnetic activity from sph and seismic parameters using random forest regression}, volume = {992}, year = {2025}, }
• (2025). ALMA observations of CO in five planetary nebulae: Insights into nebular shaping. ApJ, 992(1), 98. (www)

  @article{ , abstract = {The J = 2→1 transition of CO near 230 GHz has been imaged in five bipolar/multipolar planetary nebulae (K3-45, K3-58, M1-7, M2-48, and M3-28) using ALMA with 1″ angular resolution. Single-dish data from the Arizona Radio Observatory Submillimeter Telescope (ARO SMT) were added to provide sensitivity on spatial scales up to 30″—essential for these data. The images show that the molecular gas resides primarily in the central regions of the nebulae and not in the bipolar flows of the optical images. CO appears to trace the remnant asymptotic giant branch (AGB) wind ( V exp ∼ 12–14 km s −1 ) but has a higher velocity component ( V > 16–23 km s −1 ) that represents gas swept up in the outflows. The orientations, with respect to the plane of the sky, of the bipolar outflows are 45° ± 5, 65° ± 10, and 65° ± 5 for K3–45, K3-58, and M1-7, respectively, with the blueshifted lobes oriented to the NE, W, and NW. For M2-48 and M3-28, the flows lie in the plane of the sky, with the blueshifted lobes roughly lying E and N. Based on CO, velocities in the bipolar flows are estimated to be V outflow > 18–31 km s −1 . Revised CO column densities are consistent with past measurements, except for M2-48, where the value increased to N tot ∼ 9.3{\rm{\times }}{10}^{16} cm −2 ; a value was also obtained for the first time for K3-58 ( N tot ∼ 5 × 10 16 cm −2 ). Given the unusual 12 C/ 13 C ratios observed in two sources, the bipolar ejection may have an origin in runaway He-burning in the late AGB phase.}, archive = {J_ApJ}, author = {D. R. Schmidt and K. R. Gold and H. Liszt and L. M. Ziurys}, doi = {10.3847/1538-4357/ae0037}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {98}, shortjournal = {The Astrophys. J.}, title = {ALMA observations of CO in five planetary nebulae: Insights into nebular shaping}, volume = {992}, year = {2025}, }
• (2025). The frequency-independent radio Luminosity–Orbital/Rotational period relation of RS CVn stars. ApJ, 992(1), 97. (www)

  @article{ , abstract = {Radio emissions from RS CVn objects exhibit distinct characteristics at low and high frequencies, widely attributed to differing radiation mechanisms. The disparate processes of high-frequency gyrosynchrotron and low-frequency electron cyclotron maser emissions have traditionally suggested an absence of correlation in their radio luminosities. Our study presents a frequency-independent linear correlation between radio luminosity ( L R ) and orbital/rotational periods ( P ) in RS CVn binaries. Analyzing the Sydney Radio Star Catalogue data, we derived orbital periods for 42 of 60 RS CVn sources using Transiting Exoplanet Survey Satellite light curves, revealing a strong positive correlation (Pearson correlation coefficient (PCC) = 0.698 and P = 3.95e-7) between {\mathrm{log}}\,_{10}{L}_{R} and {\mathrm{log}}\,_{10}P . This correlation remains across frequencies from 144 to 3000 MHz, showing uniform luminosity behavior. By combining light curve analysis with stellar mass–radius–luminosity relationships, we calculated parameters like binary mass, primary/secondary mass, Rossby number, and binary separation for eight RS CVn systems. The results show a notable correlation between radio luminosity and binary mass, primary mass, and separation (PCC = 0.663, 0.663, and 0.719), with separation showing the strongest correlation. This suggests the radio emission may largely originate from the binary components’ interaction, challenging existing models of RS CVn radio emission mechanisms and offering insights into the individual versus collective origins of these emissions.}, archive = {J_ApJ}, author = {Qichen Huang and Biwei Jiang}, doi = {10.3847/1538-4357/ae003c}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {97}, shortjournal = {The Astrophys. J.}, title = {The frequency-independent radio Luminosity–Orbital/Rotational period relation of RS CVn stars}, volume = {992}, year = {2025}, }
• (2025). The near infrared spectral energy distribution of young star clusters in the FEAST galaxies: Missing ingredients at 1–5 μm. ApJ, 992(1), 96. (www)

  @article{ , abstract = {We present a combined Hubble Space Telescope (HST) and JWST 0.2–to–5 μ m analysis of the spectral energy distributions (SED) of emerging young star clusters (eYSCs) in four nearby galaxies from the Feedback in Emerging Extrgalactic Star Clusters survey: M51, M83, NGC 628, and NGC 4449. These clusters, selected for their bright Pa α and 3.3 μ m polycyclic aromatic hydrocarbon emission, are still associated with their natal gas cloud and have been largely missed in previous HST optical campaigns. We modeled their SEDs using the CIGALE fitting code and identified (i) a systematic flux excess at 1.5–2.5 μ m that is not accounted for by current stellar population models and (ii) the preference for a set of dust model parameters that is not aligned with expectations from self-consistent analyses of star-forming regions, suggesting model shortcomings also in the 3–5 μ m. The near-infrared excess is most prominent in low-mass (≤3000 M ⊙ ) and young (≤6 Myr) clusters. Additionally, we see that the SED fitting analysis wrongly assigns ages ≥6 Myr to a fraction of strong Pa α emitters with equivalent widths suggestive of significantly younger ages. A parallel analysis with the slug code suggests that stochastic initial mass function (IMF) sampling of pre-main-sequence stars combined with extinction might partially reduce the gap. We conclude that the inclusion of young stellar object SEDs, along with more realistic sampling of the cluster IMF, might be needed to fully account for the stellar population and dust properties of eYSCs.}, archive = {J_ApJ}, author = {Alex Pedrini and Angela Adamo and Arjan Bik and Daniela Calzetti and Sean T. Linden and Benjamin Gregg and Varun Bajaj and Jenna E. Ryon and Anne S. M. Buckner and Giacomo Bortolini and Michele Cignoni and Matteo Correnti and Ana Duarte-Cabral and Bruce G. Elmegreen and Helena Faustino Vieira and John S. Gallagher and Kathryn Grasha and Kelsey E. Johnson and Mark R. Krumholz and Drew Lapeer and Thomas S.-Y. Lai and Matteo Messa and Göran Östlin and Linn Roos and Linda J. Smith and Monica Tosi}, doi = {10.3847/1538-4357/ae0182}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {96}, shortjournal = {The Astrophys. J.}, title = {The near infrared spectral energy distribution of young star clusters in the FEAST galaxies: Missing ingredients at 1–5 μm}, volume = {992}, year = {2025}, }
• (2025). Persistent behavior of low-energy solar energetic particles observed by parker solar probe during orbit 15. ApJ, 992(1), 95. (www)

  @article{ , abstract = {The paper develops a new statistical method for forecasting the arrival time and maximum flux of solar energetic particle (SEP) events. We recently showed the persistent behavior of the SEP time series during SEP events. In that study, we also used persistence to determine the onset time (OT) of an SEP event and suggested using the entropy change in a time domain called natural time under time reversal Δ S as a way to estimate the maximum SEP flux of the ongoing SEP event. Here, we use EPI-Lo data for H + below 2 MeV over the whole Orbit 15 from the Integrated Science Investigation of the Sun (IS⊙IS) instrument suite on board NASA’s Parker Solar Probe to investigate the broader applicability of these methods. We clearly demonstrate that during SEP events the corresponding time series is persistent and are able to employ the persistence-based OT method to predict SEP events. We find a prediction rate greater than 87.5% (14 out of the 16 SEP events) and a false alarm rate below 2.2%. These values when inserted in the receiver operating characteristics plane indicate that this method is highly statistically significant. Finally, we develop a relationship between the maximum SEP flux and the minimum of Δ S , allowing us to provide a prediction of the future maximum SEP flux during an ongoing event.}, archive = {J_ApJ}, author = {N. V. Sarlis and G. Livadiotis and D. J. McComas and M. E. Cuesta and L. Y. Khoo and M. M. Shen and J. S. Rankin and N. A. Schwadron}, doi = {10.3847/1538-4357/ae019b}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {95}, shortjournal = {The Astrophys. J.}, title = {Persistent behavior of low-energy solar energetic particles observed by parker solar probe during orbit 15}, volume = {992}, year = {2025}, }
• (2025). Long-period variable stars in NGC 147 and NGC 185. II. their dust production. ApJ, 992(1), 94. (www)

  @article{ , abstract = {This study presents a comparative analysis of mass-loss and dust production rates in the dwarf galaxies NGC 147 and NGC 185, focusing on long-period variables (LPVs) and pulsating asymptotic giant branch stars as primary indicators of dust feedback into the interstellar medium. For NGC 147, the total mass-loss rate is calculated as (9.44 ± 3.78) × 10 −4 M ⊙ yr −1 , with LPV luminosities ranging from (6.20 ± 0.25) × 10 2 L ⊙ to (7.87 ± 0.32) × 10 3 L ⊙ . In NGC 185, the total mass-loss rate is higher, at (1.58 ± 0.63) × 10 −3 M ⊙ yr −1 , with LPV luminosities spanning (5.68 ± 0.23) × 10 2 L ⊙ to (1.54 ± 0.66) × 10 4 L ⊙ . A positive correlation is observed between stellar luminosity, intrinsic reddening due to circumstellar dust self-extinction, and elevated mass-loss rates. Additionally, comparisons of calculated dust injection rates, two-dimensional dust distribution maps, and observed dust masses provide evidence for a gravitational interaction between NGC 147 and the Andromeda galaxy, which influences the dust distribution within the system.}, archive = {J_ApJ}, author = {Hamidreza Mahani and Atefeh Javadi and Jacco Th. van Loon and Francisca Kemper and Roya Hamedani Golshan and Iain McDonald and Habib G. Khosroshahi and Hedieh Abdollahi and Sajjad Mahdizadeh}, doi = {10.3847/1538-4357/adfa2b}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {94}, shortjournal = {The Astrophys. J.}, title = {Long-period variable stars in NGC 147 and NGC 185. II. their dust production}, volume = {992}, year = {2025}, }
• (2025). Classifying cool dwarfs: Comprehensive spectral typing of field and peculiar dwarfs using machine learning. ApJ, 992(1), 93. (www)

  @article{ , abstract = {Low-mass stars and brown dwarfs—spectral types (SpTs) M0 and later—play a significant role in studying stellar and substellar processes and demographics, reaching down to planetary-mass objects. Currently, the classification of these sources remains heavily reliant on visual inspection of spectral features, equivalent width measurements, or narrow/wideband spectral indices. Recent advances in machine learning (ML) methods offer automated approaches for spectral typing, which are becoming increasingly important as large spectroscopic surveys such as Gaia, SDSS, and SPHEREx generate data sets containing millions of spectra. We investigate the application of ML in spectral type classification on low-resolution ( R ∼ 120) near-infrared spectra of M0–T9 dwarfs obtained with the SpeX instrument on the NASA Infrared Telescope Facility. We specifically aim to classify the gravity- and metallicity-dependent subclasses for late-type dwarfs. We used binned fluxes as input features and compared the efficacy of spectral type estimators built using Random Forest (RF), Support Vector Machine, and K-Nearest Neighbor (KNN) models. We tested the influence of different normalizations and analyzed the relative importance of different spectral regions for surface gravity and metallicity subclass classification. Our best-performing model (using KNN) classifies 95.5% ± 0.6% of sources to within ±1 SpT, and assigns surface gravity and metallicity subclasses with 89.5% ± 0.9% accuracy. We test the dependence of signal-to-noise ratio on classification accuracy and find sources with SNR ≳60 have ≳95% accuracy. We also find that zy band plays the most prominent role in the RF model, with FeH and TiO having the highest feature importance.}, archive = {J_ApJ}, author = {Tianxing Zhou and Christopher A. Theissen and S. Jean Feeser and William M. J. Best and Adam J. Burgasser and Kelle L. Cruz and Lexu Zhao}, doi = {10.3847/1538-4357/adfb7d}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {93}, shortjournal = {The Astrophys. J.}, title = {Classifying cool dwarfs: Comprehensive spectral typing of field and peculiar dwarfs using machine learning}, volume = {992}, year = {2025}, }
• (2025). How dust models shape high-z galaxy morphology: Insights from the NewCluster simulation. ApJ, 992(1), 92. (www)

  @article{ , abstract = {Dust plays a pivotal role in shaping the observed morphology of galaxies. While traditional cosmological simulations often assume a fixed dust-to-gas or dust-to-metal (DTM) mass ratio to model dust effects, recent advancements have enabled on-the-fly (OTF) dust modeling that captures the spatial and temporal evolution of dust. In this work, we investigate the impact of dust modeling on galaxy morphology using the NewCluster simulation, which implements a detailed OTF dust model. We generate mock images of NewCluster galaxies under both OTF and fixed DTM models using the radiative transfer code SKIRT , and compare their morphology to JWST observations. We measure morphology indices and use the G – M 20 test to classify galaxies. We find that the OTF galaxy models exhibit brighter centers and more pronounced bulges than those of the fixed DTM models, resulting in a lower late-type galaxy fraction, particularly at high redshifts. This central brightening is linked to a phenomenon we refer to as the DTM cavity, a localized depression in the DTM ratio driven by intense bulge starbursts. Our results highlight the importance of modeling dust evolution in a physically motivated manner, as fixed DTM models fail to capture key morphological features.}, archive = {J_ApJ}, author = {Gyeong-Hwan Byun and J. K. Jang and Zachary P. Scofield and Eunmo Ahn and Maarten Baes and Yohan Dubois and San Han and Seyoung Jeon and Juhan Kim and Christophe Pichon and Jinsu Rhee and Francisco Rodríguez Montero and Sukyoung K. Yi}, doi = {10.3847/1538-4357/adfed9}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {92}, shortjournal = {The Astrophys. J.}, title = {How dust models shape high-z galaxy morphology: Insights from the NewCluster simulation}, volume = {992}, year = {2025}, }
• (2025). Lyman continuum leakage from massive leaky starbursts: A different class of emitters?. ApJ, 992(1), 91. (www)

  @article{ , abstract = {The origin of Lyman continuum (LyC) photons responsible for reionizing the Universe remains largely unknown, with the fraction of escaping LyC photons from galaxies at z ∼ 6 to 12 still uncertain. Direct detection of LyC photons from this epoch is challenging due to intergalactic medium absorption, making lower-redshift analogs valuable for studying LyC leakage. In this study, we present Hubble Space Telescope Cosmic Origins Spectrograph observations of five low-redshift ( z ∼ 0.3) massive starburst galaxies, selected for high stellar mass and weak [S II ] nebular emission, an indirect tracer of LyC escape. LyC leakage is detected in three of the five galaxies, highlighting weak [S II ] as a reliable tracer—a finding supported by recent JWST discoveries of z > 5 galaxies with similarly weak [S II ] emission. The dust-corrected LyC escape fractions ( f esc,H I ), representing LyC photons that would escape without dust, range from 33% to 84%. However, the absolute escape fractions ( f esc,tot ), accounting for both neutral hydrogen absorption and dust attenuation, are substantially lower, between 1% and 3%. This indicates that, although these galaxies are nearly optically thin to H I , their significant dust content restricts LyC escape. These [S II ]-weak, massive leakers differ from typical low-redshift LyC emitters, exhibiting higher metallicity, lower ionization states, greater dust extinction, and higher star formation surface densities. We suggest that feedback-driven winds in these compact starbursts generate ionized channels, allowing LyC escape in line with a “picket-fence” model, indicating a distinct mechanism for LyC leakage.}, archive = {J_ApJ}, author = {Namrata Roy and Timothy Heckman and Alaina Henry and John Chisholm and Sophia Flury and Claus Leitherer and Matthew J. Hayes and Anne Jaskot and Zhiyuan Ji and Daniel Schaerer and Bingjie Wang and Sanchayeeta Borthakur and Xinfeng Xu and Göran Östlin}, doi = {10.3847/1538-4357/adff5e}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {91}, shortjournal = {The Astrophys. J.}, title = {Lyman continuum leakage from massive leaky starbursts: A different class of emitters?}, volume = {992}, year = {2025}, }
• (2025). Simulations of galactic outflows driven by active galactic nuclei and starbursts. ApJ, 992(1), 90. (www)

  @article{ , abstract = {Using the hydro code Athena++ , we run a series of large-scale hydrodynamic simulations of galactic outflows on a scale of ∼5 kpc scale over a time period of 5 Myr. We compare the kinematics, composition, and simulated X-ray emission of starburst (SB) versus active galactic nuclei (AGN) dominated galactic outflows. Our set of simulations includes galactic outflows driven solely by a nuclear SB, an AGN wind, and a mixture of SBs and AGN winds. We find significant differences in the kinematics, composition, and simulated X-ray emission between SB- versus AGN-dominated outflows. Starburst-driven outflows are characterized by turbulent, multiphase, complex flows, with each phase having a distinct kinematic profile (as traced by various oxygen ions), while AGN-driven outflows are more symmetric, more single phase, with primarily very hot (>10 7 K) gas, and are smooth in appearance. In mixed SB-AGN simulations, the dominant component (SB or AGN) determines the outflow characteristics. In cases where the energy input of the SB is similar to the energy of the AGN, the resulting outflow appears similar to the SB-only outflow, but when the energy input from the AGN wind is much greater than the SB then the outflow appears similar to the AGN-only outflow. When we generate synthetic X-ray observations, the AGN-dominated outflows are essentially invisible in soft to medium-energy X-rays (0.1–10.0 keV), but the SB-driven outflows show complex filamentary structures that are visible in the X-ray. Finally, we show the observational possibilities for various proposed and future X-ray telescopes.}, archive = {J_ApJ}, author = {Ryan Tanner and Kimberly A. Weaver and Anna Ogorzałek}, doi = {10.3847/1538-4357/ae00c4}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {90}, shortjournal = {The Astrophys. J.}, title = {Simulations of galactic outflows driven by active galactic nuclei and starbursts}, volume = {992}, year = {2025}, }
• (2025). The role of farside magnetic structures in modeling the 2024 solar eclipse. ApJ, 992(1), 89. (www)

  @article{ , abstract = {The corona is a crucial region that connects the solar surface to the solar wind and serves as the primary site of solar activity. The 2024 total solar eclipse (TSE) provides a unique opportunity to investigate the large-scale coronal structure. Combined with TSE observations, we study the impact of the magnetic structure of the farside active region, located in the eastern hemisphere of the Sun that has not yet rotated into the Earth field of view, on a global magnetohydrodynamic simulation. To address the limitation of single-view measurements for the routine synoptic map, we correct the magnetic field in the farside region by incorporating full-disk magnetograms measured several days after the TSE, allowing us to capture the temporal evolution of the photospheric magnetic field in near real time. Simulation results demonstrate that the local magnetic field in the farside active region can significantly influence the global coronal structure, by altering the position of the heliospheric current sheet, and further affect the global distribution of plasma parameters, even in polar regions. A comparison of the simulation results with white-light TSE + Large Angle and Spectrometric Coronagraph C2 observations and in situ measurements by the Parker Solar Probe reveals that the composite synoptic map improves the accuracy of the coronal modeling. This work provides robust support for advancing our understanding of coronal evolution, as well as deepening the link between the photosphere and large-scale coronal structure. Furthermore, it establishes a theoretical foundation for the future development of multiview stereoscopic measurements of the photospheric magnetic field.}, archive = {J_ApJ}, author = {Guanglu Shi and Jiahui Shan and Li Feng and Jun Chen and Weiqun Gan}, doi = {10.3847/1538-4357/ae0323}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {89}, shortjournal = {The Astrophys. J.}, title = {The role of farside magnetic structures in modeling the 2024 solar eclipse}, volume = {992}, year = {2025}, }
• (2025). Radial profiles of radio halos in massive galaxy clusters: Diffuse giants over 2 mpc. ApJ, 992(1), 88. (www)

  @article{ , abstract = {We present new, high frequency radio observations of the merging galaxy clusters PLCK G287.0+32.9, A2744, and Bullet. These clusters are known to host ∼Mpc scale sources, known as radio halos, which are formed by the acceleration of cosmic rays by turbulence injected into the intracluster medium during cluster mergers. Our new images reveal previously undetected faint outermost regions of halos, extending to over 2 Mpc. This discovery highlights the presence of radio halos with large extents at high frequencies and suggests that their observable size depends on a combination of the observation sensitivity and uv -coverage, as well as their radio power. We additionally compare the properties of these three clusters with MACS J0717+3745 and A2142, both of which are known to host prominent large radio halos. Remarkably, all five halos, despite their exceptionally large extents, exhibit properties similar to other classical halos: their radial profiles are described by a single-component exponential fit, they show radial spectral index steepening, and have an average radio emissivity of about 10 −42 erg s −1 cm −3 Hz −1 . Our results demonstrate that radio halos can extend to the cluster’s periphery, without the transition to an observationally distinguishable different halo component in the outermost regions. Our findings also highlight that careful subtraction of unrelated sources embedded in the halo is necessary to measure the radio surface brightness accurately, since incomplete subtraction can introduce an apparent secondary component in the peripheral regions.}, archive = {J_ApJ}, author = {K. Rajpurohit and A. Botteon and E. O’Sullivan and W. Forman and M. Balboni and L. Bruno and R. J. van Weeren and M. Hoeft and G. Brunetti and C. Jones and A. S. Rajpurohit and S. P. Sikhosana}, doi = {10.3847/1538-4357/adfd59}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {88}, shortjournal = {The Astrophys. J.}, title = {Radial profiles of radio halos in massive galaxy clusters: Diffuse giants over 2 mpc}, volume = {992}, year = {2025}, }
• (2025). Lyα emission from k and m dwarfs: Intrinsic profiles, variability, and flux in the habitable zone. ApJ, 992(1), 87. (www)

  @article{ , abstract = {Lyman-alpha (Ly α ) is the most prominent ultraviolet (UV) emission line in low-mass stars, playing a crucial role in exoplanet atmospheric photochemistry, heating, and escape. However, interstellar medium (ISM) absorption typically obscures most of the Ly α profile, requiring reconstructions that introduce systematic uncertainties. We present intrinsic Ly α profiles for 12 high-radial-velocity (RV) K and M dwarfs, where Doppler shifting minimizes ISM contamination, allowing direct measurements of ∼50%–95% of the line flux. Our sample spans the K-to-M spectral transition, enabling us to constrain the dependence of self-reversals in Ly α emission profiles on effective temperature ( T eff ). The depth of self-reversal, driven by non–local thermodynamic equilibrium effects, decreases with decreasing T eff , with M dwarfs exhibiting little to none. Two stars, Ross 1044 and Ross 451, were observed over multiple days, revealing ∼20% Ly α variability confined to the line core—implying that studies relying on reconstructions may underestimate temporal variability. We find strong correlations between Ly α flux, peak-to-trough ratio, and hydrogen departure coefficients with T eff , providing empirical constraints for stellar atmosphere models. A comparison of Ly α flux in the habitable zone shows measured values for high-RV stars less than the reconstructed values for the rest of the sample, likely due to the older ages of the high-RV stars and/or overestimated reconstructed fluxes due to model deficiency (e.g., neglecting self-reversal). Our results establish an empirical foundation for Ly α emission in K and M dwarfs, reducing uncertainties in reconstructions and improving models of stellar UV emission relevant to exoplanetary studies.}, archive = {J_ApJ}, author = {Sarah Peacock and Travis S. Barman and R. O. Parke Loyd and Adam C. Schneider and Allison Youngblood and Kenneth G. Carpenter and Evgenya L. Shkolnik}, doi = {10.3847/1538-4357/ae00c1}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {87}, shortjournal = {The Astrophys. J.}, title = {Lyα emission from k and m dwarfs: Intrinsic profiles, variability, and flux in the habitable zone}, volume = {992}, year = {2025}, }
• (2025). Discovery of giant bubbles in the hot gaseous halo of the massive disk galaxy NGC 6286. ApJ, 992(1), 86. (www)

  @article{ , abstract = {Based on archival Chandra X-ray observation, optical integral-field spectroscopic data, and radio interferometric data, we report the discovery of a pair of giant bubbles (with a projected radius ∼5 kpc) of ionized gas emerging from a highly inclined starburst galaxy NGC 6286, which is undergoing strong tidal interactions with its close neighbor NGC 6285. The bubbles are manifested by extraplanar soft X-ray emission with an X-shaped morphology, which is tightly cospatial with H α line emission and partially coincident with radio continuum. Low surface brightness diffuse X-ray emission can be traced out to ∼90 kpc from the galactic center, revealing the presence of an extended hot gaseous halo. X-ray spectral analysis of the bubbles yields a gas temperature of 0.7{0}_{-0.18}^{+0.16} keV, a relatively high value among known galactic-scale bubbles in the local Universe. An average energy injection rate of ∼10 43 erg s −1 is required to inflate the bubbles within an estimated dynamical age of ∼6.4 Myr. The multiwavelength properties of the bubbles can be understood with the conventional superwind scenario, in which disk/halo gas is swept up into an expanding, cooling shell by a hot tenuous wind. The current starburst in NGC 6286 is energetically sufficient to launch the superwind, although we cannot rule out the possibility of a more violent active galactic nucleus in the recent past as the driving source. Future high-resolution spectroscopic observations will help to shed light on the origin of the superwind and its role as an important galactic feedback process.}, archive = {J_ApJ}, author = {Lin He and Zhiyuan Li and Zongnan Li and Rubén García-Benito and Yuanqi Liu and Meicun Hou}, doi = {10.3847/1538-4357/ae0722}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {86}, shortjournal = {The Astrophys. J.}, title = {Discovery of giant bubbles in the hot gaseous halo of the massive disk galaxy NGC 6286}, volume = {992}, year = {2025}, }
• (2025). Radiative nonideal magnetohydrodynamic simulations of inner protoplanetary disks: Temperature structures, asymmetric winds, and episodic surface accretion. ApJ, 992(1), 85. (www)

  @article{ , abstract = {We perform 2D global magnetohydrodynamic (MHD) simulations including the full nonideal MHD effects (ohmic diffusion, Hall effect, and ambipolar diffusion) and approximate radiation transport to understand the dynamics and thermal structure of the inner protoplanetary disks (PPDs). We have developed a simple radiative transfer model for PPDs that reasonably treats stellar nonthermal (X-ray and ultraviolet (XUV)), stellar thermal (optical/infrared), and reemitted radiation, reproducing the temperature structures from Monte Carlo radiative transfer. Our simulations show fast one-sided surface accretion (∼10% of Keplerian velocity) and asymmetric disk winds when the vertical magnetic field is aligned with the disk angular momentum. The asymmetry is due to the failure of the wind on the side with the accretion layer. On the accreting surface, clumps are repeatedly generated and accrete, driven by radiative feedback. For the antialigned fields, surface accretion becomes more moderate and time variable, while the winds remain largely symmetric. For the thermal structure, accretion heating does not affect the disk temperature in any of our runs. This is because (1) the accretion energy dissipates via Joule heating at two to three gas scale heights, where low optical depth enables efficient radiative cooling, and (2) the winds remove ≳10% of the accretion energy. In contrast, the winds enhance radiative heating by elevating the irradiation front. These results highlight the importance of coupling between gas dynamics and radiation transport in PPDs and provide observable magnetic activities such as fast episodic accretion, wind asymmetry, and molecular survival in XUV-irradiated winds.}, archive = {J_ApJ}, author = {Shoji Mori and Xue-Ning Bai and Kengo Tomida}, doi = {10.3847/1538-4357/adf8d7}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {85}, shortjournal = {The Astrophys. J.}, title = {Radiative nonideal magnetohydrodynamic simulations of inner protoplanetary disks: Temperature structures, asymmetric winds, and episodic surface accretion}, volume = {992}, year = {2025}, }
• (2025). Deep potential: Recovering the gravitational potential and local pattern speed in the solar neighborhood with GDR3 using normalizing flows. ApJ, 992(1), 84. (www)

  @article{ , abstract = {The gravitational potential of the Milky Way encodes information about the distribution of all matter—including dark matter—throughout the Galaxy. Gaia Data Release 3 has revealed a complex structure that necessitates flexible models of the Galactic gravitational potential. We make use of a sample of 5.6 million upper-main-sequence stars to map the full three-dimensional gravitational potential in a 1 kpc radius from the Sun using a data-driven approach called “Deep Potential.” This method makes minimal assumptions about the dynamics of the Galaxy—that the stars are a collisionless system that is statistically stationary in a rotating frame (with pattern speed to be determined). We model the distribution of stars in six-dimensional phase space using a normalizing flow and the gravitational network using a neural network. We recover a local pattern speed of Ω p = 28.2 ± 0.1 km s −1 kpc −1 , a local total matter density of ρ = 0.086 ± 0.010 M ⊙ pc −3 , and local dark matter density of ρ DM = 0.007 ± 0.011 M ⊙ pc −3 . The full three-dimensional model exhibits spatial fluctuations, which may stem from the model architecture and nonstationarity in the Milky Way.}, archive = {J_ApJ}, author = {Taavet Kalda and Gregory M. Green}, doi = {10.3847/1538-4357/adf8ea}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {84}, shortjournal = {The Astrophys. J.}, title = {Deep potential: Recovering the gravitational potential and local pattern speed in the solar neighborhood with GDR3 using normalizing flows}, volume = {992}, year = {2025}, }
• (2025). Petrogenesis of lunar farside highland lithologies: Implications for lunar crust formation. ApJ, 992(1), 83. (www)

  @article{ , abstract = {The lunar soil samples collected by the Chang’e-6 (CE-6) mission provide a unique opportunity to study the composition and formation of the lunar crust on the farside of the Moon. This study examines the petrogenesis of anorthosites and noritic anorthosites from the lunar farside using samples collected by the CE-6 mission. The analysis reveals that the ferroan anorthosite (FAN) clasts display plagioclase An# and mafic mineral Mg# within the range of Apollo FANs, highlighting the compositional similarity between the lunar nearside and farside. The identification of FANs on the farside underscores the global nature of these lithologies, indicating that the early lunar crust formation processes were not confined to the nearside but were widespread across the Moon. The noritic anorthosite clast shows characteristics consistent with KREEP-free/poor Mg-suite rocks. This finding supports the idea that both the nearside and farside experienced similar magmatic processes, challenging the simplistic hemispheric dichotomy models. The study emphasizes significant lithological variations at local scale and the need for further sample-return missions to elucidate the compositional diversity and formation history of the lunar crust.}, archive = {J_ApJ}, author = {Jiaqi Zheng and Qi He and Zaicong Wang and Jun Huang and J. F. Pernet-Fisher and Yiheng Li and Xu Chen and Keqing Zong and Ioannis Baziotis and Long Xiao and Zhenbing She}, doi = {10.3847/1538-4357/adfcd0}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {83}, shortjournal = {The Astrophys. J.}, title = {Petrogenesis of lunar farside highland lithologies: Implications for lunar crust formation}, volume = {992}, year = {2025}, }
• (2025). Magnetic reconnection as a potential driver of X-ray variability in active galactic nuclei. ApJ, 992(1), 82. (www)

  @article{ , abstract = {We present a systematic analysis on the X-ray variability in 13 bright quasars at z > 4.5, combining recent Swift observations from 2021 to 2023 and archival multiepoch observations. Upper limits of the luminosity measurements were included in the analysis by using the Kaplan–Meier estimator method. It is found that the high-redshift quasars exhibit X-ray variability on both short-term (hours to days) and intermediate-term (weeks to months) timescales, with short-term variability dominating the overall variation. A linear correlation exists between the global mean ( μ L 2 − 10 k e V ) and standard deviation ( σ L 2 − 10 k e V ) of X-ray luminosities, which is independent of the X-ray photon index and optical-to-X-ray spectral slope. The localized stochastic magnetic reconnection mechanism is strongly favored, which can naturally lead to a scale-invariant power-law energy distribution and satisfactorily explain the correlation. The σ – μ correlation parallels the well-documented rms–flux relation of low-redshift active galactic nuclei (AGNs), implying that the magnetic reconnection mechanism could drive short-timescale X-ray variability in both high- and low-redshift AGNs. The highest-redshift quasar in our sample, J142952+544717 ( z = 6.18), shows a luminosity distribution extending to 10 47 erg s −1 with a not conspicuous median luminosity. On the other hand, J143023+420436 ( z = 4.7), which hosts the most relativistic jet among known high-redshift blazars, is dominated in the high-luminosity regime (10 47 erg s −1 ), making it an ideal target for multiwavelength follow-up observations. J090630+693030 is found to have a rest-frame period of 182.46 days, and J143023+420436 has a period of 16.89 days; both could be explained by the global evolution of plasmoid chains, in which magnetic islands formed during reconnection may merge successively.}, archive = {J_ApJ}, author = {Chen-Ran Hu and Yong-Feng Huang and Lang Cui and Hanle Zhang and Jiang-Tao Li and Li Ji and Jin-Jun Geng and Orkash Amat and Fan Xu and Chen Du and Wen-Long Zhang and Ze-Cheng Zou and Xiao-Fei Dong and Chen Deng and Pengfei Jiang and Jie Liao}, doi = {10.3847/1538-4357/adfed2}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {82}, shortjournal = {The Astrophys. J.}, title = {Magnetic reconnection as a potential driver of X-ray variability in active galactic nuclei}, volume = {992}, year = {2025}, }
• (2025). Particle acceleration and transport in the large-scale current sheet under an erupting magnetic flux rope. ApJ, 992(1), 81. (www)

  @article{ , abstract = {We investigate the acceleration and transport of electrons in the highly fine-structured current sheet that develops during magnetic flux rope (MFR) eruptions. Our work combines ultraresolved magnetohydrodynamic (MHD) simulations of MFR eruption, with test-particle studies performed using the guiding center approximation. Our grid-adaptive, fully 3D, high-resolution MHD simulations model MFR eruptions that form complex current-sheet topologies, serving as background electromagnetic fields for particle acceleration. Within the current sheet, tearing-mode instabilities give rise to mini flux ropes. Electrons become temporarily trapped within these elongated structures, undergoing acceleration and transport processes that significantly differ from those observed in 2D or 2.5D simulations. Our findings reveal that these fine-scale structures act as efficient particle accelerators, surpassing the acceleration efficiency of single X-line reconnection events, and are capable of energizing electrons to energies exceeding 100 keV. High-energy electrons accelerated in different mini flux ropes follow distinct trajectories, due to spatially varying magnetic field connectivity, ultimately precipitating onto opposite sides of flare ribbons. Remarkably, double electron sources at the flare ribbons originate from different small-flux-rope acceleration regions, rather than from the same reconnecting field line, as previously suggested. Distinct small flux ropes possess opposite magnetic helicity, to accelerate electrons to source regions with different magnetic polarities, establishing a novel conjugate double-source configuration. Furthermore, electrons escaping from the lower regions exhibit a broken-power-law energy spectrum. This spectral break arises from electrons accelerated in disparate mini flux ropes, each exhibiting magnetic reconnection rates and acceleration efficiencies, which reflect the varying local reconnection conditions.}, archive = {J_ApJ}, author = {H. Wu and Y. Guo and R. Keppens and C. Xia and Y. Su and X. L. Kong and M. D. Ding}, doi = {10.3847/1538-4357/adfed4}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {81}, shortjournal = {The Astrophys. J.}, title = {Particle acceleration and transport in the large-scale current sheet under an erupting magnetic flux rope}, volume = {992}, year = {2025}, }
• (2025). Particle-in-cell simulation of current-driven solar type III radiation and whistler waves in a core–strahl plasma: Relevance to PSP and other space observations. ApJ, 992(1), 80. (www)

  @article{ , abstract = {The aim of this paper is to demonstrate that electron current oscillations may generate electromagnetic waves as type III radiation and whistler waves without the involvement of the classical plasma emission via the coalescence of waves. Particle-in-cell (PIC) simulation results of a core–strahl plasma without initial current compensation are presented, which describe the conversion of current-driven Langmuir oscillations/waves into type III radiation, whereby simultaneously whistler waves are excited. In contrast to the classical approach of V. L. Ginzburg & V. V. Zhelezniakov, after which beam-excited Langmuir waves in a two-step process are converted into electromagnetic radiation, any instability is suppressed by selecting a low strahl velocity. Rather, electric field oscillations at the electron plasma frequency are triggered by the initially noncompensated current of the strahl. The arising electromagnetic fields exhibit amplitude oscillations, which are caused by the superposition of the two wave modes of mixed polarization at the point of mode coupling. This basic mechanism of wave generation and transformation has already been described in earlier papers using simple fluid models. It is also the topic of the companion paper. Besides the fundamental electromagnetic radiation, the second harmonic of nearly the same intensity has been obtained, which is an indication of its generation by nonlinear currents. Measurements of Langmuir waves, type III radiation, and whistler waves on board various satellites in the solar wind, in particular Parker Solar Probe observations, are analyzed in the light of our results. Interpretations of earlier PIC simulations are critically reviewed.}, archive = {J_ApJ}, author = {Konrad Sauer and Kaijun Liu}, doi = {10.3847/1538-4357/adff53}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {80}, shortjournal = {The Astrophys. J.}, title = {Particle-in-cell simulation of current-driven solar type III radiation and whistler waves in a core–strahl plasma: Relevance to PSP and other space observations}, volume = {992}, year = {2025}, }
• (2025). Decoding the single-peaked h i spectra of low redshift poststarburst galaxies. ApJ, 992(1), 79. (www)

  @article{ , abstract = {Recent observations with the Five-hundred-meter Aperture Spherical Telescope have revealed abundant reservoirs of neutral hydrogen (H I ) in low-redshift poststarburst galaxies (PSBs), raising the question of why star formation ceases rapidly in these systems. In this study, we present a detailed analysis of the shape of the integrated H I spectra of 67 PSBs. We find that PSBs exhibit significantly higher H I spectral concentration values ( K ) compared to a matched sample from xGASS, and are more comparable to those of starburst galaxies. By extending our analysis to spatially resolved H I data from THINGS and Atlas 3D , we show that both centrally concentrated H I distributions and dynamically unsettled H I can effectively increase K , while nonaxisymmetric structures only contribute to the scatter of the K distribution. Distinguishing between central concentration and dynamically unsettled gas as the origin of high K can be achieved by measuring the spectral asymmetry ( A F ), making the K – A F plane a powerful diagnostic tool for identifying galaxies with unsettled H I using integrated spectra alone. Based on their location in the K – A F plane, we find that most PSBs are not dominated by unsettled H I , but rather exhibit elevated central gas concentration. Both modes of gas redistribution in PSBs may eventually contribute to their quenching.}, archive = {J_ApJ}, author = {Qifeng Huang and Jing Wang and Sara L. Ellison and Zezhong Liang and Xuchen Lin and Dong Yang}, doi = {10.3847/1538-4357/ae0040}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {79}, shortjournal = {The Astrophys. J.}, title = {Decoding the single-peaked h i spectra of low redshift poststarburst galaxies}, volume = {992}, year = {2025}, }
• (2025). A reidentification of six candidate gravitationally lensed gamma-ray bursts. ApJ, 992(1), 78. (www)

  @article{ , abstract = {The gravitational lensing effect of gamma-ray bursts (GRBs) holds significant and diverse applications in the field of astronomy. Nevertheless, the identification of millilensing events in GRBs presents substantial challenges. We re-evaluate the gravitational lensing candidacy of six previously proposed GRBs (GRB 081122A, GRB 081126A, GRB 090717A, GRB 110517B, GRB 200716C, and GRB 210812A) using a comprehensive set of temporal and spectral diagnostics. These include χ 2 light-curve similarity tests, photon-count-based hardness ratio (HR count ) comparisons, T 90 duration measurements, spectral lag, Norris pulse-shape fitting, and both time-resolved and time-integrated spectral analyses. We propose an evaluation framework in which any single test that reveals a statistically significant inconsistency between the two pulses is sufficient to reject the lensing hypothesis for that burst. Although certain diagnostics, such as T 90 and parametric model fits, have known limitations, they are applied and interpreted in conjunction with the more robust, model-independent χ 2 and HR count tests. For all six GRBs, at least one diagnostic shows a significant discrepancy, leading us to conclude that none are consistent with a gravitational lensing interpretation.}, archive = {J_ApJ}, author = {Yu Zhao and Zhao-Yang Peng and Jia-Ming Chen and Yue Yin and Ting Li}, doi = {10.3847/1538-4357/ae00c6}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {78}, shortjournal = {The Astrophys. J.}, title = {A reidentification of six candidate gravitationally lensed gamma-ray bursts}, volume = {992}, year = {2025}, }
• (2025). Effects of nonresonant instability and magnetic reconnection on ion heating and acceleration in quasi-parallel shock waves. ApJ, 992(1), 77. (www)

  @article{ , abstract = {To understand the ion injection for diffusive shock acceleration in space and astrophysical shock waves, such as in planetary bow shocks and supernova remnant shocks, ion heating and acceleration in high-Alfvén-Mach-number ( M A ) quasi-parallel shock waves are studied by means of full particle-in-cell (PIC) simulations and theory. We perform 2D and 3D PIC simulations in the regime of M A ≥ 10, where shock-driven turbulence contains a number of current sheets and magnetic reconnection sites. The nonresonant ion–ion beam mode grows in the shock transition region, which creates current sheets, and some of them drive magnetic reconnection. The ion temperature in magnetic islands produced by ion-coupled reconnection becomes significantly higher than those in the surrounding regions. This temperature enhancement is due to two physical reasons: the reduction of the number density of the incident ions in the nonresonant wave, and the energization and heating in the magnetic islands. Ions that enter magnetic islands are energized by the Hall electric field pointing toward the island center. Ions are also energized by the motional electric field produced in the outer regions of the islands and the current sheets. The energy increase rate of ions by these energization mechanisms is much larger than that of the conventional shock drift acceleration. These energetic ions are unmagnetized, and they escape from the shock transition region toward the upstream region; therefore, ions in shocks with reconnecting current sheets can be injected into diffusive shock acceleration more efficiently than those in laminar shock waves.}, archive = {J_ApJ}, author = {N. Bessho and J. Ng and L.-J. Chen and M. Hesse and L. B. Wilson and J. E. Stawarz}, doi = {10.3847/1538-4357/ae00c9}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {77}, shortjournal = {The Astrophys. J.}, title = {Effects of nonresonant instability and magnetic reconnection on ion heating and acceleration in quasi-parallel shock waves}, volume = {992}, year = {2025}, }
• (2025). A search for meteoroid streams and their sources in the near-sun zodiacal dust cloud. ApJ, 992(1), 76. (www)

  @article{ , abstract = {The structure and dynamics of the zodiacal cloud close to the Sun may be significantly influenced by the interaction between a background quasihomogeneous zodiacal cloud and discrete meteoroid streams associated with small bodies like comets and asteroids. The extent of this influence depends upon how many such streams exist and the mechanisms by which they modify the near-Sun zodiacal cloud. This study compares in situ dust detection data in near-Sun solar wind against predictions made by a simplified zodiacal dust cloud model to search for small-scale meteoroid stream structures. A strong localized departure from the model is found. A small number of asteroids and comets have been identified that have orbits appropriate to produce the observed departure from the model through either direct meteoroid stream detection or through enhanced β -meteoroid production. These observations suggest that discrete meteoroid streams may be common in the inner zodiacal cloud and therefore may be important for its structure and dynamics.}, archive = {J_ApJ}, author = {David M. Malaspina and Jamey R. Szalay and Avery Mazurkiewicz and Delaney Lee-Bellows and Margaret E. Landis}, doi = {10.3847/1538-4357/ae0184}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {76}, shortjournal = {The Astrophys. J.}, title = {A search for meteoroid streams and their sources in the near-sun zodiacal dust cloud}, volume = {992}, year = {2025}, }
• (2025). Lithium abundances of main-sequence stars in the old open cluster NGC 188: Probes of stellar evolution beyond the solar age∗. ApJ, 992(1), 75. (www)

  @article{ , abstract = {We present lithium abundances for 119 main-sequence stars in the old open cluster NGC 188 (age = 6.3 Gyr), using high-resolution, high signal-to-noise ratio spectra from WIYN/Hydra. We observe the stars over multiple nights and measure radial velocities for each night, which we combine with Gaia proper motions to identify multiplicity and cluster membership. We identify 95 single members, 14 binary members, 9 members with uncertain multiplicity, and 1 single likely member. We determine effective temperatures using empirical color–temperature relations, surface gravities from isochrones, and microturbulence from empirical relations for main-sequence stars. Our sample includes G dwarfs with temperatures between 6000 and 5300 K, which expands significantly on earlier observations. We find that lithium abundances in NGC 188 are lower than predictions from standard stellar evolution theory. As expected, stars in NGC 188 are more lithium-depleted than those in the younger Hyades and Praesepe clusters (650 Myr). However, their abundances are higher, or at least comparable, to those in the slightly younger cluster M67 (4 Gyr), challenging the idea that older stars have lower lithium than younger ones. Lithium depletion may depend on factors beyond age and mass, such as metallicity.}, archive = {J_ApJ}, author = {Qinghui Sun and Constantine P. Deliyannis and Bruce A. Twarog and Barbara J. Anthony-Twarog}, doi = {10.3847/1538-4357/ae032a}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {75}, shortjournal = {The Astrophys. J.}, title = {Lithium abundances of main-sequence stars in the old open cluster NGC 188: Probes of stellar evolution beyond the solar age∗}, volume = {992}, year = {2025}, }
• (2025). The influence of central body tides on catastrophic disruptions of close-in planetary satellites. ApJ, 992(1), 74. (www)

  @article{ , abstract = {We model the outcomes of catastrophic disruptions on small, gravity-dominated natural satellites, accounting for the tidal potential of the central body, which is neglected in classical disruption scaling laws. We introduce the concept of {Q}_{\,\rm{TD}\,}^{\star } , the specific energy required to disperse half of the total mass involved in a collision, accounting for the tidal potential of a central body. We derive a simple scaling relation for {Q}_{\,\rm{TD}\,}^{\star } and demonstrate that for close-in planetary or asteroidal satellites, the tides from the central body can significantly reduce their catastrophic disruption threshold. We show that many satellites in the solar system are in such a regime, where their disruption threshold should be much lower than that predicted by classical scaling laws that neglect tidal effects. Some notable examples include Mars’s Phobos, Jupiter’s Metis and Adrastea, Saturn’s ring moons, Uranus’s Ophelia, and Neptune’s Naiad and Thalassa, among others. We argue that traditional impact scaling laws should be modified to account for tides when modeling the formation and evolution of these close-in satellites. Our derivation for {Q}_{\,\rm{TD}\,}^{\star } can easily be used in existing N -body and collisional evolution codes.}, archive = {J_ApJ}, author = {Harrison Agrusa and Patrick Michel}, doi = {10.3847/1538-4357/ae04e4}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {74}, shortjournal = {The Astrophys. J.}, title = {The influence of central body tides on catastrophic disruptions of close-in planetary satellites}, volume = {992}, year = {2025}, }
• (2025). Stringent constraints on the nuclear matter equation of state from heavy nuclei and neutron star properties with a multi-iteration bayesian statistical analysis. ApJ, 992(1), 73. (www)

  @article{ , abstract = {The equation of state (EoS) of dense nuclear matter, particularly the symmetry energy that characterizes its isospin dependence, is of fundamental importance in neutron star (NS) physics and nuclear physics. Apart from the extensively used multimessenger astrophysics information, we introduce three new constraints to tighten the EoS at intermediate densities: (i) the absent direct Urca process in the 1.5 M ⊙ NS; (ii) the symmetry energy (coefficient) a sym of 208 Pb; (iii) the strong linear correlation between the slope parameter L of symmetry energy E sym ( ρ ) at saturation density ρ 0 and E sym ( ρ 0 ) − a sym . These constraints turn out to be highly effective for symmetry energy. As an alternative strategy, we employ the Bayesian statistical method with a multi-iteration procedure to ensure that the resulting posterior probability distribution is free of the initial prior distribution as far as possible. The most probable result of symmetry energy exhibits a soft behavior up to ∼2.5 ρ 0 , and then it rises rapidly as the density increases. On the one hand, our results allow one to explore a series of topics in NS physics. For instance, the radius and tidal deformability for a 1.4 M ⊙ NS are {R}_{1.4}=12.4{6}_{-0.80}^{+0.22}\,{\rm{km}} and {{\rm{\Lambda }}}_{1.4}=47{8}_{-183}^{+90} . The vast majority of NSs are unlikely to contain deconfined quark matter in their cores. On the other hand, almost all the widely used nuclear many-body approaches fail to reproduce such a trend of symmetry energy, and hence our results serve as an important calibration for nuclear force and nuclear many-body approaches.}, archive = {J_ApJ}, author = {Xue-Ying Jing and Jian-Min Dong}, doi = {10.3847/1538-4357/ae0627}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {73}, shortjournal = {The Astrophys. J.}, title = {Stringent constraints on the nuclear matter equation of state from heavy nuclei and neutron star properties with a multi-iteration bayesian statistical analysis}, volume = {992}, year = {2025}, }
• (2025). The M- and X-class white-light flares in super active region NOAA 13664/13697 observed by ASO-S/LST/WST. ApJ, 992(1), 72. (www)

  @article{ , abstract = {Solar white-light flares (WLFs) have been observed since 1859, but their occurrence rate is not yet fully understood. The physical properties of WLFs in super active regions (SARs) are also well worth investigating. With full-disk images at 3600 Å (in the Balmer continuum) from the White-light Solar Telescope on board the Advanced Space-based Solar Observatory, we here study the M- and X-class WLFs occurring in SAR NOAA 13664/13697 (a same region in two solar Carrington rotations) during 2024 May/June. In all, 48 WLFs at 3600 Å are identified from 89 available samples with an occurrence rate of 53.9%, which is much higher than that (23.9%) of a long-term-continuous data set from 2022 October to 2023 May in our previous work. In particular, with an additional sample of over 730 M- and X-class flares from 2022 October to 2024 June, we find that the occurrence rate of WLFs shows a good correlation with the solar cycle represented by sunspot counts. As regards the properties of the emission at 3600 Å, the WLFs in SAR NOAA 13664/13697 have some different characteristics, say, a longer duration but a weaker relative enhancement and a smaller brightening area compared with the previous long-term-continuous sample. We also find that for WLFs in NOAA 13664/13697 the relation between the duration and energy at 3600 Å is described by a power law with index of 0.35, which is similar to the results found for superflares in Sun-like stars. All these help us understand the solar WLFs in SARs and also provide important insights into the superflares on Sun-like stars.}, archive = {J_ApJ}, author = {Zhichen Jing and Ying Li and Jingwei Li and Qiao Li}, doi = {10.3847/1538-4357/ae0708}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {72}, shortjournal = {The Astrophys. J.}, title = {The M- and X-class white-light flares in super active region NOAA 13664/13697 observed by ASO-S/LST/WST}, volume = {992}, year = {2025}, }
• (2025). Not just a dot: The complex UV morphology and underlying properties of little red dots. ApJ, 992(1), 71. (www)

  @article{ , abstract = {We analyze 99 photometrically selected Little Red Dots (LRDs) at z ≈ 4–8 in the GOODS fields, leveraging ultradeep JADES NIRCam short-wavelength (SW) data. Among the 99 selected LRDs, we examine the morphology of 30. The remaining 69 appear predominantly compact, with sizes ≲400 pc and no extended components even in stacked SW images. However, their unresolved nature may partly reflect current depth limitations, which could prevent the detection of faint diffuse components. Among the 30 morphologically analyzed LRDs, 50% show multiple associated components, while the rest exhibit highly asymmetric structures, despite appearing as single sources. This diversity in rest-frame UV morphologies may point to interactions or strong internal feedback. We find median stellar masses of {{\mathrm{log}}_{10}}\,({M}_{\star }/{M}_{\odot })=9.0{7}_{-0.08}^{+0.11} for pure stellar models with {A}_{V}\approx 1.1{6}_{-0.21}^{+0.11} mag, and {{\mathrm{log}}_{10}}\,({M}_{\star }/{M}_{\odot })=9.6{7}_{-0.27}^{+0.17} for models including active galactic nuclei (AGNs) with {A}_{V}\approx 2.7{4}_{-0.71}^{+0.55} mag, in line with recent studies suggesting higher masses and dust content for AGN-fitted LRDs. NIRSpec spectra are available for 15 sources, six of which are also in the morphological sample. Broad H α is detected in 40% (FWHM = 1200–2900 km s −1 ), and one source shows broad H β emission. Emission line ratios indicate a composite nature, consistent with both AGN and stellar processes. Altogether, these results suggest that LRDs are a mixed population, and their rest-frame UV morphology reflects this complexity. Morphological studies of larger samples could provide a new way to understand what drives their properties and evolution.}, archive = {J_ApJ}, author = {P. Rinaldi and N. Bonaventura and G. H. Rieke and S. Alberts and K. I. Caputi and W. M. Baker and S. Baum and R. Bhatawdekar and A. J. Bunker and S. Carniani and E. Curtis-Lake and F. D’Eugenio and E. Egami and Z. Ji and B. D. Johnson and K. Hainline and J. M. Helton and X. Lin and J. Lyu and Z. Ma and R. Maiolino and P. G. Pérez-González and M. Rieke and B. E. Robertson and I. Shivaei and M. Stone and Y. Sun and S. Tacchella and H. Übler and C. C. Williams and C. N. A. Willmer and C. Willott and J. Zhang and Y. Zhu}, doi = {10.3847/1538-4357/adfa10}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {71}, shortjournal = {The Astrophys. J.}, title = {Not just a dot: The complex UV morphology and underlying properties of little red dots}, volume = {992}, year = {2025}, }
• (2025). The BlueDOG at cosmic noon: A possible analog to little red dots?. ApJ, 992(1), 70. (www)

  @article{ , abstract = {We discovered a hyperluminous dust-obscured galaxy with mysterious blue-excess emission (BlueDOG) in the rest-frame UV of its spectral energy distribution (SED) from a multiwavelength survey in the AKARI Deep Field - South (ADF-S). We present the results of SED analysis with multiwavelength photometric data and spectroscopic analysis, observed with Gemini-S/GMOS, FLAMINGOS-2, to explore the origin of blue-excess emission of a hyperluminous BlueDOG, ADFS-KMTDOG-102, at z = 2.6. The SED analysis shows that this BlueDOG is a highly massive system (log M * / M ⊙ = 12.3) with substantial extinction. Additionally, the proportion of the old stellar population exceeds that of the young stellar population, which suggests stellar evolution cumulated from the early Universe. The mass of the supermassive black hole estimated using the extinction-corrected broad H α emission line yields log M BH / M ⊙ = 10.2. We discuss the similarity between the BlueDOG and “Little Red Dots” (LRDs), recently discovered with the James Webb Space Telescope, showing SED shapes remarkably similar to those of LRDs. The UV emission line ratios indicate that the emission lines are primarily powered by the central active galactic nuclei (AGN). In contrast, the origin of the blue-excess UV continuum remains ambiguous, since both recent star formation and AGN-induced scattered light are viable explanations, based on the results from the SED fitting and scattered light modeling.}, archive = {J_ApJ}, author = {Seongjae Kim and Woong-Seob Jeong and Minjin Kim and Hyunsung D. Jun and Yujin Yang and Takao Nakagawa}, doi = {10.3847/1538-4357/adff59}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {70}, shortjournal = {The Astrophys. J.}, title = {The BlueDOG at cosmic noon: A possible analog to little red dots?}, volume = {992}, year = {2025}, }
• (2025). Theoretical perspective on the occurrence of electrostatic solitary waves and double layers in ganymede’s wake region. ApJ, 992(1), 69. (www)

  @article{ , abstract = {The first close flyby of Ganymede by Juno on 2021 June 7 provided a unique opportunity to visit the previously unexplored wake and magnetopause regions. During the flyby, the Juno Waves instrument recorded traces of the existence of electrostatic solitary waves (ESWs) in the wake and magnetopause boundary. The flyby detected the presence of H 2 + and H 3 + ions in Ganymede’s wake for the first time, indicating that the wake is dominated by water products from the surface of Ganymede. The conditions for the occurrence of ESWs and double layers in the wake region and the associated existence domains (in parameter space) are explored in this paper. A magnetized fluid plasma is introduced to model Ganymede’s wake conditions, comprising of warm H + , O + , and H 3 + ions and an electron beam, in addition to a non-Maxwellian background of suprathermal electrons. We have explored in particular the role of the third ion component H 3 + on the properties of ESWs. Different acoustic modes are predicted and used as basis for our analysis, namely identified as one slow and two fast ion-acoustic modes and a higher-frequency electron-acoustic mode. Nonlinear analysis shows that the model may support the existence of positive and negative potential ion-acoustic solitons and double layers depending on the number density and on the temperature of H 3 + ions. The theoretical prediction is correlated with observed ESWs in Ganymede’s wake.}, archive = {J_ApJ}, author = {R. Rubia and M. B. Dhanya and Kuldeep Singh and Ioannis Kourakis}, doi = {10.3847/1538-4357/adff57}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {69}, shortjournal = {The Astrophys. J.}, title = {Theoretical perspective on the occurrence of electrostatic solitary waves and double layers in ganymede’s wake region}, volume = {992}, year = {2025}, }
• (2025). Spectral evolution of rotating population III stars. ApJ, 992(1), 68. (www)

  @article{ , abstract = {Population III (Pop III) stars, the first generation of stars formed from primordial gas, played a fundamental role in shaping the early Universe through their influence on cosmic reionization, early chemical enrichment, and the formation of the first galaxies. However, to date, they have eluded direct detection due to their short lifetimes and high redshifts. The launch of the James Webb Space Telescope (JWST) has revolutionized observational capabilities, providing the opportunity to detect Pop III stars via caustic lensing, where strong gravitational lensing magnifies individual stars to observable levels. This prospect makes it compelling to develop accurate models for their spectral characteristics to distinguish them from other stellar populations. Previous studies have focused on computing the spectral properties of nonrotating, zero-age main-sequence (ZAMS) Pop III stars. In this work, we expand upon these efforts by incorporating the effects of stellar rotation and post-ZAMS evolution into spectral calculations. We use the JWST bands and magnitude limits to identify the optimal observing conditions, both for isolated stars, as well as for small star clusters. We find that, while rotation does not appreciably change the observability at ZAMS, the subsequent evolution can significantly brighten the stars, making the most massive ones potentially visible with only moderate lensing.}, archive = {J_ApJ}, author = {Jake B. Hassan and Rosalba Perna and Matteo Cantiello and Tyler M. Parsotan and Davide Lazzati and Nathan Walker}, doi = {10.3847/1538-4357/ae0032}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {68}, shortjournal = {The Astrophys. J.}, title = {Spectral evolution of rotating population III stars}, volume = {992}, year = {2025}, }
• (2025). Impact of cosmic ray-driven outflows on lyα emission in cosmological simulations. ApJ, 992(1), 67. (www)

  @article{ , abstract = {Cosmic ray (CR) feedback has been proposed as a powerful mechanism for driving warm gas outflows in galaxies. We use cosmological magnetohydrodynamic simulations to investigate the impact of CR feedback on neutral hydrogen (H i ) in a 10 11 M ⊙ dark matter halo at 2 < z < 4. To this end, we postprocess the simulations with ionizing radiative transfer and perform Monte Carlo Lyman- α (Ly α ) transfer calculations. CR feedback reduces H i column densities around young stars, thereby allowing more Ly α photons to escape and consequently offering a better match to the Ly α luminosities of observed Ly α emitters. Although galaxies with CR-driven outflows have more extended H i in the circumgalactic medium, two Ly α line properties sensitive to optical depth and gas kinematic—the location of the red peak relative to the Ly α line center in velocity space ( v red ) and relative strength of the blue-to-red peaks ( B / R )—cannot distinguish between the CR-driven and non-CR simulations. This is because Ly α photons propagate preferentially along low H i density channels created by the ionizing radiation, thereby limiting the scattering with volume-filling H i . In contrast, the observed low flux ratios between the valley and peak and the surface brightness profiles are better reproduced in the model with CR-driven outflows because the Ly α photons interact more before escaping, rather than being destroyed by dust as is the case in the non-CR simulation. We discuss the potential cause of the paucity of sightlines in simulations that exhibit prominent red peaks and large v red , which may require the presence of more volume-filling H i .}, archive = {J_ApJ}, author = {Taysun Kimm and Julien Devriendt and Francisco Rodríguez Montero and Adrianne Slyz and Jérémy Blaizot and Harley Katz and Beomchan Koh and Hyunmi Song}, doi = {10.3847/1538-4357/ae00c5}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {67}, shortjournal = {The Astrophys. J.}, title = {Impact of cosmic ray-driven outflows on lyα emission in cosmological simulations}, volume = {992}, year = {2025}, }
• (2025). X-ray and radio polarimetry of the neutron star low-mass X-ray binary GX 13+1. ApJ, 992(1), 66. (www)

  @article{ , abstract = {We report the X-ray and radio polarization study of the neutron star low-mass X-ray binary (LMXB) GX 13+1 using the Imaging X-ray Polarimetry Explorer (IXPE) and Very Large Array. Simultaneous Neutron Star Interior Composition Explorer observations show that the source was in parts of the Z state during our IXPE observations, exhibiting moderate changes in the hardness–intensity diagram. The source exhibits X-ray dips in the light curve along with hints of polarization swings between the dip and nondip states. The X-ray spectropolarimetry results suggest a source geometry comprising an accretion disk component representing the softer disk emission, along with a blackbody representing the harder emission from the boundary layer or a spreading layer. We investigate the geometry of GX 13+1 by considering our X-ray and radio polarization findings.}, archive = {J_ApJ}, author = {Unnati Kashyap and Thomas J. Maccarone and Eliot C. Pattie and Mason Ng and Swati Ravi and Herman L. Marshall}, doi = {10.3847/1538-4357/adf968}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {66}, shortjournal = {The Astrophys. J.}, title = {X-ray and radio polarimetry of the neutron star low-mass X-ray binary GX 13+1}, volume = {992}, year = {2025}, }
• (2025). Cosmic infrared background tomography and a census of cosmic dust and star formation. ApJ, 992(1), 65. (www)

  @article{ , abstract = {The cosmic far-infrared background (CIB) encodes dust emission from all galaxies and carries valuable information on structure formation, star formation, and chemical enrichment across cosmic time. However, its redshift-dependent spectrum remains poorly constrained due to line-of-sight projection effects. We address this by cross-correlating 11 far-infrared intensity maps spanning a 50-fold frequency range from Planck, Herschel, and Infrared Astronomical Satellite, with spectroscopic galaxies and quasars from Sloan Digital Sky Survey I–IV tomographically. We mitigate foregrounds using a CIB-free Milky Way dust map. These cross-correlation amplitudes on two-halo scales trace bias-weighted CIB redshift distributions and collectively yield a 60 σ detection of the evolving CIB spectrum, sampled across hundreds of rest-frame frequencies over 0 < z < 4. We break the bias–intensity degeneracy by adding monopole information from FIRAS+Planck. The recovered spectrum reveals a dust temperature distribution that is broad, spanning the full range of host environments, and moderately evolving. Using low-frequency CIB amplitudes, we constrain cosmic dust density, Ω dust , which peaks at z = 1–1.5 and declines threefold to the present. Our broad spectral coverage enables a determination of the total infrared luminosity density to 0.04 dex statistical precision, tracing star formation history with negligible cosmic variance across 90% of cosmic time. We find that cosmic star formation is 80% dust-obscured at z = 0 and 60% at z = 4. Our results, based on intensity mapping, are complete, requiring no extrapolation to faint galaxies or low-surface-brightness components. We release our tomographic CIB spectrum and redshift distributions as a public resource for future studies of the CIB, both as a cosmological matter tracer and cosmic microwave background foreground.}, archive = {J_ApJ}, author = {Yi-Kuan Chiang and Ryu Makiya and Brice Ménard}, doi = {10.3847/1538-4357/adfb6a}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {65}, shortjournal = {The Astrophys. J.}, title = {Cosmic infrared background tomography and a census of cosmic dust and star formation}, volume = {992}, year = {2025}, }
• (2025). The study of the circumnuclear environment of accreting supermassive black holes with realistic X-ray spectral models. ApJ, 992(1), 64. (www)

  @article{ , abstract = {X-ray spectral modeling is a powerful tool for studying the immediate environment of accreting objects, including supermassive black holes. Several models, either phenomenological or physically driven, have been developed over the past decade to study X-ray spectra, delivering important insights into the properties of circumnuclear material of active galactic nuclei. Despite the fact that these models are able to reproduce the data well, they often lack realistic geometries and most of them consist of simplified configurations such as a slab or a torus. We use the ray-tracing code R efle X to generate new spectral models that cover a wide energy range in the X-ray band, adopting a realistic configuration for the surrounding material. We introduce two new table models that are publicly available: (1) the RXToPo model, which features an X-ray source along with a dusty torus and a polar hollow cone; and (2) the RXagn1 model, which also includes, besides the torus and polar cone, the accretion disk and the broad line region. Both models were applied to the X-ray spectrum of NGC 424, demonstrating their potential to study sources whose X-ray emission is dominated by reprocessed radiation.}, archive = {J_ApJ}, author = {G. Dimopoulos and C. Ricci and S. Paltani}, doi = {10.3847/1538-4357/adfd52}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {64}, shortjournal = {The Astrophys. J.}, title = {The study of the circumnuclear environment of accreting supermassive black holes with realistic X-ray spectral models}, volume = {992}, year = {2025}, }
• (2025). The z ≳ 9 galaxy UV luminosity function from the JWST advanced deep extragalactic survey: Insights into early galaxy evolution and reionization. ApJ, 992(1), 63. (www)

  @article{ , abstract = {The high-redshift UV luminosity function provides important insights into the evolution of early galaxies. JWST has revealed an unexpectedly large population of bright ( M UV ≲ −20) galaxies at z ≳ 10, implying fundamental changes in the star-forming properties of galaxies at increasingly early times. However, constraining the fainter population ( M UV ≳ −18) has been more challenging. In this work, we present the z ≳ 9 UV luminosity function from the JWST Advanced Deep Extragalactic Survey. We calculate the UV luminosity function from several hundred z ≳ 9 galaxy candidates that reach UV luminosities of M UV ∼ −17 in redshift bins of z ∼ 8.5–12 (309 candidates) and z ∼ 12–16 (63 candidates). We search for candidates at z ∼ 16–22.5 and find none. We also estimate the z ∼ 14–16 luminosity function from the z ≥ 14 subset of the z ∼ 12–16 sample. Consistent with other measurements, we find an excess of bright galaxies that is in tension with many theoretical models, especially at z ≳ 12. However, we also find high number densities at −18 ≲ M UV ≲ −17, suggesting that there is a larger population of faint galaxies than expected, as well as bright ones. From our parametric fits for the luminosity function, we find steep faint-end slopes of −2.5 ≲ α ≲ −2.3, suggesting a large population of faint ( M UV ≳ −17) galaxies. Combined, the high normalization and steep faint-end slope of the luminosity function could imply that the reionization process is appreciably underway as early as z = 10.}, archive = {J_ApJ}, author = {Lily Whitler and Daniel P. Stark and Michael W. Topping and Brant Robertson and Marcia Rieke and Kevin N. Hainline and Ryan Endsley and Zuyi Chen and William M. Baker and Rachana Bhatawdekar and Andrew J. Bunker and Stefano Carniani and Stéphane Charlot and Jacopo Chevallard and Emma Curtis-Lake and Eiichi Egami and Daniel J. Eisenstein and Jakob M. Helton and Zhiyuan Ji and Benjamin D. Johnson and Pablo G. Pérez-González and Pierluigi Rinaldi and Sandro Tacchella and Christina C. Williams and Christopher N. A. Willmer and Chris Willott and Joris Witstok}, doi = {10.3847/1538-4357/adfddc}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {63}, shortjournal = {The Astrophys. J.}, title = {The z ≳ 9 galaxy UV luminosity function from the JWST advanced deep extragalactic survey: Insights into early galaxy evolution and reionization}, volume = {992}, year = {2025}, }
• (2025). Electron–Ion equilibration in the merging galaxy cluster a665. ApJ, 992(1), 62. (www)

  @article{ , abstract = {Galaxy cluster mergers drive powerful shock fronts that heat the intracluster medium (ICM) and accelerate particles, redistributing the energy in a merger. A665 is one of only a few clusters with such a powerful shock ( { \mathcal M }\sim 3), and it provides a unique opportunity to study the thermalization timescale of the ICM, particularly the electron–ion equilibration timescale. Understanding this timescale is crucial for determining how the energy from the merger is distributed between thermal and nonthermal particle populations. Using ∼200 ks of NuSTAR observations, we measure the temperature distribution across the shock to distinguish between two heating models: (1) an instant collisionless model, where ions and electrons are immediately heated at the shock front; and (2) a collisional model, where electrons are initially adiabatically compressed at the shock and subsequently equilibrate with the ions over ∼100 Myr. Our measurements favor the delayed-equilibration model, suggesting that electrons do not immediately reach thermal equilibrium with the ions at the shock front and instead equilibrate over t eq = (4.0 ± 3.4) × 10 8 yr. Additionally, our temperature measurements indicate that the Mach number may be lower than previously estimated ( { \mathcal M }=2.8\pm 0.7 ), suggesting that the shock strength has been overestimated in past studies. These results add to our understanding of the microphysics governing how thermal energy is distributed in diffuse plasmas like the ICM, with implications for galaxy cluster evolution, large-scale structure formation, and cosmology.}, archive = {J_ApJ}, author = {Christian T. Norseth and Daniel R. Wik and Craig L. Sarazin and Ming Sun and Fabio Gastaldello}, doi = {10.3847/1538-4357/adfe6b}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {62}, shortjournal = {The Astrophys. J.}, title = {Electron–Ion equilibration in the merging galaxy cluster a665}, volume = {992}, year = {2025}, }
• (2025). Shedding light on the solar dynamo using data-driven bayesian parameter inference. ApJ, 992(1), 61. (www)

  @article{ , abstract = {We use a zero-dimensional stochastic dynamo model describing the coupled oscillatory behavior of the toroidal and poloidal components of the solar magnetic field. The model includes a time delay, arising from the assumption that the two field components are generated in spatially segregated locations, and a quenching of the α -effect for amplitudes of the toroidal magnetic field outside a range defined by a lower and an upper threshold. We apply two distinct simulation-based Bayesian inference methods to calibrate the model parameters. The first approach employs a Simulated Annealing Approximate Bayesian Computation algorithm, based on the comparison of relevant features extracted from observed data with their counterparts from simulated data. The second one leverages a sequential neural posterior density estimation method known as Automatic Posterior Transformation. The inference was carried out using two different data sets: the observed sunspot record and a recent millennial solar activity reconstruction based on 14 C cosmogenic radionuclides from tree rings. The different methods and data sets produce remarkably consistent posterior distributions for the model parameters. Bayesian inference results corroborate the hypothesis presented in a previous publication that the solar dynamo might be operating close to a critical bifurcation point characterized by the coexistence of two modes akin to normal and Grand Minima regimes. We show that the calibrated dynamo model, despite its simplicity, can be used to make predictions about solar cycles.}, archive = {J_ApJ}, author = {Simone Ulzega and Jürg Beer and Antonio Ferriz-Mas and Simon Dirmeier and Carlo Albert}, doi = {10.3847/1538-4357/adfec3}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {61}, shortjournal = {The Astrophys. J.}, title = {Shedding light on the solar dynamo using data-driven bayesian parameter inference}, volume = {992}, year = {2025}, }
• (2025). Characterizing close binary supermassive black holes in blazars 3C 273, 3C 454.3, s0528+134, and AO 0235+164: Insights from multifrequency radio monitoring and gravitational-wave prospects. ApJ, 992(1), 60. (www)

  @article{ , abstract = {We present new constraints on the physical properties of close binary supermassive black holes (SMBHs) in the active galactic nuclei 3C 273, 3C 454.3, S0528+134, and AO 0235+164 based on long-term, multifrequency radio monitoring. By applying a combined time-series analysis using Fourier and wavelet techniques, we identify quasiperiodic variations indicative of orbital motion in compact binary SMBH systems. The derived parameters point to highly compact configurations, with total system masses reaching up to ∼2.4 · 10 10 M ⊙ and near-equal mass ratios. The inferred orbital separations and periods suggest that these binaries are in a late inspiral stage, emitting gravitational waves in the nanohertz range. Estimated strain amplitudes indicate that such sources may be detectable by current and upcoming pulsar timing arrays, including IPTA, NANOGrav, and EPTA. These results support the hypothesis that a subset of bright blazars host tightly bound SMBH pairs and represent a promising population of low-frequency gravitational-wave sources.}, archive = {J_ApJ}, author = {Alexandr Volvach and Larisa Volvach and Mikhail Larionov}, doi = {10.3847/1538-4357/adfee2}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {60}, shortjournal = {The Astrophys. J.}, title = {Characterizing close binary supermassive black holes in blazars 3C 273, 3C 454.3, s0528+134, and AO 0235+164: Insights from multifrequency radio monitoring and gravitational-wave prospects}, volume = {992}, year = {2025}, }
• (2025). The effect of poloidal magnetic field and helicity injection in a breakout coronal mass ejection. ApJ, 992(1), 59. (www)

  @article{ , abstract = {Coronal mass ejections (CMEs), as crucial drivers of space weather, necessitate a comprehensive understanding of their initiation and evolution in the solar corona in order to better predict their propagation. Solar Cycle 24 exhibited lower sunspot numbers compared to Solar Cycle 23, along with a decrease in the heliospheric magnetic pressure. Consequently, a higher frequency of weak CMEs was observed during Solar Cycle 24. Forecasting CMEs is vital, and various methods, primarily involving the study of the global magnetic parameters using data sets like Space-weather Helioseismic and Magnetic Imager Active Region Patches, have been employed in earlier works. In this study, we perform numerical simulations of CMEs within a magnetohydrodynamics framework using Message Passing Interface–Adaptive Mesh Refinement Versatile Advection Code in 2.5D. By employing the breakout model for CME initiation, we introduce a multipolar magnetic field configuration within a background bipolar magnetic field, inducing shear to trigger the CME eruption. Our investigation focuses on understanding the impact of the background global magnetic field on CME eruptions. Furthermore, we analyze the evolution of various global magnetic parameters in distinct scenarios (failed eruption, single eruption, and multiple eruptions) resulting from varying amounts of helicity injection in the form of shear at the base of the magnetic arcade system. Our findings reveal that an increase in the strength of the background poloidal magnetic field constrains CME eruptions. Furthermore, we establish that the growth rate of absolute net current helicity is the crucial factor that determines the likelihood of CME eruptions.}, archive = {J_ApJ}, author = {Nitin Vashishtha and Vaibhav Pant and Dana-Camelia Talpeanu and Dipankar Banerjee and Shantanu Rastogi}, doi = {10.3847/1538-4357/adff54}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {59}, shortjournal = {The Astrophys. J.}, title = {The effect of poloidal magnetic field and helicity injection in a breakout coronal mass ejection}, volume = {992}, year = {2025}, }
• (2025). The impact of enhanced extreme-ultraviolet flux on the upper atmosphere of earth-like exoplanets. ApJ, 992(1), 58. (www)

  @article{ , abstract = {Identifying Earth-like planets outside our solar system is a leading research goal in astronomy, but determining if candidate planets have atmospheres, and more importantly if they can retain atmospheres, is still out of reach. In this paper, we present our study on the impact of enhanced extreme-ultraviolet (EUV) flux on the stability and escape of the upper atmosphere of an Earth-like exoplanet using the Global Ionosphere and Thermosphere Model. We also investigate the differences between 1D and 3D solutions. We use a baseline case of EUV flux experienced at the Earth, and multiply this flux by a constant factor going up to 50. Our results show a clear evidence of an inflated and elevated ionosphere due to enhanced EUV flux, and they provide a detailed picture of how different heating and cooling rates, as well as the conductivity, are changing at each EUV flux level. Our results also demonstrate that 1D solutions are limited in their ability to capture a global atmosphere that is not uniform. We find that a threshold EUV flux level for a stable atmosphere occurs around a factor of 10 times the baseline level, where EUV fluxes above this level indicate a rapidly escaping atmosphere. This threshold EUV flux translates to about 0.3 au for a planet orbiting the Sun. Thus, our findings indicate that an Earth-like exoplanet orbiting its host star in a close-in orbit is likely to lose its atmosphere quickly.}, archive = {J_ApJ}, author = {Lukas Hanson and Ofer Cohen and Aaron J. Ridley and Alex Glocer}, doi = {10.3847/1538-4357/adff7f}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {58}, shortjournal = {The Astrophys. J.}, title = {The impact of enhanced extreme-ultraviolet flux on the upper atmosphere of earth-like exoplanets}, volume = {992}, year = {2025}, }
• (2025). Metallicity of the double red clump in the milky way bulge. ApJ, 992(1), 57. (www)

  @article{ , abstract = {We present a reanalysis of the metallicity of the double red clump (RC) stars from the Milky Way bulge. Two leading explanations for the existence of the double RC concern possible differences in chemical composition (multiple populations of stars) or distance (X-shaped bulge). We aim to verify the chemical composition hypothesis by determining the mean metallicity of each RC. We use infrared photometric data and metallicities from a previous study (that are based on the Michigan/Magellan Fiber System spectra). In contrast with previous studies, we assign stars to RCs or the red giant branch using a Bayesian approach. Our resulting difference between mean metallicity of the two RCs equals: 0.2{3}_{-0.24}^{+0.19} or 0.2{8}_{-0.18}^{+0.17}\,{\rm{dex}} , if the red giant branch bump is included or not, respectively. Because of the high statistical error, the result does not confirm the multiple populations hypothesis.}, archive = {J_ApJ}, author = {Zofia Budzik and Matylda Łukaszewicz and Radosław Poleski}, doi = {10.3847/1538-4357/ae0329}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {57}, shortjournal = {The Astrophys. J.}, title = {Metallicity of the double red clump in the milky way bulge}, volume = {992}, year = {2025}, }
• (2025). Study of neutron capture nucleosynthesis based on Post–Asymptotic giant branch stars. ApJ, 992(1), 56. (www)

  @article{ , abstract = {The intermediate neutron-capture process ( i -process) may occur during proton ingestion events, with post–asymptotic giant branch (AGB) stars considered among its potential astrophysical sites. This study selected the post-AGB star IRAS 14325-6428, which is enriched in both Ba ([Ba/Fe] = 2.08) and Eu ([Eu/Fe] = 1.25), to investigate its elemental abundance pattern and the odd-isotope ratio of Ba. The atmospheric parameters of the star, T eff = 7900 ± 80 K, log g = 1.2 ± 0.10, [Fe/H]= −0.75 ± 0.05, and ξ t = 5.8 ± 0.20 km s −1 , were derived, taking into account non–local thermodynamic equilibrium effects. We match the observed elemental abundances with the pattern of abundance distributions of various astrophysical processes and find that the s - and r -processes alone or together cannot explain the heavy element enrichment mechanism in this star. The observed odd-isotope ratio of barium is f odd,Ba = 0.25 ± 0.08, suggesting that the heavy elements in post-AGB star IRAS 14325-6428 may be contaminated by the i -process.}, archive = {J_ApJ}, author = {Miao Tian and Wenyuan Cui and Jian-Rong Shi and Jin-Xiao Qin and Hongjie Li and Fang Wen and Zhenyan Huo}, doi = {10.3847/1538-4357/ae03b5}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {56}, shortjournal = {The Astrophys. J.}, title = {Study of neutron capture nucleosynthesis based on Post–Asymptotic giant branch stars}, volume = {992}, year = {2025}, }
• (2025). Extended and compact ortho-H2D+ structures close to the moment of star formation: Evidence from ALMA-ACA observations in taurus. ApJ, 992(1), 55. (www)

  @article{ , abstract = {Observing and characterizing pre- and protostellar cores in the earliest and densest stages of star formation is challenging due to their short timescales and high densities, limiting the suitable tracers and targets. We conducted Atacama Large Millimeter/submillimeter Array-Atacama Compact Array standalone observations of ortho-H 2 D + (1 1,0 –1 1,1 ) emission, which is believed to trace cold high-density regions, toward three dense cores in the Taurus molecular cloud: (1) L1544, likely in the densest prestellar phase; (2) MC 35 mm, a candidate for the first hydrostatic core; and (3) MC 27/L1521F, which hosts a Class 0 very-low-luminosity object. These observations provide high angular resolution data for the line across a set of cores selected to represent consecutive stages around the onset of star formation, offering a unique opportunity to trace the time evolution of ∼10 4 yr. With the single-dish total-power array, we detected ortho-H 2 D + emission in all three cores, revealing its presence over scales of ∼10,000 au. In the interferometric 7 m array data with a beam size of 3 \mathop{.}\limits^{^{\prime\prime} } 5 (∼500 au), emission was detected only toward the central continuum source of MC 35 mm, with a significance of ∼3 σ . No significant detections were found in the other targets, placing an upper limit on the H 2 D + abundance of ∼10 −11 in the dense components traced by the interferometric continuum emission. These results suggest that ortho-H 2 D + predominantly exhibits an extended distribution over several thousand au in the early stages of star formation. Detection in compact, dense central structures may only be achieved within a few ×10 4 yr immediately before or after protostar formation.}, archive = {J_ApJ}, author = {Kazuki Tokuda and Kenji Furuya and Naofumi Fukaya and Kengo Tachihara and Ken’ichi Tatematsu and Shingo Nozaki and Nami Sakai and Yuri Aikawa and Kazuya Saigo and Toshikazu Onishi and Masahiro N. Machida}, doi = {10.3847/1538-4357/ae0460}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {55}, shortjournal = {The Astrophys. J.}, title = {Extended and compact ortho-H2D+ structures close to the moment of star formation: Evidence from ALMA-ACA observations in taurus}, volume = {992}, year = {2025}, }
• (2025). HST proper motions of andromeda v and andromeda VI. ApJ, 992(1), 54. (www)

  @article{ , abstract = {We measure the absolute proper motions of Andromeda V (And V) and Andromeda VI/Pegasus (And VI) dwarf galaxies, satellites of M31 located near its galactic plane. And VI is located the farthest from M31 among the six satellites with currently measured proper motions. A combination of Advanced Camera for Surveys/wide filed channel (WFC) and WFPC2 exposures is utilized, spanning a 20 yr time baseline. The WFPC2 exposures are processed using a recently developed deep-learning centering procedure as well as the most up-to-date astrometric calibration of the camera. We use on the order of 100 background galaxies per satellite to determine the correction to absolute proper motion. For And V, we obtain an absolute proper motion of {({\mu }_{\alpha },{\mu }_{\delta })}_{\mathrm{And}\,{\rm{V}}}=(26.1\pm 21.5,-74.2\pm 19.1)\,\mu \mathrm{as} yr −1 . For And VI, we obtain an absolute proper motion of {({\mu }_{\alpha },{\mu }_{\delta })}_{\mathrm{And}\,\mathrm{VI}}=(-1.6\pm 12.3,-52.6\pm 11.2)\,\mu \mathrm{as} yr −1 . Orbit integrations and analyses are made for these two Andromeda satellites using two estimates of both the mass and proper motion of M31. It is found that And V has an orbit consistent within errors with alignment with M31’s disk and counter orbiting it, although this alignment is not well constrained. And VI’s orbit is better determined and is very much consistent with coorbiting with M31’s disk. While currently at a distance of ∼280 kpc from M31, And VI will remain beyond a distance of ∼90 kpc from M31, thus experiencing low tidal influence compared to the other M31 satellites with known orbits. Both satellites are determined to be well-bound to M31.}, archive = {J_ApJ}, author = {Dana I. Casetti-Dinescu and Marcel S. Pawlowski and Terrence M. Girard and Kosuke Jamie Kanehisa and Max Martone and Alexander Petroski}, doi = {10.3847/1538-4357/ae0479}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {54}, shortjournal = {The Astrophys. J.}, title = {HST proper motions of andromeda v and andromeda VI}, volume = {992}, year = {2025}, }
• (2025). Selecting clusters and protoclusters via stellar mass density. II. application to HSC-SSP observations. ApJ, 992(1), 53. (www)

  @article{ , abstract = {We present a selection of candidates of clusters and protoclusters of galaxies identified in the photometric data of the HSC-SSP Wide Public Data Release 3 (PDR3), spanning the redshift range 0.1 ≤ z ≤ 2. The selection method, detailed in Vicentin et al., involves detecting massive galaxies located in high-density regions of matter, identified as potential central dominant galaxies, i.e., (proto)brightest cluster galaxies (protoBCGs or BCGs). Probabilistic criteria based on proximity to the candidate central galaxy and the expected stellar mass of member galaxies are applied to identify likely members of each structure. We produced updated photometric redshift estimates using deep learning methods trained on a data set combining spectroscopic redshifts from the HSC-SSP Wide PDR3, high-accuracy photometric redshifts from the COSMOS2020 catalog, and midinfrared data from the unWISE catalog for matched sources. Our method achieves a predicted purity of ∼90% in detecting (proto)clusters, with ≳65% correctly identifying the (proto)BCG. A total of 16,007 candidate (proto)clusters were identified over an effective area of ∼850 deg 2 within the HSC-SSP Wide footprint. Comparisons with other existing catalogs reveal a good level of consistency, while also highlighting that different methods yield complementary discoveries. We further compare richness and halo masses from our optical catalog with those from recent X-ray cluster catalogs (eROSITA and MCXC-II), finding a moderate positive correlation and a scatter of ∼0.4 dex. This catalog provides a valuable new set of targets for the Prime Focus Spectrograph instrument.}, archive = {J_ApJ}, author = {Marcelo C. Vicentin and Laerte Sodré and Michael A. Strauss and Erik V. R. de Lima and Pablo Araya-Araya}, doi = {10.3847/1538-4357/adff72}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {53}, shortjournal = {The Astrophys. J.}, title = {Selecting clusters and protoclusters via stellar mass density. II. application to HSC-SSP observations}, volume = {992}, year = {2025}, }
• (2025). Selecting clusters and protoclusters via stellar mass density. i. method and tests on mock HSC-SSP catalogs. ApJ, 992(1), 52. (www)

  @article{ , abstract = {We present an algorithm designed to identify galaxy (proto)clusters in wide-area photometric surveys by first selecting their dominant galaxy—i.e., the brightest cluster galaxy (BCG) or protoBCG—through the local stellar mass density traced by massive galaxies. We focus on its application to the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) Wide Survey to detect candidates up to z ∼ 2. In this work, we apply the method to mock galaxy catalogs that replicate the observational constraints of the HSC-SSP Wide Survey. We derive functions that describe the probability of a massive galaxy being the dominant galaxy in a structure as a function of its stellar mass density contrast within a given redshift interval. We show that galaxies with probabilities greater than 50% yield a sample of BCGs/protoBCGs with ≳65% purity, where most of the contamination arises from galaxies in massive groups below our cluster threshold. Using the same threshold, the resulting (proto)cluster sample achieves 80% purity and 50% completeness for halos with M halo ≥ 10 14 M ⊙ , reaching nearly 100% completeness for M halo ≥ 10 14.5 M ⊙ . We also assign probabilistic membership to surrounding galaxies based on stellar mass and distance to the dominant galaxy, from which we define the cluster richness as the number of galaxies more likely to be true members than contaminants. This allows us to derive a halo mass–richness relation. In a companion paper, we apply the algorithm to the HSC-SSP data and compare our catalog with others based on different cluster-finding techniques and X-ray detections.}, archive = {J_ApJ}, author = {Marcelo C. Vicentin and Pablo Araya-Araya and Laerte Sodré Jr. and Michael A. Strauss}, doi = {10.3847/1538-4357/adff86}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {52}, shortjournal = {The Astrophys. J.}, title = {Selecting clusters and protoclusters via stellar mass density. i. method and tests on mock HSC-SSP catalogs}, volume = {992}, year = {2025}, }
• (2025). High-resolution simulation of coronal mass Ejection–Corotating interaction region interactions: Mesoscale solar wind structure formation observable by the SWIFT constellation. ApJ, 992(1), 51. (www)

  @article{ , abstract = {We present an unprecedented simulation of how two large-scale heliospheric transients—a coronal mass ejection (CME) and a corotating stream interaction region—collide, producing a dramatic increase in the complexity of the CME due to formation of mesoscale flux ropes. These structures are captured for the first time by a numerical simulation using high-resolution numerical grids. The circumstances that lead to the formation of these complex structures occur during solar maximum. At the time of the solar maximum taken for this study, 2014 September, the heliospheric current sheet is vertically inclined running over the poles, allowing the CME to impact a preceding slow-fast stream interaction region. The simulation is performed with the Alfvén Wave Solar Atmosphere Model (or AWSoM), with which we initiate a fast CME from active region (AR) 12158 by applying a Gibson–Low magnetic flux rope. Magnetic reconnection within the leading extremity of the CME results in the formation of mesoscale flux ropes, which contain sufficiently strong magnetic fields (∼30 nT) to affect planetary magnetospheres. Finally, we use a tetrahedral configuration of four virtual probes, corresponding to the Space Weather Investigation Frontier mission concept, to show that the mission can uniquely resolve the spatial characteristics and temporal evolution of reconnecting current sheets within the CME, as well as the resulting mesoscale structures.}, archive = {J_ApJ}, author = {W. B. Manchester and Nishtha Sachdeva and Emilia Kilpua and Matti Ala-Lahti and Shirsh Lata Soni and Zhenguang Huang and Hongfan Chen and Aniket Jivani and Bart van der Holst and Adam Szabo and Mojtaba Akhavan-Tafti}, doi = {10.3847/1538-4357/adf855}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {51}, shortjournal = {The Astrophys. J.}, title = {High-resolution simulation of coronal mass Ejection–Corotating interaction region interactions: Mesoscale solar wind structure formation observable by the SWIFT constellation}, volume = {992}, year = {2025}, }
• (2025). On the meaning of the dynamo radius in giant planets with stable layer. ApJ, 992(1), 50. (www)

  @article{ , abstract = {Current structure models of Jupiter and Saturn suggest that helium becomes immiscible in hydrogen in the outer part of the planets’ electrically conducting regions. This likely leads to a layer in which overturning convection is inhibited due to a stabilizing compositional gradient. The presence of such a stably stratified layer impacts the location and mechanism of convectively driven dynamo action. Juno’s measurements of Jupiter’s magnetic field enabled an estimate of its dynamo radius based on the magnetic Lowes spectrum. A depth of ∼0.8 R J is obtained, where 1 R J is Jupiter’s radius. This is rather deep, considering that the electrical conductivity inside Jupiter is expected to reach significant values at ∼0.9 R J . Here, we use three-dimensional numerical dynamo simulations to explore the effects of the existence and location of a stably stratified helium rain layer on both the inferred Lowes radius and the location of the radial extent of dynamo action. We focus on a Jupiter-like internal structure and electrical conductivity profile. We find that for shallower stable layers, there is no magnetic field generation occurring above the stable layer, and the effective dynamo radius and the inferred Lowes radius are at the base of the layer. For deeper stable layers, Lowes radii of ∼0.87 R J are inferred as a shallow secondary dynamo operates above the stable layer. Our results strongly suggest the existence of a stable layer extending from ∼0.8 R J up to at least ∼0.9 R J inside Jupiter. The physical origin of this extended stable layer and its connection to helium rain remain to be elucidated.}, archive = {J_ApJ}, author = {Paula N. Wulff and Hao Cao and Jonathan M. Aurnou}, doi = {10.3847/1538-4357/adf736}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {50}, shortjournal = {The Astrophys. J.}, title = {On the meaning of the dynamo radius in giant planets with stable layer}, volume = {992}, year = {2025}, }
• (2025). A tale of two stars: X-ray and ground-based observations of two diverging stars in Taurus–Auriga. ApJ, 992(1), 49. (www)

  @article{ , abstract = {We present XMM-Newton observations and near-simultaneous optical observations of the classical T Tauri star SU Auriga and the nearby Herbig Ae star AB Auriga, two members of the 4 Myr old Taurus–Auriga star-forming region. Combining these observations with archival ones, we examine data covering more than two decades, aiming to determine the X-ray stability of these two stars over that period. We model the X-ray spectra for each star using XSPEC models and present the results of this modeling. For SU Aur, we find evidence for absorption by both the stellar corona and an accretion column, supported by both the best-fit model to the X-ray spectra and the variable, self-absorbed H α profile observed in the optical. We observe a single flare at the end of the observing period for SU Aur.}, archive = {J_ApJ}, author = {Mackenna L. Wood and Hans Moritz Günther and P. C. Schneider and Scott J. Wolk}, doi = {10.3847/1538-4357/adf96a}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {49}, shortjournal = {The Astrophys. J.}, title = {A tale of two stars: X-ray and ground-based observations of two diverging stars in Taurus–Auriga}, volume = {992}, year = {2025}, }
• (2025). The interstellar medium in i zw 18 seen with JWST/MIRI. i. highly ionized gas. ApJ, 992(1), 48. (www)

  @article{ , abstract = {We present JWST/MIRI spectra from the Medium-Resolution Spectrometer of I Zw 18, a nearby dwarf galaxy with a metallicity of ∼3% solar. Its proximity enables a detailed study of highly ionized gas that can be interpreted in the context of newly discovered high-redshift dwarf galaxies. We derive aperture spectra centered on 11 regions of interest; the spectra show very low extinction, A V ≲ 0.1, consistent with optical determinations. The gas is highly ionized; we have detected 10 fine-structure lines, including [O iv ] 25.9 μ m with an ionization potential (IP) of ∼55 eV, and [Ne v ] 14.3 μ m with an IP of ∼97 eV. The ionization state of I Zw 18 falls at the extreme upper end of all of the line ratios we analyzed, but not coincident with galaxies containing an accreting massive black hole (active galactic nucleus). Comparison of the line ratios with state-of-the-art photoionization and shock models suggests that the high-ionization state in I Zw 18 is not due to shocks. Rather, it can be attributed to metal-poor stellar populations with a self-consistent contribution of X-ray binaries or ultra-luminous X-ray sources. It could also be partially due to a small number of hot low-metallicity Wolf−Rayet stars ionizing the gas; a small fraction (a few percent) of the ionization could come from an intermediate-mass black hole. Our spectroscopy also revealed four 14 μ m continuum sources, ≳30–100 pc in diameter, three of which were not previously identified. Their properties are consistent with H ii regions ionized by young star clusters.}, archive = {J_ApJ}, author = {L. K. Hunt and A. Aloisi and M. G. Navarro and R. J. Rickards Vaught and B. T. Draine and A. Adamo and F. Annibali and D. Calzetti and S. Hernandez and B. L. James and M. Mingozzi and R. Schneider and M. Tosi and B. Brandl and M. G. del Valle-Espinosa and F. Donnan and A. S. Hirschauer and M. Meixner and D. Rigopoulou and C. T. Richardson and J. M. Levanti and A. R. Basu-Zych}, doi = {10.3847/1538-4357/adfb69}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {48}, shortjournal = {The Astrophys. J.}, title = {The interstellar medium in i zw 18 seen with JWST/MIRI. i. highly ionized gas}, volume = {992}, year = {2025}, }
• (2025). 47 tuc in rubin data preview 1. exploring early LSST data and science potential. ApJ, 992(1), 47. (www)

  @article{ , abstract = {We present analyses of the early data from Rubin Observatory’s Data Preview 1 (DP1) for the field of the globular cluster 47 Tuc. The DP1 data set for 47 Tuc includes four nights of observations from the Rubin Commissioning Camera (LSSTComCam), covering multiple bands ( ugriy ). We address challenges of crowding in the inner region of the cluster and toward the SMC in DP1, and demonstrate improved star–galaxy separation by fitting fifth-degree polynomials to the stellar loci in color–color diagrams and applying multidimensional sigma clipping. We compile a catalog of 3576 probable 47 Tuc member stars selected via a combination of isochrone, Gaia proper-motion, and color–color space matched filtering. We explore the sources of photometric scatter in the 47 Tuc color–color sequence, evaluating contributions from various potential sources, including differential extinction within the cluster. Finally, of the 72 well-characterized variables in the field, we recover three known variable stars, including two RR Lyrae and one eclipsing binary, in the coadd-based object catalog, and identify 62 in the difference image-based object catalog. Although the DP1 lightcurves have sparse temporal sampling, they appear to follow the patterns of densely sampled literature lightcurves well. Despite some data limitations for crowded-field stellar analysis, DP1 demonstrates the promising scientific potential for future LSST data releases.}, archive = {J_ApJ}, author = {Yumi Choi and Knut A. G. Olsen and Jeffrey L. Carlin and Yuankun (David) Wang and Fred Moolekamp and Abhijit Saha and Ian Sullivan and Colin T. Slater and Douglas L. Tucker and Christina L. Adair and Peter S. Ferguson and Yijung Kang and Karla Peña Ramírez and Markus Rabus}, doi = {10.3847/1538-4357/adfb70}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {47}, shortjournal = {The Astrophys. J.}, title = {47 tuc in rubin data preview 1. exploring early LSST data and science potential}, volume = {992}, year = {2025}, }
• (2025). Pitch-angle focusing and scattering of TeV galactic cosmic rays propagating in local interstellar magnetic fields. ApJ, 992(1), 46. (www)

  @article{ , abstract = {We use Tibet AS γ anisotropy data for 4 TeV cosmic rays to investigate the properties of the pitch-angle focusing and diffusion caused by the interstellar magnetic field and turbulence. The pitch-angle distribution (PAD) in the local interstellar medium is reconstructed from the anisotropy map using Liouville mapping. Under the diffusion approximation, we found that the expected pitch-angle diffusion coefficient is an asymmetric function of pitch angle. Without organized magnetic/cross-helicities of interstellar magnetic field turbulence, such an asymmetry can be interpreted as evidence of focusing by a nonuniform magnetic field. A model incorporating a symmetric pitch-angle diffusion coefficient and focusing effects reproduces the observed PAD. It also indicates that the length of the magnetic field inhomogeneity is a few times the parallel mean free path of TeV particles, and that the interstellar field weakens along the field direction into the northern Galactic halo. The inferred pitch-angle diffusion coefficient might suggest scattering by compressible magnetic field turbulence. Additionally, we estimate that the parallel and perpendicular flux gradients have lengths ∼1.72 κ 29 kpc and ∼7.76 pc, respectively, where κ 29 is the spatial diffusion coefficient in units of 10 29 cm 2 s −1 . The lack of a significant observed diffusion flow perpendicular to the local magnetic field puts an upper bound on the perpendicular-to-parallel local diffusion coefficient ratio of 0.00045/ κ 29 . Moreover, we show that the temporal rate of change is no more than 7.08 × 10 −7 / κ 29 yr −1 in relative intensity.}, archive = {J_ApJ}, author = {N. D. Maalal and M. Zhang}, doi = {10.3847/1538-4357/adfc52}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {46}, shortjournal = {The Astrophys. J.}, title = {Pitch-angle focusing and scattering of TeV galactic cosmic rays propagating in local interstellar magnetic fields}, volume = {992}, year = {2025}, }
• (2025). COSMOS-web: MIRI data reduction and number counts at 7.7 μm using JWST. ApJ, 992(1), 45. (www)

  @article{ , abstract = {The COSMOS-Web survey is the largest JWST Cycle 1 General Observer program, covering a contiguous ∼0.54 deg 2 area with NIRCam imaging in four broadband filters and a noncontiguous ∼0.2 deg 2 with parallel MIRI imaging in a single broadband filter, F770W. Here we present a comprehensive overview of the MIRI imaging observations, the data reduction procedure, the COSMOS-Web MIRI photometric catalog, and the first data release including the entire COSMOS-Web MIRI coverage. Data reduction primarily relies on the JWST Science Calibration Pipeline, supplemented by custom background subtraction to mitigate prominent instrumental artifacts and sky background within the MIRI images. We reach 5 σ (point source) limiting depths ( m F770W ∼ 25.51 based on r ∼ 0 \mathop{.}\limits^{\unicode{x02033}} 3 circular apertures) that are significantly better than initial expectations. Using the images provided in this release, we construct a photometric catalog and compare the F770W flux densities to the Spitzer/IRAC CH4 measurements from the COSMOS2020 catalog (for CH4 detections with signal-to-noise ratio S/N > 5). We find that these are in reasonable agreement with a small median offset of <0.05 mag. We also derive robust 7.7 μ m number counts spanning five orders of magnitude in flux (∼0.2–2300 μ Jy)—making COSMOS-Web the only JWST survey to date to sample such a large flux range—which are in good agreement with estimates from other JWST and IRAC surveys.}, archive = {J_ApJ}, author = {Santosh Harish and Jeyhan S. Kartaltepe and Daizhong Liu and Anton M. Koekemoer and Caitlin M. Casey and Maximilien Franco and Hollis B. Akins and Olivier Ilbert and Marko Shuntov and Nicole E. Drakos and Mike Engesser and Andreas L. Faisst and Ghassem Gozaliasl and Crystal L. Martin and Michaela Hirschmann and Vasily Kokorev and Erini Lambrides and Henry Joy McCracken and Jed McKinney and Louise Paquereau and Jason Rhodes and Brant E. Robertson}, doi = {10.3847/1538-4357/adfa1e}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {45}, shortjournal = {The Astrophys. J.}, title = {COSMOS-web: MIRI data reduction and number counts at 7.7 μm using JWST}, volume = {992}, year = {2025}, }
• (2025). Revisiting the gas dynamics of henize 2–10: Possible drivers of the starburst. ApJ, 992(1), 44. (www)

  @article{ , abstract = {The triggers of starburst episodes are a key component to our understanding of the baryon cycle in galaxies. Galaxy mergers are a commonly suggested catalyst for starbursts, but once the galaxies coalesce into a single kinematically disturbed system, their merger history can be difficult to assess. This is particularly true for dwarf galaxies, which are expected to dominate the merger rate at all redshifts due to their large numbers. One such dwarf galaxy undergoing an enigmatic starburst episode is Henize 2–10, which appears to be isolated. Possible scenarios that might have caused the starburst episode include a previous merger or stochastic processes within the galaxy itself, such as self-regulation via feedback processes. We present new Very Large Array 21 cm observations and unpublished archival Combined Array for Research in Millimeter-wave Astronomy CO data to investigate the dynamical state and star formation activity in the galaxy. We do not detect an H i tail consistent with the structure reported by H. A. Kobulnicky et al. ( 1995 ), which was suggested as evidence for a merger or interaction, but rather, these new observations indicate an extended H i distribution. We also find that the H i appears dynamically decoupled from an extended CO feature (inferred to be a tidal tail in previous work), suggesting large-scale dynamical processes of some type are affecting the gas in this system. We provide a metaanalysis of available results to enhance our understanding of what might be triggering the starburst episode in Henize 2–10, and speculate that the large CO feature could be falling into the galaxy and potentially trigger starburst activity.}, archive = {J_ApJ}, author = {Josephine M. Dalsin and Allison H. Costa and Remy Indebetouw and Kelsey E. Johnson and Natalie O. Butterfield and Sabrina Stierwalt}, doi = {10.3847/1538-4357/adf857}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {44}, shortjournal = {The Astrophys. J.}, title = {Revisiting the gas dynamics of henize 2–10: Possible drivers of the starburst}, volume = {992}, year = {2025}, }
• (2025). Blowout expansion of overlying coronal loops and subsequent filament eruption: AIA and RHESSI observations. ApJ, 992(1), 43. (www)

  @article{ , abstract = {We present a comprehensive multiwavelength analysis of a coronal mass ejection (CME) on 2014 January 8 from the active region (AR) NOAA 11947 by analyzing the data from Atmospheric Imaging Assembly (AIA) on board Solar Dynamics Observatory, RHESSI, and Hiraiso Radio Spectrograph. The CME is associated with an M3.6 flare and filament eruption. Observations from the AIA 171 Å images reveal the origin of pre-CME arcade ≈1 hr prior to the eruptive event. Before the onset of event, the hot AIA 131 and 94 Å images exhibit an existence of a hot flux rope, which on eruption results in the activation and eruptive expansion of the pre-CME coronal arcade. The eruptive process of pre-CME arcade consists of a slow rise evolution with a speed ≈3 km s −1 , “arcade-to-bubble” transformation, and blowout expansion of the CME-bubble with a fast speed of ≈400 km s −1 . A differential emission measure analysis suggests the presence of multithermal plasma in the bubble-structure and strong plasma heating at the core of the AR. A blowout expansion of CME is accompanied with multiple type III and a split-band type II radio bursts in association with X-ray emission up to 50 keV energies from its source region. Our observations reveal that the formation and expansion of the CME-bubble serve as the earliest signatures of the CME, capturing its development in the low corona. Concurrent X-ray and radio emissions further highlight the critical role of large-scale magnetic reconnection in powering both the flare emissions and the early evolution and dynamics of the CME.}, archive = {J_ApJ}, author = {Hema Kharayat and Bhuwan Joshi and Binal D. Patel and Ramesh Chandra}, doi = {10.3847/1538-4357/adf95f}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {43}, shortjournal = {The Astrophys. J.}, title = {Blowout expansion of overlying coronal loops and subsequent filament eruption: AIA and RHESSI observations}, volume = {992}, year = {2025}, }
• (2025). Spatially resolved [O iii] emission line kinematics of reverberation-mapped active galactic nuclei with the keck cosmic web imager. ApJ, 992(1), 42. (www)

  @article{ , abstract = {We present optical integral-field spectroscopic data of ten nearby (0.02 ≤ z ≤ 0.05) Seyfert 1 galaxies taken with the Keck Cosmic Web Imager. We map the spatially resolved kinematics of the [O iii ] gas and stars, and investigate the alignments between their global kinematic position angles (PAs). Large-scale gas motions are primarily dominated by rotation and are kinematically aligned with the stars (ΔPA ≤ 30°). However, eight galaxies exhibit nonrotational kinematic signatures (e.g., kinematic twists, possible outflows) in their ionized gas velocity fields near the nucleus. We compare aperture-wide measurements of the gas and stellar velocity dispersions ( σ gas and σ ⋆ ) to test the use of the width of the [O iii ] line core as a surrogate for σ ⋆ . Direct comparisons between σ gas and σ ⋆ show that σ gas tends to underestimate σ ⋆ , and thus is not a reliable tracer of σ ⋆ for our selected galaxies. We measure the extent of the narrow-line region (NLR) using several definitions, resulting in sizes of ∼0.1–10 kpc. For a given [O iii ] luminosity, our NLR sizes derived from the [O iii ]/H β flux ratio or an [O iii ] isophotal radius are an order of magnitude larger than those measured from past imaging data.}, archive = {J_ApJ}, author = {Raymond P. Remigio and Vivian U and Aaron J. Barth and Nico Winkel and Vardha N. Bennert and Tommaso Treu and Matthew A. Malkan and Sebastian Contreras and Peter R. Williams and Jordan N. Runco and Liam Hunt}, doi = {10.3847/1538-4357/adfe5d}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {42}, shortjournal = {The Astrophys. J.}, title = {Spatially resolved [O iii] emission line kinematics of reverberation-mapped active galactic nuclei with the keck cosmic web imager}, volume = {992}, year = {2025}, }
• (2025). Lopsided and bulging distribution of satellites around paired halos. II. 3D analysis and dependence on projection and selection effects. ApJ, 992(1), 41. (www)

  @article{ , abstract = {We use the Illustris-TNG300 simulation to investigate the anisotropic distribution of subhalos in/around dark matter halo pairs. We measure the position angle ( θ ) of each subhalo by the angle between the line connecting it to the nearest host halo and the line connecting the paired halos, and examine P(\cos \theta ) (the distribution of \cos \theta of all subhalos) for halo pairs with various separations ( d sep ), primary halo masses ( M p ), and secondary-to-primary halo mass ratios ( M s / M p ). We find that P(\cos \theta ) generally exhibits a combined result of two distinct features: the “bulging” distribution characterized by an overabundance along the pairwise direction, and the “lopsided” distribution showing an overabundance in the region between the paired halos. The bulging signal is stronger for halo pairs with larger d sep and smaller M p , while the lopsidedness strengthens as M p increases. Both signals depend weakly on M s / M p , and are primarily contributed by subhalos that are relatively distant from the host halos. Remarkably, these measurements can be broadly reproduced by the overlap effect, provided the spatial alignment of the halos is properly taken into account. Our findings suggest distinct origins: lopsidedness arises from simple halo overlap, while bulging reflects alignment with large-scale filaments. We examine the impact of projection and selection effects by conducting the same analysis in two dimensions and in a mock catalog that replicates the selection effects of the Sloan Digital Sky Survey galaxy sample. We find that the 3D-to-2D projection significantly suppresses the bulging distribution, with particularly strong effects at large d sep , small M p , and large M s / M p .}, archive = {J_ApJ}, author = {Qinglin Ma and Cheng Li and Yanhan Guo}, doi = {10.3847/1538-4357/adfede}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {41}, shortjournal = {The Astrophys. J.}, title = {Lopsided and bulging distribution of satellites around paired halos. II. 3D analysis and dependence on projection and selection effects}, volume = {992}, year = {2025}, }
• (2025). Dolphin: A fully automated forward-modeling pipeline powered by artificial intelligence for galaxy-scale strong lenses. ApJ, 992(1), 40. (www)

  @article{ , abstract = {Strong gravitational lensing is a powerful tool for probing the internal structure and evolution of galaxies, the nature of dark matter, and the expansion history of the Universe, among many other scientific applications. For almost all of these science cases, modeling the lensing mass distribution is essential. For that, forward modeling of imaging data to the pixel level is the standard method used for galaxy-scale lenses. However, the traditional workflow of forward lens modeling necessitates a significant amount of human investigator time, requiring iterative tweaking and tuning of the model settings through trial and error. An automated lens-modeling pipeline can substantially reduce the need for human investigator time. In this paper, we present dolphin , an automated lens-modeling pipeline that combines artificial intelligence with the traditional forward-modeling framework to enable full automation of the modeling workflow. dolphin uses a neural network model to perform visual recognition of the strong lens components, then autonomously sets up a lens model with appropriate complexity and fits the model with the modeling engine, lenstronomy . Thanks to the versatility of lenstronomy , dolphin can autonomously model both galaxy–galaxy and galaxy–quasar strong lenses.}, archive = {J_ApJ}, author = {Anowar J. Shajib and Nafis Sadik Nihal and Chin Yi Tan and Vedant Sahu and Simon Birrer and Tommaso Treu and Joshua Frieman}, doi = {10.3847/1538-4357/adf95c}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {40}, shortjournal = {The Astrophys. J.}, title = {Dolphin: A fully automated forward-modeling pipeline powered by artificial intelligence for galaxy-scale strong lenses}, volume = {992}, year = {2025}, }
• (2025). A deep, high-angular-resolution 3D dust map of the southern galactic plane. ApJ, 992(1), 39. (www)

  @article{ , abstract = {We present a deep, high-angular-resolution 3D dust map of the southern Galactic plane over 239° < l < 6° and ∣ b ∣ < 10° built on photometry from the DECaPS2 survey, in combination with photometry from VISTA Variables in the Via Lactea, the Two Micron All Sky Survey, and “Unofficial” Wide-field Infrared Survey Explorer and parallaxes from Gaia Data Release 3 where available. To construct the map, we first infer the distance, extinction, and stellar types of over 700 million stars using the brutus stellar inference framework with a set of theoretical MESA Isochrone and Stellar Tracks ( MIST ) stellar models. Our resultant 3D dust map has an angular resolution of 1^{\prime} \rm{}\,\rm{}\, roughly an order of magnitude finer than existing 3D dust maps and comparable to the angular resolution of the Herschel 2D dust emission maps. We detect complexes at the range of distances associated with the Sagittarius-Carina and Scutum-Centaurus arms in the fourth quadrant, as well as more distant structures out to a maximum reliable distance of d ≈ 10 kpc from the Sun. The map is sensitive up to a maximum extinction of roughly A V ≈ 12 mag. We publicly release both the stellar catalog and the 3D dust map, the latter of which can easily be queried via the Python package dustmaps . When combined with the existing Bayestar19 3D dust map of the northern sky, the DECaPS 3D dust map fills in the missing piece of the Galactic plane, enabling extinction corrections over the entire disk ∣ b ∣ < 10°. Our map serves as a pathfinder for the future of 3D dust mapping in the era of LSST and Roman, targeting regimes accessible with deep optical and near-infrared photometry but often inaccessible with Gaia.}, archive = {J_ApJ}, author = {Catherine Zucker and Andrew K. Saydjari and Joshua S. Speagle and Edward F. Schlafly and Gregory M. Green and Robert Benjamin and Joshua Peek and Gordian Edenhofer and Alyssa Goodman and Michael A. Kuhn and Douglas P. Finkbeiner}, doi = {10.3847/1538-4357/adfbe6}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {39}, shortjournal = {The Astrophys. J.}, title = {A deep, high-angular-resolution 3D dust map of the southern galactic plane}, volume = {992}, year = {2025}, }
• (2025). Recoiling black hole candidates from spatially offset broad emission lines in MaNGA. ApJ, 992(1), 38. (www)

  @article{ , abstract = {From the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey, we identify 14 off-nuclear broad (FWHM > 1000 km s −1 ) H α and/or H β emission line sources that indicate spatially offset active galactic nuclei (AGN) candidates. In addition to massive black holes (MBHs) in ongoing galaxy mergers, this selection can also find MBHs that have been ejected from the host galaxy nucleus due to MBH binary coalescence and asymmetric gravitational wave emission or the dynamical “slingshot” mechanism. Recoiling/slingshot MBHs are predicted to affect coevolution between MBHs and their host galaxies, and they are observational tracers of past binary MBH mergers and gravitational wave emission. This is the first systematic search through an integral field spectroscopy survey for ejected MBHs to enable uniform constraints on their surface densities. We find that 42% (6/14) have optical image counterparts consistent with galaxy stellar cores from infalling MBHs before the close binary MBH stage. The remaining 58% (8/14) have large broad line luminosities relative to their stellar core mass upper limits (∼2 times larger than for central AGN), suggesting merger-driven MBH accretion enhancements or potentially ejected MBHs. The signatures of AGN-ionized narrow emission lines for recoil/slingshot candidates are weaker by 68%, which is consistent with the ejected MBH scenario. The broad line projected velocity offsets range from ∼10 to 600 km s −1 and suggest motion within the host galaxy potentials. Finally, the implied recoiling MBH surface density upper limit is consistent with predictions that assume random spin orientations in MBH binaries.}, archive = {J_ApJ}, author = {R. Scott Barrows and Julia M. Comerford and James Negus and Francisco Muller-Sanchez}, doi = {10.3847/1538-4357/adfbf3}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {38}, shortjournal = {The Astrophys. J.}, title = {Recoiling black hole candidates from spatially offset broad emission lines in MaNGA}, volume = {992}, year = {2025}, }
• (2025). Observational analysis of multithermal counterstreaming flows in a forming filament and their relationship with local heating at filament footpoints. ApJ, 992(1), 37. (www)

  @article{ , abstract = {Utilizing high-resolution imaging and spectroscopic observations from the New Vacuum Solar Telescope, the Interface Region Imaging Spectrograph, and the Solar Dynamics Observatory, we investigated the nature and origin of counterstreaming flows within a forming active region filament. The ever-present counterstreaming flows observed within the filament are identified as interleaved unidirectional mass flows in opposing directions occurring in neighboring threads. Multiwavelength observations corroborate the multithermal nature of these counterstreaming flows: the cool H α component flows at about 10−20 km s −1 , while the warm ultraviolet and extreme-ultraviolet components reach 40–70 km s −1 . The Si iv 1400 Å line reveals significant microturbulence in the filament’s counterstreaming flows, with a nonthermal velocity width of ∼40 km s −1 . These multithermal flows emanate from compact brightenings at the filament’s ends, manifesting as small-scale, collimated upflows at their nascent phase. They continuously inject both chromospheric and transition region plasma into the filament channel, thereby feeding the counterstreaming flows. At their base, the Si iv and C ii spectral lines show pronounced line broadening and intensity enhancements, indicating significant localized chromospheric heating. Additionally, numerous small-scale photospheric flux emergence and cancellation events, with a magnitude of ∼10 17 Mx, are detected near their base. We suggest that such weak magnetic-field activities, possibly associated with unresolved magnetic reconnection events, drive these persistent upflows and localized footpoint heating. This work elucidates the multithermal origin of counterstreaming flows within a forming filament and provides evidence of localized chromospheric heating at the filament footpoints.}, archive = {J_ApJ}, author = {Hongrui Li and Hechao Chen and Chun Xia and Xiaoli Yan and Yongyuan Xiang and Jincheng Wang}, doi = {10.3847/1538-4357/adfc5e}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {37}, shortjournal = {The Astrophys. J.}, title = {Observational analysis of multithermal counterstreaming flows in a forming filament and their relationship with local heating at filament footpoints}, volume = {992}, year = {2025}, }
• (2025). Classifying metal-poor stars with machine learning using nucleosynthesis calculations. ApJ, 992(1), 36. (www)

  @article{ , abstract = {We apply the capabilities of machine learning (ML) to discern patterns in order to classify metal-poor stars. To do so, we train an ML model on a bank of nucleosynthesis calculations derived from hydrodynamic simulations for events such as neutron star mergers where the rapid ( r ) neutron capture process can take place. Likewise, we consider a bank of calculations from simulations of the slow ( s ) neutron capture process. We explore the performance of both a binary classifier and a one-class classifier. We demonstrate that our ML models do well overall in recognizing the s process from the r process, and after training on theoretical calculations, ML stellar assignments match conventional labels 87% of the time. We highlight that this method then points to stars that could benefit from additional observational measurements. We then apply the one-class classifier to numerous cases on which it did not train, including i -process stars, and a few nucleosynthesis predictions for the i process in rapidly accreting white dwarfs and r process in MHD supernovae. We demonstrate that the ML assigns some of the presently considered i -process stars to instead be of r or s in origin but likewise finds stars currently labeled as s to be potentially more aligned with i enrichment. This first application of ML to classify metal-poor star enrichment using theoretical nucleosynthesis calculations reveals the promise, and some challenges, associated with this new data-driven path forward.}, archive = {J_ApJ}, author = {Nicole Vassh and Yilin Wang and Richard M. Woloshyn and Michelle P. Kuchera and Maude Larivière and Kayle Majic and Benoit Côté}, doi = {10.3847/1538-4357/adfc6f}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {36}, shortjournal = {The Astrophys. J.}, title = {Classifying metal-poor stars with machine learning using nucleosynthesis calculations}, volume = {992}, year = {2025}, }
• (2025). Distinct acceleration relations of galaxies and galaxy clusters from hyperconical modified gravity. ApJ, 992(1), 35. (www)

  @article{ , abstract = {General relativity (GR) is the most successful theory of gravity, with great observational support on local scales. However, to keep GR valid over cosmic scales, some phenomena require the assumption of exotic dark matter, especially the cosmic expansion history and flat rotation curves of galaxies. Their radial acceleration relation (RAR) indicates a tight correlation between the dynamical mass and the baryonic mass. This suggests that galactic observations could be better explained by modified gravity theories without exotic matter. Modified Newtonian dynamics (MOND) is an alternative theory that was originally designed to do exactly this using a new fundamental acceleration scale, a 0 , the so-called Milgromian parameter. However, this nonrelativistic model lacks the flexibility needed to account for the wide variety of observed phenomena. In contrast, a relativistic MOND-like gravity naturally emerges from the hyperconical model, which derives a fictitious acceleration compatible with observations. We analyze the compatibility of the hyperconical model with respect to distinct RAR observations of 10 galaxy clusters obtained from HIFLUGCS and 60 high-quality SPARC galaxy rotation curves. The results show that a general relation can be fitted to most cases with only one or two parameters, with an acceptable χ 2 and p -value. These findings suggest a possible way to complete the proposed modification of GR on cosmic scales.}, archive = {J_ApJ}, author = {Robert Monjo and Indranil Banik}, doi = {10.3847/1538-4357/adfcc0}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {35}, shortjournal = {The Astrophys. J.}, title = {Distinct acceleration relations of galaxies and galaxy clusters from hyperconical modified gravity}, volume = {992}, year = {2025}, }
• (2025). Examining the radial evolution of a corotating interaction region observed at STEREO-A and MAVEN. ApJ, 992(1), 34. (www)

  @article{ , abstract = {Corotating interaction regions (CIRs) are long-lasting solar wind structures that persist over multiple solar rotations. These structures accelerate particles throughout the heliosphere and can impart significant energy onto planetary ionospheres and magnetospheres. Understanding how CIRs and their associated energetic particles evolve radially with heliocentric distance is of great interest and can give insight into acceleration mechanisms that occur within these structures. CIR solar wind and particle properties have been examined at numerous heliocentric distances but have been largely unexplored at Mars. We examine the properties of a CIR observed over two Carrington rotations by the Solar Terrestrial Relations Observatory (STEREO)-A at 1 au and the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft at 1.5 au. This CIR was observed during near-radial alignment of the spacecraft, allowing for the exclusion of significant longitudinal variations in the CIR’s properties. We find that during both rotations, the scaled solar wind density and interplanetary magnetic field are slightly higher at MAVEN than measurements at STEREO-A, and the CIR compression occurs over similar periods at both spacecraft during each event. Suprathermal particle enhancements are observed at both spacecraft during both passes of the CIR. Variations in the particle spectra between observations indicate suprathermal particle acceleration at both spacecraft, with higher-energy populations observed at 1.5 au compared to 1 au. Spectral anisotropies observed at MAVEN also indicate a combination of local and nonlocal particle acceleration, further demonstrating that the acceleration mechanisms associated with CIRs are complex and evolve with heliocentric distance.}, archive = {J_ApJ}, author = {Sarah A. Henderson and Rachael J. Filwett and Christina O. Lee and Rebecca Jolitz and Robert C. Allen and Maher A. Dayeh and Ali Rahmati and Davin Larson and Jasper S. Halekas and Jacob R. Gruesbeck and Antoinette Galvin and Hanying Wei and Bernd Heber}, doi = {10.3847/1538-4357/adfd55}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {34}, shortjournal = {The Astrophys. J.}, title = {Examining the radial evolution of a corotating interaction region observed at STEREO-A and MAVEN}, volume = {992}, year = {2025}, }
• (2025). Frequency-dependent evolution of propagating intensity disturbances in polar plumes. ApJ, 992(1), 33. (www)

  @article{ , abstract = {Quasiperiodic disturbances in EUV emission intensity, propagating along polar plumes in the solar corona, are frequently observed. Analysis of these propagating disturbances in the 171 Å bandpass of the Solar Dynamics Observatory/Atmospheric Imaging Assembly reveals that the wave spectrum evolves with height. Near the footpoints, the dominant spectral peak corresponds to oscillation periods of 12–15 minutes. As the disturbances propagate upward, the shorter-period spectral component diminishes, while a longer-period component of 20–30 minutes becomes dominant. Theoretical modeling of coronal slow magnetoacoustic waves effectively reproduces this spectral evolution. The model incorporates field-aligned thermal conduction and the back reaction of wave-induced perturbations on local thermal equilibrium. Coronal slow waves, driven by a broadband source with a peak at a shorter period, show a decrease in shorter-period spectral power with height, while the 20–30 minute spectral power increases due to thermal overstability. Analysis of the dispersion relations reveals that, given the chosen model parameters, the most rapidly growing spectral component corresponds to a 22.5 minute period, which aligns well with the observational findings.}, archive = {J_ApJ}, author = {Kyung-Suk Cho and Dmitrii Y. Kolotkov and Il-Hyun Cho and Valery M. Nakariakov}, doi = {10.3847/1538-4357/adfde0}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {33}, shortjournal = {The Astrophys. J.}, title = {Frequency-dependent evolution of propagating intensity disturbances in polar plumes}, volume = {992}, year = {2025}, }
• (2025). On the singularity structure of alfvénic turbulence. ApJ, 992(1), 32. (www)

  @article{ , abstract = {The singularity structure of the electromagnetic field fluctuations in strong Alfvénic turbulence is addressed. Owing to the transverse polarization of the fluctuations, the turbulent cascade is essentially perpendicular to the direction of the guiding magnetic field. A scaling analysis of the local energy transfer rates suggests that the most intense singularities are the sites of inertial dissipation of the energy. The lack of smoothness of the electromagnetic fields can give rise to dissipative processes unrelated to collisional transport phenomena in the magnetized plasma. A log-Poisson cascade model is developed. The random multiplicative cascade process is quantized and acts on the Elsässer field increments. In a multifractal interpretation, the log-Poisson cascade is characterized by three parameters: the most probable singularity strength, the strongest singularity, and its fractal codimension. The resulting probability distribution functions are derived from discrete superpositions of dilated integral scale distributions weighted by scale-dependent Poisson distributions. In addition to the three parameters mentioned above, they depend on the standard deviation of the integral scale fluctuations. The four-parameter family of normal log-Poisson mixture distributions is sensitive to the strongest singularities responsible for inertial dissipation of the electromagnetic energy in collisionless space plasma environments.}, archive = {J_ApJ}, author = {N. H. Bian and Gang Li}, doi = {10.3847/1538-4357/adfed5}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {32}, shortjournal = {The Astrophys. J.}, title = {On the singularity structure of alfvénic turbulence}, volume = {992}, year = {2025}, }
• (2025). Photospheric radius expansion thermonuclear burst and X-ray reflection from the neutron star X-ray binary 4U 1702-429. ApJ, 992(1), 31. (www)

  @article{ , abstract = {We perform a comprehensive study of thermonuclear bursts from the neutron star low-mass X-ray binary 4U 1702–429 detected with NICER and XMM-Newton. The thermonuclear burst detected with NICER shows clear evidence of a photospheric radius expansion (PRE) event and a distinct feature in the burst profile. The burst profiles demonstrate significant energy dependence, with the hardness ratio varying notably during the PRE phase. The radius of the neutron star photosphere expanded to a maximum of 23.{1}_{-3.2}^{+3.8} km while its temperature reached a minimum of ∼1.4 keV. The time-resolved burst spectra can be modeled using the variable persistent emission method, indicating that the soft excess may arise from enhanced mass accretion onto the neutron star, potentially due to the Poynting–Robertson drag. Alternatively, the disk reflection model can be used to explain the soft excess emission during a burst. The time-resolved spectral study is performed for three thermonuclear bursts detected with XMM-Newton. The XMM-Newton time-resolved burst spectra can be modeled using an absorbed blackbody model, without any signatures of the PRE. We conduct a detailed spectral analysis of the 2025 NuSTAR observation of 4U 1702–429, revealing a broad iron line at 6.4 keV and a Compton hump around 20 keV, indicating X-ray reflection features. The disk reflection model relxill provides an inner disk radius of ∼12 R g and an inclination angle of ∼39°. The magnetic field strength at the pole of the neutron star is estimated to be 5.1 × 10 8 G, assuming that the accretion disk is truncated at the magnetosphere boundary.}, archive = {J_ApJ}, author = {Manoj Mandal and Sachindra Naik and Gaurava Kumar Jaisawal}, doi = {10.3847/1538-4357/adff51}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {31}, shortjournal = {The Astrophys. J.}, title = {Photospheric radius expansion thermonuclear burst and X-ray reflection from the neutron star X-ray binary 4U 1702-429}, volume = {992}, year = {2025}, }
• (2025). The electron temperature distribution and the high ionization just behind the shock in the cygnus loop. ApJ, 992(1), 30. (www)

  @article{ , abstract = {The physical processes behind astrophysical collisionless shocks, such as thermal relaxation and ionization after shock passage, remain poorly understood. To investigate these processes, we analyze the northeastern region of the Cygnus Loop with XMM-Newton. The electron temperature is found to increase toward the interior of the remnant ranging from 0.15 to 0.19 keV energy range within a spatial scale of 6′ (or 1.27 pc at a distance of 725 pc) from the shock front. This can be explained well by a modified Sedov solution with radiative cooling. We also show that the ionization timescales determined from our spectroscopy are significantly larger than those estimated based on the electron density of the surrounding materials and the shock velocity. This excess can be qualitatively explained by a mixing of inner multiple plasma components with different ionization states due to turbulence.}, archive = {J_ApJ}, author = {Masahiro Ichihashi and Aya Bamba and Dai Tateishi and Kouichi Hagino and Satoru Katsuda and Hiroyuki Uchida and Hiromasa Suzuki and Ryo Yamazaki and Yutaka Ohira}, doi = {10.3847/1538-4357/ae058c}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {30}, shortjournal = {The Astrophys. J.}, title = {The electron temperature distribution and the high ionization just behind the shock in the cygnus loop}, volume = {992}, year = {2025}, }
• (2025). A search for chemical stratification and magnetic fields in eight field blue horizontal-branch stars*. ApJ, 992(1), 29. (www)

  @article{ , abstract = {In this article, we present the results of an analysis of chemical abundances and a search for magnetic fields in eight field blue horizontal-branch (BHB) stars: BD +01°0548, HD 74721, HD 86986, HD 87112, HD 93329, HD 109995, HD 161817, and HD 167105. This study is based on high-resolution optical spectra obtained with ESPaDOnS at the Canada–France–Hawaii Telescope. We first calculated the average chemical element abundance, the rotational velocity, and the radial velocity of the stars using the ZEEMAN2 spectrum synthesis code with the PHOENIX model atmospheres. We then studied the abundances of titanium and iron inferred from individual lines in the spectra of each star and their variations with their predicted formation depths τ 5000 . Similarly to the BHB stars cooler than 11,500 K observed in globular clusters, no clear observational evidence of vertical stratification is detected in the atmosphere of these stars. In the second part of this project, we searched for the presence of a magnetic field in the stars, applying the least-squares deconvolution technique on the Stokes I and V spectra. The measured mean longitudinal magnetic field uncertainties, ranging from 8 to 30 G, effectively rule out the presence of an organized magnetic field in these targets with a strength larger than a few 100 G.}, archive = {J_ApJ}, author = {Issouf Kafando and Gregg Wade and Alexandre David-Uraz and Francis LeBlanc and Carmelle Robert}, doi = {10.3847/1538-4357/ae060b}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {29}, shortjournal = {The Astrophys. J.}, title = {A search for chemical stratification and magnetic fields in eight field blue horizontal-branch stars*}, volume = {992}, year = {2025}, }
• (2025). Enceladus’s limit cycle. ApJ, 992(1), 28. (www)

  @article{ , abstract = {Enceladus exhibits some remarkable phenomena, including water geysers spraying through surface cracks, a global ice shell that is librating atop an ocean, a large luminosity, and rapid outward orbital migration. Here, we model the coupled evolution of Enceladus’s orbit and interior structure. We find that Enceladus is driven into a periodic state—a limit cycle. Many of Enceladus’s observed phenomena emerge from the model, and the predicted values for the orbital eccentricity, libration amplitude, shell thickness, and luminosity agree with observations. A single limit cycle lasts around 10 million years, and has three distinct stages: (1) freezing, (2) melting, and (3) resonant libration. In our model, Enceladus is currently in the freezing stage, meaning that its ice shell is getting thicker. That pressurizes the ocean, which in turn cracks the shell and pushes water up through the cracks. In this stage, the orbital eccentricity increases, as Saturn pushes Enceladus deeper into resonance with Dione. Once the eccentricity is sufficiently high, tidal heating begins to melt the shell, which is the second stage of the cycle. In the third stage, the shell remains close to 3 km thick. At that thickness, the shell’s natural libration frequency is resonant with the orbital frequency. The shell’s librations are consequently driven to large amplitude, for millions of years. Most of the tidal heating of Enceladus occurs during this stage, and the observed luminosity is a relic from the last episode of resonant libration, while the present-day heat production is small (∼1 GW).}, archive = {J_ApJ}, author = {Peter Goldreich and Yoram Lithwick and Jing Luan}, doi = {10.3847/1538-4357/adf8e7}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {28}, shortjournal = {The Astrophys. J.}, title = {Enceladus’s limit cycle}, volume = {992}, year = {2025}, }
• (2025). Observing supernova neutrino light curves with super-kamiokande. VI. a practical data analysis technique considering realistic experimental backgrounds. ApJ, 992(1), 27. (www)

  @article{ , abstract = {Neutrinos from supernovae, especially those emitted during the late phase of core collapse, are essential for understanding the final stages of massive star evolution. We have been dedicated to developing methods for the analysis of neutrinos emitted during the late phase and observed at Super-Kamiokande (SK). Our previous studies have successfully demonstrated the potential of various analysis methods in extracting essential physical properties; however, the lack of background consideration has limited their practical application. In this study, we address this issue by incorporating a realistic treatment of the experimental signal and background events with the on-going SK experiment. We therefore optimize our analysis framework to reflect realistic observational conditions, including both signal and background events. Using this framework we study several long-time supernova models, simulating the late phase neutrino observation in SK and focusing in particular on the identification of the last observed event. We discuss the possibility of model discrimination methods using timing information from this last observed event.}, archive = {J_ApJ}, author = {Fumi Nakanishi and Ken’ichiro Nakazato and Masayuki Harada and Yusuke Koshio and Ryuichiro Akaho and Yosuke Ashida and Akira Harada and Masamitsu Mori and Kohsuke Sumiyoshi and Yudai Suwa and Roger A. Wendell and Masamichi Zaizen}, doi = {10.3847/1538-4357/adfcca}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {27}, shortjournal = {The Astrophys. J.}, title = {Observing supernova neutrino light curves with super-kamiokande. VI. a practical data analysis technique considering realistic experimental backgrounds}, volume = {992}, year = {2025}, }
• (2025). Exploring the nature of little red dots: Constraints on active galactic nucleus and stellar contributions from PRIMER MIRI imaging. ApJ, 992(1), 26. (www)

  @article{ , abstract = {JWST has revealed a large population of compact, red objects at z > 4 known as Little Red Dots (LRDs). We analyze the spectral energy distributions (SEDs) of 88 LRDs from the JWST PRIMER survey with complete photometric coverage from 1 to 18 μ m using NIRCam and MIRI imaging, representing the most extensive SED analysis on a large LRD sample with long-wavelength MIRI data. We examine SED models in which either galaxy or active galactic nucleus (AGN) emission dominates the rest-frame UV or optical continuum, extracting physical properties to explore each scenario’s implications. In the galaxy-only model, we find massive, dusty stellar populations alongside unobscured, low-mass components, hinting at inhomogeneous obscuration. The AGN-only model indicates dusty, luminous AGNs with low hot dust fractions compared to typical quasars. A hybrid AGN and galaxy model suggests low-mass, unobscured galaxies in the UV, with stellar mass estimates spanning ∼2 dex across the different models, underscoring the need for caution in interpreting LRD stellar masses. With MIRI photometry, the galaxy-only model produces stellar masses within cosmological limits, but extremely high stellar mass densities are inferred. The hybrid model infers highly overmassive black holes exceeding those in recently reported high-redshift AGNs, hinting at a partial AGN contribution to the rest-optical continuum or widespread super-Eddington accretion. Our findings highlight the extreme conditions required for both AGN- and galaxy-dominated scenarios in LRDs, supporting a mixed contribution to the red continuum, or novel scenarios to explain the observed emission.}, archive = {J_ApJ}, author = {Gene C. K. Leung and Steven L. Finkelstein and Pablo G. Pérez-González and Alexa M. Morales and Anthony J. Taylor and Guillermo Barro and Dale D. Kocevski and Hollis B. Akins and Adam C. Carnall and Óscar A. Chávez Ortiz and Nikko J. Cleri and Fergus Cullen and Callum T. Donnan and James S. Dunlop and Richard S. Ellis and Norman A. Grogin and Michaela Hirschmann and Anton M. Koekemoer and Vasily Kokorev and Ray A. Lucas and Derek J. McLeod and Casey Papovich and L. Y. Aaron Yung}, doi = {10.3847/1538-4357/adfcce}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {26}, shortjournal = {The Astrophys. J.}, title = {Exploring the nature of little red dots: Constraints on active galactic nucleus and stellar contributions from PRIMER MIRI imaging}, volume = {992}, year = {2025}, }
• (2025). The dust echo emission of fast blue optical transients and application to the near-infrared excess of AT 2018cow. ApJ, 992(1), 25. (www)

  @article{ , abstract = {A near-infrared (NIR) excess has been discovered in the emission of the representative fast blue optical transient (FBOT) AT 2018cow. It was suggested that this NIR excess could be emitted by the dust surrounding the source and thus could provide a probe into the nature of its progenitor. We develop a model to describe the influence of the FBOT emission on the environmental dust, and as a result, a dust-free evaporation cavity can be formed on a timescale of 1 day. Outside this cavity, the surviving dust grains can have different size distributions at different distances from the source. With such a special dust environment, we fit the multiwavelength light curves of AT 2018cow by taking into account the evolutionary dust echo of the FBOT emission. It is found that the dust temperature can vary with time along with the evolution of the irradiating FBOT emission. Even at a fixed time, the dust temperature can be distributed in a wide range rather than having only a unique value. Furthermore, both the mass of the dust shell and its distance to the FBOT are found to be much larger than those derived with a direct empirical fitting of the NIR spectra but without considering the evolutionary relationship between the spectra.}, archive = {J_ApJ}, author = {Jing-Yao Li and Yun-Wei Yu and Liang-Duan Liu and Ming-Yan Xiao}, doi = {10.3847/1538-4357/ae03bb}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {25}, shortjournal = {The Astrophys. J.}, title = {The dust echo emission of fast blue optical transients and application to the near-infrared excess of AT 2018cow}, volume = {992}, year = {2025}, }
• (2025). Simultaneous ion arrival times during the rise phase of 3He-rich solar energetic particle events. ApJ, 992(1), 24. (www)

  @article{ , abstract = {We have investigated the arrival times of species H–Fe in 3 He-rich solar energetic particle (SEP) events to determine if a common acceleration mechanism is responsible for all the ions, assuming that if the particles arrive simultaneously this is evidence of a common mechanism. Compared to other SEP populations, the extremely large enrichment of 3 He and much smaller though significant heavy ion enhancements suggest a common origin but without firm observational evidence due to the small size of the events. Using improved instruments close to the Sun on Solar Orbiter, we surveyed the period 2020 April—2025 May for 3 He-rich events whose rise phase phases were sufficiently undistorted and intense that the particle arrival times could be measured accurately. We found six events that met the criteria and that appear to be typical impulsive SEP events but with unusually high counting statistics. For C–Fe the mean arrival times of 226–320 keV nucleon −1 ions are simultaneous to ∼5 minutes, a small fraction of the ion propagation time from the Sun (110–310 minutes depending on heliocentric distance). H and 4 He mean arrival times showed a maximum difference of 1.6 minutes. Overall 3 He arrival times differ from the others by ∼3 ± 3 minutes. These times are sufficiently close to simultaneity to give evidence for a common acceleration mechanism. This adds a new constraint to models for these events, namely, that the accelerating waves can interact with the broad range of gyrofrequencies associated with the range charge-to-mass ratios for H–Fe.}, archive = {J_ApJ}, author = {G. M. Mason and A. Kouloumvakos and G. C. Ho and R. C. Allen and R. Gómez-Herrero and I. Cernuda and R. F. Wimmer-Schweingruber and J. Rodríguez-Pacheco}, doi = {10.3847/1538-4357/ae0626}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {24}, shortjournal = {The Astrophys. J.}, title = {Simultaneous ion arrival times during the rise phase of 3He-rich solar energetic particle events}, volume = {992}, year = {2025}, }
• (2025). MC-BLOS: Automated software for determining the line-of-sight component of magnetic fields associated with molecular clouds∗. ApJ, 992(1), 23. (www)

  @article{ , abstract = {While plane-of-sky magnetic field observations in molecular clouds are now common, observations of their line-of-sight magnetic field remain limited. To address this issue, M. Tahani et al. developed a technique based on Faraday rotation. The technique incorporates an ON–OFF approach to identify the rotation measure induced by the magnetic fields associated with the cloud. The upcoming abundance of observations of Faraday rotation from the Square Kilometre Array and its pathfinders necessitates robustly tested software to automatically obtain line-of-sight magnetic fields of molecular clouds. We developed software, called MC-BLOS (for molecular cloud line-of-sight magnetic field; DOI:10.5281/zenodo.15338512), to carry out the technique in an automated manner. The software’s inputs are Faraday rotation of point sources, maps of extinction or column density, results from chemical evolution code, and a parameter file that allows the user to specify the cloud name or other parameters pertaining to the technique. For each cloud, the software invokes a set of predefined initial parameters such as density, temperature, and surrounding boundary, which the user can modify. The software then runs the technique automatically, outputting line-of-sight magnetic field maps and tables (including uncertainties) at the end of the process. MC-BLOS generates diagnostic files for result evaluation and input parameter refinement, allowing for expert judgment in parameter selection. We have tested the software on previously published clouds, and the results are consistent within the reported uncertainty range. This software will facilitate the analysis of forthcoming observations of Faraday rotation, enabling a better understanding of the role of magnetic fields in molecular cloud dynamics and star formation.}, archive = {J_ApJ}, author = {Mehrnoosh Tahani and John Ming Ngo and Jennifer Glover and Ryan Clairmont and Gabriel M. Zarazua and René Plume}, doi = {10.3847/1538-4357/add410}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {23}, shortjournal = {The Astrophys. J.}, title = {MC-BLOS: Automated software for determining the line-of-sight component of magnetic fields associated with molecular clouds∗}, volume = {992}, year = {2025}, }
• (2025). Study of the IC 443 region with the HAWC observatory. ApJ, 992(1), 22. (www)

  @article{ , abstract = {Supernova remnants are one potential source class considered a PeVatron (i.e., capable of accelerating cosmic rays above PeV energies). The shock fronts produced after the explosion of the supernova are ideal regions for particle acceleration. IC 443 is a supernova remnant that has been studied extensively at different wavelengths. Using 2966 days of gamma-ray data from the High Altitude Water Cherenkov (HAWC) observatory, we study the emission of IC 443 with the objective of finding signatures of cosmic-ray acceleration at the PeV scale. Using a maximum likelihood method, we find a point source located at ( α = 94 \mathop{.}\limits^{\unicode{x000b0}} 42, δ = 22 \mathop{.}\limits^{\unicode{x000b0}} 35) that we associate with IC 443. The measured spectrum is a simple power law with an index of −3.14 ± 0.18, which is consistent with previous TeV observations. Although we cannot confirm that IC 443 is a hadronic PeVatron, we do not find any sign that the spectrum has a cutoff at tens of TeV energies, with the spectrum extending to ∼30 TeV. Furthermore, we also find a new extended component in the region whose emission is described by a simple power law with an index of −2.49 ± 0.08 and which we call HAWC J0615+2213. While we show evidence that this new source might be a new TeV halo, we defer a detailed analysis of this new source to another publication.}, archive = {J_ApJ}, author = {R. Alfaro and C. Alvarez and M. Araya and J. C. Arteaga-Velázquez and D. Avila Rojas and H. A. Ayala Solares and R. Babu and P. Bangale and A. Bernal and K. S. Caballero-Mora and T. Capistran and A. Carramiñana and S. Casanova and U. Cotti and J. Cotzomi and S. Coutiño de León and E. De la Fuente and D. Depaoli and P. Desiati and N. Di Lalla and R. Diaz Hernandez and B. L. Dingus and M. A. DuVernois and J. C. Díaz-Vélez and T. Ergin and C. Espinoza and K. Fang and N. Fraija and S. Fraija and J. A. García-González and H. Goksu and J. A. González-Cervera and M. M. González and J. A. Goodman and S. Groetsch and J. P. Harding and S. Hernández-Cadena and I. Herzog and J. Hinton and D. Huang and F. Hueyotl-Zahuantitla and P. Hüntemeyer and S. Kaufmann and A. Lara and J. Lee and H. León Vargas and J. T. Linnemann and A. L. Longinotti and G. Luis-Raya and K. Malone and O. Martinez and J. Martínez-Castro and J. A. Matthews and P. Miranda-Romagnoli and J. A. Montes and J. A. Morales-Soto and E. Moreno and M. Mostafá and M. Najafi and L. Nellen and M. U. Nisa and R. Noriega-Papaqui and L. Olivera-Nieto and N. Omodei and M. Osorio and E. Ponce and Y. Pérez Araujo and E. G. Pérez-Pérez and C. D. Rho and D. Rosa-González and M. Roth and E. Ruiz-Velasco and H. Salazar and A. Sandoval and M. Schneider and G. Schwefer and J. Serna-Franco and A. J. Smith and Y. Son and R. W. Springer and O. Tibolla and K. Tollefson and I. Torres and R. Torres-Escobedo and R. Turner and X. Wang and Z. Wang and I. J. Watson and H. Wu and S. Yu and S. Yun-Cárcamo and H. Zhou and C. de León and (HAWC Collaboration)}, doi = {10.3847/1538-4357/adf7aa}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {22}, shortjournal = {The Astrophys. J.}, title = {Study of the IC 443 region with the HAWC observatory}, volume = {992}, year = {2025}, }
• (2025). Halo occupation distribution of quasars: Dependence on luminosity, redshift, black hole mass and feedback modes. ApJ, 992(1), 21. (www)

  @article{ , abstract = {We use cosmological hydrodynamic simulations (IllustrisTNG and SIMBA) to explore the redshift, luminosity, and black hole mass dependence of the quasar halo occupation distribution (HOD). In both simulations, we find that the quasar activity is quenched at a characteristic halo mass (∼10 13 M ⊙ ) scale affecting the nature of its occupation distribution function. We note that the quenching is more pronounced at low redshifts for quasars selected through a luminosity threshold. We show that a very significant bias (a factor of ∼10–50 in the central occupation and ∼10%–70% in the satellite occupation fraction) is introduced in the reconstruction of quasar host halo mass distributions from the observed two-point-correlation function, if the HOD modeling does not account for the quenching effect in the central occupation function. While there is strong suppression of the occupation fraction of central quasars, the satellite occupation still follows a power-law-like behavior. Our results show that the global satellite fraction of quasars increases monotonically from high to low redshifts, with 20%–40% of the quasars being satellite at intermediate redshifts, consistent with previous clustering-based estimates. In addition, our study reveals that while the occupation function of quasars depends on redshift, luminosity, and feedback modes, there is hardly any evolution in the supermassive black hole (SMBH; mass-selected sample) occupation. The SMBH HOD over the entire parameter space is well modeled by a power-law and a step function similar to what has been found for galaxies and low-luminosity active galactic nuclei.}, archive = {J_ApJ}, author = {Anirban Chowdhary and Suchetana Chatterjee}, doi = {10.3847/1538-4357/adfb6d}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {21}, shortjournal = {The Astrophys. J.}, title = {Halo occupation distribution of quasars: Dependence on luminosity, redshift, black hole mass and feedback modes}, volume = {992}, year = {2025}, }
• (2025). TransFit: An efficient framework for transient light-curve fitting with time-dependent radiative diffusion. ApJ, 992(1), 20. (www)

  @article{ , abstract = {Modeling the light curves (LCs) of luminous astronomical transients, such as supernovae, is crucial for understanding their progenitor physics, particularly with the exponential growth of survey data. However, existing methods face limitations: efficient semianalytical models (e.g., Arnett-like) employ significant physical simplifications (like time-invariant temperature profiles and simplified heating distributions), often compromising accuracy, especially for early-time LCs. Conversely, detailed numerical radiative transfer simulations, while accurate, are computationally prohibitive for large data sets. This paper introduces TransFit , a novel framework that numerically solves a generalized energy conservation equation, explicitly incorporating time-dependent radiative diffusion, continuous radioactive or central engine heating, and ejecta expansion dynamics. The model accurately captures the influence of key ejecta properties and diverse heating source characteristics on LC morphology, including peak luminosity, rise time, and overall shape. Furthermore, TransFit provides self-consistent modeling of the transition from shock-cooling to 56 Ni-powered LCs. By combining physical realism with computational speed, TransFit provides a powerful tool for efficiently inverting LCs and extracting detailed physical insights from the vast data sets of current and future transient surveys.}, archive = {J_ApJ}, author = {Liang-Duan Liu and Yu-Hao Zhang and Yun-Wei Yu and Ze-Xin Du and Jing-Yao Li and Guang-Lei Wu and Zi-Gao Dai}, doi = {10.3847/1538-4357/adfed6}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {20}, shortjournal = {The Astrophys. J.}, title = {TransFit: An efficient framework for transient light-curve fitting with time-dependent radiative diffusion}, volume = {992}, year = {2025}, }
• (2025). Nebular spectra of kilonovae with detailed recombination rates. i. light r-process composition. ApJ, 992(1), 19. (www)

  @article{ , abstract = {To investigate spectra of kilonovae in the nonlocal thermal equilibrium phase ( t ≳ 1 week), we perform atomic calculations for dielectronic recombination (DR) rates for the light r -process elements Se ( Z = 34), Rb ( Z = 37), Sr ( Z = 38), Y ( Z = 39), and Zr ( Z = 40) using the HULLAC code. For the different elements, our results for the DR rate coefficients for recombining from the ionization states of II to I, III to II, and IV to III vary between 2 × 10 −12 –5 × 10 −11 cm 3 s −1 , 10 −13 –5 × 10 −11 cm 3 s −1 , and 2 × 10 −15 –10 −11 cm 3 s −1 , respectively, at a temperature of T = 10,000 K. Using this new atomic data (DR), we study the impact on kilonova model spectra at phases of t = 10 days and t = 25 days after the merger using the spectral synthesis code SUMO . Compared to models using the previous treatment of recombination as a constant rate, the new models show significant changes in ionization and temperature, and, correspondingly, in emergent spectra. With the new rates, we find that Zr ( Z = 40) plays a yet more dominant role in kilonova spectra for light r -process compositions. Furthermore, we show that previously predicted mid-infrared (e.g., [Se III ] 4.55 μ m) and optical (e.g., Rb I 7802, 7949 Å) lines weaken in the new model. Instead, [Se I ] 5.03 μ m emerges as a signature. These results demonstrate the importance of considering the detailed microphysics for modelling and interpreting the late-time kilonova spectra.}, archive = {J_ApJ}, author = {Smaranika Banerjee and Anders Jerkstrand and Nigel Badnell and Quentin Pognan and Niamh Ferguson and Jon Grumer}, doi = {10.3847/1538-4357/adf6ba}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {19}, shortjournal = {The Astrophys. J.}, title = {Nebular spectra of kilonovae with detailed recombination rates. i. light r-process composition}, volume = {992}, year = {2025}, }
• (2025). Early planet formation in embedded disks (eDisk). XXII. keplerian disk, disk structures, and Jets/Outflows in the class 0 protostar IRAS 04166+2706. ApJ, 992(1), 18. (www)

  @article{ , abstract = {We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of the Class 0 protostar IRAS 04166+2706, obtained as part of the ALMA Large Program Early Planet Formation in Embedded Disks. These observations were made in the 1.3 mm dust continuum and molecular lines at angular resolutions of \sim 0\mathop{.}\limits{^{\prime\prime} }05 (∼8 au) and \sim 0\mathop{.}\limits{^{\prime\prime} }16 (∼25 au), respectively. The continuum emission shows a disklike structure with a radius of ∼22 au. Kinematical analysis of 13 CO (2–1), C 18 O (2–1), H 2 CO (3 0,3 –2 0,2 ), CH 3 OH (4 2 –3 1 ) emission demonstrates that these molecular lines trace the infalling-rotating envelope and possibly a Keplerian disk, enabling us to estimate the protostar mass to be 0.15 M ⊙ < M ⋆ < 0.39 M ⊙ . The dusty disk is found to exhibit a brightness asymmetry along its minor axis in the continuum emission, probably caused by a flared distribution of the dust and the high optical depth of the dust emission. In addition, the 12 CO (2–1) and SiO (5–4) emissions show knotty and wiggling motions in the jets. Our high-angular-resolution observations revealed the most recent mass ejection events, which have occurred within the last ∼25 yr.}, archive = {J_ApJ}, author = {Nguyen Thi Phuong and Chang Won Lee and John J. Tobin and Nagayoshi Ohashi and Jes K. Jørgensen and Shigehisa Takakuwa and Yuri Aikawa and Yusuke Aso and Zhi-Yun Li and Patrick M. Koch and Jonathan P. Williams and Sacha Gavino and Zhe-Yu Daniel Lin and Kengo Tomida and Woojin Kwon and Leslie W. Looney and Ilseung Han and Alejandro Santamaría-Miranda and Shih-Ping Lai and Hsi-Wei Yen and Travis J. Thieme and Jinshi Sai and Christian Flores}, doi = {10.3847/1538-4357/adfa92}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {18}, shortjournal = {The Astrophys. J.}, title = {Early planet formation in embedded disks (eDisk). XXII. keplerian disk, disk structures, and Jets/Outflows in the class 0 protostar IRAS 04166+2706}, volume = {992}, year = {2025}, }
• (2025). A galactic interloper: A study of the camelopardis OB1 association’s clusters and its visitor from the perseus arm. ApJ, 992(1), 17. (www)

  @article{ , abstract = {Within the molecular clouds of the Camelopardis OB1 (Cam OB1) association exists a region previously noted as one subgroup. However, bulk clustering from Gaia astrometry has recently shown three distinctive kinematically coherent groups, all found in a similar location in the sky (137 ⪅ l ⪅ 145 and −2 ⪅ b ⪅ 5) and at a similar distance (∼1 kpc). In this work, we derive from first principles the three proposed clusters in this region, refine the membership list and cluster ages, and, for the first time, examine the 3D structure, motion, and origin of the clusters. Using clustering of Gaia data in 3D position + 2D velocity space, supplemented by available fifth-generation Sloan Digital Sky Survey radial velocities, we find clusters of ages 10, 15.8, and 20 Myr with members numbering 140, 469, and 184, respectively. All three clusters overlap currently in 3D space. Tracing their previous locations, based on present-day motions, shows that each cluster originated in its own distinct region and exhibited no influence on each other’s formation. Two of the clusters trace their origin to different areas within the Cam OB1 association, with the oldest cluster tracing its origins to the near edge of the Perseus Arm, in the direction of the Perseus OB1 or Cassiopeia OB6 associations. Overall, this work illustrates how different stellar groups, even those originating in a different spiral arm, can visit and pass through each other as they travel through the Galaxy.}, archive = {J_ApJ}, author = {Joseph Mullen and Amanda Mast and Marina Kounkel and Keivan Stassun and Alexandre Roman-Lopes and Jonathan C. Tan}, doi = {10.3847/1538-4357/adfb7a}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {17}, shortjournal = {The Astrophys. J.}, title = {A galactic interloper: A study of the camelopardis OB1 association’s clusters and its visitor from the perseus arm}, volume = {992}, year = {2025}, }
• (2025). Massive double white dwarf binary mergers from the moon: Extending the reach of multimessenger astrophysics. ApJ, 992(1), 16. (www)

  @article{ , abstract = {We explore the potential of lunar-based gravitational-wave detectors to broaden the multimessenger astrophysics landscape by detecting mergers of massive ( M 1 , M 2 > 1 M ⊙ ) double white dwarf (WD) binaries. These systems are potential progenitors of Type Ia supernovae and could serve as independent probes of cosmic expansion. We examine two proposed lunar gravitational-wave detector concepts operating in the subhertz band (0.1–1 Hz): the Gravitational-Wave Lunar Observatory for Cosmology (a proxy for suspended test mass detectors) and the Lunar Gravitational-Wave Antenna (a proxy for seismic array detectors). We estimate that these detectors could reach distances of up to ∼1 Gpc for the most massive mergers. We show that lunar detectors could observe up to dozens of massive WD mergers annually, including those originating from globular clusters. Lunar detectors would constrain the masses of these WDs with an unprecedented accuracy of one part in a million. Furthermore, these detectors would provide early warnings weeks before mergers, including sky-localization of square arcminute resolution, enabling a new era of coordinated multimessenger follow-up of electromagnetic transients—whether they evolve into Type Ia supernovae or accretion-induced collapse events.}, archive = {J_ApJ}, author = {Manuel Pichardo Marcano and Anjali B. Yelikar and Karan Jani}, doi = {10.3847/1538-4357/adfc48}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {16}, shortjournal = {The Astrophys. J.}, title = {Massive double white dwarf binary mergers from the moon: Extending the reach of multimessenger astrophysics}, volume = {992}, year = {2025}, }
• (2025). High-resolution simulations of the interaction between the Nova/Supernova ejecta and the accretion disk. ApJ, 992(1), 15. (www)

  @article{ , abstract = {Many nova and Type Ia supernova (SN Ia) explosion scenarios involve accretion disks. However, direct numerical simulations of these explosive phenomena have barely addressed the question of the impact of ejecta−disk collision on the midterm evolution of such explosions. This is particularly critical for a better understanding of classical and recurrent novae, where each nova cycle depends on the imprint left by the precedent explosion. In this work, we describe and analyze a set of high-resolution simulations of the ejecta−disk interaction. We show that, depending on the initial configuration of the binary system, the disk is partially or, more often, totally destroyed, which will impact the next nova explosion cycle. In the case of SNe Ia, the much larger kinetic energy carried by the ejecta always provokes complete destruction of the accretion disk. We also discuss the alterations induced in the geometry of the ejecta by the shielding effect of the disk, which has been shown to cause reduced contamination of the companion star up to a factor ∼1.5–2 in key nuclei produced during the nova outburst. In the framework of recurrent nova simulations, we report for the first time on the formation of a cavity in the ejecta after its interaction with the disk. We also describe the onset and development of several hydrodynamic instabilities such as Kelvin–Helmholtz and Richtmyer–Meshkov.}, archive = {J_ApJ}, author = {Axel S. Lechuga and Domingo García-Senz and Jordi José}, doi = {10.3847/1538-4357/adfc5f}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {15}, shortjournal = {The Astrophys. J.}, title = {High-resolution simulations of the interaction between the Nova/Supernova ejecta and the accretion disk}, volume = {992}, year = {2025}, }
• (2025). Three-dimensional polarimetric structure of jets from radio galaxy MRC 0600–399 in a3376. ApJ, 992(1), 14. (www)

  @article{ , abstract = {MRC 0600–399, in the merging galaxy cluster A3376, is one of the unique head–tail radio galaxies that have abruptly bending structures, the origin of which is still under discussion. A previous study suggested that the interaction between the jets and the magnetic fields on the cold front has produced such an outstanding feature; however, it is still not known how the jet propagates such a long distance while keeping its sharp shape. In this study, we performed a polarization analysis of MRC 0600–399 and a nearby radio source using MeerKAT L -band data. To interpret the Faraday structure, we constructed a pseudo-3D visualization map of the reconstructed 3D cube of the Faraday dispersion function. MRC 0600–399 has a complicated Faraday depth structure, and some of the Faraday depth features are in good agreement with the 2D structure on the celestial sphere. For the northern jet of MRC 0600–399, the Faraday depth values show a clear gap at the tip region. Based on the polarization analysis and comparison with other observations, we concluded that the synchrotron radiation from the tip region of the northern jet originates from the magnetic field on the cold front.}, archive = {J_ApJ}, author = {Haruka Sakemi and James O. Chibueze and William D. Cotton and Viral Parekh and Takumi Ohmura and Mami Machida and Taichi Igarashi and Takuya Akahori and Hiroki Akamatsu and Hiroyuki Nakanishi and Tsutomu T. Takeuchi}, doi = {10.3847/1538-4357/adfc64}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {14}, shortjournal = {The Astrophys. J.}, title = {Three-dimensional polarimetric structure of jets from radio galaxy MRC 0600–399 in a3376}, volume = {992}, year = {2025}, }
• (2025). Stars born in the wind: M82’s outflow and halo star formation. ApJ, 992(1), 13. (www)

  @article{ , abstract = {Starburst galaxies, such as M82, launch kiloparsec-scale galactic outflows that interact with the circumgalactic medium (CGM) in complex ways. Apart from enriching the CGM with metals and energy, these outflows may trigger star formation in the halo—either by driving shocks into the CGM or transporting cold, star-forming gas. To investigate such processes, we analyze the star formation history (SFH) of the Southern Arcs—arc-like stellar features located ∼5 kpc from M82’s star-forming disk along the minor axis—using Hubble Space Telescope Wide Field Camera 3 photometry. From resolved stellar populations, we derive SFHs over the last ∼500 Myr, finding that ∼85% of the stellar mass formed between ∼150 and ∼70 Myr ago, followed by a brief pause, with the remaining ∼15% forming since ∼30 Myr ago. The two stellar populations are cospatial on scales of at least ∼200 pc. The timing of the ∼100 Myr burst aligns with star formation in the M82 disk and the age distribution of its star clusters, suggesting a causal link between the disk starburst and halo star formation. We explore two mechanisms that could explain these observations. In the first, shocks driven by the interaction between hot outflowing gas and cooler CGM material compress dense clouds, triggering collapse and star formation. In the second, stars form directly within massive, cool clouds associated with the outflow. As these clouds move ballistically through the halo, subsequent interactions with tidal debris may trigger additional star formation, producing the observed episodic structure.}, archive = {J_ApJ}, author = {Vaishnav V. Rao and Adam Smercina and Eric F. Bell and Benjamin Williams and Julianne J. Dalcanton and Andrew Dolphin and Adam Leroy and Antonela Monachesi and Jeremy Bailin and Roelof S. de Jong and Fabian Walter}, doi = {10.3847/1538-4357/adfdce}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {13}, shortjournal = {The Astrophys. J.}, title = {Stars born in the wind: M82’s outflow and halo star formation}, volume = {992}, year = {2025}, }
• (2025). Chondrule dust rim growth: Influence of restructuring using molecular dynamics simulations. ApJ, 992(1), 12. (www)

  @article{ , abstract = {We investigate the influence of disruptive collisions on chondrule rim growth, emphasizing the role of kinetic energy in determining the outcomes of these interactions. We establish a threshold of approximately 10 cm s −1 for the “hit-and-stick” collision regime, beyond which significant changes occur in the structure of rimmed chondrules. Our findings highlight that at low collision energies (KE < 10 −12 J), minimal structural alteration takes place, while higher energies (KE up to 10 −10 J) lead to compaction of the rim, reducing both its thickness and porosity. Collisions with energies exceeding 10 −8 J result in the complete disruption of the rim, with particles being expelled from it. These results are correlated with the turbulence levels within the disk, as kinetic energy scales with the relative velocities of colliding particles. Leveraging machine learning models trained on our collision data, we predict changes in rim characteristics and employ these predictions in a Monte Carlo simulation to explore rim growth dynamics. Our simulations reveal that rim development is sustained in low-turbulence environments ( α ≤ 10 −5 ), while intermediate turbulence levels ( α = 10 −3 –10 −4 ) lead to erosion, preventing further rim accumulation in high-turbulence contexts.}, archive = {J_ApJ}, author = {Chuchu Xiang and Nina Merkert (Née Gunkelmann) and Lorin S. Matthews and Augusto Carballido and Truell W. Hyde}, doi = {10.3847/1538-4357/adfeca}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {12}, shortjournal = {The Astrophys. J.}, title = {Chondrule dust rim growth: Influence of restructuring using molecular dynamics simulations}, volume = {992}, year = {2025}, }
• (2025). Diffusion of relativistic charged particles and field lines in isotropic turbulence. II. analytical models. ApJ, 992(1), 11. (www)

  @article{ , abstract = {The transport of high-energy particles in the presence of small-scale, turbulent magnetic fields is a long-standing issue in astrophysics. Analytical theories on transport perpendicular to the large-scale magnetic field disagree with numerical simulations at rigidities where the particles’ gyroradii are slightly smaller than the correlation length of turbulence. At the same time, extending the numerical simulations to lower rigidities has proven computationally prohibitive. We present an analytical model for the perpendicular transport, based on (1) initial particle transport along field lines, (2) the transport of field lines, and (3) the eventual decorrelation of particles from field lines. Transport parallel to the large-scale field is governed by pitch-angle scattering, and so for times larger than the inverse pitch-angle diffusion coefficient, particles spatially diffuse in the parallel direction. Our results suggest that perpendicular diffusion occurs when particles have displaced in the perpendicular direction by a few correlation lengths of turbulence. We have tested the analytical theory by running a large suite of test particle simulations at unprecedentedly low rigidities, making extensive use of graphical processing units. Our numerical results exhibit a nonstandard rigidity dependence for the perpendicular diffusion coefficient at intermediate rigidities. At the lowest rigidities, the standard rigidity dependence is recovered. The simulated diffusion coefficients are nicely reproduced by our analytical model. We have traced the nonstandard rigidity dependence to a subdiffusive phase in the field line transport. Our study confirms our understanding of the escape of cosmic rays from the Galactic halo and its rigidity dependence. It also rejects speculations about different rigidity dependencies of the parallel and perpendicular diffusion coefficients at very low rigidities that were invoked to explain nonstandard gamma-ray spectra from the Galactic center. Other possible applications concern particle acceleration at perpendicular shocks.}, archive = {J_ApJ}, author = {Marco Kuhlen and Philipp Mertsch and Vo Hong Minh Phan}, doi = {10.3847/1538-4357/adee94}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {11}, shortjournal = {The Astrophys. J.}, title = {Diffusion of relativistic charged particles and field lines in isotropic turbulence. II. analytical models}, volume = {992}, year = {2025}, }
• (2025). Diffusion of relativistic charged particles and field lines in isotropic turbulence. i. numerical simulations. ApJ, 992(1), 10. (www)

  @article{ , abstract = {The transport of nonthermal particles across a large-scale magnetic field in the presence of magnetized turbulence has been a long-standing issue in high-energy astrophysics. Of particular interest is the dependence of the parallel and perpendicular mean free paths λ ∥ and λ ⊥ on rigidity { \mathcal R } . We have revisited this important issue with a view to applications from the transport of Galactic cosmic rays (CRs) to acceleration at astrophysical shocks. We have run test particle simulations of CR transport in synthetic, isotropic Kolmogorov turbulence at unprecedentedly low reduced rigidities of r g / L c ≃ 10 −4 , corresponding to { \mathcal R }\simeq 10\,\,\rm{TV}\, for a turbulent magnetic field of B rms = 4 μ G and correlation length of L c = 30 pc. Extracting the (asymptotic) parallel and perpendicular mean free paths λ ∥ and λ ⊥ , we have found {\lambda }_{\parallel }\propto {({r}_{\rm{g}\,}/{L}_{\,\rm{c}})}^{1/3} as expected for a Kolmogorov turbulence spectrum. In contrast, λ ⊥ has a faster dependence on r g / L c for 10 −2 ≲ r g / L c ≲ 1, but for r g / L c ≪ 10 −2 , {\lambda }_{\perp }\propto {({r}_{\rm{g}\,}/{L}_{\,\rm{c}})}^{1/3} . Our results have important implications for the transport of Galactic CRs.}, archive = {J_ApJ}, author = {Marco Kuhlen and Philipp Mertsch and Vo Hong Minh Phan}, doi = {10.3847/1538-4357/adee9a}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {10}, shortjournal = {The Astrophys. J.}, title = {Diffusion of relativistic charged particles and field lines in isotropic turbulence. i. numerical simulations}, volume = {992}, year = {2025}, }
• (2025). SN 2019tsf: Evidence for extended hydrogen-poor CSM in the three-peaked light curve of stripped envelope of a type ib supernova. ApJ, 992(1), 9. (www)

  @article{ , abstract = {We present multiband ATLAS and ZTF photometry for SN 2019tsf, a Type Ib stripped-envelope supernova (SESN). The slow spectral evolution could be associated with an uncommon explosion mechanism specific to this SN. Possible explanations include fallback accretion onto a compact remnant or a long-lived central engine, both of which could provide extended energy injection responsible for the late-time rebrightening and unusual spectral features. The rebrightening observations represent the latest photometric measurements of a multipeaked Type Ib SN. As late-time photometry and spectroscopy suggest no hydrogen, the potential circumstellar material (CSM) must be H-poor. The absence of a nebular phase and the lack of narrow emission lines in the late-time spectra (>142 days) of the SNe suggest that any CSM interaction is likely asymmetric and enveloped by the SN ejecta. However, an extended CSM structure is evident through a follow-up radio campaign with the Karl G. Jansky Very Large Array (VLA), indicating a source of bright optically thick radio emission at late times, which is highly unusual among H-poor SESNe. We attribute this phenomenology to an interaction of the supernova ejecta with asymmetric CSM, potentially disk-like, and we present several models that may explain the origin of this rare Type Ib supernova. We propose a warped disk model in which a tertiary companion—commonly present around massive stars—perturbs the progenitor’s CSM, producing density enhancements that may explain the observed multipeaked SN 2019tsf light curve. This SN 2019tsf is a unique SN Type Ib among the recently discovered class of SNe that undergo mass transfer at the moment of explosion.}, archive = {J_ApJ}, author = {Yossef Zenati and Qinan Wang and Alexey Bobrick and Lindsay DeMarchi and Hila Glanz and Mor Rozner and Jacob E. Jencson and Armin Rest and Brian D. Metzger and Raffaella Margutti and Sebastian Gomez and Nathan Smith and Silvia Toonen and Joe S. Bright and Colin Norman and Ryan J. Foley and Alexander Gagliano and Julian H. Krolik and Stephen J. Smartt and Ashley V. Villar and Gautham Narayan and Ori Fox and Katie Auchettl and Daniel Brethauer and Alejandro Clocchiatti and Sophie V. Coelln and Deanne L. Coppejans and Georgios Dimitriadis and Andris Dorozsmai and Maria Drout and Wynn Jacobson-Galan and Bore Gao and Ryan Ridden-Harper and Charles Donald Kilpatrick and Tanmoy Laskar and David Matthews and Sofia Rest and Ken W. Smith and Candice McKenzie Stauffer and Michael C. Stroh and Louis-Gregory Strolger and Giacomo Terreran and Justin D. R. Pierel and Anthony L. Piro}, doi = {10.3847/1538-4357/adf6b1}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {9}, shortjournal = {The Astrophys. J.}, title = {SN 2019tsf: Evidence for extended hydrogen-poor CSM in the three-peaked light curve of stripped envelope of a type ib supernova}, volume = {992}, year = {2025}, }
• (2025). A tale of two sightlines: Comparison of hydrocarbon dust absorption bands toward cygnus OB2-12 and the galactic center. ApJ, 992(1), 8. (www)

  @article{ , abstract = {Infrared spectra of hydrocarbon dust absorption bands toward the bright hypergiant Cygnus OB2-12 are compared to published spectra of the Quintuplet Cluster, a sightline to the Galactic center. The Cyg OB2-12 data include a new ground-based 2.86−3.70 μ m spectrum and a previously published, but here further analyzed, spectrum of the 5.50–7.34 μ m region. Higher-spectral-resolution data for the Cyg OB2-12 sightline in the 3 μ m region allows a detailed comparison of the 3.4 μ m aliphatic bands to those observed toward the Quintuplet. Despite differences in interstellar environments along each sightline, strong similarities are observed in the central wavelengths and relative strengths for bands at ∼3.3, 3.4, 5.85, 6.2, and 6.85 μ m. Analysis of these bands, produced by aromatic, aliphatic, olefinic, hydrogenated, and oxygenated components, shows that carbonaceous dust is a significant component of the diffuse interstellar medium (ISM), second in abundance only to silicates, and is primarily aromatic in nature. The grains producing these bands likely consist of large aromatic carbon cores with thin aliphatic mantles composed of hydrogenated amorphous carbon. Laboratory analog spectra reproduce the observed aliphatic absorption bands well, supporting the presence of such mantles. We present evidence that the carriers of both the 3.4 μ m aliphatic and the 3.3 μ m aromatic bands reside exclusively in the diffuse ISM, and that the 3.3 μ m bands observed in the diffuse ISM differ from the 3.25 μ m band seen in dense clouds, implying chemically distinct carriers.}, archive = {J_ApJ}, author = {Yvonne J. Pendleton and T. R. Geballe and Laurie E. U. Chu and Marjorie Decleir and Karl D. Gordon and A. G. G. M. Tielens and Louis J. Allamandola and Jeroen Bouwman and J. E. Chiar and Curtis Dewitt and Burcu Gunay and Thomas Henning and Vito Mennella and M. E. Palumbo and Alexey Potapov and Maisie Rashman and Sascha Zeegers}, doi = {10.3847/1538-4357/adfc3d}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {8}, shortjournal = {The Astrophys. J.}, title = {A tale of two sightlines: Comparison of hydrocarbon dust absorption bands toward cygnus OB2-12 and the galactic center}, volume = {992}, year = {2025}, }
• (2025). Active galactic nucleus star dynamics under the influence of Outflow–Ambient interactions. ApJ, 992(1), 7. (www)

  @article{ , abstract = {Stars with outflows interacting with ambient gas experience accelerations arising from the gravitational feedback induced by the interaction structure. In this work, three-dimensional local shearing box simulations are performed to investigate the dynamical evolution of a star with outflows embedded in the outer regions of an active galactic nucleus (AGN) disk. Two types of stellar wind are considered, isotropic winds and axisymmetric jets, along with variations in the radial pressure gradient profile. The results show that antifriction enables AGN stars to acquire angular momentum from the ambient gas, resulting in outward migration away from the disk center. The formation and stability of the headwind structure, which is crucial for maintaining antifriction, are sensitive to both the strength of the stellar outflow and the radial pressure gradient of the disk gas. Once the headwind structure is disrupted, the antifriction effect ceases to operate effectively. A case study is also presented, focusing on a stellar-mass black hole (sBH) in an AGN disk. It is shown that jet material launched along the z -axis is confined to the trailing side of the object’s motion by high gas inflow velocities, thereby activating antifriction and inducing outward migration. If such an sBH migrates inward initially, the interplay between inward and outward migration may trap it at an equilibrium radius, potentially facilitating the formation and merger of black hole binaries.}, archive = {J_ApJ}, author = {Muxin Liu and Lile Wang and Peng Peng}, doi = {10.3847/1538-4357/adfc66}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {7}, shortjournal = {The Astrophys. J.}, title = {Active galactic nucleus star dynamics under the influence of Outflow–Ambient interactions}, volume = {992}, year = {2025}, }
• (2025). A novel approach to identifying substructures through analysis of metallicity distribution functions. ApJ, 992(1), 6. (www)

  @article{ , abstract = {We present a new method for identifying Galactic halo substructures accreted from dwarf galaxies by combining metallicity distribution functions (MDFs) with orbital parameters. Using apogalactic distance–orbital phase space, we assume that the MDF peak of a substructure reflects its progenitor’s chemical signature. We test this approach with two Galactic potentials (St \ddot{a} ckel and McMillan) and find consistent results. Our sample consists of retrograde halo stars with low orbital inclinations and intermediate eccentricities (0.5 < e ≤ 0.7), drawn from Sloan Digital Sky Survey and Large sky Area Multi-Object Fiber Spectroscopic Telescope spectroscopy combined with Gaia DR3 astrometry. We identify four distinct low-inclination retrograde substructures (LRS 1, LRS 2, LRS 3, LRS 4) with MDF peaks at [Fe/H] = −1.5, −1.7, −1.9, and −2.1, respectively; LRS 3 is newly discovered. Further analysis reveals an additional stream (LRS 2B) with [Fe/H] = −2.3 embedded within LRS 2; the remaining LRS 2 stars (LRS 2A) are associated with Sequoia. LRS 1 is likely linked to Thamnos 2 and Arjuna, and LRS 4 is likely linked to I’itoi. Comparison with the ED-2 stream suggests that LRS 2B is chemically distinct, but high-resolution spectroscopy is required to confirm whether they originate from separate progenitors. Our MDF-based approach demonstrates the utility of chemodynamical space for uncovering halo substructures, while highlighting caveats such as metallicity gradients and redshift evolution of the mass–metallicity relation, which may blur the mapping between MDF peaks and progenitors.}, archive = {J_ApJ}, author = {Young Kwang Kim and Young Sun Lee and Timothy C. Beers}, doi = {10.3847/1538-4357/adfd58}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {6}, shortjournal = {The Astrophys. J.}, title = {A novel approach to identifying substructures through analysis of metallicity distribution functions}, volume = {992}, year = {2025}, }
• (2025). PSR j1838−0655: X-ray observations with NICER and NuSTAR. ApJ, 992(1), 5. (www)

  @article{ , abstract = {We report on the timing and spectral properties of PSR J1838-0655 using joint observations from the Neutron Star Interior Composition Explorer (NICER) and the Nuclear Spectroscopic Telescope Array (NuSTAR). By disentangling the pulsar’s emission from its surrounding wind nebula across joint Chandra, NuSTAR, and NICER observations, we find the pulsar’s broadband X-ray spectrum (1.3–79 keV) is best-described by a broken power-law model. The model features photon indices of Γ 1 = 1.19 ± 0.07 and Γ 2 = 1.47 ± 0.02 below and above a break energy of E b = 7.7 ± 0.8 keV. The resulting unabsorbed 2–10 keV flux from the pulsar is (9.{5}_{-0.3}^{+0.4})\times 1{0}^{-12}\,{\rm{erg}}\,{{\rm{cm}}}^{-2}\,{{\rm{s}}}^{-1} . Furthermore, timing analysis of NICER data spanning MJD 58250 to 60630 reveals a very large glitch occurring around MJD 59300, characterized by a frequency jump of Δ ν = 29.367(7) × 10 −6 Hz, which can be well explained by the vortex creep model. Phase-resolved spectral analysis indicates a clear anticorrelation between the photon index and the pulse intensity, suggesting spectral hardening at the pulse peak.}, archive = {J_ApJ}, author = {Xian-Ao Wang and Han-Long Peng and Jin-Tao Zheng and Shi-Qi Zhou and Wen-Tao Ye and Ming-Yu Ge and Xiang-Hua Li and Shi-Jie Zheng}, doi = {10.3847/1538-4357/adff77}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {5}, shortjournal = {The Astrophys. J.}, title = {PSR j1838−0655: X-ray observations with NICER and NuSTAR}, volume = {992}, year = {2025}, }
• (2025). Spatiotemporal low first ionization potential abundance: A catalyst for coronal condensation. ApJ, 992(1), 4. (www)

  @article{ , abstract = {Radiative losses play a critical role in the cooling of plasmas. When chromospheric plasma is sufficiently heated, it can flow into coronal loops, which subsequently cool down due to radiation. From observations, we infer that this cooling does not occur uniformly, often resulting in coronal condensations such as coronal rain. To date, coronal condensations have only been found in simulations of steadily heated loops, and never in impulsively heated ones. We implement spatiotemporally variable elemental abundances in a radiative hydrodynamic code. Flows, including chromospheric evaporation, directly cause a shift in the local elemental abundances, which then affects the local radiative loss rate. As a consequence, we find that incorporating spatiotemporal low first ionization potential elemental abundances into coronal loop simulations directly causes coronal condensations, which are otherwise absent in impulsively heated loop or flare models. We conclude that spatiotemporal variations in elemental abundances are a fundamental feature of the solar corona and are therefore necessary to accurately model radiation.}, archive = {J_ApJ}, author = {Luke Fushimi Benavitz and Jeffrey W. Reep and Lucas A. Tarr and Andy S.H. To}, doi = {10.3847/1538-4357/ae019d}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {4}, shortjournal = {The Astrophys. J.}, title = {Spatiotemporal low first ionization potential abundance: A catalyst for coronal condensation}, volume = {992}, year = {2025}, }
• (2025). The potential of the SPHEREx mission for characterizing polycyclic aromatic hydrocarbon 3.3 μm emission in nearby galaxies. ApJ, 992(1), 3. (www)

  @article{ , abstract = {Together with gas, stars, and supermassive black holes, dust is crucial in stellar and galaxy evolution. Hence, understanding galaxies’ dust properties across cosmic time is critical to studying their evolution. In addition to photometric constraints on the absorption of blue light and its reemission at infrared wavelengths, dust grain properties can be explored spectroscopically via polycyclic aromatic hydrocarbon (PAH) emission bands in the mid-IR. The new SPHEREx space telescope conducts an all-sky spectrophotometric survey of stars and galaxies at wavelengths of 0.75–5 μ m, making it ideal for studying the widespread presence of the 3.3 μ m PAH emission across galaxy populations out to z ∼ 0.4. In this paper, we simulated galaxy spectra to investigate SPHEREx's capability to study PAH emission in such galaxies. We find that for the all-sky survey the PAH 3.3 μ m emission band flux can be measured to 30% accuracy at {\mathrm{log}}\,(M/{M}_{\odot })\gt 9.5 and star formation rate (SFR) > 1 M ⊙ yr −1 at z = 0.1, {\mathrm{log}}\,(M/{M}_{\odot })\gt 10.5 and SFR > 10 M ⊙ yr −1 at z = 0.2–0.3, and {\mathrm{log}}\,(M/{M}_{\odot })\gt 11 and SFR > 100 M ⊙ yr −1 at z = 0.4. For deep SPHEREx fields, a factor of ∼10 deeper sensitivity limits can be reached. Overall, SPHEREx will enable the measurement of the 3.3 μ m PAH band emission in several hundred thousand galaxies across the sky, providing a population study of the smallest dust grains (“nano grains”) and radiation properties in massive galaxies in the nearby Universe.}, archive = {J_ApJ}, author = {Edward Zhang and Andreas L. Faisst and Brendan P. Crill and Hanae Inami and Thomas Lai and Youichi Ohyama and Jeonghyun Pyo and Rachel Akeson and Matthew L. N. Ashby and James J. Bock and Yun-Ting Cheng and Yi-Kuan Chiang and Asantha Cooray and Olivier Doré and Richard M. Feder and Yongjung Kim and Bomee Lee and Daniel Masters and Gary Melnick and Roberta Paladini and Michael W. Werner}, doi = {10.3847/1538-4357/adfd5a}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {3}, shortjournal = {The Astrophys. J.}, title = {The potential of the SPHEREx mission for characterizing polycyclic aromatic hydrocarbon 3.3 μm emission in nearby galaxies}, volume = {992}, year = {2025}, }
• (2025). The first day of a type ia supernova from a double-degenerate binary. ApJ, 992(1), 2. (www)

  @article{ , abstract = {Supernovae in binary star systems involve a hydrodynamical interaction between the ejecta and a binary companion. This collision results in shock heating and a modified density structure for the ejecta, both of which affect the light curve. As highlighted by D. Kasen, these considerations are particularly relevant for Type Ia supernovae, as the companion is expected to be Roche-lobe filling at the time of the explosion. We simulate here the interaction between Type Ia supernova ejecta and a white dwarf donor using Athena++, finding the formation of a low-density wake extending to higher velocities than the unperturbed ejecta. Radiation hydrodynamics is then used to generate synthetic light curves for the first day after the explosion for a range of viewing angles. We find that the hot, high-velocity, shocked ejecta yield L > 10 40 erg s −1 over half the sky in the first few hours. The photosphere within the shock-heated ejecta cools and recedes in velocity space, partially obscuring it from view, as heating from radioactive nickel becomes increasingly important in driving the supernova’s luminosity. By one day after the explosion, the luminosity measured by observers looking directly into the wake is dimmer than that of a normal Type Ia supernova by 15% due to the modified density structure.}, archive = {J_ApJ}, author = {Gabriel Kumar and Logan J. Prust and Lars Bildsten}, doi = {10.3847/1538-4357/adfdd7}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {2}, shortjournal = {The Astrophys. J.}, title = {The first day of a type ia supernova from a double-degenerate binary}, volume = {992}, year = {2025}, }
• (2025). Detection of diffuse radio emission inside the supernova remnant g338.3-0.0 associated with the γ-ray source HESS j1640-465. ApJ, 992(1), 1. (www)

  @article{ , abstract = {We report the discovery of diffuse radio emission within SNR G338.3−0.0 using new MeerKAT observations at 816 MHz and 1.4 GHz. The radio emission spatially overlaps with the X-ray pulsar wind nebula (PWN) powered by PSR J1640−4631 and the GeV/TeV γ -ray source HESS J1640−465. The morphology of this radio emission is centrally peaked and its extent is well contained within the SNR shell. A lack of mid- and far-infrared counterparts and the absence of cataloged H ii regions argue against a thermal origin, while the morphology and radial profile are suggestive of a PWN origin powered by PSR J1640−4631. Under this assumption, we use a one-zone, time-dependant model to reproduce the size and broadband (radio, X-ray, and γ -ray) spectral energy distribution of the PWN. The modeling and broadband properties of this PWN suggest it is currently interacting with the reverse shock within its host SNR. This evolutionary stage is associated with particles escaping the PWN and entering the interstellar medium, suggesting this object may be an important source of Galactic PeV e ± .}, archive = {J_ApJ}, author = {Moaz Abdelmaguid and Joseph D. Gelfand and J. A. J. Alford}, doi = {10.3847/1538-4357/adfec1}, journal = {The Astrophysical Journal}, month = {10}, number = {1}, pages = {1}, shortjournal = {The Astrophys. J.}, title = {Detection of diffuse radio emission inside the supernova remnant g338.3-0.0 associated with the γ-ray source HESS j1640-465}, volume = {992}, year = {2025}, }
• (2025). Erratum: “MINDS. JWST-MIRI observations of a spatially resolved atomic jet and polychromatic molecular wind toward SY cha” (2025, ApJ, 980, 148). ApJ, 991(2), 232. (www)

  @article{ , archive = {J_ApJ}, author = {Kamber R. Schwarz and Matthias Samland and Göran Olofsson and Thomas Henning and Andrew Sellek and Manuel Güdel and Benoît Tabone and Inga Kamp and Pierre-Olivier Lagage and Ewine F. van Dishoeck and Alessio Caratti o Garatti and Adrian M. Glauser and Tom P. Ray and Aditya M. Arabhavi and Valentin Christiaens and R. Franceschi and Danny Gasman and Sierra L. Grant and Jayatee Kanwar and Till Kaeufer and Nicolas T. Kurtovic and Giulia Perotti and Milou Temmink and Marissa Vlasblom}, doi = {10.3847/1538-4357/ae0603}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {232}, shortjournal = {The Astrophys. J.}, title = {Erratum: “MINDS. JWST-MIRI observations of a spatially resolved atomic jet and polychromatic molecular wind toward SY cha” (2025, ApJ, 980, 148)}, volume = {991}, year = {2025}, }
• (2025). Follow-up investigation of 11 pulsars discovered in the commensal radio astronomy FAST survey. ApJ, 991(2), 231. (www)

  @article{ , abstract = {In this paper, we study 11 pulsars that were discovered by the Five-hundred-meter Aperture Spherical radio Telescope (FAST) in the Commensal Radio Astronomy FAST Survey. We report their phase-connected timing ephemeris, polarization pulse profiles, and Faraday rotation measures. The timing analysis shows that our sample includes seven normal pulsars and four (PSRs J0245+3219, J1437+3049, J1759−1248, and J1813−0852) millisecond pulsars, with periods ranging from 3.15 ms to 2.54 s, characteristic ages from 5.48 × 10 5 to 1.06 × 10 10 yr, and surface magnetic fields from 1.46 × 10 8 to 1.18 × 10 13 G. Six normal pulsars exhibit rich radiation characteristics, including nulling and subpulse drifting. PSR J0245+3219 (30.93 ms) has a spin period, characteristic age, surface magnetic field, and galactic height that are consistent with the parameters of disrupted recycled pulsars. PSR J1813−0852 (4.23 ms) is in a binary system with an orbit of 83.47 days, an eccentricity of 2.9 × 10 −4 , and its companion has a mass ranging from 0.28 to 0.76 M ⊙ . PSR J1813−0852 exhibits a spin period, companion mass, and orbital eccentricity that align well with the predicted characteristics of a millisecond pulsar–helium white dwarf systems.}, archive = {J_ApJ}, author = {K. Yang and L. Li and J. P. Yuan and N. Wang and D. Li and P. Wang and C. C. Miao and W. W. Zhu and M. Y. Xue and W. M. Yan and J. B. Wang and R. Yuen and G. L. Lü and C. H. Zhu and J. M. Yao and Q. D. Wu and S. Q. Wang and S. N. Sun and F. F. Kou and D. Zhao and Z. Wang and J. Xu and C. Sun and Y. Feng and Z. J. Liu and X. L. Miao and L. Q. Meng and C. H. Niu and J. R. Niu and L. Qian and X. Y. Xie and Y. F. Xiao and Y. L. Yue and S. P. You and S. J. Dang and X. H. Yu and R. S. Zhao and X. Zhou and L. Zhang and J. F. Wu and C. J. Wang and Y. B. Wang and Z. Y. Gan}, doi = {10.3847/1538-4357/adfc71}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {231}, shortjournal = {The Astrophys. J.}, title = {Follow-up investigation of 11 pulsars discovered in the commensal radio astronomy FAST survey}, volume = {991}, year = {2025}, }
• (2025). Gamma-ray burst pulse structures and emission mechanisms. ApJ, 991(2), 230. (www)

  @article{ , abstract = {The prompt phase X-ray and gamma-ray light curves of gamma-ray bursts (GRBs) exhibit erratic and complex behaviors, often with multiple pulses. The temporal shape of the individual pulses is often modeled as “fast rise exponential decay” (FRED). Here, we introduce a novel fitting function to quantify the pulse asymmetry. We conduct a light-curve and a time-resolved spectral analysis on 61 pulses from 22 GRBs detected by the Fermi Gamma-ray Burst Monitor. Contrary to previous claims, we find that only ∼50% of the pulse light curves in our sample show a FRED shape, while about 25% have a symmetric light curve, with the other 25% having a mixed shape. Furthermore, our analysis reveals a clear trend: in multipulse bursts, the initial pulse tends to exhibit the most symmetric light curve, while subsequent pulses become increasingly asymmetric, adopting a more FRED-like shape. Additionally, we correlate the temporal and spectral shapes of the pulses. By fitting the spectra with the classical “Band” function, we find a moderate positive Spearman's correlation index of 0.23 between the pulse asymmetry and the low-energy spectral index {\alpha }_{\max } (the maximum value across all time bins covering an individual pulse). Thus, during GRB light curves, the pulses tend to get more asymmetric and spectrally softer with time. We interpret this as a transition in the dominant emission mechanism, from photospheric (symmetric-like and hard) to nonthermal emission above the photosphere, and show that this interpretation aligns with a GRB jet Lorentz factor of the order of a few tens in many cases.}, archive = {J_ApJ}, author = {A Gowri and A. Pe’er and F. Ryde and H. Dereli-Bégué}, doi = {10.3847/1538-4357/adec81}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {230}, shortjournal = {The Astrophys. J.}, title = {Gamma-ray burst pulse structures and emission mechanisms}, volume = {991}, year = {2025}, }
• (2025). The 2021 hot-type symbiotic outburst of YY herculis: An optical follow-up study. ApJ, 991(2), 229. (www)

  @article{ , abstract = {We have followed up on the hot-type classical symbiotic outburst reported in YY Her using the Himalayan Chandra Telescope. The outburst coincides with the secondary minima of the system. Approximately 12 similar brightening events have been reported between 1890 and 2020, with only the 1993 outburst being studied spectroscopically. In our study, we monitored the system from 2021 to 2023, covering ∼1.5 orbital cycles, providing an opportunity to understand the spectral evolution of the outburst over a complete orbital period of YY Her. We found that the temperature and luminosity estimations based on emission line fluxes exhibit orbital phase dependence. The values estimated at phase 0.5, corresponding to the secondary minimum, were the most reliable. The temperature of the hot component is ≈1.41 × 10 5 K, and the luminosity is ≈1020 L ⊙ during the outburst, reduced to ≈1.3 × 10 5 K and ≈830 L ⊙ after one orbital cycle at phase 0.5. Temperature estimations during the outbursts suggest that YY Her exhibits both hot-type (2021) and cool-type (1993) behavior, similar to another symbiotic star, AG Dra. Using variations of the Ca II absorption lines, we confirmed the contribution of the ellipsoidal effect in secondary minima in the YY Her light curve.}, archive = {J_ApJ}, author = {L. S. Sonith and U. S. Kamath}, doi = {10.3847/1538-4357/adf1e7}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {229}, shortjournal = {The Astrophys. J.}, title = {The 2021 hot-type symbiotic outburst of YY herculis: An optical follow-up study}, volume = {991}, year = {2025}, }
• (2025). The diversity of metal enrichment and abundance patterns at high redshift: A magellan survey of gas-rich galaxies traced by damped lyα absorbers at z ∼ 5. ApJ, 991(2), 228. (www)

  @article{ , abstract = {A powerful technique to trace the signatures of the first stars is through the metal enrichment in concentrated reservoirs of hydrogen, such as the damped Ly α absorbers (DLAs) in the early Universe. We conducted a survey aimed at discovering DLAs along sight lines to high- z quasars in order to measure element abundances at z > 4. Here we report our first results from this survey for 10 DLAs with redshifts of ≈4.2–5.0. We determine abundances of C, O, Si, S, and Fe, and thereby the metallicities and dust depletions. We find that DLA metallicities at z > 4.5 show a wide diversity spanning ∼3 orders of magnitude. The metallicities of DLAs at 3.7 < z < 5.3 show a larger dispersion compared to that at lower redshifts. Combining our sample with the literature, we find a relatively smooth evolution of metallicity with redshift out to z ∼ 5.3, with a tentative (∼2 σ ) indication of a slight rise in metallicity at 4.5 < z < 5.3. The relative abundances exhibit C enhancement for both metal-poor and metal-enriched DLAs. In addition, α -element enhancement is evident in some DLAs, including a DLA at z = 4.7 with a supersolar metallicity. Comparing [C/O] and [Si/O] with model predictions, four DLAs in our survey seem consistent with a nonzero Population III contribution (three with ≳30% Population III contribution). Combining our sample and the literature, we find the dust depletion strength and dust-to-metal ratios to correlate positively with the total (gas+solid phase) metallicity, confirming the presence of metal-rich, dusty DLAs even at ∼1 billion years after the Big Bang.}, archive = {J_ApJ}, author = {Jianghao Huyan and Varsha P. Kulkarni and Suraj Poudel and Nicolas Tejos and Celine Péroux and Sebastian Lopez}, doi = {10.3847/1538-4357/adf63e}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {228}, shortjournal = {The Astrophys. J.}, title = {The diversity of metal enrichment and abundance patterns at high redshift: A magellan survey of gas-rich galaxies traced by damped lyα absorbers at z ∼ 5}, volume = {991}, year = {2025}, }
• (2025). JWST Q3D program: Active galactic nucleus photoionization and shock ionization in a red quasar at z = 0.4. ApJ, 991(2), 227. (www)

  @article{ , abstract = {Red quasars, often associated with potent [O iii ] outflows on both galactic and circumgalactic scales, may play a pivotal role in galactic evolution and black hole feedback. In this work, we explore the [Fe ii ] emission in one such quasar at z = 0.4352–F2M J110648.32+480712.3 using the integral field unit mode of the Near Infrared Spectrograph aboard the JWST. Our observations reveal clumpy [Fe ii ] gas located to the south of the quasar. By comparing the kinematics of [Fe ii ] and [O iii ], we find that the clumpy [Fe ii ] gas in the southeast and southwest aligns with the outflow, exhibiting similar median velocities up to v 50 = 1200 km s −1 and high velocity widths W 80 > 1000 km s −1 . In contrast, the [Fe ii ] gas to the south shows kinematics inconsistent with the outflow, with W 80 ∼ 500 km s −1 , significantly smaller than the [O iii ] at the same location, suggesting that the [Fe ii ] may be confined within the host galaxy. Utilizing standard emission-line diagnostic ratios, we map the ionization sources of the gas. According to the MAPPINGS III shock models for [Fe ii ]/Pa β , the regions to the southwest and southeast of the quasar are primarily photoionized. Conversely, the [Fe ii ] emission to the south is likely excited by shocks generated by the back-pressure of the outflow on the galaxy disk, a direct signature of the impact of the quasar on its host.}, archive = {J_ApJ}, author = {Swetha Sankar and Nadia L. Zakamska and David S. N. Rupke and Weizhe Liu and Dominika Wylezalek and Sylvain Veilleux and Caroline Bertemes and Nadiia Diachenko and Yu-Ching Chen and Yuzo Ishikawa and Andrey Vayner and Nicole P. H. Nesvadba and Guilin Liu and Andy D. Goulding and Dieter Lutz}, doi = {10.3847/1538-4357/adf967}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {227}, shortjournal = {The Astrophys. J.}, title = {JWST Q3D program: Active galactic nucleus photoionization and shock ionization in a red quasar at z = 0.4}, volume = {991}, year = {2025}, }
• (2025). White dwarfs in wide binaries: The strong effects of stellar evolution and mass loss. ApJ, 991(2), 226. (www)

  @article{ , abstract = {We examine the statistics of main-sequence/main-sequence, main-sequence/white-dwarf, and white-dwarf/white-dwarf wide binaries at 10 2.5 –10 4 au separations in Gaia data. For binaries containing a white dwarf, we find a complex dependence of the wide-binary fraction on the white-dwarf mass, including a steep decline as a function of mass at >0.6 M ⊙ . Furthermore, we find that wide binaries containing white dwarfs have significantly lower eccentricities than main-sequence binaries at the same separations. To model these observations, we compute the effects of post-main-sequence mass loss on the orbital parameters of wide binaries in all regimes of timescales, from secular to impulsive, and incorporate these dynamics in a population synthesis model. We find that adiabatic expansion of the orbits in binaries with slow enough evolutionary processes is the most likely explanation for the puzzling eccentricity distribution of white-dwarf wide binaries. The steeply declining white-dwarf binary fraction as a function of mass requires that the timescale for mass loss must be significantly shorter for high-mass stars (10 3 –10 4 yr) than for the low-mass ones. We confirm previous studies that suggested that recoil in the range 0.25–4 km s −1 is required to explain the observed distribution of separations of white-dwarf wide binaries. Finally, for low-mass white dwarfs (<0.5 M ⊙ ), we see interesting signatures of their formation due to close binary evolution in their wide-binary statistics. Our observations and modeling provide a novel dynamical constraint on the mass-loss stages of stellar evolution that are difficult to probe with direct observations.}, archive = {J_ApJ}, author = {Hsiang-Chih Hwang and Nadia L. Zakamska}, doi = {10.3847/1538-4357/adfa1c}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {226}, shortjournal = {The Astrophys. J.}, title = {White dwarfs in wide binaries: The strong effects of stellar evolution and mass loss}, volume = {991}, year = {2025}, }
• (2025). γ-ray pulsar emission is mostly stable on timescales from minutes to years. ApJ, 991(2), 225. (www)

  @article{ , abstract = {We present a method for the detection and characterization of random changes in the flux from γ -ray pulsars on sub-hour timescales, much shorter than variations that can be accessed using direct flux measurements. Flux variations are a proxy for the variations in spindown power ( \dot{E} ) or particle acceleration, which can be produced by random switches between quasi-stable configurations of the pulsar magnetosphere. This technique therefore probes the stability of pulsar magnetospheres and discrete spindown states on timescales much shorter than can be achieved with pulsar timing. We apply the method to a sample of 115 bright γ -ray pulsars, finding no new instances of state changes. We derive the sensitivity of the method and find that, for a wide range of possible state-changing models, over a wide range of timescales, we can limit the amplitude of flux ( \dot{E} ) variations to <10%. Substantial nulling is excluded in nearly all cases. The best cases limit variations of any sort to ≤1%. These results indicate that γ -ray pulsar magnetospheres maintain a single configuration or narrow range of configurations with nearly constant power output.}, archive = {J_ApJ}, author = {M. Kerr}, doi = {10.3847/1538-4357/adfa95}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {225}, shortjournal = {The Astrophys. J.}, title = {γ-ray pulsar emission is mostly stable on timescales from minutes to years}, volume = {991}, year = {2025}, }
• (2025). XRISM reveals complex ionization and velocity structures in the GX 340+0 X-ray binary. ApJ, 991(2), 224. (www)

  @article{ , abstract = {We present the first high-resolution XRISM spectrum of the neutron star low-mass X-ray binary GX 340+0, revealing unprecedented detail in its emission and absorption features. The spectrum reveals a rich and complex Fe xxv He α line profile and a P Cygni profile from Ca xx . We use the state-of-the-art spectral synthesis code Cloudy to model the emission and absorption features in detail. Our analysis reveals multi-ionization and multivelocity structures, where the combination of broad (∼800 km s −1 ) and narrow (∼360 km s −1 ) line components, along with rest-frame and blueshifted emission and absorption lines, accounts for the observed line profile complexity. We identify a modest ∼2735 km s −1 accretion disk wind exhibiting both absorption and emission features. We also detect a relativistic reflection feature in the spectrum, which we model using relxillNS , specifically designed to characterize X-ray reprocessing in accretion disks around neutron stars. Furthermore, we examine the detailed physics of the Fe xxv He α complex, focusing on the forbidden-to-resonance line ratio under the influence of continuum pumping and optical depth effects.}, archive = {J_ApJ}, author = {Priyanka Chakraborty and Randall Smith and Lia Corrales and Elisa Costantini and María Díaz Trigo and Adam Foster and Caroline Kilbourne and Renee Ludlam and Takao Nakagawa and Frederick S. Porter and Ioanna Psaradaki and Hiromitsu Takahashi and Tahir Yaqoob and Sascha Zeegers}, doi = {10.3847/1538-4357/adfb65}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {224}, shortjournal = {The Astrophys. J.}, title = {XRISM reveals complex ionization and velocity structures in the GX 340+0 X-ray binary}, volume = {991}, year = {2025}, }
• (2025). Constrain the hubble constant from extreme mass ratio inspirals dark sirens using galaxy clusters. ApJ, 991(2), 223. (www)

  @article{ , abstract = {Extreme mass ratio inspirals (EMRIs) are key observational targets for future space-based gravitational wave detectors and hold significant value in cosmological research. As a type of “standard siren,” EMRIs offer an independent method to measure the Hubble constant, providing new hope for resolving the “Hubble tension” problem. However, when using the dark siren method combined with galaxy catalogs to statistically infer redshifts, EMRI events occurring in low-luminosity galaxies may not be fully recorded in the galaxy catalogs, leading to potential true hosts being missed. To address this, we propose using galaxy cluster catalogs, which contain numerous member galaxies, including faint ones, effectively reducing the risk of missing true hosts. In this study, we randomly injected three EMRI events and simulated a 2 yr observation of these events using both Laser Interferometric Space Antenna (LISA) and the joint LISA–Taiji network to demonstrate the improvements brought about by incorporating galaxy cluster catalogs into the dark siren methodology. For these three cases, compared to using galaxy catalogs alone, incorporating galaxy cluster catalogs enhanced the measurement precision of the Hubble constant to varying degrees, with a maximum improvement of approximately 41.00%. These results indicate that employing galaxy cluster catalogs in EMRI-based dark siren analyses can more effectively constrain the Hubble constant H 0 .}, archive = {J_ApJ}, author = {Jian-Dong Liu and Wen-Biao Han and Qianyun Yun}, doi = {10.3847/1538-4357/adfc3e}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {223}, shortjournal = {The Astrophys. J.}, title = {Constrain the hubble constant from extreme mass ratio inspirals dark sirens using galaxy clusters}, volume = {991}, year = {2025}, }
• (2025). Morphological demographics of galaxies at z ∼ 10–16: Log-normal size distribution and exponential profiles consistent with the disk formation scenario. ApJ, 991(2), 222. (www)

  @article{ , abstract = {We homogeneously investigate the morphological properties of 169 galaxies at z ∼ 10–16 with deep JWST NIRCam images employing our established techniques of GALFIT modeling and uncertainty evaluation (systematics+statistics). We obtain effective radii r e ranging 20–500 pc, with a distribution significantly broader than the scatter made by the uncertainties. We find that the r e distribution is well described by a log-normal distribution with a mean of {r}_{{{\rm{e}}}}=13{3}_{-12}^{+13} pc and a standard deviation of {\sigma }_{{\mathrm{ln}}\,{r}_{{{\rm{e}}}}}=0.52\pm 0.08 . The standard deviation is comparable to that of local galaxies, indicating no significant evolution over z ∼ 0–10. We also find that the axis ratio distribution is nearly uniform, statistically similar to that of local spirals. We estimate the virial radius r vir from the stellar masses via the star formation main sequence and stellar-to-halo mass relation, obtaining a stellar-to-halo size ratio {r}_{{{\rm{e}}}}/{r}_{{\mathrm{vir}}}=0.01{5}_{-0.005}^{+0.015} , which is comparable to those of star-forming galaxies in the local and low- z Universe. Our results of (1) the log-normal r e distribution, (2) the uniform axis ratio distribution, and (3) a mean radial profile consistent with an exponential profile ( n = 1.3 ± 0.6) suggest that galaxies at z ∼ 10–16 generally follow the classical galaxy disk formation scenario with a specific disk angular momentum fraction of j d / m d ∼ 0.5–1. Interestingly, we identify two remarkable outliers GN-z11 ( z spec = 10.60) and GHZ2 ( z spec = 12.34) with {r}_{{{\rm{e}}}}=5{5}_{-6}^{+5} pc and 39 ± 11 pc, respectively, that may not be explained by disk structures but by active galactic nucleus or compact star-forming galaxies merging underway in short periods of time, as reproduced in numerical simulations.}, archive = {J_ApJ}, author = {Yoshiaki Ono and Masami Ouchi and Yuichi Harikane and Hidenobu Yajima and Kimihiko Nakajima and Seiji Fujimoto and Minami Nakane and Yi Xu}, doi = {10.3847/1538-4357/adfc4d}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {222}, shortjournal = {The Astrophys. J.}, title = {Morphological demographics of galaxies at z ∼ 10–16: Log-normal size distribution and exponential profiles consistent with the disk formation scenario}, volume = {991}, year = {2025}, }
• (2025). Impacts of the metagalactic ultraviolet background on circumgalactic medium absorption systems. ApJ, 991(2), 221. (www)

  @article{ , abstract = {Among the many different pieces of physics that go into simulations of the circumgalactic medium (CGM), the metagalactic ultraviolet background (UVB) plays a significant role in determining the ionization state of different metal species. However, the UVB is uncertain, with multiple models having been developed by various research groups over the past several decades. In this work, we examine how different UVB models influence the ionic column densities of CGM absorbers. We use these UVB models to infer ion number densities in the Figuring Out Gas and Galaxies In Enzo (FOGGIE) galaxy simulations at z = 2.5 and use the Synthetic Absorption Line Surveyor Application package to identify absorbers. Absorbers are then matched across UVB models based on their line-of-sight position so that their column densities can be compared. From our analysis, we find that changing the UVB model produces significant changes in ionization, specifically at lower gas densities and higher temperatures where photoionization dominates over collisional ionization. We also find that the scatter of column density differences between models tends to increase with increasing ionization energy, with the exception of H i , which has the highest scatter of all species we examined.}, archive = {J_ApJ}, author = {Elias Taira and Claire Kopenhafer and Brian W. O’Shea and Alexis Manning and Evelyn Fuhrman and Molly S. Peeples and Jason Tumlinson and Britton D. Smith}, doi = {10.3847/1538-4357/adfc4e}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {221}, shortjournal = {The Astrophys. J.}, title = {Impacts of the metagalactic ultraviolet background on circumgalactic medium absorption systems}, volume = {991}, year = {2025}, }
• (2025). The blooming tree algorithm at work: Clusters, filaments, and superclusters in the field of a2029. ApJ, 991(2), 220. (www)

  @article{ , abstract = {The Blooming Tree (BT) algorithm, based on the hierarchical clustering method, is designed to identify clusters, groups, and substructures from galaxy redshift surveys. We apply the BT algorithm to a wide-field (10 × 10 deg 2 ) spectroscopic data set centered on the galaxy cluster A2029. The BT algorithm effectively identifies all the X-ray luminous clusters and most of the optical clusters known in the literature, numerous groups, and the filaments surrounding the clusters, associating a list of galaxy members to each structure. By lowering the detection threshold, the BT algorithm also identifies the three superclusters in the field. The BT algorithm arranges the clusters and groups that make up the superclusters in a hierarchical tree according to their pairwise binding energy: the algorithm thus unveils the possible accretion history of each supercluster and their future evolution. These results show how the BT algorithm can represent a crucial tool to investigate the formation and evolution of cosmic structures on nonlinear and mildly nonlinear scales.}, archive = {J_ApJ}, author = {Heng Yu and Antonaldo Diaferio}, doi = {10.3847/1538-4357/adfc5d}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {220}, shortjournal = {The Astrophys. J.}, title = {The blooming tree algorithm at work: Clusters, filaments, and superclusters in the field of a2029}, volume = {991}, year = {2025}, }
• (2025). An integral-based technique to accelerate the monte carlo radiative transfer computation for supernovae. ApJ, 991(2), 219. (www)

  @article{ , abstract = {We present an integral-based technique (IBT) algorithm to accelerate supernova (SN) radiative transfer calculations. The algorithm utilizes “integral packets,” which are calculated by the path integral of the Monte Carlo (MC) energy packets, to synthesize the observed spectropolarimetric signal at a given viewing direction in a 3D time-dependent radiative transfer program. Compared to the event-based technique (EBT) proposed by M. Bulla et al., our algorithm significantly reduces the computation time and increases the MC signal-to-noise ratio (S/N). Using a 1D spherical symmetric Type Ia SN ejecta model DDC10 and its derived 3D model, the IBT algorithm has successfully passed the verification of spherical symmetry and cross comparison on a 3D SN model with the direct-counting technique and EBT. Notably, with our algorithm implemented in the 3D MC radiative transfer code SEDONA, the computation time is faster than EBT by a factor of 10−30, and the S/N is better by a factor of 1.5−3, with the same number of MC quanta.}, archive = {J_ApJ}, author = {Xingzhuo Chen and Lifan Wang and Daniel Kasen}, doi = {10.3847/1538-4357/adfcd9}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {219}, shortjournal = {The Astrophys. J.}, title = {An integral-based technique to accelerate the monte carlo radiative transfer computation for supernovae}, volume = {991}, year = {2025}, }
• (2025). The SDSS-V black hole mapper reverberation mapping project: Multiline dynamical modeling of a highly variable active galactic nucleus with decade-long light curves. ApJ, 991(2), 218. (www)

  @article{ , abstract = {We present dynamical modeling of the broad-line region (BLR) of the highly variable active galactic nucleus (AGN) SDSS J141041.25+531849.0 ( z = 0.359) using photometric and spectroscopic monitoring data from the Sloan Digital Sky Survey (SDSS) Reverberation Mapping project and the current fifth-generation SDSS Black Hole Mapper program, spanning from early 2013 to early 2023. We model the geometry and kinematics of the BLR in the H β , H α , and Mg ii emission lines for three different time periods to measure the potential change of structure within the BLR across time and line species. We find a moderately face-on ({i}_{\mathrm{full}-\mathrm{state}}=29.{68}_{-3.62}^{+4.74}\,\deg ) thick-disk ({\theta }_{\mathrm{opn},\mathrm{full}-\mathrm{state}}=42.{04}_{-3.96}^{+4.32}\,\deg ) geometry for most BLRs, with a joint estimate for the mass of the supermassive black hole for each of three time periods, yielding {\mathrm{log}}_{10}({M}_{{\rm{BH}}}/{M}_{\odot })=8.1{0}_{-0.03}^{+0.03} when using the full data set. The inferred individual virial factor f ∼ 1.6 is moderately smaller than the average factor for a local sample of dynamically modeled AGNs. There is strong evidence for nonvirial motion, with over 70% of clouds on inflowing/outflowing orbits. We analyze the change in model parameters across emission lines, finding the radii of BLRs for the emission lines are consistent with the following relative sizes R H β ≲ R MgII ≲ R H α . Comparing results across time, we find R low-state ≲ R high-state , with the change in BLR size for H β being more significant than for the other two lines. The data also reveal complex, time-evolving, and potentially transient dynamics of the BLR gas over a decade-long timescale, encouraging for future dynamical modeling of fine-scale BLR kinematics.}, archive = {J_ApJ}, author = {Zachary Stone and Yue Shen and Scott F. Anderson and Franz Bauer and W. N. Brandt and Priyanka Chakraborty and Megan C. Davis and Logan B. Fries and Catherine J. Grier and P. B. Hall and Keith Horne and Anton M. Koekemoer and Mary Loli Martínez-Aldama and Knox Long and Sean Morrison and Claudio Ricci and Donald P. Schneider and Matthew J. Temple and Jonathan R. Trump}, doi = {10.3847/1538-4357/adfd4c}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {218}, shortjournal = {The Astrophys. J.}, title = {The SDSS-V black hole mapper reverberation mapping project: Multiline dynamical modeling of a highly variable active galactic nucleus with decade-long light curves}, volume = {991}, year = {2025}, }
• (2025). JWST/NIRSpec observations of high-ionization emission lines in galaxies at high redshift. ApJ, 991(2), 217. (www)

  @article{ , abstract = {JWST spectroscopy has built large emission line samples at z ≳ 4, but it has yet to confidently reveal many galaxies with the hard radiation fields commonly associated with active galactic nucleus photoionization. While this may indicate a weaker UV ionizing spectrum in many z > 4 active galactic nuclei or obscuration from dense neutral gas and dust, the complete picture remains unclear owing to the small number of deep rest-UV spectra. Here, we characterize the strength of high-ionization lines in 53 new galaxies observed with NIRSpec R = 2700 grating spectroscopy. We present new detections of narrow N v λ 1240 in two galaxies. One is a previously confirmed z = 6.98 little red dot (LRD) with broad H β , and the other is a z = 8.72 galaxy with a narrow-line spectrum. Neither source exhibits C iv or He ii emission, indicating large N v /C iv and N v /He ii ratios that may reflect a combination of nitrogen-enhancement and resonant scattering effects. We investigate the incidence of narrow high-ionization lines in a large database of 851 NIRSpec grating spectra, and we separately quantify the fraction of LRDs with narrow high-ionization UV emission lines. Our results likely suggest that hard radiation fields are indeed present in a small subset of LRDs ( 12.{5}_{-10.4}^{+23.7} \% ) and UV-selected galaxies ( 2.{2}_{-1.0}^{+1.7} \% ) at z > 4. The identification of narrow high-ionization lines in the population of LRDs with strong Balmer absorption suggests that the dense neutral hydrogen gas may not uniformly cover the nucleus. The strong N v (coupled with weak C iv and He ii ) suggests that efforts to identify high-ionization lines should extend down in wavelength to the N v doublet.}, archive = {J_ApJ}, author = {Mengtao Tang and Daniel P. Stark and Adèle Plat and Anna Feltre and Harley Katz and Peter Senchyna and Charlotte A. Mason and Lily Whitler and Zuyi Chen and Michael W. Topping}, doi = {10.3847/1538-4357/adfd57}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {217}, shortjournal = {The Astrophys. J.}, title = {JWST/NIRSpec observations of high-ionization emission lines in galaxies at high redshift}, volume = {991}, year = {2025}, }
• (2025). Spatial models of R-process remnants and their γ-ray detectability. ApJ, 991(2), 216. (www)

  @article{ , abstract = {We investigate the detectability of gamma-ray emission from long-lived radioactive isotopes in r -process-enriched remnants, focusing on how assumptions about their spatial distribution introduce uncertainty into detection prospects. Using a suite of physically motivated models for the Galactic distribution of kilonova and supernova remnants, we simulate synthetic remnant populations and compute their time-evolving gamma-ray spectra. We then compare these flux predictions to the sensitivity limits of next-generation instruments such as a Compton Spectrometer and Imager (COSI) and High-Energy X-ray Probe (HEX-P). We find that even under optimistic assumptions, detection probabilities with COSI are extremely low (≪1%), and that marginal improvements are only possible with instruments like HEX-P if prior localization is available. The choice of spatial distribution model can lead to more than an order-of-magnitude variation in expected line fluxes at low instrument sensitivities, underscoring the role of spatial modeling as a dominant source of uncertainty. Nevertheless, instrumental capability remains the fundamental bottleneck, and a hybrid mission combining COSI-like sky coverage with HEX-P-level line sensitivity would be required to make detection more probable than not.}, archive = {J_ApJ}, author = {Benjamin Amend and Christopher L. Fryer and Matthew R. Mumpower and Oleg Korobkin}, doi = {10.3847/1538-4357/adfdde}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {216}, shortjournal = {The Astrophys. J.}, title = {Spatial models of R-process remnants and their γ-ray detectability}, volume = {991}, year = {2025}, }
• (2025). A unified model of solar prominence formation with self-consistent heating. ApJ, 991(2), 215. (www)

  @article{ , abstract = {Several models have been proposed to explain the formation of solar prominences, among which the evaporation–condensation model and the direct injection model are the most popular ones. In our previous study, we proposed to unify these two models: in both models, the formation of solar prominence is due to localized heating, presumably via magnetic reconnection. When the localized heating is located in the upper chromosphere, the cold in situ plasmas are heated to coronal temperatures, then evaporated to the corona, and finally condensate to form a prominence. Such a process is manifested as the evaporation–condensation model. When the localized heating is located in the lower chromosphere, the enhanced in situ pressure would push the cold plasmas in the upper chromosphere to the corona directly, which is manifested as the direct injection model. While the idea was confirmed by the one-dimensional hydrodynamic simulations, the heating was imposed ad hoc. In order to simulate the localized heating more self-consistently, we perform two-dimensional magnetohydrodynamic simulations in this paper, where the localized heating is naturally realized by magnetic reconnection at different heights. The simulations further validate our model. In addition, mass circulation in the solar atmosphere is also briefly discussed.}, archive = {J_ApJ}, author = {C. J. Huang and Y. W. Ni and J. H. Guo and P. F. Chen}, doi = {10.3847/1538-4357/adfe72}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {215}, shortjournal = {The Astrophys. J.}, title = {A unified model of solar prominence formation with self-consistent heating}, volume = {991}, year = {2025}, }
• (2025). Radial evolution of turbulence spectra on the jovian magnetosheath flanks: Juno observations. ApJ, 991(2), 214. (www)

  @article{ , abstract = {The Jovian magnetosheath provides a unique environment for examining the radial evolution of magnetosheath turbulence due to its large spatial extent. Utilizing magnetic field measurements from the Juno spacecraft, this study examines the radial evolution of magnetic field turbulence on the flanks of the Jovian magnetosheath. We find that turbulence on the dawn flank evolves significantly after crossing the bow shock. In contrast, the dusk flank exhibits a flattening of the power spectrum at MHD scales, attributed to the presence of mirror modes. Wave analysis based on the singular value decomposition method confirms the role of mirror modes in causing spectral flattening. Statistical results reinforce the connection between mirror modes and spectral flattening and reveal a dawn–dusk asymmetry in the distribution of mirror modes.}, archive = {J_ApJ}, author = {Hui Li and Haoyu Li and Zhongwei Yang and Chi Wang}, doi = {10.3847/1538-4357/adfed0}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {214}, shortjournal = {The Astrophys. J.}, title = {Radial evolution of turbulence spectra on the jovian magnetosheath flanks: Juno observations}, volume = {991}, year = {2025}, }
• (2025). Wave responses to magnetosheath boundary motion at saturn: Mirror modes and electromagnetic ion cyclotron waves. ApJ, 991(2), 213. (www)

  @article{ , abstract = {Saturn’s magnetosheath provides a natural laboratory for studying the generation and evolution of low-frequency plasma waves that play a key role in regulating temperature anisotropy and mediating wave–particle interactions. Using magnetic field and plasma measurements from the Cassini spacecraft, we investigate the occurrence of mirror mode waves (MMWs) and electromagnetic ion cyclotron (EMIC) waves in relation to the large-scale motion of Saturn’s magnetosheath boundaries, namely, the bow shock and magnetopause. A systematic classification of spacecraft crossings reveals that although MMWs are pervasive across all dynamic conditions, their morphology transitions between peak-like and dip-like structures depending on the direction of boundary motion. EMIC waves occur preferentially during outward motion of the bow shock, particularly on the dawnside, where recent upstream pressure reductions may have driven boundary expansion and formed localized low-beta regions favorable for cyclotron instability. These findings highlight the importance of time-dependent boundary dynamics in shaping the wave environment of planetary magnetosheaths, with broader implications for energy dissipation and plasma stability in rapidly rotating planetary magnetospheres and other astrophysical plasmas with evolving boundaries.}, archive = {J_ApJ}, author = {Xinya Duanmu and Shengyi Ye and Zhonghua Yao}, doi = {10.3847/1538-4357/ae03ba}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {213}, shortjournal = {The Astrophys. J.}, title = {Wave responses to magnetosheath boundary motion at saturn: Mirror modes and electromagnetic ion cyclotron waves}, volume = {991}, year = {2025}, }
• (2025). FEAST: JWST/NIRCam view of the resolved stellar populations of the interacting dwarf galaxies NGC 4485 and NGC 4490. ApJ, 991(2), 212. (www)

  @article{ , abstract = {We present new JWST/NIRCam observations of the interacting dwarf galaxy system NGC 4485–NGC 4490 (aka Arp 269), obtained as part of the Cycle 1 Feedback in Emerging Extragalactic Star Clusters (FEAST) program. NGC 4485 and NGC 4490 form the closest known pair of interacting late-type dwarf galaxies (at ∼7.4 Mpc), excluding the Magellanic Clouds. Near-infrared color–magnitude diagrams (CMDs) reveal a wide range of stellar populations in both galaxies, including young (≲200 Myr) upper main-sequence stars, core helium-burning stars, and oxygen-rich asymptotic giant branch (AGB) stars. We also identify intermediate-age (∼200 Myr–1 Gyr) carbon-rich AGB stars and a well-populated old (≳1 Gyr) red giant branch. The CMDs show two distinct bursts of star formation beginning ∼30 and ∼200 Myr ago, the latter consistent with the most recent pericenter passage predicted by N -body simulations. The spatial distribution of stars reveals a tidal bridge extending from NGC 4485 and connecting to the disk of NGC 4490. Compact star-forming regions are seen along NGC 4490’s spiral arms, possibly originating from its infrared nucleus. A significant metallicity gradient is observed in the young stellar populations forming the bridge. These findings suggest that during the last pericenter passage, gas was stripped from NGC 4485 via tidal forces or ram pressure, accreted by NGC 4490, and mixed with in situ material, fueling ongoing star formation. This system provides a unique nearby laboratory for studying how tidal interactions shape the star formation and chemical enrichment history of dwarf galaxies.}, archive = {J_ApJ}, author = {Giacomo Bortolini and Matteo Correnti and Angela Adamo and Michele Cignoni and Elena Sacchi and Monica Tosi and Göran Östlin and Anastasios Kapodistrias and Arjan Bik and Daniela Calzetti and Ana Duarte-Cabral and Flavia Dell’Agli and John S. Gallagher and Benjamin Gregg and Kathryn Grasha and Thomas S.-Y. Lai and Drew Lapeer and Sean T. Linden and Matteo Messa and Alex Pedrini and Elena Sabbi and Linda J. Smith and Helena Faustino Vieira and John M. Cannon and Salvador Duarte Puertas and Carmelle Robert}, doi = {10.3847/1538-4357/adfccc}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {212}, shortjournal = {The Astrophys. J.}, title = {FEAST: JWST/NIRCam view of the resolved stellar populations of the interacting dwarf galaxies NGC 4485 and NGC 4490}, volume = {991}, year = {2025}, }
• (2025). Improved limits on the 21 cm signal at z = 6.5–7.0 with the murchison widefield array using gaussian information. ApJ, 991(2), 211. (www)

  @article{ , abstract = {We explore the properties of interferometric data from high-redshift 21 cm measurements using the Murchison Widefield Array (MWA). These data contain the redshifted 21 cm signal, contamination from continuum foreground sources, and radiometric noise. The 21 cm signal from the Epoch of Reionization (EoR) is expected to be highly Gaussian, which motivates the use of the power spectrum as an effective statistical tool for extracting astrophysical information. We find that foreground contamination introduces non-Gaussianity into the distribution of measurements and then use this information to separate Gaussian from the non-Gaussian signal. We present improved upper limits on the 21 cm EoR power spectrum from the MWA using a Gaussian component of the data, based on the existing analysis from C. D. Nunhokee et al. 2025. This is extracted as the best-fitting Gaussian to the measured data. Our best 2 σ (thermal+sample variance) limit for 268 hr of data improves from (30.2 mK) 2 to (23.0 mK) 2 at z = 6.5 for the East–West polarization, and from (39.2 mK) 2 to (21.7 mK) 2 = 470 mK 2 in North–South. The best limits at z = 6.8 ( z = 7.0) improve to P < (25.9 mK) 2 ( P < (32.0 mK) 2 ) and k = 0.18 h Mpc −1 ( k = 0.21 h Mpc −1 ). Results are compared with realistic simulations, which indicate that leakage from foreground contamination is a source of the non-Gaussian behavior.}, archive = {J_ApJ}, author = {Cathryn M. Trott and C. D. Nunhokee and D. Null and N. Barry and Y. Qin and R. B. Wayth and J. L. B. Line and C. H. Jordan and B. Pindor and J. H. Cook and J. Bowman and A. Chokshi and J. Ducharme and K. Elder and Q. Guo and B. J. Hazelton and W. Hidayat and T. Ito and D. Jacobs and E. Jong and M. Kolopanis and T. Kunicki and E. Lilleskov and M. F. Morales and J. Pober and A. Selvaraj and R. Shi and K. Takahashi and S. J. Tingay and R. L. Webster and S. Yoshiura and Q. Zheng}, doi = {10.3847/1538-4357/adff80}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {211}, shortjournal = {The Astrophys. J.}, title = {Improved limits on the 21 cm signal at z = 6.5–7.0 with the murchison widefield array using gaussian information}, volume = {991}, year = {2025}, }
• (2025). Gravitational binding and star formation in molecular clouds of the milky way. ApJ, 991(2), 210. (www)

  @article{ , abstract = {The gravitational binding and star-forming properties of molecular clouds in the Milky Way (MW) are estimated from CO cloud observations and from a model of pressure-bounded virial equilibrium (PVE). Two CO surveys are analyzed with the standard CO conversion factor. The main results are as follows. (1) For each survey the cloud virial parameter {\alpha }_{{\rm{vir}}} increases by a factor ~2 from galactocentric radius {R}_{{\rm{gal}}}=4 to 15 kpc. (2) PVE models match these trends only if the surface densities of survey clouds and nearby stars are comparable. This evidence of environmental influence resembles that seen in other disk galaxies. (3) Many survey clouds form stars even though their virial parameter exceeds the critical value {\alpha }_{{\rm{vir}}}\approx 2 . In PVE such clouds with constant velocity dispersion have stable equilibrium and \, cannot form stars by simple global collapse. (4) However, simulations show that {\alpha }_{{\rm{vir}}}\approx 2 clouds with dissipating turbulence may form filaments, cores, and protostars with little global contraction. Such clouds can match the MW star formation rate if their protostellar cores have a mass fraction \sim {10}^{-3} . A simple model predicts that the star-forming age of a cloud is proportional to the ratio of its young stellar objects (YSOs) to its mass. (5) Clouds within 500 pc of the Sun are predicted to have star-forming ages 1–10 Myr and average YSO age ∼2 Myr, matching evolutionary models. The Orion A cloud is predicted to have ∼60 Class 0 protostars, ∼2900 YSOs, and a star formation efficiency SFE \approx \, 0.02, in good agreement with observed estimates.}, archive = {J_ApJ}, author = {Philip C. Myers and Mark Heyer and Ian W. Stephens and Simon Coudé and Nicole Karnath and Howard A. Smith}, doi = {10.3847/1538-4357/adf8e5}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {210}, shortjournal = {The Astrophys. J.}, title = {Gravitational binding and star formation in molecular clouds of the milky way}, volume = {991}, year = {2025}, }
• (2025). Comprehensive statistical analysis of initial lorentz factor and jet opening angle of gamma-ray bursts. ApJ, 991(2), 209. (www)

  @article{ , abstract = {The initial Lorentz factor (Γ 0 ) and jet half-opening angle ( θ jet ) of gamma-ray bursts (GRBs) are critical physical parameters for understanding the dynamical evolution of relativistic jets and the true energy release of GRBs. We compile a sample of 89 GRBs that exhibit an onset bump feature in their early optical or GeV light curves, 42 of which also display a jet break feature, and derive their Γ 0 and θ jet values. Using this sample, we reexamine the correlations between Γ 0 and the prompt emission parameters (isotropic energy E iso , peak luminosity L iso , and peak energy E p ). Our results confirm the previously reported Γ 0 − E iso ( L iso ), Γ 0 − E p,z , and E iso ( L iso )− E p −Γ 0 relations for both homogeneous interstellar medium (ISM) and Wind density profiles (Wind). Notably, we find that the short GRB 090510 complies with the Γ 0 − E iso relation, but significantly deviates from the Γ 0 − L iso and Γ 0 − E p,z relations. We systematically investigate the influence of θ jet on Γ 0 and find a weak dependence, which reads Γ 0 (ISM) ∝ {\theta }_{{\rm{jet}}}^{-0.18\pm 0.15} (ISM) and Γ 0 (Wind) ∝ {\theta }_{{\rm{jet}}}^{-0.72\pm 0.14} (Wind). Additionally, we report, for the first time, three new three-parameter correlations, i.e., {E}_{{\rm{iso}}}\propto {\theta }_{{\rm{jet}}}^{-0.52\pm 0.26} (ISM) {{\rm{\Gamma }}}_{0}^{2.21\pm 0.28} (ISM) and {E}_{{\rm{iso}}}\propto {\theta }_{{\rm{jet}}}^{-0.65\pm 0.21} (Wind) {{\rm{\Gamma }}}_{0}^{2.08\pm 0.19} (Wind); {L}_{{\rm{iso}}}\propto {\theta }_{{\rm{jet}}}^{-0.35\pm 0.27} (ISM) {{\rm{\Gamma }}}_{0}^{2.46\pm 0.29} (ISM) and {L}_{{\rm{iso}}}\propto {\theta }_{{\rm{jet}}}^{-0.29\pm 0.28} (Wind) {{\rm{\Gamma }}}_{0}^{2.37\pm 0.25} (Wind); and {E}_{{\rm{p}},{\rm{z}}}\propto {\theta }_{{\rm{jet}}}^{-0.15\pm 0.19} (ISM) {{\rm{\Gamma }}}_{0}^{1.11\pm 0.21} (ISM) and {E}_{{\rm{p}},{\rm{z}}}\propto {\theta }_{{\rm{jet}}}^{-0.17\pm 0.23} (Wind) {{\rm{\Gamma }}}_{0}^{1.09\pm 0.21} (Wind). These tight E iso (or L iso , E p,z )−Γ 0 − θ jet correlations likely arise from the combined effects of radiation mechanisms, jet structure, and outflow dynamics in GRBs. In addition, we further explore the relations between the initial Lorentz factor and the jet-corrected energy, and find Γ 0 (ISM) ∝ {E}_{\gamma ,52}^{0.22\pm 0.04} (ISM) and Γ 0 (Wind) ∝ {E}_{\gamma ,52}^{0.40\pm 0.06} (Wind); and Γ 0 (ISM) ∝ {L}_{\gamma ,52}^{0.20\pm 0.04} (ISM) and Γ 0 (Wind) ∝ {L}_{\gamma ,52}^{0.30\pm 0.06} (Wind). We also find that the jet-corrected correlations remain significant, suggesting that these relations are intrinsic to the physical nature of GRBs. However, the increased dispersion after correction implies that underlying differences persist among individual GRBs.}, archive = {J_ApJ}, author = {Jian Zhang and Bao-Cheng Qin and Lu-Lu Zhang and Fu-Wen Zhang}, doi = {10.3847/1538-4357/adfc46}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {209}, shortjournal = {The Astrophys. J.}, title = {Comprehensive statistical analysis of initial lorentz factor and jet opening angle of gamma-ray bursts}, volume = {991}, year = {2025}, }
• (2025). Identification of nonlinear damping of transverse loop oscillations by KHI-induced turbulence. ApJ, 991(2), 208. (www)

  @article{ , abstract = {Kink oscillations in coronal loops have been extensively studied for their potential contributions to coronal heating and their role in plasma diagnostics through coronal seismology. A key focus is the strong damping of large-amplitude kink oscillations, which observational evidence suggests is nonlinear. However, directly identifying the nonlinearity is a challenge. This work presents an analytic formula describing nonlinear standing kink oscillations dissipated by turbulence, characterised by a time-varying damping rate and period drift. We investigate how the damping behaviour depends on the driving amplitude and loop properties, showing that the initial damping time τ is inversely proportional to the velocity disturbance over the loop radius, V i / R . Using Markov Chain Monte Carlo fitting with Bayesian inference, the nonlinear function better fits an observed decaying kink oscillation than traditional linear models, including exponential damping, suggesting its nonlinear nature. By applying a Bayesian model comparison, we establish regimes in which nonlinear and linear resonant absorption mechanisms dominate based on the relationship between the damping rate τ / P and V i / R . Additionally, analysis of two specific events reveals that while one favours the nonlinear model, the other is better explained by the linear model. Our results suggest that this analytical approximation of nonlinear damping due to turbulence provides a valid and reliable description of large-amplitude decaying kink oscillations in coronal loops.}, archive = {J_ApJ}, author = {Sihui Zhong and Andrew Hillier and Iñigo Arregui}, doi = {10.3847/1538-4357/adfd5c}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {208}, shortjournal = {The Astrophys. J.}, title = {Identification of nonlinear damping of transverse loop oscillations by KHI-induced turbulence}, volume = {991}, year = {2025}, }
• (2025). Estimating the initial mass of the Gaia–Enceladus dwarf galaxy with a chemical evolution model. ApJ, 991(2), 207. (www)

  @article{ , abstract = {This work investigates the initial mass and chemical evolution history of the Gaia–Enceladus dwarf galaxy. We combine spectroscopic data from APOGEE with astrometric data from Gaia Data Release 3 to identify Gaia–Enceladus candidate stars via a machine learning pipeline using t-SNE and HDBSCAN. By focusing on kinematic and chemical parameters, especially [Fe/H], [Mg/Fe], [Al/Fe], and [Mn/Fe], we uncover a population of metal-poor, high-eccentricity stars that align with literature criteria for Gaia–Enceladus debris. We then apply the OMEGA+ chemical evolution model, incorporating Markov Chain Monte Carlo fitting of the observed abundance trends in the [Mg/Fe]–[Fe/H] plane. Our best-fitting model indicates a gas mass of 4.9{3}_{-0.72}^{+0.32}\times 1{0}^{9}\,{M}_{\odot } for Gaia–Enceladus, placing it at the higher end of previously suggested masses. The model scenario suggests a short star formation timescale, substantial outflows, and a rapid buildup of metals mainly driven by core-collapse supernovae, with a lesser contribution from Type Ia supernovae. Comparison with observational data in other chemical planes (e.g., [Mg/Mn]–[Al/Fe]) supports this scenario, emphasizing a distinct evolution path relative to the Milky Way. Additionally, our results provide indirect evidence that star formation in Gaia–Enceladus likely ceased within the first 4 Gyr, consistent with earlier inferences of an early merger event. These findings highlight the power of chemical evolution modeling in reconstructing the origin and mass of ancient accreted systems. Overall, we show that Gaia–Enceladus, through rapid star formation and strong outflows, contributed a significant fraction of the metal-poor stellar halo of the Milky Way.}, archive = {J_ApJ}, author = {Olcay Plevne and Furkan Akbaba}, doi = {10.3847/1538-4357/adfd5e}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {207}, shortjournal = {The Astrophys. J.}, title = {Estimating the initial mass of the Gaia–Enceladus dwarf galaxy with a chemical evolution model}, volume = {991}, year = {2025}, }
• (2025). The formation of ultra-short-period planets under the influence of the nearby planetary companions. ApJ, 991(2), 206. (www)

  @article{ , abstract = {Ultra-short-period (USP) planets, defined as those with orbital periods shorter than 1 day, provide valuable insights into planetary evolution under strong stellar tidal interactions. In this work, we investigate the formation of USP planets in two-planet systems consisting of an inner terrestrial planet accompanied by an outer hot Jupiter (HJ). Our simulation results show USP planets can form through a process driven by secular perturbations from the outer companion, which induce eccentricity excitation, tidal dissipation, and subsequent orbital decay of the inner planet. The probability of USP formation is governed by key factors, including the mass ratio between two planets, their orbital eccentricities, and the tidal dissipation process. 6.7% of our simulations form USP planets, and USP planets form most efficiently when the mass ratio is around 4 M ⊕ / M J , with the inner planet less than 8 M ⊕ . Furthermore, the eccentricity of the outer HJ plays a crucial role—moderate eccentricities ( e outer < 0.1) favor USP formation, whereas higher eccentricities ( e outer > 0.1) enhance the likelihood of orbital instability, often resulting in a lonely HJ. USP planets form more efficiently when the tidal dissipation function of the inner planet is comparable to the values estimated for terrestrial planets in the solar system. Comparison with observed planetary systems reveals that systems with large mass ratios or nearly circular outer planets tend to produce short-period (SP) planets instead of USP planets. Our findings offer a potential explanation for the most commonly observed system architectures, which predominantly feature either an HJ with an inner SP planet or a lonely HJ.}, archive = {J_ApJ}, author = {Jiajun Zhu and Su Wang and Jianghui Ji and Yao Dong}, doi = {10.3847/1538-4357/adfdd1}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {206}, shortjournal = {The Astrophys. J.}, title = {The formation of ultra-short-period planets under the influence of the nearby planetary companions}, volume = {991}, year = {2025}, }
• (2025). Thermal Sunyaev–Zel’dovich effect in the circumgalactic medium. II. dependence on star formation. ApJ, 991(2), 205. (www)

  @article{ , abstract = {We measure the thermal Sunyaev–Zel’dovich effect in the circumgalactic medium (CGM) of ≈2.5 million M 200 = 10 12−14 M ⊙ WISE × DESI galaxies out to z = 1.2. We split the sample into quiescent (0.7 million) and star-forming (1.8 million) galaxies, exploring the relation between the thermal pressure of the CGM and star formation for the first time. We develop and implement a novel probabilistic approach to cross-correlate the galaxy catalog with the Atacama Cosmology Telescope + Planck data by taking into account the uncertainties in redshift, mass, and star formation rate. The signal-to-noise ratio of the stacked Compton- y value in the CGM varies from 4.9 σ to 18.5 σ , depending on the sample size and the CGM signal strength within the relevant mass bin. We detect the CGM signal down to M 200 = 10 12.3 M ⊙ , and provide a stringent upper limit at M 200 < 10 12.3 M ⊙ . The data fit well with the standard generalized Navarro–Frenk–White profile of thermal pressure and do not require a flatter or steeper profile. This suggests a significant impact of cooling and the absence of dominant feedback. In galaxies with M 200 ≈ 10 12.3−12.8 M ⊙ halos, the volume-filling CGM is likely the largest contributor to the galactic baryons at their virial temperatures of ∼10 6−6.4 K. For M 200 > 10 12.8 ! M ⊙ halos, the most massive phase of the CGM is likely at a subvirial temperature of ≳10 6 K. The thermal energy of the CGM of quiescent galaxies follows the self-similar relation with mass, but the star-forming galaxies deviate from this relation. This indicates that the impact of nongravitational factors varies among halos of different degrees of star-forming activity.}, archive = {J_ApJ}, author = {Sanskriti Das and Nhut Truong and Yi-Kuan Chiang and Smita Mathur}, doi = {10.3847/1538-4357/adfdd6}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {205}, shortjournal = {The Astrophys. J.}, title = {Thermal Sunyaev–Zel’dovich effect in the circumgalactic medium. II. dependence on star formation}, volume = {991}, year = {2025}, }
• (2025). The production mechanism of the high-energy emission line in the brightest cosmic burst. ApJ, 991(2), 204. (www)

  @article{ , abstract = {As a characteristic feature of the spectrum, the emission line carries critical information on the underlying physics of the radiation. After extensive efforts in decades, the first high-significant detection of a series of emission lines evolving from 37 MeV to 6 MeV has been detected in the ever-bright gamma-ray burst GRB 221009A. However, the physical mechanism of the entire evolutionary trend of the lines remains elusive. To provide a self-consistent interpretation, we propose a novel scenario in which the photons of the line undergo a radiation transfer process called down-Comptonization after generation by the electron–positron pair annihilation. By incorporating the gamma-ray burst dynamical evolution, we systematically reproduce the observed evolution of the central energy, width, and flux of the emission line and further impose stringent constraints on the production of high-energy emission lines in general. Our study provides a new direction to the research of extreme cosmic bursts.}, archive = {J_ApJ}, author = {Jieying Liu and Jirong Mao and Shao-Lin Xiong and Yan-Qiu Zhang}, doi = {10.3847/1538-4357/adfd53}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {204}, shortjournal = {The Astrophys. J.}, title = {The production mechanism of the high-energy emission line in the brightest cosmic burst}, volume = {991}, year = {2025}, }
• (2025). CLOUDY and the high-resolution microcalorimeter revolution: Optical, UV, and X-ray spectra of one-electron systems. ApJ, 991(2), 203. (www)

  @article{ , abstract = {With the launch of the XRISM microcalorimeter mission, space-based X-ray observations will achieve a record spectral resolving power of R ≡ E /Δ E ∼ 1200. With this resolving power, emission features associated with fine-structure energy levels of some species will be resolved, sometimes for the first time. The plasma code, Cloudy , was not originally designed for high-resolution X-ray spectroscopy and throughout its history did not resolve fine-structure components of Lyman lines. Here, we expand Cloudy to resolve these fine-structure energy levels and obtain predicted X-ray spectra that match the resolution of new microcalorimeter observations. We show how the Lyman lines can be used as column density indicators in the hot X-ray emitting gas in a cluster of galaxies such as Perseus, and examine their sensitivity to external radiation fields and turbulence.}, archive = {J_ApJ}, author = {Chamani M. Gunasekera and Peter A. M. van Hoof and Marios Chatzikos and Gary J. Ferland}, doi = {10.3847/1538-4357/adfc6c}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {203}, shortjournal = {The Astrophys. J.}, title = {CLOUDY and the high-resolution microcalorimeter revolution: Optical, UV, and X-ray spectra of one-electron systems}, volume = {991}, year = {2025}, }
• (2025). Energy conversion and electron acceleration and transport in 3D simulations of solar flares. ApJ, 991(2), 202. (www)

  @article{ , abstract = {Recent observations and simulations indicate that solar flares undergo extremely complex 3D evolution, making 3D particle transport models essential for understanding electron acceleration and interpreting flare emissions. In this study, we investigate this problem by solving Parker’s transport equation with 3D MHD simulations of solar flares. By examining energy conversion in the 3D system, we evaluate the roles of different acceleration mechanisms, including reconnection current sheet (CS), termination shock (TS), and supra-arcade downflows (SADs). We find that large-amplitude turbulent fluctuations are generated and sustained in the 3D system. The model results demonstrate that a significant number of electrons are accelerated to hundreds of keV and even a few MeV, forming power-law energy spectra. These energetic particles are widely distributed, with concentrations at the TS and in the flare looptop region, consistent with results derived from recent hard X-ray (HXR) and microwave (MW) observations. By selectively turning particle acceleration on or off in specific regions, we find that the CS and SADs effectively accelerate electrons to several hundred keV, while the TS enables further acceleration to MeV. However, no single mechanism can independently account for the significant number of energetic electrons observed. Instead, the mechanisms work synergistically to produce a large population of accelerated electrons. Our model provides spatially and temporally resolved electron distributions in the whole flare region and at the flare footpoints, enabling synthetic HXR and MW emission modeling for comparison with observations. These results offer important insights into electron acceleration and transport in 3D solar flare regions.}, archive = {J_ApJ}, author = {Xiaocan Li and Chengcai Shen and Xiaoyan Xie and Fan Guo and Bin Chen and Ivan Oparin and Yuqian Wei and Sijie Yu and Jeongbhin Seo}, doi = {10.3847/1538-4357/adfcd5}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {202}, shortjournal = {The Astrophys. J.}, title = {Energy conversion and electron acceleration and transport in 3D simulations of solar flares}, volume = {991}, year = {2025}, }
• (2025). RRAT j2325–0530: A rotating radio transient with an atypical waiting-time distribution. ApJ, 991(2), 201. (www)

  @article{ , abstract = {We present 1.25 GHz observations of the rotating radio transient (RRAT) J2325–0530, conducted with the Five-hundred-meter Aperture Spherical radio Telescope. Approximately 60% of detected single pulses occur in clusters of two to five consecutive bursts. Consequently, the waiting-time distribution between successive single pulses exhibits a pronounced excess at one rotation period, deviating from the exponential distribution expected for a Poisson process. After grouping consecutive bursts into single emission events, the recalculated waiting-time distribution is well described by a Weibull distribution with a shape parameter k ≳ 1. Monte Carlo simulations incorporating both intrinsic burst on-windows and rotational modulation successfully reproduce the observed one-rotation excess. These results suggest that RRAT J2325–0530 emits through a quasi-random process with on-windows slightly longer than its spin period, modulated by the rotation of the emission beam. Additionally, the polarization position angle shows complex behavior that cannot be fully described by the standard rotating vector model, and several pulses exhibit quasiperiodic microstructures. Taken together, these features indicate complex magnetospheric dynamics underlying the sporadic emission behavior of RRAT J2325–0530.}, archive = {J_ApJ}, author = {Shi-Jie Gao and Xiang-Dong Li and Zhen Yan and Yi-Xuan Shao and Ping Zhou}, doi = {10.3847/1538-4357/adff5b}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {201}, shortjournal = {The Astrophys. J.}, title = {RRAT j2325–0530: A rotating radio transient with an atypical waiting-time distribution}, volume = {991}, year = {2025}, }
• (2025). Elemental and isotopic yields from t coronae borealis: Predictions and uncertainties. ApJ, 991(2), 200. (www)

  @article{ , abstract = {T Coronae Borealis (T CrB) is a symbiotic recurrent nova system expected to undergo its next outburst within the next 2 yr. Recent hydrodynamic simulations have predicted the nucleosynthetic yields for both carbon–oxygen (CO) and oxygen–neon (ONe) white-dwarf models, but without accounting for thermonuclear reaction rate uncertainties. We perform detailed Monte Carlo postprocessing nucleosynthesis calculations based on updated thermonuclear reaction rates and uncertainties from the 2025 evaluation. We quantify the resulting abundance uncertainties and identify the key nuclear reactions that dominate them. Our results show that both the CO and ONe nova models robustly produce characteristic CNO isotopes. More pronounced abundance differences emerge for elements with A ≥ 20. Sulfur is the most robust observational discriminator between the CO and ONe nova models, with a model-to-model difference of a factor of ≈30 and minimal sensitivity to reaction rate uncertainties. Neon, silicon, and phosphorus exhibit even larger abundance differences (factors of ≈150–250), providing strong diagnostic potential. While their predicted yields are subject to larger uncertainties, these remain smaller than the model-to-model differences, allowing these elements to serve as useful, though less precise, tracers of white-dwarf composition. Chlorine, argon, and potassium also differ between models, but the 1 σ -abundance ranges for the CO and ONe models overlap, reducing their present usefulness as composition tracers. We find that only nine nuclear reactions dominate the abundance uncertainties of the most diagnostically important isotopes, and their influence is largely independent of the underlying white-dwarf composition. These results provide guidance for future experimental efforts and for interpreting ejecta compositions in the next eruption of T CrB.}, archive = {J_ApJ}, author = {Emma Wallace and Christian Iliadis and Sumner Starrfield}, doi = {10.3847/1538-4357/ae00bd}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {200}, shortjournal = {The Astrophys. J.}, title = {Elemental and isotopic yields from t coronae borealis: Predictions and uncertainties}, volume = {991}, year = {2025}, }
• (2025). Searching for historical extragalactic optical transients associated with fast radio bursts. ApJ, 991(2), 199. (www)

  @article{ , abstract = {We present a systematic search for past supernovae (SNe) and other historical optical transients at the positions of fast radio burst (FRB) sources to test FRB progenitor systems. Our sample comprises 83 FRBs detected by the Canadian Hydrogen Intensity Mapping Experiment (CHIME) and its k’niʔatn k’l ⌣ stk’masqt Outrigger, along with 93 literature FRBs representing all known well-localized FRBs. We search for optical transients coincident in position and redshift with FRBs and find no significant associations within the 5 σ FRB localization uncertainties except for a previously identified potential optical counterpart to FRB 20180916B. By constraining the timescale for SN ejecta to become transparent to FRB emission, we predict that it takes at least 6–10 yr before the FRB emission can escape. From this, we infer that ≈7% of matched optical transients, up to 30% of currently known SNe, and up to 40% of core-collapse SNe could have an observable FRB based on timescales alone. We derive the number of new, well-localized FRBs required to produce one FRB-SN match by chance, and find it will take ∼22,700 FRBs to yield one chance association at the projected CHIME/FRB Outrigger detection rate. Looking forward, we demonstrate redshift overlap between SNe detected by the upcoming Vera C. Rubin Observatory and CHIME/FRB Outrigger FRBs, indicating the prospect of an increase in potential associations at redshift z < 1. Our framework is publicly available, flexible to a wide range of transient timescales and FRB localization sizes, and can be applied to any optical transient populations in future searches.}, archive = {J_ApJ}, author = {Y. Dong and C. D. Kilpatrick and W. Fong and A. P. Curtin and S. Opoku and B. C. Andersen and A. M. Cook and T. Eftekhari and E. Fonseca and B. M. Gaensler and R. C. Joseph and J. F. Kaczmarek and L. A. Kahinga and V. Kaspi and A. E. Lanman and M. Lazda and C. Leung and K. W. Masui and D. Michilli and K. Nimmo and A. Pandhi and A. B. Pearlman and M. Sammons and P. Scholz and V. Shah and K. Shin and K. Smith}, doi = {10.3847/1538-4357/adfb74}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {199}, shortjournal = {The Astrophys. J.}, title = {Searching for historical extragalactic optical transients associated with fast radio bursts}, volume = {991}, year = {2025}, }
• (2025). Quantification of the age dependence of mid-infrared star formation rate indicators. ApJ, 991(2), 198. (www)

  @article{ , abstract = {We combine James Webb Space Telescope images of the nearby galaxy NGC 5194 in the hydrogen recombination line Pa α (1.8756 μ m) from the Cycle 1 program JWST-FEAST with 21 μ m dust continuum images from the Cycle 2 Treasury program JWGT to quantify the difference in the calibration of mid-infrared star formation rates (SFRs) between H II regions and galaxies. We use archival Hubble Space Telescope H α imaging to correct the Pa α emission for the effects of dust attenuation. Our data confirm previous results that the dust-corrected Pa α flux is tightly correlated with the 21 μ m emission at the scales of H II regions. When combined with published JWST data for the H II regions of the galaxy NGC 628 and Spitzer Space Telescope 24 μ m data for whole galaxies and for kiloparsec-size galaxy regions, we show that the L (24)– L (Pa α ) relation has exponent > 1 across six decades in luminosity. In addition, the hybrid 24 μ m + H α SFR indicator has a scaling constant about 4.4 times higher for H II regions than for whole galaxies, also in agreement with previous results. Models of stellar populations with a range of star formation histories reveal that the observed trends can be entirely ascribed to and quantified with the contribution to the infrared emission by stellar populations older than ∼5–6 Myr. Based on the models’ results, we provide (1) a calibration for the infrared SFR across 6 orders of magnitude in L (24), from H II regions to luminous galaxies, and (2) a prescription for the scaling constant of the hybrid infrared SFR indicators as a function of the star formation timescale.}, archive = {J_ApJ}, author = {Daniela Calzetti and Robert C. Kennicutt and Angela Adamo and Karin Sandstrom and Daniel A. Dale and Bruce Elmegreen and John S. Gallagher and Benjamin Gregg and Varun Bajaj and Torsten Böker and Giacomo Bortolini and Martha Boyer and Matteo Correnti and Ilse De Looze and Bruce T. Draine and Ana Duarte-Cabral and Helena Faustino Vieira and Kathryn Grasha and L. K. Hunt and Kelsey E. Johnson and Ralf S. Klessen and Mark R. Krumholz and Thomas S.-Y. Lai and Drew Lapeer and Sean T. Linden and Matteo Messa and Göran Östlin and Alex Pedrini and Mònica Relaño and Elena Sabbi and Eva Schinnerer and Evan Skillman and Linda J. Smith and Monica Tosi and Fabian Walter and Tony D. Weinbeck}, doi = {10.3847/1538-4357/adfbe0}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {198}, shortjournal = {The Astrophys. J.}, title = {Quantification of the age dependence of mid-infrared star formation rate indicators}, volume = {991}, year = {2025}, }
• (2025). SQ-A: A collision-triggered starburst in the intragroup medium of stephan’s quintet. ApJ, 991(2), 197. (www)

  @article{ , abstract = {We present new observational evidence supporting the hypothesis that SQ-A, a starburst in the intragroup medium (IGrM) of Stephan’s Quintet (SQ), is triggered by a high-speed collision between two gas systems, one associated with the IGrM ( v ∼ 6900 km s −1 ) and another with the intruder galaxy NGC 7318b ( v ∼ 6000 km s −1 ). The new CO(2–1) data set from the Atacama Large Millimeter/submillimeter Array has angular resolutions between 0\mathop{.}\limits^{^{\prime\prime} }2 and 7\mathop{.}\limits^{^{\prime\prime} }0 and the new Very Large Array H i data cube has an angular resolution of 6\mathop{.}\limits^{^{\prime\prime} }6\times 7\mathop{.}\limits^{^{\prime\prime} }9 . The CO maps show that the two gas systems are bridged by another system with an intermediate velocity of ∼6600 km s −1 , whereas the H i data show that the component of v ∼ 6600 km s −1 fits well into a gap in the more extended v ∼ 6000 km s −1 component, albeit with a displacement of ∼5 kpc. Both the bridge and the complementary distributions between different gas systems are common features of starbursts triggered by cloud–cloud collision. An analysis of clumps (sizes of 100–200 pc) reveals very diversified star formation (SF) activity in clumps belonging to different kinematic systems, with the molecular gas depletion time of the v ∼ 6900 km s −1 clumps being more than 10 times longer than that of the v ∼ 6600 km s −1 clumps. The results are consistent with a scenario in which the enhanced SF activity (and the starburst) in the system of v ∼ 6600 km s −1 is due to gas compression generated in cloud–cloud collisions, whereas the suppression of SF in the v ∼ 6900 km s −1 system is due to vortices (i.e. gas rotation) generated in more complex collisions involving dense clouds and diffuse intercloud gas associated with high-speed shocks.}, archive = {J_ApJ}, author = {C. K. Xu and C. Cheng and M. S. Yun and P. N. Appleton and B. H. C. Emonts and J. Braine and S. C. Gallagher and P. Guillard and U. Lisenfeld and E. O’Sullivan and F. Renaud and P. Aromal and P.-A. Duc and A. Labiano and A. Togi}, doi = {10.3847/1538-4357/adfbf6}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {197}, shortjournal = {The Astrophys. J.}, title = {SQ-A: A collision-triggered starburst in the intragroup medium of stephan’s quintet}, volume = {991}, year = {2025}, }
• (2025). Proton temperature and density variations in linear magnetic holes in the solar wind. ApJ, 991(2), 196. (www)

  @article{ , abstract = {Linear magnetic holes (LMHs) are pressure-balanced structures characterized by reduced magnetic pressure and compensatory thermal pressure enhancements, driven by proton temperature and/or density variations. Here we systematically investigate the relative contributions of the proton temperature and density to the thermal pressure by examining LMH characteristics separately in high-speed and low-speed solar wind streams. Using Solar Orbiter data (2020–2024), we analyze 348 LMHs (∼4.5–5.0 day –1 ; 256 in low-speed and 92 in high-speed streams) identified via a combined partial variance of increments and minimum variance analysis method. Based on their thermal pressure contributions, the selected LMHs are classified into four types: temperature-dominant (T-LMHs), density-dominant (N-LMHs), temperature-and-density-enhanced (TN-LMHs), and background-like (BG-LMHs). We find that in low-speed streams, BG-LMHs are the most common (39%), followed by T-LMHs (25%). In high-speed streams, TN-LMHs are the most frequent (32%). For the first time, we introduce magnetic variance rate (MVR, the normalized temporal gradient of magnetic strength) to quantify phase steepness and a thermal dominance coefficient (TDC, the difference between normalized temperature and density perturbations) to assess the temperature contribution. The results reveal a statistically significant correlation between MVR and TDC exclusively in T-LMHs within low-speed streams (Spearman’s r = 0.4056, P = 0.0009), while other types and high-speed streams show no correlation ( r < 0.23, P > 0.14). This selective correlation supports the role of ponderomotive forces—generated by steepening of nonlinear Alfvén waves—in heating T-LMHs, particularly in compressible low-speed wind environments. These results provide the first observational evidence linking phase-steepening dynamics to thermal enhancements in LMHs.}, archive = {J_ApJ}, author = {RuiHui Yu and Xin Wang and Hua Zhang and Yu Zhang}, doi = {10.3847/1538-4357/adfe6f}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {196}, shortjournal = {The Astrophys. J.}, title = {Proton temperature and density variations in linear magnetic holes in the solar wind}, volume = {991}, year = {2025}, }
• (2025). Prospects for kSZ2–21 cm2 cross correlations during reionization. ApJ, 991(2), 195. (www)

  @article{ , abstract = {The 21 cm line and the patchy kinetic Sunyaev–Zel’dovich (kSZ) effect are promising and complementary probes of the Epoch of Reionization. A challenge for cross correlating these two signals is that foreground avoidance or removal algorithms applied to the 21 cm data inevitably sacrifice Fourier modes with long wavelengths along the line of sight (i.e., low- k ∥ modes), yet only these same modes contribute to the kSZ signal. Here we show that a suitable kSZ 2 × 21 cm 2 cross-correlation statistic nevertheless remains nonvanishing, even after filtering out the corrupted low- k ∥ Fourier modes from the 21 cm data. We simulate the kSZ 2 × 21 cm 2 cross-correlation signal across reionization-era redshifts and find distinctive redshift evolution. This signal peaks early in the reionization history, when the volume-averaged fraction is around 0.1 ≲ x HII ≲ 0.2, after which it changes sign and reaches a minimum near reionization’s midpoint ( x HII ∼ 0.5), while the signal gradually vanishes as reionization completes. These trends appear generic across three simulated models which differ in their reionization histories. We forecast the detectability of the kSZ 2 × 21 cm 2 cross-power spectrum for the HERA and SKA1-Low 21 cm experiments in combination with current and next-generation cosmic microwave background (CMB) surveys including the Simons Observatory, CMB-S4, and CMB-HD. We find that a high-significance detection (signal-to-noise ratio ≳ 5 σ ) is possible with SKA1-Low and CMB-S4.}, archive = {J_ApJ}, author = {Meng Zhou and Paul La Plante and Adam Lidz and Yi Mao and Yin-Zhe Ma}, doi = {10.3847/1538-4357/adfb67}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {195}, shortjournal = {The Astrophys. J.}, title = {Prospects for kSZ2–21 cm2 cross correlations during reionization}, volume = {991}, year = {2025}, }
• (2025). Magnetosonic waves as a potential driver of observed temperature fluctuation patterns in AGN accretion disks. ApJ, 991(2), 194. (www)

  @article{ , abstract = {Recent observations have revealed slow, coherent temperature fluctuations in AGN disks that propagate both inward and outward at velocities of ∼0.01–0.1 c , a kind of variability that is distinct from reverberation (mediated by the reprocessing of light) between different regions of the disk. We investigate the origin and nature of these fluctuations using global 3D radiation–magnetohydrodynamic simulations of radiation- and magnetic-pressure-dominated AGN accretion disks. Disks with a significant turbulent Maxwell stress component exhibit wave-like temperature perturbations, most evident close to the midplane, whose propagation speeds exactly match the local fast magnetosonic speed and are consistent with the speeds inferred in observations. These fluctuations have amplitudes of 2%–4% in gas temperature, which are also consistent with observational constraints. Disks that are dominated by mean-field Maxwell stresses do not exhibit such waves. While waves may be present in the body of the disk, we do not find them to be present in the photosphere. Although this may in part be due to low numerical resolution in the photosphere region, we discuss the physical challenges that must be overcome for the waves to manifest there. In particular, the fact that such waves are observed implies that the disk photospheres must be magnetically dominated, since radiative damping from photon diffusion smooths out radiation pressure fluctuations. Furthermore, the gas and radiation fluctuations must be out of local thermodynamic equilibrium.}, archive = {J_ApJ}, author = {Ish Kaul and Omer Blaes and Yan-Fei Jiang and Lizhong Zhang}, doi = {10.3847/1538-4357/adfd51}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {194}, shortjournal = {The Astrophys. J.}, title = {Magnetosonic waves as a potential driver of observed temperature fluctuation patterns in AGN accretion disks}, volume = {991}, year = {2025}, }
• (2025). Exploration of the near-infrared colors of cold y dwarfs from the ground and space. ApJ, 991(2), 193. (www)

  @article{ , abstract = {The James Webb Space Telescope (JWST) has provided critical mid-infrared data for cold brown dwarfs. It has also provided low-resolution near-infrared spectra, and for faint sources these are the first spectra at these wavelengths. We use these data and other literature sources to synthesize near-infrared photometry on the Mauna Kea Observatories (MKO) system for 19 T and Y dwarfs, on the Euclid system for 44 T and Y dwarfs, and on the Roman systems for 48 T and Y dwarfs. We also synthesize Euclid I E magnitudes for 15 T and Y dwarfs. Using the S. A. Beiler et al. ( 2024 ) observational effective temperatures ( T eff ), together with ATMO 2020++ model colors, we show that the absolute 4.6 μ m magnitude can be used as a proxy for T eff . We present a polynomial fit to the M W2 : T eff relationship for cool dwarfs with 250 ≲ T eff K ≲ 1000. We select five Y dwarfs with 275 ≲ T eff K ≲ 400 that have a range in near- to mid-infrared colors. Comparison of the JWST spectral energy distribution to ATMO 2020++ models indicate that Y dwarfs that are bluer in J − W2 are lower gravity or more metal rich than their redder counterparts, with stronger CO and CO 2 absorption at 4.2 ≲ λ μ m ≲ 4.9. The near-infrared color diagrams show significant scatter, with complex dependencies on T eff , metallicity, and gravity. In order to disentangle these effects, opacity sources for cool model atmospheres need to be more complete at λ < 1 μ m.}, archive = {J_ApJ}, author = {S. K. Leggett and Mark W. Phillips and Pascal Tremblin}, doi = {10.3847/1538-4357/adf21f}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {193}, shortjournal = {The Astrophys. J.}, title = {Exploration of the near-infrared colors of cold y dwarfs from the ground and space}, volume = {991}, year = {2025}, }
• (2025). HAWC, VERITAS, fermi-LAT, and XMM-newton follow-up observations of the unidentified ultra-high-energy gamma-ray source LHAASO j2108+5157. ApJ, 991(2), 192. (www)

  @article{ , abstract = {We report observations of the ultra-high-energy gamma-ray source LHAASO J2108+5157, utilizing VERITAS, HAWC, Fermi-LAT, and XMM-Newton. VERITAS has collected ∼40 hr of data that we used to set ULs to the emission above 200 GeV. The HAWC data, collected over ∼2400 days, reveal emission between 3 and 146 TeV, with a significance of 7.5 σ , favoring an extended source model. The best-fit spectrum measured by HAWC is characterized by a simple power law with a spectral index of 2.45 ± 0.11 stat . Fermi-LAT analysis finds a point source with a very soft spectrum in the LHAASO J2108+5157 region, consistent with the 4FGL-DR3 catalog results. The XMM-Newton analysis yields a null detection of the source in the 2–7 keV band. The broadband spectrum can be interpreted as a pulsar and a pulsar wind nebula system, where the GeV gamma-ray emission originates from an unidentified pulsar, and the X-ray and TeV emissions are attributed to synchrotron radiation and inverse Compton scattering of electrons accelerated within a pulsar wind nebula. In this leptonic scenario, our X-ray upper limit provides a stringent constraint on the magnetic field, which is ≲1.5 μ G.}, archive = {J_ApJ}, author = {C. B. Adams and P. Bangale and W. Benbow and J. H. Buckley and Y. Chen and J. L. Christiansen and A. J. Chromey and M. Escobar Godoy and S. Feldman and Q. Feng and J. Foote and L. Fortson and A. Furniss and W. Hanlon and O. Hervet and C. E. Hinrichs and J. Holder and Z. Hughes and T. B. Humensky and W. Jin and P. Kaaret and M. Kertzman and M. Kherlakian and D. Kieda and T. K. Kleiner and N. Korzoun and S. Kumar and M. J. Lang and M. Lundy and G. Maier and M. J. Millard and P. Moriarty and R. Mukherjee and W. Ning and R. A. Ong and M. Pohl and E. Pueschel and J. Quinn and P. L. Rabinowitz and K. Ragan and P. T. Reynolds and D. Ribeiro and E. Roache and I. Sadeh and L. Saha and G. H. Sembroski and R. Shang and D. Tak and A. K. Talluri and J. V. Tucci and J. Valverde and D. A. Williams and S. L. Wong and J. Woo and (The VERITAS collaboration) and R. Alfaro and C. Alvarez and J. C. Arteaga-Velázquez and D. Avila Rojas and R. Babu and E. Belmont-Moreno and A. Bernal and K. S. Caballero-Mora and A. Carramiñana and S. Casanova and U. Cotti and J. Cotzomi and E. De la Fuente and C. de León and D. Depaoli and P. Desiati and N. Di Lalla and R. Diaz Hernandez and M. A. DuVernois and K. Engel and T. Ergin and C. Espinoza and K. L. Fan and N. Fraija and S. Fraija and J.A. García-González and F. Garfias and A. Gonzalez Muñoz and M. M. González and J. A. Goodman and S. Groetsch and J. P. Harding and S. Hernández-Cadena and I. Herzog and D. Huang and F. Hueyotl-Zahuantitla and P. Hüntemeyer and A. Iriarte and S. Kaufmann and A. Lara and J. Lee and H. León Vargas and A. L. Longinotti and G. Luis-Raya and K. Malone and O. Martinez and J. Martínez-Castro and J. A. Matthews and P. Miranda-Romagnoli and J. A. Morales-Soto and E. Moreno and M. Araya and M. Mostafá and M. Najafi and A. Nayerhoda and L. Nellen and N. Omodei and E. Ponce and E. G. Pérez-Pérez and C. D. Rho and D. Rosa-González and M. Roth and H. Salazar and A. Sandoval and M. Schneider and J. Serna-Franco and A. J. Smith and Y. Son and R. W. Springer and O. Tibolla and K. Tollefson and I. Torres and R. Torres-Escobedo and R. Turner and F. Ureña-Mena and E. Varela and L. Villaseñor and X. Wang and Z. Wang and I. J. Watson and H. Wu and S. Yu and S. Yun-Cárcamo and H. Zhou and M. Martin and (The HAWC collaboration) and Kaya Mori and Charles J. Hailey and Samar Safi-Harb and Shuo Zhang and (The XMM-Newton collaboration)}, doi = {10.3847/1538-4357/adf439}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {192}, shortjournal = {The Astrophys. J.}, title = {HAWC, VERITAS, fermi-LAT, and XMM-newton follow-up observations of the unidentified ultra-high-energy gamma-ray source LHAASO j2108+5157}, volume = {991}, year = {2025}, }
• (2025). Leonessa: An extremely metal-poor galaxy undergoing secular chemical evolution*. ApJ, 991(2), 191. (www)

  @article{ , abstract = {Extremely metal-poor (XMP) galaxies are systems with gas-phase oxygen abundances below ∼5% solar metallicity (12+log(O/H) ≤ 7.35). These galaxies populate the metal-poor end of the mass–metallicity and luminosity–metallicity relations (MZR and LZR, respectively). Recent studies have found XMP galaxies in the nearby Universe to be outliers on the LZR, where they show enhanced luminosities relative to other galaxies of similar gas-phase oxygen abundance. Here, we present a study of the recently discovered XMP galaxy Leonessa and characterize the system’s properties using new imaging from the Hubble Space Telescope and spectra from the Green Bank Telescope and Hobby–Eberly Telescope. We use these observations to measure a tip of the red giant branch distance (15.86 ± 0.78 Mpc) to Leonessa, the H i gas mass, the gas-phase oxygen abundance, and N/O ratio. We find Leonessa is an isolated, gas-rich (gas fraction μ = 0.69), low-mass (log( M ⋆ / M ⊙ ) = 6.12 ± 0.08), XMP (12+log(O/H) = 7.32 ± 0.04), star-forming galaxy at a distance of 15.86 ± 0.78 Mpc. Our measurements show that Leonessa agrees with the MZR, but disagrees with the LZR; we conclude the LZR offset is due to recent star formation enhancing the system’s luminosity. To investigate possible chemical evolution pathways for nearby XMP galaxies, we also compile a comparison sample of 150 dwarf galaxies (53 XMP systems) taken from the literature with gas-phase metallicity measurements based on the direct method. We find evidence for an anticorrelation between gas-phase oxygen abundance and H i gas-to-stellar mass ratios. We posit Leonessa is undergoing a chemical evolution pathway typical of field dwarf galaxies.}, archive = {J_ApJ}, author = {Joseph A. Breneman and Kristen B. W. McQuinn and Alexander Menchaca and Danielle A. Berg and O. Grace Telford and Max J. B. Newman and Andrew Dolphin and Gregory R. Zeimann}, doi = {10.3847/1538-4357/adf84b}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {191}, shortjournal = {The Astrophys. J.}, title = {Leonessa: An extremely metal-poor galaxy undergoing secular chemical evolution*}, volume = {991}, year = {2025}, }
• (2025). Resolution-corrected white dwarf gravitational redshifts validate fifth-generation sloan digital sky survey wavelength calibration and enable accurate Mass–Radius tests. ApJ, 991(2), 190. (www)

  @article{ , abstract = {Leveraging the large sample size of low-resolution spectroscopic surveys to constrain white dwarf stellar structure requires an accurate understanding of the shapes of hydrogen absorption lines, which are pressure broadened by the Stark effect. Using data from both the Sloan Digital Sky Survey (SDSS) and the Type Ia Supernova Progenitor Survey, we show that substantial biases (5–15 km s −1 ) exist in radial velocity measurements made from observations at low spectral resolution relative to similar measurements from high-resolution spectra. Our results indicate that the physics of line formation in high-density plasmas, especially in the wings of the lines, are not fully accounted for in state-of-the-art white dwarf model atmospheres. We provide corrections to account for these resolution-induced redshifts in a way that is independent of an assumed mass–radius relation, and we demonstrate that statistical measurements of gravitational redshift with these corrections yield improved agreement with theoretical mass–radius relations. Our results provide a set of best practices for white dwarf radial velocity measurements from low-resolution spectroscopy, including those from SDSS, the Dark Energy Spectroscopic Instrument, the 4 m Multi-Object Spectroscopic Telescope, and the Wide-Field Multiplexed Spectroscopic Facility.}, archive = {J_ApJ}, author = {Stefan M. Arseneau and J. J. Hermes and Nadia L. Zakamska and Kareem El-Badry and Nicole R. Crumpler and Vedant Chandra and Gautham Adamane Pallathadka and Carles Badenes and Boris T. Gänsicke and Nicola Gentile Fusillo}, doi = {10.3847/1538-4357/adf8dd}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {190}, shortjournal = {The Astrophys. J.}, title = {Resolution-corrected white dwarf gravitational redshifts validate fifth-generation sloan digital sky survey wavelength calibration and enable accurate Mass–Radius tests}, volume = {991}, year = {2025}, }
• (2025). The BINGO/ABDUS project: Forecast for cosmological parameters from a mock fast radio burst survey. ApJ, 991(2), 189. (www)

  @article{ , abstract = {There are various surveys that will provide excellent data to search for and localize fast radio bursts (FRBs). The BINGO project will be one such survey, and this collaboration has already estimated an FRB detection rate that the project will yield. We present a forecast of the future constraints on our current cosmological model that the BINGO FRB detections and localizations will have when added to other current cosmological data sets. We quantify the dispersion measure (DM) as a function of redshift ( z ) for the BINGO FRB mock sample. Furthermore, we use current data sets (supernova, baryonic acoustic oscillation, and cosmic microwave background data) prior to assessing the efficacy of constraining dark energy models using Monte Carlo methods. Our results show that a spatially localized BINGO FRB data set will provide promising constraints on the population of host galaxies' intrinsic DM and be able to measure the nuisance parameters present within an FRB cosmological analysis. They will also provide alternative estimates on other parameters such as the Hubble constant and the dark energy equation of state. In particular, we should see that BINGO FRB data can put constraints on the degenerate w − H 0 plane, which the cosmic microwave background is incapable of measuring, allowing FRBs to be a viable alternative to baryonic acoustic oscillation to constrain the dark energy equation of state. We conclude that FRBs remain a promising future probe for cosmology and that the FRBs localized by the BINGO project will contribute significantly to our knowledge of the current cosmological model.}, archive = {J_ApJ}, author = {Xue Zhang and Yu Sang and Gabriel A. Hoerning and Filipe B. Abdalla and Elcio Abdalla and Amilcar Queiroz and André A. Costa and Ricardo G. Landim and Chang Feng and Bin Wang and Marcelo V. dos Santos and Thyrso Villela and Carlos A. Wuensche and Jiajun Zhang and Edmar C. Gurjão and Alessandro Marins and Alexandre J. R. Serres and Linfeng Xiao}, doi = {10.3847/1538-4357/adfa11}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {189}, shortjournal = {The Astrophys. J.}, title = {The BINGO/ABDUS project: Forecast for cosmological parameters from a mock fast radio burst survey}, volume = {991}, year = {2025}, }
• (2025). Metal-poor star-forming clumps in cosmic noon galaxies: Evidence for gas inflow and chemical dilution using JWST NIRISS. ApJ, 991(2), 188. (www)

  @article{ , abstract = {The formation and evolution of galaxies are intricately linked to the baryon cycle, which fuels star formation while shaping chemical abundances within galaxies. Investigating the relationship between star formation and metallicity for large samples of galaxies requires expensive IFU surveys or sophisticated tools to analyze grism data. Here we analyze JWST NIRISS slitless grism data using Sleuth , a tool that forward models and infers spatially resolved physical properties from grism data, including observations from JWST NIRISS/NIRCam and future grism data like that from the Roman Space Telescope. Sleuth enables the extraction of high-quality emission line maps from slitless spectra, overcoming contamination and spatially varying stellar populations, which previously limited such studies. Utilizing Sleuth with data from the Canadian NIRISS Unbiased Cluster Survey, we investigated the relationship between metallicity and star formation in the star-forming clumps of galaxies at 0.6 < z < 1.35. We analyzed a sample of 20 galaxies, extracted high-quality emission line maps with Sleuth , and analyzed, in detail, the spatially resolved properties of star-forming clumps. Using H α , [S II ], and [S III ] emission line maps, we examined the spatially resolved metallicities, ionization, and star formation rates of our sample. Our findings reveal that these star-forming clumps show lower metallicities (∼0.1 dex) than their surrounding galactic environments, indicating a metallicity dilution of 20% within the clumps’ gas. Our analysis indicates that these clumps exhibit intensified star formation and reduced metallicity, likely due to the inflow of metal-poor gas. These clumps illustrate the dynamic relationship between star formation and chemical enrichment within galaxies.}, archive = {J_ApJ}, author = {Vicente Estrada-Carpenter and Marcin Sawicki and Roberto Abraham and Yoshihisa Asada and Maruša Bradač and Gabe Brammer and Guillaume Desprez and Kartheik G. Iyer and Nicholas S. Martis and Adam Muzzin and Gaël Noirot and Gregor Rihtaršič and Ghassan T. E. Sarrouh and Chris J. Willott and Jeremy Favaro and Vladan Markov and Rosa M. Mérida and Katherine Myers and Visal Sok}, doi = {10.3847/1538-4357/adfb64}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {188}, shortjournal = {The Astrophys. J.}, title = {Metal-poor star-forming clumps in cosmic noon galaxies: Evidence for gas inflow and chemical dilution using JWST NIRISS}, volume = {991}, year = {2025}, }
• (2025). Properties of turbulent convection and large-scale flows in a rotating F-type star revealed by 3D realistic radiative hydrodynamic simulations. ApJ, 991(2), 187. (www)

  @article{ , abstract = {The nonlinear coupling between stellar convection and rotation is of great interest because it relates to understanding both stellar evolution and activity. We investigate the influence of rotation and the Coriolis force on the dynamics and thermodynamic structure of an F-type main-sequence star with a shallow outer convection zone. We perform a series of 3D radiative hydrodynamic simulations of a 1.47 M ⊙ star for different rotation rates (periods of rotation 1 and 14 days) and with local computational domains (102.4 Mm × 102.4 Mm × 50.6 Mm) placed at latitudes of 0 ° (equator), 30 ° , and 60 ° , using the f -plane approximation. Because the star has a relatively shallow convection zone (28.5 Mm thick or about 3% R * ), we model its dynamics from the upper layers of the radiative zone, the whole convection zone, and the low atmosphere. The initial simulation results indicate that rotation suppresses temperature and density perturbations in the upper convection zone, leading to a decrease in the mean temperature throughout the convection zone. In addition to the multiscale granular-type convection, the simulations reveal the formation of roll-like patterns, the circulation in which is responsible for the retrograde flows extending from the photosphere to the bottom of the convection zone, where the mean flows transition to prograde motions with the onset of solid body rotation in the radiative zone, forming the tachocline in the overshooting layer. In this paper, we primarily discuss the properties of the outer convection zone for different rotation rates. A detailed analysis of the properties of the tachocline, the overshoot layer, as well as the properties of acoustic and gravity waves, will be discussed in follow-up papers.}, archive = {J_ApJ}, author = {Irina N. Kitiashvili and Alexander G. Kosovichev and Alan A. Wray}, doi = {10.3847/1538-4357/adfbe4}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {187}, shortjournal = {The Astrophys. J.}, title = {Properties of turbulent convection and large-scale flows in a rotating F-type star revealed by 3D realistic radiative hydrodynamic simulations}, volume = {991}, year = {2025}, }
• (2025). Magneto-thermal coupling and coronal heating in solar active regions inferred from microwave observations. ApJ, 991(2), 186. (www)

  @article{ , abstract = {The solar corona is much hotter than the photosphere and chromosphere, but the physical mechanism responsible for heating the coronal plasma remains unidentified. The thermal microwave emission, which is produced in a strong magnetic field above sunspots, is a promising but barely exploited tool for studying the coronal magnetic field and plasma. We analyzed the microwave observations of eight solar active regions obtained with the Siberian Radioheliograph in the years 2022–2024 in the frequency range of 6–12 GHz. We produced synthetic microwave images based on various coronal heating models, and determined the model parameters that provided the best agreement with the observations. The observations and simulations strongly favor either a steady-state (continuous) plasma heating process or high-frequency heating by small energy release events with a short cadence. The average magnetic field strength in a coronal loop was found to decrease with the loop length, following a scaling law with the most probable index of about −0.55. In the majority of cases, the estimated volumetric heating rate was weakly dependent on the magnetic field strength and decreased with the coronal loop length following a scaling law with an index of about −2.5. Among the known theoretical heating mechanisms, the model based on wave transmission or reflection in coronal loops acting as resonance cavities was found to provide the best agreement with the observations. The obtained results did not demonstrate a significant dependence on the emission frequency in the considered range.}, archive = {J_ApJ}, author = {Alexey A. Kuznetsov and Gregory D. Fleishman and Gelu M. Nita and Sergey A. Anfinogentov}, doi = {10.3847/1538-4357/adfc4b}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {186}, shortjournal = {The Astrophys. J.}, title = {Magneto-thermal coupling and coronal heating in solar active regions inferred from microwave observations}, volume = {991}, year = {2025}, }
• (2025). C3PO. v. comoving pairs indicate rotational spin-down drives the main-sequence li-dip. ApJ, 991(2), 185. (www)

  @article{ , abstract = {The lithium-dip observed in mid-F dwarfs remains a long-standing challenge for stellar evolution models. We present high-precision stellar parameters and A (Li) for 22 new comoving pairs, primarily located on the hotter side of the Li-Dip. Combined with pairs from the C3PO catalog, our sample includes 124 stars with T eff between 6000 and 7300 K, encompassing and extending slightly beyond the Li-Dip. Among them, 49 comoving pairs (98 stars) have both components within the temperature range of interest. Using this expanded set of comoving pairs observed with high-resolution spectroscopy, we show that rotational spin down is the dominant process responsible for Li depletion in the Li-Dip. First, within comoving pairs, the star with v sin i > 12 km s −1 shows higher A (Li) than its more slowly rotating companion within the Li-Dip, indicating that rotation-dependent mixing drives lithium depletion. Second, we observe a correlation between A (Li) and v sin i : fast rotators retain higher A (Li) with less scatter, while slow rotators show lower A (Li) and greater dispersion. Third, among slow rotators, A (Li) varies widely, suggesting that differences in initial rotation rates and spin-down histories influence how much Li is depleted. Some stars may have formed as fast rotators and spun down rapidly, leading to more Li depletion, while others may have started as slow rotators and retained more of their initial Li. These results demonstrate that rotational induced mixing plays an important role in shaping the Li-Dip beyond the effects of stellar age and mass.}, archive = {J_ApJ}, author = {Qinghui Sun and Yuan-Sen Ting and Barbara J. Anthony-Twarog and Bruce A. Twarog and Fan Liu and Yuxi(Lucy) Lu}, doi = {10.3847/1538-4357/adfccd}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {185}, shortjournal = {The Astrophys. J.}, title = {C3PO. v. comoving pairs indicate rotational spin-down drives the main-sequence li-dip}, volume = {991}, year = {2025}, }
• (2025). The kinematical behavior of solar eruptive filaments affected by the poloidal magnetic field. ApJ, 991(2), 184. (www)

  @article{ , abstract = {Kinematics of solar eruptive filaments is one of the important diagnostic parameters for predicting whether solar eruptions would induce geomagnetic storms. Particularly, some geomagnetic storms might be induced by solar filament eruptions originating from unexpected surface source regions because of nonradial ejection. The nonradial ejection of filaments has received widespread attention but remains inconclusive. We select two eruptive filaments, both of which are supported by flux ropes, as indicated by the hot channel structures seen in the 94 Å images and the hook-shaped brightenings where the filament material falls back. We measure the three-dimensional ejection trajectory of the eruptive filaments by integrating the simultaneous observations from the Solar Dynamics Observatory (SDO) and Solar Terrestrial Relations Observatory (STEREO). Furthermore, we calculate the distribution of the poloidal field along the ejection path and compare it to the ejection acceleration. It is revealed that the reinforcement of the poloidal magnetic field may lead to the suppression of the acceleration, with the acceleration resuming its increase only when the poloidal field diminishes to a certain level. Additionally, we compute the spatial distribution of the poloidal field in various directions and find that the poloidal magnetic field above the filaments is asymmetric. For both investigated events, the filaments appear to eject toward the side where the poloidal magnetic field is weaker, indicating that the eruptive filaments tend to propagate along the side with weaker strapping force. This may provide a new explanation for the inclined ejection of filaments.}, archive = {J_ApJ}, author = {Ye Qiu and Yang Guo and Mingde Ding and Chuan Li and Linggao Kong and Zhen Li}, doi = {10.3847/1538-4357/adfd54}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {184}, shortjournal = {The Astrophys. J.}, title = {The kinematical behavior of solar eruptive filaments affected by the poloidal magnetic field}, volume = {991}, year = {2025}, }
• (2025). Active galactic nuclei in the extremely overdense galaxy region BOSS 1441: A chandra observation. ApJ, 991(2), 183. (www)

  @article{ , abstract = {We present a Chandra/ACIS-I study of X-ray sources in BOSS 1441, a protocluster at z = 2.32 ± 0.02 that exhibits a prominent overdensity of Ly α emitters (LAEs). Using a 45 ks observation, we identify seven X-ray sources spatially coincident with LAE density peaks. The average X-ray photon index for the seven sources, derived from an absorbed power-law model with Galactic absorption fixed, is 1.49 (ranging from −0.68 to 2.51), corresponding to an average luminosity of 6.85 × 10 44 erg s −1 in the rest-frame 2–33 keV band, with individual luminosities spanning (3.57–13.96) × 10 44 erg s −1 . Three sources exhibit relatively flat spectral slopes. Two are associated with the MAMMOTH-1 nebula, while the third, located at the edge of BOSS 1441 with a \gt 5\,^{\prime} \, offset from the LAE density peak, resides in a region with a high submillimeter-band density. We estimate the fraction of X-ray-detected active galactic nuclei (AGNs) among the LAEs to be 11.{5}_{-4.6}^{+3.8} \% , approximately double that of previously studied LAEs. This elevated fraction suggests BOSS 1441 is in a mature evolutionary stage, with even higher AGN fractions expected in massive LAEs such as PKS 1138-262. In contrast, the submillimeter galaxy population shows a lower AGN fraction ( 6.{9}_{-4.5}^{+6.9} \% ), consistent with their typically obscured nature. These results indicate that the protocluster’s massive galaxies are evolving into the bright red sequence galaxies observed in local clusters, where AGNs likely play a critical role in quenching their star formation.}, archive = {J_ApJ}, author = {Jiahua Wu and Liming Dou and Zheng Cai and Yanli Ai and Shiwu Zhang and Zhenya Zheng and Xiaohui Fan and Yuanyuan Su and Jianfeng Wu}, doi = {10.3847/1538-4357/adff7c}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {183}, shortjournal = {The Astrophys. J.}, title = {Active galactic nuclei in the extremely overdense galaxy region BOSS 1441: A chandra observation}, volume = {991}, year = {2025}, }
• (2025). The close binary properties of massive stars across different environments within the LMC. ApJ, 991(2), 182. (www)

  @article{ , abstract = {We analyze 4859 O stars in the third phase of the Optical Gravitational Lensing Experiment photometric survey of the LMC, including 415 eclipsing binaries (EBs). After accounting for the geometrical probability of eclipses, the period distribution of O-type binaries across P = 2.5–200 days follows a power law f log P ∝ (log P ) Π with Π = −0.34 ± 0.06, which is skewed toward shorter periods compared to Opik’s law (Π = 0). We divide our O stars into seven environments based on their clustering with B stars and other O stars. The EB fraction of O stars in young clusters is 10.2% ± 0.6%, which matches the 10.8% ± 2.1% for O stars in young Milky Way clusters. O stars in old clusters exhibit a lower EB fraction of 5.5% ± 0.9% due to the effects of binary evolution. O stars in young dense clusters, young sparse associations, and even low-mass clusters that formed in situ in the field have similar EB fractions. This uniformity suggests that the formation of close massive binaries depends on small-scale gas physics, e.g., fragmentation and migration within protostellar disks, whereas N -body interactions that scale with cluster density do not affect the close binary properties of massive stars that remain in clusters. Conversely, ejected O stars in the field exhibit a lower close binary fraction. The EB fractions of field walkaways (projected velocities v proj < 24.5 km s −1 ) and field runaways ( v proj > 24.5 km s −1 ) are 7.3% ± 1.0% and 4.7% ± 1.0%, respectively. These values suggest that most field O stars were dynamically ejected via N -body interactions from their birth clusters, whereas field O stars that formed in situ or were kicked from supernova explosions in binaries contribute 17% and <28%, respectively, to the field population.}, archive = {J_ApJ}, author = {Maxwell Moe and M. S. Oey and Irene Vargas-Salazar and Kaitlin M. Kratter}, doi = {10.3847/1538-4357/ae0034}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {182}, shortjournal = {The Astrophys. J.}, title = {The close binary properties of massive stars across different environments within the LMC}, volume = {991}, year = {2025}, }
• (2025). Observations of the fluctuations in the interplanetary magnetic field around l1 point during the solar transient events of 2024 with MAG payload on board aditya-l1 spacecraft. ApJ, 991(2), 181. (www)

  @article{ , abstract = {The magnetometer (MAG) payload on board India’s first solar mission, Aditya-L1, is a dual-sensor fluxgate magnetometer designed to measure the interplanetary magnetic field (IMF) while operating in a halo orbit around the first Sun–Earth Lagrangian point (L1). Since becoming operational in 2024 January, MAG has continuously recorded local magnetic field data and has captured several solar transient events over the past 1 yr. During these events, the IMF, typically around 5 nT, exhibited significant enhancements in magnitude. This study focuses on three such solar events observed in 2024 March, May, and October. Analysis of the magnetic field power spectra during these events reveals fluctuations consistent with Kolmogorov-type turbulence, characterized by a spectral slope close to −5/3. To emphasize changes in spectral behavior, the event-day spectra are compared with those from a day when the quiet solar wind conditions prevail. A marked contrast is observed: while the quiet periods exhibit anisotropic turbulence, the extreme events display quasi-isotropic behavior, with spectral slopes closely following the Kolmogorov spectrum across all three IMF components. The results, including detailed variations in spectral slope and turbulence characteristics, are presented and discussed in this paper.}, archive = {J_ApJ}, author = {Vipin K. Yadav and R.K. Choudhary and M. Midhun Goutham}, doi = {10.3847/1538-4357/ae00b6}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {181}, shortjournal = {The Astrophys. J.}, title = {Observations of the fluctuations in the interplanetary magnetic field around l1 point during the solar transient events of 2024 with MAG payload on board aditya-l1 spacecraft}, volume = {991}, year = {2025}, }
• (2025). The spectra of a radiative reprocessing outflow model for fast blue optical transients. ApJ, 991(2), 180. (www)

  @article{ , abstract = {The radiation reprocessing model, in which an optically thick outflow absorbs the high-energy emission from a central source and reemits in longer wavelengths, has been frequently invoked to explain some optically bright transients, such as fast blue optical transients (FBOTs), whose progenitor and explosion mechanism are still unknown. Previous studies on this model did not take into account the frequency dependence of the opacity. We study the radiative reprocessing and calculate the UV-optical-near-infrared (NIR) band spectra from a spherical outflow composed of pure hydrogen gas, for a time-dependent outflowing mass rate. Electron scattering and frequency-dependent bound–free and free–free opacities are considered. The spectrum deviates from the blackbody at NIR and UV frequencies; in particular, it has νL ν ∝ ν 1.5 at NIR frequencies, because at these frequencies the absorption optical depth from the outflow’s outer edge to the so-called photon trapping radius is large and is frequency dependent. We apply our model to the prototype FBOT AT2018cow by fitting the spectra to the observed spectral energy distribution. The best-fit mass-loss rate suggests that the total outflow mass in AT2018cow is {M}_{{\rm{out}}}\approx 5.{7}_{-0.4}^{+0.4}\,{M}_{\odot } . If that equals the total mass lost during an explosion, and if the progenitor is a blue supergiant (with a preexplosion mass of ∼20 M ⊙ ), then it will suggest that the central compact remnant mass is at least ≈14 M ⊙ . This would imply that the central remnant is a black hole.}, archive = {J_ApJ}, author = {Chun Chen and Rong-Feng Shen}, doi = {10.3847/1538-4357/ae0181}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {180}, shortjournal = {The Astrophys. J.}, title = {The spectra of a radiative reprocessing outflow model for fast blue optical transients}, volume = {991}, year = {2025}, }
• (2025). The rise of the galactic empire: Ultraviolet luminosity functions at z ∼ 17 and z ∼ 25 estimated with the MIDIS+NGDEEP ultra-deep JWST/NIRCam data set. ApJ, 991(2), 179. (www)

  @article{ , abstract = {We present a sample of six F200W and three F277W dropout sources identified as 16 < z < 25 galaxy candidates using the deepest JWST/NIRCam data to date (5 σ depths ∼31.5 mag at ≥2 μ m), provided by the MIRI Deep Imaging Survey and the Next Generation Deep Extragalactic Exploratory Public survey. We estimate ultraviolet (UV) luminosity functions and densities at z ∼ 17 and z ∼ 25. The number density of galaxies with absolute magnitudes of −19 < M UV < −18 at z ∼ 17 ( z ∼ 25) is a factor of 4 (25) smaller than at z ∼ 12; the luminosity density presents a similar evolution. Compared to state-of-the-art galaxy simulations, we find the need for an enhanced UV-photon production at z = 17–25 in M DM = 10 8.5−9.5 M ⊙ dark matter halos, provided by an increase in the star formation efficiency at early times and/or by intense compact starbursts with enhanced emissivity linked to strong burstiness, low or primordial gas metallicities, and/or a top-heavy initial mass function. There are a few robust theoretical predictions for the evolution of galaxies above z ∼ 20 in the literature; however, the continuing rapid drop in the halo mass function would predict a more rapid evolution than we observe if photon production efficiencies remained constant. Our z > 16 candidates present mass-weighted ages around 30 Myr, and attenuations A ( V ) < 0.1 mag. Their average stellar mass is M ⋆ ∼ 10 7 M ⊙ , implying a stellar-to-baryon mass fraction around 10% if the emissivity increases with redshift, or significantly higher otherwise. Three candidates present very blue UV spectral slopes ( β ∼ −3) compatible with Population III young (≲10 Myr) stars and/or high escape fractions of ionizing photons; the rest have β ∼ −2.5 similar to the z = 10–12 samples.}, archive = {J_ApJ}, author = {Pablo G. Pérez-González and Göran Östlin and Luca Costantin and Jens Melinder and Steven L. Finkelstein and Rachel S. Somerville and Marianna Annunziatella and Javier Álvarez-Márquez and Luis Colina and Avishai Dekel and Henry C. Ferguson and Zhaozhou Li and L. Y. Aaron Yung and Micaela B. Bagley and Leindert A. Boogaard and Denis Burgarella and Antonello Calabrò and Karina I. Caputi and Yingjie Cheng and Mark Dickinson and Andreas Eckart and Mauro Giavalisco and Steven Gillman and Thomas R. Greve and Mahmoud Hamed and Nimish P. Hathi and Jens Hjorth and Marc Huertas-Company and Jeyhan S. Kartaltepe and Anton M. Koekemoer and Vasily Kokorev and Álvaro Labiano and Danial Langeroodi and Gene C. K. Leung and Priyamvada Natarajan and Casey Papovich and Florian Peissker and Laura Pentericci and Nor Pirzkal and Pierluigi Rinaldi and Paul van der Werf and Fabian Walter}, doi = {10.3847/1538-4357/adf8c9}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {179}, shortjournal = {The Astrophys. J.}, title = {The rise of the galactic empire: Ultraviolet luminosity functions at z ∼ 17 and z ∼ 25 estimated with the MIDIS+NGDEEP ultra-deep JWST/NIRCam data set}, volume = {991}, year = {2025}, }
• (2025). Pair cascades in magnetar magnetospheres. ApJ, 991(2), 178. (www)

  @article{ , abstract = {Resonant inverse Compton scattering (RICS) of soft thermal photons by relativistic particles on closed magnetic field loops has been proposed to explain the hard emission observed up to and beyond 200 keV from magnetars. If particles injected at the base of the loops have Lorentz factors ≳10 2 , the RICS spectra will be attenuated by both one-photon pair production and photon splitting in the ultrastrong magnetar fields, producing additional spectral components from pair synchrotron radiation and split photons that produce further generations of pairs and split photons. We investigate such cascades initiated by the primary injected electrons through a Monte Carlo simulation, and study the cascade spectra and pair distributions. For most observer angles, the pair synchrotron and split-photon spectra dominate the RICS primary spectra and produce complex polarization signals. In particular, the synchrotron spectra are highly polarized with degree 40%–80%, are softer than the RICS spectra, and may account for the high polarization of some magnetar spectra observed by the Imaging X-ray Polarimetry Explorer above 3 keV.}, archive = {J_ApJ}, author = {Alice K. Harding and Zorawar Wadiasingh and Matthew G. Baring}, doi = {10.3847/1538-4357/adfa06}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {178}, shortjournal = {The Astrophys. J.}, title = {Pair cascades in magnetar magnetospheres}, volume = {991}, year = {2025}, }
• (2025). Illuminating hidden pulsars: Scintillation-enhanced discovery of two binary millisecond pulsars in m13 with FAST. ApJ, 991(2), 177. (www)

  @article{ , abstract = {We conducted a sensitive acceleration search using fast Fourier transform techniques on full-length and segmented data from 84 observations of the globular cluster M13 with the Five-hundred-meter Aperture Spherical radio Telescope. Employing a low detection threshold (2 σ ) to maximize sensitivity to faint pulsars, here we report the discovery of two binary millisecond pulsars: J1641+3627G (M13G) and J1641+3627H (M13H). Both pulsars were detected during scintillation-brightened states, revealing systems that would otherwise remain undetected. For M13G, we obtained a phase-connected timing solution spanning 6.4 yr, identifying it as a black widow system with an orbital period of 0.12 days hosting an extremely low-mass companion (∼9.9 × 10 −3 M ⊙ ), though no eclipses were observed. M13H, however, shows significant apparent acceleration but was detected in only 2 of 84 observations; its extremely low detection rate currently prevents constraints on orbital parameters or classification.}, archive = {J_ApJ}, author = {Dejiang Yin and Lin Wang and Li-yun Zhang and Lei Qian and Baoda Li and Kuo Liu and Bo Peng and Yinfeng Dai and Yaowei Li and Zhichen Pan}, doi = {10.3847/1538-4357/adfa14}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {177}, shortjournal = {The Astrophys. J.}, title = {Illuminating hidden pulsars: Scintillation-enhanced discovery of two binary millisecond pulsars in m13 with FAST}, volume = {991}, year = {2025}, }
• (2025). Radiative transfer modeling of a shadowed protoplanetary disk assisted by a neural network. ApJ, 991(2), 176. (www)

  @article{ , abstract = {We present observations and detailed modeling of a protoplanetary disk around the T Tauri star V1098 Sco. Millimeter-wavelength data from the Atacama Large Millimeter/submillimeter Array (ALMA) show a ring of large dust grains with a central cavity that is filled with molecular gas. Near-infrared data from the Very Large Telescope (VLT) detect the scattered starlight from the disk surface and reveal a large shadow that extends over its entire southern half. We model the ALMA continuum and line data to determine the outer-disk geometry and the central stellar mass. Using radiative transfer models, we demonstrate that a misaligned inner disk, tilted in both inclination and position angle with respect to the outer disk, can reproduce the salient scattered-light features seen with VLT. Applying an image threshold algorithm to compare disk morphologies and training a neural network on a set of high-signal-to-noise-ratio models, we forward model the data and determine the inner-disk geometry. We find that the rotation axes of the inner and outer disks are misaligned by 38° and constrain the mass and location of a perturbing planetary or substellar companion. The technique of simulation-based inference that is illustrated here is broadly applicable for radiative transfer modeling of other objects.}, archive = {J_ApJ}, author = {Jonathan P. Williams and Myriam Benisty and Christian Ginski and Giuseppe Lodato and Maria Vincent}, doi = {10.3847/1538-4357/adfa15}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {176}, shortjournal = {The Astrophys. J.}, title = {Radiative transfer modeling of a shadowed protoplanetary disk assisted by a neural network}, volume = {991}, year = {2025}, }
• (2025). The arizona molecular ISM survey with the SMT: The diverse carbon monoxide line ratios and spectral line energy distributions of star-forming galaxies. ApJ, 991(2), 175. (www)

  @article{ , abstract = {The carbon monoxide (CO) spectral line energy distributions (SLEDs) of galaxies contain a wealth of information about conditions in their cold interstellar gas. Here, we use galaxy-scale observations of the three lowest energy CO lines to determine SLEDs and line ratios in a sample of 47 nearby, predominantly star-forming galaxies. We find a systematic trend of higher gas excitation with increasing star formation rate (SFR) and SFR surface density (Σ SFR ), with the range of variations being even larger than predicted by simulations. Power-law fits of the CO line ratios as a function of SFR and Σ SFR provide a good description of the trends seen in our sample and also accurately predict values for a wide range of galaxy types compiled from the literature. Based on these fits, we provide prescriptions for estimating CO(1–0) luminosities and molecular gas masses using CO(3–2) or CO(2–1) in cases where CO(1–0) is not observed directly. We compare our observed SLEDs with molecular cloud models in order to examine how the physical properties of cold gas vary across the galaxy population. We find that gas conditions in star-forming and starburst galaxies lie on a continuum with increasing gas density in more actively star-forming systems.}, archive = {J_ApJ}, author = {Ryan P. Keenan and Daniel P. Marrone and Garrett K. Keating}, doi = {10.3847/1538-4357/adf554}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {175}, shortjournal = {The Astrophys. J.}, title = {The arizona molecular ISM survey with the SMT: The diverse carbon monoxide line ratios and spectral line energy distributions of star-forming galaxies}, volume = {991}, year = {2025}, }
• (2025). Challenging classical paradigms: Recurrent nova M31N 2017-01e, a BeWD system in m31?. ApJ, 991(2), 174. (www)

  @article{ , abstract = {M31N 2017-01e is the second-fastest recurrent nova known, with a recurrence period of 2.5 yr in the Andromeda galaxy (M31). This system exhibits a unique combination of properties: a low outburst amplitude (∼3 mag), starkly contrasting with known recurrent novae (typically ≥6 mag), and a very fast evolution ( t 2 ∼ 5 days). Its position coincides with a bright variable source ( M V ∼ −4.2, B − V = 0.042) displaying a 14.3 day photometric modulation, which has been suggested as the likely progenitor. We present a multiwavelength analysis of optical and UV data spanning quiescence and the 2019 and 2024 outbursts. Archival high-resolution imaging reveals two nearby faint sources within 5″ of the proposed nova system, which we identified as unrelated field stars. Color analysis and spectral energy distribution fitting suggest the progenitor is likely an early-type star. Combined with archival spectra consistent with a B-type star with H α in emission, this points to the quiescent counterpart being a Be star with a circumstellar disk. We propose that M31N 2017-01e arises from a rare BeWD binary , where the white dwarf (WD) accretes from the decretion disk of its companion, explaining its rapid recurrence, low-amplitude outbursts, and unusual quiescent luminosity and color. This analysis highlights M31N 2017-01e as a compelling outlier among recurrent novae, suggesting a distinct accretion mechanism and evolutionary path that challenges the prevailing paradigm.}, archive = {J_ApJ}, author = {Shatakshi Chamoli and Judhajeet Basu and Sudhanshu Barway and G.C. Anupama and Vishwajeet Swain and Varun Bhalerao}, doi = {10.3847/1538-4357/adf843}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {174}, shortjournal = {The Astrophys. J.}, title = {Challenging classical paradigms: Recurrent nova M31N 2017-01e, a BeWD system in m31?}, volume = {991}, year = {2025}, }
• (2025). A spectroscopic hunt for Post–Red supergiants in the large magellanic cloud. II. turbulent line broadening in the spectra of LMC yellow supergiants. ApJ, 991(2), 173. (www)

  @article{ , abstract = {Massive stars in the Hertzsprung gap are a mixed population of objects in short-lived evolutionary phases: yellow supergiants (YSGs) evolving toward the red supergiant (RSG) phase, partially stripped post-RSGs, and other, rarer outcomes of stellar evolution. Studies of sufficiently large samples of these objects can constrain massive star structure and evolution during these poorly understood phases. As part of our ongoing program searching for post-RSGs, we characterized the spectral line profiles of 32 YSGs in the Large Magellanic Cloud using high-resolution spectra obtained with the Magellan Inamori Kyocera Echelle spectrograph on the Magellan 2/Clay telescope at Las Campanas Observatory. We find that the line profiles are strongly broadened by turbulent photospheric motion. After fitting the profiles to measure microturbulent and macroturbulent velocities, we identify two groups within our sample that are separated by the ratio of the two velocity scales. In both groups, the macroturbulent velocity ζ RT scales with stellar properties such as effective temperature. Additionally, we find statistically significant correlations between the macroturbulent velocity and other possible probes of large-scale photospheric motions: line profile asymmetry, as well as the amplitude and quality factor of the stochastic low frequency variability measured from Transiting Exoplanet Survey Satellite lightcurves. These correlations differ between the two groups of YSGs. Finally, we construct 1D evolutionary models of YSGs in both pre- and post-RSG phases, and find reasonable agreement between the convective velocities in these models and our measured microturbulent velocities. However, the macroturbulent velocities are much higher than the convective velocities in the models.}, archive = {J_ApJ}, author = {Trevor Z. Dorn-Wallenstein and Kaitlyn M. Chen and Samantha C. Wu and Jared A. Goldberg and Anna J. G. O’Grady and Ayanna T. Mann and Poderosa I. Don-Wallanchez}, doi = {10.3847/1538-4357/adfa8f}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {173}, shortjournal = {The Astrophys. J.}, title = {A spectroscopic hunt for Post–Red supergiants in the large magellanic cloud. II. turbulent line broadening in the spectra of LMC yellow supergiants}, volume = {991}, year = {2025}, }
• (2025). Stellar obliquity excitation via disk-dispersal-driven resonances in binaries. ApJ, 991(2), 172. (www)

  @article{ , abstract = {The stellar obliquity of a planetary system is often used to help constrain the system’s formation and evolution. One of the mechanisms to reorient the stellar spin involves a secular resonance crossing due to the dissipation of the protoplanetary disk when the system also has an inclined, distant (∼300 au) binary companion. This mechanism is likely to operate broadly due to the ∼50% binary fraction of FGK dwarfs and can play an important role in setting the initial stellar obliquities prior to any dynamical evolution. In this work, we revisit this mechanism analytically for idealized, homologously evolving disk models and show that the resulting stellar obliquities are broadly distributed between 60° and 180° for most warm and cold planets. We further show that nonhomologous disk dissipation, such as the development of a photoevaporatively opened gap at ∼2 au, can help maintain the orbital alignment of warm planets, in agreement with observations. Our results represent the proper primordial obliquities for planetary systems with distant binary companions. They also represent the obliquities of stars with no present-day binary companions if these companions are dynamically unbound during the birth cluster phase of evolution, a process that occurs on a comparable timescale as the disk-driven obliquity excitation.}, archive = {J_ApJ}, author = {Yubo Su and Dong Lai}, doi = {10.3847/1538-4357/adfcbf}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {172}, shortjournal = {The Astrophys. J.}, title = {Stellar obliquity excitation via disk-dispersal-driven resonances in binaries}, volume = {991}, year = {2025}, }
• (2025). Abundance diagnostics from a slitless imaging spectrometer: A proof-of-concept for MaGIXS-2. ApJ, 991(2), 171. (www)

  @article{ , abstract = {Elemental abundance diagnostics in the solar corona are crucial for understanding energy transport, plasma heating, and magnetic activity. Most earlier imaging-spectroscopic studies have relied on slit-based spectrometers, which offer high spectral resolution but are limited in spatiotemporal coverage and temperature diagnostics. In contrast, slitless spectrographs like the Marshall Grazing Incidence X-ray Spectrometer (MaGIXS) produce overlapping spatial-spectral data (overlappograms) to enable wide-field imaging spectroscopy with broader temperature coverage. However, extracting elemental abundances from overlappogram data remains inherently challenging due to spatial and spectral confusion. In this work, we present a proof-of-concept technique for elemental abundance diagnostics from overlappograms, demonstrating its feasibility with simulated MaGIXS-2 observations.}, archive = {J_ApJ}, author = {Biswajit Mondal and Amy R. Winebarger and P. S. Athiray}, doi = {10.3847/1538-4357/adfe6e}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {171}, shortjournal = {The Astrophys. J.}, title = {Abundance diagnostics from a slitless imaging spectrometer: A proof-of-concept for MaGIXS-2}, volume = {991}, year = {2025}, }
• (2025). Tracing the origins of hot halo gas in milky way–type galaxies with SMUGGLE. ApJ, 991(2), 170. (www)

  @article{ , abstract = {Current galaxy formation models predict the existence of X-ray-emitting gaseous halos around Milky Way (MW)–type galaxies. To investigate properties of this coronal gas in MW-like galaxies, we analyze a suite of high-resolution simulations based on the SMUGGLE framework and compare the results with X-ray observations of both the MW and external galaxies. We find that for subgrid models incorporating any form of stellar feedback, e.g., early feedback (including stellar winds and radiation) and/or supernova (SN) explosions, the total 0.5–2 keV luminosity is consistent within uncertainties with X-ray observations of the MW and with scaling relations derived for external disk galaxies. However, all models exhibit an X-ray surface brightness profile that declines too steeply beyond ∼5 kpc, underpredicting the extended emission seen in recent eROSITA stacking results. Across all subgrid prescriptions, the simulated surface brightness and emission measure fall below MW observations by at least 1–2 orders of magnitude, with the most severe discrepancy occurring in the no-feedback model. Our results suggest that (i) stellar feedback primarily shapes the innermost hot atmosphere (central ∼5 kpc), with comparable contributions from early feedback and SNe to the resulting X-ray luminosity; (ii) additional mechanisms such as gravitational heating, active galactic nuclei feedback, and/or Compton effects of GeV cosmic ray are necessary to generate the extended, volume-filling hot gaseous halo of MW-mass galaxies; (iii) the origins of hot corona in MW-like galaxies are partially distinct from those of the warm (∼10 5 K) gas, by combining our previous finding that the SMUGGLE model successfully reproduces the kinematics and spatial distribution of MW O vi absorbers.}, archive = {J_ApJ}, author = {Zhijie Zhang and Xiaoxia Zhang and Hui Li and Taotao Fang and Yang Luo and Federico Marinacci and Laura V. Sales and Paul Torrey and Mark Vogelsberger and Qingzheng Yu and Feng Yuan}, doi = {10.3847/1538-4357/ae019f}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {170}, shortjournal = {The Astrophys. J.}, title = {Tracing the origins of hot halo gas in milky way–type galaxies with SMUGGLE}, volume = {991}, year = {2025}, }
• (2025). Pioneering high-speed pulsar parameter estimation using convolutional neural networks. ApJ, 991(2), 169. (www)

  @article{ , abstract = {Accurate thermal emission models of neutron stars are essential for constraining the dense matter equation of state. However, incorporating realistic magnetic field structures is computationally prohibitive, severely constraining feasible parameter space exploration. In this work, we develop a neural network (NN) emulator to generate model thermal bolometric X-ray light curves of millisecond pulsars with multipolar magnetic fields. We assess the NN’s predictive and computational performance across a broad parameter space. We find that for a static vacuum field model, the NN provides a >400 times speedup. We integrate this NN emulator into a Monte Carlo Markov Chain (MCMC) framework to replace the computationally expensive physical model during parameter exploration. Applied to PSR J0030+0451, this approach allows the MCMC to reach equilibrium in ∼1 day on 4000 cores, where with the original physical model alone it would have taken more than a year on the same hardware. We compare posterior distributions by running equivalent MCMC iterations with both the NN and the physical model, evaluate differences in distributions when continuing the physical model MCMC from the NN MCMC equilibrium state, and assess variations in posterior distributions resulting from NNs trained on data sets of different sizes. Our NN architecture is agnostic to the underlying physics of the physical model and can be trained for any other physical model, opening many previously intractable avenues of analysis. The NN speed remains the same regardless of the complexity of the physical model it was trained to emulate, allowing greater speedups for more complex physical models.}, archive = {J_ApJ}, author = {Greg Olmschenk and Emily Broadbent and Constantinos Kalapotharakos and Wendy F. Wallace and Thibault Lechien and Zorawar Wadiasingh and Demosthenes Kazanas and Alice Harding}, doi = {10.3847/1538-4357/ae03c0}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {169}, shortjournal = {The Astrophys. J.}, title = {Pioneering high-speed pulsar parameter estimation using convolutional neural networks}, volume = {991}, year = {2025}, }
• (2025). Gravitational influence from planets on the measured rates of period change of pulsating white dwarfs. ApJ, 991(2), 168. (www)

  @article{ , abstract = {The measured rates of period change, \dot{P} , in the signals of pulsating white dwarf stars are often interpreted as direct detections of structural changes from secular cooling. Due to the intrinsic nature of this quantity, \dot{P} analysis has been used to probe fundamental physics, such as constraining the mass of hypothetical axion particles. However, most white dwarfs are expected to host planets that could induce an external source of period change, caused by the light travel time variations from reflex motion about the system barycenter. Assuming a plausible distribution of planets that could orbit white dwarf stars, we quantify the amount of reflex motion expected from undiscovered planets as an important source of extrinsic error in \dot{P} analyses. While the median error from reflex motion is ∼10 −15 s s −1 (similar to the secular \dot{P} rates expected for cool DAV pulsators), individual close-in planets could cause \dot{P} errors as large as 10 −11 s s −1 .}, archive = {J_ApJ}, author = {Ling Xuan Yao and Keaton J. Bell and Andrew Dublin}, doi = {10.3847/1538-4357/adfb66}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {168}, shortjournal = {The Astrophys. J.}, title = {Gravitational influence from planets on the measured rates of period change of pulsating white dwarfs}, volume = {991}, year = {2025}, }
• (2025). Variabilities driven by satellite black hole migration in active galactic nucleus disks. ApJ, 991(2), 167. (www)

  @article{ , abstract = {The physical origin of active galactic nucleus (AGN) variability remains unclear. Here we propose that the magnetic reconnection induced by the migration of satellite black holes (sBHs) in the AGN disk can be a new plausible mechanism for AGN short-term variability. During the sBH migration, the comoving plasmas surrounding the sBH could influence the large-scale magnetic field of the AGN disk and trigger the magnetic reconnections to contribute to AGN UV/optical variability. Meanwhile, high-magnetization plasmas are more likely to escape the disk and cause a secondary magnetic reconnection in the corona. For a ∼10 2 –10 3 M ⊙ sBH in the inner regions of the disk surrounding a supermassive black hole with ∼10 7 M ⊙ , the reconnection process that occurred in the space outside of the disk should produce X-ray emission, which can last ∼10 3 –10 6 s with the luminosity ∼10 38 –10 42 erg s −1 .}, archive = {J_ApJ}, author = {Jing-Tong Xing and Tong Liu and Bao-Quan Huang and Mouyuan Sun}, doi = {10.3847/1538-4357/adff71}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {167}, shortjournal = {The Astrophys. J.}, title = {Variabilities driven by satellite black hole migration in active galactic nucleus disks}, volume = {991}, year = {2025}, }
• (2025). Global hot gas excess in (Ultra)Luminous infrared galaxies: Replicating galactic nuclei scaling relations between diffuse X-ray emission and star formation on galaxy-wide scales. ApJ, 991(2), 166. (www)

  @article{ , abstract = {Hot ionized interstellar medium interlinks star formation and stellar feedback processes, redistributing energy, momentum, and material throughout galaxies. We use X-ray data from Chandra to extract the hot gas emission from 78 of the most luminous infrared-selected galaxies in the local Universe. In the extreme star-forming environments, the intrinsic thermal X-ray luminosity of hot gas ( {L}_{0.5-2\,{\rm{keV}}}^{{\rm{gas}}} ) shows a significant excess over the predictions of the standard linear L X −SFR relation for most objects with very high star formation rates (SFRs). The contribution of active galactic nuclei appears to have little impact on the global hot gas luminosity. For galaxies with SFR > 50 M ⊙ yr −1 , the Bayesian analysis gives a superlinear relation of {\rm{log}}({L}_{0.5-2\,{\rm{keV}}}^{{\rm{gas}}}/{\rm{erg}}\,{{\rm{s}}}^{-1})=1.34\,{\rm{log}}({\rm{SFR}}/{M}_{\odot }\,{{\rm{yr}}}^{-1})+39.82 , similar to that found in the central regions of normal spiral galaxies. These results suggest a scenario in which the merger of galaxies delivers substantial amounts of gas, triggering intense star formation in both the nuclear region and the galactic disk, and ultimately enhancing the global thermal X-ray emission. The ratio of the apparent thermal luminosity in the 0.5−2 keV band ( {L}_{0.5-2\,{\rm{keV}}}^{{\rm{appar}}} ) to {L}_{0.5-2\,{\rm{keV}}}^{{\rm{gas}}} shows statistically significant negative correlations with the intrinsic column density ( N H ) and SFR. Moreover, in contrast to the luminosity ratio, SFR shows a moderate positive correlation with intrinsic N H . This suggests that the correlation between {L}_{0.5-2\,{\rm{keV}}}^{{\rm{appar}}} / {L}_{0.5-2\,{\rm{keV}}}^{{\rm{gas}}} and SFR may be driven by the underlying {L}_{0.5-2\,{\rm{keV}}}^{{\rm{appar}}} / {L}_{0.5-2\,{\rm{keV}}}^{{\rm{gas}}} − N H and SFR− N H relations.}, archive = {J_ApJ}, author = {Chunyi Zhang and Junfeng Wang}, doi = {10.3847/1538-4357/adf963}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {166}, shortjournal = {The Astrophys. J.}, title = {Global hot gas excess in (Ultra)Luminous infrared galaxies: Replicating galactic nuclei scaling relations between diffuse X-ray emission and star formation on galaxy-wide scales}, volume = {991}, year = {2025}, }
• (2025). Spectroscopic confirmation: Fast rotators in the young clusters NGC 1856 and NGC 1953. ApJ, 991(2), 165. (www)

  @article{ , abstract = {We present the results of a spectroscopic investigation of two Large Magellanic Cloud globular clusters, NGC 1953 and NGC 1856. Both clusters have similar ages (250 and 300 Myr, respectively). Spectra were recorded with the Michigan/Magellan Fiber System located on the Magellan–Clay 6.5 m telescope. Spectra were visually inspected to assess the presence of stellar H α emission lines attributed to B stars rotating close to breakup velocity (Be stars). High fractions of Be stars in the cluster typically indicate the presence of a large population of fast rotating stars, predicted by some models to explain the observed split and extended main sequence. There are numerous Be star candidates in NGC 1856, exhibiting weak but broad H α emission. However, only one such target was detected in NGC 1953. This stark contrast between the observed populations for NGC 1856 and NGC 1953 may suggest that cluster density plays a key role in determining the fraction of Be stars. These results provide essential constraints for the different scenarios attempting to explain the bimodal distribution of rotational velocities and the multiple populations of stars observed in globular clusters. The impact of stellar radial velocity and nebular emission on photometric measures is assessed through simulations relying on the spectra. These simulations suggest that photometric studies can underestimate the fraction of H α emitters in a cluster, in particular for stars with relatively weak emission features. The results also show that nebular emission has minimal impact on the photometric H α excesses.}, archive = {J_ApJ}, author = {Paul I. Cristofari and Andrea K. Dupree and Antonino P. Milone and Mario Mateo and Matias Chiarpotti}, doi = {10.3847/1538-4357/adfb5e}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {165}, shortjournal = {The Astrophys. J.}, title = {Spectroscopic confirmation: Fast rotators in the young clusters NGC 1856 and NGC 1953}, volume = {991}, year = {2025}, }
• (2025). Determining the magnetic field of active region plages using the whole CLASP2/2.1 spectral window. ApJ, 991(2), 164. (www)

  @article{ , abstract = {The Chromospheric LAyer SpectroPolarimeter missions, CLASP2 and CLASP2.1, demonstrated that the near-UV spectral region between 279.30 and 280.68 nm is suitable for studying the magnetism of the solar chromosphere. In particular, the spectropolarimetric observations in the Mg ii h and k resonant doublet, Mn i 279.91 and 280.19 nm resonant lines, and Fe ii 279.79 and 280.66 nm lines acquired by these suborbital space experiments have been proven useful for inferring the magnetic field stratification in the solar chromosphere. However, several lines of the CLASP2/2.1 spectral region with significant circular polarization signals had remained unexplored. After identifying two Ni i (279.95 and 280.59 nm) lines, one Mn ii (280.62 nm) line, and one Fe i (280.53 nm) line, here we apply the weak-field approximation to the spectropolarimetric observations of active region plages by CLASP2 and CLASP2.1. By comparing the results with previous studies, we are able to estimate the formation heights of these CLASP2/2.1 additional spectral lines and to demonstrate their suitability to determine the magnetic field stratification from the photosphere to the upper chromosphere.}, archive = {J_ApJ}, author = {David Afonso Delgado and Tanausú del Pino Alemán and Javier Trujillo Bueno and Ryohko Ishikawa and Ernest Alsina Ballester and David E. McKenzie and Luca Belluzzi and Christian Bethge and Ken Kobayashi and Takenori J. Okamoto and Laurel A. Rachmeler and Donguk Song and Jiří Štěpán and Bart de Pontieu and Adam R. Kobelski and Genevieve D. Vigil and Frédéric Auchère and Ryouhei Kano and Amy Winebarger}, doi = {10.3847/1538-4357/adfcd4}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {164}, shortjournal = {The Astrophys. J.}, title = {Determining the magnetic field of active region plages using the whole CLASP2/2.1 spectral window}, volume = {991}, year = {2025}, }
• (2025). FAST drift scan survey for h i intensity mapping: Simulation of bayesian-stacking-based h i mass function estimation. ApJ, 991(2), 163. (www)

  @article{ , abstract = {This study investigates the estimation of the neutral hydrogen (H i ) mass function (H i MF) using a Bayesian stacking approach with simulated data for the Five-hundred-meter Aperture Spherical radio Telescope (FAST) H i intensity mapping (H i IM) drift-scan surveys. Using data from the IllustrisTNG simulation, we construct H i sky cubes at redshift z ∼ 0.1 and the corresponding optical galaxy catalogs, simulating FAST observations under various survey strategies, including pilot, deep-field, and ultradeep-field surveys. The H i MF is measured for distinct galaxy populations—classified by optical properties into red, blue, and bluer galaxies—and injected with systematic effects such as observational noise and flux confusion caused by the FAST beam. The results show that Bayesian stacking significantly enhances H i MF measurements. For red and blue galaxies, the H i MF can be well constrained with pilot surveys, while deeper surveys are required for the bluer galaxy population. Our analysis also reveals that sample variance dominates over observational noise, emphasizing the importance of wide-field surveys to improve constraints. Furthermore, flux confusion shifts the H i MF toward higher masses, which we address using a transfer function for correction. Finally, we explore the effects of intrinsic sample incompleteness and propose a framework to quantify its impact. This work lays the groundwork for future H i MF studies with FAST H i IM, addressing key challenges and enabling robust analyses of H i content across galaxy populations.}, archive = {J_ApJ}, author = {Jiaxin Wang and Yichao Li and Hengxing Pan and Furen Deng and Diyang Liu and Wenxiu Yang and Wenkai Hu and Yougang Wang and Xin Zhang and Xuelei Chen}, doi = {10.3847/1538-4357/adf10c}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {163}, shortjournal = {The Astrophys. J.}, title = {FAST drift scan survey for h i intensity mapping: Simulation of bayesian-stacking-based h i mass function estimation}, volume = {991}, year = {2025}, }
• (2025). XMM-newton view of pulsating iron fluorescent emission from centaurus X-3. ApJ, 991(2), 162. (www)

  @article{ , abstract = {Centaurus X–3 (Cen X–3) is a bright, high-mass X-ray binary pulsar. We present a pulse phase–resolved X-ray spectral analysis of data from an archival XMM-Newton observation of Cen X–3 taken during the high state of the source. The observation was entirely in the out-of-eclipse part of the binary orbit. We study the pulse phase variability of the three K α fluorescent emission lines from near-neutral, helium-like, and hydrogen-like iron, along with the iron K β emission line. All four lines show clear modulation with the pulse phase of the neutron star (NS), and modulation is found to be higher for the lines from highly ionised iron compared to the neutral lines. Structures within the light travel distance corresponding to the pulse period of the NS are likely responsible for the pulse phase modulation of the emission lines. We have also investigated the orbital phase dependence of the pulse phase variability in the iron lines by dividing the data into four segments at different orbital phases of Cen X–3. The pulse phase modulation behavior of the four lines is quite identical at different orbital phases of Cen X–3, indicating the pulsed iron emission region is persistent in nature and probably phase aligned with respect to the observer. The accretion stream intercepting the line of sight can probably produce the observed phase dependence of the iron fluorescence emission lines.}, archive = {J_ApJ}, author = {Kinjal Roy and Hemanth Manikantan and Biswajit Paul}, doi = {10.3847/1538-4357/adf8e6}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {162}, shortjournal = {The Astrophys. J.}, title = {XMM-newton view of pulsating iron fluorescent emission from centaurus X-3}, volume = {991}, year = {2025}, }
• (2025). Evolution of LISA observables for binary black holes lensed by a supermassive black hole. ApJ, 991(2), 161. (www)

  @article{ , abstract = {Binary black holes (BBHs) are expected to form and merge in active galactic nuclei (AGN), deep in the potential well of a supermassive black hole (SMBH), from populations that exist in a nuclear star cluster. Here we investigate the gravitational-wave (GW) signature of a BBH lensed by a nearby SMBH. For a fiducial GW150914-like BBH orbiting close to a 10 8 M ⊙ SMBH located at z = 0.1, the lensed GW signal varies in a predictable manner in and out of the Laser Interferometer Space Antenna (LISA) detectability band and across frequencies. The occurrence of such signatures has the potential to confound LISA global fit models if they are not modeled. Detection of these sources provides an independent measure of AGN inclination angles, along with detecting warping of the inner disk and measuring the SMBH spin.}, archive = {J_ApJ}, author = {Jake Postiglione and K. E. Saavik Ford and Henry Best and Barry McKernan and Matthew O’Dowd}, doi = {10.3847/1538-4357/adfa0c}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {161}, shortjournal = {The Astrophys. J.}, title = {Evolution of LISA observables for binary black holes lensed by a supermassive black hole}, volume = {991}, year = {2025}, }
• (2025). Early evolution of the cavity and core of a coronal mass ejection in the inner corona. ApJ, 991(2), 160. (www)

  @article{ , abstract = {Coronal mass ejections (CMEs) typically exhibit a three-component structure in white-light (WL) coronagraphs. Utilizing the seamless observations of the inner corona (≤3 R ⊙ ), we have revealed the early evolution of the cavity and core of a CME starting at ∼18:20 UT on 2014 October 14. The CME originates from a hot channel (HC), which appears as the bright core and compresses the cavity in WL images. Specifically, most of the dark cavity in WL is filled by bright loop-like structures in 174 Å. The differential emission measure analysis indicates that the electron temperature decreases from the core (∼13.4 MK) to the cavity (∼1.35 MK), and the CME cavity is significantly cooler than that enshrouding a prominence (≥2 MK). The effective temperature of the cavity increases over time in general, probably due to the compression by the HC expansion. The evolution of the CME bright core includes slow-rise, fast-rise (up to ∼330 km s −1 ), and residual-acceleration phases. The cavity exhibits an evolution similar to the core but lags by ∼4 minutes, with a lower speed peaking at ∼220 km s −1 . Moreover, the 2D radial speed distribution exhibits the highest speeds at the core apex. The kinematical results further confirm the compression of the cavity. The present event supports the new explanation of the CME structures, i.e., the magnetic flux rope (MFR), which is proxied by the HC, is only responsible for the core, while the cavity is likely a low-density region between the CME front and the MFR.}, archive = {J_ApJ}, author = {Shuting Li and Li Feng and Beili Ying and Hongqiang Song and Guanglu Shi and Jiahui Shan and Jie Zhao and Weiqun Gan}, doi = {10.3847/1538-4357/adfbf1}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {160}, shortjournal = {The Astrophys. J.}, title = {Early evolution of the cavity and core of a coronal mass ejection in the inner corona}, volume = {991}, year = {2025}, }
• (2025). Effects of crystal orientation and temperature on space irradiation of silicates. ApJ, 991(2), 159. (www)

  @article{ , abstract = {Space irradiation plays a crucial role in surface weathering and hydration processes of airless bodies in the solar system. Despite extensive laboratory studies, the impact of crystal orientation and temperature on these irradiation processes remains poorly understood. In this study, we conducted hydrogen-implantation experiments on olivine crystals, controlling both crystal orientation and temperature. Our results reveal that the amount and depth of implanted hydrogen depend on the crystal orientation. Olivine exhibits the largest resistance to ion irradiation along the [100] direction, resulting in a thinner damaged region (∼180–200 nm) and subsurface vesicle formation. In contrast, the [010] and [001] orientations allow deeper damage (∼200–210 nm) accompanied by fracturing. Additionally, increasing temperatures from 25°C to 200°C promote the saturation and retention of implanted hydrogen. However, above a critical temperature (∼200°C for olivine), hydrogen levels stabilize, and no further increase is observed. These findings highlight the critical role of crystal orientation and temperature in the irradiation process, providing important constraints for numerical models simulating the effects of space irradiation on rocky bodies.}, archive = {J_ApJ}, author = {Xiandi Zeng and Ziliang Jin and Maitrayee Bose and Richard Hervig and Tao Long}, doi = {10.3847/1538-4357/adfec9}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {159}, shortjournal = {The Astrophys. J.}, title = {Effects of crystal orientation and temperature on space irradiation of silicates}, volume = {991}, year = {2025}, }
• (2025). Can a hybrid star with constant sound speed parameterization explain the new NICER Mass–Radius measurements?. ApJ, 991(2), 158. (www)

  @article{ , abstract = {We present a reanalysis of Neutron Star Interior Composition Explorer observations of PSR J0740+6620 and PSR J0030+0451 in order to test the consistency of various nuclear equations of state (EoSs) within the framework of hybrid star models. In particular, we examine how different surface temperature models for PSR J0030+0451, categorized as scenarios A, B, and C, lead to significantly different mass–radius estimates. We present a comprehensive study constraining the parameters of the constant speed of sound (CSS) model based on representative observational categories. Our findings indicate that for certain hadronic EoSs (for representative cases, we chose one density-independent and one density-dependent), the results remain consistent for lower values of the energy density discontinuity, but discrepancies emerge as the discontinuity increases. Scenarios involving large jumps in energy density are generally disfavored by the requirement of supporting massive neutron stars, while higher values of the speed of sound in the quark matter phase tend to yield better agreement with various observational trends. These results underscore the importance of phase transition characteristics in aligning hybrid star models with current astrophysical observations. We have also constrained the CSS parameters using observational data from PSR J0740+6620 and PSR J0952–0607 by computing the maximum mass supported by these parameters.}, archive = {J_ApJ}, author = {Suman Pal and Gargi Chaudhuri}, doi = {10.3847/1538-4357/adf6a7}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {158}, shortjournal = {The Astrophys. J.}, title = {Can a hybrid star with constant sound speed parameterization explain the new NICER Mass–Radius measurements?}, volume = {991}, year = {2025}, }
• (2025). Gone with the wind: JWST-MIRI unveils a strong outflow from the quiescent stellar-mass black hole a0620-00. ApJ, 991(2), 157. (www)

  @article{ , abstract = {We present new observations of the black hole X-ray binary A0620-00 using the Mid-Infrared (MIR) Instrument on the James Webb Space Telescope, during a state where the X-ray luminosity is 9 orders of magnitude below Eddington, and coordinated with radio, near-infrared, and optical observations. The goal is to understand the nature of the excess MIR emission originally detected by Spitzer redward of 8 μ m. The stellar-subtracted MIR spectrum is well modeled by a power law with a spectral index of α = 0.72 ± 0.01, where the flux density scales with frequency as F ν ∝ ν α . The spectral characteristics, along with rapid variability—a 40% flux flare at 15 μ m and 25% achromatic variability in the 5–12 μ m range—rule out a circumbinary disk as the source of the MIR excess. The Low Resolution Spectrometer reveals a prominent emission feature at 7.5 μ m, resulting from the blend of three hydrogen recombination lines. While the contribution from partially self-absorbed synchrotron radiation cannot be ruled out, we argue that thermal bremsstrahlung from a warm (a few tens of thousands of Kelvin) wind accounts for the MIR excess; the same outflow is responsible for the emission lines. The inferred mass outflow rate indicates that the system’s low luminosity is due to a substantial fraction of the mass supplied by the donor star being expelled through a wind rather than accreted onto the black hole.}, archive = {J_ApJ}, author = {Zihao Zuo and Gabriele Cugno and Joseph Michail and Elena Gallo and David M. Russell and Richard M. Plotkin and Fan Zou and M. Cristina Baglio and Piergiorgio Casella and Fraser J. Cowie and Rob Fender and Poshak Gandhi and Sera Markoff and Federico Vincentelli and Fraser Lewis and Jon M. Miller and James C.A. Miller-Jones and Alexandra Veledina}, doi = {10.3847/1538-4357/adf6b9}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {157}, shortjournal = {The Astrophys. J.}, title = {Gone with the wind: JWST-MIRI unveils a strong outflow from the quiescent stellar-mass black hole a0620-00}, volume = {991}, year = {2025}, }
• (2025). Parallel alignments between magnetic fields and dense structures in the central molecular zone. ApJ, 991(2), 156. (www)

  @article{ , abstract = {The recent Far-Infrared Polarimetric Large-Area Central Molecular Zone Exploration (FIREPLACE) survey with SOFIA has mapped plane-of-sky magnetic field orientations within the Central Molecular Zone (CMZ) of the Milky Way. Applying the Histogram of Relative Orientations analysis to the FIREPLACE data, we find that the relative orientation between magnetic fields and column density structures is random in low-density regions ( 2\times 1{0}^{22}\lesssim {N}_{{{\rm{H}}}_{2}}\lesssim 1{0}^{23}\,{{\rm{cm}}}^{-2} ) but becomes preferentially parallel in high-density regions (≳10 23 cm −2 ). This trend is in contrast with that of the nearby molecular clouds, where the relative orientation transitions from parallel to perpendicular with increasing column densities. However, the relative orientation varies between individual CMZ clouds. Comparisons with magnetohydrodynamic simulations specific to the CMZ conditions suggest that the observed parallel alignment is intrinsic, rather than artifacts caused by the projection effect. The origin of this parallel configuration may arise from the fact that most dense structures in the CMZ are not self-gravitating, as they are in supervirial states, except for the ministarburst region Sgr B2. These findings are consistent with the low star formation efficiency observed in the CMZ compared to that in the Galactic disk.}, archive = {J_ApJ}, author = {Xing Pan and Qizhou Zhang and Keping Qiu and Dylan M. Paré and David T. Chuss and Natalie O. Butterfield and Robin G. Tress and Mattia C. Sormani and Yuping Tang and Steven N. Longmore and Thushara Pillai}, doi = {10.3847/1538-4357/adf8c7}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {156}, shortjournal = {The Astrophys. J.}, title = {Parallel alignments between magnetic fields and dense structures in the central molecular zone}, volume = {991}, year = {2025}, }
• (2025). Statistical properties of a polarization vector’s ellipticity angle. ApJ, 991(2), 155. (www)

  @article{ , abstract = {The orientation of a polarization vector on the Poincaré sphere is defined by its position angle (PA) and ellipticity angle (EA). The radio emission from pulsars, magnetars, and fast radio bursts can be elliptically polarized, and measurements of the EA have become increasingly important in interpretations and models of their polarization. An in-depth understanding of the statistical properties of the measured polarization angles is a prerequisite to their detailed interpretation. While the statistics of the PA have been understood for some time, the statistics of the EA do not appear to be as well developed as those of the PA. The statistical properties of the EA are derived when the amplitude of the polarization vector is constant, to include its probability density, mean, standard deviation, and confidence limits. Similar to the PA, the standard deviation and confidence limits of the EA vary inversely with the polarization signal-to-noise ratio. However, unlike the PA, the probability density of the EA is generally asymmetric, its standard deviation and confidence limits are dependent upon the intrinsic value of the EA, and the measured EA is biased by the instrumental noise, particularly at low signal-to-noise ratios and large values of the intrinsic EA. General expressions for the joint probability density of the polarization angles and the probability density of the EA are also derived when the amplitude of the polarization vector fluctuates due to the superposition of incoherent modes of orthogonal polarization.}, archive = {J_ApJ}, author = {M. M. McKinnon}, doi = {10.3847/1538-4357/adfa29}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {155}, shortjournal = {The Astrophys. J.}, title = {Statistical properties of a polarization vector’s ellipticity angle}, volume = {991}, year = {2025}, }
• (2025). Planetary nebulae in the eROSITA eRASS1 catalog. ApJ, 991(2), 154. (www)

  @article{ , abstract = {Some planetary nebulae (PNs) host X-ray-emitting hot bubbles shaped by stellar wind interactions and/or harbor X-ray-emitting central stars due to accretion, shocks within their fast stellar winds, or even chromospheric emission from binary companions. In both cases, the properties of the X-ray emission critically probe late stages of stellar evolution for such low- and intermediate-mass stars. While extant Chandra and XMM-Newton observations have detected X-ray emission in PNs, the numbers known remain very small (∼40) compared to the overall Galactic PNs population (∼4000). We have initiated a project aimed at increasing the sample of known PNs with X-ray emission using both current and new space-based X-ray telescopes, such as the Einstein probe. To further investigate their X-ray properties to elucidate what drives current X-ray PN detections, we have cross-searched the SRG eROSITA-DE eRASS1 source catalog and the Hong Kong (HASH) PNs Database. Five known X-ray PNs have been detected (A30, NGC 2392, NGC 3242, NGC 5315, and LoTr 5), two new X-ray PNs are revealed (IC 1297 and NGC 2867), one (K 1–27) is removed from previous X-ray compilations, and another 11 previously detected X-ray emitting PNs are not recovered. A comparison of the X-ray flux of detected and undetected X-ray PNs reveals that eROSITA eRASS1 is sensitive to PNs with X-ray fluxes larger than ≈2 × 10 −14 erg cm −2 s −1 . The frequency of occurrence is ≃0.5% among the 1430 HASH True PNs in the eRASS1 footprint.}, archive = {J_ApJ}, author = {Haoyang Yuan and Martin A. Guerrero and Quentin A. Parker and Rodolfo Montez}, doi = {10.3847/1538-4357/adfbe7}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {154}, shortjournal = {The Astrophys. J.}, title = {Planetary nebulae in the eROSITA eRASS1 catalog}, volume = {991}, year = {2025}, }
• (2025). A monte carlo simulation on the scattering coefficients of solar radio wave propagation. ApJ, 991(2), 153. (www)

  @article{ , abstract = {Radio waves undergo scattering by small-scale density fluctuations during propagation through the solar-terrestrial environment, substantially affecting the observed characteristics of solar radio bursts. This scattering process can be effectively modeled as photon diffusion in phase space. In this study, we present a comprehensive comparison between the quasilinear diffusion coefficients and those calculated by ray-tracing the photon trajectories in numerically generated, broadband, isotropic density fluctuation fields in both 2D and 3D configurations. The comparative analysis demonstrates that for weak scattering, the simulated diffusion coefficients agree well with the quasilinear theoretical predictions. However, when the radio frequency approaches the electron plasma frequency and/or the density fluctuation amplitude becomes significant, photons experience strong scattering. Under such conditions, the quasilinear theory tends to underestimate the scattering strength of photons induced by 2D density fluctuations while overestimating the scattering strength in 3D cases. Furthermore, we implement a group velocity correction to the theoretical diffusion coefficients, based on the effective propagation speed averaged over all test photons. The corrected coefficients provide an accurate quantification of the scattering strength for radio waves propagating through 3D density fluctuations. The physical mechanisms underlying these phenomena are elucidated in the discussion.}, archive = {J_ApJ}, author = {Jiazhen Gan and Chuanbing Wang}, doi = {10.3847/1538-4357/adfbe8}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {153}, shortjournal = {The Astrophys. J.}, title = {A monte carlo simulation on the scattering coefficients of solar radio wave propagation}, volume = {991}, year = {2025}, }
• (2025). The wrath of KAN: Enabling fast, accurate, and transparent emulation of the global 21 cm cosmology signal. ApJ, 991(2), 152. (www)

  @article{ , abstract = {Based on the Kolmogorov–Arnold network (KAN), we present a novel emulator of the global 21 cm cosmology signal, 21 cm KAN, that provides extremely fast training speed while achieving nearly equivalent accuracy to the most accurate emulator to date, 21 cm LSTM. The combination of enhanced speed and accuracy facilitated by 21 cm KAN enables rapid and highly accurate physical parameter estimation analyses of multiple 21 cm models, which is needed to fully characterize the complex feature space across models and produce robust constraints on the early Universe. Rather than using static functions to model complex relationships like traditional fully connected neural networks do, KANs learn expressive transformations that can perform significantly better for low-dimensional physical problems. 21 cm KAN predicts a given signal for two well-known models in the community in 3.7 ms on average and trains about 75 times faster than 21 cm LSTM, when utilizing the same typical GPU. In addition, 21 cm KAN is able to achieve these speeds because of its learnable, data-driven transformations and its relatively small number of trainable parameters compared to a memory-based emulator. We show that 21 cm KAN required less than 30 minutes to train and fit these simulated signals and obtain unbiased posterior distributions. We find that the transparent architecture of 21 cm KAN allows us to conveniently interpret and further validate its emulation results in terms of the sensitivity of the 21 cm signal to each physical parameter. This work demonstrates the effectiveness of KANs and their ability to more quickly and accurately mimic expensive physical simulations in comparison to other types of neural networks.}, archive = {J_ApJ}, author = {J. Dorigo Jones and B. Reyes and D. Rapetti and Shah Mohammad Bahauddin and J. O. Burns and D. W. Barker}, doi = {10.3847/1538-4357/adfc49}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {152}, shortjournal = {The Astrophys. J.}, title = {The wrath of KAN: Enabling fast, accurate, and transparent emulation of the global 21 cm cosmology signal}, volume = {991}, year = {2025}, }
• (2025). Blue supergiants in the pinwheel galaxy m101: Comparison with h II region chemical abundances, spectroscopic distance, and an independent determination of the hubble constant. ApJ, 991(2), 151. (www)

  @article{ , abstract = {We present a quantitative spectroscopic study of 13 blue supergiant stars in the Pinwheel Galaxy M101, based on data obtained with the Low Resolution Imaging Spectrometer available at the Keck I telescope. The average stellar metallicity decreases from ∼1.9 Z ⊙ near the center of the galaxy to ∼0.3 Z ⊙ at the optical outskirts. The galactocentric radial metallicity gradient is statistically consistent with previous studies of the gas-phase oxygen abundance from H ii regions using the direct method. The H ii region-based Cepheid metallicities used by A. G. Riess et al. in their determination of the Hubble constant H 0 are in substantial agreement with our measurements. The direct method gas-phase metallicities of the 18 star-forming galaxies we have analyzed so far, when adjusted upward for a mean ∼0.15 dex oxygen dust depletion factor, are in good agreement with those we infer from the supergiants, over a factor of 50 in metallicity. From the same data, we derive an expression for the metal-dependent depletion of oxygen in photoionized nebulae. Utilizing the flux-weighted gravity–luminosity relationship (FGLR) of blue supergiants, we measure a distance to M101, D = 6.5 ± 0.2 Mpc ( μ = 29.06 ± 0.08), which is within 1 σ from determinations based on the tip of the red giant branch and Cepheids. With M101 as a nearby Type Ia supernova host and using the observed standardized B -band magnitude of the supernova, our FGLR distance yields an independent value of H 0 = 72.5 ± 4.6 km s −1 Mpc −1 .}, archive = {J_ApJ}, author = {Fabio Bresolin and Rolf-Peter Kudritzki and Miguel A. Urbaneja and Eva Sextl and Adam G. Riess}, doi = {10.3847/1538-4357/adfc4c}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {151}, shortjournal = {The Astrophys. J.}, title = {Blue supergiants in the pinwheel galaxy m101: Comparison with h II region chemical abundances, spectroscopic distance, and an independent determination of the hubble constant}, volume = {991}, year = {2025}, }
• (2025). Investigating multiband variability characteristics of the typical BLSy1 mrk 1220 through intensive swift monitoring. ApJ, 991(2), 150. (www)

  @article{ , abstract = {Broad-line Seyfert 1 galaxies (BLSy1s), characterized by high black hole masses and low accretion rates, represent a crucial subclass of active galactic nuclei. We present a systematic analysis of the variability and X-ray spectral properties of the BLSy1 Mrk 1220 using 225 high-quality Swift observations from 2016 to 2018. Mrk 1220 exhibits significant multiwavelength variability across X-ray, ultraviolet (UV), and optical bands, with amplitude increasing with energy but remaining weaker than narrow-line Seyfert 1 galaxies (NLSy1s) with high accretion rates. Cross-correlation analysis reveals no significant interband time delays. The UV/optical–X-ray correlation weakens with increasing wavelength, with a maximum correlation coefficient of only 0.54. The relatively weak UV/X-ray connection may be attributed to the dynamic evolution of the coronal structure. Structure function (SF) analysis reveals a distinctive double “S” structure in optical/UV bands. Short-timescale SF parameters resemble those of NLSy1s, while X-ray bands show significantly longer decorrelation timescales, indicating an extended X-ray corona. SF spectral coefficients ( β ) across bands generally follow the damped random walk model, with only the U -band long-timescale β slightly elevated, potentially influenced by broad-line region radiation. X-ray spectral characteristics remain consistent between high and low flux states, showing weak soft excess below 1 keV. The stability of the soft excess parameters and power-law spectral index suggests unchanged coronal geometry across states, with X-ray variations primarily driven by intrinsic electron density fluctuations. These results provide valuable observational constraints for understanding the variability mechanisms and spectral characteristics of typical BLSy1s.}, archive = {J_ApJ}, author = {Keli Peng and Nan Ding and Yunyong Tang and Jin Cao}, doi = {10.3847/1538-4357/adfdd0}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {150}, shortjournal = {The Astrophys. J.}, title = {Investigating multiband variability characteristics of the typical BLSy1 mrk 1220 through intensive swift monitoring}, volume = {991}, year = {2025}, }
• (2025). Meridional circulation. II. a unified mechanism for lithium depletion in solar analogs and the lithium dip in mid-F cluster stars. ApJ, 991(2), 149. (www)

  @article{ , abstract = {The behavior of lithium (Li) in Population I main-sequence stars challenges standard stellar theory. Two phenomena stand out: the solar Li problem, which extends to Li depletion in solar analogs, and the Li dip observed in mid-F stars within open clusters. Building on the meridional-circulation-driven radial mixing framework previously developed to explain Li-enriched red clump stars, we explore its relevance to Li depletion on the main sequence. First, our models reproduce the observed A (Li)–age correlation in solar analogs. Through detailed isochrone analysis, we find good agreement between the simulated and observed A (Li)– T eff relationships within the solar analog parameter space. However, the predicted solar Li abundance (∼1.5 dex) is still higher than current solar measurements. Second, our models partially explain the Li dip phenomenon in mid-F cluster stars. The models accurately reproduce Li distributions on the cool side of the Li dip in most clusters and capture the Li behaviors on the hot side observed in systems like the Hyades. However, we identify limitations in the models’ ability to fully reproduce the dip morphology, particularly due to the rotation velocity distribution of sample stars in this temperature zone.}, archive = {J_ApJ}, author = {Xue-Feng Li and Jian-Rong Shi and Yan Li and Hong-Liang Yan and Jing-Hua Zhang}, doi = {10.3847/1538-4357/adfdd5}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {149}, shortjournal = {The Astrophys. J.}, title = {Meridional circulation. II. a unified mechanism for lithium depletion in solar analogs and the lithium dip in mid-F cluster stars}, volume = {991}, year = {2025}, }
• (2025). A common origin of normal type ia supernovae suggested by the photometric diversity. ApJ, 991(2), 148. (www)

  @article{ , abstract = {In recent years, with the increasing number of type Ia supernovae (SNe Ia) discovered soon after their explosions, a nonnegligible fraction of SNe Ia with early-excess emissions (EExSNe Ia) have been confirmed. In this paper, we present a total of 67 early-phase normal SNe Ia from published papers and ongoing transient survey projects to systematically investigate their photometric behaviors from very early time. We found that EExSNe Ia in our sample have longer rise and brighter peak luminosities compared to non-EExSNe Ia. Moreover, EExSNe Ia commonly have “tiny red bump” or “blue plateau” features in the early B − V color while non-EExSNe Ia show blueward evolution from the very beginning. Here, we propose that the thin He-shell double detonation scenario can phenomenologically explain the photometric diversities of normal SNe Ia considering different white dwarf–He-shell mass combinations and the viewing angle effect, implying a unified explosion mechanism of normal-type SNe Ia. To further verify the possible common origin of normal SNe Ia, systematical studies of multiband photometric and spectral properties of early-phase SNe Ia through the new-generation wide-field time-domain survey facilities and global real-time follow-up networks are highly needed.}, archive = {J_ApJ}, author = {Weiyu Wu and Ji-an Jiang and Dezheng Meng and Zelin Xu and Keiichi Maeda and Mamoru Doi and Ken’ichi Nomoto and Naoki Yasuda and Masaomi Tanaka and Toshikazu Shigeyama and Nozomu Tominaga and Željko Ivezić and Peter Yoachim and Saurabh W. Jha and Tinggui Wang and Hisanori Furusawa and Nao Suzuki and Andrew J. Connolly and Satoshi Miyazaki}, doi = {10.3847/1538-4357/adf05a}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {148}, shortjournal = {The Astrophys. J.}, title = {A common origin of normal type ia supernovae suggested by the photometric diversity}, volume = {991}, year = {2025}, }
• (2025). QPEs from EMRI debris streams impacting accretion disks in galactic nuclei. ApJ, 991(2), 147. (www)

  @article{ , abstract = {Quasi-periodic eruption (QPE) sources in galactic nuclei are often associated with a stellar object orbiting a supermassive black hole with an hours to days period, which is brought in as an extreme mass-ratio inspiral (EMRI). In the presence of an accretion disk, repeated star–disk collisions lead to ablation of a small fraction of the stellar mass during each disk passage. We analytically track stellar debris as it is tidally stretched outside the EMRI’s Hill sphere, forming an elongated, dilute stream that collides with the disk half an orbit after the last star–disk encounter. For orbital periods ≳12 hr, the dilute stream is deflected at the disk surface by a strong shock, rather than penetrating it. Due to their low optical depth and prolonged interaction time, radiation from the shocked streams typically dominates over emission from shocked disk gas directly impacted by the star. We find that (1) QPE flare durations reflect the stream–disk collision timescale; (2) flare luminosities of 10 42−43 erg s −1 , consistent with observed QPEs, are robustly produced; (3) soft X-ray flares with temperatures of ∼100 eV arise when the stream mass is sufficient to sustain a radiation-mediated shock at the collision interface. Higher-mass streams yield softer flares, typically outshone by the disk, while lower-mass streams result in collisionless shocks, which likely produce fainter and harder flares. We discuss observational implications of the temporal evolution of the underlying disk, assuming it is the remnant of a prior tidal disruption event in the same galaxy.}, archive = {J_ApJ}, author = {Itai Linial and Brian D. Metzger and Eliot Quataert}, doi = {10.3847/1538-4357/adfa0e}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {147}, shortjournal = {The Astrophys. J.}, title = {QPEs from EMRI debris streams impacting accretion disks in galactic nuclei}, volume = {991}, year = {2025}, }
• (2025). Mass segregation and transient formation in nuclear stellar clusters. ApJ, 991(2), 146. (www)

  @article{ , abstract = {Supermassive black holes at the centers of galaxies occasionally disrupt stars or consume stellar-mass black holes (BHs) that wander too close, producing observable electromagnetic or gravitational wave signals. We examine how mass segregation impacts the rates and distributions of such events. Assuming a relaxed stellar cluster, composed of stars and stellar-mass BHs, we show that the tidal disruption rate of massive stars ( m ≳ M ⊙ ) is enhanced relative to their abundance in the stellar population. For stars up to m ≈ 3 M ⊙ , this enhancement is roughly m / M ⊙ and it is driven by segregation within the sphere of influence. Stars with masses m ≳ 3 M ⊙ , if relaxed, are predominantly scattered by more massive stellar-mass BHs, leading to a constant enhancement factor of ≈9, independent of mass. This aligns with observational evidence suggesting an over-representation of massive stars in tidal disruption events. For stellar-mass BHs, we predict an enhancement factor scaling as {m}_{\bullet }^{1/2} for plunges and {m}_{\bullet }^{3/2} for extreme-mass-ratio inspirals (EMRIs). The power of one-half in both cases reflects the shorter relaxation times of heavier BHs, allowing them to segregate into the sphere of influence from greater distances, thereby increasing their abundance. The additional power in the EMRIs’ rate arises from the tendency of heavier BHs to circularize and sink inward more efficiently. Finally, we estimate the rate of main-sequence star inspirals and find that it favors low-mass stars ( m ≲ M ⊙ ). This seems compatible with the observationally estimated rate of quasiperiodic eruptions.}, archive = {J_ApJ}, author = {Barak Rom and Re’em Sari}, doi = {10.3847/1538-4357/adfb6c}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {146}, shortjournal = {The Astrophys. J.}, title = {Mass segregation and transient formation in nuclear stellar clusters}, volume = {991}, year = {2025}, }
• (2025). Reconstruction of X-ray afterglow light curves of gamma-ray bursts and its implication on constraining cosmological parameters. ApJ, 991(2), 145. (www)

  @article{ , abstract = {Gamma-ray bursts (GRBs) serve as important cosmological probes whose X-ray afterglow light curves (LCs) may exhibit a plateau phase (with temporal slope α between 0 and 0.5) that may originate from magnetar energy injection. Similar to Type Ia supernovae, GRBs with a common physical origin can be used as standardizable candles for cosmological studies. However, observational gaps in GRB LCs introduce significant uncertainties in plateau parameter estimation, thereby affecting cosmological constraints. In this work, we employ a stochastic reconstruction technique to reconstruct the X-ray afterglow LCs for 35 GRB samples exhibiting plateau features, generating 50 simulated data points for each LC. Using the reconstructed LCs, we calibrate three luminosity correlations: the L 0 – t b , L 0 – t b – E p , i , and L 0 – t b – E γ ,iso relations, which are then applied to constrain both flat and nonflat ΛCDM cosmological models. The main results include (i) the L 0 – t b relation yields a slope b ≈ −1, supporting a constant magnetar energy injection rate; (ii) LC reconstruction has limited impact on cosmological parameter constraints; and (iii) for the flat ΛCDM model constrained by the L 0 – t b – E p , i relation, the precision of Ω m improves by 6.25%; for the non-flat ΛCDM model constrained by the L 0 – t b – E p , i relation, the precision of Ω Λ improves by 1.01%. Our findings suggest that increasing the number of LC data points provides limited improvement to cosmological constraints, while expanding the sample size of GRBs with identical physical origins may be more crucial.}, archive = {J_ApJ}, author = {Yu-Qi Zhou and Shuang-Xi Yi and Yu-Peng Yang and Jia-Lun Li and Jian-Ping Hu and Yan-Kun Qu and Fa-Yin Wang}, doi = {10.3847/1538-4357/adfd4f}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {145}, shortjournal = {The Astrophys. J.}, title = {Reconstruction of X-ray afterglow light curves of gamma-ray bursts and its implication on constraining cosmological parameters}, volume = {991}, year = {2025}, }
• (2025). Flat tails in fast radio burst and pulsar energy distributions: Implications for optimizing nearby fast radio burst surveys. ApJ, 991(2), 144. (www)

  @article{ , abstract = {Fast radio bursts (FRBs) are energetic, short-duration radio pulses of unclear origin. To explore effective survey strategies for detecting FRBs from nearby globular clusters (GCs), we investigate the burst energy distribution, which has a strong influence on the detection rate. We reanalyze FRBs and pulsars exhibiting broad energy distributions by fitting their high-energy tails with power-law models. Two cosmological repeating FRBs (FRB 20201124A and FRB 20220912A), one nearby FRB (FRB 20200120E), and two pulsars (RRATs J1846−0257 and J1854+0306) exhibit power-law indices of α ≳ −1, suggesting that their bright pulses contribute significantly to the total radio pulse energy. The brightest bursts from these sources can be fitted with a power-law model ( α Bri = −0.26 ± 0.05), suggesting that an extremely flat index is required to naturally derive high-luminosity FRBs from low-luminosity sources. We present detailed survey strategies for FAST, MeerKAT, and Parkes cryoPAF in the search for FRBs in nearby GCs using different power-law indices, recommending targets for observation. We suggest that combining observations with FAST (∼3 hr) and Parkes cryoPAF (10−20 hr) is practicable for discovering new FRBs in nearby GCs.}, archive = {J_ApJ}, author = {S. B. Zhang and G. Hobbs and S. Johnston and S. Dai and Y. Li and J. S. Wang and X. Yang and X. F. Wu and L. Staveley-Smith}, doi = {10.3847/1538-4357/adfec4}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {144}, shortjournal = {The Astrophys. J.}, title = {Flat tails in fast radio burst and pulsar energy distributions: Implications for optimizing nearby fast radio burst surveys}, volume = {991}, year = {2025}, }
• (2025). Modeling the reverberation response of the broad-line region in active galactic nuclei. II. incorporating photoionization models. ApJ, 991(2), 143. (www)

  @article{ , abstract = {The broad emission lines (BELs) emitted by active galactic nuclei respond to variations in the ionizing continuum emission from the accretion disk surrounding the central supermassive black hole (SMBH). This reverberation response provides insights into the structure and dynamics of the broad-line region (BLR). In 2024, we introduced a new forward-modeling tool, the Broad Emission Line Mapping Code (B ELMAC ), which simulates the velocity-resolved reverberation response of the BLR to an input light curve. In this work, we describe a new version of B ELMAC , which uses photoionization models to calculate the cloud luminosities for selected BELs. We investigated the reverberation responses of H α , H β , Mg II λ 2800, and C IV λ 1550 for models representing a disk-like BLR with Keplerian rotation, radiatively driven outflows, and inflows. The line responses generally provide a good indication of the respective luminosity-weighted radii. However, there are situations where the BLR exhibits a negative response to the driving continuum, causing overestimates of the luminosity-weighted radius. The virial mass derived from the models can differ dramatically from the actual SMBH mass, depending mainly on the disk inclination and velocity field. In single-zone models, the BELs exhibit similar responses and profile shapes; two-zone models, such as a Keplerian disk and a biconical outflow, can reproduce observed differences between high- and low-ionization lines. Radial flows produce asymmetric line profile shapes due to both anisotropic cloud emission and electron scattering in an intercloud medium. These competing attenuation effects complicate the interpretation of profile asymmetries.}, archive = {J_ApJ}, author = {Sara A. Rosborough and Andrew Robinson and Triana Almeyda and Daniel Humphrey and Madison Noll}, doi = {10.3847/1538-4357/adf109}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {143}, shortjournal = {The Astrophys. J.}, title = {Modeling the reverberation response of the broad-line region in active galactic nuclei. II. incorporating photoionization models}, volume = {991}, year = {2025}, }
• (2025). The z ∼ 1.03 merging cluster SPT-CL j0356–5337: New strong lensing analysis with HST and MUSE. ApJ, 991(2), 142. (www)

  @article{ , abstract = {We present a strong lensing analysis and reconstruct the mass distribution of SPT-CL J0356−5337, a galaxy cluster at redshift z = 1.034. Our model supersedes previous models by making use of new multiband Hubble Space Telescope data and Multi-Unit Spectroscopic Explorer (MUSE) spectroscopy. We identify two additional lensed galaxies to inform a more well-constrained model using 12 sets of multiple images in five separate lensed sources. The three previously known sources were spectroscopically confirmed by G. Mahler et al. at redshifts of z = 2.363, z = 2.364, and z = 3.048. We measured the spectroscopic redshifts of two of the newly discovered arcs using MUSE data, at z = 3.0205 and z = 5.3288. We increase the number of cluster member galaxies by a factor of 3 compared to previous work. We also report the detection of extended Ly α emission from several background galaxies. We measure the total projected mass density of the two major subcluster components, one dominated by the brightest cluster galaxy and the other by a compact group of luminous red galaxies. We find {M}_{{\rm{B}}{\rm{C}}{\rm{G}}}(\lt 80\,\rm{kpc})=3.9{3}_{-0.14}^{+0.21}\times 1{0}^{13} M ⊙ and {M}_{{\rm{LRG}}}(\lt 80\,\rm{kpc})=2.9{2}_{-0.23}^{+0.16}\times 1{0}^{13} M ⊙ , yielding a mass ratio of 1.3{5}_{-0.08}^{+0.16} . The strong lensing constraints offer a robust estimate of the projected mass density regardless of modeling assumptions; allowing more substructure in this line of sight does not change the results or conclusions. Our results corroborate the conclusion that SPT-CL J0356−5337 is dominated by two mass components and is likely undergoing a major merger on the plane of the sky.}, archive = {J_ApJ}, author = {Grace Smith and Guillaume Mahler and Kate Napier and Keren Sharon and Matthew Bayliss and Bradford Benson and Lindsey Bleem and Benjamin Floyd and Michael D. Gladders and Gourav Khullar and Tim Schrabback}, doi = {10.3847/1538-4357/adee1f}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {142}, shortjournal = {The Astrophys. J.}, title = {The z ∼ 1.03 merging cluster SPT-CL j0356–5337: New strong lensing analysis with HST and MUSE}, volume = {991}, year = {2025}, }
• (2025). Glimmers in the cosmic dawn. II. a variability census of supermassive black holes across the universe*. ApJ, 991(2), 141. (www)

  @article{ , abstract = {Understanding the origin and evolution of supermassive black holes (SMBHs) stands as one of the most important challenges in astrophysics and cosmology, with little current theoretical consensus. Improved observational constraints on the cosmological evolution of SMBH demographics are needed. Here we report results of a search via photometric variability for SMBHs appearing as active galactic nuclei (AGN) in the cosmological volume defined by the Hubble Ultra Deep Field. This work includes particular focus on a new observation carried out in 2023 with the Hubble Space Telescope using the WFC3/IR/F140W, which is compared directly to equivalent data taken 11 yr earlier in 2012. Two earlier pairs of observations from 2009 to 2012 with WFC3/IR/F105W and WFC3/IR/F160W are also analyzed. We identify 521, 188, and 109 AGN candidates as nuclear sources that exhibit photometric variability at a level of 2 σ , 2.5 σ , and 3 σ , respectively, in at least one filter. This sample includes 13, 3, and 2 AGN candidates at redshifts z > 6, when the Universe was ≲900 Myr old. After variability and luminosity function (down to M UV = −17 mag) completeness corrections, we estimate the comoving number density of SMBHs, n SMBH ( z ). At z ≳ 6, n SMBH ≳ 6 × 10 −3 cMpc −3 . At low z our observations are sensitive to AGN fainter than M UV = −17 mag, and we estimate n SMBH ≳ 10 −2 cMpc −3 . We discuss how these results place strong constraints on a variety of SMBH seeding theories.}, archive = {J_ApJ}, author = {Vieri Cammelli and Jonathan C. Tan and Alice R. Young and Matthew J. Hayes and Jasbir Singh and Richard S. Ellis and Aayush Saxena and Nicolas Laporte and Pierluigi Monaco and Benjamin W. Keller}, doi = {10.3847/1538-4357/adf63b}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {141}, shortjournal = {The Astrophys. J.}, title = {Glimmers in the cosmic dawn. II. a variability census of supermassive black holes across the universe*}, volume = {991}, year = {2025}, }
• (2025). A multilayer perceptron to extend and improve diatomic molecule collision rate coefficients. ApJ, 991(2), 140. (www)

  @article{ , abstract = {A data-driven approach to improve the accuracy of state-resolved molecular collision data for the relaxation of vibrationally and rotationally excited molecules is developed. We apply the approach to the SiO–H 2 collision system, which is crucial for reliable astrophysical environment modeling of SiO emission. The most accurate quantum scattering calculation method employs the coupled-channel formalism, which is computationally expensive. Approximate approaches, generally referred to as decoupling approximations, are significantly more computationally efficient, but less accurate. To bridge this accuracy gap, we use a multilayer perceptron to predict the difference between the accurate and approximate results. Our model is trained on a carefully selected and preprocessed data set, which includes both approximate and accurate calculation results. We show that our approach significantly improves the accuracy of the approximate calculation results, as the relative rms errors from the predicted results are orders of magnitude smaller than those from the approximate calculation results, benchmarked against the accurate calculations. The present approach can be applied to similar problems in other fields to improve the accuracy of computationally efficient approximate methods, reducing computation time and enhancing automation.}, archive = {J_ApJ}, author = {Ruihan Wang and Darin E. Mihalik and Benhui Yang and Phillip C. Stancil and Teri J. Price and Robert C. Forrey and Naduvalath Balakrishnan and Roman V. Krems}, doi = {10.3847/1538-4357/adf6bb}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {140}, shortjournal = {The Astrophys. J.}, title = {A multilayer perceptron to extend and improve diatomic molecule collision rate coefficients}, volume = {991}, year = {2025}, }
• (2025). Inside-out versus upside-down: The origin and evolution of metallicity radial gradients in FIRE simulations of milky way-mass galaxies and the essential role of gas mixing. ApJ, 991(2), 139. (www)

  @article{ , abstract = {Within the Milky Way (MW), younger stellar populations exhibit steeper (more negative) metallicity radial gradients; the origin of this trend remains debated. The FIRE-2 cosmological simulations of MW-mass galaxies show the same trend as the MW, which in FIRE-2 arises because the metallicity gradient of the interstellar medium (ISM), and thus of stars at birth, became steeper over time. We seek to understand this evolution in the context of inside-out radial growth of galaxies. Most FIRE-2 galaxies grew radially from the inside out in both gas and stars; specifically, their surface density profiles, Σ( R ), became shallower over time. Combined with a realized superlinear (Kennicutt–Schmidt-like) relation between star formation and total gas density, the profile of the ratio Σ star ( R )/Σ gas ( R ) became shallower (flatter) over time. Thus, if metals stayed where they were injected into the ISM from stars, the metallicity gradient would become shallower over time, as some models predict. However, metallicity gradients in FIRE-2 became steeper over time because of the additional effects of (radial) mixing of metals in the ISM. Specifically, the velocity dispersion and net radial advection of gas declined over time, as ISM turbulence decreased and the disk settled, leading to upside-down vertical growth. In FIRE-2, this evolution in metal mixing of gas associated with upside-down growth dominates over inside-out radial growth, causing the metallicity radial gradient of the ISM and of stars at birth to become steeper over time. We argue that this reflects the ISM history of typical MW-mass galaxies and a plausible history of the MW.}, archive = {J_ApJ}, author = {Russell L. Graf and Andrew Wetzel and Jeremy Bailin and Matthew E. Orr}, doi = {10.3847/1538-4357/adfa07}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {139}, shortjournal = {The Astrophys. J.}, title = {Inside-out versus upside-down: The origin and evolution of metallicity radial gradients in FIRE simulations of milky way-mass galaxies and the essential role of gas mixing}, volume = {991}, year = {2025}, }
• (2025). Mapping feedback signatures in 3C 297: A quasar-host merger at cosmic noon. ApJ, 991(2), 138. (www)

  @article{ , abstract = {We present a study of quasar host galaxy 3C 297, which is home to a powerful bent-jet radio source suggesting vigorous interaction with a dense interstellar medium (ISM) and/or jet precession. Archival Hubble Space Telescope (HST) imaging showed interestingly perturbed morphology of the host with a bright ∼30 kpc arc feature, extended filamentary structure of line-emitting gas, and clumpy blue excess emission cospatial with the radio hotspots. Our Very Large Telescope (VLA)/SINFONI integral-field observations reveal complex, spatially resolved H α + [N II ] emission in this source. A prominent blueshifted wing in H α indicates an ionized gas flow extending out to ∼8 kpc from the nuclear region. Combining our SINFONI narrow-H α data with archival HST/UV and VLA imaging, we map the young stellar population in the host and compare the spatial distribution of star-forming regions with the ionized gas motion and jet structure. In the attempt to characterize the feedback mechanisms in this chaotic system, we suggest that the powerful radio source dominates the feedback, with possible contribution from radiation pressure due to accretion onto the black hole. We also propose that the expanding jet cocoon likely shocked the ISM, triggering a kpc-scale ionized gas outflow and new starbursts that enhanced ongoing merger-induced star formation.}, archive = {J_ApJ}, author = {C. Duggal and C. P. O’Dea and S. A. Baum and J. Jiwa and G. R. Tremblay and M. Chiaberge and G. Miley and C. Stanghellini and W. Sparks}, doi = {10.3847/1538-4357/adfa98}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {138}, shortjournal = {The Astrophys. J.}, title = {Mapping feedback signatures in 3C 297: A quasar-host merger at cosmic noon}, volume = {991}, year = {2025}, }
• (2025). On the variability features of active galactic nuclei in little red dots. ApJ, 991(2), 137. (www)

  @article{ , abstract = {The high-redshift ( z > 4) compact sources with “V-shaped” spectral energy distributions, known as Little Red Dots (LRDs), were discovered by the James Webb Space Telescope and provide valuable clues to the physics of active galactic nuclei (AGNs) in the early Universe. The nature of LRDs is controversial. Recently, several studies have investigated LRDs through variability, a characteristic feature of AGNs. These studies explore LRD variability by extrapolating empirical relationships from local quasars. Here, we adopt the Corona-heated Accretion-disk Reprocessing (CHAR) model, which is motivated by accretion physics and is applicable to reproducing AGN conventional variability, to study the variability of 22 LRDs in W. L. Tee et al. Our results indicate that the observed variability in LRDs is dominated by measurement uncertainties. Within the CHAR model, the lack of variability in LRDs can be explained by two scenarios: either AGNs contribute ≲30% of the observed luminosities, or they are intrinsically luminous AGNs. We use simulations to demonstrate the observational requirements to effectively investigate LRDs via variability with the following criteria: first, the sample has about 200 LRDs; second, each LRD has two observations separated by at least 2 yr in the observed frame; third, the photometric uncertainty is ≤0.07 mag. If the LRDs still lack variability under these conditions, the time–domain study would provide independent evidence that the accretion mode of LRDs differs significantly from low-redshift quasars.}, archive = {J_ApJ}, author = {Shuying Zhou and Mouyuan Sun and Zijian Zhang and Jie Chen and Luis C. Ho}, doi = {10.3847/1538-4357/adfd5f}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {137}, shortjournal = {The Astrophys. J.}, title = {On the variability features of active galactic nuclei in little red dots}, volume = {991}, year = {2025}, }
• (2025). Verification of cas a neutron star cooling rate using chandra HRC-S observations. ApJ, 991(2), 136. (www)

  @article{ , abstract = {The young neutron star (NS) in the Cassiopeia A (Cas A) supernova remnant is a fascinating test for theories of NS cooling. Chandra observations have indicated that its surface temperature is declining rapidly, by about 2% per decade, using 20 yr of data, if a uniform carbon atmosphere is assumed for the NS. This rapid decline may be caused by the neutrons in the NS core transitioning from a normal to a superfluid state. However, most of the Cas A NS observations were performed by the Chandra ACIS detectors, which suffer complicated systematic effects. Here, we test the cooling of the Cas A NS with Chandra High Resolution Camera (HRC) data over 25 yr. The Chandra HRC detector has independent systematics, serving as a cross-check. Assuming a fixed hydrogen column density ( N H ), we infer the cooling rate of the Cas A NS to be 0.57 {}_{-0.27}^{+0.26} % per decade. Allowing the N H to vary with time (as estimated using ACIS data), the cooling rate is 1.11 {}_{-0.28}^{+0.25} % per decade. These cooling rates are smaller than measured using ACIS data, implying systematic uncertainties have not been eradicated from either or both data sets. However, we have verified the decline in the absorbed flux from the Cas A NS using an independent instrument, at >3 σ level (4.7% ± 1.5% over 10 yr). Additionally, the weaker cooling rate of Cas A NS inferred from HRC data sets eliminates the tension with the theoretically predicted cooling, and can be explained by the reduced efficiency of the neutrino emission accompanying the Cooper pair breaking and formation process in neutron triplet-state superfluid.}, archive = {J_ApJ}, author = {Jiaqi Zhao and Craig O. Heinke and Peter S. Shternin and Wynn C. G. Ho and Dmitry D. Ofengeim and Daniel Patnaude}, doi = {10.3847/1538-4357/adfdcf}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {136}, shortjournal = {The Astrophys. J.}, title = {Verification of cas a neutron star cooling rate using chandra HRC-S observations}, volume = {991}, year = {2025}, }
• (2025). Deciphering profile stability in millisecond pulsars: Timescales, frequency evolution, and implications on emission mechanisms. ApJ, 991(2), 135. (www)

  @article{ , abstract = {Pulse profile stability in millisecond pulsars (MSPs) is a key factor in achieving high-precision timing essential for detecting nanohertz gravitational waves with pulsar timing arrays (PTAs). In this work, we present a systematic analysis of profile stabilization timescales in MSPs using a direct method based on pulse stacking, applied to long-term multiepoch observations. Our study utilizes data from the upgraded Giant Metrewave Radio Telescope (uGMRT) between 300 and 750 MHz for nine MSPs over 3–5 yr and Parkes Ultra-Wideband, low-frequency receiver observations (covering 704–4032 MHz) for three of them. We find that stable profiles typically require averaging over 10 5 –10 6 pulses. This is the first time such a quantitative approach has been applied to MSPs across a wide frequency range, providing an indirect but practical estimate of jitter noise—a dominant noise source in PTA data sets. We observe that stabilization timescales depend on signal-to-noise ratio, pulse morphology, and surface magnetic field strength, with a moderate correlation indicating a possible role of magnetic field in emission stability. A complementary single-epoch analysis of nine bright MSPs with uGMRT Band-3 (300–500 MHz) reinforces these results and demonstrates the method’s applicability to broader MSP populations. We show that a strong correlation exists between profile-stability slope and the jitter parameter, implying that, for faint MSPs, profile-stability analysis can act as an effective proxy for intrinsic pulse-shape variability. Our work provides a novel and scalable framework to assess intrinsic profile variability, helping to guide integration time choices and reduce timing noise in PTA experiments.}, archive = {J_ApJ}, author = {Ankita Ghosh and Bhaswati Bhattacharyya and Rahul Sharan and Patrick Weltevrede and Jayanta Roy and Sangita Kumari}, doi = {10.3847/1538-4357/adff5a}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {135}, shortjournal = {The Astrophys. J.}, title = {Deciphering profile stability in millisecond pulsars: Timescales, frequency evolution, and implications on emission mechanisms}, volume = {991}, year = {2025}, }
• (2025). Revealing the nature of long-period transients with space-based gravitational-wave interferometers. ApJ, 991(2), 134. (www)

  @article{ , abstract = {A few members of the recently discovered class of long-period transients have been identified as binaries with white-dwarf primaries. In most cases, however, electromagnetic data are inconclusive, and isolated magnetars or compact binaries remain viable. If the pulsation period matches that of the orbit—as is the case for ILT J1101+5521 and GLEAM-X J0704–37—some of these elusive radio transients could be gravitational-wave bright in the mHz band. Space-based interferometers could thus be used to provide independent constraints on their nature. We quantify the signal-to-noise ratio for the known systems under various scenarios and show that a few could be detectable for sufficiently large chirp masses. Astrophysical implications for (non)detections are discussed.}, archive = {J_ApJ}, author = {Arthur G. Suvorov and Clara Dehman and José A. Pons}, doi = {10.3847/1538-4357/adfc55}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {134}, shortjournal = {The Astrophys. J.}, title = {Revealing the nature of long-period transients with space-based gravitational-wave interferometers}, volume = {991}, year = {2025}, }
• (2025). Very late-time JWST and keck spectra of the oxygen-rich supernova 1995N. ApJ, 991(2), 133. (www)

  @article{ , abstract = {We present new JWST/MIRI Medium Resolution Spectroscopy and Keck spectra of SN 1995N obtained in 2022–2023, more than 10,000 days after the supernova (SN) explosion. These spectra are among the latest direct detections of a core-collapse SN, both through emission lines in the optical and thermal continuum from infrared (IR) dust emission. The new IR data show that dust heating from radiation produced by the ejecta interacting with circumstellar matter is still present but greatly reduced from when SN 1995N was observed by the Spitzer Space Telescope and WISE in 2009/2010 and 2018, when the dust mass was estimated to be 0.4 M ⊙ . New radiative-transfer modeling suggests that the dust mass and grain size may have increased between 2010 and 2023. The new data can alternatively be well fit with a dust mass of 0.4 M ⊙ and a much reduced heating source luminosity. The new late-time spectra show unusually strong oxygen forbidden lines, stronger than the H α emission. This indicates that SN 1995N may have exploded as a stripped-envelope SN, which then interacted with a massive H-rich circumstellar shell, changing it from intrinsically Type Ib/c to Type IIn. The late-time spectrum results when the reverse shock begins to excite the inner H-poor, O-rich ejecta. This change in the spectrum is rarely seen but marks the start of the transition from SN to SN remnant.}, archive = {J_ApJ}, author = {Geoffrey C. Clayton and R. Wesson and Ori D. Fox and Melissa Shahbandeh and Alexei V. Filippenko and Bryony Nickson and Michael Engesser and Schuyler D. Van Dyk and WeiKang Zheng and Thomas G. Brink and Yi Yang and Tea Temim and Nathan Smith and Jennifer Andrews and Chris Ashall and Ilse De Looze and James M. Derkacy and Luc Dessart and Michael Dulude and Eli Dwek and Ryan J. Foley and Suvi Gezari and Sebastian Gomez and Shireen Gonzaga and Siva Indukuri and Jacob Jencson and Joel Johansson and Mansi Kasliwal and Zachary G. Lane and Ryan Lau and David Law and Anthony Marston and Dan Milisavljevic and Richard O’Steen and Justin Pierel and Armin Rest and Arkaprabha Sarangi and Matthew Siebert and Michael Skrutskie and Lou Strolger and Tamás Szalai and Samaporn Tinyanont and Qinan Wang and Brian Williams and Lin Xiao and Szanna Zsíros}, doi = {10.3847/1538-4357/adfc72}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {133}, shortjournal = {The Astrophys. J.}, title = {Very late-time JWST and keck spectra of the oxygen-rich supernova 1995N}, volume = {991}, year = {2025}, }
• (2025). Properties of free-floating planets ejected through Planet–Planet scattering. ApJ, 991(2), 132. (www)

  @article{ , abstract = {Multiple studies show that planet–planet scattering plays a key role in the dynamical evolution of planetary systems. It can also contribute to the census of free-floating planets. In this work, we run an ensemble of N -body simulations and record the properties of ejected planets. Our simulations sample a wide range of orbital and physical parameters. We find that 40%–80% of planets are ejected, depending on the initial number in the system. Most ejections occur over ∼10 8 –10 9 yr. The mean excess velocity of ejected planets lies in the range 2–6 km s −1 relative to the host star, and strongly depends on the semimajor axis of the innermost planet. Regardless of initial location, all planets are equally likely to be ejected. Bound and ejected planets show distinct mass distributions, with bound planets being more massive. Increasing planetary radii reduces the ejection fraction due to higher collision rates. The properties of ejected planets do not strongly depend on initial spacing, though ejection timescales increase with separation. The ejection fraction is also largely insensitive to the distance from the host star used to define unbound status. Comparing our results with observed free-floating planet populations, we conclude that fewer than five Jovian-mass planets need to form per star to match observations—consistent with current constraints from both observations and planet formation models.}, archive = {J_ApJ}, author = {Hareesh Gautham Bhaskar and Hagai B. Perets}, doi = {10.3847/1538-4357/adf4e2}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {132}, shortjournal = {The Astrophys. J.}, title = {Properties of free-floating planets ejected through Planet–Planet scattering}, volume = {991}, year = {2025}, }
• (2025). Environmental effects in stellar mass gravitational-wave sources. i. expected fraction of signals with significant dephasing in the dynamical and active galactic nucleus channels. ApJ, 991(2), 131. (www)

  @article{ , abstract = {We present the first overview of the expected quantity of signals that will showcase significant gravitational-wave phase shifts caused by astrophysical environments, considering the upcoming A+ and A# LIGO/Virgo/KAGRA, Cosmic Explorer, and Einstein Telescope detectors. We construct and analyze two general families of dephasing prescriptions with extensions to eccentric sources, as well as collect five specific prescriptions for the fundamental smoking gun physical mechanisms at play in the dynamical and active galactic nucleus formation channel for stellar mass binary black holes: Roemer delays, tidal forces, and hydrodynamical interactions. We compute the expected fraction of signals containing astrophysical dephasing, as a function of environmental properties and based on observed distributions of binary parameters. We find that next generation detectors can expect to find environmental effects in hundreds of detected signals.}, archive = {J_ApJ}, author = {Lorenz Zwick and János Takátsy and Pankaj Saini and Kai Hendriks and Johan Samsing and Christopher Tiede and Connar Rowan and Alessandro A. Trani}, doi = {10.3847/1538-4357/adf6b8}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {131}, shortjournal = {The Astrophys. J.}, title = {Environmental effects in stellar mass gravitational-wave sources. i. expected fraction of signals with significant dephasing in the dynamical and active galactic nucleus channels}, volume = {991}, year = {2025}, }
• (2025). The compact object and innermost ejecta of SN 1987A. ApJ, 991(2), 130. (www)

  @article{ , abstract = {The first JWST observations of SN 1987A provided clear evidence that a compact object is ionizing the innermost ejecta. Here, we analyze a second epoch of JWST NIRSpec and MIRI/Medium-Resolution Spectrometer observations to better characterize the properties of this region, aided by a higher spectral resolving power for the new NIRSpec data. We confirm the presence of the previously identified narrow lines from the central region, i.e., ([Ar vi ] 4.5292 μ m, [Ar ii ] 6.9853 μ m, [S iv ] 10.5105 μ m, and [S iii ] 18.7130 μ m), and also identify similar components in [Ca v ] 4.1585 μ m, [Cl ii ] 14.3678 μ m, and possibly [Fe ii ] 1.6440 μ m. These lines are blueshifted by ∼−250 km s −1 , while the emission region is spatially unresolved and located southeast of the center. The offset and blueshift could imply a kick velocity of 510 ± 55 km s −1 for the neutron star. We also identify [Ca iv ] 3.2068 μ m near the center, but it is displaced to the north and has a redshift of ∼700 km s −1 . We find that scattering by dust in the ejecta with a typical grain size ∼0.3 μ m can explain the [Ca iv ] properties and the absence of other narrow lines at shorter wavelengths, while dust absorption is important at λ ≳ 8 μ m. Photoionization models for a pulsar wind nebula and a cooling neutron star are both compatible with the observations, with the exception of the [Fe ii ] feature. The two models primarily differ at short wavelengths, where new lines are expected to emerge over time as the optical depth of dust in the expanding ejecta decreases.}, archive = {J_ApJ}, author = {J. Larsson and C. Fransson and P. J. Kavanagh and B. Sargent and M. J. Barlow and M. Matsuura and C. Gall and R. D. Gehrz and N. Habel and A. S. Hirschauer and O. C. Jones and R. P. Kirshner and M. Meixner and S. Rosu and T. Temim}, doi = {10.3847/1538-4357/adf741}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {130}, shortjournal = {The Astrophys. J.}, title = {The compact object and innermost ejecta of SN 1987A}, volume = {991}, year = {2025}, }
• (2025). Spatial distribution of H2O+ ions in the inner coma of c/2014 q2 (Lovejoy). ApJ, 991(2), 129. (www)

  @article{ , abstract = {Neutral molecules that sublimate from cometary ices (mainly water at ∼1 au from the Sun) are ionized due to solar extreme-ultraviolet radiation and collisions with highly energetic electrons. The primary ionization product of water is H 2 O + , which is rapidly converted into H 3 O + through proton-transfer reaction with H 2 O in the inner coma. Ion-mass spectrometers on board spacecraft such as Giotto and Rosetta have measured H 2 O + ions in the inner coma, while emission bands of H 2 O + in the optical wavelength region can be observed from ground-based observatories. We present the spatial intensity distribution of the H 2 O + emission in comet C/2014 Q2 (Lovejoy), derived from high-resolution spectra taken on UT 2015 January 11. The observations covered a projected distance of ∼3000 km across the sky along the slit, with a spatial resolution of ∼200 km resulting from the atmospheric seeing. The observed H 2 O + profile scales as {\rho }^{-0.13} (where \rho is the projected distance from the nucleus), in contrast to the {\rho }^{-1} profile seen in sunlight reflected by dust grains. We modeled the intensity profile of H 2 O + using a steady-state, radially expanding coma model. Our results indicate that the proton-transfer reaction of H 2 O + with H 2 O dominates the loss process of H 2 O + in the inner coma. Assuming that H 2 O + is produced primarily by photoionization of H 2 O, the modeled intensity profile of H 2 O + remains constant, which is inconsistent with our observations. However, when an electron-impact ionization frequency inversely proportional to distance from the nucleus is assumed, the model successfully reproduces the observed profile.}, archive = {J_ApJ}, author = {Hideyo Kawakita and Yoshiharu Shinnaka and Hitomi Kobayashi}, doi = {10.3847/1538-4357/adf853}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {129}, shortjournal = {The Astrophys. J.}, title = {Spatial distribution of H2O+ ions in the inner coma of c/2014 q2 (Lovejoy)}, volume = {991}, year = {2025}, }
• (2025). JWST-MIRI observations of the irradiated chemistry in the inner disk cavity of GM aur. ApJ, 991(2), 128. (www)

  @article{ , abstract = {We present a spectroscopic analysis of the GM Aur disk using JWST MIRI-MRS, as part of the JWST Disk Infrared Spectral Chemistry Survey (JDISCS). The 1D spectrum exhibits faint dust continuum emission and is relatively poor in molecular gas compared to protoplanetary disks with no inner dust cavities. We identify fundamental CO emission, bright rotationally excited OH lines longward of 9 μ m, weak rotational H 2 O emission, the methyl cation CH {}_{3}^{+} , HCO + , and tentatively identify CO 2 . Otherwise, the spectrum is dominated by H 2 and atomic emission. We model the molecular spectra using slab models and retrieve excitation temperatures, column densities, and emitting areas in a Bayesian framework. The OH line fluxes are used to estimate the photodissociation rate of water. We find that 5.4 × 10 40 H 2 O molecules are photodestroyed every second, which suggests that the highest-energy OH lines trace a region near the 0.2 au dust cavity wall with an incident far-ultraviolet flux of G 0 ∼ 10 7 . The OH emission is compared to DALI models, which point toward a high incident flux of Ly α photons in the OH emitting region. We further use the H I lines to provide an independent estimate of the accretion luminosity and mass accretion rate, in agreement with prior measurements. A comparison with other cavity disks indicates that more evolved systems such as GM Aur may be less volatile rich and are characterized by brighter OH prompt emission and abundant molecular ions.}, archive = {J_ApJ}, author = {Carlos E. Romero-Mirza and Karin I. Öberg and Andrea Banzatti and Benoît Tabone and Joan Najita and Geoffrey A. Blake and Edwin A. Bergin and Sebastiaan Krijt and Charles J. Law and Feng Long and Jane Huang and David J. Wilner and Sean M. Andrews and Ian Czekala and Richard Teague and Yuri Aikawa and Jaehan Bae and Romane Le Gal and Felipe Alarcón and The JDISCS Collaboration}, doi = {10.3847/1538-4357/adf8db}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {128}, shortjournal = {The Astrophys. J.}, title = {JWST-MIRI observations of the irradiated chemistry in the inner disk cavity of GM aur}, volume = {991}, year = {2025}, }
• (2025). Solar and interplanetary determinants of long-term solar modulation of cosmic-ray intensity for median rigidities of 11–107 GV. ApJ, 991(2), 127. (www)

  @article{ , abstract = {We investigate the long-term modulation of cosmic-ray (CR) intensity across median rigidities from 11 to 107 GV using over four decades (1980–2023) of data from neutron monitors (NMs) and muon detectors (MDs). The analysis incorporates global NM stations and the Nagoya Multi-Directional Muon Telescope to evaluate the influence of key heliospheric parameters: interplanetary magnetic field (IMF) strength, heliospheric current sheet tilt angle (TA), and solar wind (SW) speed. Results reveal pronounced rigidity-dependent modulation patterns. Lower-rigidity NMs exhibit stronger sensitivity to heliospheric conditions, driven largely by IMF and TA, consistent with diffusion- and drift-dominated transport. In contrast, higher-rigidity MDs show reduced modulation amplitudes, with IMF remaining the dominant influence and SW gaining relative importance as drift effects diminish. These findings provide new insight into the energy-dependent roles of heliospheric drivers in CR modulation and offer a robust framework for advancing space weather prediction and heliospheric transport modeling.}, archive = {J_ApJ}, author = {K. Poopakun and W. Nuntiyakul and C. Kato and K. Munakata and M. Kozai and Y. Hayashi and D. Ruffolo and K. Iwai and H. Menjo and L. M. Zhai and M. L. Duldig}, doi = {10.3847/1538-4357/adfdd3}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {127}, shortjournal = {The Astrophys. J.}, title = {Solar and interplanetary determinants of long-term solar modulation of cosmic-ray intensity for median rigidities of 11–107 GV}, volume = {991}, year = {2025}, }
• (2025). Effect of nonuniform parallel magnetic field on the Kelvin–Helmholtz instability in the orion nebula. ApJ, 991(2), 126. (www)

  @article{ , abstract = {The surface rippled structures of Orion molecular cloud have been attributed to the Kelvin–Helmholtz (KH) instability, and the influence of magnetic field and pressure on the formation and evolution of these structures is one of the important issues that has been considered frequently in the dynamics of clouds. However, the effects of magnetic field inhomogeneity and compressibility variations are still underexplored. Here, the two-dimensional radiation magnetohydrodynamic simulations are performed to study the evolution of the KH instability in the Orion Nebula in the presence of a nonuniform magnetic field parallel to the flow direction. The results indicate that the rippled structures in the near Trapezium Cluster region are more pronounced. Also, the sound Mach number increases with decreasing gas pressure, enhancing the system compressibility and weakening the KH instability. And the position of the slow rarefaction layer, where the gas pressure is relatively weak, corresponds to that of the strong compression layer of the magnetic flux tube. Finally, it is found that the strong magnetic field gradient with small magnetic shear thickness between the H II region and the rippled region has a stabilizing effect on instability, which is a result of the increased magnetic field strength within the shear layer. Based on these results, it is preliminarily discussed that the magnetic field in the Orion Nebula is the key feedback process to regulate or stimulate the formation of stars, and the compressibility also affects the efficiency of the star formation.}, archive = {J_ApJ}, author = {Hang Peng and Fang Yu and Lai Wei and Zheng-Xiong Wang and Yue Liu}, doi = {10.3847/1538-4357/adfe6d}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {126}, shortjournal = {The Astrophys. J.}, title = {Effect of nonuniform parallel magnetic field on the Kelvin–Helmholtz instability in the orion nebula}, volume = {991}, year = {2025}, }
• (2025). Searching for accreting compact object binaries in SRG/eROSITA eRASS1. ApJ, 991(2), 125. (www)

  @article{ , abstract = {Compact object binaries with accreting white dwarfs, neutron stars, or black holes are crucial for understanding accretion physics. In this study, we identify accreting compact object binary candidates in the Spectrum–Roentgen–Gamma/eROSITA eRASS1 by combining their X-ray fluxes with Gaia photometry and Zwicky Transient Facility (ZTF) time-domain observations. Candidates are selected based on their location in the “X-ray Main Sequence,” a diagram incorporating their X-ray-to-optical flux ratios and optical colors, which suggest accretion-driven X-ray emission. We identify 22 candidates in the eRASS1 catalog using a three-step selection process: (1) cross-matching to a unique Gaia optical counterpart within a 10″ radius; (2) requiring X-ray-to-optical flux ratios exceeding the “X-ray Main Sequence”; and (3) detecting short-period variability in ZTF time-domain photometry. The resulting 22 candidates, including two previously confirmed compact object binaries, represent promising candidates for spectroscopic follow-up to confirm their accreting nature. Our results demonstrate the effectiveness of combining X-ray-to-optical flux ratios and optical colors jointly with time-domain photometry to uncover accreting compact object binaries. The approach is scalable and adaptable to future multiwavelength sky surveys, offering a promising path toward a more complete census of compact object binaries in the Galaxy.}, archive = {J_ApJ}, author = {Hao-Bin Liu and Wei-Min Gu and Yongqi Lu and Teng Liu and Jin-Zhong Liu}, doi = {10.3847/1538-4357/adfecd}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {125}, shortjournal = {The Astrophys. J.}, title = {Searching for accreting compact object binaries in SRG/eROSITA eRASS1}, volume = {991}, year = {2025}, }
• (2025). Mantis shrimp: Exploring photometric band utilization in computer vision networks for photometric redshift estimation. ApJ, 991(2), 124. (www)

  @article{ , abstract = {We present Mantis Shrimp , a multisurvey deep learning model for photometric redshift estimation that fuses ultraviolet (Galaxy Evolution Explorer), optical (PanSTARRS), and infrared (UnWISE) imagery. Machine learning is now an established approach for photometric redshift estimation, with generally acknowledged higher performance in areas with a high density of spectroscopically identified galaxies over template-based methods. Multiple works have shown that image-based convolutional neural networks can outperform tabular-based color/magnitude models. In comparison to tabular models, image models have additional design complexities: It is largely unknown how to fuse inputs from different instruments that have different resolutions or noise properties. The Mantis Shrimp model estimates the conditional density estimate of redshift using cutout images. The density estimates are well calibrated, and the point estimates perform well in the distribution of available spectroscopically confirmed galaxies with (bias = 1e-2), scatter (NMAD = 2.44e-2), and catastrophic outlier rate ( η >0.15 = 4.51%). We find that early-fusion approaches (e.g., resampling and stacking images from different instruments) match the performance of late-fusion approaches (e.g., concatenating latent space representations), so that the design choice ultimately is left to the user. Finally, we study how the model learns to use information across bands, finding evidence that our model successfully incorporates information from all surveys. The applicability of our model to the analysis of large populations of galaxies is limited by the speed and ease of downloading and preparing cutouts from external servers; however, our model could be useful in smaller studies such as in generating priors over redshift for stellar population synthesis.}, archive = {J_ApJ}, author = {Andrew W. Engel and Nell Byler and Adam Tsou and Gautham Narayan and Emmanuel Bonilla and Ian Smith}, doi = {10.3847/1538-4357/adf5b8}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {124}, shortjournal = {The Astrophys. J.}, title = {Mantis shrimp: Exploring photometric band utilization in computer vision networks for photometric redshift estimation}, volume = {991}, year = {2025}, }
• (2025). Exploring the frontiers of cosmic-ray physics: Perspectives on GRANDProto300 and the GRAND project. ApJ, 991(2), 123. (www)

  @article{ , abstract = {The Giant Radio Array for Neutrino Detection (GRAND) is an envisioned large-scale radio array designed to detect ultrahigh-energy cosmic rays (UHECRs, E > 100 PeV) and neutrinos. Employing cost-effective radio antennas distributed across vast areas, GRAND is optimized to observe the rare flux of ultrahigh-energy particles with high precision. The GRANDProto300 (GP300) pathfinder array, currently under deployment, targets the 10 16.5 –10 18 eV range and is anticipated to achieve approximately 15% energy resolution and 20 g cm −2 {X}_{{\rm{\max }}} precision. This level of precision enables accurate measurements of the fine structure of the energy spectrum, mean logarithmic mass ( \langle {\mathrm{ln}}\,A\rangle ), and proton flux within this energy range for GP300. After 5 yr of data collection, the sensitivity for detecting anisotropy could reach 5 × 10 −3 for energies below 10 17.1 eV. With its substantially larger effective area, GRAND extends these capabilities to the highest energies (∼10 20 eV), offering enhanced statistics and sensitivity for spectral, composition, and anisotropy measurements within 1 yr for UHECRs.}, archive = {J_ApJ}, author = {Kewen Zhang and Yi Zhang and Yi-Qing Guo}, doi = {10.3847/1538-4357/adfb6e}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {123}, shortjournal = {The Astrophys. J.}, title = {Exploring the frontiers of cosmic-ray physics: Perspectives on GRANDProto300 and the GRAND project}, volume = {991}, year = {2025}, }
• (2025). IBEX observations of elastic scattering of interstellar helium by solar wind particles. ApJ, 991(2), 122. (www)

  @article{ , abstract = {The IBEX-Lo instrument on the Interstellar Boundary Explorer (IBEX) mission observes primary and secondary interstellar helium in its four lowest energy steps. Observations of these helium populations have been analyzed and compared to simulations using the analytic full integration of neutrals model. A systematic difference is observed between the simulations and observations of secondary helium during solar cycle (SC) 24. We show that elastic scattering of primary helium by solar wind protons, which redistributes atoms from the core of the primary helium flux distribution, provides an explanation of the observed divergence from simulations. We test the validity of this explanation by showing that the elastic scattering also forms a halo in the wings of the primary helium distribution in the spin-angle plane. Correcting the simulation for the effects of elastic scattering requires an increase of the estimated density of primary helium, compared to previous estimates by Ulysses/GAS. The combined density of interstellar helium, derived from the previous studies, has been recalculated to be 0.0153 ± 0.0011. Based on our analysis of IBEX observations and χ 2 minimization of simulation data that include the effects of elastic scattering, any estimation of neutral interstellar helium density at 1 au by direct detection of the peak flux of neutral helium needs to be adjusted by ∼12%.}, archive = {J_ApJ}, author = {Hafijul Islam and Nathan A. Schwadron and Eberhard Möbius and Fatemeh Rahmanifard and Justyna M. Sokół and Andre Galli and David J. McComas and Peter Wurz and Stephen A. Fuselier and Kenneth W. Fairchild and David Heirtzler}, doi = {10.3847/1538-4357/adf4cc}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {122}, shortjournal = {The Astrophys. J.}, title = {IBEX observations of elastic scattering of interstellar helium by solar wind particles}, volume = {991}, year = {2025}, }
• (2025). Metal-enriched atmospheres in warm (Super- and sub-) neptunes induced by extreme atmospheric escape. ApJ, 991(1), 121. (www)

  @article{ , abstract = {Planet formation impacts exoplanet atmospheres by accreting metals in solid form, leading to atmospheric carbon-to-oxygen ratios (C/O) and sulfur-to-nitrogen ratios (S/N) that deviate from those of their host stars. Recent observations indicate differing metal abundances in planetary atmospheres compared to their stellar companions. However, these observations are biased toward mature planets, raising questions about whether these abundances result from formation or evolved over time. Another way to alter an atmosphere is through the escape of particles due to thermal heating. This study examines how billions of years of particle escape affect metal abundances. Using an adjusted stellar evolution code incorporating hydrodynamic escape, we model a warm ( T eq ≈ 1000 K) super-Neptune-type planet ( M ini = 26 M ⊕ ) orbiting a solar-type star. Our results show increased metal-to-hydrogen abundances of ∼50–70 × initial enrichment after 10 Gyr. We also see a 0.88 × decrease in C/O abundance and a 1.27 × increase in S/N abundance, which can affect the interpretation of planet formation parameters. We also simulate the evolving atmosphere using chemical kinetics and radiative transfer codes, finding substantial increases in SO 2 , CO 2 , and H 2 O abundances and a decrease in CH 4 abundance. These changes are easily observable in the IR wave band transmission spectrum. Our findings demonstrate that extreme escape of lighter particles significantly influences the evolution of warm Neptunes and complicates the interpretation of their observational data. This highlights the need to consider long-term atmospheric evolution in understanding exoplanet compositions.}, archive = {J_ApJ}, author = {Amy J. Louca and Yamila Miguel}, doi = {10.3847/1538-4357/add736}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {121}, shortjournal = {The Astrophys. J.}, title = {Metal-enriched atmospheres in warm (Super- and sub-) neptunes induced by extreme atmospheric escape}, volume = {991}, year = {2025}, }
• (2025). Toward robustness across cosmological simulation models IllustrisTNG, SIMBA, astrid, and swift-eagle. ApJ, 991(1), 120. (www)

  @article{ , abstract = {The rapid advancement of large-scale cosmological simulations has opened new avenues for cosmological and astrophysical research. However, the increasing diversity among cosmological simulation models presents a challenge to the robustness . In this work, we develop the Model-Insensitive ESTimator (M iest ), a machine that can robustly estimate the cosmological parameters, Ω m and σ 8 , from neural hydrogen maps of simulation models in the Cosmology and Astrophysics with MachinE Learning Simulations project—I llustris TNG, SIMBA , A strid , and S WIFT - E agle . An estimator is considered robust if it possesses a consistent predictive power across all simulations, including those used during the training phase. We train our machine using multiple simulation models and ensure that it only extracts common features between the models while disregarding the model-specific features. This allows us to develop a novel model that is capable of accurately estimating parameters across a range of simulation models, without being biased toward any particular model. Upon the investigation of the latent space—a set of summary statistics, we find that the implementation of robustness leads to the blending of latent variables across different models, demonstrating the removal of model-specific features. In comparison to a standard machine lacking robustness , the average performance of M iest on the unseen simulations during the training phase has been improved by ∼17% for Ω m and 38% for σ 8 . By using a machine learning approach that can extract robust , yet physical features, we hope to improve our understanding of galaxy formation and evolution in a (subgrid) model-insensitive manner, and ultimately, gain insight into the underlying physical processes responsible for robustness .}, archive = {J_ApJ}, author = {Yongseok Jo and Shy Genel and Anirvan Sengupta and Benjamin Wandelt and Rachel Somerville and Francisco Villaescusa-Navarro}, doi = {10.3847/1538-4357/adec78}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {120}, shortjournal = {The Astrophys. J.}, title = {Toward robustness across cosmological simulation models IllustrisTNG, SIMBA, astrid, and swift-eagle}, volume = {991}, year = {2025}, }
• (2025). A study of the dynamical structures in a dark matter halo using UMAP. ApJ, 991(1), 119. (www)

  @article{ , abstract = {We use a dimension reduction algorithm, Uniform Manifold Approximation and Projection (UMAP), to study dynamical structures inside a dark matter halo. We use a zoom-in simulation of a Milky Way mass dark matter halo and apply UMAP to the six-dimensional phase space in the dark matter field at z = 0. We find that particles in the field are mapped to distinct clusters in the lower dimensional space in a way that is closely related to their accretion history. The largest cluster in UMAP space does not contain the entire mass of the Milky Way virial region and neatly separates the older halo from the recently accreted matter. Particles within this cluster, which only comprise ∼70% of the Milky Way particles, have had several pericenter passages and are, therefore, likely to be phase mixed, becoming dynamically uniform. The infall region and recently accreted particles and substructure, even up to splashback, form distinct components in the lower dimensional space; additionally, higher angular momentum particles also take longer times to mix. Our work shows that the current state of the Milky Way halo retains historical information, particularly about the recent accretion history, and even a relatively old structure is not dynamically uniform. We also explore UMAP as a preprocessing step to find coherent subhalos in dark matter simulations.}, archive = {J_ApJ}, author = {Soorya Narayan and Susmita Adhikari}, doi = {10.3847/1538-4357/adec93}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {119}, shortjournal = {The Astrophys. J.}, title = {A study of the dynamical structures in a dark matter halo using UMAP}, volume = {991}, year = {2025}, }
• (2025). A systematic search for main-sequence dipper stars using the zwicky transient facility. ApJ, 991(1), 118. (www)

  @article{ , abstract = {Main-sequence dipper stars, characterized by irregular and often aperiodic luminosity dimming events, offer a unique opportunity to explore the variability of circumstellar material and its potential links to planet formation, debris disks, and broadly star–planet interactions. The advent of all-sky time-domain surveys has enabled the rapid discovery of these unique systems. We present the results of a large systematic search for main-sequence dipper stars, conducted across a sample of 63 million FGK main-sequence stars using data from Gaia eDR3 and the Zwicky Transient Facility survey. Using a novel light-curve scoring algorithm and a scalable workflow tailored for analyzing millions of light curves, we have identified 81 new dipper star candidates. Our sample reveals a diverse phenomenology of light-curve dimming shapes, such as skewed and symmetric dimmings with timescales spanning days to years, some of which closely resemble exaggerated versions of KIC 8462852. Our sample reveals no clear periodicity patterns in many of these dippers and no IR excess or variability. Using archival data collated for this study, we thoroughly investigate several classification scenarios and hypothesize that the mechanisms of such dimming events are either driven by circumstellar clumps or occultations by stellar/substellar companions with disks. Our study marks a significant step forward in understanding main-sequence dipper stars.}, archive = {J_ApJ}, author = {Anastasios Tzanidakis and James R. A. Davenport and Neven Caplar and Eric C. Bellm and Wilson Beebe and Doug Branton and Sandro Campos and Andrew J. Connolly and Melissa DeLucchi and Konstantin Malanchev and Sean McGuire}, doi = {10.3847/1538-4357/adf5bb}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {118}, shortjournal = {The Astrophys. J.}, title = {A systematic search for main-sequence dipper stars using the zwicky transient facility}, volume = {991}, year = {2025}, }
• (2025). Constraining active galactic nucleus jets with spectrum and core shift: The case of m87. ApJ, 991(1), 117. (www)

  @article{ , abstract = {We analytically model stationary and axisymmetric active galactic nucleus jets, assuming energy conservation along each magnetic flux tube. Using very long baseline interferometry (VLBI) observations and published general relativistic magnetohydrodynamic simulations, we constrain the evolution of the bulk Lorentz factor, the magnetization parameter, and the magnetic field strength along the jet. We then infer the electron density, emission coefficient, and absorption coefficient at each point, and integrate the radiative transfer equation to compute the spectral energy distribution (SED) and the core shift of the synchrotron emission from the relativistic jet. Applying the method to the M87 jet, we find that the hot plasmas are injected at the altitude of seven Schwarzschild radii from the black hole (BH), that the M87 jet is likely composed of a pair plasma, and that the jet flowline geometry is quasi-parabolic as reported at much greater distances. Fitting the nonthermal fraction of the leptonic jet as a function of the position, we also find that most of the radio photons are emitted within 1000 Schwarzschild radii from the BH. Although hadronic jets do not reproduce all the VLBI observations consistently in our model, we also discuss that their heavy mass allows for a stronger magnetic field within the observational constraints, leading to an inverted SED in submillimeter wavelengths by the thermal emission from the jet base. It is therefore implied that contemporaneous observations of the M87 jet with Atacama Large Millimeter/submillimeter Array and VLBI could discriminate the jet composition and its collimation within the central 100 Schwarzschild radii.}, archive = {J_ApJ}, author = {Kouichi Hirotani and Hsien Shang and Ruben Krasnopolsky and Satoki Matsushita and Britton Jeter and Keiichi Asada}, doi = {10.3847/1538-4357/adf71f}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {117}, shortjournal = {The Astrophys. J.}, title = {Constraining active galactic nucleus jets with spectrum and core shift: The case of m87}, volume = {991}, year = {2025}, }
• (2025). BASS. LII. the prevalence of double-peaked broad lines at low accretion rates among hard X-ray selected active galactic nuclei. ApJ, 991(1), 116. (www)

  @article{ , abstract = {A fraction of active galactic nuclei (AGN) have double-peaked H α , H β, and Mg II broad lines attributed to emission from rotating gas in the accretion disk. Using optical spectroscopy of a flux-limited sample of AGN selected via ultrahard X-rays from the BAT AGN Spectroscopic Survey (BASS), we systematically identify 71 double-peaked emitters (DPEs) among 343 broad-line AGN with redshifts 0.004 < z < 0.297 and X-ray luminosities of 40\lt \,{\mathrm{log}}\,{L}_{2-10\,{\rm{KeV}}\,} (erg s −1 ) < 45.7, and provide their best-fit accretion disk parameters. We find that ∼21% of X-ray-selected broad-line AGN are DPEs, consistent with rates previously reported for z < 0.2 broad-line AGN selected for strong optical variability in the Zwicky Transient Facility. 11 of 71 DPEs (15%) exhibited a single-peaked Gaussian component to the broad line profile in addition to the double-peaked disk profile. In this sample, DPEs have intrinsically higher masses by ∼0.4 dex and lower Eddington ratios by ∼0.3 dex than other broad-line AGN, and have a preference for elliptical host galaxies, higher X-ray luminosities, and higher [O i ] λ 6302 to narrow H α flux ratios than other broad-line AGN. We find that DPEs are not segregated from non-DPE broad-line AGN in the L bol versus M BH relation or their X-ray to radio luminosity ratios, and do not show a preference for intermediate Seyfert types over Seyfert 1s. We do not find differences in a wide range of multiwavelength properties when comparing DPEs to non-DPE broad-line AGN, including optical and mid-IR variability levels, Wide-field Infrared Survey Explorer colors, α ox , the column density of neutral obscuring material N H , and the rate of changing-look events. We discuss the two populations in the context of multicomponent disk-wind models of the AGN broad-line region and consider how unrecognized contributions of disk emission to the broad lines may introduce biases in “virial” supermassive black hole mass estimates, with consequences for the inferred M BH – M * relation.}, archive = {J_ApJ}, author = {Charlotte Ward and Michael J. Koss and Michael Eracleous and Benny Trakhtenbrot and Franz E. Bauer and Turgay Caglar and Fiona Harrison and Arghajit Jana and Darshan Kakkad and Macon Magno and Ignacio del Moral-Castro and Richard Mushotzky and Kyuseok Oh and Alessandro Peca and Meredith C. Powell and Claudio Ricci and Alejandra Rojas and Krista Lynne Smith and Daniel Stern and Ezequiel Treister and C. Megan Urry}, doi = {10.3847/1538-4357/adfa25}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {116}, shortjournal = {The Astrophys. J.}, title = {BASS. LII. the prevalence of double-peaked broad lines at low accretion rates among hard X-ray selected active galactic nuclei}, volume = {991}, year = {2025}, }
• (2025). EP241021a: A catastrophic Collapse/Merger of compact star binary leading to the formation of a remnant millisecond magnetar?. ApJ, 991(1), 115. (www)

  @article{ , abstract = {Observations of fast X-ray transients (FXRTs) with the Einstein Probe have successfully led to the discovery of some unusual extragalactic optical transients. EP241021a is a newly discovered FXRT that was featured by a significant bump at around 10 days in both optical and X-ray bands. This timescale and the exceptionally high peak bolometric luminosity up to ∼10 44 erg s −1 of the optical bump make it somewhat similar to fast blue optical transients but still distinctive from them by its relatively red color. We then suggest that the multiwavelength bump of EP241021a could represent an explosion-type transient, while the underlying power-law decaying component of the optical and X-ray emission as well as the total radio emission are produced by a moderately relativistic jet. By fitting the observed multiwavelength light curves, it is found that the explosion ejecta that produce the thermal optical emission can have a mass of ∼0.03 M ⊙ , an expanding velocity of ∼0.25 c , and an optical opacity of ∼12 cm 2 g −1 , which was continuously powered by a rapidly rotating and highly magnetized neutron star (NS; i.e., a magnetar). In addition to heating the explosion ejecta, the magnetar also provided the dominant contribution to the observed X-ray rebrightening through the nonthermal emission of its wind. These properties suggest that the explosion may result from a catastrophic collapse/merger of a compact star system, which led to the formation of a millisecond magnetar, and the possible progenitor could be an accreting white dwarf (WD) or a binary consisting of a double WD, a double NS, or a WD and an NS.}, archive = {J_ApJ}, author = {Guang-Lei Wu and Yun-Wei Yu and Liang-Duan Liu and Zi-Gao Dai and Wei-Hua Lei and Xue-Feng Wu and Dong Xu and Bing Zhang and Jin-Ping Zhu and Yuan-Chuan Zou}, doi = {10.3847/1538-4357/adfbf0}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {115}, shortjournal = {The Astrophys. J.}, title = {EP241021a: A catastrophic Collapse/Merger of compact star binary leading to the formation of a remnant millisecond magnetar?}, volume = {991}, year = {2025}, }
• (2025). Magnetic field characteristics of moving magnetic features during the sunspot decay from the whole sunspot to pore. ApJ, 991(1), 114. (www)

  @article{ , abstract = {To understand the relationship between moving magnetic features (MMFs) and the decay of the sunspot, we studied the complete decays of four α -type sunspots based on data from the Solar Dynamics Observatory/Helioseismic and Magnetic Imager, focusing on the magnetic properties of same-polarity MMFs at the moment they detach from the sunspots. The main results are as follows: (1) The area and horizontal velocity of MMFs mainly range from 0.4 to 2 MSH and 0.2 to 1.7 km s −1 , with typical values of 0.65 MSH and 0.6 km s −1 , respectively. The dominant ranges for B , B t , B z , and γ are 200–400 G, 75–350 G, 153–297 G, and 20°–60°, respectively. (2) Comparing the pre-pore (the stage before the sunspot transforms into the pore) and pore (after the transformation) stages, the area, horizontal velocity, and B z show similar distribution ranges, while the mean values and ranges of B , B t , and γ decrease significantly. (3) In the pre-pore stage, MMFs predominantly manifest as horizontal MMFs (MMFs that have a horizontal magnetic field (45° < γ < 90°)), whereas in the pore stage, most of them are observed as vertical MMFs (MMFs that have a vertical magnetic field (0° < γ ≤ 45°)). These findings provide observational evidence for the turbulent erosion model of the sunspot decay; the mean vertical magnetic field may be an important parameter for the detachment of MMFs from the sunspots.}, archive = {J_ApJ}, author = {Yang Peng and Zhike Xue and Chunlan Jin and Jihong Liu and Dean Webb}, doi = {10.3847/1538-4357/adfccf}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {114}, shortjournal = {The Astrophys. J.}, title = {Magnetic field characteristics of moving magnetic features during the sunspot decay from the whole sunspot to pore}, volume = {991}, year = {2025}, }
• (2025). Effects of dissipation physics on high-frequency quasiperiodic oscillations in black hole X-ray binaries. ApJ, 991(1), 113. (www)

  @article{ , abstract = {We numerically investigate the effects of black hole spin and local dissipation profiles on high-frequency quasiperiodic oscillation (HFQPO) observed in black hole X-ray binaries (BHXBs). Our HFQPO power spectra arise from self-consistent calculations that do not rely on ad hoc assumptions regarding disk geometry. Our models combine radiative transfer and disk vertical structure equations with input motivated by first-principles three-dimensional simulations. We found that HFQPO power spectra may be sensitive to the spatial distribution of dissipation rates, while the quality factors are more sensitive to black hole spin. We discuss the observational implications of our results in the context of steep power-law spectra from BHXBs that are seen together with HFQPOs, and how quasiperiodic oscillation properties may be indicators of the underlying physical oscillations.}, archive = {J_ApJ}, author = {Theodore Dezen and Sergio Gomez and Kathryn Anawalt}, doi = {10.3847/1538-4357/adfd5d}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {113}, shortjournal = {The Astrophys. J.}, title = {Effects of dissipation physics on high-frequency quasiperiodic oscillations in black hole X-ray binaries}, volume = {991}, year = {2025}, }
• (2025). Palladium and silver abundances in extremely metal-poor stars. ApJ, 991(1), 112. (www)

  @article{ , abstract = {Based on the high-resolution and high signal-to-noise ratio near-ultraviolet spectra from the ESO VLT 8.2 m Kueyen telescope, we investigate the abundances of palladium (Pd) and silver (Ag) in a sample of 27 extreme metal-poor stars. The metallicity range of our sample stars is from ∼−2.2 to ∼−3.66 dex, and they are crucial for understanding the formation and evolution of weak r -process elements in our early Galaxy. The stellar atmospheric parameters, including effective temperature ( T eff ), surface gravity (log g ), metallicity ([Fe/H]), and microturbulence ( ξ t ) are derived using the spectroscopic method, and the nonlocal thermodynamic equilibrium effects for both Fe i and Fe ii lines have been considered when determining the iron abundance. Our results show that both [Pd/Fe] and [Ag/Fe] exhibit flat trends with metallicities between −0.7 and −3.0 dex, with an increasing scatter at lower metallicities. This study also finds a clear correlation between [Ag/H] and [Pd/H], indicating that both elements likely share a similar nucleosynthetic origin.}, archive = {J_ApJ}, author = {Panpan Huang and Zeming Zhou and Wenyuan Cui and Jianrong Shi and Miao Tian and Junbo Zhang and Xiaolei Li}, doi = {10.3847/1538-4357/adfedc}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {112}, shortjournal = {The Astrophys. J.}, title = {Palladium and silver abundances in extremely metal-poor stars}, volume = {991}, year = {2025}, }
• (2025). Orbital period changes in recurrent nova t corona borealis prove that it is not a type ia supernovae progenitor. ApJ, 991(1), 111. (www)

  @article{ , abstract = {T Corona Borealis (T CrB) is a recurrent nova and a symbiotic star that is commonly highlighted as the best case for being a progenitor of a Type Ia supernova (SN Ia) within the framework of single-degenerate models. This exemplar can be tested by measuring whether the white dwarf (WD) mass ( M WD ) is increasing over each eruption cycle. This is a balance between the mass ejected during each nova event ( M ejecta ) and the mass accreted onto the WD between the nova events ( M accreted ). I have used all 206 radial velocities from 1946 to 2024 to measure the orbital period just after the 1946 eruption, which is P post = 227.6043 days, while the steady orbital period change ( \dot{P} ) is (−3.1 ± 1.6) × 10 −6 . I have used my full 213,730 magnitude B and V light curve from 1842 to 2025 to measure the times of maximum brightness in the ellipsoidal modulations to construct the O − C from 1866 to 1946. I fit the broken parabola shape to find the orbital period immediately before the 1946 eruption, which is {P}_{{\rm{pre}}} = 227.4586 days. The orbital period changed by Δ P = +0.146 ± 0.019 days. With Kepler’s Law, conservation of angular momentum, and the well-measured binary properties, the ejecta mass in 1946 is 0.00074 ± 0.00009 M ⊙ . M accreted is reliably measured to be 1.38 × 10 −6 M ⊙ from the accretion luminosity. M ejecta is larger than M accreted by 540×, so M WD is decreasing every eruption cycle. T CrB can never become an SN Ia.}, archive = {J_ApJ}, author = {Bradley E. Schaefer}, doi = {10.3847/1538-4357/adfa16}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {111}, shortjournal = {The Astrophys. J.}, title = {Orbital period changes in recurrent nova t corona borealis prove that it is not a type ia supernovae progenitor}, volume = {991}, year = {2025}, }
• (2025). Orbital period changes of recurrent nova u scorpii demonstrate that mejecta = 26 × maccreted, so u sco is not a type ia supernova progenitor. ApJ, 991(1), 110. (www)

  @article{ , abstract = {Recurrent nova U Scorpii (U Sco) is one of the prototypes for a Type Ia supernova progenitor. The logic is that the white dwarf is near the Chandrasekhar mass and gas is accumulating onto its surface at a near-maximal accretion rate, so it will soon increase its mass to the supernova trigger. But the white dwarf loses mass every nova eruption, so the issue is balancing the mass ejected ( M ejecta ) against the mass accreted between eruptions ( M accreted ). Measuring M accreted can be done in several ways to usable accuracy. But the old methods for measuring M ejecta (involving the flux in hydrogen emission lines) all have real error bars of 2–3 orders of magnitude. The only solution is to measure the change of the orbital period across the nova eruption (Δ P ). But this solution requires a vast photometric program of eclipse timings stretching decades. For U Sco, a program started in 1989, now reaches its culmination with measures of Δ P for the eruptions of 1999, 2010, 2016, and 2022. This paper reports on 52 new eclipse times (for a total of 218 eclipses from 1945 to 2025), plus a new theory result allowing for the confident calculation of M ejecta from Δ P . The four eruptions ejected a total of (103 ± 14) × 10 −6 M ⊙ , while the white dwarf accreted 4 × 10 −6 M ⊙ over the four previous eruption cycles. With M ejecta = 26 × M accreted , the U Sco white dwarf is losing large masses each eruption cycle, so U Sco can never produce a Type Ia supernova.}, archive = {J_ApJ}, author = {Bradley E. Schaefer and Gordon Myers}, doi = {10.3847/1538-4357/adf961}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {110}, shortjournal = {The Astrophys. J.}, title = {Orbital period changes of recurrent nova u scorpii demonstrate that mejecta = 26 × maccreted, so u sco is not a type ia supernova progenitor}, volume = {991}, year = {2025}, }
• (2025). Exploring the masses of the two most distant gravitational lensing clusters at cosmic noon. ApJ, 991(1), 109. (www)

  @article{ , abstract = {Observations over the past decade have shown that galaxy clusters undergo the most transformative changes during the z = 1.5–2 epoch. However, challenges such as low lensing efficiency, high shape measurement uncertainty, and a scarcity of background galaxies have prevented us from characterizing their masses with weak gravitational lensing (WL) beyond redshift z ∼ 1.75. In this paper, we report the successful WL detection of JKCS 041 and XLSSC 122 at z = 1.80 and z = 1.98, respectively, utilizing deep infrared imaging data from the Hubble Space Telescope with careful removal of instrumental effects. These are the most distant clusters ever measured through WL. The mass peaks of JKCS 041 and XLSSC 122, which coincide with the X-ray peak positions of the respective clusters, are detected at the ∼3.7 σ and ∼3.2 σ levels, respectively. Assuming a single spherical Navarro–Frenk–White profile, we estimate that JKCS 041 has a virial mass of M 200 c = (5.4 ± 1.6) × 10 14 M ⊙ , while the mass of XLSSC 122 is determined to be M 200 c = (3.3 ± 1.8) × 10 14 M ⊙ . These WL masses are consistent with the estimates inferred from their X-ray observations. We conclude that although the probability of finding such massive clusters at their redshifts is certainly low, their masses can still be accommodated within the current ΛCDM paradigm.}, archive = {J_ApJ}, author = {Jinhyub Kim and M. James Jee and Stefano Andreon and Tony Mroczkowski and Lance Miller and Joshiwa van Marrewijk and Hye Gyeong Khim}, doi = {10.3847/1538-4357/adf29e}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {109}, shortjournal = {The Astrophys. J.}, title = {Exploring the masses of the two most distant gravitational lensing clusters at cosmic noon}, volume = {991}, year = {2025}, }
• (2025). Rigorous analytic solution to the gravitational-wave overlapping event rates. ApJ, 991(1), 108. (www)

  @article{ , abstract = {In the era of the next-generation gravitational-wave detectors, signal overlaps will become prevalent due to the high detection rate and long signal duration, posing significant challenges to data analysis. While effective algorithms are being developed, there still lacks an integrated understanding of the statistical properties for the population of overlapping compact binary coalescence signals. For the first time, in order to aid rapid and robust estimation, we rigorously derive and establish analytical expressions for the expectation and variance for the number of overlapping events. This framework is highly extensible, allowing analytical calculation for more complicated scenarios, such as multi-signal overlaps, overlaps between different types of sources, and source-dependent thresholds. We also mathematically prove that the time difference between events in a single observation run is described by the beta distribution, offering an analytical prior reference for Bayesian analysis.}, archive = {J_ApJ}, author = {Ziming Wang and Zexin Hu and Lijing Shao}, doi = {10.3847/1538-4357/adfa1d}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {108}, shortjournal = {The Astrophys. J.}, title = {Rigorous analytic solution to the gravitational-wave overlapping event rates}, volume = {991}, year = {2025}, }
• (2025). Gas pressure driven screening forces and pebble aggregation: A pathway for growth in planet formation. ApJ, 991(1), 107. (www)

  @article{ , abstract = {The formation of planetesimals from centimeter-sized pebbles in protoplanetary disks faces significant barriers, including fragmentation and radial drift. We identify a previously unaccounted screening force, arising from mutual shielding of thermal gas particles between pebbles when their separation falls below the gas mean free path. This force facilitates pebble binding, overcoming key growth barriers under turbulent disk conditions. Unlike conventional mechanisms, screening forces operate independently of surface adhesion and complement streaming instability and pressure traps by enhancing aggregation in high-density regions. Our analysis predicts that screening interactions are most effective in the middle disk regions (∼0.3 to a few astronomical units), consistent with Atacama Large Millimeter/submillimeter Array observations (e.g., TW Hya) of enhanced dust concentrations. Furthermore, we find that screening-induced pebble growth from centimeter to kilometer scales can occur on timescales significantly shorter than the disk lifetime (∼10 5 yr). Importantly, this growth naturally terminates when particles smaller than the local gas mean free path are depleted, thereby avoiding runaway accretion. Beyond planetary science, the screening forces have potential implications for high-energy astrophysics, dusty plasmas, confined particle suspensions, and other relevant areas, suggesting a broader fundamental significance.}, archive = {J_ApJ}, author = {Mukesh Kumar Vyas}, doi = {10.3847/1538-4357/adfa9a}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {107}, shortjournal = {The Astrophys. J.}, title = {Gas pressure driven screening forces and pebble aggregation: A pathway for growth in planet formation}, volume = {991}, year = {2025}, }
• (2025). Outer solar system spacecraft to probe the μHz gravitational-wave frontier. ApJ, 991(1), 106. (www)

  @article{ , abstract = {The microhertz frequency band of gravitational waves probes the merger of supermassive black holes, as well as many other gravitational-wave phenomena. However, space-interferometry methods that use test masses would require further development of test-mass isolation systems to detect anticipated astrophysical events. We propose an approach that avoids onboard inertial test masses by situating spacecraft in the low-acceleration environment of the outer solar system. We show that, for Earth–spacecraft and interspacecraft distances of ≳10 au, the accelerations on the spacecraft would be sufficiently small to potentially achieve gravitational-wave sensitivities determined by stochastic gravitational-wave backgrounds. We further argue, for arm lengths of 10−30 au and ∼10 W transmissions, that stable phase locks could be achieved with 20 cm mirrors or 5 m radio dishes. We discuss designs that send both laser beams and radio waves between the spacecraft, finding that, despite the ∼ 10 4 × longer wavelengths, even a design with radio transmissions could reach stochastic background-limited sensitivities at ≲0.3 × 10 −4 Hz. Operating in the radio significantly reduces many spacecraft design tolerances. Our baseline concepts require two arms to do interferometry. However, if one spacecraft carries a clock with Allan deviations at 10 4 s of 10 −17 , a comparable sensitivity could be achieved with a single arm. Finally, we discuss the feasibility of achieving similar gravitational-wave sensitivities in a “Doppler tracking” configuration where the single arm is anchored to Earth.}, archive = {J_ApJ}, author = {Matthew McQuinn and Casey McGrath}, doi = {10.3847/1538-4357/adf5a2}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {106}, shortjournal = {The Astrophys. J.}, title = {Outer solar system spacecraft to probe the μHz gravitational-wave frontier}, volume = {991}, year = {2025}, }
• (2025). Validation and calibration of semianalytical models for the event horizon telescope observations of sagittarius a*. ApJ, 991(1), 105. (www)

  @article{ , abstract = {The Event Horizon Telescope (EHT) enables the exploration of black hole accretion flows at event-horizon scales. Fitting ray-traced physical models to EHT observations requires the generation of synthetic images, a task that is computationally demanding. This study leverages ALINet , a generative machine learning model, to efficiently produce radiatively inefficient accretion flow (RIAF) images as a function of the specified physical parameters. ALINet has previously been shown to be able to interpolate black hole images and their associated physical parameters after training on a computationally tractable set of library images. We utilize this model to estimate the uncertainty introduced by a number of anticipated unmodeled physical effects, including interstellar scattering and intrinsic source variability. We then use this to calibrate physical parameter estimates and their associated uncertainties from RIAF model fits to mock EHT data via a library of general relativistic magnetohydrodynamics models.}, archive = {J_ApJ}, author = {Ali SaraerToosi and Avery E. Broderick}, doi = {10.3847/1538-4357/adf6b7}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {105}, shortjournal = {The Astrophys. J.}, title = {Validation and calibration of semianalytical models for the event horizon telescope observations of sagittarius a*}, volume = {991}, year = {2025}, }
• (2025). Exploring SEP transport in widespread events with different heliospheric current sheet models. ApJ, 991(1), 104. (www)

  @article{ , abstract = {Understanding solar energetic particle transport in wide-longitude events remains a significant question in heliophysics. By utilizing the increasing number of available observers at various heliographic distances and longitudes, such as Parker Solar Probe and Solar Orbiter, we are able to further our understanding of these widespread events. This study presents 3D test particle modeling of three widespread events during the Parker era, each detected by at least four observers. The role of the heliospheric current sheet (HCS) in transporting particles to the wide longitudes observed in these events is evaluated. A newly updated and more sophisticated HCS model is used, incorporating three different configurations derived from the Wilcox Solar Observatory, Air Force Data Assimilative Photospheric Flux Transport, and Solar Dynamics Observatory/Helioseismic and Magnetic Imager (HMI) data (via Predictive Science, PSI) for each event. The modeled proton flux profiles at each observer location are compared against energetic proton measurements for each HCS configuration. We find that inclusion of the HCS is essential to reproduce both the wide longitudinal spread of particles and the observed flux profiles in all three events. For events with longitudinal separations exceeding 100°, the most intense fluxes, both observed and modeled, are associated with observers located nearest to the HCS. This is observed for the 2023 March 13 event, where two observers were located closer in longitude and radial distance than other observers to the source region, yet observed no solar energetic particle signatures due to their lack of proximity to the HCS. Among the three configurations, the HMI-PSI-derived HCS consistently yields the best agreement between observed and modeled flux profiles.}, archive = {J_ApJ}, author = {C. O. G. Waterfall and G. A. de Nolfo and A. Hutchinson and D. da Silva and S. Wallace and S. Dalla and J. G. Mitchell}, doi = {10.3847/1538-4357/adf8d9}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {104}, shortjournal = {The Astrophys. J.}, title = {Exploring SEP transport in widespread events with different heliospheric current sheet models}, volume = {991}, year = {2025}, }
• (2025). Quasar spectral energy distributions in the rest-frame extreme ultraviolet: Hubble-COS spectra of two ultraluminous quasars. ApJ, 991(1), 103. (www)

  @article{ , abstract = {Using the Cosmic Origins Spectrograph (COS) on board the Hubble Space Telescope with both far-UV (FUV) and near-UV (NUV) gratings, we measure the ionizing spectra of two bright, intermediate-redshift quasars in their rest-frame extreme ultraviolet (EUV). The availability of both NUV and FUV spectra allows us to define the quasar continuum and correct for strong Lyman-limit systems (LLSs) that fall in the gap between the FUV and optical. Each active galactic nucleus (AGN) has a prominent LLS, but the flux recovery shortward of their Lyman edges allows us to fit and restore the true AGN continuum. In the EUV (450–912 Å), these AGN have flux distributions, {F}_{\nu }\propto {\nu }^{-{\alpha }_{\nu }} , with spectral indices α ν = 1.11 ± 0.22 (SBS 1010+535, z AGN = 1.5086) and α ν = 0.98 ± 0.22 (HS 0747+4259, z AGN = 1.9006), both considerably harder than the mean index, α ν = 1.41 ± 0.15, in a COS composite spectrum of 159 UV-bright AGN. These two AGN are outliers in the index distribution, perhaps resulting from their extremely high UV luminosity (0.4-0.9) × 10 48 erg s −1 ), estimated black-hole masses (0.5–1) × 10 10 M ⊙ , and effects on the inner accretion disk and Comptonized winds.}, archive = {J_ApJ}, author = {J. Michael Shull and Rongmon Bordoloi and Charles Danforth}, doi = {10.3847/1538-4357/adfb5f}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {103}, shortjournal = {The Astrophys. J.}, title = {Quasar spectral energy distributions in the rest-frame extreme ultraviolet: Hubble-COS spectra of two ultraluminous quasars}, volume = {991}, year = {2025}, }
• (2025). A linearly polarized merger shock down to 550 MHz: A uGMRT study of the merging cluster a746. ApJ, 991(1), 102. (www)

  @article{ , abstract = {Radio relics, arc-like polarized sources with highly aligned magnetic fields, are typically found on the outskirts of merging galaxy clusters. The magnetoionic media responsible for the significant coherence observed in radio relics remain poorly understood. Low-frequency measurements of radio relics are essential for constraining depolarization models, which provide crucial insights into the magnetic field distribution. However, these measurements are challenging due to the emission properties and interferometer systematics. We have detected polarization signals from the northwest radio relic in A746 at 650 MHz with the upgraded Giant Meterwave Radio Telescope, marking the first-ever detection of polarization from radio relics below 1 GHz. At this frequency, the average rotation-measure-corrected magnetic fields align well with shock radio emission, typical of radio relics. The fractional polarization at 650 MHz is ∼18% ± 4%. Our results indicate that a single internal depolarization model cannot explain the observed depolarization spectra, suggesting a nonuniform magnetic field distribution or complex contribution of different polarized regions in the radio relic. Our detection of polarization signals at 650 MHz reveals critical insights into radio relic magnetic field structures, offering a low-frequency approach to understanding intracluster medium magnetic fields in merging galaxy clusters.}, archive = {J_ApJ}, author = {Arpan Pal and Ruta Kale and Reinout J. van Weeren}, doi = {10.3847/1538-4357/ae003f}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {102}, shortjournal = {The Astrophys. J.}, title = {A linearly polarized merger shock down to 550 MHz: A uGMRT study of the merging cluster a746}, volume = {991}, year = {2025}, }
• (2025). The DECam MAGIC survey: Spectroscopic follow-up of the most metal-poor stars in the distant milky way halo*. ApJ, 991(1), 101. (www)

  @article{ , abstract = {In this work, we present high-resolution spectroscopic observations for six metal-poor stars with [Fe/H] < –3 (including one with [Fe/H] < –4), selected using narrowband Ca ii HK photometry from the DECam MAGIC Survey. The spectroscopic data confirm the accuracy of the photometric metallicities and allow for the determination of chemical abundances for 16 elements, from carbon to barium. The program stars have chemical abundances consistent with the [Fe/H] < –3 range. A kinematic/dynamical analysis suggests that all program stars belong to the distant Milky Way halo population (heliocentric distances 35 < d helio /kpc ≲ 55), including three with high-energy orbits that might have been associated with the Magellanic system and one, J0026−5445, having parameters consistent with being a member of the Sagittarius stream. The remaining two stars show kinematics consistent with the Gaia-Sausage/Enceladus dwarf galaxy merger. J0433−5548, with [Fe/H] = –4.12, is a carbon-enhanced ultra metal-poor star, with [C/Fe] = +1.73. This star is believed to be a bona fide second-generation star, and its chemical abundance pattern was compared with yields from metal-free supernova models. Results suggest that J0433−5548 could have been formed from a gas cloud enriched by a single supernova explosion from an ∼11 M ⊙ star in the early Universe. The successful identification of such objects demonstrates the reliability of photometric metallicity estimates, which can be used for target selection and statistical studies of faint targets in the Milky Way and its satellite population. These discoveries illustrate the power of measuring chemical abundances of metal-poor Milky Way halo stars to learn more about early galaxy formation and evolution.}, archive = {J_ApJ}, author = {Vinicius M. Placco and Guilherme Limberg and Anirudh Chiti and Deepthi S. Prabhu and Alexander P. Ji and Fabrícia O. Barbosa and William Cerny and Andrew B. Pace and Guy S. Stringfellow and David J. Sand and Clara E. Martínez-Vázquez and Alexander H. Riley and Silvia Rossi and Noelia E. D. Noël and A. Katherina Vivas and Gustavo E. Medina and Alex Drlica-Wagner and Joanna D. Sakowska and Burçin Mutlu-Pakdil and Pol Massana and Julio A. Carballo-Bello and Yumi Choi and Denija Crnojević and Chin Yi Tan and (MAGIC & DELVE Collaborations)}, doi = {10.3847/1538-4357/adf846}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {101}, shortjournal = {The Astrophys. J.}, title = {The DECam MAGIC survey: Spectroscopic follow-up of the most metal-poor stars in the distant milky way halo*}, volume = {991}, year = {2025}, }
• (2025). Scattering of continuously injected pickup ions of oblique pickup angles in the outer heliosheath. ApJ, 991(1), 100. (www)

  @article{ , abstract = {Pitch angle scattering of pickup ions (PUIs) in the outer heliosheath is studied using two-dimensional hybrid simulations, with the PUIs continuously injected at specified injection rates and pickup angles. The simulations reveal the growth of quasiparallel-propagating waves, quasi-antiparallel-propagating waves, and the oblique mirror mode. The excited waves scatter the PUIs and can reverse their parallel velocities with respect to the background magnetic field. The scattering time, defined as the time when the squared standard deviation of the pitch angles of the PUIs approaches thresholds of 0.2 or 0.4, increases as the PUI injection rate decreases, approximately following a power law. The scattering time estimated for a realistic injection rate in the outer heliosheath is about 0.5 yr at a 45° pickup angle. This scattering time is shorter than the average charge exchange time of about 2 yr for the PUIs to be converted into energetic neutral atoms (ENAs). This result conflicts with the spatial retention scenario of the secondary ENA mechanism, which assumes weak (or incomplete) scattering of PUIs in the off-ribbon directions to explain the ENA ribbon discovered by the Interstellar Boundary Explorer.}, archive = {J_ApJ}, author = {Ding Sheng and Kaijun Liu and Vladimir Florinski and Xiaocheng Guo}, doi = {10.3847/1538-4357/adfa86}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {100}, shortjournal = {The Astrophys. J.}, title = {Scattering of continuously injected pickup ions of oblique pickup angles in the outer heliosheath}, volume = {991}, year = {2025}, }
• (2025). Line-of-sight bias in dark matter inferences from galaxy cluster mergers. ApJ, 991(1), 99. (www)

  @article{ , abstract = {In collisions of galaxy clusters, the lack of displacement between dark matter and galaxies suggests that the dark matter scattering depth is small. This yields an upper limit on the dark matter cross section if the dark matter column density is known. We investigate a bias in such constraints: the measured column density (along the line of sight, using gravitational lensing) is lower than that experienced by a dark matter particle, as follows. Dark matter halos are triaxial and generally collide along their major axes, yielding a high scattering column density—but the merger is obvious only to observers whose line of sight is nearly perpendicular to that axis, yielding a low observed column density. We trace lines of sight through merging halos from the BigMDPL n -body simulation, both with and without mock observational effects. We find that a hypothetical skewer through the center of the halo along the merger axis (more precisely, along the current separation vector of the two halos) has nearly twice the column density of a typical line of sight. With weak lensing measurements, which involve some spatial averaging, this ratio is reduced to 1.25, suggesting that existing constraints on the scattering cross section are biased high by about 25%.}, archive = {J_ApJ}, author = {David Wittman and Scott Adler and Rodrigo Stancioli}, doi = {10.3847/1538-4357/adfd4e}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {99}, shortjournal = {The Astrophys. J.}, title = {Line-of-sight bias in dark matter inferences from galaxy cluster mergers}, volume = {991}, year = {2025}, }
• (2025). Polarized emission of intrabinary shocks in spider pulsars from global 3D kinetic simulations. ApJ, 991(1), 98. (www)

  @article{ , abstract = {In spider pulsar systems, a relativistic intrabinary shock (IBS) forms when the pulsar wind collides with the massive outflow driven off the pulsar’s low-mass stellar companion. The shock is a site of nonthermal particle acceleration, likely via shock-driven magnetic reconnection, and produces synchrotron emission. These shocks are among the few systems in which global scales can be reasonably captured with kinetic simulations, enabling first-principles particle acceleration and emission studies. We perform the first global 3D kinetic simulations of spider pulsar IBSs and predict their polarized emission properties. We report emission spectra, light curves, and polarization patterns as a function of the stripe-averaged magnetic field, cooling strength, and viewing inclination. At 90° inclination and for a low stripe-averaged magnetic field, we reproduce the double peaked light curve observed in spider systems. We predict a significant polarization degree ≳15%, which monotonically increases with the stripe-averaged field strength. Our results can be applied to and tested by forthcoming X-ray polarization observations of spider pulsars.}, archive = {J_ApJ}, author = {Andrew G. Sullivan and Jorge Cortés and Lorenzo Sironi}, doi = {10.3847/1538-4357/adfdcd}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {98}, shortjournal = {The Astrophys. J.}, title = {Polarized emission of intrabinary shocks in spider pulsars from global 3D kinetic simulations}, volume = {991}, year = {2025}, }
• (2025). Measurements of the perpendicular correlation length of coronal alfvénic waves with DKIST. ApJ, 991(1), 97. (www)

  @article{ , abstract = {We have measured the perpendicular correlation length L ⊥ of Alfvénic waves in the corona using data from the Daniel K. Inouye Solar Telescope (DKIST) Cryogenic Near Infrared Spectropolarimeter (Cryo-NIRSP) instrument. These data have high spatial resolution and were collected using a raster, enabling us to unambiguously identify the parallel and perpendicular directions with respect to the wave propagation. We find that the measured median L ⊥ ≈ 3.5 Mm, which is about half the value found by previous measurements. We ascribe the smaller value measured here to the improved spatial resolution of DKIST. There is a gradual decrease of L ⊥ as a function of frequency. We also computed the spatial correlation length of the observed static density structures and found that their typical correlation lengths of ≈8.4 Mm were significantly larger than those of the waves.}, archive = {J_ApJ}, author = {Michael Hahn and Stefan J. Hofmeister and Alexandros Koukras and Daniel Wolf Savin}, doi = {10.3847/1538-4357/ae017f}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {97}, shortjournal = {The Astrophys. J.}, title = {Measurements of the perpendicular correlation length of coronal alfvénic waves with DKIST}, volume = {991}, year = {2025}, }
• (2025). Cosmic-ray constraints on the flux of ultrahigh-energy neutrino event KM3-230213A. ApJ, 991(1), 96. (www)

  @article{ , abstract = {The detection of a ≃220 PeV muon neutrino event by the KM3NeT telescope offers an unprecedented opportunity to probe the Universe at extreme energies. A photopion interaction origin of the neutrino requires a parent cosmic-ray energy of ≳4 EeV per nucleon. We analyze the origin of this event under three scenarios, i.e., a transient point source, diffuse astrophysical emission, and a line-of-sight interaction of an ultrahigh-energy cosmic ray (UHECR; E ≳ 0.1 EeV). Our analysis includes the flux from both a KM3NeT-only fit and a joint fit, incorporating data from KM3NeT, IceCube, and the Pierre Auger Observatory. If the neutrino event originates from transients, it requires a new population of transients that is energetic, γ -ray-dark, and more abundant than the known ones. In the framework of diffuse astrophysical emission, we compare the required local UHECR energy injection rate at ≳4 EeV with the rate derived from the flux measurements by Auger, across various models of source redshift evolution. This disfavors the KM3NeT-only fit, considering the source evolution up to high values of redshift, while the joint fit remains viable for sources contributing up to a maximum redshift {z}_{{\rm{\max }}}\gtrsim 1 for the limiting case of photopion interaction efficiency, f pγ = 0.1. For a cosmogenic origin from point sources, the luminosity obtained at redshifts z ≲ 1 from the joint fit is compatible with the Eddington luminosity of ∼10 9 M ⊙ black holes in active galactic nuclei, assuming a proton composition and optimistic values of extragalactic magnetic field strength.}, archive = {J_ApJ}, author = {Saikat Das and Bing Zhang and Soebur Razzaque and Siyao Xu}, doi = {10.3847/1538-4357/adf8de}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {96}, shortjournal = {The Astrophys. J.}, title = {Cosmic-ray constraints on the flux of ultrahigh-energy neutrino event KM3-230213A}, volume = {991}, year = {2025}, }
• (2025). The HCO+/N2H+ flux ratio as a novel tracer of accretion burst activity in protostars. ApJ, 991(1), 95. (www)

  @article{ , abstract = {Massive young stellar objects (MYSOs) accrete mass primarily through episodic accretion events, yet detecting these events remains challenging, relying chiefly on infrared and maser variability. We investigated environmental changes during accretion burst and post-burst stages in the MYSO G36.115+0.552 using multiepoch 3 mm molecular lines observed with the Purple Mountain Observatory 13.7 m telescope during 2022–2023. Significant variability was detected in the HCO + (1–0)/N 2 H + (1–0) flux ratio. Radiative transfer analysis indicates this ratio variability likely results from temperature fluctuations driven by an accretion burst, as chemical processes operate on timescales exceeding our observational window. Correlation with a 6.7 GHz methanol maser light curve suggests the HCO + /N 2 H + ratio serves as a novel tracer of accretion bursts in MYSOs. This method complements infrared and maser techniques, providing a valuable tool for assessing the impact of accretion bursts on MYSO evolution.}, archive = {J_ApJ}, author = {Yufan Yang and Xi Chen and Yan-Kun Zhang and Jun-Ting Liu and Dengrong Lu and Bing-Gang Ju}, doi = {10.3847/1538-4357/adfdca}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {95}, shortjournal = {The Astrophys. J.}, title = {The HCO+/N2H+ flux ratio as a novel tracer of accretion burst activity in protostars}, volume = {991}, year = {2025}, }
• (2025). The impact of external radiation on the inner disk chemistry of planet formation. ApJ, 991(1), 94. (www)

  @article{ , abstract = {The vast majority of young stars hosting planet-forming disks exist within clustered environments, like the Orion Nebula, implying that seemingly “extreme” UV environments (10 4 G 0 and above) are not so atypical in the context of planet formation. Using thermochemical modeling, we explore how the temperature and chemistry within a protoplanetary disk around a T Tauri star are impacted by the surrounding UV environment. The disk becomes hotter due to heating by photodissociation of molecules, photoelectric heating, H 2 , and atomic processes, and as a result, the area in which molecules exist in the ice phase shrinks, being pushed both downward and inward. Beyond 1 au, the chemistry changes most significantly in a UV-rich background; the atmosphere becomes more H 2 O, OH, and atomic-rich. Hydrocarbons, however, reside primarily well within 1 au of the disk; thus, their abundance and distribution are not impacted by the UV field up to 10 6 G 0 . The products of photodissociation and photochemistry are formed deeper into the disk with increasing UV background field strength beyond 1 au, impacting the chemistry near the midplane. Effectively, a “reset” chemistry takes place, with an enhancement of atoms, simple molecules, and molecules in the gas phase. Planets that form in highly irradiated regions will be exposed to a different chemical reservoir in the gas and ice phases than that in an isolated disk, and the impact from the UV background should only be detectable in highly irradiated disks (∼10 6 G 0 ).}, archive = {J_ApJ}, author = {Jenny K. Calahan and Karin Öberg and Alice Booth}, doi = {10.3847/1538-4357/adfa09}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {94}, shortjournal = {The Astrophys. J.}, title = {The impact of external radiation on the inner disk chemistry of planet formation}, volume = {991}, year = {2025}, }
• (2025). Probing the energy-dependent temporal nature of MAXI j1803-298 with AstroSat and NICER. ApJ, 991(1), 93. (www)

  @article{ , abstract = {We perform a spectral and temporal analysis of MAXI J1803-298, using AstroSat/Large Area X-ray Proportional Counters and Neutron Star Interior Composition Explorer observations taken in 2021 May, during the initial phase of the outburst. We find that the source traverses through the hard, intermediate, and soft spectral states during the outburst. The spectrum in all states can be described using soft emissions from the thermal disk and hard emissions from the coronal regions. The variation in the inner-disk temperature and normalization of the disk indicate the motion of the truncated disk across these different spectral states. We confirm the presence of broad features, type C, and type B quasiperiodic oscillations in the power spectra of the different spectral states. We investigate the fractional rms and lags of all the variability features and discover that the lags swing between positive and negative during the outburst evolution. While modeling the features with a simple model that considers variations in accretion parameters, such as the accretion rate, heating rate, and inner-disk radius, along with the delays between them, we find a dynamic reversal in the origin of the variability between the corona and the disk. Furthermore, our results are consistent with previous works and a radio study conducted on this source during its outburst.}, archive = {J_ApJ}, author = {Arbind Pradhan and Akash Garg and Ranjeev Misra and Biplob Sarkar}, doi = {10.3847/1538-4357/adfa72}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {93}, shortjournal = {The Astrophys. J.}, title = {Probing the energy-dependent temporal nature of MAXI j1803-298 with AstroSat and NICER}, volume = {991}, year = {2025}, }
• (2025). The Warm–Hot Disk–Halo interface below the perseus spiral arm*. ApJ, 991(1), 92. (www)

  @article{ , abstract = {The Milky Way’s disk–halo interface mediates energy and mass exchange between the interstellar thin disk and the halo. In the first detailed study of the Perseus arm’s disk–halo interface, we combine Hubble Space Telescope/Space Telescope Imaging Spectrograph and Cosmic Origins Spectrograph absorption spectra toward six stars and 23 active galactic nuclei (AGNs) projected behind a narrow section (95° < l < 145°, −46° < b < 0°). This provides a unique data set that bridges the disk and its extended vertical structure in these directions. We measure S ii , Si iv , and C iv absorption, along with H i 21 cm emission, at heights −70 pc to −3.3 kpc from the midplane. The arm’s southern vertical structure shows distinct height-dependent behaviors: H i and S ii column densities sharply decline with height up to 1.5 kpc, then continue declining at a much shallower rate at greater heights. In contrast, high ion (Si IV and C IV ) column densities remain relatively constant throughout the entire height range. In the disk–halo interface, where warm neutral medium dominates, S ii and the high ions show similar kinematics, and we find a remarkably uniform C iv /Si iv ratio (〈 N C IV / N Si IV 〉  = 2.5 ± 0.5) within −0.9 to −3.25 kpc. Both the kinematic correspondence and high-ion ratio are consistent with the high ions probing turbulent mixing layers at the interfaces between warm/cool and hot gas phases. The AGN sight lines reveal minimal circumgalactic medium contribution in the low-velocity gas at ∣ v LSR ∣ < 100 km s −1 . The extraplanar absorbing gas may trace material ejected from previous Galactic fountain activity.}, archive = {J_ApJ}, author = {Ananya G. Tuli and Nicolas Lehner and J. Christopher Howk and Todd M. Tripp and Andrew J. Fox and Frances H. Cashman}, doi = {10.3847/1538-4357/adf192}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {92}, shortjournal = {The Astrophys. J.}, title = {The Warm–Hot Disk–Halo interface below the perseus spiral arm*}, volume = {991}, year = {2025}, }
• (2025). Gemini near infrared Spectrograph–Distant quasar survey: The chandra view. ApJ, 991(1), 91. (www)

  @article{ , abstract = {We present Chandra observations of 63 sources from the Gemini Near Infrared Spectrograph−Distant Quasar Survey, of which 54 were targeted by snapshot observations in Cycle 24. A total of 55 sources are clearly detected in at least one X-ray band, and we set stringent upper limits on the X-ray fluxes of the remaining eight sources. In combination with rest-frame ultraviolet–optical spectroscopic data for these sources, we assess whether X-rays can provide a robust accretion rate indicator for quasars, particularly at the highest accessible redshifts. We utilize a recently modified H β -based Eddington luminosity ratio estimator, as well as the C iv λ 1549 emission-line parameter space, to investigate trends and correlations with the optical–X-ray spectral slope ( α ox ) and the effective hard X-ray power-law photon index (Γ). We find that α ox does not improve current accretion rate estimates based on H β or C iv . Instead, within the limitations of our sample, we confirm previous findings that the C iv parameter space may be a better indicator of the accretion rate up to z ∼ 3.5. We also find that the average Γ values for a small subset of our sources, as well as the average Γ value in different groupings of our sources, are consistent with their respective relatively high Eddington luminosity ratios. Deeper X-ray observations of our X-ray-detected sources are needed for measuring Γ accurately and testing whether this parameter can serve as a robust, unbiased accretion rate diagnostic.}, archive = {J_ApJ}, author = {Andrea Marlar and Ohad Shemmer and Michael S. Brotherton and Gordon T. Richards and Cooper Dix and Brandon M. Matthews and W. N. Brandt and R. M. Plotkin}, doi = {10.3847/1538-4357/adf4dd}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {91}, shortjournal = {The Astrophys. J.}, title = {Gemini near infrared Spectrograph–Distant quasar survey: The chandra view}, volume = {991}, year = {2025}, }
• (2025). Physics-motivated models of pulsar X-ray hotspots: Off-center dipole configurations. ApJ, 991(1), 90. (www)

  @article{ , abstract = {Recently, it was proposed that an off-center dipole magnetic configuration, together with a nontrivial temperature profile, may be the best model to explain the X-ray light curve of PSR J0030+0451 observed by the Neutron Star Interior Composition Explorer. Using a theoretical model for the electric current density in a force-free pulsar magnetosphere, we compute from first principles the distribution of electric current over the polar cap associated with an off-center magnetic dipole. We then use a simple prescription to compute the resulting temperature distribution, which allows us to derive the observed X-ray light curve. We investigate the role of the volumetric return current region in the polar cap and find that although it does not make a big difference in the case of an aligned dipole, the difference can be bigger in the case of an off-center dipole. Finally, we apply Markov Chain Monte Carlo fitting to the X-ray light curves of pulsars PSR J0030+0451 and PSR J0437–4715 with and without the volumetric return current, and find that our model can reasonably recover the observed X-ray light curves.}, archive = {J_ApJ}, author = {Chun Huang and Alexander Y. Chen}, doi = {10.3847/1538-4357/adf747}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {90}, shortjournal = {The Astrophys. J.}, title = {Physics-motivated models of pulsar X-ray hotspots: Off-center dipole configurations}, volume = {991}, year = {2025}, }
• (2025). Variability in black hole accretion: Dependence on rotational and magnetic energy balance. ApJ, 991(1), 89. (www)

  @article{ , abstract = {Most general-relativistic magnetohydrodynamic simulations of black hole (BH) hot accretion flows are initialized with small rotating tori and produce stable jets with only small fluctuations. However, recent studies using larger-scale Bondi-like initial conditions have reported intermittent jet activity and loss of coherent rotation. To investigate these differences, we modify the standard torus setup across four BH spins: a * = 0, 0.5, 0.9, −0.9. First, we increase the torus size significantly (pressure maximum at 500 gravitational radii), allowing long simulations (2.8 × 10 5 gravitational times) without gas depletion. These runs reproduce the weak variability seen in smaller tori, indicating that a larger dynamic range alone does not cause strong fluctuations. We observe moderate suppression of the accretion rate by factors of ∼1.6 and 2.5 for BH spins a * = 0.5 and 0.9, respectively, compared to a * = 0. Also, the density profile scales as ρ ( r ) ∝ r −1.1 for prograde BHs. Next, we considerably strengthen the initial magnetic field in the large torus by setting the plasma- β ≈ 1. This induces strong variability in the evolution. The jet efficiency in the a * = 0.9 model, for instance, now varies by over 3 orders of magnitude, and the gas rotation reverses directions. Combining these results with prior studies, we propose that a key parameter is the ratio { \mathcal R } between the rotational and magnetic energies in the initial state. Strong variability appears later in models with larger values of { \mathcal R } . The implication is that all simulations, and by extension all hot accretion flows in nature, will ultimately develop intermittent jets if evolved long enough.}, archive = {J_ApJ}, author = {Hyerin Cho and Ramesh Narayan}, doi = {10.3847/1538-4357/adf8d3}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {89}, shortjournal = {The Astrophys. J.}, title = {Variability in black hole accretion: Dependence on rotational and magnetic energy balance}, volume = {991}, year = {2025}, }
• (2025). Helicity fluxes and hemispheric helicity rule of active regions emerging from the convection zone dynamo. ApJ, 991(1), 88. (www)

  @article{ , abstract = {Using a 3D nonlinear mean field solar dynamo model, we investigate the magnetic helicity flux and magnetic twist, as well as tilt parameters of bipolar magnetic regions (BMRs) emerging from the solar convection zone owing to the magnetic buoyancy instability. The twist and tilt of the BMR magnetic field are modeled as a result of an effective electromotive force along the rising part of the toroidal magnetic field. This force generates the poloidal field that tilts the whole magnetic configuration. We find that variations of BMR’s twist and tilt determine the magnitude and the sign of the magnetic helicity flux on the solar surface. The model shows that the helicity flux associated with the BMR’s tilt/twist is the dominant contribution to the BMR helicity at the beginning of the BMR’s evolution, while the effect of differential rotation is the main source of the helicity flux at the final stage of the BMR’s evolution. We discuss the implications of these effects on the basic properties and variations of the hemispheric helicity rule of active regions on the solar surface.}, archive = {J_ApJ}, author = {Valery V. Pipin and Shangbin Yang and Alexander G. Kosovichev}, doi = {10.3847/1538-4357/adf8e9}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {88}, shortjournal = {The Astrophys. J.}, title = {Helicity fluxes and hemispheric helicity rule of active regions emerging from the convection zone dynamo}, volume = {991}, year = {2025}, }
• (2025). CIBER fourth flight fluctuation analysis: Pseudopower spectrum formalism, improved source masking, and validation on mocks. ApJ, 991(1), 87. (www)

  @article{ , abstract = {Precise, unbiased measurements of extragalactic background anisotropies require careful treatment of systematic effects in fluctuation-based, broadband intensity mapping measurements. In this paper, we detail improvements in methodology for the Cosmic Infrared Background Experiment (CIBER), concentrating on flat field errors and source masking errors. In order to bypass the use of field differences, which mitigate flat field errors but reduce sensitivity, we characterize and correct for the flat field on pseudopower spectra, which includes both additive and multiplicative biases. To more effectively mask point sources at 1.1 and 1.8 μ m, we develop a technique for predicting masking catalogs that utilizes optical and near-infrared photometry through random forest regression. This allows us to mask over 2 Vega mag deeper than the completeness limits of Two Micron All Sky Survey alone, with errors in the shot noise power remaining below <10% at all masking depths considered. Through detailed simulations of CIBER observations, we validate our formalism and demonstrate unbiased recovery of the sky fluctuations on realistic mocks. We demonstrate that residual flat field errors comprise <20% of the final CIBER power spectrum uncertainty with this methodology.}, archive = {J_ApJ}, author = {Richard M. Feder and James J. Bock and Yun-Ting Cheng and Asantha Cooray and Phillip M. Korngut and Shuji Matsuura and Chi H. Nguyen and Kohji Takimoto and Michael Zemcov and CIBER collaboration}, doi = {10.3847/1538-4357/adfa1a}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {87}, shortjournal = {The Astrophys. J.}, title = {CIBER fourth flight fluctuation analysis: Pseudopower spectrum formalism, improved source masking, and validation on mocks}, volume = {991}, year = {2025}, }
• (2025). Resolved stellar and nebular kinematics of a star-forming galaxy at z ∼ 2. ApJ, 991(1), 86. (www)

  @article{ , abstract = {The kinematics of star-forming galaxy populations at high redshifts are integral to our understanding of disk properties, merger rates, and other defining characteristics. Nebular gas emission is a common tracer of galaxies’ gravitational potential and angular momenta, but is sensitive to nongravitational forces as well as galactic outflows, and thus might not accurately trace the host galaxy dynamics. We present kinematic maps of young stars from rest-ultraviolet photospheric absorption in the star-forming galaxy CASSOWARY 13 (a.k.a. SDSS J1237+5533) at z = 1.87 using the Keck Cosmic Web Imager, alongside nebular emission measurements from the same observations. Gravitational lensing magnification of the galaxy enables good spatial sampling of multiple independent lensed images. We find close agreement between the stellar and nebular velocity fields. We measure a mean local velocity dispersion of σ = 64 ± 12 km s −1 for the young stars, consistent with that of the H ii regions traced by nebular C iii ] emission (52  ±  9 km s −1 ). The ∼20 km s −1 average difference in line-of-sight velocity is much smaller than the local velocity width and the velocity gradient (≳100 km s −1 ). We find no evidence of asymmetric drift nor evidence that outflows bias the nebular kinematics, and thus we conclude that nebular emission appears to be a reasonable dynamical tracer of young stars in the galaxy. These results support the picture of star formation in thick disks with high velocity dispersion at z ∼ 2, and they represent an important step toward establishing robust kinematics of early galaxies using collisionless tracers.}, archive = {J_ApJ}, author = {Sunny Rhoades and Tucker Jones and Keerthi Vasan G. C. and Yuguang Chen and Nicha Leethochawalit and Richard Ellis and Anowar J. Shajib and Karl Glazebrook and Kris Mortensen and Ryan L. Sanders}, doi = {10.3847/1538-4357/adfa22}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {86}, shortjournal = {The Astrophys. J.}, title = {Resolved stellar and nebular kinematics of a star-forming galaxy at z ∼ 2}, volume = {991}, year = {2025}, }
• (2025). Unveiling the origin of fast radio bursts by modeling the stellar mass and star formation distributions of their host galaxies. ApJ, 991(1), 85. (www)

  @article{ , abstract = {Diverse formation channels have been proposed to explain the emergence of fast radio bursts (FRBs), yet their origin remains elusive. With improved localization precision, roughly 90 FRBs are now associated with host galaxies. Spectral energy distribution fitting to the host galaxy photometry reveals their stellar masses ( M ⋆ ) and star formation rates (SFRs), enabling discrimination between various formation channels. We conduct an extensive comparison of the stellar mass, SFR, and redshift distributions of 51 FRB hosts and mock generated galaxy samples to test whether FRBs trace SFR or M ⋆ . We incorporate a mass-to-light ratio ( {({{M}}_{\star }/{{L}}_{{r}})}_{{\rm{obs}}} ) prescription to address optical selection biases. In line with K. Sharma et al., we provide evidence in favor of FRB progenitors tracking SFR rather than stellar mass. We show that the shape of the assumed {({M}_{\star }/{L}_{r})}_{{\rm{o}}{\rm{b}}{\rm{s}}} distribution affects the predictions, bringing the low-mass end of the stellar mass distribution closer to the data when accounting for the {\mathrm{SFR}}\mbox{--}{({M}_{\star }/{L}_{r})}_{{\mathrm{obs}}} correlation. The K -correction effect in the r band is minimal for galaxies at z ≲ 0.7. In the model in which FRBs trace SFR, up to ∼6% of a flux-limited FRB host sample can reside below the star-forming main sequence. Finally, we examine a hybrid model in which a fraction of FRBs tracks stellar mass rather than SFR. This fraction can be as large as ∼40%−50%, suggesting that multiple formation channels are still consistent with observations. The toolkit developed in this work, GALFRB ( https://github.com/loudasnick/GALFRB ; N. Loudas et al.), is publicly available, offering a straightforward way to generate mock galaxy samples suitable for direct comparisons with future FRB host galaxy data.}, archive = {J_ApJ}, author = {Nick Loudas and Dongzi Li and Michael A. Strauss and Joel Leja}, doi = {10.3847/1538-4357/adf555}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {85}, shortjournal = {The Astrophys. J.}, title = {Unveiling the origin of fast radio bursts by modeling the stellar mass and star formation distributions of their host galaxies}, volume = {991}, year = {2025}, }
• (2025). Euclid quick data release (Q1)—Spectroscopic search, classification, and analysis of ultracool dwarfs in the deep fields. ApJ, 991(1), 84. (www)

  @article{ , abstract = {The Near-Infrared Spectrometer and Photometer on board the Euclid space mission has obtained near-infrared (NIR) slitless spectra of millions of objects, including hundreds of ultracool dwarfs (UCDs). Euclid observations retrieve images and spectra simultaneously. This observing mode marks a new era in the discovery of new objects, such as L- and T-type dwarfs, which can be found from direct identification through the H 2 O and CH 4 absorption bands. NISP spectral resolution ( R ∼  450) is enough to classify the objects by the spectral type using known standard templates. Q1 provided more than 4 million NIR spectra in one visit to the Euclid Deep Fields. The large amount of spectra released in these fields allowed us to (a) confirm the UCD nature of almost half of the photometric candidates compiled by J. Y. Zhang et al.; (b) discover at least 11 new late L- and T-type dwarfs by a specific spectral index search in Q1 data; and (c) spectroscopically confirm 100 more candidates from a new photometric selection conducted by M. Žerjal et al. We present a preliminary list of Euclid UCD templates built by the combination of the best spectra from all these searches. We include the first spectral analysis of confirmed UCDs from Q1 data; spectral classifications; determination of effective temperatures; H 2 O, CH 4 , and NH 3 spectral indices; and measurements of the K I absorption doublet. This paper is a first step in the study of Euclid UCDs and will be improved with each subsequent data release.}, archive = {J_ApJ}, author = {C. Dominguez-Tagle and M. Žerjal and N. Sedighi and P. Mas-Buitrago and E. L. Martin and J.-Y. Zhang and N. Vitas and V. J. S. Béjar and S. Tsilia and S. Muñoz Torres and N. Lodieu and D. Barrado and E. Solano and P. Cruz and R. Tata and N. Phan-Bao and A. Burgasser}, doi = {10.3847/1538-4357/adf72d}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {84}, shortjournal = {The Astrophys. J.}, title = {Euclid quick data release (Q1)—Spectroscopic search, classification, and analysis of ultracool dwarfs in the deep fields}, volume = {991}, year = {2025}, }
• (2025). Caught in the act: Detections of recoiling supermassive black holes from simulations. ApJ, 991(1), 83. (www)

  @article{ , abstract = {We study the detectability of supermassive black holes (SMBHs) with masses of M • ≳ 10 9 M ⊙ displaced by gravitational wave recoil kicks ( v kick = 0–2000 km s −1 ) in simulations of merging massive ( M ⋆ > 10 11 M ⊙ ) early-type galaxies. The used Ketju code combines the gadget-4 fast multiple gravity solver with accurate regularized integration and post-Newtonian corrections (up to PN3.5) around SMBHs. The ejected SMBHs carry clusters of bound stellar material (black hole recoil clusters, BRCs) with masses in the range of 10 6 ≲ M BRC ≲ 10 7 M ⊙ and sizes of several 10 pc. For recoil velocities up to 60% of the galaxy escape velocity, the BRCs are detectable in mock photometric images at a Euclid-like resolution up to redshift z ∼ 1.0. By Monte Carlo sampling the observability for different recoil directions and magnitudes, we predict that in ∼20% of instances the BRCs are photometrically detectable, most likely for kicks with SMBH apocentres less than the galaxy effective radius. BRCs occupy distinct regions in the stellar mass/velocity dispersion versus size relations of known star clusters and galaxies. An enhanced velocity dispersion in excess of σ ∼ 600 km s −1 coinciding with the SMBH position provides the best evidence for an SMBH-hosting stellar system, effectively distinguishing BRCs from other faint stellar systems. BRCs are promising candidates to observe the aftermath of the yet-undetected mergers of the most massive SMBHs and we estimate that up to 8000 BRCs might be observable below z ≲ 0.6 with large-scale photometric surveys such as Euclid and upcoming high-resolution imaging and spectroscopy with the Extremely Large Telescope.}, archive = {J_ApJ}, author = {Alexander Rawlings and Peter H. Johansson and Thorsten Naab and Antti Rantala and Jens Thomas and Bianca Neureiter}, doi = {10.3847/1538-4357/adf84a}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {83}, shortjournal = {The Astrophys. J.}, title = {Caught in the act: Detections of recoiling supermassive black holes from simulations}, volume = {991}, year = {2025}, }
• (2025). TeV afterglows of gamma-ray bursts: Theoretical analysis and prospects for future observations. ApJ, 991(1), 82. (www)

  @article{ , abstract = {Recent detections of gamma-ray bursts (GRBs) at TeV energies opened new prospects for investigating radiative environments and particle acceleration mechanisms under extreme conditions. In this paper, we study the afterglows of these GRBs—namely GRB 180720B, GRB 190114C, GRB 190829A, GRB 201216C, and GRB 221009A—modeling their synchrotron and inverse Compton emission within the framework of an optimized relativistic fireball model. We constrain the model parameters and their temporal evolution by applying our theoretical model to the high-energy emission in the X-ray and GeV–TeV energy bands observed at intermediate and late times. Our results reveal interesting differences among the TeV-detected GRBs, potentially reflecting a variety of underlying physical processes that lead to different maximum energies {E}_{{\rm{\max }}}=\,{\gamma }_{{\rm{\max }}}\,{m}_{e}\,{c}^{2} of the accelerated particles responsible for the GRB high-energy emission. We indeed obtain different behaviors of the late TeV afterglows that ultimately depend on {\gamma }_{{\rm{\max }}} . We discuss how late afterglow observations—on timescales of hours and days—of X-ray and GeV–TeV emissions are crucial for providing diagnostics of the physical processes behind GRBs, and we emphasize the theoretical expectations for future TeV observations.}, archive = {J_ApJ}, author = {Luca Foffano and Marco Tavani}, doi = {10.3847/1538-4357/adf8e3}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {82}, shortjournal = {The Astrophys. J.}, title = {TeV afterglows of gamma-ray bursts: Theoretical analysis and prospects for future observations}, volume = {991}, year = {2025}, }
• (2025). Dynamics of low-mass black hole seeds in the BRAHMA simulations using subgrid dynamical friction: Impact on merger-driven black hole growth in the high-redshift universe. ApJ, 991(1), 81. (www)

  @article{ , abstract = {We analyze the dynamics of low-mass black hole (BH) seeds in the high-redshift ( z ≳ 5) Universe using a suite of [4.5 Mpc] 3 and [9 Mpc] 3 BRAHMA cosmological hydrodynamic simulations. The simulations form seeds with mass M seed = 2.2 × 10 3 M ⊙ in halos that exceed critical thresholds of dense and metal-poor gas mass (5–150 M seed ) and the halo mass (1000–10,000 M seed ). While the initial BRAHMA boxes pinned the BHs to the halo centers, here we implement a subgrid dynamical friction (DF) model. We also compare simulations where the BH is allowed to wander without the added DF. We investigate the spatial and velocity offsets of BHs in their host subhalos, as well as BH merger rates. We find that subgrid DF is crucial to ensure that a significant fraction of BHs effectively sink to halo centers by z ∼ 5, thereby enabling them to get gravitationally bound and merge with other BHs at separations close to the spatial resolution (∼0.2–0.4 kpc) of the simulation. For the BHs that merge, the associated merger timescales lag between ∼100 and 1000 Myr after their host halos merge. Compared to predictions using BH repositioning, the overall z ≳ 5 BH merger rates under subgrid DF decrease by a factor of ∼4–10. Under subgrid DF, the different seed models predict merger rates between ∼100 and 1000 events per year at z ≳ 5. These mergers dominate early BH growth, assembling BHs up to ∼10 4 –10 5 M ⊙ by z ∼ 5, wherein ≲2% of their mass is assembled via gas accretion. Our results highlight the promise for constraining seeding mechanisms using gravitational waves from future facilities such as the Laser Interferometer Space Antenna.}, archive = {J_ApJ}, author = {Aklant K. Bhowmick and Laura Blecha and Luke Z. Kelley and Aneesh Sivasankaran and Paul Torrey and Rainer Weinberger and Nianyi Chen and Mark Vogelsberger and Lars Hernquist and Priyamvada Natarajan and Tiziana Di Matteo}, doi = {10.3847/1538-4357/adf96b}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {81}, shortjournal = {The Astrophys. J.}, title = {Dynamics of low-mass black hole seeds in the BRAHMA simulations using subgrid dynamical friction: Impact on merger-driven black hole growth in the high-redshift universe}, volume = {991}, year = {2025}, }
• (2025). Polarization signatures of quasiperiodic oscillations in simulated tilted, truncated disks. ApJ, 991(1), 80. (www)

  @article{ , abstract = {We utilize the Monte Carlo radiation transport code, Pandurata , to create images, spectra, polarization maps, and light curves from a set of general relativistic magnetohydrodynamic simulations of tilted, truncated, black hole accretion disks. Truncation can have spectral and polarization signatures all its own, tilt introduces both inclination and azimuthal dependencies into the spectra and polarization, and precession and oscillations of the tilted accretion flow inside the truncation radius introduce time dependencies or periodicity to all of this. We use the ray-traced results from our simulations to evaluate the feasibility of measuring these effects, particularly in the context of current and future X-ray polarization observatories. Such detections could greatly improve our understanding of the geometry of accretion disks and coronae in the hard state, the physics of quasiperiodic oscillations, and how system properties evolve as sources approach the hard-to-soft state transition.}, archive = {J_ApJ}, author = {P. Chris Fragile and Deepika A. Bollimpalli and Jeremy D. Schnittman and Cesare Harvey}, doi = {10.3847/1538-4357/adfde1}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {80}, shortjournal = {The Astrophys. J.}, title = {Polarization signatures of quasiperiodic oscillations in simulated tilted, truncated disks}, volume = {991}, year = {2025}, }
• (2025). A magnetic field detection in the massive O-type bright giant 63 oph. ApJ, 991(1), 79. (www)

  @article{ , abstract = {Surface magnetic fields are detected in less than 10% of the massive O-type star population and even less frequently among “old” massive stars approaching the terminal-age main sequence (TAMS). It is unclear to what extent the rarity of magnetic detections in massive stars near the TAMS is due to magnetic field decay or observational biases. We report the detection of a weak surface magnetic field in the O-type giant 63 Oph ( T eff = 35.0 ± 0.3 kK, {\mathrm{log}}\,g=3.51\pm 0.03 ) from new ESPaDOnS circularly polarized spectra. The mean longitudinal field strength associated with the magnetic detection is 〈 B z 〉 = 84 ± 14 G, which we use to set a lower limit on the dipolar field strength of B p ≥ 300 ± 50 G. We report Balmer line-core equivalent widths (EWs) and radial velocity measurements from the analysis of spectra primarily obtained by the IACOB project with the FEROS, FIES, and HERMES spectrographs. We identify a dominant period of ∼19.8 days in the EWs, which we attribute to the effects of a rotating magnetosphere under the oblique rotator model. We do not identify any coherent signals in a time series analysis of archival Hipparcos, ASAS-SN, and K2 photometry. Our findings show that 63 Oph may be a rare link between strongly magnetic massive stars detected on or near the zero-age main sequence and weakly magnetic O-type supergiants. Additional observations are needed to fully constrain 63 Oph’s magnetic field geometry and magnetospheric properties.}, archive = {J_ApJ}, author = {James A. Barron and Gregg A. Wade and Gonzalo Holgado and Sergio Simón-Díaz}, doi = {10.3847/1538-4357/adf6d9}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {79}, shortjournal = {The Astrophys. J.}, title = {A magnetic field detection in the massive O-type bright giant 63 oph}, volume = {991}, year = {2025}, }
• (2025). The averaged broadband spectral energy distribution study of fermi bright BL lac objects. ApJ, 991(1), 78. (www)

  @article{ , abstract = {The physics-determined broadband spectral energy distributions (SEDs) of blazars have been widely used to study their properties during their flaring/outburst states, while the nonflaring state takes up most of their lifetime and the general property of blazars has been barely discussed. In this work, for the first time, we used the archival data and employed the physics-determined SED processing method to form approximately average-state SEDs for 513 Fermi bright BL Lacs. In general, we found that the magnetic field ( B ) is weaker than those obtained for the flaring/outburst state by nearly 1 order of magnitude, and the dissipation region size ( R ) is larger than those obtained for the flaring/outburst state, suggesting that the dissipation region could be more extended and less magnetized. A correlation between the synchrotron self-Compton peak frequency ( {\mathrm{log}}\,{\nu }_{{{\rm{ssc}}}} ) and the synchrotron peak frequency ( {\mathrm{log}}\,{\nu }_{{{\rm{sy}}}} ) suggests that the inverse Compton scattering of higher-synchrotron-peaked BL Lacs suffers a significant Klein–Nishina (KN) suppression; we quantified the condition of KN suppression by determining the critical synchrotron peak frequency ( {\nu }_{{{\rm{sy}}}^{{\rm{c}}}} ) and found 359 out of 513 sources in our sample suffer KN suppression. Furthermore, our analysis of the relationship between synchrotron curvature (1/ b sy ) and {\mathrm{log}}\,{\nu }_{{{\rm{sy}}}} indicates that the energy-dependent probability acceleration mechanism may dominate the particle acceleration in BL Lac jets.}, archive = {J_ApJ}, author = {Hubing Xiao and Haitao Cao and Rui Xue and Zhihao Ouyang and Shaohua Zhang and Junping Chen and Zhijian Luo and Jianghe Yang and Junhui Fan}, doi = {10.3847/1538-4357/adf7ad}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {78}, shortjournal = {The Astrophys. J.}, title = {The averaged broadband spectral energy distribution study of fermi bright BL lac objects}, volume = {991}, year = {2025}, }
• (2025). A data-constrained magnetohydrodynamic simulation of successive X-class flares in solar active region 13842. II. dynamics of the solar eruption associated with the x9.0 solar flare. ApJ, 991(1), 77. (www)

  @article{ , abstract = {Active region NOAA 13842 produced two successive solar flares: an X7.1-class flare on 2024 October 1, and an X9.0-class flare on 2024 October 3. This study continues our previous simulation work that successfully reproduced the X7.1-class solar flare. In this study, we performed a data-constrained magnetohydrodynamic simulation using the nonlinear force-free field (NLFFF) as the initial condition to investigate the X9.0-class solar flare. The NLFFF showed the sheared field lines, resulting in the tether-cutting reconnection, the magnetic flux ropes, and eventually led to eruption. The magnetic reconnection during the pre-eruption phase plays a critical role in accelerating the subsequent eruption, which is driven by torus instability and magnetic reconnection. Furthermore, our simulation results are consistent with several observational features associated with the X9.0 flare. This simulation could reproduce diverse phenomena associated with the X9.0 flare, including the tether-cutting reconnection, the flare ribbons and the postflare loops, the transverse field enhancement, and the remote brightening away from the flare ribbons. However, the initial trigger, magnetic flux emergence, was inferred from observations rather than explicitly modeled, and future comprehensive simulations should incorporate this mechanism directly.}, archive = {J_ApJ}, author = {Keitarou Matsumoto and Satoshi Inoue and Keiji Hayashi and Nian Liu and Ying Wang and Jeongwoo Lee and Ju Jing and Haimin Wang}, doi = {10.3847/1538-4357/adfa20}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {77}, shortjournal = {The Astrophys. J.}, title = {A data-constrained magnetohydrodynamic simulation of successive X-class flares in solar active region 13842. II. dynamics of the solar eruption associated with the x9.0 solar flare}, volume = {991}, year = {2025}, }
• (2025). Star clusters in the near-ultraviolet-optical-near-infrared: Spectral energy distribution modeling with direct markers of gas and dust emission. ApJ, 991(1), 76. (www)

  @article{ , abstract = {The large number of star clusters in nearby galaxies permits us to statistically test the predictions of stellar, dust, and gas models. Using Hubble Space Telescope (HST) broadband plus H α imaging combined with JWST near-infrared imaging, we use a total of 10 filters spanning near-ultraviolet through near-infrared wavelengths to model key physical parameters, including age, mass, and reddening, of 6130 star clusters in 16 nearby spiral galaxies from the Physics at High Angular resolution in Nearby GalaxieS sample, focusing on their ages, masses, and reddenings. We find that HST/H α and JWST/NIRCam 2–3.6 μ m photometry significantly improves our ability to disentangle the age–reddening degeneracy between young, gas- and dust-rich clusters and older, dustless clusters. The near-infrared data provide strong constraints on hot continuum dust and small polycyclic aromatic hydrocarbon emission for populations where gas and dust are present. These hot dust constraints demonstrate that Bruzual & Charlot stellar population models do not align with the observed near-ultraviolet-optical-near-infrared spectral energy distributions of star clusters in the first 10 Myr. We note that for old and low-metallicity globular clusters, the inclusion of narrowband H α and/or broadband near-infrared data does not improve the determination of age and reddening parameters, due to the lack of stars capable of heating dust in the near-infrared regime.}, archive = {J_ApJ}, author = {Kiana F. Henny and Daniel A. Dale and Rupali Chandar and Médéric Boquien and David A. Thilker and Bradley C. Whitmore and Janice C. Lee and M. Jimena Rodriguez and Daniel Maschmann and Aida Wofford and Rémy Indebetouw and Leonardo Úbeda and Brent Groves and Hamid Hassani and Kirsten L. Larson and Thomas G. Williams and Kathryn Grasha and Francesca Pinna and Stephen Hannon}, doi = {10.3847/1538-4357/ade440}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {76}, shortjournal = {The Astrophys. J.}, title = {Star clusters in the near-ultraviolet-optical-near-infrared: Spectral energy distribution modeling with direct markers of gas and dust emission}, volume = {991}, year = {2025}, }
• (2025). Subparsec acceleration and collimation of NGC 4261’s twin jets. ApJ, 991(1), 75. (www)

  @article{ , abstract = {We report the first robust evidence for a cospatial subparsec acceleration and collimation zone (ACZ) in the twin jets of the nearby low-luminosity active galactic nucleus NGC 4261. This result is derived from multifrequency Very Long Baseline Array imaging, combined with the frequency-dependent properties of the radio core (core shift and core size) and jet kinematics determined from the jet-to-counterjet brightness ratio. By applying multiple analysis methods and incorporating results from the literature, we identify a parabolic-to-conical structural transition in both the jet and counterjet, with the transition occurring at (1.23 ± 0.24) pc or (8.1 ± 1.6) × 10 3 R s (Schwarzschild radii) for the jet and (0.97 ± 0.29) pc or (6.4 ± 1.9) × 10 3 R s for the counterjet. We also derive the jet velocity field at distances of ∼(10 3 –2 × 10 4 ) R s . While local kinematic variations are present, the jet shows an overall acceleration to relativistic speeds from ∼10 3 to ∼8 × 10 3 R s , with a maximum Lorentz factor of {{\rm{\Gamma }}}_{{\rm{\max }}}\approx 2.6 . Beyond this region, the jet gradually decelerates to subrelativistic speeds. These findings support the existence of a subparsec-scale (≲1.5 pc) ACZ in NGC 4261, where the jet is accelerated via magnetic-to-kinetic energy conversion while being confined by external pressure. A brief comparison with M87 suggests that the ACZ in NGC 4261 may represent a scaled-down analog of that in M87. These results point toward a potential diversity in jet ACZ properties, emphasizing the importance of extending such studies to a broader AGN population to elucidate the physical mechanisms at play.}, archive = {J_ApJ}, author = {Xi Yan and Lang Cui and Kazuhiro Hada and Sándor Frey and Ru-sen Lu and Liang Chen and Wancheng Xu and Elika P. Fariyanto and Luis C. Ho}, doi = {10.3847/1538-4357/adf84c}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {75}, shortjournal = {The Astrophys. J.}, title = {Subparsec acceleration and collimation of NGC 4261’s twin jets}, volume = {991}, year = {2025}, }
• (2025). A search for z = 5 hα and hβ + [O iii] dual-line emitting galaxies in the JWST CEERS field: Implications for the active galactic nucleus abundance. ApJ, 991(1), 74. (www)

  @article{ , abstract = {The James Webb Space Telescope (JWST) has enabled us to uncover faint galaxies and active galactic nuclei (AGNs) in the early Universe. Leveraging the filter combination used in the Cosmic Evolution Early Release Science Survey program, we perform an extensive photometric search of galaxies emitting strong H β + [O iii ] and H α lines. The redshift range of the galaxies is limited to 5.03 ≤ z ≤ 5.26 by requiring photometric excess in NIRCam’s F277W and F410M images. A total of 259 H β + [O iii ] and H α dual-line emitters are found over the absolute UV magnitude −22 ≲ M UV ≲ −17, with a mean rest-frame equivalent width of 990 Å for H β + [O iii ] and 1050 Å for H α . This population accounts for ∼40% of the Lyman-break galaxies at this redshift range. Intriguingly, there are 58 objects (22% of the whole sample) that exhibit compact morphology at the rest-UV or optical wavelength. Assuming that these compact dual-line emitters are dominated by AGNs, their bolometric luminosities are in the range of 2 × 10 43 ≲ L bol /(erg s −1 ) ≲ 3 × 10 44 . Their number density is 2 dex higher than the extrapolation from UV-selected luminous quasars, which is in good agreement with previous JWST studies of broad-line AGNs, requiring a ∼10% AGN duty cycle. Moreover, our dual-line emitter sample reaches the faint end of the H α and [O iii ] luminosity functions down to ≲10 42 erg s −1 . Spectroscopic follow-up observations are planned in a JWST Cycle 3 program, in which we aim to confirm their nature, characterize their black hole activity, and construct their mass distribution at 10 6 ≲ M BH / M ⊙ ≲ 10 8 .}, archive = {J_ApJ}, author = {Jingsong Guo and Masafusa Onoue and Kohei Inayoshi and Dale D. Kocevski and Steven L. Finkelstein and Micaela B. Bagley and Elizabeth J. McGrath}, doi = {10.3847/1538-4357/adee0f}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {74}, shortjournal = {The Astrophys. J.}, title = {A search for z = 5 hα and hβ + [O iii] dual-line emitting galaxies in the JWST CEERS field: Implications for the active galactic nucleus abundance}, volume = {991}, year = {2025}, }
• (2025). Probing binary architectures of lithium-rich giants in GALAH with COSMIC and stellar models. ApJ, 991(1), 73. (www)

  @article{ , abstract = {Surface lithium is depleted when a star goes through the first dredge-up phase, yet 1% of red giants are found to be Li rich. The formation mechanism for these remains uncertain. We combine observational constraints from Galactic Archaeology with HERMES ( GALAH ) Li-rich giants, with the binary population synthesis software Compact Object Synthesis and Monte Carlo Investigation Code ( COSMIC) to investigate the system properties of these objects assuming binary mass transfer. By evolving nine million binary systems, we find that binary histories most consistent with the observational constraints are mass transfer from an intermediate-mass asymptotic giant branch (AGB) donor to a main-sequence (MS) star now observed as a Li-rich red giant. In GALAH , 9% of MS stars have A (Li) = 2.5–3.2 dex making it plausible to create red giants with A (Li) = 1.5–2.2 dex via MS mass transfer, but they cannot explain the more enriched giants with A (Li) ≳ 2.2 dex. Nucleosynthetic yields from stellar models show that AGB stars with initial masses of 4.25–5 M ⊙ and 8 M ⊙ contain the most lithium in their ejecta. Intermediate-mass AGB stars comprise 29% of the COSMIC results, with present-day separations s = 3.3 ± 0.5 au and mass ratios q = 0.5–1.6. We achieve 95% agreement in mean enhancements in Ba and Y between the GALAH observations and stellar models of 6 and 8 M ⊙ AGB stars, assuming a 1% mass transfer efficiency. We find a low mass transfer efficiency best reproduces the GALAH observations suggesting that the preferred mass transfer mechanism for Li enrichment is via wind Roche-lobe overflow. While we constrain the most plausible binary parameters assuming AGB mass transfer creates Li-rich giants, discrepancies in the nucleosynthesis comparisons and the small fraction of Li-enhanced MS stars suggests additional enrichment mechanisms are likely.}, archive = {J_ApJ}, author = {Maryum Sayeed and Selina F. Yang and Giulia Cinquegrana and Melissa K. Ness and Katelyn Breivik and Andrew R. Casey and Sven Buder and Amanda I. Karakas}, doi = {10.3847/1538-4357/adef05}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {73}, shortjournal = {The Astrophys. J.}, title = {Probing binary architectures of lithium-rich giants in GALAH with COSMIC and stellar models}, volume = {991}, year = {2025}, }
• (2025). Cosmography with the double-source-plane strong gravitational lens AGEL150745+052256. ApJ, 991(1), 72. (www)

  @article{ , abstract = {Strong gravitational lenses with two background sources at widely separated redshifts are a promising independent probe of cosmological parameters. We can use these systems, known as double-source-plane lenses (DSPLs), to measure the ratio ( β ) of angular-diameter distances of the sources, which is sensitive to the matter density (Ω m ) and the equation-of-state parameter for dark-energy ( w ). However, DSPLs are rare and require high-resolution imaging and spectroscopy for detection, lens modeling, and measuring β . Here, we report only the second DSPL ever used to measure cosmological parameters. We model the DSPL AGEL 150745+052256 from the ASTRO 3D Galaxy Evolution with Lenses ( AGEL ) survey using Hubble Space Telescope/Wide-Field Camera 3 imaging and Keck Cosmic Web Imager spectroscopy. The spectroscopic redshifts for the deflector and two sources in AGEL 1507 are z defl = 0.594, z S1 =  2.163, and z S2 = 2.591. We measure a stellar velocity dispersion of σ obs = 109 ± 27 km s −1 for the nearer source (S1). Using σ obs for the main deflector (from literature) and S1, we test the robustness of our DSPL model. We measure \beta =0.95{3}_{-0.010}^{+0.008} for AGEL 1507 and infer Ω m =\,0.3{3}_{-0.23}^{+0.38} for ΛCDM cosmology. Combining AGEL 1507 with the published model of the Jackpot lens improves the precision on Ω m (ΛCDM) and w ( w CDM) by ∼10%. The inclusion of DSPLs significantly improves the constraints when combined with Planck’s cosmic microwave background observations, enhancing the precision on w by 30%. This paper demonstrates the potential constraining power of DSPLs and their complementarity to other standard cosmological probes. Tighter future constraints from larger DSPL samples discovered from ongoing and forthcoming large-area sky surveys would provide insights into the nature of dark energy.}, archive = {J_ApJ}, author = {Nandini Sahu and Anowar J. Shajib and Kim-Vy Tran and Hannah Skobe and Sunny Rhoades and Tucker Jones and Karl Glazebrook and Thomas E. Collett and Sherry H. Suyu and Keerthi Vasan G. C. and Tania M. Barone and Duncan J. Bowden and Daniel Ballard and Glenn G. Kacprzak and Sarah M. Sweet and Geraint F. Lewis and Themiya Nanayakkara}, doi = {10.3847/1538-4357/adf442}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {72}, shortjournal = {The Astrophys. J.}, title = {Cosmography with the double-source-plane strong gravitational lens AGEL150745+052256}, volume = {991}, year = {2025}, }
• (2025). Radiative magnetohydrodynamics simulation of minidisks in equal-mass massive black hole binaries. ApJ, 991(1), 71. (www)

  @article{ , abstract = {We are on the cusp of detecting gravitational waves (GWs) from individual massive black hole binaries (MBHBs) with the Laser Interferometer Space Antenna and pulsar timing arrays. These MBHBs may be surrounded by circumbinary disks and minidisks, the electromagnetic emission from which is essential for localizing the MBHBs on the sky. Here we present the first radiative magnetohydrodynamics (RMHD) minidisk simulation that directly solves the radiative transfer equation on discretized grid rays. The simulation examines one of the minidisks in an equal-mass 2 × 10 7 M ⊙ MBHB separated by 100 gravitational radii. Minidisks simulated with and without radiative effects resemble each other qualitatively but differ in several key aspects. The RMHD minidisk is denser and geometrically thinner than the magnetohydrodynamics minidisk. Furthermore, the RMHD minidisk, with a nonaxisymmetric photosphere and temperature distribution, produces an anisotropic illumination pattern. As a result, the observed radiative flux of two RMHD minidisks orbiting each other varies at half the binary orbital period, a feature independent of relativistic boosting and lensing effects. Such periodic light curves, if identified in upcoming optical transient surveys, could reveal the existence of MBHBs on the way to merger, particularly if they are in a constant phase relation with detected GWs.}, archive = {J_ApJ}, author = {Chi-Ho Chan and Vishal Tiwari and Tamara Bogdanović and Yan-Fei Jiang and Shane W. Davis}, doi = {10.3847/1538-4357/adf4c9}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {71}, shortjournal = {The Astrophys. J.}, title = {Radiative magnetohydrodynamics simulation of minidisks in equal-mass massive black hole binaries}, volume = {991}, year = {2025}, }
• (2025). Results of 15 yr pulsar timing of PSR j0007+7303 with fermi-LAT. ApJ, 991(1), 70. (www)

  @article{ , abstract = {The study of pulsar glitches provides a unique window into the internal structure and dynamic processes of neutron stars. PSR J0007+7303, a very bright gamma-ray pulsar, is the first pulsar discovered by the Fermi–Large Area Telescope (LAT) telescope. In this paper, we present the 15 yr of timing results of this pulsar using the Fermi-LAT data. We identified nine glitches, five of which are newly discovered. Among these new glitches, two are small glitches, occurring between the three previously reported ones, while the other three are large glitches. The glitches exhibit fractional frequency changes ranging from 21.5 × 10 −9 to 1239 × 10 −9 , with intervals of approximately 1–2 yr between events. Uniquely, this pulsar shows no exponential recovery behavior following any glitch, setting it apart from most glitching pulsars. Furthermore, no significant changes were observed in the gamma-ray pulse profile, flux, or phase-averaged spectra before and after glitches, indicating the stability of the pulsar’s emission properties despite internal changes. A parametric analysis of the glitches yielded a fractional moment of inertia of the crustal superfluid involved in glitches as 1.06%, which matches extremely well with previous statistical work if the nondissipative entrainment effect is not considered and strongly supports the internal origin of these glitches. These results highlight the distinct glitch behavior of PSR J0007+7303 and offer valuable insights into the crust–superfluid interaction in neutron stars. The physical origin of no exponential recovery is also discussed.}, archive = {J_ApJ}, author = {Zhi-xiang Yu and Shi-jun Dang and Wei-hua Wang and Hui-hui Wang and Lin Li and Wei Li and Jian-ping Yuan and Fei-fei Kou and Jun-tao Bai and Mingyu Ge and Xia Zhou and Lun-hua Shang and Zu-rong Zhou and Yu-bin Wang and Yan-qing Cai and Ru-shuang Zhao and Qing-ying Li and Xiang-dong Zeng and Na Wang}, doi = {10.3847/1538-4357/adf4d6}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {70}, shortjournal = {The Astrophys. J.}, title = {Results of 15 yr pulsar timing of PSR j0007+7303 with fermi-LAT}, volume = {991}, year = {2025}, }
• (2025). SIDM concerto: Compilation and data release of self-interacting dark matter zoom-in simulations. ApJ, 991(1), 69. (www)

  @article{ , abstract = {We present SIDM Concerto: 14 cosmological zoom-in simulations in cold dark matter (CDM) and self-interacting dark matter (SIDM) models based on the Symphony and Milky Way-est suites. SIDM Concerto includes one Large Magellanic Cloud– (LMC-) mass system (host mass ∼10 11 M ⊙ ), two Milky Way (MW) analogs (∼10 12 M ⊙ ), two group-mass hosts (∼10 13 M ⊙ ), and one low-mass cluster (∼10 14 M ⊙ ). Each host contains ≈2 × 10 7 particles and is run in CDM and one or more strong, velocity-dependent SIDM models. Our analysis of SIDM (sub)halo populations over seven subhalo mass decades reveals that (1) the fraction of core-collapsed isolated halos and subhalos peaks at a maximum circular velocity corresponding to the transition of the SIDM cross section from a v −4 to v 0 scaling; (2) SIDM subhalo mass functions are suppressed by ≈50% relative to CDM in LMC, MW, and group-mass hosts but are consistent with CDM in the low-mass cluster host; (3) subhalos’ inner density profile slopes, which are more diverse in SIDM than in CDM, are sensitive to both the amplitude and shape of the SIDM cross section. Our simulations provide a benchmark for testing SIDM predictions with astrophysical observations of field and satellite galaxies, strong lensing systems, and stellar streams. Data products are publicly available at doi:10.5281/zenodo.14933624.}, archive = {J_ApJ}, author = {Ethan O. Nadler and Demao Kong and Daneng Yang and Hai-Bo Yu}, doi = {10.3847/1538-4357/adf553}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {69}, shortjournal = {The Astrophys. J.}, title = {SIDM concerto: Compilation and data release of self-interacting dark matter zoom-in simulations}, volume = {991}, year = {2025}, }
• (2025). Linear polarization in a black hole, 4U 1957+115 and its X-ray spectral analysis. ApJ, 991(1), 68. (www)

  @article{ , abstract = {We present a new spectropolarimetric method for the estimation of the inclination of X-ray binaries using the linear polarization (LP) value in black hole (BH) sources, based on the early paper by R. A. Sunyaev & L. G. Titarchuk. The X-ray LP arises from multiple scattering of initially soft photons in a hot, optically thick Compton cloud (CC) using a flat geometry. R. A. Sunyaev & L. G. Titarchuk showed that the LP degree P depends on the binary inclination i and remains independent of the photon energy. Moreover, P follows a characteristic angular distribution based on the CC optical depth τ 0 ; in particular, for τ 0 > 10, the LP follows the S. Chandrasekhar distribution. In light of the vast number of recent IXPE spectropolarimetric observations of BHs, testing this approach in combination with spectral analysis of these sources by other missions is desirable. In particular, the BH source, 4U 1957+115, was observed with IXPE in the high/soft state for which a P of ∼ 2% was found. To apply the new method, in addition to knowing P for a given source, it is necessary to estimate the CC optical depth τ 0 and then to calculate the best-fit photon index Γ and the plasma temperature kT e . We present the X-ray spectral analysis of 4U 1957+115 using data from IXPE , NuSTAR, NICER, RXTE, Swift, Suzaku, and ASCA. We show that the X-ray source spectra are well described by the Comptonization model with Γ varying from 1.5 to 3. We find a monotonic increase in Γ with the mass accretion rate, \dot{M} , and a final saturation of the index at Γ ∼ 3 for high \dot{M} . We determine a BH mass by the scaling method: M 1957 = 4.8 ± 1.8 M ⊙ , assuming a source distance of 22 kpc, using H 1743–322, 4U 1630–47, and GRS 1915+105 as reference sources.}, archive = {J_ApJ}, author = {Lev Titarchuk and Elena Seifina and Paolo Soffitta and Diana Makhinya}, doi = {10.3847/1538-4357/adf55a}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {68}, shortjournal = {The Astrophys. J.}, title = {Linear polarization in a black hole, 4U 1957+115 and its X-ray spectral analysis}, volume = {991}, year = {2025}, }
• (2025). X-ray polarization detection of the pulsar wind nebula in g21.5–0.9 with IXPE. ApJ, 991(1), 67. (www)

  @article{ , abstract = {We present the X-ray polarization observation of G21.5−0.9, a young Galactic supernova remnant (SNR), conducted with the Imaging X-ray Polarimetry Explorer (IXPE) in 2023 October, with a total livetime of approximately 837 ks. Using different analysis methods, such as a space-integrated study of the entire region of the pulsar wind nebula (PWN) and a space-resolved polarization map, we detect significant polarization from the PWN at the center of the SNR, with an average polarization degree of ∼10% oriented at ∼33° (north through east). No significant energy-dependent variation in polarization is observed across the IXPE band (2–8 keV). The polarization map, corrected for the effect of polarization leakage, reveals a consistent pattern in both degree and angle, with little change across the nebula. Our findings indicate the presence of a highly polarized central torus, suggesting low levels of turbulence at particle acceleration sites. Unlike Vela, but similar to the Crab Nebula, we observe substantial differences between radio and X-ray polarization maps. This suggests a clear separation in energy of the emitting particle populations and hints at an important, yet poorly understood, role of instabilities in the turbulence dynamics of PWNe.}, archive = {J_ApJ}, author = {Niccolò Di Lalla and Nicola Omodei and Niccolò Bucciantini and Jack T. Dinsmore and Nicolò Cibrario and Stefano Silvestri and Josephine Wong and Patrick Slane and Tsunefumi Mizuno and Michela Negro and Roger W. Romani and Riccardo Ferrazzoli and C.-Y. Ng and Miltiadis Michailidis and Yi-Jung Yang and Fei Xie and Martin C. Weisskopf and Philip Kaaret and Iván Agudo and Lucio A. Antonelli and Matteo Bachetti and Luca Baldini and Wayne H. Baumgartner and Ronaldo Bellazzini and Stefano Bianchi and Stephen D. Bongiorno and Raffaella Bonino and Alessandro Brez and Fiamma Capitanio and Simone Castellano and Elisabetta Cavazzuti and Chien-Ting Chen and Stefano Ciprini and Enrico Costa and Alessandra De Rosa and Ettore Del Monte and Laura Di Gesu and Alessandro Di Marco and Immacolata Donnarumma and Victor Doroshenko and Michal Dovčiak and Steven R. Ehlert and Teruaki Enoto and Yuri Evangelista and Sergio Fabiani and Javier A. Garcia and Shuichi Gunji and Jeremy Heyl and Wataru Iwakiri and Svetlana G. Jorstad and Vladimir Karas and Fabian Kislat and Takao Kitaguchi and Jeffery J. Kolodziejczak and Henric Krawczynski and Fabio La Monaca and Luca Latronico and Ioannis Liodakis and Simone Maldera and Alberto Manfreda and Frédéric Marin and Andrea Marinucci and Alan P. Marscher and Herman L. Marshall and Francesco Massaro and Giorgio Matt and Ikuyuki Mitsuishi and Fabio Muleri and Stephen L. O’Dell and Chiara Oppedisano and Alessandro Papitto and George G. Pavlov and Abel Lawrence Peirson and Matteo Perri and Melissa Pesce-Rollins and Pierre-Olivier Petrucci and Maura Pilia and Andrea Possenti and Juri Poutanen and Simonetta Puccetti and Brian D. Ramsey and John Rankin and Ajay Ratheesh and Oliver J. Roberts and Carmelo Sgró and Paolo Soffitta and Gloria Spandre and Douglas A. Swartz and Toru Tamagawa and Fabrizio Tavecchio and Roberto Taverna and Yuzuru Tawara and Allyn F. Tennant and Nicholas E. Thomas and Francesco Tombesi and Alessio Trois and Sergey Tsygankov and Roberto Turolla and Jacco Vink and Kinwah Wu and Silvia Zane}, doi = {10.3847/1538-4357/adf6b5}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {67}, shortjournal = {The Astrophys. J.}, title = {X-ray polarization detection of the pulsar wind nebula in g21.5–0.9 with IXPE}, volume = {991}, year = {2025}, }
• (2025). Semianalytic modeling of dark matter subhalo encounters with thin stellar streams: Statistical predictions for GD-1-like streams in cold dark matter. ApJ, 991(1), 66. (www)

  @article{ , abstract = {Stellar streams from disrupted globular clusters are dynamically cold structures that are sensitive to perturbations from dark matter subhalos, allowing them in principle to trace the dark matter substructure in the Milky Way. We model, within the context of Λ cold dark matter, the likelihood of dark matter subhalos to produce a significant feature in a GD-1-like stream and analyze the properties of such subhalos. We generate many realizations of the subhalo population within a Milky Way mass host halo using the semianalytic code SatGen , accounting for effects such as tidal stripping and dynamical friction. The subhalo distributions are combined with a GD-1-like stream model, and the impact of subhalos that pass close to the stream are modeled with Gala . We find that subhalos with masses in the range 2 × 10 6 M ⊙ –10 8 M ⊙ at the time of the stream–subhalo encounter, corresponding to masses of about 2 × 10 7 M ⊙ –10 9 M ⊙ at the time of infall, are the likeliest to produce gaps in a GD-1-like stream. We find that gaps occur on average ∼3 times per realization of the host system. These gaps have typical widths of ∼(5–27)° and fractional underdensities of ∼(10–30)%, with larger gaps being caused by heavier subhalos. The stream–subhalo encounters responsible for these have impact parameters (0.1–1.5) kpc and relative velocities ∼(200–410) km s −1 . We also investigate the effects of increasing the host-halo mass on the gap properties and formation rate.}, archive = {J_ApJ}, author = {Duncan K. Adams and Aditya Parikh and Oren Slone and Rouven Essig and Manoj Kaplinghat and Adrian M. Price-Whelan}, doi = {10.3847/1538-4357/adf740}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {66}, shortjournal = {The Astrophys. J.}, title = {Semianalytic modeling of dark matter subhalo encounters with thin stellar streams: Statistical predictions for GD-1-like streams in cold dark matter}, volume = {991}, year = {2025}, }
• (2025). Precise parameters for two LISA sources. ApJ, 991(1), 65. (www)

  @article{ , abstract = {We present precise parameters for two compact double white dwarf (DWD) binaries, SDSS J232230.20+050942.0 (J2322+0509) and SDSS J063449.92+380352.2 (J0634+3803), with orbital periods of 20 and 26.5 minutes, respectively. These systems will serve as verification sources for the Laser Interferometer Space Antenna (LISA). To significantly improve the electromagnetic (EM) constraints on these two systems and the LISA detectability predictions, we conducted spectroscopic follow-up observations using Hubble Space Telescope/Space Telescope Imaging Spectrograph, Keck I/LRIS, and Keck II/Echellette Spectrograph and Imager. Our analysis significantly improves the temperature, surface gravity, and mass constraints for both primary and secondary components in J2322+0509, as well as dynamical properties such as radial velocities and orbital periods in both systems. For J2322+0509, we derive an updated inclination of i = 25 {}_{-3.0}^{+4.5} deg, while for J0634+3803, we obtain i = 43 {}_{-5.6}^{+7.0} deg. We assess the detectability of these sources using LDASOFT. Incorporating EM priors on inclination significantly enhances the gravitational-wave signal recovery, reducing uncertainties in amplitude by a factor of 2–4 and shortening the detection time by up to a few months. Our results underscore the importance of multimessenger observations in characterizing DWD binaries and maximizing LISA’s early scientific capabilities.}, archive = {J_ApJ}, author = {Manuel Barrientos and Mukremin Kilic and Warren R. Brown and Fatma Ben Daya and Antoine Bédard and Tyson Littenberg and Thomas Kupfer and Snehalata Sahu}, doi = {10.3847/1538-4357/adf743}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {65}, shortjournal = {The Astrophys. J.}, title = {Precise parameters for two LISA sources}, volume = {991}, year = {2025}, }
• (2025). Three-component phase separation for ultramassive white dwarf models. ApJ, 991(1), 64. (www)

  @article{ , abstract = {We investigate phase separation in oxygen-neon (O/Ne) ultramassive white dwarfs (UMWDs). Current stellar evolution codes, such as MESA, only account for 16 O/ 20 Ne separation and do not include other minor species. To improve this, we implement ternary phase diagrams into MESA. We construct UMWD models with O/Ne/sodium (Na) and O/Ne/magnesium (Mg) cores to test our implementation. We also assess the effect of including 22 Ne in the current two-species framework. Our results show that incorporating additional components into the phase separation significantly alters the chemical evolution of UMWDs. Heavier elements preferentially enrich the solid core, enhancing mixing in the overlying liquid. We compute the buoyancy flux driven by compositional instabilities during crystallization. As in previous studies, we find two convective regimes: an early, fast overturning convection, lasting less than a million years, followed by inefficient (thermohaline) convection. The fast convective regime lasts up to 100 times longer with three-species separation compared to the standard 16 O/ 20 Ne case. We find that neutron-rich species can have a significant contribution to the buoyancy flux despite their small mass fraction (<10%). We compute the amount of cooling delay induced by phase separation in UMWDs, and find that the three-species phase separation produces a delay of up to ∼10 times larger than the simplest case of fractionation, although still less than 1 Gyr. We predict that the change in the composition profile in the liquid region when three components are included should change the frequency of gravity modes that can propagate in the interior of pulsating UMWDs.}, archive = {J_ApJ}, author = {Matias Castro-Tapia and Andrew Cumming}, doi = {10.3847/1538-4357/adf745}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {64}, shortjournal = {The Astrophys. J.}, title = {Three-component phase separation for ultramassive white dwarf models}, volume = {991}, year = {2025}, }
• (2025). Can fractal dimension distinguish between grand-design and flocculent spiral arms?. ApJ, 991(1), 63. (www)

  @article{ , abstract = {About two-thirds of disk galaxies host spiral arms, ranging from well-delineated grand-design spirals to fragmented flocculent spiral galaxies. We introduce fractal dimension D B as a nonparametric measure to distinguish between grand-designs and flocculents. We calculate the D B of 197 grand-designs and 322 flocculents from Sloan Digital Sky Survey (SDSS) DR18, using the samples of R. J. Buta et al. ( 2015 ) and S. Sarkar et al. ( 2023 ). Our calculated median values of D B are 1.2{9}_{-0.04}^{+0.06} and 1.3{8}_{-0.06}^{+0.05} for the grand-designs and flocculents, respectively. In addition, a Kolmogorov–Smirnov (K-S) test rejects the null hypothesis that these distributions are drawn from the same population. Finally, using a random forest model, we compare the effectiveness of D B in classifying spiral arm morphology with that of five other parameters: the total atomic hydrogen H I mass, M HI; the ratio of atomic hydrogen mass to blue luminosity, M HI / L B ; concentration index, C i ; clumpiness, S ; and arm contrast, C . Our results indicate that D B has the highest feature index (30.8%), followed by C i (26.0%) and M HI (21.0%). In fact, C—the metric routinely used to distinguish between the spiral morphologies—has a feature importance of 8.3%. Further, D B for grand-designs is found to anticorrelate with the central velocity dispersion with a correlation coefficient of −0.3 and p ≪ 0.05. The high value of central velocity dispersion indicates a central Q -barrier, which favors the formation of grand-designs according to the density wave theory. Thus, the fractal dimension serves as a robust metric to distinguish between spiral morphologies and also links to the formation mechanism of the spiral features.}, archive = {J_ApJ}, author = {Biju Saha and Subhadip Dutta and Arunima Banerjee}, doi = {10.3847/1538-4357/adf840}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {63}, shortjournal = {The Astrophys. J.}, title = {Can fractal dimension distinguish between grand-design and flocculent spiral arms?}, volume = {991}, year = {2025}, }
• (2025). Thermonuclear heating of accreting neutron stars. ApJ, 991(1), 62. (www)

  @article{ , abstract = {We describe a new method to incorporate thermonuclear heating in the envelope of accreting neutron stars into long-term simulations of their thermal evolution. We obtain boundary conditions for the heat exchange between the envelope and the crust based on stationary models, which include nuclear burning, and validate these values by comparing them to the results of the time-dependent code MESA . These simple boundary conditions allow us to explore a large parameter space. We quantify the amount of heat flowing from the envelope into the crust, or vice versa, depending on the mass accretion rate, outburst duration, and duty cycle, and especially crust/core physical parameters such as impurities, crustal heating, and neutrino cooling rate.}, archive = {J_ApJ}, author = {Martín Nava-Callejas and Dany Page and Yuri Cavecchi}, doi = {10.3847/1538-4357/adf8e4}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {62}, shortjournal = {The Astrophys. J.}, title = {Thermonuclear heating of accreting neutron stars}, volume = {991}, year = {2025}, }
• (2025). Biermann battery magnetic flux generation in the deep solar interior. ApJ, 991(1), 61. (www)

  @article{ , abstract = {Time-series analyses of helioseismic data and solar neutrino data have indicated the potential existence of a second tachocline at the core–radiative zone interface, which may in turn require consideration of an additional source of magnetic flux generation in the deep solar interior ( r / R ⊙ ≲ 0.5). This work considers the generation of a Biermann battery magnetic flux in the deep solar interior and the potential transport of that magnetic flux outward by diffusion. At low latitudes, we expect this additional flux to interact with the flux generated at the base of the convective zone to result in the solar magnetic field observed near the ecliptic. At high latitudes, the diffused flux may manifest as scattered regions of intense polar fields that could be measured by appropriate instruments on spacecraft far off the ecliptic.}, archive = {J_ApJ}, author = {Robert D. Loper}, doi = {10.3847/1538-4357/adfec5}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {61}, shortjournal = {The Astrophys. J.}, title = {Biermann battery magnetic flux generation in the deep solar interior}, volume = {991}, year = {2025}, }
• (2025). Time-dependent MHD simulation of the lunar limb compression caused by the core-induced magnetic field. ApJ, 991(1), 60. (www)

  @article{ , abstract = {Using a time-dependent magnetohydrodynamic simulation, we demonstrated the lunar limb compression caused by the core-induced magnetic field. When a sudden change occurs in the upstream interplanetary magnetic field (IMF), an induced response is generated within the Moon’s conductive core. When the direction of the IMF jump is the same as the IMF direction after the jump, a diamagnetic current is driven inside the core, strengthening the magnetic field beneath the lunar surface but outside the core. In most dayside regions, this induced subsurface magnetic pressure is suppressed by the strong solar wind dynamic pressure. However, in regions near the terminator, where the solar wind dynamic pressure is lower, this induced subsurface magnetic pressure can compress the solar wind above the lunar surface, forming limb compression structures around the Moon. This work not only clarifies a new physical mechanism for the source of the lunar limb compression (driven by the core-induced magnetic field rather than the crustal magnetic field) but also ascertains the starting position of the limb compression, as well as its temporal variation during the IMF jump. These results can greatly improve our understanding of the Moon’s electromagnetic environment and have potential applications to constrain the conductive state of lunar core.}, archive = {J_ApJ}, author = {Siqi Yi and Xiaojun Xu and Lianghai Xie and Xing Wang and Qi Xu and Lei Li and Chi Wang}, doi = {10.3847/1538-4357/adff4c}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {60}, shortjournal = {The Astrophys. J.}, title = {Time-dependent MHD simulation of the lunar limb compression caused by the core-induced magnetic field}, volume = {991}, year = {2025}, }
• (2025). ALMA observations of molecular complexity in the large magellanic cloud: Probing the star-forming region n 160. ApJ, 991(1), 59. (www)

  @article{ , abstract = {Hot cores are small (≲0.1 pc), dense (≥10 6 cm −3 ), and hot (>100 K) regions around massive protostars and are one of the main production sites of complex organic molecules (COMs, ≥6 atoms, including carbon). The Large Magellanic Cloud (LMC) is an ideal place to study hot core and COM formation in an environment that is different from our Galaxy, though prior to this study there have only been nine detections of extragalactic hot cores (seven in the LMC and two in the Small Magellanic Cloud, SMC). Here, we report 1.2 mm continuum and molecular line observations with the Atacama Large Millimeter/submillimeter Array in the star-forming region N 160, which we named N 160A–mm. We identify six 1.2 mm continuum sources, four of which are associated with methanol (CH 3 OH) emission. Another COM, methyl cyanide (CH 3 CN) is associated with the brightest source, N 160A–mm A, the most chemically rich source in the field. Using the XCLASS software, we perform spectral modeling to estimate rotational temperatures and total column densities of detected molecular species for four sources. Based on the temperature exceeding 100 K, its small size, and high H 2 number density, we identify N 160A–mm A as a hot core. We compare the molecular abundances of this newly detected hot core with those previously detected in the LMC and SMC, as well as with a sample of Galactic hot cores, and discuss the complex nature of N 160A–mm A.}, archive = {J_ApJ}, author = {Amanda Broadmeadow and Marta Sewiło and Lee Mundy and Roya Hamedani Golshan and Kazuki Tokuda and Thomas Möller and Remy Indebetouw and Joana M. Oliveira and Steven B. Charnley and Jennifer Wiseman and Naoto Harada and Peter Schilke}, doi = {10.3847/1538-4357/ade9ae}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {59}, shortjournal = {The Astrophys. J.}, title = {ALMA observations of molecular complexity in the large magellanic cloud: Probing the star-forming region n 160}, volume = {991}, year = {2025}, }
• (2025). Supermassive black hole growth in hierarchically merging nuclear star clusters. ApJ, 991(1), 58. (www)

  @article{ , abstract = {Supermassive black holes are prevalent at the centers of massive galaxies, and their masses scale with galaxy properties, increasing evidence suggesting that these trends continue to low stellar masses. Seeds are needed for supermassive black holes, especially at the highest redshifts explored by the James Webb Space Telescope. We study the hierarchical merging of galaxies via cosmological merger trees and argue that the seeds of supermassive black holes formed in nuclear star clusters via stellar black hole mergers at early epochs. Observable tracers include intermediate-mass black holes, nuclear star clusters, and early gas accretion in host dwarf galaxies, along with a potentially detectable stochastic gravitational-wave background, ejection of intermediate and supermassive black holes, and consequences of a significant population of early tidal disruption events and extreme mass ratio inspirals.}, archive = {J_ApJ}, author = {Konstantinos Kritos and Ricarda S. Beckmann and Joseph Silk and Emanuele Berti and Sophia Yi and Marta Volonteri and Yohan Dubois and Julien Devriendt}, doi = {10.3847/1538-4357/adeb44}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {58}, shortjournal = {The Astrophys. J.}, title = {Supermassive black hole growth in hierarchically merging nuclear star clusters}, volume = {991}, year = {2025}, }
• (2025). The timing evolution of the magnetar swift j1818.0–1607 during a period of reduced activity. ApJ, 991(1), 57. (www)

  @article{ , abstract = {We report results from an observational campaign of the radio-loud magnetar Swift J1818.0−1607 using the Green Bank Telescope at 2.0 GHz that began in 2021 November, during a period of reduced activity approximately 20 months after its 2020 March outburst. Over the ∼60 day duration reported here, the integrated pulse profile remained consistently stable, exhibiting a single, narrow peak with a small precursor component and no evidence of a postcursor one. This pulse profile is in sharp contrast to the double-peaked morphology observed during an observing campaign ∼120 days preceding ours. Along with this change in the integrated pulse profile shape, we also measured a slower spin-down rate ( \dot{\nu } ) compared to the end of that preceding campaign. Together, these differences suggest that a mode-switching event likely occurred between the end of that campaign and the start of ours. Finally, we derived a phase-connected timing solution from our data, from which we inferred a characteristic age of τ c ∼ 2500 yr—about 2.5 times older than the most recent published estimate—and a surface dipole magnetic field strength of B field ∼ 1 × 10 14 G, nearly 3 times weaker. These updated estimates reflect the short-term variations in the magnetar’s spin-down rate, from which both its age and magnetic field strength are inferred, rather than intrinsic changes in the magnetar itself.}, archive = {J_ApJ}, author = {Moaz Abdelmaguid and Paulo C. C. Freire and Joseph D. Gelfand and Yogesh Maan and Samayra Straal and J. A. J. Alford}, doi = {10.3847/1538-4357/adf4df}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {57}, shortjournal = {The Astrophys. J.}, title = {The timing evolution of the magnetar swift j1818.0–1607 during a period of reduced activity}, volume = {991}, year = {2025}, }
• (2025). Revisiting galaxy cluster scaling relations through dark Matter–Gas coherence: Scatter dependence on dynamical state. ApJ, 991(1), 56. (www)

  @article{ , abstract = {Galaxy clusters, the most massive, dark-matter-dominated, and most recently assembled structures in the Universe, are key tools for probing cosmology. However, uncertainties in scaling relations that connect cluster mass to observables like X-ray luminosity and temperature remain a significant challenge. In this paper, we present the results of an extensive investigation of 329 simulated clusters from IllustrisTNG300 cosmological simulations. Our analysis involves cross-correlating dark matter and the hot X-ray-emitting gas, considering both the 3D and 2D projected distributions to account for projection effects. We demonstrate that this approach is highly effective in evaluating the dynamical state of these systems and validating the often-utilized assumption of hydrostatic equilibrium, which is key for inferring cluster masses and constructing scaling relations. Our study revisits both the X-ray luminosity–mass and X-ray temperature–mass scaling relations, and demonstrates how the scatter in these relations correlates with the clusters’ dynamical state. We demonstrate that matter–gas coherence enables the identification of an optimal set of relaxed clusters, reducing scatter in scaling relations by up to 40%. This innovative approach, which integrates higher-dimensional insights into scaling relations, might offer a new path to further reduce uncertainties in determining cosmological parameters from galaxy clusters.}, archive = {J_ApJ}, author = {Giulia Cerini and Elena Bellomi and Nico Cappelluti and Sabina Khizroev and Erwin T. Lau and Priyamvada Natarajan and John ZuHone}, doi = {10.3847/1538-4357/adf744}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {56}, shortjournal = {The Astrophys. J.}, title = {Revisiting galaxy cluster scaling relations through dark Matter–Gas coherence: Scatter dependence on dynamical state}, volume = {991}, year = {2025}, }
• (2025). Coronal cells in coronal holes: Systematic analysis and implications for coronal evolution. ApJ, 991(1), 55. (www)

  @article{ , abstract = {Using advanced processing techniques, we analyze high-cadence, high-resolution extreme-ultraviolet images and show that, throughout the solar cycle, midlatitude coronal holes (CHs) are made up of ubiquitous and space-filling funnel-shaped structures (or cells) anchored to unipolar magnetic flux concentrations in network lanes. We demonstrate that the coronal cells, previously documented in the magnetically closed regions, and coronal plumes, inside CHs, are a particular manifestation of ubiquitous cells. The cell properties depend on the magnetic field intensity at their footpoint and connectivity in the corona, either closing in opposite-polarity regions (CF-cells) or extending to form open field (OF-cells). The OF-cells reach size scales on the order of supergranules and are characterized by dark lanes delimiting ray-like features both showing, at different levels, persistent jetlike ejections. The cells’ lifetime mirrors that of magnetic flux concentrations revealed by magnetograms, slowly emerging and then disappearing in a matter of a few hours to a few days in a one-to-one correspondence. When a cell forms along the CH boundary, it can alter the CH boundary by shrinking or expanding the CH by an approximately supergranular cell unit. Therefore, coronal cells can contribute to the dynamics of the CH boundary. We contextualize these observations in a “coronal cell” theory potentially able to provide an explanation for fine-scale coronal structures and jetting activity in polar CHs.}, archive = {J_ApJ}, author = {Nathalia Alzate and Simone Di Matteo and Aleida Higginson}, doi = {10.3847/1538-4357/adf7a9}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {55}, shortjournal = {The Astrophys. J.}, title = {Coronal cells in coronal holes: Systematic analysis and implications for coronal evolution}, volume = {991}, year = {2025}, }
• (2025). Doppler-shifted signatures in the chromospheric line profiles of II pegasi. ApJ, 991(1), 54. (www)

  @article{ , abstract = {Stellar flares are frequently accompanied by prominence eruptions, coronal mass ejections (CMEs), and other forms of plasma motion. Based on the long-term high-resolution spectroscopic monitoring data set of the RS CVn-type star II Pegasi (II Peg), we search for stellar prominence eruptions and potential CMEs by investigating asymmetric signatures in the H α and H β line profiles during the flare events. We observed seven optical flares with asymmetric spectral profiles, releasing low limit energies of 10 33 –10 34 erg in the H α line. Five of these flares were associated with six potential CMEs, identified through the Doppler-shifted emission signatures in the chromospheric line profiles, particularly the H α line. The mass estimates for the CME candidates range from 10 19 to 10 20 g, while the kinetic energies are calculated to be around 10 33 –10 34 erg. The most massive CME candidate was simultaneously recorded in the H α , H β , and He i D 3 lines. For II Peg, the possible flare–CME association rate is about 30%. There were also some redshifted excess absorption signatures in the H α line profiles. These signatures could not only be observed in the flaring spectra but also in the spectra without flare, which could be interpreted as features resulting from flare-driven coronal rain and quiescent rain, respectively.}, archive = {J_ApJ}, author = {Dongtao Cao and Shenghong Gu}, doi = {10.3847/1538-4357/adf8eb}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {54}, shortjournal = {The Astrophys. J.}, title = {Doppler-shifted signatures in the chromospheric line profiles of II pegasi}, volume = {991}, year = {2025}, }
• (2025). HerS-3: An exceptional einstein cross reveals a massive dark matter halo. ApJ, 991(1), 53. (www)

  @article{ , abstract = {We present a study of HerS-3, a dusty star-forming galaxy at z spec = 3.0607, which is gravitationally amplified into an Einstein cross with a fifth image of the background galaxy seen at the center of the cross. Detailed 1 mm spectroscopy and imaging with NOEMA and the Atacama Large Millimeter/submillimeter Array resolve the individual images and show that each of the five images display a series of molecular lines that have similar central velocities, unambiguously confirming that they have identical redshifts. The Hubble Space Telescope F110W image reveals a foreground lensing group of four galaxies with a photometric redshift z phot ∼ 1.0. Lens models that only include the four visible galaxies are unable to reproduce the properties of HerS-3. By adding a fifth massive component, lying southeast of the brightest galaxy of the group, the source reconstruction is able to match the peak emission, shape, and orientation for each of the five images. The fact that no galaxy is detected near that position indicates the presence of a massive dark matter halo in the lensing galaxy group. In the source plane, HerS-3 appears as an infrared luminous starburst galaxy seen nearly edge on. The serendipitous discovery of this exceptional Einstein cross offers a potential laboratory for exploring at small spatial scales a nuclear starburst at the peak of cosmic evolution and studying the properties of a massive dark matter halo associated with the lensing galaxy group.}, archive = {J_ApJ}, author = {P. Cox and K. M. Butler and C. R. Keeton and L. Eid and E. Borsato and T. J. L. C. Bakx and R. Neri and B. M. Jones and P. Prajapati and A. J. Baker and S. Berta and A. Cooray and E. M. Corsini and L. Marchetti and A. Omont and A. Beelen and R. Gavazzi and D. Ismail and R. J. Ivison and M. Krips and M. D. Lehnert and H. Messias and D. Riechers and C. Vlahakis and A. Weiss and P. van der Werf and C. Yang}, doi = {10.3847/1538-4357/adf204}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {53}, shortjournal = {The Astrophys. J.}, title = {HerS-3: An exceptional einstein cross reveals a massive dark matter halo}, volume = {991}, year = {2025}, }
• (2025). Quantifying the active galactic nucleus fraction in cosmic voids via mid-infrared variability. ApJ, 991(1), 52. (www)

  @article{ , abstract = {Observations and theoretical simulations suggest that the large-scale environment plays a significant role in how galaxies form and evolve and, in particular, whether and when galaxies host an actively accreting supermassive black hole in their center (i.e., an active galactic nucleus; AGN). One signature of AGN activity is luminosity variability, which appears in the mid-IR when circumnuclear dust reprocesses UV and optical photons from the AGN accretion disk. We present here a suite of constraints on the fraction of AGN activity in the most underdense regions of the Universe (cosmic voids) relative to the rest of the Universe (cosmic walls) by using ∼12 yr of combined multiepoch data from AllWISE and NEOWISE to quantify mid-IR variability. We find clear evidence for a larger mid-IR variability−AGN fraction among high- and moderate-luminosity void galaxies compared to their wall counterparts. We also show that mid-IR variability identifies a rather large and unique population of AGNs, the majority of which have eluded detection using more traditional AGN selection methods such as single-epoch mid-IR color selection. The fraction of these newly recovered AGNs is larger among galaxies in voids, suggesting once again more prolific AGN activity in the most underdense large-scale structures of the Universe.}, archive = {J_ApJ}, author = {Anish S. Aradhey and Anca Constantin and Michael S. Vogeley and Kelly A. Douglass}, doi = {10.3847/1538-4357/adeca1}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {52}, shortjournal = {The Astrophys. J.}, title = {Quantifying the active galactic nucleus fraction in cosmic voids via mid-infrared variability}, volume = {991}, year = {2025}, }
• (2025). On the ordering of exoplanet systems. ApJ, 991(1), 51. (www)

  @article{ , abstract = {We present a comprehensive analysis of planetary radius ordering within multiplanet systems, namely their ordinal position with respect to their size in a given system, utilizing data from the NASA Exoplanet Archive. In addition, we consider not only the ordinal positions but also the specific period ratios and radius ratios of planetary pairs in multiplanet systems. We explore various dependencies on stellar host type and metallicity, as well as planetary type, and explore the differences between planetary systems with different planet multiplicities and different planetary pairs in the same system. Focusing on Kepler systems with two to four planets, we account for observational biases and uncover a robust trend of smaller inner planets. This trend is particularly pronounced in inner pairs of three-planet systems and exhibits variations in stellar metallicity and planet multiplicity. Notably, we find that the distribution of inner-to-outer planet radius ratios depends on the systems’ metallicities, suggesting a link between the initial conditions and the resulting system architecture. Interestingly, planet pairs in resonance do not exhibit significantly different size ratios compared to nonresonant pairs, challenging current theoretical expectations, again, possibly suggesting that initially resonant systems could have been later destabilized. Our findings align with planet formation and migration models where larger planets form farther out and migrate inward. Importantly, we emphasize the significance of planet ordering as a novel and crucial observable for constraining planet formation and evolution models. The observed patterns offer unique insights into the complex interplay of formation, migration, and dynamical interactions shaping planetary systems.}, archive = {J_ApJ}, author = {Michael Lozovsky and Hagai B. Perets}, doi = {10.3847/1538-4357/adf22b}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {51}, shortjournal = {The Astrophys. J.}, title = {On the ordering of exoplanet systems}, volume = {991}, year = {2025}, }
• (2025). Some interesting observations of cosmic ray variations during the extreme solar storm on 2024 may 10–11. ApJ, 991(1), 50. (www)

  @article{ , abstract = {Multiple interplanetary coronal mass ejections (ICMEs) erupted from AR 13664 during 2024 May 8–13. On 2024 May 10, after the arrival of the ICME shock at 17:04 UT, a Forbush Decrease (FD) was seen in various Neutron Monitor (NM) stations located worldwide. This paper presents a comprehensive analysis of neutron data from 28 NM stations and gamma-ray data obtained from the NaI(Tl) detector at Maitri, Antarctica. The present paper reports for the first time about an ICME shock-sheath related enhancement of ∼3%–5% magnitude in the neutron flux at stations with geomagnetic rigidity between 4 and 7 GV, located at higher altitudes (≥1000 m). For these stations, the high-rigidity ends of the asymptotic trajectories are confined to the midnight to the postmidnight region. It appears that the increase may be associated with magnetospheric particle precipitation triggered by the passage of the ICME shock-sheath. The variation of FD amplitude with rigidity shows a decreasing trend in general, with a minimum amplitude at 5–7 GV, which we attribute to the location of field-aligned currents (FACs). The FD amplitude is found to have the effects of storm-time westward ring current, FACs, and magnetospheric dynamics, in addition to the ICME parameters. During the recovery phase of FD, enhancement is observed between 01:50 and 03:00 UT on 2024 May 11, which coincided with Ground Level Enhancement (GLE#74). The GLE # 74 was coeval with the strong SYM-H index and the sudden recovery of the FD due to reduced interplanetary magnetic field, which might be responsible for the observed enhancement at high rigidity stations.}, archive = {J_ApJ}, author = {Pranali Thakur and Geeta Vichare}, doi = {10.3847/1538-4357/adf32c}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {50}, shortjournal = {The Astrophys. J.}, title = {Some interesting observations of cosmic ray variations during the extreme solar storm on 2024 may 10–11}, volume = {991}, year = {2025}, }
• (2025). Synergistic radiative transfer modeling of mg II and lyα emission in multiphase, clumpy galactic environments: Application to low-redshift lyman continuum leakers. ApJ, 991(1), 49. (www)

  @article{ , abstract = {We conducted systematic radiative transfer (RT) modeling of the Mg ii doublet line profiles for 33 low-redshift Lyman continuum (LyC) leakers, and Ly α modeling for six of these galaxies, using a multiphase, clumpy circumgalactic medium (CGM) model. Our RT models successfully reproduced the Mg ii emission line profiles for all galaxies, revealing a necessary condition for strong LyC leakage: high maximum clump outflow velocity ( {v}_{{\rm{MgII}},{\rm{\max }}}\gtrsim 390\,{\rm{km}}\,{{\rm{s}}}^{-1} ) and low total Mg ii column density ( N MgII, tot ≲ 10 14.3 cm −2 ). These two parameters have the strongest influence on the emergent Mg ii profile. For the six galaxies with archival HST data, our Ly α modeling shows that their spectral properties do not consistently match conventional LyC leakage criteria. A direct comparison of the best-fit Mg ii and Ly α model parameters reveals no clear correlations in clump outflow velocities, column densities, or volume filling factors, suggesting that H i and Mg ii may not be kinematically or spatially coherent. The inferred LyC escape fraction from Ly α modeling is primarily governed by the number of optically thick H i clumps per sightline ( f cl ). Intriguingly, two galaxies with low observed LyC leakage exhibited the highest RT-inferred LyC escape fractions, due to having the lowest f cl values, driven by strong Ly α blue peaks. Future spatially resolved observations will be crucial for resolving this puzzle. Our results support a “picket fence” CGM geometry over a “density-bounded” scenario, where high Mg ii outflow velocities and low Mg ii column densities trace low-density H i channels that facilitate LyC escape.}, archive = {J_ApJ}, author = {Zhihui Li and Max Gronke and Timothy Heckman and Xinfeng Xu and Alaina Henry and Cody Carr and John Chisholm and Sanchayeeta Borthakur and Rui Marques-Chaves and Daniel Schaerer and Floriane Leclercq and Danielle A. Berg}, doi = {10.3847/1538-4357/adf441}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {49}, shortjournal = {The Astrophys. J.}, title = {Synergistic radiative transfer modeling of mg II and lyα emission in multiphase, clumpy galactic environments: Application to low-redshift lyman continuum leakers}, volume = {991}, year = {2025}, }
• (2025). Correcting for interloper contamination in the power spectrum with neural networks. ApJ, 991(1), 48. (www)

  @article{ , abstract = {Modern slitless spectroscopic surveys such as Euclid and Roman collect vast numbers of galaxy spectra, but their low signal-to-noise ratios often lead to incorrect redshift assignments when relying on a single emission line. This misidentification, commonly caused by noise spikes or nontarget emission-line contamination, results in redshift interlopers . We present a machine learning method to mitigate interloper effects at the level of cosmological summary statistics, focusing on the power spectrum monopole as a test case. Using halo catalogs from the Quijote simulations as galaxy proxies, we simulate interlopers by displacing a fraction of halos by redshift offsets between target and interloper populations. This yields contaminated catalogs spanning a wide cosmological parameter space. We train a neural network on the power spectrum monopole, alone or combined with the bispectrum monopole, from contaminated mocks to estimate the interloper fraction and reconstruct the cleaned power spectrum. We assess performance in two scenarios: one with fixed cosmology and one where cosmological parameters vary. In the fixed case, the method recovers the interloper fraction and corrects the power spectrum to 1% accuracy. When cosmology varies, performance degrades, but including bispectrum information improves results, reducing interloper fraction errors and correcting with 2% accuracy. We also analyze how the size of the training set and the correlation between target and interloper populations affect performance. When these samples are uncorrelated, bispectrum information is more beneficial; when strongly correlated, tighter cosmological priors offer greater improvements. Our results demonstrate the potential of machine learning to enhance cosmological inference in contaminated spectroscopic data sets.}, archive = {J_ApJ}, author = {Marina S. Cagliari and Azadeh Moradinezhad Dizgah and Francisco Villaescusa-Navarro}, doi = {10.3847/1538-4357/adf72a}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {48}, shortjournal = {The Astrophys. J.}, title = {Correcting for interloper contamination in the power spectrum with neural networks}, volume = {991}, year = {2025}, }
• (2025). Subparsec jet morphologies of m87 at 43 GHz: Effects of asymmetric plasmoids within the jet. ApJ, 991(1), 47. (www)

  @article{ , abstract = {Radio observations of the M87 jet reveal limb-brightened features that exhibit temporal variations, with the brighter limb side not remaining consistently fixed at the subparsec scales. Utilizing a force-free jet model that considers exclusively the relativistic plasma dynamics along large-scale magnetic fields attached onto the central black hole, we examine the effects of asymmetric plasmoid injections within the subparsec jet. At subparsec scales, the jet velocity is predominantly influenced by poloidal velocity, leading to distinctive characteristics in both the morphology and trajectories of the plasmoids injected within the jet. We explore the potential modifications to the limb-brightened subparsec jet images resulting from the injection of asymmetric, shearing plasma, which is traditionally considered solely under conditions of stationary and symmetric mass loading. By comparing the model jet properties with the 43 GHz observations of the M87 jet, it is suggested that the asymmetric injection of plasmoids within the jet offers a satisfactory explanation for the observed velocity variations and morphological dynamics of the M87 jet.}, archive = {J_ApJ}, author = {Guan-Hong Li and Hung-Yi Pu}, doi = {10.3847/1538-4357/adf733}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {47}, shortjournal = {The Astrophys. J.}, title = {Subparsec jet morphologies of m87 at 43 GHz: Effects of asymmetric plasmoids within the jet}, volume = {991}, year = {2025}, }
• (2025). Calculation of a dynamical substitute for the real Earth–Moon system based on hamiltonian analysis. ApJ, 991(1), 46. (www)

  @article{ , abstract = {The Earth–Moon libration points no longer exhibit the dynamical characteristics of “equilibrium points” due to perturbation effects when applying the ephemeris model. By decoupling the forced motions within the ephemeris model and computing the dynamical substitute trajectories, we can reconstruct a dynamical system that recovers the “equilibrium points” feature. Diverging from the conventional analytical approach rooted in the framework of Newtonian mechanics, this paper presents a novel method for calculating dynamical substitute based on the Hamiltonian mechanics framework. First, the Hamiltonian equations for the ephemeris model are formulated. Subsequently, the problem of decoupling forced motions is reformulated as solving a nonautonomous differential equation through canonical transformations. Then, an iterative method based on frequency analysis is employed for the computation. Eventually, approximate analytical solutions for five libration points over a 360 yr period are provided. Simulation results demonstrate that the computed approximate analytical solutions are in excellent agreement with the numerical integration results derived from the ephemeris model, thereby validating the efficacy of the proposed method. The Hamiltonian dynamical system derived herein enables the analysis of nonlinear central manifold motions via canonical transformations, facilitating the construction of higher-order analytical solutions for libration point orbits. This framework also provides a robust foundation for exploring characterization parameters of libration point orbits within the real Earth–Moon system.}, archive = {J_ApJ}, author = {Chenyuan Qiao and Xi Long and Leping Yang and Yanwei Zhu and Weiwei Cai}, doi = {10.3847/1538-4357/adf73a}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {46}, shortjournal = {The Astrophys. J.}, title = {Calculation of a dynamical substitute for the real Earth–Moon system based on hamiltonian analysis}, volume = {991}, year = {2025}, }
• (2025). Molecular jets from an evolved protostar: Insights from JWST-ALMA synergy. ApJ, 991(1), 45. (www)

  @article{ , abstract = {The combination of the Atacama Large Millimeter/submillimeter Array (ALMA) and JWST/MIRI mid-infrared observations offers a transformative view of protostellar jets and outflows by probing cold and warm gas components across diverse physical conditions. We present a detailed comparison of gas distribution in these regimes for the jet/outflow system associated with G205.46−14.56S3 (HOPS 315), focusing on the inner ∼800 au along the jet. ALMA CO and SiO trace both lobes of the bipolar jet, revealing high-velocity collimated jets and wider outflow components. JWST/MIRI detects mainly the blueshifted lobe; the redshifted side is likely obscured by strong mid-infrared extinction. Shorter-wavelength MIRI H 2 rotational lines (S(7)–S(4)) trace compact jet structures resembling SiO emission, while longer-wavelength lines (S(3)–S(1)) reveal more extended emission akin to low-velocity CO. From H 2 rotational emission, we identify two molecular gas temperature components: warm (∼773 ± 44 K) and hot (∼2499 ± 721 K). Using the ortho-to-para ratio, we estimate visual extinction A V ≈ 23.3 ± 2.5 mag. JWST/MIRI emission implies a jet mass-loss rate of {\dot{M}}_{{\rm{J}},{\rm{blue}},{\rm{jwst}}}\approx (0.27\pm 0.1)\times 1{0}^{-6}\,{M}_{\odot }\,{{\rm{yr}}}^{-1} . The combination of ALMA and JWST reveals stratified layers within the outflow and jet, as well as shock structures, providing a comprehensive view of their physical conditions. This multiwavelength study demonstrates that combining submillimeter observations from ALMA with infrared data from JWST is crucial for uncovering the full physical and chemical structure of protostellar jets and outflows.}, archive = {J_ApJ}, author = {Somnath Dutta}, doi = {10.3847/1538-4357/adf8d6}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {45}, shortjournal = {The Astrophys. J.}, title = {Molecular jets from an evolved protostar: Insights from JWST-ALMA synergy}, volume = {991}, year = {2025}, }
• (2025). Millisecond pulsars in m2: New discoveries and a detailed timing analysis. ApJ, 991(1), 44. (www)

  @article{ , abstract = {Globular clusters (GCs) offer a unique environment for discovering and studying millisecond pulsars. In this paper, we present a multiepoch search and detailed timing analysis of millisecond pulsars in the GC M2, using the Five-hundred-meter Aperture Spherical radio Telescope. We have discovered two new binary millisecond pulsars in M2, designated M2F and M2G. We provide measurements of the emission properties of all known pulsars in M2, including their polarization profiles, rotation measures (RMs), flux densities, scintillation characteristics, and so forth. In particular, we report the first RM at the distance and direction of this cluster. Additionally, we report the first phase-coherent timing solutions for the M2 pulsars. From our Bayesian timing analysis, we have measured their spin and orbital parameters with high precision, including the advance of periastron for M2A and M2E indicating total system masses of 1.75(13) and 1.80(5) solar masses, respectively. Using archival data from the Hubble Space Telescope, we have identified an optical counterpart of M2C, which is likely the white dwarf companion of the pulsar. By combining results from optical and radio observations, we have reconstructed the binary evolution track of this system and estimated the cooling age of the companion to be approximately 10 Myr, making it the youngest white dwarf in any known GC binary pulsars. Furthermore, using the spin period derivatives of M2 pulsars, we have investigated the gravitational potential of the cluster and found that our results strongly support the latest central stellar velocity dispersion measurement in M2.}, archive = {J_ApJ}, author = {Baoda Li and Kuo Liu and Lin Wang and Shunyi Lan and P. C. C. Freire and Pinsong Zhao and Liyun Zhang and Zhengwei Liu and Lei Qian and Wu Jiang and Dejiang Yin and Yaowei Li and Yinfeng Dai and Yang Liu and Xiangcun Meng and Zhichen Pan}, doi = {10.3847/1538-4357/adf969}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {44}, shortjournal = {The Astrophys. J.}, title = {Millisecond pulsars in m2: New discoveries and a detailed timing analysis}, volume = {991}, year = {2025}, }
• (2025). X-ray studies of PSR j1838–0655 and its wind nebula associated with HESS j1837–069 and 1LHAASO j1837–0654u. ApJ, 991(1), 43. (www)

  @article{ , abstract = {We analyzed X-ray data from Chandra, XMM-Newton, NICER, and NuSTAR to characterize the properties of the pulsar PSR J1838−0655 and its pulsar wind nebula (PWN) associated with HESS J1837−069. Based on 5.5 yr of NICER monitoring, we detected a glitch around MJD 59300, characterized by a fractional frequency jump of approximately 2 × 10 −6 . We constructed semi-phase-coherent timing solutions for pre- and postglitch epochs, allowing for phase alignment of multi-instrument data and a subsequent measurement of the pulsed spectrum of the pulsar. This analysis confirmed previously reported spectral curvature and revealed a peak energy of 7{3}_{-26}^{+85} keV in the pulsar’s spectral energy distribution (SED), based on a logpar model fit of the pulsed spectrum. We discuss these findings within the framework of pulsar magnetospheric emission scenarios. The PWN’s X-ray spectrum is well described by a power law with a photon index of 2.1 ± 0.3, softer than previously reported measurements. We also characterized the X-ray emission from another extended X-ray source AX J1837.3−0652 within the extent of HESS J1837−069. Based on the spatial and spectral properties of these X-ray sources, we propose a leptonic emission scenario for HESS J1837−069 and demonstrate its feasibility through SED modeling. Finally, we discuss the implications of our model results and alternative scenarios for the gamma-ray emission.}, archive = {J_ApJ}, author = {Minseo Park and Jaegeun Park and Chanho Kim and Hongjun An}, doi = {10.3847/1538-4357/adfa08}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {43}, shortjournal = {The Astrophys. J.}, title = {X-ray studies of PSR j1838–0655 and its wind nebula associated with HESS j1837–069 and 1LHAASO j1837–0654u}, volume = {991}, year = {2025}, }
• (2025). On the origin of super-global spin-up trends of X-ray pulsars in HMXB systems. ApJ, 991(1), 42. (www)

  @article{ , abstract = {Most X-ray pulsars in high-mass X-ray binary (HMXB) systems exhibit both global and local trends of spin acceleration (spin-up) and deceleration (spin-down). Moreover, decades-long monitored objects display even more general spin-up trends in their spin evolution and simultaneously demonstrate a decrease in the orbital period, so-called orbital decay. Although obvious, this general behavior leaves open the question of the energy source and the mechanism of angular momentum transfer that ensures the neutron star’s (NS's) spin acceleration. We hypothesize that the observed spin acceleration of X-ray pulsars in HMXB (Roche lobe overflow and sgXRB) systems results from orbital angular momentum transfer via tidal interactions with their massive companions. To study these phenomena, we sample five well-studied objects with the longest observational history of their spin periods from the population of known Galactic persistent X-ray pulsars in HMXB systems. We obtain the spin frequency change from the observational data and estimate energy loses for orbital decay and pulsars’ spin acceleration. We propose a new term of super-global spin-up trends, and show that their observable values do not exceed theoretical upper limits predicted within the scenario of orbital decay due to the tidal interaction between the NS and its massive companion.}, archive = {J_ApJ}, author = {Vitaliy Kim and Yerlan Aimuratov}, doi = {10.3847/1538-4357/adfa96}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {42}, shortjournal = {The Astrophys. J.}, title = {On the origin of super-global spin-up trends of X-ray pulsars in HMXB systems}, volume = {991}, year = {2025}, }
• (2025). Asymmetric tangential velocity inside switchbacks: Implication for switchback origin. ApJ, 991(1), 41. (www)

  @article{ , abstract = {Switchbacks are structures in the solar wind marked by large rotations in the magnetic field direction without significant changes in its magnitude, typically accompanied by enhanced bulk speed. Parker Solar Probe (PSP) measurements have established the switchback as a prominent feature of the near-Sun solar wind. Detailed observations have shed light on switchback properties, leading to various proposed mechanisms for their generation. However, one key aspect that remains unexplored is the distribution of the tangential bulk velocity within switchbacks. A particular challenge has been accurately determining the tangential component of the plasma flow in the near-Sun plasma. With the most recent Solar Probe Cup measurements, it has been possible to gather sufficient statistics of proton tangential speed data in near-Sun solar wind switchbacks. This is important because some switchback models, particularly those involving solar wind interactions, predict that the tangential velocity should exhibit a strong one-sided polarity inside switchbacks. In this study, we examine the tangential component of the bulk velocity inside switchbacks during PSP encounters. Our findings reveal that switchbacks preferentially exhibit a positive tangential bulk velocity, strongly supporting the hypothesis that the majority of switchbacks are generated by the interaction of slow and fast wind across a superspiral outside the Alfvén critical point.}, archive = {J_ApJ}, author = {R. Bandyopadhyay and J. Ward and D. J. McComas and N. A. Schwadron and S. Badman and K. Paulson and M. Stevens}, doi = {10.3847/1538-4357/adfc45}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {41}, shortjournal = {The Astrophys. J.}, title = {Asymmetric tangential velocity inside switchbacks: Implication for switchback origin}, volume = {991}, year = {2025}, }
• (2025). Magnetohydrodynamic study of mars’s response to short-term solar wind dynamic pressure enhancements. ApJ, 991(1), 40. (www)

  @article{ , abstract = {As a weakly magnetized planet, Mars interacts directly with the highly variable solar wind, where small-scale and short-duration structures are ubiquitous. Among solar wind parameters, dynamic pressure, as the dominant external pressure, plays a key role in shaping the pressure level and structures in the downstream induced magnetosphere. In this study, a multispecies global magnetohydrodynamic model is used to investigate Mars’s response to a series of idealized solar wind dynamic pressure enhancements with varying durations and magnitudes, aiming to capture responses in different plasma regions and isolate the effects of dynamic pressure. For the subsolar region, the simulations reveal a sequence of response phases, each exhibiting distinct temporal characteristics. Beyond the subsolar region, the terminator ionosphere and global ion escape show prolonged disturbances. These results highlight the importance of short-term upstream variability in shaping both local and global features of the Martian plasma environment and provide context for interpreting spacecraft observations that sample only limited regions of the system.}, archive = {J_ApJ}, author = {Wenyi Sun and Yingjuan Ma and Christopher T. Russell and Janet Luhmann and David Brain}, doi = {10.3847/1538-4357/adfc6b}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {40}, shortjournal = {The Astrophys. J.}, title = {Magnetohydrodynamic study of mars’s response to short-term solar wind dynamic pressure enhancements}, volume = {991}, year = {2025}, }
• (2025). Size distributions of arcsecond-scale properties of solar flare ribbons. ApJ, 991(1), 39. (www)

  @article{ , abstract = {Solar flare ribbons are believed to map the footpoints of newly reconnected magnetic flux tubes; therefore, shedding light on the reconnecting current sheet, which is rarely observed by direct imaging or spectroscopy. Here we study the detailed evolution of flare ribbons down to the arcsecond scale for 10 flares characterized by the classic double ribbons. Identifying the flaring pixels by combining the intensity variances of the UV filter ratio and an intensity threshold, we found that the waiting time distributions of the flaring pixels are well described by power laws, distinct from those in the preflare or quiet-Sun regions, and that the power-law slopes are generally consistent with those predicted by nonstationary Poisson processes in the nonlinear regime or by the 2D/3D self-organized criticality (SOC) model. The size distributions for flaring duration also follow power laws but the slopes are more scattered. In contrast, the size distributions for other parameters, including peak intensity, energy, and radial magnetic field strength of the flaring pixels, deviate from power laws, and the estimated slopes significantly differ from the SOC predictions. These results suggest that a nonstationary Poisson process or an avalanche-like process might be ongoing temporally in the reconnecting current sheet, but in other aspects, e.g., space- and energy-wise, the avalanche is likely modulated by other physical processes or the fine structures of the reconnecting current sheet.}, archive = {J_ApJ}, author = {Yue Zhang and Rui Liu and Wensi Wang and Junyan Liu}, doi = {10.3847/1538-4357/adfcd3}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {39}, shortjournal = {The Astrophys. J.}, title = {Size distributions of arcsecond-scale properties of solar flare ribbons}, volume = {991}, year = {2025}, }
• (2025). Searching for pulsars in globular clusters with the fast-folding algorithm and a new pulsar discovered in m13. ApJ, 991(1), 38. (www)

  @article{ , abstract = {We employed the fast-folding algorithm on L -band globular cluster (GC) observations taken with the Five-hundred-meter Aperture Spherical radio Telescope to search for new pulsars, especially those with a long rotational period. We conducted a search across 16 GCs that collectively host 93 known pulsars, as well as 14 GCs that do not contain any known pulsars. The majority of these known pulsars were successfully redetected in our survey. The few nondetections could be attributed to the high accelerations of these pulsars. Additionally, we have discovered a new binary millisecond pulsar, namely M13I (or PSR J1641+3627I) in GC M13 (or NGC 6205), and obtained its phase-coherent timing solution using observations spanning 6 yr. M13I has a spin period of 6.37 ms and an orbital period of 18.23 days. The eccentricity of the binary orbit is 0.064, with a companion mass range of approximately 0.45 to 1.37 M ⊙ . The orbital properties of M13I are remarkably different from those of the other known pulsars in M13, indicating that this pulsar has undergone a different evolutionary path compared to the rest.}, archive = {J_ApJ}, author = {Yaowei Li and Lin Wang and Lei Qian and Liyun Zhang and Yujie Chen and Dejiang Yin and Baoda Li and Yinfeng Dai and Ralph P. Eatough and Wenze Li and Dongyue Jiang and Xingnan Zhang and Minghui Li and Yujie Lian and Yuxiao Wu and Tong Liu and Kuo Liu and Zhichen Pan}, doi = {10.3847/1538-4357/add6a5}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {38}, shortjournal = {The Astrophys. J.}, title = {Searching for pulsars in globular clusters with the fast-folding algorithm and a new pulsar discovered in m13}, volume = {991}, year = {2025}, }
• (2025). COSMOS-web: The overabundance and physical nature of “Little red Dots”—Implications for early galaxy and SMBH assembly. ApJ, 991(1), 37. (www)

  @article{ , abstract = {JWST has revealed a population of compact and extremely red galaxies at z ≳ 4, which likely host active galactic nuclei (AGNs). We present a sample of 434 “little red dots” (LRDs), selected from the 0.54 deg 2 COSMOS-Web survey. We fit galaxy and AGN spectral energy distribution models to derive redshifts and physical properties; the sample spans z ∼ 5–9 after removing brown dwarf contaminants. As a thought experiment, we consider two extreme physical scenarios: either LRDs are all AGNs, and their continuum emission is dominated by the accretion disk, or they are all compact star-forming galaxies, and their continuum is dominated by stars. If LRDs are AGN-dominated, our sample exhibits bolometric luminosities ∼10 45−47 erg s −1 , spanning the gap between JWST AGNs in the literature and bright, rare quasars. We derive a bolometric luminosity function (LF) ∼ 100 times the (UV-selected) quasar LF, implying a nonevolving black hole accretion density of ∼10 −4 M ⊙ yr −1 Mpc −3 from z ∼ 2–9. By contrast, if LRDs are dominated by star formation, we derive stellar masses ∼10 8.5−10 M ⊙ . MIRI/F770W is key to deriving accurate stellar masses; without it, we derive a mass function inconsistent with Λ cold dark matter. The median stellar mass profile is broadly consistent with the maximal surface densities seen in the nearby Universe, though the most massive objects exceed this limit, requiring substantial AGN contribution to the continuum. Nevertheless, stacking all available X-ray, mid-IR, far-IR/submillimeter, and radio data yields nondetections. Whether dominated by dusty AGNs or compact star-formation, the high masses/luminosities and remarkable abundance of LRDs implies a dominant mode of early galaxy/SMBH growth.}, archive = {J_ApJ}, author = {Hollis B. Akins and Caitlin M. Casey and Erini Lambrides and Natalie Allen and Irham T. Andika and Malte Brinch and Jaclyn B. Champagne and Olivia Cooper and Xuheng Ding and Nicole E. Drakos and Andreas Faisst and Steven L. Finkelstein and Maximilien Franco and Seiji Fujimoto and Fabrizio Gentile and Steven Gillman and Ghassem Gozaliasl and Santosh Harish and Christopher C. Hayward and Michaela Hirschmann and Olivier Ilbert and Jeyhan S. Kartaltepe and Dale D. Kocevski and Anton M. Koekemoer and Vasily Kokorev and Daizhong Liu and Arianna S. Long and Henry Joy McCracken and Jed McKinney and Masafusa Onoue and Louise Paquereau and Alvio Renzini and Jason Rhodes and Brant E. Robertson and Marko Shuntov and John D. Silverman and Takumi S. Tanaka and Sune Toft and Benny Trakhtenbrot and Francesco Valentino and Jorge Zavala}, doi = {10.3847/1538-4357/ade984}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {37}, shortjournal = {The Astrophys. J.}, title = {COSMOS-web: The overabundance and physical nature of “Little red Dots”—Implications for early galaxy and SMBH assembly}, volume = {991}, year = {2025}, }
• (2025). Watching our galaxy grow up: The mass and color evolution of the milky way. ApJ, 991(1), 36. (www)

  @article{ , abstract = {Using our rich observations within the Milky Way to better understand galaxy evolution requires understanding what the Milky Way looks like “as a galaxy”—that is, its “true” shape and abundance profiles (unskewed by observational biases), signatures of past mergers and significant accretion events, and even its total stellar mass and integrated spectral energy distribution, which have historically been difficult to constrain. We present a new approach to determining the Milky Way’s integrated mass and colors, using recent measurements of the intrinsic density profiles of stellar populations spanning nearly 13 Gyr in time and 1.5 dex in metallicity (representing nearly all of the Galaxy’s stars). We trace the evolution of the Milky Way in various diagnostic spaces, explore the impact of specific events on the present-day Milky Way’s integrated properties, and use TNG50 simulations to identify “young” Galactic analogs and their eventual fates, compared to the real Milky Way’s path. From the simulation comparisons, we find strong evidence for an earlier-than-average stellar mass assembly of the Milky Way, and that present-day Milky Way analogs follow a similar growth history, albeit at slightly later times; we also find that analogs of the early Milky Way are in no way guaranteed to follow the Milky Way's subsequent path. This empirical study offers new constraints on our “Galaxy as a galaxy”—today and across cosmic time—and on its place in the general galactic population.}, archive = {J_ApJ}, author = {Gail Zasowski and Julie Imig and Hayley Coluccio}, doi = {10.3847/1538-4357/adef53}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {36}, shortjournal = {The Astrophys. J.}, title = {Watching our galaxy grow up: The mass and color evolution of the milky way}, volume = {991}, year = {2025}, }
• (2025). Identifying a protocluster formation at z ∼ 4.5 in the COSMOS field: An extension of the taralay protocluster, traced by lyα emitters surrounding a submillimeter galaxy. ApJ, 991(1), 35. (www)

  @article{ , abstract = {We report the discovery of a large-scale structure containing multiple overdensities at z = 4.54 ± 0.03 in the COSMOS field, with the most prominent one likely infalling toward the recently identified Taralay protocluster. We use combined wideband and narrowband (NB) optical photometry to identify Ly α emitters (LAEs) within a 21 cMpc radius from the submillimeter source J1000+0234, at z = 4.54, to identify typical star-forming galaxies that may trace an underlying structure. Our approach selects line emitters as NB excess objects and we use the COSMOS2020 photometric redshift catalog to eliminate potential low-redshift interlopers whose line emission (e.g., [O III ] at z ∼ 0.3) might be responsible for the observed excess in the narrow band. In comparison with the LAE density in the field, our results point to a mean LAE number overdensity of \bar{\delta }=3 spanning a region of 27 × 20 × 36 cMpc 3 , probably evolving into a moderate-mass cluster ((3–10) × 10 14 M ⊙ ) at z ∼ 0. This work supports the idea that submillimeter sources, although offset from the major overdensity peaks, serve as traces of moderately massive, potentially infalling structures.}, archive = {J_ApJ}, author = {Mariana Rubet and Karín Menéndez-Delmestre and T. S. Gonçalves and F. Almeida-Fernandes and L. Santana-Silva and Peter L. Capak and Kartik Sheth}, doi = {10.3847/1538-4357/adf18c}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {35}, shortjournal = {The Astrophys. J.}, title = {Identifying a protocluster formation at z ∼ 4.5 in the COSMOS field: An extension of the taralay protocluster, traced by lyα emitters surrounding a submillimeter galaxy}, volume = {991}, year = {2025}, }
• (2025). Are local group dwarf spheroidal galaxies the first safe planet-hosting environments?. ApJ, 991(1), 34. (www)

  @article{ , abstract = {We explore whether Local Group dwarf spheroidal (dSph) galaxies might have hosted Earth-like planets dwelling unexposed for several billions of years to major galactic threats to life, such as supernovae and gamma-ray bursts. To this aim, we developed a novel semiempirical model that exploits the observed chemical abundances and star formation histories of a selected sample of local dSphs, to explore whether their stars may have (i) reached the minimum metallicity to trigger planet formation and (ii) avoided exposure to destructive events long enough to provide time for possible biological development. From our work two scenarios emerge. If planet formation is possible for [Fe/H] ≲ −1, then in all dSphs with 5 × 10 3 L ⊙ ≤ L V ≤ 2 × 10 7 L ⊙ a fraction ≈0.1%–10% of stars might have safely hosted terrestrial planets for more than 1 Gyr. In this scenario, ancient ultrafaint dwarf galaxies (UFDs, L V ≤ 10 5 L ⊙ ) would have been the first to reach this condition in the history of the Local Group. Conversely, if planets form for [Fe/H] ≥ −0.6 then they should not exist in UFDs, while only ≈0.001%–0.1% of stars in dSphs with L V ≥ 3 × 10 5 L ⊙ would host planets dwelling in safe conditions for long times. Interestingly, we find a “luminosity sweet spot” at L V ∼ 10 6 L ⊙ , where dSphs in our sample safely host terrestrial planets up to 4 Gyr and in any planet formation scenario explored. In conclusion, planet formation at low metallicity is key to understanding which types of galaxies might have formed Earth-like planets that dwelt unexposed to galactic threats over several billions of years, first in the history of the Local Group.}, archive = {J_ApJ}, author = {Stefano Ciabattini and Stefania Salvadori and Leonardo Testi}, doi = {10.3847/1538-4357/adf4c0}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {34}, shortjournal = {The Astrophys. J.}, title = {Are local group dwarf spheroidal galaxies the first safe planet-hosting environments?}, volume = {991}, year = {2025}, }
• (2025). Extreme jet beaming observed in neutrino-associated blazars. ApJ, 991(1), 33. (www)

  @article{ , abstract = {Bright blazars were found to be prominent neutrino sources, and a number of IceCube events were associated with them over recent years. A particularly strong observational connection is present between neutrinos and blazars with bright, Doppler-boosted, parsec-scale radio emission. In this work, we further explore the nature of this connection by examining the jet geometry and kinematics of neutrino-associated blazars. We find that these blazars demonstrate remarkably strong jet beaming, even compared to other radio-bright sources. Their Doppler and Lorentz factors are larger, and viewing angles are smaller than for other blazars in the complete uniformly selected MOJAVE sample. Observationally, this serves as yet another piece of evidence for blazars forming a major population of neutrino sources. The strong neutrino–beaming correlation indicates that high-energy neutrino velocity is predominantly oriented along the jet, and the original PeV-scale protons exhibit a relativistic bulk motion along the jet. It suggests that neutrino production happens not too close to the black hole, but rather at subparsec distances, where the jet is already accelerated.}, archive = {J_ApJ}, author = {A. V. Plavin and Y. Y. Kovalev and S. V. Troitsky}, doi = {10.3847/1538-4357/adf54f}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {33}, shortjournal = {The Astrophys. J.}, title = {Extreme jet beaming observed in neutrino-associated blazars}, volume = {991}, year = {2025}, }
• (2025). Unveiling the cosmic gems arc at z ∼ 10 with JWST NIRCam. ApJ, 991(1), 32. (www)

  @article{ , abstract = {We present recent JWST NIRCam imaging observations of SPT0615-JD (also known as the Cosmic Gems Arc), lensed by the galaxy cluster SPT-CL J0615−5746. The 5 ″ long arc is the most highly magnified z > 10 galaxy known. It straddles the lensing critical curve and reveals five star clusters with radii of ∼1 pc or less. We measure the full arc to have F200W 24.5 AB mag, consisting of two mirror images, each 25.3 AB mag with a median magnification of \mu \sim 6{0}_{-8}^{+17} (delensed 29.7 AB mag, M UV = −17.8). The galaxy has an extremely strong Lyman break F115W−F200W >3.2 mag (2 σ lower limit), is undetected in all bluer filters (<2 σ ), and has a very blue continuum slope redward of the break ( β = −2.7 ± 0.1). This results in a photometric redshift z phot = 10.2 ± 0.2 (95% confidence) with no significant likelihood below z < 9.8. Based on spectral energy distribution fitting to the total photometry, we estimate an intrinsic stellar mass of M * ∼ 2.4–5.6 × 10 7 M ⊙ , young mass-weighted age of ∼21–79 Myr, low dust content ( A V < 0.15), and a low metallicity of ≲1% Z ⊙ . We identify a fainter third counterimage candidate within 2 \mathop{.}\limits{^{\prime\prime} } 2 of the predicted position, lensed to AB mag 28.4 and magnified by μ ∼ 2, suggesting the fold arc may only show ∼60% of the galaxy. SPT0615-JD is a unique laboratory to study star clusters observed within a galaxy just 460 Myr after the Big Bang.}, archive = {J_ApJ}, author = {Larry D. Bradley and Angela Adamo and Eros Vanzella and Keren Sharon and Gabriel Brammer and Dan Coe and Jose M. Diego and Vasily Kokorev and Guillaume Mahler and Masamune Oguri and Abdurro’uf and Rachana Bhatawdekar and Lise Christensen and Seiji Fujimoto and Takuya Hashimoto and Tiger Y.-Y Hsiao and Akio K. Inoue and Yolanda Jiménez-Teja and Matteo Messa and Colin Norman and Massimo Ricotti and Yoichi Tamura and Rogier A. Windhorst and Xinfeng Xu and Adi Zitrin}, doi = {10.3847/1538-4357/adf638}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {32}, shortjournal = {The Astrophys. J.}, title = {Unveiling the cosmic gems arc at z ∼ 10 with JWST NIRCam}, volume = {991}, year = {2025}, }
• (2025). Kinematical modeling of the resolved stellar outskirts of m32: Constraints on tidal stripping scenarios. ApJ, 991(1), 31. (www)

  @article{ , abstract = {As the only compact elliptical close enough to resolve into individual stars, the satellite dwarf galaxy M32 provides a unique opportunity for exploring the origins of such rare galaxies. In this work, we combined archival and novel Keck/DEIMOS spectroscopy from a southern extension of the Spectroscopic and Photometric Landscape of Andromeda’s Stellar Halo (SPLASH) survey with optical HST imaging from the Panchromatic Hubble Andromeda Southern Treasury (PHAST) survey. The resulting sample of 2505 giant stars is unprecedented both in size and spatial coverage (0 \mathop{.}\limits{{{\rm{^{\prime}} }}} 9–15 \mathop{.}\limits{{{\rm{^{\prime}} }}} 5, or out to ∼23 r eff and ∼30 r eff along M32’s major and minor axes) for probing the resolved stellar outskirts of M32. Given the structurally complex region near M32 on the sky, we modeled M32’s line-of-sight kinematics simultaneously alongside M31’s rotating stellar disk and potential outliers corresponding to M31’s kinematically hot stellar halo and/or tidal substructure. Inside the radius corresponding to the observed twisting of isophotal contours in M32’s surface brightness profile ( R iso ∼ 5 r eff ∼ 150” or 0.56 kpc), M32 exhibits a line-of-sight velocity distribution characteristic of ordered rotation, transitioning to a distribution with heavier outliers beyond this radius. Within R iso , the rotational direction is aligned with M32’s major-axis rotation, but shifts to become roughly aligned with M32’s minor axis beyond R iso . We interpret these kinematical signatures in the stellar outskirts of M32 as evidence of tidal distortion from interactions with M31 and discuss their implications for M32 formation pathways.}, archive = {J_ApJ}, author = {Ivanna Escala and Douglas Grion Filho and Puragra Guhathakurta and Karoline M. Gilbert and Mark Fardal and L. R. Cullinane and Erik Tollerud and Amanda C. N. Quirk and Zhuo Chen and Molly Hyver and Benjamin F. Williams}, doi = {10.3847/1538-4357/adf63c}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {31}, shortjournal = {The Astrophys. J.}, title = {Kinematical modeling of the resolved stellar outskirts of m32: Constraints on tidal stripping scenarios}, volume = {991}, year = {2025}, }
• (2025). Tracing red giant members of the globular cluster palomar 5 with APOGEE and gaia. ApJ, 991(1), 30. (www)

  @article{ , abstract = {The globular cluster Palomar 5 (Pal 5) is in the process of being tidally shredded as it orbits the Milky Way. Its core is currently at a heliocentric distance of ∼21 kpc, near apogalacticon (∼18 kpc), and it reaches ∼5–7 kpc at perigalacticon. Pal 5’s leading and trailing arms stretch over 20° on the sky, making them sensitive probes of the Milky Way’s mass distribution. In this work, we search for red giant members of Pal 5 using spectroscopic data from APOGEE DR17 and photometric and astrometric data from Gaia data release 3. Based on position and proper motion, we identify eight members of Pal 5: six in the core and two in the stream. The clustering algorithm HDBSCAN finds these same eight. We then use chemical tagging with APOGEE abundances to search for additional members across five APOGEE fields overlapping Pal 5. While several dozen candidates are identified, most deviate (some significantly) from known kinematic and color–magnitude trends, suggesting that they are less likely to be true members. We estimate the expected number of giants in the APOGEE pointings based on the area and stellar mass of the streams. Given APOGEE’s limiting magnitude, we find that few, if any, new giants are expected, especially if the stream is more diffuse at these locations. Our results support the presence of density variations in Pal 5’s tidal streams, consistent with earlier studies attributing such features to baryonic perturbers in the Milky Way, dark matter subhalos, or interactions with passing globular clusters.}, archive = {J_ApJ}, author = {Allyson A. Sheffield and Sarah Pearson and Lenin F. Nolasco and Rachael L. Beaton and Adrian M. Price-Whelan and Rafael Guerço and Katia Cunha and Verne V. Smith}, doi = {10.3847/1538-4357/adf645}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {30}, shortjournal = {The Astrophys. J.}, title = {Tracing red giant members of the globular cluster palomar 5 with APOGEE and gaia}, volume = {991}, year = {2025}, }
• (2025). Numerical approach to compressible shallow-water dynamics of neutron-star spreading layers. ApJ, 991(1), 29. (www)

  @article{ , abstract = {A weakly magnetized neutron star (NS) undergoing disk accretion should release about half of its power in a compact region known as the accretion boundary layer. Latitudinal spread of the accreted matter and efficient radiative cooling justify the approach to this flow as a two-dimensional spreading layer (SL) on the surface of the star. Numerical simulations of SLs are challenging because of the curved geometry and supersonic nature of the problem. We develop and test a new two-dimensional hydrodynamics code, SPLASH , which uses the multislope second-order Monotonic Upstream-centered Scheme for Conservation Law scheme in combination with an HLLC+ Riemann solver on an arbitrary irregular mesh on a spherical surface. The code is suitable and accurate for Mach numbers up to 5–10. Adding sinks and sources to the conserved variables, we simulate early stages of constant-rate accretion onto a spherical NS. During these stages of accretion, heating in the equatorial region triggers convective instability that causes rapid mixing in the latitudinal direction. One of the outcomes of the instability is the development of a “tennis ball” pattern rotating at a frequency considerably different from the rotation frequency of the matter. In the simulated variability curves, there are signatures of both the pattern rotation and the rotation of the SL, as well as their harmonics. The pattern and cyclonal vortices associated with it are probably a manifestation of an inertial oscillation mode excited within the layer ( https://github.com/TURBOLOSE/SPLASH ).}, archive = {J_ApJ}, author = {Aleksandr Rusakov and Pavel Abolmasov and Omer Bromberg}, doi = {10.3847/1538-4357/adf6a8}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {29}, shortjournal = {The Astrophys. J.}, title = {Numerical approach to compressible shallow-water dynamics of neutron-star spreading layers}, volume = {991}, year = {2025}, }
• (2025). Multiwavelength study of HESS j0632+057: New insights into Pulsar–Disk interaction. ApJ, 991(1), 28. (www)

  @article{ , abstract = {We present an analysis of new multiwavelength observations of the TeV gamma-ray binary HESS J0632+057, conducted using SALT, Swift, NuSTAR, and VERITAS in 2023–2024. By combining these new data with archival observations, we confirm previous suggestions of orbital variability in the source’s X-ray spectrum, including increased X-ray absorption at the orbital phase interval of ϕ ≈ 0.3–0.4. The source’s X-ray flux within this phase interval seems to have exhibited a significant change on an orbital timescale. Additionally, occasional short-term variations in the X-ray band on a timescale of less than 3 days have been observed. The measured duration of the increased absorbing column density and the flux variability timescales can provide clues about the interaction between the putative pulsar and the Be companion’s disk if, as previously suggested, the pulsar crosses the disk at this phase interval. Moreover, the new contemporaneous X-ray and TeV observations around the pulsar-crossing phases revealed independent variability in the X-ray and TeV fluxes, contrary to a previous observation of concurrent flux increases. While these observations alone cannot provide definitive conclusions, we discuss our results in the context of pulsar–disk interaction and intrabinary shock emission scenarios.}, archive = {J_ApJ}, author = {Jaegeun Park and Hongjun An and Chanho Kim and Natalie Matchett and Kaya Mori and Brian van Soelen and A. Archer and P. Bangale and J. T. Bartkoske and W. Benbow and J. H. Buckley and Y. Chen and A. J. Chromey and A. Duerr and M. Errando and M. Escobar Godoy and A. Falcone and S. Feldman and Q. Feng and S. Filbert and L. Fortson and A. Furniss and W. Hanlon and O. Hervet and C. E. Hinrichs and J. Holder and T. B. Humensky and W. Jin and M. N. Johnson and P. Kaaret and M. Kertzman and M. Kherlakian and D. Kieda and T. K. Kleiner and N. Korzoun and S. Kumar and M. J. Lang and M. Lundy and G. Maier and P. Moriarty and R. Mukherjee and M. Ohishi and R. A. Ong and A. Pandey and M. Pohl and E. Pueschel and J. Quinn and P. L. Rabinowitz and K. Ragan and D. Ribeiro and E. Roache and I. Sadeh and L. Saha and G. H. Sembroski and R. Shang and J. V. Tucci and V. V. Vassiliev and A. Weinstein and D. A. Williams and S. L. Wong and T. Yoshikoshi and (VERITAS Collaboration)}, doi = {10.3847/1538-4357/adf6b6}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {28}, shortjournal = {The Astrophys. J.}, title = {Multiwavelength study of HESS j0632+057: New insights into Pulsar–Disk interaction}, volume = {991}, year = {2025}, }
• (2025). The X-ray variability and luminosity function of high-mass X-ray binaries in the dwarf starburst galaxy IC 10. ApJ, 991(1), 27. (www)

  @article{ , abstract = {We present an analysis of ∼235 ks of Chandra observations obtained over ∼19 yr of the nearby dwarf starburst galaxy IC 10 in order to study the X-ray variability and X-ray luminosity function (XLF) of its X-ray binary (XRB) population. We identify 23 likely XRBs within the Two Micron All Sky Survey K S isophotal radius and find the distributions of their dynamic ranges and duty cycles are consistent with a young, high-mass XRB (HMXB) population dominated by supergiant-fed systems, consistent with previous work. In general, we find that brighter HMXBs (those with L X ≳ several ×10 36 erg s −1 ) have higher duty cycles (i.e., are more persistent X-ray sources) than fainter objects, and the dynamic ranges of the sgHMXBs in the lower-metallicity environment of IC 10 are higher than what is observed for comparable systems in the Milky Way. After filtering out foreground stars on the basis of Gaia parallaxes, we construct, for the first time, the XLF of IC 10. We then use the XLF to model the star formation history of the galaxy, finding that a very recent (3–8 Myr) burst of star formation with a rate of ∼0.5 M ⊙ yr −1 is needed to adequately explain the observed bright end ( L X ∼ 10 37 erg s −1 ) of the HMXB XLF.}, archive = {J_ApJ}, author = {Breanna A. Binder and Rosalie Lazarus and Mina Thoresen and Silas Laycock and Sayantan Bhattacharya}, doi = {10.3847/1538-4357/adf7a7}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {27}, shortjournal = {The Astrophys. J.}, title = {The X-ray variability and luminosity function of high-mass X-ray binaries in the dwarf starburst galaxy IC 10}, volume = {991}, year = {2025}, }
• (2025). Parallel collisionless shocks in strongly magnetized Electron–Ion plasma. i. temperature anisotropies. ApJ, 991(1), 26. (www)

  @article{ , abstract = {Collisionless electron–ion shocks are fundamental to astrophysical plasmas, yet their behavior in strong magnetic fields remains poorly understood. Using particle-in-cell simulations with the SHARP-1D3V code, we investigate the role of the ion magnetization parameter σ i in parallel shock transitions. Strongly magnetized converging flows ( σ i > 1) exhibit lower-density compression ratios ( R ∼ 2), smaller entropy jumps, and suppressed particle acceleration while maintaining pressure anisotropy stability due to conserved perpendicular temperatures across the transition region, alongside increased parallel temperatures. In contrast, weakly magnetized shocks drive downstream mirror and firehose instabilities due to ion temperature anisotropy, which are suppressed in strongly magnetized cases. Additionally, weakly magnetized shocks exhibit the onset of a suprathermal population induced by shock-drift acceleration, with most of the upstream kinetic energy thermalized for both electrons and ions in the downstream region. Our results demonstrate that perpendicular temperatures for both species are conserved in weakly and strongly magnetized cases and highlight deviations from standard ideal magnetohydrodynamic behavior in strongly magnetized cases. These findings provide critical insights into the role of magnetic fields in parallel collisionless astrophysical shocks.}, archive = {J_ApJ}, author = {Mohamad Shalaby and Antoine Bret and Federico Fraschetti}, doi = {10.3847/1538-4357/adf84f}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {26}, shortjournal = {The Astrophys. J.}, title = {Parallel collisionless shocks in strongly magnetized Electron–Ion plasma. i. temperature anisotropies}, volume = {991}, year = {2025}, }
• (2025). Serendipitous discovery of a young cluster of galaxies at z ∼ 0.5 projected next to the nearby tadpole galaxy KUG 1138 + 327. ApJ, 991(1), 25. (www)

  @article{ , abstract = {Using a 90 ks Chandra ACIS-S observation in the 0.3–7 keV band, along with complementary Low-Frequency Array and Karl G. Jansky Very Large Array data in the 120–168 MHz and 1–2 GHz ranges, we study the diffuse emission around the nearby dwarf galaxy KUG 1138+327. Our analysis reveals a diffuse X-ray feature on the southern side, disconnected from the galactic disk. This feature exhibits a hard X-ray spectrum, which is highly unusual for an outflow from a dwarf galaxy. We interpret the irregularly shaped feature as hot plasma in a young galaxy cluster at redshift 0.5, supported by X-ray spectral fitting and consistent with the optical redshift of the central elliptical galaxy of a known cluster identified by a red sequence. Additionally, we detect a radio lobe east of the X-ray feature, likely produced by an active galactic nucleus (AGN) offset from the cluster center and confined primarily by ram pressure from the ambient medium. The lobe shows a steep nonthermal radio spectrum, suggesting a cosmic-ray age of ≳5 × 10 7 yr. Assuming energy equipartition between cosmic rays and magnetic fields, we estimate the lobe’s total energy to be ∼9 × 10 56 erg, comparable to the thermal energy in the same volume. This study thus identifies a background young cluster projected next to KUG 1138+327 and highlights the potentially significant role of off-center AGN feedback in shaping the intracluster medium.}, archive = {J_ApJ}, author = {Q. Daniel Wang and Juergen Ott}, doi = {10.3847/1538-4357/adfc74}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {25}, shortjournal = {The Astrophys. J.}, title = {Serendipitous discovery of a young cluster of galaxies at z ∼ 0.5 projected next to the nearby tadpole galaxy KUG 1138 + 327}, volume = {991}, year = {2025}, }
• (2025). Discovery of SiC and iron dust around AGB stars in the very metal-poor sextans a dwarf galaxy with JWST: Implications for dust production at high redshift. ApJ, 991(1), 24. (www)

  @article{ , abstract = {Low-resolution infrared spectroscopy from JWST confirms the presence of SiC and likely metallic iron dust around asymptotic giant branch (AGB) stars in the Sextans A dwarf galaxy, which has a metallicity ∼1%–7% Z ⊙ . While metal-poor carbon-rich AGB stars are known to produce copious amounts of amorphous carbon dust owing to the dredge up of newly synthesized carbon, this is the first time that Si- and Fe-bearing dust has been detected at this extreme metallicity. Of the six AGB stars observed, one is an intermediate-mass (∼1.2–4 M ⊙ ) carbon star showing SiC dust, and another is an oxygen-rich M-type star with mass ∼4–5 M ⊙ that is likely undergoing hot bottom burning. The infrared excess of the M-type star is strong, but featureless. We tested multiple dust species, and found that it is best fit with metallic iron dust. Assuming its dust-production rate stays constant over the final 2–3 × 10 4 yr of its evolution, this star will produce ∼0.9–3.7 times the iron dust mass predicted by models, with the range depending on the adopted stellar mass. The implications for dust production in high-redshift galaxies are potentially significant, especially regarding the assumed dust species used in dust evolution models and the timescale of AGB dust formation. Stars on the upper end of the AGB mass range can begin producing dust as early as 30–50 Myr after they form, and they may therefore rival dust production by supernovae at high redshift.}, archive = {J_ApJ}, author = {M. L. Boyer and G. C. Sloan and A. Nanni and E. Tarantino and I. McDonald and S. Goldman and J. A. D. L. Blommaert and F. Dell’Agli and M. Di Criscienzo and D. A. García-Hernández and Robert D. Gehrz and M. A. T. Groenewegen and A. Javadi and O. C. Jones and F. Kemper and M. Marengo and Kristen B. W. McQuinn and Joana M. Oliveira and Giada Pastorelli and Julia Roman-Duval and R. Sahai and Evan D. Skillman and S. Srinivasan and J. Th. van Loon and Daniel R. Weisz and Patricia A. Whitelock}, doi = {10.3847/1538-4357/adf06a}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {24}, shortjournal = {The Astrophys. J.}, title = {Discovery of SiC and iron dust around AGB stars in the very metal-poor sextans a dwarf galaxy with JWST: Implications for dust production at high redshift}, volume = {991}, year = {2025}, }
• (2025). Full-sky models of galactic microwave emission and polarization at subarcminute scales for the python sky model. ApJ, 991(1), 23. (www)

  @article{ , abstract = {Polarized foreground emission from the Galaxy is one of the biggest challenges facing current and upcoming cosmic microwave background (CMB) polarization experiments. We develop new models of polarized Galactic dust and synchrotron emission at CMB frequencies that draw on the latest observational constraints; that employ the “polarization fraction tensor” framework to couple intensity and polarization in a physically motivated way; and that allow for stochastic realizations of small-scale structure at subarcminute angular scales currently unconstrained by full-sky data. We implement these models into the publicly available Python Sky Model ( PySM ) software and additionally provide PySM interfaces to select models of dust and CO emission from the literature. We characterize the behavior of each model by quantitatively comparing it to observational constraints in both maps and power spectra, demonstrating an overall improvement over previous PySM models. Finally, we synthesize models of the various Galactic foreground components into a coherent suite of three plausible microwave skies that span a range of astrophysical complexity allowed by current data. Author contributions to this paper can be found at the end of this work.}, archive = {J_ApJ}, author = {The Pan-Experiment Galactic Science Group and Julian Borrill and Susan E. Clark and Jacques Delabrouille and Andrei V. Frolov and Shamik Ghosh and Brandon S. Hensley and Monica D. Hicks and Nicoletta Krachmalnicoff and King Lau and Myra M. Norton and Clement Pryke and Giuseppe Puglisi and Mathieu Remazeilles and Elisa Russier and Benjamin Thorne and Jian Yao and Andrea Zonca}, doi = {10.3847/1538-4357/adf212}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {23}, shortjournal = {The Astrophys. J.}, title = {Full-sky models of galactic microwave emission and polarization at subarcminute scales for the python sky model}, volume = {991}, year = {2025}, }
• (2025). Radiation-hydrodynamics effects in an inhomogeneous medium. ApJ, 991(1), 22. (www)

  @article{ , abstract = {Radiation flow through an inhomogeneous medium is critical in a wide range of physics and astronomy applications, from transport across cloud layers on the Earth to the propagation of supernova blast waves producing ultraviolet and X-ray emission. Radiation interacts with matter, driving hydrodynamic feedback that further alters the radiation characteristics (energy and angular distribution). This paper reviews the current state of the art in the modeling of inhomogeneous radiation transport, subgrid models developed to capture this often-unresolved physics, and the experiments designed to improve our understanding of these models. This paper focuses on simulations based on upcoming experiments designed to test this physics. We present a series of detailed simulations (both single-clump and multi-clump conditions) probing the dependence on the physical properties of the radiation front (e.g., radiation energy) and material characteristics (specific heat, opacity, clump densities). We find that, unless the radiation pressure is high, the clumps will heat and then expand, effectively cutting off the radiation flow. The expanding winds can also produce shocks that generates high-energy emission. We compare our detailed simulations with some of the current subgrid prescriptions, identifying some of the limitations of these current models.}, archive = {J_ApJ}, author = {Christopher L. Fryer and Paul A. Keiter and Vidushi Sharma and Joshua Leveillee and D. D. Meyerhofer and D. H. Barnak and Tom Byvank and A. T. Elshafiey and Christopher J. Fontes and Heather M. Johns and P. M. Kozlowski and Todd Urbatsch}, doi = {10.3847/1538-4357/adf6b4}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {22}, shortjournal = {The Astrophys. J.}, title = {Radiation-hydrodynamics effects in an inhomogeneous medium}, volume = {991}, year = {2025}, }
• (2025). The role of rotation on the yields of the two γ-ray emitters 26Al and 60Fe ejected by massive stars. ApJ, 991(1), 21. (www)

  @article{ , abstract = {We show that the observed 60 Fe/ 26 Al flux ratio provided by the SPectrometer on INTEGRAL satellite (0.24 ± 0.04) can be reproduced only if rotation is taken into account in the computation of the stellar models. Predictions from nonrotating stellar models yield a significantly lower ratio (0.062), which is incompatible with the observed value. The adopted models and the associated yields are based on a combination of models already published by M. Limongi & A. Chieffi, complemented by additional ones fully consistent with the original grid, allowing a finer resolution in the initial rotational velocity distribution.}, archive = {J_ApJ}, author = {Agnese Falla and Lorenzo Roberti and Marco Limongi and Alessandro Chieffi}, doi = {10.3847/1538-4357/adfa05}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {21}, shortjournal = {The Astrophys. J.}, title = {The role of rotation on the yields of the two γ-ray emitters 26Al and 60Fe ejected by massive stars}, volume = {991}, year = {2025}, }
• (2025). AT2022sxl: A candidate repeating tidal disruption event in possible association with two high-energy neutrino events. ApJ, 991(1), 20. (www)

  @article{ , abstract = {We report a candidate repeating tidal disruption event (TDE), AT2022sxl, found from large-field optical survey data. Two flares with a separation time of ∼7.2 yr between the two optical peaks are observed. Related mid-infrared (MIR) flares, with delay times of ∼200 days are also seen. We analyze two optical spectra of the TDE source, one near the optical peak of the second flare from the Transient Name Server and one at the quiescent flux level after the second flare. The latter was taken by us with the 10.4 m Gran Telescopio Canarias. Comparing the features of the two spectra, we identify that the host is likely a composite galaxy at redshift 0.23, and the TDE event, probably an H+He type, mainly powered broad components in the emission lines of H α , H β , and He I λ 5876. More interestingly, we find that two Bronze-type neutrino events, detected by the IceCube neutrino observatory, match the TDE in position and the second flare, especially the delayed MIR flare, in time. We discuss the MIR luminosity properties of the currently reported (candidate) neutrino-emitting TDEs and suggest that luminous MIR emission is a prerequisite for neutrino production in TDEs.}, archive = {J_ApJ}, author = {Shunhao Ji and Zhongxiang Wang and Litao Zhu and Stefan Geier and Alok C. Gupta}, doi = {10.3847/1538-4357/adfb73}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {20}, shortjournal = {The Astrophys. J.}, title = {AT2022sxl: A candidate repeating tidal disruption event in possible association with two high-energy neutrino events}, volume = {991}, year = {2025}, }
• (2025). Geminga: A window into the role played by the local halo in the cosmic-ray propagation process. ApJ, 991(1), 19. (www)

  @article{ , abstract = {A novel phenomenon among the recently observed Geminga pulsar halo is the presence of distinct radiation morphology at high energies, while no extended radiation is detected in the 10–500 GeV energy band within a 40° × 40° region. This phenomenon suggests that pulsar halos play a crucial role in the local propagation of cosmic rays, making it necessary to investigate the underlying mechanisms of this phenomenon. This work focuses on the 3D propagation study of cosmic rays, incorporating the Geminga pulsar into our propagation framework to investigate its contribution to different observational spectra. We consider Geminga a dominant local source of positrons, partially reproducing the observed positron spectrum and multiwavelength radiative spectra of the Geminga halo. Through calculations of signal and background at different angles, we find that: (1) the slow-diffusion properties near the Geminga pulsar and its proper motion may cause the radiation from electrons originating from Geminga to be distributed across a more extended region, and (2) the incomplete subtraction of radiation from the local halo may contribute, to some extent, to the diffuse gamma-ray fluctuations detected by LHAASO. We hope that LHAASO will detect more sources of cosmic-ray halo to further validate our model.}, archive = {J_ApJ}, author = {Lin Nie and Yu-Hai Ge and Yi-Qing Guo and Si-Ming Liu}, doi = {10.3847/1538-4357/adfcd8}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {19}, shortjournal = {The Astrophys. J.}, title = {Geminga: A window into the role played by the local halo in the cosmic-ray propagation process}, volume = {991}, year = {2025}, }
• (2025). Alfvén wave heating of solar chromosphere reexamined. ApJ, 991(1), 18. (www)

  @article{ , abstract = {Models of heating the weakly ionized solar atmosphere by collisional damping of upward-propagating Alfvén waves, calculated under the assumption that only incompressible (intermediate-mode) MHD waves are involved, have predicted heating rates that do not agree with the empirically inferred radiative energy loss from the chromosphere. The assumption that incompressible intermediate-mode waves can propagate through the inhomogeneous three-dimensional solar atmosphere without coupling to compressible fast- or slow-mode waves is shown to restrict the configuration of the ambient magnetic field, requiring symmetry conditions that are not satisfied in the solar atmosphere. In a magnetic field without those symmetries, propagating Alfvén waves necessarily generate waves in other MHD modes, which must be included in any realistic model of wave heating.}, archive = {J_ApJ}, author = {Vytenis M. Vasyliūnas}, doi = {10.3847/1538-4357/adeaae}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {18}, shortjournal = {The Astrophys. J.}, title = {Alfvén wave heating of solar chromosphere reexamined}, volume = {991}, year = {2025}, }
• (2025). Searching for binary black hole subpopulations in gravitational-wave data using binned gaussian processes. ApJ, 991(1), 17. (www)

  @article{ , abstract = {Astrophysically motivated population models for binary black hole (BBH) observables are often insufficient to capture the imprints of multiple formation channels. This is mainly due to the strongly parametrized nature of such investigations. Using a nonparametric model for the joint population-level distributions of BBH component masses and effective inspiral spins, we find hints of multiple subpopulations in the third gravitational-wave transient catalog. The higher (more positive) spin subpopulation is found to have a mass spectrum without any feature at in the 30–40 M ⊙ range, which is consistent with the predictions of isolated stellar binary evolution, simulations for which place the pileup due to pulsational pair-instability supernovae near 50 M ⊙ or higher. The other subpopulation with effective spins closer to zero shows a feature at 30–40 M ⊙ and is consistent with BBHs formed dynamically in globular clusters, which are expected to peak around 30 M ⊙ . We also compute merger rates for these two subpopulations and find that they are consistent with the theoretical predictions of the corresponding formation channels. We validate our results by checking their robustness against variations of several model configurations and by analyzing large simulated catalogs with the same model.}, archive = {J_ApJ}, author = {Anarya Ray and Ignacio Magaña Hernandez and Katelyn Breivik and Jolien Creighton}, doi = {10.3847/1538-4357/adf22a}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {17}, shortjournal = {The Astrophys. J.}, title = {Searching for binary black hole subpopulations in gravitational-wave data using binned gaussian processes}, volume = {991}, year = {2025}, }
• (2025). Pumping iron: How turbulent metal diffusion impacts multiphase galactic outflows. ApJ, 991(1), 16. (www)

  @article{ , abstract = {Most numerical simulations of galaxy formation and evolution are unable to properly resolve the turbulent cascade at or below the resolution scale and turbulence models are required to capture the motion of eddies on those unresolved scales. We investigate the impact of turbulent metal diffusion on multiphase outflows originating from dwarf galaxies ( M halo ∼ 10 10 −10 11 M ⊙ ). We use our state-of-the-art numerical model for the formation of single stars and nonequilibrium cooling and chemistry. We run the simulations at a resolution of ∼4 M ⊙ , and resolve individual supernova explosions in terms of hot phase and momentum input. We find that the mass, energy, and metal loading factors are only weakly affected by the inclusion of a metal diffusion model. The metal enrichment factor at low altitudes above the galactic disk is higher by around 20% when the metal diffusion model is included. Specifically, we find more efficient cooling in the cold interstellar medium, due to more efficient metal mixing that leads to shorter cooling times of the warm gas, which becomes available more quickly for star formation. The most striking effect of the metal diffusion model is that, without metal diffusion, there is more rapid cooling in the hot phase and a reduced sound speed by a factor of 2. Specifically, we find that the hot phase is more metal enriched in the case without metal diffusion leading to more rapid overcooling of that phase, which is consistent with the higher sound speed we find in the runs with metal diffusion.}, archive = {J_ApJ}, author = {Ulrich P. Steinwandel and Douglas Rennehan and Matthew E. Orr and Drummond B. Fielding and Chang-Goo Kim}, doi = {10.3847/1538-4357/adf283}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {16}, shortjournal = {The Astrophys. J.}, title = {Pumping iron: How turbulent metal diffusion impacts multiphase galactic outflows}, volume = {991}, year = {2025}, }
• (2025). On the origin and dynamical evolution of jupiter’s moon amalthea. ApJ, 991(1), 15. (www)

  @article{ , abstract = {Interior to the orbits of Jupiter’s iconic Galilean moons are four small satellites with individual mean radii R ≲ 84 km. Multiple lines of evidence suggest that these bodies formed at a more distant location in Jupiter’s circumplanetary disk before coming to reside at their current short-period orbits. However, how these moons dynamically evolved to such a location has yet to be explained in the emerging paradigm of Jovian satellite formation. Here, we present a quantitative model for the origin of the largest of these inner moons, Amalthea, that can be extended to its neighbor, Thebe, and to other small bodies in astrophysical disks. We propose that Amalthea’s anomalous features are due to it having formed alongside the Galileans in a reservoir of satellitesimals located at a large Jovian-centric distance. As the innermost Galilean, Io, migrated inward from this reservoir, it captured the satellitesimal Amalthea into resonance and shepherded the small body to its modern neighborhood. During this migration through the disk, dissipative forcing from aerodynamic drag induces overstable librations in the Io–Amalthea resonance, such that only a narrow range of nebular parameters can accommodate the requisite long-range transport. In particular, the disk aspect ratio, h / r , emerges as the key variable. Our calculations indicate that the circumjovian disk had a scale height of h / r ≳ 0.08, implying a relatively hot, actively accreting disk during the epoch of satellite formation. These results thus shed light on the evolution of the Jovian system, along with the more general phenomenon of satellite–disk interactions.}, archive = {J_ApJ}, author = {Ian R. Brunton and Konstantin Batygin}, doi = {10.3847/1538-4357/adf432}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {15}, shortjournal = {The Astrophys. J.}, title = {On the origin and dynamical evolution of jupiter’s moon amalthea}, volume = {991}, year = {2025}, }
• (2025). SDSS-IV MaNGA: Physical origins of double-peaked narrow emission-line spaxels in barred galaxies. ApJ, 991(1), 14. (www)

  @article{ , abstract = {The physical origins of double-peaked narrow emission-line spaxels (DPSs) in barred galaxies are explored through the analysis of a sample of 72 barred double-peaked emission-line galaxies (DPGs) extracted from the MaNGA data set. In this study, we examine two potential scenarios: the gas inflow along the bar and the formation of a bar-induced gaseous nuclear ring. By applying a classical galactic dynamics model, we calculate the radii and rotational velocities of the nuclear rings for all barred DPGs and compare them with the observed properties of their DPSs. Our analysis reveals a significant correlation between the predicted radii of the nuclear rings and the maximum centric distances of the DPSs, as well as a marginal correlation between the predicted rotational velocities of the nuclear rings and the observed maximum velocity differences of the DPSs. These findings provide strong evidence to support the hypothesis that the DPSs of a barred DPG in MaNGA primarily originate from the convolution of the point-spread function effect with its bar-induced fast-rotating gaseous nuclear ring.}, archive = {J_ApJ}, author = {Jiajie Qiu and Shiyin Shen and Ruixiang Chang and Qianwen Zhao and Qi Zeng}, doi = {10.3847/1538-4357/adf4d1}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {14}, shortjournal = {The Astrophys. J.}, title = {SDSS-IV MaNGA: Physical origins of double-peaked narrow emission-line spaxels in barred galaxies}, volume = {991}, year = {2025}, }
• (2025). Jet collimation profile of the low-luminosity active galactic nucleus m84: Insight into the jet formation in the low-accretion regime. ApJ, 991(1), 13. (www)

  @article{ , abstract = {Recent advancements in high-resolution very long baseline interferometry have significantly improved our understanding of jet collimation near supermassive black holes in active galactic nuclei (AGNs), particularly in high-power systems. However, the collimation properties of jets in low-luminosity AGNs (LLAGNs) remain poorly explored. In this study, we investigate the jet structure of M84, a nearby radio galaxy and a representative LLAGN, to probe jet collimation properties in the low-accretion regime. Utilizing astrometric phase-referencing observations from the Very Long Baseline Array, supplemented by archival Very Large Array data, we trace the jet geometry of M84 over a broad range of scales, from ∼10 2 to ∼10 7 Schwarzschild radii ( r s ). Our analysis reveals a well-defined transition from a semiparabolic profile, W ( r ) ∝ r 0.71 , to a conical shape, W ( r ) ∝ r 1.16 , occurring at approximately 1.67 × 10 4 r s . This indicates that the M84 jet is notably less collimated than those in other known LLAGN sources. Our findings provide new insights into the relationship between jet collimation and accretion rate, offering crucial constraints for jet formation models of LLAGNs.}, archive = {J_ApJ}, author = {Elika P. Fariyanto and Kazuhiro Hada and Yuzhu Cui and Mareki Honma and Masanori Nakamura and Keiichi Asada and Xuezheng Wang and Wu Jiang}, doi = {10.3847/1538-4357/adf4d9}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {13}, shortjournal = {The Astrophys. J.}, title = {Jet collimation profile of the low-luminosity active galactic nucleus m84: Insight into the jet formation in the low-accretion regime}, volume = {991}, year = {2025}, }
• (2025). Rotational dynamics in pulsational pair-instability supernovae: Implications for mass loss and transient events. ApJ, 991(1), 12. (www)

  @article{ , abstract = {Pulsational pair-instability supernovae (PPISNe) are transient events occurring in progenitor stars with He cores of ∼32–65 M ⊙ , where rapid electron–positron pair production induces pressure loss, collapse, and pulsations driving episodic mass loss. The number, strength, and duration of these pulses can lead to shell collisions that produce shock-powered transients, potentially explaining some of the most luminous events, such as superluminous supernovae, and other rare transients. Rapid progenitor rotation lowers the PPISN mass threshold and influences the dynamics, energetics, and chemical composition of PPISN-driven pulses. In this study, we computed 1D evolutionary models of massive, rotating PPISN progenitor stars with ZAMS masses of 85–140 M ⊙ and metallicities of Z ⊙ and 0.1 Z ⊙ . Our analysis reveals strong correlations between PPISN ejected mass and total energy, as well as between ejected mass and peak ejected shell velocity. Additionally, moderate correlations indicate that higher initial PPISN progenitor mass leads to greater mass ejection and energy release, while negative correlations show that rapid rotation appears to reduce mass ejection and kinetic energy of the shells. Subsequent pulses lead to H-poor, C- and O-enriched ejected shells, indicating the effect of rotationally induced chemical mixing, PPISN-driven episodic mass loss with implications for their transients. We model the light curve and synthetic spectra that arise from the collision of two H-poor shells for one of our models using the radiation transport code SuperLite . We find that shock-heated H-poor PPISN shell collisions from rapidly rotating progenitors can lead to moderately luminous H-poor transients that share some similarities with observed superluminous supernova I events.}, archive = {J_ApJ}, author = {Trang N. Huynh and Emmanouil Chatzopoulos and Nageeb Zaman}, doi = {10.3847/1538-4357/adf4e7}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {12}, shortjournal = {The Astrophys. J.}, title = {Rotational dynamics in pulsational pair-instability supernovae: Implications for mass loss and transient events}, volume = {991}, year = {2025}, }
• (2025). Primordial black hole triggered type ia supernovae. i. impact on explosion dynamics and light curves. ApJ, 991(1), 11. (www)

  @article{ , abstract = {Primordial black holes (PBHs) in the asteroid-mass window are compelling dark matter candidates, made plausible by the existence of black holes and by the variety of mechanisms of their production in the early Universe. If a PBH falls into a white dwarf (WD), the strong tidal forces can generate enough heat to trigger a thermonuclear runaway explosion, depending on the WD’s mass and the PBH’s orbital parameters. In this work, we investigate the WD explosion triggered by the passage of a PBH. We perform 2D simulations of the WD undergoing thermonuclear explosion in this scenario, with the predicted ignition site as a parameter assuming the deflagration–detonation transition model. We study the explosion dynamics, and predict the associated light curves and nucleosynthesis. We find that the model sequence predicts light curves which align with the Phillips relation ( {B}_{\max } versus Δ M 15 ). Our models hint at a unifying approach in triggering Type Ia supernovae without involving two distinctive evolutionary tracks.}, archive = {J_ApJ}, author = {Shing-Chi Leung and Seth Walther and Ken’ichi Nomoto and Alexander Kusenko}, doi = {10.3847/1538-4357/adf4e8}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {11}, shortjournal = {The Astrophys. J.}, title = {Primordial black hole triggered type ia supernovae. i. impact on explosion dynamics and light curves}, volume = {991}, year = {2025}, }
• (2025). Capturing star formation activity from compressed photometric images of galaxies. ApJ, 991(1), 10. (www)

  @article{ , abstract = {We present a novel approach for classifying star-forming galaxies using photometric images. By utilizing approximately 124,000 optical color composite images and spectroscopic data of nearby galaxies at 0.01 < z < 0.06 from the Sloan Digital Sky Survey, along with follow-up spectroscopic line measurements from the OSSY catalog, and leveraging the vision transformer machine learning technique, we demonstrate that galaxy images in JPEG format alone can be directly used to determine whether star-forming activity dominates the galaxy, bypassing traditional spectroscopic analyses such as emission-line diagnostic diagrams. We anticipate that this method holds significant potential for application in current and future large-scale surveys, such as Euclid, the Dark Energy Survey, and the Legacy Survey of Space and Time.}, archive = {J_ApJ}, author = {Kyuseok Oh and M. Dennis Turp}, doi = {10.3847/1538-4357/adf63d}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {10}, shortjournal = {The Astrophys. J.}, title = {Capturing star formation activity from compressed photometric images of galaxies}, volume = {991}, year = {2025}, }
• (2025). The superMIGHTEE project: MeerKAT and GMRT together to unveil the deep radio sky. ApJ, 991(1), 9. (www)

  @article{ , abstract = {An international team of researchers has come together to undertake an ultra-broadband exploration of the deep radio sky. The superMIGHTEE project combines data from the MIGHTEE project, using the precursor Square Kilometre Array MeerKAT telescope in South Africa, with observations from the upgraded Giant Metrewave Radio Telescope (uGMRT) in India to produce deep images at several μ Jy sensitivity over a frequency range of 200 MHz–2.5 GHz, with an angular resolution of a few arcseconds. This paper describes the initial superMIGHTEE uGMRT data release, comprising total intensity continuum images covering a total of 9.9 deg 2 at 650 MHz and 6.9 deg 2 at 400 MHz in the XMM-LSS, COSMOS, and E-CDFS deep fields. The associated radio source catalogues include 27,101 sources at 650 MHz and 10,946 sources at 400 MHz. The redshift distribution of the sources extends to z ∼ 4 with a median value of z = 1. An overview of the broadband spectra of the sources, in combination with the MeerKAT MIGHTEE 1280 MHz data, reveals a clear change in spectral properties at the transition from an active galactic nuclei-dominated population to a population dominated by star-forming galaxies at flux densities of a few mJy. At higher frequencies, the star-forming galaxy population exhibits an optically thin synchrotron spectral index indicative of energy injection from supernovae. At lower frequencies, the spectra flatten significantly with decreasing flux density, and the fraction of sources with peaked spectra increases. This is the first superMIGHTEE uGMRT data release. Subsequent releases will include spectro-polarimetric and spectral line image cubes, as well as images at lower frequencies. The goal of the superMIGHTEE ultra-wideband data set is to enhance our understanding of the evolution of active galactic nuclei and star-forming galaxies over cosmic time, shed light on the evolution of neutral hydrogen, and explore the origins and evolution of cosmic magnetic fields in clusters, filaments, and galaxies.}, archive = {J_ApJ}, author = {Dharam V. Lal and Russ Taylor and Srikrishna Sekhar and Ch. Ishwara-Chandra and Sushant Dutta and Sthabile Kolwa}, doi = {10.3847/1538-4357/adf6dc}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {9}, shortjournal = {The Astrophys. J.}, title = {The superMIGHTEE project: MeerKAT and GMRT together to unveil the deep radio sky}, volume = {991}, year = {2025}, }
• (2025). The energy cascade rate in supersonic magnetohydrodynamic turbulence. ApJ, 991(1), 8. (www)

  @article{ , abstract = {Three-dimensional direct numerical simulations are implemented to investigate the energy cascade rate in compressible isothermal magnetohydrodynamic turbulence. Utilizing an exact law derived from the Kármán–Howarth equation, we examine the contributions of flux and nonflux terms to the cascade rate across a broad range of sonic and Alfvénic Mach numbers, from subsonic to supersonic regimes and with varying mean magnetic fields. The cascade rates are computed using on-grid 3D decomposition and two plasma increment approaches: signed and absolute values. The anisotropy induced by strong magnetic fields is analyzed through angular-dependent scaling of the cascade terms. Moreover, the increment calculation method significantly influences the relative contributions of the flux and nonflux terms, with absolute methods tending to overestimate the latter. These findings extend current studies of compressible turbulence and offer critical insights into energy transfer mechanisms relevant to many astrophysical phenomena.}, archive = {J_ApJ}, author = {Gonzalo Javier Alvarez and Pablo Dmitruk and Branislav Rabatin and David C. Collins and Nahuel Andrés}, doi = {10.3847/1538-4357/adf6df}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {8}, shortjournal = {The Astrophys. J.}, title = {The energy cascade rate in supersonic magnetohydrodynamic turbulence}, volume = {991}, year = {2025}, }
• (2025). PEARLS: Globular clusters and ultracompact dwarfs in the el gordo galaxies at z = 0.87. ApJ, 991(1), 7. (www)

  @article{ , abstract = {JWST/NIRCam 0.9 to 2.0 μ m images reveal a population of point sources around the major galaxies in the El Gordo cluster at redshift z = 0.87. Their distribution in the color–magnitude diagrams shows a narrow sequence well separated from field-galaxy contamination and consistent with their identification as ultracompact dwarf galaxies (UCDs) or luminous globular clusters (GCs). The point-source sequence is more luminous by almost a magnitude than the corresponding sequence in Abell 2744 at z = 0.31, matching the predicted evolutionary change for GC/UCDs over the 4 Gyr difference in look-back time between these two clusters. Deeper observations should allow direct JWST imaging of GC/UCD populations, even without the help of lensing, up to z ∼ 1.4, a look-back time of more than 9 Gyr. Such observations would directly reveal the evolution of these compact stellar systems two-thirds of the way back to the Big Bang.}, archive = {J_ApJ}, author = {William E. Harris and Marta Reina-Campos and Anton M. Koekemoer and Jessica M. Berkheimer and Timothy Carleton and Seth H. Cohen and Brenda L. Frye and Tyler R. Hinrichs and Benne W. Holwerda and Rachel Honor and Massimo Ricotti and S. P. Willner and Rogier A. Windhorst and Haojing Yan}, doi = {10.3847/1538-4357/adf8dc}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {7}, shortjournal = {The Astrophys. J.}, title = {PEARLS: Globular clusters and ultracompact dwarfs in the el gordo galaxies at z = 0.87}, volume = {991}, year = {2025}, }
• (2025). Reprocessing of the parkes 70 cm survey and discovery of a new radio pulsar in the large magellanic cloud. ApJ, 991(1), 6. (www)

  @article{ , abstract = {We have reprocessed the data archived from the Parkes 70 cm (PKS70) pulsar survey with an expanded dispersion measure (DM) search range and an acceleration search. Our goal was to detect pulsars that might have been missed in the original survey processing. Of the original 43,842 pointings, 34,869 pointings were archived, along with 440 additional pointings for confirmation or timing. We processed all of these archived data and detected 359 known pulsars: 265 of these were detected in the original survey, while an additional 94 currently known pulsars were detected in our reprocessing. A few among those 94 pulsars are highly accelerated binary pulsars. Furthermore, we detected 5 more pulsars with DMs higher than the original survey thresholds, as well as 6 more pulsars below the nominal survey sensitivity threshold (from the original survey beams with longer integrations). We missed detection of 33 (of the 298) pulsars detected in the original survey, in part because of portions of the survey data missing in the archive and our early-stage candidate sifting method. We discovered one new pulsar in the reanalysis, PSR J0540−69, which has a spin period of 0.909 s and resides in the Large Magellanic Cloud (LMC). This new pulsar appeared in three PKS70 beams and one additional L -band observation that targeted the LMC pulsar PSR B0540−69. The numerous pulsar detections found in our reanalysis and the discovery of a new pulsar in the LMC highlight the value of conducting multiple searches through pulsar data sets.}, archive = {J_ApJ}, author = {Wenke Xia and Fronefield Crawford and Shinnosuke Hisano and Tai Jespersen and Melanie Ficarra and Mckenzie Golden and Mia Gironda}, doi = {10.3847/1538-4357/adf8e8}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {6}, shortjournal = {The Astrophys. J.}, title = {Reprocessing of the parkes 70 cm survey and discovery of a new radio pulsar in the large magellanic cloud}, volume = {991}, year = {2025}, }
• (2025). Ultraviolet and gravitational wave signatures of magnetar formation. ApJ, 991(1), 5. (www)

  @article{ , abstract = {We investigate the impact of gravitational wave (GW) emission by a newly born magnetar onto its electromagnetic (EM) counterparts in the Ultraviolet Transient Astronomy Satellite (ULTRASAT) band. In particular, we carry out a numerical calculation of magnetar-powered shock breakouts (SBOs) and supernova (SN) light curves. We find that an early SBO peak in the bolometric light curves provides a likely signature of a magnetar central engine, which can help constrain the magnetar’s spin period and magnetic dipole. Moreover, our results show that GW emission by the magnetar has only a minor effect on the SBO light curve. Such SBOs can be detected by ULTRASAT at a rate ∼1–2 yr −1 , provided that the magnetar wind is not efficiently thermalized during the early phases of the evolution. We additionally find that the subsequent SN light curves can be more luminous than SBOs in the ULTRASAT band and can thus be detected at a higher rate. Finally, we find a possible late-time signature of GW emission in the SN light curves, which may provide an additional tool for the detection of GW signals. Our results demonstrate that future ULTRASAT observations will provide crucial insights into the magnetar formation process and unique information for direct searches of long-transient signals with current and future generation GW detectors. In particular, we estimate a rate of multimessenger (UV+GW) detections of newly formed magnetars ≳1 every 2 yr with ULTRASAT and the Einstein Telescope.}, archive = {J_ApJ}, author = {Simone Dall’Osso and Dafne Guetta}, doi = {10.3847/1538-4357/adfa8c}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {5}, shortjournal = {The Astrophys. J.}, title = {Ultraviolet and gravitational wave signatures of magnetar formation}, volume = {991}, year = {2025}, }
• (2025). Contribution of globular clusters to diffuse gamma-ray emission from the galactic plane. ApJ, 991(1), 4. (www)

  @article{ , abstract = {The diffuse Galactic gamma-ray emission (DGE) provides a valuable probe for investigating the cosmic-ray propagation and interactions within our Galactic environment. Recent observations have demonstrated systematic excesses of DGE compared with the conventional cosmic-ray propagation model predictions. While gamma-ray emissions have been detected in a subset of globular clusters, their undetected populations may significantly contribute to the DGE. Motivated by this possibility, we present a comprehensive assessment of potential contributions from unresolved globular clusters to the DGE. In our analysis, a nonparametric method is employed to estimate the luminosity function and spatial distribution function of globular clusters using the Fermi-Large Area Telescope (LAT) fourth source catalog (4FGL) combined with a reference globular cluster catalog. Based on these distributions, we calculate the cumulative contribution of unresolved globular cluster populations to the DGE observed by Fermi-LAT and the Large High Altitude Air Shower Observatory. Our results reveal that globular clusters account for only ∼2% of the DGE at the TeV range, and smaller than 1% in the GeV regime, which is effectively negligible.}, archive = {J_ApJ}, author = {Jiayin He and Houdun Zeng and Yi Zhang and Xiaoyuan Huang and Qiang Yuan}, doi = {10.3847/1538-4357/adfd5b}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {4}, shortjournal = {The Astrophys. J.}, title = {Contribution of globular clusters to diffuse gamma-ray emission from the galactic plane}, volume = {991}, year = {2025}, }
• (2025). Observational biases on rotation curves from integral field unit data at cosmic noon. ApJ, 991(1), 3. (www)

  @article{ , abstract = {Through studying rotation curves, which depict how the velocity of the stars and gas changes with distance from the center of a galaxy, it has been confirmed that dark matter dominates galaxies’ outer regions, as their rotation curve remains flat. However, recent studies of star-forming galaxies at cosmic noon have shown a decline in their rotation curve beyond a certain point, suggesting a decrease of the abundance of dark matter in galactic halos during earlier times. In this work, we investigate the influence of cosmological surface brightness dimming and loss of resolution on observations of rotation curves at cosmic noon. We used a sample of 19 Lyman break analogs at z ∼ 0.2 and artificially redshifted them as if they were at z ∼ 2.2. By comparing both rotation curves of the observed and mocked objects, we find that the asymmetry of the cosmic noon galaxies is smaller than that of the low- z galaxies. In low- z galaxies, asymmetry increases with radius and becomes relevant at the external parts, where mergers and interactions cause more disturbance in the galaxy’s gravitational field. In contrast, cosmic-noon galaxies appear smoother, smaller, and suitable for dynamical modeling—when in reality they are not. The combined effects of the cosmological bias and loss of resolution lead us to the conclusion that caution should be exercised when using cosmic-noon rotation curves, as they might not accurately trace the gravitational potential of the galaxy.}, archive = {J_ApJ}, author = {Amanda E. Araujo-Carvalho and Thiago S. Gonçalves and Davor Krajnović and Karín Menéndez-Delmestre and Natanael de Isídio}, doi = {10.3847/1538-4357/adef06}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {3}, shortjournal = {The Astrophys. J.}, title = {Observational biases on rotation curves from integral field unit data at cosmic noon}, volume = {991}, year = {2025}, }
• (2025). Broadband spectral modeling of prompt emission from gamma-ray bursts observed by the transiting exoplanet survey satellite. ApJ, 991(1), 2. (www)

  @article{ , abstract = {Optical observations of gamma-ray bursts (GRBs) contemporaneous with their prompt high-energy emission are rare, but they can provide insights into the physical processes underlying these explosive events. The Transiting Exoplanet Survey Satellite’s (TESS's) large field of view and continuous observation capabilities make it uniquely positioned to detect and characterize prompt optical flashes from GRBs. In this work, we fit phenomenological models to the gamma-ray through optical spectral energy distributions (SEDs) of 24 bursts with arcsecond-level localizations that fell within the TESS field of view between 2018 July and 2024 December. In four cases, the extrapolation of the high-energy SED agrees with the observed optical flux to within 1 σ . In one case, there is a significant excess of optical flux relative to the extrapolation. In two cases, upper limits from TESS did not constrain the optical portion of the SED. In the remaining 17 cases, the optical flux is overpredicted by the extrapolation from high energies. This discrepancy could be explained by dust extinction in the host galaxy.}, archive = {J_ApJ}, author = {Rahul Jayaraman and Michael Fausnaugh and George R. Ricker and Roland Vanderspek}, doi = {10.3847/1538-4357/adea71}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {2}, shortjournal = {The Astrophys. J.}, title = {Broadband spectral modeling of prompt emission from gamma-ray bursts observed by the transiting exoplanet survey satellite}, volume = {991}, year = {2025}, }
• (2025). Meridional circulation molecular-weighted. ApJ, 991(1), 1. (www)

  @article{ , abstract = {Meridional circulation in stratified stellar/planetary interiors in the presence of stable molecular-weight gradients remains poorly understood, thereby affecting angular momentum transport in evolutionary models. We extend the downward control principle of atmospheric sciences to include compositional stratification. Using a linearized analysis, we show that stable μ -gradients slow down the penetration of circulation into the depths, emphasizing the importance of time-dependent solutions. However, additional effects such as horizontal turbulence or magnetic fields are needed to halt it completely. We also find limits demarcating linear and nonlinear regimes in terms of Schmidt and Rossby numbers. Nonlinear simulations exhibit compositional mixing due to meridional currents, enabling deeper penetration than otherwise. We propose slowly evolving and steady-state scenarios for the solar tachocline, and helioseismically observed heavy element abundances, while acknowledging the absence of constraints on the radial variation of the Schmidt number. In the context of stellar evolution, differential rotation profiles of solar-type main-sequence stars may follow analytical solutions extending from D. Banik & K. Menou, thereby aiding further probes into magneto/hydrodynamic instabilities and outward angular momentum transport.}, archive = {J_ApJ}, author = {Deepayan Banik and Kristen Menou and Evan H. Anders}, doi = {10.3847/1538-4357/adf851}, journal = {The Astrophysical Journal}, month = {9}, number = {1}, pages = {1}, shortjournal = {The Astrophys. J.}, title = {Meridional circulation molecular-weighted}, volume = {991}, year = {2025}, }
• (2025). Erratum: “Potential vorticity mixing in a tangled magnetic field” (2020, ApJ, 892, 24). ApJ, 990(2), 233. (www)

  @article{ , archive = {J_ApJ}, author = {Chang-Chun Chen and Patrick H. Diamond}, doi = {10.3847/1538-4357/adcc1f}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {233}, shortjournal = {The Astrophys. J.}, title = {Erratum: “Potential vorticity mixing in a tangled magnetic field” (2020, ApJ, 892, 24)}, volume = {990}, year = {2025}, }
• (2025). Erratum: “Superluminal proper motion in the X-ray jet of centaurus a” (2024, ApJ, 974, 307). ApJ, 990(2), 232. (www)

  @article{ , archive = {J_ApJ}, author = {David Bogensberger and Jon M. Miller and Richard Mushotzky and W. N. Brandt and Elias Kammoun and Abderahmen Zoghbi and Ehud Behar}, doi = {10.3847/1538-4357/adfbf2}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {232}, shortjournal = {The Astrophys. J.}, title = {Erratum: “Superluminal proper motion in the X-ray jet of centaurus a” (2024, ApJ, 974, 307)}, volume = {990}, year = {2025}, }
• (2025). Erratum: “Tripling the census of dwarf AGN candidates using DESI early data” (2025, ApJ, 982, 10). ApJ, 990(2), 231. (www)

  @article{ , archive = {J_ApJ}, author = {Ragadeepika Pucha and S. Juneau and Arjun Dey and M. Siudek and M. Mezcua and J. Moustakas and S. BenZvi and K. Hainline and R. Hviding and Yao-Yuan Mao and D. M. Alexander and R. Alfarsy and C. Circosta and Wei-Jian Guo and V. Manwadkar and P. Martini and B. A. Weaver and J. Aguilar and S. Ahlen and D. Bianchi and D. Brooks and R. Canning and T. Claybaugh and K. Dawson and A. de la Macorra and Biprateep Dey and P. Doel and A. Font-Ribera and J. E. Forero-Romero and E. Gaztañaga and S. Gontcho A Gontcho and G. Gutierrez and K. Honscheid and R. Kehoe and S. E. Koposov and A. Lambert and M. Landriau and L. Le Guillou and A. Meisner and R. Miquel and F. Prada and G. Rossi and E. Sanchez and D. Schlegel and M. Schubnell and H. Seo and D. Sprayberry and G. Tarlé and H. Zou}, doi = {10.3847/1538-4357/adfee0}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {231}, shortjournal = {The Astrophys. J.}, title = {Erratum: “Tripling the census of dwarf AGN candidates using DESI early data” (2025, ApJ, 982, 10)}, volume = {990}, year = {2025}, }
• (2025). Erratum: “Exploring the relationship between stellar mass, metallicity, and star formation rate at z ∼ 2.3 in KBSS-MOSFIRE” (2025, ApJ, 984, 188). ApJ, 990(2), 230. (www)

  @article{ , archive = {J_ApJ}, author = {Nathalie A. Korhonen Cuestas and Allison L. Strom and Tim B. Miller and Charles C. Steidel and Ryan F. Trainor and Gwen C. Rudie and Evan Haze Nuñez}, doi = {10.3847/1538-4357/adff60}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {230}, shortjournal = {The Astrophys. J.}, title = {Erratum: “Exploring the relationship between stellar mass, metallicity, and star formation rate at z ∼ 2.3 in KBSS-MOSFIRE” (2025, ApJ, 984, 188)}, volume = {990}, year = {2025}, }
• (2025). The ALMA survey of 70 μm dark high-mass clumps in early stages (ASHES). XII. unanchored forked stream in the propagating path of a protostellar outflow. ApJ, 990(2), 229. (www)

  @article{ , abstract = {Outflows are key indicators of ongoing star formation. We report the discovery of an unanchored forked stream within the propagating path of an extremely young protostellar outflow in the 70 μ m-dark clump G34.74-0.12, based on Atacama Large Millimeter/submillimeter Array (ALMA) 1.3 mm observations with an angular resolution of 1 \mathop{.}\limits^{^{\prime\prime} } 6 (∼5000 au). This outflow originates from a 9.7 M ⊙ core, exhibits a fork-shaped stream structure in its redshifted lobe, which is traced by CO (2–1), SiO (5–4), and H 2 CO (3 0,3 –2 0,2 ). It has a momentum of 13 M ⊙ km s −1 , an energy of 107 M ⊙ km 2 s −2 , and a dynamical timescale of ∼10 4 yr. Significantly, the enhanced relative abundances of SiO, H 2 CO, and CH 3 OH with respect to CO, along with the increased temperature at the forked point, indicate a collisional origin. The forked point does not coincide with any dust continuum core >0.1 M ⊙ . Moreover, CO (2–1) emission also traces three other outflows in this region, characterized by their masses (0.40, 0.02, and 0.15 M ⊙ ) and momenta (5.2, 0.2, and 1.8 M ⊙ km s −1 ), as part of the ALMA Survey of 70 μ m dark High-mass clumps in Early Stages project. All the newly discovered morphological and kinematic features associated with these extremely young protostellar outflows (with timescales of 10 3 –10 4 yr) suggest that the initial stages of star formation are more complicated than previously understood.}, archive = {J_ApJ}, author = {Shuting Lin and Siyi Feng and Patricio Sanhueza and Ke Wang and Zhi-Yu Zhang and Yichen Zhang and Fengwei Xu and Junzhi Wang and Kaho Morii and Hauyu Baobab Liu and Sheng-Yuan Liu and Lile Wang and Hui Li and Daniel Tafoya and Willem Baan and Shanghuo Li and Giovanni Sabatini}, doi = {10.3847/1538-4357/adf208}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {229}, shortjournal = {The Astrophys. J.}, title = {The ALMA survey of 70 μm dark high-mass clumps in early stages (ASHES). XII. unanchored forked stream in the propagating path of a protostellar outflow}, volume = {990}, year = {2025}, }
• (2025). Massive black hole seed formation in strong X-ray environments at high redshift. ApJ, 990(2), 228. (www)

  @article{ , abstract = {Direct collapse of pristine gas in early galaxies is a promising pathway for forming supermassive black holes (SMBHs) powering active galactic nuclei at the Epoch of Reionization (EoR). This seeding mechanism requires suppression of molecular hydrogen (H 2 ) cooling during primordial star formation via intense far-ultraviolet radiation from nearby starburst galaxies clustered in overdense regions. However, nondetection of 21 cm signals from the EoR reported by the Hydrogen Epoch of Reionization Array (HERA) experiment suggests that such galaxies may also emit X-rays more efficiently than in the local Universe, promoting H 2 production and thereby potentially quenching massive black hole (BH) seed formation. In this study, we examine the thermal and chemical evolution of collapsing gas in dark matter halos using a semi-analytic model incorporating observationally calibrated X-ray intensities. We find that strong X-ray irradiation, as suggested by HERA, significantly suppresses direct collapse and leads most halos to experience H 2 cooling. Nevertheless, massive BH seeds with M BH ≳ 10 4 M ⊙ still form by z ≃ 15, particularly in regions with baryonic streaming motion, and their abundance reaches ∼ 10 −4 Mpc −3 , sufficient to explain the SMBHs identified by James Webb Space Telescope spectroscopy at 3 < z < 6. While the formation of highly overmassive BHs with masses comparable to their host galaxies is prohibited by X-ray ionization, our model predicts that BH-to-stellar mass ratios of ≃0.01–0.1 were already established at seeding.}, archive = {J_ApJ}, author = {Kazutaka Kimura and Kohei Inayoshi and Kazuyuki Omukai}, doi = {10.3847/1538-4357/adf2ad}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {228}, shortjournal = {The Astrophys. J.}, title = {Massive black hole seed formation in strong X-ray environments at high redshift}, volume = {990}, year = {2025}, }
• (2025). The interplay of parametric and magnetorotational instabilities in oscillatory shear flows. ApJ, 990(2), 227. (www)

  @article{ , abstract = {The evolution of warped disks is governed by internal, oscillatory shear flows driven by their distorted geometry. However, these flows are known to be vigorously unstable to hydrodynamic parametric instability. In many warped systems, this might coexist and compete with the magnetorotational instability (MRI). The interplay of these phenomena and their combined impact on the internal flows has not been studied. To this end, we perform three-dimensional, magnetohydrodynamic unstratified shearing box simulations with an oscillatory radial forcing function to mimic the effects of a warped disk. In the hydrodynamic study, we find that the parametric instability manifests as strong, vertical “elevator” flows that resist the sloshing motion. Above a critical forcing amplitude, these also emerge in our magnetized runs and dominate the vertical stress, although they are partially weakened by the MRI, and hence the system equilibrates with larger radial sloshing flows. Below this critical forcing, the MRI effectively quenches the parametric instability. In all cases, we find that the internal stresses are anisotropic in character and better described by a viscoelastic relationship with the shearing flows. Unfortunately, these important effects are typically unresolved in global simulations of warped disks and are simplified in analytically tractable models. The incorporation of such complex, warp-amplitude-dependent, viscoelastic stresses will sensitively regulate the laminar flow response and inevitably modify the detailed spatio-temporal evolution of warped systems.}, archive = {J_ApJ}, author = {Callum W. Fairbairn and James M. Stone}, doi = {10.3847/1538-4357/adf4e1}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {227}, shortjournal = {The Astrophys. J.}, title = {The interplay of parametric and magnetorotational instabilities in oscillatory shear flows}, volume = {990}, year = {2025}, }
• (2025). Statistics of gas density, velocity, and magnetic fields in cool-core galaxy clusters. ApJ, 990(2), 226. (www)

  @article{ , abstract = {Understanding turbulence within the intracluster medium of galaxy clusters is pivotal for comprehending their evolution and dynamics. Employing 3D magnetohydrodynamic simulations of galaxy cluster mergers, we examine the statistical properties of gas density, magnetic fields, and velocity, particularly emphasizing the central regions spanning 400 kpc. The simulations are designed to resemble massive cool-core clusters such as Perseus, while varying the initial plasma β values (100, 200, and 500). Our findings indicate that while the statistical histogram distributions of gas density and velocity appear similar across different β scenarios, their spatial distributions and morphological patterns exhibit noticeable differences. Through the application of the second-order structure function, we identified a scaling relation in velocity fluctuations, characterized by a slope of 1/2 and predominantly dominated by solenoidal components. Furthermore, our analysis reveals a pronounced anisotropy in both velocity and magnetic field fluctuations, with more significant fluctuations along the direction perpendicular to the magnetic fields. This anisotropy is scale-dependent, becoming more pronounced at smaller scales, and exhibits a decreasing trend in scenarios where the magnetic field is relatively weak, particularly at β = 500. This suggests that the anisotropic nature of these fluctuations is predominantly regulated by the magnetic fields. Additionally, we test the efficacy of the synchrotron intensity gradient (SIG) method for tracing magnetic fields in these environments. The SIG shows a global agreement with the magnetic field across all three β scenarios, confirming the SIG’s insensitivity to the medium’s magnetization level.}, archive = {J_ApJ}, author = {Yue Hu and Alex Lazarian and Gianfranco Brunetti and John A. ZuHone}, doi = {10.3847/1538-4357/adf556}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {226}, shortjournal = {The Astrophys. J.}, title = {Statistics of gas density, velocity, and magnetic fields in cool-core galaxy clusters}, volume = {990}, year = {2025}, }
• (2025). Quantifying the impact of incompleteness on identifying and interpreting galaxy protocluster populations with the TNG-cluster simulation. ApJ, 990(2), 225. (www)

  @article{ , abstract = {We use the TNG-Cluster simulation to investigate how stellar mass and star formation rate (SFR) incompleteness affect the identification of density peaks within galaxy protoclusters at different redshifts. Our analysis focuses on a sample of 352 protoclusters, defined as the progenitor populations of galaxies that reside within the virialized region of z = 0 clusters with {M}_{\mathrm{200}}^{z=0}\sim 1{0}^{14.2-15.5}\,{M}_{\odot } . For comparison, we define our “baseline” protocluster population as galaxies with M ⋆ > 10 8.5 M ⊙ at any redshift. We find that M ⋆ -limited ( M ⋆ > 10 9.5 M ⊙ ) and SFR-limited (SFR > 10 M ⊙ yr −1 ) subpopulations recover the baseline highest galaxy density peak in roughly ∼60% of cases within an accuracy of 1.0 pMpc (corresponding to an angular scale of \sim {2}^{{\rm{{\prime} }}}-2\mathop{.}\limits^{{\rm{^{\prime} }}}5 ) at z > 2. This recovery fraction drops to ∼40%−50% when restricting to galaxies with M ⋆ > 10 10.0 M ⊙ . We find that the baseline highest galaxy density peaks typically coincide with the highest dark matter and stellar mass density peaks, with separations less than 0.5 pMpc in ∼60%−75% of cases at z > 2. This agreement drops to ∼45%−50% when restricting to galaxies with M ⋆ > 10 10.0 M ⊙ . These results indicate that identifying the densest regions of protoclusters—i.e., the core—is highly sensitive to stellar mass and SFR completeness limits. Nevertheless, at z > 2, we find that the baseline highest galaxy density peaks are generally sites of enhanced star formation and accelerated mass growth relative to the remainder of the protocluster, consistent with some observational studies.}, archive = {J_ApJ}, author = {Devontae C. Baxter and Alison L. Coil and Ethan O. Nadler and Dylan Nelson and Annalisa Pillepich and Ben Forrest and Finn Giddings and Emmet Golden-Marx and Brian C. Lemaux and Derek Sikorski}, doi = {10.3847/1538-4357/adf644}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {225}, shortjournal = {The Astrophys. J.}, title = {Quantifying the impact of incompleteness on identifying and interpreting galaxy protocluster populations with the TNG-cluster simulation}, volume = {990}, year = {2025}, }
• (2025). Effect of matter accretion on lithium enhancement of giants. ApJ, 990(2), 224. (www)

  @article{ , abstract = {A subset of low-mass giants (<2.2 M ⊙ ) exhibit anomalous lithium enhancement behavior, which is still an open topic. Given that more massive giants retain more surface lithium, increasing mass by accreting circumstellar matter could be a channel to enriching lithium. We evaluate this process in the current work. Using the Modules for Experiments in Stellar Astrophysics, we construct a model of matter accretion, including mass loss, that evolves a star from the main-sequence turnoff to the red giant branch tip. The mean accretion rate is estimated from the upper limit of the accreted mass and the evolutionary time of the star during this period, and a grid of accretion rates is constructed. We separately consider their effects on the lithium enhancement of giants, both in terms of the mass and the composition of accretion. Accreting matter with higher lithium abundances has a promoting effect on the lithium enhancement of giants. The accreted matter with excess lithium alleviates the dilution of lithium in the convective envelope during the first dredge-up. The added mass results in lower temperatures at the bottom of the convective envelope, which likewise weaken the depletion of surface lithium. The weak accretion of circumstellar matter is a possible route to lithium enhancement for giants, and it predicts an upper limit on the lithium abundance of ∼2.5 dex. However, the mass increment it requires poses a potential challenge to real astrophysical environments. Such accretion suppresses lithium dilution and depletion of the star during the first dredge-up, thus exhibiting lithium enhancement behavior.}, archive = {J_ApJ}, author = {Xue-Feng Li and Jian-Rong Shi and Yan Li and Hong-Liang Yan and Jing-Hua Zhang and Fei Guo}, doi = {10.3847/1538-4357/adf6b3}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {224}, shortjournal = {The Astrophys. J.}, title = {Effect of matter accretion on lithium enhancement of giants}, volume = {990}, year = {2025}, }
• (2025). Magnetic field amplification during a turbulent collapse. ApJ, 990(2), 223. (www)

  @article{ , abstract = {The question of whether a dynamo can be triggered by gravitational collapse is of great interest, especially for the early Universe. Here, we employ supercomoving coordinates to study the magnetic field amplification from decaying turbulence during gravitational collapse. We perform 3D simulations and show that for large magnetic Reynolds numbers, there can be exponential growth of the comoving magnetic field with conformal time before the decay of turbulence impedes further amplification. The collapse dynamics only affect the nonlinear feedback from the Lorentz force, which diminishes more rapidly for shorter collapse times, allowing nearly kinematic continued growth. We confirm that helical turbulence is more efficient in driving dynamo action than nonhelical turbulence, but this difference decreases for larger collapse times. We also show that for nearly irrotational flows, dynamo amplification is still possible, but it is always associated with a growth of vorticity—even if it still remains very small. In nonmagnetic runs, the growth of vorticity is associated with viscosity and grows with the Mach number. In the presence of magnetic fields, vorticity emerges from the curl of the Lorentz force. During a limited time interval, an exponential growth of the comoving magnetic field with conformal time is interpreted as clear evidence of dynamo action.}, archive = {J_ApJ}, author = {Axel Brandenburg and Evangelia Ntormousi}, doi = {10.3847/1538-4357/adf725}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {223}, shortjournal = {The Astrophys. J.}, title = {Magnetic field amplification during a turbulent collapse}, volume = {990}, year = {2025}, }
• (2025). Modeling blazar broadband emission with convolutional neural networks. III. proton synchrotron and hybrid models. ApJ, 990(2), 222. (www)

  @article{ , abstract = {Modeling the broadband emission of blazars has become increasingly challenging with the advent of multimessenger observations. Building upon previous successes in applying convolutional neural networks (CNNs) to leptonic emission scenarios, we present an efficient CNN-based approach for modeling blazar emission under proton synchrotron and hybrid lepto-hadronic frameworks. Our CNN is trained on extensive numerical simulations generated by SOPRANO , which span a comprehensive parameter space accounting for the injection and all significant cooling processes of electrons and protons. The trained CNN captures complex interactions involving both primary and secondary particles, effectively reproducing electromagnetic and neutrino emissions. This allows for rapid and thorough exploration of the parameter space characteristic of hadronic and hybrid emission scenarios. The effectiveness of the trained CNN is demonstrated through fitting the spectral energy distributions of two prominent blazars, TXS 0506+059 and PKS 0735+178, both associated with IceCube neutrino detections. The modeling is conducted under assumptions of constant neutrino flux across distinct energy ranges, as well as by adopting a fitting that incorporates the expected neutrino event count through a Poisson likelihood method. The trained CNN is integrated into the Markarian Multiwavelength Data Center ( www.mmdc.am ), offering a robust tool for the astrophysical community to explore blazar jet physics within a hadronic framework.}, archive = {J_ApJ}, author = {N. Sahakyan and D. Bégué and A. Casotto and H. Dereli-Bégué and V. Vardanyan and M. Khachatryan and P. Giommi and A. Pe’er}, doi = {10.3847/1538-4357/adf734}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {222}, shortjournal = {The Astrophys. J.}, title = {Modeling blazar broadband emission with convolutional neural networks. III. proton synchrotron and hybrid models}, volume = {990}, year = {2025}, }
• (2025). Spatially and dynamically extended molecular gas in stephan’s quintet revealed by ALMA CO(1–0) total power mapping. ApJ, 990(2), 221. (www)

  @article{ , abstract = {We present Atacama Large Millimeter/submillimeter Array Total Power CO(1–0) mapping of Stephan’s Quintet (SQ), a prototypical compact galaxy group, with a uniform noise level at a spatial scale of ∼25 kpc. These observations provide the first complete view of molecular gas across the whole system. Molecular gas is found to spread over a wide area (∼120 × 80 kpc), mainly over the two main member galaxies (NGC 7318B and 7319), but also in the shocked ridges between these galaxies, the tidal tail, and also in intergalactic regions north of the tail. The total CO(1–0) luminosity is (2.47 ± 0.12) × 10 9 K km s −1 pc 2 , corresponding to a molecular gas mass of (1.07 ± 0.05) × 10 10 M ⊙ assuming the Galactic CO-to-H 2 conversion factor. The global star formation efficiency of SQ is estimated at 0.29–0.70 Gyr −1 , comparable to or lower than that of nearby star-forming galaxies. Molecular gas spans a velocity range of ∼1300 km s −1 , which can be divided into three components (low, mid, and high). The low- and mid-velocity components, linked to NGC 7318B and the ridge, show relatively active star formation, whereas the high-velocity component, associated with NGC 7319, shows suppressed star formation. Our mapping reveals molecular gas extending ∼100 kpc in projection along the inner tail and north of it, containing (1.64 ± 0.08) × 10 9 M ⊙ (15% of total) with low velocity dispersion (∼20 km s −1 ) and ongoing star formation. While previous studies suggested in situ molecular gas formation in the tail, our data suggest an additional contribution from gas stripped from NGC 7319.}, archive = {J_ApJ}, author = {Fumiya Maeda and Shinya Komugi and Kazuyuki Muraoka and Misaki Yamamoto and Fumi Egusa and Kouji Ohta and Yoshihisa Asada and Asao Habe and Bunyo Hatsukade and Hiroyuki Kaneko and Masato I. N. Kobayashi and Kotaro Kohno and Ayu Konishi and Ren Matsusaka and Kana Morokuma-Matsui and Kouichiro Nakanishi and Tomoka Tosaki and Akiyoshi Tsujita}, doi = {10.3847/1538-4357/adfc56}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {221}, shortjournal = {The Astrophys. J.}, title = {Spatially and dynamically extended molecular gas in stephan’s quintet revealed by ALMA CO(1–0) total power mapping}, volume = {990}, year = {2025}, }
• (2025). Evaluating mass outflow rate estimators in FIRE-2 simulations: Toward a self-consistent framework for spectral-line-based predictions. ApJ, 990(2), 220. (www)

  @article{ , abstract = {Galactic outflows shape galaxy evolution, but their mass, energy, and momentum transfer remain uncertain. High-resolution spectroscopy can help, but systematic discrepancies hinder model interpretation. In this study, we evaluate the performance of semianalytical line transfer (SALT) and empirical partial covering models (PCMs) to recover the properties of outflows in the FIRE-2 simulation suite from synthetic Si II lines (1190 Å, 1193 Å, 1260 Å, 1304 Å, 1527 Å). When applicable, we assess each model’s ability to recover mass, energy, and momentum outflow rates, as well as radial density and velocity profiles, column densities, and flow geometries. We find that the PCM underestimates column densities by 1.3 dex on average in the range 15\lt {\mathrm{log}}\,N\,[{{\rm{cm}}}^{-2}]\lt 17 with dispersion 1.3 dex. We attribute this bias to instrumental smoothing. Since the PCM underestimates column densities, it also underestimates flow rates, though its predictions are independent of radius, with a dispersion of 0.55 dex. We detect no bias in the SALT estimates of the column density with dispersion 1.3 dex. When the velocity and density field obey power laws, SALT can constrain the mass, momentum, and energy outflow rates to 0.36(0.63), 0.56(0.56), and 0.97(0.80) dex at 0.15(0.30) R vir , respectively. However, certain profiles in FIRE-2 fall outside the SALT framework, where the model breaks down. We find that SALT effectively tracks the flow geometry, capturing the temporal evolution of the photon escape fraction that is out of phase with the star formation rate, fully consistent with hydrodynamic simulations. We advocate for integral field unit spectroscopy to better constrain flow properties.}, archive = {J_ApJ}, author = {Cody A. Carr and Aaron Smith and Viraj Pandya and Christopher C. Hayward and Mason Huberty and Claudia Scarlata and Renyue Cen}, doi = {10.3847/1538-4357/adf4c2}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {220}, shortjournal = {The Astrophys. J.}, title = {Evaluating mass outflow rate estimators in FIRE-2 simulations: Toward a self-consistent framework for spectral-line-based predictions}, volume = {990}, year = {2025}, }
• (2025). Quasiperiodic oscillation signatures of disk restoration after type-I X-ray bursts from 4U 1636−536. ApJ, 990(2), 219. (www)

  @article{ , abstract = {Type-I thermonuclear bursts (TNBs) from neutron star low-mass X-ray binaries (NS LMXBs) originate on the neutron star’s surface from the unstable burning of the accreted material. On the other hand, kHz quasiperiodic oscillations (QPOs) are thought to originate in the innermost regions of the inspiralling accretion disk. Type-I TNBs are expected to impact the inner accretion flow, and consequently the kHz QPOs, due to the intense radiation pressure. In this work, we systematically study the evolution of the upper and the lower kHz QPOs immediately before and after a type-I TNB on 4U 1636−536 using AstroSat observations in the 3–20 keV band. The analysis of the power density spectra shows the presence of kHz QPOs within 200 s before the onset of the type-I burst. However, we have not detected any prominent signature of the same within 100–200 s after the burst. The kHz QPOs then reemerge after ≈200 s. The fractional rms variation in the 3–20 keV band drops by ≈5%–6%, supporting the nonexistence of kHz QPOs in the 200 s postburst zone. The timescale of 200 s coincides with the viscous timescale, highlighting a scenario where the inner disk is temporarily disrupted by the intense radiation from the type-I TNB. The kHz QPO then reestablishes as the inner disk is restored.}, archive = {J_ApJ}, author = {Suchismito Chattopadhyay and Jaiverdhan Chauhan and Ranjeev Misra and Anne Lohfink and Rhaana Starling and Priya Bharali and Soma Mandal}, doi = {10.3847/1538-4357/adf63a}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {219}, shortjournal = {The Astrophys. J.}, title = {Quasiperiodic oscillation signatures of disk restoration after type-I X-ray bursts from 4U 1636−536}, volume = {990}, year = {2025}, }
• (2025). A comprehensive analysis of X-ray sources in terzan 5 using chandra observations. ApJ, 990(2), 218. (www)

  @article{ , abstract = {We analyze photometry, spectra, and variability of over 100 faint X-ray sources in the globular cluster Terzan 5, using 737 ks of Chandra data. X-ray colors and spectral fitting allow for clear separation of foreground sources (with less extinction than the cluster), quiescent low-mass X-ray binaries (qLMXBs), and sources with harder spectra. We identify 22 candidate qLMXBs, over twice that found in any other cluster. This is consistent with Terzan 5’s stellar interaction rate, the highest among Galactic globular clusters. We do not see qLMXBs dominated by thermal emission below L X ∼ 10 32 erg s −1 , though qLMXBs with stronger nonthermal emission could be missed. We find that more than 50% of the qLMXB sources have a neutron star thermal component contributing over 80% of the total luminosity. We report an unusual spectral feature around 1.75 keV in the combined spectrum of Ter 5 X-3. The concentration of the qLMXBs within the cluster is consistent with that of a population of mass 1.46 ± 0.14 M ⊙ . We identify secure X-ray counterparts to millisecond pulsars Terzan 5 ar and Terzan 5 at, using positional coincidence and orbital X-ray light curves matching those expected for spider pulsars.}, archive = {J_ApJ}, author = {Gourav Kumawat and Craig O. Heinke and Jiaqi Zhao and Arash Bahramian and Haldan N. Cohn and Phyllis M. Lugger}, doi = {10.3847/1538-4357/adf724}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {218}, shortjournal = {The Astrophys. J.}, title = {A comprehensive analysis of X-ray sources in terzan 5 using chandra observations}, volume = {990}, year = {2025}, }
• (2025). McFACTS i: Testing the LVK AGN channel with monte carlo for AGN channel testing and simulation (McFACTS). ApJ, 990(2), 217. (www)

  @article{ , abstract = {Active galactic nuclei (AGNs) are a promising source of the binary black hole mergers observed in gravitational waves with LIGO-Virgo-Kagra (LVK). Constraining the AGN channel allows us to limit AGN parameter space (disk density, size, average lifetime) and nuclear star cluster (NSC) parameter space. Constraints on AGNs and NSCs have implications for Λ cold dark matter models of AGN feedback and models of AGN-driven supermassive black hole merger and growth. Here we present several qualitative studies of the AGN channel using new public, open-source, fast, reproducible code McFACTS ( https://github.com/mcfacts/mcfacts ): Monte Carlo for AGN channel Testing and Simulation. We demonstrate several important features for testing the AGN channel, including: (i) growth to large-mass intermediate-mass black hole is helped by the presence of migration traps or swamps, (ii) flat BH initial mass functions highlight hierarchical merger features in the mass spectrum, (iii) the ( q , χ eff ) anticorrelation is a strong test of the bias to prograde mergers in the AGN channel, (iv) spheroid encounters can drive a fraction of mergers with high in-plane spin components ( χ p ), (v) a high rate of extreme mass ratio inspirals are driven by an initial population of embedded retrograde BH, and (vi) both LVK and LISA are powerful probes of models of AGN disks and their embedded populations.}, archive = {J_ApJ}, author = {Barry McKernan and K.E. Saavik Ford and Harrison E. Cook and Vera Delfavero and Emily McPike and Kaila Nathaniel and Jake Postiglione and Shawn Ray and Richard O’Shaughnessy}, doi = {10.3847/1538-4357/adf114}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {217}, shortjournal = {The Astrophys. J.}, title = {McFACTS i: Testing the LVK AGN channel with monte carlo for AGN channel testing and simulation (McFACTS)}, volume = {990}, year = {2025}, }
• (2025). The lockman-SpReSo project. spectroscopic analysis of type 1 active galactic nuclei. ApJ, 990(2), 216. (www)

  @article{ , abstract = {We present the first optical-UV spectral systematic analysis of 30 Type 1 active galactic nuclei selected in the far-infrared and X-ray in the Lockman-SpReSO Survey. The sample of faint objects ( m B = 19.6–21.8) covers a large redshift range of 0.33 > z > 4.97 with a high signal-to-noise ratio (∼21 on average). A detailed spectral analysis based on the quasar main-sequence phenomenology prescription was applied to deblend the principal optical-UV emitting regions. Our sample spans a bolometric luminosity range of 44.85 < log L bol < 47.87, absolute B -magnitude of 20.46 > M B > –26.14, BH mass of 7.59 < log M BH < 9.80, and Eddington ratio of –1.70 < log R Edd < 0.56. The analysis shows that 18 high- z objects correspond to Population (Pop) B, whereas three low- z fall in Pop A2, B1, and B1+. The remaining eight are candidates to be Pop B and one Pop A object. None of them is an extreme accretor. We looked for tendencies in our sample and compared them with other samples with different selection criteria. Evidence for winds was explored using the C iv λ 1549 line half-height centroid c (1/2), finding wind velocities between 941 and −1587 km s −1 . This result is consistent with samples with similar ranges of z and M B . The Baldwin effect showed a slope of –0.23 ± 0.03 dex consistent with previous studies. Spectra from 12 objects in our sample were found in the Sloan Digital Sky Survey Data Release 17 database. We applied the same methodology to compare them to our spectra, finding no evidence of variability.}, archive = {J_ApJ}, author = {Castalia Alenka Negrete and Héctor J. Ibarra-Medel and Erika Benítez and Irene Cruz-González and Yair Krongold and J. Jesús González and Jordi Cepa and Carmen Padilla-Torres and Miguel Cerviño and Mirjana Povic and Martín Herrera-Endoqui and Nancy Jenaro-Ballesteros and Takamitsu Miyaji and Mauricio Elías-Chávez and Miguel Sánchez-Portal and Bernabé Cedrés and Jakub Nadolny and Mauro González-Otero and Bereket Assefa and Héctor Hernández-Toledo and J. Antonio de Diego and J. Ignacio González-Serrano and A. M. Pérez-García}, doi = {10.3847/1538-4357/adf189}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {216}, shortjournal = {The Astrophys. J.}, title = {The lockman-SpReSo project. spectroscopic analysis of type 1 active galactic nuclei}, volume = {990}, year = {2025}, }
• (2025). Spectropolarimetry of GRB 180427A: Evidence for distinct emission sites with varying polarization. ApJ, 990(2), 215. (www)

  @article{ , abstract = {The dynamics of the origin of gamma-ray emissions in gamma-ray bursts (GRBs) remains an enigma. Through a joint analysis of GRB 180427A, observed by the Fermi Gamma-ray Space Telescope and AstroSat’s Cadmium Zinc Telluride Imager, we identify emissions from two distinct regions with varying polarization properties. Time-resolved polarization analysis reveals a synchronous evolution of the polarization angle (PA) and fraction with two emission pulses, peaking with a delay of 5.09 ± 0.29 s. Spectral analysis indicates that the first pulse is characterized by a stronger blackbody component, while the second pulse exhibits a more prominent nonthermal spectrum (power law with an exponential cutoff). Using a bottom-to-top approach through simulations, we decouple the polarization properties of the individual spectral components, revealing polarization fractions (PFs) of 25%–40% for the blackbody spectrum and 30%–60% for the nonthermal spectrum. At a redshift of z ∼ 0.22, the blackbody emission originates from the jet photosphere at ∼a few 10 11 cm, whereas the nonthermal emission arises from an optically thin region at a few 10 13 cm. The changing dominance of these emissions explains the observed PA shift of 60° ± 22°. The spectral cutoff at 1 MeV suggests pair opacity due to the jet’s relatively lower bulk Lorentz factor (Γ∼ a few tens). The high PF and hard low-energy spectral slopes ( α > −0.5) imply a top-hat jet structure observed off-axis, near the jet’s edge. This off-axis viewing introduces anisotropy in the observed radiation within the viewing cone (1/Γ), accounting for the observed polarization.}, archive = {J_ApJ}, author = {Rushikesh Sonawane and Shabnam Iyyani and Soumya Gupta and Tanmoy Chattopadhyay and Dipankar Bhattacharya and Varun. B. Bhalerao and Santosh V. Vadawale and G. C. Dewangan}, doi = {10.3847/1538-4357/adf43e}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {215}, shortjournal = {The Astrophys. J.}, title = {Spectropolarimetry of GRB 180427A: Evidence for distinct emission sites with varying polarization}, volume = {990}, year = {2025}, }
• (2025). Multiband optical variability of the blazar OP 313 in the outburst state during 2024–2025. ApJ, 990(2), 214. (www)

  @article{ , abstract = {We present the analysis results of flux and spectral variability of the blazar OP 313 across intra-night to short-term timescales using BVRI photometric data, gathered over 25 nights from 2024 November to 2025 May, using two optical telescopes in Aryabhatta Research Institute of Observational Sciences, India. The source was in an outburst state during this period. We searched for intraday variability (IDV), using two powerful statistical tests: the power-enhanced F-test and the nested ANOVA test. The source displayed IDV in the R band for five of the 10 nights, yielding a duty cycle of 34%. During the entire monitoring of the source, it showed variations of over two mag in all B , V , R , and I data bands. We obtained a variability timescale for a variable light curve, giving us an upper limit for the size of the emission region. We generated optical spectral energy distributions of the blazar for these 25 nights, fitted a power law of form ( F {}_{\nu }\propto {\nu }^{-{\alpha }_{o}} ) and found the weighted mean spectral index to be 1.471 ± 0.004. An analysis of the color–magnitude diagram shows that, contrary to the redder-when-brighter trend typically observed in FSRQs, this source exhibits a bluer-when-brighter trend on short-term variability timescales—a behavior more commonly associated with BL Lac objects. We explore potential physical mechanisms responsible for the observed spectral variability.}, archive = {J_ApJ}, author = {P. U. Devanand and Alok C. Gupta and Karan Dogra and Shubham Kishore and Tushar Tripathi}, doi = {10.3847/1538-4357/adf4c3}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {214}, shortjournal = {The Astrophys. J.}, title = {Multiband optical variability of the blazar OP 313 in the outburst state during 2024–2025}, volume = {990}, year = {2025}, }
• (2025). GeV gamma-rays from molecular clouds illuminated by particles diffusing from the adjacent supernova remnant g335.2+0.1 confined in an expanding bubble. ApJ, 990(2), 213. (www)

  @article{ , abstract = {We report the detection of GeV gamma-ray emission likely associated with supernova remnant (SNR) G335.2+0.1 and the finding of a molecular cloud (∼20′– 30^{\prime} in angular size) that is very likely in physical contact with the SNR and responsible for the gamma-ray emission. Using the 16.8 yr Fermi-LAT data, an extended emission, with a significance of 13.5 σ and a radius 0 \mathop{.}\limits^{\unicode{x000b0}} 24 in 0.2–500 GeV in the uniform-disk model, was found to the adjacent east of the SNR. With archival Mopra CO-line data, a large molecular clump at local-standard-of-rest velocity ∼−48 to −43 km s −1 was revealed, appearing coincident with the gamma-ray source. The SNR was found located in a cavity encircled by a “C”-shaped ring-like molecular shell at −45 to −43 km s −1 . This morphological agreement, together with the position-velocity diagrams made along lines cutting across the cavity, suggests that the SNR was evolving in the expanding molecular bubble created by the stellar wind of the progenitor with a mass ≳15 M ⊙ . The giant molecular cloud, visible at around −46 km s −1 , and the associated SNR are thus estimated to lie at a kinematic distance of 3.1 kpc, with the H i absorption taken into account. We suggest that the SNR has entered the radiative phase after the blastwave recently struck the cavity wall. With the evolutionary scenario of the SNR, we demonstrate that the gamma-ray emission reported here can be naturally interpreted by the hadronic interaction between the accelerated protons escaped from the SNR shock and the eastern large molecular clump.}, archive = {J_ApJ}, author = {Chen Huang and Xiao Zhang and Yang Chen and Qian-Qian Zhang and Wen-Juan Zhong and Xin Zhou}, doi = {10.3847/1538-4357/adf4d8}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {213}, shortjournal = {The Astrophys. J.}, title = {GeV gamma-rays from molecular clouds illuminated by particles diffusing from the adjacent supernova remnant g335.2+0.1 confined in an expanding bubble}, volume = {990}, year = {2025}, }
• (2025). Understanding the transport properties of Methane–Hydrogen mixtures under the interior conditions of ice giants. ApJ, 990(2), 212. (www)

  @article{ , abstract = {Inaccuracy in our knowledge of the transport properties of relevant mixtures under planetary interior conditions is a roadblock in predicting the observable properties of planets in our solar system and beyond. In this work, we investigate methane–hydrogen mixtures using data sets obtained from density functional theory calculations for the electronic structure, combined with molecular dynamics simulations for the ions for a wide range of pressure and temperature. Hydrogen concentration significantly affects the equation of state (EOS) but has little influence on transport properties. We provide an analytical expression to model thermal EOS and transport properties as a function of hydrogen content, with the maximum deviation observed at low P – T conditions. These insights are particularly relevant to improve the planetary models and enhance our ability to predict the properties of “ice” giants and beyond.}, archive = {J_ApJ}, author = {Argha Jyoti Roy and Mandy Bethkenhagen and Armin Bergermann and Ronald Redmer}, doi = {10.3847/1538-4357/adf5be}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {212}, shortjournal = {The Astrophys. J.}, title = {Understanding the transport properties of Methane–Hydrogen mixtures under the interior conditions of ice giants}, volume = {990}, year = {2025}, }
• (2025). Gravitational-wave phase shifts in eccentric black hole mergers as a probe of dynamical formation environments. ApJ, 990(2), 211. (www)

  @article{ , abstract = {We here quantify the gravitational-wave (GW) phase shift appearing in the waveform of eccentric binary black hole (BBH) mergers formed dynamically in 3-body systems. For this, we have developed a novel numerical method where we construct a reference binary, by evolving the post-Newtonian ( { \mathcal P }N ) evolution equations backwards from a point near merger without the inclusion of the third object, that can be compared to the perturbed binary that evolves under the influence from the third BH. From this, we quantify how the interplay between dynamical tides, { \mathcal P }N -effects, and the time-dependent Doppler shift of the eccentric GW source results in unique observable GW phase shifts that can be used to probe the dynamical assembly mechanism of individual GW sources. We further find an analytical expression for the GW phase shift, which has a universal functional form that only depends on the time-evolving BBH eccentricity. The normalization scales with the BH masses and initial separation, which can be linked to the underlying astrophysical environment. GW phase shifts from a chaotic 3-body BH scattering taking place in a cluster, and from a BBH inspiraling in a disk migration trap near a supermassive BH, are also shown for illustration.}, archive = {J_ApJ}, author = {Johan Samsing and Kai Hendriks and Lorenz Zwick and Daniel J. D’Orazio and Bin Liu}, doi = {10.3847/1538-4357/ad9f3d}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {211}, shortjournal = {The Astrophys. J.}, title = {Gravitational-wave phase shifts in eccentric black hole mergers as a probe of dynamical formation environments}, volume = {990}, year = {2025}, }
• (2025). Scattering of stellar mass black holes and gravitational-wave bremsstrahlung radiation in active galactic nucleus disks. ApJ, 990(2), 210. (www)

  @article{ , abstract = {The dynamics of stellar mass black holes (sBHs) embedded in active galactic nuclei (AGNs) could produce highly eccentric orbits near the central supermassive black hole, leading to repeated close encounters that emit gravitational waves in the Laser Interferometer Gravitational-Wave Observatory (LIGO) frequency band. Many works have focused on the mergers of sBHs in the disk that produce gravitational waves; however, sBHs in hyperbolic orbits also emit gravitational-wave bremsstrahlung that can be detected by ground-based interferometers like LIGO. In this work, we analyze the scattering of sBHs in an AGN disk as they migrate inside the disk, focusing on gravitational-wave bremsstrahlung emission. We determine how the gravitational-wave emission depends on the different parameters of the scattering experiments, such as the mass of the supermassive black hole and the sBH migration rate and mass ratio. We find that scattering with detectable gravitational-wave bremsstrahlung is more frequent around lower-mass supermassive black holes (∼10 5−6 M ⊙ ). We then conduct a suite of Monte Carlo simulations and estimate the rate for ground-based gravitational-wave detections to be in the range of 0.08–1194 Gpc −3 yr −1 , depending on migration forces and detection thresholds, with large uncertainties accounting for variations in possible AGN environments. The expected rate for our Fiducial parameters is 3.2 Gpc −3 yr −1 . Finally, we provide first-principle gravitational-wave templates produced by the encounters.}, archive = {J_ApJ}, author = {Peter Lott and Christian Faulhaber and Joshua Brandt and Gongjie Li and Hareesh Bhaskar and Laura Cadonati}, doi = {10.3847/1538-4357/adcd5e}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {210}, shortjournal = {The Astrophys. J.}, title = {Scattering of stellar mass black holes and gravitational-wave bremsstrahlung radiation in active galactic nucleus disks}, volume = {990}, year = {2025}, }
• (2025). The resolved structure of a low-metallicity photodissociation region. ApJ, 990(2), 209. (www)

  @article{ , abstract = {Photodissociation regions (PDRs) are key to understanding the feedback processes that shape interstellar matter in galaxies. One important type of PDR is the interface between H ii regions and molecular clouds, where far-ultraviolet radiation from massive stars heats gas and dissociates molecules. Photochemical models predict that as metallicity decreases, the C/CO transition occurs at greater depths in the PDR compared to the H/H 2 transition, increasing the extent of CO-dark H 2 gas in low-metallicity environments. This prediction has been difficult to test outside the Milky Way due to the lack of high-spatial-resolution observations tracing H 2 and CO. This study examines a low-metallicity PDR in the N13 region of the Small Magellanic Cloud (SMC), where we spatially resolve the ionization front, the H 2 dissociation front, and the C/CO transition using 12 CO J = 2−1, 3−2, and [C I ] 1–0 observations from the Atacama Large Millimeter/submillimeter Array and near-infrared spectroscopy of the H 2 2.12 1–0 S(1) vibrational line, and H recombination lines from the James Webb Space Telescope. Our analysis shows that the separation between the H/H 2 and C/CO boundaries is approximately 0.043 ± 0.013(stat.) ± 0.0036(syst.) pc (equivalent to 0\mathop{.}\limits^{^{\prime\prime} }146\pm 0\mathop{.}\limits^{^{\prime\prime} }042({\rm{stat.}})\pm 0\mathop{.}\limits^{^{\prime\prime} }012({\rm{syst.}}) at the SMC’s distance of 62 kpc), defining the spatial extent of the CO-dark H 2 region. Compared to our plane-parallel PDR models, we find that a constant-pressure model matches the observed structure better than a constant-density one. Overall, we find that the PDR model does well at predicting the extent of the CO-dark H 2 layer in N13. This study represents the first resolved benchmark for low-metallicity PDRs.}, archive = {J_ApJ}, author = {Ilyse Y. Clark and Karin Sandstrom and Mark Wolfire and Alberto D. Bolatto and Jérémy Chastenet and Daniel A. Dale and Brandt A. L. Gaches and Simon C. O. Glover and Javier R. Goicoechea and Karl D. Gordon and Brent Groves and Lindsey Hands and Ralf Klessen and Ilse De Looze and J. D. T. Smith and Dries Van De Putte and Stefanie K. Walch}, doi = {10.3847/1538-4357/adef38}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {209}, shortjournal = {The Astrophys. J.}, title = {The resolved structure of a low-metallicity photodissociation region}, volume = {990}, year = {2025}, }
• (2025). Extremely tenuous, dusty terrestrial atmospheres remain stable against global collapse: An argument for arid planet habitability in the trappist-1 system. ApJ, 990(2), 208. (www)

  @article{ , abstract = {The potential habitability of tidally locked planets orbiting M stars remains uncertain. However, recent observations with JWST and numerous theoretical studies investigating atmospheric evolution over time suggest that thick atmospheres (>1 bar) with abundant surface water are increasingly unlikely. A significant challenge to habitability for tidally locked systems is the prevention of atmospheric collapse. For tenuous atmospheres, this challenge is even more extreme, since low-pressure atmospheres cannot transport heat effectively from the day- to nightside. Previous studies find that collapse is likely for CO 2 atmospheres with surface pressures less than 100 mbar for planets in the habitable zone of Trappist-1, which would significantly reduce the likelihood for long-term habitability in that system. In this study, we find that modest levels of atmospheric mineral dust mitigate this collapse for a tenuous 7.05 mbar atmosphere on a small Mars-sized planet. Dust heating modifies the vertical and zonal thermal gradients and wind sheers. Due to the rapid planetary rotation (1 yr = 6 sols), this change is reflected in the magnitude of rotational components of the global circulation, including the equatorial jet and midlatitude eddies. We find that heat transport by these components is increased in dusty simulations, and atmospheric collapse on the permanent nightside is prevented. This dust-dominated climate is consistent with a planetary atmosphere evolving towards low pressure and high aridity with time. Our findings therefore provide an alternative target to Earth-like climates around M stars and reopens the possibility of habitability in M star systems.}, archive = {J_ApJ}, author = {Victoria L. Hartwick and Melinda A. Kahre and Robert M. Haberle}, doi = {10.3847/1538-4357/adf42f}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {208}, shortjournal = {The Astrophys. J.}, title = {Extremely tenuous, dusty terrestrial atmospheres remain stable against global collapse: An argument for arid planet habitability in the trappist-1 system}, volume = {990}, year = {2025}, }
• (2025). Revisiting the perseus cluster. i. resolving the Si/S/Ar/Ca ratios by stellar convection. ApJ, 990(2), 207. (www)

  @article{ , abstract = {Chemical abundance measurements from stars in the Milky Way to the intragalactic medium in the Perseus Cluster have challenged the spherical explosion models. Models in the literature cannot closely match the observed element ratios, where Si, S are overproduced and Ar, Ca are underproduced. In this article, we explore the impact of the model parameters during the evolution of massive stars on the final explosive nucleosynthesis. We investigate the effects of a parameterized model of the convective process, including the mixing length parameter and the semiconvection parameter, on the production of Si-group elements. We search for the value pair that can reduce the discrepancy in the models. We conclude that a mixing length parameter of 2.2 and a semiconvection parameter of 0.03 are required to fit these criteria. Using this updated value pair, we compute a sequence of massive star models from M ZAMS = 15–40 M ⊙ . The high-resolution data from future observations, such as XRISM, will provide further details on less constrained processes in stellar evolution and supernova explosions. Future comparison with supernova models of various progenitor metallicity will further shed light on the supernova population and their relative rates on cosmological scales.}, archive = {J_ApJ}, author = {Shing-Chi Leung and Ken’ichi Nomoto and Aurora Simionescu}, doi = {10.3847/1538-4357/adf430}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {207}, shortjournal = {The Astrophys. J.}, title = {Revisiting the perseus cluster. i. resolving the Si/S/Ar/Ca ratios by stellar convection}, volume = {990}, year = {2025}, }
• (2025). The most distant γ-ray flare to date: A multiwavelength campaign on the z = 4.715 blazar GB6 b1428+4217. ApJ, 990(2), 206. (www)

  @article{ , abstract = {In 2023 November, the Fermi Large Area Telescope detected a γ -ray flare from the high-redshift blazar GB6 B1428+4217 ( z = 4.715). We initiated a multiwavelength follow-up campaign involving Swift, NuSTAR, the Sierra Nevada and Perkins Observatories, and the Effelsberg 100 m radio telescope. This source, also known as 5BZQ J1430+4204, has shown an anomalous soft X-ray spectrum in previous observations, including possible ionized absorption features or signatures of bulk Comptonization of thermal electrons, which are also detected during the flaring episode. Simultaneous optical data revealed a polarization fraction of ∼8% in the R band, confirming that synchrotron emission dominated over thermal emission from the accretion disk. The hard X-ray flux was enhanced during the flare. Modeling of the broadband spectral energy distribution suggests that the high-energy component is dominated by Compton scattering by external seed photons from the accretion disk. The origin of the flare is consistent with the injection of a hard-spectrum electron population in the emission region. With a γ -ray luminosity among the top 5% of flaring events, GB6 B1428+4217 exemplifies a prototypical MeV blazar. Its Compton-dominated spectral energy distribution and extreme luminosity are in line with expectations from the blazar sequence. High-redshift flares like this are critical for understanding jet physics in the early Universe and may improve detection prospects with future missions such as the Compton Spectrometer and Imager.}, archive = {J_ApJ}, author = {Andrea Gokus and Manel Errando and Ivan Agudo and Markus Böttcher and Florian Eppel and Juan Escudero Pedrosa and Jonas Heßdörfer and Svetlana Jorstad and Matthias Kadler and Alex Kraus and Michael Kreter and Felicia McBride and Daniel Morcuende and Jorge Otero-Santos and Jörn Wilms}, doi = {10.3847/1538-4357/adf4d2}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {206}, shortjournal = {The Astrophys. J.}, title = {The most distant γ-ray flare to date: A multiwavelength campaign on the z = 4.715 blazar GB6 b1428+4217}, volume = {990}, year = {2025}, }
• (2025). Spectral biases, starspot morphology, and dynamo transitions on the pre-main sequence: Insights from the X-shooter WTTS library. ApJ, 990(2), 205. (www)

  @article{ , abstract = {Starspots are ubiquitous in young, low-mass stars, yet their impact on the spectral classification and fundamental parameter inference of pre-main-sequence stars (PMS) has been largely overlooked. In this study, we demonstrate that cool starspots systematically distort spectral morphology and bias the effective temperatures, surface gravities, and luminosities derived for nonaccreting weak-lined T Tauri stars (WTTSs). Using a sample of 56 WTTSs with high-resolution, broadband X-Shooter spectra, we perform two-temperature spectral fits that explicitly account for spot coverages and temperature contrasts. These composite models consistently outperform traditional single-temperature fits, particularly in the 3350–4000 K regime, where spot contributions dominate the red-optical and near-IR flux. Moreover, we propose that surface gravity discrepancies between optical and IR measurements are a natural consequence of spot-dominated emission in PMS stars. We find that single-temperature models can overestimate effective temperatures by up to 700 K and underestimate {\mathrm{log}}\,g by 1–2 dex. Using spot-corrected effective temperatures, we derive masses and ages from traditional, magnetic, and spotted evolutionary models, finding that spot corrections systematically raise inferred masses by up to 80% and stellar ages by up to 0.5 dex. These discrepancies are strongest for stars in the 0.3–0.8 M ⊙ range. Using starspots as a proxy for magnetic topology, we find evidence that a shift from largely axisymmetric to nonaxisymmetric magnetic fields dominated by small-scale structures coincides with the formation of a radiative core during PMS evolution, effectively distinguishing between the convective and interface dynamo regimes.}, archive = {J_ApJ}, author = {Facundo Pérez Paolino and Jeffrey S. Bary and Lynne A. Hillenbrand and Benjamin Horner and Adolfo Carvalho}, doi = {10.3847/1538-4357/adf6ad}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {205}, shortjournal = {The Astrophys. J.}, title = {Spectral biases, starspot morphology, and dynamo transitions on the pre-main sequence: Insights from the X-shooter WTTS library}, volume = {990}, year = {2025}, }
• (2025). New insights into the t tauri binary separation distribution. ApJ, 990(2), 204. (www)

  @article{ , abstract = {For three decades, adaptive optic surveys have revealed an excess of T Tauri binaries across a = 10–100 au in nearby star-forming regions compared to the field population of main-sequence (MS) stars. Such an excess requires that most stars are born in dense clusters and subjected to significant dynamical processing that disrupts such binaries across intermediate separations. However, we demonstrate that the apparent excess is due to an observational selection bias. Close binaries within a < 100 au clear out their dusty circumstellar disks on faster timescales compared to wide binaries and single stars. A magnitude-limited sample is therefore biased toward close binaries that have preferentially cleared out their obscuring disks. We reexamine the separation distribution of pre-MS binaries in low-density Taurus, moderately dense Upper Scorpius (Upper Sco), and the extremely dense Orion Nebula Cluster (ONC). By limiting the samples to primary spectral type/mass instead of magnitude, the artificial excess across a = 10–100 au disappears in all three environments. Across wider separations a = 100–4000 au, Taurus exhibits an excess of companions (mostly tertiaries), the ONC displays a deficit, and Upper Sco matches the field MS population. The field derives from an amalgam of all three environments, where Upper Sco corresponds to the average birth environment of solar-type stars. The total binary fraction within a < 10,000 au in Taurus is only 52% ± 7%, substantially lower than the 100% inferred from the biased observations and only slightly higher than the field MS value of 45%. N -body interactions preferentially disrupt outer tertiaries with only marginal dynamical processing of the inner binaries, especially those within a < 100 au.}, archive = {J_ApJ}, author = {Caleb Eastlund and Maxwell Moe and Kaitlin M. Kratter and Marina Kounkel}, doi = {10.3847/1538-4357/adf6bc}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {204}, shortjournal = {The Astrophys. J.}, title = {New insights into the t tauri binary separation distribution}, volume = {990}, year = {2025}, }
• (2025). A galactic self-portrait: Density structure and integrated properties of the milky way disk. ApJ, 990(2), 203. (www)

  @article{ , abstract = {The evolutionary history of the Milky Way disk is imprinted in the ages, positions, and chemical compositions of individual stars. In this study, we derive the intrinsic density distribution of different stellar populations using the final data release of the Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey. A total of 203,197 red giant branch stars are used to sort the stellar disk ( R ≤ 20 kpc) into subpopulations of metallicity (Δ[M/H]  = 0.1 dex), age ( {{\rm{\Delta }}}\,{\mathrm{log}}\,(\frac{{{\rm{age}}}}{{{\rm{yr}}}})\,=\,0.1 ), and α -element abundances ([ α /M]). We fit the present-day structural parameters and density distribution of each stellar subpopulation after correcting for the survey selection function. The low- α disk is characterized by longer scale lengths and shorter scale heights, and is best fit by a broken exponential radial profile for each population. The high- α disk is characterized by shorter scale lengths and larger scale heights, and is generally well-approximated by a single exponential radial profile. These results are applied to produce new estimates of the integrated properties of the Milky Way from early times to the present day. We measure the total stellar mass of the disk to be 5.2{7}_{-1.5}^{+0.2}\times 1{0}^{10} M ⊙ , and the average mass-weighted scale length is R d = 2.37 ± 0.2 kpc. The Milky Way’s present-day color of ( g − r ) = 0.72 ± 0.02 is consistent with the classification of a red spiral galaxy, although it has only been in the “green valley” region of the galaxy color–mass diagram for the last ∼3 Gyr.}, archive = {J_ApJ}, author = {Julie Imig and Jon A. Holtzman and Gail Zasowski and Jianhui Lian and Nicholas F. Boardman and Alexander Stone-Martinez and J. Ted Mackereth and Moire K. M. Prescott and Rachael L. Beaton and Timothy C. Beers and Dmitry Bizyaev and Michael R. Blanton and Katia Cunha and José G. Fernández-Trincado and Catherine E. Fielder and Sten Hasselquist and Christian R. Hayes and Misha Haywood and Henrik Jönsson and Richard R. Lane and Steven R. Majewski and Szabolcs Mészáros and Ivan Minchev and David L. Nidever and Christian Nitschelm and Jennifer Sobeck}, doi = {10.3847/1538-4357/adf723}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {203}, shortjournal = {The Astrophys. J.}, title = {A galactic self-portrait: Density structure and integrated properties of the milky way disk}, volume = {990}, year = {2025}, }
• (2025). Fast radio bursts by stellar wind microlensing of a faint background source. ApJ, 990(2), 202. (www)

  @article{ , abstract = {By assuming the inverse square law of solar wind plasma density as representative of other stars, it is shown that just outside a star, the outward deflection of a passing radio signal at ν ≈ 1 GHz (which is capable of penetrating the plasma) is about 5 times larger than the gravitational inward deflection by the star, and the ensuing lens equation, which takes both effects into account is a cubic polynomial with three roots and a new strong lensing caustic. The geometric optics approach is valid for a radio source size ≲1 pc. Microlensing magnification of a steady background source occurs typically over a timescale of milliseconds, resulting in ≈80 fast radio bursts (FRBs) per day over the whole sky, which can only perturb the isotropy of FRB distribution at the several percent level. Moreover, repeating FRBs could be triggered by the periodic interception of the line of sight of the background source by members of a binary system. The temporal signatures of such FRBs are consistent with the power spectrum of solar wind density fluctuations on corresponding scales, except that the mean density of the wind is a few times higher than the solar value.}, archive = {J_ApJ}, author = {Richard Lieu}, doi = {10.3847/1538-4357/adf73b}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {202}, shortjournal = {The Astrophys. J.}, title = {Fast radio bursts by stellar wind microlensing of a faint background source}, volume = {990}, year = {2025}, }
• (2025). The ATLAS virtual research assistant. ApJ, 990(2), 201. (www)

  @article{ , abstract = {We present the Virtual Research Assistant (VRA) of the ATLAS sky survey, which performs preliminary eyeballing on our clean transient data stream. The VRA uses histogram-based gradient-boosted decision tree classifiers trained on real data to score incoming alerts on two axes: “Real” and “Galactic.” The alerts are then ranked using a geometric distance such that the most “real” and “extragalactic” receive high scores; the scores are updated when new lightcurve data is obtained on subsequent visits. To assess the quality of the training we use the recall at rank K , which is more informative to our science goal than general metrics (e.g., accuracy, F1-scores). We also establish benchmarks for our metric based on the pre-VRA eyeballing strategy, to ensure our models provide notable improvements before being added to the ATLAS pipeline. Then, policies are defined on the ranked list to select the most promising alerts for humans to eyeball and to automatically remove bogus alerts. In production the VRA method has resulted in a reduction in eyeballing workload by 85% with a loss of follow-up opportunity <0.08%. It also allows us to automatically trigger follow-up observations with the Lesedi telescope, paving the way toward automated methods that will be required in the era of LSST. Finally, this is a demonstration that feature-based methods remain extremely relevant in our field, being trainable on only a few thousand samples and highly interpretable; they also offer a direct way to inject expertise into models through feature engineering.}, archive = {J_ApJ}, author = {H. F. Stevance and K. W. Smith and S. J. Smartt and S. J. Roberts and N. Erasmus and D. R. Young and A. Clocchiatti}, doi = {10.3847/1538-4357/adf2a1}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {201}, shortjournal = {The Astrophys. J.}, title = {The ATLAS virtual research assistant}, volume = {990}, year = {2025}, }
• (2025). Determining the magnetic field in the atmosphere of a solar active region observed by the CLASP2.1 sounding rocket experiment. ApJ, 990(2), 200. (www)

  @article{ , abstract = {We determine magnetic fields from the photosphere to the upper chromosphere combining data from the Hinode satellite and the CLASP2.1 sounding rocket experiment. CLASP2.1 provided polarization profiles of the Mg ii h and k lines, as well as of the Mn i lines around 2800 Å, across various magnetic structures in an active region, containing a plage, a pore, and the edges of a sunspot penumbra. By applying the weak-field approximation to the circular polarization profiles of these spectral lines, we obtain a longitudinal magnetic field map at three different heights in the chromosphere (lower, middle, and upper). This is complemented by data from Hinode (photospheric magnetic field), the Interface Region Imaging Spectrograph, and the Solar Dynamics Observatory (high spatial resolution observations of the chromosphere and corona). We quantify the height expansion of the plage magnetic fields and find that the magnetic fields expand significantly in the middle chromosphere, shaping the moss observed above in the transition region and corona. We identified an area with polarity reversal at the upper chromosphere around the edge of the pore, suggesting the presence of a magnetic discontinuity in the upper chromosphere. Transient and recurrent jetlike events are observed in this region, likely driven by magnetic reconnection. Around the penumbral edge, we find large-scale magnetic fields corresponding to the superpenumbral fibrils seen in the upper chromosphere. In the superpenumbral fibrils, we find Zeeman-induced linear polarization signals, suggesting the presence of a significantly inclined magnetic field, as strong as 1000 G in the upper chromosphere.}, archive = {J_ApJ}, author = {Ryohko Ishikawa and Javier Trujillo Bueno and David E. McKenzie and Donguk Song and Tanausú del Pino Alemán and Ernest Alsina Ballester and Luca Belluzzi and Hao Li and Frédéric Auchère and Christian Bethge and Bart De Pontieu and Ryouhei Kano and Ken Kobayashi and Adam R. Kobelski and Takenori J. Okamoto and Laurel A. Rachmeler and Taro Sakao and Jiří Štěpán and Genevieve D. Vigil and Amy Winebarger}, doi = {10.3847/1538-4357/aded0e}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {200}, shortjournal = {The Astrophys. J.}, title = {Determining the magnetic field in the atmosphere of a solar active region observed by the CLASP2.1 sounding rocket experiment}, volume = {990}, year = {2025}, }
• (2025). Dynamical stability of hypermassive neutron stars against quasi-radial perturbations. ApJ, 990(2), 199. (www)

  @article{ , abstract = {The dynamical stability of differentially rotating neutron stars, including hypermassive neutron stars, is of paramount importance in understanding the fate of the postmerger remnant of binary neutron stars mergers and the formation of a black hole during core-collapse supernovae. We study systematically the dynamical stability of differentially rotating neutron stars within a broad range of masses, rotation rates, and degrees of differential rotation, modeled as polytropes with Γ = 2. We pay particular attention to quasi-toroidal configurations that are outside the parameter space region explored in previous works. We estimate the limits of the region of stability against quasi-radial perturbations by performing an extensive set of numerical simulations. We find that some of the stability criteria proposed in the past are not sufficient or necessary to determine stability if differential rotation is present, and propose a new, more general criterion. We show that there is a large parameter space that allows for quasi-toroidal configurations that will not collapse immediately to a black hole and that can sustain masses up to ∼2.5 times the maximum mass of a nonrotating neutron star.}, archive = {J_ApJ}, author = {Paweł Szewczyk and Dorota Gondek-Rosińska and Pablo Cerdá-Durán}, doi = {10.3847/1538-4357/adee12}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {199}, shortjournal = {The Astrophys. J.}, title = {Dynamical stability of hypermassive neutron stars against quasi-radial perturbations}, volume = {990}, year = {2025}, }
• (2025). Modeling tidal disruptions with dynamical tides. ApJ, 990(2), 198. (www)

  @article{ , abstract = {Tidal disruption events (TDEs) occur when stars pass close enough to supermassive black holes to be torn apart by tidal forces. Traditionally, these events are studied with computationally intensive hydrodynamical simulations. In this paper, we present a fast, physically motivated two-stage model for TDEs. In the first stage, we model the star’s tidal deformation using linear stellar perturbation theory, treating the star as a collection of driven harmonic oscillators. When the tidal energy exceeds a fraction γ of the star’s gravitational binding energy (with \gamma \sim { \mathcal O }(1) ), we transition to the second stage, where we model the disrupted material as free particles. The parameter γ is determined with a one-time calibration to the critical impact parameter obtained in hydrodynamical simulations. This method enables fast computation of the energy distribution d M / d E and fallback rate d M / d T while offering physical insight into the disruption process. We apply our model to MESA-generated profiles of middle-age main-sequence stars. Our code is available on GitHub ( https://github.com/ZihanZhou26/PerTDE ).}, archive = {J_ApJ}, author = {Zihan Zhou and Giovanni Maria Tomaselli and Irvin Martínez-Rodríguez and Jingping Li}, doi = {10.3847/1538-4357/adf190}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {198}, shortjournal = {The Astrophys. J.}, title = {Modeling tidal disruptions with dynamical tides}, volume = {990}, year = {2025}, }
• (2025). Redshift evolution of the intrinsic alignments of early-type galaxies and subhalos in the horizon run 5 simulation. ApJ, 990(2), 197. (www)

  @article{ , abstract = {We investigate the redshift evolution of intrinsic alignments (IAs) of the shapes of galaxies and subhalos with the large-scale structures of the Universe using the cosmological hydrodynamic simulation, Horizon Run 5. To this end, early-type galaxies are selected from the simulated galaxy catalogs based on stellar mass and kinematic morphology. The shapes of galaxies and subhalos are computed using the reduced inertia tensor derived from mass-weighted particle positions. We find that the misalignment between galaxies and their corresponding dark matter subhalos decreases over time. We further analyze the two-point correlation between galaxy or subhalo shapes and the large-scale density field traced by their spatial distribution, and quantify the amplitude using the nonlinear alignment model across a wide redshift range from z =  0.625 to z =  2.5. We find that the IA amplitude, A NLA , of galaxies remains largely constant with redshift, whereas that of dark matter subhalos exhibits moderate redshift evolution, with a power-law slope that deviates from zero at a significance level exceeding 3 σ . Additionally, A NLA is found to depend on both the stellar mass and kinematic morphology of galaxies. Notably, our results are broadly consistent with existing observational constraints. Our findings are in good agreement with previous results of other cosmological simulations.}, archive = {J_ApJ}, author = {Sanghyeon Han and Motonari Tonegawa and Ho Seong Hwang and Yohan Dubois and Juhan Kim and Yonghwi Kim and Oh-Kyoung Kwon and Jaehyun Lee and Owain N. Snaith and Brad K. Gibson and Changbom Park}, doi = {10.3847/1538-4357/adf33b}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {197}, shortjournal = {The Astrophys. J.}, title = {Redshift evolution of the intrinsic alignments of early-type galaxies and subhalos in the horizon run 5 simulation}, volume = {990}, year = {2025}, }
• (2025). A new framework for understanding systematic errors in cluster lens modeling. IV. constraints from the giant arc in abell 370. ApJ, 990(2), 196. (www)

  @article{ , abstract = {We aim to improve cluster lens modeling and source reconstruction by utilizing the full information in giant, caustic-crossing arcs lensed by galaxy clusters. Lens models are generally constrained using image positions and assuming point sources, but spatially extended giant arcs provide more constraints; however, they require a more complex model that accounts for the structure of the extended source. We seek to determine whether improvements to the lens model and reconstructed source merit the difficulty of handling the extra constraints. We choose the spatially extended z = 0.725 giant arc in the z = 0.375 Abell 370 galaxy cluster field for our study. We present (1) a series of pixel-based source reconstructions (PBSRs) for cluster mass models exploring the range of uncertainties in our fiducial model, (2) a similar analysis done using a prototype Python de-lensing code for cluster mass models from each of the Hubble Frontier Fields (HFF) modeling teams, (3) an optimized model with PBSR, and (4) and an investigation of how our optimized model affects the cluster mass model locally and globally in the highest-magnification regions. We find that our optimized model (1) is able to correct resolution-limited assumptions in cluster model inputs local to the arc, (2) has significantly smaller arc model residuals than results from the standard HFF models, and (3) affects the critical curves and therefore the information derived from highest-magnification zones most significantly in regions local to the arc.}, archive = {J_ApJ}, author = {Lana Eid and Charles R. Keeton}, doi = {10.3847/1538-4357/adf4cb}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {196}, shortjournal = {The Astrophys. J.}, title = {A new framework for understanding systematic errors in cluster lens modeling. IV. constraints from the giant arc in abell 370}, volume = {990}, year = {2025}, }
• (2025). Bifrost models of the quiet sun. i. comparison with solar observations. ApJ, 990(2), 195. (www)

  @article{ , abstract = {Studying the emergence of magnetic fields is essential for understanding the physical mechanisms behind various phenomena in the solar atmosphere. Most importantly, the emerging fields offer valuable insights into how energy and mass are transferred to the upper solar atmosphere. As a result, they have garnered significant attention from both observational and theoretical perspectives. In this article, we present two models of quiet-Sun-like magnetic fields generated by the Bifrost code. We compare these models with observations from the Swedish 1 m Solar Telescope (SST) and the Interface Region Imaging Spectrograph (IRIS). By tracking the magnetic features in both the SST and Bifrost data, we determine the similarities and differences between the fields identified in the models and those observed. We conduct a quantitative comparison of various properties, such as flux content, flux densities, horizontal and line-of-sight velocities, lifetimes, sizes, and surface interactions. Additionally, we identify and analyze the properties of the largest emerging bipoles in the SST and Bifrost data. Our findings indicate that the magnetic bipoles in the Bifrost simulations are generally stronger than those observed with the SST. However, a qualitative comparison of the chromospheric and transition region responses to the emerging fields in the Bifrost models, SST, and IRIS observations shows similar heating processes occurring above and around the emerging fields. Finally, we outline our plans for future work aimed at studying the emergence of magnetic fields in the quiet Sun, with a particular focus on the chromosphere and upper atmospheric layers.}, archive = {J_ApJ}, author = {M. Gošić and V. H. Hansteen and A. Sainz Dalda and B. De Pontieu and L. H. M. Rouppe van der Voort}, doi = {10.3847/1538-4357/adf4db}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {195}, shortjournal = {The Astrophys. J.}, title = {Bifrost models of the quiet sun. i. comparison with solar observations}, volume = {990}, year = {2025}, }
• (2025). X-ray halos of early-type galaxies with active galactic nucleus feedback and accretion from a circumgalactic medium: Models and observations. ApJ, 990(2), 194. (www)

  @article{ , abstract = {Knowledge of the X-ray properties of the hot-gas halos of early-type galaxies (ETGs) has significantly advanced in the past years, for large and homogeneously investigated samples. We compare these results with the X-ray properties of an exploratory set of gas evolution models in realistic ETGs, produced with our high-resolution 2D hydrodynamical code MACER that includes active galactic nucleus feedback and accretion from a circumgalactic medium. The model X-ray emission and absorption are integrated along the line of sight, to obtain maps of the surface brightness Σ X and temperature T X . The X-ray diagnostics considered are the luminosity and average temperature for the whole galaxy ( L X and 〈 T X 〉) and within five optical effective radii ( L X,5 and 〈 T X,5 〉) and the circularized profiles Σ X ( R ) and T X ( R ). The values for L X , L X,5 , 〈 T X 〉, and 〈 T X,5 〉 compare very well with those observed. The Σ X ( R ) and T X ( R ) also present qualitative similarities with those of the representative galaxy NGC 5129 and those of ETGs with the most commonly observed shape for T X ( R ): Σ X ( R ) matches the observed profile over many optical effective radii R e , and T X ( R ) reproduces the characteristic bump that peaks at R = (1 ÷ 3) R e . Inside the peak position, T X ( R ) declines toward the center, but the explored models are systematically hotter by ≃30%; possible explanations for this discrepancy are discussed. Interestingly, Σ X ( R ) and T X ( R ) as large as those observed outside R ≃ R e are reproduced only with significant accretion from a circumgalactic medium, highlighting its importance.}, archive = {J_ApJ}, author = {Silvia Pellegrini and Luca Ciotti and Zhaoming Gan and Dong-Woo Kim and Jeremiah P. Ostriker}, doi = {10.3847/1538-4357/adf5c1}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {194}, shortjournal = {The Astrophys. J.}, title = {X-ray halos of early-type galaxies with active galactic nucleus feedback and accretion from a circumgalactic medium: Models and observations}, volume = {990}, year = {2025}, }
• (2025). First detection of circular polarization in 4.7 GHz excited OH masers. ApJ, 990(2), 193. (www)

  @article{ , abstract = {We report the first detection of circular polarization in 4.7 GHz excited OH masers in star-forming regions made using full Stokes measurements with the Green Bank 100 m telescope. The Zeeman shift between the two circular components provides a measure of the magnetic field pervading these maser spots. Three different methods are used to determine the shift in velocity between the RCP and LCP components. We find fields with B ∼ 100 mG using archival molecular parameters that have limited precision and uncertain values. Reservations of using 1.7 and 6.0 GHz OH masers to estimate magnetic fields in star-forming regions are discussed.}, archive = {J_ApJ}, author = {Derck P. Smits and Paul Fallon}, doi = {10.3847/1538-4357/adf639}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {193}, shortjournal = {The Astrophys. J.}, title = {First detection of circular polarization in 4.7 GHz excited OH masers}, volume = {990}, year = {2025}, }
• (2025). Statistical analysis of polycyclic aromatic hydrocarbons as a tracer of anomalous microwave emission using DIRBE data. ApJ, 990(2), 192. (www)

  @article{ , abstract = {We use archival data from the Diffuse Infrared Background Experiment (DIRBE) to map the polycyclic aromatic hydrocarbon (PAH) 3.3 μ m emission feature and analyze its correlation with anomalous microwave emission (AME) in 98 compact sources identified by the Planck collaboration. We find that while far-IR thermal dust emission continues to be a better tracer of AME in most of the considered regions, 17% of the AME sources are better correlated with emission from small PAHs as traced by DIRBE. Furthermore, of the 27 sources that were identified as highly significant AME detections in the Planck analysis, 37% prefer PAHs as an AME tracer. Further work is required to understand to what extent local interstellar conditions are affecting PAH emission mechanisms and to reveal the underlying carriers of AME.}, archive = {J_ApJ}, author = {Danielle Sponseller and David T. Chuss and Brandon Hensley and Alan Kogut}, doi = {10.3847/1538-4357/adf72e}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {192}, shortjournal = {The Astrophys. J.}, title = {Statistical analysis of polycyclic aromatic hydrocarbons as a tracer of anomalous microwave emission using DIRBE data}, volume = {990}, year = {2025}, }
• (2025). Inside the stagnation radius of the nearest billion-solar-mass black hole. ApJ, 990(2), 191. (www)

  @article{ , abstract = {We used the NSF Jansky Very Large Array at a frequency ν = 22 GHz to study the nearest billion-solar-mass black hole (BH), in the early-type galaxy NGC 3115 at a distance of 9.7 Mpc. We localize a faint continuum nucleus, with flux density S 22 GHz = 48.2 ± 6.4 μ Jy, to a FWHM diameter d 22 GHz < 59 mas (2.8 pc). We find no evidence for adjacent emission within a stagnation region of radius R sta ∼ 360 mas (17 pc) identified in a recent hydrodynamic simulation tailored to NGC 3115. Within that region, the simulated gas flow developed into an advection-dominated accretion flow (ADAF). The nucleus’ luminosity density L 22 GHz = 5.4 × 10 17 W Hz −1 is about 60 times that of Sagittarius A ⋆ . The nucleus’ spectral index {\alpha }_{10\,{\rm{GHz}}}^{22\,{\rm{GHz}}}=-1.85\pm 0.18 ( S ν ∝ ν α ) indicates optically thin synchrotron emission. The spectral energy distribution of the nucleus peaks near ν peak = 9 GHz. Modeling this radio peak as an ADAF implies a BH mass M ADAF = (1.2 ± 0.2) × 10 9 M ⊙ , consistent with previous estimates of (1–2) × 10 9 M ⊙ from stellar or hot-gas dynamics. Also, the Eddington-scaled accretion rate for NGC 3115, {\dot{M}}_{{\rm{ADAF}}}/{\dot{M}}_{{\rm{Edd}}}=1.{2}_{-0.6}^{+1.0}\times 1{0}^{-8} , is about 4–8 times lower than recent estimates for Sagittarius A ⋆ .}, archive = {J_ApJ}, author = {J. M. Wrobel and D. W. Pesce and K. E. Nyland}, doi = {10.3847/1538-4357/adfa93}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {191}, shortjournal = {The Astrophys. J.}, title = {Inside the stagnation radius of the nearest billion-solar-mass black hole}, volume = {990}, year = {2025}, }
• (2025). An equipotential disk model with irradiation for nova-like variables. ApJ, 990(2), 190. (www)

  @article{ , abstract = {The reflection effect is here incorporated within an earlier analytic binary system light- and velocity-curve model that includes a circumstellar equipotential disk. The modeled disk is semitransparent, to explore the attenuation and reemission of irradiance within the disk, as well as the irradiance of the companion star. The reflection functions defined in R. E. Wilson ensure efficient computation and allow multiple reflection. A capsule summary of the general binary system potential problem provides a foundation for close binary morphological ideas. Chief among these ideas is that many or perhaps most postnovae may be of the double contact morphological type. The location of an outer-disk null point of effective gravity accurately quantifies a limit on disk size. The disk should not extend beyond the outer null point, as the local material would then be unbound to the disk. The disk’s inner extent is set by another null point. The inner and outer null locations are computed at each solution iteration, thus obviating any need for the arbitrary cutoffs seen in other postnova disk models. Remarkably, impersonal light-curve solutions find the disk edge quite close to the outer null point for U Scorpii (U Sco). Other reflection-related topics include irradiation heating and measurement of disk interior density and temperature. Analyses find white dwarf masses about 3%–6% lower than in nongravitating disk models that implicitly include disk mass as part of the white dwarf. The results from CI Aquilae and U Sco analyses are tabulated and prospects for further progress are outlined.}, archive = {J_ApJ}, author = {R. E. Wilson and W. Van Hamme}, doi = {10.3847/1538-4357/adee1a}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {190}, shortjournal = {The Astrophys. J.}, title = {An equipotential disk model with irradiation for nova-like variables}, volume = {990}, year = {2025}, }
• (2025). Methyl isocyanate formation from oxygen insertion in methyl cyanide ices. ApJ, 990(2), 189. (www)

  @article{ , abstract = {In cold molecular clouds, UV photolysis of icy grain mantles generates radicals that lead to new molecule formation. When radical diffusion is limited by low temperatures, oxygen atom addition and insertion reactions, enabled by photolysis of common ice components such as H 2 O, CO 2 , CO, and O 3 , offer an alternative route to chemical complexity through the production of metastable, highly reactive O( 1 D) atoms. We examine the reactivity of these oxygen atoms generated by UV photolysis of O 3 with methyl cyanide (CH 3 CN). These studies are conducted in an ultra-high vacuum chamber at cryogenic and low-pressure conditions equipped with in situ infrared spectroscopy to monitor destruction and product formation in real time. We conclude that oxygen atoms rapidly insert into CH 3 CN to produce primarily methyl isocyanate (CH 3 NCO) in matrix-free ices. Over the range from 10 to 40 K, we observe no temperature dependence to either CH 3 CN destruction or CH 3 NCO production. When placing CH 3 CN:O 3 in H 2 O and CO 2 ice matrices, we find that CH 3 NCO formation remains robust, but that the yield likely decreases due to competing reaction pathways. In the case of the H 2 O ice, we also observe a shift in product branching ratios toward alternative pathways such as the formation of hydroxyacetonitrile (HOCH 2 CN). Overall, our results demonstrate that oxygen atom reactivity provides an important channel for generating chemical complexity from nitriles on cold grains where radical mobility is limited.}, archive = {J_ApJ}, author = {Michelle R. Brann and Mahesh Rajappan and Karin I. Öberg}, doi = {10.3847/1538-4357/adf3aa}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {189}, shortjournal = {The Astrophys. J.}, title = {Methyl isocyanate formation from oxygen insertion in methyl cyanide ices}, volume = {990}, year = {2025}, }
• (2025). HST observations of the cataclysmic variable propeller LAMOST j024048.51+195226.9. ApJ, 990(2), 188. (www)

  @article{ , abstract = {We present Hubble Space Telescope (HST) far-UV spectra and light curves of the magnetic cataclysmic variable (CV) LAMOST J024048.51+195226.9 (J0240), the second known CV propeller. The five consecutive HST orbits span a full 7.34 hr binary orbital period. We detect a 24.939 ± 0.006 s far-UV modulation, confirming that J0240 contains the fastest spinning white dwarf (WD) in a CV. A high N v /C iv emission line ratio is considered an indicator of a recent episode of thermal-timescale mass transfer. The observed ratio in J0240 is higher than seen in typical magnetic CVs, but far less than observed in the only other confirmed propeller, AE Aquarii (AE Aqr). We also find that J0240 is significantly less luminous than AE Aqr during both low- and high-flux states. Around orbital phase 0.5, the Si iv emission line displays a P-Cygni absorption profile, likely related to the gas accelerated in the propeller. We derive new mass-dependent limits for the surface temperature of the WD of T ≤ 11,000–15,000 K. This temperature is low enough to allow for WD core crystallization, which may be linked to magnetism in WDs, particularly those in CVs.}, archive = {J_ApJ}, author = {Jordan Tweddale and Peter Garnavich and Colin Littlefield and Paula Szkody}, doi = {10.3847/1538-4357/adf3ae}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {188}, shortjournal = {The Astrophys. J.}, title = {HST observations of the cataclysmic variable propeller LAMOST j024048.51+195226.9}, volume = {990}, year = {2025}, }
• (2025). Formation of organic hazes in CO2-rich sub-neptune atmospheres within the graphite stability regime. ApJ, 990(2), 187. (www)

  @article{ , abstract = {Super-Earths and sub-Neptunes are the most common exoplanets, with a “radius valley” suggesting that super-Earths may form by shedding sub-Neptunes’ gaseous envelopes. Exoplanets that lie closer to the super-Earth side of the valley are more likely to have lost a significant fraction of their original H/He envelopes and become enriched in heavier elements, with CO 2 gaining in abundance. It remains unclear which types of haze would form in such atmospheres, potentially significantly affecting spectroscopic observations. To investigate this, we performed laboratory simulations of two CO 2 -rich gas mixtures (with 2000 times solar metallicity at 300 and 500 K). We found that under plasma irradiation organic hazes were produced at both temperatures, with a higher haze production rate at 300 K, probably because condensation occurs more readily at lower temperature. Gas-phase analysis demonstrates the formation of various hydrocarbons, oxygen- and nitrogen-containing species, including reactive gas precursors like C 2 H 4 , CH 2 O, and HCN, for haze formation. The compositional analysis of the haze particles reveals various functional groups and molecular formulas in both samples. The 500 K haze sample has larger average molecular sizes, a higher degree of unsaturation with more double or triple bonds present, and higher nitrogen content incorporated as N–H and C=N bonds, indicating different haze formation pathways. These findings not only improve the haze formation theories in CO 2 -rich exoplanet atmospheres but also offer important implications for the interpretation of future observational data.}, archive = {J_ApJ}, author = {Sai Wang and Zhengbo Yang and Chao He and Haixin Li and Yu Liu and Yingjian Wang and Xiao’ou Luo and Sarah E. Moran and Cara Pesciotta and Sarah M. Hörst and Julianne I. Moses and Véronique Vuitton and Laurène Flandinet}, doi = {10.3847/1538-4357/adfa0a}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {187}, shortjournal = {The Astrophys. J.}, title = {Formation of organic hazes in CO2-rich sub-neptune atmospheres within the graphite stability regime}, volume = {990}, year = {2025}, }
• (2025). Elemental abundances in X-ray binary outflows. ApJ, 990(2), 186. (www)

  @article{ , abstract = {Line-resolved X-ray spectra of outflows from X-ray binaries are interesting since they provide quantifiable measures of the accreted material onto the compact object (black hole or neutron star), which can not be observed directly in the accretion disk. One such measurement that has been largely overlooked is that of the elemental abundances, which potentially provide insights into the origin of the ejected material. Using the Chandra/HETG grating spectrometer we measure and present elemental abundances in four low-mass X-ray binaries. We compare two measurement methods. One is by fitting line series of individual ions and reconstructing the absorption measure distribution (AMD), and the other is a global fit with one or two individual ionization components. All outflows feature a steep AMD strongly favoring high ionization degrees. The present abundances are consistent with previous works suggesting the abundances in the outflows are nonsolar. We find a tentative trend of increasing abundances with atomic number, which fits some core-collapse supernova models, but there is no exact match to a specific one.}, archive = {J_ApJ}, author = {Noa Keshet and Ehud Behar and Jon M. Miller}, doi = {10.3847/1538-4357/adfa9b}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {186}, shortjournal = {The Astrophys. J.}, title = {Elemental abundances in X-ray binary outflows}, volume = {990}, year = {2025}, }
• (2025). Correlation of burst behavior with magnetar age. ApJ, 990(2), 185. (www)

  @article{ , abstract = {We analyze a wide set of historical magnetar burst observations detected with five different instruments, calibrating these to the energy range of Fermi-GBM observations for consistency. We find a striking correlation between a magnetar’s characteristic age and both its typical burst energy and its burst activity level. Arguing that this bursting behavior also correlates with true age, we interpret it as the result of a reducing high-stress volume of the crust in an aging magnetar: Previous giant flares cause relaxation of large regions of its crust and inhibit burst clustering, while the reducing burst energy reflects the progressively shallower region of the crust where Hall drift can build stresses effectively, as the field decays through the range ∼10 12 –10 13 G. Low-energy bursts from very young magnetars may represent failures of weak regions of the crust that have only recently solidified.}, archive = {J_ApJ}, author = {Özge Keskin and Samuel K. Lander and Ersin Göğüş}, doi = {10.3847/1538-4357/ade991}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {185}, shortjournal = {The Astrophys. J.}, title = {Correlation of burst behavior with magnetar age}, volume = {990}, year = {2025}, }
• (2025). Dissecting bar-induced stellar kinematics in disk galaxies: The bisymmetric model and rotation curve modifications. ApJ, 990(2), 184. (www)

  @article{ , abstract = {We analyze bars formed in N -body simulations to investigate two key aspects of stellar kinematic structure of barred galaxies: the angular distributions of the radial and azimuthal components of stellar velocities, and the impact of bars on rotation curves. We find that stars on bar-supporting x 1 -like orbits exhibit characteristic sawtooth-like radial velocity patterns and archlike tangential velocity patterns as a function of azimuth. In contrast, stars on box and disk orbits show little azimuthal variation, effectively smoothing the overall velocity distribution. When averaged over all orbital families, the resulting kinematics are broadly consistent with the bisymmetric model of Sellwood and Spekkens, with the amplitudes of bar-induced velocity perturbations increasing with bar strength. In addition, bars amplify the radial pressure gradient associated with enhanced random stellar motions, leading to a noticeable reduction in the mean rotational velocity. This effect becomes more pronounced with increasing bar strength, resulting in a shallower rotation curve within the bar region. We discuss our results in the context of the kinematic properties of observed barred galaxies.}, archive = {J_ApJ}, author = {Seungwon Baek and Woong-Tae Kim and Dajeong Jang and Taehyun Kim}, doi = {10.3847/1538-4357/adf213}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {184}, shortjournal = {The Astrophys. J.}, title = {Dissecting bar-induced stellar kinematics in disk galaxies: The bisymmetric model and rotation curve modifications}, volume = {990}, year = {2025}, }
• (2025). Multiwavelength dust characterization of the HL tau disk and implications for planet formation. ApJ, 990(2), 183. (www)

  @article{ , abstract = {We present a comprehensive analysis of the HL Tau dust disk by modeling its intensity profiles across six wavelengths (0.45–7.9 mm) with a resolution of 0 \mathop{.}\limits^{^{\prime\prime} } 05 (∼7 au). Using a Markov Chain Monte Carlo (MCMC) approach, we constrain key dust properties, including temperature, surface density, maximum grain size, composition, filling factor, and size distribution. The full fitting, with all parameters free, shows a preference for organics-rich dust with a low filling factor in the outer region ( r ≳ 40 au), where the spectral index is ∼3.7, but amorphous-carbon-rich dust also reasonably reproduces the observed intensity profiles. Considering the scattering polarization observed at 0.87 mm, compact, amorphous-carbon-rich dust is unlikely and moderately porous dust is favored. Beyond 40 au, the maximum dust size is likely ∼100 μ m if dust is compact or amorphous-carbon rich. However, if the dust is moderately porous and organics-rich, both the predicted dust surface density and dust size can be sufficiently large for the pebble accretion rate to reach ∼10 M ⊕ Myr −1 in most regions, suggesting that pebble accretion could be a key mechanism for forming planets in the disk. In contrast, if the dust is amorphous-carbon-rich, forming a giant planet core via pebble accretion is unlikely due to the combined effects of low dust surface density and small dust size required to match the observed emission, suggesting other mechanisms, such as disk fragmentation due to gravitational instability, may be responsible for planet formation in the HL Tau disk.}, archive = {J_ApJ}, author = {Takahiro Ueda and Sean M. Andrews and Carlos Carrasco-González and Osmar M. Guerra-Alvarado and Satoshi Okuzumi and Ryo Tazaki and Akimasa Kataoka}, doi = {10.3847/1538-4357/adf214}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {183}, shortjournal = {The Astrophys. J.}, title = {Multiwavelength dust characterization of the HL tau disk and implications for planet formation}, volume = {990}, year = {2025}, }
• (2025). Milky way mass through escape velocity curve from LAMOST k giants. ApJ, 990(2), 182. (www)

  @article{ , abstract = {Escape velocity has long been used to constrain the mass of the dark matter (DM) halo in the Milky Way (MW). Here, we present a study of the escape velocity curve using a sample of high-velocity K giants with full 6D phase-space information and of relatively good quality, selected from LAMOST DR8 and cross-matched with Gaia DR3. To expand the high-velocity stars to larger distances, we used radius-dependent criteria of total velocity, i.e., v GC > 300 km s −1 for the solar neighborhood and {v}_{{\rm{GC}}}\gt {v}_{{\rm{\min }}}\sim 0.6\times {v}_{{\rm{esc}}}({r}_{{\rm{GC}}}) for the outer region. We also selected halo stars based on v ϕ − [Fe/H] information to ensure that the sample is isotropic. We modeled the velocity distribution with traditional power-law models to determine the escape velocity in each radial bin. For the first time, we have directly measured a relatively continuous escape velocity curve that can extend to Galactocentric radii of ∼50 kpc, finding a decline in agreement with previous studies. The escape velocity at the solar position yielded by our measurements is 523.7{4}_{-13.47}^{+12.83}\,{\rm{km}}\,{{\rm{s}}}^{-1} . Combined with the local circular velocity, we estimated the mass of the MW assuming a Navarro–Frenk–White DM profile, which resulted in a total mass of {M}_{200,\,{\rm{total}}}=0.9{0}_{-0.07}^{+0.06}\times 1{0}^{12}\,{M}_{\odot } , with a concentration of {c}_{200}=13.4{7}_{-1.70}^{+1.85} . The small uncertainty implies that including the escape velocities beyond the solar neighborhood can result in a more precise mass estimate. Our derived MW mass is consistent with some recent studies using the escape velocity as well as other tracers, which may support a lower mass of the DM halo than in the past.}, archive = {J_ApJ}, author = {Yin Wu and Haining Li and Yang Huang and Xiang-Xiang Xue and Gang Zhao}, doi = {10.3847/1538-4357/adf2a4}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {182}, shortjournal = {The Astrophys. J.}, title = {Milky way mass through escape velocity curve from LAMOST k giants}, volume = {990}, year = {2025}, }
• (2025). Evolution of a coronal mass ejection with an eruptive prominence from the corona to interplanetary space. ApJ, 990(2), 181. (www)

  @article{ , abstract = {Understanding the location and evolution of the cool dense prominence in relation to the large-scale structure of coronal mass ejections (CMEs) is critical to distinguish between different CME initiation mechanisms and to further deepen our understanding of CME evolution through the heliosphere. Combining remote observations of extreme-ultraviolet images and white-light coronagraphs and heliospheric imagers (HIs) obtained from the Solar Dynamics Observatory, Solar and Heliospheric Observatory, STEREO-A, and Solar Orbiter, we present an analysis of the continuous tracking from the corona to interplanetary space of the substructures of a CME associated with a prominence that erupted on 2022 September 23. The prominence is found to remain bright and compact during the CME propagation for more than three days. We investigate the kinematic evolution of the CME substructures as the CME propagated to around 0.5 au. We find that for the first 0.28 au, both the CME front and prominence propagated coherently, indicating that the prominence was tied to the CME magnetic structure. Beyond 0.28 au, the CME bright front was seen to be distorted. However, the prominence continued to propagate at a nearly constant velocity up to at least 0.5 au. STEREO-A/HI images further show a dark ridge-like feature trailing the CME that passed over the prominence, and the prominence appeared tilted. We deduce that the prominence propagated independently of the CME at larger distances from the Sun. Overall, this study shows that both previously proposed hypotheses—namely, that the prominence is tied to or propagates independently of the CME—are valid but within different distance ranges.}, archive = {J_ApJ}, author = {Bin Zhuang and Noé Lugaz and Brian E. Wood and Carlos R. Braga and Manuela Temmer and Tingyu Gou and Phillip Hess and Shaheda Begum Shaik and Cecilia Mac Cormack and Xiaolei Li}, doi = {10.3847/1538-4357/adf2a9}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {181}, shortjournal = {The Astrophys. J.}, title = {Evolution of a coronal mass ejection with an eruptive prominence from the corona to interplanetary space}, volume = {990}, year = {2025}, }
• (2025). First detection of shock waves in RRc stars. ApJ, 990(2), 180. (www)

  @article{ , abstract = {Although shock waves have been well documented in fundamental-mode RRab stars, their existence in first-overtone pulsator stars, RRc stars, has remained uncertain. Building upon the spectroscopic frameworks established by M. Chadid et al., we present the first direct detection of multistructured shock phenomena in RRc stars. Using high-resolution phase-resolved spectroscopy, we identify unambiguous shock signatures, including H α emission, line-doubling, and large-scale variations in radial velocity and line broadening.Our analysis reveals a structured sequence of distinct shock fronts: the main outward shock, Sh He+H , the ballistic shock, Sh Ball , and a gravitational collapse shock, Sh Gravity . These phenomena produce measurable dynamical and spectroscopic effects at both photospheric and higher atmospheric layers. We find that RRc stars sustain hypersonic shock regimes despite the absence of He I or He II emission typically used in RRab classification schemes. This discrepancy is attributed to the compact and low-opacity nature of RRc atmospheres, which promotes rapid shock dissipation. These discoveries challenge conventional models of RRc atmospheres and update the classification scheme. We propose an extension to existing classification frameworks to accommodate the unique shock dynamics of RRc stars. These results challenge the long-standing assumption that first-overtone RR Lyrae pulsators lack strong shocks and demonstrate that RRc stars exhibit complex, multiphase atmospheric dynamics. Altogether, our findings reshape the current understanding of RRc atmospheric dynamics.}, archive = {J_ApJ}, author = {Junzhang Li and Merieme Chadid}, doi = {10.3847/1538-4357/adf434}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {180}, shortjournal = {The Astrophys. J.}, title = {First detection of shock waves in RRc stars}, volume = {990}, year = {2025}, }
• (2025). Circumgalactic medium cloud sizes from refractive fast radio burst scattering. ApJ, 990(2), 179. (www)

  @article{ , abstract = {We explore constraints on the size of cool gas clouds in the circumgalactic medium (CGM) obtainable from the presence, or lack thereof, of refractive scattering in fast radio bursts (FRBs). Our refractive analysis sets the most conservative bounds on parsec-scale CGM clumpiness as it does not make assumptions about the turbulent density cascade. We find that the bulk of low-redshift cool CGM gas, constrained to have densities of n e ≲ 10 −2 cm −3 , likely cannot produce two refractive images and, hence, scattering. It is only for extremely small cloud sizes ≲ 0.1 pc (about 100 times smaller than the so-called shattering scale) that such densities could result in detectable scattering. Dense n e ≳ 0.1 cm −3 gas with shattering-scale cloud sizes is more likely to inhabit the inner several kiloparsecs of the low-redshift CGM; such clouds would result in multiple refractive images and large scattering times ≳ 1−10 ms, but a small fraction of FRB sight lines are likely to be affected. We argue that such large scattering times from an intervening CGM would be a signature of subparsec clouds, even if diffractive scattering from turbulence contributes to the overall scattering. At redshift z ∼ 3, we estimate ∼0.1% of FRBs to intersect massive protoclusters, which may be the most likely place to see scattering owing to their ubiquitous n e ≈ 1 cm −3 cold gas. While much of our discussion assumes a single cloud size, we show similar results hold for a CGM cloud-size distribution motivated by hydrodynamic simulations.}, archive = {J_ApJ}, author = {Lluís Mas-Ribas and Matthew McQuinn and J. Xavier Prochaska}, doi = {10.3847/1538-4357/adf43b}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {179}, shortjournal = {The Astrophys. J.}, title = {Circumgalactic medium cloud sizes from refractive fast radio burst scattering}, volume = {990}, year = {2025}, }
• (2025). Rigidity dependence of the long-term galactic cosmic ray variation by AMS-02. ApJ, 990(2), 178. (www)

  @article{ , abstract = {Using measurements from the Alpha Magnetic Spectrometer (AMS-02) aboard the International Space Station, we have examined the long-term variations in galactic cosmic ray (GCR) proton fluxes in 2011–2018. The AMS-02 data allow for the study of time profiles and the rigidity dependence of the long-term variations observed directly in space in a wide rigidity range from 1 to 100 GV. We have investigated the rigidity dependence of the amplitude of the long-term GCR variations described by the power-law fitting over the solar cycle. For a physical interpretation, we have considered the relationship between long-term GCR variations and heliospheric magnetic field turbulence using power spectral density frequency exponents. The apparent solar cycle variability can be seen in the time profile of the spectral index γ of the power-law rigidity spectrum of long-term GCR variations for 2006–2018 during solar cycle 24. The spectral index γ shows a tendency to be higher for the solar maximum phase compared to the solar minimum phase. Furthermore, we find evidence of the energy-dependent rigidity spectrum of the long-term GCR variations observed by AMS-02. We reveal the soft rigidity spectrum of the GCR isotropic intensity variations for the solar maximum and the hard rigidity spectrum for the solar minimum owing to the essential temporal rearrangements of the structure in the heliospheric magnetic field turbulence from the maxima to minima epoch of solar activity. The long-term GCR variations by AMS-02 show the softening of the spectra toward higher energies.}, archive = {J_ApJ}, author = {R. Modzelewska and M. Siluszyk and K. Iskra and A. Gil and R. Munini and K. Marciszuk and D. Kozak-Superson}, doi = {10.3847/1538-4357/adf440}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {178}, shortjournal = {The Astrophys. J.}, title = {Rigidity dependence of the long-term galactic cosmic ray variation by AMS-02}, volume = {990}, year = {2025}, }
• (2025). The presolar heritage of 50Ti and 26Al heterogeneity in the protoplanetary disk. ApJ, 990(2), 177. (www)

  @article{ , abstract = {Nucleosynthetic isotope anomalies have been documented within the solar protoplanetary disk for several isotopes, including 48 Ca, 50 Ti, 54 Cr, 94 Mo, and 96 Zr. However, the existence of isotopic heterogeneities for short-lived radionuclides such as 26 Al remains debated. Here, we investigate potential heterogeneity in the 26 Al distribution by examining nucleosynthetic 50 Ti and 26 Al– 26 Mg isotope systematics in high-temperature early solar system solids—Ca-Al-rich inclusions (CAIs) and hibonites from CM chondrites—and comparing these with presolar grain data. We present high-precision titanium isotope measurements for 13 CAIs, comprising 11 26 Al-rich “normal”-type and two 26 Al-poor fractionation and unidentified nuclear effect (FUN)-type CAIs. Our data, combined with previously published results, reveal a fundamental decoupling between significant nucleosynthetic 50 Ti anomalies and high abundances of 26 Al, a pattern also present in presolar grains. We propose that this mutual exclusivity of 50 Ti and 26 Al observed in CAIs and CM hibonites is inherited directly from protosolar molecular cloud material. Specifically, this isotopic signature reflects the mixing of newly formed, 26 Al-rich molecular cloud material with older, Galactically inherited 26 Al-poor dust characterized by large nucleosynthetic 50 Ti variability. Consequently, solids exhibiting substantial 50 Ti anomalies ( 26 Al-poor FUN-type CAIs and CM hibonites) predominantly inherited older, 26 Al-poor presolar dust, whereas those with minimal 50 Ti anomalies and abundant 26 Al ( 26 Al-rich normal CAIs and CM hibonites) incorporated more of the younger, 26 Al-rich component. This inherited isotopic signature provides a consistent explanation for disk-scale nucleosynthetic heterogeneity in bulk meteorites, challenging the widely accepted notion that the canonical 26 Al/ 27 Al ratio of 5.25 × 10 −5 in 26 Al-rich CAIs represents the solar system average.}, archive = {J_ApJ}, author = {Kirsten K. Larsen and Troels Haugbølle and James N. Connelly and Elishevah van Kooten and Martin Bizzarro and Martin Schiller}, doi = {10.3847/1538-4357/adf4bf}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {177}, shortjournal = {The Astrophys. J.}, title = {The presolar heritage of 50Ti and 26Al heterogeneity in the protoplanetary disk}, volume = {990}, year = {2025}, }
• (2025). AGN feedback efficiency of narrow absorption line quasars. ApJ, 990(2), 176. (www)

  @article{ , abstract = {We consider if outflowing winds that are detected via narrow absorption lines (NALs) with FWHM of <500 km s −1 (i.e., NAL outflows) in quasar spectra contribute to feedback. As our sample, we choose 11 NAL systems in eight optically luminous quasars from the NAL survey of T. Misawa et al. (2007a), based on the following selection criteria: (i) they exhibit “partial coverage” suggesting quasar origin (i.e., intrinsic NALs), (ii) they have at least one low-ionization absorption line (C ii and/or Si ii ), and (iii) the Ly α absorption line is covered by available spectra. The results depend critically on this selection method, which has caveats and uncertainties associated with it, as we discuss in a dedicated section of this paper. Using the column density ratio of the excited and ground states of C ii and Si ii , we place upper limits on the electron density as n e < 0.2–18 cm −3 and lower limits on their radial distance from the flux source R as greater than several hundreds of kpc. We also calculate lower limits on the mass outflow rate and kinetic luminosity of \mathrm{log}(\dot{M}/{{M}_{\odot }\,{\rm{s}}}^{-1})\gt 1.9–5.5 and \mathrm{log}(\dot{{E}_{{\rm{k}}}}/{{\rm{erg}}\,{\rm{s}}}^{-1})\gt 42.9 –49.8, respectively. Taking the NAL selection and these results at face value, the inferred feedback efficiency can be comparable to or even larger than those of broad absorption line and other outflow classes, and large enough to generate significant active galactic nucleus feedback. However, the question of the connection of quasar-driven outflows to NAL absorbers at large distances from the central engine remains open and should be addressed by future theoretical work.}, archive = {J_ApJ}, author = {Toru Misawa and Jane C. Charlton and Michael Eracleous}, doi = {10.3847/1538-4357/adf636}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {176}, shortjournal = {The Astrophys. J.}, title = {AGN feedback efficiency of narrow absorption line quasars}, volume = {990}, year = {2025}, }
• (2025). A comprehensive study of the energy and redshift distributions of the fast radio burst population based on the first CHIME/FRB catalog. ApJ, 990(2), 175. (www)

  @article{ , abstract = {Fast radio bursts (FRBs) are brief, high-energy bursts of radio waves from extragalactic sources, and their origin remains an open question. In this paper, we perform a comprehensive analysis of the FRB population using the first CHIME/FRB catalog, focusing on their energy and redshift distributions, with careful consideration of selection effects. We investigate a range of models, including the Schechter function and the broken power-law function for the energy distribution, and several redshift evolution models, such as the star formation history (SFH) model, as well as models incorporating time delays relative to the SFH or additional redshift evolution factors. Our results indicate that the energy distribution of FRBs is best described by the Schechter function, with a power-law index of \gamma =-1.4{9}_{-0.27}^{+0.37} and a characteristic cutoff energy of {E}_{{{\rm{c}}}}=2.8{2}_{-1.47}^{+2.43}\times 1{0}^{41} erg. Furthermore, we find no evidence for redshift evolution in the energy distribution of FRBs. As for their redshift distribution, our analysis shows that it follows the cosmic SFH, without requiring additional delayed components or redshift evolution factors, suggesting that most FRBs likely originate from young stellar populations. Simultaneously, we infer a local volumetric rate of {{{\rm{\Phi }}}}_{0}=4.6{8}_{-2.39}^{+4.66}\times 1{0}^{4}\,{{{\rm{Gpc}}}}^{-3}\,{{{\rm{yr}}}}^{-1} for E > 10 39 erg. These results, robust against CHIME observational biases, may provide new insights into the underlying properties of the FRB population.}, archive = {J_ApJ}, author = {Qing-Zhen Lei and Xin-Zhe Wang and Can-Min Deng}, doi = {10.3847/1538-4357/adf646}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {175}, shortjournal = {The Astrophys. J.}, title = {A comprehensive study of the energy and redshift distributions of the fast radio burst population based on the first CHIME/FRB catalog}, volume = {990}, year = {2025}, }
• (2025). Quasar lifetime measurements from extended lyα nebulae at z ∼ 6. ApJ, 990(2), 174. (www)

  @article{ , abstract = {The existence of billion-solar-mass black holes hosted in luminous quasars within the first gigayear of cosmic history poses a challenge to our understanding of supermassive black hole (SMBH) growth. The problem is further exacerbated by the very short quasar lifetimes of t Q ≲ 10 6 yr, as derived from the extent of their proximity zone (PZ) sizes observed in the quasars’ rest-UV spectra. However, the quasar lifetime estimates based on the extents of the PZs may be underestimated, as time-variable obscuration effects might have limited the quasars’ emission along our sightline in the past. In this work, we present independent quasar lifetime measurements for six quasars at z ∼ 6 leveraging the extended nebular emission perpendicular to our line of sight. We use observations from the Very Large Telescope/Multi-Unit Spectroscopic Explorer to search for extended Ly α emission in the circumgalactic medium around quasars with small PZs and estimate their lifetimes as the light travel time between the SMBH and the outer edge of the nebula. We find agreement between the independent lifetime estimates. For one object we find a proximate absorption system prematurely truncating the extent of the quasar’s PZ, which thus results in an expected discrepancy between the lifetime estimates. Our results provide further evidence that the quasars’ current accretion episode has only recently begun, challenging our models of SMBH growth.}, archive = {J_ApJ}, author = {Dominika Ďurovčíková and Anna-Christina Eilers and Romain A. Meyer and Emanuele Paolo Farina and Eduardo Bañados and Frederick B. Davies and Joseph F. Hennawi and Chiara Mazzucchelli and Robert A. Simcoe and Fabian Walter}, doi = {10.3847/1538-4357/adf6dd}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {174}, shortjournal = {The Astrophys. J.}, title = {Quasar lifetime measurements from extended lyα nebulae at z ∼ 6}, volume = {990}, year = {2025}, }
• (2025). LZ-STAR survey: Low-metallicity star formation survey of sh2-284. i. ordered massive star formation in the outer galaxy. ApJ, 990(2), 173. (www)

  @article{ , abstract = {Star formation is a fundamental, yet poorly understood, process of the Universe. It is important to study how star formation occurs in different galactic environments. Thus, here, in the first of a series of papers, we introduce the Low-metallicity Star Formation (LZ-STAR) survey of the Sh2-284 (hereafter S284) region, which, at Z ∼  0.3–0.5 Z ⊙ , is one of the lowest-metallicity star-forming regions of our Galaxy. LZ-STAR is a multifacility survey, including observations with JWST, the Atacama Large Millimeter/submillimeter Array (ALMA), Hubble Space Telescope, Chandra, and Gemini. As a starting point, we report JWST and ALMA observations of one of the most massive protostars in the region, S284p1. The observations of shock-excited molecular hydrogen reveal a symmetric, bipolar outflow originating from the protostar, spanning several parsecs, and fully covered by the JWST field of view and ALMA observations of CO(2–1) emission. These allow us to infer that the protostar has maintained a relatively stable orientation of disk accretion over its formation history. The JWST near-infrared continuum observations detect a centrally illuminated bipolar outflow cavity around the protostar, as well as a surrounding cluster of low-mass young stars. We develop new radiative transfer models of massive protostars designed for the low metallicity of S284. Fitting these models to the protostar’s spectral energy distribution implies a current protostellar mass of ∼10 M ⊙ has formed from an initial ∼100 M ⊙ core over the last ∼3 × 10 5 yr. Overall, these results indicate that massive stars can form in an ordered manner in low-metallicity, protocluster environments.}, archive = {J_ApJ}, author = {Yu Cheng and Jonathan C. Tan and Morten Andersen and Rubén Fedriani and Yichen Zhang and Massimo Robberto and Zhi-Yun Li and Kei E. I. Tanaka}, doi = {10.3847/1538-4357/addf4b}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {173}, shortjournal = {The Astrophys. J.}, title = {LZ-STAR survey: Low-metallicity star formation survey of sh2-284. i. ordered massive star formation in the outer galaxy}, volume = {990}, year = {2025}, }
• (2025). Rapid binary mass transfer: Circumbinary outflows and angular momentum losses. ApJ, 990(2), 172. (www)

  @article{ , abstract = {High rates of stable mass transfer likely occur for some binary star systems, but the resulting flow of mass and angular momentum (AM) is unclear. We perform hydrodynamical simulations of a polytropic donor star and a point-mass secondary to determine the mass, AM, and velocity of gas that leaves the system, and the dependence on binary parameters such as mass ratio. The simulations use an adiabatic equation of state and do not include radiative cooling or irradiation of the outflow. Mass transfer is initiated by injecting heat into the stellar envelope, causing it to gradually inflate and overflow its Roche lobe. The transferred mass flows into an accretion disk, but soon begins to escape through the outer Lagrange point (L2), with a lesser amount escaping through the L3 point. This creates an equatorially concentrated circumbinary outflow with an opening angle of 10°–30° with a wind-like density profile ρ ∝ r −2 . We find that the ratios of the specific AM of the outflowing gas over that of the L2 point are approximately {0.95, 0.9, 0.8, 0.65} for mass ratios q = {0.25, 0.5, 1, 2} (accretor/donor). The asymptotic radial velocity of the outflowing gas, in units of the binary orbital velocity, is approximately 0.1–0.2 for the same mass ratios, except for q = 0.25, where it might be higher. This outflow, if ultimately unbound from the binary, may be a source of circumstellar material that interacts with ejecta from a subsequent supernova or stellar merger.}, archive = {J_ApJ}, author = {Peter Scherbak and Wenbin Lu and Jim Fuller}, doi = {10.3847/1538-4357/adf067}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {172}, shortjournal = {The Astrophys. J.}, title = {Rapid binary mass transfer: Circumbinary outflows and angular momentum losses}, volume = {990}, year = {2025}, }
• (2025). A comparative study of halo mass estimates from group catalogs and lensing signals. ApJ, 990(2), 171. (www)

  @article{ , abstract = {We compare halo mass estimates from three galaxy group catalogs (redMaPPer, Yang21, and Zou21) with those derived from gravitational lensing measurements. Each catalog employs distinct methodologies, including mass–richness relations, abundance matching, and luminosity-based calibration. A linear correlation is observed between catalog-estimated and lensing-derived masses. The redMaPPer catalog shows the best agreement, especially for lower-redshift groups, with minor deviations in higher-redshift bins. Yang21 is the only catalog containing low mass groups, which gives a reasonably good mass estimation, except for the lowest mass bin. Cross-matched groups between redMaPPer and Yang21 reveal the former catalog provides more accurate mass estimation, while the Yang21 makes underestimation of halo mass for those sharing the central galaxy with redMaPPer and overestimation of halo mass for those with different center determination with redMaPPer and for the unique Yang21 groups. These findings emphasize the importance of redshift-dependent calibration and refined group definitions for accurate mass estimation.}, archive = {J_ApJ}, author = {Xinyue Chen and Weiwei Xu and Ran Li and Huanyuan Shan and Ji Yao and Chunxiang Wang}, doi = {10.3847/1538-4357/adf332}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {171}, shortjournal = {The Astrophys. J.}, title = {A comparative study of halo mass estimates from group catalogs and lensing signals}, volume = {990}, year = {2025}, }
• (2025). On the origin of a possible hard very high energy spectrum from m87 discovered by LHAASO. ApJ, 990(2), 170. (www)

  @article{ , abstract = {Recent LHAASO observations hint at potential spectral hardening around 20 TeV in M87’s very high energy emission, suggesting a possible new radiation component. In this work, we construct averaged multiwavelength spectral energy distributions by combining data from Chandra and Swift-UVOT/XRT covering the same period as the LHAASO detection to investigate the origin of this feature. We test several radiation mechanisms, including the pp interaction, proton synchrotron emission, photomeson process, and two-zone leptonic model. We find that only the pion decay gamma rays in pp interactions can interpret this feature in the framework of the one-zone model. With analytical analysis, we prove that proton synchrotron emission cannot generate a hard spectrum above 0.17 TeV. The photomeson model requires an emission zone compressed near the Schwarzschild radius of the central supermassive black hole, incompatible with broadband optical-GeV spectral constraints. In addition, the two-zone leptonic model also emerges as a viable alternative.}, archive = {J_ApJ}, author = {Rui Xue and Jia-Chun He and Dingrong Xiong and Ze-Rui Wang}, doi = {10.3847/1538-4357/adf72c}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {170}, shortjournal = {The Astrophys. J.}, title = {On the origin of a possible hard very high energy spectrum from m87 discovered by LHAASO}, volume = {990}, year = {2025}, }
• (2025). Influence of density distribution on synchrotron polarization dispersion in magnetized interstellar medium. ApJ, 990(2), 169. (www)

  @article{ , abstract = {Faraday rotation measure (RM) synthesis is a well-known approach originated in B. J. Burn and later developed by M. A. Brentjens & A. G. de Bruyn for studying magnetic fields. This work presents a complementary approach—the polarization frequency analysis (PFA)—allowing for the properties of the turbulent magnetic field, which are difficult to include in B. J. Burn’s original approach. Based on synthetic polarization observation of magnetohydrodynamic turbulence simulation data, we study the influence of the coupling effect between density and magnetic field on synchrotron polarization dispersion. By applying the PFA to different simulated interstellar turbulence environments, we find that the PFA technique can reveal the scaling slope of the turbulent magnetic field in the case of a weak coupling effect and can also reflect the scaling slope of the RM in the case of a strong coupling effect. Since it avoids the influence of Faraday depolarization, the PFA technique is a promising way to uncover turbulence properties using observational data from the Low-Frequency Array for Radio Astronomy and the Square Kilometre Array.}, archive = {J_ApJ}, author = {Ya-Wen Xiao and Jian-Fu Zhang and Alex Lazarian and Dmitri Pogosyan}, doi = {10.3847/1538-4357/adf850}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {169}, shortjournal = {The Astrophys. J.}, title = {Influence of density distribution on synchrotron polarization dispersion in magnetized interstellar medium}, volume = {990}, year = {2025}, }
• (2025). Oxyster: A circumgalactic low-ionization oxygen nebula next to a starburst galaxy at z ∼ 1. ApJ, 990(2), 168. (www)

  @article{ , abstract = {Extended emission line nebulae around galaxies or active galactic nuclei (AGNs) provide a unique window to investigate the galactic ecosystem through the circumgalactic medium (CGM). Using Subaru Hyper Suprime-Cam narrowband imaging and spectroscopic follow-up, we serendipitously discover “Oxyster”—a large ionized nebula next to an interacting starburst galaxy at z = 0.924. The nebula is traced by extended [O ii ] λλ 3726, 3729 (∼30 kpc) and [O iii ] λ 5007 (∼20 kpc) emission lines. On the nebula luminosity–size plane, Oxyster surpasses the extended narrow-line regions around low- z AGNs, resembling a higher- z analog of “Hanny’s Voorwerp.” However, its uniformly low [O iii ]/[O ii ] ratio (O32) sets it apart from typical AGN light echoes. For the host galaxy, Hubble Space Telescope and JWST images reveal a disturbed red disk galaxy with a single blue spiral “arm.” Spectral energy distribution fitting suggests the (2–6) × 10 10 M ⊙ host galaxy sits above the star-forming main sequence with an ongoing starburst, especially in the “arm,” and has <5% luminosity contribution from AGNs, consistent with X-ray nondetection and the radio continuum. Standard photoionization and shock models struggle to explain simultaneously Oxyster’s emission line luminosities, low O32 ratio, and the nondetection of the H β line. A plausible explanation could involve the combination of a recent (<10 8 yr) starburst and a low-luminosity AGN ( L bol ∼ 1 × 10 42 erg s −1 ). While Oxyster’s nature awaits future investigation, its discovery highlights the potential of ground-based narrowband imaging to uncover extended emission line nebulae around non-AGN systems, opening new avenues for studying the CGM of normal galaxies in the early Universe.}, archive = {J_ApJ}, author = {Pengjun Lu and Mingyu Li and Dalya Baron and Minghao Yue and Song Huang and Zheng Cai}, doi = {10.3847/1538-4357/adf43a}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {168}, shortjournal = {The Astrophys. J.}, title = {Oxyster: A circumgalactic low-ionization oxygen nebula next to a starburst galaxy at z ∼ 1}, volume = {990}, year = {2025}, }
• (2025). SN 2023vbg: A type IIn supernova resembling SN 2009ip, with a long-duration precursor and early-time bump. ApJ, 990(2), 167. (www)

  @article{ , abstract = {Type IIn supernovae (SNe) resembling SN 2009ip (09ip-like SNe) originate from the interaction between circumstellar material (CSM) and the ejecta. This subclass not only shares similar observational properties around the maximum but is also commonly characterized by a long-duration precursor before its maximum. Investigating the observed properties of the precursor provides constraints on the mass-loss history of the progenitor. We present observational data of SN 2023vbg, an 09ip-like type IIn SN that displayed unique observational properties compared to other 09ip-like SNe. SN 2023vbg showed a long-duration precursor at M g ∼ −14 mag lasting for ∼100 days, followed by a bright bump at M g ∼ −17 mag at 12–25 days before the maximum. The luminosity of the precursor is similar to those of other 09ip-like SNe, but the bright bump has not been observed in other cases. After reaching the peak luminosity, the light curve exhibited a relative smooth decline. While the H α profile displays two velocity components (∼500 and 3000 km s −1 ), a broad component observed in other 09ip-like SNe was not seen, but it may emerge later. We suggest that these properties are explained by the difference in the CSM structure as compared to other 09ip-like SNe; SN 2023vbg had an inner denser CSM component, as well as generally smooth CSM density distribution in a more extended scale than in the others. Such diversity of CSM likely reflects the diversity of pre-SN outbursts, which in turn may mirror the range of evolutionary pathways in the final stages of the progenitors.}, archive = {J_ApJ}, author = {Sota Goto and Masayuki Yamanaka and Takahiro Nagayama and Keiichi Maeda and Miho Kawabata and D. K. Sahu and Avinash Singh and Anjasha Gangopadhyay and Naveen Dukiya and Kuntal Misra and Monalisa Dubey and Bhavya Ailawadhi}, doi = {10.3847/1538-4357/adf4d4}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {167}, shortjournal = {The Astrophys. J.}, title = {SN 2023vbg: A type IIn supernova resembling SN 2009ip, with a long-duration precursor and early-time bump}, volume = {990}, year = {2025}, }
• (2025). Quenching through tidal gas removal: Molecular gas and star formation in tidal tails of z ∼ 0.7 post-starburst galaxies. ApJ, 990(2), 166. (www)

  @article{ , abstract = {The active suppression of star formation in galaxies is critical for preventing the growth of overly massive systems and explaining the formation of present-day elliptical galaxies. We present a high-resolution, spatially resolved, multiwavelength study of two z ∼ 0.7 massive post-starburst galaxies, SDSS J1448+1010 and SDSS J2258+2313, from the Studying Quenching in Intermediate- z Galaxies: Gas, angu \overrightarrow{L} ar momentum, and Evolution (SQuIGG \overrightarrow{L} E) survey, providing new insights into the role of mergers in driving quenching. Atacama Large Millimeter/submillimeter Array CO(2–1) observations show that both galaxies removed ∼50% of their molecular gas into extended tidal tails, spanning up to 65 kpc, following recent mergers. Hubble Space Telescope Wide Field Camera 3 imaging and grism spectroscopy show that while SDSS J1448+1010 exhibits H α emission in its northern tidal tail consistent with ongoing star formation, SDSS J2258+2313 lacks detectable star-forming activity outside the central galaxy. Very Large Array 6 GHz continuum data reveal compact radio emission in SDSS J2258+2313, while SDSS J1448+1010 hosts small radio jets indicative of active galactic nucleus activity. Both galaxies retain substantial molecular gas reservoirs in their central regions, which appear more turbulent than “normal” star-forming galaxies, likely contributing to the observed low star formation rates in the hosts. Despite the similarities in their cold gas content and tidal features, the galaxies are distinct from each other in their star formation, gas–star alignment, and radio morphology, highlighting the complexity of tidal gas removal as a quenching mechanism at intermediate redshifts.}, archive = {J_ApJ}, author = {Vincenzo R. D’Onofrio and Justin S. Spilker and Rachel Bezanson and Robert Feldmann and Andy D. Goulding and Jenny E. Greene and Mariska Kriek and Yuanze Luo and Desika Narayanan and David J. Setton and Katherine A. Suess and Yunchong Zhang and Pengpei Zhu}, doi = {10.3847/1538-4357/adf5bd}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {166}, shortjournal = {The Astrophys. J.}, title = {Quenching through tidal gas removal: Molecular gas and star formation in tidal tails of z ∼ 0.7 post-starburst galaxies}, volume = {990}, year = {2025}, }
• (2025). Probing turbulence, gravity, supernovae, and magnetic field effects with the 6D kinematics of young stars in milky way star-forming regions. ApJ, 990(2), 165. (www)

  @article{ , abstract = {The dynamics of star-forming gas can be affected by many physical processes, such as turbulence, gravity, supernova explosions, and magnetic fields. In this paper, we investigate several nearby star-forming regions (Orion, Upper Sco, Taurus, and Perseus) for kinematic imprints of these influences on the newly formed stars. Using Gaia DR3 astrometry and APOGEE DR17 radial velocities, we compute first-order velocity structure functions (VSFs) of young stars in galactic Cartesian coordinates in both 6D (3D positions and 3D velocities) and 4D (3D positions and each 1D velocity) to identify signatures of turbulence and anisotropic motion. We also construct 3D and 1D radial velocity profiles to identify coherent expansion trends, and compare stellar proper motions to plane-of-sky magnetic field orientations in Taurus and Perseus. We find that the VSFs are mildly anisotropic, with slightly different amplitudes, slopes, or features in different directions in several groups, but in general, they are all consistent with Larson’s Relation at intermediate length scales, especially in less compact groups. In several cases, the VSFs exhibit features suggestive of local energy injection from supernovae. Radial velocity profiles reveal clear anisotropic expansion in multiple groups, with the most extreme cases corresponding to those with the most anisotropic VSFs. In Perseus, we find that the motions of young stars are preferentially perpendicular to the local magnetic field. We find multiple, overlapping causes in each group for the observed kinematics. Our findings support that young stars remember more than just the turbulent state of their natal clouds.}, archive = {J_ApJ}, author = {Benjamin N. Velguth and Yuan Li and Trung Ha and Yue Hu and Marina Kounkel and Siyao Xu and Robert Gutermuth and Hui Li and Martin D. Weinberg}, doi = {10.3847/1538-4357/adf5c0}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {165}, shortjournal = {The Astrophys. J.}, title = {Probing turbulence, gravity, supernovae, and magnetic field effects with the 6D kinematics of young stars in milky way star-forming regions}, volume = {990}, year = {2025}, }
• (2025). Pavo: Stellar feedback in action in a low-mass dwarf galaxy. ApJ, 990(2), 164. (www)

  @article{ , abstract = {MeerKAT observations of the recently discovered, extremely low mass galaxy Pavo have revealed a neutral gas (H i ) reservoir that was undetected in archival H i single dish data. We measure Pavo’s H i mass as {\mathrm{log}}\,{M}_{{\mathrm{HI}}}/{M}_{\odot }=5.79\pm 0.05 , making it the lowest mass H i reservoir currently known in an isolated galaxy (with a robust distance measurement). Despite Pavo’s extreme isolation, with no known neighbor within over 700 kpc, its H i reservoir is highly disturbed. It does not show clear signs of rotation, and its center of mass is offset from the stellar body center by 320 pc, while its peak is offset by 82 pc (both in projection). Despite this disturbed morphology, Pavo still appears to be consistent with the H i size–mass relation, although it is not possible to accurately determine a suitable inclination correction. Such disturbed, offset, and disorganized H i reservoirs are predicted by simulations of low-mass, star-forming dwarfs in which supernova-driven outflows efficiently disrupt the interstellar medium after a star formation (SF) event. It is likely that we are witnessing Pavo in precisely this period, tens to a few hundred Myr after a SF episode, when internal feedback has disrupted its gas reservoir.}, archive = {J_ApJ}, author = {Michael G. Jones and Martin P. Rey and David J. Sand and Kristine Spekkens and Burçin Mutlu-Pakdil and Elizabeth A. K. Adams and Paul Bennet and Denija Crnojević and Amandine Doliva-Dolinsky and Richard Donnerstein and Catherine E. Fielder and Julia Healy and Laura C. Hunter and Ananthan Karunakaran and Deepthi S. Prabhu and Dennis Zaritsky}, doi = {10.3847/1538-4357/adf6ab}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {164}, shortjournal = {The Astrophys. J.}, title = {Pavo: Stellar feedback in action in a low-mass dwarf galaxy}, volume = {990}, year = {2025}, }
• (2025). Formation of complex organic molecules in prestellar cores: The role of nondiffusive grain chemistry. ApJ, 990(2), 163. (www)

  @article{ , abstract = {We present the results of astrochemical modeling of complex organic molecules (COMs) in the ice and gas of the prestellar core L1544 with the recently updated MONACO rate equation-based model. The model includes, in particular, nondiffusive processes, new laboratory verified chemical routes for acetaldehyde and methane ice formation, and variations of H and H 2 desorption energies depending on the surface coverage by H 2 molecules. For the first time, we simultaneously reproduce the abundances of several oxygen-bearing COMs in the gas-phase, the approximate location of the peak of methanol emission, as well as the abundance of methanol in the icy mantles of L1544. Radical–radical reactions on the grain surface between species such as CH 3 , CH 3 O, and HCO efficiently proceed nondiffusively. COMs are delivered to the gas-phase via chemical desorption amplified by the loops of H-addition/abstraction surface reactions. However, gas-phase chemical reactions as well provide a noticeable input to the formation of COMs in the gas, but not to the COMs solid-state abundances. This particularly applies for CH 3 CHO and CH 3 OCH 3 . The simulated abundances of COMs in the ice are in the range 1%–2% (for methyl formate ice) or ∼0.1% (for CH 3 CHO and CH 3 OCH 3 ) with respect to the abundance of H 2 O ice. We stress a similarity between the simulated abundances of icy COMs in L1544 and the abundances of COMs in the gas-phase of hot cores/corinos. We compare our nondiffusive model with the diffusive model and provide constraints for the species’ diffusion-to-desorption energy ratios.}, archive = {J_ApJ}, author = {Katerina Borshcheva and Gleb Fedoseev and Anna F. Punanova and Paola Caselli and Izaskun Jiménez-Serra and Anton I. Vasyunin}, doi = {10.3847/1538-4357/adea73}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {163}, shortjournal = {The Astrophys. J.}, title = {Formation of complex organic molecules in prestellar cores: The role of nondiffusive grain chemistry}, volume = {990}, year = {2025}, }
• (2025). StreamGen: Connecting populations of streams and shells to their host galaxies. ApJ, 990(2), 162. (www)

  @article{ , abstract = {In this work, we study how the abundance and dynamics of populations of disrupting satellite galaxies change systematically as a function of host galaxy properties. We apply a theoretical model of the phase-mixing process to classify intact satellite galaxies and stellar streamlike and shell-like debris in ∼1500 Milky Way–mass systems generated by a semi-analytic galaxy formation code, SatGen . In particular, we test the effect of host galaxy halo mass, disk mass, ratio of disk scale height to length, and stellar feedback model on disrupting satellite populations. We find that the counts of tidal debris are consistent across all host galaxy models, within a given host mass range, and that all models can have streamlike debris on low-energy orbits, consistent with that observed around the Milky Way. However, we find a preference for streamlike debris on lower-energy orbits in models with a thicker (lower-density) host disk or on higher-energy orbits in models with a more massive host disk. Importantly, we observe significant halo-to-halo variance across all models. These results highlight the importance of simulating and observing large samples of Milky Way–mass galaxies and accounting for variations in host properties when using disrupting satellites in studies of near-field cosmology.}, archive = {J_ApJ}, author = {Adriana Dropulic and Nora Shipp and Stacy Kim and Zeineb Mezghanni and Lina Necib and Mariangela Lisanti}, doi = {10.3847/1538-4357/adf1a7}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {162}, shortjournal = {The Astrophys. J.}, title = {StreamGen: Connecting populations of streams and shells to their host galaxies}, volume = {990}, year = {2025}, }
• (2025). Surrogate modeling of landau damping with deep operator networks. ApJ, 990(2), 161. (www)

  @article{ , abstract = {Kinetic simulations excel at capturing microscale plasma physics phenomena with high accuracy, but their computational demands make them impractical for modeling large-scale space and astrophysical systems. In this context, we build a surrogate model, using Deep Operator Networks (DeepONets), based upon the Vlasov–Poisson simulation data to model the dynamical evolution of plasmas, focusing on the Landau damping process—a fundamental kinetic phenomenon in space and astrophysical plasmas. The trained DeepONets are able to capture the evolution of electric field energy in both linear and nonlinear regimes under various conditions. Extensive validation highlights DeepONets’ robust performance in reproducing complex plasma behaviors with high accuracy, paving the way for large-scale modeling of space and astrophysical plasmas.}, archive = {J_ApJ}, author = {Simin Shekarpaz and Chuanfei Dong and Ziyu Huang}, doi = {10.3847/1538-4357/adf3ac}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {161}, shortjournal = {The Astrophys. J.}, title = {Surrogate modeling of landau damping with deep operator networks}, volume = {990}, year = {2025}, }
• (2025). The role of population III star tidal disruption events in black hole growth at the cosmic dawn. ApJ, 990(2), 160. (www)

  @article{ , abstract = {The discovery of supermassive black holes (SMBHs) at high redshifts has intensified efforts to understand their early formation and rapid growth during the cosmic dawn. Using a semi-analytical cosmological framework, we investigate the role of tidal disruption events (TDEs) involving Population III (Pop III) stars in driving the growth of heavy-seed black holes (10 4 −10 6 M ⊙ ). Our results indicate that Pop III TDEs significantly accelerate the growth of relatively lighter massive black holes (∼10 4 −10 5 M ⊙ ), allowing them to increase their mass by roughly an order of magnitude within the first 10 Myr. Cosmological evolution modeling further supports such Pop-III-TDE-driven growth scenarios being consistent with the formation pathways of observed luminous high-redshift quasars originating from seed black holes at 10 < z < 15. We also discuss future observational probes of these early-stage growth processes that future facilities, including space-based gravitational-wave observatories and infrared telescopes like JWST, could potentially conduct. These findings provide a clear observational framework to test the critical role of Pop III star interactions in the rapid buildup of SMBHs during the earliest epochs.}, archive = {J_ApJ}, author = {Zijian Wang and Yiqiu Ma and Yuxuan Li and Zheng Cai and Chanyan Wang and Qingwen Wu}, doi = {10.3847/1538-4357/adf435}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {160}, shortjournal = {The Astrophys. J.}, title = {The role of population III star tidal disruption events in black hole growth at the cosmic dawn}, volume = {990}, year = {2025}, }
• (2025). Spectral energy correlations of gamma-ray bursts from structured jets. ApJ, 990(2), 159. (www)

  @article{ , abstract = {Using 148 out-axis gamma-ray bursts (GRBs), we build their spectrum–energy relations of peak energy versus isotropic energy, peak energy versus peak luminosity, and peak energy versus jet-calibrated energy, which are corrected for a structured jet model. These relations are found to depend on the observer’s viewing angle as long as the observer is within the jet cone. After converting the out-axis energy relations to the in-axis situations, we find that the corresponding in-axis energy relations are universally steeper, of which all of them can be roughly interpreted by the synchrotron radiation mechanism as shown in Xu et al. Meanwhile, we notice that the in-axis means of isotropic energies are about 1 order of magnitude larger than the out-axis means for both short and long bursts except the supernova-associated GRBs. Furthermore, we apply all the newly found energy relations to construct the Hubble diagrams of out/in-axis bursts. It is found that the in-axis Hubble diagrams are better cosmological indicators.}, archive = {J_ApJ}, author = {X. L. Zhang and Z. B. Zhang and Y. F. Huang and D. Li and X. J. Li and L. M. Song}, doi = {10.3847/1538-4357/adf5bf}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {159}, shortjournal = {The Astrophys. J.}, title = {Spectral energy correlations of gamma-ray bursts from structured jets}, volume = {990}, year = {2025}, }
• (2025). Optical emission from luminous and very soft X-ray sources in nearby galaxies: Testing the scenario of edge-on supercritical accretion systems. ApJ, 990(2), 158. (www)

  @article{ , abstract = {Supercritical accretion onto compact objects is expected to drive optically thick winds, resulting in observed X-ray emission as a function of viewing angle. However, their optical emission, either from the outer accretion disk or companion surface, tends to be nearly isotropic. Based on a sample of luminous and very soft X-ray sources that are argued to be supercritical accretion systems viewed close to edge-on, we identify the optical counterparts for some of them and compare the optical properties with those of ultraluminous X-ray sources, which are supposed to be supercritical accretion systems viewed close to face-on. The optical luminosity is found in a wide range, with the absolute visual magnitude ranging from dimmer than −1.2 in some sources to about −7 in one case. Most sources show a power-law-like spectrum, while four of them display a blackbody shape. One of them shows an optical spectrum resembling a B-type main sequence, suggesting that it may be a Be white dwarf system. Strong variability in flux at timescales as short as 10 days are revealed, indicating that some of these sources are powered by accretion onto compact objects. These suggest that the luminous and very soft X-ray sources in nearby galaxies have a diverse population, and some of them are indeed consistent with emission from supercritical accretion, with consistent optical magnitudes and colors. Future optical spectroscopic observations are needed to further constrain their natures.}, archive = {J_ApJ}, author = {Xiaohong Tang and Hua Feng}, doi = {10.3847/1538-4357/adf7a8}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {158}, shortjournal = {The Astrophys. J.}, title = {Optical emission from luminous and very soft X-ray sources in nearby galaxies: Testing the scenario of edge-on supercritical accretion systems}, volume = {990}, year = {2025}, }
• (2025). Shear particle acceleration in structured gamma-ray burst jets. III. the radiation physics of bright prompt optical flash. ApJ, 990(2), 157. (www)

  @article{ , abstract = {The radiation physics of bright prompt optical emission of gamma-ray bursts (GRBs) remains a puzzle. Assuming that the GRB ejecta is structured, we investigated this issue by characterizing the ejecta as an ultrarelativistic uniform jet core surrounded by a mild-relativistic cocoon. The mixed jet-cocoon (MJC) region can accelerate particles through the shear acceleration mechanism. Parameterizing the radial velocity profile of the MJC region with an exponential function and assuming a uniform magnetic field configuration, we show that the synchrotron radiation of the shear-accelerated electrons can produce a bright optical flash. Emission of the self-synchrotron Compton process of the electron population can result in an X-ray excess and an extra MeV–GeV gamma-ray flash relative to the Band function component in the keV–MeV band, which is attributed to the synchrotron radiation of the shock-accelerated electrons in the jet core. Our model reasonably represents the extremely bright optical flash and spectral characteristics of GRBs 990123, 080319B, and 130427A. The inferred magnetic field strength of the MJC region is above 10 5 G, potentially suggesting that the jets of these GRBs are highly magnetized.}, archive = {J_ApJ}, author = {Zi-Qi Wang and Xiao-Li Huang and En-Wei Liang}, doi = {10.3847/1538-4357/adfa1b}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {157}, shortjournal = {The Astrophys. J.}, title = {Shear particle acceleration in structured gamma-ray burst jets. III. the radiation physics of bright prompt optical flash}, volume = {990}, year = {2025}, }
• (2025). Theoretical radio signals from radio-band gravitational waves converted from the neutron star magnetic field. ApJ, 990(2), 156. (www)

  @article{ , abstract = {Gravitational waves (GWs) can convert into electromagnetic waves in the presence of a magnetic field via the Gertsenshtein–Zeldovich effect. The characteristics of the magnetic field substantially affect this conversion probability. This paper confirms that strong magnetic fields in neutron stars significantly enhance the conversion probability, facilitating detectable radio signatures of very high-frequency (VHF, \left(1{0}^{6}\,\unicode{x02013}\,1{0}^{11}\,{\rm{Hz}}\right) ) GWs. We theoretically identify two distinct signatures using single-dish telescopes (FAST, TMRT, QTT, GBT) and interferometers (SKA1/2-MID): transient signals from burst-like GW sources and persistent signals from cosmological background GW sources. These signatures are mapped to graviton spectral lines derived from quantum field theory by incorporating spin-2 and mass constraints, resulting in smooth, featureless profiles that are critical for distinguishing GW signals from astrophysical foregrounds. FAST attains a characteristic strain bound of h c < 10 −23 , approaching 10 −24 in the frequency range of 1–3 GHz with a 6 hr observation period. This performance exceeds the 5 σ detection thresholds for GWs originating from primordial black holes and nears the limits set by Big Bang nucleosynthesis. Additionally, projections for SKA2-MID indicate even greater sensitivity. Detecting such GWs would improve our comprehension of cosmological models, refine the parameter spaces for primordial black holes, and function as a test for quantum field theory. This approach addresses significant deficiencies in VHF GW research, improving detection sensitivity and facilitating the advancement of next-generation radio telescopes such as FASTA and Square Kilometre Array, which feature larger fields of view and enhanced gain.}, archive = {J_ApJ}, author = {Wei Hong and Zhen-Zhao Tao and Peng He and Tong-Jie Zhang}, doi = {10.3847/1538-4357/adf19a}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {156}, shortjournal = {The Astrophys. J.}, title = {Theoretical radio signals from radio-band gravitational waves converted from the neutron star magnetic field}, volume = {990}, year = {2025}, }
• (2025). Unraveling the feedback-regulated star formation activities around the expanding galactic mid-infrared bubble [HKS2019] e71. ApJ, 990(2), 155. (www)

  @article{ , abstract = {We explore the physical environment of the Galactic mid-infrared (MIR) bubble [HKS2019] E71 (hereafter E71) through a multiwavelength approach. E71 is located at the edge of a filamentary structure, as traced in Herschel images (250–500 μ m), Herschel column density map, and molecular maps in the velocity range [−20, −14] km s −1 . It hosts a stellar cluster (radius ∼ 1.26 pc, distance ∼1.81 ± 0.15 kpc) associated with radio continuum emission, including a centrally positioned B1.5-type massive star (hereafter “m2”), along with an enhanced population of evolved low-mass stars and young stellar objects. MIR images and molecular line maps reveal a photodissociation region surrounding “m2,” exhibiting an arc-like structure along the edges of E71. Regularly spaced molecular and dust condensations are identified along this structure. The position–velocity map of 12 CO (1–0) emission suggests an expansion of molecular gas concentrated at the periphery of E71. Near-infrared spectroscopic observations with TANSPEC confirm the presence of the accretion process in a massive young stellar object (MYSO) located near the edge of the bubble. High-resolution uGMRT radio continuum maps uncover substructures in the ionized emission, both toward the MYSO and the center of E71. These findings support that “m2” has shaped an arc-like morphology through its feedback processes. The pressure exerted by “m2” and the velocity structure of the 12/13 CO (1–0) emission suggest that the stellar feedback has likely driven out molecular material, leading to the formation of the expanding E71 bubble. Our overall investigation infers that the “collect and collapse” process might be a possible mechanism that can describe the ongoing star formation activities around the E71 bubble.}, archive = {J_ApJ}, author = {Aayushi Verma and Saurabh Sharma and Lokesh K. Dewangan and Tarak Chand and Ariful Hoque and Devendra K. Ojha and Harmeen Kaur and Ram Kesh Yadav and Mamta and Manojit Chakraborty and Archana Gupta}, doi = {10.3847/1538-4357/adf21d}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {155}, shortjournal = {The Astrophys. J.}, title = {Unraveling the feedback-regulated star formation activities around the expanding galactic mid-infrared bubble [HKS2019] e71}, volume = {990}, year = {2025}, }
• (2025). Tracing the light: Identification for the optical counterpart candidates of binary black holes during o3. ApJ, 990(2), 154. (www)

  @article{ , abstract = {The accretion disks of active galactic nuclei (AGN) are widely considered the ideal environments for binary black hole mergers and the only plausible sites for their electromagnetic counterparts. M. J. Graham et al. (2023) identified seven AGN flares that are potentially associated with gravitational wave (GW) events detected by the LIGO–Virgo–KAGRA Collaboration during the third observing run. In this article, utilizing an additional three years of Zwicky Transient Facility public data after their discovery, we conduct an updated analysis and find that only three flares can be identified. By implementing a joint analysis of optical and GW data through a Bayesian framework, we find two flares exhibit a strong correlation with GW events, with no secondary flares observed in their host AGN up to 2024 October 31. Combining these two most robust associations, we derive a Hubble constant measurement of {H}_{0}=72.{1}_{-23.1}^{+23.9}\,\mathrm{km}\,{{\rm{s}}}^{-1}\,{\mathrm{Mpc}}^{-1} and incorporating the multimessenger event GW170817 improves the precision to {H}_{0}=73.{5}_{-6.9}^{+9.8}\,{\rm{km}}\,{{\rm{s}}}^{-1}{{\rm{Mpc}}}^{-1} . Both results are consistent with existing measurements reported in the literature.}, archive = {J_ApJ}, author = {Lei He and Zhengyan Liu and Rui Niu and Bingzhou Gao and Mingshen Zhou and Purun Zou and Runduo Liang and Wen Zhao and Ning Jiang and Zhen-Yi Cai and Zi-Gao Dai and Ye-Fei Yuan}, doi = {10.3847/1538-4357/adf284}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {154}, shortjournal = {The Astrophys. J.}, title = {Tracing the light: Identification for the optical counterpart candidates of binary black holes during o3}, volume = {990}, year = {2025}, }
• (2025). A time-domain study of repeat and nonrepeat fast radio bursts. ApJ, 990(2), 153. (www)

  @article{ , abstract = {Fast radio bursts (FRBs) are extremely energetic radio transients, typically classified as repeat or nonrepeat, but their origins remain uncertain. In this work, we focus on the timing characteristics of the pulses in 536 FRBs observed by CHIME with improved pulse-finding and fitting algorithms. The results show that the fitted mean of rise time, decay time, FWHM, and minimum variable timescale distributions for the repeat FRBs are larger. Furthermore, the Kolmogorov–Smirnov test reveals significant differences (>5 σ ) for some parameters between repeat and nonrepeat FRBs, implying that the former may have more stable and longer-lived sources (e.g., magnetars). However, we do not find significant differences in waiting times, which may be a limitation of the sample. We also investigate the relationship between these parameters, identifying some correlations, e.g., a negative power-law correlation between pulse amplitude and FWHM. Our findings suggest that the repeat and nonrepeat FRBs originate from different progenitors, environments, and/or emission mechanisms. Interestingly, both of their observations do not contradict that they originate from within the magnetosphere of a magnetar.}, archive = {J_ApJ}, author = {Zheng-Huo Jiang and Shuo Xiao and Pei Wang and Jiao-Jiao Yang and Tong-Lei Liao and Zi-Yi You and Di Li}, doi = {10.3847/1538-4357/adf4c7}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {153}, shortjournal = {The Astrophys. J.}, title = {A time-domain study of repeat and nonrepeat fast radio bursts}, volume = {990}, year = {2025}, }
• (2025). Massive extremely high-velocity outflow in the quasar j164653.72+243942.2. ApJ, 990(2), 152. (www)

  @article{ , abstract = {We present analysis of one of the most extreme quasar outflows found to date in our survey of extremely high-velocity outflows (EHVOs). J164653.72+243942.2 ( z em ∼ 3.04) shows variable C iv λλ 1548,1551 absorption at speeds larger than 0.1 c , accompanied by Si iv , N v, and Ly α , and disappearing absorption at lower speeds. We perform absorption measurements using the apparent optical depth method and SimBAL. We find the absorption to be very broad (Δ v ∼  35,100 km s −1 in the first epoch and 13,000 km s −1 in the second one) and fast ( v max ∼  –50,200 km s −1 and −49,000 km s −1 , respectively). We measure large column densities ( {\mathrm{log}}\,{N}_{{\rm{H}}}\,\gt 21.6 (cm −2 )) and are able to place distance estimates for the EHVO (5 ≲ R ≲ 28 pc) and the lower-velocity outflow (7 ≲ R ≲ 540 pc). We estimate a mass outflow rate for the EHVO to be {\dot{M}}_{\mathrm{out}}\sim 50\mbox{--}290\,{M}_{\odot }\,{\mathrm{yr}}^{-1} and a kinetic luminosity of {\mathrm{log}}\,\,{L}_{\mathrm{KE}}\sim 46.5\mbox{--}47.2\,(\mathrm{erg}\,{{\rm{s}}}^{-1}) in both epochs. The lower-velocity component has a mass outflow rate {\dot{M}}_{\mathrm{out}}\sim 10\mbox{--}790\,{M}_{\odot }\,{\mathrm{yr}}^{-1} and a kinetic luminosity of {\mathrm{log}}\,\,{L}_{\mathrm{KE}}\sim 45.3\mbox{--}47.2\,(\mathrm{erg}\,{{\rm{s}}}^{-1}) . We find that J164653.72+243942.2 is not an outlier among EHVO quasars in regard to its physical properties. While its column density is lower than typical BAL values, its higher outflow velocities drive most of the mass outflow rate and kinetic luminosity. These results emphasize the crucial role of EHVOs in powering quasar feedback, and failing to account for these outflows likely leads to underestimating the feedback impact on galaxies.}, archive = {J_ApJ}, author = {Paola Rodríguez Hidalgo and Hyunseop Choi and Patrick B. Hall and Karen M. Leighly and Liliana Flores and Mikel M. Charles and Cora DeFrancesco and Julie Hlavacek-Larrondo and Laurence Perreault-Levasseur}, doi = {10.3847/1538-4357/adef0d}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {152}, shortjournal = {The Astrophys. J.}, title = {Massive extremely high-velocity outflow in the quasar j164653.72+243942.2}, volume = {990}, year = {2025}, }
• (2025). The cosmic evolution of c IV absorbers at 1.4 < z < 4.5: Insights from 100,000 systems in DESI quasars. ApJ, 990(2), 151. (www)

  @article{ , abstract = {We present the largest catalog to date of triply ionized carbon (C iv ) absorbers detected in quasar spectra from the Dark Energy Spectroscopic Instrument. Using an automated matched-kernel convolution method with adaptive signal-to-noise thresholds, we identify 101,487 C iv systems in the redshift range 1.4 < z < 4.5 from 300,637 quasar spectra. Completeness is estimated via Monte Carlo simulations, and the catalog is 50% complete at EW C IV ≥ 0.4 Å. The differential equivalent width frequency distribution declines exponentially and shows weak redshift evolution. The absorber incidence per unit comoving path increases by a factor of 2–5 from z ≈ 4.5 to z ≈ 1.4, with stronger redshift evolution for strong systems. Using column densities derived from the apparent optical depth method, we constrain the cosmic mass density of C iv , Ω C IV , which increases by a factor of ∼3.8 from (0.82 ± 0.05) × 10 −8 at z ≈ 4.5 to (3.16 ± 0.2) × 10 −8 at z ≈ 1.4. From Ω C IV , we estimate a lower limit on intergalactic medium metallicity {\mathrm{log}}({Z}_{{\rm{IGM}}}/{Z}_{\odot })\gtrsim -3.25 at z ∼ 2.3, with a smooth decline at higher redshifts. These trends trace the cosmic star formation history and He ii photoheating rate, suggesting a link between C iv enrichment, star formation, and UV background over ∼3 Gyr. The catalog also provides a critical resource for future studies connecting circumgalactic metals to galaxy evolution, especially near cosmic noon.}, archive = {J_ApJ}, author = {Abhijeet Anand and J. Aguilar and S. Ahlen and D. Bianchi and A. Brodzeller and D. Brooks and R. Canning and T. Claybaugh and A. Cuceu and A. de la Macorra and P. Doel and S. Ferraro and A. Font-Ribera and J. E. Forero-Romero and E. Gaztañaga and S. Gontcho A Gontcho and G. Gutierrez and J. Guy and H. K. Herrera-Alcantar and M. Ishak and S. Juneau and R. Kehoe and A. Kremin and M. Landriau and L. Le Guillou and M. E. Levi and M. Manera and A. Meisner and R. Miquel and J. Moustakas and A. Muñoz-Gutiérrez and L. Napolitano and I. Pérez-Ràfols and G. Rossi and E. Sanchez and D. Schlegel and M. Schubnell and D. Sprayberry and G. Tarlé and M. J. Temple and B. A. Weaver and R. Zhou}, doi = {10.3847/1538-4357/adef3c}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {151}, shortjournal = {The Astrophys. J.}, title = {The cosmic evolution of c IV absorbers at 1.4 < z < 4.5: Insights from 100,000 systems in DESI quasars}, volume = {990}, year = {2025}, }
• (2025). PEACHES. IV. tracing the formation and evolution of C2H in perseus low-mass protostars. ApJ, 990(2), 150. (www)

  @article{ , abstract = {The radical hydrocarbon molecule C 2 H is widely detected in various stages of star and planet formation, and has emerged as a useful tracer of high-C/O gas within the photochemically active surface layers of mature (Class II) protoplanetary disks. However, the chemistry and evolution of C 2 H within younger (Class 0/I) protostars remains much more poorly understood. Here, using data observed as part of the PEACHES survey along with new Atacama Large Millimeter/submillimeter Array Atacama Compact Array observations, we investigate the C 2 H emission toward an unbiased sample of 35 Class 0/I low-mass protostars in Perseus. With this large sample, we identify a clear association between C 2 H emission and the protostellar outflow cavity walls, and a consistent spatial anticorrelation between C 2 H and SO emission. Together, these trends confirm that C 2 H is tracing photochemically active, O-poor gas in these younger sources. We fitted the C 2 H spectra with a simple LTE model to yield column density maps, and find values ranging from 10 14 to 10 15 cm −2 in these sources. We also looked for trends in the C 2 H emission morphology as a function of various protostellar evolutionary metrics, but find no clear patterns; the C 2 H emission remains spatially extended in most sources, independent of age. This indicates that the transition to the compact C 2 H emission observed on the surfaces of Class II disks must happen rapidly, sometime just after the embedded stage.}, archive = {J_ApJ}, author = {Jack G. Anderson and Jennifer B. Bergner and Yao-Lun Yang and Yichen Zhang and Nami Sakai}, doi = {10.3847/1538-4357/adf199}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {150}, shortjournal = {The Astrophys. J.}, title = {PEACHES. IV. tracing the formation and evolution of C2H in perseus low-mass protostars}, volume = {990}, year = {2025}, }
• (2025). JWST discovery of a high-redshift tidal disruption event candidate in COSMOS-web. ApJ, 990(2), 149. (www)

  @article{ , abstract = {The rates and properties of tidal disruption events (TDEs) provide valuable insights into their host galaxy central stellar densities and the demographics of their central supermassive black holes. TDEs have been observed only at low redshifts ( z ≲ 1), due to the difficulty in conducting deep time-domain surveys. In this work, we present the discovery of a high-redshift TDE candidate, HZTDE-1, in the COSMOS-Web survey with JWST’s NIRCam, using a novel selection technique based on color and morphology. We outline a methodology for identifying high- z TDEs in deep infrared imaging surveys, leveraging the unique spectral energy distributions and morphologies of these transients. While focused on TDEs, this methodology could also be applied to find other UV-bright transients, such as superluminous supernovae (SLSNe). We apply this technique to COSMOS-Web in filters F115W, F150W, F277W, and F444W, and identify HZTDE-1, a transient point source relative to archival UltraVISTA infrared observations. If we assume it is a TDE, we estimate a photometric redshift of z\,=\,5.0{2}_{-1.11}^{+1.32} . HZTDE-1 cannot be explained by reasonable supernova or active galactic nuclei models. However, an SLSN at z ≳ 3 can also plausibly explain this transient and would be the highest-redshift SLSN yet known. If confirmed with follow-up observations, HZTDE-1 would represent the highest-redshift TDE discovery to date, and suggest an enhancement of the TDE rate in the high-redshift Universe. Our method, which can be applied to future deep surveys with the JWST and Nancy Grace Roman Space Telescope, offers a pathway to identify TDEs at z > 4 and probe black hole demographics at early cosmic times.}, archive = {J_ApJ}, author = {Mitchell Karmen and Suvi Gezari and Erini Lambrides and Hollis B. Akins and Colin Norman and Caitlin M. Casey and Justin Pierel and David Coulter and Armin Rest and Ori Dr. Fox and Yukta Ajay and Natalie Allen and Nicole E. Drakos and Seiji Fujimoto and Sebastian Gomez and Ghassem Gozaliasl and Olivier Ilbert and Jeyhan S. Kartaltepe and Anton M. Koekemoer and Zachary G. Lane and Henry Joy McCracken and Louise Paquereau and Jason Rhodes and Brant E. Robertson and Marko Shuntov and Matthew R. Siebert and Sune Toft and Thomas Wevers and Yossef Zenati}, doi = {10.3847/1538-4357/adf216}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {149}, shortjournal = {The Astrophys. J.}, title = {JWST discovery of a high-redshift tidal disruption event candidate in COSMOS-web}, volume = {990}, year = {2025}, }
• (2025). One year of SN 2023ixf: Breaking through the degenerate parameter space in light-curve models with pulsating progenitors. ApJ, 990(2), 148. (www)

  @article{ , abstract = {We present and analyze the extensive optical broadband photometry of the Type II SN 2023ixf up to 1 yr after explosion. We find that, when compared to two preexisting model grids, the bolometric light curve is consistent with drastically different combinations of progenitor and explosion properties. This may be an effect of known degeneracies in Type IIP light-curve models. We independently compute a large grid of MESA+STELLA single-star progenitor and light-curve models with various zero-age main-sequence masses, mass-loss efficiencies, and convective efficiencies. Using the observed progenitor variability as an additional constraint, we select stellar models consistent with the pulsation period and explode them according to previously established scaling laws to match plateau properties. Our hydrodynamic modeling indicates that SN 2023ixf is most consistent with a moderate-energy ( {E}_{{\rm{\exp }}}\approx 7\times 1{0}^{50} erg) explosion of an initially high-mass red supergiant progenitor (≳16.5 M ⊙ ) that lost a significant amount of mass in its prior evolution, leaving a low-mass hydrogen envelope (≲3 M ⊙ ) at the time of explosion, with a radius ≳950 R ⊙ and a synthesized 56 Ni mass of ≈0.068 M ⊙ . We posit that previous mass transfer in a binary system may have stripped the envelope of SN 2023ixf’s progenitor. The analysis method with pulsation period presented in this work offers a way to break degeneracies in light-curve modeling in the future, particularly with the upcoming Vera C. Rubin Observatory Legacy Survey of Space and Time, when a record of progenitor variability will be more common.}, archive = {J_ApJ}, author = {Brian Hsu and Nathan Smith and Jared A. Goldberg and K. Azalee Bostroem and Griffin Hosseinzadeh and David J. Sand and Jeniveve Pearson and Daichi Hiramatsu and Jennifer E. Andrews and Emma R. Beasor and Yize Dong and Joseph Farah and Lluís Galbany and Sebastian Gomez and Estefania Padilla Gonzalez and Claudia P. Gutiérrez and D. Andrew Howell and Réka Könyves-Tóth and Curtis McCully and Megan Newsome and Manisha Shrestha and Giacomo Terreran and V. Ashley Villar and Xiaofeng Wang}, doi = {10.3847/1538-4357/adf222}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {148}, shortjournal = {The Astrophys. J.}, title = {One year of SN 2023ixf: Breaking through the degenerate parameter space in light-curve models with pulsating progenitors}, volume = {990}, year = {2025}, }
• (2025). Structure and skewness of the effective inspiral spin distribution of binary black hole mergers. ApJ, 990(2), 147. (www)

  @article{ , abstract = {The detection of gravitational waves has brought to light a population of binary black holes that merge within a Hubble time. Multiple formation channels can contribute to this population, making it difficult to definitively associate particular population features with underlying stellar physics. Black hole spins are considered an important discriminator between various channels, but they are less well measured than masses, making conclusive astrophysical statements using spins difficult thus far. In this paper, we consider the distribution of the effective inspiral spin χ eff —a quantity much better measured than individual component spins. We show that non-Gaussian features like skewness, asymmetry about zero, and multimodality can naturally arise in the χ eff distribution when multiple channels contribute to the population. Searching for such features, we find signs of skewness and asymmetry already in the current catalogs, but no statistically significant signs of bimodality. These features provide robust evidence for the presence of a subpopulation with spins preferentially aligned to the binary’s orbital angular momentum; and we conservatively estimate the fraction of this subpopulation to be at least 12%–17% (at 90% credibility). Our models do not find a sharp excess of nonspinning systems and instead find that at least ∼20% of the binaries have some degree of negative χ eff . The data also suggest that, if preferentially aligned mergers form a significant fraction of the population, they must have small spins.}, archive = {J_ApJ}, author = {Sharan Banagiri and Thomas A. Callister and Christian Adamcewicz and Zoheyr Doctor and Vicky Kalogera}, doi = {10.3847/1538-4357/adf4c6}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {147}, shortjournal = {The Astrophys. J.}, title = {Structure and skewness of the effective inspiral spin distribution of binary black hole mergers}, volume = {990}, year = {2025}, }
• (2025). Transient LoBALs at high velocities: A case of extreme broad absorption line variability in j115636.82+085628.9*. ApJ, 990(2), 146. (www)

  @article{ , abstract = {We present a multiepoch spectroscopic study of the broad absorption line (BAL) quasar J115636.82+085628.9 ( z em = 2.1077), based on five spectra spanning nearly two decades in the observer’s frame. This source exhibits remarkable variability in both low-ionization (LoBAL: Al iii and Mg ii ) and high-ionization (HiBAL: C iv and Si iv ) absorption features. For the first time, we detect the emergence and subsequent disappearance of LoBAL troughs at high velocities (∼20,000 km s −1 ), coinciding with the strengthening and weakening of the corresponding HiBAL absorption. The C iv BAL profile extends from ∼6700 km s −1 to a conservative upper limit of 30,000 km s −1 and is composed of narrow, variable absorption features embedded within a broad, smooth envelope. Both C iv and Si iv BAL troughs exhibit dramatic equivalent width (EW) changes—among the most extreme reported to date. Notably, these EW variations are strongly anticorrelated with continuum flux changes inferred from optical photometric light curves. We interpret this variability as the result of a new absorbing flow transiting into our line of sight, increasing the shielding of a more distant, preexisting outflow and giving rise to transient LoBAL absorption. This scenario supports a unified picture in which LoBAL and HiBAL features arise from similar outflow structures, with observed differences governed primarily by line-of-sight column densities consistent with previous findings.}, archive = {J_ApJ}, author = {P. Aromal and R. Srianand and S. C. Gallagher and M. Vivek and P. Petitjean}, doi = {10.3847/1538-4357/adf4de}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {146}, shortjournal = {The Astrophys. J.}, title = {Transient LoBALs at high velocities: A case of extreme broad absorption line variability in j115636.82+085628.9*}, volume = {990}, year = {2025}, }
• (2025). ALMA reveals an eccentricity gradient in the fomalhaut debris disk. ApJ, 990(2), 145. (www)

  @article{ , abstract = {We present evidence of a negative eccentricity gradient in the debris disk of the nearby A-type main-sequence star, Fomalhaut. Fitting to the high-resolution, archival ALMA 1.32 mm continuum data for Fomalhaut (with a synthesized angular resolution of 0 \mathop{.}\limits^{\unicode{x02033}} 76 × 0 \mathop{.}\limits^{\unicode{x02033}} 55; 4–6 au), we present a model that describes the bulk properties of the disk (semimajor axis, width, and geometry) and its asymmetric morphology. The best-fit model incorporates a forced eccentricity gradient that varies with semimajor axis, {e}_{f}\propto {a}^{{n}_{{{\rm{pow}}}}} , a generalized form of the parametric models of E. M. Lynch & J. B. Lovell, with n pow = −1.75 ± 0.16. We show that this model is statistically preferred to models with constant forced and free eccentricities. In comparison to disk models with constant forced eccentricities, negative eccentricity gradient models broaden disk widths at pericenter versus apocenter, and increase disk surface densities at apocenter versus pericenter, both of which are seen in the Fomalhaut disk, and which we collectively term “Eccentric Velocity Divergence.” We propose single-planet architectures consistent with the model and investigate the stability of the disk over 440 Myr to planet–disk interactions via N -body modeling. We find that Fomalhaut’s ring eccentricity plausibly formed during the protoplanetary disk stage, with subsequent planet–disk interactions responsible for carving the disk morphology.}, archive = {J_ApJ}, author = {Joshua B. Lovell and Elliot M. Lynch and Jay Chittidi and Antranik A. Sefilian and Sean M. Andrews and Grant M. Kennedy and Meredith MacGregor and David J. Wilner and Mark C. Wyatt}, doi = {10.3847/1538-4357/adfadc}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {145}, shortjournal = {The Astrophys. J.}, title = {ALMA reveals an eccentricity gradient in the fomalhaut debris disk}, volume = {990}, year = {2025}, }
• (2025). Multiscale periodic variations of solar active regions during the time interval 1996–2023. ApJ, 990(2), 144. (www)

  @article{ , abstract = {Solar active regions are believed to provide significant information on the mutual conversion of the poloidal and toroidal components of the global magnetic field. However, the multiscale periodic variations, in particular the quasi-biennial oscillations (QBOs), of solar active regions are not fully understood. In the present study, the flux, area, and number of solar active regions, as well as the sunspot number data in the period from 1996 May to 2023 November, are studied in detail. The multiscale periodic components in the above four data sets are investigated by the techniques of ensemble empirical mode decomposition and cross-correlation analysis. The main results are as follows. (1) The four data sets exhibit similar periodic components, including the 11 yr Schwabe cycle, the QBOs, and a Rieger-type period. (2) The multiscale periodicity of solar active regions shows different physical characteristics. Under different periodic scales, the highest correlation is between active region flux and area, indicating that active region flux and area better reflect the evolution of active regions. (3) By superimposing the QBOs on the 11 yr Schwabe cycle, the Gnevyshev gap phenomenon was clearly observed, implying that the Gnevyshev gap may be caused by the modulation of the 11 yr Schwabe cycle. (4) The active region flux in both hemispheres shows similar periodic components to the full disk, but the periodic variations are uneven between the northern and southern hemispheres. The results of our analysis could be beneficial for the understanding of the spatiotemporal distribution of solar active regions, and could also provide statistical constraints on solar dynamo theories.}, archive = {J_ApJ}, author = {Shangxi Li and Tingting Xu and Miao Wan and Linhua Deng and Xinhua Zhao and Shiyang Qi and Nanbin Xiang and Wenrong Li and Weihong Zhou}, doi = {10.3847/1538-4357/adf2ab}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {144}, shortjournal = {The Astrophys. J.}, title = {Multiscale periodic variations of solar active regions during the time interval 1996–2023}, volume = {990}, year = {2025}, }
• (2025). Kinetic simulations of the cosmic-ray pressure anisotropy instability: Cosmic-ray scattering rate in the saturated state. ApJ, 990(2), 143. (www)

  @article{ , abstract = {Cosmic-ray (CR) feedback plays a vital role in shaping the formation and evolution of galaxies through their interaction with magnetohydrodynamic waves. In the CR self-confinement scenario, the waves are generated by the CR gyroresonant instabilities via CR streaming or CR pressure anisotropy and saturate by balancing wave damping. The resulting effective particle scattering rate by the waves, ν eff , critically sets the coupling between the CRs and background gas, but the efficiency of CR feedback is yet poorly constrained. We employ 1D kinetic simulations under the magnetohydrodynamic-particle-in-cell framework with the adaptive δ f method to quantify ν eff for the saturated state of the CR pressure anisotropy instability with ion-neutral friction. We drive CR pressure anisotropy by expanding/compressing the box, mimicking the background evolution of magnetic field strength, and the CR pressure anisotropy eventually reaches a quasi-steady state by balancing quasi-linear diffusion. At the saturated state, we measure ν eff and the CR pressure anisotropy level, establishing a calibrated scaling relation with environmental parameters. The scaling relation is consistent with quasi-linear theory and can be incorporated to CR fluid models, in either the single-fluid or p -by- p treatments. Our results serve as a basis for accurately calibrating the subgrid physics in macroscopic studies of CR feedback and transport.}, archive = {J_ApJ}, author = {Xiaochen Sun and Xue-Ning Bai and Xihui Zhao}, doi = {10.3847/1538-4357/adf334}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {143}, shortjournal = {The Astrophys. J.}, title = {Kinetic simulations of the cosmic-ray pressure anisotropy instability: Cosmic-ray scattering rate in the saturated state}, volume = {990}, year = {2025}, }
• (2025). Possible neutrino emission from the pulsar wind nebula g63.7+1.1. ApJ, 990(2), 142. (www)

  @article{ , abstract = {We report on our finding of an excess of 5{4}_{-15}^{+16} neutrinos at the location of the pulsar wind nebula (PWN) G63.7+1.1. By analyzing the IceCube track-like neutrino data for a group of 14 PWNe, which are selected as targets because of their reported association with molecular clouds, G63.7+1.1 is found to be the only one detected with neutrino emission, and the post-trail significance for the detection is 3.2 σ . Previously, this PWN was estimated to have an age of ≳8 kyr, contain a candidate pulsar detected in X-rays, and have a distance of ∼6 kpc. More importantly, and related to the PWN’s possible neutrino emission, surrounding molecular materials are seen to interact with the PWN. On the basis of these properties, we examine the proton–proton interactions as the process for the neutrino production. The PWN (or the pulsar) can provide sufficient energy to power the required high-energy (HE) protons. This possibly first neutrino-emitting case in our Galaxy, with problems or other possibilities to be solved or examined, may reveal to us that PWNe are the significant Galactic HE neutrino sources.}, archive = {J_ApJ}, author = {Shunhao Ji and Zhongxiang Wang and Dong Zheng and Jintao Zheng}, doi = {10.3847/1538-4357/adf4e0}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {142}, shortjournal = {The Astrophys. J.}, title = {Possible neutrino emission from the pulsar wind nebula g63.7+1.1}, volume = {990}, year = {2025}, }
• (2025). The orbital period changes for novae. ApJ, 990(2), 141. (www)

  @article{ , abstract = {Cataclysmic variables (CVs) are close interacting binaries in which a white dwarf accretes materials from a low-mass main-sequence companion. CVs can experience nova eruptions due to low mass transfer rates. In the standard theory of CV evolution, the ejected materials during nova eruptions are assumed to leave the system in the form of fast, isotropic, optically thick winds, which predicts that novae only result in positive variation (expansion) of the orbital period (i.e., positive Δ P ). In addition, the angular momentum losses (magnetic braking and gravitational radiation) only predict a steady long-term decay in the orbital period of CVs, i.e., \dot{P} is negative. Interestingly, an observation lasting over 30 yr reveals positive and negative values for both Δ P and \dot{P} in CVs, strongly conflicting with the standard evolutionary patterns. However, it cannot be excluded that these observations originate from short-term phenomena caused by nova eruptions because of a short timescale of observations. In this paper, we model the effect of instantaneous nova eruptions on the evolution of CVs, considering three mechanisms associated with mass loss in nova eruptions, including fast wind, the Frank jet, and binary-driven mass loss. By assuming that the observed Δ P and \dot{P} are dominated by short-term phenomena, our results show that the binary-driven mass loss can explain almost all of the observations of normal CVs. However, the Frank jet may be needed for some long-period CVs with evolved companions.}, archive = {J_ApJ}, author = {Wenshi Tang and Xiang-Dong Li and Bo Wang}, doi = {10.3847/1538-4357/adf634}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {141}, shortjournal = {The Astrophys. J.}, title = {The orbital period changes for novae}, volume = {990}, year = {2025}, }
• (2025). The dependency of bar formation timescale on disk mass fraction, toomre q, and scale height. ApJ, 990(2), 140. (www)

  @article{ , abstract = {Bars are one of the most prominent galactic structures. The classical swing-amplification theory can qualitatively describe the spontaneous bar instability of stellar disks. Still, it cannot quantify the bar formation process or explain why some disk galaxies do not have a bar. Recent studies found that the bar formation timescale depends exponentially on the disk mass fraction of the host galaxy (dubbed as “Fujii relation”), but they only explored a limited parameter space, where the physical effects of Toomre Q (local disk stability parameter) and disk scale height of the host galaxies are not fully explored. In this work, we check the robustness of the Fujii relation in a higher-dimensional parameter space of disk mass fraction, Toomre Q , and scale height. We find that the Fujii relation holds for disk galaxies with physically reasonable Toomre Q and scale height. Furthermore, the bar formation timescale also approximately linearly depends on both Toomre Q and scale height, with a more prolonged bar formation in a hotter or thicker disk. We propose an empirical relation to combine the dependency of the bar formation timescale on the three parameters. Based on the empirical relation and recent observations, we estimate that the bar formation timescale in pure stellar disks ranges from 0.2{0}_{-0.06}^{+0.09} to 12.2{0}_{-2.80}^{+3.37} Gyr or even significantly beyond the Hubble timescale in some extreme cases.}, archive = {J_ApJ}, author = {Bin-Hui Chen and Juntai Shen}, doi = {10.3847/1538-4357/adf966}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {140}, shortjournal = {The Astrophys. J.}, title = {The dependency of bar formation timescale on disk mass fraction, toomre q, and scale height}, volume = {990}, year = {2025}, }
• (2025). The atacama cosmology telescope: Machine-learning-driven tools for detecting millimeter sources in timestream preprocessing. ApJ, 990(2), 139. (www)

  @article{ , abstract = {We present a new pipeline utilizing machine learning for classifying short-duration features in raw time-ordered data (TOD) of cosmic microwave background survey observations. The pipeline, specifically designed for the Atacama Cosmology Telescope, works in conjunction with the previous TOD preprocessing techniques that employ statistical thresholding to indiscriminately remove all large spikes in the data, whether they are due to noise features, cosmic rays, or true astrophysical sources, in a process called “data cuts.” This has the undesirable effect of excising real astrophysical sources, including transients, from the data. The classification pipeline demonstrated in this work uses the output from these data cuts and is able to differentiate between electronic noise, cosmic rays, and point sources, enabling the removal of undesired signals while retaining true astrophysical signals during TOD preprocessing. We achieve an overall accuracy of 90% in categorizing data spikes of different origin and, importantly, 94% for identifying those caused by astrophysical sources. Our pipeline also measures the amplitude of any detected source seen more than once and produces a subminute-to-minute light curve, providing information on its short-timescale variability. This automated pipeline for source detection and amplitude estimation will be particularly useful for upcoming surveys with large data volumes, such as the Simons Observatory.}, archive = {J_ApJ}, author = {Simran K. Nerval and Erika Hornecker and Yilun Guan and Zeling Zhang and Adam Hincks and Emily Biermann and J. Richard Bond and Justin Clancy and Rolando Dünner and Allen Foster and Carlos Hervías-Caimapo and Renée Hložek and Thomas W. Morris and Sigurd Næss and John Orlowski-Scherer and Cristóbal Sifón and Jesse Treu}, doi = {10.3847/1538-4357/adef11}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {139}, shortjournal = {The Astrophys. J.}, title = {The atacama cosmology telescope: Machine-learning-driven tools for detecting millimeter sources in timestream preprocessing}, volume = {990}, year = {2025}, }
• (2025). Turbulent heating in collisionless low-beta plasmas: Imbalance, landau damping, and Electron–Ion energy partition. ApJ, 990(2), 138. (www)

  @article{ , abstract = {An understanding of how turbulent energy is partitioned between ions and electrons in weakly collisional plasmas is crucial for modeling many astrophysical systems. Using theory and simulations of a four-dimensional reduced model of low-beta gyrokinetics (the “Kinetic Reduced Electron Heating Model”), we investigate the dependence of collisionless heating processes on plasma beta and imbalance (normalized cross-helicity). These parameters are important because they control the helicity barrier, the formation of which divides the parameter space into two distinct regimes with remarkably different properties. In the first, at lower beta and/or imbalance, the absence of a helicity barrier allows the cascade of injected power to proceed to small (perpendicular) scales, but its slow cascade rate makes it susceptible to significant electron Landau damping, in some cases leading to a marked steepening of the magnetic spectra on scales above the ion Larmor radius. In the second, at higher beta and/or imbalance, the helicity barrier halts the cascade, confining electron Landau damping to scales above the steep “transition-range” spectral break, resulting in dominant ion heating. We formulate quantitative models of these processes that compare well to simulations in each regime, and combine them with results of previous studies to construct a simple formula for the electron–ion heating ratio as a function of beta and imbalance. This model predicts a “winner takes all” picture of low-beta plasma heating, where a small change in the fluctuations' properties at large scales (the imbalance) can cause a sudden switch between electron and ion heating.}, archive = {J_ApJ}, author = {Toby Adkins and Romain Meyrand and Jonathan Squire}, doi = {10.3847/1538-4357/ade9b0}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {138}, shortjournal = {The Astrophys. J.}, title = {Turbulent heating in collisionless low-beta plasmas: Imbalance, landau damping, and Electron–Ion energy partition}, volume = {990}, year = {2025}, }
• (2025). The multiple paths to merger of unequal-mass black hole binaries in the disks of active galactic nuclei. ApJ, 990(2), 137. (www)

  @article{ , abstract = {The accretion disks that power active galactic nuclei (AGN) are thought to house populations of stars and compact objects; after forming binaries these compact objects may merge, begetting gravitational waves (GWs) such as those detected by LIGO and VIRGO. We present a comprehensive study of the early evolution of binaries within AGN disks as their orbits are influenced by the surrounding gas, focusing on eccentric and unequal-mass binaries. Nearly equal-mass binaries behave similarly to their equal-mass counterparts: Prograde binaries inspiral, albeit somewhat slowly, and have their eccentricities damped; retrograde binaries inspiral ∼2–3 times faster than their prograde counterparts, and those with near-equal masses are driven quickly toward near-unity eccentricities. However, the primaries in retrograde binaries with mass ratios of m 2 / m 1 ≲ 0.4 experience significantly weaker headwinds and retain substantial accretion disks that help damp binary eccentricities, slowing binary inspirals. Additionally, we find that while accretion drives prograde binaries toward equal masses thanks to the exchange of material between the primary and secondary accretion disks, retrograde binaries are driven slowly toward more extreme mass ratios. Prograde binaries, and generally those with low mass ratios, likely accrete for multiple e -folding timescales before merger. On the other hand, high-mass-ratio retrograde binaries may merge before accreting substantially, potentially approaching merger with detectable eccentricity. Future ground-based GW observatories, with their broader frequency coverage, should be particularly useful for studying these populations.}, archive = {J_ApJ}, author = {Alexander J. Dittmann and Adam M. Dempsey and Hui Li}, doi = {10.3847/1538-4357/adea72}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {137}, shortjournal = {The Astrophys. J.}, title = {The multiple paths to merger of unequal-mass black hole binaries in the disks of active galactic nuclei}, volume = {990}, year = {2025}, }
• (2025). High-resolution optical IFU spectroscopy of the complex galaxy merger II zw 096. ApJ, 990(2), 136. (www)

  @article{ , abstract = {Luminous and ultraluminous IR galaxies are critical for investigating feedback mechanisms due to a combination of intense star formation episodes and active galactic nuclei (AGN), particularly in the context of complex galaxy interactions. We conduct a detailed analysis of the II ZW 096 merging system using the Multi-Unit Spectroscopic Explorer on the Very Large Telescope, combining high-resolution narrow-field mode and large-area wide-field mode observations. We mapped the morphology, kinematics, and ionizing radiation of the system’s gas by fitting atomic emission lines and the optical continuum. We identify three or more distinct galaxies within II ZW 096, revealing rotational patterns and complex interactions consistent with a collapsing small galaxy group. The kinematics and ionization structures suggest high star formation rates and shock-driven processes, which align with this proposed scenario. Focusing on the D1 compact region, which contributes 40%–70% of the system’s IR emission, and combining information from archival multiwavelength observations, we find strong evidence of a heavily obscured AGN powering it. Our analysis of the internal structure, interactions, and merger state of II ZW 096 offers novel insights into the galaxy evolution processes in this dynamic and highly chaotic system.}, archive = {J_ApJ}, author = {Clemente Riesco and Ezequiel Treister and Giacomo Venturi and Franz E. Bauer and George C. Privon and Carolina Finlez and Sandra Zamora and Dusan Tubín-Arenas and Yiqing Song and Ignacio del Moral-Castro and Claudio Ricci and Cristina Ramos Almeida and Nancy A. Levenson and Vivian U and Anne M. Medling and Susanne Aalto and Giuseppe D’Ago and Valeria Olivares and Loreto Barcos Muñoz and Federica Ricci and Gustav Olander and Francisco Muller-Sanchez and Patricia B. Tissera}, doi = {10.3847/1538-4357/adee18}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {136}, shortjournal = {The Astrophys. J.}, title = {High-resolution optical IFU spectroscopy of the complex galaxy merger II zw 096}, volume = {990}, year = {2025}, }
• (2025). ΛCDM star clusters at cosmic dawn: Stellar densities, environment, and equilibrium. ApJ, 990(2), 135. (www)

  @article{ , abstract = {The James Webb Space Telescope (JWST) has opened a window on many new puzzles in the early Universe, including a population of high-redshift star clusters with extremely high stellar surface density, suggesting unique star formation conditions in the Universe’s early evolution. We study the formation and evolution of these first star clusters and galaxies using an AREPO cosmological simulation box designed to resolve the intricate environments of the smallest halos hosting Population III star clusters at z ≥ 12. Our approach, which prioritizes baryonic structure identification through a friends-of-friends algorithm, provides new insights into early star cluster formation and delivers predictions directly relevant to observations. We investigate the dynamical properties of these first star clusters and use numerical and analytical methods to understand the populations of virialized and nonvirialized systems. Our findings indicate that high- z star clusters in a feedback-free regime can achieve extreme surface densities, consistent with the systems detected by JWST. These results imply that JWST may have the opportunity to uncover stellar systems at high redshift whose dynamical state preserves evidence of the hierarchical structure formation process.}, archive = {J_ApJ}, author = {Claire E. Williams and Smadar Naoz and William Lake and Blakesley Burkhart and Federico Marinacci and Mark Vogelsberger and Naoki Yoshida and Shyam H. Menon and Avi Chen and Angela Adamo}, doi = {10.3847/1538-4357/adf19d}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {135}, shortjournal = {The Astrophys. J.}, title = {ΛCDM star clusters at cosmic dawn: Stellar densities, environment, and equilibrium}, volume = {990}, year = {2025}, }
• (2025). Using the hanle effect in mg ii k to quantify the open flux above the solar poles. ApJ, 990(2), 134. (www)

  @article{ , abstract = {We test the use of the Mg ii resonant lines for measurement of the magnetic field at the top of the chromosphere of polar coronal holes (CHs). The Hanle effect in the core of Mg II k enables access to a regime of field strengths where the Zeeman effect has little diagnostic value (especially at the solar poles, where most of the field is transverse to the line of sight). Synthetic Stokes spectra computed from a radiation magnetohydrodynamic simulation of a CH emulating a high viewing angle are inverted with the HanleRT Tenerife Inversion Code, which accounts for the physical processes that lead to scattering-induced polarization and its modification due to the magnetic field and other symmetry-breaking mechanisms. We find that, while degeneracies in the atmospheric model lead to poor inferences of the thermodynamical properties, the magnetic inferences are highly consistent with the model values. The mean magnetic field strength in the simulation cube is typically retrieved with a relative error of δB ∼ 20% and an absolute error of Δ B ∼ 2 G at the top of the chromosphere. This opens up an avenue for promising chromospheric constraints for magnetic extrapolation models that ingest photospheric magnetograms, whose biases and uncertainties are troublesome to the reconstruction of the heliospheric magnetic field.}, archive = {J_ApJ}, author = {Ryan A. Hofmann and David Afonso Delgado and Rebecca Centeno and Roberto Casini and Matthias Rempel and Tanausú del Pino Alemán}, doi = {10.3847/1538-4357/adf228}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {134}, shortjournal = {The Astrophys. J.}, title = {Using the hanle effect in mg ii k to quantify the open flux above the solar poles}, volume = {990}, year = {2025}, }
• (2025). A comparison of full spectral fitting codes for measuring the stellar initial mass function and other stellar population properties in elliptical galaxies*. ApJ, 990(2), 133. (www)

  @article{ , abstract = {We present a comparative test of four widely used full spectral fitting codes, with the aim of answering the question: How robust is the retrieval of the stellar initial mass function (IMF) and other stellar properties of galaxies? We used Absorption Line Fitter ( ALF ), Python Stellar Absorption Feature Fitting ( PyStaff ), Starlight, and Penalized PiXel-Fitting ( pPXF) to fit a set of optical+near-IR spectroscopic data from the Magellan telescope of the two brightest galaxies in the Fornax cluster, NGC 1399 and NGC 1404. By fitting the same data set with the same models, we can compare the radial trends (out to ∼1 R e ) of IMF slope, age, metallicity, and 19 elemental abundances when allowed with the four codes. To further test the robustness of our analysis, we carried out parallel simulations by creating inputs with different star formation history (SFH) complexity. The results from simulations show that codes such as ALF and PyStaff , which both assume a simple stellar population (SSP), return greater precision and accuracy only when the underlying population is a pure SSP; however, in cases where the SFH is more complex, these codes return erroneous results. Although codes like Starlight and pPXF , which retrieve the best-fit SFH without prior assumptions, tend to produce results with greater scatter and bias, they are generally more reliable in identifying secondary components. Our analysis on the two targets shows that ALF and PyStaff , which assume an SSP, give results pointing to a single old age, a decreasing metallicity with radius, and a flat super-Salpeter IMF. In contrast, Starlight and pPXF suggest the presence of a secondary component with different metallicity and IMF characteristics.}, archive = {J_ApJ}, author = {Ilaria Lonoce and Anja Feldmeier-Krause and Alexandra Masegian and Wendy L. Freedman}, doi = {10.3847/1538-4357/adf3a9}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {133}, shortjournal = {The Astrophys. J.}, title = {A comparison of full spectral fitting codes for measuring the stellar initial mass function and other stellar population properties in elliptical galaxies*}, volume = {990}, year = {2025}, }
• (2025). R-process abundance dispersion in the globular cluster m5 using keck archival data. ApJ, 990(2), 132. (www)

  @article{ , abstract = {We studied 28 red giant branch stars in the mildly metal-rich globular cluster M5 ([Fe/H] = −1.29) using archival high-resolution spectra from the Keck Observatory archive to better understand the r -process in globular clusters. Previous studies (M15, M92, and NGC 2298) have shown r -process dispersion in varying amounts, hinting at the source of the r -process in those clusters. We extend these dispersion studies to the more metal-rich cluster M5 by studying the rare-earth peak, specifically the elements Ba, Nd, and Eu. We separately analyze the different stellar generations, as traced by the abundance of Na and O. Based on the Nd and Eu abundances, we report a tenuous detection of r -process dispersion that is dependent on the generation and element. Based on a log-likelihood dispersion study accounting for measurement errors, Nd has an intrinsic first-generation abundance spread of {\sigma }_{1{\rm{G}}}(\,\rm{Nd}\,)=0.1{5}_{-0.07}^{+0.10} and a 2 σ upper limit on the second-generation spread of σ 2G (Nd) < 0.28. The upper limits on the Eu intrinsic spread are σ 1G (Eu) < 0.34 and σ 2G (Eu) < 0.16. A potential dispersion implies the cluster gas was inhomogeneously polluted, either due to an event concurrent with the formation of the cluster or due to clouds of disparate composition that coalesced to form the cluster.}, archive = {J_ApJ}, author = {Pranav Nalamwar and Evan N. Kirby and Alice Cai}, doi = {10.3847/1538-4357/adf3ad}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {132}, shortjournal = {The Astrophys. J.}, title = {R-process abundance dispersion in the globular cluster m5 using keck archival data}, volume = {990}, year = {2025}, }
• (2025). Formation of a nuclear star cluster through a merger event in the low-surface-brightness galaxy AGC 223218. ApJ, 990(2), 131. (www)

  @article{ , abstract = {We present the properties of a nuclear star cluster (NSC) in the low-surface-brightness galaxy AGC 223218. The disk of the galaxy can be modeled using two Sérsic components with distinct central positions: one representing the inner bright disk and the other corresponding to the extended outer disk. We estimate the stellar masses of the NSC and the host galaxy using two methods: spectral energy distribution (SED) fitting and mass-to-light versus color relations (MLCRs). The stellar mass ratio of the NSC to AGC 223218 is 0.094 based on the SED method and 0.072 using MLCRs. The NSC presents a younger stellar population and a lower [Fe/H] value than the host, as determined from Sloan Digital Sky Survey (SDSS) and LAMOST spectra analysis using pPXF fitting. AGC 223218 is located at the boundary between the Seyfert and star-forming regions in the [S II ]-Baldwin–Phillips–Terlevich (BPT) diagram, whereas in the [N II ]-BPT diagram, it falls in the track of star-forming SDSS galaxies. This suggests the presence of strong shocks in AGC 223218. We propose that the NSC in AGC 223218 may have formed as a result of a merger event. Furthermore, the observed X-ray luminosity of AGC 223218 with eROSITA is 2 orders of magnitude higher than the expected X-ray luminosity from X-ray binaries, suggesting the presence of an intermediate-mass black hole (IMBH) in the NSC. To account for the observed X-ray luminosity, we estimate the IMBH accretion rate to be approximately 0.001.}, archive = {J_ApJ}, author = {Tian-Wen Cao and Zi-Qi Chen and Zi-Jian Li and Cheng Cheng and Gaspar Galaz and Venu M. Kalari and Jun-feng Wang and Chun-Yi Zhang and Pei-Bin Chen and Meng-Ting Shen and Hong Wu}, doi = {10.3847/1538-4357/adf559}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {131}, shortjournal = {The Astrophys. J.}, title = {Formation of a nuclear star cluster through a merger event in the low-surface-brightness galaxy AGC 223218}, volume = {990}, year = {2025}, }
• (2025). Considering contact forces during the formation of planetesimals by gravitational collapse: Mutual orbits, spin states, and shapes. ApJ, 990(2), 130. (www)

  @article{ , abstract = {In this work, we apply a soft-sphere discrete element method (SSDEM) within the PKDGRAV N -body integrator to investigate the formation of planetesimal systems through the gravitational collapse of clouds of superparticles. Previously published numerical models have demonstrated that the gravitational collapse of pebble clouds is an efficient pathway to produce binary planetesimal systems. However, such investigations were limited by their use of a perfect-merger and inflated-radii superparticle approach, which inhibits any analysis of planetesimal shapes and spin states, precludes the formation of the tightest binary orbits, and produces significantly underdense planetesimals. The SSDEM enables superparticles to rest upon each other through mutual surface penetration and by simulating contact physics. Superparticles do not need to be inflated, and collisions are not treated as perfect mergers; we can thus track the evolution of planetesimal shapes, spins, and tight binary orbits. We demonstrate that the SSDEM is an excellent method to model the collapse process, and is capable of producing many binary planetesimal systems from a single cloud. The most massive systems often exhibit low-inclination ( i ≲ 15°) and moderately eccentric ( e ≲ 0.40) orbits within a tight range of semimajor axes normalized by their Hill radii ( a / R Hill ∼ 0.02–0.15). Conversely, less massive planetesimal systems display a wider range of eccentricities and inclinations and maintain a wider range of a / R Hill (0.15 to ≥0.50). These results confirm the findings of previously published perfect-merging models while also producing novel results about planetesimal spin and shape properties. Newly formed planetesimals exhibit 10 hr rotation periods on average and can be characterized by a wide variety of shapes (spherical, oblate, top-shaped, flattened, egg-shaped, or prolate), with the most massive planetesimals primarily forming as spheres and oblate spheroids.}, archive = {J_ApJ}, author = {Jackson T. Barnes and Stephen R. Schwartz and Seth A. Jacobson}, doi = {10.3847/1538-4357/ade142}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {130}, shortjournal = {The Astrophys. J.}, title = {Considering contact forces during the formation of planetesimals by gravitational collapse: Mutual orbits, spin states, and shapes}, volume = {990}, year = {2025}, }
• (2025). Effect of positronium on the γ-ray spectra and energy deposition in type ia supernovae. ApJ, 990(2), 129. (www)

  @article{ , abstract = {Type Ia supernovae (SNe Ia) are powered by the radioactive decay of isotopes such as 56 Ni and 56 Co, making their γ -ray spectra useful probes of the explosion mechanism and ejecta structure. Accurate interpretation of γ -ray observables, including line ratios and continuum fluxes, requires a detailed understanding of the microphysical processes that shape the spectra. One such process is positronium formation during electron–positron annihilation, which can redistribute flux from the 511 keV line into the surrounding continuum. To assess the impact of positronium on the emergent spectra, we developed a new open-source module, tardis-He , for time-dependent three-dimensional γ -ray transport, integrated into the radiative transfer code tardis . The code simulates γ -ray spectra and light curves from one-dimensional supernova ejecta models and allows for flexible incorporation of decay chains and opacity treatments. Using tardis-He , we explore the effect of positronium formation by varying the positronium fraction from 0% to 100%, and assuming an extreme case where 75% of positronium decays result in three-photon emission. We find that full positronium formation can reduce the 511 keV line flux by ≈70% and modestly enhance energy deposition by up to 2% at around 100 days postexplosion, compared to models without positronium. These results demonstrate that, while the effect is not dominant, positronium formation introduces measurable changes to γ -ray observables. Future observations with missions such as the Compton Spectrometer and Imager may offer constraints on positronium formation in SNe Ia and help refine models of their radioactive energy transport.}, archive = {J_ApJ}, author = {Anirban Dutta and Andrew G. Fullard and Wolfgang E. Kerzendorf and J. T. O’Brien and Cecelia Powers and Stuart A. Sim and Andreas Flörs and Or Graur}, doi = {10.3847/1538-4357/ade880}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {129}, shortjournal = {The Astrophys. J.}, title = {Effect of positronium on the γ-ray spectra and energy deposition in type ia supernovae}, volume = {990}, year = {2025}, }
• (2025). The parallel diffusion coefficient of energetic particles in a spatially varying magnetic field. ApJ, 990(2), 128. (www)

  @article{ , abstract = {In the theory of energetic particle transport, the spatial variation of large-scale magnetic fields gives rise to a so-called adiabatic focusing term in the pitch-angle-dependent transport equation. This focusing term leads to the effect of convection, but it also alters the parallel spatial diffusion coefficient. Over the past few decades researchers have tried to derive analytical forms for the parallel diffusion coefficient as a function of the focusing length. Two different results have been derived contradicting each other. In the current paper we revisit this problem and provide the final solution. We combine previously developed numerical methods such as the subspace approach, allowing us to compute the parallel diffusion coefficient as a function of the focusing length with very high precision within a very short computational time. Most importantly, we derive an exact formula for the diffusion coefficient by employing analytical theory. The new formula agrees perfectly with the numerically obtained results proofing its validity.}, archive = {J_ApJ}, author = {A. Shalchi and B. Klippenstein}, doi = {10.3847/1538-4357/adea53}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {128}, shortjournal = {The Astrophys. J.}, title = {The parallel diffusion coefficient of energetic particles in a spatially varying magnetic field}, volume = {990}, year = {2025}, }
• (2025). The outskirt stellar mass of low-redshift massive galaxies is an excellent halo mass proxy in Illustris/IllustrisTNG simulations. ApJ, 990(2), 127. (www)

  @article{ , abstract = {Recent observations suggest that the extended stellar halos of low-redshift massive galaxies are tightly connected to the assembly of their dark matter halos. In this paper, we use the Illustris , IllustrisTNG 100, and IllustrisTNG 300 simulations to compare how different stellar aperture masses trace halo mass. For massive central galaxies ( M ⋆ ≥ 10 11.2 M ⊙ ), we find that a 2D outskirt stellar mass measured between 50 and 100 kpc ( M ⋆,[50,100] ) consistently outperforms other aperture-based stellar masses. We further show that M ⋆,[50,100] correlates better with halo mass than the total mass of accreted stars (the ex situ mass), which suggests that not all accreted stars connect to halo assembly equally. While the galaxy formation recipes differ between Illustris and IllustrisTNG 100, the two simulations yield consistent ex situ outskirt fractions for massive galaxies (∼70% in M ⋆,[50,100] ). These results demonstrate the potential of using the outskirt stellar mass to deepen our understanding of the galaxy–halo connection in massive dark matter halos and to trace dark matter halos better.}, archive = {J_ApJ}, author = {Shuo Xu and Song Huang and Alexie Leauthaud and Benedikt Diemer and Katya Leidig and Carlo Cannarozzo and Conghao Zhou}, doi = {10.3847/1538-4357/adeca0}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {127}, shortjournal = {The Astrophys. J.}, title = {The outskirt stellar mass of low-redshift massive galaxies is an excellent halo mass proxy in Illustris/IllustrisTNG simulations}, volume = {990}, year = {2025}, }
• (2025). The shape of AGN-driven winds in the seyfert galaxy NGC 3516. ApJ, 990(2), 126. (www)

  @article{ , abstract = {Active galactic nuclei (AGN) are known to drive ionized gas into their host galaxies, which may affect the evolution of both the central supermassive black holes and their hosts. In the case of NGC 3516, a nearby Seyfert 1 galaxy, these AGN winds have historically proven difficult to disentangle from galactic rotation. Using long-slit spectroscopy at multiple position angles from Hubble Space Telescope’s Space Telescope Imaging Spectrograph and Apache Point Observatory’s Kitt Peak Ohio State Multi-Object Spectrograph, we separate these kinematic components by fitting multiple Gaussians to the H α , [N II ], H β , and [O III ] emission lines along the slits. We present a biconical outflow model that agrees well with the observed kinematics of the outflowing gas in the narrow-line region (NLR). Our results indicate that the structure of the [O III ] emission is explained by dusty gas spirals in the galactic disk that are illuminated by the ionizing bicone, which is viewed along one edge, resulting in the complex nuclear kinematics. Our view into the bicone edge is consistent with the multiple, deep components of ionized absorption lines seen in UV and X-ray spectra of NGC 3516. The observed turnover in the velocity of the NLR clouds matches that from a simple dynamical model of radiative acceleration by the AGN and gravitational deceleration by the AGN and galaxy, indicating they are the principal forces at work on the gas clouds. Finally, the model launch radii indicate that the outflowing clouds originate primarily from the inner dusty spirals near the AGN.}, archive = {J_ApJ}, author = {Jacob Tutterow and Nicolas Ferree and D. Michael Crenshaw and Julia Falcone and Maura Kathleen Shea and Travis C. Fischer and Beena Meena and Mitchell Revalski and Kesha Patel and Madeline Davis}, doi = {10.3847/1538-4357/adf055}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {126}, shortjournal = {The Astrophys. J.}, title = {The shape of AGN-driven winds in the seyfert galaxy NGC 3516}, volume = {990}, year = {2025}, }
• (2025). The R-process alliance: Enrichment of r-process elements in a simulated milky way–like galaxy. ApJ, 990(2), 125. (www)

  @article{ , abstract = {We study the formation of stars with varying amounts of heavy elements synthesized by the rapid neutron-capture process ( r -process) based on our detailed cosmological zoom-in simulation of a Milky Way–like galaxy with an N -body/smoothed particle hydrodynamics code, asura . Most stars with no overabundance in r -process elements, as well as the strongly r -process-enhanced (RPE) r -II stars ([Eu/Fe] > +0.7), are formed in dwarf galaxies accreted by the Milky Way within the 6 Gyr after the Big Bang. In contrast, over half of the moderately enhanced r -I stars (+0.3 < [Eu/Fe] ≤ +0.7) are formed in the main in situ disk after 6 Gyr. Our results suggest that the fraction of r -I and r -II stars formed in disrupted dwarf galaxies is larger the higher their [Eu/Fe] is. Accordingly, the most strongly enhanced r -III stars ([Eu/Fe] > +2.0) are formed in accreted components. These results suggest that non- r -process-enhanced stars and r -II stars are mainly formed in low-mass dwarf galaxies that hosted either none or a single neutron star merger, while the r -I stars tend to form in the well-mixed in situ disk. We compare our findings with high-resolution spectroscopic observations of RPE metal-poor stars in the halo and dwarf galaxies, including those collected by the R -Process Alliance. We conclude that observed [Eu/Fe] and [Eu/Mg] ratios can be employed in chemical tagging of the Milky Way’s accretion history.}, archive = {J_ApJ}, author = {Yutaka Hirai and Timothy C. Beers and Young Sun Lee and Shinya Wanajo and Ian U. Roederer and Masaomi Tanaka and Masashi Chiba and Takayuki R. Saitoh and Vinicius M. Placco and Terese T. Hansen and Rana Ezzeddine and Anna Frebel and Erika M. Holmbeck and Charli M. Sakari}, doi = {10.3847/1538-4357/adf10a}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {125}, shortjournal = {The Astrophys. J.}, title = {The R-process alliance: Enrichment of r-process elements in a simulated milky way–like galaxy}, volume = {990}, year = {2025}, }
• (2025). Tidal synchronization of TESS eclipsing binaries. ApJ, 990(2), 124. (www)

  @article{ , abstract = {Tidal synchronization plays a fundamental role in the evolution of binary star systems. However, key details such as the timescale of synchronization, efficiency of tidal dissipation, rotation period, and dependence on stellar mass are not well constrained. We present a catalog of rotation periods, orbital periods, and eccentricities from eclipsing binaries (EBs) that can be used to study the role of tides in the rotational evolution of low-mass dwarf (FGKM spectral type) binaries. This study presents the largest catalog of EB orbital and rotational periods ( P orb and P rot ) measured from the Transiting Exoplanet Satellite Survey (TESS). We first classify 4584 light curves from the TESS EB catalog according to out-of-eclipse stellar variability type: starspot modulation, ellipsoidal variability, nonperiodic variability, and “other” variability (e.g., pulsations). We then manually validate each light curve’s classification, resulting in a sample of 1039 candidates with 584 high-confidence EBs that exhibit detectable starspot modulation. From there, we measure and compare the rotation period of each starspot-modulated EB using three methods: a Lomb–Scargle periodogram, autocorrelation function, and phase dispersion minimization. We find that our period distributions are consistent with previous work that used a sample of 816 starspot EBs from Kepler to identify two populations: a synchronous population (with P orb ≈ P rot ), and a subsynchronous population (with 8 P orb ≈ 7 P rot ). Using Bayesian model comparison, we find that a bimodal distribution is a significantly better fit than a unimodal distribution for the Kepler and TESS samples, both individually or combined, confirming that the subsynchronous population is statistically significant.}, archive = {J_ApJ}, author = {Marshall Hobson-Ritz and Jessica Birky and Leah Peterson and Peter Gwartney and Rachel Wong and John Delker and Tyler Gordon and Samantha Gilbert and James R. A. Davenport and Rory Barnes}, doi = {10.3847/1538-4357/adf10d}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {124}, shortjournal = {The Astrophys. J.}, title = {Tidal synchronization of TESS eclipsing binaries}, volume = {990}, year = {2025}, }
• (2025). Early-type galaxies on the star formation main sequence: Internal star formation geometries revealed with MaNGA and their environmental origin. ApJ, 990(2), 123. (www)

  @article{ , abstract = {Star-forming galaxies on the main sequence (MS) are often regarded as a uniform population characterized by similar global star formation properties. However, there exists a diversity in galaxy morphologies at a fixed stellar mass and star formation rate. In this study, using spatially resolved properties from the MaNGA final data release, we classify MS galaxies into late type (MS-late) and early type (MS-early). In addition, we further divide the MS-early galaxies into two distinct subgroups based on their internal star formation and stellar mass distributions within the galaxies. The first group—“MS-early_SF”—shows centrally concentrated star formation without prominent stellar bulges and resides preferentially in dense environments, suggesting environmentally driven evolution. The second group—“MS-early_stellar”—exhibits significant stellar bulges with suppressed central star formation, maintains disk-like star formation patterns, and inhabits environments similar to those of late-type galaxies, indicating evolution through internal secular processes. Our findings demonstrate that spatially resolved observations play critical roles in revealing the diverse evolutionary pathways hidden within galaxies that share similar global properties.}, archive = {J_ApJ}, author = {Shuhei Koyama and Yusei Koyama and Takuji Yamashita and Masahiro Konishi and Kosuke Kushibiki and Kentaro Motohara}, doi = {10.3847/1538-4357/adf1a8}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {123}, shortjournal = {The Astrophys. J.}, title = {Early-type galaxies on the star formation main sequence: Internal star formation geometries revealed with MaNGA and their environmental origin}, volume = {990}, year = {2025}, }
• (2025). Application of physics-informed neural networks in removing telescope beam effects. ApJ, 990(2), 122. (www)

  @article{ , abstract = {This study introduces PI-AstroDeconv , a physics-informed semi-supervised learning method specifically designed for removing beam effects in astronomical telescope observation systems. The method utilizes an encoder–decoder network architecture and combines the telescope’s point-spread function or beam as prior information, while integrating Fast Fourier Transform–accelerated convolution techniques into the deep learning network. This enables the effective removal of beam effects from astronomical observation images. PI-AstroDeconv can handle multiple point-spread functions or beams, tolerate imprecise measurements to some extent, and significantly improve the efficiency and accuracy of image deconvolution. Therefore, this architecture is particularly suitable for astronomical data processing that does not rely on annotated data. To validate the reliability of the architecture, we used the Square Kilometre Array Science Data Challenge 3a data sets and compared it with the CLEAN deconvolution method at the 21 cm power spectrum level. The results demonstrate that our algorithm not only restores details and reduces blurriness in celestial images at the pixel level, but also more accurately recovers the true neutral hydrogen power spectrum at the power spectrum level.}, archive = {J_ApJ}, author = {Shulei Ni and Yisheng Qiu and Yunchuan Chen and Zihao Song and Hao Chen and Xuejian Jiang and Di Li and Donghui Quan and Huaxi Chen}, doi = {10.3847/1538-4357/adf223}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {122}, shortjournal = {The Astrophys. J.}, title = {Application of physics-informed neural networks in removing telescope beam effects}, volume = {990}, year = {2025}, }
• (2025). Tracing magnetic signatures through the solar atmosphere in seven eruptive active regions. ApJ, 990(2), 121. (www)

  @article{ , abstract = {This case study focuses on the pre-eruptive conditions of active regions that produced either low-energy flares accompanied by major CMEs (AR 12371 and AR 11692) or major X-class flares also associated with significant CMEs (AR 12673, AR 12158, AR 11520, AR 11429, and AR 13664). The study examines the evolution of 10 morphological parameters that serve as indicators of pre-eruptive conditions—not only at the photosphere but also in higher layers of the solar atmosphere. We found that active regions with a greater number of parameters exceeding their threshold values at higher altitudes tend to exhibit a higher eruptive potential. Specifically, in active regions associated with X-class flares and fast CMEs, at least 8 out of 10 parameters exceeded their thresholds at elevated layers, whereas in the 2 active regions linked to M-class flares and fast CMEs, fewer than 7 parameters did so. These results suggest that assessing the height-dependent behavior of pre-eruptive proxy parameters could significantly improve the identification and prediction of eruptive active regions. Future studies should extend this approach to a larger data set to better determine the maximum atmospheric height at which the predictive thresholds of different parameters are met, thereby enhancing the accuracy of solar eruption prediction.}, archive = {J_ApJ}, author = {Marianna B. Korsós and Ioannis Kontogiannis and Daria Shukhobodskaia and Luciano Rodriguez and Fabiana Ferrente and Francesca Zuccarello}, doi = {10.3847/1538-4357/adf2a7}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {121}, shortjournal = {The Astrophys. J.}, title = {Tracing magnetic signatures through the solar atmosphere in seven eruptive active regions}, volume = {990}, year = {2025}, }
• (2025). The astrid simulation: Evolution of black holes and galaxies to z = 0.5 and different evolution pathways for galaxy quenching. ApJ, 990(2), 120. (www)

  @article{ , abstract = {We present new results from the ASTRID simulation from z = 3 to z = 0.5, covering the epoch of cosmic noon. The galaxy stellar mass function, as well as the black hole mass and luminosity functions in ASTRID , exhibit good agreement with recent observational constraints. We study the M BH – M * scaling relation and its connections to active galactic nucleus (AGN) luminosity, galaxy color, and star formation rate, demonstrating that AGN feedback plays a crucial role in the quenching of massive galaxies ( M * > 10 10.5 M ⊙ ). Although AGN feedback ultimately suppresses star formation through quenching, AGN-host galaxies can still exhibit statistically higher star formation rates than inactive ones, reflecting a positive correlation driven by their shared dependence on a common cold gas reservoir. The fraction of quiescent galaxies in ASTRID increases with both galaxy mass and redshift evolution, aligning well with observational trends. We find that different quenching mechanisms can leave distinct morphological imprints on quenched galaxies. Massive, compact quiescent galaxies typically experience shorter quenching timescales, have younger central regions, and host overmassive black holes. This is usually due to a compaction-like quenching mechanism that funnels gas into the galactic center, leading to starbursts and triggering AGN kinetic feedback. In contrast, quiescent galaxies with more diffuse morphologies generally experience “inside-out” quenching, which is characterized by older central regions compared to the outskirts. These galaxies typically experience longer quenching timescales due to quenching processes operating on a larger halo scale, which gradually deplete the galactic star-forming gas. Data of the ASTRID simulation down to z = 0.5 is available at https://astrid.psc.edu .}, archive = {J_ApJ}, author = {Yueying Ni and Nianyi Chen and Yihao Zhou and Minjung Park and Yanhui Yang and Tiziana Di Matteo and Simeon Bird and Rupert Croft}, doi = {10.3847/1538-4357/adf3a7}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {120}, shortjournal = {The Astrophys. J.}, title = {The astrid simulation: Evolution of black holes and galaxies to z = 0.5 and different evolution pathways for galaxy quenching}, volume = {990}, year = {2025}, }
• (2025). GrAviPaSt’s lens to the past: Unveiling the evolution of filamentary structures. ApJ, 990(2), 119. (www)

  @article{ , abstract = {This paper examines the evolution of cosmic filaments across redshifts 1, 0.5, and 0 using the IllustrisTNG100-1 magnetohydrodynamical simulation. To achieve this, we introduce GrAviPaSt, a simple, efficient, and parameter-free filament identification method that leverages gravitational potential, an A*-like pathfinding algorithm, and spanning trees. Applying this method to galaxy distributions at different redshifts allows us to analyze various filament properties, including their length, thickness, mass density contrast, and radial profile. Additionally, we investigate dynamic characteristics such as the mean distance of filament galaxies from the skeleton, their weighted mean velocity, and velocity trends normalized by their positions within the filaments. Our findings reveal the evolution of cosmic filaments from redshift 1–0, highlighting key differences across classifications. In particular, we examine the mass density contrast radial profile of filaments connecting two galaxy groups and those linking two galaxy clusters, identifying distinct differences in profile shape between these categories. Furthermore, in the context of weighted mean velocity, we analyze cosmic filaments exhibiting either negative or positive weighted mean velocity, demonstrating their differing evolutionary trends in terms of the mean distance of filament galaxies from the skeleton.}, archive = {J_ApJ}, author = {Parsa Ghafour and Saeed Tavasoli}, doi = {10.3847/1538-4357/adf3b2}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {119}, shortjournal = {The Astrophys. J.}, title = {GrAviPaSt’s lens to the past: Unveiling the evolution of filamentary structures}, volume = {990}, year = {2025}, }
• (2025). Invisible accretion: Ionized envelopes of TNG50 HVCs can sustain star formation. ApJ, 990(2), 118. (www)

  @article{ , abstract = {Galactic high-velocity clouds (HVCs) are known to be complex, multiphase systems consisting of neutral and/or ionized gas moving at high velocities relative to the rotation of the disk. In this work, we investigate Milky Way–like galaxies from the TNG50 simulation to characterize the properties, morphology, and accretion rates of the warm and hot ionized material comoving with neutral HVCs visible in H i . We find that the ionized gas forms an envelope around the neutral material, and in most cases (73% of the HVCs), it is prolate in morphology. We also find that the ionized mass is ∼6 times greater than the neutral mass, which leads to significantly more accretion being possible from the ionized gas ( {\dot{M}}_{{\rm{ion}}} ) than the neutral gas ( {\dot{M}}_{{\rm{neut}}} ), consistent with estimates made from observations of our own Galaxy. We investigate the accretion rates from both phases of HVCs around 47 Milky Way–like galaxies, finding that {\dot{M}}_{{\rm{ion}}} scales with {\dot{M}}_{{\rm{neut}}} and both scale with the star formation rate of the galaxy. Finally, we find that, on average, {\dot{M}}_{{\rm{ion}}} could account for 81% of the galactic star formation rate (assuming the material can sufficiently cool and condense), while {\dot{M}}_{{\rm{neut}}} can only balance 11%. Thus, the diffuse, ionized, high-velocity circumgalactic medium plays a defining role in the evolution and growth of galaxies at low redshift.}, archive = {J_ApJ}, author = {Scott Lucchini and Jiwon Jesse Han and Lars Hernquist and Charlie Conroy and Andrew J. Fox}, doi = {10.3847/1538-4357/adf3b3}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {118}, shortjournal = {The Astrophys. J.}, title = {Invisible accretion: Ionized envelopes of TNG50 HVCs can sustain star formation}, volume = {990}, year = {2025}, }
• (2025). The response of planetary atmospheres to the impact of icy comets. II. exo-earth analogs. ApJ, 990(2), 117. (www)

  @article{ , abstract = {The orbital regime of a terrestrial planet plays a significant role in shaping its atmospheric dynamics, climate, and hence potential habitability. The orbit is also likely to play a role in shaping the response of a planetary atmosphere to the influx of material from an icy cometary impact. To investigate this response, we model the impact of an icy cometary body with an Earth-analog exoplanet (i.e., an Earth-like planet orbiting a Sun-like star with a diurnal cycle) using a cometary impact and breakup model coupled with the 3D Earth system model WACCM6/CESM2. To quantify the role that the atmospheric dynamics play in setting the response to a cometary impact, we compare our results with a previous study investigating an impact with a tidally locked terrestrial exoplanet. We find that the circulation regime of the planet plays a key role in shaping the response of the atmosphere to an icy cometary impact. The weak multicelled circulation structure that forms on Earth-like planets is efficient at mixing material horizontally but not vertically, limiting the transport of water from the deep breakup site to higher altitudes. In turn, this limits the rate of water photodissociation at low pressures, reducing the magnitude of postimpact changes to composition. It also reduces the potential observability of an impact due to weakened cloud ice formation, and hence scattering, at low pressures. Despite this, small changes to the overall composition of the planet persist to a quasi steady state, reinforcing the idea that ongoing bombardment may help to shape the composition/habitability of terrestrial worlds.}, archive = {J_ApJ}, author = {F. Sainsbury-Martinez and C. Walsh}, doi = {10.3847/1538-4357/adf43c}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {117}, shortjournal = {The Astrophys. J.}, title = {The response of planetary atmospheres to the impact of icy comets. II. exo-earth analogs}, volume = {990}, year = {2025}, }
• (2025). A drag-force analysis of solar wind white-light tracers in the inner heliosphere. ApJ, 990(2), 116. (www)

  @article{ , abstract = {We studied the propagation of blobs, which are a subset of density mesoscale structures observed in the solar corona. The detection of blobs in white-light data was performed during Solar Cycle 23. Blobs are tracers of the solar wind and an important source of its variability. We analyzed the deprojected blob radial elongation and kinematics as they evolved in the inner heliosphere using a dynamical “drag-force” model. We characterized 13 blob-like structures detected by Large Angle Spectrometric Coronagraph and SECCHI coronagraphs aboard Solar and Heliospheric Observatory and Solar TErrestrial RElations Observatory, respectively. We applied, for the first time, analysis techniques that were typically used for coronal mass ejections to these compact plasma blobs that seem to propagate “passively” with the solar wind. This is the first time that the mass of blobs has been reported, with a mean value of 3.32 ± 0.19 × 10 12 g . In addition, blobs show a mean radial expansion rate of 1.10 ± 0.96 × 10 −1 R ⊙ hr −1 . We assumed that the blob movement is governed by a force that is active at a heliocentric distance ∼5 R ⊙ , “dragging” blobs near the Sun outward until they reached a mean final velocity of 427 ± 55 km s −1 at ∼15 R ⊙ . According to the physical parameters involved in this “drag-force” model, the best estimate of the dynamic viscosity of the ambient solar wind is 1.27 ± 0.98 × 10 −4 g cm −1 s −1 . This is also the first time that this crucial parameter for aerodynamical studies has been reported close to the Sun.}, archive = {J_ApJ}, author = {Cynthia López-Portela and Mari Paz Miralles and Alejandro Lara}, doi = {10.3847/1538-4357/adf4da}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {116}, shortjournal = {The Astrophys. J.}, title = {A drag-force analysis of solar wind white-light tracers in the inner heliosphere}, volume = {990}, year = {2025}, }
• (2025). Statistical analysis of ion properties in the martian magnetosheath based on MAVEN observations: A comparison of core and total ion populations. ApJ, 990(2), 115. (www)

  @article{ , abstract = {This study statistically compares ion properties between the thermal core and total ion populations in the Martian magnetosheath, based on observations collected by the Mars Atmosphere and Volatile EvolutioN (or MAVEN) spacecraft from 2015 to 2023. Ion moments for the core population are derived by fitting measured three-dimensional ion velocity distributions with bi-Maxwellian functions, whereas those for the total population are obtained by directly computing weighted sums over the distributions. The core population accounts for a median of approximately 80% of the total number density and dominates the bulk flow of the total population. In contrast, the total population exhibits significantly higher temperature, thermal pressure, and plasma beta, primarily due to the presence of suprathermal ions. Both populations exhibit greater temperature anisotropies downstream of quasi-perpendicular shocks compared to quasi-parallel shocks, consistent with stronger shock compression and a greater contribution from gyrating reflected ions under quasi-perpendicular conditions. Notably, the core population consistently exhibits significantly higher temperature anisotropy than the total population under both shock geometries, suggesting the presence of additional perpendicular heating mechanisms acting on the core population beyond shock compression. One plausible mechanism is stochastic energization by kinetic Alfvén waves. Overall, this systematic comparison of ion parameters between the core and total populations provides new insights into the thermodynamic structure and governing processes of the Martian magnetosheath.}, archive = {J_ApJ}, author = {Han-Wen Shen and Jasper S. Halekas and Shannon M. Curry and Chi Zhang and Yuanzheng Wen and Jared R. Espley}, doi = {10.3847/1538-4357/adf6a9}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {115}, shortjournal = {The Astrophys. J.}, title = {Statistical analysis of ion properties in the martian magnetosheath based on MAVEN observations: A comparison of core and total ion populations}, volume = {990}, year = {2025}, }
• (2025). Learning the universe: Physically motivated priors for dust attenuation curves. ApJ, 990(2), 114. (www)

  @article{ , abstract = {Understanding the impact of dust on the spectral energy distributions (SEDs) of galaxies is crucial for inferring their physical properties and for studying the nature and evolution of interstellar dust. In this study, we analyze dust attenuation curves of ∼6400 galaxies ( M ⋆ ∼ 10 9 –10 11.5 M ⊙ ) at z = 0.07 from the IllustrisTNG50 & TNG100 simulations. Using radiative transfer post-processing, we generate synthetic attenuation curves and fit them with a versatile parametric model that encompasses both known extinction and attenuation curves (e.g., Calzetti, MW, SMC, and LMC) and more exotic forms. We present the distributions of the best-fitting parameters—UV slope ( c 1 ), optical-to-near-IR (NIR) slope ( c 2 ), far-UV (FUV) slope ( c 3 ), 2175 Å bump strength ( c 4 ), and normalization ( A V )—accounting for scatter from orientation effects. Key correlations emerge between A V and the star formation rate surface density Σ SFR , as well as the UV slope c 1 . Furthermore, the UV and FUV slopes ( c 1 , c 3 ) and the visual attenuation and bump strength ( A V , c 4 ) exhibit robust internal correlations (anticorrelation in the latter case). The optical-to-NIR slope exhibits minimal variations. Using these insights from simulations, we provide a set of scaling relations that predict a galaxy’s median (averaged over line of sight) dust attenuation curve based solely on its Σ SFR and/or A V . These predictions agree well with observed attenuation curves from the GALEX–Sloan Digital Sky Survey–Wide-field Infrared Survey Explorer Legacy Catalog, although there are minor differences in bump strength. This study delivers the most comprehensive library of synthetic attenuation curves for local galaxies, and provides a foundation for physically motivated priors for SED fitting and galaxy inference studies, such as those performed as part of the Learning the Universe Collaboration.}, archive = {J_ApJ}, author = {L. Sommovigo and R. K. Cochrane and R. S. Somerville and C. C. Hayward and C. C. Lovell and T. Starkenburg and G. Popping and K. Iyer and A. Gabrielpillai and M. Ho and U. P. Steinwandel and L. A. Perez}, doi = {10.3847/1538-4357/addec1}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {114}, shortjournal = {The Astrophys. J.}, title = {Learning the universe: Physically motivated priors for dust attenuation curves}, volume = {990}, year = {2025}, }
• (2025). OWLS. i. the olin wilson legacy survey. ApJ, 990(2), 113. (www)

  @article{ , abstract = {We present initial results from a planned 10 yr survey of Ca II H and K emission, using observations made with the Astrophysical Research Consortium 3.5 m Telescope at Apache Point Observatory. The primary goal of the survey is to investigate activity cycles in low-mass stars. The sample includes stars chosen from the legacy Mount Wilson Observatory (MWO) survey carried out by Olin Wilson more than 50 yr ago, together with newly identified planet-hosting stars and a select sample of early to mid M dwarfs. This paper presents the first 4 yr of data, comprising 1040 observations of 271 stars, with a specific focus on K and M stars. We identify a subsample of 153 stars for continuing observations over the full 10 yr survey. Early results indicate that our data are consistent with the MWO cycle periods over a time span of more than 50 yr; that there is a bifurcation in activity in the late K range with separate populations of low- and high-activity stars at lower masses; and that M dwarf planet hosts tend to be mainly found in the population of low-activity stars, even in the unbiased (by activity) TESS sample, potentially indicating a link between activity and planet formation. We have also found indications of possible cyclic variability in some of the lower-mass stars in the sample. Our ultimate goal is to link the activity cycle and rotation periods in a robust sample of stars spanning the FGKM spectral types and to investigate the implications for the underlying magnetic dynamo.}, archive = {J_ApJ}, author = {Brett M. Morris and Leslie Hebb and Suzanne L. Hawley and Kathryn Jones and Jake Romney}, doi = {10.3847/1538-4357/adeca5}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {113}, shortjournal = {The Astrophys. J.}, title = {OWLS. i. the olin wilson legacy survey}, volume = {990}, year = {2025}, }
• (2025). Massive interacting binaries enhance feedback in star-forming regions. ApJ, 990(2), 112. (www)

  @article{ , abstract = {We present a new framework to incorporate feedback from massive interacting binaries in simulations of star cluster formation. Our new feedback model adds binary stellar evolution to the cluster formation code Torch , and couples it in Amuse to the preexisting modules for collisional stellar dynamics, magnetohydrodynamics, and mechanical and radiative feedback. Our model accounts for the effects of mass transfer on the stars’ mass-loss rates, their radiation spectra, and the timing of core-collapse supernovae. It also injects mass lost through nonconservative mass transfer and CE ejection into the interstellar medium (ISM). We demonstrate the use of our feedback model through simulations of isolated binaries in a gaseous medium, and of embedded clusters of massive binaries. Feedback from interacting binaries efficiently couples with the surrounding ISM. It increases the size of H ii regions, increases the kinetic and thermal energy of the gas, and increases the pressure within H ii regions compared to models that use single star stellar evolution. Those differences arise from the ionizing radiation, which increases by 3 orders of magnitude, resulting in H ii regions that expand due to thermal pressure rather than radiation pressure. The effects of stellar dynamics and the gravitational potential of the background gas cause the evolution of individual binaries to deviate from the predictions made by secular evolution, impacting the subsequent feedback from the binary. We conclude that massive interacting binaries are an important source of feedback in cluster-forming regions, and must be considered when studying the emerging timescales of young star clusters.}, archive = {J_ApJ}, author = {Claude Cournoyer-Cloutier and Eric P. Andersson and Sabrina M. Appel and Natalia Lahén and Brooke Polak and Antti Rantala and Silvia Toonen and Alison Sills and Steven Rieder and Simon Portegies Zwart and Mordecai-Mark Mac Low and William E. Harris}, doi = {10.3847/1538-4357/adef01}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {112}, shortjournal = {The Astrophys. J.}, title = {Massive interacting binaries enhance feedback in star-forming regions}, volume = {990}, year = {2025}, }
• (2025). The interstellar medium in i zw 18 seen with JWST/MIRI. III. spatially resolved three ionization state oxygen abundance. ApJ, 990(2), 111. (www)

  @article{ , abstract = {We present observations of the nearby extremely metal-poor galaxy I Zw 18 using the Keck Cosmic Web Imager (KCWI) and the JWST Mid-InfraRed Instrument (MIRI) Integral Field Spectrographs. From optical and mid-IR oxygen emission lines, we measured direct-method abundances for three ionic states of oxygen, including O 3+ /H + . In contrast to previous studies of I Zw 18 the high spatial resolution afforded by KCWI and MIRI/MRS revealed chemical inhomogeneities on 60 pc scales in the form of metal-poor pockets and metal-enriched gas. These are located outside I Zw 18’s star-forming complexes having possibly been dispersed beyond these regions via stellar feedback effects. We found that metallicities derived using a single low-ionization density tracer, and T e ([O ii ]) derived from a temperature relationship commonly used in high- z galaxy studies, exhibited the largest scatter and underestimated the metallicity compared to those derived using multi-ion densities and estimated T e ([N ii ]). Finally, we compared O 3+ /H + abundances from a theoretical ionization correction factor (ICF) against observed values and found that the oxygen ICF underestimates the O 3+ /H + abundance by a factor of 2, indicating that either additional ionizing sources are needed or standard stellar population models are unable to produce the requisite ionizing flux.}, archive = {J_ApJ}, author = {Ryan J. Rickards Vaught and Leslie K. Hunt and Alessandra Aloisi and Maria Gabriela Navarro and Matilde Mingozzi and Bethan James and Macarena G. del Valle-Espinosa and Karin M. Sandstrom and Angela Adamo and Francesca Annibali and Daniela Calzetti and B. T. Draine and Svea Hernandez and Alec S. Hirschauer and Margaret Meixner and Dimitra Rigopoulou and Monica Tosi}, doi = {10.3847/1538-4357/adf10f}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {111}, shortjournal = {The Astrophys. J.}, title = {The interstellar medium in i zw 18 seen with JWST/MIRI. III. spatially resolved three ionization state oxygen abundance}, volume = {990}, year = {2025}, }
• (2025). Forward and reverse shock emission from relativistic jets with arbitrary angular and stratified radial profiles. ApJ, 990(2), 110. (www)

  @article{ , abstract = {Gamma-ray bursts are expected to be generated by structured jets, whose profiles significantly impact their afterglow emission. Previously, we developed a numerical code jetsimpy , to model the afterglow of jets with arbitrary angular profiles. In this study, we extend the code to incorporate a stratified radial profile, enabling it to model jets with arbitrary axisymmetric two-dimensional structures. The radial profile leads to the formation of a reverse shock. We modeled the shock system using an energy conservation prescription, which differs from the pressure balance approach. This leads to remarkably different predictions for reverse shock emission. In particular, we find that the reverse shock emission in the thin shell case is significantly overestimated in analytic models. We also explore the off-axis reverse shock emission from structured jets, where the cores belong to thick shell cases and the wings belong to thin shell cases. We have confirmed the prediction that off-axis observers may see a thin-to-thick transition, but we find that the light curve morphology is hard to distinguish from pure thin or thick shell cases. A radial profile also introduces hydrodynamic energy injection. As such, our code can naturally apply to refreshed shock cases, where the modeling of kilonova afterglows is demonstrated as an example. To validate our method, we fit the optical flash of GRB 990123, showing good agreement with the data. The upgraded jetsimpy provides unprecedented flexibility in modeling the afterglow emission of jets with various profiles, including those derived from general relativistic magnetohydrodynamic simulations.}, archive = {J_ApJ}, author = {Hao Wang and Hao Zhou and Yi-Zhong Fan and Da-Ming Wei}, doi = {10.3847/1538-4357/adf1a2}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {110}, shortjournal = {The Astrophys. J.}, title = {Forward and reverse shock emission from relativistic jets with arbitrary angular and stratified radial profiles}, volume = {990}, year = {2025}, }
• (2025). Minimum-entropy constraints on galactic potentials. ApJ, 990(2), 109. (www)

  @article{ , abstract = {A tracer sample in a gravitational potential, starting from a generic initial condition, phase-mixes toward a stationary state. This evolution is accompanied by an entropy increase, and the final state is characterized by a distribution function (DF) that depends only on integrals of motion (Jeans’ theorem). We present a method to constrain a gravitational potential assuming a stationary (phase mixed) sample by minimizing the entropy that the sample would have if it were allowed to phase-mix in trial potentials. This method avoids modeling the DF and is applicable to any sets of integrals. We provide expressions for the entropy of DFs depending on energy, f ( E ), energy and angular momentum, f ( E , L ), or three actions, f ( J ), and investigate the bias and statistical uncertainties in their estimates. We show that the method correctly recovers the parameters for spherical and axisymmetric potentials. We also present a methodology to characterize the posterior probability distribution of the parameters with an approximate Bayesian computation, indicating a pathway for application to observational data. Using 10 4 tracers with 10%(20%) uncertainties in the 6D coordinates, we recover the flattening parameter q of an axisymmetric potential with σ q / q ∼ 5%(10%). The python module for the entropy estimators, tropygal , is made publicly available.}, archive = {J_ApJ}, author = {Leandro Beraldo e Silva and Monica Valluri and Eugene Vasiliev and Kohei Hattori and Walter de Siqueira Pedra and Kathryne J. Daniel}, doi = {10.3847/1538-4357/adf1e3}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {109}, shortjournal = {The Astrophys. J.}, title = {Minimum-entropy constraints on galactic potentials}, volume = {990}, year = {2025}, }
• (2025). DELVE-DEEP survey: The faint satellite system of NGC 55. ApJ, 990(2), 108. (www)

  @article{ , abstract = {We report the first comprehensive census of the satellite dwarf galaxies around NGC 55 (2.1 Mpc) as a part of the DECam Local Volume Exploration DEEP (DELVE-DEEP) survey. NGC 55 is one of four isolated, Magellanic analogs in the Local Volume around which DELVE-DEEP aims to identify faint dwarfs and other substructures. We employ two complementary detection methods: one targets fully resolved dwarf galaxies by identifying them as stellar overdensities, while the other focuses on semiresolved dwarf galaxies, detecting them through shredded unresolved light components. As shown through extensive tests with injected galaxies, our search is sensitive to candidates down to M V ≲ −6.6 and surface brightness μ ≲ 28.5 mag arcsec 2 , and ∼80% complete down to M V ≲ −7.8. We do not report any new confirmed satellites beyond two previously known systems, ESO 294–010 and NGC 55-dw1. We construct the satellite luminosity function of NGC 55 and find it to be consistent with the predictions from cosmological simulations. As one of the first complete luminosity functions for a Magellanic analog, our results provide a glimpse of the constraints on low-mass-host satellite populations that will be further explored by upcoming surveys, such as the Vera C. Rubin Observatory’s Legacy Survey of Space and Time.}, archive = {J_ApJ}, author = {Jonah Medoff and Burçin Mutlu-Pakdil and Jeffrey L. Carlin and Alex Drlica-Wagner and Erik J. Tollerud and Amandine Doliva-Dolinsky and David J. Sand and Clara E. Martínez-Vázquez and Guy S. Stringfellow and William Cerny and Denija Crnojević and Peter S. Ferguson and Catherine E. Fielder and Astha Chaturvedi and Nitya Kallivayalil and Noelia E. D. Noël and Kathy Vivas and Alistair R. Walker and Monika Adamów and Clecio R. Bom and Julio A. Carballo-Bello and Yumi Choi and Gustavo E. Medina and Mahdieh Navabi and Andrew B. Pace and Alex H. Riley and Joanna D. Sakowska}, doi = {10.3847/1538-4357/adf211}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {108}, shortjournal = {The Astrophys. J.}, title = {DELVE-DEEP survey: The faint satellite system of NGC 55}, volume = {990}, year = {2025}, }
• (2025). Orbital and physical properties of the pleiades binary 27 tau (Atlas). ApJ, 990(2), 107. (www)

  @article{ , abstract = {We report new spectroscopic and interferometric observations of the Pleiades binary star Atlas, which played an important role nearly 3 decades ago in settling the debate over the distance to the cluster from ground-based and space-based determinations. We use the new measurements, together with other published and archival astrometric observations, to improve the determination of the 291 day orbit and the distance to Atlas (136.2 ± 1.4 pc). We also derive the main properties of the components, including their absolute masses (5.04 ± 0.17 M ⊙ and 3.64 ± 0.12 M ⊙ ), sizes, effective temperatures, projected rotational velocities, and chemical compositions. We find that the more evolved primary star is rotationally distorted, and we are able to estimate its oblateness and the approximate orientation of its spin axis from the interferometric observations. The spin axis may well be aligned with the orbital axis. Models of stellar evolution from the Modules for Experiments in Stellar Astrophysics (or MESA) that account for rotation provide a good match to all of the primary’s global properties, and point to an initial angular rotation rate on the zero-age main sequence of about 55% of the breakup velocity. The current location of the star in the Hertzsprung–Russell diagram is near the very end of the hydrogen-burning main sequence, at an age of about 105 Myr, according to these models. Our spectroscopic analysis of the more slowly rotating secondary indicates that it is a helium-weak star, with other chemical anomalies.}, archive = {J_ApJ}, author = {Guillermo Torres and Andrew Tkachenko and Krešimir Pavlovski and Seth Gossage and Gail H. Schaefer and Carl Melis and Michael Ireland and John D. Monnier and Narsireddy Anugu and Stefan Kraus and Cyprien Lanthermann and Kathryn Gordon and Robert Klement and Simon J. Murphy and Rachael M. Roettenbacher}, doi = {10.3847/1538-4357/adf224}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {107}, shortjournal = {The Astrophys. J.}, title = {Orbital and physical properties of the pleiades binary 27 tau (Atlas)}, volume = {990}, year = {2025}, }
• (2025). Assessing robustness and bias in 1D retrievals of 3D global circulation models at high spectral resolution: A WASP-76 b simulation case study in emission. ApJ, 990(2), 106. (www)

  @article{ , abstract = {High-resolution spectroscopy (HRS) of exoplanet atmospheres has successfully detected many chemical species and is quickly moving toward detailed characterization of the chemical abundances and dynamics. HRS is highly sensitive to the line shape and position; thus, it can detect three-dimensional (3D) effects such as winds, rotation, and spatial variation of atmospheric conditions. At the same time, retrieval frameworks are increasingly deployed to constrain chemical abundances, pressure–temperature ( P – T ) structures, orbital parameters, and rotational broadening. To explore the multidimensional parameter space, we need computationally fast models, which are consequently mostly one-dimensional (1D). However, this approach risks introducing interpretation bias since the planet’s true nature is 3D. We investigate the robustness of this methodology at high spectral resolution by running 1D retrievals on simulated observations in emission within an observational framework using 3D global circulation models of the quintessential HJ WASP-76 b. We find that the retrieval broadly recovers conditions present in the atmosphere, but that the retrieved P – T and chemical profiles are not a homogeneous average of all spatial and phase-dependent information. Instead, they are most sensitive to spatial regions with large thermal gradients, which do not necessarily coincide with the strongest emitting regions. Our results further suggest that the choice of parameterization for the P – T and chemical profiles, as well as Doppler offsets among opacity sources, impact the retrieval results. These factors should be carefully considered in future retrieval analyses.}, archive = {J_ApJ}, author = {Lennart van Sluijs and Hayley Beltz and Isaac Malsky and Genevieve H. Pereira and L. Cinque and Emily Rauscher and Jayne Birkby}, doi = {10.3847/1538-4357/adf328}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {106}, shortjournal = {The Astrophys. J.}, title = {Assessing robustness and bias in 1D retrievals of 3D global circulation models at high spectral resolution: A WASP-76 b simulation case study in emission}, volume = {990}, year = {2025}, }
• (2025). Deep neural networks for modeling astrophysical nuclear reacting flows. ApJ, 990(2), 105. (www)

  @article{ , abstract = {In astrophysical simulations, nuclear reacting flows pose computational challenges due to the stiffness of reaction networks. We introduce neural network-based surrogate models using the DeePODE framework to enhance simulation efficiency while maintaining accuracy and robustness. Our method replaces conventional stiff ordinary differential equation (ODE) solvers with deep learning models trained through evolutionary Monte Carlo sampling from zero-dimensional simulation data, ensuring generalization across varied thermonuclear and hydrodynamic conditions. Tested on 3-species and 13-species reaction networks, the models achieve ≲1% accuracy relative to semi-implicit numerical solutions and deliver a ∼2.6× speedup on CPUs. A temperature-thresholded deployment strategy ensures stability in extreme conditions, sustaining neural network utilization above 75% in multidimensional simulations. These data-driven surrogates effectively mitigate stiffness constraints, offering a scalable approach for high-fidelity modeling of astrophysical nuclear reacting flows.}, archive = {J_ApJ}, author = {Xiaoyu Zhang and Yuxiao Yi and Lile Wang and Zhi-Qin John Xu and Tianhan Zhang and Yao Zhou}, doi = {10.3847/1538-4357/adf331}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {105}, shortjournal = {The Astrophys. J.}, title = {Deep neural networks for modeling astrophysical nuclear reacting flows}, volume = {990}, year = {2025}, }
• (2025). Predicting the properties of the fallback rate from tidal disruption events: Investigating the maximum gravity model. ApJ, 990(2), 104. (www)

  @article{ , abstract = {A star destroyed by the tidal field of a supermassive black hole (SMBH) in a tidal disruption event (TDE) gives rise to a luminous flare. TDEs are being detected at an ever-increasing rate, motivating the need for accurate models of their lightcurves. The “maximum gravity” (MG) model posits that a star is completely destroyed when the tidal field of the SMBH exceeds the maximum self-gravitational field within the star, {g}_{{{\rm{\max }}}} , and predicts the peak fallback rate {\dot{M}}_{{{\rm{peak}}}} and the time to peak t peak . Here we perform hydrodynamical simulations of the complete disruption of 24 stars with masses ranging from 0.2 to 5.0 M ⊙ , at different stages of their main sequence evolution, to test the predictions of this model. We find excellent agreement between the MG model predictions and our simulations for stars near the zero-age main sequence, while the predictions are less accurate (but still within ∼35%–50% of the simulation results) for highly evolved stars. We also generalize the MG model to incorporate the Paczyński–Wiita potential to assess the impact of strong-gravity effects, which are especially important for deep encounters that are required to completely destroy evolved and centrally concentrated stars, and find good agreement with recent works that include relativistic gravity. Our results demonstrate that this model provides accurate constraints on the peak timescale of TDE lightcurves and their correlation with black hole mass.}, archive = {J_ApJ}, author = {Julia Fancher and Ananya Bandopadhyay and Eric R. Coughlin and C. J. Nixon}, doi = {10.3847/1538-4357/adf33c}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {104}, shortjournal = {The Astrophys. J.}, title = {Predicting the properties of the fallback rate from tidal disruption events: Investigating the maximum gravity model}, volume = {990}, year = {2025}, }
• (2025). Inhomogeneous stellar mixing in the final hours before the cassiopeia a supernova. ApJ, 990(2), 103. (www)

  @article{ , abstract = {Understanding stars and their evolution is a key goal of astronomical research and has long been a focus of human interest. In recent years, theorists have paid much attention to the final interior processes within massive stars, as they can be essential for revealing neutrino-driven supernova mechanisms and other potential transients of massive star collapse. However, it is challenging to observe directly the last hours of a massive star before explosion, since it is the supernova event that triggers the start of intense observational study. Here, we report evidence for a final phase of stellar activity known as a “shell merger,” an intense shell burning in which the O-burning shell swallows its outer C-/Ne-burning shell, deep within the progenitor’s interior moments before the supernova explosion. In the violent convective layer created by the shell merger, Ne, which is abundant in the stellar O-rich layer, is burned as it is pulled inward, and Si, which is synthesized inside, is transported outward. The remnant still preserves some traces of such Ne-rich downflows and Si-rich upflows in the O-rich layer, suggesting that inhomogeneous shell-merger mixing began just hours (≲10 4 s) before its gravitational collapse. Our results provide the first observational evidence that the final stellar burning process rapidly alters the internal structure, leaving a pre-supernova asymmetry. This breaking of spherical symmetry facilitates the explosion of massive stars and influences various supernova and remnant characteristics, including explosion asymmetries and the neutron star’s kick and spin.}, archive = {J_ApJ}, author = {Toshiki Sato and Kai Matsunaga and Hiroyuki Uchida and Satoru Katsuda and Koh Takahashi and Hideyuki Umeda and Tomoya Takiwaki and Ryo Sawada and Takashi Yoshida and Ko Nakamura and Yui Kuboike and Paul P. Plucinsky and John P. Hughes}, doi = {10.3847/1538-4357/aded14}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {103}, shortjournal = {The Astrophys. J.}, title = {Inhomogeneous stellar mixing in the final hours before the cassiopeia a supernova}, volume = {990}, year = {2025}, }
• (2025). Extended star formation in luminous infrared galaxies at z ∼ 1 in the SMILES field. ApJ, 990(2), 102. (www)

  @article{ , abstract = {Luminous infrared galaxies (LIRGs) and ultraluminous infrared galaxies (ULIRGs) in the local Universe are highly centrally concentrated in the mid-infrared (MIR) and substantially more likely than non-(U)LIRGs to be involved in mergers. At higher redshifts, images of radio emission, cold dust, and molecular gas have suggested that (U)LIRGs at cosmic noon and even earlier may be relatively less concentrated than their z ∼ 0 counterparts. Prior to the launch of the James Webb Space Telescope (JWST), quantifying the extent of obscured star formation in (U)LIRGs at z ∼ 1 was not possible due to the low spatial resolution of previous instruments in the MIR. With JWST’s Mid-Infrared Instrument (MIRI), it is now possible. We use MIRI imaging to identify a sample of 24 LIRGs at 0.5 ≤ z ≤ 1.22 in the Systematic Mid-Infrared Legacy Extragalactic Survey and find that they are generally less centrally concentrated than their z ∼ 0 counterparts. Compared to high-mass star-forming galaxies that are not LIRGs, we find little evidence that LIRGs are more likely to be morphologically disturbed at rest-frame UV, optical, and near-infrared wavelengths at z ∼ 1. This also differs from the local counterparts where strong disturbances and major mergers are closely associated with LIRGs. These results support suggestions that smaller disturbances and perhaps even internal processes can trigger the collapse of gas clouds outside of galactic cores and cause very high levels of extended star formation at z ≳ 1.}, archive = {J_ApJ}, author = {Michael K. Florian and George H. Rieke and Stacey Alberts and Irene Shivaei and Jakob M. Helton and Jianwei Lyu and Kevin N. Hainline and Zhiyuan Ji}, doi = {10.3847/1538-4357/adee1d}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {102}, shortjournal = {The Astrophys. J.}, title = {Extended star formation in luminous infrared galaxies at z ∼ 1 in the SMILES field}, volume = {990}, year = {2025}, }
• (2025). Solar flares as electron accelerators: Toward a resolution of the acceleration efficiency issue. ApJ, 990(2), 101. (www)

  @article{ , abstract = {A major open issue concerning the active Sun is the effectiveness with which magnetic reconnection accelerates electrons in flares. A paper published by Nature in 2022 used microwave observations to conclude that the Sun is an almost ideal accelerator, energizing nearly all electrons within a coronal volume to nonthermal energies. Shortly thereafter, a paper published in Astrophysical Journal Letters used hard X-ray measurements of the same event to reach the contradictory conclusion that less than 1% of the available electrons were accelerated. Here we address this controversy by using spatially resolved observations of hard X-ray emission and a spectral inversion method to determine the evolution of the electron spectrum throughout a set of flares. We use the spatial variation of the electron spectrum to deduce the density of the medium where electrons propagate and, from this and the total intensity of the flare, the ratio of accelerated to ambient electron densities. Results show that this ratio never exceeds 1% or so in all the events analyzed.}, archive = {J_ApJ}, author = {Anna Volpara and Paolo Massa and Michele Piana and Anna Maria Massone and A. Gordon Emslie}, doi = {10.3847/1538-4357/adee25}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {101}, shortjournal = {The Astrophys. J.}, title = {Solar flares as electron accelerators: Toward a resolution of the acceleration efficiency issue}, volume = {990}, year = {2025}, }
• (2025). Plasma instability in front of ejected energetic electrons and type III solar radio bursts. ApJ, 990(2), 100. (www)

  @article{ , abstract = {Type III radio bursts are signatures of the fluxes of near-relativistic electrons ejected during solar flares. These bursts are frequently observed by spacecraft such as the Parker Solar Probe. It has been traditionally believed that these electron beams generate Langmuir waves through the two-stream instability, which are then converted into electromagnetic waves. In this study, we revise that model, by examining how the electron distribution becomes truncated due to the “time-of-flight” effect, as the beam travels through a randomly inhomogeneous and gently varying solar wind plasma. Rather than the two-stream instability, this truncation destabilizes the distribution and leads to the generation of Langmuir waves via a linear instability; we confine our analysis to this linear regime and do not take into account the backreaction of the generated Langmuir waves on the electron distribution, which is nonlinear. The instability grows until slower electrons arrive and dampen the waves. Our qualitative analysis shows that the resulting wave intensity growth and decay closely match the intensity–time profile of observed type III radio bursts at the fundamental frequency, supporting this modified theory.}, archive = {J_ApJ}, author = {Vladimir Krasnoselskikh and Immanuel Christopher Jebaraj and Tom Robert Franck Cooper and Andrii Voschepynets and Thierry Dudok de Wit and Marc Pulupa and Forrest Mozer and Oleksiy Agapitov and Michael Balikhin and Stuart D. Bale}, doi = {10.3847/1538-4357/adf281}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {100}, shortjournal = {The Astrophys. J.}, title = {Plasma instability in front of ejected energetic electrons and type III solar radio bursts}, volume = {990}, year = {2025}, }
• (2025). A parameter-masked mock data challenge for beyond-two-point galaxy clustering statistics*. ApJ, 990(2), 99. (www)

  @article{ , abstract = {The past few years have seen the emergence of a wide array of novel techniques for analyzing high-precision data from upcoming galaxy surveys, which aim to extend the statistical analysis of galaxy clustering data beyond the linear regime and the canonical two-point (2pt) statistics. We test and benchmark some of these new techniques in a community data challenge named “Beyond-2pt,” initiated during the Aspen 2022 Summer Program “Large-Scale Structure Cosmology beyond 2-Point Statistics,” whose first round of results we present here. The challenge data set consists of high-precision mock galaxy catalogs for clustering in real space, in redshift space, and on a light cone. Participants in the challenge have developed end-to-end pipelines to analyze mock catalogs and extract unknown (“masked”) cosmological parameters of the underlying ΛCDM models with their methods. The methods represented are density-split clustering, nearest neighbor statistics, BACCO power spectrum emulator, void statistics, LEFTfield field-level inference using effective field theory (EFT), and joint power spectrum and bispectrum analyses using both EFT and simulation-based inference. In this work, we review the results of the challenge, focusing on problems solved, lessons learned, and future research needed to perfect the emerging beyond-2pt approaches. The unbiased parameter recovery demonstrated in this challenge by multiple statistics and the associated modeling and inference frameworks supports the credibility of cosmology constraints from these methods. The challenge data set is publicly available, and we welcome future submissions from methods that are not yet represented.}, archive = {J_ApJ}, author = {The Beyond-2pt Collaboration and Elisabeth Krause and Yosuke Kobayashi and Andrés N. Salcedo and Mikhail M. Ivanov and Tom Abel and Kazuyuki Akitsu and Raul E. Angulo and Giovanni Cabass and Sofia Contarini and Carolina Cuesta-Lazaro and ChangHoon Hahn and Nico Hamaus and Donghui Jeong and Chirag Modi and Nhat-Minh Nguyen and Takahiro Nishimichi and Enrique Paillas and Marcos Pellejero Ibañez and Oliver H. E. Philcox and Alice Pisani and Fabian Schmidt and Satoshi Tanaka and Giovanni Verza and Sihan Yuan and Matteo Zennaro}, doi = {10.3847/1538-4357/ad781d}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {99}, shortjournal = {The Astrophys. J.}, title = {A parameter-masked mock data challenge for beyond-two-point galaxy clustering statistics*}, volume = {990}, year = {2025}, }
• (2025). Mass and metal flows in isolated IllustrisTNG halos. ApJ, 990(2), 98. (www)

  @article{ , abstract = {The circumgalactic medium (CGM) is a reservoir of metals and star-forming fuel. Most baryons in the Universe are in the CGM or the intergalactic medium (IGM). The baryon cycle—how mass and metals reach the CGM from the inner regions of the galaxy and how gas from the CGM replenishes star-forming activity in the inner regions—is an essential question in galaxy evolution. In this paper, we study the flow of mass and metals in a stacked sample of 2770 isolated halos from the IllustrisTNG100 cosmological hydrodynamic simulation. The mean gas flow as a function of radius and angle is similar across a large galactic mass range when accounting for different feedback modes. Although both star formation and black holes cause powerful outflows, the flows from star formation are more angularly restricted. Black hole feedback dominates mass flow throughout the halo, while star formation feedback mainly affects the inner region. When scaling by virial radius ( R v ), large dynamical changes occur at 0.2 R v for most halos, suggesting a characteristic size for the inner galaxy. Despite kinetic-mode feedback from black holes being the primary quenching mechanism in IllustrisTNG, a small population of high-mass kinetic-mode disks are able to form stars.}, archive = {J_ApJ}, author = {Jacob Morgan and Jeremy Bailin and Annelia Anderson}, doi = {10.3847/1538-4357/addf46}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {98}, shortjournal = {The Astrophys. J.}, title = {Mass and metal flows in isolated IllustrisTNG halos}, volume = {990}, year = {2025}, }
• (2025). Connecting solar orbiter and l1 measurements of mesoscale solar wind structures to their coronal source using the ADAPT-WSA model. ApJ, 990(2), 97. (www)

  @article{ , abstract = {Much of the dynamics of the ambient solar wind (SW) manifests at mesoscales—scales larger than kinetic but smaller than global structures. Mesoscale structures often form at the Sun, survive to 1 au, and are geoeffective. Identifying their origins, release, and acceleration mechanisms is critical to advancing heliophysics. We investigate a 6 day interval (2022 March 4 00:00:00 UT–2022 March 9 23:59:59 UT) in which Solar Orbiter (SO) was radially aligned with Earth. We characterize mesoscale structures observed in SO Heavy Ion Sensor (HIS) Fe/O and O 7+ /O 6+ in situ measurements, and confirm their survival to L1. A subset of these structures are periodic, suggesting that they formed at the Sun. We use the ADAPT-WSA model to connect in situ measurements to their remotely observed sources at the Sun. We characterize the SW sources using model-determined proxies for SW formation (e.g., the S-web). We compare Fe/O observed at SO/HIS, with S/O abundances derived by the Spectral Imaging of the Coronal Environment (SO/SPICE), at the WSA-determined SW sources. We find (1) SO and ACE/Wind observe similar many-hour structures, linking mesoscale structures from their source to two well-separated locations in situ for the first time. (2) Observed periodicities are consistent with those observed in prior studies of mesoscale structures throughout the inner heliosphere. (3) SW originating from only one of the four SPICE rasters can be interpreted as plasma originating from open fields. The SW from the other three require a different interpretation, and we suggest interchange reconnection as the most natural solution.}, archive = {J_ApJ}, author = {Samantha Wallace and Natalia Zambrana Prado and Irena Gershkovich and Nicholeen M. Viall and Peter Young and Therese A. Kucera and Susan T. Lepri and Stephanie L. Yardley and Jim M. Raines and Stefano A. Livi and Ryan M. Dewey}, doi = {10.3847/1538-4357/adec6c}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {97}, shortjournal = {The Astrophys. J.}, title = {Connecting solar orbiter and l1 measurements of mesoscale solar wind structures to their coronal source using the ADAPT-WSA model}, volume = {990}, year = {2025}, }
• (2025). Tracing the formation history of intrahalo light with horizon run 5. ApJ, 990(2), 96. (www)

  @article{ , abstract = {We investigate the formation history of intrahalo light (IHL) using the high-resolution (∼1 kpc), large-scale (∼1 Gpc) cosmological hydrodynamical simulation Horizon Run 5 (HR5). IHL particles are identified by carefully considering both their binding energies and positions with respect to the tidal radii of individual galaxies. By analyzing more than 1200 galaxy groups and clusters with ≳10 13 M ⊙ and tracing their individual IHL particles back in time, we classify the origin of each IHL particle at each epoch, based on the status of the originating galaxy, into one of three categories: brightest halo galaxy (BHG) formation/merger, satellite galaxy stripping, and preprocessing. Our study reveals that IHL production through BHG formation/merger is the predominant production channel, contributing over 60% of the total IHL mass across all redshifts. The second most significant IHL production channel is preprocessing, providing more than 20% in the final HR5 snapshot. Stripping is negligible at z > 4 but becomes gradually more important as the halos mature at z < 4. Finally, we verify that the IHL production through the disruption of dwarf galaxies and in situ formation is negligible, contributing less than ∼3% and ∼0.5% to the total IHL production, respectively.}, archive = {J_ApJ}, author = {Hyungjin Joo and M. James Jee and Juhan Kim and Jaehyun Lee and Jongwan Ko and Changbom Park and Jihye Shin and Owain Snaith and Christophe Pichon and Brad Gibson and Yonghwi Kim}, doi = {10.3847/1538-4357/adf4d0}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {96}, shortjournal = {The Astrophys. J.}, title = {Tracing the formation history of intrahalo light with horizon run 5}, volume = {990}, year = {2025}, }
• (2025). Development of 1D non-ideal MHD simulation code towards understanding long-term evolution of protoplanetary disk. ApJ, 990(2), 95. (www)

  @article{ , abstract = {We developed a one-dimensional magnetohydrodynamic (MHD) simulation code to investigate the long-term evolution of protoplanetary disks with low computational cost. In this simulation code, the physical processes necessary for protostellar formation and protoplanetary disk evolution, such as magnetic braking, nonideal MHD effects, and angular momentum transport due to viscosity, are implemented. Using this simulation code, we performed the simulations of the long-term evolution of protoplanetary disks starting from the molecular cloud. Our simulation results suggest that the disk size and mass are a few tens of astronomical units and ∼0.01 M ⊙ at 10 5 yr after protostellar formation. These values were relatively consistent with observations. The disk evolves through magnetic braking, and its radial profiles are consistent with the analytical solutions of previous studies. Our simulation code will be an important tool for studying the long-term evolution of protoplanetary disks.}, archive = {J_ApJ}, author = {Yudai Kobayashi and Daisuke Takaishi and Yusuke Tsukamoto and Shantanu Basu}, doi = {10.3847/1538-4357/adf4ea}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {95}, shortjournal = {The Astrophys. J.}, title = {Development of 1D non-ideal MHD simulation code towards understanding long-term evolution of protoplanetary disk}, volume = {990}, year = {2025}, }
• (2025). The X-ray link between high eddington ratio dust-obscured galaxies (DOGs) and hot DOGs. ApJ, 990(2), 94. (www)

  @article{ , abstract = {Dust-obscured galaxies (DOGs) with extremely red optical-to-infrared colors are often associated with intense starburst and active galactic nucleus (AGN) activity. Studying DOGs can provide insights into the processes that drive the growth of galaxies and their central supermassive black holes. However, the general DOG population is heterogeneous, spanning a wide range of evolutionary stages, and has X-ray obscuring column densities ( N H ) covering low to high levels. In this work, we focus on seven high Eddington ratio DOGs ( {\mathrm{log}}{\lambda }_{{\rm{Edd}}}\gtrsim -0.5 ) to examine their X-ray obscuration properties using new and archival X-ray observations. We confirm that these systems are generally heavily obscured, with six out of seven having N H ≳ 10 23 cm −2 and three out of seven having N H ≳ 10 24 cm −2 . Based on the observed similarity with the rare Hot DOG population, we argue that both high- λ Edd DOGs and Hot DOGs likely trace the postmerger phase, during which AGNs are enshrouded by large columns of dust-rich material.}, archive = {J_ApJ}, author = {Fan Zou and W. N. Brandt and Elena Gallo and Fabio Vito and Zhibo Yu}, doi = {10.3847/1538-4357/adf55c}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {94}, shortjournal = {The Astrophys. J.}, title = {The X-ray link between high eddington ratio dust-obscured galaxies (DOGs) and hot DOGs}, volume = {990}, year = {2025}, }
• (2025). A target search for fast radio bursts associated with two fast blue optical transients: AT2018cow and CSS161010. ApJ, 990(2), 93. (www)

  @article{ , abstract = {Fast blue optical transients (FBOTs) are luminous, rapidly evolving events with blue spectra, possibly powered by newborn magnetars and linked to fast radio bursts (FRBs). Given this potential connection, we conducted deep radio observations of two nearby FBOTs (AT2018cow and CSS161010) using the Five-hundred-meter Aperture Spherical radio Telescope, but detected no FRB-like signals. Our observations establish the most stringent upper limits on millisecond radio transients from FBOTs, reaching ∼10 mJy flux density. Assuming a log-normal luminosity function analogous to the repeating FRB 121102, we constrain the burst rate from potential magnetars in FBOTs to < 0.01 hr −1 . The short ejecta escape timescale (∼2.6 yr) compared to our observation epochs (4−6 yr post-explosion) suggests that nondetection may not be attributed to FBOT’s ejecta absorption. These findings impose useful constraints on the FRB activity emanating from newborn magnetars within FBOTs. They indicate that if there is a burst phase, it is either characterized by weaker bursts, occurs less frequently compared to those in known repeating FRB sources, or takes place beyond the time frame of our current observations. To gain deeper insights into the birth-related activity of magnetars, it is of importance to conduct timely and sustained FRB searches in FBOTs that emerge in the future.}, archive = {J_ApJ}, author = {Shi-Jie Gao and Xiang-Dong Li and Yi-Xuan Shao and Ping Zhou and Pei Wang and Yun-Wei Yu and Zhen Yan and Di Li}, doi = {10.3847/1538-4357/adf732}, journal = {The Astrophysical Journal}, month = {9}, number = {2}, pages = {93}, shortjournal = {The Astrophys. J.}, title = {A target search for fast radio bursts associated with two fast blue optical transients: AT2018cow and CSS161010}, volume = {990}, year = {2025}, }
• (2025). Erratum: “Low-metallicity nova explosions: A site for weak rp-process nucleosynthesis” (2025, ApJ, 987, 88). ApJ, 990(1), 92. (www)

  @article{ , archive = {J_ApJ}, author = {Athanasios Psaltis and Jordi José and Richard Longland and Christian Iliadis}, doi = {10.3847/1538-4357/adf854}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {92}, shortjournal = {The Astrophys. J.}, title = {Erratum: “Low-metallicity nova explosions: A site for weak rp-process nucleosynthesis” (2025, ApJ, 987, 88)}, volume = {990}, year = {2025}, }
• (2025). Transient blurring of the scintillation arc of pulsar b1737+13. ApJ, 990(1), 91. (www)

  @article{ , abstract = {For many pulsars, the scattering structures responsible for scintillation are typically dominated by a single, thin screen along the line of sight, which persists for years or decades. In recent years, an increasing number of doubly lensed events have been observed, where a secondary lens crosses the line of sight. This causes additional or distorted scintillation arcs over timescales ranging from days to months. In this work, we report such a transient event for pulsar B1737+13 and propose a possible lensing geometry including the distance to both lenses and the orientation of the main screen. Using phase retrieval techniques to separate the two lenses in the wavefield, we report the curvature and rate of motion of features associated with the secondary lens as it passed through the line of sight. By fitting the annual variation of the curvature, we report a possible distance and orientation for the main screen. The distance of the secondary lens is found by mapping the secondary feature onto the sky and tracking its position over time for different distances. We validate this method using B0834+06, for which the screen solutions are known through VLBI, and successfully recover the correct solution for the secondary feature. With the identified lensing geometry, we are able to estimate the size of the secondary lens, 1–3 au. Although this is an appropriate size for a structure that could cause an extreme scattering event, we do not have conclusive evidence for or against that possibility.}, archive = {J_ApJ}, author = {Yen-Hua Chen and Sammy Siegel and Daniel Baker and Ue-Li Pen and Dan Stinebring}, doi = {10.3847/1538-4357/ade4c0}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {91}, shortjournal = {The Astrophys. J.}, title = {Transient blurring of the scintillation arc of pulsar b1737+13}, volume = {990}, year = {2025}, }
• (2025). Chandra X-ray observatory study of the X-ray emission of PKS 0023−26 and comparison with recent ALMA results. ApJ, 990(1), 90. (www)

  @article{ , abstract = {We present a deep high-resolution Chandra X-ray Observatory study of the powerful compact radio source PKS 0023−26 associated with a quasar at redshift 0.322. Earlier studies of the optical environment suggested that the source could be located in a galaxy cluster or a group. However, we report a nondetection of hot gas on large scales (out to ∼60 kpc radius) and place an upper limit on the X-ray luminosity of <3 × 10 42 erg s −1 , consistent only with the presence of a poor, low-temperature ( kT < 0.5 keV) galaxy group. X-ray spectral analysis of the central circular region, r < 7 kpc, shows, in addition to the mildly absorbed active galactic nucleus, a thermal emission component with a temperature of kT=0.{9}_{-0.37}^{+0.19} keV. We discuss the origin of this hot component as a result of interaction between the evolving radio source and the interstellar medium (ISM). Our high-angular-resolution X-ray image traces the distribution of hot gas, which is closely aligned with and extends beyond the radio source, and also in the direction perpendicular to the axis of the radio source. The X-rays are enhanced in the northern radio lobe and at the location of the peak of the CO(3–2)/CO(2–1) line emission, suggesting that the interactions between the jet and cold medium result in the X-ray radiation that excites CO. The shock driven by the jet into the ISM is supersonic with a Mach number of { \mathcal M }\sim 1.75 –2, creating the cocoon of hot X-rays that surrounds the radio source. This result agrees with observations of shocks in other radio galaxies and points to the prevalent impact of jets on the ISM.}, archive = {J_ApJ}, author = {A. Siemiginowska and R. Morganti and G. Fabbiano and E. O’Sullivan and T. Oosterloo and C. Tadhunter and D. Burke}, doi = {10.3847/1538-4357/adf19f}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {90}, shortjournal = {The Astrophys. J.}, title = {Chandra X-ray observatory study of the X-ray emission of PKS 0023−26 and comparison with recent ALMA results}, volume = {990}, year = {2025}, }
• (2025). First X-ray polarimetric view of a low-luminosity active galactic nucleus: The case of NGC 2110. ApJ, 990(1), 89. (www)

  @article{ , abstract = {Low-luminosity active galactic nuclei (LLAGN) provide a unique view of Comptonization and nonthermal emission from accreting black holes in the low accretion rate regime. However, to decipher the exact nature of the Comptonizing corona in LLAGN, its geometry and emission mechanism must be understood beyond the limits of spectro-timing techniques. Spectropolarimetry offers the potential to break the degeneracies between different coronal emission models. Compton-thin LLAGN provide an opportunity for such spectropolarimetric exploration in the 2–8 keV energy range using the Imaging X-Ray Polarimetry Explorer (IXPE). In this work, we carry out a spectropolarimetric analysis of the first IXPE observation, in synergy with a contemporaneous Nuclear Spectroscopic Telescope Array observation, of an LLAGN: NGC 2110. Using 554.4 ks of IXPE data from 2024 October, we constrain the 99% upper limit on the polarization degree (PD) to be less than 8.3% assuming the corresponding polarization angle (PA) to be aligned with the radio jet, and less than 3.6% if in the perpendicular direction. In the absence of a significant PD detection, the PA remains formally unconstrained, yet the polarization significance contours appear to be aligned with the radio jet, tentatively supporting models in which the corona is radially extended in the plane of the disk. We also carry out detailed Monte Carlo simulations using monk and STOKES codes to test different coronal models against our results and compare the polarization properties between NGC 2110 and brighter Seyferts.}, archive = {J_ApJ}, author = {Sudip Chakraborty and Ajay Ratheesh and Daniele Tagliacozzo and Philip Kaaret and Jakub Podgorný and Frédéric Marin and Francesco Tombesi and Steven R. Ehlert and Chien-Ting J. Chen and Dawoon E. Kim and Ioannis Liodakis and Francesco Ursini and Riccardo Middei and Alessandro Di Marco and Fabio La Monaca and Srimanta Banerjee and Keigo Fukumura and W. Peter Maksym and Romana Mikušincová and Rodrigo Nemmen and Pierre-Olivier Petrucci and Paolo Soffitta and Jiří Svoboda and Wenda Zhang}, doi = {10.3847/1538-4357/ade87d}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {89}, shortjournal = {The Astrophys. J.}, title = {First X-ray polarimetric view of a low-luminosity active galactic nucleus: The case of NGC 2110}, volume = {990}, year = {2025}, }
• (2025). Counting mass with gaia: Mass density of stars and stellar remnants in the solar neighborhood. ApJ, 990(1), 88. (www)

  @article{ , abstract = {In the light of new full-sky surveys, many attempts to create a consistent Galactic model were made. The main interest is to estimate the still poorly understood dark matter content. However, the results vary depending on methodology, assumptions, and baryonic distribution used. To understand this discrepancy, we take the first step by estimating the model-free local mass density of stars and stellar remnants. We use a complete sample from the Gaia Catalogue of Nearby Stars within 100 pc from the Sun, together with the data on the sample of the white dwarfs and the recent estimate of the neutron star concentration in the solar neighborhood. After correction for unresolved binary stars and accounting for missing low-mass stars, we find that the local mass density of stars and stellar remnants in the solar neighborhood is {\rho }_{100}=0.04{0}_{-0.006}^{+0.012}\,{M}_{\odot \,}{{\mathrm{pc}}}^{-3} with a Kroupa initial mass function (IMF) and {\rho }_{100}=0.03{7}_{-0.006}^{+0.012}\,{M}_{\odot \,}{{\mathrm{pc}}}^{-3} with a Chabrier IMF.}, archive = {J_ApJ}, author = {Artem Lutsenko and Giovanni Carraro and Vladimir Korchagin and Roman Tkachenko and Katherine Vieira}, doi = {10.3847/1538-4357/adec66}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {88}, shortjournal = {The Astrophys. J.}, title = {Counting mass with gaia: Mass density of stars and stellar remnants in the solar neighborhood}, volume = {990}, year = {2025}, }
• (2025). Quasiperiodic variation during a fast X-ray outburst of a high-mass X-ray binary MAXI j0709-159/LY CMa observed by NICER. ApJ, 990(1), 87. (www)

  @article{ , abstract = {We report on a quasiperiodic variation at ∼1 Hz during a fast X-ray outburst of a high-mass X-ray binary MAXI J0709−159/LY CMa observed by the Neutron star Interior Composition ExploreR (NICER). The new X-ray transient MAXI J0709−159 was discovered on 2022 January 25. Due to the transient X-ray behavior characterized by the short (a few hours) outburst duration, rapid (≲1 s) variability with spectral change, and large luminosity swing from 10 32 erg s −1 to 10 37 erg s −1 , the object was considered to likely be a supergiant X-ray binary with a neutron star (NS) categorized as a supergiant fast X-ray transient. Follow-up NICER and NuSTAR observations confirmed that the position of the new X-ray object is consistent with a Be star, LY CMa, which has also been identified as a B supergiant. We analyzed the NICER data obtained from 3 hr to 6 days after the discovery. The light curve reveals that the X-ray activity continued for ∼7 hr in sparse short flares, each lasting ≲100 s, and the luminosity instantaneously reached up to ∼1 × 10 38 erg s −1 . The light-curve and spectral features reasonably agree with those expected from accretion of a clumpy stellar wind onto a magnetized NS. The variability power spectrum during the brightest flare shows a broad peak at 1.1 Hz resembling a quasiperiodic oscillation (QPO). If the QPO is attributed to the Keplerian orbital frequency at the inner edge of a transient accretion disk truncated by the NS magnetosphere, the NS surface magnetic field is estimated to be ∼10 12 G.}, archive = {J_ApJ}, author = {Mutsumi Sugizaki and Tatehiro Mihara and Kohei Kobayashi and Megumi Shidatsu and Wataru Iwakiri and Keith Gendreau and Zaven Arzoumanian and Douglas J. K. Buisson and Sean N. Pike}, doi = {10.3847/1538-4357/adef4b}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {87}, shortjournal = {The Astrophys. J.}, title = {Quasiperiodic variation during a fast X-ray outburst of a high-mass X-ray binary MAXI j0709-159/LY CMa observed by NICER}, volume = {990}, year = {2025}, }
• (2025). BASS. LIII. the eddington ratio as the primary regulator of the fraction of X-ray emission in active galactic nuclei. ApJ, 990(1), 86. (www)

  @article{ , abstract = {Active galactic nuclei (AGN) emit radiation via accretion across the entire energy spectrum. While the standard disk and corona model can somewhat describe this emission, it fails to predict specific features such as the soft X-ray excess, the short-term optical/UV variability, and the observed UV/X-ray correlation in AGN. In this context, the fraction of AGN emission in different bands (i.e., bolometric corrections) can be useful to better understand the accretion physics of AGN. Past studies have shown that the X-ray bolometric corrections are strongly dependent on the physical properties of AGN, such as their luminosities and Eddington ratios. However, since these two parameters depend on each other, it has been unclear which is the main driver of the X-ray bolometric corrections. We present here results from a large study of hard-X-ray-selected (14–195 keV) nearby ( z < 0.1) AGN. Based on our systematic analysis of the simultaneous optical-to-X-ray spectral energy distributions of 236 unobscured AGN, we found that the primary parameter controlling the X-ray bolometric corrections is the Eddington ratio. Our results show that, while the X-ray bolometric correction increases with the bolometric luminosity for sources with intermediate Eddington ratios (0.01–1), this dependence vanishes for sources with lower Eddington ratios (<0.01). This could be used as evidence for a change in the accretion physics of AGN at low Eddington ratios.}, archive = {J_ApJ}, author = {Kriti Kamal Gupta and Claudio Ricci and Alessia Tortosa and Matthew J. Temple and Michael J. Koss and Benny Trakhtenbrot and Franz E. Bauer and Ezequiel Treister and Richard Mushotzky and Elias Kammoun and Iossif Papadakis and Kyuseok Oh and Alejandra Rojas and Chin-Shin Chang and Yaherlyn Diaz and Arghajit Jana and Darshan Kakkad and Ignacio del Moral-Castro and Alessandro Peca and Meredith C. Powell and Daniel Stern and C. Megan Urry and Fiona Harrison}, doi = {10.3847/1538-4357/adf0f8}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {86}, shortjournal = {The Astrophys. J.}, title = {BASS. LIII. the eddington ratio as the primary regulator of the fraction of X-ray emission in active galactic nuclei}, volume = {990}, year = {2025}, }
• (2025). Choosing suitable noise models for nanohertz gravitational-wave astrophysics. ApJ, 990(1), 85. (www)

  @article{ , abstract = {Accurately estimating the parameters of the nanohertz gravitational-wave background is essential for understanding its origin. The background is typically modeled with a power-law spectrum, parameterized with an amplitude A , which describes its intensity, and a spectral index γ , which describes how the background varies with frequency. Different collaborations have produced varied estimates of γ , some in tension with the value of γ = 13/3 expected for circular, gravitational-wave-driven binary black holes. However, estimates of A and γ can be affected by systematic errors and misspecified noise models. We investigate how systematic errors—which may plausibly be present in pulsar timing analyses—can shift inferences about A , γ . We demonstrate that conservatively incorporating noise sources into the model that are not actually present in the data does not produce bias inferences in practice. This addresses concerns that an overly complex noise model might lead to bias from a needlessly conservative prior. Our results highlight the importance of using comprehensive noise models in pulsar timing analyses to ensure accurate and reliable parameter estimation of the gravitational-wave background.}, archive = {J_ApJ}, author = {Valentina Di Marco and Andrew Zic and Ryan M. Shannon and Eric Thrane and Atharva D. Kulkarni}, doi = {10.3847/1538-4357/adf108}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {85}, shortjournal = {The Astrophys. J.}, title = {Choosing suitable noise models for nanohertz gravitational-wave astrophysics}, volume = {990}, year = {2025}, }
• (2025). The hα concentration of local star-forming galaxies: Implications for galaxy structure formation. ApJ, 990(1), 84. (www)

  @article{ , abstract = {In this work, we present a study on the H α emission line flux concentration of 3098 low-redshift star-forming galaxies (SFGs) using the MaNGA data available in the Data Release 17 from the Sloan Digital Sky Survey (SDSS). We define the H α flux concentration index ( C H α ) as {C}_{{\mathrm{H\alpha }}}={F}_{{{\rm{H}}}\alpha ,0.8\,{R}_{{{\rm{e}}}}}/{F}_{{{\rm{H}}}\alpha ,1.5\,{R}_{{{\rm{e}}}}} , where {F}_{{{\rm{H}}}\alpha ,0.8\,{R}_{{{\rm{e}}}}} and {F}_{{{\rm{H}}}\alpha ,1.5\,{R}_{{{\rm{e}}}}} are the cumulative H α flux inside 0.8 and 1.5 r -band effective radii, respectively. We find that C H α is strongly correlated with the luminosity-weighted stellar age gradient. C H α is also sensitive to environmental effects, in the sense that low-mass satellite galaxies below the star formation main sequence (SFMS) tend to have higher C H α . For central galaxies, we find that massive disk galaxies with enhanced star formation rates tend to have higher C H α , while such a phenomenon is not seen in the low-mass regime. We interpret this as evidence that compaction events more frequently occur in the high-mass regime, which eventually results in the buildup of prominent bulges in massive SFGs. Implications of these findings for galaxy structure formation are discussed.}, archive = {J_ApJ}, author = {Zhizheng Pan and Xianzhong Zheng and Xu Kong}, doi = {10.3847/1538-4357/adf2aa}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {84}, shortjournal = {The Astrophys. J.}, title = {The hα concentration of local star-forming galaxies: Implications for galaxy structure formation}, volume = {990}, year = {2025}, }
• (2025). CANUCS/Technicolor: JWST medium-band photometry finds half of the star formation at z > 7.5 is obscured. ApJ, 990(1), 83. (www)

  @article{ , abstract = {We present a sample of 110 high-redshift ( z > 7.5) galaxies from the CANUCS and Technicolor surveys, showcasing photometry in every wide- and medium-band NIRCam filter in addition to ancillary Hubble Space Telescope data sampling 0.4–5 μ m (22 JWST bands out of 29 bands total). Additionally, 47 (43%) galaxies in our sample meet criteria to be classified as extreme emission line galaxies, 17 (15%) of which are completely missed by typical dropout selections due to faint ultraviolet (UV) emission. By fitting the spectral energy distributions covering the rest-frame UV to optical at z > 7.5, we investigate the dust obscuration properties, giving an unbiased view of dust buildup in high-redshift galaxies free from spectroscopic follow-up selection effects. Dust attenuation correlates with stellar mass, but more strongly with star formation rate. We find typical galaxies at z > 7.5 have ∼25% of their star formation obscured. However, since galaxies with higher star formation rates suffer more attenuation, ∼50% of the total star formation rate density at 7.5 < z < 9 is obscured. The obscured fraction drops to ∼25% in our 9 < z < 12 bin, possibly due to substantial dust grain growth in the interstellar medium not having time to occur. Extrapolating the decline in dust obscuration of galaxies to higher redshifts, we infer that dust obscuration should approach zero at z > 15, implying that epoch as when dust first forms in bright galaxies.}, archive = {J_ApJ}, author = {Nicholas S. Martis and Sunna Withers and Maruša Bradač and Adam Muzzin and Giordano Felicioni and Roberto Abraham and Yoshihisa Asada and Gabe Brammer and Guillaume Desprez and Anishya Harshan and Kartheik G. Iyer and Naadiyah Jagga and Jon Judež and Danilo Marchesini and Vladan Markov and Rosa M. Mérida and Gaël Noirot and Gregor Rihtaršič and Ghassan T. E. Sarrouh and Marcin Sawicki and Victoria Strait and Roberta Tripodi and Chris Willott}, doi = {10.3847/1538-4357/adf32a}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {83}, shortjournal = {The Astrophys. J.}, title = {CANUCS/Technicolor: JWST medium-band photometry finds half of the star formation at z > 7.5 is obscured}, volume = {990}, year = {2025}, }
• (2025). Unraveling the variation mechanism of CTA 102: A combined spectral and polarization investigation. ApJ, 990(1), 82. (www)

  @article{ , abstract = {The variation mechanism of blazars has been a longstanding question. As a target exhibiting extreme variability, CTA 102 offers a unique window into this puzzle. In this study, we collect multiwavelength flux data, optical spectra, and polarization data of CTA 102 spanning approximately 10 yr. We apply the localized cross-correlation function to analyze the correlation between the multiwavelength light curves. Based on the lag analysis, we find that the γ -ray, optical, and X-ray emitting regions are cospatial, all located at 4.{6}_{-1.1}^{+1.1} pc upstream of the radio emitting region. On long timescales, the optical spectral behavior exhibits a transition from the redder-when-brighter trend to the bluer-when-brighter trend. Similarly, the γ -ray spectral behavior turns from the softer-when-brighter trend to the harder-when-brighter trend. The trend transitions could be explained by the two-component model, via the modulation of either the Doppler factor δ or the intrinsic peak frequency {\nu }_{p}^{{\prime} } . For the long-term behavior of the polarization degree (PD), we find that the two-component model can also quantitatively explain the correlation between the PD and the optical flux. On short timescales, the clockwise rotation on the q – u plane could be explained by the helical jet model, while the oscillation on the q – u plane may result from variations of the compression coefficient within the shock-in-jet model.}, archive = {J_ApJ}, author = {Chen-Li Ma and Jun-Hao Deng and Yun-Guo Jiang}, doi = {10.3847/1538-4357/adef14}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {82}, shortjournal = {The Astrophys. J.}, title = {Unraveling the variation mechanism of CTA 102: A combined spectral and polarization investigation}, volume = {990}, year = {2025}, }
• (2025). The physical origin and time lag of multifrequency flares from sgr a*. ApJ, 990(1), 81. (www)

  @article{ , abstract = {Sagittarius A*, the supermassive black hole at the center of our galaxy, exhibits flares across various wavelengths, yet its origin remains elusive. We performed 3D two-temperature general relativistic magnetohydrodynamic simulations of magnetized accretion flows initialized from multiloop magnetic field configuration onto a rotating black hole and conducted general relativistic radiative transfer (GRRT) calculations considering contributions from both thermal and nonthermal synchrotron emission processes. Our results indicate that the polarity inversion events from the multiloop magnetic field configurations can generate 138 THz flares consistent with observations with the help of nonthermal emission. By tracing the intensity evolution of light rays in GRRT calculations, we identify the precise location of the flaring region and confirm that it originates from a large-scale polarity inversion event. We observe time delays between different frequencies, with lower-frequency radio flares lagging behind higher frequencies due to plasma self-absorption in the disk. The time delay between near-infrared and 43 GHz flares can reach up to ∼50 minutes, during which the flaring region gradually shifts outward, becoming visible at lower frequencies. Our study confirms that large-scale polarity inversion in a standard and normal evolution accretion flow with a multiloop initial magnetic configuration can be a potential mechanism driving flares from Sgr A*.}, archive = {J_ApJ}, author = {Hong-Xuan Jiang and Yosuke Mizuno and Indu K. Dihingia and Feng Yuan and Xi Lin and Christian M. Fromm and Antonios Nathanail and Ziri Younsi}, doi = {10.3847/1538-4357/adf1e5}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {81}, shortjournal = {The Astrophys. J.}, title = {The physical origin and time lag of multifrequency flares from sgr a*}, volume = {990}, year = {2025}, }
• (2025). Key physical parameters influencing fragmentation and multiplicity in dense cores of orion a. ApJ, 990(1), 80. (www)

  @article{ , abstract = {When dense cores in molecular clouds or filamentary structures collapse and form protostars, they may undergo fragmentation and form binary or multiple systems. In this paper, we investigate the key mechanisms influencing fragmentation, by comparing the physical conditions of fragmented and unfragmented dense cores (∼0.1 pc) in Orion A. Utilizing archival submillimeter continuum data from the James Clerk Maxwell Telescope (JCMT) and the Atacama Large Millimeter/submillimeter Array survey of Class 0 and I protostars at 0 \mathop{.}\limits^{^{\prime\prime} } 1 resolution, we identified 38 dense cores hosting single protostars and 15 cores hosting binary or multiple systems. We measured the dense core properties using Herschel dust temperature, Nobeyama 45 m N 2 H + J = 1−0, and JCMT polarization data. Our results reveal that the dense cores hosting binary/multiple systems exhibit significantly higher densities and Mach numbers compared to those hosting single protostars, while there are no correlations between the occurrence of fragmentation and the energy ratios of turbulence and magnetic field to gravity. Our results suggest that the higher density and supersonic turbulence of dense cores can lead to local collapse and fragmentation, to form binary/multiple systems, while the magnetic field has limited influence on fragmentation in the dense cores in Orion A.}, archive = {J_ApJ}, author = {Jo-Shui Kao and Hsi-Wei Yen and Shih-Ping Lai}, doi = {10.3847/1538-4357/adf206}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {80}, shortjournal = {The Astrophys. J.}, title = {Key physical parameters influencing fragmentation and multiplicity in dense cores of orion a}, volume = {990}, year = {2025}, }
• (2025). Intra-night optical variability and radio characteristics of extremely radio-loud narrow-line seyfert 1 galaxies. ApJ, 990(1), 79. (www)

  @article{ , abstract = {Narrow-line Seyfert 1 galaxies (NLS1s) are generally known to be radio-quiet active galactic nuclei, but a tiny subset of them are found to be extremely radio-loud with radio loudness parameter ( R 1.4 GHz ) > 100. Given their rarity, we investigated intra-night optical variability (INOV) and radio characteristics of a sample of 16 extremely radio-loud NLS1s. For all but four sample sources we report intra-night photometric monitoring for the first time with at least one monitoring session per source lasting for a minimum of 3.0 hr duration. In our sample, we detect INOV with a high duty cycle (up to 25%) and large average amplitude ( \overline{\psi } ∼ 0.16) similar to that found in blazars. Using 3.0 GHz Very Large Array Sky Survey and auxiliary multifrequency radio data we find that our RL-NLS1s are luminous ( L 3.0 GHz ≥ 10 24 W Hz −1 ), compact (less than a few kpc), variable, flat spectrum ( α radio > −0.5) radio sources. The INOV, radio characteristics, and radio luminosity ( L 1.4 GHz ) versus supermassive black hole mass ( M SMBH ) plot infer that extremely radio-loud NLS1s are low- z and low-luminosity analogs of flat spectrum radio quasars wherein the former are powered by, on average, one order-of-magnitude less massive SMBHs.}, archive = {J_ApJ}, author = {Veeresh Singh and Parveen Kumar and Avik Kumar Das and Vineet Ojha}, doi = {10.3847/1538-4357/adf210}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {79}, shortjournal = {The Astrophys. J.}, title = {Intra-night optical variability and radio characteristics of extremely radio-loud narrow-line seyfert 1 galaxies}, volume = {990}, year = {2025}, }
• (2025). Cosmogenic neutrino point source and KM3-230213A. ApJ, 990(1), 78. (www)

  @article{ , abstract = {Cosmogenic neutrinos (CNs) are produced by ultra-high-energy cosmic rays (UHECRs) interacting with cosmic background radiation. We investigated the properties of CN point/extended sources, i.e., the neutrino spectrum and angular profile as functions of time, by assuming that UHECR sources are transient events, such as gamma-ray bursts. The properties depend much on the intergalactic magnetic field (IGMF), but the angular extent is in general subdegree, within which the CN flux can overshoot the diffuse CN flux in early time. The nearby CN point sources could be detected for the low IGMF case by future neutrino telescopes. The recent KM3-230213A event is possible to account for by a nearby transient CN source, rather than diffuse CN emission. Observations of CN point sources will provide a chance to search for UHECR sources.}, archive = {J_ApJ}, author = {Qinyuan Zhang and Tian-Qi Huang and Zhuo Li}, doi = {10.3847/1538-4357/adf21c}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {78}, shortjournal = {The Astrophys. J.}, title = {Cosmogenic neutrino point source and KM3-230213A}, volume = {990}, year = {2025}, }
• (2025). High-resolution observation of minifilament eruptions near a coronal hole boundary and their response in the solar corona. ApJ, 990(1), 77. (www)

  @article{ , abstract = {We investigated minifilament (MF) eruptions (MFEs) near coronal hole (CH) boundaries to explore their role in coronal dynamics and their potential contributions to the solar wind. Using high-resolution H α images from the 1.6 m Goode Solar Telescope at Big Bear Solar Observatory and Atmospheric Imaging Assembly 193 Å extreme ultraviolet (EUV) data from Solar Dynamics Observatory, we analyzed 28 MFE events over 7.5 hr of observation spanning 5 days. The three largest MF eruptions triggered distinct coronal responses: two consecutive MFEs produced a small-scale eruptive coronal ejection, while the other generated a jetlike brightening. Furthermore, the 25 smaller-scale MFEs were associated with localized brightenings in coronal bright points. These findings suggest that MFs play a significant role in transferring mass and magnetic flux to the corona, particularly within CH regions. We found a certain trend that the size of MFEs is correlated with the EUV emissions. In addition, we observed magnetic flux cancellation associated with MFEs. However, except for a few of the largest MFEs, quantitative analysis of magnetic field evolution is beyond the capability of the data. These results underscore the importance of MFEs in the dynamic coupling between the chromosphere and corona, highlighting their potential role in shaping heliospheric structures.}, archive = {J_ApJ}, author = {Nengyi Huang and Haimin Wang}, doi = {10.3847/1538-4357/adf226}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {77}, shortjournal = {The Astrophys. J.}, title = {High-resolution observation of minifilament eruptions near a coronal hole boundary and their response in the solar corona}, volume = {990}, year = {2025}, }
• (2025). Characterizing 3D magnetic fields and turbulence in h i clouds. ApJ, 990(1), 76. (www)

  @article{ , abstract = {3D Galactic magnetic fields are critical for understanding the interstellar medium, Galactic foreground polarization, and the propagation of ultra-high-energy cosmic rays. Leveraging recent theoretical insights into anisotropic magnetohydrodynamic (MHD) turbulence, we introduce a deep learning framework to predict the full 3D magnetic field structure, including the plane-of-sky (POS) position angle, line-of-sight (LOS) inclination, magnetic field strength, sonic Mach number ( M s ), and Alfvén Mach number ( M A ), from spectroscopic H I observations. The deep learning model is trained on synthetic H I emission data generated from multiphase 3D MHD simulations. We then apply the trained model to observational data from the Commensal Radio Astronomy FAST Survey, presenting maps of 3D magnetic field orientation, magnetic field strength, M s , and M A for two H I clouds—a low-velocity cloud and an intermediate-velocity cloud, which overlap in the POS yet reside at different LOS distances. The deep-learning-predicted POS magnetic field position angles align closely with those determined using the velocity gradient technique, whose integrated results are consistent with independent measurements from Planck 353 GHz polarization data. This study demonstrates the potential of deep learning approaches as powerful tools for modeling the 3D distributions of 3D Galactic magnetic fields and turbulence properties throughout the Galaxy.}, archive = {J_ApJ}, author = {Yue Hu}, doi = {10.3847/1538-4357/adf32e}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {76}, shortjournal = {The Astrophys. J.}, title = {Characterizing 3D magnetic fields and turbulence in h i clouds}, volume = {990}, year = {2025}, }
• (2025). Cosmic-ray feedback from supernovae in a parker-unstable medium. ApJ, 990(1), 75. (www)

  @article{ , abstract = {Supernova energy drives interstellar medium (ISM) turbulence and can help launch galactic winds. What difference does it make if 10% of the energy is initially deposited into cosmic rays? To help answer this question and study cosmic-ray feedback, we perform galactic patch simulations of a stratified ISM in a low star formation rate, high magnetic field regime. We compare two magnetohydrodynamic and cosmic-ray simulations, which are identical except for how each supernova’s energy is injected. In one, 10% of the energy is injected as cosmic-ray energy. In the other case, energy injection is strictly thermal and kinetic. We find that cosmic-ray injections drive a faster, hotter, and more massive outflow long after the injections occur. Both simulations show the formation of cold clouds (with a total mass fraction > 50%) through the Parker instability and thermal instability. The Parker instability simultaneously produces high mass loading factors η > 10 3 as it does not directly require star formation and supernovae. We also show how the Parker instability naturally leads to a decorrelation of cosmic-ray pressure and gas density. This decorrelation leads to a significant decrease in the calorimetric fraction for injected cosmic rays, but it depends on having a highly resolved magnetic field.}, archive = {J_ApJ}, author = {Roark Habegger and Ellen G. Zweibel}, doi = {10.3847/1538-4357/adf4d7}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {75}, shortjournal = {The Astrophys. J.}, title = {Cosmic-ray feedback from supernovae in a parker-unstable medium}, volume = {990}, year = {2025}, }
• (2025). Dynamical instability of multiplanet systems and free-floating planets. ApJ, 990(1), 74. (www)

  @article{ , abstract = {The ejection of planets by the instability of planetary systems is a potential source of free-floating planets. We numerically simulate multiplanet systems to study the evolution process, the properties of the surviving systems, and the statistics of the ejected planets. For systems with only super-Earth planets, we find that the time (in units of the orbital period P 1 of the innermost planet) for the system to lose the first planet by collision or ejection increases with the semimajor axis of the innermost planet. In contrast, the time (in units of P 1 ) for the first close encounter between two planets is identical. These two timescales also depend differently on the orbital spacing between the planets. Most systems with only super-Earths do not have planets ejected. In systems with super-Earths and a cold Jupiter, we discover that a cold Jupiter significantly increases the probability of ejection of the super-Earths by close encounters. For 38% of the ejected super-Earths, most velocities relative to their parent stars are smaller than 6 km s −1 . We conservatively estimate that more than 86% of the surviving two-planet systems in the super-Earths-plus-cold-Jupiter sample are long-term stable by using empirical criteria. Most super-Earths in the remaining two-planet systems are on highly elliptical but stable orbits and have migrated inward compared with their initial states.}, archive = {J_ApJ}, author = {Ruocheng Zhai and Man Hoi Lee and Tianjun Gan and Shude Mao}, doi = {10.3847/1538-4357/adf557}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {74}, shortjournal = {The Astrophys. J.}, title = {Dynamical instability of multiplanet systems and free-floating planets}, volume = {990}, year = {2025}, }
• (2025). Parker solar probe observations of turbulence and waves between a current sheet and an interplanetary coronal mass Ejection–Driven shock. ApJ, 990(1), 73. (www)

  @article{ , abstract = {We report on unusual magnetic wave activity seen in a region between the crossing of a current sheet and an interplanetary shock by the Parker Solar Probe (PSP). The PSP observed a shock driven by an interplanetary coronal mass ejection on 2021 June 30 at 14:58:19 at 0.76 au. Prior to the arrival of the shock, PSP encountered a current sheet on 2021 June 30 at 14:54:54. Through an analysis of the magnetic field and plasma measurements, we determine that the shock is a fast forward quasi-parallel shock. The magnetic field in the region between the current sheet and the shock was characterized by enhanced magnetic wave activity. To investigate the plasma waves in the region, a wavelet technique is applied to obtain the magnetic field fluctuation power spectral density, normalized reduced helicity, and magnetic field fluctuation hodogram. The results of the analysis reveal that the waves present in this region demonstrate right-hand polarization and have a relatively broad range of frequencies in the spacecraft frame. Our analyses reveal the simultaneous presence of low-frequency magnetohydrodynamic waves and whistler waves within this region and note that these waves become active precisely at the time of the current sheet crossing. The coexistence of different types of waves within this region presents a unique opportunity for further investigation and deepening our understanding of the underlying physical mechanisms governing these phenomena.}, archive = {J_ApJ}, author = {Juan Zhang and Joe Giacalone and Xiaohang Chen and Lan K. Jian and Kristopher G. Klein}, doi = {10.3847/1538-4357/adf55b}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {73}, shortjournal = {The Astrophys. J.}, title = {Parker solar probe observations of turbulence and waves between a current sheet and an interplanetary coronal mass Ejection–Driven shock}, volume = {990}, year = {2025}, }
• (2025). FEAST: Probing the stellar population of the starburst dwarf galaxy NGC 4449 with JWST/NIRCam. ApJ, 990(1), 72. (www)

  @article{ , abstract = {We present new JWST/NIRCam observations of the starburst irregular galaxy NGC 4449, obtained in Cycle 1 as part of the Feedback in Emerging extrAgalactic Star clusTers program, which we use to investigate its resolved stellar populations and their spatial distributions. NGC 4449 near-IR color–magnitude diagrams reveal a broad range of stellar populations, spanning different evolutionary phases, from young main sequence stars, to old red giant branch stars and asymptotic giant branch (AGB) stars. The analysis of their spatial distributions shows that younger (≤10 Myr) populations form an S-shaped distribution aligned with the galaxy’s north–south axis, while stars aged 10–60 Myr show shifting concentrations from the north to the south, consistent with the possibility that external interactions or tidal effects may have triggered star formation in spatially distinct bursts. Clusters of comparable ages generally follow these distributions, suggesting that cluster and field stars form at the same pace in each galaxy region. Thanks to the unprecedented high-spatial resolution and sensitivity of the JWST data, we recover a clear gap between oxygen-rich and the carbon star branch of the AGB population, as well as the presence of a massive AGB star “finger.” The analysis of these stars can provide constraints on AGB evolution models and dust production in this galaxy. These results confirm NGC 4449's status as a compelling example of a local dwarf starburst galaxy undergoing complex and possibly externally driven star formation and underscore the power of JWST in probing the full lifecycle of stars in nearby starburst systems.}, archive = {J_ApJ}, author = {Matteo Correnti and Giacomo Bortolini and Flavia Dell’Agli and Angela Adamo and Michele Cignoni and Elena Sacchi and Monica Tosi and Alex Pedrini and Anne S. M. Buckner and Daniela Calzetti and Ana Duarte-Cabral and Bruce G. Elmegreen and Helena Faustino Vieira and John S. Gallagher and Kathryn Grasha and Benjamin Gregg and Kelsey E. Johnson and Thomas S.-Y. Lai and Drew Lapeer and Sean T. Linden and Matteo Messa and Goran Ostlin and Elena Sabbi and Linda J. Smith and Paolo Ventura}, doi = {10.3847/1538-4357/adec74}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {72}, shortjournal = {The Astrophys. J.}, title = {FEAST: Probing the stellar population of the starburst dwarf galaxy NGC 4449 with JWST/NIRCam}, volume = {990}, year = {2025}, }
• (2025). The structure of the giant radio fossil in the ophiuchus galaxy cluster. ApJ, 990(1), 71. (www)

  @article{ , abstract = {We present high-sensitivity follow-up observations of the giant fossil radio lobe in the Ophiuchus galaxy cluster with the upgraded Giant Metrewave Radio Telescope in the 125–250 and 300–500 MHz frequency bands. The new data have sufficient angular resolution to exclude compact sources and enable us to trace the faint extended emission from the relic lobe to a remarkable distance of 820 kpc from the cluster center. The new images reveal intricate spatial structure within the fossil lobe, including narrow (5–10 kpc), long (70–100 kpc) radio filaments embedded within the diffuse emission at the bottom of the lobe. The filaments exhibit a very steep spectrum ( S ν ∝ ν − α with α ∼ 3), significantly steeper than the ambient synchrotron emission from the lobe ( α ∼ 1.5–2); they mostly disappear in recently published MeerKAT images at 1.28 GHz. Their origin is unclear; similar features observed in some other radio lobes typically have a spectrum flatter than that of their ambient medium. These radio filaments may trace regions where the magnetic field has been stretched and amplified by gas circulation within the rising bubble. The spectrum of the brightest region of the radio lobe exhibits a spectral break, which corresponds to a radiative cooling age of the fossil lobe of approximately 174 Myr, giving a date for this most powerful active galactic nucleus explosion.}, archive = {J_ApJ}, author = {S. Giacintucci and M. Markevitch and T. Clarke and Daniel R. Wik}, doi = {10.3847/1538-4357/adef4a}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {71}, shortjournal = {The Astrophys. J.}, title = {The structure of the giant radio fossil in the ophiuchus galaxy cluster}, volume = {990}, year = {2025}, }
• (2025). Cluster lensing mass inversion (CLUMI+): Combining dynamics and weak lensing around galaxy clusters. ApJ, 990(1), 70. (www)

  @article{ , abstract = {We present clumi+ , a self-consistent, multiprobe methodology for reconstructing the mass distribution in and around galaxy clusters by combining gravitational lensing and dynamical observations. Building on the joint likelihood framework of K. Umetsu, clumi+ integrates weak-lensing shear and magnification data with projected escape velocity measurements in the cluster infall region, yielding tighter constraints on the gravitational potential without relying on equilibrium assumptions. The mass distribution is modeled using a flexible, piecewise-defined convergence profile that characterizes the azimuthally averaged surface mass density within the lensing field, transitioning to a projected power-law form at larger radii where phase-space constraints complement lensing. Additional strong-lensing constraints are incorporated via central aperture-mass measurements, enabling full-scale mass reconstruction from the cluster core to the outskirts. We validate clumi+ using synthetic weak-lensing and phase-space data for a massive cluster from the IllustrisTNG simulations, demonstrating unbiased recovery of projected and three-dimensional mass profiles and achieving 10%–30% improvement in precision at large radii. As a case study, we apply clumi+ to A2261, combining Subaru and Hubble Space Telescope weak+strong-lensing data with spectroscopic measurements from the Hectospec Cluster Survey. This analysis demonstrates the power of multiprobe, equilibrium-free modeling for robust cluster mass reconstruction.}, archive = {J_ApJ}, author = {Keiichi Umetsu and Michele Pizzardo and Antonaldo Diaferio and Margaret J. Geller}, doi = {10.3847/1538-4357/aded91}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {70}, shortjournal = {The Astrophys. J.}, title = {Cluster lensing mass inversion (CLUMI+): Combining dynamics and weak lensing around galaxy clusters}, volume = {990}, year = {2025}, }
• (2025). Probing evolution of long gamma-ray burst properties through their cosmic formation history. ApJ, 990(1), 69. (www)

  @article{ , abstract = {The astrophysics of long gamma-ray burst (LGRB) progenitors as well as possible cosmological evolution in their properties still poses many open questions. Previous studies suggest that the LGRB rate density (LGRB-RD) follows the cosmic star formation rate density (SFRD) only at high- z and attribute this to the metallicity evolution of progenitor stars. For low z , opinions differ on whether the uptick in the LGRB-RD is due to a distinct class of low-luminosity GRBs or perhaps even a different progenitor subclass. To investigate these questions, we utilize data from the Neil Gehrels Swift Observatory and ground-based observatories (redshift). To test the hypothesis that the observations can be mapped (with/without evolution) to the well-established cosmic SFRD, we consider three cases: no evolution, beaming angle evolution, and a simple power-law evolution. The comparison shows that the “no evolution” case can be ruled out. Our study highlights that the beaming angle evolution or the simple power-law evolution is also not sufficient to obtain a good match between the LGRB-RD and SFRD. Rather, the inclusion of multiple evolving properties of LGRBs in combination appears to be required to match the two rate densities in their entirety.}, archive = {J_ApJ}, author = {Nikita S. Khatiya and Maria Giovanna Dainotti and Aditya Narendra and Dhruv S. Bal and Aleksander Ł. Lenart and Dieter H. Hartmann}, doi = {10.3847/1538-4357/adf219}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {69}, shortjournal = {The Astrophys. J.}, title = {Probing evolution of long gamma-ray burst properties through their cosmic formation history}, volume = {990}, year = {2025}, }
• (2025). The first model-independent chromatic microlensing search: No evidence in the gravitational wave catalog of LIGO–Virgo–KAGRA. ApJ, 990(1), 68. (www)

  @article{ , abstract = {The lensing of gravitational waves (GWs) due to intervening matter distribution in the Universe can lead to chromatic and achromatic signatures in the wave-optics and geometrical-optics limit, respectively. This makes it difficult to model the unknown mass distribution of the lens and hence requires a model-independent lensing detection technique from GW data. We perform the first model-independent microlensing search in the wave-optics limit on the 72 superthreshold GW events observed with both the LIGO detectors up to the third observation catalog, GWTC-3 of LIGO–Virgo–KAGRA, using the analysis method μ - GLANCE . These unmodelled searches pick up one plausible candidate, GW190408_181802, with a slightly above-threshold residual amplitude compared to the residual expected from detector noise. However, exploring the microlensing modulation signatures on this event, we do not find any conclusive evidence of the microlensing signal in the data. With this, we confidently rule out the presence of any statistically significant microlensing signal in the 72 events up to GWTC-3 in a model-independent way.}, archive = {J_ApJ}, author = {Aniruddha Chakraborty and Suvodip Mukherjee}, doi = {10.3847/1538-4357/adf330}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {68}, shortjournal = {The Astrophys. J.}, title = {The first model-independent chromatic microlensing search: No evidence in the gravitational wave catalog of LIGO–Virgo–KAGRA}, volume = {990}, year = {2025}, }
• (2025). JWST NIRCam observations of the globular cluster population of RXJ 2129.7+0005. ApJ, 990(1), 67. (www)

  @article{ , abstract = {We present an analysis of the globular cluster (GC) population in the galaxy cluster RXJ 2129.7+0005 ( z = 0.234) based on JWST NIRCam imaging in three filters: F115W, F150W, and F200W. We use this material to provide a detailed look at the color–magnitude distribution of the GCs and their spatial distribution around the central giant galaxy. We identified 3160 GC candidates brighter than F150W = 29.5, and assessed photometric completeness through artificial star tests. We determined that the GCs follow a radial power-law distribution with an index of 1.58 ± 0.04, with the redder GCs exhibiting a slightly greater central concentration. Their spatial distribution is also highly elliptical, closely following the shape of the brightest cluster galaxy halo light.}, archive = {J_ApJ}, author = {Kaitlyn E. Keatley and William E. Harris}, doi = {10.3847/1538-4357/adf5c4}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {67}, shortjournal = {The Astrophys. J.}, title = {JWST NIRCam observations of the globular cluster population of RXJ 2129.7+0005}, volume = {990}, year = {2025}, }
• (2025). Reexamination of the CO absorption line in the m87 nucleus. ApJ, 990(1), 66. (www)

  @article{ , abstract = {We analyzed the archival Atacama Large Millimeter/submillimeter Array data of the nuclear region of M87 and evaluated the molecular gas content from the CO(2–1) absorption line. We found an enigmatic variability in the absorption line depth between two epochs separated by only two months. We reexamined the data set used in the analysis and found that the bandpass calibration source within the same data set also revealed a similar absorption line structure. Furthermore, we observed a rise in the system noise temperature spectrum. We concluded that the absorption line structure identified in a previous study, and attributed to CO(2–1), does not originate from M87 but instead results from telluric contamination, and that we still have only the upper limit on the molecular gas around the nucleus of M87.}, archive = {J_ApJ}, author = {Norita Kawanaka and Hiroshi Nagai and Yutaka Fujita}, doi = {10.3847/1538-4357/adf726}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {66}, shortjournal = {The Astrophys. J.}, title = {Reexamination of the CO absorption line in the m87 nucleus}, volume = {990}, year = {2025}, }
• (2025). Spectral energy distribution fitting of globular clusters in NGC 4874: Masses and metallicities. ApJ, 990(1), 65. (www)

  @article{ , abstract = {In most nearby galaxies, photometry of the integrated light of their globular clusters (GCs) has been obtained in only two filters, yielding just a single color index. However, NGC 4874, the brightest central galaxy in the Coma Cluster, now has Hubble Space Telescope photometry available in 10 filters, giving us a special opportunity to test spectral energy distribution (SED) fitting procedures on GCs in distant galaxies. We fitted 29 of the brightest GCs with a library of SEDs from E-MILES and calculated the best-fit metallicity and mass of each cluster. Using the fitted masses and luminosities derived from the reddest magnitudes, in the flat portion of the GC spectrum, we also calculated inferred mass-to-light ratios for our sample GCs; these were in the range (M/L) ≃ 2–4, slightly larger than the average values for Milky Way GCs but within the conventional range.}, archive = {J_ApJ}, author = {Kate Hartman and William E. Harris and Jinoo Kim}, doi = {10.3847/1538-4357/adf7ac}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {65}, shortjournal = {The Astrophys. J.}, title = {Spectral energy distribution fitting of globular clusters in NGC 4874: Masses and metallicities}, volume = {990}, year = {2025}, }
• (2025). Intermittency in voyager’s magnetic field beyond the heliosphere. ApJ, 990(1), 64. (www)

  @article{ , abstract = {As the two Voyager spacecraft traveled beyond the heliosphere, they encountered a magnetic field environment that had never been observed before. Studies have attempted to characterize this new regime by examining the magnetic field intermittency. This is typically done by fitting the optimal kappa distribution function and interpreting its q -statistics to characterize the magnetic field increments. Using this approach, recent findings concluded that beyond a certain distance, the magnetic field increments in the very local interstellar medium (VLISM) follow Gaussian statistics, unlike those both inside the heliosphere and in the region just beyond the widely accepted heliopause location, raising questions about the heliopause identification. This study explores this issue in detail by (1) optimizing the derivation of the distribution function, (2) examining whether and how the results depend on increment windows and time periods, and (3) determining the statistical behavior of the examined time series. Using magnetic field measurements from Voyager 1, we present two independent techniques and introduce a statistical framework to systematically analyze the distributions of magnetic field increments. Contrary to previous findings, we find that magnetic field increments in the VLISM do not follow a Gaussian distribution (κ → ∞) and instead are in the non-Gaussian range of kappa values (3–7, when analyzed on a 30 days statistical period). We further demonstrate how erroneous, statistically induced results can arise that mimic Gaussian-like results when mixing different structures in such analyses. Our results show that Voyager 1 still travels in the intermittent magnetic field environment of the VLISM.}, archive = {J_ApJ}, author = {L. Y. Khoo and G. Livadiotis and D. J. McComas and M. E. Cuesta and J. S. Rankin}, doi = {10.3847/1538-4357/adef58}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {64}, shortjournal = {The Astrophys. J.}, title = {Intermittency in voyager’s magnetic field beyond the heliosphere}, volume = {990}, year = {2025}, }
• (2025). Absolute calibration of cluster mira variables to provide a new anchor for the hubble constant determination. ApJ, 990(1), 63. (www)

  @article{ , abstract = {Mira variables in globular clusters can provide an accurate and precise absolute calibration of their period–luminosity relations (PLRs) to independently anchor the cosmic distance scale and determine the Hubble constant. We present homogeneous near-infrared ( JHK s ) time-series photometric observations of a sample of 55 candidate long-period variables in 18 globular clusters covering a wide metallicity range (−1.7 < [Fe/H] < − 0.1 dex). The Gaia proper motions, long-period variability information, and optical-infrared colors are used to identify 41 oxygen-rich Miras as members of the globular clusters. Mean luminosities of Miras in the JHK s bands are independently calibrated using the recommended distances and mean parallaxes to their host clusters. Cluster Mira PLRs exhibit scatter comparable to the Large Magellanic Cloud (LMC) variables and do not show any dependence on iron abundance for a wide range of metallicities. We establish the accuracy of cluster Miras as independent anchors by determining a distance modulus to the LMC, 18.45  ±  0.04 mag, in agreement with the 1.2% precise geometric distance. Our H -band photometry is transformed to derive Hubble Space Telescope F160W PLR for cluster Miras, providing a three-anchor baseline with the LMC and NGC 4258. We employ a three-anchor solution to determine distances to two type Ia supernovae host galaxies, NGC 1559 (31.39  ±  0.05 mag) and M101 (29.07  ±  0.04 mag), and provide a 3.7% measurement of the Hubble constant, H 0 = 73.06  ±  2.67 km s −1 Mpc −1 . Similar to Cepheids, our independent baseline solution results in a local H 0 determination that is systematically larger than its inference from the early universe probes, further supporting the ongoing Hubble tension.}, archive = {J_ApJ}, author = {Anupam Bhardwaj and Noriyuki Matsunaga and Caroline D. Huang and Adam G. Riess and Marina Rejkuba}, doi = {10.3847/1538-4357/adf20b}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {63}, shortjournal = {The Astrophys. J.}, title = {Absolute calibration of cluster mira variables to provide a new anchor for the hubble constant determination}, volume = {990}, year = {2025}, }
• (2025). An all-sky survey of white dwarf merger remnants: Far-ultraviolet is the key. ApJ, 990(1), 62. (www)

  @article{ , abstract = {The majority of merging white dwarfs leave behind a white dwarf remnant. Hot/warm DQ white dwarfs with carbon-rich atmospheres have high masses and unusual kinematics. All evidence points to a merger origin. Here, we demonstrate that far-UV (FUV) and optical photometry provides an efficient way to identify these merger remnants. We take advantage of this photometric selection to identify 167 candidates in the Galaxy Evolution Explorer All-Sky Imaging Survey footprint, and provide follow-up spectroscopy. Out of the 140 with spectral classifications, we identify 75 warm DQ white dwarfs with T eff > 10,000 K, nearly tripling the number of such objects known. Our sample includes 13 DAQ white dwarfs with spectra dominated by hydrogen and (weaker) carbon lines. Ten of these are new discoveries, including the hottest DAQ known to date, with T eff ≈ 23,000 K and M = 1.31 M ⊙ . We provide a model atmosphere analysis of all warm DQ white dwarfs found, and present their temperature and mass distributions. The sample mean and standard deviation are T eff = 14,560 ± 1970 K and M = 1.11 ± 0.09 M ⊙ . Warm DQs are roughly twice as massive as the classical DQs found at cooler temperatures. All warm DQs are found on or near the crystallization sequence. Even though their estimated cooling ages are of order 1 Gyr, their kinematics indicate an origin in the thick disk or halo. Hence, they are likely stuck on the crystallization sequence for ∼10 Gyr due to significant cooling delays from distillation of neutron-rich impurities. Future all-sky FUV surveys like Ultraviolet Explorer have the potential to significantly expand this sample.}, archive = {J_ApJ}, author = {Mukremin Kilic and Pierre Bergeron and Warren R. Brown and Simon Blouin and Gracyn Jewett and Adam Moss and Patrick Dufour and Olivier Vincent}, doi = {10.3847/1538-4357/adf1a4}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {62}, shortjournal = {The Astrophys. J.}, title = {An all-sky survey of white dwarf merger remnants: Far-ultraviolet is the key}, volume = {990}, year = {2025}, }
• (2025). Effects of outer giant planets on in situ formation of inner super-earths. ApJ, 990(1), 61. (www)

  @article{ , abstract = {Recent studies have found an observational correlation between the presence of outer giant planets and inner super-Earths, which implies that outer giants do not suppress the formation of super-Earths. We simulate late-stage in situ planet formation in the presence of outer giant planets using N -body simulations. We investigate the effects of two sets of outer giants: the four solar system giant (SSG) planets and three dynamically active giant (DAG) planets. Compared to systems without outer giants, we find that systems with SSGs tend to form inner super-Earths that are more compact, coplanar, and circular, while the systems with DAGs form inner super-Earths that are more eccentric, inclined, and widely spaced, with lower intrinsic multiplicity. Including a contribution from systems that form with DAG planets allows us to match observable quantities of super-Earths, including their two-component eccentricity distribution. However, matching the observed population requires different formation conditions prior to the giant impact stage for systems with versus without giant planets. In our model, observed super-Earths that form in the presence of dynamically active outer giants emerge from disks with lower solid surface densities and without a depleted gas stage, suggesting that the giant planets may have reduced, but not prevented, delivery and/or accretion of solids in the inner disk. With a large enough sample of inner and outer systems, we could break down occurrence rates of inner super-Earths based on the properties of outer giants, and vice versa, and then compare these conditional probabilities with simulations.}, archive = {J_ApJ}, author = {Phoebe Sandhaus and Rebekah I. Dawson and Mariah MacDonald and Cody J. Shakespeare and Sarah Morrison}, doi = {10.3847/1538-4357/adf1a6}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {61}, shortjournal = {The Astrophys. J.}, title = {Effects of outer giant planets on in situ formation of inner super-earths}, volume = {990}, year = {2025}, }
• (2025). Diversity in hydrogen-rich envelope mass of type II supernovae. III. the mass-loss and evolutionary pathways of the red supergiant progenitors. ApJ, 990(1), 60. (www)

  @article{ , abstract = {We present a comprehensive analysis of 32 type II supernovae (SNe II) with plateau phase photometry and late phase ( nebular ) spectroscopy available, aiming to bridge the gap between the surface and core of their red supergiant (RSG) progenitors. Using MESA + STELLA , we compute an extensive grid of SN II light-curve models originating from RSG with effective temperatures T eff around 3650 K and hydrogen-rich envelopes artificially stripped to varying degrees. These models are then used to derive the hydrogen-rich envelope masses M Henv for SNe II from their plateau phase light curves. Nebular spectroscopy further constrains the progenitor RSG’s luminosity log L prog and is employed to remove the degeneracies in light-curve modeling. The comparison between log L prog – M Henv reveals that M Henv spans a broad range at the same log L prog , and almost all SNe II have lower M Henv than the prediction of the default stellar wind models. We explore alternative wind prescriptions, binary evolution models, and the possibility of more compact RSG progenitors. Although binary interaction offers a compelling explanation for the nonmonotonicity and large scatter in the log L prog – M Henv relation, the high occurrence rate of partially stripped RSGs cannot be accounted for by stable binary mass transfer alone without fine-tuned orbital parameters. This highlights that, despite being the most commonly observed class of core-collapse SNe, SNe II likely originate from a variety of mass-loss histories and evolutionary pathways that are more diverse and complex than typically assumed in standard stellar evolution models.}, archive = {J_ApJ}, author = {Qiliang Fang and Takashi J. Moriya and Keiichi Maeda and Andris Dorozsmai and Javier Silva-Farfán}, doi = {10.3847/1538-4357/adf218}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {60}, shortjournal = {The Astrophys. J.}, title = {Diversity in hydrogen-rich envelope mass of type II supernovae. III. the mass-loss and evolutionary pathways of the red supergiant progenitors}, volume = {990}, year = {2025}, }
• (2025). The impact of silicate grain coagulation on millimeter emission from massive protostellar disks. ApJ, 990(1), 59. (www)

  @article{ , abstract = {Hot accretion disks around massive protostars provide a unique opportunity to study ice-free silicate grains that cannot be investigated in protoplanetary disks. We conduct a self-consistent investigation into grain-size evolution and its impact on (sub)millimeter-wave emission from massive protostellar disks. Our radiative transfer modeling accounts for dust self-scattering and includes vertical temperature gradients in the disk structure. The results show that once silicate grains grow to sizes exceeding the observing wavelength, enhanced scattering dims the disk emission by 20%–30% relative to the blackbody emission expected at the disk surface temperature. By comparing our model with Atacama Large Millimeter/submillimeter Array 1.14 mm observations of the disk around the massive protostar GGD27-MM1, we constrain the threshold velocity for collisional fragmentation of silicate grains to approximately 15 m s −1 . This fragmentation velocity is lower than the typical maximum collisional velocities in protoplanetary disks around low-mass stars, suggesting that collisional coagulation alone is insufficient for silicate dust to form rocky planetesimals in such environments. Furthermore, our analysis identifies two potential scenarios to better reproduce the bright inner-disk emission of GGD27-MM1. One possibility is that the grain growth is limited to 160 μ m by another growth barrier (e.g., collisional bouncing), reducing scattering dimming. Alternatively, the stellar luminosity may be as much as five times higher than current estimates, compensating for the reduced brightness. Future multiwavelength observations, particularly at shorter submillimeter wavelengths, will be crucial to distinguish between these scenarios and further constrain silicate grain coagulation processes in massive protostellar disks.}, archive = {J_ApJ}, author = {Ryota Yamamuro and Kei E. I. Tanaka and Satoshi Okuzumi}, doi = {10.3847/1538-4357/adf49c}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {59}, shortjournal = {The Astrophys. J.}, title = {The impact of silicate grain coagulation on millimeter emission from massive protostellar disks}, volume = {990}, year = {2025}, }
• (2025). Intergalactic wandering stars in the local universe: Theoretical predictions for their distance and luminosity distribution. ApJ, 990(1), 58. (www)

  @article{ , abstract = {Intergalactic wandering stars (IWSs) within 10 Mpc remain a poorly explored area of astronomy. Such stars, if they exist, are supposed to be wandering objects as they are not bound by the gravitational potential of any galaxy. We set out to conduct dedicated studies to unravel such a wandering stellar population. As the first paper of the series, in the present work, we model the distance distribution and luminosity function of IWSs formed via the Hills mechanism of the Galactic central massive black hole (GCMBH). We implement a numerical simulation to generate IWSs, taking the ejection history of the GCMBH and the stellar evolution process into consideration, and present their luminosity function in the distance range of 200 kpc–10 Mpc. Our results suggest that a few hundred thousand IWSs have been generated by the GCMBH via the Hills mechanism in the past 14 billion yr. These IWSs have an apparent magnitude peaking at 30–35 mag in the Sloan Digital Sky Survey r band, which are hard to detect. However, a few thousand of them at the bright end are detectable by upcoming wide-field deep surveys, such as the China Space Station Telescope and the Vera Rubin Observatory. The forthcoming discovery of such a wandering stellar population will open the door for a precise understanding of the matter constitution of the nearby intergalactic space and the dynamical history of galaxies in the local Universe.}, archive = {J_ApJ}, author = {Jia-Hui Wang and Maosheng Xiang and Ji-Feng Liu}, doi = {10.3847/1538-4357/adf8c8}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {58}, shortjournal = {The Astrophys. J.}, title = {Intergalactic wandering stars in the local universe: Theoretical predictions for their distance and luminosity distribution}, volume = {990}, year = {2025}, }
• (2025). JWST discovery of warm dust in the circumgalactic medium of the makani galaxy. ApJ, 990(1), 57. (www)

  @article{ , abstract = {We report the detection of near- and mid-infrared emission from polycyclic aromatic hydrocarbons (PAHs) out to ∼35 kpc in the Makani Galaxy, a compact massive galaxy with a record-breaking 100 kpc scale starburst-driven wind at redshift z = 0.459. The NIRCam and MIRI observations with JWST take advantage of a coincidental match between the PAH spectral features at 3.3, 7.7, and (11.3 + 12.2) μ m in Makani and the bandpasses of the MIRI and NIRCam filters. The warm dust is not only detected in the cool-gas tracers of the galactic wind associated with the more recent (7 Myr) starburst episode, but also in the outer warm ionized gas wind produced by the older (0.4 Gyr) episode. The presence of PAHs in the outer wind indicates that the PAHs have survived the long ( R / v ∼ 10 8 yr) journey to the halo despite the harsh environment of the galactic wind. The measured F1800W/F1130W flux ratios in the unresolved nucleus, inner halo ( R = 10–20 kpc), and outer halo ( R = 20–35 kpc), tracers of the PAH (11.3 + 12.2)/7.7 ratios, indicate decreasing starlight intensity incident on the PAHs, decreasing PAH sizes, and increasing PAH ionization fractions with increasing distance from the nucleus. These data provide the strongest evidence to date that the ejected dust of galactic winds survives the long journey to the circumgalactic medium, but is eroded along the way.}, archive = {J_ApJ}, author = {Sylvain Veilleux and Steven D. Shockley and Marcio Meléndez and David S. N. Rupke and Alison L. Coil and Aleksandar M. Diamond-Stanic and James E. Geach and Ryan C. Hickox and John Moustakas and Gregory H. Rudnick and Paul H. Sell and Christy A. Tremonti and Hojoon Cha}, doi = {10.3847/1538-4357/adee91}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {57}, shortjournal = {The Astrophys. J.}, title = {JWST discovery of warm dust in the circumgalactic medium of the makani galaxy}, volume = {990}, year = {2025}, }
• (2025). Mapping ground-based coronagraphic images to helioprojective-cartesian coordinate system by image registration. ApJ, 990(1), 56. (www)

  @article{ , abstract = {A few ground-based solar coronagraphs have been installed in western China for observing the low-layer corona in recent years. However, determining the helioprojective coordinates for the coronagraphic data with high precision is an important but challenging step for further research with other multiwavelength data. In this paper, we propose an automatic coronal image registration method that combines local statistical correlation and feature point matching to achieve accurate registration between ground-based coronal green-line images and space-based 211 Å images. Then, the accurate field of view information of the coronal green-line images can be derived, allowing the images to be mapped to the helioprojective Cartesian coordinates with an accuracy of no less than 0\mathop{.}\limits{^{\prime\prime} }1 . This method has been extensively validated using 100 days of coronal data spanning an 11 yr period, demonstrating its broad applicability to ground-based coronagraphs equipped with green-line observations. It significantly enhances the scientific value of ground-based coronal data, enabling comprehensive studies of coronal transient activities and facilitating the joint analysis of data from multiple instruments. Additionally, it holds potential for future applications in improving the pointing accuracy of coronagraphs.}, archive = {J_ApJ}, author = {Feiyang Sha and Yu Liu and Lidong Xia and Yao Chen and Qing Zhou and Yangrui Chen and Chuyu Zhong and Xuefei Zhang and Tengfei Song and Mingzhe Sun and Xiaoyu Yu and Haitang Li and Jacob Oloketuyi and Qiang Liu and Xinjian Wang and Qiwang Luo and Xiaobo Li}, doi = {10.3847/1538-4357/adf05e}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {56}, shortjournal = {The Astrophys. J.}, title = {Mapping ground-based coronagraphic images to helioprojective-cartesian coordinate system by image registration}, volume = {990}, year = {2025}, }
• (2025). Impact of radio-mode feedback on the covering fraction of the circumgalactic medium of quasars. ApJ, 990(1), 55. (www)

  @article{ , abstract = {Utilizing data from the Low-Frequency Array Two-meter Sky Survey and the Sloan Digital Sky Survey, we assemble a sample of 1469 projected quasar pairs with detected radio emissions from foreground quasars, as well as a control sample of 5846 pairs without detected radio emission, with the aim being to assess the impact of radio-mode feedback from quasars on the characteristics of the circumgalactic medium (CGM). By analyzing transverse Mg ii absorption lines associated with foreground quasars in the spectra of background quasars, we observe that the Mg ii covering fraction ( f c ) for quasars with detected radio emissions is significantly higher (∼3 σ ) than those without radio detections at projected distances d p ≤ 100 kpc, while no significant differences are noted on larger scales. Furtherly, if we remove the radio-quiet quasars from our sample, we find that this discrepancy between radio-loud quasars and the control group becomes even more significant. However, at larger projected distances, all types of quasars tend to have similar covering fractions. These findings suggest that radio-mode feedback from quasars may substantially influence the properties of the CGM on specific scales, particularly as quasars with radio emissions possess more powerful jets, enabling them to expel gas more effectively across various scales. This study offers new insights into the role of radio-mode feedback in galaxy evolution and underscores the importance of jets in regulating the gas distribution within the CGM.}, archive = {J_ApJ}, author = {Wen-Qiang Liang and Zhi-fu Chen and Rui-Jing Lu and Jing Li and Zhe-Geng Chen}, doi = {10.3847/1538-4357/adf32f}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {55}, shortjournal = {The Astrophys. J.}, title = {Impact of radio-mode feedback on the covering fraction of the circumgalactic medium of quasars}, volume = {990}, year = {2025}, }
• (2025). The small separation A-star companion population: Tentative signatures of enhanced multiplicity with primary mass. ApJ, 990(1), 54. (www)

  @article{ , abstract = {We present updated results from our near-infrared long-baseline interferometry (LBI) survey to constrain the multiplicity properties of intermediate-mass A-type stars within 80 pc. Previous adaptive optics surveys of A-type stars are incomplete at separations <20 au. Therefore, an LBI survey allows us to explore separations previously unexplored. Our sample consists of 54 A-type primaries with estimated masses between 1.44 and 2.93 M ⊙ and ages 10–790 Myr, which we observed with the Michigan Infra-Red Combiner-eXeter and Michigan Young Star Imager at Center for High Angular Resolution Astronomy instruments at the Center for High Angular Resolution Astronomy Array. We use the open source software CANDID to detect two new companions, seven in total, and we performed a Bayesian demographic analysis to characterize the companion population. We find the separation distribution consistent with being flat, and we estimate a power-law fit to the mass ratio distribution with index –0.13 {}_{-0.95}^{+0.92} and a companion frequency of 0.25 {}_{-0.11}^{+0.17} over mass ratios 0.1–1.0 and projected separations 0.01–27.54 au. We find a posterior probability of 0.53 and 0.04 that our results are consistent with extrapolations based on previous models of the solar-type and B-type companion population, respectively. Our results suggest that the close companion population to A-type stars is comparable to that of solar-type stars and that close companions to B-type stars are potentially more frequent, which may be indicative of increased disk fragmentation for stars ≳3 M ⊙ .}, archive = {J_ApJ}, author = {Matthew De Furio and Tyler Gardner and John D. Monnier and Michael R. Meyer and Kaitlin M. Kratter and Cyprien Lanthermann and Narsireddy Anugu and Stefan Kraus and Benjamin R. Setterholm}, doi = {10.3847/1538-4357/adf3b1}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {54}, shortjournal = {The Astrophys. J.}, title = {The small separation A-star companion population: Tentative signatures of enhanced multiplicity with primary mass}, volume = {990}, year = {2025}, }
• (2025). The dynamics of infall and accretion shocks in the outer disk. ApJ, 990(1), 53. (www)

  @article{ , abstract = {High-spatial-resolution observations of disks around young stars suggest planetary systems begin forming early, during the protostellar phase (≤1 Myr) when stars accrete most of their mass via infall from the surrounding cloud. During this era, shocks are expected to be ubiquitous around the gaseous accretion disk, due to supersonic infall that strikes the disk. We investigate the role of shocks using a theoretical and modeling framework we call the shock twist-angle Keplerian (STAK) disk, connecting the disk and infalling envelope gas via a shock using general physical principles. Briefly, at the shock, energy is dissipated while angular momentum is conserved, so that the infalling gas must change direction sharply, yielding a bend or twist in the streamlines. The model’s pre-shock gas follows freefall parabolic trajectories, while the post-shock gas is on lower-energy, elliptical orbits. We construct synthetic observations and find that the deviations from circular Keplerian orbits are detectable in Doppler-shifted molecular spectral lines using radio interferometers such as ALMA. Specifically, the STAK model leads to line emission intensity and velocity-moment maps that are asymmetric and offset with respect to the disk structure traced by the dust continuum. We examine archival ALMA data for the class 0/I protostar L1527 and find the C 18 O velocity moment map has features resembling the disk-plus-envelope emissions that naturally arise when the two are connected by a shock. Thus, spectral line observations having sub-km s −1 spectral resolution and angular resolution sufficient to fully resolve the disk can reveal protostars’ envelope-disk shocks.}, archive = {J_ApJ}, author = {Susan Terebey and Loraine Sandoval Ascencio and Lizxandra Flores-Rivera and Neal J. Turner and Andrew Barajas}, doi = {10.3847/1538-4357/ade3c6}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {53}, shortjournal = {The Astrophys. J.}, title = {The dynamics of infall and accretion shocks in the outer disk}, volume = {990}, year = {2025}, }
• (2025). A new determination of the mass of NGC 3603-a1: The most massive binary known?. ApJ, 990(1), 52. (www)

  @article{ , abstract = {The star NGC 3603-A1 has long been known to be a very massive binary, consisting of a pair of O2-3If*/WN5-6 stars which show Wolf–Rayet–like emission due to their luminosities being near the Eddington limit. The system has been poorly characterized until now, due to the difficulties of obtaining reliable radial velocities from broad, blended emission lines and the extreme crowding in the cluster. However, previously unpublished archival Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS) spectra revealed that some of the upper Balmer lines (seen in absorption) are well separated at favorable orbital phases, prompting us to obtain our own carefully timed new HST/STIS spectra, which we have analyzed along with the older data. Radial velocities measured from these spectra allow us to obtain an orbit for this 3.77298-day binary. We also used archival STIS imaging of the cluster to obtain a more accurate light curve for this eclipsing system, which we then modeled, yielding the orbital inclination and providing values for the stellar radii and temperatures. Together, these data show that the NGC 3603-A1 system consists of a 93.3 ± 11.0 M ⊙ O3If*/WN6 primary with an effective temperature of 37,000 K, and a 70.4 ± 9.3 M ⊙ O3If*/WN5 secondary that is slightly hotter, 42,000 K. Although a more massive binary is known in the LMC, NGC 3603-A1 is as massive as any binary known in our own Galaxy for which a direct measurement of its mass has been made by a fundamental method. The secondary has been spun up by mass accretion from the primary, and we discuss the evolutionary status of this intriguing system.}, archive = {J_ApJ}, author = {Philip Massey and Sarah Bodansky and Laura R. Penny and Nidia I. Morrell and Kathryn F. Neugent}, doi = {10.3847/1538-4357/ade799}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {52}, shortjournal = {The Astrophys. J.}, title = {A new determination of the mass of NGC 3603-a1: The most massive binary known?}, volume = {990}, year = {2025}, }
• (2025). Spatially resolved kinematics of SLACS lens galaxies. i. data and kinematic classification. ApJ, 990(1), 51. (www)

  @article{ , abstract = {We obtain spatially resolved kinematics with the Keck Cosmic Web Imager (KCWI) integral-field spectrograph for a sample of 14 massive ( 11\lt {\mathrm{log}}_{10}{M}_{* }/{M}_{\odot }\lt 12 ) lensing early-type galaxies at z ∼ 0.15–0.35 from the Sloan Lens ACS (SLACS) Survey. We integrate kinematic maps within the galaxy effective radius and examine the rotational and dispersion velocities, showing that 11/14 can be classified as slow rotators. The data set is unprecedented for galaxy-scale strong lenses in terms of signal-to-noise ratio (S/N), sampling, and calibration, vastly superseding previous studies. We find the primary contributions to systematic uncertainties to be the stellar template library and wavelength range of the spectral fit. Systematics are at the 1%–1.4% level, and positive covariance is <1% between sample galaxies and between spatial bins. This enables cosmographic inference with lensing time delays with a <2% uncertainty on H 0 . We examine the effects of integration of the data cubes within circular apertures of different sizes and compare with Sloan Digital Sky Survey (SDSS) single-aperture velocity dispersions. We conclude that the velocity dispersions extracted from SDSS spectra for these 14 SLACS galaxies, which have low S/N (∼9 Å –1 ) relative to the SLACS candidate parent sample, are subject to systematic errors (and covariance) due to stellar template library selection at the level of 3% (2%), which need to be added to the random errors. Comparison between our KCWI stellar velocity dispersions, our own analysis of SDSS spectra, and previously published measurements based on SDSS spectra shows mean differences within a few percent. However, these differences are not significant given the uncertainties of the SDSS-based stellar velocity dispersions. We find that the correlations between scaling relations using quantities inferred from dynamical, lensing, and stellar population models agree with previous SLACS analysis with no statistically significant change. A follow-up paper will present Jeans modeling in the context of broader studies of galaxy evolution and cosmology.}, archive = {J_ApJ}, author = {Shawn Knabel and Tommaso Treu and Michele Cappellari and Anowar J. Shajib and Chih-Fan Chen and Simon Birrer and Vardha N. Bennert}, doi = {10.3847/1538-4357/adea94}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {51}, shortjournal = {The Astrophys. J.}, title = {Spatially resolved kinematics of SLACS lens galaxies. i. data and kinematic classification}, volume = {990}, year = {2025}, }
• (2025). CHIME all-sky multiday pulsar stacking search (CHAMPSS): System overview and first discoveries. ApJ, 990(1), 50. (www)

  @article{ , abstract = {We describe the Canadian Hydrogen Intensity Mapping Experiment (CHIME) All-sky Multiday Pulsar Stacking Search (CHAMPSS) project. This novel radio pulsar survey revisits the full northern sky daily, offering unprecedented opportunity to detect highly intermittent pulsars, as well as faint sources via long-term data stacking. CHAMPSS uses the CHIME/FRB datastream, which consists of 1024 stationary beams streaming intensity data at 0.983 ms resolution, with 16,384 frequency channels across 400–800 MHz, continuously being searched for single, dispersed bursts/pulses. In CHAMPSS, data from adjacent east–west beams are combined to form a grid of tracking beams, allowing longer exposures at fixed positions. These tracking beams are dedispersed to many trial dispersion measures (DM) to a maximum DM beyond the Milky Way’s expected contribution, and Fourier transformed in time to form power spectra. Repeated observations are searched daily to find intermittent sources, and power spectra of the same sky positions are incoherently stacked, increasing sensitivity to faint persistent sources. The 0.983 ms time resolution limits our sensitivity to millisecond pulsars; we have full sensitivity to pulsars with P > 60 ms, with sensitivity gradually decreasing from 60 ms to 2 ms, as higher harmonics are beyond the Nyquist limit. In a commissioning survey, data covering ∼1/16 of the CHIME sky were processed and searched in quasi-realtime over two months, leading to the discovery of 11 new pulsars, each with S 600 > 0.1 mJy. When operating at scale, CHAMPSS will stack >1 yr of data along each sightline, reaching a sensitivity of ≲30 μ Jy for all sightlines above a decl. of 10°, and off of the Galactic plane.}, archive = {J_ApJ}, author = {Christopher Andrade and P. J. Boyle and Charanjot Brar and Alyssa Cassity and Kathryn Crowter and Davor Cubranic and Abigail K. Denney and Fengqiu Adam Dong and Emmanuel Fonseca and Victoria M. Kaspi and Ajay Kumar and Lars Künkel and Magnus L’Argent and Dustin Lang and Robert A. Main and Kiyoshi W. Masui and Sujay Mate and Juan Mena-Parra and Bradley W. Meyers and Cherry Ng and Aaron B. Pearlman and Ue-Li Pen and Scott M. Ransom and Alexander P. Roman and Kendrick Smith and Reynier Squillace and Ingrid Stairs and Chia Min Tan and Laurent Tarabout and Wenke Xia and Tarik J. Zegmott and (The CHAMPSS Collaboration)}, doi = {10.3847/1538-4357/adeb51}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {50}, shortjournal = {The Astrophys. J.}, title = {CHIME all-sky multiday pulsar stacking search (CHAMPSS): System overview and first discoveries}, volume = {990}, year = {2025}, }
• (2025). Evolution of supernova remnants in a cloudy multiphase interstellar medium. ApJ, 990(1), 49. (www)

  @article{ , abstract = {We investigate the evolution of supernova remnants (SNRs) in a two-phase cloudy medium by performing a series of high-resolution (up to Δ x ≈  0.01 pc), 3D hydrodynamical simulations including radiative cooling and thermal conduction. We aim to reach a resolution that directly captures the shock–cloud interactions for the majority of the clouds initialized by the saturation of thermal instability. In comparison to the SNR in a uniform medium with the volume filling warm medium, the SNR expands similarly (following ∝ t 2/5 ) but sweeps up more mass as the cold clouds contribute before shocks in the warm medium become radiative. However, the SNR in a cloudy medium continuously loses energy after shocks toward the cold clouds cool, resulting in less hot gas mass, thermal energy, and terminal momentum. Thermal conduction has little effect on the dynamics of the SNR but smooths the morphology and modifies the internal structure by increasing the density of hot gas by a factor of ∼3–5. The simulation results are not fully consistent with many previous 1D models describing the SNR in a cloudy medium, including a mass loading term. By direct measurement in the simulations, we find that, apart from the mass source, the energy sink is also important with a spatially flat cooling rate \dot{e}\propto {t}^{-11/5} . As an illustration, we show an example 1D model including both mass source and energy sink terms (in addition to the radiative cooling in the volume filling component) that better describes the structure of the simulated SNR.}, archive = {J_ApJ}, author = {Minghao Guo and Chang-Goo Kim and James M. Stone}, doi = {10.3847/1538-4357/adeb85}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {49}, shortjournal = {The Astrophys. J.}, title = {Evolution of supernova remnants in a cloudy multiphase interstellar medium}, volume = {990}, year = {2025}, }
• (2025). Detecting land with reflected-light spectroscopy to rule out waterworld o2 biosignature false positives. ApJ, 990(1), 48. (www)

  @article{ , abstract = {The search for life outside our solar system is at the forefront of modern astronomy, and telescopes such as the Habitable Worlds Observatory (HWO) are being designed to identify biosignatures. Molecular oxygen, O 2 , is considered a promising indication of life, yet substantial abiotic O 2 may accumulate from H 2 O photolysis and hydrogen escape on a lifeless, fully (100%) ocean-covered terrestrial planet when surface O 2 sinks are suppressed. This so-called waterworld false-positive scenario could be ruled out with land detection because exposed land precludes extremely deep oceans (∼50 Earth oceans) given topographic limits set by the crushing strength of rocks. Land detection is possible because plausible geologic surfaces exhibit increasing reflectance with wavelength in the visible, whereas liquid water and ice/snow have flat or decreasing reflectance, respectively. Here, we present reflected-light retrievals to demonstrate that HWO could detect land on an exo-Earth in the disk-averaged spectrum. Given a signal-to-noise ratio (SNR) of 20 spectrum, Earth-like land fractions can be confidently detected with 0.3–1.1 μ m spectral coverage (resolution R ∼ 140 in the visible, R ∼ 7 in the UV, with Earth-like atmosphere and clouds). We emphasize the need for UV spectroscopy down to at least 0.3 μ m to break an O 3 –land degeneracy. We find that the SNR and resolution requirements in the visible/UV imply a large aperture (∼8 m) will be necessary to ensure the observing times required for land detection are feasible for most HWO terrestrial habitable zone targets. These results strongly inform the HWO minimum requirements to corroborate possible oxygen biosignatures.}, archive = {J_ApJ}, author = {Anna Grace Ulses and Joshua Krissansen-Totton and Tyler D. Robinson and Victoria Meadows and David C. Catling and Jonathan J. Fortney}, doi = {10.3847/1538-4357/adec69}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {48}, shortjournal = {The Astrophys. J.}, title = {Detecting land with reflected-light spectroscopy to rule out waterworld o2 biosignature false positives}, volume = {990}, year = {2025}, }
• (2025). Domain adaptation in application to gravitational lens finding. ApJ, 990(1), 47. (www)

  @article{ , abstract = {The next decade is expected to see a tenfold increase in the number of strong gravitational lenses, driven by new wide-field imaging surveys. To discover these rare objects, efficient automated detection methods need to be developed. In this work, we assess the performance of three domain adaptation (DA) techniques—adversarial discriminative DA, Wasserstein distance guided representation learning (WDGRL), and supervised domain adaptation (SDA)—in enhancing lens-finding algorithms trained on simulated data when applied to observations from the Hyper Suprime-Cam Subaru Strategic Program. We find that WDGRL combined with an equivariant-neural-network-based encoder provides the best performance in an unsupervised setting and that SDA is able to enhance the model’s ability to distinguish between lenses and common similar-looking false positives, such as spiral galaxies, which is crucial for future lens surveys.}, archive = {J_ApJ}, author = {Hanna Parul and Sergei Gleyzer and Pranath Reddy and Michael W. Toomey}, doi = {10.3847/1538-4357/adee16}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {47}, shortjournal = {The Astrophys. J.}, title = {Domain adaptation in application to gravitational lens finding}, volume = {990}, year = {2025}, }
• (2025). The host galaxies of pulsar timing array sources: Converting supermassive black hole binary parameters into electromagnetic observables. ApJ, 990(1), 46. (www)

  @article{ , abstract = {Pulsar timing arrays (PTAs) are approaching the sensitivity required to resolve gravitational waves (GWs) from individual supermassive black hole (SMBH) binaries. However, the large uncertainty in source localization will make the identification of its host environment challenging. We show how to convert the posterior probability function of binary parameters inferred by GW analyses into distributions of apparent magnitudes of the host galaxy. We do so for a scenario in which the host environment is a regular early-type galaxy, and one in which it is an active galactic nucleus. We estimate the reach of PTAs in the near and intermediate future, and estimate whether the binary hosts will be detectable in all-sky electromagnetic (EM) surveys. A PTA with a baseline of 20 yr and 116 pulsars, resembling the upcoming data release of the International Pulsar Timing Array, can detect binaries out to a luminosity distance of 2 Gpc (corresponding to a redshift of z ∼ 0.36), while a PTA with a baseline of 30 yr and 200 pulsars can reach out to distances slightly greater than 3 Gpc ( z ∼ 0.53). We find that the host galaxies of all binaries detectable with a baseline of 20 yr are expected to be present in the Wide-field Infrared Survey Explorer and SuperCOSMOS surveys, if they lie outside the plane of the Milky Way. The Two Micron All Sky Survey becomes incomplete for hosts of binaries more massive than 10 9.8 M ⊙ at a luminosity distance greater than 1 Gpc. The EM surveys become slightly more incomplete when PTAs with longer baselines and therefore improved sensitivities are considered.}, archive = {J_ApJ}, author = {Niccolò Veronesi and Maria Charisi and Stephen R. Taylor and Jessie Runnoe and Daniel J. D’Orazio}, doi = {10.3847/1538-4357/adf065}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {46}, shortjournal = {The Astrophys. J.}, title = {The host galaxies of pulsar timing array sources: Converting supermassive black hole binary parameters into electromagnetic observables}, volume = {990}, year = {2025}, }
• (2025). Current helicity in response to coronal mass ejections. ApJ, 990(1), 45. (www)

  @article{ , abstract = {Coronal mass ejections (CMEs), powerful solar eruptions with massive plasma ejected into the interplanetary space, are caused by the release of the magnetic free energy stored in coronal electric currents. Photospheric current helicity, defined as the integral of the product of the vertical electric current density and vertical magnetic field ( H c = ∫ j z B z dS ), serves as a key parameter in understanding the eruptions. Using a 3D magnetohydrodynamic model, we identified a current helicity reversal pattern associated with the eruption: a pre-eruption decrease and a post-eruption increase. This helicity reversal is attributed to the redistribution of electric currents: before the eruption, currents concentrate toward the polarity inversion line (PIL); after the eruption they move away from the PIL, consistent with flare ribbon separation, which is caused by the upward progression of the reconnection site. To validate this pattern, we conducted an observational analysis of 50 ≥M5.0 eruptive flares. The results reveal that 58% of cases exhibit a pre-eruption decrease and 92% show a post-eruption increase in current helicity. Detailed analysis of two cases with this reversal suggests that they share the same current redistribution pattern, consistent with the mechanism identified in the simulations. Moreover, a pre-eruption decrease could be observed clearly even in the long-term evolution of the two cases. Current helicity can serve as an indicator of when electric currents are built up for the subsequent eruption, and it has the potential to predict CMEs to some extent.}, archive = {J_ApJ}, author = {Zheng Sun and Ting Li and Xinkai Bian and Yijun Hou and Ioannis Kontogiannis and Ziqi Wu}, doi = {10.3847/1538-4357/adf18b}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {45}, shortjournal = {The Astrophys. J.}, title = {Current helicity in response to coronal mass ejections}, volume = {990}, year = {2025}, }
• (2025). Self-consistent JWST census of star formation and AGN activity at z = 5.5–13.5. ApJ, 990(1), 44. (www)

  @article{ , abstract = {The cosmic star formation history (CSFH) and cosmic active galactic nuclei (AGN) luminosity history (CAGNH) are self consistently measured at z = 5.5–13.5. This is achieved by analyzing galaxies detected by the James Webb Space Telescope from \approx 400\,{{\rm{arcmin}}}^{2} fields from the Prime Extragalactic Areas of Reionization and Lensing Science, Cosmic Evolution Early Release Science, Next Generation Deep Extragalactic Exploratory Public, JWST Advanced Deep Extragalactic Survey, and Public Release IMaging for Extragalactic Research surveys. In particular, the combination of spectral energy distribution fitting codes, EAZY and ProSpect , is employed to estimate the photometric redshifts and astrophysical quantities of 3751 distant galaxies, from which we compute the stellar mass, star formation rate, and AGN luminosity distribution functions in four redshift bins. Integrating the distribution functions, we find that the CSFH rises by ≈1 dex over z = 13.5–5.5, and the CAGNH rises by ≈1 dex over z = 10.5–5.5. We connect our results of the CSFH and CAGNH at z = 13.5–5.5 to that from z = 5–0 to determine the summary of ≳13 Gyr of star formation and AGN activity, from the very onset of galaxy formation to the present day.}, archive = {J_ApJ}, author = {Jordan C. J. D’Silva and Simon P. Driver and Claudia D. P. Lagos and Aaron S. G. Robotham and Nathan J. Adams and Christopher J. Conselice and Brenda Frye and Nimish P. Hathi and Thomas Harvey and Anton M. Koekemoer and Rafael Ortiz and Massimo Ricotti and Clayton Robertson and Michael J. Rutkowski and Ross M. Silver and Stephen M. Wilkins and Christopher N. A. Willmer and Rogier A. Windhorst and Seth H. Cohen and Rolf A. Jansen and Jake Summers and Dan Coe and Norman A. Grogin and Madeline A. Marshall and Mario Nonino and Nor Pirzkal and Russell E. Ryan and Haojing Yan}, doi = {10.3847/1538-4357/adf19e}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {44}, shortjournal = {The Astrophys. J.}, title = {Self-consistent JWST census of star formation and AGN activity at z = 5.5–13.5}, volume = {990}, year = {2025}, }
• (2025). A hidden pulse: Uncovering a new timing signal in cygnus X-1 with AstroSat. ApJ, 990(1), 43. (www)

  @article{ , abstract = {The study of fast variability properties in X-ray binaries advances our understanding of the physical processes and geometric properties of the accretion flow around the compact object. In this work, we study the evolution of the timing properties of Cygnus X-1 with AstroSat/LAXPC, during the transition of the source from the hard to soft state in 2017. We use a novel frequency-segmented technique to fit simultaneously the cross spectra and parts of the power spectra and coherence function with a multi-Lorentzian model and predict the phase lags and the complementary parts of the power spectra and coherence function. We study the evolution of the frequency and power of the main variability components that are present throughout all the states. In particular, we identify previously undetected variability components, one of which manifests as a narrow dip in the coherence function and a broad drop in the phase-lag spectrum at the same frequency. This dip in coherence, which we detect for the first time in Cygnus X-1 at energies above 3 keV, appears in a state in which the source shows high-amplitude radio variability and significant hard X-ray polarization. While the contribution of the compact jet in X-rays is debated in the literature, this study provides a new avenue for investigating jet properties as well as the geometry of the Comptonizing medium.}, archive = {J_ApJ}, author = {Sandeep K. Rout and Federico García and Mariano Méndez and Abhay Kumar and Santosh Vadawale and David M. Russell and Pei Jin}, doi = {10.3847/1538-4357/adf1a5}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {43}, shortjournal = {The Astrophys. J.}, title = {A hidden pulse: Uncovering a new timing signal in cygnus X-1 with AstroSat}, volume = {990}, year = {2025}, }
• (2025). XRISM constrains atmospheric motion and turbulent dissipation in the archetypal radio-mode feedback system hydra-A. ApJ, 990(1), 42. (www)

  @article{ , abstract = {We present XRISM Resolve observations centered on Hydra-A, a redshift z = 0.054 brightest cluster galaxy, which hosts one of the largest and most powerful FR-I radio sources in the nearby Universe. We examine the effects of its high jet power on the velocity structure of the cluster’s hot atmosphere. Hydra-A’s central radio jets have inflated X-ray cavities with energies upward of 10 61 erg. They reach altitudes of 225 kpc from the cluster center, well beyond the atmosphere’s central cooling region. Resolve’s 3′× 3′ field of view covers 190 × 190 kpc, which encompasses most of the cooling volume. We find a one-dimensional atmospheric velocity dispersion across the volume of 164 ± 10 km s −1 . The fraction in isotropic turbulence or unresolved bulk velocity is unknown. Assuming pure isotropic turbulence, the turbulent kinetic energy is 2.5% of the thermal energy radiated away over the cooling timescale, implying that kinetic energy must be supplied continually to offset cooling. While Hydra-A’s radio jets are powerful enough to supply kinetic energy to the atmosphere at the observed level, turbulent dissipation alone would struggle to offset cooling throughout the cooling volume. The central galaxy’s radial velocity is similar to the atmospheric velocity, with an offset of −37 ± 23 km s −1 .}, archive = {J_ApJ}, author = {Tom Rose and B. R. McNamara and Julian Meunier and A. C. Fabian and Helen Russell and Paul Nulsen and Neo Dizdar and Timothy M. Heckman and Michael McDonald and Maxim Markevitch and Frits Paerels and Aurora Simionescu and Norbert Werner and Alison L. Coil and Edmund Hodges-Kluck and Eric D. Miller and Michael Wise}, doi = {10.3847/1538-4357/adf32d}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {42}, shortjournal = {The Astrophys. J.}, title = {XRISM constrains atmospheric motion and turbulent dissipation in the archetypal radio-mode feedback system hydra-A}, volume = {990}, year = {2025}, }
• (2025). Introducing STARDIS: An open and modular stellar spectral synthesis code. ApJ, 990(1), 41. (www)

  @article{ , abstract = {We introduce a new 1D stellar spectral synthesis Python code called stardis . stardis is a modular, open-source radiative transfer code that is capable of spectral synthesis from near-UV to IR for FGK stars. We describe the structure, inputs, features, underlying physics, and assumptions of stardis , as well as the radiative transfer scheme implemented. To validate our code, we show spectral comparisons between stardis and korg with the same input atmospheric structure models, and we also compare qualitatively to phoenix for solar models. We find that stardis generally agrees with korg for solar models on the few-percent level or better, though the codes can diverge in the UV, with more extreme differences in cooler stars. stardis can be found at https://github.com/tardis-sn/stardis , and documentation can be found at https://tardis-sn.github.io/stardis/ .}, archive = {J_ApJ}, author = {Joshua V. Shields and Wolfgang Kerzendorf and Isaac G. Smith and Tiago M. D. Pereira and Christian Vogl and Ryan Groneck and Andrew G. Fullard and Jaladh Singhal and Jing Lu and Christopher J. Fontes}, doi = {10.3847/1538-4357/adee11}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {41}, shortjournal = {The Astrophys. J.}, title = {Introducing STARDIS: An open and modular stellar spectral synthesis code}, volume = {990}, year = {2025}, }
• (2025). B-fields and dust in interstellar filaments using dust polarization (BALLAD-POL). IV. grain alignment mechanisms in the cocoon nebula (IC 5146) using polarization observations from JCMT/POL-2. ApJ, 990(1), 40. (www)

  @article{ , abstract = {The polarization of starlight and thermal dust emission from aligned nonspherical grains provides a powerful tool for tracing magnetic field morphologies and strengths in the diffuse interstellar medium to star-forming regions, and constraining the properties of dust grains and their alignment mechanisms. However, the physics of grain alignment is not yet fully understood. The alignment based on radiative torques (RATs), known as RAT alignment or the RAT-A mechanism, is the most acceptable mechanism. In this work, we investigate the grain alignment mechanisms in the F13 (F13N and F13C) and F13S filamentary regions of the Cocoon Nebula (IC 5146) using observations of polarized thermal dust emission from James Clerk Maxwell Telescope/POL-2 at 850 μ m. We find that the polarization fraction decreases with increasing total intensity and gas column density in each region, termed a polarization hole. We investigate any role of magnetic field tangling in the observed polarization hole by estimating the polarization angle dispersion function. Our study finds that the polarization hole is not significantly influenced by magnetic field tangling, but is mainly due to the decrease in RAT alignment efficiency of grains in denser regions. To test whether the RAT-A mechanism can reproduce the observed results, we estimate the minimum alignment size of grains using RAT theory. Our study finds strong evidence for the RAT-A mechanism that can explain the polarization hole. We also find potential hints that the observed higher polarization fractions in some regions of the F13 filament can be due to the combined effects of both suprathermal rotation by RATs and enhanced magnetic relaxation, supporting the magnetically enhanced RAT mechanism.}, archive = {J_ApJ}, author = {Saikhom Pravash and Thiem Hoang and Archana Soam and Eun Jung Chung and Diep Ngoc Pham and Nguyen Bich Ngoc and Le Ngoc Tram}, doi = {10.3847/1538-4357/adef09}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {40}, shortjournal = {The Astrophys. J.}, title = {B-fields and dust in interstellar filaments using dust polarization (BALLAD-POL). IV. grain alignment mechanisms in the cocoon nebula (IC 5146) using polarization observations from JCMT/POL-2}, volume = {990}, year = {2025}, }
• (2025). Turbulence inhibits planetesimal formation in class 0/I disks subject to infall. ApJ, 990(1), 39. (www)

  @article{ , abstract = {There is growing evidence that planet formation begins early, within the ≲1 Myr Class 0/I phase, when infall dominates disk dynamics. Our goal is to determine if Class 0/I disks reach the conditions needed to form planetesimals (∼100 km planet building blocks) by the streaming instability (SI). We focus on a recent suggestion that early infall causes an “inflationary” phase in which dust grains are advected outward. We modified the DustPy code to build a 1D disk that includes dust evolution, infall, and heating and cooling sources. We ran six models and examined the implications for the SI, taking into account recent works on how the SI responds to external turbulence. In line with other works, we find that grains are advected outward, which leads to an “advection-condensation-drift” loop that greatly enhances the dust density at the water snowline. However, we do not see this process at the silicate line. Instead, we find a new pile up at the edge of the expanding disk. However, despite these localized enhancements, even a modest amount of turbulence ( α = 10 −3 ) leaves planetesimal formation far out of reach. The midplane dust-to-gas ratio is at least an order of magnitude below the SI threshold, even taking into account recent results on how dust coagulation boosts the SI. For planetesimals to form in the Class 0/I phase may require a way to transport angular momentum without turbulence (e.g., disk winds) or a non-SI mechanism to form planetesimals.}, archive = {J_ApJ}, author = {Daniel Carrera and Abigail Davenport and Jacob B. Simon and Hans Baehr and Til Birnstiel and Cassandra Hall and David Rea and Sebastian Markus Stammler}, doi = {10.3847/1538-4357/adef46}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {39}, shortjournal = {The Astrophys. J.}, title = {Turbulence inhibits planetesimal formation in class 0/I disks subject to infall}, volume = {990}, year = {2025}, }
• (2025). Rossby number regime, convection suppression, and dynamo-generated magnetism in inflated hot jupiters. ApJ, 990(1), 38. (www)

  @article{ , abstract = {Hot Jupiters (HJs) are commonly thought to host the strongest dynamo-generated magnetic fields among exoplanets, up to 1 order of magnitude larger than Jupiter. Thus, they have often been regarded as the most promising exoplanets to display magnetic star–planet interaction signals and magnetically driven coherent radio emission, which unfortunately remains elusive, despite many diversified observational campaigns. In this work, we investigate the evolution of the internal convection and dynamo properties of HJs via one-dimensional models. We explore the dependency on orbital distance, planetary and stellar masses, and types of heat injection. We employ one-dimensional evolutionary models to obtain internal convective structures. Specifically, we obtain the Rossby number Ro as a function of planetary depth and orbital period, after showing that tidal synchronization is likely valid for all HJs. When the heat is applied uniformly, the convective layers of almost all HJs remain in the fast rotator regime, Ro ≲ 0.1, except possibly the most massive planets with large orbital distances (but still tidally locked). We recover magnetic field strengths for inflated HJs by applying well-known scaling laws for fast rotators. When strong heat sources are applied mostly in the outer envelope and outside the dynamo region, as realistic ohmic models predict, convection in the dynamo region often breaks down. Consequently, the heat flux and the derived surface magnetic fields can be greatly reduced to or below Jovian values, contrary to what is commonly assumed, thus negatively affecting estimates for coherent radio emission, and possibly explaining the failure in detecting it so far.}, archive = {J_ApJ}, author = {Albert Elias-López and Matteo Cantiello and Daniele Viganò and Fabio Del Sordo and Simranpreet Kaur and Clàudia Soriano-Guerrero}, doi = {10.3847/1538-4357/adf057}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {38}, shortjournal = {The Astrophys. J.}, title = {Rossby number regime, convection suppression, and dynamo-generated magnetism in inflated hot jupiters}, volume = {990}, year = {2025}, }
• (2025). Complete survey of r-process conditions: The (Un)robustness of the r-process(es). ApJ, 990(1), 37. (www)

  @article{ , abstract = {Heavy elements are synthesized by the r -process in neutron star mergers and potentially in rare supernovae linked to strong magnetic fields. Expensive hydrodynamic simulations of these extreme environments are usually postprocessed to calculate the nucleosynthesis. In contrast, here we follow a site-independent approach based on three key parameters: electron fraction, entropy, and expansion timescale. Our model reproduces the results based on hydrodynamic simulations. Moreover, the 120,000 astrophysical conditions analyzed allow us to systematically and generally explore the astrophysical conditions of the r -process, also beyond those found in current simulations. Our results show that a wide range of conditions produce very similar abundance patterns explaining the observed robustness of the r -process between the second and third peak. Furthermore, we cannot find a single condition that produces the full solar r -process pattern from first to third peak. Instead, a superposition of at least two or three conditions or components is required to reproduce the typical r -process pattern as observed in the solar system and very old stars. The different final abundances are grouped into eight nucleosynthesis clusters, which can be used to select representative conditions for comparisons to observations and investigations of the nuclear physics input.}, archive = {J_ApJ}, author = {Jan Kuske and Almudena Arcones and Moritz Reichert}, doi = {10.3847/1538-4357/adf0f7}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {37}, shortjournal = {The Astrophys. J.}, title = {Complete survey of r-process conditions: The (Un)robustness of the r-process(es)}, volume = {990}, year = {2025}, }
• (2025). Constraining star formation in m87 using deep hubble space telescope UV data. ApJ, 990(1), 36. (www)

  @article{ , abstract = {We analyzed the deepest Hubble Space Telescope F275W ultraviolet (UV) imaging of M87 to obtain the most robust constraints on its star formation rate (SFR) and star formation history (SFH). After removing the galaxy continuum and globular clusters, we detected an excess of UV point sources near the center. By comparing their colors to young stellar source (YSS) colors generated by stochastically simulated star formation (SF) for various SFRs and SFHs, we ruled out their origin as a UV-upturn population and identified them as YSS. We found an extremely low SFR of ∼2 × 10 −5 M ⊙ yr −1 in M87, with evidence of a weak starburst ∼125 Myr ago that formed ∼1000 M ⊙ of stars. Unlike other cool-core clusters where SF is stronger and directly linked to cooling gas, we found no spatial correlation between YSS and H α filaments. Comparing SF activity with M87’s active galactic nucleus (AGN) outburst history suggests that recent AGN feedback events (≲12 Myr ago) neither triggered nor were associated with any detectable SF; however, earlier outbursts may have triggered weak starbursts. We detected UV filaments cospatial with H α filaments with similar lengths and widths, though they are obscured by dust near the center. These filaments are likely powered by metal-line emission from collisional ionization, suggesting ongoing low-level precipitation of the intracluster medium. Our results indicate that AGN feedback has quenched SF significantly in M87 for at least 200 Myr, even though some precipitation persists. Additionally, we identified a hotspot created by the counterjet, with the spectral index also constrained.}, archive = {J_ApJ}, author = {Prathamesh Tamhane and William Waldron and Ming Sun and Silvia Martocchia and Claudia Maraston and Alessandro Boselli and William Forman and Massimo Gaspari and Juhi Tiwari and Megan Donahue and G. Mark Voit and Tim Edge and Grant Tremblay and Daniel Thomas}, doi = {10.3847/1538-4357/adf20d}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {36}, shortjournal = {The Astrophys. J.}, title = {Constraining star formation in m87 using deep hubble space telescope UV data}, volume = {990}, year = {2025}, }
• (2025). Imprints of different types of low-angular-momentum accretion flow solutions in general relativistic hydrodynamic simulations. ApJ, 990(1), 35. (www)

  @article{ , abstract = {Depending on the astrophysical source and its environment, the accretion flows can exhibit a variety of behaviors and characteristics in accordance with the type of solutions. We study low-angular-momentum accretion flows onto black holes using 2D general relativistic hydrodynamic simulations to find imprints of different types of accretion solutions. Such flows, relevant to X-ray binaries and wind-fed low-luminosity active galactic nuclei, often lack sufficient angular momentum to form standard accretion disks. We initialize simulations with semianalytical transonic solutions defined by specific energy ( {{ \mathcal E }}_{0} ) and angular momentum ( λ 0 ), allowing a systematic classification of flow types with: (i) an outer sonic point, (ii) an inner sonic point, and (iii) both, exhibiting shock transitions. Only solutions with two sonic points produce hot, thermally driven bipolar jets/outflows with Lorentz factors up to γ ∼ 2, despite the absence of magnetic fields. Using a general relativistic radiation transfer calculation, we compute broadband spectra and images at X-ray (1 keV) from bremsstrahlung emission. Radiative properties depend strongly on the type of accretion solution. Solutions with inner sonic points produce the brightest and most extended X-ray emission, while outer-point solutions produce compact, fainter signals. These multidimensional models are thus essential for predicting radiative signatures and will enable the development of semianalytical tools for interpreting X-ray binaries and possibly Sgr A* in weak magnetic field regimes.}, archive = {J_ApJ}, author = {Indu K. Dihingia and Akhil Uniyal and Yosuke Mizuno}, doi = {10.3847/1538-4357/adf221}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {35}, shortjournal = {The Astrophys. J.}, title = {Imprints of different types of low-angular-momentum accretion flow solutions in general relativistic hydrodynamic simulations}, volume = {990}, year = {2025}, }
• (2025). The impact of foregrounds on dark ages measurements with the highly redshifted 21 cm line. ApJ, 990(1), 34. (www)

  @article{ , abstract = {Studies of the cosmic dark ages (30 ≲ z ≲ 150) using the highly redshifted 21 cm line of neutral hydrogen offer unparalleled amounts of cosmological information, and recent years have seen the refinement of concepts for such experiments (e.g., CoDEX and FarView), nominally feasible with technology and resources in the next one to two decades. This work studies how the “foreground wedge”—a term in the 21 cm cosmology literature referring to the contamination of power spectrum modes through the combination of smooth-spectrum foreground emission and the frequency-dependent point-spread function of a radio interferometer—manifests at these very high redshifts. We find the effect is more significant than at epoch of reionization redshifts targeted by current ground-based experiments, with foreground avoidance techniques (which discard all k modes falling within the wedge) typically losing 1 order of magnitude of sensitivity. Given the extreme faintness of the 21 cm signal from the cosmic dark ages and the very high sky temperatures (the dominant source of noise) at low radio frequencies, we conclude that some level of foreground subtraction will be necessary to enable dark ages 21 cm cosmology with experiments of the scale believed to be achievable in the near term.}, archive = {J_ApJ}, author = {Jonathan C. Pober and Willow Smith}, doi = {10.3847/1538-4357/adf6b2}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {34}, shortjournal = {The Astrophys. J.}, title = {The impact of foregrounds on dark ages measurements with the highly redshifted 21 cm line}, volume = {990}, year = {2025}, }
• (2025). On type 1 active galactic nuclei with double-peaked [O iii]. II. properties of long-term optical variability. ApJ, 990(1), 33. (www)

  @article{ , abstract = {Double-peaked [O iii ] profiles could potentially indicate kiloparsec-scale dual active galactic nuclei (AGNs). We analyze long-term optical light curves of 35 type 1 AGNs with such features from our recent catalog in Zheng et al. These light curves are obtained from the Catalina Sky Survey and modeled using a damped random walk process. A control sample of 210 normal type 1 AGNs, matched in redshift, intrinsic luminosity, and black hole mass, is also studied. If the double-peaked [O iii ] is caused by two type 1 AGNs (dual type 1 AGN), then the combined variability from the two AGNs would be expected to differ from that of a single type 1 AGN. However, there is no statistically significant difference in the variability timescale τ and intrinsic variability amplitude σ between these double-peaked AGNs and the control sample of 210 normal type 1 AGNs. Crucially, computer simulations reveal that dual AGN systems systematically produce lower variability amplitudes than single AGNs, which is inconsistent with the observed variability properties of our double-peaked [O iii ] sample. Moreover, simulations suggest that the fraction of dual type 1 AGNs is ∼3%, indicating that double-peaked [O iii ] may not be a reliable indicator of dual type 1 AGNs in these systems. However, this does not rule out the possibility that some objects may still host dual AGNs involving other combinations, such as type 1+type 2 AGNs. Future studies with larger samples and higher-quality light curves will help clarify the true nature of these systems.}, archive = {J_ApJ}, author = {Qi Zheng and Xingyu Zhu and Xueguang Zhang and Qirong Yuan}, doi = {10.3847/1538-4357/adf738}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {33}, shortjournal = {The Astrophys. J.}, title = {On type 1 active galactic nuclei with double-peaked [O iii]. II. properties of long-term optical variability}, volume = {990}, year = {2025}, }
• (2025). Polka-dotted stars: A hierarchical model for mapping stellar surfaces using occultation light curves and the case of TOI-3884. ApJ, 990(1), 32. (www)

  @article{ , abstract = {We present StarryStarryProcess , a novel hierarchical Bayesian framework for mapping stellar surfaces using exoplanet transit light curves. While previous methods relied solely on stellar rotational light curves—which contain limited information about spot properties—our approach leverages planetary transits as probes of stellar surfaces. When a planet crosses a spot during transit, it creates a distinctive change in the light curve that directly reveals spot properties. Our model integrates planetary transit modeling with stellar variability analysis by combining the spherical harmonic surface map representation from starry , the probabilistic approach to spot properties of StarryProcess , and a comprehensive transit model that accounts for spot-crossing events during transits. We demonstrate through synthetic data experiments that our model successfully recovers spot distributions, stellar orientation, and spot physical properties. We extend the framework to handle evolving stellar surfaces through time-dependent modeling. Applying our method to TESS observations of TOI-3884, we find evidence for high-latitude spot concentrations and significant spin–orbit misalignment. The transit-based approach overcomes fundamental limitations of previous models by providing constraints on spot properties that would remain hidden in the null space of rotational light curves alone. This methodology enables more accurate exoplanet characterization by disentangling stellar activity due to starspots from planetary signals while simultaneously providing insights into stellar magnetic activity patterns. The whole paper is reproducible and can be found by clicking the GitHub icon ✎ .}, archive = {J_ApJ}, author = {Sabina Sagynbayeva and Will M. Farr and Brett M. Morris and Rodrigo Luger}, doi = {10.3847/1538-4357/adf6be}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {32}, shortjournal = {The Astrophys. J.}, title = {Polka-dotted stars: A hierarchical model for mapping stellar surfaces using occultation light curves and the case of TOI-3884}, volume = {990}, year = {2025}, }
• (2025). The first photometric evidence of a Transient/Variable source at z > 5 with JWST. ApJ, 990(1), 31. (www)

  @article{ , abstract = {The James Webb Space Telescope (JWST) discovered 79 transients out to z ∼ 4.8 through the JADES Transient Survey (JTS), but the JTS did not find any z > 5 transients. We present the first photometric evidence of a z > 5 transient/variable source with JWST. The source, AT 2023adya, resides in a z spec = 5.274 galaxy in GOODS-N, which dimmed from m F356W = 26.05 ± 0.02 mag to 26.24 ± 0.02 mag in the rest-frame optical over approximately 2 rest-frame months, producing a clear residual signal in the difference image ( m F356W = 28.01 ± 0.17 mag; SN var = 6.09) at the galaxy center. Shorter-wavelength bands (F090W/F115W) show no rest-frame UV brightness change. Based on its rest-frame V -band absolute magnitude ( M V = −18.48 mag), AT 2023adya could be any core-collapse supernova (SN) subtype or an SN Ia. However, due to low SN Ia rates at high redshift, the SN Ia scenario is unlikely. Alternatively, AT 2023adya may be a variable active galactic nucleus (AGN). The NIRCam/Grism spectrum shows no broad H α emission line (FWHM = 130 ± 26 km s −1 ), but we cannot exclude the existence of a faint broad line and therefore cannot exclude the AGN scenario. AT 2023adya is unlikely to be a tidal disruption event (TDE) because the TDE models matching the observed brightness changes have low event rates. Although it is not possible to determine AT 2023adya’s nature based on the two-epoch single-band photometry alone, this discovery pushes the transient/variable science frontier past z = 5 and toward the Epoch of Reionization.}, archive = {J_ApJ}, author = {Christa DeCoursey and Eiichi Egami and Fengwu Sun and Arshia Akhtarkavan and Rachana Bhatawdekar and Andrew J. Bunker and David A. Coulter and Michael Engesser and Ori D. Fox and Sebastian Gomez and Kohei Inayoshi and Benjamin D. Johnson and Mitchell Karmen and Conor Larison and Xiaojing Lin and Jianwei Lyu and Seppo Mattila and Takashi J. Moriya and Justin D. R. Pierel and Dávid Puskás and Armin Rest and George H. Rieke and Brant Robertson and Sepehr Salamat and Louis-Gregory Strolger and Sandro Tacchella and Christian Vassallo and Christina C. Williams and Yossef Zenati and Junyu Zhang}, doi = {10.3847/1538-4357/ade78c}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {31}, shortjournal = {The Astrophys. J.}, title = {The first photometric evidence of a Transient/Variable source at z > 5 with JWST}, volume = {990}, year = {2025}, }
• (2025). Expansion signatures in 35 h II regions traced by SOFIA [C II] emission. ApJ, 990(1), 30. (www)

  @article{ , abstract = {We analyze the expansion signatures of 35 H II regions mapped in [C II ] 158 μ m emission by the Stratospheric Observatory for Infrared Astronomy. The [C II ] emission primarily traces photodissociation regions (PDRs) at the transition between ionized and neutral gas. The brightness and narrow line width of [C II ] allow us to measure PDR expansion. Bubble-shaped regions often exhibit expansion, while irregular-shaped ones are less likely to. Of the 35 H II regions, 12 (∼34%) exhibit clear expansion in position–velocity diagrams, making them expansion candidates (ECs), with an average expansion velocity of ∼12.2 km s −1 . The remaining 23 regions show no clear expansion signatures, though they may still be expanding below detection limits. Blueshifted expansion is more common (eight ECs solely blueshifted, one redshifted, three both), with mean velocities of ∼10.9 km s −1 (blueshifted) and ∼13.2 km s −1 (redshifted). A comparison of our observations to spherical expansion models supports expansion in eight of 12 ECs. Estimated dynamical ages are 10–100 times shorter than the ionizing star lifetimes, in agreement with the results of previous studies. Of the 35 regions, 14 (∼40%) appear as [C II ] bubbles; nine of the 12 ECs are bubble-shaped. Thermal pressure likely drives expansion in M43, while stellar winds dominate in M17, M42, RCW 120, and RCW 79. For other ECs, available data do not allow a definitive conclusion. Larger samples and more information about ionizing sources are needed to refine our understanding of H II region feedback and evolution.}, archive = {J_ApJ}, author = {T. Faerber and L. D. Anderson and M. Luisi and L. Bonne and N. Schneider and V. Ossenkopf-Okada and A. G. G. M. Tielens and R. Simon and M. Röllig}, doi = {10.3847/1538-4357/ade852}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {30}, shortjournal = {The Astrophys. J.}, title = {Expansion signatures in 35 h II regions traced by SOFIA [C II] emission}, volume = {990}, year = {2025}, }
• (2025). Compact ionized gas region surrounded by porous neutral gas in a dusty lyman break galaxy at redshift z = 8.312. ApJ, 990(1), 29. (www)

  @article{ , abstract = {Porous interstellar medium (ISM) structure in galaxies at the epoch of reionization gives us a hint to understand what types of galaxies contribute to reionization. Although recent studies have pointed out the positive correlation between high ionizing photon escape fractions and high [O iii ] 88 μ m/[C ii ] 158 μ m ratios found in UV-luminous star-forming galaxies at z > 6 with the Atacama Large Millimeter/submillimeter Array, previous studies have paid little attention to the neutral gas porosity that allows ionizing photons to escape. Here we present a detailed analysis of a z = 8.312 Lyman break galaxy, MACS0416_Y1 with a high L [O III ] 88 μ m / L [C II ] 158 μ m ratio (≈9) and dust continuum detection. We construct a multiphase ISM model incorporating the neutral gas covering fraction ( c ov PDR ). The best-fit model reveals a cov PDR ≈ 25%, indicating that ≈75% of the ionized gas region is exposed to intercloud space. We confirm that our conclusions hold even when varying star formation history, stellar age, gas/stellar metallicity, and carbon-to-oxygen abundance ratio. This finding meets one of the necessary conditions for galaxies to have a nonzero escape fraction of ionizing photons and supports recent studies that galaxies with a high [O iii ] 88 μ m/[C ii ] 158 μ m ratio, such as MACS0416_Y1, could contribute to cosmic reionization. Furthermore, the modeled H ii region with the best-fitting parameters has a typical size ( D = 0.90 pc) and gas density ( {\mathrm{log}}\,{n}_{{\rm{H}},{\rm{c}}}/{{\rm{cm}}}^{-3}=2.7 ) that are comparable to local compact H ii regions. This suggests that the H ii regions in MACS0416_Y1 are in an early evolutionary stage.}, archive = {J_ApJ}, author = {Masato Hagimoto and Yoichi Tamura and Akio K. Inoue and Hideki Umehata and Tom J. L. C. Bakx and Takuya Hashimoto and Ken Mawatari and Yuma Sugahara and Yoshinobu Fudamoto and Yuichi Harikane and Hiroshi Matsuo and Akio Taniguchi}, doi = {10.3847/1538-4357/ade87e}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {29}, shortjournal = {The Astrophys. J.}, title = {Compact ionized gas region surrounded by porous neutral gas in a dusty lyman break galaxy at redshift z = 8.312}, volume = {990}, year = {2025}, }
• (2025). Microscopic current sheets and fast tearing modes in plasma turbulence. ApJ, 990(1), 28. (www)

  @article{ , abstract = {Since the seminal work by W. H. Matthaeus & S. L. Lamkin, a large amount of evidence has been collected over the years that magnetic reconnection can disrupt current sheets formed in turbulence. The details about how this happens, however, are not clear, yet. The observation of plasmoids suggests that tearing-type modes are involved, but their nature of spontaneous linear instabilities developing on a static (or at most steady) magnetic equilibrium poses strong constraints on their growth rate versus the timescale of the current sheet evolution. None of the tearing-based scenarios, which to date are most credited in literature, seems to fulfill both this constraint and other consistency requirements on the equilibrium profile. In revising them and the main hypotheses, which any tearing-based theory for 2D turbulent reconnection must satisfy, we propose a possible explanation—supported by numerical calculations—for why tearing modes may be relevant. This explanation is grounded on the microscopic thickness that current sheets attain in turbulence, which makes the growth rates of tearing modes large enough for the instability to possibly develop. At the same time, this implies that theoretical growth rates obtained from a boundary layer analysis cannot be applied in this case. We discuss a few implications of these elements in solar wind turbulence and in comparison with alternative models for tearing-based turbulent reconnection that are available in literature.}, archive = {J_ApJ}, author = {Homam Betar and Daniele Del Sarto}, doi = {10.3847/1538-4357/adea47}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {28}, shortjournal = {The Astrophys. J.}, title = {Microscopic current sheets and fast tearing modes in plasma turbulence}, volume = {990}, year = {2025}, }
• (2025). Inactive longitude and superflare in the active single-lined pre-main-sequence binary v2279 cyg. ApJ, 990(1), 27. (www)

  @article{ , abstract = {Young, solar-like stars in the pre-main-sequence (PMS) stage exhibit vigorous magnetic activity that significantly influences their circumstellar environments and the processes of planetary formation and evolution. In binary systems, tidal forces and magnetic interactions can further shape the magnetic geometry. We report a longitudinal preference of starspots, chromospheric activities, and flares in the active single-lined spectroscopic PMS binary system V2279 Cyg, based on long-term photometric observations from Kepler and TESS alongside spectroscopic data from LAMOST. The system is classified as a weak-line T Tauri binary, with component masses estimated at 0.86 M ⊙ and 0.27 M ⊙ . V2279 Cyg’s nearly circular orbit is synchronized with its 4.126 day rotational period. Observations reveal large starspot regions clustered near the far-side hemisphere. Spectroscopic data show strong, double-peak H α emission, the strength of which is highly correlated with starspot distribution, indicating the presence of an active longitude on the primary star. We also mapped the prominence structure corotating with the primary star, suggesting a dense structure close to the near-side hemisphere. Furthermore, we identify an inactive longitude of flares during the 4 yr Kepler observations, where the frequency of flare activity is significantly reduced after the superior conjunction, marking the first such identification in active binary systems. Additionally, a white light superflare, releasing energy of 2.5 × 10 37 erg, was detected in TESS observations. These findings provide valuable insights into the magnetic field geometry and dynamo processes in PMS binaries, underscoring the critical role of tidal interactions in shaping magnetic activities.}, archive = {J_ApJ}, author = {Xueying Hu and Tianqi Cang and Jian-Ning Fu and Xuan Wang and Keyu Xing and Haotian Wang and Pascal Petit and Jiaxin Wang and Yong Yang and He Zhao}, doi = {10.3847/1538-4357/adeb69}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {27}, shortjournal = {The Astrophys. J.}, title = {Inactive longitude and superflare in the active single-lined pre-main-sequence binary v2279 cyg}, volume = {990}, year = {2025}, }
• (2025). The influence of interplanetary magnetic field orientations on the martian bow shock and magnetosheath magnetic field. ApJ, 990(1), 26. (www)

  @article{ , abstract = {Unlike Earth, Mars lacks a global intrinsic magnetic field but has regional crustal magnetic fields concentrated in its southern hemisphere. This unique configuration leads to distinctive interactions with the solar wind. In this study, we have investigated the influence of the interplanetary magnetic field (IMF) orientation on the Martian bow shock (BS) and the magnetosheath magnetic field, using data from the Mars Atmosphere and Volatile Evolution mission from the years 2014 to 2020. Our results have demonstrated that the IMF orientation can significantly affect the location of the Martian BS and the magnitude of the magnetosheath magnetic field. Compared to nonradial IMF conditions, radial IMF conditions bring the Martian BS closer to the planetary surface. Additionally, under radial IMF conditions, the proportional increase in the magnetic field magnitude from the solar wind to the dayside magnetosheath is smaller, due to the absence of magnetic pileup processes. However, under both nonradial and radial IMF conditions, the proportional increases in the magnetic field magnitude from the solar wind to the terminator and nightside magnetosheath are similar. Moreover, both the Martian BS and the magnetosheath magnetic field magnitude exhibit dawn–dusk and north–south asymmetries. These asymmetries are determined by both the orientation of the IMF and the presence of regional crustal magnetic fields. Our results suggest that the IMF orientation plays a crucial role in the interaction between the solar wind and Mars.}, archive = {J_ApJ}, author = {Yangjun Chen and Mingyu Wu and Xuesong Leng and Sudong Xiao and Guoqiang Wang and Heyin Wang and Peng E and Aimin Du and Tielong Zhang}, doi = {10.3847/1538-4357/adeb87}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {26}, shortjournal = {The Astrophys. J.}, title = {The influence of interplanetary magnetic field orientations on the martian bow shock and magnetosheath magnetic field}, volume = {990}, year = {2025}, }
• (2025). Magnetic white dwarfs in the SDSS 100 pc sample: Further evidence of two formation channels. ApJ, 990(1), 25. (www)

  @article{ , abstract = {We conduct a model atmosphere analysis on all magnetic white dwarfs (MWDs) in the Sloan Digital Sky Survey (SDSS) 100 pc sample. We have 163 magnetic targets in this sample, 87 of which are new discoveries, making this the largest volume-limited survey of MWDs to date. We discuss the distribution of multiple parameters, including mass, cooling age, and field strength. We find strong evidence of two populations of MWDs that form through separate mechanisms based on a cluster analysis of these parameters. The young, high-mass objects typically have high field strengths which indicate a merger origin, while old, average-mass objects have weaker fields that likely originated through a crystallization-induced dynamo or previous evolution stages. When comparing young and old objects, two-sample Kolmogorov–Smirnov tests yield statistically significant differences between the field strengths and masses of the magnetic targets. We use a Gaussian mixture model to identify where these populations lie in parameter space, and we find two groups centered at distinct cooling ages, masses, and field strengths of 2.9 Gyr, 0.71 M ⊙ , 3.7 MG and 1.8 Gyr, 0.96 M ⊙ , 84 MG, respectively. Our results further support the dual formation channel previously reported in the literature. The occurrence of magnetism strongly correlates with the onset of crystallization. However, given the breakout times required for a crystallization dynamo, we find that many of our older, average-mass objects can be better explained with a core-convective dynamo that forms on the main sequence.}, archive = {J_ApJ}, author = {Adam Moss and Mukremin Kilic and Pierre Bergeron and Warren R. Brown and Gracyn Jewett and Marcel A. Agüeros and Maria Camisassa and Anthony Burrow}, doi = {10.3847/1538-4357/aded8f}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {25}, shortjournal = {The Astrophys. J.}, title = {Magnetic white dwarfs in the SDSS 100 pc sample: Further evidence of two formation channels}, volume = {990}, year = {2025}, }
• (2025). Analysis of WISPR images of the near-sun heliospheric current sheet region from parker solar probe encounters 4 and 5 and comparison with the in situ observations. ApJ, 990(1), 24. (www)

  @article{ , abstract = {We present an analysis of Wide-field Imager for Solar PRobe (WISPR) images of the near-Sun heliospheric current sheet (HCS) region from the Parker Solar Probe (PSP) in 2020 January and June. Previous analysis of the solar wind data from PSP’s in situ instruments for these periods has shown multiple signatures of magnetic reconnection during HCS encounters. The signatures, including field line disconnections, density enhancements, and reconnection flows, indicated that reconnection was nearly always active in the HCS near the Sun. Here, we present an analysis of WISPR white-light observations of the HCS region during the same time periods, using an image-processing technique that enhances changes in the images from frame to frame. This processing reveals the presence of a nearly continual stream of transient density enhancements (“blobs”) within the helmet streamer flow not evident in the standard calibrated-brightness images. The blobs, observed frequently in the helmet streamer flows by white-light imagers, are broadly interpreted as resulting from reconnection in the vicinity of the HCS. Thus, the WISPR observations are consistent with the in situ data finding that reconnection is almost always active in the HCS near the Sun. We use the Tracking and Fitting technique to determine the trajectory and size of a few of the more distinct blobs. We confirm that the blobs lie near the HCS and find that the sizes of the imaged blobs are similar to the size estimates for possible blobs seen in situ in the HCS at similar distances from the Sun.}, archive = {J_ApJ}, author = {Paulett C. Liewer and Samuel T. Badman and Mark Linton and T. D. Phan and Guillermo Stenborg and Angelos Vourlidas}, doi = {10.3847/1538-4357/adee13}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {24}, shortjournal = {The Astrophys. J.}, title = {Analysis of WISPR images of the near-sun heliospheric current sheet region from parker solar probe encounters 4 and 5 and comparison with the in situ observations}, volume = {990}, year = {2025}, }
• (2025). Cross calibration of galaxy cluster temperatures measured with NuSTAR, XMM-newton, and chandra. ApJ, 990(1), 23. (www)

  @article{ , abstract = {The use of galaxy clusters to constrain cosmology is limited in part due to uncertainties in derived cluster masses, which often depend on the gas temperature. Unfortunately, there exists a longstanding discrepancy in temperature measurements of the same galaxy clusters made by the two most sensitive X-ray observatories, Chandra and XMM-Newton. The NuSTAR X-ray Observatory’s greater sensitivity to the exponential turnover in the bremsstrahlung continuum allows for more precise and potentially more accurate galaxy cluster temperature estimates, especially given its unique ability to independently calibrate its optics in orbit. We present new NuSTAR spectra of 10 relaxed (5 keV < kT < 10 keV) clusters, extracted from identical regions as previous spectra from Chandra and XMM-Newton. The 3–20 keV spectra are well fit by single temperature models, and fits done in narrower bandpasses provide no clear evidence in support of the existence of multi-temperature gas. We find NuSTAR temperatures are typically ∼15% higher than XMM-Newton temperatures. In contrast, good agreement is found between NuSTAR and Chandra temperatures for clusters with kT ≲ 7 keV, with Chandra measurements exceeding NuSTAR’s in hotter systems. When more clusters are included, the trend is reinforced and can be extended to higher temperatures. A generic increase to Chandra’s E > 2 keV effective area (∼5% at 5 keV) is found to explain the trend reasonably well. These results demonstrate the potential for NuSTAR data to address the two-decade-old temperature discrepancy between Chandra and XMM-Newton.}, archive = {J_ApJ}, author = {Fiona Lopez and Daniel R. Wik and Cicely Potter and Randall A. Rojas Bolivar and Ayşegül Tümer and Dominique Eckert and Fabio Gastaldello and Brian W Grefenstette and Kristin Madsen and Ben Maughan and Eric D. Miller and Gerrit Schellenberger and A. N. Wallbank}, doi = {10.3847/1538-4357/adee8f}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {23}, shortjournal = {The Astrophys. J.}, title = {Cross calibration of galaxy cluster temperatures measured with NuSTAR, XMM-newton, and chandra}, volume = {990}, year = {2025}, }
• (2025). Insights from the “Red devil” AT 2022fpx: A dust-reddened family of tidal disruption events excluded by their apparent red color?. ApJ, 990(1), 22. (www)

  @article{ , abstract = {We report unnoticed but intriguing features in the peculiar nuclear transient AT 2022fpx, and investigate its type. These features include the constantly red optical color of g − r > 0, a stable soft X-ray flare ( kT ∼ 100 eV) in the past ∼550 days, a prominent mid-infrared echo peaked at ∼10 43.3 erg s −1 , and the confirmation of a weak active galactic nucleus by weak flares in pre-event Wide-field Infrared Survey Explorer mid-infrared light curves with no contemporary optical, radio or X-ray counterparts. The combination of the optical red color and possible origin of a tidal disruption event (TDE) in AT 2022fpx is particularly attractive, as it challenges the most widely accepted and adopted “blue color” criterion for optical TDE selection. Although we still cannot confirm whether the red color is intrinsic, we do find that the “blue color” criterion can filter out normal TDEs whose optical–UV spectral energy distributions (SEDs) are either severely contaminated by prominent emission lines (especially H α ) or heavily dust-reddened. Hence, its potential selection effect may have been imprinted on the whole optical TDE family. Blackbody fitting on the optical (rest-frame ∼4000–7000 Å) and optical–UV (∼2000–7000 Å) SEDs of four TDEs with high-cadence UV observations shows that T bb rises by ∼40%−110% when the UV bands are included. The power-law models ( f λ ∝ λ − α with α = 2–3) can fit the rest-frame ∼2000–7000 Å SEDs more consistently, indicating that SEDs should peak at shorter wavelengths, than simple blackbodies. Hence, the estimated released energy for the optical–UV-bright but X-ray-faint TDEs based on blackbody SED fitting should be significantly lower than the intrinsic energy.}, archive = {J_ApJ}, author = {Zheyu Lin and Ning Jiang and Yibo Wang and Xu Kong and Shifeng Huang and Zesen Lin and Chen Qin and Tianyu Xia}, doi = {10.3847/1538-4357/adef10}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {22}, shortjournal = {The Astrophys. J.}, title = {Insights from the “Red devil” AT 2022fpx: A dust-reddened family of tidal disruption events excluded by their apparent red color?}, volume = {990}, year = {2025}, }
• (2025). A prediction of solar cycle maxima using visibility graphs. ApJ, 990(1), 21. (www)

  @article{ , abstract = {We apply a complex network approach to analyze the time series of five solar parameters, and propose a strategy to predict the number of sunspots for the next solar maximum, and when this maximum will occur. The approach is based on the visibility graph (VG) algorithm, and a slightly modified version of it, the horizontal VG, which maps a time series into a complex network. Various network metrics exhibit either an exponential or a scale-free behavior, and we find that the evolution of the characteristic decay exponents is consistent with variations of the sunspot number along solar cycles. During solar minimum, the sunspot number and the F10.7 cm radio flux time series have characteristic decay exponents that correlate well with the next maximum sunspot number, suggesting that they may be good precursors of the intensity of the next solar maximum.}, archive = {J_ApJ}, author = {Eduardo Flández and Víctor Muñoz}, doi = {10.3847/1538-4357/adef43}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {21}, shortjournal = {The Astrophys. J.}, title = {A prediction of solar cycle maxima using visibility graphs}, volume = {990}, year = {2025}, }
• (2025). Ab initio entropy calculations of water predict the interiors of uranus and neptune to be 15%–30% colder than previous models. ApJ, 990(1), 20. (www)

  @article{ , abstract = {Ab initio free energy calculations are employed to derive the entropy of liquid and superionic water over a wide range of conditions in the interiors of Uranus and Neptune. The resulting adiabats are much shallower in pressure–temperature space than those adopted for earlier models of Uranus and Neptune. Our models for their interiors are thus much colder, increasing the likelihood that diamond rain or the recently predicted phase separation of planetary ices has occurred in the mantles of ice giant planets. Based on our ab initio data, we construct interior models for Uranus and Neptune with the concentric MacLaurin spheroid method that match the existing gravity measurements. We compare fully convective models with models that include a convective boundary between liquid and superionic water. We also share a code to characterize giant planet atmospheres where para- and ortho-hydrogen as well as helium are present.}, archive = {J_ApJ}, author = {Burkhard Militzer}, doi = {10.3847/1538-4357/adef48}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {20}, shortjournal = {The Astrophys. J.}, title = {Ab initio entropy calculations of water predict the interiors of uranus and neptune to be 15%–30% colder than previous models}, volume = {990}, year = {2025}, }
• (2025). Production of radioactive 22Na in core-collapse supernovae: The ne-E(L) component in presolar grains and its possible consequences on supernova observations. ApJ, 990(1), 19. (www)

  @article{ , abstract = {Presolar graphite grains carry the isotopic signatures of their parent stars. A significant fraction of presolar graphites show isotopic abundance anomalies relative to solar for elements such as O, Si, Mg, and Ca, which are compatible with nucleosynthesis in core-collapse supernovae (CCSNe). Therefore, they must have condensed from CCSN ejecta before the formation of the Sun. Their most puzzling abundance signature is the 22 Ne-enriched component Ne-E(L), interpreted as the effect of the radioactive decay of 22 Na ( T 1/2 = 2.6 yr). Previous works have shown that if H is ingested into the He shell and not fully destroyed before the explosion, the CCSN shock in the He-shell material produces large amounts of 22 Na. Here we focus on such CCSN models, showing a radioactive 26 Al production compatible with grain measurements, and analyze the conditions of 22 Na nucleosynthesis. In these models, 22 Na is mostly made in the He shell, with a total ejected mass varying between 2.6 × 10 −3 M ⊙ and 1.9 × 10 −6 M ⊙ . We show that such 22 Na may already impact the CCSN light curve 500 days after the explosion, and at later stages it can be the main source powering the CCSN light curve for up to a few years before 44 Ti decay becomes dominant. Based on the CCSN yields above, the 1274.53 keV γ -ray flux due to 22 Na decay could be observable for years after the first CCSN light is detected, depending on the distance. This makes CCSNe possible sites to detect a 22 Na γ -ray signature consistently with the Ne-E(L) component found in presolar graphites. Finally, we discuss the potential contribution from 22 Na decay to the Galactic positron annihilation rate.}, archive = {J_ApJ}, author = {Marco Pignatari and Sachiko Amari and Peter Hoppe and C. Fryer and S. Jones and A. Psaltis and A. M. Laird and F. Herwig and L. Roberti and Thomas Siegert and Maria Lugaro}, doi = {10.3847/1538-4357/adef4c}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {19}, shortjournal = {The Astrophys. J.}, title = {Production of radioactive 22Na in core-collapse supernovae: The ne-E(L) component in presolar grains and its possible consequences on supernova observations}, volume = {990}, year = {2025}, }
• (2025). Investigating the correlation between ZTF tidal disruption events and IceCube high-energy neutrinos. ApJ, 990(1), 18. (www)

  @article{ , abstract = {Investigating the correlation between the tidal disruption event (TDE) population and IceCube neutrinos could help us better understand whether TDEs could be potential high-energy neutrino emitters. In this paper, we perform a systematic search for TDEs that are associated with neutrinos in a sample including 143 IceCube neutrino alert events and 52 TDEs classified by the Zwicky Transient Facility Bright Transient Survey. Furthermore, considering that the TDEs/TDE candidates reported as potential IceCube neutrino emitters are all accompanied by infrared (IR) echo emission, we further select TDEs with IR echoes from these 52 TDEs as a subsample to examine their correlation with neutrinos. Based on the Wide-field Infrared Survey Explorer mission database, seven TDEs are identified as having IR echoes. Then we employ Monte Carlo simulations to quantify the correlation between the TDE sample/subsample and IceCube neutrinos. Finally, after considering spatial and temporal criteria, the seven TDEs with IR echoes show the most significant correlation at the 2.46 σ confidence level. If we tentatively further take the time delay factor into account, the correlation enhances to the 2.66 σ confidence level. The correlation is primarily contributed by two TDEs: AT2019dsg and AT2019azh. The latter’s association with a neutrino alert, IC230217A, is newly reported in this work. We discuss the possible physical connection between AT2019azh and the neutrino event IC230217A.}, archive = {J_ApJ}, author = {Ming-Xuan Lu and Yun-Feng Liang and Xiang-Gao Wang and Xue-Rui Ouyang}, doi = {10.3847/1538-4357/adef54}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {18}, shortjournal = {The Astrophys. J.}, title = {Investigating the correlation between ZTF tidal disruption events and IceCube high-energy neutrinos}, volume = {990}, year = {2025}, }
• (2025). Anisotropy of core-collapse supernovae effected by the disks of active galactic nuclei. ApJ, 990(1), 17. (www)

  @article{ , abstract = {Active galactic nuclei (AGN) disks provide dense environments that influence star formation, evolution, and migration. In AGN disks, pressure gradients and migration accelerations could create the anisotropy of the core-collapse supernovae that occurs when massive stars explode at the end of their lives. In this study, we construct equilibrium equations by considering these two factors and then compute the light curves for three types of progenitor stars at different locations of AGN disks for different supermassive black hole (SMBH) masses, accretion efficiencies, explosion energies, and masses of ejecta. The results show that the migration acceleration has more significant effects on the anisotropic explosions than the pressure gradients of the AGN disks. The anisotropic luminosities are pronounced at large radii, and massive SMBHs would suppress the anisotropy and reduce the total luminosity.}, archive = {J_ApJ}, author = {Jiao-Zhen She and Tong Liu and Bao-Quan Huang and Yun-Feng Wei and Fu-Lin Li and Jin-Jun Geng and Xue-Feng Wu}, doi = {10.3847/1538-4357/adefe6}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {17}, shortjournal = {The Astrophys. J.}, title = {Anisotropy of core-collapse supernovae effected by the disks of active galactic nuclei}, volume = {990}, year = {2025}, }
• (2025). The complex multiwavelength morphology of the peculiar compact galaxy group IC 2431. ApJ, 990(1), 16. (www)

  @article{ , abstract = {We present new Chandra X-ray imaging spectroscopy of the compact galaxy group IC 2431, and compare with archival ultraviolet, optical, infrared, and radio images. IC 2431 is a starburst system containing three tidally distorted disk galaxies. All three galaxies may have active nuclei. One galaxy is classified as an active galactic nucleus (AGN) based on its optical spectrum, a second is identified as a possible X-ray AGN based on the Chandra data, and the third galaxy may host a radio AGN. In optical images, a prominent dust lane crosses the southern galaxy, while Spitzer infrared images show a dusty bridge connecting the two brightest galaxies. Chandra maps reveal a massive (2 × 10 7 M ⊙ ) concentration of hot gas between these two galaxies, as well as several other knots of hot gas and nonthermal emission. The unabsorbed X-ray luminosity of the hot gas in IC 2431 is ∼1 × 10 42 erg s −1 , which is enhanced by about a factor of 4 relative to the star formation rate, compared to other star-forming galaxies. In radio maps, a bright jet/ridge of radio continuum emission extends 4 kpc from one nucleus. We compare the properties of IC 2431 with those of other interacting galaxy systems, and discuss two different scenarios that may account for the peculiarities of IC 2431: ram pressure stripping of the interstellar medium during a head-on collision between two galaxies, or an AGN-powered radio jet that has been distorted by an interaction with interstellar gas during a tidal encounter between galaxies.}, archive = {J_ApJ}, author = {Beverly J. Smith and Roberto Soria and Douglas A. Swartz and Mark L. Giroux and Curtis Struck and Ryan Urquhart}, doi = {10.3847/1538-4357/adf061}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {16}, shortjournal = {The Astrophys. J.}, title = {The complex multiwavelength morphology of the peculiar compact galaxy group IC 2431}, volume = {990}, year = {2025}, }
• (2025). Timing and spectral studies of SRGA j144459.2−604207 with NICER, einstein probe, IXPE, NuSTAR, insight-HXMT, and INTEGRAL during its 2024 outburst. ApJ, 990(1), 15. (www)

  @article{ , abstract = {SRGA J144459.2−604207 is a newly confirmed accreting millisecond X-ray pulsar and type I X-ray burster. We present the broadband X-ray timing and spectral behaviors of SRGA J144459.2−604207 during its 2024 outburst. The data were collected from NICER, Einstein Probe, Imaging X-ray Polarimetry Explorer (IXPE), Insight Hard X-ray Modulation Telescope (Insight-HXMT), NuSTAR, and INTEGRAL observations. X-ray pulsations have been detected for the 1.5–90 keV energy range throughout the “ON” phase of the outburst from MJD ∼ 60355–60385. We refined the orbital and spin ephemerides assuming a circular orbit, and found that the pulsar was in a spin-up state during MJD ∼ 60361–60377 showing a significant spin-up rate \dot{\nu } of (3.15 ± 0.36) × 10 −13 Hz s −1 . Around MJD ∼ 60377 a swing was detected in the spin evolution accompanied by significantly enhanced pulsed emission. We studied the pulse-profile morphology during the X-ray bursts as observed by Insight-HXMT, IXPE, and NuSTAR. During the bursts, pulsations were detected across the 2–60 keV with shapes broadly consistent with those observed for the persistent emission. We found, however, that the “burst” pulse profiles exhibit significant phase offsets relative to the pre- and postburst profiles. These offsets systematically decrease with increasing energy, Δ ϕ ≈ 0.15, 0.11, and 0.02 for IXPE, Insight-HXMT ME, and HE in 2–8, 5–30, and 20–60 keV, respectively, and Δ ϕ ≈ 0.21, 0.10, and 0.07 for NuSTAR in 3–10, 20–35, and 35–60 keV, respectively, compared to the pre- and postburst profiles. We performed a joint spectral analysis of quasi-simultaneous NICER, NuSTAR, and Insight-HXMT data for two epochs. The resulting spectra from both observations were consistent and well described by an absorbed thermal Comptonization model, nthcomp , plus relativistic reflection, relxillCp .}, archive = {J_ApJ}, author = {Zhaosheng Li and Lucien Kuiper and Yuanyue Pan and Renxin Xu and Yong Chen and Mingyu Ge and Yue Huang and Shumei Jia and Xiaobo Li and Liming Song and Jinlu Qu and Shu Zhang and Lian Tao and Hua Feng and Shuang-Nan Zhang and Maurizio Falanga}, doi = {10.3847/1538-4357/adf0ff}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {15}, shortjournal = {The Astrophys. J.}, title = {Timing and spectral studies of SRGA j144459.2−604207 with NICER, einstein probe, IXPE, NuSTAR, insight-HXMT, and INTEGRAL during its 2024 outburst}, volume = {990}, year = {2025}, }
• (2025). On the correlation between alfvén waves and auroral radio emissions in the jovian system. ApJ, 990(1), 14. (www)

  @article{ , abstract = {Jupiter’s powerful aurorae reflect intense energy dissipation in the magnetosphere–ionosphere system. Recent studies reveal that solar wind compression systematically enhances auroral emission, while the mechanism is not yet fully understood. Alfvén waves were proposed to be responsible for the auroral enhancement, based on the correlation between Alfvénic wave power and ultraviolet auroral intensity revealed by the unprecedented, though limited, observations of Juno and the Hubble Space Telescope. Since auroral energy dissipation produces emissions across multiple frequency bands, we leverage a comprehensive data set of radio emissions from Juno to investigate the relation between Alfvén waves and auroral radiation power. A clear correlation between Alfvén waves and radio emissions was revealed, providing additional supporting evidence for the hypothesis that Alfvén waves contribute to auroral energy dissipation, and the correlation peaked in the region between 40 and 60 R J , providing key insights to the Alfvénic energy source region in the magnetosphere.}, archive = {J_ApJ}, author = {Yuening Chen and Zhonghua Yao and Shengyi Ye}, doi = {10.3847/1538-4357/adf335}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {14}, shortjournal = {The Astrophys. J.}, title = {On the correlation between alfvén waves and auroral radio emissions in the jovian system}, volume = {990}, year = {2025}, }
• (2025). 63Fe–63Mn: A possible strong urca pair and its potential astrophysical impact. ApJ, 990(1), 13. (www)

  @article{ , abstract = {The cooling strength of the Urca pair, 63 Fe– 63 Mn, exhibits an extensive range of variation due to the uncertainty in the spin parity of the ground state of 63 Fe. To investigate the cooling effect of this Urca pair on the thermal evolution of neutron star crusts, we performed simulations on neutron star structure and evolution under various spin-parity assignment scenarios. When adopting recently evaluated nuclear data, 63 Fe– 63 Mn emerges as one of the strongest Urca pairs. In the case of MAXI J0556-332, 63 Fe– 63 Mn is the only pair above the shallow heating layer, significantly impacting the cooling curve and the superburst ignition. Moreover, the constraint on the past nucleosynthesis reduced to one-quarter of its original value, falling within three decades, which enables the validation of nuclear reaction theories in the outer layers of neutron stars. Our results highlight the need for more precise measurements of the β − decay of 63 Mn to better determine the Urca cooling effect of the 63 Fe– 63 Mn pair in accreted neutron star crusts.}, archive = {J_ApJ}, author = {Hao Huang and Kuoang Li and Zhong Liu and Xiaodong Tang and Peng Shuai and Zach Meisel}, doi = {10.3847/1538-4357/adf43f}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {13}, shortjournal = {The Astrophys. J.}, title = {63Fe–63Mn: A possible strong urca pair and its potential astrophysical impact}, volume = {990}, year = {2025}, }
• (2025). Low-angular-momentum black hole accretion: First general relativistic magnetohydrodynamic evidence of standing shocks. ApJ, 990(1), 12. (www)

  @article{ , abstract = {Understanding the dynamics of low-angular-momentum accretion flow around black holes (BHs) is essential for probing extreme plasma behavior in strong gravity, where shock formation can naturally produce variability signatures. In this paper, we perform general relativistic magnetohydrodynamic (GRMHD) simulations of low angular momentum accretion flows onto a BH with different BH spins to investigate the accretion dynamics near the central BH region. The simulation results show the standard and normal evolution regime in all cases. In particular, we report the formation and persistence of standing shocks in low-angular-momentum accretion flows using multidimensional (2D and 3D) GRMHD simulations for the first time. Previous studies did not detect such stable standing shock structures, making our findings a significant advancement in this field. The finding of shock dynamics can be further associated with some radiation features, such as flares observed in Sgr A * and quasiperiodic oscillation signals detected in some X-ray binaries and active galactic nuclei.}, archive = {J_ApJ}, author = {Jirong Mao and Indu K. Dihingia and Yosuke Mizuno and Shigehiro Nagataki}, doi = {10.3847/1538-4357/adf635}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {12}, shortjournal = {The Astrophys. J.}, title = {Low-angular-momentum black hole accretion: First general relativistic magnetohydrodynamic evidence of standing shocks}, volume = {990}, year = {2025}, }
• (2025). Unraveling the role of neutrino processes on the astrophysical production of 94Mo. ApJ, 990(1), 11. (www)

  @article{ , abstract = {The enigmatic origin of the proton-rich nuclei 92 Mo and 94 Mo in the solar system remains one of the most intriguing mysteries in astrophysics, with the definitive production site yet to be identified. Although mechanisms such as the proton-capture reactions, photonuclear reactions, and neutrino processes have been proposed, the underproduction of 94 Mo persists as a puzzle. In this study, we investigate the production of 94 Mo through neutrino-induced processes during core-collapse supernova explosions. By calculating the cross sections of the charged-current reactions 94 Zr ( ν e , e − ) 94 Nb and 95 Mo ( ν e , e − p) 94 Mo, as well as the neutral-current reactions 95 Mo \,(\nu ,{\nu }^{{\prime} } n) 94 Mo, based on supernova explosion models, we explore the contribution of neutrino-nucleus reactions to the abundance of 94 Mo. Our results indicate that these neutrino-induced reactions can account for up to 6.8% of the solar system abundance of 94 Mo. Additionally, we propose that specific temperatures and proton number densities formed by neutrino shock waves could reproduce the solar system abundance ratio of 94 Mo to 92 Mo. This work provides a new perspective on understanding the origin of p -process nuclei in the solar system and establishes a significant theoretical foundation for future research endeavors.}, archive = {J_ApJ}, author = {N. Song and Z. H. Li and G. X. Li and Z. C. Gao and Y. F. Niu}, doi = {10.3847/1538-4357/adf746}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {11}, shortjournal = {The Astrophys. J.}, title = {Unraveling the role of neutrino processes on the astrophysical production of 94Mo}, volume = {990}, year = {2025}, }
• (2025). Interband lag variability in active galactic nuclei across zwicky transient facility data from multiple years. ApJ, 990(1), 10. (www)

  @article{ , abstract = {Interband lags in the optical continua of active galactic nuclei (AGNs) have been observed over years of monitoring, yet their physical origins remain unclear. While variable interband lags have potentially been found in a few individual AGNs, the temporal behavior of the interband lags of an AGN sample has not been explored systematically. Here, we analyze the interband lags of 94 bright AGNs at z < 0.8, using both seasonal 1 yr and full 6 yr gri -band light curves from Zwicky Transient Facility Data Release 22. We find that more than half of the 94 AGNs show significant seasonal variations in the interband lags. Besides, the short-term lags, derived by averaging the lags inferred from multiple seasonal light curves, are consistently smaller than the long-term lags, which are inferred from the full 6 yr light curves. This supports recent theoretical simulations where the lag measurement is sensitive to the baseline of the light curve and the lag variation could be simply attributed to the inherent randomness of AGN variability. Our findings suggest that the interband lags of AGNs are more complex and stochastic than commonly thought, and highlight the importance of high-precision time-domain surveys for uncovering the properties of AGN variability as well as the associated accretion physics.}, archive = {J_ApJ}, author = {Zhen-Bo Su and Zhen-Yi Cai and Hengxiao Guo and Mouyuan Sun and Jun-Xian Wang}, doi = {10.3847/1538-4357/adef13}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {10}, shortjournal = {The Astrophys. J.}, title = {Interband lag variability in active galactic nuclei across zwicky transient facility data from multiple years}, volume = {990}, year = {2025}, }
• (2025). Discovery of diffuse γ-ray emission in the vicinity of g213.0-0.6: Supernova remnant versus the massive star-forming region. ApJ, 990(1), 9. (www)

  @article{ , abstract = {We report the discovery of high-energy γ -ray emission in the vicinity of G213.0-0.6, which is debated as a supernova remnant (SNR) or an ionized hydrogen (H II ) region. Using 16 yr Pass 8 data from Fermi Large Area Telescope, we found three extended sources with different photon spectra in this region, which we label as SrcA, SrcB, and SrcC. Among them, the γ -ray source SrcA with a log-parabola spectrum is spatially coincident with a star-forming region and several OB stars. The power-law spectra source SrcB is spatially coincident with an SNR radio shell. SrcC, with a harder power-law photon spectrum, is located outside of the radio shell structure. All of them are spatially coincident with a dense molecular cloud (MC) in the velocity range of 35–54 km s −1 . In this scenario, SrcB can be interpreted as the GeV counterpart of the SNR, and its γ -ray emission originates from the shock–cloud interaction. SrcA and SrcC originate from the escaped CRs illuminating a nearby MC. For SrcA, another possibility is that the γ -ray emission originates from a young stellar cluster associated with a star-forming region; however, the supporting evidence remains insufficient to draw a definitive conclusion.}, archive = {J_ApJ}, author = {Yuan Li and Gwenael Giacinti and Siming Liu}, doi = {10.3847/1538-4357/adf209}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {9}, shortjournal = {The Astrophys. J.}, title = {Discovery of diffuse γ-ray emission in the vicinity of g213.0-0.6: Supernova remnant versus the massive star-forming region}, volume = {990}, year = {2025}, }
• (2025). Magnetic effect on the evolution of an eccentric and inclined orbit. ApJ, 990(1), 8. (www)

  @article{ , abstract = {We provide a method to calculate the evolution of an eccentric and inclined orbit under the magnetic effect. Taking the unipolar interaction as an example, we study both coplanar and inclined orbits. We calculate the Lorentz force and then the changes in orbital energy and angular momentum. Combined with the total energy dissipation we write down the evolution equations of semimajor axis, eccentricity, inclination, and spin. This set of equations can be used to study the orbital and spin evolution under the magnetic interaction.}, archive = {J_ApJ}, author = {Xing Wei}, doi = {10.3847/1538-4357/adf4c8}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {8}, shortjournal = {The Astrophys. J.}, title = {Magnetic effect on the evolution of an eccentric and inclined orbit}, volume = {990}, year = {2025}, }
• (2025). How early could the milky way’s disk form?. ApJ, 990(1), 7. (www)

  @article{ , abstract = {We investigate early, z > 3, galaxy formation in a cosmological zoom-in simulation of a close, early-forming Milky Way (MW) analog extracted from TNG50 simulation and resimulated with detailed modeling of cold interstellar medium (ISM) formation, coupled with on-the-fly UV radiative transfer, turbulence-regulated star formation, and stellar feedback. In our enhanced-physics simulation, the galaxy develops a bistable ISM structure (warm, with T ∼ 10 4 K, and cold, with T < 100 K) and exhibits significantly more efficient, early, and bursty star formation than in TNG. Notably, the stellar disk of this MW progenitor forms extremely early, around z ∼ 6–7, and exhibits chemo-kinematic properties consistent with the low-metallicity population of the MW stars. The disk forms rapidly, on a timescale of ∼0.2 Gyr, which is significantly shorter than the timescale implied by the observable chemo-kinematic signatures of disk spin-up, ∼0.7 Gyr, due to the scatter in the age–metallicity relation. The rotational support of the gas disk and the location of the galaxy on the main sequence are consistent with early disk galaxies observed by the James Webb Space Telescope and the Atacama Large Millimeter/submillimeter Array at z ∼ 4–7, suggesting that some of these galaxies could be progenitors of MW-like systems. Remarkably, the variation of the global star formation rate (SFR) before disk formation is similar to the observed SFR scatter at these early times. Our findings underscore the critical role of modeling a turbulent cold ISM and turbulence-regulated star formation and feedback in driving early SFR variability, while at the same time enabling early disk formation, without destroying it with overly efficient stellar feedback.}, archive = {J_ApJ}, author = {Vadim A. Semenov and Charlie Conroy and Aaron Smith and Ewald Puchwein and Lars Hernquist}, doi = {10.3847/1538-4357/addf48}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {7}, shortjournal = {The Astrophys. J.}, title = {How early could the milky way’s disk form?}, volume = {990}, year = {2025}, }
• (2025). Active galactic nucleus feedback-induced stellar density expansion in the inner regions of early-type galaxies. ApJ, 990(1), 6. (www)

  @article{ , abstract = {Observations indicate that early-type galaxies exhibit varying slopes in the relation between their central stellar surface density and stellar mass (Σ 1 – M ⋆ ). Low-mass galaxies tend to follow a steep slope, close to 1, while the slope flattens for high-mass early-type galaxies. In our study, we investigate the Σ 1 – M ⋆ scaling relation and its evolution using the Numerical Investigation of Hundred Astrophysical Objects (NIHAO) suite of cosmological simulations and compare our findings with recent results from the MaNGA survey. Our analysis shows that NIHAO galaxies successfully reproduce the observed scaling relation based on the MaNGA survey. Our analysis suggests that active galactic nucleus (AGN) feedback plays a critical role in flattening the Σ 1 slope, by expelling gas from galactic centers, leading to a decrease in both stellar and dark matter density as the gravitational potential becomes shallower. To further support our findings, we conduct high-resolution N -body simulations, which confirm that (sudden) gas removal does substantially alter the stellar density in the central region, consistent with the results from NIHAO. Furthermore, our numerical experiments show that even if the same amount of gas is reaccreted on a typical (longer) freefall time, it is not able to restore the original stellar density. Our study concludes that AGN-feedback-assisted gas removal presents a plausible explanation for the decline in central stellar surface density as observed in massive elliptical galaxies.}, archive = {J_ApJ}, author = {Fazeel Mahmood Khan and Ángel Rodríguez and Andrea V. Macció and Smarika Sharma and Changhyun Cho}, doi = {10.3847/1538-4357/ade99e}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {6}, shortjournal = {The Astrophys. J.}, title = {Active galactic nucleus feedback-induced stellar density expansion in the inner regions of early-type galaxies}, volume = {990}, year = {2025}, }
• (2025). The role of pickup ions in the interaction of the solar wind with the local interstellar medium. II. effects of solar cycle. ApJ, 990(1), 5. (www)

  @article{ , abstract = {We investigate the role of pickup ions (PUIs) in the interaction of a periodically varying solar wind (SW) with the local interstellar medium (LISM). The analysis is performed using a 3D, time-dependent, multifluid model, where PUIs are treated as a separate fluid. The description of PUIs crossing the heliospheric termination shock utilizes results of kinetic simulations incorporated into magnetohydrodynamic (MHD) simulations. Space-time distributions of PUI properties throughout the heliosphere are presented. PUIs exhibit an intriguing behavior in the distant heliotail, where they are mostly concentrated in the vicinity of the heliopause (HP). Our simulations show that, because of the plasma mixing and MHD instabilities, PUIs created in the supersonic SW can cross the HP and enter the LISM. We find that the HP instability and solar cycle cause time-dependent variations in the flow of interstellar neutral atoms. When treated as a separate fluid, PUIs make the heliosphere slimmer, while the SW flow pattern in the heliotail exhibits enhanced variability. The simulation results are validated against in situ observations from the Voyager and New Horizons spacecraft.}, archive = {J_ApJ}, author = {R. K. Bera and F. Fraternale and N. V. Pogorelov and V. Roytershteyn and M. Gedalin and G. P. Zank}, doi = {10.3847/1538-4357/adec86}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {5}, shortjournal = {The Astrophys. J.}, title = {The role of pickup ions in the interaction of the solar wind with the local interstellar medium. II. effects of solar cycle}, volume = {990}, year = {2025}, }
• (2025). Investigating the impact of supernova feedback on satellites in elliptical galaxies. ApJ, 990(1), 4. (www)

  @article{ , abstract = {We investigate the influence of supernova (SN) feedback on the satellites of elliptical host galaxies using hydrodynamic simulations. Utilizing a modified version of the GADGET-3 code, we perform cosmological zoom-in simulations of 11 elliptical galaxies with stellar masses in the range 10 11 M ⊙ < M * < 2 × 10 11 M ⊙ . We conduct two sets of simulations with identical initial conditions: a fiducial model, which includes a three-phase SN mechanical wind, and a weak SN feedback model, where nearly all SN energy is released as thermal energy with a reduced SN wind velocity. Our comparison shows minimal differences in the elliptical host galaxies, but significant variations in the physical properties of satellite galaxies. The weak SN feedback model produces a larger number of satellite galaxies compared to the fiducial model, and significantly more than observed. For satellite galaxies with stellar masses above 10 8 M ⊙ , the weak SN feedback model generates approximately 5 times more satellites than observed in the Extending the Satellites Around Galactic Analogs Survey (or xSAGA) survey. Most of these overproduced satellites have small stellar masses, below 10 10 M ⊙ . Additionally, satellites in the weak SN feedback model are about 3.5 times more compact than those observed in the SAGA survey and the fiducial model, with metallicities nearly 1 dex higher than observed values. In conclusion, the satellite galaxies in the fiducial model, which includes mechanical SN feedback, exhibit properties that more closely align with observations. This underscores the necessity of incorporating both mechanical active galactic nuclei and SN feedback to reproduce the observed properties of elliptical galaxies and their satellites in simulations.}, archive = {J_ApJ}, author = {Sumi Kim and Ena Choi and Amanda C. N. Quirk and Rachel S. Somerville and Thorsten Naab and Jeremiah P. Ostriker and Michaela Hirschmann}, doi = {10.3847/1538-4357/adec96}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {4}, shortjournal = {The Astrophys. J.}, title = {Investigating the impact of supernova feedback on satellites in elliptical galaxies}, volume = {990}, year = {2025}, }
• (2025). BASS. XLIX. characterization of highly luminous and obscured AGNs: Local X-ray and [Ne v]λ3426 emission in comparison with the high-redshift universe. ApJ, 990(1), 3. (www)

  @article{ , abstract = {We present a detailed analysis of the most luminous and obscured active galactic nuclei (AGNs) detected in the ultra-hard X-ray band (14–195 kev) by the Swift/Burst Alert Telescope. Our sample comprises 21 X-ray luminous ( {\mathrm{log}}\,{L}_{{\rm{X}}}/{\rm{erg}}\,\,{{\rm{s}}}^{-1}\gt 44.6 , 2–10 keV) AGNs at z < 0.6, optically classified as Seyfert 1.9 and 2. Using NuSTAR, XMM-Newton, Suzaku, and Chandra data, we constrain AGN properties such as absorption column density N H , photon index Γ, intrinsic L X , covering factor, and iron K α equivalent width. We find median line-of-sight {\mathrm{log}}\,{N}_{{\rm{H}}}/{{\rm{cm}}}^{-2}=23.{5}_{-1.2}^{+0.5} and 2–10 keV rest-frame, de-absorbed {\mathrm{log}}\,{L}_{{\rm{X}}}/{\rm{erg}}\,\,{{\rm{s}}}^{-1}=44.{7}_{-0.6}^{+0.8} , at the 5th and 95th percentiles. For sources with black hole mass estimates (12/20), we find a weak correlation between Γ and Eddington ratio ( λ Edd ). Of these, six (50% ± 13%) lie in the N H - λ Edd “forbidden region” and exhibit a combined higher prevalence of N H variability and outflow signatures, suggesting a transitional phase where AGN feedback may be clearing the obscuring material. For the 13/21 sources with multi-epoch X-ray spectroscopy, {85}_{-15}^{+5} \% exhibit variability in either 2–10 keV flux ( {77}_{-15}^{+8} \% ) or line-of-sight N H ( 3{3}_{-10}^{+15} \% ). For the 20/21 sources with available near-UV/optical spectroscopy, we detect [Ne v] λ 3426 in 17 ( 8{5}_{-11}^{+5} %), confirming its reliability to probe AGN emission even in heavily obscured systems. When renormalized to the same [O iii ] λ 5007 peak flux as z = 2−9 narrow-line AGNs identified with JWST, our sample exhibits significantly stronger [Ne v] λ 3426 emission, suggesting that high-redshift obscured AGNs may be intrinsically weaker in [Ne v] λ 3426 or that [Ne v] λ 3426 is more challenging to detect in those environments. The sources presented in this work serve as a benchmark for high-redshift analogs, showing the potential of [Ne v] λ 3426 to reveal obscured AGNs and the need for future missions to expand X-ray studies into the high-redshift Universe.}, archive = {J_ApJ}, author = {Alessandro Peca and Michael J. Koss and Kyuseok Oh and Claudio Ricci and Benny Trakhtenbrot and Richard Mushotzky and Ezequiel Treister and C. Megan Urry and Andrealuna Pizzetti and Kohei Ichikawa and Alessia Tortosa and Federica Ricci and Matilde Signorini and Darshan Kakkad and Chin-Shin Chang and Giovanni Mazzolari and Turgay Caglar and Macon Magno and Ignacio del Moral-Castro and Peter G. Boorman and Tonima T. Ananna and Fiona Harrison and Daniel Stern and David Sanders}, doi = {10.3847/1538-4357/adec9a}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {3}, shortjournal = {The Astrophys. J.}, title = {BASS. XLIX. characterization of highly luminous and obscured AGNs: Local X-ray and [Ne v]λ3426 emission in comparison with the high-redshift universe}, volume = {990}, year = {2025}, }
• (2025). Supervised extraction of the thermal Sunyaev–Zel’dovich effect with a three-dimensional convolutional neural network. ApJ, 990(1), 2. (www)

  @article{ , abstract = {The thermal Sunyaev–Zel’dovich (SZ) effect offers a unique probe of the hot and diffuse Universe that could help close the missing baryon problem. Traditional extractions of the SZ effect, however, exhibit systematic noise that may lead to unreliable results. In this work, we provide an alternative solution using a 3D attention nested U-Net trained end to end with supervised learning. Our labeled data consist of simulated SZ signals injected into Planck frequency maps, allowing our model to learn how to extract SZ signals in the presence of realistic noise. We implement a curriculum learning scheme that gradually exposed the model to weaker SZ signals. The absence/presence of curriculum learning significantly impacted the amount of bias and variance present in the reconstructed SZ signal. The results from our method were comparable to those from the popular needlet internal linear combination method when evaluated on simulated data as well as real-world SZ signals. We conclude by discussing future avenues for advancing machine learning extractions of SZ signals.}, archive = {J_ApJ}, author = {Cameron T. Pratt and Zhijie Qu and Joel N. Bregman}, doi = {10.3847/1538-4357/adf069}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {2}, shortjournal = {The Astrophys. J.}, title = {Supervised extraction of the thermal Sunyaev–Zel’dovich effect with a three-dimensional convolutional neural network}, volume = {990}, year = {2025}, }
• (2025). Simultaneously excited narrow and broad quasiperiodic fast-propagating wave trains in the solar corona. ApJ, 990(1), 1. (www)

  @article{ , abstract = {The response of a solar coronal plasma loop to an impulsive perturbation, demonstrating the simultaneous formation of guided and leaky fast magnetoacoustic wave trains, is numerically studied. The equilibrium magnetic configuration corresponds to a potential arcade. A loop is modeled by filling a bent magnetic flux bundle with a plasma denser than in the surrounding. The plasma parameter β is much lower than unity everywhere in the computational domain. The initial perturbation is a pulse of the plasma velocity of sausage symmetry. The extent of the velocity pulse along the field is about the minor diameter of the loop. The perturbation generates both a guided fast-mode disturbance along the loop and leaky fast waves that propagate outward into the ambient corona. Both guided and leaky fast waves are quasiperiodic. The external component experiences refraction, which, in the chosen equilibrium, turns the wave toward the vertical. The guided component consists of a leading dispersive precursor, composed predominantly of higher harmonics, followed by a trailing wave train, dominated by the fundamental harmonic. In the external medium, the higher harmonic precursor generates leaky fast perturbations, while perturbations in the trailing wave train are evanescent. Our results confirm that both narrow and broad quasiperiodic fast-propagating waves detected in the corona can be excited by the same spatially localised impulsive energy deposition. The narrow counterpart is associated with the guided component, while the broad component is caused by the leaky component.}, archive = {J_ApJ}, author = {Mijie Shi and Valery M. Nakariakov and Bo Li and Mingzhe Guo}, doi = {10.3847/1538-4357/adf647}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {1}, shortjournal = {The Astrophys. J.}, title = {Simultaneously excited narrow and broad quasiperiodic fast-propagating wave trains in the solar corona}, volume = {990}, year = {2025}, }
• (2025). Erratum: “Filamentary hierarchies and superbubbles. i. characterizing filament properties across a simulated spiral galaxy” (2025 ApJ 987, 20). ApJ, 989(2), 233. (www)

  @article{ , archive = {J_ApJ}, author = {Rachel Pillsworth and Erica Roscoe and Ralph E. Pudritz and Eric W. Koch}, doi = {10.3847/1538-4357/adf62c}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {233}, shortjournal = {The Astrophys. J.}, title = {Erratum: “Filamentary hierarchies and superbubbles. i. characterizing filament properties across a simulated spiral galaxy” (2025 ApJ 987, 20)}, volume = {989}, year = {2025}, }
• (2025). Erratum: “Excitation of polycyclic aromatic hydrocarbon emission: Dependence on size distribution, ionization, and starlight spectrum and intensity” (2021, ApJ, 917, 3). ApJ, 989(2), 232. (www)

  @article{ , archive = {J_ApJ}, author = {B. T. Draine and Aigen Li and Brandon S. Hensley and L. K. Hunt and K. Sandstrom and J.-D. T. Smith}, doi = {10.3847/1538-4357/adf737}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {232}, shortjournal = {The Astrophys. J.}, title = {Erratum: “Excitation of polycyclic aromatic hydrocarbon emission: Dependence on size distribution, ionization, and starlight spectrum and intensity” (2021, ApJ, 917, 3)}, volume = {989}, year = {2025}, }
• (2025). New determination of the 14C(n, γ)15C reaction rate and its astrophysical implications. ApJ, 989(2), 231. (www)

  @article{ , abstract = {We present a novel experiment to investigate the spectroscopic factor (SF) of the 15 C ground state for the first time using single-neutron removal transfer reactions on 15 C. Two consistent SFs were derived from the (p, d) and (d, t) reactions, which were subsequently used to deduce the 14 C(n, γ ) 15 C reaction cross section and the corresponding stellar reaction rate. A typical cross section of 3.89 ± 0.76 μ b is determined at {E}_{{}_{{\rm{c}}.{\rm{m}}.}} = 23.3 keV. At the temperature range of 0.01–4 GK, our new reaction rate is 2.4–3.7 times higher than that of the first direct measurement and 20%–25% lower than that of the most recent direct measurement. Moreover, it is interesting that we can associate a long-standing nuclear structure issue, i.e., the so-called “quenching” effect, with this astrophysically relevant reaction. Finally, motivated by astrophysical interests of this reaction decades ago, implications of our new rate for several astrophysical problems are evaluated using state-of-the-art theoretical models. Our calculations demonstrate that the abundances of 14 N and 15 N can be enhanced in the inner regions of asymptotic giant branch stars, though with minimal impact on the chemical compositions of the interstellar medium. In the inhomogeneous Big Bang nucleosynthesis, the updated reaction rate can lead to a ∼20% variation in the final yields of 15 N in neutron-rich regions. For the r -process in the core-collapse supernovae, a slight difference of ∼0.2% in the final abundances of heavy elements with A > 90 can be found by using our new rate.}, archive = {J_ApJ}, author = {Yuchen Jiang and Zhenyu He and Yudong Luo and Wenyu Xin and Jie Chen and Xinyue Li and Yangping Shen and Bing Guo and Guo Li and Danyang Pang and Tianli Ma and Weike Nan and Toshitaka Kajino and Weiping Liu}, doi = {10.3847/1538-4357/ade5b3}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {231}, shortjournal = {The Astrophys. J.}, title = {New determination of the 14C(n, γ)15C reaction rate and its astrophysical implications}, volume = {989}, year = {2025}, }
• (2025). Powerful nuclear outflows and circumgalactic medium shocks driven by the most luminous known obscured quasar in the universe. ApJ, 989(2), 230. (www)

  @article{ , abstract = {We report integral field spectroscopy observations with the Near-Infrared Spectrograph on board the James Webb Space Telescope, targeting the 60 kpc environment surrounding the most luminous obscured quasar known at z = 4.6. We detect ionized gas filaments on 40 kpc scales connecting a network of merging galaxies, likely to form a cluster. We find regions of low ionization consistent with large-scale shock excitation surrounding the central dust-obscured quasar, out to distances nearly 8 times the effective stellar radius of the quasar host galaxy. In the nuclear region, we find an ionized outflow driven by the quasar with velocities reaching 13,000 km s −1 , one of the fastest discovered to date, with an outflow rate of 2000 M ⊙ yr −1 and a kinetic luminosity of 6 × 10 46 erg s −1 , resulting in a coupling efficiency between the bolometric luminosity of the quasar and the outflow of 5%. The kinetic luminosity of the outflow is sufficient to power the turbulent motion of the gas on galactic and circumgalactic scales, and is likely the primary driver of the radiative shocks on interstellar medium and circumgalactic medium scales. This provides compelling evidence supporting long-standing theoretical predictions that powerful quasar outflows are a main driver in regulating the heating and accretion rate of gas onto massive central cluster galaxies.}, archive = {J_ApJ}, author = {Andrey Vayner and Tanio Díaz-Santos and Peter R. M. Eisenhardt and Daniel Stern and Lee Armus and Daniel Anglés-Alcázar and Roberto J. Assef and Román Fernández Aranda and Andrew W. Blain and Hyunsung D. Jun and Chao-Wei Tsai and Niranjan Chandra Roy and Drew Brisbin and Carl D. Ferkinhoff and Manuel Aravena and Jorge González-López and Guodong Li and Mai Liao and Devika Shobhana and Jingwen Wu and Dejene Zewdie}, doi = {10.3847/1538-4357/addbdd}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {230}, shortjournal = {The Astrophys. J.}, title = {Powerful nuclear outflows and circumgalactic medium shocks driven by the most luminous known obscured quasar in the universe}, volume = {989}, year = {2025}, }
• (2025). Exploring the accretion Disk/Corona connection in NGC 6814: Insights from UV and X-ray spectral-timing studies. ApJ, 989(2), 229. (www)

  @article{ , abstract = {We conducted a comprehensive spectral and timing analysis of NGC 6814 using AstroSat’s 2019 and XMM-Newton’s 2021 observations. A cross-correlation analysis revealed a significant correlation between far-UV (1541 Å)/X-ray and UVW1 (2910 Å)/X-ray variations, with delays of ∼15 ks and 30 ks, respectively. We constructed four broadband spectral energy distributions (SEDs) after applying aperture correction (for the Ultra-Violet Imaging Telescope filter), subtracting host galaxy and emission-line contributions from UV flux, and using mean X-ray spectra alongside selected UV data points. First, we fitted the SEDs with the kynsed model, assuming various combinations of inclination θ , color correction factors f col , and black hole spins. Best-fit models were achieved for θ = 70° (consistent with past estimates for this source) and for spin ≤0.5, while f col is not constrained. kynsed provided a satisfactory fit to all SEDs in the case when the corona is powered by the accretion process, with ∼10%–20% of the accretion power transferred to the corona, \dot{m}/{\dot{m}}_{{\rm{Edd}}}\sim 0.1 , a corona radius of ∼6–10 r g , and a height of ∼7.5–35 r g . Model time lags computed using the SED best-fit results are aligned well with the observed time lags. Although some of the model parameters are not constrained, the important result of our work is that both the broadband X-ray/UV spectra and the X-ray/UV time lags in NGC 6814 are consistent with the hypothesis of X-ray illumination of the disk in a lamp-post geometry framework. Within this model framework, we do not need to assume an outer or inner truncated disk.}, archive = {J_ApJ}, author = {Kavita Kumari and I. E. Papadakis and G. C. Dewangan}, doi = {10.3847/1538-4357/ade05c}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {229}, shortjournal = {The Astrophys. J.}, title = {Exploring the accretion Disk/Corona connection in NGC 6814: Insights from UV and X-ray spectral-timing studies}, volume = {989}, year = {2025}, }
• (2025). Pulsar cyclic spectroscopy in the partial-deconvolution regime: Benefits and limitations. ApJ, 989(2), 228. (www)

  @article{ , abstract = {We explore possible advantages of cyclic spectroscopy for observations of pulsars in instances where full cyclic deconvolution is not possible. We compute cyclic merits and full-deconvolution regime boundaries for pulsars observed by NANOGrav and discuss which sources stand to benefit the most from using cyclic spectroscopy when observed with the Green Bank Telescope and DSA-2000 in a given frequency range. We compare data products, namely the wavefield, in both full-deconvolution and partial-deconvolution regimes to demonstrate what can be accomplished with incomplete phase retrieval. Additionally, we show how some phase retrieval can still be achieved in the partial-deconvolution regime and how this allows for additional information in scintillation-based data products, like the dynamic wavefield power, compared to what can be found in traditional dynamic spectra. An examination of dynamic wavefield phase as a function of observing frequency reveals more complete phase retrieval is achieved the closer one gets to the full-deconvolution regime, agreeing with the expectations of cyclic merit. While we demonstrate that fragmentary recovery of the secondary wavefield can be accomplished in the partial-deconvolution regime, we advocate for a synergistic approach with phase retrieval methods like the θ − θ transform, although we also provide discussion about shortcomings of this strategy. Finally, we use the combination of modest cyclic merit and lack of discernible results for PSR J1903+0327 to motivate the creation of an updated “cyclic merit 2.0,” which relies on scintillation bandwidth instead of observing bandwidth.}, archive = {J_ApJ}, author = {Jacob E. Turner and Timothy Dolch and Paul B. Demorest and Ryan S. Lynch and Daniel R. Stinebring and Cody Jessup and Nathaniel Jones and Christopher Scheithauer}, doi = {10.3847/1538-4357/adec73}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {228}, shortjournal = {The Astrophys. J.}, title = {Pulsar cyclic spectroscopy in the partial-deconvolution regime: Benefits and limitations}, volume = {989}, year = {2025}, }
• (2025). The population of NuSTAR black hole X-ray binaries. ApJ, 989(2), 227. (www)

  @article{ , abstract = {The spin of a black hole (BH) encodes information about its formation and evolution history. Yet the understanding of the distribution of BH spins in X-ray binaries (XBs), of the models used to measure spin, and of their impact on systematic uncertainties remains incomplete. In this work, we expand on previous analyses of the entire NuSTAR archive of accreting BH XBs. Prior work compiled a sample of 245 spectral fits using the relativistic reflection method for NuSTAR observations of 36 BH systems. Here, we aim to probe two aspects: the connection between BH spin and binary system properties, and the relationships between parameters in the spectral fits. We identify moderate negative correlations between spin uncertainty and both BH mass and system inclination, and a moderate positive correlation with distance. We also point out tentative multidimensional degeneracies between inclination, disk density, Fe abundance, ionization, and the presence or absence of absorption features from ionized outflows linked to disk winds. Lastly, we provide a comprehensive view of the observed distribution of BH spins in XBs, in comparison to spins inferred from gravitational waves. We find that the distribution of BH spins in XBs can be described by a beta distribution with α = 5.66 and β = 1.09. This data set is highly complex, and the analysis presented here does not fully explore all potential parameter correlations. We make the full data set available in Zenodo to the community to encourage further exploration.}, archive = {J_ApJ}, author = {Paul A. Draghis and Jon M. Miller and Laura Brenneman and Elisa Costantini and Luigi C. Gallo and Mark Reynolds and John A. Tomsick and Abderahmen Zoghbi}, doi = {10.3847/1538-4357/adec85}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {227}, shortjournal = {The Astrophys. J.}, title = {The population of NuSTAR black hole X-ray binaries}, volume = {989}, year = {2025}, }
• (2025). Robustness of neural ratio and posterior estimators to distributional shifts for population-level dark matter analysis in strong gravitational lensing. ApJ, 989(2), 226. (www)

  @article{ , abstract = {We investigate the robustness of neural ratio estimators (NREs) and sequential neural posterior estimators (SNPEs) to distributional shifts in the context of measuring the abundance of dark matter subhalos using strong gravitational lensing data. While these data-driven inference frameworks can be accurate on test data from the same distribution as the training sets, in real applications, it is expected that simulated training data and true observational data will differ in their distributions. We explore the behavior of a trained NRE and trained SNPEs to estimate the population-level parameters of dark matter subhalos from a large sample of images of strongly lensed galaxies with test data presenting distributional shifts within and beyond the bounds of the training distribution in the nuisance parameters (e.g., the background source morphology). While our results show that NREs and SNPEs perform well when tested perfectly in distribution, they exhibit significant biases that often lead to not recovering the ground truth in the 3 σ interval when confronted with slight deviations from the examples seen in the training distribution. This indicates the necessity for caution when applying NREs and SNPEs to real astrophysical data, where high-dimensional underlying distributions are not perfectly known.}, archive = {J_ApJ}, author = {Andreas Filipp and Yashar Hezaveh and Laurence Perreault-Levasseur}, doi = {10.3847/1538-4357/adee20}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {226}, shortjournal = {The Astrophys. J.}, title = {Robustness of neural ratio and posterior estimators to distributional shifts for population-level dark matter analysis in strong gravitational lensing}, volume = {989}, year = {2025}, }
• (2025). Frequency characteristics of magnetosonic waves driven by hot ring-beam protons. ApJ, 989(2), 225. (www)

  @article{ , abstract = {Magnetosonic (MS) waves can be generated by energetic ring-beam protons, appearing as harmonics near the local proton cyclotron frequency, in the planetary ionospheres/magnetospheres. A theoretical dispersion relation is derived using kinetic theory to study the growth and frequency characteristics of these locally generated MS waves in a background of cold plasma consisting of electrons, protons, and heavier ions such as atomic and molecular oxygen ions. The real frequencies and linear growth rates are calculated numerically by choosing parameters relevant to the Martian dayside upper ionosphere, where ring-beam generated MS waves have been previously reported. The study reveals that the ring component plays a dominant role in determining the growth or damping rates of the waves, while the beam component shifts the growth peaks of each harmonic farther away from integer multiples of the local proton cyclotron frequency. This frequency shift is influenced by the harmonic number, beam energy, and propagation angle. An increase in harmonic number and beam energy increases the shift, which is further enhanced as the propagation angle deviates from 90°. While the numerical results are specific to Martian parameters, the theoretical framework presented here provides a generalized description of MS waves driven by hot ring-beam protons, relevant to diverse space plasma environments.}, archive = {J_ApJ}, author = {Amrutha and S. V. Singh and K. C. Barik and G. S. Lakhina}, doi = {10.3847/1538-4357/adee90}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {225}, shortjournal = {The Astrophys. J.}, title = {Frequency characteristics of magnetosonic waves driven by hot ring-beam protons}, volume = {989}, year = {2025}, }
• (2025). The Gap–Giant association: Are planets hiding in the gaps?. ApJ, 989(2), 224. (www)

  @article{ , abstract = {A handful of stars are known to host both an inner system of multiple transiting planets and an outer giant planet. These systems all feature a prominent gap between the orbits of two of the transiting planets, distinguishing them from typical multiplanet systems with more uniform orbital spacings. The reason for the association between inner gaps and outer giants is unknown. In this paper, we assess whether undiscovered planets might occupy these gaps in systems with outer giants. For each of the four relevant systems—Kepler-48, Kepler-65, Kepler-90, and Kepler-139—we found that a typical small planet (∼1–20 M ⊕ ) could reside in the gap without inducing dynamical instability. However, in each case the gravitational influence of the outer giant planet is insufficient to tilt the orbit of the hypothetical planet by enough to prevent transits, strongly disfavoring a proposed theory for the observed gap–giant association. The gaps might instead contain smaller, undetected planets (≲ 1 R ⊕ ), or be entirely devoid of planets.}, archive = {J_ApJ}, author = {Caleb Lammers and Joshua N. Winn}, doi = {10.3847/1538-4357/adf06b}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {224}, shortjournal = {The Astrophys. J.}, title = {The Gap–Giant association: Are planets hiding in the gaps?}, volume = {989}, year = {2025}, }
• (2025). MeerKAT 1.3 GHz observations of the wide-angle tail radio galaxy j1712–2435. ApJ, 989(2), 223. (www)

  @article{ , abstract = {We present full-polarization MeerKAT images of the wide-angle tail, giant radio galaxy J1712−2435 at 1.3 GHz with 7 \mathop{.}\limits^{\unicode{x02033}} 5 resolution and an rms sensitivity of 8 μ Jy beam −1 . Due to its angular proximity to the Galactic center ( l = 359 \mathop{.}\limits^{\unicode{x000b0}} 6, b = +8 \mathop{.}\limits^{\unicode{x000b0}} 5), the immediate environment is not well understood, but there are massive clusters nearby. Emission can be traced over an extent of 34 \mathop{.}\limits^{{\rm{^{\prime} }}} 6, which at the redshift of 0.024330 corresponds to a projected length of 1.02 Mpc. The inner jets are quite straight, but then bend and completely decollimate into extended plumes nearly orthogonal to the initial jet directions at a projected distance of approximately 100 kpc. The near-unity brightness ratio of the inner jets suggest that they are orientated within a few degrees of the plane of the sky. The 1400 MHz power is 3.9 × 10 24 W Hz −1 , somewhat below the FRI/FRII divide. The total power emitted is estimated to be 5.6 × 10 41 erg s −1 over the range 10 MHz–100 GHz. The source dynamics are modeled with magnetohydrodynamics simulations; the result is a rough reproduction of the source’s radio morphology/appearance. This study further highlights the merit of alternative scenarios, calling for future observational and numerical efforts.}, archive = {J_ApJ}, author = {W. D. Cotton and Gourab Giri and P. J. Agnihotri and D. J. Saikia and K. Thorat and F. Camilo}, doi = {10.3847/1538-4357/adf186}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {223}, shortjournal = {The Astrophys. J.}, title = {MeerKAT 1.3 GHz observations of the wide-angle tail radio galaxy j1712–2435}, volume = {989}, year = {2025}, }
• (2025). Generation of surface sausage oscillations of a current sheet and propagating magnetoacoustic waves by impulsive reconnection. ApJ, 989(2), 222. (www)

  @article{ , abstract = {Magnetic reconnection and magnetohydrodynamic waves may well be both playing a role in coronal heating. In this paper, we simulate reconnection in the corona as a response to the convergence of opposite-polarity magnetic sources at the base of the corona. A current sheet forms at a magnetic null and undergoes impulsive bursty reconnection, which drives natural modes of oscillation of the current sheet by a process of symbiosis. These are leaky surface sausage modes, which cause the length of the current sheet to oscillate. Interaction of the oscillations and reconnection outflows with the magnetic Y-points at the ends of the sheet acts as sources for magnetoacoustic waves. Fast-mode waves propagate outward into the coronal environment, while slow-mode waves propagate along the separatrices extending from the ends of the current sheet. The periodicities for sausage oscillations of the current sheet, for the current sheet length, and for the propagating large-scale magnetoacoustic waves are all estimated to be approximately 91 s for the parameters of our experiment.}, archive = {J_ApJ}, author = {Sripan Mondal and A. K. Srivastava and David I. Pontin and Eric R. Priest}, doi = {10.3847/1538-4357/adf18e}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {222}, shortjournal = {The Astrophys. J.}, title = {Generation of surface sausage oscillations of a current sheet and propagating magnetoacoustic waves by impulsive reconnection}, volume = {989}, year = {2025}, }
• (2025). High-resolution radio study of pulsar wind nebula MSH 15–52 and supernova remnant RCW 89. ApJ, 989(2), 221. (www)

  @article{ , abstract = {We present high-resolution radio observations of the pulsar wind nebula (PWN) MSH 15–5 2 , which is renowned for its distinctive handlike shape, and its associated supernova remnant RCW 89. Using the Australia Telescope Compact Array, we obtained 3 and 6 cm radio maps with a resolution of 2″. These unveil small-scale radio features in the system and allow a direct comparison with the arcsecond-resolution X-ray images. We find that the radio emission is composed of a complex filamentary structure. In particular, there is a bar-like feature across the central pulsar B1509−58 in the inner PWN, and the radio sheath wrapping around the pulsar also appears to be made up of filaments. Some prominent X-ray features are not detected in radio, including the one-sided jet in the south and the fingerlike structures in the north. These indicate turnover of the particle distribution at low energies in these regions. For RCW 89, the radio emission well coincides with both the X-ray knots and the H α filaments. The high polarization fraction shows that the emission is synchrotron in nature, but it extends well beyond the sharp boundary of the nonthermal X-ray emission, which is difficult to explain.}, archive = {J_ApJ}, author = {S. Zhang and C.-Y. Ng and N. Bucciantini}, doi = {10.3847/1538-4357/adf333}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {221}, shortjournal = {The Astrophys. J.}, title = {High-resolution radio study of pulsar wind nebula MSH 15–52 and supernova remnant RCW 89}, volume = {989}, year = {2025}, }
• (2025). Clump-fed black hole growth in the first billion years of the universe. ApJ, 989(2), 220. (www)

  @article{ , abstract = {Understanding how supermassive black holes (SMBHs) form in the early Universe is one of the most challenging problems in astrophysics. Their high abundance in the first billion years, as observed by the James Webb Space Telescope, hints toward black hole seeds that accrete mass rapidly. The origin of this accreted mass is not known. Here, we consider a billion solar mass clumpy galaxy at z = 5.48 with a 30 million solar mass black hole in the center. We show that the clumps should migrate to the central region because of torques from dynamical friction with the halo, funneling in at least 14 solar masses per year. This is fast enough to grow the observed SMBH, with only 1% of the accreted mass getting in and the rest going to a bulge. Clump-fed accretion could explain most young SMBHs because young galaxies are highly irregular with massive star-forming clumps.}, archive = {J_ApJ}, author = {Manish Kataria and Kanak Saha and Bruce Elmegreen}, doi = {10.3847/1538-4357/adcebc}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {220}, shortjournal = {The Astrophys. J.}, title = {Clump-fed black hole growth in the first billion years of the universe}, volume = {989}, year = {2025}, }
• (2025). From UV-bright galaxies to early disks: The importance of turbulent star formation in the early universe. ApJ, 989(2), 219. (www)

  @article{ , abstract = {Bursty star formation at early times can explain the surprising abundance of early UV-bright galaxies revealed by JWST but can also be a reason for the delayed formation of galactic disks in high-resolution cosmological simulations. We investigate this interplay in a cosmological simulation of an early-forming Milky Way analog with detailed modeling of the cold turbulent interstellar medium (ISM), star formation, and feedback. We find that the modeling of locally variable star formation efficiency (SFE) coupled with the ISM turbulence on the scales of star-forming regions is important for producing both early bursty evolution and early formation and survival of galactic disks. Such a model introduces a qualitatively new channel of the global star formation rate (SFR) burstiness caused by chaotic fluctuations in the average SFE due to changes in the ISM turbulence, which, in our simulation, dominates the short-term SFR variability. The average SFE stays low, close to ∼1% per freefall time, and its variation decreases when the gas disk forms, leading to only mild effects of stellar feedback on the early disk, enabling its survival. By rerunning our simulation with fixed SFE values, we explicitly show that low SFEs lead to smoother SFR histories and disk survival, while high SFEs lead to bursty SFRs and hinder disk formation. The model with variable SFE switches between these two regimes at the moment of disk formation. These trends are missing in more commonly used star formation prescriptions with fixed SFE; in particular, the prescriptions tying star formation to molecular gas should be interpreted with caution because the two are decoupled at early times, as we also show in this paper.}, archive = {J_ApJ}, author = {Vadim A. Semenov and Charlie Conroy and Lars Hernquist}, doi = {10.3847/1538-4357/ade22d}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {219}, shortjournal = {The Astrophys. J.}, title = {From UV-bright galaxies to early disks: The importance of turbulent star formation in the early universe}, volume = {989}, year = {2025}, }
• (2025). How do uncertainties in galaxy formation physics impact field-level galaxy bias?. ApJ, 989(2), 218. (www)

  @article{ , abstract = {Our ability to extract cosmological information from galaxy surveys is limited by uncertainties in the galaxy–dark matter halo relationship for a given galaxy population, which are governed by the intricacies of galaxy formation. To quantify these uncertainties, we examine quenched and star-forming galaxies using two distinct approaches to modeling galaxy formation: U niverse M achine , an empirical semianalytic model, and the I llustris TNG hydrodynamical simulation. We apply a second-order hybrid N -body perturbative bias expansion to each galaxy sample, enabling direct comparison of modeling approaches and revealing how uncertainties in the galaxy–halo connection affect bias parameters and non-Poisson noise across number densities and redshifts. Notably, we find that quenched and star-forming galaxies occupy distinct parts of the bias parameter space, and that the scatter induced from these different galaxy formation models is small when conditioned on similar selections of galaxies. We also detect the signature of assembly bias in our samples; this leads to small but significant deviations from analytic bias predictions, while assembly bias-removed samples match these predictions well. This work indicates that galaxy samples from a spectrum of reasonable, physically motivated models for galaxy formation give a relatively small range of field-level galaxy bias parameters. We estimate a set of priors from these models that should be useful in extracting cosmological constraints from luminous red galaxy– and emission line galaxy–like samples. Looking forward, careful estimates of the range of impacts of galaxy formation, for a given sample and cosmological analysis, will be an essential ingredient for extracting the most precise cosmological information from current and future large galaxy surveys.}, archive = {J_ApJ}, author = {Mahlet Shiferaw and Nickolas Kokron and Risa H. Wechsler}, doi = {10.3847/1538-4357/ade66e}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {218}, shortjournal = {The Astrophys. J.}, title = {How do uncertainties in galaxy formation physics impact field-level galaxy bias?}, volume = {989}, year = {2025}, }
• (2025). Machine learning approach for estimating magnetic field strength in galaxy clusters from synchrotron emission. ApJ, 989(2), 217. (www)

  @article{ , abstract = {Magnetic fields play a crucial role in various astrophysical processes within the intracluster medium, including heat conduction, cosmic-ray acceleration, and the generation of synchrotron radiation. However, measuring magnetic field strength is typically challenging due to the limited availability of Faraday rotation measure sources. To address the challenge, we propose a novel method that employs Convolutional Neural Networks (CNNs) alongside synchrotron emission observations to estimate magnetic field strengths in galaxy clusters. Our CNN model is trained on either magnetohydrodynamic (MHD) turbulence simulations or MHD galaxy cluster simulations, which incorporate complex dynamics such as cluster mergers and sloshing motions. The results demonstrate that CNNs can effectively estimate magnetic field strengths with mean-squared error of approximately 0.135 µ G 2 , 0.044 µ G 2 , and 0.02 µ G 2 for β = 100, 200, and 500 conditions, respectively. Additionally, we have confirmed that our CNN model remains robust against noise and variations in viewing angles with sufficient training, ensuring reliable performance under a wide range of observational conditions. We compare the CNN approach with the traditional magnetic field strength estimate method that assumes equipartition between cosmic-ray electron energy and magnetic field energy. In contrast to the equipartition method, this CNN approach relies on the morphological feature of synchrotron images, offering a new perspective for complementing traditional estimates and enhancing our understanding of cosmic-ray acceleration mechanisms.}, archive = {J_ApJ}, author = {Jiyao Zhang and Yue Hu and Alex Lazarian}, doi = {10.3847/1538-4357/adeb7a}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {217}, shortjournal = {The Astrophys. J.}, title = {Machine learning approach for estimating magnetic field strength in galaxy clusters from synchrotron emission}, volume = {989}, year = {2025}, }
• (2025). UVIT study of the magellanic clouds (U-SMAC). III. hierarchical star formation in the small magellanic cloud regulated by turbulence. ApJ, 989(2), 216. (www)

  @article{ , abstract = {The Small Magellanic Cloud (SMC), a satellite galaxy of the Milky Way, is an irregular dwarf galaxy exhibiting evidence of recent and ongoing star formation. We performed a spatial clustering analysis of far-ultraviolet stars in the SMC younger than 150 Myr using data from the Ultra Violet Imaging Telescope on board AstroSat. We identified 236 young stellar structures as surface overdensities at different significance levels. The sizes of these structures range from a few parsecs to several hundred parsecs. Their irregular morphologies are characterized by a perimeter–area dimension, derived from the projected boundaries of the young stellar structures, of D p = 1.46 ± 0.4. The 2D fractal dimensions obtained from, respectively, the number–size relation and the size distribution are D 2 = 1.64 ± 0.03 and D 2 = 1.31 ± 0.16. These values indicate significant lumpiness among the young stellar structures. In addition, the surface density distribution of the identified structures follows a log-normal distribution. These features are strikingly similar to those of the turbulent interstellar medium, thus supporting the scenario of hierarchical star formation regulated by supersonic turbulence.}, archive = {J_ApJ}, author = {Sipra Hota and Richard de Grijs and Annapurni Subramaniam}, doi = {10.3847/1538-4357/adec84}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {216}, shortjournal = {The Astrophys. J.}, title = {UVIT study of the magellanic clouds (U-SMAC). III. hierarchical star formation in the small magellanic cloud regulated by turbulence}, volume = {989}, year = {2025}, }
• (2025). The contribution of turbulent active galactic nucleus coronae to the diffuse neutrino flux. ApJ, 989(2), 215. (www)

  @article{ , abstract = {Active galactic nuclei (AGN) can accelerate protons to energies of ∼10–100 TeV, with secondary production of high-energy neutrinos. If the acceleration is driven by magnetized turbulence, the main properties of the resulting proton and neutrino spectra can be deduced based on insights from particle-in-cell simulations of magnetized turbulence. We have previously shown that these properties are consistent with the TeV neutrino signal observed from the nearby active galaxy NGC 1068. In this work, we extend this result to a population study. We show that the produced neutrino flux depends mainly on the energetics of the corona—the relative fractions of X-ray, magnetic, and nonthermal proton energy—and on the spectral energy distribution of the AGN. We find that coronae with similar properties can explain neutrinos from the candidate AGN for which IceCube has reported an excess, albeit less significant than NGC 1068. Building on this framework, we show how the neutrino signal evolves with AGN luminosity, and use this AGN sequence to predict the diffuse neutrino flux from the extragalactic population, showing that it can account for the diffuse neutrino signal observed by IceCube in the ∼1–100 TeV energy range.}, archive = {J_ApJ}, author = {Damiano F. G. Fiorillo and Luca Comisso and Enrico Peretti and Maria Petropoulou and Lorenzo Sironi}, doi = {10.3847/1538-4357/adec9c}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {215}, shortjournal = {The Astrophys. J.}, title = {The contribution of turbulent active galactic nucleus coronae to the diffuse neutrino flux}, volume = {989}, year = {2025}, }
• (2025). Unveiling the galactic baryon cycle process by an empirical model. ApJ, 989(2), 214. (www)

  @article{ , abstract = {We propose an empirical model to describe and constrain the baryon cycle process during galaxy evolution. This model utilizes the evolution of star formation rate, derived from the stellar mass–halo mass relations across different redshifts, and the cold gas content, derived from the NeutralUniverseMachine model, to constrain gas accretion and recycle of gas outflow in the model galaxy. Additionally, through detailed modeling of each cycle process, particularly the recycling process, and utilizing the gas-phase mass–metallicity relation at z = 0 as a constraint, our model establishes a relation between the recycle fraction and halo mass. It is found that the fraction of gas recycled from the outflow is a function of halo mass, with a value of 25% in galaxies with a halo mass of ∼10 10.4 M ⊙ , increasing to 75% in halos with a mass of ∼10 12 M ⊙ . We also find that the mass loading factor from the FIRE-2 simulation matches well with the constraints from both observational data and our model. Furthermore, using the gas content and metallicity of the circumgalactic medium (CGM) obtained from hydrodynamical simulations as constraints, our model predicts that, on average, 70% of universal baryon accretion is accreted to the halo and 80% of the nonrecycled gas in the outflow has escaped from the galaxy, entering the intergalactic medium (IGM). However, we note that future observational data are needed to finally constrain the mass and metal exchange between the CGM and the IGM.}, archive = {J_ApJ}, author = {Yaoxin Chen and Xi Kang and Hong Guo and Hou-Zun Chen and Jiafeng Lu}, doi = {10.3847/1538-4357/aded10}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {214}, shortjournal = {The Astrophys. J.}, title = {Unveiling the galactic baryon cycle process by an empirical model}, volume = {989}, year = {2025}, }
• (2025). A detailed analysis of the milky way warp based on classical cepheids. ApJ, 989(2), 213. (www)

  @article{ , abstract = {Classical Cepheids (CCs) are important probes for the large-scale warp structure of the Milky Way. Using Gaia Data Release 3 CCs, we establish an optimal time-dependent warp model, where the warp height increases with radius following a power law, the line of nodes (LONs) exhibit linear twisting with radius, following a leading spiral pattern, and the LONs undergo prograde evolution over time. Structurally, we identify significant warp features in the 5–9 kpc region of the Galactic disk, where the warp model performs better than the flat model. Beyond 15 kpc, the model with the second Fourier term does not fit the observations well, whereas the model with twisted LONs better matches the data. Kinematically, we derive expressions for the vertical velocities using direct differentiation and then calculate the precession rates for each CC. Our results intuitively indicate a nearly uniform and low warp precession rate of ω = 4.86 ± (0.88) stat ± (2.14) sys km s −1 kpc −1 beyond 12.5 kpc, in agreement with classical kinematic estimates. Based on these findings, we propose a simple yet comprehensive time-dependent warp model, {Z}_{w}(t)=0.00019{R}^{3.08}\sin (\phi -(3.87R-41.79+4.86t)) , which provides a unified framework for describing both the geometric and kinematic evolution of the Galactic warp. We analyze the impact of the adopted solar vertical velocity on the inferred warp precession rate and confirm the reliability of the measured precession rate. In addition, we find that the extinction treatment affects the warp amplitude in the inner disk, while its influence on the outer-disk warp structure and the precession rate is negligible.}, archive = {J_ApJ}, author = {Xiaoyue Zhou and Xiaodian Chen and Licai Deng and Shu Wang and Jiyu Wang and Jianxing Zhang}, doi = {10.3847/1538-4357/adee1b}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {213}, shortjournal = {The Astrophys. J.}, title = {A detailed analysis of the milky way warp based on classical cepheids}, volume = {989}, year = {2025}, }
• (2025). Variable X-ray reverberation in the rapidly accreting active galactic nucleus ark 564: The response of the soft excess to the changing geometry of the inner accretion flow. ApJ, 989(2), 212. (www)

  @article{ , abstract = {X-ray reverberation, which exploits the time delays between variability in different energy bands as a function of Fourier frequency, probes the structure of the inner accretion disks and X-ray coronae of active galactic nuclei. We present a systematic X-ray spectroscopic and reverberation study of the high-Eddington-ratio narrow-line Seyfert 1 galaxy Ark 564, using over 900 ks of XMM-Newton and NuSTAR observations spanning 13 yr. The time-averaged spectra can be well described by a model consisting of a coronal continuum, relativistic disk reflection, warm Comptonization, and three warm absorbers. Leveraging the high X-ray brightness of Ark 564, we are able to resolve the time evolution of the spectra and contemporaneous reverberation lags. The soft-band lag relative to the continuum increases with the X-ray flux, while Fe K α lags are detected in only a subset of epochs and do not correlate with soft lags. Models based on a lamppost corona and reflection from a standard thin disk can broadly reproduce the observed lag-energy spectra of low-flux epochs; however, additional reverberation from the warm Comptonized atmosphere is required to explain the soft lags observed in high-flux epochs. A vertically puffed-up inner disk and a variable, vertically extended corona can better explain the observed evolution of the lags and covariance spectra. Our study underscores the importance of multiepoch, multiband analyses for a comprehensive understanding the inner accretion disk and corona.}, archive = {J_ApJ}, author = {Zhefu Yu and Dan Wilkins and Steven W. Allen}, doi = {10.3847/1538-4357/adef4f}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {212}, shortjournal = {The Astrophys. J.}, title = {Variable X-ray reverberation in the rapidly accreting active galactic nucleus ark 564: The response of the soft excess to the changing geometry of the inner accretion flow}, volume = {989}, year = {2025}, }
• (2025). Using polarization to uncover the lyα emission mechanism in lyα nebulae. ApJ, 989(2), 211. (www)

  @article{ , abstract = {“Ly α nebulae” are immense (∼100 kpc) glowing gas clouds located in the distant universe, and the origin of their extended Ly α emission remains a mystery. Mapping their polarization offers critical insights, but imaging polarimetry to date has revealed polarization patterns that are difficult to interpret due to differences in the types and spatial configurations of their embedded sources. In this study, we more than double the sample size of polarization observations by targeting four additional Ly α nebulae: 4C41.17, SSA22-Sb3-LAB1, JACKPOT, and MAMMOTH-1, all of which host active galactic nuclei (AGN), from radio-loud to radio-quiet to type-I to type-II. Significant polarization is detected in three of these four nebulae, with polarization vectors distributed across the extended Ly α -emitting gas. In the two Ly α nebulae hosting radio-loud AGN, the polarization vectors exhibit a preferential alignment perpendicular to the radio jet direction, suggesting a scattering origin related to AGN outflows. In 4C41.17, JACKPOT, and MAMMOTH-1 (3/4 cases), the polarization strength shows a possible trend of increasing with radius. While the spatial patterns are complex and most large-radius measurements are upper limits, our results—together with previous work on three other targets—support the idea that scattering plays a key role in shaping the Ly α emission from these nebulae. Full interpretation requires direct comparison of these observations to radiative transfer models over a wide range of parameter space.}, archive = {J_ApJ}, author = {Eunchong Kim and Yujin Yang and Sung-Joon Park and Ann Zabludoff and Paul Smith and Myung Gyoon Lee and Woong-Seob Jeong and Buell Jannuzi and Narae Hwang and Byeong-Gon Park}, doi = {10.3847/1538-4357/adef52}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {211}, shortjournal = {The Astrophys. J.}, title = {Using polarization to uncover the lyα emission mechanism in lyα nebulae}, volume = {989}, year = {2025}, }
• (2025). Modeling atmospheric alteration on titan: Hydrodynamics and shock-induced chemistry of meteoroid entry. ApJ, 989(2), 210. (www)

  @article{ , abstract = {Meteoroid entry into planetary atmospheres generates bow shocks, resulting in high-temperature gas conditions that drive chemical reactions. In this paper, we perform three-dimensional hydrodynamic simulations of meteoroid entry using the Athena++ code, coupled with chemistry calculations via Cantera to model the nonequilibrium chemistry triggered by atmospheric entry. Our aerodynamical simulations reveal the formation of complex shock structures, including secondary shock waves, which influence the thermodynamic evolution of the gas medium. By tracking thermodynamic parameters along streamlines, we analyze the effects of shock heating and subsequent expansion cooling on chemical reaction pathways. Our results demonstrate that chemical quenching occurs when the cooling timescale surpasses reaction rates, leading to the formation of distinct chemical products that deviate from equilibrium predictions. We show that the efficiency of molecular synthesis depends on the object’s size and velocity, influencing the composition of the post-entry gas mixture. Applying our model to Titan, we demonstrate that organic matter can be synthesized in the present environment of Titan. Also, we find that nitrogen, the dominant atmospheric component, remains stable, while water vapor is efficiently removed, a result inconsistent with equilibrium chemistry assumptions. Moreover, we compare our simulation results with laser experiments and find good agreement in chemical yields. Finally, we also evaluate the impact on Titan’s atmosphere as a whole, showing that meteoroid entry events could have played a significant role in supplying molecules such as HCN during early Titan’s history.}, archive = {J_ApJ}, author = {Ryushi Miyayama and Laura Kay Schaefer and Hiroshi Kobayashi and Andrea Zorzi}, doi = {10.3847/1538-4357/adf064}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {210}, shortjournal = {The Astrophys. J.}, title = {Modeling atmospheric alteration on titan: Hydrodynamics and shock-induced chemistry of meteoroid entry}, volume = {989}, year = {2025}, }
• (2025). The AURORA survey: The nebular attenuation curve of a galaxy at z = 4.41 from ultraviolet to near-infrared wavelengths. ApJ, 989(2), 209. (www)

  @article{ , abstract = {We use JWST/NIRSpec observations from the Assembly of Ultradeep Rest-optical Observations Revealing Astrophysics survey to constrain the shape of the nebular attenuation curve of a star-forming galaxy at z = 4.41, GOODSN-17940. We utilize 12 H i recombination lines to derive the attenuation curve spanning optical to near-infrared wavelengths (3751–9550 Å). We then leverage a high signal-to-noise ratio spectroscopic detection of the rest-frame ultraviolet continuum in combination with rest-UV photometric measurements to constrain the shape of the curve at ultraviolet wavelengths. While this UV constraint is predominantly based on stellar emission, the large measured equivalent widths of H α and H β indicate that GOODSN-17940 is dominated by an extremely young stellar population <10 Myr in age such that the UV stellar continuum experiences similar attenuation to that of the nebular emission. The resulting combined nebular attenuation curve spans 1400–9550 Å and has a shape that deviates significantly from commonly assumed dust curves in high-redshift studies. Relative to the Milky Way, SMC, and Calzetti curves, the new curve has a steeper slope at long wavelengths ( λ > 5000 Å) while displaying a similar slope across blue-optical wavelengths ( λ = 3750–5000 Å). In the ultraviolet, the new curve is shallower than the SMC and Calzetti curves and displays no significant 2175 Å bump. This work demonstrates that the most commonly assumed dust curves are not appropriate for all high-redshift galaxies. These results highlight the ability to derive nebular attenuation curves for individual high-redshift sources with deep JWST/NIRSpec spectroscopy, thereby improving the accuracy of physical properties inferred from nebular emission lines.}, archive = {J_ApJ}, author = {Ryan L. Sanders and Alice E. Shapley and Michael W. Topping and Naveen A. Reddy and Danielle A. Berg and Rychard J. Bouwens and Gabriel Brammer and Adam C. Carnall and Fergus Cullen and Romeel Davé and James S. Dunlop and Richard S. Ellis and N. M. Förster Schreiber and Steven R. Furlanetto and Karl Glazebrook and Garth D. Illingworth and Tucker Jones and Mariska Kriek and Derek J. McLeod and Ross J. McLure and Desika Narayanan and Pascal A. Oesch and Anthony J. Pahl and Max Pettini and Daniel Schaerer and Daniel P. Stark and Charles C. Steidel and Mengtao Tang and Leonardo Clarke and Callum T. Donnan and Emily Kehoe}, doi = {10.3847/1538-4357/adf066}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {209}, shortjournal = {The Astrophys. J.}, title = {The AURORA survey: The nebular attenuation curve of a galaxy at z = 4.41 from ultraviolet to near-infrared wavelengths}, volume = {989}, year = {2025}, }
• (2025). Polarization as a probe of neutrino emission from blazars. ApJ, 989(2), 208. (www)

  @article{ , abstract = {The source of extragalactic neutrinos in the TeV–PeV range is a matter of very active research, with blazar jets having been postulated to be the origin of at least some of the detections. The blazar PKS 0735+178 is a prominent example; during its multiband flare in late 2021, a neutrino event was reported by four observatories, with its origin consistent with the direction of that source. While no new jet component was observed to be ejected during that narrow time frame, our analysis shows that a propagating shock front originating from the core region was the likely source of the multiband flare, using very-long-baseline interferometry images of PKS 0735+178 in polarized light. Taken together, our findings are suggestive of a coherent scenario in which the shock may contribute to the acceleration of protons, with the target photons potentially originating either from the ambient medium surrounding the jet or from proton synchrotron radiation. The necessary conditions for neutrino emission via proton–photon interactions are, hence, present in this jet.}, archive = {J_ApJ}, author = {G. F. Paraschos and E. Traianou and L. C. Debbrecht and I. Liodakis and E. Ros}, doi = {10.3847/1538-4357/adf110}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {208}, shortjournal = {The Astrophys. J.}, title = {Polarization as a probe of neutrino emission from blazars}, volume = {989}, year = {2025}, }
• (2025). Field-level comparison and robustness analysis of cosmological N-body simulations. ApJ, 989(2), 207. (www)

  @article{ , abstract = {We present the first field-level comparison of cosmological N -body simulations, considering various widely used codes: Abacus, CUBEP 3 M, Enzo, Gadget, Gizmo, PKDGrav, and Ramses. Unlike previous comparisons focused on summary statistics, we conduct a comprehensive field-level analysis: evaluating statistical similarity, quantifying implications for cosmological parameter inference, and identifying the regimes in which simulations are consistent. We begin with a traditional comparison using the power spectrum, cross-correlation coefficient, and visual inspection of the matter field. We follow this with a statistical out-of-distribution (OOD) analysis to quantify distributional differences between simulations, revealing insights not captured by the traditional metrics. We then perform field-level simulation-based inference using convolutional neural networks (CNNs), training on one simulation and testing on others, including a full hydrodynamic simulation for comparison. We identify several causes of OOD behavior and biased inference, finding that resolution effects, such as those arising from adaptive mesh refinement (AMR), have a significant impact. Models trained on non-AMR simulations fail catastrophically when evaluated on AMR simulations, introducing larger biases than those from hydrodynamic effects. Differences in resolution, even when using the same N -body code, likewise lead to biased inference. We attribute these failures to a CNN’s sensitivity to small-scale fluctuations, in particular in voids and filaments, and demonstrate that appropriate smoothing brings the simulations into statistical agreement. Our findings motivate the need for careful data filtering and the use of field-level OOD metrics, such as PQMass, to ensure robust inference.}, archive = {J_ApJ}, author = {Adrian E. Bayer and Francisco Villaescusa-Navarro and Sammy Sharief and Romain Teyssier and Lehman H. Garrison and Laurence Perreault-Levasseur and Greg L. Bryan and Marco Gatti and Eli Visbal}, doi = {10.3847/1538-4357/adef4e}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {207}, shortjournal = {The Astrophys. J.}, title = {Field-level comparison and robustness analysis of cosmological N-body simulations}, volume = {989}, year = {2025}, }
• (2025). A study of spectral variability between flaring and nonflaring state in m74 X-1. ApJ, 989(2), 206. (www)

  @article{ , abstract = {We conducted an extensive long-term spectral and timing study of the ultraluminous X-ray (ULX) source M74 X-1, using data taken between 2001 and 2021 by Chandra and XMM-Newton X-ray observatories. Our analysis shows that flares are present in some observations, whereas they are absent in others. The flaring state exhibits two-component spectra at a lower average flux level, whereas the nonflaring state displays single-component spectra at a higher average flux level. The M74 X-1 spectra are best described by the combination of accretion disk and Comptonization components, dual thermal disk blackbody model, and a modified multitemperature disk blackbody model. Using the dual thermal disk blackbody model, we obtain cool and hot temperatures of T in (cool) = 0.3{8}_{-0.06}^{+0.08} keV and T in (hot) = 1.6{7}_{-0.13}^{+0.18} keV, respectively, suggesting two temperature emitting regions and indicating possible presence of outflowing wind along with the accretion disk. We found a Gaussian feature at E line = 0.9{6}_{-0.11}^{+0.05} keV with σ = 0.1{1}_{-0.06}^{+0.13} keV in the spectra of the flaring state, which can be interpreted as the unresolved wind feature in the system when compared to similar feature seen in other ULX sources. Plotting the hardness luminosity diagram, we get a trend of increasing hardness with luminosity, suggesting the presence of geometrical beaming in a low-inclination system. Additionally, using the hot disk blackbody component from the dual thermal disk blackbody model, we estimate the mass of the compact object to be M = 7.{1}_{-1.3}^{+1.4} M ⊙ , classifying it as a stellar-mass black hole and confirming super-Eddington accretion in the system.}, archive = {J_ApJ}, author = {Aman Upadhyay and Tanuman Ghosh and Vikram Rana}, doi = {10.3847/1538-4357/ade9b3}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {206}, shortjournal = {The Astrophys. J.}, title = {A study of spectral variability between flaring and nonflaring state in m74 X-1}, volume = {989}, year = {2025}, }
• (2025). Star formation and magnetic field amplification due to galactic spirals. ApJ, 989(2), 205. (www)

  @article{ , abstract = {We use global MHD galaxy simulations to investigate the effects of spiral arms on the evolution of magnetic fields and star formation within a self-regulated interstellar medium. The same galaxy is simulated twice: once with self-consistent stellar spiral arms and once more with the stellar spirals suppressed via a novel numerical approach, using the Ramses adaptive mesh refinement code. Spiral arms continually promote star formation, with 2.6 times higher rates in the spiral galaxy. The higher rate is due to high gas columns gathered along the spiral arms, rather than increasing the star formation efficiency at a given gas column. In both cases, the magnetic field is initially amplified via a small-scale dynamo driven by turbulence due to supernova feedback. Only the spiral galaxy exhibits late-time, consistent field growth due to a large-scale dynamo ( e -folding time ∼600 Myr). This results in volume-averaged field strengths of ∼1 μ G after 1 Gyr of evolution. The mean fields tend to align themselves with the spiral arms and are coherent up to 10 kpc scales. We demonstrate a novel large-scale dynamo mechanism, whereby spiral-driven radial flows enable the mean-field amplification.}, archive = {J_ApJ}, author = {Hector Robinson and James Wadsley and J. A. Sellwood and Ralph E. Pudritz}, doi = {10.3847/1538-4357/ade9c1}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {205}, shortjournal = {The Astrophys. J.}, title = {Star formation and magnetic field amplification due to galactic spirals}, volume = {989}, year = {2025}, }
• (2025). Photospheric helium abundance in cool giants: A comprehensive study. ApJ, 989(2), 204. (www)

  @article{ , abstract = {High-resolution optical spectra of 16 red giants, two early asymptotic giant branch (AGB) stars, and two supergiants, having no/minimal - to super-lithium (Li)-rich abundances, are analyzed to investigate the helium (He)-enhancement. The spectra of eight giants were obtained from the Himalayan Chandra Telescope, and for the rest of the program stars the spectral data were collected from various public archives. Our detailed abundance analyses of the program stars involve the determination of stellar parameters and abundances for about 20 elements among the key abundances of He, Li, C, N, O, and the 12 C/ 13 C ratios. The difference in the Mg abundance derived from Mg i lines and the MgH band, and the difference in carbon abundance from C i and the CH band, are used as a clue to the mild hydrogen-deficiency/helium-enhancement. From this analysis, four red giants, an early-AGB star, and a supergiant star were found to be enhanced in helium. All these He-enhanced stars are also found to be super-Li rich except for the supergiant. Since the He-rich red giants are Li rich as well, this implies that He enrichment is accompanied by Li enrichment, but not vice versa. This is the first spectroscopic measurement of photospheric He abundance in normal and Li-rich field giants. The Li enrichment is observed across the giant branch from red giant branch (RGB)-bump (KIC 9821622) to AGB phase, unlike that expected from the RGB-tip to red clump phase. A plausible scenario for the enrichment of He as well as Li in giants is the fresh synthesis of Li in the interiors of giants and dredging-up along with He to the surface from deeper layers. However, there could be multiple scenarios operating in tandem. This analysis of He and Li enrichment along with other key elements provides more insights to decipher the mystery of Li enrichment in giants.}, archive = {J_ApJ}, author = {B. P. Hema and Gajendra Pandey}, doi = {10.3847/1538-4357/adea40}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {204}, shortjournal = {The Astrophys. J.}, title = {Photospheric helium abundance in cool giants: A comprehensive study}, volume = {989}, year = {2025}, }
• (2025). Dialog concerning the two shock codes. ApJ, 989(2), 203. (www)

  @article{ , abstract = {In this paper, we summarize the shock physics and the treatment of radiative transfer in two well-established shock codes—the MAPPINGS code and the Cox/Raymond code. We compare the ionization states, temperatures, electron densities, and energy transportations of the shock models with shock velocities of 50, 110, 150, and 300 km s −1 . In summary, both codes adopt the Rankine–Hugoniot flow equation to describe the shock flows, giving the same shock physical properties in the immediate area behind the shock fronts. The different treatments of radiative transfer in these two codes lead to somewhat different computations of the ionization and thermal structures of shocks, as well as the emission-line fluxes. This work highlights the importance of the delicate treatment of photoionization in shock models, providing insight for the future development of shock codes, such as 3D shock codes.}, archive = {J_ApJ}, author = {Yifei Jin and John Raymond}, doi = {10.3847/1538-4357/adeca2}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {203}, shortjournal = {The Astrophys. J.}, title = {Dialog concerning the two shock codes}, volume = {989}, year = {2025}, }
• (2025). A NuSTAR study of quasiperiodic oscillations from the ultraluminous X-ray sources in m82. ApJ, 989(2), 202. (www)

  @article{ , abstract = {The study of quasiperiodic oscillations (QPOs) in X-ray binaries provides valuable insights into the physics of accretion around compact objects. The M82 galaxy hosts multiple ultraluminous X-ray sources, including two prominent ones—X-1 and X-2—where X-1 is suspected to harbor an intermediate-mass black hole. In this work, we analyze data from 39 NuSTAR observations acquired between 2014 and 2024 to investigate the aperiodic X-ray variability in M82. In particular, we study in detail the evolution of the QPOs from M82 X-1 in the range 20–300 mHz. We do not find additional timing features in the data, besides a frequently present broad noise component at lower frequencies. The QPO behaves similarly to other classes of low-frequency oscillations in accreting compact objects, both black holes and neutron stars.}, archive = {J_ApJ}, author = {Hamza El Byad and Matteo Bachetti and Silvia Columbu and Giuseppe Rodriguez and Maura Pilia and Matthew J. Middleton and Dominic J. Walton and Murray Brightman and Hannah Earnshaw and Karl Forster and Brian Grefenstette and Felix Fürst and Marianne Heida and Matteo Imbrogno and Eleonora Veronica Lai and Thomas Maccarone}, doi = {10.3847/1538-4357/aded8a}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {202}, shortjournal = {The Astrophys. J.}, title = {A NuSTAR study of quasiperiodic oscillations from the ultraluminous X-ray sources in m82}, volume = {989}, year = {2025}, }
• (2025). Enabling robust exoplanet atmospheric retrievals with gaussian processes. ApJ, 989(2), 201. (www)

  @article{ , abstract = {Atmospheric retrievals are essential tools for interpreting exoplanet transmission and eclipse spectra, enabling quantitative constraints on the chemical composition, aerosol properties, and thermal structure of planetary atmospheres. The James Webb Space Telescope (JWST) offers unprecedented spectral precision, resolution, and wavelength coverage, unlocking transformative insights into the formation, evolution, climate, and potential habitability of planetary systems. However, this opportunity is accompanied by challenges: modeling assumptions and unaccounted-for noise or signal sources can bias retrieval outcomes and their interpretation. To address these limitations, we introduce a Gaussian process (GP)-aided atmospheric retrieval framework that flexibly accounts for unmodeled features and correlated noise in exoplanet spectra. We validate this method on synthetic JWST observations, and show that GP-aided retrievals reduce bias in inferred abundances and better capture model–data mismatches than traditional approaches. We also introduce the concept of mean squared error to quantify the trade-off between bias and variance, arguing that this metric more accurately reflects retrieval performance than bias alone. We then reanalyze the NIRISS/SOSS JWST transmission spectrum of WASP-96 b, finding that GP-aided retrievals yield broader constraints on CO 2 and H 2 O, possibly alleviating tension between previous retrieval results and equilibrium predictions. Our GP framework provides precise and accurate constraints while highlighting regions where models fail to explain the data. As JWST matures and future facilities come online, a deeper understanding of the limitations of both data and models will be essential, and GP-enabled retrievals like the one presented here offer a principled path forward.}, archive = {J_ApJ}, author = {Yoav Rotman and Luis Welbanks and Michael R. Line and Peter McGill and Michael Radica and Matthew C. Nixon}, doi = {10.3847/1538-4357/adef04}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {201}, shortjournal = {The Astrophys. J.}, title = {Enabling robust exoplanet atmospheric retrievals with gaussian processes}, volume = {989}, year = {2025}, }
• (2025). Observations of microwave emission from solar jets and comparison with magnetohydrodynamic simulations. ApJ, 989(2), 200. (www)

  @article{ , abstract = {We computed the thermal microwave emission from a 3D magnetohydrodynamic (MHD) simulation and compared it with observations of solar jets. The simulation treats the emergence of magnetic flux into the solar atmosphere and its interaction with a low, preexisting ambient magnetic field. This interaction leads to the formation and development of a jet, driven by an eruption. The computed 17 GHz radio emission is compared with a number of observed jets, with respect to their morphology, their flux, and the rise time of the radio flux. We find that the MHD model reproduces the characteristics of lower-intensity jets reasonably well, whereas there are differences with stronger jets. We suggest possible ways to obtain more realistic jets from MHD simulations, so that they better match the real jets.}, archive = {J_ApJ}, author = {Costas E. Alissandrakis and Vasilis Archontis and Kostas Moraitis}, doi = {10.3847/1538-4357/adf060}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {200}, shortjournal = {The Astrophys. J.}, title = {Observations of microwave emission from solar jets and comparison with magnetohydrodynamic simulations}, volume = {989}, year = {2025}, }
• (2025). X-ray measurements of 44Ti in four supernova remnants. ApJ, 989(2), 199. (www)

  @article{ , abstract = {We present the results of a search for scandium K α X-ray fluorescence resulting from 44 Ti electron capture decay in four young supernova remnants (SNRs). We analyze archival XMM-Newton data from Tycho’s SNR, Kepler’s SNR, Cassiopeia A, and SN 1987A. We fit the X-ray spectra in regions of interest with up to four components, thermal and power-law, as needed to fit the spectrum, and add a Gaussian to test for extra Sc emission. While all require the line with modest confidence, none represent definitive detections on their own, and all are consistent with previous gamma-ray detections or limits on the 44 Ti mass.}, archive = {J_ApJ}, author = {Tyler E. Hanover and Mark D. Leising}, doi = {10.3847/1538-4357/adec8b}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {199}, shortjournal = {The Astrophys. J.}, title = {X-ray measurements of 44Ti in four supernova remnants}, volume = {989}, year = {2025}, }
• (2025). Evolution of crab pulsar: Magnetic inclination angle and spin. ApJ, 989(2), 198. (www)

  @article{ , abstract = {The well-observed Crab pulsar helps one to uncover the underlying knowledge about pulsar evolution. The routine evolution model simultaneously describes the spin-down caused by magnetic dipole radiation and gravitational-wave radiation (GWR), the damping of the free-body precession owing to the bulk viscosity, and the GWR-induced quenching of the magnetic inclination angle χ . We explore the pulsar evolution based on this routine model supplemented with the effects of shear viscosity, r -mode, electromagnetic torque, and accretion, with the stellar thermal evolution as an important input. The impact of shear viscosity on radio pulsar evolution is negligible, as it only slightly increases the magnetic inclination angle and promotes spin-down in magnetars. Under the observational limit for its saturation amplitude, the r -mode also turns out to be completely negligible. Yet, the electromagnetic torque (under certain conditions), along with the accretion based on our three-dimensional fallback disk accretion model, is shown to suppress the growth of the magnetic inclination angle. When applied to the Crab pulsar, the routine model best reproduces the magnetic inclination angle χ , the spin period P , and the spin period derivative \dot{P} simultaneously, indicating the important role of bulk viscosity. The inclusion of the electromagnetic torque and accretion works even worse, suggesting these two factors perhaps are overestimated for the Crab pulsar. Intriguingly, the calculated magnetic inclination angle derivative \dot{\chi } is (6 \mathop{.}\limits^{{\rm{^\circ }}} 3 × 10 −3 –0 \mathop{.}\limits^{\unicode{x000b0}} 3) century –1 with the routine model, also in agreement with the observed tiny \dot{\chi }=0\mathop{.}\limits^{\unicode{x000b0}}62\,{\mathrm{century}}^{\mbox{--}1} .}, archive = {J_ApJ}, author = {Cong-Xing Liu and Jian-Min Dong}, doi = {10.3847/1538-4357/adef3e}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {198}, shortjournal = {The Astrophys. J.}, title = {Evolution of crab pulsar: Magnetic inclination angle and spin}, volume = {989}, year = {2025}, }
• (2025). How a Klein–Nishina modified eddington-limited accretion explains rapid black hole growth in the early universe. ApJ, 989(2), 197. (www)

  @article{ , abstract = {The discovery of quasars and their supermassive black holes (SMBHs) over 10 9 {M}_{{\rm{\odot }}} merely hundreds of millions of years after the Big Bang generates tension with the idea of Eddington-limited accretion and pressures the community into exploring the concept of massive black hole seeds and/or super-Eddington accretion. The observation that many black holes have reached supermassive status while obeying the Eddington limit is puzzling, as accretion models are not spherically symmetric. We address this issue by illustrating the physics behind a picture of inner disk accretion involving a geometrically thick, hot quasi-spherical flow, and argue that such an inner region provides the radiation that instantiates the Eddington limit. Given the energetics of the inner disk edge, we show how the characteristic electron cross section drops below its Thomson value, allowing black holes to grow rapidly despite being Eddington-limited. Indeed, after implementing a modified cross section calculated via the Klein–Nishina formula, we find that SMBH formation time drops by up to 47%. In this context, we show how a 10 9 {M}_{{\rm{\odot }}} black hole can form from a seed 10 {M}_{{\rm{\odot }}} black hole within 500 Myr by way of accretion and mergers. While our picture is oversimplified and contrived in a number of ways that we discuss, we suggest that our scenario is interesting in that it offers a solution to two issues at the intersection of astrophysics and cosmology, namely the reason the Eddington limit is obeyed and how some black holes have grown rapidly despite that limit.}, archive = {J_ApJ}, author = {Jackson Frangos and Erick Rosen and Michael Williams and Chandra B. Singh and David Garofalo}, doi = {10.3847/1538-4357/adf05c}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {197}, shortjournal = {The Astrophys. J.}, title = {How a Klein–Nishina modified eddington-limited accretion explains rapid black hole growth in the early universe}, volume = {989}, year = {2025}, }
• (2025). Disk instability model for quasi-periodic eruptions: Investigating period dispersion and peak temperature. ApJ, 989(2), 196. (www)

  @article{ , abstract = {Quasi-periodic eruptions (QPEs) are a class of X-ray repeating burst phenomena discovered in recent years. Although many models have been proposed to study this phenomenon, there remains significant debate regarding the physical origin of QPEs. In our previous work, we developed a disk instability model with a large-scale magnetic field and successfully reproduced the light curves and spectral characteristics of several QPE sources. We further investigate this model in this work, aiming to explain two key observational features: the dispersion in eruption periods and the peak temperatures during eruptions. This model reveals critical thresholds ( {\dot{M}}_{{\rm{crit}}} , β 1,crit ) that separate systems into stable regimes with minimal period variations and unstable regimes where periods are highly sensitive to the accretion rate and magnetic field parameter, while peak temperatures remain nearly constant across the parameter space. This framework successfully explains both the regular eruptions observed in sources such as GSN 069 and the stochastic behavior in sources such eRO-QPE1, while simultaneously accounting for the observed temperature stability during long-term evolution of QPEs.}, archive = {J_ApJ}, author = {Xin Pan and Shuang-Liang Li and Xinwu Cao and Bifang Liu and Weimin Yuan}, doi = {10.3847/1538-4357/adf05d}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {196}, shortjournal = {The Astrophys. J.}, title = {Disk instability model for quasi-periodic eruptions: Investigating period dispersion and peak temperature}, volume = {989}, year = {2025}, }
• (2025). Weak X-ray bursts on slowly accreting neutron stars. ApJ, 989(2), 195. (www)

  @article{ , abstract = {Nearly all observed thermonuclear X-ray bursts are thought to be triggered by the thermally unstable triple-alpha process. Unlike in accreting white dwarfs, the ≳10 8 K envelope temperature forces hydrogen burning to proceed via the β -limited, thermally stable hot CNO cycle. Recent observations of weak X-ray bursts from SAX J1808.4–3658 occurring within 1–3 days of the onset of an accretion outburst have raised the question that these bursts were triggered by thermally unstable hydrogen ignition, analogously to classical novae. Using the stellar evolution code MESA , we explore the unstable ignition of hydrogen on slowly accreting neutron stars. For solar metallicities, the burning is insufficiently vigorous to launch convection and the burst rise is on the envelope thermal timescale, with the hydrogen being consumed over hours. For elevated metallicities ( Z ≳ 0.06), however, the initial proton captures onto CNO nuclei heat the envelope enough to drive convection and produce a sharp peak in the luminosity. This peak can match that of the SAX J1808.4–3658 burst for sufficient enrichment. Following this peak, the hydrogen burning stabilizes at a rate set solely by the ignition depth and CNO abundance in the accreted matter. This quasi-steady-state burning produces an extended tail of elevated emission that lasts until the hydrogen is exhausted. Observations of the tail’s luminosity and duration measure the hydrogen and metallicity abundance of the accreted material, while the distance-independent ratio of peak-to-tail luminosities would suggest the presence of significant metallicity gradients prior to convection.}, archive = {J_ApJ}, author = {Sierra Casten and Simon Guichandut and Andrew Cumming and Edward F. Brown}, doi = {10.3847/1538-4357/adf106}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {195}, shortjournal = {The Astrophys. J.}, title = {Weak X-ray bursts on slowly accreting neutron stars}, volume = {989}, year = {2025}, }
• (2025). Where is the supervirial gas? III. insights from X-ray shadow observations and a revised model for the soft diffuse X-ray background. ApJ, 989(2), 194. (www)

  @article{ , abstract = {Shadow observations provide a powerful tool to separate foreground components of the soft diffuse X-ray background (SDXB) from the background components. Such observations have now established that the “local” foreground is made of the solar wind charge exchange and the Local Bubble, and the background emission is from the extended circumgalactic medium (CGM) of the Milky Way and from the unresolved extragalactic sources. New data and careful analyses of the SDXB led to two new discoveries in recent years: (1) excess emission near 0.5 keV that is identified as the N vii emission line, and (2) excess emission near 0.8−1.0 keV that is identified with an additional, supervirial temperature hot thermal component of the CGM. The goal of this paper is to use Suzaku shadow observations along six sightlines to determine whether either of these components is from the “local” sources. We eliminate the ambiguity regarding the origin of N vii emission, ruling out the local origin. We confirm that the Milky Way CGM contains nitrogen-rich plasma, with a supersolar average (N/O) of 2.6 ± 0.5, and suggest that nitrogen-enhanced plasma is widespread throughout the CGM. We find supersolar Ne abundance in two sightlines, also from the CGM. Similarly, we rule out the local origin of the hot thermal component and confirm that it is present beyond the shadowing clouds. Furthermore, we provide a revised model of the SDXB, which is crucial for extragalactic astronomy.}, archive = {J_ApJ}, author = {Anjali Gupta and Smita Mathur and Joshua Kingsbury and Esma Korkmaz and Sanskriti Das and Yair Krongold and Manami Roy and Armando Lara-DI}, doi = {10.3847/1538-4357/adf10b}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {194}, shortjournal = {The Astrophys. J.}, title = {Where is the supervirial gas? III. insights from X-ray shadow observations and a revised model for the soft diffuse X-ray background}, volume = {989}, year = {2025}, }
• (2025). Detection of transitions between dwarf nova outbursts, standstills, and IW and–type cycles. ApJ, 989(2), 193. (www)

  @article{ , abstract = {IW And–type objects represent a rare and intriguing subclass of cataclysmic variables that challenge the classical disk instability model. Due to their long timescales, often lasting several months, observed samples are scarce, leaving the physics of state transitions poorly understood. Here, we report the discovery of ASASSN-V J175721.00+152502.1 as a new IW And–type system based on both ground-based and space-based survey data. For the first time, we measure its orbital period and negative superhump (NSH) period as 0.25619(81) days and 0.24107(33) days, respectively. We present detailed observational evidence for transitions between IW And–type cycles, classical standstills, and normal dwarf nova outbursts. Notably, the transition from the IW And–type cycle to a classical standstill is presented in detail for the first time, together with a decrease in the NSH period, which provides evidence for accretion disk expansion. We evaluate theoretical models that could explain the observed light variations and rule out simple scenarios such as mass-transfer bursts or superoutbursts. Although the tilted-disk thermal instability model is the most plausible, it does not fully account for the detailed behavior. We propose that a combination of factors, such as thermal-viscous instabilities, fluctuations in the mass-transfer rate, changes in the disk radius, tilted disk precession, and tidal dissipation involving the secondary star, is likely needed to explain the full range of observed phenomena.}, archive = {J_ApJ}, author = {Qi-Bin Sun and Sheng-Bang Qian and Li-Ying Zhu and Qin-Mei Li and Wen-Ping Liao and Fu-Xing Li and Wen-Xu Lin and Min-Yu Li and Ping Li}, doi = {10.3847/1538-4357/adf4e9}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {193}, shortjournal = {The Astrophys. J.}, title = {Detection of transitions between dwarf nova outbursts, standstills, and IW and–type cycles}, volume = {989}, year = {2025}, }
• (2025). Peaky finders: Characterizing double-peaked type IIb supernovae in large-scale live-stream photometric surveys. ApJ, 989(2), 192. (www)

  @article{ , abstract = {We present the first photometric population study of double-peaked Type IIb supernovae (SNe IIb). SNe IIb are produced from the core collapse of massive stars whose outermost hydrogen layer has been partially stripped prior to explosion. These double-peaked light curves, consisting of a shock-cooling emission (SCE) peak followed by the main nickel-powered peak, contain more crucial information about the progenitor system than the typical single-peaked light curves. We compiled and analyzed a sample of 14 spectroscopically confirmed SNe IIb—including previously unpublished and reclassified—with publicly available photometric observations, discovered between 2018 and 2022, from the Zwicky Transient Facility and Asteroid Terrestrial-impact Last Alert System surveys. We developed and fit a piecewise linear model, referred to as the “lightning bolt” model, to describe the early-time behavior of these objects to measure population statistics. Notably, we find the SCE peak lasts, on average, fewer than 5 days above half-maximum light, with a mean rise time of 2.07  ±  1.0 and 1.1  ±  0.8 mag day −1 in the g and r bands, respectively. These SCE rise rates are over 10× faster than—and last only a third the duration of—the rise to the Ni-powered peak. These rise times are comparable to those of fast blue optical transient events, and we discuss the implications in the text. Finally, we present a proof-of-concept alert filter, using the ANTARES broker, to demonstrate how to translate these population statistics into simple and effective filters to find potential double-peaked SNe IIb in large-scale survey alert streams, like the imminent Vera C. Rubin Observatory Legacy Survey of Space and Time.}, archive = {J_ApJ}, author = {Adrian Crawford and Tyler A. Pritchard and Maryam Modjaz and Craig Pellegrino and Sahana Kumar and Raphael Baer-Way}, doi = {10.3847/1538-4357/adea3a}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {192}, shortjournal = {The Astrophys. J.}, title = {Peaky finders: Characterizing double-peaked type IIb supernovae in large-scale live-stream photometric surveys}, volume = {989}, year = {2025}, }
• (2025). On the origin of the short-lived cocoon in 3C 84: Powered by tidal disruption events?. ApJ, 989(2), 191. (www)

  @article{ , abstract = {We evaluated the jet power and the density of ambient matter in 3C 84 by using the momentum balance along the jet axis and the transonic condition for the cocoons observed at two different scales (approximately 1 and 6 pc). For the inner cocoon, we precisely determined the ratio of jet power to ambient density L j / n a to be (0.3–0.7) × 10 43 erg s −1 cm 3 . Similarly, for the outer cocoon, we found that this value is more than an order of magnitude larger at (0.9–3.7) × 10 44 erg s −1 cm 3 . This indicates that the outer cocoon is formed by a powerful jet that propagates through an ambient density of 20–300 cm −3 with a jet power of 10 45−46.5 erg s −1 . On the other hand, the inner cocoon is formed by a weaker jet with a power of 10 43−44 erg s −1 , propagating through a relatively low-density environment of 6–20 cm −3 . These results suggest that (1) with respect to the difference in n a , it appears to support the hypothesis that the inner cocoon, recently formed about 10 yr ago, is expanding in the low-density environment created by the jet emitted about 25–50 yr ago; (2) to achieve the short-lived and high L j that generated the outer cocoon, a large mass-accretion rate is required over a short period to activate the jet. These may imply an extreme accretion event driven by the tidal disruption events of massive stars and/or the disk instability.}, archive = {J_ApJ}, author = {Nozomu Kawakatu and Motoki Kino and Keiichi Wada}, doi = {10.3847/1538-4357/adea6d}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {191}, shortjournal = {The Astrophys. J.}, title = {On the origin of the short-lived cocoon in 3C 84: Powered by tidal disruption events?}, volume = {989}, year = {2025}, }
• (2025). X-ray reflection signatures of supermassive black hole binaries. ApJ, 989(2), 190. (www)

  @article{ , abstract = {We investigate the presence of supermassive black hole (SMBH) binary signatures and the feasibility of identifying them through X-ray reflection spectra. The X-ray emitting region is modeled as a set of two mini-disks bound to the individual SMBHs separated by 100 GM / c 2 and the spectra calculated as a function of the mass, mass ratio, and total accretion rate of the binary. The X-ray reflection features are strongly influenced by the accretion-inversion phenomenon expected in SMBH binaries, which results in a wide range of ionization conditions in the two mini-disks. These are imprinted in the resulting composite spectra and the double-peaked and time-variable relativistic Fe K α line profiles. To test whether these features can be used as evidence for the presence of an SMBH binary, we fit mock 100 ks observations with a single active galactic nucleus (AGN) model. For a 10 9 M ⊙ binary targeted by pulsar timing arrays (PTAs), at z = 0.1, the single AGN model clearly fails to fit the data, while at z = 1, the fit is acceptable but unable to converge on the SMBH spin. For a 10 6 M ⊙ binary, a progenitor of a Laser Interferometer Space Antenna (LISA) source, spectral fitting is only possible at z = 0.1, with the outcomes similar to the PTA binary at z = 1. We also find that PTA binaries can be expected to show a distinct X-ray spectral variability in multiepoch observations, whereas for LISA precursors, orbital averaging results in the loss of spectral variability signatures.}, archive = {J_ApJ}, author = {Julie Malewicz and David R. Ballantyne and Tamara Bogdanović and Laura Brenneman and Thomas Dauser}, doi = {10.3847/1538-4357/adea75}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {190}, shortjournal = {The Astrophys. J.}, title = {X-ray reflection signatures of supermassive black hole binaries}, volume = {989}, year = {2025}, }
• (2025). Precise asteroseismic ages for the helmi streams. ApJ, 989(2), 189. (www)

  @article{ , abstract = {The Helmi streams are remnants of a dwarf galaxy that was accreted by the Milky Way and whose stars now form a distinct kinematic and chemical substructure in the Galactic halo. Precisely age-dating these typically faint stars of extragalactic origin has been notoriously difficult due to the limitations of using only spectroscopic data, interferometry, or coarse asteroseismic measurements. Using observations from NASA’s Transiting Exoplanet Survey Satellite, we report detailed asteroseismic modeling results for two of the brightest red giants within the Helmi streams, HD 175305 and HD 128279. By modeling the individual oscillation mode frequencies and the spectroscopic properties of both stars, we determine their fundamental properties including mass, radius, and age ( τ ). We report τ = 11.16 ± 0.91 Gyr for HD 175305 and τ = 12.52 ± 1.05 Gyr for HD 128279, consistent with previously inferred star formation histories for the Helmi streams and the differential chemical abundances between the two stars. With precise ages for individual stream members, our results reinforce the hypothesis that the Helmi streams’ progenitor must have existed at least 12 Gyr ago. Our results also highlight that the ages of metal-poor, α -enhanced red giants can be severely underestimated when inferred using global asteroseismic parameters instead of individual mode frequencies.}, archive = {J_ApJ}, author = {Christopher J. Lindsay and Marc Hon and J. M. Joel Ong and Rafael A. García and Dinil B. Palakkatharappil and Jie Yu and Tanda Li and Tomás Ruiz-Lara and Amina Helmi}, doi = {10.3847/1538-4357/adeb56}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {189}, shortjournal = {The Astrophys. J.}, title = {Precise asteroseismic ages for the helmi streams}, volume = {989}, year = {2025}, }
• (2025). Mass-gap black holes in coalescing neutron Star–Black hole binaries. ApJ, 989(2), 188. (www)

  @article{ , abstract = {The existence of a mass gap of 3–5 M ⊙ between the heaviest neutron stars (NSs) and the lightest black holes (BHs), inferred from the BH mass distribution in low-mass X-ray binaries (LMXBs), has been suggested for decades. The gravitational-wave (GW) source GW230529 is most likely a neutron star–black hole (NSBH) merger, with the BH mass falling within this gap. This detection strongly challenges the existence of the gap and has implications for the NSBH population, including a revised BH mass distribution and an updated local merger rate. In this study, we employ POSYDON , a binary population synthesis code that integrates detailed single- and binary-star models, to investigate coalescing NSBH binaries, focusing on the BH mass distribution of the intrinsic NSBH merger population. For typical population models, we find that better matching the observed BH mass distribution requires the use of common-envelope (CE) efficiencies exceeding unity, a rather uncomfortable choice since most energy sources are already included. Alternatively, we find that a two-stage CE prescription calibrated to 1D hydrodynamic simulations has a similar effect. Moreover, motivated by a possible explanation for the firm presence of the mass gap in the LMXB sample, we examine models where the NS birth mass is limited to ≲2 M ⊙ and find excellent agreement with GW observations. Additionally, we present observable distributions of NSBH merger properties, finding good agreement with the measured properties of observed systems and a predicted fraction of NSBH mergers with potential electromagnetic counterparts that ranges from 1% all the way up to 32%.}, archive = {J_ApJ}, author = {Zepei Xing and Vicky Kalogera and Tassos Fragos and Jeff J. Andrews and Simone S. Bavera and Max Briel and Seth Gossage and Konstantinos Kovlakas and Matthias U. Kruckow and Kyle Akira Rocha and Meng Sun and Philipp M. Srivastava and Emmanouil Zapartas}, doi = {10.3847/1538-4357/adec6d}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {188}, shortjournal = {The Astrophys. J.}, title = {Mass-gap black holes in coalescing neutron Star–Black hole binaries}, volume = {989}, year = {2025}, }
• (2025). On the width and profiles of cosmic filaments. ApJ, 989(2), 187. (www)

  @article{ , abstract = {We investigated the widths and profiles of cosmic filaments using the IllustrisTNG simulations. Filaments were identified with DisPerSE , using galaxy samples in simulations as input. Since the width of an individual filament can vary significantly along its spine, we divided each filament into segments with lengths between 1.5 and 2.5 h −1 Mpc and measure their properties. The typical width of these filament segments increases gradually from approximately 0.3 Mpc at redshift z = 2 to about 1.0–1.5 Mpc at z = 0. We find that the segment width correlates nearly linearly with the linear halo mass density, consistent with previous studies. A similar linear relation is observed between the segment width and the linear stellar mass density, providing a potential estimator for filament width. Furthermore, the density profiles of filaments with different widths exhibit self-similarity and can be described by a unified formula akin to the isothermal β model. For segments with a given width, the rescaled density profiles show only mild evolution from z = 2 to z = 0. Within the filament width, the gas temperature decreases slowly from the center to the boundary, with thicker filaments generally containing hotter gas than thinner ones. These trends in filament width, density, and thermal profiles are consistently observed across the TNG50, TNG100, and TNG300 simulations, and align well with results from earlier studies. We briefly discuss the potential implications and applications of our findings.}, archive = {J_ApJ}, author = {Qi-Rui Yang and Weishan Zhu and Guang-Yao Yu and Jian-Feng Mo and Yi Zheng and Long-Long Feng}, doi = {10.3847/1538-4357/adeca3}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {187}, shortjournal = {The Astrophys. J.}, title = {On the width and profiles of cosmic filaments}, volume = {989}, year = {2025}, }
• (2025). A radio flaring, chromospherically inactive k dwarf. ApJ, 989(2), 186. (www)

  @article{ , abstract = {We report on an unusual radio source (J180526−292953), initially identified as a steep spectrum, polarized point source toward the Galactic bulge and found to coincide with the nearby K dwarf HD 317101A. We conducted a multiwavelength radio study utilizing new GMRT observations and archival data from ASKAP, MeerKAT, and the Very Large Array. At 1.5 GHz, HD 317101A exhibits highly polarized coherent emission with variable activity lasting several hours with an apparent period of 3.7 days, which is consistent with electron cyclotron maser (ECM) emission. The behavior at 3 GHz is distinctive, with a short burst lasting tens of seconds to minutes, a flat spectrum, and no detected polarization, possibly suggesting gyro-synchrotron emission. High-resolution optical spectroscopy from CHIRON/SMARTS confirms HD 317101A as a mature, chromospherically inactive K7V star, while Gaia astrometry, combined with speckle imaging from Zorro/Gemini-S, indicates the presence of a close-in M5.5V companion. We evaluated three possible origins for the combined radio behavior: chromospheric activity, auroral emission (possibly from a star–planet interaction), or an ultralong-period transient. The bulk of the evidence favors an auroral origin, but the dominant stellar source of the ECM emission remains uncertain. Future very-long baseline interferometry observations, long-term TESS monitoring, high-resolution spectroscopy, and further radio characterization will be key to distinguishing between various scenarios.}, archive = {J_ApJ}, author = {Dale A. Frail and Scott D. Hyman and Michele L. Silverstein and Emil Polisensky and Evangelia Tremou and Simona Giacintucci and Hodari-Sadiki Hubbard-James and Jacinda Byam and Steve B. Howell and Robert F. Wilson and Matthew Lastovka and Tracy E. Clarke and Namir E. Kassim}, doi = {10.3847/1538-4357/adee14}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {186}, shortjournal = {The Astrophys. J.}, title = {A radio flaring, chromospherically inactive k dwarf}, volume = {989}, year = {2025}, }
• (2025). Modeling the impacts of galaxy intrinsic alignments on weak lensing peak statistics. ApJ, 989(2), 185. (www)

  @article{ , abstract = {Weak gravitational lensing (WL) peak statistics capture cosmic nonlinear structures and can provide additional cosmological information complementary to cosmic shear two-point correlation analyses. They have been applied to different WL surveys successfully. To further facilitate their high-precision applications, it is very timely to investigate the impacts of different systematics on WL peak statistics and how to mitigate them. Concerning the influence of galaxy intrinsic alignments (IAs), in this paper, we develop a theoretical model for WL high peaks taking into account the IA effects. It is an extension of our previous halo-based model. The IA corrections mainly include the modification of the lensing profile of clusters of galaxies due to the alignments of satellite galaxies and the additional shape noise correlations. We validate our model using simulations with the semi-analytical galaxy formation. We consider the cases where the satellite galaxies are on average radially aligned toward the centers of their host clusters but with different dispersions σ θ . We show that our model works well for σ θ > 45°. If the IA corrections are not included in the model, for the Euclid/CSST–like source galaxy distribution and the survey area of ∼1000 deg 2 , the IA-induced bias on S 8 can reach ∼8 σ even for σ θ = 75°. With our model, not only can the bias be well mitigated, but we can also constrain the satellite IA to the level of σ ( σ θ ) ∼ ±24° simultaneously from WL high peak analyses alone using data from such a survey.}, archive = {J_ApJ}, author = {Tianyu Zhang and Xiangkun Liu and Ziwei Li and Chengliang Wei and Guoliang Li and Yu Luo and Xi Kang and Zuhui Fan}, doi = {10.3847/1538-4357/adef41}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {185}, shortjournal = {The Astrophys. J.}, title = {Modeling the impacts of galaxy intrinsic alignments on weak lensing peak statistics}, volume = {989}, year = {2025}, }
• (2025). Inclination effect on observational identification of outflow rotation in magnetohydrodynamics simulations. ApJ, 989(2), 184. (www)

  @article{ , abstract = {We investigate the observational signatures of outflow rotation in protostellar systems using magnetohydrodynamics simulations of protostellar evolution with radiative transfer and synthetic observation. The velocity gradient perpendicular to the outflow axis indicates outflow rotation. The rotation signature is clearly seen in the moment 1 map and a position–velocity (PV) diagram across an outflow lobe made from our model with an inclination angle of i ≳ 85°, as in observational studies of protostellar outflows. Velocity projection with lower inclinations distorts the moment 1 map because the outflow vertical (propagation) velocity contributes more to the line-of-sight velocity, leading to an incorrect outflow axis direction. The PV diagram adopting the incorrect outflow axis shows no clear velocity gradient. These effects may prevent us from identifying outflow rotation. Our analysis implies that rotational signatures can be obscured in ∼2/3 to ∼4/5 of the total outflow population ( i < 70°–80°), regardless of the evolutionary stage. Complicated structures in observed outflows make it difficult to determine the outflow axis, which may result in the apparent nondetection of outflow rotation.}, archive = {J_ApJ}, author = {Yusuke Aso and Masahiro N. Machida}, doi = {10.3847/1538-4357/adf18f}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {184}, shortjournal = {The Astrophys. J.}, title = {Inclination effect on observational identification of outflow rotation in magnetohydrodynamics simulations}, volume = {989}, year = {2025}, }
• (2025). Multiline spectropolarimetric observation of flare ribbon fine structures with ViSP/DKIST. ApJ, 989(2), 183. (www)

  @article{ , abstract = {We present an analysis of flare ribbon fine structure observed during a GOES C2-class flare using high spatial and spectral resolution multiline spectropolarimetric observations from the ViSP instrument at the DKIST. The ViSP recorded full Stokes spectra in three lines: Fe i 6301 Å line pair, Na i D1, and Ca ii 8542 Å. To infer the stratification of temperature and line-of-sight (LOS) velocity across the ribbon, we performed non–local thermodynamic equilibrium multiline inversions of ViSP spectra. In the red wing of the Ca ii line, we identified multiple compact, roundish, and quasi-equally spaced bright structures, referred to as ribbon blobs, embedded within the flare ribbon. The sizes of these blobs range from 320 to 455 km, and they are spaced roughly ∼1100 km apart. These features exhibit complex spectral profiles with pronounced asymmetries and double peaks near the line core of the Ca ii 8542 line. The blob regions were found to be significantly hotter (by ∼1 kK) at {\mathrm{log}}\,{\tau }_{500}=-4 compared to surrounding ribbon areas (∼7 kK). The LOS velocity maps revealed both upflows and downflows at {\mathrm{log}}\,{\tau }_{500}=-4 and {\mathrm{log}}\,{\tau }_{500}=-3 , respectively. We discuss the plausible origins of these fine structures in the chromosphere, which may be related to electron beam heating, plasma draining, or tearing-mode instabilities in the reconnecting current sheet.}, archive = {J_ApJ}, author = {Rahul Yadav and Maria D. Kazachenko and Gianna Cauzzi and Cole A. Tamburri and Marcel Corchado and Ryan French}, doi = {10.3847/1538-4357/adf4c1}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {183}, shortjournal = {The Astrophys. J.}, title = {Multiline spectropolarimetric observation of flare ribbon fine structures with ViSP/DKIST}, volume = {989}, year = {2025}, }
• (2025). Evidence for an instability-induced binary merger in the double-peaked, helium-rich type IIn supernova 2023zkd. ApJ, 989(2), 182. (www)

  @article{ , abstract = {We present ultraviolet to infrared observations of the extraordinary Type IIn supernova 2023zkd (SN 2023zkd). Photometrically, it exhibits persistent and luminous precursor emission spanning ∼4 yr preceding discovery ( M r ≈ −15 mag, 1500 days in the observer frame), followed by a secondary stage of gradual brightening in its final year. Post-discovery, it exhibits two photometric peaks of comparable brightness ( M r ≲ −18.7 mag and M r ≈ −18.4 mag, respectively) separated by 240 days. Spectroscopically, SN 2023zkd exhibits highly asymmetric and multicomponent Balmer and He I profiles that we attribute to ejecta interaction with fast-moving (1000–2000 km s −1 ) He-rich polar material and slow-moving (∼400 km s −1 ) equatorially distributed H-rich material. He II features also appear during the second light curve peak and evolve rapidly. Shock-driven models fit to the multiband photometry suggest that the event is powered by interaction with ∼5–6 M ⊙ of CSM, with 2–3 M ⊙ associated with each light curve peak, expelled during mass-loss episodes ∼3–4 yr and ∼1–2 yr prior to explosion. The observed precursor emission, combined with the extreme mass-loss rates required to power each light curve peak, favors either super-Eddington accretion onto a black hole or multiple long-lived eruptions from a massive star to luminosities that have not been previously observed. We consider multiple progenitor scenarios for SN 2023zkd, and find that the brightening optical precursor and inferred explosion properties are most consistent with a massive ( M ZAMS ≥ 30 M ⊙ ) and partially stripped He star undergoing an instability-induced merger with a black hole companion.}, archive = {J_ApJ}, author = {A. Gagliano and V. A. Villar and T. Matsumoto and D. O. Jones and C. L. Ransome and A. E. Nugent and D. Hiramatsu and K. Auchettl and D. Tsuna and Y. Dong and S. Gomez and P. D. Aleo and C. R. Angus and T. de Boer and K. A. Bostroem and K. C. Chambers and D. A. Coulter and K. W. Davis and J. R. Fairlamb and J. Farah and D. Farias and R. J. Foley and C. Gall and H. Gao and E. P. Gonzalez and D. A. Howell and M. E. Huber and C. D. Kilpatrick and C.-C. Lin and T. B. Lowe and M. E. MacLeod and E. A. Magnier and C. McCully and P. Mínguez and G. Narayan and M. Newsome and K. C. Patra and A. Rest and S. Rest and S. Smartt and K. W. Smith and G. Terreran and R. J. Wainscoat and Q. Wang and S. K. Yadavalli and Y. Zenati}, doi = {10.3847/1538-4357/adea38}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {182}, shortjournal = {The Astrophys. J.}, title = {Evidence for an instability-induced binary merger in the double-peaked, helium-rich type IIn supernova 2023zkd}, volume = {989}, year = {2025}, }
• (2025). Strict limits on potential secondary atmospheres on the temperate rocky exo-earth TRAPPIST-1 d. ApJ, 989(2), 181. (www)

  @article{ , abstract = {The nearby TRAPPIST-1 system, with its seven small rocky planets orbiting a late-type M8 star, offers an unprecedented opportunity to search for secondary atmospheres on temperate terrestrial worlds. In particular, the 0.8 R ⊕ TRAPPIST-1 d lies at the edge of the habitable zone ( T eq,A=0.3 = 262 K). Here we present the first 0.6–5.2 μ m NIRSpec/PRISM transmission spectrum of TRAPPIST-1 d from two transits with JWST. We find that stellar contamination from unocculted bright heterogeneities introduces 500–1000 ppm visit-dependent slopes, consistent with constraints from the out-of-transit stellar spectrum. Once corrected, the transmission spectrum is flat within ±100–150 ppm, showing no evidence for a haze-like slope or molecular absorption despite NIRSpec/PRISM’s sensitivity to CH 4 , H 2 O, CO, SO 2 , and CO 2 . Our observations exclude clear, hydrogen-dominated atmospheres with high confidence (>3 σ ). We leverage our constraints on even trace amounts of CH 4 , H 2 O, and CO 2 to further reject high mean molecular weight compositions analogous to a haze-free Titan, a cloud-free Venus, early Mars, and both Archean Earth and a cloud-free modern Earth scenario (>95% confidence). If TRAPPIST-1 d retains an atmosphere, it is likely extremely thin or contains high-altitude aerosols, with water cloud formation at the terminator predicted by 3D global climate models. Alternatively, if TRAPPIST-1 d is airless, our evolutionary models indicate that TRAPPIST-1 b, c, and d must have formed with ≲4 Earth oceans of water, though this would not preclude atmospheres on the cooler habitable-zone planets TRAPPIST-1 e, f, and g.}, archive = {J_ApJ}, author = {Caroline Piaulet-Ghorayeb and Björn Benneke and Martin Turbet and Keavin Moore and Pierre-Alexis Roy and Olivia Lim and René Doyon and Thomas J. Fauchez and Loïc Albert and Michael Radica and Louis-Philippe Coulombe and David Lafrenière and Nicolas B. Cowan and Danika Belzile and Kamrul Musfirat and Mehramat Kaur and Alexandrine L’Heureux and Doug Johnstone and Ryan J. MacDonald and Romain Allart and Lisa Dang and Lisa Kaltenegger and Stefan Pelletier and Jason F. Rowe and Jake Taylor and Jake D. Turner}, doi = {10.3847/1538-4357/adf207}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {181}, shortjournal = {The Astrophys. J.}, title = {Strict limits on potential secondary atmospheres on the temperate rocky exo-earth TRAPPIST-1 d}, volume = {989}, year = {2025}, }
• (2025). Validating an atmospheric absorption model through solar instrumentation on sounding rockets. ApJ, 989(2), 180. (www)

  @article{ , abstract = {Extreme-ultraviolet and X-ray data taken from suborbital sounding rocket platforms are affected by atmospheric absorption. The absorption correction factor varies with time, launch location, launch profile, and atmospheric conditions. This discussion is the first application of our spherical shell model for computing atmospheric absorption features. We find good agreement between the predicted and observed absorption in the first two flights of the High-resolution Coronal Imager sounding rocket instrument. We also find that the model agrees with the near-negligible absorption found at the longer wavelengths observed with the Marshall Grazing Incidence X-ray Spectrometer X-ray spectra. We now intend to explore the results from past and future missions, apply this model with greater confidence, and uncover novel insights.}, archive = {J_ApJ}, author = {Nicolas G. Donders and P. S. Athiray and Amy R. Winebarger and Sabrina L. Savage and Dyana L. Beabout and Gary P. Zank}, doi = {10.3847/1538-4357/ade5af}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {180}, shortjournal = {The Astrophys. J.}, title = {Validating an atmospheric absorption model through solar instrumentation on sounding rockets}, volume = {989}, year = {2025}, }
• (2025). Testing a new star formation history model from principal component analysis to facilitate spectral synthesis modeling. ApJ, 989(2), 179. (www)

  @article{ , abstract = {The spectrum of a galaxy is a complicated convolution of many properties of the galaxy, such as the star formation history (SFH), initial mass function, and metallicity. Inferring galaxy properties from the observed spectrum via spectral synthesis modeling is thus challenging. In particular, a simple yet flexible model for the SFH is required to obtain unbiased inferences. In this paper, we use SFHs from the IllustrisTNG and EAGLE simulations to test SFH models in terms of their capability of describing the simulated SFHs and the spectra generated from them. In addition to some commonly used SFH models (Γ, τ , and nonparametric), we also examine a model developed from principal component analysis (PCA), trained by a set of SFHs from IllustrisTNG. We find that when using the first five principal components (eigenhistories), the PCA-based models can achieve a good balance between simplicity and accuracy. Among the models tested, the PCA-based model provides high flexibility, by capturing diverse and complex simulated SFHs. To accurately reproduce spectra generated from the simulated SFHs, it is necessary to have a degree of freedom to describe the most recent SFH (e.g., a step function covering the age of 0–0.3 Gyr). Overall, the PCA+step model performs well in capturing the diversity of SFHs and reproducing the associated spectra, suggesting it is a promising and reliable approach for spectral synthesis modeling.}, archive = {J_ApJ}, author = {Yanzhe Zhang and H. J. Mo and Katherine E. Whitaker and Shuang Zhou}, doi = {10.3847/1538-4357/adeb70}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {179}, shortjournal = {The Astrophys. J.}, title = {Testing a new star formation history model from principal component analysis to facilitate spectral synthesis modeling}, volume = {989}, year = {2025}, }
• (2025). Survivors and zombies: The quenching and disruption of satellites around milky way analogs. ApJ, 989(2), 178. (www)

  @article{ , abstract = {It is necessary to understand the full accretion history of the Milky Way in order to contextualize the properties of observed Milky Way satellite galaxies and the stellar halo. This paper compares the dynamical properties and star formation histories of surviving and disrupted satellites around Milky Way–like galaxies using the D.C. Justice League suite of very high-resolution cosmological zoom-in simulations of Milky Way analogs and their halo environments. We analyze the full census of galaxies accreted within the past 12 Gyr, including both surviving satellites at z = 0, and dwarf galaxies that disrupted and merged with the host prior to z = 0. Our simulations successfully reproduce the trends in M * −[Fe/H]−[ α /Fe] observed in surviving Milky Way satellites and disrupted stellar streams, indicating earlier star formation for disrupted progenitors. We find the likelihood and timescales for quenching and disruption are strongly correlated with the mass and time of infall. In particular, none of the galaxies accreted more than 12 Gyr ago survived, and only 20% of all accreted galaxies with M * > 10 8 M ⊙ survive. Additionally, satellites with highly radial trajectories are more likely to quench and disrupt. Disruption proceeds quickly for ≥10 6 M ⊙ satellites accreted 10–12 Gyr ago, often on timescales similar to the ∼300 Myr snapshot spacing. For high-mass satellites, the disruption timescale is faster than the quenching timescale. As a result, 92% of disrupted galaxies remain star forming up until disruption. In contrast, ultrafaint dwarfs (UFDs) tend to quench prior to accretion, and 94% of UFDs accreted up to 12 Gyr ago survive at z = 0.}, archive = {J_ApJ}, author = {Debosmita Pathak and Charlotte R. Christensen and Alyson M. Brooks and Ferah Munshi and Anna C. Wright and Courtney Carter}, doi = {10.3847/1538-4357/adec94}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {178}, shortjournal = {The Astrophys. J.}, title = {Survivors and zombies: The quenching and disruption of satellites around milky way analogs}, volume = {989}, year = {2025}, }
• (2025). Rotation signatures of TESS B-type stars: Enlarging the sample. ApJ, 989(2), 177. (www)

  @article{ , abstract = {Massive stars are essential for the evolution and chemical enrichment of the universe, yet their structure and evolution remain poorly understood. This study aims to expand the sample of B-type stars with known rotation periods by analyzing NASA’s Transiting Exoplanet Survey Satellite (TESS) light curves (LCs). The analysis encompasses 373 B-type stars observed with 2 minute cadence LCs from TESS, employing a manifold approach that integrates three techniques: the Fast Fourier Transform, the Lomb–Scargle periodogram, and wavelet analysis. Rotational periods were identified for 14 new B-type stars in the TESS data, while periods for 16 previously studied targets were confirmed based on literature data. Among the remaining 343 stars, as a byproduct of our analysis, we have identified 36 pulsating candidates, seven with binary signatures, and 48 hot subdwarf (sdB) candidates. Integrating these three techniques offers a robust method for separating stellar rotation from other sources of variability in the LCs, such as pulsation, binarity, and sdB. Finally, the rotational periodicities identified in this study could provide valuable constraints for refining stellar evolution models, particularly those that include rotation and advancing asteroseismic analyses of massive stars.}, archive = {J_ApJ}, author = {J. P. S. Campelo and B. L. Canto Martins and I. C. Leão and D. O. Fontinele and R. L. Gomes and Y. S. Messias and E. Janot-Pacheco and L. A. Almeida and A. C. Brito and C. E. Ferreira Lopes and J. R. De Medeiros}, doi = {10.3847/1538-4357/adef2f}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {177}, shortjournal = {The Astrophys. J.}, title = {Rotation signatures of TESS B-type stars: Enlarging the sample}, volume = {989}, year = {2025}, }
• (2025). Multiwavelength constraints on dust dynamics and size evolution in protoplanetary disk rings. i. method. ApJ, 989(2), 176. (www)

  @article{ , abstract = {Observations with the Atacama Large Millimeter/submillimeter Array and the Jansky Very Large Array have revealed many dust rings in protoplanetary disks, often interpreted as dust traps at gas pressure bumps. Previous studies have typically modeled these rings by assuming a single dust species in drift–diffusion equilibrium, neglecting dust size evolution resulting from coagulation and fragmentation. In this work, we perform numerical simulations that incorporate both dust-gas dynamics (drift and diffusion) and dust size evolution. Our results show that the radial distributions of different dust species (up to the fragmentation limit) are nearly identical in the dust ring, as dust growth dominates over drift and diffusion (e.g., with a typical dust-to-gas ratio of ∼ 10 −2 ). Building on this finding, we develop a comprehensive, self-consistent analytical theory that describes the dust ring structure while explicitly accounting for size evolution effects. Our model provides a unified framework for interpreting multiwavelength observations by linking the physical dust distribution to the observed ring properties, thus laying the foundation for future observational modeling.}, archive = {J_ApJ}, author = {Linhan Yang and Ya-Ping Li and Ruobing Dong and Kiyoaki Doi and Hauyu Baobab Liu and Pinghui Huang}, doi = {10.3847/1538-4357/adf0fa}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {176}, shortjournal = {The Astrophys. J.}, title = {Multiwavelength constraints on dust dynamics and size evolution in protoplanetary disk rings. i. method}, volume = {989}, year = {2025}, }
• (2025). A 3D nonequilibrium ionization model of a shock wave in the low corona. i. extreme-ultraviolet emission and inefficient electron heating. ApJ, 989(2), 175. (www)

  @article{ , abstract = {Shocks in the low corona are best observed in the extreme ultraviolet (EUV); however, time-dependent ionization in the postshock region is generally incompatible with the otherwise straightforward plasma diagnostics typically applied to EUV imaging data. As a result, these rich data are largely underutilized. In this work, we present our approach to modeling the evolving EUV emission from coronal shocks, including nonequilibrium ionization (NEI) effects in the shocked plasma. Our framework combines (1) a 3D reconstruction of the shock geometry and kinematics derived from Solar Dynamics Observatory Atmospheric Imaging Assembly and STEREO-A/EUVI imaging, with (2) a simulated MHD snapshot of the pre-eruption corona built from magnetogram data, to solve Rankine–Hugoniot jump conditions. We then (3) track the density, temperature, and ionization history of the expanding 3D downstream region from which we generate synthetic postshock EUV light curves. We model the 2010 June 13 coronal mass ejection and shock wave using this framework, where we find that NEI is necessary to replicate the observed time-dependent EUV signal. This is especially true for the observed AIA 193 Å and 211 Å shock emission given that the predicted postshock temperatures would result in little Fe XII and Fe XIV . Moreover, the EUV model is highly sensitive to the postshock electron-to-ion temperature ratio ( T e / T p ). We find that the data are well described by the model and broadly prefer lower T e / T p < 1, suggesting inefficient electron heating throughout most of the shock structure.}, archive = {J_ApJ}, author = {Nicolas Trueba and John C. Raymond and Cooper Downs and Susan T. Lepri and Katharine K. Reeves and Yeimy J. Rivera and Maurice L. Wilson and Chengcai Shen}, doi = {10.3847/1538-4357/ade682}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {175}, shortjournal = {The Astrophys. J.}, title = {A 3D nonequilibrium ionization model of a shock wave in the low corona. i. extreme-ultraviolet emission and inefficient electron heating}, volume = {989}, year = {2025}, }
• (2025). Thermodynamic constraints on solar wind radial profiles. ApJ, 989(2), 174. (www)

  @article{ , abstract = {In this paper, we use thermodynamics to develop the radial density profile of the solar wind, which is described by kappa distributions. First, we show the connection of kappa distributions with polytropic processes, emphasizing the two “paths”—i.e., a kappa distribution of particle energies designates a polytropic relationship among the plasma moments, and, conversely, a polytropic relationship among plasma moments designates a kappa distribution of particle energies. We consider a radially dependent bulk speed and the various Hamiltonian terms for the solar wind. This generalizes earlier approaches that allowed for only a simple radially dependent potential energy and a constant bulk speed. Then, we study the profiles of density and other thermodynamic parameters and show how these can be used to determine unmeasured or missing solar wind parameters. As a proof of concept, an example analysis is performed to determine the magnetic field magnitude from observations of the plasma moments and validated with Voyager observations.}, archive = {J_ApJ}, author = {G. Livadiotis and D. J. McComas}, doi = {10.3847/1538-4357/adea44}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {174}, shortjournal = {The Astrophys. J.}, title = {Thermodynamic constraints on solar wind radial profiles}, volume = {989}, year = {2025}, }
• (2025). AT 2019aalc: A bowen fluorescence flare with a precursor flare in an active galactic nucleus. ApJ, 989(2), 173. (www)

  @article{ , abstract = {AT 2019aalc is a peculiar sequence of highly variable emission events observed towards the nucleus of the broad-line active galactic nucleus (AGN) SDSS J152416.66+045119.0. The system exhibited two distinct UV-optical flares (the first detected in 2019, the second one in 2023). Spectra obtained following the detection of the second flare revealed prominent Bowen fluorescence (BF) and high-ionization coronal emission lines, which were much weaker, if at all detectable, in a spectrum taken following the first flare. We present and analyze a large set of multi-wavelength, multi-epoch data for this source, with particular emphasis on optical spectroscopic monitoring conducted with the Las Cumbres Observatory network. During the relatively slow dimming that followed the second optical flare, the UV-optical light curve shows a sequence of minor rebrightening events, while the BF and the coronal lines vary (roughly) in tandem with these “bumps” in the broadband light curve. Most of the observed behavior of AT 2019aalc links it to the growing class of BF flares while setting it apart from canonical tidal disruption events. However, AT 2019aalc has some outstanding peculiarities, including two short flares seen in its soft X-ray light-curve during the dimming phase of the second optical flare, and which do not seem to be linked to the emission line variations. We discuss the optical and X-ray properties of the source and possible scenarios of the origin of the flare, in particular radiation pressure instabilities in the (preexisting) AGN accretion disk.}, archive = {J_ApJ}, author = {Marzena Śniegowska and Benny Trakhtenbrot and Lydia Makrygianni and Iair Arcavi and Claudio Ricci and Sara Faris and Biswaraj Palit and D. Andrew Howell and Megan Newsome and Joseph Farah and Curtis McCully and Estefania Padilla-Gonzalez and Giacomo Terreran}, doi = {10.3847/1538-4357/aded13}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {173}, shortjournal = {The Astrophys. J.}, title = {AT 2019aalc: A bowen fluorescence flare with a precursor flare in an active galactic nucleus}, volume = {989}, year = {2025}, }
• (2025). Time-integrated polarizations of the GRB X-ray flares. ApJ, 989(2), 172. (www)

  @article{ , abstract = {Despite decades of studies, the energy dissipation mechanism of the X-ray flares in the afterglow phase of gamma-ray bursts (GRBs) is still debated. If the jet is dominated by the Poynting flux, there would be a large-scale ordered magnetic field in it, and the X-ray flares might be powered by the magnetic reconnection process. However, if the jet is dynamical energy dominated and the magnetic field is random, the X-ray flares may be generated by the internal shocks of the cold outflow or by the synchrotron emission escaping from the hot plasma. Polarization is very sensitive to the magnetic field configuration in the radiation region; hence, it can be used as a probe of the magnetic field and the corresponding energy dissipation mechanism in the radiation region. In this paper, the magnetic reconnection model, the internal shock model, and the photosphere model are all described by a simple parametric model to study the time-integrated polarizations of the GRB X-ray flares. We found the time-integrated polarization degree of the GRB X-ray flares would concentrate on high values for the magnetic reconnection process and around zero for the internal shock or the photosphere origin. The influences of the parameters on the time-integrated polarizations are also discussed. Therefore, the statistical properties of the polarizations obtained by the dedicated polarization detector, Low-energy Polarimetry Detector on board POLAR-2, would make a distinction of the energy dissipation processes in the radiation region of the GRB X-ray flares.}, archive = {J_ApJ}, author = {Xing-Yao Wang and Mi-Xiang Lan}, doi = {10.3847/1538-4357/adee19}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {172}, shortjournal = {The Astrophys. J.}, title = {Time-integrated polarizations of the GRB X-ray flares}, volume = {989}, year = {2025}, }
• (2025). Radiative flux from a high-resolution atmospheric dynamics simulation of a hot jupiter for JWST and ariel. ApJ, 989(2), 171. (www)

  @article{ , abstract = {We present medium-wave (∼0.5–13 μ m) radiative flux distributions and spectra derived from high-resolution atmospheric dynamics simulations of an exoplanet, WASP-121 b. This planet serves to illustrate several important features. Assuming different chemical compositions for its atmosphere (e.g., H 2 /He only and Z ∈ {1, 12} times solar metallicity), the outgoing radiative flux is computed using full radiative transfer that folds in the James Webb Space Telescope (JWST) and Ariel instrument characteristics. We find that the observed variability depends strongly on the assumed chemistry and the instrument wavelength range, hence the probed altitude of the atmosphere. With H 2 /He only, the flux and variability originate near the 10 5 Pa level; with solar and higher metallicity, the ∼10 3 Pa level is probed, and the variability is distinguishably reduced. Our calculations show that JWST and Ariel have the sensitivity to capture the atmospheric variability of exoplanets like WASP-121 b, depending on the metallicity—both in repeated eclipse and phase-curve observations.}, archive = {J_ApJ}, author = {Jagat Kafle and James Y-K. Cho and Quentin Changeat}, doi = {10.3847/1538-4357/adef02}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {171}, shortjournal = {The Astrophys. J.}, title = {Radiative flux from a high-resolution atmospheric dynamics simulation of a hot jupiter for JWST and ariel}, volume = {989}, year = {2025}, }
• (2025). Stellar models also limit exoplanet atmosphere studies in emission. ApJ, 989(2), 170. (www)

  @article{ , abstract = {Stellar contamination has long been recognized as a major bottleneck in transmission spectroscopy, limiting our ability to accurately characterize exoplanet atmospheres—particularly for terrestrial worlds. In response, significant observational efforts have shifted toward emission spectroscopy as a potentially more robust alternative, exemplified by initiatives such as the 500 hr JWST Rocky Worlds Director’s Discretionary Time program. However, the extent to which emission spectroscopy may be affected by stellar effects remains mostly unexplored, in stark contrast with the extensive exploration and mitigation work for transmission spectroscopy. In this study, we assess the impact of imperfect knowledge of stellar spectra on exoplanet atmospheric retrievals from emission spectroscopy. At 12.8 μ m, none of the considered bare surface types—basalt, ultramafic, Fe oxidized, and granitoid—can be reliably distinguished when accounting for the 3 σ model precision between SPHINX and PHOENIX. At 15.0 μ m, only the granitoid surface is distinguishable from all others above this threshold. These results show that stellar model uncertainty alone substantially limits our ability to constrain surface composition from photometric data, even before including other sources of uncertainty, such as stellar radius. Also, we find that current 15 μ m eclipse depth estimations using different stellar models introduce a 60 ppm difference for M8 and 20 ppm for M5 stars. This model discrepancy leads to a degeneracy in retrieved planetary albedos and weakens constraints on the presence of an atmosphere. We therefore recommend that future JWST secondary eclipse observations systematically include stellar mid-IR spectroscopy to mitigate these uncertainties.}, archive = {J_ApJ}, author = {Thomas J. Fauchez and Elsa Ducrot and Benjamin V. Rackham and Kevin B. Stevenson and L. C. Mayorga and Julien de Wit}, doi = {10.3847/1538-4357/adf068}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {170}, shortjournal = {The Astrophys. J.}, title = {Stellar models also limit exoplanet atmosphere studies in emission}, volume = {989}, year = {2025}, }
• (2025). The HETDEX survey: Probing neutral hydrogen in the circumgalactic medium of ∼88,000 lyα emitters. ApJ, 989(2), 169. (www)

  @article{ , abstract = {We explore the neutral hydrogen (H i ) gas around 1.9 < z < 3.5 Lyman alpha emitters (LAEs) from the Hobby–Eberly Telescope Dark Energy Experiment using faint Ly α absorption. This absorption is the result of H i in the halo of the LAE scattering Ly α photons from the integrated light of background galaxies along the line of sight. We stack millions of spectra from regions around ∼88,000 LAEs, in order to focus on the physics of the gas at large radii. The extensive number of fiber spectra contributing to the stacks ensures a sufficient signal-to-noise ratio to detect the faint Ly α absorption, which would otherwise be buried within the noise. We detect absorption out to a projected ∼350 kpc around an average LAE at z ∼ 2.5. We use these results to create an empirical radial W λ (Ly α ) profile around LAEs. Comparison with numerical simulations reveals a profile similar to the empirical one within this region. Compared to previous studies, the profile is similar but modestly higher. We also outline a simple physical picture motivated by the observed trends in the data. We plan to quantify this radial profile as a function of redshift, local density, and Ly α luminosity, to explore the relationship between LAE environments and H i distribution.}, archive = {J_ApJ}, author = {Mahan Mirza Khanlari and Karl Gebhardt and Laurel H. Weiss and Dustin Davis and Erin Mentuch Cooper and Mahdi Qezlou and Maja Lujan Niemeyer and Robin Ciardullo and Donald P. Schneider and Shiro Mukae and Chenxu Liu and Daniel Farrow and Gary J. Hill and Gregory R. Zeimann and Wolfram Kollatschny}, doi = {10.3847/1538-4357/adf10e}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {169}, shortjournal = {The Astrophys. J.}, title = {The HETDEX survey: Probing neutral hydrogen in the circumgalactic medium of ∼88,000 lyα emitters}, volume = {989}, year = {2025}, }
• (2025). X-ray reflection spectroscopy with improved calculations of the emission angle. ApJ, 989(2), 168. (www)

  @article{ , abstract = {The reflection spectrum produced by a cold medium illuminated by X-ray photons is not isotropic and its shape depends on the emission angle. In the reflection spectrum of an accretion disk of a black hole, the value of the emission angle changes over the disk and, in general, is different from the value of the inclination angle of the disk because of the light bending in the strong gravitational field of the black hole. Current reflection models make some approximations, as calculating a reflection spectrum taking the correct emission angle at every point of the disk into account would be too time-consuming and make the model too slow to analyze observations. In a recent paper, we showed that these approximations are unsuitable to fit high-quality black hole spectra expected from the next generation of X-ray missions. Here, we present a reflection model with improved calculations of the emission angle that solves this problem.}, archive = {J_ApJ}, author = {Yimin Huang and Honghui Liu and Temurbek Mirzaev and Ningyue Fan and Cosimo Bambi and Zuobin Zhang and Thomas Dauser and Javier A. García and Adam Ingram and Jiachen Jiang and Guglielmo Mastroserio and Shafqat Riaz and Swarnim Shashank}, doi = {10.3847/1538-4357/adf111}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {168}, shortjournal = {The Astrophys. J.}, title = {X-ray reflection spectroscopy with improved calculations of the emission angle}, volume = {989}, year = {2025}, }
• (2025). Additional evidence for the existence of a primordial disk system. ApJ, 989(2), 167. (www)

  @article{ , abstract = {The origin of very metal-poor (VMP; [Fe/H] ≤ −2.0) stars on planar orbits has been the subject of great attention since their first discovery. However, prior to the release of the Gaia BP/RP (XP) spectra and large photometric samples such as SkyMapper, SAGES, J-PLUS, and S-PLUS, most studies have been limited due to their small sample sizes or strong selection effects. Here, we crossmatch photometric metallicities derived from Gaia XP synthetic photometry and geometric distances from Bailer-Jones et al., and select 12,000 VMP stars (1604 dwarfs and 10,396 giants) with available high-quality astrometry. After calculating dynamical parameter estimates using AGAMA , we employ the nonnegative matrix factorization technique to the v ϕ distribution across bins in {Z}_{{\rm{\max }}} (the maximum height above or below the Galactic plane during the stellar orbit). We find three primary populations of the selected VMP stars: halo, disk system, and the Gaia Sausage/Enceladus structure. The fraction of disk-like stars decreases with increasing {Z}_{{\rm{\max }}} (as expected), although it is still ∼20% for stars with {Z}_{{\rm{\max }}} ∼ 3 kpc. Similar results emerge from the application of the Hayden criterion, which separates stellar populations on the basis of their orbital inclination angles relative to the Galactic plane. We argue that such high fractions of disk-like stars indicate that they are an independent component, rather than originating solely from Galactic building blocks or heating by minor mergers. We suggest that most of these VMP stars are members of the hypothesized “primordial” disk.}, archive = {J_ApJ}, author = {Shuai Xu and Haibo Yuan and Bowen Huang and Timothy C. Beers and Yang Huang and Maosheng Xiang and Kai Xiao and Jihye Hong and Young Sun Lee and Wuming Yang}, doi = {10.3847/1538-4357/adf193}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {167}, shortjournal = {The Astrophys. J.}, title = {Additional evidence for the existence of a primordial disk system}, volume = {989}, year = {2025}, }
• (2025). X-ray observations of nova sco 2023: Spectroscopic evidence of charge exchange. ApJ, 989(2), 166. (www)

  @article{ , abstract = {The supersoft source phase of a nova eruption, observed a few days after the outburst, usually displays an absorbed X-ray thermal continuum with absorption features, emitted by the white dwarf atmosphere. However, the X-ray spectra of many novae in this phase display additional emission lines that likely originate from shocks in the novae ejecta. When the shocked plasma interacts with cold gas, narrow radiative recombination continua (RRCs) and charge exchange (CX) emission are observed. We present the analysis of high-resolution Chandra Low Energy Transmission Grating X-ray grating spectra of Nova Sco 2023, observed 128 and 183 days after the optical peak in 2023 August and October. At both epochs, the absorbed X-ray thermal continuum is well described by a nonlocal thermal equilibrium atmosphere model with a temperature T ≃ 750,000 K ( kT ≃ 65 eV). On day 128, the atmosphere is found to be outflowing at v ≃ −3500 km s −1 . On day 183, the atmosphere brightened by a factor of ∼2 and slowed down to v ≃ −1500 km s −1 . The discrete emission features of the spectrum consist of the C +5 , N +5 , and N +6 RRCs, indicating a cold electron temperature of kT e ≃ 1 eV on day 128 and kT e ≃ 20 eV on day 183. The observed line series of H-like and He-like C +5 , N +5 , N +6 , and O +6 show enhanced intensities of high- n (principal quantum number) transitions, consistent with a CX model of hot ions at kT ∼ 100 eV. The velocity shift of the CX lines remained at v ∼ ±3000 km s −1 , which can be explained by a bipolar outflow. After Nova Ret 2020 (YZ Ret), Nova Sco 2023 is yet another nova in which we have found exquisite evidence of CX in astrophysical ionized plasma.}, archive = {J_ApJ}, author = {Sharon Mitrani and Ehud Behar and Marina Orio and Jack Worley}, doi = {10.3847/1538-4357/adf1a3}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {166}, shortjournal = {The Astrophys. J.}, title = {X-ray observations of nova sco 2023: Spectroscopic evidence of charge exchange}, volume = {989}, year = {2025}, }
• (2025). Detection of X-ray polarization in the hard state of IGR j17091-3624: Spectropolarimetric study with IXPE and NuSTAR data. ApJ, 989(2), 165. (www)

  @article{ , abstract = {The class-transition Galactic X-ray binary IGR J17091–3624 was simultaneously monitored by the Imaging X-ray Polarimetry Explorer (IXPE) and NuSTAR satellites. We present a detailed spectropolarimetric study of the source using data from both satellites covering the period from 2025 March 7 to 10. A polarimetric analysis in the 2–8 keV band using a model-independent method reveals a significant detection of polarization degree (PD) of (11.3 ± 2.35)% at a polarization angle (PA) of 82\mathop{.}\limits^{^\circ }7\pm 5\mathop{.}\limits^{^\circ }96 (significant at >4 σ ). The model-dependent polarization analysis using the polconst and polpow models yields consistent values of PD and PA. In both methods, an energy-dependent increasing trend of PD is observed. In the 6–8 keV band, a maximum PD of (29.9 ± 8.46)% (significant at >3 σ ) is detected at a PA of 88 \mathop{.}\limits^{\unicode{x000b0}} 0 ± 8 \mathop{.}\limits^{\unicode{x000b0}} 15 (>3 σ ). The joint spectral analysis using IXPE and NuSTAR data in the 2–70 keV band was performed with four different sets of phenomenological and physical models. Our results indicate a strong dominance of nonthermal photons originating from a “hot” Compton cloud, suggesting that the source was in a hard spectral state. Spectral fitting with the physical kerrbb and TCAF models provides an estimate of the black hole mass {M}_{{\rm{BH}}}=14.{8}_{-3.4}^{+4.7}\,{M}_{\odot } and dimensionless spin parameter a * ∼ 0.54. The requirement of a higher hydrogen column density in the spectral fit of the second NuSTAR observation is attributed to the obscuration of nonthermal photons during the dip phase, likely caused by the presence of wind accreted from the companion star.}, archive = {J_ApJ}, author = {Dipak Debnath and Subham Srimani and Hsiang-Kuang Chang}, doi = {10.3847/1538-4357/adf1e6}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {165}, shortjournal = {The Astrophys. J.}, title = {Detection of X-ray polarization in the hard state of IGR j17091-3624: Spectropolarimetric study with IXPE and NuSTAR data}, volume = {989}, year = {2025}, }
• (2025). Generation of sunward ion cyclotron waves and the nature of right-handed polarized ion-scale waves in the near-sun solar wind. ApJ, 989(2), 164. (www)

  @article{ , abstract = {Observations from the Parker Solar Probe have revealed the ubiquitous presence of right-handed polarized waves in the near-Sun solar wind. While antisunward fast-magnetosonic whistler waves have been commonly considered as their source, sunward ion cyclotron waves (ICWs) are another plausible candidate. Sunward ICWs can directly interact with antisunward ions via cyclotron resonant interactions, suggesting they may play an important role in particle energization processes in the solar wind. However, the generation of sunward ICWs remains poorly understood. In this study, we perform a theoretical instability survey over a broad parameter space to investigate the conditions that favor the generation of sunward ICWs, focusing on two key plasma properties: the temperature anisotropy and the relative streaming speed of the proton beam component. Our results show that sunward ICWs can be excited by proton beams with slow streaming speeds but significant temperature anisotropy. Additionally, the analysis reveals that the growth of this instability is strongly suppressed in environments with high alpha particle concentrations, indicating that sunward ICWs preferentially arise in plasmas with low alpha particle abundance. These findings offer new insights into the generation and nature of ion-scale waves in the near-Sun solar wind.}, archive = {J_ApJ}, author = {Chen Shi and Jinsong Zhao and Yifan Wu and Si Liu and Fuliang Xiao and Huasheng Xie}, doi = {10.3847/1538-4357/adf43d}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {164}, shortjournal = {The Astrophys. J.}, title = {Generation of sunward ion cyclotron waves and the nature of right-handed polarized ion-scale waves in the near-sun solar wind}, volume = {989}, year = {2025}, }
• (2025). Discoveries of fine structures and secondary pulses in coherent radio emission from a magnetic massive star. ApJ, 989(2), 163. (www)

  @article{ , abstract = {In this paper, we report auroral radio emission from a magnetic B star HD 142990 using the MeerKAT radio telescope at 900–1670 MHz. This star is known to produce such emission (observed as periodic radio pulses) via electron cyclotron maser emission (ECME). However, past studies on ECME from this star were confined to observations at specific rotational phase ranges where one expects to see such pulses. We, for the first time, observed the star for its one complete rotation cycle and discovered that the star also produces “off-pulse” emission, which we term as secondary enhancements. Two such enhancements were observed, one of which is left circularly polarized (LCP) and the other is right circularly polarized, the latter is confirmed to be persistent. Using simulation, we infer that such pulses are likely related to the large misalignment between the stellar rotation and magnetic dipole axes (>80°), leading to the formation of highly complex magnetospheric plasma distribution. In addition, by extracting dynamic spectra for the primary pulses, we discovered prominent fine structures in one of the LCP pulses, with timescales as small as the instrumental time resolution (8 s). This is the first time that such structures are seen from a magnetic hot star, and has the potential to reveal detailed information about how the emission is driven, and the nature of the elementary sources of radiation. To pinpoint the origin of these fine structures and their significance, higher time and spectral resolution observations should be conducted in the future.}, archive = {J_ApJ}, author = {Barnali Das and Poonam Chandra and William Cotton and Véronique Petit}, doi = {10.3847/1538-4357/aded88}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {163}, shortjournal = {The Astrophys. J.}, title = {Discoveries of fine structures and secondary pulses in coherent radio emission from a magnetic massive star}, volume = {989}, year = {2025}, }
• (2025). Where do solar storms prefer to originate from: Hemispheric and longitudinal patterns in solar cycles 23 and 24. ApJ, 989(2), 162. (www)

  @article{ , abstract = {Using synoptic maps, we analyzed the relationship between active longitudes, the most populated longitudes of energetic flares, the distribution of magnetically complex active regions, and the preferred locations of those that produced the largest flares. We found that solar activity was stronger in the northern hemisphere during the rising phases of both cycles, shifting to the southern hemisphere around solar maximum. In solar cycle 24, stronger activity returned to the northern hemisphere during the declining phase—a pattern not seen in cycle 23. Strong magnetic elements and large flares showed significant clustering along persistent active longitudes, particularly from the solar maximum through the declining phase. These active longitudes remained stable for four to nine Carrington rotations before shifting by approximately 160°–180°, and their evolution displayed clear periodic behavior with cycles ranging from 0.6 to 2.02 yr, consistently seen both in the magnetic and flare data. During the solar minimum between cycles 23 and 24, active longitudes clustered near 200° longitude for about 3 yr, with cycle 24 beginning with a dominant activity at this location. Furthermore, 71% of β – γ – δ -type active regions that produced X-class flares emerged along these active longitudes. This highlights their significance for the strongest solar eruptions and offers valuable potential information for midterm flare prediction in both hemispheric and longitudinal domains, even at the onset of new cycles.}, archive = {J_ApJ}, author = {Marianna B. Korsós and Robertus Erdélyi}, doi = {10.3847/1538-4357/adee97}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {162}, shortjournal = {The Astrophys. J.}, title = {Where do solar storms prefer to originate from: Hemispheric and longitudinal patterns in solar cycles 23 and 24}, volume = {989}, year = {2025}, }
• (2025). The 157 month Swift/BAT all-sky hard X-ray survey. ApJ, 989(2), 161. (www)

  @article{ , abstract = {The Burst Alert Telescope (BAT) on board the Neil Gehrels Swift Observatory has been serving as a survey instrument for the hard X-ray sky, and has detected thousands of X-ray sources (e.g., active galactic nuclei, X-ray binaries, etc). BAT monitors these X-ray sources and follows their light curves on timescales from minutes to years. In addition, BAT has discovered hundreds of new X-ray sources in survey images stacked throughout the mission lifetime. We present an updated BAT survey catalog since the last published BAT 105 month survey catalog with additional 4.5 yr of data until 2017 December. Data since 2007 are reprocessed to include updated instrumental calibrations. Analysis in this study shows that additional systematic noise can be seen in the 157 month mosaic images, resulting in decreases in the expected improvement in sensitivity and the number of new detections. The BAT 157 month survey reaches a sensitivity of 8.83 × 10 −12 erg s −1 cm −2 for 90% of the sky and 6.44 × 10 −12 erg s −1 cm −2 for 10% of the sky. This catalog includes spectra, and monthly and snapshot light curves in eight energy bands (14–20, 20–24, 24–35, 35–50, 50–75, 75–100, 100–150, and 150–195 keV) for 1888 sources, including 256 new detections above a detection threshold of 4.8 σ . The light curves, spectra, and tables that summarize the information of the detected-sources are available in the online journal and on the catalog web page: https://swift.gsfc.nasa.gov/results/bs157mon/ .}, archive = {J_ApJ}, author = {Amy Y. Lien and Hans A. Krimm and Craig B. Markwardt and Kyuseok Oh and Lea Marcotulli and Richard Mushotzky and Nicholas R. Collins and Scott D. Barthelmy and Wayne H. Baumgartner and S. Bradley Cenko and Michael Koss and Sibasish Laha and Takanori Sakamoto and David M. Palmer and Tyler Parsotan}, doi = {10.3847/1538-4357/ade676}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {161}, shortjournal = {The Astrophys. J.}, title = {The 157 month Swift/BAT all-sky hard X-ray survey}, volume = {989}, year = {2025}, }
• (2025). MIDIS: MIRI uncovers virgil, the first little red dot with clear detection of its host galaxy at z ≃ 6.6. ApJ, 989(2), 160. (www)

  @article{ , abstract = {We present Virgil, a Mid-Infrared Instrument (MIRI) extremely red object detected with the F1000W filter as part of the MIRI Deep Imaging Survey observations of the Hubble Ultra Deep Field. Virgil is an Ly α emitter (LAE) at z spec = 6.6312 ± 0.0019 (from the Very Large Telescope/MUSE) with a rest-frame UV-to-optical spectral energy distribution (SED) typical of LAEs at similar redshifts. However, MIRI observations reveal an unexpected extremely red color at rest-frame near-infrared (NIR) wavelengths, F444W − F1000W = 2.33 ± 0.06. Such a steep rise in the NIR, completely missed without MIRI imaging, is poorly reproduced by models including only stellar populations and hints toward the presence of an active galactic nucleus, although alternative explanations such as extreme dust obscuration and strong nebular continuum and emission lines contribution due to young stellar ages cannot be completely ruled out. According to the shape of its overall SED, Virgil belongs to the recently discovered population of little red dots but displays an extended rest-frame UV-optical wavelength morphology following a 2D-Sérsic profile with an average index of n=0.9{3}_{-0.31}^{+0.85} and {r}_{e}=0.4{9}_{-0.11}^{+0.05} pkpc. Only at MIRI wavelengths, Virgil is unresolved due to the coarser point-spread function. This discovery demonstrates the crucial importance of deep MIRI surveys to reveal the true nature and properties of high- z galaxies that otherwise would be misinterpreted and raises the question of how common Virgil-like objects could be in the early Universe.}, archive = {J_ApJ}, author = {Edoardo Iani and Pierluigi Rinaldi and Karina I. Caputi and Marianna Annunziatella and Danial Langeroodi and Jens Melinder and Pablo G. Pérez-González and Javier Álvarez-Márquez and Leindert A. Boogaard and Sarah E. I. Bosman and Luca Costantin and Thibaud Moutard and Luis Colina and Göran Östlin and Thomas R. Greve and Gillian Wright and Almudena Alonso-Herrero and Arjan Bik and Steven Gillman and Alejandro Crespo Gómez and Jens Hjorth and Sarah Kendrew and Alvaro Labiano and John P. Pye and Tuomo V. Tikkanen and Fabian Walter and Manuel Güdel and Thomas Henning and Paul P. van der Werf}, doi = {10.3847/1538-4357/ade5a6}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {160}, shortjournal = {The Astrophys. J.}, title = {MIDIS: MIRI uncovers virgil, the first little red dot with clear detection of its host galaxy at z ≃ 6.6}, volume = {989}, year = {2025}, }
• (2025). Decoding AGN feedback with X-arithmetic: From morphology to physical mechanisms. ApJ, 989(2), 159. (www)

  @article{ , abstract = {Feedback from active galactic nuclei is a key process in the evolution of massive halos in the Universe. New observational information on feedback is crucial for improving the implementation of the physics in numerical models. In this work, we apply a novel image-manipulation technique, termed “X-arithmetic,” to a sample of 15 galaxy clusters and groups deeply observed with Chandra. This technique decomposes perturbations in feedback-dominated regions into images excluding either (1) weak shocks and sound waves, (2) bubbles inflated by jets, or (3) cooling and slow gas motions (isobaric perturbations), enabling efficient spatial identification of these features without involving spectroscopic analysis. We confirm the nature of previously (spectroscopically) identified features and newly establish the origin of other structures. We find that feedback produces multiple shocks in groups and massive galaxies, but only one to two shocks in clusters. Prominent isobaric structures are abundant around inner cavities in clusters, compared to almost no such structures in groups. These differences suggest that feedback effects are stronger in smaller-mass systems, possibly due to the shallower gravitational potential of groups or more violent feedback. Follow-up spectroscopy, guided by the X-arithmetic results, suggests that earlier-identified “isothermal shocks” could be a mix of isobaric and adiabatic structures. We applied X-arithmetic to galaxy cluster simulations, demonstrating its straightforward application and future potential for testing the feedback physics details in simulations. Our feasibility study shows that imaging data from future X-ray observatories like AXIS will be ideal for expanding X-arithmetic application to a larger sample of objects.}, archive = {J_ApJ}, author = {Hannah McCall and Irina Zhuravleva and Eugene Churazov and Congyao Zhang and William Forman and Christine Jones and Yuan Li}, doi = {10.3847/1538-4357/adea67}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {159}, shortjournal = {The Astrophys. J.}, title = {Decoding AGN feedback with X-arithmetic: From morphology to physical mechanisms}, volume = {989}, year = {2025}, }
• (2025). Linearity of structure kernels in main-sequence and subgiant solar-like oscillators. ApJ, 989(2), 158. (www)

  @article{ , abstract = {Seismic structure inversions have been used to study the solar interior for decades. With the high-precision frequencies obtained using data from the Kepler mission, it has now become possible to study other solar-like oscillators using structure inversions, including both main-sequence and subgiant stars. Subgiant stars are particularly interesting because they exhibit modes of mixed acoustic-buoyancy nature, which provide the opportunity to probe the deeper region of stellar cores. This work examines whether the structure inversion techniques developed for the pure acoustic modes of the Sun and other main-sequence stars are still valid for mixed modes observed in subgiant stars. We construct two grids of models: one of main-sequence stars and one of early subgiant stars. Using these grids, we examine two different parts of the inversion procedure. First, we examine what we call the “kernel errors,” which measure how well the mode sensitivity functions can recover known frequency differences between two models. Second, we test how these kernel errors affect the ability of an inversion to infer known structure differences. On the main sequence, we find that reliable structure inversion results can be obtained across the entire range of masses and large frequency separations we consider. On the subgiant branch, however, the rapid evolution of mixed modes leads to large kernel errors and hence difficulty recovering known structure differences. Our tests show that using mixed modes to infer the structure of subgiant stars reliably will require improvements to current fitting approaches and modifications to the structure inversion techniques.}, archive = {J_ApJ}, author = {Lynn Buchele and Earl P. Bellinger and Saskia Hekker and Sarbani Basu}, doi = {10.3847/1538-4357/adec72}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {158}, shortjournal = {The Astrophys. J.}, title = {Linearity of structure kernels in main-sequence and subgiant solar-like oscillators}, volume = {989}, year = {2025}, }
• (2025). Anisotropy of nanohertz gravitational-wave background and source clustering from supermassive binary black holes based on cosmological simulation. ApJ, 989(2), 157. (www)

  @article{ , abstract = {Several pulsar timing array (PTA) groups have recently claimed the detection of nanohertz gravitational-wave background (GWB), but the origin of this gravitational-wave (GW) signal remains unclear. Nanohertz GWs generated by supermassive binary black holes (SMBBHs) are one of the most important GW sources in the PTA band. Utilizing data from cosmological simulation, we generate multiple realizations of a mock observable universe that self-consistently incorporates the cosmic large-scale structure, enabling a robust statistical analysis of SMBBH populations and their GW signatures. We systematically investigate the merger event distributions and both the isotropic and anisotropic properties of the resulting GWB signals under different hardening timescales. Specifically, we calculate the characteristic amplitude of the GWB signal, and the angular power spectrum for both the total energy density and the energy density in different frequency bins accounting for cosmic variance through different realizations. We also study the clustering pattern of the positional distribution of SMBBHs to examine whether they can reproduce the large-scale structure of galaxies. Furthermore, for the upcoming Chinese Pulsar Timing Array and Square Kilometre Array PTA, we predict the numbers and signal-to-noise ratio (SNR) distributions of resolvable individual GW sources that may be detected with SNR > 8. We finally investigate the impact of weak-lensing effects and find that their influence on the basic characteristics of the GWB signal and individual sources is rather limited.}, archive = {J_ApJ}, author = {Qing Yang and Xiao Guo and Zhoujian Cao and Xiaoyun Shao and Xi Yuan}, doi = {10.3847/1538-4357/aded02}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {157}, shortjournal = {The Astrophys. J.}, title = {Anisotropy of nanohertz gravitational-wave background and source clustering from supermassive binary black holes based on cosmological simulation}, volume = {989}, year = {2025}, }
• (2025). Cold gas and star formation in the phoenix cluster with JWST. ApJ, 989(2), 156. (www)

  @article{ , abstract = {We present integral field unit observations of the Phoenix Cluster with the JWST Mid-infrared Instrument’s Medium Resolution Spectrometer. We focus this study on the molecular gas, dust, and star formation in the brightest cluster galaxy (BCG). We use precise spectral modeling to produce maps of the silicate dust, molecular gas, and polycyclic aromatic hydrocarbons (PAHs) in the inner ∼50 kpc of the cluster. We measure the optical depth from silicates by comparing the observed H 2 line ratios to those predicted by excitation models. We provide updated measurements of the total molecular gas mass of 1.{9}_{-0.4}^{+0.5}\times 1{0}^{10} M ⊙ , which agrees with CO-based estimates, providing an estimate of the CO-to-H 2 conversion factor of {\alpha }_{{\rm{CO}}}=0.8\pm 0.2\,\,{M}_{\odot }\,{{\rm{pc}}}^{-2}\,{({\rm{K}}\,{\rm{km}}\,{{\rm{s}}}^{-1})}^{-1} ; an updated stellar mass of M * = 2.6 ± 0.5 × 10 10 M ⊙ ; and star formation rates (SFRs) averaged over 10 and 100 Myr of 〈SFR〉 10 = 1340 ± 100 M ⊙ yr −1 and 〈SFR〉 100 = 740 ± 80 M ⊙ yr −1 , respectively. The H 2 emission seems to be powered predominantly by shocks and star formation within the central ∼20 kpc, induced by stellar feedback and radio jets from the active galactic nucleus. Additionally, we find nearly an order-of-magnitude drop in the SFRs estimated by PAH fluxes in cool core BCGs compared to field galaxies, suggesting that hot particles from the intracluster medium are destroying PAH grains even in the central-most tens of kiloparsecs.}, archive = {J_ApJ}, author = {Michael Reefe and Michael McDonald and Marios Chatzikos and Jerome Seebeck and Richard Mushotzky and Sylvain Veilleux and Steven W. Allen and Matthew Bayliss and Michael Calzadilla and Rebecca Canning and Megan Donahue and Benjamin Floyd and Massimo Gaspari and Julie Hlavacek-Larrondo and Brian McNamara and Helen Russell and Arnab Sarkar and Keren Sharon and Taweewat Somboonpanyakul}, doi = {10.3847/1538-4357/aded90}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {156}, shortjournal = {The Astrophys. J.}, title = {Cold gas and star formation in the phoenix cluster with JWST}, volume = {989}, year = {2025}, }
• (2025). High-energy neutrino emission from a radiatively inefficient accretion flow with a three-dimensional general relativistic magnetohydrodynamic simulation. ApJ, 989(2), 155. (www)

  @article{ , abstract = {The high-energy particle production in the accretion flow onto black holes can be key physics to explain the high-energy neutrino background. While the single-zone approximation has been commonly adopted in studies of the high-energy neutrino emission around black holes, the effects of the global plasma structure may be nonnegligible. We carry out the first computations of cosmic-ray acceleration and high-energy neutrino emission via the hadronuclear ( pp ) interaction in global radiatively inefficient accretion flows and outflows around a supermassive black hole, using three-dimensional general relativistic magnetohydrodynamic simulation data. The Fokker–Planck equation for cosmic-ray protons is solved with a phenomenological model for the energy diffusion coefficient to express the turbulent acceleration in the subgrid scale. The inhomogeneous and time variable structure of the accretion flow leads to a variety of particle energy distributions. The spectral energy distributions (SEDs) of neutrinos emitted from the entire region are flatter than those calculated under the single-zone approximation. In our model, the neutrino emission originating from cosmic rays advected with the outflow rather than the inflow predominates the SEDs. Such galactic nuclei can be significant sources of cosmic rays in those galaxies.}, archive = {J_ApJ}, author = {Tomohisa Kawashima and Katsuaki Asano}, doi = {10.3847/1538-4357/adee96}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {155}, shortjournal = {The Astrophys. J.}, title = {High-energy neutrino emission from a radiatively inefficient accretion flow with a three-dimensional general relativistic magnetohydrodynamic simulation}, volume = {989}, year = {2025}, }
• (2025). A closer look at an unusual ultradiffuse galaxy*. ApJ, 989(2), 154. (www)

  @article{ , abstract = {We present a spectroscopic study of the “Disco Ball” (SMDG0038365-064207), a rotationally supported, green-valley, ultradiffuse galaxy (UDG) with a nuclear star cluster, multiple stellar clusters, and active star-forming regions using data obtained with the Keck Cosmic Web Imager on the Keck II Telescope. We calculate that the galaxy hosts 31 ± 11 “globular” clusters (GCs). Kinematic measurements confirm rotation with a peak rotational velocity of at least 39 ± 9 km s −1 and a dynamical mass within the effective radius of at least 10 9.1 ± 0.2 M ⊙ . Our dynamical estimates of the halo mass are consistent with that obtained using the number of GCs and together suggest M h = 10 10.9 ± 0.2 M ⊙ . Our findings challenge two common assumptions: (1) clusters in some UDGs may be younger than generally assumed, and thus more luminous than standard GCs, affecting GC counts and the derived GC luminosity function in these UDGs, and (2) quiescent UDGs can be rotationally supported, making kinematic measurements viewing angle dependent in such cases. The Disco Ball, while unremarkable in mass, size, projected structural properties, or color, reveals surprising complexity, highlighting the need for detailed studies of more UDGs.}, archive = {J_ApJ}, author = {Donghyeon J. Khim and Dennis Zaritsky and Loraine Sandoval Ascencio and M. C. Cooper and Richard Donnerstein}, doi = {10.3847/1538-4357/adee99}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {154}, shortjournal = {The Astrophys. J.}, title = {A closer look at an unusual ultradiffuse galaxy*}, volume = {989}, year = {2025}, }
• (2025). Optical detection of the X-ray flash in the very fast nova v1674 her: Optical contribution of the irradiated accretion disk. ApJ, 989(2), 153. (www)

  @article{ , abstract = {V1674 Her is one of the fastest and brightest novae, characterized by dense optical photometry in the premaximum phase—a rise from g = 17 to 7 mag, over one-quarter of a day. We present a composite theoretical V light-curve model of its early rising phase, starting from a quiescent brightness of g = 19.2 mag. Our light-curve model consists of a hot and bright white dwarf (WD) and an irradiated accretion disk and companion star. We find that the earliest optical detection of an All Sky Automated Survey for Supernovae g -band brightness of g = 17.0 at t = 0.014 days from the onset of thermonuclear runaway can be explained with the irradiated accretion disk and companion star in the X-ray-flash phase of a 1.35 M ⊙ WD. This is the first detection in the optical of an X-ray-flash phase of a nova. Optically thick winds emerge from the WD photosphere at t = 0.04 days, and the optical flux is dominated by free–free emission from optically thin ejecta just outside the WD photosphere. Our free–free emission model V light curve reasonably reproduces the dense g light curve of Evryscope that spans from g = 14.8 (at 0.078 days) to g = 7.1 (at 0.279 days), including a sudden change of slope in the g light curve from a slow to a rapid rise at g = 14.3 on day 0.1. There is no indication of shocking power during the rising phase from g = 14.8 to 7.1.}, archive = {J_ApJ}, author = {Izumi Hachisu and Mariko Kato}, doi = {10.3847/1538-4357/adef0b}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {153}, shortjournal = {The Astrophys. J.}, title = {Optical detection of the X-ray flash in the very fast nova v1674 her: Optical contribution of the irradiated accretion disk}, volume = {989}, year = {2025}, }
• (2025). Alfvén waves from interchange reconnection at separators as a possible source of switchbacks. ApJ, 989(2), 152. (www)

  @article{ , abstract = {Parker Solar Probe has observed Alfvénic fluctuations of amplitude large enough to occasionally reverse the local magnetic field direction—a phenomenon known as a switchback. Some have attributed switchbacks to reconnection in the low corona between open and closed field lines, called interchange reconnection. This has not been investigated thoroughly enough to conclusively make the association. We make a small-scale magnetic model of a coronal hole to which PSP was briefly magnetically connected and show that no more than about 15% of the photosphere anchors magnetic field lines open to the heliosphere. The model’s field line mapping is characterized by a web of separatrices, an S-web, outlining ∼10 Mm cells reflecting the magnetic carpet. We find that PSP’s magnetic footpoint crossed S-web boundaries at a rate similar to encountering large magnetic field deflections. The model also reveals that interchange reconnection in the vicinity of an S-web separatrix generally occurs at a low-lying magnetic separator, and that such reconnection would launch a nonlinear Alfvén wave polarized within the separatrix surface. We use a thin flux tube model to infer that interchange reconnection at a low-lying separator can produce a wave with magnetic deflection as large as in a switchback. The average mass, momentum, and energy carried by a population of waves is estimated to be comparable to the solar wind itself. These findings appear to support the plausibility of interchange reconnection as a possible source of switchbacks.}, archive = {J_ApJ}, author = {Dana Longcope and Philip Klaassen}, doi = {10.3847/1538-4357/adf0ef}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {152}, shortjournal = {The Astrophys. J.}, title = {Alfvén waves from interchange reconnection at separators as a possible source of switchbacks}, volume = {989}, year = {2025}, }
• (2025). Can gamma-ray burst empirical correlations be used for population studies?. ApJ, 989(2), 151. (www)

  @article{ , abstract = {Only a small fraction of gamma-ray bursts (GRBs) have independent redshift measurements, which are essential for understanding their intrinsic properties. For this reason, empirical correlations of GRBs have often been touted as useful distance indicators, for both individual GRBs as well as population studies. Building upon our previous work, we test the ability of the Yonetoku, 3D Dainotti, and the {L}_{X}-{T}_{a}^{\ast }-{E}_{{\rm{iso}}} correlation to adequately constrain the GRB rate, Ψ GRB . Our analysis demonstrates that, even under idealized conditions that neglect substantial uncertainties, the derived redshift solutions cannot accurately constrain Ψ GRB , regardless of the intrinsic distribution’s characteristic width. We thus demonstrate unequivocally that—notwithstanding the questionable assumption of no selection biases—empirical GRB correlations alone cannot serve as reliable distance indicators at either the individual or population level.}, archive = {J_ApJ}, author = {Emre S. Yorgancioglu and Yun-Fei Du and Shu-Xu Yi and Shuang-Nan Zhang}, doi = {10.3847/1538-4357/adf20c}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {151}, shortjournal = {The Astrophys. J.}, title = {Can gamma-ray burst empirical correlations be used for population studies?}, volume = {989}, year = {2025}, }
• (2025). Sometimes they come back: Pulsations in a 0538–66 at 69 ms rediscovered with NICER. ApJ, 989(2), 150. (www)

  @article{ , abstract = {We report on Neutron Star Interior Composition Explorer (NICER) X-ray observations of the Be X-ray binary A 0538–66 located in the Large Magellanic Cloud. Fast pulsations (69 ms) in this source were discovered in 1980 during a bright outburst in which it reached a luminosity of ∼8 × 10 38 erg s −1 but were never reobserved since then. We clearly detected the pulsations at P = 69.3055 ± 0.0005 ms with a pulsed fraction of ∼20% during a short time interval (∼11 minutes) on 2023 January 9, when A 0538–66 had a luminosity of ∼8 × 10 36 erg s −1 (0.3–10 keV). The pulsations were not detected in other NICER observations (total exposure ∼162.7 ks), during which A 0538–66 had a similar or lower luminosity. On 2023 February 8–9 the source exhibited a strong variability, with short flares reaching ∼10 38 erg s −1 , but no periodic pulsations were detected. Assuming the magnetospheric radius lies within the corotation radius during pulsations, we estimate the neutron star magnetic field is below ∼2.7 × 10 10 G. This would make A 0538–66 the high-mass X-ray binary with the weakest known magnetic field. We discuss implications for magnetic field evolution in accreting pulsars and propose that, alternatively, A 0538–66 has a stronger magnetic field, and during the NICER detection, a centrifugal barrier may have been active while part of the plasma accumulated at the magnetosphere sporadically leaked through it via an instability mechanism, allowing accretion onto the polar caps.}, archive = {J_ApJ}, author = {Lorenzo Ducci and Sandro Mereghetti}, doi = {10.3847/1538-4357/adf338}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {150}, shortjournal = {The Astrophys. J.}, title = {Sometimes they come back: Pulsations in a 0538–66 at 69 ms rediscovered with NICER}, volume = {989}, year = {2025}, }
• (2025). Enhanced star formation and black hole accretion rates in galaxy mergers in IllustrisTNG50. ApJ, 989(2), 149. (www)

  @article{ , abstract = {Many theoretical and observational studies have suggested that galaxy mergers may trigger enhanced star formation or active galactic nucleus activity. We present an analysis of merging and nonmerging galaxies from 0.2 ≤ z ≤ 3 in the IllustrisTNG50 simulation. These galaxies encompass a range of masses ( M ⋆ > 10 8 M ⊙ ) and mass ratios (≥1:10) and multiple merger stages. We examine the effect that galaxy mergers have on star formation and black hole accretion rates in the TNG50 universe. We additionally investigate how galaxy and black hole mass, merger stage, merger mass ratio, and redshift affect these quantities. Mergers in our sample show excess specific star formation rates (sSFR) at z ≤ 3 and enhanced specific black hole accretion rates (sBHAR) at z ≲ 2. The difference between sSFRs and sBHARs in the merging sample compared to the nonmerging sample increases as redshift decreases. Additionally, we show that these enhancements persist for at least ∼1 Gyr after the merger event. Investigating how mergers behave in the TNG50 simulation throughout cosmic time enables both a better appreciation of the importance of spatial resolution in cosmological simulations and a better basis to understand our high- z Universe with observations from JWST.}, archive = {J_ApJ}, author = {Aimee L. Schechter and Shy Genel and Bryan Terrazas and Julia M. Comerford and Abigail Hartley and Rachel S. Somerville and Rebecca Nevin and Joseph Simon and Erica Nelson}, doi = {10.3847/1538-4357/ade791}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {149}, shortjournal = {The Astrophys. J.}, title = {Enhanced star formation and black hole accretion rates in galaxy mergers in IllustrisTNG50}, volume = {989}, year = {2025}, }
• (2025). Ion-rich acceleration during an eruptive flux rope event in a multiple null-point configuration. ApJ, 989(2), 148. (www)

  @article{ , abstract = {We report on the γ -ray emission above 100 MeV from the GOES M3.3 flare SOL2012-06-03. The hard X-ray (HXR) and microwave emissions have typical time profiles with a fast rise to a well-defined peak followed by a slower decay. The >100 MeV emission during the prompt phase displayed a double-peaked temporal structure with the first peak following the HXR and microwaves, and the second one, about 3 times stronger, occurring 17 ± 2 s later. The time profiles seem to indicate two separate acceleration mechanisms at work, where the second γ -ray peak reveals a potentially pure or at least largely dominant ion acceleration. The Atmospheric Imaging Assembly imaging shows a bright elliptical ribbon and a transient brightening in the northwestern (NW) region. Nonlinear force-free extrapolations at the time of the impulsive peaks show closed field lines connecting the NW region to the southeastern part of the ribbon, and the magnetic topology revealed clusters of nulls. These observations suggest a spine-and-fan geometry, and based on these observations, we interpret the second γ -ray peak as being due to the predominant acceleration of ions in a region with multiple null points. The >100 MeV emission from this flare also exhibits a delayed phase with an exponential decay of roughly 350 s. We find that the delayed emission is consistent with ions being trapped in a closed flux tube with gradual escape via their loss cone to the chromosphere.}, archive = {J_ApJ}, author = {Melissa Pesce-Rollins and Alexander MacKinnon and Karl-Ludwig Klein and Alexander J. B. Russell and Hugh Hudson and Alexander Warmuth and Thomas Wiegelmann and Sophie Masson and Clare Parnell and Nariaki V. Nitta and Nicola Omodei}, doi = {10.3847/1538-4357/adeb7f}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {148}, shortjournal = {The Astrophys. J.}, title = {Ion-rich acceleration during an eruptive flux rope event in a multiple null-point configuration}, volume = {989}, year = {2025}, }
• (2025). Metallicity gradients in modern cosmological simulations. i. tension between smooth stellar feedback models and observations. ApJ, 989(2), 147. (www)

  @article{ , abstract = {The metallicity of galaxies, and its variation with galactocentric radius, provides key insights into the formation histories of galaxies and the physical processes driving their evolution. In this work, we analyze the radial metallicity gradients of star-forming galaxies in the EAGLE, Illustris, IllustrisTNG, and SIMBA cosmological simulations across broad mass (10 8.0 M ⊙ ≤ M ⋆ ≲ 10 12.0 M ⊙ ) and redshift (0 ≤ z ≤ 8) ranges. We find that all simulations predict strong negative (i.e., radially decreasing) metallicity gradients at early cosmic times, likely due to their similar treatments of relatively smooth stellar feedback not providing sufficient mixing to quickly flatten gradients. The strongest redshift evolution occurs in galaxies with stellar masses of 10 10.0 –10 11.0 M ⊙ , while galaxies with stellar mass < 10 10 M ⊙ and >10 11 M ⊙ exhibit weaker redshift evolution. Our result of negative gradients at high redshift contrast with the many positive and flat gradients in the 1 < z < 4 observational literature. At z > 6, the negative gradients observed with JWST and the Atacama Large Millimeter/submillimeter Array are flatter than those in simulations, albeit with closer agreement than at lower redshift. Overall, we suggest that these smooth stellar feedback galaxy simulations may not sufficiently mix their metal content radially, and that either stronger stellar feedback or additional subgrid turbulent metal diffusion models may be required to better reproduce observed metallicity gradients.}, archive = {J_ApJ}, author = {Alex M. Garcia and Paul Torrey and Aniket Bhagwat and Ruby J. Wright and Qian-Hui Chen and Kathryn Grasha and Sophia Ridolfo and Z. S. Hemler and Arnab Sarkar and Priyanka Chakraborty and Erica J. Nelson and Ryan L. Sanders and Tiago Costa and Mark Vogelsberger and Lisa J. Kewley and Sara L. Ellison and Lars Hernquist}, doi = {10.3847/1538-4357/adea51}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {147}, shortjournal = {The Astrophys. J.}, title = {Metallicity gradients in modern cosmological simulations. i. tension between smooth stellar feedback models and observations}, volume = {989}, year = {2025}, }
• (2025). Optical and near-infrared spectroscopy of the outbursting comet 12P/Pons-brooks. ApJ, 989(2), 146. (www)

  @article{ , abstract = {We present optical and near-infrared (NIR) observations of the outbursting, Halley-type comet 12P/Pons-Brooks (12P). Three NIR spectra were obtained during two outbursts in 2023 October and November, with the 3 m Infrared Telescope Facility and the Palomar 200 inch Telescope, respectively. The NIR spectra exhibited absorption features at 1.5 and 2.0 μ m, consistent with the diagnostic absorption bands of water ice, superimposed on a red dust-scattering continuum. We find that the absorption bands and the red continuum can be well explained by micrometer-sized crystalline ice at 140–170 K, along with submicrometer-sized refractory grains (e.g., amorphous carbon). In addition, an optical spectrum was obtained with the Lijiang 2.4 m Telescope during the 2023 November outburst, which exhibited the emission bands of gaseous CN, C 3 , C 2 , and NH 2 . The C 3 /CN and C 2 /CN ratios suggest that 12P was “typical” in C 3 abundance but somewhat depleted in C 2 . The specific kinetic energy of the 2023 November outburst is estimated to be ∼8 × 10 3 J kg −1 , suggesting a likely triggering mechanism similar to 332P/Ikeya–Murakami and 17P/Holmes, i.e., the crystallization of amorphous water ice. A refractory-to-ice ratio of ∼1.7–3.2 is derived from the total mass loss of dust and gas, aligning with the lower-end estimates for 67P/Churyumov-Gerasimenko and 1P/Halley. This suggests either a less evolved nucleus or an outburst region enriched in icy materials relative to the bulk nucleus.}, archive = {J_ApJ}, author = {Ruining Zhao and Bin Yang and Michael S. P. Kelley and Silvia Protopapa and Aigen Li and Yang Huang and Jifeng Liu}, doi = {10.3847/1538-4357/adec8d}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {146}, shortjournal = {The Astrophys. J.}, title = {Optical and near-infrared spectroscopy of the outbursting comet 12P/Pons-brooks}, volume = {989}, year = {2025}, }
• (2025). Radiation spectrum of the photospheric emission for a turbulent relativistic jet. ApJ, 989(2), 145. (www)

  @article{ , abstract = {The prompt gamma rays of gamma-ray bursts (GRBs) may originate from the photosphere of a relativistic jet. However, only a few GRBs have been observed with evident blackbody-like emission, for example, GRB 090902B. It has been demonstrated that internal dissipation processes, such as magnetic reconnection, can occur within the relativistic jet and thereby drive violent turbulence in the dissipation region. In this paper, we study the photospheric emission of a jet with turbulence below its photosphere. Here, the turbulence is modeled phenomenologically under the assumption that the four-velocity of its eddies follows a Gaussian distribution in the jet’s comoving frame. It is found that the turbulence scatters photons to high energies and thus intensifies the emission in the high-energy regime. The corresponding distortion of the radiation field can be preserved if and only if the turbulence occurs in a region with incomplete photon–electron coupling. Consequently, the observed radiation spectrum can be reshaped into a Band-like spectrum.}, archive = {J_ApJ}, author = {Guo-Yu Li and Da-Bin Lin and Zhi-Lin Chen and En-Wei Liang}, doi = {10.3847/1538-4357/adf21e}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {145}, shortjournal = {The Astrophys. J.}, title = {Radiation spectrum of the photospheric emission for a turbulent relativistic jet}, volume = {989}, year = {2025}, }
• (2025). A unified volumetric Rate–Energy relation from magnetar radio bursts to fast radio bursts. ApJ, 989(2), 144. (www)

  @article{ , abstract = {Fast radio bursts (FRBs) are millisecond radio pulses with extremely high bright temperature. Their physical origin is still a mystery. The discovery of FRB 20020428 supports the idea that at least a portion of FRBs is generated by magnetars. However, FRB 20200428 and other radio bursts of SGR 1935+2154 are much less energetic than those of extragalactic FRBs. Thus, whether the progenitors of extragalactic FRBs are magnetars is still controversial. Here, we investigate the volumetric rates of radio bursts from SGR 1935+2154, nonrepeating FRBs, and FRB 20180916B using the uniform samples detected by the Canadian Hydrogen Intensity Mapping Experiment. We find that they share a similar relation between the volumetric rate R and the burst energy E , i.e., R ∝ E − γ with γ = 1.31 ± 0.13 from 10 29 to 10 42 erg. Our results support the hypothesis that both repeating and nonrepeating FRBs originate from magnetars.}, archive = {J_ApJ}, author = {Hao-Tian Lan and Shuang-Xi Yi and Fa-Yin Wang}, doi = {10.3847/1538-4357/adf3a8}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {144}, shortjournal = {The Astrophys. J.}, title = {A unified volumetric Rate–Energy relation from magnetar radio bursts to fast radio bursts}, volume = {989}, year = {2025}, }
• (2025). Fractal algorithm for multiple-lens analyses. ApJ, 989(2), 143. (www)

  @article{ , abstract = {A microlensing exoplanet search is a unique method for finding planets orbiting distant stars. However, in the past, the method used to analyze microlensing data could not deal with complex lens systems. The number of lenses was limited to three or less. Position calculations of images and their integration suffered from severe round-off errors because of singularities. We developed a new algorithm to calculate the light curves of multiple-lens systems. In this algorithm, fractal-like consecutive self-similar division (SSD) is used to find sparse images. SSD is also useful for integrating images to efficiently obtain magnifications. The new algorithm does not use root finding for the lens equation and is free from caustic singularities. There is no limit on the number of lenses that can be used with this algorithm. Compared to inverse-ray shooting, this method dramatically improves the computing time. The calculation can be adjusted to obtain either a high-precision final result or a high-speed quick result. Although this new algorithm was developed for a microlensing planet search, its application to quasar microlensing is also expected. This paper discusses problems in the modeling of a multiple-lens system and then presents the new algorithm in detail.}, archive = {J_ApJ}, author = {F. Abe}, doi = {10.3847/1538-4357/ade143}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {143}, shortjournal = {The Astrophys. J.}, title = {Fractal algorithm for multiple-lens analyses}, volume = {989}, year = {2025}, }
• (2025). Discovery of WINERED-HVS1: A metal-rich hypervelocity star candidate ejected from the galactic center. ApJ, 989(2), 142. (www)

  @article{ , abstract = {We report the discovery of a metal-rich red-giant star, WINERED-HVS1, which is a candidate for a hypervelocity star (HVS). Its past trajectory suggests that this star may have been ejected by the Galactic supermassive black hole (SMBH; Sgr A*), with a modest ejection velocity of at least 500 km s −1 . Since WINERED-HVS1 is gravitationally bound to the Milky Way and is not necessarily young, it is not an unambiguous HVS candidate from a kinematic perspective, unlike the previously confirmed A-type main-sequence HVS known as S5-HVS1. Therefore, the chemical characterization of this star is essential for understanding its origin. Through a spectroscopic follow-up observation with Magellan/WINERED, we determined its metallicity [{\rm{Fe}}/{\rm{H}}]=-0.14{7}_{-0.045}^{+0.046} , as well as the abundances of Na, Mg, Si, S, K, Ca, Ti, Cr, Ni, and Sr. The high-metallicity value suggests that this star was ejected from the Galactic center and is unlikely to be a halo star with a radial orbit. The abundance pattern of this star—including the patterns of [ α /Fe], [Mg/Fe], [Si/Mg], and [Ca/Mg]—is consistent with that of the nuclear star cluster surrounding the SMBH, further supporting our view. This discovery opens a new window to look through the Galactic center environment without the hindrance of dust extinction, by using the HVSs moving in the halo region where dust extinction is minimal.}, archive = {J_ApJ}, author = {Kohei Hattori and Daisuke Taniguchi and Takuji Tsujimoto and Noriyuki Matsunaga and Hiroaki Sameshima and Scarlet S. Elgueta and Shogo Otsubo}, doi = {10.3847/1538-4357/ade78a}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {142}, shortjournal = {The Astrophys. J.}, title = {Discovery of WINERED-HVS1: A metal-rich hypervelocity star candidate ejected from the galactic center}, volume = {989}, year = {2025}, }
• (2025). Atmospheric circulation of close-in extrasolar giant planets: The diabatic equivalent-barotropic model. ApJ, 989(2), 141. (www)

  @article{ , abstract = {We extend the description of equivalent-barotropic equations for exoplanets to the diabatic case—that is, with explicit heating and/or cooling representation, rather than with a stationary deflection of the bottom bounding surface. In the diabatic case, the equation for potential temperature (or entropy) is directly forced and cannot be decoupled from the equations for momentum and nonlinear pressure (the mass-like variable); hence, the isentropic surfaces do not remain coincident with material surfaces. Here the formalism is presented for an atmosphere with the Lamb vertical structure, as the formalism is substantially simplified while still remaining physically useful under the structure. The equations presented set the stage for accurate global simulations, which permit small-scale vortices, gravity waves, and fronts observed in current three-dimensional global simulations to be studied in detail.}, archive = {J_ApJ}, author = {Songyuan Wei and Jagat Kafle and James Y-K. Cho}, doi = {10.3847/1538-4357/ade9b9}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {141}, shortjournal = {The Astrophys. J.}, title = {Atmospheric circulation of close-in extrasolar giant planets: The diabatic equivalent-barotropic model}, volume = {989}, year = {2025}, }
• (2025). Energy-dependent transport of cosmic rays in the multiphase, dynamic interstellar medium. ApJ, 989(2), 140. (www)

  @article{ , abstract = {We investigate the transport of spectrally resolved cosmic-ray (CR) protons with kinetic energies between 1 and 100 GeV within the multiphase, dynamic interstellar medium (ISM), using a two-moment CR fluid solver applied to a TIGRESS MHD simulation with conditions similar to the solar neighborhood. Our CR transport prescription incorporates space- and momentum-dependent CR scattering coefficients σ = κ −1 , computed from the local balance between streaming-driven Alfvèn wave growth and damping processes. We find that advection combines with momentum-dependent diffusion to produce a CR distribution function f ( p ) ∝ p − γ with γ ≈ 4.6 that agrees with observations, steepened from an injected power-law slope γ inj = 4.3. The CR pressure is uniform in the highly diffusive, mostly neutral midplane region, but decreases exponentially in the ionized extraplanar region where scattering is efficient. To interpret these numerical results, we develop a two-zone analytic model that captures and links the two (physically and spatially) distinct regimes of CR transport in the multiphase, dynamic ISM. At low momenta, CR transport is dominated by gas advection, while at high momenta, both advection and diffusion contribute. At high momentum, the analytic prediction for the spectral slope approaches γ = (4/3) γ inj − 1, and the predicted scaling of grammage with momentum is X\propto {p}^{1-{\gamma }_{{\rm{inj}}}/3} , consistent with the simulations. These results support a physical picture in which CRs are confined within the neutral midplane by the surrounding ionized gas, with their escape regulated by both the CR scattering rate in the ionized extraplanar gas and the velocity and Alfvén speed of that gas, at effective speed {v}_{{\rm{c}},{\rm{eff}}}\approx (1/2){[{\kappa }_{\parallel }\,d(v+{v}_{{\rm{A}},{\rm{i}}})/dz]}^{1/2} .}, archive = {J_ApJ}, author = {Lucia Armillotta and Eve C. Ostriker and Nora B. Linzer}, doi = {10.3847/1538-4357/adea68}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {140}, shortjournal = {The Astrophys. J.}, title = {Energy-dependent transport of cosmic rays in the multiphase, dynamic interstellar medium}, volume = {989}, year = {2025}, }
• (2025). Ocean tides on asynchronously rotating planets orbiting low-mass stars. ApJ, 989(2), 139. (www)

  @article{ , abstract = {Planets in the liquid-water habitable zone of low-mass stars experience large tidal forces, 10 3 –10 4 times those on Earth, due to the small distance between the habitable zone and the host stars. Therefore, interior solid tides, ocean tides, and atmospheric tides on these planets could be much stronger than those on Earth, but little work has been done to explicitly simulate the ocean tides. Here, for the first time, we perform global ocean tide simulations and show that ocean tides on asynchronously rotating planets with large eccentricities can reach { \mathcal O }(1000)\,{\rm{m}} in height and { \mathcal O }(10)\,{\rm{m}}\,{{\rm{s}}}^{-1} in flow speed. Interactions between tide and bottom topography can induce large energy dissipation, \sim { \mathcal O }(100)\,{\rm{W}}\,{{\rm{m}}}^{-2} in the global mean. This tidal energy dissipation can strongly accelerate orbital evolution by 1–2 orders of magnitude. However, for planets with small eccentricities, the ocean tides are much weaker but still comparable to those on modern Earth. Our results suggest that ocean tides on eccentric planets orbiting low-mass stars are orders of magnitude more powerful than those on Earth and can dramatically influence surface geography and orbital evolution.}, archive = {J_ApJ}, author = {Jiaru Shi and Jun Yang and Dorian S. Abbot and Yonggang Liu and Wanying Kang and Yufeng Lin}, doi = {10.3847/1538-4357/adeb83}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {139}, shortjournal = {The Astrophys. J.}, title = {Ocean tides on asynchronously rotating planets orbiting low-mass stars}, volume = {989}, year = {2025}, }
• (2025). A first look at spatially resolved infrared supernova remnants in m33 with JWST. ApJ, 989(2), 138. (www)

  @article{ , abstract = {We present the first spatially resolved infrared images of supernova remnants (SNRs) in M33 with the unprecedented sensitivity and resolution of JWST. We analyze 40 SNRs in four JWST fields: two covering central and southern M33 with separate NIRCam (F335M, F444W) and MIRI (F560W, F2100W) observations, one ∼5 kpc-long radial strip observed with MIRI F770W, and one covering the giant H II region NGC 604 with multiple NIRCam and MIRI broad/narrowband filters. Of the 21 SNRs in the MIRI (F560W+F2100W) field, we found three clear detections (i.e., identical infrared and H α morphologies), and six partial-detections, implying a detection fraction of 43% in these bands. One of the SNRs in this field, L10-080, is a potential candidate for having freshly formed ejecta dust, based on its size and centrally concentrated 21 μ m emission. In contrast, only one SNR (out of 16) is detectable in the NIRCam F335M+F444W field. Two SNRs near NGC 604 have strong evidence of molecular (H 2 ) emission at 4.7 μ m, making them the farthest known SNRs with visible molecular shocks. Five SNRs have F770W observations, with the smaller younger objects showing tentative signs of emission, while the older, larger ones have voids. Multiwavelength data indicate that the clearly detected SNRs are also among the smallest, brightest at other wavelengths (H α , radio, and X-ray), have the broadest line widths (H α FWHM ∼ 250–350 km s −1 ), and the densest environments. No correlation between the JWST-detectability and local star formation history of the SNRs is apparent.}, archive = {J_ApJ}, author = {Sumit K. Sarbadhicary and Erik Rosolowsky and Adam K. Leroy and Thomas G. Williams and Eric W. Koch and Joshua Peltonen and Adam Smercina and Julianne J. Dalcanton and Simon C. O. Glover and Margaret Lazzarini and Ryan Chown and Jennifer Donovan Meyer and Karin Sandstrom and Benjamin F. Williams and Elizabeth Tarantino}, doi = {10.3847/1538-4357/adec7a}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {138}, shortjournal = {The Astrophys. J.}, title = {A first look at spatially resolved infrared supernova remnants in m33 with JWST}, volume = {989}, year = {2025}, }
• (2025). Resolving the origin of the unidentified TeV source HESS j1626-490 as a relic of the ancient cosmic-ray factory SNR g335.2+0.1. ApJ, 989(2), 137. (www)

  @article{ , abstract = {While decades of observations in the TeV gamma-ray band have revealed more than 200 sources with radio or X-ray counterparts, there remain dozens of unidentified TeV sources, which may provide crucial information of cosmic-ray (CR) accelerators. HESS J1626−490 is an unidentified TeV gamma-ray source but is expected to originate from CRs that escaped from the nearby supernova remnant (SNR) G335.2+0.1 and are interacting with dense interstellar clouds. To test this scenario, we scrutinize the properties of the SNR and search for nonthermal counterparts by analyzing observational data in the radio, X-ray, and GeV gamma-ray bands. From analysis of the H i and 12 CO ( J = 1–0) line data, we identify the cloud associated with the SNR and compare the morphologies of the cloud and the gamma-ray emission. The distance and age of the SNR are estimated to be 3.3 ± 0.6 kpc and ∼5 kyr, respectively. From X-ray and GeV gamma-ray data analyses, we find an extended GeV gamma-ray emission overlapping with the SNR and H.E.S.S. source regions but no X-ray emission. The location of the peak of the extended GeV emission changes from near the SNR at ≲1 GeV to the H.E.S.S. source at >10 GeV. We find a spectral hardening at ∼50 GeV, which is consistent with the existence of two components in the gamma-ray emission. We find that a combination of emission from the escaped CRs and the SNR itself can reproduce the observed broadband spectrum, on the assumption that the SNR has accelerated protons to ≳100 TeV in the past.}, archive = {J_ApJ}, author = {Tomohiko Oka and Wataru Ishizaki and Masaki Mori and Hidetoshi Sano and Hiromasa Suzuki and Takaaki Tanaka}, doi = {10.3847/1538-4357/adec80}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {137}, shortjournal = {The Astrophys. J.}, title = {Resolving the origin of the unidentified TeV source HESS j1626-490 as a relic of the ancient cosmic-ray factory SNR g335.2+0.1}, volume = {989}, year = {2025}, }
• (2025). Magellan spectroscopy of active galactic nuclei in low-mass galaxies: Scaling relations and a triple-peaked active galactic nucleus. ApJ, 989(2), 136. (www)

  @article{ , abstract = {In this work, we aim to further populate the low-mass regime of black hole (BH) scaling relations to better understand the formation and growth mechanisms of central supermassive BHs. We target six galaxies that have been previously identified as hosting active galactic nuclei (AGNs) based on optical spectroscopy from the Galaxy and Mass Assembly survey or the Sloan Digital Sky Survey with stellar masses reported to be M ⋆ < 5 × 10 9 M ⊙ . Using follow-up optical spectroscopy from the Magellan Echellette Spectrograph, we extract galaxy velocity dispersions ( σ ⋆ ) and estimate virial BH masses from broad H α emission. We find that the galaxies in our sample do not deviate significantly from either the M BH − σ * or M BH − M * scaling relations defined by higher-mass galaxies. Additionally, we identify one galaxy with triple-peaked [S II ], [N II ], H α , and H β emission lines. This spectral shape is not shared by [O III ] and, in fact, the [O III ] line appears to have distinct kinematics from the other emission lines. Incorporating the spatial distribution of the various emission lines, we find that the galaxy spectrum is consistent with a prominent central AGN driving an outflow, surrounded by an extended ring/disk of gas predominantly ionized by shocks and/or star formation. This work has implications for the demographics of BHs in low-mass galaxies and the role of AGN feedback.}, archive = {J_ApJ}, author = {Megan R. Sturm and Amy E. Reines and Jenny Greene and Sheyda Salehirad}, doi = {10.3847/1538-4357/aded92}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {136}, shortjournal = {The Astrophys. J.}, title = {Magellan spectroscopy of active galactic nuclei in low-mass galaxies: Scaling relations and a triple-peaked active galactic nucleus}, volume = {989}, year = {2025}, }
• (2025). Neutron star stability beyond the mass peak: Assessing the role of out-of-equilibrium perturbations. ApJ, 989(2), 135. (www)

  @article{ , abstract = {We investigate the radial stability of neutron stars under conditions where their composition may or may not remain in chemical equilibrium during oscillations. Using different equations of state that include nucleons, hyperons, and/or Δ resonances, we compute stellar configurations and examine their fundamental mode frequencies in two limiting scenarios. In one limit, nuclear reactions are fast enough to maintain chemical equilibrium throughout the pulsation, resulting in a lower adiabatic index, Γ EQ , and softer stellar responses. In the opposite limit, nuclear reactions are too slow to adjust particle abundances during oscillations, yielding a higher index, Γ FR , and stiffer stellar responses. We find that the equilibrium scenario triggers dynamic instability at the maximum-mass configuration, whereas the frozen composition scenario allows stable solutions to persist beyond this mass, extending the stable branch. This effect is modest for simpler equations of state but becomes increasingly pronounced for more complex compositions, where a complex interplay between the available degrees of freedom due to the emergence of new particle species and the values of the coupling constants leads to a significant disparity between Γ EQ and Γ FR . Realistic conditions, in which different nuclear reactions have distinct timescales, will place the effective Γ between these two extreme values, thereby limiting the length of the extended branch relative to the fully frozen limit studied here. We also explore astrophysical scenarios in which the extended branch may be populated and outline the multimessenger observations that could reveal its presence.}, archive = {J_ApJ}, author = {Martin O. Canullan-Pascual and Germán Lugones and Milva G. Orsaria and Ignacio F. Ranea-Sandoval}, doi = {10.3847/1538-4357/adf107}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {135}, shortjournal = {The Astrophys. J.}, title = {Neutron star stability beyond the mass peak: Assessing the role of out-of-equilibrium perturbations}, volume = {989}, year = {2025}, }
• (2025). Hidden binaries in star-forming regions. ApJ, 989(2), 134. (www)

  @article{ , abstract = {A significant fraction of, and possibly all, stars form in binary or multiple systems. For solar-mass stars in the Galactic field, the distribution of orbital separations is log-normal over 7 orders of magnitude, from 10 −2 to 10 5 au. In contrast, the separation distributions of systems in nearby star-forming regions paint a much more confusing picture. There appears to be an excess of systems in the separation range 10–1000 au, and recent high-resolution spectroscopic observations of close (<10 au) systems suggest a field-like distribution in some star-forming regions, but a possible excess with respect to the field in other regions. Furthermore, the resolution limit of numerical simulations of binary star formation is ∼1 au, and consequently, comparisons with the binary distributions in star-forming regions and in the field are restricted. In this paper, we demonstrate that these observational uncertainties and limitations in the simulations are potentially a much bigger problem than previously realised. We show that the log-normal separation distribution in the field can be reproduced by combining constituent binary populations whose initial separation distributions have a very different form from a log-normal. We also argue that the observed excess of binaries in the range 10–62 au in the Orion Nebula Cluster (ONC) compared to the Galactic field is not necessarily inconsistent with the field population, because the ONC is only one of many star-forming regions that populate the field. We propose that further observations of spectroscopic binaries in star-forming regions to probe and complete the <10 au parameter space are urgently needed.}, archive = {J_ApJ}, author = {Mary H. Rawcliffe and Nathan Griffiths-Janvier and Richard J. Parker}, doi = {10.3847/1538-4357/adf2ac}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {134}, shortjournal = {The Astrophys. J.}, title = {Hidden binaries in star-forming regions}, volume = {989}, year = {2025}, }
• (2025). Coronal mass Ejection–Induced sub-alfvénic solar wind: Key insights from parker solar probe. ApJ, 989(2), 133. (www)

  @article{ , abstract = {Since its eighth encounter, starting on 2022 April 28, Parker Solar Probe has consistently sampled the elusive sub-Alfvénic solar wind during each perihelion pass, offering unprecedented insights into these critical regions of the solar atmosphere. Here, we analyze sub-Alfvénic solar wind intervals longer than 10 minutes during the 10th encounter. The plasma sampled during these intervals shares some common features: considerable density drop relative to the surrounding plasma, very low plasma beta ( β p ), significantly reduced levels of magnetic field fluctuations, and high magnetic field variance anisotropy (transverse to the mean field). Interestingly, no switchbacks are observed in the analyzed sub-Alfvénic regions. We explore the potential role of coronal mass ejections (CMEs) in generating sub-Alfvénic wind regions. Remarkably, we find that every extended sub-Alfvénic wind interval during encounter 10 is linked to a CME. While all the observed sub-Alfvénic intervals are associated with CME wakes, the latter also has periods that are super-Alfvénic.}, archive = {J_ApJ}, author = {Vamsee Krishna Jagarlamudi and Carlos R. Braga and Nour E. Raouafi and Angelos Vourlidas}, doi = {10.3847/1538-4357/ada3d3}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {133}, shortjournal = {The Astrophys. J.}, title = {Coronal mass Ejection–Induced sub-alfvénic solar wind: Key insights from parker solar probe}, volume = {989}, year = {2025}, }
• (2025). MINDS: Detection of an inner gas disk caused by evaporating bodies around HD 172555. ApJ, 989(2), 132. (www)

  @article{ , abstract = {Mechanisms such as collisions of rocky bodies or cometary activity give rise to dusty debris disks. Debris disks trace the leftover building blocks of planets, and thus also planetary composition. HD 172555, a stellar twin of β Pic, hosts a debris disk thought to have resulted from a giant collision. It is known for its extreme mid-infrared silica dust feature, indicating a warm population of silica-rich grains in the asteroid belt (∼5 au), cold CO observed by Atacama Large Millimeter/submillimeter Array (ALMA), and small bodies evaporating as they approach close to the star. Our JWST Mid-InfraRed Instrument/Medium Resolution Spectroscopy (MIRI MRS) observations now reveal emission from an inner gaseous disk (<0.5 au) that arises from the evaporation of close-in material. For the first time in a debris disk, we detect neutral atomic chlorine and sulfur, as well as ionized nickel. We recovered the neutral sulfur line in ∼20 yr old Spitzer data, showing it is long-lived and stable. Ionized iron, previously seen only in β Pic, is also detected. All lines are broadened by Keplerian rotation, pinpointing the gas location. The HD 172555 system serves as a unique laboratory to study the composition of planetesimals, asteroids, and comets beyond the solar system. The comparison to β Pic reveals that the gas in HD 172555 is hotter, closer to the star, and poor in argon—suggesting it originates from evaporating rocky bodies near the star, while β Pic’s gas may trace volatile-rich bodies from larger separations.}, archive = {J_ApJ}, author = {Matthias Samland and Thomas Henning and Alessio Caratti o Garatti and Teresa Giannini and Jeroen Bouwman and Benoît Tabone and Aditya M. Arabhavi and Göran Olofsson and Manuel Güdel and Nicole Pawellek and Inga Kamp and L. B. F. M. Waters and Dmitry Semenov and Ewine F. van Dishoeck and Olivier Absil and David Barrado and Anthony Boccaletti and Valentin Christiaens and Danny Gasman and Sierra L. Grant and Hyerin Jang and Till Kaeufer and Jayatee Kanwar and Giulia Perotti and Kamber Schwarz and Milou Temmink}, doi = {10.3847/1538-4357/ade2db}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {132}, shortjournal = {The Astrophys. J.}, title = {MINDS: Detection of an inner gas disk caused by evaporating bodies around HD 172555}, volume = {989}, year = {2025}, }
• (2025). Parsec-scale SiO emission in the galactic center. ApJ, 989(2), 131. (www)

  @article{ , abstract = {The central 5 pc of our Galactic center is rich in various molecular tracers. The region is observed to be hot, highly ionized, and volatile, resulting in complex chemistry and kinematics. Countless molecular observations of the central region orbiting the central supermassive black hole Sgr A * have revealed a stable grouping of clouds with a disklike structure known as the circumnuclear disk (CND) orbiting Sgr A * between 1.5 and 3 pc. The CND houses the densest population of gas outside the ionized streams in the minispiral falling onto Sgr A * . However, the small-scale kinematics of the clouds and gas are poorly understood in this region. In this paper, we report single-dish SiO (1–0) observations of the central 5 pc surrounding Sgr A * taken with the Green Bank Telescope. Most of the SiO (1–0) traces the Southern Streamer and Sgr A East—neither of which are associated with the CND. However, one region in the CND, known as the Northeast (NE) Arm, shows high-intensity SiO emission unlike in the rest of the CND, indicating the NE Arm as a candidate region of either cloud–cloud collision or early star formation. Further high-resolution observations of the region are needed to distinguish between the two scenarios.}, archive = {J_ApJ}, author = {N. Wenner and C. J. Chandler and J. M. Michail and M. Gorski and J. Braatz}, doi = {10.3847/1538-4357/adeb75}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {131}, shortjournal = {The Astrophys. J.}, title = {Parsec-scale SiO emission in the galactic center}, volume = {989}, year = {2025}, }
• (2025). Constraining the faint-end slope of the fast radio burst energy function using CHIME/FRB catalog-1 and local volume galaxies. ApJ, 989(2), 130. (www)

  @article{ , abstract = {Despite hundreds of detected fast radio bursts (FRBs), the faint-end slope ( γ ) of their energy distribution remains poorly constrained, hindering understanding of whether bright, cosmological FRBs and faint, Galactic magnetar SGR 1935+2154-like bursts share a common origin. In this study, we constrain this faint-end slope, modeled with a Schechter-like distribution, by searching for potential associations between bursts from the CHIME/FRB Catalog-1 and galaxies in the Local Volume. We crossmatched CHIME/FRB Catalog-1 FRBs with 495 Local Volume galaxies within 21 Mpc, identified from the HECATE catalog, and found no associations. Assuming the FRB energy function extends to ∼3 × 10 34 erg—the energy of the Galactic magnetar burst from SGR 1935+2154—this null result constrains γ to be <2.3 (95% confidence upper limit), representing the first empirical estimate for extragalactic FRBs at such low energies. This finding supports the hypothesis that the FRB population is dominated by bright, likely cosmological bursts with a relatively flat energy distribution ( γ < 2.5). However, the constraint weakens if higher-energy thresholds are assumed. A flatter energy function is consistent with the observed anticorrelation between FRB dispersion measure and fluence, as seen across various observational bands. While the contribution of low-energy bursts, such as those from the Galactic magnetar SGR 1935+2154, appears minimal, our results suggest that normal magnetars like SGR 1935+2154 could dominate the FRB population if their burst rates and energies scale with age and magnetic field. The upcoming CHIME/FRB Catalog-2 data and targeted nearby galaxy surveys will further refine these constraints, offering critical insight into whether FRBs arise from a single population or diverse origins.}, archive = {J_ApJ}, author = {Mohit Bhardwaj and Victoria M. Kaspi and K. W. Masui and B. M. Gaensler and Adaeze L. Ibik and Mawson W. Sammons}, doi = {10.3847/1538-4357/aded17}, journal = {The Astrophysical Journal}, month = {8}, number = {2}, pages = {130}, shortjournal = {The Astrophys. J.}, title = {Constraining the faint-end slope of the fast radio burst energy function using CHIME/FRB catalog-1 and local volume galaxies}, volume = {989}, year = {2025}, }
• (2025). Nonlinearity of 3 minute slow magnetoacoustic waves in the sunspot umbral atmosphere. ApJ, 989(1), 129. (www)

  @article{ , abstract = {Slow magnetoacoustic waves with a 3 minute period are upward-propagating waves traveling through the density-stratified umbral atmosphere. The decreasing density causes their amplitude to increase, developing into nonlinear waves through steepening and eventually forming shocks. To investigate the vertical evolution of this wave nonlinearity, we utilized multiwavelength data from the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory, covering from the photosphere to the lower corona across 20 active regions. The steepening of the wave profile leads to the generation of higher harmonics. We quantify this using a nonlinearity index (NI), defined as the ratio of the amplitude of the second harmonic to the fundamental obtained using wavelet analysis. We find a characteristic pattern: nonlinearity increases from the photosphere through the lower chromosphere, peaking near the AIA 1700 Å formation height, and decreases at higher altitudes, notably in the AIA 304 Å channel. This trend indicates progressive wave steepening and subsequent energy dissipation before reaching the formation of AIA 304 Å, consistent with shock formation in the lower atmosphere. An additional rise in NI is observed at the AIA 131 Å channel, followed by a decline in AIA 171 Å, suggesting a second phase of wave nonlinearity evolution in the lower corona. Based on the NI profile and the formation heights of these channels, we conjecture that nonlinear wave processes are most prominent between the AIA 1700 Å and AIA 304 Å formation layers and again between AIA 131 Å and AIA 171 Å.}, archive = {J_ApJ}, author = {Y. Sanjay and S. Krishna Prasad and Robert Sych and P. S. Rawat}, doi = {10.3847/1538-4357/adef34}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {129}, shortjournal = {The Astrophys. J.}, title = {Nonlinearity of 3 minute slow magnetoacoustic waves in the sunspot umbral atmosphere}, volume = {989}, year = {2025}, }
• (2025). JVLA and VLBA study of the merging cool core CHIPS 1911+4455 at z ∼ 0.5 radio emission from an infant active galactic nucleus and from a rapidly star-forming brightest cluster galaxy. ApJ, 989(1), 128. (www)

  @article{ , abstract = {Recent studies of galaxy clusters found peculiar cases at the boundary between noncool core and cool core systems. While unusual, these objects can help us understand the evolution of the most massive clusters. We investigated the role of active galactic nucleus (AGN) feedback in the starburst brightest cluster galaxy (BCG) of the merging cool core cluster CHIPS 1911+4455 ( z = 0.485). We conducted new multifrequency (0.3–5 GHz) Very Long Baseline Array (VLBA) and Jansky Very Large Array (JVLA) observations of CHIPS 1911+4455 across a wide range of scales (0.01–20 kpc). Our analysis reveals that the AGN in the BCG has recently awakened, showing a compact core with symmetric, ∼30 pc long jets in VLBA data. The onset of the AGN may be linked to the enhanced cooling of the hot gas found in a previous study. At larger scales (10 kpc), faint radio whiskers extending to the south show a striking alignment with star-forming knots and are thus interpreted as synchrotron-emitting regions associated with the starburst BCG. The implied radio star formation rate of 100–155 M ⊙ yr −1 agrees with the optical/infrared one (140−190 M ⊙ yr −1 ). Our JVLA and VLBA radio study, informed by previous X-ray/optical/millimeter works, indicates that CHIPS 1911+4455 represents a transitional phase in cluster evolution, where the AGN in the central galaxy has just begun to respond to copious hot gas cooling.}, archive = {J_ApJ}, author = {Francesco Ubertosi and Myriam Gitti and Pasquale Temi and Ewan O’Sullivan and Valeria Olivares and Gerrit Schellenberger and Fabrizio Brighenti and Marcello Giroletti}, doi = {10.3847/1538-4357/adf19c}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {128}, shortjournal = {The Astrophys. J.}, title = {JVLA and VLBA study of the merging cool core CHIPS 1911+4455 at z ∼ 0.5 radio emission from an infant active galactic nucleus and from a rapidly star-forming brightest cluster galaxy}, volume = {989}, year = {2025}, }
• (2025). PSR j1735–0243: A pulsar with three cone components exhibiting mode-changing behavior. ApJ, 989(1), 127. (www)

  @article{ , abstract = {We have carried out a detailed analysis of PSR J1735−0243 with the Five-hundred-meter Aperture Spherical radio Telescope at 1250 MHz. We found that this pulsar shows obvious mode changing, with approximately 82% in the normal mode and approximately 18% in the abnormal mode. The two modes differ not only in their integrated pulse profiles but also in their polarization properties. Further analyses suggest that the emission from the normal mode may originate from a higher height than the abnormal mode. Additionally, we found that the radio emission beam consists of four emission components, including a core component and three cone components. The tertiary cone component, which has the highest emission height, is present in both emission modes. Finally, the results shown that the radio emission of PSR J1735−0243 may have been generated in the core gap region.}, archive = {J_ApJ}, author = {Xin Xu and Qijun Zhi and Jie Tian and Jiguang Lu and Peng Jiang and Dai Shi and Shijun Dang and Guojun Qiao}, doi = {10.3847/1538-4357/adf1a1}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {127}, shortjournal = {The Astrophys. J.}, title = {PSR j1735–0243: A pulsar with three cone components exhibiting mode-changing behavior}, volume = {989}, year = {2025}, }
• (2025). Tera-hertz counterparts to fast radio bursts from coherent cherenkov radiation by tilted bunches. ApJ, 989(1), 126. (www)

  @article{ , abstract = {Fast radio bursts (FRBs) are millisecond-duration extragalactic transients characterized by ultrahigh brightness temperatures, suggesting coherent emission mechanisms in extreme astrophysical processes. In this paper, we extend the bunched coherent Cherenkov radiation (CChR) framework by incorporating bunch inclination and geometric configuration parameters, enabling it to more rigorously model FRB emission and tera-Hertz (THz) emission from magnetars. When relativistic bunches are injected into the magnetized plasma of a magnetar’s magnetosphere at the Cherenkov angle, their emitted waves achieve phase coherence through constructive interference. Furthermore, the three-dimensional geometry of the bunches plays a crucial role in influencing the coherence of the radiation. Within the framework of CChR, we predict the existence of THz emission counterparts associated with FRBs and explain the observed characteristics of the THz-emitting magnetar SGR J1745-2900. Detections of such counterparts by upgraded millimeter telescopes (e.g., Atacama Large Millimeter/submillimeter Array, IRAM) would be expected to provide new insights into the potential physical connection between FRBs and magnetars.}, archive = {J_ApJ}, author = {Ze-Nan Liu and Wei-Yang Wang and Yu-Chen Huang and Zi-Gao Dai}, doi = {10.3847/1538-4357/adea76}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {126}, shortjournal = {The Astrophys. J.}, title = {Tera-hertz counterparts to fast radio bursts from coherent cherenkov radiation by tilted bunches}, volume = {989}, year = {2025}, }
• (2025). Modeling the multiwavelength emission of 3C 279 during the 14 yr fermi-LAT era. ApJ, 989(1), 125. (www)

  @article{ , abstract = {We report the results of our long-term multiwavelength spectral energy distribution (SED) study on the flat-spectrum radio quasar 3C 279 during the ∼14 yr (2008–2022) Fermi-Large Area Telescope (LAT) observing period. The Fermi-LAT data were complemented with data in other wave bands obtained from the Swift-X-Ray Telescope (XRT)/UVOT, the Whole Earth Blazar Telescope, along with other optical and radio data from several observatories. Different activity states were identified from the weekly binned γ -ray light curve, and it was possible to create 168 high-quality and quasi-simultaneous broadband SEDs. We modeled the SEDs using a one-zone leptonic scenario, including the emission region outside the broad-line region (BLR), involving synchrotron, synchrotron self-Compton, and external Compton mechanisms. Such extensive broadband modeling is essential for constraining the underlying multiwavelength radiative mechanisms in the 3C 279 jet and permits the estimation of the physical parameters and exploration of their evolution in time. Our SED modeling study suggests that the increase in the Doppler beaming factor, along with the variation of the emitting electrons, is the cause for the flares in this source. The multiwavelength emission of 3C 279 was found to be well explained by the scenario in which the emission region is outside the BLR at a distance of ∼6.42 × 10 3 R S . However, for two of the very bright γ -ray states, the emission region was found to be close to the outer boundary of the BLR at a distance of ∼1.28 × 10 3 R S from the central black hole.}, archive = {J_ApJ}, author = {Krishna Mohana A and Alok C. Gupta and Junhui Fan and Narek Sahakyan and Claudia M. Raiteri and Lang Cui and Anne Lähteenmäki and Mark Gurwell and Merja Tornikoski and Massimo Villata}, doi = {10.3847/1538-4357/adec77}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {125}, shortjournal = {The Astrophys. J.}, title = {Modeling the multiwavelength emission of 3C 279 during the 14 yr fermi-LAT era}, volume = {989}, year = {2025}, }
• (2025). Constraints on fast radio burst population from the first CHIME/FRB catalog with the hierarchical bayesian inference. ApJ, 989(1), 124. (www)

  @article{ , abstract = {Fast radio bursts (FRBs) have emerged as one of the most dynamic areas of research in astronomy and cosmology. Despite increasing number of FRBs having been reported, the exact origin of FRBs remains elusive. Investigating the intrinsic redshift distributions of FRBs could provide valuable insights into their possible origins and enhance the power of FRBs as a cosmological probe. In this paper, we propose a hierarchical Bayesian inference approach combining with several viable models to investigate the redshift distribution of the Canadian Hydrogen Intensity Mapping Experiment/FRB catalog 1. By utilizing this method, we aim to uncover the underlying patterns and characteristics of the FRB population, i.e., the intrinsic redshift distribution of FRB. Taking uncertainties within the observational data and selection effects into consideration, we found that the redshift distribution of FRBs is significantly delayed with respect to that of the star formation history.}, archive = {J_ApJ}, author = {Huan Zhou and Zhengxiang Li and Zong-Hong Zhu}, doi = {10.3847/1538-4357/adee15}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {124}, shortjournal = {The Astrophys. J.}, title = {Constraints on fast radio burst population from the first CHIME/FRB catalog with the hierarchical bayesian inference}, volume = {989}, year = {2025}, }
• (2025). The impact of stellar rotations and binaries on the shape of upper main sequence near turnoff in open cluster NGC 6067. ApJ, 989(1), 123. (www)

  @article{ , abstract = {We present the analysis of the extended main-sequence turnoff (eMSTO) in the open cluster NGC 6067. We derive the projected rotational velocity, v sin i , of the stars belonging to the eMSTO region of the main sequence (MS) utilizing Gaia-ESO spectra. Our results reveal a positive correlation between v sin i and the color of eMSTO stars, where fast-rotating stars predominantly occupy the red part of the MS while slow-rotating ones prefer a bluer side of the MS. The gravity-darkening effect might be a reason for this correlation. We find that most of the close binaries present in the eMSTO population would be slow-rotating due to the tidal-locking phenomenon. We identify four double-lined spectroscopic binaries (SB2) featuring slow-rotating companions, further supporting this tidal-locking hypothesis. However, the spatial distribution and the cumulative radial distribution indicate a higher concentration of red eMSTO stars in the cluster’s central region than their bluer counterparts. This suggests that tidal locking is less likely to be the cause of the observed spread in rotation rates among eMSTO stars. Instead, we propose that star–disk interactions during the pre-main-sequence phase might have played a crucial role in spreading the rotation rates of stars, leading to the eMSTO phenomenon in NGC 6067.}, archive = {J_ApJ}, author = {Jayanand Maurya and Yu Zhang and Sebastian Kamann and Hubiao Niu and Yves Frémat and Kaixiang Lang and Y. C. Joshi and M. R. Samal and Peter De Cat and Ali Esamdin}, doi = {10.3847/1538-4357/adef40}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {123}, shortjournal = {The Astrophys. J.}, title = {The impact of stellar rotations and binaries on the shape of upper main sequence near turnoff in open cluster NGC 6067}, volume = {989}, year = {2025}, }
• (2025). The fate of EMRI-IMRI pairs in active galactic nucleus accretion disks: Hydrodynamical and three-body simulations. ApJ, 989(1), 122. (www)

  @article{ , abstract = {Extreme-mass-ratio inspirals (EMRIs) and intermediate-mass-ratio inspirals (IMRIs) are important gravitational wave (GW) sources for the Laser Interferometer Space Antenna. It has recently been suggested that EMRIs and IMRIs can both form in the accretion disk of an active galactic nucleus (AGN). Considering the likely encounter between a stellar-mass black hole (sBH) and an intermediate-mass black hole (IMBH) during migration in the AGN disk, P. Peng & X. Chen (Paper I) showed that a gap-opening IMBH can drive a surrounding sBH to migrate synchronously. In this work, we extend the study in Paper I with a more sophisticated model. We first use 3D hydrodynamical simulations to study the coevolution of the disk and the migration of an sBH in the vicinity of an IMBH. We find that the gaseous torque, together with the tidal torque exerted by the IMBH, can drive synchronized migration until ∼10 Schwarzschild radii from the central supermassive black hole. We further use a relativistic three-body code to study the final fate of the sBH in the GW-dominated regime. We find that the sBH can be either captured or kicked out by the IMBH, which will result in either two subsequent IMRIs or an EMRI followed by an IMRI. These events will bring rich information about the formation and evolution of sBHs and IMBHs in AGNs.}, archive = {J_ApJ}, author = {Peng Peng and Alessia Franchini and Matteo Bonetti and Alberto Sesana and Xian Chen}, doi = {10.3847/1538-4357/adef42}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {122}, shortjournal = {The Astrophys. J.}, title = {The fate of EMRI-IMRI pairs in active galactic nucleus accretion disks: Hydrodynamical and three-body simulations}, volume = {989}, year = {2025}, }
• (2025). Bar-driven streaming motions mimic a massive bulge in the inner milky way. ApJ, 989(1), 121. (www)

  @article{ , abstract = {The circular speed curve of the Milky Way provides a key constraint on its mass distribution, reflecting the axisymmetric component of the gravitational potential. This is especially critical in the inner Galaxy ( R ≲ 4 kpc), where nonaxisymmetric structures, such as the stellar bar and nuclear stellar disk, strongly influence dynamics. However, significant discrepancies remain between circular speed curves inferred from stellar dynamical modeling and those derived from the terminal-velocity method applied to gas kinematics. To investigate this, we perform three-dimensional hydrodynamic simulations including cooling, heating, star formation, and feedback, under a realistic gravitational potential derived from stellar dynamical models calibrated to observational data. This potential includes the Galactic bar, stellar disks, dark matter halo, nuclear stellar disk, and nuclear star cluster. We generate synthetic longitude–velocity diagrams and apply the terminal-velocity method to derive circular speeds. The simulated gas reproduces the observed terminal-velocity envelope, including a steep inner rise. We find this feature arises from bar-driven noncircular motions, which cause the terminal-velocity method to overestimate circular speeds by up to a factor of 2 at R ∼ 0.4 kpc, and enclosed mass by up to a factor of 4. These results suggest that inner gas-based rotation curves can significantly overestimate central mass concentrations. The steep inner rise in gas-derived circular speeds does not require a massive classical bulge but can be explained by bar-induced streaming motions. Rather than proposing a new mechanism, our study provides a clear, Milky Way–specific demonstration of this effect, emphasizing the importance of dynamical modeling that explicitly includes noncircular motions for accurate mass inference in the inner Milky Way.}, archive = {J_ApJ}, author = {Junichi Baba}, doi = {10.3847/1538-4357/adf2a3}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {121}, shortjournal = {The Astrophys. J.}, title = {Bar-driven streaming motions mimic a massive bulge in the inner milky way}, volume = {989}, year = {2025}, }
• (2025). Uncalibrated cosmic standards as a robust test on late-time cosmological models. ApJ, 989(1), 120. (www)

  @article{ , abstract = {We present an assumption-minimized framework for testing late-time cosmological models using uncalibrated cosmic standards (UCS)—including standard rulers and standard candles—without relying on absolute calibrations. The method exploits a tight, model-insensitive correlation between the sound horizons at recombination and the drag epoch. By avoiding dependence on prerecombination physics and the amplitude of the cosmic microwave background (CMB) power spectra, the UCS framework reduces potential early-Universe biases while retaining much of the constraining power of full analyses. Applying UCS to the recent dynamical dark energy study that reported deviations from ΛCDM, we find the constraints shift systematically toward the ΛCDM case. If this shift is physical, it may result from the omission of some prerecombination physical processes that influence the scale dependence of the CMB spectra. We also observe a mild tension between uncalibrated standard rulers and candles, which can be largely mitigated by introducing a redshift-dependent magnitude bias in the Type Ia supernovae data. Our results highlight the importance of isolating postrecombination observables for testing late-time models in the era of precision cosmology, positioning UCS analysis as a robust framework for upcoming galaxy surveys.}, archive = {J_ApJ}, author = {Yihao Wang and Weikang Lin}, doi = {10.3847/1538-4357/adf336}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {120}, shortjournal = {The Astrophys. J.}, title = {Uncalibrated cosmic standards as a robust test on late-time cosmological models}, volume = {989}, year = {2025}, }
• (2025). Frequency and abundance of binary supermassive black holes from optical variability surveys (Fabulovs): Hubble space telescope imaging of radial-velocity-selected binary candidates. ApJ, 989(1), 119. (www)

  @article{ , abstract = {Subparsec binary supermassive black holes (BSBHs) should be common from galaxy mergers, yet direct evidence has been elusive. We present Hubble Space Telescope (HST)/WFC3IR F160W imaging for a sample of eight candidate subparsec BSBHs at redshifts z ∼ 0.1–0.5, as well as cross-comparison with a sample of ordinary quasars with archival HST/WFC3 IR F160W images. These eight candidate subparsec BSBHs were identified from multiepoch spectroscopic surveys of quasars (including both typical quasars and those with single-peaked velocity-offset broad lines), whose broad H β lines are significantly offset (by ≳ a few hundred kilometers per second) from the systemic redshifts. We directly test the prediction that the host galaxies of BSBHs would have a higher fraction of disturbed morphologies and younger stellar bulges from recent interactions than those of control quasars. After careful subtraction of the central quasar light, our candidate BSBH hosts show a statistically undifferentiated distribution of host asymmetry, indicative of a similar fraction of recent mergers. While a significantly larger sample is needed to place this result on a much firmer statistical ground, it opens questions as to the timescale differences between galaxy merger and BSBH formation, or the efficacy of the radial-velocity-shift-based selection of subparsec BSBH candidates.}, archive = {J_ApJ}, author = {Liam Nolan and Ming-Yang Zhuang and Xin Liu and Yu-Ching Chen and Shreya Majumdar and Junyao Li and Yue Shen}, doi = {10.3847/1538-4357/adec95}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {119}, shortjournal = {The Astrophys. J.}, title = {Frequency and abundance of binary supermassive black holes from optical variability surveys (Fabulovs): Hubble space telescope imaging of radial-velocity-selected binary candidates}, volume = {989}, year = {2025}, }
• (2025). A multispacecraft analysis and modeling of type III radio burst exciter deceleration in inhomogeneous heliospheric plasma. ApJ, 989(1), 118. (www)

  @article{ , abstract = {Electron beams accelerated in solar flares and escaping from the Sun along open magnetic field lines can trigger intense radio emissions known as type III solar radio bursts. Utilizing observations by Parker Solar Probe (PSP), STEREO-A, Solar Orbiter, and Wind spacecraft, the speeds and accelerations of type III exciters are derived for simple and isolated type III solar bursts. For the first time, simultaneous four spacecraft observations allow us to determine positions and correct the resulting velocities and accelerations for the location between the spacecraft and the apparent source. We observe velocities and acceleration to change as u ( r ) ∝ r −0.37 ± 0.14 and a ( r ) ∝ r −1.71 ± 0.20 with radial distance from the Sun r . To explain the electron beam deceleration, we develop a simple gas-dynamic description of the electron beam moving through plasma with monotonically decreasing density. The model predicts that the beam velocity decreases as u ( f ) ∝ f 1/4 ( r ), so the acceleration changes ∝ r −1.58 (and speed as ∝ r −0.29 ) for the plasma density profile n ( r ) ∝ r −2.3 . The deceleration is consistent with the average observation values corrected for the type III source locations. Intriguingly, the observations also show differences in velocity and acceleration of the same type III observed by different spacecraft. We suggest the difference could be related to the additional time delay caused by radio-wave scattering between the spacecraft and the source.}, archive = {J_ApJ}, author = {Francesco Azzollini and Eduard P. Kontar}, doi = {10.3847/1538-4357/adee22}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {118}, shortjournal = {The Astrophys. J.}, title = {A multispacecraft analysis and modeling of type III radio burst exciter deceleration in inhomogeneous heliospheric plasma}, volume = {989}, year = {2025}, }
• (2025). Semianalytical model for the dynamical evolution of planetary systems. II. application to systems formed by a planet formation model. ApJ, 989(1), 117. (www)

  @article{ , abstract = {The standard formation model of close-in low-mass planets involves efficient inward migration followed by growth through giant impacts after the protoplanetary gas disk disperses. While detailed N -body simulations have enhanced our understanding, their high computational cost limits statistical comparisons with observations. In our previous work, we introduced a semianalytical model to track the dynamical evolution of multiple planets through gravitational scattering and giant impacts after the gas disk dispersal. Although this model successfully reproduced N -body simulation results under various initial conditions, our validation was still limited to cases with compact, equally spaced planetary systems. In this paper, we improve our model to handle more diverse planetary systems characterized by broader variations in planetary masses, semimajor axes, and orbital separations and validate it against recent planet population synthesis results. Our enhanced model accurately reproduces the mass distribution and orbital architectures of the final planetary systems. Thus, we confirm that the model can predict the outcomes of postgas disk dynamical evolution across a wide range of planetary system architectures, which is crucial for reducing the computational cost of planet formation simulations.}, archive = {J_ApJ}, author = {Tadahiro Kimura and Eiichiro Kokubo and Yuji Matsumoto and Christoph Mordasini and Masahiro Ikoma}, doi = {10.3847/1538-4357/adef15}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {117}, shortjournal = {The Astrophys. J.}, title = {Semianalytical model for the dynamical evolution of planetary systems. II. application to systems formed by a planet formation model}, volume = {989}, year = {2025}, }
• (2025). Ultradense dark matter halos with poisson noise from stellar-mass primordial black holes. ApJ, 989(1), 116. (www)

  @article{ , abstract = {In this work, we investigate the impact of Poisson noise from stellar-mass primordial black holes (PBHs) on the formation of ultradense dark matter halos (UDMHs). Our findings reveal that the discrete spatial distribution of PBHs significantly enhances small-scale density fluctuations, particularly for massive stellar-mass PBHs. Our results indicate that the modified power spectrum, incorporating both adiabatic and isocurvature contributions from PBH-induced Poisson noise, strongly depends on PBH mass and fraction. Specifically, increasing PBH mass shifts the differential mass function of UDMHs toward higher masses, while variations in the suppression parameter n modulate the efficiency of UDMH formation at small scales. For lower values of n , our findings show a significant boost in UDMH abundance, favoring multicomponent dark matter scenarios. Conversely, at higher values of n , the predicted UDMH distributions align more closely with single-component models dominated by stellar-mass PBHs. Furthermore, our analysis demonstrates that more realistic halo mass functions, which account for angular momentum and dynamical friction, consistently predict higher UDMH abundances compared to the traditional Press–Schechter formalism.}, archive = {J_ApJ}, author = {Saeed Fakhry and Javad T. Firouzjaee}, doi = {10.3847/1538-4357/adf21a}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {116}, shortjournal = {The Astrophys. J.}, title = {Ultradense dark matter halos with poisson noise from stellar-mass primordial black holes}, volume = {989}, year = {2025}, }
• (2025). ALMA lensing cluster survey: Physical characterization of near-infrared-dark intrinsically faint ALMA sources at z = 2–4. ApJ, 989(1), 115. (www)

  @article{ , abstract = {We present results from Atacama Large Millimeter/submillimeter Array (ALMA) spectral line-scan observations at 3 mm and 2 mm bands of three near-infrared-dark (NIR-dark) galaxies behind two massive lensing clusters MACS J0417.5-1154 and RXC J0032.1+1808. Each of these three sources is a (sub)millimeter faint (delensed S 1.2 mm < 1 mJy) triply lensed system originally discovered in the ALMA Lensing Cluster Survey. We have successfully detected CO and [C i ] emission lines and confirmed that their spectroscopic redshifts are z = 3.652, 2.391, and 2.985. By utilizing a rich multiwavelength data set, we find that the NIR-dark galaxies are located on the star formation main sequence in the intrinsic stellar mass range of log ( M * / M ⊙ ) = 9.8–10.4, which is about 1 order of magnitude lower than that of typical submillimeter galaxies (SMGs). These NIR-dark galaxies show a variety in gas depletion times and spatial extent of dust emission. One of the three is a normal star-forming galaxy with gas depletion time consistent with a scaling relation, and its infrared surface brightness is an order of magnitude smaller than that of typical SMGs. Since this galaxy has an elongated axis ratio of ∼0.17, we argue that normal star-forming galaxies in an edge-on configuration can be heavily dust-obscured. This implies that existing deep WFC3/F160W surveys may miss a fraction of typical star-forming main-sequence galaxies due to their edge-on orientation.}, archive = {J_ApJ}, author = {Akiyoshi Tsujita and Kotaro Kohno and Shuo Huang and Masamune Oguri and Ken-ichi Tadaki and Ian Smail and Hideki Umehata and Zhen-Kai Gao and Wei-Hao Wang and Fengwu Sun and Seiji Fujimoto and Tao Wang and Ryosuke Uematsu and Daniel Espada and Francesco Valentino and Yiping Ao and Franz E. Bauer and Bunyo Hatsukade and Fumi Egusa and Yuri Nishimura and Anton M. Koekemoer and Daniel Schaerer and Claudia Lagos and Miroslava Dessauges-Zavadsky and Gabriel Brammer and Karina Caputi and Eiichi Egami and Jorge González-López and Jean-Baptiste Jolly and Kirsten K. Knudsen and Vasily Kokorev and Georgios E. Magdis and Masami Ouchi and Sune Toft and John F. Wu and Adi Zitrin}, doi = {10.3847/1538-4357/adb41d}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {115}, shortjournal = {The Astrophys. J.}, title = {ALMA lensing cluster survey: Physical characterization of near-infrared-dark intrinsically faint ALMA sources at z = 2–4}, volume = {989}, year = {2025}, }
• (2025). CLUES. III. do user choices impact the results of SED fitting? tests of “Off-the-shelf” stellar population and dust extinction models in the CLUES sample. ApJ, 989(1), 114. (www)

  @article{ , abstract = {The simple stellar population models produced by stellar population and spectral synthesis (SPS) codes are used as spectral templates in a variety of astrophysical contexts. In this paper, we test the predictions of four commonly used stellar population synthesis codes (YGGDRASIL, BPASS, FSPS, and a modified form of GALAXEV, which we call GALAXEVneb) by using them as spectral templates for photometric spectral energy distribution (SED) fitting with a sample of 18 young stellar clusters. All clusters have existing Hubble Space Telescope (HST) Cosmic Origins Spectrograph far-UV spectroscopy that provides constraints on their ages as well as broadband photometry from HST Advanced Camera for Surveys and Wide Field Camera 3. We use model spectra that account for both nebular and stellar emission, and additionally test four extinction curves at different values of R V . We find that for individual clusters, choice of extinction curve and SPS model can introduce significant scatter into the results of SED fitting. Model choice can introduce scatter of 34.8 Myr in age, a factor of 9.5 in mass, and 0.40 mag in extinction. Extinction curve choice can introduce scatter of up to a factor of 32.3 Myr in age, a factor of 10.4 in mass, and 0.41 mag in extinction. We caution that because of this scatter, one-to-one comparisons between the properties of individual objects derived using different SED fitting setups may not be meaningful. However, our results also suggest that SPS model and extinction curve choice do not introduce major systematic differences into SED fitting results when the entire cluster population is considered. The distribution of cluster properties for a large enough sample is relatively robust to user choice of SPS code and extinction curve.}, archive = {J_ApJ}, author = {Andrew Mizener and Daniela Calzetti and Angela Adamo and Aida Wofford and Matthew J. Hayes and John Chisholm and Michele Fumagalli and Svea Hernandez and Matteo Maria Messa and Linda J. Smith and Arjan Bik and Kathryn Grasha and Mattia Sirressi}, doi = {10.3847/1538-4357/ade391}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {114}, shortjournal = {The Astrophys. J.}, title = {CLUES. III. do user choices impact the results of SED fitting? tests of “Off-the-shelf” stellar population and dust extinction models in the CLUES sample}, volume = {989}, year = {2025}, }
• (2025). Comparative statistical analysis of prompt and afterglow X-ray flares in gamma-ray bursts: Insights into extended central engine activity. ApJ, 989(1), 113. (www)

  @article{ , abstract = {Gamma-ray bursts (GRBs) are the most energetic phenomena in the Universe, characterized by prompt gamma-ray emission followed by multiwavelength afterglows. X-ray flares, observed during the afterglow phase, are generally believed to originate from the prolonged activity of the central engine, though direct evidence has been scarce. In this study, we present a comprehensive statistical analysis of X-ray flares from 315 GRBs observed by the Swift/X-ray Telescope over nearly two decades. We categorize flares into prompt flares (occurring during the prompt emission phase) and afterglow flares and compare their temporal and luminosity properties. Our analysis reveals that both types of flares exhibit similar morphological characteristics, with prompt flares being brighter and occurring earlier than afterglow flares. We find strong correlations between flare parameters, such as peak time, duration, and luminosity, which follow consistent patterns across both flare types. These findings suggest that X-ray flares, regardless of their timing, share a common origin in the central engine’s activity. Our results imply that the central engine’s activity duration extends beyond the prompt gamma-ray emission phase, highlighting the importance of considering X-ray flares when studying GRB progenitors and central engine properties. This work provides robust statistical evidence supporting the central engine origin of X-ray flares and underscores the need for future observations with missions like the Space-based multi-band astronomical Variable Objects Monitor and Einstein Probe to further elucidate the nature of GRB central engines.}, archive = {J_ApJ}, author = {Yinuo Ma and He Gao}, doi = {10.3847/1538-4357/ade4cb}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {113}, shortjournal = {The Astrophys. J.}, title = {Comparative statistical analysis of prompt and afterglow X-ray flares in gamma-ray bursts: Insights into extended central engine activity}, volume = {989}, year = {2025}, }
• (2025). Varstrometry for off-nucleus and dual sub-kpc AGN (VODKA): A mix of singles, lenses, and true duals at cosmic noon. ApJ, 989(1), 112. (www)

  @article{ , abstract = {Dual active galactic nuclei (AGNs), a phase in some galaxy mergers during which both central supermassive black holes (SMBHs) are active, are expected to be a key observable stage leading up to SMBH mergers. Constraining the population of dual AGNs in both the nearby and high- z Universe has proven to be elusive until very recently. We present a multiwavelength follow-up campaign to confirm the nature of a sample of 20 candidate dual AGNs at cosmic noon ( z ∼ 2) from the VODKA sample. Through a combination of Hubble Space Telescope and Very Large Array imaging, we refute the possibility of gravitational lensing in all but one target. We find evidence of dual AGNs in three systems, while seven exhibit a single AGN in galaxy pairs, through either strong radio emission or ancillary emission-line data. The remaining systems are confirmed as either quasar−star superpositions (seven) or nonlensed pairs (two) that require further investigations to establish AGN activity. Among the systems with radio detections, we find a variety of radio spectral slopes and UV/optical colors suggesting that our sample contains a range of AGN properties, from obscured radio-quiet objects to those with powerful synchrotron-emitting jets. This study presents one of the largest dedicated multiwavelength follow-up campaigns to date searching for dual AGNs at high redshift. We confirm several of the highest- z systems at small physical separations, thus representing some of the most evolved dual-AGN systems at the epoch of peak quasar activity known to date.}, archive = {J_ApJ}, author = {Arran C. Gross and Yu-Ching Chen and Masamune Oguri and Liam Nolan and Xin Liu and Yue Shen and Ming-Yang Zhuang and Junyao Li and Nadia L. Zakamska and Hsiang-Chih Hwang and Yuzo Ishikawa}, doi = {10.3847/1538-4357/ade671}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {112}, shortjournal = {The Astrophys. J.}, title = {Varstrometry for off-nucleus and dual sub-kpc AGN (VODKA): A mix of singles, lenses, and true duals at cosmic noon}, volume = {989}, year = {2025}, }
• (2025). Planetary obliquity excitation through pre-main-sequence stellar evolution. ApJ, 989(1), 111. (www)

  @article{ , abstract = {A planet’s axial tilt (“obliquity”) substantially affects its atmosphere and habitability. It is thus essential to comprehend the various mechanisms that can excite planetary obliquities, particularly at the primordial stage. Here, we explore planetary obliquity excitation induced by the early evolution of the host star. A young, distended star spins rapidly, resulting in a large gravitational quadrupole moment that induces nodal recession of the planet’s orbit. As the star contracts and spins down, the nodal recession frequency decreases and can cross the planet’s spin axis precession frequency. An adiabatic encounter results in the planet’s capture into a secular spin–orbit resonance and excites the obliquity to large values. We find that planets within a ≲ 1 au are most affected, but adiabatic capture depends on the initial stellar radius and spin rate. The overall picture is complicated by other sources of perturbation, including the disk, multiple planets, and tidal dissipation. Tides make it such that stellar oblateness-induced obliquity excitation is transient since tidal perturbations cause the resonance to break once high obliquities are reached. However, this early transient excitation is important because it can prime planets for long-term capture in a secular spin–orbit resonance induced by planet–planet interactions. Thus, although stellar oblateness-induced resonances are short-lived, they facilitate the prevalence of long-lived nonzero obliquities in exoplanets.}, archive = {J_ApJ}, author = {Sidhant Kumar Suar and Sarah C. Millholland}, doi = {10.3847/1538-4357/ade686}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {111}, shortjournal = {The Astrophys. J.}, title = {Planetary obliquity excitation through pre-main-sequence stellar evolution}, volume = {989}, year = {2025}, }
• (2025). A systematic search for MeV–GeV pulsar wind nebulae without gamma-ray detected pulsars. ApJ, 989(1), 110. (www)

  @article{ , abstract = {An increasing number of pulsar wind nebulae (PWNe) are being identified in the TeV band by ground-based Imaging Air Cherenkov Telescopes such that they constitute the dominant source class of Galactic TeV emitters. However, MeV–GeV PWN counterparts are still largely lacking. To date, only a dozen PWNe are identified by the Fermi–Large Area Telescope (LAT) in the MeV–GeV band. Most PWNe are located along the Galactic plane embedded within the prominent, diffuse Galactic γ -ray emission, which makes these sources difficult to disentangle from the bright diffuse background. We present a systematic search for γ -ray counterparts to known PWNe in the 300 MeV–2 TeV energy band using the Fermi–LAT. We target the locations of previously identified PWNe that lack detected Fermi–LAT pulsars to minimize associated pulsar contamination. The sample includes six previously identified Fermi PWNe and eight Fermi–LAT sources associated with PWNe. We report the analysis of 58 regions of interest and classify Fermi–LAT detected sources as either a likely PWN or a candidate PWN counterpart based on their morphological and spectral characteristics across the broadband spectrum. There are nine unidentified Fermi–LAT sources that we consider as likely PWN counterparts, which, if confirmed to be PWNe, would greatly increase the PWN population detected by the Fermi–LAT from 12 to 21. The remaining Fermi–LAT detected sources are considered weaker PWN candidates. A second approach in the systematic search for γ -ray emitting PWNe will involve studying the off-pulse phases of Fermi–LAT detected pulsars for the presence of an obscured PWN and will be reported in a subsequent paper.}, archive = {J_ApJ}, author = {The Fermi-LAT Collaboration and A. Acharyya and A. Adelfio and M. Ajello and L. Baldini and J. Ballet and C. Bartolini and J. Becerra Gonzalez and R. Bellazzini and E. Bissaldi and R. Bonino and P. Bruel and R. A. Cameron and P. A. Caraveo and F. Casaburo and F. Casini and D. Castro and E. Cavazzuti and S. Ciprini and G. Cozzolongo and P. Cristarella Orestano and F. Cuna and S. Cutini and F. D’Ammando and D. Depalo and N. Di Lalla and A. Dinesh and L. Di Venere and A. Domínguez and J. Eagle and A. Fiori and Y. Fukazawa and S. Funk and P. Fusco and F. Gargano and C. Gasbarra and D. Gasparrini and S. Germani and F. Giacchino and N. Giglietto and M. Giliberti and F. Giordano and M. Giroletti and D. Green and I. A. Grenier and M.-H. Grondin and S. Guiriec and R. Gupta and A. K. Harding and M. Hashizume and E. Hays and J. W. Hewitt and D. Horan and X. Hou and T. Kayanoki and M. Kuss and A. Laviron and M. Lemoine-Goumard and A. Liguori and J. Li and I. Liodakis and P. Loizzo and F. Longo and F. Loparco and L. Lorusso and M. N. Lovellette and P. Lubrano and S. Maldera and D. Malyshev and G. Martí-Devesa and M. N. Mazziotta and I. Mereu and P. F. Michelson and N. Mirabal and T. Mizuno and P. Monti-Guarnieri and M. E. Monzani and A. Morselli and I. V. Moskalenko and N. Omodei and E. Orlando and D. Paneque and G. Panzarini and M. Persic and M. Pesce-Rollins and R. Pillera and T. A. Porter and G. Principe and S. Rainò and R. Rando and M. Razzano and A. Reimer and O. Reimer and M. Sánchez-Conde and P. M. Saz Parkinson and D. Serini and C. Sgrò and E. J. Siskind and G. Spandre and P. Spinelli and A. W. Strong and H. Tajima and J. B. Thayer and L. Tibaldo and D. F. Torres and J. Valverde and K. Wood and G. Zaharijas and W. Zhang}, doi = {10.3847/1538-4357/ade8f0}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {110}, shortjournal = {The Astrophys. J.}, title = {A systematic search for MeV–GeV pulsar wind nebulae without gamma-ray detected pulsars}, volume = {989}, year = {2025}, }
• (2025). Semi-analytical model for the dynamical evolution of planetary systems via giant impacts. ApJ, 989(1), 109. (www)

  @article{ , abstract = {In the standard model of terrestrial planet formation, planets are formed through giant impacts of planetary embryos after the dispersal of the protoplanetary gas disk. Traditionally, N -body simulations have been used to investigate this process. However, they are computationally too expensive to generate sufficient planetary populations for statistical comparisons with observational data. A previous study introduced a semi-analytical model that incorporates the orbital and accretionary evolution of planets due to giant impacts and gravitational scattering. This model succeeded in reproducing the statistical features of planets in N -body simulations near 1 au around solar-mass stars. However, this model is not applicable to close-in regions (around 0.1 au) or low-mass stars because the dynamical evolution of planetary systems depends on the orbital radius and stellar mass. This study presents a new semi-analytical model applicable to close-in orbits around stars of various masses, validated through comparison with N -body simulations. The model accurately predicts the final distributions of planetary mass, semimajor axis, and eccentricity for wide ranges of orbital radius, initial planetary mass, and stellar mass, with significantly reduced computation time compared to N -body simulations. By integrating this model with other planet-forming processes, a computationally low-cost planetary population synthesis model can be developed.}, archive = {J_ApJ}, author = {Tadahiro Kimura and Haruka Hoshino and Eiichiro Kokubo and Yuji Matsumoto and Masahiro Ikoma}, doi = {10.3847/1538-4357/ade992}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {109}, shortjournal = {The Astrophys. J.}, title = {Semi-analytical model for the dynamical evolution of planetary systems via giant impacts}, volume = {989}, year = {2025}, }
• (2025). The impact of wind accretion in evolving symbiotic systems. ApJ, 989(1), 108. (www)

  @article{ , abstract = {We investigate the impact of geometric corrections to the Bondi–Hoyle–Lyttleton (BHL) accretion scheme applied to evolving symbiotic systems. We model systems where 0.7 and 1 M ⊙ white dwarfs (WDs) accrete material from solar-like stars with initial masses of 1, 2, and 3 M ⊙ . The primary star is evolved using the MESA stellar evolution code, while the orbital dynamics of the system are calculated using REBOUND. The analysis focuses on systems evolving through the red giant branch and the thermally pulsating asymptotic giant branch phases that do not experience a wind Roche lobe overflow phase. We compare three scenarios: no accretion, standard BHL accretion, and the improved wind accretion. The choice of accretion prescription critically influences the evolution of symbiotic systems. Simulations using the modified model did not reach the Chandrasekhar limit, suggesting that Type Ia supernova progenitors require accretors originating from ultramassive WDs. In contrast, the standard BHL model predicts WD growth to this limit in compact systems. This discrepancy suggests that population synthesis studies adopting the traditional BHL approach may yield inaccurate results. The revised model successfully reproduces the accretion properties of observed symbiotic systems and predicts transitions between different accretion regimes driven by donor mass-loss variability. These results emphasize the need for updated wind accretion models to accurately describe the evolution of symbiotic binaries.}, archive = {J_ApJ}, author = {Raul F. Maldonado and Jesús A. Toalá and Janis B. Rodríguez-González and Emilio Tejeda}, doi = {10.3847/1538-4357/ade9a5}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {108}, shortjournal = {The Astrophys. J.}, title = {The impact of wind accretion in evolving symbiotic systems}, volume = {989}, year = {2025}, }
• (2025). The growth of galaxy stellar haloes over 0.2 ≤ z ≤ 1.1. ApJ, 989(1), 107. (www)

  @article{ , abstract = {Galaxies are predicted to assemble their stellar haloes through the accretion of stellar material from interactions with their cosmic environment. Observations that trace stellar halo buildup probe the processes that drive galaxy size and stellar mass growth. We investigate stellar halo assembly over 0.2 ≤ z ≤ 1.1 in a mass-complete ( M ⋆ ≥ 10 9.5 M ⊙ ) sample of 242,456 star-forming galaxies (SFGs) and 88,421 quiescent galaxies (QGs) from the CLAUDS and HSC-SSP surveys. We extract galaxy rest-frame g -band surface brightness ( μ g ) profiles to study faint, extended emission in galaxy outskirts. We examine trends in galaxy assembly by analyzing the median μ g profiles in different SFG and QG M ⋆ ranges with decreasing redshift and connecting evolution in galaxy μ g profiles with the underlying stellar mass growth in galaxies. Since z = 1.1, the majority of evolution in the median μ g profiles of galaxies (∼64% in SFGs and ∼71% in QGs) occurs throughout their stellar halo regions (2–10 R e ). More-massive galaxies assemble stellar halo material more rapidly at 0.2 ≤ z ≤ 1.1. Over this period, QGs grow a larger fraction of their stellar haloes than SFGs at fixed M ⋆ (factor of ∼1.2). Although star formation can account for the stellar halo growth observed in low-mass SFGs (10 9.5 M ⊙ ≤ M ⋆ < 10 10.5 M ⊙ ), high-mass SFGs ( M ⋆ ≥ 10 10.5 M ⊙ ), and both low- and high-mass QGs require an additional assembly mechanism. Our results suggest accretion via minor mergers drives additional stellar halo growth in these galaxies. The contribution from accretion is larger in more-massive galaxies (over M ⋆ ≥ 10 9.5 M ⊙ ), and QGs exhibit larger fractional increases to their ex situ fractions over 0.2 ≤ z ≤ 1.1 than SFGs at fixed M ⋆ .}, archive = {J_ApJ}, author = {Devin J. Williams and Ivana Damjanov and Marcin Sawicki and Harrison Souchereau and Lingjian Chen and Guillaume Desprez and Angelo George and Marianna Annunziatella and Stéphane Arnouts and Stephen Gwyn and Danilo Marchesini and Anna Sajina}, doi = {10.3847/1538-4357/ade9a8}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {107}, shortjournal = {The Astrophys. J.}, title = {The growth of galaxy stellar haloes over 0.2 ≤ z ≤ 1.1}, volume = {989}, year = {2025}, }
• (2025). Deterministic and stochastic study of the X-ray emission from the TeV blazar mrk 421. ApJ, 989(1), 106. (www)

  @article{ , abstract = {We present a comprehensive timing analysis of X-ray data from the XMM-Newton satellite, examining 50 light curves covering 17 yr of observations of the blazar Mrk 421. This work uses classical deterministic and stochastic methods in a novel way, enabling the distinction of temporal scales and offering essential insights through correlations among parameters. Deterministic behaviors are primarily explored through recurrence quantification analysis, used innovatively by varying the threshold input parameter to examine variability at multiple temporal scales. To investigate the behavior across various scales from a stochastic perspective, we apply both autoregressive moving average and autoregressive integrated moving average (ARIMA) models, with the results from ARIMA being more tightly related to short scales. Our findings reveal that Mrk 421’s X-ray emission is a multifaceted process, driven by both deterministic and stochastic patterns, indicating a complex interplay of physical phenomena. Our study demonstrates that deterministic patterns are more pronounced at small temporal scales, which are disconnected from large scales. On the other hand, stochastic processes with memory propagate from large to small timescales, while noise affects both scales, as indicated by the correlation analysis. These results underscore the importance of using advanced methodologies for interpreting astrophysical data, contributing to ongoing discussions in blazar physics by exploring connections between our calculated parameters and established models. The same approach can potentially be applied to other sources, enhancing our general understanding of the variability and emission mechanisms in blazars.}, archive = {J_ApJ}, author = {Radim Pánis and Gopal Bhatta and Tek P. Adhikari and Maksym Mohorian and Suvas Chandra Chaudhary and Adithiya Dinesh and Rajesh K. Bachchan and Niraj Dhital and Zdeněk Stuchlík}, doi = {10.3847/1538-4357/ade9b1}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {106}, shortjournal = {The Astrophys. J.}, title = {Deterministic and stochastic study of the X-ray emission from the TeV blazar mrk 421}, volume = {989}, year = {2025}, }
• (2025). Double compact binary merger rate density in open star clusters: Black holes, neutron stars, and white dwarfs. ApJ, 989(1), 105. (www)

  @article{ , abstract = {Studying compact object binary mergers in star clusters is crucial for understanding stellar evolution and dynamical interactions in galaxies. Open clusters in particular are more abundant over cosmic time than globular clusters. However, previous research on low-mass clusters with ≲10 3 M ⊙ has focused on binary black holes (BBHs) or black hole–neutron star (BH–NS) binaries. Binary mergers of other compact objects, such as white dwarfs (WDs), are also crucial as progenitors of transient phenomena such as Type Ia supernovae and fast radio bursts (FRBs). We present simulations of three types of open clusters with masses of 10 2 , 10 3 , and 10 4 M ⊙ . In massive clusters with ≳10 4 M ⊙ , BBHs are dynamically formed; however, less massive compact binaries such as WD–WDs and WD–NSs are perturbed inside the star clusters, causing them to evolve into other objects. We further find BH–NS mergers only in 10 3 M ⊙ clusters. Considering star clusters with a typical open cluster mass, we observe that WD–WD merger rates slightly increase for 10 3 M ⊙ clusters but decrease for 10 2 M ⊙ clusters. Since the host clusters are tidally disrupted, most of them merge outside of the clusters. Our WD–WD merger results have further implications for two classes of transients. Super-Chandrasekhar WD–WD mergers are present in our simulations, demonstrating potential sources of FRBs at a rate of 70–780 Gpc −3 yr −1 , higher than the rate estimated for globular clusters. Additionally, we find that carbon–oxygen WD–WD mergers in our open clusters (34–640 Gpc −3 yr −1 ) only account for 0.14%–2.6% of the observed Type Ia supernova rate in our local Universe.}, archive = {J_ApJ}, author = {Savannah Cary and Michiko Fujii and Long Wang and Ataru Tanikawa}, doi = {10.3847/1538-4357/ade9b6}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {105}, shortjournal = {The Astrophys. J.}, title = {Double compact binary merger rate density in open star clusters: Black holes, neutron stars, and white dwarfs}, volume = {989}, year = {2025}, }
• (2025). Stellar dynamics in open clusters increases the binary fraction and mass ratios: Evidence from photometric binaries in 35 open clusters. ApJ, 989(1), 104. (www)

  @article{ , abstract = {Using the Bayesian Analysis of Stellar Evolution-9 code and Gaia DR3, Pan-STARRS, and 2MASS data, we identify photometric binaries in 35 open clusters (OCs) and constrain their masses. We find a strong correlation between the binary fraction and cluster dynamical age and an even stronger correlation between core binary fraction and cluster dynamical age. We find that the binary mass-ratio ( q ) distribution of dynamically young OCs is statistically distinct from that of the old OCs. On average, dynamically young OCs display multimodal q distributions rising toward unity and toward our detection limit of q = 0.5 while more dynamically evolved clusters display more uniform q distributions, often with a peak near q = 1. Interestingly, the uniform q distribution with a peak near q = 1 is consistent with binaries in the field. We also observe a similar transition from multimodal to unimodal q distributions when comparing low-mass to high-mass OCs in our sample. Finally, we find a correlation between the median q of the binary population in a cluster and the cluster dynamical age. We interpret these results as an indication that dynamical encounters tend to increase the fraction of high-mass-ratio binaries within a given cluster—in particular within the cluster’s core, where stellar dynamics are likely more important. This may be the result of stellar exchanges that tend to produce binaries with larger q and/or the preferential disruption or evaporation of lower- q binaries.}, archive = {J_ApJ}, author = {Anna C. Childs and Aaron M. Geller}, doi = {10.3847/1538-4357/ade9bc}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {104}, shortjournal = {The Astrophys. J.}, title = {Stellar dynamics in open clusters increases the binary fraction and mass ratios: Evidence from photometric binaries in 35 open clusters}, volume = {989}, year = {2025}, }
• (2025). The type ia supernova and asymptotic giant branch stellar ejecta-regulated interstellar medium of massive galaxies. ApJ, 989(1), 103. (www)

  @article{ , abstract = {Observations and theory suggest that Type Ia supernovae (SNIa) heating and mass loss from asymptotic giant branch (AGB) stars play a crucial role in the interstellar medium (ISM) of massive galaxies. We perform 3D hydrodynamic simulations of the central few kiloparsecs of massive galaxies, including radiative cooling and mass and energy injection from AGB winds and SNIa (resolving each SNIa remnant, a few ×10 pc in size), excluding black hole feedback. We study systems with different initial core thermodynamic profiles, focusing on NGC 1399. Our fiducial simulation reproduces its observed density and entropy profiles well. Over 100 Myr, two steady-state profiles emerge, depending on the inner circumgalactic medium (CGM) pressure and the ratio of Ia heating to cooling: (i) if SNIa heating is less than cooling, a cooling flow develops; (ii) if SNIa heating is comparable to or exceeds cooling, SNIa heating drives a slow subsonic outflow of AGB ejecta, with black hole accretion at small radii. This outflow, pressure-confined by the CGM, adapts the ISM to the CGM properties: a low-entropy CGM results in a dense, low-entropy ISM with higher black hole accretion, while a high-entropy CGM leads to a less dense, high-entropy ISM with lower accretion. This suggests that the AGB-SNIa-regulated ISM connects CGM and galaxy scales, potentially influencing black hole feedback in massive halos. Approximate methods of modeling Ia heating, such as clustered SNIa and smoothly distributed heating, produce unrealistic ISM profiles over 100 Myr, highlighting the importance of resolving SNIa in simulations.}, archive = {J_ApJ}, author = {Rajsekhar Mohapatra and Eliot Quataert and Drummond Fielding and Minghao Guo}, doi = {10.3847/1538-4357/adea6c}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {103}, shortjournal = {The Astrophys. J.}, title = {The type ia supernova and asymptotic giant branch stellar ejecta-regulated interstellar medium of massive galaxies}, volume = {989}, year = {2025}, }
• (2025). Sleeping giants arise: Monitoring the return of three changing-look quasars to their high states*. ApJ, 989(1), 102. (www)

  @article{ , abstract = {Changing-look quasars (CLQs) challenge many models of the quasar central engine. Their extreme variability in both the continuum and broad emission-line fluxes on timescales on the order of years is difficult to explain. To investigate the cause of the observed transitions, we present new contemporaneous optical and X-ray observations of three faded CLQs as they return to a state of high optical luminosity. Two of these three remained in a quiescent state for more than 10 yr before returning to a new high state. We find that before, during, and after transition, the spectral energy distributions of all three follow predictions for quasars based on X-ray binary outbursts, suggesting that the underlying mechanism is likely a changing accretion rate causing changes in the accretion flow structure. In two of the three cases, the transition between the initial high and low state and the transition between the low and new high state took nearly identical amounts of time, on the order of hundreds of days. This transition timescale is a useful constraint on models of the accretion state changes. The behavior of the broad emission-line profiles suggests that the broad-line region structure is changing during the transition.}, archive = {J_ApJ}, author = {Laura Duffy and Michael Eracleous and John J. Ruan and Qian Yang and Jessie C. Runnoe}, doi = {10.3847/1538-4357/adeb73}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {102}, shortjournal = {The Astrophys. J.}, title = {Sleeping giants arise: Monitoring the return of three changing-look quasars to their high states*}, volume = {989}, year = {2025}, }
• (2025). Modeling star formation histories of changing-look AGN host galaxies with prospector. ApJ, 989(1), 101. (www)

  @article{ , abstract = {Changing-look active galactic nuclei (CL-AGNs), are AGNs that appear to transition between Seyfert Type 1 and 2 over periods of months to years. Several mechanisms to trigger these transitions have been proposed, but we have yet to conclusively determine their cause. Recent studies suggest CL-AGNs are hosted primarily in galaxies that are shutting down star formation (S. A. Dodd et al. 2021 ; W.-J. Liu et al. 2021 ; J. Wang et al. 2023 ), which may indicate a link between galaxy quenching and changing-look events. We use Prospector stellar population synthesis software (B. Johnson & J. Leja 2017 ; J. Leja et al. 2017 ; B. D. Johnson et al. 2021 ) to model nonparametric star formation histories for 39 CL-AGN host galaxies. We find that 4{3}_{-12}^{+13} \% of our gold sample CL-AGNs at z < 0.15 are star-forming, while 2{9}_{-10}^{+13} \% fall in the Green Valley of the stellar mass–specific star formation rate diagram. At z > 0.15, 5{7}_{-18}^{+13} \% of CL-AGNs in the gold sample are star-forming and 2{9}_{-14}^{+19} \% are in the Green Valley. CL-AGN hosts have similar star formation properties to the host galaxies of Seyfert 1 and 2 AGNs at z < 0.15 and to Seyfert 2 AGNs at z > 0.15. We find no statistically significant differences in the star formation properties of turn-on and turn-off CL-AGNs. We also find no evidence for rapid quenching in the Green Valley CL-AGNs. We conclude that CL-AGN state transitions are not associated with the formation history of CL-AGN host galaxies on large spatial scales, implying CL-AGN state transitions may instead result from nuclear-scale or accretion disk effects.}, archive = {J_ApJ}, author = {Margaret E. Verrico and K. Decker French and Katherine A. Suess and Tanay Agrawal and Lauranne Lanz and Yuanze Luo and Pallavi Patil and Kate Rowlands and Margaret Shepherd and Maya Skarbinski}, doi = {10.3847/1538-4357/adeb88}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {101}, shortjournal = {The Astrophys. J.}, title = {Modeling star formation histories of changing-look AGN host galaxies with prospector}, volume = {989}, year = {2025}, }
• (2025). Observational constraints on cool gas clouds in m82’s starburst-driven outflow. ApJ, 989(1), 100. (www)

  @article{ , abstract = {Star formation feedback can drive large-scale, multiphase galactic outflows. The dynamical and thermodynamical interaction between the hot and cooler phases is a prime focus of both observational and theoretical work. Here, we analyze H α -emitting structures in the extraplanar wind of the nearby starburst M82. We use high-resolution, narrowband, observations from the Hubble Legacy Archive. Our analysis constrains the morphology, number density, and column density of the structures. We highlight conspicuous arc-like structures that differ significantly from the linear cometary clouds that emerge from galactic wind simulations and discuss their possible origins, such as bow shocks or instabilities driven by cosmic rays. The most prominent structures range in size from ∼24 to 110 pc. Using the H α brightness and assumptions about the depth of the emitting structures, we estimate number densities of ∼1–23 cm −3 assuming a unity volume filling factor, which are lower than previous constraints from spectroscopic nebular line studies. The derived column densities, ∼10 20 –10 21 cm −2 , along the path of the outflow are above theoretical thresholds for cool cloud survival in a hot supersonic background, but small enough that the structures could be accelerated by the hot wind momentum. Using diffuse X-ray emission maps from Chandra, we also find that even on small (∼100 pc) scales, the H α “leads” the X-rays, a behavior long noted in the literature on kiloparsec scales. This behavior, along with previous observational studies of ionization in the wind, may signal that shock ionization is responsible for the H α emission we observe.}, archive = {J_ApJ}, author = {Sebastian Lopez and Laura A. Lopez and Todd A. Thompson and Adam K. Leroy and Alberto D. Bolatto}, doi = {10.3847/1538-4357/adec75}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {100}, shortjournal = {The Astrophys. J.}, title = {Observational constraints on cool gas clouds in m82’s starburst-driven outflow}, volume = {989}, year = {2025}, }
• (2025). Interpreting the multi-TeV emission from GRB 221009A with a second electron component accelerated by turbulence in the jet. ApJ, 989(1), 99. (www)

  @article{ , abstract = {The detection of very high-energy afterglow emission of the gamma-ray burst (GRB) 221009A by the Large High Altitude Air Shower Observatory (LHAASO) provides a unique opportunity to probe particle acceleration in relativistic outflows. The hard spectrum at the multi-TeV band cannot be fully explained by synchrotron-self-Compton radiation of the conventional one-zone afterglow model. In this work, we introduce a second component of relativistic electrons from stochastic acceleration via downstream turbulence of the external shock. Using a Fokker–Planck approach to model the evolution of protons and electrons, and the nonlinear feedback of turbulence damping, we show that the inverse Compton radiation of the second electron component may harden the observed spectrum above multi-TeV energy, and significantly ameliorate the fitting to the spectral evolution measured by LHAASO without violating lower-energy observations. We also discuss the potential presence of the second electron component in other GRB afterglows, which may provide a possible observational signature for future studies.}, archive = {J_ApJ}, author = {Xing-Wei Gong and Ruo-Yu Liu and Ze-Lin Zhang and Katsuaki Asano and Martin Lemoine}, doi = {10.3847/1538-4357/aded8d}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {99}, shortjournal = {The Astrophys. J.}, title = {Interpreting the multi-TeV emission from GRB 221009A with a second electron component accelerated by turbulence in the jet}, volume = {989}, year = {2025}, }
• (2025). The MASSIVE survey. XX. a triaxial stellar dynamical measurement of the supermassive black hole mass and intrinsic galaxy shape of giant radio galaxy NGC 315. ApJ, 989(1), 98. (www)

  @article{ , abstract = {We present a new dynamical measurement of the supermassive black hole mass and intrinsic shape of the stellar halo of the massive radio galaxy NGC 315 as part of the MASSIVE survey. High signal-to-noise ratio spectra from integral-field spectrographs at the Gemini and McDonald Observatories provide stellar kinematic measurements in 304 spatial bins from the central \sim 0\mathop{.}\limits^{^{\prime\prime} }3 out to 30 ″ . Using ∼2300 kinematic constraints, we perform triaxial stellar orbit modeling with the TriOS code and search over ∼15,000 galaxy models with a Bayesian scheme to simultaneously measure six mass and intrinsic shape parameters. NGC 315 is triaxial and highly prolate, with middle-to-long and short-to-long axis ratios of p = 0.854 and q = 0.833, and a triaxiality parameter of T = 0.89. The black hole mass inferred from our stellar kinematics is {M}_{{\rm{BH}}}=\left(3.0\pm 0.3\right)\times 1{0}^{9}\,{M}_{\odot } , which is higher than {M}_{{\rm{BH}}}=(1.9{6}_{-0.13}^{+0.30})\times 1{0}^{9}{M}_{\odot } inferred from CO kinematics (scaled to our distance). When the seven galaxies with M BH measurements from both stellar and CO kinematics are compared, we find an intrinsic scatter of 0.28 dex in M BH from the two tracers and do not detect statistically significant biases between the two methods in the current data. The implied black hole shadow size (≈4.7 μ as) and the relatively high millimeter flux of NGC 315 makes this galaxy a prime candidate for future horizon-size imaging studies.}, archive = {J_ApJ}, author = {Jacob Pilawa and Emily R. Liepold and Chung-Pei Ma and Jonelle L. Walsh and Jenny E. Greene}, doi = {10.3847/1538-4357/adee1e}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {98}, shortjournal = {The Astrophys. J.}, title = {The MASSIVE survey. XX. a triaxial stellar dynamical measurement of the supermassive black hole mass and intrinsic galaxy shape of giant radio galaxy NGC 315}, volume = {989}, year = {2025}, }
• (2025). Propagating and stationary bright knots in the quiet solar corona. ApJ, 989(1), 97. (www)

  @article{ , abstract = {Small-sized localized brightenings are an important candidate for resolving the problem of the solar atmospheric heating. They are spread over the whole solar disk and are suggested to be caused by magnetic reconnection or wave dissipation. In the chromosphere, two kinds of bright knots (propagating bright knots and stationary ones) have been reported. In this paper, we employ the data from the Solar Dynamics Observatory to study the distribution of two kinds of the bright knots in the quiet corona. To avoid the influence of active regions, we choose the data from 2020 July 20, on which no sunspot was detected in the solar disk. Based on the observations of 3 hr duration (from 00:00 UT to 03:00 UT), 815 propagating bright knots and 19,043 stationary ones are detected. The propagating bright knots have an average area of 1.5 Mm 2 , lifetime of 51 s, and velocity of 33 km s −1 . For the stationary ones, the average area and lifetime are 2.0 Mm 2 and 367 s, respectively. The propagating knots are located in weak magnetic field regions with an average flux density of 9.0 Gauss, which is comparable with the noise level, and their number is affected by the background radiation, e.g., the stronger the radiation, the less the propagating knots. The stationary knots are located at the locations of network fields with an average flux density of 14.4 Gauss. We suggest that the propagating bright knots are excited by wave dissipation, while the stationary knots result from magnetic reconnection.}, archive = {J_ApJ}, author = {Shaoxuan Tong and Jun Zhang}, doi = {10.3847/1538-4357/adef44}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {97}, shortjournal = {The Astrophys. J.}, title = {Propagating and stationary bright knots in the quiet solar corona}, volume = {989}, year = {2025}, }
• (2025). Monogem’s contribution to the galactic cosmic-ray spectrum. ApJ, 989(1), 96. (www)

  @article{ , abstract = {The study of local cosmic-ray (CR) sources is crucial for understanding the anomalous features observed in the energy spectra of CR nuclei, as well as the reversal of both the amplitude and phase of CR anisotropy around 100 TeV. Among the candidate sources, Geminga and Monogem are frequently considered primary contributors to the observed CR spectrum. However, the precise role of Monogem remains an open question. In this work, we conduct a detailed reanalysis of the contributions from these two local sources using a three-dimensional, spatially dependent propagation model that explicitly accounts for the halo structure of CR sources. Our findings indicate that within this framework, CRs originating from Monogem are largely prevented from reaching Earth due to obstruction by the Geminga pulsar halo. Consequently, Geminga emerges as the dominant contributor to the local CR spectrum.}, archive = {J_ApJ}, author = {Xiang-Li Qian and Hui-Ying Sun and Lin Nie and Yu-Hai Ge and Wei Liu and Yi-Qing Guo}, doi = {10.3847/1538-4357/adef51}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {96}, shortjournal = {The Astrophys. J.}, title = {Monogem’s contribution to the galactic cosmic-ray spectrum}, volume = {989}, year = {2025}, }
• (2025). A framework for modeling the evolution of young stellar objects. ApJ, 989(1), 95. (www)

  @article{ , abstract = {Measuring properties of young stellar objects (YSOs) is necessary for probing the pre-main-sequence evolution of stars. As YSOs exhibit complex geometry, measurement generally entails comparing observed radiation to template populations of radiative-transfer model YSO spectral energy distributions (SEDs). Due to uncertainty on the precise mechanics of star formation, the properties inferred for YSOs using these models often depend strongly on the assumed accretion history. We develop a framework for predicting observable properties of YSOs that is agnostic to the underlying accretion history, enabling comparison between theories. This framework links a set of radiative-transfer SEDs with protostellar evolutionary tracks to create models of evolving YSOs. Unlike previous works, we directly relate evolution models to observables through theoretical physical parameters rather than through intermediate, observationally derived analogs. We make flux predictions for YSOs corresponding to stars with birth masses from 0.2 to 50 M ⊙ during their accretion phase following isothermal-sphere, turbulent-core, and competitive accretion histories, showing that these histories may be observationally distinguished by examining the 100 μ m and 3 mm fluxes of a YSO. We discuss the impact of dust models and parameter ranges on the output of radiative-transfer simulations through a comparison to another SED model grid. We quantify the degree of confusion between YSO Stages and Classes across a wide range of physical scenarios; for each, we calculate confusion matrices that enable inference of the number of objects of a given Stage from an observed population. Finally, we critically examine the physical significance of various literature Stage and Class definitions.}, archive = {J_ApJ}, author = {Theo Richardson and Adam Ginsburg and Erik Rosolowsky and Joshua Peltonen and Rémy Indebetouw}, doi = {10.3847/1538-4357/ade99d}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {95}, shortjournal = {The Astrophys. J.}, title = {A framework for modeling the evolution of young stellar objects}, volume = {989}, year = {2025}, }
• (2025). Spherically symmetric accretion with self-gravity: Analytical formulae and numerical validation. ApJ, 989(1), 94. (www)

  @article{ , abstract = {Spherically symmetric accretion incorporating self-gravity constitutes a three-point boundary value problem (TPBVP) governed by constraints at the outer boundary, sonic point, and accretor surface. Previous studies have two limitations: either employing an incorrect formula for self-gravity potential in analytical treatments, or introducing additional input parameters in numerical implementations to circumvent solving the full TPBVP. To address these issues, we present a self-consistent TPBVP formulation, solved using the relaxation method. We also derive approximate analytical formulae that enable rapid estimates of self-gravity effects. Our analysis identifies a dimensionless parameter \beta \equiv 2G\bar{\rho }{r}_{{\rm{out}}}^{2}/{a}_{{\rm{out}}}^{2} that characterizes the strength of self-gravity, where \bar{\rho } and r out are the mean density and outer radius of the flow, respectively, and a out is the adiabatic sound speed of the external medium. For practical estimation, \bar{\rho } may be approximated by the external medium density ρ out . We identify an upper limit for β , beyond which steady accretion becomes unsustainable—a behavior consistent with classical gravitational instability that previous studies failed to capture. The accretion rate enhancement decreases monotonically as the adiabatic index γ increases. For γ = 5/3, self-gravity ceases to augment the accretion rate. These theoretical predictions are validated by our numerical solutions. We further apply our results to two astrophysical scenarios: hyper-Eddington accretion onto supermassive black hole seeds in the early Universe, where self-gravity is significant; and accretion onto stellar-mass objects embedded in active galactic nuclei disks, where self-gravity is non-negligible under certain conditions and should be evaluated using β .}, archive = {J_ApJ}, author = {Cheng-Liang Jiao and Er-gang Zhao and Liying Zhu and Xiang-dong Shi}, doi = {10.3847/1538-4357/adec71}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {94}, shortjournal = {The Astrophys. J.}, title = {Spherically symmetric accretion with self-gravity: Analytical formulae and numerical validation}, volume = {989}, year = {2025}, }
• (2025). Spectroscopy of ClS2 isomers: Implications for Sulfur–Chlorine chemistry. ApJ, 989(1), 93. (www)

  @article{ , abstract = {Chlorine–sulfur chemistry plays a significant role in the atmospheric processes of Venus, yet many aspects remain unclear, despite decades of study. This work presents a theoretical investigation into the photochemistry of ClSS and SClS isomers using high-level ab initio methods. ClSS is predicted to be the most stable isomer, exhibiting two significant absorption peaks at 384 and 243 nm. The 243 nm absorption may lead to photodissociation (yielding S, ClS, or S 2 ) or fluorescence back to the ground state, while absorption at 384 nm produces Cl and S 2 . In contrast, SClS is predicted to be photochemically unstable. A comprehensive set of spectroscopic constants for both isomers is provided, to support future experimental detections and astronomical observations. Although atmospheric models of Venus suggest ClS 2 abundances are likely too low, the calculated spectrum of ClSS shows significant overlap with the 320–400 nm range of Venus’ enigmatic near-UV absorber. This study establishes essential spectroscopic benchmarks for ClS 2 isomers, advancing our understanding of sulfur–chlorine photochemical networks in Venus and related environments.}, archive = {J_ApJ}, author = {Tarek Trabelsi and Joseph S. Francisco}, doi = {10.3847/1538-4357/aded85}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {93}, shortjournal = {The Astrophys. J.}, title = {Spectroscopy of ClS2 isomers: Implications for Sulfur–Chlorine chemistry}, volume = {989}, year = {2025}, }
• (2025). Data-driven radiative hydrodynamics simulations of the solar photosphere using physics-informed neural networks: Proof of concept. ApJ, 989(1), 92. (www)

  @article{ , abstract = {Current, realistic numerical simulations of the solar atmosphere reproduce observations in a statistical sense; they do not replicate observations such as a movie of solar granulation. Inversions on the other hand reproduce observations by design, but the resulting models are often not physically self-consistent. Physics-informed neural networks (PINNs) offer a new approach to solving the time-dependent radiative hydrodynamics equations and matching observations as boundary conditions. PINNs approximate the solution of the integro-differential equations with a deep neural network. The parameters of this network are determined by minimizing the residuals with respect to the physics equations and the observations. The resulting models are continuous in all dimensions, can zoom into local areas of interest in space and time, and provide information on physical parameters that are not necessarily directly observed such as horizontal velocities. Here, we present the first proof of concept of this novel approach, explain the underlying methodology in detail, and provide an outlook to the many applications that PINNs enable.}, archive = {J_ApJ}, author = {Christoph U. Keller}, doi = {10.3847/1538-4357/add6a9}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {92}, shortjournal = {The Astrophys. J.}, title = {Data-driven radiative hydrodynamics simulations of the solar photosphere using physics-informed neural networks: Proof of concept}, volume = {989}, year = {2025}, }
• (2025). Stellar mass calibrations for local low-mass galaxies. ApJ, 989(1), 91. (www)

  @article{ , abstract = {The stellar masses of galaxies are measured from integrated light via several methods—however, few of these methods were designed for low-mass ( M ⋆ ≲ 10 8 M ⊙ ) “dwarf” galaxies, whose properties (e.g., stochastic star formation, low metallicity) pose unique challenges for estimating stellar masses. In this work, we quantify the precision and accuracy at which stellar masses of low-mass galaxies can be recovered using UV/optical/IR photometry. We use mock observations of 469 low-mass galaxies from a variety of models, including both semi-empirical models (GRUMPY and UniverseMachine-SAGA) and cosmological baryonic zoom-in simulations (MARVELous Dwarfs and FIRE-2), to test literature color– M ⋆ / L relations and multiwavelength spectral energy distribution (SED) mass estimators. We identify a list of “best practices” for measuring stellar masses of low-mass galaxies from integrated photometry. We find that literature color– M ⋆ / L relations are often unable to capture the bursty star formation histories (SFHs) of low-mass galaxies, and we develop an updated prescription for stellar mass based on g − r color that is better able to recover stellar masses for the bursty low-mass galaxies in our sample (with ∼0.1 dex precision). SED fitting can also precisely recover stellar masses of low-mass galaxies, but this requires thoughtful choices about the form of the assumed SFH: Parametric SFHs can underestimate stellar mass by as much as ∼0.4 dex, while nonparametric SFHs recover true stellar masses with insignificant offset (−0.03 ± 0.11 dex). Finally, we also caution that noninformative (wide) dust attenuation priors may introduce M ⋆ uncertainties of up to ∼0.6 dex.}, archive = {J_ApJ}, author = {Mithi A. C. de los Reyes and Yasmeen Asali and Risa H. Wechsler and Marla Geha and Yao-Yuan Mao and Erin Kado-Fong and Ragadeepika Pucha and William Grant and Pratik J. Gandhi and Viraj Manwadkar and Anna Engelhardt and Ferah Munshi and Yunchong Wang}, doi = {10.3847/1538-4357/ade4c5}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {91}, shortjournal = {The Astrophys. J.}, title = {Stellar mass calibrations for local low-mass galaxies}, volume = {989}, year = {2025}, }
• (2025). Linear thermal instability of a condensing Gas–Particle mixture, with possible application to chondrites and planetesimals. ApJ, 989(1), 90. (www)

  @article{ , abstract = {We study the stability of a hot saturated gas coexisting with condensed particles in an optically thin medium. Such a situation may be obtained downstream of a shock, at condensation fronts, or in vaporizing impacts. We show that the gas–particle mixture is subject to a thermal instability whereby a region of lower temperature and higher condensate density cools faster to condense faster. If the region of runaway condensation has a sound-crossing time shorter than its cooling time, then it accretes more mass, in gas and particles, from its higher-pressure surroundings. Numerical integration of the linearized perturbation equations demonstrates that this radiation–condensation instability can create particle clumps and voids out of a secularly cooling gas. Provided radiation can escape to cool particle overdensities, thermal instability can help assemble chondrite parent bodies out of the vaporized debris of asteroid collisions and form planetesimals generally.}, archive = {J_ApJ}, author = {Kecheng Stephon Qian and Eugene Chiang}, doi = {10.3847/1538-4357/ade70d}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {90}, shortjournal = {The Astrophys. J.}, title = {Linear thermal instability of a condensing Gas–Particle mixture, with possible application to chondrites and planetesimals}, volume = {989}, year = {2025}, }
• (2025). Timing and spectral evolution of the magnetar 1E 1841-045 in outburst. ApJ, 989(1), 89. (www)

  @article{ , abstract = {We present timing and spectral analyses of Neutron star Interior Composition Explorer (NICER), Nuclear Spectroscopic Telescope Array (NuSTAR), and IXPE observations of the magnetar 1E 1841−045 covering 82 days following its 2024 August bursting activity as well as radio observations utilizing MeerKAT and Effelsberg. We supplement our study with a historical NuSTAR observation and all 2024 preoutburst NICER observations. The outburst is marked by an X-ray flux enhancement of a factor of 1.6 compared to the historical level, predominantly driven by a newly formed nonthermal emitting component with a photon index Γ = 1.5. This flux showed a 20% decay at the end of our monitoring campaign. The radio monitoring did not reveal any pulsed radio emission with an upper limit of 20 mJy and 50 mJy ms on the mean flux density and single pulse fluence, respectively. We detect a spin-up glitch at outburst onset with Δ ν = 6.1 × 10 −8 Hz and {\rm{\Delta }}\dot{\nu }=-1.4\times 1{0}^{-14} Hz s −1 , consistent with the near universality of this behavior among the continuously monitored magnetars. Most intriguingly, the 1E 1841−045 2–10 keV pulse profile is markedly different compared to preoutburst: it shows a new, narrow (0.1 cycle) peak that appears to shift toward merging with the main, persistently present, pulse. This is the second case of pulse-peak migration observed in magnetars after SGR 1830−0645, and the two sources exhibit a similar rate of phase shift. This implies that this phenomenon is not unique and might present itself in the broader population. The newly formed peak for 1E 1841−045 is nonthermal, with emission extending to ≳20 keV, in contrast to the case of SGR 1830−0645. Our results are consistent with an untwisting magnetic field bundle with migration toward the magnetic pole, perhaps accompanied by plastic motion of the crust.}, archive = {J_ApJ}, author = {George Younes and Samuel K. Lander and Matthew G. Baring and Marlon L. Bause and Rachael Stewart and Zaven Arzoumanian and Hoa Dinh Thi and Teruaki Enoto and Keith C. Gendreau and Tolga Güver and Alice K. Harding and Wynn C. G. Ho and Chin-Ping Hu and Alex Van Kooten and Chryssa Kouveliotou and Niccolò Di Lalla and Alexander McEwen and Michela Negro and Mason Ng and David M. Palmer and Laura G. Spitler and Zorawar Wadiasingh}, doi = {10.3847/1538-4357/ade716}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {89}, shortjournal = {The Astrophys. J.}, title = {Timing and spectral evolution of the magnetar 1E 1841-045 in outburst}, volume = {989}, year = {2025}, }
• (2025). BASS. XLVIII. [Ne v] λ3427 emission in powerful nearby active galactic nuclei. ApJ, 989(1), 88. (www)

  @article{ , abstract = {We investigate the high-ionization, narrow [Ne V ] λ 3427 line emission in a sample of over 340 ultrahard X-ray (14–195 keV) selected active galactic nuclei (AGN) drawn from the BAT AGN Spectroscopic Survey project. The analysis includes measurements in individual and stacked spectra and considers several key AGN properties such as X-ray luminosity, supermassive black hole (SMBH) mass, Eddington ratios, and line-of-sight column density. The [Ne V ] λ 3427 line is robustly detected in ≈43% (146/341) of the AGN in our sample, with no significant trends between the detection rate and key AGN/SMBH properties. In particular, the detection rate remains high even at the highest levels of obscuration (>70% for {\mathrm{log}}\,\left[{N}_{{\rm{H}}}/{\mathrm{cm}}^{-2}\right])\gtrsim 23 ). On the other hand, even some of our highest signal-to-noise spectra (S/N > 50) lack a robust [Ne v] detection. The typical (median) scaling ratios between [Ne v] line emission and (ultra)hard X-ray emission in our sample are {\mathrm{log}}\,{L}_{[{\rm{Ne}}\,{\rm\small{V}}]}/{L}_{14-150\,{\rm{keV}}}\simeq -3.75 and {\mathrm{log}}\,{L}_{[{\rm{Ne}}\,{\rm\small{V}}]}/{L}_{2-10\,{\rm{keV}}}\simeq -3.36 . The scatter on these scaling ratios, ≲0.5 dex, is comparable to, and indeed smaller than, what is found for other commonly used tracers of AGN radiative outputs (e.g., [O III ] λ 5007). Otherwise, we find no significant relations between the (relative) strength of [Ne v] and the basic AGN/SMBH properties under study, in contrast with simple expectations from models of SMBH accretion flows. Our results reaffirm the usability of [Ne v] as an AGN tracer even in highly obscured systems, including dual AGN and high-redshift sources.}, archive = {J_ApJ}, author = {Tomer Reiss and Benny Trakhtenbrot and Claudio Ricci and Franz E. Bauer and Michael J. Koss and Kohei Ichikawa and Darshan Kakkad and Richard Mushotzky and Kyuseok Oh and Alessandro Peca and Rudolf Bär and Yaherlyn Diaz and Fiona Harrison and Meredith C. Powell and Eleonora Sani and Daniel Stern and C. Megan Urry}, doi = {10.3847/1538-4357/ade879}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {88}, shortjournal = {The Astrophys. J.}, title = {BASS. XLVIII. [Ne v] λ3427 emission in powerful nearby active galactic nuclei}, volume = {989}, year = {2025}, }
• (2025). Comparing star formation histories and evolutionary pathways of post-starburst and E+A galaxies in TNG50 and SDSS-IV MaNGA. ApJ, 989(1), 87. (www)

  @article{ , abstract = {E+A galaxies represent a class of recently quenched objects, with spectra that show evidence of a previous substantial starburst and strong Balmer absorption lines indicative of A-type stellar populations. Using an SDSS-IV MaNGA–selected sample of E+A galaxies, we identify a matching sample in the TNG50 simulation to study their evolutionary histories. Additionally, we identify a sample of generic post-starburst (PSB) galaxies based on their star formation histories (SFHs) from the MaNGA Pipe3D value-added catalog. We find that PSB-like SFHs make up a similar fraction of galaxies in TNG50 (0.9% compared to MaNGA’s ∼1%). Matching galaxies based solely on their stellar masses and metallicities in TNG50 does not result in a sample with PSB-like histories. We analyzed the chemical enrichment histories of our selected simulated galaxy samples and found that both PSB and E+A galaxies exhibit a distinct episode of rapid enrichment when compared to galaxies in TNG50 with a similar stellar mass range. These galaxies are typically metal-poor before undergoing an extended ∼2 Gyr starburst, during which a phase of rapid chemical enrichment occurs over the first ∼300 Myr. The final systems are generally more metal-rich than the average galaxy in TNG50, while the MaNGA data do not show this trend. This suggests that PSB galaxies undergo unique evolutionary processes as they transition from starburst activity to quiescence. Further studies are needed to determine whether these galaxies originate from truly metal-poor progenitors and to better understand their subsequent evolution.}, archive = {J_ApJ}, author = {Eric Ludwig and Kartheik G. Iyer and Charles Liu and Eric Gawiser and Olivia A. Greene and Juan Pablo Alfonzo}, doi = {10.3847/1538-4357/ade882}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {87}, shortjournal = {The Astrophys. J.}, title = {Comparing star formation histories and evolutionary pathways of post-starburst and E+A galaxies in TNG50 and SDSS-IV MaNGA}, volume = {989}, year = {2025}, }
• (2025). Are gas-rich ultra-diffuse galaxies and field dwarfs distinct?. ApJ, 989(1), 86. (www)

  @article{ , abstract = {We explore the differences in gas-rich field ultra-diffuse galaxies (UDGs) and diffuse classical dwarf galaxies using an extensive atomic gas (H I ) follow-up survey of optically selected UDG candidates from the Systematically Measuring Ultra-diffuse Galaxies (SMUDGes) catalogue. We also compare the SMUDGes-H I observations with two state-of-the-art cosmological hydrodynamical simulations: Numerical Investigation of a Hundred Astrophysical Objects (NIHAO), where UDGs form through a series of bursty star formation episodes and R omulus 25, where UDGs form as a result of major mergers that temporarily increase their spin. Although the suggested formation scenarios for UDGs within these simulations are different, the present-day H I masses M H I , stellar masses M * , and star formation rates of simulated galaxies are qualitatively and quantitatively consistent with each other and with the observed SMUDGes-H I sample. We find that when controlling for M * , there is a positive correlation between the gas richness M H I / M * and the effective optical radius R eff , and that this trend is not different between the UDG and dwarf populations, within the measured scatter. Taken together, our results suggest that gas-rich, star-forming UDGs and dwarfs are not distinct galaxy populations, either observationally or in simulations.}, archive = {J_ApJ}, author = {Khadeejah Motiwala and Ananthan Karunakaran and Kristine Spekkens and Nikhil Arora and Arianna Di Cintio and Anna C. Wright and Dennis Zaritsky and Andrea V. Macciò}, doi = {10.3847/1538-4357/ade9a0}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {86}, shortjournal = {The Astrophys. J.}, title = {Are gas-rich ultra-diffuse galaxies and field dwarfs distinct?}, volume = {989}, year = {2025}, }
• (2025). Origin of radio emission in three nearby ultraluminous infrared galaxies with signatures of luminous buried active galactic nuclei. ApJ, 989(1), 85. (www)

  @article{ , abstract = {We report multifrequency Very Long Baseline Array (VLBA) observations at 2.3 and 8.4 GHz of three nearby ultraluminous infrared galaxies, identified via mid-infrared spectroscopic analyses as hosting deeply embedded active galactic nuclei (AGNs). Milliarcsecond-scale observations at both frequencies reveal compact continuum emission in IRAS F00188−0856 and IRAS F01298−0744, accounting for ∼10% of the flux density measured on arcsecond scales. The nondetection in IRAS F00091−0738 and the lower limit on the intrinsic 8.4 GHz brightness temperature of 10 6.1 K in IRAS F01298−0744 yield no conclusive evidence of AGN-driven radio emission, whereas the measurement of 10 7.8 K in IRAS F00188−0856 confirms an AGN origin. Thus, the mid-infrared AGN classification remains robust, with at least one object exhibiting compact radio emission indicative of AGN activity. We further investigate the high-frequency spectral steepening observed in all three galaxies. In each case, this steepening arises from spectral aging in diffuse kiloparsec-scale emission, which is resolved out by the VLBA observations. One possible explanation for the steepening of the sample is merger-induced particle acceleration. IRAS F00188−0856 exhibits a peaked radio spectrum, characteristic of a young radio source, with the high-frequency steepening attributable to this AGN activity. Consequently, the spectral steepening at high frequencies arises from particles accelerated by merger dynamics or AGN activity.}, archive = {J_ApJ}, author = {Takayuki J. Hayashi and Yoshiaki Hagiwara and Masatoshi Imanishi}, doi = {10.3847/1538-4357/ade9ab}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {85}, shortjournal = {The Astrophys. J.}, title = {Origin of radio emission in three nearby ultraluminous infrared galaxies with signatures of luminous buried active galactic nuclei}, volume = {989}, year = {2025}, }
• (2025). NuSTAR detection of an absorption feature in ESP 39607: Evidence for an ultrafast inflow?. ApJ, 989(1), 84. (www)

  @article{ , abstract = {We report the serendipitous discovery of an absorption feature at 4.8 keV in the NuSTAR spectra of ESP 39607, a Seyfert 2 galaxy at z = 0.201, observed in 2023 May and 2024 August. The feature is detected in both observations with individual significance levels between 2 σ and 3 σ , computed with multiple statistical methods. The combined probability of detecting it in both observations is ≳4 σ . The absorption feature is consistent with an ultrafast inflow (UFI) potentially associated with Fe xxv or Fe xxvi K α transitions. The inferred inflow velocity is ∼0.15–0.20 c , with an estimated launching radius of 22–89 R g , depending on the assumed iron transition and whether radiation pressure is accounted for. Photoionization modeling associates the UFI primarily with Fe xxv K α absorption, blended with a minor contribution from Fe xxvi K α . Alternative explanations, including associations with the warm-hot intergalactic medium or outflows of lighter elements, are investigated but found unlikely. If confirmed, this detection represents a rare example of a UFI, providing valuable evidence into extreme and/or nonstandard accretion processes near supermassive black holes. Follow-up observations with higher-resolution X-ray spectroscopy, such as with XMM-Newton or XRISM, will be essential to confirm the nature of this feature and better constrain the physical mechanisms driving it.}, archive = {J_ApJ}, author = {Alessandro Peca and Michael J. Koss and Roberto Serafinelli and Claudio Ricci and C. Megan Urry and Giulia Cerini and Peter G. Boorman}, doi = {10.3847/1538-4357/adea4a}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {84}, shortjournal = {The Astrophys. J.}, title = {NuSTAR detection of an absorption feature in ESP 39607: Evidence for an ultrafast inflow?}, volume = {989}, year = {2025}, }
• (2025). CO emission and absorption-line survey of the m87 nucleus using archival ALMA imaging. ApJ, 989(1), 83. (www)

  @article{ , abstract = {We present an M87 molecular line search from archival Atacama Large Millimeter/submillimeter Array imaging, covering the circumnuclear disk (CND) as well as ionized gas filaments and dusty cloud regions. We find no evidence for CO emission in the central ∼kiloparsec and place an upper limit of {M}_{{{\rm{H}}}_{2}}\lt 2.3\times 1{0}^{5} M ⊙ in the atomic gas CND region, a factor of 20× lower than previous surveys. During this search, we discovered extragalactic CO absorption lines in the J = 1−0, 2−1, and 3−2 transitions against the bright (jansky-scale) active nucleus. These CO lines are narrow (∼5 km s −1 ) and blueshifted with respect to the galaxy’s systemic velocity by −75 to −84 km s −1 . This CO absorber appears to be kinematically distinct from outflowing atomic gas seen in absorption. Low integrated opacities ranging from τ CO ∼ 0.02−0.06 km s −1 and a column density N CO ≈ (1.2 ± 0.2) × 10 15 cm −2 translate to {N}_{{{\rm{H}}}_{2}}\sim (1-2)\times 1{0}^{20} cm −2 . CO excitation temperatures spanning T ex ∼ 8–30 K do not follow local thermodynamic equilibrium (LTE) expectations, and non-LTE radex radiative transfer modeling of the CO absorber is consistent with a number density {n}_{{{\rm{H}}}_{2}}\sim 5000 cm −3 embedded in a ∼60 K environment. Taken together, the observed CO absorption lines are most consistent with a thin, pressure-confined filament seen slightly off-center from the M87 nucleus. We also explore the impact of residual telluric lines and atmospheric variability on narrow extragalactic line identification and demonstrate how bandpass calibration limitations may introduce broad but very low signal-to-noise ratio and spurious absorption and emission signatures.}, archive = {J_ApJ}, author = {Benjamin D. Boizelle and Xueyi Li and Nicholas LeVar and Sam Norcross and Benjamin J. Derieg and Jared R. Davidson and Kavin Siaw and Jonelle L. Walsh}, doi = {10.3847/1538-4357/adea52}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {83}, shortjournal = {The Astrophys. J.}, title = {CO emission and absorption-line survey of the m87 nucleus using archival ALMA imaging}, volume = {989}, year = {2025}, }
• (2025). Characterization of the transmission and generation of turbulence at interplanetary shocks. ApJ, 989(1), 82. (www)

  @article{ , abstract = {We study the transmission and characteristics of turbulent magnetohydrodynamic (MHD) fluctuations from upstream to downstream regions of interplanetary (IP) shocks using the linear mode decomposition (LMD) technique of G. P. Zank et al. We perform a superposed epoch analysis (SEA) of 84 fast-forward quasi-perpendicular shock events observed by the Wind spacecraft at 1 au. We find that the intensities of various MHD modes associated with density, velocity, and magnetic field fluctuations are enhanced by ∼4–14 times across the shock. On average, the amplitude enhancement of velocity fluctuations across the shock is smaller than that of density and magnetic fluctuations. The frequency spectra reveal that the entropy, magnetic island, and Alfvén modes are the dominant contributors to the overall density, magnetic field, and velocity fluctuations, respectively, both upstream and downstream. The SEA reveals that the downstream spectral slope of various modes closely follows a f −5/3 (or k −5/3 ) power law, but the upstream spectra are slightly flatter than the downstream curves. A steeper spectral slope downstream suggests an increased energy dissipation or a stronger turbulent cascade. These findings show the usefulness of the LMD technique to decompose turbulent fluctuations into fundamental linear MHD modes, providing a deeper understanding of turbulence upstream and downstream of IP shocks.}, archive = {J_ApJ}, author = {Sujan Prasad Gautam and Gary P Zank and Alexander Pitňa and Laxman Adhikari and Lingling Zhao and Ashok Silwal and Prashant Baruwal and Prashrit Baruwal and Monika Karki and Ismita Tasnim and Binod Adhikari}, doi = {10.3847/1538-4357/adeb86}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {82}, shortjournal = {The Astrophys. J.}, title = {Characterization of the transmission and generation of turbulence at interplanetary shocks}, volume = {989}, year = {2025}, }
• (2025). A hydrodynamical simulations-based model that connects the FRB DM–Redshift relation to suppression of the matter power spectrum via feedback. ApJ, 989(1), 81. (www)

  @article{ , abstract = {Understanding the impact of baryonic feedback on the small-scale ( k ≳ 1 h Mpc −1 ) matter power spectrum is a key astrophysical challenge, and essential for interpreting data from upcoming weak-lensing surveys, which require percent-level accuracy to fully harness their potential. Astrophysical probes, such as the kinematic and thermal Sunyaev–Zel’dovich effects, have been used to constrain feedback at large scales ( k ≲ 5 h Mpc −1 ). The sightline-to-sightline variance in the fast radio bursts (FRBs) dispersion measure (DM) correlates with the strength of baryonic feedback and offers unique sensitivity at scales up to k ∼ 10 h Mpc −1 . We develop a new simulation-based formalism in which we parameterize the distribution of DM at a given redshift, p (DM∣ z ), as a log-normal with its first two moments computed analytically in terms of cosmological parameters and the feedback-dependent electron power spectrum P ee ( k , z ). We find that the log-normal parameterization provides an improved description of the p (DM∣ z ) distribution observed in hydrodynamical simulations as compared to the standard F -parameterization. Our model robustly captures the baryonic feedback effects across a wide range of baryonic feedback prescriptions in hydrodynamical simulations, including IllustrisTNG , SIMBA , and Astrid . Leveraging simulations incorporates the redshift evolution of the DM variance by construction and facilitates the translation of constrained feedback parameters to the suppression of matter power spectrum relative to gravity-only simulations. We show that with 10 4 FRBs, the suppression can be constrained to percent-level precision at large scales and ∼10% precision at scales k ≳ 10 h Mpc −1 with prior-to-posterior 1 σ constraint width ratio ≳20.}, archive = {J_ApJ}, author = {Kritti Sharma and Elisabeth Krause and Vikram Ravi and Robert Reischke and Pranjal R. S. and Liam Connor}, doi = {10.3847/1538-4357/adeca4}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {81}, shortjournal = {The Astrophys. J.}, title = {A hydrodynamical simulations-based model that connects the FRB DM–Redshift relation to suppression of the matter power spectrum via feedback}, volume = {989}, year = {2025}, }
• (2025). Diversity of cold worlds: A near-complete spectral energy distribution for 2MASS j04151954−0935066 using JWST. ApJ, 989(1), 80. (www)

  @article{ , abstract = {We present a near-complete spectral energy distribution (SED) for an extrasolar world: the T8 brown dwarf 2MASS J04151954−0935066. Spanning from optical to mid-infrared (0.7–20.4 μ m) wavelengths, the SED for this substellar atmosphere is constructed from new James Webb Space Telescope (JWST) NIRSpec G395H ( R ∼ 2700) and Magellan Folded-port InfraRed Echellete (FIRE) echelle ( R ∼ 8000) near-infrared spectra, along with MIRI mid-infrared photometry complemented by spectra from Keck I, Infrared Telescope Facility, Magellan, AKARI, Spitzer, and photometry from various surveys and missions. The NIRSpec G395H spectrum reveals strong molecular absorptions from NH 3 , CH 4 , H 2 S, CO 2 , and H 2 O at approximately 3.00, 3.35, 3.95, 4.25, and 5.00 μ m, respectively, along with the presence of a CO absorption feature detected mainly at ∼4.6 μ m. We detect no absorption of near-infrared K i doublets in the R ∼ 8000 FIRE spectra. In the mid-infrared Infrared Spectrograph spectrum, we tentatively identify a new CO 2 feature at 14–16 μ m. The comprehensive SED allows us to empirically constrain bolometric luminosity, effective temperature, mass, and radius. Additionally, we demonstrate that the NIRSpec G395H resolution, the highest allowable by JWST, enables a precise radial velocity measurement of 47.1 ± 1.8 km s −1 for the object, in agreement with previous measurements.}, archive = {J_ApJ}, author = {Sherelyn Alejandro Merchan and Jacqueline K. Faherty and Genaro Suárez and Kelle L. Cruz and Adam J. Burgasser and Jonathan Gagné and Callie E. Hood and Eileen C. Gonzales and Daniella C. Bardalez Gagliuffi and Jolie L’Heureux and Johanna M. Vos and Adam C. Schneider and Aaron M. Meisner and Caroline Morley and J. Davy Kirkpatrick and Federico Marocco and Rocio Kiman and Charles A. Beichman and Ben Burningham and Dan Caselden and Peter R. Eisenhardt and Christopher R. Gelino and Ehsan Gharib-Nezhad and Marc J. Kuchner and Brianna Lacy and Austin Rothermich and Melanie J. Rowland and Niall Whiteford}, doi = {10.3847/1538-4357/ade3d7}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {80}, shortjournal = {The Astrophys. J.}, title = {Diversity of cold worlds: A near-complete spectral energy distribution for 2MASS j04151954−0935066 using JWST}, volume = {989}, year = {2025}, }
• (2025). The HST–Gaia near-infrared astrometric reference frame near the milky way galactic center. ApJ, 989(1), 79. (www)

  @article{ , abstract = {We present the first high-precision proper-motion catalog, tied to the International Celestial Reference System (ICRS), of infrared astrometric reference stars within R ≤ 25″ (1 pc) of the central supermassive black hole at the Galactic center (GC). This catalog contains ∼2900 sources in a highly extinguished region that is inaccessible via Gaia. New astrometric measurements are extracted from Hubble Space Telescope (HST) observations (14 epochs, 2010–2023) and transformed into the ICRS using 40 stars in common with Gaia-DR3. We implement a new method for modeling proper motions via Gaussian processes that accounts for systematic errors, greatly improving measurement accuracy. Proper-motion and position measurements reach precisions of ∼0.03 mas yr −1 and ∼0.11 mas, respectively, representing a factor of ∼20 improvement over previous ICRS proper-motion catalogs in the region. These measurements define a novel HST–Gaia reference frame that is consistent with Gaia-CRF3 to within 0.025 mas yr −1 in proper motion and 0.044 mas in position, making it the first ICRS-based reference frame precise enough to probe the distribution of extended mass within the orbits of stars near SgrA*. In addition, HST-Gaia provides an independent test of the radio measurements of stellar masers that form the basis of current GC reference frames. We find that the HST–Gaia and radio measurements are consistent to within 0.041 mas yr −1 in proper motion and 0.54 mas in position at 99.7% confidence. Gaia-DR4 is expected to reduce the HST–Gaia reference-frame uncertainties by another factor of ∼2, further improving the reference frame for dynamical studies.}, archive = {J_ApJ}, author = {Matthew W. Hosek and Tuan Do and Gregory D. Martinez and Rebecca Lewis-Merrill and Andrea M. Ghez and Jessica R. Lu and Shoko Sakai and Jay Anderson}, doi = {10.3847/1538-4357/ade803}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {79}, shortjournal = {The Astrophys. J.}, title = {The HST–Gaia near-infrared astrometric reference frame near the milky way galactic center}, volume = {989}, year = {2025}, }
• (2025). Modeling the high-brightness state of the recurrent nova t CrB as an enhanced mass-transfer event. ApJ, 989(1), 78. (www)

  @article{ , abstract = {T Coronae Borealis is the nearest symbiotic recurrent nova. Twice in the last two centuries, in 1866 and 1946, the accreted material ignited on the surface of the white dwarf via runaway thermonuclear fusion reactions and produced a nova eruption. Both eruptions occurred approximately midway through a transient state of high luminosity. A possible explanation of such a state is a dwarf-nova-like outburst, which may arise from a transient increase in the mass-transfer rate of the donor star. We simulate the response of an accretion disk to an event of enhanced mass-transfer that is “interrupted” by a pre-eruption dip associated with the convective phase leading to the thermonuclear runaway. We model the resulting optical light curve using the parameters of the T CrB binary. Our model represents the first attempt to reproduce the transient high-accretion state. The observed brightening can be satisfactorily reproduced by models of an accretion disk with a viscosity parameter α = 3, an event of enhanced mass-transfer with a duration of Δ t = 15 yr, and quiescent and high-state mass-transfer rates of 2.0 × 10 −9 M ⊙ yr −1 and 1.9 × 10 −7 M ⊙ yr −1 , respectively, while the pre-eruption dip can be reproduced by the small , accelerated expansion of the inner disk's radius, at an average velocity of 0.02 km s −1 . Our model is also capable of reproducing the observed changes in color of T CrB throughout the transient event.}, archive = {J_ApJ}, author = {Wagner Schlindwein and Raymundo Baptista and Gerardo Juan Manuel Luna}, doi = {10.3847/1538-4357/ade98c}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {78}, shortjournal = {The Astrophys. J.}, title = {Modeling the high-brightness state of the recurrent nova t CrB as an enhanced mass-transfer event}, volume = {989}, year = {2025}, }
• (2025). Calibrating the DMIGM–z relation using host galaxy properties of fast radio bursts. ApJ, 989(1), 77. (www)

  @article{ , abstract = {Fast radio bursts (FRBs) are extragalactic radio transients that offer valuable insight into the intergalactic medium (IGM). However, the dispersion measure (DM) contributed by the IGM (DM IGM ) is degenerate with that from the host galaxy (DM host ), necessitating calibration of the DM IGM − z relation for cosmological applications. As DM host is expected to correlate with host galaxy properties, it is feasible to estimate DM host from observable host characteristics. In this study, we conduct spectral energy distribution and Sérsic model fittings to derive the parameters of FRB host galaxies. Then, we examine the correlations between the excess dispersion measure (DM exc ) and host galaxy parameters, including star formation rate, stellar mass, specific star formation rate (sSFR), inclination angle, and projected area. A tight correlation between DM exc and sSFR is found. This correlation is utilized to estimate DM host of FRBs, providing a method to calibrate the DM IGM – z relation. This approach leads to a notable improvement in calibration performance.}, archive = {J_ApJ}, author = {Rui-Nan Li and Ke Xu and Dao-Hong Gao and Qin Wu and Shuang-Xi Yi and Fa-Yin Wang}, doi = {10.3847/1538-4357/adeb72}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {77}, shortjournal = {The Astrophys. J.}, title = {Calibrating the DMIGM–z relation using host galaxy properties of fast radio bursts}, volume = {989}, year = {2025}, }
• (2025). The effect of weak cosmic-ray heating events on the desorption of h2. ApJ, 989(1), 76. (www)

  @article{ , abstract = {The typical amount of molecular hydrogen (H 2 ) in interstellar ices is not known, but significant freeze-out of H 2 on dust grains is not expected. However, chemical models ubiquitously predict large amounts of H 2 freeze-out in dense cloud conditions, and specialized treatments are needed to control the H 2 population on grains. Here we present a numerical desorption model where the effect of weak heating events induced by cosmic rays (CRs) that heat grains to temperatures of a few tens of kelvin at high frequencies is included, improving upon earlier desorption models that only consider strong heating events (maximum grain temperature close to 100 K) that occur at a low frequency. A temperature of a few tens of kelvin is high enough to induce efficient desorption of H 2 , but we find that even the weak heating events do not occur often enough to lead to significant H 2 desorption. Taking the weak heating events into account does affect the predicted abundances of other lightly bound species, but the effect is restricted to low column densities. We make here the canonical assumption that the grains are spherical with a radius of 0.1 μ m. It is conceivable that in the case of a grain size distribution, weak heating events could provide a boost to H 2 desorption coming off small grains, which are the most numerous. Further studies are still required to better quantify the role of CRs in the desorption of H 2 and other weakly bound species.}, archive = {J_ApJ}, author = {Olli Sipilä and Kedron Silsbee and Naomi Carbajal and Paola Caselli and Marco Padovani}, doi = {10.3847/1538-4357/adec8f}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {76}, shortjournal = {The Astrophys. J.}, title = {The effect of weak cosmic-ray heating events on the desorption of h2}, volume = {989}, year = {2025}, }
• (2025). The dual nature of GHZ9: Coexisting active galactic nuclei and star formation activity in a remote X-ray source at z = 10.145. ApJ, 989(1), 75. (www)

  @article{ , abstract = {We present James Webb Space Telescope (JWST)/NIRSpec PRISM spectroscopic characterization of GHZ9 at z = 10.145 ± 0.010, currently the most distant source detected by the Chandra X-ray Observatory. The spectrum reveals several UV high-ionization lines, including C II , Si IV , N IV ], C IV , He II , O III ], N III ], and C III ]. The prominent rest-frame equivalent widths (EW(C IV ) ≃ 65 Å, EW(O III ]) ≃ 28 Å, and EW(C III ]) ≃ 48 Å) show the presence of a hard active galactic nucleus (AGN) radiation field, while line ratio diagnostics are consistent with either AGN or star formation as the dominant ionizing source. GHZ9 is nitrogen-enriched (6–9.5 (N/O) ⊙ ), carbon-poor (0.2–0.65 (C/O) ⊙ ), metal-poor ( Z = 0.01–0.1 Z ⊙ ), and compact (<106 pc), similarly to GN-z11, GHZ2, and recently discovered N-enhanced high redshift objects. We exploited the newly available JWST/NIRSpec and NIRCam data set to perform an independent analysis of the Chandra data confirming that GHZ9 is the most likely JWST source associated with X-ray emission at 0.5–7 keV. Assuming a spectral index Γ = 2.3 (1.8), we estimate a black hole (BH) mass of 1.60 ± 0.31 (0.48 ± 0.09) × 10 8 M ⊙ , which is consistent either with Eddington-accretion onto heavy (≥10 6 M ⊙ ) BH seeds formed at z = 18 or super-Eddington accretion onto a light seed of ∼10 2 –10 4 M ⊙ at z = 25. The corresponding BH-to-stellar mass ratio M BH / M star = 0.33 ± 0.22 (0.10 ± 0.07), with a stringent limit >0.02, implies an accelerated growth of the BH mass with respect to the stellar mass. GHZ9 is the ideal target to constrain the early phases of AGN–galaxy coevolution with future multifrequency observations.}, archive = {J_ApJ}, author = {Lorenzo Napolitano and Marco Castellano and Laura Pentericci and Cristian Vignali and Roberto Gilli and Adriano Fontana and Paola Santini and Tommaso Treu and Antonello Calabrò and Mario Llerena and Enrico Piconcelli and Luca Zappacosta and Sara Mascia and Roberta Tripodi and Pablo Arrabal Haro and Pietro Bergamini and Tom J. L. C. Bakx and Mark Dickinson and Karl Glazebrook and Alaina Henry and Nicha Leethochawalit and Giovanni Mazzolari and Emiliano Merlin and Takahiro Morishita and Themiya Nanayakkara and Diego Paris and Simonetta Puccetti and Guido Roberts-Borsani and Sofia Rojas Ruiz and Piero Rosati and Eros Vanzella and Fabio Vito and Benedetta Vulcani and Xin Wang and Ilsang Yoon and Jorge A. Zavala}, doi = {10.3847/1538-4357/ade706}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {75}, shortjournal = {The Astrophys. J.}, title = {The dual nature of GHZ9: Coexisting active galactic nuclei and star formation activity in a remote X-ray source at z = 10.145}, volume = {989}, year = {2025}, }
• (2025). The TeV spectral bump of cosmic-ray protons and helium nuclei: The role of nearby supernova remnants. ApJ, 989(1), 74. (www)

  @article{ , abstract = {The existence of nearby discrete cosmic-ray (CR) sources can lead to many interesting effects on the observed properties of CRs. Recent measurements of CRs with the CALET and the DAMPE experiments have revealed a bump-like new feature in the proton and helium spectra in the energy range ∼(1–100) TeV n −1 . The origin of the feature is not clearly understood. In this paper, considering an improved and more detailed analysis than previous works, and using updated age and distance estimates of nearby supernova remnants (SNRs) along with an energy-dependent escape process for CRs from the remnants, we show that the spectral bump can be explained by the contribution of CRs from the nearby SNRs, in particular the Vela remnant. We also show that the contribution from the nearby remnants agrees well with the observed spectra of the heavier CR elements from carbon to iron, as well as with the measured all-particle CR spectrum beyond the knee region when combined with a background flux of CRs originating from distant SNRs.}, archive = {J_ApJ}, author = {Sourav Bhadra and Satyendra Thoudam and Biman B. Nath and Prateek Sharma}, doi = {10.3847/1538-4357/ade796}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {74}, shortjournal = {The Astrophys. J.}, title = {The TeV spectral bump of cosmic-ray protons and helium nuclei: The role of nearby supernova remnants}, volume = {989}, year = {2025}, }
• (2025). The connection between galaxy mergers, star formation, and active galactic nuclei activity in the HSC-SSP. ApJ, 989(1), 73. (www)

  @article{ , abstract = {Internal gas inflows driven by galaxy mergers are considered to enhance star formation rates (SFRs), fuel supermassive black hole growth, and stimulate active galactic nuclei (AGNs). However, quantifying these phenomena remains a challenge, due to difficulties both in classifying mergers and in quantifying galaxy and AGN properties. We quantitatively examine the merger–SFR–AGN connection using Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) galaxies using novel methods for both galaxy classification and property measurements. Mergers in HSC-SSP observational images are identified through fine-tuning Zoobot, a pretrained deep representation learning model, using images and labels based on the Galaxy Cruise project. We use galaxy and AGN properties that were produced by fitting Galaxy and Mass Assembly spectra using the spectral energy distribution fitting code P ro S pect , which fits panchromatically across the far-ultraviolet through far-infrared wavelengths and obtains galaxy and AGN properties simultaneously. Small differences are seen in SFR and AGN activity between mergers and controls, with ΔSFR = −0.009 ± 0.003 dex, Δ f AGN = −0.010 ± 0.033 dex, and Δ L AGN = 0.002 ± 0.025 dex. After further visual purification of the merger sample, we find ΔSFR = −0.033 ± 0.014 dex, Δ f AGN = −0.024 ± 0.170 dex, and Δ L AGN = 0.019 ± 0.129 dex for pairs, and ΔSFR = −0.057 ± 0.024 dex, Δ f AGN = 0.286 ± 0.270 dex, and Δ L AGN = 0.329 ± 0.195 dex for postmergers. These numbers suggest secular processes being an important driver for star formation and AGN activity, and present a cautionary tale when using longer-timescale tracers.}, archive = {J_ApJ}, author = {Kiyoaki Christopher Omori and Connor Bottrell and Sabine Bellstedt and Aaron S. G. Robotham and Hassen M. Yesuf and Andy D. Goulding and Marcin Sawicki and Tohru Nagao and Tsutomu T. Takeuchi}, doi = {10.3847/1538-4357/ade989}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {73}, shortjournal = {The Astrophys. J.}, title = {The connection between galaxy mergers, star formation, and active galactic nuclei activity in the HSC-SSP}, volume = {989}, year = {2025}, }
• (2025). Type ia supernova progenitors and surviving companions within the symbiotic channel. ApJ, 989(1), 72. (www)

  @article{ , abstract = {The symbiotic channel of Type Ia supernovae progenitors is crucial for explaining the observed circumstellar material in some Type Ia supernovae. While extensive numerical and observational efforts have been dedicated to exploring their progenitor systems, limited emphasis has been placed on studying the surviving companions arising from the symbiotic channel. In this paper, we present a numerical study of symbiotic systems using MESA simulated stars as potential Type Ia supernova progenitors. We conduct 1260 binary stellar evolution simulations, over a wide range of parameters, incorporating the optically thick wind model developed by I. Hachisu et al., and predict the postimpact evolution of these surviving companions. We classify four types of progenitor systems based on the evolutionary stage of the companion at the onset of the explosion: red giant companions, with or without a prior helium flash event, and asymptotic giant branch companions, with or without the thermal pulsing phase. After the supernova impact, a blue dwarf star with either a helium or carbon–oxygen core is left behind. However, if a small portion of the envelope (≳0.3%) remains on the core of the surviving companion, the overall postsupernova evolution may remain similar to its preexplosion state, albeit slightly fainter, making observation a challenging endeavor.}, archive = {J_ApJ}, author = {Yu-Hui Wang and Hsin-Pei Chen and Kuo-Chuan Pan}, doi = {10.3847/1538-4357/adeb71}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {72}, shortjournal = {The Astrophys. J.}, title = {Type ia supernova progenitors and surviving companions within the symbiotic channel}, volume = {989}, year = {2025}, }
• (2025). Nature of high equivalent width emitters in the epoch of reionization revealed by JWST medium-band imaging. ApJ, 989(1), 71. (www)

  @article{ , abstract = {Extreme emission line galaxies (EELGs) at high redshifts are considered key contributors to cosmic reionization at z > 6 due to their higher ionization efficiencies. We have identified 119 H β + [O iii ] emitters at z ∼ 7 selected by a flux excess in the medium-band filter F410M in the public James Webb Space Telescope Cycle-1 fields. Our emitters exhibit a wide range in rest-frame H β + [O iii ] equivalent width (EWs), 420 < EW 0 / Å < 6850 (with the median value of ∼1700 Å). Among them, 19 are EW 0 > 3000 / Å, which represent extreme populations even in the context of recent findings with JWST. They are characterized by (i) low stellar mass (∼3 × 10 7 M ⊙ ), (ii) blue colors ( β UV ∼ −2.2), and (iii) low dust attenuation ( A V ∼ 0.1 mag). We discuss the physical mechanisms responsible for the observed high rest-frame H β + [O iii ] EWs, including (1) photoionization by active galactic nucleus (AGN), (2) stellar photoionization in the vicinity of H ii regions, and (3) radiative shocks powered by outflows either from AGN or massive stars. Notably, we find 13 emitters with spatially offset H β + [O iii ] emission compared to the UV and stellar components. Given the absence of obvious signatures of actively accreting black holes, these emitters are likely under strong feedback-driven winds from massive stars. Lastly, we report a unique overdensity of EELGs in one of the observed fields. The discovery of such a “star-bursting” overdensity supports the idea that large ionizing bubbles formed around some EEGLs in the early Universe.}, archive = {J_ApJ}, author = {Kazuki Daikuhara and Takahiro Morishita and Tadayuki Kodama and Ranga-Ram Chary and Masayuki Akiyama and Jose. M. Pérez-Martínez}, doi = {10.3847/1538-4357/ade148}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {71}, shortjournal = {The Astrophys. J.}, title = {Nature of high equivalent width emitters in the epoch of reionization revealed by JWST medium-band imaging}, volume = {989}, year = {2025}, }
• (2025). Counterculture stars: Slow and retrograde stars with low-alpha disk abundances. ApJ, 989(1), 70. (www)

  @article{ , abstract = {The Milky Way is home to a thin disk that can be defined via kinematics and/or elemental abundances. The elemental abundance-defined thin disk, also called the low-alpha disk, is generally thought to comprise stars on planar, circular orbits that approximate the circular velocity curve. While this is an apt description for the majority of stars with thin-disk-like abundances, there are a number of interesting exceptions. In this analysis, we identify and investigate ∼70 stars with thin-disk-like abundances and very slow or retrograde Galactocentric azimuthal velocities. These stars could be kinematical outliers of the thin disk or elemental abundance outliers of the halo. Focusing first on the former, we introduce a number of mechanisms that could alter a thin disk orbit and cause the azimuthal velocity to become slow or retrograde. We then determine signatures for each mechanism and assess whether that mechanism is unlikely, plausible, or consistent given each star’s reported properties. We find that at least one mechanism is plausible for each star, and the mechanism with the highest number of consistent candidate stars is dynamical ejection from stellar clusters. We next discuss scenarios that could produce halo stars with thin-disk abundances, and again identify stars that could be connected to these mechanisms. With this sample, we investigate rare processes, such as binary disruption by the central supermassive black hole, while also providing a unique perspective into the chemo-dynamics and structural components of the Milky Way.}, archive = {J_ApJ}, author = {Carrie Filion and Michael S. Petersen and Danny Horta and Kathryne J. Daniel and Madeline Lucey and Adrian M. Price-Whelan}, doi = {10.3847/1538-4357/ade2d2}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {70}, shortjournal = {The Astrophys. J.}, title = {Counterculture stars: Slow and retrograde stars with low-alpha disk abundances}, volume = {989}, year = {2025}, }
• (2025). SMA and NOEMA reveal asymmetric substructure in the protoplanetary disk of IRAS 23077+6707. ApJ, 989(1), 69. (www)

  @article{ , abstract = {We present high-resolution data of IRAS 23077+6707 (“ Dracula’s Chivito ”) with the Submillimeter Array (SMA at 1.33 mm/225.5 GHz) and the Northern Extended Millimeter Array (NOEMA at 2.7 mm/111.7 GHz and 3.1 mm/96.2 GHz). IRAS 23077+6707 is a highly inclined and newly discovered protoplanetary disk, first reported in 2024. We combine SMA baselines from the compact, extended, and very extended arrays, and NOEMA baselines from its A and C configurations, and present continuum images with resolution ≲0 \mathop{.}\limits^{\unicode{x02033}} 8, which constitute the first subarcsecond resolution maps of IRAS 23077+6707. The images show extended linear emission that spans 5 \mathop{.}\limits^{\unicode{x02033}} 6–6 \mathop{.}\limits^{\unicode{x02033}} 1 as expected for a radially extended, highly inclined protoplanetary disk. Accompanied with lower-resolution data, we show that the disk has a steep spectral index, ranging from α = 3.2–3.9. We present evidence of multiple radial emission peaks and troughs in emission, which may originate in disk rings and a central cavity. We further present evidence that these radial structures are asymmetric; hosting a significant brightness asymmetry, with emission enhanced by up to 50% in the north versus the south. We discuss hypotheses about the potential origins of these features, including the possibility that IRAS 23077+6707 hosts a rare example of an eccentric protoplanetary disk, which can induce these radially asymmetric structures. We present a simple eccentric continuum model of IRAS 23077+6707, and show, for an eccentricity of e ≈ 0.26, that this can reproduce the bulk morphology of the emission.}, archive = {J_ApJ}, author = {Joshua B. Lovell and Leon Trapman and Kristina Monsch and Sean M. Andrews and Alice S. Booth and Garrett K. Keating and Takahiro Ueda and David J. Wilner}, doi = {10.3847/1538-4357/ade392}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {69}, shortjournal = {The Astrophys. J.}, title = {SMA and NOEMA reveal asymmetric substructure in the protoplanetary disk of IRAS 23077+6707}, volume = {989}, year = {2025}, }
• (2025). A multispecies atmospheric escape model with excited hydrogen and helium: Application to HD209458b. ApJ, 989(1), 68. (www)

  @article{ , abstract = {Atmospheric escape shapes exoplanet evolution and star–planet interactions, with He I 10830 Å absorption serving as a key tracer of mass loss in hot gas giants. However, transit depths vary significantly across observed systems for reasons that remain poorly understood. HD209458b, the archetypal hot-Jupiter, exhibits relatively weak He I 10830 Å and H α absorption, which has been interpreted as evidence for a high H/He ratio (98/2), possibly due to diffusive separation. To investigate this possibility and other processes that control these transit depths, we reassess excitation and de-excitation rates for metastable helium and explore the impact of diffusion processes, stellar activity, and tidal forces on the upper atmosphere and transit depths using a model framework spanning the whole atmosphere. Our model reproduces the observed He I transit depth and H α upper limit, showing strong diffusive separation. We match the observations assuming a photoelectron efficiency of 20%–40%, depending on the composition of the atmosphere, corresponding to mass-loss rates of 1.9–3 × 10 10 g s −1 . We find that the He I 10830 Å transit depth is sensitive to both stellar activity and diffusion processes, while H α is largely unaffected due to its strong dependence on Ly α excitation. These differences may help explain the system-to-system scatter seen in population-level studies of the He I line. While He I data alone may not tightly constrain mass-loss rates or temperatures, they do confirm atmospheric escape and help narrow the viable parameter space when interpreted with physically motivated models. Simultaneous observations of He I , H α , and stellar activity indicators provide powerful constraints on upper atmosphere dynamics and composition, even in the absence of full transmission spectra.}, archive = {J_ApJ}, author = {Anna Ruth Taylor and Tommi T. Koskinen and Luca Argenti and Nicholas Lewis and Chenliang Huang and Anthony Arfaux and Panayotis Lavvas}, doi = {10.3847/1538-4357/ade3c9}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {68}, shortjournal = {The Astrophys. J.}, title = {A multispecies atmospheric escape model with excited hydrogen and helium: Application to HD209458b}, volume = {989}, year = {2025}, }
• (2025). McFACTS III: Compact binary mergers from active galactic nucleus disks over an entire synthetic universe. ApJ, 989(1), 67. (www)

  @article{ , abstract = {The active galactic nucleus (AGN) channel for the formation of binary black hole (BBH) mergers has been previously studied as a potential formation channel for the merging compact binaries observed by the LIGO–Virgo–KAGRA (LVK) scientific collaboration. The first two papers in this series explored the McFACTS code for the evolution of black hole orbits in AGN accretion disks for individual galaxy models and described the characteristics of predicted BBH populations in realizations of those models (such as the correlation between mass ratio and aligned spin). In this work, we explore the impact of the properties of AGN host galaxies and assume an AGN lifetime and cosmological model for the density of AGN in a universe like our own. By sampling from an inferred population of AGN, we marginalize over galaxy mass to predict a population of BBH mergers observable by modern ground-based gravitational-wave observatories. We find that for reasonable assumptions, AGN disk environments may account for massive BBH mergers such as GW190521 and GW190929_012149. We find that the majority of observable BBH mergers from our simulation are expected to originate in galaxies with a supermassive black hole between 10 7 M ⊙ and 10 9.4 M ⊙ . We also find that if hierarchical mergers from AGN disks account for a substantial part of the LVK population, our current models require an AGN lifetime of 0.5–2.5 Myr.}, archive = {J_ApJ}, author = {Vera Delfavero and K. E. Saavik Ford and Barry McKernan and Harrison E. Cook and Kaila Nathaniel and Jake Postiglione and Shawn Ray and Emily McPike and Richard O’Shaughnessy}, doi = {10.3847/1538-4357/ade4c1}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {67}, shortjournal = {The Astrophys. J.}, title = {McFACTS III: Compact binary mergers from active galactic nucleus disks over an entire synthetic universe}, volume = {989}, year = {2025}, }
• (2025). Modeling the mass distribution and gravitational potential of nearby disk galaxies: Implications for the interstellar medium dynamical equilibrium. ApJ, 989(1), 66. (www)

  @article{ , abstract = {We characterize stellar, gas, and dark matter mass distributions for 17 nearby massive disk galaxies from the PHANGS sample. This allows us to compute the gravitational potential that vertically confines the interstellar gas and determines its equilibrium scale height and weight. We first combine dynamical mass constraints from existing CO and H i rotation curves, together with stellar and gas mass estimates from near-infrared, CO, and H i data. These estimates incorporate current best practices in modeling stellar mass-to-light ratios and CO-to-H 2 conversion factor variations. Then, we fit joint stellar–gas–dark matter mass models to the rotation curves, adopting the classic maximal disk assumption to account for remaining zero-point uncertainties on the stellar mass-to-light ratio. After obtaining three-component radial mass profiles, we calculate the vertical equilibrium gas scale height and interstellar medium (ISM) weight in the combined gravitational potential. We find the gas scale height H gas increases from ≲100 pc in the inner disks to >500 pc at large radii, consistent with observations of our Galaxy and other edge-on galaxies. The gas weight is dominated by stellar gravity at small radii, but the gas and dark matter gravity often become important beyond 3–6 times the stellar disk radial scale length. Both our gas scale height and weight estimates are dependent on the treatment of stellar disk scale height H ⋆ , with H gas varying by 30%–40% when H ⋆ varies by a factor of 3. The relationship between our refined ISM weight estimates and local star formation surface density generally agrees with previous observations and predictions from theory and simulations.}, archive = {J_ApJ}, author = {Vivek Vijayakumar and Jiayi Sun and Eve C. Ostriker and Enrico M. Di Teodoro and Konstantin Haubner and Chang-Goo Kim and Adam K. Leroy and Miguel Querejeta}, doi = {10.3847/1538-4357/ade800}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {66}, shortjournal = {The Astrophys. J.}, title = {Modeling the mass distribution and gravitational potential of nearby disk galaxies: Implications for the interstellar medium dynamical equilibrium}, volume = {989}, year = {2025}, }
• (2025). Leveraging machine learning for accurate and fast stellar mass estimation of galaxies. ApJ, 989(1), 65. (www)

  @article{ , abstract = {Unveiling the evolutionary history of galaxies necessitates a precise understanding of their physical properties. Traditionally, astronomers achieve this through spectral energy distribution (SED) fitting. However, this approach can be computationally intensive and time-consuming, particularly for large data sets. This study investigates the viability of machine learning (ML) algorithms as an alternative to traditional SED fitting for estimating stellar masses in galaxies. We compare a diverse range of unsupervised and supervised learning approaches, including prominent algorithms such as K-means, HDBSCAN, Parametric t-Distributed Stochastic Neighbor Embedding (Pt-SNE), principal component analysis, Random Forest, and self-organizing maps (SOM) against the well-established LePhare code, which performs SED fitting as a benchmark. We train various ML algorithms using simple model SEDs in photometric space, generated with the BC03 code. These trained algorithms are then employed to estimate the stellar masses of galaxies within a subset of the COSMOS survey data set. The performance of these ML methods is subsequently evaluated and compared with the results obtained from LePhare, focusing on both accuracy and execution time. Our evaluation reveals that ML algorithms can achieve comparable accuracy to LePhare while offering significant speed advantages (1000–100,000 times faster). K-means and HDBSCAN emerge as top performers among our selected ML algorithms. Supervised learning algorithms like Random Forest and manifold learning techniques such as Pt-SNE and SOM also show promising results. These findings suggest that ML algorithms hold significant promise as a viable alternative to traditional SED-fitting methods for estimating the stellar masses of galaxies.}, archive = {J_ApJ}, author = {Vahid Asadi and Akram Hasani Zonoozi and Hosein Haghi and Fatemeh Abedini and Atousa Kalantari and Marziye Jafariyazani and Nima Chartab}, doi = {10.3847/1538-4357/ade805}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {65}, shortjournal = {The Astrophys. J.}, title = {Leveraging machine learning for accurate and fast stellar mass estimation of galaxies}, volume = {989}, year = {2025}, }
• (2025). The unreasonable effectiveness of the nΣv approximation. ApJ, 989(1), 64. (www)

  @article{ , abstract = {In kinetic theory, the classic n Σ v approach calculates the rate of particle interactions from local quantities: the number density of particles n , the cross section Σ, and the average relative speed v . In stellar dynamics, this formula is often applied to problems in collisional (i.e., dense) environments such as globular and nuclear star clusters, where blue stragglers, tidal capture binaries, binary ionizations, and microtidal disruptions arise from rare close encounters. The local n Σ v approach implicitly assumes the ergodic hypothesis, which is not well motivated for the densest star systems in the Universe. In the centers of globular and nuclear star clusters, orbits close into 1D ellipses because of the degeneracy of the potential (either Keplerian or harmonic). We find that the interaction rate in perfectly Keplerian or harmonic potentials is determined by a global quantity—the number of orbital intersections—and that this rate can be far lower or higher than the ergodic n Σ v estimate. However, we find that, in most astrophysical systems, deviations from a perfectly Keplerian or harmonic potential (due to, e.g., granularity or extended mass) trigger sufficient orbital precession to recover the n Σ v interaction rate. Astrophysically relevant failures of the n Σ v approach only seem to occur for tightly bound stars orbiting intermediate-mass black holes, or for the high-mass end of collisional cascades in certain debris disks.}, archive = {J_ApJ}, author = {Elisha Modelevsky and Nicholas C. Stone and Re’em Sari}, doi = {10.3847/1538-4357/ade878}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {64}, shortjournal = {The Astrophys. J.}, title = {The unreasonable effectiveness of the nΣv approximation}, volume = {989}, year = {2025}, }
• (2025). Rapid spectral evolution of SGR 1935+2154 during its 2022 outburst. ApJ, 989(1), 63. (www)

  @article{ , abstract = {During the 2022 outburst of SGR 1935+2154, a fast radio burst (FRB)-like event (FRB 20221014A) and X-ray activities occurred between two spin-up glitches, suggesting these glitches may connect to multiwavelength phenomenology. However, the mechanisms altering the magnetar’s magnetosphere to enable radio emission remain unclear. This study presents high-cadence Neutron Star Interior Composition Explorer and Nuclear Spectroscopic Telescope Array observations revealing spectral changes in burst and persistent emission. Hardness ratio and spectral analysis reveal significant changes during an “intermediate flare” 2.5 hr before FRB 20221014A. This 40 s flare, releasing >(6.3 ± 0.2) × 10 40 erg, coincides with a rapid spectral softening in both burst and persistent emission, and a notable decrease in the burst occurrence rate. The intermediate flare is bright enough to be detected if placed at a few megaparsecs, and would appear as a fast X-ray transient. This implies that the connection between magnetar X-ray activity and FRBs can be observed in the local Universe. Postflare burst spectra peak near 5 keV, resembling the characteristics of the FRB-associated X-ray burst of 2020. Such change persisted for a few hours, implying magnetospheric evolution on similar timescales. However, no radio emission was detected from postflare bursts, suggesting that FRB emission requires conditions beyond peculiar short bursts. The burst waiting times exhibit a broken power-law distribution, likely resulting from contamination by enhanced persistent emission. Although the bursts appear randomly distributed in the spin phase, the hardness ratio profile as a function of spin phase follows that of the persistent emission, indicating that X-ray bursts originate at low altitudes.}, archive = {J_ApJ}, author = {Chin-Ping Hu and Zorawar Wadiasingh and Wynn C. G. Ho and Matthew G. Baring and George A. Younes and Teruaki Enoto and Sebastien Guillot and Tolga Güver and Marlon L. Bause and Rachael Stewart and Alex Van Kooten and Chryssa Kouveliotou}, doi = {10.3847/1538-4357/adea4e}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {63}, shortjournal = {The Astrophys. J.}, title = {Rapid spectral evolution of SGR 1935+2154 during its 2022 outburst}, volume = {989}, year = {2025}, }
• (2025). Influence of solar cycle on magnetohydrodynamic turbulent modes at 1 au. ApJ, 989(1), 62. (www)

  @article{ , abstract = {We study the effect of the solar cycle on various magnetohydrodynamic (MHD) fluctuation modes using the linear mode decomposition technique developed by G. P. Zank et al. We decompose various MHD modes, including propagating modes: Alfvén (forward and backward), fast (forward and backward), and slow (forward and backward) modes, as well as nonpropagating structures: entropy and magnetic island modes, from solar wind intervals during both the minimum and maximum phases of solar cycle 23. We find that the amplitudes of different modes corresponding to fluctuations in density, magnetic field, and velocity vary over the solar cycle, with larger amplitudes observed during the solar maximum compared to the solar minimum. The fluctuating energy of these modes is ∼1.5–4.5 times larger during the solar maximum. The frequency spectrum shows that the entropy mode exhibits the largest fluctuating power among density fluctuations, surpassing the contributions of fast and slow magnetosonic modes during both solar maximum and minimum intervals. For magnetic field fluctuations, the dominant contributors are the magnetic island mode, followed by the Alfvén modes. The Alfvén modes dominate the overall velocity fluctuations. This study provides observational evidence for the influence of the solar cycle on linear MHD modes.}, archive = {J_ApJ}, author = {Sujan Prasad Gautam and Gary P. Zank and Laxman Adhikari and Alexander Pitňa and Ashok Silwal}, doi = {10.3847/1538-4357/adee86}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {62}, shortjournal = {The Astrophys. J.}, title = {Influence of solar cycle on magnetohydrodynamic turbulent modes at 1 au}, volume = {989}, year = {2025}, }
• (2025). Nature or nurture: LMC-like dust in the solar metallicity galaxy m31. ApJ, 989(1), 61. (www)

  @article{ , abstract = {Using the Hubble Space Telescope/Space Telescope Imaging Spectrograph, ultraviolet (UV) extinction curves have been measured in M31 along 13 new sight lines, increasing the M31 sample to 17. This sample covers a wide area of M31, having galactocentric distances of 5–16 kpc, enabling the analysis of UV extinction curve variations over a large region of an external galaxy similar to the Milky Way with global galactic characteristics such as metallicity for the first time. No correlation is found between the extinction parameters and galactocentric distance, which might be expected if there is a radial metallicity gradient in M31. Most of the new UV extinction curves presented here are significantly different from the average extinction curves of the Milky Way, Large Magellanic Cloud (LMC), and Small Magellanic Cloud (SMC), but the average M31 extinction curve is similar to the average extinction curve in the 30 Dor region of the LMC. The wide range of extinction curves seen in each individual Local Group galaxy suggests that global galactic properties such as metallicity may be less important than the local environmental conditions, such as density, UV radiation field, and shocks along each sight line. The combined behavior of the Milky Way, LMC, SMC, and now M31 UV extinction curves supports the idea that there is a family of curves in the Local Group with overlapping dust grain properties between different galaxies.}, archive = {J_ApJ}, author = {Geoffrey C. Clayton and Petia Yanchulova Merica-Jones and Karl D. Gordon and Marjorie Decleir and Claire E. Murray and Ralph Bohlin and Luciana Bianchi and Philip Massey and Michael J. Wolff}, doi = {10.3847/1538-4357/adef45}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {61}, shortjournal = {The Astrophys. J.}, title = {Nature or nurture: LMC-like dust in the solar metallicity galaxy m31}, volume = {989}, year = {2025}, }
• (2025). Investigating the dainotti relation in gamma-ray bursts through multipolar electromagnetic radiation. ApJ, 989(1), 60. (www)

  @article{ , abstract = {The Dainotti relation empirically connects the isotropic plateau luminosity ( L X ) in gamma-ray bursts (GRBs) and X-ray afterglows to the rest-frame time at which the plateau ends ( {T}_{a}^{* } ), enabling both the standardization of GRBs and their use as cosmological probes. However, the precise physical mechanisms underlying this correlation remain an active area of research. Although magnetars, highly magnetized neutron stars, have been proposed as central engines powering GRB afterglows, traditional dipole spin-down radiation models fail to account for the full diversity of observed behaviors. This limitation necessitates a more comprehensive framework. We propose that multipolar magnetic field emissions from magnetars offer a plausible explanation for the Dainotti relation. Unlike simple dipole fields, higher-order multipolar configurations enable more complex energy dissipation processes. The coexistence of multiple components can plausibly explain the range of afterglow decay indices found from a sample of 238 GRBs with plateau features from the Swift-X-Ray Telescope database up to the end of 2024 December, the majority of which deviate from the dipolar prediction of α = −2, and more crucially, the spin-down physics yields a link between L X and {T}_{a}^{* } in a way that preserves the Dainotti correlation with a slope of b = −1, independent of the specific multipole order. Moreover, we find that the inclusion of higher-order multipoles can explain the range of plateau energies found in the Dainotti relations. Thus, a unified picture emerges in which multipolar fields are able to reproduce both the slope and the normalization of the correlation.}, archive = {J_ApJ}, author = {Emre S. Yorgancioglu and Daban Mohammed Saeed and Rahim Moradi and Yu Wang}, doi = {10.3847/1538-4357/adef47}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {60}, shortjournal = {The Astrophys. J.}, title = {Investigating the dainotti relation in gamma-ray bursts through multipolar electromagnetic radiation}, volume = {989}, year = {2025}, }
• (2025). First evidence for a quasiperiodic oscillation triplet and its relativistic precession origin in RE j1034+396. ApJ, 989(1), 59. (www)

  @article{ , abstract = {Quasiperiodic oscillations (QPOs) in active galactic nuclei (AGNs) provide a powerful tool for probing the structure of the innermost accretion flow and corona around supermassive black holes. RE J1034+396, the most prominent AGN known to host an X-ray QPO, exhibits both short-term and long-term QPO evolution, offering a unique opportunity to investigate accretion disk and corona physics through its temporal behavior. We report a possible long-term (∼92.2 days) cyclic evolution of the QPO in RE J1034+396, joining the detected QPO (∼3730 s) and its short-term (∼17 ks) modulation to form a possible QPO triplet, which is potentially the first such structure identified in an AGN. By applying the relativistic precession model to the QPO triplet, we constrain the black hole mass to 1.{7}_{-0.8}^{+0.9}\times 1{0}^{6}\,{M}_{\odot } , consistent with independent estimates, and find a low dimensionless black hole spin of 0.01{7}_{-0.012}^{+0.028} . We propose an exploratory model that involves a quasiperiodic ultrafast outflow (UFO) within the framework of the relativistic precession model, explaining the QPO lag reversal, the modulation of hard-band QPO amplitude by soft-band flux, and the long-term evolution of timing properties. Supporting evidence includes blueshifted emission and absorption lines indicating a strong UFO at ∼0.3 c . This work provides new insights into the inner regions of AGN accretion disks and motivates further efforts in both numerical modeling and high-cadence timing observations.}, archive = {J_ApJ}, author = {Ruisong Xia and Yongquan Xue and Jialai Wang and Hao Liu}, doi = {10.3847/1538-4357/adf225}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {59}, shortjournal = {The Astrophys. J.}, title = {First evidence for a quasiperiodic oscillation triplet and its relativistic precession origin in RE j1034+396}, volume = {989}, year = {2025}, }
• (2025). Identifying dwarfs of MC analog GalaxiEs (ID-MAGE): The search for satellites around low-mass hosts. ApJ, 989(1), 58. (www)

  @article{ , abstract = {We present results from Identifying Dwarfs of MC Analog GalaxiEs (ID-MAGE), a survey aimed at identifying and characterizing unresolved satellite galaxies around 35 nearby LMC- and SMC-mass hosts ( D = 4−10 Mpc). We use archival DESI Legacy Survey imaging data and perform an extensive search for dwarf satellites, extending out to a radius of 150 kpc (∼ R vir ). We identify 355 candidate satellite galaxies, including 264 new discoveries. Extensive tests with injected galaxies demonstrate that the survey is complete down to M V ∼ −9.0 (assuming the distance of the host) and μ 0, V ∼ 26 mag arcsec −2 (assuming an n = 1 Sérsic profile). We perform consistent photometry, via Sérsic profile fitting, on all candidates and have initiated a comprehensive follow-up campaign to confirm and characterize candidates. Through a systematic visual inspection campaign, we classify the top candidates as high-likelihood satellites. On average, we find 4.0 ± 1.4 high-likelihood candidate satellites per LMC-mass host and 2.1 ± 0.6 per SMC-mass host, which is within the range predicted by cosmological models. We use this sample to establish upper and lower estimates on the satellite luminosity function of LMC-/SMC-mass galaxies. ID-MAGE nearly triples the number of low-mass galaxies surveyed for satellites with well-characterized completeness limits, providing a unique data set to explore small-scale structure and dwarf galaxy evolution around low-mass hosts in diverse environments.}, archive = {J_ApJ}, author = {Laura Congreve Hunter and Burçİn Mutlu-Pakdİl and David J. Sand and Paul Bennet and Donghyeon J. Khim and Denija Crnojević and Amandine Doliva-Dolinsky and Emmanuel Durodola and Catherine Fielder and Rowan Goebel-Bain and Michael G. Jones and Ananthan Karunakaran and Kristine Spekkens and Dennis Zaritsky}, doi = {10.3847/1538-4357/ade9a4}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {58}, shortjournal = {The Astrophys. J.}, title = {Identifying dwarfs of MC analog GalaxiEs (ID-MAGE): The search for satellites around low-mass hosts}, volume = {989}, year = {2025}, }
• (2025). Limits on the 21 cm power spectrum at z = 6.5–7.0 from murchison widefield array observations. ApJ, 989(1), 57. (www)

  @article{ , abstract = {This paper presents the spherically averaged 21 cm power spectrum derived from Epoch of Reionization (EoR) observations conducted with the Murchison Widefield Array (MWA). The analysis uses EoR0-field data, centered at (R.A. = 0 h , decl. = −27 ∘ ), collected between 2013 and 2023. Building on the improved methodology described in C. M. Trott et al. (2024), we incorporate additional data quality control techniques introduced in C. D. Nunhokee (2020). We report the lowest-power-level limits on the EoR power spectrum at redshifts z = 6.5, z = 6.8, and z = 7.0. These power levels, measured in the east–west polarization, are (30.2) 2 mK 2 at k = 0.18 h Mpc −1 , (31.2) 2 mK 2 at k = 0.18 h Mpc −1 , and (39.1) 2 mK 2 at k = 0.21 h Mpc −1 , respectively. The total integration time amounts to 268 hr. These results represent the deepest upper limits achieved by the MWA to date and provide the first evidence of the heated intergalactic medium at redshifts z = 6.5 to 7.0.}, archive = {J_ApJ}, author = {C. D. Nunhokee and D. Null and C. M Trott and N. Barry and Y. Qin and R. B. Wayth and J. L. B. Line and C. H. Jordan and B. Pindor and J. H. Cook and J. Bowman and A. Chokshi and J. Ducharme and K. Elder and Q. Guo and B. Hazelton and W. Hidayat and T. Ito and D. Jacobs and E. Jong and M. Kolopanis and T. Kunicki and E. Lilleskov and M. F. Morales and J. C. Pober and A. Selvaraj and R. Shi and K. Takahashi and S. J. Tingay and R. L. Webster and S. Yoshiura and Q. Zheng}, doi = {10.3847/1538-4357/adda45}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {57}, shortjournal = {The Astrophys. J.}, title = {Limits on the 21 cm power spectrum at z = 6.5–7.0 from murchison widefield array observations}, volume = {989}, year = {2025}, }
• (2025). ALMASOP. a rotating feature rich in complex organic molecules in a protostellar core. ApJ, 989(1), 56. (www)

  @article{ , abstract = {Interstellar complex organic molecules (COMs) in solar-like young stellar objects (YSOs), particularly within protostellar disks, are of significant interest owing to their potential connection to prebiotic chemistry in emerging planetary systems. We report the discovery of a rotating feature enriched in COMs, including CH 3 OH, CH 3 CHO, and NH 2 CHO, in the protostellar core G192.12-11.10. By constructing a YSO model, we find that the COM-rich feature is likely located within or near the boundary of the Keplerian disk. The image synthesis results suggest that additional heating mechanisms leading to a warm ring or a warm inner disk are required to reproduce the observed emission. We discuss possible origins of the COM-rich feature, particularly accretion shocks as a plausible cause for a warm ring. Additionally, molecules such as C 18 O, H 2 CO, DCS, H 2 S, and OCS exhibit distinct behavior compared to CH 3 OH, indicating a range of physical and chemical conditions within the region. The observed kinematics of H 2 S and OCS suggest that OCS resides in regions closer to the central protostar than H 2 S, consistent with previous experimental studies.}, archive = {J_ApJ}, author = {Shih-Ying Hsu and Chin-Fei Lee and Doug Johnstone and Sheng-Yuan Liu and Tie Liu and Leonardo Bronfman and Huei-Ru Vivien Chen and Somnath Dutta and David J. Eden and Naomi Hirano and Mika Juvela and Kee-Tae Kim and Yi-Jehng Kuan and Woojin Kwon and Chang Won Lee and Jeong-Eun Lee and Shanghuo Li and Sheng-Jun Lin and Chun-Fan Liu and Xunchuan Liu and J. A. López-Vázquez and Qiuyi Luo and Mark G. Rawlings and Dipen Sahu and Patricio Sanhueza and Hsien Shang and Ken'ichi Tatematsu and Yao-Lun Yang}, doi = {10.3847/1538-4357/ade7fc}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {56}, shortjournal = {The Astrophys. J.}, title = {ALMASOP. a rotating feature rich in complex organic molecules in a protostellar core}, volume = {989}, year = {2025}, }
• (2025). Search for slow bars in two barred galaxies with nuclear structures: NGC 6951 and NGC 7716. ApJ, 989(1), 55. (www)

  @article{ , abstract = {We investigate two barred galaxies with nuclear structures, NGC 6951 and NGC 7716, to examine whether they host slow bars. Using Gemini/GMOS long-slit spectroscopy, we calculate the bar pattern speed with the Tremaine–Weinberg method and detect kinematically decoupled nuclear disks in both galaxies. We also measure the bar length and strength using Pan-STARRs images and identify a nuclear ring in NGC 6951 and a nuclear bar in NGC 7716 from Hubble Space Telescope/Planetary Camera images. Our results indicate that NGC 6951 hosts a slow, long, and strong bar, which likely evolved through interactions with the dark matter halo and contributed to the formation of both the nuclear disk and ring. We also find hints of a rapidly rotating oval structure within the primary bar, although it is not clearly seen in the imaging data. In contrast, the primary bar in NGC 7716 is too weak to be classified as a barred galaxy, while its nuclear disk and nuclear bar are unusually large, possibly due to tidal interactions or the weakness of the primary bar. These findings suggest that slow bars may be more observed in galaxies with nuclear structures and highlight the often underappreciated role of galaxy interactions in bar evolution.}, archive = {J_ApJ}, author = {Yun Hee Lee and Ho Seong Hwang and Virginia Cuomo and Myeong-Gu Park and Taehyun Kim and Narae Hwang and Hong Bae Ann and Woong-Tae Kim and Hyun-Jeong Kim and Ji Yeon Seok and Jeong Hwan Lee and Yeon-Ho Choi}, doi = {10.3847/1538-4357/ade8ee}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {55}, shortjournal = {The Astrophys. J.}, title = {Search for slow bars in two barred galaxies with nuclear structures: NGC 6951 and NGC 7716}, volume = {989}, year = {2025}, }
• (2025). A luminous red optical flare and hard X-ray emission in the tidal disruption event AT 2024kmq. ApJ, 989(1), 54. (www)

  @article{ , abstract = {We present the optical discovery and multiwavelength follow-up observations of AT 2024kmq, a likely tidal disruption event (TDE) associated with a supermassive ( M BH ∼ 10 8 M ⊙ ) black hole in a massive galaxy at z = 0.192. The optical light curve of AT 2024kmq exhibits two distinct peaks: an early fast (timescale 1 day) and luminous ( M ≈ −20 mag) red peak, then a slower (timescale 1 month) blue peak with a higher optical luminosity ( M ≈ −22 mag) and featureless optical spectra. The second component is similar to the spectroscopic class of “featureless TDEs” in the literature, and during this second component we detect highly variable, luminous ( L X ≈ 10 44 erg s −1 ), and hard ( f ν ∝ ν −1.5 ) X-ray emission. Luminous (10 29 erg s −1 Hz −1 at 10 GHz) but unchanging radio emission likely arises from an underlying active galactic nucleus. The luminosity, timescale, and color of the early red optical peak can be explained by synchrotron emission, or alternatively by thermal emission from material at a large radius ( R ≈ a few × 10 15 cm). Possible physical origins for this early red component include an off-axis relativistic jet, and shocks from self-intersecting debris leading to the formation of the accretion disk. Late-time radio observations will help distinguish between the two possibilities.}, archive = {J_ApJ}, author = {Anna Y. Q. Ho and Yuhan Yao and Tatsuya Matsumoto and Genevieve Schroeder and Eric R. Coughlin and Daniel A. Perley and Igor Andreoni and Eric C. Bellm and Tracy X. Chen and Ryan Chornock and Sofia Covarrubias and Kaustav Das and Christoffer Fremling and Marat Gilfanov and K. R. Hinds and Dan Jarvis and Mansi M. Kasliwal and Chang Liu and Joseph D. Lyman and Frank J. Masci and Thomas A. Prince and Vikram Ravi and R. Michael Rich and Reed Riddle and Cassie Sevilla and Roger Smith and Jesper Sollerman and Jean J. Somalwar and Gokul P. Srinivasaragavan and Rashid Sunyaev and Jada L. Vail and Jacob L. Wise and Sol Bin Yun}, doi = {10.3847/1538-4357/ade8f2}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {54}, shortjournal = {The Astrophys. J.}, title = {A luminous red optical flare and hard X-ray emission in the tidal disruption event AT 2024kmq}, volume = {989}, year = {2025}, }
• (2025). Infant core-collapse supernovae with circumstellar interactions from KMTNet. i. luminous transitional case of KSP-SN-2022c. ApJ, 989(1), 53. (www)

  @article{ , abstract = {We present BVi multiband high-cadence observations of a Type II supernova (SN) KSP-SN-2022c from a star-forming galaxy at z ≃ 0.041 from its infant to nebular phase. Early light-curve fitting with a single power law is consistent with the first detection roughly 15 minutes after shock breakout (SBO). The SN light curves feature a rapid rise and decline across its luminous ( V ≃ –18.41 mag) peak together with a short plateau. The presence of the short plateau and rapid postpeak decline place the SN within a small group of transitional type between Type II-P and II-L subtypes. Its broad and asymmetric H profiles with large emission-to-absorption ratios and its near-peak luminosity in excess of predictions from models of SN shock cooling both point to circumstellar interactions in this SN. Early colour evolution exhibits a short-lived blueward motion in B − V within the first few days and continuous reddening in V − i , inconsistent with simple blackbody heating. Our simulations of SN light curves estimate 13 M ⊙ and 680 R ⊙ for the mass and radius of the progenitor, respectively, together with circumstellar material (CSM) of 0.73 M ⊙ to account for the excess luminosity and rapid postpeak declines. We discuss the origin of its short plateau and early colour evolution in the context of partial envelope stripping of the progenitor star and a delayed SN SBO near the edge of the CSM, respectively, as indicated by our simulations. We establish a correlation between postpeak decline rates and CSM mass in Type II SNe, highlighting that CSM interactions play a major role in shaping the postpeak evolution of transitional types.}, archive = {J_ApJ}, author = {Nan Jiang and Dae-Sik Moon and Yuan Qi Ni and Maria R. Drout and Hong Soo Park and Santiago González-Gaitán and Sang Chul Kim and Youngdae Lee and Ernest Chang}, doi = {10.3847/1538-4357/ade997}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {53}, shortjournal = {The Astrophys. J.}, title = {Infant core-collapse supernovae with circumstellar interactions from KMTNet. i. luminous transitional case of KSP-SN-2022c}, volume = {989}, year = {2025}, }
• (2025). Properties of H2O masers and their associated sources in sagittarius b2. ApJ, 989(1), 52. (www)

  @article{ , abstract = {We present high-resolution Karl G. Jansky Very Large Array observations of the 22 GHz H 2 O maser line in the extended Sagittarius B2 cloud. We detect 499 H 2 O masers across the observed velocities between −39 and 172 km s −1 . To investigate the nature of the masers, we analyze their spatial distribution and crossmatch with catalogs of H II regions and protostellar cores. 62% of masers are associated with protostellar cores and 32% with H II regions. The nature of the remaining 6% of sources was not established but is likely associated with protostellar cores. Based on the spatial extent of the groups of masers, we classify them as either outflow-associated or young stellar object (YSO)–associated. We identify 144 unique sites of maser emission: 23 are associated with H II regions and 94 with protostellar cores, of which 33 are associated with protostellar outflows and 18 with YSOs. The outflow-associated H 2 O maser emission is confined to within <2000 au of the central continuum source, despite shocked SiO emission extending over tens of thousands of astronomical units. The YSO-associated masers show a lack of detections at 5 < V rel < 30 km s −1 , which we suggest may be due to maser self-absorption. We show how H 2 O masers trace the large-scale material flow in Sgr B2 North, also seen in SiO and millimeter continuum emission. Finally, we find that protostellar cores with associated H 2 O masers tend to have brighter 3 mm continuum emission on average, although there is no strong correlation between maser brightness and continuum flux.}, archive = {J_ApJ}, author = {Nazar Budaiev and Adam Ginsburg and Ciriaco Goddi and Álvaro Sánchez-Monge and Anika Schmiedeke and Desmond Jeff and Peter Schilke and Christopher De Pree}, doi = {10.3847/1538-4357/adea3b}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {52}, shortjournal = {The Astrophys. J.}, title = {Properties of H2O masers and their associated sources in sagittarius b2}, volume = {989}, year = {2025}, }
• (2025). The hydrodynamic thermal continuum, with applications to stratified atmospheres and 1D coronal loop models. ApJ, 989(1), 51. (www)

  @article{ , abstract = {Using both analytical and numerical means, we demonstrate that linear stability analysis of a hydrodynamic stratified atmosphere or a 1D coronal loop model in nonadiabatic settings features a thermal continuum corresponding to highly localized eigenfunctions. This thermal continuum can be precomputed, involving the net heat-loss function and its partial derivatives, and is the generalization of the thermal instability introduced by E. N. Parker. We account for a thermal imbalance, directly affecting thermal instability growth rates. We present completely general equations that govern all eigenmodes, including nonadiabatically affected p - and g -modes of the stratified settings. We intend to clarify how linear thermal instability is relevant for solar loops that show spontaneous in situ condensations, and eliminate recent confusion on specific isochoric routes to linear instability alongside other thermal instability channels. The thermal continuum, previously identified as a crucial ingredient in magnetohydrodynamic eigenmode spectra for coronal loops and atmospheres, drives multithermal aspects across our Universe, such as forming solar coronal rain and prominences, or cold cloud creation in intracluster to interstellar medium environments.}, archive = {J_ApJ}, author = {Rony Keppens and Jordi De Jonghe and Adrian Kelly and Nicolas Brughmans and Hans Goedbloed}, doi = {10.3847/1538-4357/adea43}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {51}, shortjournal = {The Astrophys. J.}, title = {The hydrodynamic thermal continuum, with applications to stratified atmospheres and 1D coronal loop models}, volume = {989}, year = {2025}, }
• (2025). A next-generation exoplanet atmospheric retrieval framework for transmission spectroscopy (NEXOTRANS): Comparative characterization for WASP-39 b using JWST NIRISS, NIRSpec PRISM, and MIRI observations. ApJ, 989(1), 50. (www)

  @article{ , abstract = {The advent of JWST has marked a new era in exoplanetary atmospheric studies, offering higher-resolution data and greater precision across a broader spectral range than previous space-based telescopes. Accurate analysis of these data sets requires advanced retrieval frameworks capable of navigating complex parameter spaces. We present NEXOTRANS , an atmospheric retrieval framework that integrates Bayesian inference using UltraNest / PyMultiNest with four machine learning algorithms: Random Forest , Gradient Boosting , K-Nearest Neighbor , and Stacking Regressor . This hybrid approach enables a comparison between traditional Bayesian methods and computationally efficient machine learning techniques. Additionally, NEXOTRANS incorporates NEXOCHEM , a module for solving equilibrium chemistry. We applied NEXOTRANS to JWST observations of the Saturn-mass exoplanet WASP-39 b, spanning wavelengths from 0.6 to 12.0 μ m using NIRISS, NIRSpec PRISM, and MIRI. Four chemistry models—free, equilibrium, modified hybrid equilibrium, and modified equilibrium-offset chemistry—were explored to retrieve precise volume mixing ratios (VMRs) for H 2 O, CO 2 , CO, H 2 S, and SO 2 . Absorption features in both NIRSpec PRISM and MIRI data constrained SO 2 log VMRs to values between −6.25 and −5.73 for all models except equilibrium chemistry. High-altitude aerosols, including ZnS and MgSiO 3 , were inferred, with constraints on their VMRs, particle sizes, and terminator coverage fractions, providing insights into cloud composition. For the best-fit modified hybrid equilibrium model, we derived supersolar elemental abundances of \,\rm{O/H}\,=14.{12}_{-1.82}^{+2.86}\times solar, \,\rm{C/H}\,=21.{37}_{-3.18}^{+4.93}\times solar, and \,\rm{S/H}\,=5.{37}_{-0.65}^{+0.79}\times solar, along with a C/O ratio of {1.35}_{-0.02}^{+0.05}\times solar. These results demonstrate NEXOTRANS ’s potential to enhance JWST data interpretation, advancing comparative exoplanetology efficiently.}, archive = {J_ApJ}, author = {Tonmoy Deka and Tasneem Basra Khan and Swastik Dewan and Priyankush Ghosh and Debayan Das and Liton Majumdar}, doi = {10.3847/1538-4357/add33d}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {50}, shortjournal = {The Astrophys. J.}, title = {A next-generation exoplanet atmospheric retrieval framework for transmission spectroscopy (NEXOTRANS): Comparative characterization for WASP-39 b using JWST NIRISS, NIRSpec PRISM, and MIRI observations}, volume = {989}, year = {2025}, }
• (2025). Extended emission-line region in a poststarburst galaxy hosting tidal disruption event AT2019qiz and quasiperiodic eruptions. ApJ, 989(1), 49. (www)

  @article{ , abstract = {We present a comprehensive analysis of the extended emission-line region (EELR) in the host galaxy of the tidal disruption event (TDE) AT2019qiz, utilizing Very Large Telescope (VLT)/MUSE integral-field spectroscopy. The high spatial-resolution data reveal a biconical emission structure approximately 3.7 kpc in scale within the galactic center, characterized by a prominent [O iii ] line in the nucleus and significant [N ii ] line emission extending into the EELR. Spectral analysis of the EELR indicates line ratios consistent with Seyfert ionization in the center and LINER-type ionization in the outer diffuse region, suggesting ionization from galactic nuclear activity. The required ionizing luminosity, estimated from the H α and H β luminosities based on the photoionization and recombination balance assumption, is 10 41.8 erg s −1 for all spaxels classified as active galactic nucleus (AGN), and 10 40.7 erg s −1 for spaxels in the central 0.9 kpc Seyfert region. However, the current bolometric luminosity of the nucleus L bol ≤ 10 40.8 erg s −1 , estimated from quiescent-state soft X-ray observations, is insufficient to ionize the entire EELR, implying a recently faded AGN or a delayed response to historical activity. Stellar population analysis reveals a poststarburst characteristic in the EELR, and the gas kinematics show disturbances and noncircular components compared to the stellar kinematics. Notably, the recent detection of quasiperiodic eruptions (QPEs) in the X-ray light curve of AT2019qiz confirms the TDE–QPE association. Our findings provide direct evidence for an AGN-like EELR in the host galaxy of the nearest TDE with QPE detection, offering new insights into the complex interplay between TDEs, QPEs, AGN activity, and host-galaxy evolution.}, archive = {J_ApJ}, author = {Yifei Xiong and Ning Jiang and Zhen Pan and Lei Hao and Zhenzhen Li}, doi = {10.3847/1538-4357/ade2d7}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {49}, shortjournal = {The Astrophys. J.}, title = {Extended emission-line region in a poststarburst galaxy hosting tidal disruption event AT2019qiz and quasiperiodic eruptions}, volume = {989}, year = {2025}, }
• (2025). Estimating fe and mg abundances in the milky way dwarf galaxies using Subaru/HSC and DEIMOS. ApJ, 989(1), 48. (www)

  @article{ , abstract = {We investigate the chemical abundance distributions of the Fornax, Sculptor, Ursa Minor, and Draco dwarf galaxies using Subaru/Hyper Suprime-Cam (HSC) photometric data. The HSC data set, which includes broadband g and i filters and the narrowband NB515 filter, offers sensitivity to iron and magnesium abundances, as well as surface gravity, enabling the identification of giant stars and foreground dwarfs. For analysis, we selected a total of 6713 giant candidates using a random forest regressor trained on medium-resolution ( R ∼ 6000) Keck/Deep Imaging Multi-Object Spectrograph spectroscopic data. Our analysis reveals the extent of radial metallicity gradients in the galaxies. Such trends, not detectable in earlier studies, are now captured owing to the substantially enlarged sample size and areal coverage provided by the HSC data. These results are also consistent with chemical abundance patterns previously observed in the central regions through spectroscopic studies. Furthermore, we infer that Fornax underwent extended star formation, whereas Sculptor formed both metal-poor and metal-rich stars over a shorter time. Ursa Minor and Draco appear to have experienced brief, intense star formation episodes leading to nearly extinguished star formation. This study underscores the critical role of the expanded HSC data set in revealing chemical gradients that were previously inaccessible. Future work incorporating additional spectra of metal-poor stars and age-sensitive isochrone modeling will enable more accurate maps of chemical abundance distributions.}, archive = {J_ApJ}, author = {Jihye Hong and Evan N. Kirby and Tiffany M. Tang and Masashi Chiba and Yutaka Komiyama and Lauren E. Henderson and Itsuki Ogami and Timothy C. Beers}, doi = {10.3847/1538-4357/ade679}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {48}, shortjournal = {The Astrophys. J.}, title = {Estimating fe and mg abundances in the milky way dwarf galaxies using Subaru/HSC and DEIMOS}, volume = {989}, year = {2025}, }
• (2025). Cosmology with topological deep learning. ApJ, 989(1), 47. (www)

  @article{ , abstract = {The standard cosmological model with cold dark matter posits a hierarchical formation of structures. We introduce topological neural networks (TNNs), implemented as message-passing neural networks on higher-order structures, to effectively capture the topological information inherent in these hierarchies that traditional graph neural networks (GNNs) fail to account for. Our approach not only considers the vertices and edges that comprise a graph but also extends to higher-order cells such as tetrahedra, clusters, and hyperedges. This enables message-passing between these heterogeneous structures within a combinatorial complex. Furthermore, our TNNs are designed to conserve the E (3) invariance, which refers to the symmetry arising from invariance against translations, reflections, and rotations. When applied to the Quijote suite, our TNNs achieve a significant reduction in the mean squared error. Compared to our GNNs, which lack higher-order message-passing, ClusterTNNs show improvements of up to 22% in Ω m and 34% in σ 8 jointly, while the best FullTNN achieves an improvement of up to 60% in σ 8 . In the context of the CAMELS suite, our models yield results comparable to the current GNN benchmark, albeit with a slight decrease in performance. We emphasize that our topology and symmetry-aware neural networks provide enhanced expressive power in modeling the large-scale structures of our Universe.}, archive = {J_ApJ}, author = {Jun-Young Lee and Francisco Villaescusa-Navarro}, doi = {10.3847/1538-4357/ade806}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {47}, shortjournal = {The Astrophys. J.}, title = {Cosmology with topological deep learning}, volume = {989}, year = {2025}, }
• (2025). GLIMPSE: An ultrafaint ≃105 m⊙ pop III galaxy candidate and first constraints on the pop III UV luminosity function at z ≃ 6–7. ApJ, 989(1), 46. (www)

  @article{ , abstract = {Detecting the first generation of stars, Population III (Pop III), has been a long-standing goal in astrophysics, yet they remain elusive even in the JWST era. Here we present a novel NIRCam-based selection method for Pop III galaxies, and carefully validate it through completeness and contamination simulations. We systematically search ≃ 500 arcmin 2 across JWST legacy fields for Pop III candidates, including GLIMPSE, which, assisted by gravitational lensing, has produced JWST’s deepest NIRCam imaging thus far. We discover one promising Pop III galaxy candidate (GLIMPSE-16043) at z=6.5{0}_{-0.24}^{+0.03} , a moderately lensed galaxy ( \mu =2.{9}_{-0.2}^{+0.1} ) with an intrinsic UV magnitude of {M}_{{\rm{UV}}}=-15.8{9}_{-0.14}^{+0.12} . It exhibits key Pop III features: strong H α emission (rest-frame EW 2810 ± 550 Å); a Balmer jump; no dust (UV slope β = −2.34 ± 0.36); and undetectable metal lines (e.g., [O iii ]; [O iii ]/H β < 0.44), implying a gas-phase metallicity of Z gas / Z ⊙ < 0.5%. These properties indicate the presence of a nascent, metal-deficient young stellar population (<5 Myr) with a stellar mass of ≃10 5 M ⊙ . Intriguingly, this source deviates significantly from the extrapolated UV–metallicity relation derived from recent JWST observations at z = 4–10, consistent with UV enhancement by a top-heavy Pop III initial mass function or the presence of an extremely metal-poor active galactic nucleus. We also derive the first observational constraints on the Pop III UV luminosity function at z ≃ 6–7. The volume density of GLIMPSE-16043 (≈10 −4 cMpc −3 ) is in excellent agreement with theoretical predictions, independently reinforcing its plausibility. This study demonstrates the power of our novel NIRCam method to finally reveal distant galaxies even more pristine than the Milky Way’s most metal-poor satellites, thereby promising to bring us closer to the first generation of stars than we have ever been before.}, archive = {J_ApJ}, author = {Seiji Fujimoto and Rohan P. Naidu and John Chisholm and Hakim Atek and Ryan Endsley and Vasily Kokorev and Lukas J. Furtak and Richard Pan and Boyuan Liu and Volker Bromm and Alessandra Venditti and Eli Visbal and Richard Sarmento and Andrea Weibel and Pascal A. Oesch and Gabriel Brammer and Daniel Schaerer and Angela Adamo and Danielle A. Berg and Rachel Bezanson and Rychard Bouwens and Iryna Chemerynska and Adélaïde Claeyssens and Miroslava Dessauges-Zavadsky and Anna Frebel and Damien Korber and Ivo Labbe and Rui Marques-Chaves and Jorryt Matthee and Kristen B. W. McQuinn and Julian B. Muñoz and Priyamvada Natarajan and Alberto Saldana-Lopez and Katherine A. Suess and Marta Volonteri and Adi Zitrin}, doi = {10.3847/1538-4357/ade9a1}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {46}, shortjournal = {The Astrophys. J.}, title = {GLIMPSE: An ultrafaint ≃105 m⊙ pop III galaxy candidate and first constraints on the pop III UV luminosity function at z ≃ 6–7}, volume = {989}, year = {2025}, }
• (2025). Analysis of ion cyclotron waves during cassini’s flybys of enceladus. ApJ, 989(1), 45. (www)

  @article{ , abstract = {Ion cyclotron waves (ICWs) are ubiquitous phenomena within Saturn’s magnetosphere, particularly in the vicinity of Enceladus. This study focuses on the Cassini spacecraft’s flyby data of Enceladus to investigate the spatial distribution and properties of ICWs. We categorize ICWs into two distinct types based on their frequency characteristics: Type I, with frequencies deviating from the local ion cyclotron trend, detected during high-inclination flybys; and Type II, with frequencies closely following the local trend, observed during horizontal flybys. Moreover, we identify the simultaneous detection of ICWs and magnetosonic waves within Saturn’s magnetosphere, providing new insights into their generation and propagation mechanisms. Our results show that ICWs serve as crucial diagnostic tools for evaluating local plasma conditions and the dynamics of Saturn’s magnetosphere. Furthermore, this study highlights the broader implications of ICWs for comparative planetary magnetospheric research, providing guidance for investigating similar processes at other planetary systems, such as Jupiter’s moons Io and Europa.}, archive = {J_ApJ}, author = {Shangchun Teng and Jian Zhang and Zhonghua Yao and Peng Xiao}, doi = {10.3847/1538-4357/adea78}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {45}, shortjournal = {The Astrophys. J.}, title = {Analysis of ion cyclotron waves during cassini’s flybys of enceladus}, volume = {989}, year = {2025}, }
• (2025). The radio spectral energy distribution and star formation calibration in MIGHTEE-COSMOS highly star-forming galaxies at 1.5 < z < 3.5. ApJ, 989(1), 44. (www)

  @article{ , abstract = {Studying the radio spectral energy distribution (SED) of distant galaxies is essential for understanding their assembly and evolution over cosmic time. We present rest-frame radio SEDs of a sample of 160 star-forming galaxies at 1.5 < z < 3.5 in the Cosmic Evolution Survey field as part of the MeerKAT International GHz Tiered Extragalactic Exploration project. MeerKAT observations combined with archival Very Large Array and Giant Metrewave Radio Telescope data allow us to determine the integrated mid-radio ( ν = 1–10 GHz) continuum (MRC) luminosity and magnetic field strength. A Bayesian method is used to model the SEDs and to separate the free–free and synchrotron emission. We also calibrate the star formation rate (SFR) in radio both directly through SED analysis and indirectly through the infrared–radio correlation (IRRC). With a mean value of α nt ≃ 0.7, the synchrotron spectral index flattens with both redshift and specific SFR, indicating that cosmic rays are more energetic in the early Universe due to higher star formation activity. The magnetic field strength increases with redshift, B ∝ (1 + z ) (0.7±0.1) , and SFR as B ∝ SFR 0.3 , suggesting a small-scale dynamo acting as its main amplification mechanism. Taking into account the evolution of the SEDs, the IRRC is redshift invariant, and it does not change with stellar mass at 1.5 < z < 3.5, although the correlation deviates from linearity. Similarly, we show that the SFR traced using the integrated MRC luminosity is redshift invariant.}, archive = {J_ApJ}, author = {Fatemeh Tabatabaei and Maryam Khademi and Matt J. Jarvis and Russ Taylor and Imogen H. Whittam and Fangxia An and Reihaneh Javadi and Eric J. Murphy and Mattia Vaccari}, doi = {10.3847/1538-4357/ade233}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {44}, shortjournal = {The Astrophys. J.}, title = {The radio spectral energy distribution and star formation calibration in MIGHTEE-COSMOS highly star-forming galaxies at 1.5 < z < 3.5}, volume = {989}, year = {2025}, }
• (2025). The coevolution of stellar wind-blown bubbles and photoionized gas. II. 3D RMHD simulations and tests of semianalytic models. ApJ, 989(1), 43. (www)

  @article{ , abstract = {In a companion paper (Paper I), we presented a coevolution model (CEM) in which to consider the evolution of feedback bubbles driven by massive stars through both stellar winds and ionizing radiation, outlining when either of these effects is dominant and providing a model for how they evolve together. Here we present results from 3D radiation magnetohydrodynamical simulations of this scenario for parameters typical of massive star-forming clouds in the Milky Way: precisely the regime where we expect both feedback mechanisms to matter. While we find that the CEM agrees with the simulations to within 25% for key parameters and modestly outperforms previous idealized models, disagreements remain. We show that these deviations originate mainly from the CEM’s lack of (i) background inhomogeneity caused by turbulence and (ii) time-variable momentum enhancements in the wind-blown bubble (WBB). Additionally, we find that photoionized gas acts similarly to magnetic fields by decreasing the WBB’s surface area. This causes a decrease in the amount of cooling at the WBB’s interface, resulting in an enhanced WBB dynamical impact.}, archive = {J_ApJ}, author = {Lachlan Lancaster and Chang-Goo Kim and Jeong-Gyu Kim and Eve C. Ostriker and Greg L. Bryan}, doi = {10.3847/1538-4357/ade66c}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {43}, shortjournal = {The Astrophys. J.}, title = {The coevolution of stellar wind-blown bubbles and photoionized gas. II. 3D RMHD simulations and tests of semianalytic models}, volume = {989}, year = {2025}, }
• (2025). The coevolution of stellar wind-blown bubbles and photoionized gas. i. physical principles and a semianalytic model. ApJ, 989(1), 42. (www)

  @article{ , abstract = {We propose a new framework for the simultaneous feedback of stellar winds and photoionizing radiation from massive stars, distinguishing the locations where forces are applied, and consequences for internal spatiotemporal evolution of the whole feedback bubble (FB). We quantify the relative dynamical importance of wind-blown bubbles (WBBs) versus the photoionized region (PIR) by the ratio of the radius at which the WBB is in pressure equilibrium with the PIR, R eq , to the Strömgren radius, R St . ζ ≡ R eq / R St quantifies the dynamical dominance of WBBs ( ζ > 1) or the PIR ( ζ < 1). We calculate ζ and find that, for momentum-driven winds, 0.1 ≲ ζ ≲ 1 for the star-forming regions in (i) typical Milky Way–like giant molecular clouds, (ii) the most massive of individual OB stars, and (iii) dense, low-metallicity environments, relevant in the early Universe. In this regime, both WBBs and the PIR are dynamically important to the expansion of the FB. We develop a semianalytic coevolution model (CEM) that takes into account the spatial distribution of forces and the back reactions of both the WBB and PIR. In the ζ < 1 regime where the CEM is most relevant, the model differs in the total FB momentum by up to 25% compared to naive predictions. In the weak-wind limit of ζ ≪ 1, applicable to individual OB stars or low-mass clusters, the CEM has factors ≳2 differences in WBB properties. In a companion paper, we compare these models to 3D, turbulent hydrodynamical simulations.}, archive = {J_ApJ}, author = {Lachlan Lancaster and Jeong-Gyu Kim and Greg L. Bryan and Shyam H. Menon and Eve C. Ostriker and Chang-Goo Kim}, doi = {10.3847/1538-4357/ade66b}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {42}, shortjournal = {The Astrophys. J.}, title = {The coevolution of stellar wind-blown bubbles and photoionized gas. i. physical principles and a semianalytic model}, volume = {989}, year = {2025}, }
• (2025). Discovery of Jet–Bubble–Disk interaction: Jet feedback on a protoplanetary disk via an expanding bubble in WSB 52. ApJ, 989(1), 41. (www)

  @article{ , abstract = {While stellar jets and outflows are fueled by accretion from disks, their direct influence on disks remain unexplored. Here, we revisit Atacama Large Millimeter/submillimeter Array observations of 12 CO ( J = 2–1) line emission for the young stellar object WSB 52. We identify an expanding bubble that interacts with its protoplanetary disk. Given that the disk axis points toward the bubble’s center and the kinetic energy of the bubble is roughly 10 41 erg, we postulate that stellar jets, aligned with the disk axis, have triggered the bubble. The bubble morphology is consistent with uniform expansion with partial concavity, implying the bubble-disk interaction. Correspondingly, the shape and the velocity field of protoplanetary disk appear to be deformed and exhibit high-velocity components, suggesting strong interactions and mass loss from the disk. The discovery of jet feedback onto the disk via the bubble—which we term the jet-bubble-diskjet–bubble–disk interaction—sheds new light on the dynamical processes governing star and planet formation.}, archive = {J_ApJ}, author = {Masataka Aizawa and Ryuta Orihara and Munetake Momose}, doi = {10.3847/1538-4357/add47e}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {41}, shortjournal = {The Astrophys. J.}, title = {Discovery of Jet–Bubble–Disk interaction: Jet feedback on a protoplanetary disk via an expanding bubble in WSB 52}, volume = {989}, year = {2025}, }
• (2025). Magnetic field in the lobes of the seyfert galaxy NGC 3516: Suggestions of a helical field. ApJ, 989(1), 40. (www)

  @article{ , abstract = {We present polarization images from the Karl G. Jansky Very Large Array and the Giant Metrewave Radio Telescope at 5.5 GHz, 10 GHz, and 663 MHz of the changing-look active galactic nuclei, NGC 3516. A transverse gradient in the rotation measure (RM) is detected in the northern and southern kiloparsec-scale lobes. Such gradients have typically been suggested to be signatures of a helical magnetic ( B -) field. We detect circular polarization in the core and inner jet-knot of this source, which is known to host a precessing radio jet interacting with emission-line gas. Soft X-ray emission from the Chandra X-ray Observatory suggests the presence of a hot wind emerging from the nucleus of NGC 3516. Taken together with the RM gradient, this presents a picture of jet+wind outflow in this Seyfert galaxy with the B -field confining both the jet and lobe emission. A magnetically driven outflow may, in turn, cause accretion disk warping and jet precession, which is observed in the case of NGC 3516.}, archive = {J_ApJ}, author = {Salmoli Ghosh and Preeti Kharb and Esha Sajjanhar and Alice Pasetto and Biny Sebastian}, doi = {10.3847/1538-4357/ade98d}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {40}, shortjournal = {The Astrophys. J.}, title = {Magnetic field in the lobes of the seyfert galaxy NGC 3516: Suggestions of a helical field}, volume = {989}, year = {2025}, }
• (2025). The relation between solar spicules and magnetohydrodynamic shocks. ApJ, 989(1), 39. (www)

  @article{ , abstract = {Spicules are thin, elongated, jet-like features seen in observations of the solar atmosphere, at the interface between the solar photosphere and the corona. These features exhibit highly complex dynamics and are a necessary connecting link between the cooler, denser solar chromosphere and the extremely hot, tenuous corona. In this work, we explore the spatial and temporal relation between solar spicules and magnetohydrodynamic (MHD) shocks using data from a 2D radiative MHD simulation of the solar atmosphere driven by solar convection. Here, we demonstrate, through direct identification, that slow MHD shocks, which propagate along magnetic field lines, are regions of strong positive vertical acceleration of the plasma that forms the tip of the spicule material during its rise phase. We quantify the effect of pressure and Lorentz forces on the acceleration of the plasma inside the shocks during the rise of spicules. The causality between spicule and shock propagation in the atmosphere of the model is also investigated. It is further shown that the strength of these shocks may play a vital role in determining the height of the spicules, supporting the idea that shocks act as drivers of some spicules. In addition, we also find the presence of structures similar to propagating coronal disturbances (PCDs) in the simulation, linked with the spicules. Here, PCDs appear to be associated with the shock waves driving the spicules that subsequently propagate into the corona and have similar speeds to those reported in observations.}, archive = {J_ApJ}, author = {Sankalp Srivastava and Piyali Chatterjee and Sahel Dey and Robertus Erdélyi}, doi = {10.3847/1538-4357/ade9b4}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {39}, shortjournal = {The Astrophys. J.}, title = {The relation between solar spicules and magnetohydrodynamic shocks}, volume = {989}, year = {2025}, }
• (2025). GD-1 and the milky way starless dark matter subhalos. ApJ, 989(1), 38. (www)

  @article{ , abstract = {Measurements of the GD-1 star stream velocity distribution within ±3° of the centerline find a total line-of-sight velocity spread of 5–6 km s −1 in the-well measured ϕ 1 = [−30, 0] region. The velocity spread is far above the ∼2–3 km s −1 of a dissolved globular cluster in a smooth galactic potential. Dynamical heating of the GD-1 star stream is simulated in an evolving model Milky Way potential that includes the subhalos extracted from cosmological cold dark matter (CDM) and warm dark matter (WDM) Milky Way–like halos. The model bridges fully cosmological Milky Way–like halos and late-time static Milky Way potentials, allowing individual streams to be accurately integrated. An evolving CDM subhalo population acting for ∼11 Gyr heats GD-1 to 6.2  ±  1.7 km s −1 . The WDM (7 keV and lighter) models develop a velocity dispersion of 3.9  ±  0.2 km s −1 , only slightly greater than the 3.5 km s −1 in an evolving smooth halo without subhalos for 11 Gyr. The dynamical age of the best model stream is close to the isochrone age of the stars in the stream. Subhalos with masses in the decade around 10 7.5 M ⊙ , below the mass range of dwarf galaxies, dominate the dynamical stream heating.}, archive = {J_ApJ}, author = {Raymond G. Carlberg}, doi = {10.3847/1538-4357/adec91}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {38}, shortjournal = {The Astrophys. J.}, title = {GD-1 and the milky way starless dark matter subhalos}, volume = {989}, year = {2025}, }
• (2025). MeV cosmic-ray electrons modify the TeV pair-beam plasma instability. ApJ, 989(1), 37. (www)

  @article{ , abstract = {Relativistic pair beams created in the intergalactic medium (IGM) by TeV gamma rays from blazars are expected to produce a detectable GeV-scale electromagnetic cascade, but the cascade component is absent in the spectra of many hard-spectrum TeV-emitting blazars. One common explanation is that weak intergalactic magnetic fields deflect the electron–positron pairs away from our line of sight. An alternative possibility is that electrostatic beam-plasma instabilities drain the energy of these pairs before a cascade can develop. Recent studies have shown that beam scattering by oblique electrostatic modes leads to minimal energy loss. But these modes might be suppressed by linear Landau damping (LLD) due to MeV-scale cosmic-ray electrons in the IGM. In this work, we explore the impact of LLD on the energy-loss efficiency of plasma instabilities in pair beams associated with 1ES 0229+200. We find that LLD effectively suppresses oblique electrostatic modes, while quasi-parallel ones grow to larger amplitudes. In this way, LLD enhances the energy-loss efficiency of the instability by more than an order of magnitude.}, archive = {J_ApJ}, author = {Mahmoud Alawashra and Yuanyuan Yang and Christopher M. Hirata and Heyang Long and Martin Pohl}, doi = {10.3847/1538-4357/adec9e}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {37}, shortjournal = {The Astrophys. J.}, title = {MeV cosmic-ray electrons modify the TeV pair-beam plasma instability}, volume = {989}, year = {2025}, }
• (2025). Radio morphology of gamma-ray sources. II. giant radio galaxies. ApJ, 989(1), 36. (www)

  @article{ , abstract = {Giant radio sources, including galaxies and quasars (hereafter GRSs), are active galactic nuclei (AGN) hosting relativistic jets with source sizes exceeding a projected length of 0.7 Mpc. They are crucial to understanding the evolution of radio sources and their interaction with the surrounding environment. Some of these enigmatic objects, e.g., NGC 315, have also been reported as γ -ray emitters. Since GRSs are thought to be aligned close to the plane of the sky, they are invaluable targets to explore the radiative mechanisms responsible for the observed γ -ray emission. We have carried out a systematic search of γ -ray-emitting GRSs using sensitive low-resolution radio surveys, such as by the Low Frequency Array, NRAO Very Large Array Sky Survey, and Rapid ASKAP Continuum Survey, and considering the fourth data release of the fourth Fermi Large Area Telescope γ -ray source (4FGL-DR4) catalog. By carefully inspecting the radio maps of all AGN included in the 4FGL-DR4 catalog, we have identified 16 γ -ray-emitting GRSs, including eight that are being reported as GRSs for the first time. Some of their observed parameters, e.g., core dominance, appeared to differ from those found for the non- γ -ray detected GRS population, possibly due to the relatively small viewing angle of the γ -ray-emitting jet. The observed γ -ray properties of these objects were found to be similar to those of non-GRS γ -ray-emitting misaligned AGN. We conclude that the origin of the γ -ray emission could be similar in both source populations.}, archive = {J_ApJ}, author = {Vaidehi S. Paliya and D. J. Saikia and G. Bruni and Alberto Domínguez and C. S. Stalin}, doi = {10.3847/1538-4357/adef0c}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {36}, shortjournal = {The Astrophys. J.}, title = {Radio morphology of gamma-ray sources. II. giant radio galaxies}, volume = {989}, year = {2025}, }
• (2025). Self-consistent dynamical and chaotic tides in the REBOUNDx framework. ApJ, 989(1), 35. (www)

  @article{ , abstract = {At high eccentricities, tidal forcing excites vibrational modes within orbiting bodies known as dynamical tides. In this paper, we implement the coupled evolution of these modes with the body’s orbit in the REBOUNDx framework, an extension to the popular N -body integrator REBOUND . We provide a variety of test cases relevant to exoplanet dynamics and demonstrate overall agreement with prior studies of dynamical tides in the secular regime. Our implementation is readily applied to various high-eccentricity scenarios and allows for fast and accurate N -body investigations of astrophysical systems for which dynamical tides are relevant.}, archive = {J_ApJ}, author = {Donald Liveoak and Sarah C. Millholland and Michelle Vick and Daniel Tamayo}, doi = {10.3847/1538-4357/adefe7}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {35}, shortjournal = {The Astrophys. J.}, title = {Self-consistent dynamical and chaotic tides in the REBOUNDx framework}, volume = {989}, year = {2025}, }
• (2025). Biosignature false positives in potentially habitable planets around m dwarfs: The effect of UV radiation from one flare. ApJ, 989(1), 34. (www)

  @article{ , abstract = {Many past studies have predicted the steady-state production and maintenance of abiotic O 2 and O 3 in the atmospheres of CO 2 -rich terrestrial planets orbiting M dwarf stars. However, the time-dependent responses of these planetary atmospheres to flare events—and the possible temporary production or enhancement of false-positive biosignatures therein—has been comparatively less well studied. Most past works that have modeled the photochemical response to flares have assumed abundant free oxygen, like that of the modern or Proterozoic Earth. Here we examine in detail the photochemical impact of the UV emitted by a single flare on abiotic O 2 /O 3 production in prebiotic, CO 2 -dominated atmospheres of M dwarf planets with CO 2 levels ranging from 3% to 80% of 1 bar. We find that a single flare generally destroys O 2 and O 3 over short timescales while modestly enhancing their column densities over intermediate timescales. We simulate the spectral observables of both the steady-state atmosphere and time-dependent spectral response over the flare window for both emitted and transmitted light spectra. Over the course of the flare, the O 3 UV Hartley band is decreased by a maximum of 47 ppm. In both emitted and transmitted light spectra, the 9.65 μ m O 3 band is hidden by the overlapping 9.4 μ m CO 2 band for all scenarios considered. Overall, we find that the possible enhancements of abiotic O 3 due to a single flare are small compared to O 3 ’s sensitivity to other parameters such as CO 2 and H 2 O abundances or the availability of reducing gases such as H 2 .}, archive = {J_ApJ}, author = {Arturo Miranda-Rosete and Antígona Segura and Edward W. Schwieterman}, doi = {10.3847/1538-4357/acebec}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {34}, shortjournal = {The Astrophys. J.}, title = {Biosignature false positives in potentially habitable planets around m dwarfs: The effect of UV radiation from one flare}, volume = {989}, year = {2025}, }
• (2025). Analysis of two models for the angular structure of the outflows producing the Swift/XRT “Larger-angle emission” of gamma-ray bursts. ApJ, 989(1), 33. (www)

  @article{ , abstract = {The quasi-instantaneous emission from a relativistic surface endowed with a Lorentz factor that decreases away from the outflow symmetry axis can naturally explain the three phases observed by Swift X-Ray Telescope (XRT) in gamma-ray bursts (GRBs) and their afterglows (GRB tail, afterglow plateau, and postplateau) based only on the angular change of the relativistic Doppler boost across the outflow surface. We develop further the analytical formalism of the “larger-angle emission” model for the case of “ n -exponential” outflows (where the Lorentz factor Γ dependence of the angular location θ is {\rm{\Gamma }}\sim \exp \{-{(\theta /{\theta }_{c})}^{n}\} ), and compare its ability to account for the X-ray emission of XRT afterglows relative to that of “power-law” outflows (Γ ∼ θ − g ). Power-law outflows yield longer afterglow plateaus, followed by slower postplateau flux decays than n -exponential outflows, features which may be used in identifying which type of angular structure is at work in a given afterglow. Identifying the Γ( θ ) angular structure that accommodates XRT light curves is slightly complicated by the fact that the afterglow X-ray light curve is also determined by how two characteristics of the comoving-frame emission spectrum (peak energy {E}_{p}^{{\prime} } and peak intensity {i}_{p}^{{\prime} } ) change with the angular location or, equivalently, with the Lorentz factor. Here, we assume power-law Γ dependences of those spectral characteristics and find that, unlike power-law outflows, n -exponential outflows cannot account for plateaus with a temporal dynamical range larger than 100 (2 dex in logarithmic space). To capture all the information contained in XRT afterglow measurements (0.3–10 keV unabsorbed flux and effective spectral slope), we calculate 0.3 and 10 keV light curves using a broken-power-law emission spectrum of peak energy and low- and high-energy slopes that are derived from the effective slope measured by XRT. This economical peak energy determination is found to be consistent with the results of more expensive spectral fits. The angular distributions of the Lorentz factor, comoving frame peak energy, and peak intensity ( {\rm{\Gamma }}(\theta ),{E}_{p}^{{\prime} }(\theta ),{i}_{p}^{{\prime} }(\theta ) ) constrain the (yet-to-be determined) convolution of various features of the production of relativistic jets by solar-mass black holes and of their propagation through the progenitor/circumburst medium, while the {E}_{p}^{{\prime} }({\rm{\Gamma }}) and {i}_{p}^{{\prime} }({\rm{\Gamma }}) dependences may constrain the GRB dissipation mechanism and the GRB emission process.}, archive = {J_ApJ}, author = {A. Panaitescu}, doi = {10.3847/1538-4357/add721}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {33}, shortjournal = {The Astrophys. J.}, title = {Analysis of two models for the angular structure of the outflows producing the Swift/XRT “Larger-angle emission” of gamma-ray bursts}, volume = {989}, year = {2025}, }
• (2025). Formation pathways of compact elliptical galaxies: Perspective of internal structures. ApJ, 989(1), 32. (www)

  @article{ , abstract = {We present a structural analysis of 138 compact elliptical galaxies (cEs) in the redshift range of z < 0.05 using the Sloan Digital Sky Survey (SDSS) DR12 data. We perform single- and double-component Sérsic model fitting to their SDSS r -band surface brightness profiles. By dividing cEs into those with [cE(w)] and without [cE(w/o)] a bright host galaxy, we find a significant structural dichotomy: the majority (∼85%) of cE(w)s exhibit single-component profiles, while a similar proportion (∼85%) of isolated cE(w/o)s display double-component profiles, characterized by a compact, inner component and a diffuse, disk-like outer component. These results suggest that host-associated cE(w)s primarily form through the tidal stripping of larger progenitors, resulting in a compact bulge-like core. In contrast, isolated cE(w/o)s appear to form intrinsically at early epochs, likely through gas-rich mergers, and retain disk-like outer structures. The Sérsic index distribution of cE(w)s with single-component structure indicates progenitor types ranging from pseudobulge to classical bulge, supported by differences in stellar populations. A small fraction of cEs, including double-component cE(w)s and single-component cE(w/o)s, suggests complex evolutionary channels involving environmental capture or ejection. Our results emphasize that the structural characteristics of cEs, specifically the presence or absence of an extended outer envelope, serve as a crucial diagnostic tool to distinguish tidally stripped remnants from intrinsically formed low-mass cEs in isolation.}, archive = {J_ApJ}, author = {Jinwon Yi and Soo-Chang Rey and Suk Kim and Youngdae Lee}, doi = {10.3847/1538-4357/ade4c3}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {32}, shortjournal = {The Astrophys. J.}, title = {Formation pathways of compact elliptical galaxies: Perspective of internal structures}, volume = {989}, year = {2025}, }
• (2025). Spectroscopic ultraluminous lyα luminosity functions at z = 5.7 and z = 6.6 from HEROES: Evidence for ionized bubbles. ApJ, 989(1), 31. (www)

  @article{ , abstract = {We present spectroscopic Ly α luminosity functions (LFs) at z = 5.7 and z = 6.6 based on a large 209 source sample of Ly α emitter (LAE) candidates identified in Subaru/Hyper Suprime-Cam narrowband imaging and confirmed with Keck II/DEIMOS spectroscopy over a multiyear observing campaign. After applying photometric and spectroscopic cuts to produce homogeneous samples, we use the resulting samples of 49 z = 5.7 and 56 z = 6.6 LAEs to compute spectroscopic LAE LFs at each redshift. We correct our LFs for incompleteness using a source-injection simulation. We find excellent agreement with current spectroscopic and photometric LAE LFs from the literature. We look for evolution over the redshift range z = 5.7–6.6. We find a strong convergence of the LFs at L Lyα ≳ 10 43.4 erg s −1 . This convergence (noted in previous literature) provides strong evidence that the most luminous LAEs at z = 6.6 form ionized bubbles around themselves, allowing for greater Ly α transmission through the neutral intergalactic medium, which is measured as an increase in the bright end of the z = 6.6 LF over the expected evolution in the LF based on the faint end. We infer that ultraluminous LAEs may play a significant role in reionization.}, archive = {J_ApJ}, author = {A. J. Taylor and A. J. Barger and L. L. Cowie and E. M. Hu and A. Songaila}, doi = {10.3847/1538-4357/ade4c7}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {31}, shortjournal = {The Astrophys. J.}, title = {Spectroscopic ultraluminous lyα luminosity functions at z = 5.7 and z = 6.6 from HEROES: Evidence for ionized bubbles}, volume = {989}, year = {2025}, }
• (2025). SO emission in the dynamically perturbed protoplanetary disks around CQ tau and MWC 758. ApJ, 989(1), 30. (www)

  @article{ , abstract = {We report the serendipitous detection of the SO J N = 6 5 –5 4 (219.949 GHz) rotational transition in archival Atacama Large Millimeter/submillimeter Array observations of the spiral hosting protoplanetary disks around CQ Tau (with ≈4.9 σ significance) and MWC 758 (with ≈3.4 σ significance). In the former, the SO emission comes in the shape of a ring, arises from the edge of the continuum cavity, and is qualitatively consistent, at the currently available spectral resolution, with being in Keplerian rotation. In the latter, instead, while arising primarily from inside the continuum cavity, the SO emission also extends to the continuum ring(s), and its morphology and kinematics are less clear. We put these sources in the context of the other protoplanetary disks where SO detections have been previously reported in the literature and discuss the possible origins of SO in terms of (thermal) desorption or formation in the gas-phase. We argue that these processes might be fostered by dynamical perturbations caused by unseen embedded massive companions, shadows, or late-time infall, thus suggesting a possible link between perturbed dynamics and SO emission in (these) protoplanetary disks. If confirmed, our interpretation would imply that chemical evolution timescales could be significantly shorter in these systems than is commonly assumed, indicating that dynamical perturbations might influence the composition of newborn (proto)planets by altering the volatile makeup of their formation environment.}, archive = {J_ApJ}, author = {Francesco Zagaria and Haochang Jiang and Gianni Cataldi and Stefano Facchini and Myriam Benisty and Yuri Aikawa and Sean Andrews and Jaehan Bae and Marcelo Barraza-Alfaro and Pietro Curone and Ian Czekala and Daniele Fasano and Cassandra Hall and Iain Hammond and Jane Huang and John D. Ilee and Andrés F. Izquierdo and Jensen Lawrence and Giuseppe Lodato and François Ménard and Christophe Pinte and Giovanni P. Rosotti and Jochen Stadler and Richard Teague and Leonardo Testi and David Wilner and Andrew Winter and Tomohiro Yoshida}, doi = {10.3847/1538-4357/ade683}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {30}, shortjournal = {The Astrophys. J.}, title = {SO emission in the dynamically perturbed protoplanetary disks around CQ tau and MWC 758}, volume = {989}, year = {2025}, }
• (2025). Peering into the heart of darkness with VLBA: Radio-quiet active galactic nucleus in the JWST north ecliptic pole time-domain field. ApJ, 989(1), 29. (www)

  @article{ , abstract = {We present initial results from the 4.8 GHz Very Long Baseline Array (VLBA) survey of the JWST North Ecliptic Pole Time-Domain Field (TDF). From 106 radio sources found in the Karl G. Jansky Very Large Array (VLA) observations in the TDF, we detected 12 sources (∼11% detection rate) at ∼3.3 μ Jy rms sensitivity and ∼4 mas resolution. Most detections exhibit parsec-scale emission (less than 40 pc) with high VLBA/VLA flux density ratios and brightness temperatures exceeding 10 5 K, confirming nonthermal active galactic nucleus (AGN) activity. Spectral indices α ≳ −0.5 correlate with higher VLBA/VLA flux ratios, consistent with synchrotron emission from AGN coronae or jets. In the majority of our sources, star formation contributes less than 50% of the total VLBA radio emission, with a few cases where the emission is almost entirely AGN driven. Although the radio emission from radio quiet AGN is thought to be primarily driven by star formation, our VLBA observations confirm that there is also often a contribution at various levels from black hole driven AGN. Eight VLBA detections have JWST/NIRCam counterparts, predominantly early-type, bulge-dominated galaxies, which we use to get an estimate of the redshift and star formation rate (SFR). Wide-field Infrared Survey Explorer colors indicate that VLBA detections are either AGN or intermediate-disk-dominated systems, while VLBA nondetections correspond to extended, star-forming galaxies. We compare SFRs derived from previous SCUBA-2 850 μ m observations with new JWST-based estimates, and discuss the observed discrepancies, highlighting JWST’s improved capability to disentangle AGN activity from star formation.}, archive = {J_ApJ}, author = {Payaswini Saikia and Ramon Wrzosek and Joseph Gelfand and Walter Brisken and William Cotton and S. P. Willner and Hansung B. Gim and Rogier A. Windhorst and Vicente Estrada-Carpenter and Ivan Yu. Katkov and Ingyin Zaw and Michael J. Nicandro Rosenthal and Hanaan Shafi and Kenneth Kellermann and James Condon and Anton M. Koekemoer and Christopher J. Conselice and Rafael Ortiz and Christopher N. A. Willmer and Brenda Frye and Norman A. Grogin and Heidi B. Hammel and Seth H. Cohen and Rolf A. Jansen and Jake Summers and Jordan C. J. D’Silva and Simon P. Driver and Nor Pirzkal and Haojing Yan and Min S. Yun}, doi = {10.3847/1538-4357/ade709}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {29}, shortjournal = {The Astrophys. J.}, title = {Peering into the heart of darkness with VLBA: Radio-quiet active galactic nucleus in the JWST north ecliptic pole time-domain field}, volume = {989}, year = {2025}, }
• (2025). Reassessing sub-neptune structure, radii, and thermal evolution. ApJ, 989(1), 28. (www)

  @article{ , abstract = {We present a novel python-based 1D sub-Neptune evolution model that emphasizes the thermal evolution and potential solidification of the rock/iron core and the structure of the radiative atmosphere. This model explores planetary structure from the molten center to nbar pressure levels. Treating the radiative atmosphere is crucial for sub-Neptunes, due to the large scale height and low gravity, which contributes up to 40% of their observed radius, especially for low-mass, highly irradiated planets. Consequently, we generically find that lower H/He mass fractions are needed to match a given planetary radius, compared to previous work. While the presence of metal enrichment in the H/He layers (here modeled as 50× solar) does not substantially influence the size of the convective envelope, it notably reduces the transit radius by shrinking the radiative atmospheric scale height. Sub-Neptunes cool differently from terrestrial planets, with the rock/iron core’s cooling rate limited by the envelope, leading to longer solidification timescales. Complete solidification of the silicate mantle by 10 Gyr is found only for planets with very low masses (≤1 M ⊕ ) and small H/He envelopes (≤0.1%). Dynamo action in sub-Neptune iron cores persists as long as the mantle surface remains molten, often exceeding 10 Gyr, and becomes sensitive to core thermal conductivity after solidification. We examine aspects of “boil-off,” which sets the maximum allowed H/He mass and planetary radius for subsequent evolution. The rock/iron’s cooling energy moderately decreases the post-boil-off H/He mass fraction in planets with large atmospheric scale heights only.}, archive = {J_ApJ}, author = {Yao Tang and Jonathan J. Fortney and Francis Nimmo and Daniel Thorngren and Kazumasa Ohno and Ruth Murray-Clay}, doi = {10.3847/1538-4357/ade7ff}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {28}, shortjournal = {The Astrophys. J.}, title = {Reassessing sub-neptune structure, radii, and thermal evolution}, volume = {989}, year = {2025}, }
• (2025). Time-dependent radiation transport simulations of infrared echoes from dust-shrouded luminous transients. ApJ, 989(1), 27. (www)

  @article{ , abstract = {A range of stellar explosions, including supernovae (SNe), tidal disruption events (TDE), and fast blue optical transients (FBOTs), can occur in dusty environments initially opaque to transients’ optical/UV light, becoming visible only once the dust is destroyed by transients’ rising luminosity. We present axisymmetric, time-dependent radiation transport simulations of dust-shrouded transients with Athena++ and tabulated gray opacities, predicting the light curves of the dust-reprocessed infrared (IR) radiation. The luminosity and timescale of the IR light curve depend on whether the transient rises rapidly or slowly compared to the light-crossing time of the photosphere, t lc . For slow-rising transients ( t rise ≫ t lc ) like SNe, the reprocessed IR radiation diffuses outward through the dust shell faster than the shell sublimates; the IR light curve therefore begins rising prior to the escape of UV/optical light, but peaks on a timescale ∼ t rise shorter than the transient duration. By contrast, for fast-rising transients ( t rise ≪ t lc ) such as FBOTs and some TDEs, the finite light-travel time results in the reprocessed radiation arriving as an “echo” lasting much longer than the transient itself. We explore the effects of the system geometry by considering a torus-shaped distribution of dust. The IR light curves seen by observers in the equatorial plane of the torus resemble those for a spherical dust shell, while polar observers see faster-rising, brighter, and shorter-lived emission. We successfully model the IR excess seen in AT2018cow as a dust echo, supporting the presence of an opaque dusty medium surrounding FBOTs prior to explosion.}, archive = {J_ApJ}, author = {Semih Tuna and Brian D. Metzger and Yan-Fei Jiang and Christopher White}, doi = {10.3847/1538-4357/ade8ed}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {27}, shortjournal = {The Astrophys. J.}, title = {Time-dependent radiation transport simulations of infrared echoes from dust-shrouded luminous transients}, volume = {989}, year = {2025}, }
• (2025). Characterizing the observational properties of the sun’s high-latitude m = 1 inertial mode. ApJ, 989(1), 26. (www)

  @article{ , abstract = {Low- m inertial modes have been recently discovered in the Sun’s high-latitude regions. In this study, we characterize the observational properties of the m = 1 mode by analyzing time–distance subsurface flow maps. Synoptic flow maps, constructed from daily subsurface flow maps using a tracking rate corresponding to the rotation at latitude 65°, are filtered in both the spherical harmonic and Fourier domains to retain only the m = 1 mode and its dominant frequencies. Our analysis reveals a power distribution that is significantly stronger in the northern polar region. The mode’s power exhibits an anticorrelation with solar activity, remaining strong and persistent during the solar activity minimum and becoming weaker and more fragmented during the solar maximum. Magnetic flux transported from low to high latitudes influences both the mode’s power and lifetime, enhancing its power and shortening its lifetime upon arrival. The phases of the m = 1 mode in the northern and southern polar regions are near-antisymmetric for most of the time with short deviations. We also compute zonal and meridional phase velocities of the mode and find that it exhibits significantly less differential rotation than its surrounding plasma. The meridional phase velocity, comprising both the local plasma’s meridional flow and the mode’s intrinsic phase motion, is directed poleward below latitude 70° and equatorward above this latitude. These observational findings underscore the need for a deeper understanding of the internal dynamics of the low- m modes, which may offer valuable insights into the structure and dynamics of the solar interior.}, archive = {J_ApJ}, author = {Boyang Ding and Junwei Zhao and Ruizhu Chen and Matthias Waidele and Sushant S. Mahajan and Oana Vesa}, doi = {10.3847/1538-4357/ade980}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {26}, shortjournal = {The Astrophys. J.}, title = {Characterizing the observational properties of the sun’s high-latitude m = 1 inertial mode}, volume = {989}, year = {2025}, }
• (2025). Cloud-to-cloud velocity dispersions across a local arm segment. ApJ, 989(1), 25. (www)

  @article{ , abstract = {Using a large sample of 9617 molecular clouds (MCs) from the Milky Way Imaging Scroll Painting survey, we mainly measure one-dimensional cloud-to-cloud velocity dispersions across a 450 deg 2 segment of the Local Arm in the Galactic second quadrant. We define the cloud-to-cloud velocity dispersion using two metrics: the standard deviation ( σ bin ) and flux-weighted rms value ( σ bin,w ) of the centroid velocities of 12 CO-detected MCs within spatial bins. The typical values of σ bin and σ bin,w are 7.5 ± 0.5 km s −1 and 6.2 ± 0.5 km s −1 , respectively. After categorizing clouds by sizes into three types: Type S (0.15–1.2 pc), Type M (1.2–4.8 pc), and Type L (≳4.8 pc), we find that the spatial distribution of Type S and M MCs projected onto the Galactic longitude–latitude ( l – b ) plane is generally uniform. Additionally, the cloud-to-cloud velocity dispersion among Type S clouds (∼7.6 and 7.4 km s −1 for σ bin and σ bin,w , respectively) is systematically greater than that among Type M clouds (∼6.7 and 6.0 km s −1 for σ bin and σ bin,w , respectively), with differences of 0.9–1.4 km s −1 . From these measurements, we estimate merger timescales between MCs to be approximately 0.3–0.9 Myr, which is shorter than their internal crossing timescales (∼1 Myr for Type S , ∼2 Myr for Type M , and ≳5 Myr for Type L ). This disparity, particularly pronounced for larger Type L clouds, suggests that MCs are dynamically transient structures, with their gas content changing due to frequent interactions with neighboring clouds.}, archive = {J_ApJ}, author = {Lixia Yuan and Ji Yang}, doi = {10.3847/1538-4357/ade98f}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {25}, shortjournal = {The Astrophys. J.}, title = {Cloud-to-cloud velocity dispersions across a local arm segment}, volume = {989}, year = {2025}, }
• (2025). A large catalog of DA white dwarf characteristics using SDSS and gaia observations. ApJ, 989(1), 24. (www)

  @article{ , abstract = {We present a catalog of 8545 and 19,257 unique DA white dwarfs (WDs) observed in Sloan Digital Sky Survey (SDSS) Data Release 19 and previous SDSS data releases, respectively. This is the largest catalog of both spectroscopic and photometric measurements of DA WDs available to date, and we make this catalog and all codes used to create it publicly available. We measure the apparent radial velocity, spectroscopic effective temperature and surface gravity, and photometric effective temperature and radius for all objects in our catalog. We validate our measurements against other published WD catalogs. For apparent radial velocities, surface gravities, and effective temperatures measured from spectra with signal-to-noise ratios >​ ​​​​​​50, our measurements agree with published SDSS WD catalogs to within 7.5 km s −1 , 0.060 dex, and 2.4%, respectively. For radii and effective temperatures measured with Gaia photometry, our measurements agree with other published Gaia data sets to within 0.0005 R ⊙ and 3%, respectively. We use this catalog to investigate systematic discrepancies between WDs observed in SDSS-V and previous generations of SDSS. For objects observed in both SDSS-V and previous generations, we uncover systematic differences between measured spectroscopic parameters depending on which set of survey data is used. On average, the measured apparent radial velocity of a DA WD is 11.5 km s −1 larger, and the surface gravity is 0.015 dex smaller when a WD’s spectroscopic parameters are measured using SDSS-V data compared to using data from previous generations of SDSS. These differences may be due to changes in the wavelength solution across survey generations.}, archive = {J_ApJ}, author = {Nicole R. Crumpler and Vedant Chandra and Nadia L. Zakamska and Gautham Adamane Pallathadka and Stefan Arseneau and Nicola Gentile Fusillo and J. J. Hermes and Carles Badenes and Priyanka Chakraborty and Boris T. Gänsicke and Sean Morrison and Hans-Walter Rix and Stephen P. Schmidt and Axel Schwope and Keivan G. Stassun}, doi = {10.3847/1538-4357/ade9a9}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {24}, shortjournal = {The Astrophys. J.}, title = {A large catalog of DA white dwarf characteristics using SDSS and gaia observations}, volume = {989}, year = {2025}, }
• (2025). Spectral evolution of GX 17+2 using AstroSat and NICER observations. ApJ, 989(1), 23. (www)

  @article{ , abstract = {We study the spectral evolution of the Z-track source GX 17+2 using AstroSat and NICER observations taken between 2016 and 2020. The AstroSat observations cover the period when the source is in the normal branch (NB) and the flaring branch (FB), while for the NICER ones the variability can be associated with the FB branch. The source spectra at different regions of the branches are well described by accretion disk emission, blackbody surface emission, and a thermal Comptonization component. In the NB, the total bolometric unabsorbed flux remains constant and the variation is due to changes in the Comptonization, disk fluxes. In particular, the inferred luminosity ( L T ) and accretion rate ( \dot{M} ) remain constant, while there is significant variation in the inner disk radii and fraction of disk photons entering the corona, indicating changes in the geometry of the system. On the other hand, in the FB, there is significant variation in luminosity from ∼4.0 to ∼7.0 × 10 38 erg s −1 . Despite this significant variation in luminosity and in the inner disk radii, the accretion efficiency, defined as \eta ={L}_{{\rm{T}}}/\dot{M}{c}^{2} , remains nearly constant at ∼0.20 throughout the evolution of the source, as expected for a neutron star system.}, archive = {J_ApJ}, author = {Sree Bhattacherjee and Ranjeev Misra and Biplob Sarkar and V. Jithesh and Jayashree Roy and Yashpal Bhulla}, doi = {10.3847/1538-4357/ade9ad}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {23}, shortjournal = {The Astrophys. J.}, title = {Spectral evolution of GX 17+2 using AstroSat and NICER observations}, volume = {989}, year = {2025}, }
• (2025). The evolution of substructure during star cluster assembly. ApJ, 989(1), 22. (www)

  @article{ , abstract = {Star cluster formation and assembly occur inside filamentary and turbulent molecular clouds, which imprint both spatial and kinematic substructure on the young cluster. In this paper, we quantify the amount and evolution of this substructure in simulations of star cluster formation that include radiation magnetohydrodynamical evolution of the gas, coupled with detailed stellar dynamics, binary formation and evolution, and stellar feedback. We find that both spatial and kinematic substructure are present at early times. Both are erased as the cluster assembles through the formation of new stars as well as the merger of subclusters. Spatial substructure is erased over a timescale of approximately 2.5 times the initial freefall time of the cloud. Kinematic substructure persists for longer and is still present to the end of our simulations. We also explored our simulations for evidence of early dynamical mass segregation and concluded that the presence of a population of binary stars can accelerate and enhance the mass segregation process.}, archive = {J_ApJ}, author = {Edwin Laverde-Villarreal and Alison Sills and Claude Cournoyer-Cloutier and Veronica Arias Callejas}, doi = {10.3847/1538-4357/ade9b5}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {22}, shortjournal = {The Astrophys. J.}, title = {The evolution of substructure during star cluster assembly}, volume = {989}, year = {2025}, }
• (2025). The NGC 3109 satellite system: The first systematic resolved search for dwarf galaxies around an SMC-mass host. ApJ, 989(1), 21. (www)

  @article{ , abstract = {We report the results of the deepest search to date for dwarf galaxies around NGC 3109, a barred spiral galaxy with a mass similar to that of the Small Magellanic Cloud (SMC), using a semiautomated search method. Using the Dark Energy Camera, we survey a region covering a projected distance of ∼70 kpc of NGC 3109 ( D = 1.3 Mpc, R vir ∼ 90 kpc, M ∼ 10 8 M * ) as part of the MADCASH and DELVE-DEEP programs. We introduce a newly developed semiresolved search method, used alongside a resolved search, to identify crowded dwarf galaxies around NGC 3109. Using both approaches, we successfully recover the known satellites Antlia and Antlia B. We identified a promising candidate, which was later confirmed to be a background dwarf through deep follow-up observations. Our detection limits are well defined, with the sample ∼80% complete down to M V ∼ −8.0, and include detections of dwarf galaxies as faint as M V ∼ −6.0. This is the first comprehensive study of a satellite system through resolved stars around an SMC mass host. Our results show that NGC 3109 has more bright ( M V ∼ −9.0) satellites than the mean predictions from cold dark matter models, but well within the host-to-host scatter. A larger sample of LMC/SMC-mass hosts is needed to test whether or not the observations are consistent with current model expectations.}, archive = {J_ApJ}, author = {Amandine Doliva-Dolinsky and Burçin Mutlu-Pakdil and Denija Crnojević and Dhayaa Anbajagane and Jeffrey L. Carlin and Jonah Medoff and David J. Sand and Erik Tollerud and Sungsoon Lim and Paul Bennet and Alex Drlica-Wagner and Catherine E. Fielder and Jonathan R. Hargis and Kai Herron and Laura Congreve Hunter and Michael G. Jones and Ananthan Karunakaran and Annika H. G. Peter and Aaron J. Romanowsky and Kristine Spekkens and Jay Strader and Beth Willman and Julio A. Carballo-Bello and William Cerny and Astha Chaturvedi and Nitya Kallivayalil and Clara E. Martínez-Vázquez and Gustavo E. Medina and Noelia E. D. Noël and Andrew B. Pace and Alex H. Riley and Joanna D. Sakowska and Adam Smercina and Kathy Vivas and Monika Adamów and Clecio R. Bom and Yumi Choi and Peter S. Ferguson and Mahdieh Navabi and Alfredo Zenteno and (DELVE Collaboration)}, doi = {10.3847/1538-4357/ade9b8}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {21}, shortjournal = {The Astrophys. J.}, title = {The NGC 3109 satellite system: The first systematic resolved search for dwarf galaxies around an SMC-mass host}, volume = {989}, year = {2025}, }
• (2025). Role of nonthermal processes in the quiescent and active millimeter spectrum of a young m dwarf. ApJ, 989(1), 20. (www)

  @article{ , abstract = {Millimeter (mm) emission from F-M dwarfs (cool stars) primarily traces chromospheric activity, with thermal emission thought to dominate in quiescence. Despite the high chromospheric activity, the quiescent mm spectral fluence (mm- S ( ν )) of young (<1 Gyr) M dwarfs (dMs) remains largely unexplored. We present the quiescent mm- S ( ν ) of a young dM, AD Leo, observed around 94 GHz using the Northern Extended Millimetre Array. The observed quiescent mm- S ( ν ) exceeds the thermal flux density from a 1D chromospheric model, constrained by optical-UV spectroscopic data, by up to a factor of 7. This indicates a quasi-steady nonthermal emission powered by suprathermal electrons, unlike in old (>1 Gyr) cool stars, whose quiescent mm- S ( ν ) generally agree with 1D thermal models. The mm-brightness temperature spectral index ( α mm ; T B ( ν ) \,\sim \,{\nu }^{-{\alpha }_{{\rm{mm}}}} ) of AD Leo deviates by a factor of 3 from the α mm – T eff scaling law for old Sun-like stars (A. Mohan et al. 2022 ), while UV Ceti, an older M6V star, follows the trend. Also, we report a double-hump flare with second-scale variability in flux density and spectral index, and a frequency-rising nature with brightness increasing with frequency. The flare resembles certain solar events, but is unlike the second-scale events reported in dMs. The nonthermal flare humps suggest multiple injections of accelerated electrons. The mean flare luminosity (∼2–5 × 10 15 erg s −1 Hz −1 ) and duration (18 ± 2 s) are comparable to flares reported in AU Mic and Proxima Cen, but 100–1000 times weaker than the minutes-long dM flares observed by the South Pole Telescope.}, archive = {J_ApJ}, author = {Atul Mohan and Peter H. Hauschildt and Birgit Fuhrmeister and Surajit Mondal and Vladimir Airapetian and Sven Wedemeyer}, doi = {10.3847/1538-4357/ade9bf}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {20}, shortjournal = {The Astrophys. J.}, title = {Role of nonthermal processes in the quiescent and active millimeter spectrum of a young m dwarf}, volume = {989}, year = {2025}, }
• (2025). Multiwavelength analysis of GRB 250101A: From gamma-ray prompt emission to optical afterglow. ApJ, 989(1), 19. (www)

  @article{ , abstract = {The interaction between the relativistic jet and the circumburst medium produces a multiwavelength afterglow of a gamma-ray burst (GRBs). In this work, we present multiwavelength properties of GRB 250101A based on the observations of Swift, Fermi, and Mephisto. The spectral analysis of Swift/Swift Burst Alert Telescope (BAT) and Fermi/Gamma-ray Burst Monitor (GBM) reveals a soft prompt spectrum with a low-energy photon index of −1.18 and a peak energy of 33 keV, and the isotropic energy is 1.4 × 10 52 erg. The prompt emission of GRB 250101A aligns with Type II GRBs in the Amati relation. Meanwhile, our analysis indicates that GRB 250101A is an X-ray-rich or X-ray-dominated GRB, with intrinsic properties suggesting that it is relatively softer than most classical GRBs. Optical observation with Mephisto, beginning 197 s post-trigger, shows a single power-law decay in uvgriz bands, with F ν ,obs ∝ t −0.76 ν −1.21 . The observed spectral index significantly exceeds theoretical predictions under standard afterglow models, suggesting a color excess of ∼0.216 mag. However, combining X-ray and optical afterglow, we find that GRB 250101A is more likely a “normal burst” rather than an “optical-dark burst,” and the dust extinction effect plays an important role in the optical blue bands. Furthermore, there is a structural change at T 0 + 2924 s in the optical light curve, indicating a density drop of ∼50% in the interstellar medium at a distance of ∼0.13 pc. Our analysis shows that this GRB clearly shows some unique characteristics in its observed X-ray-rich prompt emission as well as the circumburst environment, implying a special progenitor.}, archive = {J_ApJ}, author = {Guowang Du and Yehao Cheng and Yuan-Pei Yang and Jun Yang and Jinghua Zhang and Dan Zhu and Yu Pan and Yuan Fang and Xingzhu Zou and Brajesh Kumar and Helong Guo and Xufeng Zhu and Yangwei Zhang and Fanchuan Kong and Chenxi Shang and Xinlei Chen and Xiangkun Liu and Xiaowei Liu}, doi = {10.3847/1538-4357/adea3d}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {19}, shortjournal = {The Astrophys. J.}, title = {Multiwavelength analysis of GRB 250101A: From gamma-ray prompt emission to optical afterglow}, volume = {989}, year = {2025}, }
• (2025). Signatures of electromagnetic and sound radiation produced by gravitational waves in core-collapse supernovae. ApJ, 989(1), 18. (www)

  @article{ , abstract = {This paper presents the scenario that gravitational waves, generated in the core collapse of a pre-supernova star, can produce both electromagnetic radiation and sound radiation as gravitational waves propagate outward from the collapsing core. While the energy of this coproduced electromagnetic and sound radiation is orders of magnitude smaller than the initiating gravitational radiation, the power may be sufficient to reignite fusion outside the collapsing core. The nonequilibrium reignition of fusion, in roughly the same time frame as the strongest neutrino emissions, would change the configuration of the pre-supernova star and subsequently the ejecta and the evolution of the stellar expansion of the supernova remnant (SNR). Although the coproduced electromagnetic or sound radiation could not contribute directly to the supernova explosion, the associated nonequilibrium reignition of fusion would alter the state outside the core, leaving an observable signature in the ejecta of the SNR. The aim of this paper is to argue that including this hypothesized coproduced radiation in computational models of core-collapse supernovae would contribute to the evolution of the stellar expansion and consequently should be observable in the SNR, providing a confirmation of the conversion processes for gravitational radiation to electromagnetic and sound radiation.}, archive = {J_ApJ}, author = {Preston Jones and Pragati Pradhan and Douglas Singleton}, doi = {10.3847/1538-4357/adea3e}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {18}, shortjournal = {The Astrophys. J.}, title = {Signatures of electromagnetic and sound radiation produced by gravitational waves in core-collapse supernovae}, volume = {989}, year = {2025}, }
• (2025). Galaxy cluster constraints on extensions of modified gravity. ApJ, 989(1), 17. (www)

  @article{ , abstract = {Modified Newtonian dynamics (MOND) has achieved notable success in explaining galaxy-scale phenomena and has made several unexpected, a priori predictions that align with observations. However, MOND struggles to account for the dynamics of galaxy groups and clusters without invoking additional unseen mass. To address these shortcomings, various extensions to MOND have been proposed. Among these, extended MOND (EMOND) and MOND combined with a form of dark matter (DM), denoted MOND + DM, offer distinct theoretical pathways. However, these models often introduce additional degrees of freedom or mathematical complexities that limit their falsifiability. In this work, we investigate the viability of EMOND and MOND + DM in the context of galaxy clusters using both observational and theoretical constraints. We use Chandra observations of cluster temperature profiles, alongside the assumption of hydrostatic equilibrium (HSE), to evaluate the predictive power of these extensions. Our analysis reveals that HSE imposes stringent constraints on MOND-based theories, highlighting points of failure in both the EMOND and MOND + DM paradigms. We derive new theoretical bounds that MOND + DM models must satisfy to remain consistent with observed mass and temperature distributions and show that these can be tested with X-ray observatories such as XRISM. For EMOND, we demonstrate significant inconsistencies between its predictions and observed cluster profiles, suggesting that EMOND is not a viable solution at the cluster scale. Our findings emphasize the need for further theoretical development within the MOND framework to reconcile its success at galaxy scales with its shortcomings in more massive systems.}, archive = {J_ApJ}, author = {E. C. Diggins and D. R. Wik}, doi = {10.3847/1538-4357/adea3f}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {17}, shortjournal = {The Astrophys. J.}, title = {Galaxy cluster constraints on extensions of modified gravity}, volume = {989}, year = {2025}, }
• (2025). Dynamical signatures of trumpler 19: A statistical and photometric perspective. ApJ, 989(1), 16. (www)

  @article{ , abstract = {We present a statistical approach to investigating the dynamical evolution of the old open cluster Trumpler 19. We identified 810 cluster members using an ensemble-based unsupervised machine learning method applied to Gaia Data Release 3 astrometric data. From the color–magnitude diagram, we identified 18 blue straggler stars (BSSs) in Trumpler 19. The mass function of the cluster shows a flatter slope, indicating strong mass segregation and advanced dynamical evolution. We fitted the radial surface density profile and found that the concentration parameter c > 1, suggesting that the cluster has formed a clear core–halo structure as a result of dynamical evolution. We characterized the mass segregation among the cluster members as well as BSSs using the Minimum Spanning Trees method, indicating a significant central concentration. Additionally, the sedimentation level of the BSSs is measured as {A}_{rh}^{+}=0.28\pm 0.05 , further supporting radial segregation. To probe the BSS formation mechanisms, we estimated their fractional mass excess ( M e ), supporting binary mass transfer and mergers as the dominant channels. This is further supported by the presence of six variable BSSs. The dynamical evolution of the cluster is further assessed through its tidal interaction with the Galaxy. Trumpler 19 appears to be within the tidal regime, where strong Galactic tidal forces have a significant influence on the dynamical evolution. This indicates that the cluster may have undergone significant mass-loss processes, potentially leading to its eventual disruption, which is further supported by the orbit analysis of the cluster. We found that Trumpler 19 may have lost more than 95% of its initial mass due to dynamical evolution.}, archive = {J_ApJ}, author = {A. H. Sheikh and Biman J. Medhi and Ram Sagar}, doi = {10.3847/1538-4357/adeb6e}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {16}, shortjournal = {The Astrophys. J.}, title = {Dynamical signatures of trumpler 19: A statistical and photometric perspective}, volume = {989}, year = {2025}, }
• (2025). Low-frequency, wideband study of an active repeater, FRB 20240114A, with the GMRT. ApJ, 989(1), 15. (www)

  @article{ , abstract = {We report the detection of 167 bursts from an active repeater, FRB 20240114A, using the upgraded Giant Metrewave Radio Telescope. The observations were carried out over a frequency range of 300–750 MHz, and on four different dates over a period of 6 months. Our analysis indicates that the fast radio bursts' emission properties are evolving, with both the median flux and emission rate of the bursts decreasing over time. The properties of the bursts also vary widely, with a wide range of intrinsic widths (0.246–39.364 ms), scattering timescales (0.004–28.289 ms), dispersion measures (524.07–533.56 pc cm −3 ), and band occupancies (9–180 MHz). The distribution for the waiting time, t wait , is bimodal, and follows a Weibull distribution, with a shape parameter k = 0.33; however, when the two distributions are fit separately, they follow a Weibull distribution with k = 0.63 for t wait < 1 s, and a log-normal distribution with a width of σ = 1.28 for t wait > 1 s. The isotropic energy distribution is seen to follow a log-normal distribution as well, with a width of σ = 0.83.}, archive = {J_ApJ}, author = {U. Panda and J. Roy and S. Bhattacharyya and C. Dudeja and S. Kudale}, doi = {10.3847/1538-4357/adeb74}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {15}, shortjournal = {The Astrophys. J.}, title = {Low-frequency, wideband study of an active repeater, FRB 20240114A, with the GMRT}, volume = {989}, year = {2025}, }
• (2025). Evaluation of multiparameter likelihoods through iteration of two-dimensional slices. ApJ, 989(1), 14. (www)

  @article{ , abstract = {In this paper we introduce a method for resolving multiparameter likelihoods by fixing all parameter values but two. Evaluation of those two variables is followed by iteratively cycling through each of the parameters in turn until convergence. We test the technique on the temperature power spectrum of the lensed cosmic microwave background. That demonstration is particularly effective since one of the six parameters that define the power spectra, the power spectrum amplitude, A s , nears linearity at small deviations, reducing computation to incrementation in one dimension, rather than over a two-dimensional (2D) grid. At each iterative step A s is paired with a different parameter. The iterative process yields parameter values in agreement with those derived by Planck, and results are obtained within a few hundred calls for spectra. We further compute parameter values as a function of maximum multipole, ℓ max , spanning a range from ℓ max = 959 to 2500 and uncover bimodal behavior at the lower end of that range. In the general case, in which neither variable is linear, we identify moderating factors, such as changing both parameters per each iterative step, and thereby reducing the number of steps per iteration. Markov Chain Monte Carlo (MCMC) computation has been the dominant instrument for evaluating multiparameter functions. For applications with a quasi-linear variable such as, A s , the 2D iterative method is orders of magnitude more efficient than MCMC.}, archive = {J_ApJ}, author = {Joel S. Jayson}, doi = {10.3847/1538-4357/adec99}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {14}, shortjournal = {The Astrophys. J.}, title = {Evaluation of multiparameter likelihoods through iteration of two-dimensional slices}, volume = {989}, year = {2025}, }
• (2025). SRG/eROSITA no. 5: Discovery of quasiperiodic eruptions every ∼3.7 days from a galaxy at z > 0.1. ApJ, 989(1), 13. (www)

  @article{ , abstract = {Quasiperiodic eruptions (QPEs) are repeating soft-X-ray bursts from the nuclei of galaxies, tantalizingly proposed to be extreme-mass-ratio inspirals. Here, we report the discovery of a new galaxy showing X-ray QPEs, the fifth found through a dedicated blind search of the Spectrum–Roentgen–Gamma/eROSITA all-sky survey data, hereafter named eRO-QPE5. Its QPE duration ( t dur ∼ 0.6 days), recurrence time ( t recur ∼ 3.7 days), integrated energy per eruption (∼3.4 × 10 47 erg), and black hole mass ( {M}_{{\rm{BH}}}=2.{9}_{-2.2}^{+5.4}\times 1{0}^{7}\,{M}_{\odot } ) sit at the high end of the known population. Like other eROSITA or X-ray-discovered QPEs, no previous or concurrent optical–IR transient is found in archival photometric data sets, and the optical spectrum looks almost featureless. With a spectroscopic redshift of 0.1155, eRO-QPE5 is the most distant QPE source discovered to date. Given the number of recent discoveries, we test for possible correlations and confirm a connection between t dur and t recur , while we do not find any significant correlation involving either M BH or the QPE temperature. The slope of the t dur – t recur relation (1.14 ± 0.16) is roughly consistent with predictions from star–disk collision models, with a preference for those suggesting that QPEs are powered by stellar debris streams around the orbiter. Considering this and previous discoveries, eROSITA has proved extremely successful in finding many QPE candidates, given its grasp—namely, its its sensitivity and large field of view—and scanning capabilities over the full sky. We advocate the need for sensitive wide-area- and time-domain-oriented surveys from future-generation soft-X-ray missions.}, archive = {J_ApJ}, author = {R. Arcodia and P. Baldini and A. Merloni and A. Rau and K. Nandra and J. Chakraborty and A. J. Goodwin and M. J. Page and J. Buchner and M. Masterson and I. Monageng and Z. Arzoumanian and D. Buckley and E. Kara and G. Ponti and M. E. Ramos-Ceja and M. Salvato and K. Gendreau and I. Grotova and M. Krumpe}, doi = {10.3847/1538-4357/adec9b}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {13}, shortjournal = {The Astrophys. J.}, title = {SRG/eROSITA no. 5: Discovery of quasiperiodic eruptions every ∼3.7 days from a galaxy at z > 0.1}, volume = {989}, year = {2025}, }
• (2025). Tidal debris candidates from the ω centauri accretion event and its role building up the milky way halo. ApJ, 989(1), 12. (www)

  @article{ , abstract = {We identify stellar tidal debris from the ω Centauri ( ω Cen) system among field stars in the Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey via chemical tagging using a neural network trained on APOGEE observations of the ω Cen core. We find a total of 463 ω Cen debris candidates have a probability P > 0.8 of sharing common patterns in their chemical abundances across a range of individual elements or element combinations, including [C+N], O, Mg, Al, Si, Ca, Ni, and Fe. Some debris candidates show prograde or retrograde disk-like kinematics, but most show kinematics consistent with the accreted halo, showing high radial actions, J R , values. We find that a sample of Gaia-Sausage-Enceladus (GES) members are chemically distinct from the ω Cen core, suggesting that ω Cen is associated with an independent merger event shaping the Milky Way halo. However, a connection between GSE and ω Cen cannot be ruled out. A detailed comparison with N -body simulations indicates that the ω Cen progenitor was a massive dwarf galaxy (≳10 8 M ⊙ ). The existence of a metal-poor high- α chemically homogeneous halo debris is also reported.}, archive = {J_ApJ}, author = {Borja Anguiano and Arik W. Mitschang and Takanobu Kirihara and Yutaka Hirai and Danny Horta and Sten Hasselquist and Ricardo P. Schiavon and Steven R. Majewski and Andrew C. Mason and Adrian M. Price-Whelan and Carlos Allende Prieto and Verne V. Smith and Katia Cunha and David L. Nidever}, doi = {10.3847/1538-4357/adda2c}, journal = {The Astrophysical Journal}, month = {8}, number = {1}, pages = {12}, shortjournal = {The Astrophys. J.}, title = {Tidal debris candidates from the ω centauri accretion event and its role building up the milky way halo}, volume = {989}, year = {2025}, }
• (2025). The ALMA survey of gas evolution of PROtoplanetary disks (AGE-PRO). XII. extreme millimeter variability detected in a class II disk. ApJ, 989(1), 11. (www)

  @article{ , abstract = {Variability of millimeter wavelength continuum emission from Class II protoplanetary disks is extremely rare, and when detected, it is usually interpreted as originating from nonthermal emission mechanisms that relate to the host star itself rather than its disk. During observations made as part of the AGE-PRO Large Program, significant variability in the brightness of the 2MASS J16202863-2442087 system was detected between individual executions. We report the observed properties of the variability detected at millimeter wavelengths and investigate potential driving mechanisms. To investigate the nature of the variability, we construct a light curve from the continuum observations and analyze images constructed from both flaring and quiescent emission. We characterize the dust disk around the star through analysis in the image and visibility plane, and carry out kinematic analysis of CO (2–1) emission from the gas disk. The continuum flux decays by a factor of 8 in less than an hour, and by a factor of 13 within 8 days. The peak brightness coincides with an expected brightness maximum extrapolated from the periodicity of previously observed optical variability. The flare is most likely the product of synchrotron emission in the close vicinity of the star. The nature of the millimeter flare closely resembles those detected in very close binary systems, and may be due to the interaction of magnetic fields in an as-yet undetected binary. Alternatively, if the central host is a single-star object, the flare may be due to the interaction of magnetic field loops at the stellar surface or a strong accretion burst.}, archive = {J_ApJ}, author = {James M. Miley and Laura M. Pérez and Carolina Agurto-Gangas and Anibal Sierra and Leon Trapman and Miguel Vioque and Nicolas Kurtovic and Paola Pinilla and Ilaria Pascucci and Ke Zhang and Rossella Anania and John Carpenter and Lucas A. Cieza and Dingshan Deng and Camilo González-Ruilova and Giovanni P. Rosotti and Dary A. Ruiz-Rodriguez and Estephani E. TorresVillanueva}, doi = {10.3847/1538-4357/add25c}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {11}, shortjournal = {The Astrophys. J.}, title = {The ALMA survey of gas evolution of PROtoplanetary disks (AGE-PRO). XII. extreme millimeter variability detected in a class II disk}, volume = {989}, year = {2025}, }
• (2025). The ALMA survey of gas evolution of PROtoplanetary disks (AGE-PRO). XI. beam-corrected gas disk sizes from fitting 12CO moment zero maps. ApJ, 989(1), 10. (www)

  @article{ , abstract = {The inward drift of millimeter–centimeter sized pebbles in protoplanetary disks has become an important part of our current theories of planet formation and, more recently, planet composition as well. The gas-to-dust size ratio of protoplanetary disks can provide an important constraint on how pebbles have drifted inward, provided that observational effects, especially resolution, can be accounted for. Here we present a method for fitting beam-convolved models to integrated intensity maps of line emission using the astropy Python package and use it to fit 12 CO moment zero maps of 10 Lupus and 10 Upper Scorpius protoplanetary disks from the ALMA Survey of Gas Evolution of PROtoplanetary Disks (AGE-PRO) Program, a sample of disks around M3-K6 stars that cover the  ∼1–6 Myr of gas disk evolution. From the unconvolved best fit models, we measure the gas disk size ( {R}_{{\rm{CO}},90 \% }^{{\rm{model}}} ), which we combine with the dust disk size ( {R}_{{\rm{dust}},90 \% }^{{\rm{FRANK}}} ) from continuum visibility fits from M. Vioque et al. to compute beam-corrected gas-to-dust size ratios. In our sample, we find gas-to-dust size ratios between  ∼1 and  ∼5.5, with a median value of 2.7{8}_{-0.32}^{+0.37} . Contrary to models of dust evolution that predict an increasing size ratio with time, we find that the younger disks in Lupus have similar (or even larger) median ratios (3.0{2}_{-0.33}^{+0.33}) than the older disks in Upper Sco (2.4{6}_{-0.38}^{+0.53}) . A possible explanation for this discrepancy is that pebble drift is halted in dust traps combined with truncation of the gas disk by external photoevaporation in Upper Sco, although survivorship bias could also play a role.}, archive = {J_ApJ}, author = {Leon Trapman and Miguel Vioque and Nicolás T. Kurtovic and Ke Zhang and Giovanni P. Rosotti and Paola Pinilla and John Carpenter and Lucas A. Cieza and Ilaria Pascucci and Rossella Anania and Carolina Agurto-Gangas and Dingshan Deng and James Miley and Laura M. Pérez and Anibal Sierra and Benoît Tabone and Dary A. Ruiz-Rodriguez and Camilo González-Ruilova and Estephani TorresVillanueva}, doi = {10.3847/1538-4357/adc7af}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {10}, shortjournal = {The Astrophys. J.}, title = {The ALMA survey of gas evolution of PROtoplanetary disks (AGE-PRO). XI. beam-corrected gas disk sizes from fitting 12CO moment zero maps}, volume = {989}, year = {2025}, }
• (2025). The ALMA survey of gas evolution of PROtoplanetary disks (AGE-PRO). x. dust substructures, disk geometries, and dust-disk radii. ApJ, 989(1), 9. (www)

  @article{ , abstract = {We perform visibility fitting to the dust continuum Band 6 1.3 mm data of the 30 protoplanetary disks in the Atacama Large Millimeter/submillimeter Array Survey of Gas Evolution of PROtoplanetary Disks (AGE-PRO) Large Program. We obtain disk geometries, dust-disk radii, and azimuthally symmetric radial profiles of the intensity of the dust continuum emission. We examine the presence of continuum substructures in the AGE-PRO sample by using these radial profiles and their residuals. We detect substructures in 15 out of 30 disks. We report five disks with large (>15 au) inner dust cavities. The Ophiuchus Class I disks show dust-disk substructures in ∼80% of the resolved sources. This evidences the early formation of substructures in protoplanetary disks. A spiral is identified in IRS 63, hinting to gravitational instability in this massive disk. We compare our dust-disk brightness radial profiles with gas-disk brightness radial profiles and discuss colocal substructures in both tracers. In addition, we discuss the evolution of dust-disk radii and substructures across Ophiuchus, Lupus, and Upper Scorpius. We find that disks in Lupus and Upper Scorpius with large inner dust cavities have typical gas-disk masses, suggesting an abundance of dust cavities in these regions. The prevalence of pressure dust traps at later ages is supported by a potential trend with time with more disks with large inner dust cavities (or transition disks ) in Upper Scorpius and the absence of evolution of dust-disk sizes with time in the AGE-PRO sample. We propose this is caused by an evolutionary sequence with a high fraction of protoplanetary disks with inner protoplanets carving dust cavities.}, archive = {J_ApJ}, author = {Miguel Vioque and Nicolás T. Kurtovic and Leon Trapman and Anibal Sierra and Laura M. Pérez and Ke Zhang and Pietro Curone and Giovanni P. Rosotti and John Carpenter and Benoît Tabone and Paola Pinilla and Dingshan Deng and Ilaria Pascucci and James Miley and Carolina Agurto-Gangas and Lucas A. Cieza and Rossella Anania and Dary A. Ruiz-Rodriguez and Camilo González-Ruilova and Estephani E. TorresVillanueva and Aleksandra Kuznetsova}, doi = {10.3847/1538-4357/adc7b0}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {9}, shortjournal = {The Astrophys. J.}, title = {The ALMA survey of gas evolution of PROtoplanetary disks (AGE-PRO). x. dust substructures, disk geometries, and dust-disk radii}, volume = {989}, year = {2025}, }
• (2025). The ALMA survey of gas evolution of PROtoplanetary disks (AGE-PRO). VIII. the impact of external photoevaporation on disk masses and radii in upper scorpius. ApJ, 989(1), 8. (www)

  @article{ , abstract = {Protoplanetary disk evolution can be deeply influenced by the UV radiation emitted by neighboring massive stars (mainly of spectral types O and B). We show that the process of external photoevaporation , which causes an outside-in depletion of disk material due to environmental UV radiation, can lead to a significant decrease in disk size, disk mass, and lifetime even at moderate irradiation levels (1–10 G 0 ). In this work, we investigate the role of external photoevaporation in shaping the masses and sizes of the 10 AGE-PRO disks in the Upper Scorpius (Upper Sco) region, which we estimate to be subject to far-ultraviolet (FUV) fluxes ranging between ∼2 and ∼12 G 0 , on average. We compare the disk masses and sizes resulting from 1D numerical viscous evolution simulations, in which the effect of external photoevaporation is included, to the values retrieved from the AGE-PRO observations. While the pure viscous framework fails in adequately explaining the observed disk properties in Upper Sco, with the inclusion of external photoevaporation, we can successfully reproduce gas disk sizes for seven out of 10 sources within a factor <2, when the initial disk mass is 1%–10% of the stellar mass. We emphasize the importance of accounting for the environmental irradiation when comparing star-forming regions of different ages, even when moderate FUV irradiation fields are experienced, as in the case of Upper Sco.}, archive = {J_ApJ}, author = {Rossella Anania and Giovanni P. Rosotti and Matías Gárate and Paola Pinilla and Miguel Vioque and Leon Trapman and John Carpenter and Ke Zhang and Ilaria Pascucci and Lucas A. Cieza and Anibal Sierra and Nicolas T. Kurtovic and James Miley and Laura M. Pérez and Benoît Tabone and Michiel Hogerheijde and Dingshan Deng and Carolina Agurto-Gangas and Dary A. Ruiz-Rodriguez and Camilo González-Ruilova and Estephani E. TorresVillanueva}, doi = {10.3847/1538-4357/adb587}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {8}, shortjournal = {The Astrophys. J.}, title = {The ALMA survey of gas evolution of PROtoplanetary disks (AGE-PRO). VIII. the impact of external photoevaporation on disk masses and radii in upper scorpius}, volume = {989}, year = {2025}, }
• (2025). The ALMA survey of gas evolution of PROtoplanetary disks (AGE-PRO). VII. testing accretion mechanisms from disk population synthesis. ApJ, 989(1), 7. (www)

  @article{ , abstract = {The architecture of planetary systems depends on the evolution of the disks in which they form. In this work, we develop a population synthesis approach to interpret the Atacama Large Millimeter/submillimeter Array survey of Gas Evolution of PROtoplanetary Disks (AGE-PRO) measurements of disk gas mass and size considering two scenarios: turbulence-driven evolution with photoevaporative winds and MHD wind-driven evolution. A systematic method is proposed to constrain the distribution of disk parameters from the disk fractions, accretion rates, disk gas masses, and CO gas sizes. We find that turbulence-driven accretion with initially compact disks ( R 0 ≃ 5–20 au), low mass-loss rates, and relatively long viscous timescales ( t ν ,0 ≃ 0.4–3 Myr or α SS ≃ 2–4 × 10 −4 ) can reproduce the disk fractions and gas sizes. However, the distribution of apparent disk lifetimes defined as the {M}_{D}/{\dot{M}}_{* } ratio is severely overestimated by turbulence-driven models. On the other hand, MHD wind-driven accretion can reproduce the bulk properties of disk populations from Ophiuchus to Upper Scorpius assuming compact disks with an initial magnetization of about β ≃ 10 5 ( α DW ≃ 0.5–1 × 10 −3 ) and a magnetic field that declines with time. More studies are needed to confirm the low masses found by AGE-PRO, notably for compact disks that question turbulence-driven accretion. The constrained synthetic disk populations can now be used for realistic planet population models to interpret the properties of planetary systems on a statistical basis.}, archive = {J_ApJ}, author = {Benoît Tabone and Giovanni P. Rosotti and Leon Trapman and Paola Pinilla and Ilaria Pascucci and Alice Somigliana and Richard Alexander and Miguel Vioque and Rossella Anania and Aleksandra Kuznetsova and Ke Zhang and Laura M. Pérez and Lucas A. Cieza and John Carpenter and Dingshan Deng and Carolina Agurto-Gangas and Dary A. Ruiz-Rodriguez and Anibal Sierra and Nicolás T. Kurtovic and James Miley and Camilo González-Ruilova and Estephani TorresVillanueva and Michiel R. Hogerheijde and Kamber Schwarz and Claudia Toci and Leonardo Testi and Giuseppe Lodato}, doi = {10.3847/1538-4357/adc7b1}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {7}, shortjournal = {The Astrophys. J.}, title = {The ALMA survey of gas evolution of PROtoplanetary disks (AGE-PRO). VII. testing accretion mechanisms from disk population synthesis}, volume = {989}, year = {2025}, }
• (2025). The ALMA survey of gas evolution of PROtoplanetary disks (AGE-PRO). VI. comparison of dust evolution models to AGE-PRO observations. ApJ, 989(1), 6. (www)

  @article{ , abstract = {The potential for planet formation of a circumstellar disk depends on the dust and gas reservoirs, which evolve as a function of the disk age. The Atacama Large Millimeter/submillimeter Array AGE-PRO Large Program has measured several disk properties across three star-forming regions of different ages, and in this study, we compare the observational results to dust evolution simulations. Using DustPy for the dust evolution, and RADMC-3D for the radiative transfer, we ran a large grid of models spanning stellar masses of 0.25, 0.50, 0.75, and 1.0 M ⊙ , with different initial conditions, including: disk sizes, disk gas masses, and dust-to-gas ratio, and viscosity. Our models are performed assuming smooth, weakly, or strongly substructured disks, aiming to investigate if any observational trend can favor or exclude the presence of dust traps. The observed gas masses in the disks of the AGE-PRO sample are not reproducible with our models, which only consider viscous evolution with constant α , suggesting that additional physical mechanisms play a role in the evolution of the gas mass of disks. When comparing the dust continuum emission fluxes and sizes at 1.3 mm, we find that most of the disks in the AGE-PRO sample are consistent with simulations that have either weak or strong dust traps. The evolution of spectral index in the AGE-PRO sample is also suggestive of an unresolved population of dust traps. Future observations at high angular resolution are still needed to test several hypotheses that result from comparing the observations to our simulations, including that more massive disks in gas mass have the potential to form dust traps at larger disk radii.}, archive = {J_ApJ}, author = {Nicolás T. Kurtovic and Matías Gárate and Paola Pinilla and Ke Zhang and Giovanni P. Rosotti and Rossella Anania and Ilaria Pascucci and Benoît Tabone and Leon Trapman and Dingshan Deng and Miguel Vioque and John Carpenter and Lucas A. Cieza and Laura M. Pérez and Carolina Agurto-Gangas and Anibal Sierra and Dary A. Ruiz-Rodriguez and James Miley and Camilo González-Ruilova and Estephani Torres-Villanueva and Aleksandra Kuznetsova}, doi = {10.3847/1538-4357/add1d0}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {6}, shortjournal = {The Astrophys. J.}, title = {The ALMA survey of gas evolution of PROtoplanetary disks (AGE-PRO). VI. comparison of dust evolution models to AGE-PRO observations}, volume = {989}, year = {2025}, }
• (2025). The ALMA survey of gas evolution of PROtoplanetary disks (AGE-PRO). v. protoplanetary gas disk masses. ApJ, 989(1), 5. (www)

  @article{ , abstract = {The evolution of the gas mass of planet-forming disks around young stars is crucial for our understanding of planet formation, yet it has proven hard to constrain observationally, due both to the difficulties of measuring gas masses and the lack of a homogeneous sample. Here we present a large grid of thermochemical models that we use to measure protoplanetary gas disk masses of AGE-PRO, the Atacama Large Millimeter/submillimeter Array survey of Gas Evolution in PROtoplanetary disks. AGE-PRO covers a sample of 30 disks around similar spectral type (M3-K6) stars with ages between 0.1 and 10 Myr. Our approach is to simultaneously fit observations of CO isotopologues and N 2 H + , a complementary molecule produced when CO freezes out. We find that the median gas mass of the three regions decreases over time, from 7.{0}_{-2.6}^{+4.4}\times 1{0}^{-3}\,{M}_{\odot } in Ophiuchus (≲1 Myr) to 9.{4}_{-3.4}^{+5.4}\times 1{0}^{-4}\,{M}_{\odot } for Lupus (∼1–3 Myr) and 6.{8}_{-2.8}^{+5.1}\times 1{0}^{-4}\,{M}_{\odot } for Upper Sco (∼2–6 Myr), with ∼1 dex scatter in gas mass in each region. We note that the gas mass distributions for Lupus and Upper Sco look very similar, which could be due to survivorship bias for the latter. The median bulk CO abundance in the CO emitting layer is found to be a factor ∼10 lower than the interstellar medium value but does not significantly change between Lupus and Upper Sco. From Lupus to Upper Sco, the median gas-to-dust mass ratio increases by a factor ∼3 from ∼40 to ∼120, suggesting efficient inward pebble drift and/or the formation of planetesimals.}, archive = {J_ApJ}, author = {Leon Trapman and Ke Zhang and Giovanni P. Rosotti and Paola Pinilla and Benoît Tabone and Ilaria Pascucci and Carolina Agurto-Gangas and Rossella Anania and John Carpenter and Lucas A. Cieza and Dingshan Deng and Camilo González-Ruilova and Michiel R. Hogerheijde and Nicolás T. Kurtovic and Aleksandra Kuznetsova and James Miley and Laura M. Pérez and Dary A. Ruiz-Rodriguez and Kamber Schwarz and Anibal Sierra and Estephani TorresVillanueva and Miguel Vioque}, doi = {10.3847/1538-4357/adcd6e}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {5}, shortjournal = {The Astrophys. J.}, title = {The ALMA survey of gas evolution of PROtoplanetary disks (AGE-PRO). v. protoplanetary gas disk masses}, volume = {989}, year = {2025}, }
• (2025). The ALMA survey of gas evolution of PROtoplanetary disks (AGE-PRO). IV. dust and gas disk properties in the upper scorpius star-forming region. ApJ, 989(1), 4. (www)

  @article{ , abstract = {The Atacama Large Millimeter/submillimeter Array (ALMA) large program AGE-PRO explores protoplanetary disk evolution by studying gas and dust across various ages. This work focuses on 10 evolved disks in Upper Scorpius, observed in dust continuum emission, CO and its isotopologues, and N 2 H + with ALMA Bands 6 and 7. Disk radii, from the radial location enclosing 68% of the flux, are comparable to those in the younger Lupus region for both gas and dust tracers. However, solid masses are about an order of magnitude below those in Lupus and Ophiuchus, while the dust spectral index suggests some level of dust evolution. These empirical findings align with a combination of radial drift, dust trapping, and grain growth into larger bodies. A moderate correlation between CO and continuum fluxes suggests a link between gas and dust content, through the increased scatter compared to younger regions, possibly due to age variations, gas-to-dust ratio differences, or CO depletion. Additionally, the correlation between C 18 O and N 2 H + fluxes observed in Lupus persists in Upper Scorpius, indicating a relatively stable CO gas abundance over the Class II stage of disk evolution. In conclusion, the AGE-PRO survey of Upper Scorpius disks reveals intriguing trends in disk evolution. The findings point toward potential gas evolution and the presence of dust traps in these older disks. Future high-resolution observations are needed to confirm these possibilities and further refine our understanding of disk evolution and planet formation in older environments.}, archive = {J_ApJ}, author = {Carolina Agurto-Gangas and Laura M. Pérez and Anibal Sierra and James Miley and Ke Zhang and Ilaria Pascucci and Paola Pinilla and Dingshan Deng and John Carpenter and Leon Trapman and Miguel Vioque and Giovanni P. Rosotti and Nicolas Kurtovic and Lucas A. Cieza and Rossella Anania and Benoît Tabone and Kamber Schwarz and Michiel R. Hogerheijde and Estephani E. TorresVillanueva and Dary A. Ruiz-Rodriguez and Camilo González-Ruilova}, doi = {10.3847/1538-4357/adc7ab}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {4}, shortjournal = {The Astrophys. J.}, title = {The ALMA survey of gas evolution of PROtoplanetary disks (AGE-PRO). IV. dust and gas disk properties in the upper scorpius star-forming region}, volume = {989}, year = {2025}, }
• (2025). The ALMA survey of gas evolution of PROtoplanetary disks (AGE-PRO). III. dust and gas disk properties in the lupus star-forming region. ApJ, 989(1), 3. (www)

  @article{ , abstract = {We present Band 6 and Band 7 observations of 10 Lupus disks around M3-K6 stars from the Atacama Large Millimeter/submillimeter Array survey of Gas Evolution in PROtoplanetary disks (AGE-PRO) Large Program. In addition to continuum emission in both bands, our Band 6 setup covers the 12 CO, 13 CO, and C 18 O J = 2–1 lines, while our Band 7 setup covers the N 2 H + J = 3–2 line. All of our sources are detected in 12 CO and 13 CO; seven out of ten are detected in C 18 O; and three are detected in N 2 H + . We find strong correlations between the CO isotopologue line fluxes and the continuum flux densities. With the exception of one disk, we also identify a strong correlation between the C 18 O J = 2–1 and N 2 H + J = 3–2 fluxes, indicating similar CO abundances across this sample. For the two sources with well-resolved continuum and 12 CO J = 2–1 images, we find that their gas-to-dust size ratio is consistent with the median value of ∼2 inferred from a larger sample of Lupus disks. We derive dust disk masses from continuum flux densities. We estimate gas disk masses by comparing C 18 O J = 2–1 line fluxes with those predicted by the limited grid of self-consistent disk models of M. Ruaud et al. A comparison of these mass estimates with those derived by L. Trapman et al., using a combination of CO isotopologue and N 2 H + line emission, shows that the masses are consistent with each other. Some discrepancies appear for small and faint disks, but they are still within the uncertainties. Both methods find gas disk masses increase with dust disk masses, and gas-to-dust mass ratios are between 10 and 100 in the AGE-PRO Lupus sample.}, archive = {J_ApJ}, author = {Dingshan Deng and Miguel Vioque and Ilaria Pascucci and Laura M. Pérez and Ke Zhang and Nicolás Kurtovic and Leon Trapman and Estephani E. TorresVillanueva and Carolina Agurto-Gangas and John Carpenter and Paola Pinilla and Uma Gorti and Benoît Tabone and Anibal Sierra and Giovanni P. Rosotti and Lucas A. Cieza and Rossella Anania and Camilo González-Ruilova and Michiel R. Hogerheijde and James Miley and Dary A. Ruiz-Rodriguez and Maxime Ruaud and Kamber Schwarz}, doi = {10.3847/1538-4357/add43a}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {3}, shortjournal = {The Astrophys. J.}, title = {The ALMA survey of gas evolution of PROtoplanetary disks (AGE-PRO). III. dust and gas disk properties in the lupus star-forming region}, volume = {989}, year = {2025}, }
• (2025). The ALMA survey of gas evolution of PROtoplanetary disks (AGE-PRO). II. dust and gas disk properties in the ophiuchus star-forming region. ApJ, 989(1), 2. (www)

  @article{ , abstract = {The ALMA survey of Gas Evolution in PROtoplanetary disks (AGE-PRO) Large Program aims to trace the evolution of gas disk mass and size throughout the lifetime of protoplanetary disks by using the Atacama Large Millimeter/submillimeter Array (ALMA). This paper presents Band-6 ALMA observations of 10 embedded (Class I and Flat Spectrum) sources in the Ophiuchus molecular cloud, with spectral types ranging from M3 to K6 stars, which serve as the evolutionary starting point in the AGE-PRO sample. While we find four nearly edge-on disks (≥70°), and three highly inclined disks (≥60 ° ) in our sample, we show that, as a population, embedded disks in Ophiuchus are not significantly contaminated by more-evolved, but highly inclined sources. We derived dust disk masses from the Band-6 continuum and estimated gas disk masses from the C 18 O J = 2−1 and C 17 O J = 2−1 lines. The mass estimates from the C 17 O line are slightly higher, suggesting C 18 O emission might be partially optically thick. While the 12 CO and 13 CO lines are severely contaminated by extended emission and self-absorption, the C 18 O and C 17 O lines are allowed to trace the radial extent of the gaseous disks. From these measurements, we found that the C 18 O J = 2−1 and C 17 O J = 2−1 fluxes correlate well with each other and with the continuum fluxes. Furthermore, the C 18 O and C 17 O lines present a larger radial extension than disk dust sizes by factors ranging from ∼1.5 to ∼2.5, as is found for Class II disks using the radial extension of the 12 CO. In addition, we have detected outflows in three disks from 12 CO observations.}, archive = {J_ApJ}, author = {Dary A. Ruiz-Rodriguez and Camilo González-Ruilova and Lucas A. Cieza and Ke Zhang and Leon Trapman and Anibal Sierra and Paola Pinilla and Ilaria Pascucci and Laura M. Pérez and Dingshan Deng and Carolina Agurto-Gangas and John Carpenter and Benoît Tabone and Giovanni P. Rosotti and Rossella Anania and James Miley and Kamber Schwarz and Aleksandra Kuznetsova and Miguel Vioque and Nicolas Kurtovic}, doi = {10.3847/1538-4357/add2ec}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {2}, shortjournal = {The Astrophys. J.}, title = {The ALMA survey of gas evolution of PROtoplanetary disks (AGE-PRO). II. dust and gas disk properties in the ophiuchus star-forming region}, volume = {989}, year = {2025}, }
• (2025). The ALMA survey of gas evolution of PROtoplanetary disks (AGE-PRO). i. program overview and summary of first results. ApJ, 989(1), 1. (www)

  @article{ , abstract = {We present the Atacama Large Millimeter/submillimeter Array Survey of Gas Evolution of PROtoplanetary Disks (AGE-PRO), a large program of the ALMA. AGE-PRO aims to systematically trace the evolution of gas disk mass and size throughout the lifetime of protoplanetary disks. It uses a carefully selected sample of 30 disks around M3-K6 stars in three nearby star-forming regions: Ophiuchus (0.5–1 Myr), Lupus (1–3 Myr), and Upper Sco (2–6 Myr). Assuming the three regions had similar initial conditions and evolutionary paths, we find the median gas disk mass appears to decrease with age. Ophiuchus disks have the highest median gas mass (6 M Jup ), while the Lupus and Upper Sco disks have significantly lower median masses (0.68 and 0.44 M Jup , respectively). Notably, the gas and dust disk masses appear to evolve on different timescales. This is evidenced by the median gas-to-dust mass ratio, which decreases from 122 in the youngest disks (<1 Myr) to 46 in Lupus disks, and then increases to 120 in the Upper Sco disks. The median gas disk sizes range between 74 and 110 au, suggesting that typical gas disks are much smaller than those of well-studied, massive disks. Population synthesis models suggest that magnetohydrodynamic wind-driven accretion can reproduce median disk properties across all three regions, when assuming compact disks with a declining magnetic field over time. In contrast, turbulent-driven models overestimate gas masses of >1 Myr disks by an order of magnitude. Here, we discuss the program’s motivation, survey design, sample selection, observation and data calibration processes, and highlight the initial results.}, archive = {J_ApJ}, author = {Ke Zhang and Laura M. Pérez and Ilaria Pascucci and Paola Pinilla and Lucas A. Cieza and John Carpenter and Leon Trapman and Dingshan Deng and Carolina Agurto-Gangas and Anibal Sierra and Nicolás T. Kurtovic and Dary A. Ruiz-Rodriguez and Miguel Vioque and James Miley and Benoît Tabone and Camilo González-Ruilova and Rossella Anania and Giovanni P. Rosotti and Estephani TorresVillanueva and Michiel R. Hogerheijde and Kamber Schwarz and Aleksandra Kuznetsova}, doi = {10.3847/1538-4357/addebe}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {1}, shortjournal = {The Astrophys. J.}, title = {The ALMA survey of gas evolution of PROtoplanetary disks (AGE-PRO). i. program overview and summary of first results}, volume = {989}, year = {2025}, }
• (2025). Detailed time-resolved spectral and temporal investigations of SGR j1550–5418 bursts detected with fermi gamma-ray burst monitor. ApJ, 988(2), 282. (www)

  @article{ , abstract = {We have conducted a time-resolved spectral analysis of magnetar bursts originating from SGR J1550−5418. Our analysis utilizes a two-step methodology for temporal segmentation of the data. We first generated and fitted overlapping time segments. Subsequently, we obtained nonoverlapping time segments with varying lengths based on their spectral evolution patterns, employing a machine learning algorithm called k -means clustering. For the fitting process, we employed three distinct models, namely a modified blackbody (MBB-RCS), a double blackbody (BB+BB), and a power law with an exponential cutoff (COMPT) model. We found that nearly all of the time segments fit well with the COMPT model. Both the average peak energy in the νF ν spectra ( E peak ) and photon index parameters follow a Gaussian distribution with means ∼30 keV and −0.5, respectively. Furthermore, there is a strong positive correlation between the cooler and hotter temperature parameters of the BB+BB model, and both parameters show a Gaussian distribution with peaks ∼4 and 12 keV, respectively. Additionally, we found that the distribution of the temperature parameter of the MBB-RCS model can be fit with a skewed Gaussian function with a peak ∼9–10 keV. Lastly, we searched for quasiperiodic spectral oscillations (QPSOs) in the hardness ratio evolution of the bursts. We identified five potential QPSO candidates at frequencies ranging from ∼15 to ∼68 Hz. We discuss and compare these results with previous studies.}, archive = {J_ApJ}, author = {Mustafa Demirer and Ersin Göğüş and Yuki Kaneko and Özge Keskin and Sinem Şaşmaz and Shotaro Yamasaki}, doi = {10.3847/1538-4357/ade237}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {282}, shortjournal = {The Astrophys. J.}, title = {Detailed time-resolved spectral and temporal investigations of SGR j1550–5418 bursts detected with fermi gamma-ray burst monitor}, volume = {988}, year = {2025}, }
• (2025). Timing results of 22 yr for PSR j0922+0638. ApJ, 988(2), 281. (www)

  @article{ , abstract = {We conducted a timing analysis of PSR J0922+0638 (B0919+06) using data from the Nanshan 26 m radio telescope and the MeerKAT telescope, spanning from 2001 January to 2023 March. During this 22 yr period, we discovered a previously unreported small glitch (glitch 1) before the well-known large glitch (glitch 2), occurring at MJD ∼ 53325(3), with a frequency jump amplitude of Δ ν / ν ∼ 0.79(6) × 10 −9 . We also identified 10 slow glitch events, half of which were newly detected. These slow glitches occurred quasi-periodically, with an average interval of approximately 553(21) days, fractional frequency changes ranging from Δ ν / ν ∼ 1.13(1) × 10 −9 to 4.08(5)×10 −9 , and a maximum fractional change in the first derivative of the frequency of {\rm{\Delta }}\dot{\nu }/\dot{\nu }\sim -4.6\times 1{0}^{-3} . Additionally, our timing noise analysis reveals a change in the spectral index for noise power before and after glitch 2, with values of −6.0 and −5.3, respectively, likely due to this large glitch. Throughout the entire observation period, the first derivative of the spin frequency ( \dot{\nu } ) showed a periodic structure. The possible modulation period was estimated to be 537(24) days before the 700 days data gap at MJD 56716 and 600(58) days afterward. We discuss the periodic oscillations in pulsar rotation as a possible manifestation of spin-down noise and quasi-periodic slow glitches.}, archive = {J_ApJ}, author = {Peng Liu and Mingyang Wang and Jianping Yuan and Zhonghao Tu and Ang Li and Xia Zhou and Na Wang}, doi = {10.3847/1538-4357/adeb78}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {281}, shortjournal = {The Astrophys. J.}, title = {Timing results of 22 yr for PSR j0922+0638}, volume = {988}, year = {2025}, }
• (2025). A new measure of assembly bias using the environment dependence of the luminosity function. ApJ, 988(2), 280. (www)

  @article{ , abstract = {Assembly bias is the variation in the clustering of dark matter halos and galaxies that arises from correlations between the halo assembly history and the large-scale environment at fixed halo mass. In this work, we use the cosmological magnetohydrodynamical simulation TNG300 to investigate how assembly bias affects the environment-dependent galaxy luminosity function (LF). We measure the LFs in bins of large-scale environment for the original simulated galaxy sample and for a shuffled sample, where the galaxies are randomly reassigned among halos of similar mass to remove assembly bias. By comparing them, we find distinct signatures, showing variations in the number of galaxies at the ∼10% level across all luminosities. Assembly bias increases the tendency of galaxies to reside in denser environments and further dilutes underdense regions, beyond the trends governed by halo mass. When separating by color, we see that assembly bias has a much bigger effect on red galaxies fainter than {M}_{r}-5\,{\mathrm{log}}\,h=-18.5 , which accounts for a ∼20% increase in the number of galaxies in the densest environment and a remarkable 50% decrease in the least dense regions. The ratio of these measurements for the densest and least dense regions provides a significant assembly bias signal for the faint red galaxies, larger than a factor of 2. Overall, our results provide a novel sensitive measure of assembly bias, offering valuable insight for modeling the effect and a potential new route to detect it in observations.}, archive = {J_ApJ}, author = {Yikun Wang and Idit Zehavi and Sergio Contreras and Shaun Cole and Peder Norberg}, doi = {10.3847/1538-4357/ade98b}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {280}, shortjournal = {The Astrophys. J.}, title = {A new measure of assembly bias using the environment dependence of the luminosity function}, volume = {988}, year = {2025}, }
• (2025). Magnification bias reveals severe contamination in hubble frontier field photo-z catalogs. ApJ, 988(2), 279. (www)

  @article{ , abstract = {Gravitational lensing by massive galaxy clusters enables faint distant galaxies to be more abundantly detected than in blank fields, thereby allowing one to construct galaxy luminosity functions (LFs) to an unprecedented depth at high redshifts. Intriguingly, photometric redshift catalogs constructed from the Hubble Frontier Fields survey display an excess of z ≳ 4 galaxies in the cluster lensing fields that is not seen in accompanying blank parallel fields. The observed excess, while possibly a gift of gravitational lensing, could also be from misidentified low- z contaminants having similar spectral energy distributions as high- z galaxies. In the latter case, the contaminants may result in nonphysical upturns in UV LFs and/or washed-out faint-end turnovers predicted by contender cosmological models to Lambda cold dark matter (ΛCDM). Here, we employ the concept of magnification bias to perform the first statistical estimation of contamination levels in Hubble Frontier Fields lensing field photometric redshift catalogs. While we were able to reproduce a lower- z lensed sample, it was found ∼56% of the 3.5 < z phot < 5.5 samples are likely low- z contaminants. Widely adopted Lyman-break-galaxy-like selection rules in the literature may give a “cleaner” sample magnification-bias-wise but we warn readers the resulting sample would also be less complete. Individual mitigation of contaminants is arguably the best way to investigate the faint high- z Universe, and this may be made possible with JWST observations.}, archive = {J_ApJ}, author = {Jiashuo Zhang and Jeremy Lim and Tom Broadhurst and Sung Kei Li and Man Cheung Li and Giorgio Manzoni and Rogier Windhorst}, doi = {10.3847/1538-4357/add7d5}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {279}, shortjournal = {The Astrophys. J.}, title = {Magnification bias reveals severe contamination in hubble frontier field photo-z catalogs}, volume = {988}, year = {2025}, }
• (2025). On the origins of “Hostless” supernovae: Testing the faint-end galaxy luminosity function and supernova progenitors with events in dwarf galaxies. ApJ, 988(2), 278. (www)

  @article{ , abstract = {We present arguments on the likely origins of supernovae without associated host galaxies from open field, nonclustered environments. We show why it is unlikely these “hostless” supernovae stem from escaped hypervelocity stars in any appreciable numbers, or the extreme outer halos of large galaxies, especially for core-collapse supernovae. It is highly likely that hostless events arise from dwarf host galaxies too faint to be detected in their parent surveys. Several detections and numerous upper limits suggest a large number of field dwarfs, to M V > −14, which themselves may be important to constraining the slope of the low-mass end of the UV luminosity function, understanding galaxy evolution, and putting Lambda cold dark matter (ΛCDM) into context. Moreover, the detailed study of these mass- and metallicity-constrained host environments, and the variety of supernovae that occur within them, could provide more stringent constraints on the nature of progenitor systems.}, archive = {J_ApJ}, author = {Louis-Gregory Strolger and Mia Sauda Bovill and Eric Perlman and Craig Kolobow and Conor Larison and Zachary G. Lane}, doi = {10.3847/1538-4357/ade43a}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {278}, shortjournal = {The Astrophys. J.}, title = {On the origins of “Hostless” supernovae: Testing the faint-end galaxy luminosity function and supernova progenitors with events in dwarf galaxies}, volume = {988}, year = {2025}, }
• (2025). H i absorption line and anomalous dispersion in the radio pulses of PSR b1937+21. ApJ, 988(2), 277. (www)

  @article{ , abstract = {We use the Five-hundred-meter Aperture Spherical radio Telescope to observe the bright millisecond pulsar PSR B1937+21 (J1939+2134) and record the data in the band from 1.0 to 1.5 GHz. We measure the neutral hydrogen (H I ) emission and absorption lines near 1420 MHz ( λ ≃ 21 cm). We derive the kinematic distance of the pulsar with the H I observation. By comparing this with the archival absorption spectra observed decades ago, we notice possible variations in the absorption spectra toward this pulsar, which correspond to a possible tiny-scale atomic structure of a few astronomical units in size. We also verify the apparent faster-than-light anomalous dispersion at the H I absorption line of this pulsar previously reported.}, archive = {J_ApJ}, author = {Jinchen Jiang and Shunshun Cao and Kejia Lee and Bojun Wang and Heng Xu and Siyuan Chen and Yanjun Guo and Peng Jiang and Weicong Jing and Jiguang Lu and Jiangwei Xu and Renxin Xu and Zihan Xue}, doi = {10.3847/1538-4357/ade70b}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {277}, shortjournal = {The Astrophys. J.}, title = {H i absorption line and anomalous dispersion in the radio pulses of PSR b1937+21}, volume = {988}, year = {2025}, }
• (2025). Persistent radio sources associated with fast radio bursts: Implications from magnetar progenitors. ApJ, 988(2), 276. (www)

  @article{ , abstract = {The rare association of three persistent radio sources (confirmed PRS1 and PRS2, candidate PRS3) with repeating fast radio bursts (FRB 20121102A, 20190520B, 20201124A) offers a unique probe into their magneto-ionic environments. PRSs are attributed to synchrotron emission from relativistic charged particles of a magnetar wind nebula (MWN), powered by spin-down magnetohydrodynamic wind or internal magnetic field decay. Using a multizone hydrodynamic model, we track MWN evolution to constrain magnetar progenitor properties. For PRS1 and PRS2, we find an equipartition radius R eq ∼ 0.1 pc that is consistent with the radio scintillation estimates (>0.03 pc) and radio imaging limits (<0.7 pc). This compact size favors low expansion speeds and large initial spin periods, P i ≳ 10 ms, ruling out millisecond magnetar progenitors. Given P i ≳ 10 ms, a current size of ∼0.1 pc, a supernova kinetic energy {E}_{\mathrm{SN}}\sim 1{0}^{50}\mbox{--}1{0}^{51} erg, and an ejecta mass M ∼ 3–10 M ⊙ , the PRS age is t ∼ 10–10 2 yr. PRSs with t > 20 yr require an internal field ( B int ∼ 10 16 –10 16.5 G) with a decay timescale t d ∼ 10–10 2.5 yr. The slowest field decay ( {t}_{{\rm{d}},{\rm{\max }}}\sim 500 yr) favors subenergetic supernovae ( {E}_{{\rm{SN}}}\sim 1{0}^{50}\ erg) with massive ejecta ( M ≳ 10 M ⊙ ) and a low-ionization fraction (∼3%). For the subenergetic scenario, for the confirmed PRSs, we predict a cooling break at 100–150 GHz at 20–40 μ Jy and self-absorption near 200 MHz at 180 μ Jy. For PRS3, a rotation-powered MWN is viable only if t ∼ 10 yr; an inverted spectrum beyond 150 GHz would rule out this scenario.}, archive = {J_ApJ}, author = {Sk. Minhajur Rahaman and Sandeep Kumar Acharya and Paz Beniamini and Jonathan Granot}, doi = {10.3847/1538-4357/ade70c}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {276}, shortjournal = {The Astrophys. J.}, title = {Persistent radio sources associated with fast radio bursts: Implications from magnetar progenitors}, volume = {988}, year = {2025}, }
• (2025). Magellanic accretion-powered pulsars studied via an unscented kalman filter. ApJ, 988(2), 275. (www)

  @article{ , abstract = {Magnetized high-mass X-ray binary pulsars accreting from a surrounding disk have been recently studied by a time-dependent Kalman filter (KF) model of accretion capable of studying correlations between dynamical variables and producing time series of their behaviors. We return to the intrinsic KF equations that describe the accretion process, and we rewrite them in simpler forms that allow for straightforward interpretations and a deeper understanding of the KF output data. We describe the influence of the KF defined frequencies β 1 , β 2 , and γ Ω , and we investigate the surface dipolar magnetic fields of 24 Magellanic pulsars produced by the KF analysis in comparison to the values obtained from standard accretion theory using the long-term trending changes of the pulsar spin periods (known as the long-term P-dot values). Good agreement is obtained over a wide range of pulsar spin periods when the KF magnetic field values are scaled down to the propeller regime by a factor of \sqrt{1-{\omega }_{s}\,} , where ω s = β 2 / β 1 is the fastness parameter that also distinguishes the regime of “stable polar” accretion ( ω s > 0.6) from Rayleigh–Taylor-driven “two-tongue equatorial” ( ω s < 0.45) matter inflow.}, archive = {J_ApJ}, author = {Dimitris M. Christodoulou and Joseph O’Leary and Andrew Melatos and Tom Kimpson and Sayantan Bhattacharya and Nicholas J. O’Neill and Silas G. T. Laycock and Demosthenes Kazanas}, doi = {10.3847/1538-4357/ade87b}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {275}, shortjournal = {The Astrophys. J.}, title = {Magellanic accretion-powered pulsars studied via an unscented kalman filter}, volume = {988}, year = {2025}, }
• (2025). On fast-radio-burst-associated X-ray bursts: Inverse compton scattering of radio photons by an extreme pair flow during magnetosphere activities. ApJ, 988(2), 274. (www)

  @article{ , abstract = {The Galactic fast radio burst (FRB) FRB 200428 was associated with a short X-ray burst (XRB) from the magnetar SGR J1935+2154 during one of its active phases. This FRB-associated XRB exhibits distinct properties compared to other typical XRBs, including a significantly higher cutoff energy and a steeper power-law index. Its recovered X-ray light curve shows a multiple-peak structure, with the time of arrival offset from that of the FRB. These unique features imply a special physical link between the FRB and X-ray emissions. In 2022 October, a similar FRB–XRB association was detected from the same source. In this paper, we propose a model in which the observed spectral and temporal features of the associated XRBs can be attributed to the inverse Compton scattering (ICS) of FRB photons by an extreme pair flow around the light cylinder, with a bulk Lorentz factor of Γ ∼ 10 and a power-law distribution in the comoving frame, characterized by a typical Lorentz factor {\gamma }_{{\rm{m}}}^{{\prime} }\sim 5\times 1{0}^{4} . This extreme pair flow could originate from the compression of a transient pulse of ∼10 40 −10 41 erg s −1 and the acceleration through magnetic reconnection in the current sheet during magnetar activity. The Doppler-boosted ICS spectra and the arrival time shifts in such a scenario can well explain the observed features of the FRB 200428–associated XRB and can also account for another associated event in 2022.}, archive = {J_ApJ}, author = {Yue Wu and Yuan-Pei Yang and Fa-Yin Wang and Zi-Gao Dai}, doi = {10.3847/1538-4357/ade884}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {274}, shortjournal = {The Astrophys. J.}, title = {On fast-radio-burst-associated X-ray bursts: Inverse compton scattering of radio photons by an extreme pair flow during magnetosphere activities}, volume = {988}, year = {2025}, }
• (2025). The virial factor f of the hβ broad line for NGC 5548 and NGC 4151. ApJ, 988(2), 273. (www)

  @article{ , abstract = {The variability of virial factor f is investigated for two active galactic nuclei, NGC 5548 and NGC 4151, which had been previously reverberation mapped (RM) over 20 times in the past 30 yr. Using four velocity tracers from the broad H β width at half-maximum (FWHM H β ) or the line dispersion from the mean or rms spectra, f for each RM epoch is calculated. Significant correlations are found between f and observational parameters, such as the broad-line widths, the Eddington ratios, and the line profile shapes. For NGC 5548, f\propto {{\rm{FWHM}}}_{{\rm{mean}}}^{-0.70\pm 0.13} and for NGC 4151, f\propto {{\rm{FWHM}}}_{{\rm{mean}}}^{-3.31\pm 0.59} . This suggests that a variable f should be included to weight the virial supermassive black hole mass. Using a simple model of thick-disk broad-line regions (BLRs), we show that changes in mean inclination can explain f variation. The inclination range is 14 \mathop{.}\limits^{\unicode{x000b0}} 1−40 \mathop{.}\limits^{\unicode{x000b0}} 6 for NGC 5548 and 14 \mathop{.}\limits^{\unicode{x000b0}} 0−55 \mathop{.}\limits^{\unicode{x000b0}} 1 for NGC 4151. Modeling the light curves of f with a damped random walk process yields mean timescales of 638 and 668 days, consistent with BLR dynamical timescales within uncertainties. This indicates that f variations are linked to BLR dynamics, likely due to changes in geometry or inclination.}, archive = {J_ApJ}, author = {Shao-Jun Li and Xiang-Wei Ning and Yan-Song Ma and Yi Tang and Wei-Hao Bian}, doi = {10.3847/1538-4357/adea4b}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {273}, shortjournal = {The Astrophys. J.}, title = {The virial factor f of the hβ broad line for NGC 5548 and NGC 4151}, volume = {988}, year = {2025}, }
• (2025). The proper motion of strongly lensed binary neutron star mergers in LIGO/Virgo/Kagra can be constrained by measuring doppler-induced gravitational-wave dephasing. ApJ, 988(2), 272. (www)

  @article{ , abstract = {Strongly lensed binary neutron star (NS–NS) mergers are expected to be observed once LIGO/Virgo/Kagra reaches the planned A+ or proposed A# sensitivity. We demonstrate that the relative transverse velocity of the source-lens system can be constrained by comparing the phase of the two associated gravitational wave (GW) images, using both semianalytical and numerical Bayesian methods. For A+ sensitivity, a 1 σ NS–NS merger signal in magnification ( μ = 200) and redshift ( z S = 1) will carry a marginally detectable dephasing signature for a source transverse velocity of ∼1800 km s −1 . This is comparable to the velocity dispersion of large galaxy clusters. Assuming the same population distribution, the most likely source parameters of μ = 100 and z S = 1.4 are always expected to showcase detectable dephasing imprints for A# sensitivity, provided they are moving with transverse velocities larger than ∼ 2000 km s −1 . We conclude that a first measurement of the relative transverse velocity of a source via GW dephasing methods is likely only a few years away.}, archive = {J_ApJ}, author = {Lorenz Zwick and Johan Samsing}, doi = {10.3847/1538-4357/adea54}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {272}, shortjournal = {The Astrophys. J.}, title = {The proper motion of strongly lensed binary neutron star mergers in LIGO/Virgo/Kagra can be constrained by measuring doppler-induced gravitational-wave dephasing}, volume = {988}, year = {2025}, }
• (2025). Luminosity function of galaxies in voids: A modification inspired by excursion set theory. ApJ, 988(2), 271. (www)

  @article{ , abstract = {In the standard picture of cosmology, the galaxies reside in dark matter (DM) halos. DM halos are distributed in the cosmic web in different environments. The luminosity of the galaxies in different environments can be used as a probe to assess a cosmological model. This study focuses on the properties of galaxies in void regions, where halos typically do not experience extreme conditions. By examining the galaxy luminosity function, we aim to understand the dependence of galaxy properties on their environment and redshift so that later, we can use this as a tool to evaluate cosmological models. We employ the excursion set theory to incorporate parameters related to the number density of DM halos into the luminosity function. Using the Galaxy and Mass Assembly survey and 2dFGRS data sets, we fit our theoretical models to observational data, examining the environmental and redshift dependence of the galaxy luminosity function. Our results indicate that we model the galaxy luminosity function in voids effectively by considering the linear density contrast of the environment and the growth function D ( z ) for redshift dependence. This study provides a model for the environmental dependence of galaxy luminosity function that offers an improvement in the χ 2 parameter compared to the previously proposed model in T. McNaught-Roberts et al. Both Bayesian information criterion (BIC) and Akaike information criterion (AIC) tests support the superiority of this model for the void region.}, archive = {J_ApJ}, author = {Zeynab Ashurikisomi and Shant Baghram}, doi = {10.3847/1538-4357/adeb80}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {271}, shortjournal = {The Astrophys. J.}, title = {Luminosity function of galaxies in voids: A modification inspired by excursion set theory}, volume = {988}, year = {2025}, }
• (2025). On the nature of the bright front of solar coronal mass ejections. ApJ, 988(2), 270. (www)

  @article{ , abstract = {A new explanation has been proposed on the nature of the three-part (bright core, dark cavity, and bright front) structure of coronal mass ejections (CMEs). It suggests that the bright front originates from the plasma pileup along the overlying coronal loops rather than the boundary of the magnetic flux rope at the early eruption stage. This has been confirmed with an active-region event through the direct comparison between the EUV loops and the CME front. However, large-scale EUV loops are hardly observed outside of strong active regions; thus, the front nature remains unclear for CMEs from quiet-Sun regions or weak active regions. In this paper, we address this issue through an intermediate filament eruption from a plage region without sunspots on 2024 March 30. Combining the overlapping observations of the Atmospheric Imaging Assembly and K-Coronagraph, we find that the overlying coronal loops appear gradually in EUV images during the filament eruption. The compressed loops and the plasma pileup along the loops (171 Å) correspond to the CME front in white-light images, which is essentially similar to the situation of events from strong active regions. Therefore, we believe that the explanation on the CME front holds true regardless of whether the EUV loops are visible or not prior to the eruption, and it works for events from different regions, including active regions and quiet-Sun regions. The reasons why the density evolution with height does not support or deny the pileup are discussed.}, archive = {J_ApJ}, author = {Hongqiang Song and Rui Wang and Leping Li and Bing Wang and Yao Chen}, doi = {10.3847/1538-4357/adec88}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {270}, shortjournal = {The Astrophys. J.}, title = {On the nature of the bright front of solar coronal mass ejections}, volume = {988}, year = {2025}, }
• (2025). Cosmic-ray diffusion in the turbulent interstellar medium: Effects of mirror diffusion and pitch-angle scattering. ApJ, 988(2), 269. (www)

  @article{ , abstract = {Cosmic rays (CRs) interact with turbulent magnetic fields in the interstellar medium (ISM), generating nonthermal emission. After many decades of studies, the theoretical understanding of their diffusion in the ISM continues to pose a challenge. This study numerically explores a recent prediction termed “mirror diffusion” and its synergy with the traditional diffusion mechanism based on gyroresonant scattering. Our study combines 3D MHD simulations of star-forming regions with test particle simulations to analyze CR diffusion. We demonstrate the significance of mirror diffusion in CR diffusion parallel to the magnetic field when the mirroring condition is satisfied. Our results support the theoretical expectation that the resulting particle propagation arising from mirror diffusion in combination with much faster diffusion induced by gyroresonant scattering resembles a Levy-flight-like propagation. Our study highlights the necessity to reevaluate the diffusion coefficients traditionally adopted in the ISM based on gyroresonant scattering alone. For instance, our simulations imply a diffusion coefficient ∼10 27 cm 2 s –1 for particles with a few hundred TeV within regions spanning a few parsecs around the source. This estimate is in agreement with gamma-ray observations, which show the relevance of our results for the understanding of gamma-ray emission in star-forming regions.}, archive = {J_ApJ}, author = {Lucas Barreto-Mota and Elisabete M. de Gouveia Dal Pino and Siyao Xu and Alexandre Lazarian}, doi = {10.3847/1538-4357/ade4c8}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {269}, shortjournal = {The Astrophys. J.}, title = {Cosmic-ray diffusion in the turbulent interstellar medium: Effects of mirror diffusion and pitch-angle scattering}, volume = {988}, year = {2025}, }
• (2025). Two-component γ-ray emission spectrum and X-ray polarization of the radio galaxy pictor a. ApJ, 988(2), 268. (www)

  @article{ , abstract = {Pictor A is a γ -ray emitting radio galaxy and has a bright hotspot called the western hotspot (WHS), located ∼4′ away from the nucleus. In this work, we present an analysis of its 16 yr Fermi Large Area Telescope (LAT) data and report the Imaging X-ray Polarimetry Explorer (IXPE) observations for this source. Our analysis of the Fermi-LAT observations reveals evidence of two components in the average γ -ray spectrum of Pictor A, exhibiting a statistically significant hardening from Γ γ ,1 = 3.25 ± 0.15 to Γ γ ,2 = 1.81 ± 0.07 at a break energy of 2.46 ± 0.09 GeV. Notably, variability of γ -rays is evident in Pictor A, predominantly driven by the component below the break energy, while the component above the break energy remains stable. Furthermore, our analysis reveals that a power-law function provides an adequate fit for the high-flux-state spectrum, while a broken-power-law function remains necessary to accurately model the low-flux-state spectrum. We suggest that the low-energy component originates from the nucleus, while the high-energy component primarily stems from WHS. The broadband spectral energy distributions of both nucleus and WHS can be well represented by a simple leptonic model, with both γ -ray components attributed to the synchrotron self-Compton (SSC) process. Analysis of IXPE data provides upper limits on the polarization degree of Π X < 6.6% for the nucleus and Π X < 56.4% for the WHS within the 2–8 keV band. For the nucleus, this result aligns with X-ray emission originating from the SSC process. However, the upper limit of Π X < 56.4% for WHS is insufficient to conclusively determine the X-ray emission mechanism in this region.}, archive = {J_ApJ}, author = {Jia-Xuan Li and Xin-Ke Hu and Ji-Shun Lian and Yu-Wei Yu and Wei Deng and Kuan Liu and Hai-Ming Zhang and Liang Chen and Jin Zhang}, doi = {10.3847/1538-4357/ade808}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {268}, shortjournal = {The Astrophys. J.}, title = {Two-component γ-ray emission spectrum and X-ray polarization of the radio galaxy pictor a}, volume = {988}, year = {2025}, }
• (2025). Elastic planetoids. ApJ, 988(2), 267. (www)

  @article{ , abstract = {Modeling the internal structure of self-gravitating solid and liquid bodies presents a challenge, as existing approaches are often limited to either overly simplistic constant-density approximations or more complex numerical equations of state (EOSs). We present a detailed analysis of a tractable and physically motivated model for perfectly elastic, spherically symmetric self-gravitating bodies in hydrostatic equilibrium. The model employs a logarithmic equation of state (often referred to as a logotropic EOS) with a nonzero initial density and constant bulk modulus. Importantly, the scaling properties of the model allow all solutions to be derived from a single, universal solution of an ordinary differential equation, resembling the Lane–Emden and Chandrasekhar models. The model provides new insights into stability issues and reveals oscillatory asymptotic behavior in the mass–radius relation, including the existence of both a maximum mass and a maximum radius. We derive useful, simple analytical approximations for key properties, such as central overdensity, moment of inertia, binding energy, and gravitational potential, applicable to small, metallic bodies like asteroids and moons. These new approximations could aid future research, including space mining and the scientific characterization of small solar system bodies.}, archive = {J_ApJ}, author = {Bartosz Żbik and Andrzej Odrzywołek}, doi = {10.3847/1538-4357/ade8ef}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {267}, shortjournal = {The Astrophys. J.}, title = {Elastic planetoids}, volume = {988}, year = {2025}, }
• (2025). The importance of tidal forces in molecular cloud dynamics. ApJ, 988(2), 266. (www)

  @article{ , abstract = {We investigate the role of tidal forces in molecular cloud formation by examining how apparent boundedness, as diagnosed by the classical virial parameter, relates to the actual gravitational state of clouds subject to tidal forces from their environment. Clouds are identified by a dendrogram algorithm in zoom-in regions taken from a simulation of a Milky Way–mass galaxy with the Voronoi mesh code AREPO that resolves star-forming regions at subparsec resolution. To look at a range of environments, we use data from three different regions that evolve differently in the center, near the equivalent of the solar circle, and the outskirts of the modeled galaxy, at three different times, each spaced 2 Myr apart. We compute the importance of tidal forces on all identified clouds. We then compare the boundedness of clouds, including only their internal potentials, to boundedness also including the external gravitational potential. This comparison shows that tidal forces can unbind apparently bound clouds and bind apparently unbound clouds. We characterize the cloud population by comparing their virial parameters to their surface densities, finding the ratio of the maximum to the minimum eigenvalues of the tidal tensor, and determining the strength of gravitational instability in each examined region. We find that it is necessary to take the total gravitational potential into account rather than just the internal self-gravity of the clouds to have an accurate understanding of cloud dynamics.}, archive = {J_ApJ}, author = {JinWoo Lee and Alexa Saur and Mordecai-Mark Mac Low and Hui Li}, doi = {10.3847/1538-4357/ade8f6}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {266}, shortjournal = {The Astrophys. J.}, title = {The importance of tidal forces in molecular cloud dynamics}, volume = {988}, year = {2025}, }
• (2025). A statistical analysis of magnetic parameters in solar source regions of halo coronal mass ejections with and without solar energetic particle events. ApJ, 988(2), 265. (www)

  @article{ , abstract = {Large solar energetic particles (SEPs) can cause adverse space weather hazards to human technology, and such events are especially associated with halo coronal mass ejections (CMEs). But in turn, a significant portion of halo CMEs are not associated with large SEPs. The objective of this study is to gain an understanding of the source region distinctions between halo CMEs in SEP and non-SEP events. Among the 176 halo CMEs observed from 2010 to 2024, we screen out 45 large SEP events and 131 non-SEP events from this data set. It is revealed that CME speed is a good discriminator between SEP and non-SEP events. Through classifying the source regions of all the halo CMEs, we find that 53% of SEP events originate from “single AR (active region),” and 47% from “multiple ARs” or “outside of ARs.” The corresponding proportion for non-SEP events is 70% and 30%. This suggests that SEP source regions are more likely to originate from large-scale sources. We have also calculated the relevant magnetic parameters of the source regions and found that SEP source regions have higher magnetic free energy and reconnection flux compared to non-SEP source regions. However, SEP source regions are smaller in terms of the intensive magnetic parameters such as mean characteristic magnetic twist α and mean shear angles. Our statistical results can provide new potential variables for forecasting SEPs.}, archive = {J_ApJ}, author = {Xuchun Duan and Ting Li and Yijun Hou and Yang Wang and Yue Li and Yining Zhang and Zheng Sun and Guiping Zhou}, doi = {10.3847/1538-4357/ade9af}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {265}, shortjournal = {The Astrophys. J.}, title = {A statistical analysis of magnetic parameters in solar source regions of halo coronal mass ejections with and without solar energetic particle events}, volume = {988}, year = {2025}, }
• (2025). Explaining JWST counts with galaxy formation models. ApJ, 988(2), 264. (www)

  @article{ , abstract = {A distinct power-law break is apparent at m AB ∼ 21 in the deep near-infrared PEARLS-JWST galaxy counts. The break becomes more pronounced at longer wavelengths, with the slope flattening smoothly with apparent magnitude in the shortest band used at 0.9 μ m, and trending toward an increasingly broken slope by the longest wavelength passband of JWST’s Near Infrared Camera, 4.4 μ m. This behaviour is remarkably well predicted by the GALFORM semi-analytical model of galaxy formation. We use the model to diagnose the origin of this behaviour. The features that are responsible for the break are (1) the inherent break in the luminosity function (LF); (2) the change in the volume element with redshift; (3) the redshift-dependent nature of the k -correction (with 1 contributing to the existence of the break and 2–3 contributing to its shape). We study the contribution to these effects by their morphology using the bulge-to-total stellar mass ratio. The way in which bulge-dominated galaxies populate the bright end of the LF while disk-dominated galaxies dominate the faint end is preserved in the galaxy number counts, with a characteristic stellar mass at a break of ∼10 10 M ⊙ . The shape of the number counts is mainly driven by galaxies with relatively low redshift ( z ≲ 2) for a limit of m AB ≲ 28. We give a comprehensive description of why the galaxy number counts in the near-infrared PEARLS-JWST observation look the way they do and which population of galaxies is dominant at each apparent magnitude.}, archive = {J_ApJ}, author = {Giorgio Manzoni and Tom Broadhurst and Jeremy Lim and Tao Liu and George Smoot and Carlton M. Baugh and Scott Tompkins and Rogier Windhorst and Simon Driver and Timothy Carleton and Brenda Frye and Leo Fung and Jiashuo Zhang and Seth H. Cohen and Christopher J. Conselice and Norman A. Grogin and Rolf A. Jansen and Anton M. Koekemoer and Rafael Ortiz and Norbert Pirzkal and Christopher N. A. Willmer}, doi = {10.3847/1538-4357/ade700}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {264}, shortjournal = {The Astrophys. J.}, title = {Explaining JWST counts with galaxy formation models}, volume = {988}, year = {2025}, }
• (2025). Diffuse X-ray-emitting gas in the central region of star-forming galaxies. ApJ, 988(2), 263. (www)

  @article{ , abstract = {The interstellar medium of galaxies, with temperatures reaching several million degrees, provides a pivotal perspective for understanding the physical and chemical properties of star formation, galactic evolution, and their associated feedback mechanisms. We use archival data from Chandra observations to extract the diffuse X-ray emission from 23 nearby star-forming galaxies and study its correlation with star formation activity in the central region of these galaxies. The surface brightness profile of each galaxy presents a sharp decrease in the central region of ∼0.3−2 kpc and then varies slowly outside this range. Compared to the global relation between the diffuse thermal X-ray luminosity from hot gas ( {L}_{0.5-2\,{\rm{keV}}}^{{\rm{gas}}} ) and the star formation rate (SFR), we found a superlinear relation of {\rm{log}}({L}^{{{\rm{gas}}}_{0}.5-2\,{\rm{keV}}}/{\rm{erg}}\,{{\rm{s}}}^{-1}) = 1.34\,{\rm{log}}({\rm{SFR}}/{M}_{\odot }\,{{\rm{yr}}}^{-1})+40.15 for the center of these sample galaxies. This result suggests that more intense stellar feedback is associated with stronger star formation activity in the central region of star-forming galaxies, where more energy output from supernovae and stellar winds is converted into X-ray flux. Furthermore, the slope of the {L}_{0.5-2\,{\rm{keV}}}^{{\rm{gas}}} –SFR relation anticorrelates with spatial scale in the galactic central region. This indicates that the characteristics of central hot gas emission are gradually averaged over larger areas. The diffuse X-ray luminosity also shows a good correlation with molecular gas, stellar mass, and midplane pressure traced by the baryonic mass, although these relations show relatively large scatter.}, archive = {J_ApJ}, author = {Chunyi Zhang and Junfeng Wang}, doi = {10.3847/1538-4357/ade71a}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {263}, shortjournal = {The Astrophys. J.}, title = {Diffuse X-ray-emitting gas in the central region of star-forming galaxies}, volume = {988}, year = {2025}, }
• (2025). Solar modulation of galactic cosmic rays from hydrogen to nickel based on a modified force-field approach. ApJ, 988(2), 262. (www)

  @article{ , abstract = {Galactic cosmic rays (GCRs), consisting predominantly of fully stripped nuclei, are significantly modulated by solar activity and represent a major radiation hazard for long-duration human space exploration. This study presents a comprehensive GCR modulation model based on a modified force-field approach, extending previous work by Z. Shen et al. to heavier nuclei. The local interstellar spectra (LIS) for elements from hydrogen to nickel are derived by fitting observations from Voyager, Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics, Alpha Magnetic Spectrometer-02, Advanced Composition Explorer Cosmic Ray Isotope Spectrometer, HEAO3-C2, and others. The solar modulation potential ϕ ( E ) is described by a double power-law function with an exponential tail. Due to differences in LIS spectral shapes and mass-to-charge ratio-dependent modulation effects, protons and helium have distinct ϕ values, while heavier nuclei share the same ϕ as helium. The time-dependent parameters within the ϕ expression are determined by fitting selected GCR measurements and subsequently reconstructed using sunspot number, heliospheric current sheet tilt angle, and heliospheric magnetic field polarity, enabling the development of a predictive GCR model. The results successfully reproduce the 11 and 22 yr GCR cycles, with good agreement with observations since Solar Cycle 19 across different particle species and energies. Additionally, this study investigates long-term solar modulation over millennial timescales utilizing cosmogenic 14 C isotope records and assesses radiation dose rates relevant for deep space missions, showing good agreement with Cosmic Ray Telescope for the Effects of Radiation/D1D2 measurements. This work thus provides a new framework for predicting GCR fluxes and associated radiation exposure in deep space.}, archive = {J_ApJ}, author = {Zhenning Shen and Caixia Li and Pingbing Zuo and Gang Qin and Xiaojun Xu}, doi = {10.3847/1538-4357/ade71b}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {262}, shortjournal = {The Astrophys. J.}, title = {Solar modulation of galactic cosmic rays from hydrogen to nickel based on a modified force-field approach}, volume = {988}, year = {2025}, }
• (2025). A theoretical three-dimensional diagram to separate star formation, active galactic nuclei, and shocks in galaxies. ApJ, 988(2), 261. (www)

  @article{ , abstract = {The excitation sources in galaxies are frequently mixed owing to active galactic nucleus (AGN) and stellar feedback, including star formation, AGN, and shock excitation. Disentangling the star formation, AGN, and shocks in galaxy integral field unit (IFU) spectra at optical wavelengths is crucial to expanding the galaxy sample for AGN and stellar feedback studies, given the lack of multiwavelength observations for most of the galaxies that are observed in optical wavelengths. Previous methods to address this issue either have a limited application range or are highly uncertain in separating AGN from shock excitation. Here we propose a theoretical three-dimensional (3D) diagram. This theoretical 3D diagram overcomes the limitations of previous methods and can simultaneously separate star formation, AGN, and shocks in active galaxies. Along with the separation, the new theoretical 3D diagram also constrains the gas metallicity, ionization parameter, and gas pressure within the galaxy. By applying the Very Large Telescope/MUSE IFU data and the Wide Field Spectrograph IFU data for NGC 5728 on the theoretical 3D diagram, we find a star-forming ring surrounding the galaxy center with a projected radius of ∼1 kpc in the sky plane, an AGN ionized bicone extended up to ∼2 kpc from the nuclear center, and a fast-shock-dominated disk region at the base of the AGN outflow, which is likely associated with a nuclear accretion disk or the result of jet–interstellar medium interaction. The theoretical 3D diagram opens a new window in which to study the interplay among star formation, AGN, and shocks in active galaxies.}, archive = {J_ApJ}, author = {Peixin Zhu and Lisa J. Kewley and Ralph S. Sutherland and Kathryn Grasha}, doi = {10.3847/1538-4357/ade78f}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {261}, shortjournal = {The Astrophys. J.}, title = {A theoretical three-dimensional diagram to separate star formation, active galactic nuclei, and shocks in galaxies}, volume = {988}, year = {2025}, }
• (2025). Energy budget in the 2017 september 7 “Cold” solar flare. ApJ, 988(2), 260. (www)

  @article{ , abstract = {A subclass of early impulsive solar flares, cold flares, was proposed to represent a clean case, where the release of the free magnetic energy (almost) entirely goes to the acceleration of the nonthermal electrons, while the observed thermal response is entirely driven by the nonthermal energy deposition to the ambient plasma. This paper studies one more example of a cold flare, which was observed by a unique combination of instruments. In particular, this is the first cold flare observed with the Expanded Owens Valley Solar Array and, thus, for which the dynamical measurement of the coronal magnetic field and other parameters at the flare site is possible. With these new data, we quantified the coronal magnetic field at the flare site but did not find statistically significant variations of the magnetic field within the measurement uncertainties. We estimated that the uncertainty in the corresponding magnetic energy exceeds the thermal and nonthermal energies by an order of magnitude; thus, there should be sufficient free energy to drive the flare. We discovered a very prominent soft-hard-soft spectral evolution of the microwave-producing nonthermal electrons. We computed energy partitions and concluded that the nonthermal energy deposition is likely sufficient to drive the flare thermal response similarly to other cold flares.}, archive = {J_ApJ}, author = {Gregory D. Fleishman and Galina G. Motorina and Sijie Yu and Gelu M. Nita}, doi = {10.3847/1538-4357/ade983}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {260}, shortjournal = {The Astrophys. J.}, title = {Energy budget in the 2017 september 7 “Cold” solar flare}, volume = {988}, year = {2025}, }
• (2025). Low-mass eclipsing binaries KIC 4908495, KIC 6466939, and KIC 9474485: Isolated pre-main-sequence systems?. ApJ, 988(2), 259. (www)

  @article{ , abstract = {We present a detailed analysis of three Kepler eclipsing binaries, KIC 4908495, KIC 6466939, and KIC 9474485. Our analysis reveals that these systems are composed of components possessing a lower mass than our Sun with slight subsolar metallicities. Individual analysis of the evolutionary status of each system interestingly suggests that all component stars in all three systems are pre-main-sequence (PMS) stars that have already developed a radiative core and are on the way to the zero-age main sequence in the Hertzsprung–Russell diagram. Estimated ages are 25 ± 5, 22 ± 6 and 25 ± 15 Myr for KIC 4908495, KIC 6466939 and KIC 9474485, respectively. However, none of these systems is a cluster or association member, indicating that the targets might be isolated eclipsing binaries possessing PMS components. Kepler light curves show noticeable wave-like variability at out-of-eclipse parts, suggesting a considerable magnetic activity manifesting as the rotational modulation of cool surface spots or spot groups. Projected rotational velocities of the components and amplitude spectrum of out-of-eclipse variability suggest either asynchronous rotation of the component stars or the surface differential rotation of the magnetically active component.}, archive = {J_ApJ}, author = {Orkun Özdarcan}, doi = {10.3847/1538-4357/ade986}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {259}, shortjournal = {The Astrophys. J.}, title = {Low-mass eclipsing binaries KIC 4908495, KIC 6466939, and KIC 9474485: Isolated pre-main-sequence systems?}, volume = {988}, year = {2025}, }
• (2025). Probing the internal structure of neutron stars: A comparative analysis of three different classes of equations of state. ApJ, 988(2), 258. (www)

  @article{ , abstract = {Sound speed can be an important tool in unravelling the nature of matter at the cores of neutron stars. In this study, we investigate three major classes of equations of state: monotonic, nonmonotonic, and discontinuous, depending on the nature of the sound speed in neutron stars. The monotonic equation of state refers to hadronic models, the nonmonotonic refers to the quarkyonic or smooth crossover models, and discontinuous refers to the first-order phase transition models. We generate a large ensemble of equations of state for three classes with the model-agnostic speed of sound interpolation approach. Further, we find the Bayesian posterior distribution employing the recent astrophysical and gravitational wave constraints. Our main aim is to identify which class of equation of state is most favored by present astrophysical and gravitational wave bounds. The analysis with posterior distribution fails to provide a satisfactory result with the usual neutron star observations like mass–radius and f -mode oscillations. Universal relations are seen as not being really universal, as they show considerable spread and significant overlaps among the different classes. The Bayesian evidence also fails to provide definitive discrimination between the models, though the astrophysical data slightly favors the nonmonotonic equation of state, while the particular gravitational-wave constraints favor the monotonic one.}, archive = {J_ApJ}, author = {Anshuman Verma and Asim Kumar Saha and Tuhin Malik and Ritam Mallick}, doi = {10.3847/1538-4357/ade9a2}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {258}, shortjournal = {The Astrophys. J.}, title = {Probing the internal structure of neutron stars: A comparative analysis of three different classes of equations of state}, volume = {988}, year = {2025}, }
• (2025). Magnetic activities of wolf 359: Starspot distribution and quasiperiodic pulsation using TESS data. ApJ, 988(2), 257. (www)

  @article{ , abstract = {Wolf 359 is the fifth closest (∼2.4 pc) star to Earth and a candidate exoplanet-hosting M6 dwarf. We studied the distribution of starspots and flaring activities of Wolf 359 to understand its stellar atmosphere and magnetic activities. Using 2 minute short-cadence Transiting Exoplanet Survey Satellite (TESS) data on this highly active star, we found 48, 46, and 32 flares in Sectors 45, 46, and 72, respectively. The rotation period from TESS is estimated to be 2.69 days with negligible error, which matches well with the previous literature values. We estimated the bolometric flare energy in the range of 10 30 –10 32 erg, including a high flare event of 4.2 ± 0.5 × 10 32 erg with a duration of 244.8 minutes. A high magnetic field strength of 0.18 kG is required to produce such a high flare. Interestingly, we first detect two complex flare events with oscillation periods of 104.56 ± 0.59 minutes and 39.22 ± 0.42 minutes in Sectors 45 and 46, probably caused by periodic motions of the emitting plasma or oscillatory reconnection. We estimated the mean spot temperature to be 2772 ± 100 K and the spot area to be 1.30% of the area of the star. We also correlate the duration of a flare event with its energy, \bigtriangleup t\propto {E}_{\mathrm{bol}}^{0.55\pm 0.01} , and this steeper slope likely reflects differences in magnetic field topology, atmospheric cooling behavior, and possibly multi-loop flare complexity compared to other M dwarfs. We noticed the deviation in flare rate distribution and orbital phases, indicating the presence of highly active regions, or it might be a star–planet interaction.}, archive = {J_ApJ}, author = {Diya Ram and Soumen Mondal and Samrat Ghosh and Rajib Kumbhakar}, doi = {10.3847/1538-4357/ade9a7}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {257}, shortjournal = {The Astrophys. J.}, title = {Magnetic activities of wolf 359: Starspot distribution and quasiperiodic pulsation using TESS data}, volume = {988}, year = {2025}, }
• (2025). Cosmic-ray propagation in young embedded clusters. ApJ, 988(2), 256. (www)

  @article{ , abstract = {This paper constructs a quantitative description for the geometrical properties of young stellar clusters using a Delaunay mesh. This approach defines the paths that connect cluster members and can be used to characterize the distribution of path lengths and other geometrical properties of these systems. As an application, we use this characterization to study the propagation of cosmic rays through the cluster, and estimate the resulting enhancement of cosmic-ray energy density. In the limit where magnetic fields are strong enough to confine cosmic rays, the magnetic field lines provide paths between neighboring stellar members, so that particles must travel along the paths defined by the Delaunay mesh. As a result, cosmic rays, which are locally accelerated by young stellar objects in the cluster, must random walk through the mesh in order to escape. For young stellar clusters with the properties found in the solar neighborhood, we find that once the gas has been dispersed (so that particle attenuation is insignificant), the increased escape time due to the random walk enhances the energy density in cosmic rays by a factor of ∼100 over the background on size scales of circumstellar disks.}, archive = {J_ApJ}, author = {Marco Fatuzzo and Fred C. Adams}, doi = {10.3847/1538-4357/adea49}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {256}, shortjournal = {The Astrophys. J.}, title = {Cosmic-ray propagation in young embedded clusters}, volume = {988}, year = {2025}, }
• (2025). Acceleration and transport of the unstable cosmic-ray isotope 60Fe in supernova-enriched environments. ApJ, 988(2), 255. (www)

  @article{ , abstract = {The unstable isotope 60 Fe, with a half-life of 2.6 million years, is produced primarily in supernova explosions. The observed presence of 60 Fe in cosmic rays and its detection in deep-sea crusts and sediments suggest two possible scenarios: either the direct acceleration of 60 Fe from supernova ejecta or its enrichment in the circumstellar material surrounding supernova progenitors, which indicates cosmic ray production in clusters of supernovae. Focusing on the latter scenario, we consider an environment shaped by successive supernova explosions, reminiscent of the Local Bubble around the time of the most recent supernova explosion. We independently tracked the evolution of the 60 Fe mass ratio within the Local Bubble using passive scalars. To investigate the spectra of protons and 60 Fe, we explicitly modeled cosmic-ray acceleration and transport at the remnant of the last supernova by simultaneously solving the hydrodynamical equations for the supernova outflow and the transport equations for cosmic rays, scattering turbulence, and large-scale magnetic field, using the time-dependent acceleration code Radiation Acceleration Transport Parallel Code. The main uncertainty in our prediction of the local 60 Fe flux at about pc = 1 GeV nuc −1 is the magnetic-field structure in the Local Bubble and the cosmic-ray diffusion beyond the approximately 100 kyr of evolution covered by our study. We found that if the standard galactic propagation applies, the local 60 Fe flux would be around 3% of that measured. If there is a sustained reduction in the diffusion coefficient at and near the Local Bubble, then the expected 60 Fe flux could be up to 30% of that measured.}, archive = {J_ApJ}, author = {Xin-Yue Shi and Martin Pohl and Michael M. Schulreich}, doi = {10.3847/1538-4357/adea4c}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {255}, shortjournal = {The Astrophys. J.}, title = {Acceleration and transport of the unstable cosmic-ray isotope 60Fe in supernova-enriched environments}, volume = {988}, year = {2025}, }
• (2025). Formation of the two-armed phase spiral from multiple external perturbations. ApJ, 988(2), 254. (www)

  @article{ , abstract = {Recent studies using the Gaia DR3 data have revealed a two-armed phase spiral in the Z – V Z phase space in the inner disk. In this study, we present new features of the two-armed phase spiral revealed by the Gaia data and a new mechanism to explain such features with multiple external perturbations. By segmenting the Gaia DR3 Radial Velocity Spectrometer (RVS) catalog based on J ϕ (or R g ) and θ ϕ , we confirm the existence of a clear two-armed phase spiral in the inner disk. Moreover, we identify a different two-armed phase spiral pattern at slightly larger radii, resembling a weak secondary branch along with the prominent major branch. At a given radius, with the azimuthal angle increasing, we observe a systematic transition of the two-armed phase spiral, with the significance of one branch weakened and another branch enhanced. This two-armed phase spiral may be due to the overlapping of distinct one-armed phase spirals. At different radii, the perturbation times estimated from each branch of the two-armed phase spiral are ∼320 and ∼500 Myr, respectively, suggesting that the Galactic disk could be impacted by double external perturbers separated by ∼180 Myr. We also performed test-particle simulations of the disk perturbed by two satellite galaxies, which successfully generated a two-armed phase spiral similar to the observation. Both the observation and simulation results suggest that the signature in the Z – V Z phase space of earlier perturbations may not be completely erased by the more recent one.}, archive = {J_ApJ}, author = {Junxian Lin and Zhao-Yu Li and Rui Guo and Jason A. S. Hunt and T. Antoja and Chengye Cao}, doi = {10.3847/1538-4357/adea70}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {254}, shortjournal = {The Astrophys. J.}, title = {Formation of the two-armed phase spiral from multiple external perturbations}, volume = {988}, year = {2025}, }
• (2025). Polytropic analysis of large-scale compressive fluctuations in the solar wind: Fluid and kinetic behavior. ApJ, 988(2), 253. (www)

  @article{ , abstract = {Large-scale compressive plasma fluctuations in the solar wind are typically characterized by an anticorrelation between the plasma density and the magnitude of the magnetic field, and thus share polarization properties with slow waves. The nature of the slow modes in the solar wind with respect to the polarization properties of the plasma has been found to be in better agreement with the magnetohydrodynamic (MHD) slow mode predictions compared to that of the kinetic slow mode. The polytropic behavior of the plasma in compressive fluctuations may provide further insight into the nature of the slow mode, since the MHD, Chew–Goldberger–Low (CGL), and kinetic slow modes predict different proton polytropic indices ( γ ). Using Solar Orbiter observations, we identify two 1–2 hr intervals of compressive fluctuations with a low probability of streamline crossings, determine the effective polytropic index of protons and electrons for both events, and compare them with the theoretical expectations of MHD, CGL, and kinetic slow modes. One interval exhibits characteristics of the MHD slow mode having a clear isotropic closure for the protons with γ p ≈ 1.7, while the other interval is more consistent with the kinetic slow mode. The calculated electron polytropic index is γ e ≈ 0.7 for both events. We decompose the signals into three different frequency bands and repeat our analysis, finding a similar difference in the proton polytropic behavior between the two events. A scale dependence is also observed, suggesting that kinetic effects become more prominent at smaller scales.}, archive = {J_ApJ}, author = {C. Ioannou and G. Nicolaou and C. J. Owen and D. Verscharen and J. T. Coburn and L. Franci}, doi = {10.3847/1538-4357/adeb7b}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {253}, shortjournal = {The Astrophys. J.}, title = {Polytropic analysis of large-scale compressive fluctuations in the solar wind: Fluid and kinetic behavior}, volume = {988}, year = {2025}, }
• (2025). SOFIA/HAWC+ far-infrared polarimetric large area CMZ exploration survey. v. the magnetic field strength and morphology in the sagittarius c complex. ApJ, 988(2), 252. (www)

  @article{ , abstract = {We present an analysis of the magnetic field strength and morphology in the Sagittarius C complex (Sgr C; G359.43-0.09) in the Milky Way’s Central Molecular Zone (CMZ), using the 214 μ m polarimetry data acquired with the High-resolution Airborne Wide-band Camera instrument on board the Stratospheric Observatory for Infrared Astronomy. We conduct a modified Davis–Chandrasekhar–Fermi analysis of individual clouds and find that the sky-plane magnetic field strength varies from highly turbulent regions having inferred strengths of ∼30 μ G to regions of relatively uniform field orientation having strengths of ∼400 μ G. Several hundred magnetic field pseudovectors in the Sgr C region were measured to trace the projected magnetic field orientation within cold molecular clouds, and as is the trend throughout the CMZ, they show a higher polarization fraction toward the periphery of the clouds. The magnetic field orientations suggest that outflows from active star-forming regions, such as the G359.43-0.10 extended green object and the protostellar source FIR-4 (G359.43+0.02), cause high turbulence in their vicinity. The magnetic field direction is found to be tangential to the surface of the Sgr C H II region, which displays spatial correspondence with two [C II ] emission cavities reported in the H II region, signifying a compression front between the H II region and the surrounding dense clouds. Several other features in the vicinity of Sgr C, especially numerous nonthermal radio filaments and a diffuse source of X-ray emission to the immediate southwest of the H II region, are discussed with regard to the magnetic field measurements.}, archive = {J_ApJ}, author = {Roy J. Zhao and Mark R. Morris and David T. Chuss and Dylan M. Paré and Jordan A. Guerra and Natalie O. Butterfield and Edward J. Wollack and Kaitlyn Karpovich}, doi = {10.3847/1538-4357/ade80d}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {252}, shortjournal = {The Astrophys. J.}, title = {SOFIA/HAWC+ far-infrared polarimetric large area CMZ exploration survey. v. the magnetic field strength and morphology in the sagittarius c complex}, volume = {988}, year = {2025}, }
• (2025). Dust in the smith cloud? a UV investigation into the smith cloud’s gas-phase abundance patterns. ApJ, 988(2), 251. (www)

  @article{ , abstract = {The Smith Cloud is a high-velocity cloud (HVC) on its final approach to the Milky Way that shows evidence of interaction with the Galaxy’s disk. We investigate the metallicity and gas-phase chemical depletion patterns in this HVC using UV absorption-line observations toward two background QSOs taken with the Hubble Space Telescope/Cosmic Origin Spectrograph and H i 21 cm emission-line observations taken with Green Bank Telescope. We find evidence of silicon gas-phase depletion with [Si/S] = -0.7{2}_{-0.26}^{+0.24} and [Si/O] 3 σ ≲ −0.05, implying the presence of dust within the Smith Cloud. Because dust is galactic in origin, this HVC could trace the return leg of a Galactic fountain or a dwarf galaxy that passed through the Galactic plane.}, archive = {J_ApJ}, author = {Johanna T. Vázquez and Kathleen A. Barger and Frances H. Cashman and Andrew J. Fox and Bart P. Wakker and Felix J. Lockman and Alex S. Hill and Suraj Poudel and April L. Horton and Jaq Hernández and Matthew Nuss and Alice Blake and Lauren Corlies and Molly Peeples}, doi = {10.3847/1538-4357/add2ee}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {251}, shortjournal = {The Astrophys. J.}, title = {Dust in the smith cloud? a UV investigation into the smith cloud’s gas-phase abundance patterns}, volume = {988}, year = {2025}, }
• (2025). Figuring out gas and galaxies in enzo (FOGGIE). IX. the angular momentum evolution of milky way–like galaxies and their circumgalactic gas. ApJ, 988(2), 250. (www)

  @article{ , abstract = {We investigate the coevolution of the angular momentum of Milky Way–like galaxies, their circumgalactic gas, and their dark matter halos using zoom-in simulations from the Figuring Out Gas and Galaxies in Enzo suite. We examine how the magnitude and orientation of the angular momentum vary over time within the halo and between the components of mass. From z ∼ 2 to today, and in general across the simulated halos, the specific angular momenta of the central galaxies and the cool gas in their circumgalactic media ( T < 10 5 K) increase together. Over that same period, the specific angular momenta of the hot (>10 6 K) and dark components of the halo change minimally. By z ∼ 1, the central galaxies have generally lost association with the angular momentum of their full dark matter halo, both in magnitude and orientation. We find a wide distribution of angular momentum orientations in the halo, varying by up to 180° over small (∼tens of kiloparsecs) scales and between the different components of mass. The net angular momenta of the galaxies, their circumgalactic gas, and their dark matter halos are generally misaligned with one another at all cosmic times. The present-day orientation of the central galaxies is established at late times (after z = 1), after the rates of cosmic accretion and mergers decline and the disks are able to settle and stabilize their orientation.}, archive = {J_ApJ}, author = {Raymond C. Simons and Molly S. Peeples and Jason Tumlinson and Brian W. O’Shea and Cassandra Lochhaas and Anna C. Wright and Ayan Acharyya and Ramona Augustin and Kathleen A. Hamilton-Campos and Britton D. Smith and Nicolas Lehner and Jessica K. Werk and Yong Zheng}, doi = {10.3847/1538-4357/addf39}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {250}, shortjournal = {The Astrophys. J.}, title = {Figuring out gas and galaxies in enzo (FOGGIE). IX. the angular momentum evolution of milky way–like galaxies and their circumgalactic gas}, volume = {988}, year = {2025}, }
• (2025). Truncations in the X-ray halos of early-type galaxies as a tracer of feedback and mergers. ApJ, 988(2), 249. (www)

  @article{ , abstract = {The morphology of X-ray halos in early-type galaxies depends on key structure assembly processes, such as feedback and mergers. However, the signatures of these processes are difficult to characterize due to their faint and amorphous nature. We demonstrate that the truncation in the temperature profile of X-ray halos, defined by the radial location of the peak temperature, is significantly more impacted by recent mergers or galaxy interactions than feedback processes. At a fixed stellar mass, a highly asymmetric X-ray halo can be nearly a factor of 10 more truncated than a relaxed one. This analysis led to a discovery of previously unknown asymmetric features in the optical and X-ray halos of three massive galaxies. We detect the intra-group star light and a large ∼45 kpc size stellar stream connected to NGC 0383, suggesting that a recent stellar accretion event has triggered its active galactic nuclei to emit a powerful radio jet. While the disturbed X-ray halo of NGC 1600 is also related to a galaxy-satellite tidal interaction detected in optical imaging, the X-ray shape and asymmetry of NGC 4555 are highly unusual for a galaxy in a low-density environment, requiring further investigation. These results highlight the importance of truncations and deep imaging techniques for untangling the formation of X-ray halos in massive galaxies.}, archive = {J_ApJ}, author = {Nushkia Chamba and Pamela M. Marcum and Alejandro S. Borlaff and Pasquale Temi and Aneta Siemiginowska}, doi = {10.3847/1538-4357/ade873}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {249}, shortjournal = {The Astrophys. J.}, title = {Truncations in the X-ray halos of early-type galaxies as a tracer of feedback and mergers}, volume = {988}, year = {2025}, }
• (2025). The coupling and evolution of Kelvin–Helmholtz and Rayleigh–Taylor instabilities in the heliosheath. ApJ, 988(2), 248. (www)

  @article{ , abstract = {The shape and structure of the heliosphere remain subjects of ongoing debate, with current models differing on how far the heliospheric jets that form the two-lobe structure extend down the heliotail and whether the surrounding interstellar medium can penetrate the region between the lobes. Rayleigh–Taylor (RT) and Kelvin–Helmholtz (KH) instabilities along the axis of the heliospheric jets have been proposed as key drivers of turbulence in the heliosheath (HS). In this work, we present results from 225 yr MHD simulations that reveal periodic variations in solar wind speed and magnetic field within the HS, coinciding with the cyclic growth of RT and KH instabilities. At the onset of each cycle, the instabilities initially develop simultaneously in the direction normal to the plane of the heliospheric jet, with an average timescale of ∼4.2 yr. As the system evolves over ∼11.1 yr, RT and KH modes decouple, with KH modes subsequently dominating beyond the high-density region and leading to a reduced growth rate, corresponding to a timescale of ∼12.9 yr. These findings suggest that RT and KH instabilities can coevolve and reoccur periodically, contributing to turbulence generation in the HS. Their nonlinear development may play a fundamental role in shaping the large-scale structure of the heliosphere, particularly in the formation and evolution of the open heliospheric tail.}, archive = {J_ApJ}, author = {Xiaohan Ma and Merav Opher and Marc Kornbleuth}, doi = {10.3847/1538-4357/ade881}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {248}, shortjournal = {The Astrophys. J.}, title = {The coupling and evolution of Kelvin–Helmholtz and Rayleigh–Taylor instabilities in the heliosheath}, volume = {988}, year = {2025}, }
• (2025). Tidal inflation is stronger for misaligned neptune-sized planets than aligned ones. ApJ, 988(2), 247. (www)

  @article{ , abstract = {Recent observations have revealed an intriguing abundance of polar-orbiting Neptune-sized planets, many of which exhibit unusually inflated radii. While such misaligned orbits point to a complex dynamical history, the connection between their orbital orientations and planetary structures remains poorly understood. In this study, we analyze a sample of 12 misaligned and 12 aligned planets using structure models that incorporate tidal heating. We use various statistical tests to demonstrate—with at least 90% confidence—that misaligned planets experience more tidally induced radius inflation compared to aligned planets. This inflation likely stems from their dynamically active histories, which often place them in close-in, eccentric, and highly inclined orbits. We further present a case study of WASP-107 b, an exceptionally inflated polar Neptune, and model its history using a simple coupled orbital and radius evolution approach. Our results place constraints on the planet’s tidal quality factor that agree with recent JWST observations.}, archive = {J_ApJ}, author = {Ritika Sethi and Sarah C. Millholland}, doi = {10.3847/1538-4357/ade883}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {247}, shortjournal = {The Astrophys. J.}, title = {Tidal inflation is stronger for misaligned neptune-sized planets than aligned ones}, volume = {988}, year = {2025}, }
• (2025). Environmental evidence for overly massive black holes in low-mass galaxies and a black Hole–Halo mass relation at z ∼ 5. ApJ, 988(2), 246. (www)

  @article{ , abstract = {JWST observations have unveiled faint active galactic nuclei (AGNs) at high redshift that provide insights into the formation of supermassive black holes (SMBHs). However, disentangling their stellar from AGN light is challenging. Here, we use an empirical approach to infer the average stellar mass of five faint broad-line (BL) H α emitters at z = 4–5 with BH masses ≈6 × 10 6 M ⊙ , with a method independent of their spectral energy distribution (SED). We use the deep JWST/NIRcam grism survey “All the Little Things” to measure the overdensities around BL-H α emitters and around a spectroscopic reference sample of ∼300 galaxies. In our reference sample, we find that megaparsec-scale overdensity correlates with stellar mass. Their large-scale environments suggest that BL-H α emitters are hosted by galaxies with stellar masses ≈5 × 10 7 M ⊙ , ≈40 times lower than those inferred from galaxy-only SED fits. Adding measurements around more luminous z ≈ 6 AGNs, we find tentative correlations between line width, BH mass, and the overdensity, suggestive of a steep BH to halo mass relation. The main implications are (1) when BH masses are taken at face value, we confirm extremely high BH to stellar mass ratios of ≈10%, (2) the galaxies of low stellar mass that host growing SMBHs are in tension with typical hydrodynamical simulations, except those without feedback, (3) a 1% duty cycle implied by the host mass hints at super-Eddington accretion, (4) the masses are at odds with an interpretation of the line broadening in terms of high stellar density, (5) our results imply a luminosity-dependent diversity of galaxy masses, environments, and SEDs among AGN samples.}, archive = {J_ApJ}, author = {Jorryt Matthee and Rohan P. Naidu and Gauri Kotiwale and Lukas J. Furtak and Ivan Kramarenko and Ruari Mackenzie and Jenny Greene and Angela Adamo and Rychard J. Bouwens and Claudia Di Cesare and Anna-Christina Eilers and Anna de Graaff and Kasper E. Heintz and Daichi Kashino and Michael V. Maseda and Sandro Tacchella and Alberto Torralba}, doi = {10.3847/1538-4357/ade886}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {246}, shortjournal = {The Astrophys. J.}, title = {Environmental evidence for overly massive black holes in low-mass galaxies and a black Hole–Halo mass relation at z ∼ 5}, volume = {988}, year = {2025}, }
• (2025). Synchrotron-limited particle acceleration in relativistic shearing flows. ApJ, 988(2), 245. (www)

  @article{ , abstract = {Fermi-type shear particle acceleration is a promising mechanism for sustaining ultrarelativistic particles along the kiloparsec scale jets in active galactic nuclei. We explore the possibility of synchrotron-limited electron acceleration in mildly relativistic shearing flows and present numerical solutions to the corresponding particle transport equation. We compare our findings with analytical calculations to infer an effective electron cutoff energy, and discuss the relationship to a simplified box model treatment. The results show that mildly relativistic large-scale jets offer a suitable environment for distributed electron acceleration beyond Lorentz factors of γ e ∼ 10 8 .}, archive = {J_ApJ}, author = {Frank M. Rieger and Peter Duffy}, doi = {10.3847/1538-4357/adec67}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {245}, shortjournal = {The Astrophys. J.}, title = {Synchrotron-limited particle acceleration in relativistic shearing flows}, volume = {988}, year = {2025}, }
• (2025). NuSTAR analysis of the 2024 periastron passage of TeV binary PSR b1259-63. ApJ, 988(2), 244. (www)

  @article{ , abstract = {PSR B1259-63 is a well-studied TeV binary, with an energetic pulsar in orbit around a Be star. Using Nuclear Spectroscopic Telescope Array observations during the 2024 passage of the pulsar through the circumstellar disk, we find the spectrum to be the most energetic (Γ = 1.5) around 27 days after periastron, during the first of two variable, short-term emission episodes of a contemporaneous GeV flare. We discuss the variability in the X-ray flux and the hardening of the spectrum with time, and in the context of previous observations and what that means for the competing energy loss and acceleration timescales.}, archive = {J_ApJ}, author = {Oliver J. Roberts and Philip Kaaret and M. Lynne Saade and Chien-Ting Chen and Steven R. Ehlert and Ioannis Liodakis and Martin C. Weisskopf}, doi = {10.3847/1538-4357/adec6a}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {244}, shortjournal = {The Astrophys. J.}, title = {NuSTAR analysis of the 2024 periastron passage of TeV binary PSR b1259-63}, volume = {988}, year = {2025}, }
• (2025). Dynamical dark energy in the crosshairs: A joint analysis with DESI, type ia supernovae, and TDCOSMO constraints. ApJ, 988(2), 243. (www)

  @article{ , abstract = {In this work, we perform a comprehensive joint analysis of three representative dark energy models—ΛCDM, the Chevallier–Polarski–Linder (CPL) parameterization, and the Generalized Emergent Dark Energy (GEDE) model—using the latest observational data sets: baryon acoustic oscillation measurements from Dark Energy Spectroscopic Instrument (DESI) Data Release 1 (DR1) and 2 (DR2), Type Ia supernovae, and time-delay cosmography from Time-Delay COSMOgraphy (TDCOSMO) lensing. The CPL model yields a statistically significant improvement over ΛCDM, with ΔAIC = −0.54 for DESI DR2+Dark Energy Survey Y5+TDCOSMO, favoring a quintessence-like behavior ( {w}_{0}=-0.8{2}_{-0.05}^{+0.05} , {w}_{a}=-0.4{3}_{-0.31}^{+0.32} at 1 σ confidence level). The GEDE model also exhibits slightly favoring than ΛCDM with observations, yielding ΔAIC = −2.15. The captured potential dark energy evolution transition parameter Δ in GEDE model is constrained to -0.5{2}_{-0.20}^{+0.22} (DR1) and -0.5{0}_{-0.17}^{+0.18} (DR2), showing a 2.4 σ and 2.9 σ deviation from zero, respectively. This more than 2 σ statistically significant of nonzero value of Δ provides evidence against a pure cosmological constant scenario. The negative sign indicates quintessence-like behavior ( w > −1) in the late universe. Notably, the GEDE constraints show a more than 3 σ tension with the Δ = 1 (Phenomenological Emergent Dark Energy model) predictions. This significant discrepancy implies that while both models belong to the emergent dark energy family, their fundamentally different transition mechanisms lead to distinct cosmological implications. Our results collectively suggest that GEDE provides a phenomenologically viable alternative to ΛCDM.}, archive = {J_ApJ}, author = {Tonghua Liu and Xiaolei Li and Jieci Wang}, doi = {10.3847/1538-4357/aded8b}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {243}, shortjournal = {The Astrophys. J.}, title = {Dynamical dark energy in the crosshairs: A joint analysis with DESI, type ia supernovae, and TDCOSMO constraints}, volume = {988}, year = {2025}, }
• (2025). Magnetic field variability as a consistent predictor of solar flares. ApJ, 988(2), 242. (www)

  @article{ , abstract = {Solar flares are intense bursts of electromagnetic radiation that occur due to a rapid destabilization and reconnection of the magnetic field. While preflare signatures and trends have been investigated from magnetic observations prior to flares for decades, analysis that characterizes the variability of the magnetic field in the hours prior to flare onset has not been included in the literature. Here, the 3D magnetic field is modeled using a nonlinear force-free field extrapolation for 6 hr before and 1 hr after 18 on-disk solar flares and flare quiet windows for each active region. Parameters are calculated directly from the magnetic field from two field isolation methods: the “active region field,” which isolates field lines where the photospheric field magnitude is ≥200 Gauss, and the “high current region,” which isolates field lines in the 3D field where the current, nonpotential field, twist, and shear exceed predefined thresholds. For this small pool of clean events, there is a significant increase in variation starting 2–4 hr before flare onset for the current, twist, shear, and free energy, and the variation continues to increase through the flare start time. The current, twist, shear, and free energy are also significantly stronger through the lower corona and their separation from flare quiet height curves scales with flare strength. Methods are proposed to combine variation of the magnetic fields with variation of other data products prior to flare onset, suggesting a new potential flare prediction capability.}, archive = {J_ApJ}, author = {K. L. Kniezewski and E. I. Mason and D. J. Emmons and K. E. Fitch and S. H. Garland}, doi = {10.3847/1538-4357/ade5ae}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {242}, shortjournal = {The Astrophys. J.}, title = {Magnetic field variability as a consistent predictor of solar flares}, volume = {988}, year = {2025}, }
• (2025). The mass of the vela pulsar progenitor and the age of the vela-puppis complex. ApJ, 988(2), 241. (www)

  @article{ , abstract = {The association of the Vela Pulsar with the Vela Supernova Remnant has long supported the hypothesis that core-collapse supernovae yield neutron stars, but its surrounding stellar population now offers new insights into progenitor evolution. By age-dating stars within 150 pc of the Vela Pulsar, we infer properties of its progenitor. These stars belong to the Vela-Puppis complex, revealing the region’s star formation history. While stellar population models with standard assumptions suggest a likely progenitor age and mass, these predictions are internally inconsistent with the observed population, indicating that something is missing in the standard modeling approach. With those assumptions, there is very weak support for a ≲10 Myr old population, moderate support for a 40 Myr old population, and strong support for an intermediate-age population around 65–100 Myr old. The ≲10 Myr signal hinges on two peculiar O stars, which are unlike any others in the Vela-Puppis complex and imply nearly three times more main-sequence (MS) stars than are observed. The 40 Myr old population is supported by six red supergiants and several Be stars, but this population is again marginally inconsistent with the observed distribution of MS stars. The red giant and MS distributions are consistent with a 65–100 Myr old population. We discuss several possible resolutions, emphasizing how binary evolution and/or very rapid rotation could resolve these discrepancies. Gaia parallaxes and Stellar Ages enable these results; Stellar Ages is a novel stellar population modeling algorithm that combines individual and population-level age inferences.}, archive = {J_ApJ}, author = {Jeremiah W. Murphy and Andrés F. Barrientos and René Andrae and Joseph Guzman and Benjamin F. Williams and Julianne J. Dalcanton and Brad Koplitz}, doi = {10.3847/1538-4357/ade5b4}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {241}, shortjournal = {The Astrophys. J.}, title = {The mass of the vela pulsar progenitor and the age of the vela-puppis complex}, volume = {988}, year = {2025}, }
• (2025). Investigating the physical properties of dusty star-forming galaxies at z ≳ 1.5 in the GOODS-south field using JWST. ApJ, 988(2), 240. (www)

  @article{ , abstract = {We investigated how well the physical properties of progenitors of present-day massive spheroidal galaxies (protospheroids) can be constrained by the JWST Advanced Deep Extragalactic Survey (JADES) in the GOODS-South field, which benefits from extensive photometric and spectroscopic data, including those from the Hubble, Spitzer, and Herschel. We adopted a physical model for the evolution of protospheroidal galaxies, which form the bulk of dusty star-forming galaxies (DSFGs) at z ≳ 1.5 and confirmed its consistency with recent mid-infrared high- z galaxy luminosity functions. Using the model and the JADES survey strategy, we simulated a sample of protospheroids over 87.5 arcmin 2 , matching the JADES/GOODS-S survey area. Photometric redshifts estimated from simulated JWST photometry showed ≳95% accuracy and were used in spectral energy distribution fittings with Code Investigating GALaxy Emission (CIGALE). We demonstrated that JWST will provide reliable stellar mass estimates up to 0.1 dex for the majority of protospheroids at z ≳ 1.5 and can detect low-mass systems during cosmic noon that were inaccessible in the pre-JWST era. Focusing on the active star-forming phase of the protospheroid evolution, we defined a subsample flux limited at 250 μ m (DSFG sample) and derived star formation rate, dust luminosity, and dust mass complementing the JWST photometry with that from Spitzer/MIPS and Herschel. We also constructed a JWST-selected DSFG catalog from ASTRODEEP data using NIRCam color criteria and demonstrated strong consistency between the observed and simulated DSFG populations.}, archive = {J_ApJ}, author = {Dipanjan Mitra and Mattia Negrello and Gianfranco De Zotti}, doi = {10.3847/1538-4357/ade2e4}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {240}, shortjournal = {The Astrophys. J.}, title = {Investigating the physical properties of dusty star-forming galaxies at z ≳ 1.5 in the GOODS-south field using JWST}, volume = {988}, year = {2025}, }
• (2025). What causes errors in Wang–Sheeley–Arge solar wind modeling at l1?. ApJ, 988(2), 239. (www)

  @article{ , abstract = {Previous ambient solar wind (SW) validation studies have reported on discrepancies between modeled and observed SW conditions at L1. They indicated that a major source of discrepancies stems from how we model the solar corona. Thus, enhancing predictive capabilities demands a thorough examination of coronal modeling. The Wang–Sheeley–Arge (WSA) model has been a workhorse model that provides the near-Sun SW conditions. An important component of it is the potential field source surface model. This study analyzes 15 different Carrington rotations (CRs), and presents a detailed analysis of CR 2052 to identify WSA model settings that lead to successful and erroneous SW predictions at Earth. For the events studied, we show that increasing the model’s grid resolution improves the open–close boundary identification. This results in better predicting the onset and duration of high-speed streams (HSSs). In addition, we find an optimized source surface height ( R ss ) (lying between 1.8 and 3.1 R ⊙ ) further enhances HSS prediction accuracy for the studied events. A detailed analysis shows that changes in R ss (a) change the great circle angular distance maps (at the solar surface) of the associated coronal holes and (b) change the foot-point locations of the magnetic connectivities to the sub-Earth locations. These factors change the near-Sun SW speed, which eventually leads to uncertainties in speeds near Earth. We also investigate the usefulness of coronal hole observations in constraining R ss and SW solutions at Earth, and highlight their underutilized value in guiding the selection of magnetic maps for improved ambient solar wind modeling at L1.}, archive = {J_ApJ}, author = {Satabdwa Majumdar and Martin A. Reiss and Karin Muglach and Charles N. Arge}, doi = {10.3847/1538-4357/ade3d5}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {239}, shortjournal = {The Astrophys. J.}, title = {What causes errors in Wang–Sheeley–Arge solar wind modeling at l1?}, volume = {988}, year = {2025}, }
• (2025). Unified weak lensing constraints on the evolution of the Mass–X-ray luminosity relation for galaxy clusters. ApJ, 988(2), 238. (www)

  @article{ , abstract = {Scaling relations between galaxy cluster properties are crucial for understanding cosmology and baryonic physics. Rigorous calibration of the M – L X relation, employing weak lensing mass and consistent statistical methodology, is challenging due to heterogeneous cluster samples. The release of LEGACY imaging data introduced the possibility of unifying the cluster selection. We present the all-sky extension of the CODEX catalog based on LEGACY data and introduce a Bayesian framework for calibrating the X-ray luminosity–mass relation, derived for 100 clusters with weak lensing mass measurements. Using the X-ray luminosity estimates for those clusters from ROSAT All-Sky Survey (RASS) data, we perform a power-law fit to the M – L X relation. Furthermore, taking advantage of the recently released eROSITA data (eRASS1), we assess the impact of point source contamination on cluster fluxes for 42 clusters in the eRASS1 footprint. The RASS fit yields a slope of β = 0.75 ± 0.09, 1.7 σ lower than the best self-similar prediction, with marginal evidence for the redshift evolution of the normalization ( γ = 0.65 ± 0.43). As for the eRASS1 analysis, the slope is substantially steeper, β = 1.11 ± 0.15, and in further agreement with the prediction of self-similarity. No additional evolution is also seen ( γ = 0.004 ± 0.790). While our results provide the practical means for cosmological studies of both RASS and eRASS data, the link to cluster physics is much cleaner after the cluster flux contamination is reduced. We also analyzed the impact of the selection function on calibration, finding that its full modeling is essential.}, archive = {J_ApJ}, author = {I. Pederneiras and A. Finoguenov and E. Cypriano and J. Comparat and K. Kiiveri and L. van Waerbeke and R. Dupke}, doi = {10.3847/1538-4357/ade793}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {238}, shortjournal = {The Astrophys. J.}, title = {Unified weak lensing constraints on the evolution of the Mass–X-ray luminosity relation for galaxy clusters}, volume = {988}, year = {2025}, }
• (2025). Unveiling the cosmic dance of repeated nuclear transient ASASSN-14ko: Insights from multiwavelength observations. ApJ, 988(2), 237. (www)

  @article{ , abstract = {ASASSN-14ko is a periodically repeating nuclear transient. We conducted high-cadence, multiwavelength observations of this source, revealing several recurrent early bumps and rebrightenings in its UV/optical light curves. The energy released during these bumps and rebrightenings shows a diminishing trend in recent UV/optical outbursts, which we monitored through multiwavelength observations. These features can be ascribed to the interaction between stream debris and the expanded disk in the repeated partial tidal disruption event. The X-ray light curve exhibits an inverse pattern compared to the UV/optical bands, displaying sporadic outbursts. Furthermore, our observations demonstrate that the blackbody temperature and radius in each outburst increase with the UV/optical luminosity, and such evolution resembles that observed in X-ray quasiperiodic eruptions, distinguishing it from typical tidal disruption events.}, archive = {J_ApJ}, author = {Shifeng Huang and Tinggui Wang and Ning Jiang and Rong-Feng Shen and Zhaohao Chen and Yuanming Wang and Jiazheng Zhu and Yibo Wang and Yunguo Jiang and Xinwen Shu and Hucheng Ding and Xiongjun Fang and Yifan Wang and Jie Lin and Jingran Xu and Xu Chen and Zheyu Lin and Zhenfeng Sheng}, doi = {10.3847/1538-4357/ade795}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {237}, shortjournal = {The Astrophys. J.}, title = {Unveiling the cosmic dance of repeated nuclear transient ASASSN-14ko: Insights from multiwavelength observations}, volume = {988}, year = {2025}, }
• (2025). Quasiperiodic oscillations and reflection feature evolution in 4U 1630-47 observed with insight-HXMT. ApJ, 988(2), 236. (www)

  @article{ , abstract = {The Galactic black hole X-ray binary 4U 1630–47 went into a new outburst in 2021 after ∼600 days from its 2020 outburst. We perform a detailed analysis of quasiperiodic oscillations and spectral evolutions during its 2021 outburst based on Insight-HXMT observations. The main science aims to study the reflection features and evolution of this accreting black hole using the observations of detecting quasiperiodic oscillations (QPOs) and quasi-regular modulations (QRMs). The QPOs frequencies evolve from ∼1.6 to 3.6 Hz, and QRMs have low frequencies around 0.05–0.07 Hz. The reflection fraction varies during the outburst and has a positive correlation with the hardness ratio when QPOs are detected. The centroid frequency of QPOs is anticorrelated to the reflection fraction. This is consistent with the prediction of the precessing inner flow model and provides evidence for a geometrical origin of QPOs. The centroid frequency of QRMs also shows an anticorrelation to the reflection fraction, but the hardness ratio shows no relation to the reflection fraction during the period. We suggest that QRMs may have a different origin from QPOs and be caused by instabilities in the corona.}, archive = {J_ApJ}, author = {Jiashi Chen and Wei Wang}, doi = {10.3847/1538-4357/ade809}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {236}, shortjournal = {The Astrophys. J.}, title = {Quasiperiodic oscillations and reflection feature evolution in 4U 1630-47 observed with insight-HXMT}, volume = {988}, year = {2025}, }
• (2025). Rubidium abundances in cool giants from high-resolution H-band spectra: A new diagnostic for galactic chemical evolution. ApJ, 988(2), 235. (www)

  @article{ , abstract = {The Galactic center and inner disk of the Milky Way contain complex stellar populations obscured by heavy dust extinction. To study their chemical composition, high-resolution near-infrared (near-IR) spectroscopy is necessary. Expanding the set of elements measurable in the near-IR, especially neutron-capture elements, improves our ability to trace nucleosynthesis and Galactic chemical evolution. This work aims to identify and characterize a spectral line suitable for determining rubidium (Rb) abundances. Rubidium is produced in roughly equal parts by the r - and s -processes. We analyze high-resolution ( R = 45,000) Immersion GRating INfrared Spectrograph (or IGRINS) near-IR spectra of 40 M giants in the solar neighborhood, most observed with Gemini South. We perform spectral synthesis of the Rb i line at 15289.48 Å, using new {\mathrm{log}}\,gf values and including an astrophysical calibration of the blending Fe i lines. The resulting [Rb/Fe] ratios are compared to other neutron-capture elements and interpreted with chemical evolution models. We demonstrate that the used Rb line is a reliable abundance indicator in M giants and the coolest K giants, but becomes too weak at higher temperatures. [Rb/Fe] shows a decreasing trend with metallicity, mirroring that of ytterbium (Yb), another mixed r -/ s -process element. Our results agree with optical studies, validating the use of this near-IR line. Comparisons with chemical evolution models confirm that both s - and r -process sources are needed to explain the Rb trend. This work adds Rb to the list of elements measurable in high-resolution H - and K -band spectra, enabling studies of one more neutron-capture element in dust-obscured regions like the Galactic center and inner disk.}, archive = {J_ApJ}, author = {Nils Ryde and Jess Kocher and Govind Nandakumar and Henrik Hartman and Marta Molero and Henrik Jönsson and Gregory Mace and Erica Sawczynec and Kyle F. Kaplan}, doi = {10.3847/1538-4357/ade87a}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {235}, shortjournal = {The Astrophys. J.}, title = {Rubidium abundances in cool giants from high-resolution H-band spectra: A new diagnostic for galactic chemical evolution}, volume = {988}, year = {2025}, }
• (2025). The evolutionary pathway of low-mass supermassive black holes at intermediate redshift: Insights from the JADES survey. ApJ, 988(2), 234. (www)

  @article{ , abstract = {Understanding the relationship between supermassive black holes (SMBHs) and their host galaxies at different redshifts is crucial for unraveling the processes of SMBH–galaxy coevolution. We present the properties of nine type 1 active galactic nuclei (AGNs) at intermediate redshift (2 < z < 4) using the JWST Advanced Deep Extragalactic Survey. All of them show the significant H α broad line and the AGN contribution in spectral energy distribution. Our sample covers SMBH masses of 10 6.1−8.2 M ⊙ and stellar masses of 10 9.3−11.0 M ⊙ , comparable to those of the AGNs observed in the local Universe. In the low-mass SMBH regime (<10 8 M ⊙ ), the black hole (BH)-to-stellar mass ratios in our sample (0.01%–0.1%) differ from those of the AGNs at z > 4 (1%–10%), suggesting that BHs and galaxies may trace different evolutionary pathways at intermediate and high redshifts. We also perform 2D image decomposition using GALFIT to constrain the bulge mass by evaluating the bulge contribution in the rest-frame near-infrared flux. We identify the AGNs with low BH-to-bulge mass ratios compared to those observed in the nearby bulge-dominant galaxies. This finding suggests the existence of a galaxy-first evolutionary path, in which bulge formation occurs before substantial gas is efficiently accreted onto the central engine.}, archive = {J_ApJ}, author = {Atsushi Hoshi and Toru Yamada}, doi = {10.3847/1538-4357/adeb6a}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {234}, shortjournal = {The Astrophys. J.}, title = {The evolutionary pathway of low-mass supermassive black holes at intermediate redshift: Insights from the JADES survey}, volume = {988}, year = {2025}, }
• (2025). Measurement of neutral atmosphere density during the years of increasing solar activity using insight-HXMT data with the earth occultation technique. ApJ, 988(2), 233. (www)

  @article{ , abstract = {The density of the Earth’s middle and upper atmosphere is an important parameter in Earth science and plays a critical role in the design, operation, and orbital determination of low Earth orbit spacecraft. In this study, we have employed the Earth occultation technique combined with maximum likelihood estimation to estimate the neutral atmospheric density by modeling the attenuation of X-ray photons during the occultation process of Insight-HXMT observations of Crab Nebula. By comparing with blank sky occultation data, we demonstrate that the contribution from cosmic X-ray background can be negligible, which has allowed us to extended our density inversion up to 130 km altitude. This is a significant improvement over earlier work. Based on 83 occultation data sets of the Crab Nebula observed by all three sets of telescopes of Insight-HXMT between 2022 and 2024, we derived the atmospheric densities at altitudes spanning from 55 to 130 km. The results show a general agreement between our results and the predictions from the Navy Research Laboratory Mass Spectrometer Incoherent Scatter Radar Exosphere (NRLMSIS) model within the altitude ranges of 65–90, 95–100, and 120–130 km, particularly during periods of increased solar activity. These retrieved atmospheric density results between 65 and 90 km are consistent with prior studies. However, we also find that the NRLMSIS model overestimates atmospheric density at altitudes 90–95 and 100–120 km by 15%–20%. Furthermore, since the atmospheric density measurements at altitudes of 55–65 km may be subject to selection bias, we do not report the prediction accuracy of the NRLMSIS model at this altitude.}, archive = {J_ApJ}, author = {Hao-Hui Zhang and Wang-Chen Xue and Xiao-Bo Li and Shuang-Nan Zhang and Shao-Lin Xiong and Yong Chen and Hai-Tao Li and Li-Ming Song and Ming-Yu Ge and Hai-Sheng Zhao and Yun-Wei Yu}, doi = {10.3847/1538-4357/adec70}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {233}, shortjournal = {The Astrophys. J.}, title = {Measurement of neutral atmosphere density during the years of increasing solar activity using insight-HXMT data with the earth occultation technique}, volume = {988}, year = {2025}, }
• (2025). Validating solar atmosphere models with high-resolution spectra: The case of balmer lines. ApJ, 988(2), 232. (www)

  @article{ , abstract = {Stellar and solar atmosphere models are critical tools for numerous astrophysical applications, including the determination of stellar fundamental parameters, the study of stellar dynamos, and the characterization of exoplanetary atmospheres, habitability, and detectability. In the solar context, these models are indispensable for understanding how solar radiation and its variability influence Earth’s atmosphere and climate. High-resolution, spatially resolved observations offer an essential benchmark for assessing and improving the accuracy of existing atmospheric models. In this work, we compare synthetic Balmer line spectra, generated using one-dimensional, static, atmospheric models commonly employed to represent solar quiet regions, with state-of-the-art spectroscopic data obtained at the Institut für Astrophysik und Geophysik and the Göttingen Solar Tower at different positions over the solar disk. Our analysis indicates that, among the investigated models, Model 1001 by J. M. Fontenla et al. overall best reproduces observed properties of Balmer lines.}, archive = {J_ApJ}, author = {Serena Criscuoli and Adam F. Kowalski and Tyler Case and Odele Coddington}, doi = {10.3847/1538-4357/adec8e}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {232}, shortjournal = {The Astrophys. J.}, title = {Validating solar atmosphere models with high-resolution spectra: The case of balmer lines}, volume = {988}, year = {2025}, }
• (2025). Secular resonances in planet-hosting binary stars. II. application to terrestrial planet formation. ApJ, 988(2), 231. (www)

  @article{ , abstract = {Continuing our study of the effects of secular resonances on the formation of terrestrial planets in moderately close binary stars, we present here the results of an extensive numerical simulations of the formation of these objects. Considering a binary with two giant planets and a protoplanetary disk around its primary star, we have simulated the late stage of terrestrial planet formation for different types of the secondary, and different orbital elements of the binary and giant planets. Results demonstrate that terrestrial planet formation can indeed proceed constructively in such systems; however, as predicted by the general theory, secular resonances are suppressed and do not contribute to the formation process. Simulations show that it is in fact the mean-motion resonances of the inner giant planet that drive the dynamics of the protoplanetary disk and the mass and orbital architecture of the final bodies. Simulations also show that in the majority of the cases, the final systems contain only one terrestrial planet with a mass of 0.6–1.7 Earth masses. Multiple planets appear on rare occasions in the form of Earth–Mars analogs with the smaller planet in an exterior orbit. When giant planets are in larger orbits, the number of these double-planet systems increases and their planets become more massive. Results also show that when the orbits of the giant planets carry inclinations, while secular resonances are still suppressed, mean-motion resonances are strongly enhanced, drastically reducing the efficacy of the formation process. We present the results of our simulations and discuss their implications.}, archive = {J_ApJ}, author = {Nader Haghighipour and Michael Andrews}, doi = {10.3847/1538-4357/ade2dd}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {231}, shortjournal = {The Astrophys. J.}, title = {Secular resonances in planet-hosting binary stars. II. application to terrestrial planet formation}, volume = {988}, year = {2025}, }
• (2025). Shockingly effective: Cluster winds as engines of feedback in starburst galaxy VV 114. ApJ, 988(2), 230. (www)

  @article{ , abstract = {We present high-resolution Keck Cosmic Web Imager and MUSE integral field unit spectroscopy of VV 114, a local IR-luminous merger undergoing a vigorous starburst and showing evidence of galactic-scale feedback. The high-resolution data allow for spectral deblending of the optical emission lines and reveal a broad emission line component ( σ broad ∼ 100–300 km s −1 ) with line ratios and kinematics consistent with a mixture of ionization by stars and radiative shocks. The shock fraction (percentage of ionization due to shocks) in the high-velocity gas is anticorrelated with the projected surface number density of resolved star clusters, and we find that the radial density profiles around clusters are fit well by models of adiabatically expanding cluster winds driven by massive stellar winds and supernovae (SNe). The total kinetic power estimated from the cluster wind models matches the wind + SN mechanical energy deposition rate estimated from the soft-band X-ray luminosity, indicating that at least 70% of the shock luminosity in the galaxy is driven by the star clusters. Hubble Space Telescope narrowband near-IR imaging reveals embedded shocks in the dust-buried IR nucleus of VV 114E. Most of the shocked gas is blueshifted with respect to the quiescent medium, and there is a close spatial correspondence between the shock map and the Chandra soft-band X-ray image, implying the presence of a galactic superwind. The energy budget of the superwind is in close agreement with the total kinetic power of the cluster winds, confirming the superwind is driven by the starburst.}, archive = {J_ApJ}, author = {Justin A. Kader and Vivian U and Jeffrey A. Rich and Marina Bianchin and Sean T. Linden and Anne M. Medling and Tanio Diaz-Santos and George C. Privon and Rosalie McGurk and Lee Armus and Loreto Barcos-Mũnoz and Gabriela Canalizo and Vassilis Charmandaris and Aaron S. Evans and Tianmu Gao and Justin Howell and Hanae Inami and Thomas Lai and Kirsten L. Larson and Matthew A. Malkan and María Sánchez-García and Christopher D. Martin and Mateusz Matuszewski and Claire E. Max and Joseph M. Mazzarella and James D. Neill and Nikolaus Z. Prusinski and Raymond Remigio and David Sanders and Yiqing Song and Sabrina Stierwalt and Jason Surace}, doi = {10.3847/1538-4357/ade38e}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {230}, shortjournal = {The Astrophys. J.}, title = {Shockingly effective: Cluster winds as engines of feedback in starburst galaxy VV 114}, volume = {988}, year = {2025}, }
• (2025). Tracing dark matter in the central regions of galaxy clusters using galaxies, gas, and intracluster light in TNG300: Connections to cluster dynamical state. ApJ, 988(2), 229. (www)

  @article{ , abstract = {Recent studies have highlighted the potential of intracluster light (ICL) as a dark matter tracer. Moreover, ICL coevolves with the brightest cluster galaxy (BCG) and the host cluster, making it a valuable tool for understanding cluster dynamics. In this study, we utilize 426 galaxy clusters (with total mass M tot > 10 14 M ⊙ at z = 0) simulated in the cosmological hydrodynamical simulation Illustris TNG300 to compare the spatial distributions of dark matter, member galaxies, gas, and ICL and to assess their effectiveness as dark matter tracers in the central regions of clusters at R vir < 0.3. We apply the Weighted Overlap Coefficient, a methodology for quantifying the similarity of two-dimensional spatial distributions, to various components of the galaxy clusters at different dynamical stages. Our findings reveal that the spatial distributions of ICL combined with the BCG and gas closely resemble the dark matter distribution, with higher fidelity observed in more relaxed galaxy clusters with earlier half-mass epochs. These results demonstrate that the BCG+ICL component serves as an effective tracer of dark matter, consistent with previous observational studies linking cluster light to mass. Moreover, the degree of spatial similarity between the BCG+ICL and dark matter distributions appears to reflect the dynamical state of the cluster.}, archive = {J_ApJ}, author = {Jaewon Yoo and Jihye Shin and Ho Seong Hwang and Cristiano G. Sabiu and Hyowon Kim and Jongwan Ko and Jong Chul Lee}, doi = {10.3847/1538-4357/ade66f}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {229}, shortjournal = {The Astrophys. J.}, title = {Tracing dark matter in the central regions of galaxy clusters using galaxies, gas, and intracluster light in TNG300: Connections to cluster dynamical state}, volume = {988}, year = {2025}, }
• (2025). The binary fraction of B-type runaway stars from LAMOST DR8. ApJ, 988(2), 228. (www)

  @article{ , abstract = {Runaway stars are defined as stars that depart from their birth clusters at high peculiar velocities. There are two main mechanisms for the formation of runaway stars, i.e., the binary-supernova scenario (BSS) and the dynamical ejection scenario (DES). Investigating the binary fraction of runaway stars is an important step in further exploring the relative significance of the two mechanisms. We analyzed the binary fraction of 203 Galactic B-type runaway stars identified in the Large Sky Area Multi-Object Fiber Spectroscopic Telescope Data Release 8 database. Our analysis of radial velocity variations in the runaway star sample reveals an observed spectroscopic binary fraction of 5.4% ± 1.6%, representing the proportion of objects that exhibit statistically significant variations in radial velocity with amplitudes larger than 16 km s −1 . We employed a Monte Carlo method to correct for observational biases and determined an intrinsic binary fraction of 27% ± 8%. The period and mass ratio distributions that best reproduce the observation are f ( P ) ∝ P −5.7 for 1 ≤ P ≤ 1000 days, and f ( q ) ∝ q −3.6 for 0.1 ≤ q ≤ 1.0, indicating a preference for binaries with shorter periods and less massive companions compared to a uniform distribution. The intrinsic binary fraction, in combination with previous studies on the binary fractions of runaway stars formed by the BSS and the DES, implies that both scenarios contribute comparably to the formation of Galactic B-type runaway stars, where the ratio of the BSS to the DES is 0.86.}, archive = {J_ApJ}, author = {Kun Chen and Yanjun Guo and Dengkai Jiang and Zhanwen Han and Xuefei Chen}, doi = {10.3847/1538-4357/ade702}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {228}, shortjournal = {The Astrophys. J.}, title = {The binary fraction of B-type runaway stars from LAMOST DR8}, volume = {988}, year = {2025}, }
• (2025). Commensal transient searches with MeerKAT in gamma-ray burst and supernova fields. ApJ, 988(2), 227. (www)

  @article{ , abstract = {The sensitivity and field of view of the MeerKAT radio telescope provide excellent opportunities for commensal transient searches. We carry out a commensal transient search in supernova and short gamma-ray burst fields using methodologies established by S. I. Chastain et al. We search for transients in MeerKAT L-band images with integration times of 30 minutes, finding 13 variable sources. We compare these sources to the VLASS and RACS survey data, and examine possible explanations for the variability. Additionally, for one of these sources we examine archival Chandra ACIS data. We find that 12 of these sources are consistent with variability due to interstellar scintillation. The remaining source could possibly have some intrinsic variability. We also split the MeerKAT L band into upper and lower halves, and search for transients in images with an integration time of 8 s. We find a source with a duration of 8–16 s that is highly polarized at the lowest frequencies. This source is spatially coincident with a star detected by the Transiting Exoplanet Survey Satellite. We conclude that this source may be consistent with a stellar flare. Finally, we calculate accurate upper and lower limits on the transient rate using transient simulations.}, archive = {J_ApJ}, author = {S. I. Chastain and A. J. van der Horst and A. Horesh and A. Rowlinson and A. Andersson and R. Diretse and M. Vaccari and R. P. Fender and P. A. Woudt}, doi = {10.3847/1538-4357/ade70a}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {227}, shortjournal = {The Astrophys. J.}, title = {Commensal transient searches with MeerKAT in gamma-ray burst and supernova fields}, volume = {988}, year = {2025}, }
• (2025). Hydrous chondrites under shock. ApJ, 988(2), 226. (www)

  @article{ , abstract = {We examine the shock response of a chondrule-like multicomponent silicate melt enriched with 2 wt% H 2 O, representative of hydrous chondrites, using ab initio molecular dynamics. We calculate Hugoniot equations of state (HEOS) and evaluate how hydration affects transport, structural, and thermodynamic features under shock compression. Under the same initial conditions, our results show that water has a minimal direct effect on HEOS. However, the corresponding decrease in initial density significantly shifts the pressure–temperature trajectory. At constant shock pressures, hydration raises peak temperatures, altering volatile loss and melting behavior. The enhanced heating and melting caused by the presence of water implies that hydrated materials could have played a role in shaping the evolution of planetesimals. This challenges previous assumptions constructed on dry silicate models and suggests that volatile-rich bodies may have differentiated more efficiently. In shocked melts, the fast diffusion of hydrogen, compared to the cations, indicates its weak integration into the silicate network. Accordingly, we find that Si–H forms only transiently. Furthermore, analysis of the electron localization function supports the presence of bonded Si–H and Fe–H species along the HEOS, identified from a geometrical approach. The proportions of hydrides depend on the shock conditions and could affect the redox state of the melt, even when they are rare. Our results suggest that even a small amount of water in silicates influences the thermodynamics and chemical behavior during planetesimal impacts. These transformations should be considered in models of core formation and volatile depletion of early planetary bodies.}, archive = {J_ApJ}, author = {Adrien Saurety and Razvan Caracas}, doi = {10.3847/1538-4357/ade87f}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {226}, shortjournal = {The Astrophys. J.}, title = {Hydrous chondrites under shock}, volume = {988}, year = {2025}, }
• (2025). Constraining the milky way halo accretion history with simulated stellar halos: Designing the HALO7D-X survey. ApJ, 988(2), 225. (www)

  @article{ , abstract = {We present the design for HALO7D-X, a survey of the stellar halo to investigate the accretion history of the Milky Way. The survey will use a combination of Hubble Space Telescope (HST) and Gaia data for sky position and proper motions of faint stars (18 < G < 21.5 mag), while line-of-sight velocity, distance, [Fe/H], and [ α /Fe] will be measured using follow-up Keck spectroscopy. The survey will cover 30 lines of sight, made up of multiple HST archival fields and optimized for Keck DEIMOS spectroscopy. We use mock survey observations of the Bullock and Johnston stellar halo simulations to investigate the sensitivity of HALO7D-X to constrain the basic parameters of the accretion history of our Galaxy’s stellar halo. We find that we are sensitive to the mass distribution and accretion timeline of the stellar halo progenitors, but not their orbital circularity. We find that the simulated halos fall into three different groups based on the similarities in their distributions of the observable dimensions of our survey. These groups are also distinct from each other in the mass distribution and accretion timeline of their progenitor satellites, showing that by using similarities in our observables among halos, we are able to identify similarities in their accretion histories. With HALO7D-X, we will compare real Milky Way data with simulated halos and use this connection between observables and progenitor mass and accretion timeline to learn about the formation of our Galaxy’s stellar halo.}, archive = {J_ApJ}, author = {Miranda Apfel and Kevin McKinnon and Constance M. Rockosi and Puragra Guhathakurta and Kathryn V. Johnston}, doi = {10.3847/1538-4357/ade43d}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {225}, shortjournal = {The Astrophys. J.}, title = {Constraining the milky way halo accretion history with simulated stellar halos: Designing the HALO7D-X survey}, volume = {988}, year = {2025}, }
• (2025). Anomalously fast core and envelope rotation in red giants. ApJ, 988(2), 224. (www)

  @article{ , abstract = {Red giants undergo dramatic and complex structural transformations as they evolve. Angular momentum is transported between the core and envelope during this epoch, a poorly understood process. Here, we infer envelope and core rotation rates from Kepler observations of ∼1517 red giants. While many measurements are consistent with the existing studies, our investigation reveals systematic changes in the envelope-to-core rotation ratio and we report the discovery of anomalies such as clump stars with rapidly rotating cores and red giants with envelopes rotating faster than their cores. We propose binary interactions as a possible mechanism by which some of these cores and envelopes are spun up. These results pose challenges to current theoretical expectations and can have major implications for compact remnants born from stellar cores.}, archive = {J_ApJ}, author = {Siddharth Dhanpal and Othman Benomar and Shravan Hanasoge and Jim Fuller}, doi = {10.3847/1538-4357/ade2d1}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {224}, shortjournal = {The Astrophys. J.}, title = {Anomalously fast core and envelope rotation in red giants}, volume = {988}, year = {2025}, }
• (2025). Consequences of hot electrons for the structure of the outer heliosphere. ApJ, 988(2), 223. (www)

  @article{ , abstract = {The temperature of electrons is largely unknown in the outer heliosphere because there is a gap in Voyager measurements from ∼3 eV to 22 keV. Most models assume that the electrons have the same temperature as the bulk cold thermal solar wind (10 4 K beyond about 10 au from the Sun), but some studies argue that the electrons could be orders of magnitude hotter. We perform two global, multi-fluid magnetohydrodynamic simulations of the heliosphere: one with cold electrons (∼10 4 K) and one with hot electrons (∼10 6 K). The hot-electron case leads to an electron-pressure-dominated heliosheath, which expands the thickness of the heliosheath by 50% in the nose direction relative to the cold-electron case. In the tail, electron impact ionization is important with hot electrons and leads to a runaway ionization cascade that increases the plasma density by an order of magnitude. The cold case produces a short, turbulent, split, croissant-like tail, while the hot case creates a long, laminar, comet-like tail. The expansion of the heliosheath seen with hot electrons is inconsistent with the heliosheath thickness from Voyager measurements, but it is clear that the electron temperature has a strong effect on the heliosphere and must be constrained. We also show that the magnetosonic speed is variable in the heliosheath and not constant, which could affect estimates of the heliosheath thickness with pressure sounding methods.}, archive = {J_ApJ}, author = {Ethan Schuyler Bair and Merav Opher and Marc Zachary Kornbleuth and Bertalan Zieger and Gabor Toth and Bart van der Holst}, doi = {10.3847/1538-4357/ade437}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {223}, shortjournal = {The Astrophys. J.}, title = {Consequences of hot electrons for the structure of the outer heliosphere}, volume = {988}, year = {2025}, }
• (2025). Characterizing continuous gravitational waves from supermassive black hole binaries in realistic pulsar timing array data. ApJ, 988(2), 222. (www)

  @article{ , abstract = {Pulsar timing arrays recently found evidence for a gravitational-wave background (GWB), likely the stochastic overlap of gravitational waves from many supermassive black hole binaries. Anticipating a continuous gravitational-wave (CW) detection from a single binary soon to follow, we examine how well current Bayesian methods can detect CWs and characterize their binary properties by modeling the response of the NANOGrav 15 yr pulsar timing array to simulated binary populations. We run Markov Chain Monte Carlo searches for CWs in these data sets and compare them to quicker detection statistics including the optimal signal-to-noise ratio (S/N), matched filter detection statistic, and reduced log-likelihood ratio between the signal and noise models calculated at the injected parameters. The latter is the best proxy for Bayesian detection fractions, corresponding to a 50% detection fraction (by Bayes factors >10 favoring a CW detection over noise-only model) at an S/N = 4.6. Source confusion between the GWB and a CW, or between multiple CWs, can cause false detections and unexpected dismissals. Fifty-three percent of realistic binary populations consistent with the recently observed GWB have successful CW detections. Additionally, 82% of these CWs are in the fourth or fifth frequency bin of the 16.03 yr data set (6.9 and 10.8 nHz), with 95th percentile regions spanning 4–12 nHz frequencies, 0.7–20 × 10 9 M ⊙ chirp masses, 60 Mpc–8 Gpc luminosity distances, and 18–13,000 deg 2 68% confidence localization areas. These successful detections often poorly recover the chirp mass, with only 29% identifying the chirp mass accurately to within 1 dex with a 68% posterior width also narrower than 1 dex.}, archive = {J_ApJ}, author = {Emiko C. Gardiner and Bence Bécsy and Luke Zoltan Kelley and Neil J. Cornish}, doi = {10.3847/1538-4357/ade4c2}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {222}, shortjournal = {The Astrophys. J.}, title = {Characterizing continuous gravitational waves from supermassive black hole binaries in realistic pulsar timing array data}, volume = {988}, year = {2025}, }
• (2025). The importance of the population III initial mass function in determining the characteristics of the earliest galaxies. ApJ, 988(2), 221. (www)

  @article{ , abstract = {We use large-scale cosmological simulations to study the prospect of observing Population III (Pop III) bright galaxies with the James Webb Space Telescope (JWST). To quantify the impact of radiative transfer (RT), we compare a simulation that includes moment-based RT with one in which RT is handled approximately. Both simulations include a subgrid model of turbulent mixing, which is essential in tracking the formation of Pop III stars. We find that RT has a minor impact on our results, and that the overall star formation rate densities for both simulations are in fair agreement with observations and other simulations. While our overall galaxy luminosity functions are consistent with current high-redshift observations, we predict a drop of a factor of at least 6 in detectable galaxy counts at z = 14 as compared to z = 12 at M AB ≤ −16. Modeling Pop III stars according to a log-normal, top-heavy initial mass function (IMF), we find that these stars contribute no more than ≈1% of the flux of potentially detectable lensed galaxies at z = 12–14 with M AB ≤ −15. This is because a top-heavy Pop III IMF results in 99% of Pop III stellar mass being recycled within 10 Myr, well before the ≈30 Myr timescale on which galaxies recover from supernova feedback and heating. These effects conspire to quickly extinguish Pop III star formation, making their detection difficult even for JWST.}, archive = {J_ApJ}, author = {Richard Sarmento and Evan Scannapieco}, doi = {10.3847/1538-4357/ade78d}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {221}, shortjournal = {The Astrophys. J.}, title = {The importance of the population III initial mass function in determining the characteristics of the earliest galaxies}, volume = {988}, year = {2025}, }
• (2025). Follow the Mass—A concordance picture of tidal disruption events. ApJ, 988(2), 220. (www)

  @article{ , abstract = {Three recent global simulations of tidal disruption events (TDEs) have produced, using different numerical techniques and parameters, very similar pictures of their dynamics. In typical TDEs, after the star is disrupted by a supermassive black hole, the bound portion of the stellar debris follows highly eccentric trajectories, reaching apocenters of several thousand gravitational radii. Only a very small fraction is captured upon returning to the vicinity of the supermassive black hole. Nearly all of the debris returns to the apocenter, where shocks produce a thick irregular cloud on this radial scale and power the optical/UV flare. These simulation results imply that over a few years, the thick cloud settles into an accretion flow responsible for the long-term emission. Despite not being designed to match observations, and without any free parameters, the dynamical picture given by the three simulations aligns well with observations of typical events, correctly predicting the flares’ typical total radiated energy, luminosity, temperature, and emission-line width. On the basis of these predictions, we provide an updated method ( TDEmass ) to infer the stellar and black hole masses from a flare’s peak luminosity and temperature. This picture also correctly predicts that the luminosity observed years after the flare should be nearly constant. In addition, we show that in a magnitude-limited survey, if the intrinsic rate of TDEs is independent of black hole mass, the detected events will preferentially have black hole masses ∼10 6.3±0.3 M ⊙ and stellar masses ∼1 M ⊙ .}, archive = {J_ApJ}, author = {Julian Krolik and Tsvi Piran and Taeho Ryu}, doi = {10.3847/1538-4357/ade797}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {220}, shortjournal = {The Astrophys. J.}, title = {Follow the Mass—A concordance picture of tidal disruption events}, volume = {988}, year = {2025}, }
• (2025). High-resolution solar image registration using unsupervised deep learning. ApJ, 988(2), 219. (www)

  @article{ , abstract = {High-resolution solar images captured at different wavelengths are essential for understanding solar activity. However, such images often exhibit geometric discrepancies due to varying instrument resolutions and observation conditions, making image registration a critical preprocessing step. In this study, we propose an unsupervised deep learning–based framework named hourGlass and haRdnEt (GRE) for accurate solar image registration. The method detects keypoints in both the reference and moving images, extracts local feature descriptors, performs bidirectional matching to establish reliable correspondences, and estimates affine transformation parameters to align the images. The proposed framework was evaluated on quiet Sun images from the New Vacuum Solar Telescope and active region (AR) images from the Goode Solar Telescope, covering both photospheric and chromospheric features. A synthetic data set with known transformations was also used to assess registration accuracy under controlled conditions. Registration performance was quantitatively measured using mutual information (MI) and structural similarity index (SSIM) methods, and results were compared with those obtained using the scale-invariant feature transform and intensity-based two-step methods. The experimental results demonstrate that the proposed method achieves accurate registration across different solar features and imaging scenarios. The method maintains structural consistency in both AR and quiet Sun observations, including time-series data, with MI and SSIM improvements over baseline methods. The approach provides a validated tool for solar image alignment, suitable for further solar physics studies.}, archive = {J_ApJ}, author = {Hao Zhang and Bo Liang and Xiaoli Yan and Song Feng and Ding Yuan and Yunfang Cai and Wei Dai}, doi = {10.3847/1538-4357/adeb77}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {219}, shortjournal = {The Astrophys. J.}, title = {High-resolution solar image registration using unsupervised deep learning}, volume = {988}, year = {2025}, }
• (2025). Proper motion of the neutron star in the supernova remnant g18.9–1.1. ApJ, 988(2), 218. (www)

  @article{ , abstract = {In this paper, we present the first direct measurement of the proper motion of the neutron star (NS) in the supernova remnant (SNR) G18.9−1.1 using a 15 yr Chandra baseline. After correcting the observations’ astrometric solutions using reference Gaia stars’ positions, we measure a total proper motion of 24.7 ± 6.8 mas yr −1 at an angle of 336° ± 16° east of north. Using the distance estimates from the literature of 2.1 and 3.8 kpc, this proper motion corresponds to Galactic rotation-corrected transverse velocities of 264d 2.1 ± 79 km s −1 and 474d 3.8 ± 129 km s −1 , respectively. Our power ratio method analysis of SNR ejecta slightly favors the higher velocity, as multipole moments calculated from the back-evolved center using the farther distance are more consistent with values from other CCSNRs. The NS’s motion is directly opposite the motion of bulk ejecta in G18.9−1.1, providing yet more evidence that NS kicks are generated via a conservation of momentum-like process between the NS and the ejecta, as has been observed in other SNRs.}, archive = {J_ApJ}, author = {Tyler Holland-Ashford and Brian Williams and Patrick Slane and Xi Long}, doi = {10.3847/1538-4357/adeb7e}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {218}, shortjournal = {The Astrophys. J.}, title = {Proper motion of the neutron star in the supernova remnant g18.9–1.1}, volume = {988}, year = {2025}, }
• (2025). A map of the outer gas disk of the galaxy with direct distances from young stars. ApJ, 988(2), 217. (www)

  @article{ , abstract = {For more than 50 yr, astronomers have mapped the neutral hydrogen gas in the Galaxy assuming kinematically derived distances. We employ the distances of nearby young stars, which trace the gas from which they formed, in longitude–latitude–velocity space to map this gas without using kinematic distances. We denote this new method “pattern matching.” Analysis of simulated spiral galaxies indicates that our pattern matching distances are 24% more accurate than kinematic distances for gas within 15 kpc of the Sun. The two methods provide similar agreement with parallaxes toward these masers, although the kinematic method shows a small systematic offset in distance that is not present in the pattern matching distances. Using parallaxes and velocities for masers, we show that this novel method, when matched with nearby Cepheids, performs well compared to kinematics. This analysis is restricted to sources that have a reasonably good match with a member of our Cepheid sample. The distances derived here, and the associated map, have broad utility—from improving our understanding of star formation and the dynamical structure of the Galaxy, to informing 3D dust maps.}, archive = {J_ApJ}, author = {Peter Craig and Sukanya Chakrabarti and Alexander R. Pettitt and Robyn Sanderson and Erik Rosolowsky}, doi = {10.3847/1538-4357/ade232}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {217}, shortjournal = {The Astrophys. J.}, title = {A map of the outer gas disk of the galaxy with direct distances from young stars}, volume = {988}, year = {2025}, }
• (2025). The star formation in radio survey: Adding 90 GHz data to 3–33 GHz observations of star-forming regions in nearby galaxies. ApJ, 988(2), 216. (www)

  @article{ , abstract = {We present 90 GHz continuum imaging of 119 star-forming regions in 30 nearby galaxies observed with MUSTANG-2 on the Robert C. Byrd Green Bank Telescope as part of the Star Formation in Radio Survey. The 90 GHz data were combined with 3, 15, and 33 GHz data taken previously by the Karl G. Jansky Very Large Array to decompose radio spectra on ≈0.8 kpc scales into their synchrotron, free–free, and thermal dust emission components. This was done using three scenarios: (i) a power-law fit from 3 to 33 GHz, (ii) Markov Chain Monte Carlo (MCMC) fitting from 3 to 90 GHz with a thermal dust component, and (iii) MCMC fitting from 3 to 33 GHz without a thermal dust component. For these cases, we find a median thermal (free–free) emission fraction at 33 GHz of (i) 88% ± 2% with a scatter of 17%, (ii) 76% ± 3% with a scatter of 25%, and (iii) 84% ± 2% with a scatter of 18%. From this we conclude that, on average, free–free emission, not thermal dust, remains the dominant emission component at 33 GHz. While scenario (ii) yields a thermal fraction that is ≈10% larger than scenario (iii), this difference decreases to ≈5% after active galactic nuclei are removed. Consequently, star formation rates measured with thermal fractions at 33 GHz are only mildly biased high without 90 GHz data for the spectral decomposition. Furthermore, a power-law fit of data from 3 to 33 GHz still provides a reliable estimate of the free–free emission at 33 GHz.}, archive = {J_ApJ}, author = {Anna Dignan and Eric J. Murphy and Brian Mason and Cosima Eibensteiner and Brandon S. Hensley and Eric F. Jiménez-Andrade and Sean T. Linden and Simon R. Dicker and Dillon Z. Dong and Emmanuel Momjian and Charles E. Romero and Eva Schinnerer and Jean L. Turner}, doi = {10.3847/1538-4357/ade436}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {216}, shortjournal = {The Astrophys. J.}, title = {The star formation in radio survey: Adding 90 GHz data to 3–33 GHz observations of star-forming regions in nearby galaxies}, volume = {988}, year = {2025}, }
• (2025). Timescales of polycyclic aromatic hydrocarbon and dust continuum emission from gas clouds compared to molecular gas cloud lifetimes in PHANGS-JWST galaxies. ApJ, 988(2), 215. (www)

  @article{ , abstract = {Recent JWST mid-infrared (mid-IR) images, tracing polycyclic aromatic hydrocarbons (PAHs) and dust continuum emission, provide detailed views of the interstellar medium (ISM) in nearby galaxies. Leveraging PHANGS-JWST Cycle 1 and PHANGS-MUSE data, we measure the PAH and dust continuum emission lifetimes of gas clouds across 17 nearby star-forming galaxies by analyzing the relative spatial distributions of mid-IR (7.7–11.3 μ m) and H α emission at various scales. We find that the mid-IR emitting timescale of gas clouds in galactic disks (excluding centers) ranges from 10–30 Myr. After star formation is detected in H α , mid-IR emission persists for 3–7 Myr during the stellar feedback phase, covering 70%–80% of the H α emission. This significant overlap is due to intense radiation from star-forming regions, illuminating the surrounding PAHs and dust grains. In most galaxies, the mid-IR time-scale closely matches the molecular cloud lifetime measured with CO. Although mid-IR emission is complex, as influenced by ISM distribution, radiation, and abundances of dust and PAHs, the similarity between the two timescales suggests that once gas clouds form with compact mid-IR emission, they quickly provide sufficient shielding for stable CO formation. This is likely due to our focus on molecular gas-rich regions of galaxies with near-solar metallicity. Finally, we find that the mid-IR emitting timescale is longer in galaxies with well-defined H ii regions and less structured backgrounds, allowing photons to more efficiently heat the ambient ISM surrounding the H ii regions, rather than contributing to diffuse emission. This suggests that the shape of the ISM also influences mid-IR emission.}, archive = {J_ApJ}, author = {Jaeyeon Kim and Mélanie Chevance and Lise Ramambason and Kathryn Kreckel and Ralf S. Klessen and Daniel A. Dale and Adam K. Leroy and Karin Sandstrom and Ryan Chown and Thomas G. Williams and Sumit K. Sarbadhicary and Francesco Belfiore and Frank Bigiel and Enrico Congiu and Oleg V. Egorov and Eric Emsellem and Simon C. O. Glover and Kathryn Grasha and Annie Hughes and J. M. Diederik Kruijssen and Janice C. Lee and Debosmita Pathak and Ismael Pessa and Erik Rosolowsky and Jiayi Sun and Jessica Sutter and David A. Thilker}, doi = {10.3847/1538-4357/ade443}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {215}, shortjournal = {The Astrophys. J.}, title = {Timescales of polycyclic aromatic hydrocarbon and dust continuum emission from gas clouds compared to molecular gas cloud lifetimes in PHANGS-JWST galaxies}, volume = {988}, year = {2025}, }
• (2025). Modeling cosmic-ray electron spectra and synchrotron emission in the multiphase interstellar medium. ApJ, 988(2), 214. (www)

  @article{ , abstract = {We model the transport and spectral evolution of 1–100 GeV cosmic-ray electrons (CREs) in TIGRESS magnetohydrodynamic simulations of the magnetized, multiphase interstellar medium. We postprocess a kpc-sized galactic disk patch representative of the solar neighborhood using a two-moment method for cosmic ray (CR) transport that includes advection, streaming, and diffusion. The diffusion coefficient is set by balancing wave growth via the CR streaming instability against wave damping (nonlinear Landau and ion–neutral collisions), depending on local gas and CR properties. Implemented energy loss mechanisms include synchrotron, inverse Compton, ionization, and bremsstrahlung. We evaluate CRE losses by different mechanisms as a function of energy and distance from the midplane, and compare loss timescales to transport and diffusion timescales. This comparison shows that CRE spectral steepening above p = 1 GeV c −1 is due to a combination of energy-dependent transport and losses. Our evolved CRE spectra are consistent with direct observations in the solar neighborhood, with a spectral index that steepens from an injected value of −2.3 to an energy-dependent value between −2.7 and −3.3. We also show that the steepening is independent of the injection spectrum. Finally, we present potential applications of our models, including to the production of synthetic synchrotron emission. Our simulations demonstrate that the CRE spectral slope can be accurately recovered from pairs of radio observations in the range 1.5–45 GHz.}, archive = {J_ApJ}, author = {Nora B. Linzer and Lucia Armillotta and Eve C. Ostriker and Eliot Quataert}, doi = {10.3847/1538-4357/ade5ad}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {214}, shortjournal = {The Astrophys. J.}, title = {Modeling cosmic-ray electron spectra and synchrotron emission in the multiphase interstellar medium}, volume = {988}, year = {2025}, }
• (2025). A possible source of multiple polarity reversals of the polar magnetic field during the maximum phase of solar cycle. ApJ, 988(2), 213. (www)

  @article{ , abstract = {During the maximum phase of solar activity, it is quite common for the polar magnetic field to undergo multiple polarity reversals. In this study, we aim to provide the likely source of this phenomenon. By analyzing synoptic magnetograms from the Michelson Doppler Imagers on the Solar and Helioseismic Observatory and the Helioseismic and Magnetic Imager on the Solar Dynamics Observatory throughout Solar Cycle 24, we have identified magnetic structures with densely packed fields by setting area and magnetic field thresholds. These structures are then coupled as bipolar magnetic regions (BMRs) by visual recognition, representing the active regions (ARs) composed of positive and negative polarities. In total, we extracted over 700 BMRs during Solar Cycle 24. Interestingly, we discovered that approximately one-third of these BMRs do not conform to Hale's polarity rule or Joy's law and are thus classified as irregular ARs or abnormal ARs. These irregular ARs distribute in various phases of Solar Cycle 24 and play a negative role in the polar field according to the Babcock–Leighton solar dynamo model. Further, our study shifts to the evolution of these irregular ARs with the obvious poleward flux diffusion and reveals that these ARs indeed produce poleward surges of magnetic flux with opposite polarity in the hemisphere. These findings suggest that these irregular ARs result in the fluctuation of the polar field and even the multiple polarity reversals of the polar field when they emerge during solar maximum.}, archive = {J_ApJ}, author = {Chunlan Jin and Shuhong Yang and Guiping Zhou and Jialiang Hu and Jingxiu Wang}, doi = {10.3847/1538-4357/ade681}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {213}, shortjournal = {The Astrophys. J.}, title = {A possible source of multiple polarity reversals of the polar magnetic field during the maximum phase of solar cycle}, volume = {988}, year = {2025}, }
• (2025). The sun’s dark core: Helioseismic and neutrino flux constraints on a compact solar center. ApJ, 988(2), 212. (www)

  @article{ , abstract = {As dark matter appears to comprise most of the Galactic mass, some of it may accumulate in the cores of stars, thereby making the Sun a laboratory for constraining various dark matter theories. We consider the effects on the solar structure arising from a general class of macroscopic dark matter candidates that include strange quark matter, compact dark objects, and others. We calibrate standard solar evolution models (i.e., models that reproduce the mass, luminosity, radius, and metallicity of the Sun at its present age) with variable compact dark core masses ranging from 10 −8 to 10 −2 M ⊙ and assess their properties. We find that the weakest constraints come from solar neutrino flux measurements, which only rule out the most massive dark core comprising at least ∼1% of the total solar mass. The Sun’s acoustic oscillations impose stronger constraints, probing masses down to ∼10 −5 M ⊙ . We find that a model with a 10 −3 M ⊙ dark core appears to improve the agreement with helioseismic observations. We nevertheless caution against interpreting this as evidence for dark matter in the solar interior, and suggest plausible effects that the dark core may instead be emulating. Finally, we show that future measurements of solar g- modes may constrain dark core masses down to 10 −7 M ⊙ .}, archive = {J_ApJ}, author = {Earl P. Bellinger and Matt E. Caplan}, doi = {10.3847/1538-4357/ade70f}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {212}, shortjournal = {The Astrophys. J.}, title = {The sun’s dark core: Helioseismic and neutrino flux constraints on a compact solar center}, volume = {988}, year = {2025}, }
• (2025). Suppression of shock X-ray emission in novae from turbulent mixing with cool gas. ApJ, 988(2), 211. (www)

  @article{ , abstract = {Shock interaction in classical novae occurs when a fast outflow from the white dwarf ≳1000 km s −1 collides with a slower, cooler shell of gas released earlier in the outburst. The shocks radiate across the electromagnetic spectrum, from radio synchrotron to GeV gamma rays. The hot shocked gas also emits ≳keV thermal X-rays, typically peaking weeks after the eruption, once the ejecta become transparent to photoelectric absorption. However, the observed hard X-ray luminosities are typically ≳4 orders of magnitude smaller than would be naively expected given the powerful shocks implied by the gamma rays. We argue that a key missing piece to this puzzle is turbulence behind the shock, driven, e.g., by thin-shell and/or thermal instabilities. Turbulence efficiently mixes the hot X-ray emitting gas with cooler gas, sapping the hot gas of energy faster than it can directly radiate. Using analytic arguments motivated by numerical simulations, we show that energy losses due to turbulent mixing can easily balance shock heating, greatly reducing the volume of the hot gas and suppressing the X-ray luminosity. Equating the characteristic thickness of the X-ray emitting region to the minimum outer length scale of the turbulence capable of cooling the hot gas through mixing, we obtain X-ray luminosities consistent with nova observations if only ∼1% of the shock’s kinetic power goes into turbulent motions. A similar process may act to suppress thermal X-rays from other shock powered transients, such as interacting supernovae.}, archive = {J_ApJ}, author = {Brian D. Metzger and Lachlan Lancaster and Rebecca Diesing}, doi = {10.3847/1538-4357/ade711}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {211}, shortjournal = {The Astrophys. J.}, title = {Suppression of shock X-ray emission in novae from turbulent mixing with cool gas}, volume = {988}, year = {2025}, }
• (2025). The effect of plasma-β on the heating mechanisms during magnetic reconnection in partially ionized low solar atmosphere. ApJ, 988(2), 210. (www)

  @article{ , abstract = {We performed numerical simulations of magnetic reconnection with different strengths of magnetic fields from the solar photosphere to the upper chromosphere. The main emphasis is to identify dominant mechanisms for heating plasmas in the reconnection region under different plasma- β conditions in the partially ionized low solar atmosphere. The numerical results show that more plasmoids are generated in a lower β reconnection event. The frequent coalescence of these plasmoids leads to a significant enhancement of turbulence and compression heating, which becomes the dominant mechanism for heating plasma in a lower plasma- β reconnection process. The average power density of the compression heating ( Q comp ) decreases with increasing initial plasma- β as a power function: {Q}_{\mathrm{comp}}\sim {\beta }_{0}^{-a} , where the value a is 1.9 in the photosphere and decreases to about 1.29 in the upper chromosphere. In the photosphere and lower chromosphere, the Joule heating contributed by electron-neutral collisions Q en = η en J 2 eventually dominates over the compression heating when the initial plasma- β is larger than the critical value β 0−critical = 8. In the upper chromosphere, the ambipolar diffusion heating and the viscous heating will become equally important as the compression heating when the initial plasma- β is larger than the critical value β 0−critical = 0.5. These results indicate that the compression heating caused by turbulent reconnection mediated with plasmoids is likely the major heating mechanism for the small-scale reconnection events with stronger magnetic fields, such as active region Ellerman bombs (EBs) and UV bursts. However, the heating caused by the partial ionization effects can not be ignored for those reconnection events with weaker magnetic fields, such as quiet Sun EBs and cold surges.}, archive = {J_ApJ}, author = {Abdullah Zafar and Lei Ni and Kaifeng Kang and Guanchong Cheng and Jing Ye and Jun Lin and Ahmad Ali and Nadia Imtiaz}, doi = {10.3847/1538-4357/ade714}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {210}, shortjournal = {The Astrophys. J.}, title = {The effect of plasma-β on the heating mechanisms during magnetic reconnection in partially ionized low solar atmosphere}, volume = {988}, year = {2025}, }
• (2025). Early and extensive ultraviolet through near infrared observations of the intermediate-luminosity type iax supernovae 2024pxl. ApJ, 988(2), 209. (www)

  @article{ , abstract = {We present ultraviolet (UV) through near-infrared (NIR) photometric and spectroscopic observations of the nearby SN 2024pxl, the third Type Ia supernova (SN Ia) in NGC 6384. SN 2024pxl is a Type Iax supernova (SN Iax) with an intermediate luminosity ( M r = −16.99 ± 0.32 mag) and an average SN Iax light curve decline rate. SN 2024pxl was discovered ∼3 days after first light, and the rising light curve follows a single power law that is inconsistent with significant interaction with a companion star or circumstellar material. Our extensive NIR photometric coverage is comparable to that of the well-observed SNe Iax 2005hk and 2012Z, and we demonstrate that the J − H colors of SNe Iax differ from normal SNe Ia and appear to be more homogeneous as a class. Spectroscopically, we report the earliest-ever NIR spectrum of an SN Iax as measured from maximum light ( t ≈ −9 days): a featureless continuum with similarities to a ∼9000 K blackbody, and the line velocities are consistent with a mixed-ejecta structure, with C, Si, and Fe having similar velocities and velocity evolutions. We find a tentative correlation between the H -band break Co ii velocity ∼20 days post-peak and absolute magnitude, with more luminous SNe Iax showing faster Co ii velocities. Our observations suggest that SN 2024pxl resulted from the thermonuclear disruption of a CO white dwarf star that undergoes deflagration burning.}, archive = {J_ApJ}, author = {W. B. Hoogendam and C. Ashall and D. O. Jones and B. J. Shappee and M. A. Tucker and M. E. Huber and K. Auchettl and D. D. Desai and A. Do and J. T. Hinkle and M. Y. Kong and S. Romagnoli and J. Shi and A. Syncatto and C. D. Kilpatrick}, doi = {10.3847/1538-4357/ade787}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {209}, shortjournal = {The Astrophys. J.}, title = {Early and extensive ultraviolet through near infrared observations of the intermediate-luminosity type iax supernovae 2024pxl}, volume = {988}, year = {2025}, }
• (2025). Thermodynamic characterization of solar wind interaction regions using PSP observations: Evidence of subadiabatic and superadiabatic states. ApJ, 988(2), 208. (www)

  @article{ , abstract = {This study provides a detailed analysis of the thermodynamic behavior within stream interaction regions (SIRs), focusing on an effective polytropic index assessment of 25 distinct events. To improve the accuracy of the effective polytropic index estimation, we applied a multistep filtering method based on the Bernoulli integral to remove outliers caused by streamline mixing and correlation coefficients to improve the applicability of the polytropic model. Considering the effective degree of freedom ( f = 3), 6 out of the 25 analyzed events show superadiabatic behavior, and the remaining events span subadiabatic, adiabatic, and superadiabatic states. The distribution of the determined polytropic indices for all the events reveals two distinct thermodynamic regimes, with peaks at γ = 1.22 (subadiabatic) and γ = 2.34 (superadiabatic). This analysis offers valuable insights into the complex thermodynamic processes occurring within solar wind interactions. The effective polytropic index of the solar wind does not have a single characteristic value throughout the heliosphere. Instead, it reflects varying heating and cooling processes and/or degrees of freedom within these structures, contributing to a deeper understanding of SIR dynamics.}, archive = {J_ApJ}, author = {Mohit Shah and Anil Raghav and Kalpesh Ghag and Omkar Dhamane and Kishor Kumbhar and Georgios Nicolaou and Ankush Bhaskar and R. C. Allen and Zubair Shaikh}, doi = {10.3847/1538-4357/ade9a3}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {208}, shortjournal = {The Astrophys. J.}, title = {Thermodynamic characterization of solar wind interaction regions using PSP observations: Evidence of subadiabatic and superadiabatic states}, volume = {988}, year = {2025}, }
• (2025). The physical mechanism of radio-quiet turn-on changing-look active galactic nuclei. ApJ, 988(2), 207. (www)

  @article{ , abstract = {It is suggested that the variation of the mass accretion rate in the accretion disk may be responsible for the occurrence of most changing-look active galactic nuclei (CL AGNs). However, the viscous timescale of a thin disk is far longer than the observed timescale of CL AGNs. Though this problem can be resolved by introducing the large-scale magnetic field, the mechanism for radio-quiet CL AGNs with a weak/absent large-scale magnetic field remains a mystery. In this work, we assume that the thin accretion disk is collapsed from the inner advection-dominated accretion flow (ADAF) instead of being formed from the outer thin disk through advection. This idea is tested by comparing the cooling timescale ( t cool ) of an ADAF with the observed timescale ( t tran ) of turn-on CL AGNs. We compile a sample of 102 turn-on CL AGNs from the archived data and calculate the cooling timescale of an ADAF with the critical mass accretion rate based on some conventional assumptions. It is found that t cool is much shorter than t tran in most of the CL AGNs, which validates our assumption, though t cool is not consistent with t tran ( t cool < t tran ). However, this is reasonable since most of the CL AGNs were observed only two times, indicating that the observed timescale t tran is the maximum value because the changing-look behavior can indeed happen before the second observation.}, archive = {J_ApJ}, author = {Shuang-Liang Li and Xinwu Cao}, doi = {10.3847/1538-4357/adec76}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {207}, shortjournal = {The Astrophys. J.}, title = {The physical mechanism of radio-quiet turn-on changing-look active galactic nuclei}, volume = {988}, year = {2025}, }
• (2025). Gaussian process modeling coronal X-ray variability of active galactic nuclei. ApJ, 988(2), 206. (www)

  @article{ , abstract = {The corona is an integral component of active galactic nuclei (AGNs) that can produce the X-ray emission. However, many of its physical properties and the mechanisms powering this emission remain a mystery. In this work, we study the coronal X-ray variabilities of 13 AGNs by the Gaussian process. Overall, 2–10 keV light curves of 13 AGNs can be successfully described by the damped random walk model. The extracted coronal X-ray timescales range from 3 to 50 days. In the plot of variability timescale versus black hole mass, the coronal X-ray timescales of four sources occupy almost the same region as the optical timescales of the accretion disk, with the latter matching the predicted thermal instability timescale of the disk. In contrast, the X-ray timescales of the remaining sources exhibit a systematic offset toward lower values. We propose that the coronal X-ray variability may be driven by internal processes within the corona itself (such as thermal conduction). On the other hand, it may also be triggered by local thermal instabilities occurring in different regions (close to the central black hole) of the accretion disk, which propagate to the corona via disk–corona coupling.}, archive = {J_ApJ}, author = {Haiyun Zhang and Dahai Yan and Li Zhang and Niansheng Tang}, doi = {10.3847/1538-4357/adec92}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {206}, shortjournal = {The Astrophys. J.}, title = {Gaussian process modeling coronal X-ray variability of active galactic nuclei}, volume = {988}, year = {2025}, }
• (2025). N-body simulations of galaxy bars generated by satellite collisions: Effects of the impact geometry. ApJ, 988(2), 205. (www)

  @article{ , abstract = {Bars, a common and important structure in disk galaxies, can be induced by galaxy interactions. Although there have been some studies on bar formation in flybys or collisions, the vast parameter space still leaves many scenarios that require further investigation. Here, we focus on the role of collisions caused by small galaxies (denoted as intruders), referred to as satellite collisions, in bar formation for MW/M31-like galaxies (denoted as target galaxies). Multiple sets of simulations with varying intruder initial velocities, inclination angles, collision positions, and intruder masses were run to study the dependence of this mechanism on these parameters. Our simulations show that bar formation favors moderate collision velocity, large inclination angle, off-center collision position, and large intruder mass. However, the bar’s pattern speed and length are insensitive to these parameters, as the intruder’s mass is relatively small compared to that of the target galaxy itself. Moreover, based on our tests, the intruder mass should be more than ∼3 × 10 9 M ⊙ in order for this bar formation mechanism to operate effectively in MW/M31-like galaxies. Our work suggests the possibility that satellite collisions may have contributed, to some extent, to the bar formation in the Milky Way or M31.}, archive = {J_ApJ}, author = {Yufan Fane Zhou and Zhiyuan Li and Hui Li}, doi = {10.3847/1538-4357/aded87}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {205}, shortjournal = {The Astrophys. J.}, title = {N-body simulations of galaxy bars generated by satellite collisions: Effects of the impact geometry}, volume = {988}, year = {2025}, }
• (2025). Estimating bolometric luminosities of type 1 quasars with self-organizing maps. ApJ, 988(2), 204. (www)

  @article{ , abstract = {We present a new method to calculate bolometric luminosities for unobscured, type 1 quasars with multiband photometric data. Bolometric luminosity is a fundamental property for understanding quasars, and it is commonly estimated from monochromatic luminosities using bolometric corrections that often neglect quasar spectral energy distribution (SED) diversity. We take advantage of the fact that most quasars now have multiband observations from UV to mid-IR and construct SEDs for a well-defined sample of Sloan Digital Sky Survey (SDSS) quasars at 0.5 ≤ z ≤ 2. Based on this fiducial sample, we explore quasar SEDs, their diversity, and their relations with bolometric luminosities. We then use unsupervised neural network self-organizing maps (SOM) to describe the SED diversity and compute the bolometric luminosities with a fully trained SOM model. This method reduces systematical uncertainties compared to the traditional method. In addition, we update the multilinear regression relations between bolometric luminosity and monochromatic luminosities at rest frame 1450 Å, 3000 Å, and 5100 Å. Our method is applicable to large quasar samples with a wide range of luminosity and redshift. We have applied it to the SDSS Data Release 16 quasars. We have also made our code publicly available.}, archive = {J_ApJ}, author = {Jie Chen and Linhua Jiang and Shengxiu Sun and Zijian Zhang and Mouyuan Sun}, doi = {10.3847/1538-4357/ade307}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {204}, shortjournal = {The Astrophys. J.}, title = {Estimating bolometric luminosities of type 1 quasars with self-organizing maps}, volume = {988}, year = {2025}, }
• (2025). Radio prospects of extrasolar aurorae polaris as a probe of planetary magnetism. ApJ, 988(2), 203. (www)

  @article{ , abstract = {Magnetized exoplanets are expected to emit auroral cyclotron radiation in the radio regime due to the interactions between their magnetospheres, the interplanetary magnetic field, and the stellar wind. Prospective extrasolar auroral emission detections will constrain the magnetic properties of exoplanets, allowing the assessment of the planets’ habitability and their protection against atmospheric escape by photoevaporation, enhancing our understanding of exoplanet formation and demographics. We construct a numerical model to update the estimates of radio emission characteristics of confirmed exoplanets while quantifying the uncertainties of our predictions for each system by implementing a Monte Carlo error propagation method. We identify 16 candidates that have expected emission characteristics that render them potentially detectable from current ground-based telescopes. Among these, the hot Jupiter tau Boötis b is the most favorable target, with an expected flux density of {51}_{-22}^{+36} mJy. Notably, 11 candidates are super-Earths and sub-Neptunes, for which magnetism is key to understanding the associated demographics. Together with the other predictive works in the literature regarding the characteristics and the geometry of magnetospheric emissions, our predictions are expected to guide observational campaigns in pursuit of discovering magnetism on exoplanets.}, archive = {J_ApJ}, author = {Asaf Kaya and Tansu Daylan}, doi = {10.3847/1538-4357/adde5c}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {203}, shortjournal = {The Astrophys. J.}, title = {Radio prospects of extrasolar aurorae polaris as a probe of planetary magnetism}, volume = {988}, year = {2025}, }
• (2025). Time-integrated polarization of structured jets in gamma-ray burst prompt emission. ApJ, 988(2), 202. (www)

  @article{ , abstract = {The structure of gamma-ray burst (GRB) jets remains one of the most significant open questions in high-energy astrophysics. Observations of events like GRB 170817A, associated with gravitational waves, and the exceptionally bright GRB 221009A suggest that jets may be structured rather than uniform. Polarization studies offer a powerful tool to probe jet structures, complementing traditional spectral analyses. This study examines the polarization degree (PD) of two types of structured jets under different magnetic field configurations (MFCs). The first type features a core with constant energy per unit solid angle, transitioning to a power-law decay at the edges. The second type exhibits a continuous decay of both energy per unit solid angle and Lorentz factor, controlled by a decay index. Additionally, motivated by jet-ambient medium interactions, we introduce a structured magnetic field model: the jet core region is dominated by an ordered magnetic field, while the ratio of ordered to random field strengths in the jet outer region follows a power-law decay. The results show that structured jets with ordered magnetic fields exhibit higher PD than uniform jets, especially when viewed off-axis, while random magnetic fields have minimal impact on structured jet PD. The PD difference between on-axis and off-axis observations decreases for jets with a shallow decay index, contrasting with uniform jets. If observed, PD shows little variation with fluence ratio, which strongly indicates a structured jet. Furthermore, within the structured magnetic field framework, random fields generally suppress polarization, but the random MFC can enhance off-axis polarization to some extent.}, archive = {J_ApJ}, author = {Qiannan Mai and Hongbang Liu and Jiangchuan Tuo and Zuke Feng and Qian Zhong and Kangfa Cheng and Jirong Mao and Enwei Liang}, doi = {10.3847/1538-4357/ade4c4}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {202}, shortjournal = {The Astrophys. J.}, title = {Time-integrated polarization of structured jets in gamma-ray burst prompt emission}, volume = {988}, year = {2025}, }
• (2025). Detection of four intermediate-mass stars with cool companions in low mass ratio eclipsing binaries. ApJ, 988(2), 201. (www)

  @article{ , abstract = {According to the core fragmentation and dynamical capture theories of binary formation, binaries tend to form with nearly equal masses. The detection of intermediate-mass binaries with low mass ratios challenges these theories, as such binaries may form via disk fragmentation and are very important to investigate binary formation and evolution. However, there are few confirmed samples to robustly test theories of the formation and evolution of binaries due to observational challenges. The development of high-precision space telescopes brings opportunities to study such samples. Based on TESS data, we present the first study on four intermediate-mass eclipsing binaries with the Wilson–Devinney method, which are: TIC 283881816, TIC 343757299, TIC 72444347, and TIC 353077789. All are totally detached eclipsing binaries with q < 0.4. TIC 283881816, TIC 343757299, and TIC 72444347 are A-type binaries with mass ratios of q = 0.34, 0.28, 0.39, respectively. TIC 353077789 is a B-type binary with an extremely low mass ratio of q = 0.18. These low mass ratio systems imply that they are highly likely to be formed via disk fragmentation and will undergo a common envelope evolution. Particularly, TIC 72444347 with a period of 4 \mathop{.}\limits^{{\rm{d}}} 4 still shows an eccentric orbit, while TIC 343757299 with a longer period (5 \mathop{.}\limits^{{\rm{d}}} 8) does not, which poses a challenge to the Kraft break. By plotting these components in the H-R diagram, it hints that all systems are main-sequence (MS) primaries with pre-MS companions. They are valuable targets for testing theories of binary formation and evolution.}, archive = {J_ApJ}, author = {Linfeng Chang and Shengbang Qian and Lei Zang and Fuxing Li}, doi = {10.3847/1538-4357/ade704}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {201}, shortjournal = {The Astrophys. J.}, title = {Detection of four intermediate-mass stars with cool companions in low mass ratio eclipsing binaries}, volume = {988}, year = {2025}, }
• (2025). The vela pulsar and its pulsar wind nebula vela-X using 13 yr of fermi-LAT observations. ApJ, 988(2), 200. (www)

  @article{ , abstract = {We present results of more than 13 yr of Fermi–Large Area Telescope (LAT) data analysis for the Vela pulsar from 60 MeV to 100 GeV and its pulsar wind nebula (PWN), Vela X, for E > 1 GeV in the off-pulse phases. We find that the Vela X PWN can be best characterized using two extended components: a large radial Gaussian accompanied by an offset, compact radial disk, both with a similar spectral index, Γ ∼ 2.3. The common spectral properties support a common PWN origin, but a supernova remnant component is plausible for the compact radial disk. With an updated Vela X model, the phase-resolved spectral properties of the Vela pulsar are explored through a phase-resolved analysis. The phase-resolved spectral properties of the pulsar, such as the spectral energy distribution (SED) peak energy E p , the width of the SED at its peak d p , and the asymptotic (low-energy) spectral index Γ 0 , are presented. The best-fit spectral models for each LAT pulse peak (Peak 1 and Peak 2) are extrapolated to UV energies and compared to archival, phase-resolved spectra at UV, X-ray, soft γ- ray, and TeV energies. We also discuss the physical implications of our modeling and the data comparisons.}, archive = {J_ApJ}, author = {Alexander Lange and J. Eagle and O. Kargaltsev and Lucien Kuiper and Jeremy Hare}, doi = {10.3847/1538-4357/ade713}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {200}, shortjournal = {The Astrophys. J.}, title = {The vela pulsar and its pulsar wind nebula vela-X using 13 yr of fermi-LAT observations}, volume = {988}, year = {2025}, }
• (2025). A glimpse of satellite galaxies in the milky way with the 2.5 m wide field survey telescope (WFST): Boötes III and draco. ApJ, 988(2), 199. (www)

  @article{ , abstract = {We carry out deep imaging of the Milky Way satellite galaxies, Boötes III and Draco, with the Wide Field Survey Telescope (WFST) as one pilot observing program to demonstrate the capability of WFST. Combining catalogs with PS1 DR2 and Gaia DR3, we derive proper motions for candidate member stars in these two satellite galaxies over a 12 yr time baseline, yielding uncertainties of ∼1.8 mas yr −1 at 21 mag and ∼3.0 mas yr −1 at 22 mag in the r band. The proper motions derived from bright and faint stars are consistent, indicating no significant variation in proper motion across stellar luminosity as these galaxies undergo tidal interactions with the Milky Way (MW). Meanwhile, we suggest that Boötes III represents the bound remnant of the progenitor galaxy that gave rise to the Styx stream, as evidenced by its elongated density profile and overdensity in both spatial and kinematic space. This is the first paper to use WFST to measure the proper motions of faint stars in MW satellite galaxies. More detailed analyses will be presented in forthcoming papers from the wide field survey program.}, archive = {J_ApJ}, author = {Chao Yang and Zhizheng Pan and Min Fang and Xian Zhong Zheng and Binyang Liu and Guoliang Li and Tian-Rui Sun and Ji-An Jiang and Miaomiao Zhang and Zhen Wan and Shuang Liu and Han Qu and Ji Yang and Xu Kong and Wenhao Liu and Yiping Shu and Jiang Chang and Tinggui Wang and Lulu Fan and Yongquan Xue and Wentao Luo and Hongxin Zhang and Zheng Lou and Haibin Zhao and Bin Li and Hairen Wang and Dazhi Yao and Jian Wang and Hongfei Zhang and Feng Li and Hao Liu and Ming Liang and Jinlong Tang and Yuheng Zhang and Man Qiao and Run Wen and Zongfei Lyu}, doi = {10.3847/1538-4357/ade78e}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {199}, shortjournal = {The Astrophys. J.}, title = {A glimpse of satellite galaxies in the milky way with the 2.5 m wide field survey telescope (WFST): Boötes III and draco}, volume = {988}, year = {2025}, }
• (2025). The influence of the nuclear shadowing effect on astrophysical neutrino flux. ApJ, 988(2), 198. (www)

  @article{ , abstract = {The production of neutrinos from ultrahigh-energy cosmic rays (UHECRs) is modulated by nuclear shadowing effects that are often overlooked in theoretical models. Nuclear shadowing, the suppression of pion production in photonuclear interactions within heavy nuclei, plays a critical role in determining neutrino yields. Current predictions frequently assume that UHECRs are proton-dominated and neglect the nuclear medium’s influence on pion cross sections, leading to overestimates of neutrino fluxes. Here, we incorporate nuclear shadowing effects into simulations of proton–photon ( pγ ) and proton–proton ( pp ) interactions in astrophysical source environments. We also account for nuclear photodisintegration in pγ processes, which further modifies secondary particle production. We integrate these effects into pure composition scenarios ( p , He, N, and Fe) to calculate the resultant neutrino background flux. Our results demonstrate that nuclear shadowing can reduce neutrino fluxes from heavy nuclei by a factor of 2–3 compared to proton-only scenarios.}, archive = {J_ApJ}, author = {Z. Y. Liu and H. Y. Yang and Y. G. Zheng and C. Y. Yang}, doi = {10.3847/1538-4357/adea48}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {198}, shortjournal = {The Astrophys. J.}, title = {The influence of the nuclear shadowing effect on astrophysical neutrino flux}, volume = {988}, year = {2025}, }
• (2025). Galactic magnetic fields. II. applying the model to nearby galaxies. ApJ, 988(2), 197. (www)

  @article{ , abstract = {Many spiral galaxies host magnetic fields with energy densities comparable to those of the turbulent and thermal motions of their interstellar gas. However, quantitative comparison between magnetic field properties inferred from observation and those obtained from theoretical modeling has been lacking. In L. Chamandy et al. (Paper I ), we developed a simple, axisymmetric galactic dynamo model that uses various observational data as input. Here, we apply our model to calculate radial profiles of azimuthally and vertically averaged magnetic field strength and pitch angle, gas velocity dispersion and scale height, turbulent correlation time and length, and the sizes of supernova remnants for the galaxies M31, M33, M51, and NGC 6946, using input data collected from the literature. Scaling factors are introduced to account for a lack of precision in both theory and observation. Despite the simplicity of our model, its outputs agree fairly well with galaxy properties inferred from observation. Additionally, we find that most of the parameter values are similar between galaxies. We extend the model to predict the magnetic field pitch angles arising from a combination of mean-field dynamo action and the winding up of the random small-scale field owing to the large-scale radial shear. We find their magnitudes to be much smaller than those of the pitch angles measured in polarized radio and far-infrared emission. This suggests that effects not included in our model, such as effects associated with spiral arms, are needed to explain the pitch angle values.}, archive = {J_ApJ}, author = {Rion Glenn Nazareth and Gayathri Santhosh and Luke Chamandy}, doi = {10.3847/1538-4357/ade13e}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {197}, shortjournal = {The Astrophys. J.}, title = {Galactic magnetic fields. II. applying the model to nearby galaxies}, volume = {988}, year = {2025}, }
• (2025). JWST UNCOVERs the optical Size–Stellar mass relation at 4 < z < 8: Rapid growth in the sizes of low-mass galaxies in the first billion years of the universe. ApJ, 988(2), 196. (www)

  @article{ , abstract = {We study the rest-frame optical and ultraviolet (UV) morphology of galaxies in the first billion years of the Universe. Using James Webb Space Telescope data from the UNCOVER and MegaScience surveys targeting the lensing cluster A2744, we present multiband morphological measurements for a sample of 995 galaxies selected using 20-band NIRCam photometry and 35 using NIRSpec Prism spectroscopy over the redshift range of 4 < z < 8. The wavelength-dependent morphology is measured using pysersic by simultaneously modeling the images in six NIRCam wide filters covering the rest-frame UV to optical. The joint modeling technique increases the precision of measured radii by 50%. Galaxies in our sample show a wide range of Sérsic indices, with no systematic difference between optical and UV morphology. We model the size–mass relation in a Bayesian manner using a continuity model to directly fit the redshift evolution while accounting for observational uncertainties. We find the average size of galaxies at \mathrm{log}{M}_{* }/{M}_{\odot }=8.5 grows rapidly, from 400 pc at z = 8 to 830 pc at z = 4. This is faster evolution than expected from power-law scalings of the Hubble parameter or scale factor that describe well previous results at z < 2. This suggests that different and/or much stronger processes affect low-mass systems during the epoch of reionization. The measured logarithmic slope (0.25) and scatter (0.23 dex) are nonevolving. We discuss the remarkable consistency of the slope and scatter over cosmic time in the context of the galaxy–halo connection.}, archive = {J_ApJ}, author = {Tim B. Miller and Katherine A. Suess and David J. Setton and Sedona H. Price and Ivo Labbe and Rachel Bezanson and Gabriel Brammer and Sam E. Cutler and Lukas J. Furtak and Joel Leja and Richard Pan and Bingjie Wang and John R. Weaver and Katherine E. Whitaker and Pratika Dayal and Anna de Graaff and Robert Feldmann and Jenny E. Greene and S. Fujimoto and Michael V. Maseda and Themiya Nanayakkara and Erica J. Nelson and Pieter van Dokkum and Adi Zitrin}, doi = {10.3847/1538-4357/ade438}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {196}, shortjournal = {The Astrophys. J.}, title = {JWST UNCOVERs the optical Size–Stellar mass relation at 4 < z < 8: Rapid growth in the sizes of low-mass galaxies in the first billion years of the universe}, volume = {988}, year = {2025}, }
• (2025). Zones of tayler instability in stars. ApJ, 988(2), 195. (www)

  @article{ , abstract = {The Tayler instability (TI) of toroidal magnetic fields is a candidate mechanism for driving turbulence, angular momentum (AM) transport, and dynamo action in stellar radiative zones. Recently V. A. Skoutnev & A. M. Beloborodov (2024) revisited the linear stability analysis of a toroidal magnetic field in a rotating and stably stratified fluid. In this paper, we extend the analysis to include both thermal and compositional stratification, allowing for general application to stars. We formulate an analytical instability criterion for use as a “toggle switch” in stellar evolution codes. It determines when and where in a star the TI develops with a canonical growth rate as assumed in existing prescriptions for AM transport based on Tayler–Spruit dynamo. We implement such a toggle switch in the MESA stellar evolution code and map out the stability of each mode of the TI on a grid of stellar evolution models. In evolved lower-mass stars, the TI becomes suppressed in the compositionally stratified layer around the hydrogen-burning shell. In higher-mass stars, the TI can be active throughout their radiative zones but at different wavenumbers than previously expected.}, archive = {J_ApJ}, author = {Valentin A. Skoutnev and Andrei M. Beloborodov}, doi = {10.3847/1538-4357/ade547}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {195}, shortjournal = {The Astrophys. J.}, title = {Zones of tayler instability in stars}, volume = {988}, year = {2025}, }
• (2025). Energy spectrum and mass composition of ultra-high-energy cosmic rays originating from relativistic jets of nearby radio galaxies. ApJ, 988(2), 194. (www)

  @article{ , abstract = {Relativistic jets of radio galaxies (RGs) are possible sources of ultra-high-energy cosmic rays (UHECRs). Recent studies combining relativistic hydrodynamic simulations with Monte Carlo particle transport have demonstrated that UHECRs can be accelerated to energies beyond 10 20 eV through shocks, turbulence, and relativistic shear in jet-induced flows of Fanaroff–Riley type RGs. The resulting time-asymptotic UHECR spectrum is well modeled by a double power law with an “extended” exponential cutoff, primarily shaped by relativistic shear acceleration. In this study, we adopt this novel source spectrum and simulate the propagation of UHECRs from nearby RGs using the CRPropa code. We focus on Virgo A (Vir A), Centaurus A (Cen A), Fornax A (For A), and Cygnus A (Cyg A), expected to be the most prominent UHECR sources among RGs. We then analyze the energy spectrum and mass composition of UHECRs arriving at Earth. We find that, due to the extended high-energy tail in the source spectrum, UHECRs from Vir A, which has a higher Lorentz factor, exhibit a higher flux at the highest energies and a lighter mass composition at Earth compared to those from Cen A and For A with lower Lorentz factors. Despite Cyg A having an even higher Lorentz factor, the large distance limits its contribution. With a small number of nearby prominent RGs, our findings suggest that if RGs are the major sources of UHECRs, the energy spectrum and mass composition of observed UHECRs would exhibit hemispheric differences between the Northern and Southern skies at the highest energies.}, archive = {J_ApJ}, author = {Jeongbhin Seo and Dongsu Ryu and Hyesung Kang}, doi = {10.3847/1538-4357/ade678}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {194}, shortjournal = {The Astrophys. J.}, title = {Energy spectrum and mass composition of ultra-high-energy cosmic rays originating from relativistic jets of nearby radio galaxies}, volume = {988}, year = {2025}, }
• (2025). Direct collapse pre-supermassive black hole objects as lyα emitters. ApJ, 988(2), 193. (www)

  @article{ , abstract = {The Direct Collapse scenario to form the supermassive black hole (SMBH) seeds offers the most promising way to explain the origin of quasars at z > 7. Assuming atomic primordial gas, can Ly α photons escape from the central regions of the collapse and serve as a diagnostic for the detection of these pre-SMBH objects? Models of spherical collapse have found these photons to be trapped and destroyed. We use Ly α radiation transfer within the inflow-outflow geometry, based on earlier zoom-in cosmological modeling involving radiation transfer and magnetic forces. Adopting geometry that includes ongoing disk and spherical accretion, and formation of a biconical outflow funnel, we obtain the formation of a dense radiatively driven expanding shell. The Ly α transfer is performed using a Monte Carlo algorithm, accounting for the destruction of Ly α photons and the emergence of two-photon emission. We find that a substantial fraction of Ly α photons can escape through the funnel and calculate the line profiles, their line peak velocity shift, asymmetry, and cuspiness, by varying basic model parameters. The escaping Ly α emission is anisotropic and sensitive to the overall inflow-outflow geometry. The escaping fraction of Ly α radiation exceeds 95% from a z = 10 pre-SMBH object in principle detectable by the JWST NIRSpec in the multiobject spectroscopy mode, during ∼10 4 s for a 10 σ signal-to-noise ratio. Moreover, comparisons with line shapes from high- z galaxies and quasars allow us to separate them from pre-SMBH objects based on the line shape: the pre-SMBH lines show a profound asymmetry and extended red tail.}, archive = {J_ApJ}, author = {Yang Luo and Isaac Shlosman}, doi = {10.3847/1538-4357/ade705}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {193}, shortjournal = {The Astrophys. J.}, title = {Direct collapse pre-supermassive black hole objects as lyα emitters}, volume = {988}, year = {2025}, }
• (2025). Ultraviolet variability in solar-type members of the m67 open cluster. ApJ, 988(2), 192. (www)

  @article{ , abstract = {Solar-type members of the rich, nearly solar-age and solar-metallicity M67 open cluster are systematically investigated for ultraviolet variability. We utilize archival Galaxy Evolution Explorer (GALEX) data, which feature several imaging observation epochs spanning 5 yr. Stars in or suspected of being in binary systems are avoided as well as stars that are blended in GALEX data, leading to a sample of 66 solar-type stars. We assess variability over a variety of timescales that probe flares and longer-term trends that could be due to rotation and activity cycles. We do not find conclusive evidence for variability and determine that solar-type members of M67 do not display >30% near-ultraviolet (NUV) variability over timescales ranging from days to years. Furthermore, within 50 s cadence lightcurves generated for each of the imaging epochs we find no NUV flares that are ≳2× the quiescent stellar NUV emission level; the implied ultraviolet flare rate derived from this study is in mild tension with that derived for stars observed by GALEX in the primary Kepler field. This M67 GALEX study presents one of the most comprehensive ultraviolet data sets currently available for probing continuum emission variability for old Sun-like stars; the planned NASA UVEX mission has the potential to dramatically expand upon this work.}, archive = {J_ApJ}, author = {Carl Melis and Ekamjot Kaire}, doi = {10.3847/1538-4357/addf3b}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {192}, shortjournal = {The Astrophys. J.}, title = {Ultraviolet variability in solar-type members of the m67 open cluster}, volume = {988}, year = {2025}, }
• (2025). A 3D model of the local bubble’s magnetic field: Insights from dust and starlight polarization. ApJ, 988(2), 191. (www)

  @article{ , abstract = {Clustered stellar feedback creates expanding voids in the magnetized interstellar medium known as superbubbles. Although theory suggests that superbubble expansion is influenced by interstellar magnetic fields, direct observational data on 3D superbubble magnetic field geometry is limited. The Sun’s location inside the Local Bubble provides a unique opportunity to infer a superbubble’s 3D magnetic field orientation, under the assumptions that: (I) the Local Bubble’s surface is the primary contributor to plane-of-the-sky polarization observations across much of the sky, and (II) the Local Bubble’s magnetic field is tangent to its dust-traced shell. In this work, we validate these assumptions and construct a model of the Local Bubble’s 3D B -field orientation from Planck 353 GHz polarization observations and a 3D-dust-derived model of the Local Bubble’s shell. We test Assumption I by examining correlations between the Local Bubble’s 3D geometry, dust polarization, and starlight polarization. We find that the Local Bubble likely dominates the polarized signal in the majority of lines of sight. We jointly test Assumptions I and II by applying our reconstruction method to a simulated superbubble, where we successfully reconstruct the 3D magnetic field orientation over the bulk of its surface. Finally, we use our 3D B -field model to infer the initial magnetic field orientation in the solar neighborhood prior to the Local Bubble’s formation, and derive an orientation parallel to the present-day Local Arm of the galaxy. These findings provide new insights into the coevolution of superbubbles and the magnetized interstellar medium.}, archive = {J_ApJ}, author = {Theo J. O’Neill and Alyssa A. Goodman and Juan D. Soler and Catherine Zucker and Jiwon Jesse Han}, doi = {10.3847/1538-4357/ade306}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {191}, shortjournal = {The Astrophys. J.}, title = {A 3D model of the local bubble’s magnetic field: Insights from dust and starlight polarization}, volume = {988}, year = {2025}, }
• (2025). Shaping the milky way: The interplay of mergers and cosmic filaments. ApJ, 988(2), 190. (www)

  @article{ , abstract = {The large-scale morphology of Milky Way (MW)–mass dark matter halos is shaped by two key processes: filamentary accretion from the cosmic web and interactions with massive satellites. Disentangling their contributions is essential for understanding galaxy evolution and constructing accurate mass models of the MW. We analyze the time-dependent structure of MW-mass halos from zoomed cosmological-hydrodynamical simulations by decomposing their mass distribution into spherical harmonic expansions. We find that the dipole and quadrupole moments dominate the gravitational power spectrum, encoding key information about the halo’s shape and its interaction with the cosmic environment. While the dipole reflects transient perturbations from infalling satellites and damps on dynamical timescales, the quadrupole—linked to the halo’s triaxiality—is a persistent feature. We show that the quadrupole’s orientation aligns with the largest filaments, imprinting a long-lived memory on the halo’s morphology even in its inner regions (∼30 kpc). At the virial radius, the quadrupole distortion can reach 1–2 times the spherical density, highlighting the importance of environment in shaping MW-mass halos. Using multichannel singular spectrum analysis, we successfully disentangle the effects of satellite mergers and filamentary accretion on quadrupole. We find that, compared to isolated MW–LMC simulations that typically use a spherical halo, the LMC-mass satellite induces a quadrupolar response that is an order of magnitude larger in our cosmological halo. This highlights the need for models that incorporate the MW’s asymmetry and time evolution, with direct consequences for observable structures such as disk warps, the LMC-induced wake, and stellar tracers—particularly in the era of precision astrometry.}, archive = {J_ApJ}, author = {Arpit Arora and Nicolás Garavito-Camargo and Robyn E. Sanderson and Martin D. Weinberg and Michael S. Petersen and Silvio Varela-Lavin and Facundo A. Gómez and Kathryn V. Johnston and Chervin F. P. Laporte and Nora Shipp and Jason A. S. Hunt and Gurtina Besla and Elise Darragh-Ford and Nondh Panithanpaisal and Kathryne J. Daniel and The EXP collaboration}, doi = {10.3847/1538-4357/ade30d}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {190}, shortjournal = {The Astrophys. J.}, title = {Shaping the milky way: The interplay of mergers and cosmic filaments}, volume = {988}, year = {2025}, }
• (2025). Exploring the evolution of gravitational-wave emitters with efficient emulation: Constraining the origins of binary black holes using normalizing flows. ApJ, 988(2), 189. (www)

  @article{ , abstract = {Binary population synthesis simulations allow detailed modelling of gravitational-wave sources from a variety of formation channels. These population models can be compared to the observed catalogue of merging binaries to infer the uncertain astrophysical input parameters describing binary formation and evolution, as well as the relative rates between various formation pathways. However, it is computationally infeasible to run population synthesis simulations for all variations of uncertain input physics. We demonstrate the use of normalizing flows to emulate population synthesis results and interpolate between astrophysical input parameters. Using current gravitational-wave observations of binary black holes, we use our trained normalizing flows to infer branching ratios between multiple formation channels, and simultaneously infer common-envelope efficiency and natal spins across a continuous parameter range. Given our set of formation channel models, we infer the natal spin to be 0.0{4}_{-0.01}^{+0.04} , and the common-envelope efficiency to be >3.7 at 90% credibility, with the majority of underlying mergers coming from the common-envelope channel. Our framework allows us to measure population synthesis inputs where we do not have simulations, and better constrain the astrophysics underlying current gravitational-wave populations.}, archive = {J_ApJ}, author = {Storm Colloms and Christopher P. L. Berry and John Veitch and Michael Zevin}, doi = {10.3847/1538-4357/ade546}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {189}, shortjournal = {The Astrophys. J.}, title = {Exploring the evolution of gravitational-wave emitters with efficient emulation: Constraining the origins of binary black holes using normalizing flows}, volume = {988}, year = {2025}, }
• (2025). Dynamics of multiphase carbon in the turbulent circumgalactic medium. ApJ, 988(2), 188. (www)

  @article{ , abstract = {The circumgalactic medium (CGM) plays a crucial role in regulating material and energy exchange between galaxies and their environments. The best means of observing this medium is through absorption-line spectroscopy, but we have yet to develop a consistent physical model that fully explains the results. Here we investigate the impact of turbulence and nonequilibrium chemistry on the properties of the CGM, using three-dimensional hydrodynamic simulations that include the impact of an ionizing background. Increasing turbulence enhances small-scale density fluctuations, shifting the kinetic energy spectra from Kolmogorov to Burgers scaling. This is indicative of shock-dominated dissipation, which plays a critical role in driving carbon ionization and shaping the multiphase structure of the medium. At the same time, the presence of background radiation significantly alters the ionization balance, increasing the prevalence of C ii and C iv . Thus, turbulence and the background radiation have complementary roles: turbulence governs the spatial distribution and facilitates the formation of ionized species, whereas the background radiation modifies the overall ionization equilibrium, setting the observed distribution of multiphase carbon.}, archive = {J_ApJ}, author = {Yue Hu and Evan Scannapieco and Edward Buie and Siyao Xu and Samuel T Sebastian and Om Biswal}, doi = {10.3847/1538-4357/ade701}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {188}, shortjournal = {The Astrophys. J.}, title = {Dynamics of multiphase carbon in the turbulent circumgalactic medium}, volume = {988}, year = {2025}, }
• (2025). Exploring the link between extreme coronal line emitters and tidal disruption events. ApJ, 988(2), 187. (www)

  @article{ , abstract = {Galaxies with minimal or no activity from their nucleus can still exhibit significant coronal line (CL) emission, often exceeding the strength of typical narrow emission lines. Many of these CLs require ionization potentials of ≥100 eV, implying the need for intense extreme-ultraviolet and/or soft X-ray flux. Tidal disruption events (TDEs) produced by black holes at galaxy centers are expected to generate such emission lines, yet this link remains underexplored. To evaluate whether CLs are reliable tracers of TDEs, we identified a sample of optical CL galaxies from the Early Data Release of the Dark Energy Spectroscopic Instrument. Our analysis reveals 84 galaxies displaying coronal emission lines among 1.8 million unique targets. Nine sources lie in the active galactic nuclei (AGNs)–starburst composite region and may be AGN-related, so their connection to TDEs remains uncertain. We identified 11 galaxies with spectroscopic coverage in the Sloan Digital Sky Survey, but only 1 exhibits detectable CL variability. We examined the color–magnitude relationship of these extreme coronal line emitters (ECLEs) and found that most are located in the green valley, similar to TDEs. Additionally, our comparison of ECLEs with known TDEs indicates that the stellar mass and star formation rates of ECLE hosts are largely consistent with those of TDE hosts, with many ECLEs also residing within the green valley.}, archive = {J_ApJ}, author = {Weiyu Ding and Weiwen Kong and Jipeng Sui and Yao Yao and Zheyu Lin and Wei-Jian Guo and Hu Zou}, doi = {10.3847/1538-4357/ade70e}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {187}, shortjournal = {The Astrophys. J.}, title = {Exploring the link between extreme coronal line emitters and tidal disruption events}, volume = {988}, year = {2025}, }
• (2025). Evolution of steam worlds: Energetic aspects. ApJ, 988(2), 186. (www)

  @article{ , abstract = {Sub-Neptunes occupy an intriguing region of planetary mass–radius space, where theoretical models of interior structure predict that they could be water-rich, where water is in steam and supercritical state. Such planets are expected to evolve according to the same principles as canonical H 2 –He rich planets, but models that assume a water-dominated atmosphere consistent with the interior have not been developed yet. Here, we present a state-of-the-art structure and evolution model for water-rich sub-Neptunes. Our setup combines an existing atmospheric model that controls the heat loss from the planet, and an interior model that acts as the reservoir of energy. We compute evolutionary tracks of planetary radius over time. We find that planets with pure water envelopes have smaller radii than predicted by previous models, and the change in radius is much slower (within ∼10%). We also find that water in the deep interior is colder than previously suggested, and can transition from plasma state to superionic ice, which can have additional implications for their evolution. We provide a grid of evolutionary tracks that can be used to infer the bulk water content of sub-Neptunes. We compare the bulk water content inferred by this model and other models available in the literature, and find statistically significant differences between models when the uncertainties on measured mass and radius are both smaller than 10%. This study shows the importance of pursuing efforts in the modeling of volatile-rich planets, and how to connect them to observations.}, archive = {J_ApJ}, author = {Artyom Aguichine and Natalie Batalha and Jonathan J. Fortney and Nadine Nettelmann and James E. Owen and Eliza M.-R. Kempton}, doi = {10.3847/1538-4357/add935}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {186}, shortjournal = {The Astrophys. J.}, title = {Evolution of steam worlds: Energetic aspects}, volume = {988}, year = {2025}, }
• (2025). Nuclear spectral energy distributions of luminous infrared galaxies. ApJ, 988(2), 185. (www)

  @article{ , abstract = {We present nuclear (100–150 pc) spectral energy distributions (SEDs) for a sample of 23 nearby luminous infrared galaxies hosting a total of 28 nuclei. We gather aperture photometry from high-resolution X-ray to submillimeter data for each nuclear region localized by Atacama Large Millimeter/submillimeter Array observations of the dust continuum. We model the broadband SEDs using X-CIGALE. Binning the merging systems by interaction class, we find that the active galactic nucleus (AGN) fraction (fraction of AGN infrared luminosity to total infrared luminosity) appears enhanced in the late- and post-merger stages compared to the early-merger stage. Examining the relationship between X-ray emission and infrared emission of the nuclear regions, we find that the infrared emission in the nuclei is dominated by dust and AGNs, with minimal contribution from stars. We also find that nuclear regions have higher X-ray hardness ratios than the host galaxies globally among both the AGN and non-AGN population. We highlight the similarities and differences in the SEDs of dual nuclei in five closely separated late-stage merging systems: Arp 220 ( d nuc ∼ 0.5 kpc), NGC 6240 ( d nuc ∼ 1 kpc), IRAS 07251−0248 ( d nuc ∼ 2 kpc), IRAS F12112+0305 ( d nuc ∼ 4 kpc), and IRAS F14348+1447 ( d nuc ∼ 6 kpc). The SEDs for these resolved pairs are distinct, suggesting that the AGN state is much more susceptible to the stellar and dust content within the immediate circumnuclear (<150 pc) environment than to the host’s global infrared luminosity or merger stage.}, archive = {J_ApJ}, author = {Tianmu Gao and Vivian U and Connor W. Auge and Yiqing Song and Sean T. Linden and Kazushi Iwasawa and Alessandro Peca and George C. Privon and David B. Sanders and Núria Torres-Albà and Loreto Barcos-Muñoz and James Agostino and Anne M. Medling}, doi = {10.3847/1538-4357/add0b2}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {185}, shortjournal = {The Astrophys. J.}, title = {Nuclear spectral energy distributions of luminous infrared galaxies}, volume = {988}, year = {2025}, }
• (2025). Thermonuclear supernova explosion criteria for direct and indirect collisions of CO white dwarfs: A study of the impact-parameter threshold for detonation. ApJ, 988(2), 184. (www)

  @article{ , abstract = {The physical collisions of two white dwarfs (WDs; i.e., not slow mergers) have been shown to produce Type Ia–like supernova (SN) explosions. Most studies of WD collisions have focused on zero impact-parameter (direct) collisions, which can also be studied in 2D. However, the vast majority of WD collisions arising from any evolutionary channel suggested to date are expected to be indirect, i.e., have a nonnegligible impact parameter upon collision. Here, we use one of the highest-resolution 3D simulations to date (making use of the AREPO code) in order to explore both direct and indirect collisions and the conditions in which they give rise to a detonation and the production of a luminous SN. Using our simulations, we find a detonation criterion that can provide the critical impact parameter for an explosion to occur, depending on the density profile of the colliding WDs, their composition, and their collision velocities. We find that the initial velocity has a significant impact on the amount of 56 Ni production from the explosion. Furthermore, the production of the 56 Ni also depends on numerical modeling aspects.}, archive = {J_ApJ}, author = {Hila Glanz and Hagai B. Perets and Ruediger Pakmor}, doi = {10.3847/1538-4357/ade146}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {184}, shortjournal = {The Astrophys. J.}, title = {Thermonuclear supernova explosion criteria for direct and indirect collisions of CO white dwarfs: A study of the impact-parameter threshold for detonation}, volume = {988}, year = {2025}, }
• (2025). Fundamental parameters for central stars of 103 infrared bow shock nebulae. ApJ, 988(2), 183. (www)

  @article{ , abstract = {Stellar bow shock nebulae are arcuate shock fronts formed by the interaction of radiation-driven stellar winds and the relative motion of the ambient interstellar material. Stellar bow shock nebulae provide a promising means to measure wind-driven mass loss, independent of other established methods. In this work, we characterize the stellar sources at the center of bow shock nebulae drawn from all-sky catalogs of 24 μ m–selected nebulae. We obtain new, low-resolution blue optical spectra for 104 stars and measure stellar parameters temperature T eff , surface gravity {\mathrm{log}}\,g , and projected rotational broadening v\sin i . We perform additional photometric analysis to measure stellar radius R * , luminosity L * , and visual-band extinction A V . All but one of our targets are O and early B stars, with temperatures ranging from T = 16.5 to 46.8 kK, gravities from {\mathrm{log}}\,g= 2.57 to 4.60, and v\sin i from <100 to 400 km s −1 . With the exception of rapid rotator ζ Oph, bow shock stars do not rotate at or near critical velocities. At least 60 of 103 (60%) OB bow shock stars are binaries, consistent with the multiplicity fraction of other OB samples. The sample shows a runaway fraction of 23%, with 19 stars having v 2D ≥ 25 km s −1 . Of the 19 runaways, at least 15 (≥79%) are binaries, favoring dynamical ejection over the binary supernova channel for producing runaways. We provide a comprehensive census of stellar parameters for bow shock stars, useful as a foundation for determining the mass-loss rates for OB-type stars—one of the single most critical factors in stellar evolution governing the production of neutron stars and black holes.}, archive = {J_ApJ}, author = {Nikhil Patten and Henry A. Kobulnicky and Matthew S. Povich and Angelica S. Whisnant and Sydney Andrews and Alexandra Boone and Srujan Dandu and Naomi Jones and S. Nick Justice and Dylan Hope and Alexander Larsen and Ryan McCrory and Julia Meredith and Maria Renee Meza and Alexandra C. Rosenthal and William Salazar and Alexander R. Sterling and Noshin Yesmin and Daniel A. Dale}, doi = {10.3847/1538-4357/ade22f}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {183}, shortjournal = {The Astrophys. J.}, title = {Fundamental parameters for central stars of 103 infrared bow shock nebulae}, volume = {988}, year = {2025}, }
• (2025). A large-scale ring galaxy at z = 2.2 revealed by JWST/NIRCam: Kinematic observations and analytical modelling. ApJ, 988(2), 182. (www)

  @article{ , abstract = {A unique galaxy at z = 2.2, zC406690, has a striking clumpy large-scale ring structure that persists from rest-frame UV to near-infrared, yet has an ordered rotation and lies on the star formation main sequence. We combine new JWST/NIRCam and Atacama Large Millimeter/submillimeter Array (ALMA) band 4 observations, together with previous Very Large Telescope/SINFONI integral field spectroscopy and Hubble Space Telescope imaging to reexamine its nature. The high-resolution H α kinematics is best fitted if the mass is distributed within a ring with total mass M ring ≈ 2 × 10 10 M ⊙ and radius R ring = 4.6 kpc, together with a central undetected mass component (e.g., a “bulge”) with a dynamical mass of M bulge = 8 × 10 10 M ⊙ . We also consider a purely flux-emitting ring superposed over a faint exponential disk, or a highly “cuspy” dark matter halo, both disfavored against a massive ring model. The low-resolution CO(4–3) line and 142 GHz continuum emission imply total molecular and dust gas masses of M mol,gas = 7.1 × 10 10 M ⊙ and M dust = 3 × 10 8 M ⊙ , respectively, over the entire galaxy, giving a dust-to-gas ratio of 0.7%. We estimate that roughly half the gas and dust mass lie inside the ring, and that ∼10% of the total dust is in a foreground screen that attenuates the stellar light of the bulge in the rest-frame UV to near-infrared. Sensitive high-resolution ALMA observations will be essential to confirm this scenario and study the gas and dust distribution.}, archive = {J_ApJ}, author = {A. Nestor Shachar and A. Sternberg and R. Genzel and D. Liu and S. H. Price and C. Pulsoni and L. J. Tacconi and R. Herrera-Camus and N. M. Förster Schreiber and A. Burkert and J. B. Jolly and D. Lutz and S. Wuyts and C. Barfety and Y. Cao and J. Chen and R. Davies and F. Eisenhauer and J. M. Espejo Salcedo and L. L. Lee and M. Lee and T. Naab and S. Pastras and T. T. Shimizu and E. Sturm and G. Tozzi and H. Übler}, doi = {10.3847/1538-4357/ade2d0}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {182}, shortjournal = {The Astrophys. J.}, title = {A large-scale ring galaxy at z = 2.2 revealed by JWST/NIRCam: Kinematic observations and analytical modelling}, volume = {988}, year = {2025}, }
• (2025). Multispacecraft observations of the 27 day periodicity in galactic protons from 2018 to 2019. ApJ, 988(2), 181. (www)

  @article{ , abstract = {Galactic cosmic-ray (GCR) intensities exhibit recurrent variations caused by their passage through plasma interaction regions corotating with the Sun, with the ∼27 day periodicity being the most prominent one. Data collected by the High-Energy Particle Detector (HEPD-01) on board the China Seismo-Electromagnetic Satellite in Low-Earth Orbit have been used to derive daily proton fluxes from 2018 to 2019 August, in the energy range between ∼55 and ∼200 MeV. Daily fluxes from HEPD-01 have been analyzed along with proton fluxes measured during the same period by ERNE and EPHIN, on board the SOHO spacecraft, and by AMS-02, on board the International Space Station. Using a time-frequency analysis, we confirm a slight energy dependence for the power of the ∼27 day variation as a function of time, with the periodicity maximum occurring earlier for HEPD-01 than for high-energy data from AMS-02. Additionally, as already obtained in previous studies, the rigidity dependence of the amplitude of the aforementioned GCR variation cannot be described by the same power law at both low and high energies, as a consequence of different physical mechanisms playing roles at different rigidity ranges. HEPD-01 GCR measurements cover the energy range from tens to a few hundreds of MeV, which is not accessible to existing detectors (EPHIN and ERNE covering from a few MeV up to tens or a hundred MeV, respectively, and AMS-02 in the GeV–TeV energy range), providing important information for understanding GCR periodicities.}, archive = {J_ApJ}, author = {S. Amoroso and M. Babu and S. Bartocci and R. Battiston and S. Beolè and W. J. Burger and D. Campana and P. Cipollone and L. Conti and A. Contin and M. Cristoforetti and C. De Donato and C. De Santis and A. Di Luca and F. M. Follega and G. Gebbia and R. Iuppa and A. Lega and M. Lolli and M. Martucci and G. Masciantonio and M. Mergè and M. Mese and C. Neubüser and R. Nicolaidis and F. Nozzoli and A. Oliva and G. Osteria and F. Palma and B. Panico and F. Perfetto and A. Perinelli and P. Picozza and S. Pietroni and M. Pozzato and E. Ricci and L. Ricci and M. Ricci and S. B. Ricciarini and Z. Sahnoun and U. Savino and V. Scotti and M. Sorbara and A. Sotgiu and R. Sparvoli and P. Ubertini and V. Vilona and S. Zoffoli and P. Zuccon and M. Boezio and R. Munini and O. P. M. Aslam and X. Luo and D. C. Ndiitwani and M. D. Ngobeni and M. Piersanti and M. S. Potgieter and I. I. Ramokgaba}, doi = {10.3847/1538-4357/ade2e2}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {181}, shortjournal = {The Astrophys. J.}, title = {Multispacecraft observations of the 27 day periodicity in galactic protons from 2018 to 2019}, volume = {988}, year = {2025}, }
• (2025). Understanding the complex morphology of a coronal mass ejection: Multiview analysis and numerical modeling. ApJ, 988(2), 180. (www)

  @article{ , abstract = {Although all coronal mass ejections (CMEs) that propagate into the heliosphere should contain a magnetic flux rope (MFR) component, the majority do not exhibit the expected white-light MFR morphology of a leading edge plus a cavity. This different appearance could be the result of distortion of the internal magnetic structure, merging with other structures, or simply projection effects. These factors complicate the interpretation of CMEs. This complexity is exemplified by a CME observed on 2022 March 28. The event originated from a single eruption, evolving as a textbook CME in the low corona but appearing as a complex two-MFR structure in the white-light observations. Why? To answer this question, we performed a multiview data and modeling analysis to describe the CME coronal evolution. The thermodynamic magnetohydrodynamic model, CORHEL-CME, helps reveal the magnetic configuration of this CME and also reveals that the ambient field plays a crucial role in shaping the complex structure of the CME during early evolution. Our research underscores the importance of integrating multiview observations with physics-based models to gain a deeper insight into the development of complex CMEs.}, archive = {J_ApJ}, author = {Cecilia Mac Cormack and Abril Sahade and Angelos Vourlidas and Phillip Hess and Robin Colaninno and Teresa Nieves-Chinchilla}, doi = {10.3847/1538-4357/ade311}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {180}, shortjournal = {The Astrophys. J.}, title = {Understanding the complex morphology of a coronal mass ejection: Multiview analysis and numerical modeling}, volume = {988}, year = {2025}, }
• (2025). Evidence that mass loss on the red giant branch decreases with metallicity. ApJ, 988(2), 179. (www)

  @article{ , abstract = {Mass loss on the red giant branch (RGB) influences stellar evolution, properties of stellar populations, and Galactic chemical enrichment, yet remains poorly constrained observationally. Current models provide limited insight into how stellar properties, particularly how metallicity and mass, affect RGB mass loss. Here, I introduce a new observational approach that uses the age–velocity-dispersion relation and the lower-mass boundary of red giants as precise evolutionary markers. These markers, informed by Galactic evolution, allow us to construct observational isochrones for field stars. By comparing masses of RGB stars and red clump (RC) stars at the same age in the Kepler sample, I derive empirical measurements of integrated RGB mass loss at several points in age and metallicity. Combining these new observational measurements with open-cluster studies, I showed that the integrated mass loss on the RGB decreases with metallicity, and may also decrease with stellar mass. The average mass-loss rate, which accounts for RGB lifetimes and the initial mass differences between RGB and RC stars at the same age, also shows a similar trend. These findings challenge current mass-loss prescriptions widely adopted in stellar evolutionary models, since none of them is able to produce the observed mass-loss trend without widely adjusting free parameters. This highlights an urgent need to revise mechanisms that govern RGB mass loss.}, archive = {J_ApJ}, author = {Yaguang Li}, doi = {10.3847/1538-4357/ade3c7}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {179}, shortjournal = {The Astrophys. J.}, title = {Evidence that mass loss on the red giant branch decreases with metallicity}, volume = {988}, year = {2025}, }
• (2025). Constraining the z ∼ 1 initial mass function with HST and JWST lensed stars in MACS j0416.1−2403. ApJ, 988(2), 178. (www)

  @article{ , abstract = {Our understanding of galaxy properties and evolution is contingent on knowing the initial mass function (IMF), and yet to date the IMF is constrained only to local galaxies. Individual stars are now becoming routinely detected at cosmological distances, where luminous stars such as supergiants in background galaxies strongly lensed by galaxy clusters are temporarily further magnified by huge factors (up to 10 4 ) by intracluster stars, thus being detected as transients. The detection rate of these events depends on the abundance of luminous stars in the background galaxy and is thus sensitive to the IMF and the star formation history (SFH), especially for the blue supergiants detected as transients in the rest-frame ultraviolet/optical filters. As a proof of concept, we use simple SFH and IMF models constrained by spectral energy distributions (SEDs) to see how well we can predict the Hubble Space Telescope and James Webb Space Telescope transient detection rate in a lensed arc dubbed “Spock” ( z = 1.0054). We find that demanding a simultaneous fit of the SED and the transient detection rate places constraints on the IMF, independent of the assumed simple SFH model. We conclude that our likelihood analysis indicates that the data definitively prefers the “Spock” galaxy to have a Salpeter IMF ( α = 2.35) rather than a top-heavy IMF ( α = 1)—which is thought to be the case in the early universe—with no clear excess of supergiants above the standard IMF.}, archive = {J_ApJ}, author = {Sung Kei Li and Jose M. Diego and Ashish K. Meena and Jeremy Lim and Leo W. H. Fung and Arsen Levitskiy and James Nianias and Jose M. Palencia and Hayley Williams and Jiashuo Zhang and Alfred Amruth and Thomas J. Broadhurst and WenLei Chen and Alexei V. Filippenko and Patrick L. Kelly and Anton M. Koekemoer and Derek Perera and Bangzheng Sun and Liliya L. R. Williams and Rogier A. Windhorst and Haojin Yan and Adi Zitrin}, doi = {10.3847/1538-4357/ade4bd}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {178}, shortjournal = {The Astrophys. J.}, title = {Constraining the z ∼ 1 initial mass function with HST and JWST lensed stars in MACS j0416.1−2403}, volume = {988}, year = {2025}, }
• (2025). Refined constraints on the hubble constant from localized fast radio bursts with assessment of systematic effects. ApJ, 988(2), 177. (www)

  @article{ , abstract = {The dispersion measure–redshift relation of fast radio bursts (FRBs) provides a valuable cosmological probe for constraining the Hubble constant, offering an independent measurement that could help resolve the ongoing Hubble tension. In this paper, we begin with a sample of 117 localized FRBs and use 95 of them to constrain H 0 to 71.2{8}_{-2.08}^{+1.90} km s −1 Mpc −1 within the standard Lambda cold dark matter model. The resulting statistical uncertainty is below 2.8%, improving previous FRB-based measurements and highlighting the promise of larger future samples. Beyond statistical improvements, we note that different parameter choices have been adopted in previous studies and some results show discrepancies in H 0 . To address this issue, we perform a systematic assessment of modeling uncertainties that can affect the inferred value of H 0 , including models of the Galactic electron density, the contribution of the Galactic halo, outliers such as FRB 20190520B located in extreme environments, and the other parameter selections. We also discuss possible approaches to mitigate these sources of uncertainty, emphasizing both the challenges and prospects of using FRBs as reliable cosmological tools.}, archive = {J_ApJ}, author = {Chenyuan Xu and Yi Feng and Jiaying Xu}, doi = {10.3847/1538-4357/ade5b5}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {177}, shortjournal = {The Astrophys. J.}, title = {Refined constraints on the hubble constant from localized fast radio bursts with assessment of systematic effects}, volume = {988}, year = {2025}, }
• (2025). Distances of supernova remnants associated with neutron stars in the galaxy. ApJ, 988(2), 176. (www)

  @article{ , abstract = {Accurate distance measurements to supernova remnants (SNRs) are essential for determining their physical parameters, such as size, age, and explosion energy, and for constraining the properties of associated neutron stars (NSs). We present an extinction–distance method that combines precise Gaia DR3 photometry, parallax, and stellar parameters from the SHBoost catalog to homogeneously construct extinction–distance profiles for 44 NS-associated Galactic SNRs. Applying a statistical model, we identify clear extinction jumps along each sightline, corresponding to probable SNR distances. We classify the results into three reliability levels (A, B, and C), primarily based on comparisons with previously reported kinematic distances, supplemented by independent estimates from other methods. Our results show that the majority of reliable distances (17 Level A and 8 Level B) are located within 5 kpc, predominantly in the Local Arm. This study presents an independent and effective method for determining distances to SNRs, particularly for those with small angular sizes or located in the second and third Galactic quadrants. Although the current method is limited to within 5 kpc due to the precision constraints of Gaia parallax and photometry, the upcoming Gaia DR4 release, combined with complementary infrared data, will extend its applicability to more distant and heavily obscured SNRs and help resolve kinematic distance ambiguities.}, archive = {J_ApJ}, author = {Xiaohan Chen and Shu Wang and Xiaodian Chen}, doi = {10.3847/1538-4357/ade688}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {176}, shortjournal = {The Astrophys. J.}, title = {Distances of supernova remnants associated with neutron stars in the galaxy}, volume = {988}, year = {2025}, }
• (2025). Polarization position angle swing and the rotating vector model of repeating fast radio bursts. ApJ, 988(2), 175. (www)

  @article{ , abstract = {Fast radio bursts (FRBs), typically highly polarized, usually have a nearly constant polarization position angle (PA) during each burst. Some bursts show significant PA variations, and one of them was claimed to have a PA variation pattern consistent with the prediction of the rotating vector model (RVM) commonly adopted to fit the PA variations in radio pulsars. We systematically study the PA evolution pattern of 1727 bursts from three active repeating FRB sources monitored by the Five-hundred-meter Aperture Spherical Radio Telescope. We identify 46 bursts whose PA variations are fully consistent with the RVM. However, the inferred geometrical parameters and rotation periods derived from these RVM fittings are inconsistent from each other. This suggests that the magnetosphere of the FRB central engine is constantly distorted by the FRB emitter and the magnetic configuration is dynamically evolving.}, archive = {J_ApJ}, author = {Xiaohui Liu and Heng Xu and Jiarui Niu and Yongkun Zhang and Jinchen Jiang and Dejiang Zhou and Jinlin Han and Weiwei Zhu and Kejia Lee and Di Li and Wei-Yang Wang and Bing Zhang and Xuelei Chen and Jia-Wei Luo and Rui Luo and Chenhui Niu and Yuanhong Qu and Bojun Wang and Fayin Wang and Pei Wang and Tiancong Wang and Qin Wu and Ziwei Wu and Jiangwei Xu and Yuan-Pei Yang and Jun-Shuo Zhang}, doi = {10.3847/1538-4357/ade689}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {175}, shortjournal = {The Astrophys. J.}, title = {Polarization position angle swing and the rotating vector model of repeating fast radio bursts}, volume = {988}, year = {2025}, }
• (2025). High-resolution observations of a flare associated with a partial filament eruption on 2023 april 21. ApJ, 988(2), 174. (www)

  @article{ , abstract = {We investigate an eruptive M-class flare on 2023 April 21 (SOL2023-04-21T18:12) with observations from the Solar Dynamics Observatory and the Chinese H α Solar Explorer. We discuss two stages of energy release, the preflare activity and the eruptive flare. The preflare phase features some brightening of the lower atmosphere, the rising motion of filament materials, and a brightening ribbon structure. We suggest that low-altitude magnetic reconnection triggers the eruptive activity. The reconnection between the ambient loops and continuously rising thread-like structures produced the well-formed parallel-ribbon flare. In the main flare phase, the filament experienced a partial eruption with significant plasma motion in the constrained part. We propose a double-decker filament structure based on the multiwavelength observations and analysis of the magnetic field.}, archive = {J_ApJ}, author = {Ke Yu and Jin-Han Guo and Yuandeng Shen and Xinping Zhou and Yihua Li and Ye Qiu and Zhining Qu}, doi = {10.3847/1538-4357/ade801}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {174}, shortjournal = {The Astrophys. J.}, title = {High-resolution observations of a flare associated with a partial filament eruption on 2023 april 21}, volume = {988}, year = {2025}, }
• (2025). Gaussian mixtures in solar wind plasma turbulence. ApJ, 988(2), 173. (www)

  @article{ , abstract = {Based on previous analyses of data from a fleet of space exploration missions, we argue that plasma fluctuations in the turbulent solar wind are consistently described by normal variance mixtures on a broad range of scales encompassing the inertial and kinetic scales. In the inertial range, the normal variance mixture distributions are derived from conditioning the Elsässer field increments either on fluctuations of the energy transfer rate or on fluctuations of the singularity strength. The two kinds of description can be linked to each other via bridging relations. An exact analytical expression for the even-order structure functions is obtained from a normal inverse Gaussian fit, accurate from inertial to dissipative scales in the plasma. The self-similar kappa distributions describing the kinetic scales result from an inverse χ 2 distribution of the variance in the Gaussian mixture model.}, archive = {J_ApJ}, author = {N. H. Bian and Gang Li}, doi = {10.3847/1538-4357/ade80b}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {173}, shortjournal = {The Astrophys. J.}, title = {Gaussian mixtures in solar wind plasma turbulence}, volume = {988}, year = {2025}, }
• (2025). The centre of attention: A powerful radio galaxy pinpoints a near-infrared-dark protocluster at z ∼ 3.9. ApJ, 988(2), 172. (www)

  @article{ , abstract = {We report the discovery of a z ∼ 3.9 protocluster identified from Atacama Large Millimeter/submillimeter Array Band 3 spectral scans of a bright radio source selected from the Galactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey. Extended CO(4–3) and [C I ] ( 3 P 1 → 3 P 0 ) line emission was detected in GLEAM J005332−325630 confirming it to be a z = 3.879 powerful radio galaxy with luminosity L 500 MHz = 1.3 × 10 28 W Hz −1 . This source is part of a sample of candidate high-redshift radio galaxies with bright radio fluxes, S 150 MHz > 0.1 Jy, but host galaxies with K s (AB) ≳ 23 mag. The molecular gas associated with the radio galaxy host has two kinematically separate components, likely infalling and indicative of a recent interaction or merger with another galaxy. One 100 GHz continuum source ∼120 pkpc away is found to have both CO(4–3) and [C I ] ( 3 P 1 → 3 P 0 ) emission lines and a further five protocluster members are identified from CO(4–3) emission alone, all at a similar redshift (Δ v < 700 km s −1 ) and within a radius of 1.^{\prime} 1 . Using photometry from the High Acuity Widefield K -band Imager K s band and the Dark Energy Survey g , r , i , z , and Y bands, we find this protocluster harbours a rare, optically dark, very massive M * ∼ 10 12 M ⊙ galaxy. Comparisons with the TNG300 cosmological simulation puts this galaxy in a dark matter (DM) halo of M DM ∼ 3 × 10 13 M ⊙ , which will evolve into a Coma-like DM halo ( M DM ∼ 10 15 M ⊙ ) by the present day.}, archive = {J_ApJ}, author = {A. J. Hedge and N. Seymour and J. W. Broderick and A. Gupta and J. Afonso and L. Ighina and M. Lehnert and G. Noirot and S. Shabala and D. Stern and R. J. Turner}, doi = {10.3847/1538-4357/addf2e}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {172}, shortjournal = {The Astrophys. J.}, title = {The centre of attention: A powerful radio galaxy pinpoints a near-infrared-dark protocluster at z ∼ 3.9}, volume = {988}, year = {2025}, }
• (2025). GNHeII j1236+6215: A he II λ1640 emitting and potentially LyC leaking galaxy at z = 2.9803 unveiled through JWST and keck observations. ApJ, 988(2), 171. (www)

  @article{ , abstract = {He II λ 1640 emission in galaxies indicates the presence of sources that produce extreme ionizing photons. Here we report the discovery of a He II λ 1640 emitting galaxy, GNHeII J1236+6215, at z =  2.9803 in the GOODS-north field. We use photometry in 17 wave bands from near-UV to infrared to characterize the galaxy spectral energy distribution (SED) and combine Keck Low-resolution Imaging Spectrometer and JWST NIRSpec spectra to identify 15 emission lines including He II λ 1640. We infer that the He + ionization in the galaxy could be driven by small pockets of young Population III stars or low-metallicity very massive stars rather than active galactic nuclei or metal-rich Wolf–Rayet stars. The galaxy has a highly ionized interstellar medium (ISM) ([O III ]5007/[O II ]3727 = 7.28 ± 0.11, [S III ]/[S II ] = 1.97 ± 0.48, and detected Ly α , H α , H β , H γ lines), little reddening by dust ( E ( B − V ) = 0.04 ± 0.12), low metallicity (12 + log(O/H) = 7.85 ± 0.22), and high star formation rate (SFR SED = 12.2 ± 2.0 M ⊙ yr −1 ). In addition to these ISM conditions, we also notice a significant [S II ] deficiency ([S II ]6718,6732/H α = 0.08 ± 0.02, Δ[S II ] = −0.12), which may indicate the presence of density-bounded optically thin H II regions that, combined with the low-dust extinction, favor leaking of ionizing Lyman continuum photons. Our best-fit SED model also infers a high nebular ionization (log U = −2.0) and a low stellar mass M = 7.8 ± 3.1 × 10 8 M ⊙ . This discovery not only adds one important object to the known sample of high-redshift He II emitters but also highlights a potential connection between He + ionization and favorable ISM conditions for the leakage of ionizing photons from galaxies.}, archive = {J_ApJ}, author = {Chayan Mondal and Kanak Saha and Anshuman Borgohain and Brent M. Smith and Rogier A. Windhorst and Naveen Reddy and Chian-Chou Chen and Keiichi Umetsu and Rolf A. Jansen}, doi = {10.3847/1538-4357/ade2cd}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {171}, shortjournal = {The Astrophys. J.}, title = {GNHeII j1236+6215: A he II λ1640 emitting and potentially LyC leaking galaxy at z = 2.9803 unveiled through JWST and keck observations}, volume = {988}, year = {2025}, }
• (2025). Low-energy measurement of the 86Kr(α, n)89Sr reaction cross section and its impact on weak R-process nucleosynthesis. ApJ, 988(2), 170. (www)

  @article{ , abstract = {The cross section of the 86 Kr( α , n ) 89 Sr reaction was measured at low energies using the activation technique via the detection of the β − emission from the residual 89 Sr nuclei. The theoretical analysis of the measured cross sections shows that the new data can be well described in the statistical model using several recent α -nucleus potentials. The resulting astrophysical reaction rate has small uncertainties between about 15% at higher temperatures and up to a factor of 2 at low temperatures. Using this new reaction rate of the 86 Kr( α , n ) 89 Sr reaction for the nucleosynthesis in neutrino-driven outflows in core-collapse supernovae leads to well-constrained production ratios for the nuclei slightly above krypton ( Z = 36) like Sr/Zr, Y/Zr, and Mo/Zr. A comparison to observational ratios in metal-poor stars allows to constrain the astrophysical conditions for this weak r -process.}, archive = {J_ApJ}, author = {G. G. Kiss and S. R. Kovács and T. N. Szegedi and P. Mohr and F. Montes and A. Arcones and Á. Tóth and A. Németh and E. Szilágyi and M. Kumar Pal and M. Braun and Z. Halász and Z. Elekes and Gy. Gyürky and T. Szücs}, doi = {10.3847/1538-4357/ade4c9}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {170}, shortjournal = {The Astrophys. J.}, title = {Low-energy measurement of the 86Kr(α, n)89Sr reaction cross section and its impact on weak R-process nucleosynthesis}, volume = {988}, year = {2025}, }
• (2025). The gravity collective: A comprehensive analysis of the electromagnetic search for the binary neutron star merger GW190425. ApJ, 988(2), 169. (www)

  @article{ , abstract = {We present an ultraviolet to infrared search for the electromagnetic (EM) counterpart to GW190425, the second ever binary neutron star merger discovered by the LIGO-Virgo-KAGRA Collaboration. GW190425 was more distant and had a larger localization area than GW170817, so we use a new tool, Teglon , to redistribute the GW190425 localization probability in the context of galaxy catalogs within the final localization volume. We derive a 90th percentile area of 6688 deg 2 , a ∼1.5× improvement relative to the LIGO/Virgo map, and show how Teglon provides an order-of-magnitude boost to the search efficiency of small (≤1 deg 2 ) field-of-view instruments. We combine our data with a large, publicly reported imaging data set, covering 9078.59 deg 2 of unique area and 48.13% of the LIGO/Virgo-assigned localization probability, to calculate the most comprehensive kilonova (KN), short gamma-ray burst (sGRB) afterglow, and model-independent constraints on the EM emission from a hypothetical counterpart to GW190425 to date under the assumption that no counterpart was found in these data. If the counterpart were similar to AT 2017gfo, there would be a 28.4% chance of it being detected in the combined data set. We are relatively insensitive to an on-axis sGRB, and rule out a generic transient with a similar peak luminosity and decline rate as AT 2017gfo to 30% confidence. Finally, across our new imaging and publicly reported data, we find 28 candidate optical counterparts that we cannot rule out as being associated with GW190425, finding that four such counterparts discovered within the localization volume and within 5 days of merger exhibit luminosities consistent with a KN.}, archive = {J_ApJ}, author = {D. A. Coulter and C. D. Kilpatrick and D. O. Jones and R. J. Foley and J. Anais Vilchez and I. Arcavi and K. E. Clever and G. Dimitriadis and A. V. Filippenko and N. Muñoz-Elgueta and A. L. Piro and P. J. Quiñonez and G. S. Rahman and C. Rojas-Bravo and M. R. Siebert and H. E. Stacey and J. J. Swift and W. Zheng and J. S. Bloom and M. J. Bustamante-Rosell and K. W. Davis and J. Kutcka and P. Macias and P. McGill and E. Ramirez-Ruiz and K. Siellez and S. Tinyanont and S. B. Cenko and M. R. Drout and R. Hausen and D. Andrew Howell and W. V. Jacobson-Galán and D. Kasen and C. McCully and A. Rest and K. Taggart and S. Valenti}, doi = {10.3847/1538-4357/ade0b3}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {169}, shortjournal = {The Astrophys. J.}, title = {The gravity collective: A comprehensive analysis of the electromagnetic search for the binary neutron star merger GW190425}, volume = {988}, year = {2025}, }
• (2025). Long-term astrometric monitoring of the galactic center magnetar PSR j1745−2900. ApJ, 988(2), 168. (www)

  @article{ , abstract = {We present new astrometric observations of the Galactic center magnetar PSR J1745−2900 with the Very Long Baseline Array. Combined with previously published measurements in 10 epochs that spanned 477 days, the complete data set consists of 25 epochs and 41 independent measurements that span 1984 days. These data constrain the proper motion to an accuracy of ≲2% and set an upper limit on the absolute value of the magnetar’s acceleration of ≲(0.4, 0.2) mas yr −2 in the two celestial coordinates, consistent with the maximum value of ∼0.03 mas yr −2 expected for an orbit around Sgr A*. Future measurements have the potential to detect the acceleration of PSR J1745−2900 due to Sgr A* should PSR J1745−2900 rebrighten. We consider several potential sources of systematic variations in the astrometric residuals after fitting for standard parameters, including refractive wander, changes in the structure of Sgr A*, and the presence of an unseen binary companion. While a stellar companion model can be fit to the astrometric data, pulse period measurements are inconsistent with that model. No changes in the apparent image size of the magnetar were detected over the duration of these observations, indicating a lack of change in the properties of the line-of-sight scattering during this period. We also show that the upper limit to the mean core shift of Sgr A* is consistent with expectations for a compact jet or symmetric accretion flow.}, archive = {J_ApJ}, author = {Geoffrey C. Bower and Adam T. Deller and Paul B. Demorest and Jason Dexter and Andreas Brunthaler and Gregory Desvignes and Ralph P. Eatough and Heino Falcke and Ciriaco Goddi and Michael Kramer and F. Yusef-Zadeh}, doi = {10.3847/1538-4357/ade0be}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {168}, shortjournal = {The Astrophys. J.}, title = {Long-term astrometric monitoring of the galactic center magnetar PSR j1745−2900}, volume = {988}, year = {2025}, }
• (2025). Detecting stellar coronal mass ejections via coronal dimming in the extreme ultraviolet. ApJ, 988(2), 167. (www)

  @article{ , abstract = {Stellar flares and coronal mass ejections (CMEs) can strip planetary atmospheres, reducing the potential habitability of terrestrial planets. While flares have been observed for decades, stellar CMEs remain elusive. Extreme-ultraviolet (EUV) emissions are sensitive to both flares and CME-induced coronal dimming. We assess the detectability of stellar CME-induced EUV dimming events by adapting a known “Sun-as-a-star” dimming technique—validated by the Solar Dynamics Observatory’s EUV Variability Experiment (EVE)—to stellar conditions. We adapt the solar data to reflect a range of stellar intensities, accounting for intrinsic brightness, distance, and interstellar medium (ISM) attenuation. We generate synthetic light curves for two different missions: the legacy EUV Explorer (EUVE) and the proposed ESCAPE mission. Our results indicate that dimming detections are well within reach. EUVE’s broadband imager was capable of detecting stellar CMEs—albeit with limited spectral (temperature) resolution—but that was not part of the observing plan. EUVE’s spectroscopic survey lacked sufficient sensitivity for CME detections. Optimizing modern instrument design for this task would make the observation fully feasible. In this work, we present a tool to explore the stellar-CME detection parameter space. Our tool shows that with an instrument with performance similar to ESCAPE, setting a 600 s integration period, and integrating the spectra into bands, any star with a X-ray flux ≥2.51 × 10 −12 erg s −1 cm −2 should have a ≥3 σ detection even for a modest few-percent dimming profile, regardless of ISM attenuation. Such measurements would be crucial for understanding the space weather environments of exoplanet host stars and, ultimately, for evaluating planetary habitability.}, archive = {J_ApJ}, author = {James Paul Mason and Allison Youngblood and Kevin France and Astrid M. Veronig and Meng Jin}, doi = {10.3847/1538-4357/ade4bc}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {167}, shortjournal = {The Astrophys. J.}, title = {Detecting stellar coronal mass ejections via coronal dimming in the extreme ultraviolet}, volume = {988}, year = {2025}, }
• (2025). Discovery and multiwavelength analysis of a new dissociative galaxy cluster merger: The champagne cluster. ApJ, 988(2), 166. (www)

  @article{ , abstract = {We report the discovery of a new binary galaxy cluster merger, the Champagne Cluster (RM J130558.9+263048.4), using a detection method that identifies dynamically active clusters in the redMaPPer Sloan Digital Sky Survey DR8 photometric galaxy cluster catalog. The Champagne Cluster exhibits the classic X-ray morphology of a post-pericenter dissociative galaxy cluster merger: an X-ray peak located between two galaxy overdensities at the same redshift. We conducted a Keck/DEIMOS survey and obtained redshifts for 102 member galaxies. The redshift analysis indicates a relative velocity of 411 ± 180 km s −1 between the two subclusters, which suggests that the merger is happening near the plane of the sky. We estimated the bulk temperature (8.20 ± 1.2 keV) and total X-ray luminosity (7.29 ± 0.19 × 10 44 erg s −1 ) of the intracluster medium using Chandra archival data. We used the ClusterPyXT software to make a temperature map, and we compared it to hydrodynamic simulations to constrain the time since pericenter (TSP), the impact parameter, and the mass ratio. We found two scenarios that matched our data: a returning system with an impact parameter of 0 and TSP of 2.2 Gyr, and an outbound system with an impact parameter of 500 kpc and TSP of 0.4 Gyr. Both scenarios have a mass ratio of 1:10.}, archive = {J_ApJ}, author = {Faik Bouhrik and Rodrigo Stancioli and David Wittman}, doi = {10.3847/1538-4357/ade67c}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {166}, shortjournal = {The Astrophys. J.}, title = {Discovery and multiwavelength analysis of a new dissociative galaxy cluster merger: The champagne cluster}, volume = {988}, year = {2025}, }
• (2025). Kinematic confirmation of a remarkable linear trail of galaxies in the NGC 1052 field, consistent with formation in a high-speed bullet dwarf collision. ApJ, 988(2), 165. (www)

  @article{ , abstract = {A unique linear trail of diffuse galaxies was recently identified in the NGC 1052 field. This trail includes the remarkable, ultradiffuse galaxies DF2 and DF4, which lack dark matter and host unusually luminous globular clusters. It has been proposed that the trail formed via a high-speed collision between two gas-rich dwarf galaxies. This scenario predicts that the trail galaxies are kinematically connected and follow a specific trend in radial velocity as a function of position, based on the known velocities and positions of DF2 and DF4. To test this hypothesis, we measured radial velocities for seven additional galaxies on the trail. While the galaxies’ low surface brightnesses presented observational challenges, we employ several methods to obtain measurements for galaxies with effective surface brightnesses up to 28.6 mag arcsec −2 , including a narrow slit placed over globular clusters and a novel wide slit mode on Keck/Low Resolution Imaging Spectrometer (LRIS), as well as a “light bucket” mode on Keck/Keck Cosmic Web Imager (KCWI). We find that five of our seven targets follow the precise velocity trend predicted by DF2 and DF4, to a degree with just a 2% chance of randomly occurring. Moreover, the trail galaxies’ radial velocities are significantly higher than those of the NGC 1052 group, setting it apart as a separate, kinematically connected system. Our findings support the theory that this trail of galaxies, including DF2 and DF4, formed together in a single event. A “bullet dwarf” collision remains the only known explanation for all the unusual properties of DF2, DF4, and the associated trail of galaxies.}, archive = {J_ApJ}, author = {Michael A. Keim and Pieter van Dokkum and Zili Shen and Harrison Souchereau and Imad Pasha and Shany Danieli and Roberto Abraham and Aaron J. Romanowsky and Yimeng Tang}, doi = {10.3847/1538-4357/addfd4}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {165}, shortjournal = {The Astrophys. J.}, title = {Kinematic confirmation of a remarkable linear trail of galaxies in the NGC 1052 field, consistent with formation in a high-speed bullet dwarf collision}, volume = {988}, year = {2025}, }
• (2025). Propagation-induced frequency-dependent polarization properties of fast radio burst. ApJ, 988(2), 164. (www)

  @article{ , abstract = {Frequency-dependent polarization properties provide crucial insights into the radiation mechanisms and magnetic environments of fast radio bursts (FRBs). We explore an analytical solution of radiative transfer of the polarization properties of FRBs as a strong incoming wave propagates in a homogeneous magnetized plasma. The cases of a thermal plasma are studied in detail. The rotational axis of the polarization spectrum undergoes precession with frequency on the Poincaré sphere when the medium has both strong Faraday rotation and conversion. Such precession on the Poincaré sphere could occur in hot or cold plasma with a strong magnetic field component perpendicular to the line of sight. Significant absorption can exist in a dense plasma medium, which may give rise to a highly circularly polarized outgoing wave. We apply the analytical solution with the mixing Faraday case to fit the observations of frequency-dependent Stokes parameters for FRB 20180301A and FRB 20201124A. The analytical solution offers a more physical description of FRBs’ magnetic environment properties than the empirical “generalized Faraday rotation” method commonly adopted in the literature. The frequency-dependent Stokes parameters may be associated with reversing rotation measures or the presence of a persistent radio source around an FRB.}, archive = {J_ApJ}, author = {Wei-Yang Wang and Xiaohui Liu and Dongzi Li and Bing Zhang and Chen-Hui Niu and Jifeng Liu and Renxin Xu and Weiwei Zhu and Kejia Lee}, doi = {10.3847/1538-4357/ade1d2}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {164}, shortjournal = {The Astrophys. J.}, title = {Propagation-induced frequency-dependent polarization properties of fast radio burst}, volume = {988}, year = {2025}, }
• (2025). Radio observation of the pulsar wind nebula in supernova remnant g11.2−0.3. ApJ, 988(2), 163. (www)

  @article{ , abstract = {Pulsar wind nebulae (PWNe) are important sources for understanding galactic high-energy processes, but it is controversial until now how high-energy particles in PWNe are accelerated and transported. Lacking radio counterparts of X-ray PWNe (the proposed acceleration sites) introduces difficulties to better understand questions about multiwavelengths. Our recent 3, 6, and 16 cm high-resolution observations of G11.2−0.3 PWN with the Australia Telescope Compact Array uniquely show morphological similarity with its X-ray PWN (a torus/jet feature). Spectral indices of the radio torus and jet are around −0.09 and −0.10, respectively. Meanwhile, for the jet region, the spectral break between radio and X-ray spectra implies particle acceleration mechanisms other than a diffusive shock acceleration. Polarization results suggest a helical B-field inside the jet, the equipartition B-field strength of which is below 100 μ G.}, archive = {J_ApJ}, author = {Yu Zhang and Yihan Liu and C.-Y. Ng and Mallory S. E. Roberts and Lili Yang}, doi = {10.3847/1538-4357/ade3d2}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {163}, shortjournal = {The Astrophys. J.}, title = {Radio observation of the pulsar wind nebula in supernova remnant g11.2−0.3}, volume = {988}, year = {2025}, }
• (2025). Constraining resolved extragalactic r21 variation with well-calibrated ALMA observations. ApJ, 988(2), 162. (www)

  @article{ , abstract = {CO(1–0) and CO(2–1) are commonly used as bulk molecular gas tracers. The CO line ratios (especially CO(2–1)/CO(1–0)– R 21 ) vary within and among galaxies, yet previous studies on R 21 and alike often rely on measurements constructed by combining data from facilities with substantial relative calibration uncertainties that have the same order as physical line ratio variations. Hence, robustly determining systematic R 21 variations is challenging. Here, we compare CO(1–0) and CO(2–1) mapping data from ALMA for 14 nearby galaxies, at a common physical resolution of 1.7 kpc. Our data set includes new ALMA (7 m+TP) CO(1–0) maps of 12 galaxies. We investigate R 21 variation to understand its dependence on global galaxy properties, kiloparsec-scale environmental factors, and its correlation with star formation rate (SFR) surface density and metallicity. We find that the galaxy-to-galaxy scatter is 0.05 dex. This is lower than previous studies, which reported over 0.1 dex variation, likely reflecting significant flux calibration uncertainties in single-dish surveys. Within individual galaxies, R 21 has a typical mean value of ∼0.64 and 0.1 dex variation, with an increase to ∼0.75 toward galactic centers. We find strong correlations between R 21 and various galactic parameters, particularly SFR surface density, which shows a power-law slope of 0.10–0.11 depending on the adopted binning/fitting methods. Our findings suggest that, for studies covering main-sequence galaxy samples, assuming a fixed R 21 = 0.64 does not significantly bias kiloparsec-scale molecular gas mass estimates from CO(2–1). Instead, systematic uncertainties from flux calibration and the CO-to-H 2 conversion factor account for more systematic scatter of CO-derived molecular gas properties.}, archive = {J_ApJ}, author = {Jakob den Brok and Elias K. Oakes and Adam K. Leroy and Eric W. Koch and Antonio Usero and Erik W. Rosolowsky and Frank Bigiel and Jiayi Sun and Hao He and Ashley T. Barnes and Yixian Cao and Fu-Heng Liang and Hsi-An Pan and Toshiki Saito and Sumit K. Sarbadhicary and Thomas G. Williams}, doi = {10.3847/1538-4357/addf4c}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {162}, shortjournal = {The Astrophys. J.}, title = {Constraining resolved extragalactic r21 variation with well-calibrated ALMA observations}, volume = {988}, year = {2025}, }
• (2025). Globular clusters GMRT pulsar search (GCGPS). i. survey description, discovery and timing of the first pulsar in NGC6093 (M80). ApJ, 988(2), 161. (www)

  @article{ , abstract = {This paper describes the new Globular Clusters GMRT Pulsar Search survey. This survey aims to find millisecond pulsars (MSPs) in the globular clusters (GCs) of the Milky Way using the upgraded Giant Metrewave Radio Telescope (uGMRT). Using the uGMRT’s Band-4 (550–750 MHz) and Band-3 (300–500 MHz) receivers, this survey will eventually cover the GCs accessible to the uGMRT sky, avoiding GCs visible to the Five-hundred-meter Aperture Spherical Radio Telescope (i.e., −53° < δ < ​​​​​​−17°), and targeting GCs that have not been targeted with the sensitivity of this survey. In this paper, we present the discovery and follow-up study of the first pulsar from this survey, J1617–2258A, a 4.32 ms binary MSP, the first to be discovered in the GC NGC 6093. We localized this MSP with arcsecond precision from imaging and obtained the unique timing solution from more than one year of timing observations with the uGMRT Band-4 (550–750 MHz) receivers. This revealed an unusual binary MSP, with a ∼19 hr, highly eccentric ( e ∼ 0.54) orbit having a low-mass companion. This orbital eccentricity allowed the measurement of the rate of advance of the periastron for this system, which led to the derivation of its total mass, 1.67 ± 0.06 M ⊙ ; this together with the system’s mass function implies, for the pulsar and the companion, M p < 1.60 M ⊙ and M c > 0.072 M ⊙ . The system is most likely a perturbed MSP–helium white dwarf system seen at a low orbital inclination.}, archive = {J_ApJ}, author = {Jyotirmoy Das and Jayanta Roy and Paulo C. C. Freire and Scott M. Ransom and Bhaswati Bhattacharyya and Karel Adámek and Wes Armour and Sanjay Kudale and Mekhala V. Muley}, doi = {10.3847/1538-4357/ade052}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {161}, shortjournal = {The Astrophys. J.}, title = {Globular clusters GMRT pulsar search (GCGPS). i. survey description, discovery and timing of the first pulsar in NGC6093 (M80)}, volume = {988}, year = {2025}, }
• (2025). Self-similar decomposition of the hierarchical merger tree of dark matter halos. ApJ, 988(2), 160. (www)

  @article{ , abstract = {In the ΛCDM universe, structure formation is generally not a self-similar process, while some self-similarity remains in certain statistics, which can greatly simplify our description and understanding of the cosmic structures. In this work, we show that the merger tree of dark matter halos is approximately self-similar by investigating the universality of the subhalo peak mass function (PMF) describing the mass distribution of progenitor halos. Using a set of cosmological simulations and identifying subhalos of different merger levels with hbt+ , we verify that the level-1 subhalo PMF is close to universal across halo mass, redshift, and cosmology. This approximate self-similarity allows us to analytically derive the subhalo PMF for subhalos accreted at any level (i.e., for sub-subhalos) through self-convolutions of the level-1 PMF, and the resulting model shows good agreement with simulation measurements. We further derive a number of analytical properties of the hierarchical origin of subhalos. We show that higher-level subhalos dominate at progressively lower peak mass in the PMF and are more likely to originate from major mergers than lower-level ones. At a given merger mass ratio, the subhalo accretion rates at each level track the growth rate of the host halo. At a fixed final mass ratio, however, subhalos of higher-level, higher-mass-ratio, and in more massive haloes tend to be accreted more recently. Matching subhalo peak mass to galaxy mass, these results have direct implications on the hierarchical origin of satellite galaxies.}, archive = {J_ApJ}, author = {Wenkang Jiang and Jiaxin Han and Fuyu Dong and Feihong He}, doi = {10.3847/1538-4357/ade439}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {160}, shortjournal = {The Astrophys. J.}, title = {Self-similar decomposition of the hierarchical merger tree of dark matter halos}, volume = {988}, year = {2025}, }
• (2025). Residual test to search for microlensing signatures in strongly lensed gravitational wave signals. ApJ, 988(2), 159. (www)

  @article{ , abstract = {When a gravitational wave signal encounters a massive object, such as a galaxy or galaxy cluster, it undergoes strong gravitational lensing, producing multiple copies of the original signal. These strongly lensed signals exhibit identical waveform morphology in the frequency domain, allowing analysis without the need for complex lens models. However, stellar fields and dark matter substructures within the galactic lens introduce microlensing effects that alter individual signal morphologies. Identifying these microlensing signatures is computationally challenging within Bayesian frameworks. In this study, we propose a residual test to efficiently search for microlensing signatures by leveraging the fact that current Bayesian inference pipelines are optimized solely for the strong lensing hypothesis. Using cross-correlation techniques, we investigate the microlensing-induced deviations from the strong hypothesis, which are imprinted in the residuals. Most simulated signals from our realistic microlensing populations exhibit small mismatches (MMs) between the microlensed and unlensed waveforms, but a fraction show significant deviations. We find that 28% (52%) and 34% (66%) of microlensed events with MM ≥0.03 and ≥0.1, respectively, can be discerned with O4 (O5) detector sensitivities, which demonstrates that high-MM events are more likely to be identified as microlensed. Including all events from a realistic population, 11% (21.5%) are identifiable with O4 (O5) sensitivity using our approach.}, archive = {J_ApJ}, author = {Eungwang Seo and Xikai Shan and Justin Janquart and Otto Hannuksela and Martin Hendry and Bin Hu}, doi = {10.3847/1538-4357/ade4bf}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {159}, shortjournal = {The Astrophys. J.}, title = {Residual test to search for microlensing signatures in strongly lensed gravitational wave signals}, volume = {988}, year = {2025}, }
• (2025). The optimal padé polynomial for reconstruction of luminosity distance based on 10-fold cross validation. ApJ, 988(2), 158. (www)

  @article{ , abstract = {The cosmography known as the Padé polynomials has been widely used in the reconstruction of luminosity distance, and the orders of Padé polynomials influence the reconstructed result derived from Padé approximation. In this paper, we present a more general scheme of selecting optimal Padé polynomial for reconstruction of luminosity distance based on 10-fold cross validation. Then the proposed scheme is applied to Pantheon+ data set. The numerical results clearly indicate that the proposed procedure has a remarkable ability to distinguish Padé approximations with different orders for the reconstruction of the luminosity distance. We conclude that the (2,1) Padé approximation is the optimal approach that can well explain Pantheon+ data at low and high redshifts. Future applications of this scheme could help choose the optimal model that is more suitable for cosmological observation data at hand and gain a deeper understanding of the Universe.}, archive = {J_ApJ}, author = {Bo Yu and Wen-Hu Liu and Xiaofeng Yang and Tong-Jie Zhang and Yanke Tang}, doi = {10.3847/1538-4357/adeb81}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {158}, shortjournal = {The Astrophys. J.}, title = {The optimal padé polynomial for reconstruction of luminosity distance based on 10-fold cross validation}, volume = {988}, year = {2025}, }
• (2025). XMM-newton conclusively identifies an active galactic nucleus in a green pea galaxy*. ApJ, 988(2), 157. (www)

  @article{ , abstract = {Green Pea galaxies are a class of compact, low-mass, low-metallicity star-forming galaxies in the relatively local Universe. They are believed to be analogs of high-redshift galaxies that reionized the Universe, and, indeed, the James Webb Space Telescope (JWST) is now uncovering such populations at record redshifts. Intriguingly, JWST finds evidence suggestive of active galactic nuclei (AGN) in many of these distant galaxies, including the elusive Little Red Dots, which broadly lack any detectable X-ray counterparts. Intuitively, one would expect to detect an AGN in their low-redshift analogs with X-rays, yet no study to date has conclusively identified an X-ray AGN within a Green Pea galaxy. Here we present the deepest X-ray campaign of a Green Pea galaxy performed to date, obtained with the goal of discerning the presence of a (potentially low-luminosity) AGN. The target—SDSS J082247.66+224144.0 (hereafter J0822+2241)—was previously found to display a comparable X-ray spectral shape to more local AGN (Γ ∼ 2) and a high luminosity ( L 2−10 keV ∼ 10 42 erg s −1 ). We show that over 6.2 yr (rest frame) the 2–10 keV luminosity of J0822+2241 is constant, whereas the soft 0.5–2 keV flux has decreased significantly by ∼60%. We discuss possible scenarios to explain the X-ray properties of J0822+2241, finding transient low column density obscuration surrounding an AGN to be the only plausible scenario. J0822+2241 thus provides further evidence that low-luminosity AGN activity could have contributed to the epoch of reionization and that local analogs are useful to derive a complete multiwavelength picture of black hole growth in high-redshift, low-luminosity AGNs.}, archive = {J_ApJ}, author = {Peter G. Boorman and Jiří Svoboda and Daniel Stern and Bret D. Lehmer and Abhijeet Borkar and Murray Brightman and Hannah P. Earnshaw and Fiona A. Harrison and Konstantinos Kouroumpatzakis and Barbora Adamcová and Roberto J. Assef and Matthias Ehle and Brian Grefenstette and Romana Grossová and Maitrayee Gupta and Elias Kammoun and Taiki Kawamuro and Lea Marcotulli and Romana Mikušincová and Matthew J. Middleton and Edward Nathan and Joanna M. Piotrowska and Jean J. Somalwar and Núria Torres-Albà and Dominic J. Walton and Daniel R. Weisz}, doi = {10.3847/1538-4357/add727}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {157}, shortjournal = {The Astrophys. J.}, title = {XMM-newton conclusively identifies an active galactic nucleus in a green pea galaxy*}, volume = {988}, year = {2025}, }
• (2025). All-sky kinematics of the distant halo: The reflex response to the LMC. ApJ, 988(2), 156. (www)

  @article{ , abstract = {The infall of the Large Magellanic Cloud (LMC) is predicted to displace the inner Milky Way (MW), imprinting an apparent “reflex motion” on the observed velocities of distant halo stars. We construct the largest all-sky spectroscopic data set of luminous red giant stars from 50–160 kpc, including a new survey of the southern celestial hemisphere. We fit the full 6D kinematics of our data to measure the amplitude and direction of the inner MW’s motion toward the outer halo. The observed velocity grows with distance such that, relative to halo stars at 100 kpc, the inner MW is lurching at ≈40 km s −1 toward a recent location along the LMC’s past orbit. Our measurements align with N -body simulations of the halo’s response to a 1.8 × 10 11 M ⊙ LMC on first infall, suggesting that the LMC is at least 15% as massive as the MW. Our findings highlight the dramatic disequilibrium of the MW outskirts, and will enable more accurate measurements of the total mass of our Galaxy.}, archive = {J_ApJ}, author = {Vedant Chandra and Rohan P. Naidu and Charlie Conroy and Nicolas Garavito-Camargo and Chervin Laporte and Ana Bonaca and Phillip A. Cargile and Emily Cunningham and Jiwon Jesse Han and Benjamin D. Johnson and Hans-Walter Rix and Yuan-Sen Ting and Rebecca Woody and Dennis Zaritsky}, doi = {10.3847/1538-4357/addab6}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {156}, shortjournal = {The Astrophys. J.}, title = {All-sky kinematics of the distant halo: The reflex response to the LMC}, volume = {988}, year = {2025}, }
• (2025). The XMAGNET exascale MHD simulations of SMBH feedback in galaxy groups and clusters: Overview and preliminary cluster results. ApJ, 988(2), 155. (www)

  @article{ , abstract = {We present initial results from extremely well-resolved 3D magnetohydrodynamical simulations of idealized galaxy clusters, conducted using the AthenaPK code on the Frontier exascale supercomputer. These simulations explore the self-regulation of galaxy groups and cool-core clusters by cold gas-triggered active galactic nucleus (AGN) feedback incorporating magnetized kinetic jets. Our simulation campaign includes simulations of galaxy groups and clusters with a range of masses and intragroup and intracluster medium properties. In this paper, we present results that focus on a Perseus-like cluster. We find that the simulated clusters are self-regulating, with the cluster cores staying at a roughly constant thermodynamic state and AGN jet power staying at physically reasonable values (≃10 44 –10 45 erg s –1 ) for billions of years without a discernible duty cycle. These simulations also produce significant amounts of cold gas, with calculations having strong magnetic fields generally both promoting cold gas formation and allowing cold gas out to much larger cluster-centric radii (≃100 kpc) than simulations with weak or no fields (≃10 kpc), and also having more filamentary cold gas morphology. We find that AGN feedback significantly increases the strength of magnetic fields at the center of the cluster. We also find that the magnetized turbulence generated by the AGN results in turbulence where the velocity power spectra are tied to AGN activity, whereas the magnetic energy spectra are much less impacted after reaching a stationary state.}, archive = {J_ApJ}, author = {Philipp Grete and Brian W. O’Shea and Forrest W. Glines and Deovrat Prasad and Benjamin D. Wibking and Martin Fournier and Marcus Brüggen and G. Mark Voit}, doi = {10.3847/1538-4357/adde45}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {155}, shortjournal = {The Astrophys. J.}, title = {The XMAGNET exascale MHD simulations of SMBH feedback in galaxy groups and clusters: Overview and preliminary cluster results}, volume = {988}, year = {2025}, }
• (2025). Ensemble modeling of the solar wind flow with boundary conditions governed by synchronic photospheric magnetograms. i. multipoint validation in the inner heliosphere. ApJ, 988(2), 154. (www)

  @article{ , abstract = {The solar wind (SW) is a vital component of space weather, providing a background for solar transients such as coronal mass ejections, stream interaction regions, and energetic particles propagating toward Earth. Accurate prediction of space weather events requires a precise description and thorough understanding of physical processes occurring in the ambient SW plasma. Ensemble simulations of the 3D SW flow are performed using an empirically driven magnetohydrodynamic heliosphere model implemented in the Multi-Scale Fluid-Kinetic Simulation Suite (MS-FLUKSS). The effect of uncertainties in the photospheric boundary conditions on the simulation outcome is investigated. The MS-FLUKSS simulation results are in good overall agreement with the observations from the Parker Solar Probe, Solar Orbiter, Solar Terrestrial Relations Observatory, and OMNI data at Earth, specifically during 2020–2021. This makes it possible to shed more light on the properties of the SW propagating through the heliosphere and perspectives for improving space weather forecasts.}, archive = {J_ApJ}, author = {Dinesha V. Hegde and Tae K. Kim and Nikolai V. Pogorelov and Shaela I. Jones and Charles N. Arge}, doi = {10.3847/1538-4357/addf33}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {154}, shortjournal = {The Astrophys. J.}, title = {Ensemble modeling of the solar wind flow with boundary conditions governed by synchronic photospheric magnetograms. i. multipoint validation in the inner heliosphere}, volume = {988}, year = {2025}, }
• (2025). A multi-wavelength characterization of the 2023 outburst of MAXI j1807+132: Manifestations of disk instability and jet emission. ApJ, 988(2), 153. (www)

  @article{ , abstract = {Several phenomenological aspects of low-luminosity neutron star transients, such as atolls, remain poorly understood. One such source, MAXI J1807+132, entered its latest outburst in 2023 July. To thoroughly characterize this outburst, we conducted an extensive observational campaign spanning radio to X-ray wavelengths. Here we present the results of this campaign, which covered the period from before the outburst to the return to quiescence. We detected a delay between the X-ray and optical rise times, which is consistent with the predictions of the disk instability model with a truncated disk. The color evolution and optical/X-ray correlations, along with infrared and radio detections, support the presence of jet synchrotron emission during the gradual decay phase following the peak. We also report for the first time in an X-ray binary a near-orthogonal rotation of the optical polarization just before a small flare, after which the jet is thought to be quenched. The main outburst is followed by several high-amplitude, rapid reflares in the optical, ultraviolet, and X-ray bands, the origin of which remains difficult to constrain.}, archive = {J_ApJ}, author = {Sandeep K. Rout and M. Cristina Baglio and Andrew K. Hughes and David M. Russell and D. M. Bramich and Payaswini Saikia and Kevin Alabarta and Montserrat Armas Padilla and Sergio Campana and Stefano Covino and Paolo D’Avanzo and Rob Fender and Paolo Goldoni and Jeroen Homan and Fraser Lewis and Nicola Masetti and Sara Motta and Teo Muñoz-Darias and Alessandro Papitto and Thomas D. Russell and Gregory Sivakoff and Jakob van den Eijnden}, doi = {10.3847/1538-4357/ade14c}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {153}, shortjournal = {The Astrophys. J.}, title = {A multi-wavelength characterization of the 2023 outburst of MAXI j1807+132: Manifestations of disk instability and jet emission}, volume = {988}, year = {2025}, }
• (2025). Connecting the small solar wind transients observed remotely to their in situ measurement near 1 au. ApJ, 988(2), 152. (www)

  @article{ , abstract = {Based on the two-vantage observations by the COR2 coronagraphs on board the two STEREO spacecraft between 2010 January 1 and 2010 July 15, we reconstruct the three-dimensional (3D) structures of small solar wind transients in the extended corona and determine their velocities by using the CORrelation-Aided Reconstruction technique. From this data set, we select three small transient events that are predicted to arrive at the L1 point after extrapolating their 3D trajectories in the heliosphere. We find that the predicted trajectories are consistent with the heliospheric observations, and the transients are likely to have also been detected by in situ instruments at L1. The case 1 event is a streamer blob associated with high-density regions across the heliospheric current sheet detected 2 days before the occurrence of a stream interaction region (SIR). The case 2 transient is identified as the bright core of a streamer blowout coronal mass ejection entrained by an SIR, and the case 3 event is merged with the SIR-compressed outflow. The in situ properties related to these events and their ambient plasma flows are consistent with the properties of their source regions, identified after tracing their motion back to the solar surface. This work is an attempt to establish an exact connection between the coronal observations of a small solar wind transient and its in situ measurement at near 1 au and to understand the evolution of solar wind transients in the heliosphere.}, archive = {J_ApJ}, author = {Shaoyu Lyu and Yuming Wang and Christopher J. Owen}, doi = {10.3847/1538-4357/ade1d7}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {152}, shortjournal = {The Astrophys. J.}, title = {Connecting the small solar wind transients observed remotely to their in situ measurement near 1 au}, volume = {988}, year = {2025}, }
• (2025). Modeling of ionization and recombination processes in plasma with arbitrary non-maxwellian electron distribution. ApJ, 988(2), 151. (www)

  @article{ , abstract = {In astronomical environments, the high-temperature emission of plasma mainly depends on ion charge states, requiring accurate analysis of the ionization and recombination processes. For various phenomena involving energetic particles, non-Maxwellian distributions of electrons exhibiting high-energy tails can significantly enhance the ionization process. Therefore, accurately computing ionization and recombination rates with non-Maxwellian electron distributions is essential for emission diagnostic analysis. In this work, we report two methods for fitting various non-Maxwellian distributions by using the Maxwellian decomposition strategy. For standard κ -distributions, the calculated ionization and recombination rate coefficients show comparable accuracy to other public packages. Additionally, our methods support arbitrary electron distributions and can be easily extended to updated atomic databases. We apply the above methods to two specific non-Maxwellian distribution scenarios: (i) accelerated electron distributions due to magnetic reconnection revealed in a combined MHD–particle simulation; and (ii) the high-energy truncated κ -distribution predicted by the exospheric model of the solar wind. During the electron acceleration process, we show that the ionization rates of high-temperature iron ions increase significantly compared to their initial Maxwellian distribution, while the recombination rates may decrease due to the electron distribution changes in low-energy ranges. This can potentially lead to an overestimation of the plasma temperature when analyzing the Fe emission lines under the Maxwellian distribution assumption. For the truncated κ -distribution in the solar wind, our results show that the ionization rates are lower than those for the standard κ -distribution, while the recombination rates remain similar. This leads to an overestimation of the plasma temperature when assuming a κ -distribution.}, archive = {J_ApJ}, author = {Chengcai Shen and Xiaocan Li and Yuan-Kuen Ko and John C. Raymond and Fan Guo and Vanessa Polito and Viviane Pierrard}, doi = {10.3847/1538-4357/ade2cf}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {151}, shortjournal = {The Astrophys. J.}, title = {Modeling of ionization and recombination processes in plasma with arbitrary non-maxwellian electron distribution}, volume = {988}, year = {2025}, }
• (2025). Concealing circumbinary planets with tidal shrinkage. ApJ, 988(2), 150. (www)

  @article{ , abstract = {Of the 14 transiting planets that have been detected orbiting eclipsing binaries (“circumbinary planets”), none have been detected with stellar binary orbital periods shorter than 7 days, despite such binaries existing in abundance. The eccentricity–period data for stellar binaries indicate that short-period (<7 days) binaries have had their orbits tidally circularized. We examine here to what extent tidal circularization and shrinkage can conceal circumbinary planets, i.e. whether planets actually exist around short-period binaries, but are not detected because their transit probabilities drop as tides shrink the binary away from the planet. We carry out a population synthesis by initializing a population of eccentric stellar binaries hosting circumbinary planets, and then circularizing and tightening the host orbits using stellar tides. To match the circumbinary transit statistics, stellar binaries must form with eccentricities ≳ 0.2 and periods ≳ 6 days, with circumbinary planets emplaced on exterior stable orbits before tidal circularization; moreover, tidal dissipation must be efficient enough to circularize and shrink binaries out to ∼6–8 days. The resultant binaries that shrink to sub-7 day periods no longer host transiting planets. However, this scenario cannot explain the formation of nearly circular, tight binaries, brought to their present sub-7 day orbits from other processes like disk migration. Still, tidal shrinkage can introduce a bias against finding transiting circumbinary planets, and predicts a population of KIC 3853259 (AB)b analogs consisting of wide-separation, nontransiting planets orbiting tight binaries.}, archive = {J_ApJ}, author = {Saahit Mogan and J.J. Zanazzi}, doi = {10.3847/1538-4357/ade2e8}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {150}, shortjournal = {The Astrophys. J.}, title = {Concealing circumbinary planets with tidal shrinkage}, volume = {988}, year = {2025}, }
• (2025). Galaxy cluster mass estimation through the splashback radius. ApJ, 988(2), 149. (www)

  @article{ , abstract = {We present an analysis of the splashback radius ( R sp ) and the associated splashback mass ( M sp ) for a sample of galaxy clusters using Sloan Digital Sky Survey spectroscopic data and mock simulations. R sp marks a physical boundary between the virialized core and the outer infall regions of clusters, providing a robust measure of cluster mass accretion history without being affected by pseudo-evolution. We model the cumulative galaxy number profile of clusters, testing different halo density models and considering the impact of cluster properties, such as center definitions, magnitude limits, galaxy colors, and field contamination, on the estimation of splashback features. Our results show that observed splashback radii, measured in projection (2D), are consistently smaller than predicted by dark matter simulations, with R sp / R 200m ≈ 1, supporting previous discrepancies in the literature. We also explore the relationship between M sp and R sp , proposing a new scaling relation for future cosmological studies, as R sp is easily observable. Our findings indicate that splashback masses strongly correlate with radii, with a dispersion of ≈0.15 dex, competitive with other mass-observable relations. However, the fitted relation diverges from the constant density expectations of galaxy clusters around R sp . Additionally, the M sp – R sp relation shows significant redshift evolution, though the predominantly low-redshift range of our sample limits our ability to confirm this trend conclusively. The approach developed here may play a key role in cluster characterization and cosmology in the era of large galaxy surveys.}, archive = {J_ApJ}, author = {Lucas Gabriel-Silva and Laerte Sodré}, doi = {10.3847/1538-4357/ade308}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {149}, shortjournal = {The Astrophys. J.}, title = {Galaxy cluster mass estimation through the splashback radius}, volume = {988}, year = {2025}, }
• (2025). Detected abundances of nuclei relative to 26Fe for elements 14Si through 44Ru with CALET on the international space station. ApJ, 988(2), 148. (www)

  @article{ , abstract = {The Calorimetric Electron Telescope (CALET), launched to the International Space Station (ISS) in 2015 August and continuously operating since, measures cosmic-ray (CR) electrons, nuclei, and gamma rays. CALET, with its 27 radiation length deep Total Absorption Calorimeter, measures particle energy and allows for the measurement of spectra, secondary to primary ratios of the more abundant CR nuclei through 28 Ni, while the main charge detector can measure ultra-heavy CR nuclei through 44 Ru. The results for the abundances of elements from Z = 14 to Z = 44 relative to 26 Fe over 7.5 yr of observation are presented here and compared to previous measurements from ACE-CRIS, SuperTIGER, and HEAO-3.}, archive = {J_ApJ}, author = {O. Adriani and Y. Akaike and K. Asano and Y. Asaoka and E. Berti and P. Betti and G. Bigongiari and W. R. Binns and M. Bongi and P. Brogi and A. Bruno and N. Cannady and G. Castellini and C. Checchia and M. L. Cherry and G. Collazuol and G. A. de Nolfo and K. Ebisawa and A. W. Ficklin and H. Fuke and S. Gonzi and T. G. Guzik and T. Hams and K. Hibino and M. Ichimura and M. H. Israel and K. Kasahara and J. Kataoka and R. Kataoka and Y. Katayose and C. Kato and N. Kawanaka and Y. Kawakubo and K. Kobayashi and K. Kohri and H. S. Krawczynski and J. F. Krizmanic and P. Maestro and P. S. Marrocchesi and M. Mattiazzi and A. M. Messineo and J. W. Mitchell and S. Miyake and A. A. Moiseev and M. Mori and N. Mori and H. M. Motz and K. Munakata and S. Nakahira and J. Nishimura and M. Negro and S. Okuno and J. F. Ormes and S. Ozawa and L. Pacini and P. Papini and B. F. Rauch and S. B. Ricciarini and K. Sakai and T. Sakamoto and M. Sasaki and Y. Shimizu and A. Shiomi and P. Spillantini and F. Stolzi and S. Sugita and A. Sulaj and M. Takita and T. Tamura and T. Terasawa and S. Torii and Y. Tsunesada and Y. Uchihori and E. Vannuccini and J. P. Wefel and K. Yamaoka and S. Yanagita and A. Yoshida and K. Yoshida and W. V. Zober and The CALET Collaboration}, doi = {10.3847/1538-4357/ade3cc}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {148}, shortjournal = {The Astrophys. J.}, title = {Detected abundances of nuclei relative to 26Fe for elements 14Si through 44Ru with CALET on the international space station}, volume = {988}, year = {2025}, }
• (2025). Electron-scale Kelvin–Helmholtz instabilities in magnetized shear flows. ApJ, 988(2), 147. (www)

  @article{ , abstract = {Electron-scale Kelvin–Helmholtz instabilities (ESKHIs) are found in several astrophysical scenarios. Naturally, ESKHIs are subject to a background magnetic field, but an analytical dispersion relation and an accurate growth rate of ESKHI under this circumstance have remained open because former magnetohydrodynamics derivations are not applicable in the relativistic regime. We present a generalized dispersion relation of ESKHI in relativistic magnetized shear flows, with two-fluid equations in the cold limit. ESKHI linear growth rates in certain cases are numerically calculated. The results show that when the shear velocity is relatively small, the presence of an external magnetic field results in a decreased maximum instability growth rate, a larger cutoff wavenumber of the unstable band, and an increased wavenumber of the most unstable mode. However, when the shear velocity is sufficiently high, the external magnetic field can increase the maximum instability growth rate instead. Particle-in-cell simulations are also carried out to verify our conclusions. In simulations, we observe the generation of a kinetic direct-current (DC) magnetic field, which is shown to have a strong impact on ESKHIs. In the presence of an external magnetic field, the DC magnetic field generation is suppressed because of electron gyration across the shear interface. Beyond the stabilizing threshold external magnetic field predicted by our fluid theory, we further observe possible evidence of Weibel instabilities.}, archive = {J_ApJ}, author = {Yao Guo and Dong Wu and Jie Zhang}, doi = {10.3847/1538-4357/ade3cf}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {147}, shortjournal = {The Astrophys. J.}, title = {Electron-scale Kelvin–Helmholtz instabilities in magnetized shear flows}, volume = {988}, year = {2025}, }
• (2025). New field OB and OBe binaries of the SMC wing: Observational properties and population modeling. ApJ, 988(2), 146. (www)

  @article{ , abstract = {We present a radial velocity (RV) survey of the field OB and OBe stars of the SMC Wing. We use multiepoch observations of 55 targets obtained with the Magellan Inamori-Magellan Aerial Camera and Spectrograph and M2FS multi-object spectrographs to identify single- and double-lined spectroscopic binaries. We also use TESS light curves to identify new eclipsing binary candidates. We find that 10 each of our 34 OB (29%) and 21 OBe (48%) stars are confirmed binaries, and at least ∼6 more are candidates. Using our RV measurements, we set constraints on the companion masses, and in some cases, on periods, eccentricities, and inclinations. The RV data suggest that OB binaries favor more circular orbits (mean eccentricity 〈 e 〉 = 0.08 ± 0.02), while OBe binaries are eccentric (〈 e 〉 = 0.45 ± 0.04). We identify two candidate black hole binaries, [M2002] 77616, and 81941. We use Binary Population and Spectral Synthesis to predict the frequencies of ejected OB and OBe stars and binaries, assuming OBe stars are binary mass gainers ejected by the companion supernova. We also predict the frequencies of black-hole, neutron-star, and stripped-star companions, and we model the distributions of primary and secondary masses, periods, eccentricities, and velocity distributions. The models are broadly consistent with the binary origin scenario for OBe stars, and predict an even larger number of post-supernova OB binaries. Comparison with the kinematics supports a significant contribution from dynamical ejections for both OB and OBe stars, although less so for binaries.}, archive = {J_ApJ}, author = {Irene Vargas-Salazar and M. S. Oey and Jan J. Eldridge and Drew Weisserman and Helen C. Januszewski and Juliette C. Becker and Stefano Zazzera and Norberto Castro and Yongjung Kim and Kaitlin M. Kratter and Mario Mateo and John I. Bailey}, doi = {10.3847/1538-4357/ade523}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {146}, shortjournal = {The Astrophys. J.}, title = {New field OB and OBe binaries of the SMC wing: Observational properties and population modeling}, volume = {988}, year = {2025}, }
• (2025). Erratum: “Evidence for YORP-induced spin deceleration in asteroid (433) eros” (2025, ApJ, 986, 172). ApJ, 988(1), 145. (www)

  @article{ , archive = {J_ApJ}, author = {Shuai Feng and Shaoming Hu and Xu Chen and Liyong Zhou and Yangbo Xu and Zehua Qi}, doi = {10.3847/1538-4357/ade8ec}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {145}, shortjournal = {The Astrophys. J.}, title = {Erratum: “Evidence for YORP-induced spin deceleration in asteroid (433) eros” (2025, ApJ, 986, 172)}, volume = {988}, year = {2025}, }
• (2025). Shock acceleration via idealized short large-amplitude magnetic structures. ApJ, 988(1), 144. (www)

  @article{ , abstract = {To accelerate cosmic rays (CRs) to ∼PeV energies, diffusive shock acceleration (DSA) in Galactic supernova remnants requires amplified magnetic turbulence in the shock to facilitate broadband Bohm diffusion of CRs. Recent particle-in-cell (PIC) shock simulations suggest that diffusion may be driven by short large-amplitude magnetic structures (SLAMS). Persistent SLAMS develop in the upstream of shocks with an Alfvénic Mach number M A ≳ 20 via the Bell instability and nonlinear amplification/steepening. We employ test-particle simulations to examine particle transport and acceleration in model shocks populated by analytically prescribed, idealized SLAMS that approximate the magnetic structures of PIC shock simulations. We demonstrate that SLAMS drive broadband Bohm diffusion of magnetized electrons (i.e., electron Larmor radius r L ≪  magnetic-structure length λ AM ) and unmagnetized electrons (i.e., r L ≫ λ AM ). We show that SLAMS accelerate unmagnetized electrons via DSA, and magnetized electrons via shock drift acceleration (SDA) and quasi-periodic shock acceleration (QSA). QSA, a novel Fermi-type mechanism, proceeds via rapid scattering in the converging flow between the first upstream magnetic structure and the near-downstream, shock-amplified field. QSA becomes vital for maintaining electron acceleration in shocks with superluminal SLAMS, which strongly advect magnetized electrons due to high inclination between field lines and the flow. We find that test-electron spectra are consistent with spectra from PIC simulations, indicating that the test-particle method can be used to extrapolate PIC results to longer spatial and temporal scales. Overall, our results suggest that SLAMS in M A ≳ 20 shocks may play an important role in facilitating shock acceleration.}, archive = {J_ApJ}, author = {Zachary Hemler and Anatoly Spitkovsky and Vladimir Zeković}, doi = {10.3847/1538-4357/adb7e3}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {144}, shortjournal = {The Astrophys. J.}, title = {Shock acceleration via idealized short large-amplitude magnetic structures}, volume = {988}, year = {2025}, }
• (2025). A poisson process AutoDecoder for X-ray sources. ApJ, 988(1), 143. (www)

  @article{ , abstract = {X-ray observing facilities, such as the Chandra X-ray Observatory and the eROSITA, have detected over a million astronomical sources associated with high-energy phenomena. The arrival of photons as a function of time follows a Poisson process and can vary by orders-of-magnitude, presenting obstacles for common tasks such as source classification, physical property derivation, and anomaly detection. Previous work has either failed to directly capture the Poisson nature of the data or only focuses on Poisson rate function reconstruction. In this work, we present the Poisson Process AutoDecoder (PPAD), which is a neural field decoder that maps fixed-length latent features to continuous Poisson rate functions across energy band and time via unsupervised learning. PPAD reconstructs the rate function and yields a representation at the same time. We demonstrate the efficacy of PPAD via reconstruction, regression, classification, and anomaly detection experiments using the Chandra Source Catalog.}, archive = {J_ApJ}, author = {Yanke Song and V. Ashley Villar and Rafael Martínez-Galarza and Steven Dillmann}, doi = {10.3847/1538-4357/add72e}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {143}, shortjournal = {The Astrophys. J.}, title = {A poisson process AutoDecoder for X-ray sources}, volume = {988}, year = {2025}, }
• (2025). Magnetic waves excited by newborn inner-source pickup h+ measured by the voyager spacecraft inside 3 au. ApJ, 988(1), 142. (www)

  @article{ , abstract = {In S. J. Hollick et al., we surveyed the Voyager magnetic field data from launch through 1990 where the Voyagers 1 and 2 spacecraft reach 43.5 au and 33.6 au, respectively. We identified 637 intervals of wave activity that could be attributed to either interstellar pickup He + , H + , or both. In our quest to identify and study low-frequency magnetic waves arising from interstellar pickup H + , we found 19 intervals, 16 with thermal ion data, within ∼3 au. We compared the growth rate of the waves with the rate of background turbulence they must overcome to reach observable levels. Ionization of interstellar neutral H is highly efficient, resulting in a factor of 10 reduction in density by 1 au relative to values at R > 10 au. At the same time, solar wind turbulence increases with decreasing distance to the Sun. This makes it unlikely that interstellar neutral hydrogen can penetrate within ∼3 au in sufficient number to explain the wave observations seen by the Voyager magnetometers. We consider the possibility that the so-called “inner source” for pickup H + arising from the interaction of solar wind protons with dust grains may account for the density of newborn pickup ions required for the growth of the observed waves. Although the Voyagers lack the instrumentation required to measure pickup ions, we do conclude that the inner-source theories provide a compelling explanation for the majority of the observations while it is possible that a few could be due to either interstellar ions or shocks.}, archive = {J_ApJ}, author = {Sophia J. Hollick and Charles W. Smith and Zackary B. Pine and Matthew R. Argall and Colin J. Joyce and Philip A. Isenberg and Philip R. Quinn and Bernard J. Vasquez and Nathan A. Schwadron and Justyna M. Sokół and Maciej Bzowski and Marzena A. Kubiak}, doi = {10.3847/1538-4357/addb4d}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {142}, shortjournal = {The Astrophys. J.}, title = {Magnetic waves excited by newborn inner-source pickup h+ measured by the voyager spacecraft inside 3 au}, volume = {988}, year = {2025}, }
• (2025). IceCube search for neutrino emission from X-ray bright seyfert galaxies. ApJ, 988(1), 141. (www)

  @article{ , abstract = {The recent IceCube detection of TeV neutrino emission from the nearby active galaxy NGC 1068 suggests that active galactic nuclei (AGNs) could make a sizable contribution to the diffuse flux of astrophysical neutrinos. The absence of TeV γ -rays from NGC 1068 indicates neutrino production in the vicinity of the supermassive black hole, where the high radiation density leads to γ -ray attenuation. Therefore, any potential neutrino emission from similar sources is not expected to correlate with high-energy γ -rays. Disk-corona models predict neutrino emission from Seyfert galaxies to correlate with keV X-rays because they are tracers of coronal activity. Using through-going track events from the Northern Sky recorded by IceCube between 2011 and 2021, we report results from a search for individual and aggregated neutrino signals from 27 additional Seyfert galaxies that are contained in the Swift's Burst Alert Telescope AGN Spectroscopic Survey. Besides the generic single power law, we evaluate the spectra predicted by the disk-corona model assuming stochastic acceleration parameters that match the measured flux from NGC 1068. Assuming all sources to be intrinsically similar to NGC 1068, our findings constrain the collective neutrino emission from X-ray bright Seyfert galaxies in the northern sky, but, at the same time, show excesses of neutrinos that could be associated with the objects NGC 4151 and CGCG 420-015. These excesses result in a 2.7 σ significance with respect to background expectations.}, archive = {J_ApJ}, author = {R. Abbasi and M. Ackermann and J. Adams and S. K. Agarwalla and J. A. Aguilar and M. Ahlers and J. M. Alameddine and N. M. Amin and K. Andeen and C. Argüelles and Y. Ashida and S. Athanasiadou and L. Ausborm and S. N. Axani and X. Bai and A. Balagopal V. and M. Baricevic and S. W. Barwick and S. Bash and V. Basu and R. Bay and J. J. Beatty and J. Becker Tjus and J. Beise and C. Bellenghi and C. Benning and S. BenZvi and D. Berley and E. Bernardini and D. Z. Besson and E. Blaufuss and L. Bloom and S. Blot and F. Bontempo and J. Y. Book Motzkin and C. Boscolo Meneguolo and S. Böser and O. Botner and J. Böttcher and J. Braun and B. Brinson and J. Brostean-Kaiser and L. Brusa and R. T. Burley and D. Butterfield and M. A. Campana and I. Caracas and K. Carloni and J. Carpio and S. Chattopadhyay and N. Chau and Z. Chen and D. Chirkin and S. Choi and B. A. Clark and A. Coleman and G. H. Collin and A. Connolly and J. M. Conrad and P. Coppin and R. Corley and P. Correa and D. F. Cowen and P. Dave and C. De Clercq and J. J. DeLaunay and D. Delgado and S. Deng and A. Desai and P. Desiati and K. D. de Vries and G. de Wasseige and T. DeYoung and A. Diaz and J. C. Díaz-Vélez and P. Dierichs and M. Dittmer and A. Domi and L. Draper and H. Dujmovic and K. Dutta and M. A. DuVernois and T. Ehrhardt and L. Eidenschink and A. Eimer and P. Eller and E. Ellinger and S. El Mentawi and D. Elsässer and R. Engel and H. Erpenbeck and J. Evans and P. A. Evenson and K. L. Fan and K. Fang and K. Farrag and A. R. Fazely and A. Fedynitch and N. Feigl and S. Fiedlschuster and C. Finley and L. Fischer and D. Fox and A. Franckowiak and S. Fukami and P. Fürst and J. Gallagher and E. Ganster and A. Garcia and M. Garcia and G. Garg and E. Genton and L. Gerhardt and A. Ghadimi and C. Girard-Carillo and C. Glaser and T. Glauch and T. Glüsenkamp and J. G. Gonzalez and S. Goswami and A. Granados and D. Grant and S. J. Gray and O. Gries and S. Griffin and S. Griswold and K. M. Groth and C. Günther and P. Gutjahr and C. Ha and C. Haack and A. Hallgren and L. Halve and F. Halzen and H. Hamdaoui and M. Ha Minh and M. Handt and K. Hanson and J. Hardin and A. A. Harnisch and P. Hatch and A. Haungs and J. Häussler and K. Helbing and J. Hellrung and J. Hermannsgabner and L. Heuermann and N. Heyer and S. Hickford and A. Hidvegi and C. Hill and G. C. Hill and K. D. Hoffman and S. Hori and K. Hoshina and M. Hostert and W. Hou and T. Huber and K. Hultqvist and M. Hünnefeld and R. Hussain and K. Hymon and A. Ishihara and W. Iwakiri and M. Jacquart and O. Janik and M. Jansson and G. S. Japaridze and M. Jeong and M. Jin and B. J. P. Jones and N. Kamp and D. Kang and W. Kang and X. Kang and A. Kappes and D. Kappesser and L. Kardum and T. Karg and M. Karl and A. Karle and A. Katil and U. Katz and M. Kauer and J. L. Kelley and M. Khanal and A. Khatee Zathul and A. Kheirandish and J. Kiryluk and S. R. Klein and A. Kochocki and R. Koirala and H. Kolanoski and T. Kontrimas and L. Köpke and C. Kopper and D. J. Koskinen and P. Koundal and M. Kovacevich and M. Kowalski and T. Kozynets and J. Krishnamoorthi and K. Kruiswijk and E. Krupczak and A. Kumar and E. Kun and N. Kurahashi and N. Lad and C. Lagunas Gualda and M. Lamoureux and M. J. Larson and S. Latseva and F. Lauber and J. P. Lazar and J. W. Lee and K. Leonard DeHolton and A. Leszczyńska and J. Liao and M. Lincetto and Q. R. Liu and Y. T. Liu and M. Liubarska and E. Lohfink and C. Love and C. J. Lozano Mariscal and L. Lu and F. Lucarelli and W. Luszczak and Y. Lyu and J. Madsen and E. Magnus and K. B. M. Mahn and Y. Makino and E. Manao and S. Mancina and W. Marie Sainte and I. C. Mariş and S. Marka and Z. Marka and M. Marsee and I. Martinez-Soler and R. Maruyama and F. Mayhew and F. McNally and J. V. Mead and K. Meagher and S. Mechbal and A. Medina and M. Meier and Y. Merckx and L. Merten and J. Micallef and J. Mitchell and T. Montaruli and R. W. Moore and Y. Morii and R. Morse and M. Moulai and T. Mukherjee and R. Naab and R. Nagai and M. Nakos and U. Naumann and J. Necker and A. Negi and L. Neste and M. Neumann and H. Niederhausen and M. U. Nisa and K. Noda and A. Noell and A. Novikov and A. Obertacke Pollmann and V. O’Dell and B. Oeyen and A. Olivas and R. Orsoe and J. Osborn and E. O’Sullivan and H. Pandya and N. Park and G. K. Parker and E. N. Paudel and L. Paul and C. Pérez de los Heros and T. Pernice and J. Peterson and S. Philippen and A. Pizzuto and M. Plum and A. Pontén and Y. Popovych and M. Prado Rodriguez and B. Pries and R. Procter-Murphy and G. T. Przybylski and C. Raab and J. Rack-Helleis and M. Ravn and K. Rawlins and Z. Rechav and A. Rehman and P. Reichherzer and E. Resconi and S. Reusch and W. Rhode and B. Riedel and A. Rifaie and E. J. Roberts and S. Robertson and S. Rodan and G. Roellinghoff and M. Rongen and A. Rosted and C. Rott and T. Ruhe and L. Ruohan and D. Ryckbosch and I. Safa and J. Saffer and D. Salazar-Gallegos and P. Sampathkumar and A. Sandrock and M. Santander and S. Sarkar and J. Savelberg and P. Savina and P. Schaile and M. Schaufel and H. Schieler and S. Schindler and B. Schlüter and F. Schlüter and N. Schmeisser and T. Schmidt and J. Schneider and F. G. Schröder and L. Schumacher and S. Sclafani and D. Seckel and M. Seikh and M. Seo and S. Seunarine and P. Sevle Myhr and R. Shah and S. Shefali and N. Shimizu and M. Silva and B. Skrzypek and B. Smithers and R. Snihur and J. Soedingrekso and A. Sègaard and D. Soldin and P. Soldin and G. Sommani and C. Spannfellner and G. M. Spiczak and C. Spiering and M. Stamatikos and T. Stanev and T. Stezelberger and T. Stürwald and T. Stuttard and G. W. Sullivan and I. Taboada and S. Ter-Antonyan and A. Terliuk and M. Thiesmeyer and W. G. Thompson and J. Thwaites and S. Tilav and K. Tollefson and C. Tönnis and S. Toscano and D. Tosi and A. Trettin and R. Turcotte and J. P. Twagirayezu and M. A. Unland Elorrieta and A. K. Upadhyay and K. Upshaw and A. Vaidyanathan and N. Valtonen-Mattila and J. Vandenbroucke and N. van Eijndhoven and D. Vannerom and J. van Santen and J. Vara and F. Varsi and J. Veitch-Michaelis and M. Venugopal and M. Vereecken and S. Verpoest and D. Veske and A. Vijai and C. Walck and A. Wang and C. Weaver and P. Weigel and A. Weindl and J. Weldert and A. Y. Wen and C. Wendt and J. Werthebach and M. Weyrauch and N. Whitehorn and C. H. Wiebusch and D. R. Williams and L. Witthaus and A. Wolf and M. Wolf and G. Wrede and X. W. Xu and J. P. Yanez and E. Yildizci and S. Yoshida and R. Young and S. Yu and T. Yuan and Z. Zhang and P. Zhelnin and P. Zilberman and M. Zimmerman}, doi = {10.3847/1538-4357/addd05}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {141}, shortjournal = {The Astrophys. J.}, title = {IceCube search for neutrino emission from X-ray bright seyfert galaxies}, volume = {988}, year = {2025}, }
• (2025). Tools for characterizing the numerical error of stellar oscillation codes. ApJ, 988(1), 140. (www)

  @article{ , abstract = {Stellar oscillation codes are software instruments that evaluate the normal-mode frequencies of an input stellar model. While inter-code comparisons are often used to confirm the correctness of calculations, they are not suitable for characterizing the numerical error of an individual code. To address this issue, we introduce a set of tools—“error measures”—that facilitate this characterization. We explore the behavior of these error measures as calculation parameters, such as the number of radial grid points used to discretize the oscillation equations, are varied, and we summarize this behavior via an idealized error model. While our analysis focuses on the GYRE code, it remains broadly applicable to other oscillation codes.}, archive = {J_ApJ}, author = {R. H. D. Townsend and R. V. Kuenzi and J. Christensen-Dalsgaard}, doi = {10.3847/1538-4357/addf32}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {140}, shortjournal = {The Astrophys. J.}, title = {Tools for characterizing the numerical error of stellar oscillation codes}, volume = {988}, year = {2025}, }
• (2025). SpecPT (Spectroscopy pre-trained transformer) model for extragalactic spectroscopy. i. architecture and automated redshift measurement. ApJ, 988(1), 139. (www)

  @article{ , abstract = {We introduce the Spectroscopy Pre-trained Transformer (SpecPT), a transformer-based model designed to analyze spectroscopic data, with applications in spectrum reconstruction and redshift measurement. Using the Early Data Release (EDR) of the Dark Energy Spectroscopic Instrument (DESI) survey, we evaluate SpecPT’s performance on two distinct data sets: the Bright Galaxy Survey (BGS) and Emission Line Galaxy (ELG) samples. SpecPT successfully reconstructs spectra, accurately capturing emission lines, absorption features, and continuum shapes while effectively reducing noise. For redshift prediction, SpecPT achieves competitive accuracy, with normalized median absolute deviation values of 0.0006 and 0.0008, and catastrophic outlier fractions of 0.20% and 0.80% for BGS and ELG, respectively. Notably, SpecPT performs consistently well across the full redshift range (0 < z < 1.6), demonstrating its versatility and robustness. By leveraging its learned latent representations, SpecPT lays the groundwork for a foundational spectroscopic model, with potential applications in outlier detection, interstellar medium property estimation, and transfer learning to other data sets. This work represents a first step in building a generalized framework for spectroscopic analysis, capable of scaling to the full DESI data set and beyond.}, archive = {J_ApJ}, author = {Rohan Pattnaik and Jeyhan S. Kartaltepe and Clive Binu}, doi = {10.3847/1538-4357/ade053}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {139}, shortjournal = {The Astrophys. J.}, title = {SpecPT (Spectroscopy pre-trained transformer) model for extragalactic spectroscopy. i. architecture and automated redshift measurement}, volume = {988}, year = {2025}, }
• (2025). No evidence of a dichotomy in the elliptical galaxy population. ApJ, 988(1), 138. (www)

  @article{ , abstract = {The advent of large integral field spectroscopic surveys has found that elliptical galaxies (EGs) can be divided into two classes: the fast rotators (whose kinematics are dominated by rotation) and the slow rotators (which exhibit slow or no rotation pattern). It is often suggested that while the slow rotators typically have boxy isophotal shapes, have a high α -to-iron abundance ratio, and are quite massive, the fast rotators often exhibit the opposite properties (that is, having disky isophotes, lower α -to-iron ratio, and of typical masses). Whether the EGs consist of two distinct populations (i.e., a dichotomy exists) remains an unsolved issue. To examine the existence of the dichotomy, we used a sample of 1895 EGs from the SDSS-IV MaNGA survey and measured robustly the stellar kinematics, isophotal shapes, and [Mg/Fe] ratio. We confirmed the previous finding that the bulk of the EGs are disky (65%) and fast rotators (67%), but we found no evidence supporting a dichotomy, based on a principal component analysis. The different classes (boxy/disky and slow/fast rotators) of EGs occupy slightly different loci in the principal component space. This may explain the observed trends that led to the premature support of a dichotomy based on small samples of galaxies.}, archive = {J_ApJ}, author = {Rogério Monteiro-Oliveira and Yen-Ting Lin and Wei-Huai Chen and Chen-Yu Chuang and Abdurro’uf and Po-Feng Wu}, doi = {10.3847/1538-4357/ade0ba}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {138}, shortjournal = {The Astrophys. J.}, title = {No evidence of a dichotomy in the elliptical galaxy population}, volume = {988}, year = {2025}, }
• (2025). A resonant beginning for the solar system’s terrestrial planets. ApJ, 988(1), 137. (www)

  @article{ , abstract = {In the past two decades, transit surveys have revealed a class of planets with thick atmospheres—sub-Neptunes—that must have completed their accretion in protoplanet disks. When planets form in the gaseous disk, the gravitational interaction with the disk gas drives their migration and results in the trapping of neighboring planets in mean motion resonances, though these resonances can later be broken when the damping effects of disk gas or planetesimals wane. It is widely accepted that the outer solar system gas-giant planets originally formed in a resonant chain, which was later disrupted by dynamical instabilities. Here, we explore whether the early formation of the terrestrial planets in a resonance chain (including Theia) can evolve to the present configuration. Using N -body simulations, we demonstrate that the giant planet instability would also have destabilized the terrestrial resonance chain, triggering Moon-forming giant impacts in 20%–50% of our simulated systems, dependent on the initial resonance architecture. After the instability, the eccentricity and inclination of the simulated planets match their present-day values. Under the proposed scenario, the current period ratio of 3.05 between Mars and Venus—devoid of any special significance in traditional late-formation models—naturally arises as a relic of the former resonance chain.}, archive = {J_ApJ}, author = {Shuo Huang and Chris W. Ormel and Simon Portegies Zwart and Eiichiro Kokubo and Tian Yi}, doi = {10.3847/1538-4357/ade25a}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {137}, shortjournal = {The Astrophys. J.}, title = {A resonant beginning for the solar system’s terrestrial planets}, volume = {988}, year = {2025}, }
• (2025). Born to be starless: Revisiting the missing satellite problem. ApJ, 988(1), 136. (www)

  @article{ , abstract = {The two massive galaxies in the Local Group both host substantially fewer satellites than the subhalos expected from the cold dark matter paradigm, and recent investigations have highlighted the interplay between baryons and dark matter. We investigate the processes that make subhalos starless, using high-resolution cosmological simulations. We find that the number of satellites around Milky Way analogs closely aligns with observations, which accords with recent studies. In our simulations, the majority of subhalos are devoid of stars, i.e., “starless.” We first examined supernova feedback and the environmental effects associated with subhalos’ orbital motion as candidates for their origin. However, neither seems to be the main driver. Supernova feedback causes a reduction in cold gas in “starred” subhalos, but its impact is not significant. In the case of starless subhalos, supernova feedback is irrelevant because most of them do not have in situ star formation in the first place. The orbital motion in dense environments causes the removal of gas in all subhalos, but it is not enough to remove preexisting stars. The key is found to be the effect of reionization instead. Starless subhalos are initially born in regions that are less efficient in accreting matter. This makes them lack sufficiently dense gas to self-shield from UV background heating, preventing their gas from cooling below the star formation threshold. This indicates that starless subhalos are not made but born.}, archive = {J_ApJ}, author = {Seyoung Jeon and Sukyoung K. Yi and Emanuele Contini and Yohan Dubois and San Han and Katarina Kraljic and Sebastien Peirani and Christophe Pichon and Jinsu Rhee}, doi = {10.3847/1538-4357/ade2e0}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {136}, shortjournal = {The Astrophys. J.}, title = {Born to be starless: Revisiting the missing satellite problem}, volume = {988}, year = {2025}, }
• (2025). The physical properties and morphologies of faint dusty star-forming galaxies identified with JWST. ApJ, 988(1), 135. (www)

  @article{ , abstract = {We identify a sample of 234 dusty star-forming galaxies (DSFGs) in the A2744 and GOODS-S fields using JWST/NIRCam-selected galaxies as priors for SCUBA-2 measurements. This method provides a large number of galaxies both above an 850 μ m flux of 2 mJy (47 bright DSFGs) and below (187 faint DSFGs), representing the largest sample of individually identified (i.e., not stacked) faint DSFGs to date. We observe that f F444W and f F150W are tightly correlated with redshift, with fainter sources lying at higher redshifts, suggesting that the observed near-IR flux may be an effective way of selecting high-redshift DSFGs. We study the physical properties and morphologies of the DSFGs through spectral energy distribution fitting and parametric surface brightness profile modeling. Other than the lower star formation rates (SFRs) and total infrared luminosities in the faint DSFGs (SFR =\,8{0}_{-45}^{+81} ; {L}_{{\rm{IR}}}=11.8{2}_{-0.36}^{+0.30} ) compared to the bright DSFGs (SFR =\,25{4}_{-131}^{+135} ; {L}_{{\rm{IR}}}=12.3{2}_{-0.30}^{+0.20} ), the populations have similar properties. The stellar masses do not appear to be strongly dependent on either the SFRs or the submillimeter flux. These results suggest that the faint DSFGs are drawn from the same population of galaxies as the bright DSFGs. Based on visual inspections, we find a lower merger fraction (∼21%) relative to previous Hubble Space Telescope–based studies, suggesting that dust attenuation may have impacted previous estimates of DSFG merger rates.}, archive = {J_ApJ}, author = {S. J. McKay and A. J. Barger and L. L. Cowie and M. J. Nicandro Rosenthal}, doi = {10.3847/1538-4357/ade394}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {135}, shortjournal = {The Astrophys. J.}, title = {The physical properties and morphologies of faint dusty star-forming galaxies identified with JWST}, volume = {988}, year = {2025}, }
• (2025). Physical constraint preserving higher-order finite volume schemes for divergence-free astrophysical MHD and RMHD. ApJ, 988(1), 134. (www)

  @article{ , abstract = {Higher-order finite volume schemes for magnetohydrodynamics (MHD) and relativistic magnetohydrodynamics (RMHD) are very valuable because they allow us to carry out astrophysical simulations with very high accuracy. However, astrophysical problems sometimes have unusually large Mach numbers, exceptionally high Lorentz factors, and very strong magnetic fields. All these effects cause higher-order codes to become brittle and prone to code crashes. In this paper, we document physical constraint preserving (PCP) methods for treating numerical MHD and RMHD. While unnecessary for standard problems, for stringent astrophysical problems, these methods show their value. We describe higher-order methods that allow divergence-free evolution of the magnetic field. We present a novel two-dimensional Riemann solver. This two-dimensional Riemann solver plays a key role in the design of PCP schemes for MHD and RMHD. We present a very simple PCP formulation and show how it is amalgamated with the evolution of face-centered magnetic fields. The methods presented here are time-explicit and do not add much to the computational cost. We show that the methods meet their design accuracies and work well on problems that would otherwise be considered too extreme for typical higher-order Godunov methods of the type used in computational astrophysics.}, archive = {J_ApJ}, author = {Dinshaw S. Balsara and Deepak Bhoriya and Chetan Singh and Harish Kumar and Roger Käppeli and Federico Gatti}, doi = {10.3847/1538-4357/ade397}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {134}, shortjournal = {The Astrophys. J.}, title = {Physical constraint preserving higher-order finite volume schemes for divergence-free astrophysical MHD and RMHD}, volume = {988}, year = {2025}, }
• (2025). Bright dots and coronal plume formation in sunspot penumbra. ApJ, 988(1), 133. (www)

  @article{ , abstract = {Coronal plumes are narrow, collimated structures that are primarily viewed above the solar poles and in coronal holes in the extreme ultraviolet, but also in sunspots. Open questions remain about plume formation, including the role of small-scale transients and whether plumes embedded in different magnetic field configurations have similar formation mechanisms. We report on coordinated Solar Orbiter/Extreme Ultraviolet Imager (EUI), Interface Region Imaging Spectrograph, and Solar Dynamics Observatory observations of the formation of a plume in sunspot penumbra in 2022 March. During this observation, Solar Orbiter was positioned near the Earth–Sun line and EUI observed at a 5 s cadence with a spatial scale of 185 km pixel −1 in the solar corona. We observe fine-scale dots at various locations in the sunspot, but the brightest and highest density of dots is at the plume base. Space-time maps along the plume axis show parabolic and V-shaped patterns, and we conclude that some of these dots are possible signatures of magneto-acoustic shocks. Compared to other radial cuts around the sunspot, along the plume shows the longest periods (∼7 minutes) and the most distinct tracks. Bright dots at the plume base are mostly circular and do not show elongations from a fixed origin, in contrast to jetlets and previously reported penumbral dots. We do not find high-speed, repeated downflows along the plume, and the plume appears to brighten coherently along its length. Our analysis suggests that jetlets and downflows are not a necessary component of this plume’s formation, and that mechanisms for plume formation could be dependent on magnetic topology and the chromospheric wave field.}, archive = {J_ApJ}, author = {Ayla Weitz and Sanjiv K. Tiwari and Gianna Cauzzi and Kevin P. Reardon and Bart De Pontieu}, doi = {10.3847/1538-4357/ade3c1}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {133}, shortjournal = {The Astrophys. J.}, title = {Bright dots and coronal plume formation in sunspot penumbra}, volume = {988}, year = {2025}, }
• (2025). Impeding turbulence decay in self-gravitating cloud cores. ApJ, 988(1), 132. (www)

  @article{ , abstract = {Turbulence governs the fragmentation of molecular clouds and plays a pivotal role in star formation. The persistence of observed cloud turbulence suggests it does not decay significantly within the turnover timescale, implying a recurrent driving mechanism. Although ubiquitous self-gravity is a plausible driver, magnetohydrodynamic simulations by E. C. Ostriker et al. in 2001 demonstrated that self-gravity alone does not modify the global turbulence decay rate. In this study, we demonstrate that the dominant diffuse volume of a cloud dictates its overall decay rate, while individual dense cores can maintain near-zero decay rates. Crucially, this phenomenon is absent in control simulations excluding self-gravity. This discrepancy cannot be attributed to contamination of turbulent velocities by core contraction because most cores in our simulations remain in a quasi-equilibrium state. Our analysis reveals that the gravitational potential energy released during core formation—not necessarily driven by self-gravity but also by turbulent compression—is sufficient to sustain the observed turbulence levels within cores.}, archive = {J_ApJ}, author = {Shibo Yuan and Hua-bai Li}, doi = {10.3847/1538-4357/ade5b6}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {132}, shortjournal = {The Astrophys. J.}, title = {Impeding turbulence decay in self-gravitating cloud cores}, volume = {988}, year = {2025}, }
• (2025). Radio continuum studies of ultracompact and short orbital period X-ray binaries. ApJ, 988(1), 131. (www)

  @article{ , abstract = {We present the radio continuum counterparts to the enigmatic ultracompact X-ray binaries (UCXBs): a black hole or neutron star accreting from a hydrogen-deficient white dwarf donor star with short orbital periods (<80 minutes). For the sample of UCXBs hosted by globular clusters (GCs), we search for whether certain GC properties are more likely to enhance UCXB formation. We determine that GCs that host UCXBs are drawn from a distinct population in terms of cluster concentration, core radius, and half-light radius, but are similar to other well-studied GCs in metallicity and cluster mass. In particular, UCXB-hosting GCs tend to be on average more compact, with a higher concentration than other GCs, with significantly higher encounter rates. We investigate whether a correlation exists between radio luminosity and orbital period, using new and archival observations. We determine that there is not a clear connection between the two observable quantities.}, archive = {J_ApJ}, author = {Kristen C. Dage and Teresa Panurach and Kwangmin Oh and Malu Sudha and Montserrat Armas Padilla and Arash Bahramian and Edward M. Cackett and Timothy J. Galvin and Craig O. Heinke and Renee Ludlam and Angiraben D. Mahida and Richard M. Plotkin and Thomas D. Russell and Susmita Sett and Payaswini Saikia and Aarran W. Shaw and Alexandra J. Tetarenko}, doi = {10.3847/1538-4357/adea41}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {131}, shortjournal = {The Astrophys. J.}, title = {Radio continuum studies of ultracompact and short orbital period X-ray binaries}, volume = {988}, year = {2025}, }
• (2025). Inferring kilonova ejecta photospheric properties from early blackbody spectra. ApJ, 988(1), 130. (www)

  @article{ , abstract = {We present simple analytic corrections to the standard blackbody fitting used for early kilonova emission. We consider a spherical, relativistically expanding shell that radiates thermally at a single temperature in its own rest frame. Due to relativistic effects, including Doppler boosting, time delay, and temperature evolution, the observed temperature is smeared across different polar angles by approximately ∼10%. While the observed spectrum remains roughly consistent with a single-temperature blackbody, neglecting relativistic effects leads to significant systematic inaccuracies: the inferred photospheric velocity and temperature are overestimated by up to ∼50% for mildly relativistic velocities. By applying our analytic corrections, these deviations are reduced to within 10%, even in cases where the photosphere is receding and cooling is considered. Applying our corrections to observed kilonovae (AT2017gfo and the thermal component of GRB 211211A) reveals that standard blackbody fitting overestimated the inferred velocities and temperatures by 10%–40%; such deviations can alter the inferred formation of heavy elements.}, archive = {J_ApJ}, author = {Gilad Sadeh}, doi = {10.3847/1538-4357/adecee}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {130}, shortjournal = {The Astrophys. J.}, title = {Inferring kilonova ejecta photospheric properties from early blackbody spectra}, volume = {988}, year = {2025}, }
• (2025). Using the coolest ae stars to constrain circumstellar disk viscosity. ApJ, 988(1), 129. (www)

  @article{ , abstract = {Classical Ae (CAe) stars are main-sequence, A-type stars with H α emission but no signature of dust. They are thought to be the cool extension of the classical Be stars to lower masses. Recent surveys based on H α spectroscopy have significantly increased the number of known CAe stars, with the population extending to spectral types as cool as A4 ( T eff ≈ 8500 K). We compute the temperature structure of gaseous, circumstellar disks around A-type stars, including both radiative heating from the central star and viscous shear heating from the disk’s rotation. We find that shear heating can become important for spectral types A2 and later and can act to increase the low temperatures predicted by purely radiatively heated disks. Our modeling indicates that the presence and strength of H α emission for spectral types A2 and later significantly increases with the amount of shear heating included, and we propose that this dependence can be used to constrain the α viscosity parameter appropriate for CAe star disks.}, archive = {J_ApJ}, author = {R. Anusha and T. A. A. Sigut}, doi = {10.3847/1538-4357/ade140}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {129}, shortjournal = {The Astrophys. J.}, title = {Using the coolest ae stars to constrain circumstellar disk viscosity}, volume = {988}, year = {2025}, }
• (2025). The age and high-energy environment of the very young transiting exoplanet TOI 1227b. ApJ, 988(1), 128. (www)

  @article{ , abstract = {The mid-M star TOI 1227 hosts among the youngest known transiting exoplanets. We have conducted new X-ray imaging and optical spectroscopic observations of TOI 1227 aimed at ascertaining its age and the influence of its high-energy radiation on the exoplanet, TOI 1227b. We obtained a definitive X-ray detection of TOI 1227 with the Chandra/High Resolution Camera-I (HRC-I), and measured its Li and H α lines using the Australian National University’s Siding Spring Observatory 2.3 m telescope (WiFeS) spectroscopy. Through spatiokinematic, isochronal, and spectral energy distribution-based modeling, we have constrained the age of TOI 1227 as lying between 5 and 12 Myr, with a best estimate of ∼8 Myr. In the context of this age, we model the evolution of the transiting exoplanet TOI 1227b, using the X-ray luminosity derived from Chandra HRC-I imaging. Our modeling suggests that TOI 1227b is currently undergoing rapid atmospheric mass loss at rates on the order of ∼10 12 g s −1 . The modeling demonstrates that the exoplanet’s predicted future evolution depends sensitively on assumptions for total and core planet mass, highlighting the importance of follow-up observations of the TOI 1227 star–exoplanet system to enable measurements of both planetary mass and mass-loss rate.}, archive = {J_ApJ}, author = {Attila Varga and Joel H. Kastner and Alexander S. Binks and Hans Moritz Günther and Simon J. Murphy}, doi = {10.3847/1538-4357/ade151}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {128}, shortjournal = {The Astrophys. J.}, title = {The age and high-energy environment of the very young transiting exoplanet TOI 1227b}, volume = {988}, year = {2025}, }
• (2025). Coevolution of dwarf galaxies and their circumgalactic medium across cosmic time. ApJ, 988(1), 127. (www)

  @article{ , abstract = {Dwarf galaxies (DGs) are thought of as the building blocks of large galaxies such as our Milky Way. This paper presents new high-resolution hydrodynamical simulations of DGs and their intergalactic medium with the GIZMO code. Our simulations consider the key physical processes of galaxy evolution, such as gas cooling, chemistry, and stellar and black hole feedback. Unlike previous work, the initial conditions of our simulations take DGs of 2–5 × 10 10 M ⊙ from the realistic cosmology simulations of IllustrisTNG . We further increase the original resolution of IllustrisTNG by a factor of ∼100 via a particle-splitting scheme. Our results show that the evolution of the complex multiphase circumgalactic medium (CGM) and its metal content is sensitive to the redshift of DGs. The accretion of the CGM into DGs plays a key role, providing 20%–50% of the star-forming gas and replenishing 40%–70% of the total mass in the galactic disk. Furthermore, the accretion histories of the supermassive black holes (SMBHs) at the centers of high- z DGs shows episodic patterns, with high-accreting states close to ∼10% of the Eddington mass accretion rate, implying the rapid growth of SMBHs in the early Universe, which may be revealed by coming observations from the James Webb Space Telescope.}, archive = {J_ApJ}, author = {Pei-Cheng Tung and Ke-Jung Chen}, doi = {10.3847/1538-4357/ade1d4}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {127}, shortjournal = {The Astrophys. J.}, title = {Coevolution of dwarf galaxies and their circumgalactic medium across cosmic time}, volume = {988}, year = {2025}, }
• (2025). Varstrometry for off-nucleus and dual sub-kpc AGN (VODKA): Long-slit optical spectroscopic follow-up with Gemini/GMOS and hubble space Telescope/STIS. ApJ, 988(1), 126. (www)

  @article{ , abstract = {High spatial and spectral resolution observations are essential for identifying subarcsecond dual and lensed quasars and confirming their redshifts. We present Gemini/Gemini Multi-Object Spectrograph and Hubble Space Telescope/STIS optical spectra for 27 dual quasar candidates selected based on their variability-induced astrometric noise or double detections in Gaia (the Varstrometry for Off-nucleus and Dual sub-Kpc AGN (VODKA) project). From this follow-up, we spectroscopically identify 11 star superpositions and seven dual/lensed quasars. Among the remaining targets, two are likely dual/lensed quasars based on additional radio imaging, while the rest are quasars with unknown companions. Without prior photometric or spectroscopic selection, we find the star contamination rate to be 41%–67%, while the dual/lensed quasar fraction is ≳26% in the follow-up VODKA sample. However, when combined with existing unresolved spectra and spatially resolved two-band color cuts, the dual/lensed quasar fraction can be increased to ≳67%. Our study highlights the need for high-quality spectral data, including a signal-to-noise ratio of at least 20, spatial resolution that is at least twice finer than the source separation, and a spectral resolution of R ≳ 1000, in order to separate close sources, exclude stellar superpositions, and reliably identify dual quasars.}, archive = {J_ApJ}, author = {Yu-Ching Chen and Arran C. Gross and Xin Liu and Yue Shen and Nadia L. Zakamska and Hsiang-Chih Hwang and Ming-Yang Zhuang}, doi = {10.3847/1538-4357/ade23b}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {126}, shortjournal = {The Astrophys. J.}, title = {Varstrometry for off-nucleus and dual sub-kpc AGN (VODKA): Long-slit optical spectroscopic follow-up with Gemini/GMOS and hubble space Telescope/STIS}, volume = {988}, year = {2025}, }
• (2025). The angular momentum of stars reflects the relationship between star-forming environment and galactic evolution history. ApJ, 988(1), 125. (www)

  @article{ , abstract = {This study focuses on stars with masses above the Kraft break in the Kepler field. Their rotational angular momenta are essentially the same as those at the zero-age main sequence. The angular momentum dissipation experienced by these stars during their pre-main sequence (PMS) phase is also relatively weak, so their rotational angular momentum can reflect the parameters of their parental molecular clouds. The reliability of angular momentum measurements was evaluated based on the phenomenon of angular momentum conservation observed in stars before and after the turnoff point in observational data. We find that stars with masses between 1.4 M ⊙ and 1.8 M ⊙ show an inverse proportionality between angular momentum and isochrone age. We propose that the angular momentum–age correlation reflects changes in the star-forming environment in the Milky Way’s history. Besides, the observed inverse proportionality implies that as the Milky Way has evolved, the stars formed within it tend to possess greater rotational angular momenta. This trend would promote the fragmentation of stars during the PMS phase and inhibit the formation of massive stars, providing a useful perspective for explaining variations in the initial mass function.}, archive = {J_ApJ}, author = {Yu-Fu Shen and Yan Xu and Yi-Bo Wang and Xiu-Lin Huang and Xing-Xing Hu and Qi Yuan}, doi = {10.3847/1538-4357/ade399}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {125}, shortjournal = {The Astrophys. J.}, title = {The angular momentum of stars reflects the relationship between star-forming environment and galactic evolution history}, volume = {988}, year = {2025}, }
• (2025). The rotating bulge and halo in the milky way: Evidence of angular momentum transferred from the decelerating bar. ApJ, 988(1), 124. (www)

  @article{ , abstract = {Recent observations indicate that both the Milky Way bulge and inner halo exhibit angular momentum, although the origin and evolution of this prograde signature remain ambiguous. One plausible scenario involves secular evolution induced by the central bar and spiral arms. In this study, we identified a component consisting of 1,175,737 stars with net rotation through the application of a neural network (NN) method. To investigate the composition of this rotating sample and the origin of its rotation, we conducted a test particle simulation incorporating an equilibrium axisymmetric background potential together with a central decelerating bar. The test particles were generated using a distribution function model derived from observational constraints. Our results indicate that the decelerating bar transfers angular momentum to the pseudo-stars, and the rotational profile from our simulation shows strong agreement with observational data. These findings suggest that the rotating sample identified by our NN model is predominantly comprised of bulge, halo, and thick disk stars, and that the central decelerating bar is pivotal in shaping the inner Galaxy’s kinematics through angular momentum transfer.}, archive = {J_ApJ}, author = {Zhuohan Li and Chengdong Li and Gang Zhao and Ruizhi Zhang and Xiang-Xiang Xue}, doi = {10.3847/1538-4357/ade430}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {124}, shortjournal = {The Astrophys. J.}, title = {The rotating bulge and halo in the milky way: Evidence of angular momentum transferred from the decelerating bar}, volume = {988}, year = {2025}, }
• (2025). Modified gravity realizations of quintom dark energy after DESI DR2. ApJ, 988(1), 123. (www)

  @article{ , abstract = {We investigate the realization of quintom scenario for dynamical dark energy within modified gravity theories that can efficiently fit the recent observational data sets. Starting from a general effective field theory formulation of dark energy in metric-affine geometry, we derive the background action in unitary gauge and we demonstrate how both f ( T ) and f ( Q ) gravity can naturally realize quintom behavior through appropriate forms and parameter choices. Additionally, using the Gaussian process reconstruction of the latest Dark Energy Spectroscopic Instrument DR2 baryon acoustic oscillation data combined with Type Ia supernovae and cosmic microwave background observations, we extract the reconstructed dark-energy equation-of-state parameter, showing that it exhibits quintom-type evolution, crossing the phantom divide from below. Moreover, through detailed parameter estimations and application of information criteria, we compare the model with the quadratic one and the ΛCDM model. Our results show that, due to its rich structure, modified gravity stands as one of the main candidates for the realization of the data-favored dynamical dark energy.}, archive = {J_ApJ}, author = {Yuhang Yang and Qingqing Wang and Xin Ren and Emmanuel N. Saridakis and Yi-Fu Cai}, doi = {10.3847/1538-4357/ade43f}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {123}, shortjournal = {The Astrophys. J.}, title = {Modified gravity realizations of quintom dark energy after DESI DR2}, volume = {988}, year = {2025}, }
• (2025). Breaking the degeneracy between warps and radial flows in external galaxies. ApJ, 988(1), 122. (www)

  @article{ , abstract = {Observations of the line-of-sight (LOS) component of emitter velocities in galaxies are valuable for reconstructing their two-dimensional (2D) velocity fields, albeit requiring certain assumptions. A common one is that radial flows can be neglected in the outer regions of galaxies, while their geometry can be deformed by a warp. A specular approach assumes that galactic disks are flat but allows for the presence of radial flows. This approach enables the reconstruction of 2D velocity maps that encompass both the transversal and radial velocity fields. Through the study of velocity fields in toy disk models, we find that the presence of warps is manifested as a dipolar correlation between the two velocity components obtained by assuming a flat disk. This shows that the analysis of angular velocity anisotropies provides an effective tool for breaking the degeneracy between warps and radial flows. We have applied these findings to the analysis of velocity fields of the galaxies from the THINGS sample and M33. Many of these galaxies exhibit such a dipolar correlation, indicating the presence of warps. However, we have found that the warp alone cannot explain all variations in the velocity field, suggesting that intrinsic perturbations are common. Furthermore, we have observed that the spatial distribution of the LOS velocity dispersion may correlate with both velocity components, providing independent evidence of nontrivial velocity fields. These findings offer a robust approach to reconstructing the velocity fields of galaxies, allowing us to distinguish between the presence of warps and complex velocity structures by assessing their relative amplitude.}, archive = {J_ApJ}, author = {Francesco Sylos Labini and Giordano De Marzo and Matteo Straccamore}, doi = {10.3847/1538-4357/adc71c}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {122}, shortjournal = {The Astrophys. J.}, title = {Breaking the degeneracy between warps and radial flows in external galaxies}, volume = {988}, year = {2025}, }
• (2025). He awa whiria: The tidal streams of interstellar objects. ApJ, 988(1), 121. (www)

  @article{ , abstract = {Upcoming surveys are likely to discover a new sample of interstellar objects (ISOs) within the solar system, but questions remain about the origin and distribution of this population within the Galaxy. ISOs are ejected from their host systems with a range of velocities, spreading out into tidal streams—analogous to the stellar streams routinely observed from the disruption of star clusters and dwarf galaxies. We create a simulation of ISO streams orbiting in the Galaxy, deriving a simple model for their density distribution over time. We then construct a population model to predict the properties of the streams in which the Sun is currently embedded. We find that the number of streams encountered by the Sun is quite large, ∼10 6 or more. However, the wide range of stream properties means that for reasonable future samples of ISOs observed in the solar system, we may see ISOs from the same star (“siblings”), and we are likely to see ISOs from the same star cluster (“cousins”). We also find that ISOs are typically not traceable to their parent star, though this may be possible for ISO siblings. Any ISOs observed with a common origin will come from younger, dynamically colder streams.}, archive = {J_ApJ}, author = {John C. Forbes and Michele T. Bannister and Chris Lintott and Angus Forrest and Simon Portegies Zwart and Rosemary C. Dorsey and Leah Albrow and Matthew J. Hopkins}, doi = {10.3847/1538-4357/adc9ac}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {121}, shortjournal = {The Astrophys. J.}, title = {He awa whiria: The tidal streams of interstellar objects}, volume = {988}, year = {2025}, }
• (2025). X-ray spectral variability as a probe of multimessenger emission in blazar 5BZB j0630−2406. ApJ, 988(1), 120. (www)

  @article{ , abstract = {X-ray observations are essential for understanding the multimessenger emission mechanisms of active galactic nuclei (AGN). Blazars, a subset of AGN whose X-ray emission predominantly originates from relativistic jets, have been proposed as promising high-energy neutrino sources. In this work, we study the candidate neutrino-emitting blazar 5BZB J0630-2406, which has been observed over multiple epochs with the XMM-Newton, NuSTAR, Neil Gehrels Swift-XRT, and eROSITA observatories. Analysis of the X-ray spectra in the 2.0–10.0 keV band shows significant variability, with high-flux states adhering to a power-law model indicative of jet emission. However, during low-flux states, the spectrum reveals an additional component in hard X-rays, indicating a transition from jet-dominated to multicomponent X-ray emission, possibly associated with hadronic processes. To investigate this spectral evolution, we tested various models and found it to be consistent with coronal emission or photoionized absorption processes typically observed in obscured AGN. The identification of the X-ray spectral variability in 5BZB J0630-2406, combined with its potential for neutrino production, opens new perspectives in multimessenger astrophysics of blazars, highlighting the synergies between the mechanisms of the jet and the nuclear environment.}, archive = {J_ApJ}, author = {Jose Maria Sanchez Zaballa and Sara Buson and Stefano Marchesi and Francesco Tombesi and Thomas Dauser and Joern Wilms and Alessandra Azzollini}, doi = {10.3847/1538-4357/addfd2}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {120}, shortjournal = {The Astrophys. J.}, title = {X-ray spectral variability as a probe of multimessenger emission in blazar 5BZB j0630−2406}, volume = {988}, year = {2025}, }
• (2025). Kinetic simulation of magnetic reconnection with pickup ions: Shell stability and reconnection rate analysis. ApJ, 988(1), 119. (www)

  @article{ , abstract = {Collisionless magnetic reconnection is postulated to be active in many regions of the heliosphere, where the physics and formation of heliospheric structures are influenced by pickup ions (PUIs). Recent investigations suggest that the presence of PUIs may enhance the reconnection rate due to PUI-induced turbulence. Our investigation from particle-in-cell simulations with seed PUI shell velocity distributions reveals that the distributions remain quasi-stable within the reconnection exhaust region. The reconnection rate is rather suppressed as compared with non-PUI reconnection simulations. The PUI population eventually responds to the reconnection dynamics and forms a thicker current sheet layer. Both PUI and regular ion populations develop sub-ion-Alfvénic outflow jets, although PUI outflows are slower in comparison and extend beyond the separatrix surface. We predict that a future Interstellar Probe mission may encounter reconnecting current sheet layers in the outer heliosphere that demonstrate an initial slow modulation followed by a sharp rotation of the reconnecting magnetic field toward the center of the layer.}, archive = {J_ApJ}, author = {P. S. Pyakurel and M. Swisdak and S. Eriksson and B. L. Shrestha and Y.-H. Liu and J. M. TenBarge and M. A. Shay and T. D. Phan}, doi = {10.3847/1538-4357/ade3db}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {119}, shortjournal = {The Astrophys. J.}, title = {Kinetic simulation of magnetic reconnection with pickup ions: Shell stability and reconnection rate analysis}, volume = {988}, year = {2025}, }
• (2025). Forecasting geomagnetic disturbances in solar cycle 25 for space weather prediction. ApJ, 988(1), 118. (www)

  @article{ , abstract = {Accurate forecasting of geomagnetic disturbances is essential for mitigating space weather effects on critical infrastructure. We present an optimized Long Short-term Memory neural network (LSTM+), refined through a reforecast procedure and hyperparameter tuning using data from Solar Cycle 24, achieving high predictive skill. For Solar Cycle 24, the model demonstrates a Nash–Sutcliffe efficiency of 0.95 for Ap and 0.78 for Dst, with Pearson correlation coefficients of 0.983 and 0.901, respectively. Furthermore, the error rate for predicting the peak Ap and trough Dst values was low, at 4.16% and 7.77%, respectively. This LSTM+ model is used to predict the Ap and Dst indices for Solar Cycle 25. The model forecasts a peak in Ap around 2026 January and a trough in Dst around 2026 February, consistent with the observed lag of up to 3 yr between geomagnetic indices and the sunspot number maximum in prior cycles. Validation against historical data confirms the model’s reliability in capturing these temporal offsets. These projections offer a predictive framework for improving space weather preparedness and safeguarding technological systems.}, archive = {J_ApJ}, author = {Mu He and Hongbing Zhu}, doi = {10.3847/1538-4357/ade7fd}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {118}, shortjournal = {The Astrophys. J.}, title = {Forecasting geomagnetic disturbances in solar cycle 25 for space weather prediction}, volume = {988}, year = {2025}, }
• (2025). The peak flux of long gamma-ray bursts in the Ep,i–Liso diagram and in the classification. ApJ, 988(1), 117. (www)

  @article{ , abstract = {The E p,i – L iso correlation of long gamma-ray bursts (LGRBs) is regarded as a fundamental correlation for standardizing LGRBs to probe cosmology and constrain LGRB physics. However, this correlation may be affected by potential selection effects, which are likely overlooked in the current small LGRB redshift sample. In this work, we simulate a large LGRB sample that reflects the observed situation, aiming to study the impact of peak flux P on the observed LGRB E p,i – L iso correlation. We find that the overall E p,i and L iso distribution, which will directly affect the best-fit result of the correlation, is significantly dependent on the value of P . This indicates that the impact of peak flux selection should be carefully considered in the studies and applications of the E p,i – L iso correlation. Notably, we show that our simulated data can reproduce the observed P distribution only if some dependence between E p,i and L iso is included in the simulation. This is an indication that the E p,i – L iso connection is a crucial property of LGRBs. We also find that GRBs with high peak flux in the low- E p,i and L iso region are not the straightforward extrapolation of the GRB population in the higher- E p,i and L iso region. Selecting four bursts with L iso ≤ 10 50 erg s −1 , E p,i ≤ 10 2.5 keV, and P ≥ 10 0.5 ph cm −2 s −1 , we find two bursts, GRB 060614 and GRB 191019A, which may not be associated with the theoretical massive-star origin of LGRBs. This suggests that combining P with the position in the E p,i – L iso diagram may be used to indicate alternative LGRB origins.}, archive = {J_ApJ}, author = {Guangxuan Lan and Jean-Luc Atteia}, doi = {10.3847/1538-4357/ade804}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {117}, shortjournal = {The Astrophys. J.}, title = {The peak flux of long gamma-ray bursts in the Ep,i–Liso diagram and in the classification}, volume = {988}, year = {2025}, }
• (2025). Detecting atmospheric CO2 trends as population-level signatures for long-term stable water oceans and biotic activity on temperate terrestrial exoplanets. ApJ, 988(1), 116. (www)

  @article{ , abstract = {Identifying key observables is essential for enhancing our knowledge of exoplanet habitability and biospheres, as well as improving future mission capabilities. While currently challenging, future observatories such as the Large Interferometer for Exoplanets (LIFE) will enable atmospheric observations of a diverse sample of temperate terrestrial worlds. Using thermal emission spectra that represent conventional predictions of atmospheric CO 2 variability across the habitable zone (HZ), we assess the ability of the LIFE mission—as a specific concept for a future space-based interferometer—to detect CO 2 trends indicative of the carbonate–silicate (Cb–Si) weathering feedback, a well-known habitability marker and potential biological tracer. Therefore, we explore the feasibility of differentiating between CO 2 trends in biotic and abiotic planet populations. We create synthetic exoplanet populations based on geochemistry-climate predictions and perform retrievals on simulated thermal emission observations. The results demonstrate the robust detection of population-level CO 2 trends in both biotic and abiotic scenarios for population sizes as small as 30 exo-Earth candidates (EECs) and the lowest assessed spectrum quality in terms of signal-to-noise ratio, S/N = 10, and spectral resolution, R = 50. However, biased CO 2 partial pressure constraints hinder accurate differentiation between biotic and abiotic trends. If these biases were corrected, accurate differentiation could be achieved for populations with ≥100 EECs. We conclude that LIFE can effectively enable population-level characterization of temperate terrestrial atmospheres and detect CO 2 trends driven by the Cb–Si cycle as habitability indicators. Nevertheless, the identified biases underscore the importance of testing atmospheric characterization performance against the broad diversity expected for planetary populations.}, archive = {J_ApJ}, author = {Janina Hansen and Daniel Angerhausen and Sascha P. Quanz and Derek Vance and Björn S. Konrad and Emily O. Garvin and Eleonora Alei and Jens Kammerer and Felix A. Dannert}, doi = {10.3847/1538-4357/addc6e}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {116}, shortjournal = {The Astrophys. J.}, title = {Detecting atmospheric CO2 trends as population-level signatures for long-term stable water oceans and biotic activity on temperate terrestrial exoplanets}, volume = {988}, year = {2025}, }
• (2025). Detection of multiple X-ray quasi-periodic oscillations in IGR j19294+1816 with insight-HXMT. ApJ, 988(1), 115. (www)

  @article{ , abstract = {We report the timing results with Insight-HXMT observations of X-ray binary IGR J19294+1816 during its 2019 type I outburst at the decline phase shortly following its peak. We analyze the light curves and power density spectrum of the 2019 observations and reveal a peak at ν NS ∼ 80.2 mHz, corresponding to X-ray pulsations from the neutron star. In addition, a significant quasi-periodic oscillation (QPO) feature is observed at ν QPO ∼ 30.2 mHz from 10 to 50 keV, with the rms amplitude increasing with energy. Furthermore, we detect two QPOs at frequencies of ∼51.1 and 113.7 mHz (corresponding to sidebands near ν NS ± ν QPO ) in the range 25–50 keV, exhibiting an rms amplitude of around 12%. Wavelet analysis also shows multiple QPOs at the frequencies of ∼30 mHz, 50 and 110 mHz, which have transient behaviors. The centroid frequencies of ∼30 mHz remain nearly constant for different luminosities. Our research identifies IGR J19294+1816 as the second strong magnetic field pulsar with significant sideband signals around the spin frequency. We explore various physical origins that could explain the presence of multiple QPOs.}, archive = {J_ApJ}, author = {Wen Yang and Wei Wang}, doi = {10.3847/1538-4357/ade238}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {115}, shortjournal = {The Astrophys. J.}, title = {Detection of multiple X-ray quasi-periodic oscillations in IGR j19294+1816 with insight-HXMT}, volume = {988}, year = {2025}, }
• (2025). SPINN: Advancing cosmological simulations of fuzzy dark matter with physics informed neural networks. ApJ, 988(1), 114. (www)

  @article{ , abstract = {Physics-informed neural networks (PINNs) have emerged as a powerful tool for solving differential equations by integrating physical laws into the learning process. This work leverages PINNs to simulate gravitational collapse, a critical phenomenon in astrophysics and cosmology. We introduce the Schrödinger–Poisson (SP) informed neural network which solves the nonlinear SP equations to simulate the gravitational collapse of fuzzy dark matter (FDM) in both 1D and 3D settings. The results demonstrate accurate predictions of key metrics such as mass conservation, density profiles, and structure suppression, validating against known analytical or numerical benchmarks. This work highlights the potential of PINNs for efficient, possibly scalable modeling of FDM and other astrophysical systems, overcoming the challenges faced by traditional numerical solvers due to the nonlinearity of the involved equations and the necessity to resolve multiscale phenomena, especially resolving the fine wave features of FDM on cosmological scales.}, archive = {J_ApJ}, author = {Ashutosh K. Mishra and Emma Tolley}, doi = {10.3847/1538-4357/ade43e}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {114}, shortjournal = {The Astrophys. J.}, title = {SPINN: Advancing cosmological simulations of fuzzy dark matter with physics informed neural networks}, volume = {988}, year = {2025}, }
• (2025). Precise age for the binary HD 21278 in the young α persei cluster. ApJ, 988(1), 113. (www)

  @article{ , abstract = {We present a study of the double-lined spectroscopic binary HD 21278 that contains one of the brightest main-sequence stars in the young α Persei open cluster. We analyzed new spectra and reanalyzed archived spectra to measure precise new radial velocity curves for the binary. We also obtained interferometric data using the CHARA Array at Mount Wilson to measure the sky positions of the two stars and the inclination of the ∼2 mas orbit. We determine that the two stars have masses of 5.381 ± 0.084 M ⊙ and 3.353 ± 0.064 M ⊙ . From isochrone fits, we find the cluster’s age to be 49  ±  7 Myr (using PARSEC models) or 49.5 ± 6 Myr (MIST models). Finally, we revisit the massive white dwarfs that are candidate escapees from the α Persei cluster to try to better characterize the massive end of the white dwarf initial–final mass relation. The implied progenitor masses challenge the idea that Chandrasekhar-mass white dwarfs are made by single stars with masses near 8 M ⊙ .}, archive = {J_ApJ}, author = {Christopher A. Danner and Eric L. Sandquist and Gail H. Schaefer and Luigi R. Bedin and Christopher D. Farrington and Cyprien Lanthermann and Stefan Kraus and Robert Klement and Narsireddy Anugu and John D. Monnier and Jerome A. Orosz and Isabelle Codron and Tyler Gardner and Mayra Gutierrez and Benjamin R. Setterholm and Jeremy Jones and Becky Flores}, doi = {10.3847/1538-4357/ade0bb}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {113}, shortjournal = {The Astrophys. J.}, title = {Precise age for the binary HD 21278 in the young α persei cluster}, volume = {988}, year = {2025}, }
• (2025). A comprehensive light-curve model of the very fast nova v1674 herculis. ApJ, 988(1), 112. (www)

  @article{ , abstract = {V1674 Her is one of the fastest novae, of which the very early phase is well observed, including optical rise to the peak over 10 mag. We present a full theoretical light-curve model of V1674 Her. Our 1.35 M ⊙ white dwarf (WD) model with the mass accretion rate of 1 × 10 −11 M ⊙ yr −1 explains overall properties including a very fast rise and decay of the optical V light curve. The WD photosphere expands up to 21 R ⊙ , thus a 0.26 M ⊙ companion star orbiting the WD every 3.67 hr is engulfed 2.7 hr after the onset of thermonuclear runaway and appears 5.3 days after that. The duration of X-ray flash is only 0.96 hr. The evolution of the expanding envelope and temporal change of the photospheric radius are very consistent with observed optical and X-ray modulations with the orbital and spin (501 s) periods. We confirm that the decay phase of the nova light curve is well approximated by a sequence of steady-state envelope solutions. Using the time-stretching method of nova light curves, we obtain the V -band distance modulus of ( m − M ) V = 16.3 ± 0.2 and determine the distance to be d = 8.9 ± 1 kpc for the interstellar extinction of E ( B – V ) = 0.5 ± 0.05.}, archive = {J_ApJ}, author = {Mariko Kato and Izumi Hachisu and Hideyuki Saio}, doi = {10.3847/1538-4357/ade231}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {112}, shortjournal = {The Astrophys. J.}, title = {A comprehensive light-curve model of the very fast nova v1674 herculis}, volume = {988}, year = {2025}, }
• (2025). The detection of spatially resolved protostellar outflows and episodic jets in the outer galaxy. ApJ, 988(1), 111. (www)

  @article{ , abstract = {We present the first detection of spatially resolved protostellar outflows and jets in the outer Galaxy. We observed five star-forming regions in the outer Galaxy (Sh 2-283 and NOMF05-16/19/23/63; galactocentric distance = 15.7–17.4 kpc) with the Atacama Large Millimeter/submillimeter Array. Toward Sh 2-283, we have detected distinct outflow (∼5–50 km s −1 ) and jet components (∼50–100 km s −1 ) associated with the protostar in CO(3–2) emission. The outflows and jets are well collimated, with the jets exhibiting multiple bullet structures. The position–velocity diagram along the CO flow axis shows two characteristic structures: (a) the flow velocity, which linearly increases with the position offset from the core center (the Hubble-like flow); and (b) the continuous velocity components of the periodical flows (spine-like structures), which may indicate episodic mass ejection events. The time intervals of the mass ejection events are estimated to be 900–4000 yr, based on the slopes of these spine-like structures. These characteristics align with those of nearby protostellar systems, indicating that early star formation in low-metallicity environments, such as the outer Galaxy, resembles that in the inner Galaxy. In contrast to the physical similarities, the N (SiO)/ N (CO) ratio in the jet bullet appears to be lower than that measured in the low-mass protostellar sources in the inner Galaxy. This may indicate a different shock chemistry or different dust composition in the outer Galaxy source, although non–local thermodynamic equilibrium effects could also affect the observed low N (SiO)/ N (CO) ratio. We also report the new detection of four other outflow sources in the outer Galaxy.}, archive = {J_ApJ}, author = {Toki Ikeda and Takashi Shimonishi and Natsuko Izumi and Hiroyuki Kaneko and Satoko Takahashi and Kei E. I. Tanaka and Kenji Furuya and Chikako Yasui}, doi = {10.3847/1538-4357/ade235}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {111}, shortjournal = {The Astrophys. J.}, title = {The detection of spatially resolved protostellar outflows and episodic jets in the outer galaxy}, volume = {988}, year = {2025}, }
• (2025). The emerging black hole mass function in the high-redshift universe. ApJ, 988(1), 110. (www)

  @article{ , abstract = {Observations with the James Webb Space Telescope (JWST) have identified an abundant population of supermassive black holes (SMBHs) already in place during the first few hundred million years of cosmic history. Most of them appear overmassive relative to the stellar mass in their host systems, challenging models of early black hole seeding and growth. Multiple pathways exist to explain their formation, including heavy seeds formed from direct collapse/supermassive stars or sustained super-Eddington accretion onto light stellar remnant seeds. We use the semianalytical code Ancient Stars and Local Observables by Tracing Halos to predict the emerging SMBH mass function under physically motivated models for both light- and heavy-seed formation, to be compared with upcoming ultradeep JWST surveys. We find that both pathways can reproduce observations at z ∼ 5–6, but have distinct features at higher redshifts of z ∼ 10. Specifically, JWST observations have the potential to constrain the fraction of efficiently accreting (super-Eddington) SMBHs, as well as the existence and prevalence of heavy seeds, in particular through ultradeep observations of blank fields and/or gravitational lensing surveys. Such observations will provide key insights to understand the process of SMBH formation and evolution during the emergence of the first galaxies. We further emphasize the great promise of possible SMBH detections at z ≳ 15 with future JWST observations to break the degeneracy between light- and heavy-seed models.}, archive = {J_ApJ}, author = {Junehyoung Jeon and Boyuan Liu and Anthony J. Taylor and Vasily Kokorev and John Chisholm and Dale D. Kocevski and Steven L. Finkelstein and Volker Bromm}, doi = {10.3847/1538-4357/ade2e1}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {110}, shortjournal = {The Astrophys. J.}, title = {The emerging black hole mass function in the high-redshift universe}, volume = {988}, year = {2025}, }
• (2025). Comprehensive radio monitoring of the black hole X-ray binary swift j1727.8−1613 during its 2023–2024 outburst. ApJ, 988(1), 109. (www)

  @article{ , abstract = {This work presents comprehensive multifrequency radio monitoring of the black hole low-mass X-ray binary (LMXB) Swift J1727.8−1613, which underwent its first recorded outburst after its discovery in 2023 August. Through a considerable community effort, we have coalesced the data from multiple, distinct observing programs; the light curves include ∼10 months and 197 epochs of monitoring from seven radio facilities with observing frequencies ranging from (approximately) 0.3–230 GHz. The primary purpose of this work is to provide the broader astronomical community with these light curves to assist with the interpretation of other observing campaigns, particularly nonradio observing frequencies. We discuss the phenomenological evolution of the source, which included (i) multiple radio flares consistent with the launching of discrete jet ejections, the brightest of which reached ∼1 Jy; (ii) temporally evolving radio spectral indices ( α ), reaching values steeper than expected for optically thin synchrotron emission ( α < −1) and emission with significant radiative cooling ( α < −1.5). We have published a digital copy of the data and intend for this work to set a precedent for the community to continue releasing comprehensive radio light curves of future LMXB outbursts.}, archive = {J_ApJ}, author = {Andrew K. Hughes and Francesco Carotenuto and Thomas D. Russell and Alexandra J. Tetarenko and James C. A. Miller-Jones and Arash Bahramian and Joe S. Bright and Fraser J. Cowie and Rob Fender and Mark A. Gurwell and Jasvinderjit K. Khaulsay and Anastasia Kirby and Serena Jones and Elodie Lescure and Michael McCollough and Richard M. Plotkin and Ramprasad Rao and Saeqa D. Vrtilek and David R. A. Williams-Baldwin and Callan M. Wood and Gregory R. Sivakoff and Diego Altamirano and Piergiorgio Casella and Stéphane Corbel and David R. DeBoer and Melania Del Santo and Constanza Echiburú-Trujillo and Wael Farah and Poshak Gandhi and Karri I. I. Koljonen and Thomas Maccarone and James H. Matthews and Sera B. Markoff and Alexander W. Pollak and David M. Russell and Payaswini Saikia and Noel Castro Segura and Aarran W. Shaw and Andrew Siemion and Roberto Soria and John A. Tomsick and Jakob van den Eijnden}, doi = {10.3847/1538-4357/ade2e6}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {109}, shortjournal = {The Astrophys. J.}, title = {Comprehensive radio monitoring of the black hole X-ray binary swift j1727.8−1613 during its 2023–2024 outburst}, volume = {988}, year = {2025}, }
• (2025). Mother’s day superstorms: Pre- and post-storm evolutionary patterns of ARs 13664/8. ApJ, 988(1), 108. (www)

  @article{ , abstract = {In the week including Mother’s Day 2024, active region (AR) 13664 became superactive when AR 13668 emerged nearby, causing multiple X-class flares and coronal mass ejections, and an increase in activity level similar to that inferred from geomagnetic storms associated with the historic 1859 events. By analyzing both global warped toroids on which the active regions are strung, and active-region-scale magnetic flux and helicity, we find (i) the north and south toroids have nearly identical warped patterns, with mostly longitudinal wave numbers m = 1–3; (ii) in three longitude intervals the north and south toroids were tipped away from each other in latitude, with a longitude phase shift between them, creating locations most prone to AR eruptions; (iii) on an active region scale, vector magnetic fields deviate far from potential fields, and therefore contain large amounts of magnetic “free energy” available for conversion into kinetic energy and high-temperature radiation; (iv) the positive and negative polarities converge toward each other, facilitating reconnection and magnetic energy release; and (v) rapid changes in magnetic helicity, caused by helicity injection from below that creates helicity imbalances. Despite the coarser resolution of GONG magnetograms, the derived global toroids are strikingly similar to those derived from the Solar Dynamics Observatory's Helioseismic and Magnetic Imager. We conclude that the Mother’s Day superstorms were caused by enhanced magnetic complexity occurring due to intricate interactions among multiple active regions emerging at nearly the same locations. This suggests that predicting the locations of magnetically complex active regions, and studying and tracking their eruptive states using different proxy parameters can greatly improve our ability to forecast intense storms, not only hours but potentially weeks in advance.}, archive = {J_ApJ}, author = {Mausumi Dikpati and Marianna B. Korsós and Aimee A. Norton and Breno Raphaldini and Kiran Jain and Scott W. McIntosh and Peter A. Gilman and Andre S. W. Teruya and Nour E. Raouafi}, doi = {10.3847/1538-4357/addd09}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {108}, shortjournal = {The Astrophys. J.}, title = {Mother’s day superstorms: Pre- and post-storm evolutionary patterns of ARs 13664/8}, volume = {988}, year = {2025}, }
• (2025). Modeling YSO jets in 3D i: Highly variable asymmetric magnetic pressure-driven jets in the polar cavity from toroidal fields generated by inner disk accretion. ApJ, 988(1), 107. (www)

  @article{ , abstract = {Jets and outflows are commonly observed in young stellar objects, yet their origins remain debated. Using 3D nonideal magnetohydrodynamic (MHD) simulations of a circumstellar disk threaded by a large-scale open poloidal magnetic field, we identify three components in the disk-driven outflow: (1) a fast, collimated jet, (2) a less collimated, slower laminar disk wind, and (3) a magneto-rotational instability (MRI)-active turbulent disk wind that separates the former two. At high altitudes, the MRI-active wind merges with the laminar disk wind, leaving only the jet and disk wind as distinct components. The jet is powered by a novel mechanism in the star formation context: a lightly mass-loaded outflow driven by toroidal magnetic pressure in the low-density polar funnel near the system’s rotation axis. A geometric analysis of the magnetic field structure confirms that magnetic tension does not contribute to the outflow acceleration, with magnetic pressure acting as the dominant driver. While the outflow in our model shares similarities with the magneto-centrifugal model—such as angular momentum extraction from the accreting disk—centrifugal forces play a negligible role in jet acceleration. In particular, the flow near the jet base does not satisfy the conditions for magneto-centrifugal wind launching. Additionally, the jet in our simulation exhibits strong spatial and temporal variability. These differences challenge the applicability of rotation–outflow velocity relations derived from steady-state, axisymmetric magneto-centrifugal jet models for estimating the jet’s launching radius. For the slower disk wind, vertical motion is driven by toroidal magnetic pressure, while centrifugal forces widen the wind’s opening angle.}, archive = {J_ApJ}, author = {Yisheng Tu and Zhi-Yun Li and Zhaohuan Zhu and Chun-Yen Hsu and Xiao Hu}, doi = {10.3847/1538-4357/addf3c}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {107}, shortjournal = {The Astrophys. J.}, title = {Modeling YSO jets in 3D i: Highly variable asymmetric magnetic pressure-driven jets in the polar cavity from toroidal fields generated by inner disk accretion}, volume = {988}, year = {2025}, }
• (2025). Grand design spiral arms in the compact, embedded protoplanetary disk of haro 6-13. ApJ, 988(1), 106. (www)

  @article{ , abstract = {Millimeter continuum spiral arms have so far only been detected in a handful of protoplanetary disks, and thus we have a limited understanding of the circumstances in which they can form. In particular, substructures in small disks ( R ⪅ 50 au) have not been well characterized in comparison with large disks. We present Atacama Large Millimeter/submillimeter Array 1.3 mm continuum observations of the disk around the T Tauri star Haro 6-13 at a resolution of \sim 0\mathop{.}\limits^{^{\prime\prime} }04 (∼5 au). A pair of low-contrast spiral arms are detected at disk radii from ∼10 to 35 au. They can be approximated as Archimedean spirals with pitch angles ranging from ∼10° to 30°. The low value of the disk-averaged spectral index between 1.3 and 3 mm ( α = 2.1) and the high brightness temperatures suggest that the millimeter continuum is likely optically thick and thus may hide sufficient mass for the disk to become gravitationally unstable and form spiral arms. CO observations have shown that Haro 6-13 is surrounded by an envelope, raising the possibility that infall is facilitating spiral arm formation.}, archive = {J_ApJ}, author = {Jane Huang and Masataka Aizawa and Jaehan Bae and Sean M. Andrews and Myriam Benisty and Edwin A. Bergin and Stefano Facchini and Christian Ginski and Michael Küffmeier}, doi = {10.3847/1538-4357/ade1d8}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {106}, shortjournal = {The Astrophys. J.}, title = {Grand design spiral arms in the compact, embedded protoplanetary disk of haro 6-13}, volume = {988}, year = {2025}, }
• (2025). Investigating the anticorrelation between photon index and flux of the crab using RXTE and NuSTAR. ApJ, 988(1), 105. (www)

  @article{ , abstract = {We present a systematic study of the recently reported anticorrelation between X-ray flux and photon index (Γ) in the Crab Nebula, using archival Rossi X-Ray Timing Explorer (RXTE) Proportional Counter Array (3–50 keV), RXTE High Energy X-ray Timing Experiment (HEXTE; 20–100 keV), and Nuclear Spectroscopic Telescope Array (3–78 keV) observations. Spectra were extracted in soft (3–10 keV) and hard bands (10–50, 10–78, 20–100 keV) and fitted with an absorbed power-law model. Across all instruments and energy ranges, we confirm the existence of a persistent negative correlation–harder spectra at higher flux levels. The correlation is stronger in the hard bands compared to the soft bands. This is consistent with synchrotron emission modulated by magnetic-field variations in the pulsar wind nebula.}, archive = {J_ApJ}, author = {Debjit Chatterjee and Hsiang-Kuang Chang and Dipak Debnath and Koothodil Abhijith Augustine and Tzu-Hsuan Lin}, doi = {10.3847/1538-4357/ade9bd}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {105}, shortjournal = {The Astrophys. J.}, title = {Investigating the anticorrelation between photon index and flux of the crab using RXTE and NuSTAR}, volume = {988}, year = {2025}, }
• (2025). Searching for axion dark matter gegenschein of the vela supernova remnant with FAST. ApJ, 988(1), 104. (www)

  @article{ , abstract = {Axions are one of the leading dark matter candidates. If we are embedded in a Milky Way dark matter halo comprised of axions, their stimulated decay would enable us to observe a counterimage (“axion gegenschein”) with a frequency equal to half the axion mass in the opposite direction of a bright radio source. This spectral line emission will be broadened to Δ ν / ν ∼ σ d / c ∼ 10 −3 due to the velocity dispersion of dark matter, σ d . In this pilot study, we perform the first search for the expected axion gegenschein image of Vela supernova remnant with 26.4 hr of effective ON–OFF data from the Five-hundred-meter Aperture Spherical radio Telescope (FAST) L -band (1.0–1.5 GHz) 19 beam receiver. Our null detection limits the axion–photon coupling strength to be g aγγ ≲ 2 × 10 −10 GeV −1 in the mass ranges of 8.7 μ eV ≤ m a ≤ 9.44 μ eV and 10.85 μ eV ≤ m a ≤ 12.01 μ eV. These results provide a stronger constraint on g aγγ in this axion mass range than the current limits obtained by the direct search of an axion decay signal from a dwarf galaxy that uses FAST observations, but are a factor of ∼3 times weaker than the current CERN Axion Solar Telescope limit. Based on our observation strategy, data processing methods, and results, the expected sensitivity will reach ∼10 −11 GeV −1 with ∼2000 hr of observation in the future.}, archive = {J_ApJ}, author = {Wenxiu Yang and Yitian Sun and Yougang Wang and Katelin Schutz and Yichao Li and Calvin Leung and Wenkai Hu and Shuanghao Shu and Kiyoshi Masui and Xuelei Chen}, doi = {10.3847/1538-4357/adde48}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {104}, shortjournal = {The Astrophys. J.}, title = {Searching for axion dark matter gegenschein of the vela supernova remnant with FAST}, volume = {988}, year = {2025}, }
• (2025). Lyα radiative transfer modeling for 163 MUSE lyα-emitting galaxies at z = 3–6. ApJ, 988(1), 103. (www)

  @article{ , abstract = {We utilized Ly α radiative transfer calculations from H. Song et al. to investigate the properties of extended Ly α halos around star-forming galaxies in the Hubble Ultra Deep Field, observed by the Multi-Unit Spectroscopic Explorer. Expanding on the work of H. Song et al., which was limited to eight galaxies, we derived best-fit models for a significantly larger sample of 163 galaxies, which successfully reproduced both their Ly α spectra and surface brightness profiles (SBPs). These best-fit models suggest a broad medium distribution surrounding each galaxy, with low expanding velocities at large radii. This conclusion could not have been drawn from modeling either the spectrum or SBP alone, but only through simultaneous modeling of both. Our correlation analysis between observables and model parameters reveals that the spatial extent of Ly α halos is primarily determined by the extents of the medium and the source, while the spectral peak shift and full width at half maximum are governed mainly by optical depth, with the velocity structure of the medium playing a secondary yet nonnegligible role. The fact that various correlations derived from the full set of models and those from the best-fit subset can differ significantly highlights the complex and interdependent nature of Ly α radiative transfer. All model parameters interact to shape the observed Ly α features in a nontrivial way.}, archive = {J_ApJ}, author = {Sangeun Yu and Hyunmi Song and Kwang-Il Seon}, doi = {10.3847/1538-4357/ade2da}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {103}, shortjournal = {The Astrophys. J.}, title = {Lyα radiative transfer modeling for 163 MUSE lyα-emitting galaxies at z = 3–6}, volume = {988}, year = {2025}, }
• (2025). On convective turnover times and dynamos in low-mass stars. ApJ, 988(1), 102. (www)

  @article{ , abstract = {The relationship between magnetic activity and Rossby number is one way through which stellar dynamos can be understood. Using measured rotation rates and X-ray to bolometric luminosity ratios of an ensemble of stars, we derive empirical convective turnover times based on recent observations and reevaluate the X-ray activity–Rossby number relationship. In doing so, we find a sharp rise in the convective turnover time for stars in the mass range of 0.35−0.4 M ⊙ , associated with the onset of a fully convective internal stellar structure. Using MESA stellar evolution models, we infer the location of dynamo action implied by the empirical convective turnover time. The empirical convective turnover time is found to be indicative of dynamo action deep within the convective envelope in stars with masses 0.1–1.2 M ⊙ , crossing the fully convective boundary. Our results corroborate past works suggesting that partially and fully convective stars follow the same activity–Rossby relation, possibly owing to similar dynamo mechanisms. Our stellar models also give insight into the dynamo mechanism. We find that empirically determined convective turnover times correlate with properties of the deep stellar interior. These findings are in agreement with global dynamo models that see a reservoir of magnetic flux accumulates deep in the convection zone before buoyantly rising to the surface.}, archive = {J_ApJ}, author = {Seth Gossage and Rocio Kiman and Kristina Monsch and Amber A. Medina and Jeremy J. Drake and Cecilia Garraffo and Yuxi(Lucy) Lu and Joshua D. Wing and Nicholas J. Wright}, doi = {10.3847/1538-4357/adde4d}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {102}, shortjournal = {The Astrophys. J.}, title = {On convective turnover times and dynamos in low-mass stars}, volume = {988}, year = {2025}, }
• (2025). Saturns, but not super-jupiters, occur more frequently in the presence of inner super-earths. ApJ, 988(1), 101. (www)

  @article{ , abstract = {Studies from recent years have reached different conclusions regarding how frequently super-Earths are accompanied by long-period giant planets and vice versa. This relation has been predicted to be mass dependent by planet-formation models. We investigate that as the origin of the discrepancy using a radial velocity sample: the California Legacy Survey. We perform detection completeness corrections in order to discard detection bias as a possible explanation to our results. After bias corrections, we find that cold Jupiters are 5.6{5}_{-2.57}^{+1.08} times more massive when not in the company of an inner super-Earth, while super-Earths are not significantly more massive while in the company of an outer giant planet. We also report an occurrence enhancement for Saturns (median projected mass of 0.6 M J ) while in presence of a super-Earth by a factor of ∼4, and for super-Earths in the presence of Saturns by the same factor. This positive correlation disappears for super-Jupiters (median projected mass of 3.1 M J ). These results show that while cold Jupiters are generally accompanied by inner super-Earths, this does not hold for the largest giant planets, such as those that will be discovered by Gaia, which will likely not be accompanied by transiting planets. The mass dependence, in combination with the different detection limits of different surveys, may explain the discrepancies concerning occurrence relations between cold Jupiters and super-Earths.}, archive = {J_ApJ}, author = {Etienne Lefèvre-Forján and Gijs D. Mulders}, doi = {10.3847/1538-4357/ade715}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {101}, shortjournal = {The Astrophys. J.}, title = {Saturns, but not super-jupiters, occur more frequently in the presence of inner super-earths}, volume = {988}, year = {2025}, }
• (2025). Steady-state heating of diffuse coronal plasma in a solar active region. ApJ, 988(1), 100. (www)

  @article{ , abstract = {The solar corona is much hotter than lower layers of the solar atmosphere—the photosphere and chromosphere. The coronal temperature is up to 1 MK in quiet Sun areas, while up to several megakelvins in active regions, which implies a key role of the magnetic field in coronal heating. This means that understanding coronal heating requires reliable modeling of the underlying 3D magnetic structure of an active region validated by observations. Here, we employ synergy between 3D modeling, optically thick gyroresonant microwave emission, and optically thin EUV emission to (i) obtain and validate the best magnetothermal model of the active region and (ii) disentangle various components of the EUV emission known as diffuse component, bright loops, open-field regions, and “moss” component produced at the transition region. Surprisingly, the best thermal model corresponds to high-frequency energy release episodes, similar to a steady-state heating. Our analysis did not reveal significant deviations of the elemental abundances from the standard coronal values.}, archive = {J_ApJ}, author = {Gregory D. Fleishman and Alexey A. Kuznetsov and Gelu M. Nita}, doi = {10.3847/1538-4357/ade3dd}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {100}, shortjournal = {The Astrophys. J.}, title = {Steady-state heating of diffuse coronal plasma in a solar active region}, volume = {988}, year = {2025}, }
• (2025). Discovery of a giant molecular cloud at the midpoint of the galactic bar dust lanes: M4.7–0.8. ApJ, 988(1), 99. (www)

  @article{ , abstract = {We present the detection of a previously unknown giant molecular cloud (GMC) located at the midpoint of the Galactic Bar Dust Lanes (M4.7–0.8), using spectral line observations taken with the Green Bank Telescope. This  ∼60 pc long GMC is associated with accreting material that is transitioning from the quieter Galactic disk environment to the more extreme central molecular zone (CMZ) environment. Our 24 GHz single-dish radio observations targeted the NH 3 (1,1)−(4,4) and HC 5 N (9−8), known dense gas tracers. The observations reveal the main features of the GMC, which we have dubbed the “Nexus” and “Filament,” covering a 0 \mathop{.}\limits^{\unicode{x000b0}} 5 × 0 \mathop{.}\limits^{\unicode{x000b0}} 25 area at 31 ″ angular resolution. In this publication, we investigate the gas kinematics within the observed region and compare the distribution of molecular emission to previous infrared surveys to better understand the dust component. The observed gas tracers show centrally condensed cores corresponding to the positions of high dust column densities and low dust temperatures. We report the detection of a previously unknown NH 3 (3,3) maser, along with a 70 μ m source association, which supports the identification of this region as being actively star-forming. Gas emission in this region shows broad linewidths, comparable to values seen in CMZ clouds. The overall description of this cloud that we present is that of a highly dynamic region comprising dense gas and dust. This encapsulates a wide range of features associated with star formation, in addition to material transport related to the CMZ.}, archive = {J_ApJ}, author = {Natalie O. Butterfield and Larry K. Morgan and Ashley T. Barnes and Adam Ginsburg and Savannah Gramze and Mark R. Morris and Mattia C. Sormani and Cara D. Battersby and Charlie Burton and Allison H. Costa and Elisabeth A. C. Mills and Jürgen Ott and Michael Rugel and Harrison West}, doi = {10.3847/1538-4357/adc687}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {99}, shortjournal = {The Astrophys. J.}, title = {Discovery of a giant molecular cloud at the midpoint of the galactic bar dust lanes: M4.7–0.8}, volume = {988}, year = {2025}, }
• (2025). Magnetogram-matching Biot–Savart law and decomposition of vector magnetograms. ApJ, 988(1), 98. (www)

  @article{ , abstract = {We generalize a magnetogram-matching Biot–Savart law (BS l ) from planar to spherical geometry. For a given coronal current density J , this law determines the magnetic field \widetilde{{\boldsymbol{B}}} whose radial component vanishes at the surface. The superposition of \widetilde{{\boldsymbol{B}}} with a potential field defined by a given surface radial field, B r , provides the entire configuration where B r remains unchanged by the currents. Using this approach, we (1) upgrade our regularized BS l s for constructing coronal magnetic flux ropes (MFRs) and (2) propose a new method for decomposing a measured photospheric magnetic field as {\boldsymbol{B}}={{\boldsymbol{B}}}_{{\rm{pot}}}+{{\boldsymbol{B}}}_{T}+{{\boldsymbol{B}}}_{\tilde{S}} , where the potential, B pot , toroidal, B T , and poloidal, {{\boldsymbol{B}}}_{\tilde{S}} , fields are determined by B r , J r , and the surface divergence of B – B pot , respectively, all derived from magnetic data. Our B T is identical to the one in the alternative Gaussian decomposition by P. W. Schuck et al., while B pot and {{\boldsymbol{B}}}_{\tilde{S}} are different from their poloidal fields {{\boldsymbol{B}}}_{{\rm{P}}}^{\lt } and {{\boldsymbol{B}}}_{{\rm{P}}}^{\gt } , which are potential in the infinitesimal proximity to the upper and lower side of the surface, respectively. In contrast, our {{\boldsymbol{B}}}_{\tilde{S}} has no such constraints and, as B pot and B T , refers to the same upper side of the surface. In spite of these differences, for a continuous J distribution across the surface, B pot and {{\boldsymbol{B}}}_{\tilde{S}} are linear combinations of {{\boldsymbol{B}}}_{{\rm{P}}}^{\lt } and {{\boldsymbol{B}}}_{{\rm{P}}}^{\gt } . We demonstrate that, similar to the Gaussian method, our decomposition allows one to identify the footprints and projected surface-location of MFRs in the solar corona, as well as the direction and connectivity of their currents.}, archive = {J_ApJ}, author = {Viacheslav S. Titov and Cooper Downs and Tibor Török and Jon A. Linker and Michael Prazak and Jiong A. Qiu}, doi = {10.3847/1538-4357/add895}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {98}, shortjournal = {The Astrophys. J.}, title = {Magnetogram-matching Biot–Savart law and decomposition of vector magnetograms}, volume = {988}, year = {2025}, }
• (2025). JAGB 2.0: Improved constraints on the J-region asymptotic giant branch–based hubble constant from an expanded sample of JWST observations. ApJ, 988(1), 97. (www)

  @article{ , abstract = {The J-region asymptotic giant branch (JAGB) is an overdensity of stars in the near-infrared, attributed to carbon-rich AGB stars, and recently used as a standard candle for measuring extragalactic distances and the Hubble constant. Using JWST in Cycle 2, we extend JAGB measurements to six hosts of nine Type Ia supernovae (SNe Ia; NGC 2525, NGC 3147, NGC 3370, NGC 3447, NGC 5468, and NGC 5861), with two at D ∼ 40 Mpc, all calibrated by the maser host NGC 4258. We investigate the effects of incompleteness and are unable to recover a JAGB measurement for NGC 3147. We compile all JWST JAGB observations of SN Ia hosts, 15 galaxies hosting 18 SNe Ia, from the SH0ES and CCHP programs, and employ all literature measures. We find no significant mean difference between these distances and those from Hubble Space Telescope Cepheids, −0.03 ± 0.02 (stat.) ± 0.05 (sys.) mag. We find a difference of 0.11 ± 0.022 mag between JAGB mode measurements in the CCHP analyses of two fields in NGC 4258, a feature also seen in two SH0ES fields (see field-to-field variations in S. Li et al.), indicating significant variation of NGC 4258 JAGB measurements, which produce a large absolute calibration uncertainty. Variations are also seen in the shape of the JAGB luminosity function (LF) across galaxies so that different measures produce different values of the Hubble constant. We look for but do not (yet) find a standardizing relation between JAGB LF skew or color dependence and the apparent variation. Using the middle result of all JAGB measures to calibrate SNe Ia yields a Hubble constant of H 0 = 73.3 ± 1.4 (stat.) ± 2.0 (sys.) km s −1 Mpc −1 with the systematic dominated by apparent differences across the NGC 4258 calibrating fields or their measures.}, archive = {J_ApJ}, author = {Siyang Li and Adam G. Riess and Daniel Scolnic and Stefano Casertano and Gagandeep S. Anand}, doi = {10.3847/1538-4357/addd0c}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {97}, shortjournal = {The Astrophys. J.}, title = {JAGB 2.0: Improved constraints on the J-region asymptotic giant branch–based hubble constant from an expanded sample of JWST observations}, volume = {988}, year = {2025}, }
• (2025). C-19 and hot, wide star streams. ApJ, 988(1), 96. (www)

  @article{ , abstract = {The C-19 star stream has the abundance characteristics of an unusually metal-poor globular cluster but kinematically is uncharacteristically hot and wide for a cluster stream, having a line-of-sight velocity dispersion of 7  ±  2 km s −1 and a 1 σ width of 240 pc. We show that the tidal dissolution of an old, lower-mass globular cluster in a cold dark matter (CDM) galactic halo can create a hot, wide stream currently near orbital apocenter. A cosmological Milky Way n -body simulation motivates the parameters for an evolving Milky Way halo potential containing an orbiting subhalo population in which we model a star cluster progenitor of C-19. The same model parameters have been used for a GD-1 stream model. The ∼7 km s −1 velocity dispersion is readily accomplished with an evolving CDM subhalo population, a progenitor cluster mass ≃2 × 10 4 M ⊙ , and an orbit that keeps the progenitor orbital pericenter within about 10 kpc of the Milky Way dark halo or its precursors.}, archive = {J_ApJ}, author = {Raymond G. Carlberg and Rodrigo Ibata and Nicolas F. Martin and Else Starkenburg and David S. Aguado and Khyati Malhan and Kim Venn and Zhen Yuan}, doi = {10.3847/1538-4357/ade4ce}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {96}, shortjournal = {The Astrophys. J.}, title = {C-19 and hot, wide star streams}, volume = {988}, year = {2025}, }
• (2025). An ALMA study of molecular complexity in the hot core g336.99-00.03 MM1. ApJ, 988(1), 95. (www)

  @article{ , abstract = {High-mass star formation involves complex processes, with the hot core phase playing a crucial role in chemical enrichment and the formation of complex organic molecules. However, molecular inventories in hot cores remain limited. Using data from the Atacama Large Millimeter/submillimeter Array Three-millimeter Observations of Massive Star-forming regions survey, the molecular composition and evolutionary stages of two distinct millimeter continuum sources in the high-mass star-forming region G336.99-00.03 have been characterized. MM1, with 19 distinct molecular species detected, along with eight isotopologues and several vibrationally/torsionally excited states, has been identified as a hot core. MM2, with only five species identified, was defined as a H ii region. Isotopic ratios in MM1 were derived, with 12 C/ 13 C ranging from 16.0 to 29.2, 16 O/ 18 O at 47.7, and 32 S/ 34 S at 19.2. Molecular abundances in MM1 show strong agreement with other sources and three-phase warm-up chemical models within an order of magnitude for most species. Formation pathways of key molecules were explored, revealing chemical links and reaction networks. This study provides a detailed molecular inventory of two millimeter continuum sources, shedding light on the chemical diversity and evolutionary processes in high-mass star-forming regions. The derived molecular parameters and isotopic ratios offer benchmarks for astrochemical models, paving the way for further investigation into the formation and evolution of complex organic molecules during the hot core phase.}, archive = {J_ApJ}, author = {Chunguo Duan and Qian Gou and Tie Liu and Fengwei Xu and Xuefang Xu and Junlin Lan and Ke Wang and Laurent Pagani and Donghui Quan and Junzhi Wang and Xunchuan Liu and Mingwei He}, doi = {10.3847/1538-4357/addbd6}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {95}, shortjournal = {The Astrophys. J.}, title = {An ALMA study of molecular complexity in the hot core g336.99-00.03 MM1}, volume = {988}, year = {2025}, }
• (2025). Leaky dust traps in planet-embedded protoplanetary disks. ApJ, 988(1), 94. (www)

  @article{ , abstract = {From the survival of dust disks for a few Myr to the establishment of chemical dichotomy, dust traps are expected to play a pivotal role in sculpting protoplanetary disks and the early planet formation process. These traps may not be perfect, as evidenced by both numerical simulations and the observations of disks with gaps and cavities, inside which we detect some amounts of both gas and dust. Using two-fluid hydrodynamic global simulations in both 2D and 3D, we directly compute the dynamics of dust grains as they aerodynamically interact with the disk gas that is being perturbed by an embedded planet. In both 2D and 3D, we find the dust trap to be more leaky for a lower-mass planet and for a more turbulent disk. More crucially, we find that the fraction of dust mass that remains trapped within the pressure bump can be up to an order of magnitude more reduced in 3D compared to 2D, with all else being equal. Our simulations show a complex behavior of dust radial motion that is both azimuthally and poloidally nonuniform, with the overall dynamics dominated by the dust coupling to the gas flow even for Stokes number 0.1. The leaky traps we find suggest that the pebble isolation mass is likely not truly isolating and that gap-opening planets do not establish an unconditional impermeable barrier. Our findings have implications for recent JWST MINDS results, which show that volatiles, including water, are present in the inner regions of disks hosting outer dust rings.}, archive = {J_ApJ}, author = {Pinghui Huang and Fangyuan Yu and Eve J. Lee and Ruobing Dong and Xue-Ning Bai}, doi = {10.3847/1538-4357/addd1f}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {94}, shortjournal = {The Astrophys. J.}, title = {Leaky dust traps in planet-embedded protoplanetary disks}, volume = {988}, year = {2025}, }
• (2025). A possible common physics picture reflected by the gamma-ray emission of the galactic center. ApJ, 988(1), 93. (www)

  @article{ , abstract = {Long-term observations of the Galactic center by Fermi and HESS have revealed a novel phenomenon: the high-energy gamma-ray spectrum from the gamma-ray source HESS J1745-290 exhibits a double power-law structure. In this study, we propose a new explanation for this phenomenon. We suggest that the low-energy (GeV) power-law spectrum originates from interactions between trapped background “sea” cosmic ray particles and the dense gaseous environment near the Galactic center. In contrast, the bubble-like structure in the high-energy (TeV) spectrum is produced by protons accelerated during active phases of the Galactic center, through the same physical process. Based on this framework, we first calculate the gamma-ray emission generated by cosmic ray protons accelerated in the Galactic center. Then, using a spatially dependent cosmic ray propagation model, we compute the energy spectrum of background “sea” cosmic ray protons and their associated diffuse gamma-ray emission in the Galactic center region. The results closely reproduce the observations from Fermi-LAT and HESS, suggesting that their long-term data support this picture: high-energy cosmic rays in the local region originate from nearby cosmic ray sources, while low-energy cosmic rays are a unified contribution from distant cosmic ray sources. We anticipate that this double power-law structure may be widely present in the halo of a Galactic cosmic-ray source or a slow-diffusion region. We hope that future observations will detect more such sources, allowing us to further test and validate our model.}, archive = {J_ApJ}, author = {Lin Nie and Yi-Qing Guo and Si-Ming Liu}, doi = {10.3847/1538-4357/ade3ce}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {93}, shortjournal = {The Astrophys. J.}, title = {A possible common physics picture reflected by the gamma-ray emission of the galactic center}, volume = {988}, year = {2025}, }
• (2025). Multifrequency radio observations of the magnetar swift j1818.0–1607. ApJ, 988(1), 92. (www)

  @article{ , abstract = {We report on Green Bank Telescope observations of the radio magnetar Swift J1818.0–1607 between 820 MHz and 35 GHz, taken from 6 to 9 months after its 2020 March outburst. We obtained multihour observations at six frequencies, recording polarimetric, spectral, and single-pulse information. The spectrum peaks at a frequency of 5.4 ± 0.6 GHz, making Swift J1818.0–1607 one of many radio magnetars that exhibit a gigahertz-peaked spectrum. The radio flux decays steeply above the peak frequency, with in-band spectral indices α < −2.3 above 9 GHz. The emission is highly (>50%) linearly polarized, with a lower degree (<30%) of circular polarization that can change handedness between single pulses. Across the frequency range of our observations, the time-integrated radio profiles share a common shape: a narrow “pulsar-like” central component flanked by “magnetar-like” components comprised of bright, spiky subpulses. The outer profile components exhibit larger degrees of flux modulation when compared to the central pulse component.}, archive = {J_ApJ}, author = {Evan F. Lewis and Harsha Blumer and Ryan S. Lynch and Maura A. McLaughlin}, doi = {10.3847/1538-4357/ade14f}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {92}, shortjournal = {The Astrophys. J.}, title = {Multifrequency radio observations of the magnetar swift j1818.0–1607}, volume = {988}, year = {2025}, }
• (2025). Integrated galaxy light from stacking 105 random pointings in the dark energy survey data. ApJ, 988(1), 91. (www)

  @article{ , abstract = {We present a new technique for measuring the integrated galaxy light (IGL) with stacked image data from the Dark Energy Survey (DES). We extract 1′ × 1′ cutouts from nearly 100,000 randomly selected positions in the g, r, i, z, and Y bands from the DES Data Release 2 maps. We generate source catalogs and masks for each cutout, and the images are subsequently stacked to generate deep images of the sky both with and without sources. The IGL is then calculated by taking the difference in average brightness between stacks that contain galaxies and stacks in which galaxies have been masked. We find IGL values of g = 4.27 ± 0.28, r = 6.97 ± 0.42, i = 8.66 ± 0.53, z = 10.16 ± 0.7, and Y = 13.78 ± 2.35 nW m −2 sr −1 . These measurements, which require no foreground estimation or removal, are in agreement with previously reported IGL values derived from galaxy number counts and other methods. This stacking technique reduces the sensitivity to diffuse local backgrounds but is not sensitive to large-scale diffuse extragalactic background light.}, archive = {J_ApJ}, author = {Jenna E. Moore and Seth H. Cohen and Philip Mauskopf and Evan Scannapieco}, doi = {10.3847/1538-4357/ade309}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {91}, shortjournal = {The Astrophys. J.}, title = {Integrated galaxy light from stacking 105 random pointings in the dark energy survey data}, volume = {988}, year = {2025}, }
• (2025). The impact of applying black Hole–Host galaxy scaling relations to large galaxy populations. ApJ, 988(1), 90. (www)

  @article{ , abstract = {Supermassive black holes (SMBHs) with dynamically measured masses have shown empirical correlations with host galaxy properties. These correlations are often the only method available to estimate SMBH masses and gather statistics for large galaxy populations across a range of redshifts, even though the scaling relations themselves are derived from a small subset of nearby galaxies. Depending on the scaling relation used, estimated SMBH masses can vary significantly. The most widely used scaling relations are the M BH – M bulge and M BH – σ relations, where M bulge is galaxy bulge mass and σ is the bulge velocity dispersion. In this paper, we determine how severely the choice of scaling relation impacts SMBH mass estimates for different subsets of a large galaxy population. For this analysis, we use a sample of ∼400,000 galaxies, including 1240 Type 1 active galactic nuclei from the Sloan Digital Sky Survey. We calculate SMBH masses from M BH – M bulge and M BH – σ and compare to single-epoch virial SMBH masses from broad-line H β , which are derived independently of black hole–host galaxy scaling relations. We find that SMBH masses derived from the single-epoch virial relation for H β are better reproduced by M BH – σ than M BH – M bulge . Finally, in cases where σ and M bulge cannot be measured directly, we show that it is possible to infer σ from photometry with more accuracy than we can infer M bulge .}, archive = {J_ApJ}, author = {Maggie C. Huber and Joseph Simon and Julia M. Comerford}, doi = {10.3847/1538-4357/ade30a}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {90}, shortjournal = {The Astrophys. J.}, title = {The impact of applying black Hole–Host galaxy scaling relations to large galaxy populations}, volume = {988}, year = {2025}, }
• (2025). AMUSE-antlia. II. intracluster X-ray population in the antlia cluster. ApJ, 988(1), 89. (www)

  @article{ , abstract = {We conduct a systematic survey of X-ray sources in the inner ( r ∼ 200 kpc) region of the Antlia cluster based on Chandra observations, down to a source detection limit of L (0.5–8 keV) ∼ 4.2 × 10 −7 ph cm −2 s −1 (2 × 10 38 erg s −1 ). We present an X-ray source catalog with 202 sources and provide their coordinates, multiband flux information, and hardness ratios. We find a statistically significant excess at a significance level of 4.2 σ with 37.6 excess sources beyond 3 times the mean effective radius of the two brightest central galaxies (BCGs). This implies that these excess sources could be a genuine intracluster X-ray population that is not associated with the bulk stellar component. Also, the increased number of excess sources in the fields containing a BCG implies a potential connection between the excess sources and BCGs. The discovery of these sources in the Antlia cluster, together with previous research of similar findings in the other two nearby clusters, Virgo and Fornax, indicates that the intracluster X-ray population could be universal in nearby galaxy clusters. Furthermore, we discuss the candidate origins of the excess sources, including low-mass X-ray binaries (LMXBs) associated with intracluster light (ICL-LMXBs), LMXBs in globular clusters (GC-LMXBs), and supernova-kicked LMXBs (SN-kicked LMXBs). We estimate that the contribution of ICL-LMXBs, which should include the LMXBs related to the stellar halo surrounding BCGs, is unlikely to dominate the intracluster X-ray population in Antlia. Meanwhile, GC-LMXBs and SN-kicked LMXBs, each component could contribute ∼30% to the total excess sources.}, archive = {J_ApJ}, author = {Zhensong Hu and Yuanyuan Su and Zhiyuan Li and Meicun Hou and Ralph P. Kraft and Kelley M. Hess and Hao Chen}, doi = {10.3847/1538-4357/ade3d4}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {89}, shortjournal = {The Astrophys. J.}, title = {AMUSE-antlia. II. intracluster X-ray population in the antlia cluster}, volume = {988}, year = {2025}, }
• (2025). Magnetic fields in the pillars of creation. ApJ, 988(1), 88. (www)

  @article{ , abstract = {Due to dust grain alignment with magnetic fields, dust polarization observations of far-infrared emission from cold molecular clouds are often used to trace magnetic fields, allowing a probe of the effects of magnetic fields on the star formation process. We present inferred magnetic field maps of the Pillars of Creation region within the larger M16 emission nebula, derived from dust polarization data in the 89 and 154 μ m continuum using the Stratospheric Observatory For Infrared Astronomy/High-resolution Airborne Wideband Camera. We derive magnetic field strength estimates using the Davis–Chandrasekhar–Fermi method. We compare the polarization and magnetic field strengths to column densities and dust continuum intensities across the region to build a coherent picture of the relationship between star-forming activity and magnetic fields in the region. The projected magnetic field strengths derived are in the range of ∼50–130 μ G, which is typical for clouds of similar n (H 2 ), i.e., molecular hydrogen volume density on the order of 10 4 –10 5 cm −3 . We conclude that star formation occurs in the finger tips when the magnetic fields are too weak to prevent radial collapse due to gravity but strong enough to oppose OB stellar radiation pressure, while in the base of the fingers the magnetic fields hinder mass accretion and consequently star formation. We also support an initial weak-field model (<50 μ G) with subsequent strengthening through realignment and compression, resulting in a dynamically important magnetic field.}, archive = {J_ApJ}, author = {Adwitiya Sarkar and Leslie W. Looney and Marc W. Pound and Zhi-Yun Li and Ian W. Stephens and Manuel Fernández-López and Simon Coudé and Zhe-Yu Daniel Lin and Haifeng Yang and Reid Faistl}, doi = {10.3847/1538-4357/ade544}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {88}, shortjournal = {The Astrophys. J.}, title = {Magnetic fields in the pillars of creation}, volume = {988}, year = {2025}, }
• (2025). Rapid change in the orbital period of the remnant of nova scorpii AD 1437 (IGR j17014-4306). ApJ, 988(1), 87. (www)

  @article{ , abstract = {IGR J17014-4306 is the longest orbital period (12.8 hr) deep-eclipsing intermediate polar known, where a massive white dwarf (WD) accretes matter from its companion star via an accretion disk. Based on photometric observations from the Transiting Exoplanet Survey Satellite space telescope and the American Association of Variable Star Observers database, 70 eclipse timings were determined. It was also confirmed that the spin pulse profile of the WD does change, which is due to the amplitude variation with opposite trends in spin frequency and its first harmonic. This may be related to fluctuations in the accretion rate. The spin period shows slight fluctuations but no significant changing trends. We constructed the O – C diagram and discovered that the orbital period is increasing at a high rate of {\dot{P}}_{\mathrm{orb}}=+4.3(3)\times 1{0}^{-7}\mathrm{days}\cdot {\mathrm{yr}}^{-1}=+0.037(3){\rm{s}}\cdot {\mathrm{yr}}^{-1} , which is comparable to those detected in compact binary supersoft X-ray sources and recurrent novae. This continuous increase in the orbital period is caused by the mass transfer from the less-massive companion to the WD on its thermal timescale at a high rate. All these findings suggest that IGR J17014-4306 is an interesting target to investigate nova eruption, the real angular momentum loss mechanism, and the overall evolution of cataclysmic variables.}, archive = {J_ApJ}, author = {Lei Zang and Shengbang Qian and Li Zhang and Qibin Sun and Linfeng Chang and Berto Monard and Gordon Myers and Franz-Josef Hambsch}, doi = {10.3847/1538-4357/ade788}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {87}, shortjournal = {The Astrophys. J.}, title = {Rapid change in the orbital period of the remnant of nova scorpii AD 1437 (IGR j17014-4306)}, volume = {988}, year = {2025}, }
• (2025). A galaxy with an extremely blue ultraviolet slope β = −3 at z = 9.25 identified by JWST spectroscopy: Evidence for a weak nebular continuum and efficient ionizing photon escape?. ApJ, 988(1), 86. (www)

  @article{ , abstract = {We investigate UV continuum slopes β of 863 galaxies at 4 < z < 14 using archival JWST/NIRSpec PRISM spectra obtained from major JWST Guaranteed Time Observations (GTO), Early Release Science (ERS), and General Observers (GO) programs, including JADES, CEERS, and UNCOVER. Among these galaxies, we identify a remarkable galaxy at z = 9.25, dubbed extremely blue galaxy 1 (EBG-1), with a significantly blue UV slope β = −2.99 ± 0.15, unlike the rest of the galaxies that exhibit red continua or ambiguous blue continua hindered by large uncertainties. We confirm that the β value negligibly changes by the data reduction and fitting wavelength ranges for UV emission/absorption line masking. The extreme blue slope, β = −3.0, rules out significant contributions from dust extinction or AGN activity. Comparing with stellar and nebular emission models, we find that such a blue UV slope cannot be reproduced solely by stellar models even with very young, metal-poor, or top-heavy contiguous star formation associated with strong nebular continua making the UV slopes red, but with a high ionizing photon escape fraction, {f}_{{\rm{esc}}}^{{\rm{ion}}}\gtrsim 0.5 , for a weak nebular continuum. While the H β emission line is not detected, likely due to the limited sensitivity of the spectrum, we find moderately weak [O iii ] λλ 4959,5007 emission lines for the given star formation rate (3 M ⊙ yr −1 ) and stellar mass (10 8.0 M ⊙ ) that are about 3 times weaker than the average emission lines, again suggestive of the high ionizing photon escape fraction, {f}_{{\rm{esc}}}^{{\rm{ion}}}\sim 0.7 or more. EBG-1 would provide crucial insights into stellar and nebular continuum emission in high-redshift galaxies, serving as an example of the ionizing photon escaping site at the epoch of reionization.}, archive = {J_ApJ}, author = {Hiroto Yanagisawa and Masami Ouchi and Kimihiko Nakajima and Yuichi Harikane and Seiji Fujimoto and Yoshiaki Ono and Hiroya Umeda and Minami Nakane and Hidenobu Yajima and Hajime Fukushima and Yi Xu}, doi = {10.3847/1538-4357/adcecd}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {86}, shortjournal = {The Astrophys. J.}, title = {A galaxy with an extremely blue ultraviolet slope β = −3 at z = 9.25 identified by JWST spectroscopy: Evidence for a weak nebular continuum and efficient ionizing photon escape?}, volume = {988}, year = {2025}, }
• (2025). The crucial role of third body in formation and evolution of contact binary systems: Evidence from CY ari and IK lyn. ApJ, 988(1), 85. (www)

  @article{ , abstract = {CY Ari and IK Lyn are two eclipsing binary systems that share the same spectral type but exhibit significantly different metallicities. Based on the Wilson–Devinney (W-D) method, the first photometric solutions are obtained by analyzing the new complete BVR c I c light curves. The completely eclipsing nature of the light curves allows for the determination of reliable photometric parameters for both systems. Analysis of the light curves indicates that the two systems are structurally similar. Both belong to W-type shallow contact binary systems, with nearly identical degrees of contact. The O − C analysis demonstrates that the orbital periods of CY Ari and IK Lyn are increasing over the long term, with the increase rate for IK Lyn being significantly higher than that for CY Ari. This discrepancy may arise from different mass transfer rates from the secondary star to the primary star. Additionally, a periodic oscillation with a period of 5.4 yr has been detected in CY Ari, potentially attributable to the light-time effect of an unseen third body. An analysis of the age and evolutionary stage elucidates the reasons behind the divergent evolutionary paths of CY Ari and IK Lyn. The presence of the third body accelerates the evolution of CY Ari by removing angular momentum from the central binary pair. Although CY Ari was formed later than IK Lyn, it has evolved into a similar stage. This study provides critical evidence of the significant role played by a third body in the formation and evolution of contact binary systems.}, archive = {J_ApJ}, author = {Hu-Shan Xu and Zhong-Tao Han and Wei-wei Na and Zhi-Hua Wang and Wen-wu Ma and Li-Ying Zhu}, doi = {10.3847/1538-4357/ade152}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {85}, shortjournal = {The Astrophys. J.}, title = {The crucial role of third body in formation and evolution of contact binary systems: Evidence from CY ari and IK lyn}, volume = {988}, year = {2025}, }
• (2025). Extracting the epoch of reionization signal with 3D U-net neural networks using a data-driven systematic effect model. ApJ, 988(1), 84. (www)

  @article{ , abstract = {Neutral hydrogen serves as a crucial probe for the Cosmic Dawn and the Epoch of Reionization (EoR). Actual observations of the 21 cm signal often encounter challenges such as thermal noise and various systematic effects. To overcome these challenges, we simulate SKA-Low-depth images in the South Celestial Pole field and process them with a deep learning method. We utilized foreground residuals acquired by LOFAR during actual North Celestial Pole field observations, thermal and excess variances calculated via Gaussian process regression, and 21 cm signals generated with 21cmFAST for signal extraction tests. Our approach to overcome these foreground, thermal noise, and excess variance components employs a 3D U-Net neural network architecture for image analysis. When considering thermal noise corresponding to 1752 hr of integration time, U-Net provides reliable 2D power spectrum predictions, and robustness tests ensure that we get realistic EoR signals. Adding foreground residuals, however, causes inconsistencies below the horizon delay line. Lastly, evaluating both thermal noise and excess variances with observations up to 4380 hr and 13,140 hr ensures reliable power spectrum estimations within the EoR window and across nearly all scales, respectively. The incoherence of excess variances in the frequency direction can greatly affect deep learning to extract 21 cm signals.}, archive = {J_ApJ}, author = {Li-Yang Gao and Léon V. E. Koopmans and Florent G. Mertens and Satyapan Munshi and Yichao Li and Stefanie A. Brackenhoff and Emilio Ceccotti and J. Kariuki Chege and Anshuman Acharya and Raghunath Ghara and Sambit K. Giri and Ilian T. Iliev and Garrelt Mellema and Xin Zhang}, doi = {10.3847/1538-4357/ade2dc}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {84}, shortjournal = {The Astrophys. J.}, title = {Extracting the epoch of reionization signal with 3D U-net neural networks using a data-driven systematic effect model}, volume = {988}, year = {2025}, }
• (2025). The growth and decay of individual sunspots and pores. ApJ, 988(1), 83. (www)

  @article{ , abstract = {An analysis of the photometric growth and decay rates of sunspots and pores was carried out. According to the Solar Dynamics Observatory/Helioseismic and Magnetic Imager data for the period 2010 May–2025 March, ≈3.5 × 10 5 sunspots and pores were detected and their evolution tracked. The growth and decay rates of sunspots depend nonmonotonically on the area. For small-area sunspots S ≲ 50 μ sh, a rapid increase in velocity is observed with increasing area for the growth stage d{S}_{{\rm{sp}}}^{{\rm{gr}}}\approx 0.2\cdot {S}^{1.35} and for the decay stage d{S}_{{\rm{sp}}}^{{\rm{dc}}}\approx 0.28\cdot {S}^{1.26} μ sh day −1 . For sunspots S ≳ 50 μ sh, the growth rate depends weakly on the area: d{S}_{{\rm{sp}}}^{{\rm{gr}}}\approx 11.9\cdot {S}^{0.32} μ sh day −1 . For the decay stage of sunspots with an area of S ≈ 50–150 μ sh, the decay rate also depends weakly on the area and can be approximated as d{S}_{{\rm{sp}}}^{{\rm{dc}}}\approx 11\cdot {S}^{0.15} . For sunspot areas S ≳ 150 μ sh, the decay rate accelerates with increasing area: d{S}_{{\rm{sp}}}^{{\rm{dc}}}\approx 0.14\cdot {S}^{0.96} μ sh day −1 . For solar pores, the growth and decay rates of solar pores are linearly related to the area. The growth and decay rates for the spots of the leading and trailing polarities are determined. In the range of spot areas S ≈ 100–200 μ sh, the growth and decay rates of sunspots of trailing polarity are higher than those of sunspots of leading polarity.}, archive = {J_ApJ}, author = {Andrei G. Tlatov}, doi = {10.3847/1538-4357/ade790}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {83}, shortjournal = {The Astrophys. J.}, title = {The growth and decay of individual sunspots and pores}, volume = {988}, year = {2025}, }
• (2025). Prestellar cores in turbulent clouds: Properties of critical cores. ApJ, 988(1), 82. (www)

  @article{ , abstract = {A fraction of the dense cores within a turbulent molecular cloud will eventually collapse to form stars. Identifying the physical criteria for instability and analyzing critical core properties is therefore necessary to star formation theory. Here we quantify the characteristics of an ensemble of “critical cores” on the verge of collapse. This critical epoch was identified in a companion paper, which followed the dynamical evolution of prestellar cores in numerical simulations of turbulent, self-gravitating clouds. We find that radial profiles of density and turbulent velocity dispersion in individual critical cores are consistent with our new model for turbulent equilibrium spheres. While a global linewidth–size relation exists for a cloud with given size and Mach number, the turbulent scaling relations around each core exhibit significant variations. As a result, there is no single density threshold for collapse; instead, cores collapse at a range of densities determined by the local sonic scale and gravitational potential environment. The critical cores in our simulations are mostly transonic; we do not find either purely thermal or highly turbulent cores. In our low Mach number model, which better resolves the characteristic mass and sonic scales, we find marginal evidence that the core mass function (CMF) of critical cores peaks around a characteristic mass scale associated with the large-scale cloud properties. We highlight the importance of constructing the CMF at the critical time for the purpose of testing gravoturbulent fragmentation theories, and derive the resolution requirements to unambiguously identify the peak of the CMF.}, archive = {J_ApJ}, author = {Sanghyuk Moon and Eve C. Ostriker}, doi = {10.3847/1538-4357/ade239}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {82}, shortjournal = {The Astrophys. J.}, title = {Prestellar cores in turbulent clouds: Properties of critical cores}, volume = {988}, year = {2025}, }
• (2025). Penetrative convection in rotating tilted f-plane with multiple radiative and convective layers. ApJ, 988(1), 81. (www)

  @article{ , abstract = {In this paper, we conducted a linear instability analysis to investigate penetrative convection in rotating, tilted f -planes with multiple convectively stable and unstable layers. Our findings indicate that penetrative distance decreases with increasing rotational and stratification strengths. We also observed that teleconvection, multiroll convection, and cutoff convection, previously identified in two-layer models, are present in multilayer models. For a three-layer model, the flow exhibits an up-down symmetric pattern for penetrative convection at the poles. However, this symmetry is disrupted in tilted f -planes when the flow drifts in equatorward or poleward directions. At mid- to low latitudes, poleward flow tends to enhance penetration in the upper layers, while equatorward flow facilitates penetration in the lower layers. The disruption of up-down symmetry is also observed in multilayer models with more layers when oscillatory convection occurs. Our findings suggest that upward and downward penetration could be significantly different in stars or planets with multilayer structures. However, under a strong stable composition gradient, the instability is found to be reduced.}, archive = {J_ApJ}, author = {Sethulakshmy Edathara Sreenivasan and Tao Cai}, doi = {10.3847/1538-4357/ade2d6}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {81}, shortjournal = {The Astrophys. J.}, title = {Penetrative convection in rotating tilted f-plane with multiple radiative and convective layers}, volume = {988}, year = {2025}, }
• (2025). Fundamental parameters for totally eclipsing contact binaries observed by TESS. ApJ, 988(1), 80. (www)

  @article{ , abstract = {Totally eclipsing contact binaries provide a unique opportunity to accurately determine mass ratios through photometric methods alone, eliminating the need for spectroscopic data. Studying low mass ratio (LMR) contact binaries is crucial for advancing our understanding of binary star evolution and the formation of rare optical transients known as red novae. We identified 143 totally eclipsing contact binaries from the Transiting Exoplanet Survey Satellite. These high-precision light curves reveal a distinct O’Connell effect, which we interpret by introducing a cool spot on the primary star. Training a neural network model that includes cool spot parameters can generate a high-precision light curve 2 orders of magnitude faster than Phoebe. Utilizing the neural network (NN nol 3 ) model combined with the Markov Chain Monte Carlo algorithm, we rapidly derived the fundamental parameters of these systems. By leveraging the relationship between orbital period and semimajor axis using the Random Sample Consensus algorithm, we estimated their absolute parameters. Our analysis identified 96 targets with mass ratios below 0.25, all of which were not listed in any previous catalog, thus signifying the discovery of new LMR system candidates. Assuming all 143 binary systems are affected by a third light during parameter estimation, we train a neural network (NN l 3 ) model considering the third light. Then we calculate the residuals between the mass ratio q l 3 (considering the third light) and q nol 3 (neglecting it). For these residuals, the 25th percentile ( Q 1 ) is 0.012, the median ( Q 2 ) is 0.026, and the 75th percentile ( Q 3 ) is 0.05.}, archive = {J_ApJ}, author = {Xu Ding and KaiFan Ji and ZhiMing Song and XueFen Tian and JinLiang Wang and ChuanJun Wang and QiYuan Cheng and JianPing Xiong}, doi = {10.3847/1538-4357/addfcf}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {80}, shortjournal = {The Astrophys. J.}, title = {Fundamental parameters for totally eclipsing contact binaries observed by TESS}, volume = {988}, year = {2025}, }
• (2025). Response of the LMC’s bar to a recent SMC collision and implications for the SMC’s dark matter profile. ApJ, 988(1), 79. (www)

  @article{ , abstract = {The LMC’s stellar bar is offset from the outer disk center, tilted from the disk plane, and does not drive gas inflows. These properties are atypical of bars in gas-rich galaxies, yet the LMC bar’s strength and radius are similar to typical barred galaxies. Using N -body hydrodynamic simulations, we show that the LMC’s unusual bar is explainable if there was a recent collision (impact parameter ≈2 kpc) between the LMC and SMC. Pre-collision, the simulated bar is centered and coplanar. Post-collision, the simulated bar is offset (≈1.5 kpc) and tilted (≈8 \mathop{.}\limits^{\unicode{x000b0}} 6). The simulated bar offset reduces with time, and comparing with the observed offset (≈0.8 kpc) suggests the timing of the true collision to be 150–200 Myr ago. Then, 150 Myr post-collision, the LMC’s bar is centered with its dark matter (DM) halo, whereas the outer disk center is separated from the DM center by ≈1 kpc. The SMC collision produces a tilted-ring structure for the simulated LMC, consistent with observations. Post-collision, the simulated LMC bar’s pattern speed decreases by a factor of 2. We also provide a generalizable framework to quantitatively compare the LMC’s central gas distribution in different LMC–SMC interaction scenarios. We demonstrate that the SMC’s torques on the LMC’s bar during the collision are sufficient to explain the observed bar tilt, provided the SMC’s total mass within 2 kpc was (0.8–2.4) × 10 9 M ⊙ . Therefore, the LMC bar’s tilt constrains the SMC’s pre-collision DM profile, and requires the SMC to be a DM-dominated galaxy.}, archive = {J_ApJ}, author = {Himansh Rathore and Gurtina Besla and Kathryne J. Daniel and Leandro Beraldo e Silva}, doi = {10.3847/1538-4357/ade0ae}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {79}, shortjournal = {The Astrophys. J.}, title = {Response of the LMC’s bar to a recent SMC collision and implications for the SMC’s dark matter profile}, volume = {988}, year = {2025}, }
• (2025). Monte carlo evaluations of gamma-ray and radio pulsar populations. ApJ, 988(1), 78. (www)

  @article{ , abstract = {Based on well-grounded Galactic neutron star populations formed from radio pulsar population syntheses of canonical pulsars (CPs) and millisecond pulsars (MSPs), we use the latest Fermi Large Area Telescope catalog (4FGL-DR4) to investigate the implications of proposed γ -ray luminosity models. Using Monte Carlo techniques, we calculate the number of CPs and MSPs that would comprise the sample of pulsar-like unidentified sources (PLUIDs) in 4FGL-DR4. While radio beaming fractions were used to scale the sizes of the populations, when forming the mock 4FGL-DR4 samples we make the simplifying assumption that all γ -ray pulsars are beaming toward the Earth. We then explore the observable outcomes of seven different γ -ray luminosity models. Four of the models provide a good match to the observed number of PLUIDs, while three others significantly overpredict the number of PLUIDs. For these latter models, either the average beaming fraction of γ -ray pulsars is more like 25%–50%, or a revision in the luminosity scaling is required. Most of the radio-detectable MSPs that our models predict as part of the PLUIDs within 4FGL-DR4 are, unsurprisingly, fainter than the currently observed sample and at larger dispersion measures. For CPs, in spite of an excellent match to the observed radio population, none of the γ -ray models we investigated could replicate the observed sample of 150 γ -ray CPs. Further work is required to understand this discrepancy. For both MSPs and CPs, we provide encouraging forecasts for targeted radio searches of PLUIDs from 4FGL-DR4 to elucidate the issues raised in this study.}, archive = {J_ApJ}, author = {Shawaiz Tabassum and Duncan R. Lorimer}, doi = {10.3847/1538-4357/ade13f}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {78}, shortjournal = {The Astrophys. J.}, title = {Monte carlo evaluations of gamma-ray and radio pulsar populations}, volume = {988}, year = {2025}, }
• (2025). FUOr-aur 0544+3330: A new young stellar object outburst in the outskirts of auriga OB1, viewed face-on. ApJ, 988(1), 77. (www)

  @article{ , abstract = {We present a newly appreciated FU Ori outburst event that began in 2019 and reached a peak in early 2021. Suspected young stellar object WISE J054452.25+333009.6 experienced substantial brightening, in excess of −5 mag at optical wavelengths and −2.5 mag at mid-infrared wavelengths. The time from near-quiescence to peak brightness was approximately 24 months. Optical and near-infrared spectra confirm that the outbursting source (hereby designated FUOr-Aur 0544+3330) shows all the hallmarks of the FU Ori class, including the Li i indicator of stellar youth. The mix of ionized and neutral atomic lines, alongside prominent molecular absorption features, is consistent with the expected change in spectral type from earlier in the optical to later types in the near-infrared. The closest analog among well-studied FU Ori objects is V1515 Cyg. Both sources have unusually narrow-lined absorption spectra that can be explained by a face-on disk orientation, such that disk-broadening is minimized and wind-induced blueshift (in e.g., H α , NaD, Ca ii ) is maximized. Both the optical through infrared spectral energy distribution and high-resolution spectrum are well-fit by a pure-accretion disk model. Adopting a distance of d = 1.5 kpc, the accretion and central star parameters are \dot{M}=1{0}^{-5.48} M ⊙ yr −1 , M * = 0.17 M ⊙ , and R inner = 1.04 R ⊙ . Other fitted values are disk inclination i = 5.9 deg and source extinction A V = 1.83 mag. These parameters yield accretion luminosity L acc = 8.4 L ⊙ and maximum disk temperature {T}_{{\rm{\max }}}=6218 K.}, archive = {J_ApJ}, author = {Lynne A. Hillenbrand and Adolfo S. Carvalho and Dan Stern and Michael Connelley and Facundo Pérez Paolino and Ahaan Shetty and Zachariah Milby and Howard Isaacson}, doi = {10.3847/1538-4357/ade14d}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {77}, shortjournal = {The Astrophys. J.}, title = {FUOr-aur 0544+3330: A new young stellar object outburst in the outskirts of auriga OB1, viewed face-on}, volume = {988}, year = {2025}, }
• (2025). Statistical study on the solar wind turbulence spectra upstream of mars. ApJ, 988(1), 76. (www)

  @article{ , abstract = {We statistically analyze the power spectral density (PSD) of magnetic field turbulence in the upstream solar wind of the Martian bow shock by investigating the data from Tianwen-1 and Mars Atmosphere and Volatile Evolution (MAVEN) during 2021 November 13 and December 31. The spectral indices and break frequencies of these PSDs are automatically identified. According to the profiles of the PSDs, we find that they could be classified into three types: A, B, and C. Only less than a quarter of the events exhibit characteristics similar to the 1 au PSDs (Type A). We observe the energy injection in more than one-third of the events (Type B), and the injected energy usually results in the steeper spectral indices of the dissipation ranges. We find the absence of the dissipation range in over one third of the PSDs (Type C), which is likely due to the dissipation occurring at higher frequencies rather than proton cyclotron resonant frequencies. We also find that the two spacecraft observed different types of PSDs in more than half of the investigated episodes, indicating significant variability upstream of the Martian bow shock. For example, the Type-B PSDs are more often seen by Tianwen-1, which was near the flank of the bow shock, than by MAVEN near the nose. This statistical study demonstrates the complicated turbulent environment of the solar wind upstream of the Martian bow shock.}, archive = {J_ApJ}, author = {Zhuxuan Zou and Yuming Wang and Zhenpeng Su and Long Cheng and Zhiyong Wu and Tielong Zhang and Guoqiang Wang and Sudong Xiao and Yutian Chi and Zonghao Pan and Xinjun Hao and Yiren Li and Kai Liu}, doi = {10.3847/1538-4357/ade30c}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {76}, shortjournal = {The Astrophys. J.}, title = {Statistical study on the solar wind turbulence spectra upstream of mars}, volume = {988}, year = {2025}, }
• (2025). A catalog of galactic supernova remnants and supernova remnant candidates from the EMU/POSSUM radio sky surveys. i.. ApJ, 988(1), 75. (www)

  @article{ , abstract = {We use data from the Evolutionary Map of the Universe (EMU) and Polarization Sky Survey of the Universe’s Magnetism (POSSUM) radio southern sky surveys, conducted with the Australian Square Kilometre Array Pathfinder (ASKAP) to compile a catalog of Galactic supernova remnants (SNRs) and candidate SNRs within the region of 277 \mathop{.}\limits^{\unicode{x000b0}} 5 ≤ ℓ ≤ 311 \mathop{.}\limits^{\unicode{x000b0}} 7 Galactic longitude, ∣ b ∣ ≤ 5 \mathop{.}\limits^{\unicode{x000b0}} 4 Galactic latitude, as well as an additional field along the Galactic plane, approximately 315 \mathop{.}\limits^{\unicode{x000b0}} 5 ≤ ℓ ≤ 323 \mathop{.}\limits^{\unicode{x000b0}} 0 Galactic longitude, −4.5 ≤ b ≤ 1.5 Galactic latitude. In the areas studied, there are 44 known SNRs and 46 SNR candidates that have been previously identified in the radio. We confirm eight of these candidates as SNRs based on evidence of linear polarization or through the calculation of nonthermal spectral indices. Additionally, we identify possible radio counterparts for seven SNR candidates that were previously only identified in X-rays (four) or optical (three). We also present six new SNRs and 37 new SNR candidates. The results of this study demonstrate the utility of ASKAP for discovering new and potential SNRs and refining the classification of previously identified candidates. In particular, we find that the EMU and POSSUM surveys are particularly well suited for observing high-latitude SNRs and confirming SNR candidates with polarization. The region studied in this work represents approximately one-quarter of the Galactic plane, by longitude, that will eventually be surveyed by EMU/POSSUM, and we expect that the ongoing surveys will continue to uncover new SNRs and SNR candidates.}, archive = {J_ApJ}, author = {B. D. Ball and R. Kothes and E. Rosolowsky and C. Burger-Scheidlin and M. D. Filipović and S. Lazarević and Z. J. Smeaton and W. Becker and E. Carretti and B. M. Gaensler and A. M. Hopkins and D. Leahy and M. Tahani and J. L. West and C. S. Anderson and S. Loru and Y. K. Ma and N. M. McClure-Griffiths and M. J. Michałowski}, doi = {10.3847/1538-4357/addc63}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {75}, shortjournal = {The Astrophys. J.}, title = {A catalog of galactic supernova remnants and supernova remnant candidates from the EMU/POSSUM radio sky surveys. i.}, volume = {988}, year = {2025}, }
• (2025). Strong photospheric heating indicated by fe i 6173 Å line emission during white-light solar flares. ApJ, 988(1), 74. (www)

  @article{ , abstract = {Between 2017 and 2024, the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory has observed numerous white-light solar flares (WLFs). HMI spectropolarimetric observations of certain WLFs, in particular the X9.3 flare of 2017 September 6, reveal one or more locations within the umbra or along the umbra/penumbra boundary of the flaring active region where the Fe I 6173 Å line briefly goes into full emission, indicating significant heating of the photosphere and lower chromosphere. For five flares featuring Fe I 6173 Å line-core emission, we perform spectropolarimetric analysis using HMI 90 s cadence Stokes data. For all investigated flares, line-core emission is observed to last for a single 90 s frame and is either concurrent with or followed by an increase in the line continuum intensity lasting one to two frames (90–180 s). Additionally, permanent changes to the Stokes Q , U , and/or V profiles were observed, indicating long-lasting nontransient changes to the photospheric magnetic field. These emissions coincided with local maxima in hard X-ray emission observed by Konus-Wind, as well as local maxima in the time derivative of soft X-ray emission observed by GOES 16-18. Comparison of the Fe I 6173 Å line profile synthesis for the ad hoc heating of the initial empirical VAL-S umbra model and quiescent-Sun (VAL-C-like) model indicates that the Fe I 6173 Å line emission in the white-light flare kernels could be explained by the strong heating of initially cool photospheric regions.}, archive = {J_ApJ}, author = {Samuel Granovsky and Alexander G. Kosovichev and Viacheslav M. Sadykov and Graham S. Kerr and Joel C. Allred}, doi = {10.3847/1538-4357/addd1e}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {74}, shortjournal = {The Astrophys. J.}, title = {Strong photospheric heating indicated by fe i 6173 Å line emission during white-light solar flares}, volume = {988}, year = {2025}, }
• (2025). Efficient ionizers with low hβ + [O iii] equivalent widths: JADES spectroscopy of a peculiar high-redshift population. ApJ, 988(1), 73. (www)

  @article{ , abstract = {Early JWST photometric studies discovered a population of UV-faint ( \lt {{L}}_{{\rm{UV}}}^{* } ) z ∼ 6.5–8 Lyman break galaxies with spectral energy distributions implying young ages (∼10 Myr) yet relatively weak H β + [O iii ] equivalent widths (EW H β + [O iii ] ≈ 400 Å). These galaxies seemingly contradict the implicit understanding that young star-forming galaxies are ubiquitously strong H β + [O iii ] emitters, i.e., extreme emission line galaxies (EW ≳750 Å). Low metallicities, high Lyman continuum escape fractions, and rapidly declining star formation histories have been proposed as primary drivers behind low H β + [O iii ] EWs, but the blend of H β + [O iii ] in photometric studies makes proving one of these scenarios difficult. We aim to characterize this peculiar population with deep spectroscopy from the JWST Advanced Deep Extragalactic Survey. We find that a significant subset of these galaxies at z ≳ 2 with modest H β + [O iii ] EWs (≈300–600 Å) have high ionization efficiencies ( {\mathrm{log}}\,{\xi }_{\mathrm{ion}}\gtrsim 25.5\,\mathrm{Hz}\,{\mathrm{erg}}^{-1} ). Suppressed [O iii ] EW values yet elevated H α and H β EW values imply that the level of chemical enrichment is the primary culprit, supported by spectroscopic measurements of metallicities below 12 + log(O/H) ≈ 7.70 (0.1 Z ⊙ ). We demonstrate that integrated H β + [O iii ] selections (e.g., H β + [O iii ] EW > 700 Å) exclude the most metal-poor efficient ionizers and favor (1) more chemically enriched systems with comparable extreme radiation fields and (2) older starbursting systems. In contrast, metallicity degeneracies are reduced in H α space, enabling the identification of these metal-poor efficient ionizers by their specific star formation rate.}, archive = {J_ApJ}, author = {Isaac H. Laseter and Michael V. Maseda and Charlotte Simmonds and Ryan Endsley and Daniel Stark and Andrew J. Bunker and Rachana Bhatawdekar and Kristan Boyett and Alex J. Cameron and Stefano Carniani and Mirko Curti and Zhiyuan Ji and Pierluigi Rinaldi and Aayush Saxena and Sandro Tacchella and Chris Willott and Joris Witstok and Yongda Zhu}, doi = {10.3847/1538-4357/adddb5}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {73}, shortjournal = {The Astrophys. J.}, title = {Efficient ionizers with low hβ + [O iii] equivalent widths: JADES spectroscopy of a peculiar high-redshift population}, volume = {988}, year = {2025}, }
• (2025). ALMA-JELLY. i. high resolution CO(2–1) observations of ongoing ram pressure stripping in NGC 4858 reveal asymmetrical gas tail formation and fallback. ApJ, 988(1), 72. (www)

  @article{ , abstract = {We present new CO(2–1) observations (resolution ∼1″ = 460 pc) of the Coma cluster jellyfish galaxy NGC 4858 obtained from the ALMA-JELLY large program. Analyzing this data alongside complimentary Subaru H α and Hubble Space Telescope (F600LP / F350LP) observations, we find numerous structural and kinematic features indicative of the effects from strong, inclined ram pressure, including an asymmetric inner gas tail. We estimate a highly inclined disk-wind angle of {\phi }_{\,\rm{DW}\,}=7{5}_{-27}^{+10} . By subtracting a simple circular velocity model, we find (1): gas clumps that are being accelerated by ram pressure, and (2): signatures of gas clumps that had been previously pushed out of the disk but are now falling inward. We also discuss head-tail morphologies in star complexes within the stellar disk that appear to be ram pressure stripping (RPS)-influenced. Lastly, we compare this galaxy to state-of-the-art galaxy “wind tunnel” simulations. We find that this galaxy is one of the best nearby examples of strong and inclined ram pressure gas stripping, and of gas that is perturbed by ram pressure but not fully stripped and falls back. We emphasize the importance of torques due to ram pressure in highly inclined interactions, which help drive gas inward on the side rotating against the wind, contributing to the formation of asymmetric inner RPS tails.}, archive = {J_ApJ}, author = {Harrison J. Souchereau and Jeffrey D. P. Kenney and Pavel Jáchym and Ming Sun and William J. Cramer and Masafumi Yagi and Alessandro Boselli and Elias Brinks and Francoise Combes and Luca Cortese and Boris Deshev and Matteo Fossati and Romana Grossová and Rongxin Luo and Jan Palouš and Tom C. Scott}, doi = {10.3847/1538-4357/adde47}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {72}, shortjournal = {The Astrophys. J.}, title = {ALMA-JELLY. i. high resolution CO(2–1) observations of ongoing ram pressure stripping in NGC 4858 reveal asymmetrical gas tail formation and fallback}, volume = {988}, year = {2025}, }
• (2025). Where is the supervirial gas? the supply from hot inflows. ApJ, 988(1), 71. (www)

  @article{ , abstract = {To understand the presence of the supervirial temperature gas detected in the Milky Way (MW), we present our findings from isolated galaxy simulations of MW-mass systems using GIZMO with the Feedback in Realistic Environments (FIRE-2) stellar feedback model. It unveils the presence of a significant supervirial temperature ( T > T vir ) gas component within 20 kpc from the galactic center. We also find that 70%–90% of the total supervirial gas is extraplanar, at 1 < z < 6 kpc and R cyl < 15 kpc. This supervirial gas has a mass of 1−2 × 10 7 M ⊙ with typical gas densities are 10 −3.5 −10 −2.5 cm −3 . We find that some of the virial gas ( T ∼ 10 6 K) forms a rotating hot inflow, where gravitational energy is converted to thermal energy mainly via compressive heating. This process causes gas falling close to the rotation axis to reach supervirial temperatures via a combination of compressive heating and shocks just before cooling and joining the disk. Stellar feedback heating accounts for less than 1% of the supervirial gas, indicating its minimal influence despite expectations. Even in scenarios with no stellar feedback effects considered, abundant supervirial gas persists, highlighting the dominance of alternative heating mechanisms. We also show that cosmic rays do not have a significant effect on heating the gas to a supervirial temperature. Our study illuminates the intricate dynamics of hot virial and supervirial gas surrounding MW-mass galaxies, emphasizing the prominent role of infall-driven compressive and shock-heating processes in shaping thermal evolution.}, archive = {J_ApJ}, author = {Manami Roy and Kung-Yi Su and Smita Mathur and Jonathan Stern}, doi = {10.3847/1538-4357/ade059}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {71}, shortjournal = {The Astrophys. J.}, title = {Where is the supervirial gas? the supply from hot inflows}, volume = {988}, year = {2025}, }
• (2025). Major mergers mean major offset: Drivers of intrinsic scatter in the MGCS–Mh scaling relation for massive elliptical galaxies. ApJ, 988(1), 70. (www)

  @article{ , abstract = {In this work, we determine the total globular cluster (GC) counts and globular cluster system (GCS) total mass estimates for 27 extremely massive elliptical galaxies. The GC 2D spatial distributions of these galaxies were created from photometry of Hubble Space Telescope images using DOLPHOT in the near-IR wavelength range. The projected radial density profiles of these GCSs were determined using a Voronoi-tessellation-based technique introduced in our previous paper. We then plot these galaxies on the GCS–halo mass relation alongside previously studied galaxies in the literature. The relation now extends across seven decades of halo mass. We find that the 1:1 slope of this relation holds out to the highest-mass galaxies, although extremely massive BCG galaxies are shifted to higher GCS masses than their lower-mass galaxy counterparts. We find a negative correlation with massive galaxies’ offset from the GCS–halo mass relation and the steepness of their GCS density profiles, and that this is being driven by the red GC populations. We suggest that the biggest influence in intrinsic scatter in the GCS–halo mass relation for massive galaxies is through a few major mergers resulting in accretion of massive satellites with old, red GC populations, rather than many accretions of small satellites with younger, blue GC populations.}, archive = {J_ApJ}, author = {Veronika Dornan and William E. Harris}, doi = {10.3847/1538-4357/ade05e}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {70}, shortjournal = {The Astrophys. J.}, title = {Major mergers mean major offset: Drivers of intrinsic scatter in the MGCS–Mh scaling relation for massive elliptical galaxies}, volume = {988}, year = {2025}, }
• (2025). Microphysics of circumgalactic turbulence probed by fast radio bursts and quasars. ApJ, 988(1), 69. (www)

  @article{ , abstract = {The circumgalactic medium (CGM) is poorly constrained at the subparsec scales relevant to turbulent energy dissipation and regulation of multiphase structure. Fast radio bursts are sensitive to small-scale plasma density fluctuations, which can induce multipath propagation (scattering). The amount of scattering depends on the density fluctuation spectrum, including its amplitude {C}_{{\rm{n}}}^{2} , spectral index β , and dissipation scale l i . We use quasar observations of CGM turbulence at ≳pc scales to infer {C}_{{\rm{n}}}^{2} , finding it to be 1{0}^{-16}\lesssim {C}_{{\rm{n}}}^{2}\lesssim 1{0}^{-9} m −20/3 for hot ( T > 10 6 K) gas and 1{0}^{-8}\lesssim {C}_{{\rm{n}}}^{2}\lesssim 1{0}^{-4} m −20/3 for cool (10 4 ≲ T ≲ 10 5 K) gas, depending on the gas sound speed and density. These values of {C}_{{\rm{n}}}^{2} are much smaller than those inferred in the interstellar medium at similar physical scales. The resulting scattering delays from the hot CGM are negligible (≪1 μ s at 1 GHz), but they are more detectable from the cool gas as either radio pulse broadening or scintillation, depending on the observing frequency and sightline geometry. Joint quasar-FRB observations of individual galaxies can yield lower limits on l i , even if the CGM is not a significant scattering site. An initial comparison between quasar and FRB observations (albeit for different systems) suggests l i ≳ 750 km in ∼10 4 K gas in order for the quasar and FRB constraints to be consistent. If a foreground CGM is completely ruled out as a source of scattering along an FRB sightline, then l i may be comparable to the smallest cloud sizes (≲pc) inferred from photoionization modeling of quasar absorption lines.}, archive = {J_ApJ}, author = {Stella Koch Ocker and Mandy C. Chen and S. Peng Oh and Prateek Sharma}, doi = {10.3847/1538-4357/ade0bc}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {69}, shortjournal = {The Astrophys. J.}, title = {Microphysics of circumgalactic turbulence probed by fast radio bursts and quasars}, volume = {988}, year = {2025}, }
• (2025). Wind-fed supermassive black hole accretion by the nuclear star cluster: The case of m31*. ApJ, 988(1), 68. (www)

  @article{ , abstract = {The central supermassive black hole (SMBH) of the Andromeda galaxy, known as M31*, exhibits dim electromagnetic emission and is inferred to have an extremely low accretion rate for its remarkable mass (∼10 8 M ⊙ ). In this work, we use three-dimensional hydrodynamical simulations to explore a previously untested scenario, in which M31* is fed by the collective stellar mass loss from its surrounding nuclear star cluster, manifested as a famous eccentric disk of predominantly old stellar populations. The stellar mass loss is assumed to be dominated by the slow and cold winds from 100 asymptotic giant-branch stars, which follow well-constrained Keplerian orbits around M31* and together provide a mass injection rate of ∼4 × 10 −5 M ⊙ yr −1 . The simulations achieve a quasi-steady state on a megayear timescale, at which point a quasi-Keplerian, cool ( T ∼ 10 3 –10 4 K) gas disk extending several parsecs is established. This disk is continuously supplied by the stellar winds and itself feeds the central SMBH. At the end of the simulations at 2 Myr, an accretion rate of ∼2 × 10 −5 M ⊙ yr −1 is found but could vary by a factor of a few depending on whether the subdominant gravity of the NSC or a moderate global inflow is included. The predicted X-ray luminosity of ∼10 36 erg s −1 , dominated by the hot ( T ∼ 10 7 –10 8 K) plasma within 0.2 pc of the SMBH, is consistent with Chandra observations. We conclude that the feeding mechanism of M31* is successfully identified, which has important implications for the working of dormant SMBHs prevalent in the local Universe.}, archive = {J_ApJ}, author = {Zhao Su and Zhiyuan Li and Zongnan Li}, doi = {10.3847/1538-4357/ade1d5}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {68}, shortjournal = {The Astrophys. J.}, title = {Wind-fed supermassive black hole accretion by the nuclear star cluster: The case of m31*}, volume = {988}, year = {2025}, }
• (2025). Electron acceleration at shock ripples: Role of pitch-angle diffusion. ApJ, 988(1), 67. (www)

  @article{ , abstract = {Suprathermal electrons are routinely observed in interplanetary space. At higher energies, there are in-situ evidences that shocks, both interplanetary shocks, often driven by fast coronal mass ejections, and terrestrial bow shocks, can accelerate electrons up to transrelativistic energies (∼MeVs). The acceleration mechanism responsible for these energetic electrons is still under debate. In this work, we study the effects of large-scale shock ripples on electron acceleration at a quasi-perpendicular shock in a 2D system. For tractability of the numerical simulation, we consider the scenario where the magnetic field line contains ripples, and the shock is assumed planar and piecewise. The propagation of gyrophase-averaged electrons is governed by the focused transport equation, where the effect of the turbulent magnetic field is modeled by the pitch-angle diffusion, described by the quasi-linear theory. A Monte Carlo simulation on the equivalent time-forward Itô stochastic differential equation is performed within a periodic box to obtain the phase-space distribution function of the accelerated electrons. Our model predicts power-law energy spectra with a cutoff at high-energy ends, whereas their spectral indices are softer than those predicted by the diffusive shock acceleration theory. We demonstrate that, with a suitable choice of pitch-angle diffusion strength, a small fraction of electrons can experience magnetic traps in multiple ripples along the shock surface, boosting their energies to ∼MeVs. Our results therefore provide a framework for a better understanding of relativistic electron events associated with shocks within the heliosphere.}, archive = {J_ApJ}, author = {Y. D. Xu and G. Li and S. Yao}, doi = {10.3847/1538-4357/ade23e}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {67}, shortjournal = {The Astrophys. J.}, title = {Electron acceleration at shock ripples: Role of pitch-angle diffusion}, volume = {988}, year = {2025}, }
• (2025). Orbital decay of the ultra-hot jupiter TOI-2109b: Tidal constraints and transit-timing analysis. ApJ, 988(1), 66. (www)

  @article{ , abstract = {TOI-2109b is the ultra-hot Jupiter with the shortest orbital period (∼16 hr) yet discovered. At this close distance, strong tidal interactions can produce a significant exchange of angular momentum with the star. Since the orbital period of this planet is shorter than the stellar rotation period, TOI-2109b may be an optimal candidate for studying orbital decay. This process depends on how efficiently the star and the planet dissipate energy, due mainly to interior mechanisms that are poorly constrained in exoplanet systems. In this work, we study for the first time the tidal evolution of TOI-2109b under a formalism of inertial waves (IWs) in convective envelopes and internal gravity waves (IGWs) in stellar radiative regions. We find that uncertainties in the age of TOI-2109 ( t ⋆,age ) significantly affect the rate of orbital evolution, as IWs and IGWs interact differently depending on t ⋆,age . For an “old” host star, we find that TOI-2109b would undergo fast orbital decay. Conversely, if TOI-2109b orbits a “young” host star, a rather slow decay rate for {Q}_{\star }^{{\prime} }\gt 2.3\times 1{0}^{7} would suggest a constant-period orbit. Our calculated mid-transit times and transit-timing variations (TTVs) support a “young” host star with {Q}_{\star }^{{\prime} }\gt 3.7\times 1{0}^{7} , suggesting a decay rate \dot{P}\sim 4\,{\rm{ms}}\,{{\rm{yr}}}^{-1} that could lead to mid-transit-time shifts ≲10 s over three years. Orbital decay and other TTV-inducing effects will be confirmed or ruled out with future higher-quality timing data. The results presented here aim at constraining the current modeling of tides and TTVs for TOI-2109b, helping us further understand light-curve changes associated with the long-term evolution of ultra-short-period planets.}, archive = {J_ApJ}, author = {Jaime A. Alvarado-Montes and Mario Sucerquia and Jorge I. Zuluaga and Christian Schwab}, doi = {10.3847/1538-4357/ade057}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {66}, shortjournal = {The Astrophys. J.}, title = {Orbital decay of the ultra-hot jupiter TOI-2109b: Tidal constraints and transit-timing analysis}, volume = {988}, year = {2025}, }
• (2025). The hourglass simulation: A catalog for the roman high-latitude time-domain core community survey. ApJ, 988(1), 65. (www)

  @article{ , abstract = {We present a simulation of the time-domain catalog for the Nancy Grace Roman Space Telescope’s High-Latitude Time-Domain Core Community Survey. This simulation, called the Hourglass simulation, uses the most up-to-date spectral energy distribution models and rate measurements for 10 extragalactic time-domain sources. We simulate these models through the design reference Roman Space Telescope survey: four filters per tier, a five-day cadence, over 2 yr, a wide tier of 19 deg 2 , and a deep tier of 4.2 deg 2 , with ∼20% of those areas also covered with prism observations. We find that a science-independent Roman time-domain catalog, assuming a signal-to-noise ratio at a max of >5, would have approximately 21,000 Type Ia supernovae, 40,000 core-collapse supernovae, around 70 superluminous supernovae, ∼35 tidal disruption events, three kilonovae, and possibly pair-instability supernovae. In total, Hourglass has over 64,000 transient objects, 11,000,000 photometric observations, and 500,000 spectra. Additionally, Hourglass is a useful data set to train machine learning classification algorithms. We show that SCONE is able to photometrically classify Type Ia supernovae with high precision (∼95%) to a z > 2. Finally, we present the first realistic simulations of non-Type Ia supernovae spectral time series data from Roman’s prism.}, archive = {J_ApJ}, author = {B. M. Rose and M. Vincenzi and R. Hounsell and H. Qu and L. Aldoroty and D. Scolnic and R. Kessler and P. Macias and D. Brout and M. Acevedo and R. C. Chen and S. Gomez and E. Peterson and D. Rubin and M. Sako and the Roman Supernova Project Infrastructure Team}, doi = {10.3847/1538-4357/ade1d6}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {65}, shortjournal = {The Astrophys. J.}, title = {The hourglass simulation: A catalog for the roman high-latitude time-domain core community survey}, volume = {988}, year = {2025}, }
• (2025). Thermal radiation transport with tensor trains. ApJ, 988(1), 64. (www)

  @article{ , abstract = {We present a novel tensor network algorithm to solve the time-dependent, gray thermal radiation transport equation. The method invokes a tensor train (TT) decomposition for the specific intensity. The efficiency of this approach is dictated by the rank of the decomposition. When the solution is “low rank,” the memory footprint of the specific intensity solution vector may be significantly compressed. The algorithm, following a step-then-truncate approach of a traditional discrete ordinates method, operates directly on the compressed state vector, thereby enabling large speedups for low-rank solutions. To achieve these speedups, we rely on a recently developed rounding approach based on the Gram-SVD. We detail how familiar S N algorithms for (gray) thermal transport can be mapped to this TT framework and present several numerical examples testing both the optically thick and thin regimes. The TT framework finds low-rank structure and supplies up to ≃60× speedups and ≃1000× compressions for problems demanding large angle counts, thereby enabling previously intractable S N calculations and supplying a promising avenue to mitigate ray effects.}, archive = {J_ApJ}, author = {Alex A. Gorodetsky and Patrick D. Mullen and Aditya Deshpande and Joshua C. Dolence and Chad D. Meyer and Jonah M. Miller and Luke F. Roberts}, doi = {10.3847/1538-4357/adda3f}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {64}, shortjournal = {The Astrophys. J.}, title = {Thermal radiation transport with tensor trains}, volume = {988}, year = {2025}, }
• (2025). Streams and bubbles: Tidal shaping of hydrodynamic planetary outflows. ApJ, 988(1), 63. (www)

  @article{ , abstract = {Planets, especially those close to their host stars, lose mass to atmospheric outflows, a process that is thought to shape the bimodal population of gaseous giant and rocky terrestrial exoplanets in close orbits. We model the hydrodynamic escape of planetary atmospheres in idealized, three-dimensional gas dynamic simulations in order to study their emergent morphology. As we vary the simulated system parameters, model outflows show a range of shapes from fast, isotropic outflows bounded by bow shocks to slower motion confined to thin streams. We show that a crucial factor is the role of the tidal gravity and orbiting reference frame in which planets lose mass. Flows can be characterized by the dimensionless Rossby number evaluated at the scale of the Hill sphere. Flows with a low Rossby number are significantly deviated and shaped by the stellar gravity, while those with a high Rossby number are comparatively unaffected. Rossby number alone is sufficient to predict outflow morphology as well as kinematic gradients across transit. Hydrodynamic outflows from the known exoplanet population should span a range of outflow Rossby numbers and therefore exhibit a range of morphologies. In realistic systems, shaping from gravity and hydrodynamics alone can be supplemented by the effects of stellar-wind collisions and magnetic stresses.}, archive = {J_ApJ}, author = {Morgan MacLeod and Antonija Oklopčić and Fabienne Nail and Dion Linssen}, doi = {10.3847/1538-4357/ade0b7}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {63}, shortjournal = {The Astrophys. J.}, title = {Streams and bubbles: Tidal shaping of hydrodynamic planetary outflows}, volume = {988}, year = {2025}, }
• (2025). Hyperactive repeating fast radio bursts from rotation-modulated starquakes on magnetars. ApJ, 988(1), 62. (www)

  @article{ , abstract = {The nondetection of periodicity related to rotation challenges magnetar models for fast radio bursts (FRBs) with FRB emission from close to the magnetar surface. Moreover, a bimodal distribution of the burst waiting times is widely observed in hyperactive FRBs, a significant deviation from the exponential distribution expected from stationary Poisson processes. By combining the epidemic-type aftershock sequence earthquake model and the rotating vector model involving the rotation of the magnetar and orientations of the spin and magnetic axes, we find that starquake events modulated by the rotation of FRB-emitting magnetar can explain the bimodal distribution of FRB waiting times, as well as the nondetection of periodicity in hyperactive repeating FRBs. We analyze data from multiple FRB sources, demonstrating that differences in waiting time distributions, and to some extent, observed energies can be explained by varying parameters related to geometric properties of the magnetar FRB emission and starquake dynamics. Our results show that the assumption that all FRBs are repeaters is compatible with our model. Notably, we find that hyperactive repeaters tend to have small magnetic inclination angles in order to hide their periodicity. We also show that our model can reproduce the waiting time distribution of a pulsar phase of the galactic magnetar SGR J1935+2154 with a larger inclination angle than the hyperactive repeaters, which could explain the detection of spin period and the relatively low observed energy for FRBs from the magnetar. The spin periods of hyperactive repeaters are not well constrained, but most likely fall in the valley region between the two peaks of the waiting time distributions.}, archive = {J_ApJ}, author = {Jia-Wei Luo and Jia-Rui Niu and Wei-Yang Wang and Yong-Kun Zhang and De-Jiang Zhou and Heng Xu and Pei Wang and Chen-Hui Niu and Zhen-Hui Zhang and Shuai Zhang and Ce Cai and Jin-Lin Han and Di Li and Ke-Jia Lee and Wei-Wei Zhu and Bing Zhang}, doi = {10.3847/1538-4357/ade0b9}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {62}, shortjournal = {The Astrophys. J.}, title = {Hyperactive repeating fast radio bursts from rotation-modulated starquakes on magnetars}, volume = {988}, year = {2025}, }
• (2025). SN 2023ixf in the pinwheel galaxy m101: From shock breakout to the nebular phase. ApJ, 988(1), 61. (www)

  @article{ , abstract = {We present photometric and spectroscopic observations of supernova SN 2023ixf covering from day 1 to 442 days after explosion. SN 2023ixf reached a peak V -band absolute magnitude of −18.2 ± 0.07, and light curves show that it has a relatively short “plateau” phase (∼72 days), and can be classified either as an SN IIL or a transitional event between IIP and IIL. Early-time spectra of SN 2023ixf exhibit strong, very narrow emission lines from ionized circumstellar matter (CSM), possibly indicating a Type IIn classification. But these flash/shock-ionization emission features faded after the first week and the spectrum evolved in a manner similar to that of typical Type II SNe, unlike the case of most genuine SNe IIn in which the ejecta interact with CSM for an extended period of time and develop intermediate-width emission lines. We compare observed spectra of SN 2023ixf with various model spectra to understand the physics behind SN 2023ixf. Our nebular spectra (between 200 and 400 days) match best with the model spectra from a 15 M ⊙ progenitor that experienced enhanced mass loss a few years before explosion. A last-stage mass-loss rate of \dot{M}=0.01\,{M}_{\odot }\,{\mathrm{yr}}^{-1} from the r1w6 model matches best with the early-time spectra, higher than \dot{M}\approx 2.4\times 1{0}^{-3}\,{M}_{\odot }\,{\mathrm{yr}}^{-1} derived from the ionized H α luminosity at 1.58 days. We also use SN 2023ixf as a distance indicator and fit the light curves to derive the Hubble constant by adding SN 2023ixf to the existing sample; we obtain {H}_{0}=73.{1}_{-3.50}^{+3.68} km s −1 Mpc −1 , consistent with the results from SNe Ia and many other independent methods.}, archive = {J_ApJ}, author = {WeiKang Zheng and Luc Dessart and Alexei V. Filippenko and Yi Yang and Thomas G. Brink and Thomas de Jaeger and Sergiy S. Vasylyev and Schuyler D. Van Dyk and Kishore C. Patra and Wynn V. Jacobson-Galán and Gabrielle E. Stewart and Efrain Alvarado and Veda Arikatla and Pallas Beddow and Andreas Betz and Emma Born and Kate Bostow and Adam J. Burgasser and Osmin Caceres and Evan M. Carrasco and Elma Chuang and Asia DeGraw and Elinor L. Gates and Eli Gendreau-Distler and Cooper Jacobus and Connor Jennings and Preethi R. Karpoor and Paul Lynam and Ann Mina and Katherine Mora and Neil Pichay and Jyotsna Ravi and Jon Rees and R. Michael Rich and Sophia Risin and Nathan R. Sandford and Alessandro Savino and Emma Softich and Christopher A. Theissen and Edgar P. Vidal and William Wu and Yoomee Zeng}, doi = {10.3847/1538-4357/ade0bf}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {61}, shortjournal = {The Astrophys. J.}, title = {SN 2023ixf in the pinwheel galaxy m101: From shock breakout to the nebular phase}, volume = {988}, year = {2025}, }
• (2025). The samples and binary fractions of red supergiants in m31 and m33 by the HST observations. ApJ, 988(1), 60. (www)

  @article{ , abstract = {The binarity of red supergiants (RSGs) influences their evolution and the fate of supernovae. We investigate the binary fraction of RSGs in the Andromeda galaxy (M31) and Triangulum galaxy (M33) using photometry from the Hubble Space Telescope (HST), which offers high spatial resolution to resolve more RSGs. A preliminary step involves identifying a reliable and complete RSG sample using the F110W − F160W versus F160W diagram, yielding 2612 RSGs from the Panchromatic Hubble Andromeda Treasury (PHAT) survey of M31 and 3294 RSGs from the Panchromatic Hubble Andromeda Treasury: Triangulum Extended Region survey of M33. These samples suggest total RSG populations in M31 and M33 of 6563 and 7572, respectively. These estimates significantly exceed previous ones from the ground-based observations, an increase attributed to the superior spatial resolution of the HST. The stellar parameters of these RSGs, including effective temperature ( T eff ), radius ( R ), and luminosity ( L ), are derived by fitting their spectral energy distribution (SED) across optical and near-infrared bands. Binary candidates are identified by detecting ultraviolet excesses in their SEDs compared to the single-star RSG model prediction. The binary fraction is determined to be 33.4% ± 0.9% for M31 and 30.9% ± 0.8% for M33. For more luminous RSGs with log L / L ⊙ > 4.0, the binary fraction decreases to 31.6% ± 1.9% in M31 and increases to 34.7% ± 1.8% in M33, respectively. These results are in good agreement with predictions from the Binary Population and Spectral Synthesis binary evolution model.}, archive = {J_ApJ}, author = {Min Dai and Shu Wang and Biwei Jiang and Ying Li}, doi = {10.3847/1538-4357/ade156}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {60}, shortjournal = {The Astrophys. J.}, title = {The samples and binary fractions of red supergiants in m31 and m33 by the HST observations}, volume = {988}, year = {2025}, }
• (2025). Joint modeling of quasar variability and accretion disk reprocessing using latent stochastic differential equations. ApJ, 988(1), 59. (www)

  @article{ , abstract = {Quasars are bright active galactic nuclei powered by the accretion of matter around supermassive black holes at the center of galaxies. Their stochastic brightness variability depends on the physical properties of the accretion disk and black hole. The upcoming Rubin Observatory Legacy Survey of Space and Time (LSST) is expected to observe tens of millions of quasars, so there is a need for efficient techniques like machine learning that can handle the large volume of data. Quasar variability is believed to be driven by an X-ray corona, which is reprocessed by the accretion disk and emitted as UV/optical variability. We are the first to introduce an auto-differentiable simulation of the accretion disk and reprocessing. We use the simulation as a direct component of our neural network to jointly model the driving variability and reprocessing, trained with supervised learning on simulated LSST-like 10 yr quasar light curves. We encode the light curves using a transformer encoder, and the driving variability is reconstructed using latent stochastic differential equations, a physically motivated generative deep learning method that can model continuous-time stochastic dynamics. By embedding the physical processes of the driving signal and reprocessing into our network, we achieve a model that is more robust and interpretable. We demonstrate that our model outperforms a Gaussian process regression baseline and can infer accretion disk parameters and time delays between wave bands, even for out-of-distribution driving signals. Our approach provides a powerful framework that can be adapted to solve other inverse problems in multivariate time series.}, archive = {J_ApJ}, author = {Joshua Fagin and James Hung-Hsu Chan and Henry Best and Matthew O’Dowd and K. E. Saavik Ford and Matthew J. Graham and Ji Won Park and V. Ashley Villar}, doi = {10.3847/1538-4357/addabc}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {59}, shortjournal = {The Astrophys. J.}, title = {Joint modeling of quasar variability and accretion disk reprocessing using latent stochastic differential equations}, volume = {988}, year = {2025}, }
• (2025). Spectroscopic study of globular and fuzzy clusters in lenticular galaxy NGC 1023. ApJ, 988(1), 58. (www)

  @article{ , abstract = {We here report the results from spectroscopic observations of a sample of 26 globular cluster (GC) and 21 faint fuzzy (FF) candidates in the lenticular galaxy NGC 1023 using the 10.4 m Gran Telescopio Canarias. Using the recessional velocities and stellar absorption features, we determine that 18 and 9 of the observed candidates are bona fide GCs and FFs, respectively. The majority of the rejected FF candidates are background emission line galaxies for which we determine their redshifts. We used the spectroscopic data to determine velocity, age, metallicity, and extinction of all bona fide clusters. We find that FFs are clearly younger (age = 7–9 Gyr) than GCs (age > 10 Gyr). Both kinds of clusters in this galaxy are metal-rich ([Fe/H] = −0.58 ± 0.33). The ages and metallicities of individual FFs reported here are the first such measurements in any galaxy and agree with the previously reported measurement on stacked spectrum. The kinematical analysis reaffirms that the FFs belong to the disk of the galaxy, suggesting that their progenitors are most likely massive, compact disk clusters that have been able to survive for long timescales. We propose that the fuzzy appearance of FFs as compared to the GCs is a consequence of the dynamical evolution of their progenitor super star clusters in the disks of low-mass galaxies.}, archive = {J_ApJ}, author = {M. A. López-Santamaría and Y. D. Mayya and Luis Lomelí-Núñez and L. H. Rodríguez-Merino and Jairo A. Alzate and Arianna Cortesi and P. A. Ovando and D. Rosa-González}, doi = {10.3847/1538-4357/addc6d}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {58}, shortjournal = {The Astrophys. J.}, title = {Spectroscopic study of globular and fuzzy clusters in lenticular galaxy NGC 1023}, volume = {988}, year = {2025}, }
• (2025). SHELLQs. bridging the gap: JWST unveils obscured quasars in the most luminous galaxies at z > 6. ApJ, 988(1), 57. (www)

  @article{ , abstract = {The unprecedented sensitivity of the James Webb Space Telescope (JWST) has uncovered a surprisingly abundant population of mildly obscured, low-luminosity active galactic nuclei (AGNs) in the epoch of reionization (EoR). However, the link between these objects and classical unobscured quasars remains a mystery. Here we report the discovery of obscured quasars hosted by the most luminous galaxies at z > 6, possibly bridging the gap between the two AGN populations. The 13 objects presented here were originally selected from a rest-frame ultraviolet (UV) imaging survey over >1000 deg 2 , and were known to have luminous (>10 43 erg s −1 ) Ly α emission. With JWST/NIRSpec follow-up observations, we found that 7 out of 11 objects with narrow Ly α exhibit a broad component in H I Balmer lines and He I lines, but not in [O III ] and other forbidden lines. Mild dust obscuration (0 < A V < 3) is inferred from the Balmer decrements. The estimated intrinsic luminosities suggest that our broad-line (BL) objects are the long-sought UV-obscured counterparts of luminous quasars in the EoR. They host supermassive black holes (SMBHs) with masses 10 7.8−9.1 M ⊙ , undergoing sub-Eddington to Eddington accretion. Most of the BL objects are spatially unresolved and are close to “little red dots” with their blue rest-UV and red rest-optical colors. We estimate the AGN number density among similarly luminous Ly α emitters to be larger than 2 × 10 −8 Mpc −3 . This density is comparable to that of classical quasars with similar continuum luminosities, suggesting that a substantial fraction of active SMBHs are obscured in the EoR and have been overlooked in past rest-UV surveys.}, archive = {J_ApJ}, author = {Yoshiki Matsuoka and Masafusa Onoue and Kazushi Iwasawa and Kentaro Aoki and Michael A. Strauss and John D. Silverman and Xuheng Ding and Camryn L. Phillips and Masayuki Akiyama and Junya Arita and Masatoshi Imanishi and Takuma Izumi and Nobunari Kashikawa and Toshihiro Kawaguchi and Satoshi Kikuta and Kotaro Kohno and Chien-Hsiu Lee and Tohru Nagao and Ayumi Takahashi and Yoshiki Toba}, doi = {10.3847/1538-4357/addf4e}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {57}, shortjournal = {The Astrophys. J.}, title = {SHELLQs. bridging the gap: JWST unveils obscured quasars in the most luminous galaxies at z > 6}, volume = {988}, year = {2025}, }
• (2025). Formation and early evolution of protoplanetary disks under nonuniform cosmic-ray ionization. ApJ, 988(1), 56. (www)

  @article{ , abstract = {Angular momentum transport by magnetic fields is important for formation and evolution of protoplanetary disks. The effects of magnetic fields are suppressed due to nonideal magnetohydrodynamic (MHD) effects such as ambipolar diffusion and Ohmic dissipation, which depend on the degree of ionization. Cosmic rays (CRs) are the primary source of ionization in star-forming clouds, and their distribution is nonuniform as it is affected by gas density and magnetic fields. Therefore, CRs, magnetic fields, and gas interact with each other. In this work, we develop a new fully implicit CR transport module in Athena++ and perform 3D simulations of disk formation from collapse of molecular cloud cores. Since CRs are strongly attenuated in the dense gas at the disk scale, distribution of magnetic fields is considerably altered compared to conventional models assuming a uniform ionization rate. While the total magnetic fluxes accreted onto the disks remain similar as the gas outside the disks remains sufficiently ionized and well coupled, the magnetic fields in the disks are less twisted due to the stronger nonideal MHD effects. As a consequence, magnetic angular momentum transport is strongly suppressed at the disk scale, resulting in more gravitationally unstable disks with more prominent spiral arms. Our simulations demonstrate the influence of nonuniform ionization resulting from CR transport and attenuation on the disk formation and evolution.}, archive = {J_ApJ}, author = {Erika Nishio and Kengo Tomida and Yuki Kudoh and Shigeo S. Kimura}, doi = {10.3847/1538-4357/addbe2}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {56}, shortjournal = {The Astrophys. J.}, title = {Formation and early evolution of protoplanetary disks under nonuniform cosmic-ray ionization}, volume = {988}, year = {2025}, }
• (2025). PHIBSS: Searching for molecular gas outflows in star-forming galaxies at z = 0.5–2.6. ApJ, 988(1), 55. (www)

  @article{ , abstract = {We present an analysis of millimeter CO observations to search for and quantify signatures of molecular gas outflows. We exploit the large sample of 0.5 < z < 2.6 galaxies observed as part of the PHIBSS1/2 surveys with the IRAM Plateau de Bure interferometer, focusing on the 154 typical massive star-forming galaxies with CO detections (mainly CO(3–2), but including also CO(2–1) and CO(6–5)) at signal-to-noise ratio (SNR) > 1.5 and available properties (stellar mass, star formation rate or SFR, size) from ancillary data. None of the individual spectra exhibit a compelling signature of CO outflow emission, even at high SNR > 7. To search for fainter outflow signatures, we carry out an analysis of stacked spectra, including the full sample, as well as subsets, split in terms of stellar mass, redshift, inclination, offset in SFR from the main sequence, and active galactic nuclei activity. None of the physically motivated subsamples shows any outflow signature. We report a tentative detection in a subset statistically designed to maximize outflow signatures. We derive upper limits on molecular gas outflow rate and mass loading factors η based on our results and find η ≤ 2.2–35.4, depending on the subsample. Much deeper CO data and observations of alternative tracers are needed to decisively constrain the importance of the cold molecular gas component of outflows relative to other gas phases.}, archive = {J_ApJ}, author = {Capucine Barfety and Jean-Baptiste Jolly and Natascha M. Förster Schreiber and Linda J. Tacconi and Reinhard Genzel and Giulia Tozzi and Andreas Burkert and Jianhang Chen and Françoise Combes and Ric Davies and Frank Eisenhauer and Juan M. Espejo Salcedo and Rodrigo Herrera-Camus and Lilian L. Lee and Minju M. Lee and Daizhong Liu and Dieter Lutz and Thorsten Naab and Roberto Neri and Amit Nestor Shachar and Stavros Pastras and Claudia Pulsoni and Sedona H. Price and Alvio Renzini and Karl Schuster and Taro T. Shimizu and Amiel Sternberg and Eckhard Sturm and Hannah Übler and Stijn Wuyts}, doi = {10.3847/1538-4357/addc6f}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {55}, shortjournal = {The Astrophys. J.}, title = {PHIBSS: Searching for molecular gas outflows in star-forming galaxies at z = 0.5–2.6}, volume = {988}, year = {2025}, }
• (2025). On the effects of parameters on galaxy properties in CAMELS and the predictability of Ωm. ApJ, 988(1), 54. (www)

  @article{ , abstract = {Recent analyses of cosmological hydrodynamic simulations from CAMELS have shown that machine learning models can predict the parameter describing the total matter content of the universe, Ω m , from the features of a single galaxy. We investigate the statistical properties of two of these simulation suites, IllustrisTNG and ASTRID , confirming that Ω m induces a strong displacement on the distribution of galaxy features. We also observe that most other parameters have little to no effect on the distribution, except for the stellar-feedback parameter A SN1 , which introduces some near-degeneracies that can be broken with specific features. These two properties explain the predictability of Ω m . We use optimal transport to further measure the effect of parameters on the distribution of galaxy properties, which is found to be consistent with physical expectations. However, we observe discrepancies between the two simulation suites, both in the effect of Ω m on the galaxy properties and in the distributions themselves at identical parameter values. Thus, although Ω m ’s signature can be easily detected within a given simulation suite using just a single galaxy, applying this result to real observational data may prove significantly more challenging.}, archive = {J_ApJ}, author = {Gabriella Contardo and Roberto Trotta and Serafina Di Gioia and David W. Hogg and Francisco Villaescusa-Navarro}, doi = {10.3847/1538-4357/addd08}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {54}, shortjournal = {The Astrophys. J.}, title = {On the effects of parameters on galaxy properties in CAMELS and the predictability of Ωm}, volume = {988}, year = {2025}, }
• (2025). Atmospheric retrieval of Subaru/IRD high-resolution spectrum of the archetype T-type brown dwarf gl 229 b*. ApJ, 988(1), 53. (www)

  @article{ , abstract = {Brown dwarfs provide a unique opportunity to study atmospheres and their physical and chemical processes with high precision, especially in temperature ranges relevant to exoplanets. In this study, we performed high-resolution ( R ∼ 70,000) spectroscopy using Subaru/IRD ( Y , J , H bands) of the T7.0p-type object Gl 229 B, the first discovered T-type brown dwarf, which orbits an M1V host star at a separation of 33 au. We conducted atmospheric retrieval on the reduced H -band spectrum using the high-resolution spectrum model compatible with automatic differentiation and GPU, ExoJAX. In contrast to previous retrieval studies on medium-resolution spectra, we obtained a C/O ratio consistent with that of the host star, aligning with the expected formation process for such a massive brown dwarf. Additionally, based on the strong constraint on temperature from the high-resolution spectrum and previously measured photometric magnitude, our analysis indicates that Gl 229 B is a binary, which was also proposed by G. M. Brandt et al. and recently confirmed by J. W. Xuan et al. Finally, we validated current molecular line lists by leveraging the obtained high-resolution, high signal-to-noise ratio spectrum of this warm (∼900 K) atmosphere. This study highlights the importance of observing companion brown dwarfs as benchmark objects for establishing characterization techniques for low-mass objects and enhancing our understanding of their atmospheres, given the wealth of available information and the relative ease of observation.}, archive = {J_ApJ}, author = {Yui Kawashima and Hajime Kawahara and Yui Kasagi and Hiroyuki Tako Ishikawa and Kento Masuda and Takayuki Kotani and Tomoyuki Kudo and Teruyuki Hirano and Masayuki Kuzuhara and Stevanus K. Nugroho and John Livingston and Hiroki Harakawa and Jun Nishikawa and Masashi Omiya and Takuya Takarada and Motohide Tamura and Akitoshi Ueda}, doi = {10.3847/1538-4357/adddbd}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {53}, shortjournal = {The Astrophys. J.}, title = {Atmospheric retrieval of Subaru/IRD high-resolution spectrum of the archetype T-type brown dwarf gl 229 b*}, volume = {988}, year = {2025}, }
• (2025). Identification of new candidate Be/X-ray binary systems in the small magellanic cloud via analysis of the S-CUBED source catalog. ApJ, 988(1), 52. (www)

  @article{ , abstract = {It has long been known that a large population of Be/X-ray binaries (BeXRBs) exists in the Milky Way’s neighboring dwarf galaxy, the Small Magellanic Cloud (SMC), due to a recent period of intense star formation. Since 2016, efforts have been made to monitor this population and identify new BeXRBs through the Swift SMC Survey (S-CUBED). S-CUBED’s weekly observation cadence has identified many new BeXRBs that exist within the SMC, but evidence suggests that more systems exist that have thus far escaped detection. A major challenge in identifying new BeXRBs is their transient nature at high-energy wavelengths, which prevents them from being detected via their X-ray emission characteristics when not in outburst. In order to identify sources that may have been missed owing to a long period of quiescence, it becomes necessary to devise methods of detection that rely on wavelengths at which BeXRBs are more persistent emitters. In this work, we attempt to use archival analysis of infrared, optical, and ultraviolet observations to identify new candidate BeXRBs that have been overlooked within the S-CUBED source catalog. Using X-ray/optical selection of source properties, unsupervised clustering, spectral energy distribution fitting to VizieR archival measurements, and ultraviolet light-curve analysis, we are able to identify six new candidate BeXRB systems that otherwise would have been missed by automated analysis pipelines. Using these results, we demonstrate the use of ultraviolet through near-infrared observational data in identifying candidate BeXRBs when they cannot be identified using their X-ray emission.}, archive = {J_ApJ}, author = {Thomas M. Gaudin and Jamie A. Kennea and M. J. Coe and Phil A. Evans}, doi = {10.3847/1538-4357/addfd1}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {52}, shortjournal = {The Astrophys. J.}, title = {Identification of new candidate Be/X-ray binary systems in the small magellanic cloud via analysis of the S-CUBED source catalog}, volume = {988}, year = {2025}, }
• (2025). Finding white dwarfs’ hidden companions using an unsupervised machine learning technique. ApJ, 988(1), 51. (www)

  @article{ , abstract = {White dwarfs (WD) with main-sequence (MS) companions are crucial probes of stellar evolution. However, due to the significant difference in their luminosities, the WD is often outshined by the MS star. The aim of this work is to find hidden companions in Gaia’s sample of WD candidates. Our methodology involves applying an unsupervised machine learning algorithm for dimensionality reduction and clustering, known as a self-organizing map (SOM), to Gaia BP/RP (XP) spectra. This strategy allows us to naturally separate WDMS binaries from single WDs from the detection of subtle red flux excesses in the XP spectra that are indicative of low-mass MS companions. We validate our approach using confirmed WDMS binaries from the Sloan Digital Sky Survey and LAMOST surveys, achieving a precision of ∼90%. We demonstrated that the luminosity of the faint companions in the missed systems is ∼50 times lower than that of their WD primaries. Applying our SOM to 90,667 sources, we identify 993 WDMS candidates, 506 of which have not been previously reported in the literature. If confirmed, our sample will increase the known WDMS binaries by 20%. Additionally, we use the Virtual Observatory Spectral Energy Distribution Analyzer tool to refine and parameterize a “golden sample” of 136 WDMS binaries through multiwavelength photometry and a two-body spectral energy distribution fitting. These high-confidence WDMS binaries are composed of low-mass WDs (∼0.42 M ⊙ ), with cool MS companions (∼2800 K). Finally, 13 systems exhibit periodic variability consistent with eclipsing binaries, making them prime targets for further follow-up observations.}, archive = {J_ApJ}, author = {Xabier Pérez-Couto and Minia Manteiga and Eva Villaver}, doi = {10.3847/1538-4357/addfd7}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {51}, shortjournal = {The Astrophys. J.}, title = {Finding white dwarfs’ hidden companions using an unsupervised machine learning technique}, volume = {988}, year = {2025}, }
• (2025). Driven phase-mixed alfvén waves in a partially ionized solar plasma. ApJ, 988(1), 50. (www)

  @article{ , abstract = {Phase mixing has long been understood to be a viable mechanism for expediting the dissipation of Alfvén wave energy resulting in the subsequent heating of the solar atmosphere. To fulfill the conditions necessary for phase mixing to occur, we consider the cross-field gradient in the Alfvén speed as a free parameter in our model. Using a single-fluid description of a partially ionized chromospheric plasma, we explore the efficiency of damping of shear Alfvén waves subject to phase mixing when a pulse wave driver is employed. Our results demonstrate a strong dependence of the dissipation length of shear Alfvén waves on both the ionization degree of the plasma and the gradient of the Alfvén speed. When assessing the efficiency of phase mixing across various inhomogeneities, our findings indicate that waves originating from a pulse driver initially exhibit heating rates identical to those generated by a continuous wave driver. One key difference observed was that Alfvén pulses possess a lower overall decay rate, due to a change in damping profile from exponential to algebraic. This discrepancy arises from the absence of a consistent injection of energy into the base of the domain, which preserves longitudinal gradients of the magnetic field perturbations more effectively. These findings demonstrate the importance of understanding the relations between the wave driver, damping mechanisms, and propagation dynamics in resolving the atmospheric heating problem.}, archive = {J_ApJ}, author = {M. McMurdo and I. Ballai and G. Verth and V. Fedun}, doi = {10.3847/1538-4357/ade303}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {50}, shortjournal = {The Astrophys. J.}, title = {Driven phase-mixed alfvén waves in a partially ionized solar plasma}, volume = {988}, year = {2025}, }
• (2025). Switchbacks near boundaries of small-scale magnetic flux ropes in the young solar wind from parker solar probe observations. ApJ, 988(1), 49. (www)

  @article{ , abstract = {The Parker Solar Probe (PSP) mission has revealed frequent occurrences of switchbacks (SBs) and small-scale magnetic flux ropes (SMFRs) as prominent structures within the solar wind. These mesoscale features are observed across all heliocentric distances, with heightened activity in the young solar wind, such as successive SMFRs, blobs, and SBs using PSP in situ observations. One study, in particular, focuses on SMFRs observed during the intervals of PSP corotating with the Sun, which suggests a similar source of the observed solar wind. In this paper, we identified SBs at the boundaries of SMFRs as a regularly observed phenomenon and found instances where SBs and SMFRs co-occur, with the significance level α < 0.05. The SMFR-related SBs—observed at the leading and trailing edges of an SMFR—exhibit well-organized axial co-orientations, with their polarity flipping, meaning the radial direction remains constrained while the transversal field reverses. Furthermore, the axial field directions of SMFR-related SBs appear to be more closely connected than to another SB that is spatially closer and are linked to the SMFR orientation. Our analysis of their relative geometry, which examines the alignment between SBs and the SMFR axis, reveals a distinct tendency emphasizing their correlation, further supporting the idea that the axes of SMFR-related SBs are presumably determined by the SMFR orientation. Observations suggest that a fraction of SBs are spatially and temporally associated with SMFRs, implying that processes related to SMFR boundaries may contribute to SB formation or that SBs tend to develop in magnetic environments shaped by SMFRs.}, archive = {J_ApJ}, author = {Kyung-Eun Choi and Oleksiy V. Agapitov and Dae-Young Lee and Forrest Mozer and Jia Huang and Lucas Colomban and Jaye L. Verniero and Nour Raouafi}, doi = {10.3847/1538-4357/ade4be}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {49}, shortjournal = {The Astrophys. J.}, title = {Switchbacks near boundaries of small-scale magnetic flux ropes in the young solar wind from parker solar probe observations}, volume = {988}, year = {2025}, }
• (2025). LATIS: Comparing galaxy and IGM tomography maps as tracers of large-scale structure and protoclusters at z ∼ 2.5. ApJ, 988(1), 48. (www)

  @article{ , abstract = {We investigate the consistency of intergalactic medium (IGM) tomography and galaxy surveys as tracers of the cosmic web and protoclusters at z ∼ 2.5. We use maps from the Ly α Tomography IMACS Survey (LATIS), which trace the distributions of Lyman-break galaxies (LBGs) and IGM Ly α absorption on ≃4 h −1 cMpc scales within the same large volume. Overall, the joint distribution of IGM absorption and LBG density is well constrained and accurately described by a simple physical model. However, we identify several exceptional locations exhibiting strong IGM absorption indicative of a massive protocluster, yet no coincident overdensity of LBGs. As discussed by Newman et al., whose results we revise using the complete LATIS survey data, these are candidate ultraviolet (UV)-dim protoclusters that may harbor distinct galaxy populations missed by rest-UV spectroscopic surveys. We present follow-up observations targeting one such candidate embedded within Antu, an extended region of IGM absorption at z = 2.685 that contains five IGM-selected protoclusters and has a total mass of 3 × 10 15 M ⊙ . Ly α emitters trace the overall structure of Antu but avoid the center of the candidate UV-dim protocluster, which also appears to contain no submillimeter-selected sources. A near-infrared spectroscopic galaxy census is needed to determine whether this large region is dominated by galaxies with reduced or absent star formation activity. This work adds to a growing and puzzling literature on discrepancies among different galaxy and IGM tracers, whose resolution promises to shed light on the early stages of environment-dependent galaxy evolution.}, archive = {J_ApJ}, author = {Andrew B. Newman and Nima Chartab and Mahdi Qezlou and Gwen C. Rudie and Guillermo A. Blanc and Daniel D. Kelson and Simeon Bird and Caitlin Casey and Enrico Congiu and Olga Cucciati and Denise Hung and Brian C. Lemaux and Victoria Pérez and Jorge Zavala}, doi = {10.3847/1538-4357/ade3c3}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {48}, shortjournal = {The Astrophys. J.}, title = {LATIS: Comparing galaxy and IGM tomography maps as tracers of large-scale structure and protoclusters at z ∼ 2.5}, volume = {988}, year = {2025}, }
• (2025). LATIS: A sample of IGM-selected protoclusters and protogroups at z ∼ 2.5. ApJ, 988(1), 47. (www)

  @article{ , abstract = {The Ly α Tomography IMACS Survey (LATIS) has produced large 3D maps of the intergalactic medium (IGM), providing a new window on the cosmic web at z ∼ 2.5. A key advantage of Ly α tomography is that it enables the discovery of overdense regions without the need to detect their galaxy members in spectroscopic surveys, circumventing possible selection biases. We use these maps to identify 37 IGM-selected overdensities as regions of strong and spatially coherent Ly α absorption. Simulations indicate that 85% of these are protoclusters, defined as the progenitors of z = 0 halos with mass M desc > 10 14 M ⊙ , and that nearly all of the rest are protogroups (10 13.5 < M desc / M ⊙ < 10 14 ). We estimate the masses and space densities of the IGM-selected overdensities and show they are in accordance with mock surveys. We investigate the LATIS counterparts of some previously reported protoclusters, including the proto-supercluster Hyperion. We identify a new component of Hyperion beyond its previously known extent. We show that the Ly α transmission of the galaxy density peaks within Hyperion is consistent with a simple physical model (the fluctuating Gunn–Peterson approximation), suggesting that active galactic nucleus feedback or other processes have not affected the large-scale gas ionization within this structure as a whole. The LATIS catalog represents an order-of-magnitude increase in the number of IGM-selected protogroups and protoclusters and will enable new investigations of the connections between galaxies and their large-scale environments at cosmic noon.}, archive = {J_ApJ}, author = {Andrew B. Newman and Mahdi Qezlou and Gwen C. Rudie and Nima Chartab and Guillermo A. Blanc and Daniel D. Kelson and Simeon Bird and Caitlin Casey and Enrico Congiu and Olga Cucciati and Denise Hung and Brian C. Lemaux and Victoria Pérez and Jorge Zavala}, doi = {10.3847/1538-4357/ade0b2}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {47}, shortjournal = {The Astrophys. J.}, title = {LATIS: A sample of IGM-selected protoclusters and protogroups at z ∼ 2.5}, volume = {988}, year = {2025}, }
• (2025). Probing chemical enrichment in extremely metal-poor galaxies. ApJ, 988(1), 46. (www)

  @article{ , abstract = {The chemical composition of galaxies offers vital insights into their formation and evolution. In particular, the relationship between helium abundance (He/H) and metallicity serves as a key diagnostic for estimating the primordial helium yield from Big Bang nucleosynthesis. We investigate the chemical enrichment history of low-metallicity galaxies, focusing especially on extremely metal-poor galaxies (EMPGs), using one-zone chemical evolution models. Adopting elemental yields from M. Limongi & A. Chieffi, our models reach He/H ∼ 0.089 at (O/H) × 10 5 < 20, yet they fall short of reproducing the elevated He/H values observed in low-redshift dwarf galaxies. In contrast, the observed Fe/O ratios in EMPGs are successfully reproduced using both the K. Nomoto et al. and M. Limongi & A. Chieffi yield sets. To address the helium discrepancy, we incorporate supermassive stars (SMSs) as Population III stars in our models. We find that SMSs can significantly enhance He/H, depending on the mass-loss prescription. When only 10% of the SMS mass is ejected, the model yields the steepest slope in the (O/H) × 10 5 –He/H relation. Alternatively, if the entire outer envelope up to the CO core is expelled, the model can reproduce the high He/H ratios observed in high-redshift galaxies (He/H > 0.1). Additionally, these SMS-enriched models also predict elevated N/O ratios, in agreement with recent JWST observations of the early Universe.}, archive = {J_ApJ}, author = {Keita Fukushima and Kentaro Nagamine and Akinori Matsumoto and Yuki Isobe and Masami Ouchi and Takayuki R. Saitoh and Yutaka Hirai}, doi = {10.3847/1538-4357/add690}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {46}, shortjournal = {The Astrophys. J.}, title = {Probing chemical enrichment in extremely metal-poor galaxies}, volume = {988}, year = {2025}, }
• (2025). Inferring the density and membership of stellar streams with flexible models: The GD-1 stream in gaia data release 3. ApJ, 988(1), 45. (www)

  @article{ , abstract = {Stellar streams provide one of the most promising avenues for constraining the global mass distribution of the Milky Way and the nature of dark matter (DM). The stream stars’ kinematic “track” enables inference of large-scale properties of the DM distribution, while density variations and anomalies provide information about local DM clumps (e.g., from DM subhalos). A full accounting of the density tracks and substructures within all >100 Milky Way stellar streams will therefore enable powerful new constraints on DM. Here, we present a new, flexible framework for modeling stellar stream density and membership. With it, one can empirically model a given stream in a variety of coordinate spaces (e.g., on-sky position and velocity) using probability distributions, thereby generating membership probabilities. The most significant improvement over previous methods is the inclusion of off-track or non-Gaussian components to the stream density, meaning we can capture anomalous features (such as the GD-1 steam’s spur). We test our model on GD-1, where we characterize previously known features and provide the largest catalog of probable member stars to date (1689 stars). We then use the derived model to provide measurements of GD-1’s density and kinematic tracks, velocity dispersion, as well as its initial and current mass. Our framework (built on JAX and numpyro ) provides a path toward uniform analysis of all Milky Way streams, enabling tight constraints on the Galactic mass distribution and its dark matter.}, archive = {J_ApJ}, author = {Kiyan Tavangar and Adrian M. Price-Whelan}, doi = {10.3847/1538-4357/addd1c}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {45}, shortjournal = {The Astrophys. J.}, title = {Inferring the density and membership of stellar streams with flexible models: The GD-1 stream in gaia data release 3}, volume = {988}, year = {2025}, }
• (2025). Spatially resolved modeling of galactic hα emission for galaxy clustering. ApJ, 988(1), 44. (www)

  @article{ , abstract = {Near-infrared spectroscopic surveys target high-redshift emission-line galaxies (ELGs) to probe cosmological scenarios. Understanding the clustering properties of ELGs is essential to derive optimal constraints. We present a simple radiative transfer model for spatially resolved galactic H α emission, which includes emission from the warm-hot diffuse interstellar medium. The atomic-level populations are in steady state and computed in the coronal approximation. The model is applied to multiple IllustrisTNG simulations in the redshift range 1 ≤ z ≤ 2 to produce the luminosity function (LF) and the halo occupation distribution (HOD). Collisional processes account for a significant fraction (≈40%) of the total H α luminosity ( L H α ). Our LFs are in reasonable agreement with measurements from H α surveys if a uniform extinction of 0.3 < A H α < 0.85 mag is assumed. Our HOD is consistent with that of the Euclid Flagship galaxy mock up to differences that can be attributed to baryonic feedback, which is absent from the latter. When H α luminosities are computed from an empirical relation between L H α and the total star formation rate, the resulting LFs are in tension with previous observations. Our approach can be extended to other atomic lines, which should be helpful for the mining of high-redshift galaxy spectra in forthcoming surveys.}, archive = {J_ApJ}, author = {Ivan Rapoport and Vincent Desjacques and Gabriele Parimbelli and Ehud Behar and Martin Crocce}, doi = {10.3847/1538-4357/adde4c}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {44}, shortjournal = {The Astrophys. J.}, title = {Spatially resolved modeling of galactic hα emission for galaxy clustering}, volume = {988}, year = {2025}, }
• (2025). Radiation and magnetic pressure support in accretion disks around supermassive black holes and the physical origin of the extreme-ultraviolet to soft X-ray spectrum. ApJ, 988(1), 43. (www)

  @article{ , abstract = {We present the results of four 3D radiation magnetohydrodynamic simulations of accretion disks around a 10 8 solar mass black hole, which produce the far-ultraviolet spectrum peak and demonstrate a robust physical mechanism for producing the extreme-ultraviolet to soft X-ray power-law continuum component. The disks are fed from rotating tori and reach accretion rates ranging from 0.03 to 4 times the Eddington value. The disks become radiation pressure or magnetic pressure dominated, depending on the relative timescales of radiative cooling and gas inflow. Magnetic pressure supported disks can form with or without net poloidal magnetic fields, as long as the inflowing gas can cool quickly enough, which can typically happen when the accretion rate is low. We calculate the emerging spectra from these disks using multigroup radiation transport with realistic opacities and find that they typically peak around 10 eV. At accretion rates close to or above the Eddington limit, a power-law component can appear for photon energies between 10 eV and 1 keV, with a spectral slope varying between L ν ∝ ν −1 and ν −2 , comparable to what is observed in radio-quiet quasars. A disk with a 3% Eddington accretion rate does not exhibit this component. These high-energy photons are produced in an optically thick region ≈30 ∘ –45 ∘ from the disk midplane, by compressible bulk Comptonization within the converging accretion flow. Strongly magnetized disks that have a very small surface density will produce a spectrum that is very different from what is observed.}, archive = {J_ApJ}, author = {Yan-Fei Jiang and Omer Blaes and Ish Kaul and Lizhong Zhang}, doi = {10.3847/1538-4357/addecb}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {43}, shortjournal = {The Astrophys. J.}, title = {Radiation and magnetic pressure support in accretion disks around supermassive black holes and the physical origin of the extreme-ultraviolet to soft X-ray spectrum}, volume = {988}, year = {2025}, }
• (2025). Spectroastrometry and reverberation mapping of active galactic nuclei. II. measuring geometric distances and black hole masses of four nearby quasars. ApJ, 988(1), 42. (www)

  @article{ , abstract = {The geometric distances of active galactic nuclei (AGNs) are challenging to measure because of their exceptionally compact structure, yet vast cosmic distances. A combination of spectroastrometry and reverberation mapping (SARM) of broad-line regions (BLRs) constitutes a novel means to probe the geometric distance of AGNs, which has recently become practically feasible owing to successful interferometric observations with the Very Large Telescope Interferometer/GRAVITY. Here, we perform SARM analysis of four nearby quasars: Mrk 509, PDS 456, 3C 273, and NGC 3783. Results for the former two are reported for the first time, and the latter two are revisited using our improved BLR dynamical modeling that includes the radial-dependent responsivity of BLRs. This allows us to self-consistently account for the emissivity weighting of the BLR in spectroastrometry and responsivity weighting in reverberation mapping. We obtain angular-diameter distances of the four quasars, from which we derive a Hubble constant of {H}_{0}=6{9}_{-10}^{+12}\,{\rm{km}}\,{{\rm{s}}}^{-1}\,{{\rm{Mpc}}}^{-1} . Although this constitutes a large uncertainty for a measurement of H 0 , it is anticipated that the precision will improve to a competitive level once a greater number of AGNs are accessible following the upgrade of GRAVITY in the near future. From SARM analysis, the black hole masses of the four quasars are also measured with the statistical uncertainty ranging from 0.06 to 0.23 dex, consistent with the correlations between black hole masses and properties of the host bulges.}, archive = {J_ApJ}, author = {Yan-Rong Li and Jinyi Shangguan and Jian-Min Wang and Ric Davies and Daryl J. D. Santos and Frank Eisenhauer and Yu-Yang Songsheng and Hartmut Winkler and Jesús Aceituno and Hua-Rui Bai and Jin-Ming Bai and Michael S. Brotherton and Yixian Cao and Yong-Jie Chen and Pu Du and Feng-Na Fang and Jia-Qi Feng and Helmut Feuchtgruber and Natascha M. Förster Schreiber and Yi-Xin Fu and Reinhard Genzel and Stefan Gillessen and Luis C. Ho and Chen Hu and Jun-Rong Liu and Dieter Lutz and Thomas Ott and Romain G. Petrov and Sebastian Rabien and Taro Shimizu and Eckhard Sturm and Linda J. Tacconi and Yi-Lin Wang and Zhu-Heng Yao and Shuo Zhai and Hao Zhang and Yi-Peng Zhao and Yu Zhao and (SARM Collaboration)}, doi = {10.3847/1538-4357/addf40}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {42}, shortjournal = {The Astrophys. J.}, title = {Spectroastrometry and reverberation mapping of active galactic nuclei. II. measuring geometric distances and black hole masses of four nearby quasars}, volume = {988}, year = {2025}, }
• (2025). Bright bursts with submillisecond structures of FRB 20230607A in a highly magnetized environment. ApJ, 988(1), 41. (www)

  @article{ , abstract = {We report the observations of a repeating FRB 20230607A for 15.6 hr spanning 16 months using the Five-hundred-meter Aperture Spherical Radio Telescope with the detection of 565 bursts. We present three bright bursts with detailed temporal/spectral structures. We also report that one burst carries a narrow component with a width of only 0.3 ms, which is surrounded by broader components. This suggests that repeaters can make both narrow and broad components in one burst. With the narrow spike, we precisely measure the dispersion measure of 362.85 ± 0.15 pc cm −3 and the Faraday rotation measures (RMs) of −12249.0 ± 1.5 rad m −2 . We also analyze the statistical distribution of the burst parameters, including waiting times, temporal widths, central frequencies and frequency widths, fluences and energies, all showing typical distributions of known active repeaters. In particular, most bursts show narrow spectra with Δ ν / ν 0 = 0.125 ± 0.001. This fact, together with the narrow 0.3 ms spike, strongly suggests a magnetospheric origin of the FRB emission. Based on a predicted correlation between RM and the luminosity of a persistent radio source (PRS) by Yang et al., we predict that the PRS should have a specific luminosity of the order of 10 29 erg s −1 Hz −1 and encourage a search for such a PRS.}, archive = {J_ApJ}, author = {DeJiang Zhou and J. L. Han and Bing Zhang and WeiWei Zhu and Wei-yang Wang and Yuan-Pei Yang and Yuanhong Qu and Yong-Kun Zhang and Yi Yan and Wei-Cong Jing and Shuo Cao and Jintao Xie and Xuan Yang and Shiyan Tian and Ye Li and Dongzi Li and Jia-Rui Niu and Zi-Wei Wu and Qin Wu and Yi Feng and Fayin Wang and Pei Wang}, doi = {10.3847/1538-4357/addfdb}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {41}, shortjournal = {The Astrophys. J.}, title = {Bright bursts with submillisecond structures of FRB 20230607A in a highly magnetized environment}, volume = {988}, year = {2025}, }
• (2025). SLAMS-propelled electron acceleration at high-mach-number astrophysical shocks. ApJ, 988(1), 40. (www)

  @article{ , abstract = {Short large-amplitude magnetic structures (SLAMS) are frequently detected during spacecraft crossings over Earth's bow shock. We investigate the existence of such structures at astrophysical shocks, where they could result from the steepening of cosmic-ray (CR) driven waves. Using kinetic particle-in-cell simulations, we study the growth of SLAMS and the appearance of associated transient shocks in the upstream region of parallel, nonrelativistic, high-Mach-number collisionless shocks. We find that high-energy CRs significantly enhance the transverse magnetic field within SLAMS, producing highly inclined field lines. As SLAMS are advected toward the shock, these field lines form an intermittent superluminal configuration that traps magnetized electrons at fast shocks. Due to their oscillatory nature, SLAMS are periodically separated by subluminal gaps with lower transverse magnetic field strength. In these regions, electrons diffuse and accelerate by bouncing between the shock and the approaching SLAMS' region through a mechanism that we call quasi-periodic shock acceleration (QSA). We analytically derive the distribution of electrons accelerated via QSA, f ( p ) ∼ p [−4.7,−5.7] , which agrees well with the simulation spectra. We find that the electron power law remains steep until the end of our longest runs, providing a possible explanation for the steep electron spectra observed at least up to GeV energies in young and fast supernova remnants.}, archive = {J_ApJ}, author = {Vladimir Zeković and Anatoly Spitkovsky and Zachary Hemler}, doi = {10.3847/1538-4357/ade05f}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {40}, shortjournal = {The Astrophys. J.}, title = {SLAMS-propelled electron acceleration at high-mach-number astrophysical shocks}, volume = {988}, year = {2025}, }
• (2025). The structural and kinematical properties of NGC 5634, a globular cluster associated with the sagittarius dwarf galaxy?. ApJ, 988(1), 39. (www)

  @article{ , abstract = {We investigate the origin of NGC 5634 through a comprehensive analysis of its morphology, kinematics, and dynamics. Utilizing data from the DESI Legacy Survey, we refined its fundamental parameters (age τ = 12.8 ± 0.3 Gyr, metallicity [Fe/H] = −1.8 ± 0.1 dex, distance modulus dm = 17.0 ± 0.1 mag) and constructed a matched-filter template based on the combination of these parameters to search for extra-tidal structures. However, no significant features were detected above a 3 σ signal-to-noise threshold, which limits our ability to further investigate the association between NGC 5634 and the Sagittarius (Sgr) stream based on morphological evidence. Incorporating GAIA data, we further examine the orbital path of NGC 5634. We found that its orbit only briefly intersects with the Sgr stream and diverges significantly over long-term integrations. This behavior contrasts with that of confirmed Sgr-associated clusters, whose orbits remain closely aligned with the stream throughout their orbital evolution. Additionally, NGC 5634 exhibits a relatively shorter semimajor axis and smaller apocenter and pericenter distances compared to Sgr clusters. These orbital characteristics are more consistent with clusters associated with the Gaia–Sausage–Enceladus (GSE) or the Helmi streams. From a dynamical perspective, in the L z – E space, NGC 5634 is also distinctly different from Sgr clusters and aligns more closely with the GSE and Helmi regions. Taken together, these findings do not support a strong connection between NGC 5634 and the Sgr dSph, but instead suggest a potential association with another progenitor system, such as GSE or Helmi stream. Nevertheless, further evidence is needed to definitively establish its origin.}, archive = {J_ApJ}, author = {Shouzhi Wang and Jundan Nie and Biwei Jiang and Hao Tian and Chao Liu and Ying-Hua Zhang}, doi = {10.3847/1538-4357/ade0b6}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {39}, shortjournal = {The Astrophys. J.}, title = {The structural and kinematical properties of NGC 5634, a globular cluster associated with the sagittarius dwarf galaxy?}, volume = {988}, year = {2025}, }
• (2025). Nonparallel wave propagation in an asymmetric magnetic slab. ApJ, 988(1), 38. (www)

  @article{ , abstract = {Theoretical and numerical analyses of the behavior of magnetohydrodynamic (MHD) waves in solar atmospheric structures have a vital role in understanding the plasma dynamics of the Sun. Magneto-helioseismology is indebted to the insight gained from simple magnetic slab structures accompanied by varying conditions within the slab and its environment. This paper builds on the existing literature on these structures by presenting an analytical approach to deriving the dispersion relation for MHD wave propagation in a nonparallel case. Analogous to the parallel case, a plethora of modes emerges that can be classified into quasi-kink or quasi-sausage, body or surface, as well as fast or slow waves. The slab itself can be viewed as thin or wide similarly to previous works, however due to the nonparallel condition it can also be categorised as short or long in the direction of the tilt of the wavevector. This is the analog of the thin or wide slab classification in the parallel direction, expanding our established knowledge regarding propagating MHD waves in magnetic slabs. The variance of the wavenumber along the nonparallel dimension brings to light a number of intriguing features, such as modes changing character with variation of the angle of the wavevector while the propagation speed remains the same. Further new information is provided by the newly derived classification limits, u ± , which act as a form of generalised Alfvén and sound speeds in the dispersion relation.}, archive = {J_ApJ}, author = {Antreas Tsiapalis and Noémi Kinga Zsámberger and Balázs Asztalos and Robert Erdélyi}, doi = {10.3847/1538-4357/addc69}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {38}, shortjournal = {The Astrophys. J.}, title = {Nonparallel wave propagation in an asymmetric magnetic slab}, volume = {988}, year = {2025}, }
• (2025). Rethinking habitability using biogenic precursors: Formaldehyde in millimeter molecular clouds of the inner galaxy. ApJ, 988(1), 36. (www)

  @article{ , abstract = {We present a comprehensive study of formaldehyde (H 2 CO) absorption and radio recombination line (H 110 α ) emission in 215 molecular clouds from the Bolocam Galactic Plane Survey, observed using the Nanshan 25 m radio telescope. H 2 CO was detected in 88 sources (40.93%) with 59 being new detections, while H 110 α emission was found in only 11 sources (5.12%), all coincident with H 2 CO absorption. There exists a correlation of H 2 CO fluxes with millimeter fluxes below a 3 Jy threshold and an increased dispersion above it, suggesting the sub-cosmic microwave background cooling of H 2 CO. Cross-matching with kinematic distance catalogs revealed H 2 CO spanning galactocentric distances from 0.216 to 10.769 kpc, with column densities ranging from 7.82 × 10 11 to 6.69 × 10 14 cm −2 . A significant inverse correlation was observed between H 2 CO detection fraction and galactocentric distance, suggesting enhanced star-forming activity closer to the Galactic Center. These findings challenge traditional Galactic Habitable Zone (GHZ) models by demonstrating the presence of biogenic precursors in the inner Galaxy, shielded within dense molecular clouds. Our results underscore the importance of incorporating chemical tracers such as H 2 CO, alongside physical constraints to refine the boundaries of the GHZ and advance the research of prebiotic chemistry in the Milky Way.}, archive = {J_ApJ}, author = {N. B. Baharin and A. A. Nazri and Z. Rosli and Z. Z. Abidin and H. A. Tajuddin and J. Esimbek and D. L. Li and X. Tang}, doi = {10.3847/1538-4357/add691}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {36}, shortjournal = {The Astrophys. J.}, title = {Rethinking habitability using biogenic precursors: Formaldehyde in millimeter molecular clouds of the inner galaxy}, volume = {988}, year = {2025}, }
• (2025). Evolutionary period changes for 25 X-ray binaries and the measurement of an empirical universal law for angular momentum loss in accreting binaries. ApJ, 988(1), 35. (www)

  @article{ , abstract = {I measure and collect timings of phase markers (like eclipse times) for the orbits of 25 X-ray binaries (XRBs) so as to calculate the steady evolutionary period change ( \dot{P} ). I combine these with my observed \dot{P} measures from 52 cataclysmic variables (CVs). Further, I subtract out the contributions from gravitational radiation ( {\dot{P}}_{{\rm{GR}}} ) and mass transfer ( {\dot{P}}_{{\rm{mt}}} ), deriving the period change from the residual unknown angular momentum loss ( {\dot{P}}_{{\rm{AML}}} = \dot{P} – {\dot{P}}_{{\rm{GR}}} – {\dot{P}}_{{\rm{mt}}} ). I have {\dot{P}}_{{\rm{AML}}} measures for 77 XRBs and CVs, with these being direct measures of the driver of binary evolution. The venerable magnetic braking model of binary evolution has its most fundamental predictions tested, with most systems having predictions wrong by over 1 order of magnitude. Other proposed mechanisms to explain the angular momentum loss (AML) also fail, so we are left with no known mechanism that dominates the AML. An alternative path to the AML law is empirical, where my {\dot{P}}_{{\rm{AML}}} measures are fitted to a power law involving the fundamental binary properties. With this, the dominant AML law for systems with orbital periods ( P ) from 0.13–1.0 day is {\dot{P}}_{{\rm{AML}}}=-1500\times 1{0}^{-12}{P}^{1.29}{M}_{{\rm{prim}}}^{2.75}{M}_{{\rm{comp}}}^{-1.00}{\dot{M}}_{-8}^{0.43} , in appropriate units. Similar AML laws for binaries below the period gap and for binaries with P > 1.0 day are derived. These three AML laws are of good accuracy and are the best representations of the actual evolution for all 77 XRBs and CVs of all classes, so the three taken together can be called “universal.”}, archive = {J_ApJ}, author = {Bradley E. Schaefer}, doi = {10.3847/1538-4357/add925}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {35}, shortjournal = {The Astrophys. J.}, title = {Evolutionary period changes for 25 X-ray binaries and the measurement of an empirical universal law for angular momentum loss in accreting binaries}, volume = {988}, year = {2025}, }
• (2025). Effective viscosity in the intracluster medium during magnetic field amplification via turbulent dynamo. ApJ, 988(1), 34. (www)

  @article{ , abstract = {Galaxy clusters, the largest gravitationally bound structures, host a hot, diffuse plasma with poorly understood viscosity and magnetic field amplification. Astrophysical plasmas are often modeled with magnetohydrodynamics (MHD), but low collision rates in environments such as the intracluster medium (ICM) hinder thermodynamic equilibrium, causing pressure anisotropies and high viscosity. High- β plasmas, dominated by thermal pressure, are prone to instabilities (e.g., firehose or mirror) that limit anisotropy, reduce viscosity, and enable small-scale dynamo-driven magnetic amplification. This study examines viscosity evolution in the ICM during turbulent magnetic field amplification. We performed 3D MHD simulations of forced turbulence with an initially weak, uniform magnetic field. Using the Chew–Goldberger–Low (CGL)-MHD framework, we incorporate anisotropic pressure dynamics and instability-driven anisotropy limitation. We analyze effective viscosity and dynamo evolution, comparing results with Braginskii-MHD and uniform-viscosity MHD. Our results show that viscosity decreases over time, allowing magnetic field amplification to saturation levels similar to nonviscous MHD. Viscosity distribution becomes bimodal, reflecting (i) collisional values and (ii) turbulence-dominated values proportional to 1 × 10 −4 L turb U turb in unstable regions. At saturation, 60% of plasma retains collisional viscosity. Braginskii-MHD reproduces similar magnetic amplification and viscosity structures. However, uniform-viscosity MHD, where viscosity equals the mean saturated CGL-MHD value, fails to capture the turbulence inertial range. These findings highlight the need for anisotropic viscosity models in studying ICM processes such as magnetic topology, cosmic ray transport, and active galactic nucleus-driven shocks. Moreover, our CGL-MHD and Braginskii-MHD models match the Coma cluster density fluctuation spectrum, reinforcing its weakly collisional nature.}, archive = {J_ApJ}, author = {S. Adduci Faria and R. Santos-Lima and E. M. de Gouveia Dal Pino}, doi = {10.3847/1538-4357/addc5f}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {34}, shortjournal = {The Astrophys. J.}, title = {Effective viscosity in the intracluster medium during magnetic field amplification via turbulent dynamo}, volume = {988}, year = {2025}, }
• (2025). Coronal magnetometry with EUV permitted lines. ApJ, 988(1), 33. (www)

  @article{ , abstract = {A major challenge in solar physics is to obtain empirical information on the magnetic field of the million-degree plasma of the solar corona. To this end, we need observables of the solar radiation sensitive to the coronal magnetic field. The most familiar observables are the polarization signals of visible and near-infrared forbidden lines of highly ionized species and some ultraviolet permitted lines, like hydrogen Ly α . While the coronal radiation in these spectral lines can only be detected for off-limb lines of sight, the coronal radiation from permitted extreme ultraviolet (EUV) lines can be observed also on the solar disk. These coronal lines are mainly collisionally excited, but it has been pointed out that some permitted EUV lines can actually be linearly polarized if their lower level carries atomic alignment, and that their linear polarization is sensitive to the orientation of the coronal magnetic field . Here we theoretically investigate the linear polarization in permitted EUV lines of a variety of ions: Fe x , Fe xi , Fe xiii , Fe xiv , Si ix , and Si x . To this end, we have developed a numerical code, which we have applied to investigate the linear polarization and magnetic sensitivity of many permitted EUV lines in a one-dimensional model of the solar corona, providing a list of the most promising lines to be further investigated for polarimetry with future space telescopes. Our next step will be to extend this work by using state-of-the-art three-dimensional coronal models.}, archive = {J_ApJ}, author = {Nataliia G. Shchukina and Javier Trujillo Bueno and Supriya Hebbur Dayananda and Rafael Manso Sainz and Andrii V. Sukhorukov}, doi = {10.3847/1538-4357/addc61}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {33}, shortjournal = {The Astrophys. J.}, title = {Coronal magnetometry with EUV permitted lines}, volume = {988}, year = {2025}, }
• (2025). Asteroseismology of WD j004917.14−252556.81, the most massive pulsating white dwarf. ApJ, 988(1), 32. (www)

  @article{ , abstract = {We present extensive follow-up time-series photometry of WD J0049−2525, the most massive pulsating white dwarf currently known, with T eff = 13,020 K and {\mathrm{log}}\,g=9.34 cm s −2 . The discovery observations detected only two significant pulsation modes. Here, we report the detection of 13 significant pulsation modes ranging from 170 to 258 s based on 11 nights of observations with the New Technology Telescope, Gemini, and Apache Point Observatory telescopes. We use these 13 modes to perform asteroseismology and find that the best-fitting models (under the assumption of an ONe core composition) have M ⋆ ≈ 1.29 M ⊙ , a surface hydrogen layer mass of {\mathrm{log}}\,({M}_{{\rm{H}}}/{M}_{\star })\lesssim -7.5 , and a crystallized core fraction of >99%. An analysis of the period spacing also strongly suggests a very high mass. The asteroseismic distance derived is in good agreement with the distance provided by Gaia. We also find tentative evidence of a rotation period of 0.3 or 0.67 days. This analysis provides the first look at the interior of a ∼1.3 M ⊙ white dwarf.}, archive = {J_ApJ}, author = {Ozcan Caliskan and Murat Uzundag and Mukremin Kilic and Francisco C. De Gerónimo and Adam Moss and Alejandro H. Córsico and Steven G. Parsons and Ingrid Pelisoli and Gracyn Jewett and Alberto Rebassa-Mansergas and Alex J. Brown and Vikram S. Dhillon and Pierre Bergeron}, doi = {10.3847/1538-4357/addc70}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {32}, shortjournal = {The Astrophys. J.}, title = {Asteroseismology of WD j004917.14−252556.81, the most massive pulsating white dwarf}, volume = {988}, year = {2025}, }
• (2025). Comparing grid model fitting methodologies for low-temperature atmospheres: Markov chain monte carlo versus random forest retrieval. ApJ, 988(1), 31. (www)

  @article{ , abstract = {The atmospheres of low-temperature stars, brown dwarfs, and exoplanets are challenging to model due to strong molecular features and complex gas and condensate chemistry. Self-consistent atmosphere models are commonly used for spectral fitting, but computational limits restrict the production of finely sampled multidimensional parameter grids, necessitating interpolation methods to infer precise parameters and uncertainties. Here, we compare two grid model fitting approaches: a Markov Chain Monte Carlo (MCMC) algorithm interpolating across spectral fluxes, and a random forest retrieval (RFR) algorithm trained on a grid model set. We test these with three low-temperature model grids—Sonora Diamondback, Sonora Elf Owl, and Spectral ANalog of Dwarfs (SAND)—and a sample of 11 L and T dwarf companions to FGKM stars with known distances, compositions, and ages. Diamondback models are optimal for early- and mid-type L dwarfs, Elf Owl for mid and late T dwarfs, and SAND for young L dwarfs and L/T transition objects. The MCMC approach yields higher fit quality and more precise parameters, though best-fit parameters are generally consistent between approaches. RFR analysis is orders of magnitude faster after training. Both approaches yield mixed results when comparing fit parameters to expected values based on the primary (metallicity and surface gravity) or evolutionary models (temperature and radius). We propose modeling low-temperature spectra efficiently by first fitting multiple model sets using RFR, followed by a more accurate MCMC assessment, to accelerate improved grid development.}, archive = {J_ApJ}, author = {Anna Lueber and Adam J. Burgasser}, doi = {10.3847/1538-4357/addd06}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {31}, shortjournal = {The Astrophys. J.}, title = {Comparing grid model fitting methodologies for low-temperature atmospheres: Markov chain monte carlo versus random forest retrieval}, volume = {988}, year = {2025}, }
• (2025). Gamma-ray burst jets in circumstellar material: Dynamics, breakout, and diversity of transients. ApJ, 988(1), 30. (www)

  @article{ , abstract = {Recent observations indicate that stripped-envelope core-collapse supernovae are often surrounded by dense circumstellar material (CSM). Motivated by this, we develop an analytic model to systematically study the dynamics of long gamma-ray burst (LGRB) jet propagation in various CSM environments. We derive a general expression for the jet head velocity ( β h ) and breakout time ( t b ) valid across Newtonian, relativistic, and intermediate regimes, accounting for a previously unrecognized dependence on 1 − β h . Our results highlight a fundamental distinction between jet propagation in massive stars, where β h ≪ 1, and in extended CSM, where 1 − β h ≪ 1. We establish an analytic success/failure criterion for jets and express it in terms of jet and CSM parameters, revealing a strong dependence on CSM radius. To quantify the relativistic nature of the jet-cocoon system, we introduce the energy-weighted proper velocity \overline{{\rm{\Gamma }}\beta } . We identify three possible jet outcomes—(a) successful jets ( \bar{{\rm{\Gamma }}\beta }\sim 10-100 ), (b) barely failed jets ( \overline{{\rm{\Gamma }}\beta }\sim 1 ), and (c) completely failed jets ( \overline{{\rm{\Gamma }}\beta }\sim 0.1 )—and constrain their respective jet/CSM parameter spaces. We show that, in (b) and (c), large CSM radii can result in luminous fast blue optical transients via cocoon cooling emission. This theoretical framework provides a basis for future observational and theoretical studies to understand the link between LGRBs, intermediate GRBs, low-luminosity LGRBs, and their environments.}, archive = {J_ApJ}, author = {Hamid Hamidani and Kunihito Ioka and Kazumi Kashiyama and Masaomi Tanaka}, doi = {10.3847/1538-4357/addd13}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {30}, shortjournal = {The Astrophys. J.}, title = {Gamma-ray burst jets in circumstellar material: Dynamics, breakout, and diversity of transients}, volume = {988}, year = {2025}, }
• (2025). Counting the unseen. II. tidal disruption event rates in nearby galaxies with REPTiDE. ApJ, 988(1), 29. (www)

  @article{ , abstract = {Tidal disruption events (TDEs) are a class of transients that occur when a star is destroyed by the tides of a massive black hole (MBH). Their rates encode valuable MBH demographic information, but this can only be extracted if accurate TDE rate predictions are available for comparisons with observed rates. In this work, we present a new, observer-friendly Python package called REPTiDE, which implements a standard loss-cone model for computing TDE rates given a stellar density distribution and an MBH mass. We apply this software to a representative sample of 91 nearby galaxies over a wide range of stellar masses with high-resolution nuclear density measurements from C. H. Hannah et al. We measure per-galaxy TDE rates ranging between 10 −7.7 and 10 −2.9 yr –1 and find that the sample-averaged rates agree well with observations. We find a turnover in the TDE rate as a function of both galaxy stellar mass and black hole mass, with the peak rates being observed in galaxies at a galaxy mass of 10 9.5 M ⊙ and a black hole mass of 10 6.5 M ⊙ . Despite the lower TDE rates inferred for intermediate-mass black holes, we find that they have gained a higher fraction of their mass through TDEs when compared to higher-mass black holes. This growth of lower-mass black holes through TDEs can enable us to place interesting constraints on their spins; we find maximum spins of a • ≈ 0.9 for black holes with masses below ∼10 5.5 M ⊙ .}, archive = {J_ApJ}, author = {Christian H. Hannah and Nicholas C. Stone and Anil C. Seth and Sjoert van Velzen}, doi = {10.3847/1538-4357/addd1b}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {29}, shortjournal = {The Astrophys. J.}, title = {Counting the unseen. II. tidal disruption event rates in nearby galaxies with REPTiDE}, volume = {988}, year = {2025}, }
• (2025). MWA and VLA observations of diffuse radio lobes in m87. ApJ, 988(1), 28. (www)

  @article{ , abstract = {This study investigates the projected, quasi-symmetric ∼46 kiloparsec-scale diffuse radio lobes surrounding the giant elliptical galaxy M87, utilizing well-sampled wideband (60 MHz–10.55 GHz) observations from the Murchison Widefield Array and Very Large Array, supplemented by data from the Low-frequency Array and Effelsberg. The observed structures feature sharp edges and filaments, with nearly uniform and moderately steep spectral indices ( α , mostly within −1.2 ≤ α ≤ −0.8), indicating turbulence. Well-sampled radio spectra for the lobes’ diffuse region are derived using the continuous injection (CI) model (with α inj ≃ −0.86 and ν b ≃ 1.72 GHz), and for its three localized regions using the impulsive injection model (e.g., the Jaffe–Perola (JP) model). From energy equipartition analysis, we estimate the typical magnetic field strength in the lobes’ diffuse region to be B eq ≃ 10 μ G. The age of the lobes is estimated as ∼30–50 Myr, based on lifetimes derived from the CI and JP models and sound crossing time. Outflow powers of ∼(0.2–2) × 10 44 erg s –1 for the lobes’ diffuse components and ∼(1–11) × 10 44 erg s –1 for the whole source are calculated. With this power assessment, we conclude that the galactic stellar wind has a negligible effect, and the active galactic nucleus (AGN)-driven jet can provide the necessary energy for the whole system. Furthermore, we argue that while the wind driven by current AGN activity is unlikely to power the lobes’ diffuse components, an average enhancement of AGN activity by a factor of ∼10 2 over the past ∼30–50 Myr remains plausible.}, archive = {J_ApJ}, author = {Linhui Wu and Fu-Guo Xie and Qian Zheng and Quan Guo and Huanyuan Shan and Dan Hu and Stefan W. Duchesne and Nick Seymour and Jingying Wang and Junhua Gu and Qingwen Wu and Zhenghao Zhu and Melanie Johnston-Hollitt and Christopher J. Riseley and Xu-Liang Fan}, doi = {10.3847/1538-4357/adddb7}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {28}, shortjournal = {The Astrophys. J.}, title = {MWA and VLA observations of diffuse radio lobes in m87}, volume = {988}, year = {2025}, }
• (2025). Exploring quasar variability with ZTF at 0 < z < 3: A universal relation with the eddington ratio. ApJ, 988(1), 27. (www)

  @article{ , abstract = {Quasars, powered by accretion onto supermassive black holes (SMBHs), exhibit significant variability, offering insights into the physics of accretion and the properties of the central engines. In this study, we analyze photometric variability and its correlation with key quasar properties, including black hole mass ( M BH ) and nuclear luminosities, using 915 quasars with 0 ≤ z < 3.0 from the All Quasar Multi-Epoch Spectroscopy sample monitored within the fifth-generation Sloan Digital Sky Survey (SDSS-V). Variability metrics were derived from approximately 6 yr light curves provided by the Zwicky Transient Facility (ZTF), while SMBH masses and luminosities were obtained from the SDSS DR16 quasar catalog of Q. Wu & Y. Shen. We identify a strong anticorrelation between variability amplitude and luminosity, which strengthens with redshift, and a redshift-dependent trend for M BH : a positive correlation at low redshifts, no significant correlation at intermediate redshifts, and an anticorrelation at the highest redshifts. Our main finding is a robust anticorrelation between photometric variability amplitude and Eddington ratio, consistent across different redshift bins. We present a general equation encapsulating this relationship, which appears to be almost free of redshift dependence, enabling predictions of quasar variability based on accretion parameters or vice versa. The derived relation with the Eddington ratio provides a unified framework for interpreting variability in active galactic nuclei and facilitates future studies of quasar variability using high-cadence surveys, such as the Vera C. Rubin Observatory’s Legacy Survey of Space and Time.}, archive = {J_ApJ}, author = {Hygor Benati Gonçalves and Swayamtrupta Panda and Thaisa Storchi Bergmann and Edward M. Cackett and Michael Eracleous}, doi = {10.3847/1538-4357/addec0}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {27}, shortjournal = {The Astrophys. J.}, title = {Exploring quasar variability with ZTF at 0 < z < 3: A universal relation with the eddington ratio}, volume = {988}, year = {2025}, }
• (2025). In search of the first stars: An ultra-compact and very-low-metallicity lyα emitter deep within the epoch of reionization. ApJ, 988(1), 26. (www)

  @article{ , abstract = {We present JWST observations of a gravitationally lensed, extremely metal-poor galaxy at redshift z = 8.203 ± 0.001 from the CANUCS survey. Based on the low oxygen to Balmer line ratios, we infer a gas-phase metallicity of 12 + log(O/H) = 6.85 (1.4% solar), making CANUCS-A370-z8-LAE one of the most metal-poor galaxies known at z > 7. The galaxy has a high H β equivalent width of 225 ± 50 Å, small half-light radius of only {r}_{\mathrm{hl}}=3{8}_{-19}^{+3} pc, and high star formation rate density of 50–100 M ⊙ yr −1 kpc −2 . The galaxy shows high-equivalent-width Ly α emission with an inferred Ly α escape fraction of 0.21 ± 0.05. The high escape fraction of Ly α is likely due to the compact starbursting nature of the galaxy combined with its location in an overdensity traced by at least two other galaxies spectroscopically confirmed to lie within δz = 0.01 that have helped to reionize the environment. The low metallicity of CANUCS-A370-z8-LAE is best explained by a model where infalling metal-poor gas dilutes the interstellar medium, rather than being a young galaxy forming its first stellar populations.}, archive = {J_ApJ}, author = {Chris J. Willott and Yoshihisa Asada and Kartheik G. Iyer and Jon Judež and Gregor Rihtaršič and Nicholas S. Martis and Ghassan T. E. Sarrouh and Guillaume Desprez and Anishya Harshan and Lamiya Mowla and Gaël Noirot and Giordano Felicioni and Maruša Bradač and Gabe Brammer and Adam Muzzin and Marcin Sawicki and Jacqueline Antwi-Danso and Vladan Markov and Roberta Tripodi}, doi = {10.3847/1538-4357/addf49}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {26}, shortjournal = {The Astrophys. J.}, title = {In search of the first stars: An ultra-compact and very-low-metallicity lyα emitter deep within the epoch of reionization}, volume = {988}, year = {2025}, }
• (2025). Changing-look active galactic nuclei: A study of Optical/UV and the highly ionized fe kα X-ray line flux variations using photoionization simulations. ApJ, 988(1), 25. (www)

  @article{ , abstract = {Significant variability in broad emission line strengths of active galactic nuclei (AGN) over months to years has been observed, often accompanied by intrinsic continuum changes. Such spectral variability challenges the traditional AGN classification scheme, which attributes differences between type 1 and type 2 to geometrical effects, as transitions between these types occur on timescales shorter than viscous ones. In this work, using the cloudy photoionization simulations, we investigated the response of the major emission line fluxes, in the optical/UV and hard X-ray bands, to changes in the intensity and shape of the continuum emission of the AGN under two scenarios: (i) changes in the X-ray power law while keeping disk emission fixed, and (ii) broadband continuum variations. We demonstrate that broad-line region (BLR) line fluxes are insensitive to X-ray power-law changes alone. Considering a well-studied case of the changing-look (CL) AGN Mrk 1018, which exhibits variations in the intrinsic disk emission, as well as the X-ray power law, our simulations reproduce observed brightening and dimming trends of the BLR emission. Moreover, we show that the highly ionized Fe K α X-ray flux, primarily produced by the H-like and He-like ions of Fe, strongly depends on the X-ray strength of the intrinsic spectral energy distribution. These findings suggest that the origin of highly ionized Fe K α emission is in the coronal part of the accretion disk and that the CL phenomenon can be triggered by intrinsic changes in the accretion properties of AGN.}, archive = {J_ApJ}, author = {Tek P. Adhikari and Santanu Mondal and Zhicheng He and Agata Rozanska and Krzysztof Hryniewicz}, doi = {10.3847/1538-4357/ade056}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {25}, shortjournal = {The Astrophys. J.}, title = {Changing-look active galactic nuclei: A study of Optical/UV and the highly ionized fe kα X-ray line flux variations using photoionization simulations}, volume = {988}, year = {2025}, }
• (2025). The onset of feedback in a1885: Evidence for large-scale quenching despite a young central active galactic nucleus. ApJ, 988(1), 24. (www)

  @article{ , abstract = {We present a new 8.5 ks Chandra observation of A1885 ( z = 0.089), obtained as part of the Cluster Evolution Reference Ensemble At Low- z (CEREAL) survey of ∼200 low- z galaxy groups and clusters. These data reveal that A1885 is a strong cool core, with a central cooling time of 0.4{3}_{-0.04}^{+0.12} Gyr, and that the central galaxy hosts an X-ray-luminous point source at its center ( L {}_{2-10\,\mathrm{keV}}\,=2.{3}_{-0.7}^{+0.9}\times 1{0}^{42} erg s −1 ), indicative of a rapidly accreting supermassive black hole (SMBH). In the context of the larger CEREAL sample, we constrain the fraction of clusters at z ∼ 0.15 with X-ray-bright ( L 2−10 > 10 42 erg s −1 ) central active galactic nuclei (AGN) to be no more than 4.1% at 95% confidence. Including radio data from LOFAR, the Giant Metrewave Radio Telescope, ASKAP, and the Very Large Array, spanning 44 MHz–150 GHz, and optical integral field unit data from the Sloan Digital Sky Survey's MaNGA, we probe the details of cooling, feeding, and feedback in this system. These data reveal that cooling of the intracluster medium is highly suppressed on large (>10 kpc) scales despite a central SMBH that is in the early stages of the self-regulation cycle (characterized by rapid accretion, physically small jets, and no large-scale low-frequency radio emission). To reconcile the large-scale quenching with a lack of visible large-scale feedback, we propose that the timescale on which energy is dissipated on large scales (>10 kpc) is significantly longer than the timescale on which black hole feeding operates on small (∼parsec) scales. This interpretation disfavors a model in which the energy is rapidly dissipated (e.g., shocks), which would synchronize the feeding and feedback timescales, and favors a model in which the heating effects of AGN feedback can linger long after the outburst has passed (e.g., turbulent mixing).}, archive = {J_ApJ}, author = {Laurel White and Michael McDonald and Francesco Ubertosi and Massimo Gaspari and Julie Hlavacek-Larrondo and Helen Russell and Taweewat Somboonpanyakul}, doi = {10.3847/1538-4357/ade14b}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {24}, shortjournal = {The Astrophys. J.}, title = {The onset of feedback in a1885: Evidence for large-scale quenching despite a young central active galactic nucleus}, volume = {988}, year = {2025}, }
• (2025). BatAnalysis—A comprehensive python pipeline for swift BAT time-tagged event data analysis. ApJ, 988(1), 23. (www)

  @article{ , abstract = {The Neil Gehrels Swift Observatory (Swift) Burst Alert Telescope (BAT) is a coded aperture gamma-ray instrument with a large field of view that was designed to detect and localize transient events. When a transient is detected, either on board or externally, the BAT saves time-tagged event (TTE) data, which provide the highest-quality information of the locations of the photons on the detector plane and their energies. These data can be used to produce spectra, lightcurves, and sky images of a transient event. While these data products are produced by the Swift Data Center and can be produced by current software, they are often preset to certain time and energy intervals, which have limited their use in the current time domain and multimessenger environment. Here, we introduce a new capability for the BatAnalysis Python package to download and process TTE data under an open-source Python framework that allows for easy interfacing with other Python packages. The new capabilities of the BatAnalysis software allow for TTE data to be used by the community in a variety of advanced customized analyses of astrophysical sources which BAT may have TTE data for, such as fast radio bursts (FRBs), gamma-ray bursts (GRBs), low-mass X-ray binaries (LMXB), soft gamma repeaters, magnetars, and many other sources. We highlight the usefulness of the BatAnalysis package in analyzing TTE data produced by an onboard GRB trigger, an FRB external trigger, a subthreshold detection of the LMXB EXO 0748–676, and an external trigger of a GRB that BAT detected during a slew.}, archive = {J_ApJ}, author = {Tyler Parsotan and David M. Palmer and Samuele Ronchini and James Delaunay and Aaron Tohuvavohu and Sibasish Laha and Amy Lien and S. Bradley Cenko and Hans Krimm and Craig Markwardt}, doi = {10.3847/1538-4357/ade240}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {23}, shortjournal = {The Astrophys. J.}, title = {BatAnalysis—A comprehensive python pipeline for swift BAT time-tagged event data analysis}, volume = {988}, year = {2025}, }
• (2025). Correlation between U/Th and Pb/Os abundance ratios and its application in nuclear cosmochronology. ApJ, 988(1), 22. (www)

  @article{ , abstract = {The abundance ratios of radioactive elements U/Th and stable elements Pb/Os from the r -process are found to have a strong correlation. This correlation is quite robust with respect to astrophysical conditions. The U/Th–Pb/Os correlation is applied to provide customized initial abundance ratios U/Th from the observed abundance ratios Pb/Os for six r -process enhanced metal-poor stars. The ages of these six metal-poor stars are predicted by the U/Th chronometer, which are approximately between 11 and 15 Gyr. Their ages are compatible with the cosmic age of 13.8 billion years predicted from the cosmic microwave background radiation.}, archive = {J_ApJ}, author = {Y. Y. Huang and Q. Q. Cui and X. H. Wu and S. Q. Zhang}, doi = {10.3847/1538-4357/ade390}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {22}, shortjournal = {The Astrophys. J.}, title = {Correlation between U/Th and Pb/Os abundance ratios and its application in nuclear cosmochronology}, volume = {988}, year = {2025}, }
• (2025). Searching for radio pulsars in old open clusters from the parkes archive. ApJ, 988(1), 21. (www)

  @article{ , abstract = {Motivated by the discovery of a pulsar in the direction of the old open cluster NGC 6791, we conducted a search for radio pulsars in archival Parkes observations targeting similar old open clusters. We reprocessed 224 observations totalling 75.02 hr from four clusters: Theia 1661, NGC 6259, Pismis 3, and Trumpler 20. Our analysis identified five known pulsars and three new rotating radio transient (RRAT) candidates. By comparing the measured dispersion measures (DMs) with the expected DM values for each cluster derived from YMW16 and NE2001 models, we conclude that most detected sources are likely background pulsars. However, RRAT J1749−25 in Theia 1661 and RRAT J1237−60 in Trumpler 20 have DMs reasonably close to their respective clusters, suggesting possible membership. The association between PSR J1750−2536 and Theia 1661 remains ambiguous due to its intermediate DM. These candidate cluster-associated neutron stars warrant follow-up with more sensitive telescopes such as MeerKAT or the Square Kilometre Array, potentially offering valuable insights into neutron star retention mechanisms and evolution in open cluster environments.}, archive = {J_ApJ}, author = {S. B. Zhang and J. J. Wei and X. Yang and S. Dai and J. S. Wang and L. Toomey and S. Q. Wang and G. Hobbs and X. F. Wu and L. Staveley-Smith}, doi = {10.3847/1538-4357/ade802}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {21}, shortjournal = {The Astrophys. J.}, title = {Searching for radio pulsars in old open clusters from the parkes archive}, volume = {988}, year = {2025}, }
• (2025). Convection anisotropies of cosmic rays in highly magnetized plasma. ApJ, 988(1), 20. (www)

  @article{ , abstract = {Recently, Y. Zhang & S. Liu proposed a turbulent convection model for multiscale anisotropies of cosmic rays (CRs), with an assumption of isotropic diffusion such that the anisotropies are statistically isotropic. However, this assumption may be unrealistic for TeV CRs, whose observations have revealed the significance of the local interstellar background magnetic field. To meet the difficulty, the turbulent convection scenario needs to be extended to cover anisotropic diffusion. In this paper, we focus on the parallel diffusion with isotropic pitch-angle scattering, which may be an approximation to the transport process driven by weak hydromagnetic waves in a magnetic flux tube, where fluctuations of the wave velocities lead to the turbulent convection. The consequence is the breaking of the statistical isotropy, while the overall shape of the angular power spectrum, \overline{{C}_{\ell }}\propto {\ell }^{-\gamma -1} ( ℓ ≫ 1), remains similar to that in the isotropic diffusion model, where ℓ is degrees of spherical harmonics and γ is the turbulence spectral index of the convection field. It is then expected that the power-law index of the TeV CR small-scale angular power spectrum can be explained with the Kolmogorov law γ = 5/3, irrespective of the background magnetic field to some extent.}, archive = {J_ApJ}, author = {Yiran Zhang and Siming Liu}, doi = {10.3847/1538-4357/ade2d5}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {20}, shortjournal = {The Astrophys. J.}, title = {Convection anisotropies of cosmic rays in highly magnetized plasma}, volume = {988}, year = {2025}, }
• (2025). Detection of [O iii]88 μm in JADES-GS-z14-0 at z = 14.1793. ApJ, 988(1), 19. (www)

  @article{ , abstract = {We report the first successful Atacama Large Millimeter/submillimeter Array (ALMA) follow-up observations of a secure z > 10 JWST-selected galaxy, by robustly detecting (6.6 σ ) the [O iii ] 88 μ m line in JADES-GS-z14-0 (hereafter GS-z14). The ALMA detection yields a spectroscopic redshift of z = 14.1793 ± 0.0007, and increases the precision on the prior redshift measurement of z=14.3{2}_{-0.20}^{+0.08} from NIRSpec by ≳180×. Moreover, the redshift is consistent with that previously determined from a tentative detection (3.6 σ ) of C iii ] 1907,1909 ( z = 14.178 ± 0.013), solidifying the redshift determination via multiple line detections. We measure a line luminosity of L [O iii ]88 = (2.1 ± 0.5) × 10 8 L ⊙ , placing GS-z14 at the lower end, but within the scatter of, the local L [O iii ]88 –star formation rate relation. No dust continuum from GS-z14 is detected, suggesting an upper limit on the dust-to-stellar mass ratio of <2 × 10 −3 , consistent with dust production from supernovae with a yield y d < 0.3 M ⊙ . Combining a previous JWST/MIRI photometric measurement of the [O iii ] λλ 4959,5007 Å and H β lines with Cloudy models, we find GS-z14 to be surprisingly metal-enriched ( Z ∼ 0.05–0.2 Z ⊙ ) a mere 300 Myr after the Big Bang. The detection of a bright oxygen line in GS-z14 thus reinforces the notion that galaxies in the early Universe undergo rapid evolution.}, archive = {J_ApJ}, author = {Sander Schouws and Rychard J. Bouwens and Katherine Ormerod and Renske Smit and Hiddo Algera and Laura Sommovigo and Jacqueline Hodge and Andrea Ferrara and Pascal A. Oesch and Lucie E. Rowland and Ivana van Leeuwen and Mauro Stefanon and Thomas Herard-Demanche and Yoshinobu Fudamoto and Huub Röttgering and Paul van der Werf}, doi = {10.3847/1538-4357/adbf1b}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {19}, shortjournal = {The Astrophys. J.}, title = {Detection of [O iii]88 μm in JADES-GS-z14-0 at z = 14.1793}, volume = {988}, year = {2025}, }
• (2025). 3D magnetohydrodynamic wave propagation and energy transport in a simulated solar vortex. ApJ, 988(1), 18. (www)

  @article{ , abstract = {Magnetic flux tubes in the presence of background rotational flows are abundant throughout the solar atmosphere and may act as conduits for MHD waves to transport energy throughout the solar atmosphere. Here we investigate the contribution from MHD waves to the Poynting flux in a 3D numerical simulation of a realistic solar atmosphere, modeling a structure resembling a solar vortex tube, using the PLUTO code in the presence of different plasma flow configurations. These simulations feature a closed magnetic loop system where a rotational flow is imposed at one footpoint in addition to photospheric perturbations acting as a wave driver mimicking those of p -modes. We find that a variety of MHD waves exist within the vortex tube, including sausage, kink, and torsional Alfvén waves, owing to the photospheric wave driver and the nature of the rotational flow itself. We demonstrate how the visual interpretation of different MHD modes becomes nontrivial when a background rotational flow is present compared to a static flux tube. By conducting a simulation both with and without the rotational plasma flow, we demonstrate how the perturbed Poynting flux increases in the presence of the rotational flow as the waves transport increased magnetic energy. We attribute this increase to the dynamical pressure from the rotational flow increasing the plasma density at the tube boundary, which acts to trap the wave energy more effectively inside the vortex. Moreover, we demonstrate how the Poynting flux is always directed upward in weakly twisted magnetic flux tubes.}, archive = {J_ApJ}, author = {Samuel J. Skirvin and Viktor Fedun and Gary Verth and Istvan Ballai}, doi = {10.3847/1538-4357/adce73}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {18}, shortjournal = {The Astrophys. J.}, title = {3D magnetohydrodynamic wave propagation and energy transport in a simulated solar vortex}, volume = {988}, year = {2025}, }
• (2025). Low accretion rates in black holes in late-stage merger ultraluminous infrared galaxies. ApJ, 988(1), 17. (www)

  @article{ , abstract = {We explore the accretion rates of supermassive black holes (SMBHs) in late-stage galaxy mergers by observing three ultraluminous infrared galaxies (ULIRGs), IRAS 14378-3651, IRAS 17208-0014 and IRAS 23365+3604, using the JWST/MIRI Medium Resolution Spectrometer and JWST/NIRSpec integral field unit. In all three cases, we fail to detect [Ne vi ] λ 7.65 μ m, a robust active galactic nuclei (AGN) tracer lying in a low-opacity interstellar window, nor do we detect any other lines that might indicate AGNs. The only detected high-excitation emission line, [Mg iv ] ( λ 4.488 μ m), arises from shocks associated with supernovae. Our new, deep flux limits on AGN tracers in the near- and mid-infrared indicate that the nuclear obscuration of any purported AGNs in our sample is isotropic, i.e., the far-infrared luminosities of these galaxies are unlikely to be driven by escaping AGN power. This allows us to show that the Eddington ratios of their SMBHs are low. We then assemble an unbiased sample of 19 ULIRGs (from the IRAS Bright Galaxy Sample with L (TIR) ≥ 10 12 L ⊙ ) in late-stage mergers and show that their dynamically measured black hole masses are consistent with the values from scaling from their stellar masses. On this basis, we show that the Eddington ratios of any AGNs in 15 of these galaxies are also very low, ≲10%. This indicates that any black holes are in a relatively quiescent state. That is, high levels of accretion are found in only a minority of late-merger-phase ULIRGs.}, archive = {J_ApJ}, author = {George H. Rieke and Victorine A. Buiten and Charles E. Goldberg and Jane Morrison and Paul van der Werf and Almudena Alonso-Herrero and Stacey Alberts and Nina Bonaventura and Zhiyuan Ji and Jianwei Lyu and P. Rinaldi and Meredith A. Stone and Yang Sun and Yongda Zhu}, doi = {10.3847/1538-4357/add2fd}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {17}, shortjournal = {The Astrophys. J.}, title = {Low accretion rates in black holes in late-stage merger ultraluminous infrared galaxies}, volume = {988}, year = {2025}, }
• (2025). On the extended soft X-ray and fe kα emission in NGC 1068. ApJ, 988(1), 16. (www)

  @article{ , abstract = {The soft X-ray excess and Fe K α emission lines are widely observed in Seyfert galaxies, with their origin still in debate. We present a detailed spatially resolved image and spectral analysis of the Seyfert 2 galaxy NGC 1068 using high-resolution Chandra ACIS data. We find that the soft X-ray emission and iron emission show extended structures in the northeast and southwest directions. Especially, the soft X-ray extends predominantly in the 1 ″ −15 ″ (∼72 pc–1 kpc) northeast sector with a distance of at least ∼10 ″ (∼700 pc), and its 0.5–3.0 keV flux is about ∼2/3 of that from the 1 ″ radius circular region centered on the core of NGC 1068. We fit the soft X-ray spectra from the core and two bright blobs (∼3 ″ , S1 and ∼1 \mathop{.}\limits^{\unicode{x02033}} 5, S2 from the nucleus) as a dual-temperature plasma with two APEC models. Our analysis suggests that the extended soft X-ray emission in NGC 1068, as well as contributions to Fe K α emission from the extended region, likely originate from the interactions between the jet and the interstellar medium, offering further insights into the origin of soft X-ray excess and Fe K α emission lines in similar Seyfert sources. However, extended X-ray emission outside the ionization cone might be influenced by additional processes; future multiwavelength observations will be needed to test these possibilities.}, archive = {J_ApJ}, author = {Songbo Gao and Hongxing Yin and Shaoming Hu}, doi = {10.3847/1538-4357/adddb0}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {16}, shortjournal = {The Astrophys. J.}, title = {On the extended soft X-ray and fe kα emission in NGC 1068}, volume = {988}, year = {2025}, }
• (2025). Formation and evolution of compact binaries containing intermediate-mass black holes in dense star clusters. ApJ, 988(1), 15. (www)

  @article{ , abstract = {We investigate the evolution of star clusters containing intermediate-mass black holes (IMBHs) of 300–5000 M ⊙ , focusing on the formation and evolution of IMBH–stellar-mass black hole (M BH ≲ 10 2 M ⊙ ) binaries. Dense stellar systems like globular clusters (GCs) or nuclear star clusters offer unique laboratories for studying the existence and impacts of IMBHs. IMBHs residing in GCs have been under speculation for decades, with their broad astrophysical implications for the cluster’s dynamical evolution, stellar population, and gravitational-wave (GW) signatures, among others. While existing GW observatories, such as the Advanced Laser Interferometer Gravitational-wave Observatory (aLIGO), target binaries with relatively modest mass ratios, q ≲ 10, future observatories, such as the Einstein Telescope (ET) and the Laser Interferometer Space Antenna (LISA), will detect intermediate-mass ratio inspirals (IMRIs) with q > 10. This work explores the potential for detecting IMRIs by adopting these upcoming telescopes. For our experiments, we perform multiple direct N -body simulations with IMBHs, utilizing Nbody6++GPU , after implementing the GW merger schemes for IMBHs. We then study the statistical properties of the resulting IMRIs, such as the event rates and orbital properties. Assuming that IMRIs with a signal-to-noise ratio ​​> 8 are detectable, we derive the following detection rates for each observatory: ≲0.02 yr −1 for aLIGO, ∼101−355 yr −1 for ET, ∼186−200 yr −1 for LISA, ∼0.24−0.34 yr −1 for aSOGRO, and ∼3880−4890 yr −1 for DECIGO. Our result confirms the capability of detecting IMRIs with future GW telescopes.}, archive = {J_ApJ}, author = {Seungjae Lee and Hyung Mok Lee and Ji-hoon Kim and Rainer Spurzem and Jongsuk Hong and Eunwoo Chung}, doi = {10.3847/1538-4357/adde52}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {15}, shortjournal = {The Astrophys. J.}, title = {Formation and evolution of compact binaries containing intermediate-mass black holes in dense star clusters}, volume = {988}, year = {2025}, }
• (2025). Two events with spectacular moving structures in a failed solar filament eruption. ApJ, 988(1), 14. (www)

  @article{ , abstract = {We investigate the complex magnetic reconnection process between the filament and surrounding loops during the failed filament eruption that occurred in NOAA active region 13445 on 2023 September 24, using extreme-ultraviolet observations from the Solar Dynamics Observatory and high-resolution H α imaging from the New Vacuum Solar Telescope. This failed filament eruption is associated with an M4.4 flare (SOL2023-09-24T03:28). At the early phase of the filament eruption, the filament displays a distinct clockwise rotational motion, suggesting an untwisting motion. During the flare precursor phase, the northwest slipping motion of the brightenings at the filament’s left footpoint, along with the brightening and continuous expansion of the nearby loops at the northwest, suggest the occurrence of a slipping magnetic reconnection between the filament and peripheral loops at the quasi-separatrix layer. After the slipping motion begins, significant brightenings of filament materials and multiple bright structures moving toward the two filament footpoints are observed during the two episodes of magnetic reconnection between the filament and the overlying loops, with the most prominent brightenings and the moving structures occurring during the main phase of the M4.4 flare. The observed untwisting motion of the filament and the twist reduction derived from the nonlinear force-free field extrapolation suggest that the magnetic reconnection between the filament and the peripheral and overlying loops plays a significant role in the failure of the filament eruption by greatly reducing its twist.}, archive = {J_ApJ}, author = {Yudi Ou and Yingna Su and Qingmin Zhang and Haisheng Ji and Leping Li and Hongqiang Song and Yijun Hou and Guiping Zhou and Baolin Tan and Kaifan Ji and Zhe Xu and Yongyuan Xiang and Zhenyong Hou and Yang Guo and Ye Qiu}, doi = {10.3847/1538-4357/addec9}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {14}, shortjournal = {The Astrophys. J.}, title = {Two events with spectacular moving structures in a failed solar filament eruption}, volume = {988}, year = {2025}, }
• (2025). Insight into the origin of multiwavelength emissions of PKS 1510−089 through modeling 12 SEDs from 2008 to 2015. ApJ, 988(1), 13. (www)

  @article{ , abstract = {PKS 1510−089 is one of the most peculiar sources among the flat spectrum radio quasars, exhibiting a notable big blue bump. This provides a unique opportunity to explore the coupling between the activity of the central engine and the relativistic jet, offering further insight into the origin of the multiwavelength emissions. To this end, we collected multiwavelength data spanning four periods from 2008 to 2015 and performed the spectral energy distribution (SED) modeling using a one-zone homogeneous leptonic model. In the model, a multichromatic accretion disk (AD) is used to fit the optical/UV data sets, while the external radiation fields from the broad-line region (BLR) and dusty torus (DT) are properly considered to produce the high-energy γ -ray emissions. Our best fit to 12 SEDs yields the following results: (i) The innermost stable orbit ( R ISO ) of the AD is not stable but varies between 3 R S and 18 R S during these observations. (ii) The high-energy hump of the SED is well dominated by Compton scattering of the BLR photons, while the X-ray flux may be comprised of multiple radiation components. (iii) The γ -ray emitting regions are generally matter-dominated, with low magnetization, and are located beyond the BLR but within the DT. At such distance, the multiwavelength emissions are likely to originate from shock accelerations. (iv) For the energization of the relativistic jet, our study supports the Blandford−Znajek mechanism, instead of the Blandford−Payne mechanism, as the latter fails to power the jet.}, archive = {J_ApJ}, author = {Maichang Lei and Yuan Zheng and Jianfu Zhang and Yuhai Yuan and Jiancheng Wang}, doi = {10.3847/1538-4357/addf3d}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {13}, shortjournal = {The Astrophys. J.}, title = {Insight into the origin of multiwavelength emissions of PKS 1510−089 through modeling 12 SEDs from 2008 to 2015}, volume = {988}, year = {2025}, }
• (2025). Observation of diffuse galactic light near the galactic center with ONC-T on board hayabusa2. ApJ, 988(1), 12. (www)

  @article{ , abstract = {Diffuse Galactic light (DGL) is starlight scattered by interstellar dust. In visible wavelengths, earlier studies observed DGL toward regions of low optical depth in high Galactic latitude, and show marginal consistency with a theoretical model assuming single scattering by dust grains. However, a model for DGL in regions of high optical depth has not been established. In this study, we analyze wide-field imaging data toward a region of high optical depth near the Galactic center, which was obtained with the Optical Navigation Camera on board the Hayabusa2 spacecraft. The data are reduced by dark-current and stray-light subtraction, flat-field correction, and sensitivity calibration for the DGL measurement. In the image, we select dark low-intensity areas where background starlight is highly absorbed by interstellar dust, and extract the DGL component by masking pixels contaminated by stars. As a result, we find that the DGL intensity decreases toward high optical depth, and this trend is reversed from the previous measurements in optically thin regions. To explain the observed trend, we introduce DGL models inferred from a radiative transfer equation in a plane-parallel dusty slab. By assuming literature values for the albedo and scattering asymmetry factor of interstellar dust, the measured DGL intensity can be fitted by a model in which a dust slab without internal emitters is illuminated by backside stars.}, archive = {J_ApJ}, author = {Kei Sano and Yuto Tome and Kana Kurosaki and Kohji Tsumura and Shuji Matsuura and Kohji Takimoto and Takahiro Iwata and Manabu Yamada and Tomokatsu Morota and Toru Kouyama and Masahiko Hayakawa and Yasuhiro Yokota and Eri Tatsumi and Moe Matsuoka and Naoya Sakatani and Koki Yumoto and Shingo Kameda and Hidehiko Suzuki and Yuichiro Cho and Kazuo Yoshioka and Kazunori Ogawa and Kei Shirai and Hirotaka Sawada and Seiji Sugita}, doi = {10.3847/1538-4357/addfd3}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {12}, shortjournal = {The Astrophys. J.}, title = {Observation of diffuse galactic light near the galactic center with ONC-T on board hayabusa2}, volume = {988}, year = {2025}, }
• (2025). FAST observation of polarized radio emission of rotating radio transient j2325−0530. ApJ, 988(1), 11. (www)

  @article{ , abstract = {In this study, we present a detailed analysis of single-pulse emission from the rotating radio transient (RRAT) J2325−0530, observed at 1250 MHz using the Five-hundred-meter Aperture Spherical Radio Telescope. A total of 168 burst pulses were detected within 0.8 hr of observation, yielding a detection rate 3 to 4 times higher than those previously reported. For the first time in this RRAT, we detected sequences of consecutive single-pulse emission lasting two to six spin periods. The single pulses exhibit significant variability in linear polarization, circular polarization, and polarization position angle, while the average profile displays weak polarization and a complex position angle structure. The distributions of fluence and waiting time, together with the significant correlation between fluence and pulse width, indicate that the emission behavior of RRAT J2325−0530 resembles that of giant pulse phenomena. We also measured the scintillation bandwidth and timescale at 1250 MHz to be 3.45 ± 0.07 MHz and 16.67 ± 0.35 minutes, respectively. In three single pulses, we detected quasiperiodic microstructure in the Stokes I , L , and V parameters, with differing microstructure periods across these components. Nevertheless, the observed microstructure periods follow the known linear relationship with the pulsar rotation period. These results support the view that RRATs share the same underlying emission physics of normal pulsars, while also revealing additional complexity in the origin of microstructure.}, archive = {J_ApJ}, author = {Shi-jun Dang and Zi-wei Wu and Ji-guang Lu and Peng Jiang and Wei Li and Yu-lan Liu and Yan-qing Cai and Jian-ping Yuan and Na Wang}, doi = {10.3847/1538-4357/ade23a}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {11}, shortjournal = {The Astrophys. J.}, title = {FAST observation of polarized radio emission of rotating radio transient j2325−0530}, volume = {988}, year = {2025}, }
• (2025). Expectation for the hard X-ray and gamma-ray emission from pair-instability supernovae. ApJ, 988(1), 10. (www)

  @article{ , abstract = {Pair-instability supernovae (PISNe) are predicted thermonuclear explosions of massive stars with helium core masses exceeding ∼65 M ⊙ , and they synthesize substantial amounts of radioactive 56 Ni ( M ( 56 Ni) ∼ 60 M ⊙ in extreme cases). To investigate their observational signatures, we developed a multi-D Monte Carlo radiation transport code, assuming spherical symmetry in the background medium and the photon sources distribution, and performed simulations of gamma-ray and hard X-ray emissions from the decay chain 56 Ni→ 56 Co→ 56 Fe. We find that key gamma-ray lines (847 and 1238 keV) from 56 Co decay in the 130 M ⊙ helium core model can be detected up to 300–400 Mpc by next-generation MeV gamma-ray telescopes. In contrast, the signals from the 100 M ⊙ model remain below the detection limits. Our results provide the template for gamma-ray follow-up observations of PISNe. Considering theoretical predictions and observational constraints, we estimate PISN event rates within 300 Mpc to be approximately 0.01–0.1 events per year, highlighting their rarity but also emphasizing their feasibility as targets for future gamma-ray observations over the decade.}, archive = {J_ApJ}, author = {Ryo Sawada}, doi = {10.3847/1538-4357/ade3cd}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {10}, shortjournal = {The Astrophys. J.}, title = {Expectation for the hard X-ray and gamma-ray emission from pair-instability supernovae}, volume = {988}, year = {2025}, }
• (2025). Application of deep learning to the classification of stokes profiles: From the quiet sun to sunspots. ApJ, 988(1), 9. (www)

  @article{ , abstract = {The morphology of circular polarization profiles from solar spectropolarimetric observations encodes information about the magnetic field strength, inclination, and line-of-sight velocity gradients. Previous studies used manual methods or unsupervised machine learning (ML) to classify the shapes of circular polarization profiles. We trained a multilayer perceptron comparing classifications with unsupervised ML. The method was tested on quiet Sun data sets from Daniel K. Inouye Solar Telescope (DKIST), Hinode, and GREGOR, as well as simulations of granulation and a sunspot. We achieve validation metrics typically close to or above 90%. We also present the first statistical analysis of quiet Sun DKIST/ViSP data using inversions and our supervised classifier. We demonstrate that classifications with unsupervised ML alone can introduce systemic errors that could compromise statistical comparisons. DKIST and Hinode classifications in the quiet Sun are similar, despite our modeling indicating spatial resolution differences should alter the shapes of circular polarization signals. Asymmetrical (symmetrical) profiles are less (more) common in GREGOR than DKIST or Hinode data, consistent with narrower response functions in the 1564.85 nm line. Single-lobed profiles are extremely rare in GREGOR data. In the sunspot simulation, the 630.25 nm line produces “double” profiles in the penumbra, likely a manifestation of magneto-optical effects in horizontal fields; these are rarer in the 1564.85 nm line. We find the 1564.85 nm line detects more reverse polarity magnetic fields in the penumbra, in contradiction to observations. We detect mixed-polarity profiles in nearly one fifth of the penumbra. Supervised ML robustly classifies solar spectropolarimetric data, enabling detailed statistical analyses of magnetic fields.}, archive = {J_ApJ}, author = {Ryan J. Campbell and M. Mathioudakis and Carlos Quintero Noda and P. H. Keys and D. Orozco Suárez}, doi = {10.3847/1538-4357/addb49}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {9}, shortjournal = {The Astrophys. J.}, title = {Application of deep learning to the classification of stokes profiles: From the quiet sun to sunspots}, volume = {988}, year = {2025}, }
• (2025). The milky way radial metallicity gradient as an equilibrium phenomenon: Why old stars are metal rich. ApJ, 988(1), 8. (www)

  @article{ , abstract = {Metallicities of both gas and stars decline toward large radii in spiral galaxies, a trend known as the radial metallicity gradient. We quantify the evolution of the metallicity gradient in the Milky Way as traced by APOGEE red giants with age estimates from machine learning algorithms. Stars up to ages of ∼9 Gyr follow a similar relation between metallicity and Galactocentric radius. This constancy challenges current models of Galactic chemical evolution, which typically predict lower metallicities for older stellar populations. Our results favor an equilibrium scenario , in which the gas-phase gradient reaches a nearly constant normalization early in the disk lifetime. Using a fiducial choice of parameters, we demonstrate that one possible origin of this behavior is an outflow that more readily ejects gas from the interstellar medium (ISM) with increasing Galactocentric radius. A direct effect of the outflow is that baryons do not remain in the ISM for long, which causes the ratio of star formation to accretion, {\dot{{\rm{\Sigma }}}}_{\star }/{\dot{{\rm{\Sigma }}}}_{\,\rm{in}\,} , to quickly become constant. This ratio is closely related to the local equilibrium metallicity, since its numerator and denominator set the rates of metal production by stars and hydrogen gained through accretion, respectively. Building in a merger event results in a perturbation that evolves back toward the equilibrium state on ∼Gyr timescales. Under the equilibrium scenario, the radial metallicity gradient is not a consequence of the inside-out growth of the disk but instead reflects a trend of declining {\dot{{\rm{\Sigma }}}}_{\star }/{\dot{{\rm{\Sigma }}}}_{\,\rm{in}\,} with increasing Galactocentric radius.}, archive = {J_ApJ}, author = {James W. Johnson and David H. Weinberg and Guillermo A. Blanc and Ana Bonaca and Gwen C. Rudie and Yuxi (Lucy) Lu and Bronwyn Reichardt Chu and Emily J. Griffith and Tawny Sit and Jennifer A. Johnson and Liam O. Dubay and Miqaela K. Weller and Daniel A. Boyea and Jonathan C. Bird}, doi = {10.3847/1538-4357/addbe5}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {8}, shortjournal = {The Astrophys. J.}, title = {The milky way radial metallicity gradient as an equilibrium phenomenon: Why old stars are metal rich}, volume = {988}, year = {2025}, }
• (2025). On the origin of jupiter’s fuzzy core: Constraints from N-body, impact, and evolution simulations. ApJ, 988(1), 7. (www)

  @article{ , abstract = {It has been suggested that Jupiter’s fuzzy core could be a result of a giant impact. Here, we investigate the expected impact conditions from N -body simulations. We then use state-of-the-art smoothed particle hydrodynamics simulations to investigate the results of impacts with different conditions including various impactor masses and composition, different formation stages in Jupiter’s growth, and different resolutions. We next simulate the long-term thermal evolution of Jupiter postimpact. We find that 3D N -body simulations predict rather oblique impacts, and that head-on collisions are rare. Moreover, our results show that, even under a head-on collision, Jupiter’s fuzzy core cannot be formed. We next simulated Jupiter’s thermal evolution and showed that, unless postimpact temperatures are extremely low, a giant impact would not lead to an extended dilute core as inferred by interior models. We conclude that Jupiter’s fuzzy core is not caused by an impact and is likely to be an outcome of its formation process.}, archive = {J_ApJ}, author = {Thomas Meier and Christian Reinhardt and Sho Shibata and Simon Müller and Joachim Stadel and Ravit Helled}, doi = {10.3847/1538-4357/addbe6}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {7}, shortjournal = {The Astrophys. J.}, title = {On the origin of jupiter’s fuzzy core: Constraints from N-body, impact, and evolution simulations}, volume = {988}, year = {2025}, }
• (2025). Effect of magnetic field on the accretion phase of population III star formation. ApJ, 988(1), 6. (www)

  @article{ , abstract = {We examine the impact of the magnetic field on Population III star formation by varying its strength. We perform simulations with magnetic field strengths ranging from 10 −20 G to 10 −4 G, in addition to a model without a magnetic field. The simulations are run for >1000–1400 yr after the first protostar forms. In weak-field models, the surrounding disk fragments, forming multiple protostars, and the magnetic field is amplified by the orbital motion and rotation of these protostars. In the model without a magnetic field, frequent fragmentation occurs, and the most massive protostar reaches ∼200 M ⊙ . However, in models with a magnetic field, once the magnetic field is amplified, the protostars merge to form a single massive protostar, and no further fragmentation occurs except in the model with the strongest magnetic field. Even after the formation of the single protostar, the magnetic field continues to amplify, leading to the formation of a thick disk supported by magnetic pressure and a global spiral pattern. In models with moderate or strong magnetic fields, a rotating disk can form, but fragmentation does not occur, and a strong magnetic field drives an outflow. However, the range of parameters for both disk formation and outflow driving is very narrow, making their appearance under realistic conditions unlikely. Given the weak magnetic field in the early Universe, Population III stars are expected to form as single stars, surrounded by a thick disk with a spiral pattern. Thus, the magnetic field, regardless of its strength, plays a crucial role in Population III star formation.}, archive = {J_ApJ}, author = {Masahiro N. Machida and Shingo Hirano and Shantanu Basu}, doi = {10.3847/1538-4357/addc56}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {6}, shortjournal = {The Astrophys. J.}, title = {Effect of magnetic field on the accretion phase of population III star formation}, volume = {988}, year = {2025}, }
• (2025). The dust extinction curve: Beyond R(V). ApJ, 988(1), 5. (www)

  @article{ , abstract = {The dust extinction curve is typically parameterized by a single variable, R ( V ), in optical and near-infrared wavelengths. R ( V ) controls the slope of the extinction-versus-wavelength curve, and is thought to reflect the grain-size distribution and composition of dust. Low-resolution, flux-calibrated BP/RP spectra from Gaia have allowed the determination of the extinction curve along sightlines to 130 million stars in the Milky Way and Magellanic Clouds. We show that these extinction curves contain more than a single degree of freedom—that is, that they are not simply described by R ( V ). We identify a number of components that are orthogonal to R ( V ) variation, and we show that these components vary across the sky in coherent patterns that resemble interstellar medium (ISM) structure. These components encode variation in the 770 nm extinction feature, intermediate-scale and very broad structure, and a newly identified feature at 850 nm, and they likely trace both dust composition and local conditions in the ISM. Correlations of the 770 and 850 nm features with R ( V ) suggest that their carriers become more abundant as the carrier of the 2175 Å feature is destroyed. Our 24 million extinction-curve decompositions and feature equivalent-width measurements are publicly available at doi:10.5281/zenodo.14005028.}, archive = {J_ApJ}, author = {Gregory M. Green and Xiangyu Zhang and Ruoyi Zhang}, doi = {10.3847/1538-4357/addd11}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {5}, shortjournal = {The Astrophys. J.}, title = {The dust extinction curve: Beyond R(V)}, volume = {988}, year = {2025}, }
• (2025). Local analogs of potential ionizers of the intergalactic medium: Compact star-forming galaxies with intense c IV λ1550 emission. ApJ, 988(1), 4. (www)

  @article{ , abstract = {We performed spectroscopic analyses of five local compact star-forming galaxies (CSFGs) with extremely high [O iii ]/[O ii ] (O 32 ) ratios (>20). These targets remarkably share similar properties with high-redshift C iv emitters at z > 6: high H β equivalent widths (EWs > 200Å), extreme O 32 ratios, low metallicities (12+log(O/H) ≲ 7.8), low C/O abundances (log(C/O) < −0.7), and high ionization conditions (log U > −2). The ultraviolet (UV) spectra were acquired using the Hubble Space Telescope’s (HST) Cosmic Origins Spectrograph and Space Telescope Imaging Spectrograph. We have identified a wealth of rest-frame UV emission lines (C iv , He ii , O iii ], C iii ]) in the HST spectra. Notably, all our targets show intense C iv emission lines with rest-frame EWs > 10 Å, indicative of hard ionizing radiation. The rest-frame UV emission line diagnostics disfavor an active galactic nucelus and could be consistent with significant shock contributions to the source of ionizing radiation. Four of our targets show high C iv /C iii ] ratios (≥1.4), suggestive of strong Lyman-continuum leakage (LyC escape fraction, f esc,LyC > 10%) from these sources. This is consistent with their Ly α -inferred LyC escape fractions ( f esc,LyC = 9%–31%). We derive relative C/O abundances from our sources, showing log(C/O) values from −1.28 to −0.77, comparable to those of reionization-era galaxies at z ≳ 6. The properties of the CSFGs, particularly their intense C iv emission and high O 32 ratios, which suggest significant LyC escape fractions, are similar to those of the reionization-era C iv emitters. These similarities reinforce the hypothesis that these CSFGs are the closest analogs of significant contributors to the reionization of the intergalactic medium.}, archive = {J_ApJ}, author = {Intae Jung and Swara Ravindranath and Anne E. Jaskot and Henry C. Ferguson and Bethan L. James}, doi = {10.3847/1538-4357/adde49}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {4}, shortjournal = {The Astrophys. J.}, title = {Local analogs of potential ionizers of the intergalactic medium: Compact star-forming galaxies with intense c IV λ1550 emission}, volume = {988}, year = {2025}, }
• (2025). On the relation between the inclination angle of the accretion disk and the broad-line region in active galactic nuclei. ApJ, 988(1), 3. (www)

  @article{ , abstract = {Models of active galactic nuclei (AGN) often invoke a close physical association between the broad-line region (BLR) and the accretion disk. We evaluate this theoretical expectation by investigating the relationship between the inclination angle of the BLR ( θ BLR ) and the inclination angle of the inner accretion disk ( θ disk ). For a sample of eight AGN that have published values of θ BLR estimated from dynamical modeling of the BLR based on velocity-resolved reverberation mapping experiments, we analyze high-quality, joint XMM-Newton and NuSTAR X-ray observations to derive new, robust measurements of θ disk through broadband (0.3–78 keV) reflection spectroscopy. Mock spectra demonstrate that the results are generally not strongly affected by warm absorbers or the model used to fit the soft-band data. We find a strong, positive correlation between θ BLR and θ disk (Pearson correlation coefficient 0.856, p -value 0.007), although Monte Carlo simulations indicate that the level of significance is only marginal (<3 σ ). Nevertheless, the nearly linear relation between θ BLR and θ disk suggests a possible physical alignment between the accretion disk and the BLR. Future studies with a larger and more homogeneous sample are needed to confirm the correlation and refine our understanding of the structure and dynamics of the central regions of active galaxies.}, archive = {J_ApJ}, author = {Rong Du and Luis C. Ho and Yuanze Ding and Ruancun Li}, doi = {10.3847/1538-4357/addec8}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {3}, shortjournal = {The Astrophys. J.}, title = {On the relation between the inclination angle of the accretion disk and the broad-line region in active galactic nuclei}, volume = {988}, year = {2025}, }
• (2025). A cometary fluorescence model for the ν3 vibrational band of cyanogen. ApJ, 988(1), 2. (www)

  @article{ , abstract = {Cyanogen (C 2 N 2 ) has been suspected for a long time to be present in comets and to contribute to the creation of the CN radical. So far no observations with ground-based facilities have managed to detect this species, but the Rosetta mission, thanks to in situ observations with the ROSINA mass spectrometer, detected this species in the coma of 67P/Churyumov–Gerasimenko. To investigate its presence from infrared spectra in other comets, we developed a fluorescence model for the ν 3 fundamental band. From new laboratory high-resolution infrared spectra of cyanogen, we analyzed the region of the ν 3 band of C 2 N 2 , centered around 4.63 μ m (2158 cm −1 ). In addition to line positions and intensities, molecular parameters for the ground and excited vibrational state were obtained. These parameters allowed us to develop a fluorescence model for cyanogen. Line-by-line excitation rates of the ν 3 band of cyanogen in cometary comae are presented. An upper limit of the abundance of cyanogen in a spectrum of comet C/2022 E3 (ZTF) is discussed.}, archive = {J_ApJ}, author = {P. Hardy and P. Rousselot and C. Richard and V. Boudon and X. Landsheere and A. Voute and L. Manceron and F. Kwabia Tchana}, doi = {10.3847/1538-4357/addf3e}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {2}, shortjournal = {The Astrophys. J.}, title = {A cometary fluorescence model for the ν3 vibrational band of cyanogen}, volume = {988}, year = {2025}, }
• (2025). A wide-field map of ultracompact dwarfs in the coma cluster. ApJ, 988(1), 1. (www)

  @article{ , abstract = {A data set of 23,351 globular clusters (GCs) and ultracompact dwarfs (UCDs) in the Coma cluster of galaxies was built using Hubble Space Telescope Advanced Camera for Surveys data. Based on the standard magnitude cut of M V ≤ −11, a total of 523 UCD candidates are found within this data set of compact stellar systems (CSS). From a color–magnitude diagram analysis built using this catalog, we find a clear mass–magnitude relation extending marginally into the UCD parameter space. The luminosity function defined by this data set shows an excess of sources at bright magnitudes, suggesting a bimodal formation scenario for UCDs. We estimate the number of UCDs with a different origin than GC to be N UCD ≳ 32 ± 1. We derive the total number of CSS within the core (1 Mpc) of Coma to be N CSS ≈ 69,400 ± 1400. The radial distribution of UCDs in Coma shows that, like GCs, UCDs agglomerate around three giant ellipticals: NGC 4874, NGC 4889, and IC 4051. We find UCDs are more centrally concentrated around these three ellipticals than GCs. IC 4051 has a satellite population of UCDs similar to NGC 4874 and NGC 4889. We estimate only ∼14% of UCDs inhabit the intracluster space (ICUCD) between galaxies in the region, in comparison to ∼24% for GCs (ICGC). We find red (metal-rich) UCDs are more likely located closer to a host galaxy, with blue (metal-poor) UCDs showing a greater dispersion and lower average density in the region.}, archive = {J_ApJ}, author = {Richard T. Pomeroy and Juan P. Madrid and Conor R. O’Neill and Alexander T. Gagliano}, doi = {10.3847/1538-4357/addf4a}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {1}, shortjournal = {The Astrophys. J.}, title = {A wide-field map of ultracompact dwarfs in the coma cluster}, volume = {988}, year = {2025}, }
• (2025). High-energy neutrino signatures from pulsar remnants of binary neutron-star mergers: Coincident detection prospects with gravitational waves. ApJ, 987(2), 218. (www)

  @article{ , abstract = {Binary neutron-star (BNS) mergers are accompanied by multimessenger emissions, including gravitational wave (GW), neutrino, and electromagnetic signals. Some fraction of BNS mergers may result in a rapidly spinning magnetar as a remnant, which can enhance both the EM and neutrino emissions. In this study, we model the neutrino emissions from such systems and discuss the prospects for detecting the neutrinos coincident with GW signatures. We consider a scenario where a magnetar remnant drives a pulsar wind using its spin energy. The wind interacts with the surrounding kilonova ejecta, forming a nebula filled with nonthermal photons. Ions and nuclei extracted from the magnetar’s surface can be accelerated in the polar-cap and the termination-shock regions. We investigate the neutrino fluences resulting from photomeson interactions, where accelerated CR protons interact with the photons in the nebula. Our findings indicate that the peak neutrino fluence is ∼10 −2 GeV cm −2 for a source at 40 Mpc, which is reached approximately { \mathcal O }(1-10\,\mathrm{days}) post-merger. Finally, we examine the potential for GW-triggered stacking searches with IceCube-Gen2 using next-generation GW detectors such as the Cosmic Explorer (CE) and the Einstein Telescope (ET). We conclude that, assuming an optimistic neutrino emission model, a combination of CE+ET would offer a high probability of neutrino detection from these sources within an operational timescale of ∼20 yr. In case of nondetection, 2 σ level constraints on model parameters can be established within similar joint operation timescales.}, archive = {J_ApJ}, author = {Mainak Mukhopadhyay and Shigeo S. Kimura and Brian D. Metzger}, doi = {10.3847/1538-4357/adc913}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {218}, shortjournal = {The Astrophys. J.}, title = {High-energy neutrino signatures from pulsar remnants of binary neutron-star mergers: Coincident detection prospects with gravitational waves}, volume = {987}, year = {2025}, }
• (2025). GHOST commissioning science results. IV. chemodynamical analyses of milky way satellites sagittarius II and aquarius II. ApJ, 987(2), 217. (www)

  @article{ , abstract = {We present Gemini/GHOST high-resolution spectra of five stars observed in two low surface brightness Milky Way satellites, Sagittarius II (Sgr2) and Aquarius II (Aqu2). For Aqu2, the velocities and metallicities of the two stars are consistent with membership in a dark-matter-dominated ultra-faint dwarf galaxy (UFD). The chemical abundance ratios suggest inefficient star formation from only one or a few supernovae (e.g., low Na, Sr, Ba), and enriched potassium (K) from super-AGB stars. For Sgr2, the velocity and metallicity dispersions of its members are not clearly resolved, and our detailed chemical abundances show typical ratios for metal-poor stars, with low dispersions. There is only one exception—we report the discovery of an r -process enhanced star (Sgr 2584, [Eu/Fe] = +0.7 ± 0.2; thus, an r-I star). As r-I stars are found in both UFDs (Tuc III, Tuc IV, and Grus II) and globular clusters (M15 and M92), then this does not help to further classify the nature of Sgr2. Our exploration of Sgr2 demonstrates the difficulty in classifying some of the faintest (ambiguous) satellites. We advocate for additional diagnostics in analyzing the ambiguous systems, such as exploring radial segregation (by mass and/or chemistry), N -body simulations, and the need for dark matter to survive Galactic tidal effects. The spectra analyzed in this paper were taken as part of the GHOST commissioning observations, testing faint observation limits ( G < 18.8) and the single and double integrated field unit observing modes.}, archive = {J_ApJ}, author = {Daria Zaremba and Kim Venn and Christian R. Hayes and Raphaël Errani and Triana Cornejo and Jennifer Glover and Jaclyn Jensen and Alan W. McConnachie and Julio F. Navarro and John Pazder and Federico Sestito and André Anthony and Dave Andersen and Gabriella Baker and Timothy Chin and Vladimir Churilov and Ruben Diaz and Tony Farrell and Veronica Firpo and Manuel Gomez-Jimenez and David Henderson and Venu M. Kalari and Jon Lawrence and Steve Margheim and Bryan Miller and J. Gordon Robertson and Roque Ruiz-Carmona and Katherine Silversides and Karleyne Silva and Peter J. Young and Ross Zhelem}, doi = {10.3847/1538-4357/add5f9}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {217}, shortjournal = {The Astrophys. J.}, title = {GHOST commissioning science results. IV. chemodynamical analyses of milky way satellites sagittarius II and aquarius II}, volume = {987}, year = {2025}, }
• (2025). Circumplanetary disks are rare around planets at large orbital radii: A parameter survey of flow morphology around giant planets. ApJ, 987(2), 216. (www)

  @article{ , abstract = {We investigate how the formation and structure of circumplanetary disks (CPDs) vary with planet mass and protoplanetary disk aspect ratio. Using static mesh refinement and a near-isothermal equation of state, we perform a small parameter survey of hydrodynamic simulations with parameters appropriate for disk-embedded protoplanets at moderate to large orbital radii. We find that CPD formation occurs along a continuum, with “diskiness” increasing smoothly with planetary mass and decreasing disk aspect ratio. As expected from disk hydrostatic equilibrium arguments, the transition from envelope-dominated to disk-dominated structures is determined to first order by the ratio of the planetary Hill sphere radius to the disk scale height, but planets need to be significantly superthermal to host classical rotationally supported CPDs. The circularization radius of inflowing gas (as a fraction of the Hill sphere radius) shows an approximately quadratic power-law scaling with the ratio of planetary mass to the thermal mass. Compared to more physically complete radiation hydrodynamic simulations, our runs almost maximize the possibility for classical CPD formation, and hence define a plausible necessary condition for CPDs. The low abundance of detected CPDs in disks where planetary companions are inferred from substructure data may be due to a combination of the large scale height of the protoplanetary disk, and a low frequency of sufficiently massive protoplanets. Unless their CPDs cool below the local protoplanetary disk temperature, most of the wide-orbit giant planet population will be embedded in quasi-spherical envelopes that are hard to detect. Disks, and satellite systems, are more likely to form around smaller orbital separation planets.}, archive = {J_ApJ}, author = {Sabina Sagynbayeva and Rixin Li and Aleksandra Kuznetsova and Zhaohuan Zhu and Yan-Fei Jiang and Philip J. Armitage}, doi = {10.3847/1538-4357/add934}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {216}, shortjournal = {The Astrophys. J.}, title = {Circumplanetary disks are rare around planets at large orbital radii: A parameter survey of flow morphology around giant planets}, volume = {987}, year = {2025}, }
• (2025). A fast, analytic empirical model of the gaia data release 3 astrometric orbit catalog selection function. ApJ, 987(2), 215. (www)

  @article{ , abstract = {In 2022 June, the Gaia mission released a catalog of astrometric orbital solutions for 168,065 binary systems, by far the largest such catalog to date. The catalog’s selection function is difficult to characterize because of choices made in its construction. Understanding the catalog’s selection function is required to model and interpret its contents. We use a combination of analytic and empirical prescriptions to construct a function that computes the probability that a binary with a given set of properties would have been published in the Gaia Data Release 3 astrometric orbit catalog. This is a complementary approach to the more accurate but significantly more computationally expensive approach of El-Badry et al. We also construct a binary population synthesis model to validate our characterization of the selection function, finding good agreement with the actual Gaia NSS catalog, with the exception of the orbital eccentricity distribution. The NSS catalog suggests high-eccentricity orbits are relatively uncommon at intermediate periods 100 ≲ P orb ≲ 1000 days. As an example application of the selection function, we estimate the Gaia DR3 detection probabilities of the star + BH binaries Gaia BH1 and BH2, and find them to be 0.38 and 0.27, respectively. Compared to the values obtained by detailed modeling in El-Badry et al., the probabilities are identical for BH1, and within a factor of 2 for BH2. We also estimate the population of Sun-like star + BH binaries in the Galaxy to be ∼3000 for 100 < P orb < 400 days, <800 for 400 < P orb < 1000 days, and <12,000 for 1000 < P orb < 1500 days.}, archive = {J_ApJ}, author = {Casey Y. Lam and Kareem El-Badry and Joshua D. Simon}, doi = {10.3847/1538-4357/addac2}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {215}, shortjournal = {The Astrophys. J.}, title = {A fast, analytic empirical model of the gaia data release 3 astrometric orbit catalog selection function}, volume = {987}, year = {2025}, }
• (2025). Observational properties of thermal emission from relativistic jets embedded in active galactic nucleus disks. ApJ, 987(2), 214. (www)

  @article{ , abstract = {Relativistic jets can be produced within the accretion disk of an active galactic nucleus (AGN), leading to distinct thermal emission as they propagate through a dense disk environment. In this paper, we present a comprehensive study of the dynamical evolution of jets embedded in an AGN disk and their associated observational properties, focusing on scenarios in which jets either successfully break out of the disk or become choked. By modeling the jet-cocoon system propagation, we calculate the thermal emission contributions from the jet-head shock breakout, disk-cocoon, and jet-cocoon components. Our results reveal that soft X-ray flares are the most prominent observable signatures, with a duration ranging from O (10 2 ) s to O (10 5 ) s, occasionally exhibiting double-peaked light curves, whereas UV/optical flares are detectable only for powerful jets, persisting for several days to tens of days. This thermal emission serves as a critical electromagnetic counterpart to jet-producing events and provides insights into jet dynamics and AGN disk properties. Our findings highlight the importance of multiwavelength follow-up observations to establish a diagnostic paradigm for candidate electromagnetic counterpart identification of AGN-embedded events and to distinguish thermal flares from AGN background variability.}, archive = {J_ApJ}, author = {Ken Chen and Zi-Gao Dai}, doi = {10.3847/1538-4357/addb48}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {214}, shortjournal = {The Astrophys. J.}, title = {Observational properties of thermal emission from relativistic jets embedded in active galactic nucleus disks}, volume = {987}, year = {2025}, }
• (2025). Investigating turbulence effects on magnetic reconnection rates through 3D resistive magnetohydrodynamic simulations. ApJ, 987(2), 213. (www)

  @article{ , abstract = {We investigate the impact of turbulence on magnetic reconnection through high-resolution 3D magnetohydrodynamic (MHD) simulations, spanning Lundquist numbers from S = 10 3 to 10 6 . Building on the A. Lazarian & E. T. Vishniac theory, which asserts reconnection rate independence from ohmic resistivity, we introduce small-scale perturbations until t = 0.1 t A . Even after the perturbations cease, turbulence persists, resulting in sustained high reconnection rates of V rec / V A ∼ 0.03–0.08. These rates exceed those generated by resistive tearing modes (plasmoid chain) in 2D and 3D MHD simulations by factors of 5–6. Our findings match observations in solar phenomena and previous 3D MHD global simulations of solar flares, accretion flows, and relativistic jets. The simulations show a steady-state fast reconnection rate compatible with the full development of turbulence in the system, demonstrating the robustness of the process in turbulent environments. We confirm reconnection rate independence from the Lundquist number, supporting Lazarian and Vishniac’s theory of fast turbulent reconnection. Additionally, we find a mild dependence of V rec on the plasma– β parameter, decreasing from 0.036 to 0.028 (in Alfvén units) as β increases from 2.0 to 64.0 for simulations with a Lundquist number of 10 5 . Lastly, we explore the magnetic Prandtl number’s (Pr m = ν / η ) influence on the reconnection rate and find it negligible during the turbulent regime across the range tested, from Pr m = 1 to 60.}, archive = {J_ApJ}, author = {Giovani H. Vicentin and Grzegorz Kowal and Elisabete M. de Gouveia Dal Pino and Alex Lazarian}, doi = {10.3847/1538-4357/addc62}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {213}, shortjournal = {The Astrophys. J.}, title = {Investigating turbulence effects on magnetic reconnection rates through 3D resistive magnetohydrodynamic simulations}, volume = {987}, year = {2025}, }
• (2025). The structure and evolution of a high-mass stellar merger in the hertzsprung gap. ApJ, 987(2), 212. (www)

  @article{ , abstract = {Post-main-sequence binary mergers are a common evolutionary pathway for massive stars, but the effects of merging on the long-term structure and evolution of the resulting star are a matter of active debate. Furthermore, the way in which merger products are modeled in 1D is not uniform. We present the evolution of an 11 M ⊙ and 6.6 M ⊙ binary on an 11 days orbit that merges while the primary is crossing the Hertzsprung gap. We construct the merger product either by rapidly accreting the secondary onto the surface of the primary or by injecting material from the secondary deeper into the primary via entropy sorting. We then evolve them to carbon ignition, comparing their interior structures at this stage. We find that all merger products experience an extended blue supergiant phase and have undermassive helium cores and low carbon mass fractions compared to single and stripped stars. However, the evolution of central density, temperature, and composition in the entropy-sorted model is distinct from those of the rapid-accretion models.}, archive = {J_ApJ}, author = {Rachel A. Patton and Marc H. Pinsonneault and Todd A. Thompson}, doi = {10.3847/1538-4357/addd0f}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {212}, shortjournal = {The Astrophys. J.}, title = {The structure and evolution of a high-mass stellar merger in the hertzsprung gap}, volume = {987}, year = {2025}, }
• (2025). Total power and low-energy cutoff time evolution of solar flare accelerated electrons using X-ray observations and warm-target model. ApJ, 987(2), 211. (www)

  @article{ , abstract = {A primary characteristic of solar flares is the efficient acceleration of electrons to nonthermal deka-keV energies. While hard X-ray (HXR) observation of bremsstrahlung emission serves as the key diagnostic of these electrons. In this study, we investigate the time evolution of flare-accelerated electrons using the warm-target model. This model, unlike the commonly used cold-target model, can determine the low-energy cutoff in the nonthermal electron distribution, so that the energetics of nonthermal electrons can be deduced more accurately. Here, we examine the time-evolution of nonthermal electrons in flares well-observed by the Reuven Ramaty High Resolution Solar Spectroscopic Imager and the Solar Orbiter spacecraft (using the Spectrometer/Telescope for Imaging X-rays instrument). Using spectroscopic and imaging HXR observations, the time evolution of the low-energy cutoff of the accelerated electron distribution, the total power of nonthermal electrons, total rate of nonthermal electrons, and excess thermal emission measure from the nonthermal electrons are investigated. We find that the time profile of the low-energy cutoff of the accelerated electron distribution shows a high-low-high trend around the HXR bursts of flares, while the time evolution of the total rate of injected electrons shows a low-high-low behavior. Although the total power of nonthermal electrons is sensitive to the cutoff energy, the temporal variation of the flare power follows the temporal variation of the acceleration rate. We further find that the highest contribution of the excess thermal emission measure coming from thermalization of injected electrons takes place around the HXR peak.}, archive = {J_ApJ}, author = {Debesh Bhattacharjee and Eduard P. Kontar and Yingjie Luo}, doi = {10.3847/1538-4357/addf44}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {211}, shortjournal = {The Astrophys. J.}, title = {Total power and low-energy cutoff time evolution of solar flare accelerated electrons using X-ray observations and warm-target model}, volume = {987}, year = {2025}, }
• (2025). A be star + he star binary as an indicator of a binary mass transfer phase. ApJ, 987(2), 210. (www)

  @article{ , abstract = {The rapid rotation of Be stars is supposed to mainly originate from binary evolution. In recent years, more and more Be stars with helium (He) star companions have been discovered, which provides a significant opportunity to study binary interaction physics. In this work, we perform binary population synthesis with an updated binary mass transfer stability criterion and try to understand the details of mass transfer processes by constructing a series of Be star + He star (BeHe) binary populations. We found that the simulations and the observations can be divided into two groups according to the masses of components, corresponding to the two distinct evolutionary processes during the mass transfer. In particular, we found that the mass ratios of BeHe binaries may be taken as a probe of the initial mass ratios of the primordial binaries. Moreover, the results suggest that a higher mass transfer efficiency (≳0.5) supports the observations better. The simulations predicted too many Be star binaries experiencing case B mass transfer, which conflicts with the observations. The reason is due to either observational selection effects or unclear physical factors.}, archive = {J_ApJ}, author = {Yuchen Bao and Zhenwei Li and Hongwei Ge and Xuefei Chen and Zhanwen Han}, doi = {10.3847/1538-4357/addfd8}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {210}, shortjournal = {The Astrophys. J.}, title = {A be star + he star binary as an indicator of a binary mass transfer phase}, volume = {987}, year = {2025}, }
• (2025). Regarding the detection of interstellar c4 and c5 molecules. ApJ, 987(2), 209. (www)

  @article{ , abstract = {Analysis of very high signal-to-noise ratio (S/N) spectra of reddened stars allowed us to determine an upper limit (UL) of the column density N (C 4 ). We developed a robust calibration of the N (C 4 ) based on the C 4 gas-phase spectrum profile at 3789 Å. The UL of the column density can be calculated using the equation N UL (C 4 ) = 8.963 × 10 15 /(S/N), where S/N is in the wavelength range ∼3790 Å. Nondetection of this molecule was confirmed in stars exhibiting a high abundance of C 2 and C 3 molecules. According to our calibration, assuming an optimistic estimate of the ratio \frac{N({{\rm{C}}}_{3})}{N({{\rm{C}}}_{4})} = 10, even for the star HD 147889 with the highest known to date column density of C 3 , the S/N required for detecting the C 4 molecule is about 12,000 per pixel, which is a challenging task. Despite this tough conclusion regarding the possibility of detecting the interstellar molecule C 4 , we also tried to find a link between known lines of C 5 at 4975 and 5109 Å and weak interstellar features. The expected C 5 4975 Å feature coincides well with weak diffuse interstellar band (DIB) 4975, while the search for the 5109 Å C 5 band is badly conditioned by the overlap with a broad spectral feature, which is a blend of stellar and interstellar lines. However, we found a rather good correlation between the equivalent width of DIB 4975 and N (C 2 ), making the search for C 5 not hopeless. If DIB 4975 is formed by C 5 , its column density is only 2 times lower than that of C 3 .}, archive = {J_ApJ}, author = {G. A. Galazutdinov and E. I. Kazanina and J. Krełowski}, doi = {10.3847/1538-4357/ade13d}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {209}, shortjournal = {The Astrophys. J.}, title = {Regarding the detection of interstellar c4 and c5 molecules}, volume = {987}, year = {2025}, }
• (2025). Sgr a* spin and mass estimates through the detection of multiple extremely large mass ratio inspirals. ApJ, 987(2), 208. (www)

  @article{ , abstract = {We analyze the parameter estimation accuracy that can be achieved for the mass and spin of Sgr A*, the supermassive black hole in our Galactic center, by detecting multiple extremely large mass ratio inspirals (XMRIs). XMRIs are formed by brown dwarfs inspiraling into a supermassive black hole, thus emitting gravitational waves (GWs) inside the detection band of future space-based detectors such as LISA and TianQin. Theoretical estimates suggest the presence of approximately 10 XMRIs emitting detectable GWs, making them some of the most promising candidates for space-based GW detectors. Our analysis indicates that even if individual sources have low signal-to-noise ratios (SNRs; ≈10), high-precision parameter estimates can still be achieved by detecting multiple sources. In this case, the accuracy of the parameter estimates increases by approximately 1–2 orders of magnitude at least. Moreover, by analyzing a small sample of 400 initial conditions for XMRIs formed in the Galactic center, we estimate that almost 80% of the detectable XMRIs orbiting Sgr A* will have eccentricities between 0.43 and 0.95 and an SNR ∈ [10, 100]. The remaining ∼20% of the sources have an SNR ∈ [100, 1000] and eccentricities ranging from 0.25 to 0.92. Additionally, some XMRIs with high SNRs are far from being circular. These loud sources with SNR ≈ 1000 can have eccentricities as high as e ≈ 0.7; although their detection chances are low, representing ≲2% of the detectable sources, their presence is not ruled out.}, archive = {J_ApJ}, author = {Verónica Vázquez-Aceves and Yiren Lin and Alejandro Torres-Orjuela}, doi = {10.3847/1538-4357/ade149}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {208}, shortjournal = {The Astrophys. J.}, title = {Sgr a* spin and mass estimates through the detection of multiple extremely large mass ratio inspirals}, volume = {987}, year = {2025}, }
• (2025). Hydroxylated mg-rich amorphous silicates as catalysts for molecular hydrogen formation in the interstellar medium. ApJ, 987(2), 207. (www)

  @article{ , abstract = {We present results from an experimental study on the interaction of atomic deuterium with magnesium-rich amorphous enstatite- and forsterite-type silicates. Infrared spectroscopy was used to examine the process. During deuterium atom exposure, deuteroxyl group formation was observed. The cross section for OD group formation, estimated from the OD stretching band intensity with D atom fluence, is σ f ,OD = 4.2 × 10 −18 cm 2 for both silicates. HD (D 2 ) molecules form via D atom abstraction of chemisorbed H (D) atoms from OH (OD) groups, with a cross section of {\sigma }_{f,{{\rm{D}}}_{2}} = 7.0 × 10 −18 cm 2 . Quantum-chemical calculations on enstatite and forsterite amorphous nanoclusters were used to analyze chemisorption and abstraction energies of hydrogen atoms. The formation of OH groups on forsterite is barrierless, while enstatite has a small energy barrier. H 2 abstraction from hydroxyl groups is barrierless in both silicates. The results support our interpretation of IR spectral changes during D atom exposure as addition and exchange reactions, with catalytic molecular deuterium formation. These findings, obtained at 300 K, are relevant to astrophysical environments like photodissociation regions and interstellar clouds at lower temperatures. Amorphous silicates, like carbon grains, undergo hydrogenation in the diffuse interstellar medium due to interactions with atomic hydrogen and UV photons. The detection of these components on comet 67P/Churyumov–Gerasimenko connects primitive solar system objects to interstellar dust, offering new insights into their evolution.}, archive = {J_ApJ}, author = {V. Mennella and T. Suhasaria and B. Kerkeni and G. Ouerfelli}, doi = {10.3847/1538-4357/ade2d3}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {207}, shortjournal = {The Astrophys. J.}, title = {Hydroxylated mg-rich amorphous silicates as catalysts for molecular hydrogen formation in the interstellar medium}, volume = {987}, year = {2025}, }
• (2025). A gravitational-wave-detectable candidate type ia supernova progenitor. ApJ, 987(2), 206. (www)

  @article{ , abstract = {Type Ia supernovae (SNe Ia), critical for studying cosmic expansion, arise from thermonuclear explosions of white dwarfs, but their precise progenitor pathways remain unclear. Growing evidence supports the “double-degenerate scenario,” where two white dwarfs interact. The absence of nondegenerate companions capable of explaining the observed SN Ia rate, along with observations of hypervelocity white dwarfs, interpreted as surviving companions of such systems, provide compelling evidence for this scenario. Upcoming millihertz gravitational-wave observatories like the Laser Interferometer Space Antenna (LISA) are expected to detect thousands of double-degenerate systems, though the most compact known candidate SN Ia progenitors produce marginally detectable signals. Here, we report observations of ATLAS J1138-5139, a binary white dwarf system with an orbital period of just 28 minutes. Our analysis reveals a 1 M ☉ carbon–oxygen white dwarf accreting from a high-entropy helium-core white dwarf. Given its mass, the accreting carbon–oxygen white dwarf is poised to trigger a typical-luminosity SN Ia within a few million years, to evolve into a stably transferring AM Canum Venaticorum (or AM CVn) system, or undergo a merger into a massive white dwarf. ATLAS J1138-5139 provides a rare opportunity to calibrate binary evolution models by directly comparing observed orbital parameters and mass-transfer rates closer to merger than any known SN Ia progenitor. Its compact orbit ensures detectability by LISA, demonstrating the potential of millihertz gravitational-wave observatories to reveal a population of SN Ia progenitors on a Galactic scale, paving the way for multimessenger studies offering insights into the origins of these cosmologically significant explosions.}, archive = {J_ApJ}, author = {Emma T. Chickles and Kevin B. Burdge and Joheen Chakraborty and Vik S. Dhillon and Paul Draghis and James Munday and Saul A. Rappaport and John Tonry and Evan B. Bauer and Alex J. Brown and Noel Castro and Deepto Chakrabarty and Martin Dyer and Kareem El-Badry and Anna Frebel and Gabor Furesz and James Garbutt and Matthew J. Green and Aaron Householder and Scott A. Hughes and Daniel Jarvis and Erin Kara and Mark R. Kennedy and Paul Kerry and Stuart P Littlefair and James McCormac and Geoffrey Mo and Mason Ng and Steven Parsons and Ingrid Pelisoli and Eleanor Pike and Thomas A. Prince and George R. Ricker and Jan van Roestel and David Sahman and Ken J. Shen and Robert A. Simcoe and Pier-Emmanuel Tremblay and Andrew Vanderburg and Tin Long Sunny Wong}, doi = {10.3847/1538-4357/add34c}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {206}, shortjournal = {The Astrophys. J.}, title = {A gravitational-wave-detectable candidate type ia supernova progenitor}, volume = {987}, year = {2025}, }
• (2025). A new LISA-detectable type ia supernova progenitor in the southern sky: SMSS j1138−5139. ApJ, 987(2), 205. (www)

  @article{ , abstract = {We present the discovery and analysis of a nearby eclipsing ultracompact accreting binary SMSS J1138−5139, the first well-constrained LISA-detectable Type Ia supernova progenitor. Our time-series optical spectroscopy identifies its orbital period through radial velocity monitoring at {P}_{\mathrm{orb,RV}}=27.682\,\mathrm{minutes} , twice the photometric period seen in 2 minute cadence data from TESS Sector 37. We model our optical spectroscopy together with new simultaneous multiband time-series photometry from Gemini to place constraints on the binary parameters. Our light-curve modeling finds that SMSS J1138−5139 contains an M 2 = 0.25 ± 0.01 M ⊙ pre-white-dwarf donor with a massive M 1 = 1.02 ± 0.05 M ⊙ white dwarf accretor at orbital inclination ​​​​​​ i=88\mathop{.}\limits^{\circ }6\pm 0\mathop{.}\limits^{\circ }1 . Based on our photometrically derived system parameters, we expect that gravitational-wave radiation will drive SMSS J1138−5139 to a merger within τ = 5.7 ± 0.3 Myr and result in a Type Ia supernova. Even without a direct merger event, the component masses of SMSS J1138−5139 and active hydrogen accretion suggest that eventual helium accretion will likely also trigger a Type Ia supernova explosion through the dynamically driven double-degenerate double-detonation (D6) channel. We expect LISA to detect the gravitational-wave emission from SMSS J1138−5139 with a signal-to-noise ratio of 7–10 after a 48 month mission.}, archive = {J_ApJ}, author = {Alekzander Kosakowski and Matti Dorsch and Warren R. Brown and Thomas Kupfer and Fatma Ben Daya and Mukremin Kilic}, doi = {10.3847/1538-4357/add1cf}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {205}, shortjournal = {The Astrophys. J.}, title = {A new LISA-detectable type ia supernova progenitor in the southern sky: SMSS j1138−5139}, volume = {987}, year = {2025}, }
• (2025). Cosmic-ray-driven galactic winds with resolved interstellar medium and ion-neutral damping. ApJ, 987(2), 204. (www)

  @article{ , abstract = {Feedback processes in galaxies dictate their structure and evolution. Baryons can be cycled through stars, which inject energy into the interstellar medium in supernova explosions, fueling multiphase galactic winds. Cosmic rays (CRs) accelerated at supernova remnants are an important component of feedback. CRs can effectively contribute to wind driving; however, their impact heavily depends on the assumed CR transport model. We run high-resolution “tallbox” simulations of a patch of a galactic disk using the moving mesh magnetohydrodynamics code A repo , including varied CR implementations and the C risp nonequilibrium thermochemistry model. We characterize the impact of CR feedback on star formation and multiphase outflows. While CR-driven winds are able to supply energy to a global-scale wind, a purely thermal wind loses most of its energy by the time it reaches 3 kpc above the disk midplane. We further find that the adopted CR transport model significantly affects the steady state of the wind. In the model with CR advection, streaming, diffusion, and nonlinear Landau damping, CRs provide very strong feedback. Additionally, accounting for ion-neutral damping (IND) decouples CRs from the cold ISM, which reduces the impact of CRs on the star formation rate. Nevertheless, CRs in this most realistic model are able to accelerate warm gas and levitate cool gas in the wind but have little effect on cold gas and hot gas. This model displays moderate mass loading and significant CR energy loading, demonstrating that IND does not prevent CRs from providing effective feedback.}, archive = {J_ApJ}, author = {Brandon Sike and Timon Thomas and Mateusz Ruszkowski and Christoph Pfrommer and Matthias Weber}, doi = {10.3847/1538-4357/adda3d}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {204}, shortjournal = {The Astrophys. J.}, title = {Cosmic-ray-driven galactic winds with resolved interstellar medium and ion-neutral damping}, volume = {987}, year = {2025}, }
• (2025). Discovery of a weak CN spectral absorption feature in red supergiant stars in the andromeda (M31) and triangulum (M33) galaxies. ApJ, 987(2), 203. (www)

  @article{ , abstract = {Using Keck DEIMOS spectra of stars in the Andromeda (M31) and Triangulum (M33) galaxies, selected from the large multiband (near-ultraviolet, visible light, and near-infrared) Hubble Space Telescope surveys PHAT and PHATTER, respectively, we have identified a subset of stars that contain a previously unnoticed weak spectral absorption feature around 8000 Å (0.8 μ m). This absorption feature appears to be associated with the cyanogen (CN) molecule. Strong CN spectral absorption is a standard feature of carbon stars, which are thought to be intermediate mass (2–3 M ⊙ ) stars with C/O > 1 in the thermally pulsating asymptotic giant branch phase of stellar evolution. However, the stars that are the focus of this paper are characterized by a weak version of this CN spectral absorption feature in a spectrum that is otherwise dominated by normal O-rich spectral absorption lines such as TiO and/or the Ca near-infrared triplet. We have dubbed these stars “weak CN” stars. We present an automated method for identifying weak CN stars in M31 and M33, and examine their photometric properties in relation to model isochrones and stellar tracks. We find that weak CN stars tend to be fairly localized in color–magnitude space, and appear to be red supergiant stars with masses ranging from 5 to 10 M ⊙ , overall lifetimes of about 40–50 Myr, and currently in the core He burning phase of stellar evolution.}, archive = {J_ApJ}, author = {Puragra Guhathakurta and Douglas Grion Filho and Antara R. Bhattacharya and Lara R. Cullinane and Julianne J. Dalcanton and Karoline M. Gilbert and Leo Girardi and Anika Kamath and Evan N. Kirby and Arya Maheshwari and Paola Marigo and Alexandra Masegian and Amanda C. N. Quirk and Rachel Raikar and Stanley M. Rinehart V and Caelum J. Rodriguez and Benjamin F. Williams}, doi = {10.3847/1538-4357/adcc2c}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {203}, shortjournal = {The Astrophys. J.}, title = {Discovery of a weak CN spectral absorption feature in red supergiant stars in the andromeda (M31) and triangulum (M33) galaxies}, volume = {987}, year = {2025}, }
• (2025). Cyclic zoom: Multiscale GRMHD modeling of black hole accretion and feedback. ApJ, 987(2), 202. (www)

  @article{ , abstract = {We present a “cyclic zoom” method to capture the dynamics of accretion flows onto black holes across a vast range of spatial and temporal scales in general relativistic magnetohydrodynamic (GRMHD) simulations. In this method, we cyclically zoom out (derefine) and zoom in (refine) the simulation domain while using a central mask region containing a careful treatment of the coarsened fluid variables to preserve the small-scale physics, in particular the magnetic field dynamics. The method can accelerate GRMHD simulations by ≳10 5 times for problems with large-scale separation. We demonstrate the validity of the technique using a series of tests, including spherically symmetric Bondi accretion, the Blandford–Znajek monopole, magnetized turbulent Bondi accretion, accretion of a magnetized rotating torus, and the long-term evolution of an accreting torus about both Schwarzschild and Kerr black holes. As applications, we simulate Bondi and rotating torus accretion onto black holes from galactic scales, covering an extremely large dynamic range. In Bondi accretion, the accretion rate is suppressed relative to the Bondi rate by \sim {(10{r}_{{\rm{g}}}/{r}_{{\rm{B}}})}^{1/2} with a feedback power of \sim 0.01\dot{M}{c}^{2} for vanishing spin and \sim 0.1\dot{M}{c}^{2} for spin a ≈ 0.9. In the long-term evolution of a rotating torus, the accretion rate decreases with time as \dot{M}\propto {t}^{-2} on timescales much longer than the viscous timescale, demonstrating that our method can capture not only quasi-steady problems but also secular evolution. Our new method likewise holds significant promise for applications to many other problems that need to cover vast spatial and temporal scales.}, archive = {J_ApJ}, author = {Minghao Guo and James M. Stone and Eliot Quataert and Volker Springel}, doi = {10.3847/1538-4357/add1da}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {202}, shortjournal = {The Astrophys. J.}, title = {Cyclic zoom: Multiscale GRMHD modeling of black hole accretion and feedback}, volume = {987}, year = {2025}, }
• (2025). An investigation of the evolution of heliosheath energetics using a pressure enhancement event observed by IBEX. ApJ, 987(2), 201. (www)

  @article{ , abstract = {During solar cycle 24, an increase in the solar wind (SW) dynamic pressure in late 2014 caused a sharp increase in the heliospheric energetic neutral atom (ENA) flux that was seen by the Interstellar Boundary Explorer (IBEX) at 1 au in late 2016. We study the variation of the ENA energy spectra and temperature in the heliosheath (HS) and compare it with the changes in line-of-sight-integrated ENA pressure, SW number density, speed, and SW dynamic pressure to understand the detailed physics of the energetic evolution of the HS. We use an improved map-making method and a newly developed ribbon-separation technique to obtain these physical parameters from IBEX-Hi ENA data. We find that the pressure enhancement in SW dynamic pressure leads to an increase in HS pressure, which peaks in 2018 before decreasing. The temperature in the HS steadily rises due to the SW pressure enhancement and it does not show any signs of returning to the pre-enhancement value. This indicates that hot HS plasma persists even after the pressure in the HS has started to go down. After the pressure enhancement starts dissipating, a split in the 4.3 keV ENA maps is observed due to a decrease in flux close to equator. We find that this is probably caused by a decrease in SW speed near the equator, which seems to be due to the latitudinal ordering of the SW from the opening of polar coronal holes.}, archive = {J_ApJ}, author = {Nehpreet K. Walia and Daniel B. Reisenfeld and Lauren J. Beesley and Paul H. Janzen and Thomas K. Kim and Asher S. Merrill and Sung Jun Noh and Dave Osthus and Eric J. Zirnstein}, doi = {10.3847/1538-4357/add476}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {201}, shortjournal = {The Astrophys. J.}, title = {An investigation of the evolution of heliosheath energetics using a pressure enhancement event observed by IBEX}, volume = {987}, year = {2025}, }
• (2025). Varstrometry for dual active galactic nuclei using radio interferometry: VaDAR with the VLBA. ApJ, 987(2), 200. (www)

  @article{ , abstract = {Multiple active galactic nuclei (multi-AGN) are a known result of galaxy mergers. Therefore, they are an important tool for studying the formation and dynamical evolution of galaxies and supermassive black holes. A novel method for the selection of multi-AGN leverages the exquisite positional accuracy of Gaia to detect astrometrically variable quasars. Previous work has paired this method with radio interferometry on subarcsecond scales. In this paper, we present a follow-up study of seven astrometrically variable quasars from the pilot sample using the Very Long Baseline Array (VLBA). We targeted these seven quasars with the VLBA at 2.0–2.4 GHz ( S band) and 8.0–8.4 GHz ( X band), reaching milliarcsecond resolutions, in order to study the radio properties at smaller scales and to constrain the origin of the astrometric variability. The new observations are also used to identify significant radio-optical offsets in all seven objects, suggesting that many astrometrically variable quasars also exhibit significant radio-optical offsets. We find that four of the seven sources are possible candidate multi-AGN based on their radio properties and radio-optical offsets. Overall, we use this follow-up study to constrain the smaller-scale radio properties of this sample of astrometrically variable quasars, and continue to explore the use of this method in the field of multi-AGN.}, archive = {J_ApJ}, author = {Emma Schwartzman and Paula Fudolig and Tracy E. Clarke and Kristina Nyland and Nathan J. Secrest and Ryan W. Pfeifle and Henrique Schmitt and Shobita Satyapal and Barry Rothberg}, doi = {10.3847/1538-4357/add47c}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {200}, shortjournal = {The Astrophys. J.}, title = {Varstrometry for dual active galactic nuclei using radio interferometry: VaDAR with the VLBA}, volume = {987}, year = {2025}, }
• (2025). A global census of metals in the universe. ApJ, 987(2), 199. (www)

  @article{ , abstract = {We present a census of the mass density of metals and their evolution with cosmic time on a global scale throughout the Universe, synthesizing robust estimates of metals in stars, hot intracluster gas, and gaseous absorbers tracing neutral gas as well as ionized gas in the circumgalactic and intergalactic media. We observe an order of magnitude increase in the stellar metal mass density from z ∼ 2.5 to 0.7, over which time stars emerge as the most important metal reservoir at low redshifts, housing ∼30% of the total expected metal density at z ∼ 0.1. Hot virialized intracluster/intragroup gas accounts for ∼15% and 10% of metals at z ∼ 0.1 and 0.7, respectively. Using metallicity measurements from the COS CGM Compendium, KODIAQ-Z, and the HD-LLS surveys covering redshifts z < 1 to z ∼ 2–3.5, we investigate the global distribution of metals in extragalactic cool ionized gas as a function of H i column density. During the period from z ≈ 3 to z < 1, the global metal density of cool ( T ∼ 10 4−5 K) gas has doubled. However, the fractional contribution of the ionized gas to the total expected metal density decreased from ∼20% at z ∼ 3 to ∼4% at z < 1. The cosmic metal density of all gas phases has increased with cosmic time, reflecting an “inside-out” metal dispersion by feedback mechanisms and galactic outflows.}, archive = {J_ApJ}, author = {Saloni Deepak and J. Christopher Howk and Nicolas Lehner and Céline Péroux}, doi = {10.3847/1538-4357/add732}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {199}, shortjournal = {The Astrophys. J.}, title = {A global census of metals in the universe}, volume = {987}, year = {2025}, }
• (2025). Lyman-break galaxies in the megaparsec-scale environments around three z ∼ 7.5 quasars with JWST imaging. ApJ, 987(2), 198. (www)

  @article{ , abstract = {We study the megaparsec-scale environments of the three highest-redshift luminous quasars at z ≥ 7.5 (J031343.84-180636.40, J134208.11+092838.61, and J100758.27+211529.21) to understand their connection to large-scale structure. Cosmological simulations show that these early supermassive black holes are expected to form in the most massive dark matter halos. Therefore, it is expected that they are anchors of galaxy overdensities if luminous matter traces the underlying dark matter structure of the Universe. Using JWST NIRCam (F090W/F115W/F250M/F360M/F430M) imaging, we observe the large-scale structure out to ∼13 comoving Mpc (cMpc) around these quasars. We select F090W-dropout Lyman-break galaxies (LBGs) and F430M-excess [O iii ] emitters in the three fields. We find 18, 21, and 6 LBG candidates in the fields of J0313, J1342, and J1007, respectively, resulting in a wide range of overdensities (1 + δ ∼ 19, 24, and 7). The photometric redshifts indicate serendipitous foreground and background overdensities in the J0313 field. The joint angular autocorrelation of the combined LBG sample shows significant clustering on <1.8 cMpc scales, demonstrating that the selected galaxies are likely associated with the large-scale structure surrounding the quasars. This first systematic study of z ∼ 7.5 quasars shows a diverse set of quasar environments at the onset of their formation, providing empirical data to help constrain theoretical predictions of early structure formation.}, archive = {J_ApJ}, author = {Maria Pudoka and Feige Wang and Xiaohui Fan and Jinyi Yang and Jaclyn Champagne and Zijian Zhang and Sofía Rojas-Ruiz and Eduardo Bañados and Silvia Belladitta and Sarah E. I. Bosman and Anna-Christina Eilers and Xiangyu Jin and Hyunsung D. Jun and Mingyu Li and Weizhe Liu and Chiara Mazzucchelli and Jan-Torge Schindler and Julien Wolf and Yunjing Wu}, doi = {10.3847/1538-4357/add88f}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {198}, shortjournal = {The Astrophys. J.}, title = {Lyman-break galaxies in the megaparsec-scale environments around three z ∼ 7.5 quasars with JWST imaging}, volume = {987}, year = {2025}, }
• (2025). The ALMA-ATOMS survey: Exploring protostellar outflows in HC3N. ApJ, 987(2), 197. (www)

  @article{ , abstract = {We present the first systematic study of bipolar outflows using HC 3 N as a tracer in a sample of 146 massive star-forming regions from the Atacama Large Millimeter/submillimeter Array Three-millimeter Observations of Massive Star-forming Regions (ATOMS) survey. Protostellar outflows arise at the initial stage of star formation as a consequence of active accretion. In general, these outflows play a pivotal role in regulating the star formation processes by injecting energetic material in the parent molecular clouds. In this process, lower velocity components of outflows contain a significant portion of the energy. However, extraction of these components is difficult because the corresponding gas is often mixed with that of the ambient cloud. In our sample, we identified 44 bipolar outflows and one explosive outflow in HC 3 N ( J = 11–10). The host clumps of these outflows are found to be at different evolutionary stages, suggesting that outflows in HC 3 N are detectable in different stages of star formation. In addition, the noncorrelation of HC 3 N outflows with clump evolutionary stages suggests that HC 3 N is an unbiased tracer of outflows. Analyses revealed that HC 3 N performs slightly better in detecting low-velocity components of outflows than traditionally employed tracers such as SiO. The derived outflow parameters (i.e., outflow mass, momentum, and energy) show moderate correlations with clump mass and luminosity. Our analysis of outflow opening angles and position–velocity diagrams across the outflow lobes show that, HC 3 N is not only a good tracer of low-velocity outflows but can also detect high-velocity collimated outflows. Overall, this study indicates that HC 3 N can be used as a complementary outflow tracer along with the traditionally known outflow tracers, particularly in the detection of the low-velocity components of outflows.}, archive = {J_ApJ}, author = {Ariful Hoque and Tapas Baug and Lokesh K. Dewangan and Mika Juvela and Anandmayee Tej and Paul F. Goldsmith and Pablo García and Amelia M. Stutz and Tie Liu and Chang Won Lee and Fengwei Xu and Patricio Sanhueza and N. K. Bhadari and K. Tatematsu and Xunchuan Liu and Hong-Li Liu and Yong Zhang and Xindi Tang and Guido Garay and Ke Wang and Siju Zhang and L. Viktor Tóth and Hafiz Nazeer and Jihye Hwang and Prasanta Gorai and Leonardo Bronfman and Swagat Ranjan Das and Tirthendu Sinha}, doi = {10.3847/1538-4357/add928}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {197}, shortjournal = {The Astrophys. J.}, title = {The ALMA-ATOMS survey: Exploring protostellar outflows in HC3N}, volume = {987}, year = {2025}, }
• (2025). Reverberation mapping data of NGC 5548 imply a multicomponent broad-line region. ApJ, 987(2), 196. (www)

  @article{ , abstract = {Line broadening and variability are observational hallmarks of active galactic nuclei (AGN) which allow us to measure supermassive black hole masses as well as constrain the geometry and kinematics of the emitting gas, with the most precise measurements requiring a degree of modeling. Two popular models of the broad-line region (BLR) describe the emitting gas as either a distribution of puffed-up clouds or a thin disk with strong velocity gradients. As we show in this work, key features in the reverberation mapping data set obtained by the AGN-STORM team in NGC 5548 cannot be accounted for by either simple model. In several emission lines the observed broad-line profile has a single peak yet the delay profile has a distinct double peak, strongly motivating a BLR with emission from multiple components. We demonstrate a few possibilities that may alleviate the tension and better represent the true nature of the broad-line-emitting gas in NGC 5548 and beyond.}, archive = {J_ApJ}, author = {Kirk Long and Jason Dexter}, doi = {10.3847/1538-4357/adda38}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {196}, shortjournal = {The Astrophys. J.}, title = {Reverberation mapping data of NGC 5548 imply a multicomponent broad-line region}, volume = {987}, year = {2025}, }
• (2025). PECCARY: A novel approach for characterizing orbital complexity, stochasticity, and regularity. ApJ, 987(2), 195. (www)

  @article{ , abstract = {Permutation Entropy and statistiCal Complexity Analysis for astRophYsics (PECCARY) is a computationally inexpensive, statistical method by which any time series can be characterized as predominantly regular, complex, or stochastic. Elements of the PECCARY method have been used in a variety of physical, biological, economic, and mathematical scenarios, but have not yet gained traction in the astrophysical community. This study introduces the PECCARY technique with the specific aims to motivate its use in and optimize it for the analysis of astrophysical orbital systems. PECCARY works by decomposing a time-dependent measure, such as the x -coordinate or orbital angular momentum time series, into ordinal patterns. Due to its unique approach and statistical nature, PECCARY is well suited for detecting preferred and forbidden patterns (a signature of chaos), even when the chaotic behavior is short-lived or when working with a relatively short-duration time series or small sets of time-series data. A variety of examples are used to demonstrate the capabilities of PECCARY. These include mathematical examples (sine waves, varieties of noise, well-known chaotic functions), a double pendulum system, and astrophysical tracer particle simulations with potentials of varying intricacies. Since the adopted timescale used to diagnose a given time series can affect the outcome, a method is presented to identify an ideal sampling scheme, constrained by the overall duration and the natural timescale of the system. The accompanying PECCARY Python package and its usage are discussed.}, archive = {J_ApJ}, author = {Sóley Ó. Hyman and Kathryne J. Daniel and David A. Schaffner}, doi = {10.3847/1538-4357/adda3e}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {195}, shortjournal = {The Astrophys. J.}, title = {PECCARY: A novel approach for characterizing orbital complexity, stochasticity, and regularity}, volume = {987}, year = {2025}, }
• (2025). COOL-LAMPS. VIII. known wide-separation lensed quasars and their host galaxies reveal a lack of evolution in MBH/M⋆ since z ∼ 3. ApJ, 987(2), 194. (www)

  @article{ , abstract = {Wide-separation lensed quasars (WSLQs) are a rare class of strongly lensed quasars, magnified by foreground massive galaxy clusters, with typically large magnifications of the multiple quasar images. They are a relatively unexplored opportunity for detailed study of quasar host galaxies. The current small sample of known WSLQs has a median redshift of z ≈ 2.1, larger than most other samples of quasar host galaxies studied to date. Here, we derive precise constraints on the properties of six WSLQs and their host galaxies, using parametric surface brightness fitting, measurements of quasar emission lines, and stellar population synthesis of host galaxies in six WSLQ systems. Our results, with significant uncertainty, indicate that these six hosts are a mixture of star-forming and quiescent galaxies. To probe for coevolution between active galactic nuclei (AGNs) and host galaxies, we model the offset from the “local” ( z = 0) M BH – M ⋆ relation as a simple power law in redshift. Accounting for selection effects, a WSLQ-based model for evolution in the M BH – M ⋆ relation has a power-law index of γ M = −0.42 ± 0.31, consistent with no evolution. Compared to several literature samples, which mostly probe unlensed quasars at z < 2, the WSLQ sample shows less evolution from the local relation, at ∼4 σ . We find that selection effects and choices of M BH calibration are the most important systematics in these comparisons. Given that we resolve host galaxy flux confidently even from the ground in some instances, our work demonstrates that WSLQs and highly magnified AGNs are exceptional systems for future AGN–host coevolution studies.}, archive = {J_ApJ}, author = {Aidan P. Cloonan and Gourav Khullar and Kate A. Napier and Michael D. Gladders and Håkon Dahle and Riley Rosener and Jamar Sullivan and Matthew B. Bayliss and Nathalie Chicoine and Isaiah Escapa and Diego Garza and Josh Garza and Rowen Glusman and Katya Gozman and Gabriela Horwath and Andi Kisare and Benjamin C. Levine and Olina Liang and Natalie Malagon and Michael N. Martinez and Alexandra Masegian and Owen S. Matthews Acuña and Simon D. Mork and Kunwanhui Niu and M. Riley Owens and Yue Pan and Jane R. Rigby and Keren Sharon and Isaac Sierra and Antony A. Stark and Ezra Sukay and Marie Tagliavia and Marcos Tamargo-Arizmendi and Kiyan Tavangar and Raul Teixeira and Kabelo Tsiane and Ruoyang Tu and Grace Wagner and Erik A. Zaborowski and Yunchong Zhang and Yifan “Megan” Zhao}, doi = {10.3847/1538-4357/addabf}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {194}, shortjournal = {The Astrophys. J.}, title = {COOL-LAMPS. VIII. known wide-separation lensed quasars and their host galaxies reveal a lack of evolution in MBH/M⋆ since z ∼ 3}, volume = {987}, year = {2025}, }
• (2025). Recurrent jetlets associated with the disappearance of a satellite spot. ApJ, 987(2), 193. (www)

  @article{ , abstract = {Recurrent small-scale eruptions are fascinating phenomena in the solar atmosphere, characterized by repeated energy buildup and release over short time intervals. However, their underlying physical mechanisms remain unclear. On 2021 May 23, five recurrent jetlets (J1-J5) were observed continuously ejecting from a satellite spot located at the north edge of AR 12824. Using high-resolution, multiwavelength data from NVST, Solar Dynamics Observatory, and IRIS, we investigate the physical characteristics of these jetlets and their relationship with the satellite spot. The widths of these jetlets range from 1300 to 2900 km, their lifetimes range span 3–10 minutes, and their projection speeds vary from 152.8 to 406.0 km s −1 . During the eruptions, the satellite spot moved northwest at a low speed of 376 ± 12 m s −1 . Its area gradually decreased due to magnetic cancellation with the surrounding positive magnetic field, resulting in an average cancellation rate of 1.3 × 10 18 Mx hr −1 . Dark lanes that separated from the satellite spot and small pores were observed to move toward nearby these features or dark lanes with opposite polarities, eventually disappearing during the magnetic cancellation process. J4 was driven by an eruption of a microfilament. Spectral observations revealed a redshift on the right side of J4 and a blueshift on the left side of its base, suggesting a counterclockwise rotation. The horizontal magnetic field of the satellite spot consistently exhibited a vortex structure throughout its evolution until it vanished. The nonlinear force-free field extrapolation confirms that the satellite spot serves as one footpoint of a mini-flux rope. These observations reveal that these jetlets might result from three-dimensional null-point magnetic reconnection, initiated by the continuous eruption of a mini-flux rope or multiple mini-flux ropes, driven by sustained magnetic cancellation.}, archive = {J_ApJ}, author = {Liheng Yang and Xiaoli Yan and Jun Zhang and Zhike Xue and Zhe Xu and Jincheng Wang and Yijun Hou and Yian Zhou and Defang Kong and Roslan Umar and Xinsheng Zhang and Qiaoling Li and Liping Yang}, doi = {10.3847/1538-4357/addac1}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {193}, shortjournal = {The Astrophys. J.}, title = {Recurrent jetlets associated with the disappearance of a satellite spot}, volume = {987}, year = {2025}, }
• (2025). A numerical model for the dynamics of pickup ions outside the heliopause and IBEX “Ribbon” observation. ApJ, 987(2), 192. (www)

  @article{ , abstract = {The leading mechanism for the origin of the Interstellar Boundary Explorer (IBEX) “ribbon” of enhanced energetic neutral atoms (ENAs) from the outer heliosphere is the so-called secondary ENA process. In this mechanism, neutralized ions escape the heliosphere, and after several times of charge exchange collision,s some propagate back toward Earth in directions nearly perpendicular to the local interstellar magnetic field. However, the physical processes governing the distribution of the pickup ions (PUIs) outside the heliopause are still unclear. In this study, we build a new global model of the IBEX ribbon, where a key component is to calculate the dynamics of the PUIs outside the heliopause by solving the gyrophase-averaged focused transport equations on top of the background magnetohydrodynamic-kinetic model for the heliosphere-interstellar medium interaction. We discuss how the properties of the simulated ribbon change with different scattering parameters and show simulation results of the ENA sky maps, ribbon centers, ribbon profiles at several azimuthal slices, the ribbon ENA source region, and the velocity distribution of PUIs in the ENA source region for different scattering frequencies. Our results show that the model can provide reasonable ribbon sky maps comparable to the observed ribbon when the PUI mean free path is on the order of several thousand astronomical units.}, archive = {J_ApJ}, author = {Yifan Huang and Fan Guo and Eric J. Zirnstein and Sung Jun Noh and Hui Li and Daniel B. Reisenfeld and Jacob Heerikhuisen}, doi = {10.3847/1538-4357/addbe3}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {192}, shortjournal = {The Astrophys. J.}, title = {A numerical model for the dynamics of pickup ions outside the heliopause and IBEX “Ribbon” observation}, volume = {987}, year = {2025}, }
• (2025). PKS j0805-0111: A second owens valley radio observatory blazar showing highly significant sinusoidal radio Variability—The tip of the iceberg. ApJ, 987(2), 191. (www)

  @article{ , abstract = {Owens Valley Radio Observatory observations of the supermassive black hole binary (SMBHB) candidate PKS 2131−021 revealed, for the first time, six likely characteristics of the phenomenology exhibited by SMBHBs in blazars, of which the most unexpected and critical is sinusoidal flux density variations. We have now identified a second blazar, PKS J0805−0111, showing similar variations, with a period of 1.422 ± 0.005 yr in the rest frame of the z = 1.388 object. PKS J0805−0111 displays five of the six characteristics observed in PKS 2131−021. To estimate the significance of the sinusoidal variations, we generate 10 6 simulated light curves that reproduce the radio variability characteristics of PKS J0805−0111 and show that the global probability that the periodicity we detect is due to the red-noise tail of the power spectral density is p = 6.7 × 10 −5 (3.82 σ ). This shows that PKS 2131−021 is not a unique case. The discovery of these two objects in a sample of 1158 blazars allows us to reject, at a p -value ∼0.003, the null hypothesis that the sinusoidal variations in these two blazars are all due to a red-noise process. We estimate that the number of SMBHB candidates among blazars is ∼1 in 100.}, archive = {J_ApJ}, author = {P. V. de la Parra and S. Kiehlmann and P. Mróz and A. C. S. Readhead and A. Synani and M. C. Begelman and R. D. Blandford and Y. Ding and F. Harrison and I. Liodakis and W. Max-Moerbeck and V. Pavlidou and R. Reeves and M. Vallisneri and M. F. Aller and M. J. Graham and T. Hovatta and C. R. Lawrence and T. J. W. Lazio and A. A. Mahabal and B. Molina and S. O’Neill and T. J. Pearson and V. Ravi and K. Tassis and J. A. Zensus}, doi = {10.3847/1538-4357/addc60}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {191}, shortjournal = {The Astrophys. J.}, title = {PKS j0805-0111: A second owens valley radio observatory blazar showing highly significant sinusoidal radio Variability—The tip of the iceberg}, volume = {987}, year = {2025}, }
• (2025). Cryogenic differential calorimetry: Exothermicity of amorphous-to-crystalline phase transitions (ACPT) in astrophysical and cometary ice analogs. ApJ, 987(2), 190. (www)

  @article{ , abstract = {Amorphous ice is understood to be the predominant phase of water in cometary nuclei. A significant number of other volatiles can be trapped in amorphous H 2 O ice and released during the amorphous-to-crystalline phase transition (ACPT). This phase transition is an exothermic and is considered a potential cause of cometary outbursts, such as those observed in Comet 1P/Halley and Comet Hale–Bopp. However, only a single experimental study reported in the literature suggests that the presence of impurities (>2%) in amorphous H 2 O ice suppresses the exothermic effect and results in an endothermic phase transition, which contradicts the hypothesis of exothermic-phase-transition-driven comet outbursts. To further explore this phenomenon, we conducted experiments on pure H 2 O, CO:H 2 O, and CO 2 :H 2 O ice mixtures with varying fractions (11%, 50%, and 80% CO, and 11%, 25%, and 50% CO 2 , both relative to H 2 O (100%)). Our experimental setup is a highly sensitive cryogenic differential scanning calorimeter with a μ K noise floor and fifth-decimal resolution in temperature ratio of reference and ice. Our calorimetric data have been internally calibrated to ice sublimation endotherm to derive quantitative calorimetric data. We find that ACPT is exothermic in all CO:H 2 O mixtures and CO 2 :H 2 O mixtures with lower CO 2 fractions. In mixtures with the highest CO 2 content (50% relative to H 2 O (100%)) examined, the ACPT exotherm is weakened. Our results demonstrate that ACPT exothermicity persists throughout the CO and CO 2 mixing ratios observed in a majority of comets, and it should play an important role in comet outbursts when CO and CO 2 are the major volatiles trapped in amorphous H 2 O ice.}, archive = {J_ApJ}, author = {Rahul K. Kushwaha and Murthy S. Gudipati and Bryana L. Henderson}, doi = {10.3847/1538-4357/addc68}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {190}, shortjournal = {The Astrophys. J.}, title = {Cryogenic differential calorimetry: Exothermicity of amorphous-to-crystalline phase transitions (ACPT) in astrophysical and cometary ice analogs}, volume = {987}, year = {2025}, }
• (2025). The burstiness of star formation at z ∼ 6: A huge diversity in the recent star formation histories of very UV-faint galaxies. ApJ, 987(2), 189. (www)

  @article{ , abstract = {IRAC data have long implied that early ( z ≳ 6) galaxies often have very high specific star formation rates (sSFRs ≳ 30 Gyr −1 ), but JWST data have shown that at least some early galaxies are forming stars far less vigorously. Here, we systematically analyze the recent star formation histories (SFHs) of a large ( N = 368) sample of z ∼ 6 Lyman-break galaxies (LBGs) spanning −22 ≲ M UV ≲ −16 assembled from Advanced Camera for Surveys+NIRCam imaging in the GOODS and A2744 fields. We find that very low H α -to-UV luminosity ratios ( L H α / L UV ) and strong recent downturns in star formation rate (SFR) are ≈5× more common among the UV-faintest subset of our sample (〈 M UV 〉 = −17.4) compared to the brightest subset (〈 M UV 〉 = −20.0). The frequency of high L H α / L UV and strong recent SFR upturns is approximately constant with UV luminosity. We discuss how bursty SFHs naturally reproduce this much greater diversity in recent SFHs among very UV-faint galaxies. Using public NIRSpec/prism data, we newly confirm recent strong SFR downturns among three LBGs in our sample, and validate our photometric inferences on key SFH signatures among z ∼ 6 LBGs in general. Our results imply that early galaxies frequently cycle through phases of rapid stellar mass assembly and other periods of much slower growth. This yields huge (≳1–2 mag) fluctuations in M UV on rapid (∼10–30 Myr) timescales, helping explain the surprising abundance of z > 10 galaxies. Finally, we caution that this burstiness causes all existing high-redshift samples (particularly line-selected samples) to be far less complete to galaxies with long recent phases of low sSFR compared to those currently undergoing a burst.}, archive = {J_ApJ}, author = {Ryan Endsley and John Chisholm and Daniel P. Stark and Michael W. Topping and Lily Whitler}, doi = {10.3847/1538-4357/addc74}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {189}, shortjournal = {The Astrophys. J.}, title = {The burstiness of star formation at z ∼ 6: A huge diversity in the recent star formation histories of very UV-faint galaxies}, volume = {987}, year = {2025}, }
• (2025). Accretion of active galactic nucleus stars under the influence of disk geometry. ApJ, 987(2), 188. (www)

  @article{ , abstract = {Massive stars can form within or be captured by active galactic nucleus disks, influencing both the thermal structure and metallicity of the disk environment. In a previous work, we investigated isotropic accretion onto massive stars from a gas-rich, high-entropy background. Here, we consider a more realistic scenario, by incorporating the stratified geometry of the background disk in our 3D radiation hydrodynamic simulations. We find that the accretion remains relatively isotropic when the disk is hot enough and the scale height is thicker than the accretion flow’s nominal supersonic critical radius R crit (subthermal). However, when the disk becomes cold, the accretion flow becomes significantly anisotropic (superthermal). Escaping stellar and accretion luminosity can drive super-Eddington outflows in the polar region, while rapid accretion is sustained along the midplane. Eventually, the effective cross section is constrained by the Hill radius and the disk scale height rather than the critical radius when the disk is cold enough. For our setup (stellar mass ∼50 M ⊙ and background density ρ ∼ 10 −10 g cm −3 ), the accretion rate is capped below ∼0.02 M ⊙ yr −1 and the effective accretion parameter α ∼ 10 −1 over the disk temperature range 3–7 × 10 4 K. Spiral arms facilitate inward mass flux by driving outward angular momentum transport. Gap-opening effects may further reduce the long-term accretion rate, although to confirm this would require global simulations evolved over much longer viscous timescales.}, archive = {J_ApJ}, author = {Yi-Xian Chen and Yan-Fei Jiang and Jeremy Goodman}, doi = {10.3847/1538-4357/addd0a}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {188}, shortjournal = {The Astrophys. J.}, title = {Accretion of active galactic nucleus stars under the influence of disk geometry}, volume = {987}, year = {2025}, }
• (2025). Thermophysical properties of lunar regolith revealed by thermal-infrared observations of the lunar reconnaissance orbiter (LRO) diviner radiometer. ApJ, 987(2), 187. (www)

  @article{ , abstract = {The thermophysical properties of lunar regolith are crucial for lunar sciences and engineering. Here, we evaluate the thermophysical properties of lunar regolith between 75°N and 75°S from Diviner data by treating the radius of lunar regolith grains as a proxy. By the ground-truth median/average grain radius and Diviner data at several lunar landing sites, we recalibrate the reference rolling force for a grain radius of 0.475 μ m as 0.9 ± 0.1 × 10 −7 N. On a global scale, the estimated grain radius values focus mostly between 40 and 60 μ m and show an average value of ∼55.3 μ m. Some regions of Oceanus Procellarum, Mare Imbrium, and Mare Frigoris show abnormally large grain radius 80–100 μ m, which are associated with the late high-Ti volcanism during 2.3–1.2 Ga within Procellarum KREEP Terrane. Mare Humorum is dated to be as old as 3.9 Ga, but still shows large grain radius values of ∼100 μ m that are far greater than those in other contemporaneous mares. Such an anomaly may indicate a distinguished evolution for the local lunar regolith. For the surficial lunar regolith on the global scale, the contact component of thermal conductivity normalized to a temperature of 250 K varies mostly within 0.0008–0.0014 W (m K) −1 , whereas the radiative component normalized to 250 K varies mostly within 0.002–0.004 W (m K) −1 . The thickness of the topmost loosely packed layer is estimated as 0.02–0.07 m and tends to increase with the evolution of lunar regolith, which relates to the modification of packing style with the decrease of grain radius.}, archive = {J_ApJ}, author = {Shuoran Yu and Minjun Yu and Xiao Xiao and Jun Huang and Long Xiao}, doi = {10.3847/1538-4357/addd1d}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {187}, shortjournal = {The Astrophys. J.}, title = {Thermophysical properties of lunar regolith revealed by thermal-infrared observations of the lunar reconnaissance orbiter (LRO) diviner radiometer}, volume = {987}, year = {2025}, }
• (2025). Medium-band astrophysics with the grism of NIRCam in frontier fields (MAGNIF): Spectroscopic census of hα luminosity functions and cosmic star formation at z ∼ 4.5 and 6.3. ApJ, 987(2), 186. (www)

  @article{ , abstract = {We measure H α luminosity functions (LFs) at redshifts z ∼ 4.5 and 6.3 using the JWST Medium-band Astrophysics with the Grism of NIRCam In Frontier fields (MAGNIF) survey. MAGNIF obtained NIRCam grism spectra with the F360M and F480M filters in four Frontier Fields. We identify 248 H α emitters based on the grism spectra and photometric redshifts from combined Hubble Space Telescope and JWST imaging data. The numbers of the H α emitters show a large field-to-field variation, highlighting the necessity of multiple fields to mitigate cosmic variance. We calculate observed and dust-corrected H α LFs at the two redshifts. Thanks to the gravitational lensing, the measured H α LFs span three orders of magnitude in luminosity, and the faint-end luminosity reaches L H α ∼ 10 40.3 erg s −1 at z ∼ 4.5 and 10 41.5 erg s −1 at z ∼ 6.3. They correspond to star formation rates of ∼0.1 and 1.7 M ⊙ yr −1 , respectively. We conclude no or weak redshift evolution of the faint-end slope of H α LF across z ≃ 0.4–6.3, and the comparison with the faint-end slopes of UV LF indicates stochastic star formation history among low-mass H α emitters. The derived cosmic star formation rate densities are 0.05{8}_{-0.006}^{+0.008}\,{M}_{\odot }\,{\mathrm{yr}}^{-1}\,{\mathrm{Mpc}}^{-3} at z ∼ 4.5 and 0.02{5}_{-0.007}^{+0.009}\,{M}_{\odot }\,{\mathrm{yr}}^{-1}\,{\mathrm{Mpc}}^{-3} at z ∼ 6.3. These are approximately 2.2 times higher than previous estimates based on dust-corrected UV LFs, but consistent with recent measurements from infrared surveys. We discuss uncertainties in the H α LF measurements, including those propagated from the lens models, cosmic variance, and active galactic nucleus contribution, and we find that they have a negligible impact on the above results.}, archive = {J_ApJ}, author = {Shuqi Fu and Fengwu Sun and Linhua Jiang and Xiaojing Lin and Jose M. Diego and Lukas J. Furtak and Mathilde Jauzac and Anton M. Koekemoer and Mingyu Li and Masamune Oguri and Nency R. Patel and Christopher N. A. Willmer and Rogier A. Windhorst and Adi Zitrin and Franz E. Bauer’s and Chian-Chou Chen and Wenlei Chen and Cheng Cheng and Christopher J. Conselice and Daniel J. Eisenstein and Eiichi Egami and Daniel Espada and Xiaohui Fan and Seiji Fujimoto and Tiger Yu-Yang Hsiao and Xiangyu Jin and Kotaro Kohno and David J. Lagattuta and Zihao Li and Weizhe Liu and Jordi Miralda-Escudé and Yuanhang Ning and Sandro Tacchella and Wei Leong Tee and Hideki Umehata and Feige Wang and Haojing Yan and Yongda Zhu}, doi = {10.3847/1538-4357/adddb1}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {186}, shortjournal = {The Astrophys. J.}, title = {Medium-band astrophysics with the grism of NIRCam in frontier fields (MAGNIF): Spectroscopic census of hα luminosity functions and cosmic star formation at z ∼ 4.5 and 6.3}, volume = {987}, year = {2025}, }
• (2025). How do massive primordial black holes impact the formation of the first stars and galaxies?. ApJ, 987(2), 185. (www)

  @article{ , abstract = {We investigate the impact of massive primordial black holes (PBHs; m BH ∼ 10 6 M ⊙ ) on the star formation and first galaxy assembly process using high-resolution hydrodynamical simulations from z = 1100 to z ∼ 9. We find that PBH accretion is self-regulated by feedback, suppressing mass growth unless feedback is weak. PBHs accelerate structure formation by seeding dark matter (DM) halos and gravitationally attracting gas, but strong feedback can delay cooling and suppress star formation. In addition, the presence of baryon-DM streaming creates an offset between the PBH location and the peaks induced in gas density, promoting earlier and more efficient star formation compared to standard ΛCDM. By z ∼ 10, PBH-seeded galaxies form dense star clusters, with PBH-to-stellar mass ratios comparable to observed high- z active galactic nuclei like UHZ-1. Our results support PBHs as viable supermassive black hole (SMBH) seeds but do not exclude alternative scenarios. We emphasize that PBH-seeding provides a natural explanation for some of the newly discovered overmassive SMBHs at high redshift, in particular those with extreme ratios of BH-to-dynamical (virial) mass that challenge standard formation channels. Future studies with ultra-deep JWST surveys, the Roman Space Telescope, and radio surveys with facilities such as the Square Kilometre Array and Hydrogen Epoch of Reionization Array will be critical in distinguishing PBH-driven SMBH growth from other pathways.}, archive = {J_ApJ}, author = {Saiyang Zhang and Boyuan Liu and Volker Bromm and Junehyoung Jeon and Michael Boylan-Kolchin and Florian Kühnel}, doi = {10.3847/1538-4357/adddb4}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {185}, shortjournal = {The Astrophys. J.}, title = {How do massive primordial black holes impact the formation of the first stars and galaxies?}, volume = {987}, year = {2025}, }
• (2025). Population models for star formation timescales in early galaxies: The first step toward solving outshining in star formation history inference. ApJ, 987(2), 184. (www)

  @article{ , abstract = {James Webb Space Telescope (JWST) has revealed temporarily quenched and ultraviolet-luminous galaxies in the early Universe, suggesting enhanced star formation stochasticity. Verifying this hypothesis is critical yet challenging. Outshining, wherein light from young stars dominates the spectral energy distribution, represents perhaps the greatest challenge in inferring the formation histories of unresolved galaxies. In this paper, we take a simple model of burstiness and show that state-of-the-art inference methods with flexible star formation histories (SFHs) and neutral priors, while recovering average star formation rates (SFRs; ∼0.1 dex median offset), fail to recover the complexities of fluctuations on tens of Myr timescales, and typically underestimate masses in bursty systems (∼0.15 dex). Surprisingly, detailed SFH recovery is still sensitive to priors even when data quality is optimal, e.g., including high signal-to-noise (20 pixel −1 ) spectroscopy with wide coverage (rest-frame 0.12–1.06 μ m). Crucially, however, refitting the same data with a prior correctly encoding the bursty expectation eliminates these biases: median offsets in mass and SFRs decrease to ∼0.04 dex and ∼0.05 dex, respectively. Under the assumption that current population burstiness predicts past SFH, the solution to outshining in modeling statistical samples is empirically measuring recent galaxy SFHs with population modeling. A prototype is H α /UV: while helpful, it is insufficient to constrain the expected complex burstiness. To this end, we introduce a more complete, quantitative population-level approach and demonstrate that it promises to recover the typical amplitude, timescale, and slope of the recent SFH to high accuracy. This approach thus has the strong potential to solve outshining using observations from JWST.}, archive = {J_ApJ}, author = {Bingjie Wang and Joel Leja and Hakim Atek and Rachel Bezanson and Emilie Burnham and Pratika Dayal and Robert Feldmann and Jenny E. Greene and Benjamin D. Johnson and Ivo Labbé and Michael V. Maseda and Themiya Nanayakkara and Sedona H. Price and Katherine A. Suess and John R. Weaver and Katherine E. Whitaker}, doi = {10.3847/1538-4357/adddb8}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {184}, shortjournal = {The Astrophys. J.}, title = {Population models for star formation timescales in early galaxies: The first step toward solving outshining in star formation history inference}, volume = {987}, year = {2025}, }
• (2025). The coronal plasma density structure over a solar cycle: A comparison of tomography and magnetohydrodynamic simulations. ApJ, 987(2), 183. (www)

  @article{ , abstract = {The large-scale plasma density structure of the extended solar corona is a tracer of the underlying magnetic field configuration and dictates the structure of the solar wind in interplanetary space. Accurate density maps are therefore important to probe the physics of the solar corona and the solar wind, and to improve space-weather forecasting. Density can be estimated from coronagraph observations using solar rotational tomography and is independently provided by global magnetohydrodynamic models. This study compares densities from tomography with the Magnetohydrodynamic Algorithm outside a Sphere (MAS) model across the whole corona over a solar cycle from 2007 to late 2023. The dependence of electron densities on latitude and heliocentric height is compared, with densities in better agreement at equatorial regions and lower heights. The streamer and nonstreamer regions are compared separately, as well as the average width of the streamer belt over the duration of solar cycle 24. The MAS model densities contain more fine-scale detail than those of the tomography, but there is a very good overall agreement in the structure and location of high-density features. In polar regions, where the photospheric magnetic field measurements that drive the MAS simulations present very large uncertainties, the tomographic densities are more accurate. Investigating the accuracy and reliability of these models, and understanding their limitations is crucial. Comparisons with observations highlight their advantages and disadvantages while stressing the importance of observational techniques to help constrain current and future models.}, archive = {J_ApJ}, author = {Liam T. Edwards and Huw Morgan and Pete Riley and Jon A. Linker}, doi = {10.3847/1538-4357/adddba}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {183}, shortjournal = {The Astrophys. J.}, title = {The coronal plasma density structure over a solar cycle: A comparison of tomography and magnetohydrodynamic simulations}, volume = {987}, year = {2025}, }
• (2025). The impact of physical processes on the radial evolution of the distant pickup ion mediated solar wind. ApJ, 987(2), 182. (www)

  @article{ , abstract = {H + pickup ions (PUIs), formed through charge exchange between solar wind (SW) protons and interstellar neutral hydrogen (ISN H) atoms or by the photoionization of ISN H atoms, play a key role in governing SW dynamics. These PUIs induce MHD waves by generating instabilities, driving turbulence in the outer heliosphere. The ionization cavity size is the distance at which the ISN H density becomes e −1 , which is smaller in the upwind direction than in the downwind direction. Consequently, the turbulent shear source affects the SW over a larger distance in the downwind direction than in the upwind direction. Here, we integrate the continuity, momentum, and pressure equations for ISN H with the three fluid (protons, electrons, and H + PUIs) equations and the turbulence transport equations. We numerically solve the coupled four-fluid and turbulence transport equations between 10 and 68 au, and 10 and 115 au, before the heliospheric termination shock in the New Horizons (NH) and Pioneer 10 (P10) directions, respectively. We present the comparison of the theoretical results with the SW proton and PUI data of NH and the SW proton data of P10. We present the theoretical results of the low-frequency MHD turbulence and the cosmic-ray mean free paths along these directions. Finally, we derive the equation for the scattering angle of radio waves by assuming isotropic and Gaussian density turbulence and calculate the scattering angle in the NH and P10 directions.}, archive = {J_ApJ}, author = {Laxman Adhikari and Gary P. Zank and Bishwas L. Shrestha and Samira Tasnim and Lingling Zhao and Heather Elliott and Merav Opher and Bingbing Wang and Jakobus Le Roux and Alexander Pitňa and David J. McComas and Parisa Mostafavi and John Richardson and Xingyu Zhu and Yihong Wu and Justyna M. Sokół and Romina Nikoukar}, doi = {10.3847/1538-4357/adde4f}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {182}, shortjournal = {The Astrophys. J.}, title = {The impact of physical processes on the radial evolution of the distant pickup ion mediated solar wind}, volume = {987}, year = {2025}, }
• (2025). Modeling asteroseismic yields for the roman galactic bulge time-domain survey. ApJ, 987(2), 181. (www)

  @article{ , abstract = {The Galactic Bulge Time-Domain Survey (GBTDS) of the Roman Space Telescope will take high-cadence data of the Galactic bulge. We investigate the asteroseismic potential of this survey for red giants. We simulate the detectability of global asteroseismic frequencies, {\nu }_{{\rm{\max }}} and Δ ν , by modifying Kepler data to match nominal GBTDS observing strategies, considering different noise models, observing cadences, and detection algorithms. Our baseline case, using conservative assumptions, consistently leads to asteroseismic {\nu }_{{\rm{\max }}} detection probabilities above 80% for red clump and red giant branch (RGB) stars brighter than the 16th magnitude in Roman’s F146 filter. We then inject these detection probabilities into a Galaxia model of the bulge to estimate asteroseismic yields. For our nominal case, we detect 290,000 stars in total, with 185,000 detections in the bulge. Different assumptions give bulge yields from 135,000 to 349,000 stars. For stars with measured {\nu }_{{\rm{\max }}} , we find that we can recover Δ ν in 21%–42% of red clump stars, and 69%–92% of RGB stars. The expected yield and stellar parameter precision we predict for Roman asteroseismology promise to characterize planet-hosting stellar populations and to resolve questions regarding the formation history of the bulge.}, archive = {J_ApJ}, author = {Trevor J. Weiss and Noah J. Downing and Marc H. Pinsonneault and Joel C. Zinn and Dennis Stello and Timothy R. Bedding and Kaili Cao and Marc Hon and Claudia Reyes and B. Scott Gaudi and Robert F. Wilson and Daniel Huber and Sanjib Sharma}, doi = {10.3847/1538-4357/adde5b}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {181}, shortjournal = {The Astrophys. J.}, title = {Modeling asteroseismic yields for the roman galactic bulge time-domain survey}, volume = {987}, year = {2025}, }
• (2025). NuSTAR observations of GS 1826-238 in the extended soft state. ApJ, 987(2), 180. (www)

  @article{ , abstract = {We report on the first focused NuSTAR observations of the neutron star low mass X-ray binary GS 1826-238, the “Clocked Burster,” since the extended soft state began in 2014. Throughout this day-long observation, we see spectral variability that is consistent with the “banana” branch of atoll LMXBs. The NuSTAR hard X-ray spectrum is consistent with that seen during the initial soft-state excursion in 2014 and is modeled as a double Comptonized plasma: one with low temperature and high optical depth, the other with high temperature and low optical depth. The spectral variations that we see in this source are mostly consistent with variations in the optical depth of the hot component, though the total flux from the source remains nearly constant. A single Type I X-ray burst is seen during this observation, which has a short main peak (timescales of seconds) followed by an extended tail of emission. The shape of this burst is not consistent with a PRE and provide diagnostic information on the regions of the NS surface supplying the fuel for the thermonuclear reaction.}, archive = {J_ApJ}, author = {B. W. Grefenstette and M. C. Brumback and D. J. K. Buisson and R. M. Ludlam and G Mastroserio and S. N. Pike and J. A. Tomsick and S. B. Yun}, doi = {10.3847/1538-4357/addf3f}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {180}, shortjournal = {The Astrophys. J.}, title = {NuSTAR observations of GS 1826-238 in the extended soft state}, volume = {987}, year = {2025}, }
• (2025). Comparison of empirical and deep learning models for solar wind speed prediction. ApJ, 987(2), 179. (www)

  @article{ , abstract = {In this study, we compare representative empirical models with a deep learning model for predicting solar wind speed at 1 au. The empirical models are the Wang–Sheeley–Arge–ENLIL model, which combines empirical methods with a magnetohydrodynamic model, and the empirical solar wind forecast model, which uses the relationship between the fractional coronal hole area and solar wind speed. Our deep learning model predicts solar wind speed over 3 days ahead using extreme-ultraviolet images and up to 5 days of solar wind speed before the prediction date. We evaluate the models over the test period (October–December in each year from 2012 to 2020) in view of solar activity phases and the entire period. To validate the model’s performance, we use two evaluation methods: a statistical approach and an event-based approach. For statistical verification during the entire period, our model outperforms the other empirical models, with a much lower mean absolute error of 51.4 km s −1 and rms error of 68.6 km s −1 , along with a much higher correlation coefficient of 0.69. For the event-based verification for high-speed solar wind streams, our model has superior performance in most of the six metrics evaluated within a ±1 day time window. In particular, it achieves a high success ratio of 0.82, emphasizing the model’s stable performance and ability to minimize false alarms. These results show that our deep learning model has strong potential for practical application as a reliable tool for fast solar wind forecasting with its high accuracy and stability.}, archive = {J_ApJ}, author = {Seungwoo Ahn and Jihyeon Son and Yong-Jae Moon and Hyun-Jin Jeong}, doi = {10.3847/1538-4357/ade0b4}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {179}, shortjournal = {The Astrophys. J.}, title = {Comparison of empirical and deep learning models for solar wind speed prediction}, volume = {987}, year = {2025}, }
• (2025). The nonthermal emission following GW170817 is consistent with a conical radially stratified outflow with initial lorentz factor ≲10. ApJ, 987(2), 178. (www)

  @article{ , abstract = {We show that the nonthermal radio to X-ray emission following the neutron star merger GW170817 is consistent with synchrotron emission from a collisionless shock driven into the interstellar medium (ISM) by a conical radially stratified outflow observed ≈0.25 rad off-axis, with a power-law mass dependence on momentum, M (> γβ ) ∝ ( γβ ) −4 , maximum Lorenz factor γ = 10, opening (half-)angle ≈0.15 rad, and total energy of ≈5 × 10 50 erg. The temporal dependence of the flux during its rising phase is determined by the radial stratification structure, which determines the rate at which outflow energy is deposited in the ISM. This is in contrast with highly relativistic, γ ≈ 100, structured jet models, where the angular jet structure determines the time dependence through the gradual “unveiling” by deceleration of larger angular sections of the jet (which are initially “hidden” by relativistic beaming), typically leading to a predicted flux decline after the peak that is faster than observed. Our model predicts a dependence on the observing angle, which is different than that predicted by highly relativistic jet models. Particularly, similar merger events observed closer to the symmetry axis are predicted to show a similarly extended duration of flux increase with time. Our analysis demonstrates that the data do not require a highly relativistic γ ≈ 100 component, but the presence of such a component with opening angle ≪0.15 rad and energy ≪5 × 10 50 erg cannot be excluded.}, archive = {J_ApJ}, author = {Gilad Sadeh and Eli Waxman}, doi = {10.3847/1538-4357/ade150}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {178}, shortjournal = {The Astrophys. J.}, title = {The nonthermal emission following GW170817 is consistent with a conical radially stratified outflow with initial lorentz factor ≲10}, volume = {987}, year = {2025}, }
• (2025). The moon as a cosmic-ray spectrometer: Prospects for MeV gamma-ray observations. ApJ, 987(2), 177. (www)

  @article{ , abstract = {The Moon is the closest celestial gamma-ray emitting object. Its gamma-ray emission arises from interactions between Galactic cosmic rays (CRs) and the lunar surface. While the lunar GeV gamma-ray spectrum is dominated by a continuum from hadronic decay processes, the MeV emission exhibits both continuum and distinctive spectral lines from nuclear de-excitation and radioactive decay processes. Using Geant4 Monte Carlo particle simulations, we model the lunar gamma-ray spectrum. Our results demonstrate its consistency with Fermi-Large Area Telescope observations, and predict that next-generation MeV gamma-ray instruments will detect both the lunar MeV continuum and several key spectral line features, notably the 1.779 MeV line from 28 Si de-excitation enhanced by the lunar surface composition, the e + e − annihilation line, and radioactive decay lines from 22 Na ( τ ≈ 3.75 yr) and long-lived 26 Al ( τ ≈ 1 Myr). These gamma-ray lines are sensitive to CRs with energies ≲1 GeV nuc −1 , offering unique temporal probes of CR activity over different timescales. Observations of the lunar MeV gamma-ray spectrum will therefore open a new window to study the current irradiation of the solar-terrestrial environment by low-energy CRs and its long-term temporal evolution.}, archive = {J_ApJ}, author = {Tatsuki Fujiwara and Ellis R. Owen and Yoshiyuki Inoue and Manel Errando and Kohei Fukuda and Kazuhiro Nakazawa and Hirokazu Odaka and Keigo Okuma and Kentaro Terada and Naomi Tsuji and Yasunobu Uchiyama and Hiroki Yoneda and Ao Zhang}, doi = {10.3847/1538-4357/add68b}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {177}, shortjournal = {The Astrophys. J.}, title = {The moon as a cosmic-ray spectrometer: Prospects for MeV gamma-ray observations}, volume = {987}, year = {2025}, }
• (2025). The effects of cuboid particle scattering on reflected light phase curves: Insights from laboratory data and theory. ApJ, 987(2), 176. (www)

  @article{ , abstract = {Understanding the optical properties of exoplanet cloud particles is a top priority. Many cloud condensates form as nonspherical particles and their optical properties can be very different from those of spheres. In this study, we focus on KCl particles, which likely form as cuboids in warm ( T = 500–1000 K) exoplanet atmospheres. We compare the phase functions (at 532 nm wavelength) of KCl particles computed with Mie theory, the two-term Henyey–Greenstein (TTHG) approximation, laboratory data, and the discrete dipole approximation (DDA). Mie theory assumes scattering from spheres, while TTHG functions are used to approximate cloud scattering in two-stream radiative transfer models like PICASO . Laboratory measurements and DDA allow for a robust understanding of scattering from cuboid and deformed cuboid particle shapes. We input these phase functions into PICASO using cloud distributions from the cloud model Virga , to determine how different phase functions can impact the reflected-light intensities of the benchmark sub-Neptune, GJ 1214b. Simulated reflected light phase curves of GJ 1214b produced using the TTHG, laboratory, and DDA phase curves differ by less than 3 ppm. Our findings suggest that TTHG phase functions may be useful for approximating the scattering intensity of certain cuboid and irregular particle shapes. Future work should expand upon the wavelengths and particles considered to better determine when scattering approximations, like TTHG, may be useful in lieu of more accurate, but time-consuming laboratory measurements and/or nonspherical scattering theory.}, archive = {J_ApJ}, author = {Colin D. Hamill and Alexandria V. Johnson and Matt Lodge and Peter Gao and Rowan Nag and Natasha Batalha and Duncan A. Christie and Hannah R. Wakeford}, doi = {10.3847/1538-4357/add7cf}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {176}, shortjournal = {The Astrophys. J.}, title = {The effects of cuboid particle scattering on reflected light phase curves: Insights from laboratory data and theory}, volume = {987}, year = {2025}, }
• (2025). Seismic constraints on the spin evolution of slowly rotating young intermediate-mass stars. ApJ, 987(2), 175. (www)

  @article{ , abstract = {δ Scuti stars are hot, rapid rotators and a poorly understood class of pulsators. Asteroseismology provides the only means with which to probe their interior dynamics. However, their complex and unexplained oscillation patterns restrict analyses to only a small fraction with interpretable pulsations. Here, we identify 5381 δ Scuti stars from 63 sectors of TESS observations, of which 300 had interpretable oscillations, with 24 showing rotational splittings. We inferred compositions and ages ( τ ) for the 300 stars, finding them in near-zero-age-main-sequence (ZAMS) states, and measured the mean envelope rotation rates (〈 f rot 〉) for 24 of them. Analyzing their age-dependent rotation, we found that these stars essentially exhibit weak to no spin-down while evolving past the ZAMS across a narrow time span during which they show regular pulsations. A quantitative fit to their spin evolution results in a trend f rot ( d −1 ) ∝ ( τ /Gyr) −0.048 ± 0.016 , much slower than the spin-down of cooler late-type stars due to magnetic braking (Skumanich’s law: f rot ( d −1 ) ∝ ( τ /Gyr) −0.5 ). Based on stellar evolution calculations, we show that this weak spin-down is consistent with the gradual increase in the moment of inertia.}, archive = {J_ApJ}, author = {Kunal H. Singh and Subrata Kumar Panda and Shravan M. Hanasoge and Siddharth Dhanpal}, doi = {10.3847/1538-4357/add7df}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {175}, shortjournal = {The Astrophys. J.}, title = {Seismic constraints on the spin evolution of slowly rotating young intermediate-mass stars}, volume = {987}, year = {2025}, }
• (2025). Monosilane worlds: Sub-neptunes with atmospheres shaped by reduced magma oceans. ApJ, 987(2), 174. (www)

  @article{ , abstract = {High-precision infrared spectroscopic measurements now enable detailed characterization of sub-Neptune atmospheres, potentially providing constraints on their interiors. Motivated by this, atmospheric models have been developed to explore chemical interactions between hydrogen-dominated atmospheres and possibly underlying magma oceans with various redox states. Recent models have predicted monosilane (SiH 4 ) as a potential atmospheric species derived from magma oceans in sub-Neptunes, but suggested that it is highly depleted in the observable atmospheric layers. Here, we propose that SiH 4 can persist throughout the atmospheres of sub-Neptunes with FeO-free reduced magma oceans by considering the dissolution of H 2 O into the magma oceans, a factor not accounted for in previous models. We construct a one-dimensional atmospheric model to simulate the chemical equilibrium composition of hydrogen-dominated atmospheres overlying FeO-free magma oceans, incorporating H–O–Si chemistry. Our results show that the dissolution of H 2 O enhances the SiH 4 molar fraction to levels of 0.1%–10%, preventing it from reverting to silicates in the upper atmospheric layers. We find that SiH 4 -rich atmospheres can exist across a broad parameter space with ground temperatures of 2000–6000 K and hydrogen pressures of 10 2 –10 5 bar. We discuss that SiH 4 -rich atmospheres could contain the other silanes but lack C-/N-/O-bearing species. The detection of SiH 4 in future observations of sub-Neptunes would provide compelling evidence for the presence of a rocky core with a reduced magma ocean. However, the accuracy of our model is limited by the lack of data on the nonideal behavior and radiative properties of SiH 4 , highlighting the need for further numerical and laboratory investigations.}, archive = {J_ApJ}, author = {Yuichi Ito and Tadahiro Kimura and Kazumasa Ohno and Yuka Fujii and Masahiro Ikoma}, doi = {10.3847/1538-4357/add3fe}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {174}, shortjournal = {The Astrophys. J.}, title = {Monosilane worlds: Sub-neptunes with atmospheres shaped by reduced magma oceans}, volume = {987}, year = {2025}, }
• (2025). Rotation measure jitter: Wavelength-dependent scatter in rotation measure related to faraday complexity. ApJ, 987(2), 173. (www)

  @article{ , abstract = {The relation between Faraday rotation measure (RM) and differential Faraday rotation by unresolved structure of a turbulent plasma is investigated for extragalactic radio sources. The RM scatter of a sample of sources affected by turbulent Faraday screens with identical power spectra of Faraday depth structure is referred to as RM jitter. For fixed amplitude and slope of the power spectrum, the range of possible RMs depends on the wavelength coverage of the survey. RM jitter is independent of Faraday depth resolution as it results from the true Faraday depth dispersion and effects of wavelength-dependent depolarization. RM jitter for a flux-density-limited sample is sensitive to the power-law index γ of the power spectrum of Faraday depth structure. Assuming depolarization by a turbulent Faraday screen for all sources, a simulated flux-density-limited sample can reproduce the high RM scatter found by S. Vanderwoude et al. (2024) for sources that are less than 3% polarized. RM jitter of sources that are more than 3% polarized is found to be smaller than the observed scatter, indicating that plasma other than the near-source environment dominates the RM scatter for the more polarized sources. The significance of RM jitter for applications of the RM grid is discussed.}, archive = {J_ApJ}, author = {Jeroen M. Stil}, doi = {10.3847/1538-4357/add69e}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {173}, shortjournal = {The Astrophys. J.}, title = {Rotation measure jitter: Wavelength-dependent scatter in rotation measure related to faraday complexity}, volume = {987}, year = {2025}, }
• (2025). Absence of a runaway greenhouse limit on lava planets. ApJ, 987(2), 172. (www)

  @article{ , abstract = {Climate transitions on exoplanets offer valuable insights into the atmospheric processes governing planetary habitability. Previous pure-steam atmospheric models show a thermal limit in outgoing long-wave radiation, which has been used to define the inner edge of the classical habitable zone and guide exoplanet surveys aiming to identify and characterize potentially habitable worlds. We expand upon previous modelling by treating (i) the dissolution of volatiles into a magma ocean underneath the atmosphere, (ii) a broader volatile range of the atmospheric composition including H 2 O, CO 2 , CO, H 2 , CH 4 , and N 2 , and (iii) a surface-temperature- and mantle-redox-dependent equilibrium chemistry. We find that multicomponent atmospheres of outgassed composition located above partially or fully molten mantles do not exhibit the characteristic thermal radiation limit that arises from pure-steam models, thereby undermining the canonical concept of a runaway greenhouse limit, and hence challenging the conventional approach of using it to define an irradiation-based habitable zone. Our results show that atmospheric heat loss to space is strongly dependent on the oxidation and melting state of the underlying planetary mantle, through their significant influence on the atmosphere’s equilibrium composition. This suggests an evolutionary hysteresis in climate scenarios: Initially molten and cooling planets do not converge to the same climate regime as solidified planets that heat up by external irradiation. Steady-state models cannot recover evolutionary climate transitions, which instead require self-consistent models of the temporal evolution of the coupled feedback processes between interior and atmosphere over geologic time.}, archive = {J_ApJ}, author = {Iris D. Boer and Harrison Nicholls and Tim Lichtenberg}, doi = {10.3847/1538-4357/add69f}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {172}, shortjournal = {The Astrophys. J.}, title = {Absence of a runaway greenhouse limit on lava planets}, volume = {987}, year = {2025}, }
• (2025). The secular periodic evolution of X-ray quasiperiodic eruptions driven by Star−Disk collisions. ApJ, 987(2), 171. (www)

  @article{ , abstract = {We study the secular periodic evolution of quasiperiodic eruptions (QPEs) for GSN069 and eRO-QPE2 assuming that they are driven by star−disk collisions. We set up numerical simulations and compared them with the observed periodic decay of ∼−3160 ± 720 s yr −1 in GSN069 and ∼−370 ± 40 s yr −1 in eRO-QPE2. We find the following: (1) Stellar-mass black holes are unlikely to be the orbiters in these two sources, as their periodic decays are on the order of <10 s yr −1 . (2) A naked degenerate core (including a white dwarf) is unlikely to be the orbiter in GSN069, as the decay is on the order of <200 s yr −1 . However, it is possible in eRO-QPE2, although the required surface density of the accretion disk is relatively high (e.g., Σ ≳ 10 7 –10 8 g cm −2 ). (3) Both the orbiters in GSN069 and eRO-QPE2 can be solar-like main-sequence (MS) stars. However, each collision can lead to gradual ablation of the stellar envelope on the order of 10 −5 to 10 −3 M ⊙ . To reproduce the observed decay while surviving for ≳3 yr, the surface density of the disk needs to be within a certain range. For example, given a 1 M ⊙ MS orbiter, the surface density of the disk gas should be in the range of 3 × 10 5 g cm −2 to 2 × 10 6 g cm −2 for GSN069 or 5 × 10 4 g cm −2 to 10 6 g cm −2 for eRO-QPE2. In both of these sources, the MS star cannot survive for more than ∼12 yr. We expect that future observations of these two sources can help to distinguish whether the orbiters are degenerated compact objects or gaseous stars.}, archive = {J_ApJ}, author = {Jiajun Xian and Fupeng Zhang and Liming Dou and Zhining Chen}, doi = {10.3847/1538-4357/add72d}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {171}, shortjournal = {The Astrophys. J.}, title = {The secular periodic evolution of X-ray quasiperiodic eruptions driven by Star−Disk collisions}, volume = {987}, year = {2025}, }
• (2025). Searching for radio transients with inverted spectra in epoch 1 of VLASS and VCSS, and identification of a sample of candidate relativistic nuclear transients. ApJ, 987(2), 170. (www)

  @article{ , abstract = {For radio transients, an inverted spectrum (defined as α > 0 for a power-law spectrum S ν ∝ ν α ) constrains physical properties, which in principle can be a useful criterion for selecting specific targets of interest in a transient search. To test and develop this concept, we have searched epoch 1 of the Very Large Array Sky Survey (VLASS; 3.0 GHz) and the VLITE Commensal Sky Survey (VCSS; 340 MHz) for radio transients with inverted spectra. We discover a sample of 21 inverted-spectra transient candidates that are not associated with cataloged active galactic nuclei (AGNs). To the best of our knowledge, three of our candidates have recently been reported by others as radio transients, but none have reported transient counterparts at other wavelengths. We find that our candidates evolve slowly over years and show either highly inverted spectra or peaked spectra over ∼1–3 GHz. Within our sample, nine candidates are matched to optical centers of galaxies and have estimated radio spectral luminosities of L 3.0GHz ∼ 10 30 –10 33 erg s −1 Hz −1 . Based on the observed properties, we find the most plausible transient classification for our candidates to be relativistic tidal disruption events. However, it is difficult to rule out variable or transient AGNs with highly inverted spectra. Upon examining physical constraints, we confirm that mainly relativistic transients (on-axis or off-axis) with equipartition energy E eq ≳ 10 49 –10 53 erg are expected from searching VLASS and VCSS based on inverted spectra. The obtainable physical constraints, however, can be weak due to degeneracy introduced by viewing angle.}, archive = {J_ApJ}, author = {Yuyang Chen and B. M. Gaensler and Tracy Clarke and Wendy Peters and Emil Polisensky and Kovi Rose}, doi = {10.3847/1538-4357/add924}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {170}, shortjournal = {The Astrophys. J.}, title = {Searching for radio transients with inverted spectra in epoch 1 of VLASS and VCSS, and identification of a sample of candidate relativistic nuclear transients}, volume = {987}, year = {2025}, }
• (2025). Unveiling the complex jet dynamics in the blazar 2021+317 through multiepoch very long baseline interferometry observations. ApJ, 987(2), 169. (www)

  @article{ , abstract = {We present an investigation of the compact structure of the active galactic nucleus 2021+317 based on multiepoch very long baseline interferometry (VLBI) observations at 15, 22, and 43 GHz in the period from 2013 through 2024. The VLBI images show a core–jet structure extended to the south, with two stationary components in the northern region, one of which is likely to be the core of the source. We also detected two new moving jet components (S4 and S5) in the observations of 2021. Based on these observational findings, we analyzed two distinctive jet models involving one or another stationary component mentioned above as the jet core. One model assumes a moderate bulk motion velocity, a wider viewing angle, and a lower Doppler factor, with the magnetic field energy density significantly dominating over the nonthermal particle energy density. The other model involves a higher bulk motion velocity, a narrower viewing angle, and a higher Doppler factor, with an even greater dominance of magnetic field energy in the core. The position angle of the jet ridgeline rotates counterclockwise over the observed period. The apparent kinematics of the jet components is more consistent with a model of the precessing jet, which has recently completed the first half of the precession cycle. Our results provide constraints on the dynamic evolution of the jet and its interaction with the surrounding medium.}, archive = {J_ApJ}, author = {Haitian Shang and Wei Zhao and Xiaoyu Hong and Leonid I. Gurvits and Ailing Zeng and Tao An and Xiaopeng Cheng}, doi = {10.3847/1538-4357/adda31}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {169}, shortjournal = {The Astrophys. J.}, title = {Unveiling the complex jet dynamics in the blazar 2021+317 through multiepoch very long baseline interferometry observations}, volume = {987}, year = {2025}, }
• (2025). Time-resolved p-mode oscillations for subgiant HD 142091 with NEID at WIYN. ApJ, 987(2), 168. (www)

  @article{ , abstract = {Detections of Earth-analog planets in radial velocity (RV) observations are limited by stellar astrophysical variability occurring on a variety of timescales. Current state-of-the-art methods to disentangle potential planet signals from intrinsic stellar signals assume that stellar signals introduce asymmetries to the line profiles that can therefore be separated from the pure translational Doppler shifts of planets. Here, we examine this assumption using a time series of resolved stellar p -mode oscillations in HD 142091 ( κ CrB), as observed on a single night with the NEID spectrograph at 2 minutes cadence and with 25 cm s −1 precision. As an evolved subgiant star, this target has p -mode oscillations that are larger in amplitude (4–8 m s −1 ) and occur on longer timescales (80 minutes) than those of typical Sun-like stars of RV surveys, magnifying their corresponding effects on the stellar spectral profile. We show that for HD 142091, p -mode oscillations manifest primarily as pure Doppler shifts in the average line profile—measured by the cross-correlation function (CCF)—with “shape-driven” CCF variations as a higher-order effect. Specifically, we find that the amplitude of the shift varies across the CCF bisector, with 10% larger oscillation amplitudes closer to the core of the CCF and 25% smaller oscillation amplitudes for bisector velocities derived near the wings; we attribute this trend to larger oscillation velocities higher in the stellar atmosphere. Using a line-by-line analysis, we verify that a similar trend is seen as a function of average line depth, with deeper lines showing larger oscillation amplitudes. Finally, we find no evidence that p -mode oscillations have a chromatic dependence across the NEID bandpass beyond that due to intrinsic line depth differences across the spectrum.}, archive = {J_ApJ}, author = {Jacob K. Luhn and Paul Robertson and Samuel Halverson and Arvind F. Gupta and Jared C. Siegel and Jason T. Wright and Eric B. Ford and Suvrath Mahadevan and Timothy R. Bedding and Jaime A. Alvarado-Montes and Chad F. Bender and Jiayin Dong and Fred Hearty and Sarah E. Logsdon and Andrew Monson and Michael W. McElwain and Joe P. Ninan and Jayadev Rajagopal and Arpita Roy and Christian Schwab and Gudmundur Stefansson and Daniel J. Stevens and Ryan C. Terrien and Sharon Xuesong Wang and Jinglin Zhao}, doi = {10.3847/1538-4357/adda44}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {168}, shortjournal = {The Astrophys. J.}, title = {Time-resolved p-mode oscillations for subgiant HD 142091 with NEID at WIYN}, volume = {987}, year = {2025}, }
• (2025). The multiband emission of the two-component gamma-ray burst jet influenced by progenitor winds within the accretion disk of active galactic nuclei. ApJ, 987(2), 167. (www)

  @article{ , abstract = {Gamma-ray bursts (GRBs), both from the merger of binary compact objects (short GRBs) and the collapse of massive stars (long GRBs), are expected to occur in dense environments, e.g., the accretion disks of active galactic nuclei (AGNs). The propagating of GRB jets in such dense environments will result in multiband transients. Investigating the properties of these transients plays an important role in their identification, understanding the jet structure, and constraining the population of the star and compact objects in AGNs disks. In this work, we study the propagation and emission of a two-component GRB jet (a fast narrow component and a wide slow one) in an AGN disk. We consider the influence of wind from short and long GRB progenitors, which reconstruct the surrounding density distribution and form a cavity in the AGN disk. We find that long GRB jets are choked, and the dynamics and emission resemble the case without a cavity. The cocoon breakout emission can be detected by Einstein Probe (EP) and Hard X-ray Modulation Telescope (HXMT). For short GRBs, we expect a nonthermal afterglow emission from the narrow and wide jet (if it is more energetic than the narrow one) and a cocoon breakout emission from the choked wide jet, which can be monitored by EP and HXMT, respectively. Therefore, joint observations by EP and HXMT might be helpful to distinguish the types of GRBs in AGNs disks and the jet components.}, archive = {J_ApJ}, author = {Hao-Yu Yuan and Wei-Hua Lei}, doi = {10.3847/1538-4357/addbe4}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {167}, shortjournal = {The Astrophys. J.}, title = {The multiband emission of the two-component gamma-ray burst jet influenced by progenitor winds within the accretion disk of active galactic nuclei}, volume = {987}, year = {2025}, }
• (2025). Deep galaxy stellar mass functions as a function of star formation rate in the virgo cluster environment. ApJ, 987(2), 166. (www)

  @article{ , abstract = {We analyze deep ( M * ≳ 10 7 M ⊙ ) galaxy stellar mass functions (SMFs) of the Virgo cluster using stellar masses derived as part of the Next Generation Virgo Survey. The total SMF has a slope of \alpha =-1.3{5}_{-0.02}^{+0.02} , which is similar to or steeper than typical field values. Using deep H α data from the Virgo Environmental Survey Tracing Ionised Gas Emission we separate out star-forming galaxies, quiescent galaxies with no ongoing star formation, and low star formation rate (SFR) galaxies that are intermediate between these two populations. For each of these populations, the shape of the SMF is found to be universal throughout the cluster, from the core to the outskirts. The star-forming and quiescent SMFs show stark differences with values seen in field galaxies. The relative fraction of quiescent galaxies is highest in the core of the cluster, with low-SFR and star-forming galaxies more significant in the outer regions of the cluster. At low stellar masses ( M * ≲ 10 9 M ⊙ ), the quiescent fraction in the main cluster is significantly higher than that of the field and even satellites of massive groups. At high stellar masses, the quiescent fraction is similar to other studies of cluster galaxies. We model the quiescent population in the infall region of the cluster as a combination of backsplash and field quiescent galaxies, and find that the backsplash fractions needed to explain the observed population are unrealistically high. This suggests the existence of a third population of low-mass galaxies that are preprocessed outside the virial radius of the cluster, possibly in groups prior to infall.}, archive = {J_ApJ}, author = {Cameron R. Morgan and Elizaveta Sazonova and Ian D. Roberts and Michael L. Balogh and Joel Roediger and Laura Ferrarese and Patrick Côté and Alessandro Boselli and Matteo Fossati and Jean-Charles Cuillandre and Stephen Gwyn}, doi = {10.3847/1538-4357/addc6c}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {166}, shortjournal = {The Astrophys. J.}, title = {Deep galaxy stellar mass functions as a function of star formation rate in the virgo cluster environment}, volume = {987}, year = {2025}, }
• (2025). Can we discover physical models using machine learning? a case study of galaxy sizes. ApJ, 987(2), 165. (www)

  @article{ , abstract = {We explore the ability of machine learning methods to discover underlying equations of physics by searching for the equations governing galaxy size in a semianalytic model. This case study allows us to evaluate the process as we know the ground truth. We find that we fail to find an equation to predict galaxy size on the entire data set, but are successful when we separate out disk galaxies where we expect the physics driving galaxy size to be different than in bulge-dominated systems. We are also able to find an equation for bulge size, but not without adding an additional feature based on our knowledge of elliptical galaxy scaling relations.}, archive = {J_ApJ}, author = {Festa Buçinca-Çupallari and Ariyeh H. Maller and Viviana Acquaviva and Austen Gabrielpillai and Rachel S. Somerville}, doi = {10.3847/1538-4357/addc75}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {165}, shortjournal = {The Astrophys. J.}, title = {Can we discover physical models using machine learning? a case study of galaxy sizes}, volume = {987}, year = {2025}, }
• (2025). Channels of stellar-mass black hole formation. ApJ, 987(2), 164. (www)

  @article{ , abstract = {On the basis of a large collection of detailed 3D core-collapse supernova simulations carried to late times, we identify four channels of stellar-mass black hole formation. Our examples for Channel 1 can involve the formation of black holes in energetic asymmetric supernova explosions. Our Channel 2 example involves a modest supernova explosion that nevertheless leaves behind a black hole. The latter may not be easily distinguishable from “standard” supernovae that birth neutron stars. Our Channel 3 example experiences an aborted core-collapse explosion, more often in the context of a low-metallicity progenitor, whose residue is a black hole with a mass perhaps up to ∼40 M ⊙ . The latter may be accompanied by a pulsational pair-instability supernova. Channel 4 is the only quiescent or “silent” scenario for which perhaps ∼5–15 M ⊙ black holes are left. Where appropriate, we estimate 56 Ni yields, explosion energies, approximate recoil speeds, and residual black hole masses. The progenitor mass density and binding energy profiles at collapse influence the outcome in a systematic way. We speculate that the statistics and prevalence of these various channels depend not only on still evolving supernova theory, but on remaining issues with the theory of massive star evolution, binary interaction, wind mass loss, metallicity, and the nuclear equation of state. Importantly, we suggest, but have not proven, that the silent channel for black hole formation may not be the dominant formation modality.}, archive = {J_ApJ}, author = {Adam Burrows and Tianshu Wang and David Vartanyan}, doi = {10.3847/1538-4357/addd04}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {164}, shortjournal = {The Astrophys. J.}, title = {Channels of stellar-mass black hole formation}, volume = {987}, year = {2025}, }
• (2025). Continuum enhancement and line asymmetries of solar flares in different heating models: Alfvén waves, nonthermal electron beams, and their joint effect. ApJ, 987(2), 163. (www)

  @article{ , abstract = {How the plasma in the atmosphere is heated during a solar flare remains inconclusive. Nonthermal electron beams are usually considered as an essential heating source, yet Alfvén waves have also been proposed as a promising heating mechanism. Based on radiative hydrodynamic simulations, we explored the performance of different heating mechanisms, including nonthermal electron beams, Alfvén waves, and their joint effects. We studied the parameter space of Alfvén waves, focusing on the heating depth and the continuum emissions at 3600 and 6170 Å. We compared the atmospheric structures, continuum enhancements, and line profiles of hydrogen Ly α and H α in beam-heated, wave-heated, and jointly heated flare models. We find that the heating location of waves is strongly dependent on the wavenumber and frequency. The Alfvén wave can penetrate into the lower chromosphere and even the photosphere, causing a prominent continuum emission. There are different atmospheric responses in the Alfvén-wave and electron-beam heating cases due to their different energy-damping patterns. However, there seem to be no unique features in the Ly α and H α line profiles that can be used to distinguish the wave-heated models. In the jointly heated cases, the heating effect of waves and that of energetic electron beams can affect each other during the evolution of flares. Our simulations provide some references for interpreting the observed line profiles as well as the continuum emissions in solar white-light flares.}, archive = {J_ApJ}, author = {Jun Tian and Ying Li and Jie Hong and M. D. Ding}, doi = {10.3847/1538-4357/addd0e}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {163}, shortjournal = {The Astrophys. J.}, title = {Continuum enhancement and line asymmetries of solar flares in different heating models: Alfvén waves, nonthermal electron beams, and their joint effect}, volume = {987}, year = {2025}, }
• (2025). Low-velocity precessing jets can explain observed morphologies in the twin radio galaxy TRG j104454+354055. ApJ, 987(2), 162. (www)

  @article{ , abstract = {Our understanding of large-scale radio jets in merger systems has been drastically improved in the era of the Very Large Array, Very Long Baseline Array/European VLBI Network, upgraded Giant Metrewave Radio Telescope, and MeerKAT. Twin radio galaxies (TRGs) are rare interacting galaxy pairs where both supermassive black holes host kiloparsec-scale bipolar radio jets. Only recently was a third TRG discovered, and it shows significantly different jet morphologies than the previous two. Due to both the extreme paucity and complexity of such systems, the launching of their jets as well as their mutual interaction during the propagation through the ambient medium are not well understood. We have performed three-dimensional hydrodynamic simulations to study the bipolar jets in the third TRG, J104454+354055. Our study indicates that the precession of mutually tilted bipolar jets originating from the two galactic nuclei separated by tens of kiloparsecs and propagating at low velocities can explain the observed morphologies. The simulated jet precession timescales are short compared to the overall dynamical timescale of the jets, and could originate from Lense–Thirring effect in the accretion disks. This approach to understanding TRG jet dynamics could also be applied to other TRG systems with similar helical morphologies that may be discovered in the upcoming era of the Square Kilometre Array and its pathfinder surveys.}, archive = {J_ApJ}, author = {Santanu Mondal and Gourab Giri and Ravi Joshi and Paul J. Wiita and Gopal-Krishna and Luis C. Ho}, doi = {10.3847/1538-4357/ade058}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {162}, shortjournal = {The Astrophys. J.}, title = {Low-velocity precessing jets can explain observed morphologies in the twin radio galaxy TRG j104454+354055}, volume = {987}, year = {2025}, }
• (2025). Variations in dominant wave period in the solar atmosphere. ApJ, 987(2), 161. (www)

  @article{ , abstract = {Waves are an integral part of the solar atmosphere, and their characteristics (e.g., dominant period, range of periods, power, and phase angle) change on a diverse spatiotemporal scale. It is well established observationally that the dominant periods of solar oscillations are 5 and 3 minutes in the photosphere and chromosphere, respectively. This shows that the wave spectra and their dominant periods evolve between these two layers. We present observational results that demonstrate variations of the dominant period with heights in the photosphere and chromosphere. Six photospheric absorption lines and one chromospheric line are analyzed by using the Interface Region Imaging Spectrograph data, and the Doppler velocity time series at seven different atmospheric heights are determined. The wavelet analysis is applied to these time series, and the resulting spectrum of wave periods and its dominant period are deduced at these heights, which gives height variations of the dominant period. The obtained data show that the dominant period decreases with height and that there are also changes in the range of wave periods within the spectrum. Numerical simulations of filtered wave spectra through the solar atmosphere are also performed, and the obtained results match the observational data.}, archive = {J_ApJ}, author = {Pradeep Kayshap and K. Murawski and Z. E. Musielak and B. Suresh Babu}, doi = {10.3847/1538-4357/ade14e}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {161}, shortjournal = {The Astrophys. J.}, title = {Variations in dominant wave period in the solar atmosphere}, volume = {987}, year = {2025}, }
• (2025). Carbon-rich dust injected into the interstellar medium by galactic WC binaries survives for hundreds of years. ApJ, 987(2), 160. (www)

  @article{ , abstract = {Some carbon-rich Wolf–Rayet (WC) stars show an infrared excess from dust emission (WCd stars). Dust forms in the collision of the WC wind with a companion star’s wind. As this dust is carried toward the interstellar medium (ISM) at close to the WCd wind speed and the binary continues through its orbit, a spiral structure forms around the system. The shape depends on the orbital eccentricity and period, as well as stellar parameters like mass-loss rates and terminal wind speeds. Imaging of the WCd binary WR 140 with JWST/MIRI revealed 17 concentric dust shells surrounding the binary. We present new JWST imaging of four additional WCd systems (WR 48a, WR 112, WR 125, and WR 137) that were imaged in 2024. In this analysis, we show that the dust is long-lived, detected with an age of at least 130 yr, but more than 300 yr in some systems. Longer-duration measurements are limited by sensitivity. Regular spacing of dust features confirms the periodic nature of dust formation, consistent with a connection to binary motion. We use these images to estimate the proper motion of the dust, finding the dust to propagate out to the ISM with motion comparable to the wind speed of the WC stars. In addition to these results, we observe unusual structures around WR 48a, which could represent dusty clumps shaped by photoevaporation and wind ablation like young proplyd objects. These results demonstrate that WC dust is indeed long-lived and should be accounted for in galactic dust budgets.}, archive = {J_ApJ}, author = {Noel D. Richardson and Micaela Henson and Emma P. Lieb and Corey Kehl and Ryan M. Lau and Peredur M. Williams and Michael F. Corcoran and J. R. Callingham and André-Nicolas Chené and Theodore R. Gull and Kenji Hamaguchi and Yinuo Han and Matthew J. Hankins and Grant M. Hill and Jennifer L. Hoffman and Jonathan Mackey and Anthony F. J. Moffat and Benjamin J. S. Pope and Pragati Pradhan and Christopher M. P. Russell and Andreas A. C. Sander and Nicole St-Louis and Ian R. Stevens and Peter Tuthill and Gerd Weigelt and Ryan M. T. White}, doi = {10.3847/1538-4357/addf30}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {160}, shortjournal = {The Astrophys. J.}, title = {Carbon-rich dust injected into the interstellar medium by galactic WC binaries survives for hundreds of years}, volume = {987}, year = {2025}, }
• (2025). Radiative relativistic turbulence as an in situ pair-plasma source in blazar jets. ApJ, 987(2), 159. (www)

  @article{ , abstract = {As powerful gamma-ray engines, blazars—relativistic plasma jets launched toward Earth from active galactic nuclei—are manifestly high-energy particle accelerators. Yet, exactly how these jets accelerate particles as well as what they are made of both remain largely mysterious. In this work, we argue that these issues may be linked through the gamma-ray emission for which blazars are renowned. Namely, high-energy photons produced at sites of intense particle acceleration could be absorbed by soft radiation within the jet, enriching it with electron–positron pairs. We explore this possibility in the specific context of particle acceleration by magnetized radiative relativistic turbulence. Using a combination of theory, particle-in-cell simulations, and Fokker–Planck modeling, we identify and characterize a novel pair-production-mediated equilibration mechanism in such turbulence. Initially, turbulent energy injection outpaces radiative cooling, leading to runaway particle acceleration and gamma-ray radiation. Then, gamma-ray absorption begets copious newborn pairs, slowing subsequent particle acceleration. This eventually brings particle acceleration into balance with radiative cooling and shuts down pair production: a pair-enriched final equilibrium. We estimate that this process could significantly load jets of flat-spectrum radio quasars with fresh pairs. These results represent an important connection between particle acceleration and plasma composition in blazar jets.}, archive = {J_ApJ}, author = {John M. Mehlhaff and Muni Zhou and Vladimir Zhdankin}, doi = {10.3847/1538-4357/addb47}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {159}, shortjournal = {The Astrophys. J.}, title = {Radiative relativistic turbulence as an in situ pair-plasma source in blazar jets}, volume = {987}, year = {2025}, }
• (2025). A comparative study of the ground state transitions of CO and c i as molecular gas tracers at high redshift. ApJ, 987(2), 158. (www)

  @article{ , abstract = {The CO(1–0) and [C i ](1–0) emission lines are well-established tracers of cold molecular gas mass in local galaxies. At high redshift, where the interstellar medium is likely to be denser, there have been limited direct comparisons of both ground-state transitions. We present a comparison of [C i ](1–0) and CO(1–0) emission in 20 unlensed dusty, star-forming galaxies at z ≥ 2–5. The CO(1–0)/[C i ](1–0) ratio remains constant up to z = 5, supporting the reliability of [C i ](1–0) as a gas–mass tracer. We use the CO(1–0), [C i ](1–0), and 3 mm dust continuum measurements to cross–calibrate their respective gas mass conversion factors, finding no dependence of these factors on either redshift or infrared luminosity. Radiative transfer modeling shows that the warmer cosmic microwave background (CMB) at high redshift can significantly affect the [C i ] as well as CO emission, which can change the derived molecular gas masses by up to 70% for the coldest kinetic gas temperatures expected. Nevertheless, the magnitude of the CMB effect on the CO/[C i ] ratio is within the known scatter of the {L}_{\mathrm{CO}}^{{\prime} }-{L}_{[\mathrm{CI}]}^{{\prime} } relation. Precisely determining the CMB effect on individual line intensities would require well-sampled spectral line energy distributions to robustly model the gas excitation conditions. Finally, we note that adopting a variable CO gas–mass conversion factor for different galaxy populations implies [C i ](1–0) and dust conversion factors that differ from canonically assumed values. However, the revised conversion factors are consistent with expectations for (super)solar metallicities likely to be found in high-redshift dusty galaxies.}, archive = {J_ApJ}, author = {Marta Frias Castillo and Matus Rybak and Jacqueline A. Hodge and Paul van der Werf and Ian Smail and Joshua Butterworth and Jasper Jansen and Theodoros Topkaras and Chian-Chou Chen and Scott C. Chapman and Axel Weiss and Hiddo Algera and Jack E. Birkin and Elisabete da Cunha and Jianhang Chen and Helmut Dannerbauer and Soh Ikarashi and E. F. Jiménez-Andrade and Cheng-Lin Liao and Eric J. Murphy and A. M. Swinbank and Fabian Walter and Gabriela Calistro Rivera and R. J. Ivison and Claudia del P. Lagos}, doi = {10.3847/1538-4357/adc4e0}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {158}, shortjournal = {The Astrophys. J.}, title = {A comparative study of the ground state transitions of CO and c i as molecular gas tracers at high redshift}, volume = {987}, year = {2025}, }
• (2025). On the accuracy and uncertainty of coronal mass ejection 3D reconstructions depending on the number of viewpoints in the heliosphere. ApJ, 987(2), 157. (www)

  @article{ , abstract = {This paper presents a systematic study that focuses on how the number of viewpoints distributed in the heliosphere affects the accuracy and uncertainty of the 3D geometric coronal mass ejection (CME) measurements. An efficient nonmanual minimization-based fitting technique that is different from the manual methods widely used in the community is developed. It uses the MPFIT minimization IDL routine and searches for the optimized model point clouds that best fit the observed CME leading edges from one, two, or three viewpoints using a set of combinations of observations provided by the Solar Terrestrial Relations Observatory and Solar and Heliospheric Observatory. The technique also provides a robust calculation of uncertainties of the CME geometric parameters that is lacking in manual methods. Three well-known geometric models, the cone, graduated cylindrical shell, and spheroid shock, are used. All three models depend on geometric parameters that govern the CME propagation direction and size. Sample cases of a halo, partial halo, and limb CMEs as seen from the Earth are used in the fitting and uncertainty calculation. It is found that, after adding a second viewpoint off the Sun–Earth line, the uncertainties drop significantly, while the addition of the third viewpoint adds limited benefits. This study shows that the minimization fitting method provides a robust, fast, and straightforward way to define the CME geometric parameters along with their uncertainties for individual events, which shall provide the necessary data constraints for ensemble predictions of CME evolution. It also underlines the importance of having a permanent observatory off the Sun–Earth line for operational space weather prediction.}, archive = {J_ApJ}, author = {Eleni Nikou and Jie Zhang and Suman K. Dhakal and Matthew Dupertuis}, doi = {10.3847/1538-4357/adcef0}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {157}, shortjournal = {The Astrophys. J.}, title = {On the accuracy and uncertainty of coronal mass ejection 3D reconstructions depending on the number of viewpoints in the heliosphere}, volume = {987}, year = {2025}, }
• (2025). Modeling polarized radio sounding observations of a coronal mass ejection. ApJ, 987(2), 156. (www)

  @article{ , abstract = {Coronal mass ejections (CMEs) evolve significantly as they propagate from the Sun to the Earth, so remote observations of their changes in speed, strength of the magnetic field, density, and overall structure are critical for predicting their arrival time and geoeffectiveness. Radio line-of-sight observations of Faraday rotation and total electron content (TEC) combined with white-light observations enable the measurement of these properties with careful analyses. This paper describes the analysis techniques and evaluates their accuracy with regard to measuring a CME’s complex evolving structure and speed. The approach utilizes the layout of the Faraday effect tracker of coronal and heliospheric structures, a purely space-based instrument concept, with Alfvén Wave Solar atmosphere Model (AWSoM) simulations as input for evaluating these radio-based measures. Focusing on density and velocity/speed, we find that in situ measurements of CME properties observe similar but different aspects of the distinct CME structure. The AWSoM model suggests that Faraday rotation may be a more sensitive measure of structure than TEC. Finally, we discuss the difficulty the simulation reveals in determining the trailing edge location of a magnetic flux rope.}, archive = {J_ApJ}, author = {Elizabeth A. Jensen and W. B. Manchester and J. E. Kooi and T. Nieves-Chinchilla and L. K. Jian and D. B. Wexler and S. F. Fung and N. Gopalswamy}, doi = {10.3847/1538-4357/add1c3}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {156}, shortjournal = {The Astrophys. J.}, title = {Modeling polarized radio sounding observations of a coronal mass ejection}, volume = {987}, year = {2025}, }
• (2025). The sloan digital sky survey reverberation mapping project: Insights on maximizing efficiency in lag measurements and black hole masses. ApJ, 987(2), 155. (www)

  @article{ , abstract = {Multiyear observations from the Sloan Digital Sky Survey (SDSS) Reverberation Mapping ​(RM) project have significantly increased the number of quasars with reliable RM lag measurements. We statistically analyze target properties, light-curve characteristics, and survey design choices to identify factors crucial for successful and efficient RM surveys. Analyzing 172 high-confidence (“gold”) lag measurements from SDSS-RM for the H β , Mg ii , and C iv emission lines, we find that the Durbin–Watson statistic (a statistical test for residual correlation) is the most significant predictor of light curves suitable for lag detection. The variability signal-to-noise ratio and emission-line placement on the detector also correlate with successful lag measurements. We further investigate the impact of the observing cadence on the survey design by analyzing the effect of reducing observations in the first year of SDSS-RM. Our results demonstrate that a modest reduction in the observing cadence to ∼1.5 weeks between observations can retain approximately 90% of the lag measurements compared to twice-weekly observations in the initial year. Provided similar and uniform sampling in subsequent years, this adjustment has a minimal effect on the overall recovery of lags across all emission lines. These results provide valuable inputs for optimizing future RM surveys.}, archive = {J_ApJ}, author = {Y. Homayouni and Yuanzhe Jiang and W. N. Brandt and C. J. Grier and Jonathan R. Trump and Yue Shen and Keith Horne and Patrick B. Hall and Scott F. Anderson and Luis C. Ho and D. P. Schneider}, doi = {10.3847/1538-4357/add34e}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {155}, shortjournal = {The Astrophys. J.}, title = {The sloan digital sky survey reverberation mapping project: Insights on maximizing efficiency in lag measurements and black hole masses}, volume = {987}, year = {2025}, }
• (2025). Growth of massive molecular cloud filament by accretion flows. II. new mechanism to support a supercritical filament against radial collapse. ApJ, 987(2), 154. (www)

  @article{ , abstract = {Observations indicate that dense molecular filamentary clouds are sites of star formation. The filament width determines the most unstable scale for self-gravitational fragmentation and influences the stellar mass. Therefore, constraining the evolution of filaments and the origin of their properties is important for understanding star formation. Although some observations show a universal width of 0.1 pc, many theoretical studies predict the contraction of thermally supercritical filaments (>17 M ⊙ pc −1 ) due to radial collapse. Through nonideal magnetohydrodynamics simulations with ambipolar diffusion, we explore the formation and evolution of filaments via slow-shock instability at the front of accretion flows. We reveal that ambipolar diffusion allows the gas in the filament to flow across the magnetic fields around the shock front, forming dense blobs behind the concave points of the shock front. The blobs transfer momentum that drives internal turbulence. We name this mechanism “the STORM”(Slow-shock-mediated Turbulent flOw Reinforced by Magnetic diffusion). The persistence and efficiency of the turbulence inside the filament are driven by the magnetic field and the ambipolar diffusion effect, respectively. The STORM mechanism sustains the width even when the filament reaches very large line masses (∼100 M ⊙ pc −1 ).}, archive = {J_ApJ}, author = {Daisei Abe and Tsuyoshi Inoue and Shu-ichiro Inutsuka and Doris Arzoumanian}, doi = {10.3847/1538-4357/add529}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {154}, shortjournal = {The Astrophys. J.}, title = {Growth of massive molecular cloud filament by accretion flows. II. new mechanism to support a supercritical filament against radial collapse}, volume = {987}, year = {2025}, }
• (2025). Resistive tearing mode instability in generalized harris current sheets. ApJ, 987(2), 153. (www)

  @article{ , abstract = {The widely adopted initial force-balanced equilibrium prior to the occurrence of magnetic reconnection (MR) is the so-called Harris sheet model with antiparallel magnetic field. This study examines the tearing mode instability of the recently developed generalized Harris sheet equilibrium based on two-dimensional, resistive, isotropic, linear, and nonlinear MHD models. The generalized Harris equilibrium incorporating the nonthermal Kappa-like velocity distributions in the Vlasov–Maxwell equations may give rise to a family of plasma and magnetic field profiles with various current layer thicknesses which may be used to study various plasma instabilities and MR. It is shown that the linear growth rate is proportional to {\delta }^{-2/5}{R}_{m}^{-2/5} , where \delta and {R}_{m} are the current layer thickness and magnetic Reynolds number, respectively. The linear eigenmode solutions are used as the initial perturbations of the nonlinear MHD simulations to allow the full evolution of the tearing instability. It is shown that the cases with small {R}_{m} may not be nonlinearly unstable, and the cases with relatively thinner current sheets and larger {R}_{m} may grow faster with larger aspect ratios of magnetic islands. In the generalized kinetic Harris models, the thinning of current sheets may be achieved by the decrease of central temperature or the increase of the drift velocity of charged particles. The asymptotic magnetic field of the equilibrium profiles seems to play a minor role in the linear and nonlinear growth of resistive tearing mode instability.}, archive = {J_ApJ}, author = {C.-K. Chang and L.-N. Hau}, doi = {10.3847/1538-4357/add682}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {153}, shortjournal = {The Astrophys. J.}, title = {Resistive tearing mode instability in generalized harris current sheets}, volume = {987}, year = {2025}, }
• (2025). Dynamical inference from polarized light curves of sagittarius a*. ApJ, 987(2), 152. (www)

  @article{ , abstract = {Polarimetric light curves of Sagittarius A* (Sgr A*) sometimes exhibit loops in the Stokes Q and U plane over time, often interpreted as orbiting hotspot motion. In this work, we apply the differential geometry of planar curves to develop a new technique for estimating polarimetric rotation rates. Applying this technique to 230 GHz light curves of Sgr A*, we find evidence of clockwise motion not only during a postflare period on 2017 April 11, as previously discovered, but also during the quiescent days imaged by the Event Horizon Telescope (EHT). The data exhibit a clockwise fraction of 0.65 ± 0.09 and an overall Q − U rotation rate of -2.6\pm 0.6\,\deg \,{t}_{g}^{-1} . We analyze a library of general relativistic magnetohydrodynamic simulations and find that face-on, clockwise-rotating models with strong magnetic fields are most likely to be consistent with the observations. These results are consistent with EHT and GRAVITY Collaboration studies and indirectly support an interpretation in which the polarized image of Sgr A* has been rotated by an external Faraday screen. This technique offers a novel probe of event-horizon-scale dynamics that complements dynamical reconstructions.}, archive = {J_ApJ}, author = {Angelo Ricarte and Nicholas S. Conroy and Maciek Wielgus and Daniel C. M. Palumbo and Razieh Emami and Chi-Kwan Chan}, doi = {10.3847/1538-4357/add729}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {152}, shortjournal = {The Astrophys. J.}, title = {Dynamical inference from polarized light curves of sagittarius a*}, volume = {987}, year = {2025}, }
• (2025). Simulation of solar energetic particle events originated from coronal mass ejection shocks with a data-driven physics-based transport model. ApJ, 987(2), 151. (www)

  @article{ , abstract = {Solar energetic particle (SEP) events are associated with coronal mass ejections (CMEs) and/or solar flares. SEPs travel through the corona and interplanetary space to reach Earth, posing a radiation hazard to spacecraft and astronauts working in space and the electronics on spacecraft. Due to the distinct magnetic field configuration and solar eruption kinematic properties associated with each event, the use of a data-driven model becomes essential for predicting SEP hazards. In this study, we use a developed model that utilizes photospheric magnetic field measurements and CME-driven shock observations as inputs to simulate several historical SEP events associated with fast CME speeds (>700 km s −1 ). The model includes an SEP source term aligned with the theory of diffusive shock acceleration by the CME-driven shock. The performance of the model is assessed by comparing simulations and observations of SEP intensity-time profiles at Solar and Heliospheric Observatory, ACE, STEREO-A, and STEREO-B. The results generally match the observations well, particularly for protons below 40.0 MeV. However, discrepancies arose for higher-energy protons, notably for the events on 2011 March 7 and 2014 February 25, where the simulation tends to overestimate the proton flux. At STEREO-A, the modeled proton intensities for the SEP events on 2013 April 11 and 2011 March 7 display a very different behavior compared to observations because of the efficient transport in longitude caused by the weak magnetic field.}, archive = {J_ApJ}, author = {Lei Cheng and Ming Zhang and Ryun Young Kwon and David Lario}, doi = {10.3847/1538-4357/add892}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {151}, shortjournal = {The Astrophys. J.}, title = {Simulation of solar energetic particle events originated from coronal mass ejection shocks with a data-driven physics-based transport model}, volume = {987}, year = {2025}, }
• (2025). A general, differentiable transit model for ellipsoidal occulters: Derivation, application, and forecast of planetary oblateness and obliquity constraints with JWST. ApJ, 987(2), 150. (www)

  @article{ , abstract = {Increasingly precise space-based photometry uncovers higher-order effects in transits, eclipses, and phase curves that can be used to characterize exoplanets in novel ways. The subtle signature induced by a rotationally deformed exoplanet is determined by the planet’s oblateness and rotational obliquity, which provide a wealth of information about a planet’s formation, internal structure, and dynamical history. However, oblateness and obliquity are often strongly degenerate and require sophisticated methods to convincingly constrain. We develop a new semianalytic model for an ellipsoidal object occulting a spherical body with arbitrary surface maps expressed in terms of spherical harmonics. We implement this model in an open-source J ax -based Python package eclipsoid ( https://github.com/shishirdholakia/eclipsoid ), allowing just-in-time compilation and automatic differentiation. We then estimate the precision obtainable with JWST observations of the long-period planet population and demonstrate the best current candidates for studies of oblateness and obliquity. We test our method on the JWST NIRSpec transit of the inflated warm Neptune WASP-107 b and place an upper bound on its projected oblateness of f < 0.23, which corresponds to a rotation period of P rot > 13 hr if the planet is not inclined to our line of sight. Further studies of long-period exoplanets will necessitate discarding the assumption of planets as spherical bodies. Eclipsoid provides a general framework allowing rotational deformation to be modeled in transits, occultations, phase curves, transmission spectra, and more. ✎ ✎}, archive = {J_ApJ}, author = {Shashank Dholakia and Shishir Dholakia and Benjamin J. S. Pope}, doi = {10.3847/1538-4357/addb4e}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {150}, shortjournal = {The Astrophys. J.}, title = {A general, differentiable transit model for ellipsoidal occulters: Derivation, application, and forecast of planetary oblateness and obliquity constraints with JWST}, volume = {987}, year = {2025}, }
• (2025). Multiphase shock cooling emission in ultrastripped supernovae. ApJ, 987(2), 149. (www)

  @article{ , abstract = {Ultrastripped and Type Ibn supernovae (USSNe and SNe Ibn, respectively) are fast-evolving, hydrogen-poor transients that often show signs of interaction with dense circumstellar material (CSM). S. C. Wu & J. Fuller identify a mass range for helium-core stars in which they expand significantly during core oxygen/neon burning, resulting in extreme late-stage mass loss in tight binaries ( P ∼ 1–100 days). Here we explore the resulting light curves from a subset of models from S. C. Wu & J. Fuller and find that in some cases they can exhibit two phases of shock cooling emission (SCE). The first SCE is attributed to the circumbinary material, and the second is from the extended helium-burning envelope of the exploding star. Since SCE luminosity is roughly proportional to the initial radius of the emitting material, events that exhibit both phases of SCE provide the exciting opportunity of measuring both the extent of the CSM and the radius of the exploding star. These light curves are explored with both analytic arguments and numerical modeling, and from this we identify the parameter space of CSM mass, helium envelope (HE) mass, and nickel mass, for which the HE SCE will be visible. We provide a qualitative comparison of these models to two fast-evolving, helium-rich transients, SN 2019kbj and SN 2019dge. The similarity between these events and our models demonstrates that this extreme binary mass loss mechanism may explain some SNe Ibn and USSNe.}, archive = {J_ApJ}, author = {Annastasia Haynie and Samantha C. Wu and Anthony L. Piro and Jim Fuller}, doi = {10.3847/1538-4357/addc72}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {149}, shortjournal = {The Astrophys. J.}, title = {Multiphase shock cooling emission in ultrastripped supernovae}, volume = {987}, year = {2025}, }
• (2025). Numerical simulation of oscillatory magnetic reconnection modulated by solar convective motions. ApJ, 987(2), 148. (www)

  @article{ , abstract = {Oscillatory magnetic reconnection is a periodic magnetic reconnection process, during which the current sheet’s orientation and the magnetic connections change periodically. This periodic variation is generally considered to originate from the magnetic reconnection itself rather than from external driving processes. We conduct 2.5D radiative magnetohydrodynamic simulations to investigate the emergence of a magnetic flux tube from the convection zone into the lower corona, where the emerging magnetic fields reconnect with background ones. During the reconnection process, within 5771 s the current sheet’s orientation has been reversed 41 times, corresponding to 40 oscillation periods. Notably, the longest period is 30 minutes, which is consistent with the previous observational results. We find that the main factor leading to the reversal of the current sheet’s orientation is the quasi-periodic external force provided by the emergence of plasma and magnetic fields from the convection zone. We also find the shifting of the upward outflows from the reconnection region along the horizontal direction due to the alternating changes of the reconnection inflow and outflow regions. In addition to the quasi-periodic change of the current sheet orientation, the reconnection rate at the main X-point also oscillates with a period between 100 and 400 s, which corresponds to the period of p -mode oscillations.}, archive = {J_ApJ}, author = {Yifu Wang and Lei Ni and Guanchong Cheng and Jialiang Hu and Yuhao Chen and Abdullah Zafar}, doi = {10.3847/1538-4357/addd15}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {148}, shortjournal = {The Astrophys. J.}, title = {Numerical simulation of oscillatory magnetic reconnection modulated by solar convective motions}, volume = {987}, year = {2025}, }
• (2025). New symbiotic stars from LAMOST DR10 spectra and multiband photometry. ApJ, 987(2), 147. (www)

  @article{ , abstract = {The Symbiotic star (SySt) is a long-period interacting binary system, typically consisting of a white dwarf (WD) and a red giant surrounded by a nebula. These systems are natural astrophysical laboratories for investigating binary star evolution. In this paper, we identified nine SySts from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) DR10 low-resolution spectra survey, seven of which were previously known, while two are newly identified. Initially, we selected LAMOST spectra exhibiting typical SySt emission lines (e.g., H α , H β , H γ , and He II ). Subsequently, we utilized the distribution of known SySts on the Hertzsprung–Russell diagram to select SySt candidates, and visually inspected their spectra. Ultimately, we classified all nine as S-type SySts using the J − H versus H − K s diagram. Additionally, based on multiband photometric data from GALEX, Gaia, Two Micron All Sky Survey, ALLWISE, and several X-ray catalogs, we found 12 accreting-only SySt (acc-SySt) candidates, characterized by concurrent ultraviolet and infrared excess and accretion process. Furthermore, we estimated the WD temperatures by fitting their observed spectral energy distributions using a combination of the Kurucz stellar atmosphere model and the Koester WD model. We compared the accretion rates of acc-SySt candidates and confirmed SySts, and found they have similar accretion rate distributions, providing evidence that these acc-SySt candidates constitute bona fide SySts.}, archive = {J_ApJ}, author = {Jing Chen and Liang Wang and Yin-Bi Li and Xiao-Xiao Ma and A-Li Luo and Zi-Chong Zhang and Ming-Yi Ding and Kai Zhang}, doi = {10.3847/1538-4357/addec3}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {147}, shortjournal = {The Astrophys. J.}, title = {New symbiotic stars from LAMOST DR10 spectra and multiband photometry}, volume = {987}, year = {2025}, }
• (2025). Gravitational-wave kicks impact the spins of black holes from hierarchical mergers. ApJ, 987(2), 146. (www)

  @article{ , abstract = {One proposed black hole formation channel involves hierarchical mergers, where black holes form through repeated binary mergers. Previous studies have shown that such black holes follow a near-universal spin distribution centered around 0.7. However, gravitational-wave kicks can eject remnants from their host environments, meaning only retained black holes can participate in subsequent mergers. We calculate the spin distribution of retained black holes in typical globular clusters, accounting for remnant kick velocities. Since the kick magnitude depends on the binary’s mass ratio and spin orientations, certain configurations are more likely to be retained than others. This preferentially selects certain remnant spin magnitudes, skewing the spin distribution of second-generation black holes away from the universal distribution. In low escape velocity environments, the distribution can become bimodal, as remnants with spins of 0.7 typically receive larger kicks than in other configurations. Regarding higher-generation black holes, their spin distribution does not converge to a unique form, and can span a broad range of spins, a f ∈ (0.4, 1), depending on their merger history, birth spins, and the escape velocity. Additionally, we find that the presence of a small fraction of binaries with near-aligned spins can produce a second, more dominant peak, whose position depends on the birth spin magnitude. Our findings identify observable features of hierarchical merger black holes, which is essential for understanding their contribution to the gravitational-wave population. Moreover, the dependence of the spin distribution on astrophysical parameters means that precise spin measurements could provide insights into their formation environments.}, archive = {J_ApJ}, author = {Angela Borchers and Claire S. Ye and Maya Fishbach}, doi = {10.3847/1538-4357/addec6}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {146}, shortjournal = {The Astrophys. J.}, title = {Gravitational-wave kicks impact the spins of black holes from hierarchical mergers}, volume = {987}, year = {2025}, }
• (2025). Global resistive magnetohydrodynamic accretion flows around spinning active galactic nuclei: Impact of resistivity on the magnetically arrested disk state. ApJ, 987(2), 145. (www)

  @article{ , abstract = {In this study, we investigate the effect of resistivity on the dynamics of global magnetohydrodynamic accretion flows (Res-MHD) around a spinning supermassive black hole. We perform a comparative study of two-dimensional (2D) and three-dimensional (3D) resistive models around black holes. We examine accretion flow dynamics considering globally uniform resistivity values ranging from ∼0 to 0.1. During the simulation time of t ≲ 1000 t g , we find that the mass accretion rate is comparable for both the 2D and 3D models. However, as the flow becomes increasingly turbulent, nonaxisymmetric effects begin to dominate, resulting in significant differences in the mass accretion rates between the 3D and 2D. All the resistive models in a highly magnetized flow belong to the magnetically arrested disk (MAD) state. We propose an efficient and physically motivated approach to examine the magnetic state by estimating the spatial average plasma beta parameter across the computational domain. We find that when the average plasma beta is close to or below unity ( β ave ≲ 1), the accretion flow enters the MAD state. Additionally, we find that high-resistivity flow reduces magnetorotational instability turbulence in the accretion flow, while the turbulence structures remain qualitatively similar in low-resistivity flows. Moreover, we observe indications of plasmoid formations in low-resistivity flow compared to high-resistivity flow. Furthermore, we do not find a clear relationship between the variability of the accretion rate, magnetic flux, and resistivity. Lastly, our findings suggest that low-resistivity models produce higher-power jets than those with higher resistivity.}, archive = {J_ApJ}, author = {Ramiz Aktar and Kuo-Chuan Pan and Toru Okuda}, doi = {10.3847/1538-4357/ade05a}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {145}, shortjournal = {The Astrophys. J.}, title = {Global resistive magnetohydrodynamic accretion flows around spinning active galactic nuclei: Impact of resistivity on the magnetically arrested disk state}, volume = {987}, year = {2025}, }
• (2025). Oscillatory line-driven winds: The role of atmospheric stratification. ApJ, 987(2), 144. (www)

  @article{ , abstract = {Time-dependent numerical studies of line-driven winds using the Sobolev approximation have a history spanning over three decades. In many of these studies, the wind solutions display notorious oscillations. Two clues suggest the oscillations originate at the wind base: (i) simulations reach a steady state without oscillations when the base density is sufficiently low, and (ii) the oscillation dominant frequency is comparable to the Lamb cutoff frequency, ω c , of acoustic waves propagating in a stratified hydrostatic atmosphere. Recently, Dannen et al. observed another clue: When the line force significantly weakens due to ionization, the winds become increasingly sensitive to the self-excited oscillations. Here, we present a set of simulations and perturbation analyses that further elucidate the source and characteristics of oscillations. We found that the line force adds wave energy and amplifies perturbations with frequencies near ω c . This selective amplification results from the coupling between the natural tendency of velocity perturbations to grow in a stratified atmosphere and from the line force dependence on the velocity gradient, per the Castor–Abbott–Klein line-driven wind theory. We also found that the variability stems from self-excitation that occurs in the exponential atmosphere due to the nonlinearity introduced by the absolute value of the velocity gradient in the line force prescription. We conclude that self-consistently calculating ionization is insufficient for modeling the dynamics in the subsonic atmosphere. Instead, future wind or unified models should relax the Sobolev approximation, or model the radiative transfer to properly capture the resulting radiation-induced instabilities and dynamics at the wind base.}, archive = {J_ApJ}, author = {Joshua A. Key and Daniel Proga and Randall Dannen and Sterling Vivier and Tim Waters}, doi = {10.3847/1538-4357/adcf19}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {144}, shortjournal = {The Astrophys. J.}, title = {Oscillatory line-driven winds: The role of atmospheric stratification}, volume = {987}, year = {2025}, }
• (2025). The shape and mass of the galactic dark matter halo from the axisymmetric jeans model. ApJ, 987(2), 143. (www)

  @article{ , abstract = {We explore the density profile, shape, and virial mass of the Milky Way’s dark matter halo, using K giants (KGs) from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope and Sloan Digital Sky Survey (SDSS)/SEGUE as well as blue horizontal branch stars (BHBs) from SDSS. Incorporating Gaia DR3 proper motions, we first investigate the velocity ellipsoid distribution within the ( R , ∣ z ∣) space. The ellipsoids projected onto the ( v R , v z ) plane exhibit near-spherical alignment. We then probe the underlying dark matter distribution, using the axisymmetric Jeans equations with multi-Gaussian expansion and spherically aligned Jeans anisotropic modeling (JAMsph), allowing for different flattened dark matter density models. For each model, we apply two fitting approaches: fitting the KGs and BHBs separately or fitting them simultaneously as two dynamical tracers in one gravitational potential. We find consistent results for the dark matter density profiles, r 200 , and M 200 within a 1 σ confidence region for models constrained by KGs, BHBs, and both. We find the strongest consistency between KGs and BHBs in constraining dark matter profiles for models incorporating radially varying halo flattening ( q ( r gc )), which suggests the Milky Way’s dark matter halo shape evolves with Galactocentric distance ( r gc ). Specifically, the halo flattening parameter q h decreases within r gc < 20 kpc and increases for r gc > 20 kpc. In this model, {M}_{\mathrm{tot}}(\lt 60\,\mathrm{kpc})=0.53{3}_{-0.054}^{+0.061}\times 1{0}^{12} M ⊙ , r 200 is 188 ± 15 kpc, and M 200 is estimated at 0.82{0}_{-0.186}^{+0.210}\times 1{0}^{12}{M}_{\odot } .}, archive = {J_ApJ}, author = {Lan Zhang and Xiang-Xiang Xue and Ling Zhu and Ruizhi Zhang and Chengqun Yang and Shi Shao and Jiang Chang and Feilu Wang and Hao Tian and Gang Zhao and Chao Liu}, doi = {10.3847/1538-4357/add886}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {143}, shortjournal = {The Astrophys. J.}, title = {The shape and mass of the galactic dark matter halo from the axisymmetric jeans model}, volume = {987}, year = {2025}, }
• (2025). A JWST/MIRI view of the interstellar medium in m83. i. resolved molecular hydrogen properties, star formation, and feedback. ApJ, 987(2), 142. (www)

  @article{ , abstract = {We present a spatially resolved (∼3 pc pixel −1 ) analysis of the distribution, kinematics, and excitation of warm H 2 gas in the nuclear starburst region of M83. Our JWST/MIRI integral field unit spectroscopy reveals a clumpy reservoir of warm H 2 (>200 K) with a mass of ∼2.3 × 10 5 M ⊙ in the area covered by all four Medium Resolution Spectrometer (MRS) channels. We additionally use the [Ne ii ] 12.8 μ m and [Ne iii ] 15.5 μ m lines as tracers of the star formation rate (SFR), ionizing radiation hardness, and kinematics of the ionized interstellar medium (ISM), finding tantalizing connections to the H 2 properties and stellar populations (e.g., broad and blueshifted [Ne ii ] emission coincident with a region with >5 Myr old stellar populations, low SFR, and low H 2 surface density.) Finally, qualitative comparisons to the trove of public, high-spatial-resolution multiwavelength data available on M83 shows that our MRS spectroscopy potentially traces all stages of the process of creating massive star clusters, from the embedded protocluster phase through the dispersion of ISM from stellar feedback.}, archive = {J_ApJ}, author = {Logan H. Jones and Svea Hernandez and Linda J. Smith and Aditya Togi and Tanio Diaz-Santos and Alessandra Aloisi and William Blair and Alec S. Hirschauer and Leslie K. Hunt and Bethan L. James and Nimisha Kumari and Vianney Lebouteiller and Matilde Mingozzi and Lise Ramambason}, doi = {10.3847/1538-4357/adce71}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {142}, shortjournal = {The Astrophys. J.}, title = {A JWST/MIRI view of the interstellar medium in m83. i. resolved molecular hydrogen properties, star formation, and feedback}, volume = {987}, year = {2025}, }
• (2025). Dust-obscured galaxies with broken power-law spectral energy distributions discovered by UNIONS. ApJ, 987(2), 141. (www)

  @article{ , abstract = {We report on the spectral energy distributions (SEDs) of infrared (IR)-bright dust-obscured galaxies (DOGs) with ( i − [22]) AB ≥ 7.0. Using photometry from the deep and wide Ultraviolet Near-Infrared Optical Northern Survey, combined with near-IR (NIR) and mid-IR data from the UKIRT Infrared Deep Sky Survey and the Wide-field Infrared Survey Explorer, we successfully identified 382 DOGs in ∼170 deg 2 . Among them, the vast majority (376 DOGs) were classified into two subclasses: bump DOGs (132/376) and power-law (PL) DOGs (244/376), which are dominated by star formation and active galactic nuclei (AGNs), respectively. Through the SED analysis, we find that roughly half (120/244) of the PL DOGs show broken power-law (BPL) SEDs. The significant red slope from optical to NIR in the SEDs of these “BPL DOGs” probably reflects their large amount of dust extinction. In other words, BPL DOGs are more heavily obscured AGNs, compared to PL DOGs with non-BPL SEDs.}, archive = {J_ApJ}, author = {Taketo Yoshida and Tohru Nagao and Yoshiki Toba and Akatoki Noboriguchi and Kohei Ichikawa and Hendrik Hildebrandt and Naomichi Yutani and Kenneth C. Chambers and Ryo Iwamoto and Seira Kobayashi and Masamune Oguri and Ken Osato and Kohei Shibata and Yuxing Zhong}, doi = {10.3847/1538-4357/add930}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {141}, shortjournal = {The Astrophys. J.}, title = {Dust-obscured galaxies with broken power-law spectral energy distributions discovered by UNIONS}, volume = {987}, year = {2025}, }
• (2025). Self-organized criticality across 13 orders of magnitude in the Solar–Stellar connection. ApJ, 987(2), 140. (www)

  @article{ , abstract = {The observed size distributions of solar and stellar flares are found to be consistent with the predictions of the fractal-diffusive self-organized criticality (FD-SOC) model, which predicts power-law slopes with universal constants of α F = (9/5) = 1.80 for the flux, and α E = (5/3) ≈ 1.67 for the fluence or energy, respectively. In this study, we explore the solar–stellar connection under this aspect, which extends over an unprecedented dynamic range of 13 orders of magnitude between the smallest detected solar nanoflare event ( E min = 10 24 erg) and the largest superflare ( E max = 10 37 erg) on solar-like G-type stars, observed with the Kepler mission. The FD-SOC model predicts a scaling law of L ∝ E (2/9) for the length scale L as a function of the flare energy E , which limits the largest flare size to L max ≲ 0.14 R ⊙ for solar flares, and L stellar ≲ 1.04 R ⊙ for stellar flares on G-type stars. Overall, we conclude that the universality of power laws (and their slopes) is a consequence of SOC properties (fractality, classical diffusion, scale-freeness, volume-flux proportionality), rather than identical physical processes at different wavelengths.}, archive = {J_ApJ}, author = {Markus J. Aschwanden and Carolus J. Schrijver}, doi = {10.3847/1538-4357/addc58}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {140}, shortjournal = {The Astrophys. J.}, title = {Self-organized criticality across 13 orders of magnitude in the Solar–Stellar connection}, volume = {987}, year = {2025}, }
• (2025). Forecasting the fast radio burst population observed through galaxy cluster lenses. ApJ, 987(2), 139. (www)

  @article{ , abstract = {High-redshift fast radio bursts (FRBs) are expected to be extremely powerful probes of our Universe. However, while a significant number of FRBs are expected to exist at high redshift, detecting them has been difficult, with only a handful robustly confirmed at redshifts greater than one. In many other fields, gravitational lensing from galaxy clusters has enabled high-redshift detections by magnifying background sources. In this work we forecast the populations of FRBs expected to be detected by the Canadian Hydrogen Intensity Mapping Experiment (CHIME) and upcoming instrument Canadian Hydrogen Observatory and Radio Transient Detector (CHORD), for blank fields and by lensing through a range of strong lensing galaxy clusters, based on existing, observationally driven cluster models. We find that the presence of a galaxy cluster of mass M ≥ 5 × 10 14 M ⊙ within the detection beam of a transit telescope will approximately double the rate of detected high-redshift ( z ≥ 1 CHIME, z ≥ 2 CHORD) FRBs for that beam. Consequently, we find that knowledge of cluster positions can be used by instruments like CHIME or CHORD in tandem with novel observational strategies to isolate a sample of high-redshift FRBs with ≳50% purity at a rate of ≲3 per year. This would provide a statistically high-redshift sample of mostly gravitationally lensed FRBs that would be ideal candidates for optical follow-up, constraining the FRB–star formation relation and for use in cosmological studies including measuring H 0 , characterising dark matter substructures and probing reionization.}, archive = {J_ApJ}, author = {Mawson W. Sammons and Evan Davies-Velie and Matt Dobbs and Zarif Kader and Seth R. Siegel and Jonathan Sievers}, doi = {10.3847/1538-4357/addc71}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {139}, shortjournal = {The Astrophys. J.}, title = {Forecasting the fast radio burst population observed through galaxy cluster lenses}, volume = {987}, year = {2025}, }
• (2025). The TYPHOON stellar population synthesis survey. II. pushing full spectral fitting to the limit in the nearby grand design barred spiral m83. ApJ, 987(2), 138. (www)

  @article{ , abstract = {We apply population synthesis techniques to analyze TYPHOON long slit spectra of the starburst barred spiral galaxy M83. The analysis covers a central square of 5′ side length. We determine the spatial distribution of dust through the analysis of reddening and extinction, together with star formation rates, ages, and metallicities of young and old stellar populations. For the first time, a spatial one-to-one comparison of metallicities derived from full spectral fitting techniques with those obtained from individual young stellar probes has been carried out. The comparison with blue supergiant stars, young massive star clusters, and super star clusters shows a high degree of concordance when wavelength coverage in the B band is available. The metallicity of the young population is supersolar and does not show a radial metallicity gradient along the investigated part of the disk, in agreement with our chemical evolution model. However, a notable decrease in metallicity is observed in a tightly confined region at the galaxy center, coinciding with circumnuclear orbits. We attribute this to matter infall either from the circumgalactic medium, a dwarf galaxy interloper, or, alternatively, to active-galactic-nucleus-interrupted chemical evolution. We confirm the presence of a dust cavity with a diameter of 260 pc close to the galaxy center. Dust absorption and molecular CO emission are spatially well correlated. We find an anticorrelation between R V , the ratio of dust attenuation to reddening, and the emission strength of molecular species present in photodissociation regions. We confirm our results by using alternative fitting algorithms and stellar libraries.}, archive = {J_ApJ}, author = {Eva Sextl and Rolf-Peter Kudritzki and Fabio Bresolin and Kathryn Grasha and Hye-Jin Park and Qian-Hui Chen and Andrew J. Battisti and Mark Seibert and Barry F. Madore and Jeffrey A. Rich}, doi = {10.3847/1538-4357/addec2}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {138}, shortjournal = {The Astrophys. J.}, title = {The TYPHOON stellar population synthesis survey. II. pushing full spectral fitting to the limit in the nearby grand design barred spiral m83}, volume = {987}, year = {2025}, }
• (2025). Distance to the galactic center 7′ halo from h i absorption. ApJ, 987(2), 137. (www)

  @article{ , abstract = {Using archival data, we have made an H I absorption study of the 7 {}^{{\prime} } halo surrounding the Sgr A complex, observed toward the Galactic center (GC) region. We find strong H I absorption near velocities of −53 km s −1 , which is due to the 3 kpc arm, placing it beyond 5 kpc from us. We further examined the H I absorption properties toward five different parts of the 7 {}^{{\prime} } halo. Absorption by the +50 km s −1 GC cloud is seen toward only three parts of the halo, but not toward the other two regions. Strong emissions in CO and CS are, however, identified toward all the above five parts of the halo by the +50 km s −1 GC molecular cloud. This does show that the 7 {}^{{\prime} } halo is partly behind and partly in front of the 50 km s −1 cloud. To our knowledge, this for the first time clearly shows the 7 {}^{{\prime} } halo to be located at the same distance as the +50 km s −1 molecular cloud, i.e., at the GC region.}, archive = {J_ApJ}, author = {Debangan Maji and Subhashis Roy}, doi = {10.3847/1538-4357/ade05d}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {137}, shortjournal = {The Astrophys. J.}, title = {Distance to the galactic center 7′ halo from h i absorption}, volume = {987}, year = {2025}, }
• (2025). Temporal and structural properties of sunspot small short-living group and large long-living group populations. ApJ, 987(2), 136. (www)

  @article{ , abstract = {We investigate the properties of two types of solar active regions: the small short-living groups (SSGs) and the large long-living groups (LLGs). The combined distribution of areas of active regions is bimodal. When deconvolved, the distributions of each population show a clear presence of cyclic variations with LLG and SSG number varying in phase with each other. We see these in-phase variations and the lognormal distribution of SSG/LLG areas as indications that both types of groups originate from the same mechanism, the solar dynamo action. However, the data also suggest that near-surface convection may play a role. The maxima in the bimodal distribution of sunspot group areas (one for LLG and the other for SSG components) coincide with the typical sizes of the supergranules for the LLG population and mesogranules for the SSG population, which suggests that the large-scale convection patterns may affect the sunspot group formation.}, archive = {J_ApJ}, author = {Yury A. Nagovitsyn and Alexei A. Pevtsov and Aleksandra A. Osipova}, doi = {10.3847/1538-4357/ade13a}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {136}, shortjournal = {The Astrophys. J.}, title = {Temporal and structural properties of sunspot small short-living group and large long-living group populations}, volume = {987}, year = {2025}, }
• (2025). The QPO in RE j1034+396 originates in the hot corona. ApJ, 987(2), 135. (www)

  @article{ , abstract = {RE J1034+396 is one of the few active galactic nuclei (AGNs) with a significant quasiperiodic oscillation (QPO). The QPO has been observed in over 1 Ms of XMM-Newton observations spanning over a decade. We investigate the power spectral density function (PSD) of seven long (∼90 ks) XMM-Newton observations of the AGN RE J1034+396 in two energy bands. The soft (0.3–0.5 keV) band targets emission from the disk, while the hard (2–7 keV) band isolates the primary X-ray continuum emission from the corona. The QPO is significantly detected in the hard band of five of the seven observations. The best-fitting models indicate that the QPO detection in both bands is entirely attributable to the coronal emission with no additional contribution from the disk. This explains the strong coherence between the hard and soft bands at the QPO frequency. The covariance spectrum is consistent with this picture as the variability at QPO frequencies is attributed solely to fluctuations in the hot corona. The time lag as a function of energy is well described by a ∼2000 s intrinsic soft lag, resulting from the disk responding to emission from the corona, that undergoes phase wrapping at approximately the QPO frequency. By demonstrating that in this system the QPO arises in the corona, we provide new insights into the mechanisms generating QPOs.}, archive = {J_ApJ}, author = {Chloe S. Taylor and Dan R. Wilkins and Steven W. Allen}, doi = {10.3847/1538-4357/ade23d}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {135}, shortjournal = {The Astrophys. J.}, title = {The QPO in RE j1034+396 originates in the hot corona}, volume = {987}, year = {2025}, }
• (2025). Dynamics of subsurface flows in solar active regions during the 2024 may storm. ApJ, 987(2), 134. (www)

  @article{ , abstract = {In 2024 May, the Sun exhibited intense magnetic activity, marked by numerous high-intensity flares resulting from the interaction and merging of NOAA active regions (ARs) 13664 and 13668 in the southern hemisphere and AR 13663 in the northern hemisphere. Notably, AR 13664 displayed an extended lifetime, remaining visible after a full solar rotation and continuing to produce significant flaring activity. In this study, we investigate the evolution of subphotospheric plasma flows associated with these ARs during their disk passage using ring-diagram analysis of Solar Dynamics Observatory/Helioseismic and Magnetic Imager Dopplergrams. We analyze flow divergence, vorticity, and kinetic helicity across depths from the surface to 25 Mm, revealing pronounced temporal and depth-dependent variations. Our observations indicate that the majority of flares occur on the days when the Normalized Helicity Gradient Variance, a measure of kinetic helicity spread, peaks or on the following day. Furthermore, we examine the relationship between subsurface flow dynamics and surface magnetic properties of these complex ARs to understand the interaction between them.}, archive = {J_ApJ}, author = {B. Lekshmi and Sushanta Tripathy and Kiran Jain and Alexei Pevtsov}, doi = {10.3847/1538-4357/ade2e3}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {134}, shortjournal = {The Astrophys. J.}, title = {Dynamics of subsurface flows in solar active regions during the 2024 may storm}, volume = {987}, year = {2025}, }
• (2025). The extended GeV gamma-ray emission from HESS j1503-582 with fermi-LAT. ApJ, 987(2), 133. (www)

  @article{ , abstract = {We present the discovery of extended GeV gamma-ray emissions spatially correlated with the unidentified very-high-energy (VHE; > 100 GeV) gamma-ray source HESS J1503-582, utilizing data from Pass 8 of the Fermi Large Area Telescope. The GeV gamma-ray spectrum of HESS J1503-582 is optimally characterized by a power-law model with an index of 1.90, spanning the energy range from 1 GeV to 1 TeV. The gamma-ray emission is spatially coincident with the “Forbidden Velocity Wing” (FVW) 319.8+0.3, a characteristic 21 cm H I line structure that extends to velocities beyond those allowed by Galactic rotation. Taking into account the fact that several FVWs have been identified as old supernova remnants (SNRs), a potential SNR associated with FVW 319.8+0.3 is discussed to explain the multiwavelength data of HESS J1503-582. While both leptonic and hadronic models are capable of accounting for the multiwavelength observations of HESS J1503-582, the cutoff energies and total energy contents of particles challenge the acceleration capability of an old SNR with a slow expanding shell. While a hypothetical OB association or a pulsar halo could potentially account for the high total energy contents of particles and the low magnetic field strength, the absence of any detections of such objects challenges these proposed scenarios.}, archive = {J_ApJ}, author = {Yuliang Xin and Yunfeng Zhang and Xi Liu and Weixiong Ding and Xiaolei Guo}, doi = {10.3847/1538-4357/ade3d0}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {133}, shortjournal = {The Astrophys. J.}, title = {The extended GeV gamma-ray emission from HESS j1503-582 with fermi-LAT}, volume = {987}, year = {2025}, }
• (2025). Cosmic ray mediated thermal fronts in the warm-hot circumgalactic medium. ApJ, 987(2), 132. (www)

  @article{ , abstract = {We investigate the 1D plane-parallel front connecting the warm (10 4 K) and hot (10 6 K) phases of the circumgalactic medium (CGM), focusing on the influence of cosmic rays (CRs) in shaping these transition layers. We find that cosmic rays dictate the thermal balance while other fluxes (thermal conduction, radiative cooling, and gas flow) adjust to compensate. We compute column densities and ratios for the transition-temperature ions Si iv , C iv , O vi , and N v , and compare them with observational data. While most models struggle to simultaneously reproduce the observed Si iv /C iv and C iv /O vi ratios, a subset with intermediate magnetic field strength (e.g., B = 20 μ G) shows overlap with the data, although we make no claims for their uniqueness. These discrepancies suggest that the models perform better at reproducing higher-temperature ions but underestimate the contribution from cooler, photoionized regions. Compared to models without CRs, CR-mediated fronts in sufficiently strong magnetic fields produce broader transition layers and higher ion ratios, indicating that CRs can significantly alter the thermal and ionization structure of the CGM. Our results suggest that CR heating may help explain some observed ion columns under specific conditions, though additional physics may be needed for full agreement with observations.}, archive = {J_ApJ}, author = {Hanjue Zhu and Ellen G. Zweibel and Nickolay Y. Gnedin}, doi = {10.3847/1538-4357/add333}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {132}, shortjournal = {The Astrophys. J.}, title = {Cosmic ray mediated thermal fronts in the warm-hot circumgalactic medium}, volume = {987}, year = {2025}, }
• (2025). Intergalactic absorption confounding circumgalactic observations. ApJ, 987(2), 131. (www)

  @article{ , abstract = {The origin of warm ions in the circumgalactic medium (CGM) surrounding massive galaxies remains a mystery. In this paper, we argue that a significant fraction of the observed warm-ion columns may arise in the intergalactic medium (IGM) surrounding galactic halos. We use a simple spherical collapse model of the dark matter halos and their baryonic content to compute the evolving ion fractions within and outside virial halos. We show that the photoionized IGM may produce a thick blanket of warm ions around the CGM, with column densities comparable to observed values near galaxies, which may therefore contaminate CGM observations. We compare our results with observations, and find that our models qualitatively reproduce the overall O vi columns as well as their trend with the impact parameter and halo mass. We find that the IGM contribution to the observed column depends on galaxy mass and impact parameter, and becomes comparable to the total observed values in galaxies with virial masses exceeding a few times 10 11 M ⊙ , as well as across much of the observed area ( b ≳ 0.5 R vir ) of lower-mass halos. We therefore suggest that theoretical interpretations of CGM-survey observations must consider the possible contribution of the surrounding IGM. We note that more sophisticated (3D) models are required to consider the possibility of nonunity covering fractions suggested by the data. Although our simplified model suggests that it may be possible to kinematically distinguish between CGM and IGM origins through the absorption-line profiles, this distinction is likely unfeasible.}, archive = {J_ApJ}, author = {Itai Bromberg and Kartick C. Sarkar and Haggar Ashkenazy and Orly Gnat and Yuval Birnboim}, doi = {10.3847/1538-4357/add3f8}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {131}, shortjournal = {The Astrophys. J.}, title = {Intergalactic absorption confounding circumgalactic observations}, volume = {987}, year = {2025}, }
• (2025). The relationship between the kinematics of coronal mass ejections and the brightness of the corona. ApJ, 987(2), 130. (www)

  @article{ , abstract = {We present an investigation into an apparent relationship between white-light coronal brightness and the kinematics of flare-associated coronal mass ejections (CMEs). Using a unique data set, known as the Large Angle and Spectrometric Coronagraph Coronal Brightness Index (CBI), we conduct a study that explores the brightness in the lower solar corona and its relationship to the velocity of flare-associated CMEs. We analyze all M- and X-class flares that took place on or near the limbs of the Earth-facing disk of the Sun between 1996 and 2022, determine if these flares are associated with CMEs, and record the projection-corrected velocity of the eruptions if they occurred. Using the CBI data set, we evaluate the brightness in the corona directly overlying the flare source locations between 2.4 and 6.2 solar radii, and we find that above a certain level of coronal brightness, the likelihood of a high-velocity CME significantly decreases. This result implies that coronal brightness could be an important indicator of the kinematics of solar CMEs. We also highlight and discuss the unique nature of active region 12192 in 2014, observing that its unprecedented overlying coronal brightness may be related to the low CME productivity of that region.}, archive = {J_ApJ}, author = {Kelly Victor-French and Karl Battams and Brian E. Wood}, doi = {10.3847/1538-4357/add3fb}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {130}, shortjournal = {The Astrophys. J.}, title = {The relationship between the kinematics of coronal mass ejections and the brightness of the corona}, volume = {987}, year = {2025}, }
• (2025). GRB 241030A: Multicomponent origin of early emission from the photosphere and internal and external shocks. ApJ, 987(2), 129. (www)

  @article{ , abstract = {We present a detailed analysis of the long-duration GRB 241030A detected by Swift. Thanks to the rapid response of the X-Ray Telescope (XRT) and Ultraviolet/Optical Telescope, the strongest part of the prompt emission of GRB 241030A has been well measured simultaneously from the optical to hard X-ray bands. The time-resolved WHITE band emission shows strong variability, largely tracing the activity of the prompt γ -ray emission, suggesting that it may also be produced by internal shocks too. The joint analysis of the XRT and Burst Alert Telescope data reveals the presence of a thermal component with a temperature of a few keV, which can be interpreted as the photosphere radiation, and the upper limit of the Lorentz factor of this region is found to range between approximately 20 and 80. The time-resolved analysis of the initial U -band exposure data yields a very rapid rise (∼ t 5.3 ) with a bright peak reaching 13.6 AB magnitude around 410 s, which is most likely attributed to the onset of the external shock emission. The richness and fineness of early observational data have made this burst unique for studying various radiation mechanisms of γ -ray bursts.}, archive = {J_ApJ}, author = {Qiu-Li Wang and Hao Zhou and Yun Wang and Jia Ren and Samaporn Tinyanont and Dong Xu and Ning-Chen Sun and Johan P. U. Fynbo and Daniele B. Malesani and Jie An and Rungrit Anutarawiramkul and Pathompong Butpa and Shao-Yu Fu and Shuai-Qing Jiang and Xing Liu and Kritsada Palee and Pakawat Prasit and Zi-Pei Zhu and Lu-Yao Jiang and Zhi-Ping Jin and Da-Ming Wei}, doi = {10.3847/1538-4357/add693}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {129}, shortjournal = {The Astrophys. J.}, title = {GRB 241030A: Multicomponent origin of early emission from the photosphere and internal and external shocks}, volume = {987}, year = {2025}, }
• (2025). Discovery of a periodic radio signal from the formerly radio-quiet γ-ray pulsar j0359+5414 with FAST. ApJ, 987(2), 128. (www)

  @article{ , abstract = {In this paper, we report the detection of a periodic radio signal from the radio-quiet γ -ray pulsar PSR J0359+5414, using the Five-hundred-meter Aperture Spherical radio Telescope. This pulsar has a rotational period of 79.42 ms determined in the γ -ray band by the Fermi satellite. Our results show that the period of the radio signal is consistent with that obtained in the γ -ray. The measured dispersion measure value of the pulsar is 89 ± 3 pc cm −3 , with an estimated average flux density of only ∼6 μ Jy. We compare the pulse profiles of the γ -ray and radio pulsars at two phases and find their phases and pulse widths to be similar. The radio emission may originate from the upper regions of the pulsar magnetosphere, near the γ -ray emission zone. This is consistent with the idea that the radio emission in young high- \dot{E} pulsars is produced near the null charge surface and the γ -ray emission zone.}, archive = {J_ApJ}, author = {Ruobin Ding and Zhichen Pan and Ralph P. Eatough and Shuangqiang Wang and Yujie Lian and Shunshun Cao and Renxin Xu and Lei Qian and Tingting Lin and Haiyan Zhang and Shuo Cao}, doi = {10.3847/1538-4357/adda36}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {128}, shortjournal = {The Astrophys. J.}, title = {Discovery of a periodic radio signal from the formerly radio-quiet γ-ray pulsar j0359+5414 with FAST}, volume = {987}, year = {2025}, }
• (2025). A near-infrared search for helium in the superluminous supernova SN 2024ahr. ApJ, 987(2), 127. (www)

  @article{ , abstract = {We present a detailed study of SN 2024ahr, a hydrogen-poor superluminous supernova (SLSN-I), for which we determine a redshift of z = 0.0861. SN 2024ahr has a peak absolute magnitude of M g ≈ M r ≈ −21 mag, rest-frame rise and decline times (50% of peak) of about 40 and 80 days, respectively, and typical spectroscopic evolution in the optical band. Similarly, modeling of the UV/optical light curves with a magnetar spin-down engine leads to typical parameters: an initial spin period of ≈3.3 ms, a magnetic field strength of ≈6 × 10 13 G, and an ejecta mass of ≈9.5 M ⊙ . Due to its relatively low redshift, we obtained a high signal-to-noise ratio near-IR (NIR) spectrum about 43 rest-frame days postpeak to search for the presence of helium. We do not detect any significant feature at the location of the He i λ 2.058 μ m feature and place a conservative upper limit of ∼0.05 M ⊙ on the mass of helium in the outer ejecta. We detect broad features of Mg i λ 1.575 μ m and Mg ii λ 2.136 μ m, which are typical of Type Ic SNe, but with higher velocities. Examining the sample of SLSNe-I with NIR spectroscopy, we find that, unlike SN 2024ahr, these events are generally peculiar. This highlights the need for a large sample of prototypical SLSNe-I with NIR spectroscopy to constrain the fraction of progenitors with helium (Ib-like) and without helium (Ic-like) at the time of explosion, and hence the evolutionary path(s) leading to the rare outcome of SLSNe-I.}, archive = {J_ApJ}, author = {Harsh Kumar and Edo Berger and Peter K. Blanchard and Sebastian Gomez and Daichi Hiramatsu and Moira Andrews and K. Azalee Bostroem and Yize Dong and Joseph Farah and Estefania Padilla Gonzalez and D. Andrew Howell and Curtis McCully and Darshana Mehta and Megan Newsome and Aravind P. Ravi and Giacomo Terreran}, doi = {10.3847/1538-4357/addc67}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {127}, shortjournal = {The Astrophys. J.}, title = {A near-infrared search for helium in the superluminous supernova SN 2024ahr}, volume = {987}, year = {2025}, }
• (2025). M star opacities: The B3Π–X3Δ band system of TiO. ApJ, 987(2), 126. (www)

  @article{ , abstract = {The spectra of titanium monoxide (TiO) are used to classify M stars. TiO experimental cross sections based on a high-resolution emission spectrum recorded with a Fourier transform spectrometer at the National Solar Observatory are used for the analysis of the TiO B 3 Π–X 3 Δ transition ( \gamma ^{\prime} system). The 3–2 and 4–3 vibrational bands are analyzed for the first time, and the analysis of the 2–1 band is revised. The transition dipole moment function from an ab initio calculation is used to calculate the band strengths. These band strengths are used to produce a B 3 Π–X 3 Δ line list for the vibrational levels v ^{\prime} \leqslant 4 and v ″ ≤ 4, suitable for simulation of astronomical spectra.}, archive = {J_ApJ}, author = {Peter F. Bernath and Manish Bhusal and Mirek R. Schmidt}, doi = {10.3847/1538-4357/adde53}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {126}, shortjournal = {The Astrophys. J.}, title = {M star opacities: The B3Π–X3Δ band system of TiO}, volume = {987}, year = {2025}, }
• (2025). Forcing planets to evolve: Interactions between uranus and neptune at late stages of dynamical evolution. ApJ, 987(2), 125. (www)

  @article{ , abstract = {In early solar system numerical simulations, where chaos is a primary driver, it is difficult to explore parameter space in a systematic way. In such simulations, stable configurations are hard to come by, and often require special fine-tuning. In addition, it is infeasible to run suites of well-resolved, realistic simulations with a disk of massive particles to drive planetary evolution where enough particles remain to represent the trans-Neptunian populations to robustly statistically compare with observations. To complement state-of-the-art full N -body simulations, we develop a method to artificially control each planet’s orbital elements independently from each other, which, when carefully applied, can be used to test a wider suite of models. We modify two widely used publicly available N -body integrators: (1) the C code, REBOUND , and (2) the FORTRAN code, Mercury6.2 . We show how the application of specific fictitious forces within numerical integrators can be used to tightly control planetary evolution to more easily explore migration and orbital excitation and damping. This tool allows us to replicate the impact that a massive planetesimal disk would have on the planets, without actually including the massive planetesimals, thus decreasing the chaos and simulation runtime. We demonstrate the utility of this tool by applying it to the coupled orbital evolution of Uranus and Neptune, and show that Neptune’s eccentricity damping and radial outward migration have the appropriate affect on Uranus’ eccentricity.}, archive = {J_ApJ}, author = {Arcelia Hermosillo Ruiz and Ruth Murray-Clay and Kathryn Volk and Rosemary E. Pike}, doi = {10.3847/1538-4357/add6a1}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {125}, shortjournal = {The Astrophys. J.}, title = {Forcing planets to evolve: Interactions between uranus and neptune at late stages of dynamical evolution}, volume = {987}, year = {2025}, }
• (2025). A study of the spectral properties of gamma-ray bursts with main and second bursts. ApJ, 987(2), 124. (www)

  @article{ , abstract = {The origins of the main burst and second burst of gamma-ray bursts (GRBs) and the composition of their jets remain uncertain. To explore this complex subject more thoroughly, we conduct a spectral analysis on 18 GRBs with a main and a second burst observed by Fermi/Gamma-Ray Burst Monitor. First, we employ Bayesian time-resolved spectral analysis to compare the spectral components of the main and the second burst, finding that 83.3% of the main and second bursts contain a thermal component. In 67% of the GRBs, the thermal component gradually decreases from the main to the second burst and the number of spectra exceeding the “synchrotron line of death” is significantly higher in the main burst than in the second burst. Subsequently, we ascertain that for both the main and second bursts, 71.4% and 77.8% evolve in a similar fashion in terms of the low-energy spectral index α and the peak energy E p , respectively. Of the GRBs 50.0% and 72.2% exhibit comparable correlations for flux– α and α – E p , respectively. For flux– E p both the main and second bursts show a positive correlation. Moreover, from the perspective of the temporal evolution of characteristic radii, the transition from the main to the second burst appears to be seamless. Finally, we find that both the main and the second burst follow the same Amati relation and Yonetoku relation. Our analysis strongly indicates that the second burst is a continuation of the main burst and is highly likely to share a common physical origin with it.}, archive = {J_ApJ}, author = {Ze-Lian Du and Zhao-Yang Peng and Jia-Ming Chen and Yue Yin and Ting Li}, doi = {10.3847/1538-4357/add737}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {124}, shortjournal = {The Astrophys. J.}, title = {A study of the spectral properties of gamma-ray bursts with main and second bursts}, volume = {987}, year = {2025}, }
• (2025). Resistive collapse of 2D nonrotating magnetized isothermal toroids: Formation of pseudodisks. ApJ, 987(2), 123. (www)

  @article{ , abstract = {The collapse of singular magnetized toroids is a natural representation of an early phase in star formation, bridging the prestellar and protostellar phases of the collapse of molecular cloud cores. We revisit the collapse study of A. Allen et al., now with explicit nonideal MHD (ohmic diffusivity η ) and higher resolution using a code able to cover a broader range of the magnetization parameter H 0 . Galli–Shu equatorial pseudodisks form for all values of H 0 and η , and the asymptotic central mass growth rate is {\dot{M}}_{* }\sim ({a}^{3}/G)(1+{H}_{0}) , where a is the isothermal sound speed, consistent with previous results and predictions. The explicit ohmic diffusivity makes the field line structure less radial than in previous work, connecting the pseudodisk more effectively to its surroundings. Matter can fall efficiently onto the pseudodisk surfaces, forming oblique shocks, where shock heating and large density gradients raise the possibility of rich astrochemistry. Pseudodisk size and structure are influenced by magnetic diffusivity. Force and velocity ratios were computed to explore the magnetic support within the pseudodisk and its induced reduction in infall velocity. Magnetic diffusivity was measured to control the strength of these effects and their location within the pseudodisk. The dependence of the field line configurations, pseudodisk structure, and velocity ratios on magnetic diffusivity has observable consequences for collapsing envelopes.}, archive = {J_ApJ}, author = {Ya-Chi Wang and Hsien Shang and Ruben Krasnopolsky}, doi = {10.3847/1538-4357/add88a}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {123}, shortjournal = {The Astrophys. J.}, title = {Resistive collapse of 2D nonrotating magnetized isothermal toroids: Formation of pseudodisks}, volume = {987}, year = {2025}, }
• (2025). The density distribution of compressively forced, supersonic turbulence depends on the driving correlation time. ApJ, 987(2), 122. (www)

  @article{ , abstract = {Supersonic turbulence plays a critical role in shaping astrophysical systems, from molecular clouds to the circumgalactic medium. Key properties of this turbulence include the Mach number, driving scale, and nature of the driving mechanism, which can be solenoidal (divergence-free), compressive (curl-free), or a mix of the two. A less studied property is the correlation time of the driving accelerations, τ a .  While this timescale has a minimal impact on solenoidally driven turbulence, we show that it has a strong impact on compressively driven turbulence. Using high-resolution simulations with tracer particles, we analyze the evolution of density fluctuations, focusing on the probability distribution function of the logarithmic density, s , and its rate of change, \frac{ds}{dt}, and the conditional statistics of \frac{ds}{dt} and \frac{{d}^{2}s}{d{t}^{2}} . When the driving correlation time is comparable to the eddy turnover time, τ a ≈ τ e ,  compressive driving leads to the formation of large, low-density voids in which the variance of \frac{ds}{dt} is large. These are directly linked to sustained accelerated expansions, which result in a strong correlation between density and the divergence of the driving acceleration field. In contrast, when τ a ≈ 0.1 τ e , compressive driving does not produce such voids, resulting in a narrower, less skewed distribution. We show using analytical estimates that τ a may be significantly less than τ e in supernova-driven turbulence, highlighting the need to better understand the role of the driving correlation time in shaping the density structure of turbulent astrophysical systems.}, archive = {J_ApJ}, author = {Philipp Grete and Evan Scannapieco and Marcus Brüggen and Liubin Pan}, doi = {10.3847/1538-4357/add936}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {122}, shortjournal = {The Astrophys. J.}, title = {The density distribution of compressively forced, supersonic turbulence depends on the driving correlation time}, volume = {987}, year = {2025}, }
• (2025). Hidden population III descendants in ultrafaint dwarf galaxies. ApJ, 987(2), 121. (www)

  @article{ , abstract = {The elusive properties of the first (Population III or Pop III) stars can be indirectly unveiled by uncovering their true descendants. To this end, we exploit our data-calibrated model for the best-studied ultrafaint dwarf galaxy (UFD), Boötes I, which tracks the chemical evolution (from carbon to zinc) of individual stars from their formation to the present day. We explore the chemical imprint of Pop III supernovae (SNe), with different explosion energies and masses, showing that they leave distinct chemical signatures in their descendants. We find that UFDs are strongly affected by SN-driven feedback, resulting in a very low fraction of metals being retained by their gravitational potential well (<2.5%). Furthermore, the higher the Pop III SN explosion energy, the lower the fraction of metals retained. Thus, the probability of finding descendants of energetic pair-instability SNe is extremely low in these systems. Conversely, UFDs are ideal cosmic laboratories for identifying the fingerprints of less massive and energetic Pop III SNe, through their [X/Fe] abundance ratios. Digging into the literature data for Boötes I, we uncover three hidden candidates for Pop III descendants: one monoenriched and two multienriched. These stars show the chemical signature of Pop III SNe in the mass range [20–65] M ⊙ , spanning a wide range of explosion energies [0.3–10]10 51 erg. In conclusion, candidates for Pop III descendants are hidden in ancient UFDs, but those monoenriched by a single Pop III SN are extremely rare. Thus, self-consistent models such as the one presented here are required to uncover these precious fossils and probe the properties of the first Pop III SNe.}, archive = {J_ApJ}, author = {Martina Rossi and Stefania Salvadori and Ása Skúladóttir and Irene Vanni and Ioanna Koutsouridou}, doi = {10.3847/1538-4357/add5e9}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {121}, shortjournal = {The Astrophys. J.}, title = {Hidden population III descendants in ultrafaint dwarf galaxies}, volume = {987}, year = {2025}, }
• (2025). Using simulation-based inference on tidally perturbed dwarf galaxies: The dynamics of NGC 205. ApJ, 987(2), 120. (www)

  @article{ , abstract = {We develop a novel approach to performing precision inference on tidally perturbed dwarf galaxies. We use a Bayesian inference framework of implicit likelihood inference, previously applied mainly in the field of cosmology, based on forward simulation, data compression, and likelihood emulation with neural density estimators. We consider the case of NGC 205, a satellite of M31. NGC 205 exhibits an S-shape in the mean line-of-sight velocity along its semimajor spatial axis, suggestive of tidal perturbation. We demonstrate that this velocity profile can be qualitatively reproduced even if NGC 205 was in a spherically symmetric and isotropic state before its most recent pericenter passage. We apply our inference method to mock data and show that the precise shape of a perturbed satellite’s sky-projected internal velocity field, mapped across its entire face, can be highly informative of both its orbit and total mass density profile, even in the absence of proper motion information. For NGC 205 specifically, our method is hampered because the available data only covers a line along its semimajor axis. This shortcoming could be addressed with another round of observations.}, archive = {J_ApJ}, author = {Axel Widmark and Kathryn V. Johnston}, doi = {10.3847/1538-4357/add887}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {120}, shortjournal = {The Astrophys. J.}, title = {Using simulation-based inference on tidally perturbed dwarf galaxies: The dynamics of NGC 205}, volume = {987}, year = {2025}, }
• (2025). Polarization properties of energetic pulsars at meterwavelengths. ApJ, 987(2), 119. (www)

  @article{ , abstract = {Polarization behavior shows a transition in the pulsar population, where energetic sources with higher spin-down energy loss, \dot{E}\gt 1{0}^{34} erg s −1 , often have fractional linear polarization ( L / I ) close to 100%, while below this range L / I is usually lower than 50%. The polarization behavior has been primarily studied at higher frequencies above 1 GHz, and in this work, we explore the single-pulse polarization behavior in pulsars with \dot{E}\gt 5\,\times 1{0}^{33} erg s −1 at a lower frequency range of 300–750 MHz. The polarization behavior can be divided into two categories, the first with L / I > 70% where the polarization position angle (PPA) follows a single track, and a second group with L / I <  70% and scattered PPA behavior with or without orthogonal modes. However, there are some single pulses in the first category that also have lower L / I and exhibit the presence of two polarization modes along orthogonal tracks. The radio emission in pulsars arises due to coherent curvature radiation (CCR) from charge bunches, which develops due to nonlinear instabilities in the pulsar plasma forming charge separated envelope solitons. The CCR excites orthogonally polarized X and O modes oriented perpendicular and parallel to the magnetic field line planes, which detach in the plasma and propagate independently. The O mode is 7 times stronger than the X mode but gets damped in the medium. We show that incoherent mixing of the X and O modes with different levels of damping can reproduce the observed polarization features in the energetic pulsar population.}, archive = {J_ApJ}, author = {Dipanjan Mitra and Rahul Basu and George I. Melikidze}, doi = {10.3847/1538-4357/addab1}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {119}, shortjournal = {The Astrophys. J.}, title = {Polarization properties of energetic pulsars at meterwavelengths}, volume = {987}, year = {2025}, }
• (2025). The central engine of low-luminosity radio galaxy 3C 270 (NGC 4261). ApJ, 987(2), 118. (www)

  @article{ , abstract = {We present the polarization spectra of the nucleus of 3C 270. We confirm that the polarization angles of both the continuum and the emission lines are close to perpendicular to the jet direction after careful correction of interstellar polarization, which indicates polar scattering. The Stokes flux spectrum resembles the total flux spectrum, with no need for a broad component from the broad-line region. Over 94% of a sample of Seyfert I broad-line profiles would be significantly detected if present in our polarized flux spectrum. We favor the hypothesis that we are observing the continuum including any contribution from radiatively inefficient accretion flow and beamed synchrotron instead of a big blue bump, as well as the innermost narrow-line region, through reflection. This makes 3C 270 the third known case, after NGC 4258 and Centaurus A, where only narrow lines (and the continuum, if present) are scattered, with no evidence of an underlying big blue bump.}, archive = {J_ApJ}, author = {Chengzhang Jiang and Robert Antonucci and J. A. Acosta-Pulido and Patrick Ogle}, doi = {10.3847/1538-4357/addc5a}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {118}, shortjournal = {The Astrophys. J.}, title = {The central engine of low-luminosity radio galaxy 3C 270 (NGC 4261)}, volume = {987}, year = {2025}, }
• (2025). Intriguing nature of AM her–type candidate CXOU j204734.8+300105. ApJ, 987(2), 117. (www)

  @article{ , abstract = {The detection and characterization of periodic X-ray signals are crucial for identifying new compact objects and studying the mechanisms powering their emission. We report on the timing and spectral variability of CXOU J204734.8+300105, a proposed eclipsing polar-type cataclysmic variable (CV) candidate. This source has been observed once with Chandra and twice with XMM-Newton, revealing several intriguing and conflicting features in its X-ray emission. The Chandra observation showed a periodicity of ∼6000 s with an eclipse-like feature. The X-ray light curve from the 2017 XMM-Newton observation showed a period of ∼2000 s without any apparent eclipse, while the simultaneous optical light curve from the Optical Monitor showed a period of ∼6000 s. This variability raises questions about the true nature of the source. Spectral analysis indicates a multicomponent emission and emission lines due to Fe. The spectral characteristics are consistent with those observed in other CV systems. Additionally, we identified optical and near-infrared counterparts from various catalogues. Our findings suggest a dynamic and evolving accretion environment of CXOU J204734.8+300105.}, archive = {J_ApJ}, author = {Rahul Sharma and Chetana Jain and Biswajit Paul and Anjan Dutta and Vikram Rana}, doi = {10.3847/1538-4357/addc5b}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {117}, shortjournal = {The Astrophys. J.}, title = {Intriguing nature of AM her–type candidate CXOU j204734.8+300105}, volume = {987}, year = {2025}, }
• (2025). Long-duration nonthermal motions in the supra-arcade and loop-top region during an eruptive solar flare. ApJ, 987(2), 116. (www)

  @article{ , abstract = {Solar flares are widely accepted to be powered by magnetic reconnection that involves complex dynamics in various scales. The flare supra-arcade and loop-top region, directly impacted by fast reconnection downflows, contains a wealth of microscopic dynamics, which are, however, difficult to resolve in imaging. We present simultaneous spectroscopic and imaging observations of hot flaring plasma above the loop tops by the Interface Region Imaging Spectrograph (IRIS) and Solar Dynamics Observatory/Atmospheric Imaging Assembly. IRIS continuously observed high-temperature Fe xxi 1354.08 Å spectral emissions throughout the long-duration gradual phase of the X-class flare. We found weak Doppler blueshifts near the loop-top region, indicative of bulk plasma motions from chromospheric evaporation based on the three-dimensional flare loop orientation. Strong nonthermal velocities are detected at the bottom of the flare supra-arcade fan/plasma sheet, suggestive of the presence of turbulence in the flare current sheet region. In addition, disorganized nonthermal plasma motions are constantly detected until the very end of the flare, indicating irregular unresolved plasma flows in the cusp and loop-top region. The spatial and temporal evolution of spectral parameters follow the dynamics resulting from ongoing magnetic reconnection during the prolonged gradual phase. The long-lasting nonthermal plasma motions may contribute to the high and steady temperature of flaring plasmas above flare loops.}, archive = {J_ApJ}, author = {Tingyu Gou and Katharine K. Reeves}, doi = {10.3847/1538-4357/addd20}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {116}, shortjournal = {The Astrophys. J.}, title = {Long-duration nonthermal motions in the supra-arcade and loop-top region during an eruptive solar flare}, volume = {987}, year = {2025}, }
• (2025). Falling threads during solar filament eruptions. ApJ, 987(2), 115. (www)

  @article{ , abstract = {Mass drainage is frequently observed in solar filaments. During filament eruptions, falling material most likely flows along magnetic field lines, which may provide important clues for the magnetic structures of filaments. Here we study three filament eruptions exhibiting significant mass draining, often manifested as falling threads at a constant speed ranging between 30 and 300 km s −1 . We found that most of the falling material lands onto the hooked segments of flare ribbons, only a small fraction lands inside the hooks, and almost none lands onto the straight segments of ribbons. Based on these observations we surmise that before eruptions most of the filament mass is entrained by field lines threading the quasi-separatrix layers (QSLs), which wrap around the filament field and whose footpoints are mapped by the hooked ribbons, and that the magnetic reconnection involving these field lines is the major cause of the mass drainage during eruptions. Additionally, the light curves of the hooked ribbons suggest that during eruptions the earlier (later) QSL boundary of filaments is threaded by mass-loaded (depleted) field lines. By assuming that the constant-speed motion is due to a drag force balancing the gravity, we proposed a simplified analytical model to estimate the density contrast of the falling material. The estimated density contrast is then fed into a numerical model, in which filament threads fall along vertical magnetic field lines through a gravitationally stratified atmosphere. The resultant falling speeds, however, are short of observed values, which calls for further investigations.}, archive = {J_ApJ}, author = {Yidian Wu and Rui Liu and Runbin Luo and Wensi Wang}, doi = {10.3847/1538-4357/adddaf}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {115}, shortjournal = {The Astrophys. J.}, title = {Falling threads during solar filament eruptions}, volume = {987}, year = {2025}, }
• (2025). SiO v = 1 j = 5 → 4 maser emission from the root of the “Water fountain” source w 43A. ApJ, 987(2), 114. (www)

  @article{ , abstract = {We report here the first mapping of SiO v = 1 J = 5 → 4 maser emission toward the “water fountain” source W 43A in order to explore the central stellar system driving the collimated, bipolar, fast jet. The maser source has a systemic line-of-sight velocity consistent with that of CO J = 2 → 1 emission tracing the jet within ∼2 km s −1 but a velocity gradient opposite that of the jet. The dynamical center of the maser source is located within ∼10 mas (or ∼20 au) of the brightness peak of the central 1.3 mm continuum emission. The spatiokinematic properties of the SiO J = 5 → 4 and J = 1 → 0 masers suggest that they are associated with the root of a slow (10 km s −1 < V outflow << 100 km s −1 ) outflow with a large opening angle, and the central stellar system is contained within the inner maser region (∼20 au) during a possible common-envelope evolution.}, archive = {J_ApJ}, author = {Hiroshi Imai and Takeshi Hoshino and Daniel Tafoya and José F. Gómez and Jun-ichi Nakashima and Gabor Orosz}, doi = {10.3847/1538-4357/adde4e}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {114}, shortjournal = {The Astrophys. J.}, title = {SiO v = 1 j = 5 → 4 maser emission from the root of the “Water fountain” source w 43A}, volume = {987}, year = {2025}, }
• (2025). Exploring the future of soft X-ray polarimetry: The capabilities of the REDSoX instrument for X-ray dim isolated neutron star and magnetar studies. ApJ, 987(2), 113. (www)

  @article{ , abstract = {X-ray polarimetry offers a unique window into neutron star physics and can provide answers to questions that cannot otherwise be probed. The upcoming Rocket Experiment Demonstration of a Soft X-ray Polarimeter (REDSoX) sounding rocket mission will be the first experiment equipped with a detector able to explore polarized X-rays below 1 keV, observing in the 0.2–0.4 keV range. Although REDSoX will only be capable of short, one-off observations, it will crucially test the instrument performance. In this paper we investigate how a fully fledged orbital mission with a longer lifetime, based on an instrument design similar to REDSoX, will allow us to study thermal emission from X-ray dim isolated neutron stars (XDINSs) and magnetars, probing their magnetic fields and the physics of their outer surface layers, including vacuum effects and quantum electrodynamics (QED) mode conversion at the vacuum resonance. We discuss the potentially observable features for promising values of the star’s surface temperature, magnetic field, and viewing geometry. Assuming emission from the whole surface, we find that, for a source with a magnetic field B = 5 × 10 13 G and surface temperature T ≈ 10 7 K, the instrument can resolve a proton cyclotron absorption feature in the spectrum with high significance when collecting ≈25,000 counts across a single observation. Similarly, for a source with B = 10 14 G and T ≈ 10 7 K, a switch in the dominant polarization mode, caused by mode conversion at the vacuum resonance, can be detected by collecting ≈25,000 counts, allowing for a long-sought observational test of the presence of QED effects. We then present two case studies for XDINS targets: RX J1856.5–3754 and RX J0720.4–3125.}, archive = {J_ApJ}, author = {Ruth M. E. Kelly and Herman L. Marshall and Silvia Zane and Nabil Brice and Swati Ravi and Roberto Turolla and Roberto Taverna and Denis González-Caniulef}, doi = {10.3847/1538-4357/adde58}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {113}, shortjournal = {The Astrophys. J.}, title = {Exploring the future of soft X-ray polarimetry: The capabilities of the REDSoX instrument for X-ray dim isolated neutron star and magnetar studies}, volume = {987}, year = {2025}, }
• (2025). Multiwavelength and environmental properties of variability selected low-luminosity active galactic nuclei. ApJ, 987(2), 112. (www)

  @article{ , abstract = {We present the multiwavelength and environmental properties of 37 variability-selected active galactic nuclei (AGNs), including 30 low-luminosity AGNs (LLAGNs), using a high cadence time-domain survey (All-Sky Automated Survey for SuperNovae) from a spectroscopic sample of 1218 nearby bright galaxies. We find that high-cadence time-domain surveys uniquely select LLAGNs that do not necessarily satisfy other AGN selection methods, such as X-ray, mid-IR, or BPT methods. In our sample, 3% of them pass the mid-infrared color based AGN selection, 18% pass the X-ray luminosity based AGN selection, and 60% pass the BPT selection. This result is supported by two other LLAGN samples from high-cadence time-domain surveys of the Transiting Exoplanet Survey Satellite and Palomar Transient Factory, suggesting that the variability selection method from well-sampled light curves can find AGNs that may not be discovered otherwise. These AGNs can have moderate to small variability amplitudes from the accretion disk, but many of them lack strong corona, emission lines from the central engine, or accretion power to dominate the mid-IR emission. The X-ray spectra of a subsample of bright sources are consistent with a power-law model. Upon inspecting the environments of our sample, we find that LLAGNs are more common in denser environments of galaxy clusters in contrast with the trend established in the literature for luminous AGNs at low redshifts, which is broadly consistent with our analysis result for luminous AGNs limited by a smaller sample size. This contrast in environmental properties between LLAGN and luminous AGNs suggests that LLAGNs may have different trigger mechanisms.}, archive = {J_ApJ}, author = {Heechan Yuk and Xinyu Dai and Marko Mićić}, doi = {10.3847/1538-4357/addf42}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {112}, shortjournal = {The Astrophys. J.}, title = {Multiwavelength and environmental properties of variability selected low-luminosity active galactic nuclei}, volume = {987}, year = {2025}, }
• (2025). Improving optical photo-z constraints for dusty star-forming galaxies using submillimeter-based priors. ApJ, 987(2), 111. (www)

  @article{ , abstract = {Photometric redshifts (photo- z ’s) provide an efficient alternative to spectroscopic redshifts, enabling redshift estimation for large galaxy samples. However, traditional photo- z methods primarily rely on optical and near-infrared (OIR) photometry, which can struggle with dusty star-forming galaxies that are often faint in the OIR but bright at far-infrared (FIR) and millimeter wavelengths. We present a method for incorporating FIR-to-millimeter photometry as a prior within standard OIR-based photo- z frameworks, explicitly folding in the observed empirical relationship between total infrared luminosity and dust temperature. This approach is particularly suitable for wide-area surveys, such as those anticipated with the Euclid satellite or Rubin Observatory, where OIR photo- z ’s can be complemented with longer-wavelength data to help with the dustiest and highest star-forming galaxies. Applying this method to the Herschel Astrophysical Terahertz Large Area Survey (or H-ATLAS) catalog, which combines FIR photometry from Herschel-SPIRE with OIR observations, we achieve a threefold reduction in catastrophic outliers compared to traditional OIR-based photo- z techniques, demonstrating its utility for improving redshift estimates in FIR-bright galaxies.}, archive = {J_ApJ}, author = {Pouya Tanouri and Ryley Hill and Douglas Scott and Edward L. Chapin}, doi = {10.3847/1538-4357/ade0af}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {111}, shortjournal = {The Astrophys. J.}, title = {Improving optical photo-z constraints for dusty star-forming galaxies using submillimeter-based priors}, volume = {987}, year = {2025}, }
• (2025). Heat-flux instabilities of regularized kappa distributed strahl electrons resolved with ALPS. ApJ, 987(2), 110. (www)

  @article{ , abstract = {The fluid behavior of the solar wind is affected by the heat flux carried by the suprathermal electron populations, especially the electron strahl (or beam) that propagates along the magnetic field. In turn, the electron strahl cannot be stable, and in the absence of collisions, its properties are regulated mainly by self-generated instabilities. This paper approaches the description of these heat-flux instabilities in a novel manner using regularized Kappa distributions (RKDs) to characterize the electron strahl. RKDs conform to the velocity distributions with suprathermal tails observed in situ, and at the same time allow for consistent macromodeling, based on their singularity-free moments. In contrast, the complexity of RKD models makes the analytical kinetic formalism complicated and still inaccessible, and therefore, here heat-flux instabilities are resolved using the advanced solver ALPS. Two primary types of instabilities emerge depending on plasma conditions: the whistler and firehose heat-flux instabilities. The solver is successfully tested for the first time for such instabilities by comparison with previous results for standard distributions, such as Maxwellian and Kappa. Moreover, the new RKD results show that idealized Maxwellian models can overrate or underestimate the effects of these instabilities, and also show differences from those obtained for the standard Kappa, which, for instance, underestimate the firehose heat-flux growth rates.}, archive = {J_ApJ}, author = {Dustin L. Schröder and Marian Lazar and Rodrigo A. López and Horst Fichtner}, doi = {10.3847/1538-4357/ade0c0}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {110}, shortjournal = {The Astrophys. J.}, title = {Heat-flux instabilities of regularized kappa distributed strahl electrons resolved with ALPS}, volume = {987}, year = {2025}, }
• (2025). Deep neutral hydrogen observations of the early-type galaxy NGC 2768: Collided by a newly discovered satellite galaxy?. ApJ, 987(2), 109. (www)

  @article{ , abstract = {We present the results of a deep neutral hydrogen (H i ) observation of the early-type galaxy NGC 2768 using the Five-hundred-meter Aperture Spherical radio Telescope (FAST). Leveraging the high sensitivity of FAST, we discover an extended gas envelope around NGC 2768. The total H i mass is measured to be 8.1 × 10 8 M ⊙ , representing a magnitude increase compared to previous Westerbork Synthesis Radio Telescope (WSRT) studies. A position-velocity (PV) diagram indicates the envelope mainly involves two components: an H i disk of NGC 2768 and a newly discovered satellite galaxy without detectable counterparts in currently deep optical surveys. The center of the gas disk is misaligned with the optical disk of NGC 2768, with more gas redshifted, indicating it has been disturbed. Our study indicates NGC 2768 is currently undergoing a transition from a spiral galaxy to an S0. Previous deep WSRT observations reveal two dense clumps (named “Clumps A” and “Clump B” throughout this paper) in the center of the envelope. We find Clump A corresponds to the densest part of the disk, while Clump B might be a newly discovered satellite galaxy that probably collided with NGC 2768 about 0.38 Gyr ago. We also find tidal interactions between Clump B and PGC 2599651, NGC 2768, and UGC 4808. Based on these new findings, we finally analyze the hierarchical accretion history of NGC 2768.}, archive = {J_ApJ}, author = {Nai-Ping Yu and Ming Zhu and Jin-Long Xu and Chuan-Peng Zhang and Xiao-Lan Liu and Peng Jiang}, doi = {10.3847/1538-4357/ade30b}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {109}, shortjournal = {The Astrophys. J.}, title = {Deep neutral hydrogen observations of the early-type galaxy NGC 2768: Collided by a newly discovered satellite galaxy?}, volume = {987}, year = {2025}, }
• (2025). Searching for radio pulses from radio-quiet gamma-ray pulsars with FAST. ApJ, 987(2), 108. (www)

  @article{ , abstract = {We present periodicity and single-pulse searches at 1250 MHz for 22 “radio-quiet” gamma-ray pulsars, conducted using the Five-hundred-meter Aperture Spherical Radio Telescope. For PSR J1813−1246, we successfully detected pulsed signals with a spin period of 48.08 ms and a dispersion measure of 209.85 pc cm −3 , consistent with the spin period measured at gamma-ray wavelengths. The estimated flux density is approximately 9 μ Jy. For the remaining 21 sources, no radio emission was detected, with flux density upper limits of several μ Jy. The capability to detect pulsars with such low flux densities provides the opportunity to determine if and how these faint sources differ from much radio-brighter pulsars.}, archive = {J_ApJ}, author = {S. Q. Wang and S. Dai and N. Wang and A. Zic and G. Hobbs and D. Li and R. B. Ding and L. Peng and Z. C. Pan and S. B. Zhang}, doi = {10.3847/1538-4357/ade441}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {108}, shortjournal = {The Astrophys. J.}, title = {Searching for radio pulses from radio-quiet gamma-ray pulsars with FAST}, volume = {987}, year = {2025}, }
• (2025). Fast transitions of X-ray variability in the neutron star low-mass X-ray binary cygnus X-2. ApJ, 987(2), 107. (www)

  @article{ , abstract = {We present a spectral-timing analysis of two NICER observations of the weakly magnetized neutron star low-mass X-ray binary Cygnus X-2. During these observations, we detect a rapid transition from a narrow 50 Hz horizontal-branch oscillation (HBO) to a broad 5 Hz normal-branch oscillation (NBO), accompanied by an increase in source flux and a decrease in spectral hardness. Thanks to the large effective area of NICER, we are able to conduct a detailed comparison of the spectra associated with different types of quasiperiodic oscillations (QPOs) on short timescales. By fitting the spectra with a model that includes a disk and Comptonization components plus two emission lines, we find that the parameters of the disk component do not change significantly during the transition. However, assuming a fixed electron temperature, the optical depth of the Comptonization component decreases significantly. This drop in optical depth may be attributed to the expansion of the boundary layer (BL) or spreading layer (SL). In addition, we find that the rms spectra for both the HBOs and NBOs are hard, suggesting that the BL or SL is driving the variability. We discuss the potential physical origin of the different types of QPOs.}, archive = {J_ApJ}, author = {Liang Zhang and Mariano Méndez and Hua Feng and Diego Altamirano and Zi-xu Yang and Qing-chang Zhao and Shuang-Nan Zhang and Lian Tao and Yue Huang and Xiang Ma and Shu-mei Jia and Ming-yu Ge and Li-Ming Song and Jin-Lu Qu and Shu Zhang}, doi = {10.3847/1538-4357/ade4ca}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {107}, shortjournal = {The Astrophys. J.}, title = {Fast transitions of X-ray variability in the neutron star low-mass X-ray binary cygnus X-2}, volume = {987}, year = {2025}, }
• (2025). Quasars can signpost supermassive black hole binaries. ApJ, 987(2), 106. (www)

  @article{ , abstract = {Supermassive black holes (SMBHs) are found in the centers of massive galaxies, and galaxy mergers should eventually lead to SMBH mergers. Quasar activity has long been associated with galaxy mergers, so here we investigate if supermassive black hole binaries (SMBHBs) are preferentially found in quasars. Our multimessenger investigation folds together a gravitational-wave background signal from NANOGrav, a sample of periodic active galactic nucleus candidates from the Catalina Real-Time Transient Survey, and a quasar mass function, to estimate an upper limit on the fraction of quasars which could host an SMBHB. We find at 95% confidence that quasars are at most 5 times as likely to host an SMBHB as a random galaxy. Pulsar timing arrays may therefore be more likely to find SMBHBs by prioritizing quasars over a random selection of galaxies in their searches.}, archive = {J_ApJ}, author = {J. Andrew Casey-Clyde and Chiara M. F. Mingarelli and Jenny E. Greene and Andy D. Goulding and Siyuan Chen and Jonathan R. Trump}, doi = {10.3847/1538-4357/adce05}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {106}, shortjournal = {The Astrophys. J.}, title = {Quasars can signpost supermassive black hole binaries}, volume = {987}, year = {2025}, }
• (2025). Quantum machine learning for identifying transient events in X-ray light curves. ApJ, 987(2), 105. (www)

  @article{ , abstract = {We investigate whether a novel method of quantum machine learning can identify anomalous events in X-ray light curves as transient events and apply it to detect such events from the XMM-Newton 4XMM-DR14 catalog. The architecture we adopt is a quantum version of long short-term memory (LSTM) where some fully connected layers are replaced with quantum circuits. LSTM, making predictions based on preceding data, allows for the identification of anomalies by comparing predicted and actual time-series data. The necessary training data are generated by simulating active-galactic-nucleus-like light curves as these events would be a significant population in the XMM-Newton catalog. Additional anomaly data used to assess trained quantum LSTM (QLSTM) models are produced by adding flare-like quasiperiodic eruptions to the training data. Comparing various aspects of the performances of the quantum and classical LSTM (CLSTM) models, we find that QLSTM models incorporating quantum superposition and entanglement slightly outperform the CLSTM model in expressive power, accuracy, and true-positive rate. The highest-performance QLSTM model is then used to identify transient events in 4XMM-DR14. Out of 40,154 light curves in the 0.2–12 keV band, we detect 113 light curves with anomalies, or transient event candidates. This number is ≈1.3 times that of anomalies detectable with the CLSTM model. By utilizing SIMBAD and four wide-field survey catalogs made by ROSAT, SkyMapper, Pan-STARRS, and the Wide-field Infrared Survey Explorer, no possible counterparts are found for 12 detected anomalies.}, archive = {J_ApJ}, author = {Taiki Kawamuro and Shinya Yamada and Shigehiro Nagataki and Shunji Matsuura and Yusuke Sakai and Satoshi Yamada}, doi = {10.3847/1538-4357/adda43}, journal = {The Astrophysical Journal}, month = {7}, number = {2}, pages = {105}, shortjournal = {The Astrophys. J.}, title = {Quantum machine learning for identifying transient events in X-ray light curves}, volume = {987}, year = {2025}, }
• (2025). Erratum: “Asymptotic normalization coefficient investigation of the 17O(d, p) transfer for astrophysical application to the 17O(n, α)14C reaction at low energies” (2024, ApJ, 975, 32). ApJ, 987(1), 104. (www)

  @article{ , archive = {J_ApJ}, author = {G. L. Guardo and L. Lamia and J. P. Fernández-García and S. Piskor and M. La Cognata and G. D’Agata and S. Palmerini and D. Vescovi and V. Burjan and R. J. deBoer and V. Kroha and D. Lattuada and J. Mrazek and A. A. Oliva and R. G. Pizzone and G. G. Rapisarda and S. Romano and M. L. Sergi and R. Spartá and A. Tumino}, doi = {10.3847/1538-4357/ade145}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {104}, shortjournal = {The Astrophys. J.}, title = {Erratum: “Asymptotic normalization coefficient investigation of the 17O(d, p) transfer for astrophysical application to the 17O(n, α)14C reaction at low energies” (2024, ApJ, 975, 32)}, volume = {987}, year = {2025}, }
• (2025). Erratum: “The farthest quasar mini-broad absorption line outflow from its central source: Very large Telescope/UVES observation of SDSS j0242+0049” (2022, ApJ, 927, 176). ApJ, 987(1), 103. (www)

  @article{ , archive = {J_ApJ}, author = {Doyee Byun and Nahum Arav and Patrick B. Hall}, doi = {10.3847/1538-4357/ade2de}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {103}, shortjournal = {The Astrophys. J.}, title = {Erratum: “The farthest quasar mini-broad absorption line outflow from its central source: Very large Telescope/UVES observation of SDSS j0242+0049” (2022, ApJ, 927, 176)}, volume = {987}, year = {2025}, }
• (2025). Erratum: “Dynamics of star cluster formation: The effects of ongoing star formation and stellar feedback” (2025, ApJ, 984, 75). ApJ, 987(1), 102. (www)

  @article{ , archive = {J_ApJ}, author = {Jeremy Karam and Michiko S. Fujii and Alison Sills}, doi = {10.3847/1538-4357/ade5b1}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {102}, shortjournal = {The Astrophys. J.}, title = {Erratum: “Dynamics of star cluster formation: The effects of ongoing star formation and stellar feedback” (2025, ApJ, 984, 75)}, volume = {987}, year = {2025}, }
• (2025). Covariant guiding center equations for charged particle motions in general relativistic spacetimes. ApJ, 987(1), 101. (www)

  @article{ , abstract = {Low-density plasmas in curved spacetimes, such as those found in accretion flows around black holes, are challenging to model from first principles, owing to the large separation in scale between the characteristic scales of the microscopic processes and large mean free paths comparable to the system sizes. Kinetic approaches become necessary to capture the relevant physics but lack the dynamic range to model the global characteristics of the systems. In this paper, we develop new covariant guiding center equations of motion for charges in general relativistic spacetimes that are computationally tractable. We decompose the particle motion into a fast gyration, which we integrate analytically, and a slow drift of the guiding center, which can be solved numerically. We derive covariant conservation laws for the motions of the guiding centers and show, through several limiting cases, that the equations contain all known drift mechanisms. Finally, we present the general relativistic expressions for the various drift velocities in Schwarzschild spacetimes.}, archive = {J_ApJ}, author = {Tyler Trent and Karin Roley and Matthew Golden and Dimitrios Psaltis and Feryal Özel}, doi = {10.3847/1538-4357/adbca8}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {101}, shortjournal = {The Astrophys. J.}, title = {Covariant guiding center equations for charged particle motions in general relativistic spacetimes}, volume = {987}, year = {2025}, }
• (2025). The robust detection and spatial distribution of acetaldehyde in orion KL: Atacama large millimeter/submillimeter array observations and chemical modeling. ApJ, 987(1), 100. (www)

  @article{ , abstract = {Despite the organic molecule inventory detected in the Orion Kleinmann–Low Nebula (Orion KL), acetaldehyde (CH 3 CHO)—one of the most ubiquitous interstellar aldehydes—has not been firmly identified with millimeter-wave interferometry. We analyze extensive Atacama Large Millimeter/submillimeter Array archival data sets (142–355 GHz) to search for acetaldehyde, revealing two distinct acetaldehyde emission peaks and one component with more complex kinematic structures. One peak aligns with MF10/IRc2, where emissions of other O-bearing complex organic molecules are rarely reported, while the other is coincident with the ethanol peak in the southwest region of the hot core. The MF10/IRc2 detection suggests unique chemistry, possibly influenced by repeated heating events. In contrast, codetection with ethanol indicates an ice origin and suggests a potential chemical relationship between the two species. We determine acetaldehyde column densities and kinetic temperatures toward these two peaks under local thermodynamic equilibrium assumptions and compare its distribution with ethanol and other molecules that have an aldehyde (HCO) group, such as methyl formate, glycolaldehyde, and formic acid. Toward the ethanol peak, the observed abundance ratios between HCO-containing species are analyzed using a chemical model. The model suggests two key points: (1) the destruction of ethanol to form acetaldehyde in the ice may contribute to the observed correlation between the two species; and (2) a long cold-collapse timescale and a methyl formate binding energy similar to or lower than water are needed to explain the observations. The relative abundance ratios obtained from the model are highly sensitive to the assumed kinetic temperature, which accounts for the high spatial variability of the aldehyde ratios observed toward Orion KL.}, archive = {J_ApJ}, author = {Miwha Jin and Anthony J. Remijan and Robin T. Garrod and Giseon Baek and Martin Cordiner and Steven Charnley and Eric Herbst and Jeong-Eun Lee}, doi = {10.3847/1538-4357/adc4dd}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {100}, shortjournal = {The Astrophys. J.}, title = {The robust detection and spatial distribution of acetaldehyde in orion KL: Atacama large millimeter/submillimeter array observations and chemical modeling}, volume = {987}, year = {2025}, }
• (2025). Local analogs of primordial galaxies: In search of intermediate-mass black holes with JWST NIRSpec. ApJ, 987(1), 99. (www)

  @article{ , abstract = {Local low-metallicity galaxies with signatures of possible accretion activity are ideal laboratories in which to search for the lowest-mass black holes and study their impact on the host galaxy. Here we present the first JWST NIRSpec IFS observations of SDSS J120122.30+021108.3, a nearby ( z = 0.00354) extremely metal-poor dwarf galaxy with no optical signatures of accretion activity but identified by the Wide-field Infrared Survey Explorer to have red mid-infrared (MIR) colors consistent with active galactic nuclei (AGNs). We identify over 100 lines between ∼1.7 and 5.2 μ m, an unresolved nuclear continuum source with an extremely steep spectral slope consistent with hot dust from an AGN ( F ν ≈ ν −1.5 ), and a plethora of H i , He i , and H 2 lines, with no lines from heavier elements, CO or ice absorption features, or polycyclic aromatic hydrocarbons (PAHs). While the bright central unresolved source (≲5 pc) is suggestive of an AGN, there are no He ii lines or coronal lines identified in the spectrum, and, importantly, there is no evidence that the radiation field is harder in the nuclear source compared with surrounding regions. The emission-line spectrum can be explained by a young (<5 Myr) nuclear star cluster with stellar mass ∼3 × 10 4 M ⊙ , but the unresolved continuum source is more typical for a deeply embedded AGN powered by a black hole of minimum mass ∼1450 M ⊙ . These observations reveal that either a metal-poor stellar population can heat the dust to extremely high temperatures, a result that would have significant impact on the reliability of MIR color selection in AGN surveys and our understanding of the properties of the interstellar medium and young stars in metal-poor galaxies, or an accreting intermediate-mass black hole is deeply embedded and hidden even at near-infrared wavelengths.}, archive = {J_ApJ}, author = {Sara Doan and Shobita Satyapal and William Matzko and Nicholas P. Abel and Torsten Böker and Thomas Bohn and Gabriela Canalizo and Jenna M. Cann and Jacqueline Fischer and Stephanie LaMassa and Suzanne C. Madden and Jeffrey D. McKaig and D. Schaerer and Nathan J. Secrest and Anil Seth and Laura Blecha and Mallory Molina and Barry Rothberg}, doi = {10.3847/1538-4357/adcd59}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {99}, shortjournal = {The Astrophys. J.}, title = {Local analogs of primordial galaxies: In search of intermediate-mass black holes with JWST NIRSpec}, volume = {987}, year = {2025}, }
• (2025). Quantifying suppression of solar surface magnetic flux advection with increasing field strength. ApJ, 987(1), 98. (www)

  @article{ , abstract = {One of the main theories for heating of the solar corona is based on the idea that solar convection shuffles and tangles magnetic field lines to make many small-scale current sheets that, via reconnection, heat coronal loops. S. K. Tiwari et al. present evidence that, besides depending on loop length and other factors, the brightness of a coronal loop depends on the field strength in the loop’s feet and the freedom of convection in the feet. While it is known that strong solar magnetic fields suppress convection, the decrease in the speed of horizontal advection of magnetic flux with increasing field strength has not been quantified before. We quantify that trend by analyzing 24 hr of Helioseismic Magnetic Imager-SHARP vector magnetograms of each of six sunspot-active regions and their surroundings. Using Fourier local correlation tracking, we estimate the horizontal advection speed of the magnetic flux at each pixel in which the vertical component of the magnetic field strength ( Bz ) is well above (≥150 G) noise level. We find that the average horizontal advection speed of magnetic flux steadily decreases as Bz increases, from 110  ±  3 m s −1 for 150 G (in network and plage) to 10  ±  4 m s −1 for 2500 G (in sunspot umbra). The trend is well fit by a fourth-degree polynomial. These results quantitatively confirm the expectation that magnetic flux advection is suppressed by increasing magnetic field strength. The presented quantitative relation should be useful for future MHD simulations of coronal heating.}, archive = {J_ApJ}, author = {V. Aparna and Sanjiv K. Tiwari and Ronald L. Moore and Navdeep K. Panesar and Brian Welsch and Bart De Pontieu and Aimee Norton}, doi = {10.3847/1538-4357/add5eb}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {98}, shortjournal = {The Astrophys. J.}, title = {Quantifying suppression of solar surface magnetic flux advection with increasing field strength}, volume = {987}, year = {2025}, }
• (2025). Asteroseismic structure inversions of main-sequence solar-like oscillators with convective cores. ApJ, 987(1), 97. (www)

  @article{ , abstract = {Asteroseismic inferences of main-sequence solar-like oscillators often rely on best-fit models. However, these models cannot fully reproduce the observed mode frequencies, suggesting that the internal structure of the model does not fully match that of the star. Asteroseismic structure inversions provide a way to test the interior of our stellar models. Recently, structure inversion techniques were used to study 12 stars with radiative cores. In this work, we extend that analysis to 43 main-sequence stars with convective cores observed by Kepler to look for differences in the sound speed profiles in the inner 30% of the star by radius. For around half of our stars, the structure inversions show that our models reproduce the internal structure of the star, where the inversions are sensitive, within the observational uncertainties. For the stars where our inversions reveal significant differences, we find cases where our model sound speed is too high and cases where our model sound speed is too low. We use the star with the most significant differences to explore several changes to the physics of our model in an attempt to resolve the inferred differences. These changes include using a different overshoot prescription and including the effects of diffusion, gravitational settling, and radiative levitation. We find that the resulting changes to the model structure are too small to resolve the differences shown in our inversions.}, archive = {J_ApJ}, author = {Lynn Buchele and Earl P. Bellinger and Saskia Hekker and Sarbani Basu}, doi = {10.3847/1538-4357/add697}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {97}, shortjournal = {The Astrophys. J.}, title = {Asteroseismic structure inversions of main-sequence solar-like oscillators with convective cores}, volume = {987}, year = {2025}, }
• (2025). Toward characterizing dark matter subhalo perturbations in stellar streams with graph neural networks. ApJ, 987(1), 96. (www)

  @article{ , abstract = {The phase space of stellar streams is proposed to detect dark substructure in the Milky Way through the perturbations created by passing subhalos—and thus is a powerful test of the cold dark matter paradigm and its alternatives. Using graph convolutional neural network (GCNN) data compression and simulation-based inference (SBI) on a simulated GD-1-like stream, we improve the constraint on the mass of a [10 8 , 10 7 , 10 6 ] M ⊙ perturbing subhalo by factors of [11, 7, 3] with respect to the current state-of-the-art density power spectrum analysis. We find that the GCNN produces posteriors that are more accurate (better calibrated) than the power spectrum. We simulate the positions and velocities of stars in a GD-1-like stream and perturb the stream with subhalos of varying mass and velocity. Leveraging the feature encoding of the GCNN to compress the input phase space data, we then use SBI to estimate the joint posterior of the subhalo mass and velocity. We investigate how our results scale with the size of the GCNN, the coordinate system of the input, and the effect of incomplete observations. Our results suggest that a survey with 10× fewer stars (300 stars) with complete 6D phase space data performs about as well as a deeper survey (3000 stars) with only 3D data (photometry, spectroscopy). The stronger constraining power and more accurate posterior estimation motivate further development of GCNNs in combining future photometric, spectroscopic, and astrometric stream observations.}, archive = {J_ApJ}, author = {Peter Xiangyuan Ma and Keir K. Rogers and Ting S. Li and Renée Hložek and Jeremy J. Webb and Ruth Huang and Julian Meunier}, doi = {10.3847/1538-4357/add698}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {96}, shortjournal = {The Astrophys. J.}, title = {Toward characterizing dark matter subhalo perturbations in stellar streams with graph neural networks}, volume = {987}, year = {2025}, }
• (2025). Ultraviolet properties of multiphase gas toward the inner galaxy. ApJ, 987(1), 95. (www)

  @article{ , abstract = {We present a systematic study of the multiphase interstellar gas in the inner Galaxy using Hubble Space Telescope/STIS absorption spectroscopy of 16 massive stars located at spectroscopic distances between 1.3 and 10 kpc in the region −30° ≲ l ≲ +30° and −15° ≲ b ≲ +15°. These sight lines probe gas above and below the Sagittarius Carina, Scutum Crux-Centaurus, Norma, and Near 3-kpc spiral arms in a range of z -height from 0 to 1.5 kpc. Along the 16 sight lines, we measure velocity centroids for 800 UV absorption-line components across multiple gas phases (molecular CO, neutral, low ion, and high ion). We find that 619/800 components have velocities that are consistent with a simple model of corotation with the disk, indicating that multiphase gas with disk-like kinematics extends at least 1 kpc into the halo. We present a database of absorption-line parameters that can be used for kinematic modeling of gas flows into and out of the Galactic disk.}, archive = {J_ApJ}, author = {Frances H. Cashman and Andrew J. Fox and Debopam Som and Bart P. Wakker and Robert A. Benjamin and Dhanesh Krishnarao and David M. French and Rongmon Bordoloi and Felix J. Lockman}, doi = {10.3847/1538-4357/add69b}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {95}, shortjournal = {The Astrophys. J.}, title = {Ultraviolet properties of multiphase gas toward the inner galaxy}, volume = {987}, year = {2025}, }
• (2025). The magnified waltz: Simulating light curves of binary stars passing through microcaustics in strong lensing galaxy clusters. ApJ, 987(1), 94. (www)

  @article{ , abstract = {Individual stars located near the caustics of galaxy clusters can undergo extreme magnification when crossing microcaustics, rendering them observable even at cosmological distances. Though most massive stars are likely to reside in binary systems rather than as single star, the influence of a binary star system on magnification events is severely underexplored. In this work, we simulate the light curves produced by detached binary stars crossing microcaustics, aiming to characterize their unique observational signatures. Using high-resolution magnification maps generated by the GPU-PMO-CAUSTIC algorithm and PARSEC stellar models with red-shifted magnitude, we examined the impact of binary star parameters and crossing geometries on microlensing magnification patterns. Our simulations reveal that binary stars produce diverse light-curve features, including overlapping peaks, plateau-like structures, and time-variable color–magnitude differences. These features, particularly the distinct temporal variations in spectral energy distributions, offer diagnostic tools for distinguishing binary systems from single stars. We further demonstrate the potential of multiband photometry using the Chinese Space Station Telescope’s Multi-Channel Imager to capture these variations. Our findings provide theoretical support to identify binary systems in future caustic-crossing events, enabling more accurate characterization of high-redshift stellar populations.}, archive = {J_ApJ}, author = {Wenwen Zheng and Xiaoting Fu and Yang Chen and Xuefei Chen and Yanjun Guo and Xuechun Chen and Huanyuan Shan and Guoliang Li}, doi = {10.3847/1538-4357/add72a}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {94}, shortjournal = {The Astrophys. J.}, title = {The magnified waltz: Simulating light curves of binary stars passing through microcaustics in strong lensing galaxy clusters}, volume = {987}, year = {2025}, }
• (2025). Statistics of the interplanetary magnetic field from 0.1 to 30 au. II. dynamical variability. ApJ, 987(1), 93. (www)

  @article{ , abstract = {The interplanetary magnetic field (IMF) governs the coupling between the solar wind and planetary magnetospheres through a series of complex interactions. However, it is challenging to simultaneously measure both the upstream IMF conditions and magnetospheric activity in situ. A common alternative approach is to utilize recent upstream measurements obtained before the spacecraft crosses the bow shock. To assess the validity of this method, we examine the temporal variability of the IMF using spacecraft magnetic field data from multiple space missions. Our analysis reveals that the autocorrelation function employed to measure IMF temporal variability is significantly influenced by the heliocentric distance and the solar cycle. Notably, the temporal variability of each magnetic field component varies, with the component aligned with the Parker spiral direction exhibiting weaker temporal variability than those perpendicular to it. Furthermore, the autocorrelation coefficients decay slower in the outer heliosphere, possibly due to the expansion, deformation, or merging of solar wind flux tubes. Nevertheless, considering planetary bow shocks and spacecraft travel time from the solar wind to the inner planetary magnetosphere (e.g., ∼2 hrs for Mars and ∼30 days for Jupiter), it is more feasible to estimate the upstream IMF conditions for the inner planetary magnetosphere than for the outer ones. Our study unravels the long-term evolution of the solar wind magnetic field and the consequence of the flux tube interaction. These results can also benefit the investigation of the solar wind–planetary magnetosphere coupling process by providing a more robust analysis of the upstream condition.}, archive = {J_ApJ}, author = {Jiutong Zhao and Shan Wang and Weijie Sun and Xingyu Zhu and Chuanpeng Hou and Qiugang Zong and Jiansen He and Xuzhi Zhou and Chao Yue and Liu Yang and Daniel Heyner}, doi = {10.3847/1538-4357/add72f}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {93}, shortjournal = {The Astrophys. J.}, title = {Statistics of the interplanetary magnetic field from 0.1 to 30 au. II. dynamical variability}, volume = {987}, year = {2025}, }
• (2025). Physical conditions of the ionized superwind in NGC 253 with VLT/MUSE. ApJ, 987(1), 92. (www)

  @article{ , abstract = {We present an analysis of the H α -emitting ionized gas in the warm phase of the NGC 253 outflow using integral field spectroscopy from the Multi Unit Spectroscopic Explorer. In each spaxel, we decompose H α , [N ii ], and [S ii ] emission lines into a system of up to three Gaussian components, accounting for the velocity contributions due to the disk and both intercepted walls of an outflow cone. In the approaching southern lobe of the outflow, we find maximum deprojected outflow velocities down to ∼−500 km s −1 . Velocity gradients of this outflowing gas range from ∼−350 to −550 km s −1 kpc −1 with increasing distance from the nucleus. Additionally, [N ii ]/H α and [S ii ]/H α integrated line ratios are suggestive of shocks as the dominant ionization source throughout the wind. Electron densities, inferred from the [S ii ] doublet, peak at 2100 cm −3 near the nucleus and reach ≲50 cm −3 in the wind. Finally, at an uncertainty of 0.3 dex on the inferred mass of 4 × 10 5 M ⊙ , the mass-outflow rate of the H α -emitting gas in the southern outflow lobe is ∼0.4 M ⊙ yr −1 . This yields a mass-loading factor of η ∼ 0.1 and a ∼2% starburst energy efficiency.}, archive = {J_ApJ}, author = {Serena A. Cronin and Alberto D. Bolatto and Enrico Congiu and Keaton Donaghue and Kathryn Kreckel and Adam K. Leroy and Rebecca C. Levy and Sylvain Veilleux and Fabian Walter and Lenin Nolasco}, doi = {10.3847/1538-4357/add738}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {92}, shortjournal = {The Astrophys. J.}, title = {Physical conditions of the ionized superwind in NGC 253 with VLT/MUSE}, volume = {987}, year = {2025}, }
• (2025). Relationships between polycyclic aromatic hydrocarbons, small dust grains, h2, and h i in local group dwarf galaxies NGC 6822 and WLM using JWST, ALMA, and the VLA. ApJ, 987(1), 91. (www)

  @article{ , abstract = {We present 0.6–3.2 pc resolution mid-infrared (MIR) JWST images at 7.7 μ m (F770W) and 21 μ m (F2100W) covering the main star-forming regions of two of the closest star-forming low-metallicity dwarf galaxies, NGC 6822 and Wolf–Lundmark–Melotte (WLM). The images of NGC 6822 reveal filaments, edge-brightened bubbles, diffuse emission, and a plethora of point sources. By contrast, most of the MIR emission in WLM is pointlike, with a small amount of extended emission. Compared to solar-metallicity galaxies, the ratio of 7.7 μ m intensity ( {I}_{\nu }^{{\rm{F770W}}} ), tracing polycyclic aromatic hydrocarbons (PAHs), to 21 μ m intensity ( {I}_{\nu }^{{\rm{F2100W}}} ), tracing small, warm dust grain emission, is suppressed in these low-metallicity dwarfs. Using Atacama Large Millimeter/submillimeter Array CO(2–1) observations, we find that detected CO intensity versus {I}_{\nu }^{{\rm{F770W}}} at ≈2 pc resolution in dwarfs follows a similar relationship to that at solar metallicity and lower resolution, while the CO versus {I}_{\nu }^{{\rm{F2100W}}} relationship in dwarfs lies significantly below that derived from solar-metallicity galaxies at lower resolution, suggesting more pronounced destruction of CO molecules at low metallicity. Finally, adding in Local Group L-Band Survey 21 cm H i observations from the Very Large Array, we find that {I}_{\nu }^{{\rm{F2100W}}} and {I}_{\nu }^{{\rm{F770W}}} versus total gas ratios are suppressed in NGC 6822 and WLM compared to solar-metallicity galaxies. In agreement with dust models, the level of suppression appears to be at least partly accounted for by the reduced galaxy-averaged dust-to-gas and PAH-to-dust mass ratios in the dwarfs. Remaining differences are likely due to spatial variations in dust model parameters, which should be an exciting direction for future work in local dwarf galaxies.}, archive = {J_ApJ}, author = {Ryan Chown and Adam K. Leroy and Alberto D. Bolatto and Jérémy Chastenet and Simon C. O. Glover and Rémy Indebetouw and Eric W. Koch and Jennifer Donovan Meyer and Nickolas M. Pingel and Erik Rosolowsky and Karin Sandstrom and Jessica Sutter and Elizabeth Tarantino and Frank Bigiel and Médéric Boquien and I-Da Chiang and Daniel A. Dale and Julianne J. Dalcanton and Oleg V. Egorov and Cosima Eibensteiner and Kathryn Grasha and Hamid Hassani and Hao He and Jaeyeon Kim and Sharon Meidt and Debosmita Pathak and Sumit K. Sarbadhicary and Snezana Stanimirovic and Vicente Villanueva and Thomas G. Williams}, doi = {10.3847/1538-4357/add73a}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {91}, shortjournal = {The Astrophys. J.}, title = {Relationships between polycyclic aromatic hydrocarbons, small dust grains, h2, and h i in local group dwarf galaxies NGC 6822 and WLM using JWST, ALMA, and the VLA}, volume = {987}, year = {2025}, }
• (2025). Low-redshift analogs of cosmic noon galaxies as laboratories for clumpy star formation. ApJ, 987(1), 90. (www)

  @article{ , abstract = {It has been established that a significant fraction of star formation at high redshift occurs in clumpy galaxies. The properties of clumps and their formation mechanisms, however, remain highly debated. In this work we analyze a sample of 18 supercompact ultraviolet luminous galaxies observed with the OSIRIS spectrograph at the Keck Telescope, targeting their Pa α emission. These galaxies, although at z ∼ 0.1–0.2, share many similar properties with star-forming galaxies at cosmic noon. We find a total of 84 star-forming clumps with typical sizes of a few hundred parsecs. The star-forming clumps exhibit low values of velocity shear (∼12 km s −1 ) and high velocity dispersion (∼70 km s −1 ). The dynamical masses of the clumps are typically higher than the gas masses inferred from the measured star formation rate of each clump. We also artificially redshift our data to emulate observations at z = 2.2 and allow for a direct comparison with other galaxies at higher redshift. Our results indicate that, due to the effects of clump clustering and low-resolution observations, high- z clumps appear larger at greater cosmological distances. This underscores the importance of using low-redshift observations to anchor studies at earlier epochs. Finally, our results support the idea of growing clump sizes in star-forming galaxies as a function of redshift, although not to the scales of kiloparsecs as found by other works without the benefits of adaptive optics or gravitational lensing.}, archive = {J_ApJ}, author = {Jorge M. Santos-Junior and Thiago S. Gonçalves and Luidhy Santana-Silva and Arianna Cortesi and Karin Menendez-Delmestre and Amanda E. Araujo-Carvalho}, doi = {10.3847/1538-4357/add926}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {90}, shortjournal = {The Astrophys. J.}, title = {Low-redshift analogs of cosmic noon galaxies as laboratories for clumpy star formation}, volume = {987}, year = {2025}, }
• (2025). Photometric and spectroscopic studies of two early-type eclipsing binaries. ApJ, 987(1), 89. (www)

  @article{ , abstract = {Using high-precision photometric data from the Transiting Exoplanet Survey Satellite, medium-resolution spectroscopic data from the Large Sky Area Multi-Object Fiber Spectroscopy Telescope, and long-term eclipse timings, we provide orbital parameters for two early-type detached eclipsing binary systems: TYC 3740-2072-1 and TYC 2888-780-1, and analyze the orbital period variations and evolutionary status of these two targets. TYC 3740-2072-1, with a spectral type of B1V, consists of a 6.914 M ⊙ subgiant and a 6.233 M ⊙ main-sequence component. It is expected to evolve into a semidetached binary, potentially serving as a progenitor of a Type Ia supernova. TYC 2888-780-1 has a spectral type of A3 and consists of two main-sequence components with masses of 1.682 and 1.673 M ⊙ , respectively. It is undergoing stable evolution. Through eclipse timing analysis, we find that both targets exhibit apsidal motion effects, with observed apsidal motion rates of {\dot{\omega }}_{\mathrm{obs}}=0.0412\,\,\rm{deg}\,\,{\,\rm{cycle}\,}^{-1} and {\dot{\omega }}_{\mathrm{obs}}=0.0205\,\,\rm{deg}\,\,{\,\rm{cycle}\,}^{-1} , respectively. Additionally, TYC 2888-780-1 exhibits orbital period variations, which we attribute to the light travel time effect caused by a third body; the minimum mass of this third body is estimated to be 0.598 M ⊙ .}, archive = {J_ApJ}, author = {Pengfei Ye and Kai Li and Fei Liu and Xiang Gao and Jing-Yi Wang}, doi = {10.3847/1538-4357/addd19}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {89}, shortjournal = {The Astrophys. J.}, title = {Photometric and spectroscopic studies of two early-type eclipsing binaries}, volume = {987}, year = {2025}, }
• (2025). Low-metallicity nova explosions: A site for weak rp-process nucleosynthesis. ApJ, 987(1), 88. (www)

  @article{ , abstract = {Classical novae are common cataclysmic events involving a binary system of a white dwarf and a main-sequence or red giant companion star. In metal-poor environments, these explosions produce ejecta differently from their solar counterparts due to the accretion of subsolar-metallicity material onto the white dwarf. In particular, it has been suggested that the nucleosynthesis flow in such low-metallicity nova explosions extends up to the Cu–Zn region, much beyond the expected endpoint, around Ca, predicted for solar-metallicity classical novae. This behavior resembles a weak rp -process, and such nuclear activity has never been observed in accreting white dwarf binaries with typical accretion flows. In this work, we study the characteristics of the weak rp -process for four nova models with metallicities Z = 2 × 10 −9 , 10 −7 , 2 × 10 −6 , and 2 × 10 −5 , and explore the impact of the nuclear physics uncertainties via a Monte Carlo sensitivity study. We identify nuclear reactions whose uncertainties affect the production of intermediate-mass nuclei under these conditions. These reactions and relevant nuclear quantities are targets for measurements at stable or radioactive beam facilities to reduce their rate uncertainties.}, archive = {J_ApJ}, author = {Athanasios Psaltis and Jordi José and Richard Longland and Christian Iliadis}, doi = {10.3847/1538-4357/addfd5}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {88}, shortjournal = {The Astrophys. J.}, title = {Low-metallicity nova explosions: A site for weak rp-process nucleosynthesis}, volume = {987}, year = {2025}, }
• (2025). The TRGB−SBF project. III. refining the HST surface brightness fluctuation distance scale calibration with JWST. ApJ, 987(1), 87. (www)

  @article{ , abstract = {The TRGB−SBF Project team is developing an independent distance ladder using a geometrical calibration of the tip of the red giant branch (TRGB) method in elliptical galaxies that can, in turn, be used to set the surface brightness fluctuation (SBF) distance scale independent of Cepheid variables and Type Ia supernovae. The purpose of this project is to measure the local expansion rate of the Universe independently of the methods that are most at odds with the theoretically predicted value of the Hubble–Lemaître constant H 0 , and therefore isolate the influence of potential systematic observational errors. In this paper, we use JWST TRGB distances calibrated using the megamaser galaxy NGC 4258 to determine a new Cepheid-independent SBF zero-point with the Hubble Space Telescope. This new calibration, along with improved optical color measurements from Pan-STARRS and DECam, gives an updated value of H 0 = 73.8 ± 0.7 (statistical) ±2.3 (systematic) km s −1 Mpc −1 that is virtually identical to the SBF Hubble–Lemaître constant measured by J. P. Blakeslee et al.}, archive = {J_ApJ}, author = {Joseph B. Jensen and John P. Blakeslee and Michele Cantiello and Mikaela Cowles and Gagandeep S. Anand and R. Brent Tully and Ehsan Kourkchi and Gabriella Raimondo}, doi = {10.3847/1538-4357/addfd6}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {87}, shortjournal = {The Astrophys. J.}, title = {The TRGB−SBF project. III. refining the HST surface brightness fluctuation distance scale calibration with JWST}, volume = {987}, year = {2025}, }
• (2025). ASURA-FDPS-ML: Star-by-star galaxy simulations accelerated by surrogate modeling for supernova feedback. ApJ, 987(1), 86. (www)

  @article{ , abstract = {We introduce new high-resolution galaxy simulations accelerated by a surrogate model that reduces the computation cost by approximately 75%. Massive stars with a zero-age main-sequence mass of more than about 10 M ⊙ explode as core-collapse supernovae (CCSNe), which play a critical role in galaxy formation. The energy released by CCSNe is essential for regulating star formation and driving feedback processes in the interstellar medium (ISM). However, the short integration time steps required for SN feedback have presented significant bottlenecks in astrophysical simulations across various scales. Overcoming this challenge is crucial for enabling star-by-star galaxy simulations, which aim to capture the dynamics of individual stars and the inhomogeneous shell’s expansion within the turbulent ISM. To address this, our new framework combines direct numerical simulations and surrogate modeling, including machine learning and Gibbs sampling. The star formation history and the time evolution of outflow rates in the galaxy match those obtained from resolved direct numerical simulations. Our new approach achieves high-resolution fidelity while reducing computational costs, effectively bridging the physical scale gap and enabling multiscale simulations.}, archive = {J_ApJ}, author = {Keiya Hirashima and Kana Moriwaki and Michiko S. Fujii and Yutaka Hirai and Takayuki R. Saitoh and Junichiro Makino and Ulrich P. Steinwandel and Shirley Ho}, doi = {10.3847/1538-4357/add689}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {86}, shortjournal = {The Astrophys. J.}, title = {ASURA-FDPS-ML: Star-by-star galaxy simulations accelerated by surrogate modeling for supernova feedback}, volume = {987}, year = {2025}, }
• (2025). Heliospheric current sheet crossings observed by voyager 2 across 1–33.6 au. ApJ, 987(1), 59. (www)

  @article{ , abstract = {In this study, we identified 188 heliospheric current sheet (HCS) crossing events observed by Voyager 2 between 1977 and 1990, spanning heliocentric distances from 1 to 33.6 au. The identified HCS crossings revealed well-defined trends including a >30% decrease in magnetic field intensity and >20% increases in proton density and temperature. The Harris sheet model fitting to all 188 HCS crossing events indicates that the estimated HCS thickness spans over 2 orders of magnitude, ranging from 7\times {10}^{3} to 2.5\times {10}^{6} km, with a median value of 3.3\times {10}^{5} km. For 84.6% of the events, the HCS planes lie within -30^\circ to 30^\circ in latitude from the equatorial plane, whereas the others indicate highly tilted HCS planes. Similarly, for 85.6% of the events, the HCS planes align with the Parker spiral field from the Parker field direction (within 30°), whereas the others exhibit significant longitudinal tilt. Additionally, a substantial fraction of HCS crossings indicate a significant normal magnetic field component (e.g., {B}_{\mathrm{normal}}/\left|B\right|\,\gt 0.3 for 38.8% of the total events), implying rotational discontinuities. Comparing our results with previous studies on HCS thickness from near the Sun to the heliosheath, we find a general increase in thickness with distance. Notably, at 1–33.6 au, HCS thickness remains significantly larger than the ion inertial length, implying conditions generally unfavorable for magnetic reconnection. This contrasts with recent reports of frequent reconnection at HCSs closer to the Sun. Our findings provide a comprehensive insight into the HCS structures across a wide range of heliospheric distances.}, archive = {J_ApJ}, author = {Dooyoung Choi and Dae-Young Lee}, doi = {10.3847/1538-4357/adde44}, journal = {The Astrophysical Journal}, month = {7}, number = {1}, pages = {59}, shortjournal = {The Astrophys. J.}, title = {Heliospheric current sheet crossings observed by voyager 2 across 1–33.6 au}, volume = {987}, year = {2025}, }
• (2025). Characterizing exoplanets for assessing their potential habitability. ApJ, 987(1), 85. (www)

  @article{ , abstract = {The Statistical-likelihood Exoplanetary Habitability Index (SEPHI) serves as a valuable tool for prioritizing targets for further study and identifying potentially habitable environments. In this paper, we present SEPHI 2.0, which incorporates several key improvements: (1) updated methods for estimating exoplanet internal structures and magnetic fields; (2) the inclusion of orbital eccentricity in assessing the potential for liquid water on an exoplanet’s surface; and (3) a new exoplanet mass–radius relationship. SEPHI 2.0 retains its probabilistic framework and combines the different subindexes by selecting the most restrictive one. In SEPHI 2.0, atmospheric retention is consolidated into a single index that incorporates both thermal (Jeans escape) and nonthermal (stellar wind and magnetic effect) processes. Recent advancements in estimating exoplanet internal structures and magnetic fields have been integrated. Additionally, a new empirical exoplanet mass–radius relationship is introduced. All this is incorporated into the SADE code, which uses key data on exoplanets and their host stars to assess habitability and prioritize targets for further study, providing a comprehensive output of an exoplanetary system’s physical characteristics. SADE is available as a free online tool. Notably, this is the first approach to including estimated exoplanet magnetic fields in a habitability index. The SADE software facilitates the identification of potentially habitable exoplanets. Among the 5500+ confirmed exoplanets, only a few—such as Kepler-62f and GJ 514b—achieve SEPHI 2.0 scores close to 1. It is also noticeable that, according to our studies, TRAPPIST-1 f and g are ranked higher than TRAPPIST-1 e in terms of habitability potential.}, archive = {J_ApJ}, author = {J. M. Rodríguez-Mozos and A. Moya}, doi = {10.3847/1538-4357/adddbf}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {85}, shortjournal = {The Astrophys. J.}, title = {Characterizing exoplanets for assessing their potential habitability}, volume = {987}, year = {2025}, }
• (2025). Small-scale inhomogeneity effects on coherent solar radio emission. ApJ, 987(1), 84. (www)

  @article{ , abstract = {The coherent radio emission mechanism of solar radio bursts (SRBs) is one of the most complicated and controversial topics in solar physics. To clarify the mechanism(s) of different types of SRBs, (radio-) wave excitation by energetic electrons in homogeneous plasmas has been widely studied via particle-in-cell (PIC) code numerical simulations. The solar corona is, however, inhomogeneous over almost all spatial scales. Due to the kinetic nature of SRBs, small-scale inhomogeneities in the plasma could influence the excitation and emission properties of SRBs. In this paper, we thus investigate the effects of small-scale inhomogeneity (in the magnetic field as well as plasma density or temperature) of plasmas in the solar corona on radio-wave emission by ring-beam distributed energetic electrons utilizing 2.5-dimensional PIC simulations. The typical length scale of the small-scale inhomogeneity we consider in this study is on the order of the proton gyroradius. Both beam and electron-cyclotron maser instabilities can be triggered with the presence of energetic ring-beam electrons. The resultant spectrum of the excited electromagnetic waves presents a zebra-stripe pattern in the frequency space. The inhomogeneous density or temperature in plasmas influences the frequency bandwidth and location of these excited waves. Our results can hence help to diagnose the plasma properties at the emission sites of SRBs. Applications of our results to SRBs with a zebra-stripe pattern are discussed.}, archive = {J_ApJ}, author = {Xiaowei Zhou and Patricio A. Muñoz and Jan Benáček and Lijie Zhang and Dejin Wu and Ling Chen and Zongjun Ning and Jörg Büchner}, doi = {10.3847/1538-4357/add32a}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {84}, shortjournal = {The Astrophys. J.}, title = {Small-scale inhomogeneity effects on coherent solar radio emission}, volume = {987}, year = {2025}, }
• (2025). Physics-based forecasting of tomorrow’s solar wind at 1 au. ApJ, 987(1), 83. (www)

  @article{ , abstract = {Inspired by the concept of relativity of simultaneity used in the theory of special relativity, a new approach is proposed to simulate future solar wind conditions at any point in the inner solar system. An important distinctive feature of the proposed approach is that the simulation in the solar corona is driven by hourly updated solar magnetograms and is continuously simulated in nearly real time. The model for the inner heliosphere is based on time transformation to a boosted spacetime coordinate system, in which the current state of the solar wind at the solar corona–inner heliosphere boundary and future states of the solar wind are simultaneous. The predictive capability for tomorrow’s parameters of the ambient solar wind at 1 au is achieved by simulating them simultaneously with the current observations of the solar magnetic field, the time offset being enabled by the use of a boosted frame. We derive the modified governing equations for both hydrodynamics and magnetohydrodynamics and present a new numerical algorithm that solves the modified governing equations. The proposed method enables an efficient numerical implementation and thus a significantly longer forecast time than traditional solution methods. In the numerical test for transient propagation, the boosted solution for the coronal mass ejection–driven shock arrival at 1 au is 16 hr ahead of the solution at the solar corona–inner heliosphere boundary.}, archive = {J_ApJ}, author = {Igor V. Sokolov and Tamas I. Gombosi}, doi = {10.3847/1538-4357/add52f}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {83}, shortjournal = {The Astrophys. J.}, title = {Physics-based forecasting of tomorrow’s solar wind at 1 au}, volume = {987}, year = {2025}, }
• (2025). The pitfalls of using lyα damping wings in high-z galaxy spectra to measure the intergalactic neutral hydrogen fraction. ApJ, 987(1), 82. (www)

  @article{ , abstract = {The Ly α damping wing is seen in absorption against the spectra of high-redshift galaxies. Modeling of this wing is a way to measure the volume neutral hydrogen fraction of the Universe, as well as to measure the strength of H i absorption in the form of a damped Ly α absorber (DLA). We use very-high-quality ultraviolet spectra of low- z galaxies to create mock high-redshift, low-resolution spectra complete with a damping wing resulting from the intergalactic medium (IGM) and H i absorption from local, dense gas to mimic current James Webb Space Telescope observations of the early Universe. The simulated spectra are used to test the ability to recover the “true” values of the column density of the DLA ( N DLA ) and the volume neutral hydrogen fraction ( x H I ) of the IGM through modified stellar continuum fitting. We find that the ability to recover the true values of N DLA and x H I simultaneously is compromised by degeneracies between these two parameters, and the spectral shape itself at low resolution ( R ∼ 100). The root mean squared error between the recovered and true column density of the DLA is on the order of 1 dex. This error somewhat decreases with improved resolution ( R ∼ 1000), but systematically underestimates N DLA when Ly α emission is present in the mock spectra. The recovered values of x H I are poorly constrained and do not improve substantially with the higher resolution. We recommend accounting for these sources of uncertainty and biases when using galaxies’ Ly α damping wings to measure the intergalactic neutral hydrogen fraction.}, archive = {J_ApJ}, author = {Mason Huberty and Claudia Scarlata and Matthew J. Hayes and Simon Gazagnes}, doi = {10.3847/1538-4357/add5e7}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {82}, shortjournal = {The Astrophys. J.}, title = {The pitfalls of using lyα damping wings in high-z galaxy spectra to measure the intergalactic neutral hydrogen fraction}, volume = {987}, year = {2025}, }
• (2025). Iron snails: Nonequilibrium dynamics and spiral abundance patterns. ApJ, 987(1), 81. (www)

  @article{ , abstract = {Galaxies are not in a dynamical steady state: they continually undergo perturbations, e.g., from infalling dwarf galaxies and dark matter substructure. After a dynamical perturbation, stars phase mix toward a new steady state; in so doing, they generally form spiral structures, such as spiral density waves in galaxy disks and the Gaia Snail observed in the vertical phase-space density in the solar neighborhood. Structures in phase-space density can be hard to measure accurately, because spatially varying selection effects imprint their own patterns on the density. However, stellar labels such as metallicity, or other element abundances, or stellar masses and ages, can be measured even in the face of complex or unknown spatial selection functions. We show that if the equilibrium galaxy has phase-space gradients in these labels, any perturbation that could raise a spiral wave in the phase-space density will raise a spiral wave in the distribution of labels as well. We work out the relationship between the spiral patterns in the density and in the labels. As an example, we analyze the Gaia Snail, and show that its amplitude and dynamical age as derived from elemental abundances (mainly [Mg/Fe]) follow similar patterns to those derived from the phase-space density. Our best model dates the Snail’s perturbation to about 400 Myr ago, although we find significant variations with angular momentum in the best-fit age. Conceptually, the ideas presented here are related to orbital torus imaging, chemical tagging, and other methods that use stellar labels to trace dynamics.}, archive = {J_ApJ}, author = {Neige Frankel and David W. Hogg and Scott Tremaine and Adrian Price-Whelan and Jeff Shen}, doi = {10.3847/1538-4357/add5ea}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {81}, shortjournal = {The Astrophys. J.}, title = {Iron snails: Nonequilibrium dynamics and spiral abundance patterns}, volume = {987}, year = {2025}, }
• (2025). In-depth analysis of the 2022 march 28 3He-rich solar energetic particle event. ApJ, 987(1), 80. (www)

  @article{ , abstract = {On 2022 March 28, a solar eruption from active region AR 12975 produced a solar energetic particle (SEP) event observed by BepiColombo (BC; 0.57 au), STEREO-A (STA; 0.97 au), GOES (1.0 au), ACE (L1), and Wind (L1). The event was associated with an M4.0 soft X-ray flare peaking at 11:29 UTC, a Type III radio burst (0.1–16 MHz) at 11:24 UTC, a metric Type II radio burst (25–250 MHz) at 11:23 UTC, and a coronal mass ejection with a speed of 700 km s −1 . BC and STA, magnetically aligned along the same Parker spiral and well connected to the flare site (footpoint separations of 19 \mathop{.}\limits^{\unicode{x000b0}} 8 and 16 \mathop{.}\limits^{\unicode{x000b0}} 5, respectively), detected a gradual SEP event with remarkable impulsive characteristics, including a high 3 He/ 4 He ratio (0.7 at 1 MeV), elevated Fe/O ratio (∼0.5 increasing with energy), a 3 He spectrum harder than that of other ions, and particle dropouts at BC linked to intermittent magnetic connections. Near-Earth spacecraft (44 \mathop{.}\limits^{\unicode{x000b0}} 8 from the flare site) observed abundance ratios closer to coronal values, and more uniform proton/heavy-ion spectra. Our findings suggest both the contribution of particles accelerated by a quasi-parallel shock and a direct contribution from flare suprathermals, accelerated during postflare ongoing reconnection, at well connected spacecraft.}, archive = {J_ApJ}, author = {Mirko Stumpo and Monica Laurenza and Simone Benella and Anna Milillo and Christina Plainaki and Matthew J. West and Pietro Zucca and Stas Barabash and Daniel Heyner and Ali Varsani and Go Murakami and Shyama Narendranath and Alessandro Aronica and H. U. Auster and Lorenzo Biasiotti and Alessandro Brin and Luca Colasanti and D. Constantinescu and Elisabetta De Angelis and Pier Paolo Di Bartolomeo and D. Fischer and Stavro Ivanovski and Harald Jeszenszky and Adrian Kazakov and Gunter Laky and Valeria Mangano and Stefano Massetti and Martina Moroni and Alessandro Mura and Livio Narici and Hans Nilsson and Raffaella Noschese and Stefano Orsini and Grace Richards and I. Richter and Rosanna Rispoli and Beatriz Sanchez-Cano and Roberto Sordini and Srikar P. Tadepalli and Nello Vertolli and Martin Wieser and Hayley Williamson}, doi = {10.3847/1538-4357/add5f1}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {80}, shortjournal = {The Astrophys. J.}, title = {In-depth analysis of the 2022 march 28 3He-rich solar energetic particle event}, volume = {987}, year = {2025}, }
• (2025). Prospect of gamma-ray burst neutrino detection with enhanced neutrino detectors. ApJ, 987(1), 79. (www)

  @article{ , abstract = {Gamma-ray bursts (GRBs) have long been proposed as a potential source of high-energy neutrinos. Although no confirmed association between GRBs and neutrinos has been established, meaningful constraints have been placed on GRB prompt emission models. The nondetection of neutrinos, reported by the IceCube Collaboration, from both single and stacked GRB events suggests that the radiation zone is likely located at a considerable distance from the central engine, where the photon number density is relatively low. Here, we estimate future GRB neutrino detection probabilities using detectors with a higher simulated sensitivity than IceCube and explore the constraints on models if GRB neutrinos remain undetected despite improved sensitivity. Our findings reveal that if the effective area of a future neutrino detector can be enhanced by a factor of 10 compared to IceCube IC 86-II, there is a high likelihood of detecting neutrinos from a GRB 221009A-like event, even in the context of the ICMART model, which exhibits the lowest efficiency in neutrino production. With such an advanced detector (enhanced by a factor of 10) and 5–10 yr of data accumulation, neutrinos from stacked GRBs should be identifiable, or several popular models for GRB prompt emission (e.g., the dissipative photosphere model and internal shock model) could be effectively ruled out.}, archive = {J_ApJ}, author = {Wenkang Lian and Shunke Ai and He Gao}, doi = {10.3847/1538-4357/add1db}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {79}, shortjournal = {The Astrophys. J.}, title = {Prospect of gamma-ray burst neutrino detection with enhanced neutrino detectors}, volume = {987}, year = {2025}, }
• (2025). Prestellar cores in turbulent clouds: Numerical modeling and evolution to collapse. ApJ, 987(1), 78. (www)

  @article{ , abstract = {A fundamental issue in star formation is understanding the precise mechanisms leading to the formation of prestellar cores and their subsequent gravitationally unstable evolution. To address this question, we carefully construct a suite of turbulent, self-gravitating numerical simulations, and analyze the development and collapse of individual prestellar cores. We show that the numerical requirements for resolving the sonic scale and internal structure of anticipated cores are essentially the same in self-gravitating clouds, calling for the number of cells per dimension to increase quadratically with the cloud’s Mach number. In our simulations, we follow the evolution of individual cores by tracking the region around each gravitational potential minimum over time. Evolution in nascent cores is toward increasing density and decreasing turbulence, and there is a wide range of critical density for initiating collapse. At a given spatial scale, the turbulence level also varies widely and tends to be correlated with density. By directly measuring the radial forces acting within cores, we identify a distinct transition to a state of gravitational runaway. We use our new theory for turbulent equilibrium spheres to predict the onset of each core’s collapse. Instability is expected when the critical radius becomes smaller than the tidal radius; we find good agreement with the simulations. Interestingly, the imbalance between gravity and opposing forces is only ∼20% during core collapse, meaning that this is a quasi-equilibrium rather than a freefall process. For most of their evolution, cores exhibit both subsonic contraction and transonic turbulence inherited from core-building flows; supersonic radial velocities accelerated by gravity only appear near the end of the collapse.}, archive = {J_ApJ}, author = {Sanghyuk Moon and Eve C. Ostriker}, doi = {10.3847/1538-4357/add477}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {78}, shortjournal = {The Astrophys. J.}, title = {Prestellar cores in turbulent clouds: Numerical modeling and evolution to collapse}, volume = {987}, year = {2025}, }
• (2025). Why is the star formation rate proportional to dense gas mass?. ApJ, 987(1), 77. (www)

  @article{ , abstract = {One of the most profound empirical laws of star formation is the Gao–Solomon relation, a linear correlation between the star formation rate (SFR) and the dense molecular gas mass. It is puzzling how the complicated physics in star formation results in this surprisingly simple proportionality. Using archival Herschel and Atacama Large Millimeter/submillimeter Array observations, we derived the masses of the most massive cores ( {M}_{{\rm{core}}}^{{\rm{\max }}} ) and masses of the gravitationally bound gas ( {M}_{{\rm{gas}}}^{{\rm{bound}}} ) in the parent molecular clouds for a sample of low-mass and high-mass star-forming regions. We discovered a significant correlation of \mathrm{log}({M}_{{\rm{core}}}^{{\rm{\max }}}/{M}_{\odot })=0.506\mathrm{log}({M}_{{\rm{gas}}}^{{\rm{bound}}}/{M}_{\odot })-0.32 . Our discovered {M}_{{\rm{core}}}^{{\rm{\max }}} – {M}_{{\rm{gas}}}^{{\rm{bound}}} correlation can be approximately converted to the Gao–Solomon relation if there is (1) a constant 30% efficiency of converting {M}_{{\rm{core}}}^{{\rm{\max }}} to the mass of the most massive star ( {m}_{{\rm{star}}}^{{\rm{\max }}} ), and (2) if the SFR and {m}_{{\rm{star}}}^{{\rm{\max }}} are tightly related through {\rm{log}}({\rm{SFR}}/({M}_{\odot }\,{{\rm{yr}}}^{-1}))=2.04{\rm{log}}({m}_{{\rm{star}}}^{max}/{M}_{\odot })-5.80 . Intriguingly, both requirements have been suggested by previous theoretical studies. Based on this result, we hypothesize that the Gao–Solomon relation is a consequence of combining the following three nontrivial relations (i) SFR versus {m}_{{\rm{star}}}^{{\rm{\max }}} , (ii) {m}_{{\rm{star}}}^{{\rm{\max }}} versus {M}_{{\rm{core}}}^{{\rm{\max }}} , and (iii) {M}_{{\rm{core}}}^{{\rm{\max }}} versus {M}_{{\rm{gas}}}^{{\rm{bound}}} . This finding may open a new possibility to understand the Gao–Solomon relation in an analytic sense.}, archive = {J_ApJ}, author = {Sihan Jiao and Fengwei Xu and Hauyu Baobab Liu and Yuxin Lin and Jingwen Wu and Zhi-Yu Zhang and Zhiqiang Yan and Di Li and Chao-Wei Tsai and Yongkun Zhang and Linjing Feng and Ke Wang and Zheng Zheng and Fanyi Meng and Hao Ruan and Fangyuan Deng and Keyun Su}, doi = {10.3847/1538-4357/add480}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {77}, shortjournal = {The Astrophys. J.}, title = {Why is the star formation rate proportional to dense gas mass?}, volume = {987}, year = {2025}, }
• (2025). Softness ratio of SWIFT gamma-ray bursts and relevant correlations. ApJ, 987(1), 76. (www)

  @article{ , abstract = {The properties of X-ray flashes (XRFs) and X-ray-rich gamma-ray bursts (XRRs) as compared with classical gamma-ray bursts (C-GRBs) have been widely discussed during the SWIFT era. It has been proposed that XRFs and XRRs are low-energy extensions of the gamma-ray burst (GRB) population, and therefore, they should follow similar correlations. To further examine this idea, we collect a sample of 303 GRBs detected by SWIFT over the past two decades, all of which have reliable redshifts and spectral parameters. The bursts are classified into XRFs, XRRs, and C-GRBs based on their softness ratio (SR), which is calculated by dividing the 25–50 keV fluence with the 50–100 keV fluence. A strong correlation is found among the isotropic energy E iso , peak luminosity L p , and rest-frame burst duration T 90,rest , i.e., {E}_{{\rm{iso}}}\propto {L}_{{\rm{p}}}^{0.88\pm 0.02}{T}_{90,{\rm{rest}}}^{0.58\pm 0.02} . Additionally, two tight three-parameter correlations involving SR and the rest-frame peak energy E p are also derived, i.e., {E}_{{\rm{p}}}\propto {E}_{{\rm{iso}}}^{0.20\pm 0.02}{{\rm{SR}}}^{-2.27\pm 0.15} and {E}_{{\rm{p}}}\propto {L}_{{\rm{p}}}^{0.17\pm 0.02}{{\rm{SR}}}^{-2.33\pm 0.14} . It is interesting to note that XRFs, XRRs, and C-GRBs all follow the above correlations. The implications of these correlations and their potential application in cosmology are discussed.}, archive = {J_ApJ}, author = {Fan Xu and Yong-Feng Huang and Liang Li and Jin-Jun Geng and Xue-Feng Wu and Song-Bo Zhang and Chen Deng and Chen-Ran Hu and Xiao-Fei Dong and Hao-Xuan Gao}, doi = {10.3847/1538-4357/add5e1}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {76}, shortjournal = {The Astrophys. J.}, title = {Softness ratio of SWIFT gamma-ray bursts and relevant correlations}, volume = {987}, year = {2025}, }
• (2025). Milliarcsecond X-ray positions and X-ray varstrometry for the strongly lensed active galactic nucleus HE 0435-1223. ApJ, 987(1), 75. (www)

  @article{ , abstract = {Active galactic nuclei (AGN) are some of the most powerful objects in the Universe. For this reason, they can be observed up to high redshifts ( z ), giving valuable insights into the evolution of our Universe. However, high- z AGN are too distant to be spatially resolved with current or upcoming X-ray facilities. In this paper, we show how we can exploit gravitationally lensed AGN to significantly increase spatial resolution even at high z . We combine astrometric data from Gaia DR3 with imaging from the Chandra X-ray Observatory of the quadruply lensed quasar HE 0435-1223 to measure for the first time possible offsets between the optical and the X-ray emissions. We measure the X-ray source position for HE 0435-1223 within a 1 σ quasi-elliptical region of 0.5 × 1.3 milliarcsecond (mas), about 150 pc 2 at the redshift of the source ( z = 1.689). We find evidence for the X-ray emission being offset by a projected 3 mas from the Gaia (optical) emission. The positional offset is most likely associated with a portion of the X-ray emission arising from an X-ray jet or outflow. We also discuss how this method can be used to indicate the presence of a binary/offset AGN system.}, archive = {J_ApJ}, author = {Alysa Rogers and Daniel Schwartz and Cristiana Spingola and Anna Barnacka}, doi = {10.3847/1538-4357/add71a}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {75}, shortjournal = {The Astrophys. J.}, title = {Milliarcsecond X-ray positions and X-ray varstrometry for the strongly lensed active galactic nucleus HE 0435-1223}, volume = {987}, year = {2025}, }
• (2025). Galaxy zoo CEERS: Bar fractions up to z ∼ 4.0. ApJ, 987(1), 74. (www)

  @article{ , abstract = {We study the evolution of the bar fraction in disk galaxies between 0.5 < z < 4.0 using multiband colored images from JWST Cosmic Evolution Early Release Science Survey (CEERS). These images were classified by citizen scientists in a new phase of the Galaxy Zoo (GZ) project called GZ CEERS. Citizen scientists were asked whether a strong or weak bar was visible in the host galaxy. After considering multiple corrections for observational biases, we find that the bar fraction decreases with redshift in our volume-limited sample ( n = 398); from 2{5}_{-4}^{+6} % at 0.5 < z < 1.0 to {3}_{-1}^{+6} % at 3.0 < z < 4.0. However, we argue it is appropriate to interpret these fractions as lower limits. Disentangling real changes in the bar fraction from detection biases remains challenging. Nevertheless, we find a significant number of bars up to z = 2.5. This implies that disks are dynamically cool or baryon dominated, enabling them to host bars. This also suggests that bar-driven secular evolution likely plays an important role at higher redshifts. When we distinguish between strong and weak bars, we find that the weak bar fraction decreases with increasing redshift. In contrast, the strong bar fraction is constant between 0.5 < z < 2.5. This implies that the strong bars found in this work are robust long-lived structures, unless the rate of bar destruction is similar to the rate of bar formation. Finally, our results are consistent with disk instabilities being the dominant mode of bar formation at lower redshifts, while bar formation through interactions and mergers is more common at higher redshifts.}, archive = {J_ApJ}, author = {Tobias Géron and R. J. Smethurst and Hugh Dickinson and L. F. Fortson and Izzy L. Garland and Sandor Kruk and Chris Lintott and Jason Shingirai Makechemu and Kameswara Bharadwaj Mantha and Karen L. Masters and David O’Ryan and Hayley Roberts and B. D. Simmons and Mike Walmsley and Antonello Calabrò and Rimpei Chiba and Luca Costantin and Maria R. Drout and Francesca Fragkoudi and Yuchen Guo and B. W. Holwerda and Shardha Jogee and Anton M. Koekemoer and Ray A. Lucas and Fabio Pacucci}, doi = {10.3847/1538-4357/add7d0}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {74}, shortjournal = {The Astrophys. J.}, title = {Galaxy zoo CEERS: Bar fractions up to z ∼ 4.0}, volume = {987}, year = {2025}, }
• (2025). Origin of the IRAS vela shell: New insights from 3D dust mapping. ApJ, 987(1), 73. (www)

  @article{ , abstract = {The IRAS Vela Shell (IVS) is a structure of enhanced far-IR (FIR) emission located toward the Gum Nebula, a prominent region of H α emission in the local Milky Way shaped by various galactic stellar feedback over the past several million years. We constrain the 3D spatial geometry of the IVS using a parsec-resolution 3D dust map and contextualize it within the broader Gum Nebula. Our analysis reveals a dense, bowl-like IVS structure below the Galactic plane, with a more diffuse component above. We obtain a total shell mass of 5.{1}_{-2.4}^{+2.4}\times 1{0}^{4}\,{{M}}_{\odot } and, incorporating previous studies on shell expansion, a momentum of 6.{0}_{-3.4}^{+4.7}\times 1{0}^{5}\,{{M}}_{\odot }\,{\rm{km}}\,{{\rm{s}}}^{-1} . We find a spatial correlation between the morphology of the dust-traced IVS and the Gum Nebula’s H α emission when projected onto the sky. We quantify contributions of feedback from stellar winds, an expanding H ii region, and supernovae to the IVS formation, finding that stellar winds are subdominant. Our momentum analysis shows that both an H ii region and supernova feedback could drive the shell’s expansion. Using astrometric constraints from Gaia and Hipparcos, we trace back nearby feedback sources and find that the massive stars γ 2 Velorum and ζ Puppis are currently within the IVS, producing enough ionizing luminosity to form an H ii region of comparable size. Alternatively, if the IVS’ momentum is primarily driven by supernovae, one to two events would be required. We also identify several young massive clusters that could have hosted supernovae within the past 3 Myr.}, archive = {J_ApJ}, author = {Bore Annie Gao and Catherine Zucker and Tirupati Kumara Sridharan and Cameren Swiggum and Shmuel Bialy and Theo J. O’Neill and J. E. G. Peek and Luciana Bianchi and Robert Benjamin and Lewis McCallum and Alyssa Goodman and João Alves and Charles Lada and Gordian Edenhofer and Rowan Smith and Elizabeth Watkins and Kenneth Wood and Doni Anderson}, doi = {10.3847/1538-4357/add7d8}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {73}, shortjournal = {The Astrophys. J.}, title = {Origin of the IRAS vela shell: New insights from 3D dust mapping}, volume = {987}, year = {2025}, }
• (2025). Mass ratio dependence of strong guide field reconnection based on a gyrokinetic electron and fully kinetic ion particle simulation. ApJ, 987(1), 72. (www)

  @article{ , abstract = {Magnetic reconnection under a strong guide field {B}_{G}/{B}_{y0}\gg 1 , as in solar wind and laboratory plasmas, is investigated using the gyrokinetic electron and fully kinetic ion (GeFi) particle simulation model, where {B}_{y0} is the antiparallel component of the magnetic field and {B}_{G} is the guide field. Cases with two-dimensional force-free current sheets are presented in conditions with a large guide field and low plasma beta, similar to the reconnection events associated with solar flares. To gain insights into how the ion-to-electron mass ratio ( {m}_{i}/{m}_{e} ) and normalized guide field ( {B}_{G}/{B}_{y0} ) affect the rate and structures of reconnection, we present a series of simulations by varying {m}_{i}/{m}_{e} from 100 to 1836 and {B}_{G}/{B}_{y0} from 5 to 15. First, linear eigenmode analysis is performed for the collisionless tearing mode. We find that the eigenmode structure and growth rate of the tearing mode obtained from the GeFi simulation are in excellent agreement with the eigenmode theory for strong {B}_{G} . Subsequently, we employ GeFi simulations to explore the reconnection rate and current sheet structure across a wide range of {m}_{i}/{m}_{e} and {B}_{G}/{B}_{y0} . Intriguingly, it is found that the reconnection rate is insensitive to {m}_{i}/{m}_{e} . The growth rate of the tearing mode, however, has a strong dependence on {m}_{i}/{m}_{e} . The reconnection rate exhibits a clear increase with decreasing {B}_{G}/{B}_{y0} and also strongly depends on {B}_{G}/{B}_{y0} . Furthermore, the length of the electron diffusion region increases with {m}_{i}/{m}_{e} . These findings advance understanding of the reconnection dynamics in solar flares and other astrophysical phenomena.}, archive = {J_ApJ}, author = {Zhifang Guo and Yu Lin and Xueyi Wang and Aimin Du}, doi = {10.3847/1538-4357/adda34}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {72}, shortjournal = {The Astrophys. J.}, title = {Mass ratio dependence of strong guide field reconnection based on a gyrokinetic electron and fully kinetic ion particle simulation}, volume = {987}, year = {2025}, }
• (2025). Magnetized accretion onto neutron stars: From photon-trapped to neutrino-cooled flows. ApJ, 987(1), 71. (www)

  @article{ , abstract = {When a neutron star (NS) intercepts gas from a nondegenerate star, e.g., in a tidal disruption event, a common-envelope phase, or the collapsing core of a massive star, photons become trapped in the hot flow around the NS. This gas forms a radiatively inefficient accretion flow (RIAF) until the density and temperature close to the NS surface grow large enough for binding energy to be converted to neutrinos. Here, we present three-dimensional, general-relativistic, magnetohydrodynamic simulations of accretion onto a nonrotating, unmagnetized NS. These connect, for the first time, an extended accretion disk with a self-consistent hydrostatic atmosphere around the star. The impact of different seed magnetic fields and accretion rates is studied by approximating the radiation-pressure-dominated flow as an ideal gas with an adiabatic index of 4/3, coupled to a variable neutrino emissivity. At low accretion rates, the hydrostatic atmosphere shows slow rotation and weak magnetization, transitioning to an outer RIAF structure. A toroidal magnetic field mediates the inward flow of energy and angular momentum through the atmosphere, which reaches a steady state when neutrino emission balances the accretion power. We develop a one-dimensional analytical model connecting these results with more general initial conditions and describing the main features of the flow. Our results have implications for the spin and mass evolution of hypercritically accreting NSs.}, archive = {J_ApJ}, author = {Luciano Combi and Christopher Thompson and Daniel M. Siegel and Alexander Philippov and Bart Ripperda}, doi = {10.3847/1538-4357/addc57}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {71}, shortjournal = {The Astrophys. J.}, title = {Magnetized accretion onto neutron stars: From photon-trapped to neutrino-cooled flows}, volume = {987}, year = {2025}, }
• (2025). Quantifying the velocity anisotropy profile of galaxy clusters using the uchuu cosmological simulation. ApJ, 987(1), 70. (www)

  @article{ , abstract = {Galaxy clusters are powerful laboratories for studying both cosmic structure formation and galaxy evolution. We present a comprehensive analysis of the velocity anisotropy profile, β ( r ), in galaxy clusters using the Uchuu-UniverseMachine mock galaxy catalog, which combines the large-volume Uchuu N -body simulation with the UniverseMachine galaxy formation model. Focusing on clusters with \mathrm{log}{M}_{200}\geqslant 13.9\,[{h}^{-1}{M}_{\odot }] up to redshift z = 1.5, we investigate the behavior of β ( r ) as a function of clustercentric radius, mass, and redshift. We find that β ( r ) exhibits a universal shape: it rises from isotropic values near the cluster core, peaks at ∼1.7 R 200 , declines around 3.4 R 200 due to orbital mixing, and increases again in the outskirts, due to the dominance of first-infalling galaxies. Our results show that more massive clusters have higher radial anisotropy and larger peak β values. Moreover, β ( r ) evolves with redshift, with high-redshift clusters displaying more radially dominated orbits and enhanced infall motions. We further derive redshift-dependent power-law scaling relations between M 200 and key physical radii—hydrostatic ( R hs ), infall ( {R}_{\inf } ), and turnaround ( R ta ). These findings offer a robust theoretical framework for interpreting the dynamical properties of observed galaxy clusters and provide key insights into the evolution of their dynamical state over cosmic time.}, archive = {J_ApJ}, author = {Mohamed H. Abdullah and Raouf H. Mabrouk and Tomoaki Ishiyama and Gillian Wilson and Magdy Y. Amin and Elamira Hend Khattab and H. I. Abdel Rahman}, doi = {10.3847/1538-4357/adde4b}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {70}, shortjournal = {The Astrophys. J.}, title = {Quantifying the velocity anisotropy profile of galaxy clusters using the uchuu cosmological simulation}, volume = {987}, year = {2025}, }
• (2025). High-velocity molecular clouds in m83. ApJ, 987(1), 69. (www)

  @article{ , abstract = {High-velocity clouds (HVCs), which are gas clouds moving at high velocity relative to the galactic disk, may play a critical role in galaxy evolution, potentially supplying gas to the disk and triggering star formation. In this study, we focus on the nearby face-on barred spiral galaxy M83, where high-spatial-resolution, high-sensitivity CO(1–0) data are available. We identified molecular clouds and searched for clouds with velocities deviating by more than 50 km s −1 from the disk velocity field as HVCs. A total of 10 HVCs were detected—9 redshifted and 1 blueshifted—clearly highlighting an asymmetry in their velocity distribution. These HVCs have radii of 30–80 pc, masses on the order of 10 5 M ⊙ , and velocity dispersions of 3–20 km s −1 , displaying a tendency toward higher velocity dispersion compared to disk molecular clouds in M83. Most of the HVCs do not overlap with the candidates of supernova remnants, and the energy needed to drive HVCs at such high velocities exceeds single supernova energy. Together with the asymmetry in their velocity distribution, we thus conclude that most of the HVCs found in this study are inflow from outside the M83’s disk.}, archive = {J_ApJ}, author = {Maki Nagata and Fumi Egusa and Fumiya Maeda and Kazuki Tokuda and Kotaro Kohno and Kana Morokuma-Matsui and Jin Koda}, doi = {10.3847/1538-4357/addab7}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {69}, shortjournal = {The Astrophys. J.}, title = {High-velocity molecular clouds in m83}, volume = {987}, year = {2025}, }
• (2025). Flickers, bursts, and dips: Detecting rapid variability with the g(2) autocorrelation function. ApJ, 987(1), 68. (www)

  @article{ , abstract = {Rapid optical transient events can be hard to detect because of the limited number of photons they produce. I discuss a method of inferring the presence of fast, chaotic variability in photometry using the normalized autocorrelation function, what is called g (2) in quantum optics. The variability’s signature is a bump in the function at short lags. No periodicity is needed for the method to work. Versions of this method are attested in stellar variability studies, but its uses in some other subfields apparently have not been realized. I calculate expected signal-to-noise ratios with shot noise and scintillation. This method could be used to find unknown phenomena, particularly submillisecond optical variability. I present simple models of three example use cases: a flickering artificial “lantern” near a host Sun, optical microbursts from the Crab pulsar, and frequent irregular transits of a star by cometary bodies.}, archive = {J_ApJ}, author = {Brian C. Lacki}, doi = {10.3847/1538-4357/add151}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {68}, shortjournal = {The Astrophys. J.}, title = {Flickers, bursts, and dips: Detecting rapid variability with the g(2) autocorrelation function}, volume = {987}, year = {2025}, }
• (2025). The thermal index of neutron-star matter in the virial approximation. ApJ, 987(1), 67. (www)

  @article{ , abstract = {Motivated by gravitational-wave observations of binary neutron-star mergers, we study the thermal index of low-density, high-temperature dense matter. We use the virial expansion to account for nuclear interaction effects. We focus on the region of validity of the expansion, which reaches 10 −3 fm −3 at T = 5 MeV up to almost saturation density at T = 50 MeV. In pure neutron matter, we find an analytical expression for the thermal index, and show that it is nearly density and temperature independent, within a fraction of a percent of the noninteracting, nonrelativistic value of Γ th ≈ 5/3. When we incorporate protons, electrons, and photons, we find that the density and temperature dependence of the thermal index changes significantly. We predict a smooth transition between an electron-dominated regime with Γ th ≈ 4/3 at low densities to a neutron-dominated region with Γ th ≈ 5/3 at high densities. This behavior is by and large independent of the proton fraction and is not affected by nuclear interactions in the region where the virial expansion converges. We model this smooth transition analytically and provide a simple but accurate parameterization of the inflection point between these regimes. When compared to tabulated realistic models of the thermal index, we find an overall agreement at high temperatures that weakens for colder matter. The discrepancies can be attributed to the missing contributions of nuclear clusters. The virial approximation provides a clear and physically intuitive framework for understanding the thermal properties of dense matter, offering a computationally efficient solution that makes it particularly well suited for the regimes relevant to neutron-star binary remnants.}, archive = {J_ApJ}, author = {Giuseppe Rivieccio and Adriana Nadal-Matosas and Arnau Rios and Milton Ruiz}, doi = {10.3847/1538-4357/add3ed}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {67}, shortjournal = {The Astrophys. J.}, title = {The thermal index of neutron-star matter in the virial approximation}, volume = {987}, year = {2025}, }
• (2025). J1406+0102: A dust-obscured galaxy hiding a super-eddington accretion system with bright radio emission. ApJ, 987(1), 66. (www)

  @article{ , abstract = {Recent high- z quasar observations strongly indicate that super-Eddington accretion is a crucial phase to describe the presence of supermassive black holes (SMBHs) with M BH ≳ 10 9 M ⊙ at z ≳ 7. Motivated by theoretical predictions that the super-Eddington phase efficiently produces outflows and bright jets in radio bands, we identify a super-Eddington radio-loud dust-obscured galaxy (DOG) J1406+0102 at z = 0.2367. This source is discovered by cross-matching the infrared-bright DOGs of A. Noboriguchi et al. with the Very Large Array/Far-Infrared and Submillimetre Telescope 1.4 GHz radio survey data and the Sloan Digital Sky Survey optical spectral catalog. J1406+0102 shows broad components in the Balmer lines, and by assuming that those lines are from the broad-line region, they give black hole (BH) mass estimations of \mathrm{log}\,({M}_{{\rm{BH}}}/{M}_{\odot })=7.30\pm 0.25 . Combined with an active galactic nucleus (AGN) luminosity of \mathrm{log}({L}_{\mathrm{bol},[{\rm{O}}\,\mathrm{III}]}/\mathrm{erg}\,{{\rm{s}}}^{-1})=45.91\pm 0.38 estimated from the intrinsic [O iii ] luminosity, this implies a super-Eddington accretion rate of λ Edd ≃ 3. We show that (1) J1406+0102 shows strong AGN feedback, with the [O i ii ] outflow velocity exceeding the escape velocity of the host galaxy halo and a kinetic efficiency of ≈8%, sufficient to quench the host galaxy; (2) its expected growth trajectory places it on an overmassive BH track; and (3) if representative of radio-loud DOGs, such sources can contribute significantly to the high-energy (≳100 TeV) cosmic neutrino background.}, archive = {J_ApJ}, author = {Hikaru Fukuchi and Kohei Ichikawa and Masayuki Akiyama and Shigeo S. Kimura and Yoshiki Toba and Kohei Inayoshi and Akatoki Noboriguchi and Toshihiro Kawaguchi and Xiaoyang Chen and Itsna K. Fitriana}, doi = {10.3847/1538-4357/add478}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {66}, shortjournal = {The Astrophys. J.}, title = {J1406+0102: A dust-obscured galaxy hiding a super-eddington accretion system with bright radio emission}, volume = {987}, year = {2025}, }
• (2025). Revealing the χeff–q correlation among coalescing binary black holes and tentative evidence for AGN-driven hierarchical mergers. ApJ, 987(1), 65. (www)

  @article{ , abstract = {The origin of the correlation between the effective spins ( χ eff ) and mass ratios ( q ) of LIGO–Virgo–KAGRA’s binary black holes (BBHs) is still an open question. Motivated by the recent identification of two subpopulations of the BBHs, in this work we investigate the potential χ eff – q correlation for each subpopulation. Surprisingly, the χ eff – q correlation either significantly weakens or disappears for the low-mass subpopulation if we introduce a second χ eff distribution for the high-mass subpopulation, which likely originates from hierarchical mergers. This suggests that the χ eff – q correlation in the overall population can be explained by the superposition of two distinct subpopulations. We find Bayesian evidence strongly favoring two separate χ eff distributions over a single mass ratio–dependent distribution, with Bayes factors \mathrm{ln}{ \mathcal B }\gt 4.2 . The first subpopulation has a narrow χ eff distribution peaking at ∼0.05, whose primary mass function shows a rapid decline beyond ∼40 M ⊙ , in agreement with first-generation BBHs. The second χ eff distribution is broad and peaks at μ χ ,2 ∼ 0.4, aligning with predictions for hierarchical mergers in active galactic nucleus (AGN) disks. However, we cannot exclude negative χ eff values in the second subpopulation, suggesting that hierarchical mergers might occur both in AGN disks and stellar clusters. Furthermore, the inferred second χ eff distribution might alternatively arise from other formation channels, such as stable mass transfer or chemically homogeneous evolution, if not interpreted as hierarchical mergers.}, archive = {J_ApJ}, author = {Yin-Jie Li and Yuan-Zhu Wang and Shao-Peng Tang and Tong Chen and Yi-Zhong Fan}, doi = {10.3847/1538-4357/add535}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {65}, shortjournal = {The Astrophys. J.}, title = {Revealing the χeff–q correlation among coalescing binary black holes and tentative evidence for AGN-driven hierarchical mergers}, volume = {987}, year = {2025}, }
• (2025). The correspondence between leaky-box and diffusion models of cosmic-ray propagation. ApJ, 987(1), 64. (www)

  @article{ , abstract = {The leaky-box model and the attendant concept of path-length distribution of cosmic rays were invented in the mid-1960s. Even though versatile computational packages such as GALPROP and DRAGON with the diffusion approach are now available for analyzing cosmic-ray data, the concepts of the leaky box and path-length distribution continue to be adopted extensively. We show here mathematically that there is a close correspondence between the two approaches: the path lengths or resident times of the leaky-box models are similar to the “impulse response functions” of complex dynamical systems and are intuitively transparent. The results provided by the leaky-box model are valid when used judiciously.}, archive = {J_ApJ}, author = {Ramanath Cowsik and Dawson Huth}, doi = {10.3847/1538-4357/add6a3}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {64}, shortjournal = {The Astrophys. J.}, title = {The correspondence between leaky-box and diffusion models of cosmic-ray propagation}, volume = {987}, year = {2025}, }
• (2025). NuSTAR and XMM-newton observations of PSR j1930+1852 and its pulsar wind nebula. ApJ, 987(1), 63. (www)

  @article{ , abstract = {Synchrotron X-ray emission from a pulsar wind nebula (PWN) is a sensitive probe of its magnetic field and high-energy particle population. Here we analyze contemporaneous NuSTAR and XMM - Newton observations of the PWN G54.1+0.3, powered by pulsar PSR J1930+1852. We also present a preliminary timing analysis of the central pulsar PSR J1930+1852 and analyze its X-ray pulse profiles in different energy bands. We detect X-ray emission from the combined pulsar and PWN system up to ≈70 keV, while emission from the PWN itself has been detected up to ≈30 keV, with a photon index Γ increasing from ∼1.9 to ∼2.4 with photon energy between 3 and 30 keV. PWN G54.1+0.3’s X-ray spectrum is consistent with a broken power law, with break energy E break ≈ 5 keV, consistent with synchrotron cooling of a single power-law particle spectrum. The best-fit broadband spectral energy distribution model after the inclusion of this new spectral data indicates a maximum particle energy {E}_{{\rm{\max }}}\sim 400 TeV. We discuss PSR J1930+1852 and PWN G54.1+0.3 in the context of other PWNe powered by young energetic pulsars.}, archive = {J_ApJ}, author = {J. A. J. Alford and G.-B. Zhang and J. D. Gelfand}, doi = {10.3847/1538-4357/add92e}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {63}, shortjournal = {The Astrophys. J.}, title = {NuSTAR and XMM-newton observations of PSR j1930+1852 and its pulsar wind nebula}, volume = {987}, year = {2025}, }
• (2025). Neutrino anisotropy as a probe of extreme astrophysical accelerators. ApJ, 987(1), 62. (www)

  @article{ , abstract = {We predict that neutrino sources following the matter distribution of the Universe result in an anisotropy in the neutrino sky imprinted by the local large-scale structure (LSS). We calculate the level of this anisotropy and explore how it depends on the cosmological evolution of neutrino sources. We show how the level of anisotropy can be amplified when a cutoff in the neutrino spectrum is considered, introducing an effective neutrino horizon. This effect might allow for future neutrino detectors to measure a neutrino anisotropy associated with the local LSS. Measurement of the level of this anisotropy along with features of the neutrino spectrum will allow observers to constrain the cosmological evolution of neutrino sources, which at ultra-high energies (UHEs) are also expected to be the sources of UHE cosmic rays.}, archive = {J_ApJ}, author = {Marco Stein Muzio and Noémie Globus}, doi = {10.3847/1538-4357/add931}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {62}, shortjournal = {The Astrophys. J.}, title = {Neutrino anisotropy as a probe of extreme astrophysical accelerators}, volume = {987}, year = {2025}, }
• (2025). Resolved ALMA [C ii] 158 μm observations at cosmic noon: Interstellar medium structure and dynamics of the starbursting QSO SDSS j1000. ApJ, 987(1), 61. (www)

  @article{ , abstract = {We present spatially resolved Atacama Large Millimeter/submillimeter Array Band 9 observations of the [C ii ] 158 μ m fine structure line from an optically selected quasar, SDSS J100038.01+020822.4 (J1 000 ), at z = 1.8275. By utilizing [O i ] 63 μ m line observations from Herschel/PACS and constructing a detailed dust spectral energy distribution using Herschel and Spitzer archival imaging data, we show that the [C ii ] line emission is well explained by a photodissociation region (PDR) model, in which the emission arises from the surfaces of molecular clouds exposed to far-UV radiation fields ∼5 × 10 3 times the local interstellar radiation field ( G 0 ). We find a factor of 30 variation in spatially resolved [C ii ]/far-IR continuum across the source, which is explained by the reduced fraction of cooling via [C ii ] line emission at such high far-UV field strengths. By matching the derived PDR parameters to the observed far-IR line and continuum intensities we derive cloud size scales and find that typical cloud radii in J1000 are ∼3.5 pc, perhaps indicating an interstellar medium that is highly fractured due to intense star formation activity. We model the galaxy dynamically and find that the [C ii ] emission is contained within a compact, dynamically cold disk with v / σ = 6.2, consistent with the IllustrisTNG50 cosmological simulation. We also report the discovery of a companion galaxy to J1 000 confirmed by the detection of [C ii ] and use recently obtained JWST/NIRCam imaging of the system to argue for J1 000 being an interacting system. With total stellar mass ∼ 1.5 × 10 10 M ⊙ and main-component dynamical mass ≳ 10 11 M ⊙ , the J1 000 system is a progenitor to the most massive galaxies seen in the local Universe.}, archive = {J_ApJ}, author = {Christopher Rooney and Bo Peng and Amit Vishwas and Gordon Stacey and Thomas Nikola and Cody Lamarche and Catie Ball and Carl Ferkinhoff and Drew Brisbin and Steven Hailey-Dunsheath}, doi = {10.3847/1538-4357/add9a1}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {61}, shortjournal = {The Astrophys. J.}, title = {Resolved ALMA [C ii] 158 μm observations at cosmic noon: Interstellar medium structure and dynamics of the starbursting QSO SDSS j1000}, volume = {987}, year = {2025}, }
• (2025). On the very bright dropouts selected using the james webb space telescope NIRCam instrument. ApJ, 987(1), 60. (www)

  @article{ , abstract = {The selection of candidate high-redshift galaxies using the dropout technique targeting the Lyman-break signature sometimes yields very bright objects that are too luminous to be easily explained if they are indeed at the expected redshifts. Here, we present systematic study of very bright dropouts selected through successive bands of the NIRCam instrument onboard the James Webb Space Telescope (JWST). Using the public NIRCam data in four blank fields over 500 arcmin 2 , 300 such objects were found. They have F356W magnitudes <25.1 mag or <26.0 mag depending on the dropout passband, and the majority of them (>80%) have very red F115W − F356W colors >2.0 mag, qualifying them as “extremely red objects.” We focus on 137 objects that also have mid-infrared observations from the JWST MIRI instrument. Their spectral energy distribution analysis shows that these objects are dominated by low-redshift ( z ∼ 1–4) galaxies (≳67%). However, a non-negligible fraction (≳7%) could be at high redshifts. Seven of our objects have secure spectroscopic redshifts from JWST NIRSpec identifications, and the results confirm this picture: while six are low-redshift galaxies ( z ≈ 3), one is a known galaxy at z = 8.679 (with M UV = −22.4 mag and stellar mass M * = 10 9.1 M ⊙ ) recovered in our sample. In light of recent theoretical models on early galaxy formation, this confirmed high-redshift galaxy does not pose a challenge. However, since our sample contains very luminous high-redshift candidates in the regime still underexplored ( M UV ≤ −23 mag and M * > 10 10.5 M ⊙ ), spectroscopic identifications are necessary to ensure they do not create tension with these new models.}, archive = {J_ApJ}, author = {Bangzheng Sun and Haojing Yan}, doi = {10.3847/1538-4357/addbe0}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {60}, shortjournal = {The Astrophys. J.}, title = {On the very bright dropouts selected using the james webb space telescope NIRCam instrument}, volume = {987}, year = {2025}, }
• (2025). New tests of the cosmic distance duality relation with DESI 2024 baryon acoustic oscillation observations. ApJ, 987(1), 58. (www)

  @article{ , abstract = {In this paper, we test the cosmic distance duality relation (CDDR), as required by the Etherington reciprocity theorem, which connects the angular diameter distance and the luminosity distance via the relation D L ( z ) = D A ( z )(1 + z ) 2 . Our analysis is based on the latest baryon acoustic oscillation (BAO) measurements provided by the Dark Energy Survey (DES), the Baryon Oscillation Spectroscopic Survey/Extended BOSS, and the Dark Energy Spectroscopic Instrument surveys. Specifically, an unbiased test of the CDDR is performed through a novel, model-independent method inspired by the two-point diagnostic approach, with DES-SN 5YR and Pantheon type Ia supernova (SN Ia) sample reconstructed using the Artificial Neural Network technique. This methodology effectively eliminates all nuisance parameters, including the sound horizon scale r d from BAO and the absolute magnitude M B from SN Ia. A set of N − 1 independent CDDR ratios η ij are constructed for statistical analysis. At the current observational level, no significant deviation from the CDDR is observed at low redshifts, whereas we find positive evidence (>2 σ confidence level) of deviation from the CDDR at two high redshifts ( z = 2.33 and z = 2.334). Therefore, our results confirm that the BAO measurement provides a powerful tool to test such a fundamental relation in modern cosmology.}, archive = {J_ApJ}, author = {Qiumin Wang and Shuo Cao and Jianyong Jiang and Kaituo Zhang and Xinyue Jiang and Tonghua Liu and Chengsheng Mu and Dadian Cheng}, doi = {10.3847/1538-4357/ade2ce}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {58}, shortjournal = {The Astrophys. J.}, title = {New tests of the cosmic distance duality relation with DESI 2024 baryon acoustic oscillation observations}, volume = {987}, year = {2025}, }
• (2025). Properties of slow magnetoacoustic waves observed simultaneously using hi-C 2.1 and AIA. ApJ, 987(1), 57. (www)

  @article{ , abstract = {Propagating slow magnetoacoustic waves are commonly observed in different coronal structures but are most prominent in active region fan loops. Their rapid damping with damping lengths of the order of a wavelength has been investigated in the past by several authors. Although different physical mechanisms have been proposed, significant discrepancies between the theory and observations remain. Recent high-resolution observations captured simultaneously by two different instruments reveal distinct damping lengths for slow magnetoacoustic waves, although their passbands are similar. These results suggest a possible contribution of instrumental characteristics to the measurement of damping lengths. Here, we analyze the behavior of slow waves using a different pair of instruments in order to check the prevalence of such results. In particular, the cotemporal observations of active region NOAA AR 12712 by the High-resolution Coronal Imager (Hi-C 2.1; Hi-C) and the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO) are utilised. The estimated oscillation periods of slow magnetoacoustic waves identified from these data are 2.7 ± 0.2 minutes from SDO/AIA and 2.8 ± 1.2 minutes from Hi-C 2.1. The corresponding propagation speeds are found to be 46.0 ± 1.7 and 48.1 ± 0.6 km s −1 , respectively. Damping lengths were calculated by two different methods, the phase tracking method (PTM) and the Amplitude Tracking Method (ATM). The obtained values from the PTM are 4.0 ± 2.1 and 4.1 ± 0.3 Mm, while those from the ATM are 3.4 ± 1.0 and 3.7 ± 0.1 Mm, respectively, for the AIA and Hi-C data. Our results do not indicate any notable difference in damping lengths between these instruments.}, archive = {J_ApJ}, author = {Suraj K. Tripathy and S. Krishna Prasad and D. Banerjee}, doi = {10.3847/1538-4357/ade3c8}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {57}, shortjournal = {The Astrophys. J.}, title = {Properties of slow magnetoacoustic waves observed simultaneously using hi-C 2.1 and AIA}, volume = {987}, year = {2025}, }
• (2025). Kilonova emissions from neutron star merger remnants: Implications for the nuclear equation of state. ApJ, 987(1), 56. (www)

  @article{ , abstract = {Multimessenger observations of binary neutron star mergers can provide valuable information on the nuclear equation of state (EOS). Here, we investigate the extent to which electromagnetic observations of the associated kilonovae allow us to place constraints on the EOS. For this, we use state-of-the-art three-dimensional general-relativistic magnetohydrodynamics simulations and detailed nucleosynthesis modeling to connect properties of observed light curves to properties of the accretion disk, and hence, the EOS. Using our general approach, we use multimessenger observations of GW170817/AT2017gfo to study the impact of various sources of uncertainty on inferences of the EOS. We constrain the radius of a 1.4 M ⊙ neutron star to lie within 10.30 ≤ R 1.4 ≤ 13.0 km and the maximum mass to be M TOV ≤ 3.06 M ⊙ .}, archive = {J_ApJ}, author = {Kelsey A. Lund and Rahul Somasundaram and Gail C. McLaughlin and Jonah M. Miller and Matthew R. Mumpower and Ingo Tews}, doi = {10.3847/1538-4357/add148}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {56}, shortjournal = {The Astrophys. J.}, title = {Kilonova emissions from neutron star merger remnants: Implications for the nuclear equation of state}, volume = {987}, year = {2025}, }
• (2025). Wave–Particle interaction in the upstream of interplanetary coronal mass ejection shocks. ApJ, 987(1), 55. (www)

  @article{ , abstract = {Shocks associated with interplanetary coronal mass ejections are known to energize charged particles and give rise to solar energetic particles. Many of these energetic particles move ahead of the shock to create a foreshock region. The foreshock region primarily consists of solar wind plasma, exhibiting turbulent velocity and magnetic fields. Such turbulent behavior results from inherent solar wind turbulence modified by energetic particles. We analyze magnetic field data from six such ICME shocks observed by the Wind spacecraft. The analysis of the shock upstream shows that the magnetic power spectral density (PSD) maintains a power-law slope of −5/3. We also identify clear intermittent peaks in the PSD. After characterizing these peaks, we investigate various possibilities for their generation. Our analysis indicates that these peaks in the PSD are due to the resonant interaction of Alfvén waves with the bulk solar wind protons and protons with energy up to 10 keV. However, evidence of Alfvén wave interaction with highly energetic protons is not evident in our analysis, and we anticipate that such evidence is obscured by the prevailing solar wind turbulence in the shock upstream.}, archive = {J_ApJ}, author = {Shanwlee Sow Mondal and Aveek Sarkar and Sofiane Bourouaine}, doi = {10.3847/1538-4357/add3f0}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {55}, shortjournal = {The Astrophys. J.}, title = {Wave–Particle interaction in the upstream of interplanetary coronal mass ejection shocks}, volume = {987}, year = {2025}, }
• (2025). Non-LTE synthetic observables of a multidimensional model of type ia supernovae. ApJ, 987(1), 54. (www)

  @article{ , abstract = {Many promising explosion models for the elusive origin of Type Ia supernovae (SNe Ia) ultimately fail to completely reproduce a number of observed properties of these events. One limiting factor for many of these models is the use of the local thermodynamic equilibrium (LTE) assumption in the calculation of their synthetic observables, which has been shown to prevent the accurate prediction of a number of fundamental features of SNe Ia. The inclusion of high-accuracy non-LTE physics, however, increases computational cost and complexity such that multidimensional non-LTE calculations are often unfeasible, which can be problematic for models that are inherently multidimensional. In this work, we conduct radiative transfer calculations using 1D profiles that each correspond with a line of sight from an asymmetric, 2D SN Ia model. We find, in LTE, that the synthetic observables from these calculations efficiently reproduce those from the 2D calculation when an equivalence of bolometric luminosities between the 1D and 2D treatments is enforced. This allows for the accurate calculation of synthetic observables in 1D while still preserving multidimensional effects associated with the model. We leverage this to produce high-accuracy observables from 1D non-LTE calculations, showing significantly improved agreement with observations, including a roughly 50% reduction of B -band decline rate into congruence with the observed Phillips relation. Additionally, our non-LTE observables show Si ii λ 5972 pEWs that are much more similar to observations, while spanning multiple Branch classes, suggesting that some spectral classifications of SNe Ia may arise from line-of-sight effects.}, archive = {J_ApJ}, author = {Samuel J. Boos and Luc Dessart and Dean M. Townsley and Ken J. Shen}, doi = {10.3847/1538-4357/add400}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {54}, shortjournal = {The Astrophys. J.}, title = {Non-LTE synthetic observables of a multidimensional model of type ia supernovae}, volume = {987}, year = {2025}, }
• (2025). NuSTAR broadband X-ray observation of EF eri following its reawakening into a high accretion state. ApJ, 987(1), 53. (www)

  @article{ , abstract = {We present the first NuSTAR X-ray observation of EF Eri, a well-known polar system. The NuSTAR observation was conducted in conjunction with NICER shortly after EF Eri entered a high accretion state following an unprecedented period of low activity lasting 26 yr since 1997. NuSTAR detected hard X-ray emission up to 50 keV with an X-ray flux of 1.2 × 10 −10 erg s −1 cm −2 (3–50 keV). Folded X-ray lightcurves exhibit a single peak with ∼65% spin modulation throughout the 3–50 keV band. We found no evidence of quasiperiodic oscillation (QPO) signals at ν = 0.1–100 Hz with an upper limit on the QPO amplitude below 5% (90% confidence limit) at ν ∼ 0.5 Hz where the optical QPO was previously detected. Our 1D accretion column model, called MCVSPEC , was fitted to the NuSTAR spectral data, yielding an accurate white dwarf (WD) mass measurement of M = (0.55–0.63) M ⊙ . MCVSPEC accounts for radiative cooling by thermal bremsstrahlung and cyclotron emission, X-ray reflection off the WD surface, and a previously constrained range of the accretion column area. The derived WD mass range is in excellent agreement with the previous measurement of M = (0.55–0.65) M ⊙ in the optical band. This demonstrates a combination of broadband X-ray spectral analysis and the MCVSPEC model that can be employed in our ongoing NuSTAR observation campaign of other polars to determine their WD masses accurately.}, archive = {J_ApJ}, author = {Luke W. Filor and Kaya Mori and Gabriel Bridges and Charles J. Hailey and David A. H. Buckley and Gavin Ramsay and Axel D. Schwope and Valery F. Suleimanov and Michael T. Wolff and Kent S. Wood}, doi = {10.3847/1538-4357/add403}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {53}, shortjournal = {The Astrophys. J.}, title = {NuSTAR broadband X-ray observation of EF eri following its reawakening into a high accretion state}, volume = {987}, year = {2025}, }
• (2025). The absolute age of milky way globular clusters. ApJ, 987(1), 52. (www)

  @article{ , abstract = {Globular clusters (GCs) provide statistically significant coeval populations of stars spanning various evolutionary stages, allowing robust constraints on stellar evolution model parameters and ages. We analyze eight old Milky Way GCs with metallicities between [Fe/H] = −2.31 and −0.77 by comparing theoretical isochrone sets from the Dartmouth Stellar Evolution Program to Hubble Space Telescope (HST) observations. The theoretical isochrones include uncertainties introduced by 21 stellar evolution parameters such as convective mixing, opacity, diffusion, and nuclear reactions, capturing much of the quantifiable physics used in our code. For each isochrone, we construct simulated color–magnitude diagrams (CMDs) near the main-sequence turnoff region and apply two full-CMD-fitting methods to fit HST Advanced Camera for Surveys data across a range of distances and reddening and measure the absolute age of each GC from the resulting posterior distribution, which accounts for uncertainties in the stellar models, observations, and fitting method. The resulting best-fitting absolute ages range from ≈11.5 to 13.5 Gyr, with a typical error of 0.5–0.75 Gyr; the data show a clear trend toward older ages at lower metallicities. Notably, distance and reddening account for over 50% of the uncertainty in age determination in each case, with metallicity, α abundance, mixing length, and helium diffusion being the most important stellar physics parameters for the error budget. We also provide an absolute age–metallicity relation for Milky Way GCs.}, archive = {J_ApJ}, author = {Jiaqi (Martin) Ying and Brian Chaboyer and Michael Boylan-Kolchin and Daniel R. Weisz and Rowan Goebel-Bain}, doi = {10.3847/1538-4357/add471}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {52}, shortjournal = {The Astrophys. J.}, title = {The absolute age of milky way globular clusters}, volume = {987}, year = {2025}, }
• (2025). The impact of initial composition on massive star evolution and nucleosynthesis. ApJ, 987(1), 51. (www)

  @article{ , abstract = {We study the sensitivity of presupernova evolution and supernova nucleosynthesis yields of massive stars to variations of the initial composition. We use the solar abundances from Lodders, and compute two different sets of initial stellar compositions: (i) scaled solar abundances and (ii) the isotopic galactic chemical history model (GCH) developed by C. West & A. Heger. We run a grid of models using the KEPLER stellar evolution code, with 7 initial stellar masses, 12 initial metallicities, and the 2 scaling methods, to explore the effects on nucleosynthesis over a metallicity range of −4.0 ≤ [ Z ] ≤ +0.3. We find that the compositions from the GCH model better reproduce the weak s -process peak than the scaled solar models. The model yields are then used in the OMEGA Galactic Chemical Evolution (GCE) code to assess this result further. We find that initial abundances used in computing stellar structure have a larger impact on the GCE results than the initial abundances used in the large nuclear co-processing network, with the GCH model again being favored when compared to observations. Finally, a machine learning algorithm was used to verify the free parameter values of the GCH model, which were previously found by C. West & A. Heger using a stochastic fitting process. The updated model is provided as an accessible tool for further nucleosynthesis studies.}, archive = {J_ApJ}, author = {Christopher West and Alexander Heger and Benoit Côté and Lev Serxner and Haoxuan Sun}, doi = {10.3847/1538-4357/add68f}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {51}, shortjournal = {The Astrophys. J.}, title = {The impact of initial composition on massive star evolution and nucleosynthesis}, volume = {987}, year = {2025}, }
• (2025). Mapping galaxy images across ultraviolet, visible, and infrared bands using generative deep learning. ApJ, 987(1), 50. (www)

  @article{ , abstract = {We demonstrate that generative deep learning can translate galaxy observations across ultraviolet, visible, and infrared photometric bands. Leveraging mock observations from the Illustris simulations, we develop and validate a supervised image-to-image model capable of performing both band interpolation and extrapolation. The resulting trained models exhibit high fidelity in generating outputs, as verified by both general image comparison metrics (mean absolute error, SSIM, PSNR) and specialized astronomical metrics (Gini coefficient, M20). Moreover, we show that our models can be used to predict real-world observations, using data from the DECaLS survey as a case study. These findings highlight the potential of generative learning to augment astronomical data sets, enabling efficient exploration of multiband information in regions where observations are incomplete. This work opens new pathways for optimizing mission planning, guiding high-resolution follow-ups, and enhancing our understanding of galaxy morphology and evolution.}, archive = {J_ApJ}, author = {Youssef Zaazou and Alex Bihlo and Terrence S. Tricco}, doi = {10.3847/1538-4357/add695}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {50}, shortjournal = {The Astrophys. J.}, title = {Mapping galaxy images across ultraviolet, visible, and infrared bands using generative deep learning}, volume = {987}, year = {2025}, }
• (2025). Joint survey processing. III. compact oddballs in the COSMOS Field—Little red dots and transients. ApJ, 987(1), 49. (www)

  @article{ , abstract = {We present the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) G800L grism spectroscopy observation of the faint active galactic nuclei (AGN) candidates in the Cosmic Evolution Survey field at redshift of 6 selected by the point-source morphology and the photometry drop-off at 8000 Å. Among the sample of seven objects, only one is detected by multiple bands and has a similar shape of spectral energy distribution as the so-called “little red dots” of James Webb Space Telescope (JWST)–selected AGN candidates, but our object is 3 mag brighter than the JWST sample. We draw the upper limit of the AGN luminosity function Φ = 1.1 × 10 −7 Mpc 3 mag −1 for M UV = −21 at redshift of 6. The rest of the sample shows inconsistent flux density when comparing magnitudes of HST ACS F814W to the Subaru i -band and z -band magnitudes combined. The HST ACS G800L grism observation shows that this inconsistency cannot be created from an emission line. Therefore, we speculate that these objects are transients with the light-curve decay timescale of at most 6 yr in the observed frame.}, archive = {J_ApJ}, author = {Yu-Heng Lin and Andreas L. Faisst and Ranga-Ram Chary and Anton M. Koekemoer and Joseph Masiero and Daniel Masters and Vihang Mehta and Harry I. Teplitz and Gregory L. Walth and John R. Weaver}, doi = {10.3847/1538-4357/add7d9}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {49}, shortjournal = {The Astrophys. J.}, title = {Joint survey processing. III. compact oddballs in the COSMOS Field—Little red dots and transients}, volume = {987}, year = {2025}, }
• (2025). Iron-corrected single-epoch black hole masses of DESI quasars at low redshift. ApJ, 987(1), 48. (www)

  @article{ , abstract = {We present a study on the possible overestimation of single-epoch supermassive black hole (SMBH) masses in previous works, based on more than 55,000 type 1 quasars at 0.25 < z < 0.8 from the Dark Energy Spectroscopic Instrument (DESI). We confirm that iron emission strength serves as a good tracer of the Eddington ratio, and estimate SMBH masses using an iron-corrected R – L relation for H β , where R is the broad-line region size and L is the continuum luminosity. Compared with our measurements, previous canonical measurements without the iron correction are overestimated by a factor of 1.5 on average. The overestimation can be up to a factor of 5 for super-Eddington quasars. The fraction of super-Eddington quasars in our sample is about 5%, significantly higher than 0.4% derived from the canonical measurements. Using a sample featuring both H β and Mg ii emission lines, we calibrate Mg ii -based SMBH masses using iron-corrected, H β -based SMBH masses and establish an iron-corrected R – L relation for Mg ii . The revised relation features a flatter luminosity dependence with a slope of 0.36 and incorporates an additional term of −0.21 R Fe , where R Fe denotes the relative iron strength. We use this formula to build a catalog of about 0.5 million DESI quasars at 0.6 < z < 1.6. If these iron-corrected R – L relations for H β and Mg ii are valid at high redshift, current mass measurements of luminous quasars at z ≥ 6 would have been overestimated by a factor of 2.3 on average, alleviating the tension between SMBH mass and growth history in the early universe.}, archive = {J_ApJ}, author = {Zhiwei Pan and Linhua Jiang and Wei-Jian Guo and Shengxiu Sun and Małgorzata Siudek and Jessica Nicole Aguilar and Steven Ahlen and David Brooks and Todd Claybaugh and Axel de la Macorra and Peter Doel and Enrique Gaztañaga and Satya Gontcho A Gontcho and Stephanie Juneau and Theodore Kisner and Andrew Lambert and Martin Landriau and Laurent Le Guillou and Marc Manera and Paul Martini and Aaron Meisner and Ramon Miquel and John Moustakas and Adam Myers and Claire Poppett and Francisco Prada and Graziano Rossi and Eusebio Sanchez and Michael Schubnell and Hee-Jong Seo and David Sprayberry and Gregory Tarlé and Benjamin Alan Weaver and Hu Zou}, doi = {10.3847/1538-4357/add7dd}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {48}, shortjournal = {The Astrophys. J.}, title = {Iron-corrected single-epoch black hole masses of DESI quasars at low redshift}, volume = {987}, year = {2025}, }
• (2025). Blinded mock data challenge for gravitational-wave cosmology. i. assessing the robustness of methods using binary black hole mass spectrum. ApJ, 987(1), 47. (www)

  @article{ , abstract = {Gravitational wave sources are standard sirens that provide an independent way to map the cosmic expansion history by combining with an independent redshift measurement, either from an electromagnetic counterpart for a bright siren or using different statistical techniques for dark sirens. In this analysis, we perform the first Blinded Mock Data Challenge ( Blinded-MDC ) to test the robustness in inferring the value of Hubble constant H 0 for a dark siren technique which depends on astrophysical mass distribution of binary black holes (BBHs). We have considered different analysis setups for the Blinded-MDC to test both statistical and systematic uncertainties and demonstrate the capabilities in inferring H 0 with detector sensitivity as per the fourth observation run of LIGO-Virgo-KAGRA. We find that when the astrophysical population of BBHs matches with the underlying assumption of the model, a cosmological pipeline can recover the injected parameters using the observed mass distribution. However, when the mock mass distribution of the astrophysical population depends slightly on redshift and one is ignorant about it in analyzing the data, it can cause a systematic discrepancy in the inferred value of H 0 by about 1.5 σ , above the statistical fluctuations due to noise and a limited number of events. In the future, elaborate studies will be required to mitigate systematic uncertainties due to unknown astrophysical complexities. This MDC framework sets the road map for inspecting the precision and accuracy of standard siren cosmology and provides the first insight into the robustness of the population-dependent cosmology inference in a blinded analysis setup.}, archive = {J_ApJ}, author = {Aman Agarwal and Ulyana Dupletsa and Konstantin Leyde and Suvodip Mukherjee and Benot Revenu and Juan Esteban Rivera and Antonio Enea Romano and Mohit Raj Sah and Sergio Vallejo-Peña and Adrian Avendano and Freija Beirnaert and Gergely Dalya and Miguel Cifuentes Espitia and Christos Karathanasis and Santiago Moreno- Gonzalez and Lucas Quiceno and Federico Stachurski and Juan Garcia-Bellido and Rachel Gray and Nicola Tamanini and Cezary Turski}, doi = {10.3847/1538-4357/adda3a}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {47}, shortjournal = {The Astrophys. J.}, title = {Blinded mock data challenge for gravitational-wave cosmology. i. assessing the robustness of methods using binary black hole mass spectrum}, volume = {987}, year = {2025}, }
• (2025). Identifying compton-thick active galactic nuclei with a machine learning algorithm in chandra deep field-south. ApJ, 987(1), 46. (www)

  @article{ , abstract = {Compton-thick active galactic nuclei (CT-AGNs), which are defined by column density N H ≥ 1.5 × 10 24 cm −2 , emit feeble X-ray radiation, even undetectable by X-ray instruments. Despite this, the X-ray emissions from CT-AGNs are believed to be a substantial contributor to the cosmic X-ray background (CXB). According to synthesis models of AGNs, CT-AGNs are expected to make up a significant fraction of the AGN population, likely around 30% or more. However, only ∼11% of AGNs have been identified as CT-AGNs in the Chandra Deep Field-South (CDFS). To identify hitherto unknown CT-AGNs in the field, we used a random forest algorithm for identifying them. First, we build a secure classified subset of 210 AGNs to train and evaluate our algorithm. Our algorithm achieved an accuracy rate of 90% on the test set after training. Then, we applied our algorithm to an additional subset of 254 AGNs, successfully identifying 67 CT-AGNs within this group. This result significantly increased the fraction of CT-AGNs in the CDFS, which is closer to the theoretical predictions of the CXB. Finally, we compared the properties of host galaxies between CT-AGNs and non-CT-AGNs and found that the host galaxies of CT-AGNs exhibit higher levels of star formation activity.}, archive = {J_ApJ}, author = {Rui Zhang and Xiaotong Guo and Qiusheng Gu and Guanwen Fang and Jun Xu and Hai-Cheng Feng and Yongyun Chen and Rui Li and Nan Ding and Hongtao Wang}, doi = {10.3847/1538-4357/addaab}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {46}, shortjournal = {The Astrophys. J.}, title = {Identifying compton-thick active galactic nuclei with a machine learning algorithm in chandra deep field-south}, volume = {987}, year = {2025}, }
• (2025). Effects of environment on the size evolution of quiescent galaxies: Comparing galaxies in clusters and in the field at two rest-frame wavelengths. ApJ, 987(1), 45. (www)

  @article{ , abstract = {We investigate the impact of environment on quiescent galaxy (QG) size evolution using the CLAUDS+HSC imaging covering 18.6 deg 2 in five broad filters ( Ugriz ) and the effective radius of a single-Sérsic fit as a proxy for galaxy size. We estimate sizes in two rest-frame wavelengths—3000 Å (UV) and 5000 Å (optical)—for ∼86,000 massive ( M * ≤ 10 9.5 M ⊙ ) field QGs and for 1000 of their similarly massive counterparts from 47 clusters at 0.1 < z < 0.85. We fit the size–mass relation (SMR) for field and cluster QGs in five Δ z = 0.15 redshift bins and use the characteristic size of M * = 5 × 10 10 M ⊙ QGs (SMR’s zero-point) to trace the change in galaxy size over cosmic time and in two types of environment. Sizes of QGs are larger in the rest-frame UV than in the rest-frame optical in both clusters and the field, and this difference is more prominent in the field sample. However, QGs in clusters are systematically smaller than the field QGs, and this difference is significantly more pronounced if measured in the rest-frame UV light. Modeling of the redshift evolution in the characteristic QG size as R e ∝ (1 + z ) β shows that the cluster QGs ( β = −1.02 in UV and β = −1.00 in optical) grow in size as fast as the field QGs ( β = −0.95 in UV and −1.22 in optical). This fast growth of cluster QGs is consistent with size increase driven by the accretion of two subpopulations onto clusters: (a) field QGs that are larger than their quiescent counterparts in clusters, and (b) environmentally quenched galaxies (newcomers) that are larger than the rest of the quiescent population.}, archive = {J_ApJ}, author = {Angelo George and Ivana Damjanov and Marcin Sawicki and Devin J. Williams and Lingjian Chen and Guillaume Desprez and Marianna Annunziatella and Stéphane Arnouts and Stephen Gwyn and Danilo Marchesini and Thibaud Moutard and Anna Sajina}, doi = {10.3847/1538-4357/addc6b}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {45}, shortjournal = {The Astrophys. J.}, title = {Effects of environment on the size evolution of quiescent galaxies: Comparing galaxies in clusters and in the field at two rest-frame wavelengths}, volume = {987}, year = {2025}, }
• (2025). Interpreting the spectrotemporal properties of the black hole candidate swift j151857.0-572147 during its first outburst in 2024. ApJ, 987(1), 44. (www)

  @article{ , abstract = {The transient Galactic black hole candidate Swift J151857.0-572147 went through an outburst in 2024 March for the first time. Using publicly archived Insight-HXMT data, we have analyzed the timing and spectral properties of the source. We have extracted the properties of the quasiperiodic oscillations (QPOs) by fitting the power density spectrum, which inferred that the QPOs are of type C. We have detected QPOs up to ∼48 keV using an energy dependence study of the QPOs. A high-frequency QPO was not observed during this period. We also conclude that the oscillations of the shock in transonic advective accretion flows may be the possible reason for the origin of the QPOs. In the broad energy band of 2–100 keV, simultaneous data from the three onboard instruments of Insight-HXMT were used to perform spectral analysis. Different combinations of models, including a broken power law, a multicolor disk blackbody, interstellar absorption, nonrelativistic reflection in both neutral and ionized medium, and relativistic reflection, were used to understand the spectral properties during the outburst. We discovered that at the beginning of the analysis period, the source was in an intermediate state and later transitioning toward the soft state based on the spectral parameters. It has a high hydrogen column density, which could be due to some local absorption by the source.}, archive = {J_ApJ}, author = {Kaushik Chatterjee and S. Pujitha Suribhatla and Santanu Mondal and Chandra B. Singh}, doi = {10.3847/1538-4357/add699}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {44}, shortjournal = {The Astrophys. J.}, title = {Interpreting the spectrotemporal properties of the black hole candidate swift j151857.0-572147 during its first outburst in 2024}, volume = {987}, year = {2025}, }
• (2025). Frequency-dependent emission of the millisecond pulsar b1937+21 with the parkes ultrawideband receiver. ApJ, 987(1), 43. (www)

  @article{ , abstract = {In this study, we report on the broadband polarization behavior of the millisecond pulsar B1937+21 (J1939+2134), using high-quality observations made with the ultrawideband low receiver on Murriyang, the Parkes radio telescope. Observations spanning approximately 3 yr are carefully calibrated and integrated to produce high-signal-to-noise-ratio pulse profiles. Updated and accurate interstellar medium parameters toward the pulsar are obtained. The temporal variability of the dispersion measure, the Faraday rotation measure, and the flux density are analyzed from their corresponding structure functions. The frequency-and-longitude-dependent polarization evolutions are investigated. The spectra of the mean flux density follow a high-frequency cutoff power law, with the interpulse spectra being steeper than the main pulse. The fractional linear polarization of the main pulse decreases with increasing frequency, while the interpulse presents the opposite trend. Both the main pulse and interpulse exhibit increasing absolute circular polarization with increasing frequency. The peak intensity ratio of the main pulse to the interpulse increases with frequency, following a power-law spectrum with an index of 0.52 ± 0.02. The pulse width decreases with increasing frequency, further confirming that the emission height decreases with frequency, consistent with the results obtained from relativistic effects. These findings will contribute to a deeper understanding of the underlying emission mechanisms.}, archive = {J_ApJ}, author = {Z. Wang and Z. G. Wen and J. P. Yuan and N. Wang and W. Han and H. G. Wang and J. L. Chen}, doi = {10.3847/1538-4357/add728}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {43}, shortjournal = {The Astrophys. J.}, title = {Frequency-dependent emission of the millisecond pulsar b1937+21 with the parkes ultrawideband receiver}, volume = {987}, year = {2025}, }
• (2025). Alfvén wave mode conversion in neutron star magnetospheres: A semianalytic approach. ApJ, 987(1), 42. (www)

  @article{ , abstract = {We write down the force-free electrodynamics equations in dipole coordinates and solve for axisymmetric normal modes corresponding to Alfvénic perturbations in the magnetosphere of a neutron star. We show that a single Alfvén wave propagating on dipole field lines spontaneously sources a fast magnetosonic (fms) wave at the next order in the perturbation expansion, without needing three-wave interaction. The frequency of the sourced fms wave is twice the original Alfvén wave frequency, and the wave propagates spherically outward. The properties of the outgoing fms wave can be computed exactly using the usual devices of classical electrodynamics. We extend the calculation to the closed zone of a rotating neutron star magnetosphere, and show that the Alfvén wave also sources a spherical fms wave but at the same frequency as the primary Alfvén wave.}, archive = {J_ApJ}, author = {Alexander Y. Chen and Yajie Yuan and Dominic Bernardi}, doi = {10.3847/1538-4357/adda3b}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {42}, shortjournal = {The Astrophys. J.}, title = {Alfvén wave mode conversion in neutron star magnetospheres: A semianalytic approach}, volume = {987}, year = {2025}, }
• (2025). Scaler rates from the pierre auger observatory: A new proxy of solar activity. ApJ, 987(1), 41. (www)

  @article{ , abstract = {The modulation of low-energy galactic cosmic rays reflects interplanetary magnetic field variations and can provide useful information on solar activity. An array of ground-surface detectors can reveal the secondary particles, which originate from the interaction of cosmic rays with the atmosphere. In this work, we present an investigation of the low-threshold rate (scaler) time series recorded in 16 yr of operation by the Pierre Auger Observatory surface detectors in Malargüe, Argentina. Through an advanced spectral analysis, we detected highly statistically significant variations in the time series with periods ranging from the decadal to the daily scale. We investigate their origin, revealing a direct connection with solar variability. Thanks to their intrinsic very low noise level, the Auger scalers allow a thorough and detailed investigation of the galactic cosmic-ray flux variations in the heliosphere at different timescales and can, therefore, be considered a new proxy of solar variability.}, archive = {J_ApJ}, author = {The Pierre Auger Collaboration and A. Abdul Halim and P. Abreu and M. Aglietta and I. Allekotte and K. Almeida Cheminant and A. Almela and R. Aloisio and J. Alvarez-Muñiz and A. Ambrosone and J. Ammerman Yebra and G. A. Anastasi and L. Anchordoqui and B. Andrada and L. Andrade Dourado and S. Andringa and L. Apollonio and C. Aramo and E. Arnone and J. C. Arteaga Velázquez and P. Assis and G. Avila and E. Avocone and A. Bakalova and F. Barbato and A. Bartz Mocellin and J. A. Bellido and C. Berat and M. E. Bertaina and M. Bianciotto and P. L. Biermann and V. Binet and K. Bismark and T. Bister and J. Biteau and J. Blazek and J. Blümer and M. Boháčová and D. Boncioli and C. Bonifazi and L. Bonneau Arbeletche and N. Borodai and J. Brack and P. G. Brichetto Orchera and F. L. Briechle and A. Bueno and S. Buitink and M. Buscemi and M. Büsken and A. Bwembya and K. S. Caballero-Mora and S. Cabana-Freire and L. Caccianiga and F. Campuzano and J. Caraça-Valente and R. Caruso and A. Castellina and F. Catalani and G. Cataldi and L. Cazon and M. Cerda and B. Čermáková and A. Cermenati and J. A. Chinellato and J. Chudoba and L. Chytka and R. W. Clay and A. C. Cobos Cerutti and R. Colalillo and R. Conceição and A. Condorelli and G. Consolati and M. Conte and F. Convenga and D. Correia dos Santos and P. J. Costa and C. E. Covault and M. Cristinziani and C. S. Cruz Sanchez and S. Dasso and K. Daumiller and B. R. Dawson and R. M. de Almeida and E.-T. de Boone and B. de Errico and J. de Jesús and S.J. de Jong and J. R. T. de Mello Neto and I. De Mitri and J. de Oliveira and D. de Oliveira Franco and F. de Palma and V. de Souza and E. De Vito and A. Del Popolo and O. Deligny and N. Denner and L. Deval and A. di Matteo and C. Dobrigkeit and J. C. D’Olivo and L. M. Domingues Mendes and Q. Dorosti and J. C. dos Anjos and R. C. dos Anjos and J. Ebr and F. Ellwanger and M. Emam and R. Engel and I. Epicoco and M. Erdmann and A. Etchegoyen and C. Evoli and H. Falcke and G. Farrar and A. C. Fauth and T. Fehler and F. Feldbusch and A. Fernandes and B. Fick and J. M. Figueira and P. Filip and A. Filipčič and T. Fitoussi and B. Flaggs and T. Fodran and M. Freitas and T. Fujii and A. Fuster and C. Galea and B. García and C. Gaudu and P. L. Ghia and U. Giaccari and F. Gobbi and F. Gollan and G. Golup and M. Gómez Berisso and P. F. Gómez Vitale and J. P. Gongora and J. M. González and N. González and D. Góra and A. Gorgi and M. Gottowik and F. Guarino and G. P. Guedes and E. Guido and L. Gülzow and S. Hahn and P. Hamal and M. R. Hampel and P. Hansen and V. M. Harvey and A. Haungs and T. Hebbeker and C. Hojvat and J. R. Hörandel and P. Horvath and M. Hrabovský and T. Huege and A. Insolia and P. G. Isar and P. Janecek and V. Jilek and K.-H. Kampert and B. Keilhauer and A. Khakurdikar and V. V. Kizakke Covilakam and H. O. Klages and M. Kleifges and J. Köhler and F. Krieger and M. Kubatova and N. Kunka and B. L. Lago and N. Langner and M. A. Leigui de Oliveira and Y. Lema-Capeans and A. Letessier-Selvon and I. Lhenry-Yvon and L. Lopes and J. P. Lundquist and A. Machado Payeras and M. Mallamaci and D. Mandat and B. C. Manning and P. Mantsch and F. M. Mariani and A. G. Mariazzi and I. C. Mariş and G. Marsella and D. Martello and S. Martinelli and M. A. Martins and H.-J. Mathes and J. Matthews and G. Matthiae and E. Mayotte and S. Mayotte and P. O. Mazur and G. Medina-Tanco and J. Meinert and D. Melo and A. Menshikov and C. Merx and S. Michal and M. I. Micheletti and L. Miramonti and M. Mogarkar and S. Mollerach and F. Montanet and L. Morejon and K. Mulrey and R. Mussa and W. M. Namasaka and S. Negi and L. Nellen and K. Nguyen and G. Nicora and M. Niechciol and D. Nitz and D. Nosek and A. Novikov and V. Novotny and L. Nožka and A. Nucita and L. A. Núñez and J. Ochoa and C. Oliveira and L. Östman and M. Palatka and J. Pallotta and S. Panja and G. Parente and T. Paulsen and J. Pawlowsky and M. Pech and J. Pȩkala and R. Pelayo and V. Pelgrims and L. A. S. Pereira and E. E. Pereira Martins and C. Pérez Bertolli and L. Perrone and S. Petrera and C. Petrucci and T. Pierog and M. Pimenta and M. Platino and B. Pont and M. Pourmohammad Shahvar and P. Privitera and M. Prouza and K. Pytel and S. Querchfeld and J. Rautenberg and D. Ravignani and J. V. Reginatto Akim and A. Reuzki and J. Ridky and F. Riehn and M. Risse and V. Rizi and E. Rodriguez and G. Rodriguez Fernandez and J. Rodriguez Rojo and M. J. Roncoroni and S. Rossoni and M. Roth and E. Roulet and A.C. Rovero and A. Saftoiu and M. Saharan and F. Salamida and H. Salazar and G. Salina and P. Sampathkumar and N. San Martin and J. D. Sanabria Gomez and F. Sánchez and E. M. Santos and E. Santos and F. Sarazin and R. Sarmento and R. Sato and P. Savina and V. Scherini and H. Schieler and M. Schimassek and M. Schimp and D. Schmidt and O. Scholten and H. Schoorlemmer and P. Schovánek and F. G. Schröder and J. Schulte and T. Schulz and S. J. Sciutto and M. Scornavacche and A. Sedoski and A. Segreto and S. Sehgal and S. U. Shivashankara and G. Sigl and K. Simkova and F. Simon and R. Šmída and P. Sommers and R. Squartini and M. Stadelmaier and S. Stanič and J. Stasielak and P. Stassi and S. Strähnz and M. Straub and T. Suomijärvi and A. D. Supanitsky and Z. Svozilikova and Z. Szadkowski and F. Tairli and A. Tapia and C. Taricco and C. Timmermans and O. Tkachenko and P. Tobiska and C. J. Todero Peixoto and B. Tomé and A. Travaini and P. Travnicek and M. Tueros and M. Unger and R. Uzeiroska and L. Vaclavek and M. Vacula and I. Vaiman and J. F. Valdés Galicia and L. Valore and E. Varela and V. Vašíčková and A. Vásquez-Ramírez and D. Veberič and I. D. Vergara Quispe and S. Verpoest and V. Verzi and J. Vicha and J. Vink and S. Vorobiov and J. B. Vuta and C. Watanabe and A. A. Watson and A. Weindl and M. Weitz and L. Wiencke and H. Wilczyński and D. Wittkowski and B. Wundheiler and B. Yue and A. Yushkov and E. Zas and D. Zavrtanik and M. Zavrtanik and I. Bizzarri and C. Dionese and S. Mancuso}, doi = {10.3847/1538-4357/adccc3}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {41}, shortjournal = {The Astrophys. J.}, title = {Scaler rates from the pierre auger observatory: A new proxy of solar activity}, volume = {987}, year = {2025}, }
• (2025). Tracing high-z galaxies in X-rays with JWST and chandra. ApJ, 987(1), 40. (www)

  @article{ , abstract = {We leverage James Webb Space Telescope (JWST) data from the COSMOS-Web survey in order to provide updated measurements on the auto-power spectrum of the now resolved cosmic near-infrared background (CIB) and its coherence with the unresolved soft cosmic X-ray background (CXB) observed by Chandra at z > 6. Maps of the CIB in the F277W and F444W NIRCam filters are constructed with sources fainter than m AB = 25 and cross-correlated with the CXB in the [0.5–2] keV band. We find that on scales between 1″ and 1000″ the CIB–CXB cross-power in both NIRCam filters is statistically significant, with signal-to-noise ratios (S/Ns) of 4.80 and 6.20, respectively, from redshifts 0 ≤ z ≤ 13. In our high- z (6 ≤ z ≤ 13) interval we find coherence in both filters, with S/Ns of 7.32 and 5.39, respectively. These results suggest that there are X-ray-emitting galaxies resolved by JWST, including star-forming galaxies and active galactic nuclei. We fit the large-scale biasing of the IR sources producing the CIB as a function of z with results consistent with prior measurements, and place constraints on the CXB flux and biasing at low and high z . The CXB flux measurements presented in this study suggest that approximately 94% of the [0.5–2] keV CXB is resolved, and this value is consistent within 2 σ with the complete resolution of the [0.5–2] keV CXB.}, archive = {J_ApJ}, author = {Aidan J. Kaminsky and Nico Cappelluti and Günther Hasinger and Alessandro Peca and Caitlin M. Casey and Giulia Cerini and Nicole E. Drakos and Andreas Faisst and Ghassem Gozaliasl and Olivier Ilbert and Jeyhan S. Kartaltepe and Alexander Kashlinsky and Anton M. Koekemoer and Henry Joy McCracken and Jason Rhodes and Brant E. Robertson and Marko Shuntov and Joseph Sterling}, doi = {10.3847/1538-4357/adcede}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {40}, shortjournal = {The Astrophys. J.}, title = {Tracing high-z galaxies in X-rays with JWST and chandra}, volume = {987}, year = {2025}, }
• (2025). P-CORONA: A new tool for calculating the intensity and polarization of coronal lines in 3D models of the solar corona. ApJ, 987(1), 39. (www)

  @article{ , abstract = {The critical need to study the magnetic field in the solar corona is highlighted by recent observational facilities, such as the Daniel K. Inouye Solar Telescope and Aditya-L1. A powerful tool for probing the magnetism of the solar corona is forward modeling of the intensity and polarization of coronal emission lines in three-dimensional (3D) magnetohydrodynamic models. Here we present P-CORONA, a new spectral synthesis code designed to calculate the intensity and polarization of coronal lines in 3D models of the solar corona, taking into account the symmetry breaking induced by magnetic and velocity fields. P-CORONA allows the calculation of the on-disk and off-limb intensity and polarization of forbidden and permitted coronal lines, thus facilitating a wide range of investigations. Applying the quantum theory of atom–photon interactions, P-CORONA accounts for the spectral line polarization caused by anisotropic radiation pumping and the Hanle and Zeeman effects, making it a valuable tool for investigating coronal magnetic fields. This paper details the code’s theoretical formulation, implementation, and illustrative results of calculations in different 3D coronal models (MURaM and Predictive Science Inc.), including the impact of the Zeeman effect from the transverse magnetic field component on selected coronal forbidden lines. P-CORONA is now accessible to the research community on GitLab and Zenodo, providing a resource to facilitate research aimed at advancing our understanding of coronal magnetism and dynamics.}, archive = {J_ApJ}, author = {Supriya Hebbur Dayananda and Ángel de Vicente and Tanausú del Pino Alemán and Javier Trujillo Bueno and Nataliia G. Shchukina}, doi = {10.3847/1538-4357/add32e}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {39}, shortjournal = {The Astrophys. J.}, title = {P-CORONA: A new tool for calculating the intensity and polarization of coronal lines in 3D models of the solar corona}, volume = {987}, year = {2025}, }
• (2025). A new formation mechanism of counterstreaming mass flows in filaments and the doppler bullseye pattern in prominences. ApJ, 987(1), 38. (www)

  @article{ , abstract = {The eruption of a solar prominence can eject substantial mass and magnetic field into interplanetary space and cause geomagnetic storms. However, various questions about prominences and their eruption mechanism remain unclear. In particular, what causes the intriguing Doppler bullseye pattern in prominences has not yet been solved, despite some preliminary studies proposing that they are probably associated with counterstreaming mass flows. Previous studies are mainly based on single-angle and short-timescale observations, making it difficult to determine the physical origin of Doppler bullseye patterns in prominences. Here, taking advantage of stereoscopic observations taken by the Solar Dynamics Observatory and the Solar Terrestrial Relations Observatory and a three-dimensional numerical simulation, we investigate the origin of the prominence Doppler bullseye pattern by tracing a long-lived transequatorial filament/prominence from 2012 July 23 to August 4. We find that the Doppler bullseye pattern can be launched by repeated coronal jets at one end of the prominence. It is evidenced in our observations and simulation that during the forward traveling of jet plasma along the helical magnetic field structure of the prominence, part of the ejecting plasma can not pass through the apex of the prominence due to the insufficient kinetic energy and therefore forms a backward-moving mass flow along the same or neighboring magnetic field lines. This process finally forms counterstreaming mass flows in on-disk filaments. When the on-disk filament rotates to the solar limb to be a prominence, the counterstreaming mass flows are naturally observed as a Doppler bullseye pattern.}, archive = {J_ApJ}, author = {Chengrui Zhou and Yuandeng Shen and Chun Xia and Dongxu Liu and Zehao Tang and Surui Yao}, doi = {10.3847/1538-4357/add32f}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {38}, shortjournal = {The Astrophys. J.}, title = {A new formation mechanism of counterstreaming mass flows in filaments and the doppler bullseye pattern in prominences}, volume = {987}, year = {2025}, }
• (2025). The 2023 outburst of the gaia alerted EXor gaia23bab. ApJ, 987(1), 37. (www)

  @article{ , abstract = {Episodic accretion is a fundamental process in the build-up of the stellar mass. EX Lupi-type eruptive young stars (EXors) represent one of the main types of episodic accretion. We study the recently discovered EXor Gaia23bab during its 2023 outburst. We obtained optical and near-infrared photometry and spectroscopy to probe the variation of the physical properties of Gaia23bab during its recent outburst. We also collected archival photometry to study a previous outburst of the star. We used several accretion tracers, including the Ca ii triplet, He i , and various hydrogen lines from the Paschen and Brackett series, to measure the accretion rate during the outburst. The accretion rate is consistent with ∼2.0 × 10 −7 M ⊙ yr −1 . Comparing the line fluxes of the hydrogen Brackett series to predictions of Case B theory suggests excitation temperatures of 5000–10,000 K and electron densities of 10 9 –10 10 cm −3 . Comparison to the predictions of a model for T Tauri stars revealed that the fluxes of the Balmer series are consistent with temperatures of 5000–12,500 K and a hydrogen density of 10 8 cm −3 , while the fluxes of the Paschen series are consistent with temperatures in the range between 10,000 and 12,500 K and a hydrogen density of 10 11 cm −3 . The derived temperatures and densities confirm that Gaia23bab is a prototypical EXor, not only due to its accretion rate, but also based on the best-fit temperatures and densities revealed by the detected hydrogen lines.}, archive = {J_ApJ}, author = {Zsófia Nagy and Ágnes Kóspál and Péter Ábrahám and Teresa Giannini and Mária Kun and Manuele Gangi and Fernando Cruz-Sáenz de Miera and Michael Kuhn and Michał Siwak and Máté Szilágyi and Eleonora Fiorellino and Simone Antoniucci and Katia Biazzo and Attila Bódi and Zsófia Bora and Borbála Cseh and Marek Dróżdż and Ágoston Horti-Dávid and András Péter Joó and Csilla Kalup and Krzysztof Kotysz and Levente Kriskovics and Gábor Marton and Przemysław J. Mikołajczyk and Brunella Nisini and András Pál and Bálint Seli and Ádám Sódor and László Szabados and Norton Olivér Szabó and Zsófia Marianna Szabó and Róbert Szakáts and Vázsony Varga and József Vinkó and Łukasz Wyrzykowski and Paweł Zieliński}, doi = {10.3847/1538-4357/add68e}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {37}, shortjournal = {The Astrophys. J.}, title = {The 2023 outburst of the gaia alerted EXor gaia23bab}, volume = {987}, year = {2025}, }
• (2025). Comprehensive laboratory benchmark of K-shell dielectronic satellites of fe xxv–xxi ions. ApJ, 987(1), 36. (www)

  @article{ , abstract = {We report on comprehensive laboratory studies of the K-shell dielectronic recombination resonances of Fe xxv – xxi ions that prominently contribute to the hard X-ray spectrum of hot astrophysical plasmas. By scanning a monoenergetic electron beam to resonantly excite trapped Fe ions in an electron beam ion trap and achieving a high electron–ion collision energy resolution of ∼7 eV, we resolve their respective KL n satellites up to {n}^{{\prime} }=11 . By normalization to known radiative recombination cross sections, we also determine their excitation cross sections and that of the continuum with uncertainties below 15% and verify our results with an independent normalization based on previous measurements. Our experimental data excellently confirm the accuracy and suitability of distorted-wave calculations obtained with the Flexible Atomic Code for modeling astrophysical and fusion plasmas.}, archive = {J_ApJ}, author = {Chintan Shah and Pedro Amaro and Filipe Grilo and Ming Feng Gu and Liyi Gu and José Paulo Santos and F. Scott Porter and Thomas Pfeifer and Maurice A. Leutenegger and José R. Crespo López-Urrutia}, doi = {10.3847/1538-4357/addaba}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {36}, shortjournal = {The Astrophys. J.}, title = {Comprehensive laboratory benchmark of K-shell dielectronic satellites of fe xxv–xxi ions}, volume = {987}, year = {2025}, }
• (2025). Nonlinear coupling between magnetar QPOs. ApJ, 987(1), 35. (www)

  @article{ , abstract = {The quasiperiodic oscillations (QPOs) observed in the tails of magnetar giant γ -ray flares have long been interpreted as normal oscillation modes of these stars. However, most studies modeling QPOs have neglected some key features in the analyses of the signals, namely that QPOs appear to be detectable only intermittently and exhibit drifts in their frequencies. These are typical characteristics of nonlinear mode coupling, where, at leading order, the modes couple and evolve collectively as triplets. Using a representative triplet of modes, we solve the system’s nonlinear equations of motion analytically and argue that the coupling is likely axial-axial-polar in nature, with the observed intermittence and frequency drifts providing a way to infer details of the magnetar’s internal magnetic field geometry.}, archive = {J_ApJ}, author = {P. Pnigouras and S.K. Lander}, doi = {10.3847/1538-4357/adceee}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {35}, shortjournal = {The Astrophys. J.}, title = {Nonlinear coupling between magnetar QPOs}, volume = {987}, year = {2025}, }
• (2025). Pulse profiles of accreting neutron stars from GRMHD simulations. ApJ, 987(1), 34. (www)

  @article{ , abstract = {The pulsed X-ray emission from the neutron star surface acts as a window to study the state of matter in the neutron star interior. For accreting millisecond pulsars, the surface X-ray emission is generated from the “hotspots” formed due to the magnetically channeled accretion flow hitting the stellar surface. The emission from these hotspots is modulated by stellar rotation, giving rise to pulsations. Using global three-dimensional general relativistic magnetohydrodynamic (GRMHD) simulations of the star-disk system, we investigate the accretion hotspots and the corresponding X-ray pulse properties of accreting millisecond pulsars with dipolar magnetic fields. The accretion spot morphologies in our simulations are entirely determined by the accretion columns and vary as a function of the stellar magnetic inclination. For lower magnetic inclinations, the hotspots are shaped like crescents around the magnetic axis and are transformed into elongated bars for higher inclinations. We model the X-ray pulses resulting from the simulated hotspots using general-relativistic ray-tracing calculations and quantify the variability of the pulsed signal. The pulse amplitudes in our simulations usually range between 1% and 12% rms and are consistent with the observed values. We find that the turbulent accretion flow in the GRMHD simulations introduces significant broadband variability on a timescale similar to the stellar rotational period. We also explore the impact of electron scattering absorption and show that, along with being a key factor in determining the pulse characteristics, this also introduces significant additional variability and higher harmonics in the bolometric light curve of the accreting sources.}, archive = {J_ApJ}, author = {Pushpita Das and Tuomo Salmi and Jordy Davelaar and Oliver Porth and Anna Watts}, doi = {10.3847/1538-4357/add472}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {34}, shortjournal = {The Astrophys. J.}, title = {Pulse profiles of accreting neutron stars from GRMHD simulations}, volume = {987}, year = {2025}, }
• (2025). GULP. II. hierarchical distribution and evolution of young stellar structures in NGC 4449. ApJ, 987(1), 33. (www)

  @article{ , abstract = {We investigate the hierarchical distribution and evolution of young stellar structures in the dwarf starburst galaxy NGC 4449 using data from the GULP survey. By analyzing the spatial distribution of field stars younger than 100 Myr, we identify large-scale stellar complexes and substructures using HDBSCAN—a density-based clustering algorithm—and trace their evolution over time. While comparing these stellar structures in different regions of the galaxy, we find that the central bar-like region shows a clear expansion of the structures within the first ∼60 Myr, while the arm-like structure in the northeast shows no discernible trend, possibly due to external perturbations from tidal interactions with a neighboring galaxy. An age-dependent two-point correlation function (TPCF) analysis shows that young stars exhibit a strong hierarchical distribution, with clustering strength decreasing over time. The power-law slope of the TPCF, which starts at α ∼ 0.65 for stars younger than 5 Myr, shows a slight decline to α ∼ 0.4 for stars older than 50 Myr, though it does not reach a completely flat (random) distribution. This trend indicates a subtle weakening of structural hierarchy among young (<100 Myr) stars, which is primarily driven by internal stellar motions. Future work will extend this analysis to the remaining 26 galaxies in the GULP survey to better constrain the role of the galactic environment in shaping the hierarchical evolution of young stellar populations.}, archive = {J_ApJ}, author = {Beena Meena and Elena Sabbi and Peter Zeidler and Bruce G. Elmegreen and Jan J. Eldridge and Varun Bajaj and Mario Gennaro and Anna Pasquali and Debra M. Elmegreen and Ralf S. Klessen and Linda J. Smith and Luciana Bianchi and Aida Wofford and Pietro Facchini and John S. Gallagher and Daniela Calzetti and Eva K. Grebel and Angela Adamo and (GULP)}, doi = {10.3847/1538-4357/add475}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {33}, shortjournal = {The Astrophys. J.}, title = {GULP. II. hierarchical distribution and evolution of young stellar structures in NGC 4449}, volume = {987}, year = {2025}, }
• (2025). Investigating the possible contribution of helicity condensation to the ambient increase in solar open flux. ApJ, 987(1), 32. (www)

  @article{ , abstract = {The Sun’s Open Flux plays a vital role in heliospheric physics and for the origin of the solar wind. A key problem faced by global magnetic field models of the solar corona is that they consistently underestimate the amount of Open Flux compared to in situ measurements. The purpose of the present paper is to consider if statistically averaged helicity condensation (SAHC) can reduce this discrepancy by increasing the simulated Open Flux found in potential field source surface (PFSS) models. We consider each Carrington rotation from 1646–2149 (1976 September to 2014 April). For each rotation, we hold the photosphere fixed, construct a PFSS model, and inject nonpotentiality into the coronal field by applying SAHC at different angular rotation rates, ω . When ω exceeds 2.5 × 10 −6 s −1 , both ambient and sporadic enhancements of Open Flux are found within the Carrington rotation timescale. As ω increases, the amount of ambient Open Flux increases, along with the frequency of sporadic events. These enhancements are accompanied by increased footpoint area of open field lines, where the open field locations at each pole expand by up to 3 ∘ –6 ∘ of latitude. A solar cycle dependence is found with higher increases in ambient Open Flux at solar maximum compared to solar minimum. Comparing our results with 27 day averaged OMNI spacecraft measurements, our highest value of ω = 10 × 10 −6 s −1 can resolve just under 50% of the discrepancy between in situ Open Flux measurements and PFSS models. Although helicity condensation cannot fully resolve the discrepancy, it can significantly contribute toward reducing it.}, archive = {J_ApJ}, author = {Jonah J. Klowss and Duncan H. Mackay}, doi = {10.3847/1538-4357/add533}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {32}, shortjournal = {The Astrophys. J.}, title = {Investigating the possible contribution of helicity condensation to the ambient increase in solar open flux}, volume = {987}, year = {2025}, }
• (2025). Large-amplitude whistler precursors and >MeV particles observed at a weak interplanetary shock by parker solar probe. ApJ, 987(1), 31. (www)

  @article{ , abstract = {We report observations of an interplanetary (IP) shock observed by Parker Solar Probe (PSP) on 2024 September 29 at ∼07:50:29 UTC. PSP was only ∼17.07 R s from the Sun, making this one of the closest observed IP shocks to date. The IP shock was a weak ( M f ∼ 1.2), quasi-perpendicular ( θ Bn ∼ 50°), and of moderate speed ( V shn ∼ 465 km s −1 ). The standard shock acceleration mechanisms (e.g., Fermi acceleration) predict that such an unremarkable shock cannot generate energetic particles (i.e., over 4 orders of magnitude above thermal energies), which is supported by decades of IP shock observations near 1 au. However, ∼MeV energy protons with an inverse velocity arrival and synchrotron radiation (due to ∼MeV energy electrons) were observed upstream. This raised the question of what was different about this shock. One observation was that of a fast/magnetosonic-whistler precursor with peak-to-peak magnetic field amplitudes >700 nT, electric fields >2000 mV m −1 , and Poynting fluxes >230 mW m −2 . These are 2 orders of magnitude larger than any previously observed whistler precursor. To put the amplitudes in context, the lower bound Poynting flux estimates are >200 times what is necessary to drive the terrestrial aurora. Note that the normalized wave parameters (e.g., frequency) were found to be consistent with previous studies near 1 au. Thus, the precursors cannot likely generate a larger fraction of energetic particles than similar precursors near 1 au. However, the much larger amplitudes would allow for higher maximum energies. This raises important questions about inaccessible shocks in more extreme astrophysical environments and what potential energization they may have in light of these observations.}, archive = {J_ApJ}, author = {Lynn B. Wilson and J. Grant Mitchell and Adam Szabo and Immanuel C. Jebaraj and Michael L. Stevens and David M. Malaspina and Grant D. Berland and Athanasios Kouloumvakos and Stuart D. Bale and Roberto Livi and Jasper S. Halekas and Christina M. S. Cohen}, doi = {10.3847/1538-4357/add6a8}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {31}, shortjournal = {The Astrophys. J.}, title = {Large-amplitude whistler precursors and >MeV particles observed at a weak interplanetary shock by parker solar probe}, volume = {987}, year = {2025}, }
• (2025). Three-dimensional orbital architectures and detectability of adjacent companions to hot jupiters. ApJ, 987(1), 30. (www)

  @article{ , abstract = {The orbital properties of the (as yet) small population of hot Jupiters with nearby planetary companions provide valuable constraints on the past migration processes of these systems. In this work, we explore the likelihood that dynamical perturbations could cause nearby inner or outer companions to a hot Jupiter to leave the transiting plane, potentially leaving these companions undetected despite their presence at formation. Using a combination of analytical and numerical models, we examine the effects of stellar evolution on hot Jupiter systems with nearby companions and identify several possible outcomes. We find that while inner companions are generally unlikely to leave the transiting plane, outer companions are more prone to decoupling from the hot Jupiter and becoming nontransiting, depending on the system’s initial orbital architecture. Additionally, we observe a range of dynamical behaviors, including overall stability, inclination excitation, and, in some cases, instability leading to the ejection or collision of planets. We also show that the effect of stellar obliquity (with respect to the mean planet of the planets) is to amplify these effects and potentially cause outer companions to attain nonmutually transiting configurations more often. Our results highlight the complex dynamical pathways shaping the architectures of hot Jupiter systems.}, archive = {J_ApJ}, author = {Thomas MacLean and Juliette Becker}, doi = {10.3847/1538-4357/add884}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {30}, shortjournal = {The Astrophys. J.}, title = {Three-dimensional orbital architectures and detectability of adjacent companions to hot jupiters}, volume = {987}, year = {2025}, }
• (2025). Oort cloud formation and evolution in star clusters. ApJ, 987(1), 29. (www)

  @article{ , abstract = {It is unknown whether an Oort cloud reaches its maximum mass within its star’s birth cluster or millions of years later. Complicating the Oort cloud evolution process is the fact that comets can be stripped from orbit due to perturbations from passing stars. We explore how a star’s cluster escape time ( t esc ) and the time its Oort cloud reaches maximum mass ( t {}_{{\rm{\max }}} ) affect the Oort cloud’s ability to survive via N -body simulations. In a 14 M ⊙ pc –3 cluster, we identify 50 stars of 1 M ⊙ with a range of t esc to host Oort clouds, each with 1000 comets at t {}_{{\rm{\max }}} . For each host, we consider Oort clouds that reach maximum mass 0, 50, and 250 Myr after the cluster’s formation. Each Oort cloud’s evolution is simulated in the cluster from t {}_{{\rm{\max }}} to t esc . Only a fraction of comets tend to remain in orbit, with this amount depending on t {}_{{\rm{\max }}} and t esc . We observe that 12%, 22%, and 32% of Oort clouds with a t {}_{{\rm{\max }}} of 0, 50, and 250 Myr retain >50% of their comets at t esc , respectively. We find that the fraction of comets stripped has the relationship f=m\,{{\rm{log}}}_{10}\left(\frac{{t}_{{\rm{esc}}}-{t}_{max}}{{\rm{Myr}}}\right) , where m = 0.32 ± 0.04, indicating that the longer the Oort cloud remains in the cluster, the more comets are stripped, with this fraction increasing logarithmically at approximately the same rate for each t {}_{{\rm{\max }}} .}, archive = {J_ApJ}, author = {Justine C. Obidowski and Jeremy J. Webb and Simon Portegies Zwart and Maxwell X. Cai}, doi = {10.3847/1538-4357/add92c}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {29}, shortjournal = {The Astrophys. J.}, title = {Oort cloud formation and evolution in star clusters}, volume = {987}, year = {2025}, }
• (2025). Debiasing structure function estimates from sparse time series of the solar wind: A data-driven approach. ApJ, 987(1), 28. (www)

  @article{ , abstract = {Structure functions (SFs), which quantify the moments of increments of a stochastic process, are essential complementary statistics to power spectra for analyzing the self-similar behavior of a time series. However, many real-world data sets, such as those from spacecraft monitoring the solar wind, contain gaps, which inevitably corrupt the statistics. The nature of this corruption for SFs remains poorly understood—indeed, often overlooked. In this study, we simulate gaps in a large set of Parker Solar Probe magnetic field intervals to characterize how missing data affect SFs of solar wind turbulence. We find that linear interpolation systematically underestimates the true SF, and we introduce a simple, empirically derived correction factor to address this bias. Learned from data from a single spacecraft, the correction generalizes well to solar wind measured elsewhere in the heliosphere. Compared to conventional gap-handling methods, our approach reduces the mean error for missing data fractions above 20%, and the overall error is reduced by nearly 50% when averaged across all missing fractions tested. We apply the correction to Voyager intervals from the inner heliosheath and local interstellar medium (60%–85% missing) and recover spectral indices consistent with previous studies. The correction factor is released as an open-source Python package, enabling more accurate analysis of scaling in gapped solar wind data sets.}, archive = {J_ApJ}, author = {Daniel Wrench and Tulasi N. Parashar}, doi = {10.3847/1538-4357/addc6a}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {28}, shortjournal = {The Astrophys. J.}, title = {Debiasing structure function estimates from sparse time series of the solar wind: A data-driven approach}, volume = {987}, year = {2025}, }
• (2025). Continuous habitable zone metric for prioritizing habitable worlds observatory targets. ApJ, 987(1), 27. (www)

  @article{ , abstract = {Future direct imaging space telescopes, such as NASA’s Habitable Worlds Observatory (HWO), will be the first capable of both detecting and characterizing terrestrial exoplanets in the habitable zones (HZs) of nearby Sun-like stars. Since this will require a significant amount of time and resources for even a single system or exoplanet, the likelihood that a system will host detectable life should be considered when prioritizing observations. One method of prioritization is to estimate the likelihood that an exoplanet has remained continuously within the HZ long enough for life to emerge and make a detectable impact on the atmosphere. We utilize a Bayesian method to calculate the likelihood that a given orbital radius around a star is currently in the 2 Gyr continuous habitable zone (CHZ 2 ), the approximate time it took life on Earth to significantly oxygenate the atmosphere. We apply this method to the 164 stars in the NASA Exoplanet Exploration Program Mission Star List for HWO, representing a preliminary sample of Sun-like stars with HZs most accessible to a future direct imaging mission. By considering the CHZ 2 likelihood at all orbital radii outside a hypothetical inner working angle for HWO, we define a metric for prioritizing targets according to the accessibility and total extent of the CHZ 2 . We find that the CHZ 2 metric peaks between 3 and 4 Gyr for late F and early G dwarfs, but tentatively determine that stars earlier than ∼F3 or hotter than ∼6600 K are unlikely to have a CHZ 2 at the time of observation.}, archive = {J_ApJ}, author = {Austin Ware and Patrick Young}, doi = {10.3847/1538-4357/adddbb}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {27}, shortjournal = {The Astrophys. J.}, title = {Continuous habitable zone metric for prioritizing habitable worlds observatory targets}, volume = {987}, year = {2025}, }
• (2025). Exploring compact symmetric objects with complex morphologies. ApJ, 987(1), 26. (www)

  @article{ , abstract = {Compact symmetric objects (CSOs) are a unique class of jetted active galactic nuclei defined by subkiloparsec radio emission, showing radio structure on both sides of the central engine. CSOs tend to exhibit little to no relativistic beaming, thereby allowing us to determine their physical characteristics, such as the magnetic field strength and particle energy density. Selected with a literature search, we describe very long baseline interferometry observations, imaging, and analyses of 167 CSO candidates. We identified 65 new bona fide CSOs, thus almost doubling the number of known bona fide CSOs to 144. With our greater breadth of sources, we confirm that edge-dimmed CSOs (CSO-1s) may represent a more diverse population than originally expected. We highlight a number of CSOs with complex morphologies, including candidates for supermassive binary black holes and CSOs that appear to have morphologies akin to wide-angle tail galaxies, which could perhaps indicate that some CSOs are experiencing a galactic merger.}, archive = {J_ApJ}, author = {E. E. Sheldahl and G. B. Taylor and S. E. Tremblay and W. Peters and S. Kiehlmann and R. D. Blandford and M. L. Lister and T. J. Pearson and A. C. S. Readhead and F. Schinzel and A. Siemiginowska and R. Skalidis}, doi = {10.3847/1538-4357/adcc28}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {26}, shortjournal = {The Astrophys. J.}, title = {Exploring compact symmetric objects with complex morphologies}, volume = {987}, year = {2025}, }
• (2025). Investigating silicate, carbon, and water in the diffuse interstellar medium: The first shots from WISCI. ApJ, 987(1), 25. (www)

  @article{ , abstract = {The dusty interstellar medium (ISM) of the Milky Way is distributed in a complex, cloudy structure. It is fundamental to the radiation balance within the Milky Way, provides a reaction surface to form complex molecules, and is the feedstock for future generations of stars and planets. The life cycle of interstellar dust is not completely understood, and neither are its structure nor composition. The abundance, composition, and structure of dust in the diffuse ISM can be determined by combining infrared, optical, and ultraviolet spectroscopy. JWST enables measurement of the faint absorption of ISM dust grains against bright stars at kiloparsec distances across the infrared spectrum. Here we present an overview of the project “Webb Investigation of Silicates, Carbons, and Ices” (WISCI) along with interpretation of two targets, GSC 08152-02121 and CPD-59 5831. Observations of 12 WISCI target stars were taken by JWST, the Hubble Space Telescope, Himalayan Chandra Telescope, and the Very Large Telescope. We use these to characterize the targets’ spectral types and calculate their line-of-sight extinction parameters, A V and R V . We find absorption in the JWST spectra of GSC 08152-02121 and CPD-59 5831 associated with carbonaceous dust around 3.4 and 6.2 μ m and amorphous silicates at 9.7 μ m. In GSC 08152-02121, we also find indications of absorption by trapped water around 3 μ m. This first look from WISCI demonstrates the line-of-sight variability within the sample, and the program’s potential to identify and correlate features across ultraviolet to mid-infrared wavelengths.}, archive = {J_ApJ}, author = {S. T. Zeegers and Jonathan P. Marshall and Karl D. Gordon and Karl A. Misselt and G. P. P. L. Otten and Jeroen Bouwman and Jean Chiar and Marjorie Decleir and Thavisha Dharmawardena and F. Kemper and Aigen Li and Mayank Narang and Alexey Potapov and Manoj Puravankara and Peter Scicluna and Himanshu Tyagi and Eleonora Zari and ChuanYu Wei and Lex Kaper and Frank Backs and Stefan T. Bromley and Laurie Chu and Elisa Costantini and T. R. Geballe and Joel D. Green and Chamani Gunasekera and Burcu Günay and Thomas Henning and Olivia Jones and Joan Mariñoso Guiu and Melissa McClure and Yvonne J. Pendleton and Julia C. Roman-Duval and Tomer Shenar and Alexander G. G. M. Tielens and L. B. F. M. Waters}, doi = {10.3847/1538-4357/add73b}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {25}, shortjournal = {The Astrophys. J.}, title = {Investigating silicate, carbon, and water in the diffuse interstellar medium: The first shots from WISCI}, volume = {987}, year = {2025}, }
• (2025). Bioverse: Potentially observable exoplanet biosignature patterns under the UV threshold hypothesis for the origin of life. ApJ, 987(1), 24. (www)

  @article{ , abstract = {A wide variety of scenarios for the origin of life have been proposed, with many influencing the prevalence and distribution of biosignatures across exoplanet populations. This relationship suggests these scenarios can be tested by predicting biosignature distributions and comparing them with empirical data. Here, we demonstrate this approach by focusing on the cyanosulfidic origins-of-life scenario and investigating the hypothesis that a minimum near-ultraviolet (NUV) flux is necessary for abiogenesis. Using Bayesian modeling and the Bioverse survey simulator, we constrain the probability of obtaining strong evidence for or against this “UV Threshold Hypothesis” with future biosignature surveys. Our results indicate that a correlation between past NUV flux and current biosignature occurrence is testable for sample sizes of ≳50 planets. The diagnostic power of such tests is critically sensitive to the intrinsic abiogenesis rate and host star properties, particularly maximum past NUV fluxes. Surveys targeting a wide range of fluxes, and planets orbiting M dwarfs enhance the chances of conclusive results, with sample sizes ≳100 providing ≳80% likelihood of strong evidence if abiogenesis rates are high and the required NUV fluxes are moderate. For required fluxes exceeding a few hundred erg s −1 cm −2 , both the fraction of inhabited planets and the diagnostic power sharply decrease. Our findings demonstrate the potential of exoplanet surveys to test origins-of-life hypotheses. Beyond specific scenarios, this work underscores the broader value of realistic survey simulations for future observatories (e.g., Habitable Worlds Observatory, LIFE, Extremely Large Telescopes, Nautilus) in identifying testable science questions, optimizing mission strategies, and advancing theoretical and experimental studies of abiogenesis.}, archive = {J_ApJ}, author = {Martin Schlecker and Dániel Apai and Antonin Affholder and Sukrit Ranjan and Régis Ferrière and Kevin K. Hardegree-Ullman and Tim Lichtenberg and Stéphane Mazevet}, doi = {10.3847/1538-4357/adc8a9}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {24}, shortjournal = {The Astrophys. J.}, title = {Bioverse: Potentially observable exoplanet biosignature patterns under the UV threshold hypothesis for the origin of life}, volume = {987}, year = {2025}, }
• (2025). “Oh FUors, where art thou?”: A search for long-lasting young stellar object outbursts hiding in infrared surveys. ApJ, 987(1), 23. (www)

  @article{ , abstract = {Long-lasting episodes of high accretion can strongly impact stellar and planetary formation. However, the universality of these events during the formation of young stellar objects (YSOs) is still under debate. Accurate statistics of strong outbursts (FUors) are necessary to understand the role of episodic accretion bursts. In this work, we search for a population of FUors that may have gone undetected in the past because they either (a) went into outburst before the start of modern monitoring surveys and are now slowly fading back into quiescence or (b) are slow-rising outbursts that would not commonly be classified as candidate FUors. We hypothesize that the light curves of these outbursts should be well fitted by linear models with negative (declining) or positive (rising) slopes. The analysis of the infrared light curves and photometry of ∼99,000 YSO candidates from SPICY yields 717 candidate FUors. Infrared spectroscopy of 20 candidates, from both the literature and obtained by our group, confirms that 18 YSOs are going through long-term outbursts and identifies two evolved sources as contaminants. The number of candidate FUors combined with previously measured values of the frequency of FUor outbursts yields average outburst decay times that are 2.5 times longer than the rise times. In addition, a population of outbursts with rise timescales between 2000 and 5000 days must exist to obtain our observed number of YSOs with positive slopes. Finally, we estimate a mean-burst lifetime of between 45 and 100 yr.}, archive = {J_ApJ}, author = {Carlos Contreras Peña and Jeong-Eun Lee and Ho-Gyu Lee and Gregory Herczeg and Doug Johnstone and Hanpu Liu and Philip W. Lucas and Zhen Guo and Michael A. Kuhn and Leigh C. Smith and Mizna Ashraf and Jessy Jose and Sung-Yong Yoon and Sung-Chul Yoon}, doi = {10.3847/1538-4357/add25f}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {23}, shortjournal = {The Astrophys. J.}, title = {“Oh FUors, where art thou?”: A search for long-lasting young stellar object outbursts hiding in infrared surveys}, volume = {987}, year = {2025}, }
• (2025). Population-level hypothesis testing with rocky planet emission data: A tentative trend in the brightness temperatures of M-earths. ApJ, 987(1), 22. (www)

  @article{ , abstract = {Determining which rocky exoplanets have atmospheres, and why, is a key goal for the James Webb Space Telescope. So far, emission observations of individual rocky exoplanets orbiting M stars (M-Earths) have not provided definitive evidence for atmospheres. Here, we synthesize emission data for M-Earths and find a trend in measured brightness temperatures (ratioed to its theoretical maximum value) as a function of instellation. However, the statistical evidence of this trend is dependent on the choice of stellar model, and we consider its identification tentative. We show that this trend can be explained by either the onset of thin/tenuous (<1 bar) CO 2 -rich atmospheres on colder worlds, or a population of bare rocks with stronger space weathering and/or coarser regolith on closer-in worlds. Such grain coarsening may be caused by sintering near the melting point of rock or frequent volcanic resurfacing. Furthermore, we highlight considerations when testing rocky planet hypotheses at the population level, including the choice of instrument, stellar modeling, and how brightness temperatures are derived. We also find that fresh (unweathered) fine-grained surfaces can serve as a false positive to the detection of moderate atmospheric heat redistribution through eclipse observations. However, we argue that such surfaces are unlikely given the ubiquity of space weathering in the solar system, the low albedo of solar system airless bodies, and the high stellar wind environments of M-Earths. Emission data from a larger sample of M-Earths will be able to confirm or reject this tentative trend and diagnose its cause through spectral characterization.}, archive = {J_ApJ}, author = {Brandon Park Coy and Jegug Ih and Edwin S. Kite and Daniel D. B. Koll and Moritz Tenthoff and Jacob L. Bean and Megan Weiner Mansfield and Michael Zhang and Qiao Xue and Eliza M.-R. Kempton and Kay Wohlfarth and Renyu Hu and Xintong Lyu and Christian Wöhler}, doi = {10.3847/1538-4357/add3f7}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {22}, shortjournal = {The Astrophys. J.}, title = {Population-level hypothesis testing with rocky planet emission data: A tentative trend in the brightness temperatures of M-earths}, volume = {987}, year = {2025}, }
• (2025). Cellular dynamics of helium-rich detonation on sub-chandrasekhar mass white dwarf. ApJ, 987(1), 21. (www)

  @article{ , abstract = {In previous hydrodynamic studies on detonation in the context of Type Ia supernovae (SNe Ia), consideration of cellular structures has been limited in the evaluation of a criterion in initiation, propagation, quenching, and the resolution requirement of detonation, whereas it is quite common to consider cell sizes in the discussion on terrestrial detonation in chemically reactive systems. In our recent study, the terrestrial cell-based theories, which incorporate the cell-size data acquired in two-dimensional simulations of helium detonation in the double-detonation model, were demonstrated to be powerful diagnostics in reproducing the thresholds in the initiation and quenching provided by previous studies. In the present study, two-dimensional simulation results of the cellular detonation in the base of a white dwarf's (WD) envelope are described in detail, in terms of the dynamic wave morphology and chemical abundance structure. The cellular structure is observed at a range of upstream density and envelope composition explored in the present work. C/O contamination by the WD's core material reduces the cell width rapidly, as accelerated by the α -capture reaction. It is also indicated that nickel production could be significantly delayed for the C/O-rich composition. The small cell width requires the detonation structure to be resolved in full-star simulations of SNe Ia, which could raise concerns about the robustness of the outcomes of some numerical simulations in terms of the success and failure of detonation. This issue may be overcome by subgrid modeling that incorporates the cellular dynamics acquired in resolved simulations.}, archive = {J_ApJ}, author = {Kazuya Iwata and Keiichi Maeda}, doi = {10.3847/1538-4357/add5ed}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {21}, shortjournal = {The Astrophys. J.}, title = {Cellular dynamics of helium-rich detonation on sub-chandrasekhar mass white dwarf}, volume = {987}, year = {2025}, }
• (2025). Filamentary hierarchies and superbubbles. i. characterizing filament properties across a simulated spiral galaxy. ApJ, 987(1), 20. (www)

  @article{ , abstract = {High-resolution surveys reveal that the interstellar medium in the Milky Way and nearby galaxies consists of interlinked hierarchies of filamentary structure and superbubbles extending from galactic to subparsec scales. The characterization of filament properties across this hierarchy is of fundamental importance for the origin of giant molecular clouds and their star clusters. In this paper, we characterize the properties of filaments greater than 25 pc in length that are produced in the multiscale galactic MHD simulations of B. Zhao et al. By adapting the FilFinder algorithm of E. W. Koch & E. W. Rosolowsky, we extract over 500 filaments ranging up to 10 kpc in scale, to derive the probability distribution functions for filament masses and lengths, magnetic field orientations, and the gravitational stability and fragmentation patterns of filaments. We find power-law distributions for filament masses and lengths. The former has a power-law index α m = 1.85 that is nearly identical to that of observed giant molecular cloud (GMC) mass functions in extragalactic and Galactic surveys, suggesting that GMC properties are inherited from their host filaments. The fragmentation of magnetized filaments on 200 pc scales or less occurs when they exceed an average critical line mass, as predicted by theory. On larger scales, however, kiloparsec filaments form out of the cold neutral medium, and fragmentation follows local variations in the critical line mass along spiral arms or at the boundaries of superbubbles.}, archive = {J_ApJ}, author = {Rachel Pillsworth and Erica Roscoe and Ralph E. Pudritz and Eric W. Koch}, doi = {10.3847/1538-4357/add68a}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {20}, shortjournal = {The Astrophys. J.}, title = {Filamentary hierarchies and superbubbles. i. characterizing filament properties across a simulated spiral galaxy}, volume = {987}, year = {2025}, }
• (2025). Anisotropic diffusion of e± in pulsar halos over multiple coherence of magnetic fields. ApJ, 987(1), 19. (www)

  @article{ , abstract = {The slow particle diffusion in pulsar halos, inferred from TeV gamma-ray surface brightness profiles (SBPs), is attributed to cross-field diffusion under the anisotropic diffusion model. This model assumes sub-Alfvénic interstellar turbulence in the medium surrounding the pulsar and a rough alignment of the line of sight of observers toward the pulsar with the local mean magnetic field direction in the halo. In this model, the expected morphology of a pulsar halo is highly dependent on the properties of the interstellar magnetic field. We investigate the anisotropic diffusion of electron–positron pairs across multiple coherence of magnetic fields in pulsar halos in this work. We focus particularly on their influence on the predicted gamma-ray SBP and the asymmetry of the halo’s morphology, as well as the observational expectations of the Large High Altitude Air Shower Observatory. Our results indicate that the requirement of a specific magnetic field geometry can be alleviated when accounting for a limited (and realistic) coherence length of the magnetic field in the model. Also, the halo’s morphology may appear less asymmetric, especially after being smoothed by the point-spread function of instruments. This largely relaxes the tension between the asymmetric morphology of halos predicted by the model and the lack of apparent asymmetric halos detected so far. Our findings demonstrate the important influence of the coherence length of the interstellar magnetic field on the distribution of particles around their accelerators, and the consequence for the measured source morphology.}, archive = {J_ApJ}, author = {Kai Yan and Sha Wu and Ruo-Yu Liu}, doi = {10.3847/1538-4357/add6a4}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {19}, shortjournal = {The Astrophys. J.}, title = {Anisotropic diffusion of e± in pulsar halos over multiple coherence of magnetic fields}, volume = {987}, year = {2025}, }
• (2025). Modeling foreground spatial variations in 21 cm gaussian process component separation. ApJ, 987(1), 18. (www)

  @article{ , abstract = {The 21 cm line from neutral hydrogen captures rich cosmological information. However, the 21 cm signals are highly contaminated by foreground emission, making accurate component separation vital for cosmological analyses. Gaussian processes (GPs) have been utilized for component separation in 21 cm data analyses, exploiting the distinct spectral behavior of the cosmological and foreground signals, which are modeled through the GP covariance kernel. Previous approaches have employed a global GP kernel along all lines of sight (LoS). In this work, we study Bayesian approaches that allow for spatial variations in foreground kernel parameters, testing them against simulated H i intensity mapping observations, which measures the total H i intensity in large voxels. We consider a no-pooling (NP) model, treating each LoS independently by fitting for separate covariance kernels, and a hierarchical Gaussian process (HGP) model, allowing for variation in kernel parameters between different LoS, regularized through a global hyperprior. We find that including spatial variations in the GP kernel parameters results in a significant improvement in cosmological signal recovery, achieving up to a 30% reduction in the standard deviation of the residual distribution. Allowing for spatial variations also improves the recovery of the H i power spectra and wavelet scattering transform coefficients. While the NP model achieves superior recovery as measured by the residual distribution, it is computationally demanding, faces convergence challenges, and is prone to overfitting. The HGP model strikes a balance between accuracy and robustness. Further improvements to the HGP model will require more physically-motivated modeling of foreground spatial variations. Our code can be found in the following repository: https://github.com/dkn16/H21F .}, archive = {J_ApJ}, author = {Kangning Diao and Richard D. P. Grumitt and Yi Mao}, doi = {10.3847/1538-4357/add72b}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {18}, shortjournal = {The Astrophys. J.}, title = {Modeling foreground spatial variations in 21 cm gaussian process component separation}, volume = {987}, year = {2025}, }
• (2025). Evaluating the effects of thermal processing on nucleosynthetic zinc isotope variations: Insights from carbonaceous chondrites leachates. ApJ, 987(1), 17. (www)

  @article{ , abstract = {Variations in the nucleosynthetic isotope compositions of meteorites have been suggested to result from variable destruction of some presolar grains through thermal processing. This mechanism has furthermore been linked to volatile depletion in chondritic meteorites. As a moderately volatile element with variable nucleosynthetic isotope compositions, Zn potentially records both processes. Here, we present the nucleosynthetic Zn isotope compositions of leachates that target distinct mineral phases from four carbonaceous chondrites (CCs). The isotopic similarities between some leaching steps imply that different phases were partially homogenized, obscuring the original hosts of the neutron-rich (NR) Zn component that characterizes CCs. However, some leachates of the most primitive sample, Murchison CM2, display distinct Zn isotope compositions. The results reveal that the NR Zn was possibly hosted in silicate or oxide grains, which are similar or identical to the carriers of the bulk of the Zn. Multiple scenarios that simulate preferential Zn loss from such phases were modelled and compared to estimated compositions of thermally processed components in chondrites. The modelling suggests that variable extents of Zn depletion cannot account for the observed variations in nucleosynthetic Zn isotope compositions, implying that these characteristics are decoupled. Instead, distinct isotope compositions are required for the different Zn carriers depending on the chondrite group. The results thus suggest that thermal processing alone is not responsible for the observed nucleosynthetic Zn isotope variations. Rather, they most likely reflect temporal or spatial changes in the composition of the molecular cloud as the protoplanetary disk evolved, in line with other studies.}, archive = {J_ApJ}, author = {Rayssa Martins and Elin M. Morton and Alessandro Bragagni and Helen M. Williams and Frank Wombacher and Mark Rehkämper}, doi = {10.3847/1538-4357/add938}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {17}, shortjournal = {The Astrophys. J.}, title = {Evaluating the effects of thermal processing on nucleosynthetic zinc isotope variations: Insights from carbonaceous chondrites leachates}, volume = {987}, year = {2025}, }
• (2025). Repeated tidal interactions between stars and supermassive black holes: Mass transfer, stability, and implications for repeating partial tidal disruption events. ApJ, 987(1), 16. (www)

  @article{ , abstract = {Stars orbiting supermassive black holes can generate recurring accretion flares in repeating partial tidal disruption events (TDEs). Here, we develop an efficient formalism for analyzing the time-dependent response of a star to the removal of a fraction (≲10%) of its mass. This model predicts that mass loss results in a decrease in the average density of low-mass (≲0.7 M ⊙ ) stars. In contrast, higher-mass stars exhibit an increase in their average density, such that the change is more pronounced for larger mass losses, and stars with masses ∼1.5−2 M ⊙ experience the largest such increase. We predict that the final energy of the star post-mass-loss (i.e., the “surviving core”) is effectively given by the binding energy of the original star interior to the radius from which mass is removed, i.e., the final core energy is agnostic to the process that removes the mass and—as a corollary—tidal heating is comparatively insignificant. We find excellent agreement between our predictions and one-dimensional Eulerian simulations of a star undergoing mass loss, and three-dimensional Lagrangian simulations of partial TDEs. We conclude that (1) partially disrupted stars are not significantly heated via tidal dissipation, (2) evolved and moderately massive (≳1.5 M ⊙ ) stars can most readily survive many repeated stripping events, and (3) progressively dimmer flares—observed in some repeating partial TDE candidates—could be explained by the increase in the density of the star post-mass-loss.}, archive = {J_ApJ}, author = {Ananya Bandopadhyay and Eric R. Coughlin and C. J. Nixon}, doi = {10.3847/1538-4357/add9a5}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {16}, shortjournal = {The Astrophys. J.}, title = {Repeated tidal interactions between stars and supermassive black holes: Mass transfer, stability, and implications for repeating partial tidal disruption events}, volume = {987}, year = {2025}, }
• (2025). Energetic neutral atom fluxes from the voyager 1 and 2 directions. ApJ, 987(1), 15. (www)

  @article{ , abstract = {IBEX observes a globally distributed energetic neutral atom (ENA) flux from the heliosheath and very local interstellar medium (VLISM). Over a 14 yr period, Voyager 1 and Voyager 2 traversed the heliosheath from the termination shock to the heliopause. In situ observations from these spacecraft place important constraints on the parent ion populations of the ENAs from the heliosheath in two directions on the upwind side of the heliosphere, i.e., the direction of motion of the Sun in the local interstellar medium. In this study, an MHD model that is constrained by Voyager in situ observations is used to estimate the contribution from the heliosheath to the total ENA fluxes observed by IBEX. At energies greater than about 0.5 keV, the heliosheath provides a significant fraction of the observed ENA flux. However, at energies less than about 0.5 keV, the heliosheath provides an insignificant fraction of the observed ENA flux. These results are the same for both directions, and since the Voyager 1 and 2 directions are not particularly unique, the results are likely to be applicable for much of the upwind hemisphere. Fundamentally, it is the physics of the termination shock and the thickness of the heliosheath that determine the energy-dependent contributions to the observed ENA flux from this region. Because the heliosheath source is insignificant, most ENAs at energies less than about 0.5 keV probably come from the VLISM.}, archive = {J_ApJ}, author = {Stephen A. Fuselier and Eric J. Zirnstein and Jacob Heerikhuisen and André Galli and John D. Richardson and Daniel B. Reisenfeld and Nathan A. Schwadron and Maher A. Dayeh and David J. McComas and Herbert O. Funsten and Justyna M. Sokół and Merav Opher and Marc Z. Kornbleuth and Jonathan Gasser}, doi = {10.3847/1538-4357/addd12}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {15}, shortjournal = {The Astrophys. J.}, title = {Energetic neutral atom fluxes from the voyager 1 and 2 directions}, volume = {987}, year = {2025}, }
• (2025). A composite broad-line region in SDSS j1609+4902: A double-peaked disk component and a gaussian component. ApJ, 987(1), 14. (www)

  @article{ , abstract = {The profiles of broad emission lines in active galactic nuclei (AGNs) provide critical insights into the geometry and kinematics of the broad-line region (BLR), which in turn influence the uncertainties in estimating the masses of central supermassive black holes. In this study, we report the discovery of a low-luminosity AGN, SDSS J1609+4902, in which the H α line exhibits two distinct BLR components: a Gaussian component and an extremely broad double-peaked component. Follow-up observations conducted at the Lijiang Observatory in 2025 reveal that the line profile remains roughly unchanged, suggesting that this BLR structure may remain stable over a timescale of ∼10 yr. We find that the size of the central Gaussian (full width at half-maximum, FWHM ∼ 3000 km s −1 ) component is consistent with the classical reverberation mapping correlation. In contrast, the asymmetric double-peaked wing (FWHM ∼ 23,000 km s −1 ) likely originates from a disk-like BLR with an inner radius of approximately 70 gravitational radii. These results provide new constraints on the structure and dynamics of BLRs in AGNs and highlight the potential for long-term stability in such systems.}, archive = {J_ApJ}, author = {Jiancheng Wu and Qingwen Wu and Chen Hu and Bing Lyu and Hua-Rui Bai and Yi-Xin Fu and Yu Zhao and Jian-Min Wang and Xinwu Cao}, doi = {10.3847/1538-4357/ade2cc}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {14}, shortjournal = {The Astrophys. J.}, title = {A composite broad-line region in SDSS j1609+4902: A double-peaked disk component and a gaussian component}, volume = {987}, year = {2025}, }
• (2025). Unveiling the diversity of type IIn supernovae via systematic light-curve modeling. ApJ, 987(1), 13. (www)

  @article{ , abstract = {Type IIn supernovae (SNe IIn) are a highly heterogeneous subclass of core-collapse supernovae, spectroscopically characterized by signatures of interaction with a dense circumstellar medium (CSM). Here, we systematically model the light curves of 142 archival SNe IIn using the Modular Open Source Fitter for Transients. We find that the observed and inferred properties of SN IIn are diverse, but there are some trends. The typical supernova CSM is dense (∼10 −12 g cm −3 ) with highly diverse CSM geometry, with a median CSM mass of ∼1 M ⊙ . The ejecta are typically massive (≳10 M ⊙ ), suggesting massive progenitor systems. We find positive correlations between the CSM mass and the rise and fall times of SNe IIn. Furthermore, there are positive correlations between the rise time and fall times and the r -band luminosity. We estimate the mass-loss rates of our sample (where spectroscopy is available) and find a high median mass-loss rate of ∼10 −2 M ⊙ yr −1 , with a range between 10 −3 and 1 M ⊙ yr −1 . These mass-loss rates are most similar to the mass loss from great eruptions of luminous blue variables, consistent with the direct progenitor detections in the literature. We also discuss the role that binary interactions may play, concluding that at least some of our SNe IIn may be from massive binary systems. Finally, we estimate a detection rate of 1.6 × 10 5 yr −1 in the upcoming Legacy Survey of Space and Time at the Vera C. Rubin Observatory.}, archive = {J_ApJ}, author = {C. L. Ransome and V. A. Villar}, doi = {10.3847/1538-4357/adce03}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {13}, shortjournal = {The Astrophys. J.}, title = {Unveiling the diversity of type IIn supernovae via systematic light-curve modeling}, volume = {987}, year = {2025}, }
• (2025). Bursts of star formation and radiation-driven outflows produce efficient LyC leakage from dense compact star clusters. ApJ, 987(1), 12. (www)

  @article{ , abstract = {The escape of LyC photons emitted by massive stars from the dense interstellar medium (ISM) of galaxies is a key bottleneck for cosmological reionization. The escape fraction varies significantly across and within galaxies, motivating further study of the underlying physical factors responsible for these trends. We perform radiation hydrodynamic simulations of idealized clouds with different gas surface densities (compactness) Σ ∼ 10 2 –10 5 M ⊙ pc −2 , meant to emulate star cluster-forming clumps ranging from conditions typical of the local Universe to the high ISM-pressure conditions encountered at high redshift. We find that dense compact star clusters with Σ ≳ 10 4 M ⊙ pc −2 efficiently leak LyC photons, with cloud-scale luminosity-weighted average escape fractions ≳80% as opposed to ≲10% for Σ ∼ 100 M ⊙ pc −2 . This occurs due to higher star formation efficiencies and shorter dynamical timescales at higher Σ; the former results in higher intrinsic LyC emission, and the latter implies rapid evolution, with a burst of star formation followed by rapid gas dispersal, permitting high LyC escape well before the intrinsic LyC emission of stellar populations drop (∼4 Myr). LyC escape in dense clouds is primarily facilitated by highly ionized outflows driven by radiation pressure on dust with velocities ∼3 times the cloud escape velocity. We also vary the (assumed) dust abundances ( Z d ) and find a mild increase (∼10%) in the escape fraction for ∼100 lower Z d . Our results suggest a scenario in which localized compact bursts of star formation in galaxies are disproportionately productive sites of LyC leakage. We briefly discuss possible observational evidence for our predictions and implications for cosmic reionization.}, archive = {J_ApJ}, author = {Shyam H. Menon and Blakesley Burkhart and Rachel S. Somerville and Todd A. Thompson and Amiel Sternberg}, doi = {10.3847/1538-4357/add2f9}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {12}, shortjournal = {The Astrophys. J.}, title = {Bursts of star formation and radiation-driven outflows produce efficient LyC leakage from dense compact star clusters}, volume = {987}, year = {2025}, }
• (2025). A pilot method to determine the high mass end of the stellar initial mass function in galaxies using UVIT, hα-MUSE observations and applied to NGC 628. ApJ, 987(1), 11. (www)

  @article{ , abstract = {We present a pilot method to estimate the high-mass initial mass function (IMF) across the arm, interarm, and spur regions in galaxies and apply it to NGC 628. We extracted star-forming complexes (SFCs) from the H α Very Large Telescope/Multi Unit Spectroscopic Explorer and Ultraviolet Imaging Telescope (far-ultraviolet (FUV) and near-ultraviolet (NUV)) observations of NGC 628 and used Atacama Large Millimeter/submillimeter Array observations to define the molecular gas distribution. We find that the extinction-corrected H α and FUV luminosities correlate well. Using the fact that O stars have a shorter lifetime (10 7 yr) compared to B stars (10 8 yr), we estimated the approximate number of O stars from H α emission, and the number of B0 ( M * > 10 M ⊙ ), and B1 (10 M ⊙ ≥ M * ≥ 3 M ⊙ ) stars using FUV and NUV observations. We derived the IMF index ( α ) for different regions using O to B0 ( α 1 ) and B0 to B1 ( α 2 ) stellar ratios. Our findings indicate that if we assume H α arises only from O8-type stars, the resulting α 1 value is consistent with the canonical IMF index. It steepens when we assume O stars with masses up to 100 M ⊙ with mean α 1 = 3.16 ± 0.62. However, the α 2 does not change for large variations in the O-star population, and the mean α = 2.64 ± 0.14. When we include only blue SFCs (FUV − NUV ≤ 0.3), mean α 2 is 2.43 ± 0.06. The IMF variation for SFCs in arms and spurs is insignificant. We also find that α 2 correlates with different properties of the SFCs, the most prominent being the extinction-corrected UV color (FUV − NUV).}, archive = {J_ApJ}, author = {S Amrutha and Mousumi Das}, doi = {10.3847/1538-4357/add68d}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {11}, shortjournal = {The Astrophys. J.}, title = {A pilot method to determine the high mass end of the stellar initial mass function in galaxies using UVIT, hα-MUSE observations and applied to NGC 628}, volume = {987}, year = {2025}, }
• (2025). Circular mystery: Exploring diffuse emission surrounding a radio galaxy with uGMRT and VLA multiwavelength observations. ApJ, 987(1), 10. (www)

  @article{ , abstract = {We report the discovery of J1218+1813, a circular diffuse radio source detected in the Very Large Array (VLA) FIRST survey at 1400 MHz. The source has an angular diameter of approximately one arcminute, corresponding to a physical size of ∼180 kpc, and is associated with an elliptical galaxy with a redshift of z = 0.139635. To investigate its nature, we conducted a comprehensive multiwavelength analysis spanning both high and low radio frequencies, utilizing the VLA in C-configuration at L , C and X bands, along with the upgraded Giant Metrewave Radio Telescope (uGMRT) at bands 3 (250–500 MHz), 4 (550–850 MHz), and 5 (1000–1260 MHz). A spectral study based on these multiwavelength observations reveals that the core of J1218+1813 exhibits a steep spectral index of 0.8, indicating that the emission is dominated by optically thin synchrotron radiation. The spectral index varies between 1.1 and 1.8, from the inner to the outer structure, with the steepest values observed at the periphery of the diffuse emission. An optical analysis of the central host galaxy using spectroscopic data is also performed. The estimated black hole mass is 2.8 ± 0.8 × 10 8 M ⊙ , while the host galaxy has a stellar mass of 2.9 × 10 11 M ⊙ and a stellar age of 8.58 Gyr. The identification of J1218+1813 is particularly significant because it provides insight into the mechanisms responsible for the formation of circular diffuse radio structures surrounded by an elliptical galaxy. Potential formation scenarios for J1218+1813 are discussed in this paper.}, archive = {J_ApJ}, author = {Shobha Kumari and Sabyasachi Pal and Souvik Manik}, doi = {10.3847/1538-4357/add69d}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {10}, shortjournal = {The Astrophys. J.}, title = {Circular mystery: Exploring diffuse emission surrounding a radio galaxy with uGMRT and VLA multiwavelength observations}, volume = {987}, year = {2025}, }
• (2025). Surprising Spin–Orbit resonances of rocky planets. ApJ, 987(1), 9. (www)

  @article{ , abstract = {Recent works suggest that, in multiplanetary systems, a close-in exoplanet can sometimes avoid becoming tidally locked to its host star if it is captured into a secular spin–orbit resonance with a companion planet. In such a resonance, the planet remains at a subsynchronous spin rate and an appreciable obliquity (the planet’s spin–orbit misalignment angle). However, many of these works have only considered planets with fluid-like rheologies. Recent observations suggest that planets up to a few Earth masses may be rocky and thus may have an appreciable rigidity. In this work, we study the spin–orbit dynamics of such rigid planets using a linear dissipative tidal model and not enforcing principal-axis rotation about the body’s shortest principal axis. We identify a new class of spin–orbit resonances when the planet spins at twice its orbital frequency. These resonances exist at nonzero obliquity and spontaneously excite non-principal-axis rotation upon resonance capture. While these resonances eventually disappear as tidal dissipation damps the obliquity to zero (and the body returns to principal-axis rotation), they still modify the spin evolutionary history of the planet. Such resonances may enhance the prevalence of secular spin–orbit resonances in exoplanetary systems.}, archive = {J_ApJ}, author = {Henry D. A. Yuan and Yubo Su and Jeremy Goodman}, doi = {10.3847/1538-4357/add2f3}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {9}, shortjournal = {The Astrophys. J.}, title = {Surprising Spin–Orbit resonances of rocky planets}, volume = {987}, year = {2025}, }
• (2025). New rotation periods from the kepler bonus background light curves. ApJ, 987(1), 8. (www)

  @article{ , abstract = {The Kepler field hosts the best-studied sample of field star rotation periods. However, due to Kepler’s large 4″ pixels, many of its light curves are at high risk of contamination from background sources. The new Kepler Bonus Background light curves are deblended using a point-spread function algorithm, providing light curves of over 400,000 new background sources in addition to over 200,000 reanalyzed Kepler prime targets. These light curves provide the opportunity to search for new rotation periods. Here we apply a convolutional neural network trained on synthetic spot-modulated light curves to regress rotation periods from the Kepler Bonus light curves. We obtained periods for 32,159 total sources, 19,650 of which had previously been measured and 9811 of which are new periods for both Kepler prime and background sources. Our method also detected 608 pulsation frequencies from asteroseismic oscillations in red giants. We validate our Kepler prime periods against literature values and present the full period sample. We find excellent agreement with previously known literature periods, validating deep learning as a viable class of period determination methods. Comparing the periods and light curves of foreground–background pairs, we find that as many as 63% of periodic background light curves are still blended with the foreground, highlighting the limitations of the deblending technique.}, archive = {J_ApJ}, author = {Zachary R. Claytor and Jamie Tayar}, doi = {10.3847/1538-4357/add5f0}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {8}, shortjournal = {The Astrophys. J.}, title = {New rotation periods from the kepler bonus background light curves}, volume = {987}, year = {2025}, }
• (2025). Main-oval auroral emission from a t6 brown dwarf: Observations, modeling, and astrometry. ApJ, 987(1), 7. (www)

  @article{ , abstract = {From a series of 5 GHz Very Long Baseline Array (VLBA) radio observations taken over a 1 yr span, we present the detection of compact, highly polarized radio emission from the T6 brown dwarf WISE J112254.72+255022.2, compatible with electron cyclotron maser emission. Both the total and polarized lightcurves show variability in correspondence with a rotation period of 1.95 ± 0.03 hr. Comparison with models indicates that the quasi-steady radio emission of this brown dwarf is produced in circumpolar auroral rings, with remarkable similarity to the main-oval auroras in Jupiter. We have detected a large 100% polarized flare in one of the VLBA epochs (2022.82), which may imply the existence of active longitudes in the auroral rings with a nonaxisymmetric beaming cone radiation pattern, similar to the dusk/dawn asymmetries seen in the Jovian radio emissions. We also present a high-precision astrometric analysis of the sky motion of WISE J112254.72+255022.2, resulting in revised values of proper motion and parallax with an improvement in precision of 1 order of magnitude. The common kinematics of WISE J112254.72+255022.2 with its wide companion, the M dwarf LHS 302, is confirmed with submilliarcsecond precision, suggesting that this brown dwarf may have formed by gravitational fragmentation of the outer part of a protostellar disk around LHS 302. The astrometric analysis imposes very tight bounds on the presence of low-mass companions around WISE J112254.72+255022.2, ruling out objects more massive than Saturn. Our results strengthen the analogy between radio-emitting brown dwarfs and the magnetized planets of our solar system.}, archive = {J_ApJ}, author = {J. C. Guirado and J. B. Climent and J. D. Bergasa and M. A. Pérez-Torres and J. M. Marcaide and L. Peña-Moñino}, doi = {10.3847/1538-4357/add5f3}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {7}, shortjournal = {The Astrophys. J.}, title = {Main-oval auroral emission from a t6 brown dwarf: Observations, modeling, and astrometry}, volume = {987}, year = {2025}, }
• (2025). Delayed thermal relaxation of rapid cooling neutron stars: Nucleon superfluidity and nonnucleon particles. ApJ, 987(1), 6. (www)

  @article{ , abstract = {The thermal relaxation time of neutron stars, typically defined by a sudden drop in surface temperature, is usually on the order of 10–100 yr. In this study, we investigate neutron star thermal relaxation by incorporating nucleon superfluidity and nonnucleonic particles, specifically considering hyperons as a representative case. We find that rapidly cooling neutron stars driven by neutron superfluidity and direct Urca processes demonstrate delayed thermal relaxation under specific physical conditions. The former requires that the neutron 3 P 2 critical temperature is small enough, whereas the latter depends on the presence of a small core that permits direct Urca processes. To explore these scenarios, we propose simple theoretical frameworks to describe these delayed thermal relaxation behaviors and discuss how a recently established enhanced modified Urca rate influences the relaxation time. By confronting the theoretical results with the observation of Cassiopeia A, we can effectively constrain the maximum neutron 3 P 2 critical temperature.}, archive = {J_ApJ}, author = {Zhonghao Tu and Ang Li}, doi = {10.3847/1538-4357/add734}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {6}, shortjournal = {The Astrophys. J.}, title = {Delayed thermal relaxation of rapid cooling neutron stars: Nucleon superfluidity and nonnucleon particles}, volume = {987}, year = {2025}, }
• (2025). The NANOGrav 15 yr data set: Search for gravitational-wave memory. ApJ, 987(1), 5. (www)

  @article{ , abstract = {We present the results of a search for nonlinear gravitational-wave (GW) memory in the NANOGrav 15 yr data set. We find no significant evidence for memory signals in the data set, with a maximum Bayes factor of 3.1 in favor of a model including memory. We therefore place upper limits on the strain of potential GW memory events as a function of sky location and observing epoch. We find upper limits that are not always more constraining than previous NANOGrav results. We show that it is likely due to the increase in common red noise between the 12.5 and 15 yr NANOGrav data sets.}, archive = {J_ApJ}, author = {Gabriella Agazie and Akash Anumarlapudi and Anne M. Archibald and Zaven Arzoumanian and Jeremy G. Baier and Paul T. Baker and Bence Bécsy and Laura Blecha and Adam Brazier and Paul R. Brook and Sarah Burke-Spolaor and Rand Burnette and J. Andrew Casey-Clyde and Maria Charisi and Shami Chatterjee and Tyler Cohen and James M. Cordes and Neil J. Cornish and Fronefield Crawford and H. Thankful Cromartie and Kathryn Crowter and Megan E. DeCesar and Paul B. Demorest and Heling Deng and Lankeswar Dey and Timothy Dolch and Elizabeth C. Ferrara and William Fiore and Emmanuel Fonseca and Gabriel E. Freedman and Emiko C. Gardiner and Nate Garver-Daniels and Peter A. Gentile and Kyle A. Gersbach and Joseph Glaser and Deborah C. Good and Kayhan Gültekin and Jeffrey S. Hazboun and Ross J. Jennings and Aaron D. Johnson and Megan L. Jones and David L. Kaplan and Luke Zoltan Kelley and Matthew Kerr and Joey S. Key and Nima Laal and Michael T. Lam and William G. Lamb and Bjorn Larsen and T. Joseph W. Lazio and Natalia Lewandowska and Tingting Liu and Duncan R. Lorimer and Jing Luo and Ryan S. Lynch and Chung-Pei Ma and Dustin R. Madison and Alexander McEwen and James W. McKee and Maura A. McLaughlin and Natasha McMann and Bradley W. Meyers and Patrick M. Meyers and Chiara M. F. Mingarelli and Andrea Mitridate and Priyamvada Natarajan and Cherry Ng and David J. Nice and Stella Koch Ocker and Ken D. Olum and Timothy T. Pennucci and Benetge B. P. Perera and Polina Petrov and Nihan S. Pol and Henri A. Radovan and Scott M. Ransom and Paul S. Ray and Jessie C. Runnoe and Alexander Saffer and Shashwat C. Sardesai and Ann Schmiedekamp and Carl Schmiedekamp and Kai Schmitz and Brent J. Shapiro-Albert and Xavier Siemens and Joseph Simon and Magdalena S. Siwek and Sophia V. Sosa Fiscella and Ingrid H. Stairs and Daniel R. Stinebring and Kevin Stovall and Jerry P. Sun and Abhimanyu Susobhanan and Joseph K. Swiggum and Jacob Taylor and Stephen R. Taylor and Jacob E. Turner and Caner Unal and Michele Vallisneri and Rutger van Haasteren and Sarah J. Vigeland and Haley M. Wahl and Caitlin A. Witt and David Wright and Olivia Young}, doi = {10.3847/1538-4357/add874}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {5}, shortjournal = {The Astrophys. J.}, title = {The NANOGrav 15 yr data set: Search for gravitational-wave memory}, volume = {987}, year = {2025}, }
• (2025). The dependence of dark matter halo properties on the morphology of their central galaxies from weak lensing. ApJ, 987(1), 4. (www)

  @article{ , abstract = {Xu & Jing reported a monotonic relationship between the host halo mass M h and the morphology of massive central galaxies, characterized by the Sérsic index n , at fixed stellar mass, suggesting that morphology could serve as a good secondary proxy for the halo mass. Since their results were derived using the indirect abundance matching method, we further investigate the connection between the halo properties and central galaxy morphology using weak gravitational lensing. We apply galaxy–galaxy lensing to measure the excess surface density around CMASS central galaxies with stellar masses in the range of 11.3\lt \mathrm{log}{{M}}_{* }/{{M}}_{\odot }\lt 11.7 , using the Hyper Suprime-Cam shear catalog processed through the Fourier_Quad pipeline. By dividing the sample based on n , we confirm a positive correlation between n and M h , and observe possible evidence of the positive correlation of n and halo concentration. After accounting for color, we find that neither color nor morphology alone can determine the halo mass, suggesting that a combination of both may serve as a better secondary proxy. In comparison to hydrodynamic simulations, we find that TNG300 produces much weaker correlations between M h and n . Furthermore, using SIMBA simulations with different feedback modes, we find that jet-mode active galactic nuclei feedback might be related to the relationship between the Sérsic index and halo mass.}, archive = {J_ApJ}, author = {Zhenjie Liu and Kun Xu and Jun Zhang and Wenting Wang and Cong Liu}, doi = {10.3847/1538-4357/add883}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {4}, shortjournal = {The Astrophys. J.}, title = {The dependence of dark matter halo properties on the morphology of their central galaxies from weak lensing}, volume = {987}, year = {2025}, }
• (2025). The initial evolution of SN 1993J: Piston phase versus standard model. ApJ, 987(1), 3. (www)

  @article{ , abstract = {The evolution of SN 1993J is unlikely to be self-similar. Spatially resolved very long baseline interferometry observations show that the velocity of the outer rim of the radio emission region breaks at a few hundred days. The reason for this break remains largely unknown. It is argued here that it is due to the transition between an initial piston phase to a later phase, which is described by the standard model. The properties of the reverse shock are quite different for a piston phase as compared to the standard self-similar model. This affects the expected X-ray emission; for example, the reverse shock becomes transparent to X-ray emission much earlier in the piston phase. Furthermore, it is shown that the observed box-like emission line profiles of H α and other optical lines are consistent with an origin from the transition region between the envelope and the core. It is also pointed out that identifying the observed, simultaneous breaks at ≈3100 days in the radio and X-ray light curves with the reverse shock reaching the core makes it possible to directly relate the mass-loss rate of the progenitor star to observables.}, archive = {J_ApJ}, author = {C.-I. Björnsson}, doi = {10.3847/1538-4357/add92f}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {3}, shortjournal = {The Astrophys. J.}, title = {The initial evolution of SN 1993J: Piston phase versus standard model}, volume = {987}, year = {2025}, }
• (2025). Shock wave ram pressure and global evolution of the cygnus loop. ApJ, 987(1), 2. (www)

  @article{ , abstract = {We assess the diagnostic for shock wave ram pressure, \rho {V}_{s}^{2}\,\propto \,{I}_{[{\rm{O}}\,\mathrm{III}]}\,{V}_{\mathrm{Dopp}} , and apply it to high-resolution multifiber spectra of the Cygnus Loop. We find that, while there are many caveats, and while high-resolution profiles are important for controlling some sources of error, the diagnostic is reliable if one selects positions with simple line profiles that are offset away from zero velocity. The Cygnus Loop shows a range of conditions from ≈400 km s −1 nonradiative shocks that produce X-rays to ≈100 km s −1 radiative shocks that produce bright optical emission. We find a range of ram pressures in agreement with previous estimates from [O iii ] and from X-ray measurements. The ram pressure is also consistent with recent analysis of the evolutionary stage of the Cygnus Loop.}, archive = {J_ApJ}, author = {John C. Raymond and Nelson Caldwell and Ji Yeon Seok and Bon-Chul Koo}, doi = {10.3847/1538-4357/add99b}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {2}, shortjournal = {The Astrophys. J.}, title = {Shock wave ram pressure and global evolution of the cygnus loop}, volume = {987}, year = {2025}, }
• (2025). Solar surface magnetic field simulation from 2010 to 2024 and anomalous southern poleward flux transport in cycle 24. ApJ, 987(1), 1. (www)

  @article{ , abstract = {The solar surface magnetic field is fundamental for modeling the coronal magnetic field, studying the solar dynamo, and predicting solar cycle strength. We perform a continuous simulation of the surface magnetic field from 2010 to 2024, covering solar cycle 24 and the ongoing cycle 25, using the surface flux transport model with assimilated observed active regions (ARs) as the source. The simulation reproduces the evolution of the axial dipole strength, polar field reversal timing, and magnetic butterfly diagram in good agreement with Solar Dynamics Observatory/Helioseismic and Magnetic Imager observations. Notably, these results are achieved without incorporating radial diffusion or cyclic variations in meridional flow speed, suggesting their limited impact. Poleward surges of the following polarity typically dominate throughout the cycle, but in the southern hemisphere during cycle 24, they are limited to a short period from 2011 to 2016. This anomalous pattern arises from intermittent AR emergence, with about 46% of the total unsigned flux contributed by ARs emerging during Carrington rotations 2141–2160 (2013 September–2015 February). These ARs show a strong active longitude at Carrington longitudes 200°−260° and a weaker one at 80°−100°. After 2016, poleward migrations of leading-polarity flux become dominant, despite most ARs following Joy’s and Hale’s laws. This reversal is likely due to prolonged intervals between AR emergences, which allow the leading-polarity flux to distribute across a broad latitude range before cancellation by subsequent ARs. These findings highlight the importance of the temporal interval of AR emergence in driving the flux transport pattern.}, archive = {J_ApJ}, author = {Ruihui Wang and Jie Jiang and Yukun Luo}, doi = {10.3847/1538-4357/addf43}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {1}, shortjournal = {The Astrophys. J.}, title = {Solar surface magnetic field simulation from 2010 to 2024 and anomalous southern poleward flux transport in cycle 24}, volume = {987}, year = {2025}, }
• (2025). Erratum: “A maximum likelihood calibration of the tip of the red giant branch luminosity from high latitude field giants using gaia early data release 3 parallaxes” (2022, ApJ, 939, 96). ApJ, 986(2), 234. (www)

  @article{ , archive = {J_ApJ}, author = {Siyang Li and Stefano Casertano and Adam G. Riess}, doi = {10.3847/1538-4357/add2fb}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {234}, shortjournal = {The Astrophys. J.}, title = {Erratum: “A maximum likelihood calibration of the tip of the red giant branch luminosity from high latitude field giants using gaia early data release 3 parallaxes” (2022, ApJ, 939, 96)}, volume = {986}, year = {2025}, }
• (2025). Erratum: “Alternative methylated biosignatures. i. methyl bromide, a capstone biosignature” (2022, ApJ, 938, 6). ApJ, 986(2), 233. (www)

  @article{ , archive = {J_ApJ}, author = {Michaela Leung and Edward W. Schwieterman and Mary N. Parenteau and Thomas J. Fauchez}, doi = {10.3847/1538-4357/add9a2}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {233}, shortjournal = {The Astrophys. J.}, title = {Erratum: “Alternative methylated biosignatures. i. methyl bromide, a capstone biosignature” (2022, ApJ, 938, 6)}, volume = {986}, year = {2025}, }
• (2025). Erratum: “Flare-accelerated electrons in the kappa distribution from X-ray spectra with the warm-target model” (2024, ApJ, 974, 119). ApJ, 986(2), 232. (www)

  @article{ , archive = {J_ApJ}, author = {Yingjie Luo and Eduard P. Kontar and Debesh Bhattacharjee}, doi = {10.3847/1538-4357/addb4f}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {232}, shortjournal = {The Astrophys. J.}, title = {Erratum: “Flare-accelerated electrons in the kappa distribution from X-ray spectra with the warm-target model” (2024, ApJ, 974, 119)}, volume = {986}, year = {2025}, }
• (2025). Union through UNITY: Cosmology with 2000 SNe using a unified bayesian framework. ApJ, 986(2), 231. (www)

  @article{ , abstract = {Type Ia supernovae (SNe Ia) were instrumental in establishing the acceleration of the Universe's expansion. By virtue of their combination of distance reach, precision, and prevalence, they continue to provide key cosmological constraints, complementing other cosmological probes. Individual SN surveys cover only over about a factor of 2 in redshift, so compilations of multiple SN data sets are strongly beneficial. We assemble an up-to-date "Union" compilation of 2087 cosmologically useful SNe Ia from 24 data sets ("Union3"). We take care to put all SNe on the same distance scale and update the light-curve fitting with SALT3 to use the full rest-frame optical. Over the next few years, the number of cosmologically useful SNe Ia will increase by more than a factor of 10, and keeping systematic uncertainties subdominant will be more challenging than ever. We discuss the importance of treating outliers, selection effects, light-curve shape/color populations/standardization relations, unexplained dispersion, and heterogeneous observations simultaneously. We present an updated Bayesian framework, called UNITY1.5 (Unified Nonlinear Inference for Type-Ia cosmologY), that incorporates significant improvements in our ability to model selection effects, standardization, and systematic uncertainties compared to earlier analyses. As an analysis byproduct, we also recover the posterior of the SN-only peculiar-velocity field, although we do not interpret it in this work. We compute updated cosmological constraints with Union3 and UNITY1.5, finding weak 1.7 σ –2.6 σ tension with flat cold dark matter and possible evidence for thawing dark energy ( w 0 > − 1, w a < 0). We release our SN distances, light-curve fits, and UNITY1.5 framework to the community.}, archive = {J_ApJ}, author = {David Rubin and Greg Aldering and Marc Betoule and Andy Fruchter and Xiaosheng Huang and Alex G. Kim and Chris Lidman and Eric Linder and Saul Perlmutter and Pilar Ruiz-Lapuente and Nao Suzuki}, doi = {10.3847/1538-4357/adc0a5}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {231}, shortjournal = {The Astrophys. J.}, title = {Union through UNITY: Cosmology with 2000 SNe using a unified bayesian framework}, volume = {986}, year = {2025}, }
• (2025). Model choice matters for age inference on the red giant branch. ApJ, 986(2), 229. (www)

  @article{ , abstract = {Galactic archaeology relies on accurate stellar parameters to reconstruct the Galaxy's history, including information on stellar ages. While the precision of data has improved significantly in recent years, stellar models used for age inference have not improved at a similar rate. In fact, different models yield notably different age predictions for the same observational data. In this paper, we assess the difference in age predictions of various widely used model grids for stars along the red giant branch. Using open-source software, we conduct a comparison of four different evolution grids, and we find that age estimations become less reliable if stellar mass is not known, with differences occasionally exceeding 80%. Additionally, we note significant disagreements in the models' age estimations at nonsolar metallicity. Finally, we present a method for including theoretical uncertainties from stellar evolutionary tracks in age inferences of red giants, aimed at improving the accuracy of age estimation techniques used in the galactic archaeology community.}, archive = {J_ApJ}, author = {Leslie M. Morales and Jamie Tayar and Zachary R. Claytor}, doi = {10.3847/1538-4357/add2f5}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {229}, shortjournal = {The Astrophys. J.}, title = {Model choice matters for age inference on the red giant branch}, volume = {986}, year = {2025}, }
• (2025). Electron-scale magnetic holes generation driven by whistler-to-bernstein mode conversion in fully kinetic plasma turbulence. ApJ, 986(2), 228. (www)

  @article{ , abstract = {Magnetic holes (MHs) are coherent structures characterized by a strong and localized magnetic field amplitude dip, commonly observed in the heliosphere. These structures come in different sizes, from magnetohydrodynamic to kinetic scales. Subion-scale MHs are usually sustained by an electron current vortex and exhibit a strong electron temperature anisotropy, with higher temperatures perpendicular to the background magnetic field. Magnetospheric multiscale observations (MMSs) have revealed electron-scale MHs to be ubiquitous in the turbulent Earth's magnetosheath and the solar wind, potentially playing an important role in the energy cascade and dissipation. Despite abundant observations, the origin of electron-scale MHs is still unclear and debated. In this work, we use fully kinetic simulations to investigate the role of plasma turbulence in generating electron-scale MHs. We find that the turbulence spontaneously produces electron-scale MHs via the following mechanism: first, large-scale turbulent velocity shears produce regions with high electron temperature anisotropy; these localized regions become unstable, generating oblique electron-scale whistler waves; as they propagate over the inhomogeneous turbulent background, whistler fluctuations develop an electrostatic component, turning into Bernstein-like modes; the strong electrostatic fluctuations produce current filaments that merge into an electron-scale current vortex; the resulting electron vortex locally reduces the magnetic field amplitude, finally evolving into an electron-scale MH. We show that MHs generated by this mechanism have properties consistent with MMSs and nontrivial kinetic features with a "mushroom"-shaped electron velocity distribution function. Our results have potential implications for understanding the formation and occurrence of electron-scale MHs in astrophysical turbulent and space environments, such as the Earth's magnetosheath and the solar wind.}, archive = {J_ApJ}, author = {Joaquín Espinoza-Troni and Giuseppe Arrò and Felipe A Asenjo and Pablo S Moya}, doi = {10.3847/1538-4357/add537}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {228}, shortjournal = {The Astrophys. J.}, title = {Electron-scale magnetic holes generation driven by whistler-to-bernstein mode conversion in fully kinetic plasma turbulence}, volume = {986}, year = {2025}, }
• (2025). Deformation and differential rotation in slowly rotating young intermediate-mass stars. ApJ, 986(2), 227. (www)

  @article{ , abstract = {Asteroseismology, the study of stellar vibrations, is a method that can probe the structure deformation and internal rotation of stars. Salient among the seismic inferences of rotation from TESS observations are TIC 408165734, whose equatorial rotation rate is 10% faster than the pole, and TIC 307930890, which has significant radial shear and shows a decreasing spin rate outward through its envelope. We also measure structural deformation in 15 stars, nine of which are oblate, a finding consistent with expectations for relatively fast-rotating nonmagnetic stars. The difference between polar and equatorial radii in TIC 47639058 is 130 times larger than that for the Sun. The remaining six stars display splittings consistent with a prolate shape (surprisingly), possibly indicating the presence of equatorial toroidal magnetic fields. These inferences provide constraints for numerical simulations and new insights to guide theories of δ Scuti structure and rotation.}, archive = {J_ApJ}, author = {Subrata Kumar Panda and Shravan Hanasoge}, doi = {10.3847/1538-4357/add927}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {227}, shortjournal = {The Astrophys. J.}, title = {Deformation and differential rotation in slowly rotating young intermediate-mass stars}, volume = {986}, year = {2025}, }
• (2025). On the broadening of the characteristic frequency range toward higher photon energies in the X-ray variability of the black hole transient MAXI j1820+070. ApJ, 986(2), 226. (www)

  @article{ , abstract = {Energy-dependent X-ray power spectral states and band-limited noise (BLN) components have been seen in the low-hard state and intermediate states of black hole X-ray binaries. Here we report our analysis of Insight-HXMT observations of the black hole transient MAXI J1820+070 during its 2018 outburst when the source was brightest. We found opposite trends of low-frequency (<0.1 Hz) and high-frequency (>10 Hz) BLN components, i.e., decreasing versus increasing in frequency with increasing photon energy, respectively. This establishes an apparent two-way broadening of the power spectral plateau formed by multiple BLNs toward higher photon energies. The trend of the highest BLN component with increasing photon energy has been interpreted as indicating that the corresponding seed photons originated from a region relatively more central in the corona previously. The decreasing trend of the characteristic frequency of the lowest-frequency BLN component with increasing photon energy can then be interpreted as indicating that the corresponding seed photons originated from further out in the disk but on the opposite side of the central corona to the observer. These opposite trends then imply that the power spectral plateau represents the radial extension of the accretion disk that contributed the seed photons producing the BLNs, and show that the higher the photon energy is, the wider the plateau and the smaller the fractional variability. The plateau shows the analogy to the flat power spectrum with a low fractional variability of the power-law noise seen in the high-soft state, which corresponds to photons from the entire X-ray disk.}, archive = {J_ApJ}, author = {ChenXu Gao and Wenfei Yu and Zhen Yan}, doi = {10.3847/1538-4357/adda37}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {226}, shortjournal = {The Astrophys. J.}, title = {On the broadening of the characteristic frequency range toward higher photon energies in the X-ray variability of the black hole transient MAXI j1820+070}, volume = {986}, year = {2025}, }
• (2025). A new framework for interstellar medium emission line models: Connecting multiscale simulations across cosmological volumes. ApJ, 986(2), 225. (www)

  @article{ , abstract = {The James Webb Space Telescope (JWST) and Atacama Large Millimeter/submillimeter Array have detected emission lines from the ionized interstellar medium (ISM) in some of the first galaxies at z ≳ 6. These measurements present an opportunity to better understand galaxy assembly histories and may allow important tests of state-of-the-art galaxy formation simulations. It is challenging, however, to model these lines in their proper cosmological context. In order to meet this challenge, we introduce a novel subgrid line emission modeling framework. The framework uses the high- z zoom-in simulation suite from the Feedback in Realistic Environments (FIRE) collaboration. The line emission signals from H ii regions within each simulated FIRE galaxy are modeled using the semianalytic HIIL ines code. A machine learning approach is then used to determine the conditional probability distribution for the line luminosity to stellar-mass ratio from the H ii regions around each simulated stellar particle. This conditional probability distribution can then be applied to predict the line luminosities around stellar particles in lower-resolution, yet larger volume cosmological simulations. As an example, we apply this approach to the IllustrisTNG simulations at z = 6. The resulting predictions for the [O ii ], [O iii ], and Balmer line luminosities as a function of star formation rate agree well with current observations. Our predictions differ, however, from related works in the literature, which lack detailed subgrid ISM models. This highlights the importance of our multiscale simulation modeling framework. Finally, we provide forecasts for future line luminosity function measurements from the JWST and quantify the cosmic variance in such surveys.}, archive = {J_ApJ}, author = {Shengqi Yang and Adam Lidz and Andrew Benson and Yizhou Zhao and Hui Li and Amelia Zhao and Aaron Smith and Yucheng Zhang and Rachel Somerville and Anthony Pullen}, doi = {10.3847/1538-4357/addb41}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {225}, shortjournal = {The Astrophys. J.}, title = {A new framework for interstellar medium emission line models: Connecting multiscale simulations across cosmological volumes}, volume = {986}, year = {2025}, }
• (2025). The narrow formation pathway of hot saturns: Constraints on initial planetary properties. ApJ, 986(2), 224. (www)

  @article{ , abstract = {The observed exoplanet population exhibits a scarcity of short-period Saturn-mass planets, a phenomenon referred to as the "hot-Saturn desert." This observational scarcity can be utilized to validate the theories regarding the formation and evolution of gas planets. In this study, we conduct large-scale numerical simulations to explore how the initial conditions of gas planets orbiting solar-type and M-dwarf stars influence their evolutionary trajectories in the semimajor axis versus planetary radius ( a – R ) parameter space. We generate a synthetic population of 10,000 short-period gaseous planets by systematically varying their initial planetary masses ( M p ), initial planetary luminosities ( L p ), initial core mass fractions ( {f}_{{\rm{core}}} ), and semimajor axes ( a ). Furthermore, we assume these gaseous planets have ceased orbital migration and model their long-term thermal evolution, taking into account the impacts of atmospheric evaporation. Our results show that the initial M p , L p , and {f}_{{\rm{core}}} are the dominant factors controlling radius evolution for short-period gas planets. The key to survival as a hot-Saturn analog appears to be having just the right combination of properties after gas disk dissipation: an M p below 0.5 Jupiter mass ( M Jup ), a substantial {f}_{{\rm{core}}} of ≥30%, and relatively low L p on the order of 10 −6 solar luminosity ( L ⊙ ) or less. The survival criteria for hot-Saturn analogs align with theoretically unfavorable initial conditions of gas planets formed via core accretion scenario, naturally explaining the observed boundaries of the hot-Saturn desert.}, archive = {J_ApJ}, author = {Minghao Xie and Sheng Jin and Dong-Hong Wu}, doi = {10.3847/1538-4357/adddb3}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {224}, shortjournal = {The Astrophys. J.}, title = {The narrow formation pathway of hot saturns: Constraints on initial planetary properties}, volume = {986}, year = {2025}, }
• (2025). An analytical model of reconnection rate in electron-only reconnection. ApJ, 986(2), 223. (www)

  @article{ , abstract = {Modeling the reconnection rate of collisionless electron-only reconnection presents a theoretical challenge. Unlike traditional magnetic reconnection with ion coupling, electron-only reconnection has a higher reconnection rate due to the magnetic flux being frozen in the electron flow, which is constrained by the electron-Alfvénic velocity rather than the ion-Alfvénic velocity. Recent observations have revealed that the electron-only reconnection rate is about 0.23, which is at the high end of the theoretical range, and the electron flow velocity in the outflow region falls significantly below the electron-Alfvénic velocity. Based on MHD and gyrokinetic theory, we propose a steady-state analytical model to calculate the reconnection rate in electron-only reconnection. Our model demonstrates that the electric field generated in the outflow direction by the decoupling between ions and electrons in the outflow region plays a crucial role in suppressing electron-only reconnection. The plasma beta value negatively affects the reconnection rate in electron-only reconnection, i.e., the larger the plasma beta, the smaller the reconnection rate. The analytical results of our model align well with the reconnection rates reported in previous studies.}, archive = {J_ApJ}, author = {H. W. Zhan and S. Y. Huang and Q. Y. Xiong and Z. G. Yuan and K. Jiang and Z. Wang and Y. T. Tang}, doi = {10.3847/1538-4357/addece}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {223}, shortjournal = {The Astrophys. J.}, title = {An analytical model of reconnection rate in electron-only reconnection}, volume = {986}, year = {2025}, }
• (2025). A systematic search for X-ray eclipse events in active galactic nuclei observed by swift. ApJ, 986(2), 222. (www)

  @article{ , abstract = {The nuclear regions of active galactic nuclei (AGNs) likely host clumpy clouds that occasionally obscure the central X-ray source, causing eclipse events. These events offer a unique opportunity to study the properties and origins of such clouds. However, these transient events are rarely reported due to the need for extensive, long-term X-ray monitoring for years. Here, we conduct a systematic search for eclipse events in 40 AGNs well monitored by the Swift X-ray Telescope over the past 20 yr, comprising a total of ∼11,000 observations. Our selection criteria rely on significant variations in X-ray flux and spectral shape. We identify three high-confidence events in three AGNs and eight candidates in six AGNs, all in Type I AGNs. The observed clouds have column densities of N H ∼ (0.2–31.2) × 10 22 cm −2 and ionization degrees of log ξ ∼ (−1.3–2.2). For the five events with well-constrained duration, their distances from the central black hole range from (2.4 to 179) × 10 4 R g , with two clouds near the dust sublimation zone, two farther out. Interestingly, we find tentative correlations between the cloud properties (i.e., ionization state and column density) and the black hole mass and mass-accretion rate, implying their strong connection to the accretion process, potentially via outflows. Our study also demonstrates the potential of the new X-ray all-sky monitor, the Einstein Probe, in providing more detection and physical constraints for such events.}, archive = {J_ApJ}, author = {Tianying Lian and Chichuan Jin and Weimin Yuan}, doi = {10.3847/1538-4357/adcc15}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {222}, shortjournal = {The Astrophys. J.}, title = {A systematic search for X-ray eclipse events in active galactic nuclei observed by swift}, volume = {986}, year = {2025}, }
• (2025). Temporal properties of compressible magnetohydrodynamic turbulence. ApJ, 986(2), 221. (www)

  @article{ , abstract = {Describing the temporal properties of compressible magnetohydrodynamic (MHD) turbulence is a fundamental problem that has important implications for particle acceleration and transport in astrophysical plasmas. Here, by carefully analyzing the spatial and temporal properties of compressible MHD turbulence, we derive a new spectral power density function that is supported by simulations. This new function reveals that the low-frequency fluctuations are dominated by modes with small parallel wavenumbers with respect to the mean background magnetic field. Furthermore, for fluctuations with dynamically significant parallel wavenumbers, broadening around their eigenfrequencies is described by this function, which is in close agreement with simulations. We use this formalism to present the scaling properties of individual MHD modes. Such broadening is a direct consequence of nonlinear processes and is different for the three fundamental MHD modes. Our results provide a new window to investigate the temporal properties of turbulence and will enable further studies on the interaction between compressible MHD turbulence and energetic plasmas.}, archive = {J_ApJ}, author = {Ka Ho Yuen and Hui Li and Huirong Yan}, doi = {10.3847/1538-4357/add3ee}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {221}, shortjournal = {The Astrophys. J.}, title = {Temporal properties of compressible magnetohydrodynamic turbulence}, volume = {986}, year = {2025}, }
• (2025). N-body simulations of the self-confinement of viscous self-gravitating narrow eccentric planetary ringlets. ApJ, 986(2), 220. (www)

  @article{ , abstract = {Narrow eccentric planetary ringlets have sharp edges, sizable eccentricity gradients, and a confinement mechanism that prevents radial spreading due to ring viscosity. Most proposed ringlet confinement mechanisms presume that there is one or more shepherd satellites whose gravitational perturbations keep the ringlet confined radially, but the absence of such shepherds in Cassini observations of Saturn's rings casts doubt upon those ringlet confinement mechanisms. The following uses a suite of N -body simulations to explore an alternate scenario, whereby ringlet self-gravity drives a narrow eccentric ringlet into a self-confining state. These simulations show that, under a wide variety of initial conditions, an eccentric ringlet's secular perturbations of itself causes the eccentricity of its outer edge to grow at the expense of its inner edge. This causes the ringlet's nonlinearity parameter q to grow over time until it exceeds the q\simeq \sqrt{3}/2 threshold where the ringlet's orbit-averaged angular momentum flux due to viscosity + self-gravity is zero. The absence of any net radial angular momentum transfer through the ringlet means that the ringlet has settled into a self-confining state, i.e . , it does not spread radially due to its viscosity, and simulations also show that such ringlets have sharp edges. Nonetheless, viscosity still circularizes the ringlet in time τ e ∼ 10 6 orbits ∼1000 yr, which will cause the ringlet's nonlinearity parameter to shrink below the q\simeq \sqrt{3}/2 threshold and allows radial spreading to resume. Either sharp-edged narrow eccentric ringlets are transient phenomena or exterior perturbations are also sustaining the ringlet's eccentricity. We then speculate about how such ringlets might come to be.}, archive = {J_ApJ}, author = {Joseph M. Hahn and Douglas P. Hamilton and Thomas Rimlinger and Yuxi(Lucy) Lu}, doi = {10.3847/1538-4357/add3f5}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {220}, shortjournal = {The Astrophys. J.}, title = {N-body simulations of the self-confinement of viscous self-gravitating narrow eccentric planetary ringlets}, volume = {986}, year = {2025}, }
• (2025). Formation of a possible black-hole ultracompact X-ray binary with the shortest orbital period. ApJ, 986(2), 219. (www)

  @article{ , abstract = {In the bulge of M31, the Chandra observations discovered a possible black hole (BH) ultracompact X-ray binary (UCXB) Seq.1 with an orbital period of 7.7 minutes and a maximum X-ray luminosity {L}_{{\rm{X}}}=1.0{9}_{-0.01}^{+0.02}\,\times 1{0}^{38}\,{\rm{erg}}\,{{\rm{s}}}^{-1} in the 0.5–8 keV band. The minimum orbital period of the BH UCXBs predicted by the standard magnetic braking (MB) model is longer than 8.3 minutes. In this work, we investigate whether the convection- and rotation-boosted (CARB) MB prescription can account for the formation of a BH UCXB such as Seq.1. Our detailed stellar evolution models indicate that the CARB MB law can drive isolated BH–main-sequence (MS) binaries to evolve toward BH UCXBs with an orbital period of 7.7 minutes, in which a low-mass white dwarf transfers the material onto a BH in a short-term mass-transfer episode, producing an X-ray luminosity of ∼10 38 erg s −1 . We also obtain an initial parameter space of BH–MS binaries as the progenitors of Seq.1 in the donor-star masses and orbital periods plane, which can be applied to future population synthesis simulations. If Seq.1 is indeed a BH UCXB, future spaceborne gravitational wave (GW) detectors can detect the low-frequency GW signals from this source, and a tidal disruption event will be expected after 0.12 Myr.}, archive = {J_ApJ}, author = {Xing-Peng Yang and Kun Xu and Zhi-Fu Gao and Long Jiang and Wen-Cong Chen}, doi = {10.3847/1538-4357/add479}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {219}, shortjournal = {The Astrophys. J.}, title = {Formation of a possible black-hole ultracompact X-ray binary with the shortest orbital period}, volume = {986}, year = {2025}, }
• (2025). Luminosity and stellar mass functions of faint photometric satellites around spectroscopic central galaxies from DESI year-1 bright galaxy survey. ApJ, 986(2), 218. (www)

  @article{ , abstract = {We measure the luminosity functions (LFs) and stellar mass functions (SMFs) of photometric satellite galaxies around spectroscopically identified isolated central galaxies (ICGs). The photometric satellites are from the DESI Legacy Imaging Surveys (DR9), while the spectroscopic ICGs are selected from the DESI Year-1 BGS sample. We can measure satellite LFs down to r -band absolute magnitudes of M r ,sat ∼ −7, around ICGs as small as 7.1\lt {{\rm{log}}}_{10}{M}_{\ast ,{\rm{ICG}}}/{M}_{\odot }\lt 7.8 , with the stellar mass of ICGs measured by the DESI F astspecfit pipeline. The satellite SMF can be measured down to {{\rm{log}}}_{10}{M}_{\ast ,{\rm{sat}}}/{M}_{\odot }\sim 5.5 . Interestingly, we discover that the faint/low-mass end slopes of satellite LFs/SMFs become steeper with the decrease in the stellar masses of host ICGs, with smaller and nearby host ICGs capable of being used to probe their fainter satellites. The steepest slopes can be −2.298 ± 0.656 and −2.888 ± 0.916 for satellite LF and SMF, respectively. Detailed comparisons are performed between the satellite LFs around ICGs selected from DESI BGS or from the SDSS NYU-VAGC spectroscopic Main galaxies over 7.1\lt {{\rm{log}}}_{10}{M}_{\ast ,{\rm{ICG}}}/{M}_{\odot }\lt 11.7 , showing reasonable agreement, but we show that differences between DESI and SDSS stellar masses for ICGs play a role to affect the results. We also compare measurements based on DESI F astspecfit and C igale stellar masses used to bin ICGs, with the latter including the modeling of active galactic nuclei based on Wide-field Infrared Survey Explorer photometry, and we find good agreements in the measured satellite LFs by using either of the DESI stellar mass catalogs.}, archive = {J_ApJ}, author = {Wenting Wang and Xiaohu Yang and Yipeng Jing and Ashley J. Ross and Malgorzata Siudek and John Moustakas and Samuel G. Moore and Shaun Cole and Carlos Frenk and Jiaxi Yu and Sergey E. Koposov and Jiaxin Han and Zhenlin Tan and Kun Xu and Yizhou Gu and Yirong Wang and Oleg Y. Gnedin and Jessica Nicole Aguilar and Steven Ahlen and Davide Bianchi and David Brooks and Todd Claybaugh and Axel de la Macorra and Arjun Dey and Peter Doel and Jaime E. Forero-Romero and Enrique Gaztañaga and Satya Gontcho A Gontcho and Gaston Gutierrez and Klaus Honscheid and Mustapha Ishak and Theodore Kisner and Martin Landriau and Laurent Le Guillou and Marc Manera and Aaron Meisner and Ramon Miquel and Seshadri Nadathur and Claire Poppett and Francisco Prada and Ignasi Pérez-Ràfols and Graziano Rossi and Eusebio Sanchez and David Schlegel and Hee-Jong Seo and Joseph Harry Silber and David Sprayberry and Gregory Tarlé and Benjamin Alan Weaver and Hu Zou}, doi = {10.3847/1538-4357/add5df}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {218}, shortjournal = {The Astrophys. J.}, title = {Luminosity and stellar mass functions of faint photometric satellites around spectroscopic central galaxies from DESI year-1 bright galaxy survey}, volume = {986}, year = {2025}, }
• (2025). Improving porosity calculation methods and proposing a new model universally applicable to large- and medium-sized planetary objects. ApJ, 986(2), 217. (www)

  @article{ , abstract = {Our work was aimed at the improvement of two main already existing methods of porosity calculation on a planetary scale in order to expand these methods to be applicable to exoplanetary interiors. In addition to implementing some improvements in the used approach, we also wanted to provide a new, more sophisticated model with the combination of the two base models. Utilizing our combined model we aimed to provide results regarding the porosity structure of the interior of four planetary bodies of the solar system (Enceladus, Earth, Mars, and the Moon), chosen as case studies. Taking a method that is based on fitted functions to experimental data from geological environments, and a separate method based on the temporal evolution of planetary interiors governed by thermodynamic processes, we developed a combined model, which incorporates the advantages of both base models. The proposed new model produced a pore compaction depth of 62.52 km for the core of Enceladus, 4.5 km for Earth, 19.96 km for Mars, and 32.51 km for the Moon. Moreover, we have discovered differing trends between the effect of changes in geothermal gradient and surface temperatures across planetary objects of different sizes.}, archive = {J_ApJ}, author = {Imre Kisvárdai and Ákos Kereszturi}, doi = {10.3847/1538-4357/add723}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {217}, shortjournal = {The Astrophys. J.}, title = {Improving porosity calculation methods and proposing a new model universally applicable to large- and medium-sized planetary objects}, volume = {986}, year = {2025}, }
• (2025). Estimating global ejecta mass ratios in tycho’s supernova remnant. ApJ, 986(2), 216. (www)

  @article{ , abstract = {In this work, as a follow-up to our similar analysis of Kepler's supernova remnant (SNR), we estimate total mass ratios of various ejecta elements in Tycho's SNR using Suzaku X-ray data. In our spectral analysis, we account for uncertainties arising from Suzaku's effective area calibration (5%–15%) and from the unknown filling factors of the various plasma components in our spectral model (1%–10%). We compare our calculated ejecta mass ratios to results from previous X-ray analyses of Tycho's SNR and to the nucleosynthesis results from Type Ia supernova simulations. Our estimated ejecta mass ratios for Tycho's SNR are only consistent with simulations that use a ∼90% attenuated 12 C+ 16 O reaction rate (as for Kepler's SNR), are inconsistent with simulations involving a double detonation of a thick helium layer, and support a Type Ia explosion of normal luminosity where ∼85% of the ejecta has been heated by the reverse shock.}, archive = {J_ApJ}, author = {Tyler Holland-Ashford and Patrick Slane and Brian Williams}, doi = {10.3847/1538-4357/add7d4}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {216}, shortjournal = {The Astrophys. J.}, title = {Estimating global ejecta mass ratios in tycho’s supernova remnant}, volume = {986}, year = {2025}, }
• (2025). Shadow-based framework for estimating transition disk geometries. ApJ, 986(2), 215. (www)

  @article{ , abstract = {Some transition disks host misaligned inner disks with radii of several astronomical units. Understanding the geometric and physical properties of these misaligned disks is essential for advancing terrestrial planet formation models. This study introduces a novel method to infer the three-dimensional structures of both inner and outer disks by analyzing nonaxisymmetric shadows and the horizon in optical and infrared scattered light images of the outer disk. This method was applied to the HD 100453 system, in which infrared scattered light images from the Very Large Telescope revealed disk shadows. These results indicate that the inner disk is misaligned by ∼70° relative to the outer disk, which is consistent with the results of previous studies. The aspect ratio of the inner disk surface was estimated to be 0.17, which may reflect the surface height of the optically thick dusty component due to vertical lofting by MHD winds or turbulence. In addition, the surface height distribution of the outer disk was characterized, providing novel insights into its vertical structure.}, archive = {J_ApJ}, author = {Ryuta Orihara and Munetake Momose}, doi = {10.3847/1538-4357/add890}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {215}, shortjournal = {The Astrophys. J.}, title = {Shadow-based framework for estimating transition disk geometries}, volume = {986}, year = {2025}, }
• (2025). Understanding stellar Mass–Metallicity and size relations in simulated ultrafaint dwarf galaxies. ApJ, 986(2), 214. (www)

  @article{ , abstract = {Reproducing the physical characteristics of ultrafaint dwarf galaxies (UFDs) in cosmological simulations is challenging, particularly with respect to stellar metallicity and galaxy size. To investigate these difficulties in detail, we conduct high-resolution simulations ( M gas ∼ 60 M ⊙ , M DM ∼ 300 M ⊙ ) on six UFD analogs ( M vir ∼ 10 8 –10 9 M ⊙ , M ⋆ ∼ 10 3 –2.1 × 10 4 M ⊙ at z = 0). Our findings reveal that the stellar properties of the UFD analogs are shaped by diverse star-forming environments from multiple progenitor halos in the early Universe. Notably, our UFD analogs exhibit a better match to the observed mass–metallicity relation, showing higher average metallicity compared to other theoretical models, though our results remain 0.5–1 dex lower than for observed UFDs. The metallicity distribution functions (MDFs) of our simulated UFDs lack high-metallicity stars ([Fe/H]≥ −2.0) while containing low-metallicity stars ([Fe/H] < −4.0). Excluding these low-metallicity stars, our results align well with the MDFs of observed UFDs. However, forming stars with higher metallicity (−2.0 ≤ [Fe/H] max ≤ −1.5) remains a challenge, due to the difficulty of sustaining metal enrichment during the brief star formation period before cosmic reionization. Additionally, our simulations show extended outer structures in UFDs, similar to recent Milky Way UFD observations, resulting from dry mergers between progenitor halos. To ensure consistency, we adopt the same fitting method commonly used in observations to derive the half-light radius. We find that this method tends to produce lower values compared to direct calculations and struggles to accurately describe the extended outer structures.}, archive = {J_ApJ}, author = {Minsung Go and Myoungwon Jeon and Yumi Choi and Nitya Kallivayalil and Sangmo Tony Sohn and Gurtina Besla and Hannah Richstein and Sal Wanying Fu and Tae Bong Jeong and Jihye Shin}, doi = {10.3847/1538-4357/add2fa}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {214}, shortjournal = {The Astrophys. J.}, title = {Understanding stellar Mass–Metallicity and size relations in simulated ultrafaint dwarf galaxies}, volume = {986}, year = {2025}, }
• (2025). On acceleration of highest-energy cosmic rays in a novel scenario of magnetar transients. ApJ, 986(2), 213. (www)

  @article{ , abstract = {Transient phenomena in magnetars have been considered as possible acceleration sites of ultra-high-energy cosmic rays (CRs), whose energy reaches ∼200 EeV, such as the Amaterasu particle. However, the process of CR acceleration and the trigger mechanism of magnetar transients remain unclear. A recently suggested scenario for the activity predicts that the magnetar's rotation axis suddenly flips due to the "Dzhanibekov effect," resulting in a sudden rise of the Euler force. The material in the outer layer plastically flows due to the force and finally fractures in this scenario. We study the possibilities of ion acceleration along with this scenario. If the degenerate electrons burst open from the fractured region like a balloon burst, the pair plasma formation can be ignited inside the crust. We find that such pair plasma can emit photons similar to the observed bursts from magnetars. We also find that the electron stream at the beginning of the burst phenomenon possibly induces a strong electric field for a moment, resulting in the acceleration of ∼1 ZeV ion within a timescale of ∼1 ps. The nuclear spallation reactions limit this timescale, and therefore, high-energy CR "neutrons" from the parenteral nuclei become proper observational predictions of this scenario: their arrival time and direction will be correlated with the bursting photon emissions of the host magnetars. The nuclear spallation of ∼1 ZeV nuclei is preferred to explain ≳10 PeV neutrino events observed by IceCube and KM3Net.}, archive = {J_ApJ}, author = {Jiro Shimoda and Tomoki Wada}, doi = {10.3847/1538-4357/add33c}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {213}, shortjournal = {The Astrophys. J.}, title = {On acceleration of highest-energy cosmic rays in a novel scenario of magnetar transients}, volume = {986}, year = {2025}, }
• (2025). Spatially resolved Galaxy–Dust modeling with coupled data-driven priors. ApJ, 986(2), 212. (www)

  @article{ , abstract = {A notorious problem in astronomy is the recovery of the true shape and spectral energy distribution (SED) of a galaxy despite attenuation by interstellar dust embedded in the same galaxy. This problem has been solved for a few hundred nearby galaxies with exquisite data coverage, but these techniques are not scalable to the billions of galaxies soon to be observed by large wide-field surveys like the Legacy Survey of Space and Time, Euclid, and Roman. We present a method for jointly modeling the spatially resolved stellar and dust properties of galaxies from multiband images. To capture the diverse geometries of galaxies, we consider nonparametric morphologies, stabilized by two neural networks that act as data-driven priors: the first informs our inference of the galaxy's underlying morphology, while the second constrains the galaxy's dust morphology conditioned on our current estimate of the galaxy morphology. We demonstrate with realistic simulations of z ∼ 0 galaxies that we can recover galaxy host and dust properties over a wide range of attenuation levels and geometries. We apply our joint galaxy–dust model to three local galaxies observed by the Sloan Digital Sky Survey and find qualitatively good results. In addition to improving estimates of unattenuated galaxy SEDs, our inferred dust maps will facilitate the study of dust production, transport, and destruction. However, without informed priors on the inferred host spectrum, our method is vulnerable to the thin-screen limit; future work will need to address this degeneracy with stellar population synthesis modeling.}, archive = {J_ApJ}, author = {Jared C. Siegel and Peter Melchior}, doi = {10.3847/1538-4357/add3f9}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {212}, shortjournal = {The Astrophys. J.}, title = {Spatially resolved Galaxy–Dust modeling with coupled data-driven priors}, volume = {986}, year = {2025}, }
• (2025). Generation of large-scale magnetic fields upstream of gamma-ray burst afterglow shocks. ApJ, 986(2), 211. (www)

  @article{ , abstract = {The origins of the magnetic fields that power gamma-ray burst (GRB) afterglow emission are not fully understood. One possible channel for generating these fields involves the pre-conditioning of the circumburst medium: in the early afterglow phase, prompt photons streaming ahead of the GRB external shock can pair produce, seeding the upstream with drifting electron–positron pairs and triggering electromagnetic microinstabilities. To study this process, we employ 2D periodic particle-in-cell simulations in which a cold electron–proton plasma is gradually enriched with warm electron–positron pairs injected at mildly relativistic speeds. We find that continuous pair injection drives the growth of large-scale magnetic fields via filamentation-like instabilities; the temporal evolution of the field is self-similar and depends on a single parameter, {\left[\alpha /({t}_{{\rm{f}}}{\omega }_{{\rm{pi}}})\right]}^{1/2}t{\omega }_{{\rm{pi}}} , where α is the ratio of final pair beam density to background plasma density, t f is the duration of pair injection, and ω pi is the plasma frequency of background protons. Extrapolating our results to parameter regimes realistic for long GRBs, we find that upstream pair enrichment generates weak magnetic fields on scales much larger than the proton skin depth; for bright bursts, the extrapolated coherence scale at a shock radius of R ∼ 10 17 cm is \left\langle {\lambda }_{y}\right\rangle \,\sim 100\ c/{\omega }_{{\rm{pi}}} , and the corresponding magnetization is σ ∼ 10 −8 for typical circumburst parameters. These results may help explain the persistence of magnetic fields at large distances behind GRB shocks.}, archive = {J_ApJ}, author = {Ryan Golant and Arno Vanthieghem and Daniel Grošelj and Lorenzo Sironi}, doi = {10.3847/1538-4357/add404}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {211}, shortjournal = {The Astrophys. J.}, title = {Generation of large-scale magnetic fields upstream of gamma-ray burst afterglow shocks}, volume = {986}, year = {2025}, }
• (2025). X-ray polarization in SN 1006 southwest shows spatial variations and differences in the radio band. ApJ, 986(2), 210. (www)

  @article{ , abstract = {We report the detection of a spatial variation of X-ray polarization in the southwestern (SW) shell of supernova remnant SN 1006 (SN 1006 SW) using the Imaging X-ray Polarimetry Explorer (IXPE). The shell has an average X-ray polarization degree (PD) of 21.6% ± 4.5% and polarization angle of −48 ∘ ± 5 ∘ in the 2–4 keV energy band, similar to those in the northeastern shell. The PD varies along SN 1006 SW, with a peak PD = 40% ± 8% in the south and a significantly lower PD ≲ 27% (99% upper limit) in the west, where the shell has been proposed to be interacting with an interstellar cloud. The correlation between the PD, which reflects the magnetic orderliness, and the preshock density provides observational evidence that magnetic turbulence and amplification are environment-dependent. The high PD detected in the southern region of the shell constrains the magnetic turbulence scale to ≲0.1 pc. Moreover, by comparing the IXPE X-ray and MeerKAT radio polarization measurements for SN 1006 SW, we found that magnetic fields traced by X-ray polarization are nearly radially distributed, whereas those traced by radio polarization tend to follow a direction parallel to the Galactic plane. This suggests that the X-ray polarization probes freshly amplified magnetic fields from small-scale structures in the immediate postshock region, while the radio traces more extended regions influenced by the preexisting ambient magnetic fields.}, archive = {J_ApJ}, author = {Ping Zhou and Patrick Slane and Dmitry Prokhorov and Jacco Vink and Riccardo Ferrazzoli and William Cotton and Niccolò Bucciantini and Yi-Jung Yang and Stefano Silvestri and Douglas A. Swartz and Philip Kaaret and Enrico Costa and C.-Y. Ng and Estela Reynoso and Paolo Soffitta and Allyn F. Tennant and Wenlang He and David Moffett}, doi = {10.3847/1538-4357/add532}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {210}, shortjournal = {The Astrophys. J.}, title = {X-ray polarization in SN 1006 southwest shows spatial variations and differences in the radio band}, volume = {986}, year = {2025}, }
• (2025). Parker solar probe observations of a highly energetic and asymmetric reconnecting heliospheric current sheet during encounter 13. ApJ, 986(2), 209. (www)

  @article{ , abstract = {We report Parker Solar Probe observations of reconnection during an unusual heliospheric current sheet (HCS) crossing at 14.8 solar radii that occurred ∼15 hr after the passage of a CME. The HCS was surrounded by unusually low solar wind density. The hybrid Alfvén speed ( V A ∼ 515 km s −1 ) and available magnetic energy per particle ( m i V A 2 ∼ 3 keV) were the highest observed to date surrounding an HCS. Inside the HCS, the peak outflow speed (∼525 km s −1 ) and proton and electron bulk heating, at ∼400 eV and ∼25 eV, respectively, were also the highest observed to date associated with HCS reconnection. Unusual for an HCS, the density on the two sides of the HCS differed by a factor of ∼13. Consequently, the spatial plasma profiles across the HCS resembled those of planetary magnetopauses, with the fastest outflow occurring near the low-density edge of the HCS. A striking feature of this HCS is the asymmetric nature of the superthermal protons escaping the HCS along separatrix field lines. On the low solar wind density side, the low-velocity cutoff of escaping protons was substantially higher than on the high-density side. The cutoffs were close to the bulk outflow speeds measured near the two edges of the asymmetric HCS, suggesting that only particles faster than the outflow speeds can escape the HCS. Electrons were also energized and leaked out of the HCS, forming a layer of field-aligned superthermal electrons. These escaping electrons are distinguishable from solar strahl electrons observed further away from the HCS, which had lower energies.}, archive = {J_ApJ}, author = {T. D. Phan and O. M. Romeo and J. F. Drake and D. Larson and M. Øieroset and S. Eriksson and B. Lavraud and S. D. Bale and A. Rahmati and R. Livi and P. Whittlesey and M. Pulupa and J. Huang and J. Halekas and M. L. Stevens and A. Szabo and N. Raouafi}, doi = {10.3847/1538-4357/add534}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {209}, shortjournal = {The Astrophys. J.}, title = {Parker solar probe observations of a highly energetic and asymmetric reconnecting heliospheric current sheet during encounter 13}, volume = {986}, year = {2025}, }
• (2025). Intermediate mass ratio inspirals in milky way galaxies. ApJ, 986(2), 208. (www)

  @article{ , abstract = {A consequence of a nonzero occupation fraction of massive black holes (MBHs) in dwarf galaxies is that these MBHs can become residents of larger galaxy halos via hierarchical merging and tidal stripping. Depending on the parameters of their orbits and original hosts, some of these MBHs will merge with the central supermassive black hole in the larger galaxy. We examine four cosmological zoom-in simulations of Milky Way-like galaxies to study the demographics of the black hole mergers that originate from dwarf galaxies. Approximately half of these mergers have mass ratios less than 0.04, which we categorize as intermediate mass ratio inspirals, or IMRIs. Inspiral durations range from 0.5–8 Gyr, depending on the compactness of the dwarf galaxy. Approximately half of the inspirals may become more circular with time, while the eccentricity of the remainder does not evolve. Overall, IMRIs in Milky Way-like galaxies are a significant class of black hole mergers that can be detected by LISA, and must be prioritized for waveform modeling.}, archive = {J_ApJ}, author = {Jillian Bellovary and Yuantong Luo and Thomas R. Quinn and Ferah Munshi and Michael Tremmel and James Wadsley}, doi = {10.3847/1538-4357/add9a0}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {208}, shortjournal = {The Astrophys. J.}, title = {Intermediate mass ratio inspirals in milky way galaxies}, volume = {986}, year = {2025}, }
• (2025). X-ray polarization study of the neutron star low-mass X-ray binary GX 349+2. ApJ, 986(2), 207. (www)

  @article{ , abstract = {We report the first X-ray polarimetric results of the neutron star (NS) low-mass X-ray binary Z-source GX 349+2 using the Imaging X-ray Polarimetry Explorer (IXPE). We discovered that the X-ray source was polarized at a polarization degree of PD = 1.1% ± 0.3% (1 σ errors) with a polarization angle of PA = 32° ± 6° (1 σ errors). Simultaneous Nuclear Spectroscopic Telescope Array observations show that the source transitioned through the normal branch, flaring branch, and soft apex of the Z-track during our IXPE observations. The X-ray spectropolarimetry results suggest a source geometry comprising an accretion disk component, a blackbody representing the emission from the NS surface, and a Comptonized component. We discuss the accretion geometry of the Z-source in light of the spectropolarimetric results.}, archive = {J_ApJ}, author = {Unnati Kashyap and Thomas J. Maccarone and Mason Ng and Eliot C. Pattie and Swati Ravi and Herman L. Marshall}, doi = {10.3847/1538-4357/adda35}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {207}, shortjournal = {The Astrophys. J.}, title = {X-ray polarization study of the neutron star low-mass X-ray binary GX 349+2}, volume = {986}, year = {2025}, }
• (2025). Modern earth-like chemical disequilibrium biosignatures are challenging to constrain through spectroscopic retrievals. ApJ, 986(2), 206. (www)

  @article{ , abstract = {Robust exoplanet characterization studies are underway, and the community is looking ahead toward developing observational strategies to search for life beyond our solar system. With the development of life detection approaches like searching for atmospheric chemical species indicative of life, chemical disequilibrium has also been proposed as a potentially key signature for life. Chemical disequilibrium can arise from the production of waste gases due to biological processes and can be quantified using a metric known as the available Gibbs free energy. The main goal of this study was to explore the detectability of chemical disequilibrium for a modern Earth-like analog. Atmospheric retrievals coupled to a thermodynamics model were used to determine posterior distributions for the available Gibbs free energy given simulated observations at various noise levels. In reflected light, chemical disequilibrium signals were difficult to detect and limited by the constraints on the CH 4 abundance, which was challenging to constrain for a modern Earth case with simulated observations spanning ultraviolet through near-infrared wavelengths with V band signal-to-noise ratios of 10, 20, and 40. For a modern Earth analog orbiting a late-type M dwarf, we simulated transit observations with the James Webb Space Telescope Mid-Infrared Instrument and found that tight constraints on the available Gibbs free energy can be achieved, but only at extremely low noise on the order of several parts per million. This study serves as further proof of concept for remotely inferring chemical disequilibrium biosignatures and should be included in continuing to build life detection strategies for future exoplanet characterization missions.}, archive = {J_ApJ}, author = {Amber V. Young and Tyler D. Robinson and Joshua Krissansen-Totton and Edward W. Schwieterman and Giada Arney and Gerrick E. Lindberg and Cristina Thomas}, doi = {10.3847/1538-4357/addbd7}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {206}, shortjournal = {The Astrophys. J.}, title = {Modern earth-like chemical disequilibrium biosignatures are challenging to constrain through spectroscopic retrievals}, volume = {986}, year = {2025}, }
• (2025). Formation of h+ PUI tails downstream of distant interplanetary shocks. ApJ, 986(2), 205. (www)

  @article{ , abstract = {New Horizons' Solar Wind Around Pluto (SWAP) instrument has observed interplanetary shocks from ∼20 to 60 au from the Sun. Different studies have analyzed the effects of these shocks on the solar wind ion (SWI) and interstellar pickup ion (PUI) distributions. A key finding includes the observation of PUI tails downstream of some shocks. However, PUI tails have only been observed when SWAP was measuring 24 hr averages of the count rate histograms. After a software change in 2021 February, SWAP's measurement resolution was improved to ∼30 minutes averages, but no PUI tails have been observed since this change. In this study, we use a test particle code to simulate the downstream SWI and PUI distributions to study the possible existence and formation of PUI tails, using the shock compression ratio, shock thickness, and turbulence as free parameters. We find that in most cases, a suprathermal tail does not develop downstream of interplanetary shocks, but a persistent hump and PUI cutoff exists at energies above the PUI injection energy. The extent of the hump largely depends on the shock compression ratio. We find PUI tails do form when turbulence is included in the model. After we convert our distributions to count rates in the spacecraft frame, the results show similar structure to the data. We conclude that significant H + PUI tails can form downstream of distant interplanetary shocks if there is a relatively large compression ratio (>2) and significant turbulence present.}, archive = {J_ApJ}, author = {E. J. Zirnstein and D. J. McComas and B. L. Shrestha and H. A. Elliott and P. C. Brandt and S. A. Stern and A. R. Poppe and J. Parker and E. Provornikova and K. Singer and A. Verbiscer and New Horizons Heliophysics Team}, doi = {10.3847/1538-4357/addf45}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {205}, shortjournal = {The Astrophys. J.}, title = {Formation of h+ PUI tails downstream of distant interplanetary shocks}, volume = {986}, year = {2025}, }
• (2025). Clouds can enhance direct-imaging detection of o2 and o3 on terrestrial exoplanets. ApJ, 986(2), 204. (www)

  @article{ , abstract = {Clouds are often considered a highly uncertain barrier for detecting biosignatures on exoplanets, especially given intuition gained from transit surveys. However, for direct-imaging reflected light observations, clouds could increase the observational signal by increasing reflected light. Here we constrain the impact of clouds on the detection of O 2 and O 3 by a direct-imaging telescope such as the Habitable Worlds Observatory (HWO) using observations simulated with the Planetary Spectrum Generator (PSG). We first perform sensitivity tests to show that low clouds enhance O 2 and O 3 detectability while high clouds diminish it, and the effect is greater when cloud particles are smaller. We next apply clouds produced by the cloud microphysics model Community Aerosol and Radiation Model for Atmospheres with varied planetary parameters and clouds drawn from observations of different types of clouds on Earth to PSG. We find that clouds are likely to increase the signal-to-noise ratio of O 2 and O 3 for terrestrial exoplanets under a wide range of scenarios. This work provides important constraints on the impact of clouds on observations by telescopes including HWO.}, archive = {J_ApJ}, author = {Huanzhou Yang and Michelle Hu and Dorian S. Abbot}, doi = {10.3847/1538-4357/add46b}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {204}, shortjournal = {The Astrophys. J.}, title = {Clouds can enhance direct-imaging detection of o2 and o3 on terrestrial exoplanets}, volume = {986}, year = {2025}, }
• (2025). Linear response of rotating and flattened stellar clusters: The oblate Kuzmin–Kutuzov stäckel family. ApJ, 986(2), 203. (www)

  @article{ , abstract = {This paper investigates the linear response of a series of spheroidal stellar clusters, the Kuzmin–Kutuzov Stäackel family, which exhibit a continuous range of flattening and rotation, extending from an isochrone sphere to a Toomre disk. The method successfully replicates the growing modes previously identified in published N -body simulations. It relies on the efficiency of the matrix method to quantify systematically the effects of rotation and flattening on the eigenmodes of the galaxy. We identify two types of bisymmetric instabilities for the flatter models—the so-called bending and bar-growing modes—the latter of which persists even for very round models. As anticipated, in its least unstable configurations, the system becomes flatter as its rotational speed increases. More realistic equilibria will be required to achieve a better match to the main sequence of fast–slow rotators. The corresponding code is made public.}, archive = {J_ApJ}, author = {Kerwann Tep and Christophe Pichon and Michael S. Petersen}, doi = {10.3847/1538-4357/add5e5}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {203}, shortjournal = {The Astrophys. J.}, title = {Linear response of rotating and flattened stellar clusters: The oblate Kuzmin–Kutuzov stäckel family}, volume = {986}, year = {2025}, }
• (2025). Results from an Einstein@Home search for continuous gravitational waves from cassiopeia a and vela jr. using LIGO o2 data. ApJ, 986(2), 202. (www)

  @article{ , abstract = {We conduct two searches for continuous, nearly monochromatic gravitational waves originating from the central compact objects in the supernova remnants Cassiopeia A (Cas A) and Vela Jr. using public LIGO data. The search for Cas A targets signal frequencies between 20 Hz and 400 Hz, and the Vela Jr. search covers between 400 and 1700 Hz. They both investigate the broadest set of waveforms ever considered with highly sensitive deterministic search methods. Above 1500 Hz, the Vela Jr. search is the most sensitive carried out thus far, improving on previous results by over 300%. Above 976 Hz these results improve on existing ones by 50%. In all, we investigate over 10 18 waveforms, leveraging the computational power donated by thousands of Einstein@Home volunteers. We perform a four-stage follow-up on more than 6 million waveforms. None of the considered waveforms survives the follow-up scrutiny, indicating no significant detection candidate. Our null results constrain the maximum amplitude of continuous signals as a function of signal frequency from the targets. The most stringent 90% confidence upper limit for Cas A is {h}_{0}^{90 \% }\approx 7.3\times 1{0}^{-26} near 200 Hz, and for Vela Jr. it is {h}_{0}^{90 \% }\approx 8.9\times 1{0}^{-26} near 400 Hz. Translated into upper limits on the ellipticity and r- mode amplitude, our results probe physically interesting regions: for example, the ellipticity of Vela Jr. is constrained to be smaller than 10 −7 across the frequency band, with a tighter constraint of less than 2 × 10 −8 at the highest frequencies.}, archive = {J_ApJ}, author = {Jorge Morales and Jing Ming and Maria Alessandra Papa and Heinz-Bernd Eggenstein and Bernd Machenschalk}, doi = {10.3847/1538-4357/add5f5}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {202}, shortjournal = {The Astrophys. J.}, title = {Results from an Einstein@Home search for continuous gravitational waves from cassiopeia a and vela jr. using LIGO o2 data}, volume = {986}, year = {2025}, }
• (2025). Describing the nonuniversal galaxy merger timescales in IllustrisTNG: Effects of host halo mass, baryons, and sample selection. ApJ, 986(2), 201. (www)

  @article{ , abstract = {Galaxy merger timescales are crucial for understanding and modeling galaxy formation in our hierarchically structured Universe. However, previous studies have reported widely varying dependencies of merger timescales on initial orbital parameters and mass ratios at the first crossing of r vir . Using IllustrisTNG simulations, we find that these dependencies vary with host halo mass, suggesting that discrepancies in prior studies may arise from differences in the systems analyzed. Specifically, in low-mass halos, merger timescales show a stronger dependence on initial orbital parameters, while, in high-mass halos, this dependence weakens. To account for these variations, we present a fitting formula that incorporates host mass dependence, achieving a logarithmic scatter smaller than 0.15 dex. Comparing dark-matter-only and baryonic simulations, we observe similar merger timescales for circular orbits but notable differences for radial orbits. In halos with M host < 10 12.5 h −1 M ⊙ , mergers in dark-matter-only runs take longer than in baryonic runs, whereas the trend reverses in more massive halos. We attribute these differences to the competing effects of tidal disruption by central galaxy disks and the resistance of baryonic satellites to tidal stripping. Finally, we extend our model to predict merger timescales from any starting radius within the halo. By fitting the extended model to the entire infall sample, we find that using only the merger sample can underestimate merger timescales, particularly for low mass ratios. Our model provides a valuable tool for improving semianalytical and empirical models of galaxy formation.}, archive = {J_ApJ}, author = {Kun Xu and Y. P. Jing}, doi = {10.3847/1538-4357/add5f6}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {201}, shortjournal = {The Astrophys. J.}, title = {Describing the nonuniversal galaxy merger timescales in IllustrisTNG: Effects of host halo mass, baryons, and sample selection}, volume = {986}, year = {2025}, }
• (2025). Detection of hydrocarbons in the disk around an actively accreting planetary-mass object. ApJ, 986(2), 200. (www)

  @article{ , abstract = {We present the 0.6–12 μ m spectrum of Cha 1107-7626, a 6–10 Jupiter-mass free-floating object in the ∼2 Myr-old Chamaeleon-I star-forming region, from observations with the NIRSpec and MIRI instruments on board the James Webb Space Telescope. We confirm that Cha 1107-7626 is one of the lowest-mass objects known to harbor a dusty disk with infrared excess emission at wavelengths beyond 4 μ m. Our NIRSpec data and prior ground-based observations provide strong evidence for ongoing accretion through hydrogen recombination lines. In the mid-infrared spectrum, we detect unambiguously emission lines caused by methane (CH 4 ) and ethylene (C 2 H 4 ) in its circumsubstellar disk. Our findings mean that Cha 1107-7626 is by far the lowest-mass object with hydrocarbons observed in its disk. The spectrum of the disk looks remarkably similar to that of ISO-ChaI 147, a very low-mass star with a carbon-rich disk that is 10–20 times more massive than Cha 1107-7626. The hydrocarbon lines can be accounted for with a model assuming gas temperatures of a few hundred kelvin in the inner disk. The obvious similarities between the spectra of a low-mass star and a planetary-mass object indicate that the conditions in the inner disks can be similar across a wide range of central object masses.}, archive = {J_ApJ}, author = {Laura Flagg and Aleks Scholz and V. Almendros-Abad and Ray Jayawardhana and Belinda Damian and Koraljka Mužić and Antonella Natta and Paola Pinilla and Leonardo Testi}, doi = {10.3847/1538-4357/add71d}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {200}, shortjournal = {The Astrophys. J.}, title = {Detection of hydrocarbons in the disk around an actively accreting planetary-mass object}, volume = {986}, year = {2025}, }
• (2025). Quantifying the impact of the dust torque on the migration of low-mass planets. II. the role of pebble accretion in planet growth within a global planet formation model. ApJ, 986(2), 199. (www)

  @article{ , abstract = {Although dust constitutes only about 1% of the mass in a protoplanetary disk, recent studies reveal its substantial impact on the torques experienced by low- and intermediate-mass planetary cores. In this study, we present the first comprehensive analysis of the dust torque's influence on the evolution of growing planetary embryos as they migrate through a protoplanetary disk and undergo gas and pebble accretion. Our global model incorporates viscous accretion and X-ray photoevaporation effects on the gaseous disk while also accounting for the dynamic processes of dust growth and evolution, including coagulation, drift, and fragmentation. Our findings demonstrate that dust torque significantly affects planetary migration patterns, particularly facilitating prominent outward migration for planets forming within the water-ice line. This outward thrust arises from an enhanced dust-to-gas mass ratio in the inner disk, driven by the inward drift of pebbles from the outer regions. Conversely, for planets that originate beyond the water-ice line, while the dust torque attenuates inward migration, it does not substantially alter their overall migration trajectories. This is attributed to the rapid reduction in dust-to-gas mass ratio, resulting from swift pebble drift and the short formation timescales prevalent in that region. Overall, our findings highlight the critical role of dust torque in shaping the migration of low- and intermediate-mass planets, particularly in conditions where increased dust concentrations amplify its effects. These insights have significant implications for understanding the formation timescales, mass distributions, and compositional characteristics of emerging planetary systems.}, archive = {J_ApJ}, author = {Octavio M. Guilera and Pablo Benitez-Llambay and Marcelo M. Miller Bertolami and Martin E. Pessah}, doi = {10.3847/1538-4357/add92a}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {199}, shortjournal = {The Astrophys. J.}, title = {Quantifying the impact of the dust torque on the migration of low-mass planets. II. the role of pebble accretion in planet growth within a global planet formation model}, volume = {986}, year = {2025}, }
• (2025). Analysis of jet dynamics and collimation characteristics of 0241+622 on parsec scales. ApJ, 986(2), 198. (www)

  @article{ , abstract = {We conducted a detailed analysis of the jet structure and dynamics of the source 0241+622 on milliarcsecond scales. We stacked images from multiple epochs to better recover the cross section of the jet. By analyzing the relationship between jet width and distance, we observed that the jet exhibits a parabolic shape from the core, spanning a region from 0.12 to 6.1 mas. This structure suggests the acceleration and collimation processes of the jet. Beyond 18 mas from the core, the jet adopts a conical shape, and the expansion speed of the jet becomes faster within the range from 4500 to 6500 mas. We obtained the core shift of this source using five pairs of data from the Very Long Baseline Array at 1.6 to 43 GHz. Based on previous studies, through proper motion analysis of the jet components, we estimated the angle between the jet and the line of sight to be approximately 65 \mathop{.}\limits^{\unicode{x000b0}} 7, so 1 mas corresponds to 0.95 pc (deprojected distance). We then obtained the velocity field of the source within 3.14 mas from the central black hole and found that the jet exhibits accelerated motion within this range. At approximately 6.1 mas from the core, we observed that the jet width begins to decrease, which we identified as possibly corresponding to the Bondi radius of this source. The reduction in jet width may be related to changes in the external environmental pressure, particularly within the Bondi radius, indicating that the jet dynamics and collimation characteristics are strongly influenced by the surrounding medium conditions.}, archive = {J_ApJ}, author = {Haitian Shang and Wei Zhao and Xiaoyu Hong and Xu-zhi Hu}, doi = {10.3847/1538-4357/addd10}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {198}, shortjournal = {The Astrophys. J.}, title = {Analysis of jet dynamics and collimation characteristics of 0241+622 on parsec scales}, volume = {986}, year = {2025}, }
• (2025). Oscillatory magnetic reconnection at a coronal bright point. ApJ, 986(2), 197. (www)

  @article{ , abstract = {Coronal bright points (CBPs) are typical small-scale coronal brightenings that consist of a bundle of miniature coronal loops. Using the ultrahigh-resolution coronal images from the Extreme Ultraviolet Imager on board Solar Orbiter, we report the first observational evidence of oscillatory magnetic reconnection at a CBP. The reconnection is characterized by two bursty phases defined by a reconnection reversal. In the first phase, a current sheet (C1) was found to form in front of an expanding loop of the bright point. Interestingly, C1 shortened to a null point during 10 minutes after reaching its maximum length (∼2.4 Mm). Less than 3 minutes later, a new current sheet (C2) was clearly seen to grow out from the null point, but along an orthogonal direction relative to C1. C2 reached a maximum length of ∼4 Mm in 10 minutes and then became short and invisible in the next few minutes as the reconnection declined. The magnetic reconnection is evidenced by the brightening, plasma flow, and temperature increase at the ends of both C1 and C2. No significant magnetic cancellation or emergence but gradual convergence occurred during the few hours before the reconnection underneath the CBP. The transition from C1 to C2 suggests the occurrence of coronal oscillatory reconnection, whereby the inflow and outflow regions in the first phase become the outflow and inflow regions in the second phase, respectively. It is further found that the oscillatory reconnection could slightly modulate the change in brightness of the CBP. We propose that oscillatory reconnection has the potential to continuously heat solar small-scale structures without destroying their overall magnetic configurations.}, archive = {J_ApJ}, author = {Junchao Hong and Jiayan Yang and Yi Bi and Bo Yang}, doi = {10.3847/1538-4357/addda9}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {197}, shortjournal = {The Astrophys. J.}, title = {Oscillatory magnetic reconnection at a coronal bright point}, volume = {986}, year = {2025}, }
• (2025). Intermediate-mass-ratio inspirals with general dynamical friction in dark matter minispikes. ApJ, 986(2), 196. (www)

  @article{ , abstract = {Intermediate-mass-ratio inspirals (IMRIs) may be surrounded by dark matter (DM) minispikes. The dynamical friction from these DM minispike structures can affect the dynamics and the gravitational-wave (GW) emission of the IMRIs. We analyze the effects of general dynamical friction, with a particular contribution from DM particles moving faster than the stellar-mass black hole in an eccentric IMRI. Our calculations show that these DM particles tend to increase the eccentricity of the orbit; therefore, the evolution of the eccentricity depends on the competition between the fast-moving DM particles and the slow-moving DM particles. The results show that the dynamical friction enhances the eccentricity when γ sp ≲ 2.0, and the general dynamical friction is able to increase the eccentricity. We also analyze the effects of general dynamical friction on the GW characteristic strain. The results indicate that the characteristic strain is suppressed at lower frequencies, and the peak value of the characteristic strain occurs at higher frequencies as the power-law index of the DM minispike γ sp increases. For the first time, a relation between the frequency peak value of the characteristic strain of GWs and γ sp is established. Using this analytical relation, the presence of DM and its halo density may potentially be determined from future GW data.}, archive = {J_ApJ}, author = {Yu-Chen Zhou and Hong-Bo Jin and Cong-Feng Qiao and Yue-Liang Wu}, doi = {10.3847/1538-4357/adddbc}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {196}, shortjournal = {The Astrophys. J.}, title = {Intermediate-mass-ratio inspirals with general dynamical friction in dark matter minispikes}, volume = {986}, year = {2025}, }
• (2025). The MBH–M∗ relation of the hyperluminous dust-obscured quasars up to z ∼ 4. ApJ, 986(2), 195. (www)

  @article{ , abstract = {Hot dust-obscured galaxies (Hot DOGs) are a rare population of hyperluminous dust-obscured quasars discovered by the Wide-field Infrared Survey Explorer (WISE) all-sky survey. The heavy circumnuclear dust obscuration allows only a small amount of scattered light from the obscured quasar to escape, enabling the decomposition of the stellar component from the total flux. The presence of scattered light enables the redshift of the source and the properties of the black hole to be obtained from the Sloan Digital Sky Survey (SDSS) and SDSS-related literature. From WISE and SDSS data, we select 11 hyperluminous Hot DOGs at z = 1.5–3.7 with bolometric luminosities L bol ≳ 10 47 erg s −1 . We investigate the M BH – M ⋆ relation in these sources using Bayesian spectral energy distribution fitting or with extra constraints from Hubble Space Telescope image decomposition. Stellar masses are successfully derived for eight Hot DOGs. We find high Eddington ratios λ Edd in these Hot DOGs, with the median value of 1.05 and the maximum value close to 3. The super-Eddington accretion may be associated with the overdense environments of Hot DOGs. We find no significant differences in the M BH / M ⋆ of these Hot DOGs compared to the local relation, suggesting that these dust-obscured quasars are the progenitors of massive early-type galaxies. We speculate that the subsequent evolution of Hot DOGs may be significantly influenced by active galactic nucleus feedback and remain on the local relation.}, archive = {J_ApJ}, author = {Yibin Luo and Lulu Fan and Weibin Sun and Haoran Yu and Yunkun Han and Guangwen Chen and Mengqiu Huang and Yihang Zhang and Zheyu Lin}, doi = {10.3847/1538-4357/addecf}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {195}, shortjournal = {The Astrophys. J.}, title = {The MBH–M∗ relation of the hyperluminous dust-obscured quasars up to z ∼ 4}, volume = {986}, year = {2025}, }
• (2025). VLA FRAMEx. II. radio spectra of nearby active galactic nuclei at subarcsecond resolution. ApJ, 986(2), 194. (www)

  @article{ , abstract = {We present 4–12 GHz in-band spectral energy distributions with accompanying 6 GHz and 10 GHz imaging results for a volume-complete sample (<40 Mpc) of hard X-ray selected active galactic nuclei observed with the Karl G. Jansky Very Large Array (VLA) in its A-array configuration. Despite expectations, only 12 out of 25 of these targets have been detected by the Very Long Baseline Array (VLBA) at milliarcsecond resolution in our previous studies, and we aim to understand why the circumnuclear radio emission resolves away at the subparsec spatial scales. We find that the sources not detected by the VLBA are also the faintest sources observed with the VLA. We explore the spectral structure derived from the nuclear emission and measure a mean spectral index of 〈 α 〉 = −0.69 with a scatter of σ α = 0.18 for the sources not detected by the VLBA, indicative of optically thin synchrotron emission. The 12 sources detected by the VLBA primarily have flat (−0.5 ≤ α ≤ 0.0) or inverted ( α > 0) spectral indices. Nine of the sources have statistically significant curvature, with only one that was not detected by the VLBA. In NGC 3079, we model an approximately flat spectrum for the excess emission observed by the VLA that is likely produced entirely beyond parsec spatial scales.}, archive = {J_ApJ}, author = {Andrew J. Sargent and Alexander J. van der Horst and Megan C. Johnson and Travis C. Fischer and Nathan J. Secrest and Phil J. Cigan and Onic I. Shuvo and Krista L. Smith}, doi = {10.3847/1538-4357/adc5fe}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {194}, shortjournal = {The Astrophys. J.}, title = {VLA FRAMEx. II. radio spectra of nearby active galactic nuclei at subarcsecond resolution}, volume = {986}, year = {2025}, }
• (2025). Impact of the cosmic web on the properties of galaxies in IllustrisTNG simulations. ApJ, 986(2), 193. (www)

  @article{ , abstract = {We investigate the influence of the cosmic web on galaxy properties in the IllustrisTNG simulations. To disentangle the effects of galaxy groups and cosmic filaments, we divide the cosmic web environment into four categories: group, group-dominated region, filament-dominated region, and field. By controlling for stellar mass, we reveal evident differences in specific star formation rates (sSFRs), quenched fraction, gas fractions, local density, and stellar ages among central galaxies in different cosmic web environments, particularly for lower-mass galaxies. However, these differences largely diminish when the effect of local overdensity is further accounted for, indicating its dominant role. Additionally, we observe distinct differences in these properties among satellite galaxies across environments, mainly driven by stellar mass, halo mass, and overdensity. Notably, residual differences between satellites in field and filament-dominated regions persist even after controlling for these factors, suggesting a stronger susceptibility of satellite galaxies to filaments compared to central galaxies. Our findings highlight the importance of differentiating between central and satellite to accurately assess the environmental effects of the cosmic web. Our analysis suggests that the relationship between galaxy properties and their distance from filaments arises from a combination of factors, including stellar and halo mass, groups, overdensity, and the intrinsic influence of the cosmic web. Additionally, we find that the effect of the cosmic web on galaxy properties is reduced at z = 0.5, compared to z = 0. Furthermore, central galaxies near thick filaments tend to exhibit slightly to moderately lower sSFR and cold gas fractions compared to those near thin filaments.}, archive = {J_ApJ}, author = {Guangyao Yu and Weishan Zhu and Qi-Rui Yang and Jian-Feng Mo and Tian-Cheng Luan and Long-Long Feng}, doi = {10.3847/1538-4357/adc80f}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {193}, shortjournal = {The Astrophys. J.}, title = {Impact of the cosmic web on the properties of galaxies in IllustrisTNG simulations}, volume = {986}, year = {2025}, }
• (2025). MG1-1995959: An eclipsing binary star with a pronounced O’Connell effect. ApJ, 986(2), 192. (www)

  @article{ , abstract = {MG1-1995959 is a short-period (∼0.586 day) eclipsing binary, exhibiting at times an extraordinarily large O'Connell effect (OE), for which this paper reports its discovery, time series photometry, and spectroscopic observation. The photometry is scattered across years 2001–2023, with spectroscopic observations from 2023. Photometric curves exhibit classical OE asymmetries, whereby maxima following primary and secondary eclipses are of different magnitudes. Short time span photometric time series provide static characterizations of OE stars yielding incomplete representations of critical macrobehavior. In contrast, MG1-1995959 photometry is of sufficient duration to indicate pronounced changes in such behavior, suggesting that intense observing programs can provide key benchmark data to better inform complex modeling efforts. Spectra indicate the primary to be K1 Vk(e), and the secondary type is ∼K5 V. PHOEBE modeling of the light curve from 2014 enables estimation of key stellar parameters (primary/secondary): T eff [K] (5110/4260), and, in solar units, mass (0.86/0.68) and radius (0.93/0.65). The inclination of the system was found to be ∼78°. PHOEBE modeling of light curves from 2013, 2022, and 2023 is presented, demonstrating (1) the light curves can be well fit by invoking distributions of star spots, (2) optimal spot sizes and distributions vary dramatically as a function of time, and (3) this is a powerful tool with which to investigate the short term evolution of this star. MG1-1995959 is an accessible star with dynamic and unusual behavior deserving of intensive study to better understand nuances of the OE and the nature of late-type main-sequence stars.}, archive = {J_ApJ}, author = {Eric R. Craine and Brian L. Craine and Christopher J. Corbally and Adam L. Kraus and Andy S. Kulessa and Roger B. Culver and Grady Boyce and Tim B. Hunter and W. Marwood and Mike Miller and Geoffrey C. Stone}, doi = {10.3847/1538-4357/add013}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {192}, shortjournal = {The Astrophys. J.}, title = {MG1-1995959: An eclipsing binary star with a pronounced O’Connell effect}, volume = {986}, year = {2025}, }
• (2025). The NANOGrav 12.5 yr data set: Probing interstellar turbulence and precision pulsar timing with PSR j1903+0327. ApJ, 986(2), 191. (www)

  @article{ , abstract = {Free electrons in the interstellar medium refract and diffract radio waves along multiple paths, resulting in angular and temporal broadening of radio pulses that limits pulsar timing precision. We determine multifrequency, multiepoch scattering times for the large dispersion measure millisecond PSR J1903+0327 by developing a three-component model for the emitted pulse shape that is convolved with a best-fit pulse broadening function (PBF) identified from a family of thin-screen and extended-media PBFs. We show that the scattering time, τ , at a fiducial frequency of 1500 MHz changes by approximately 10% over a 5.5 yr span with a characteristic timescale of approximately 100 days. We also constrain the spectral index and inner scale of the wavenumber spectrum of electron density variations along this line of sight. We find that the scaling law for τ versus radio frequency is strongly affected by any mismatch between the true and assumed PBF or between the true and assumed intrinsic pulse shape. We show using simulations that refraction is a plausible cause of the epoch dependence of τ , manifesting as changes in the PBF shape and 1/ e timescale. Finally, we discuss the implications of our scattering results on pulsar timing including time of arrival delays and dispersion measure misestimation.}, archive = {J_ApJ}, author = {Abra Geiger and James M. Cordes and Michael T. Lam and Stella Koch Ocker and Shami Chatterjee and Zaven Arzoumanian and Ava L. Battaglia and Harsha Blumer and Paul R. Brook and Olivia A. Combs and H. Thankful Cromartie and Megan E. DeCesar and Paul B. Demorest and Timothy Dolch and Justin A. Ellis and Robert D. Ferdman and Elizabeth C. Ferrara and Emmanuel Fonseca and Nate Garver-Daniels and Peter A. Gentile and Deborah C. Good and Megan L. Jones and Duncan R. Lorimer and Jing Luo and Ryan S. Lynch and Maura A. McLaughlin and Cherry Ng and David J. Nice and Timothy T. Pennucci and Nihan S. Pol and Scott M. Ransom and Renée Spiewak and Ingrid H. Stairs and Kevin Stovall and Joseph K. Swiggum and Sarah J. Vigeland}, doi = {10.3847/1538-4357/add0b6}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {191}, shortjournal = {The Astrophys. J.}, title = {The NANOGrav 12.5 yr data set: Probing interstellar turbulence and precision pulsar timing with PSR j1903+0327}, volume = {986}, year = {2025}, }
• (2025). Spatially resolved circumgalactic medium around a star-forming galaxy driving a galactic outflow at z ≈ 0.8. ApJ, 986(2), 190. (www)

  @article{ , abstract = {We report the small-scale spatial variation in cool ( T ∼ 10 4 K) Mg ii absorption detected in the circumgalactic medium (CGM) of a star-forming galaxy at z ≈ 0.8. The CGM of this galaxy is probed by a spatially extended bright background gravitationally lensed arc at z = 2.76. The background arc continuously samples the CGM of the foreground galaxy at a range of impact parameters between 54 and 66 kpc. The Mg ii absorption strengths vary by more than a factor of 2 within these ranges. A power-law fit to the fractional variation of absorption strengths yields a coherence length of 5.8 kpc within this range of impact parameters. This suggests a high degree of spatial coherence in the CGM of this galaxy. The host galaxy is driving a strong galactic outflow with a mean outflow velocity ≈ −179 km s −1 and mass outflow rate {\dot{M}}_{\mathrm{out}}\,\geqslant \,6{4}_{-27}^{+31} M ⊙ yr −1 traced by blueshifted Mg ii and Fe ii absorption lines. The galaxy itself has a spatially extended emission halo with a maximum spatial extent of ≈33 kpc traced by [O ii ], [O iii ], and H β emission lines. The extended emission halo shows kinematic signatures of corotating halo gas with solar metallicity. Taken together, these observations suggest evidence of a baryon cycle that is recycling the outflowing gas to form the next generation of stars.}, archive = {J_ApJ}, author = {Ahmed Shaban and Rongmon Bordoloi and John M. O’Meara and Keren Sharon and Nicolas Tejos and Sebastian Lopez and Cédric Ledoux and L. Felipe Barrientos and Jane R. Rigby}, doi = {10.3847/1538-4357/add0b9}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {190}, shortjournal = {The Astrophys. J.}, title = {Spatially resolved circumgalactic medium around a star-forming galaxy driving a galactic outflow at z ≈ 0.8}, volume = {986}, year = {2025}, }
• (2025). Evidence for GeV gamma-ray emission from intense GRB 240529A during the afterglow’s shallow decay phase. ApJ, 986(2), 189. (www)

  @article{ , abstract = {X-ray light curves of gamma-ray burst (GRB) afterglows exhibit various features, with the shallow decay phase being particularly puzzling. While some studies report the absence of the X-ray shallow decay for hyperenergetic GRBs, recently discovered GRB 240529A shows a clear shallow decay phase with an isotropic gamma-ray energy of 2.2 × 10 54 erg, making it a highly unusual case compared to typical GRBs. In order to investigate the physical mechanism of the shallow decay, we perform the Fermi-Large Area Telescope (LAT) analysis of GRB 240529A along with the Swift-X-Ray Telescope analysis. We find no jet break feature in the X-ray light curve and then give the lower bound of the collimation-corrected jet energy of >10 52 erg, which is close to the maximum rotational energy of a magnetar. Our LAT data analysis reveals evidence of GeV emission with a statistical significance of 4.5 σ during the shallow decay phase, which can be interpreted as the first case for hyperenergetic GRBs with a typical shallow decay phase. The GeV to keV flux ratio is calculated to be 4.2 ± 2.3. Together with the X-ray spectral index, this indicates an inverse Compton origin of the GeV emission. Multiwavelength modeling based on time-dependent simulations tested two promising models, the energy injection and wind models. Both models can explain the X-ray and gamma-ray data, while our modeling demonstrates that gamma-ray observations, along with future GeV–TeV observations by the Cherenkov Telescope Array Observatory, will distinguish between them.}, archive = {J_ApJ}, author = {Kenta Terauchi and Tomohiko Oka and Katsuaki Asano}, doi = {10.3847/1538-4357/add113}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {189}, shortjournal = {The Astrophys. J.}, title = {Evidence for GeV gamma-ray emission from intense GRB 240529A during the afterglow’s shallow decay phase}, volume = {986}, year = {2025}, }
• (2025). Accretion and recovery in giant eruptions of massive stars. ApJ, 986(2), 188. (www)

  @article{ , abstract = {Giant eruptions are episodic high-rate mass-loss events that massive stars experience in the late-stage of their evolution before exploding as a core-collapse supernova. If a giant eruption occurs in a binary system, the companion star can accrete part of the mass. We use numerical simulations to analyze how the companion responds to accretion and how its structure and evolution are altered. We run a grid of massive stars with masses from 20 M ⊙ to 60 M ⊙ , and accretion rates from 10 −4 to 0.1 M ⊙ yr −1 , over a duration of 20 yr. For accretion rates ≲0.01 M ⊙ yr −1 , the star remains on the hotter side of the HR diagram with a minor increase in luminosity without expanding because the accretion timescale exceeds the thermal time scale by a larger factor. Mass loss through stellar winds leads to a minor drop in luminosity shortly after the accretion phase as the star enters the recovery phase. For ≳0.01 M ⊙ yr −1 , the companion star experiences a sudden increase in luminosity by about one order of magnitude, inflates, and cools. Under the accreted gas layer, the star retains its structure and continues to eject radiation-driven wind during the recovery phase, namely the time it takes to regain equilibrium. Eventually, the accreted material mixes with the inner layers of the star and the star continues to evolve as a more massive star.}, archive = {J_ApJ}, author = {Bhawna Mukhija and Amit Kashi}, doi = {10.3847/1538-4357/add3f1}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {188}, shortjournal = {The Astrophys. J.}, title = {Accretion and recovery in giant eruptions of massive stars}, volume = {986}, year = {2025}, }
• (2025). Out on a limb: The signatures of East–West asymmetries in transmission spectra from general circulation models. ApJ, 986(2), 187. (www)

  @article{ , abstract = {In the era of JWST, observations of hot Jupiter atmospheres are becoming increasingly precise. As a result, the signatures of limb asymmetries due to temperature or abundance differences and the presence of aerosols can now be directly measured using transmission spectroscopy. Using a grid of general circulation models with varying irradiation temperatures (1500–4000 K) and prescriptions of cloud formation, we simulate 3D ingress/egress and morning-/evening-limb transmission spectra. We aim to assess the impact that clouds, 3D temperature structure, and nonuniform distribution of gases have on the observed spectra, and how these inhomogeneities can be identified. A second goal is to assess the relative merits of two separate methods (ingress/egress versus morning-/evening-limb spectroscopy) for isolating atmospheric asymmetries. From our models, it is evident that an east–west temperature difference is the leading-order effect for producing ingress/egress or morning-/evening-limb spectral differences. We additionally find that clouds contribute strongly to the observed limb asymmetry at moderate irradiation temperatures in our grid (∼2000 K < T irr < 3500 K). At lower temperatures clouds equally dominate the optical depth on both limbs, while at higher temperatures the entire terminator region remains cloud free. We develop limb asymmetry metrics that can be used to assess the degree of east–west asymmetry for a given planet and predict trends in these metrics with respect to irradiation temperature that are indicative of various physical processes. Our results are useful for predicting and diagnosing the signatures of limb asymmetries in JWST spectra.}, archive = {J_ApJ}, author = {Kenneth E. Arnold and Arjun B. Savel and Eliza M.-R. Kempton and Michael T. Roman and Emily Rauscher and Isaac Malsky and Hayley Beltz and Maria E. Steinrueck}, doi = {10.3847/1538-4357/add3f6}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {187}, shortjournal = {The Astrophys. J.}, title = {Out on a limb: The signatures of East–West asymmetries in transmission spectra from general circulation models}, volume = {986}, year = {2025}, }
• (2025). X-ray radiative transfer calculation based on a physics-based model of the subparsec-scale gases around an active galactic nucleus and its application to NGC 3783. ApJ, 986(2), 186. (www)

  @article{ , abstract = {Although the X-ray spectra of Seyfert 1 galaxies exhibit absorption lines of He-like iron and H-like iron at blueshifted velocities of approximately 500 km s −1 , the physical origin of these absorption lines remains uncertain. In this study, we performed X-ray radiative transfer based on the subparsec-scale thermally driven outflows. The initial step involved calculating the photoionization equilibrium using the Cloudy code, which is based on three-dimensional radiative hydrodynamic simulations. Subsequently, X-ray radiative transfer was performed using the Monte Carlo Simulation for Astrophysics and Cosmology code. Our findings indicate that when the angle of inclination ranges within 55°–65°, the transmitted component of the X-ray spectrum displays absorption lines of He-like and H-like iron, exhibiting a blueshift of approximately 500 km s −1 . The results suggest that the absorption lines are generated by a photoionized gas within 0.005 pc. Additionally, the results indicate that the scattered component of the X-ray spectrum exhibits emission lines originating from neutral iron fluorescence, He-like iron, and H-like iron. The emission lines are broadened by approximately 7000 km s −1 due to the Keplerian rotation. Furthermore, the model reproduced the H-like iron and H-like iron absorption lines in NGC 3783 observed by the Chandra High Energy Transmission Grating.}, archive = {J_ApJ}, author = {Atsushi Tanimoto and Keiichi Wada and Hirokazu Odaka and Yuki Kudoh and Nozomu Kawakatu}, doi = {10.3847/1538-4357/add402}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {186}, shortjournal = {The Astrophys. J.}, title = {X-ray radiative transfer calculation based on a physics-based model of the subparsec-scale gases around an active galactic nucleus and its application to NGC 3783}, volume = {986}, year = {2025}, }
• (2025). Explaining nonmerger gamma-ray bursts and broad-lined supernovae with close binary progenitors with black hole central engines. ApJ, 986(2), 185. (www)

  @article{ , abstract = {For over 25 yr, the origin of long-duration gamma-ray bursts (lGRBs) has been linked to the collapse of rotating massive stars. However, we have yet to pinpoint the stellar progenitor powering these transients. Moreover, the dominant engine powering the explosions remains open to debate. Observations of both lGRBs, supernovae associated with these GRBs, such as broad-line (BL) stripped-envelope (type Ic) supernovae (hereafter, Ic-BL), supernovae (SNe), and perhaps superluminous SNe, fast blue optical transients, and fast x-ray transients, may provide clues to both engines and progenitors. In this paper, we conduct a detailed study of the tight-binary formation scenario for lGRBs, comparing this scenario to other leading progenitor models. Combining this progenitor scenario with different lGRB engines, we can compare to existing data and make predictions for future observational tests. We find that the combination of the tight-binary progenitor scenario with the black hole accretion disk engine can explain lGRBs, low-luminosity GRBs, ultra-long GRBs, and Ic-BL. We discuss the various progenitor properties required for these different subclasses and note such systems would be future gravitational-wave merger sources. We show that the current literature on other progenitor-engine scenarios cannot explain all of these transient classes with a single origin, motivating additional work. We find that the tight-binary progenitor with a magnetar engine is excluded by existing observations. The observations can be used to constrain the properties of stellar evolution, the nature of the GRB, and the associated SN engines in lGRBs and Ic-BL. We discuss the future observations needed to constrain our understanding of these rare, but powerful, explosions.}, archive = {J_ApJ}, author = {Christopher L. Fryer and Eric Burns and Anna Y. Q. Ho and Alessandra Corsi and Amy Y. Lien and Daniel A. Perley and Jada L. Vail and V. Ashley Villar}, doi = {10.3847/1538-4357/add474}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {185}, shortjournal = {The Astrophys. J.}, title = {Explaining nonmerger gamma-ray bursts and broad-lined supernovae with close binary progenitors with black hole central engines}, volume = {986}, year = {2025}, }
• (2025). Challenging the LyC–Lyα relation: Strong lyα emitters without LyC leakage at z ∼ 2.3. ApJ, 986(2), 184. (www)

  @article{ , abstract = {The escape fraction of Lyman continuum (LyC) ionizing radiation ( {f}_{{\rm{esc}}}^{{\rm{LyC}}} ) is crucial for understanding reionization, yet difficult to measure at z ≳ 4. Recently, studies have focused on calibrating indirect indicators of {f}_{{\rm{esc}}}^{{\rm{LyC}}} at z ∼ 0.3, finding that Ly α is closely linked to it. What is still unclear is whether the LyC–Ly α relation evolves with redshift, and if Ly α is truly applicable as an {f}_{{\rm{esc}}}^{{\rm{LyC}}} indicator during the Epoch of Reionization. In this study, we investigate seven −21 ≲ M UV ≲ −19 gravitationally lensed galaxies from the BOSS Emission-Line Lens Survey for GALaxy-Lyα EmitteR sYstems (or BELLS GALLERY) at z ∼ 2.3. Our targets have rest-frame Ly α equivalent widths between 40 Å and 200 Å and low dust content (−2.4 ≲ β ≲ −2.0), both indicative of high LyC escape. Surprisingly, direct estimates of {f}_{{\rm{esc}}}^{{\rm{LyC}}} using Hubble Space Telescope imaging with F275W and F225W reveal that our targets are not LyC emitters, with an absolute {f}_{{\rm{esc}}}^{{\rm{LyC}}} < 13% (assuming the median intergalactic medium transmission). The low {f}_{{\rm{esc}}}^{{\rm{LyC}}} , coupled with the high Ly α equivalent width and escape fraction, could potentially be attributed to the redshift evolution of the neutral hydrogen column density and dust content, as well as covering fractions of optically thick gas below 1 in high-redshift galaxies. Additionally, our analysis suggests that the emission for each lensed component is uniformly absorbed. Our results challenge the validity of the extrapolation of z ∼ 0 Ly α -based LyC indirect estimators into the Epoch of Reionization.}, archive = {J_ApJ}, author = {Annalisa Citro and Claudia M. Scarlata and Kameswara B. Mantha and Liliya R. Williams and Marc Rafelski and Mitchell Revalski and Matthew J. Hayes and Alaina Henry and Michael J. Rutkowski and Harry I. Teplitz and Andrea Grazian and Anahita Alavi}, doi = {10.3847/1538-4357/add5e6}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {184}, shortjournal = {The Astrophys. J.}, title = {Challenging the LyC–Lyα relation: Strong lyα emitters without LyC leakage at z ∼ 2.3}, volume = {986}, year = {2025}, }
• (2025). The spectra of solar magnetic energy and helicity. ApJ, 986(2), 183. (www)

  @article{ , abstract = {Previous studies have used magnetic energy and helicity spectra, the latter computed using the two-scale method, to search for signatures of mean-field dynamos. In this study, we compare cotemporal HMI and SOLIS synoptic vector magnetograms to illustrate the instrument-dependence of even qualitative features of the energy and helicity spectra. Around the minimum between solar cycles 24 and 25, we find that the magnetic energy spectrum computed from HMI observations exhibits two distinct peaks. One of these peaks is only present near the cycle minimum and corresponds to large-scale magnetic fields at high latitudes. Nevertheless, such magnetic fields are not present in contemporaneous synoptic vector magnetograms from SOLIS. Further, even when magnetograms from both instruments are apodized, the helicity spectra calculated using the two-scale method disagree (on both the sign and the value of the fractional helicity). This suggests that currently available synoptic magnetograms are not reliable enough for such studies.}, archive = {J_ApJ}, author = {G. Kishore and Nishant K. Singh}, doi = {10.3847/1538-4357/add692}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {183}, shortjournal = {The Astrophys. J.}, title = {The spectra of solar magnetic energy and helicity}, volume = {986}, year = {2025}, }
• (2025). X-ray polarization of the high-synchrotron-peaked BL lac h 1426+428. ApJ, 986(2), 182. (www)

  @article{ , abstract = {We report the X-ray polarization properties of the high-synchrotron-peaked BL Lac H 1426+428, based on two-epoch observational data from the Imaging X-ray Polarimetry Explorer (IXPE). For the first observation, only an upper limit of polarization degree (Π X ), Π X < 19.5%, at the 99% confidence level (CL) is determined. In contrast, for the second observation, we derive Π X = 20.6% ± 2.9% with a polarization angle ( ψ X ) of ψ X = 116 \mathop{.}\limits^{\unicode{x000b0}} 1 ± 4 \mathop{.}\limits^{\unicode{x000b0}} 1 at a CL of 7.1 σ . The time-resolved and energy-resolved polarization analysis reveals no significant variation in ψ X and no detectable polarization within narrower energy bins for the first observation, while the polarization during the second observation is dominated by low-energy photons. Furthermore, the X-rays during the second observation are found to be in a higher flux state with a harder spectrum compared to that observed during the first observation, consistent with a harder-when-brighter behavior. We propose that the enhanced X-ray emission observed during the second observation is produced by shock-accelerated electrons within an ordered magnetic field region via synchrotron radiation. Nonetheless, no significant detection of polarization during the first IXPE observation may be due to the limited number of detected photons.}, archive = {J_ApJ}, author = {Xin-Ke Hu and Jia-Xuan Li and Yu-Wei Yu and Ji-Shun Lian and Wei Deng and Hai-Ming Zhang and Jin Zhang}, doi = {10.3847/1538-4357/add87d}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {182}, shortjournal = {The Astrophys. J.}, title = {X-ray polarization of the high-synchrotron-peaked BL lac h 1426+428}, volume = {986}, year = {2025}, }
• (2025). Orbital phase-resolved analysis of X-ray and gamma-ray observations of the high-mass gamma-ray binary 4FGL j1405.1−6119. ApJ, 986(2), 181. (www)

  @article{ , abstract = {We present the results of multiwavelength observations of the high-mass gamma-ray binary (HMGB) 4FGL J1405.1−6119. A pair of joint XMM-Newton and NuSTAR observations taken in 2019 (sampling the gamma-ray maximum and X-ray maximum) characterize the emissiong of soft and hard X-rays. We find variability of the hydrogen column density along our line of sight, N H , and photon index, Γ, and find no evidence of pulsations in X-rays. We also refine a new best-fit orbital period to P = 13.7157 ± 0.0014 days, the first orbital phase-resolved analysis based on nearly 16 yr of Fermi-LAT observations of 4FGL J1405.1−6119 and the evolution of the spectral shape as a function of orbital phase. Finally, the X-ray and gamma-ray spectra for the phases sampled in the new X-ray observations can be interpreted in the framework of the intrabinary shock model, previously applied to HMGBs such as LS 5039.}, archive = {J_ApJ}, author = {Alexander Lange and Robin H.D. Corbet and Joel B. Coley and Guillaume Dubus and Jeremy Hare and Nazma Islam and Jonathan Barnes}, doi = {10.3847/1538-4357/adda32}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {181}, shortjournal = {The Astrophys. J.}, title = {Orbital phase-resolved analysis of X-ray and gamma-ray observations of the high-mass gamma-ray binary 4FGL j1405.1−6119}, volume = {986}, year = {2025}, }
• (2025). Study of waveguides and resonant cavities over sunspot volumes using multichannel solar dynamics observatory observations. ApJ, 986(2), 180. (www)

  @article{ , abstract = {For the first time, we have determined the spatial distribution of magnetic waveguides and resonant cavities at different heights of sunspot atmosphere. We analyzed the time series of EUV/UV images observed by the Solar Dynamics Observatory in the different temperature channels. We have decomposed these images into narrowband oscillating components, interpreted as wave sources. The methods of pixelized wavelet filtering and oscillation mode decomposition were used. For all studied sunspots, the presence of selected bands in the spectra was shown. Each band corresponds to oscillations forming spatial waveguides in the volume of the sunspot atmosphere. The formation of waveguide bundles in the height from photospheric to coronal levels is shown. The regions of the waveguides with maximum oscillating power, where resonant cavities are formed, are identified. Their detection is an experimental proof of the theory of resonant layers, previously proposed to explain the presence of significant harmonics in the oscillation spectrum. The different shapes of the cavities reflect the structure of the magnetic tubes along which the waves propagate. The distribution of sources in the height layers indicates the influence of the wave cutoff frequency caused by the inclinations of the magnetic field lines. We discuss the possibility of upward wave transport due to periodic amplification of the oscillating power in the detected cavities.}, archive = {J_ApJ}, author = {Robert Sych and Yihua Yan}, doi = {10.3847/1538-4357/adda48}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {180}, shortjournal = {The Astrophys. J.}, title = {Study of waveguides and resonant cavities over sunspot volumes using multichannel solar dynamics observatory observations}, volume = {986}, year = {2025}, }
• (2025). The physical origin of positive metallicity radial gradients in high-redshift galaxies: Insights from the FIRE-2 cosmological hydrodynamic simulations. ApJ, 986(2), 179. (www)

  @article{ , abstract = {Using the FIRE-2 cosmological zoom-in simulations, we investigate the temporal evolution of gas-phase metallicity radial gradients of Milky Way–mass progenitors in the redshift range of 0.4 < z < 3. We pay special attention to the occurrence of positive (i.e., inverted) metallicity gradients—where metallicity increases with galactocentric radius. This trend, contrary to the more commonly observed negative radial gradients, has been frequently seen in recent spatially resolved grism observations. The rate of occurrence of positive gradients in FIRE-2 is about ∼7% for 0.4 < z < 3 and ∼13% at higher redshifts (1.5 < z < 3), broadly consistent with observations. Moreover, we investigate the correlations among galaxy metallicity gradient, stellar mass, star formation rate (SFR), and degree of rotational support. Metallicity gradients show a strong correlation with both sSFR and the rotational-to-dispersion velocity ratio ( v c / σ ), implying that starbursts and kinematic morphology of galaxies play significant roles in shaping these gradients. The FIRE-2 simulations indicate that galaxies with high sSFR ( {\rm{log}}\,({\rm{sSFR}}\,[{{\rm{yr}}}^{-1}])\gtrsim -9.2 ) and weak rotational support ( v c / σ ≲ 1) are more likely—by ∼15%—to develop positive metallicity gradients. This trend is attributed to galaxy-scale gas flows driven by stellar feedback, which effectively redistribute metals within the interstellar medium. Our results support the important role of stellar feedback in governing the chemo-structural evolution and disk formation of Milky Way–mass galaxies at the cosmic noon epoch.}, archive = {J_ApJ}, author = {Xunda Sun and Xin Wang and Xiangcheng Ma and Kai Wang and Andrew Wetzel and Claude-André Faucher-Giguère and Philip F. Hopkins and Dušan Kereš and Russell L. Graf and Andrew Marszewski and Jonathan Stern and Guochao Sun and Lei Sun and Keyer Thyme}, doi = {10.3847/1538-4357/addab5}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {179}, shortjournal = {The Astrophys. J.}, title = {The physical origin of positive metallicity radial gradients in high-redshift galaxies: Insights from the FIRE-2 cosmological hydrodynamic simulations}, volume = {986}, year = {2025}, }
• (2025). Revisiting the li abundances of stars with and without detected planets from high-resolution spectroscopy. ApJ, 986(2), 178. (www)

  @article{ , abstract = {Whether the presence of planets affects the lithium (Li) abundance of their host stars is still an open question. To investigate the difference in the Li abundance between planet-host stars (HSs) and isolated stars (ISs) with no detected planets, we analyze a large sample of stars with temperatures ranging from 4600 to 6600 K and metallicity ranging from −0.55 to +0.50. The sample consists of 279 HSs whose spectra were taken from the California-Kepler Survey, which followed up planets detected by Kepler, and 171 ISs whose spectra were taken from the Keck archive. The non–local thermodynamic equilibrium (non-LTE) effects were taken into consideration. It is found that the distributions of Li abundances in both the HS and IS groups are generally consistent with each other. This suggests that the presence of Kepler-like planets does not have a significant impact on Li depletion. We also found that the non-LTE corrections cannot be neglected for stars with A(Li) over ∼2.5 dex.}, archive = {J_ApJ}, author = {Jinxiao Qin and Hong-Liang Yan and Wenyuan Cui and Jian-Rong Shi and Subo Dong and Shuai Liu and Zeming Zhou and Miao Tian and Zhenyan Huo and Xiangsong Fang and Jinghua Zhang and Chunqian Li and Mingyi Ding and Song Wang and Henggeng Han}, doi = {10.3847/1538-4357/addac3}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {178}, shortjournal = {The Astrophys. J.}, title = {Revisiting the li abundances of stars with and without detected planets from high-resolution spectroscopy}, volume = {986}, year = {2025}, }
• (2025). Here there be (Dusty) monsters: High-redshift active galactic nuclei are dustier than their hosts. ApJ, 986(2), 177. (www)

  @article{ , abstract = {JWST spectroscopy has discovered a population of z ≳ 3.5 galaxies with broad Balmer emission lines and narrow forbidden lines that are consistent with hosting active galactic nuclei (AGN). Many of these systems, now known as "little red dots," are compact and have unique colors that are very red in the optical/near-infrared and blue in the ultraviolet. The relative contribution of galaxy starlight and AGN to these systems remains uncertain, especially for the galaxies with unusual blue+red spectral energy distributions. In this work, we use Balmer decrements to measure the independent dust attenuation of the broad and narrow emission-line components of a sample of 29 broad-line AGN identified from three public JWST spectroscopy surveys: CEERS, JADES, and RUBIES. Stacking the narrow components from the spectra of 25 sources with broad H α and no broad H β results in a median narrow H α /H β = 2.4{7}_{-0.05}^{+0.05} (consistent with A v = 0) and broad H α /H β >8.85 ( A v > 3.63). The narrow and broad Balmer decrements imply little to no attenuation of the narrow emission lines, which are consistent with being powered by star formation and located on larger physical scales. Meanwhile, the lower limit in the broad H α /H β decrement, with broad H β undetected in the stacked spectrum of 25 broad H α AGN, implies significant dust attenuation of the broad-line emitting region that is presumably associated with the central AGN. Our results indicate that these systems, on average, are consistent with heavily dust-attenuated AGN powering the red parts of their SED, while their blue UV emission is powered by unattenuated star formation in the host galaxy.}, archive = {J_ApJ}, author = {Madisyn Brooks and Raymond C. Simons and Jonathan R. Trump and Anthony J. Taylor and Micaela B. Bagley and Bren Backhaus and Kelcey Davis and Véronique Buat and Nikko J. Cleri and Alexander de la Vega and Steven L. Finkelstein and Michaela Hirschmann and Benne W. Holwerda and Dale D. Kocevski and Anton M. Koekemoer and Ray A. Lucas and Fabio Pacucci and Lise-Marie Seillé}, doi = {10.3847/1538-4357/addac4}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {177}, shortjournal = {The Astrophys. J.}, title = {Here there be (Dusty) monsters: High-redshift active galactic nuclei are dustier than their hosts}, volume = {986}, year = {2025}, }
• (2025). Propagation and transmission of jupiter’s internal waves. ApJ, 986(2), 176. (www)

  @article{ , abstract = {Observations from the Juno spacecraft show that Jupiter has a large dilute core rather than a compact core. To investigate the effects of different core structures on wave propagation and transmission in Jupiter's interior, we consider three models: (1) an isentropic sphere, (2) an isentropic envelope with a rigid core, and (3) an isentropic envelope with a dilute core. We study the propagation and transmission of p -modes (sound waves), g -modes (gravity waves), r- modes (inertial waves), and gravito-inertial waves (GIWs) by solving the linear equations of a compressible, self-gravitating, uniformly rotating polytropic model, fully taking into account the the effects of the Coriolis force but neglecting centrifugal flattening. Our results show that energy flux is primarily carried by fast waves with higher frequencies, whereas kinetic energy is carried by slow waves with lower frequencies. Rotation has a greater effect on nonaxisymmetric modes than on axisymmetric ones. In Model 2, rigid core facilitates propagation of r -modes. In Model 3, rotation enhances the transmission of GIWs across the interface between the dilute core and the isentropic envelope, particularly at high latitudes. This suggests that Jupiter's internal structure may be inferred by detecting the oscillation signals in its polar regions.}, archive = {J_ApJ}, author = {Yuru Xu and Xing Wei}, doi = {10.3847/1538-4357/addbd9}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {176}, shortjournal = {The Astrophys. J.}, title = {Propagation and transmission of jupiter’s internal waves}, volume = {986}, year = {2025}, }
• (2025). Mapping the excitation mechanisms in the LINER i active galactic nucleus NGC 5005: Positive feedback and a thin LINER cocoon. ApJ, 986(2), 175. (www)

  @article{ , abstract = {We present a spatially resolved Baldwin–Phillips–Terlevich analysis of the narrow-line region (NLR) in the low-ionization nuclear emission-line region (LINER) I galaxy NGC 5005 using Hubble Space Telescope narrowband imaging of [O iii ] λ 5007, H β , H α , and [S ii ] λλ 6717,6731. With a resolution of ≲0 \mathop{.}\limits^{\unicode{x02033}} 1 (≲10 pc at z = 0.003), we dissect the NLR into H ii (star-forming), Seyfert, and LINERs across spatial scales extending up to r ∼ 8 kpc from the nucleus. Our results reveal a compact nuclear region exhibiting Seyfert-like emission, consistent with photoionization by a low-luminosity active galactic nucleus (AGN). Surrounding this Seyfert-like nucleus is a thin (∼20 pc thick) higher-excitation LINER-like cocoon, likely arising from shock-excited gas in the interstellar medium (ISM). Beyond this cocoon, a centrally localized extended ( r ∼ 1 kpc) LINER-like region surrounds the Seyfert-like nucleus and cocoon, likely ionized by the AGN, while a more extended ( r ≳ 2 kpc) LINER-like zone may be ionized by a combination of post-AGB stars and shocks from gas inflows. We also detect H ii –like regions at both small and large scales. In the inner 500 pc, these regions may be triggered by jet–ISM interactions, potentially inducing localized star formation. At r ∼ 4 kpc, we identify an outer H ii –like region tracing a large-scale star-forming ring, where ionization is dominated by young stars.}, archive = {J_ApJ}, author = {Anna Trindade Falcão and G. Fabbiano and M. Elvis and P. Zhu and S. Kraemer and W. P. Maksym and R. Middei and D. L. Król}, doi = {10.3847/1538-4357/addc64}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {175}, shortjournal = {The Astrophys. J.}, title = {Mapping the excitation mechanisms in the LINER i active galactic nucleus NGC 5005: Positive feedback and a thin LINER cocoon}, volume = {986}, year = {2025}, }
• (2025). A candidate for true type-2 AGN without hidden central broad-line regions identified by central tidal disruption event. ApJ, 986(2), 174. (www)

  @article{ , abstract = {In this manuscript, through applications of tidal disruption event (TDE) expected variability properties, a potential candidate for True Type-2 active galactic nuclei (TT2AGN) without hidden central broad-line regions (=TT2AGN) is reported in SDSS J233454.07+145712.9 (=SDSS J2334). Through analyzing the 20 yr optical light curves of SDSS J2334 from different Sky Survey projects, a TDE is preferred with a 4.7 M ⊙ main-sequence star tidally disrupted by the central black hole (BH) with mass 11.7 × 10 6 M ⊙ , indicating that central region within a distance of about 20 light days to the central BH in SDSS J2334 is directly in the line of sight. Moreover, active galactic nucleus (AGN) activities in SDSS J2334 can be confirmed through applications of (Baldwin, Phillips, & Terlevich (BPT) diagrams. Meanwhile, comparing virial BH mass determined through assumed broad Balmer emission components and M-sigma expected BH mass by well-measured stellar velocity dispersion through stellar absorption features, optical broad emission lines in SDSS J2334 are disfavored with confidence level higher than 6 σ . Therefore, combining the unique properties of the TDE and the spectroscopic results with only narrow emission lines, SDSS J2334 can be well identified as a potential candidate for a TT2AGN. The results indicate that to detect TDE expected flares in normal Type-2 AGN classified by spectroscopic results should be a new practicable method for identifying TT2AGN.}, archive = {J_ApJ}, author = {Ying Gu and Qi Zheng and Pei-zhen Cheng and Xiao Li and Xing-Qian Cheng and Xue-Guang Zhang and En-Wei Liang}, doi = {10.3847/1538-4357/addd0b}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {174}, shortjournal = {The Astrophys. J.}, title = {A candidate for true type-2 AGN without hidden central broad-line regions identified by central tidal disruption event}, volume = {986}, year = {2025}, }
• (2025). Quantum plasma creation near a magnetar. ApJ, 986(2), 173. (www)

  @article{ , abstract = {Magnetars in quiescent states continue to emit hard X-rays with a power far exceeding the loss of rotational energy. It has recently been noted that this hard X-ray continuum may bear a direct signature of quantum electrodynamic effects in magnetic fields stronger than the Schwinger field ( B Q = 4.4 × 10 13 G). Where the current flowing into the magnetosphere is driven by narrow structures in the solid crust, the e ± pair plasma supporting the current relaxes to a collisional and transrelativistic state. The decay of a pair into two photons produces a broad, bremsstrahlung-like spectrum of hard X-rays, similar to that observed and extending up to 0.5−1 MeV. The conversion of two gamma-rays to a pair is further enhanced by a factor ∼ B / B Q . Monte Carlo calculations of pair creation in a dipole magnetic field are presented. Nonlocal particle injection is found to be strong enough to suppress the high voltage that otherwise would accompany a weaker, global twist; the hard X-rays are mostly emitted away from the magnetic poles. Some of the pairs annihilate in an optically thin surface layer. The prototypical anomalous X-ray pulsar 1E 2259+586, which shows a hard X-ray continuum but relatively weak torque noise, slow spindown, and no radio emission, is a Rosetta Stone for understanding the magnetar circuit, consistent with the picture advanced here. For a 15−60 keV luminosity as low as 10 34 erg s −1 , the polar flux of subrelativistic pairs produces an optical depth of 3−30 to electron cyclotron scattering in the 1−10 keV band, reducing the net X-ray polarization.}, archive = {J_ApJ}, author = {Jonathan Zhang and Christopher Thompson}, doi = {10.3847/1538-4357/adabde}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {173}, shortjournal = {The Astrophys. J.}, title = {Quantum plasma creation near a magnetar}, volume = {986}, year = {2025}, }
• (2025). Evidence for YORP-induced spin deceleration in asteroid (433) eros. ApJ, 986(2), 172. (www)

  @article{ , abstract = {Theoretically, the Yarkovsky–O'Keefe–Radzievskii–Paddack (YORP) effect induced by thermal reemission from asteroid surfaces can either accelerate or decelerate their rotation. However, in the past decade or so, 12 asteroids confirmed to exhibit the YORP effect all show spinning-up behavior, raising questions about whether spinning-down asteroids exist and why they have not been definitively observed. Here, we present evidence that asteroid (433) Eros is undergoing spin deceleration, with an estimated YORP strength of υ = (−5.0 ± 4.6) × 10 −10 rad day −2 based on light curves spanning from 1953 to 2023. To account for possible systematic errors, we applied bootstrap resampling at the light-curve level. Besides, we also repeated the analysis on a subset of data with the most reliable light curves. While this reduced data set yields υ = (−3.0 ± 4.4) × 10 −10 rad day −2 , the optimal υ remains negative, suggesting a consistent trend. The discrepancy of υ values highlights the significant role of systematic errors in YORP detection. We calculated the theoretical YORP strength υ mod using both 1D and 3D heat conduction models and found it smaller than the observed value υ , perhaps due to surface heterogeneity. The well-studied Eros would be a perfect study object to make the YORP theory clearer.}, archive = {J_ApJ}, author = {Shuai Feng and Shaoming Hu and Xu Chen and Liyong Zhou and Yangbo Xu and Zehua Qi}, doi = {10.3847/1538-4357/addd23}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {172}, shortjournal = {The Astrophys. J.}, title = {Evidence for YORP-induced spin deceleration in asteroid (433) eros}, volume = {986}, year = {2025}, }
• (2025). Three-body mean motion resonance chains as a delivery mechanism for white dwarf pollution. ApJ, 986(2), 171. (www)

  @article{ , abstract = {In this work, we used numerical integration of the four-body problem to study three-body resonance chains (two planets and an asteroid in the innermost orbit) as a possible mechanism for white dwarf pollution. Two three-body resonance chains were selected for study: the 6:3:2 and the 4:2:1. Asteroids in both a dynamically colder initial orbit in the 6:3:2 resonance and hotter initial orbits in both resonances were studied. An asteroid had up to a 1.08% chance of being delivered to the stellar Roche limit of the white dwarf. This probability was strongly linearly correlated with the mass of the inner planet but was not correlated with the mass of the outer planet for both colder and hotter orbits. Average dynamical lifetimes ranged from 23 to 1137 kyr for the dynamically colder orbit and from 12.9 to 89.2 kyr and 10.8 to 793.4 kyr for the dynamically hotter orbits in the 6:3:2 and 4:2:1 resonances, respectively. Average dynamical lifetime was exponentially anticorrelated with the outer planet mass and usually with the inner planet mass except in one case. The hotter 4:2:1 resonance delivered 1.1 times more asteroids to the stellar Roche limit than the hotter 6:3:2 resonance. The hotter 6:3:2 resonance delivered 1.2 times more asteroids to the stellar Roche limit than the colder 6:3:2 resonance. A typical accretion rate for a white dwarf star of 10 8 g s −1 could be explained by the accretion of an equivalent mass of one of our simulated asteroids every 13.8 Myr.}, archive = {J_ApJ}, author = {Jeremy Wood and Natalie Cummins}, doi = {10.3847/1538-4357/addc5e}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {171}, shortjournal = {The Astrophys. J.}, title = {Three-body mean motion resonance chains as a delivery mechanism for white dwarf pollution}, volume = {986}, year = {2025}, }
• (2025). Insight-HXMT observations of the extremely bright GRB 221009A. ApJ, 986(2), 170. (www)

  @article{ , abstract = {The Insight Hard X-ray Modulation Telescope (Insight-HXMT) detected GRB 221009A, the brightest gamma-ray burst (GRB) observed to date, with all its three telescopes, i.e., the High Energy (HE) telescope (20–250 keV), Medium Energy (ME) telescope (5–30 keV), and Low Energy (LE) telescope (1–10 keV). Here we present the detailed observation results of all three telescopes of Insight-HXMT on the prompt emission of GRB 221009A. After dead-time and data saturation correction, we recovered the light curves of the HE, ME, and LE telescopes and find that they generally track the low-gain light curves of the third member of the Gravitational Wave High-energy Electromagnetic Counterpart All-sky Monitor (GECAM-C) that are free of data saturation issues. Particularly, the ME light curve matches the GECAM-C light curve in low gain mode above 400 keV, while the LE light curve is more consistent with the GECAM-C above 1.5 MeV. Based on simulation, we find that the signals recorded by ME and LE are actually caused by the secondary particles produced by the interaction between GRB gamma-ray photons and the material of the satellite. Interestingly, the consistency between the ME and LE light curves and GECAM-C demonstrates that ME and LE data could be used to characterize the GRB properties. Especially, the high-time-resolution light curve of ME allowed us, for the first time, to calculate the minimum variability timescale (0.10 s) of the main burst episode of GRB 221009A.}, archive = {J_ApJ}, author = {Wen-Long Zhang and Wang-Chen Xue and Cheng-Kui Li and Shao-Lin Xiong and Gang Li and Yong Chen and Wei-Wei Cui and Xiao-Bo Li and Cong-Zhan Liu and Ming-Yu Ge and Wen-Jun Tan and Jia-Cong Liu and Chen-Wei Wang and Chao Zheng and Yan-Qiu Zhang and Yue Wang and Zhen Zhang and Shu-Xu Yi and Shuo Xiao and Ce Cai and Shuang-Xi Yi and Li-Ming Song and Lian Tao and Shu Zhang and Shuang-Nan Zhang}, doi = {10.3847/1538-4357/add14f}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {170}, shortjournal = {The Astrophys. J.}, title = {Insight-HXMT observations of the extremely bright GRB 221009A}, volume = {986}, year = {2025}, }
• (2025). Quiet sun magnetism from ViSP data multiline inversions around 630.1 nm. ApJ, 986(2), 169. (www)

  @article{ , abstract = {Quiet Sun magnetism plays an important role in the global energy balance of the solar atmosphere. The study of the magnetism of the quiet Sun has been a major effort in the last decades, and, as a result, very important advances in our knowledge have been achieved. The recent commissioning of the Daniel K. Inouye Solar Telescope, the largest ground-based solar telescope in the world today, provides us with data of high spectropolarimetric quality and high spatial resolution. The combination of data acquired with the ViSP instrument on the DKIST telescope around 630.1 nm and multiline inversions enables the achievement of exceptionally high spatial resolution in the solar atmosphere, both at the surface and in depth. In this paper we determine the \mathrm{log}(gf) values of the spectral lines around 630.1 nm observed with the ViSP instrument and search for the best multi-inversion strategy, by means of MHD simulations, to analyze quiet Sun magnetism data within such spectral range. We present results of quiet Sun magnetism with special emphasis on its evolution with optical depth. In the internetwork, we find the decrease with height of the averaged magnetic field strength and the zone from which the fields become more horizontal. Additionally, we explore the depth-dependent evolution of the network's canopy, uncovering intriguing insights into its thermodynamic and magnetic properties. Notably, we detect a temperature enhancement in very localized areas of the vicinity of the network and distinguish mass motions with opposing velocities inside the flux tubes.}, archive = {J_ApJ}, author = {J. C. Trelles Arjona}, doi = {10.3847/1538-4357/adceca}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {169}, shortjournal = {The Astrophys. J.}, title = {Quiet sun magnetism from ViSP data multiline inversions around 630.1 nm}, volume = {986}, year = {2025}, }
• (2025). Dusty stellar source classification by implementing machine learning methods based on spectroscopic observations in the magellanic clouds. ApJ, 986(2), 168. (www)

  @article{ , abstract = {Dusty stellar point sources are a significant stage in stellar evolution and contribute to the metal enrichment of galaxies. These objects can be classified using photometric and spectroscopic observations using color–magnitude diagrams and infrared excesses in spectral energy distributions. We have employed supervised machine learning spectral classification to categorize dusty stellar point sources, including young stellar objects (YSOs) and evolved stars comprising oxygen- and carbon-rich asymptotic giant branch stars (AGBs), red supergiants (RSGs), and post-AGB stars (PAGBs) in the Large and Small Magellanic Clouds, based on spectroscopic labeled data derived from the Surveying the Agents of Galaxy Evolution (SAGE) project, which involved 12 multiwavelength filters and 618 stellar objects. Despite dealing with missing values and uncertainties in the SAGE spectral data sets, we achieved accurate classifications of these sources. To address the challenge of working with small and imbalanced spectral catalogs, we utilized the Synthetic Minority Oversampling Technique (SMOTE), which generates synthetic data points. Subsequently, among all the models applied before and after data augmentation, the probabilistic random forest (PRF) classifier, a tuned random forest, demonstrated the highest total accuracy, reaching 89% based on the recall metric in categorizing dusty stellar sources. In this study, using the SMOTE technique does not improve the accuracy of the best model for the CAGB, PAGB, and RSG classes; it stays at 100%, 100%, and 88%, respectively. However, there are variations in the OAGB and YSO classes. Accordingly, we collected photometrically labeled data with properties similar to the training data set and classified them using the top four PRF models with an accuracy of more than 87%. We also collected multiwavelength data from several studies to classify them using our consensus model, which integrates the four top models to present common labels as the final prediction.}, archive = {J_ApJ}, author = {Sepideh Ghaziasgar and Mahdi Abdollahi and Atefeh Javadi and Jacco Th. van Loon and Iain McDonald and Joana Oliveira and Amirhossein Masoudnezhad and Habib G. Khosroshahi and Bernard H. Foing and Fatemeh Fazel Hesar}, doi = {10.3847/1538-4357/adceeb}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {168}, shortjournal = {The Astrophys. J.}, title = {Dusty stellar source classification by implementing machine learning methods based on spectroscopic observations in the magellanic clouds}, volume = {986}, year = {2025}, }
• (2025). Diffuse X-ray emission in m51: A hierarchical bayesian spatially resolved spectral analysis. ApJ, 986(2), 167. (www)

  @article{ , abstract = {X-ray observations can be used to effectively probe the galactic ecosystem, particularly its hot and energetic components. However, existing X-ray studies of nearby star-forming galaxies are limited by insufficient data statistics and a lack of suitable spectral modeling to account for X-ray emission and absorption geometry. We present results from an X-ray spectral study of M51 using 1.3 Ms Chandra data, the most extensive for such a galaxy. This allows the extraction of diffuse X-ray emission spectra from phase-dependent regions of spiral arms using a logarithmic spiral coordinate system. A hierarchical Bayesian approach analyzes these spectra, testing models from simple single-temperature hot plasma to those including distributed hot plasma and X-ray-absorbing cool gas. We recommend a model that fits the spectra well, featuring a galactic corona with a lognormal temperature distribution and a disk with mixed X-ray emissions and absorption. In this model, only half of the coronal emission is subject to internal absorption. The best-fit column density of absorbing gas is roughly twice that inferred from optical extinction of stellar light. The temperature distribution shows a mean temperature of ∼0.1 keV and an average one-dex dispersion that is enhanced on the spiral arms. The corona's radiative cooling might balance the mechanical energy input from stellar feedback. These results highlight the effectiveness of X-ray mapping of the corona and cool gas in spiral galaxies.}, archive = {J_ApJ}, author = {Luan Luan and Q. Daniel Wang}, doi = {10.3847/1538-4357/adcf16}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {167}, shortjournal = {The Astrophys. J.}, title = {Diffuse X-ray emission in m51: A hierarchical bayesian spatially resolved spectral analysis}, volume = {986}, year = {2025}, }
• (2025). Quantifying uncertainties in solar wind forecasting due to incomplete solar magnetic field information. ApJ, 986(2), 166. (www)

  @article{ , abstract = {Solar wind forecasting plays a crucial role in space weather prediction, yet significant uncertainties persist duet to incomplete magnetic field observations of the Sun. Isolating the solar wind forecasting errors due to these effects is difficult. This study investigates the uncertainties in solar wind models arising from these limitations. We simulate magnetic field maps with known uncertainties, including far-side and polar field variations, as well as resolution and sensitivity limitations. These maps serve as input for three solar wind models: the Wang–Sheeley–Arge, the Heliospheric Upwind eXtrapolation, and the European Heliospheric FORecasting Information Asset. We analyze the discrepancies in solar wind forecasts, particularly the solar wind speed at Earth's location, by comparing the results of these models to a created ground truth magnetic field map, which is derived from a synthetic solar rotation evolution using the Advective Flux Transport model. The results reveal significant variations within each model with a root mean square error ranging from 59 to 121 km s −1 . Further comparison with the thermodynamic Magnetohydrodynamic Algorithm outside a Sphere model indicates that uncertainties in the different models can lead to even larger variations in solar wind forecasts compared to those within a single model. However, predicting a range of solar wind velocities based on a cloud of points around Earth can help mitigate uncertainties by up to 20%–77%.}, archive = {J_ApJ}, author = {Stephan G. Heinemann and Jens Pomoell and Ronald M. Caplan and Mathew J. Owens and Shaela Jones and Lisa Upton and Bibhuti Kumar Jha and Charles N. Arge}, doi = {10.3847/1538-4357/adcf9e}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {166}, shortjournal = {The Astrophys. J.}, title = {Quantifying uncertainties in solar wind forecasting due to incomplete solar magnetic field information}, volume = {986}, year = {2025}, }
• (2025). Broad-line AGNs at 3.5 < z < 6: The black hole mass function and a connection with little red dots. ApJ, 986(2), 165. (www)

  @article{ , abstract = {We present a sample of 62 H α detected broad-line active galactic nuclei (BLAGNs) at redshifts 3.5 < z < 6.8 using data from the CEERS and RUBIES surveys. We select these sources directly from JWST/NIRSpec G395M/F290LP spectra. We use a multistep pre-selection and Bayesian fitting to ensure a high-quality sample of sources with broad Balmer lines and narrow forbidden lines. We compute rest-frame ultraviolet and optical spectral slopes for these objects, and determine that 21 BLAGNs in our sample are also little red dots (LRDs). These LRD BLAGNs, when examined in aggregate, show broader H α line profiles and a higher fraction of broad-to-narrow component H α emission than non-LRD BLAGNs. We find that ∼90% of LRD BLAGNs are intrinsically reddened ( β opt > 0), independent of contributions from emission lines to the broadband photometry. We construct the black hole (BH) mass function at 3.5 < z < 6 after computing robust completeness corrections. This BH mass function shows agreement with recent JWST-based BH mass functions, though we extend these earlier results to log ( M BH / M ⊙ ) < 7. The derived BH mass function is consistent with theoretical models, indicating that the observed abundance of BHs in the early Universe may not be discrepant with physically motivated predictions. The BH mass function shape resembles a largely featureless power law, suggesting that signatures from BH seeding have been lost by redshift z ∼ 5–6. Finally, we compute the BLAGN UV luminosity function and find agreement with JWST-detected BLAGN samples from recent works, finding that BLAGN hosts constitute ≲10% of the total observed UV luminosity at all but the brightest luminosities.}, archive = {J_ApJ}, author = {Anthony J. Taylor and Steven L. Finkelstein and Dale D. Kocevski and Junehyoung Jeon and Volker Bromm and Ricardo O. Amorín and Pablo Arrabal Haro and Bren E. Backhaus and Micaela B. Bagley and Eduardo Banados and Rachana Bhatawdekar and Madisyn Brooks and Antonello Calabrò and Óscar A. Chávez Ortiz and Yingjie Cheng and Nikko J. Cleri and Justin W. Cole and Kelcey Davis and Mark Dickinson and Callum Donnan and James S. Dunlop and Richard S. Ellis and Vital Fernández and Adriano Fontana and Seiji Fujimoto and Mauro Giavalisco and Andrea Grazian and Jingsong Guo and Nimish P. Hathi and Benne W. Holwerda and Michaela Hirschmann and Kohei Inayoshi and Jeyhan S. Kartaltepe and Yana Khusanova and Anton M. Koekemoer and Vasily Kokorev and Rebecca L. Larson and Gene C. K. Leung and Ray A. Lucas and Derek J. McLeod and Lorenzo Napolitano and Masafusa Onoue and Fabio Pacucci and Casey Papovich and Pablo G. Pérez-González and Nor Pirzkal and Rachel S. Somerville and Jonathan R. Trump and Stephen M. Wilkins and L. Y. Aaron Yung and Haowen Zhang}, doi = {10.3847/1538-4357/add15b}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {165}, shortjournal = {The Astrophys. J.}, title = {Broad-line AGNs at 3.5 < z < 6: The black hole mass function and a connection with little red dots}, volume = {986}, year = {2025}, }
• (2025). Discovery of the hybrid response of photoionized gases. ApJ, 986(2), 164. (www)

  @article{ , abstract = {Photoionized gases are prevalent throughout the Universe. In such gases, the ion concentration typically exhibits two response modes to radiation: a positive response in the low-ionization state and a negative response in the high-ionization state. Here, we report the discovery of a widespread misalignment at the boundary between the above two response modes and identify a third mode—the hybrid response—through time-dependent photoionization simulations. This phenomenon arises from the asynchrony among the ionization rate, recombination rate, and ion column density. Among these, only the ionization rate can respond instantaneously to changes in radiation. Consequently, the initial rate of change in the column density of N i ion is given by − N i I i + N i −1 I i −1 . However, this quantity is typically nonzero at the peak of N i , leading to a misalignment between the boundaries of positive and negative responses. Such hybrid effects introduce additional complexity in the interpretation of gas properties, highlighting the need for further investigation.}, archive = {J_ApJ}, author = {Zhicheng He and Tinggui Wang and Gary J. Ferland}, doi = {10.3847/1538-4357/addf50}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {164}, shortjournal = {The Astrophys. J.}, title = {Discovery of the hybrid response of photoionized gases}, volume = {986}, year = {2025}, }
• (2025). Pair-instability gap black holes in population III star clusters: Pathways, dynamics, and gravitational-wave implications. ApJ, 986(2), 163. (www)

  @article{ , abstract = {The detection of the gravitational-wave (GW) event GW190521 raises questions about the formation of black holes (BHs) within the pair-instability mass gap (PIBHs). We propose that Population III star clusters significantly contribute to events similar to GW190521. We perform N -body simulations and find that PIBHs can form from stellar collisions or binary black hole (BBH) mergers, with the latter accounting for 90% of the contributions. Due to GW recoil during BBH mergers, approximately 10%–50% of PIBHs formed via BBH mergers that escaped from clusters, depending on BH spins and cluster escape velocities. The remaining PIBHs can participate in secondary and multiple BBH formation events, contributing to GW events. Assuming Population III stars form in massive clusters (initially 100,000 M ⊙ ) with a top-heavy initial mass function, the average merger rates for GW events involving PIBHs with 0% and 100% primordial binaries are 0.005 and 0.017 yr −1 Gpc −3 , respectively, with maximum values of 0.030 and 0.106 yr −1 Gpc −3 . If Population III stars form in low-mass clusters (initial mass of 1000 M ⊙ and 10,000 M ⊙ ), the merger rate is comparable with a 100% primordial binary fraction but significantly lower without primordial binaries. We also calculate the characteristic strains of the GW events in our simulations and find that about 43.4% (LISA), 97.8% (Taiji), and 66.4% (Tianqin) of these events could potentially be detected by space-borne detectors, including LISA, Taiji, and TianQin. Next-generation GW detectors such as DECIGO, the Einstein Telescope, and Cosmic Explorer can nearly cover all these signals.}, archive = {J_ApJ}, author = {Weiwei Wu and Long Wang and Shuai Liu and Yining Sun and Ataru Tanikawa and Michiko Fujii}, doi = {10.3847/1538-4357/add1df}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {163}, shortjournal = {The Astrophys. J.}, title = {Pair-instability gap black holes in population III star clusters: Pathways, dynamics, and gravitational-wave implications}, volume = {986}, year = {2025}, }
• (2025). A systematic search for galaxies with extended emission lines and potential outflows in JADES medium-band images. ApJ, 986(2), 162. (www)

  @article{ , abstract = {For the first time, we present a systematic search for galaxies with extended emission lines and potential outflow features using JWST medium-band images in the GOODS South field. This is done by comparing the morphology in medium-band images to adjacent continuum and UV bands. We look for galaxies that have a maximum extent 50% larger, an excess area 30% greater, or an axis ratio difference of more than 0.3 in the medium band compared to the reference bands. After visual inspection, we find 326 candidate galaxies at 1.4 < z < 8.4, with a peak in the population near cosmic noon, benefiting from the good coverage of the medium-band filters. By fitting their spectral energy distributions, we find that the candidate galaxies are at least 20% more bursty in their star-forming activity and have 50% more young stellar populations compared to a control sample selected based on the continuum band flux. Additionally, these candidates exhibit a significantly higher production rate of ionizing photons. We further find that candidates hosting known active galactic nuclei (AGN) produce extended emission that is more anisotropic compared to non-AGN candidates. A few of our candidates have been spectroscopically confirmed to have prominent outflow signatures through NIRSpec observations, showcasing the robustness of the photometric selection. Future spectroscopic follow-up will better help verify and characterize the kinematics and chemical properties of these systems.}, archive = {J_ApJ}, author = {Yongda Zhu and Marcia J. Rieke and Zhiyuan Ji and Charlotte Simmonds and Fengwu Sun and Yang Sun and Stacey Alberts and Rachana Bhatawdekar and Andrew J. Bunker and Phillip A. Cargile and Stefano Carniani and Anna de Graaff and Kevin Hainline and Jakob M. Helton and Gareth C. Jones and Jianwei Lyu and George H. Rieke and Pierluigi Rinaldi and Brant Robertson and Jan Scholtz and Hannah Übler and Christina C. Williams and Christopher N. A. Willmer}, doi = {10.3847/1538-4357/add2f4}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {162}, shortjournal = {The Astrophys. J.}, title = {A systematic search for galaxies with extended emission lines and potential outflows in JADES medium-band images}, volume = {986}, year = {2025}, }
• (2025). Observational signatures of disk winds in protoplanetary disks: Differentiating magnetized and photoevaporative outflows with fully coupled thermochemistry. ApJ, 986(2), 161. (www)

  @article{ , abstract = {Magnetized winds and photoevaporative winds are critical in shaping protoplanetary disk evolution. Using 2D axisymmetric (magneto)hydrodynamic simulations with fully coupled thermochemistry, we investigate the signatures of the two winds in CO and [C I ] Atacama Large Millimeter/submillimeter Array (ALMA) observations, and examine the potential to distinguish the origins. Our simulations reveal fundamental differences between the two winds: magnetized winds are colder and denser, exhibiting super-Keplerian rotation with small poloidal velocities of ≲1 km s −1 in the atmosphere ( z / R ≳ 0.45), while photoevaporative winds are hotter and less dense, exhibiting sub-Keplerian rotation with higher poloidal velocities of several kilometers per second. In addition to previously identified factors like thermal pressure gradient and disk's self-gravity, we demonstrate that magnetic force and advection significantly influence rotational velocities of the gas in the wind, which lead to emission patterns that are distinct from Keplerian rotation in synthetic ALMA observations. Magnetized winds are visible in CO channel maps when wind loss rates are ≳10 −8 M ⊙ yr −1 . When wind loss rates are lower, magnetized winds produce subtle perturbations that resemble those produced by protoplanets. While strong X-ray and ultraviolet radiation photodissociates CO in photoevaporative winds, they can create observable ring-like substructures at disk surfaces. [C I ] emission is optically thin and could be most effective at detecting both winds in disks with high gas mass and/or high [C I ] abundance. Due to the spatially extended nature of the winds, using a large beam ( \simeq 0\mathop{.}\limits^{^{\prime\prime} }4 for disks in nearby star-forming regions) will be helpful regardless of the tracer used.}, archive = {J_ApJ}, author = {Xiao Hu and Jaehan Bae and Zhaohuan Zhu and Lile Wang}, doi = {10.3847/1538-4357/add300}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {161}, shortjournal = {The Astrophys. J.}, title = {Observational signatures of disk winds in protoplanetary disks: Differentiating magnetized and photoevaporative outflows with fully coupled thermochemistry}, volume = {986}, year = {2025}, }
• (2025). Newly discovered changing-look active galactic nuclei from SDSS and LAMOST survey. ApJ, 986(2), 160. (www)

  @article{ , abstract = {Changing-look active galactic nuclei (CL AGNs) exhibit drastic variations in broad emission lines (BELs), the mechanism of which remains unclear. Expanding the sample of CL AGNs is helpful to reveal the mechanism. This study aims to identify more CL AGNs by crossmatching spectroscopic data from the Sloan Digital Sky Survey and the Large Sky Area Multi-Object Fiber Spectroscopic Telescope. Our approach to identifying CL AGNs is based on automatic spectral fitting, followed by detailed visual inspections. We identify a sample of 51 CL AGNs through this method, in which 40 CL AGNs are newly discovered. Within this sample, 41 CL AGNs primarily show the variability of the H β line, nine exhibit obvious changes in both the H β and H α lines, and one source mainly displays variations in the H α line. Our findings reveal that the sequence of appearance and disappearance of the BELs aligns with the known CL sequence. In addition, we identify 31 candidates exhibiting drastic variations in BELs without accompanying significant photometric variability. We estimate the black hole mass and Eddington ratio for all sources, which range from 2.5 × 10 6 to 8.0 × 10 8 M ⊙ and from 0.001 to 0.13, respectively. Similar to other studies, we also find that the Eddington ratios of CL AGNs and candidates are lower than those of typical AGNs. Our results support the hypothesis that the CL behavior is driven by the state transitions of the accretion disk.}, archive = {J_ApJ}, author = {Qian Dong and Zhi-Xiang Zhang and Wei-Min Gu and Mouyuan Sun and Yong-Gang Zheng}, doi = {10.3847/1538-4357/add331}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {160}, shortjournal = {The Astrophys. J.}, title = {Newly discovered changing-look active galactic nuclei from SDSS and LAMOST survey}, volume = {986}, year = {2025}, }
• (2025). Thermodynamics of the h ii region sh2-158 and “Direct” measurement of its turbulence. ApJ, 986(2), 159. (www)

  @article{ , abstract = {Three SITELLE hyperspectral cubes were used to obtain 12 million spectra sampling 11 emission lines of the H ii region Sh2-158. This data set enables the calculation of numerous diagnostics and physical parameters such as abundance, electronic density, temperature, and pressure. The thermodynamic study of the nebula revealed interesting results. From [S ii ] and [N ii ] line ratio diagnostics, electronic density and temperature maps were calculated by an iterative computation method. A Monte Carlo analysis was implemented to determine accurate uncertainties for all physical parameters. We thus measured median electronic density and temperature values of 370 cm −3 and 7020 K from the iterative maps. Examining the global maps and the sampled subregions, complex patterns of density and temperature gradients/variations are observed. We produce an electronic pressure map that shows diminishing pressure, a factor of 10, from the molecular cloud to the outskirts of Sh2-158. Fabry–Perot observations complete the data to further the dynamical analysis of Sh2-158. Supersonic turbulent velocities are "directly" measured from the [N ii ] 6584 Å. Three statistical tools are used to analyze velocity centroid and nonthermal linewidth maps. The analysis of the velocity fluctuations shows the presence of intermittency. This phenomenon can produce the temperature fluctuations that are suggested to explain the abundance discrepancy problem in H ii regions.}, archive = {J_ApJ}, author = {Maxime Royer and Gilles Joncas and Mathieu Marquis}, doi = {10.3847/1538-4357/add334}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {159}, shortjournal = {The Astrophys. J.}, title = {Thermodynamics of the h ii region sh2-158 and “Direct” measurement of its turbulence}, volume = {986}, year = {2025}, }
• (2025). Radiation magnetohydrodynamic simulation of sub-eddington circumbinary disk around an equal-mass massive black hole binary. ApJ, 986(2), 158. (www)

  @article{ , abstract = {We present the first three-dimensional radiation magnetohydrodynamic (RMHD) simulation of a sub-Eddington circumbinary disk (CBD) around an equal-mass massive black hole binary with a total mass of 2 × 10 7 M ⊙ on a circular orbit, separated by 100 GM tot / c 2 . The inclusion of radiation leads to a denser, thinner, and more filamentary disk compared to nonradiative magnetohydrodynamic simulation, primarily due to reduced pressure support and an altered equation of state. The RMHD disk also features ∼3 times lower accretion rate ( \approx 0.15\,{\dot{M}}_{{\rm{Edd}}} ), weaker accretion streams, and a less pronounced overdensity (a.k.a., "lump") at the inner edge. Our analysis of the light curves and thermal spectra reveals that the variability induced by the binary–CBD interaction is distinguishable in the optical/UV band, where CBD shines at about 1% of the Eddington luminosity. These findings underscore the crucial role of radiation on the structure and observational properties of CBDs around massive black hole binaries and have implications for detecting electromagnetic counterparts to Laser Interferometer Space Antenna gravitational-wave precursors, and for heavier binaries that are Pulsar Timing Array sources.}, archive = {J_ApJ}, author = {Vishal Tiwari and Chi-Ho Chan and Tamara Bogdanović and Yan-Fei Jiang and Shane W. Davis and Simon Ferrel}, doi = {10.3847/1538-4357/add408}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {158}, shortjournal = {The Astrophys. J.}, title = {Radiation magnetohydrodynamic simulation of sub-eddington circumbinary disk around an equal-mass massive black hole binary}, volume = {986}, year = {2025}, }
• (2025). Generalized two thermal regime approach: Bipoly fluid modeling. ApJ, 986(2), 157. (www)

  @article{ , abstract = {The isopoly bifluid approach assumes an isothermal evolution of the solar wind near the Sun up to the radial distance r iso , followed by a polytropic evolution constrained by the observed polytropic indices. This approach provides a more accurate model of the interplanetary fluid properties of the solar wind and their radial evolution than Parker's isothermal and polytropic wind. In this article, we present an improvement of the isopoly approach by considering a generalized two thermal regime approach, embedding two distinct polytropic evolutions, the "bipoly" modeling. To demonstrate the capability of the approach, the models are fitted to both interplanetary and coronal observations, all classified by wind speed population in the spirit of M. Maksimovic et al. The set of observations used as constraints are coronal temperatures inferred from charge-state ratio observations from Solar Orbiter, and interplanetary measurements from Helios and Parker Solar Probe. The relaxation of the isothermal criteria in the near-Sun region permits one to significantly improve the fast wind acceleration for low-coronal-temperature conditions. In summary, the new model matches closely the observational constraints: the coronal temperature and the radial evolution of the wind plasma properties in the interplanetary medium, and this for all the wind speed populations.}, archive = {J_ApJ}, author = {Jean-Baptiste Dakeyo and Pascal Démoulin and Alexis Rouillard and Milan Maksimovic and Alice Chapiron and Stuart Bale}, doi = {10.3847/1538-4357/add473}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {157}, shortjournal = {The Astrophys. J.}, title = {Generalized two thermal regime approach: Bipoly fluid modeling}, volume = {986}, year = {2025}, }
• (2025). Unveiling the aromatic and aliphatic universe at redshifts z ∼ 0.2–0.5 with JWST NIRCam/WFSS. ApJ, 986(2), 156. (www)

  @article{ , abstract = {Utilizing deep NIRCam/WFSS data from JWST's FRESCO program, we spectroscopically survey the 3.3 μ m aromatic and 3.4 μ m aliphatic C–H stretching emission bands of polycyclic aromatic hydrocarbon (PAH) molecules in galaxies at redshifts z ∼ 0.2–0.5. Unlike pre-JWST studies, largely limited to infrared (IR)-bright galaxies ( L IR ≳ 10 11 L ⊙ ) at z ≲ 0.1, we probe 200 galaxies down to L IR ∼ 10 8.5 –10 10 L ⊙ , well beyond the local Universe. The 3.3 μ m emission is detected at ≥3 σ in 88 out of 187 galaxies, correlating tightly with galaxy IR luminosity and star formation rate (SFR) and confirming the 3.3 μ m PAH as a viable SFR tracer. Despite a large scatter, the 3.3 μ m–to–IR luminosity ratio ( L 3.3 / L IR ) exhibits a strong metallicity dependence with a drop of L 3.3 / L IR by a factor of ≳10 at 12+log(O/H) ∼ 8.4–8.5 toward lower metallicities. The 3.4 μ m emission is detected in 37 out of 159 galaxies, with the 3.4 μ m–to–3.3 μ m luminosity ratio ( L 3.4 / L 3.3 ) spanning from ∼0.05 to ∼0.58 (median ∼0.19), corresponding to PAH aliphatic fractions of ∼0.78%–8.3% (median ∼2.9%) in terms of fractional carbon atoms in aliphatic units. While L 3.4 / L 3.3 does not depend significantly on redshift, stellar mass, metallicity, or galaxy morphology, it does decrease with various SFR tracers, suggesting that ultraviolet photons in active star-forming regions may strip aliphatic side groups from PAH molecules. Our study showcases the unique power of JWST's NIRCam/WFSS to systematically map PAH aromatic and aliphatic content in statistically significant, less biased galaxy samples, providing critical insights into PAH chemistry and its connection to galaxy properties.}, archive = {J_ApJ}, author = {Jianwei Lyu and Xuejuan Yang and Aigen Li and Fengwu Sun and George H. Rieke and Stacey Alberts and Irene Shivaei}, doi = {10.3847/1538-4357/add538}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {156}, shortjournal = {The Astrophys. J.}, title = {Unveiling the aromatic and aliphatic universe at redshifts z ∼ 0.2–0.5 with JWST NIRCam/WFSS}, volume = {986}, year = {2025}, }
• (2025). Detection of intermediate-mass ratio inspirals in globular clusters: Revealing the brownian motion with gravitational waves. ApJ, 986(2), 155. (www)

  @article{ , abstract = {Intermediate-mass ratio inspirals (IMRIs) formed by stellar-mass compact objects orbiting intermediate-mass black holes will be detected by future gravitational wave (GW) observatories like TianQin, LISA, and AION. We study a set of 100 IMRI systems in globular clusters obtained from MOCCA simulations to estimate their detectability. Furthermore, we model the Brownian motion of the IMRIs induced by weak interactions with the surrounding field of stars and include its effect on the GW's phase through Doppler and aberrational phase shift. We find that a small fraction of IMRIs (<10%) will have signal-to-noise ratios (SNRs) high enough to be detected by TianQin, LISA, and AION. However, for all sources detected, the SNR is high enough to discern the Brownian motion of the IMRI. More precisely, we find that the match between the signal containing the effect of the Brownian motion and a waveform model without this effect is mostly low (<0.8). These results highlight the importance of including the interaction of IMRIs with the surrounding field of stars to obtain proper detection, but also show the possibility of studying the environment of the source using GWs.}, archive = {J_ApJ}, author = {Alejandro Torres-Orjuela and Verónica Vázquez-Aceves and Tian-Xiao Wang}, doi = {10.3847/1538-4357/add5f4}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {155}, shortjournal = {The Astrophys. J.}, title = {Detection of intermediate-mass ratio inspirals in globular clusters: Revealing the brownian motion with gravitational waves}, volume = {986}, year = {2025}, }
• (2025). Magnetic flux transport signatures of electron-only and ion-coupled magnetic reconnection in plasma turbulence. ApJ, 986(2), 154. (www)

  @article{ , abstract = {Electron-only magnetic reconnection was first detected by the Magnetospheric Multiscale (MMS) mission in Earth's turbulent magnetosheath. Its prevalence in kinetic-scale turbulence has attracted great interest in heliophysics, but also revealed a great challenge in identifying it in turbulence, where electron flows are often complex. The magnetic flux transport (MFT) method is an innovative method to identify active reconnection in numerical simulations and in situ observations of turbulent plasmas. Here we extend this method to distinguish between electron-only and ion-coupled reconnection. The coupling of magnetic field motion with plasma flows in the diffusion regions sets distinct scales in the MFT velocity. While both forms of reconnection satisfy the MFT signature for active reconnection as MFT inflows and outflows at an X-line, the specific electron-only MFT signature is only an electron-scale MFT outflow along the current sheet normal direction, whereas the specific ion-coupled signature is a two-scale, outer-ion-and-inner-electron-scale MFT outflow in the electron diffusion region, which evolves into a single ion-scale in the ion diffusion region. These signatures are verified in a simulation of gyrokinetic turbulence. The dependence of the MFT outflow on the distance downstream from the X-lines also agrees well with the framework of magnetic field–plasma flow coupling. The new MFT signatures provide a clear and reliable tool for investigating electron-only reconnection in turbulence, independent of the development of electron outflows. They are directly applicable to kinetic and fluid simulations, and have potential application to observations of diffusion region crossings by spacecraft missions such as MMS.}, archive = {J_ApJ}, author = {Tak Chu Li and Yi-Hsin Liu and Yi Qi}, doi = {10.3847/1538-4357/add882}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {154}, shortjournal = {The Astrophys. J.}, title = {Magnetic flux transport signatures of electron-only and ion-coupled magnetic reconnection in plasma turbulence}, volume = {986}, year = {2025}, }
• (2025). The effect of the fast-flavor instability on core-collapse supernova models. ApJ, 986(2), 153. (www)

  @article{ , abstract = {Merging our supernova code F ornax with the Box3D fast-flavor neutrino oscillation formalism, we explore the effects of fast-flavor conversion (FFC) in state-of-the-art one-dimensional (1D) and two-dimensional (2D) core-collapse supernova simulations. We find that after a few tens of milliseconds after bounce the FFC emerges just interior and exterior to the stalled shock wave. It does not obtain in the protoneutron star core nor near the average neutrinosphere radii. Interior to the shock, this results in a temporary change in the net neutrino heating rate of ∼10%, due mostly to a hardening of the ν e and {\bar{\nu }}_{e} neutrino spectra, despite the decrease in their corresponding neutrino number fluxes. In 1D, the hydrodynamic effects are not large, with increases in the stalled shock radius by of order 10 to 20 km that abate within a few hundred milliseconds. In 2D, the hydrodynamic effect of the FFC is a bit more noticeable, resulting in slightly earlier explosions for models for lower-mass progenitors but also potentially inhibiting explosions for some higher-mass progenitors. FFC continues to operate at larger radii at later times. The net result is a shift upward in the ν μ energy and number luminosities and a shift downward in the same quantities for both the ν e and {\bar{\nu }}_{e} neutrinos. There seems to be a trend at very large radii and later times toward partial species and spectral equipartition. If this is true, it could be an interesting feature of supernova neutrino detection at later times in underground and under-ice facilities.}, archive = {J_ApJ}, author = {Tianshu Wang and Adam Burrows}, doi = {10.3847/1538-4357/add889}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {153}, shortjournal = {The Astrophys. J.}, title = {The effect of the fast-flavor instability on core-collapse supernova models}, volume = {986}, year = {2025}, }
• (2025). A new shock in the premerging cluster pair 1E2215-2216. ApJ, 986(2), 152. (www)

  @article{ , abstract = {The galaxy cluster pair 1E2216.0-0401 and 1E2215.7-0404 represents a major cluster merger in its early stages, a phase that has been scarcely explored in previous studies. Within this system, both axial and equatorial merger shocks have been identified. Recent XMM-Newton observations of the southern region of the cluster pair have increased the total exposure time to approximately 300 ks, enhancing the sensitivity to detect faint shock features in the cluster outskirts. Through a combined analysis of XMM-Newton and Chandra data, including both imaging and spectral techniques, a new shock front has been identified at approximately 2 \mathop{.}\limits^{{\rm{^{\prime} }}} 3 south of the X-ray brightness peak of 1E2215. This shock front exhibits a surface brightness ratio of 1.33 ± 0.07 and a temperature ratio of 1.2{2}_{-0.14}^{+0.13} in XMM-Newton, consistent with Chandra results. The Mach number, independently calculated from both the temperature and surface brightness discontinuities, yields consistent values of { \mathcal M }\approx 1.2 . The age, velocity, and spatial distribution of this shock suggest that it shares a common physical origin with the previously identified equatorial shock.}, archive = {J_ApJ}, author = {Yanling Chen and Liyi Gu and Aurora Simionescu and Chunyang Jiang and Rui Huang and Wei Cui}, doi = {10.3847/1538-4357/add933}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {152}, shortjournal = {The Astrophys. J.}, title = {A new shock in the premerging cluster pair 1E2215-2216}, volume = {986}, year = {2025}, }
• (2025). Gravitational waves from primordial black hole dark matter spikes. ApJ, 986(2), 151. (www)

  @article{ , abstract = {The origin of the binary black hole mergers observed by LIGO–Virgo–KAGRA remains an open question. We calculate the merger rate from primordial black holes (PBHs) within the density spike around supermassive black holes (SMBHs) at the centers of galaxies. We show that the merger rate within the spike is comparable to that within the wider dark matter halo. We also calculate the extreme mass ratio inspiral (EMRI) signal from PBHs hosted within the density spike spiralling into their host SMBHs due to gravitational-wave emission. We predict that LISA may detect ∼10 4 of these EMRIs with a signal-to-noise ratio threshold of 20 within a 4 yr observation run, if all dark matter is made up of ∼30 M ⊙ PBHs. Uncertainties in our rates come from the uncertain mass fraction of PBHs within the dark matter spike, relative to the host central SMBHs, which defines the parameter space LISA can constrain.}, archive = {J_ApJ}, author = {Wei-Xiang Feng and Simeon Bird and Hai-Bo Yu}, doi = {10.3847/1538-4357/adda2f}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {151}, shortjournal = {The Astrophys. J.}, title = {Gravitational waves from primordial black hole dark matter spikes}, volume = {986}, year = {2025}, }
• (2025). Origin of the shell structure in the primary outflow from IRAS 15398−3359. ApJ, 986(2), 150. (www)

  @article{ , abstract = {IRAS 15398−3359, a Class 0 protostar in the Lupus I star-forming region, is associated with three generations of outflows. The primary outflow, i.e., the most recent one, shows an internal structure named the "shell structure" in the near-infrared emission map. The shell structure is also seen in the emission lines of CO, H 2 CO, and other species. We find a similar structure in an underexpanded jet produced in aerodynamics and other engineering applications. A high-pressure gas ejected through a nozzle expands to form a supersonic flow. When the pressure of the ejected gas becomes lower than that of the ambient gas, the jet is compressed to form a shock wave. The shock-heated gas expands again to form substructures along the jet. We examine the similarity between the primary outflow of IRAS 15398−3359 and the industrial underexpanded jet and the possibility that the shell structure of the former is due to repeated expansion and compression in the direction perpendicular to the jet propagation.}, archive = {J_ApJ}, author = {Tomoyuki Hanawa and Yuki Okoda and Yao-Lun Yang and Nami Sakai}, doi = {10.3847/1538-4357/addac0}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {150}, shortjournal = {The Astrophys. J.}, title = {Origin of the shell structure in the primary outflow from IRAS 15398−3359}, volume = {986}, year = {2025}, }
• (2025). X-ray and infrared analysis on a faint polar RX j1745.5-2905. ApJ, 986(2), 149. (www)

  @article{ , abstract = {RX J1745.5-2905 is a faint and distant polar below the period gap. It was observed intensively in X-ray by Chandra, and its X-ray data reveal frequent brightness transitions between low and high states like we found in the prototype star AM Her. The X-ray radiation is consistent with a typical depiction of magnetic accretion. Although it was detected in X-rays, its counterpart in other bands has not been observed so far. We retrieved all public data and found that Hubble Space Telescope (HST) cached RX J1745.5-2905 in the infrared band (F139M). The infrared photometry confirms its normal behaviors in the low-energy band. Our analysis indicates that the combination of Chandra and HST can help us reach far-distant polars and that the long-term behavior of X-ray sources can help us identify the nature of these sources in the Galactic center.}, archive = {J_ApJ}, author = {Qishan Wang and Xiaohui Fang and Shengbang Qian}, doi = {10.3847/1538-4357/addb43}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {149}, shortjournal = {The Astrophys. J.}, title = {X-ray and infrared analysis on a faint polar RX j1745.5-2905}, volume = {986}, year = {2025}, }
• (2025). Chemical abundances of early quiescent galaxies: New observations and modeling impacts. ApJ, 986(2), 148. (www)

  @article{ , abstract = {Recent stellar chemical abundance measurements of a handful of z ∼ 2 quiescent galaxies have suggested these galaxies exhibit a remarkably strong α -enhancement compared to their local and intermediate-redshift counterparts. This apparent chemical evolution following quenching suggests that even the innermost regions of massive early-type galaxies may have experienced substantial mixing of stars in mergers, challenging a purely inside-out growth model. However, larger samples are needed to determine whether a high α -enhancement ([Mg/Fe] ≈0.5) is common in z ∼ 2 quiescent galaxies, and a comparative analysis is needed to determine whether it is consistently inferred using different stellar population synthesis models. We report age and stellar chemical abundance measurements for a sample of four gravitationally lensed quiescent galaxies at z ∼ 2.1–2.65 based on Magellan/FIRE spectroscopy. For three of these galaxies we constrain the α -enhancement, and in two cases we measure high values comparable to earlier results when the spectra are analyzed consistently. We also find that the choice of modeling approach can exert a significant effect on the measured abundances. This model dependence can be partly, but not entirely, explained by the complex abundance patterns of α -elements in galaxies, which has been observed at lower redshifts and in one z ∼ 2 quiescent galaxy. Our investigation highlights the importance of independently varying abundance of α -elements when fitting the spectra of such galaxies. Observations with JWST will soon deliver precise and spatially resolved abundances of these and other quiescent galaxies at cosmic noon, opening a new window into their evolution.}, archive = {J_ApJ}, author = {Marziye Jafariyazani and Andrew B. Newman and Bahram Mobasher and Sirio Belli and Richard S. Ellis and Andreas L. Faisst}, doi = {10.3847/1538-4357/addbdc}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {148}, shortjournal = {The Astrophys. J.}, title = {Chemical abundances of early quiescent galaxies: New observations and modeling impacts}, volume = {986}, year = {2025}, }
• (2025). EDEN: Exploring disks embedded in N-body simulations of milky way–mass halos from symphony. ApJ, 986(2), 147. (www)

  @article{ , abstract = {We investigate the impact of galactic disks on the tidal stripping of cold dark matter subhalos within Milky Way (MW)-mass halos ( M vir ∼ 10 12 M ⊙ ) using a new simulation suite, EDEN. By re-simulating 45 MW-mass zoomed-in halos from the N-body Symphony compilation with embedded disk potentials, which evolve according to star formation histories predicted by the U niverse M achine model, we self-consistently tie disk growth to halo accretion rate and significantly expand the range of disk masses and formation histories studied. We use the particle-tracking-based subhalo finder Symfind to enhance the robustness of subhalo tracking. We find that disks near the median disk-to-halo mass ratio of our sample ( M *,Disk / M vir,host = 2%) reduce subhalo peak mass functions within 100 kpc by about 10% for peak masses above 10 8 M ⊙ . Heavier, MW/M31-like disks ( M *,Disk / M vir,host ≳ 5%) lead to a reduction of more than 40%. Subhalo abundance suppression is more pronounced near halo centers, with particularly enhanced stripping for subhalos accreted over 8 Gyr ago on orbits with pericenters <100 kpc. Suppression is further amplified when disk mass is increased within fixed halo and disk assembly histories. In all cases, the suppression we measure should be interpreted as stripping below the mass resolution limit rather than complete subhalo disruption. This study reshapes our understanding of the MW's impact on its satellites, suggesting it strips subhalos more efficiently than typical MW-mass galaxies due to its larger disk-to-halo mass ratio and earlier disk formation.}, archive = {J_ApJ}, author = {Yunchong Wang and Philip Mansfield and Ethan O. Nadler and Elise Darragh-Ford and Risa H. Wechsler and Daneng Yang and Hai-Bo Yu}, doi = {10.3847/1538-4357/adcfa3}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {147}, shortjournal = {The Astrophys. J.}, title = {EDEN: Exploring disks embedded in N-body simulations of milky way–mass halos from symphony}, volume = {986}, year = {2025}, }
• (2025). Size–Frequency distribution of terrestrial leftover planetesimals and S-complex implanted asteroids. ApJ, 986(2), 146. (www)

  @article{ , abstract = {The isotopic composition of meteorites linked to S-complex asteroids has been used to suggest that these asteroids originated in the terrestrial planet's region, i.e., within 1.5 au, and later got implanted into the main asteroid belt (MAB). Dynamical models of planet formation support this view. Yet it remains to be demonstrated whether the currently observed size–frequency distribution (SFD) of S-complex bodies in the MAB can be reproduced via this implantation process. Here we studied the evolution of the SFD of planetesimals during the accretion of terrestrial planets with the code LIPAD self-consistently accounting for growth and fragmentation of planetesimals. In our simulations we vary the initial surface density of planetesimals, the gaseous disk lifetime, and the power slope of the initial planetesimals' SFD. We compared the final SFDs of leftover planetesimals in the terrestrial planet region with the SFD of observed S-complex MAB objects ( D > 100 km). We found that the SFDs of our planetesimal populations and that of S-complex MAB objects show very similar cumulative power index (i.e., q ≈ 3.15 in N (> D ) ∝ D − q ) for slopes in the diameter range 100 km < D < 400 km by the end of our simulations. Our results support the hypothesis of S-complex MAB implantation from the terrestrial planet forming region, assuming implantation is size independent, and imply that implantation efficiency is smaller than { \mathcal O } (10 –2 –10 –4 ) to avoid overimplantation of (4) Vesta-sized objects or larger.}, archive = {J_ApJ}, author = {Rogerio Deienno and André Izidoro and David Nesvorný and William F. Bottke and Fernando Roig and Simone Marchi}, doi = {10.3847/1538-4357/adccbb}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {146}, shortjournal = {The Astrophys. J.}, title = {Size–Frequency distribution of terrestrial leftover planetesimals and S-complex implanted asteroids}, volume = {986}, year = {2025}, }
• (2025). DIISC-V: Variations in hα-to-FUV star formation rate ratios across star-forming regions in nearby galaxies. ApJ, 986(2), 145. (www)

  @article{ , abstract = {We present the variations in far-ultraviolet (FUV) and H α star formation rates (SFR), SFR UV and SFR H α , respectively, at subkiloparsec scales in 11 galaxies as part of the Deciphering the Interplay between the Interstellar Medium, Stars, and the Circumgalactic medium survey. Using archival GALEX FUV imagery and H α +[N ii ] narrowband images obtained with the Vatican Advanced Technology Telescope, we detect a total of 1335 (FUV-selected) and 1474 (H α -selected) regions of recent high-mass star formation, respectively. We find the H α -to-FUV SFR ratios tend to be lower primarily for FUV-selected regions, where SFR H α generally underestimates the SFR by an average factor of 2–3, for SFR < 10 −4 M ⊙ yr −1 . In contrast, the SFRs are generally observed to be consistent for H α -selected regions. This discrepancy arises from morphological differences between the two indicators. Extended FUV morphologies and larger areas covered by FUV-only regions, along with decreasing overlap between FUV clumps and compact H ii regions with R / R 25 suggest that stochastic sampling of the initial mass function may be more pronounced in the outer regions of galaxies. Our observed H α -to-FUV SFR ratios are also consistent with stochastic star formation model predictions. However, using larger apertures that include diffuse FUV emission results in an offset of 1 dex between SFR H α and SFR UV , suggesting that the observed low H α -to-FUV SFR ratios in galaxies are likely caused by diffuse FUV emission, which can contribute ∼60%–90% to the total FUV flux.}, archive = {J_ApJ}, author = {Mansi Padave and Sanchayeeta Borthakur and Rolf A. Jansen and David A. Thilker and Jacqueline Monkiewicz and Rogier A. Windhorst}, doi = {10.3847/1538-4357/adce7b}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {145}, shortjournal = {The Astrophys. J.}, title = {DIISC-V: Variations in hα-to-FUV star formation rate ratios across star-forming regions in nearby galaxies}, volume = {986}, year = {2025}, }
• (2025). Asteroseismology of metal-poor red giants observed by TESS. ApJ, 986(2), 144. (www)

  @article{ , abstract = {Galactic archeology has long been limited by a lack of precise masses and ages for metal-poor stars in the Milky Way's thick disk. However, with TESS providing a growing number of photometric observations, it is possible to calculate masses and ages for more solar-like oscillators than ever using asteroseismology. We have used the pySYD pipeline to determine global asteroseismic parameters, and calculated the masses and ages of 506 metal-poor ([M/H] < −0.5) red giants observed by TESS. Our findings appear to show metallicity-dependent mass loss on the upper red giant branch and identify a set of "young" high- α stars that have been detected in other studies. We also find that 32.6% of the metal-poor stars appear to be binary interaction products, and four stars with stellar ages that could be from the Gaia-Enceladus/Sausage system. In combination with existing ages from Kepler/K2, these data can be compared to galactic evolution models to better determine the formation history of the Galaxy.}, archive = {J_ApJ}, author = {Corin Marasco and Jamie Tayar and David Nidever}, doi = {10.3847/1538-4357/add0b4}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {144}, shortjournal = {The Astrophys. J.}, title = {Asteroseismology of metal-poor red giants observed by TESS}, volume = {986}, year = {2025}, }
• (2025). Spatially resolved star formation rate and dust attenuation of nearby galaxies from CALIFA, GALEX, and WISE data. ApJ, 986(2), 143. (www)

  @article{ , abstract = {We study star formation rate (SFR) indicators and dust attenuation of 74 nearby star-forming galaxies on kiloparsec scales, based on GALEX far-ultraviolet (FUV) and WISE mid-infrared (MIR) images with CALIFA optical integral field spectroscopic data. We obtain hybrid SFR indicators by combining the observed FUV and MIR luminosities and calibrate them using the dust-corrected H α luminosity as a reference SFR. The simple linear combination appears to follow well the reference SFR, but the calibration residual shows a significant dependence on the specific SFR (sSFR), which can be removed by employing the combination coefficient or conversion offset that varies with the sSFR. In the plane of gas versus stellar attenuation, the median trend line's slope (≈stellar-to-gas attenuation ratio) changes from 0.44 to 1.0 with increasing attenuation. The differential attenuation, defined as the deviation of stellar attenuation from the median trend line, is strongly correlated with the SFR surface density and sSFR, compatible with the two-component dust model. The differential attenuation seems to be affected by both local and global factors.}, archive = {J_ApJ}, author = {Jong Chul Lee and Joon Hyeop Lee and Hyunjin Jeong and Mina Pak and Sree Oh}, doi = {10.3847/1538-4357/add1d6}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {143}, shortjournal = {The Astrophys. J.}, title = {Spatially resolved star formation rate and dust attenuation of nearby galaxies from CALIFA, GALEX, and WISE data}, volume = {986}, year = {2025}, }
• (2025). Multipoint observations and modeling of the 2021 november 4 forbush decrease using solar orbiter, CSES-01, and ground-based neutron monitor data. ApJ, 986(2), 142. (www)

  @article{ , abstract = {During their propagation in the heliosphere, interplanetary coronal mass ejections (ICMEs) interact with galactic cosmic ray (GCR) particles, modifying their spectrum and driving anisotropies. We analyze the first large Forbush decrease (FD) of Solar Cycle 25 on 2021 November 3–5 by using multipoint in situ observations and neutron monitors to study the association between FD characteristics and ICME. We use the Grad–Shafranov reconstruction to infer the magnetic field configuration of the ICME. We model the neutron monitor response through primary spectrum and anisotropy. The primary spectrum is parameterized with the force-field approximation and the anisotropy is modeled through a spherical harmonic expansion. We optimize the model parameters during the FD by using ground-based observations provided by the worldwide neutron-monitor network. The model's results are compared with space-based measurements of the differential proton flux measured by the HEPD-01 detector on board the CSES-01 satellite and of the integral counts of both the High-Energy Particle Detector (HEPD-01) and the High Energy Telescope on board the Solar Orbiter. Anisotropy develops during the ICME passage, within the magnetic flux rope (MFR) and is found to be bidirectional. The force-field parameterization of the primary GCR fluxes based on ground-based measurements is found to be in very good agreement with spacecraft observations in the sub-GeV range. The GCR anisotropy obtained by fitting the model to ground-based observations is consistent with interplanetary magnetic field observations. The results suggest that the local magnetic field has a substantial axial component that is aligned to the MFR axis, and determines the GCR anisotropy at the typical neutron monitor energies.}, archive = {J_ApJ}, author = {Simone Benella and Monica Laurenza and Matteo Martucci and David Ruffolo and Qiang Hu and Georgios Nicolaou and Christopher J. Owen and Mirko Stumpo and Christina Plainaki and Francesco Palma and Mirko Piersanti and Matteo Sorbara and Alessandro Sotgiu and Roberta Sparvoli}, doi = {10.3847/1538-4357/add329}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {142}, shortjournal = {The Astrophys. J.}, title = {Multipoint observations and modeling of the 2021 november 4 forbush decrease using solar orbiter, CSES-01, and ground-based neutron monitor data}, volume = {986}, year = {2025}, }
• (2025). Exploring contact binaries: Observational analysis of four w uma binaries using photometry and spectroscopy. ApJ, 986(2), 141. (www)

  @article{ , abstract = {We present the multiband photometric and low-resolution spectroscopic analysis of four W Ursae Majoris eclipsing binaries (EWs)—J080510.1+141528 (hereinafter as J0805a), J080516.3+143138 (hereinafter as J0805b), J143358.7+053953 (hereinafter as J1433), and J143458.4+054143 (hereinafter as J1434). The multiband ground based photometric data are collected using the 1.3 m Devasthal Fast Optical Telescope, while we also make use of Transiting Exoplanet Survey Satellite (TESS) photometric observations. The spectroscopic analysis is based on the low-resolution observations by the 4 m Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST). The ephemerides of these systems are updated using the photometric data from TESS and other photometric surveys. The system J0805b shows a secular change in the orbital period with a period change rate of 4.2 (±0.1) × 10 −7 days per year, while the orbital period change rate for J1433 is calculated as −1.1 (±0.1) × 10 −6 days per year. The mass-transfer rate for J0805b is found to be d M 1 / d t = −1.56(±0.07) × 10 −6 M ⊙ yr −1 and dM 1 / dt = −7.95(±0.87) × 10 −7 M ⊙ yr −1 for J1433. All the systems have inclination > 79 ∘ except J1433, which has an inclination of 72 \mathop{.}\limits^{\unicode{x000b0}} 8. The mass ratios (less massive to more massive component) for these targets are <0.5. All the systems except J0805b are A-subtype contact binaries. The absolute parameters of the systems are determined using Gaia DR3 parallax and reddening information. The LAMOST spectra are analyzed using the spectral subtraction technique. A small excess emission is detected for J1433 in H α and H β region. The systems are plotted on a Hertzsprung–Russell diagram and compared with previously studied systems. The mass ratio versus radius ratio relation is also investigated for these systems.}, archive = {J_ApJ}, author = {A. Panchal and Y. C. Joshi and V. Joshi and A. Chakraborty}, doi = {10.3847/1538-4357/add34d}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {141}, shortjournal = {The Astrophys. J.}, title = {Exploring contact binaries: Observational analysis of four w uma binaries using photometry and spectroscopy}, volume = {986}, year = {2025}, }
• (2025). Martian dynamo change at ∼4.1 ga: Evidence from the magnetic measurements of the iota crater. ApJ, 986(2), 140. (www)

  @article{ , abstract = {The Martian dynamo evolution is critical for understanding Mars's interior structure, thermal evolution, and climate change. It has been inferred to shut down at ∼4.1–4.0 Ga based on the magnetic signatures of large impact craters, but be present at ∼3.9 Ga and ∼3.7 Ga from the paleomagnetic studies and magnetic fields above volcanic units. Here, we investigate the magnetic signatures of the Iota crater, located inside the CT3-G area with a centrally strong magnetic anomaly. The Iota crater shows a weak central magnetic field with an inside-outside strength ratio of 0.39. Forward modeling is established to explore the relationship between the magnetic field signatures of craters and the magnetization caused by impact. The results show that the average magnetization of the retained materials beneath the Iota crater is about 20% of the maximum of the surroundings, indicating that the dynamo strength at that time became weak. The magnetic signatures of Iota and CT3-G reveal that the Martian dynamo decayed at ∼4.1 Ga, but did not stop completely.}, archive = {J_ApJ}, author = {Kuixiang Zhang and Can Huang and Zongyu Yue and Hao Luo and Jipeng Qin and Dongke Chen and Junyu Zhao and Yasong Ge and Aimin Du}, doi = {10.3847/1538-4357/add3f3}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {140}, shortjournal = {The Astrophys. J.}, title = {Martian dynamo change at ∼4.1 ga: Evidence from the magnetic measurements of the iota crater}, volume = {986}, year = {2025}, }
• (2025). Cracking the relation between mass and 1P-star fraction of globular clusters. III. initial distributions of in situ and ex situ clusters. ApJ, 986(2), 139. (www)

  @article{ , abstract = {Galactic globular clusters consist of two main stellar populations, the pristine (1P) and polluted (2P) stars. The fraction of 1P stars in clusters, F 1P , is a decreasing function of the present-day cluster mass, m prst . The information about cluster formation it contains has yet to be unlocked. Paper I demonstrated that the observed distribution ( m prst , F 1P ) of Galactic globular clusters can result from a pristine-star fraction that is inversely proportional to their birth mass, m ecl . This relation was then calibrated with a fixed stellar mass threshold for 2P-star formation, m th , i.e., F 1 P = m th / m ecl . We now estimate the masses m init of Galactic globular clusters as they start their long-term gas-free evolution in the Galaxy and we map their behavior in the ( m init , F 1P ) space. Several dissolution timescales are tested (with and without primordial mass segregation), each yielding its own initial cluster distribution ( m init , F 1P ). The ( m init , F 1P ) distributions are mapped according to cluster origin, with the emphasis on the Disk, Low-Energy and Gaia-Enceladus cluster groups of D. Massari et al. All three initial distributions ( m init , F 1P ) are more compact than their present-day counterparts since dynamical evolution scatters clusters in the F 1P versus cluster-mass space. The Disk initial distribution is the tightest one and potential reasons for this are discussed. Its power-law representation allows us to generalize the initial mass threshold of Paper I and prompts us to represent the cluster (mass, F 1P ) distribution in a log–log space. No evidence is found suggesting that, initially, the pristine-star fraction of globular clusters depends on their metallicity on top of their mass.}, archive = {J_ApJ}, author = {Geneviève Parmentier}, doi = {10.3847/1538-4357/add40c}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {139}, shortjournal = {The Astrophys. J.}, title = {Cracking the relation between mass and 1P-star fraction of globular clusters. III. initial distributions of in situ and ex situ clusters}, volume = {986}, year = {2025}, }
• (2025). A MARVEL-ous study of how well galaxy shapes reflect dark matter halo shapes in cold dark matter simulations. ApJ, 986(2), 138. (www)

  @article{ , abstract = {We present a 3D shape analysis of both dark matter (DM) and stellar matter (SM) in simulated dwarf galaxies to determine whether stellar shape traces DM shape. Using 80 central and satellite dwarf galaxies from three simulation suites ("Marvelous Massive Dwarfs," "Marvelous Dwarfs," and the "DC Justice League") spanning stellar masses of 10 6 –10 10 M ⊙ , we measure 3D shapes through the moment of inertia tensor at twice the effective radius to derive axis ratios ( C / A and B / A ) and triaxiality. We find that stellar shape does follow DM halo shape for our dwarf galaxies. However, the presence of a stellar disk in more massive dwarfs ( M * ≳ 10 7.5 M ⊙ ) pulls the distribution of stellar C / A ratios to lower values, while in lower-mass galaxies the gravitational potential remains predominantly shaped by DM. Similarly, stellar triaxiality generally tracks DM triaxiality, with this relationship being particularly strong for nondisky galaxies and weaker in disky systems. These correlations are reinforced by strong alignment between the SM and DM axes, particularly in disk galaxies. Further, we find no detectable difference in either SM or DM shapes when comparing two different supernova feedback implementations, demonstrating that shape measurements are robust to different implementations of baryonic feedback in dwarf galaxies. We also observe that a dwarf galaxy's shape is largely unperturbed by recent mergers. This comprehensive study demonstrates that stellar shape measurements can serve as a reliable tool for inferring DM shapes in dwarf galaxies.}, archive = {J_ApJ}, author = {Blake Keith and Ferah Munshi and Alyson M. Brooks and Jordan Van Nest and Anna Engelhardt and Akaxia Cruz and Ben Keller and Thomas Quinn and James Wadsley}, doi = {10.3847/1538-4357/add40d}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {138}, shortjournal = {The Astrophys. J.}, title = {A MARVEL-ous study of how well galaxy shapes reflect dark matter halo shapes in cold dark matter simulations}, volume = {986}, year = {2025}, }
• (2025). Unprecedented continuum time delay variation phenomenon in an active supermassive black hole. ApJ, 986(2), 137. (www)

  @article{ , abstract = {Resolving the accretion disks and broad-line regions of active galactic nuclei (AGNs) can probe the physics behind supermassive black hole (SMBH) fueling and weigh SMBHs. With time-domain observations, the reverberation mapping (RM) technique measures time delays between different light curves, probing the AGN inner structures that are otherwise often too compact to resolve spatially with current facilities. Theoretically, the SMBH accretion disk structure does not evolve over decades. Here we report the significant variations in the continuum time delays of NGC 4151. In the high-flux state, our high-cadence (∼2 days) spectroscopy reveals that continuum time delays are 3.{8}_{-1.0}^{+1.8} times larger than those in the low-flux state and 14.9 ± 2.0 times longer than the classical standard thin-disk prediction. Notably, the continuum time delays can be comparable to the time delay between H β and the 5100 Å continuum, and the latter is commonly used to calculate the BLR sizes. Hence, the BLR sizes are underestimated if the continuum time delays are not considered, which introduces ∼0.3 dex systematic uncertainties on RM SMBH masses. Our findings underscore that simultaneous continuum and BLR RMs are vital for better deciphering the SMBH accretion and mass function.}, archive = {J_ApJ}, author = {Shuying Zhou and Mouyuan Sun and Hai-Cheng Feng and Sha-Sha Li and Yongquan Xue and Jun-Xian Wang and Zhen-Yi Cai and Jin-Ming Bai and Danyang Li and Hengxiao Guo and H. T. Liu and Kai-Xing Lu and Jirong Mao and Marcin Marculewicz and Jian-Guo Wang}, doi = {10.3847/1538-4357/add468}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {137}, shortjournal = {The Astrophys. J.}, title = {Unprecedented continuum time delay variation phenomenon in an active supermassive black hole}, volume = {986}, year = {2025}, }
• (2025). Submillimeterwave spectroscopy of and interstellar search for nitrosomethane: CH3NO. ApJ, 986(2), 136. (www)

  @article{ , abstract = {New measurements of nitrosomethane (CH 3 NO), a formamide isomer, were done up to 660 GHz. The molecule exhibits internal rotation motion from the CH 3 group, and therefore the analysis with a dedicated rho-axis method code, RAM36, was used. A total of 2035 lines for v t = 0 and 1 states of A and E symmetries were fitted with an rms deviation of 41.1 kHz, with the maximum quantum numbers values J = 30 and K a = 15. Using these new data, CH 3 NO was searched in the cold dark cloud Taurus Molecular Cloud 1 as well as the high mass star-forming regions Sgr B2(N) and NGC 6334I. CH 3 NO was not observed in any of the sources, 3 σ column density upper limits were determined, and we discuss the implications for the chemistry of CH 3 NO in the interstellar medium. The accurate spectroscopic prediction of its spectra provided in this work will allow astronomers to continue the search of CH 3 NO in other interstellar sources.}, archive = {J_ApJ}, author = {Laurent Margulès and Zachary T. P. Fried and Alex N. Byrne and Brett A. McGuire and Luyao Zou and Roman A. Motiyenko and J.-C. Guillemin}, doi = {10.3847/1538-4357/add47f}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {136}, shortjournal = {The Astrophys. J.}, title = {Submillimeterwave spectroscopy of and interstellar search for nitrosomethane: CH3NO}, volume = {986}, year = {2025}, }
• (2025). Detection prospects of electromagnetic signatures from OGLE-2011-BLG-0462. ApJ, 986(2), 135. (www)

  @article{ , abstract = {Stellar-mass isolated black holes wandering in the interstellar medium are expected to be abundant in our Galaxy. Recently, an isolated free floating black hole (IsoBH), OGLE-2011-BLG-0462, was unambiguously discovered using astrometric microlensing. We examine prospects for detecting electromagnetic signatures from an accretion flow surrounding the IsoBH. The accretion rate onto the IsoBH should be highly sub-Eddington, which leads to formation of a hot accretion flow. In this paper, we evaluate the detectability of electromagnetic signals from the hot accretion flows in two accretion states: magnetically arrested disk (MAD) and classical radiatively inefficient accretion flows (RIAFs). For the MAD scenario, we find that the optical, infrared, and X-ray signals can be detectable by the current best facilities, such as the Hubble Space Telescope, JWST, and Chandra, if the IsoBH is in a warm neutral medium. In contrast, for the classical RIAF scenario, the optical and X-ray emissions are weaker than the MAD scenario, leading to unobservable signals for a typical parameter set. Future follow-up observations of OGLE-2011-BLG-0462 will provide a good test for theories of accretion processes.}, archive = {J_ApJ}, author = {Shigeo S. Kimura and Lena Murchikova and Kailash C. Sahu}, doi = {10.3847/1538-4357/add52c}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {135}, shortjournal = {The Astrophys. J.}, title = {Detection prospects of electromagnetic signatures from OGLE-2011-BLG-0462}, volume = {986}, year = {2025}, }
• (2025). Forming prominences accounting for partial ionization effects. ApJ, 986(2), 134. (www)

  @article{ , abstract = {One of the most striking structures in the solar atmosphere are prominences, predominantly coronal structures, with thermodynamic conditions that vary from chromospheric internally to the corona that surrounds them. These structures play an important role in the energy transfer between all layers of the atmosphere. Although mostly studied as a fully ionized plasma, prominences are, in fact, composed of partially ionized plasma. We do not yet fully understand the extent to which the two-fluid plasma-neutral properties play a role in the evolution of these coronal structures. In this work, we explore for the very first time how prominence formation and growth in a coronal loop evolve in a two-fluid setting. We used MPI-AMRVAC to study the evaporation–condensation process, where we consider radiative cooling, thermal conduction, and localized heating in a coronal loop in a fully stratified atmosphere. We report on the differences the two-fluid plasma brings into the prominence evolution and more specifically in the period after the dynamic formation process finishes. Furthermore, we highlight the role it plays during the linear and the nonlinear phases of the evolution. We find pronounced two-fluid effects in shocks that appear with the first complete condensation and confirm decoupling effects in the prominence–corona transition region on the order of 100 m s −1 , consistent with observations.}, archive = {J_ApJ}, author = {V. Jerčić and B. Popescu Braileanu and R. Keppens}, doi = {10.3847/1538-4357/add6aa}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {134}, shortjournal = {The Astrophys. J.}, title = {Forming prominences accounting for partial ionization effects}, volume = {986}, year = {2025}, }
• (2025). Cosmology with one galaxy: Autoencoding the galaxy properties manifold. ApJ, 986(2), 133. (www)

  @article{ , abstract = {Cosmological simulations like CAMELS and IllustrisTNG characterize hundreds of thousands of galaxies using various internal properties. Previous studies have demonstrated that machine learning can be used to infer the cosmological parameter Ω m from the internal properties of even a single randomly selected simulated galaxy. This ability was hypothesized to originate from galaxies occupying a low-dimensional manifold within a higher-dimensional galaxy property space, which shifts with variations in Ω m . In this work, we investigate how galaxies occupy the high-dimensional galaxy property space, particularly the effect of Ω m and other cosmological and astrophysical parameters on the putative manifold. We achieve this by using an autoencoder with an information-ordered bottleneck, a neural layer with adaptive compression, to perform dimensionality reduction on individual galaxy properties from CAMELS simulations, which are run with various combinations of cosmological and astrophysical parameters. We find that for an autoencoder trained on the fiducial set of parameters, the reconstruction error increases significantly when the test set deviates from fiducial values of Ω m and A SN1 , indicating that these parameters shift galaxies off the fiducial manifold. In contrast, variations in other parameters such as σ 8 cause negligible error changes, suggesting galaxies shift along the manifold. These findings provide direct evidence that the ability to infer Ω m from individual galaxies is tied to the way Ω m shifts the manifold. Physically, this implies that parameters like σ 8 produce galaxy property changes resembling natural scatter, while parameters like Ω m and A SN1 create unsampled properties, extending beyond the natural scatter in the fiducial model.}, archive = {J_ApJ}, author = {Amanda Lue and Shy Genel and Marc Huertas-Company and Francisco Villaescusa-Navarro and Matthew Ho}, doi = {10.3847/1538-4357/add724}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {133}, shortjournal = {The Astrophys. J.}, title = {Cosmology with one galaxy: Autoencoding the galaxy properties manifold}, volume = {986}, year = {2025}, }
• (2025). Truncated star formation and ram pressure stripping in the coma cluster. ApJ, 986(2), 132. (www)

  @article{ , abstract = {We use 45 galaxies from the Mapping Nearby Galaxies at Apache Point Observatory survey to study the physical drivers of star formation quenching in the Coma Cluster. We measure specific star formation rate (sSFR) radial profiles for the Coma sample as well as a control sample of noncluster field galaxies. We find that compared to the control sample, galaxies within the Coma Cluster have sSFR profiles that fall off more steeply with galactocentric radius. We then apply a toy model based on slow-then-rapid quenching via ram pressure stripping. We find that this model is able to reproduce the difference in sSFR profiles between field and Coma galaxies. These results demonstrate that ram pressure stripping plays a significant role in quenching star formation in the nearest massive galaxy cluster.}, archive = {J_ApJ}, author = {Ariel O. Broderick and Ian D. Roberts and Michael J. Hudson}, doi = {10.3847/1538-4357/add739}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {132}, shortjournal = {The Astrophys. J.}, title = {Truncated star formation and ram pressure stripping in the coma cluster}, volume = {986}, year = {2025}, }
• (2025). Origins of persistence in energetic neutral atom time series from IBEX. ApJ, 986(2), 131. (www)

  @article{ , abstract = {Recently, we studied the persistence of energetic neutral atom (ENA) fluxes recorded by the Interstellar Boundary Explorer (IBEX) from the north and south polar regions by examining the correct time order for the 14 yr of IBEX data. Here, we further explore the origins of this persistence by comparing the time series of the ENA fluxes obtained from the near-Earth with the time series of the solar wind flow pressure at 1 au. To this end, we employ the detrended fluctuation analysis (DFA), a modern technique for characterizing the persistence of a time series. We show that even when removing all periodic trends from the flux time series, the remaining fluctuations exhibit DFA exponents compatible with those found for the solar wind pressure time series, indicating a causal relation between the two time series. The analysis was performed separately for the north and south poles, characterizing their anisotropy. Finally, we apply the DFA technique to the ENA time series of the polar spectral indices, an exponent related to the thermodynamic kappa and the stationary state of the source protons. This reveals that the plasma proton thermodynamics in both north and south polar regions share the same DFA persistence, despite the hemispheric asymmetry between the generated ENAs.}, archive = {J_ApJ}, author = {N. V. Sarlis and G. Livadiotis and D. J. McComas and M. Alimaganbetov and N. A. Schwadron}, doi = {10.3847/1538-4357/addb4a}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {131}, shortjournal = {The Astrophys. J.}, title = {Origins of persistence in energetic neutral atom time series from IBEX}, volume = {986}, year = {2025}, }
• (2025). Another piece to the puzzle: Radio detection of a JWST-detected active galactic nucleus candidate. ApJ, 986(2), 130. (www)

  @article{ , abstract = {Radio observations can provide crucial insight into the nature of a new abundant and mysterious population of dust-reddened active galactic nuclei (AGN) candidates discovered by the James Webb Space Telescope (JWST), including "Little Red Dots." In this study, we search for radio bright sources in a large sample of ∼700 JWST-discovered AGN candidates ( z ∼ 2–11) in the 0.144–3 GHz frequency range, utilizing deep radio imaging in the Cosmic Evolution Survey and Great Observatories Origins Deep Survey North and South. Only one source, PRIMER-COS 3866 at z = 4.66, is significantly detected in our radio surveys, which has been previously identified as an X-ray AGN. Its radio properties are consistent with both an AGN and star formation origin with a spectral index of \alpha =-0.7{6}_{-0.09}^{+0.11} , radio-loudness of R ≈ 0.5, and brightness temperature limit of T b ≳ 10 3 K. Our stacking results of both spectroscopically and photometrically selected AGN candidates yield nondetections in all fields, with 3 σ limits of L 1.4 GHz < 8.6 × 10 39 erg s −1 (spectroscopic sample) and L 1.3 GHz < 1.3 × 10 39 erg s −1 (photometric sample). We demonstrate that these results are still consistent with expectations from the empirical L X – L H α and L X – L R correlations established for local AGN. We argue that current radio observations in these studied fields have insufficient depth to claim JWST-discovered AGN candidates are radio weak. We project that future surveys carried out by the Square Kilometer Array and Next Generation Very Large Array should be able to obtain significant detections within a few hours, providing crucial measurements of their brightness temperature, which would allow for distinguishing between AGN and starburst-driven origins of this new abundant population.}, archive = {J_ApJ}, author = {Anniek J. Gloudemans and Kenneth J. Duncan and Anna-Christina Eilers and Emanuele Paolo Farina and Yuichi Harikane and Kohei Inayoshi and Erini Lambrides and Eleni Vardoulaki}, doi = {10.3847/1538-4357/adddb9}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {130}, shortjournal = {The Astrophys. J.}, title = {Another piece to the puzzle: Radio detection of a JWST-detected active galactic nucleus candidate}, volume = {986}, year = {2025}, }
• (2025). COZMIC. III. cosmological zoom-in simulations of self-interacting dark matter with suppressed initial conditions. ApJ, 986(2), 129. (www)

  @article{ , abstract = {We present eight cosmological dark matter (DM)-only zoom-in simulations of a Milky Way–like system that include suppression of the linear matter power spectrum P ( k ), and/or velocity-dependent DM self-interactions, as the third installment of the COZMIC suite. We consider a model featuring a massive dark photon that mediates DM self-interactions and decays into massless dark fermions. The dark photon and dark fermions suppress linear matter perturbations, resulting in dark acoustic oscillations in P ( k ), which ultimately affect dwarf galaxy scales. The model also features a velocity-dependent elastic self-interaction between DM particles (SIDM), with a cross section that can alleviate small-scale structure anomalies. For the first time, our simulations test the impact of P ( k ) suppression on gravothermal evolution in an SIDM scenario that leads to core collapse in (sub)halos with present-day virial masses below ≈10 9 M ⊙ . In simulations with P ( k ) suppression and self-interactions, the lack of low-mass (sub)halos and the delayed growth of structure reduce the fraction of core-collapsed systems relative to SIDM simulations without P ( k ) suppression. In particular, P ( k ) suppression that saturates current warm DM constraints almost entirely erases core collapse in isolated halos. Models with less extreme P ( k ) suppression produce core collapse in ≈20% of subhalos and ≈5% of isolated halos above 10 8 M ⊙ , and also increase the abundance of extremely low-concentration isolated low-mass halos relative to SIDM. These results reveal a complex interplay between early and late-Universe DM physics, revealing new discovery scenarios in the context of upcoming small-scale structure measurements.}, archive = {J_ApJ}, author = {Ethan O. Nadler and Rui An and Daneng Yang and Hai-Bo Yu and Andrew Benson and Vera Gluscevic}, doi = {10.3847/1538-4357/adce82}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {129}, shortjournal = {The Astrophys. J.}, title = {COZMIC. III. cosmological zoom-in simulations of self-interacting dark matter with suppressed initial conditions}, volume = {986}, year = {2025}, }
• (2025). COZMIC. II. cosmological zoom-in simulations with fractional non-CDM initial conditions. ApJ, 986(2), 128. (www)

  @article{ , abstract = {We present 24 cosmological dark matter (DM)-only zoom-in simulations of a Milky Way analog with initial conditions appropriate for scenarios where non-cold dark matter (NCDM) is a fraction of the total DM abundance (f-NCDM models) as the second installment of the COZMIC suite. We initialize our simulations using transfer functions, {{ \mathcal T }}_{{\rm{f}}-{\rm{NCDM}}}(k)\equiv \sqrt{{P}_{{\rm{f}}-{\rm{NCDM}}}(k)/{P}_{{\rm{CDM}}}(k)} (where P ( k ) is the linear matter power spectrum), with an initial suppression similar to thermal-relic warm dark matter (WDM) followed by a constant-amplitude plateau. We simulate suppression wavenumbers [22.8, 32.1, 41.8, 52.0, 57.1, 95.3] Mpc −1 , corresponding to thermal-relic WDM masses m WDM ∈ [3, 4, 5, 6, 6.5, 10] keV, and plateau amplitudes δ ∈ [0.2, 0.4, 0.6, 0.8]. We model the subhalo mass function in terms of the suppression wave number and δ . Integrating these models into a forward model of the MW satellite galaxy population yields new limits on f-NCDM scenarios, with suppression wavenumbers greater than 46 and 40 Mpc −1 for δ = 0.2 and 0.4, respectively, at 95% confidence. The current data do not constrain δ > 0.4. We map these limits to scenarios where a fraction f WDM of DM behaves as a thermal relic, which yields the following bounds on cosmologies with a mixture of WDM and CDM: m WDM > 3.6, 4.1, 4.6, 4.9, 5.4 keV for f WDM = 0.5, 0.6, 0.7, 0.8, 0.9, respectively, at 95% confidence. The current data do not constrain WDM fractions f WDM < 0.5. Our results affirm that low-mass halo abundances are sensitive to partial suppression in P ( k ), indicating the possibility of using galactic substructure to reconstruct P ( k ) on small scales.}, archive = {J_ApJ}, author = {Rui An and Ethan O. Nadler and Andrew Benson and Vera Gluscevic}, doi = {10.3847/1538-4357/adce83}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {128}, shortjournal = {The Astrophys. J.}, title = {COZMIC. II. cosmological zoom-in simulations with fractional non-CDM initial conditions}, volume = {986}, year = {2025}, }
• (2025). COZMIC. i. cosmological zoom-in simulations with initial conditions beyond cold dark matter. ApJ, 986(2), 127. (www)

  @article{ , abstract = {We present 72 cosmological dark-matter--only N -body zoom-in simulations with initial conditions beyond cold, collisionless dark matter (CDM), as the first installment of the COZMIC suite. We simulate Milky Way (MW) analogs with linear matter power spectra P ( k ) for (i) thermal-relic warm dark matter (WDM) with masses m WDM ∈ [3, 4, 5, 6, 6.5, 10]keV, (ii) fuzzy dark matter (FDM) with masses m FDM ∈ [25.9,69.4, 113, 151, 185, 490] × 10 −22 eV, and (iii) interacting dark matter (IDM) with a velocity-dependent elastic proton scattering cross section σ = σ 0 v n , relative particle velocity scaling n ∈ [2, 4], and dark matter mass m IDM ∈ [10 −4 , 10 −2 , 1] GeV. Subhalo mass function (SHMF) suppression is significantly steeper in FDM versus WDM, while dark acoustic oscillations in P ( k ) can reduce SHMF suppression for IDM. We fit SHMF models to our simulation results and derive new bounds on WDM and FDM from the MW satellite population, obtaining m WDM > 5.9 keV and m FDM > 1.4 × 10 −20 eV at 95% confidence; these limits are ≈10% weaker and 5 × stronger than previous constraints owing to the updated transfer functions and SHMF models, respectively. We estimate IDM bounds for n = 2 ( n = 4) and obtain σ 0 < 1.0 × 10 −27 cm 2 , 1.3 × 10 −24 cm 2 , and 3.1 × 10 −23 cm 2 ( σ 0 < 9.9 × 10 −27 cm 2 , 9.8 × 10 −21 cm 2 , and 2.1 × 10 −17 cm 2 ) for m IDM = 10 −4 , 10 −2 , and 1 GeV, respectively. Thus, future development of IDM SHMF models can improve IDM cross section bounds by up to a factor of ∼20 with current data. COZMIC presents an important step toward accurate small-scale structure modeling in beyond-CDM cosmologies, critical to upcoming observational searches for dark matter physics.}, archive = {J_ApJ}, author = {Ethan O. Nadler and Rui An and Vera Gluscevic and Andrew Benson and Xiaolong Du}, doi = {10.3847/1538-4357/adceef}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {127}, shortjournal = {The Astrophys. J.}, title = {COZMIC. i. cosmological zoom-in simulations with initial conditions beyond cold dark matter}, volume = {986}, year = {2025}, }
• (2025). The rise of faint, red active galactic nuclei at z > 4: A sample of little red dots in the JWST extragalactic legacy fields. ApJ, 986(2), 126. (www)

  @article{ , abstract = {We present a sample of 341 "little red dots" (LRDs) spanning the redshift range z ∼ 2–11 using data from the CEERS, PRIMER, JADES, UNCOVER, and NGDEEP surveys. Unlike past use of color indices to identify LRDs, we employ continuum slope fitting using shifting bandpasses to sample the same rest-frame emission blueward and redward of the Balmer break. This enables the detection of LRDs over a wider redshift range and with less contamination from galaxies with strong breaks that otherwise lack a rising red continuum. The redshift distribution of our sample increases at z < 8 and then undergoes a rapid decline at z ∼ 4.5, which may tie the emergence of these sources to the inside-out growth that galaxies experience during this epoch. We find that LRDs are ∼1 dex more numerous than X-ray- and UV-selected active galactic nuclei (AGN) at z ∼ 5–7. Within our sample, we have identified the first two X-ray-detected LRDs. An X-ray spectral analysis confirms that these AGN are moderately obscured with {\mathrm{log}}\,({N}_{{\rm{H}}}/{{\rm{cm}}}^{2} ) of 23.{3}_{-1.3}^{+0.4} and 22.7{2}_{-0.16}^{+0.13} . Our analysis reveals that reddened AGN emission dominates their rest-optical light, while the rest-UV originates from their host galaxies. We also present NIRSpec observations from the RUBIES survey of 17 LRDs that show broad emission lines consistent with AGN activity. The confirmed AGN fraction of our sample is 71% for sources with F444W < 26.5. In addition, we find three LRDs with blueshifted Balmer absorption features in their spectra, suggesting an outflow of high-density, low-ionization gas from near the central engine of these faint, red AGN.}, archive = {J_ApJ}, author = {Dale D. Kocevski and Steven L. Finkelstein and Guillermo Barro and Anthony J. Taylor and Antonello Calabrò and Brivael Laloux and Johannes Buchner and Jonathan R. Trump and Gene C. K. Leung and Guang Yang and Mark Dickinson and Pablo G. Pérez-González and Fabio Pacucci and Kohei Inayoshi and Rachel S. Somerville and Elizabeth J. McGrath and Hollis B. Akins and Micaela B. Bagley and Rebecca A.A. Bowler and Laura Bisigello and Adam Carnall and Caitlin M. Casey and Yingjie Cheng and Nikko J. Cleri and Luca Costantin and Fergus Cullen and Kelcey Davis and Callum T. Donnan and James S. Dunlop and Richard S. Ellis and Henry C. Ferguson and Seiji Fujimoto and Adriano Fontana and Mauro Giavalisco and Andrea Grazian and Norman A. Grogin and Nimish P. Hathi and Michaela Hirschmann and Marc Huertas-Company and Benne W. Holwerda and Garth Illingworth and Stéphanie Juneau and Jeyhan S. Kartaltepe and Anton M. Koekemoer and Wenxiu Li and Ray A. Lucas and Dan Magee and Charlotte Mason and Derek J. McLeod and Ross J. McLure and Lorenzo Napolitano and Casey Papovich and Nor Pirzkal and Giulia Rodighiero and Paola Santini and Stephen M. Wilkins and L. Y. Aaron Yung}, doi = {10.3847/1538-4357/adbc7d}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {126}, shortjournal = {The Astrophys. J.}, title = {The rise of faint, red active galactic nuclei at z > 4: A sample of little red dots in the JWST extragalactic legacy fields}, volume = {986}, year = {2025}, }
• (2025). Finding massive double-exponential disk galaxies with extended low surface brightness stellar disk: An IllustrisTNG exploration. ApJ, 986(2), 125. (www)

  @article{ , abstract = {We study massive disk galaxies (stellar mass > = 10 11 M ⊙ ) at z = 0 from IllustrisTNG simulation to detect galaxies that contain two exponential stellar disks—a central high surface brightness (HSB) disk surrounded by an extended low surface brightness (LSB) envelope. This is motivated by the observation of several giant LSB galaxies (Malin 1, UGC 1378, UGC 1382 etc), reported in the literature, showing such complex morphology. Studying such systems can help us to understand the mass assembly process and growth of stellar disks in massive galaxies, and thus can shed light on massive galaxy formation and evolution scenarios. We use the high-resolution IllustrisTNG50 data and perform Sérsic plus exponential profile modeling on the idealized, synthetic Sloan Digital Sky Survey g- and r -band images of the massive disk galaxies using GALFIT. We identify seven disk galaxies (12% of the parent sample of disk galaxies) that are best represented by a central Sérsic plus a central HSB disk surrounded by an extended LSB disk. The radial scale lengths of the LSB disk lie in the range of ∼9.7–31.7 kpc, in agreement with that found in the literature. We study the star formation properties of these simulated double-disk galaxies to understand the distribution of these from blue star-forming to red-quenched region. Some of these double-disk galaxies display a characteristic minima in their ( g − r ) color radial profiles. The double-disk galaxies are found to lie within ∼1.5 σ region of the Baryonic Tully–Fisher relation from observation.}, archive = {J_ApJ}, author = {Suchira Sarkar and Kanak Saha}, doi = {10.3847/1538-4357/adcea5}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {125}, shortjournal = {The Astrophys. J.}, title = {Finding massive double-exponential disk galaxies with extended low surface brightness stellar disk: An IllustrisTNG exploration}, volume = {986}, year = {2025}, }
• (2025). A high-resolution, inversion-based synoptic study of solar granulation. ApJ, 986(2), 124. (www)

  @article{ , abstract = {The convectively driven, weakly magnetized regions of the solar photosphere dominate the Sun's surface at any given time, but the temporal variations of these quiet regions of the photosphere throughout the solar cycle are still not well known. To look for cycle-dependent changes in the convective properties of the quiet Sun photosphere, we use high spatial and spectral resolution spectropolarimetric observations obtained by the Hinode Solar Optical Telescope and apply the Spectropolarimetric Inversions Based on Response Functions code to infer physical conditions in the lower solar photosphere. Using a homogeneous set of 49 data sets, all taken at the disk center, we analyze the temperature stratification and the line-of-sight velocities of the granules and intergranules over a period of 15 years. We use a k-means clustering technique applied to the spectral profiles to segment the granules and intergranules based on both intensity and velocity. We also examine the profile bisectors of these different structures and compare them to past analyses. Our results show fairly constant properties over this period with no clear dependence on the solar cycle. We do, however, find a slight increase in the photospheric temperature gradient during the declining phase of the solar cycle. Our findings could have significant implications for understanding the coupling between the quiet Sun atmosphere and the global solar dynamo.}, archive = {J_ApJ}, author = {James W. Crowley and Ivan Milić and Gianna Cauzzi and Kevin Reardon}, doi = {10.3847/1538-4357/add0ad}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {124}, shortjournal = {The Astrophys. J.}, title = {A high-resolution, inversion-based synoptic study of solar granulation}, volume = {986}, year = {2025}, }
• (2025). Alien type ia supernovae from the milky way merger history and one possible candidate: Kepler’s supernova. ApJ, 986(2), 123. (www)

  @article{ , abstract = {The Milky Way is a dynamic and evolving system shaped by numerous merger events throughout its history. These mergers bring stars with kinematic and dynamic properties differing from the main stellar population. However, it remains uncertain whether any of the Galactic supernova remnants can be attributed to such a merger origin. In this work, we compare the progenitor of Kepler's supernova to its nearby stars, "alien" stars, and in situ Milky Way stellar populations. We uncover the abnormal kinematics and dynamics of Kepler's supernova and propose that its progenitor may have an extragalactic origin. We call the Type Ia supernovae (SNe Ia) produced by stars accreted into the Milky Way through merger events "alien SNe Ia" since they are cosmic immigrants. We estimate the rate of alien SNe Ia exploded recently using two methods: through galactic chemical evolution, and through a method without considering exact star formation history, introduced for the first time in this paper. We consider the past accretion of a few major satellite galaxies—Kraken, Gaia–Enceladus–Sausage, the Helmi streams, Sequoia, Sagittarius, Wukong/LMS-1, and Cetus—assuming these were dry mergers. The first method yields 1.5 × 10 −5 –5.0 × 10 −5 yr −1 , while the second method yields a comparable {3.1}_{-1.1}^{+1.8}\times 1{0}^{-5}\,{\mathrm{yr}}^{-1} as the rate estimates for recent alien SNe Ia. These estimates represent lower bounds because we assumed no postmerger star formation.}, archive = {J_ApJ}, author = {Wenlang He and Ping Zhou and Eda Gjergo and Xiaoting Fu}, doi = {10.3847/1538-4357/add32b}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {123}, shortjournal = {The Astrophys. J.}, title = {Alien type ia supernovae from the milky way merger history and one possible candidate: Kepler’s supernova}, volume = {986}, year = {2025}, }
• (2025). NO and c-C3H2 in the outer galaxy: High molecular abundances at RGC > 13 kpc. ApJ, 986(2), 122. (www)

  @article{ , abstract = {Observations of the J Ka, Kc = 4 1,4 → 3 0,3 , 4 0,4 → 3 1,3 , and 2 2,0 → 1 1,1 rotational lines of c-C 3 H 2 and the J = 3/2 → 1/2, Ω = 1/2 transition of NO (X 2 Π r ) were conducted at 2 mm toward 20 Galactic edge clouds with R GC = 10.8–23.5 kpc using the Arizona Radio Observatory 12 m telescope. The c-C 3 H 2 molecule was detected in all 20 objects in the sample, based typically on 2–3 transitions. NO, which exhibits a distinct pattern of lambda doubling and hyperfine splitting in the measured line, was identified in 16 clouds, with distances as far as R GC ∼ 23.5 kpc. While a 3 mm transition of c-C 3 H 2 had been observed before in some of the sample clouds, NO had not previously been detected at such large distances from the Galactic center. These new identifications double the number of molecular clouds known to contain NO. From a radiative transfer analysis, fractional abundances, relative to H 2 , were determined to be f (c-C 3 H 2 ) ∼ 0.5–39.8 × 10 −10 and f (NO) ∼ 0.2–21.2 × 10 −8 . These abundances are comparable to values observed in molecular clouds in the inner Galaxy (R GC < 12 kpc). The abundances therefore appear to remain relatively constant with increasing galactocentric distance. These results suggest that elemental abundance gradients at R GC ≥ 15 kpc in C, N, and O are not as severe as predicted. They also indicate that gas-phase chemistry in the outer Galaxy is quite robust, strengthening the case for widening the extent of the Galactic habitable zone.}, archive = {J_ApJ}, author = {L. A. Koelemay and L. M. Ziurys}, doi = {10.3847/1538-4357/add32d}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {122}, shortjournal = {The Astrophys. J.}, title = {NO and c-C3H2 in the outer galaxy: High molecular abundances at RGC > 13 kpc}, volume = {986}, year = {2025}, }
• (2025). Exoplanet ephemerides change observations (ExoEcho). II. transit timing variation analysis of brown dwarfs around solar-type stars. ApJ, 986(2), 121. (www)

  @article{ , abstract = {Transit timing variation (TTV) is a useful tool for studying the orbital properties of transiting objects. However, few TTV studies have been done on transiting brown dwarfs (BDs) around solar-type stars. Here we study the long-term TTV of a population of close BD companions around solar-type stars using Transiting Exoplanet Survey Satellite data. We use the measured orbital period change rate to constrain the tidal interaction strength between the host star and the BD companion and put limits on the destruction timescale of these transiting BDs. However, we find no statistically significant evidence of orbital decay or expansion in our sample based on the current data. This may be due to either poor observational data or inherently weak tidal dissipation. We then perform simulations to investigate future observation strategies for detecting orbital decay of transiting BDs, which show that NGTS-7A b, TOI-263​​​​​ b, and LP 261-75 b are the most promising targets in the next few years. Our study demonstrates the potential of TTV technique to probe the formation and evolution of close BD companions around solar-type stars.}, archive = {J_ApJ}, author = {Wenqin Wang and Xinyue Ma and Zhangliang Chen and Cong Yu and Shangfei Liu and Bo Ma}, doi = {10.3847/1538-4357/add3f2}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {121}, shortjournal = {The Astrophys. J.}, title = {Exoplanet ephemerides change observations (ExoEcho). II. transit timing variation analysis of brown dwarfs around solar-type stars}, volume = {986}, year = {2025}, }
• (2025). Testing the rossby paradigm: Weakened magnetic braking in early K-type stars. ApJ, 986(2), 120. (www)

  @article{ , abstract = {There is an intricate relationship between the organization of large-scale magnetic fields by a stellar dynamo and the rate of angular momentum loss due to magnetized stellar winds. An essential ingredient for the operation of a large-scale dynamo is the Coriolis force, which imprints organizing flows on the global convective patterns and inhibits the complete cancellation of bipolar magnetic regions. Consequently, it is natural to expect a rotational threshold for large-scale dynamo action and for the efficient angular momentum loss that it mediates through magnetic braking. Here we present new observational constraints on magnetic braking for an evolutionary sequence of six early K-type stars. To determine the wind braking torque for each of our targets, we combine spectropolarimetric constraints on the large-scale magnetic field, Ly α or X-ray constraints on the mass-loss rate, as well as uniform estimates of the stellar rotation period, mass, and radius. As identified previously from similar observations of hotter stars, we find that the wind braking torque decreases abruptly by more than an order of magnitude at a critical value of the stellar Rossby number. Given that all of the stars in our sample exhibit clear activity cycles, we suggest that weakened magnetic braking may coincide with the operation of a subcritical stellar dynamo.}, archive = {J_ApJ}, author = {Travis S. Metcalfe and Pascal Petit and Jennifer L. van Saders and Thomas R. Ayres and Derek Buzasi and Oleg Kochukhov and Keivan G. Stassun and Marc H. Pinsonneault and Ilya V. Ilyin and Klaus G. Strassmeier and Adam J. Finley and Rafael A. García and Daniel Huber and Yuxi (Lucy) Lu and Victor See}, doi = {10.3847/1538-4357/add40a}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {120}, shortjournal = {The Astrophys. J.}, title = {Testing the rossby paradigm: Weakened magnetic braking in early K-type stars}, volume = {986}, year = {2025}, }
• (2025). Evidence of interaction between ion-scale waves and ion velocity distributions in the solar wind. ApJ, 986(2), 119. (www)

  @article{ , abstract = {Recent in situ observations from Parker Solar Probe (PSP) near perihelia reveal ion beams, temperature anisotropies, and kinetic wave activity. These features are likely linked to solar wind heating and acceleration. During PSP Encounter 17 (at 11.4 R s ) on 2023 September 26, the PSP/FIELDS instrument detected enhanced ion-scale wave activity associated with deviations from local thermodynamic equilibrium in ion velocity distribution functions (VDFs) observed by the PSP/Solar Probe Analyzers-Ion. Dense beams (secondary populations) were present in the proton VDFs during this wave activity. Using bi-Maxwellian fits to the proton VDFs, we found that the density of the proton beam population increased during the wave activity and, unexpectedly, surpassed the core population at certain intervals. Interestingly, the wave power was reduced during the intervals when the beam population density exceeded the core density. The drift velocity of the beams decreases from 0.9 to 0.7 of the Alfvén speed, and the proton core shows a higher temperature anisotropy ( T ⊥ / T ∥ > 2.5) during these intervals. We conclude that the observations during these intervals are consistent with a reconnection event during a heliospheric current sheet crossing. During this event, α -particle parameters (density, velocity, and temperature anisotropy) remained nearly constant. Using linear analysis, we examined how the proton beam drives instability or wave dissipation. Furthermore, we investigated the nonlinear evolution of ion kinetic instabilities using hybrid kinetic simulations. This study provides direct clues about energy transfer between particles and waves in the young solar wind.}, archive = {J_ApJ}, author = {Yogesh and Leon Ofman and Scott A. Boardsen and Kristopher Klein and Mihailo Martinović and Viacheslav M. Sadykov and Jaye L. Verniero and Niranjana Shankarappa and Lan K. Jian and Parisa Mostafavi and Jia Huang and K. W. Paulson}, doi = {10.3847/1538-4357/add467}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {119}, shortjournal = {The Astrophys. J.}, title = {Evidence of interaction between ion-scale waves and ion velocity distributions in the solar wind}, volume = {986}, year = {2025}, }
• (2025). A generalized method to measure the lorentz factor from gamma-ray burst photospheric emission. ApJ, 986(2), 118. (www)

  @article{ , abstract = {The properties of gamma-ray bursts (GRBs) that are inferred from observations depend on the value of the bulk Lorentz factor, Γ. Consequently, accurately estimating it is an important aim. In this work, we present a method of measuring Γ based on observed photospheric emission, which can also be used for highly dissipative flows that may lead to nonthermal spectral shapes. For the method to be applicable, two conditions need to be met: the photon number should be conserved in the later stages of the jet, and the original photon temperature must be inferred from the data. The case of dissipation via subphotospheric shocks is discussed in detail, and we show that the method is particularly efficient when a low-energy spectral break is identified. We demonstrate the capabilities of the method by applying it to two different GRB spectra. From one of the spectra, we obtain a value for Γ with statistical uncertainties of only ∼15%, while for the other spectrum we only obtain an upper limit.}, archive = {J_ApJ}, author = {Oscar Wistemar and Felix Ryde and Filip Alamaa}, doi = {10.3847/1538-4357/add52d}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {118}, shortjournal = {The Astrophys. J.}, title = {A generalized method to measure the lorentz factor from gamma-ray burst photospheric emission}, volume = {986}, year = {2025}, }
• (2025). A third star in the HAT-P-7 system and a new dynamical pathway to misaligned hot jupiters. ApJ, 986(2), 117. (www)

  @article{ , abstract = {The retrograde orbit of the hot Jupiter HAT-P-7b is suggestive of high-eccentricity (high-e) migration caused by dynamical interactions with a massive companion. However, the only other known body in the system is an M dwarf located ∼10 3 au away, too distant to cause high-e migration without fine-tuning. Here, we present transit-timing and radial-velocity evidence for an additional stellar companion with a semimajor axis of 3{2}_{-11}^{+16} au, eccentricity 0.7{6}_{-0.26}^{+0.12} , and minimum mass of 0.1{9}_{-0.06}^{+0.11} M ⊙ . We investigate several dynamical routes by which this nearby companion star could have played a role in converting a cold Jupiter into the retrograde hot Jupiter that is observed today. Of particular interest is a novel "eccentricity cascade" mechanism involving both of the companion stars: the outer companion periodically excites the eccentricity of the inner companion through von Zeipel–Lidov–Kozai cycles, and this eccentricity excitation is slowly transferred to the cold Jupiter via successive close encounters, eventually triggering its high-e migration. The plausibility of this mechanism in explaining HAT-P-7b shows that stellar companions traditionally considered too distant to cause hot Jupiter formation might nevertheless be responsible, with the aid of closer-orbiting massive companions. With these developments, HAT-P-7b is one of the few hot Jupiters for which a complete high-e migration history can be simulated based only on observed bodies, rather than invoking bodies that are beneath detection limits or that are no longer in the system.}, archive = {J_ApJ}, author = {Eritas Yang and Yubo Su and Joshua N. Winn}, doi = {10.3847/1538-4357/add5f7}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {117}, shortjournal = {The Astrophys. J.}, title = {A third star in the HAT-P-7 system and a new dynamical pathway to misaligned hot jupiters}, volume = {986}, year = {2025}, }
• (2025). Bottom-up background simulations of the 2016 COSI balloon flight. ApJ, 986(2), 116. (www)

  @article{ , abstract = {The Compton Spectrometer and Imager (COSI) is a Compton telescope designed to survey the 0.2–5 MeV sky, consisting of a compact array of cross-strip germanium detectors. As part of its development, in 2016 COSI had a successful 46 day flight on board NASA's Super Pressure Balloon platform. This was a precursor to the COSI Small Explorer (COSI-SMEX) satellite mission that will launch in 2027 into an equatorial low Earth (530 km) orbit. The observation of MeV gamma rays is dominated by background radiation, especially due to the activation of the detector materials induced by cosmic-ray interactions. Thus, background simulation and identification are crucial for the data analysis. Because the COSI-SMEX detectors will be similar to the ones used for the balloon flight, the balloon measurements provide an important tool for testing and cross-checking our background simulations for the upcoming space mission. In this work we perform Monte Carlo simulations of the background emission from the 2016 COSI balloon flight. Including a phenomenological shape correction, we obtain an agreement with the data at the 10%–20% level for energies between 0.1 and 1.6 MeV, and we successfully reproduce most of the activation lines induced by cosmic-ray interactions.}, archive = {J_ApJ}, author = {Savitri Gallego and Uwe Oberlack and Jan Lommler and Christopher M. Karwin and Andreas Zoglauer and Pierre Jean and Peter von Ballmoos and Carolyn Kierans and Clio Sleator and John A. Tomsick and Steven E. Boggs and (On Behalf of the COSI Collaboration)}, doi = {10.3847/1538-4357/add6a0}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {116}, shortjournal = {The Astrophys. J.}, title = {Bottom-up background simulations of the 2016 COSI balloon flight}, volume = {986}, year = {2025}, }
• (2025). A statistical analysis of the returning flux tubes in the jovian magnetosphere based on juno observations. ApJ, 986(2), 115. (www)

  @article{ , abstract = {The interchange process is an important mechanism for radial transport of plasma in the magnetospheres of the gas giants, namely Jupiter and Saturn. During this process, dense and cold flux tubes that move outwards are replaced by returning flux tubes with warm and tenuous plasma. In this study, we conduct a statistical analysis of the magnetic variation and plasma properties inside the returning flux tubes, based on the observations from magnetometer (MAG) and JADE onboard the Juno spacecraft during its first 45 perijove traverses. We detect the returning flux tubes by recognizing the low-energy electron flux sudden drop, within the range of M < 20 R J (Jupiter radii). The results have illustrated that the flux tubes with increased magnetic field account for the majority of the events. There is no significant relationship between the events with increased or decreased magnetic field and magnetic latitude, and both types of events are observed mostly near the equatorial plane, while events with depressed magnetic field are more frequently observed at larger distances from Jupiter with longer time duration (or larger flux tube volume). Furthermore, the crossover energy separating decreased low-energy electron flux and increased high-energy electron flux of the returning flux tubes is around several keV, depending on the type of magnetic field variation. These results provide great insight into the mass and magnetic flux transport in the inner Jovian magnetosphere.}, archive = {J_ApJ}, author = {Dong-Wen He and Chao Yue and Hao-Bo Fu and Fan Yang and Michel Blanc and Xu-Zhi Zhou and Qiu-Gang Zong}, doi = {10.3847/1538-4357/add722}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {115}, shortjournal = {The Astrophys. J.}, title = {A statistical analysis of the returning flux tubes in the jovian magnetosphere based on juno observations}, volume = {986}, year = {2025}, }
• (2025). Mutual validation of data sets for analyzing tilt angles in solar active regions. ApJ, 986(2), 114. (www)

  @article{ , abstract = {The tilt angle of solar active regions (ARs) is crucial for the Babcock–Leighton-type dynamo models in the buildup of the polar field. However, divergent results regarding properties of tilt angles were reported due to their wide scatter, caused by intrinsic solar mechanisms and measurement errors. Here, we mutually validate the magnetogram-based AR tilt angle data set from Wang, Jiang, and Luo with the Debrecen Photoheliographic Data by identifying common data points where both data sets provide comparable tilt angles for the same AR/sunspot. The mutually validated data sets effectively reduce measurement errors, enabling a more accurate analysis of the intrinsic properties of tilt angles. Our mutually validated data sets reveal that the difference between white-light-based and magnetogram-based tilt angles is not significant. Also, the data sets show that an upward revision of average tilt angle ( \bar{\alpha } ) and a downward revision of the tilt scatter ( σ α ) compared to previous results are necessary, with typical values of about 7° and 16°, respectively. The σ α values demonstrate a strong correlation with AR flux and sunspot area, with the dependency functions reevaluated using mutually validated data sets. Furthermore, both \bar{\alpha } and the tilt coefficient for the weak cycle 24 are larger than those for cycle 23. This supports the tilt quenching mechanism, which posits an anticorrelation between the cycle-averaged tilt angle and cycle amplitude. Additionally, tilt angle from the mutually validated data set has a weak nonmonotonic relationship with magnetic flux and does not depend on the maximum magnetic field strength of ARs.}, archive = {J_ApJ}, author = {Lang Qin and Jie Jiang and Ruihui Wang}, doi = {10.3847/1538-4357/add93a}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {114}, shortjournal = {The Astrophys. J.}, title = {Mutual validation of data sets for analyzing tilt angles in solar active regions}, volume = {986}, year = {2025}, }
• (2025). Correlations between the crustal field and the magnetization layer’s geometry in the martian magnetic lineation area. ApJ, 986(2), 113. (www)

  @article{ , abstract = {Magnetic lineations on Mars, the remanent magnetization presents east–west-trending banded features, were suggested to be associated with seafloor spreading, dike intrusion, hot spot tracking, mantle convection, discrete source merging, etc. However, a missing link remains between the magnetization layer's geometry, controlled by these processes, and the scale and magnitude of magnetic signals in the satellite orbit. Combining the magnetic field anomalies with the geometry of the crust, we find high correlations between the polarity of the radial field and the crustal thickness in the Martian southern highlands. Forward modeling is also used to reproduce the magnetic lineations based on the magnetization layer with a nonuniform thickness in a 25 km crust. The forward modeling results show lateral variation in the radial field ranges 10∼40 nT per degree, comparable to the result from the spherical harmonic model based on satellite data. Our study suggests the mantle plume upwelling causes the nonuniformity in the magnetization layer, producing strip-shaped magnetic anomalies with periodic polarity reversals.}, archive = {J_ApJ}, author = {Jipeng Qin and Can Huang and Hao Luo and Yasong Ge and Lin Tian and Kuixiang Zhang and Lei Wang and Ying Zhang and Lican Shan and Aimin Du}, doi = {10.3847/1538-4357/add9a3}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {113}, shortjournal = {The Astrophys. J.}, title = {Correlations between the crustal field and the magnetization layer’s geometry in the martian magnetic lineation area}, volume = {986}, year = {2025}, }
• (2025). The ultradiffuse galaxy AGC 242019 with a negative metallicity gradient. ApJ, 986(2), 112. (www)

  @article{ , abstract = {The origin of ultradiffuse galaxies (UDGs) remains poorly understood. While the metallicity gradient can offer key clues about the formation mechanisms of UDGs, no such studies have been conducted for field UDGs. We carry out deep MUSE observations of one of the brightest UDGs in the H i —AGC 242019. With various strong emission-line metallicity calibrators, we found that this galaxy shows a negative metallicity gradient: -0.08\pm 0.02\,{\mathrm{kpc}}^{-1}/-0.30\pm 0.07\,{R}_{{\rm{e}}}^{-1} for N2S2H α metallicity calibrator and -0.028\pm 0.006\,{\mathrm{kpc}}^{-1}/-0.11\,\pm 0.02\,{R}_{{\rm{e}}}^{-1} for O3N2, with average metallicities of 7.6  ±  0.2 and 8.4  ±  0.1, respectively. By comparing with local dwarfs and spirals, we find that AGC 242019 shows a similar metallicity gradient to local dwarfs. This result suggests that AGC 242019 may not be the result of a dwarf that experiences very strong feedback.}, archive = {J_ApJ}, author = {Junbao Ni and Yong Shi and Xin Li and Zhiyuan Zheng and Zhiyu Zhang and Xiaoling Yu and Fuyan Bian and Jianhang Chen and Junzhi Wang}, doi = {10.3847/1538-4357/addbdb}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {112}, shortjournal = {The Astrophys. J.}, title = {The ultradiffuse galaxy AGC 242019 with a negative metallicity gradient}, volume = {986}, year = {2025}, }
• (2025). A measurement of the largest-scale CMB E-mode polarization with CLASS. ApJ, 986(2), 111. (www)

  @article{ , abstract = {We present measurements of large-scale cosmic microwave background E -mode polarization from the Cosmology Large Angular Scale Surveyor 90 GHz data. Using 115 det-yr of observations collected through 2024 with a variable-delay polarization modulator, we achieved a polarization sensitivity of 82\,\mu {\rm{K}}\,{\rm{arcmin}} , comparable to Planck at similar frequencies (100 and 143 GHz ). The analysis demonstrates effective mitigation of systematic errors and addresses challenges to large-angular-scale power recovery posed by time-domain filtering in maximum-likelihood map-making. A novel implementation of the pixel-space transfer matrix is introduced, which enables efficient filtering simulations and bias correction in the power spectrum using the quadratic cross-spectrum estimator. Overall, we achieved an unbiased time-domain filtering correction to recover the largest angular scale polarization, with the only power deficit, arising from map-making nonlinearity, being characterized as <3%. Through cross-correlation with Planck, we detected the cosmic reionization at 99.4% significance and measured the reionization optical depth \tau =0.05{3}_{-0.019}^{+0.018} , marking the first ground-based attempt at such a measurement. At intermediate angular scales ( ℓ > 30), our results, both independently and in cross-correlation with Planck, remain fully consistent with Planck's measurements.}, archive = {J_ApJ}, author = {Yunyang Li and Joseph R. Eimer and John W. Appel and Charles L. Bennett and Michael K. Brewer and Sarah Marie Bruno and Ricardo Bustos and Carol Yan Yan Chan and David T. Chuss and Joseph Cleary and Sumit Dahal and Rahul Datta and Jullianna Denes Couto and Kevin L. Denis and Rolando Dünner and Thomas Essinger-Hileman and Kathleen Harrington and Kyle Helson and Johannes Hubmayr and Jeffrey Iuliano and John Karakla and Tobias A. Marriage and Nathan J. Miller and Carolina Morales Perez and Lucas P. Parker and Matthew A. Petroff and Rodrigo A. Reeves and Karwan Rostem and Caleigh Ryan and Rui Shi and Koji Shukawa and Deniz A. N. Valle and Duncan J. Watts and Janet L. Weiland and Edward J. Wollack and Zhilei Xu and Lingzhen Zeng}, doi = {10.3847/1538-4357/adc723}, journal = {The Astrophysical Journal}, month = {6}, number = {2}, pages = {111}, shortjournal = {The Astrophys. J.}, title = {A measurement of the largest-scale CMB E-mode polarization with CLASS}, volume = {986}, year = {2025}, }
• (2025). Leptohadronic multimessenger modeling of two high-redshift (z > 1) neutrino emission blazar candidates. ApJ, 986(1), 110. (www)

  @article{ , abstract = {The blazars are one of the leading candidate sources of high-energy neutrinos. Recently, two blazars have been found to be temporally and spatially correlated with some IceCube high-energy neutrino events. The two blazars, GB6 J2113+1121 and NVSS J171822+423948, are flat spectrum radio quasars (FSRQs) with redshifts greater than unity. In particular, NVSS J171822+423948 has a redshift of 2.7, which provides an important probe for studying the radiation processes of jets from active galactic nuclei in the early Universe. To better understand the physical origin of the IceCube neutrinos, we adopt the one-zone leptohadronic model to fit the multimessenger emission of GB6 J2113+1121 and NVSS J171822+423948 during their γ -ray flaring periods and then calculate the high-energy neutrino detection probability. The chance of detecting a single muon neutrino from these two sources is found to be ∼2% and 0.8%, respectively. Although such detection rates are not high mainly because of their high redshifts, our investigation strongly suggests that these sources are efficient PeV neutrino emitters. Our results also indicate that electromagnetic cascades produced by hadronic processes contribute significantly to X-ray and γ -ray emissions. However, high-energy γ -rays can be severely absorbed by the soft photon field from the broad-line region, which weakens the correlation between γ -rays and neutrinos, while suggesting a stronger connection between X-rays and neutrinos. We predict that IceCube will continue to detect neutrinos from FSRQs with redshifts greater than 1 in the future.}, archive = {J_ApJ}, author = {Xiong Jiang and Neng-Hui Liao and Rui Xue and Yi-Zhong Fan and Da-Ming Wei}, doi = {10.3847/1538-4357/add1b5}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {110}, shortjournal = {The Astrophys. J.}, title = {Leptohadronic multimessenger modeling of two high-redshift (z > 1) neutrino emission blazar candidates}, volume = {986}, year = {2025}, }
• (2025). Impact of thermonuclear reaction rate uncertainties on the identification of presolar grains from classical novae. ApJ, 986(1), 109. (www)

  @article{ , abstract = {Approximately 30%–40% of classical novae generate dust between 20 and 100 days following the eruption. However, there has yet to be a definitive identification of presolar stardust grains originating from classical novae. While multiple studies have suggested a nova origin for specific grains, aligning simultaneously all measured isotopic ratios of a specific grain with those predicted from simulations remains challenging. Using Monte Carlo simulations, this work investigates how uncertainties in thermonuclear reaction rates influence the isotopic ratios predicted in simulations of classical novae, specifically impacting the identification of presolar grains. In particular, we address two questions: (i) What is the impact of uncertainties in reaction rates on the range of isotopic ratios predicted by classical nova simulations? (ii) Which reaction rate uncertainties most significantly influence the predicted abundance ratios in presolar grains? Our results show that current reaction rate uncertainties affect the isotopic ratios of 12 C/ 13 C, 14 N/ 15 N, 16 O/ 17 O, 16 O/ 18 O, 24 Mg/ 25 Mg, 24 Mg/ 26 Mg, 26 Al/ 27 Al, and 28 Si/ 29 Si by less than 20% in either carbon–oxygen or oxygen–neon (ONe) novae, especially when considering the mixing of matter throughout the entire envelope. However, the isotopic ratios of 28 Si/ 30 Si, 32 S/ 33 S, and 32 S/ 34 S in ONe novae are exceptions: their variability greatly exceeds a factor of 2 due to the uncertainties in the reaction rates of 30 P(p, γ ) 31 S, 33 S(p, γ ) 34 Cl, and 34 S(p, γ ) 35 Cl, respectively. These results highlight the significant influence of specific reaction rates on the predicted abundance ratios and underscore the necessity for accurate nuclear measurements to reduce these uncertainties.}, archive = {J_ApJ}, author = {Lauren Ward and Christian Iliadis and Maitrayee Bose and Caleb Marshall and Athanasios Psaltis and Sumner Starrfield}, doi = {10.3847/1538-4357/add47a}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {109}, shortjournal = {The Astrophys. J.}, title = {Impact of thermonuclear reaction rate uncertainties on the identification of presolar grains from classical novae}, volume = {986}, year = {2025}, }
• (2025). An unusual change in the radio jets of GRS 1915+105. ApJ, 986(1), 108. (www)

  @article{ , abstract = {We compare Very Large Array observations of GRS 1915+105 made in 1994 and 2023, with nearly three decades of difference. The source has experienced intriguing major changes. The position angle of the bipolar ejecta in the plane of the sky has increased counterclockwise by 24°. The inclination angle of the flow with respect to the line of sight has increased by 17°. The observations of 2023 also show the temporal quasi-sinusoidal radio oscillations reported for several previous epochs. However, the 2023 oscillations are faster than ever before, with a period of about 8 minutes as opposed to the periods in the range of 20–40 minutes observed in previous epochs. Analysis of GRS 1915+105 images over the years suggests that the observed changes took place within a year or less. Our analysis indicates that during 2023, the plane of the accretion disk with an accretion rate enhanced by a factor of ∼4.3 was aligned with the line of sight, which may explain the deep X-ray obscured state and the high mid-infrared luminosity observed with JWST in that epoch. More recent 2024 observations show that the position angle of the ejecta has returned to its historic values. Future monitoring of the time evolution of the source may clarify the cause of these remarkable changes.}, archive = {J_ApJ}, author = {Luis F. Rodríguez and I. Félix Mirabel}, doi = {10.3847/1538-4357/adda33}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {108}, shortjournal = {The Astrophys. J.}, title = {An unusual change in the radio jets of GRS 1915+105}, volume = {986}, year = {2025}, }
• (2025). Inclusion of Isomers/Astromers in s-process nucleosynthesis: The pivotal case of 85Kr. ApJ, 986(1), 107. (www)

  @article{ , abstract = {85 Kr is an s -process branch point nucleus: the competition between neutron capture and β decay influences the production of nearby nuclides. Its evolution is complicated by the existence of a long-lived isomer that β -decays on a much shorter timescale than the ground state. We calculate the effective thermal transition rates between the ground and isomeric states along with estimates of their thermal β -decay rates in a suite of nucleosynthesis computations to assess the consequences of this isomer on isotopic abundances. A central finding in this study is that the s -process flow with the isomer included under astrophysical conditions relevant for the s -process creates a shift in abundance yield of the important radioactivity 87 Rb by a factor of ∼2.4 relative to the case when the 85 Kr is taken to be internally equilibrated when neutron exposures approach the main branch limit. On the other hand, the 88 Sr/ 86 Sr ratio is little affected because the bulk of the flow through 85 Kr is still via beta decay, whether the isomer is taken into account or not.}, archive = {J_ApJ}, author = {Jaad A. Tannous and G. Wendell Misch and Matthew R. Mumpower and Bradley S. Meyer and F. X. Timmes and Aaron Couture and Chris L. Fryer}, doi = {10.3847/1538-4357/adda3c}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {107}, shortjournal = {The Astrophys. J.}, title = {Inclusion of Isomers/Astromers in s-process nucleosynthesis: The pivotal case of 85Kr}, volume = {986}, year = {2025}, }
• (2025). The soft X-ray aspect of gamma-ray bursts in the einstein probe era. ApJ, 986(1), 106. (www)

  @article{ , abstract = {The Einstein Probe (EP) satellite, dedicated to time-domain high-energy astrophysics and multimessenger astronomy, was recently launched and successfully put into operation. The Wide-field X-ray Telescope (WXT; 0.5–4 keV) on board has identified multiple gamma-ray burst (GRB) events, with an average duration of several hundred seconds. This duration is several times longer than the average duration of long gamma-ray bursts (LGRBs) detected by the Neil Gehrels Swift Observatory, which typically stands at several tens of seconds. Additionally, EP has detected some unknown X-ray transients whose connection to GRBs is uncertain, due to the absence of gamma-ray counterparts and efficient follow-up observation at multiple wavelengths. Several main factors could account for the longer time, including the Doppler effect of off-axis viewing, the spectral lag effect of the synchrotron spectrum of cooling electrons, and some unknown prolonged intrinsic X-ray activities. Our studies indicate that EP GRBs may primarily consist of off-axis-viewed bursts, forming a unique population among the GRB zoo, yet the intrinsic origin for the specific bursts could not be excluded. By analyzing the statistical properties of the historical LGRB samples, we explored observable properties of on-axis and off-axis LGRBs in the soft X-ray band. The predicted characteristics of off-axis-viewed GRBs, including the duration, the energy fluence, the low-energy spectral index, and the slopes of the Amati and Yonetoku relations, could be tested with a larger sample of GRB events detected by EP in the future.}, archive = {J_ApJ}, author = {Hao-Xuan Gao and Jin-Jun Geng and Yi-Fang Liang and Hui Sun and Fan Xu and Xue-Feng Wu and Yong-Feng Huang and Zi-Gao Dai and Wei-Min Yuan}, doi = {10.3847/1538-4357/adceb1}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {106}, shortjournal = {The Astrophys. J.}, title = {The soft X-ray aspect of gamma-ray bursts in the einstein probe era}, volume = {986}, year = {2025}, }
• (2025). The frequency-dependent modulation features of PSR j1948+3540. ApJ, 986(1), 105. (www)

  @article{ , abstract = {Using observations from the Giant Metrewave Radio Telescope and FAST, we conducted multiwavelength studies on PSR J1948+3540 and analyzed its intensity modulation characteristics in detail. We found that the intensity modulation of this pulsar exhibits broad low-frequency modulation features. The modulation frequency/period is time dependent, but the dominant modulation component varies with the observing frequency. Specifically, at low frequencies, the modulation is dominated by the first half of the middle component, while at high frequencies, it is dominated by the second half of the middle component. Spectral analysis revealed that the intensities of the leading and trailing components vary with the observing frequency, but the middle component does not change significantly. In addition, the polarization analyses reveal that the peak of the radiation intensity is located in the latter half of the middle component, whereas the linear polarization is dominant in the former half. However, due to the low degree of linear polarization, the change of the dominant modulation component with the observed frequency is not caused by the variation in linear polarization. The phenomenon of the dominant modulation component varying with observing frequency has not been reported before and remains difficult to understand within the current theoretical framework.}, archive = {J_ApJ}, author = {Kaige Chang and Na Wang and Feifei Kou and Wenming Yan and Jianping Yuan and Shijun Dang and Jumei Yao and Vishal Gajjar and Xia Zhou}, doi = {10.3847/1538-4357/add1b6}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {105}, shortjournal = {The Astrophys. J.}, title = {The frequency-dependent modulation features of PSR j1948+3540}, volume = {986}, year = {2025}, }
• (2025). Can the neutrinos from TXS 0506+056 have a coronal origin?. ApJ, 986(1), 104. (www)

  @article{ , abstract = {The blazar TXS 0506+056 has been the first astrophysical source associated with high-energy astrophysical neutrinos, and it has emerged as the second-most-prominent hotspot in the neutrino sky over 10 yr of observations. Although neutrino production in blazars has traditionally been attributed to processes in the powerful relativistic jet, the observation of a significant neutrino flux from NGC 1068—presumably coming from the active galactic nucleus (AGN) corona—suggests that neutrinos can also be produced in the cores of AGN. This raises the question whether neutrino production in TXS 0506+056 is also associated with the core region. We study this scenario, focusing on the hypothesis that this blazar is a masquerading BL Lac object, a high-excitation quasar with hidden broad emission lines and a standard accretion disk. We show that magnetic reconnection is an acceleration process necessary to reach tens of PeV proton energies, and we use observationally motivated estimates of the X-ray luminosity of the coronal region to predict the emission of secondaries and compare them to the observed multiwavelength and neutrino spectra of the source. We find that the coronal neutrino emission from TXS 0506+056 is too low to describe the IceCube observed neutrinos from this AGN, which in turn suggests that the blazar jet remains the preferred location for neutrino production.}, archive = {J_ApJ}, author = {Damiano F. G. Fiorillo and Federico Testagrossa and Maria Petropoulou and Walter Winter}, doi = {10.3847/1538-4357/add267}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {104}, shortjournal = {The Astrophys. J.}, title = {Can the neutrinos from TXS 0506+056 have a coronal origin?}, volume = {986}, year = {2025}, }
• (2025). The formation of double hot jupiter systems through von Zeipel–Lidov–Kozai migration. ApJ, 986(1), 103. (www)

  @article{ , abstract = {The von Zeipel–Lidov–Kozai (ZLK) mechanism with tidal friction has been demonstrated as a promising avenue to generate hot Jupiters in stellar binary systems. Previous population studies of hot Jupiter formation have largely examined this mechanism in systems comprised of three bodies: two stars and one planet. However, because stars in a binary system form in similar environments with comparable metallicities, the formation of a single hot Jupiter in such a system may imply that the conditions are more likely met for the companion star as well. We investigate the ZLK mechanism with tidal friction as a potential mechanism to produce double hot Jupiter systems in stellar binaries. Using N -body simulations, we characterize the evolution of two cold Jupiters, each orbiting one star in a binary system, undergoing mirrored ZLK migration. We then examine the robustness of this mechanism to asymmetries in stellar masses, planet masses, and planet orbital inclinations relative to the binary plane. We predict that, under the assumptions that (1) most hot Jupiters in binary star systems form through ZLK migration of primordially formed cold Jupiters and (2) if one star in the binary system forms a cold Jupiter, the second does as well. A comprehensive search could identify double hot Jupiters in up to ∼9% of the close- to moderate-separation ( a * ≤ 2000 au) binary systems that already host a known hot Jupiter. We also argue that a blind search for ZLK-migrated double hot Jupiters should prioritize twin stellar binaries with pericenter approaches of a few hundred astronomical units.}, archive = {J_ApJ}, author = {Yurou Liu and Tiger Lu and Malena Rice}, doi = {10.3847/1538-4357/add405}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {103}, shortjournal = {The Astrophys. J.}, title = {The formation of double hot jupiter systems through von Zeipel–Lidov–Kozai migration}, volume = {986}, year = {2025}, }
• (2025). Rapid spatiotemporal evolution of vertical electric currents during an X-class flare. ApJ, 986(1), 102. (www)

  @article{ , abstract = {In this paper, we present a detailed analysis of the spatiotemporal evolution of photospheric vertical electric currents (VECs) during an X1.1 flare (SOL2013-11-10T05:08). The VEC on the solar surface is calculated using the 135 s high-temporal-resolution vector magnetograms obtained from the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory. In the region, a highly sheared magnetic channel that is also a polarity inversion line (PIL) divides the region into two parts. The spatial configuration of VEC ribbons is always conjugate footprints, and it takes the form of a sigmoid along two sides of the PIL at the beginning of the flare. The temporal evolution of the VECs shows a rapid enhancement associated with the impulsive phase of the flare, and mean horizontal fields in this region show similar temporal behavior. The most prominent enhancement of VECs not only shows up along the two sides of the enhancement B h but also spreads outward along the PILs. The VECs in positive and negative fields have an initial separation motion and are followed by an apparent approaching motion. In contrast, the flaring loops and white-light flare ribbons have an initial contraction and later expansion motion. Our results show that the rapid change of magnetic fields related to flares has a predominant role in affecting the spatiotemporal evolution of VECs.}, archive = {J_ApJ}, author = {Jinhua Shen and Xu Yang and Jianping Li and Yangyu Liu and Yingna Su and Haisheng Ji}, doi = {10.3847/1538-4357/add92d}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {102}, shortjournal = {The Astrophys. J.}, title = {Rapid spatiotemporal evolution of vertical electric currents during an X-class flare}, volume = {986}, year = {2025}, }
• (2025). Active galactic nuclei and host galaxies in COSMOS-web. II. first look at the kiloparsec-scale dual and offset AGN population. ApJ, 986(1), 101. (www)

  @article{ , abstract = {Kiloparsec-scale dual and offset active galactic nuclei (AGNs) are signposts of accreting supermassive black holes (SMBHs) triggered during late-stage galaxy mergers, offering crucial insights into the coevolution of SMBHs and galaxies. However, robustly confirmed systems at high redshift (e.g., z > 1) are scarce and biased toward the most luminous and unobscured systems. In this study, we systematically search for kiloparsec-scale (projected separation  <15 kpc) dual and offset AGNs around 571 moderate-luminosity, X-ray-selected AGNs, including the obscured population, utilizing deep Hubble Space Telescope Advanced Camera for Surveys/F814W and multiband JWST NIRCam imaging from the COSMOS-Web survey. We identify 59 dual and 30 offset AGN candidates in late-stage major mergers based on spatially resolved spectral energy distribution analyses. This translates to  ∼28 and  ∼10 bona fide dual and offset AGNs, using a probabilistic pair-counting scheme to minimize chance superpositions. Notably, the fraction of dual and offset AGNs among moderate-luminosity ( L bol ∼ 10 43 −10 46 erg s −1 ) obscured AGNs is nearly 2 orders of magnitude higher than that of the most luminous, unobscured quasar pairs. We find tentative evidence for an increasing pair fraction among AGNs with redshift (from a few percent at z ∼ 0.5 to \sim 22.{9}_{-17.7}^{+27.5} \% at z ∼ 4.5) and a higher occurrence rate of dual over offset AGNs. There is no pileup of dual/offset AGNs below  ∼2kpc separations. These results generally align with predictions from the ASTRID and Horizon-AGN cosmological simulations, when matching sample selection criteria, implying a high probability of both black holes being active simultaneously in late-stage major mergers.}, archive = {J_ApJ}, author = {Junyao Li and Ming-Yang Zhuang and Yue Shen and Marta Volonteri and Nianyi Chen and Tiziana Di Matteo}, doi = {10.3847/1538-4357/adbae2}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {101}, shortjournal = {The Astrophys. J.}, title = {Active galactic nuclei and host galaxies in COSMOS-web. II. first look at the kiloparsec-scale dual and offset AGN population}, volume = {986}, year = {2025}, }
• (2025). The cosmic evolution of fast radio bursts inferred from the CHIME/FRB baseband catalog 1. ApJ, 986(1), 100. (www)

  @article{ , abstract = {Redshift and luminosity distributions are essential for understanding the cosmic evolution of extragalactic objects and phenomena, such as galaxies, gamma-ray bursts, and fast radio bursts (FRBs). For FRBs, these distributions are primarily estimated using the fluence and the dispersion measure (DM). Calibrating their joint distribution has been challenging due to a lack of accurate fluences in the intensity data of the CHIME/FRB survey. Using the baseband update of CHIME/FRB Catalog 1, we calibrate the 2D fluence–DM distribution for the first time. We find the energy distribution is described well by a Schechter function with a power-law slope of -1.9{4}_{-0.12}^{+0.14} . Testing two types of redshift evolution models suggests a likely combination of young and old formation channels. 3{1}_{-21}^{+31} % of FRB sources may track star formation, or correspondingly, FRB sources may have delay times of 1.9{4}_{-1.31}^{+1.54} Gyr. A pure star formation tracking population is excluded by only one model at >2 σ confidence. An updated cosmic star formation rate density evolution up to redshift 14 is constrained by compiling results from several JWST studies. The furthest FRB detection with planned radio facilities is expected to be at z ≈ 5. A radio telescope operating at 200 MHz with a system-equivalent flux density of ≤0.07 Jy (equivalent to a detection threshold of 1 mJy ms) and instantaneous sky coverage of ≳400 deg 2 should be able to detect 63{0}_{-485}^{+730} FRBs yr −1 at z ≳ 6 and 5{3}_{-43}^{+83} FRBs yr −1 at z ≳ 8, which is sufficient to differentiate between reionization histories.}, archive = {J_ApJ}, author = {Om Gupta and Paz Beniamini and Pawan Kumar and Steven L. Finkelstein}, doi = {10.3847/1538-4357/add14c}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {100}, shortjournal = {The Astrophys. J.}, title = {The cosmic evolution of fast radio bursts inferred from the CHIME/FRB baseband catalog 1}, volume = {986}, year = {2025}, }
• (2025). Fermi-LAT discovery of a gamma-ray outburst from the peculiar compact steep spectrum radiogalaxy 3C 216. ApJ, 986(1), 99. (www)

  @article{ , abstract = {3C 216 is an extragalactic radio source classified as a compact steep spectrum (CSS) object, associated with the source 4FGL J0910.0+4257 detected by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope. The source exhibits extended radio structures as well as an inner relativistic jet. In general, jets accelerated by active galactic nuclei (AGNs) are efficient sources of nonthermal radiation, spanning from the radio band to X-ray and gamma-ray energies. Due to relativistic beaming, much of this radiation, particularly in the high-energy domain, is concentrated within a narrow cone aligned with the jet's direction. Consequently, high-energy emission is more easily detected in blazars , where the jet is closely aligned with the line of sight of the observer. Beginning in 2022 November, Fermi-LAT observed increased gamma-ray activity from 3C 216, culminating in a strong outburst in 2023 May. This event was followed up by observations from the Neil Gehrels Swift Observatory telescope. In this work, we perform a careful analysis of the multifrequency data (gamma ray, X-ray, UV, optical) collected during this observational campaign. We find that the spectral energy distribution (SED) of the flaring source evolves in a coherent way, supporting a common origin for the multifrequency emission. These results suggest that the SED observed during the outburst was dominated by a single emission zone, where synchrotron self-Compton (SSC) processes played a primary role. Since single-zone SSC models have typically fewer free parameters than multizone alternatives, they are a powerful probe of the physical conditions of the high-energy emitting regions. Therefore, observing SSC radiation even in CSS sources improves our understanding of the production of high-energy radiation in AGN jets.}, archive = {J_ApJ}, author = {Federica Giacchino and Giovanni La Mura and Stefano Ciprini and Dario Gasparrini and Marcello Giroletti and Marco Laurenti}, doi = {10.3847/1538-4357/add150}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {99}, shortjournal = {The Astrophys. J.}, title = {Fermi-LAT discovery of a gamma-ray outburst from the peculiar compact steep spectrum radiogalaxy 3C 216}, volume = {986}, year = {2025}, }
• (2025). Nature of ultralong period radio transients: Could they be strange dwarf pulsars?. ApJ, 986(1), 98. (www)

  @article{ , abstract = {Ultralong period radio transients (ULPTs), with periods of thousands of seconds, challenge conventional pulsar models. We propose that these isolated sources are strange dwarf (SD) pulsars—compact objects with a strange quark matter core surrounded by a normal matter crust. We develop a theoretical framework for SD pulsars and apply it to four known isolated ULPTs: GLEAM-X J162759.5–523504.3, GPM J1839–10, ASKAP J1832–0911 (DART J1832–0911), and ASKAP J193505.1+214841.0 (ASKAP J1935+2148). Our analysis shows that SD pulsars naturally explain both the ultralong periods and coherent radio emission of these sources, which occupy a distinctive region in the magnetic field–period diagram. We find that these objects have surface magnetic fields ranging from 10 6 to 10 10 G, with a consistent lower bound near 10 6 G that suggests a fundamental threshold for pair production in these magnetospheres. Their radio emission efficiencies ( η rad,rot ≈ 10 −4 –10 −2 ) align with those of normal pulsars despite their extreme periods. ASKAP J1935+2148 represents a boundary case, positioned below the theoretical death line but still radio active, offering crucial insights into emission mechanisms at extreme periods. The observed X-ray properties of ASKAP J1832–0911, including its two-component spectrum and synchronous X-ray/radio variability, strongly support the SD pulsar model. This framework provides a unified explanation for ULPTs and has significant implications for understanding exotic dense matter in compact objects.}, archive = {J_ApJ}, author = {Xia Zhou and Abdusattar Kurban and Wen-Tong Liu and Na Wang and Ya-Jing Yuan}, doi = {10.3847/1538-4357/add268}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {98}, shortjournal = {The Astrophys. J.}, title = {Nature of ultralong period radio transients: Could they be strange dwarf pulsars?}, volume = {986}, year = {2025}, }
• (2025). Spectral analysis of cygnus X-3 using simultaneous AstroSat and insight-HXMT observations. ApJ, 986(1), 97. (www)

  @article{ , abstract = {We present the results from a spectral analysis of Cygnus X-3 using simultaneous data from AstroSat and Insight-HXMT during its soft state. A pure reflection spectrum, including emission lines of iron, silicon, and sulfur, provides a good fit to the spectral data. An orbital phase-resolved analysis shows no significant spectral parameter variations, except for the normalization. Leveraging IXPE polarization results, we model using a funnel-shaped geometry and estimate the scattered flux and observed polarization for various funnel parameters and observer inclinations. We consider two scenarios: reflection from the funnel walls and scattering by gas within the funnel. Our results reconfirm previous findings, showing that reflection can produce a high polarization degree (PD) of 23%, but not a low PD of 12%. Conversely, scattering can produce a PD of 10%–12%, but not as high as 23% for a fixed observer inclination of 30 ∘ . The scattering results align with previous findings without absorption, but with absorption, PD drops significantly with increasing funnel opening angle. Thus, we can identify common funnel parameters that can produce the different observed PDs in the soft and hard states. The intrinsic luminosity of the source was estimated by comparing the results from a plane disk and the funnel model, which was found to be ∼7 × 10 40 erg s −1 for 12% PD (scattering) and ∼5 × 10 41 erg s −1 for 23% PD (reflection). However, for the reflection model, the luminosity may decrease to ∼ 10 40 erg s −1 when the 23% PD observed is taken as a lower limit.}, archive = {J_ApJ}, author = {Suraj K. Chaurasia and Gitika Mall and Ruchika Dhaka and Ranjeev Misra and Amit Pathak}, doi = {10.3847/1538-4357/add33f}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {97}, shortjournal = {The Astrophys. J.}, title = {Spectral analysis of cygnus X-3 using simultaneous AstroSat and insight-HXMT observations}, volume = {986}, year = {2025}, }
• (2025). Mass of cepheid v350 sgr incorporating interferometry and the companion mass. ApJ, 986(1), 96. (www)

  @article{ , abstract = {The system V350 Sgr has a classical Cepheid for the primary. Interferometry is presented for the system, and the full orbit is determined. The mass of the companion has been determined from an International Ultraviolet Explorer spectrum and comparison with the mass–temperature relation from detached eclipsing binaries. Combined with the mass of the companion (2.6 ± 0.2 M ⊙ ), the mass of the Cepheid is determined to be 4.7 ± 0.8 M ⊙ . For systems with less complete information, Cepheid masses can be determined from a single-lined spectroscopic orbit, Gaia proper motion anomalies, and the mass of the companion from the ultraviolet. Uncertainties resulting from different approaches to mass determination are discussed and are expected to be reduced after the Gaia DR4 release. Temperatures for Morgan–Keenan standard stars from the ultraviolet are also provided.}, archive = {J_ApJ}, author = {Nancy Remage Evans and Alexandre Gallenne and Pierre Kervella and H. Moritz Günther and Joanna Kuraszkiewicz and Richard I. Anderson and Charles Proffitt and Antoine Mérand and Boris Trahin and Giordano Viviani and Shreeya Shetye}, doi = {10.3847/1538-4357/add7dc}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {96}, shortjournal = {The Astrophys. J.}, title = {Mass of cepheid v350 sgr incorporating interferometry and the companion mass}, volume = {986}, year = {2025}, }
• (2025). A successful sheared-arcade eruption triggered by a failed erupted small filament. ApJ, 986(1), 95. (www)

  @article{ , abstract = {In this work, we analyze a successful eruption, accompanied by an X5.4-class flare in active region 11429. The eruptive structure is an elongated hot structure, with two curved brightenings below it. Additionally, we find that snail-shell-shaped flare loops are formed at the end of the flare, with a filament channel beneath the loops that implies a magnetic flux rope structure. The flare ribbons indicate a highly complex eruption process. During the eruption, using Global Oscillation Network Group data, we find a small filament that exists before and after the eruption. We reproduce the eruption using a full thermodynamic magnetohydrodynamic simulation, with the purpose to illustrate the mechanisms of the eruption. The small magnetic flux rope continuously rises due to arcade–arcade to rope–flare loop reconnection below, compressing the sheared magnetic arcades above. Slipping reconnection between the upper sheared magnetic arcades leads to the formation of new sheared magnetic arcades, resulting in a successful eruption. Simultaneously, the newly formed snail-shell-shaped flare loops constrain the elevation of the original magnetic flux rope below, implying that the original magnetic flux rope is not the eruptive structure of this successful eruption. Instead, the sheared magnetic arcades produced by the upper slipping reconnection above the original flux rope is the eruptive structure involved.}, archive = {J_ApJ}, author = {Wentai Fu and Yiwei Ni and Jinhan Guo and Yang Guo and P. F. Chen and Mingde Ding}, doi = {10.3847/1538-4357/add88e}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {95}, shortjournal = {The Astrophys. J.}, title = {A successful sheared-arcade eruption triggered by a failed erupted small filament}, volume = {986}, year = {2025}, }
• (2025). Missing titanium in the asymmetric supernova remnant w 49B. ApJ, 986(1), 94. (www)

  @article{ , abstract = {The progenitor of the W 49B supernova remnant is still under debate. One of the candidates is a jet-driven core-collapse supernova. In such a highly asymmetric explosion, a strong α -rich freeze-out is expected in local high-entropy regions, which should enrich elements synthesized by the capture of α -particles such as 44 Ti and 48 Cr (decaying to 44 Ca and 48 Ti, respectively). In the present work, in order to infer the progenitor of the W 49B remnant, we constrain the amount of stable Ti ( 48 Ti) synthesized, using Suzaku observations. We found no firm evidence for the Ti line and set the upper limit of M Ti / M Fe < 9.9 × 10 −4 (99% limit using Xspec/AtomDB) and M Ti / M Fe < 5.8 × 10 −4 (99% limit using SPEX). Our limits can exclude almost all core-collapse supernova models, suggesting that a Type Ia supernova from a near-Chandrasekhar-mass white dwarf is the most favorable candidate for the origin of W 49B. Future observations with X-ray microcalorimeter missions, such as XRISM, will give us a stronger constraint on the progenitor.}, archive = {J_ApJ}, author = {Toshiki Sato and Makoto Sawada and Keiichi Maeda and John P. Hughes and Brian J. Williams}, doi = {10.3847/1538-4357/add932}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {94}, shortjournal = {The Astrophys. J.}, title = {Missing titanium in the asymmetric supernova remnant w 49B}, volume = {986}, year = {2025}, }
• (2025). Methods to test the source of the extreme gas motions in WS 35. ApJ, 986(1), 93. (www)

  @article{ , abstract = {We present theoretical arguments toward the plausibility of a stellar wind to explain the 16,000 km s −1 line broadening in the optical spectra of WS 35, the central star in the Pa 30 nebula. The wind model is discussed in the context of super-Eddington flows. We argue that WS 35 potentially occupies a new regime of wind driving theory as the first metal-only wind. This framework provides a promising avenue for explaining the high-speed flow. We further describe how future radio observations can provide an independent test of the spherical wind scenario. A magnetically channeled wind would likely produce a relatively flat and bright radio spectral energy distribution. By contrast, a spherical wind should result in a thermal radio spectrum with a canonical continuum slope of ν 0.6 , and a brightness level consistent with the currently predicted mass-loss rate.}, archive = {J_ApJ}, author = {Sean J. Gunderson and Richard Ignace and Walter W. Golay}, doi = {10.3847/1538-4357/addb46}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {93}, shortjournal = {The Astrophys. J.}, title = {Methods to test the source of the extreme gas motions in WS 35}, volume = {986}, year = {2025}, }
• (2025). Global simulations of gravitational instability in protostellar disks with full radiation transport. II. locality of gravitoturbulence, clumpy spirals, and implications for observable substructure. ApJ, 986(1), 92. (www)

  @article{ , abstract = {Spiral perturbations in a gravitationally unstable accretion disk regulate disk evolution through angular momentum transport and heating and provide an observational signature of gravitational instability (GI). We use global 3D simulations to systematically characterize and understand these spiral perturbations. The spiral perturbations and the resulting transport are overall insensitive to the cooling type, with the exception that radiative cooling, especially in the optically thick regime, reduces the amplitude of temperature perturbations. Spiral perturbations are localized around corotation, allowing transport to be approximated by a local α viscosity to zeroth order in aspect ratio ( H / R ), but only after averaging over multiple orbits in time and/or multiple scale heights in space. Meanwhile, large-amplitude perturbations from strong gravitoturbulence can cause { \mathcal O }({\alpha }^{1/2}) deviation in the cooling rate of the disk. We develop empirical prescriptions for the angular momentum transport, heating, and cooling in a gravitoturbulent disk that capture the deviation from a viscous, unperturbed disk to first order in H / R and α 1/2 . The spiral perturbations in saturated gravitoturbulence are clumpy, with dense clumps forming through the nonlinear coupling between multiple modes at different m . Observationally, the clumpy gravitoturbulence produced by saturated GI can be mistaken with observational noise or embedded companions, especially under finite resolution. Meanwhile, grand-design spirals with m -fold symmetry may be uncommon among disks in saturated gravitoturbulence, and we speculate that they may instead be a signature of recently triggered or decaying GI.}, archive = {J_ApJ}, author = {Wenrui Xu and Yan-Fei Jiang and Matthew W. Kunz and James M. Stone}, doi = {10.3847/1538-4357/add14b}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {92}, shortjournal = {The Astrophys. J.}, title = {Global simulations of gravitational instability in protostellar disks with full radiation transport. II. locality of gravitoturbulence, clumpy spirals, and implications for observable substructure}, volume = {986}, year = {2025}, }
• (2025). Global simulations of gravitational instability in protostellar disks with full radiation transport. i. stochastic fragmentation with optical-depth-dependent rate and universal fragment mass. ApJ, 986(1), 91. (www)

  @article{ , abstract = {Fragmentation in a gravitationally unstable accretion disk can be an important pathway for forming stellar/planetary companions. To characterize quantitatively the condition for and outcome of fragmentation under realistic thermodynamics, we perform global 3D simulations of gravitationally unstable disks at various cooling rates and cooling types, including the first global simulations of gravitational instability that employ full radiation transport. We find that fragmentation is a stochastic process, with the fragment generation rate per disk area p frag showing an exponential dependence on the parameter β ≡ Ω K t cool , where Ω K is the Keplerian rotation frequency, and t cool is the average cooling timescale. Compared to a prescribed constant β , radiative cooling in the optically thin/thick regime makes p frag decrease slower/faster in β ; the critical β corresponding to ∼1 fragment per orbit is ≈3, 5, and 2 for constant β , optically thin, and optically thick cooling, respectively. The distribution function of the initial fragment mass is remarkably insensitive to disk thermodynamics. Regardless of cooling rate and optical depth, the typical initial fragment mass is m frag ≈ 40 M tot h 3 , with M tot being the total (star+disk) mass and h = H / R being the disk aspect ratio. Applying this result to typical Class 0/I protostellar disks, we find m frag ∼ 20 M J , suggesting that fragmentation more likely forms brown dwarfs. Given the finite width of the m frag distribution, forming massive planets is also possible.}, archive = {J_ApJ}, author = {Wenrui Xu and Yan-Fei Jiang and Matthew W. Kunz and James M. Stone}, doi = {10.3847/1538-4357/add14a}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {91}, shortjournal = {The Astrophys. J.}, title = {Global simulations of gravitational instability in protostellar disks with full radiation transport. i. stochastic fragmentation with optical-depth-dependent rate and universal fragment mass}, volume = {986}, year = {2025}, }
• (2025). Comparison of bar formation mechanisms. II. does a tidally induced bar grow faster than an internally developed bar?. ApJ, 986(1), 90. (www)

  @article{ , abstract = {Bar structures can form internally due to the instability of their host galaxies or externally due to perturbations from other galaxies. We systematically quantify the growth timescales ( τ bar ) of bars formed through these two mechanisms with a series of controlled N -body simulations. In galaxies susceptible to bar instability, tidally induced bars display τ bar values comparable to those of internally developed bars within the same disk. Tidal perturbations promote (delay) bar formation by advancing (postponing) its onset, but the growth rate of the bar structure remains largely unchanged. In these interaction scenarios, the bar formation is still driven primarily by the galaxy's internal nature, which remains unaffected by tidal perturbations. As the external perturbation wave reaches the galaxy's center, it evokes a "seed bar" that is then swing amplified. In this scenario, the onset of bar formation is advanced. Conversely, bar formation may be delayed if the external perturbation wave is out of phase with the preexisting spontaneously developed "seed bar," which causes destructive interference and limits bar growth. In the hot disk model that resists bar formation in isolation, the τ bar of the tidally forced bar correlates with the strength of the perturbation. The bar growth in this model deviates from an exponential profile and is better described by a linear function. The varied τ bar and the preference for linear growth contrast with bars formed in galaxies inherently susceptible to bar instability. These tidally forced bars may not adhere to the swing amplification mechanism that predicts exponential bar growth.}, archive = {J_ApJ}, author = {Yirui Zheng and Juntai Shen and Xufen Wu and Bin-Hui Chen}, doi = {10.3847/1538-4357/adcf93}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {90}, shortjournal = {The Astrophys. J.}, title = {Comparison of bar formation mechanisms. II. does a tidally induced bar grow faster than an internally developed bar?}, volume = {986}, year = {2025}, }
• (2025). Application of a low-dissipation HLLD approximate riemann solver to solar wind simulations. ApJ, 986(1), 89. (www)

  @article{ , abstract = {We investigate the steady-state solar wind in spherical coordinates using a low-dissipation Harten–Lax–van Leer-Discontinuities Riemann solver, in which the magnetic field is decomposed into an initial potential field B 0 and a time-dependent part B 1 . A constrained transport method is employed to effectively preserve the divergence-free condition, with the relative divergence errors maintained at truncation level throughout the simulation. The solar wind plasma and magnetic field equations are solved using a one-step MUSCL-type time integration scheme, combined with spacetime reconstruction at cell interfaces and edges. Prior to the solar wind simulation, the accuracy and robustness of the numerical method are verified through benchmark tests, including the smooth Alfvén wave problem, the Mach 800 dense MHD jet, and the MHD blast wave in spherical polar coordinates. The results confirm that the scheme achieves second-order accuracy and remains stable under challenging physical conditions. The validated scheme is then applied to simulate the structured solar wind during Carrington Rotation 2236, using Helioseismic and Magnetic Imager 720 s cadence line-of-sight magnetograms as input. The simulation successfully reproduces key large-scale solar wind features, such as polar and extended coronal holes, open and closed magnetic field regions, helmet streamers, pseudo-streamers, the heliospheric current sheet, and the spatial distribution of fast and slow solar wind streams. Comparisons with remote sensing observations and in situ measurements demonstrate reasonable agreement. However, discrepancies remain in the temporal variations of plasma parameters and the detailed structure of coronal holes, suggesting areas for further model refinement.}, archive = {J_ApJ}, author = {Caixia Li and Zhenning Shen and Man Zhang and Xueshang Feng}, doi = {10.3847/1538-4357/add018}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {89}, shortjournal = {The Astrophys. J.}, title = {Application of a low-dissipation HLLD approximate riemann solver to solar wind simulations}, volume = {986}, year = {2025}, }
• (2025). The galactic population of magnetars: A simulation-based inference study. ApJ, 986(1), 88. (www)

  @article{ , abstract = {Population synthesis modeling of the observed dynamical and physical properties of a population is a highly effective method for constraining the underlying birth parameters and evolutionary tracks. In this work, we apply a population synthesis model to the canonical magnetar population to gain insight into the parent population. We utilize simulation-based inference to reproduce the observed magnetar population with a model that takes into account the secular evolution of the force-free magnetosphere and magnetic field decay simultaneously and self-consistently. Our observational constraints are such that no magnetar is detected through their persistent emission when convolving the simulated populations with the XMM-Newton EPIC-pn Galactic plane observations, and that all of the ∼30 known magnetars are discovered through their bursting activity in the last ∼50 yr. Under these constraints, we find, within 95% credible intervals, the birth rate of magnetars to be 1.{8}_{-0.6}^{+2.6} kyr −1 , leading to having 10.{7}_{-4.4}^{+18.8} % of neutron stars born as magnetars. We also find a mean magnetic field at birth ( μ b is in T) {\mathrm{log}}\,\left({\mu }_{b}\right)=10.{2}_{-0.2}^{+0.1} , a magnetic field decay slope {\alpha }_{d}=1.{9}_{-1.3}^{+0.9} , and timescale {\tau }_{d}=17.{9}_{-14.5}^{+24.1} kyr, in broad agreement with previous estimates. We conclude this study by exploring detection prospects: an all-sky survey with XMM-Newton would potentially allow around seven periodic detections of magnetars to be obtained, with approximately 150 magnetars exceeding XMM-Newton's flux threshold, and the upcoming AXIS experiment should allow these detections to be doubled.}, archive = {J_ApJ}, author = {M. Sautron and A. E. McEwen and G. Younes and J. Pétri and P. Beniamini and D. Huppenkothen}, doi = {10.3847/1538-4357/add0aa}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {88}, shortjournal = {The Astrophys. J.}, title = {The galactic population of magnetars: A simulation-based inference study}, volume = {986}, year = {2025}, }
• (2025). Deep ultraviolet, emission-line imaging of the makani galactic wind. ApJ, 986(1), 87. (www)

  @article{ , abstract = {The O vi 1032, 1038 Å line is a key probe of cooling gas in the circumgalactic medium (CGM) of galaxies but has been observed to date primarily in absorption along single sight lines. We present deep Hubble Space Telescope (HST) Solar Blind Channel of the Advanced Camera for Surveys observations of the compact, massive starburst Makani. Makani hosts a 100 kpc, [O ii ]-emitting galactic wind driven by two episodes of star formation over 400 Myr. We detect O vi and Ly α emission across the [O ii ] nebula with similar morphology and extent, out to r ≈ 50 kpc. Using differential narrowband imaging, we separate Ly α and O vi and show that the O vi emission is comparable in brightness to [O ii ], with L O VI = 4 × 10 42 erg s −1 . The similar hourglass morphology and size of [O ii ] and O vi implicate radiative cooling at T = 10 5.5 K in a hot–cold interface. This may occur as the T > 10 7 K CGM—or the hot fluid driving the wind—exchanges mass with the T ≈ 10 4 K clouds entrained in (or formed by) the wind. The optical/UV line ratios may be consistent with shock ionization, although uncertain attenuation and Ly α radiative transfer complicate the interpretation. The detection of O vi in Makani lies at the bleeding edge of the UV imaging capabilities of HST and provides a benchmark for future emission-line imaging of the CGM with a wide-area UV telescope.}, archive = {J_ApJ}, author = {Triet Ha and David S. N. Rupke and Shane Caraker and Jack Harper and Alison L. Coil and Miao Li and Christy A. Tremonti and Aleksandar M. Diamond-Stanic and James E. Geach and Ryan C. Hickox and Sean D. Johnson and Gene C. K. Leung and John Moustakas and Serena Perrotta and Gregory H. Rudnick and Paul H. Sell and Kelly E. Whalen}, doi = {10.3847/1538-4357/add0b5}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {87}, shortjournal = {The Astrophys. J.}, title = {Deep ultraviolet, emission-line imaging of the makani galactic wind}, volume = {986}, year = {2025}, }
• (2025). Dust growth in ALMA rings. II. dusty rossby wave instability. ApJ, 986(1), 86. (www)

  @article{ , abstract = {Annular substructures serve as ideal venues for planetesimal formation. In this series, we investigate the linear stage of dust growth within rings. The first paper in this series examines the global streaming instability, while this study focuses on the dusty Rossby wave instability (DRWI). To this end, we perform a linear analysis of the two-fluid equations on a background pressure bump, representing annular substructures. The spectral code D edalus is used to solve the linear eigenvalue problem. We identify two distinct DRWI modes: Type I, which originates from dust-modified gas RWI, and Type II, which results from dust-gas coupling. Type I and Type II modes never coexist for a given azimuthal wavenumber k y , but transition between each other as k y varies. Type I modes are driven by the advection of background vorticity, and Type II modes possess two waves: Rossby waves, driven by advection, and thin waves, driven by dust-gas drag. Finally, we assess the relevance of DRWI in Atacama Large Millimeter/submillimeter Array (ALMA) rings using DSHARP sources. Our findings suggest that Type I modes could explain the absence of azimuthal asymmetries in many ALMA disks, whereas Type II modes are entirely absent in all eight observed rings, implying that unresolved narrow rings or alternative mechanisms may play a role in dust growth within annular substructures.}, archive = {J_ApJ}, author = {Can Cui and Konstantin Gerbig and Ya-Ping Li and Ziyan Xu and Rixin Li and Cong Yu and Min-Kai Lin and Feng Yuan}, doi = {10.3847/1538-4357/add146}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {86}, shortjournal = {The Astrophys. J.}, title = {Dust growth in ALMA rings. II. dusty rossby wave instability}, volume = {986}, year = {2025}, }
• (2025). From larger-scale cold-gas angular momentum environments to galaxy star formation activity. ApJ, 986(1), 85. (www)

  @article{ , abstract = {We study the influence of the ambient large-scale cold-gas vorticity on the specific star formation rate (sSFR) of central galaxies with stellar masses of 10.0\lt {\mathrm{log}}\,{M}_{\ast }/{M}_{\odot }\lt 11.5 at z = 0, using the TNG100 simulation. The cold-gas vorticity defined and calculated for gas with T gas < 2 × 10 4 K and on scales of ∼1 Mpc can well describe the angular motion of the ambient cold gas. We find crucial evidence for connections between the cold-gas vorticity and level of star formation activity, such that at any given halo mass (particularly below 10 13 M ⊙ ), galaxies living in higher cold-gas vorticity environments are generally less star-forming, regardless of their large-scale environment types (filament or knot), or star formation states (star-forming or quenched). In particular, at a fixed halo mass scale of 10 12 –10 13 M ⊙ , the median sSFR of galaxies living in environments with the top 30% cold-gas vorticity is ∼0.5 dex below that of galaxies living in environments with the bottom 30% cold-gas vorticity. At any fixed halo mass scale, cold-gas vorticities around filament galaxies are generally higher than those around knot galaxies, consistent with the fact that filament galaxies have lower sSFRs than knot galaxies. This large-scale cold-gas vorticity is highly connected to the orbital angular momentum of neighboring galaxies up to a distance of ∼500 kpc, indicating their common origin and a possible angular momentum inheritance/modulation from the latter to the former. The negative modulation by the environmental vorticity on galaxy star formation is only significantly observed for the cold gas, indicating the unique role of cold-gas angular momentum.}, archive = {J_ApJ}, author = {Sen Wang and Dandan Xu and Shengdong Lu}, doi = {10.3847/1538-4357/add155}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {85}, shortjournal = {The Astrophys. J.}, title = {From larger-scale cold-gas angular momentum environments to galaxy star formation activity}, volume = {986}, year = {2025}, }
• (2025). Stellar tidal disruptions by newborn neutron stars or black holes: A mechanism for hydrogen-poor (Super)luminous supernovae and fast blue optical transients. ApJ, 986(1), 84. (www)

  @article{ , abstract = {Hydrogen-poor supernovae (SNe) of Type Ibc are explosions of massive stars that lost their hydrogen envelopes, typically due to interactions with a binary companion. We consider the case where the natal kick imparted to the neutron star (NS) or black hole (BH) remnant brings the compact object to a collision with a main-sequence companion, eventually leading to full tidal disruption of the companion. Subsequently, super-Eddington accretion onto the NS/BH launches a powerful, fast wind which collides with the SN ejecta and efficiently converts the kinetic energy of the wind into radiation. The radiation is reprocessed by the surrounding ejecta into a luminous (∼10 44 erg s −1 at peak), days to months-long transient with optical peaks from −19 to −21 mag, comparable to (super)luminous Type Ibc SNe and fast blue optical transients (FBOTs) such as AT2018cow. From a Monte Carlo analysis, we estimate the fraction of tidal disruptions following SNe in binaries to be ∼0.1%–1%, roughly compatible with the event rates of these luminous SNe. At the broad-brush level, our model reproduces the multiwavelength and spectral observations of FBOTs, and has the potential to explain peculiar features seen in some (super)luminous SNe that are difficult to reproduce by the conventional magnetar spin-down mechanism, such as late-time hydrogen lines, bumpy light curves, and prepeak excess.}, archive = {J_ApJ}, author = {Daichi Tsuna and Wenbin Lu}, doi = {10.3847/1538-4357/add158}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {84}, shortjournal = {The Astrophys. J.}, title = {Stellar tidal disruptions by newborn neutron stars or black holes: A mechanism for hydrogen-poor (Super)luminous supernovae and fast blue optical transients}, volume = {986}, year = {2025}, }
• (2025). Stellar ages: A code to infer properties of stellar populations. ApJ, 986(1), 83. (www)

  @article{ , abstract = {We present a novel statistical algorithm, Stellar Ages, which currently infers the age, metallicity, and extinction posterior distributions of stellar populations from their magnitudes. While this paper focuses on these parameters, the framework is readily adaptable to include additional properties, such as rotation, in future work. Historical age-dating techniques either model individual stars or populations of stars, often sacrificing population context or precision for individual estimates. Stellar Ages does both, combining the strengths of these approaches to provide precise individual ages for stars while leveraging population-level constraints. We verify the algorithm's capabilities by determining the age of synthetic stellar populations and actual stellar populations surrounding a nearby supernova, SN 2004dj. In addition to inferring an age, we infer a progenitor mass consistent with direct observations of the precursor star. The median age inferred from the brightest nearby stars is {\mathrm{log}}_{10} (Age yr −1 ) = 7.1{9}_{-0.13}^{+0.10} , and its corresponding progenitor mass is 13.9{5}_{-1.96}^{+3.33} M ⊙ .}, archive = {J_ApJ}, author = {Joseph J. Guzman and Jeremiah W. Murphy and Andrés F. Barrientos and Benjamin F. Williams and Julianne J. Dalcanton}, doi = {10.3847/1538-4357/add265}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {83}, shortjournal = {The Astrophys. J.}, title = {Stellar ages: A code to infer properties of stellar populations}, volume = {986}, year = {2025}, }
• (2025). The role of high-mass stellar binaries in the formation of high-mass black holes in dense star clusters. ApJ, 986(1), 82. (www)

  @article{ , abstract = {Recent detections of gravitational waves from mergers of binary black holes (BBHs) with premerger source-frame individual masses in the so-called upper mass gap, expected due to (pulsational) pair instability supernovae ((P)PISNe), have created immense interest in the astrophysical production of high-mass black holes (BHs). Previous studies show that high-mass BHs may be produced via repeated BBH mergers inside dense star clusters. Alternatively, inside dense star clusters, stars with unusually low core-to-envelope mass ratios can form via mergers of high-mass stars, which then can avoid (P)PISN, but produce high-mass BHs via mass fallback. We simulate detailed star-by-star multiphysics models of dense star clusters using the Monte Carlo cluster evolution code CMC , to investigate the role of primordial binary fraction among high-mass stars (≥15 M ⊙ ) on the formation of high-mass BHs. We vary the high-mass stellar binary fraction ( {f}_{{\rm{b}},15}^{{\prime} } ) while keeping all other initial properties, including the population of high-mass stars, unchanged. We find that the number of high-mass BHs, as well as the mass of the most massive BH formed via stellar core collapse are proportional to {f}_{{\rm{b}},15}^{{\prime} } . In contrast, there is no correlation between {f}_{{\rm{b}},15}^{{\prime} } and the number of high-mass BHs formed via BH–BH mergers. Since the total production of high-mass BHs is dominated by BH–BH mergers in old clusters, the overall number of high-mass BHs produced over the typical lifetime of globular clusters is insensitive to {f}_{{\rm{b}},15}^{{\prime} } . We study the differences in the demographics of BH–BH mergers and their implications for LIGO–Virgo–Kagra detections as a function of {f}_{{\rm{b}},15}^{{\prime} } .}, archive = {J_ApJ}, author = {Ambreesh Khurana and Sourav Chatterjee}, doi = {10.3847/1538-4357/add337}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {82}, shortjournal = {The Astrophys. J.}, title = {The role of high-mass stellar binaries in the formation of high-mass black holes in dense star clusters}, volume = {986}, year = {2025}, }
• (2025). Testing X-ray reprocessing and mapping the soft excess of NGC 7469 with NICER. ApJ, 986(1), 81. (www)

  @article{ , abstract = {We present an X-ray/UV reverberation analysis of NGC 7469 across 210 days, using daily NICER observations with contemporaneous monitoring by Swift UVOT+XRT. We model the X-ray spectrum with a power-law continuum and a soft excess during each NICER epoch. These emission sources demonstrate correlated flux variability with a lag consistent with zero days. We find that the power-law emission is consistent with a compact X-ray corona, and that the soft excess can be explained by reflected coronal emission from the inner accretion disk. We test the relationship between changes in the flux of the X-ray corona and the UVW2 continuum, finding strong correlation and a negative X-ray lag of less than 1 day. This is consistent with a scenario in which the X-ray corona drives the UVW2 light curve through thermal reprocessing.}, archive = {J_ApJ}, author = {Ethan R. Partington and Edward M. Cackett and Rick Edelson and Keith Horne and Jake A. Miller and Aaron J. Barth and Jonathan Gelbord and Juan V. Hernández Santisteban}, doi = {10.3847/1538-4357/add3ef}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {81}, shortjournal = {The Astrophys. J.}, title = {Testing X-ray reprocessing and mapping the soft excess of NGC 7469 with NICER}, volume = {986}, year = {2025}, }
• (2025). The internal kinematics of NGC 2808 and its multiple populations. ApJ, 986(1), 80. (www)

  @article{ , abstract = {We use new Hubble Space Telescope observations coupled with archival data spanning a total temporal baseline of 17 yr to study the internal kinematics of the multiple populations in the globular cluster NGC 2808 from its center out to ∼8 half-light radii ( r h ). We detect different kinematical behaviors between the first- and second-generation populations. This is especially evident towards the external regions of the cluster, where second-generation stars are increasingly more radially anisotropic. Our results are in agreement with theoretical simulations that predict that second-generation stars, initially more concentrated in the inner regions, gradually diffuse outward and develop a stronger radially anisotropic velocity distribution with respect to the first-generation stars. We find the central regions of the cluster to exhibit a higher degree of energy equipartition than the outskirts: Our analysis reveals similar levels of energy equipartition in the radial and tangential components of the motion within about 4 r h , while outside 4 r h the data suggest that the equipartition level of the radial component of the velocity dispersion is slightly higher than that of the tangential component. Finally, we measured the dispersion of the angular momentum L z for the three main subpopulations along the main sequence, which provides further evidence of the differences in the velocity anisotropy of first-generation and second-generation stars and shows marginal evidence for the most extreme second-generation subpopulation being slightly more radially anisotropic than the other second-generation subpopulation.}, archive = {J_ApJ}, author = {M. Griggio and A. Bellini and F. I. Aros and E. Vesperini and M. Libralato and J. Anderson and H. Baumgardt and F. R. Ferraro and R. P. van der Marel and S. Raso and A. Renzini and A. Rest and R. E. Ryan}, doi = {10.3847/1538-4357/add3fd}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {80}, shortjournal = {The Astrophys. J.}, title = {The internal kinematics of NGC 2808 and its multiple populations}, volume = {986}, year = {2025}, }
• (2025). The outflow impact on the size of the narrow-line region among type 2 active galactic nuclei. ApJ, 986(1), 79. (www)

  @article{ , abstract = {We present a study of the gas kinematics in narrow-line regions (NLRs) of 2009 Type 2 active galactic nuclei (AGNs) at z < 0.34. We construct [O iii ] λ 5007 emission-line images using publicly available broadband images from the Sloan Digital Sky Survey (SDSS). The [O iii ] emission areas of the samples, measured down to a rest-frame isophote of 1.4 × 10 −15 erg s −1 cm −2 arcsec −2 , range from 3.7 up to 224 kpc 2 . With our broadband technique, we found a correlation between [O iii ] area and AGN luminosity inferred from the [O iii ] luminosity and the mid-infrared luminosity at rest-frame 15 μ m. The isophotal threshold used to determine the [O iii ] area affects the correlation strength in that a brighter isophote yields a stronger correlation between the [O iii ] area and AGN luminosity. The presence of gas outflows is examined by the ratio of the [O iii ] velocity dispersion to the stellar velocity dispersion ( σ [O iii ] / σ ⋆ > 1.4) using SDSS spectra. At a given luminosity, objects with and without outflows exhibit the same extent of [O iii ] emission. Their correlation between [O iii ] area and luminosity is almost identical. It is suggested that the size of NLRs is not affected by outflow mechanisms but rather by photoionization from the central AGNs.}, archive = {J_ApJ}, author = {Kantapon Jensangjun and Suraphong Yuma}, doi = {10.3847/1538-4357/add411}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {79}, shortjournal = {The Astrophys. J.}, title = {The outflow impact on the size of the narrow-line region among type 2 active galactic nuclei}, volume = {986}, year = {2025}, }
• (2025). Submillimeter observations of the white dwarf pulsar AR sco. ApJ, 986(1), 78. (www)

  @article{ , abstract = {AR Scorpii, the so-called white dwarf (WD) pulsar, contains a rapidly rotating magnetic WD ( P spin = 117.0564 s) interacting with a cool, red dwarf (RD) companion in a 3.56 hr orbit. It is a strong radio source with an inverted spectral index between 1 and 200 GHz that is indicative of synchrotron emission. This paper presents the first submillimeter observations of AR Scorpii using the Submillimeter Array, helping to fill a critical gap in the spectral energy distribution (SED) between 10 and 600 GHz. The average flux densities at 220 and 345 GHz are 124 and 86 mJy, respectively. The lower than expected flux density at 345 GHz suggests a break in the synchrotron emission at about 200 GHz. A periodogram analysis of the 220 GHz observations shows a modulation with an amplitude of ≈6% at a period of 58.26 s or at twice the spin frequency of the WD. This modulation is the first direct detection of the WD spin period at radio frequencies and implies that the synchrotron emission arises near the WD and and not from an interaction with the photosphere of the RD. A fit to the SED shows that the synchrotron emission arises from a small, low-density region with a magnetic field of 43 MG at a distance of 0.6 orbital radii from the WD. This result implies that AR Scorpii contains a weakly magnetic WD (∼15 MG) and not a strongly magnetic WD (∼500 MG) as previously asserted.}, archive = {J_ApJ}, author = {Paul E. Barrett and Mark A. Gurwell}, doi = {10.3847/1538-4357/add725}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {78}, shortjournal = {The Astrophys. J.}, title = {Submillimeter observations of the white dwarf pulsar AR sco}, volume = {986}, year = {2025}, }
• (2025). Assessing the role of large fullerenes as potential carriers of infrared emission plateaus. ApJ, 986(1), 77. (www)

  @article{ , abstract = {We investigate large fullerenes containing between 90 and 1750 carbon atoms and with radii ranging from 4.4 to 12.9 Å, and compare their computed emission spectra to Spitzer data for the fullerene-rich planetary nebulae SMP SMC 24 and SMP LMC 48 to assess their contribution to the broad infrared emission plateaus. The structures are computed without any bias using molecular dynamics simulations and contain mostly five- and six-membered rings, several seven-membered rings, and very few four- and eight-membered rings. Our largest structures consist of multishell fullerenes. The infrared spectra are calculated using the density-functional-based tight-binding theory. Their emission spectra exhibit broad plateaus from 6 to 10 μ m and from 14 to 20 μ m, whose 6–10/14–20 relative intensity ratios reach a maximum value for ∼200 carbons. The computed 6–10 μ m plateaus exhibit distinct subfeatures in agreement with the observations. The subfeatures with the largest intensities peak at 6.6 and 7.7–7.9 μ m. We assign these subfeatures to C–C stretching vibrations from the different types of rings arranged in many different ways. A comparison of the computed 6–10/14–20 μ m intensity ratios as a function of fullerene size and photon energy with the observed 6–10/14–20 μ m intensity ratio for SMP LMC 48 allows us to derive an upper bound of ∼150–200 carbons for the fullerene size.}, archive = {J_ApJ}, author = {A. Ricca and E. Peeters and J. Cami}, doi = {10.3847/1538-4357/adda2d}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {77}, shortjournal = {The Astrophys. J.}, title = {Assessing the role of large fullerenes as potential carriers of infrared emission plateaus}, volume = {986}, year = {2025}, }
• (2025). The interplay between dust dynamics and turbulence induced by the vertical shear instability. ApJ, 986(1), 76. (www)

  @article{ , abstract = {The interaction between gas and dust in protoplanetary disks (PPDs) plays a crucial role in setting the stage for planet formation. In particular, the streaming instability (SI) is well recognized as the mechanism for planetesimal formation out of this interaction. The outer region of PPDs is likely subject to the vertical shear instability (VSI), representing a major source of disk turbulence characterized by vertical corrugation that leads to strong dust stirring. In the meantime, the VSI turbulence in 3D generates vortices through the Rossby wave instability (RWI), which can trap dust and thereby promote dust concentration. In this study, we use the multifluid dust module in Athena++ to conduct 2D axisymmetric global simulations of PPDs with mesh refinement and 3D global simulations with modest resolution. In 2D, the VSI corrugation mode is weakened by dust back-reaction, while the SI can still survive regardless of initial conditions. Dust clumping occurs and is seeded by VSI-induced zonal flows. In 3D, dust can settle even more with increased dusty buoyancy, suppressing the VSI corrugation mode. Meanwhile, dust back-reaction enhances dust concentration in RWI vortices, though higher resolution is needed to assess dust clumping.}, archive = {J_ApJ}, author = {Pinghui Huang and Xue-Ning Bai}, doi = {10.3847/1538-4357/add345}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {76}, shortjournal = {The Astrophys. J.}, title = {The interplay between dust dynamics and turbulence induced by the vertical shear instability}, volume = {986}, year = {2025}, }
• (2025). Investigating the emission mechanism in the spatially resolved jets of two z ≈ 3 radio-loud quasars. ApJ, 986(1), 75. (www)

  @article{ , abstract = {This study focuses on high-redshift, z > 3, quasars where resolved X-ray jets remain underexplored in comparison to nearby sources. Building upon previous work, we identify and confirm extended kiloparsec-scale jets emission in two quasars (J1405+0415, z = 3.215; J1610+1811, z = 3.122) through meticulous analysis of Chandra X-ray data. To deepen our understanding, high-resolution radio follow-up observations were conducted to constrain relativistic parameters, providing valuable insights into the enthalpy flux of these high-redshift active galactic nucleus jets. The investigation specifically aims to test the X-ray emission mechanism in these quasars by exploring the inverse Compton scattering of cosmic microwave background photons by synchrotron-emitting electrons. Our novel method uses a prior to make a Bayesian estimate of the unknown angle of the jet to our line of sight, thus breaking the usual degeneracy of the bulk Lorentz factor and the Doppler beaming factor.}, archive = {J_ApJ}, author = {Jaya Maithil and Daniel A. Schwartz and Aneta Siemiginowska and Preeti Kharb and Diana M. Worrall and John F. C. Wardle and Giulia Migliori and Chi C. Cheung and Bradford Snios and Doug B. Gobeille and Herman L. Marshall and Mark Birkinshaw}, doi = {10.3847/1538-4357/adccc1}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {75}, shortjournal = {The Astrophys. J.}, title = {Investigating the emission mechanism in the spatially resolved jets of two z ≈ 3 radio-loud quasars}, volume = {986}, year = {2025}, }
• (2025). Generalized Te([O iii])–Te(He i) discrepancies in ionized nebulae: Possible evidence of case b deviations and temperature inhomogeneities. ApJ, 986(1), 74. (www)

  @article{ , abstract = {The physics of recombination lines in the He i singlet system is expected to be relatively simple, supported by accurate atomic models. We examine the intensities of He i singlets λ 3614, λ 3965, λ 5016, λ 6678, and λ 7281 and the triplet He i λ 5876 in various types of ionized nebulae and compare them with theoretical predictions to test the validity of the "Case B" recombination scenario and the assumption of thermal homogeneity. Our analysis includes 85 spectra from Galactic and extragalactic H ii regions, 90 from star-forming galaxies, and 218 from planetary nebulae, all compiled by the Deep Spectra of Ionized Regions Database Extended (DESIRED-E) project. By evaluating the ratios He i λ 7281/ λ 6678 and He i λ 7281/ λ 5876, we determine T e (He i ) and compare it with direct measurements of T e ([O iii ] λ 4363/ λ 5007). We find that T e (He i ) is systematically lower than T e ([O iii ]) across most objects and nebula types. Additionally, we identify a correlation between the abundance discrepancy factor (ADF(O 2+ )) and the difference T e ([O iii ]) – T e (He i ) for planetary nebulae. We explore two potential explanations: photon loss from n 1 P → 1 1 S transitions and temperature inhomogeneities. Deviations from "Case B" may indicate photon absorption by H i rather than He i and/or generalized ionizing photon escape, highlighting the need for detailed consideration of radiative transfer effects. If temperature inhomogeneities are widespread, identifying a common physical phenomenon affecting all ionized nebulae is crucial. Our results suggest that both scenarios can contribute to the observed discrepancies.}, archive = {J_ApJ}, author = {J. E. Méndez-Delgado and E. D. Skillman and E. Aver and C. Morisset and C. Esteban and J. García-Rojas and K. Kreckel and N. S. J. Rogers and F. F. Rosales-Ortega and K. Z. Arellano-Córdova and S. R. Flury and E. Reyes-Rodríguez and M. Orte-García and S. Tan}, doi = {10.3847/1538-4357/adc67a}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {74}, shortjournal = {The Astrophys. J.}, title = {Generalized Te([O iii])–Te(He i) discrepancies in ionized nebulae: Possible evidence of case b deviations and temperature inhomogeneities}, volume = {986}, year = {2025}, }
• (2025). Probing progression of heating through the lower flare atmosphere via high-cadence IRIS spectroscopy. ApJ, 986(1), 73. (www)

  @article{ , abstract = {Recent high-cadence flare campaigns by the Interface Region Imaging Spectrograph (IRIS) have offered new opportunities to study rapid processes characteristic of flare energy release, transport, and deposition. Here, we examine high-cadence chromospheric and transition region spectra acquired by IRIS during a C-class flare from 2022 September 25. Within the flare ribbon, the intensities of the Si iv 1402.77 Å, C ii 1334.53 Å and Mg ii k 2796.35 Å lines peaked at different times, with the transition region Si iv typically peaking before the chromospheric Mg ii line by 1–6 s. To understand the nature of these delays, we probed a grid of radiative hydrodynamic flare simulations heated by electron beams, thermal conduction-only, or Alfvén waves. Electron beam parameters were constrained by hard X-ray observations from the Gamma-ray Burst Monitor (GBM) onboard the Fermi spacecraft. Reproducing light curves where Si iv peaks precede those in Mg ii proved to be a challenge because only a subset of Fermi/GBM-constrained electron beam models were consistent with the observations. Light curves with relative timings consistent with the observations were found in simulations heated by either high-flux electron beams or by Alfvén waves, while the thermal conduction heating does not replicate the observed delays. Our analysis shows how delays between chromospheric and transition region emission pose tight constraints on flare models and properties of energy transport, highlighting the importance of obtaining very high-cadence data sets with IRIS and other observatories.}, archive = {J_ApJ}, author = {Juraj Lörinčík and Vanessa Polito and Graham S. Kerr and Laura A. Hayes and Alexander J. B. Russell}, doi = {10.3847/1538-4357/adccc8}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {73}, shortjournal = {The Astrophys. J.}, title = {Probing progression of heating through the lower flare atmosphere via high-cadence IRIS spectroscopy}, volume = {986}, year = {2025}, }
• (2025). Preliminary evidence for lensing-induced alignments of high-redshift galaxies in JWST-CEERS. ApJ, 986(1), 72. (www)

  @article{ , abstract = {The majority of low-mass ( {\mathrm{log}}_{10}{M}_{* }/{M}_{\odot }=9\mbox{--}10 ) galaxies at high redshift ( z > 1) appear elongated in projection. We use JWST-CEERS observations to explore the role of gravitational lensing in this puzzle. The typical galaxy–galaxy lensing shear γ ∼ 1% is too low to explain the predominance of elongated early galaxies with an ellipticity e ≈ 0.6. However, nonparametric quantile regression with Bayesian Additive Regression Trees (or BART) reveals hints of an excess of tangentially aligned source–lens pairs with γ > 10%. On larger scales, we also find evidence for weak-lensing shear. We rule out the null hypothesis of randomly oriented galaxies at ≳99% significance in multiple NIRCam chips, modules, and pointings. The number of such regions is small and attributable to chance, but coherent alignment patterns suggest otherwise. On the chip scale, the average complex ellipticity 〈 e 〉 ∼ 10% is nonnegligible and beyond the level of our point-spread function (PSF) uncertainties. The shear variance \langle {\overline{\gamma }}^{2}\rangle \sim 1{0}^{-3} is an order of magnitude above the conventional weak-lensing regime but is more sensitive to PSF systematics, intrinsic alignments, cosmic variance, and other biases. Taking it as an upper limit, the maximum implied "cosmic shear" is only a few percent and cannot explain the elongated shapes of early galaxies. The alignments themselves may arise from lensing by a protocluster or filament at z ∼ 0.75 where we find an overabundance of massive lens galaxies. We recommend a weak-lensing search for overdensities in "blank" deep fields with the James Webb Space Telescope and the Roman Space Telescope.}, archive = {J_ApJ}, author = {Viraj Pandya and Abraham Loeb and Elizabeth J. McGrath and Guillermo Barro and Steven L. Finkelstein and Henry C. Ferguson and Norman A. Grogin and Jeyhan S. Kartaltepe and Anton M. Koekemoer and Casey Papovich and Nor Pirzkal and L. Y. Aaron Yung}, doi = {10.3847/1538-4357/adcd78}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {72}, shortjournal = {The Astrophys. J.}, title = {Preliminary evidence for lensing-induced alignments of high-redshift galaxies in JWST-CEERS}, volume = {986}, year = {2025}, }
• (2025). Gravitationally induced explosive outflows. ApJ, 986(1), 71. (www)

  @article{ , abstract = {Over the past decade, there has been a significant increase in the reporting of extensive and luminous star-forming regions associated with explosive outflows. Nevertheless, there is still a lack of understanding of the possible physical mechanisms that produce such energetic and isotropic events. We propose a gravitational interaction as a likely mechanism that could trigger explosive outflows in dense star-forming regions. This could constrain the physical conditions that generate an explosive outflow produced by the close dynamical encounter of a runaway star with a clump cluster in dynamical equilibrium. We have produced a set of N -body simulations that account for the collision of a 10 M ⊙ stellar object with a cluster of particles with a mass that ranges from 0 to 50 M ⊙ . We propose a parameter to describe the interaction, the evaporation parameter, which describes the fraction of stars that become unbound. The main result is that, when the cluster mass is less than or up to a few times the stellar mass, the collision will produce an explosive outflow, ejecting a significant fraction of the cluster members with velocities larger than the impact velocity. All of our models produce an explosive outflow, with different characteristics, which increases the probability that a close encounter could be responsible for producing the observed flows.}, archive = {J_ApJ}, author = {P. R. Rivera-Ortiz and A. Rodríguez-González and J. Cantó and L. A. Zapata and L. Hernández-Martínez and E. Guzmán Ccolque and M. Fernández-López}, doi = {10.3847/1538-4357/adcecf}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {71}, shortjournal = {The Astrophys. J.}, title = {Gravitationally induced explosive outflows}, volume = {986}, year = {2025}, }
• (2025). Testing OH megamaser identification methods in h i surveys: Updated source-flagging algorithms and new detections in ALFALFA. ApJ, 986(1), 70. (www)

  @article{ , abstract = {OH megamasers (OHMs) are extragalactic masers found primarily in gas-rich galaxy major mergers. To date, only ∼120 OHMs have been cataloged since their discovery in 1982, and efforts to identify distinct characteristics of OHM host galaxies have remained inconclusive. As radio astronomy advances with next-generation telescopes and extensive 21 cm H i surveys, precursors to the Square Kilometre Array are expected to detect the 18 cm OH masing line with significantly increased frequency, potentially expanding the known OHM population tenfold. These detections, however, risk confusion with lower-redshift H i emitters unless accompanied by independent spectroscopic redshifts. Building on methods proposed by Roberts et al. for distinguishing these interloping OHMs via near- to mid-IR photometry and emission line frequencies, we apply these techniques to data from the Arecibo Legacy Fast ALFA [Arecibo L -band Feed Array] (ALFALFA) survey and a preliminary Aperture Tile In Focus (Apertif) H i emission line catalog from the Westerbork Synthesis Radio Telescope. Our study, utilizing the Apache Point Observatory 3.5 m telescope to obtain optical spectroscopic redshifts of 142 candidates (107 from ALFALFA and 35 from Apertif), confirms five new OHM host galaxies and reidentifies two previously catalogued OHMs misclassified as H i emitters in ALFALFA. These findings support the predictions from Roberts et al. and underscore the evolving landscape of radio astronomy in the context of next-generation telescopes.}, archive = {J_ApJ}, author = {Hayley Roberts and Jeremy Darling and Kelley M. Hess and Andrew J. Baker and Elizabeth A. K. Adams and Helga Dénes}, doi = {10.3847/1538-4357/adcedc}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {70}, shortjournal = {The Astrophys. J.}, title = {Testing OH megamaser identification methods in h i surveys: Updated source-flagging algorithms and new detections in ALFALFA}, volume = {986}, year = {2025}, }
• (2025). Searching for correlations between satellite galaxy populations and the cold circumgalactic medium around TNG50 galaxies. ApJ, 986(1), 69. (www)

  @article{ , abstract = {We investigate the impact of satellites, a potentially important contributor toward the cold gas assembly of a halo, on the cold gas budgets of 197 TNG50 simulated halos with masses of 10 10.85 ≤ M 200 c / M ⊙ ≤ 10 12.24 at z = 0. To highlight the effect of satellites, we split the sample into three mass bins. We find that the total number of satellites, total mass of satellites, number of massive satellites, and stellar mass of the most massive satellite all correlate with the cold gas mass in halos. The total number of satellites (stellar mass of the most massive satellite) correlates the most with the halo cold gas mass for low (middle) mass halos. The number of massive or observable satellites correlates with cold gas mass in a similar manner as the total number of satellites. Our findings can, therefore, be used to guide future observers to focus on the link between the number of observable satellites and the amount of cold gas in a halo. Despite this correlation, we find that much of the cold gas lies far from the satellites. This leads us to conclude that satellites are unlikely to be the main supplier for cold gas in halos. However, we discuss how they may act in tandem with other sources, such that the satellite population correlates with the total cold gas in their host halo.}, archive = {J_ApJ}, author = {Mitali Damle and Stephanie Tonnesen and Martin Sparre and Philipp Richter}, doi = {10.3847/1538-4357/adcee9}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {69}, shortjournal = {The Astrophys. J.}, title = {Searching for correlations between satellite galaxy populations and the cold circumgalactic medium around TNG50 galaxies}, volume = {986}, year = {2025}, }
• (2025). SN 2023ehl: A normal type ia supernova with high-velocity features. ApJ, 986(1), 68. (www)

  @article{ , abstract = {SN 2023ehl, a normal Type Ia supernova with a typical decline rate, was discovered in the galaxy UGC 11555 and offers valuable insights into the explosion mechanisms of white dwarfs. We present a detailed analysis of SN 2023ehl, including spectroscopic and photometric observations. The supernova exhibits high-velocity features in its ejecta, which are crucial for understanding the physical processes during the explosion. We compared the light curves of SN 2023ehl with other well-observed Type Ia supernovae, finding similarities in their evolution. The line strength ratio R (Si ii ) was calculated to be 0.17 ± 0.04, indicating a higher photospheric temperature compared to other supernovae. The maximum quasi-bolometric luminosity was determined to be 1.52 × 10 43 erg s −1 , and the synthesized 56 Ni mass was estimated at 0.77 ± 0.05 M ⊙ . The photospheric velocity at B -band maximum light was measured as 10,150 ± 240 km s −1 , classifying SN 2023ehl as a normal velocity Type Ia supernova. Our analysis suggests that SN 2023ehl aligns more with both the gravitationally confined detonation, providing a comprehensive view of the diversity and complexity of Type Ia supernovae.}, archive = {J_ApJ}, author = {Xiangyun Zeng and Lei Hu and Sheng Zheng and Xiaolong Li and Xiaoyu Luo and Sai Li and D. Andrew Howell and Yize Dong and Stefano Valenti and Liping Fu and Cheng Liu and Shiyu Li and Shuguang Zeng and Yao Huang and Yijing Luo and K. Azalee Bostroem and Curtis McCully and Ali Esamdin and Moira Andrews and Joseph R. Farah and Megan Newsome and Giacomo Terreran and Estefania Padilla Gonzalez and Emily Hoang and Aravind Pazhayath Ravi and Darshana Mehta and Nicolas Meza Retamal and Peng Zhang and Rongjun Zhang and Wang Li and Haonan Zhang}, doi = {10.3847/1538-4357/adcf1b}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {68}, shortjournal = {The Astrophys. J.}, title = {SN 2023ehl: A normal type ia supernova with high-velocity features}, volume = {986}, year = {2025}, }
• (2025). An extended closure relation by LightGBM for neutrino radiation transport in core-collapse supernovae. ApJ, 986(1), 67. (www)

  @article{ , abstract = {We developed a machine learning model using LightGBM, one of the most popular gradient-boosting decision tree methods these days, to predict the Eddington tensor, or the second-order angular moment, for neutrino radiation transport in core-collapse supernova simulations. We use not only the zeroth and first moments of the neutrino distribution function in momentum space as in ordinary closure relations, but also information on the background matter configuration extensively. For training the model, we utilize some post-bounce snapshots from one of our previous Boltzmann radiation–hydrodynamics simulations; the Eddington tensor, as well as the zeroth and first angular moments, are calculated from the neutrino distribution function obtained in the simulation. LightGBM is light indeed, and its high efficiency in training enables us to feed a large number of features and figure out which features are more important than others. In this paper, we report the results of this feature engineering in addition to those of the training, validation, and generalization of our model. We find that the flux factor and nonlocal features are among the most relevant features; our LightGBM model can reproduce the Eddington factor better in general than the M1 closure relation, one of the most commonly employed algebraic closure relations at present; the generalization performance is also much improved from our previous model based on the deep neural network.}, archive = {J_ApJ}, author = {Shota Takahashi and Akira Harada and Shoichi Yamada}, doi = {10.3847/1538-4357/add0ae}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {67}, shortjournal = {The Astrophys. J.}, title = {An extended closure relation by LightGBM for neutrino radiation transport in core-collapse supernovae}, volume = {986}, year = {2025}, }
• (2025). A morphological study of AGN-host dwarf galaxies. ApJ, 986(1), 66. (www)

  @article{ , abstract = {The study of morphology in galaxies offers a convenient and quantitative method to measure the shapes and characteristics of galaxy light distribution that reflect the evolutionary history. For active galactic nucleus (AGN)-host dwarf galaxies, however, there is a lack of detailed studies of their morphologies. In this work, we compile a relatively large sample (∼400 members) of local AGN-host dwarf ( M ⋆ ≤ 10 9.5 M ⊙ and z < 0.055) galaxies selected via various methods. We use the grz bands images from DESI DR10 and the Python package statmorph to measure nonparametric coefficients. We also carry out visual inspection with the assistance of deep learning to classify these galaxies into early-type galaxies (ETGs), late-type galaxies (LTGs), and mergers, and find that about 37%, 44%, and 13% of the total sample sources are ETGs, LTGs, and mergers, respectively. In comparison to normal dwarf galaxies, AGN-host dwarfs have a higher probability to be LTGs, and a lower merger rate, indicating that mergers/interactions are not the primary driver of AGN activities. Among the subsamples selected with different methods, the Baldwin, Phillips & Terlevich sample has the highest fraction of ETGs, the variability sample consists of the largest fraction of LTGs, and the mid-IR sample contains the most mergers.}, archive = {J_ApJ}, author = {Jie Tian and Yinghe Zhao and Xiejin Li and Jinming Bai}, doi = {10.3847/1538-4357/add140}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {66}, shortjournal = {The Astrophys. J.}, title = {A morphological study of AGN-host dwarf galaxies}, volume = {986}, year = {2025}, }
• (2025). Empirical parametric model for venus plasma boundaries based on venus express data. ApJ, 986(1), 65. (www)

  @article{ , abstract = {Venus's induced magnetosphere is characterized by regions with different plasma and magnetic field properties, which are separated by plasma boundaries. These boundaries' locations and shapes vary with upstream solar wind conditions, and these variations have been characterized by several previous studies. In this study, we developed quantitative parametric models of the bow shock and ion composition boundary (ICB), which allow us to determine the location and shape of the boundaries given a set of upstream conditions. To quantitatively model these boundaries, we used a database of boundary crossings derived from plasma and magnetic field measurements by Venus Express. We modeled the bow shock as a conic section curve, which depends on the interplanetary magnetic field (IMF) magnitude and the solar wind proton flux. Furthermore, we considered the shock normal angle, the angle between the IMF and the local shock normal vector, to describe a quasi-perpendicular/quasi-parallel shock asymmetry. We modeled the dayside ICB as a half sphere that depends solely on the solar EUV flux and the solar wind proton flux. These parametric models are compared with models that average over upstream conditions; our bow shock parametric model improves the prediction accuracy by 16% and the ICB parametric model by 6%.}, archive = {J_ApJ}, author = {Umberto Rollero and Sebastián Rojas Mata and Tielong Zhang and Moa Persson and Sofia Bergman and Yoshifumi Futaana}, doi = {10.3847/1538-4357/add14d}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {65}, shortjournal = {The Astrophys. J.}, title = {Empirical parametric model for venus plasma boundaries based on venus express data}, volume = {986}, year = {2025}, }
• (2025). Fe xviii and fe xx forbidden lines observed by solar Orbiter/SPICE. ApJ, 986(1), 64. (www)

  @article{ , abstract = {The first simultaneous observations of the Fe xviii 974.86 Å and Fe xx 721.56 Å forbidden lines from the Spectral Imaging of the Coronal Environment (SPICE) spectrograph on Solar Orbiter are presented. The lines were observed from the postflare loops of an M2.5 class solar flare that peaked at 23:49 UT on 2024 March 23. The Fe xx /Fe xviii ratio is used to derive a temperature spacetime map for the flaring period, with values ranging from 8 to 20 MK. The map reveals repeated episodes of heating at the SPICE slit location over a 30 minute period. For one location with the brightest emission, the plasma cooled from 10 to 8 MK in 5 minutes, which is longer than the expected conductive cooling time of 170 s, suggesting continued background heating during the cooling period. Doppler shifts of between 0 and +10 km s −1 were obtained with precisions of 1–4 km s −1 , but the accuracies are lower due to uncertainties over the absolute wavelength calibration; hence, we cannot conclude there are plasma flows in the flare loops. The widths of the two lines were found to be close to the instrumental widths with no evidence of nonthermal broadening although this result is limited by the instrument resolution. The Fe xviii and Fe xx lines have high signal-to-noise with only a 5 s exposure time, demonstrating that the lines will be valuable for high-cadence flare studies with SPICE.}, archive = {J_ApJ}, author = {Peter R. Young and Andrew R. Inglis and Graham S. Kerr and Therese A. Kucera and Daniel F. Ryan}, doi = {10.3847/1538-4357/add339}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {64}, shortjournal = {The Astrophys. J.}, title = {Fe xviii and fe xx forbidden lines observed by solar Orbiter/SPICE}, volume = {986}, year = {2025}, }
• (2025). From pretransit to posteclipse: Investigating the impact of 3D temperature, chemistry, and dynamics on high-resolution emission spectra of the ultrahot jupiter WASP-76b. ApJ, 986(1), 63. (www)

  @article{ , abstract = {High-resolution spectroscopy has provided a wealth of information about the climate and composition of ultrahot Jupiters (UHJs). However, the 3D structure of their atmospheres makes observations more challenging to interpret, necessitating 3D forward-modeling studies. In this work, we model phase-dependent thermal emission spectra of the archetype UHJ WASP-76b to understand how the line strengths and Doppler shifts of Fe, CO, H 2 O, and OH evolve throughout the orbit. We postprocess outputs of the SPARC/MITgcm global circulation model with the 3D Monte Carlo radiative transfer code gCMCRT to simulate emission spectra at 36 orbital phases. We then cross correlate the spectra with different templates to obtain cross-correlation function and K p – V sys maps. For each species, our models produce consistently negative K p offsets in pre- and posteclipse, which are driven by planet rotation. The size of these offsets is similar to the equatorial rotation velocity of the planet. Furthermore, we demonstrate how the weak vertical temperature gradient on the nightside of UHJs mutes the absorption features of CO and H 2 O, which significantly hampers their detectability in pre- and posttransit. We also show that the K p and V sys offsets in pre- and posttransit are not always a measure of the line-of-sight velocities in the atmosphere. This is because the cross-correlation signal is a blend of dayside emission and nightside absorption features. Finally, we highlight that the observational uncertainty in the known orbital velocity of UHJs can be multiple kilometers per second, which makes it hard for certain targets to meaningfully report absolute K p offsets.}, archive = {J_ApJ}, author = {Joost P. Wardenier and Vivien Parmentier and Elspeth K. H. Lee and Michael R. Line}, doi = {10.3847/1538-4357/add341}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {63}, shortjournal = {The Astrophys. J.}, title = {From pretransit to posteclipse: Investigating the impact of 3D temperature, chemistry, and dynamics on high-resolution emission spectra of the ultrahot jupiter WASP-76b}, volume = {986}, year = {2025}, }
• (2025). Origin of the multiphase interstellar medium: The effects of turbulence and magnetic field. ApJ, 986(1), 62. (www)

  @article{ , abstract = {The interstellar medium (ISM) consists of multiphase gas, including the warm neutral medium (WNM), the unstable neutral medium (UNM), and the cold neutral medium (CNM). While significant attention has been devoted to understanding the WNM and CNM, the formation of a substantial fraction of the UNM, with temperatures ranging from a few hundred to a few thousand Kelvin, remains less well understood. In this study, we present 3D hydrodynamical and magnetohydrodynamic simulations of the turbulent multiphase ISM to investigate the roles of turbulence and magnetic fields in regulating the multiphase ISM. Our results confirm that turbulence is crucial in redistributing energy and producing the UNM. The turbulent mixing effect smooths the phase diagram, flattens the pressure–density relationship, and increases the fraction of gas in the UNM. We find magnetic fields not only contribute to sustaining the UNM but also influence the dynamics and distribution of gas across all phases. Magnetic fields introduce anisotropy to the turbulent cascade, reducing the efficiency of turbulent mixing in the direction perpendicular to the magnetic field. We find the anisotropy results in a less flat phase diagram compared to hydrodynamical cases. Furthermore, the inclusion of magnetic fields shallows the second-order velocity structure functions across multiple ISM phases, suggesting that more small-scale fluctuations are driven. These fluctuations contribute to the formation of the UNM by altering the energy cascade and thermodynamic properties of the gas. Our findings suggest that the combined effects of turbulence and magnetic fields are important in regulating the multiphase ISM.}, archive = {J_ApJ}, author = {Yue Hu}, doi = {10.3847/1538-4357/add731}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {62}, shortjournal = {The Astrophys. J.}, title = {Origin of the multiphase interstellar medium: The effects of turbulence and magnetic field}, volume = {986}, year = {2025}, }
• (2025). The use of binary black holes merging in active galactic nuclei disks for hubble constant measurements. ApJ, 986(1), 61. (www)

  @article{ , abstract = {We study the impact of environmental effects on the measurement of the Hubble constant ( H 0 ) from gravitational-wave (GW) observations of binary black hole mergers residing in active galactic nuclei (AGNs) near the central supermassive black hole. Using the potential hierarchical triple merger candidate GW190514–GW190521 in AGN J124942.3+344929 with its potential electromagnetic counterpart ZTF19abanrhr as a multimessenger case study, we demonstrate that environmental effects can be negligible for mergers at approximately tens to hundreds of Schwarzschild radii from the supermassive black hole. We find {H}_{0}=40.{9}_{-8.9}^{+19.3}\,{\rm{km}}\,{{\rm{s}}}^{-1}\,{{\rm{Mpc}}}^{-1} (median and 68% credible interval) under a flat prior and flat ΛCDM cosmology. Incorporating GW170817 prior information improves constraints to {H}_{0}=68.{8}_{-6.0}^{+7.7}\,{\rm{km}}\,{{\rm{s}}}^{-1}\,{{\rm{Mpc}}}^{-1} . We suggest that, in general, AGN environments could serve as viable laboratories for cosmological studies from GW observations where environmental effects remain below detection thresholds.}, archive = {J_ApJ}, author = {Guo-Peng Li and Xi-Long Fan}, doi = {10.3847/1538-4357/adda46}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {61}, shortjournal = {The Astrophys. J.}, title = {The use of binary black holes merging in active galactic nuclei disks for hubble constant measurements}, volume = {986}, year = {2025}, }
• (2025). Cosmic himalayas: The highest quasar density peak identified in a 10,000 deg2 sky with spatial discrepancies between galaxies, quasars, and IGM h i. ApJ, 986(1), 60. (www)

  @article{ , abstract = {We report the identification of a quasar overdensity in the BOSSJ0210 field, dubbed the Cosmic Himalayas, consisting of 11 quasars at z = 2.16−2.20, the densest overdensity of quasars (17 σ ) in the ∼10,000 deg 2 of the Sloan Digital Sky Survey (SDSS). We present the spatial distributions of galaxies and quasars and a H i absorption map of the intergalactic medium (IGM). On the map of 465 galaxies selected from the MAMMOTH-Subaru survey, we find two galaxy density peaks that do not fall on the quasar overdensity but instead exist at the northwest and southeast sides, approximately 25 h −1 comoving Mpc (cMpc) apart from the quasar overdensity. With a spatial resolution of 15 h −1 cMpc in projection, we produce a three-dimensional H i tomography map by the IGM Ly α forest in the spectra of 23 SDSS/eBOSS quasars behind the quasar overdensity. Surprisingly, the quasar overdensity coincides with neither an absorption peak nor a transmission peak of IGM H i but lies near the border separating opaque and transparent volumes, with the more luminous quasars located in an environment with less IGM H i . Hence, remarkably, the overdensity region traced by the 11 quasars, albeit all in coherently active states, has no clear coincidence with peaks of galaxies or H i absorption densities. Current physical scenarios with mixtures of H i overdensities and quasar photoionization cannot fully interpret the emergence of the Cosmic Himalayas, suggesting this peculiar structure is an excellent laboratory to unveil the interplay between galaxies, quasars, and the IGM.}, archive = {J_ApJ}, author = {Yongming Liang and Masami Ouchi and Dongsheng Sun and Nobunari Kashikawa and Zheng Cai and Sebastiano Cantalupo and Kentaro Nagamine and Hidenobu Yajima and Takanobu Kirihara and Haibin Zhang and Mingyu Li and Rhythm Shimakawa and Xiaohui Fan and Kei Ito and Masayuki Tanaka and Yuichi Harikane and J. Xavier Prochaska and Andrea Travascio and Weichen Wang and Martin Elvis and Giuseppina Fabbiano and Junya Arita and Masafusa Onoue and John D. Silverman and Dong Dong Shi and Fangxia An and Takuma Izumi and Kazuhiro Shimasaku and Hisakazu Uchiyama and Chenghao Zhu}, doi = {10.3847/1538-4357/adc1bb}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {60}, shortjournal = {The Astrophys. J.}, title = {Cosmic himalayas: The highest quasar density peak identified in a 10,000 deg2 sky with spatial discrepancies between galaxies, quasars, and IGM h i}, volume = {986}, year = {2025}, }
• (2025). ChronoFlow: A data-driven model for gyrochronology. ApJ, 986(1), 59. (www)

  @article{ , abstract = {Gyrochronology is a technique for constraining stellar ages using rotation periods, which change over a star's main-sequence (MS) lifetime due to magnetic braking. This technique shows promise for MS FGKM stars, where other methods are imprecise. However, the observed dispersion in rotation rates for similar coeval stars has historically been difficult to characterize. To properly understand this complexity, we have assembled the largest standardized data catalog of rotators in open clusters to date, consisting of ≈ 7600 stars across 30 open clusters/associations spanning ages of 1.5 Myr to 4 Gyr. We have also developed ChronoFlow : a flexible data-driven model that accurately captures observed rotational dispersion. We show that ChronoFlow can be used to accurately forward-model rotational evolution, and to infer both cluster and individual stellar ages. We recover cluster ages with a statistical uncertainty of 0.06 dex (≈15%), and individual stellar ages with a statistical uncertainty of 0.7 dex. Additionally, we conducted robust systematic tests to analyze the impact of extinction models, cluster membership, and calibration ages. These contribute an additional 0.06 dex of uncertainty in cluster age estimates, resulting in a total error budget of 0.08 dex. We apply ChronoFlow to estimate ages for M34, NGC 2516, NGC 6709, and the Theia 456 stellar stream. Our results show that ChronoFlow can precisely estimate the ages of coeval stellar populations, and constrain ages for individual stars. Furthermore, its predictions may be used to inform physical spin-down models. ChronoFlow is publicly available online ( https://github.com/philvanlane/chronoflow ).}, archive = {J_ApJ}, author = {Phil R. Van-Lane and Joshua S. Speagle and Gwendolyn M. Eadie and Stephanie T. Douglas and Phillip A. Cargile and Catherine Zucker and Yuxi (Lucy) Lu and Ruth Angus}, doi = {10.3847/1538-4357/adcd73}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {59}, shortjournal = {The Astrophys. J.}, title = {ChronoFlow: A data-driven model for gyrochronology}, volume = {986}, year = {2025}, }
• (2025). The origin of the cluster of local interstellar clouds. ApJ, 986(1), 58. (www)

  @article{ , abstract = {The interstellar medium within ≈15 pc of the Sun consists of a complex of 15 diffuse, partially ionized clouds. Located within the Local Bubble, these clouds, known as the Cluster of Local Interstellar Clouds (CLIC), constitute the interstellar environment impinging upon our heliosphere. While each individual cloud can be modeled with a distinct velocity vector, the complex demonstrates a coherent bulk motion suggestive of a common origin. Here, we examine two theories for the origin of the CLIC: that it formed due to an ionization front associated with nearby Strömgren spheres and/or due to a nearby supernova explosion that occurred within the pre-evacuated cavity of the Local Bubble. Tracing back the trajectory of the clouds, we disfavor a purely Strömgren sphere origin, given the CLIC's position interior to the surface of the most significant nearby Strömgren sphere and its motion transverse to the sphere's trajectory. Turning to a supernova origin, we model the formation of the CLIC assuming individual clouds have been swept up over time due to the expansion of a supernova remnant in its pressure-driven snowplow phase. We find that the 3D spatial-dynamical properties of the CLIC can be explained by the most recent supernova that exploded in the nearby Upper Centaurus Lupus cluster ≈1.2 Myr ago and propagated into an ambient density of n ≈ 0.04 cm −3 . Our model predicts that the formation of the individual CLIC clouds occurred progressively over the past 1 Myr and offers a natural explanation for the observed distribution, column density, temperature, and magnetic field structure of the complex.}, archive = {J_ApJ}, author = {Catherine Zucker and Seth Redfield and Sara Starecheski and Ralf Konietzka and Jeffrey L. Linsky}, doi = {10.3847/1538-4357/adc920}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {58}, shortjournal = {The Astrophys. J.}, title = {The origin of the cluster of local interstellar clouds}, volume = {986}, year = {2025}, }
• (2025). Quasi-thermal photosphere emission from structured jets of gamma-ray bursts. ApJ, 986(1), 57. (www)

  @article{ , abstract = {The prompt emission of gamma-ray bursts (GRBs) is supposed to be released from the relativistic jet launched from the central engine. Apart from the nonthermal nature of spectra in the majority of GRBs, there is evidence for the presence of quasi-thermal components in the prompt emission of a few GRBs according to observations by the Fermi satellite. On the other hand, the GRB jet has been revealed as structured in recent research. The theoretical spectra of photosphere emissions observed by an off-axis observer and the dependence of the spectra on the viewing angle under the assumption of structured jets remain unexplored. In this paper, we numerically calculate the instantaneous photosphere spectra by different viewing angles from a structured jet, from which relevant temporal and spectral characteristics are derived. Moreover, we address the necessity of proper treatment of the outflow boundary in the photosphere emission scenario. Furthermore, our calculations suggest that the Einstein Probe and Space-based Multi-band Astronomical Variable Object Monitor will have the capability to detect short GRBs similar to GRB 170817A up to a luminosity distance of 200 Mpc if the off-axis viewing angle is less than 10°.}, archive = {J_ApJ}, author = {Ding-Fang Hu and Jin-Jun Geng and Hao-Xuan Gao and Jing-Zhi Yan and Xue-Feng Wu}, doi = {10.3847/1538-4357/adcf20}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {57}, shortjournal = {The Astrophys. J.}, title = {Quasi-thermal photosphere emission from structured jets of gamma-ray bursts}, volume = {986}, year = {2025}, }
• (2025). Spatial scales of electron density fluctuations in the martian ionosphere. ApJ, 986(1), 56. (www)

  @article{ , abstract = {In recent Martian ionospheric studies, the spatial scales of electron density irregularities have been computed using magnetic field measurements by treating these fluctuations as electromagnetic. As Mars lacks an intrinsic magnetic field, estimation of spatial scales in the parallel and perpendicular directions of the ambient magnetic field is not straightforward. In the present study, the magnetic field averaged over a longer time window is used to get the direction of the ambient magnetic field. The process of averaging removes the short-time fluctuations and retains only the slowly varying part, which can be treated as an ambient magnetic field. This approach is applied to long-term (2014–2023) magnetic field measurements from the fluxgate magnetometer on board the Mars Atmosphere and Volatile EvolutioN (or MAVEN) spacecraft to investigate separately the dominant spatial scales in the parallel and perpendicular directions. The spatial scales parallel and perpendicular to the ambient magnetic field dominantly lie in the range of λ ∣∣ = 150–350 km and λ ⊥ = 50–80 km, respectively. However, the tendency of λ ∣∣ > λ ⊥ weakens in the region of the strong crustal magnetic field. Irregularities with density fluctuations of more than 25% are prevalent in the dawn and dusk sectors at an altitude of 140–180 km. Spatial scales of λ ⊥ < 70 km are more probable at an altitude above 200 km in the Martian ionosphere. Information about the spatial scales of electron density fluctuations is crucial for understanding their impact on the radio wave propagation in the Martian ionosphere, as well as the underlying processes responsible for their generation.}, archive = {J_ApJ}, author = {Chougule Prathmesh and Bharati Kakad and Amar Kakad}, doi = {10.3847/1538-4357/add332}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {56}, shortjournal = {The Astrophys. J.}, title = {Spatial scales of electron density fluctuations in the martian ionosphere}, volume = {986}, year = {2025}, }
• (2025). Thermally induced electromagnetic fluctuations by protons and alpha particles in the solar wind. ApJ, 986(1), 55. (www)

  @article{ , abstract = {We present an initial study on the contribution of alpha particles, alongside electrons and protons, to the generation of thermally induced electromagnetic fluctuations (TIEFs) in space plasmas, such as the solar wind. The inclusion of alpha particles is anticipated to influence the regulation of the quasi-stable region in the beta-anisotropy diagram for both ion species, as well as the amplitude of the fluctuations. For this analysis, we filtered 30 yr of solar wind data at 1 au, focusing on conditions close to isotropy for protons and alpha particles, given that the observational distribution peaks near this state. The filtered data are displayed and organized in the ( β ∥ p , β ∥ α ) plane, where β ∥ denotes the ratio of parallel plasma pressure to magnetic pressure for protons ( p ) and alpha particles ( α ). In this plane, we analyze the ratio of alpha particle to proton density, n α / n p , the squared perpendicular magnetic fluctuations, and compressibility. Furthermore, we compare these magnetic fluctuations with the total fluctuating magnetic energy density derived from a generalized fluctuation–dissipation theorem, highlighting a clear similarity. We also present Fourier spectra for a subset of the data and the corresponding theoretical curve predicted by TIEFs. This study suggests that TIEFs may play a significant role in explaining the unexpected fluctuations observed in space plasmas. Additionally, it provides preliminary evidence that the inclusion of additional ion species could serve as a quantitative test for the theoretical models proposed to describe these fluctuations.}, archive = {J_ApJ}, author = {Rafael O. Medina and Benjamin Toledo and Roberto E. Navarro and Juan A. Valdivia}, doi = {10.3847/1538-4357/add3fa}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {55}, shortjournal = {The Astrophys. J.}, title = {Thermally induced electromagnetic fluctuations by protons and alpha particles in the solar wind}, volume = {986}, year = {2025}, }
• (2025). The tip of red giant branch distances to nearby dwarf galaxies WLM and sextans a with JWST. ApJ, 986(1), 54. (www)

  @article{ , abstract = {Distance measurements to extragalactic systems that are both accurate and precise are cornerstones of modern astrophysics, underpinning the calibration of standard candles and the determination of the Hubble constant. Dwarf galaxies, such as Wolf–Lundmark–Melotte (WLM) and Sextans A, provide valuable laboratories for testing distance scales across different stellar populations. In this work, we utilize the high sensitivity and spatial resolution of the James Webb Space Telescope to measure the distances to WLM and Sextans A using the tip of the red giant branch (TRGB) method. Adopting the TRGB absolute magnitude calibrated by NGC 4258, we determine distance moduli of μ 0,WLM = 24.977 ± 0.018(stat) ± 0.056(sys) mag for WLM and μ 0,SexA = 25.740 ± 0.011(stat) ± 0.057(sys) mag for Sextans A. Our results are consistent within a 3% distance uncertainty with previous measurements based on TRGB, Cepheids, and J-Region Asymptotic Giant Branch methods. With improved distance measurements in the future, these two galaxies have the potential to serve as additional anchor points for TRGB calibration and reduce the TRGB-based distance uncertainty to below 2%.}, archive = {J_ApJ}, author = {Ziming Yan and Shu Wang and Xiaodian Chen and Licai Deng}, doi = {10.3847/1538-4357/add52e}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {54}, shortjournal = {The Astrophys. J.}, title = {The tip of red giant branch distances to nearby dwarf galaxies WLM and sextans a with JWST}, volume = {986}, year = {2025}, }
• (2025). A 7 day multiwavelength flare campaign on AU mic. II. electron densities and kinetic energies from high-frequency radio flares. ApJ, 986(1), 53. (www)

  @article{ , abstract = {M dwarfs are the most common type of star in the solar neighborhood, and many exhibit frequent and highly energetic flares. To better understand these events across the electromagnetic spectrum, a campaign observed AU Mic (dM1e) over 7 days from the X-ray to radio regimes. Here, we present high-time-resolution light curves from the Karl G. Jansky Very Large Array (VLA) Ku band (12–18 GHz) and the Australia Telescope Compact Array (ATCA) K band (16–25 GHz), which observe gyrosynchrotron radiation and directly probe the action of accelerated electrons within flaring loops. Observations reveal 16 VLA and three ATCA flares of varying shapes and sizes, from a short (30 s) spiky burst to a long-duration (∼5 hr) decaying exponential. The Ku -band spectral index is found to often evolve during flares. Both rising and falling spectra are observed in the Ku band, indicating optically thick and thin flares, respectively. Estimations from optically thick radiation indicate higher loop-top magnetic field strengths (∼1 kG) and sustained electron densities (∼10 6 cm −3 ) than previous observations of large M dwarf flares. We estimate the total kinetic energies of gyrating electrons in optically thin flares to be between 10 32 and 10 34 erg when the local magnetic field strength is between 500 and 700 G. These energies are able to explain the combined radiated energies from multiwavelength observations. Overall, values are more aligned with modern radiative-hydrodynamic simulations of M dwarf flares, and future modeling efforts will better constrain findings.}, archive = {J_ApJ}, author = {Isaiah I. Tristan and Rachel A. Osten and Yuta Notsu and Adam F. Kowalski and Alexander Brown and Graeme L. White and Carol A. Grady and Todd J. Henry and Eliot Halley Vrijmoet}, doi = {10.3847/1538-4357/adc565}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {53}, shortjournal = {The Astrophys. J.}, title = {A 7 day multiwavelength flare campaign on AU mic. II. electron densities and kinetic energies from high-frequency radio flares}, volume = {986}, year = {2025}, }
• (2025). Increased lyα opacity in white dwarf photospheres from transient h− resonances. ApJ, 986(1), 52. (www)

  @article{ , abstract = {The structure and emergent flux of hydrogen atmosphere white dwarfs depend on the opacity of the Ly α and Ly β spectral lines. The opacity here is set by the strength and broadening of these lines; the latter is dictated by the far line wing, which is in the "quasi-static" limit of electron broadening, placing it in the incomplete collision regime, and describes the transient parts of electron and ion collisions. These transient stages of the collision form resonances: In the case of ions, they manifest as molecular resonances, while for electrons they are H − resonances, both of which can only be captured quantum-mechanically. Quantum-mechanical calculations have historically preserved only a handful of broadening terms that are most important near the center of the line. However, in the wings of the line, the previously neglected terms that describe the transient stages of the collision need to be included. This requirement arises because, in the line wings, the broadening from the 1 s ground state, which is generally assumed to be extremely small compared to the broadening of the upper state, is no longer negligible within a quantum-mechanical model that takes into account exchange interactions. The inclusion of all the transient terms results in asymmetries and extra broadening. The increased broadening of Ly α increases the opacity at the energy where most of the flux leaves the star. The broader Ly α lines also impact the visible flux, raising it by an amount that exceeds previously estimated errors.}, archive = {J_ApJ}, author = {Thomas A. Gomez and Mark C. Zammit and Jackson R. White and Evgeny Stambulchik and Ivan Hubeny and Igor Bray and Christopher J. Fontes and Michael H. Montgomery and Bart H. Dunlap and Donald E. Winget}, doi = {10.3847/1538-4357/adc9ae}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {52}, shortjournal = {The Astrophys. J.}, title = {Increased lyα opacity in white dwarf photospheres from transient h− resonances}, volume = {986}, year = {2025}, }
• (2025). Dust continuum radiation maps from MHD simulations of accretion-ejection systems around single and binary stars. ApJ, 986(1), 51. (www)

  @article{ , abstract = {We study the launching of magnetized jets from a resistive circumstellar disk within a binary system, employing a unique combination of 3D MHD jet launching simulations (PLUTO code) and post-processed 3D radiative transfer modeling (RADMC-3D code). Our findings reveal a well-defined jet originating from the inner region of the disk, extending to a larger disk area. While the model attains steady states for a single star, a binary system leads to the emergence of tidal effects such as the formation of "spiral arms" in the disk and inside the jet. Here, we have consistently implemented a time-dependent Roche potential for the gravity of the binary. As a major step forward, we further present the first 3D radiation maps of the dust continuum for the disk-jet structure. In principle, this allows us to compare MHD simulation results to observed disk-outflow features. We, therefore, present convolved images of the dust continuum emission, employing exemplary point spread functions of the MIRI instrument (5 μ m band) and the Atacama Large Millimeter/submillimeter Array (320 μ m band). In these bands, we identify distinguishable features of the disk-jet structure, such as "spiral arms," which we have also seen in the MHD dynamics. For gas density increased by an order of magnitude, the disk becomes optically thick at 5 μ m, but remains bright at 320 μ m. At this wavelength, 320 μ m, enhanced structural features in the disk and the base of the wind become more pronounced and are well resolved in the convolved image.}, archive = {J_ApJ}, author = {Somayeh Sheikhnezami and Christian Fendt and Sareh Ataiee}, doi = {10.3847/1538-4357/adccbf}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {51}, shortjournal = {The Astrophys. J.}, title = {Dust continuum radiation maps from MHD simulations of accretion-ejection systems around single and binary stars}, volume = {986}, year = {2025}, }
• (2025). IGR j12580+0134: The nearest tidal disruption event and its faint resurrection. ApJ, 986(1), 50. (www)

  @article{ , abstract = {Tidal disruption events (TDEs) are X-ray and gamma-ray radiations emerging from the tidal disintegration of a star or substellar object that passes too close to a supermassive black hole (SMBH) at the center of a galaxy. In 2010 November, a TDE designated as IGR J12580+0134 occurred in the galaxy NGC 4845, and it was traced by follow-up XMM-Newton observations in 2011 January. To identify a further TDE based on the radio outburst cycle, we requested NICER monitoring observations for nearly 1 yr beginning in 2023 March, which we studied here along with the previous XMM-Newton observations. We analyzed X-ray brightness changes using hardness analysis and principal component analysis (PCA) and conducted spectral analysis of the source continuum. The NICER observations revealed the presence of some X-ray flares during 2023 March–June that were much fainter than the TDE observed using XMM-Newton in 2011. The PCA component that mainly contributes to the X-ray outbursts during the TDE is a heavily absorbed power-law continuum emission, whereas there is a small contribution from collisionally ionized plasma in the soft excess, likely from a colliding wind or jet. Similarly, the PCA of the NICER data relates the X-ray flares to a power-law spectrum, albeit with a much lower absorbing column, and partially to soft collisional plasma. The faint X-ray flares captured by NICER could be associated with extremely weak accretion onto the SMBH resident in this galaxy and thus potentially a low-luminosity active galactic nucleus.}, archive = {J_ApJ}, author = {A. Danehkar}, doi = {10.3847/1538-4357/adce7e}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {50}, shortjournal = {The Astrophys. J.}, title = {IGR j12580+0134: The nearest tidal disruption event and its faint resurrection}, volume = {986}, year = {2025}, }
• (2025). Constraining the mass of a hypothetical secondary black hole in m87 with the NANOGrav 15 yr data set. ApJ, 986(1), 49. (www)

  @article{ , abstract = {Galaxy mergers, each hosting a supermassive black hole (SMBH), are thought to form SMBH binaries. Motivated by recent observations from the East Asian Very Long Baseline Interferometry (VLBI) Network (EAVN) showing periodic behavior in the M87 jet, a precession of about 11 yr and a transverse oscillation of about 0.9 yr, we constrain the mass of a hypothetical secondary black hole orbiting the primary SMBH in M87. To constrain the mass ratio between the primary SMBH ( M 1 ) and the secondary black hole ( M 2 ) defined as q ≡ M 2 / M 1 ≤ 1, and the length of the semimajor axis of the binary system ( a ), we impose the following three constraints: (i) the lower limit of a , below which the SMBH binary is expected to merge; (ii) the strain amplitude of the gravitational-wave background at nanohertz frequencies shown in the NANOGrav 15 yr data set; and (iii) a finite length of the semimajor axis of M 1 , which can induce periodic behavior in the jet. By combining these constraints, we obtain the allowed parameter space for q and a . If either of the EAVN-detected periods ( T ) corresponds to the binary's orbital period, the allowed range of q is 6.9 × 10 −3 ≤ q ≤ 4.2 × 10 −2 for T ≈ 11 yr, and 3.7 × 10 −2 ≤ q ≤ 1 for T ≈ 0.9 yr. VLBI astrometric monitoring of the jet base of M87 is essential to explore the allowed parameter space for q and a .}, archive = {J_ApJ}, author = {Motoki Kino and Masahiro Nagashima and Hyunwook Ro and Yuzhu Cui and Kazuhiro Hada and Jongho Park}, doi = {10.3847/1538-4357/adceb6}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {49}, shortjournal = {The Astrophys. J.}, title = {Constraining the mass of a hypothetical secondary black hole in m87 with the NANOGrav 15 yr data set}, volume = {986}, year = {2025}, }
• (2025). Unveiling physical conditions and star formation processes in the g47 filamentary cloud. ApJ, 986(1), 48. (www)

  @article{ , abstract = {We present a multiwavelength study of the filamentary cloud G47 ( d ∼ 4.44 kpc), which hosts the mid-infrared bubbles N98, B1, and B2. The SMGPS 1.3 GHz continuum map detects ionized emission toward all the bubbles, marking the first detection of ionized emission toward the B2 bubble. Analysis of the unWISE 12.0 μ m image, the Spitzer 8.0 μ m image, and the Herschel column density and temperature maps reveals two previously unreported hub–filament system candidates associated with the H ii regions B2 and N98, which are powered by massive OB stars. This indirectly favors the applicability of a global nonisotropic collapse scenario for massive star formation in N98 and B2. The position–position–velocity diagram of FUGIN 13 CO (1–0) shows significant velocity variations from 61 to 53 km s −1 toward areas between B2 and N98, where the magnetic field morphology exhibits significant curvature and high velocity dispersion (i.e., 2.3–3.1 km s −1 ) is observed. This may be explained by the expansion of the H ii regions B2 and N98. The energy budget of the cloud, estimated using SOFIA/HAWC+ and molecular line data, suggests that the magnetic field dominates over turbulence and gravity in G47. Furthermore, the radial column density and velocity profiles of G47 display signatures of converging flows in a sheet-like structure. The relative orientations between the magnetic field and local gravity suggest that G47 may undergo gravitational contraction along the magnetic field lines once it becomes magnetically supercritical.}, archive = {J_ApJ}, author = {O. R. Jadhav and L. K. Dewangan and A. Haj Ismail and N. K. Bhadari and A. K. Maity and Ram Kesh Yadav and Moustafa Salouci and Patricio Sanhueza and Saurabh Sharma}, doi = {10.3847/1538-4357/adcee4}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {48}, shortjournal = {The Astrophys. J.}, title = {Unveiling physical conditions and star formation processes in the g47 filamentary cloud}, volume = {986}, year = {2025}, }
• (2025). Recurrent eruptions from the emergence of a toroidal flux tube. ApJ, 986(1), 47. (www)

  @article{ , abstract = {Solar eruptive behavior is often modeled with magnetohydrodynamic simulations of magnetic flux emergence. The usual geometry considered is that of a horizontal cylindrical magnetic flux tube. An alternative is the toroidal tube geometry, which has some advantages over the cylindrical one, namely, that the emerging bipolar pair of sunspots does not drift apart indefinitely. In addition to the toroidal tube, we include an oblique, ambient field in the simulation, which leads to the production of increased activity from the interaction of ambient and emerging fields. Letting the simulation run for a long time reveals that six eruptive jets take place after an initial reconnection jet. In an attempt to better understand the eruptive activity, we examine the evolution of free energy and relative helicity of the coronal volume, as well as the magnetic tension forces acting on the magnetic system. We find that all quantities decrease in magnitude during the eruptive jets and rebuild afterwards. This recurrent activity continues even after flux emergence ceases and stops once the examined quantities saturate to nearly constant values.}, archive = {J_ApJ}, author = {J. Zhuleku and V. Archontis and K. Moraitis}, doi = {10.3847/1538-4357/adda41}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {47}, shortjournal = {The Astrophys. J.}, title = {Recurrent eruptions from the emergence of a toroidal flux tube}, volume = {986}, year = {2025}, }
• (2025). FAST reveals the extended h i halo and accretion signatures of NGC 2683. ApJ, 986(1), 46. (www)

  @article{ , abstract = {We present the results of our recent H i observations conducted on the edge-on galaxy NGC 2683 using the Five-hundred-meter Aperture Spherical radio Telescope (FAST). In comparison to previous observations made by the Very Large Array (VLA), FAST has detected a more extensive distribution of H i . Particularly noteworthy is that the detections made by FAST extend approximately 4 times farther than those of the VLA in the vertical direction from the galactic plane. The total H i flux measured for NGC 2683 amounts to F H i = 112.1 Jy km s −1 (equivalent to a total H i mass of M H i = 2.32 × 10 9 M ⊙ ), which is slightly higher than that detected by VLA. FAST has also identified three dwarf galaxies in close proximity to NGC 2683, namely KK 69, NGC 2683dw1, and NGC 2683dw3? (hereafter dw3?). dw3? is situated within the extended H i distribution of NGC 2683 in projection and lies near the tail of KK 69 extending toward NGC 2683. These observations suggest that dw3? is likely a result of the accretion process from NGC 2683 to KK 69. Furthermore, FAST has detected three high-velocity clouds, with complex B potentially undergoing accretion with NGC 2683. Based on the model from B. Vollmer et al. and incorporating the H i halo component, we found that the model with the added H i halo aligns more closely with our FAST observations in NGC 2683. The estimated mass of this H i halo is 3 × 10 8 M ⊙ , constituting approximately 13% of the total H i mass of the galaxy. We suggest that the origination of this H i halo is more likely attributed to external gas accretion.}, archive = {J_ApJ}, author = {Qian Jiao and Ming Zhu and Bernd Vollmer and Mei Ai and Haiyang Yu and Qinghua Tan and Cheng Cheng and Yang Gao}, doi = {10.3847/1538-4357/add0ba}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {46}, shortjournal = {The Astrophys. J.}, title = {FAST reveals the extended h i halo and accretion signatures of NGC 2683}, volume = {986}, year = {2025}, }
• (2025). Morphological feature distances among the spectral types of SDSS galaxies. ApJ, 986(1), 45. (www)

  @article{ , abstract = {This study investigates the morphological feature distances among various spectral types of galaxies from the Sloan Digital Sky Survey, including strong and weak active galactic nuclei (AGN), quasi-stellar objects (QSOs), quiescent, and star-forming galaxies. We evaluated the clustering and relative distances of these spectral types in the multidimensional morphological feature space. The results indicate that AGN and QSOs are more closely associated with quiescent galaxies than with star-forming ones, indicating a potential regulation of star formation by AGN activity. Furthermore, the analysis underlines the role of AGN feedback in the dwarf regime having ∼10%–50% closer distances from AGN types to the quiescent type than to the star-forming type in the dwarf regime −18 > M r > −20, compared to <15% closer in the massive regime M r < −21. The continuous probability analysis of spectral types being Hubble types upholds the distance analysis results having a range of the probability distribution of AGN types similar to the quiescent type, especially in dwarf galaxies.}, archive = {J_ApJ}, author = {Duho Kim and Garreth Martin}, doi = {10.3847/1538-4357/add152}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {45}, shortjournal = {The Astrophys. J.}, title = {Morphological feature distances among the spectral types of SDSS galaxies}, volume = {986}, year = {2025}, }
• (2025). Li-rich unevolved stars from LAMOST-MRS. ApJ, 986(1), 44. (www)

  @article{ , abstract = {Based on the spectra from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope medium-resolution spectroscopic survey, we select a sample of 88 Li-rich unevolved star candidates. We redetermine their photospheric lithium abundances, A(Li), through the spectral synthesis method, and take the nonlocal thermodynamic equilibrium (NLTE) into account. It is found that there are 62 stars with A(Li) ranging from 3.33 to 4.59 dex. Among them, 23 stars are young stellar objects. There are 33 super Li-rich unevolved stars with A(Li) higher than 3.8 dex, and 24 of them are newly identified. The NLTE corrections for A(Li) are negative, with a maximum value of around 0.5 dex. Our results suggest that the mechanisms such as mass transfer in binary systems, accretion of circumstellar materials, and diffusion processes may contribute to lithium enrichment in their respective samples.}, archive = {J_ApJ}, author = {Ze-Ming Zhou and Jian-Rong Shi and Shao-Lan Bi and Hong-Liang Yan and Kai-Ke Pan and Ming-Yi Ding and Jiang-Tao Wang and Shuai Liu and Chun-Qian Li and Yu-Tao Zhou and Jing-Hua Zhang and Xiang-Song Fang and Xian-Fei Zhang and Tian-Yi Chen and Xiao-Jin Xie and Yao-Jia Tang and Tai-Sheng Yan and Guo Li}, doi = {10.3847/1538-4357/add2fe}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {44}, shortjournal = {The Astrophys. J.}, title = {Li-rich unevolved stars from LAMOST-MRS}, volume = {986}, year = {2025}, }
• (2025). Electrostatic field formed by charge separation in antiparallel magnetic reconnection. ApJ, 986(1), 43. (www)

  @article{ , abstract = {The Hall effect resulting from the decoupled motions between ions and electrons is a critical factor in modeling collisionless magnetic reconnection. It leads to the production of charge separation in the reconnection plane, generating the electrostatic field with components perpendicular and parallel to the magnetic field. In this paper, using a 2.5-dimensional particle-in-cell simulation, we investigate the formation of the charge separation in antiparallel magnetic reconnection. The charge separation is formed in three regions: the electron inflow region and the dipolarization front (DF) region both exhibit a positive charge density, while the electron outflow region exhibits a negative charge density. These charge separations generate the Hall electric field perpendicular to the magnetic field and the parallel electrostatic field. We quantitatively analyze the effects of the magnetic flux tube's geometric dimensions and the parallel electron flux on the formation of charge separation. In the electron inflow region, the parallel electron flux from regions with smaller cross sections to regions with larger cross sections reduces electron density, generating a positive charge density near the separatrix. In contrast, within the outflow region, the parallel electron flux from regions with larger cross sections to regions with smaller cross sections increases electron density, generating a negative charge density near the separatrix. Besides, we attribute the charge separation in the DF region mainly to the acceleration of electrons, which generates a sharply varying parallel electron flux. This drives a net outflow of electrons and establishes an accumulation of positive charge.}, archive = {J_ApJ}, author = {Shihang Hu and Quanming Lu and Yukang Shu and San Lu and Kai Huang and Jia Nan}, doi = {10.3847/1538-4357/add694}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {43}, shortjournal = {The Astrophys. J.}, title = {Electrostatic field formed by charge separation in antiparallel magnetic reconnection}, volume = {986}, year = {2025}, }
• (2025). The roman view of strong gravitational lenses. ApJ, 986(1), 42. (www)

  @article{ , abstract = {Galaxy–galaxy strong gravitational lenses can constrain dark matter models and the Lambda cold dark matter cosmological paradigm at subgalactic scales. Currently, there is a dearth of images of these rare systems with high signal-to-noise ratio (SNR) and angular resolution. The Nancy Grace Roman Space Telescope (hereafter Roman), scheduled for launch in late 2026, will play a transformative role in strong-lensing science with its planned wide-field surveys. With its remarkable 0.281 square degree field of view and diffraction-limited angular resolution of ~0 \mathop{.}\limits^{\unicode{x02033}} 1, Roman is uniquely suited to characterizing dark matter substructure from a robust population of strong lenses. We present a yield simulation of detectable strong lenses in Roman's planned High Latitude Wide Area Survey (HLWAS). We simulate a population of galaxy–galaxy strong lenses across cosmic time with cold dark matter subhalo populations, select those detectable in the HLWAS, and generate simulated images accounting for realistic Wide Field Instrument detector effects. For a fiducial case of single 146 s exposures, we predict around 160,000 detectable strong lenses in the HLWAS, of which about 500 will have sufficient SNR to be amenable to detailed substructure characterization. We investigate the effect of variation of the point-spread function across Roman's field of view on detecting individual subhalos and the suppression of the subhalo mass function at low masses. Our simulation products are available to support strong-lens science with Roman, such as training neural networks and validating dark matter substructure analysis pipelines.}, archive = {J_ApJ}, author = {Bryce Wedig and Tansu Daylan and Simon Birrer and Francis-Yan Cyr-Racine and Cora Dvorkin and Douglas P. Finkbeiner and Alan Huang and Xiaosheng Huang and Rahul Karthik and Narayan Khadka and Priyamvada Natarajan and Anna M. Nierenberg and Annika H. G. Peter and Justin D. R. Pierel and Xianzhe TZ Tang and Risa H. Wechsler}, doi = {10.3847/1538-4357/adc24f}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {42}, shortjournal = {The Astrophys. J.}, title = {The roman view of strong gravitational lenses}, volume = {986}, year = {2025}, }
• (2025). A persistent disk wind and variable jet outflow in the neutron-star low-mass X-ray binary GX 13+1. ApJ, 986(1), 41. (www)

  @article{ , abstract = {In low-mass X-ray binaries (LMXBs), accretion flows are often associated with either jet outflows or disk winds. Studies of LMXBs with luminosities up to roughly 20% of the Eddington limit indicate that these outflows generally do not co-occur, suggesting that disk winds might inhibit jets. However, previous observations of LMXBs accreting near or above the Eddington limit show that jets and winds can potentially coexist. To investigate this phenomenon, we carried out a comprehensive multiwavelength campaign (using the Very Large Array (VLA), Chandra/High Energy Transmission Grating Spectrometer (HETG), and NICER) on the near-Eddington neutron-star Z-source LMXB GX 13+1. NICER and Chandra/HETG observations tracked GX 13+1 across the entire Z track during high Eddington rates, detecting substantial resonance absorption features originating from the accretion disk wind in all X-ray spectra, which implies a persistent wind presence. Simultaneous VLA observations captured a variable radio jet, with radio emission notably strong during all flaring branch observations—contrary to typical behavior in Z sources—and weaker when the source was on the normal branch. Interestingly, no clear correlation was found between the radio emission and the wind features. Analysis of VLA radio light curves and simultaneous Chandra/HETG spectra demonstrates that an ionized disk wind and jet outflow can indeed coexist in GX 13+1, suggesting that their launching mechanisms are not necessarily linked in this system.}, archive = {J_ApJ}, author = {Daniele Rogantini and Jeroen Homan and Richard M. Plotkin and Maureen van den Berg and James Miller-Jones and Joey Neilsen and Deepto Chakrabarty and Rob P. Fender and Norbert Schulz}, doi = {10.3847/1538-4357/adcabe}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {41}, shortjournal = {The Astrophys. J.}, title = {A persistent disk wind and variable jet outflow in the neutron-star low-mass X-ray binary GX 13+1}, volume = {986}, year = {2025}, }
• (2025). Resonant absorption and fluctuations via hybrid simulations on coronal loops. i. plasma multifluid description. ApJ, 986(1), 40. (www)

  @article{ , abstract = {We investigate the resonant absorption process of a combination of left- and right-hand polarized waves (with a fixed perturbation amplitude) in a plasma slab with linearly inhomogeneous particle densities. Different thicknesses of the layers and angles of the background magnetic field to the plane of the slab, representing the degree of magnetization of the slab, are studied via 2D−3V PIC-hybrid simulations with a fixed perturbation amplitude. We identify the process of resonant absorption of the large-scale mode in the inhomogeneous layers and compare the damping rate of the transverse oscillations with single-fluid, linear MHD estimations. By following the spectral densities of the magnetic field fluctuations, it is found that kinetic scales are achieved in most of the simulated cases, particularly in the case of thinner inhomogeneous layers and in cases where the plasma slab is not weakly magnetized. In particular, the scales of the fluctuations can reach the proton inertial length. The small-scale fluctuations are identified as quasi-perpendicular oscillations localized within the inhomogeneous layers, and their properties in the spectral representation agree with theoretical properties of kinetic Alfvén waves predicted by kinetic and Hall-MHD theories.}, archive = {J_ApJ}, author = {Hugo A. Carril and Jaume Terradas and Roberto E. Navarro and Adolfo F. Viñas and Marcel Goossens}, doi = {10.3847/1538-4357/adceac}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {40}, shortjournal = {The Astrophys. J.}, title = {Resonant absorption and fluctuations via hybrid simulations on coronal loops. i. plasma multifluid description}, volume = {986}, year = {2025}, }
• (2025). Red supergiant problem viewed from the nebular phase spectroscopy of type II supernovae. ApJ, 986(1), 39. (www)

  @article{ , abstract = {The red supergiant (RSG) problem refers to the observed dearth of luminous RSGs identified as progenitors of Type II supernovae (SNe II) in pre-SN imaging. Understanding this phenomenon is essential for studying pre-SN mass loss and the explodability of core-collapse SNe. In this work, we reassess the RSG problem using late-phase spectroscopy of a sample of 50 SNe II. The [O I ] λλ 6300,6363 emission in the spectra is employed to infer the zero-age main-sequence (ZAMS) mass distribution of the progenitors, which is then transformed into a luminosity distribution via an observation-calibrated mass–luminosity relation. The resulting luminosity distribution reveals an upper cutoff at {\mathrm{log}}\,L/{L}_{\odot }\,=\,5.2{1}_{-0.07}^{+0.09}\, dex, and the RSG problem is statistically significant at the 2 σ –3 σ level. Assuming single RSG progenitors that follow the mass–luminosity relation of KEPLER models, this luminosity cutoff corresponds to an upper ZAMS mass limit of 20.6{3}_{-1.64}^{+2.42}\,{M}_{\odot } . Comparisons with independent measurements, including pre-SN imaging and plateau-phase light curve modeling, consistently yield an upper ZAMS mass limit below ∼25 M ⊙ , with a significance level of 1 σ –3 σ . While each individual method provides only marginal significance, the consistency across multiple methodologies suggests that the lack of luminous RSG progenitors may reflect a genuine physical problem. Finally, we discuss several scenarios to account for this issue should it be confirmed as a true manifestation of stellar physics.}, archive = {J_ApJ}, author = {Qiliang Fang and Takashi J. Moriya and Keiichi Maeda}, doi = {10.3847/1538-4357/adceae}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {39}, shortjournal = {The Astrophys. J.}, title = {Red supergiant problem viewed from the nebular phase spectroscopy of type II supernovae}, volume = {986}, year = {2025}, }
• (2025). Mapping the star formation and h i gas properties of galaxies along large-scale structures around the virgo cluster. ApJ, 986(1), 38. (www)

  @article{ , abstract = {We investigate the star formation and neutral atomic hydrogen (H i ) gas properties of galaxies along three large-scale filaments and two galaxy groups in the wide field around the Virgo cluster. Our goal is to understand how galaxies are processed in low-density environments before falling into high-density regions. Combining the spatial distribution of galaxies with multiwavelength colors such as W3 − ​​​​​W1, NUV − r , and g − r , we find a predominance of blue galaxies across the structures, indicating normal-to-enhanced star formation, similar to that of isolated galaxies. However, one filament and one group show a significant number of red galaxies (32% and 20%, respectively), suggesting that star formation has been suppressed in low-density environments before reaching high-density regions. Intriguingly, these red galaxies span a wide range of stellar masses, and the presence of red dwarfs support that not only mass but also environment plays an important role in the quenching of star formation in cluster outskirts. One particular filament, potentially connected to Virgo, already has a group of red populations outside Virgo's R 200 , making these galaxies good candidates for being " preprocessed " before entering the Virgo cluster. In addition, several galaxies in the filaments and groups possess relatively low H i gas contents, similar to cluster galaxies. However, the overall fraction of H i -deficient galaxies is not as significantly high as the fraction of red galaxies in these structures. This suggests that H i gas properties are less influenced by the environment than star formation properties in low-density regions, possibly due to gas replenishment through accretion.}, archive = {J_ApJ}, author = {Hyein Yoon and O. Ivy Wong and Aeree Chung and Shan Huang}, doi = {10.3847/1538-4357/adceaf}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {38}, shortjournal = {The Astrophys. J.}, title = {Mapping the star formation and h i gas properties of galaxies along large-scale structures around the virgo cluster}, volume = {986}, year = {2025}, }
• (2025). Initiation route of coronal mass ejections. II. the role of filament mass. ApJ, 986(1), 37. (www)

  @article{ , abstract = {A thorough understanding of the initiation of coronal mass ejections (CMEs), which is manifested as a slow rise of pre-eruptive structures before the impulsive ejection in kinematics, is key for forecasting solar eruptions. In our previous work, we showed that the slow rise of a hot flux rope with coronal mass density is caused by the moderate magnetic reconnection occurring in the hyperbolic flux tube (HFT) combined with the torus instability. However, it remains unclear how the initiation process varies when a filament is present in the pre-eruptive flux rope. In this work, we reveal the complete initiation route of a CME containing filament mass with a state-of-the-art full-magnetohydrodynamics simulation. The comprehensive analyses show that the filament mass has an important impact on the CME initiation through triggering and driving the slow rise of flux rope with its drainage, besides the contributions of HFT reconnection and torus instability. Finally, in combination with our previous work, we propose that the enhanced drainage of filament mass and various features related to the HFT reconnection, such as the split of pre-eruptive structure and the preflare loops and X-ray emissions, can serve as precursors of CME initiation in observations.}, archive = {J_ApJ}, author = {Chen Xing and Xin Cheng and Guillaume Aulanier and Mingde Ding}, doi = {10.3847/1538-4357/adceb5}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {37}, shortjournal = {The Astrophys. J.}, title = {Initiation route of coronal mass ejections. II. the role of filament mass}, volume = {986}, year = {2025}, }
• (2025). HOLESOM: Constraining the properties of slowly accreting massive black holes with self-organizing maps. ApJ, 986(1), 36. (www)

  @article{ , abstract = {Accreting massive black holes (MBHs, with M • > 10 3 M ⊙ ) are known for their panchromatic emission, spanning from radio to gamma rays. While MBHs accreting at significant fractions of their Eddington rate are readily detectable, those accreting at much lower rates in radiatively inefficient modes often go unnoticed, blending in with other astrophysical sources. This challenge is particularly relevant for gas-starved MBHs in external galaxies and those possibly wandering in the Milky Way. We present HOLESOM (HOLESOM is publicly available at: https://github.com/valentinalatorre/holesom ), a machine learning-powered tool based on the self-organizing maps (SOMs) algorithm, specifically designed to identify slowly accreting MBHs using sparse photometric data. Trained on a comprehensive set of ∼20,000 spectral energy distributions, HOLESOM can (i) determine if the photometry of a source is consistent with slowly accreting MBHs and (ii) estimate its black hole mass and Eddington ratio, including uncertainties. We validate HOLESOM through extensive tests on synthetic data and real-world cases, including Sagittarius A ⋆ (Sgr A ⋆ ), demonstrating its effectiveness in identifying slowly accreting MBHs. Additionally, we derive analytical relations between radio and X-ray luminosities to further constrain physical parameters. The primary strength of HOLESOM lies in its ability to accurately identify MBH candidates, which can then be targeted for follow-up photometric and spectroscopic observations. Fast and scalable, HOLESOM offers a robust framework for automatically scanning large multiwavelength data sets, making it a valuable tool for unveiling hidden MBH populations in the local Universe.}, archive = {J_ApJ}, author = {Valentina La Torre and Fabio Pacucci}, doi = {10.3847/1538-4357/adced9}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {36}, shortjournal = {The Astrophys. J.}, title = {HOLESOM: Constraining the properties of slowly accreting massive black holes with self-organizing maps}, volume = {986}, year = {2025}, }
• (2025). Nonstandard thermal history and formation of primordial black holes and SIGWs in Einstein–Gauss–Bonnet gravity. ApJ, 986(1), 35. (www)

  @article{ , abstract = {In this article, we examine the formation of primordial black holes (PBHs) in the mutated hilltop inflation model coupled with the Einstein–Gauss–Bonnet term. A suitable choice of the coupling function can produce the ultra-slow-roll (USR) regime during the inflationary phase, which lasts for some number of e-folds leading to a significant enhancement to the curvature power spectrum for small scales so that it grows up to the order of { \mathcal O }(1{0}^{-2}) ; a crucial feature for producing PBH and scalar-induced gravitational waves (SIGWs). We investigate the formation of PBHs for different sets of parameters. The presented model is capable of producing PBH in a wide range of mass, from { \mathcal O }(1{0}^{-14}){M}_{\odot } to { \mathcal O }(10){M}_{\odot } . PBHs with mass { \mathcal O }(1{0}^{-5}){M}_{\odot } can account for the microlensing event in Optical Gravitational Lensing Experiment as well as the asteroid masses { \mathcal O }(1{0}^{-15}){M}_{\odot }-{ \mathcal O }(1{0}^{-12}){M}_{\odot } ; PBH can be attributed to 100% of the dark matter present in the Universe. Whereas PBHs in the mass range { \mathcal O }(10){M}_{\odot } are compatible with LIGO-Virgo data. Our investigation is generalized to include the effect of nonstandard thermal history with an equation of state 1/3 < ω ≤ 1 on PBHs, and it is shown that this possibility can severely impact the formation and abundance of PBHs. The enhancement of the scalar power spectrum also leads to the SIGWs. It is realized that, by increasing ω , there is a slight enhancement of the SIGWs. Moreover, produced SIGWs are well within the detectable frequency ranges of current and future detectors.}, archive = {J_ApJ}, author = {Yogesh and Abolhassan Mohammadi}, doi = {10.3847/1538-4357/adcee5}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {35}, shortjournal = {The Astrophys. J.}, title = {Nonstandard thermal history and formation of primordial black holes and SIGWs in Einstein–Gauss–Bonnet gravity}, volume = {986}, year = {2025}, }
• (2025). A sample of extreme eclipsing binaries with accretion disks from LAMOST and ZTF. ApJ, 986(1), 34. (www)

  @article{ , abstract = {Extreme eclipsing binaries may harbor peculiar physical properties. In this work, we aim to identify a sample of such systems by selecting binaries with pronounced eclipsing light curves, characterized by large variability (Δmag > 0.3 in the g band of the Zwicky Transient Facility, ZTF) and significant differences between primary and secondary eclipses (eclipse depth ratio >20 in the ZTF g band). We identified 23 candidates by combining the photometric data and the LAMOST spectroscopic survey. Spectroscopic analysis revealed that all of these systems are dominated by A-type stars in the optical band. Further investigation confirmed that all 23 candidates are Algol-type binaries, with 22 of them being newly discovered. Their orbital periods range from 2.57 to 19.21 days. These systems consist of low-luminosity, highly stripped subgiant donors and accreting A-type stars. The donor stars, with radii of 2.5–8.9 R ⊙ and effective temperatures around 4000 K, have typical masses of M 2 ∼ 0.3 M ⊙ , indicating substantial mass loss through Roche-lobe overflow. The presence of ellipsoidal variability and H α emission provides strong evidence for ongoing mass transfer. By fitting the spectral energy distributions, spectra, and light curves, we found that most of the accretors have luminosities lower than expected from the mass–luminosity relation, aligning with the predicted faint phase for mass-gaining stars. Three objects of our sample exhibit pulsations with periods from 18 minutes to 8 hr, providing opportunities for asteroseismic studies. The low mass transfer rates and stability make the sample excellent systems for studying mass accretion, advancing our understanding of the evolution of Algol-type binaries.}, archive = {J_ApJ}, author = {Jiangxinxin Zhuang and Zhi-Xiang Zhang and Wei-Min Gu and Senyu Qi}, doi = {10.3847/1538-4357/adcf91}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {34}, shortjournal = {The Astrophys. J.}, title = {A sample of extreme eclipsing binaries with accretion disks from LAMOST and ZTF}, volume = {986}, year = {2025}, }
• (2025). Stability and dynamics of three-mode coupling in δ scuti stars. ApJ, 986(1), 33. (www)

  @article{ , abstract = {Recent observations of δ Scuti stars find evidence of nonlinear three-mode coupling in their oscillation spectra. There are two types of three-mode coupling likely to be important in δ Scuti stars: (i) direct coupling, in which two linearly unstable modes (driven by the κ -mechanism) excite a linearly stable mode, and (ii) parametric coupling, in which one linearly unstable mode excites two linearly stable modes. M. Breger & M. H. Montgomery find especially strong evidence of direct coupling in the δ Scuti star KIC 8054146. However, direct coupling is inherently unstable and cannot be the mechanism by which the modes saturate and achieve nonlinear equilibrium. By integrating the amplitude equations of small mode networks, we show that the modes can achieve equilibrium if parametric coupling operates in tandem with direct coupling. Using mode parameters calculated from a δ Scuti model, we also find that parametric and direct coupling are likely to be simultaneously active. Importantly, parametric coupling does not necessarily disrupt the correlations found in KIC 8054146 between the amplitudes and phases of the directly coupled modes. We conclude that δ Scuti stars are likely impacted by both parametric and direct coupling, and that accounting for both in future large-mode-network calculations may help explain the complicated mode dynamics observed in many δ Scuti stars.}, archive = {J_ApJ}, author = {Mohammed Mourabit and Nevin N. Weinberg}, doi = {10.3847/1538-4357/add019}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {33}, shortjournal = {The Astrophys. J.}, title = {Stability and dynamics of three-mode coupling in δ scuti stars}, volume = {986}, year = {2025}, }
• (2025). Polarization evolution of gamma-ray burst prompt emission with bulk acceleration. ApJ, 986(1), 32. (www)

  @article{ , abstract = {During the prompt phase, Poynting-flux-dominated jets undergo acceleration accompanied by magnetic dissipation. By using an outward-propagating thin-shell model, where bulk Lorentz factors Γ increase with radius and the magnetic field strength decay is related to the acceleration and the energy conversion rate, this process can be investigated through time-resolved polarization analysis. Faster acceleration produces a greater flux, steeper light-curve growth followed by a sharper decline, and polarization degree decreases sharply. With a fixed acceleration index, lower energy conversion rates are associated with lower flux, shallower rises and declines in light curves, lower polarization degree, smoother decline for on-beam ( q = θ v / θ j < 1) emission, and sharper decline for off-beam ( q > 1) emission in polarization curves. Both jet acceleration and magnetic dissipation enhance the likelihood of polarization angle flips in observations with small viewing angles, while also leading to higher polarization degrees after the flip in observations with larger viewing angles. The joint analysis of light curves and polarization provides valuable insights into gamma-ray burst motion and energy conversion processes. Rapid decline in the light curve indicates fast acceleration and high energy conversion rates, while gradual light-curve decline coupled with polarization angle flips (for small viewing angles) or the higher polarization degree after flipping (for large viewing angles) suggests acceleration accompanied by magnetic dissipation. Otherwise, the jet is coasting or slowly accelerating at this time.}, archive = {J_ApJ}, author = {Qian Zhong and Hong-Bang Liu and Kangfa Cheng and Zu-Ke Feng and Jiang-Chuan Tuo and Qian-Nan Mai and Jirong Mao and En-Wei Liang}, doi = {10.3847/1538-4357/add0ac}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {32}, shortjournal = {The Astrophys. J.}, title = {Polarization evolution of gamma-ray burst prompt emission with bulk acceleration}, volume = {986}, year = {2025}, }
• (2025). Clumpy starburst in a local dwarf galaxy, NGC 1522. ApJ, 986(1), 31. (www)

  @article{ , abstract = {To investigate the star-forming process in nearby dwarf galaxies, we present integral field unit observations of the star-forming dwarf galaxy NGC 1522 with the Very Large Telescope/Multi Unit Spectroscopic Explorer as a part of the Dwarf Galaxy Integral Survey. Our observations reveal the presence of a star-forming clumpy ring in its central region. We identify nine distinct star-forming clumps based on an extinction-corrected H α emission line map, with a total star formation rate of about 0.1 M ⊙ yr −1 . The nine clumps are considered to be starbursts, which represent an extreme case in the local Universe, without invoking major merging. We investigate the properties of ionized gas using the strong emission lines and "BPT" diagrams, in conjunction with velocity mapping. Our analysis unveils intriguing patterns, including a positive metallicity gradient and low N/O abundance ratio. This peculiar distribution of metallicity may signify external gas accretion. Our results suggest that the ongoing star formation in NGC 1522 might be triggered and sustained by the inflow of external metal-poor gas.}, archive = {J_ApJ}, author = {Liuze Long and Yulong Gao and Qiusheng Gu and Yong Shi and Xin Li and Can Xu and Yifei Jin and Zhiyuan Zheng and Jing Dou and Fuyan Bian and Xiaoling Yu}, doi = {10.3847/1538-4357/add0b7}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {31}, shortjournal = {The Astrophys. J.}, title = {Clumpy starburst in a local dwarf galaxy, NGC 1522}, volume = {986}, year = {2025}, }
• (2025). Binding energies of small interstellar molecules on neutral and charged amorphous solid water surfaces. ApJ, 986(1), 30. (www)

  @article{ , abstract = {The interstellar medium (ISM) is all but empty. To date, more than 300 molecules have already been discovered. Because of the extremely low temperature, the gas-phase chemistry is dominated by barrierless exothermic reactions of radicals and ions. However, several abundant molecules and organic molecules cannot be produced efficiently by gas-phase reactions. To explain the existence of such molecules in the ISM, gas-surface interactions between small molecules and dust particles covered with amorphous solid water (ASW) mantles must be considered. In general, surface processes such as adsorption, diffusion, desorption, and chemical reactions can be linked to the binding energy of molecules to the surface. Hence, a lot of studies have been performed to identify the binding energies of interstellar molecules on ASW surfaces. Cosmic radiation and free electrons may induce a negative charge on the dust particles, and the binding energies may be affected by this charge. In this study, we calculate the binding energies of CO, CH 4 , and NH 3 on neutral and charged ASW surfaces using density functional theory calculations. Our results indicate that CO can interact with the surface charge, increasing its binding energy. In contrast, the binding energy of CH 4 remains unchanged in the presence of surface charge, and that of NH 3 typically decreases.}, archive = {J_ApJ}, author = {Tobe Vorsselmans and Erik C. Neyts}, doi = {10.3847/1538-4357/add145}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {30}, shortjournal = {The Astrophys. J.}, title = {Binding energies of small interstellar molecules on neutral and charged amorphous solid water surfaces}, volume = {986}, year = {2025}, }
• (2025). Dynamically driven evolution of molecular gas in the barred spiral galaxy m83 traced by CO j = 2–1/1–0 line ratio variations. ApJ, 986(1), 29. (www)

  @article{ , abstract = {We show the variations of the CO J = 2–1/1–0 line ratio ( R 21/10 ) across the barred spiral galaxy M83, using the 46 pc resolution data from the Atacama Large Millimeter/submillimeter Array. The R 21/10 map clearly evidences the systematic large-scale variations as a function of galactic structures. Azimuthally, it starts from low R 21/10 ≲ 0.7 in the interarm regions and becomes high ≳0.7 in the bar and spiral arms, suggesting that the density and/or kinetic temperature of molecular gas increase by about a factor of 2–3. This evolution is seen even in the parts of spiral arms without star formation, and R 21/10 is often elevated even higher to ∼0.8–1.0 when H ii regions exist in the vicinity. Radially, R 21/10 starts very high ≳1.0 at the galactic center, remains low ≲0.7 in the bar region, increases to ≳0.7 around the bar end, and again decreases to ≲0.7 in the rest of disk where the spiral arms dominate. The evolutionary sequence is synchronized with galactic rotation, and therefore, it is determined largely by the galactic structures and dynamics and is governed by the galactic rotation timescales. The R 21/10 map also shows that the influence of stellar feedback is localized and limited. Massive, large, and non-star-forming molecular structures have low R 21/10 , which also suggests that the bulk molecular gas in the disk is not regulated by stellar feedback, but more likely by galactic structures and dynamics. These results are consistent with suggestions by the earlier studies of the Milky Way and other barred spiral galaxies, and thus, are likely general among barred spiral galaxies in the local Universe.}, archive = {J_ApJ}, author = {Jin Koda and Fumi Egusa and Akihiko Hirota and Amanda M Lee and Tsuyoshi Sawada and Fumiya Maeda}, doi = {10.3847/1538-4357/add1dc}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {29}, shortjournal = {The Astrophys. J.}, title = {Dynamically driven evolution of molecular gas in the barred spiral galaxy m83 traced by CO j = 2–1/1–0 line ratio variations}, volume = {986}, year = {2025}, }
• (2025). Event rate density and luminosity function of newborn-magnetar-driven X-ray transients from neutron star binary mergers. ApJ, 986(1), 28. (www)

  @article{ , abstract = {X-ray transients (XTs) driven by newborn magnetars from mergers of neutron star binaries (NSBs) have occasionally been detected in the narrow-field Chandra Deep Field-South (CDF-S) survey and the Swift/X-Ray Telescope observations of short gamma-ray bursts. Quantifying their event rate density (ERD) and luminosity function (LF) is critical for understanding NSB coalescence and magnetar formation. Utilizing population synthesis calculations incorporating various equations of state (EoSs), we derive a local ERD of ∼300 Gpc −3 yr −1 and a redshift-dependent ERD profile peaking at z = 1.81 followed by a rapid decline beyond z ∼ 4. Constructing an XT sample based on CDF-S and Swift observations, we characterize the LF by a single power-law function at L ≤ 4.75 × 10 46 erg s −1 with a slope of −1.03, followed by a broken power-law function in which the break luminosity is L b = 4.38 × 10 47 erg s −1 and the slopes are −0.28 and −1.66. Based on the ERD and the LF, we estimate that the Einstein Probe (EP) detection rate is ∼31 yr −1 , adopting a conservative threshold flux of 10 −9 erg s −1 , a luminosity range of L ∈ [2 × 10 44 , 2 × 10 49 ] erg s −1 , and a correction for the jet opening angle of ∼16 ∘ . This detection rate is consistent with the EP observations during its first year of operation. It is important to note that our estimation is subject to uncertainties arising from the LF derivation. Future EP observations of these XT events will be crucial in reducing these uncertainties.}, archive = {J_ApJ}, author = {Le Zou and Ji-Gui Cheng and Rui-Chong Hu and Wen-Jin Xie and En-Wei Liang}, doi = {10.3847/1538-4357/add2f7}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {28}, shortjournal = {The Astrophys. J.}, title = {Event rate density and luminosity function of newborn-magnetar-driven X-ray transients from neutron star binary mergers}, volume = {986}, year = {2025}, }
• (2025). Evidence for a catastrophically disrupted open cluster. ApJ, 986(1), 27. (www)

  @article{ , abstract = {Of the many discoveries uncovered by the Gaia astrometric mission, some of the most exciting are related to nearby dispersed stellar structures. We analyze one such structure in the Milky Way disk, OCSN-49, a coeval stellar stream with 257 identified members spanning approximately 30° across the sky. We obtained high-resolution spectroscopic data for four members that span the stream's extent, finding these four stars to have solar metallicities and remarkably homogeneous chemistry. Through a combination of isochrone fitting, lithium abundance analysis, and gyrochronology, we find a consistent stellar age of 400–600 Myr. Integrating stellar orbits backwards reveals that OCSN-49 converged to a single point at a much younger age. By integrating unbound model stars forward and comparing them to the current phase-space distribution of OCSN-49, we derive a dynamical age of 83 ± 1 Myr, inconsistent with the age of the stellar population. The discrepancy between the kinematic and stellar age indicators is naturally explained by a disruptive event that unbound OCSN-49 roughly 500 Myr into its lifetime. Based on rate estimates, disruption due to a passing giant molecular cloud (GMC) is the most likely culprit. Assuming a single encounter, we find that a nearly head-on collision with a fairly massive GMC (∼10 5 M ⊙ ) was necessary to unbind the cluster, although encounters with multiple GMCs may be responsible. To our knowledge, OCSN-49 serves as the first known remnant of a catastrophically disrupted open cluster, and therefore serves as a benchmark for further investigating cluster disruption in the Milky Way.}, archive = {J_ApJ}, author = {Alexis N. Miller and Kyle R. Tregoning and Jeff J. Andrews and Simon C. Schuler and Jason L. Curtis and Marcel A. Agüeros and Phillip A. Cargile and Julio Chanamé}, doi = {10.3847/1538-4357/adceb8}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {27}, shortjournal = {The Astrophys. J.}, title = {Evidence for a catastrophically disrupted open cluster}, volume = {986}, year = {2025}, }
• (2025). Multicomponent ionized gas outflows in the hot dust-obscured galaxy w2026+0716 with Keck/OSIRIS. ApJ, 986(1), 26. (www)

  @article{ , abstract = {We present narrowband-filtered integral field unit observations of the hot dust-obscured galaxy (Hot DOG) WISE J202615.27+071624.0 (hereafter W2026+0716) at redshift z = 2.570 using Keck/OSIRIS. Our analysis reveals a multicomponent ionized gas outflow structure in this heavily obscured active galactic nucleus (AGN) host galaxy. Multicomponent Gaussian decomposition of the [O iii ] and H α emission lines uncovers extremely broad and asymmetric profiles, characteristic of AGN-driven outflows. Kinematic mapping shows spatially distinct structures: the [O iii ]- and H α -dominated components (with radii of 1.20 ± 0.56 kpc) are separated by a projected offset of ∼1.1 kpc and exhibit divergent velocity regimes. The [O iii ] outflow reaches a velocity of 3210 ± 50 km s −1 , while the H α outflow component attains 2310±840 km s −1 . Dynamical modeling supports a biconical outflow structure, with [O iii ] and H α emissions dominating separate cones and significant dust obscuration of the redshifted outflow. Their comparable momentum outflow rates and energy outflow rates suggest a potential physical connection in their driving mechanisms. Spectral energy distribution analysis reveals anomalous optical/UV excess, attributed to AGN photon scattering by dust or outflowing material, classifying W2026+0716 as a "Blue Hot DOG". The derived outflow timescale (∼10 5 yr) aligns with the evolutionary phase of Blue Hot DOGs, suggesting AGN feedback operates persistently during this transitional stage.}, archive = {J_ApJ}, author = {Chao Liu and Chao-Wei Tsai and Peter R. M. Eisenhardt and Hyunsung D. Jun and Guodong Li and Jingwen Wu and Roberto J. Assef and Andrew W. Blain and Maren Cosens and Tanio Díaz-Santos and Román Fernández Aranda and Lei Hao and Mai Liao and Shuai Liu and Daniel Stern and Andrey Vayner and Shelley Wright and Sherry Yeh}, doi = {10.3847/1538-4357/adc9b5}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {26}, shortjournal = {The Astrophys. J.}, title = {Multicomponent ionized gas outflows in the hot dust-obscured galaxy w2026+0716 with Keck/OSIRIS}, volume = {986}, year = {2025}, }
• (2025). A low metallicity massive contact binary star system candidate in WLM identified by hubble and james webb space telescope imaging. ApJ, 986(1), 25. (www)

  @article{ , abstract = {We present archival Hubble Space Telescope (HST) and JWST ultraviolet through near-infrared time series photometric observations of a massive minimal-contact binary candidate in the metal-poor galaxy Wolf–Lundmark–Melotte ( Z = 0.14 Z ⊙ ). This discovery marks the lowest metallicity contact binary candidate observed to date. We determine the nature of the two stars in the binary by using the eclipsing binary modeling software PHysics Of Eclipsing BinariEs ( PHOEBE ) to train a neural network to fit our observed panchromatic multiepoch photometry. The best-fit model consists of two hot main-sequence stars ( {T}_{1}=2980{0}_{-1700}^{+2300} K, {M}_{1}=1{6}_{-3}^{+2} M ⊙ , and {T}_{2}=1800{0}_{-5000}^{+5000} K, {M}_{2}={7}_{-3}^{+5} M ⊙ ). We discuss plausible evolutionary paths for the system, and suggest the system is likely to be currently in a contact phase. Future spectroscopy will help to further narrow down evolutionary pathways. This work showcases a novel use of data of JWST and HST imaging originally taken to characterize RR Lyrae. We expect time series imaging from LSST, BlackGEM, etc. to uncover similar types of objects in nearby galaxies.}, archive = {J_ApJ}, author = {Maude Gull and Daniel R. Weisz and Kareem El-Badry and Jan Henneco and Alessandro Savino and Meredith Durbin and Yumi Choi and Roger E. Cohen and Andrew A. Cole and Matteo Correnti and Julianne J. Dalcanton and Karoline M. Gilbert and Steven R. Goldman and Puragra Guhathakurta and Kristen B. W. McQuinn and Max J. B. Newman and Evan D. Skillman and Benjamin F. Williams}, doi = {10.3847/1538-4357/adca39}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {25}, shortjournal = {The Astrophys. J.}, title = {A low metallicity massive contact binary star system candidate in WLM identified by hubble and james webb space telescope imaging}, volume = {986}, year = {2025}, }
• (2025). Galaxy cluster characterization with machine learning techniques. ApJ, 986(1), 24. (www)

  @article{ , abstract = {We present an analysis of the X-ray properties of the galaxy cluster population in the z = 0 snapshot of the IllustrisTNG simulations, utilizing machine learning techniques to perform clustering and regression tasks. We examine five properties of the hot gas (the central cooling time, the central electron density, the central entropy excess, the concentration parameter, and the cuspiness) which are commonly used as classification metrics to identify cool core (CC), weak cool core (WCC) and non-cool core (NCC) clusters of galaxies. Using mock Chandra X-ray images as inputs, we first explore an unsupervised clustering scheme to see how the resulting groups correlate with the CC/WCC/NCC classification based on the different criteria. We observe that the groups replicate almost exactly the separation of the galaxy cluster images when classifying them based on the concentration parameter. We then move on to a regression task, utilizing a ResNet model to predict the value of all five properties. The network is able to achieve a mean percentage error of 1.8% for the central cooling time, and a balanced accuracy of 0.83 on the concentration parameter, making them the best-performing metrics. Finally, we use simulation-based inference to extract posterior distributions for the network predictions. Our neural network simultaneously predicts all five classification metrics using only mock Chandra X-ray images. This study demonstrates that machine learning is a viable approach for analyzing and classifying the large galaxy cluster data sets that will soon become available through current and upcoming X-ray surveys, such as the extended Roentgen Survey with an Imaging Telescope Array.}, archive = {J_ApJ}, author = {M. Sadikov and J. Hlavacek-Larrondo and L. Perreault-Levasseur and C. L. Rhea and M. McDonald and M. Ntampaka and J. ZuHone}, doi = {10.3847/1538-4357/adcd69}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {24}, shortjournal = {The Astrophys. J.}, title = {Galaxy cluster characterization with machine learning techniques}, volume = {986}, year = {2025}, }
• (2025). Multifluid and kinetic 2D and 3D simulations of thermal Farley–Buneman instability turbulence in the solar chromosphere. ApJ, 986(1), 23. (www)

  @article{ , abstract = {Models currently fail to reproduce observations of the coldest regions in the Sun's atmosphere, though recent work suggests the thermal Farley–Buneman instability (TFBI) may play a critical role. This meter-scale, electrostatic, multifluid plasma instability causes turbulence and heating in the coldest regions of the solar chromosphere. This paper describes how TFBI turbulence and heating varies across multifluid 2D, kinetic 2D, and kinetic 3D simulations. It also presents the first 3D simulations of the TFBI. We find that multifluid and kinetic 2D simulations produce similar results overall, despite using vastly different approaches. Additionally, our kinetic 3D simulations produce a similar or somewhat larger amount of heating compared to 2D, as contributions from the parallel electric field account for only (13 ± 2.5)% of the total turbulent heating in 3D.}, archive = {J_ApJ}, author = {Samuel Evans and Meers Oppenheim and Juan Martínez-Sykora and Yakov Dimant}, doi = {10.3847/1538-4357/adcd70}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {23}, shortjournal = {The Astrophys. J.}, title = {Multifluid and kinetic 2D and 3D simulations of thermal Farley–Buneman instability turbulence in the solar chromosphere}, volume = {986}, year = {2025}, }
• (2025). Systematic search for blue hypervelocity stars from LAMOST survey. ApJ, 986(1), 22. (www)

  @article{ , abstract = {Hypervelocity stars (HVSs) represent a unique class of objects capable of escaping the gravitational pull of the Milky Way due to extreme acceleration events, such as close encounters with the supermassive black hole at the Galactic center (GC), supernova explosions in binary systems, or multibody dynamical interactions. Finding and studying HVSs are crucial to exploring these ejection mechanisms, characterizing central black holes, probing the GC environment, and revealing the distribution of dark matter in our Galaxy. The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) spectroscopic surveys have so far identified four B-type unbound HVSs. To expand this sample with the second-phase LAMOST survey that started in 2018, we conducted a systematic search for early-type HVSs using the LAMOST Data Release 10. We identified 125 early-type high-velocity candidates with total velocities exceeding 300 km s −1 . Among them, we report 10 new unbound B- and A-type HVS candidates (designated LAMOST-HVS 5 through LAMOST-HVS 14), tripling the number of unbound HVSs previously identified by LAMOST. Kinematic analyses suggest that these newly discovered HVS candidates likely originated either from the GC or via dynamical interactions. Future high-resolution follow-up observations promise to refine the stellar parameters, distances, and elemental abundances of these candidates, thereby providing deeper insights into their origins and broadening their potential applications across astrophysics.}, archive = {J_ApJ}, author = {Yongkang Sun and Yang Huang and Jifeng Liu and Haozhu Fu and Huawei Zhang and Yinbi Li and Cuihua Du and Jianrong Shi and Xiao Kong}, doi = {10.3847/1538-4357/adcebe}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {22}, shortjournal = {The Astrophys. J.}, title = {Systematic search for blue hypervelocity stars from LAMOST survey}, volume = {986}, year = {2025}, }
• (2025). Model-agnostic cosmological inference with SDSS-IV eBOSS: Simultaneous probing for the background and perturbed universe. ApJ, 986(1), 21. (www)

  @article{ , abstract = {Here, we explore certain subtle features imprinted in data from the completed Sloan Digital Sky Survey IV (SDSS-IV) extended Baryon Oscillation Spectroscopic Survey (eBOSS) as a combined probe for the background and perturbed universe. We reconstruct the baryon acoustic oscillation and redshift space distortion observables as functions of redshift, using measurements from SDSS alone. We apply the multi-task Gaussian process framework to model the interdependencies of cosmological observables D M ( z )/ r d , D H ( z )/ r d , and fσ 8 ( z ), and track their evolution across different redshifts. Subsequently, we obtain a constrained three-dimensional phase space containing D M ( z )/ r d , D H ( z )/ r d , and fσ 8 ( z ) at different redshifts probed by the SDSS-IV eBOSS survey. Furthermore, assuming the Λ-cold dark matter (ΛCDM) model, we obtain constraints on model parameters Ω m , H 0 r d , σ 8, and S 8 at each redshift probed by SDSS-IV eBOSS. This indicates redshift-dependent trends in H 0 , Ω m , σ 8, and S 8 in the ΛCDM model, suggesting a possible inconsistency in the ΛCDM model. Ours is a template for model-independent extraction of information for both a background and perturbed universe using a single galaxy survey, taking into account all the existing correlations between background and perturbed observables and this can be easily extended to future DESI-3YR as well as Euclid results.}, archive = {J_ApJ}, author = {Purba Mukherjee and Anjan A Sen}, doi = {10.3847/1538-4357/adcee8}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {21}, shortjournal = {The Astrophys. J.}, title = {Model-agnostic cosmological inference with SDSS-IV eBOSS: Simultaneous probing for the background and perturbed universe}, volume = {986}, year = {2025}, }
• (2025). A thorough exploration of the metal-rich massive open cluster NGC 6253: Focusing on membership, binaries, stragglers, and mass function. ApJ, 986(1), 20. (www)

  @article{ , abstract = {This study provides an in-depth analysis of the ancient open galactic cluster NGC 6253, characterized by the presence of both blue and yellow straggler stars. Utilizing a hybrid approach that integrates DBSCAN and Gaussian mixture models with GAIA Data Release 3, we effectively identified the cluster members, discovering 11 blue and 7 yellow stragglers. The structure of the cluster considerably exceeds its tidal radius, which implies that there is an evident tidal tail structure. A calculated relaxation time of 32.469 Myr, which is considerably shorter than its 3.5 Gyr age, indicates that NGC 6253 has attained dynamic relaxation. The mass segregation timescale observed for most stars in our sample is brief compared to the cluster's age, offering strong evidence of mass segregation. Orbital integration using the MWPotential2014 model and analysis of binary members further corroborate our results. The birth radius of 6.78 kpc suggests formation within the solar circle. Our research into the present mass function reveals a top-heavy distribution common to both single and binary star populations. Additionally, our analysis shows that among binary systems, more massive binaries are more centrally located compared to their less massive counterparts, underscoring the significant role of binary stars in shaping the cluster's overall mass distribution.}, archive = {J_ApJ}, author = {Huanbin Chi and Feng Wang}, doi = {10.3847/1538-4357/adcf22}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {20}, shortjournal = {The Astrophys. J.}, title = {A thorough exploration of the metal-rich massive open cluster NGC 6253: Focusing on membership, binaries, stragglers, and mass function}, volume = {986}, year = {2025}, }
• (2025). Using machine learning method for variable star classification using the TESS sectors 1–57 data. ApJ, 986(1), 19. (www)

  @article{ , abstract = {The Transiting Exoplanet Survey Satellite is a wide-field all-sky survey mission designed to detect Earth-sized exoplanets. After over 4 yr of photometric surveys, data from sectors 1–57, including approximately 1,050,000 light curves with a 2 minute cadence, were collected. By crossmatching the data with Gaia's variable star catalogue, we obtained labeled data sets for further analysis. Using a random forest classifier, we performed classification of variable stars and designed distinct classification processes for each subclass: 6770 EA, 2971 EW, 980 CEP, 8347 DSCT, 457 RRab, 404 RRc, and 12,348 ROT were identified. Each variable star was visually inspected to ensure the reliability and accuracy of the compiled catalog. Subsequently, we ultimately obtained 6046 EA, 3859 EW, 2058 CEP, 8434 DSCT, 482 RRab, 416 RRc, and 9694 ROT, and a total of 14,092 new variable stars were discovered.}, archive = {J_ApJ}, author = {Li-Heng Wang and Kai Li and Xiang Gao and Ya-Ni Guo and Guo-You Sun}, doi = {10.3847/1538-4357/add159}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {19}, shortjournal = {The Astrophys. J.}, title = {Using machine learning method for variable star classification using the TESS sectors 1–57 data}, volume = {986}, year = {2025}, }
• (2025). SMILES: Potentially higher ionizing photon production efficiency in overdense regions. ApJ, 986(1), 18. (www)

  @article{ , abstract = {The topology of reionization and the environments where galaxies efficiently produce ionizing photons are key open questions. For the first time, we investigate the trend between ionizing photon production efficiency, ξ ion , and galaxy overdensity, \mathrm{log}(1+\delta ) . We analyze the ionizing properties of 79 galaxies between 1.0 < z < 5.2 using JWST NIRSpec medium-resolution spectra from the Systematic Mid-infrared Instrument Legacy Extragalactic Survey (SMILES) program. Among these, 67 galaxies have H α coverage, spanning 1.0 < z < 3.1. The galaxy overdensity, \mathrm{log}(1+\delta ) , is measured using the JADES photometric catalog, which covers the SMILES footprint. For the subset with H α coverage, we find that \mathrm{log}{\xi }_{{\rm{ion}}} is positively correlated with \mathrm{log}(1+\delta ) , with a slope of 0.9{4}_{-0.46}^{+0.46} . Additionally, the mean ξ ion for galaxies in overdense regions ( \mathrm{log}(1+\delta )\gt 0.1 ) is 2.43 times that of galaxies in lower density regions ( \mathrm{log}(1+\delta )\lt 0.1 ). This strong trend is found to be independent of redshift evolution. Furthermore, our results confirm the robust correlations between ξ ion and the rest-frame equivalent widths of the [O iii ] or H α emission lines. Our results suggest that galaxies in high-density regions are efficient producers of ionizing photons.}, archive = {J_ApJ}, author = {Yongda Zhu and Stacey Alberts and Jianwei Lyu and Jane Morrison and George H. Rieke and Yang Sun and Jakob M. Helton and Zhiyuan Ji and Rachana Bhatawdekar and Nina Bonaventura and Andrew J. Bunker and Xiaojing Lin and Marcia J. Rieke and Pierluigi Rinaldi and Irene Shivaei and Christopher N. A. Willmer and Junyu Zhang}, doi = {10.3847/1538-4357/add263}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {18}, shortjournal = {The Astrophys. J.}, title = {SMILES: Potentially higher ionizing photon production efficiency in overdense regions}, volume = {986}, year = {2025}, }
• (2025). Characterizing chromospheric condensation with high-cadence si iv observations from IRIS. ApJ, 986(1), 17. (www)

  @article{ , abstract = {Chromospheric flare ribbons are believed to result from coronal magnetic energy released by reconnection and propagating down to the cooler, lower atmosphere. They offer an opportunity to study flare reconnection using chromospheric observations at a spatial and temporal resolution higher than typically available by direct coronal observation. Transient downflows, known as chromospheric condensations (CCs), often occur at the leading edge of a ribbon as a prompt response to the energy input. These have properties that have recently been shown to relate to the coronal energy release process driving them. We use a set of IRIS observations of flare ribbons, made at high cadence in the sit-and-stare mode, to identify and analyze a sample of 134 CC episodes. Among this sample, 132 episodes have at least one time frame that exhibited a double-Gaussian profile. Clear CC appears to occur in only about one fifth of all ribbon pixels, indicating that flare energy release is necessary but not sufficient for producing the characteristic form of CC. We find that condensation pixels form clusters averaging 1 arcsec in extent, all undergoing similar and concurrent time evolution. This suggests that coronal reconnection and associated energy release occur in localized patches whose spatial extent maps to around 1 arcsec in the chromosphere.}, archive = {J_ApJ}, author = {Chunming Zhu and Willow Reed and Alysa Derks and Dana Longcope}, doi = {10.3847/1538-4357/add3fc}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {17}, shortjournal = {The Astrophys. J.}, title = {Characterizing chromospheric condensation with high-cadence si iv observations from IRIS}, volume = {986}, year = {2025}, }
• (2025). On the origin of spectral features observed during thermonuclear X-ray bursts and in the aftermath emission of a long burst from 4U 1820–30. ApJ, 986(1), 16. (www)

  @article{ , abstract = {We study 15 thermonuclear X-ray bursts from 4U 1820–30 observed with the Neutron Star Interior Composition Explorer (NICER). We find evidence of a narrow emission line at 1.0 keV and three absorption lines at 1.7, 3.0, and 3.75 keV, primarily around the photospheric radius expansion phase of most bursts. The 1.0 keV emission line remains constant, while the absorption features, attributed to wind-ejected species, are stable but show slight energy shifts, likely due to combined effects of Doppler and gravitational redshifts. We also examine with NICER the "aftermath" of a long X-ray burst (a candidate superburst observed by MAXI) on 2021 August 23 and 24. The aftermath emission recovers within half a day from a flux depression. During this recovery phase, we detect two emission lines at 0.7 and 1 keV, along with three absorption lines whose energies decrease to 1.57, 2.64, and 3.64 keV. Given the nature of the helium white dwarf companion, these absorption lines during the aftermath may originate from an accretion flow, but only if the accretion environment is significantly contaminated by nuclear ashes from the superburst. This provides evidence of temporary metal enhancement in the accreted material due to strong wind loss. Moreover, we suggest that the absorption features observed during the short X-ray bursts and in the superburst aftermath share a common origin in heavy nuclear ashes enriched with elements like Si, Ar, Ca, or Ti, either from the burst wind or from an accretion flow contaminated by the burst wind.}, archive = {J_ApJ}, author = {Gaurava K. Jaisawal and Jérôme Chenevez and Tod E. Strohmayer and Hendrik Schatz and J. J. M. in ’t Zand and Tolga Güver and Diego Altamirano and Zaven Arzoumanian and Keith C. Gendreau}, doi = {10.3847/1538-4357/adcc24}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {16}, shortjournal = {The Astrophys. J.}, title = {On the origin of spectral features observed during thermonuclear X-ray bursts and in the aftermath emission of a long burst from 4U 1820–30}, volume = {986}, year = {2025}, }
• (2025). The SOFIA massive (SOMA) star formation survey. v. clustered protostars. ApJ, 986(1), 15. (www)

  @article{ , abstract = {We present ∼8–40 μ m SOFIA-FORCAST images of seven regions of "clustered" star formation as part of the SOFIA Massive Star Formation Survey. We identify a total of 34 protostar candidates and build their spectral energy distributions (SEDs). We fit these SEDs with a grid of radiative transfer models based on the turbulent core accretion (TCA) theory to derive key protostellar properties, including initial core mass, M c , clump environment mass surface density, Σ cl , and current protostellar mass, m * . We also carry out empirical graybody (GB) estimation of Σ cl , which allows a case of restricted SED fitting within the TCA model grid. We also release version 2.0 of the open-source Python package sedcreator , which is designed to automate the aperture photometry and SED building and fitting process for sources in clustered environments, where flux contamination from close neighbors typically complicates the process. Using these updated methods, SED fitting yields values of M c ∼ 30–200 M ⊙ , Σ cl,SED ∼ 0.1–3 g cm −2 , and m * ∼ 4–50 M ⊙ . The GB fitting yields smaller values of Σ cl,GB ≲ 1 g cm −2 . From these results, we do not find evidence for a critical Σ cl needed to form massive (≳8 M ⊙ ) stars. However, we do find tentative evidence for a dearth of the most massive ( m * ≳ 30 M ⊙ ) protostars in the clustered regions, suggesting a potential impact of environment on the stellar initial mass function.}, archive = {J_ApJ}, author = {Zoie Telkamp and Rubén Fedriani and Jonathan C. Tan and Chi-Yan Law and Yichen Zhang and Adele Plunkett and Samuel Crowe and Yao-Lun Yang and James M. De Buizer and Maria T. Beltran and Mélisse Bonfand and Ryan Boyden and Giuliana Cosentino and Prasanta Gorai and Mengyao Liu and Viviana Rosero and Kotomi Taniguchi and Kei E. I. Tanaka and Tatiana M. Rodríguez}, doi = {10.3847/1538-4357/adcd79}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {15}, shortjournal = {The Astrophys. J.}, title = {The SOFIA massive (SOMA) star formation survey. v. clustered protostars}, volume = {986}, year = {2025}, }
• (2025). Multimessenger signatures of a deformed magnetar in gamma-ray bursts. ApJ, 986(1), 14. (www)

  @article{ , abstract = {We study the evolution of a newly formed magnetized neutron star (NS) as a power source of gamma-ray bursts (GRBs) in the light of both gravitational-wave (GW) and electromagnetic (EM) radiation. The compressible and incompressible fluids are employed in order to model the secular evolution of stable Maclaurin spheroids. It is shown that the GW and EM emissions evolve as a function of eccentricity and rotational frequency with time. We find that the luminosity characteristics crucially depend on NS parameters such as magnitude and structure of magnetic field, ellipticity, and the equation of state (EoS) of the fluid. The presence of X-ray flares, whose origins are not yet well understood, can be captured in our model regarding some specific nuclear EoSs. Our model allows us to explain flares that occur within the wide range of 10–10 4 s and the peak EM luminosity in the order of 10 46 –10 51 erg s −1 by using a reasonable set of parameters, such as magnetic field strength around 10 14 –10 16 G and the quadrupole-to-dipole ratio of magnetic field up to 500. By applying our model to a sample of GRB X-ray flares observed by the Swift/X-ray Telescope, we try to constraint the crucial parameters of a deformed magnetar via a Markov Chain Monte Carlo fitting method. Our analysis shows that ongoing and upcoming joint multimessenger detections can be used to understand the nature of a GRB's central engine and its evolution at the ​​​​​​early times of the burst formation.}, archive = {J_ApJ}, author = {Parisa Hashemi and Soroush Shakeri and Yu Wang and Liang Li and Rahim Moradi}, doi = {10.3847/1538-4357/adceb0}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {14}, shortjournal = {The Astrophys. J.}, title = {Multimessenger signatures of a deformed magnetar in gamma-ray bursts}, volume = {986}, year = {2025}, }
• (2025). An investigation of disk thickness in m51 from hα, paα, and mid-infrared power spectra. ApJ, 986(1), 13. (www)

  @article{ , abstract = {Power spectra (PS) of high-resolution images of M51 (NGC 5194) taken with the Hubble Space Telescope and the James Webb Space Telescope (JWST) have been examined for evidence of disk thickness in the form of a change in slope between large scales, which map two-dimensional correlated structures, and small scales, which map three-dimensional correlated structures. Such a slope change is observed here in H α , and possibly Pa α , using average PS of azimuthal intensity scans that avoid bright peaks. The physical scale of the slope change occurs at ∼120 pc and ∼170 pc for these two transitions, respectively. A radial dependence in the shape of the H α PS also suggests that the length scale drops from ∼180 pc at 5 kpc, to ∼90 pc at 2 kpc, to ∼25 pc in the central ∼kpc. We interpret these lengths as comparable to the thicknesses of the star-forming disk traced by H ii regions. The corresponding emission measure is ∼100 times larger than what is expected from the diffuse ionized gas. The PS of JWST Mid-IR Instrument images in eight passbands have more gradual changes in slope, making it difficult to determine a specific value of the thickness for this emission.}, archive = {J_ApJ}, author = {Bruce G. Elmegreen and Daniela Calzetti and Angela Adamo and Karin Sandstrom and Daniel Dale and Varun Bajaj and Martha L. Boyer and Ana Duarte-Cabral and Ryan Chown and Matteo Correnti and Julianne J. Dalcanton and Bruce T. Draine and Brandt Gaches and John S. Gallagher and Kathryn Grasha and Benjamin Gregg and Leslie K. Hunt and Kelsey E. Johnson and Robert Kennicutt and Ralf S. Klessen and Adam K. Leroy and Sean Linden and Anna F. McLeod and Matteo Messa and Göran Östlin and Mansi Padave and Julia Roman-Duval and J. D. Smith and Fabian Walter and Tony D. Weinbeck}, doi = {10.3847/1538-4357/adcee6}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {13}, shortjournal = {The Astrophys. J.}, title = {An investigation of disk thickness in m51 from hα, paα, and mid-infrared power spectra}, volume = {986}, year = {2025}, }
• (2025). The role of pressure in the structure and stability of GMCs in the andromeda galaxy. ApJ, 986(1), 12. (www)

  @article{ , abstract = {We revisit the role of pressure in the structure, stability, and confinement of Giant Molecular Clouds (GMCs) in light of recently published observations and analysis of the GMCs in the Andromeda galaxy (M31). That analysis showed that, in the absence of any external pressure, most GMCs (57% by number) in M31 would be gravitationally unbound. Here, after a more detailed examination of the global measurements of surface densities and velocity dispersions, we find that GMCs in M31, when they can be traced to near their outermost molecular boundaries, require external pressures for confinement that are consistent with estimates for the mid-plane pressure of this galaxy. We introduce and apply a novel methodology to measure the radial profile of internal pressure within any GMC that is spatially resolved by the CO observations. We show that, for the best-resolved examples in M31, the internal pressures increase steeply with surface density in a power-law fashion with p int ∼ Σ 2 . At high surface densities, many of these extragalactic GMC profiles break from the single power-law and exhibit upward curvature. Both these characteristics of the variation of internal pressure with surface density are in agreement with theoretical expectations for hydrostatic equilibrium at each radial surface of a GMC, including the outermost boundary.}, archive = {J_ApJ}, author = {Charles J. Lada and Jan Forbrich and Mark R. Krumholz and Eric Keto}, doi = {10.3847/1538-4357/adcf9d}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {12}, shortjournal = {The Astrophys. J.}, title = {The role of pressure in the structure and stability of GMCs in the andromeda galaxy}, volume = {986}, year = {2025}, }
• (2025). A unified, physical framework for mean motion resonances. ApJ, 986(1), 11. (www)

  @article{ , abstract = {The traditional approach to analyzing mean motion resonances (MMRs) is through the canonical perturbation theory. While this is a powerful method, its generality leads to complicated combinations of variables that are challenging to interpret and require looking up numerical coefficients particular to every different resonance. In this paper, we develop simpler scaling relations in the limit where orbits are closely spaced (period ratios ≲2), and interplanetary interactions can be approximated by only considering the close approaches each time the inner planet overtakes the outer at the conjunction. We develop geometric arguments for several powerful results: (i) that p : p − q MMRs of the same order q are all rescaled versions of one another, (ii) that the general case of two massive planets on closely spaced, eccentric, coplanar orbits can be approximately mapped onto the much simpler case of an eccentric test particle perturbed by a massive planet on a coplanar circular orbit, and (iii) that, while the effects of consecutive conjunctions add up coherently for first-order ( p : p − 1) MMRs, they partially cancel for p : p − q MMRs with order q > 1, providing a physical explanation for why these higher-order MMRs are weaker and can often be ignored. Finally, we provide simple expressions for the widths of MMRs and their associated oscillation frequencies that are universal to all closely spaced MMRs of a given order q , in the pendulum approximation.}, archive = {J_ApJ}, author = {Daniel Tamayo and Samuel Hadden}, doi = {10.3847/1538-4357/adc1c4}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {11}, shortjournal = {The Astrophys. J.}, title = {A unified, physical framework for mean motion resonances}, volume = {986}, year = {2025}, }
• (2025). Thermal desorption kinetics, binding energies, and entrapment of methyl mercaptan ices. ApJ, 986(1), 10. (www)

  @article{ , abstract = {Organosulfur species are potential major carriers of sulfur in the interstellar medium, as well as interesting ingredients in prebiotic chemistry. The most fundamental question regarding these species is under which conditions they reside in the gas versus solid phase. Here, we characterize the thermal desorption kinetics, binding energies, and entrapment of the organosulfur methyl mercaptan (CH 3 SH, or MeSH) in different ice environments, comparing them with those of methanol (CH 3 OH, or MeOH) ices. The derived multilayer (pure MeSH–MeSH) and submonolayer (layered MeSH–H 2 O) binding energies are surprisingly similar, corresponding to snow line locations where the disk midplane temperature is ∼105 K. In both H 2 O-dominated and more realistic H 2 O:CO 2 -dominated ices, 100% of the MeSH is entrapped, almost exclusively desorbing at the molecular volcano desorption peak, indicating that MeSH is retained at the water snow line if initially mixed with water ice during formation. Additionally, the presence of MeSH in an ice mixture enhances the entrapment of CO 2 and MeOH (up to 100%) until the onset of volcano desorption; without MeSH, both desorb at their respective pure desorption temperatures and also codesorb with water. Compared to MeOH, MeSH binds less well to water, explaining why MeSH escapes during water ice crystallization rather than codesorbing with water. These results show that the larger relative size of MeSH compared to MeOH significantly impacts its ability to bind to water and its entrapment efficiency. Therefore, molecular size plays an important role in the adsorption and retention of S-bearing organics and, in turn, other volatiles in ices.}, archive = {J_ApJ}, author = {Suchitra Narayanan and Elettra L. Piacentino and Karin I. Öberg and Mahesh Rajappan}, doi = {10.3847/1538-4357/adc7b6}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {10}, shortjournal = {The Astrophys. J.}, title = {Thermal desorption kinetics, binding energies, and entrapment of methyl mercaptan ices}, volume = {986}, year = {2025}, }
• (2025). Cue: A fast and flexible photoionization emulator for modeling nebular emission powered by almost any ionizing source. ApJ, 986(1), 9. (www)

  @article{ , abstract = {The complex physics governing nebular emission in galaxies, particularly in the early Universe, often defy simple low-dimensional models. This has proven to be a significant barrier in understanding the (often diverse) ionizing sources powering this emission. We present Cue , 10 a highly flexible tool for interpreting nebular emission across a wide range of abundances and ionizing conditions of galaxies at different redshifts. Unlike typical nebular models used to interpret extragalactic nebular emission, our model does not require a specific ionizing spectrum as a source, instead approximating the ionizing spectrum with a four-part piecewise power law. We train a neural net emulator based on the CLOUDY photoionization modeling code and make self-consistent nebular continuum and line emission predictions. Along with the flexible ionizing spectra, we allow freedom in [O/H], [N/O], [C/O], gas density, and total ionizing photon budget. This flexibility allows us to either marginalize over or directly measure the incident ionizing radiation, thereby directly interrogating the source of the ionizing photons in distant galaxies via their nebular emission. Our emulator demonstrates a high accuracy, with ∼1% uncertainty in predicting the nebular continuum and ∼5% uncertainty in the emission lines. Mock tests suggest Cue is well calibrated and produces useful constraints on the ionizing spectra when the signal-to-noise ratio of H α is ≳10, and furthermore capable of distinguishing between the ionizing spectra predicted by single and binary stellar models. The computational efficiency of neural networks facilitates future applications of Cue for rapid modeling of the nebular emission in large samples and Monte Carlo sampling techniques.}, archive = {J_ApJ}, author = {Yijia Li and Joel Leja and Benjamin D. Johnson and Sandro Tacchella and Rebecca Davies and Sirio Belli and Minjung Park and Razieh Emami}, doi = {10.3847/1538-4357/adcab4}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {9}, shortjournal = {The Astrophys. J.}, title = {Cue: A fast and flexible photoionization emulator for modeling nebular emission powered by almost any ionizing source}, volume = {986}, year = {2025}, }
• (2025). XMM-newton observations of the high temperature plasma in the large magellanic cloud supernova remnant N132D. ApJ, 986(1), 8. (www)

  @article{ , abstract = {We present an analysis of the archival XMM-Newton observations of the Large Magellanic Cloud (LMC) supernova remnant N132D totaling more than 500 ks. We focus on the high temperature plasma ( kT e ∼ 4.5 keV) that is responsible for the high energy continuum and exciting the Fe K emission. An image analysis shows that the Fe K emission is mainly concentrated in the southern part of the remnant interior to the region defined by the forward shock. This Fe K distribution would be consistent with an asymmetric distribution of the Fe ejecta and/or an asymmetric interaction between the reverse shock and the Fe ejecta. We compare the EPIC-pn and EPIC-MOS spectra in the 3.0–12.0 keV bandpass with a model based on RGS data plus a higher temperature component, in collisional ionization equilibrium (CIE), or nonequilibrium (both ionizing and recombining). We find that the data are equally well fitted by the CIE and ionizing models. Assuming the CIE and ionizing spectral models, the Fe in this high temperature component is significantly enhanced with respect to typical LMC abundances. We can place only an upper limit on the neutral Fe K line. We conclude that the Fe K emission is due to ejecta heated by the reverse shock given the spatial distribution, relatively high temperature, and enhanced abundance. We estimate the progenitor mass based on the Ca/Fe and Ni/Fe mass ratios to be 13 ≤ M P ≤ 15 M ⊙ .}, archive = {J_ApJ}, author = {Adam R. Foster and Paul P. Plucinsky and Terrance J. Gaetz and Xi Long and Diab Jerius}, doi = {10.3847/1538-4357/adcd61}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {8}, shortjournal = {The Astrophys. J.}, title = {XMM-newton observations of the high temperature plasma in the large magellanic cloud supernova remnant N132D}, volume = {986}, year = {2025}, }
• (2025). The atacama cosmology telescope: Systematic transient search of single observation maps. ApJ, 986(1), 7. (www)

  @article{ , abstract = {We conduct a systematic search for astrophysical transients using data from the Atacama Cosmology Telescope. The data were taken from 2017 to 2022 in three frequency bands spanning 77 to 277 GHz. In this paper, we present a pipeline for transient detection using single-observation maps where each pixel of a map contains one observation with an integration time of approximately 4 minutes. We detect 34 transient events at 27 unique locations. All but two of the transients are associated with Galactic stars and exhibit a wide range of properties. We also detect an event coincident with the classical nova YZ Ret and one event consistent with a flaring active galactic nucleus. We notably do not detect any reverse shock emission from gamma-ray bursts, a nondetection that may be in tension with current models.}, archive = {J_ApJ}, author = {Emily Biermann and Yaqiong Li and Sigurd Naess and Steve K. Choi and Susan E. Clark and Mark Devlin and Jo Dunkley and P. A. Gallardo and Yilun Guan and Allen Foster and Matthew Hasselfield and Carlos Hervías-Caimapo and Matt Hilton and Adam D. Hincks and Anna Y. Q. Ho and John C. Hood and Kevin M. Huffenberger and Arthur Kosowsky and Michael D. Niemack and John Orlowski-Scherer and Lyman Page and Bruce Partridge and Maria Salatino and Cristóbal Sifón and Suzanne T. Staggs and Cristian Vargas and Edward J. Wollack}, doi = {10.3847/1538-4357/adce70}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {7}, shortjournal = {The Astrophys. J.}, title = {The atacama cosmology telescope: Systematic transient search of single observation maps}, volume = {986}, year = {2025}, }
• (2025). Revisiting the X-ray polarization of the shell of cassiopeia a using spectropolarimetric analysis. ApJ, 986(1), 6. (www)

  @article{ , abstract = {X-ray synchrotron radiation is expected to be highly polarized. Thanks to the Imaging X-ray Polarimetry Explorer (IXPE), it is now possible to evaluate the degree of X-ray polarization in sources such as supernova remnants (SNRs). Jointly using IXPE data and high-resolution Chandra observations, we perform a spatially resolved spectropolarimetric analysis of SNR Cassiopeia A (Cas A). We focus on the 3–6 keV energy band on regions near the shell dominated by nonthermal synchrotron emission. By combining IXPE's polarization sensitivity with Chandra's higher spatial and spectral resolution, we constrain the local polarization degree (PD) and polarization angle across the remnant. Our analysis reveals PD values ranging locally from 10% to 26%, showing significant regional variations that underscore the complex magnetic field morphology of Cas A. The polarization vectors indicate a predominantly radial magnetic field, consistent with previous studies. Thanks to the improved modeling of thermal contamination using Chandra data, we retrieve higher PD values compared to earlier IXPE analysis and more significant detections with respect to the standard IXPEOBSSIM analysis. Finally, we also estimate the degree of magnetic turbulence η from the measured photon index and PD, under the assumption of an isotropic fluctuating field across the shell of Cas A.}, archive = {J_ApJ}, author = {A. Mercuri and E. Greco and J. Vink and R. Ferrazzoli and S. Perri}, doi = {10.3847/1538-4357/adcedb}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {6}, shortjournal = {The Astrophys. J.}, title = {Revisiting the X-ray polarization of the shell of cassiopeia a using spectropolarimetric analysis}, volume = {986}, year = {2025}, }
• (2025). Constraints on the galaxy formation models during the epoch of reionization with high-redshift observations. ApJ, 986(1), 5. (www)

  @article{ , abstract = {We use high-resolution N -body dark matter simulations and L-G alaxies semianalytical galaxy formation models to explore the high- z galaxy properties and estimate the budget of ionizing photons. The parameters within L - G alaxies are obtained using a Markov Chain Monte Carlo (MCMC) method with high- z galaxy observations from JWST and other telescopes. We consider two versions of L-G alaxies , with and without dust correction on galaxy UV luminosities. With the best-fit parameters, both L-G alaxies 2015 and L-G alaxies 2020 reproduce well observations of UV luminosity functions, stellar mass functions, star formation rate densities, and ionizing photon emission efficiency. With the assumption of an escape fraction of 20%, all models produce more ionizing photons than the number of hydrogen atoms in the Universe at z > 6. The inclusion of dust correction within MCMC results in higher star formation efficiency, which predicts ∼50% more ionizing photons, with better consistency between the predicted stellar mass functions and observations.}, archive = {J_ApJ}, author = {Qing-Bo Ma and Xiao-Rong Chen and Ming Li and Qi Guo and Benedetta Ciardi and Anshuman Acharya and Xin Wang}, doi = {10.3847/1538-4357/add015}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {5}, shortjournal = {The Astrophys. J.}, title = {Constraints on the galaxy formation models during the epoch of reionization with high-redshift observations}, volume = {986}, year = {2025}, }
• (2025). Further investigations into emission components of PSR b0950+08 and correlations between them with single pulses. ApJ, 986(1), 4. (www)

  @article{ , abstract = {With the phase-to-phase cross-correlation method, we analyzed the single pulses of PSR B0950+08 obtained at the Five-hundred-meter Aperture Spherical radio Telescope. The correlation map produced with the single pulses reveals a modulation of the correlation coefficients, which are between the intensities at different phases of the single pulses. The modulation varies by a period of two phase bins with 2048 bins over the whole pulse phase. Such a modulation is related to the microstructures of the single pulses and may ultimately imply that the Lorentz factors of the charged particles in the pulsar magnetosphere are highly similar along the line of sight trajectory. The modulation rule reverses after a constant phase separation of 191\mathop{.}\limits^{^\circ }43 . It also reverses around the peak phase of the mean pulse profile, implying that the Lorentz factors are different from the normal value around the reversal phase. According to the analyses with the correlation map, we propose that the bridge emission between the main pulse (MP) and its preceding interpulse (IP) is the overlap of the MP and the IP. For the "weak emission" trailing the MP, it is identified as an independent profile component. There are strong emissions from the IP but no giant pulse from the MP during this observation. The correlation between the IPs and the MPs is mainly dominated by the positive correlations between the subcomponents of the IP and one subcomponent of the MP, according to our analyses.}, archive = {J_ApJ}, author = {Jie Liu and Zhen Yan and Hao Tong and Hong-Guang Wang and Zhi-Qiang Shen and Rui Wang and Xiao-Wei Wang and Zhi-Peng Huang}, doi = {10.3847/1538-4357/add1d9}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {4}, shortjournal = {The Astrophys. J.}, title = {Further investigations into emission components of PSR b0950+08 and correlations between them with single pulses}, volume = {986}, year = {2025}, }
• (2025). Tracking the jet-like corona of black hole swift j1727.8−1613 during a flare state through type-C quasiperiodic oscillations. ApJ, 986(1), 3. (www)

  @article{ , abstract = {Type-C quasiperiodic oscillations (QPOs) in black hole X-ray transients typically manifest in the low-hard and hard-intermediate states. This study presents a detailed spectral and temporal analysis of the black hole candidate Swift J1727.8−1613 using NICER observations from 2023 August and September, with a focus on the first flare period. We detected Type-C QPOs whose centroid frequency increased from 0.33 Hz to 2.63 Hz. An additional increase in frequency was observed when the outburst entered a flare period. The time-averaged spectra, along with the rms and phase-lag spectra of the QPOs, were jointly fitted using the time-dependent Comptonization model vkompthdk to examine the geometry of the corona during this flare. Correlations between spectral and temporal properties suggest that the detected type-C QPOs are primarily modulated by Lense–Thirring precession. Leveraging simultaneous radio observations that indicate discrete jet ejections, we propose a scenario to describe the coevolution of the disk–corona–jet during a flare (∼3 days). This scenario is partially supported for the first time by polarization data in the soft gamma-ray band from the IBIS instrument on board the International Gamma-Ray Astrophysics Laboratory. A phenomenological analysis of the corona scenario was also conducted.}, archive = {J_ApJ}, author = {Jie Liao and Ning Chang and Lang Cui and Pengfei Jiang and Didong Mou and Yongfeng Huang and Tao An and Luis C. Ho and Hua Feng and Yu-Cong Fu and Hongmin Cao and Ashutosh Tripathi and Xiang Liu}, doi = {10.3847/1538-4357/add264}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {3}, shortjournal = {The Astrophys. J.}, title = {Tracking the jet-like corona of black hole swift j1727.8−1613 during a flare state through type-C quasiperiodic oscillations}, volume = {986}, year = {2025}, }
• (2025). Uncertainties in the inference of internal structure: The case of TRAPPIST-1 f. ApJ, 986(1), 2. (www)

  @article{ , abstract = {We use the TRAPPIST-1 system as a model observation of Earth-like planets. The densities of these planets being 1%–10% less than the Earth suggest that the outer planets may host significant hydrospheres. We explore the uncertainty in water mass fraction (wmf) from observed mass and radius. We investigate the interior structure of TRAPPIST-1 f (T1-f) using the open-source solver MAGRATHEA and varying assumptions in the interior model. We find that T1-f likely has a wmf of 16.2% ± 9.9% when considering all possible core mass fractions, and requires 6.9% ± 2.0% water at an Earth-like mantle-to-core ratio. We quantify uncertainties from observational precision, model assumptions, and experimental and theoretical data on the bulk modulus of planet-building materials. We show that observational uncertainties are smaller than model assumptions of mantle mineralogy and core composition but larger than hydrosphere, temperature, and equation-of-state assumptions/uncertainties. Our findings show that while precise mass and radius measurements are crucial, uncertainties in planetary models can often outweigh those from observations, emphasizing the importance of refining both theoretical models and experimental data to better understand exoplanet interiors.}, archive = {J_ApJ}, author = {David R. Rice and Chenliang Huang and Jason H. Steffen and Allona Vazan}, doi = {10.3847/1538-4357/add34b}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {2}, shortjournal = {The Astrophys. J.}, title = {Uncertainties in the inference of internal structure: The case of TRAPPIST-1 f}, volume = {986}, year = {2025}, }
• (2025). Statistical trends in JWST transiting exoplanet atmospheres. ApJ, 986(1), 1. (www)

  @article{ , abstract = {Our brains are hardwired for pattern recognition as correlations are useful for predicting and understanding nature. As more exoplanet atmospheres are being characterized with JWST, we are starting to unveil their properties on a population level. Here we present a framework for comparing exoplanet transmission spectroscopy from 3 to 5 μ m with four bands: L (2.9–3.7 μ m), SO 2 (3.95–4.1 μ m), CO 2 (4.25–4.4 μ m), and CO (4.5–4.9 μ m). Together, the four bands cover the major carbon-, oxygen-, nitrogen-, and sulfur-bearing molecules including H 2 O, CH 4 , NH 3 , H 2 S, SO 2 , CO 2 , and CO. Among the eight high-precision gas giant exoplanet planet spectra we collect, we find strong correlations between the SO 2 – L index and planet mass ( r = −0.41 ± 0.09) and temperature ( r = −0.64 ± 0.08), indicating SO 2 preferably exists (SO 2 – L > −0.5) among low-mass (∼ <0.3 M J ) and cooler (∼ <1200 K) targets. We also observe strong temperature dependency for both CO 2 – L and CO – L indices. Under equilibrium chemistry and isothermal thermal structure assumptions, we find that the planet sample favors supersolar metallicity and a low C/O ratio (<0.7). In addition, the presence of a mass–metallicity correlation is favored over uniform metallicity with the eight planets. We further introduce the SO 2 – L versus CO 2 – L diagram, similar to the color–magnitude diagram for stars and brown dwarfs. All reported trends here will be testable and will be further quantified with existing and future JWST observations within the next few years.}, archive = {J_ApJ}, author = {Guangwei Fu and Kevin B. Stevenson and David K. Sing and Sagnick Mukherjee and Luis Welbanks and Daniel Thorngren and Shang-Min Tsai and Peter Gao and Joshua Lothringer and Thomas G. Beatty and Cyril Gapp and Thomas M. Evans-Soma and Romain Allart and Stefan Pelletier and Pa Chia Thao and Andrew W. Mann}, doi = {10.3847/1538-4357/ad7bb8}, journal = {The Astrophysical Journal}, month = {6}, number = {1}, pages = {1}, shortjournal = {The Astrophys. J.}, title = {Statistical trends in JWST transiting exoplanet atmospheres}, volume = {986}, year = {2025}, }
• (2025). Erratum: “The RESOLVE and ECO gas in galaxy groups initiative: The group finder and the group h i–Halo mass relation” (2023, ApJ, 956, 51). ApJ, 985(2), 270. (www)

  @article{ , archive = {J_ApJ}, author = {Zackary L. Hutchens and Sheila J. Kannappan and Andreas A. Berlind and Mehnaaz Asad and Kathleen D. Eckert and David V. Stark and Derrick S. Carr and Ella R. Castelloe and Andrew J. Baker and Kelley M. Hess and Amanda J. Moffett and Mark A. Norris and Darren Croton}, doi = {10.3847/1538-4357/add153}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {270}, shortjournal = {The Astrophys. J.}, title = {Erratum: “The RESOLVE and ECO gas in galaxy groups initiative: The group finder and the group h i–Halo mass relation” (2023, ApJ, 956, 51)}, volume = {985}, year = {2025}, }
• (2025). Erratum: “SIMPLE: Simple intensity map producer for line emission” (2023, ApJ, 958, 4). ApJ, 985(2), 269. (www)

  @article{ , archive = {J_ApJ}, author = {Maja Lujan Niemeyer and José Luis Bernal and Eiichiro Komatsu}, doi = {10.3847/1538-4357/add1d8}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {269}, shortjournal = {The Astrophys. J.}, title = {Erratum: “SIMPLE: Simple intensity map producer for line emission” (2023, ApJ, 958, 4)}, volume = {985}, year = {2025}, }
• (2025). Erratum: “Gravitational-wave and gravitational-wave memory signatures of core-collapse supernovae” (2024, ApJ, 975, 12). ApJ, 985(2), 268. (www)

  @article{ , archive = {J_ApJ}, author = {Lyla Choi and Adam Burrows and David Vartanyan}, doi = {10.3847/1538-4357/add6a6}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {268}, shortjournal = {The Astrophys. J.}, title = {Erratum: “Gravitational-wave and gravitational-wave memory signatures of core-collapse supernovae” (2024, ApJ, 975, 12)}, volume = {985}, year = {2025}, }
• (2025). Erratum: “Stellar β−-decay rate of 63Ni and its impact on the s-process nucleosynthesis in massive stars” (2025, ApJ, 984, 8). ApJ, 985(2), 267. (www)

  @article{ , archive = {J_ApJ}, author = {Xin-Xu Wang and Bao-Hua Sun and Toshitaka Kajino and Zhen-Yu He and Toshio Suzuki and Dong-Liang Fang and Zhong-Ming Niu}, doi = {10.3847/1538-4357/add6a7}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {267}, shortjournal = {The Astrophys. J.}, title = {Erratum: “Stellar β−-decay rate of 63Ni and its impact on the s-process nucleosynthesis in massive stars” (2025, ApJ, 984, 8)}, volume = {985}, year = {2025}, }
• (2025). Erratum: “Acceleration and substructure constraints in a quasar outflow” (2007, ApJ, 665, 174). ApJ, 985(2), 266. (www)

  @article{ , archive = {J_ApJ}, author = {Patrick B. Hall and Sarah I. Sadavoy and Damien Hutsemekers and John E. Everett and Alireza Rafiee}, doi = {10.3847/1538-4357/add71e}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {266}, shortjournal = {The Astrophys. J.}, title = {Erratum: “Acceleration and substructure constraints in a quasar outflow” (2007, ApJ, 665, 174)}, volume = {985}, year = {2025}, }
• (2025). Implementing continuous all-sky monitoring with the OVRO-LWA to identify prompt and precursor counterparts of gravitational wave events. ApJ, 985(2), 265. (www)

  @article{ , abstract = {A number of theoretical studies have proposed a prompt or precursor low-frequency radio counterpart to gravitational wave events detected by LIGO and Virgo. Detection of such events would offer a new window on the immediate environment of the merger and provide an avenue to rapid localization. However, identifying fast transients in real-time in localization regions spanning hundreds to thousands of square degrees presents severe technical challenges. To address these challenges, we present a novel technique embodied in the Time Machine, a system featuring a two-stage voltage buffer and subsequent processing pipeline designed for the Long Wavelength Array at the Owens Valley Radio Observatory. This array is developed to instantaneously image the entire viewable sky. We detail the system's buffer structure that allows data collection from several minutes before a trigger event, up to 30 minutes after an event. The processing of this voltage data involves beamforming and searching the full 90th-percentile localization region above the horizon with ms-time resolution and the ability to detect events with ∼100 Jy ms (7 σ ) fluence within the 55–85 MHz band. Furthermore, we incorporate an offline cross-correlation pipeline to improve positional accuracy of identified transients to within subarcminute levels. We present a full overview of the system design and initial testing results.}, archive = {J_ApJ}, author = {Nikita Kosogorov and Gregg Hallinan and Casey Law and Jack Hickish and Jayce Dowell and Marin M. Anderson and Judd D. Bowman and Ruby Byrne and Morgan Catha and Bin Chen and Sherry Chhabra and Larry D’Addario and Ivey Davis and Katherine Elder and Dale Gary and Charlie Harnach and Greg Hellbourg and Rick Hobbs and David Hodge and Mark Hodges and Yuping Huang and Andrea Isella and Daniel C. Jacobs and Ghislain Kemby and John T. Klinefelter and Matthew Kolopanis and James Lamb and Nivedita Mahesh and Surajit Mondal and Brian O’Donnell and Kathryn Plant and Corey Posner and Vinand Prayag and Andres Rizo and Andrew Romero-Wolf and Jun Shi and Greg Taylor and Mike Virgin and Akshatha Vydula and Sandy Weinreb and David Woody and Sijie Yu and Peijin Zhang and Yifan (Amy) Zhao}, doi = {10.3847/1538-4357/add014}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {265}, shortjournal = {The Astrophys. J.}, title = {Implementing continuous all-sky monitoring with the OVRO-LWA to identify prompt and precursor counterparts of gravitational wave events}, volume = {985}, year = {2025}, }
• (2025). Primordial non-gaussianity systematics from redshift mismatch with SPHEREx. ApJ, 985(2), 264. (www)

  @article{ , abstract = {The ability to differentiate between different models of inflation through the imprint of primordial non-Gaussianity (PNG) requires stringent constraints on the local PNG parameter {f}_{\rm{NL}\,}^{\,\rm{loc}} . Upcoming data from the large-scale structure surveys like Euclid, Vera C. Rubin Observatory, and the Spectro-Photometer for the History of the Universe, Epoch of Reionization, and Ices Explorer (SPHEREx) will be instrumental in advancing our understanding of the inflationary epoch. In this context, we present forecasts on PNG with tomographic angular power spectra derived from simulations of SPHEREx. We put forward the effects of redshift bin mismatch of galaxies as a significant source of systematic uncertainty in the estimation of both {f}_{\rm{NL}\,}^{\,\rm{loc}} and galaxy linear halo bias. We simulate 500 SPHEREx-like galaxy density fields and divide the galaxies into redshift bins assuming Gaussian photometric redshift errors. We show that the misclassification of galaxies in redshift bins can result in strong apparent tensions on {f}_{\rm{NL}\,}^{\,\rm{loc}} up to ∼3–6 σ and up to ∼9–12 σ on galaxy bias. To address this, we propose a scattering matrix formalism that mitigates bin mismatch of galaxies and enables unbiased estimation of cosmological parameters from tomographic angular clustering measurements.}, archive = {J_ApJ}, author = {Chandra Shekhar Saraf and David Parkinson}, doi = {10.3847/1538-4357/add1b8}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {264}, shortjournal = {The Astrophys. J.}, title = {Primordial non-gaussianity systematics from redshift mismatch with SPHEREx}, volume = {985}, year = {2025}, }
• (2025). Differentiable modeling of planet and substellar atmosphere: High-resolution emission, transmission, and reflection spectroscopy with ExoJAX2. ApJ, 985(2), 263. (www)

  @article{ , abstract = {Modeling based on differentiable programming holds great promise for astronomy, enabling advanced techniques such as gradient-based posterior sampling and optimization. This paradigm motivated us to develop ExoJAX , the first auto-differentiable spectrum model of exoplanets and brown dwarfs. ExoJAX directly calculates cross-sections as functions of temperature and pressure to minimize interpolation errors in high-dispersion spectra, although initial work focused on narrowband emission spectroscopy. Here, we introduce a fast, memory-efficient opacity algorithm and differentiable radiative transfer for emission, transmission, and reflection spectroscopy. In the era of data-rich JWST observations, retrieval analyses are often forced to bin high-resolution spectra due to computational bottlenecks. The new algorithm efficiently handles native-resolution data, preserving the full information content and dynamic range. The advances proposed in this paper enable broader applications, demonstrated by retrievals of GL 229B's high-dispersion emission, WASP-39 b's JWST mid-resolution transmission at original resolution ( R ∼ 2700), and Jupiter's reflection spectrum. We derive a C/O ratio for GL 229B consistent with its host star, constrain WASP-39 b's radial velocity from molecular line structures, and infer Jupiter's metallicity in line with previous estimates.}, archive = {J_ApJ}, author = {Hajime Kawahara and Yui Kawashima and Shotaro Tada and Hiroyuki Tako Ishikawa and Ko Hosokawa and Yui Kasagi and Takayuki Kotani and Kento Masuda and Stevanus K. Nugroho and Motohide Tamura and Hibiki Yama and Daniel Kitzmann and Nicolas Minesi and Brett M. Morris}, doi = {10.3847/1538-4357/adcba2}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {263}, shortjournal = {The Astrophys. J.}, title = {Differentiable modeling of planet and substellar atmosphere: High-resolution emission, transmission, and reflection spectroscopy with ExoJAX2}, volume = {985}, year = {2025}, }
• (2025). JWST/MIRI observations of newly formed dust in the cold, dense shell of the type IIn SN 2005ip. ApJ, 985(2), 262. (www)

  @article{ , abstract = {Dust from core-collapse supernovae (CCSNe), specifically Type IIP supernovae (SNe IIP), has been suggested to be a significant source of the dust observed in high-redshift galaxies. CCSNe eject large amounts of newly formed heavy elements, which can condense into dust grains in the cooling ejecta. However, infrared (IR) observations of typical CCSNe generally measure dust masses that are too small to account for the dust production needed at high redshifts. Type IIn SNe (SNe IIn), classified by their dense circumstellar medium, are also known to exhibit strong IR emission from warm dust, but the dust origin and heating mechanism have generally remained unconstrained because of limited observational capabilities in the mid-IR (MIR). Here, we present a JWST/MIRI Medium Resolution Spectrograph spectrum of the SN IIn SN 2005ip nearly 17 yr post-explosion. The SN IIn SN 2005ip is one of the longest-lasting and most well-studied SNe observed to date. Combined with a Spitzer MIR spectrum of SN 2005ip obtained in 2008, this data set provides a rare 15 yr baseline, allowing for a unique investigation of the evolution of dust. The JWST spectrum shows the emergence of an optically thin silicate dust component (≳0.08 M ⊙ ) that is either not present or more compact/optically thick in the earlier Spitzer spectrum. Our analysis shows that this dust is likely newly formed in the cold, dense shell (CDS), between the forward and reverse shocks, and was not preexisting at the time of the explosion. There is also a smaller mass of carbonaceous dust (≳0.005 M ⊙ ) in the ejecta. These observations provide new insights into the role of SN dust production, particularly within the CDS, and its potential contribution to the rapid dust enrichment of the early Universe.}, archive = {J_ApJ}, author = {Melissa Shahbandeh and Ori D. Fox and Tea Temim and Eli Dwek and Arkaprabha Sarangi and Nathan Smith and Luc Dessart and Bryony Nickson and Michael Engesser and Alexei V. Filippenko and Thomas G. Brink and WeiKang Zheng and Tamás Szalai and Joel Johansson and Armin Rest and Schuyler D. Van Dyk and Jennifer Andrews and Chris Ashall and Geoffrey C. Clayton and Ilse De Looze and James M. DerKacy and Michael Dulude and Ryan J. Foley and Suvi Gezari and Sebastian Gomez and Shireen Gonzaga and Siva Indukuri and Jacob Jencson and Mansi Kasliwal and Zachary G. Lane and Ryan Lau and David Law and Anthony Marston and Dan Milisavljevic and Richard O’Steen and Justin Pierel and Matthew Siebert and Michael Skrutskie and Lou Strolger and Samaporn Tinyanont and Qinan Wang and Brian Williams and Lin Xiao and Yi Yang and Szanna Zsíros}, doi = {10.3847/1538-4357/adce77}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {262}, shortjournal = {The Astrophys. J.}, title = {JWST/MIRI observations of newly formed dust in the cold, dense shell of the type IIn SN 2005ip}, volume = {985}, year = {2025}, }
• (2025). Unraveling the origins of gamma-ray burst X-ray plateaus through a study of X-ray flares. ApJ, 985(2), 261. (www)

  @article{ , abstract = {The X-ray light curves of gamma-ray bursts (GRBs) display complex features, including plateaus and flares, that challenge theoretical models. Here, we study the properties of flares that are observed in the early afterglow phase (up to a few thousand seconds). We split the sample into two groups: bursts with and without an X-ray plateau. We find that the distributions of flare properties are similar in each group; specifically, the peak time ( t pk ) of the flares and the ratio of the flare width to the flare peak time ( w / t pk ), which is found to be ≈1, regardless of the presence of a plateau. We discuss these results in view of the different theoretical models aimed at explaining the origin of the plateau. These results are difficult to explain by viewing angle effects or late-time energy injection, but do not contradict the idea that GRBs with X-ray plateaus have a low Lorentz factor, on the order of tens. For these GRBs, the dissipation processes that produce the flares naturally occur at smaller radii compared to GRBs with higher Lorentz factors, while the flares maintain a similar behavior. Our results therefore provide independent support for the idea that many GRBs have a Lorentz factor of a few tens rather than a few hundreds.}, archive = {J_ApJ}, author = {H. Dereli-Bégué and A. Pe’er and D. Bégué and F. Ryde}, doi = {10.3847/1538-4357/adcead}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {261}, shortjournal = {The Astrophys. J.}, title = {Unraveling the origins of gamma-ray burst X-ray plateaus through a study of X-ray flares}, volume = {985}, year = {2025}, }
• (2025). Revealing the accretion flow in m87*: Insights from faraday rotation. ApJ, 985(2), 260. (www)

  @article{ , abstract = {The Faraday rotation measure (RM) is a commonly used tool to trace electron number density and magnetic fields in hot accretion flows, particularly in low-luminosity accreting supermassive black holes. We focus on the nuclear region of M87, which was observed at 230 GHz (1.3 mm) by the Event Horizon Telescope in 2019. It remains unclear whether this emission originates from the accretion flow, the jet base, or both. To probe the presence of an accretion flow, we explore the scenario where the linearly polarized emission from the counter jet, visible at 43 GHz (7 mm), is Faraday-rotated by the accretion flow. We calculate theoretical predictions for counter-jet polarization using analytical and numerical models. In all cases, we find a Faraday-thick flow at 43 GHz (7 mm), with RM ∼ 10 6 rad m −2 , and a polarization angle that follows a linear relationship with wavelength squared, consistent with external Faraday rotation. The more realistic model, which includes turbulence and magnetic field fluctuations, predicts that the polarization pattern should be time-dependent, and that the counter-jet emission is depolarized due to Faraday depth fluctuations across the accretion flow. Despite the Faraday thick regime and strong depolarization, the linear relationship persists, enabling us to constrain the flow's physical properties. Comparing the counter-jet and forward-jet linear polarization states should enable detection of M87's accretion flow and provide lower limits on electron density, magnetic field strength, and mass accretion rate.}, archive = {J_ApJ}, author = {Constanza Echiburú-Trujillo and Jason Dexter}, doi = {10.3847/1538-4357/adcec1}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {260}, shortjournal = {The Astrophys. J.}, title = {Revealing the accretion flow in m87*: Insights from faraday rotation}, volume = {985}, year = {2025}, }
• (2025). Searching for compact obscured nuclei in compton-thick active galactic nuclei. ApJ, 985(2), 259. (www)

  @article{ , abstract = {Compact obscured nuclei (CONs) are heavily obscured infrared cores that have been found in local (ultra-)luminous infrared galaxies. They show bright emission from vibrationally excited rotational transitions of HCN, known as HCN-vib, and are thought to harbor Compton-thick (CT, N H ≥ 10 24 cm −2 ) active galactic nuclei (AGNs) or extreme compact starbursts. We explore the potential evolutionary link between CONs and CT-AGNs by searching for CONs in hard-X-ray-confirmed CT-AGNs from the Great Observatories All-sky LIRG Survey (GOALS). Here, we present new Atacama Large Millimeter/submillimeter Array Band 6 observations that targeted HCN-vib emission in four hard-X-ray-confirmed CT-AGNs. We analyze these objects together with literature HCN-vib measurements of five additional hard-X-ray-confirmed CT-AGNs from the GOALS sample. We do not detect any CONs in this combined sample of nine CT-AGNs. We then explore a proposed evolutionary sequence in which CONs evolve into X-ray-detectable CT-AGNs once outflows and feedback reduce the column densities of the enshrouding gas. We find, however, no evidence of well-developed dense molecular outflows in the observed CT-AGNs. While this could suggest that CT-AGNs are not universally linked to CONs, it could also be explained by a short duty cycle for molecular outflows.}, archive = {J_ApJ}, author = {Makoto A. Johnstone and George C. Privon and Loreto Barcos-Muñoz and A.S. Evans and S. Aalto and Lee Armus and Franz E. Bauer and L. Blecha and J. S. Gallagher and S. König and Claudio Ricci and Ezequiel Treister and Cosima Eibensteiner and Kimberly L. Emig and Kara N. Green and Devaky Kunneriath and Jaya Nagarajan-Swenson and Alejandro Saravia and Ilsang Yoon}, doi = {10.3847/1538-4357/adcecb}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {259}, shortjournal = {The Astrophys. J.}, title = {Searching for compact obscured nuclei in compton-thick active galactic nuclei}, volume = {985}, year = {2025}, }
• (2025). Modeling fast X-ray variability around an accreting black hole. ApJ, 985(2), 258. (www)

  @article{ , abstract = {X-ray interband time lags are observed during the outbursts of black hole X-ray binaries. Timing analysis of fast variability in low Fourier frequency bands shows that high-energy photons lag behind low-energy photons, a phenomenon referred to as hard lag. Conversely, in high Fourier frequency bands, low-energy photons lag behind high-energy photons, known as soft lag. This frequency-dependent lag spectrum suggests that the lags arise from different physical processes. Notably, a trend has been observed wherein the lags shift toward shorter timescales during the rising hard state, indicating an evolution in the inner accretion flow. In this study, we simulate these interband lags by conducting Monte Carlo simulations of the rapid variability within the geometry of a jet base corona. We consider both inward propagating accretion rate fluctuations and reverberation (light-crossing) delays in our simulations. We successfully reproduce both low-frequency hard lags and high-frequency soft lags in a self-consistent manner. We replicate the observed evolution of the frequency-dependent lag spectra by varying the geometrical scale of the corona and the viscous frequency of the disk. Finally, we discuss the potential of a spherical corona and emphasize that polarization observations from the Imaging X-ray Polarimetry Explorer and the enhanced X-ray Timing and Polarimetry mission will be crucial for distinguishing the corona's geometry in future studies.}, archive = {J_ApJ}, author = {Yejing Zhan and Bei You and Adam Ingram and Wenkang Jiang and Fayin Wang}, doi = {10.3847/1538-4357/adcf1d}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {258}, shortjournal = {The Astrophys. J.}, title = {Modeling fast X-ray variability around an accreting black hole}, volume = {985}, year = {2025}, }
• (2025). High-resolution observational features of type i solar radio bursts. ApJ, 985(2), 257. (www)

  @article{ , abstract = {In this paper, we statistically studied the characteristic features of solar radio Type I bursts observed by Chashan broadband solar radio spectrometer at meter wavelengths from 00:06 to 07:28 UT on 2023 December 13. Based on the image morphology, we develop a method to identify individual Type I bursts on the dynamic spectra from a connected region with a ratio of the duration to bandwidth less than or equal to 3.8 and the area sum (total pixels) greater than 4. In total, 102,073 and 78,773 bursts are detected on right-hand circular polarization and left-hand circular polarization components, respectively. We find Type I bursts with a mean lifetime of 0.7 s, a mean bandwidth of 5.6 MHz, and a relative bandwidth Δ f / f 0 of about 2%–3%. Consistent with the previous findings of hard X-ray pulses, microwave pulses, Type III bursts, and decimetric spikes, Type I bursts exhibit their duration, bandwidth, peak intensity, and area sum with a power-law distribution. From the linear fitting in log–log space, we obtain the slope index between 1 and 3.5 for various parameters. Meanwhile, Type I bursts display the mean polarization degree in the range from −22% to 33%, and different bursts have various degrees. We find that Type I bursts tend to appear as a chain, and the short periods of 0.92 and 1.22 s are detected in two burst chains. Our finding would be an observational constraint for the emission mechanism and physical model of solar Type I radio bursts.}, archive = {J_ApJ}, author = {Yuzhi Yang and Zongjun Ning and Yuxiang Song and Yijie Han and Xiaoyu Tang and Mingbao Gao and Hui Liu and Jingye Yan and Bing Wang and Shuwang Chang}, doi = {10.3847/1538-4357/add143}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {257}, shortjournal = {The Astrophys. J.}, title = {High-resolution observational features of type i solar radio bursts}, volume = {985}, year = {2025}, }
• (2025). Height-dependent slow magnetoacoustic wave amplitude and energy flux in sunspot atmospheres. ApJ, 985(2), 256. (www)

  @article{ , abstract = {Slow magnetoacoustic waves (SMAWs) have been considered a possible candidate for chromospheric heating in the past. This study analyzed 20 active regions observed between 2012 and 2016 to examine the amplitude and energy flux variation of SMAWs in the umbral atmosphere. Six different wavelength channels from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory, covering regions from the photosphere to the low corona, were utilized for this purpose. The wave amplitude estimations show a gradual increase in 3 minute oscillation amplitude, peaking between 700 and 900 km, followed by a steady decrease; further, at altitudes greater than 1800 km, it appears to increase and decrease again. The corresponding energy flux, on the other hand, displays a steady and monotonous decrease with a significant reduction in value from approximately 3.32 ± 0.50 kW m −2 near the photosphere to about 6.47 ± 3.16 × 10 −4 W m −2 at an altitude of 2585 km. This decay may be attributed to radiative damping and shock dissipation in the lower altitudes and thermal conduction and viscosity in the higher altitudes. The missing flux is a factor of 3–15 lower than that required to counterbalance the chromospheric radiative losses.}, archive = {J_ApJ}, author = {Y. Sanjay and S. Krishna Prasad and P. S. Rawat}, doi = {10.3847/1538-4357/add336}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {256}, shortjournal = {The Astrophys. J.}, title = {Height-dependent slow magnetoacoustic wave amplitude and energy flux in sunspot atmospheres}, volume = {985}, year = {2025}, }
• (2025). Three-dimensional orbit and dynamical masses of GJ 105 AC. ApJ, 985(2), 255. (www)

  @article{ , abstract = {The precision of stellar models is higher than the precision at which we are able to measure the masses of most stars, with the notable exception of binaries where we can determine dynamical masses of the component stars. In addition to well-measured stellar properties, the ideal benchmark star is far enough from its companion that its properties are indistinguishable from an otherwise identical single star. Currently, there are a handful of stars with precise (±3%), model-independent mass measurements that are "effectively single" and for which we can obtain clean spectra (i.e., spectra that are not blended with a close companion). In this paper, we introduce GJ 105 AC as the newest members of this exclusive population. We present an updated orbital analysis for the long-period K3+M7 binary GJ 105 AC. We jointly analyze radial velocity (RV) and relative astrometry data, including new RVs from the Miniature Exoplanet Radial Velocity Array that capture the full periapsis passage and the RV minimum of the 76.0 ± 1.3 yr orbit for the first time. We derive precise dynamical masses of M 1 = 0.78 ± 0.02 M ⊙ and M 2 = 0.098 ± 0.002 M ⊙ . We find that of all stars with similarly precise masses (∼2%), GJ 105 AC stands out as having the widest on-sky separation after α Centauri AB, making it one of the most easily accessible to spectroscopy, as well as the the second-widest true separation, ensuring that its members are truly "effectively single" in terms of their evolution.}, archive = {J_ApJ}, author = {Cayla M. Dedrick and Jason T. Wright and Jason D. Eastman and Cullen H. Blake and Samson A. Johnson and Peter Plavchan and John Asher Johnson and David H. Sliski and Maurice L. Wilson and Robert A. Wittenmyer and Thomas Barclay and Jonathan Horner and Stephen R. Kane and Sharon X. Wang}, doi = {10.3847/1538-4357/adc564}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {255}, shortjournal = {The Astrophys. J.}, title = {Three-dimensional orbit and dynamical masses of GJ 105 AC}, volume = {985}, year = {2025}, }
• (2025). Molecular evolution of H2O:O2 ices at different temperatures in simulated space environments. i. chemical kinetics and equilibrium. ApJ, 985(2), 254. (www)

  @article{ , abstract = {We computationally investigated the chemical evolution of H 2 O:O 2 ices (6:1 ratio) under irradiation by cosmic-ray analogs (0.8 MeV H + ) at 9, 50, and 100 K to understand the implications the chemical evolution of O 2 -containing ices in space, such as the surface of the Moon, comets, outer solar system bodies such Europa and Enceladus, as well as Kuiper Belt objects, and cold regions of the interstellar medium (ISM). Using experimental data and the PROCODA code with 200 reactions coupled equations involving 12 species, we calculated physicochemical parameters such as effective rate coefficients (ERCs), chemical abundances, and desorption. Six species were observed experimentally (H 2 O, O 2 , HO 2 , H 2 O 2 , O 3 , and HO 3 ), while six were predicted but not observed in the experiments (H, H 2 , H 3 , O, OH, and H 3 O). Our findings highlight the influence of temperature on chemical equilibria and desorption yields, with certain reaction rates diminishing at 50 K. Among the results were the lists with the ERCs, and the reaction branching ratio obtained by best-fit models can be employed in astrochemical models. Curiously, we observe that the average ERCs for bimolecular collisions decrease by half as the ice temperature increases, varying from 5.8e-25 to 2.9e-25 cm 3 molecules −1 s −1 for the ices studied. These results enhance our understanding of the physical chemistry of astrophysical ices under ionizing radiation, providing valuable data for astrochemical models that assess the effects of cosmic radiation on the composition and stability of icy bodies in the solar system and denser and colder regions of the ISM.}, archive = {J_ApJ}, author = {J. R. C. Silva and L. M. S. V. Queiroz and L. F. A. Ferrão and S. Pilling}, doi = {10.3847/1538-4357/adc924}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {254}, shortjournal = {The Astrophys. J.}, title = {Molecular evolution of H2O:O2 ices at different temperatures in simulated space environments. i. chemical kinetics and equilibrium}, volume = {985}, year = {2025}, }
• (2025). Exploring the mysterious high-ionization source powering [Ne v] in high-z analog SBS0335-052 e with JWST/MIRI. ApJ, 985(2), 253. (www)

  @article{ , abstract = {Nearby blue compact dwarf galaxies (BCDs) are considered analogs to objects from the Epoch of Reionization revealed by JWST, having similarly low stellar masses, low metallicities, and high specific star formation rates. Thus, they represent ideal local laboratories for detailed multiwavelength studies of their properties and mechanisms that shape them. We report the first JWST MIRI/MRS observations of the BCD SBS 0335-052 E, analyzing MIR emission lines tracing different levels of ionization (e.g., [Ne ii ], [S iv ], [Ne iii ], [O iv ], [Ne v ]) of the ionized gas. SBS 0335-052 E MIR emission is characterized by a bright point source, located in one of the youngest and most embedded stellar clusters ( t ∼ 3 Myr, A V ∼ 15), and underlying extended high-ionization emission (i.e., [O iv ] and [Ne v ]) from the surroundings of the older and less dusty stellar clusters ( t < 20 Myr, A V ∼ 8). From a comparison with state-of-the-art models, we can exclude shocks, X-ray binaries, and old stellar populations as the main sources of ionization. Interestingly, a 4%–8% contribution of a ∼10 5 M ⊙ intermediate massive black hole (IMBH) is needed to justify the strong [Ne v ]/[Ne ii ] and would be consistent with optical/UV line ratios from previous studies. However, even IMBH models cannot explain the strongest [O iv ]/[Ne iii ]. Also, star-forming models (regardless of including X-ray binaries) struggle to reproduce even the lower ionization line ratios (e.g., [S iv ]/[Ne ii ]) typically observed in BCDs. Overall, while current models suggest the need to account for an accreting IMBH in this high- z analog, limitations still exist in predicting high-ionization emission lines (I.P. > 54 eV) when modeling these low-metallicity environments, and thus other sources of ionization cannot be fully ruled out.}, archive = {J_ApJ}, author = {Matilde Mingozzi and Macarena Garcia del Valle-Espinosa and Bethan L. James and Ryan J. Rickards Vaught and Matthew Hayes and Ricardo O. Amorín and Claus Leitherer and Alessandra Aloisi and Leslie Hunt and David Law and Chris T. Richardson and Aidan Pidgeon and Karla Z. Arellano-Córdova and Danielle A. Berg and John Chisholm and Svea Hernandez and Logan Jones and Nimisha Kumari and Crystal L. Martin and Swara Ravindranath and Livia Vallini and Xinfeng Xu}, doi = {10.3847/1538-4357/adc996}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {253}, shortjournal = {The Astrophys. J.}, title = {Exploring the mysterious high-ionization source powering [Ne v] in high-z analog SBS0335-052 e with JWST/MIRI}, volume = {985}, year = {2025}, }
• (2025). Eccentric features in the gravitational-wave phase of dynamically formed black hole binaries. ApJ, 985(2), 252. (www)

  @article{ , abstract = {We study the gravitational-wave (GW) phase shift arising from center-of-mass accelerations of binary black hole (BBH) mergers formed dynamically in three-body systems, where both the inner orbit of the merging binary and the outer orbit are eccentric. We provide a semi-analytical model and several analytical approximations that allow for fast evaluation of both the temporal evolution and the maximum value of the phase shift. The highest phase shifts occur when the binary merges close to the pericenter of the outer orbit, and can in this case be orders of magnitude larger compared to the circular limit. At high outer-orbit eccentricities, the orbital curvature leaves distinct imprints on the phase shift if the binary passes the outer pericenter during its inspiral. By comparing with phase shifts measured in numerical chaotic three-body scatterings, we show that our model accurately describes the observed phase of dynamically assembled binary systems in realistic astrophysical scenarios, providing a way to directly determine their formation channel via single GW observations. Phase shifts produced in such environments may receive additional amplifications due to the tidal pull from the perturber on the BBH.}, archive = {J_ApJ}, author = {Kai Hendriks and Lorenz Zwick and Johan Samsing}, doi = {10.3847/1538-4357/adcb35}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {252}, shortjournal = {The Astrophys. J.}, title = {Eccentric features in the gravitational-wave phase of dynamically formed black hole binaries}, volume = {985}, year = {2025}, }
• (2025). Galactic isolated stellar-mass black holes with the magnetospheric spark gap as possible GeV–TeV gamma-ray unidentified sources. ApJ, 985(2), 251. (www)

  @article{ , abstract = {Billions of isolated stellar-mass black holes (IBHs) are thought to wander through the interstellar medium (ISM) in the Galaxy, yet only one has been detected. IBHs embedded in ISM would accrete gas via Bondi–Hoyle–Littleton accretion, and with efficient magnetic flux accumulation, the magnetosphere would be formed in the vicinity of IBHs. We explore the detectability of such IBHs through high-energy gamma-rays from spark gaps in their magnetospheres based on our recent numerical simulation. Spark gap gamma-rays can be bright at the GeV–TeV energies when IBHs are in the dense ISM. About 10 3 and 10 IBHs might be contained in unidentified objects of the Fermi Large Area Telescope and the High Energy Stereoscopic System, respectively. A future Galactic plane survey by the Cherenkov Telescope Array Observatory would lead to ∼10 2 detections. We also evaluate the combined gamma-ray emission of IBHs in the Galaxy and find that the IBHs may contribute to the Galactic diffuse gamma-rays. IBHs will emit optical and X-ray photons from their accretion disk as counterparts, potentially useful for identifying candidates.}, archive = {J_ApJ}, author = {Koki Kin and Riku Kuze and Shigeo S. Kimura}, doi = {10.3847/1538-4357/adcb3d}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {251}, shortjournal = {The Astrophys. J.}, title = {Galactic isolated stellar-mass black holes with the magnetospheric spark gap as possible GeV–TeV gamma-ray unidentified sources}, volume = {985}, year = {2025}, }
• (2025). Main-sequence turnoff stars as probes of the ancient galactic relic: Chemo-dynamical analysis of a pilot sample. ApJ, 985(2), 250. (www)

  @article{ , abstract = {The main-sequence turnoff (MSTO) stars well preserve the chemical properties where they were born, making them ideal tracers for studying the stellar population. We perform a detailed chemo-dynamical analysis on moderately metal-poor (−2.0 < [Fe/H] < −1.0) MSTO stars to explore the early accretion history of the Milky Way. Our sample includes four stars observed with high-resolution spectroscopy using ESPaDOnS at the Canada–France–Hawaii Telescope and 163 nearby MSTO stars selected from the SAGA database with high-resolution results. Within the action-angle spaces, we identified Gaia–Sausage–Enceladus (GSE, 35 objects), stars born in the Milky Way (in situ, 31 objects), and other substructures (21 objects). We find that both GSE and in situ stars present a similar Li plateau around A (Li) ∼ 2.17. GSE shows a clear α -knee feature in Mg at [Fe/H] ∼ −1.60 ± 0.06, while the α -elements of in situ stars remain nearly constant within this metallicity range. The iron-peak elements show little difference between GSE and in situ stars except for Zn and Ni, which decrease in GSE at [Fe/H] > −1.6, while they remain constant for in situ stars. Among heavy elements, GSE shows overall enhancement in Eu, with [Ba/Eu] increasing with the metallicity, while this ratio remains almost constant for in situ stars, suggesting the contribution of longer timescale sources to the s -process in GSE. Moreover, for the first time, we present the r -process abundance pattern for an extremely r -process enhanced ( r -II) GSE star, which appears consistent with the solar r -process pattern except for Pr. Further investigation of larger GSE samples using high-resolution spectra is required to explore the reason for the significantly higher Pr in the GSE r -II star.}, archive = {J_ApJ}, author = {Renjing Xie and Haining Li and Ruizhi Zhang and Yin Wu and Xiang-Xiang Xue and Gang Zhao and Shi-Lin Zhang and Xiao-Jin Xie}, doi = {10.3847/1538-4357/adcba6}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {250}, shortjournal = {The Astrophys. J.}, title = {Main-sequence turnoff stars as probes of the ancient galactic relic: Chemo-dynamical analysis of a pilot sample}, volume = {985}, year = {2025}, }
• (2025). Simultaneous observation of ion-scale wave packets with opposite polarizations and their implications on the generation region in the inner heliosphere. ApJ, 985(2), 249. (www)

  @article{ , abstract = {This paper reports a dispersion analysis of two wave packets simultaneously observed near the local proton gyrofrequency by the Parker Solar Probe. The observed wave event exhibits clear two-banded wave packets both propagating along the magnetic field, characterized by left-handed (L-mode) and right-handed (R-mode) polarizations simultaneously. By incorporating the Doppler shift effect into a linear dispersion analysis, we find two possible scenarios that explain these simultaneous opposite polarizations: (1) Two inherently L-mode waves in the plasma frame, propagate parallel and antiparallel to the solar wind velocity, with similar wave frequencies and wave numbers. The polarization of the antiparallel propagating wave reverses as it moves sunward in the plasma frame while still comoving with the solar wind in the stationary frame. This reversal manifests the polarization of the wave as an R-mode in the spacecraft frame. (2) Simultaneous L-mode and R-mode waves propagate parallel to the solar wind velocity, with different wave frequencies and wave numbers. Concurrent proton observations during the wave event reveal a dominant anisotropic ( {T}_{\perp }/{T}_{\parallel }\gt 1 ) core distribution with a drifting beam population. Estimation of the linear growth rate for both L-mode and R-mode waves suggests that both scenarios are plausible, indicating that the observation is near the wave-generation region. We explore the potential impact of these simultaneous waves on solar wind heating and scattering effects, hypothesizing that such waves might enhance efficiency compared to waves with a single wave packet, contingent upon the statistical significance of such waves.}, archive = {J_ApJ}, author = {Sung Jun Noh and Xiangrong Fu and Misa Cowee and Lan K. Jian and Dae-Young Lee and Fan Guo and Ilya Kuzichev and Jungjoon Seough and Daniel B. Reisenfeld and John T. Steinberg and Ruth M. Skoug and Roberto Livi and Jia Huang}, doi = {10.3847/1538-4357/adcd66}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {249}, shortjournal = {The Astrophys. J.}, title = {Simultaneous observation of ion-scale wave packets with opposite polarizations and their implications on the generation region in the inner heliosphere}, volume = {985}, year = {2025}, }
• (2025). SZ–X-ray surface brightness fluctuations in the SPT-XMM clusters. ApJ, 985(2), 248. (www)

  @article{ , abstract = {The hot plasma in galaxy clusters, the intracluster medium, is expected to be shaped by subsonic turbulent motions, which are key for heating, cooling, and transport mechanisms. The turbulent motions contribute to the nonthermal pressure, which, if not accounted for, consequently imparts a hydrostatic mass bias. Accessing information about turbulent motions is thus of major astrophysical and cosmological interest. Characteristics of turbulent motions can be indirectly accessed through surface brightness fluctuations. This study expands on our pilot investigations of surface brightness fluctuations in the Sunyaev–Zel'dovich and in X-ray data by examining, for the first time, a large sample of 60 clusters using both SPT-SZ and XMM-Newton data and spans the redshift range 0.2 < z < 1.5, thus constraining the respective pressure and density fluctuations within 0.6 R 500 . We deem density fluctuations to be of sufficient quality for 32 clusters, finding mild correlations between the peak of the amplitude spectra of density fluctuations and various dynamical parameters. We infer turbulent velocities from density fluctuations with an average Mach number {{ \mathcal M }}_{\,\rm{3D}\,}=0.52\pm 0.14 , in agreement with numerical simulations. For clusters with inferred turbulent Mach numbers from fluctuations in both pressure, {{ \mathcal M }}_{\,\rm{P}\,} , and density, {{ \mathcal M }}_{\rho } , we find broad agreement between {{ \mathcal M }}_{\,\rm{P}\,} and {{ \mathcal M }}_{\rho } . Our results suggest either a bimodal or a skewed unimodal Mach number distribution, with the majority of clusters being turbulence-dominated (subsonic) while the remainder are shock-dominated (supersonic).}, archive = {J_ApJ}, author = {Charles E. Romero and Massimo Gaspari and Gerrit Schellenberger and Bradford A. Benson and Lindsey E. Bleem and Esra Bulbul and William Forman and Ralph Kraft and Paul Nulsen and Christian L. Reichardt and Arnab Sarkar and Taweewat Somboonpanyakul and Yuanyuan Su}, doi = {10.3847/1538-4357/adcd74}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {248}, shortjournal = {The Astrophys. J.}, title = {SZ–X-ray surface brightness fluctuations in the SPT-XMM clusters}, volume = {985}, year = {2025}, }
• (2025). Pulsar coherent radio emission from solitons: Average emission properties. ApJ, 985(2), 247. (www)

  @article{ , abstract = {Observations have established that coherent radio emission from pulsars arises at a few hundred kilometers above the stellar surface. Recent polarization studies have further demonstrated that plasma instabilities are necessary for charge bunching that gives rise to coherent emission. The formation of charged solitons in the electron–positron plasma is the only known bunching mechanism that can be realized at these heights. More than five decades of observations have revealed a number of emission features that should emerge from any valid radio emission mechanism. We have carried out numerical calculations to find the features of average emission from curvature radiation due to charged solitons. The characteristic curvature radiation spectrum has been updated from the well-known one-dimensional dependence to a general two-dimensional form, and the contribution from each soliton along the observer's line of sight (LOS) has been added to reproduce the pulsar emission. The outflowing plasma is formed by sparking discharges above the stellar surface that are located within concentric rings resembling the core–cone emission beam, and uniform distribution of solitons along any LOS has been assumed. The observed effects of radius-to-frequency mapping, where the lower-frequency emission originates from higher altitudes, are seen in this setup. The power-law spectrum and relative steepening of the core spectra with respect to the cones also emerge. The estimated polarization position angle reflects the geometrical configuration of pulsars as expected. These studies demonstrate the efficacy of coherent curvature radiation from charged solitons to reproduce the average observational features of pulsars.}, archive = {J_ApJ}, author = {Rahul Basu and Dipanjan Mitra and George I. Melikidze and Krzysztof Maciesiak}, doi = {10.3847/1538-4357/adce7a}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {247}, shortjournal = {The Astrophys. J.}, title = {Pulsar coherent radio emission from solitons: Average emission properties}, volume = {985}, year = {2025}, }
• (2025). Effects of magnetic boundary layer on galactic cosmic rays during the heliopause crossing for voyager 2. ApJ, 985(2), 246. (www)

  @article{ , abstract = {Voyager 2 crossed the heliopause in 2018 and observed a small-amplitude modulation of galactic cosmic rays beyond the heliopause, within a boundary layer approximately 0.57 au thick. Prior to this, it detected a similar boundary layer for both the cosmic rays and the magnetic field, with a scale of about 0.82 au inside the heliopause. In this study, we investigate the modulation of cosmic rays near the heliopause using numerical simulations that account for magnetic boundary layers on both sides of the heliopause. Our results indicate that the boundary layer beyond the heliopause leads to a significant reduction in the parallel diffusion coefficient for the cosmic rays, compared to values further into interstellar space, thereby causing modulation of cosmic rays beyond the heliopause. Inside the heliopause, the boundary layer reduces the perpendicular diffusion coefficient and potentially increases the parallel diffusion coefficient, relative to regions deep inside the heliosphere. This results in a steady increase in intensities of cosmic rays until a sudden jump at the heliopause. Our findings confirm that the presence of the boundary layer near the heliopause is crucial for explaining the observations of cosmic rays made by Voyager 2.}, archive = {J_ApJ}, author = {Xiaocheng Guo and Yu Zeng and Chi Wang}, doi = {10.3847/1538-4357/adceb2}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {246}, shortjournal = {The Astrophys. J.}, title = {Effects of magnetic boundary layer on galactic cosmic rays during the heliopause crossing for voyager 2}, volume = {985}, year = {2025}, }
• (2025). X-ray and radio polarimetry of the neutron star low-mass X-ray binary 4U 1728–34. ApJ, 985(2), 245. (www)

  @article{ , abstract = {We report the first X-ray and radio polarimetric results of the neutron star (NS) low-mass X-raydis binary atoll-source 4U 1728−34 using the Imaging X-ray Polarimetry Explorer (IXPE) and Australia Telescope Compact Array. We discovered that the X-ray source was polarized at PD = 1.9% ± 1.0% (3 σ errors) with a polarization angle of PA = −41° ± 16° (3 σ errors). Simultaneous Neutron Star Interior Composition Explorer observations show that the source was in a relatively hard state, marking it as the first IXPE observation of an NS atoll source in the hard state. We do not detect any significant linear polarization in the radio band, with a 3 σ upper limit of 2% at 5.5 GHz and 1.8% at 9 GHz. Combining the radio data sets provides the deepest upper limits on the radio polarization at <1.5% on the linear and circular polarization (measured at 7.25 GHz). The X-ray polarimetric results suggest a source geometry with a Comptonization component possibly attributed to a boundary layer emission or BL emission reflected off the disk , consistent with the other NS atoll sources.}, archive = {J_ApJ}, author = {Unnati Kashyap and Thomas J. Maccarone and Thomas D. Russell and Mason Ng and Swati Ravi and Eliot C. Pattie and Herman L. Marshall}, doi = {10.3847/1538-4357/adceb9}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {245}, shortjournal = {The Astrophys. J.}, title = {X-ray and radio polarimetry of the neutron star low-mass X-ray binary 4U 1728–34}, volume = {985}, year = {2025}, }
• (2025). Density profiles of TNG 300 voids across cosmic time. ApJ, 985(2), 244. (www)

  @article{ , abstract = {We present radial density profiles, as traced by luminous galaxies and dark matter particles, for voids in 11 snapshots of the TNG 300 simulation. The snapshots span 11.65 Gyr of cosmic time, corresponding to the redshift range 0 ≤ z ≤ 3. Using the comoving galaxy fields, voids were identified via a well-tested, watershed transformation-based algorithm. Voids were defined to be underdense regions that are unlikely to have arisen from Poisson noise, resulting in the selection of ∼100–200 of the largest underdense regions in each snapshot. At all redshifts, the radial density profiles as traced by both the galaxies and the dark matter resemble inverse top-hat functions. However, details of the functions (particularly the underdensities of the innermost regions and the overdensities of the ridges) evolve considerably more for the dark matter density profiles than for the galaxy density profiles. At all redshifts, a linear relationship between the galaxy and dark matter density profiles exists, and the slope of the relationship is similar to the bias estimates for TNG 300 snapshots. Lastly, we identify distinct environments in which voids can exist, defining "void-in-void" and "void-in-cloud" populations (i.e., voids that reside in larger underdense or overdense regions, respectively), and we investigate ways in which the relative densities of dark matter and galaxies in the interiors and ridges of these structures vary as a function of void environment.}, archive = {J_ApJ}, author = {Olivia Curtis and Bryanne McDonough and Tereasa G. Brainerd}, doi = {10.3847/1538-4357/adcebf}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {244}, shortjournal = {The Astrophys. J.}, title = {Density profiles of TNG 300 voids across cosmic time}, volume = {985}, year = {2025}, }
• (2025). The ALMA-CRISTAL survey: Weak evidence for star-formation-driven outflows in z ∼ 5 main-sequence galaxies. ApJ, 985(2), 243. (www)

  @article{ , abstract = {There is a broad consensus from theory that stellar feedback in galaxies at high redshifts is essential to their evolution, alongside conflicting evidence in the observational literature about its prevalence and efficacy. To this end, we utilize deep, high-resolution [C II ] emission-line data taken as part of the [C II ] resolved interstellar medium (ISM) in star-forming galaxies with the Atacama Large Millimeter/submillimeter Array (CRISTAL) survey. Excluding sources with kinematic evidence for gravitational interactions, we perform a rigorous stacking analysis of the remaining 15 galaxies to search for broad emission features that are too weak to detect in the individual spectra, finding only weak evidence that a broad component is needed to explain the composite spectrum. Additionally, such evidence is mostly driven by CRISTAL-02, which is already known to exhibit strong outflows in multiple ISM phases. Interpreting modest residuals in the stack at v ∼ 300 km s −1 as an outflow, we derive a mass outflow rate of {\dot{M}}_{{\rm{out}}} = 26 ± 11 M ⊙ yr −1 and a cold outflow mass-loading factor of η m = 0.49 ± 0.20. This result holds for the subsample with the highest star formation rate surface density (Σ SFR > 1.93 M ⊙ yr −1 kpc −2 ), but no such broad component is present in the composite of the lower-star-formation-rate density subsample. Our results imply that the process of star-formation-driven feedback may already be in place in typical galaxies at z = 5, but on average are not strong enough to completely quench ongoing star formation.}, archive = {J_ApJ}, author = {Jack E. Birkin and Justin S. Spilker and Rodrigo Herrera-Camus and Rebecca L. Davies and Lilian L. Lee and Manuel Aravena and Roberto J. Assef and Loreto Barcos-Muñoz and Alberto Bolatto and Tanio Diaz-Santos and Andreas L. Faisst and Andrea Ferrara and Deanne B. Fisher and Jorge González-López and Ryota Ikeda and Kirsten Knudsen and Juno Li and Yuan Li and Ilse de Looze and Dieter Lutz and Ikki Mitsuhashi and Ana Posses and Monica Relaño and Manuel Solimano and Ken-ichi Tadaki and Vicente Villanueva}, doi = {10.3847/1538-4357/adced3}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {243}, shortjournal = {The Astrophys. J.}, title = {The ALMA-CRISTAL survey: Weak evidence for star-formation-driven outflows in z ∼ 5 main-sequence galaxies}, volume = {985}, year = {2025}, }
• (2025). Secular evolution of quasiperiodic eruptions. ApJ, 985(2), 242. (www)

  @article{ , abstract = {Quasiperiodic eruptions (QPEs) are intense, repeating soft X-ray bursts with recurrence times about a few hours to a few weeks from galactic nuclei. More and more analyses show that QPEs are the result of collisions between a stellar mass object (SMO; a stellar mass black hole or a main-sequence star) and an accretion disk around a supermassive black hole (SMBH) in galactic nuclei. In this work, we propose an osculating trajectory method for efficiently calculating secular evolution of extreme mass ratio inspirals (EMRIs) that are perturbed by an accretion disk. This method accelerates the calculation of EMRI orbital evolution by orders of magnitude and lays the foundation for analyzing long-term QPE observations. Applying this method to orbital analyses of GSN 069 and eRO-QPE2, the two most stable QPE sources, we find informative constraints on the SMBH mass, the radiation efficiency of QPEs, the SMO nature, the accretion disk surface density, and the accretion disk viscosity. Combining all the QPE sources available, we find the QPE EMRIs can be divided into two populations according to their orbital eccentricities, where the orbital periods and the SMBH masses in the low-eccentricity population follow a scaling relation of {T}_{{\rm{obt}}}\propto {M}_{\bullet }^{n} with n ≈ 0.8.}, archive = {J_ApJ}, author = {Cong Zhou and Yuhe Zeng and Zhen Pan}, doi = {10.3847/1538-4357/adcee2}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {242}, shortjournal = {The Astrophys. J.}, title = {Secular evolution of quasiperiodic eruptions}, volume = {985}, year = {2025}, }
• (2025). The BTSbot-nearby discovery of SN 2024jlf: Rapid, autonomous follow-up probes interaction in an 18.5 mpc type IIP supernova. ApJ, 985(2), 241. (www)

  @article{ , abstract = {We present observations of the Type IIP supernova (SN) SN 2024jlf, including spectroscopy beginning just 0.7 days (∼17 hr) after first light. Rapid follow-up was enabled by the new BTSbot-nearby program, which involves autonomously triggering target-of-opportunity requests for new transients in Zwicky Transient Facility data that are coincident with nearby ( D < 60 Mpc) galaxies and identified by the BTSbot machine learning model. Early photometry and nondetections shortly prior to first light show that SN 2024jlf initially brightened by >4 mag day −1 , quicker than ∼90% of Type II SNe. Early spectra reveal weak flash ionization features: narrow, short-lived (1.3 < τ [days] < 1.8) emission lines of H α , He ii , and C iv . Assuming a wind velocity of v w = 50 km s −1 , these properties indicate that the red supergiant progenitor exhibited enhanced mass loss in the last year before explosion. We constrain the mass-loss rate to 1{0}^{-4}\lt \dot{M}\,[{M}_{\odot }\,{\mathrm{yr}}^{-1}]\lt 1{0}^{-3} by matching observations to model grids from two independent radiative hydrodynamics codes. BTSbot-nearby automation minimizes spectroscopic follow-up latency, enabling the observation of ephemeral early-time phenomena exhibited by transients.}, archive = {J_ApJ}, author = {Nabeel Rehemtulla and W. V. Jacobson-Galán and Avinash Singh and Adam A. Miller and Charles D. Kilpatrick and K-Ryan Hinds and Chang Liu and Steve Schulze and Jesper Sollerman and Theophile Jegou du Laz and Tomás Ahumada and Katie Auchettl and S. J. Brennan and Michael W. Coughlin and Christoffer Fremling and Anjasha Gangopadhyay and Daniel A. Perley and Nikolaus Z. Prusinski and Josiah Purdum and Yu-Jing Qin and Sara Romagnoli and Jennifer Shi and Jacob L. Wise and Tracy X. Chen and Steven L. Groom and David O. Jones and Mansi M. Kasliwal and Roger Smith and Niharika Sravan and Shrinivas R. Kulkarni}, doi = {10.3847/1538-4357/adcf1e}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {241}, shortjournal = {The Astrophys. J.}, title = {The BTSbot-nearby discovery of SN 2024jlf: Rapid, autonomous follow-up probes interaction in an 18.5 mpc type IIP supernova}, volume = {985}, year = {2025}, }
• (2025). Evolution of the inner accretion flow and the white dwarf spin pulse during the 2023 outburst in GK persei. ApJ, 985(2), 240. (www)

  @article{ , abstract = {We present our X-ray and optical observations performed by NICER, NuSTAR, and Tomo-e Gozen during the 2023 outburst in the intermediate polar GK Persei. The X-ray spectrum consisted of three components: blackbody (BB) emission of several tens of eVs from the irradiated white dwarf (WD) surface, a source possibly including several emission lines around 1 keV, and multitemperature bremsstrahlung emission from the accretion column. The 351.3 s WD spin pulse was detected in X-rays, and the observable X-ray flux from the column drastically decreased at the off-pulse phase, which suggests that the absorption of the column by the accreting gas, called the curtain, was the major cause of the pulse. As the system became brighter in the optical, the column became fainter, the pulse amplitude became higher, and the energy dependence of pulses became weaker at <8 keV. These phenomena could be explained by the column's more pronounced absorption by the denser curtain as mass-accretion rates increased. The BB and line fluxes rapidly decreased at the optical decline, which suggests the expansion of the innermost disk edge with decreasing accretion rates. The electron scattering or the column geometry may be associated with the almost no energy dependence of high-energy pulses. The irradiated vertically thick structure at the disk may generate optical quasi-periodic oscillations with a period of ∼5700 s.}, archive = {J_ApJ}, author = {Mariko Kimura and Takayuki Hayashi and Yuuki Wada and Wataru Iwakiri and Shigeyuki Sako and Martina Veresvarska and Simone Scaringi and Noel Castro-Segura and Christian Knigge and Keith C. Gendreau and Zaven Arzoumanian}, doi = {10.3847/1538-4357/adcf27}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {240}, shortjournal = {The Astrophys. J.}, title = {Evolution of the inner accretion flow and the white dwarf spin pulse during the 2023 outburst in GK persei}, volume = {985}, year = {2025}, }
• (2025). Evidence of minijet emission in a large emission zone from a magnetically dominated gamma-ray burst jet. ApJ, 985(2), 239. (www)

  @article{ , abstract = {The second brightest gamma-ray burst (GRB) in history, GRB 230307A, provides an ideal laboratory to study the mechanism of GRB prompt emission thanks to its extraordinarily high photon statistics and its single-episode activity. Here we demonstrate that the rapidly variable components of its prompt emission compose an overall broad single pulse-like profile. Although these individual rapid components are aligned in time across all energy bands, this overall profile conspires to show a well-defined energy-dependent behavior that is typically seen in single GRB pulses. Such a feature demonstrates that the prompt emission of this burst is from many individual emitting units that are casually linked in a emission site at a large distance from the central engine. Such a scenario is in natural consistency with the internal-collision-induced magnetic reconnection and turbulence framework, which invokes many minijets due to local magnetic reconnection that constantly appear and disappear in a global magnetically dominated jet.}, archive = {J_ApJ}, author = {S.-X. Yi and C.-W. Wang and X. Shao and R. Moradi and H. Gao and B. Zhang and S.-L. Xiong and S.-N. Zhang and W.-J. Tan and J.-C. Liu and W.-C. Xue and Y.-Q. Zhang and C. Zheng and Y. Wang and P. Zhang and Z.-H. An and C. Cai and P.-Y. Feng and K. Gong and D.-Y. Guo and Y. Huang and B. Li and X.-B. Li and X.-Q. Li and X.-J. Liu and Y.-Q. Liu and X. Ma and W.-X. Peng and R. Qiao and L.-M. Song and J. Wang and P. Wang and X.-Y. Wen and S. Xiao and Y.-B. Xu and S. Yang and Q.-B. Yi and D.-L. Zhang and F. Zhang and H.-M. Zhang and J.-P. Zhang and Z. Zhang and X.-Y. Zhao and Y. Zhao and S.-J. Zheng}, doi = {10.3847/1538-4357/adcf98}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {239}, shortjournal = {The Astrophys. J.}, title = {Evidence of minijet emission in a large emission zone from a magnetically dominated gamma-ray burst jet}, volume = {985}, year = {2025}, }
• (2025). High-density symmetry energy: A key to the solution of the hyperon puzzle. ApJ, 985(2), 238. (www)

  @article{ , abstract = {The recently developed nuclear effective interaction based on the so-called N3LO Skyrme pseudopotential is extended to include hyperon–nucleon and hyperon–hyperon interactions by assuming similar density, momentum, and isospin dependence as for the nucleon–nucleon interaction. The parameters in these interactions are determined from either experimental information, if any, or chiral effective field theory or lattice quantum chromodynamics calculations of the hyperon potentials in nuclear matter around nuclear saturation density ρ 0 . We find that varying the high-density behavior of the symmetry energy E sym ( ρ ) can significantly change the critical density for hyperon appearance in neutron stars and thus the maximum mass M TOV of static hyperon stars. In particular, a symmetry energy that is soft around 2 ρ 0 –3 ρ 0 but stiff above about 4 ρ 0 can lead to M TOV ≳ 2 M ⊙ for hyperon stars and simultaneously be compatible with (1) the constraints on the equation of state of symmetric nuclear matter at suprasaturation densities obtained from flow data in heavy-ion collisions; (2) the microscopic calculations of the equation of state for pure neutron matter; (3) the tidal deformability of stars extracted from gravitational wave signal GW 170817; (4) the mass–radius relations of PSR J0030+0451, PSR J0740+6620, and PSR J0437-4715 measured from NICER; and (5) the observation of an unusually low mass and small radius in the central compact object of HESS J1731-347. Furthermore, the squared sound speed of the hyperon star matter naturally displays a strong peak structure around a baryon density of 3 ρ 0 –4 ρ 0 , consistent with a model-independent analysis of the multimessenger data. Our results suggest that the high-density symmetry energy could be a key to the solution of the hyperon puzzle in neutron star physics.}, archive = {J_ApJ}, author = {Jun-Ting Ye and Rui Wang and Si-Pei Wang and Lie-Wen Chen}, doi = {10.3847/1538-4357/add017}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {238}, shortjournal = {The Astrophys. J.}, title = {High-density symmetry energy: A key to the solution of the hyperon puzzle}, volume = {985}, year = {2025}, }
• (2025). Tracking an eruptive intermediate prominence originating from the farside of the sun. ApJ, 985(2), 237. (www)

  @article{ , abstract = {In this paper, we carry out multiwavelength and multiview observations of the eruption of an intermediate prominence originating from the farside of the Sun on 2023 March 12. The southeast footpoint of the prominence is located in NOAA Active Region 13252. The eruption generates a B7.8 class flare and a partial halo coronal mass ejection (CME). The prominence takes off at 02:00 UT and accelerates for nearly 3 hr. Rotation of the southeast leg of the prominence in the counterclockwise direction is revealed by spectroscopic and imaging observations. The apex of the prominence changes from a smooth loop to a cusp structure during the rising motion, and the northwest leg displays a drift motion after 04:30 UT, implying a writhing motion. Hence, the prominence eruption is most likely triggered by ideal kink instability. For the first time, we apply the Graduated Cylindrical Shell modeling in 3D reconstruction and tracking of the prominence for nearly 2 hr. Both the source region (110°E, 43°N) and northwest footpoint (162°E, 44°N) are located. The edge-on and face-on angular widths of the prominence are ∼6° and ∼86°, respectively. The axis has a tilt angle of ∼70° with the meridian. The heliocentric distance of the prominence leading edge increases from ∼1.26 R ⊙ to ∼2.27 R ⊙ . The true speed of the CME increases from ∼610 to ∼849 km s −1 .}, archive = {J_ApJ}, author = {Qingmin Zhang and Wenwei Pan and Beili Ying and Li Feng and Yiliang Li and Xiaoli Yan and Liheng Yang and Ye Qiu and Jun Chen and Suli Ma}, doi = {10.3847/1538-4357/add328}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {237}, shortjournal = {The Astrophys. J.}, title = {Tracking an eruptive intermediate prominence originating from the farside of the sun}, volume = {985}, year = {2025}, }
• (2025). Revealing the spectral properties of magnetic turbulence by synchrotron polarization gradients. ApJ, 985(2), 235. (www)

  @article{ , abstract = {Based on the modern understanding of MHD turbulence theory, we propose a new method for measuring the spectral properties of magnetic turbulence by synchrotron polarization gradient analysis. Using synthetic polarization observational data, we first confirm the feasibility of the gradient technique to determine the scaling properties of magnetic turbulence. We then apply this technique to the Galactic plane survey data from the Australia Telescope Compact Array and obtain the power-law spectral feature of the Galactic magnetic turbulence of E ∝ k −10/3 . Gradient techniques open up a new way to obtain spectral properties of magnetic turbulence from polarization observations, such as the Low-Frequency Array for Radio Astronomy, in the presence of low-frequency and strong Faraday depolarization.}, archive = {J_ApJ}, author = {Jian-Fu Zhang and Zi-Qi Liu}, doi = {10.3847/1538-4357/add5f2}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {235}, shortjournal = {The Astrophys. J.}, title = {Revealing the spectral properties of magnetic turbulence by synchrotron polarization gradients}, volume = {985}, year = {2025}, }
• (2025). R-process nucleosynthesis and radioactively powered transients from magnetar giant flares. ApJ, 985(2), 234. (www)

  @article{ , abstract = {We present nucleosynthesis and light-curve predictions for a new site of the rapid neutron capture process ( r -process) from magnetar giant flares (GFs). Motivated by observations indicating baryon ejecta from GFs, J. Cehula et al. proposed that mass ejection occurs after a shock is driven into the magnetar crust during the GF. We confirm using nuclear reaction network calculations that these ejecta synthesize moderate yields of third-peak r -process nuclei and more substantial yields of lighter r -nuclei, while leaving a sizable abundance of free neutrons in the outermost fastest expanding ejecta layers. The final r -process mass fraction and distribution are sensitive to the relative efficiencies of α -capture and n -capture freeze-outs. We use our nucleosynthesis output in a semianalytic model to predict the light curves of novae breves, the transients following GFs powered by radioactive decay. For a baryonic ejecta mass similar to that inferred of the 2004 Galactic GF from SGR 1806-20, we predict a peak UV/optical luminosity of ∼10 39 –10 40 erg s −1 at ∼10–15 minutes, rendering such events potentially detectable to several Mpc following a gamma-ray trigger by wide-field transient monitors such as ULTRASAT/UVEX. The peak luminosity and timescale of the transient increase with the GF strength due to the larger ejecta mass. Although GFs likely contribute 1%–10% of the total Galactic r -process budget, their short delay-times relative to star formation make them an attractive source to enrich the earliest generations of stars.}, archive = {J_ApJ}, author = {Anirudh Patel and Brian D. Metzger and Jared A. Goldberg and Jakub Cehula and Todd A. Thompson and Mathieu Renzo}, doi = {10.3847/1538-4357/adceb7}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {234}, shortjournal = {The Astrophys. J.}, title = {R-process nucleosynthesis and radioactively powered transients from magnetar giant flares}, volume = {985}, year = {2025}, }
• (2025). Quantifying the limits of TESS stellar rotation measurements with the k2-TESS overlap. ApJ, 985(2), 233. (www)

  @article{ , abstract = {The Transiting Exoplanet Survey Satellite (TESS) has provided stellar rotation periods across much of the sky through high-precision light curves, but the reliability and completeness of these measurements require careful evaluation. We assess the accuracy of TESS-derived rotation periods by leveraging a cross-matched sample of ∼23,000 stars observed by both TESS and the K2 mission, treating K2 periods as a benchmark. Using causal pixel models to extract light curves and a Lomb–Scargle (LS) periodogram to identify rotation signals, we quantify the empirical uncertainties, reliability, and completeness of TESS rotation period measurements. We find that uncertainties on TESS-derived rotation periods are typically below 3% for stars with periods <10 days. Rotation periods are generally reliable out to 10 days, with ≳80% of measurements matching the K2 benchmark. Completeness and reliability drop dramatically for periods beyond ≃12 days due to the 27 day sector limitation. Stricter cuts on TESS magnitude and LS power improve reliability; the highest LS power tested (>0.2) ensures >90% reliability below 10 days but removes over half of potential detections. Stitching consecutive-sector light curves reduces period uncertainties but does not improve overall reliability or completeness due to persistent systematics. Our findings and code provide a framework for interpreting TESS-derived rotation periods and inform the selection of quality cuts to optimize studies of stellar rotation, young associations, and gyrochronology.}, archive = {J_ApJ}, author = {Andrew W. Boyle and Andrew W. Mann and Jonathan Bush}, doi = {10.3847/1538-4357/adcecc}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {233}, shortjournal = {The Astrophys. J.}, title = {Quantifying the limits of TESS stellar rotation measurements with the k2-TESS overlap}, volume = {985}, year = {2025}, }
• (2025). The kinematic signature of the warp and waves in the milky way disk. ApJ, 985(2), 232. (www)

  @article{ , abstract = {Using over 170,000 red clump (RC) stars selected from LAMOST and APOGEE, we conduct a detailed analysis of the stellar V Z as a function of L Z (or R g ) across different ϕ bins for various disk populations. The V Z of the whole RC sample stars exhibits a wavelike pattern superimposed on an exponentially increasing trend, indicating the contribution from disk warp, disk flare, and disk waves. Our results across various populations suggest that the thin disk is similar to the whole RC sample behavior, while the thick disk displays a wavelike pattern superimposed on a linearly increasing trend, meaning that the features of disk warp and waves are present in both thin and thick disks, and the disk flare feature is only present in the thin disk. These results indicate that the disk warp is potentially driven by secular processes like disk perturbations from intergalactic magnetic fields and a misaligned dark halo. The line-of-node of the disk warp of various populations displays a slight difference, with ϕ 0 = 5 \mathop{.}\limits^{\circ } 68 ± 2 \mathop{.}\limits^{\circ } 91 for the whole RC sample of stars, ϕ 0 = 5 \mathop{.}\limits^{\circ } 78 ± 2 \mathop{.}\limits^{\circ } 89 for the thin disk stars, and ϕ 0 = 4 \mathop{.}\limits^{\circ } 10 ± 3 \mathop{.}\limits^{\circ } 43 for the thick disk stars.}, archive = {J_ApJ}, author = {Weixiang Sun and Han Shen and Biwei Jiang and Xiaowei Liu}, doi = {10.3847/1538-4357/add141}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {232}, shortjournal = {The Astrophys. J.}, title = {The kinematic signature of the warp and waves in the milky way disk}, volume = {985}, year = {2025}, }
• (2025). Anisotropic particle acceleration in alfvénic turbulence. ApJ, 985(2), 231. (www)

  @article{ , abstract = {Alfvénic turbulence is an effective mechanism for particle acceleration in strongly magnetized, relativistic plasma. In this study, we investigate a scenario where turbulent plasma is influenced by a strong guide magnetic field, resulting in highly anisotropic turbulent fluctuations. In such cases, the magnetic moments of particles are conserved, which means that acceleration can only occur along the direction of the magnetic field. Consistent with previous analytic studies, we find through particle-in-cell simulations of magnetically dominated pair plasma that the momenta of accelerated particles are closely aligned with the magnetic field lines. Notably, the alignment angle decreases as particle energy increases, potentially limited only by the inherent curvature and gradients of the turbulent magnetic fluctuations. This finding has significant implications for interpreting the synchrotron radiation emitted by highly accelerated particles.}, archive = {J_ApJ}, author = {Cristian Vega and Stanislav Boldyrev and Vadim Roytershteyn}, doi = {10.3847/1538-4357/add147}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {231}, shortjournal = {The Astrophys. J.}, title = {Anisotropic particle acceleration in alfvénic turbulence}, volume = {985}, year = {2025}, }
• (2025). Evidence for Core–Core collision in barnard 68. ApJ, 985(2), 230. (www)

  @article{ , abstract = {The prestellar core Barnard 68 (B68) is a prototypical source to study the initial conditions and chemical processes of star formation. A previous numerical simulation suggested the southeastern bullet is impacting on the main body of B68. In order to obtain more observational evidence, mapping observations of the ground state SO (1 0 –0 1 ) emission line at 30 GHz were made with the Effelsberg 100 m telescope. Based on the velocity field and channel maps derived from SO, three velocity components were clearly detected. The velocity field of the main body indicates rotation and is well fitted by a solid-body rotation model. The measured radial velocity difference between the bullet and the main core is about 0.4 km s −1 , which is almost equal to the velocity obtained by the previous numerical simulation. Therefore, the bullet is most likely impacting on the rotating main body of B68. A 1D spherical non–local thermodynamic equilibrium Monte Carlo radiation transfer RATRAN code is performed to derive the radial abundance profile of SO by analyzing the observed velocity-integrated intensity. SO is depleted inside a 60'' (0.02 pc) radius from the core. The abundance stays constant at 2.0 × 10 −9 for radii larger than 60'' from the center of the main core. The abundance is enhanced at the interface of the bullet and the main core, indicating that shock waves were produced by the collision between the bullet and the main core. In conclusion, based on the kinematical and chemical analysis, our observational results support the previously proposed core–core collision scenario in B68.}, archive = {J_ApJ}, author = {Dalei Li and Christian Henkel and Alexander Kraus and Xindi Tang and Willem Baan and Jarken Esimbek and Ke Wang and Gang Wu and Tie Liu and Andrej M. Sobolev and Jianjun Zhou and Yuxin He and Toktarkhan Komesh}, doi = {10.3847/1538-4357/add326}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {230}, shortjournal = {The Astrophys. J.}, title = {Evidence for Core–Core collision in barnard 68}, volume = {985}, year = {2025}, }
• (2025). First polarimetric view of GX 349+2 with the imaging X-ray polarimetry explorer. ApJ, 985(2), 229. (www)

  @article{ , abstract = {We conducted a spectropolarimetric study of the bright Z source GX 349+2 using the Imaging X-ray Polarimetry Explorer (IXPE) observation. Our findings reveal a significant polarization degree (PD) of 1.1% ± 0.3% in the 2.0–8.0 keV energy range. Spectropolarimetric analysis was performed by modeling the source spectra with an absorbed multicolor disk component and a blackbody. This allowed us to constrain the polarization contributions from the disk and boundary/spreading layer. The results indicate that the observed polarization signal primarily originates from the disk and the spreading layer at the neutron star's surface, rather than the boundary layer. Additionally, we detect an excess polarization component, which we attribute to either an outflow or reflection processes within the system, indicating the presence of a third component, albeit not observed in the IXPE spectra. Furthermore, energy-resolved polarization analysis in the 2.0–4.0 and 4.0–8.0 keV energy ranges hinted at a marginal increase of PD with energy and rotation of polarization angle (PA). This also pointed to an energy-dependent dominance of emission and indicated that the variation in PA with energy (∼17 ∘ in the 2.0–4.0 keV energy range and ∼48 ∘ in the 4.0–8.0 keV energy range) is likely associated with the different nonorthogonal PAs of the disk and spreading layer components, which peak at different energies.}, archive = {J_ApJ}, author = {S. Lavanya and L. Giridharan and Neal Titus Thomas and Khushi Jirawala and M. Varun and S. B. Gudennavar and S. G. Bubbly}, doi = {10.3847/1538-4357/add330}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {229}, shortjournal = {The Astrophys. J.}, title = {First polarimetric view of GX 349+2 with the imaging X-ray polarimetry explorer}, volume = {985}, year = {2025}, }
• (2025). The RESOLVE and ECO g3 initiative: Drivers of h i content and X-ray emission in galaxy groups. ApJ, 985(2), 228. (www)

  @article{ , abstract = {Adding to the RESOLVE and ECO Gas in Galaxy Groups (G3) initiative, we examine possible drivers of group-integrated H i -to-halo mass ratios ( M HI,grp / M halo ) and group X-ray emission, including group halo mass ( M halo ), virialization as probed by crossing time ( t cross ), presence of active galactic nuclei (AGN), and group-integrated fractional stellar mass growth rate (FSMGR grp ). G3 groups span M halo = 10 11 −10 14.5 M ⊙ with comprehensive H i gas and AGN information, which we combine with X-ray stacking of ROSAT All-Sky data. We detect hot gas emission exceeding AGN and X-ray binary backgrounds confidently for M halo = 10 12.6 −10 14 M ⊙ and unambiguously for M halo > 10 14 M ⊙ , reflecting an inverse dependence of M HI,grp / M halo and hot gas emission on halo mass. At fixed halo mass, M HI,grp / M halo transitions to greater spread below t cross ∼ 2 Gyr. Dividing groups across this transition, lower- t cross groups show elevated X-ray emission compared to higher- t cross groups for M halo > 10 13.3 M ⊙ , but this trend reverses for M halo = 10 12.6 −10 13.3 M ⊙ . Additionally, AGN-hosting halos below M halo ∼ 10 12.1 M ⊙ exhibit a broad, ∼0.25 dex deep valley in M HI,grp / M halo compared to non-AGN-hosting halos with correspondingly reduced FSMGR grp . When diluted by non-AGN-hosting halos, this valley becomes shallower and narrower, falling roughly between {M}_{{\rm{halo}}}={10}^{11.5}\,{M}_{\odot } and {M}_{{\rm{halo}}}={10}^{12.1}\,{M}_{\odot } in the overall M HI,grp / M halo vs. M halo relation. We may also detect a second, less easily interpreted valley at M halo ∼ 10 13 M ⊙ . Neither valley matches theoretical predictions of a deeper valley located at or above {M}_{{\rm{halo}}}={10}^{12.1}\,{M}_{\odot } .}, archive = {J_ApJ}, author = {Zackary L. Hutchens and Sheila J. Kannappan and Kelley M. Hess and Andrew J. Baker and Ming Sun and Derrick S. Carr and Kathleen D. Eckert and David V. Stark}, doi = {10.3847/1538-4357/adc395}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {228}, shortjournal = {The Astrophys. J.}, title = {The RESOLVE and ECO g3 initiative: Drivers of h i content and X-ray emission in galaxy groups}, volume = {985}, year = {2025}, }
• (2025). A holistic exploration of the potentially recoverable redshift information of stage IV galaxy surveys. ApJ, 985(2), 227. (www)

  @article{ , abstract = {Extragalactic science and cosmology with Stage IV galaxy surveys will rely almost exclusively on redshift measurements derived solely from photometry, which are subject to systematic and statistical uncertainties with numerous analysis choices. Single-survey photometric redshift estimates ought to be improved by combining data from multiple surveys, with common wisdom asserting that optical data benefits from additional infrared (IR) but not ultraviolet (UV) coverage. The degree of improvement for either is not well characterized, and attempts necessitate assumptions of a chosen estimator and its prior information. We apply an information-theoretic metric of potentially recoverable redshift information to assess the impact of multi-survey photometry without assuming an estimator or priors in the context of the Vera C. Rubin Observatory Legacy Survey of Space and Time ( lsst ) in the optical, Roman and Euclid ( roman and euclid ) in the IR, and Cosmological Advanced Survey Telescope for Optical-UV Research ( c astor ) in the UV. Our approach uses mock catalogs to approximate conditional relationships between color and redshift from real samples, but is otherwise independent of estimator and prior information. We conclude that adding UV photometry can benefit redshift determination of certain galaxy populations, but that gain is tempered by their decreased chance of meeting detection criteria at higher wavelengths. We explore the spectral energy distributions of galaxies whose potentially recoverable redshift information is most impacted by additional photometry. The holistic assessment approach we develop here is generic and may be applied to quantify the impact of combining photometric data sets, changing experimental design, optimizing observing strategy, and mitigating systematics.}, archive = {J_ApJ}, author = {Bryan R. Scott and Alex I. Malz and Robert Sorba}, doi = {10.3847/1538-4357/adc995}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {227}, shortjournal = {The Astrophys. J.}, title = {A holistic exploration of the potentially recoverable redshift information of stage IV galaxy surveys}, volume = {985}, year = {2025}, }
• (2025). A multiwavelength study of the dynamic environment surrounding the FUor v960 mon. ApJ, 985(2), 226. (www)

  @article{ , abstract = {The evolution of young stars and planet-forming environments is intrinsically linked to their nascent surroundings. This is particularly evident for FU Orionis (FUor) objects—a class of young protostars known for dramatic outbursts resulting in significant increases in brightness. We present a case study of V960 Mon, an FUor that has recently been found to show signs of a fragmenting spiral arm, potentially connected to planet formation. Our study explores the large-scale environment (10 3 –10 4 au) and incorporates Atacama Large Millimeter/submillimeter Array band 3, band 4, and band 6 continuum data, molecular emissions from 12 CO, 13 CO, C 18 O, SiO, DCO + , N 2 D + , and DCN, alongside optical and near-infrared observations from Very Large Telescope (VLT) Multi Unit Spectroscopic Explorer (MUSE) and VLT Spectro-Polarimetric High-contrast Exoplanet REsearch instrument (SPHERE). We map a region of 20'' across where we find tantalizing emissions that provide a unique view of a young group of protostars, including the discovery of a class-0 protostar to the east of the FUor. The 12 CO and SiO tracers suggest that this object is at the base of an outflow, potentially impacting the surrounding medium. The MUSE and SPHERE observations indicate the presence of an elongated feature towards a prominent source to the southeast that may represent interaction between V960 Mon and its surroundings. Moreover, the C 18 O emission overlaps with the clumps of the detected fragmenting spiral arm. These findings provide the strongest evidence to date for a connection between infalling material, fragmentation, and the intensity outburst of a protostar. Our case study highlights the complex interactions between young stars and their surroundings that drive the evolution of the planet forming environment.}, archive = {J_ApJ}, author = {Philipp Weber and Silvio Ulloa and Sebastián Pérez and James Miley and Lucas Cieza and Sergei Nayakshin and Alice Zurlo and Hauyu Baobab Liu and Fernando Cruz-Sáenz de Miera and Antonio Hales and Antonio Garufi and Dimitris Stamatellos and Ágnes Kóspál and Viviana Guzmán}, doi = {10.3847/1538-4357/adc9a2}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {226}, shortjournal = {The Astrophys. J.}, title = {A multiwavelength study of the dynamic environment surrounding the FUor v960 mon}, volume = {985}, year = {2025}, }
• (2025). Unveiling two deeply embedded young protostars in the S68N class 0 protostellar core with JWST/NIRSpec. ApJ, 985(2), 225. (www)

  @article{ , abstract = {The near-infrared (NIR) emission of the youngest protostars still needs to be characterized to better understand the evolution of their accretion and ejection activity. We analyze James Webb Space Telescope NIRSpec 1.7–5.3 μ m observations of two deeply embedded sources in the S68N protostellar core in Serpens. The North Central source exhibits a highly obscured spectrum ( A K ∼ 4.8 mag) that is modeled with a pre-main-sequence photosphere and a hot disk component. The photospheric parameters are consistent with a young, low-mass photosphere, as suggested by the low surface gravity, log g of 1.95 ±0.15 cm s −2 . The hot disk suggests that accretion onto the central protostellar embryo is ongoing, although prototypical accretion-tracing emission lines H i are not detected. The South Central source, which is even more embedded ( A K ∼ 8 mag; no continuum is detected shortward of 3.6 μ m) appears to be driving the large-scale S68N protostellar outflow, and launches a collimated hot molecular jet detected in H 2 and CO rovibrational lines. Shock modeling of the H 2 (ro)vibrational lines establishes that fast C -type shocks (≥30 km s −1 ), with high pre-shock density (≥10 7 cm −3 ), and strong magnetic field ( b ∼ 3–10, where B=b\,\times \,\sqrt{{n}_{{\rm{H}}}({\mathrm{cm}}^{-3})}\,\mu {\rm{G}} ) best match the data. The bright CO fundamental line forest suggests energetic excitation, with the contribution of non-LTE effects, i.e., irradiation pumping. Detected OH and CH + rovibrational lines support this hypothesis. These two Class 0 protostars seem to be in very young evolutionary stages and still have to acquire the bulk of their final stellar masses. These results demonstrate that JWST enables unprecedented diagnostics of these first stages of the protostellar evolutionary phase.}, archive = {J_ApJ}, author = {Valentin J. M. Le Gouellec and Ben W. P. Lew and Thomas P. Greene and Doug Johnstone and Antoine Gusdorf and Logan Francis and Curtis DeWitt and Michael Meyer and Łukasz Tychoniec and Ewine F. van Dishoeck and Mary Barsony and Klaus W. Hodapp and Peter G. Martin and Massimo Robberto}, doi = {10.3847/1538-4357/adcac4}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {225}, shortjournal = {The Astrophys. J.}, title = {Unveiling two deeply embedded young protostars in the S68N class 0 protostellar core with JWST/NIRSpec}, volume = {985}, year = {2025}, }
• (2025). Coordinated space- and ground-based monitoring of accretion bursts in a protoplanetary disk: Establishing mid-infrared hydrogen lines as accretion diagnostics for JWST/MIRI. ApJ, 985(2), 224. (www)

  @article{ , abstract = {In this paper, we establish and calibrate mid-infrared (MIR) hydrogen recombination lines observed with the James Webb Space Telescope as accretion tracers for pre-main-sequence stars that accrete from circumstellar disks. This work is part of a coordinated, multi-observatory effort that monitored the well-known binary system DQ Tau over three orbital periods, capturing its periodic accretion bursts. In this first paper, we present nine epochs of Mid-Infrared Instrument (MIRI) Medium Resolution Spectrometer (MRS) spectra with near-simultaneous Las Cumbres Observatories (LCO) photometry and Very Large Telescope X-shooter spectroscopy. This program caught exceptional accretion variability, spanning almost 2 orders of magnitude between the peak of the first periastron accretion burst and the following quiescent phases. The MIRI spectra show H i line luminosities that vary in step with the accretion-luminosity time series measured with LCO and X-shooter. The tight correlation with accretion and the large line widths, which MIRI resolves for the first time, support an accretion-flow origin for MIR H i transitions. Combining these three exceptional data sets, we derive accurate relations between MIR line and accretion luminosities for three H i transitions (10–7, 7–6, and 8–7), and improve upon a previous relation based on Spitzer spectra. These new relations equip the community with a direct measurement of the accretion luminosity from MIRI-MRS spectra. A MIRI-derived accretion luminosity is fundamental for time-domain chemistry studies, as well as for studies of accretion in embedded/distant sources that are currently inaccessible in the optical. With these new relations, we provide accretion luminosities for an archival sample of 38 MRS spectra of protoplanetary disks published to date.}, archive = {J_ApJ}, author = {Benjamin M. Tofflemire and Carlo F. Manara and Andrea Banzatti and Klaus M. Pontoppidan and Joan Najita and Brunella Nisini and Emma T. Whelan and Justyn Campbell-White and Hala Alqubelat and Adam L. Kraus and Christian Rab and Adrien Houge and Sebastiaan Krijt and James Muzerolle and Eleonora Fiorellino and Myriam Benisty and Lukasz Tychoniec and Colette Salyk and Guillaume Bourdarot and Jacob Hyden}, doi = {10.3847/1538-4357/adcc23}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {224}, shortjournal = {The Astrophys. J.}, title = {Coordinated space- and ground-based monitoring of accretion bursts in a protoplanetary disk: Establishing mid-infrared hydrogen lines as accretion diagnostics for JWST/MIRI}, volume = {985}, year = {2025}, }
• (2025). A large-scale search for photometrically variable active galactic nuclei in dwarf galaxies using the young supernova experiment. ApJ, 985(2), 223. (www)

  @article{ , abstract = {We conduct an analysis of over 60,000 dwarf galaxies ( 7\lesssim {\mathrm{log}}\,{M}_{* }/{M}_{\odot }\lesssim 10 ) in search of photometric variability indicative of active galactic nuclei (AGNs). Using data from the Young Supernova Experiment, a time domain survey on the Pan-STARRS telescopes, we construct light curves for each galaxy in up to four bands ( griz ) where available. We select objects with AGN-like variability by fitting each light curve with a damped random walk (DRW) model. After quality cuts and removing transient contaminants, we identify 1100 variability-selected AGN candidates (representing 2.4% of the available sample). We analyze their spectra to measure various emission lines and calculate black hole (BH) masses, finding general agreement with previously found mass scaling relations and nine potential intermediate-mass BH candidates. Furthermore, we reanalyze the light curves of our candidates to calculate the dampening timescale τ DRW associated with the DRW and see a similar correlation between this value and the BH mass. Finally, we estimate the active fraction as a function of stellar mass and see evidence that the active fraction increases with host mass.}, archive = {J_ApJ}, author = {Alexander Messick and Vivienne Baldassare and David O. Jones and K. Decker French and Sandra I. Raimundo and Nicholas Earl and Katie Auchettl and David A. Coulter and Mark E. Huber and Margaret E. Verrico and Thomas de Boer and Kenneth C. Chambers and Hua Gao and Chien-Cheng Lin and Richard J. Wainscoat}, doi = {10.3847/1538-4357/adcdff}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {223}, shortjournal = {The Astrophys. J.}, title = {A large-scale search for photometrically variable active galactic nuclei in dwarf galaxies using the young supernova experiment}, volume = {985}, year = {2025}, }
• (2025). The JCMT BISTRO-3 survey: Variation of magnetic field orientations on parsec and subparsec scales in the massive star-forming region g28.34+0.06. ApJ, 985(2), 222. (www)

  @article{ , abstract = {Magnetic fields play a significant role in star-forming processes on core to clump scales. We investigate magnetic field orientations and strengths in the massive star-forming clump P2 within the filamentary infrared dark cloud G28.34+0.06 using dust polarization observations made using SCUBA-2/POL-2 on the James Clerk Maxwell Telescope (JCMT) as part of the B-field In STar-forming Region Observations (or BISTRO) survey. We compare the magnetic field orientations at the clump scale of ∼2 pc from these JCMT observations with those at the core scale of ∼0.2 pc from archival Atacama Large Millimeter/submillimeter Array data, finding that the magnetic field orientations on these two different scales are perpendicular to one another. We estimate the distribution of magnetic field strengths, which range from 50 to 430 μ G over the clump. The region forming the core shows the highest magnetic field strength. We also obtain the distribution of mass-to-flux ratios across the clump. In the region surrounding the core, the mass-to-flux ratio is larger than 1, which indicates that the magnetic field strength is insufficient to support the region against gravitational collapse. Therefore, the change in the magnetic field orientation from clump to core scales may be the result of gravitational collapse, with the field being pulled inward along with the flow of material under gravity.}, archive = {J_ApJ}, author = {Jihye Hwang and Kate Pattle and Chang Won Lee and Janik Karoly and Kee-Tae Kim and Jongsoo Kim and Junhao Liu and Keping Qiu and A-Ran Lyo and David Eden and Patrick M. Koch and Doris Arzoumanian and Ekta Sharma and Frédérick Poidevin and Doug Johnstone and Simon Coudé and Mehrnoosh Tahani and Derek Ward-Thompson and Archana Soam and Ji-hyun Kang and Thiem Hoang and Woojin Kwon and Nguyen Bich Ngoc and Eun Jung Chung and Tyler L. Bourke and Takashi Onaka and Florian Kirchschlager and Motohide Tamura and Jungmi Kwon and Xindi Tang and Eswaraiah Chakali and Tie Liu and Pierre Bastien and Ray S. Furuya and Shih-Ping Lai and Sheng-Jun Lin and Jia-Wei Wang and David Berry}, doi = {10.3847/1538-4357/adce80}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {222}, shortjournal = {The Astrophys. J.}, title = {The JCMT BISTRO-3 survey: Variation of magnetic field orientations on parsec and subparsec scales in the massive star-forming region g28.34+0.06}, volume = {985}, year = {2025}, }
• (2025). Rising from the ashes. II. the bar-driven abundance bimodality of the milky way. ApJ, 985(2), 221. (www)

  @article{ , abstract = {The Milky Way hosts at least two modes in its present-day distribution of Fe and α -elements. The exact cause of this bimodality is disputed, but one class of explanations involves the merger between the Milky Way and a relatively massive satellite (Gaia-Sausage-Enceladus) at z ∼ 2. However, reproducing this bimodality in simulations is not straightforward, with conflicting results on the prevalence, morphology, and mechanism behind multimodality. We present a case study of a galaxy in the Illustris TNG50 simulation that undergoes sequential phases of starburst, brief quiescence, and then rejuvenation. This scenario results in a pronounced abundance bimodality after a post-processing adjustment of the [ α /Fe] of old stars designed to mimic a higher star formation efficiency in dense gas. The high- and low- α sequences are separated in time by the brief quiescent period, which is associated not with a merger but with the formation of a bar followed by active galactic nucleus (AGN) activity. This galaxy indicates a novel scenario in which the α -bimodality in the Milky Way is caused by the formation of the bar via AGN-induced quenching. In addition to a stellar age gap in the Milky Way, we predict that abundance bimodalities should be more common in barred as opposed to unbarred galaxies.}, archive = {J_ApJ}, author = {Angus Beane and James W. Johnson and Vadim A. Semenov and Lars Hernquist and Vedant Chandra and Charlie Conroy}, doi = {10.3847/1538-4357/adceab}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {221}, shortjournal = {The Astrophys. J.}, title = {Rising from the ashes. II. the bar-driven abundance bimodality of the milky way}, volume = {985}, year = {2025}, }
• (2025). Spinning spectral sirens: Robust cosmological measurement using Mass–Spin correlations in the binary black hole population. ApJ, 985(2), 220. (www)

  @article{ , abstract = {Gravitational waves from compact binary mergers provide a direct measurement of luminosity distance, which, in combination with redshift information, serves as a cosmological probe. In order to statistically infer merger redshifts, the "spectral standard siren" method relies on features, such as peaks, dips, or breaks, in the compact object mass spectrum, which get redshifted in the detector frame relative to the source frame. However, if the source-frame location of these features evolves over cosmic time, the spectral siren measurement may be biased. Some features, such as the edges of the pair-instability supernova mass gap, may be more stable than others. We point out that binary black hole (BBH) spins, which are not redshifted in the detector frame, provide a natural way to identify robust mass scales for spectral siren cosmology. For example, there is recent evidence for a mass scale in the BBH population that separates slowly spinning from more rapidly spinning BBH mergers, consistent with the lower edge of the pair-instability gap. Applying our method to data from LIGO-Virgo-KAGRA's third transient catalog, we demonstrate how to isolate this mass scale and produce a robust "spinning spectral siren" measurement of the Hubble constant {H}_{0}=8{5}_{-67}^{+99}\,{\rm{km}}\,{{\rm{s}}}^{-1}\,{{\rm{Mpc}}}^{-1} , or {H}_{0}=8{0}_{-46}^{+60}\,{\rm{km}}\,{{\rm{s}}}^{-1}\,{{\rm{Mpc}}}^{-1} when combined with other mass features, such as the ∼35 M ⊙ peak. We consider the possibility that the source-frame location of the ∼35 M ⊙ peak evolves with redshift and show that information from black hole spin can be used to mitigate the associated bias for self-calibrating spectral sirens.}, archive = {J_ApJ}, author = {Hui Tong and Maya Fishbach and Eric Thrane}, doi = {10.3847/1538-4357/adcec5}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {220}, shortjournal = {The Astrophys. J.}, title = {Spinning spectral sirens: Robust cosmological measurement using Mass–Spin correlations in the binary black hole population}, volume = {985}, year = {2025}, }
• (2025). Simulations of coronal mass ejections on a young solar-type star and their detectability through coronal spectral observations. ApJ, 985(2), 219. (www)

  @article{ , abstract = {There is a growing interest in searching for coronal mass ejections (CMEs) in other stellar systems, because they are thought to be one of the important factors shaping planetary atmospheres. We investigated the possible spectral signatures related to stellar CMEs using magnetohydrodynamic (MHD) simulations and spectral synthesis techniques. Blue-wing enhancements of the synthetic coronal line profiles caused by the line-of-sight motion of plasma were observed during the simulated CME events. We included instrumental conditions in the spectral synthesis and tested the detectability of the asymmetries under different instrumental broadening conditions. The results show that blue-wing asymmetries are visible in some extreme-ultraviolet lines with spectral resolutions higher than around 2000, and the line-of-sight velocities of CMEs obtained from asymmetry analysis techniques are comparable to the CME velocities derived from three-dimensional model outputs. However, when the spectral resolution drops below 2000, the asymmetries in the blue wings become barely visible, but blueshifts in the line centroids with velocities around −100 to −200 km s −1 are observed. We suggest a method of using MHD simulations to synthesize line profiles and analyze their asymmetries that may help to guide future instrument design, in terms of detecting stellar CMEs through Doppler shifts or the asymmetries of coronal spectral lines.}, archive = {J_ApJ}, author = {Yu Xu and Hui Tian and Julián D. Alvarado-Gómez and Jeremy J. Drake and Gustavo Guerrero}, doi = {10.3847/1538-4357/adcee7}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {219}, shortjournal = {The Astrophys. J.}, title = {Simulations of coronal mass ejections on a young solar-type star and their detectability through coronal spectral observations}, volume = {985}, year = {2025}, }
• (2025). Measuring the redshift-space distortions by cross-correlating the density fields before and after reconstruction. ApJ, 985(2), 218. (www)

  @article{ , abstract = {In this work, we develop a theoretical model for the cross-power spectrum of the matter density field before and after standard baryonic acoustic oscillation reconstruction. Using this model, we extract the redshift-space distortion parameter from the cross-power spectrum. The model is validated against a suite of high-resolution N -body simulations, demonstrating its accuracy and robustness for cosmological analyses.}, archive = {J_ApJ}, author = {Weibing Zhang and Ruiyang Zhao and Xiaoyong Mu and Kazuya Koyama and Ryuichi Takahashi and Yuting Wang and Gong-Bo Zhao}, doi = {10.3847/1538-4357/adcf21}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {218}, shortjournal = {The Astrophys. J.}, title = {Measuring the redshift-space distortions by cross-correlating the density fields before and after reconstruction}, volume = {985}, year = {2025}, }
• (2025). Magnetic accretion flow explains the hysteresis Q-diagram seen in outbursts of black hole low-mass X-ray binaries. ApJ, 985(2), 217. (www)

  @article{ , abstract = {Black hole low-mass X-ray binaries undergo quiescence-outburst cycles. During the outbursts, they typically go through a q-shaped pattern in the hardness-intensity diagram (HID), known as the hysteresis q-diagram, while the physical nature is still unknown. We argue that the hysteresis q-diagram can be well explained with a recently proposed magnetized accretion disk model. The model takes into account the saturated magnetic pressure and predicts that the standard Shakura–Sunyaev disk (SSD) has an inner truncation at relatively low accretion rates, filled with an optically thin, hot accretion flow that resembles the advection-dominated accretion flow (ADAF) inside. Given a perturbation of accretion rate, the variation of the truncation radius can be derived as a result of thermal equilibrium by comparing the heating and cooling rates. We show that the truncation radius displays a hysteresis effect in response to the variation of mass accretion rate. As a result, the spectral hardness due to competition of the soft SSD and hard ADAF components is also hysteresis along with the rise and decay of the mass accretion rate or source intensity, leading to a q-shaped diagram in the HID.}, archive = {J_ApJ}, author = {Jiahui Huang and Hua Feng and Lian Tao}, doi = {10.3847/1538-4357/add5e8}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {217}, shortjournal = {The Astrophys. J.}, title = {Magnetic accretion flow explains the hysteresis Q-diagram seen in outbursts of black hole low-mass X-ray binaries}, volume = {985}, year = {2025}, }
• (2025). Model-independent determination of the tidal deformability of a 1.4 m⊙ neutron star from gravitational-wave measurements. ApJ, 985(2), 216. (www)

  @article{ , abstract = {Tidal deformability of a 1.4 M ⊙ neutron star provides a pivotal window into the physics of dense nuclear matter, bridging gravitational-wave (GW), electromagnetic observations and nuclear physics. In this work, we present a novel, data-driven approach to constrain Λ 1.4 without invoking specific equation-of-state (EOS) models. By interpolating directly over the mass–tidal-deformability posteriors from GW170817, we obtain an EOS-independent constraint of {{\rm{\Lambda }}}_{1.4}\ =\ 222.8{9}_{-98.85}^{+420.33}. We further combine these GW-based results with the X-ray EOS-independent constraint from C. Huang, deriving a multimessenger limit of {{\rm{\Lambda }}}_{1.4}\ =\ 265.1{8}_{-104.38}^{+237.88}, which remains largely EOS agnostic. This framework demonstrates that higher-order terms neglected in linear expansion methods do not significantly affect Λ 1.4 estimates under current observational uncertainties. As GW detectors improve in sensitivity and more binary neutron-star mergers are discovered, our purely data-driven strategy can serve as a robust standard baseline for extracting neutron-star interior properties without relying on unverified EOS models.}, archive = {J_ApJ}, author = {Chun Huang}, doi = {10.3847/1538-4357/add5ef}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {216}, shortjournal = {The Astrophys. J.}, title = {Model-independent determination of the tidal deformability of a 1.4 m⊙ neutron star from gravitational-wave measurements}, volume = {985}, year = {2025}, }
• (2025). CHILES. VIII. probing the evolution of average h i content in star-forming galaxies over the past 5 gyr. ApJ, 985(2), 215. (www)

  @article{ , abstract = {Utilizing the COSMOS H I Large Extragalactic Survey (CHILES) data set, we investigate the evolution of the average atomic neutral hydrogen (H I ) properties of galaxies over the continuous redshift range 0.09 < z < 0.47. First, we introduce a simple multistep, multiscale imaging and continuum subtraction process that we apply to each observing session. These sessions are then averaged onto a common uv -grid and run through a Fourier filtering artifact mitigation technique. We then demonstrate how this process results in science quality data products by comparing to the expected noise and image-cube kurtosis. This work offers the first-look description and scientific analysis after the processing of the entire CHILES database. These data are used to measure the average H I mass in four redshift bins, out to a redshift 0.47, by separately stacking blue cloud (near-UV, NUV- r = −1 to 3) and red sequence (NUV- r = 3–6) galaxies. We find little-to-no change in gas fraction for the total ensemble of blue galaxies and make no detection for red galaxies. Additionally, we split up our sample of blue galaxies into an intermediate stellar mass bin ( M * = 10 9−10 M ⊙ ) and a high stellar mass bin ( M * = 10 10−12.5 M ⊙ ). We find that in the high-mass bin galaxies are becoming increasingly H I poor with decreasing redshift, while the intermediate-mass galaxies maintain a constant H I gas mass. We place these results in the context of the star-forming main sequence of galaxies and hypothesize about the different mechanisms responsible for their different evolutionary tracks.}, archive = {J_ApJ}, author = {Nicholas Luber and D. J. Pisano and J. H. van Gorkom and Julia Blue Bird and Richard Dodson and Hansung B. Gim and Kelley M. Hess and Lucas R. Hunt and Danielle Lucero and Martin Meyer and Emmanuel Momjian and Min S. Yun}, doi = {10.3847/1538-4357/adc715}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {215}, shortjournal = {The Astrophys. J.}, title = {CHILES. VIII. probing the evolution of average h i content in star-forming galaxies over the past 5 gyr}, volume = {985}, year = {2025}, }
• (2025). CHILES. IX. observational and simulated h i content and star formation of blue galaxies in different cosmic web environments. ApJ, 985(2), 214. (www)

  @article{ , abstract = {We examine the redshift evolution of the relationship between the neutral atomic hydrogen (H i ) content and star formation properties of blue galaxies, along with their location in the cosmic web. Using the COSMOS H i Large Extragalactic Survey (CHILES) and the IllustrisTNG (TNG100) cosmological simulation, and the DisPerSE algorithm, we identify the filamentary structure in both observations and simulations, measure the distance of galaxies to the nearest filament spine D fil , and calculate the mean H i gas fraction and the relative specific star formation rate (sSFR) of blue galaxies in three different cosmic web environments—0 < D fil /Mpc < 2 (filament cores), 2 < D fil /Mpc < 4 (filament outskirts), and 4 < D fil /Mpc < 20 (voids). We find that, although there are some similarities between CHILES and TNG, there exist significant discrepancies in the dependence of H i and star formation on the cosmic web and on redshift. TNG overpredicts the observed H i fraction and relative sSFR at z = 0–0.5, with the tension being strongest in the voids. CHILES observes a decline in the H i fraction from filament cores to voids, exactly the opposite of the trend predicted by TNG. CHILES observes an increase in H i fraction at z = 0.5 → 0 in the voids, while TNG predicts an increase in this time in all environments. Further dividing the sample into stellar mass bins, we find that the H i in \mathrm{log}({M}_{* }/{M}_{\odot })\gt 10 galaxies is better reproduced by TNG than H i in \mathrm{log}({M}_{* }/{M}_{\odot })=9-10 galaxies.}, archive = {J_ApJ}, author = {Nicholas M. Luber and Farhanul Hasan and J. H. van Gorkom and D. J. Pisano and Joseph N. Burchett and Julia Blue Bird and Hansung B. Gim and Kelley M. Hess and Lucas R. Hunt and David C. Koo and Sushma Kurapati and Danielle Lucero and Nir Mandelker and Martin Meyer and Emmanuel Momjian and Daisuke Nagai and Joel R. Primack and Min S. Yun}, doi = {10.3847/1538-4357/adc448}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {214}, shortjournal = {The Astrophys. J.}, title = {CHILES. IX. observational and simulated h i content and star formation of blue galaxies in different cosmic web environments}, volume = {985}, year = {2025}, }
• (2025). The discovery of two quadruple star systems with the second and third shortest outer periods. ApJ, 985(2), 213. (www)

  @article{ , abstract = {We present the discovery of two quadruple star systems—TIC 285853156 and TIC 392229331—each consisting of two bound eclipsing binary stars. Among the most compact quadruples known, TIC 392229331 and TIC 285853156 have the second and third shortest outer orbital periods (145 days and 152 days, respectively) after BU Canis Minoris (122 days). We demonstrate that both systems are long-term dynamically stable despite substantial outer orbital eccentricities (0.33 for TIC 285853156 and 0.56 for TIC 392229331). We previously reported these systems in V. B. Kostov et al. and V. B Kostov et al. as 2 + 2 hierarchical quadruple candidates producing two sets of primary and secondary eclipses in TESS data, as well as prominent eclipse timing variations on both binary components. We combine all available TESS data and new spectroscopic observations into a comprehensive photodynamical model, proving that the component binary stars are gravitationally bound in both systems and finding accurate stellar and orbital parameters for both systems, including very precise determinations of the outer periods. TIC 285853156 and TIC 392229331 represent the latest addition to the small population of well-characterized proven quadruple systems dynamically interacting on detectable timescales.}, archive = {J_ApJ}, author = {Brian P. Powell and Guillermo Torres and Veselin B. Kostov and Tamás Borkovits and Saul A. Rappaport and Maxwell Moe and David W. Latham and Thomas L. Jacobs and Robert Gagliano and Martti H. K. Kristiansen and Mark Omohundro and Hans M. Schwengeler and Daryll M. LaCourse and Ivan A. Terentev and Allan R. Schmitt}, doi = {10.3847/1538-4357/adcece}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {213}, shortjournal = {The Astrophys. J.}, title = {The discovery of two quadruple star systems with the second and third shortest outer periods}, volume = {985}, year = {2025}, }
• (2025). A multiwavelength technique for estimating galaxy cluster mass accretion rates. ApJ, 985(2), 212. (www)

  @article{ , abstract = {The mass accretion rate of galaxy clusters is a key factor in determining their structure, but a reliable observational tracer has yet to be established. We present a state-of-the-art machine learning model for constraining the mass accretion rate of galaxy clusters from only X-ray and thermal Sunyaev–Zeldovich observations. Using idealized mock observations of galaxy clusters from the MillenniumTNG simulation, we train a machine learning model to estimate the mass accretion rate. The model constrains 68% of the mass accretion rates of the clusters in our data set to within 33% of the true value without significant bias, a ∼58% reduction in the scatter over existing constraints. We demonstrate that the model uses information from both radial surface brightness density profiles and asymmetries.}, archive = {J_ApJ}, author = {John Soltis and Michelle Ntampaka and Benedikt Diemer and John ZuHone and Sownak Bose and Ana Maria Delgado and Boryana Hadzhiyska and César Hernández-Aguayo and Daisuke Nagai and Hy Trac}, doi = {10.3847/1538-4357/adcfa4}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {212}, shortjournal = {The Astrophys. J.}, title = {A multiwavelength technique for estimating galaxy cluster mass accretion rates}, volume = {985}, year = {2025}, }
• (2025). Discovery of evolution of the temporal features of X-ray bursts from SGR j1935+2154. ApJ, 985(2), 211. (www)

  @article{ , abstract = {SGR J1935+2154 has undergone eight active episodes since its discovery in 2014. In this study, our focus is on the evolution of the temporal characteristics including burst duration, minimum variation timescale (MVT), and waiting time across these active episodes observed by Fermi/Gamma-ray Burst Monitor (GBM). We find a linear increase in the logarithmic mean of burst duration over time, with a deviation during the fourth and eighth active episodes containing X-ray burst (XRB)−Fast Radio Burst (FRB) 200428 and XRB−radio burst 221021 association events. We also find a possible increasing burst frequency, with the fourth active episode exhibiting an exceptionally high burst rate. Therefore, XRB−FRB 200428 is potentially triggered by energetic events such as a large crust, magnetic reconnection, or glitches. The MVT analysis reveals deviations in the sixth and seventh active episodes with ∼3 σ . These results may suggest evolving magnetospheric field geometry, neutron star crust, and energy release mechanisms of SGR J1935+2154. Finally, our findings predict that longer XRB durations indicate the highly likely occurrence of XRB and radio burst association events, warranting focused multiwavelength observations during such episodes, which will also be further confirmed or disproved by future observations.}, archive = {J_ApJ}, author = {Shuo Xiao and Jiao-Jiao Yang and Lin- Lin and Shu-Xu Yi and Shao-Lin Xiong and Tong-Lei Liao and Zheng-Huo Jiang and Zhen Zhang and Ming-Yu Ge and Shuang-Nan Zhang}, doi = {10.3847/1538-4357/add401}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {211}, shortjournal = {The Astrophys. J.}, title = {Discovery of evolution of the temporal features of X-ray bursts from SGR j1935+2154}, volume = {985}, year = {2025}, }
• (2025). Low-acceleration gravitational anomaly from bayesian 3D modeling of wide binary orbits: Methodology and results with gaia data release 3. ApJ, 985(2), 210. (www)

  @article{ , abstract = {Isolated wide binary stars provide natural laboratories to directly probe gravity for Newtonian acceleration of g N ≲ 10 −9 m s −2 . Recent statistical analyses of wide binaries have been performed only with sky-projected relative velocities v p in the pairs. A new method of Bayesian orbit modeling exploiting three relative velocity components including the radial (line-of-sight) component v r is developed to measure the gravitational anomaly parameter {\rm{\Gamma }}\equiv {\mathrm{log}}_{10}\sqrt{{\gamma }_{g}}\equiv {\mathrm{log}}_{10}\sqrt{{G}_{{\rm{eff}}}/{G}_{{\rm{N}}}} where G eff is the effective gravitational constant for pseudo-Newtonian elliptical orbits, while G N is Newton's constant. The method infers individual probability distributions of Γ and then combines the independent distributions to obtain a consolidated distribution in a specific range of g N . Here the method is described and applied to a sample of 312 wide binaries in a broad dynamic range of 10 −11.0 ≲ g N ≲ 10 −6.7 m s −2 with v r uncertainties in the range 168\lt {\sigma }_{{v}_{r}}\lt 380 m s −1 selected from the Gaia Data Release 3 database. The following results are obtained: Γ = 0.000 ± 0.011 or γ g = 1.00 ± 0.05 ( N binary = 125) for the high-acceleration regime (10 −7.9 ≲ g N ≲ 10 −6.7 m s −2 ) agreeing well with Newton, but Γ = 0.085 ± 0.040 or {\gamma }_{g}=1.4{8}_{-0.23}^{+0.33} (35) for the modified Newtonian dynamics (MOND) regime (10 −11.0 ≲ g N ≲ 10 −9.5 m s −2 ) and Γ = 0.063 ± 0.015 or {\gamma }_{g}=1.3{4}_{-0.08}^{+0.10} (111) for the MOND + transition regime (10 −11.0 ≲ g N ≲ 10 −8.5 m s −2 ). These results show that a gravitational anomaly is evident for g N ≲ 10 −9 m s −2 and Γ in the MOND regime (≲10 −9.5 m s −2 ) agrees with the first-tier prediction (Γ ≈ 0.07 or γ g ≈ 1.4) of MOND gravity theories.}, archive = {J_ApJ}, author = {Kyu-Hyun Chae}, doi = {10.3847/1538-4357/adce09}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {210}, shortjournal = {The Astrophys. J.}, title = {Low-acceleration gravitational anomaly from bayesian 3D modeling of wide binary orbits: Methodology and results with gaia data release 3}, volume = {985}, year = {2025}, }
• (2025). Effects of planetary parameters on disequilibrium chemistry in irradiated planetary atmospheres: From gas giants to sub-neptunes. ApJ, 985(2), 209. (www)

  @article{ , abstract = {A primary goal of characterizing exoplanet atmospheres is to constrain planetary bulk properties, such as their metallicity, C/O ratio, and intrinsic heat. However, there are significant uncertainties in many aspects of atmospheric physics, such as the strength of vertical mixing. Here, we use PICASO and the photochem model to explore how atmospheric chemistry is influenced by planetary properties such as metallicity, C/O ratio, T int , T eq , and K zz in hydrogen-dominated atmospheres. We vary the T eq of the planets between 400 and 1600 K, across "cold," "warm," and "hot" objects. We also explore an extensive range of T int values between 30 and 500 K, representing sub-Neptunes to massive gas giants. We find that gases such as CO and CO 2 show a drastically different dependence on K zz and C/O for planets with cold interiors (e.g., sub-Neptunes) compared to planets with hotter interiors (e.g., Jupiter mass planets) for the same T eq . We also find that gases such as CS and CS 2 can carry a significant portion of the S-inventory in the upper atmosphere near T eq ≤ 600 K, below which SO 2 ceases to be abundant. For solar C/O, we show that the CO/CH 4 ratio in the upper atmospheres of planets can become ≤1 for planets with low T eq , but only if their interiors are cold ( T int ≤ 100 K). We find that photochemical haze precursor molecules in the upper atmosphere show very complex dependence on C/O, K zz , T eq , and T int for planets with cold interiors (e.g., sub-Neptunes). We also briefly explore fully coupling PICASO and photochem to generate self-consistent radiative–convective–photochemical-equilibrium models.}, archive = {J_ApJ}, author = {Sagnick Mukherjee and Jonathan J. Fortney and Nicholas F. Wogan and David K. Sing and Kazumasa Ohno}, doi = {10.3847/1538-4357/adc7b3}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {209}, shortjournal = {The Astrophys. J.}, title = {Effects of planetary parameters on disequilibrium chemistry in irradiated planetary atmospheres: From gas giants to sub-neptunes}, volume = {985}, year = {2025}, }
• (2025). Exploring the anisotropic gravitational wave background from all-sky mock gravitational wave event catalogs. ApJ, 985(2), 208. (www)

  @article{ , abstract = {Anisotropic stochastic gravitational wave background (SGWB) serves as a potential probe of the large-scale structure (LSS) of the universe. In this work, we explore the anisotropic SGWB from local ( z < ∼ 0.085) merging stellar mass compact binaries, specifically focusing on merging stellar binary black holes, merging neutron star–black hole binaries, and merging binary neutron stars. The analysis employs seven all-sky mock lightcone gravitational wave event catalogs, which are derived from the Millennium simulation combined with a semianalytic model of galaxy formation and a binary population synthesis model. We calculate the angular power spectra C ℓ at multipole moments ℓ , expressed as log 10 [ ℓ ( ℓ + 1)C ℓ /(2 π )], based on the skymaps of the overdensity δ GW in the anisotropic SGWB. The spectra for all three source types exhibit an approximately linear increase with log 10 ℓ at higher ℓ (e.g., ℓ > ∼ 30–300) in seven catalogs, with a characteristic slope of ∼2. The spectra of seven catalogs exhibit considerable variations, arising from fluctuations in spatial distribution, primarily in the radial distribution, of nearby sources (e.g., <50 Mpc h −1 ). After subtracting these nearby sources, the variations become much smaller and the spectra for the three source types become closely aligned (within discrepancies of a factor of ∼2 across ℓ = 1–1000 for all catalogs). We also find that including farther sources results in a rapid decrease in the anisotropy.}, archive = {J_ApJ}, author = {Zhencheng Li and Zhen Jiang and Yun Liu and Xi-Long Fan and Liang Gao and Yun Chen and Tengpeng Xu}, doi = {10.3847/1538-4357/adca36}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {208}, shortjournal = {The Astrophys. J.}, title = {Exploring the anisotropic gravitational wave background from all-sky mock gravitational wave event catalogs}, volume = {985}, year = {2025}, }
• (2025). Exploring the spectral energy distributions of luminous broad absorption line quasars at high redshift. ApJ, 985(2), 207. (www)

  @article{ , abstract = {We present the multiwavelength spectral energy distributions (SEDs) for 65 luminous broad absorption line (BAL) quasars with redshifts 1.55 ≲ z ≲ 3.50 from the Gemini Near Infrared Spectrograph–Distant Quasar Survey (GNIRS-DQS). We integrate data from a variety of ground- and space-based observatories to construct a comprehensive spectral profile of these objects from radio through X-rays. In addition, we present a mid-infrared to X-ray composite SED of these sources. Our data set represents the most uniform sample of BAL quasars, providing a statistically robust set of SEDs. Our findings indicate that the BAL quasars in the GNIRS-DQS sample exhibit significant reddening in the ultraviolet-optical continuum relative to their non-BAL counterparts, consistent with previous studies. Notably, our analysis reveals no significant differences in the mid- or near-infrared spectral regime between BAL and non-BAL quasars. In line with previous work, we find no strong evidence that BAL and non-BAL quasars possess fundamentally different SEDs, also consistent with recent findings that both groups display similar rest-frame optical emission-line properties.}, archive = {J_ApJ}, author = {Harum Ahmed and Sarah C. Gallagher and Ohad Shemmer and Michael S. Brotherton and Cooper Dix and Leigh Parrott and Gordon T. Richards}, doi = {10.3847/1538-4357/adca38}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {207}, shortjournal = {The Astrophys. J.}, title = {Exploring the spectral energy distributions of luminous broad absorption line quasars at high redshift}, volume = {985}, year = {2025}, }
• (2025). The link between galaxy structure properties and star formation in local galaxies. ApJ, 985(2), 206. (www)

  @article{ , abstract = {To investigate the role of morphology in galaxy evolution, we analyze the relationships between galaxy structure, star formation, and H i gas content. Using multiband images from the DESI Legacy Imaging Surveys, we perform detailed structural decompositions on a representative local galaxy sample from xGASS. Structural components and color properties are examined as functions of deviations from the star formation main sequence (ΔSFR MS ) and H i gas deficiency (Δ f H I ). We find that bulge fractions decrease with higher ΔSFR MS and lower stellar mass, indicating that star-forming galaxies are predominantly disk dominated while quiescent galaxies are bulge dominated. The slope of the color ( g − r ) versus ΔSFR MS relationship decreases from low to high stellar masses and from outer to inner regions, with greater color variation in massive galaxies. Color gradients are predominantly negative, becoming shallower in lower-mass galaxies and in the outer disk regions. We also identify inflection points in the color gradient and bulge fraction relations with ΔSFR MS , with main-sequence galaxies having the lowest bulge fractions and steepest color gradients. At fixed stellar mass, we observe only a slight correlation between bulge fraction and H i deficiency. However, outer disk colors show a stronger dependence on H i content than inner regions, and color gradients flatten as Δ f H I increases. These results suggest that H i gas is more closely linked to star-forming, disk-dominated systems, supporting the idea that gas accretion fuels star formation primarily in galaxy disks.}, archive = {J_ApJ}, author = {Zhimin Zhou and Wenwen Wang}, doi = {10.3847/1538-4357/adceed}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {206}, shortjournal = {The Astrophys. J.}, title = {The link between galaxy structure properties and star formation in local galaxies}, volume = {985}, year = {2025}, }
• (2025). Spin-polarized electrons from magnetically aligned grains and chiral symmetry breaking: Effects of cosmic rays in protostellar environments. ApJ, 985(2), 205. (www)

  @article{ , abstract = {Low-energy spin-polarized electrons (SPEs) are thought to cause symmetry breaking and could explain the origin of homochirality of prebiotic molecules such as amino acids and sugars. Here we study the effect of cosmic rays (CRs) on the emission of SPEs from aligned grains in dense protostellar environments and explore their effects on chiral asymmetry of prebiotic molecules. We first show that icy grains in protostellar environments can align with magnetic fields due to magnetically enhanced radiative torque mechanism. We then study the production of thermal electrons by CR ionization of H 2 and the CR-induced UV radiation using the attenuated CR spectra in dense cores obtained from a continuous slowing down model. Next, we show that thermal electrons with initial random spins captured by aligned grains will become spin-polarized due to the Barnett effect, converting unpolarized electrons into SPEs. We calculate the rate of photoemission of such SPEs by CRs-induced UV radiation and secondary electron emission from aligned grains and find that the photoemission by CRs-induced UV radiation is dominant. Finally, we calculate the total production rate of SPEs inside aligned dust grains by CRs. We estimate the alignment degree of SPEs from superparmagnetic (SPM) grains and find that it is only significant for SPM grains having large iron clusters and fast rotation. We suggest that low-energy secondary SPEs from aligned superparamagnetic grains with large iron inclusions induced by CRs might cause the chiral asymmetry of chiral prebiotic molecules formed in the ice mantle of aligned grains (analogously to UV circularly polarized light). We propose that amino acids and sugars of chiral asymmetry detected in meteorite/asteroids/comets might be formed in icy grain mantles with superparamagnetic inclusions under the irradiation of SPEs released from aligned grains by CRs in protostellar environments.}, archive = {J_ApJ}, author = {Thiem Hoang}, doi = {10.3847/1538-4357/adcef1}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {205}, shortjournal = {The Astrophys. J.}, title = {Spin-polarized electrons from magnetically aligned grains and chiral symmetry breaking: Effects of cosmic rays in protostellar environments}, volume = {985}, year = {2025}, }
• (2025). Merger-driven turbulence and coherent transport in the intracluster medium. ApJ, 985(2), 204. (www)

  @article{ , abstract = {The distribution of metals and temperature in the intracluster medium (ICM) provides key insights into galaxy cluster evolution, revealing information about chemical enrichment and heating and cooling processes, respectively. To access this information, it is crucial to understand the transport processes in the ICM. Here, we systematically study the transport mechanisms in the ICM with tracer particle resimulations of the Omega500 cosmological hydrosimulation, using a sample of four galaxy clusters of comparable masses but different mass assembly histories. Through the analysis of particle pair dispersion statistics, we find a time-dependent scaling index linked to the cluster's dynamical state. It reaches or exceeds Richardson scaling briefly during major mergers but remains much lower in relaxed clusters. We identify a coherent transport mode during major mergers that causes directional flow in the ICM. Although coherent transport can move particles to outer regions, the particles transported to the cluster outskirts compose only a small fraction of the density there; thus, the anisotropy it creates in the overall density distribution is limited. Moreover, strong turbulence generated by mergers quickly disperses these particles, further limiting this effect. We also provide useful statistics on the radial evolution of the ICM and the fraction of particles that ever reached the inner regions as a function of radius. Our results show that major mergers primarily drive particle transport, linking ICM transport to merger-driven dynamics, and highlighting the interplay between coherent and turbulent transport.}, archive = {J_ApJ}, author = {Yiwei Zhang and Xun Shi and Daisuke Nagai}, doi = {10.3847/1538-4357/add1b4}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {204}, shortjournal = {The Astrophys. J.}, title = {Merger-driven turbulence and coherent transport in the intracluster medium}, volume = {985}, year = {2025}, }
• (2025). Status report on the chicago-carnegie hubble program (CCHP): Measurement of the hubble constant using the hubble and james webb space telescopes. ApJ, 985(2), 203. (www)

  @article{ , abstract = {We present the latest results from the Chicago-Carnegie Hubble Program to measure the Hubble constant, using data from the James Webb Space Telescope (JWST). The overall program aims to calibrate three independent methods: (1) tip of the red giant branch (TRGB) stars, (2) J -region asymptotic giant branch (JAGB) stars, and (3) Cepheids. To date, our program includes 10 nearby galaxies, hosting 11 Type Ia supernovae (SNe Ia) suitable for measuring the Hubble constant ( H 0 ). It also includes the galaxy NGC 4258, whose geometric distance provides the zero-point calibration. In this paper, we discuss our results from the TRGB and JAGB methods. Our current best (highest-precision) estimate is H 0 = 70.39 ± 1.22 (stat) ± 1.33 (sys) ± 0.70 ( σ SN ), based on the TRGB method alone, with a total of 24 SN Ia calibrators from both Hubble Space Telescope and JWST data. Based on our new JWST data only, and tying into SNe Ia, we find values of H 0 = 68.81 ± 1.79 (stat) ± 1.32 (sys) for the TRGB, and H 0 = 67.80 ± 2.17 (stat) ± 1.64 (sys) km s −1 Mpc −1 for the JAGB method. The distances measured using the TRGB and the JAGB methods agree, on average, at a level better than 1%, and with the SHoES Cepheid distances at just over the 1% level. Our results are consistent with the current standard Lambda cold dark matter (ΛCDM) model, without the need for the inclusion of additional new physics. Future JWST data will be required to increase the precision and accuracy of the local distance scale.}, archive = {J_ApJ}, author = {Wendy L. Freedman and Barry F. Madore and Taylor J. Hoyt and In Sung Jang and Abigail J. Lee and Kayla A. Owens}, doi = {10.3847/1538-4357/adce78}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {203}, shortjournal = {The Astrophys. J.}, title = {Status report on the chicago-carnegie hubble program (CCHP): Measurement of the hubble constant using the hubble and james webb space telescopes}, volume = {985}, year = {2025}, }
• (2025). Hunting for high-mass X-ray binaries in the galactic center with NuSTAR. ApJ, 985(2), 202. (www)

  @article{ , abstract = {The central 2 × 0.8 deg 2 region of our Galaxy contains ∼10,000 X-ray point sources that were detected by a series of Chandra observations over the last two decades. However, the limited bandpass of Chandra below 8 keV hampered their spectroscopic classification. In 2016, the initial NuSTAR Galactic center (GC) survey detected 77 X-ray sources above 10 keV. The hard X-ray detections indicate magnetic cataclysmic variables, low-mass X-ray binaries, high-mass X-ray binaries (HMXBs), or even pulsars. The possibility of HMXB detections is particularly interesting given the dearth of identified HMXBs in the GC. We conducted a search for bright ( K s ≲ 16 mag) near-infrared (NIR) counterparts to the hard X-ray sources—utilizing their Chandra positions—in order to identify HMXB candidates. We identified seven NuSTAR sources with NIR counterpart candidates whose magnitudes are consistent with HMXBs at the GC. We assessed the likelihood of random association for these seven sources, and determined that two have a nonrandom association with a probability exceeding 99.98%, making them strong HMXB candidates. We analyzed broadband NuSTAR, Chandra, and XMM-Newton spectral data for these two candidates, one of which was previously identified as a red supergiant. We find that the X-ray spectra are consistent with HMXBs. If confirmed through follow-up NIR spectroscopic studies, our findings will open a new window into our understanding of the intrinsic luminosity distribution of HMXBs in our Galaxy in general and the GC HMXB population in particular.}, archive = {J_ApJ}, author = {Shifra Mandel and Julian Gerber and Kaya Mori and Ceaser Stringfield and Mabel Peñaherrera and Charles J. Hailey and Alan Du and Jonathan Grindlay and JaeSub Hong and Gabriele Ponti and John A. Tomsick and Maureen van den Berg}, doi = {10.3847/1538-4357/adc07e}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {202}, shortjournal = {The Astrophys. J.}, title = {Hunting for high-mass X-ray binaries in the galactic center with NuSTAR}, volume = {985}, year = {2025}, }
• (2025). Halfway to the peak: Ice absorption bands at z ≈ 0.5 with JWST MIRI/MRS. ApJ, 985(2), 201. (www)

  @article{ , abstract = {This paper presents the first combined detections of CO 2 , CO, XCN, and water ices beyond the local Universe. We find gas-phase CO in addition to the solid phase CO. Our source, SSTXFLS J172458.3+591545, is a z = 0.494 star-forming galaxy that also hosts a deeply obscured AGN. The profiles of its ice features are consistent with those of other Galactic and local galaxy sources, and the implied ice mantle composition is similar to that of even more obscured sources. The ice features indicate the presence of a compact nucleus in our Galaxy and allow us to place constraints on its density and temperature ( n > 10 5 cm −3 and T = 20–90 K). We infer the visual extinction towards this nucleus to be A V ≈ 6–7. An observed plot of τ Si versus τ CO2 / τ Si can be viewed as a probe for both the total dustiness of a system as well as the clumpiness of the dust along the line of sight. This paper highlights the potential of using JWST MIRI spectra to study the dust composition and geometric distribution of sources beyond the local Universe.}, archive = {J_ApJ}, author = {Anna Sajina and Alexandra Pope and Henrik Spoon and Lee Armus and Miriam Eleazer and Duncan Farrah and Mark Lacy and Thomas Lai and Jed McKinney and Sylvain Veilleux and Lin Yan and Jason Young}, doi = {10.3847/1538-4357/adc44a}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {201}, shortjournal = {The Astrophys. J.}, title = {Halfway to the peak: Ice absorption bands at z ≈ 0.5 with JWST MIRI/MRS}, volume = {985}, year = {2025}, }
• (2025). Learning to see: Applying inverse recurrent inference machines to see through refractive scattering. ApJ, 985(2), 200. (www)

  @article{ , abstract = {The Event Horizon Telescope (EHT) has produced horizon-resolving images of Sagittarius A* (Sgr A*). Scattering in the turbulent plasma of the interstellar medium distorts the appearance of Sgr A* on scales only marginally smaller than the fiducial resolution of EHT. The scattering process both diffractively blurs and adds stochastic refractive substructures that limits the practical angular resolution of EHT images of Sgr A*. We explore the ability of a novel recurrent neural network machine learning framework to mitigate these scattering effects, after training on sample data that are agnostic to general relativistic magnetohydrodynamics (GRMHD). We demonstrate that if instrumental limitations are negligible, it is possible to nearly completely mitigate interstellar scattering at a wavelength of 1.3 mm. We validate and quantify the fidelity of this scattering mitigation scheme with physically relevant GRMHD simulations. We find that we can accurately reconstruct resolved structures at the scale of 3 μ as, well below the nominal instrumental resolution of EHT, 24 μ as.}, archive = {J_ApJ}, author = {Arvin Kouroshnia and Kenny Nguyen and Chunchong Ni and Ali SaraerToosi and Avery E. Broderick}, doi = {10.3847/1538-4357/adcabf}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {200}, shortjournal = {The Astrophys. J.}, title = {Learning to see: Applying inverse recurrent inference machines to see through refractive scattering}, volume = {985}, year = {2025}, }
• (2025). Search for kink events in variable fermi-LAT blazars. ApJ, 985(2), 199. (www)

  @article{ , abstract = {This study explores the detection of quasiperiodic oscillations (QPOs) in blazars as a method to identify kink events within their jets, utilizing both γ -ray and polarized light observations. Focusing on a sample of nine blazars, we analyze γ -ray light curves to identify significant QPOs. In addition to γ -ray data, we incorporated polarized light data corresponding to the same temporal segments to cross-validate the presence of QPOs. However, the limited availability of comprehensive polarized data restricted our ability to perform a thorough analysis across all data sets. Despite these limitations, our analysis reveals a segment where QPOs in polarized light coincided with those observed in γ -rays, providing preliminary evidence supporting the kink origin of these oscillations.}, archive = {J_ApJ}, author = {P. Peñil and H. Zhang and J. Otero-Santos and M. Ajello and S. Buson and S. Adhikari and A. Rico and J. Escudero Pedrosa and I. Agudo and D. Morcuende and A. Sota and V. Casanova and F. J. Aceituno}, doi = {10.3847/1538-4357/adcbab}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {199}, shortjournal = {The Astrophys. J.}, title = {Search for kink events in variable fermi-LAT blazars}, volume = {985}, year = {2025}, }
• (2025). Large cold dust reservoir revealed in transitional SN ib 2014C by james webb space telescope mid-infrared spectroscopy. ApJ, 985(2), 198. (www)

  @article{ , abstract = {Supernova (SN) 2014C is a rare transitional event that exploded as a hydrogen-poor, helium-rich Type Ib SN and subsequently interacted with a hydrogen-rich circumstellar medium (CSM) a few months postexplosion. This unique interacting object provides an opportunity to probe the mass-loss history of a stripped-envelope SN progenitor. Using the James Webb Space Telescope (JWST), we observed SN 2014C with the Mid-Infrared Instrument Medium Resolution Spectrometer at 3477 days postexplosion (rest frame), and the Near-Infrared Spectrograph Integral Field Unit at 3568 days postexplosion, covering 1.7–25 μ m. The bolometric luminosity indicates that the SN is still interacting with the same CSM that was observed with the Spitzer Space Telescope 40–1920 days postexplosion. JWST spectra and near-contemporaneous optical and near-infrared spectra show strong [Ne ii ] 12.831 μ m, He 1.083 μ m, H α , and forbidden oxygen ([O i ] λλ 6300, 6364, [O ii ] λλ 7319, 7330, and [O iii ] λλ 4959, 5007) emission lines with asymmetric profiles, suggesting a highly asymmetric CSM. The mid-IR continuum can be explained by ∼0.036 M ⊙ of carbonaceous dust at ∼300 K and ∼0.043 M ⊙ of silicate dust at ∼200 K. The observed dust mass has increased tenfold since the last Spitzer observation 4 yr ago, with evidence suggesting that new grains have condensed in the cold dense shell between the forward and reverse shocks. This dust mass places SN 2014C among the dustiest SNe in the mid-IR and supports the emerging observational trend that SN explosions produce enough dust to explain the observed dust mass at high redshifts.}, archive = {J_ApJ}, author = {Samaporn Tinyanont and Ori D. Fox and Melissa Shahbandeh and Tea Temim and Robert Williams and Kittipong Wangnok and Armin Rest and Ryan M. Lau and Keiichi Maeda and Jacob E. Jencson and Katie Auchettl and Alexei V. Filippenko and Conor Larison and Chris Ashall and Thomas G. Brink and Kyle W. Davis and Luc Dessart and Ryan J. Foley and Lluís Galbany and Matthew Grayling and Joel Johansson and Mansi M. Kasliwal and Zachary G. Lane and Natalie LeBaron and Dan Milisavljevic and Jeonghee Rho and Itsuki Sakon and Arkaprabha Sarangi and Tamás Szalai and Kirsty Taggart and Schuyler D. Van Dyk and Qinan Wang and Yi Yang and WeiKang Zheng and Szanna Zsíros}, doi = {10.3847/1538-4357/adccc0}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {198}, shortjournal = {The Astrophys. J.}, title = {Large cold dust reservoir revealed in transitional SN ib 2014C by james webb space telescope mid-infrared spectroscopy}, volume = {985}, year = {2025}, }
• (2025). Detecting intermediate-mass black holes using quasar microlensing. ApJ, 985(2), 197. (www)

  @article{ , abstract = {Recent studies suggest that numerous intermediate-mass black holes (IMBHs) may wander undetected across the Universe, emitting little radiation. These IMBHs largely preserve their birth masses, offering critical insights into the formation of heavy black hole seeds and the dynamical processes driving their evolution. We propose that such IMBHs could produce detectable microlensing effects on quasars. Their Einstein radii, comparable to the scale of quasar broad-line regions, magnify radiation from the accretion disk and broad emission lines, making these quasars outliers in flux scaling relations. Meanwhile, the microlensing causes long-term, quasi-linear variability that is distinguishable from the stochastic variability of quasars through its coherent multiwavelength behavior. We develop a matched-filtering technique that effectively separates the long-term lensing signal from the intrinsic quasar variability, with sensitivity tripling each time the observational time span doubles. Moreover, as IMBHs are often surrounded by dense star clusters, their combined gravitational field produces substantial extended, concentric caustics. These caustics induce significant variability in optical, ultraviolet, and X-ray bands over decade timescales, alongside hour-to-day-scale flux fluctuations in broad emission lines. We predict a substantial number of detectable events in the upcoming surveys by the Vera C. Rubin Observatory, considering recent IMBH mass density estimates. Even in the absence of positive detections, searches for these microlensing signals will place meaningful constraints on the cosmological mass density of IMBHs, advancing our understanding of their role in cosmic evolution.}, archive = {J_ApJ}, author = {Zihao Wu and Luis C. Ho}, doi = {10.3847/1538-4357/adcec3}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {197}, shortjournal = {The Astrophys. J.}, title = {Detecting intermediate-mass black holes using quasar microlensing}, volume = {985}, year = {2025}, }
• (2025). New insights into lava tube formation: An asymmetrical and deep case observed by yutu-2 radar at lunar farside. ApJ, 985(2), 196. (www)

  @article{ , abstract = {This article reports a potential lava tube observed at ∼130 m depth of the lunar farside by Lunar Penetrating Radar data. However, a possible scenario with a kind of dry and low-density materials connected with a basaltic boulder or lava flow cannot be excluded. If the lava tube is valid, it is at the edge of a huge paleo-depression with a maximum width of ∼26 m and a height of ∼16 m. It presents bright and phase-reversed reflections, a depressed roof, and asymmetrical reflected power on the radargram. Estimation results of the loss tangent provide evidence for it and simultaneously reveal the residual basalt material in the western region of the tube. The ancient lava flow is thought to postdate the adjacent ejecta and has high FeO+TiO 2 content. Comprehensive analyses demonstrate that the lava flow inflation, the looseness of the adjacent ejecta, and the depressed paleo-terrain may cause horizontal erosion, subsequent deceleration, and final residue of the lava. Subsequent differential compaction of overlying strata resulted in its deformation and the accumulation of pyroclastic materials in it. The results may provide unprecedented knowledge about the formation mechanisms and interior structures of lava tubes on the Moon.}, archive = {J_ApJ}, author = {Haoqiu Zhou and Xuan Feng and Zejun Dong and Chunyu Ding and Ling Zhang and Cai Liu and Wenjing Liang}, doi = {10.3847/1538-4357/adcf18}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {196}, shortjournal = {The Astrophys. J.}, title = {New insights into lava tube formation: An asymmetrical and deep case observed by yutu-2 radar at lunar farside}, volume = {985}, year = {2025}, }
• (2025). Variabilities of gamma-ray bursts from the dynamics of fallback material after tidal disruption. ApJ, 985(2), 195. (www)

  @article{ , abstract = {The gamma-ray bursts GRB 211211A and GRB 060614, believed to originate from the merger of compact objects, exhibit similarities to the jetted tidal disruption event (TDE) Sw J1644+57, by showing violent variabilities in the light curve during the decay phase. Previous studies suggest that such fluctuations in TDE may arise from the fallback of tidal disrupted debris. In this paper, we introduce the fluctuations of the mass distribution d M / d E for the debris ejected during the tidal disruption (with energy E ) and study their impact on jet power. Turbulence induced by tidal force and the self-gravity of the debris may imprint variabilities in d M / d E during fallback. We model these fluctuations with a power density spectrum \propto \,{f}_{{\rm{E}}}^{\beta } , where f E = 1/ E and β is the power-law index. We find that the resulting light curve can preserve the fluctuation characteristics from d M / d E . In addition, the observed fluctuations in the light curves can be reproduced for a given suitable β . Based on the observations, we find that the value of β should be around −1.}, archive = {J_ApJ}, author = {Yun-Peng Li and Da-Bin Lin and Guo-Yu Li and Zi-Min Zhou and En-Wei Liang}, doi = {10.3847/1538-4357/add3ff}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {195}, shortjournal = {The Astrophys. J.}, title = {Variabilities of gamma-ray bursts from the dynamics of fallback material after tidal disruption}, volume = {985}, year = {2025}, }
• (2025). Traversing the star-forming main sequence with molecular gas stacks of z ∼ 1.6 cluster galaxies. ApJ, 985(2), 194. (www)

  @article{ , abstract = {The cluster environment has been shown to affect the molecular gas content of cluster members, yet a complete understanding of this often subtle effect has been hindered due to a lack of detections over the full parameter space of galaxy star formation rates (SFRs) and stellar masses. Here, we stack CO(2–1) spectra of z ∼ 1.6 cluster galaxies to explore the average molecular gas fractions of galaxies both at lower mass (log( M * / M ⊙ ) ∼ 9.6) and further below the star-forming main sequence (SFMS; ΔMS ∼ −0.9) than other literature studies; this translates to a 3 σ gas mass limit of  ∼7 × 10 9 M ⊙ for stacked galaxies below the SFMS. We divide our sample of 54 z ∼ 1.6 cluster galaxies, derived from the Spitzer Adaptation of the Red-Sequence Cluster Survey, into nine groupings, for which we recover detections in 8. The average gas content of the full cluster galaxy population is similar to coeval field galaxies matched in stellar mass and SFR. However, when further split by CO-undetected and CO-detected, we find that galaxies below the SFMS have statistically different gas fractions from the field scaling relations, spanning deficiencies to enhancements from 2 σ below to 3 σ above the expected field gas fractions, respectively. These differences between z = 1.6 cluster and field galaxies below the SFMS are likely due to environmental processes, though further investigation of spatially resolved properties and more robust field scaling relation calibration in this parameter space are required.}, archive = {J_ApJ}, author = {Alex Pigarelli and Allison Noble and Gregory Rudnick and William Cramer and Stacey Alberts and Yannick Bahe and Patrick S. Kamieneski and Sebastian Montaño and Adam Muzzin and Julie Nantais and Sarah Saavedra and Eelco van Kampen and Tracy Webb and Christina C. Williams and Gillian Wilson and H. K. C. Yee}, doi = {10.3847/1538-4357/adc99e}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {194}, shortjournal = {The Astrophys. J.}, title = {Traversing the star-forming main sequence with molecular gas stacks of z ∼ 1.6 cluster galaxies}, volume = {985}, year = {2025}, }
• (2025). Formation of near-surface atmospheric inversion and surface inversion in hothouse climates. ApJ, 985(2), 193. (www)

  @article{ , abstract = {A hothouse climate may develop throughout Earth's history and its warming future, and on potentially habitable exoplanets near the inner edge of the habitable zone. Previous studies have suggested that near-surface atmospheric inversion (NAIV), with the planetary boundary air temperature being higher than the air temperature adjacent to the surface, is a pronounced phenomenon in hothouse climates. However, the underlying mechanisms are unclear. Here, we show that lower-tropospheric radiative heating is necessary but not independently sufficient in forming the NAIV. Instead, the dynamic heating induced by large-scale subsidence is essential. With the prescribed reasonable large-scale subsidence, NAIV appears in small-domain cloud-resolving simulations, which was not observed in previous studies. Surface evaporative cooling also contributes to the formation of the NAIV. Besides NAIV, we find that surface inversion (SIV), with the air adjacent to the surface being warmer than the underlying sea surface, is also a distinct phenomenon in hothouse climates. SIV is caused by strong surface evaporative cooling and large atmospheric shortwave absorption. These two types of inversion strongly stabilize the atmosphere, weaken atmospheric circulation, dry the free troposphere, and suppress the hydrological cycle.}, archive = {J_ApJ}, author = {Jiachen Liu and Feng Ding and Jun Yang}, doi = {10.3847/1538-4357/adca3c}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {193}, shortjournal = {The Astrophys. J.}, title = {Formation of near-surface atmospheric inversion and surface inversion in hothouse climates}, volume = {985}, year = {2025}, }
• (2025). Search for continuous gravitational waves from unknown neutron stars in binary systems with long orbital periods in o3 data. ApJ, 985(2), 192. (www)

  @article{ , abstract = {Gravitational waves emitted by asymmetric rotating neutron stars are the primary targets of continuous gravitational-wave searches. Neutron stars in binary systems are particularly interesting due to the potential for nonaxisymmetric deformations induced by a companion star. However, all-sky searches for unknown neutron stars in binary systems are very computationally expensive, and this limits their sensitivity and/or breadth. In this paper we present results of a search for signals with gravitational-wave frequencies between 50 and 150 Hz, from systems with orbital periods between 100 and 1000 days and projected semimajor axes between 40 and 200 lt-s. This parameter space region has never been directly searched before. We do not detect any signal, and our results exclude gravitational-wave amplitudes above 1.25 × 10 −25 at 144.32 Hz with 95% confidence. Our improved search pipeline is more sensitive than any previous all-sky binary search by about 75%.}, archive = {J_ApJ}, author = {P. B. Covas and M. A. Papa and R. Prix}, doi = {10.3847/1538-4357/adcc2b}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {192}, shortjournal = {The Astrophys. J.}, title = {Search for continuous gravitational waves from unknown neutron stars in binary systems with long orbital periods in o3 data}, volume = {985}, year = {2025}, }
• (2025). Ground to dust: Collisional cascades and the fate of kardashev II megaswarms. ApJ, 985(2), 191. (www)

  @article{ , abstract = {Extraterrestrial intelligences are speculated to surround stars with structures to collect their energy or to signal distant observers. If they exist, these most likely are megaswarms, vast constellations of satellites (elements) in orbit around the hosts. Although long-lived megaswarms are extremely powerful technosignatures, they are liable to be subject to collisional cascades once guidance systems start failing. The collisional time is roughly an orbital period divided by the covering fraction of the swarm. Structuring the swarm orbits does not prolong the initial collisional time as long as there is enough randomness to ensure collisions, although it can reduce collision velocities. I further show that once the collisional cascade begins, it can develop extremely rapidly for hypervelocity collisions. Companion stars or planets in the stellar system induce perturbations through the Lidov–Kozai effect among others, which can result in orbits crossing within some millions of years. Radiative perturbations, including the Yarkovsky effect, also can destabilize swarms. Most megaswarms are thus likely to be short-lived on cosmic timescales without active upkeep. I discuss possible mitigation strategies and implications for megastructure searches.}, archive = {J_ApJ}, author = {Brian C. Lacki}, doi = {10.3847/1538-4357/adccc5}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {191}, shortjournal = {The Astrophys. J.}, title = {Ground to dust: Collisional cascades and the fate of kardashev II megaswarms}, volume = {985}, year = {2025}, }
• (2025). The sun’s Open–Closed flux boundary and the origin of the slow solar wind. ApJ, 985(2), 190. (www)

  @article{ , abstract = {The Sun's open–closed flux boundary (OCB) separates closed and open magnetic field lines, and is the site for interchange magnetic reconnection processes thought to be linked to the origin of the slow solar wind (SSW). We analyze the global magnetic field structure and OCB from 2010 December to 2019 December using three coronal magnetic field models: a potential-field source-surface (PFSS) model, a static equilibrium magnetofrictional model, and a time-dependent magnetofrictional model. We analyze the model and cycle dependence of the OCB length on the photosphere, as well as the magnetic flux in the vicinity of the OCB. Near solar maximum, the coronal magnetic field for each model consists predominantly of long, narrow coronal holes, and nearly all the open flux lies within 1 supergranule diameter (25 Mm) of the OCB. By comparing to interplanetary scintillation measurements of SSW speeds, we argue that the fraction of open flux within this 25 Mm band is a good predictor of the amount of SSW in the heliosphere. Importantly, despite its simplicity, we show that the PFSS model estimates this fraction as well as the time-dependent model. We discuss the implications of our results for understanding SSW origins and interchange reconnection at the OCB.}, archive = {J_ApJ}, author = {Chloe P. Wilkins and David I. Pontin and Anthony R. Yeates and Spiro K. Antiochos and Hannah Schunker and Bishnu Lamichhane}, doi = {10.3847/1538-4357/adcd65}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {190}, shortjournal = {The Astrophys. J.}, title = {The sun’s Open–Closed flux boundary and the origin of the slow solar wind}, volume = {985}, year = {2025}, }
• (2025). A multimechanism hybrid model of peaked-spectrum radio sources. ApJ, 985(2), 189. (www)

  @article{ , abstract = {Peaked-spectrum (PS) sources exhibit turnover characteristics in their broad radio spectra. However, the mechanism underlying this phenomenon remains elusive. The two most common hypotheses are synchrotron self-absorption (SSA) and free–free absorption (FFA). By incorporating multiple absorption scenarios, we propose a multimechanism hybrid model, which aligns well with current observational data and provides a good physical explanation. Using data from the GLEAM survey, we identified a sample of 4315 sources with peak frequencies between approximately 72 and 3000 MHz, most of which are MHz-peaked-spectrum sources. Our analysis shows that FFA rather than SSA is the dominant mechanism in producing the spectral turnover for most of the sources in this sample. The index of the optically thick spectrum α thick has a lower boundary due to FFA, and the steeper α thick indicates a complex multiabsorption mechanism. In particular, the external FFA produces substantial α thick , which exhibits a weak correlation with the peak frequency. Future ultralong-wavelength observations would also provide data on the spectrum of these sources at even lower frequencies. Determining the absorption mechanism that shaped the spectrum of these sources would be a crucial part of understanding their nature.}, archive = {J_ApJ}, author = {Guang-Chen Sun and Yichao Li and Furen Deng and Yanping Cong and Fangxia An and Jiajun Zhang and Yougang Wang and Xin Zhang and Xuelei Chen}, doi = {10.3847/1538-4357/adcd75}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {189}, shortjournal = {The Astrophys. J.}, title = {A multimechanism hybrid model of peaked-spectrum radio sources}, volume = {985}, year = {2025}, }
• (2025). Viewing global changes in the heliosheath with IMAP’s energetic neutral atom imagers. ApJ, 985(2), 188. (www)

  @article{ , abstract = {We present a simulation analysis of NASA's upcoming Interstellar Mapping and Acceleration Probe (IMAP) energetic neutral atom (ENA) instrument capabilities in viewing "global" changes in the heliosheath (HS) plasma, and the resulting ENA flux changes detected near Earth. This is done by simulating ENA emissions produced by charge exchange in a simulated heliosphere, utilizing the instruments' energy coverage, and calculating the time it takes for the SW to travel from 1 au to the HS and for ENAs to travel back. We aim to answer the following: (i) What are the time delays as a function of energy and direction; (ii) at what energies can we observe changes the soonest; and (iii) what might the ENA source distributions affecting the time delays look like? We find the following: (i) The time delay depends on energy and direction in the sky, taking from >20 yr to <2 yr to see a response. The time delay does not decrease monotonically with increasing ENA energy, because of the energy-dependent, H+p charge exchange cross section. (ii) The quickest changes can be observed at ∼15 keV (without HS energy diffusion), intersecting IMAP-Hi and IMAP-Ultra energies. (iii) The ENA source distributions, and how far out IMAP can "see" the heliosphere, strongly depend on energy: IMAP-Lo and IMAP-Ultra should be able to view the farthest back in the heliotail but with long delay times. Finally, we show how energy diffusion in the HS affects the time delays and ENA source distributions, increasing ENA fluxes and prolonging time delays.}, archive = {J_ApJ}, author = {E. J. Zirnstein and J. Heerikhuisen and D. J. McComas and J. Bower and G. Clark and M. A. Dayeh and H. O. Funsten and M. Gkioulidou and D. G. Mitchell and D. B. Reisenfeld and N. A. Schwadron}, doi = {10.3847/1538-4357/adceb4}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {188}, shortjournal = {The Astrophys. J.}, title = {Viewing global changes in the heliosheath with IMAP’s energetic neutral atom imagers}, volume = {985}, year = {2025}, }
• (2025). Deciphering sub-neptune atmospheres: New insights from geochemical models of TOI-270 d. ApJ, 985(2), 187. (www)

  @article{ , abstract = {The nature of sub-Neptunes is one of the hottest topics in exoplanetary science. Temperate sub-Neptunes are of special interest because some could be habitable. Here, we consider whether these planets might instead be rocky worlds with thick, hot atmospheres. Can recent James Webb Space Telescope observations of TOI-270 d be understood in terms of such a model? We perform thermochemical equilibrium calculations to infer conditions of quenching of C–H–O–N species. Our results indicate apparent CO 2 –CH 4 equilibrium between ∼900 and ∼1100 K. The CO abundance should be quenched higher in the atmosphere where the equilibrium CO/CO 2 ratio is lower, potentially explaining a lack of CO. N 2 is predicted to dominate the nitrogen budget. We confirm that the atmosphere of TOI-270 d is strongly enriched in both C and O gas relative to protosolar H, whereas N is likely to be less enriched or even depleted. We attempt to reproduce these enrichments by modeling the atmosphere as nebular gas that extracted heavy elements from accreted solids. This type of model can explain the C/H and O gas /H ratios, but despite supersolar C/N ratios provided by solids, the NH 3 abundance will probably be too high unless there is a nitrogen sink in addition to N 2 . A magma ocean may be implied, and indeed the oxygen fugacity of the deep atmosphere seems sufficiently low to support the sequestration of reduced N in silicate melt. The evaluation presented here demonstrates that exoplanetary geochemistry now approaches a level of sophistication comparable to that achieved within our own solar system.}, archive = {J_ApJ}, author = {Christopher R. Glein and Xinting Yu and Cindy N. Luu}, doi = {10.3847/1538-4357/adced4}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {187}, shortjournal = {The Astrophys. J.}, title = {Deciphering sub-neptune atmospheres: New insights from geochemical models of TOI-270 d}, volume = {985}, year = {2025}, }
• (2025). The magnetic keys to massive star formation: The western η carinae giant molecular cloud. ApJ, 985(2), 186. (www)

  @article{ , abstract = {We present SOFIA/HAWC+ continuum polarization data on the magnetic fields ( B fields) threading 17 pc-scale massive molecular clumps at the western end of the η Carinae giant molecular cloud (Region 9 of the Galactic Census of High- and Medium-mass Protostars, or CHaMP, representing all stages of star formation from pre-stellar to dispersing via feedback), revealing important details about the field morphology and role in the gas structures of this clump sample. We performed Davis–Chandrasekhar–Fermi (DCF) and histogram of relative orientation (HRO) analyses tracing column densities 25.0 < log( N /m −2 ) < 27.2. With HRO, B fields change from mostly parallel to column density structures to mostly perpendicular at a threshold N crit = (3.7 ± 0.6) × 10 26 m −2 , indicating that gravitational forces exceed magnetic forces above this value. The same analysis in 10 individual clumps gives similar results, with the same clear trend in alignments and a threshold N crit = (1.9 {}_{-0.8}^{+1.5} ) × 10 26 m −2 . In the other seven clumps, the alignment trend with N is much flatter or even reversed, inconsistent with the usual HRO pattern. Instead, these clumps' fields reflect external environmental forces from the nearby H ii region NGC 3324. DCF analysis reveals field strengths somewhat higher than typical of nearby clouds, with the B–n data lying mostly above the R. M. Crutcher relation. The mass-to-flux ratio λ across all clumps has a Gaussian distribution, log λ DCF = –0.75 ± 0.45; only small areas are dominated by gravity. However, a significant trend of rising log λ with falling T dust parallels R. L. Pitts et al.'s result: T dust falls as {N{}_{{\rm{H}}}}_{2} rises toward clump centres. In this massive clump sample, B fields provide enough support against gravity to explain their overall low star formation rate.}, archive = {J_ApJ}, author = {Peter J. Barnes and Stuart D. Ryder and Giles Novak and Laura M. Fissel}, doi = {10.3847/1538-4357/adcedf}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {186}, shortjournal = {The Astrophys. J.}, title = {The magnetic keys to massive star formation: The western η carinae giant molecular cloud}, volume = {985}, year = {2025}, }
• (2025). A sandwich model for changing-look active galactic nuclei. ApJ, 985(2), 185. (www)

  @article{ , abstract = {The spectral variability of changing-look active galactic nuclei (CL-AGNs) occurred on timescales of years to tens of years, posing a significant challenge to the standard thin disk model. In this work, we propose a sandwich model, including an optically thick disk in the mid-plane (Disk 1) and two disks of low effective optical depth on both sides (Disk 2). These two types of disks are coupled with magnetic fields, which allow viscous torque interaction between them. As a consequence, the radial velocity of Disk 1 can increase by up to 3 orders of magnitude compared to the standard thin disk, leading to an equivalent decrease in the accretion timescale. Therefore, such a sandwich model can account for the rapid variability in CL-AGNs. In addition, we also discuss the influence of the magnetic pressure on Disk 2. When Disk 2 is dominated by the magnetic pressure, it resembles a "warm corona," which is responsible for the soft X-ray excess.}, archive = {J_ApJ}, author = {Qian-Qi Ma and Wei-Min Gu and Zhen-Yi Cai and Xinwu Cao and Jun-Xian Wang and Zhi-Xiang Zhang and Mouyuan Sun}, doi = {10.3847/1538-4357/add346}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {185}, shortjournal = {The Astrophys. J.}, title = {A sandwich model for changing-look active galactic nuclei}, volume = {985}, year = {2025}, }
• (2025). Modeling the ages and chemical abundances of elliptical galaxies. ApJ, 985(2), 184. (www)

  @article{ , abstract = {Spectroscopic studies of elliptical galaxies show that their stellar population ages, mean metallicity, and α enhancement traced by [Mg/Fe] all increase with galaxy stellar mass or velocity dispersion. We use one-zone galactic chemical evolution (GCE) models with a flexible star formation history (SFH) to model the age, [Mg/H], and [Mg/Fe] inferred from simple stellar population (SSP) fits to observed ellipticals at z ∼ 0 and z ∼ 0.7. We show that an SSP fit to the spectrum computed from a full GCE model gives ages and abundances close to the light-weighted, logarithmically averaged values of the composite stellar population, 〈age〉, 〈[Mg/H]〉, and 〈[Mg/Fe]〉. With supernova Mg and Fe yields fixed to values motivated by Milky Way stellar populations, we find that predicted 〈[Mg/H]〉–〈age〉 and 〈[Mg/Fe]〉–〈age〉 relations are surprisingly insensitive to SFH parameters: Older galaxies have higher 〈[Mg/Fe]〉, but the detailed form of the SFH has limited impact. The star formation efficiency (SFE) and outflow efficiency affect the early and late evolution of 〈[Mg/H]〉, respectively; explaining observed trends requires higher SFE and lower outflows in more massive galaxies. With core-collapse supernova yields calibrated to the plateau [Mg/Fe] cc ≈ 0.45 observed in many Milky Way studies, our models underpredict the observed 〈[Mg/Fe]〉 ratios of ellipticals by 0.05–0.1 dex. Increasing the core-collapse yield ratio to [Mg/Fe] cc = 0.55 improves the agreement, though the models remain below the data. We discuss potential resolutions of this discrepancy, including the possibility that many ellipticals terminate their star formation with a self-enriching, terminating burst that reduces the light-weighted age and boosts 〈[Mg/Fe]〉.}, archive = {J_ApJ}, author = {Nicole Marcelina Gountanis and David H. Weinberg and Aliza G. Beverage and Nathan R. Sandford and Charlie Conroy and Mariska Kriek}, doi = {10.3847/1538-4357/adc4e6}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {184}, shortjournal = {The Astrophys. J.}, title = {Modeling the ages and chemical abundances of elliptical galaxies}, volume = {985}, year = {2025}, }
• (2025). Search for gravitational waves emitted from SN 2023ixf. ApJ, 985(2), 183. (www)

  @article{ , abstract = {We present the results of a search for gravitational-wave transients associated with core-collapse supernova SN 2023ixf, which was observed in the galaxy Messier 101 via optical emission on 2023 May 19, during the LIGO–Virgo–KAGRA 15th Engineering Run. We define a five-day on-source window during which an accompanying gravitational-wave signal may have occurred. No gravitational waves have been identified in data when at least two gravitational-wave observatories were operating, which covered ∼14% of this five-day window. We report the search detection efficiency for various possible gravitational-wave emission models. Considering the distance to M101 (6.7 Mpc), we derive constraints on the gravitational-wave emission mechanism of core-collapse supernovae across a broad frequency spectrum, ranging from 50 Hz to 2 kHz, where we assume the gravitational-wave emission occurred when coincident data are available in the on-source window. Considering an ellipsoid model for a rotating proto-neutron star, our search is sensitive to gravitational-wave energy 1 × 10 −4 M ⊙ c 2 and luminosity 2.6 × 10 −4 M ⊙ c 2 s −1 for a source emitting at 82 Hz. These constraints are around an order of magnitude more stringent than those obtained so far with gravitational-wave data. The constraint on the ellipticity of the proto-neutron star that is formed is as low as 1.08, at frequencies above 1200 Hz, surpassing past results.}, archive = {J_ApJ}, author = {A. G. Abac and R. Abbott and I. Abouelfettouh and F. Acernese and K. Ackley and S. Adhicary and N. Adhikari and R. X. Adhikari and V. K. Adkins and D. Agarwal and M. Agathos and M. Aghaei Abchouyeh and O. D. Aguiar and I. Aguilar and L. Aiello and A. Ain and T. Akutsu and S. Albanesi and R. A. Alfaidi and A. Al-Jodah and C. Alléné and A. Allocca and S. Al-Shammari and P. A. Altin and S. Alvarez-Lopez and A. Amato and L. Amez-Droz and A. Amorosi and C. Amra and A. Ananyeva and S. B. Anderson and W. G. Anderson and M. Andia and M. Ando and T. Andrade and N. Andres and M. Andrés-Carcasona and T. Andrić and J. Anglin and S. Ansoldi and J. M. Antelis and S. Antier and M. Aoumi and E. Z. Appavuravther and S. Appert and S. K. Apple and K. Arai and A. Araya and M. C. Araya and J. S. Areeda and L. Argianas and N. Aritomi and F. Armato and N. Arnaud and M. Arogeti and S. M. Aronson and G. Ashton and Y. Aso and M. Assiduo and S. Assis de Souza Melo and S. M. Aston and P. Astone and F. Attadio and F. Aubin and K. AultONeal and G. Avallone and S. Babak and F. Badaracco and C. Badger and S. Bae and S. Bagnasco and E. Bagui and J. G. Baier and L. Baiotti and R. Bajpai and T. Baka and M. Ball and G. Ballardin and S. W. Ballmer and S. Banagiri and B. Banerjee and D. Bankar and P. Baral and J. C. Barayoga and B. C. Barish and D. Barker and P. Barneo and F. Barone and B. Barr and L. Barsotti and M. Barsuglia and D. Barta and A. M. Bartoletti and M. A. Barton and I. Bartos and S. Basak and A. Basalaev and R. Bassiri and A. Basti and D. E. Bates and M. Bawaj and P. Baxi and J. C. Bayley and A. C. Baylor and P. A. Baynard II and M. Bazzan and V. M. Bedakihale and F. Beirnaert and M. Bejger and D. Belardinelli and A. S. Bell and V. Benedetto and W. Benoit and J. D. Bentley and M. Ben Yaala and S. Bera and M. Berbel and F. Bergamin and B. K. Berger and S. Bernuzzi and M. Beroiz and D. Bersanetti and A. Bertolini and J. Betzwieser and D. Beveridge and N. Bevins and R. Bhandare and U. Bhardwaj and R. Bhatt and D. Bhattacharjee and S. Bhaumik and S. Bhowmick and A. Bianchi and I. A. Bilenko and G. Billingsley and A. Binetti and S. Bini and O. Birnholtz and S. Biscoveanu and A. Bisht and M. Bitossi and M.-A. Bizouard and J. K. Blackburn and L. A. Blagg and C. D. Blair and D. G. Blair and F. Bobba and N. Bode and G. Boileau and M. Boldrini and G. N. Bolingbroke and A. Bolliand and L. D. Bonavena and R. Bondarescu and F. Bondu and E. Bonilla and M. S. Bonilla and A. Bonino and R. Bonnand and P. Booker and A. Borchers and V. Boschi and S. Bose and V. Bossilkov and V. Boudart and A. Boudon and A. Bozzi and C. Bradaschia and P. R. Brady and M. Braglia and A. Branch and M. Branchesi and J. Brandt and I. Braun and M. Breschi and T. Briant and A. Brillet and M. Brinkmann and P. Brockill and E. Brockmueller and A. F. Brooks and B. C. Brown and D. D. Brown and M. L. Brozzetti and S. Brunett and G. Bruno and R. Bruntz and J. Bryant and F. Bucci and J. Buchanan and O. Bulashenko and T. Bulik and H. J. Bulten and A. Buonanno and K. Burtnyk and R. Buscicchio and D. Buskulic and C. Buy and R. L. Byer and G. S. Cabourn Davies and G. Cabras and R. Cabrita and V. Cáceres-Barbosa and L. Cadonati and G. Cagnoli and C. Cahillane and J. Calderón Bustillo and T. A. Callister and E. Calloni and J. B. Camp and M. Canepa and G. Caneva Santoro and K. C. Cannon and H. Cao and L. A. Capistran and E. Capocasa and E. Capote and G. Carapella and F. Carbognani and M. Carlassara and J. B. Carlin and M. Carpinelli and G. Carrillo and J. J. Carter and G. Carullo and J. Casanueva Diaz and C. Casentini and S. Y. Castro-Lucas and S. Caudill and M. Cavaglià and R. Cavalieri and G. Cella and P. Cerdá-Durán and E. Cesarini and W. Chaibi and P. Chakraborty and S. Chalathadka Subrahmanya and J. C. L. Chan and M. Chan and K. Chandra and R.-J. Chang and S. Chao and E. L. Charlton and P. Charlton and E. Chassande-Mottin and C. Chatterjee and Debarati Chatterjee and Deep Chatterjee and M. Chaturvedi and S. Chaty and A. Chen and A. H.-Y. Chen and D. Chen and H. Chen and H. Y. Chen and J. Chen and K. H. Chen and Y. Chen and Yanbei Chen and Yitian Chen and H. P. Cheng and P. Chessa and H. T. Cheung and S. Y. Cheung and F. Chiadini and G. Chiarini and R. Chierici and A. Chincarini and M. L. Chiofalo and A. Chiummo and C. Chou and S. Choudhary and N. Christensen and S. S. Y. Chua and P. Chugh and G. Ciani and P. Ciecielag and M. Cieślar and M. Cifaldi and R. Ciolfi and F. Clara and J. A. Clark and J. Clarke and T. A. Clarke and P. Clearwater and S. Clesse and E. Coccia and E. Codazzo and P.-F. Cohadon and S. Colace and M. Colleoni and C. G. Collette and J. Collins and S. Colloms and A. Colombo and M. Colpi and C. M. Compton and G. Connolly and L. Conti and T. R. Corbitt and I. Cordero-Carrión and S. Corezzi and N. J. Cornish and A. Corsi and S. Cortese and C. A. Costa and R. Cottingham and M. W. Coughlin and A. Couineaux and J.-P. Coulon and S. T. Countryman and J.-F. Coupechoux and P. Couvares and D. M. Coward and M. J. Cowart and R. Coyne and K. Craig and R. Creed and J. D. E. Creighton and T. D. Creighton and P. Cremonese and A. W. Criswell and J. C. G. Crockett-Gray and S. Crook and R. Crouch and J. Csizmazia and J. R. Cudell and T. J. Cullen and A. Cumming and E. Cuoco and M. Cusinato and P. Dabadie and T. Dal Canton and S. Dall’Osso and S. Dal Pra and G. Dálya and B. D’Angelo and S. Danilishin and S. D’Antonio and K. Danzmann and K. E. Darroch and L. P. Dartez and A. Dasgupta and S. Datta and V. Dattilo and A. Daumas and N. Davari and I. Dave and A. Davenport and M. Davier and T. F. Davies and D. Davis and L. Davis and M. C. Davis and P. J. Davis and M. Dax and J. De Bolle and M. Deenadayalan and J. Degallaix and M. De Laurentis and S. Deléglise and F. De Lillo and D. Dell’Aquila and W. Del Pozzo and F. De Marco and F. De Matteis and V. D’Emilio and N. Demos and T. Dent and A. Depasse and N. DePergola and R. De Pietri and R. De Rosa and C. De Rossi and R. DeSalvo and R. De Simone and A. Dhani and R. Diab and M. C. Díaz and M. Di Cesare and G. Dideron and N. A. Didio and T. Dietrich and L. Di Fiore and C. Di Fronzo and M. Di Giovanni and T. Di Girolamo and D. Diksha and A. Di Michele and J. Ding and S. Di Pace and I. Di Palma and F. Di Renzo and Divyajyoti and A. Dmitriev and Z. Doctor and E. Dohmen and P. P. Doleva and D. Dominguez and L. D’Onofrio and F. Donovan and K. L. Dooley and T. Dooney and S. Doravari and O. Dorosh and M. Drago and J. C. Driggers and J.-G. Ducoin and L. Dunn and U. Dupletsa and D. D’Urso and H. Duval and P.-A. Duverne and S. E. Dwyer and C. Eassa and M. Ebersold and T. Eckhardt and G. Eddolls and B. Edelman and T. B. Edo and O. Edy and A. Effler and J. Eichholz and H. Einsle and M. Eisenmann and R. A. Eisenstein and A. Ejlli and R. M. Eleveld and M. Emma and K. Endo and A. J. Engl and E. Enloe and L. Errico and R. C. Essick and H. Estellés and D. Estevez and T. Etzel and M. Evans and T. Evstafyeva and B. E. Ewing and J. M. Ezquiaga and F. Fabrizi and F. Faedi and V. Fafone and S. Fairhurst and A. M. Farah and B. Farr and W. M. Farr and G. Favaro and M. Favata and M. Fays and M. Fazio and J. Feicht and M. M. Fejer and R. Felicetti and E. Fenyvesi and D. L. Ferguson and S. Ferraiuolo and I. Ferrante and T. A. Ferreira and F. Fidecaro and P. Figura and A. Fiori and I. Fiori and M. Fishbach and R. P. Fisher and R. Fittipaldi and V. Fiumara and R. Flaminio and S. M. Fleischer and L. S. Fleming and E. Floden and E. M. Foley and H. Fong and J. A. Font and B. Fornal and P. W. F. Forsyth and K. Franceschetti and N. Franchini and S. Frasca and F. Frasconi and A. Frattale Mascioli and Z. Frei and A. Freise and O. Freitas and R. Frey and W. Frischhertz and P. Fritschel and V. V. Frolov and G. G. Fronzé and M. Fuentes-Garcia and S. Fujii and T. Fujimori and P. Fulda and M. Fyffe and B. Gadre and J. R. Gair and S. Galaudage and V. Galdi and H. Gallagher and S. Gallardo and B. Gallego and R. Gamba and A. Gamboa and D. Ganapathy and A. Ganguly and B. Garaventa and J. García-Bellido and C. García-Quirós and J. W. Gardner and K. A. Gardner and J. Gargiulo and A. Garron and F. Garufi and C. Gasbarra and B. Gateley and V. Gayathri and G. Gemme and A. Gennai and V. Gennari and J. George and R. George and O. Gerberding and L. Gergely and Archisman Ghosh and Sayantan Ghosh and Shaon Ghosh and Shrobana Ghosh and Suprovo Ghosh and Tathagata Ghosh and L. Giacoppo and J. A. Giaime and K. D. Giardina and D. R. Gibson and D. T. Gibson and C. Gier and P. Giri and F. Gissi and S. Gkaitatzis and J. Glanzer and F. Glotin and J. Godfrey and P. Godwin and N. L. Goebbels and E. Goetz and J. Golomb and S. Gomez Lopez and B. Goncharov and Y. Gong and G. González and P. Goodarzi and S. Goode and A. W. Goodwin-Jones and M. Gosselin and A. S. Göttel and R. Gouaty and D. W. Gould and K. Govorkova and S. Goyal and B. Grace and A. Grado and V. Graham and A. E. Granados and M. Granata and V. Granata and S. Gras and P. Grassia and A. Gray and C. Gray and R. Gray and G. Greco and A. C. Green and S. M. Green and S. R. Green and A. M. Gretarsson and E. M. Gretarsson and D. Griffith and W. L. Griffiths and H. L. Griggs and G. Grignani and A. Grimaldi and C. Grimaud and H. Grote and D. Guerra and D. Guetta and G. M. Guidi and A. R. Guimaraes and H. K. Gulati and F. Gulminelli and A. M. Gunny and H. Guo and W. Guo and Y. Guo and Anchal Gupta and Anuradha Gupta and Ish Gupta and N. C. Gupta and P. Gupta and S. K. Gupta and T. Gupta and N. Gupte and J. Gurs and N. Gutierrez and F. Guzman and H.-Y. H and D. Haba and M. Haberland and S. Haino and E. D. Hall and E. Z. Hamilton and G. Hammond and W.-B. Han and M. Haney and J. Hanks and C. Hanna and M. D. Hannam and O. A. Hannuksela and A. G. Hanselman and H. Hansen and J. Hanson and R. Harada and A. R. Hardison and K. Haris and T. Harmark and J. Harms and G. M. Harry and I. W. Harry and J. Hart and B. Haskell and C.-J. Haster and J. S. Hathaway and K. Haughian and H. Hayakawa and K. Hayama and R. Hayes and A. Heffernan and A. Heidmann and M. C. Heintze and J. Heinze and J. Heinzel and H. Heitmann and F. Hellman and P. Hello and A. F. Helmling-Cornell and G. Hemming and O. Henderson-Sapir and M. Hendry and I. S. Heng and E. Hennes and C. Henshaw and T. Hertog and M. 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J.}, title = {Search for gravitational waves emitted from SN 2023ixf}, volume = {985}, year = {2025}, }
• (2025). The Chicago–Carnegie hubble program: The JWST J-region asymptotic giant branch extragalactic distance scale*. ApJ, 985(2), 182. (www)

  @article{ , abstract = {The J-region asymptotic giant branch (JAGB) method is a new standard candle based on the constant luminosities of carbon-rich AGB stars in the J band. The JAGB method is independent of the Cepheid and tip of the red giant branch (TRGB) distance indicators. Therefore, we can leverage it to both cross-check Cepheid and TRGB distances for systematic errors and use it to measure an independent local H 0 . The JAGB method also boasts a number of advantages in measuring distances relative to the TRGB and Cepheids, several of which are especially amplified when combined with JWST's revolutionary resolving power. First, JAGB stars are 1 mag brighter in the near-IR (NIR) than the TRGB and can be discovered from single-epoch NIR photometry, unlike Cepheids, which require congruent optical imaging in at least 12 epochs. Thus, JAGB stars can be used to measure significantly farther distances than both the TRGB stars and Cepheids using the same amount of observing time. Dust extinction is also reduced in NIR observations and JAGB stars are ubiquitous in all galaxies with intermediate-age populations. We present a novel algorithm that identifies the optimal location in a galaxy for applying the JAGB method, so as to minimize the effects from crowding. We then deploy this algorithm in JWST NIRCam imaging of seven SN Ia host galaxies, to measure their JAGB distances, undertaking a completely blind analysis. In our Chicago–Carnegie Hubble Program H 0 results paper, by W. L. Freedman et al., we apply the JAGB distances measured in this paper to the Carnegie Supernova Program type Ia supernova sample, measuring a Hubble constant of H 0 = 67.80 ±2.17 (stat) ± 1.64 (sys) km s −1 Mpc −1 .}, archive = {J_ApJ}, author = {Abigail J. Lee and Wendy L. Freedman and Barry F. Madore and In Sung Jang and Kayla A. Owens and Taylor J. Hoyt}, doi = {10.3847/1538-4357/adc8a1}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {182}, shortjournal = {The Astrophys. J.}, title = {The Chicago–Carnegie hubble program: The JWST J-region asymptotic giant branch extragalactic distance scale*}, volume = {985}, year = {2025}, }
• (2025). The abundance and properties of barred galaxies out to z ∼ 4 using JWST CEERS data. ApJ, 985(2), 181. (www)

  @article{ , abstract = {We present the first estimate of the observed fraction and properties of bars out to z ∼ 4 using JWST CEERS NIRCam images. We analyze 1770 galaxies with M ⋆ > 10 10 M ⊙ at 0.5 ≤ z ≤ 4 and identify barred galaxies from 839 moderately inclined disk galaxies via ellipse fits and visual classification of both F200W and F444W images. Our results apply mainly to bars with projected semimajor axis a bar > 1.5 kpc (∼2 × point-spread function in F200W images) that can be robustly traced by ellipse fits. For such bars, the observed bar fraction at z ∼ 2–4 is low (≲10%), and they appear to be emerging at least as early as z ∼ 4. Our observed bar fraction at z ∼ 0.5–4 is consistent with the bar fraction predicted by TNG50 simulations for large bars with a bar >  1.5 kpc at z ∼ 0.5–4 and with the bar fraction from Auriga simulations out to z ∼ 1.5. However, TNG50 simulations predict a large population of smaller bars that our data cannot robustly detect. If such bars exist, the true bar fraction at z ∼ 2–4 may be significantly higher than our results. At z ≥ 1.5, many barred galaxies show nearby neighbors, suggesting bars may be tidally triggered. From z ∼ 4 to 0.5, the observed bar fraction, average projected bar length, and projected bar strength rise. Our results highlight the early emergence and evolution of barred galaxies and the rising importance of bar-driven secular evolution from z ∼ 4 to today.}, archive = {J_ApJ}, author = {Yuchen Guo and Shardha Jogee and Eden Wise and Keith Pritchett and Elizabeth J. McGrath and Steven L. Finkelstein and Kartheik G. Iyer and Pablo Arrabal Haro and Micaela B. Bagley and Mark Dickinson and Jeyhan S. Kartaltepe and Anton M. Koekemoer and Casey Papovich and Nor Pirzkal and L. Y. Aaron Yung and Bren E. Backhaus and Eric F. Bell and Rachana Bhatawdekar and Yingjie Cheng and Luca Costantin and Alexander de la Vega and Mauro Giavalisco and Nimish P. Hathi and Benne W. Holwerda and Peter Kurczynski and Ray A. Lucas and Bahram Mobasher and Pablo G. Pérez-González and Fabio Pacucci}, doi = {10.3847/1538-4357/adc8a7}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {181}, shortjournal = {The Astrophys. J.}, title = {The abundance and properties of barred galaxies out to z ∼ 4 using JWST CEERS data}, volume = {985}, year = {2025}, }
• (2025). Constraints on the evolution of an overluminous blue supergiant from its parent open cluster, vdBH 245. ApJ, 985(2), 180. (www)

  @article{ , abstract = {In this paper, we constrain the properties of an overluminous blue supergiant star (BSG) in the open cluster vdBH 245. We confirm the cluster membership of a sample of early-to-mid B-type stars using their proper motions, parallaxes, and radial velocities. We measure the stellar parameters through a spectrophotometric analysis of their optical spectra and near-infrared photometry. We correct for the effects of extinction of the cluster's light and estimate a most likely age range for vdBH 245 of 31.6 {}_{-13.8}^{+13.1} Myr using the Binary Population and Spectral Synthesis (or BPASS) Python software hoki and models from the Geneva group. We find a distance of 2.0 ± 0.2 kpc for the cluster, consistent with the value estimated by Gaia of 2.6 ± 0.5 kpc. However, the new age estimate does not agree with previous studies that have found much younger ages. We find that single-star evolution alone is unable to explain the BSG in that age range, even when considering the impact of rotation on stellar evolution. Instead, we find that the overluminous B8–B9 Ia BSG could be interpreted as a merger between two stars with initial masses ranging from 8.5–12.0 M ⊙ and 1.1–10.8 M ⊙ , with a current mass in the range of 13.4–20.6 M ⊙ . The merger would have occurred somewhere between 5.0 and 21.0 Myr after the cluster's formation. The discovery of such a BSG appearing too young (≈10 Myr in the single-star paradigm) for its population hints at the importance of considering binary interactions to explain the observed population of Galactic BSGs.}, archive = {J_ApJ}, author = {Alexandre Legault and Nicole St-Louis and André-Nicolas Chené and Fabrice Martins and Anthony Hervé and Leigh C. Smith and Karla Peña Ramírez and Sebastian Ramírez Alegría and Kaimi Kahihikolo}, doi = {10.3847/1538-4357/adc90d}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {180}, shortjournal = {The Astrophys. J.}, title = {Constraints on the evolution of an overluminous blue supergiant from its parent open cluster, vdBH 245}, volume = {985}, year = {2025}, }
• (2025). The high-redshift blazar MG3 j163554+3629: Physical properties and the enigma of its unexpected supermassive black hole growth. ApJ, 985(2), 179. (www)

  @article{ , abstract = {There is general consensus that active galactic nuclei (AGNs) derive their radiating power from a supermassive black hole (SMBH) that accretes matter. Yet, their precise powering mechanisms and the resulting growth of the SMBH are poorly understood, especially for AGNs at high redshift. Blazars are AGNs pointing their jet toward the observer, thus being detectable from radio through gamma rays at high redshift due to Doppler boosting. The blazar MG3 J163554+3629 is located at redshift z = 3.65 and it is a flat spectrum radio quasar (FSRQ). In this work, we show the results of the modeling of its spectral energy distribution (SED) from radio to gamma rays with a one-zone leptonic model. We estimate the uncertainties through a Markov Chain Monte Carlo approach. As a result, we infer the black hole mass {M}_{{\rm{B}}{\rm{H}}}=1.{1}_{-0.1}^{+0.2}\times 1{0}^{9}{M}_{\odot } and a modest magnetic field of B=6.5{6}_{-0.09}^{+0.13}\times 1{0}^{-2}\,{\rm{G}} in line with the Compton dominance observed in high-redshift FSRQs. The emitting region is outside the broad line region but within the region of the dust torus radius. The rather small accretion efficiency of η = 0.083 is not solely inferred through the SED modeling but also through the energetics. An evolution study suggests that in an Eddington-limited accretion process the SMBH did not have time enough to grow from an initial seed mass of  ∼10 6 M ⊙ at z ≈ 30 into a mass of M BH ≈ 10 9 M ⊙ at z = 3.65. Faster mass growth might be obtained in a super-Eddington process throughout frequent episodes. Alternative scenarios propose that the existence of the jet itself can facilitate a more rapid growth.}, archive = {J_ApJ}, author = {Jose Maria Sanchez Zaballa and Eugenio Bottacini and Andrea Tramacere}, doi = {10.3847/1538-4357/adc994}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {179}, shortjournal = {The Astrophys. J.}, title = {The high-redshift blazar MG3 j163554+3629: Physical properties and the enigma of its unexpected supermassive black hole growth}, volume = {985}, year = {2025}, }
• (2025). MACER3D—An upgrade of MACER2D with enhanced subgrid models and gas physics—and its application to simulating AGN feedback in a massive elliptical galaxy. ApJ, 985(2), 178. (www)

  @article{ , abstract = {We present Multiscale AGN-regulated Cosmic Ecosystem Resolver in 3D (MACER3D), a new suite of three-dimensional hydrodynamic simulations that study active galactic nuclei (AGN) feedback on galactic scales over gigayears in duration, with major enhancements in subgrid models and gas physics over its predecessor—Massive AGN Controlled Ellipticals Resolved (MACER), which is in two dimensions (hereafter MACER2D). MACER3D resolves gas dynamics from within the Bondi radius (∼25 pc) to halo scales. Combined with black hole accretion theory, it enables an accurate calculation of AGN outputs and subsequently their large-scale feedback effects. We present results from simulating an isolated elliptical galaxy with different feedback configurations. In the fiducial model with both AGN and supernova (SN) feedback, the temporal evolution of AGN luminosity and star formation rate are strongly correlated, suggesting shared dependence on the availability of gas supply for SMBH accretion and star formation. AGN duty cycles of several percent with a single-cycle timescale of ∼10 2 Myr agree with observations, while models with only AGN or SN feedback fail to reproduce observed cycles. While all models maintain a quiescent galaxy state, the fiducial AGN+SN feedback model results in higher star formation than no-SN feedback, suggesting SN feedback, when acting synergistically with AGN feedback, may positively impact star formation. Combined AGN and SN feedback enhances halo-scale metal enrichment compared to single-feedback models. The simulated X-ray properties match observations and predict transient cavities produced by cold-mode AGN winds from past burst events. The differences between the results obtained by MACER2D and MACER3D are also discussed.}, archive = {J_ApJ}, author = {Haoen Zhang and Haojie Xia and Suoqing Ji and Feng Yuan and Minhang Guo and Rui Zhang and Bocheng Zhu and Yihuan Di and Aoyun He and Tingfang Su and Yuxuan Zou}, doi = {10.3847/1538-4357/adcaba}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {178}, shortjournal = {The Astrophys. J.}, title = {MACER3D—An upgrade of MACER2D with enhanced subgrid models and gas physics—and its application to simulating AGN feedback in a massive elliptical galaxy}, volume = {985}, year = {2025}, }
• (2025). Comparing optical variability of type 1 and type 2 AGN from the BAT 9 month sample using ASAS-SN and TESS surveys. ApJ, 985(2), 177. (www)

  @article{ , abstract = {We present an optical variability analysis and comparison of the samples of Seyfert 1 (Sy1) and Seyfert 2 (Sy2) galaxies, selected from the Swift 9 month BAT catalog, using the light curves from Transiting Exoplanet Survey Satellite (TESS) and All-Sky Automated Survey for SuperNovae (ASAS-SN). We measured the normalized excess variance of TESS and ASAS-SN light curves for each target and performed a Kolmogorov–Smirnov test between the two samples, where our results showed significant differences. This is consistent with predictions from the unification model, where Seyfert 2s are obscured by the larger scale dust torus and their variability is suppressed. This variability difference is independent of the luminosity, Eddington ratio, or black hole mass, further supporting geometrical unification models. We searched the dependence of the normalized excess variance of Sy1s on absolute magnitudes, Eddington ratio, and black hole mass, where our results are consistent with relations found in the literature. Finally, a small subsample of changing-look (CL) active galactic nuclei (AGNs) that transitioned during the time frame of the ASAS-SN light curves, with their variability amplitudes changing according to the classification, have larger variability as type 1s and smaller as 2s. The change of variability amplitudes can be used to better pinpoint when the type transition occurred. The consistency trend of the variability amplitude differences between Sy1s and Sy2s and between CL AGNs in 1 or 2 stages suggests that variability can be a key factor in shedding light on the CL AGN or the dichotomy between Sy1 or Sy2 populations.}, archive = {J_ApJ}, author = {Natalie Kovacevic and Xinyu Dai and Heechan Yuk and Emilia E. Järvelä and Tingfeng Yi and Patrick J. Vallely and Benjamin J. Shappee and Francesco Shankar and K. Z. Stanek}, doi = {10.3847/1538-4357/adcb40}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {177}, shortjournal = {The Astrophys. J.}, title = {Comparing optical variability of type 1 and type 2 AGN from the BAT 9 month sample using ASAS-SN and TESS surveys}, volume = {985}, year = {2025}, }
• (2025). Periodic low-amplitude radial velocity variations in the supergiant α persei. ApJ, 985(2), 176. (www)

  @article{ , abstract = {α Per (HD 20902) is one of the brightest F5 supergiants, located at the blue edge of the instability strip. Several studies reported ∼100 day periods in the radial velocity (RV) variations in α Per, but the reported periods and amplitudes were all different, and the origins of these periodic RV variations remained unknown. We obtained 884 spectra for α Per from 2005 to 2020 using the Bohyunsan Observatory Echelle Spectrograph. We found a significant 130.6 day period in RV variations in the generalized Lomb–Scargle periodogram. In addition, the primary 130.6 day period has changed into 66.0 days during the observational duration. The line bisectors, stellar activity indices, such as Ca ii H & K lines and H α equivalent widths, and Hipparcos photometric data were analyzed to establish the origins and the periodicity change of the RV variations. We found ∼130 day periods in line bisector variations, which also changed into ∼66 days as in RV variations, with a time delay of ∼400 days leading the RV variations. Either nonradial oscillations or rotational modulation of surface features can affect both RV and line bisector variations. However, nonradial oscillations are more likely to be the origin of RV variations in α Per, considering the characteristics of the periodogram of RV variations. The change of the periodicities and the time delay between RV and line bisector variations as observed in this work may provide interesting clues to the ongoing physical processes in α Per.}, archive = {J_ApJ}, author = {Tae-Yang Bang and Byeong-Cheol Lee and Yeon-Ho Choi and Inwoo Han and Myeong-Gu Park}, doi = {10.3847/1538-4357/adcc13}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {176}, shortjournal = {The Astrophys. J.}, title = {Periodic low-amplitude radial velocity variations in the supergiant α persei}, volume = {985}, year = {2025}, }
• (2025). The first systematically identified repeating partial tidal disruption event. ApJ, 985(2), 175. (www)

  @article{ , abstract = {Tidal disruption events (TDEs) occur when a star enters the tidal radius of a supermassive black hole. If the star only grazes the tidal radius, a fraction of the stellar mass will be accreted in a partial TDE (pTDE). The remainder can continue orbiting and may be redisrupted at pericenter, causing a repeating pTDE. pTDEs may be as or more common than full TDEs, yet few are known. In this work, we present the discovery of the first repeating pTDE from a systematically selected sample, AT 2020vdq. AT 2020vdq was originally identified as an optically and radio-flaring TDE. Around 947 days after its discovery, it rebrightened dramatically in the optical. The optical flare was remarkably fast and luminous given its black hole mass compared to previous TDEs. It was accompanied by extremely broad (∼0.1 c ) optical/UV spectral features and faint X-ray emission ( L X ∼ 3 × 10 41 erg s −1 ), but no new radio-emitting component. Based on the transient optical/UV spectral features and the broadband lightcurve, we show that AT 2020vdq is a repeating pTDE. We then use it to constrain TDE models; in particular, we favor a star originally in a very tight binary system that is tidally broken apart by the Hills mechanism. We also constrain the repeating pTDE rate to be 10 −6 –10 −5 yr −1 galaxy −1 , with uncertainties dominated by the unknown distribution of pTDE repeat timescales. In the Hills framework, this means the binary fraction in the galactic nucleus is of the order of a few percent.}, archive = {J_ApJ}, author = {Jean J. Somalwar and Vikram Ravi and Yuhan Yao and Muryel Guolo and Matthew Graham and Erica Hammerstein and Wenbin Lu and Matt Nicholl and Yashvi Sharma and Robert Stein and Sjoert van Velzen and Eric C. Bellm and Michael W. Coughlin and Steven L. Groom and Frank J. Masci and Reed Riddle}, doi = {10.3847/1538-4357/adcc19}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {175}, shortjournal = {The Astrophys. J.}, title = {The first systematically identified repeating partial tidal disruption event}, volume = {985}, year = {2025}, }
• (2025). Galaxy rest-frame UV colors at z ∼ 2–4 with HST UVCANDELS. ApJ, 985(2), 174. (www)

  @article{ , abstract = {We present an analysis of rest-frame ultraviolet (UV) colors of 17,243 galaxies at z ∼ 2–4 in the Hubble Space Telescope UVCANDELS fields: GOODS-N, GOODS-S, COSMOS, and EGS. Here, we study the rest-frame UV spectral slope, β , measured via model spectra obtained via spectral energy distribution (SED) fitting, β SED , and explore its correlation with various galaxy parameters—photometric redshift, UV magnitude, stellar mass, dust attenuation, star formation rate (SFR), and specific SFR—obtained via SED fitting with Dense Basis . We also obtain measurements for β via photometric power-law fitting and compare them to our SED-fit-based results, finding good agreement on average. While we find little evolution in β with redshift from z = 2–4 for the full population, there are clear correlations between β (and related parameters) when binned by stellar mass. For this sample, lower-stellar-mass galaxies (log[ M * ] = 7.5–8.5 M ⊙ ) are typically bluer ( {\beta }_{{\rm{SED}}}=-2.{0}_{-0.2}^{+0.2} / {\beta }_{{\rm{PL}}}=-2.{1}_{-0.4}^{+0.4} ), fainter ( {M}_{{\rm{UV}}}=-17.{8}_{-0.6}^{+0.7} ), and less dusty ( {A}_{{\rm{v}}}=0.{4}_{-0.1}^{+0.1} mag), and they exhibit lower rates of star formation (log[SFR]= 0.{1}_{-0.2}^{+0.2}{M}_{\odot }\,{{\rm{yr}}}^{-1} ) and higher specific star formation rates (log[sSFR] = -8.{2}_{-0.2}^{+0.2}\,{{\rm{yr}}}^{-1} ) than their high-mass counterparts. Higher-mass galaxies (log[ M * ] = 10.0–12.0 M ⊙ ) are on average redder ( {\beta }_{{\rm{SED}}}=-0.{9}_{-0.5}^{+0.8} / {\beta }_{{\rm{PL}}}=-1.{0}_{-0.5}^{+0.8} ), brighter ( {M}_{{\rm{UV}}}=-19.{6}_{-1.2}^{+1.0} ), and dustier ( {A}_{{\rm{v}}}=0.{9}_{-0.4}^{+0.5} mag), and they have higher SFRs (log[SFR] = 1.{2}_{-1.1}^{+0.6}{M}_{\odot }\,{{\rm{yr}}}^{-1} ) and lower sSFRs (log[sSFR] = -9.{1}_{-1.1}^{+0.5}\,{{\rm{yr}}}^{-1} ). This study's substantial sample size provides a benchmark for demonstrating that the rest-frame UV spectral slope correlates with stellar-mass-dependent galaxy characteristics at z ∼ 2–4, a relationship less discernible with the smaller data sets typically available at higher redshifts.}, archive = {J_ApJ}, author = {Alexa M. Morales and Steven L. Finkelstein and Micaela B. Bagley and Anahita Alavi and Norman A. Grogin and Nimish P. Hathi and Anton M. Koekemoer and Kalina V. Nedkova and Laura Prichard and Marc Rafelski and Ben Sunnquist and Sina Taamoli and Harry I. Teplitz and Xin Wang and Rogier A. Windhorst and L. Y. Aaron Yung}, doi = {10.3847/1538-4357/adcc1d}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {174}, shortjournal = {The Astrophys. J.}, title = {Galaxy rest-frame UV colors at z ∼ 2–4 with HST UVCANDELS}, volume = {985}, year = {2025}, }
• (2025). Gotta go fast: A generalization of the escape speed to fluid-dynamical explosions and implications for astrophysical transients. ApJ, 985(2), 173. (www)

  @article{ , abstract = {A star's ability to explode in a core-collapse supernova is correlated with its density profile, ρ ( r ), such that compact stars with shallow density profiles preferentially "fail" and produce black holes. This correlation can be understood from a mass perspective, as shallower density profiles enclose ∼3 M ⊙ (i.e., the maximum neutron-star mass) at relatively small radii, but could also be due to the fact that a shockwave (driving the explosion) inevitably stalls if the density profile into which it propagates is shallower than ρ ( r ) ∝ r −2 . Here, we show that this condition—the density profile being steeper than ρ ∝ r −2 —is necessary, but not sufficient, for generating a strong explosion. In particular, we find solutions to the fluid equations that describe a shockwave propagating at a fixed fraction of the local freefall speed into a temporally evolving, infalling medium, the density profile of which scales as ρ ∝ r − n at large radii. The speed of the shock diverges as n → 2 and declines (eventually to below the Keplerian escape speed) as n increases, while the total energy contained in the explosion approaches zero as the shock recedes to large distances. These solutions therefore represent fluid-dynamical analogs of marginally bound orbits, and yield the "shock escape speed" as a function of the density profile. We also suggest that stellar explodability is correlated with the power-law index of the density at ∼10 9 cm, where the neutrino diffusion time equals the local dynamical time for most massive stars, which agrees with supernova simulations.}, archive = {J_ApJ}, author = {Daniel A. Paradiso and Eric R. Coughlin}, doi = {10.3847/1538-4357/adce6f}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {173}, shortjournal = {The Astrophys. J.}, title = {Gotta go fast: A generalization of the escape speed to fluid-dynamical explosions and implications for astrophysical transients}, volume = {985}, year = {2025}, }
• (2025). Hydrogen-poor superluminous supernovae with bumpy light curves powered by precessing magnetars. ApJ, 985(2), 172. (www)

  @article{ , abstract = {Recent observations and statistical studies have revealed that a significant fraction of hydrogen-poor superluminous supernovae (SLSNe-I) exhibit light curves that deviate from the smooth evolution predicted by the magnetar-powered model, instead showing one or more bumps after the primary peak. However, the formation mechanisms of these postpeak bumps remain a matter of debate. Furthermore, previous studies employing the magnetar-powered model have typically assumed a fixed magnetic inclination angle and neglected the effects of magnetar precession. However, recent research has shown that the precession of newborn magnetars forming during the collapse of massive stars causes the magnetic inclination angle to evolve over time, thereby influencing magnetic dipole radiation. In this paper, therefore, we incorporate the effects of magnetar precession into the magnetar-powered model to develop the precessing magnetar-powered model. Using this model, we successfully reproduce the multiband light curves of six selected representative SLSNe-I with postpeak bumps. Moreover, the derived model parameters fall within the typical parameter range for SLSNe-I. By combining the precessing magnetars in SLSNe-I and long gamma-ray bursts, we find that the ellipticity of magnetars is related to the dipole magnetic field strength, which may suggest a common origin for the two phenomena. Our work provides a potential explanation for the origin of postpeak bumps in SLSNe-I and offers evidence for the early precession of newborn magnetars formed in supernova explosions.}, archive = {J_ApJ}, author = {Biao Zhang and Long Li and Zi-Gao Dai and Shu-Qing Zhong}, doi = {10.3847/1538-4357/adceb3}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {172}, shortjournal = {The Astrophys. J.}, title = {Hydrogen-poor superluminous supernovae with bumpy light curves powered by precessing magnetars}, volume = {985}, year = {2025}, }
• (2025). Probing the kinematics of multiple- and single-protostar systems in perseus with N2H+. ApJ, 985(2), 171. (www)

  @article{ , abstract = {We analyze the dense gas kinematics in two class 0/I protostellar cores, Per 30 and NGC 1333 IRAS 7, in the Perseus Molecular Cloud to determine whether their velocity structures are indicative of rotation. We examine the hyperfine structure of the N 2 H + J = 1–0 transition by combining 3'' (900 au) Atacama Large Millimeter/submillimeter Array measurements with 9'' (2700 au) measurements from the Green Bank Telescope. We use the CASA Feather method to combine these data in order to maximize our sensitivity across spatial scales. We fit the N 2 H + spectra to constrain the centroid velocity of the gas at each pixel and use these values to calculate the linear velocity gradient and specific angular momentum within apertures centered on each protostar with radii ranging from 5'' to 60''. Our results indicate that the velocity structure probed by the N 2 H + emission is likely not a result of core rotation. These findings are consistent with other studies in the literature that indicate rotation is often not evident on scales ≲1000 au. We instead suggest that the velocity structure we see is a result of torques caused by irregular density distributions in these protostellar systems.}, archive = {J_ApJ}, author = {Erica Behrens and Adele Plunkett and Zhi-Yun Li}, doi = {10.3847/1538-4357/adcebd}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {171}, shortjournal = {The Astrophys. J.}, title = {Probing the kinematics of multiple- and single-protostar systems in perseus with N2H+}, volume = {985}, year = {2025}, }
• (2025). Impacts of tidal locking on magnetospheric energy input to exoplanet atmospheres. ApJ, 985(2), 170. (www)

  @article{ , abstract = {We investigate the effect of planetary corotation on energy dissipation within the magnetosphere–ionosphere system of exoplanets. Using magnetohydrodynamic simulations, we find that tidally locked exoplanets have a higher cross polar cap potential (CPCP) compared to fast-rotating planets with the same magnetic field strength, confirming previous studies. Our simulations show that for a given interplanetary magnetic field, an increase in corotation period leads to a higher CPCP. Notably, this difference in CPCP between tidally locked and rotating planets persists across a range of solar wind conditions, including extreme environments such as those experienced by hot Jupiters. Furthermore, we observe that variations in corotation have little impact on CPCP for Earth-sized planets. These results underscore the significance of both corotation dynamics and planetary size in understanding how exoplanets interact with their stellar environments.}, archive = {J_ApJ}, author = {Fatemeh Bagheri and Alex Glocer and Ramon E. Lopez}, doi = {10.3847/1538-4357/adcec7}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {170}, shortjournal = {The Astrophys. J.}, title = {Impacts of tidal locking on magnetospheric energy input to exoplanet atmospheres}, volume = {985}, year = {2025}, }
• (2025). Exploring the active galactic nucleus fraction of a sample of JWST’s little red dots at 4 < z < 8: Overmassive black holes are strongly favored. ApJ, 985(2), 169. (www)

  @article{ , abstract = {JWST is revolutionizing our view of the early Universe by pushing the boundaries of detectable galaxies and black holes in redshift (upward) and mass (downward). The little red dots (LRDs), detected by several surveys at z > 4, present a significant interpretational challenge, as their spectral energy distributions (SEDs) can mimic both active galactic nucleus (AGN) and stellar population templates. This study analyzes 19 LRDs from the JWST Advanced Deep Extragalactic Survey survey, utilizing NIRCam and MIRI photometry. By performing SED fitting across a vast parameter space, we explore a broad range of AGN fractions, defined as the ratio of the monochromatic luminosities (AGN, galaxy, and dust) over a specified wavelength range, 0.4–0.7 μ m rest frame. We find that 17 of the 19 LRDs investigated are consistent with having significant AGN contributions, with best-fitting AGN fractions ranging between 20% and 70%, while one galaxy shows a low AGN contribution (2%) and another appears to be purely star forming. Moreover, assuming these LRDs do indeed host AGN, we can place limits on their black hole masses using the inferred AGN bolometric luminosities and adopting the Eddington limit. We find that, independent of the specific AGN fraction adopted, the LRDs' black holes are significantly overmassive relative to their host galaxies—by ∼1 dex, and up to ∼4 dex in the most extreme cases—compared to the local M • – M ⋆ relation. The presence of overmassive black holes in the high- z Universe may provide the strongest evidence yet of heavy black hole seeding occurring during the cosmic dark ages.}, archive = {J_ApJ}, author = {Emmanuel Durodola and Fabio Pacucci and Ryan C. Hickox}, doi = {10.3847/1538-4357/adced2}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {169}, shortjournal = {The Astrophys. J.}, title = {Exploring the active galactic nucleus fraction of a sample of JWST’s little red dots at 4 < z < 8: Overmassive black holes are strongly favored}, volume = {985}, year = {2025}, }
• (2025). Fundamental understanding of magnetic reconnection via spiral CT scan. III. electron agyrotropy and temperature anisotropy. ApJ, 985(2), 168. (www)

  @article{ , abstract = {For the first time, we reveal the distribution of electron agyrotropy and electron temperature anisotropy around a reconnection X-line by using the spiral CT scan technique, which is a novel technique analogous to that in the hospital. This X-line was detected by the Magnetospheric Multiscale (MMS) spacecraft and has been widely believed to host a magnetic reconnection without a guide field. With the help of such an advanced technique, we find that: (1) the electron agyrotropy is weak in the magnetosheath-side inflow region, medium in the magnetosphere-side inflow region, and strong near the X point; (2) the electron temperature is isotropic near the current sheet center but is parallel-dominant in both the magnetosheath-side and magnetosphere-side inflow regions, with the anisotropy on the magnetosphere side more prominent than on the magnetosheath side. Quantitatively, the strongest electron agyrotropy is within a scale of 10 km (0.1 d i ) around the X point. Interestingly, there is no enhancement of electron agyrotropy near the magnetosheath-side separatrix line. Both the electron agyrotropy and temperature anisotropy exhibit asymmetric distributions in the two inflow regions, providing different conditions for wave generation and instability growth, which may affect the reconnection rate.}, archive = {J_ApJ}, author = {H. S. Fu and Z. Wang and J. B. Cao}, doi = {10.3847/1538-4357/add0b3}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {168}, shortjournal = {The Astrophys. J.}, title = {Fundamental understanding of magnetic reconnection via spiral CT scan. III. electron agyrotropy and temperature anisotropy}, volume = {985}, year = {2025}, }
• (2025). Image instabilities and polarization crosstalk. ApJ, 985(2), 167. (www)

  @article{ , abstract = {We expand on our previous study of the impact of atmospheric seeing on polarization crosstalk, and show how the formalism that was developed in that work can be applied to treat the case of spatial modulators of polarization. Beside formally demonstrating how the problem of crosstalk is fully eliminated in such devices, we also gain insight on the meaning of polarimetric noise of temporal modulation schemes in the limit of very high modulation frequency. We also describe the problem of spectrograph instabilities, and how the spectral gradients that are naturally associated with a line spectrum feed into the problem of polarimetric errors induced by mechanical vibrations, thermal drifts, and pointing jitter. Finally, we show how this formalism can be used to estimate the contribution of polarization crosstalk to the errors on the elements of the 4 × 4 Stokes response matrix, for the purpose of producing realistic error budgets for polarimetric instrumentation.}, archive = {J_ApJ}, author = {R. Casini and A. G. de Wijn}, doi = {10.3847/1538-4357/adc68b}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {167}, shortjournal = {The Astrophys. J.}, title = {Image instabilities and polarization crosstalk}, volume = {985}, year = {2025}, }
• (2025). Early planet formation in embedded disks (eDisk). XXI. limited role of streamers in mass supply to the disk in the class 0 protostar IRAS 16544-1604. ApJ, 985(2), 166. (www)

  @article{ , abstract = {Asymmetric and narrow infalling structures, often called streamers, have been observed in several Class 0/I protostars, which is not expected in the classical star formation picture. Their origin and impact on the disk formation remain observationally unclear. By combining data from the James Clerk Maxwell Telescope (JCMT) and Atacama Large Millimeter/submillimeter Array (ALMA), we investigate the physical properties of the streamers and parental dense core in the Class 0 protostar, IRAS 16544–1604. Three prominent streamers associated to the disk with lengths between 2800 and 5800 au are identified on the northern side of the protostar in the C 18 O emission. Their mass and mass infalling rates are estimated to be in the range of (1–4) × 10 −3 M ⊙ and (1–5) × 10 −8 M ⊙ yr −1 , respectively. Infall signatures are also observed in the more diffuse extended protostellar envelope observed with the ALMA from the comparison to the infalling and rotating envelope model. The parental dense core detected by the JCMT observation has a mass of ∼0.5 M ⊙ , a subsonic to transonic turbulence of { \mathcal M } =  0.8–1.1, and a mass-to-flux ratio of 2–6. Our results show that the streamers in IRAS 16544–1604 only possess 2% of the entire dense core mass and contribute less than 10% of the mass infalling rate of the protostellar envelope. Therefore, the streamers in IRAS 16544–1604 play a minor role in the mass accretion process onto the disk, in contrast to those streamers observed in other sources and those formed in numerical simulations of collapsing dense cores with similar turbulence and magnetic field strengths.}, archive = {J_ApJ}, author = {Miyu Kido and Hsi-Wei Yen and Jinshi Sai and Shigehisa Takakuwa and Nagayoshi Ohashi and Yuri Aikawa and Yusuke Aso and Christian Flores and Ilseung Han and Patrick M. Koch and Woojin Kwon and Jeong-Eun Lee and Zhi-Yun Li and Leslie W. Looney and Mayank Narang and Kazuya Saigo and Rajeeb Sharma and Travis J. Thieme and Kengo Tomida and Jonathan P. Williams}, doi = {10.3847/1538-4357/adc72a}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {166}, shortjournal = {The Astrophys. J.}, title = {Early planet formation in embedded disks (eDisk). XXI. limited role of streamers in mass supply to the disk in the class 0 protostar IRAS 16544-1604}, volume = {985}, year = {2025}, }
• (2025). The EMPI code for plasma-induced effects on radio waves. i. nonmagnetized media and applications to fast radio bursts. ApJ, 985(2), 165. (www)

  @article{ , abstract = {Electromagnetic waves undergo modifications as they propagate through plasma. We present electromagnetic wave–plasma interaction (EMPI), a three-dimensional numerical framework designed to simulate the interaction between radio signals and cold plasma. With input plasma density profiles, intrinsic radio signals, and the time and frequency resolutions of the telescope, the code synthesizes observed signals using first-principles calculations. EMPI is capable of modeling a wide range of plasma distributions, spanning analytically described smooth functions (e.g., Gaussian or exponential profiles), statistical models (e.g., turbulent screens), and discrete macroscopic structures like isolated plasma clumps, which are difficult to model both analytically and statistically. Validation tests demonstrate excellent agreement with established plasma propagation effects, such as dispersion, lensing, scintillation, and scattering. This code provides an efficient method for handling both analytical and statistical scenarios, bridging the gap between these descriptions. Thanks to its comprehensive capabilities, EMPI is particularly useful for studying radio sources of cosmological origin, especially pulse-like signals such as fast radio bursts. As these signals travel through diverse and complex plasma environments across the universe, their properties are inevitably altered, resulting in observable changes. In this context, EMPI serves as a valuable tool for studying the propagation effects of these sources, helping to advance the understanding of their essence and the intervening plasma environments.}, archive = {J_ApJ}, author = {Nan Xu and He Gao and Yuan-Pei Yang and Bing Zhang and Wei-Yang Wang and Tian-Cong Wang and Ran Gao}, doi = {10.3847/1538-4357/adc92d}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {165}, shortjournal = {The Astrophys. J.}, title = {The EMPI code for plasma-induced effects on radio waves. i. nonmagnetized media and applications to fast radio bursts}, volume = {985}, year = {2025}, }
• (2025). The 230 GHz variability of numerical models of sagittarius a*. II. the physical origins of the variability. ApJ, 985(2), 164. (www)

  @article{ , abstract = {We continue our previous work, H.-S. Chan et al., to investigate how variations in the electron temperature prescription parameter, R Low , influence the 3 hr variability at 230 GHz, M Δ T , in magnetically arrested disk (MAD) models of Sagittarius A* (Sgr A*), through analyzing a series of general-relativistic magnetohydrodynamics and ray-tracing simulations. For models with a black hole spin a > 0, we discovered that increasing R Low renders the photon ring more optically thick, obscuring the varying accretion flows that contribute to the variability. However, as R Low increases further, MAD flux eruptions become more pronounced, compensating for the decrease in M Δ T . For models with spin a < 0, although a higher R Low also increases the optical thickness of the fluid, voids within the optically thick gas fail to cover the entire photon ring. Similarly, flux eruptions become more prominent as R Low increases further, contributing to the observed rise in M Δ T relative to R Low . For black holes with spin a = 0, although the effect of increasing optical depth is still present, their 230 GHz light curves, and hence M Δ T , are insensitive to changes in R Low . Furthermore, we found that the variability of the 230 GHz light curves at R Low = 1 might correlate with fluctuations in the internal energy of the gas near the black hole, and we listed potential causes and solutions to the over-variability problem. Our findings highlight potential approaches for refining M Δ T to better align with observations when modeling Sgr A*.}, archive = {J_ApJ}, author = {Ho-Sang Chan and Chi-kwan Chan}, doi = {10.3847/1538-4357/adc99f}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {164}, shortjournal = {The Astrophys. J.}, title = {The 230 GHz variability of numerical models of sagittarius a*. II. the physical origins of the variability}, volume = {985}, year = {2025}, }
• (2025). Simultaneous construction of fast equator, poleward meridional flow, and near-surface shear layer in solar magnetohydrodynamic calculation. ApJ, 985(2), 163. (www)

  @article{ , abstract = {We carry out an unprecedented high-resolution simulation for the solar convection zone. Our calculation reproduces the fast equator and near-surface shear layer (NSSL) of differential rotation and the near-surface poleward meridional flow simultaneously. The NSSL is located in a complex layer where the spatial and time scales of thermal convection are significantly small compared with the deep convection zone. While there have been several attempts to reproduce the NSSL in numerical simulation, the results are still far from reality. In this study, we succeed in reproducing an NSSL in our new calculation. Our analyses led to a deeper understanding of the construction mechanism of the NSSL, which is summarized as: (1) rotationally unconstrained convection in the near-surface layer transports the angular momentum radially inward; (2) sheared poleward meridional flow around the top boundary is constructed; (3) the shear causes a positive kinetic \langle {v}_{r}^{{\prime} }{v}_{\theta }^{{\prime} }\rangle and negative magnetic 〈 B r B θ 〉 correlations; and (4) the turbulent viscosity and magnetic tension are latitudinally balanced with the Coriolis force in the NSSL. We emphasize the importance of the magnetic field in the solar convection zone.}, archive = {J_ApJ}, author = {H. Hotta}, doi = {10.3847/1538-4357/adca3b}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {163}, shortjournal = {The Astrophys. J.}, title = {Simultaneous construction of fast equator, poleward meridional flow, and near-surface shear layer in solar magnetohydrodynamic calculation}, volume = {985}, year = {2025}, }
• (2025). Unraveling the mysteries of KS 1947+300: Multiwavelength observations in a low-eccentricity Be/X-ray binary. ApJ, 985(2), 162. (www)

  @article{ , abstract = {KS 1947+300, a Be/X-ray binary system, has been observed to experience both type I and type II X-ray outbursts despite its nearly circular orbit, which is atypical according to the viscous decretion disk model. To understand the variations in optical and X-ray, we have analyzed data covering more than 20 yr of observations. In the optical band, we analyzed spectra and light curves, measuring the strength of the H α and He i λ 6678 lines. In the X-ray band, we studied the long-term light curves provided by several all-sky monitors. KS 1947+300 exhibits changes in brightness and H α emission on timescales from months to years. The optical and IR variability shows small amplitude changes during the active X-ray state, and a long, smooth decrease during the quiescent state. The fact that the amplitude of variability increased with wavelength suggests that the long-term decrease in the optical emission is due to weakening of the circumstellar disk. Structural changes in the disk may also be the origin of the periodic signals with periods ∼200 days detected in the Zwicky Transient Facility (ZTF)- g and ZTF- r band light curves. These changes could be attributed to the mechanism that ejects matter from the photosphere of the Be star into the disk. In conclusion, the long-term changes in optical continuum and line emission, as well as the X-ray variability patterns, are attributed to an evolving and distorted decretion disk.}, archive = {J_ApJ}, author = {Wei Liu and Pablo Reig and Jingzhi Yan and Peng Zhang and Xiukun Li and Bo Gao and Guangcheng Xiao and Zhongmu Li and Qingzhong Liu}, doi = {10.3847/1538-4357/adcac3}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {162}, shortjournal = {The Astrophys. J.}, title = {Unraveling the mysteries of KS 1947+300: Multiwavelength observations in a low-eccentricity Be/X-ray binary}, volume = {985}, year = {2025}, }
• (2025). Structure and dynamics of erupting solar prominences using the rolling hough transform: Toward a feature-oriented classification. ApJ, 985(2), 161. (www)

  @article{ , abstract = {The classification of solar prominences has proven to be challenging, due to their diverse morphologies and dynamical behavior. Complexity is heightened when considering eruptive prominences, where the dynamics demand methods capable of capturing detailed structural information. While there exist a range of line-of-sight and plane-of-sky (POS) techniques that have advanced our understanding of prominence motions, they are subject to limitations, emphasizing the need for effective methods of extracting structural information from prominence dynamics. We present a proof of concept for the spatial Rolling Hough Transform (RHT) algorithm, which identifies fine-scale structural orientation in the POS, applied to prominence structure and dynamics. We demonstrate the RHT approach using two contrasting prominence dynamics events using Solar Dynamics Observatory/Atmospheric Imaging Assembly 304 Å observations: (1) a quiet-Sun eruption, and (2) activation (swirl) of a polar crown prominence. By analyzing the light curves and movies from each event, we divide the events into distinct dynamical phases: from slow rise to drainage. The spatial RHT method enables us to extract structural information and localized dynamics for both events and the different evolution phases. We develop a classification to label the prominences as either radially or tangentially oriented structures. The quiet-Sun eruption has a predominately tangential structure in the slow-rise phase but displays greater radial features during/after the eruption. The polar swirl activation initially shows a strong radial contribution, which diminishes as more tangential structures appear during/after the activation. Our results demonstrate the successful application of the spatial RHT to prominences, leading to the classification of individual prominences and an insight into their dynamics.}, archive = {J_ApJ}, author = {Harry Birch and Stéphane Régnier}, doi = {10.3847/1538-4357/adcba3}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {161}, shortjournal = {The Astrophys. J.}, title = {Structure and dynamics of erupting solar prominences using the rolling hough transform: Toward a feature-oriented classification}, volume = {985}, year = {2025}, }
• (2025). Narrowband imaging of a z = 3.24 protocluster: Insights from [O iii]-emitting galaxies. ApJ, 985(2), 160. (www)

  @article{ , abstract = {We present narrowband imaging of a spectroscopically confirmed protocluster "D4UD01" at z = 3.24 using CFHT/WIRCam. We identify a sample of 24 [O iii ] emission-line galaxies in the field, which forms a large overdensity in the protocluster region. The protocluster is expected to evolve into a Virgo-like cluster by z = 0. Utilizing multiwavelength data, we derive the physical properties of these [O iii ] emitters and find that they are intermediate-mass normal star-forming galaxies (∼10 10 M ⊙ ) roughly following the star-forming main sequence. The [O iii ] emitters trace an overdensity spatially offset from that of photometric-redshift and quiescent galaxies, suggesting that these distinct galaxy populations may inhabit dark matter halos that formed at different epochs. A comparative analysis of [O iii ]-emitter properties shows similar characteristics in both protocluster and field environments. This protocluster likely represents an evolved structure that has progressed beyond its peak star formation phase, although our limited sample size may prevent detection of subtle environmental effects.}, archive = {J_ApJ}, author = {Ke Shi and Jun Toshikawa and Xianzhong Zheng and Zheng Cai and Dongdong Shi}, doi = {10.3847/1538-4357/adce72}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {160}, shortjournal = {The Astrophys. J.}, title = {Narrowband imaging of a z = 3.24 protocluster: Insights from [O iii]-emitting galaxies}, volume = {985}, year = {2025}, }
• (2025). Physics of pair-producing gaps in black hole magnetospheres: Two-dimensional general relativistic particle-in-cell simulations. ApJ, 985(2), 159. (www)

  @article{ , abstract = {Black holes can launch powerful jets through the Blandford–Znajek process. This relies on enough plasma in the jet funnel to conduct the necessary current. However, in some low-luminosity active galactic nuclei, the plasma supply near the jet base may be an issue. It has been proposed that spark gaps—local regions with unscreened electric field—can form in the magnetosphere, accelerating particles to initiate pair cascades, thus filling the jet funnel with plasma. In this paper, we carry out 2D general relativistic particle-in-cell (GRPIC) simulations of the gap, including self-consistent treatment of inverse Compton scattering and pair production. We observe gap dynamics that is fully consistent with our earlier 1D GRPIC simulations. We find strong dependence of the gap power on the soft photon spectrum and energy density, as well as the strength of the horizon magnetic field. We derive physically motivated scaling relations, and applying to M87, we find that the gap may be energetically viable for the observed TeV flares. For Sgr A*, the energy dissipated in the gap may also be sufficient to power the X-ray flares.}, archive = {J_ApJ}, author = {Yajie Yuan and Alexander Y. Chen and Martin Luepker}, doi = {10.3847/1538-4357/adce79}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {159}, shortjournal = {The Astrophys. J.}, title = {Physics of pair-producing gaps in black hole magnetospheres: Two-dimensional general relativistic particle-in-cell simulations}, volume = {985}, year = {2025}, }
• (2025). Temporal variation of flare occurrence rates via the spot evolution on the sun and solar-type stars. ApJ, 985(2), 158. (www)

  @article{ , abstract = {The spot evolution on the Sun and solar-type stars is important for understanding the nature of consequential flaring activity. This study statistically investigates the variance of flare occurrence rate through the time evolution of spots on the Sun and solar-type stars. We have compiled the 28 yr catalogs of solar flares and their source sunspots obtained from solar surface observations by NOAA and GOES for the Sun. Also, we combined the cataloged stellar flares with the time evolution of starspots estimated by light curves obtained by the 4 yr Kepler mission for solar-type stars. For the obtained 24,124 solar flares and 180 stellar flares, we calculate the flare occurrence distribution with respect to {t}_{{\rm{flare}}}-{t}_{{\rm{\max }}} , which represents the timing of flare through the spot evolution, where {t}_{{\rm{flare}}} is the flare occurrence time and {t}_{{\rm{\max }}} is the time when the source spot takes its maximum area. When normalized by the spot lifetime, we found that the flare occurrence distribution for {t}_{{\rm{flare}}}-{t}_{{\rm{\max }}} shows a similar distribution regardless of spot size or flare energy, suggesting that the Sun and the solar-type star share the same physical process in the spot-to-flare activity. On this basis, we propose a formula for the time variation of the flare occurrence rate per spot. Also, the correlation between the temporal variation of flare occurrence rate and the time evolution of spot area and the lack of difference in flare occurrence rate between the emergence and decaying phases provide a milestone for the nature of flare-productive spots.}, archive = {J_ApJ}, author = {Takato Tokuno and Kosuke Namekata and Hiroyuki Maehara and Shin Toriumi}, doi = {10.3847/1538-4357/adce7c}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {158}, shortjournal = {The Astrophys. J.}, title = {Temporal variation of flare occurrence rates via the spot evolution on the sun and solar-type stars}, volume = {985}, year = {2025}, }
• (2025). Magnetic reconnection in a compact magnetic dome: Chromospheric emissions and high-velocity plasma flows. ApJ, 985(2), 157. (www)

  @article{ , abstract = {Magnetic reconnection at small spatial scales is a fundamental driver of energy release and plasma dynamics in the lower solar atmosphere. We present observations of a brightening in an active region, captured in high-resolution data from the Daniel K. Inouye Solar Telescope using the Visible Broadband Imager and the Visible Spectro-Polarimeter (ViSP). The event exhibits Ellerman bomb−like morphology in the H β filter, associated with flux cancellation between a small negative-polarity patch and an opposite polarity plage. Additionally, it displays enhanced emissions in Ca ii K, hot elongated features containing Alfvénic plasma flows, and cooler blueshifted structures. We employ multiline, nonlocal thermodynamic equilibrium inversions of the spectropolarimetric data to infer the stratification of the physical parameters of the atmosphere. Furthermore, we use the photospheric vector magnetogram inferred from the ViSP spectra as a boundary condition for nonlinear force-free field extrapolations, revealing the three-dimensional distribution of squashing factors. We find significant enhancements in temperature, velocity, and microturbulence confined to the upper photosphere and low chromosphere. Our findings provide observational evidence of low-altitude magnetic reconnection along quasi-separatrix layers in a compact fan-spine-type configuration, highlighting the complex interplay between magnetic topology, energy release, and plasma flows.}, archive = {J_ApJ}, author = {J. M. da Silva Santos and E. Dunnington and R. Jarolim and S. Danilovic and S. Criscuoli}, doi = {10.3847/1538-4357/adcf23}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {157}, shortjournal = {The Astrophys. J.}, title = {Magnetic reconnection in a compact magnetic dome: Chromospheric emissions and high-velocity plasma flows}, volume = {985}, year = {2025}, }
• (2025). Survivor bias in longitudinal asymmetry of impulsive solar energetic particle events. ApJ, 985(2), 156. (www)

  @article{ , abstract = {We follow H.-Q. He and W. Wan in studying the distribution of impulsive solar energetic particle (SEP) events from the updated observations. We confirm their findings of the longitudinal asymmetry of the distribution of SEPs with respect to the east side and west side of the magnetic footpoint, which is indicated as the "east–west azimuthal asymmetry." With a qualitative analysis, H.-Q. He and W. Wan suggested that this asymmetry is caused by perpendicular diffusion and heliospheric magnetic field structure. We use a simple probability-based statistical method to provide the distribution of SEP events as an analytical function of relative longitude. We find that the impulsive SEP events not correlated to observed flares were indeed flare-induced but went unobserved due to the flares occurring on the far side of the Sun. Furthermore, the observed east–west azimuthal asymmetry of SEPs is caused by the survivor bias.}, archive = {J_ApJ}, author = {G. Qin and L. Qiao and Y. Wang}, doi = {10.3847/1538-4357/adcf97}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {156}, shortjournal = {The Astrophys. J.}, title = {Survivor bias in longitudinal asymmetry of impulsive solar energetic particle events}, volume = {985}, year = {2025}, }
• (2025). Simulation study of optical band radiation during the afterglow phase of gamma-ray bursts based on the HADAR experiment. ApJ, 985(2), 155. (www)

  @article{ , abstract = {Studying the afterglow of gamma-ray bursts (GRBs) is essential for refining theoretical models, uncovering their underlying physical processes, and exploring potential new physics. Multiwavelength investigations have emerged as a fundamental approach for deciphering the complex nature of GRBs, harnessing the complementary observational capabilities of advanced spaceborne observatories and sophisticated ground-based facilities. The High Altitude Detection of Astronomical Radiation (HADAR) experiment utilizes a novel wide-angle atmospheric Cherenkov detection technology, offering the advantages of a wide field of view and a low energy threshold. It is capable of not only observing the very-high-energy (VHE) gamma radiation from GRBs but also conducting observational studies on the optical afterglow of GRBs. In this work, we simulated the expected observations of HADAR for the optical and VHE gamma radiation afterglow of GRB 190114C. The results indicate that HADAR can effectively observe both bands of this GRB, particularly demonstrating excellent sensitivity in the optical band and providing good imaging of its radiation process. This demonstrates that HADAR is capable of conducting effective observations and research on the optical radiation of similar GRBs. Its contributions can refine relevant theoretical research and may enable attempts to observe gravitational-wave counterparts.}, archive = {J_ApJ}, author = {Heng-Jiao Liu and Tian-Lu Chen and Yi-Qing Guo and Zi-Hao Zhang and Yu-Hua Yao and Cheng Liu and Qing-Yuan Hou and Qing-Qian Zhou and Mao-Yuan Liu and Qi Gao and Xiang-Li Qian and Jia-Dan Xie and Shan-Jie Shu and Yuan-Qi Liu and Wei-Qi Han and Shao-Hua Zhang and Ya-Nan Wang and Qi-Jiao Fang and Zhi-Qiang Zhu and Bao-Zhen Liu and You-Liang Feng}, doi = {10.3847/1538-4357/adcf99}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {155}, shortjournal = {The Astrophys. J.}, title = {Simulation study of optical band radiation during the afterglow phase of gamma-ray bursts based on the HADAR experiment}, volume = {985}, year = {2025}, }
• (2025). Inference of multichannel r-process element enrichment in the milky way using binary neutron star merger observations. ApJ, 985(2), 154. (www)

  @article{ , abstract = {Observations of GW170817 strongly suggest that binary neutron star (BNS) mergers produce rapid neutron-capture nucleosynthesis ( r -process) elements. However, it remains an open question whether these mergers can account for all the r -process element enrichment in the Milky Way's history. Here, we constrain the contributions of the BNS channel using astrophysical neutron star observations. The rate and mass distributions are constrained by LIGO/Virgo/Kagra through the latest catalog GWTC-3, the neutron star equation of state by gravitational-wave, radio, and X-ray observations, and the delay time distribution by short gamma-ray burst (GRB) host galaxy associations. We present a Bayesian framework to consistently combine these observations with abundance information to quantify the contribution and uncertainties of single and multiple astrophysical enrichment sources, and obtain a distribution of per-event BNS r -process element yields consistent with geophysical and astrophysical abundance constraints. We then adopt a Galactic chemical evolution model assuming an instantaneous and fixed amount of Fe enrichment from core-collapse supernovae, and show that BNS-only enrichment scenarios remain inconsistent with the observed r -process abundance trend of disk stars in the Galaxy even with the uncertainties in BNS merger observations. Using stellar abundance observations instead of the short GRB constraints, we can infer a shorter BNS delay time distribution with power-law index α ≤ −2.0 and minimum delay time {t}_{{\rm{\min }}}\leqslant 40 Myr at 90% confidence, consistent with detailed Galactic chemical evolution models. Such delay times are in tension with those predicted by standard BNS formation models. Alternatively, we confirm that a two-channel scenario, in which the second channel tracks the star formation history without significant delay, can account for both Galactic stellar and short GRB observations. We estimate that 45%–90% of the r -process abundance in the Milky Way today would have been produced by this star formation-tracking channel, rather than BNS mergers with significant delay times.}, archive = {J_ApJ}, author = {Hsin-Yu Chen and Philippe Landry and Jocelyn S. Read and Daniel M. Siegel}, doi = {10.3847/1538-4357/add0af}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {154}, shortjournal = {The Astrophys. J.}, title = {Inference of multichannel r-process element enrichment in the milky way using binary neutron star merger observations}, volume = {985}, year = {2025}, }
• (2025). Enhanced nuclear binding near the proton drip line opens possible bypass of the 64Ge rapid proton capture process waiting point. ApJ, 985(2), 153. (www)

  @article{ , abstract = {We performed astrophysics model calculations with updated nuclear data to identify a possible bypass of the 64 Ge waiting point, a defining feature of the rapid proton capture (rp) process that powers type I X-ray bursts on accreting neutron stars. We find that the rp-process flow through the 64 Ge bypass could be up to 36% for astrophysically relevant conditions. Our results call for new studies of 65 Se, including the nuclear mass, β -delayed proton emission branching, and nuclear structure as it pertains to the 64 As( p , γ ) reaction rate at X-ray burst temperatures.}, archive = {J_ApJ}, author = {Z. Meisel and W.-J. Ong and J. S. Randhawa}, doi = {10.3847/1538-4357/add260}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {153}, shortjournal = {The Astrophys. J.}, title = {Enhanced nuclear binding near the proton drip line opens possible bypass of the 64Ge rapid proton capture process waiting point}, volume = {985}, year = {2025}, }
• (2025). Atmospheric heating events associated with fine-scale flux emergence in ephemeral regions. ApJ, 985(2), 152. (www)

  @article{ , abstract = {Coronal heating has puzzled solar physicists for decades. The question of why the Sun's upper atmosphere is significantly hotter than its lower atmosphere remains a key mystery. It is commonly believed that the source of coronal heating comes from the Sun's magnetic field, and more complex magnetic dynamics are more efficient in heating. In an earlier work, we studied the secondary (or finer-scale) flux emergence identified in five ephemeral regions (ERs), selected during the last solar minimum. Here we further explore the atmospheric response to the secondary flux emergences (SFEs) that were identified in the first paper. We further reveal that approximately 80% of the 172 identified SFEs are associated with atmospheric heating events. The heating is most likely associated with magnetic reconnection involving the SFE. Overall, a solar quiet region is heated by several hundred thousand degrees during the flux emergence of an ER.}, archive = {J_ApJ}, author = {Hanlin Yang and Jingxiu Wang and Chunlan Jin}, doi = {10.3847/1538-4357/add2fc}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {152}, shortjournal = {The Astrophys. J.}, title = {Atmospheric heating events associated with fine-scale flux emergence in ephemeral regions}, volume = {985}, year = {2025}, }
• (2025). Toward a self-consistent hydrodynamical model of the solar tachocline. ApJ, 985(2), 151. (www)

  @article{ , abstract = {The solar tachocline is a thin internal boundary layer in the Sun located between the differentially rotating convection zone and the uniformly rotating region of the radiative interior beneath. E. A. Spiegel & J. P. Zahn proposed the first hydrodynamical model, which here we call SZ92, arguing that the tachocline is essentially in a steady state of thermal-wind balance, angular-momentum balance, and thermal equilibrium. Angular momentum transport in their model is assumed to be dominated by strongly anisotropic turbulence, which is primarily horizontal, owing to the strong stable stratification of the radiative interior. By contrast, the heat transport is assumed to be dominated by a predominantly vertical diffusive heat flux, owing to the thinness of the tachocline. In this paper, we demonstrate that these assumptions are not consistent with the new model of stratified turbulence recently proposed by G. P. Chini et al. and K. Shah et al., which has been numerically validated by P. Garaud et al. We then propose a simple self-consistent alternative to the SZ92 model—namely, a scenario wherein angular momentum and heat transport are both dominated by horizontal turbulent diffusion. The thickness of the tachocline in the new model scales as Ω ⊙ / N m , where Ω ⊙ is the mean angular velocity of the Sun and N m is the characteristic buoyancy frequency in the tachocline region. We discuss other properties of the model and show that it has several desirable features but does not resolve some of the other well-known problems of the SZ92 model.}, archive = {J_ApJ}, author = {P. Garaud and D. O. Gough and L. I. Matilsky}, doi = {10.3847/1538-4357/adc72b}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {151}, shortjournal = {The Astrophys. J.}, title = {Toward a self-consistent hydrodynamical model of the solar tachocline}, volume = {985}, year = {2025}, }
• (2025). A spectroscopic survey of metal-poor OB stars in local dwarf galaxy NGC 3109. ApJ, 985(2), 150. (www)

  @article{ , abstract = {As JWST uncovers increasingly strong evidence that metal-poor, massive stars in early galaxies dominated reionization, observational constraints on the properties of such stars are more relevant than ever before. However, spectra of individual O- and B-type stars are rare at the relevant metallicities (≲0.2 Z ⊙ ), leaving models of stellar evolution and ionizing flux poorly constrained by data in this regime. We present new medium-resolution ( R ∼ 4000) optical spectra of 17 OB stars in the local low-metallicity (0.12 Z ⊙ ) dwarf galaxy NGC 3109. We assign spectral types to the stars and present new criteria for selecting O stars using optical and near-UV photometry from Hubble Space Telescope imaging. We fit the spectra and photometry with grids of stellar atmosphere models to measure stellar temperatures, surface gravities, luminosities, radii, and masses. We find evidence of strong mass loss via radiation-driven stellar winds in two O stars, one of which is the hottest, youngest, and most massive star confirmed in the host galaxy to date. Though its spectrum does not meet conventional Wolf–Rayet spectral classification criteria, this metal-poor O5 If star produces strong He ii λ 4686 emission, and its evolutionary status is ambiguous. This work nearly doubles the number of OB stars with measured parameters in NGC 3109, including 12 stars with no previously reported parameters, five with no published spectroscopy, and four binary candidates. This large sample of OB stellar parameters provides a new observational testbed to constrain the stellar astrophysics that drove cosmic reionization and influenced the evolution of the earliest galaxies.}, archive = {J_ApJ}, author = {Abby Mintz and O. Grace Telford and Evan N. Kirby and John Chisholm and Kristen B. W. McQuinn and Danielle A. Berg}, doi = {10.3847/1538-4357/adc923}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {150}, shortjournal = {The Astrophys. J.}, title = {A spectroscopic survey of metal-poor OB stars in local dwarf galaxy NGC 3109}, volume = {985}, year = {2025}, }
• (2025). Polarimetric signatures of bulk comptonization from within the plunging region of accreting black holes. ApJ, 985(2), 149. (www)

  @article{ , abstract = {Inverse Compton scattering by the thermal motions of electrons is believed to produce polarized hard X-rays in active galactic nuclei and black hole binaries. Meanwhile, plasma within the plunging region of the black hole free-falls into the event horizon with a bulk relativistic speed, which could also imprint polarization on upscattered photons but has not been discussed in detail. To examine this, we computed polarimetric signatures via general relativistic ray tracing of a toy model consisting of an accreting, geometrically thin plasma with moderate optical depth, falling into the black hole with a bulk relativistic speed within the plunging region. We show that the maximum spatially unresolved linear polarization could be as large as approximately 7%–8% when the black hole is viewed near edge-on, while the corresponding resolved linear polarization could be roughly 50%. The large discrepancy between the two is due to (1) dilution from the radiation outside the plunging region and (2) substantial cancellations of the Stokes Q and U fluxes. The resultant polarization contributed by bulk Comptonization could nevertheless exceed that of thermal electron scattering in a Novikov–Thorne disk. Our results thus suggest a new model for imprinting considerable polarization on the electromagnetic observables of accreting black holes. Measurements of X-ray polarization from black hole binaries and the central black hole of active galactic nuclei could provide direct detection of the plunging region and help constrain plasma properties in the immediate vicinity of the event horizon.}, archive = {J_ApJ}, author = {Ho-Sang Chan and Mitchell C. Begelman and Jason Dexter}, doi = {10.3847/1538-4357/adc9a0}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {149}, shortjournal = {The Astrophys. J.}, title = {Polarimetric signatures of bulk comptonization from within the plunging region of accreting black holes}, volume = {985}, year = {2025}, }
• (2025). L1448 IRS3B: Dust polarization aligned with spiral features, tracing gas flows. ApJ, 985(2), 148. (www)

  @article{ , abstract = {Circumstellar disk dust polarization in the (sub)millimeter is, for the most part, not from dust grain alignment with magnetic fields but rather indicative of a combination of dust self-scattering with a yet unknown alignment mechanism that is consistent with mechanical alignment. While the observational evidence for scattering has been well established, that for mechanical alignment is less so. Circum-multiple dust structures in protostellar systems provide a unique environment to probe different polarization alignment mechanisms. We present ALMA Band 4 and Band 7 polarization observations toward the multiple young system L1448 IRS3B. The polarization in the two bands are consistent with each other, presenting multiple polarization morphologies. On the size scale of the inner envelope surrounding the circum-multiple disk, the polarization is consistent with magnetic field dust grain alignment. On the very small scale of compact circumstellar regions, we see polarization that is consistent with scattering around source a and c , which are likely the most optically thick components. Finally, we see polarization that is consistent with mechanical alignment of dust grains along the spiral dust structures, which would suggest that the dust is tracing the relative gas flow along the spiral arms. If the gas-flow dust grain alignment mechanism is dominant in these cases, disk dust polarization may provide a direct probe of the small-scale kinematics of the gas flow relative to the dust grains.}, archive = {J_ApJ}, author = {Leslie W. Looney and Zhe-Yu Daniel Lin and Zhi-Yun Li and John J. Tobin and Martin Radecki and Syzygy Butte and Ian W. Stephens and Manuel Fernández-López and Haifeng Yang and Nickalas K. Reynolds and Patrick Sheehan and Woojin Kwon and Rachel Harrison and Allen North}, doi = {10.3847/1538-4357/adcb9f}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {148}, shortjournal = {The Astrophys. J.}, title = {L1448 IRS3B: Dust polarization aligned with spiral features, tracing gas flows}, volume = {985}, year = {2025}, }
• (2025). Modeling of lightcurves from reconnection-powered very high-energy flares from m87*. ApJ, 985(2), 147. (www)

  @article{ , abstract = {The black hole at the center of M87 is observed to flare regularly in the very high-energy (VHE) band, with photon energies ≳100 GeV. The rapid variability, which can be as short as 2 days in the VHE lightcurve, constrains some of the flares to originate close to the black hole. Magnetic reconnection is a promising candidate for explaining the flares, where the VHE emission comes from background soft photons that inverse Compton scatter off of high-energy electron–positron pairs in the reconnecting current sheet. In this work, we ray trace photons from a current sheet near the black hole event horizon during a flux eruption in a magnetically arrested state in a general relativistic magnetohydrodynamics simulation. We incorporate beaming of the Compton up-scattered photons, based on results from radiative kinetic simulations of relativistic reconnection. We then construct VHE lightcurves that account for the dynamics of the current sheet and lensing from general-relativistic effects. We find that most of the flux originates in the inner 5 gravitational radii, and beaming is essential to explain the observed flux from the strongest VHE flares. The ray traced lightcurves show features resulting from the changing volume of the reconnecting current sheet on timescales that can be consistent with observations. Furthermore, we find that the amount of beaming depends strongly on two effects: (i) the current sheet inclination with respect to the observer and (ii) the anisotropy in the direction of motion of the accelerated particles.}, archive = {J_ApJ}, author = {Siddhant Solanki and Jordy Davelaar and Bart Ripperda and Alexander Philippov}, doi = {10.3847/1538-4357/adcba9}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {147}, shortjournal = {The Astrophys. J.}, title = {Modeling of lightcurves from reconnection-powered very high-energy flares from m87*}, volume = {985}, year = {2025}, }
• (2025). Properties of the GSN 069 accretion disk from a joint X-ray and UV spectral analysis: Stress-testing quasi-periodic eruption models. ApJ, 985(2), 146. (www)

  @article{ , abstract = {We present an analysis of Hubble Space Telescope (HST) and XMM-Newton data of the tidal disruption event (TDE) candidate and quasi-periodic eruption (QPE) source GSN 069. Using ultraviolet (UV) and optical images at HST resolution, we show that GSN 069's emission consists of a point source superimposed on a diffuse stellar component. The latter accounts for ≤5% of the UV emission in the inner 0 \mathop{.}\limits^{\unicode{x02033}} 5 × 0 \mathop{.}\limits^{\unicode{x02033}} 5 region, while the luminosity of the former cannot be attributed to stars. Analyzing the 2014/2018 HST UV spectra, we show that to leading order the intrinsic spectral shape is ν L ν ∝ ν 4/3 , with ∼10% far-UV flux variability between epochs. The contemporaneous X-ray and UV spectra can be modeled self-consistently in a thin disk framework. At observed epochs, the disk had an outer radius ( R out ) of { \mathcal O }(1{0}^{3}{R}_{{\rm{g}}}) , showing both cooling and expansion over 4 yr. Incorporating relativistic effects via numerical ray tracing, we constrain the disk inclination angle ( i ) to be 30 ∘ ≲ i ≲ 65 ∘ and identify a narrow region of spin–inclination parameter space that describes the observations. These findings confirm that GSN 069 hosts a compact, viscously expanding accretion disk likely formed after a TDE. The implications for QPE models are (i) that no published disk-instability model can explain the disk's stability in 2014 (no QPEs) and its instability in 2018 (QPEs present), and (ii) while the disk size in 2018 allows for orbiter–disk interactions to produce QPEs, in 2014 the disk was already sufficiently extended, yet no QPEs were present. These findings pose challenges to existing QPE models.}, archive = {J_ApJ}, author = {M. Guolo and A. Mummery and T. Wevers and M. Nicholl and S. Gezari and A. Ingram and D. R. Pasham}, doi = {10.3847/1538-4357/adcbac}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {146}, shortjournal = {The Astrophys. J.}, title = {Properties of the GSN 069 accretion disk from a joint X-ray and UV spectral analysis: Stress-testing quasi-periodic eruption models}, volume = {985}, year = {2025}, }
• (2025). Discovery of small-scale flows in the void of a coronal mass ejection with high-cadence images acquired by the metis coronagraph on board solar orbiter. ApJ, 985(1), 145. (www)

  @article{ , abstract = {On 2022 March 26, the ESA Solar Orbiter mission observed the early evolution of a coronal mass ejection (CME). On that day, the spacecraft was at a heliocentric distance of 0.32 au and a longitude separation from Earth of 74 \mathop{.}\limits^{\unicode{x000b0}} 5. The CME source region, observed with the Solar Orbiter Polarimetric and Helioseismic Imager magnetometer, shows no preexisting filament or flux rope. The event was first observed in the inner corona by the Solar Orbiter Extreme Ultraviolet Imager instrument with the Full Sun Imager telescope, showing the initial propagation of a flux rope seen face-on in the EUV, and formed during the eruption. Higher up, the event was observed by Metis with the Visible Light channel with an unprecedented time cadence of 20 s and a spatial resolution of 20" corresponding to about 4600 km bin −1 . The sequence of total brightness images shows the existence of small-scale circular flows inside the expanding flux rope, surrounded by multiple nested arch-shaped features. These motions, never reported so far, occur inside the void of the CME, with projected speed ∼40% higher than the CME propagation speed. The formation of the flux rope during the eruption suggests that these motions can be interpreted as a signature of conversion of magnetic writhe into twist, starting from the shearing of a preexisting arcade.}, archive = {J_ApJ}, author = {Alessandro Bemporad and Lucia Abbo and Kinga Albert and Emanuele Amato and Vincenzo Andretta and Ruggero Biondo and Aleksandr Burtovoi and Daniele Calchetti and Vania Da Deppo and Yara De Leo and Silvano Fineschi and Federica Frassati and Catia Grimani and Giovanna Jerse and Federico Landini and Salvatore Mancuso and Giampiero Naletto and Gianalfredo Nicolini and Maurizio Pancrazzi and Julian Blanco Rodríguez and Marco Romoli and Giuliana Russano and Clementina Sasso and Daniele Spadaro and Marco Stangalini and Hanna Strecker and David Orozco Suárez and Roberto Susino and Luca Teriaca and Michela Uslenghi and Gherardo Valori}, doi = {10.3847/1538-4357/adc7ff}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {145}, shortjournal = {The Astrophys. J.}, title = {Discovery of small-scale flows in the void of a coronal mass ejection with high-cadence images acquired by the metis coronagraph on board solar orbiter}, volume = {985}, year = {2025}, }
• (2025). A power spectral study of PHANGS galaxies with JWST MIRI: On the spatial scales of dust and polycyclic aromatic hydrocarbons. ApJ, 985(1), 144. (www)

  @article{ , abstract = {The interstellar medium (ISM) consists of a diversity of structures across a range of spatial scales, intimately tied to galactic evolution. In this work, Fourier analysis is used to characterize the spatial structures of dust and polycyclic aromatic hydrocarbons (PAHs) in the ISM of Physics at High Angular Resolution in Nearby GalaxieS (PHANGS) James Webb Space Telescope (JWST) galaxies, observed in the four photometric mid-infrared filters from F770W to F2100W (i.e., 7.7–21 μ m). We quantify the abundance of structure on different spatial scales using the power-law slope, α , of the spatial power spectra. The distribution of α across all length scales differs significantly between filters, with steeper slopes for PAH-dominated filters ( {\alpha }_{{\rm{F}}770{\rm{W}}}=2.1{9}_{-0.15}^{+0.16} , {\alpha }_{{\rm{F}}1130{\rm{W}}}=1.8{8}_{-0.37}^{+0.25} ) and shallower for the dust continuum ( {\alpha }_{{\rm{F}}1000{\rm{W}}}=1.4{8}_{-0.47}^{+0.33} , {\alpha }_{{\rm{F}}2100{\rm{W}}}=0.9{4}_{-0.28}^{+0.23} ). The distribution of α across galaxies is narrower for PAH-dominated than for thermal dust-dominated bands, highlighting that PAHs trace photodissociation regions dominated by similar physical processes, whereas dust structures are an integrated property over the diverse evolutionary histories of their host galaxies. Unlike dust structures, PAH-sensitive bands display a break in the power spectrum: below a characteristic scale, {\ell }_{0}=160\,{\mathrm{pc}}_{-50\,\mathrm{pc}}^{+110\,\mathrm{pc}} , PAH structures are suppressed.}, archive = {J_ApJ}, author = {Charlie Lind-Thomsen and Albert Sneppen and Charles L. Steinhardt}, doi = {10.3847/1538-4357/adc808}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {144}, shortjournal = {The Astrophys. J.}, title = {A power spectral study of PHANGS galaxies with JWST MIRI: On the spatial scales of dust and polycyclic aromatic hydrocarbons}, volume = {985}, year = {2025}, }
• (2025). Reactive molecular dynamics simulations of iron reduction on lunar and asteroidal surfaces by micrometeoroids and solar wind. ApJ, 985(1), 143. (www)

  @article{ , abstract = {Regolith grains and rock surfaces altered by space weathering on the Moon and S-type asteroids contain nanometer-sized metallic iron particles, known as nanophase iron (npFe 0 ). Several processes have been proposed to explain the reduction of Fe 2+ and the formation of npFe 0 , such as vapor deposition due to micrometeoroid impact or solar wind irradiation, and reduction by implanted hydrogen followed by micrometeoroid impact heating. In addition, recent analyses of Chang'e-5 samples suggested disproportionation reduction (3Fe 2+ → Fe 0 + 2Fe 3+ ). However, despite numerous observations and experiments, the exact chemical pathway driving npFe 0 formation remains controversial. Considering the recent analyses, to investigate the charge evolution of Fe atoms during micrometeoroid impacts and solar wind irradiation, reactive molecular dynamics simulations were conducted. The simulations found that micrometeoroid impacts reduced Fe atoms in fayalite by stripping electrons from O atoms. When the pressure induced by the impact reached approximately 10 GPa, disproportionation reduction, yielding Fe 3+ in addition to Fe 0 near the base of the microcrater, was also induced. Proton irradiation also reduced Fe atoms by breaking Fe–O bonds and forming O–H bonds. This result shows that neutral iron atoms can be produced even in environments without significant vaporization as the Chang'e-5 samples indicate. However, in the simulations, the reduced Fe atoms did not aggregate into npFe 0 particles. The simulations in this work consider the potential derived from the crystal structure of olivine. To simulate the formation of npFe 0 particles, a different potential may be needed, which requires further studies.}, archive = {J_ApJ}, author = {Daigo Shoji}, doi = {10.3847/1538-4357/adcb3f}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {143}, shortjournal = {The Astrophys. J.}, title = {Reactive molecular dynamics simulations of iron reduction on lunar and asteroidal surfaces by micrometeoroids and solar wind}, volume = {985}, year = {2025}, }
• (2025). The potential of coordinated gravitational-wave follow-up for improving kilonova detection prospects: Lessons from GW190425. ApJ, 985(1), 142. (www)

  @article{ , abstract = {The discovery of a kilonova associated with the GW170817 binary neutron star (BNS) merger had far-reaching implications for our understanding of several open questions in physics and astrophysics. Unfortunately, since then, only one robust BNS merger has been detected through gravitational waves, GW190425, and no electromagnetic (EM) counterpart was identified for it following an uncoordinated search. In order to estimate the potential difference that coordinated follow-up could make for future events, we analyze all reported EM follow-up observations of GW190425. We find that even for a large gravitational-wave localization uncertainty, such as this one, most of the 90% probability region can be covered within hours with a coordinated search, given the observational resources expended in this case by the community. However, more than 5 days after the GW190425 merger, its uncoordinated search covered only 50% of the probability, with some areas observed over 100 times, and some never observed. According to some models, the GW190425 kilonova could have been detected, despite the larger distance and higher component masses compared to GW170817. These results emphasize that coordinated follow-up of gravitational-wave events can, in principle, significantly improve both the chances of finding EM counterparts, and the time it takes to do so, compared to uncoordinated searches.}, archive = {J_ApJ}, author = {Ido Keinan and Iair Arcavi}, doi = {10.3847/1538-4357/adcba5}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {142}, shortjournal = {The Astrophys. J.}, title = {The potential of coordinated gravitational-wave follow-up for improving kilonova detection prospects: Lessons from GW190425}, volume = {985}, year = {2025}, }
• (2025). Upper bounds on the mass of fundamental fields from the primordial universe. ApJ, 985(1), 141. (www)

  @article{ , abstract = {We study the fluctuations in the vacuum zero-point energy associated with quantum fields and their statistical distributions during inflation. It is shown that the perturbations in the vacuum zero-point energy have large amplitudes that are highly non-Gaussian. The effects of vacuum zero-point fluctuations can be interpreted as the loop corrections in the primordial power spectrum and bispectrum. Requiring that the primordial curvature perturbation remains nearly Gaussian and the loop corrections are under perturbative control imposes strong upper bounds on the mass of fundamental fields during inflation. These bounds depend on the hierarchy of the masses in the theory, such as whether or not the masses are at similar orders. While the mass of the heaviest field in the hierarchy may not be constrained, it is shown that a combination of the masses of the fields cannot be much heavier than the Hubble scale during inflation, otherwise their vacuum zero-point fluctuations induce large non-Gaussianities in primordial perturbations. Considering the observational upper bound on the tensor to scalar ratio, we conclude that this combined mass scale is lighter than 10 14 GeV.}, archive = {J_ApJ}, author = {Hassan Firouzjahi}, doi = {10.3847/1538-4357/adcc16}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {141}, shortjournal = {The Astrophys. J.}, title = {Upper bounds on the mass of fundamental fields from the primordial universe}, volume = {985}, year = {2025}, }
• (2025). Relativistic time transformations between the solar system barycenter, earth, and moon. ApJ, 985(1), 140. (www)

  @article{ , abstract = {Relativistic corrections are essential for time transformations between geocentric, solar system barycentric, and lunicentric reference systems to account for differences in gravitational potential and relative motion. As the primary reference for Earth-based systems, Terrestrial Time ( TT ) provides the foundation for precise synchronization across spatial and temporal frameworks. To ensure consistency with TT , Barycentric Dynamical Time ( TDB ) must exhibit no average rate difference from TT . Although the International Astronomical Union has established resolutions for transformations between TT and TDB , extending these frameworks to define a lunar surface timescale ( TL ) is essential for advancing lunar exploration. This paper derives the ( TL − TT ) transformation, quantifying a secular drift of 56.0256 μ s day −1 and periodic terms, with the largest amplitude of ∼0.470 μ s at the mean anomalistic period. Additionally, the TT -compatible spatial scale and Lorentz contraction of Moon-centered positional coordinates are computed, achieving subnanosecond timing precision. These transformations, implemented in JPL ephemeris generation software, provide a robust framework for high-fidelity relativistic models of lunar timekeeping, enabling further refinements and supporting navigation, communication, and scientific operations in cis-lunar space.}, archive = {J_ApJ}, author = {Slava G. Turyshev and James G. Williams and Dale H. Boggs and Ryan S. Park}, doi = {10.3847/1538-4357/adcc18}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {140}, shortjournal = {The Astrophys. J.}, title = {Relativistic time transformations between the solar system barycenter, earth, and moon}, volume = {985}, year = {2025}, }
• (2025). Multimessenger emission by magnetically arrested disks and relativistic jets of black hole X-ray binaries. ApJ, 985(1), 139. (www)

  @article{ , abstract = {Black hole X-ray binaries (BHXBs) are observed in various wavelengths from radio to GeV gamma rays. Several BHXBs, including MAXI J1820+070 and Cygnus X-1, are also found to emit ultrahigh-energy (UHE; photon energy > 100 TeV) gamma rays. The origin and production mechanism of the multiwavelength emission of BHXBs are under debate. We propose a scenario where relativistic particles from magnetically arrested disks (MADs), which could form when BHXBs are in quiescent or hard states, produce UHE gamma rays, while electrons in the jets produce GeV gamma-ray emission. Specifically, magnetic turbulence in MADs heats up and accelerates electrons and protons, while magnetic reconnection in jets accelerates electrons. Sub-PeV gamma rays and neutrinos are produced when relativistic protons interact with thermal protons and the radiation emitted by thermal electrons in the disk. We discuss the perspectives of observing sub-PeV multimessenger signals from individual BHXBs. Finally, we evaluate the integrated fluxes of the quiescent and hard-state BHXB population and find that BHXBs may contribute to the Galactic diffuse emission above ∼100 TeV.}, archive = {J_ApJ}, author = {Riku Kuze and Shigeo S. Kimura and Ke Fang}, doi = {10.3847/1538-4357/adcc1b}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {139}, shortjournal = {The Astrophys. J.}, title = {Multimessenger emission by magnetically arrested disks and relativistic jets of black hole X-ray binaries}, volume = {985}, year = {2025}, }
• (2025). Data-constrained magnetohydrodynamic simulation of a filament eruption in the decaying active region 13079 on a global scale. ApJ, 985(1), 138. (www)

  @article{ , abstract = {Filaments are special plasma phenomena embedded in the solar atmosphere, characterized by unique thermodynamic properties and magnetic structures. Magnetohydrodynamic (MHD) simulations are useful to investigate the eruption mechanisms of filaments. We conduct a data-constrained zero- β MHD simulation in spherical coordinates to investigate a C3.5 class flare triggered by an eruptive filament on 2022 August 15 in the decaying weak active region 13079. We reconstruct the three-dimensional coronal magnetic field using vector magnetograms and synoptic maps from the Solar Dynamics Observatory/Helioseismic and Magnetic Imager. We transform the vector magnetic field into Stonyhurst heliographic spherical coordinates combined with a synoptic map and construct a potential field source surface model with a magnetic flux rope embedded using the regularized Biot–Savart laws. Subsequently, we conduct a spherical zero- β MHD simulation using the message-passing interface adaptive mesh refinement versatile advection code (MPI-AMRVAC) and replicate the entire dynamic process of the filament eruption consistent with observations. With the calculation of the time–distance profile, quasi-separatrix layers, and synthetic radiation from simulated current density, we find a good agreement between our simulation and observations in terms of dynamics and magnetic topology. Technically, we provide a useful method of advanced data-constrained simulation of weak active regions in spherical coordinates. Scientifically, the model allows us to quantitatively describe and diagnose the entire process of filament eruption.}, archive = {J_ApJ}, author = {Yihua Li and Yang Guo and Jinhan Guo and M. D. Ding and Chun Xia and Rony Keppens}, doi = {10.3847/1538-4357/adccb2}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {138}, shortjournal = {The Astrophys. J.}, title = {Data-constrained magnetohydrodynamic simulation of a filament eruption in the decaying active region 13079 on a global scale}, volume = {985}, year = {2025}, }
• (2025). Polarization properties of the electromagnetic response to high-frequency gravitational wave. ApJ, 985(1), 137. (www)

  @article{ , abstract = {Electromagnetic waves (EMWs) can be generated by gravitational waves (GWs) within a magnetic field via the Gertsenshtein effect. The conversion probability between GWs and EMWs can be enhanced by inhomogeneities in the electron density and magnetic field within the magnetized plasma of both the Milky Way (MW) and the intergalactic medium in the expanding Universe. Polarized GWs can induce polarized EMWs, and the polarization properties of these EMWs can be altered by Faraday rotation as they propagate through magnetized plasma. Additionally, the polarization intensity of the EMWs may be weakened due to depolarization effects. In this study, we calculate the enhanced GW–EMW conversion in inhomogeneous magnetized plasma during the propagation of GWs through the Universe and our galaxy. We analyze the polarization states of the EMWs generated by polarized GWs and discuss the depolarization effects induced by the medium's irregularities, as well as the differential Faraday rotation occurring in multilayer polarized radiation. Our work provides alternative methods for detecting GWs and exploring their polarization states, and potentially constraining the parameters of the possible GW sources, especially the primordial black hole, contributing to the advancement of very-high-frequency GW detection and research.}, archive = {J_ApJ}, author = {Jian-Kang Li and Wei Hong and Tong-Jie Zhang}, doi = {10.3847/1538-4357/adce0a}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {137}, shortjournal = {The Astrophys. J.}, title = {Polarization properties of the electromagnetic response to high-frequency gravitational wave}, volume = {985}, year = {2025}, }
• (2025). High-time-cadence spectroscopy and photometry of stellar flares on M-dwarf YZ canis minoris with seimei telescope and TESS. II. statistical properties of Blue/Red asymmetries in the hα line. ApJ, 985(1), 136. (www)

  @article{ , abstract = {M-dwarfs frequently produce flares, and their associated coronal mass ejections (CMEs) may threaten the habitability of close-in exoplanets. M-dwarf flares sometimes show prominence eruption signatures, observed as blue/red asymmetries in the H α line. In Paper I, we reported four candidates of prominence eruptions, which show large diversity in their durations and velocities. In this study, we statistically investigate how blue/red asymmetries are related to their flare and starspot properties, using the data set from 27 H α flares in Paper I and previously reported 8 H α flares on an M-dwarf, YZ Canis Minoris. We found that these asymmetry events tend to show larger H α flare energies compared to nonasymmetry events. In particular, five out of six blue asymmetry events are not associated with white-light flares, whereas all seven red asymmetry events are associated with white-light flares. Furthermore, their starspot distributions estimated from the Transiting Exoplanet Survey Satellite light curve show that all prominence eruption candidates occurred when starspots were located on the stellar disk center as well as on the stellar limb. These results suggest that flares with lower heating rates may have a higher association rate with prominence eruptions and/or the possibility that prominence eruptions are more detectable on the limb than on the disk center on M-dwarfs. These results provide significant insights into CMEs that can affect the habitable world around M-dwarfs.}, archive = {J_ApJ}, author = {Yuto Kajikiya and Kosuke Namekata and Yuta Notsu and Kai Ikuta and Hiroyuki Maehara and Bunei Sato and Daisaku Nogami}, doi = {10.3847/1538-4357/adce7d}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {136}, shortjournal = {The Astrophys. J.}, title = {High-time-cadence spectroscopy and photometry of stellar flares on M-dwarf YZ canis minoris with seimei telescope and TESS. II. statistical properties of Blue/Red asymmetries in the hα line}, volume = {985}, year = {2025}, }
• (2025). The impact of plasma angular momentum on magnetically arrested flows and relativistic jets in hot accretion flows around black holes. ApJ, 985(1), 135. (www)

  @article{ , abstract = {In certain scenarios, the accreted angular momentum of plasma onto a black hole could be low; however, how the accretion dynamics depend on the angular momentum content of the plasma is still not fully understood. We present three-dimensional, general relativistic magnetohydrodynamic simulations of low angular momentum accretion flows around rapidly spinning black holes (with spin a = +0.9). The initial condition is a Fishbone–Moncrief (FM) torus threaded by a large amount of poloidal magnetic flux, where the angular velocity is a fraction f of the standard value. For f = 0, the accretion flow becomes magnetically arrested and launches relativistic jets but only for a very short duration. After that, free-falling plasma breaks through the magnetic barrier, loading the jet with mass and destroying the jet–disk structure. Meanwhile, magnetic flux is lost via giant, asymmetrical magnetic bubbles that float away from the black hole. The accretion then exits the magnetically arrested state. For f = 0.1, the dimensionless magnetic flux threading the black hole oscillates quasiperiodically. The jet–disk structure shows concurrent revival and destruction while the gas outflow efficiency at the event horizon changes accordingly. For f ≥ 0.3, we find that the dynamical behavior of the system starts to approach that of a standard accreting FM torus. Our results thus suggest that the accreted angular momentum is an important parameter that governs the maintenance of a magnetically arrested flow and launching of relativistic jets around black holes.}, archive = {J_ApJ}, author = {Ho-Sang Chan and Prasun Dhang and Jason Dexter and Mitchell C. Begelman}, doi = {10.3847/1538-4357/adce7f}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {135}, shortjournal = {The Astrophys. J.}, title = {The impact of plasma angular momentum on magnetically arrested flows and relativistic jets in hot accretion flows around black holes}, volume = {985}, year = {2025}, }
• (2025). Collisionless shocks having relativistic velocities in relativistically hot plasmas. ApJ, 985(1), 134. (www)

  @article{ , abstract = {Shocks in relativistically hot plasmas are thought to exist in various high-energy astrophysical phenomena, but it is not clear how relativistic collisionless shocks are formed, and whether particles are accelerated by the shock as in the case of cold upstream. In this work, collisionless shocks with a relativistic shock velocity in relativistically hot, unmagnetized electron–positron plasmas are investigated by two-dimensional particle-in-cell simulations. It is shown that the upstream flow is dissipated by the Weibel instability, so that the relativistic collisionless shock is formed as in the case of cold upstream. The density and magnetic field structures around the shock front are almost independent of the upstream temperature when the spatial scale is normalized by the inertial length scale, which takes into account the relativistic temperature. This can be understood by considering the pressure anisotropy, which asymptotically approaches a finite value due to the relativistic beaming effect, even as the temperature becomes relativistically hotter and hotter. In addition, as long as the shock velocity is relativistic, some particles are accelerated, forming a power-law energy spectrum similar to that in the cold upstream.}, archive = {J_ApJ}, author = {Kazuki Kamiido and Yutaka Ohira}, doi = {10.3847/1538-4357/adced6}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {134}, shortjournal = {The Astrophys. J.}, title = {Collisionless shocks having relativistic velocities in relativistically hot plasmas}, volume = {985}, year = {2025}, }
• (2025). A comparison of geminid models with the PSP/WISPR-observed phaethon dust trail. ApJ, 985(1), 133. (www)

  @article{ , abstract = {White-light observations from the Wide-Field Imager for Parker Solar Probe (WISPR) instrument on NASA's Parker Solar Probe recently revealed the presence of a narrow, dense dust trail close to the orbit of asteroid 3200 Phaethon. Although Geminid related, it aligns imperfectly with Phaethon's orbit and known Geminid meteoroid orbits. To address the nature of this dust trail, we performed a detailed comparison between the WISPR trail observations and several well-developed Geminid models. Simulating these models in the WISPR field of view visually demonstrates that the WISPR trail almost certainly represents the true "density core" of the Geminid stream. Trends in model trail width and offset from Phaethon's orbit, both as functions of true anomaly, agree with observations to varying extents. All the models, however, place their apparent core interior to the parent orbit due to Poynting–Robertson forces, contradictory to the WISPR trail, which is exterior to Phaethon's orbit. Therefore, Phaethon's current orbit likely does not represent the orbit of the system parent, which most probably had a larger semimajor axis. These findings provide new initial conditions for future Geminid models, with WISPR identifying the Geminid core's position.}, archive = {J_ApJ}, author = {Karl Battams and Galina O. Ryabova and Angel J. Gutarra-Leon and Jamey R. Szalay and Brendan M. Gallagher and Wolf Cukier}, doi = {10.3847/1538-4357/adc801}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {133}, shortjournal = {The Astrophys. J.}, title = {A comparison of geminid models with the PSP/WISPR-observed phaethon dust trail}, volume = {985}, year = {2025}, }
• (2025). Cosmology from point clouds with dark matter halos from the quijote simulations. ApJ, 985(1), 132. (www)

  @article{ , abstract = {We train a novel deep learning architecture to perform likelihood-free inference on the value of the cosmological parameters from halo catalogs of the Quijote N -body simulations. Our model takes as input a halo catalog where each halo is characterized by its position, mass, and velocity modulus. By construction, our model is E(3) invariant and is designed to extract information hierarchically. Unlike graph neural networks, it does not require the transformation of the input halo (or galaxy) catalog into a graph. Given its simplicity, our model can process point clouds with large numbers of points. We discuss the advantages of this class of methods but also point out their limitations and potential ways to improve them for cosmological data.}, archive = {J_ApJ}, author = {Atrideb Chatterjee and Francisco Villaescusa-Navarro}, doi = {10.3847/1538-4357/adc99d}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {132}, shortjournal = {The Astrophys. J.}, title = {Cosmology from point clouds with dark matter halos from the quijote simulations}, volume = {985}, year = {2025}, }
• (2025). Exploring cosmological constraints of the weak gravitational lensing and galaxy clustering joint analysis in the CSST photometric survey. ApJ, 985(1), 131. (www)

  @article{ , abstract = {We explore the joint weak lensing and galaxy clustering analysis from the photometric survey operated by the China Space Station Telescope (CSST) and study the strength of the cosmological constraints. We employ a high-resolution JiuTian-1G simulation to construct a partial-sky light cone to z = 3 covering 100 deg 2 and obtain the CSST galaxy mock samples based on an improved semianalytical model. We perform a multi-lens-plane algorithm to generate corresponding synthetic weak lensing maps and catalogs. Then we generate the mock data based on these catalogs considering the instrumental and observational effects of the CSST and use the Markov Chain Monte Carlo method to perform the constraints. The covariance matrix includes non-Gaussian contributions and supersample covariance terms, and the systematics from intrinsic alignments, galaxy bias, photometric redshift uncertainties, shear calibration, and nonlinear effects are considered in the analysis. We find that the constraint result is comparable to that from Stage III surveys, and it can be significantly improved further in the full CSST survey with 17,500 deg 2 . This indicates the CSST photometric survey is powerful for exploring the Universe.}, archive = {J_ApJ}, author = {Qi Xiong and Yan Gong and Xingchen Zhou and Hengjie Lin and Furen Deng and Ziwei Li and Ayodeji Ibitoye and Xuelei Chen and Zuhui Fan and Qi Guo and Ming Li and Yun Liu and Wenxiang Pei}, doi = {10.3847/1538-4357/adcb44}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {131}, shortjournal = {The Astrophys. J.}, title = {Exploring cosmological constraints of the weak gravitational lensing and galaxy clustering joint analysis in the CSST photometric survey}, volume = {985}, year = {2025}, }
• (2025). SOFIA/upGREAT imaging spectroscopy of the [C ii] 158 μm fine-structure line toward the sgr a region in the galactic center. ApJ, 985(1), 130. (www)

  @article{ , abstract = {We present SOFIA/upGREAT velocity-resolved spectral imaging and analysis of the λ 158 μ m [C ii ] spectral line toward the central 80 by 43 pc region of the Central Molecular Zone of the Galaxy. The field we imaged with 14'' (0.6 pc) spatial and 1 km s −1 spectral resolution contains the circumnuclear disk (CND) around the central black hole Sgr A*, the neighboring thermal Arched Filaments, the nonthermal filaments of the Radio Arc, and the three luminous central star clusters. [C ii ] traces emission from the CND's inner edge to material orbiting at a distance of approximately 6 pc. Its velocity field reveals no sign of inflowing material nor interaction with winds from the Sgr A East supernova remnant. Wide-field imaging of the Sgr A region shows multiple circular segments, including the thermal Arched Filaments, that are centered on a region that includes the Quintuplet cluster. We examine the possibility that the Arched Filaments and other large-scale arcs trace transient excitation events from supernova blast waves. Along the Arched Filaments, comparisons among far-infrared fine-structure lines show changes in the ionization state over small scales and that high-excitation lines are systematically shifted in position from the other lines. These also point to transient fast winds that produce shocks on the surface of the Arches cloud to produce additional local ultraviolet (UV) radiation to excite the Arched Filaments on a cloud surface illuminated by UV from hot stars.}, archive = {J_ApJ}, author = {A. I. Harris and R. Güsten and M. A. Requena-Torres and D. Riquelme and M. R. Morris and G. J. Stacey and J. Stutzki and Y. Okada and E. Chambers and M. Mertens and C. Fischer}, doi = {10.3847/1538-4357/adcb48}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {130}, shortjournal = {The Astrophys. J.}, title = {SOFIA/upGREAT imaging spectroscopy of the [C ii] 158 μm fine-structure line toward the sgr a region in the galactic center}, volume = {985}, year = {2025}, }
• (2025). Trials and tribulations of chemodynamical tagging: Investigating the recovery of open clusters in the gaia data release 3 and GALAH data release 4 catalogs. ApJ, 985(1), 129. (www)

  @article{ , abstract = {Chemodynamical tagging has been suggested as a powerful tool to trace stars back to their birth clusters. However, the efficacy of chemodynamical tagging as a means to recover individual stellar clusters is still under debate. In this study, we present a detailed investigation of chemodynamical tagging of open clusters using both dynamical and chemical data from the Gaia Data Release 3 and GALAH Data Release 4 surveys, respectively. Using a sample of open clusters and mock field stars, we conduct a bootstrap analysis to evaluate every unique combination of orbital components ( E , J R , J ϕ , J Z ) and chemical abundances ([X/Fe] for O, Na, Mg, Al, Si, K, Ca, Sc, Ti, Cr, Mn, Ni, Cu, Y, and Ba) on how well they recover open clusters when used as parameters in the clustering algorithm HDBSCAN. We find that using primarily dynamical orbital parameters leads to the highest recovery rate of open cluster stars. Nevertheless, even employing the best performing parameter combinations leads to low open cluster recovery rates. We find that, in most cases, chemodynamical tagging of open clusters using blind clustering algorithms is not efficient, which is in line with previous theoretical and observational work. However, we show that the addition of cuts based on metallicity, age, and birth radius in order to reduce the size of the clustering catalog can marginally improve the recovery rate of open clusters.}, archive = {J_ApJ}, author = {Nicholas A. Barth and David Mendez and Rana Ezzeddine and Yuxi(Lucy) Lu and Leslie M. Morales and Zachary R. Claytor and Jamie Tayar}, doi = {10.3847/1538-4357/adccbc}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {129}, shortjournal = {The Astrophys. J.}, title = {Trials and tribulations of chemodynamical tagging: Investigating the recovery of open clusters in the gaia data release 3 and GALAH data release 4 catalogs}, volume = {985}, year = {2025}, }
• (2025). The low-redshift lyman continuum survey: The roles of stellar feedback and interstellar medium geometry in LyC escape. ApJ, 985(1), 128. (www)

  @article{ , abstract = {One of the fundamental questions of cosmology is the origin and mechanism(s) responsible for the reionization of the Universe beyond z ∼ 6. Many studies have focused on Hubble Space Telescope (HST) Cosmic Origins Spectrograph (COS) observations of local ( z ∼ 0.3) galaxies emitting ionizing radiation (Lyman continuum, or LyC) for insight. However, LyC measurements can depend on chance alignment of optically thin channels with the observer. In addition, low signal in the spectra of these faint LyC emitters inhibits constraints on gas geometry and stellar populations. To circumvent these limitations, we analyze stacks of a consolidated sample of HST/COS observations of the LyC in 89 galaxies at z ∼ 0.3. From fitting of the continuum, we obtain information about the underlying stellar populations, emergent LyC, and neutral interstellar medium geometry. We find that most LyC nondetections are not leaking appreciable LyC ( {f}_{\mathrm{esc}}^{\mathrm{LyC}} < 1%), but also that exceptional cases point to spatial variations in the LyC escape fraction {f}_{\mathrm{esc}}^{\mathrm{LyC}} . Stellar populations younger than 3 Myr lead to an increase in ionizing feedback, which in turn increases the isotropy of LyC escape. Wolf–Rayet stars and 3–6 Myr populations appear to play little role in LyC escape. Mechanical feedback from supernovae in 8–10 Myr stellar populations is important for anisotropic gas distributions needed for LyC escape. While mechanical feedback is necessary for any LyC escape, high {f}_{\mathrm{esc}}^{\mathrm{LyC}} (>5%) also requires a confluence of young stars and ionizing feedback. A two-stage burst of star formation is critical to producing this optimal LyC escape scenario, and should be considered fundamental to identifying LyC emitters at the Epoch of Reionization.}, archive = {J_ApJ}, author = {Sophia R. Flury and Anne E. Jaskot and Alberto Saldana-Lopez and M. S. Oey and John Chisholm and Ricardo Amorín and Omkar Bait and Sanchayeeta Borthakur and Cody Carr and Henry C. Ferguson and Mauro Giavalisco and Matthew Hayes and Timothy Heckman and Alaina Henry and Zhiyuan Ji and Lena Komarova and Florian Leclercq and Alexandra Le Reste and Stephan McCandliss and Rui Marques-Chaves and Göran Östlin and Laura Pentericci and Swara Ravindranath and Michael Rutkowski and Claudia Scarlata and Daniel Schaerer and Trinh Thuan and Maxime Trebitsch and Eros Vanzella and Anne Verhamme and Bingjie Wang and Gábor Worseck and Xinfeng Xu}, doi = {10.3847/1538-4357/adc305}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {128}, shortjournal = {The Astrophys. J.}, title = {The low-redshift lyman continuum survey: The roles of stellar feedback and interstellar medium geometry in LyC escape}, volume = {985}, year = {2025}, }
• (2025). A generalized method for characterizing 21 cm power spectrum signal loss from temporal filtering of drift-scanning visibilities. ApJ, 985(1), 127. (www)

  @article{ , abstract = {A successful detection of the cosmological 21 cm signal from intensity mapping experiments (e.g., during the Epoch of Reionization or Cosmic Dawn) is contingent on the suppression of subtle systematic effects in the data. Some of these systematic effects, with mutual coupling a major concern in interferometric data, manifest with temporal variability distinct from that of the cosmological signal. Fringe-rate filtering—a time-based Fourier filtering technique—is a powerful tool for mitigating these effects; however, fringe-rate filters also attenuate the cosmological signal. Analyses that employ fringe-rate filters must therefore be supplemented by careful accounting of the signal loss incurred by the filters. In this paper, we present a generalized formalism for characterizing how the cosmological 21 cm signal is attenuated by linear time-based filters applied to interferometric visibilities from drift-scanning telescopes. Our formalism primarily relies on analytic calculations, and therefore has a greatly reduced computational cost relative to traditional Monte Carlo signal loss analyses. We apply our signal loss formalism to a filtering strategy used by the Hydrogen Epoch of Reionization Array (HERA) and compare our analytic predictions against signal loss estimates obtained through a Monte Carlo analysis. We find excellent agreement between the analytic predictions and Monte Carlo estimates and therefore conclude that HERA, as well as any other drift-scanning interferometric experiment, should use our signal loss formalism when applying linear, time-based filters to the visibilities.}, archive = {J_ApJ}, author = {Robert Pascua and Zachary E. Martinot and Adrian Liu and James E. Aguirre and Nicholas S. Kern and Joshua S. Dillon and Michael J. Wilensky and Nicolas Fagnoni and Eloy de Lera Acedo and David R. DeBoer}, doi = {10.3847/1538-4357/adc37d}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {127}, shortjournal = {The Astrophys. J.}, title = {A generalized method for characterizing 21 cm power spectrum signal loss from temporal filtering of drift-scanning visibilities}, volume = {985}, year = {2025}, }
• (2025). Temporarily quiescent galaxies at cosmic dawn: Probing bursty star formation. ApJ, 985(1), 126. (www)

  @article{ , abstract = {The bursty, time-variable nature of star formation in the first billion years, as revealed by JWST, drives phases of temporary quiescence in low-mass galaxies that quench after starbursts. These galaxies provide unique probes of the burstiness of early star formation and its underlying physical processes. Using the serra cosmological zoom-in simulations, we analyze over 200 galaxies with M ⋆ < 10 9.5 M ⊙ at z ∼ 6–8, finding that most experience quiescent phases driven by stellar feedback, with minimal influence from environmental effects. The fraction of temporarily quiescent galaxies increases with decreasing mass and luminosity, representing the dominant population at M ⋆ < 10 8 M ⊙ and M UV > −17. By forward modeling their spectral energy distributions, we show that they are faint (〈 M UV 〉 = −15.6 for M ⋆ = 10 8 M ⊙ ), have strong Balmer breaks (>0.5), and no emission lines. Comparing our predicted fractions with JWST results, we find similar luminosity-dependent trends; however, the observed fractions of temporarily quiescent galaxies at M UV ∼ −20 to −19 are higher, suggesting that stronger feedback or additional mechanisms beyond supernovae may be at play. We propose searching for F200W dropouts and satellites in the proximity (<5'') of massive (>10 10 M ⊙ ) galaxies as effective strategies to uncover the hidden majority of faint ( M UV > −17), temporarily quiescent systems, crucial for constraining early feedback processes in low-mass galaxies.}, archive = {J_ApJ}, author = {Viola Gelli and Andrea Pallottini and Stefania Salvadori and Andrea Ferrara and Charlotte Mason and Stefano Carniani and Michele Ginolfi}, doi = {10.3847/1538-4357/adc722}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {126}, shortjournal = {The Astrophys. J.}, title = {Temporarily quiescent galaxies at cosmic dawn: Probing bursty star formation}, volume = {985}, year = {2025}, }
• (2025). UNCOVER: Significant reddening in cosmic noon quiescent galaxies. ApJ, 985(1), 125. (www)

  @article{ , abstract = {We explore the physical properties of five massive quiescent galaxies at z ∼ 2.5, revealing the presence of nonnegligible dust reservoirs. JWST NIRSpec observations were obtained for each target, finding no significant line emission; multiple star formation tracers independently place upper limits between 0.1 and 10 M ⊙ yr −1 . Spectral energy distribution modeling with Prospector infers stellar masses of {\mathrm{log}}_{10}[M/{M}_{\odot }]\sim 10-11 and stellar-mass-weighted ages between 1 and 2 Gyr. The inferred mass-weighted effective radii ( r eff ∼ 0.4–1.4 kpc) and inner 1 kpc stellar surface densities ( {\mathrm{log}}_{10}[{\Sigma }_{\lt 1\,\mathrm{kpc}}/{M}_{\odot }\,{\mathrm{kpc}}^{2}]\gtrsim 9 ) are typical of quiescent galaxies at z ≳ 2. The galaxies predominately display negative color gradients (redder core and bluer outskirts); for one galaxy, this effect results from a dusty core. Unlike local quiescent galaxies, we identify significant reddening in these typical cosmic noon passive galaxies; all but one require A V ≳ 0.4. This finding is in qualitative agreement with previous studies, but our deep 20-band NIRCam imaging is able to significantly suppress the dust–age degeneracy and confidently determine that these galaxies are reddened. We speculate about the physical effects that may drive the decline in dust content in quiescent galaxies over cosmic time.}, archive = {J_ApJ}, author = {Jared C. Siegel and David J. Setton and Jenny E. Greene and Katherine A. Suess and Katherine E. Whitaker and Rachel Bezanson and Joel Leja and Lukas J. Furtak and Sam E. Cutler and Anna de Graaff and Robert Feldmann and Gourav Khullar and Ivo Labbe and Danilo Marchesini and Tim B. Miller and Themiya Nanayakkara and Richard Pan and Sedona H. Price and Helena P. Treiber and Pieter van Dokkum and Bingjie Wang and John R. Weaver}, doi = {10.3847/1538-4357/adc7b7}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {125}, shortjournal = {The Astrophys. J.}, title = {UNCOVER: Significant reddening in cosmic noon quiescent galaxies}, volume = {985}, year = {2025}, }
• (2025). The nature of optical afterglows without gamma-ray bursts: Identification of AT2023lcr and multiwavelength modeling. ApJ, 985(1), 124. (www)

  @article{ , abstract = {In the past few years, the improved sensitivity and cadence of wide-field optical surveys have enabled the discovery of several afterglows without associated detected gamma-ray bursts (GRBs). We present the identification, observations, and multiwavelength modeling of a recent such afterglow (AT 2023lcr), and model three literature events (AT 2020blt, AT 2021any, and AT 2021lfa) in a consistent fashion. For each event, we consider the following possibilities as to why a GRB was not observed: (1) the jet was off-axis; (2) the jet had a low initial Lorentz factor; and (3) the afterglow was the result of an on-axis classical GRB (on-axis jet with physical parameters typical of the GRB population), but the emission was undetected by gamma-ray satellites. We estimate all physical parameters using afterglowpy and Markov Chain Monte Carlo methods from emcee . We find that AT 2023lcr, AT 2020blt, and AT 2021any are consistent with on-axis classical GRBs, and AT 2021lfa is consistent with both on-axis low Lorentz factor (Γ 0 ≈ 5–13) and off-axis ( θ obs = 2 θ jet ) high Lorentz factor (Γ 0 ≈ 100) jets.}, archive = {J_ApJ}, author = {Maggie L. Li and Anna Y. Q. Ho and Geoffrey Ryan and Daniel A. Perley and Gavin P. Lamb and Nayana A.J. and Igor Andreoni and G. C. Anupama and Eric C. Bellm and Edo Berger and Joshua S. Bloom and Eric Burns and Ilaria Caiazzo and Poonam Chandra and Michael W. Coughlin and Kareem El-Badry and Matthew J. Graham and Mansi Kasliwal and Garrett K. Keating and S. R. Kulkarni and Harsh Kumar and Frank J. Masci and Richard A. Perley and Josiah Purdum and Ramprasad Rao and Antonio C. Rodriguez and Ben Rusholme and Nikhil Sarin and Jesper Sollerman and Gokul P. Srinivasaragavan and Vishwajeet Swain and Zachary Vanderbosch}, doi = {10.3847/1538-4357/adc800}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {124}, shortjournal = {The Astrophys. J.}, title = {The nature of optical afterglows without gamma-ray bursts: Identification of AT2023lcr and multiwavelength modeling}, volume = {985}, year = {2025}, }
• (2025). Exploring effects of modified machine learning pipelines of astrochemical inventories. ApJ, 985(1), 123. (www)

  @article{ , abstract = {Machine learning pipelines for astrochemical inventories have been introduced as a useful addition to the astrochemist toolbox, having first been used to model and predict column densities in the Taurus Molecular Cloud (TMC-1). Rapid changes in the field of machine learning have provided new tools in optimizing this pipeline, including improved vector representations. Furthermore, the addition of new detections since the original model allows for a retrospective analysis of model performance, in addition to new data for the model. This study revisits TMC-1, investigating both effects of an increased detection inventory on the model and changes to various portions of the pipeline, yielding a significant improvement in column density predictions. Through these comparisons, we attempt to derive insight into the ultimate effectiveness of these models, as well as their current limitations and words of caution in their use and interpretation. Finally, we provide suggestions for future machine learning of interstellar sources.}, archive = {J_ApJ}, author = {Hannah Toru Shay and Haley N. Scolati and Gabi Wenzel and Kin Long Kelvin Lee and Aravindh N. Marimuthu and Brett A. McGuire}, doi = {10.3847/1538-4357/adc80b}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {123}, shortjournal = {The Astrophys. J.}, title = {Exploring effects of modified machine learning pipelines of astrochemical inventories}, volume = {985}, year = {2025}, }
• (2025). North+Lone star supernova host survey. i. local host-galaxy hα surface brightness and the hubble residuals of type ia supernovae. ApJ, 985(1), 122. (www)

  @article{ , abstract = {We present optical integral field unit spectroscopy acquired with the George and Cynthia Mitchell Spectrograph on the Harlan J. Smith telescope at McDonald Observatory of 94 galaxies (0.01 < z < 0.058) that have hosted Type Ia supernovae (SNe Ia). We selected host galaxies with star-forming morphology, consistent with the criteria used by A. G. Riess et al. We measured the H α surface brightness (SB) of each host galaxy within 1 kpc of the location of the supernova. Using distances from the Pantheon+ sample, we find a step in Hubble residuals (HRs) compared to local H α SB of −0.097 ± 0.051 mag at 1.9 σ significance in a sample of 73 host galaxies, where SNe in environments with smaller H α SB are, on average, less luminous after correction for light-curve shape and color. Almost all of the SNe in our sample were discovered by targeted surveys. Using an independent sample primarily from the untargeted Nearby Supernova Factory survey, M. Rigault et al. found a step of 0.045 ± 0.029 mag where SNe in passive environments are instead brighter, which is in 2.4 σ tension with our measurement. M. Rigault et al. designated SNe Ia with comparatively small HRs (<−0.1) and faint local H α SB (<log 10 (H α SB/(erg −1 s −1 kpc 2 )) = 38.32) as the M 2 population. SNe that would be classified as M 2 are less highly represented in our sample (7% versus 21%). When we include an additional 12 early-type galaxies, the number of M 2 SNe is almost doubled, although the tension with the HR step measured by M. Rigault et al. persists at 1.7 σ .}, archive = {J_ApJ}, author = {Ann M. Isaacs and Patrick L. Kelly and J. Craig Wheeler}, doi = {10.3847/1538-4357/adc916}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {122}, shortjournal = {The Astrophys. J.}, title = {North+Lone star supernova host survey. i. local host-galaxy hα surface brightness and the hubble residuals of type ia supernovae}, volume = {985}, year = {2025}, }
• (2025). The M31–M33 interaction: Impact on m31’s center-of-mass motion and satellite orbits. ApJ, 985(1), 121. (www)

  @article{ , abstract = {Inspired by recent studies of the interaction between the Milky Way and the Large Magellanic Cloud and its implications for the Milky Way's global dynamical history, we investigate how the massive satellite galaxy M33 influences the position and velocity of Andromeda's (M31) center of mass (COM) as M33 passes through M31's halo. Using recent six-dimensional phase space measurements for both galaxies, we use backward integration to revisit M33's orbital history in a massive M31 potential (3 × 10 12 M ⊙ ) for the first time. As previously concluded, we find that a first infall orbit is still the most statistically significant (≳90%) orbital solution for M33, except for a high-mass M31 combined with M31 proper motions from the Hubble Space Telescope (as opposed to Gaia), where there is a greater likelihood (∼65%) of a previous encounter. However, the minimum distance between M33 and M31 during this passage is typically ≥100 kpc, two to three times larger than the distance required to explain M33's warped stellar and gaseous disks. We quantify the magnitude and direction of M31's evolving COM position ( R COM ) and velocity ( V COM ) owing to M33, finding R COM ≈ 100–150 kpc at maximum and V COM ≈ 20–40 km s −1 . Furthermore, we explore the implications of this phenomenon for the M31 satellite system, specifically whether M33's gravitational influence is linked to the lopsided distribution of M31 satellites and whether M33 significantly perturbs the orbits of other M31 satellites. While M33 alone may not explain the lopsided nature of M31's satellite system, its dynamical impact is nonnegligible and must be accounted for in future dynamical studies of the M31 system.}, archive = {J_ApJ}, author = {Ekta Patel and Nicolás Garavito-Camargo and Ivanna Escala}, doi = {10.3847/1538-4357/adc992}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {121}, shortjournal = {The Astrophys. J.}, title = {The M31–M33 interaction: Impact on m31’s center-of-mass motion and satellite orbits}, volume = {985}, year = {2025}, }
• (2025). Bullet shooting Cloud–Cloud collision in MIR bubble n65. ApJ, 985(1), 120. (www)

  @article{ , abstract = {We report that the formation of the twin-bubble system N65 and N65bis may be caused by the cloud–cloud collision (CCC) from the Bullet Nebula. The blueshifted 13 CO gas component (N65a [47, 55] km s −1 ) is associated with the twin-bubble system, while the redshifted 13 CO gas component (N65b [55, 62] km s −1 ) is linked to the Bullet Nebula. The distinct signatures of CCC, such as the bridge feature, the U-shaped cavity, and the complementary distribution with displacement, are found between N65a and N65b. The collision timescale is estimated to be 1.15–2.0 Myr, which is consistent with the dynamical ages of the two H ii regions in N65a (0.73 Myr for N65bis and 1.19 Myr for N65, respectively), indicating their CCC-related origin. A total of 354 young stellar objects (YSOs) are found, which are clustered into eight minimum spanning tree groups. The distribution of M1 (at the post-frontal edge) and M2, M3, M4 (at the pre-frontal edge) suggests that the CCC triggers star formation along the collision path of b=0\mathop{.}\limits^{^\circ }35 , with younger YSOs present at the pre-frontal edge. Therefore, the bipolar morphology of the twin-bubble system can be interpreted by the collision of N65a and N65b along b=0\mathop{.}\limits^{^\circ }35 about 2 Myr ago.}, archive = {J_ApJ}, author = {En Chen and Xi Chen and Min Fang and Xuepeng Chen and Qianru He and Tian Yang}, doi = {10.3847/1538-4357/adc9a3}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {120}, shortjournal = {The Astrophys. J.}, title = {Bullet shooting Cloud–Cloud collision in MIR bubble n65}, volume = {985}, year = {2025}, }
• (2025). Analysis of multi-epoch JWST images of ∼300 little red dots: Tentative detection of variability in a minority of sources. ApJ, 985(1), 119. (www)

  @article{ , abstract = {The James Webb Space Telescope (JWST) has revealed a population of red and compact sources at z ≳ 5 known as "little red dots" (LRDs) that are likely active galactic nuclei (AGNs). Here, we present a comprehensive study of the variability of 314 LRDs with multi-epoch JWST observations in five deep fields: Ultra Deep Survey, GOODS-S, GOODS-N, A2744, and COSMOS. Our analyses use all publicly available JWST NIRCam imaging data in these fields, together with multi-epoch JWST MIRI images available. We measure the significance (signal-to-noise ratio or SNR var ) of the variabilities for all LRDs and statistically evaluate their variabilities using the SNR var distributions. We pay particular attention to the systematic offsets of photometric zero-points among different epochs that seem to commonly exist. The derived SNR var distributions of the LRDs, including those with broad H α /H β emission lines, follow the standard Gaussian distribution, and are generally consistent with those of the comparison samples of objects detected in the same images. This finding suggests that the LRD population, on average, does not show strong variability, which can be explained by super-Eddington accretion of the black holes in AGNs. Alternatively, many of them may be dominated by galaxies. We also find eight strongly variable LRD candidates with variability amplitudes of 0.24–0.82 mag. The rest-frame optical spectral energy distributions of these variable LRDs should have a significant AGN contribution. Future JWST observations will provide more variability information on LRDs.}, archive = {J_ApJ}, author = {Zijian Zhang and Linhua Jiang and Weiyang Liu and Luis C. Ho}, doi = {10.3847/1538-4357/adcb3e}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {119}, shortjournal = {The Astrophys. J.}, title = {Analysis of multi-epoch JWST images of ∼300 little red dots: Tentative detection of variability in a minority of sources}, volume = {985}, year = {2025}, }
• (2025). Modeling particle acceleration and release from solar eruptions. ApJ, 985(1), 118. (www)

  @article{ , abstract = {Determining the relative contribution of solar flares versus coronal mass ejections in large solar energetic particle (SEP) events is a long-standing problem. Flare-accelerated particles may travel through complex magnetic fields in the eruption region and escape into interplanetary space, thereby contributing to large SEP events. The process by which flare accelerated particles are released into the heliosphere is poorly understood and yet is critical to advancing our understanding of SEPs. In this work, we address the release problem by solving the focused transport equation in the context of a 2.5D ARMS magnetohydrodynamic simulation of a breakout coronal mass ejection (CME)/flare event. We find that particles accelerated by flare reconnection can be released into interplanetary space through interchange reconnection between closed and open field lines. These particles can contribute directly to SEP events and may become an important seed population for further acceleration by CME-driven shocks. Additionally, we find that the energetic particle fluxes in the inner heliosphere remain elevated for an extended period, allowing them to contribute to SEP acceleration by subsequent CMEs. This study represents the first direct particle modeling of how flare-accelerated particles can contribute to major SEP events.}, archive = {J_ApJ}, author = {Xiaocan Li and Joel Dahlin and Fan Guo and Bin Zhuang and Sophie Masson and Spiro Antiochos}, doi = {10.3847/1538-4357/adcb42}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {118}, shortjournal = {The Astrophys. J.}, title = {Modeling particle acceleration and release from solar eruptions}, volume = {985}, year = {2025}, }
• (2025). Multimodality in the search for new physics in pulsar timing data and the case of kination-amplified gravitational-wave background from inflation. ApJ, 985(1), 117. (www)

  @article{ , abstract = {We investigate the kination-amplified inflationary gravitational-wave background (GWB) interpretation of the signal recently reported by various pulsar timing array (PTA) experiments. Kination is a post-inflationary phase in the expansion history dominated by the kinetic energy of some scalar field, characterized by a stiff equation of state w = 1. Within the inflationary GWB model, we identify two modes that can fit the current data sets (NANOGrav and EPTA) with equal likelihood: the kination-amplification (KA) mode and the ordinary, no-kination-amplification (no-KA) mode. The multimodality of the likelihood motivates a Bayesian analysis with nested sampling. We analyze the free spectra of current PTA data and mock free spectra constructed with higher signal-to-noise ratios using nested sampling. The analysis of the mock spectrum designed to be consistent with the best fit to the NANOGrav 15 yr (NG15) data successfully reveals the expected bimodal posterior for the first time while excluding the reheating mode that appears in the fit to the current NG15 data, making a case for our correct and comprehensive treatment of potential multimodal posteriors arising from future PTA data sets. The resultant Bayes factor is { \mathcal B }\equiv {{ \mathcal Z }}_{{\rm{no}}-{\rm{KA}}}/{{ \mathcal Z }}_{{\rm{KA}}}=2.9\pm 1.9 , indicating comparable statistical significance between the two modes. Given the theoretical model-building challenges of producing highly blue-tilted primordial tensor spectra, the KA mode has the advantage of requiring less blue primordial spectra, compared with the no-KA mode. The synergy between future cosmic microwave background polarization, pulsar timing, and laser interferometer measurements of gravitational waves will help resolve the ambiguity implied by the multimodal posterior in PTA-only searches.}, archive = {J_ApJ}, author = {Bohua Li and Joel Meyers and Paul R. Shapiro}, doi = {10.3847/1538-4357/adcc14}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {117}, shortjournal = {The Astrophys. J.}, title = {Multimodality in the search for new physics in pulsar timing data and the case of kination-amplified gravitational-wave background from inflation}, volume = {985}, year = {2025}, }
• (2025). Saturn’s recurrent auroral flashes in the equinoctial campaign. ApJ, 985(1), 116. (www)

  @article{ , abstract = {The past decades of Cassini's investigation around Saturn have revealed the frequent occurrence of ∼1 hr quasiperiodic (QP) signatures in the in situ magnetic field and plasma measurements and plasma wave observations. Saturn's aurora, as the response to the planet's magnetospheric dynamics, is also observed to exhibit transient features that can reoccur with a strikingly similar periodicity. Previous investigations have associated these features with energetic plasma injections, standing Alfvén waves, and dayside magnetodisk reconnections, which all require a closed-field configuration. However, both previous and our analyses of the Hubble Space Telescope (HST) images, as Saturn approached the equinox (when both poles are in the field of view), reveal that transient auroral emissions are strictly nonconjugate between hemispheres—they occur in either the north or south alone. This picture is matchable with the open-configured, north–south asymmetric magnetopause reconnection. We also present a detailed case analysis of Cassini's measurements for a prolonged period before and after a sequence of transient auroral brightenings observed in HST's visits G1–G4. We show that the northern lobe featured hourly QP pulsations in the magnetic field, electron flux, and whistler-mode hiss. In an interval outside HST exposures, we observed tens to hundreds of keV electrons in the antiparallel direction associated with upward field-aligned currents, which can in turn produce aurora. This is potentially suggestive of reconnection processes at the magnetopause, but are limited in the spatial scale.}, archive = {J_ApJ}, author = {Tianshu Qin and Sarah V. Badman and Zhonghua Yao and Yan Xu and Elias Roussos}, doi = {10.3847/1538-4357/adce06}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {116}, shortjournal = {The Astrophys. J.}, title = {Saturn’s recurrent auroral flashes in the equinoctial campaign}, volume = {985}, year = {2025}, }
• (2025). Systematic bias in ionizing radiation escape fraction measurements from foreground large-scale structures. ApJ, 985(1), 115. (www)

  @article{ , abstract = {We investigate the relationship between the Ly α forest transmission in the intergalactic medium (IGM) and the environmental density of galaxies, focusing on its implications for the measurement of ionizing radiation escape fractions. Using a sample of 268 spectroscopically confirmed background galaxies at 2.7 < z < 3.0 and a galaxy density map at z ≈ 2.5 within the COSMOS field, we measure the Ly α transmission photometrically, leveraging the multiwavelength data available from the COSMOS2020 catalog. Our results reveal a weak but statistically significant positive correlation between Ly α optical depth and galaxy density contrast, suggesting that overdense regions are enriched in neutral gas, which could bias escape fraction measurements. This emphasizes the need to account for the large-scale structure of the IGM in analyses of ionizing radiation escape fractions and highlights the advantages of a photometric approach for increasing the number of sampled lines of sight across large fields. The photometric redshifts provided by upcoming all-sky surveys, such as Euclid, will make it possible to account for this bias, which can also be minimized by using fields separated in the sky by many degrees.}, archive = {J_ApJ}, author = {Claudia M. Scarlata and Wanjia Hu and Matthew J. Hayes and S. Taamoli and Ali A. Khostovan and C. M. Casey and Andreas L. Faisst and Jeyhan S. Kartaltepe and Yu-Heng Lin and Mara Salvato and Marc Rafelski}, doi = {10.3847/1538-4357/adcf9a}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {115}, shortjournal = {The Astrophys. J.}, title = {Systematic bias in ionizing radiation escape fraction measurements from foreground large-scale structures}, volume = {985}, year = {2025}, }
• (2025). Quasithermal noise in magnetized plasma: Theory and simulations. ApJ, 985(1), 114. (www)

  @article{ , abstract = {Quasithermal noise (QTN) spectroscopy has been extensively used as an accurate tool to measure electron density and temperature in unmagnetized space plasmas. The observed spectrum depends on both antenna geometry and plasma kinetic properties. When considering the QTN signal of a magnetized plasma, the description becomes more complicated. We utilize particle-in-cell (PIC) simulations to study the QTN characteristics in magnetized plasmas based on Maxwellian and two-Maxwellian distributions. We compare these results with numerical computations, finding good agreement between the two. However, there are some minor differences. Specifically, when the angle between the wavevector ( k ) and the background magnetic field was 60°, clear harmonics appeared in the QTN signal from the numerical computations, whereas in the PIC simulations, these harmonics appeared at an angle of 80°. This discrepancy may be related to additional noise in the PIC simulation and our parameter limitations. In addition, Bernstein harmonics become more pronounced as the angle increases between k and the background magnetic field. These results demonstrate that PIC simulations can be used to more accurately characterize QTN signals in complex, magnetized systems.}, archive = {J_ApJ}, author = {Xianming Zheng and Mihailo M. Martinović and Kristopher G. Klein and Viviane Pierrard and Mingzhe Liu and Xianghui Xue and Shi Tao and Kun Cheng and Han Wu and Bingkun Yu}, doi = {10.3847/1538-4357/add00f}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {114}, shortjournal = {The Astrophys. J.}, title = {Quasithermal noise in magnetized plasma: Theory and simulations}, volume = {985}, year = {2025}, }
• (2025). Analysis on the turbulent properties of current sheets in the solar wind. ApJ, 985(1), 113. (www)

  @article{ , abstract = {The energy dissipation of solar wind turbulence, closely linked to solar wind heating, is a fundamental process in space physics. Previous research indicates that current sheets in the solar wind significantly influence both energy dissipation and particle heating. However, varying definitions of current sheets can lead to inconsistent results, and treating current sheets and the ambient solar wind as uniform entities may obscure the unique turbulent properties within these structures. By analyzing 117 typical current sheets near 1 au in the solar wind over the period from 2005 to 2017, we systematically investigate the turbulent properties of these current sheets. For the first time, we present a direct relationship between the magnetic field decrease rate, thermal energy increase, intermittency, and the magnetic power spectrum inside these structures. We observe a notable increase in proton temperature accompanied by a significant decrease in the magnetic field within the current sheets. Current sheets with larger magnetic field shear angles and more pronounced magnetic field drops tend to exhibit greater inhomogeneity at the sub-ion scale. Most importantly, our analysis reveals that the steeper magnetic field spectrum in the sub-ion range is directly associated with small-scale intermittent structures, a phenomenon observable only within current sheets and gradually diminishing over longer time scales. These results imply that the fine structures within the current sheets might affect the turbulent energy dissipation, and it is necessary to distinguish the current sheet itself from the ambient solar wind when studying turbulent properties and the associated energy dissipation processes.}, archive = {J_ApJ}, author = {L. D. Wang and Y. Wang and F. S. Wei and X. S. Feng and B. Y. Wang and P. B. Zuo and W. Y. Zhang and X. J. Xu and Z. L. Zhou and X. J. Song}, doi = {10.3847/1538-4357/add142}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {113}, shortjournal = {The Astrophys. J.}, title = {Analysis on the turbulent properties of current sheets in the solar wind}, volume = {985}, year = {2025}, }
• (2025). Synchrotron circular polarization in gamma-ray burst prompt optical emission: Relativistic thermal electron contribution. ApJ, 985(1), 112. (www)

  @article{ , abstract = {Synchrotron circular polarization of a nonthermal power-law electron distribution in gamma-ray bursts (GRBs) has been studied. However, some numerical simulations have shown that the resulting distribution of electrons is a combination of a thermal component and a nonthermal power-law component. In this paper, we investigate synchrotron circular polarization using such a hybrid energy distribution of relativistic thermal and nonthermal electrons within a globally toroidal magnetic field in GRB prompt optical emission. Our results show that compared to the solely nonthermal electron model, the synchrotron circular polarization degree (PD) in the hybrid electron model can vary widely in the optical band, depending on different parameters. The lower the electron temperature, the higher the circular PD. The time-averaged circular PD in the hybrid electron model can be higher than ∼1% when the electron temperature is as low as ∼10 10 K, while in the solely nonthermal electron model it is usually lower than ∼1%. We further calculate the radiative transfer of the circular and linear polarization in the optical band. Our results show that both of the circular and linear PDs decrease with the increase of optical depth, but the linear PDs decline faster than the circular PDs. To further examine the physical mechanisms of both radiation and particle acceleration, we expect that instruments will be capable of measuring the circular polarization of GRB prompt optical emission in the future.}, archive = {J_ApJ}, author = {Kangfa Cheng and Jirong Mao and Xiaohong Zhao and Hongbang Liu and Zhegeng Chen and Gaojin Yu and Zhifu Chen}, doi = {10.3847/1538-4357/add1d7}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {112}, shortjournal = {The Astrophys. J.}, title = {Synchrotron circular polarization in gamma-ray burst prompt optical emission: Relativistic thermal electron contribution}, volume = {985}, year = {2025}, }
• (2025). SPYGLASS. VI. feedback-driven star formation in the circinus complex. ApJ, 985(1), 111. (www)

  @article{ , abstract = {Young associations provide a record that traces the star formation process, and the youngest populations connect progenitor gas dynamics to the resulting stellar populations. We therefore conduct the first comprehensive overview of the Circinus Complex, an understudied and massive (∼1500 M ⊙ ) region consisting of approximately 3100 recently formed stars alongside the Circinus Molecular Cloud. We find a clear age pattern in the contiguous central region (CirCe), where younger stars are found farther from the massive central cluster, and where the velocities are consistent with uniform expansion. By comparing this structure to an analogous STARFORGE simulation, we find that the age structure and dynamics of the association are consistent with star formation in two stages: the global collapse of the parent cloud that builds the 500 M ⊙ central cluster ASCC 79, followed by triggered star formation in a shell swept up after the first massive stars form. We also find that filaments with a range of distances from the central cluster can naturally produce multigenerational age sequences due to differences in feedback strength and exposure. Outlying populations show velocities consistent with formation independent from the CirCe region, but with similar enough velocities that they may be difficult to distinguish from one another later in their expansion. We therefore provide a new alternative view of sequential star formation that relies on feedback from a single central cluster rather than the multiple sequential generations that are traditionally invoked, while also providing insight into the star formation history of older populations.}, archive = {J_ApJ}, author = {Ronan Kerr and Juan P. Farias and Lisa Prato and Travis A. Rector and Joshua S. Speagle and Adam L. Kraus}, doi = {10.3847/1538-4357/adc0a7}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {111}, shortjournal = {The Astrophys. J.}, title = {SPYGLASS. VI. feedback-driven star formation in the circinus complex}, volume = {985}, year = {2025}, }
• (2025). Modeling triatomic biosignatures: Ozone and isotopomers. ApJ, 985(1), 110. (www)

  @article{ , abstract = {In this work, we present a new approach to produce spectroscopic constants and model first-principles synthetic spectra for all molecules of astrophysical interest. We have generalized our previous diatomic molecule simulation framework, employing transition-optimized shifted Hermite (TOSH) theory, thereby enabling the modeling of polyatomic rotational constants for molecules with three or more atoms. These capabilities are now provided by our new code Epimetheus. As a first validation of our approach, we confront our predictions and assess their accuracy against the well-studied triatomic molecule ozone 666 ( 16 O 3 ), in addition to eight of its potential isotopomers: ozone 668 ( 16 O 16 O 18 O), 686 ( 16 O 18 O 16 O), 667 ( 16 O 16 O 17 O), 676 ( 16 O 17 O 16 O), 688 ( 16 O 18 O 18 O), 868 ( 18 O 16 O 18 O), 888 ( 18 O 3 ), and 777 ( 17 O 3 ). We then assess the accuracy of these rotational constants using the Epimetheus data in our code Pandora, and generate synthetic molecular spectra. The ozone spectra presented here are purely infrared and not Raman. Epimetheus builds upon the work from our previous code Prometheus, which used the TOSH theory to account for anharmonicity for the fundamental ν = 0 → ν = 1 band, going further to now account for triatomic molecules. This is combined with thermal profile modeling for the rotational transitions. We have found that this extended method performs well, typically approximating the spectroscopic constants with errors of less than 2%. Some issues do arise depending on the symmetry group of the ozone isotopomer. From these spectroscopic constants and using our own spectral modeling code, we show that we can provide the data to produce appreciable molecular spectra, which are good approximations until high-resolution studies can be done.}, archive = {J_ApJ}, author = {Thomas M. Cross and David M. Benoit and Marco Pignatari}, doi = {10.3847/1538-4357/adbc61}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {110}, shortjournal = {The Astrophys. J.}, title = {Modeling triatomic biosignatures: Ozone and isotopomers}, volume = {985}, year = {2025}, }
• (2025). The UV legacy library of young stars as essential standards (ULLYSES) large director’s discretionary program with hubble. i. goals, design, and initial results. ApJ, 985(1), 109. (www)

  @article{ , abstract = {Specifically selected to leverage the unique ultraviolet capabilities of the Hubble Space Telescope, the Hubble Ultraviolet Legacy Library of Young Stars as Essential Standards (ULLYSES) is a Director's Discretionary program of approximately 1000 orbits—the largest ever executed—that produced a UV spectroscopic library of O and B stars in nearby low-metallicity galaxies and accreting low-mass stars in the Milky Way. Observations from ULLYSES combined with archival spectra uniformly sample the fundamental astrophysical parameter space for each mass regime, including spectral type, luminosity class, and metallicity for massive stars, and the mass, age, and disk accretion rate for low-mass stars. The ULLYSES spectral library of massive stars will be critical to characterize how massive stars evolve at different metallicities; to advance our understanding of the production of ionizing photons, and thus of galaxy evolution and the re-ionization of the Universe; and to provide the templates necessary for the synthesis of integrated stellar populations. The massive-star spectra are also transforming our understanding of the interstellar and circumgalactic media of low-metallicity galaxies. On the low-mass end, UV spectra of T Tauri stars contain a plethora of diagnostics of accretion, winds, and the warm disk surface. These diagnostics are crucial for evaluating disk evolution and provide important input to assess atmospheric escape of planets and to interpret powerful probes of disk chemistry, as observed with the Atacama Large Millimeter Array and the James Webb Space Telescope. In this paper, we motivate the design of the program, describe the observing strategy and target selection, and present initial results.}, archive = {J_ApJ}, author = {Julia Roman-Duval and William J. Fischer and Alexander W. Fullerton and Jo Taylor and Rachel Plesha and Charles Proffitt and TalaWanda Monroe and Travis C. Fischer and Alessandra Aloisi and Jean-Claude Bouret and Christopher Britt and Nuria Calvet and Joleen K. Carlberg and Paul A. Crowther and Gisella De Rosa and William V. Dixon and Catherine C. Espaillat and Christopher J. Evans and Andrew J. Fox and Kevin France and Miriam Garcia and Scott W. Fleming and Elaine M. Frazer and Ana I. Gómez de Castro and Gregory J. Herczeg and Svea Hernandez and Alec S. Hirschauer and Bethan L. James and Christopher M. Johns-Krull and Claus Leitherer and Sean Lockwood and Joan Najita and M. S. Oey and Cristina Oliveira and Tyler Pauly and I. Neill Reid and Adric Riedel and David R. Rodriguez and David Sahnow and Ravi Sankrit and Kenneth R. Sembach and Richard Shaw and Linda J. Smith and S. Tony Sohn and Debopam Som and Leonardo Úbeda and Daniel E. Welty}, doi = {10.3847/1538-4357/adc45b}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {109}, shortjournal = {The Astrophys. J.}, title = {The UV legacy library of young stars as essential standards (ULLYSES) large director’s discretionary program with hubble. i. goals, design, and initial results}, volume = {985}, year = {2025}, }
• (2025). Limits of solar flare forecasting models and new deep learning approach*. ApJ, 985(1), 108. (www)

  @article{ , abstract = {Reliable forecasting models are necessary to mitigate the risks posed by solar flares to human technology. This study introduces a novel deep learning forecasting approach while emphasizing the need for performance evaluation methods tailored to better highlight current models' limitations. In particular, we show that models reaching state-of-the-art performance with traditional metrics have similar explanatory power to no-skill persistence models and notably struggle to forecast change in activity significantly better than random guesses. We also discuss shortcomings in traditional evaluation metrics like the True Skill Statistic (TSS), which we show to be mathematically dependent on the class balance for specific models. We introduce patch-distributed CNNs, which allow us to perform full-disk forecasts while providing event probabilities in solar subregions and position predictions. This new framework offers similar information to active region (AR)-based forecasting models while bypassing the problem of unrecorded and misattributed flares that are detrimental to machine learning training. As a result, the model also operates independently of prior feature extraction and AR detection, thus offering promising operational utility with minimal external dependencies. Finally, a method is proposed for constructing balanced and independent cross-validation folds for full-disk models. Models combining Solar Dynamic Observatory (SDO)/Atmospheric Imaging Assembly EUV images as inputs show improved performance compared to employing SDO/HMI photospheric magnetograms, with a TSS of 0.74 for the C+ model and 0.62 for the M+ model.}, archive = {J_ApJ}, author = {G. Francisco and M. Berretti and S. Chierichini and R. Mugatwala and J. Fernandes and T. Barata and D. Del Moro}, doi = {10.3847/1538-4357/adc56d}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {108}, shortjournal = {The Astrophys. J.}, title = {Limits of solar flare forecasting models and new deep learning approach*}, volume = {985}, year = {2025}, }
• (2025). Possibility of using 3.3 μm polycyclic aromatic hydrocarbon luminosity as a molecular gas mass estimator. ApJ, 985(1), 107. (www)

  @article{ , abstract = {We present CO(1–0) observations of 50 star-forming galaxies at 0.01 < z < 0.35, for which 3.3 μ m polycyclic aromatic hydrocarbon (PAH) emission flux or its upper limit is available. A scaling relation between 3.3 μ m PAH luminosity and CO(1–0) luminosity is established covering ∼2 orders of magnitude in total IR luminosity and CO luminosity, with a scatter of ∼0.23 dex: {\mathrm{log}}\,{L}_{3.3}/{L}_{\odot } = (1.00\pm 0.07)\times {\rm{log}}\,{L}_{{\rm{CO}}(1-0)}^{{\prime} }/({\rm{K}}\,{\rm{km}}\,{{\rm{s}}}^{-1}\,{{\rm{pc}}}^{2}) +(−1.10 ± 0.70). The slope is near unity, allowing the use of a single value of \langle {\rm{log}}\,({L}_{3.3}/{L}_{{\rm{CO}}(1-0)}^{{\prime} })\rangle =−1.09 ± 0.36 [ L ⊙ /(K km s −1 pc 2 )] in the conversion between 3.3 μ m PAH and CO luminosities. The variation in the {L}_{3.3}/{L}_{{\rm{CO}}}^{{\prime} } ratio is not dependent on the galaxy properties, including total IR luminosity, stellar mass, and star formation rate excess. The total gas mass, estimated using the dust-to-gas ratio and dust mass, is correlated with 3.3 μ m PAH luminosity, in line with the prescription using α CO = 0.8–4.5 covering both normal star-forming galaxies and starburst galaxies. Active galactic nucleus (AGN)-dominated galaxies tend to have a lower {L}_{3.3}/{L}_{{\rm{CO}}}^{{\prime} } than non-AGN galaxies, which needs to be investigated further with an increased sample size. The established L 3.3 – {L}_{{\rm{CO}}}^{{\prime} } correlation is expected to be applicable to wide-field near-infrared spectrophotometric surveys that allow the detection of 3.3 μ m emission from numerous low-redshift galaxies.}, archive = {J_ApJ}, author = {Hyunjin Shim and Junhyun Baek and Dohyeong Kim and Minjin Kim and Hyunmi Song and Gu Lim and Jaejun Cho and Hayeong Jeong and Yejin Jeong and Ye-eun Kang and Dongseob Lee and Junyeong Park and Eunsuk Seo and Junho Song and Been Yeo}, doi = {10.3847/1538-4357/adc57f}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {107}, shortjournal = {The Astrophys. J.}, title = {Possibility of using 3.3 μm polycyclic aromatic hydrocarbon luminosity as a molecular gas mass estimator}, volume = {985}, year = {2025}, }
• (2025). Impact of magnetohydrodynamic disk wind on early evolutionary stage of protoplanetary disk and dust growth. ApJ, 985(1), 106. (www)

  @article{ , abstract = {We perform one-dimensional protoplanetary disk evolution calculations to investigate the impact of the magnetohydrodynamic (MHD) disk wind on disk evolution and dust particle growth. To examine the effect of the MHD disk wind, we compare calculations with and without it. In disk evolution calculations, episodic accretion events (or outbursts) occur repeatedly, as reported in previous studies, regardless of the presence of the MHD disk wind. However, the time interval between outbursts is shorter in cases with the MHD disk wind than in those without it. For the dust particle growth, during the infall phase, there is no significant difference between cases with and without the MHD disk wind, and the dust particles grow to approximately 1–10 cm. Inside the H 2 O snow line, the maximum dust particle size is limited by the collisional fragmentation of the dust particles. Outside the snow line, the maximum dust particle size is primarily determined by radial drift. After the infall phase, when the MHD disk wind is considered, the disk temperature decreases noticeably, and the snow line migrates inward. As a result, the dust particles can grow beyond 10 cm. Therefore, we find that the MHD disk wind plays a crucial role in dust growth and planet formation after the infall phase.}, archive = {J_ApJ}, author = {Yoshihiro Kawasaki and Masahiro N. Machida}, doi = {10.3847/1538-4357/adc67b}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {106}, shortjournal = {The Astrophys. J.}, title = {Impact of magnetohydrodynamic disk wind on early evolutionary stage of protoplanetary disk and dust growth}, volume = {985}, year = {2025}, }
• (2025). Influence of planetary rotation on supersonic flow of lava planets: A two-dimensional horizontal model analysis. ApJ, 985(1), 105. (www)

  @article{ , abstract = {The study of lava planets has attracted significant attention recently because of their close proximity to their host stars, which enhances their detectability for atmospheric characterization. Previous studies showed that the atmospheric flow becomes supersonic if the atmosphere is dominated by rocky vapor evaporated from the magma ocean around the substellar point. These studies often assumed an axisymmetric flow about the axis from the substellar point to the antistellar point but ignored the effect of planetary rotation. However, since the spin rate of lava planets can be rather fast due to their close-in orbits, the aforementioned symmetry may be broken, and significant asymmetric flow is expected. Here, we introduce a two-dimensional framework to explore the influence of planetary rotation on the atmospheric dynamics of these lava planets for the first time, and assess the sensitivity and range of application of our model. Starting from the established one-dimensional axisymmetric atmospheric solution, we obtain the governing equation for the asymmetric flow by expanding with respect to 1/ Ro ( Ro denotes Rossby number and exceeds unity for typical lava planets). The asymmetric component of supersonic flow is pivotal for future research on the observation of these atmospheres, flow patterns of the magma ocean currents driven by atmospheric winds, and deformation of the planetary shape over long timescales.}, archive = {J_ApJ}, author = {Zhuo-Yang Song and Feng Ding and Wanying Kang}, doi = {10.3847/1538-4357/adc80a}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {105}, shortjournal = {The Astrophys. J.}, title = {Influence of planetary rotation on supersonic flow of lava planets: A two-dimensional horizontal model analysis}, volume = {985}, year = {2025}, }
• (2025). Predicting solar flares using a convolutional neural network with extreme-ultraviolet images. ApJ, 985(1), 104. (www)

  @article{ , abstract = {Solar flares, as one of the most intense solar eruptive activities, can bring a destructive impact on the near-Earth space environment and technological infrastructure. Therefore, accurate and real-time forecast of the occurrence of flares is essential to reduce the potential damage to space facilities and navigation systems. Several types of flare forecasting methods have been proposed, e.g., the statistical methods, numerical methods, traditional machine learning, and the recently developed deep leaning. In this paper, we apply one of the deep learning methods, the convolutional neural network ResNet-18, to the tricolor (94, 193, and 304 Å) full-disk extreme-ultraviolet images observed by the Solar Dynamics Observatory Atmospheric Imaging Assembly from 2012 to 2022 with 5 × 24 × 365 × 11 images and 10026 flares ≥ C-class in total to build a solar flare forecasting model to predict whether a flare ≥ C-class would occur within the next m hr ( m = 6, 12, 24, 48, and 72). The values of most performance evaluation metrics scores are over 0.8, with some even exceeding 0.9. The main advantage of this model lies in that it can effectively leverage the historical and spatial information of the source active regions as well as the interaction information from the surrounding active regions or other structures. This information, which cannot be provided by the data from a single active region alone, is demonstrated to be crucial in predicting solar flares. The results show that our prediction model performs well in both short-term and long-term forecasting.}, archive = {J_ApJ}, author = {Yun Yang and Yi Wei Ni and P. F. Chen and Xue Shang Feng}, doi = {10.3847/1538-4357/adc88e}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {104}, shortjournal = {The Astrophys. J.}, title = {Predicting solar flares using a convolutional neural network with extreme-ultraviolet images}, volume = {985}, year = {2025}, }
• (2025). Evolution of alfvén waves in the solar wind. II. broadband driver. ApJ, 985(1), 103. (www)

  @article{ , abstract = {The propagation of azimuthal Alfvén waves and their interaction with the solar wind are investigated using a 2.5D magnetohydrodynamic model that incorporates the effects of optically thin radiation, as well as collisional and collisionless thermal conduction. The background plasma forms a dipole field that is extended into a helmet streamer by the solar wind, with slow wind near the equator and fast wind at mid- and high latitudes. Alfvénic wave trains, localized at random heliographic latitudes, are launched from the coronal base with a moderate amplitude of 9 km s −1 across a wide range of frequencies. Experiments with 100 and 200 events are carried out, resulting in the formation of a cavity where the waves are trapped. The cavity expands or contracts based on the dominant driver period, with longer-period waves setting up larger cavities. A distinctive feature of the cavity is the formation of large-amplitude backward waves that provide an additional push to the solar wind plasma at mid- and high latitudes through the ponderomotive force. We find that episodic and localized wave trains are more efficient at heating and accelerating solar wind plasma compared to continuous monochromatic waves uniformly launched from all heliographic latitudes. Increasing the number of wave events results in enhanced acceleration and heating of the solar wind plasma, as well as suppression of plasmoid breakup events in the equatorial plasma sheet.}, archive = {J_ApJ}, author = {Khaled Alielden and Yeghiazar Taroyan}, doi = {10.3847/1538-4357/adc8a0}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {103}, shortjournal = {The Astrophys. J.}, title = {Evolution of alfvén waves in the solar wind. II. broadband driver}, volume = {985}, year = {2025}, }
• (2025). Exact nonlinear decomposition of ideal-MHD waves using eigenenergies. III. gravity, generalized inhomogeneous quasi-linear partial differential equations, mode conversion, and numerical implementation. ApJ, 985(1), 102. (www)

  @article{ , abstract = {Precise tracking and measurement of the energy carried by the individual magnetohydrodynamic (MHD) modes has important implications and utility in both astrophysical and laboratory plasmas. Previously, this was only achievable in limited linear MHD cases in the β ≪ 1 or β ≫ 1 regimes. In a series of papers, of which this is the third, we introduced the Eigenenergy Decomposition Method (or EEDM) and derived exact analytical expressions for the modal energy components—called eigenenergies—of nonlinear 3D disturbances governed by the homogeneous ideal MHD equations. Here we extend the method to inhomogeneous ideal MHD by introducing a source term accounting for gravity, and we provide detailed guidelines for applying the decomposition scheme to any general inhomogeneous quasi-linear partial differential equations that possess a globally conserved quantity, beyond the realm of MHD. Furthermore, we show that the eigenenergies can be used to locate and measure nonlinear mode conversions, which is an additional feature of the method. Finally, we provide well-categorized context for the application of the method to simulations and discuss the possible numerical inaccuracies that may inevitably arise owing to discretization. This paper provides a more mature description of the method and its interpretation and is recommended as the starting point for readers unfamiliar with the method.}, archive = {J_ApJ}, author = {Axel Raboonik and David I. Pontin and Lucas A. Tarr}, doi = {10.3847/1538-4357/adc917}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {102}, shortjournal = {The Astrophys. J.}, title = {Exact nonlinear decomposition of ideal-MHD waves using eigenenergies. III. gravity, generalized inhomogeneous quasi-linear partial differential equations, mode conversion, and numerical implementation}, volume = {985}, year = {2025}, }
• (2025). JWST observations of the ring nebula (NGC 6720). III. a dusty disk around its central star. ApJ, 985(1), 101. (www)

  @article{ , abstract = {The planetary nebula NGC 6720, also known as the "Ring Nebula," is one of the most iconic examples of nearby planetary nebulae whose morphologies present a challenge to our theoretical understanding of the processes that govern the deaths of most stars in the Universe that evolve on a Hubble time. We present new imaging with JWST of the central star of this planetary nebula (CSPN) and its close vicinity, in the near-to-mid-IR wavelength range. We find the presence of a dust cloud around the CSPN, both from the spectral energy distribution at wavelengths ≳5 μ m as well as from radially extended emission in the 7.7, 10, and 11.3 μ m images. From the modeling of these data, we infer that the CSPN has a luminosity of 310 L ⊙ and is surrounded by a dust cloud with a size of ∼2600 au, consisting of relatively small amorphous silicate dust grains (radius ∼0.01 μ m) with a total mass of 1.9 × 10 −6 M ⊕ . However, our best-fit model shows a significant lack of extended emission at 7.7 μ m—we show that such emission can arise from a smaller (7.3 × 10 −7 M ⊕ ) but uncertain mass of (stochastically heated) ionized polycyclic aromatic hydrocarbon (PAHs). However, the same energetic radiation also rapidly destroys PAH molecules, suggesting that these are most likely being continuously replenished, via the outgassing of cometary bodies and/or the collisional grinding of planetesimals. We also find significant photometric variability of the central source that could be due to the presence of a close dwarf companion of mass ≤0.1 M ⊙ .}, archive = {J_ApJ}, author = {Raghvendra Sahai and Griet Van de Steene and Peter A. M. van Hoof and Albert Zijlstra and Kevin Volk and Harriet L. Dinerstein and Michael J. Barlow and Els Peeters and Arturo Manchado and Mikako Matsuura and Jan Cami and Nick L. J. Cox and Isabel Aleman and Jeronimo Bernard-Salas and Nicholas Clark and Kay Justtanont and Kyle F. Kaplan and Patrick J. Kavanagh and Roger Wesson}, doi = {10.3847/1538-4357/adc91c}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {101}, shortjournal = {The Astrophys. J.}, title = {JWST observations of the ring nebula (NGC 6720). III. a dusty disk around its central star}, volume = {985}, year = {2025}, }
• (2025). The impact of stellar flares on the atmospheric escape of exoplanets orbiting m stars. i. insights from the AU mic system. ApJ, 985(1), 100. (www)

  @article{ , abstract = {The X-ray and extreme ultraviolet (XUV) emission from M stars can drive the atmospheric escape on planets orbiting them. M stars are also known for their frequent emission of stellar flares, which will increase the high-energy flux received by their orbiting planets. To understand how stellar flares impact the primordial atmospheres of planets orbiting young M stars, we use UV spectroscopic data of flares from the Habitable Zones and M dwarf Activity across Time and Measurements of the Ultraviolet Spectral Characteristics of Low-mass Exoplanetary Systems programs as a proxy for the XUV flare emission. Using the software package VPLanet , we simulate the young AU Mic planetary system composed of two Neptune-sized and one Earth-sized planet orbiting a 23 Myr old M1 star. Our findings show that the Earth-sized planet AU Mic d should be in the process of completely losing its atmosphere in the next couple million years, solely due to the quiescent emission, with flares not significantly contributing to its atmospheric escape, due to the small size of AU mic d and its close-in distance from the star. However, our results indicate that flares would play a crucial role for such planets farther away, in the habitable zone (i.e., 0.2935 au) of AU Mic-like stars during the post-saturation phase, accelerating the total atmospheric loss process by a few billion years. For planets between 0.365 au and the HZ outer edge, the additional XUV from flares is necessary to fully deplete primordial atmospheres, since the quiescent emission alone is insufficient.}, archive = {J_ApJ}, author = {Laura N. R. do Amaral and Evgenya L. Shkolnik and R. O. Parke Loyd and Sarah Peacock}, doi = {10.3847/1538-4357/adc932}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {100}, shortjournal = {The Astrophys. J.}, title = {The impact of stellar flares on the atmospheric escape of exoplanets orbiting m stars. i. insights from the AU mic system}, volume = {985}, year = {2025}, }
• (2025). The NANOGrav 15 yr data set: Harmonic analysis of the pulsar angular correlations. ApJ, 985(1), 99. (www)

  @article{ , abstract = {Pulsar timing array observations have found evidence for an isotropic gravitational-wave background with the Hellings–Downs angular correlations between pulsar pairs. This interpretation hinges on the measured shape of the angular correlations, which is predominantly quadrupolar under general relativity. Here we explore a more flexible parameterization: we expand the angular correlations into a sum of Legendre polynomials and use a Bayesian analysis to constrain their coefficients with the 15 yr pulsar timing data set collected by the North American Nanohertz Observatory for Gravitational Waves (NANOGrav). When including Legendre polynomials with multipoles ℓ ≥ 2, we only find a significant signal in the quadrupole with an amplitude consistent with general relativity and nonzero at the ∼95% confidence level and a Bayes factor of 200. When we include multipoles ℓ ≤ 1, the Bayes factor evidence for quadrupole correlations decreases by more than an order of magnitude due to evidence for a monopolar signal at approximately 4 nHz, which has also been noted in previous analyses of the NANOGrav 15 yr data. Further work needs to be done in order to better characterize the properties of this monopolar signal and its effect on the evidence for quadrupolar angular correlations.}, archive = {J_ApJ}, author = {Gabriella Agazie and Akash Anumarlapudi and Anne M. Archibald and Zaven Arzoumanian and Jeremy G. Baier and Paul T. Baker and Bence Bécsy and Laura Blecha and Kimberly K. Boddy and Adam Brazier and Paul R. Brook and Sarah Burke-Spolaor and Rand Burnette and J. Andrew Casey-Clyde and Maria Charisi and Shami Chatterjee and Tyler Cohen and James M. Cordes and Neil J. Cornish and Fronefield Crawford and H. Thankful Cromartie and Kathryn Crowter and Megan E. DeCesar and Paul B. Demorest and Heling Deng and Lankeswar Dey and Timothy Dolch and Elizabeth C. Ferrara and William Fiore and Emmanuel Fonseca and Gabriel E. Freedman and Emiko C. Gardiner and Nate Garver-Daniels and Peter A. Gentile and Kyle A. Gersbach and Joseph Glaser and Deborah C. Good and Kayhan Gültekin and Jeffrey S. Hazboun and Ross J. Jennings and Aaron D. Johnson and Megan L. Jones and David L. Kaplan and Luke Zoltan Kelley and Matthew Kerr and Joey S. Key and Nima Laal and Michael T. Lam and William G. Lamb and Bjorn Larsen and T. Joseph W. Lazio and Natalia Lewandowska and Tingting Liu and Duncan R. Lorimer and Jing Luo and Ryan S. Lynch and Chung-Pei Ma and Dustin R. Madison and Alexander McEwen and James W. McKee and Maura A. McLaughlin and Natasha McMann and Bradley W. Meyers and Patrick M. Meyers and Chiara M. F. Mingarelli and Andrea Mitridate and Jonathan Nay and Cherry Ng and David J. Nice and Stella Koch Ocker and Ken D. Olum and Timothy T. Pennucci and Benetge B. P. Perera and Polina Petrov and Nihan S. Pol and Henri A. Radovan and Scott M. Ransom and Paul S. Ray and Jessie C. Runnoe and Alexander Saffer and Shashwat C. Sardesai and Ann Schmiedekamp and Carl Schmiedekamp and Kai Schmitz and Brent J. Shapiro-Albert and Xavier Siemens and Joseph Simon and Magdalena S. Siwek and Tristan L. Smith and Sophia V. Sosa Fiscella and Ingrid H. Stairs and Daniel R. Stinebring and Kevin Stovall and Abhimanyu Susobhanan and Joseph K. Swiggum and Jacob Taylor and Stephen R. Taylor and Jacob E. Turner and Caner Unal and Michele Vallisneri and Rutger van Haasteren and Sarah J. Vigeland and Haley M. Wahl and Caitlin A. Witt and David Wright and Olivia Young and The NANOGrav Collaboration}, doi = {10.3847/1538-4357/adc997}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {99}, shortjournal = {The Astrophys. J.}, title = {The NANOGrav 15 yr data set: Harmonic analysis of the pulsar angular correlations}, volume = {985}, year = {2025}, }
• (2025). The radiative effects of photochemical hazes on the atmospheric circulation and phase curves of sub-neptunes. ApJ, 985(1), 98. (www)

  @article{ , abstract = {Measuring the atmospheric composition of hazy sub-Neptunes like GJ 1214b through transmission spectroscopy is difficult because of the degeneracy between mean molecular weight (MMW) and haziness. It has been proposed that phase-curve observations can break this degeneracy because of the relationship between MMW and phase-curve amplitude. However, photochemical hazes can strongly affect phase-curve amplitudes as well. We present a large set of general circulation model simulations of the sub-Neptune GJ 1214b that include photochemical hazes with varying atmospheric composition, haze opacity, and haze optical properties. In our simulations, photochemical hazes cause temperature changes of up to 200 K, producing thermal inversions and cooling deeper regions. This results in increased phase-curve amplitudes and adds a considerable scatter to the phase-curve amplitude–metallicity relationship. However, we find that if the haze production rate is high enough to significantly alter the phase curve, the secondary eclipse spectrum will exhibit either emission features or strongly muted absorption features. Thus, the combination of a white-light phase curve and a secondary eclipse spectrum can successfully distinguish between a hazy, lower-MMW and a clear, high-MMW scenario.}, archive = {J_ApJ}, author = {Maria E. Steinrueck and Vivien Parmentier and Laura Kreidberg and Peter Gao and Eliza M.-R. Kempton and Michael Zhang and Kevin B. Stevenson and Isaac Malsky and Michael T. Roman and Emily Rauscher and Matej Malik and Roxana Lupu and Tiffany Kataria and Anjali A. A. Piette and Jacob L. Bean and Matthew C. Nixon}, doi = {10.3847/1538-4357/adc99a}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {98}, shortjournal = {The Astrophys. J.}, title = {The radiative effects of photochemical hazes on the atmospheric circulation and phase curves of sub-neptunes}, volume = {985}, year = {2025}, }
• (2025). Stability of hierarchical triples comprising a central massive body and a tight binary: The effect of inner and outer eccentricities on the binary breakup condition. ApJ, 985(1), 97. (www)

  @article{ , abstract = {We explore the stability of gravitational triple systems comprising a central massive body and a tight binary of less massive pairs. In the present paper, we focus on improving the Hill-type stability criterion for the binary in those systems, with particular attention on the effects of the eccentricities of the inner and outer orbits. We perform direct Newtonian N -body simulations over much longer integration times than previous studies, which is essential to determine the stability and breakup timescale distributions of those systems in a reliable fashion. As a result, we obtain an empirical fitting formula of the binary breakup condition that incorporates effects of the inner and outer eccentricities, the mutual inclination of the inner and outer orbits, the mass ratios of the three bodies, and the breakup timescale.}, archive = {J_ApJ}, author = {Toshinori Hayashi and Alessandro A. Trani and Yasushi Suto}, doi = {10.3847/1538-4357/adc99b}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {97}, shortjournal = {The Astrophys. J.}, title = {Stability of hierarchical triples comprising a central massive body and a tight binary: The effect of inner and outer eccentricities on the binary breakup condition}, volume = {985}, year = {2025}, }
• (2025). Reduced thermal conduction in solar coronal loops. ApJ, 985(1), 96. (www)

  @article{ , abstract = {Thermal conduction plays an important role in the energy balance of the solar coronal plasma. In this paper, we present a new method for deriving observational constraints on the density–temperature relationship for coronal loops from the differential emission measure distributions of active regions and apply the method to measurements obtained with the Extreme-Ultraviolet Imaging Spectrometer on Hinode. Our focus is on coronal loops in the cores of active regions. We show that standard loop models do not reproduce the observed loop-top densities when the variations of cross-sectional area along the loop are taken into account. Nonstandard loop models with reduced thermal conductivity (compared to Spitzer's law) are presented. The modeling results are compared with published measurements of loop parameters obtained with the Soft X-ray Telescope on Yohkoh. We conclude that models with reduced thermal conductivity are better able to reproduce the observed loop-top densities.}, archive = {J_ApJ}, author = {M. Asgari-Targhi and A. A. van Ballegooijen}, doi = {10.3847/1538-4357/adcabc}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {96}, shortjournal = {The Astrophys. J.}, title = {Reduced thermal conduction in solar coronal loops}, volume = {985}, year = {2025}, }
• (2025). The energy content of alfvén waves in the stratified solar atmosphere. ApJ, 985(1), 95. (www)

  @article{ , abstract = {Alfvén waves propagating in a vertically stratified plasma, such as those traveling from the solar photosphere to the corona, are partially reflected due to the gradient in the Alfvén speed. Wave reflection naturally results in the superposition of upward- and downward-propagating waves. A simple analytic model demonstrates that this superposition leads to the nonequipartition of kinetic and magnetic energies in the Alfvén wave perturbations and slows down the net energy transport. A numerical model of Alfvén wave propagation in the lower solar atmosphere reveals significant wave reflection below the transition region, leading to highly variable kinetic and magnetic energy content in the lower chromosphere. At higher altitudes, the kinetic energy eventually dominates, depending on the wave frequency. The velocity at which net energy propagates upward is significantly smaller than the local Alfvén speed throughout the chromosphere. Consequently, the commonly used expression for unidirectional Alfvén waves in a uniform plasma, which relates the energy flux to the kinetic energy density, is not generally applicable in the stratified lower solar atmosphere and cannot be reliably used to estimate the energy content of observed waves. A generalized expression is given, incorporating correction factors that account for wave reflection and energy nonequipartition. The applicability of the expression is discussed.}, archive = {J_ApJ}, author = {Roberto Soler}, doi = {10.3847/1538-4357/adcc2e}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {95}, shortjournal = {The Astrophys. J.}, title = {The energy content of alfvén waves in the stratified solar atmosphere}, volume = {985}, year = {2025}, }
• (2025). MeerKAT 1.3 GHz observations toward the milky way bulge. ApJ, 985(1), 94. (www)

  @article{ , abstract = {We present a MeerKAT survey of portions of the Milky Way bulge. The survey covers 172.8 square degrees in two contiguous mosaics above and below the Galactic center as well as 32 single pointing fields at higher longitudes. The resolution of the images is ∼8 '' at a frequency of 1333 MHz with a typical Stokes I rms of 20 μ Jy beam −1 . Most of the emission seen is from background extragalactic sources, but many compact Galactic objects are identifiable by their polarization properties. Apparent polarized emission resulting from fine-scale Faraday rotation in the interstellar medium is widespread in this region of the Galaxy. The survey is used to search for background giant radio galaxies, >700 kpc in size, identifying 17 such objects. Data products include FITS images of Stokes I , Q , U , and V as well as a Faraday analysis and lists of compact total intensity and polarized sources.}, archive = {J_ApJ}, author = {W. D. Cotton and P. J. Agnihotri and F. Camilo and E. Polisensky and S. D. Hyman}, doi = {10.3847/1538-4357/adcc33}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {94}, shortjournal = {The Astrophys. J.}, title = {MeerKAT 1.3 GHz observations toward the milky way bulge}, volume = {985}, year = {2025}, }
• (2025). Simultaneous existence of the line-locking and velocity shift signatures in quasar SDSS j004613.54+010425.7. ApJ, 985(1), 93. (www)

  @article{ , abstract = {This study presents a detailed investigation of the broad absorption line (BAL) systems in the quasar SDSS J004613.54+010425.7 (hereafter J0046+0104), which makes characters of the simultaneous existence of line-locking and velocity shift signatures. Based on the seven-epoch observed spectra of this source, we explore the variability in equivalent widths, ionization states, locations, velocities, and profile shapes of these BAL systems. Our equivalent width (EW) analysis implies that the outflow clouds in J0046+0104 are in a relatively high ionization state and provides evidence that fluctuations in the ionizing continuum could be a reason for the EW variations of the absorption troughs. Additionally, we observe that the higher-velocity, smoother profile BAL of system A exhibits velocity shifts, whereas the lower-velocity, rougher profile BAL of system B displays line-locking signatures. These findings collectively indicate that velocity shifts typically occur in the inner, more ionized regions of the outflow, whereas line-locking phenomena are manifested in the outer, less ionized regions. Finally, we discuss the possible causes of the observed line-locking and velocity shift signatures.}, archive = {J_ApJ}, author = {Wei-Jian Lu and Ying-Ru Lin}, doi = {10.3847/1538-4357/adce08}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {93}, shortjournal = {The Astrophys. J.}, title = {Simultaneous existence of the line-locking and velocity shift signatures in quasar SDSS j004613.54+010425.7}, volume = {985}, year = {2025}, }
• (2025). Multi-tracer correlated stacking: A novel way to discover anisotropy in nHz stochastic gravitational-wave background. ApJ, 985(1), 92. (www)

  @article{ , abstract = {The isotropic stochastic gravitational-wave background (SGWB) generated by a population of supermassive black hole binaries (SMBHBs) provides a unique window into their cosmic evolution. In addition to the isotropic power spectrum, the anisotropic component of the signal carries additional information about the supermassive black holes (BHs) and host galaxy connection. The measurement of this signal is usually carried out by angular power spectra, which is only a sufficient measure for a Gaussian and statistically isotropic distribution of SMBHBs, where the statistical properties of a field remain unchanged across the sky. In contrast, the contribution from SMBHBs in nHz SGWB will be hosted by fewer massive galaxies, making the nHz background anisotropic and non-Gaussian. As a result, the performance of angular power spectra in extracting the underlying physics is limited. In this work, we propose a novel technique called multi-tracer correlated stacking, which enables the detection of anisotropies in the SGWB by stacking the signal from regions of the sky with tracers of BHs such as active galactic nuclei (AGN), quasars, bright galaxies, etc., that can be mapped up to high redshift. We demonstrate this technique on a simulated population of SMBHBs using an AGN catalog, which maps the underlying matter distribution approximately up to redshift z = 5. This stacking technique uniquely distinguishes between isotropic and anisotropic distributions of SGWB sources, surpassing the capabilities of angular power spectrum-based methods in detecting anisotropic signals. This highlights the effectiveness of this technique in detecting anisotropic SGWB signals, and in the future, this technique can play a crucial role in its discovery.}, archive = {J_ApJ}, author = {Mohit Raj Sah and Suvodip Mukherjee}, doi = {10.3847/1538-4357/adbf92}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {92}, shortjournal = {The Astrophys. J.}, title = {Multi-tracer correlated stacking: A novel way to discover anisotropy in nHz stochastic gravitational-wave background}, volume = {985}, year = {2025}, }
• (2025). Kiloparsec-scale neutral iron kα emission in the starburst-AGN NGC 4945: A relic AGN outflow?. ApJ, 985(1), 91. (www)

  @article{ , abstract = {NGC 4945 contains a well-known heavily obscured active galactic nucleus (AGN) at its core, with prior reports of strong nuclear and off-nuclear neutral Fe K α emission due to the AGN activity. We report the discovery of very extended Fe K α emission with the XMM-Newton EPIC pn in a ∼5 kpc by ∼10 kpc region that is misaligned with the plane of the inclined optical galactic disk by ∼60° in projection. After a careful consideration of the crowded center of the galaxy and numerous unresolved hard X-ray sources present, we estimate that ∼15% of the Fe K α is extended on kiloparsec-sized scales. The overall size and misalignment of the region follows an unusual pattern of radio polarization that is not typical of starbursts or normal disk galaxies but has been interpreted as possibly due to AGN activity. We suggest that the extended Fe K α emission arose from a period of AGN eruption several million years ago—a relic of a past AGN ejection episode.}, archive = {J_ApJ}, author = {Kimberly A. Weaver and Jenna M. Cann and Lynne Valencic and Miranda McCarthy and Ryan W. Pfeifle and K. D. Kuntz and Joel F. Campbell and Kimberly Engle and Ryan Tanner and Edmund Hodges-Kluck and Isabella Carlton}, doi = {10.3847/1538-4357/adc1ce}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {91}, shortjournal = {The Astrophys. J.}, title = {Kiloparsec-scale neutral iron kα emission in the starburst-AGN NGC 4945: A relic AGN outflow?}, volume = {985}, year = {2025}, }
• (2025). Multiwavelength observation of a candidate pulsar halo LHAASO j0621+3755 and the first X-ray detection of PSR j0622+3749. ApJ, 985(1), 90. (www)

  @article{ , abstract = {Pulsar halos are regions around middle-aged pulsars extending out to tens of parsecs. The large extent of the halos and well-defined central cosmic-ray accelerators make this new class of Galactic sources an ideal laboratory for studying cosmic-ray transport. LHAASO J0621+3755 is a candidate pulsar halo associated with the middle-aged gamma-ray pulsar PSR J0622+3749. We observed LHAASO J0621+3755 with VERITAS and XMM-Newton in the TeV and X-ray bands, respectively. For this work, we developed a novel background estimation technique for imaging atmospheric Cherenkov telescope observations of such extended sources. No halo emission was detected with VERITAS (0.3–10 TeV) or XMM-Newton (2–7 keV) within 1 ∘ and 1{0}^{{\prime} } around PSR J0622+3749, respectively. Combined with the LHAASO Kilometer Square Array (KM2A) and Fermi-LAT data, VERITAS flux upper limits establish a spectral break at  ∼1–10 TeV, a unique feature compared with Geminga, the most studied pulsar halo. We model the gamma-ray spectrum and LHAASO-KM2A surface brightness as inverse Compton emission and find suppressed diffusion around the pulsar, similar to Geminga. A smaller diffusion suppression zone and harder electron injection spectrum than Geminga are necessary to reproduce the spectral cutoff. A magnetic field ≤1 μ G is required by our XMM-Newton observation and synchrotron spectral modeling, consistent with Geminga. Our findings support slower diffusion and lower magnetic field around pulsar halos than the Galactic averages, hinting at magnetohydrodynamic turbulence around pulsars. Additionally, we report the detection of an X-ray point source spatially coincident with PSR J0622+3749, whose periodicity is consistent with the gamma-ray spin period of 333.2 ms. The soft spectrum of this source suggests a thermal origin.}, archive = {J_ApJ}, author = {C. B. Adams and A. Archer and P. Bangale and J. T. Bartkoske and W. Benbow and J. H. Buckley and Y. Chen and J. L. Christiansen and A. J. Chromey and A. Duerr and M. Errando and M. Escobar Godoy and A. Falcone and S. Feldman and Q. Feng and L. Fortson and A. Furniss and W. Hanlon and O. Hervet and C. E. Hinrichs and J. Holder and T. B. Humensky and W. Jin and M. N. Johnson and P. Kaaret and M. Kertzman and M. Kherlakian and D. Kieda and T. K. Kleiner and N. Korzoun and F. Krennrich and S. Kumar and S. Kundu and M. J. Lang and M. Lundy and G. Maier and M. J. Millard and J. Millis and C. L. Mooney and P. Moriarty and R. Mukherjee and W. Ning and R. A. Ong and A. Pandey and M. Pohl and E. Pueschel and J. Quinn and P. L. Rabinowitz and K. Ragan and P. T. Reynolds and D. Ribeiro and L. Rizk and E. Roache and I. Sadeh and L. Saha and G. H. Sembroski and R. Shang and M. Splettstoesser and D. Tak and A. K. Talluri and J. V. Tucci and J. Valverde and D. A. Williams and S. L. Wong and J. Woo and (VERITAS collaboration) and Jon Kwong and Kaya Mori and Charles J. Hailey and Samar Safi-Harb and Shuo Zhang and Naomi Tsuji and (XMM-Newton collaboration) and Silvia Manconi and Fiorenza Donato and Mattia Di Mauro}, doi = {10.3847/1538-4357/adc92b}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {90}, shortjournal = {The Astrophys. J.}, title = {Multiwavelength observation of a candidate pulsar halo LHAASO j0621+3755 and the first X-ray detection of PSR j0622+3749}, volume = {985}, year = {2025}, }
• (2025). Evidence of extreme-ultraviolet resonant excitation in the middle corona during a solar flare. ApJ, 985(1), 89. (www)

  @article{ , abstract = {We present observations of an eruptive solar flare on 2016 January 6 that occurred behind the solar limb from the perspective of the Earth, but was well observed by the Solar-Terrestrial Relations Observatory (or STEREO) and the Solar Extreme Ultraviolet Monitor on NASA's Mars Atmosphere and Volatile EvolutioN (MAVEN) mission. Light curves showing the evolution of the flare's irradiance as a function of time taken by MAVEN are well correlated with the brightness evolution of fan structures observed in the Project for On-Board Autonomy 2's Sun Watcher with Active Pixels and Image Processing (SWAP) 174 Å passband, suggesting that the radiance of structures near the flare site was influenced by emission from the flare. Because SWAP did not directly observe the flare itself, this event represents a rare opportunity to study the evolution of emission near a flare without the risk of instrumental scattered light contaminating the observations. We analyze this evolution and implement a simple model to explore the possibility that resonant excitation (RE, also known as resonant scattering) plays an important role in driving coronal extreme-ultraviolet (EUV) emission during flaring events. Our modeling shows that for a large flare, RE could increase emission from nearby structures by about 45%, consistent with our findings that the involved structures observed by SWAP increased in brightness by about 60% during the flare. We conclude that RE may play an important role in driving coronal EUV emission under certain circumstances and should be accounted for in models and emission-based analysis tools.}, archive = {J_ApJ}, author = {Daniel B. Seaton and Cooper Downs and Giulio Del Zanna and Matthew J. West and Edward M. B. Thiemann and Amir Caspi and Edward E. DeLuca and Leon Golub and James Paul Mason and Ritesh Patel and Katharine K. Reeves and Yeimy J. Rivera and Sabrina L. Savage}, doi = {10.3847/1538-4357/adcab5}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {89}, shortjournal = {The Astrophys. J.}, title = {Evidence of extreme-ultraviolet resonant excitation in the middle corona during a solar flare}, volume = {985}, year = {2025}, }
• (2025). Comparing observed properties of winds in low-luminosity active galactic nuclei with theoretical predictions. ApJ, 985(1), 88. (www)

  @article{ , abstract = {Theoretical and numerical simulations of black hole hot accretion flows have shown the ubiquitous existence of winds and predicted their properties, such as velocity and mass flux. In this paper, we have summarized from the literature the physical properties of winds launched from low-luminosity active galactic nuclei (LLAGN), which are believed to be powered by hot accretion flows, and compared them with theoretical predictions. We infer that for both ultrafast outflows and hot winds, the observed wind velocity as a function of their launching radius and the ratio between wind mass flux and black hole accretion rate show good consistency with theoretical predictions. For the prototype LLAGN M81* with abundant observational data, we have examined various observed properties of wind in detail, including velocity, mass flux of the wind, the power-law index of the radial profile of inflow rate, and the jet-to-wind power ratio. Good agreements are found with theoretical predictions, providing strong support to the theory of wind launched from hot accretion flows.}, archive = {J_ApJ}, author = {Fangzheng Shi and Feng Yuan and Francesco Tombesi and Fu-guo Xie}, doi = {10.3847/1538-4357/adcc17}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {88}, shortjournal = {The Astrophys. J.}, title = {Comparing observed properties of winds in low-luminosity active galactic nuclei with theoretical predictions}, volume = {985}, year = {2025}, }
• (2025). From tides to currents: Unraveling the mechanism that powers WASP-107b’s internal heat flux. ApJ, 985(1), 87. (www)

  @article{ , abstract = {The sub-Jovian exoplanet WASP-107b ranks among the best-characterized low-density worlds, featuring a Jupiter-like radius and a mass that lies firmly in the sub-Saturn range. Recently obtained JWST spectra reveal significant methane depletion in the atmosphere, indicating that WASP-107b's envelope has both a high metallicity and an elevated internal heat flux. Together with a detected nonzero orbital eccentricity, these data have been interpreted as evidence of tidal heating. However, explaining the observed luminosity with tidal dissipation requires an unusually low tidal quality factor of Q ∼ 100. Moreover, we find that secular excitation by the radial-velocity-detected outer companion WASP-107c generally cannot sustain WASP-107b's eccentricity in steady state against tidal circularization. As an alternative explanation, we propose that ohmic dissipation—generated by interactions between zonal flows and the planetary magnetic field in a partially ionized atmosphere—maintains the observed thermal state. Under nominal assumptions for the field strength, atmospheric circulation, and ionization chemistry, we show that ohmic heating readily accounts for WASP-107b's inflated radius and anomalously large internal entropy.}, archive = {J_ApJ}, author = {Konstantin Batygin}, doi = {10.3847/1538-4357/adccc4}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {87}, shortjournal = {The Astrophys. J.}, title = {From tides to currents: Unraveling the mechanism that powers WASP-107b’s internal heat flux}, volume = {985}, year = {2025}, }
• (2025). The environmental quenching mechanisms of field dwarf galaxies. ApJ, 985(1), 86. (www)

  @article{ , abstract = {Field dwarf galaxies not actively forming stars are relatively rare in the local Universe, but are present in cosmological hydrodynamical simulations. We use the TNG50 simulation to investigate their origin and find that they all result from environmental effects that have removed or reduced their gas content. Quenched field dwarfs consist of either backsplash objects ejected from a massive host or of systems that have lost their gas after crossing overdense regions such as filaments or sheets ("cosmic web stripping"). Quenched fractions rise steeply with decreasing stellar mass, with quenched systems making up roughly ∼15% of all field dwarfs (i.e., excluding satellites) with stellar masses 10 7 < M ⋆ / M ⊙ < 10 9 . This fraction drops to only ∼1% when a strict isolation criterion that requires no neighbors with M ⋆ > 10 9 M ⊙ within 1.5 Mpc is applied. Of these isolated dwarfs, ∼6% are backsplash, while the other ∼94% have been affected by the cosmic web. Backsplash systems are more deficient in dark matter, have retained less or no gas, and have stopped forming stars earlier than cosmic web-stripped systems. The discovery of deeply isolated dwarf galaxies that were quenched relatively recently would lend observational support to the prediction that the cosmic web is capable of inducing the cessation of star formation in dwarfs.}, archive = {J_ApJ}, author = {José A. Benavides and Julio F. Navarro and Laura V. Sales and Isabel Pérez and Bahar Bidaran}, doi = {10.3847/1538-4357/adced0}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {86}, shortjournal = {The Astrophys. J.}, title = {The environmental quenching mechanisms of field dwarf galaxies}, volume = {985}, year = {2025}, }
• (2025). Large-scale field-aligned flows in the heliosheath. ApJ, 985(1), 85. (www)

  @article{ , abstract = {We use a state-of-the-art 3D MHD simulation to show that large-scale thermal pressure gradients in the heliosheath drive suprathermal particles (pickup ions with 1–5 keV) to stream along magnetic field lines faster than the cold bulk solar wind. Large-scale pressure gradients between the nose and flank of the heliopause stem from neutrals flowing in from the nose direction. Hybrid simulations suggest that these gradients will also drive field-aligned flows at higher energies (5–30 keV). The field-aligned flows are stronger within 10 au of the termination shock, where the magnetic field lines in the upwind hemisphere have shorter path lengths in the heliosheath before connecting back to the termination shock. This mechanism explains the large field-aligned flows seen in the data in the first 2.5 yr of heliosheath data when Voyager 2 was above the heliospheric current sheet. This work has implications for how the bulk flows are derived in Voyager 1 from the Compton–Getting effect, where particles at all energies are assumed to move with the same speed.}, archive = {J_ApJ}, author = {Merav Opher and Marc Kornbleuth and Rob Decker and John Richardson and Ethan Bair and Kostas Dialynas and Romina Nikoukar and Matthew E. Hill and Senbei Du and Vladimir Florinski}, doi = {10.3847/1538-4357/adced5}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {85}, shortjournal = {The Astrophys. J.}, title = {Large-scale field-aligned flows in the heliosheath}, volume = {985}, year = {2025}, }
• (2025). A multiline analysis of the distribution and excitation of CS and H2CS in the HD 163296 disk. ApJ, 985(1), 84. (www)

  @article{ , abstract = {The abundance and distribution of sulfur-bearing molecules in protoplanetary disks directly influence the composition and potential habitability of nascent planets in addition to providing powerful probes of the physical gas conditions in the disks themselves. Here, we present new and archival Atacama Large Millimeter/submillimeter Array and Submillimeter Array observations of CS and H 2 CS, and their C 34 S and H 2 C 34 S isotopologues, at high angular resolution (≈0 \mathop{.}\limits^{^{\prime\prime} } 2–0 \mathop{.}\limits^{^{\prime\prime} } 4; 20–40 au) in the HD 163296 disk, which reveal a central cavity and multiringed emission structure. These observations comprise the most comprehensive, multiline CS data in a planet-forming disk to date, spanning a wide range of excitation conditions from E u = 7.1 to 129.3 K, and include new detections of C 34 S, H 2 CS, and H 2 C 34 S in this system. Using these data, we derive spatially resolved rotational temperature and column density profiles for all species. We find a column density ratio N (H 2 CS)/ N (CS) ≈ 0.5, which is comparable to that of the similar MWC 480 disk and suggests that organic sulfur compounds may constitute a large fraction of the volatile sulfur reservoir in disks around Herbig stars generally. We derive 32 S/ 34 S ratios of ≈5 (CS/C 34 S) and ≈2 (H 2 CS/H 2 C 34 S) based on disk-averaged and spatially resolved analyses. Both values are consistent across these two pairs of optically thin molecules and are well below the expected ratio in the interstellar medium of ≈22, suggesting significant sulfur fractionation. We also constrain the CS emitting layer ( z / r ≲ 0.1) using the vertical separations of the disk surfaces in the channel maps and based on the known 2D gas structure of the HD 163296 disk combined with our excitation analysis.}, archive = {J_ApJ}, author = {Charles J. Law and Romane Le Gal and Yoshihide Yamato and Ke Zhang and Viviana V. Guzmán and Claudio Hernández-Vera and L. Ilsedore Cleeves and Greta Guidi and Alice S. Booth}, doi = {10.3847/1538-4357/adc304}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {84}, shortjournal = {The Astrophys. J.}, title = {A multiline analysis of the distribution and excitation of CS and H2CS in the HD 163296 disk}, volume = {985}, year = {2025}, }
• (2025). Metallicity scatter originating from subkiloparsec starbursting clumps in the core of a protocluster at z = 7.88. ApJ, 985(1), 83. (www)

  @article{ , abstract = {We present new JWST NIRSpec integral field unit (IFU) G395H/F290LP observations of a merging galaxy system at z = 7.88, part of A2744-z7p9OD, the most distant protocluster to date. The IFU cube reveals [O iii ] λ 5007 emissions in two previously known galaxies, ZD3 and ZD6, and a newly identified galaxy, ZD12, at z spec = 7.8762. One of the detected [O iii ]-emitting regions has a detection of the auroral [O iii ] λ 4363 line, allowing us to derive a direct metallicity of {\rm{log}}({\rm{O}}/{\rm{H}}) + 12 = 7.4 ± 0.2, while metallicities in other regions are measured using strong-line calibration methods. We find large deviations within the measured metallicity ( {\rm{\Delta }}\mathrm{log}({\rm{O}}/{\rm{H}})\sim 1 ), which suggests a fast chemical enrichment from intense star formation and merger-driven growth, as expected in early galaxies. Our analysis shows that metal-poor regions could easily be outshone by more enriched regions, posing a challenge for spectroscopic analysis based on integrated light (i.e., NIRSpec/MSA) against identifying metal-free star formation in the early Universe. NIRCam imaging reveals seven UV-bright clumps in ZD12, in a stellar mass range of \mathrm{log}{M}_{* }/{M}_{\odot }\sim 7.6 –8.9. Four of them are unresolved (≲100 pc) and intensely star-forming (>30 M ⊙ yr −1 kpc −2 ), likely contributing to the scatter in metallicity by producing an ideal environment for rapid chemical cycles. Lastly, we revisit the nature of the host protocluster by including new member galaxies identified here and in the literature, and obtain a local overdensity factor \delta =4{4}_{-31}^{+89} , a total halo mass {M}_{{\rm{h}}}=5.{8}_{-0.3}^{+0.2}\times 1{0}^{11}\,{M}_{\odot } , and a formal velocity dispersion 1100  ±  500 km s −1 .}, archive = {J_ApJ}, author = {Takahiro Morishita and Massimo Stiavelli and Eros Vanzella and Pietro Bergamini and Kristan Boyett and Marco Chiaberge and Claudio Grillo and Nicha Leethochawalit and Matteo Messa and Guido Roberts-Borsani and Piero Rosati and Anowar J. Shajib}, doi = {10.3847/1538-4357/adc4c3}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {83}, shortjournal = {The Astrophys. J.}, title = {Metallicity scatter originating from subkiloparsec starbursting clumps in the core of a protocluster at z = 7.88}, volume = {985}, year = {2025}, }
• (2025). Physics-based simulation of the 2013 april 11 solar energetic particle event. ApJ, 985(1), 82. (www)

  @article{ , abstract = {Solar energetic particles (SEPs) can pose hazardous radiation risks to both humans and spacecraft electronics in space. Numerical modeling based on first principles offers valuable insights into the underlying physics of SEPs and provides synthetic observables for SEPs at any time and location in the inner heliosphere. In this work, we present a numerical scheme, which conserves the number of particles based on integral relations for Poisson brackets, to solve the kinetic equation for particle acceleration and transport processes. We implement this scheme within the Space Weather Modeling Framework, developed at the University of Michigan. In addition, we develop a new shock-capturing tool to study the coronal mass ejection-driven shock originating from the low solar corona. These methodological advancements are applied to conduct a comprehensive study of a historical SEP event on 2013 April 11. Observations from multiple spacecraft, including the Solar and Heliospheric Observatory, Solar Dynamics Observatory, Geostationary Operational Environmental Satellite, Advanced Composition Explorer near Earth, and STEREO-A/B, are used for model–data comparison and validation. We show synthetic observables, including extreme ultraviolet and white-light images, proton time–intensity profiles, and energy spectra, and discuss their differences and probable explanations compared to observations. Our simulation results demonstrate the application of the Poisson bracket scheme with a particle solver to simulating a historical SEP event. We also show the capability of extracting the complex shock surface using our shock-capturing tool and understand how the complex shock surface affects the particle acceleration process.}, archive = {J_ApJ}, author = {Weihao Liu and Igor V. Sokolov and Lulu Zhao and Tamas I. Gombosi and Nishtha Sachdeva and Xiaohang Chen and Gábor Tóth and David Lario and Ward B. Manchester and Kathryn Whitman and Christina M. S. Cohen and Alessandro Bruno and M. Leila Mays and Hazel M. Bain}, doi = {10.3847/1538-4357/adc4e3}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {82}, shortjournal = {The Astrophys. J.}, title = {Physics-based simulation of the 2013 april 11 solar energetic particle event}, volume = {985}, year = {2025}, }
• (2025). Virgo filaments. v. disrupting the baryon cycle in the NGC 5364 galaxy group. ApJ, 985(1), 81. (www)

  @article{ , abstract = {The Virgo Filament Survey (VFS) is a comprehensive study of galaxies that reside in the extended filamentary structures surrounding the Virgo Cluster, out to 12 virial radii. The primary goal is to characterize all of the dominant baryonic components within galaxies and to understand whether and how they are affected by the filament environment. A key constituent of VFS is a narrowband H α imaging survey of over 600 galaxies, VFS-H α . The H α images reveal detailed, resolved maps of the ionized gas and massive star formation. This imaging is particularly powerful as a probe of environmentally induced quenching because different physical processes affect the spatial distribution of star formation in different ways. In this paper, we present the first results from the VFS-H α for the NGC 5364 group, a low-mass ( {\mathrm{log}}_{10}({M}_{\mathrm{dyn}}/{M}_{\odot })\lt 13 ) system located at the western edge of the Virgo III filament. We combine H α imaging with resolved H i observations from MeerKAT for eight group members. These galaxies exhibit peculiar morphologies, including strong distortions in the stars and the gas, truncated H i and H α disks, H i tails, extraplanar H α emission, and off-center H α emission. These signatures are suggestive of environmental processing such as tidal interactions, ram pressure stripping, and starvation. We quantify the role of ram pressure stripping expected in this group, and find that it can explain the cases of H i tails and truncated H α for all but one of the disk-dominated galaxies. Our observations indicate that multiple physical mechanisms are disrupting the baryon cycle in these group galaxies.}, archive = {J_ApJ}, author = {Rose A. Finn and Gregory Rudnick and Pascale Jablonka and Mpati Ramatsoku and Gautam Nagaraj and Benedetta Vulcani and Rebecca A. Koopmann and Matteo Fossati and James Agostino and Yannick Bahé and Santiago Garcia-Burillo and Gianluca Castignani and Francoise Combes and Kim Conger and Gabriella De Lucia and Vandana Desai and John Moustakas and Dara Norman and Damien Sperone-Longin and Melinda Townsend and Lizhi Xie and Daria Zakharova and Dennis Zaritsky}, doi = {10.3847/1538-4357/adc566}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {81}, shortjournal = {The Astrophys. J.}, title = {Virgo filaments. v. disrupting the baryon cycle in the NGC 5364 galaxy group}, volume = {985}, year = {2025}, }
• (2025). The BoRG-JWST survey: Abundance and mass-to-light ratio of luminous z = 7–9 galaxies from independent sight lines with NIRSpec. ApJ, 985(1), 80. (www)

  @article{ , abstract = {We present new results on the rest-frame UV luminosity function (UVLF) and stellar mass-to-light ( M / L ) ratio of bright ( M UV ≲ −20 mag) spectroscopically confirmed galaxies at z = 7–9 derived from the BoRG-JWST survey, a unique data set of NIRSpec prism follow-up of Hubble Space Telescope (HST)–selected sources from random-pointing imaging. By selecting galaxies from over 300 independent sight lines, the survey minimizes cosmic variance, ensuring a statistically robust sample of the bright-galaxy population during the epoch of reionization. The data are used to constrain, for the first time, the bright end of the UVLF at z = 7–9 from spectroscopically confirmed galaxies over eight independent fields. We find that the bright end of the UVLF is higher than found using imaging over JWST legacy fields, suggesting that the latter may be significantly affected by cosmic variance, and thus reducing the tension with recent findings from JWST at z > 10 and comparable to models invoking little dust attenuation and bursty star formation. Additionally, we use the galaxies' JWST spectra to infer their stellar masses and M / L ratios relative to other HST and JWST studies. We show that the stellar mass scales almost linearly with UV luminosity ( M {}_{* }\propto {L}_{{\rm{UV}}}^{0.85\pm 0.12} ), albeit with large (∼0.5 dex) intrinsic scatter, consistent with stochastic bursts of star formation in early galaxy formation.}, archive = {J_ApJ}, author = {Sofía Rojas-Ruiz and Micaela Bagley and Guido Roberts-Borsani and Tommaso Treu and Steven L. Finkelstein and Takahiro Morishita and Nicha Leethochawalit and Charlotte Mason and Eduardo Bañados and Michele Trenti and Massimo Stiavelli and L. Y. Aaron Yung and Pablo Arrabal Haro and Rachel S. Somerville and Christian Soto}, doi = {10.3847/1538-4357/adc67d}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {80}, shortjournal = {The Astrophys. J.}, title = {The BoRG-JWST survey: Abundance and mass-to-light ratio of luminous z = 7–9 galaxies from independent sight lines with NIRSpec}, volume = {985}, year = {2025}, }
• (2025). Recovering pulsar braking index from a population of millisecond pulsars. ApJ, 985(1), 79. (www)

  @article{ , abstract = {The braking index, n , of a pulsar is a measure of its angular momentum loss and the value it takes to correspond to different spin-down mechanisms. For a pulsar spinning down due to gravitational-wave emission from the principal mass quadrupole mode alone, the braking index would equal exactly 5. Unfortunately, for millisecond pulsars, it can be hard to measure observationally due to the extremely small second time derivative of the rotation frequency, \ddot{f} . This paper aims to examine whether it could be possible to extract the distribution of n for a whole population of pulsars rather than measuring the values individually. We use simulated data with an injected n = 5 signal for 47 ms pulsars and extract the distribution using hierarchical Bayesian inference methods. We find that while possible, observation times of over 20 yr and rms noise of the order of 10 −5 ms are needed, which can be compared to the mean noise value of 3 × 10 −4 ms for the recent wide-band 12.5 yr NANOGrav sample, which provided the pulsar timing data used in this paper.}, archive = {J_ApJ}, author = {A. L. Hewitt and M. Pitkin and I. M. Hook}, doi = {10.3847/1538-4357/adc683}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {79}, shortjournal = {The Astrophys. J.}, title = {Recovering pulsar braking index from a population of millisecond pulsars}, volume = {985}, year = {2025}, }
• (2025). Gravity-selected cluster samples: A new take on the compton-y–Mass relation. ApJ, 985(1), 78. (www)

  @article{ , abstract = {We investigate the scaling relation between the Compton- y parameter and mass in a gravity-selected sample of galaxy clusters, selected based on their gravitational lensing effects on background galaxies. Unlike intracluster medium (ICM)−selected samples, gravity-selected clusters do not require corrections for selection biases in ICM properties, such as Compton- y , since these properties are not used for selection. Our sample consists of 13 gravity-selected clusters with weak-lensing signal-to-noise ratios greater than 7 and redshifts in the range 0.1 < z < 0.4, drawn from the peak catalog of shear-selected clusters in M. Oguri et al. We determined spectroscopic redshifts using Sloan Digital Sky Survey spectroscopy, derived tangential radial profiles from Hyper Suprime-Cam shear data, and calculated cluster masses by fitting a Navarro, Frenk, & White profile. Compton- y measurements were obtained from Atacama Cosmology Telescope maps. Our sample reveals a broader scatter in the Compton- y –mass scaling relation compared to ICM-selected samples, even after accounting for selection effects and mass bias of the latter, which we find to be (1 − b ) = 0.72 ± 0.09. Additionally, we identify a second population of clusters with unusually small Compton- y for their mass, which is absent in ICM-selected samples. This second population composes 1{3}_{-8}^{+10} % of the entire sample, with O19 currently being the only secure representative.}, archive = {J_ApJ}, author = {S. Andreon and M. Radovich}, doi = {10.3847/1538-4357/adc71e}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {78}, shortjournal = {The Astrophys. J.}, title = {Gravity-selected cluster samples: A new take on the compton-y–Mass relation}, volume = {985}, year = {2025}, }
• (2025). Late-time evolution and instabilities of tidal disruption disks. ApJ, 985(1), 77. (www)

  @article{ , abstract = {Observations of tidal disruption events on timescales of years after the main flare show evidence of continued activity in the form of optical/UV emission, quasiperiodic eruptions, and delayed radio flares. Motivated by this, we explore the time evolution of these disks, using semi-analytic models to follow the changing disk properties and feeding rate to the central black hole. We find that thermal instabilities typically begin ∼100 days after the TDE, causing the disk to cycle between high and low accretion states for up to ∼10 yr. The high state is super-Eddington, which may be associated with outflows that eject ∼10 −3 –10 −1 M ⊙ over ∼1–2 days, with a range of velocities ∼0.03–0.3 c . Collisions between these mass ejections may cause radio flares. In the low state, the accretion rate slowly grows over months to years, as continued fallback accretion builds the disk's mass. In this phase, the disk has a luminosity of ∼10 41 –10 42 erg s −1 in the optical/UV, as seen in some late-time observations. Although the accretion cycles we find occur for a typical α -disk, in nature, the disk could be stabilized by other effects, such as the disk's magnetic field or heating from fallback accretion, the latter of which we explore. Thus, higher-cadence optical/UV observations along with joint radio monitoring will be key for following the disk state and testing these models.}, archive = {J_ApJ}, author = {Anthony L. Piro and Brenna Mockler}, doi = {10.3847/1538-4357/adc729}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {77}, shortjournal = {The Astrophys. J.}, title = {Late-time evolution and instabilities of tidal disruption disks}, volume = {985}, year = {2025}, }
• (2025). Properties of interstellar medium in the s0 galaxy NGC 1222: Evidence for shock-enhanced line emission. ApJ, 985(1), 76. (www)

  @article{ , abstract = {In this paper, we present a comprehensive study on the properties of the interstellar medium in NGC 1222, a star-forming early-type merging galaxy that forms a triple system, using optical and far-infrared spectroscopic, and multiband photometric data. The fit to the spectral energy distribution reveals a high dust content in the galaxy, with a dust-to-stellar mass ratio of M dust / M ⋆ ∼ 3.3 × 10 −3 that is 40–90 times larger than the mean value of local S0 galaxies. By comparing the observed optical emission line ratios to shock models, we suggest that a merger-induced shock, which is further supported by the higher-than-average [O i ] 63 μ m- and [C ii ] 158 μ m-to-PAH ratios, plays a role in heating the gas in NGC 1222. We also show evidence for gas inflow by analyzing the kinematic properties of NGC 1222.}, archive = {J_ApJ}, author = {Jiamin Liu and Yinghe Zhao and Kai-Xing Lu and Jin-Ming Bai}, doi = {10.3847/1538-4357/adc732}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {76}, shortjournal = {The Astrophys. J.}, title = {Properties of interstellar medium in the s0 galaxy NGC 1222: Evidence for shock-enhanced line emission}, volume = {985}, year = {2025}, }
• (2025). Investigating the variable continuum lags in PG 2130+099. ApJ, 985(1), 75. (www)

  @article{ , abstract = {Broadband photometric reverberation mapping (RM) provides a measure of the size of the continuum-emitting region in active galactic nuclei (AGN). Previous monitoring campaigns of PG 2130+099 disagree as to whether the continuum-emitting region size is consistent with that predicted for a standard optically thick and geometrically thin accretion disk. We present ∼6 months of observations from several robotic telescopes, providing the highest-cadence and widest-wavelength coverage photometric RM study of PG 2130+099 to date. Our results indicate that the inferred size of the continuum-emitting region in PG 2130+099, like many recently observed AGN, is larger than the simplest predictions for an irradiated geometrically thin, optically thick accretion disk. We also perform a flux–flux analysis, finding a variable spectrum broadly consistent with a disk, and a constant component with enhanced i -band emission, potentially due to H α . We find some evidence of increasing lag with luminosity, but previous lag measurements are too uncertain to be definitive.}, archive = {J_ApJ}, author = {Jake A. Miller and Edward M. Cackett and Mike Goad and Kirk T. Korista}, doi = {10.3847/1538-4357/adc80c}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {75}, shortjournal = {The Astrophys. J.}, title = {Investigating the variable continuum lags in PG 2130+099}, volume = {985}, year = {2025}, }
• (2025). Implications of fermionic dark matter interactions on anisotropic neutron stars. ApJ, 985(1), 74. (www)

  @article{ , abstract = {The presence of dark matter (DM) within a neutron star (NS) can substantially influence the macroscopic properties. It is commonly assumed that the pressure inside an NS is isotropic, but in reality, pressure is locally anisotropic. This study explores the properties of anisotropic NS with a subfraction of DM (isotropic) trapped inside. Implementing a two-fluid formalism with three distinct classes of equation of state: AP3 (a realistic nucleon–nucleon interaction model), BSk22 (modeling atomic nuclei and neutron matter), and MPA1 (considering relativistic effects in nuclear interactions). The properties of NS, such as mass ( M ), radius ( R ), and dimensionless tidal deformability (Λ), for various DM-anisotropic configurations, have been rigorously tested against observational constraints. These constraints include data from the binary NS merger GW170817, NICER X-ray measurements, and pulsar mass–radius observations. We observe that with increasing DM subfraction, higher anisotropies could also satisfy the observational constraints for Yukawa coupling strength g = 10 −5 , which satisfies the DM self-interaction cross-section ( σ ) i.e 0.1–10 cm −2 g −1 . Furthermore, increasing the coupling ( g ) between DM and its mediator leads to the formation of a core–halo structure, with a DM halo surrounding the baryonic matter. Specifically, for coupling values of g = 10 −4 , 10 −3.7 , and 10 −3.5 , we observe that the maximum radius ( R max ) decreases with increasing anisotropy, which contrasts with the behavior at g = 10 −5 and in scenarios with no DM. Our analysis indicates that binary pulsar systems could potentially constrain the extent of admixed anisotropic NS or, more optimistically, provide evidence for the existence of DM-admixed anisotropic NS.}, archive = {J_ApJ}, author = {Premachand Mahapatra and Chiranjeeb Singha and Ayush Hazarika and Prasanta Kumar Das}, doi = {10.3847/1538-4357/adc918}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {74}, shortjournal = {The Astrophys. J.}, title = {Implications of fermionic dark matter interactions on anisotropic neutron stars}, volume = {985}, year = {2025}, }
• (2025). Investigating bidirectional flows in a quiescent prominence using MAST ca II 8542 Å line scan observations. ApJ, 985(1), 73. (www)

  @article{ , abstract = {Quiescent prominences are large magnetic structures hosting cool plasma in surrounding million-degree solar coronae. Prominences host different flows that may distort magnetic field lines, which may lead to magnetic reconnection inside the prominence body. In this study, we investigate bidirectional flow patches in a quiescent prominence. The investigation included the analysis of velocities in the line of sight (LOS) and the plane of sky (POS) of the prominence, complemented with intensity at different spectral positions of the Ca II 8542 Å line. The LOS velocities were obtained using Gaussian fitting to the observed Ca II spectra, whereas the POS velocities were derived from a position−time diagram along a vertical slit in the region of interest (ROI). Complementary to Ca II 8542 Å line scans, EUV intensity images from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory were analyzed to investigate the multithermal nature of the observed bidirectional flows. Out of two ROIs, in the first ROI, a large central patch of bidirectional flow was present initially that merged with other patches and disappeared approximately 30 minutes from the beginning, followed by the generation of another set of patches. Cospatial with diverging LOS motions of order 10 km s −1 associated with patch dynamics, POS motions of similar order were also observed in the ROI. Diverging intensity enhancements in different AIA channels, indicating a multithermal nature of bidirectional flows, were observed cospatially with diverging flows in the POS. Similar dynamics were observed in the second ROI. Bidirectional flow patches and the associated dynamics in LOS and POS may be related to magnetic reconnection inside the prominence.}, archive = {J_ApJ}, author = {Sandeep K. Dubey and Andrew Hillier and Shibu K. Mathew}, doi = {10.3847/1538-4357/adc91a}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {73}, shortjournal = {The Astrophys. J.}, title = {Investigating bidirectional flows in a quiescent prominence using MAST ca II 8542 Å line scan observations}, volume = {985}, year = {2025}, }
• (2025). XUE: Thermochemical modeling suggests a compact and gas-depleted structure for a distant, irradiated protoplanetary disk. ApJ, 985(1), 72. (www)

  @article{ , abstract = {Unveiling the physical structure of protoplanetary disks is crucial for interpreting the diversity of the exoplanet population. Until recently, the census of the physical properties of protoplanetary disks probed by mid-infrared observations was limited to the solar neighborhood ( d ≲ 250 pc). However, nearby star-forming regions (SFRs) such as Taurus—where no O-type stars reside—are not representative of the environments where the majority of the planet formation occurs in the Galaxy. The James Webb Space Telescope (JWST) now enables observations of disks in distant high-mass SFRs, where strong external far-ultraviolet radiation is expected to impact those disks. Nevertheless, a detailed characterization of the population of externally irradiated disks is still lacking. We use the thermochemical code ProDiMo to model JWST/MIRI spectroscopy and archival visual/near-infrared photometry aiming to constrain the physical structure of the irradiated disk around the solar-mass star XUE 1 in NGC 6357 ( d ≈ 1690 pc). Our findings are as follows. (1) Mid-infrared dust emission features are explained by amorphous and crystalline silicates with compositions similar to nearby disks. (2) The molecular features detected with MIRI originate within the first ∼1 au, consistent with results from slab models. (3) Our model favors a disk truncated at 10 au with a gas-to-dust ratio of unity in the outskirts. (4) Comparing models of the same disk structure under different irradiation levels, we find that strong external irradiation raises gas temperature tenfold and boosts water abundance beyond 10 au by a factor of 100.}, archive = {J_ApJ}, author = {Bayron Portilla-Revelo and Konstantin V. Getman and María Claudia Ramírez-Tannus and Thomas J. Haworth and Rens Waters and Arjan Bik and Eric D. Feigelson and Inga Kamp and Sierk E. van Terwisga and Jenny Frediani and Thomas Henning and Andrew J. Winter and Veronica Roccatagliata and Thomas Preibisch and E. Sabbi and Peter Zeidler and Michael A. Kuhn}, doi = {10.3847/1538-4357/adc91d}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {72}, shortjournal = {The Astrophys. J.}, title = {XUE: Thermochemical modeling suggests a compact and gas-depleted structure for a distant, irradiated protoplanetary disk}, volume = {985}, year = {2025}, }
• (2025). Oligarchic growth of protoplanets in planetesimal rings. ApJ, 985(1), 71. (www)

  @article{ , abstract = {In the standard planet formation scenario, planetesimals are assumed to form throughout the protoplanetary disk and to be smoothly distributed in the radial direction except for the snowline. Planetesimal growth has been investigated using this assumption, and the oligarchic growth model is widely accepted. However, recent simulations of gas and dust evolution have shown that planetesimals form only in radially limited locations, such as at gas pressure bumps and snowlines, and are concentrated in ring-like regions. When planetesimals are distributed in a ring-like region, scattered ones leak from the ring edge, resulting in planetesimal diffusion. To investigate protoplanet growth in expanding planetesimal rings, we perform a series of N -body simulations. In all the simulations, protoplanet growth is well explained by oligarchic growth, while the ring width expands due to planetesimal scattering by the protoplanets. Massive protoplanets tend to form near the ring center, and protoplanets that form far from the ring center are less massive than those in the center. The scaled orbital separations depend on neither the initial ring width nor the total mass, and they are consistent with estimates based on the oligarchic growth model and the diffused planetesimal distribution. The width of the expanded planetesimal ring does not depend on its initial width, but it does depend on its total mass. The maximum mass of protoplanets depends strongly on the total ring mass and weakly on the ring's initial width.}, archive = {J_ApJ}, author = {Yuki Kambara and Eiichiro Kokubo}, doi = {10.3847/1538-4357/adc999}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {71}, shortjournal = {The Astrophys. J.}, title = {Oligarchic growth of protoplanets in planetesimal rings}, volume = {985}, year = {2025}, }
• (2025). Mid-infrared ensemble variability of broad-line and narrow-line seyfert 1 galaxies. ApJ, 985(1), 70. (www)

  @article{ , abstract = {We utilized multiepoch archival data from the Wide-field Infrared Survey Explorer to compare the variability at 3.4 μ m (W1 band) and 4.6 μ m (W2 band) of broad-line Seyfert 1 (BLSy1) galaxies and narrow-line Seyfert 1 (NLSy1) galaxies by employing the ensemble structure function (SF). Additionally, we investigated the dependence of mid-infrared (MIR) ensemble SF on common active galactic nucleus parameters. The main results are as follows. (1) The ensemble SF of BLSy1 galaxies is larger than that of NLSy1 galaxies at long rest-frame time lags. (2) The ensemble SFs of BLSy1 galaxies, NLSy1 galaxies, and the combined sample are negatively correlated with the 5100 Å luminosity. The single power-law slope of the ensemble SF is proportional to luminosity. (3) The ensemble SFs of BLSy1 galaxies, NLSy1 galaxies, and the combined sample are negatively correlated with the Eddington ratio and the intensity of the Fe ii emission line. The MIR variability of the combined sample is positively correlated with black hole mass and the FWHM of the H β emission line at long rest-frame time lags. (4) The long-term MIR variability of the combined sample may be mainly driven by the Eddington ratio. (5) For BLSy1 galaxies, the MIR variability of radio-detected sources is greater than that of radio-undetected sources, whereas for NLSy1 galaxies, the opposite is true.}, archive = {J_ApJ}, author = {Zhipeng Hu and Lisheng Mao}, doi = {10.3847/1538-4357/adcabb}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {70}, shortjournal = {The Astrophys. J.}, title = {Mid-infrared ensemble variability of broad-line and narrow-line seyfert 1 galaxies}, volume = {985}, year = {2025}, }
• (2025). X-ray polarization variability during a few hz quasiperiodic oscillations in swift j1727.8-1613 observed with IXPE. ApJ, 985(1), 69. (www)

  @article{ , abstract = {We report the polarization properties of low-frequency quasiperiodic oscillations (LFQPOs) observed in Swift J1727.8−1613 with the Imaging X-ray Polarimetry Explorer (IXPE). LFQPOs have been observed in various objects, but their mechanisms remain unclear despite multiple proposed models. In order to understand the origin of the quasiperiodic oscillation mechanism, we investigated the short time variability of polarized X-rays. We analyzed three data sets of Swift J1727.8−1613, which were observed during the bright outburst and exhibited the LFQPO by IXPE. We employed a stacking analysis to understand the time variability of polarization during LFQPOs. We found evidence that the polarization degree is higher in the high-flux phase than in the low-flux phase. In addition, the polarization angle during the high-flux phase differed from that during the low-flux phase, although the trend was not entirely the same across the three observations. The variations in spectral hardness and polarization degree correlated with the intensity of LFQPO suggest geometrical changes in the Comptonization region or the involvement of complex Comptonization processes. X-ray polarization observation in wide band provides further understanding of the geometry and magnetic field structure of the accretion flows near the black hole.}, archive = {J_ApJ}, author = {Kaito Ninoyu and Shinya Yamada and Yuusuke Uchida and Taichi Igarashi and Ryota Hayakawa and Takayoshi Kohmura}, doi = {10.3847/1538-4357/adcabd}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {69}, shortjournal = {The Astrophys. J.}, title = {X-ray polarization variability during a few hz quasiperiodic oscillations in swift j1727.8-1613 observed with IXPE}, volume = {985}, year = {2025}, }
• (2025). A new hybrid machine learning method for stellar parameter inference. ApJ, 985(1), 68. (www)

  @article{ , abstract = {The advent of machine learning (ML) is revolutionary to numerous scientific disciplines, with a growing number of examples in astronomical spectroscopic inference, as ML is more powerful than traditional techniques. Here we introduce a hybrid ML (HML) method combining automatic differentiation, interpolation, and Bayesian optimization to infer stellar parameters of stellar spectra. We study T eff , {\mathrm{log}}\,(g) , and [Fe/H], but this method could be extended to other parameters such as [ α /Fe] (alpha element abundance), C/O (carbon–oxygen ratio), and f sed (sedimentation efficiency). We first use blase to semiempirically recast spectra into sets of Voigt profiles. blase is run on 1314 synthetic spectra from a rectilinear subset of the PHOENIX model grid ( T eff : [2300, 12,000] K, {\mathrm{log}}\,(g) : [2, 6], [Fe/H]: [–0.5, 0], λ : [8038, 12849] Å). For 128,723 detected features, we map stellar parameters to spectral line parameters using linear interpolation. This creates the PHOENIX generator, enabling parallelized spectral synthesis. Gaussian process minimization is used to infer stellar parameters by minimizing a rms loss function. Testing 210 noise-free models ( T eff : [3000, 11,000] K, {\mathrm{log}}\,(g) : [2, 6], [Fe/H]: [−0.5, 0]), we find inference errors: T eff : 93 K, {\mathrm{log}}\,(g) : 0.24, and [Fe/H]: 0.056 for T eff <  7000 K, and T eff : 347 K, {\mathrm{log}}\,(g) : 0.26, and [Fe/H]: 0.16 for T eff ≥ 7000 K. We also upload online an archive of blase models of the PHOENIX subset. This proof-of-concept study shows that semiempirical HML is a viable alternative to traditional approaches in spectroscopic inference.}, archive = {J_ApJ}, author = {Sujay Shankar and Michael A. Gully-Santiago and Caroline V. Morley}, doi = {10.3847/1538-4357/adcb47}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {68}, shortjournal = {The Astrophys. J.}, title = {A new hybrid machine learning method for stellar parameter inference}, volume = {985}, year = {2025}, }
• (2025). Characteristics of inertial range turbulent cascade rates in the interplanetary coronal mass ejection. ApJ, 985(1), 67. (www)

  @article{ , abstract = {Interplanetary coronal mass ejections (ICMEs) are different from the typical solar wind in their compressibility and levels of fluctuations in magnetic field, proton velocity, density, and temperature, making them a unique environment for studying turbulence properties. However, the difference between cascade rates in the ICMEs and typical solar wind, the comparison between cascade rates estimated by compressible and incompressible models, and how cascade rates in the ICMEs evolve with the radial distance from the Sun are still unclear. Using the data of 33 ICMEs observed between 0.305 au and 1.015 au by Parker Solar Probe and Solar Orbiter, we statistically investigated the incompressible and compressible inertial range turbulent cascade rates ( i and c ) in and around ICMEs. i and c in the sheaths and ejecta of ICMEs are always larger than in the upstream solar wind before them. i and c in the downstream solar wind behind ICMEs can be amplified after the ICMEs pass. c is always larger than i in all ICME subregions, indicating the amplifying effects of compressibility and levels of fluctuations in proton density, velocity, and temperature on the cascade rates of ICMEs. i and c in all ICME subregions decrease with the increase of the radial distance. These results shed light on our understanding of turbulent cascade rates and their radial evolution in ICMEs.}, archive = {J_ApJ}, author = {H. Bai and S. Y. Huang and J. Zhang and Z. G. Yuan and H. H. Wu and K. Jiang and Z. Wang and Q. Y. Xiong and R. T. Lin and Y. T. Tang}, doi = {10.3847/1538-4357/adcbae}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {67}, shortjournal = {The Astrophys. J.}, title = {Characteristics of inertial range turbulent cascade rates in the interplanetary coronal mass ejection}, volume = {985}, year = {2025}, }
• (2025). Modeling solar spectral irradiance from iron lines using the CODET model version 1.1. ApJ, 985(1), 66. (www)

  @article{ , abstract = {The COronal DEnsity and Temperature (CODET) model is a physics-based model. This model uses the relationship between the magnetic field, density, temperature, and extreme ultraviolet (EUV) emission. This model provides mean daily solar spectral irradiance (SSI) time series in EUV wavelengths in long timescales from days to solar cycles. The current manuscript presents the updated/new CODET model version 1.1. It uses observational data sets from the Solar Dynamics Observatory EUV Variability Experiment (SDO/EVE) MEGS-A at 28.4 and 21.1 nm wavelengths to obtain the goodness of fit between them and the modeled SSI from 2010 April 30 to 2014 May 26. The model described well observational data during that period, with less than 20% error in both wavelengths. Additionally, SSI predictions are provided using the new model parameters from 1996 July to 2024 October, where the Michelson Doppler Imager (MDI) and the Helioseismic and Magnetic Imager (HMI) photospheric magnetic field data are available. These predictions were compared with GOES/EUVS at 28.4 nm and mean daily values of the SDO Atmospheric Imaging Assembly at 21.1 nm data, with errors of ∼26% and 42% for 28.4 and 21.1 nm, respectively. The error analysis for model fitting and predictions shows how accurate the model predictions are. Thus, the CODET model provides a reliable estimate of the SSI time series in EUV wavelengths where no observational data are available, e.g., after the SDO/EVE MEGS-A era.}, archive = {J_ApJ}, author = {Jenny M. Rodríguez-Gómez}, doi = {10.3847/1538-4357/adcec6}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {66}, shortjournal = {The Astrophys. J.}, title = {Modeling solar spectral irradiance from iron lines using the CODET model version 1.1}, volume = {985}, year = {2025}, }
• (2025). Excitation of post-asymptotic giant branch star binary eccentricity by massive polar-aligned circumbinary disks. ApJ, 985(1), 65. (www)

  @article{ , abstract = {Many post-asymptotic giant branch star binaries are observed to have relatively high orbital eccentricities (up to 0.6). Recently, AC Her was observed to have a polar-aligned circumbinary disk. We perform hydrodynamic simulations to explore the impact of a polar-aligned disk on the eccentricity of a binary. For a binary system with central masses of 0.73 and 1.4 M ⊙ , we find that a disk with a total mass of 0.1 M ⊙ can enhance the binary eccentricity from 0.2 to 0.7 within 5000 yr, or from 0.01 to 0.65 within 15,000 yr. Even if the disk mass is as low as 0.01 M ⊙ , the binary eccentricity grows within our simulation time while the system remains stable. These eccentricity variations are associated with the variations of the inclination between the disk and the binary orbit due to von Zeipel–Kozai–Lidov oscillations. The oscillations eventually damp and leave the binary eccentricity at a high value. The numerical results are in good agreement with analytical estimates. In addition, we examine the AC Her system and find that the disk mass should be on the order of 10 −3 M ⊙ for the disk to remain polar.}, archive = {J_ApJ}, author = {Shunquan Huang and Rebecca G. Martin and Stephen H. Lubow}, doi = {10.3847/1538-4357/adcf1f}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {65}, shortjournal = {The Astrophys. J.}, title = {Excitation of post-asymptotic giant branch star binary eccentricity by massive polar-aligned circumbinary disks}, volume = {985}, year = {2025}, }
• (2025). Probing the he ii reionization ERA via absorbing c iv historical yield (HIERACHY). III. the c iv absorber catalog and initial results on cosmic abundance evolution at z ≈ 3–5. ApJ, 985(1), 64. (www)

  @article{ , abstract = {As part of the HIERACHY program, we collect the high signal-to-noise ratio and high-spectral resolution optical spectra of 25 quasars at z ≈ 4–5 to constrain the C iv evolution at z ≈ 3–5. In this paper, we report a catalog of 626 (1263) C iv absorption systems (components) at z ≈ 3–5 with a 50% completeness column density of log( N C iv /cm −2 ) ≈ 12.3. The HIERACHY/MIKE C iv sample is one of the best C iv absorber samples optimized to study the intergalactic medium during the He ii reionization epoch. Using 557 (1090) intervening absorption systems (components), we found the column density distribution function of C iv absorption systems with log( N C iv /cm −2 ) ≳ 12.3 has a broken power-law shape, with the turnover column density log ({N}_{\mathrm{crit}}/{\mathrm{cm}}^{-2})=13.3{5}_{-0.19}^{+0.20} , which is close to or smaller than the detection limit of most literature samples. We also found that both comoving path length number density dn / dX and cosmic abundance Ω for C iv absorption systems with log( N C iv /cm −2 ) > 13.2 show an increase (at the 2.2 σ and 1.4 σ levels, respectively) from redshift z ≈ 5–3, while absorption systems with log( N C iv /cm −2 ) = 12.3–13.2 exhibit a constant dn / dX and Ω C iv .}, archive = {J_ApJ}, author = {Xiaodi Yu and Zhijie Qu and Zheng Cai and Jiang-Tao Li and Huiyang Mao and Xin Wang}, doi = {10.3847/1538-4357/adc7ad}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {64}, shortjournal = {The Astrophys. J.}, title = {Probing the he ii reionization ERA via absorbing c iv historical yield (HIERACHY). III. the c iv absorber catalog and initial results on cosmic abundance evolution at z ≈ 3–5}, volume = {985}, year = {2025}, }
• (2025). Probing the he ii re-ionization ERa via absorbing c iv historical yield (HIERACHY). II. project design, current status, and examples of initial data products. ApJ, 985(1), 63. (www)

  @article{ , abstract = {The He ii reionization epoch is expected to take place at z ∼ 3–5. In this stage, the helium and metals in the intergalactic medium are further ionized with additional contributions from harder nonstellar sources, and some large-scale gravitationally bound systems approach virialization. The Probing the He ii re-Ionization ERa via Absorbing C iv Historical Yield (HIERACHY) program utilizes high- and medium-resolution spectra of bright background quasars at z ≈ 3.9–5.2 to investigate Ly α , C iv , and other metal absorption lines during this epoch. Additionally, we employ narrowband imaging to search for Ly α emitters associated with C iv absorbers, alongside multiwavelength observations to identify and study particularly intriguing cases. In this paper, we present the design of the HIERACHY program, its current status, major scientific goals, and examples of initial data products from completed Magellan/MIKE, MagE spectroscopy, and MDM imaging observations. We also provide a brief outlook on future multiwavelength observations that may significantly impact the related science.}, archive = {J_ApJ}, author = {Jiang-Tao Li and Xiaodi Yu and Huiyang Mao and Hanxiao Chen and Tiancheng Yang and Zhijie Qu and Fuyan Bian and Joel N. Bregman and Zheng Cai and Xiaohui Fan and Taotao Fang and Li Ji and Zhiyuan Ji and Sean D. Johnson and Guoliang Li and Weizhe Liu and Ying-Yi Song and Feige Wang and Tao Wang and Xin Wang and Christina Williams and Mingxuan Xu and Jinyi Yang and Yang Yang and Xianzhong Zheng}, doi = {10.3847/1538-4357/adc89d}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {63}, shortjournal = {The Astrophys. J.}, title = {Probing the he ii re-ionization ERa via absorbing c iv historical yield (HIERACHY). II. project design, current status, and examples of initial data products}, volume = {985}, year = {2025}, }
• (2025). Critical condition of core-collapse supernovae. i. one-dimensional models. ApJ, 985(1), 62. (www)

  @article{ , abstract = {When the core of a massive star collapses, neutrino heating can energize the stalled accretion shock, leading to a successful supernova. The critical condition that characterizes the transition from accretion to explosion is a central topic of study and is often characterized by a critical protoneutron star (PNS) neutrino luminosity {L}_{\nu }^{{\rm{crit}}} , which depends on the post-collapse mass-accretion rate \dot{M} from the progenitor. We examine the critical condition by solving the spherically symmetric time-dependent Euler equations with a general equation of state and realistic microphysics for a range of \dot{M} , average neutrino energy 〈 ν 〉, luminosity L ν , PNS radius R ⋆ , mass M ⋆ , and pre-shock Mach number { \mathcal M } for a fixed neutrino optical depth from the PNS surface of 2/3. We derive {L}_{\nu }^{{\rm{crit}}} as a function of the input parameters. We show that increasing the pressure of the pre-shock flow, as parameterized by lowering { \mathcal M } , lowers the normalization of the critical condition. We connect this finding with realistic massive progenitors and show that {L}_{\nu }^{{\rm{crit}}} can decrease by ∼5%–8% due to thermal changes during accretion of compositional interfaces onto the stalled shock. We test critical conditions that have been proposed in the literature, including the "antesonic" condition, the "force explosion condition," and the heuristic heating-advection timescale condition. We discuss how shock oscillations impact these critical conditions. Compared to other explosion conditions, we find that the antesonic ratio shows the least variation across the model space we explore. This work is preparatory for similar experiments in 2D axisymmetry and 3D.}, archive = {J_ApJ}, author = {David Pochik and Todd A. Thompson}, doi = {10.3847/1538-4357/adb57d}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {62}, shortjournal = {The Astrophys. J.}, title = {Critical condition of core-collapse supernovae. i. one-dimensional models}, volume = {985}, year = {2025}, }
• (2025). The HST-hyperion survey: Grism observations of a z ∼ 2.5 protosupercluster. ApJ, 985(1), 61. (www)

  @article{ , abstract = {We present the first results and catalogs from the HST-Hyperion survey. This survey has collected 50 orbits of WFC3/F160W imaging and WFC3/G141 grism spectroscopy in the most overdense regions of the Hyperion protosupercluster at z ∼ 2.45, which are analyzed in conjunction with the adjacent 56 orbits of WFC3/F140W imaging and WFC3/G141 grism spectroscopy from the 3D-HST survey. Sources were identified and spectra were extracted using grizli , which subsequently fit the combined grism data with object-matched photometric data from the COSMOS2020 catalog to obtain a redshift and best-fit spectral model. Each source was then visually inspected by multiple team members and quality flags were assigned. A total of 12,814 objects with m HST ≤ 25.0 were inspected, of which 5629 (44%) have reliable redshifts from the grism data and are sensitive to emission lines at a level of ∼8.8 × 10 −18 erg s −1 cm −2 (1 σ ). A comparison with high-quality, ground-based spectroscopic redshifts yields a scatter of σ NMAD = 0.0016. The resulting catalogs contain 125 confirmed members of the Hyperion structure within 2.40 < z < 2.53, with an additional 71 confirmed galaxies in projection within 2.35 < z < 2.65. The redshift, stellar population, and line flux catalogs, as well as all grism spectra, are publicly available.}, archive = {J_ApJ}, author = {Ben Forrest and Lu Shen and Brian C. Lemaux and Ekta Shah and Olga Cucciati and Roy R. Gal and Finn Giddings and Emmet Golden-Marx and Weida Hu and Kaila Ronayne and Derek Sikorski and Priti Staab and Ricardo O. Amorín and Sandro Bardelli and Bianca Garilli and Nimish Hathi and Denise Hung and Lori Lubin and Debora Pelliccia and Russell E. Ryan and Gianni Zamorani and Elena Zucca}, doi = {10.3847/1538-4357/adc252}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {61}, shortjournal = {The Astrophys. J.}, title = {The HST-hyperion survey: Grism observations of a z ∼ 2.5 protosupercluster}, volume = {985}, year = {2025}, }
• (2025). The local galactic transient survey applied to an optical search for directed intelligence. ApJ, 985(1), 60. (www)

  @article{ , abstract = {We discuss our transient search for directed energy systems in local galaxies, with calculations indicating the ability of modest searches to detect optical Search for Extraterrestrial Intelligence sources in the closest galaxies. Our analysis follows P. Lubin, where a messenger civilization follows a beacon strategy we call "intelligent targeting." We plot the required laser time to achieve a signal-to-noise ratio of 10 and find the time for a blind transmission to target all stars in the Milky Way to be achievable for local galactic civilizations. As high cadence and sky coverage is the pathway to enable such a detection, we operate the Local Galactic Transient Survey (LGTS) targeting M31 (the Andromeda galaxy), the Large Magellanic Cloud, and the Small Magellanic Cloud via Las Cumbres Observatory's network of 0.4 m telescopes. We explore the ability of modest searches like the LGTS to detect directed pulses in optical and near-infrared wavelengths from extraterrestrial intelligence at these distances, and conclude that a civilization utilizing less powerful laser technology than we can construct in this century is readily detectable with the LGTS's observational capabilities. Data processing of 30,000 LGTS images spanning 5 yr is in progress with the TRansient Image Processing Pipeline.}, archive = {J_ApJ}, author = {Alex Thomas and Natalie LeBaron and Luca Angeleri and Phillip Morgan and Varun Iyer and Prerana Kottapalli and Enda Mao and Samuel Whitebook and Jasper Webb and Dharv Patel and Rachel Darlinger and Kyle Lam and Kelvin Yip and Michael McDonald and Robby Odum and Cole Slenkovich and Yael Brynjegard-Bialik and Nicole Efstathiu and Joshua Perkins and Ryan Kuo and Audrey O’Malley and Alec Wang and Ben Fogiel and Sam Salters and Marlon Munoz and Natalie Kim and Lee Fowler and Ruiyang Wang and Philip Lubin}, doi = {10.3847/1538-4357/adc43d}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {60}, shortjournal = {The Astrophys. J.}, title = {The local galactic transient survey applied to an optical search for directed intelligence}, volume = {985}, year = {2025}, }
• (2025). PKS 2131−021—Discovery of strong coherent sinusoidal variations from radio to optical frequencies: Compelling evidence for a blazar supermassive black hole binary. ApJ, 985(1), 59. (www)

  @article{ , abstract = {Haystack and Owens Valley Radio Observatory observations recently revealed strong, intermittent, sinusoidal total flux-density variations that maintained their coherence between 1975 and 2021 in the blazar PKS 2131−021 ( z = 1.283). This was interpreted as possible evidence of a supermassive black hole binary (SMBHB). Extended observations through 2023 show a coherence over 47.9 yr, with an observed period P 15 GHz = (1739.8 ± 17.4) days. We reject, with p -value = 2.09 × 10 −7 , the hypothesis that the variations are due to random fluctuations in the red noise tail of the power spectral density. There is clearly a physical phenomenon in PKS 2131−021 producing coherent sinusoidal flux-density variations. We find the coherent sinusoidal intensity variations extend from below 2.7 GHz to optical frequencies, from which we derive an observed period P optical = (1764 ± 36) days. Across this broad frequency range, there is a smoothly varying monotonic phase shift in the sinusoidal variations with frequency. Hints of periodic variations are also observed at γ -ray energies. The importance of well-vetted SMBHB candidates to searches for gravitational waves is pointed out. We estimate the fraction of blazars that are SMBHB candidates to be >1 in 100. Thus, monitoring programs covering tens of thousands of blazars could discover hundreds of SMBHB candidates.}, archive = {J_ApJ}, author = {S. Kiehlmann and P. V. de la Parra and A. G. Sullivan and A. Synani and I. Liodakis and P. Mróz and S. K. Næss and A. C. S. Readhead and M. C. Begelman and R. D. Blandford and K. Chatziioannou and Y. Ding and M. J. Graham and F. Harrison and D. C. Homan and T. Hovatta and S. R. Kulkarni and M.L. Lister and R. Maiolino and W. Max-Moerbeck and B. Molina and C. P. O’Dea and V. Pavlidou and T. J. Pearson and M.F. Aller and C. R. Lawrence and T. J. W. Lazio and S. O’Neill and T. A. Prince and V. Ravi and R.A. Reeves and K. Tassis and M. Vallisneri and J. A. Zensus}, doi = {10.3847/1538-4357/adc567}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {59}, shortjournal = {The Astrophys. J.}, title = {PKS 2131−021—Discovery of strong coherent sinusoidal variations from radio to optical frequencies: Compelling evidence for a blazar supermassive black hole binary}, volume = {985}, year = {2025}, }
• (2025). Prediction of radio-quiet gamma-ray pulsar distances using the fundamental plane relation. ApJ, 985(1), 58. (www)

  @article{ , abstract = {The fundamental plane (FP) relation connects gamma-ray luminosity to intrinsic pulsar properties, offering the potential to estimate distances for radio-quiet (RQ) gamma-ray pulsars, where direct measurements are often unavailable. The Fermi Third Pulsar Catalog presents spectral data for 294 gamma-ray pulsars, including 72 RQ pulsars, of which only 9 have known distances. This study investigates the FP relation's potential to predict distances for RQ gamma-ray pulsars using machine learning (ML) approaches. Ordinary least-squares regression was employed alongside ML methods, including random forest and support vector regression, to predict RQ gamma-ray pulsar distances. To ensure robustness, the analysis considered spectral cutoff significance and outlier data. Results confirm that the FP relation is valid only for pulsars exhibiting significant gamma-ray cutoffs, with FP exponents closely matching theoretical expectations. It was shown that gamma-ray emission origins significantly favor the curvature radiation regime over the synchrotron regime at the 4.2 σ level. The distances for 62 RQ pulsars, for which no traditional measurements exist, are predicted for the first time. The luminosity and spatial distributions of the considered RQ pulsar population match known pulsar distributions. Predictions for RQ pulsars with known distances are consistent with measured data. This study provides a proof of principle that the FP relation, combined with ML methods, is a promising tool for distance estimation in RQ gamma-ray pulsars, using gamma-ray emission directly for the first time in pulsar distance estimates. Future improvements can be achieved with larger data sets, precise spectral cutoff determinations, and corrections for key factors like the beaming factor.}, archive = {J_ApJ}, author = {Ekrem Oğuzhan Angüner}, doi = {10.3847/1538-4357/adc914}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {58}, shortjournal = {The Astrophys. J.}, title = {Prediction of radio-quiet gamma-ray pulsar distances using the fundamental plane relation}, volume = {985}, year = {2025}, }
• (2025). Radio emission across the entire rotation phases of pulsars. ApJ, 985(1), 57. (www)

  @article{ , abstract = {Supersensitive observations of bright pulsars by the Five-hundred-meter Aperture Spherical Telescope have revealed weak radio emission continuously emerges in the rotation phases between the "main" pulse and "interpulse" of a rotating neutron star. We develop a model for the polarized radio emission radiated from different heights in the pulsar magnetosphere, and examine the emission intensity distribution over the whole rotation phases of pulsars seen from all directions by the line of sight. We find that for pulsars with small periods and a magnetosphere filled with much more relativistic particles, the polarized radio emission can be generated in all rotation phases for both the aligned and perpendicular rotating neutron stars. When the line of sight cuts the pulsar emission beam between the rotation and magnetic axes, the polarization angles have the same sense of variation gradient for the main pulse and interpulse. If the line of sight cuts the beams between the inclined magnetic axis and the equator, the opposite senses can be found for the main pulse and interpulse. In addition to the pulsed emission, we find persistent radio emission generated in the pulsar magnetosphere. The model can naturally explain the emission across the entire rotation phases.}, archive = {J_ApJ}, author = {P. F. Wang and J. L. Han}, doi = {10.3847/1538-4357/adc9a6}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {57}, shortjournal = {The Astrophys. J.}, title = {Radio emission across the entire rotation phases of pulsars}, volume = {985}, year = {2025}, }
• (2025). Effects of waves on the spectral anisotropy of the transition range in solar wind turbulence. ApJ, 985(1), 56. (www)

  @article{ , abstract = {In the transition range of the solar wind turbulence, the magnetic spectrum has been observed to be strongly anisotropic with respect to the local mean field. However, the generation mechanism of the anisotropy remains not well understood. There are two typical types of waves existing in the transition range, including ion cyclotron waves (ICWs) and kinetic Alfvén waves (KAWs) propagating in the directions parallel and perpendicular to the magnetic field, respectively. In this work, we perform a statistical study about the effects of the waves on the spectral anisotropy of the transition range. We select 31 intervals from the measurements of Parker Solar Probe between 2018 and 2021. The magnetic helicity ( σ m ) diagnosis is applied on the magnetic field data, and the wavelet coefficients with σ m ≤ −0.5 and σ m ≥ 0.4 are considered as signals of ICWs and KAWs, respectively. For the first time, we remove both ICWs and KAWs systematically from the power spectral density of magnetic field fluctuations and find that the magnetic spectral anisotropy in the transition range becomes significantly weaker. Specifically, the spectra in the quasi-parallel direction statistically get shallower, and the average spectral index changes from −5.68 ± 0.74 to −4.72 ± 0.56. By contrast, the spectra in the perpendicular direction get slightly steeper, and the index changes from −3.63 ± 0.34 to −3.95 ± 0.41. Moreover, the anisotropic scaling in the transition range is found to be {k}_{\parallel }\sim {k}_{\perp }^{1.53\pm 0.33} . The new results will help to further understand the possible mechanisms that cause the spectral anisotropy in the transition range.}, archive = {J_ApJ}, author = {Hua Zhang and Xin Wang and Haochen Yuan}, doi = {10.3847/1538-4357/adc9a8}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {56}, shortjournal = {The Astrophys. J.}, title = {Effects of waves on the spectral anisotropy of the transition range in solar wind turbulence}, volume = {985}, year = {2025}, }
• (2025). Dust battery: A novel mechanism for seed magnetic field generation in the early universe. ApJ, 985(1), 55. (www)

  @article{ , abstract = {We propose a novel dust battery mechanism for generating seed magnetic fields in the early Universe, in which charged dust grains are radiatively accelerated, inducing strong electric currents that subsequently generate magnetic fields. Our analysis demonstrates that this process is effective even at very low metallicities (approximately ∼10 −5 Z ⊙ ), and capable of producing seed fields with significant amplitudes of B ∼ μ G around luminous sources over timescales of years to Myr and across spatial scales ranging from au to kpc. Crucially, we find that this mechanism is generically ∼10 8 times more effective than the radiatively driven electron battery or Biermann battery in relatively cool gas (≪10 5 K), including both neutral and ionized gas. Furthermore, our results suggest that, to first order, dissipation effects do not appear to significantly impede this process, and that it can feasibly generate coherent seed fields on macroscopically large interstellar medium (ISM) scales (much larger than turbulent dissipation scales or electron mean-free-paths in the ISM). These seed fields could then be amplified by subsequent dynamo actions to the observed magnetic fields in galaxies. Additionally, we propose a subgrid model for integration into cosmological simulations, and the required electric-field expressions for magnetohydrodynamic-particle-in-a-cell simulations that explicitly model dust dynamics. Finally, we explore the broad applicability of this mechanism across different scales and conditions, emphasizing its robustness compared to other known battery mechanisms.}, archive = {J_ApJ}, author = {Nadine H. Soliman and Philip F. Hopkins and Jonathan Squire}, doi = {10.3847/1538-4357/adcb39}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {55}, shortjournal = {The Astrophys. J.}, title = {Dust battery: A novel mechanism for seed magnetic field generation in the early universe}, volume = {985}, year = {2025}, }
• (2025). Predicting the solar wind speed and interplanetary sector structure during solar cycles 21–25. ApJ, 985(1), 54. (www)

  @article{ , abstract = {We use potential-field source-surface (PFSS) extrapolations of photospheric field data to predict the solar wind speed and interplanetary sector structure at Earth during solar cycles 21–25, and compare the results with in situ measurements. The wind speed is taken to be inversely correlated with the rate of coronal flux-tube expansion, which is derived using photospheric synoptic maps from the Wilcox Solar Observatory, the National Solar Observatory, the Global Oscillation Network Group, and the Helioseismic and Magnetic Imager. The extrapolations tend to predict too much fast wind near sunspot minimum, when the heliospheric current sheet is located near the ecliptic and the latitudinal gradients in the wind speed are very steep; the predictions are generally best during the declining phase of each cycle (with correlation coefficients of order 0.35–0.5), when large low-latitude extensions of the polar coronal holes give rise to recurrent high-speed streams. The overprediction of fast wind during 2009 and 2019 is associated with an overestimate of the areal sizes of remnant coronal holes and of the warping of the streamer belt. These in turn may be caused by an underestimate of the Sun's axial dipole or polar field strength and by the omission of the effect of the low-latitude sheet currents beyond 2.5 R ⊙ on the near-coronal field. The latter currents act to decrease the sizes of open field regions relative to the PFSS model, with the result being similar to that of moving the source surface outward from 2.5 to 3.0 R ⊙ .}, archive = {J_ApJ}, author = {Y.-M. Wang and N. R. Sheeley}, doi = {10.3847/1538-4357/adcbaa}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {54}, shortjournal = {The Astrophys. J.}, title = {Predicting the solar wind speed and interplanetary sector structure during solar cycles 21–25}, volume = {985}, year = {2025}, }
• (2025). Artificial intelligence for the characterization of the 2024 may superstorm: Active region classification, flare forecasting, and geomagnetic storm prediction. ApJ, 985(1), 53. (www)

  @article{ , abstract = {Space weather, driven by solar flares and coronal mass ejections, poses significant risks to technological systems. Accurately forecasting these events and their impact on Earth's magnetosphere remains a challenge because of the complexity of solar–terrestrial interactions. This study focuses on the solar and geomagnetic extreme events associated with the 2024 May superstorm and shows that artificial intelligence (AI) tools are able to characterize this storm at three different levels. First, using magnetogram cutouts, a vision transformer was able to classify the morphological evolution of NOAA Active Region 13644 (primarily involved in storm generation), and then a video-based deep learning method predicted the occurrence of the associated solar flares, and a data-driven method exploited in situ measurements to raise 1-hour in advance alerts of the geomagnetic storm during the entire event. These AI models outperformed traditional methods in predicting solar flare occurrences, onset, and recovery phases of the geomagnetic storm. These findings highlight the impressive potential of AI for space weather forecasting as a tool to mitigate the impact of extreme solar events on critical infrastructure.}, archive = {J_ApJ}, author = {Sabrina Guastavino and Edoardo Legnaro and Anna Maria Massone and Michele Piana}, doi = {10.3847/1538-4357/adcd62}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {53}, shortjournal = {The Astrophys. J.}, title = {Artificial intelligence for the characterization of the 2024 may superstorm: Active region classification, flare forecasting, and geomagnetic storm prediction}, volume = {985}, year = {2025}, }
• (2025). Two distinctly different characteristics of flare-driven coronal rain revealed from high-resolution spectroscopic imaging observations with FISS/GST. ApJ, 985(1), 52. (www)

  @article{ , abstract = {We report on a flare-driven coronal rain event observed along postflare loops during the decay phase of an X1.6-class solar flare. Although high-resolution studies of flare-driven coronal rain have been conducted, imaging spectroscopic studies are rare due to observational difficulties. Our observation taken with the Fast Imaging Solar Spectrograph, installed at the 1.6 m Goode Solar Telescope of the Big Bear Solar Observatory, provided unprecedented high-resolution spectroscopic imaging data of coronal rain in the H α and Ca ii 854.2 nm lines. We identify two locations along postflare loops with rain displaying distinctly different thermal properties, different Doppler velocities, and different patterns of acceleration and deceleration. We also observed intense brightening at one footpoint of coronal rain, where the spectroscopic analysis reveals an energy conversion process resulting in significant localized chromospheric heating. We thoroughly investigate the footpoint brightening Doppler velocities and compare their spectral line profiles to typical flare-ribbon line profiles. We estimate the spatial scale of the fine structure of the coronal rain and the footpoint brightening. Our results provide important insights into the dynamic and thermal properties of flare-driven coronal rain and the related chromospheric response, which will help validate the flare-driven modeling of coronal rain.}, archive = {J_ApJ}, author = {Donguk Song and Eun-Kyung Lim and Jongchul Chae and Maria S. Madjarska and Masahito Kubo and Hannah Kwak and Juhyung Kang and Ryohtaroh T. Ishikawa and Kyoung-Sun Lee}, doi = {10.3847/1538-4357/adcf25}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {52}, shortjournal = {The Astrophys. J.}, title = {Two distinctly different characteristics of flare-driven coronal rain revealed from high-resolution spectroscopic imaging observations with FISS/GST}, volume = {985}, year = {2025}, }
• (2025). Dinosaur in a haystack: X-ray view of the entrails of SN 2023ixf and the radio afterglow of its interaction with the medium spawned by the progenitor star (Paper i)*. ApJ, 985(1), 51. (www)

  @article{ , abstract = {We present the results from our extensive hard-to-soft X-ray (NuSTAR, Swift-XRT, XMM-Newton, Chandra) and meter-to-millimeter-wave radio (Giant Metrewave Radio Telescope, Very Large Array, NOEMA) monitoring campaign of the very nearby ( d = 6.9 Mpc) Type II supernova (SN) 2023ixf spanning ≈4–165 days post-explosion. This unprecedented data set enables inferences on the explosion's circumstellar medium (CSM) density and geometry. In particular, we find that the luminous X-ray emission is well modeled by thermal free–free radiation from the forward shock with rapidly decreasing photoelectric absorption with time. The radio spectrum is dominated by synchrotron radiation from the same shock. Similar to the X-rays, the level of free–free absorption affecting the radio spectrum rapidly decreases with time as a consequence of the shock propagation into the dense CSM. While the X-ray and the radio modeling independently support the presence of a dense medium corresponding to an effective mass-loss rate \dot{M}\approx 1{0}^{-4}\,{M}_{\odot }\,{\mathrm{yr}}^{-1} at R = (0.4–14) × 10 15 cm (for v w = 25 km s −1 ), our study points at a complex CSM density structure with asymmetries and clumps. The inferred densities are ≈10–100 times those of typical red supergiants, indicating an extreme mass-loss phase of the progenitor in the ≈200 yr preceding core collapse, which leads to the most X-ray luminous Type II SN and the one with the most delayed emergence of radio emission. These results add to the picture of the complex mass-loss history of massive stars on the verge of collapse and demonstrate the need for panchromatic campaigns to fully map their intricate environments.}, archive = {J_ApJ}, author = {Nayana A. J. and Raffaella Margutti and Eli Wiston and Ryan Chornock and Sergio Campana and Tanmoy Laskar and Kohta Murase and Melanie Krips and Giulia Migliori and Daichi Tsuna and Kate D. Alexander and Poonam Chandra and Michael Bietenholz and Edo Berger and Roger A. Chevalier and Fabio De Colle and Luc Dessart and Rebecca Diesing and Brian W. Grefenstette and Wynn V. Jacobson-Galán and Keiichi Maeda and Benito Marcote and Daisy Matthews and Dan Milisavljevic and Alak K. Ray and Andrea Reguitti and Ava Polzin}, doi = {10.3847/1538-4357/adc2fb}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {51}, shortjournal = {The Astrophys. J.}, title = {Dinosaur in a haystack: X-ray view of the entrails of SN 2023ixf and the radio afterglow of its interaction with the medium spawned by the progenitor star (Paper i)*}, volume = {985}, year = {2025}, }
• (2025). Deep Mantle–Atmosphere coupling and carbonaceous bombardment: Options for biomolecule formation on an oxidized early earth. ApJ, 985(1), 50. (www)

  @article{ , abstract = {Understanding what environmental conditions prevailed on early Earth during the Hadean eon, and how this set the stage for the origins of life, remains a challenge. Geologic processes such as serpentinization and bombardment by chondritic material during the late veneer might have been very active, shaping an atmospheric composition reducing enough to allow efficient photochemical synthesis of HCN, one of the key precursors of prebiotic molecules. HCN can rain out and accumulate in warm little ponds (WLPs), forming prebiotic molecules such as nucleobases and the sugar ribose. These molecules could condense to nucleotides, the building blocks of RNA molecules, one of the ingredients of life. Here, we perform a systematic study of potential sources of reducing gases on Hadean Earth and calculate the concentrations of prebiotic molecules in WLPs based on a comprehensive geophysical and atmospheric model. We find that in a reduced H 2 -dominated atmosphere, carbonaceous bombardment can produce enough HCN to reach maximum WLP concentrations of  ∼1–10 mM for nucleobases and, in the absence of seepage,  ∼10–100 μ M for ribose. If the Hadean atmosphere was initially oxidized and CO 2 -rich (90%), we find serpentinization alone can reduce the atmosphere, resulting in WLP concentrations of an order of magnitude lower than the reducing carbonaceous bombardment case. In both cases, concentrations are sufficient for nucleotide synthesis, as shown in experimental studies. RNA could have appeared on Earth immediately after it became habitable (about 100 Myr after the Moon-forming impact), or it could have (re)appeared later at any time up to the beginning of the Archean.}, archive = {J_ApJ}, author = {Klaus Paschek and Thomas K. Henning and Karan Molaverdikhani and Yoshinori Miyazaki and Ben K. D. Pearce and Ralph E. Pudritz and Dmitry A. Semenov}, doi = {10.3847/1538-4357/adc39b}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {50}, shortjournal = {The Astrophys. J.}, title = {Deep Mantle–Atmosphere coupling and carbonaceous bombardment: Options for biomolecule formation on an oxidized early earth}, volume = {985}, year = {2025}, }
• (2025). Nonlinear interactions in spherically polarized alfvénic turbulence. ApJ, 985(1), 49. (www)

  @article{ , abstract = {Turbulent magnetic field fluctuations observed in the solar wind often maintain a constant-magnitude magnetic field accompanied by spherically polarized velocity fluctuations; these signatures are characteristic of large-amplitude Alfvén waves. Nonlinear energy transfer in Alfvénic turbulence is typically considered in the small-amplitude limit where the constant-magnitude condition may be neglected; in contrast, nonlinear energy transfer of large-amplitude fluctuations remains relatively unstudied. We develop a method to analyze large-amplitude turbulence through studying fluctuations as constant-magnitude rotations in the de Hoffmann–Teller frame, in which the convected electric field of the fluctuations vanishes such that the frame and fluctuations are copropagating. Our analysis reveals signatures of large-amplitude effects deep into the inertial range. While the dominant fluctuations are consistent with spherically polarized large-amplitude Alfvén waves, the subdominant fluctuations are relatively compressible. Signatures of nonlinear interaction between the large-amplitude spherically polarized mode with the subdominant population reveal highly aligned transverse components. In many theoretical models of Alfvénic turbulence, alignment is thought to reduce nonlinearity; our observations suggest that the observed alignment is sufficient to either reduce shear nonlinearity such that non-Alfvénic interactions may be responsible for energy transfer in spherically polarized states, or alternatively that counterpropagating fluctuations maintain anomalous coherence, a predicted signature of reflection-driven turbulence.}, archive = {J_ApJ}, author = {Trevor A. Bowen and Corina I. Dunn and Alfred Mallet and Jonathan Squire and Samuel T. Badman and Stuart D. Bale and Thierry Dudok de Wit and Timothy S. Horbury and Kristopher G. Klein and Davin Larson and Lorenzo Matteini and Michael D. McManus and Nikos Sioulas}, doi = {10.3847/1538-4357/adc569}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {49}, shortjournal = {The Astrophys. J.}, title = {Nonlinear interactions in spherically polarized alfvénic turbulence}, volume = {985}, year = {2025}, }
• (2025). Simulating solar neighborhood brown dwarfs. i. the luminosity function above and below the galactic plane. ApJ, 985(1), 48. (www)

  @article{ , abstract = {Brown dwarfs form the key, yet poorly understood, link between stellar and planetary astrophysics. These objects offer unique tests of Galactic structure, but observational limitations have inhibited their large-scale analysis to date. Major upcoming sky surveys will reveal unprecedented numbers of brown dwarfs, among even greater numbers of stellar objects, greatly enhancing the statistical study of brown dwarfs. To extract the comparatively rare brown dwarfs from these massive data sets, we must understand the parameter space they will occupy. In this work, we construct synthetic populations of brown dwarfs in the solar neighborhood to explore their evolutionary properties using Gaia-derived star formation histories alongside observational mass, metallicity, and age relationships. We apply the Sonora Bobcat, Saumon−Marley, and Sonora Diamondback evolutionary models. From the populations, we explore the space densities and median ages by spectral type. We present the simulated luminosity function and its evolution with distance from the Galactic plane. Our simulation shows that brown dwarf population statistics are a function of height above/below the Galactic plane and sample different age distributions. Interpreting the local sample requires combining evolutionary models, the initial mass function, the star formation history, and kinematic heating. Our models are a guide to how well height-dependent samples can test these scenarios. Subpopulations of brown dwarfs farther from the Galactic plane are older and occupy a different region of parameter space than younger subpopulations closer to the Galactic plane. Therefore, fully exploring population statistics both near and far from the Galactic plane is critical to prepare for upcoming surveys.}, archive = {J_ApJ}, author = {Easton J. Honaker and John E. Gizis}, doi = {10.3847/1538-4357/adc689}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {48}, shortjournal = {The Astrophys. J.}, title = {Simulating solar neighborhood brown dwarfs. i. the luminosity function above and below the galactic plane}, volume = {985}, year = {2025}, }
• (2025). Investigation of substructures of the inner halo using the StarGO algorithm with APOGEE DR17. ApJ, 985(1), 47. (www)

  @article{ , abstract = {We applied the Stars' Galactic Origin algorithm in 7D space (i.e., [Fe/H], [Mg/Fe], [Al/Fe], L z , J r , J z , E ) to analyze stars in the inner halo with APOGEE DR17. We identified some known substructures, including Gaia-Sausage/Enceladus, Sagittarius stream (Sgr), LMS-1 (Wukong), Thamnos, the metal-weak thick disk, and Aleph. Additionally, we identified an undefined metal-poor group (UDG, with [Fe/H] < −0.8 dex) probably linked to a known substructure like Aleph, as well as a high α -abundance substructure (HAS) associated with both the Nyx and Nyx-2 streams. Chemical abundance of the HAS supports the argument that Nyx and Nyx-2 share a common origin. We discovered three substructures, which we refer to as new substructure candidates 1, 2, and 3 (NSTC-1, NSTC-2, NSTC-3). Despite exhibiting disk-like dynamics, these NSTCs demonstrate notably low [Mg/Fe] (<0.2 dex) and [Al/Fe] (<−0.15 dex), similar to the properties of dwarf galaxies. Their high orbital energy and low [ α /Fe] indicate the association with recent accretion events.}, archive = {J_ApJ}, author = {Zhongcheng Li and Cuihua Du and Haoyang Liu and Dashuang Ye}, doi = {10.3847/1538-4357/adc809}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {47}, shortjournal = {The Astrophys. J.}, title = {Investigation of substructures of the inner halo using the StarGO algorithm with APOGEE DR17}, volume = {985}, year = {2025}, }
• (2025). Variations in the magnetic field strength of pre-main-sequence stars, solar-type main-sequence stars, and the sun. ApJ, 985(1), 46. (www)

  @article{ , abstract = {The surface magnetic fields of pre-main-sequence stars and zero-age main-sequence stars are notably strong, resulting in the generation of numerous spots and the emission of bright chromospheric lines. Rotational variations in magnetic field strength have been identified in T Tauri stars (TTSs) and young main-sequence stars using Zeeman–Doppler imaging. This study investigates the relationship between the mean values and variation amplitudes of the magnetic field strengths of TTSs, main-sequence stars, and the Sun. The findings reveal a positive correlation of over 3 orders of magnitude, suggesting that a common mechanism drives the magnetic fields of these stars. This positive correlation implies that stars with larger spot sizes experience greater variation amplitudes due to rotational modulations. For the Sun, both the mean magnetic field strength value and its variation amplitude tend to be higher during solar maximum than during solar minimum.}, archive = {J_ApJ}, author = {Mai Yamashita and Yoichi Itoh and Shin Toriumi}, doi = {10.3847/1538-4357/adc816}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {46}, shortjournal = {The Astrophys. J.}, title = {Variations in the magnetic field strength of pre-main-sequence stars, solar-type main-sequence stars, and the sun}, volume = {985}, year = {2025}, }
• (2025). Investigating the recursive short X-ray burst behavior of magnetars through crustal interactions. ApJ, 985(1), 45. (www)

  @article{ , abstract = {Energetic bursts from strongly magnetized neutron stars, known as magnetars, are typically detected in clusters. Once an active episode begins, anywhere from a few to thousands of hard X-ray bursts can occur over durations ranging from days to months. The temporal clustering of these recurrent bursts during an active episode suggests an underlying mechanism that triggers multiple bursts in rapid succession. These burst clusters are likely crucial for understanding the processes driving magnetar activity. In this study, we investigate the repetitive short X-ray burst behavior of magnetars through crustal interactions, employing the cellular automaton model for the magnetar crust proposed by S. K. Lander. Our simulations, based on physically motivated criteria, successfully reproduce burst clustering. Additionally, the durations and energetics of active episodes in our simulations agree well with observational data. We discuss the potential physical mechanisms underlying burst clusters observed in numerous magnetars, as well as the reactivations of an individual magnetar.}, archive = {J_ApJ}, author = {Özge Keskin and Samuel K. Lander and Ersin Göğüş}, doi = {10.3847/1538-4357/adc915}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {45}, shortjournal = {The Astrophys. J.}, title = {Investigating the recursive short X-ray burst behavior of magnetars through crustal interactions}, volume = {985}, year = {2025}, }
• (2025). MUSEQuBES: The column density, covering fraction, and mass of o vi-bearing gas in and around low-redshift galaxies. ApJ, 985(1), 44. (www)

  @article{ , abstract = {We present a study of O vi -bearing gas around 247 low-mass (median {\mathrm{log}}_{10}({M}_{\star }/{M}_{\odot }) = 8.7) galaxies at low redshifts (0.1 < z < 0.7) using background quasars as part of the MUSE Quasar-fields Blind Emitters Survey (MUSEQuBES). We find that the average O vi column density, {{\rm{log}}}_{10}\left\langle N({\rm{O}}\,{\rm\small{VI}})/{{\rm{cm}}}^{-2}\right\rangle =14.1{4}_{-0.10}^{+0.09} , measured within the virial radius for our sample, is significantly lower than for L * galaxies. Combining 253 star-forming galaxies (mostly more massive) from the literature with 176 star-forming galaxies from MUSEQuBES, we find that both \left\langle N({\rm{O}}\,{\rm\small{VI}})\right\rangle and the average covering fraction peak at {\mathrm{log}}_{10}({M}_{\star }/{M}_{\odot }) ≈ 9.5. The virial temperature corresponding to this stellar mass is ideal for O vi production via collisional ionization. However, we argue that photoionization and/or nonequilibrium processes are necessary to produce the O vi associated with low-mass, dwarf galaxies ( {\mathrm{log}}_{10}({M}_{\star }/{M}_{\odot }) < 9). The average O vi mass within the virial radius of dwarf galaxies is measured to be 1{0}^{5.{2}_{-0.1}^{+0.1}} M ⊙ . The characteristic normalized impact parameter ( D / R vir ) at which the O vi covering fraction drops to half of its peak value is largest (≈1.1) for galaxies with stellar mass {\mathrm{log}}_{10}({M}_{\star }/{M}_{\odot }) ≈ 9.5. We report the presence of a highly ionized metal floor with {\mathrm{log}}_{10}N({\rm{O}}\,{\rm\small{VI}})/{{\rm{cm}}}^{-2}=13.2 outside the virial radius of dwarf galaxies inferred from median spectral stacking.}, archive = {J_ApJ}, author = {Sayak Dutta and Sowgat Muzahid and Joop Schaye and Nicolas F. Bouché and Sebastiano Cantalupo and Hsiao-Wen Chen and Sean Johnson}, doi = {10.3847/1538-4357/adc922}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {44}, shortjournal = {The Astrophys. J.}, title = {MUSEQuBES: The column density, covering fraction, and mass of o vi-bearing gas in and around low-redshift galaxies}, volume = {985}, year = {2025}, }
• (2025). Basic pattern of three-dimensional magnetic reconnection within strongly turbulent current sheets. ApJ, 985(1), 43. (www)

  @article{ , abstract = {Magnetic reconnection is a fundamental mechanism of driving eruptive phenomena of different scales and may be coupled with turbulence as suggested by recent remote-sensing and in situ observations. However, the specific physics behind the complex three-dimensional (3D) turbulent reconnection remains mysterious. Here, we develop a novel methodology to identify and analyze multitudes of multiscale reconnection fragments within a strongly turbulent current sheet (CS) and apply it to a state-of-the-art numerical simulation of turbulent reconnection for solar flares. It is determined that the reconnection fragments tend to appear as quasi-2D sheets forming along local magnetic flux surfaces, and, due to strong turbulence, their reconnection flow velocities and reconnection rates are significantly broadened statistically but are scale independent. Each reconnection fragment is found to be surrounded by strongly fluctuated in/outflows and has a widely distributed reconnection rate, mainly in the range of 0.01–0.1. The results, for the first time, provide quantitative measurements of 3D magnetic reconnection in strongly turbulent flare CSs, offering insights into the cascading laws of 3D reconnection in other turbulent plasmas.}, archive = {J_ApJ}, author = {Yulei Wang and Xin Cheng and Mingde Ding}, doi = {10.3847/1538-4357/adca3d}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {43}, shortjournal = {The Astrophys. J.}, title = {Basic pattern of three-dimensional magnetic reconnection within strongly turbulent current sheets}, volume = {985}, year = {2025}, }
• (2025). How to identify the object with a mass range of (2.2–3) m⊙ in the merger of compact star systems. ApJ, 985(1), 42. (www)

  @article{ , abstract = {High-frequency gravitational-wave (GW) radiation has been detected by LIGO-Virgo-KAGRA in the merger of compact stars. However, in two GW events, GW190814 and GW200210, the mass of one companion object falls into the mass region of (2.2–3) M ⊙ , and how to identify such an object (e.g., as a low-mass black hole (BH) or a massive neutron star (NS)) remains an open question. In this paper, we propose a method to identify the mystery compact object (MCO) with the mass region of (2.2–3) M ⊙ in a binary system via the possible electromagnetic (EM) radiations before and after the mergers. A multiband EM emission can be produced with L ∝ ( − t ) 7/4 (or L ∝ ( − t ) −5/4 ) during the inspiral phase due to the BH battery (or interaction magnetospheres) mechanism, and a bright (or dark) kilonova emission is powered by radioactive decay with ejecta mass ratio q > 1.7 (or q < 1.7) during the postmerge state when MCO is as a low-mass BH (or massive NS) to merger with NS. Moreover, by considering the merger system between MCO and a BH when MCO is a massive NS, we find that it requires the BH with high spin (e.g., a ∼ 0.8–0.99) to make sure the tidal disruption event occurred, and a multiband precursor emission and bright kilonova emission can also be produced during the inspiral phase and postmerge state, respectively. In any case, no matter which mechanism we adopt, such precursor emissions are too weak to be detected by most current telescopes unless the distance is close enough.}, archive = {J_ApJ}, author = {Zhao-Wei Du and HouJun Lü and Xiaoxuan Liu and XiLong Fan and EnWei Liang}, doi = {10.3847/1538-4357/adcb49}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {42}, shortjournal = {The Astrophys. J.}, title = {How to identify the object with a mass range of (2.2–3) m⊙ in the merger of compact star systems}, volume = {985}, year = {2025}, }
• (2025). Accessing a new population of supermassive black holes with extensions to the event horizon telescope. ApJ, 985(1), 41. (www)

  @article{ , abstract = {The Event Horizon Telescope (EHT) has produced resolved images of the supermassive black holes (SMBHs) Sgr A* and M87*, which present the largest shadows on the sky. In the next decade, technological improvements and extensions to the array will enable access to a greater number of sources, unlocking studies of a larger population of SMBHs through direct imaging. In this paper, we identify 12 of the most promising sources beyond Sgr A* and M87* based on their angular size and millimeter flux density. For each of these sources, we make theoretical predictions for their observable properties by ray tracing general relativistic magnetohydrodynamic models appropriately scaled to each target's mass, distance, and flux density. We predict that these sources would have somewhat higher Eddington ratios than M87*, which may result in larger optical and Faraday depths than previous EHT targets. Despite this, we find that visibility amplitude size constraints can plausibly recover masses within a factor of 2, although the unknown jet contribution remains a significant uncertainty. We find that the linearly polarized structure evolves substantially with the Eddington ratio, with greater evolution at larger inclinations, complicating potential spin inferences for inclined sources. We discuss the importance of 345 GHz observations, milli-Jansky baseline sensitivity, and independent inclination constraints for future observations with upgrades to the EHT through ground updates with the next-generation EHT program and extensions to space through the black hole Explorer.}, archive = {J_ApJ}, author = {Xinyue Alice Zhang and Angelo Ricarte and Dominic W. Pesce and Michael D. Johnson and Neil Nagar and Ramesh Narayan and Venkatessh Ramakrishnan and Sheperd Doeleman and Daniel C. M. Palumbo}, doi = {10.3847/1538-4357/adbd45}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {41}, shortjournal = {The Astrophys. J.}, title = {Accessing a new population of supermassive black holes with extensions to the event horizon telescope}, volume = {985}, year = {2025}, }
• (2025). Mahakala: A python-based modular ray-tracing and radiative transfer algorithm for curved spacetimes. ApJ, 985(1), 40. (www)

  @article{ , abstract = {We introduce Mahakala , a Python -based, modular, radiative ray-tracing code for curved spacetimes. We employ Google's JAX framework for accelerated automatic differentiation, which can efficiently compute Christoffel symbols directly from the metric, allowing the user to easily and quickly simulate photon trajectories through non-Kerr spacetimes. JAX also enables Mahakala to run in parallel on both CPUs and GPUs. Mahakala natively uses the Cartesian Kerr–Schild coordinate system, which avoids numerical issues caused by the pole in spherical coordinate systems. We demonstrate Mahakala 's capabilities by simulating 1.3 mm wavelength images (the wavelength of Event Horizon Telescope observations) of general relativistic magnetohydrodynamic simulations of low-accretion rate supermassive black holes. The modular nature of Mahakala allows us to quantitatively explore how different regions of the flow influence different image features. We show that most of the emission seen in 1.3 mm images originates close to the black hole and peaks near the photon orbit. We also quantify the relative contribution of the disk, forward jet, and counterjet to 1.3 mm images.}, archive = {J_ApJ}, author = {Aniket Sharma and Lia Medeiros and George N. Wong and Chi-kwan Chan and Goni Halevi and Patrick D. Mullen and James M. Stone}, doi = {10.3847/1538-4357/adc104}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {40}, shortjournal = {The Astrophys. J.}, title = {Mahakala: A python-based modular ray-tracing and radiative transfer algorithm for curved spacetimes}, volume = {985}, year = {2025}, }
• (2025). Multiwavelength long-term studies of radio galaxy NGC 1275. ApJ, 985(1), 39. (www)

  @article{ , abstract = {It is widely considered that the processes of an interaction between the energy and radiation, which are generated in the active galactic nuclei (AGN) by accretion onto their central massive black hole with the gas in the host galaxy, take a great part in the evolution of the galaxies at all development stages. Such "feedback" of the galaxy environment by AGN including the role of their jetted outbursts generally has no evidence through the multiwavelength observations. Only a few objects are suitable for these purposes. The Perseus cluster of galaxies with the central galaxy NGC 1275 is a perfect laboratory for studying both the physics of AGN's relativistic jets and the feedback role of the central galaxy. Here, the most complete long-term observations across the electromagnetic spectrum from radio up to very-high-energy gamma rays are collected. The multiwavelength light curve provides evidence for the variability of NGC 1275 on decade timescales in the whole energy range and points to the connection of the observed activity with the launch of the features of the relativistic jets from the NGC 1275 core. The relation of multiwavelength emission components is demonstrated with spectral energy distribution and emission maps of the central part of the Perseus cluster. The evidence of the interaction of cosmic rays and magnetic fields generated in the jets at the galactic center with the gas of the Perseus cluster is obtained.}, archive = {J_ApJ}, author = {Vera G. Sinitsyna and Vera Y. Sinitsyna}, doi = {10.3847/1538-4357/adc112}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {39}, shortjournal = {The Astrophys. J.}, title = {Multiwavelength long-term studies of radio galaxy NGC 1275}, volume = {985}, year = {2025}, }
• (2025). The impact of local stellar radiation on dwarf galaxy formation around milky way analogs across cosmic reionization. ApJ, 985(1), 38. (www)

  @article{ , abstract = {We explore the effect of local stellar radiation on the formation and evolution of dwarf galaxies around Milky Way (MW) analogs. Using five simulations from the Auriga project, both with and without local stellar radiation, we find that local stellar radiation, as a pre-reionization source, is highly effective at photoionizing and heating the gas around the proto-MW analogs. As a result, the formation of surrounding dwarf galaxies in dark matter halos with masses below approximately 10 9.5 M ⊙ is significantly suppressed. After reionization, the intensity of local stellar radiation eventually becomes comparable to the ultraviolet background. Consequently, the impact of local stellar radiation on the surrounding dwarf galaxy formation decreases with decreasing redshift and nearly vanishes after redshift z = 4. At present day, the bright satellite population in the simulations with and without local stellar radiation is nearly identical. While our simulations do not have sufficient resolution to resolve the faintest satellite galaxies that are most prone to the local stellar radiation, we use the accreted galaxy mass function to assess the impact and find that the reduction in the faintest satellite is around 13% in the presence of local stellar radiation, but this difference is within  ∼2 σ of the Poisson uncertainty and thus not statistically significant.}, archive = {J_ApJ}, author = {Bocheng Zhu and Liang Gao}, doi = {10.3847/1538-4357/adc30a}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {38}, shortjournal = {The Astrophys. J.}, title = {The impact of local stellar radiation on dwarf galaxy formation around milky way analogs across cosmic reionization}, volume = {985}, year = {2025}, }
• (2025). Observations of turbulence and particle transport at interplanetary shocks: Transition of transport regimes. ApJ, 985(1), 37. (www)

  @article{ , abstract = {The transport of energetic particles is intimately related to the properties of plasma turbulence, a ubiquitous dynamic process that transfers energy across a broad range of spatial and temporal scales. However, the mechanisms governing the interactions between plasma turbulence and energetic particles are not completely understood. Here we present comprehensive observations from the upstream region of a quasi-perpendicular interplanetary (IP) shock on 2004 January 22, using data from four Cluster spacecraft to investigate the interplay between turbulence dynamics and energetic particle transport. Our observations reveal a transition in energetic proton fluxes from exponential to power-law decay with increasing distance from the IP shock. This result provides possible observational evidence of a shift in transport behavior from normal diffusion to superdiffusion. This transition correlates with an increase in the time ratio from τ s / τ c < 1 to τ s / τ c ≫ 1, where τ s is the proton isotropization time, and τ c is the turbulence correlation time. Additionally, the frequency–wavenumber distributions of magnetic energy in the power-law decay zone indicate that energetic particles excite linear Alfvén-like harmonic waves through gyroresonance, thereby modulating the original turbulence structure. These findings provide valuable insights for future studies on the propagation and acceleration of energetic particles in turbulent astrophysical and space plasma systems.}, archive = {J_ApJ}, author = {Siqi Zhao and Huirong Yan and Terry Z. Liu}, doi = {10.3847/1538-4357/adc378}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {37}, shortjournal = {The Astrophys. J.}, title = {Observations of turbulence and particle transport at interplanetary shocks: Transition of transport regimes}, volume = {985}, year = {2025}, }
• (2025). Ionized envelopes around protoplanets and the role of radiative feedback in gas accretion. ApJ, 985(1), 36. (www)

  @article{ , abstract = {Planetary growth within protoplanetary disks involves the accreting of material from their surroundings, yet the underlying mechanisms and physical conditions of the accreting gas remain debated. This study aims to investigate the dynamics and thermodynamic properties of accreting gas giants, and to characterize the envelope that forms near the planet during accretion. We employ 3D hydrodynamical simulations of a Jupiter-mass planet embedded in a viscous gaseous disk. Our models incorporate a nonisothermal energy equation to compute gas and radiation energy diffusion and include radiative feedback from the planet. The results indicate that gas accretion occurs supersonically toward the planet. The ionized envelope extends from the planetary surface up to 0.2 times the Hill radius in the no-feedback model, and up to 0.4 times the Hill radius in the feedback model. The envelope's radius, or ionization radius, acts as a boundary halting supersonic gas inflow and is pivotal for estimating accretion rates and H α emission luminosities. Including radiative feedback increases the accretion rates, especially within the ionization radius and from areas to the right of the planet when the star is positioned to the left. The accretion luminosities calculated at the ionization radius are substantially lower than those calculated at the Hill radius, highlighting potential misinterpretations in the nondetection of H α emissions as indicators of ongoing planet formation.}, archive = {J_ApJ}, author = {Matías Montesinos and Juan Garrido-Deutelmoser and Jorge Cuadra and Mario Sucerquia and Nicolás Cuello and Matthias R. Schreiber and María Paula Ronco and Octavio M. Guilera}, doi = {10.3847/1538-4357/adc392}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {36}, shortjournal = {The Astrophys. J.}, title = {Ionized envelopes around protoplanets and the role of radiative feedback in gas accretion}, volume = {985}, year = {2025}, }
• (2025). Effects of metallicity on graphite, TiC, and SiC condensation in carbon stars. ApJ, 985(1), 35. (www)

  @article{ , abstract = {From transmission electron microscopy and other laboratory studies of presolar grains, the implicit condensation sequence of carbon-bearing condensates in circumstellar envelopes of carbon stars is (from first to last) TiC-graphite-SiC. We use thermochemical equilibrium condensation calculations and show that the condensation sequence of titanium carbide (TiC), graphite (C(Gr)), and silicon carbide (SiC) depends on metallicity in addition to C/O ratio and total pressure. Calculations were performed for a characteristic carbon star ratio of C/O = 1.2 from 10 −10 to 10 −4 bars total pressure and for uniform metallicity variations ranging from 0.01 to 100 times solar elemental abundances. TiC always condenses at higher temperatures than SiC, and the carbide condensation temperatures increase with both increasing metallicity and increasing total pressure. Graphite, however, can condense in a cooling circumstellar envelope before TiC, between TiC and SiC, or after SiC, depending on the carbon-bearing gas chemistry, which is dependent on metallicity and total pressure. Analytical expressions for the graphite, TiC, and SiC condensation temperatures as functions of metallicity and total pressure are presented. The inferred sequence from laboratory presolar grain studies, TiC-graphite-SiC, is favored under equilibrium conditions at solar and subsolar metallicities between ∼10 −5 and 10 −8 bar total pressure within circumstellar envelopes of carbon stars with nominal C/O = 1.2. We also explored the dependence of the sequence at C/O ratios of 1.1 and 3.0, and found that as the C/O ratio increases, the TiC-graphite-SiC condensation sequence region occurs toward higher total pressures and lower metallicities.}, archive = {J_ApJ}, author = {Gabrielle M. Adams and Katharina Lodders}, doi = {10.3847/1538-4357/adc40f}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {35}, shortjournal = {The Astrophys. J.}, title = {Effects of metallicity on graphite, TiC, and SiC condensation in carbon stars}, volume = {985}, year = {2025}, }
• (2025). First measurements of black hole accretion and radio-jet timescales in a young quasar at the edge of reionization. ApJ, 985(1), 34. (www)

  @article{ , abstract = {We present the first study dedicated to measuring the timescales for black hole accretion and jet launching in a quasar at the edge of reionization, PSO J352.4034–15.3373 at z = 5.832 ± 0.001. Previous work presented evidence of the strong radio synchrotron emission from the jet affecting the host galaxy's dust-dominated continuum emission at ν rest = 683 GHz ( ν obs = 100 GHz), implying a break in the synchrotron spectrum. In this work, we present quasi-simultaneous observations at 1.5 GHz–42 GHz with the Karl G. Jansky Very Large Array, and derive a frequency break at {\nu }_{{\rm{rest}}}^{{\rm{break}}}=196.46 GHz ( {\nu }_{{\rm{obs}}}^{{\rm{break}}}=28.76 GHz). Modeling these observations, we calculate the jet spectral aging from the cooling of electrons to be t spec ∼ 580 yr. From this measurement, we approximate the dynamical age t dyn to be ∼2000 yr, implying a recent jet ejection. We compare the jet timescale to the quasar's lifetime ( t Q ) that indicates the duration of the latest black hole accretion event and is derived from the proximity zone size in the rest-UV/optical spectrum. However, a ghostly damped Ly α system affects this measurement yielding an upper limit of t Q ≲ 10 4 yr, consistent with the jet lifetime and indicative of a young quasar. This suggests that the triggering of a UV-bright quasar phase may occur within comparable timescales as the launch of a relativistic radio jet. Therefore, we may be witnessing an early stage of black hole and jet interactions in a quasar during the first billion years of the Universe.}, archive = {J_ApJ}, author = {Sofía Rojas-Ruiz and Emmanuel Momjian and Frederick B. Davies and Eduardo Bañados and Anna-Christina Eilers and Sarah B. Bosman and Bhargav Vaidya and Chris Carilli and Chiara Mazzucchelli and Thomas Connor and Yana Khusanova}, doi = {10.3847/1538-4357/adc4df}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {34}, shortjournal = {The Astrophys. J.}, title = {First measurements of black hole accretion and radio-jet timescales in a young quasar at the edge of reionization}, volume = {985}, year = {2025}, }
• (2025). A 50 s quasiperiodic oscillation in the early X-ray afterglow of GRB 220711B. ApJ, 985(1), 33. (www)

  @article{ , abstract = {It is generally believed that long-duration gamma-ray bursts (GRBs) originate from the core collapse of rapidly spinning massive stars, and at least some of them are powered by hyperaccreting black holes (BHs). However, definite proofs about the progenitor and central engine of these GRBs have not been directly observed in the past. Here, we report the existence of a quasiperiodic oscillation (QPO) signature with periodic frequency ∼0.02 Hz in the early X-ray afterglow phase of GRB 220711B. Such a low-frequency QPO likely signals the precession of a relativistic jet launched from a GRB hyperaccreting BH central engine. The energy injection signature from the late X-ray observations (from 5 × 10 2 s ∼ 1 × 10 4 s) is consistent with the precession hypothesis. The prompt gamma-ray light curve does not show any QPO signature, suggesting that the X-ray flaring emission in the early afterglow phase and prompt emission likely originate from different accretion processess, indicating that the progenitor stars of GRBs have a core-envelope structure with a stratified angular momentum distribution and the late-time accretion disk likely has a misalignment with respect to the rotation axis of the BH. Such a misalignment is not expected in a canonical collapsar model. As a result, the QPO signature in GRB 220711B may reveal a new formation channel of long GRBs, possibly a stellar-merger-induced core collapse, with the orbital angular momentum of the binary misaligned with the spin axis of the collapsing star.}, archive = {J_ApJ}, author = {H. Gao and W.-H. Lei and S. Xiao and Z.-P. Zhu and L. Lan and S.-K. Ai and A. Li and N. Xu and T.-C. Wang and B. Zhang and D. Xu and J. P. U. Fynbo and K. E. Heintz and P. Jakobsson and D. A. Kann and S.-Y. Fu and S.-Q. Jiang and X. Liu and S.-L. Xiong and W.-X. Peng and X.-B. Li and W.-C. Xue}, doi = {10.3847/1538-4357/adc4e2}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {33}, shortjournal = {The Astrophys. J.}, title = {A 50 s quasiperiodic oscillation in the early X-ray afterglow of GRB 220711B}, volume = {985}, year = {2025}, }
• (2025). The structure, populations, and kinematics of the milky way central and inner bulge with OGLE, APOGEE, and gaia data. ApJ, 985(1), 32. (www)

  @article{ , abstract = {We present an analysis of the structure, kinematics, and chemo-dynamical properties of the Milky Way bulge using RR Lyrae stars from Optical Gravitational Lensing Experiment (OGLE), and giant stars from APOGEE and Gaia that have distances placing them in the inner Galaxy. First, using a sample of 1879 ab-type RR Lyrae stars (RRabs) from OGLE-IV, we identified three populations: central bulge RRabs, the inner bulge RRabs, and halo or disk interlopers, based on their apocenters derived from orbital integration. Inner bulge RRabs kinematically align with the Galactic bar, while central bulge RRabs show slower rotation with lower velocity dispersion. Higher velocity dispersion stars were identified as halo/disk interlopers. Then, an orbital analysis of 28,188 APOGEE Red Clump and Red Giant Branch stars revealed kinematic properties consistent with RRabs, and the chemical abundance distribution displayed a bimodal stellar density pattern, suggesting complex star evolution histories and slightly different star formation histories for the inner bulge and central bulge. The differences in the density distribution on the ∣ Z ∣ max -eccentricity plane for the central bulge, inner bulge, and interlopers are clearly detected. It is found that the classification of bulge stars based on orbital parameters, rather than solely on metallicity, provides a more accurate population separation. As the inner bulge, which contains the highest fraction of stars, traces the bar formed by the instability of the Galactic disk, our results support that the pseudobulge is the primary origin of the bulge. Furthermore, fitting the observed data to both the boxy and X-shaped bulge models indicated a preference for the boxy bulge.}, archive = {J_ApJ}, author = {Xiao Han and Hai-Feng Wang and Giovanni Carraro and Martín López-Corredoira and Yuan-Sen Ting and Yang-Ping Luo and Guan-Yu Wang and (MWLUDPSG Collaboration)}, doi = {10.3847/1538-4357/adc4e5}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {32}, shortjournal = {The Astrophys. J.}, title = {The structure, populations, and kinematics of the milky way central and inner bulge with OGLE, APOGEE, and gaia data}, volume = {985}, year = {2025}, }
• (2025). A classification scheme for quasar absorption lines. ApJ, 985(1), 31. (www)

  @article{ , abstract = {We present a method to classify intergalactic absorption lines and apply it to 10,772 low-redshift systems. The classification gives the number of components (reflecting the kinematics) in four different ionization phases, using detections and nondetections of H i , high (O vi , N v , O v , Ne v , Ne vi , Ne viii ), medium (C iii , Si iii , O iii , O iv , C iv ) and low (C ii , N ii , O ii , Si ii , He i ) ions. In this manner, we unify the "Ly α forest," "O vi absorbers," "C iv absorbers," "Mg ii absorbers," etc. We identify three main absorber types: systems without metals (type A, 86.8% of the sample), systems with high- and/or medium-ionization ions only (type B, 10.2%), and systems with low-ionization lines (type C, 3.0%). Type A mostly has single-component systems (82.2%), type B has 43.2% single-component systems, while type C absorbers mostly have multiple hydrogen components (20.6% are single). The fraction of systems with a given number of components is basically independent of the signal-to-noise ratio. Our scheme describes the observed data for each system and can be used to define samples of similar absorbers. From absorbers with available galaxy information, we find that type A systems occur both near to and far from galaxies, type C systems trace the denser circumgalactic medium (CGM) and group gas, while type B systems trace the tenuous CGM and intergalactic medium. We present new determinations of d n / d z for the 58 most common intergalactic absorption lines. We show that a rest-frame velocity of 3000 km s −1 relative to the active galactic nucleus is preferred for separating intergalactic from associated absorbers.}, archive = {J_ApJ}, author = {Benjamin E. Rosenwasser and Bart P. Wakker and Blair D. Savage}, doi = {10.3847/1538-4357/adc4ea}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {31}, shortjournal = {The Astrophys. J.}, title = {A classification scheme for quasar absorption lines}, volume = {985}, year = {2025}, }
• (2025). The size of the continuum emission region and its scaling relations with active galactic nucleus luminosity and the broad-line region size. ApJ, 985(1), 30. (www)

  @article{ , abstract = {We present a continuum lag analysis for a sample of 37 relatively high-luminosity active galactic nuclei (AGNs) from the Seoul National University AGN Monitoring Project (SAMP), utilizing the light-curve data in B and V bands from SAMP and in g , r , i bands from the Zwicky Transient Facility. We find that the interband lags ( τ ) increase with the wavelength (i.e., τ ∝ λ ∼4/3 ) as prescribed by the standard disk model (Shakura–Sunyaev disk, hereafter SSD), suggesting consistency with the "lamp-post" reprocessing model. We report that the size of the continuum emitting region (CER) normalized at 2500 Å ( R 2500 ) is a factor of ∼5 (i.e., 0.69 ± 0.04 dex) larger than predicted by SSD. By combining our new measurements with the remeasurements of the literature sample, we report a correlation between R 2500 and AGN continuum luminosity as {R}_{2500}\,\propto \,{L}_{5100}^{0.58\pm 0.03} , which suggests that the observed continuum could be composed of both the disk emission and the diffuse emission from the broad-line region (BLR). The size of CER shows a tight relation with the size of H β BLR with a sublinear slope (i.e., {R}_{\,\rm{BLR}\,}\,\propto \,{R}_{\,\rm{2500}\,}^{0.87\pm 0.07} ) and a scatter of 0.29 dex. This empirical relation offers a promising method for estimating single-epoch black hole masses, once established over a large dynamic range of AGN luminosity.}, archive = {J_ApJ}, author = {Amit Kumar Mandal and Jong-Hak Woo and Shu Wang}, doi = {10.3847/1538-4357/adc56e}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {30}, shortjournal = {The Astrophys. J.}, title = {The size of the continuum emission region and its scaling relations with active galactic nucleus luminosity and the broad-line region size}, volume = {985}, year = {2025}, }
• (2025). Statistical analysis of compact single-source flares observed by STIX. ApJ, 985(1), 29. (www)

  @article{ , abstract = {X-ray emissions from solar flares provide a comprehensive overview of the spatial and spectral behaviors of high-temperature plasma in the solar atmosphere. In particular, compact flares are one of the best candidates for quantifying the geometrical properties of the X-ray source, which is crucial in the estimation of flare energetics. Accordingly, we present a statistical investigation of 550 flares showing one compact source in images reconstructed with the MARLIN, Expectation Maximization, and Forward Fit algorithms in the 6–10 keV soft X-ray (SXR) energy channel of the Spectrometer Telescope for Imaging X-rays (STIX), on board Solar Orbiter. We compare various properties of the sources, reconstructed with the aforesaid algorithms, which show consistency. We further test different approaches to estimating source sizes. We find better agreement between the tested algorithms using the 50% signal contour for size estimation instead of the commonly used 50% isophote. Thermal–nonthermal flare plasma parameters and energetics are investigated for a subset of flares exhibiting significant enhancement in the 12–20 keV hard X-ray (HXR) energy channel. While strong correlations are found between the emitted SXR and HXR flux with temperature, the HXR flux with nonthermal energy, and thermal with nonthermal energy, plasma parameters were not significantly correlated with the flare size or volume. The thermal–nonthermal emission partition during compact flares, characterized using the Neupert effect, is revealed only for 40% of events. We find the fraction of HXR fluence to SXR flux to be positively correlated with volume while moderately anticorrelated with density. This indicates that tenuous flare loops emit relatively less SXR emission as a response to deposited energy, compared to dense loops.}, archive = {J_ApJ}, author = {Michalina Litwicka and Tomasz Mrozek and Arun K. Awasthi and Marek Siarkowski and Marek Stęślicki and Janusz Sylwester and Barbara Sylwester}, doi = {10.3847/1538-4357/adc571}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {29}, shortjournal = {The Astrophys. J.}, title = {Statistical analysis of compact single-source flares observed by STIX}, volume = {985}, year = {2025}, }
• (2025). Revisiting the intergalactic medium around GRB 130606A and constraints on the epoch of reionization. ApJ, 985(1), 28. (www)

  @article{ , abstract = {Gamma-ray bursts (GRBs) are excellent probes of the high-redshift Universe due to their high luminosities and the relatively simple intrinsic spectra of their afterglows. They can be used to estimate the fraction of neutral hydrogen (i.e., the neutral fraction) in the intergalactic medium (IGM) at different redshifts through the examination of their Ly α damping wing with high-quality optical-to-near-infrared spectra. Neutral fraction estimates can help trace the evolution of the Epoch of Reionization (EoR), a key era of cosmological history in which the IGM underwent a phase change from neutral to ionized. We revisit GRB 130606A, a z ∼ 5.9 GRB for which multiple analyses, using the same damping-wing model and data from different telescopes, found conflicting neutral fraction results. We identify the source of the discrepant results to be differences in assumptions for key damping-wing model parameters and data range selections. We perform a new analysis implementing multiple GRB damping-wing models and find a 3 σ neutral fraction upper limit ranging from {x}_{{{\rm{H}}}_{{\rm{I}}}}\lesssim 0.20 to {x}_{{{\rm{H}}}_{{\rm{I}}}}\lesssim 0.23 . We present this result in the context of other neutral fraction estimates and EoR models, discuss the impact of relying on individual GRB lines of sight, and highlight the need for more high-redshift GRBs to effectively constrain the progression of the EoR.}, archive = {J_ApJ}, author = {H. M. Fausey and A. J. van der Horst and N. R. Tanvir and K. Wiersema and J. P U. Fynbo and D. Hartmann and A. de Ugarte Postigo}, doi = {10.3847/1538-4357/adc5fc}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {28}, shortjournal = {The Astrophys. J.}, title = {Revisiting the intergalactic medium around GRB 130606A and constraints on the epoch of reionization}, volume = {985}, year = {2025}, }
• (2025). Comparison of plasma dynamics in coronal holes and quiet sun using flux emergence simulations. ApJ, 985(1), 27. (www)

  @article{ , abstract = {This paper presents a comparison of plasma dynamics in coronal holes (CHs) and quiet Sun (QS) through 2.5D MHD flux emergence simulations. The magnetic reconnection between the emerging and the preexisting flux leads to the formation of cool, dense plasmoids with hot boundaries, and hot and cool jets with velocities ≈50 km s −1 . We perform a spectral synthesis in spectral lines probing transition region and coronal temperatures. CHs show reduced intensities, excess upflows (downflows), and widths during the jetting (downflow) period when compared to QS. During the jetting and downflow periods, the velocity and line width of the hot spectral lines in CHs show a strong positive correlation with the vertical magnetic field at z = 0, while the intensity of the cooler lines shows a weak correlation, which is not seen in QS. During the jetting period in CH, we find upflows in Si iv to be correlated (anticorrelated) with upflows (downflows) in other lines, and downflows in CH in Si iv to be correlated (anticorrelated) with upflows (downflows) in other lines when compared to QS. During the downflow, we find no strong correlation between Si iv and other line velocities. The correlation during the jetting period occurs due to coincident, cospatial origins of the hot and cool jet, while the lack of correlation during the downflow phase suggests a decoupling of hot and cool plasma. These results demonstrate that flux emergence and reconnection with preexisting flux in the atmosphere support a unified scenario for solar wind formation and coronal heating.}, archive = {J_ApJ}, author = {Vishal Upendran and Durgesh Tripathi and Bhargav Vaidya and Mark C. M. Cheung and Takaaki Yokoyama}, doi = {10.3847/1538-4357/adc5fd}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {27}, shortjournal = {The Astrophys. J.}, title = {Comparison of plasma dynamics in coronal holes and quiet sun using flux emergence simulations}, volume = {985}, year = {2025}, }
• (2025). Stellar variability toward the galactic open cluster NGC 7209. ApJ, 985(1), 26. (www)

  @article{ , abstract = {We present the analysis of stellar variability in an open cluster NGC 7209 using optical V -band CCD photometric observations. Out of 4499 stars in our study, we detected 284 candidate variables, including one identified previously. Using the machine learning algorithm HDBSCAN technique and Gaia DR3 data, we identified 246 cluster members with membership probability greater than 60%, among which 17 were identified in our study as variable stars. Based on isochrone fitting, we approximated the log(age) of the cluster to be 8.8 ± 0.2. We provide the first time-series V -band photometric study of 14 newly detected variable cluster members, detecting three potential δ Scuti, three γ Doradus, and four rotationally modulated variables, along with four possible eclipsing binaries. We detected an optical flare on 2022 November 30, from the star ID 1329 (R.A.: 331.50897; decl.: 46.44859), with an estimated emitted energy of 5.37 × 10 30 erg, which is below the typical energy range of a superflare; an error of a few tens of percent is attributed to the calculation of energy.}, archive = {J_ApJ}, author = {Dorothy M. Mwanzia and Sneh Lata and W. P. Chen and Soumen Mondal and Geoffrey Okeng’o and John Buers and Samrat Ghosh and Athul Dileep and Arjav Jain and Alisher S. Hojaev and Santosh Joshi}, doi = {10.3847/1538-4357/adc696}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {26}, shortjournal = {The Astrophys. J.}, title = {Stellar variability toward the galactic open cluster NGC 7209}, volume = {985}, year = {2025}, }
• (2025). Using machine learning to estimate near-ultraviolet magnitudes and probe quenching mechanisms of z = 0 nuggets in the RESOLVE and ECO surveys. ApJ, 985(1), 25. (www)

  @article{ , abstract = {We present a z = 0 census of nuggets—compact galaxies that form via gas-rich violent disk instability—within the luminosity- and volume-limited RESOLVED Spectroscopy Of a Local VolumE (RESOLVE) and Environmental COntext (ECO) surveys. We use random forest (RF) models to predict near-ultraviolet (NUV) magnitudes for ECO galaxies that lack high-quality NUV magnitudes, thereby doubling the number of ECO galaxies with reliable extinction-corrected star formation rates (SFRs) and red/green/blue classifications based on specific SFRs (sSFRs). The resulting RF-enhanced RESOLVE+ECO nugget sample allows us to analyze rare subpopulations—green nuggets and nuggets with active galactic nuclei (AGN)—likely associated with quenching. Green nuggets are more similar to red nuggets than to blue nuggets in halo mass ( M halo ) distribution, with both red and green nuggets being found mainly at M halo ≥ 10 11.4 M ⊙ , where permanent halo quenching is predicted. At these masses, the AGN frequency for green nuggets is higher (48.2% {}_{-5.3 \% }^{5.3 \% } ) than for either blue (39.2% {}_{-2.8 \% }^{2.9 \% } ) or red (29.3% {}_{-2.8 \% }^{3.0 \% } ) nuggets. Between M halo = 10 11.4 –10 12 M ⊙ , at the onset of permanent quenching, the AGN frequency for green nuggets is nearly double the frequency for blue or red nuggets, implying AGN are associated with this transition. At M halo < 10 11.4 M ⊙ , where temporary cyclic quenching is expected, the AGN frequency for blue nuggets (7.5% {}_{-1.2 \% }^{1.4 \% } ) is lower than for either green (31.3% {}_{-7.5 \% }^{8.7 \% } ) or red (18.8% {}_{-7.8 \% }^{11.5 \% } ) nuggets. At all masses, nuggets with AGN have reduced sSFRs and likely also atomic gas content compared to nuggets without AGN, but the quenching is more extreme below M halo = 10 11.4 M ⊙ .}, archive = {J_ApJ}, author = {Derrick S. Carr and Sheila J. Kannappan and Zackary L. Hutchens and Mugdha S. Polimera and Mark A. Norris and Kathleen D. Eckert and Amanda J. Moffett}, doi = {10.3847/1538-4357/adc71b}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {25}, shortjournal = {The Astrophys. J.}, title = {Using machine learning to estimate near-ultraviolet magnitudes and probe quenching mechanisms of z = 0 nuggets in the RESOLVE and ECO surveys}, volume = {985}, year = {2025}, }
• (2025). Unveiling the cosmic chemistry. II. “Direct” te-based metallicity of galaxies at 3 < z < 10 with JWST/NIRSpec. ApJ, 985(1), 24. (www)

  @article{ , abstract = {We report the detection of the [O iii ] auroral line in 42 galaxies within the redshift range of 3 < z < 10. These galaxies were selected from publicly available JWST data releases, including the JADES and PRIMAL surveys, and observed using both the low-resolution PRISM/CLEAR configuration and medium-resolution gratings. The measured electron temperatures in the high-ionization regions of these galaxies range from T e ([O iii ]) = 12,000 to 24,000 K, consistent with temperatures observed in local metal-poor galaxies and previous JWST studies. In 10 galaxies, we also detect the [O ii ] auroral line, allowing us to determine electron temperatures in the low-ionization regions, which range between T e ([O ii ]) = 10,830 and 20,000 K. The direct T e -based metallicities of our sample span from 12 + log(O/H) = 7.2 to 8.4, indicating these high-redshift galaxies are relatively metal-poor. By combining our sample with 25 galaxies from the literature, we expand the data set to a total of 67 galaxies within 3 < z < 10, effectively more than doubling the previous sample size for direct T e - based metallicity studies. This larger data set allows us to derive empirical metallicity calibration relations based exclusively on high-redshift galaxies, using six key line ratios: R3, R2, R23, Ne3O2, O32, and O3N2. Notably, we derive a novel metallicity calibration relation for the first time using high-redshift T e -based metallicities: \hat{R} = 0.18log R2 + 0.98log R3. This new calibration significantly reduces the scatter in high-redshift galaxies compared to the \hat{R} relation previously calibrated for low-redshift galaxies.}, archive = {J_ApJ}, author = {Priyanka Chakraborty and Arnab Sarkar and Randall Smith and Gary J. Ferland and Michael McDonald and William Forman and Mark Vogelsberger and Paul Torrey and Alex M. Garcia and Mark Bautz and Adam Foster and Eric Miller and Catherine Grant}, doi = {10.3847/1538-4357/adc7b5}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {24}, shortjournal = {The Astrophys. J.}, title = {Unveiling the cosmic chemistry. II. “Direct” te-based metallicity of galaxies at 3 < z < 10 with JWST/NIRSpec}, volume = {985}, year = {2025}, }
• (2025). Highly variable quasar candidates selected from 4XMM-DR13 with machine learning. ApJ, 985(1), 23. (www)

  @article{ , abstract = {We present a sample of 12 quasar candidates with highly variable soft X-ray emission, selected from the fourth XMM-Newton Serendipitous Source Catalog (4XMM-DR13), using random forest (RF). Optical to mid-IR photometric data for the 4XMM-DR13 sources were obtained by correlating the sample with the Sloan Digital Sky Survey (SDSS) DR18 photometric catalog and the AllWISE database. By further cross matching with known spectral catalogs from the SDSS and LAMOST surveys, we compiled a training data set containing stars, galaxies, and quasars. The RF algorithm was trained to classify the XMM–Wide-field Infrared Survey Explorer–SDSS sample. We then refined the quasar candidate selection by applying Gaia proper motion data to eliminate stellar contaminants. As a result, 52,486 quasar candidates were classified, with 8410 of them matching known quasars in SIMBAD. The quasar candidates exhibit systematically lower X-ray fluxes compared to quasars in the training set, suggesting that the classifier is effective in identifying fainter quasars. From this quasar candidate sample, we constructed a subset of 12 sources that have shown variations in their soft X-ray flux by a factor of 10 over ∼20 yr in the XMM-Newton survey. These highly variable quasar candidates extend the quasar sample characterized by extreme soft X-ray variability to the optically faint end, with magnitudes around r ∼ 22. Notably, none of these 12 sources were detected in ROSAT observations. Given the flux sensitivity of ROSAT, the result indicates that quasars exhibiting more than 2 orders of magnitude of variation are extremely rare.}, archive = {J_ApJ}, author = {Heng Wang and Yanli Ai and Yanxia Zhang and Yuming Fu and Wenfeng Wen and Liming Dou and Xue-Bing Wu and Xiangru Li and Zhiying Huo}, doi = {10.3847/1538-4357/adc7b8}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {23}, shortjournal = {The Astrophys. J.}, title = {Highly variable quasar candidates selected from 4XMM-DR13 with machine learning}, volume = {985}, year = {2025}, }
• (2025). The tidal torque theory revisited. i. protohalo angular momentum. ApJ, 985(1), 22. (www)

  @article{ , abstract = {In tidal torque theory, the angular momentum (AM) of dark matter halos arises from the tidal torque suffered by aspherical collapsing patches due to surrounding mass fluctuations. This theory was implemented in the peak model, where protohalos are ellipsoidal. However, the adopted delimitations of these objects were doubtful and the protohalo AM was calculated numerically, which complicated the interpretation of the result and compromised its applicability. In addition, the AM of the final halos was derived without taking into account nonlinear effects. Here, we rederive the protohalo AM in the peak model, delimiting ellipsoids in the usual natural way and following a novel fully analytic approach that leads to a very simple and practical expression. The predicted AM is shown to fully agree with the results of cosmological simulations. In the following Paper II, we will apply this model to infer the rotational properties of relaxed halos, accounting for shell crossing and major mergers.}, archive = {J_ApJ}, author = {Eduard Salvador-Solé and Alberto Manrique}, doi = {10.3847/1538-4357/adc7ba}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {22}, shortjournal = {The Astrophys. J.}, title = {The tidal torque theory revisited. i. protohalo angular momentum}, volume = {985}, year = {2025}, }
• (2025). EP240414a: Off-axis view of a jet-cocoon system from an expanded progenitor star. ApJ, 985(1), 21. (www)

  @article{ , abstract = {When a relativistic jet is launched following the core collapse of a star, its interaction with the stellar envelope leads to the formation of a hot cocoon, which produces various viewing-angle-dependent observational phenomena following the breakout from the surface. We study the observational signatures of fast X-ray transient (FXT) EP240414a, which may originate from a jet-cocoon system viewed slightly off-axis. In our model, (1) the prompt X-ray emission lasting ∼100 s is attributed to the cooling emission from the inner cocoon (shocked jet material); (2) the ∼0.1 day X-ray emission comes from the inner cocoon's afterglow; (3) the ∼0.4 day thermal-dominated optical emission arises from the cooling of the outer cocoon (shocked stellar material); (4) the ∼3 day nonthermal optical component and subsequent radio emission can be explained by the afterglow from a jet with a viewing angle of 10 ∘ ≲ θ v ≲ 15 ∘ ; and (5) the associated broad-lined Type Ic supernova only dominates the optical emission after ∼7 days. Both the jet inferred from the off-axis afterglow and the inner cocoon constrained by the cooling emission are found to have similar kinetic energies, on the order of 10 51 erg. We find that the progenitor's radius is ∼3 R ⊙ as constrained by the inner cocoon's cooling emissions, indicating that the preexplosion star may be a massive helium star that is slightly inflated. More FXTs associated with off-axis jets and supernovae will be further examined by the Einstein Probe, leading to a deeper understanding of jet-cocoon systems.}, archive = {J_ApJ}, author = {Jian-He Zheng and Jin-Ping Zhu and Wenbin Lu and Bing Zhang}, doi = {10.3847/1538-4357/adc993}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {21}, shortjournal = {The Astrophys. J.}, title = {EP240414a: Off-axis view of a jet-cocoon system from an expanded progenitor star}, volume = {985}, year = {2025}, }
• (2025). A data-constrained magnetohydrodynamic simulation of successive X-class flares in solar active region 13842. i. dynamics of the solar eruption associated with the x7.1 solar flare. ApJ, 985(1), 20. (www)

  @article{ , abstract = {We investigated the initiation and the evolution of an X7.1-class solar flare observed in NOAA Active Region 13842 on 2024 October 1, based on a data-constrained magnetohydrodynamic (MHD) simulation. The nonlinear force-free field (NLFFF) extrapolated from the photospheric magnetic field about 1 hr before the flare was used as the initial condition for the MHD simulations. The NLFFF reproduces highly sheared field lines that undergo tether-cutting reconnection in the MHD simulation, leading to the formation of a highly twisted magnetic flux rope (MFR), which then erupts rapidly, driven by both torus instability and magnetic reconnection. This paper focuses on the dynamics of the MFR and its role in eruptions. We find that magnetic reconnection in the preeruption phase is crucial in the subsequent eruption driven by the torus instability. Furthermore, our simulation indicates that magnetic reconnection also directly enhances the torus instability. These results suggest that magnetic reconnection is not just a by-product of the eruption due to reconnecting of postflare arcade, but also plays a significant role in accelerating the MFR during the eruption.}, archive = {J_ApJ}, author = {Keitarou Matsumoto and Satoshi Inoue and Nian Liu and Keiji Hayashi and Ju Jing and Haimin Wang}, doi = {10.3847/1538-4357/adcac2}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {20}, shortjournal = {The Astrophys. J.}, title = {A data-constrained magnetohydrodynamic simulation of successive X-class flares in solar active region 13842. i. dynamics of the solar eruption associated with the x7.1 solar flare}, volume = {985}, year = {2025}, }
• (2025). Impulsive solar flares in the parker solar probe era. i. low-energy electron, proton, and alpha beams. ApJ, 985(1), 19. (www)

  @article{ , abstract = {Multiple instruments on board the Parker Solar Probe spacecraft have detected signatures of impulsive electron and ion beam events over the course of the first 20 encounters. The energy spectra of these events are characterized by a peak originating in the low-frequency bandwidth of the FIELDS sensor and descending over time in energy until it merges with the bulk of the solar wind as observed by the Solar Wind Electrons, Alphas, and Protons suite. All events are well associated with Type III radio bursts, and some are well correlated with soft and hard X-rays generated by impulsive solar flares. These dispersive energy beam phenomena are essential in understanding particle acceleration, transport, and energy partitioning between electrons and ions as a result of impulsive solar flares. In this work, we present an analysis of said events and leverage multiwavelength observations that are conducted by instruments on multiple platforms. Our results show, for the first time, that solar flares are observed to be the source of low-energy ions in interplanetary space. This discovery has never been previously observed at such low energies by instruments at 1 au.}, archive = {J_ApJ}, author = {S. T. Alnussirat and D. E. Larson and R. Livi and P. L. Whittlesey and A. Rahmati and O. Romeo and J. Huang and Mingzhe Liu and M. Pulupa and S. D. Bale and N. Raouafi and D. J. McComas}, doi = {10.3847/1538-4357/adcd63}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {19}, shortjournal = {The Astrophys. J.}, title = {Impulsive solar flares in the parker solar probe era. i. low-energy electron, proton, and alpha beams}, volume = {985}, year = {2025}, }
• (2025). Theory of the kinetic helicity effect on turbulent diffusion of magnetic and scalar fields. ApJ, 985(1), 18. (www)

  @article{ , abstract = {Kinetic helicity is a fundamental characteristic of astrophysical turbulent flows. It is not only responsible for the generation of large-scale magnetic fields in the Sun, stars, and spiral galaxies, but it also affects turbulent diffusion, resulting in the dissipation of large-scale magnetic fields. Using the path integral approach for random helical velocity fields with a finite correlation time and large Reynolds numbers, we show that turbulent magnetic diffusion is reduced by the kinetic helicity, while the turbulent diffusivity of a passive scalar is enhanced by the helicity. The latter can explain the results of recent numerical simulations for forced helical turbulence. One of the crucial reasons for the difference between the kinetic helicity effect on magnetic and scalar fields is related to the helicity dependence of the correlation time of a turbulent velocity field.}, archive = {J_ApJ}, author = {Igor Rogachevskii and Nathan Kleeorin and Axel Brandenburg}, doi = {10.3847/1538-4357/adcec0}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {18}, shortjournal = {The Astrophys. J.}, title = {Theory of the kinetic helicity effect on turbulent diffusion of magnetic and scalar fields}, volume = {985}, year = {2025}, }
• (2025). Sequential ejections of plasma blobs due to unbraiding of tangled loops in the solar atmosphere. ApJ, 985(1), 17. (www)

  @article{ , abstract = {Nanoflares, which are consequences of braids in tangled magnetic fields, are an important candidate to heat the solar corona to a million degrees. However, their observational evidence is sparse, and many of their observational characteristics are yet to be discovered. With the high-resolution observations taken by the Extreme Ultraviolet Imager onboard the Solar Orbiter, here we study a series of ejections of plasma blobs resulting from braided magnetic loops in the upper transition region and reveal some critical characteristics of such processes. The cores of these ejections have a size of about 700 km, a duration of less than 1 minute, and a speed of about 90 km s −1 . An important characteristic is that these plasma blobs are apparently constrained by the postreconnection magnetic loops, along which they show an extension of up to about 2000 km. The propagation of unbraiding nodes along the main axis of the tangled loops has a speed of about 45 km s −1 . The separation angles between the postreconnection loops and the main axis of the tangled loops are about 30°. The observations from the Atmospheric Imaging Assembly reveal that the braiding loops are upper transition region structures. Based on these observations, the typical magnetic free energy producing a blob is estimated to be about 3.4 × 10 23 erg, well in the nanoflare regime, while the kinematic energy of a blob is about 2.3 × 10 23 erg, suggesting that a majority of magnetic free energy in a magnetic braid is likely transferred into kinematic energy.}, archive = {J_ApJ}, author = {Xiuhui Zuo and Zhenghua Huang and Hengyuan Wei and Chao Zhang and Boyu Sun and Youqian Qi and Hui Fu and Weixin Liu and Mingzhe Sun and Ming Xiong and Lidong Xia}, doi = {10.3847/1538-4357/adcf1c}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {17}, shortjournal = {The Astrophys. J.}, title = {Sequential ejections of plasma blobs due to unbraiding of tangled loops in the solar atmosphere}, volume = {985}, year = {2025}, }
• (2025). Connecting a magnetized disk to a convective low-mass protostar: A global 3D model of boundary layer accretion. ApJ, 985(1), 16. (www)

  @article{ , abstract = {In the early stages of star formation, boundary layer accretion, where protostars accrete material from disks extending down to their surfaces, plays a crucial role. Understanding how a magnetorotational-instability (MRI)-active disk connects to a protostar's surface remains a significant challenge. To investigate the mechanisms of mass and angular momentum transfer, we develop a global, 3D magnetohydrodynamic model of boundary layer accretion around a magnetized, convective low-mass protostar. Our results reveal that angular momentum transport mechanisms transition significantly from the outer MRI-active disk to the protostellar surface. Various mechanisms—MRI, spiral shocks, coronal accretion, jets, and disk winds—contribute to angular momentum transfer, resulting in three distinct disk structures: (1) the MRI-active disk, (2) the transition layer, and (3) the boundary layer. The simulated protostar is strongly magnetized due to the accumulation of the disk fields, wrapping by disk toroidal fields, and stellar dynamo activity. Magnetic concentrations analogous to starspots form on the protostar and interact with the rotating disk gas to generate spiral shocks. These shocks play a key role in driving accretion. These findings demonstrate the necessity of global MHD models for a comprehensive understanding of angular momentum transport. Additionally, we identify explosive events triggered by magnetic reconnection in both the protostar and the disk atmosphere. We also find decretion flows in the disk midplane, which may be important for the radial transport of refractory materials, such as calcium-aluminum-rich inclusions precursor gas, to the outer disk.}, archive = {J_ApJ}, author = {Shinsuke Takasao and Takashi Hosokawa and Kengo Tomida and Kazunari Iwasaki}, doi = {10.3847/1538-4357/adc37b}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {16}, shortjournal = {The Astrophys. J.}, title = {Connecting a magnetized disk to a convective low-mass protostar: A global 3D model of boundary layer accretion}, volume = {985}, year = {2025}, }
• (2025). Mapping galactic dust emission and extinction with h i, h II, and h2. ApJ, 985(1), 15. (www)

  @article{ , abstract = {Neutral hydrogen (H i ) emission closely traces the dust column density at high Galactic latitudes and is thus a powerful tool for predicting dust extinction. However, the relation between H i column density N HI and high-latitude dust emission observed by Planck has large-scale residuals at the level of ≲20% on tens of degree scales. In this work, we improve H i -based dust templates in the north/south Galactic poles covering a sky fraction of f sky = 13.5%/11.0% (5577/4555 deg 2 ) by incorporating data from ionized (H ii ) and molecular (H 2 ) gas phases. We make further improvements by employing a clustering analysis on the H i spectral data to identify discrete clouds with distinct dust properties. However, only a modest reduction in fitting residuals is achieved. We quantify the contributions to these residuals from variations in the dust-to-gas ratio, dust temperature and opacity, and magnetic field orientation using ancillary data sets. Although residuals in a few particular regions can be attributed to these factors, no single explanation accounts for the majority. Assuming a constant dust temperature along each line of sight, we derive an upper limit on the high-latitude dust temperature variation of σ T < 1.28 K, lower than the temperature variation reported in previous studies. Joint analysis of multiple existing and upcoming data sets that trace Galactic gas and dust properties is needed to clarify the origins of the variation of gas and dust properties found here and to significantly improve gas-based extinction maps.}, archive = {J_ApJ}, author = {Yun-Ting Cheng and Brandon S. Hensley and Tzu-Ching Chang and Olivier Doré}, doi = {10.3847/1538-4357/adc693}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {15}, shortjournal = {The Astrophys. J.}, title = {Mapping galactic dust emission and extinction with h i, h II, and h2}, volume = {985}, year = {2025}, }
• (2025). Cloud-scale gas properties, depletion times, and star formation efficiency per freefall time in PHANGS–ALMA. ApJ, 985(1), 14. (www)

  @article{ , abstract = {We compare measurements of star formation efficiency to cloud-scale gas properties across the PHANGS– ALMA sample. Dividing 67 galaxies into 1.5 kpc scale regions, we calculate the molecular gas depletion time {\tau }_{{\rm{dep}}}^{{\rm{mol}}}={{\rm{\Sigma }}}_{{\rm{mol}}}/{{\rm{\Sigma }}}_{{\rm{SFR}}} and the star formation efficiency per freefall time {\epsilon }_{{\rm{ff}}}^{{\rm{mol}}}={\tau }_{{\rm{ff}}}/{\tau }_{{\rm{dep}}}^{{\rm{mol}}} for each region. Then we test how {\tau }_{{\rm{dep}}}^{{\rm{mol}}} and {\epsilon }_{{\rm{ff}}}^{{\rm{mol}}} vary as functions of the regional mass-weighted mean molecular gas properties on cloud scales (60–150 pc): gas surface density, \langle {{\rm{\Sigma }}}_{{\rm{mol}}}^{{\rm{cloud}}}\rangle , velocity dispersion, \langle {\sigma }_{{\rm{mol}}}^{{\rm{cloud}}}\rangle , virial parameter, \langle {\alpha }_{{\rm{vir}}}^{{\rm{cloud}}}\rangle , and gravitational freefall time, \langle {\tau }_{{\rm{ff}}}^{{\rm{cloud}}}\rangle . \langle {\tau }_{{\rm{ff}}}^{{\rm{cloud}}}\rangle and {\tau }_{{\rm{dep}}}^{{\rm{mol}}} correlate positively, consistent with the expectation that gas density plays a key role in setting the rate of star formation. Our fiducial measurements suggest {\tau }_{{\rm{dep}}}^{{\rm{mol}}}\propto {\langle {\tau }_{{\rm{ff}}}^{{\rm{cloud}}}\rangle }^{0.5} and {\epsilon }_{{\rm{ff}}}^{{\rm{mol}}}\approx 0.34 \% , though the exact numbers depend on the adopted fitting methods. We also observe anticorrelations between {\tau }_{{\rm{dep}}}^{{\rm{mol}}} and \langle {{\rm{\Sigma }}}_{{\rm{mol}}}^{{\rm{cloud}}}\rangle and between {\tau }_{{\rm{dep}}}^{{\rm{mol}}} and \langle {\sigma }_{{\rm{mol}}}^{{\rm{cloud}}}\rangle . All three correlations may reflect the same underlying link between density and star formation efficiency combined with systematic variations in the degree to which self-gravity binds molecular gas in galaxies. We highlight the {\tau }_{{\rm{dep}}}^{{\rm{mol}}} – \langle {\sigma }_{{\rm{mol}}}^{{\rm{cloud}}}\rangle relation because of the lower degree of correlation between the axes. Contrary to theoretical expectations, we observe an anticorrelation between {\tau }_{{\rm{dep}}}^{{\rm{mol}}} and \langle {\alpha }_{{\rm{vir}}}^{{\rm{cloud}}}\rangle and no significant correlation between {\epsilon }_{{\rm{ff}}}^{{\rm{mol}}} and \langle {\alpha }_{{\rm{vir}}}^{{\rm{cloud}}}\rangle . Our results depend sensitively on the adopted CO-to-H 2 conversion factor, with corrections for excitation and emissivity effects in inner galaxies playing an important role. We emphasize that our simple methodology and clean selection allow for easy comparison to numerical simulations and highlight this as a logical next direction.}, archive = {J_ApJ}, author = {Adam K. Leroy and Jiayi Sun and Sharon Meidt and Oscar Agertz and I-Da Chiang and Jindra Gensior and Simon C. O. Glover and Oleg Y. Gnedin and Annie Hughes and Eva Schinnerer and Ashley T. Barnes and Frank Bigiel and Alberto D. Bolatto and Dario Colombo and Jakob den Brok and Mélanie Chevance and Ryan Chown and Cosima Eibensteiner and Damian R. Gleis and Kathryn Grasha and Jonathan D. Henshaw and Ralf S. Klessen and Eric W. Koch and Elias K. Oakes and Hsi-An Pan and Miguel Querejeta and Erik Rosolowsky and Toshiki Saito and Karin Sandstrom and Sumit K. Sarbadhicary and Yu-Hsuan Teng and Antonio Usero and Dyas Utomo and Thomas G. Williams}, doi = {10.3847/1538-4357/adbcab}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {14}, shortjournal = {The Astrophys. J.}, title = {Cloud-scale gas properties, depletion times, and star formation efficiency per freefall time in PHANGS–ALMA}, volume = {985}, year = {2025}, }
• (2025). Estimating the poynting flux of alfvénic waves in polar coronal holes across solar cycle 24. ApJ, 985(1), 13. (www)

  @article{ , abstract = {Alfvénic waves are known to be prevalent throughout the corona and solar wind. Determining the Poynting flux supplied by the waves is required for constraining their role in plasma heating and acceleration, as well as providing a constraint for Alfvén-wave-driven models that aim to predict coronal and solar wind properties. Previous studies of the Alfvénic waves in polar coronal holes have been able to provide a measure of energy flux for arbitrary case studies. Here, we build upon previous work and take a more systematic approach, examining if there is evidence for any variation in vertical Poynting flux over the course of the solar cycle. We use imaging data from the Solar Dynamics Observatory's Atmospheric Imaging Assembly to measure the displacements of the fine-scale structure present in coronal holes. It is found that the measure for vertical Poynting flux is broadly similar over the solar cycle, implying a consistent contribution from waves to the energy budget of the solar wind. There is variation in energy flux across the measurements (around 30%), but this is suggested to be due to differences in the individual coronal holes rather than a feature of the solar cycle. Our direct estimates are in agreement with recent studies by Z. Huang et al., who constrain the vertical Poynting flux through comparison of predicted wind properties from Alfvénic-wave-driven turbulence models to those observed with OMNI at 1 au. Taken together, both sets of results points toward a lack of correlation between the coronal Poynting flux from waves and the solar cycle.}, archive = {J_ApJ}, author = {R. J. Morton and M. J. Weberg and N. Balodhi and J. A. McLaughlin}, doi = {10.3847/1538-4357/adc568}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {13}, shortjournal = {The Astrophys. J.}, title = {Estimating the poynting flux of alfvénic waves in polar coronal holes across solar cycle 24}, volume = {985}, year = {2025}, }
• (2025). On neutron star natal kicks in high-mass X-ray binaries: Insights from population synthesis. ApJ, 985(1), 12. (www)

  @article{ , abstract = {The motion of neutron stars (NSs) in the Galaxy is largely dependent on natal kicks received by the NSs during supernova explosions. Thus, the measured peculiar velocities of NS high-mass X-ray binaries (HMXBs) provide valuable clues to natal kicks, which also play an important role in the evolution of HMXBs. In this work, we collect proper motions, radial velocities, and parallaxes for 36 NS HMXBs to derive their peculiar velocities at the birth of the NSs. We then use binary population synthesis to simulate the velocities of NS HMXBs with various choices of the kick velocity distribution for both core-collapse and electron-capture supernovae. Comparing the simulated and measured velocities, orbital periods, and eccentricities, we show that the natal kick distribution that can best match the observations is characterized by a bimodal Maxwellian distribution with σ 1 = 320 km s −1 (for core-collapse supernovae) and σ 2 = 80 km s −1 (for electron-capture supernovae) and the He core mass for the latter in the range of (1.83–2.25) M ⊙ . Our findings provide useful insights for further population synthesis and binary evolution studies of NS binaries.}, archive = {J_ApJ}, author = {Xiangyu Ivy Wang and Xiang-Dong Li}, doi = {10.3847/1538-4357/adc56f}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {12}, shortjournal = {The Astrophys. J.}, title = {On neutron star natal kicks in high-mass X-ray binaries: Insights from population synthesis}, volume = {985}, year = {2025}, }
• (2025). A detailed single-pulse study of four-component pulsar PSR j1239+0326 discovered by FAST. ApJ, 985(1), 11. (www)

  @article{ , abstract = {We report on a single-pulse study of PSR J1239+0326 discovered by the Five-hundred-meter Aperture Spherical radio Telescope (FAST) in the Commensal Radio Astronomy FAST Survey. The observations were conducted at a central frequency of 1.25 GHz. The integrated pulse profile of PSR J1239+0326 shows four distinct components, implying a central line of sight traversing a presumed double cone core emission beam. We found correlations between intensities of the first and fourth components and the second and the core components, indicating that the charges emitted between the correlated components may be related. Based on rotating vector model fitting, we estimated the inclination angle between the magnetic and the rotational axes to be 10°. No nulls, giant pulses, or giant micropulses were detected during observation sessions. Outer-cone components are observed to display "even-odd" subpulse modulation with quasiperiodicity around 2 P , where P is the rotational period of the pulsar. The trailing component exhibits energy modulation with quasiperiodicities of 19 P and 26 P . This two-mode modulation could result from the combination of sub-pulse drifts and the feedback between the voltage difference across the polar gap and surface thermal emission by backflowing charges.}, archive = {J_ApJ}, author = {R. Rejep and W. W. Zhu and N. Wang and W. M. Yan and J. P. Yuan and M. Kramer and L. Q. Meng and E. Gügercinoğlu and M. Yuan and W. Y. Wang and Z. W. Wu and Q. D. Wu and D. Zhao and S. Q. Wang and H. M. Tedila and S. J. Dang and M. Y. Xue and P. Wang and The FAST Collaboration}, doi = {10.3847/1538-4357/adc576}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {11}, shortjournal = {The Astrophys. J.}, title = {A detailed single-pulse study of four-component pulsar PSR j1239+0326 discovered by FAST}, volume = {985}, year = {2025}, }
• (2025). The spheroidal analog method for modeling irregular porous aggregates. ApJ, 985(1), 10. (www)

  @article{ , abstract = {It is shown that the optical properties of an irregular porous grain with effective radius a eff ≲ 3 λ (where λ is the wavelength) can be well approximated by a "spheroidal analog": a spheroid with appropriate axial ratio and size, with a dielectric function obtained from an effective medium theory. Prescriptions for specifying the axial ratio and porosity of the spheroidal analog, based on simple geometric properties, are given. The accuracy of the spheroidal analog method is studied for irregular grains with a range of structures and porosities. Different effective medium theories are compared; Bruggeman's theory is found to give the best results. The accuracy of the spheroidal analog method justifies the use of spheroids for modeling absorption, scattering, and polarization by interstellar, circumstellar, or interplanetary dust.}, archive = {J_ApJ}, author = {B. T. Draine}, doi = {10.3847/1538-4357/adc57d}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {10}, shortjournal = {The Astrophys. J.}, title = {The spheroidal analog method for modeling irregular porous aggregates}, volume = {985}, year = {2025}, }
• (2025). Overall ultra-high energy neutrino emission from GRBs during jet expansion. ApJ, 985(1), 9. (www)

  @article{ , abstract = {The ultrarelativistic jet released in gamma-ray bursts (GRBs) is expected to produce ultra-high-energy cosmic rays (UHECRs), prompt gamma-ray emission, and hence prompt high-energy neutrinos by photopion interactions. In this work, we calculate the time-integrated neutrino spectrum during the expansion of jets by taking into account the time evolution of cosmic-ray and secondary spectra and neutrino production. We numerically solve the continuity equations for nucleons, pions, and muons for their spectral evolution. Since pion and muon damping weakens as the jet expands, the neutrino production at large radii at high energies may dominate that around the jet energy dissipation radius. Compared with the usually adopted approaches that only consider neutrino production around the energy dissipation radius, the overall UHE neutrino fluence integrated over time can be significantly larger, and the flavor fraction of electron neutrinos as function of neutrino energy is different at UHE, due to neutrino production at radii much larger than the energy dissipation radius. The faster magnetic field decay leads to larger UHE neutrino fluence, and the UHE neutrino spectra are weakly dependent on the energy dissipation radius and the jet Lorentz factor. Observations of prompt EeV neutrinos from GRBs by the next-generation neutrino telescopes, e.g., GRAND and IceCube-Gen2, will test the hypothesis of GRBs as UHECR sources and probe the physics of GRB jets.}, archive = {J_ApJ}, author = {Qinyuan Zhang and Zhuo Li}, doi = {10.3847/1538-4357/adc68e}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {9}, shortjournal = {The Astrophys. J.}, title = {Overall ultra-high energy neutrino emission from GRBs during jet expansion}, volume = {985}, year = {2025}, }
• (2025). Asteroseismic analysis of a red giant KIC 9145955 by including the small-scale magnetic fields in the atmosphere. ApJ, 985(1), 8. (www)

  @article{ , abstract = {Recent convincing evidence is found within asteroseismology that suggests the magnetic fields exist in three red giants. Research on small-scale magnetic fields in the Sun and HD 49385 has shown that they have a certain corrective effect on the systematic discrepancies between observed and theoretical frequencies. Here we apply a similar method applied for the Sun to a red giant, KIC 9145955, to explore the impact of small-scale magnetic fields in the photosphere on its frequencies. We find that the calculated frequencies of our best-fit model, which simulates the effect of the magnetic fields by artificially modifying the Eddington T − τ relation, perfectly match those of the observed l = 0, 1, and 2 modes, indicating the existence of small-scale magnetic fields with an upper strength limit of 65 G and concentrating at a height 13,100 km in the photosphere. Based on the best-fit model, we revise the stellar parameters of KIC 9145955 as M = 1.23 ± 0.04 M ⊙ , R = 5.57 ± 0.06 R ⊙ , L = 19.85 ± 0.5 L ⊙ , Age = 3.83 ± 0.5 Gyr, M He = 0.2108 ± 0.0005 M ⊙ , and R He = 0.0306 ± 0.0001 R ⊙ .}, archive = {J_ApJ}, author = {Yuetong Wang and Guifang Lin and Yan Li and Tao Wu and Yaguang Li}, doi = {10.3847/1538-4357/adc71a}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {8}, shortjournal = {The Astrophys. J.}, title = {Asteroseismic analysis of a red giant KIC 9145955 by including the small-scale magnetic fields in the atmosphere}, volume = {985}, year = {2025}, }
• (2025). Dependence of planet populations on stellar mass and metallicity: A pebble-accretion-based planet population synthesis model. ApJ, 985(1), 7. (www)

  @article{ , abstract = {The formation and evolution of planetary systems are linked to their host stellar environment. In this study, we employ a pebble-accretion-based planet population synthesis model to explore the correlation between planetary properties and stellar mass/metallicity. Our numerical results reproduce several main aspects of exoplanetary observations. First, we find that the occurrence rate of super-Earths, η SE , follows an inverted V-shape in relation to stellar mass: it increases with stellar mass among lower-mass dwarfs, peaks at early M dwarfs, and declines toward higher-mass GK stars. Second, super-Earths grow ubiquitously around stars with various metallicities, exhibiting a flat or weak η SE dependence on Z ⋆ . Third, giant planets in contrast form more frequently around stars with higher mass/metallicity. Lastly, we extend a subset of simulations to 1 Gyr to investigate the long-term evolution of the systems' architecture. By converting our simulated systems into synthetic observations, we find that the eccentricities and inclinations of single-transit systems increase with stellar metallicity, while these dependencies in multiplanet systems remains relatively weak. The alignment between our results and observations provides key insights into the connection between planet populations and stellar properties.}, archive = {J_ApJ}, author = {Mengrui Pan and Beibei Liu and Linjie Jiang and Jiwei Xie and Wei Zhu and Ignasi Ribas}, doi = {10.3847/1538-4357/adc7a9}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {7}, shortjournal = {The Astrophys. J.}, title = {Dependence of planet populations on stellar mass and metallicity: A pebble-accretion-based planet population synthesis model}, volume = {985}, year = {2025}, }
• (2025). An anisotropic plasma model of the heliospheric interface. ApJ, 985(1), 6. (www)

  @article{ , abstract = {We present a pioneering model of the interaction between the solar wind and the surrounding interstellar medium that includes the possibility of different pressures in directions parallel and perpendicular to the magnetic field. The outer heliosheath region is characterized by a low rate of turbulent scattering that would permit development of pressure anisotropy. The effect is best seen on the interstellar side of the heliopause, where a narrow region develops with an excessive perpendicular pressure resembling a plasma depletion layer typical of planetary magnetospheres. The magnitude of this effect for typical heliospheric conditions is relatively small owing to proton–proton collisions. We show, however, that if the circumstellar medium is warm and tenuous, a much broader anisotropic boundary layer can exist, with a dominant perpendicular pressure in the southern hemisphere and a dominant parallel pressure in the north.}, archive = {J_ApJ}, author = {Vladimir Florinski and Dinshaw S. Balsara and Deepak Bhoriya and Gary P. Zank and Shishir Biswas and Swati Sharma and Sethupathy Subramanian}, doi = {10.3847/1538-4357/adc80d}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {6}, shortjournal = {The Astrophys. J.}, title = {An anisotropic plasma model of the heliospheric interface}, volume = {985}, year = {2025}, }
• (2025). Scattering blanketing effect of earth’s proto-atmosphere: Enhanced suppression of planetary radiation and magma ocean cooling. ApJ, 985(1), 5. (www)

  @article{ , abstract = {The thermal evolution of magma oceans formed by giant impacts is strongly influenced by a proto-atmosphere through its blanketing effect, which suppresses outgoing planetary radiation. While both radiative absorption and Rayleigh scattering by atmospheric species can contribute to this effect, the role of the scattering in suppressing thermal radiation from magma oceans remains unclear. In this study, we develop a 1D radiative transfer model for planetary and solar radiation in a proto-atmosphere composed of H 2 O and H 2 , and a coupled thermal evolution model of a planetary interior and proto-atmosphere, to investigate the scattering blanketing effect on planetary radiation and magma ocean cooling. Our results show that Rayleigh scattering significantly reduces the outgoing planetary radiation at wavelengths below  ∼1 μ m, particularly in hot, thick atmospheres where scattering is highly effective. Consequently, the planetary outgoing radiation flux decreases by up to about 1 to 2 orders of magnitude and the magma ocean lifetime is prolonged by up to about three times due to the scattering blanketing effect when the total amounts of H 2 O and H 2 are equivalent to or greater than the present-day terrestrial seawater. These findings suggest that the prolonged magma ocean phase facilitated efficient differentiation between compatible and incompatible elements, even in the lower mantle. Furthermore, they imply that sustained magma oceans likely persisted throughout much of the giant impact phase, supporting a magma ocean origin of the Moon, consistent with its observed chemical characteristics.}, archive = {J_ApJ}, author = {Tatsuya Yoshida and Kirara Arima and Takeshi Kuroda and Naoki Terada and Kiyoshi Kuramoto}, doi = {10.3847/1538-4357/adc8a5}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {5}, shortjournal = {The Astrophys. J.}, title = {Scattering blanketing effect of earth’s proto-atmosphere: Enhanced suppression of planetary radiation and magma ocean cooling}, volume = {985}, year = {2025}, }
• (2025). Chemical components in the virgo overdensity and Hercules–Aquila cloud: Hints of more than one merger event in GSE-like debris. ApJ, 985(1), 4. (www)

  @article{ , abstract = {Using elemental abundances for 1.26 million K giants in the Large Sky Area Multi-Object Fiber Spectroscopic Telescope DR8 value-added catalog, we analyze the chemical abundances of the Virgo Overdensity and Hercules–Aquila Cloud. We find two distinct chemical populations in both overdensities, which is in disagreement with the mainstream hypothesis that both overdensities are composed of materials from a single merger event, namely, Gaia–Sausage–Enceladus (GSE). The two populations show different chemical trends: one exhibits low metallicities and high α abundances, and the other shows high metallicities and low α abundances, which are associated with the recently discovered Nereus and Virgo Radial Merger (VRM) components in the local stellar halo, respectively. The Nereus component in these overdensities uniquely exhibits a decreasing trend in the [Fe/H]–[Mn/Fe] plane. Out of all observed Milky Way dwarf galaxies, this trend is only found in the Sculptor dwarf galaxy, which provides clues for the properties of Nereus progenitor. We also find that the velocity ellipses with high anisotropy parameters that is usually considered to be part of GSE are actually a mix of the two components. Both overdensities are well mixed in kinematic spaces, confirming recent claims that the debris of merger pairs are kinematically indistinguishable in a recent simulation. We find that the velocity ellipses of the VRM stars in these overdensities have large inclination angles, which may be an indication of the merger time in simulated merger events.}, archive = {J_ApJ}, author = {Haoyang Liu and Cuihua Du and Thomas Donlon and Mingji Deng}, doi = {10.3847/1538-4357/adc8a8}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {4}, shortjournal = {The Astrophys. J.}, title = {Chemical components in the virgo overdensity and Hercules–Aquila cloud: Hints of more than one merger event in GSE-like debris}, volume = {985}, year = {2025}, }
• (2025). Potential flow theory formulation of parker’s unsteady solar wind model and nonlinear stability of parker’s steady solar wind solution. ApJ, 985(1), 3. (www)

  @article{ , abstract = {The purpose of this paper is to present a novel optimal theoretical framework based on potential flow theory in ideal gas dynamics, which provides a smooth extrapolation of Parker's steady solar wind model to the unsteady case. The viability of this framework is illustrated by providing the first ever systematic theoretical formulation to successfully address the long-standing open issue of regularization of the singularity associated with the Parker sonic critical point (where the solar wind flow velocity equals the speed of sound in the gas) in the linear stability problem of Parker's steady solar wind solution. This development involves going outside the framework of the linear perturbation problem and incorporating the dominant nonlinearities in this dynamical system, and hence provides an appropriate nonlinear recipe to regularize this singularity. The stability of Parker's steady wind solution is found to also extend to the neighborhood of the Parker sonic critical point upon analyzing the concomitant nonlinear problem. The new theoretical framework given here seems, therefore, to have the potential to provide a viable basis for future formulations addressing various theoretical aspects of the unsteady version of Parker's steady solar wind model.}, archive = {J_ApJ}, author = {Bhimsen K. Shivamoggi}, doi = {10.3847/1538-4357/adcd64}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {3}, shortjournal = {The Astrophys. J.}, title = {Potential flow theory formulation of parker’s unsteady solar wind model and nonlinear stability of parker’s steady solar wind solution}, volume = {985}, year = {2025}, }
• (2025). Denoising diffusion probabilistic model for realistic and fast generated euclid-like data for weak lensing analysis. ApJ, 985(1), 2. (www)

  @article{ , abstract = {Understanding and mitigating measurement systematics in weak lensing (WL) analysis requires large data sets of realistic galaxies with diverse morphologies and colors. Missions like Euclid, the Nancy Roman Space Telescope, and Vera C. Rubin Observatory's Legacy Survey of Space and Time will provide unprecedented statistical power and control over systematic uncertainties. Achieving the stringent shear measurement requirement of ∣ m ∣ < 10 −3 demands analyzing 10 9 galaxies. Accurately modeling galaxy morphology is crucial, as it is shaped by complex astrophysical processes that are not yet fully understood. Subtle deviations in shape and structural parameters can introduce biases in shear calibration. The interplay between bulges, disks, star formation, and mergers contributes to morphological diversity, requiring simulations that faithfully reproduce these features to avoid systematics in shear measurements. Generating such a large and realistic data set efficiently is feasible using advanced generative models like denoising diffusion probabilistic models. In this work, we extend Hubble Space Telescope (HST) data across Euclid's broad optical band using the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey and develop a generative AI tool to produce realistic Euclid-like galaxies while preserving morphological details. We validate our tool through visual inspection and quantitative analysis of galaxy parameters, demonstrating its capability to simulate realistic Euclid galaxy images, which will address WL challenges and enhance calibration for current and future cosmological missions.}, archive = {J_ApJ}, author = {Diana Scognamiglio and Jake H. Lee and Eric Huff and Sergi R. Hildebrandt and Shoubaneh Hemmati}, doi = {10.3847/1538-4357/adcec4}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {2}, shortjournal = {The Astrophys. J.}, title = {Denoising diffusion probabilistic model for realistic and fast generated euclid-like data for weak lensing analysis}, volume = {985}, year = {2025}, }
• (2025). Comparison of equations of state for neutron stars with first-order phase transitions: A qualitative study. ApJ, 985(1), 1. (www)

  @article{ , abstract = {The equation of state is fundamental in describing matter under the extreme conditions characteristic of neutron stars and is central to advancing our understanding of dense matter physics. A critical challenge, however, lies in accurately modeling first-order phase transitions while ensuring thermodynamic consistency and aligning with astrophysical observations. This study explores two frameworks for constructing equations of states with first-order phase transitions: the polytropic interpolation method and the randomized speed-of-sound interpolation approach. It is found that the mass–radius relation and pressure versus energy density relation are blind toward the thermodynamic consistency check. The polytropic interpolation method can exhibit discontinuities in the chemical potential for first-order phase transition, raising concerns regarding potential causality violations and thermodynamic inconsistencies. In contrast, the speed of sound interpolation approach ensures continuity in the chemical potential, offering a more thermodynamically consistent and reliable framework. Moreover, the sound speed method effectively captures the softer segment of the mass–radius spectrum, having an early phase transition, a capability not achieved by the consistent piecewise-polytropic approach due to its monotonic stiffness constraints. The speed of sound definition involving number density and chemical potential reveals the thermodynamic inconsistency, making it a more consistent and robust definition. The sound speed interpolation method also generated a sufficient number of twins, which the piecewise method failed. These findings underscore the importance of thermodynamic consistency in the equation of state construction and highlight the advantages of the randomized speed-of-sound method for modeling phase transitions in dense matter.}, archive = {J_ApJ}, author = {Anshuman Verma and Asim Kumar Saha and Ritam Mallick}, doi = {10.3847/1538-4357/adcee0}, journal = {The Astrophysical Journal}, month = {5}, number = {1}, pages = {1}, shortjournal = {The Astrophys. J.}, title = {Comparison of equations of state for neutron stars with first-order phase transitions: A qualitative study}, volume = {985}, year = {2025}, }
• (2025). Erratum: “Testing CCC+TL cosmology with observed baryon acoustic oscillation features” (2024, ApJ, 964, 55). ApJ, 984(2), 202. (www)

  @article{ , archive = {J_ApJ}, author = {Rajendra P. Gupta}, doi = {10.3847/1538-4357/adccbd}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {202}, shortjournal = {The Astrophys. J.}, title = {Erratum: “Testing CCC+TL cosmology with observed baryon acoustic oscillation features” (2024, ApJ, 964, 55)}, volume = {984}, year = {2025}, }
• (2025). Erratum: “Solar wind driven from GONG magnetograms in the last solar cycle” (2024, ApJ, 965, 1). ApJ, 984(2), 201. (www)

  @article{ , archive = {J_ApJ}, author = {Zhenguang Huang and Gábor Tóth and Nishtha Sachdeva and Bart van der Holst}, doi = {10.3847/1538-4357/adcb41}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {201}, shortjournal = {The Astrophys. J.}, title = {Erratum: “Solar wind driven from GONG magnetograms in the last solar cycle” (2024, ApJ, 965, 1)}, volume = {984}, year = {2025}, }
• (2025). Exploring nuclear forces with pulsar glitch observations. ApJ, 984(2), 200. (www)

  @article{ , abstract = {We connect nuclear forces to one of the most notable irregular behaviors observed in pulsars, already detected in approximately 6% of known pulsars, with increasingly accurate data expected from upcoming high-precision timing instruments both on the ground and in space. Built on Shang & Li, we conduct a case study on the 2000 glitch of the Vela pulsar. For our purpose, we adopt the relativistic mean field (RMF) model as the theoretical many-body framework to describe nuclear systems. We refit three representative RMF parameter sets (DD-ME2, PKDD, and NL3), considering the uncertainties in nuclear matter saturation properties. Utilizing the resulting star structure, composition, and nucleon properties in the medium obtained in a consistent manner, we calculate the pinning energy of the superfluid vortex in the nuclear lattice in the inner crust. This leads to the evolution of an associated pinning force that acts on the vortex, which can be confronted with the observed glitch amplitude and short time relaxation in the 2000 Vela glitch event, following the snowplow model of the pulsar glitch. We discuss how the vortex configuration and pinning properties depend on the nuclear parameters and find an interesting and dominant role of the nuclear symmetry energy slope in pinning strength.}, archive = {J_ApJ}, author = {Zhonghao Tu and Ang Li}, doi = {10.3847/1538-4357/adc80e}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {200}, shortjournal = {The Astrophys. J.}, title = {Exploring nuclear forces with pulsar glitch observations}, volume = {984}, year = {2025}, }
• (2025). SNR g54.1+0.3, a PeVatron candidate unveiled by LHAASO. ApJ, 984(2), 199. (www)

  @article{ , abstract = {Recently, the LHAASO Collaboration reported the first very-high-energy gamma-ray catalog, containing 90 TeV sources. Among these sources, 1LHAASO J1929+1846u is located 0 \mathop{.}\limits^{\unicode{x000b0}} 3 west of SNR G54.1+0.3 and also lies within a  +53 km s −1 cloud (the Western Cloud). Moreover, one of the IceCube track-type high-energy starting events is found around 1 \mathop{.}\limits^{\unicode{x000b0}} 3 north of 1LHAASO J1929+1846u, which may serve as strong evidence for the hadronic origin of this TeV source. SNR G54.1+0.3 is a young supernova remnant (SNR), with a powerful pulsar wind nebula (PWN) inside. Its X-ray radiation from the PWN and the SNR shell can be clearly identified. The radio emission from the PWN region is also given. However, given the angular resolution of gamma-ray experiments, the entire SNR region is viewed as a point source by the Fermi Large Area Telescope, High Energy Stereoscopic System, and VERITAS. In this work, we explore a hybrid scenario where SNR G54.1+0.3 is indeed associated with the Western Cloud, and we derive the multiwavelength emissions from the PWN, the SNR shell, and the Western Cloud, separately. Our model can explain the observations well, indicating that SNR G54.1+0.3 might be an excellent candidate of the Galactic PeVatron and neutrino source.}, archive = {J_ApJ}, author = {Yihan Shi and Yudong Cui and Lili Yang}, doi = {10.3847/1538-4357/adc9a7}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {199}, shortjournal = {The Astrophys. J.}, title = {SNR g54.1+0.3, a PeVatron candidate unveiled by LHAASO}, volume = {984}, year = {2025}, }
• (2025). A parametric study of solar wind properties and composition using fluid and kinetic solar wind models. ApJ, 984(2), 198. (www)

  @article{ , abstract = {The physical processes in the solar corona that shape the solar wind remain an active research topic. Modeling efforts have shown that energy and plasma exchanges near the transition region play a crucial role in modulating solar wind properties. Although these regions cannot be measured in situ, plasma parameters can be inferred from coronal spectroscopy and ionization states of heavy ions, which remain unchanged as they escape the corona. We introduce a new solar wind model extending from the chromosphere to the inner heliosphere, capturing thermodynamic coupling across atmospheric layers. By including neutral and charged particle interactions, we model the transport and ionization processes of the gas through the transition region and corona and into the solar wind. Instead of explicitly modeling coronal heating, we link its spatial distribution to large-scale magnetic field properties. Our results confirm that energy deposition strongly affects wind properties through key mechanisms involving chromospheric evaporation, thermal expansion, and magnetic flux expansion. For sources near active regions, the model predicts significant solar wind acceleration, with plasma outflows comparable to those inferred from coronal spectroscopy. For winds from large coronal holes, the model reproduces the observed anticorrelation between charge state and wind speed. However, the predicted charge state ratios are overall lower than observed. Inclusion of a population of energetic electrons enhances both heavy ion charge states and solar wind acceleration, improving agreement with observations.}, archive = {J_ApJ}, author = {Paul Lomazzi and Alexis P. Rouillard and Michael A. Lavarra and Nicolas Poirier and Pierre-Louis Blelly and Jean-Baptiste Dakeyo and Viviane Pierrard and Victor Réville and Christian Vocks and Simon Thomas}, doi = {10.3847/1538-4357/adc2f6}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {198}, shortjournal = {The Astrophys. J.}, title = {A parametric study of solar wind properties and composition using fluid and kinetic solar wind models}, volume = {984}, year = {2025}, }
• (2025). Nucleosynthesis conditions in outflows of white dwarfs collapsing to neutron stars. ApJ, 984(2), 197. (www)

  @article{ , abstract = {An accretion-induced collapse (AIC) or merger-induced collapse (MIC) of white dwarfs (WDs) in binary systems is an interesting path to neutron star (NS) and magnetar formation, alternative to stellar core-collapse and NS mergers. Such events could add a population of compact remnants in globular clusters; they are expected to produce yet unidentified electromagnetic transients including gamma-ray and radio bursts, and to act as sources of transiron elements, neutrinos, and gravitational waves. Here, we present the first long-term (≳5 s postbounce) hydrodynamical simulations in axisymmetry (2D), using an energy- and velocity-dependent three-flavor neutrino transport based on a two-moment scheme. Our set of six models includes initial WD configurations for different masses, central densities, rotation rates, and angular momentum profiles. Our simulations demonstrate that rotation plays a crucial role for the protoneutron star (PNS) evolution and ejecta properties. We find early neutron-rich ejecta and an increasingly proton-rich neutrino-driven wind at later times in a nonrotating model, in agreement with electron-capture supernova models. In contrast to that and different from previous results, our rotating models eject proton-rich material initially and increasingly more neutron-rich matter as time advances, because an extended accretion torus forms around the PNS and feeds neutrino-driven bipolar outflows for many seconds. AIC and MIC events are thus potential sites of r -process element production, which may imply constraints on their occurrence rates. Finally, our simulations neglect the effects of triaxial deformation and magnetic fields, yet they provide valuable reference cases for comparison with future long-term magnetohydrodynamic and 3D AIC studies.}, archive = {J_ApJ}, author = {Eirini Batziou and Robert Glas and H.-Thomas Janka and Jakob Ehring and Ernazar Abdikamalov and Oliver Just}, doi = {10.3847/1538-4357/adc300}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {197}, shortjournal = {The Astrophys. J.}, title = {Nucleosynthesis conditions in outflows of white dwarfs collapsing to neutron stars}, volume = {984}, year = {2025}, }
• (2025). Late-time HST and JWST observations of GRB 221009A: Evidence for a break in the light curve at 50 days. ApJ, 984(2), 196. (www)

  @article{ , abstract = {GRB 221009A is one of the brightest transients ever observed, with the highest peak gamma-ray flux for a gamma-ray burst (GRB). A Type Ic-BL supernova (SN), SN 2022xiw, was definitively detected in late-time JWST spectroscopy ( t = 195 days, observer frame). However, photometric studies have found SN 2022xiw to be less luminous (10%−70%) than the canonical GRB-SN, SN 1998bw. We present late-time Hubble Space Telescope (HST)/WFC3 and JWST/NIRCam imaging of the afterglow and host galaxy of GRB 221009A at t ∼185, 277, and 345 days post-trigger. Our joint archival ground, HST, and JWST light-curve fits show strong support for a break in the light-curve decay slope at t = 50 ± 10 days (observer frame) and a SN at <1.5 × the optical/near-IR flux of SN 1998bw. This break is consistent with an interpretation as a jet break when requiring slow-cooling electrons in a wind medium with an electron energy spectral index p > 2 and ν m < ν c . Our light curves and joint HST/JWST spectral energy distribution (SED) also show evidence for the late-time emergence of a bluer component in addition to the fading afterglow and SN. We find consistency with the interpretations that this source is either a young, massive, low-metallicity star cluster or a scattered-light echo of the afterglow with a SED shape of f ν ∝ ν 2.0±1.0 .}, archive = {J_ApJ}, author = {Huei Sears and Ryan Chornock and Peter K. Blanchard and Raffaella Margutti and V. Ashley Villar and Justin Pierel and Patrick J. Vallely and Kate D. Alexander and Edo Berger and Tarraneh Eftekhari and Wynn V. Jacobson-Galán and Tanmoy Laskar and Natalie LeBaron and Brian D. Metzger and Dan Milisavljevic}, doi = {10.3847/1538-4357/adc306}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {196}, shortjournal = {The Astrophys. J.}, title = {Late-time HST and JWST observations of GRB 221009A: Evidence for a break in the light curve at 50 days}, volume = {984}, year = {2025}, }
• (2025). SF-R you sure? the conflicting role of star formation rates in constraining the evolution of milky way analogs in cosmological simulations. ApJ, 984(2), 195. (www)

  @article{ , abstract = {Milky Way analogs (MWAs) have long been studied by astronomers to place our Galaxy within an extragalactic context. With the power of cosmological simulations, we are now able to not only characterize MWAs today, but also watch as they evolve through cosmic time. We use the Evolution and Assembly of GaLaxies and their Environments (EAGLE) and Illustris The Next Generation (IllustrisTNG) simulations to study a group of MWAs defined by their stellar mass (SM) and star formation rate (SFR). We trace these galaxies back along their evolution to investigate the star-forming and mass assembly tracks taken by a galaxy to become an MWA today in light of these chosen parameters. We also take mock-observations of "MWAs" at z > 0 and trace them forward in time to determine if galaxies that looked similar to the Milky Way earlier in their evolution still look like the Milky Way today, thus quantifying a selection efficiency that could inform future observational studies of MWAs. We find that most galaxies with Milky Way–SM follow a similar evolution regardless of present-day SFR, although MWAs in IllustrisTNG generally have not quenched, leading to star formation histories that produce "too-blue" galaxies today. Additionally, we find contamination by MWA-"imposters" in our mock-observations, with low selection efficiency at high redshift due to the tight constraint requiring convergence to the Milky Way's present-day SFR. Our work suggests present-day SM may suffice as a stand-alone selection parameter and helps to clarify how MWAs should be selected, and thus will be an important reference for future studies of both simulated and observed MWAs.}, archive = {J_ApJ}, author = {Alicia M. Savelli and Joshua S. Speagle and J. Ted Mackereth and Norman Murray and Kartheik G. Iyer}, doi = {10.3847/1538-4357/adc38c}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {195}, shortjournal = {The Astrophys. J.}, title = {SF-R you sure? the conflicting role of star formation rates in constraining the evolution of milky way analogs in cosmological simulations}, volume = {984}, year = {2025}, }
• (2025). LAMOST young stellar objects. i. spectroscopically identifying and characterizing M-type YSOs. ApJ, 984(2), 194. (www)

  @article{ , abstract = {This study utilized Large sky Area Multi-Object fiber Spectroscopic Telescope (LAMOST) low-resolution spectra to identify M-type young stellar objects (YSOs) and characterize their accretion signatures. We measured characteristic features, including hydrogen Balmer, Li i , He i , Na i , and Ca ii lines, as well as molecular absorption bands such as CaH. These features were evaluated for their potential to distinguish between different classes of M-type stars. In addition to the commonly used H α emission and Li i λ 6708 absorption, other features such as He i , Na i , Ca ii HK and infrared triplet (IRT) lines, and CN, CaH, and VO bands also show potential for identifying YSOs from M-type dwarfs and giants. Based on key red-band features, we identified over 8500 M-type YSO candidates from the LAMOST DR8 archive using the random forest technique, with over 2300 of them likely being classical T Tauri stars (CTTSs). By incorporating Gaia astrometry, Two Micron All Sky Survey photometry, and extinction from 3D dust maps, we estimated the basic properties (such as age and mass) of the YSO candidates based on parsec models. We also estimated the mass accretion rates of the CTTS candidates using H α emission. The derived accretion rates show a dependence on age and mass similar to that described in previous studies. Significant scatter in mass accretion rates exists even among stars with a similar age and mass, which may be partly attributed to variations in H α emission and the veiling.}, archive = {J_ApJ}, author = {Xiang-Song Fang and Jian-Rong Shi and Ming-Yi Ding and Zi-Huang Cao}, doi = {10.3847/1538-4357/adc394}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {194}, shortjournal = {The Astrophys. J.}, title = {LAMOST young stellar objects. i. spectroscopically identifying and characterizing M-type YSOs}, volume = {984}, year = {2025}, }
• (2025). Photometric objects around cosmic webs (PAC). VII. disentangling mass and environment quenching with the aid of Galaxy–Halo connection in simulations. ApJ, 984(2), 193. (www)

  @article{ , abstract = {Star formation quenching in galaxies plays a crucial role in galaxy evolution and is believed to be driven primarily by galaxy mass and environment. However, disentangling these effects is difficult because galaxy mass and environment are strongly correlated. In Paper V, we addressed this challenge using the Photometric Objects Around Cosmic Webs method, which integrates spectroscopic and deep photometric surveys. This approach enabled us to measure the excess surface density {\bar{n}}_{2}{w}_{{\rm{p}}}({r}_{{\rm{p}}}) of blue and red galaxies surrounding massive central galaxies down to 10 9.0 M ⊙ . Despite this, fully separating mass and environmental effects remains challenging due to the difficulty in identifying a complete sample of low-mass central galaxies in redshift space. To overcome this, we derive the average quenched fraction of central galaxies, {\bar{f}}_{{\rm{q}}}^{{\rm{cen}}}({M}_{* }) , by combining the reconstructed 3D quenched fraction distribution {f}_{{\rm{q}}}^{{\rm{sat}}}(r;{M}_{* ,{\rm{cen}}},{M}_{* ,{\rm{sat}}}) , the stellar mass-halo mass relation in simulations, and the observed total quenched fraction, {\bar{f}}_{{\rm{q}}}^{{\rm{all}}}({M}_{* }) . With {\bar{f}}_{{\rm{q}}}^{{\rm{cen}}}({M}_{* }) , {f}_{{\rm{q}}}^{{\rm{sat}}}(r;{M}_{* ,{\rm{cen}}},{M}_{* ,{\rm{sat}}}) and the galaxy–halo connection, we assign a quenched probability to each (sub)halo and analyze galaxy quenching comprehensively. Our findings indicate that mass quenching dominates, with the mass-quenched fraction increasing from 0.3 to 0.87 across the stellar mass range [10 9.5 , 10 11.0 ] M ⊙ , while environmental quenching decreases from 0.17 to 0.03. Furthermore, more massive host halos are more effective at quenching their satellite galaxies, whereas satellite stellar mass has a minimal impact on environmental quenching. Within the studied stellar mass range, TNG300-1 exhibits lower mass-quenching efficiency but higher environmental-quenching compared to observations.}, archive = {J_ApJ}, author = {Yun Zheng and Kun Xu and Donghai Zhao and Y. P. Jing and Hongyu Gao and Xiaolin Luo and Ming Li}, doi = {10.3847/1538-4357/adc39a}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {193}, shortjournal = {The Astrophys. J.}, title = {Photometric objects around cosmic webs (PAC). VII. disentangling mass and environment quenching with the aid of Galaxy–Halo connection in simulations}, volume = {984}, year = {2025}, }
• (2025). On the external inverse compton scattering off the prompt emission in GRB 221009A. ApJ, 984(2), 192. (www)

  @article{ , abstract = {The temporal evolution of the TeV emission of GRB 221009A displays a smooth transition from an initial rapid rise to a slower rise and eventually a decay phase. The smooth light curve suggests an afterglow origin of the TeV emission. The temporal overlap between the prompt keV–MeV emission and the early TeV afterglow indicates that external inverse Compton (EIC) scattering between the prompt keV–MeV photons and the afterglow electrons is inevitable. Since the energy density of the prompt emission is much higher than that of the afterglow during the early phase, the EIC process dominates the cooling of afterglow electrons. The EIC scattering rate is influenced by the anisotropy of the seed photon field, which depends on the radius of the internal dissipation ( R dis ), where the prompt emission is produced, and that of the external shock ( R ext ), where the afterglow emission is produced. We investigate the EIC process for different values of R dis / R ext and find that the EIC scattering rate can differ by a factor of ∼2 accordingly. For GRB 221009A, the EIC emission dominates during the early rising phase of the TeV afterglow. It then transitions to a phase dominated by the synchrotron self-Compton emission as the intensity of the prompt emission decreases. Additionally, we investigate the effect of γγ absorption in the TeV afterglow by prompt MeV photons and find it insufficient to explain the early rapid rise in the TeV afterglow.}, archive = {J_ApJ}, author = {Cui-Yuan Dai and Jian-He Zheng and Xiao-Hong Zhao and Ruo-Yu Liu and Xiang-Yu Wang}, doi = {10.3847/1538-4357/adc442}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {192}, shortjournal = {The Astrophys. J.}, title = {On the external inverse compton scattering off the prompt emission in GRB 221009A}, volume = {984}, year = {2025}, }
• (2025). Cloud properties in simulated galactic winds. ApJ, 984(2), 191. (www)

  @article{ , abstract = {In this work, we investigate the properties of a population of cool clouds in simulated galaxy outflows. Using data from the Cholla Galactic OutfLow Simulations (or CGOLS) isolated galaxy simulations, we generate catalogs of ∼10 5 clouds. We describe the impact of two different supernova feedback models—a centrally concentrated starburst and disk-wide distributed star formation—on the resulting cloud population. In both cases we find that the mass distribution function dN / dM ∝ M −2 , in good agreement with model predictions of turbulent fragmentation. We explore how cloud properties change with distance from the galaxy and find no qualitative distinction between the two feedback modes, although significant quantitative differences exist in attributes such as the total number of clouds, their densities, etc. We further show that both internal cloud velocities and cloud–cloud relative velocities are described well by properties of turbulent motion, despite significant bulk radial velocities. Finally, we investigate the distribution of cloud sizes in the context of recent theoretical arguments about cloud survival in winds. We find that the proposed cloud survival criteria are a good predictor of cloud survival, in both the case where clouds are primarily destroyed and the case where cloud growth occurs in the outflow.}, archive = {J_ApJ}, author = {Orlando Warren and Evan E. Schneider and S. Alwin Mao and Matthew W. Abruzzo}, doi = {10.3847/1538-4357/adc44c}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {191}, shortjournal = {The Astrophys. J.}, title = {Cloud properties in simulated galactic winds}, volume = {984}, year = {2025}, }
• (2025). X-raying CAMELS: Constraining baryonic feedback in the circumgalactic medium with the CAMELS simulations and eRASS X-ray observations. ApJ, 984(2), 190. (www)

  @article{ , abstract = {The circumgalactic medium (CGM) around massive galaxies plays a crucial role in regulating star formation and feedback. Using the Cosmology and Astrophysics with MachinE Learning Simulations (CAMELS) suite, we develop emulators for the X-ray surface brightness profile and the X-ray luminosity–stellar mass scaling relation, to investigate how stellar and active galactic nucleus (AGN) feedback shape the X-ray properties of the hot CGM. Our analysis shows that at CGM scales (10 12 ≲ M halo / M ⊙ ≲ 10 13 , 10 ≲ r kpc −1 ≲ 400), stellar feedback more significantly impacts the X-ray properties than AGN feedback within the parameters studied. Comparing the emulators to recent eROSITA All Sky Survey (eRASS) observations, it is found that stronger feedback than is currently implemented in the IllustrisTNG, SIMBA, and Astrid simulations is required to match the observed CGM properties. However, adopting these enhanced feedback parameters causes deviations in the stellar mass–halo mass relations from observational constraints below the group-mass scale. This tension suggests possible unaccounted-for systematics in X-ray CGM observations or inadequacies in the feedback models of cosmological simulations.}, archive = {J_ApJ}, author = {Erwin T. Lau and Daisuke Nagai and Ákos Bogdán and Isabel Medlock and Benjamin D. Oppenheimer and Nicholas Battaglia and Daniel Anglés-Alcázar and Shy Genel and Yueying Ni and Francisco Villaescusa-Navarro}, doi = {10.3847/1538-4357/adc450}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {190}, shortjournal = {The Astrophys. J.}, title = {X-raying CAMELS: Constraining baryonic feedback in the circumgalactic medium with the CAMELS simulations and eRASS X-ray observations}, volume = {984}, year = {2025}, }
• (2025). Flipping of the tidal tails of the ophiuchus stream due to the decelerating galactic bar. ApJ, 984(2), 189. (www)

  @article{ , abstract = {The Ophiuchus stellar stream presents a puzzle due to its complicated morphology, with a substructure perpendicular to the main track (spur), a broadened tail (fanning), and a shorter than expected angular extent given its old stellar population and short orbital period. The location of the stream approaches the Galactic center, implying a possible connection between its orbit and its unusual morphology. Here we demonstrate that the morphology of Ophiuchus can be attributed to its interaction with the decelerating Galactic bar, which leads to the flipping or transposition of its tidal tails. The short length of the stream is the result of stars stripped in the ancient past still remaining concentrated, and the spur, as well as the fanning, are composed of either leading or trailing tails built up of stars released at different time intervals. Our new spectroscopic data, obtained as part of the Southern Stellar Stream Spectroscopic Survey, and modeling of Ophiuchus indicate that, in the presence of the bar, an initial leading tail can be redistributed to the trailing side and vice versa, and the morphology of a stream can be reshaped. This result confirms that the Galactic bar plays a vital role in reconstructing the orbital behavior of streams passing close to the central region of the Milky Way.}, archive = {J_ApJ}, author = {Yong Yang and Geraint F. Lewis and Denis Erkal and Ting S. Li and Andrew P. Li and Sarah L. Martell and Lara R. Cullinane and Guilherme Limberg and Daniel B. Zucker and Joss Bland-Hawthorn and Andrew B. Pace and Gary S. Da Costa and Alexander P. Ji and Sergey E. Koposov and Kyler Kuehn and Nora Shipp and Miles Pearson and Sam A. Usman and S5 Collaboration}, doi = {10.3847/1538-4357/adc57c}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {189}, shortjournal = {The Astrophys. J.}, title = {Flipping of the tidal tails of the ophiuchus stream due to the decelerating galactic bar}, volume = {984}, year = {2025}, }
• (2025). Exploring the relationship between stellar mass, metallicity, and star formation rate at z ∼ 2.3 in KBSS-MOSFIRE. ApJ, 984(2), 188. (www)

  @article{ , abstract = {The metal enrichment of a galaxy is determined by the cycle of baryons in outflows, inflows, and star formation. The relative contribution and timescale of each process sets the relationship between stellar mass, metallicity, and the star formation rate (SFR). In the local Universe, galaxies evolve in an equilibrium state where the timescales on which SFR and metallicity vary are comparable, and they define a surface in mass–metallicity–SFR space known as the fundamental metallicity relation (FMR). However, high-redshift observations suggest that this state of equilibrium may not persist throughout cosmic time. Using galaxies from the Keck Baryonic Structure Survey (KBSS) observed with MOSFIRE, we explore the relationship between stellar mass, gas-phase oxygen abundance, and SFR at z ∼ 2.3. Across multiple strong-line calibrations and SFR calculation methods, KBSS galaxies are inconsistent with the locally defined FMR. We use both parametric and nonparametric methods of exploring a mass–metallicity–SFR relation. When using a parametric approach, we find no significant reduction mass–metallicity relation scatter when folding in SFR as a third parameter, although a nonparametric approach reveals that there could be a weak, redshift-dependent anticorrelation between residual gas-phase oxygen abundance and SFR. Injection-recovery tests show that a significant reduction in scatter requires a stronger anticorrelation between SFR and residual metallicity. Our results suggest that the local FMR may not persist to z ∼ 2.3, implying that z ∼ 2.3 galaxies at this redshift may not be in the equilibrium state described by the FMR and are more similar to higher-redshift galaxies.}, archive = {J_ApJ}, author = {Nathalie A. Korhonen Cuestas and Allison L. Strom and Tim B. Miller and Charles C. Steidel and Ryan F. Trainor and Gwen C. Rudie and Evan Haze Nuñez}, doi = {10.3847/1538-4357/adc5f7}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {188}, shortjournal = {The Astrophys. J.}, title = {Exploring the relationship between stellar mass, metallicity, and star formation rate at z ∼ 2.3 in KBSS-MOSFIRE}, volume = {984}, year = {2025}, }
• (2025). Irradiated atmospheres. III. radiative-convective-mixing equilibrium for nongray picket-fence model. ApJ, 984(2), 187. (www)

  @article{ , abstract = {The nongray picket-fence model predicts more accurately the temperatures in low-density regions compared to semigray models. This study investigates how the vertical-mixing and convection fluxes modify the picket-fence model. The usual radiative-convective-equilibrium is now extended to radiative-convective-mixing-equilibrium. The temperature profile, characterized by an increase with pressure in the upper region and an inversion in the lower, is influenced by Rosseland opacity, spectral bands, and chemical composition. The atmosphere consists of five distinct layers: a pseudo-adiabatic zone shaped by mixing flux, two convective layers driven by convective flux with a smaller adiabatic gradient, and two radiative layers. In scenarios with lower Rosseland opacity, vertical mixing significantly reduces the width of temperature inversion, counteracting the cooling effect of the convective layers and driving the deep convective layer inward. The convective flux lowers the upper temperature and expands the upper convective layer. In the low-Rosseland-opacity five-band model, these fluxes significantly cool the midatmosphere when temperature increases with pressure, enlarging the pseudo-adiabatic region. Without TiO/VO, the pseudo-adiabatic region shrinks, indicating that TiO/VO enhances the mixing effect. Moreover, less mixing intensity is essential to maintain a stable five-layer structure. Therefore, future studies of chemical equilibrium with multifrequency atmospheric opacity should clearly define the constraints on vertical mixing.}, archive = {J_ApJ}, author = {Wei Zhong and Zhen-Tai Zhang and Bo Ma and Xianyu Tan and Dong-dong Ni and Cong Yu}, doi = {10.3847/1538-4357/adc68f}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {187}, shortjournal = {The Astrophys. J.}, title = {Irradiated atmospheres. III. radiative-convective-mixing equilibrium for nongray picket-fence model}, volume = {984}, year = {2025}, }
• (2025). Analyzing the morphology of late-phase stellar flares from G-, K-, and M-type stars. ApJ, 984(2), 186. (www)

  @article{ , abstract = {Stellar flares occasionally present a peak-bump light-curve morphology, consisting of an initial impulsive phase followed by a gradual late phase. Analyzing this specific morphology can uncover the underlying physics of stellar flare dynamics, particularly the plasma heating–evaporation–condensation process. While previous studies have mainly examined peak-bump occurrences on M dwarfs, this report extends the investigation to G-, K-, and M-type stars. We utilize the flare catalog published by J. Crowley et al., encompassing 12,597 flares, detected by using Transiting Exoplanet Survey Satellite (TESS) observations. Our analysis identifies 10,142 flares with discernible classical and complex morphology, of which 197 (∼1.9%) exhibit the peak-bump feature. We delve into the statistical properties of these TESS late-phase flares, noting that both the amplitude and FWHM durations of both the peaks and bumps show positive correlations across all source-star spectral types, following a power law with indices 0.69 ± 0.09 and 1.0 ± 0.15, respectively. Additionally, a negative correlation between the flare amplitude and the effective temperature of their host stars is observed. Compared to the other flares in our sample, peak-bump flares tend to have larger and longer initial peak amplitudes and FWHM durations and possess energies ranging from 10 31 to 10 36 erg.}, archive = {J_ApJ}, author = {Denise G. Yudovich and Kai E. Yang and Xudong Sun}, doi = {10.3847/1538-4357/adc695}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {186}, shortjournal = {The Astrophys. J.}, title = {Analyzing the morphology of late-phase stellar flares from G-, K-, and M-type stars}, volume = {984}, year = {2025}, }
• (2025). Destratification in the progenitor interior of the mg-rich supernova remnant N49B. ApJ, 984(2), 185. (www)

  @article{ , abstract = {Simulations of presupernova evolution suggest that intense O-shell burning can be so active that, in extreme cases, it can merge with the outer C-burning shell, changing the initial conditions for the supernova explosion. However, such violent activity in the interior of stars has been difficult to confirm from observations of stars. Here we propose that the elemental composition of O-rich ejecta in supernova remnants (SNRs) can be a tool to test for this kind of intense shell burning activity in the final stages of progenitor evolution. As an example, we discuss the origin of "Mg-rich" ejecta in the SNR N49B. A high Mg/Ne mass ratio ≳ 1 suggests that the Ne- or O-burning shell has broken into or merged with the outer shell before the collapse. Such Mg-rich (or Ne-poor) ejecta has been identified in some other SNRs, supporting the idea that some destratification process, such as a shell merger, does indeed occur in the interiors of some massive stars, although they may not be the majority. Our results suggest that X-ray observations of O-rich ejecta in core-collapse SNRs will be a unique tool to probe the shell burning activity in the stellar interior during the final weeks to days of a massive star's evolution.}, archive = {J_ApJ}, author = {Toshiki Sato and Kai Matsunaga and Ryo Sawada and Koh Takahashi and Yudai Suwa and John P. Hughes and Hiroyuki Uchida and Takuto Narita and Hideyuki Umeda}, doi = {10.3847/1538-4357/adc68d}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {185}, shortjournal = {The Astrophys. J.}, title = {Destratification in the progenitor interior of the mg-rich supernova remnant N49B}, volume = {984}, year = {2025}, }
• (2025). The origin of the gas and its low star formation efficiency in quiescent galaxies. ApJ, 984(2), 184. (www)

  @article{ , abstract = {Quiescent galaxies (QGs) typically have little cold gas to form stars. The discovery of gas-rich QGs challenges our conventional understanding of the evolutionary paths of galaxies. We take advantage of a new catalog of nearby massive galaxies with robust uniformly derived physical properties to better understand the origin of gas-rich QGs. We perform a comparative analysis of the cold interstellar medium and star formation properties of carefully matched samples of galaxies with varying degrees of star formation activity and gas richness. QGs with different gas content have virtually identical morphological type, light concentration, mass–size relation, stellar age, dark matter halo mass, and black hole activity. The only distinguishing characteristic is the environment. Gas-rich satellite QGs reside in a lower-density environment than their gas-poor counterparts, as a consequence of which they manage to retain their gas and experience a higher probability of cold-gas accretion or gas-rich mergers. The environmental densities of central QGs are similar regardless of their gas content. We suggest that the cold gas resides mainly in the outskirts of the gas-rich QGs, where bars, if present, cannot transport it inward efficiently to fuel central star formation. The prominent bulges in gas-rich QGs stabilize the cold gas from fragmentation and lead to low star formation efficiency.}, archive = {J_ApJ}, author = {Yang A. Li and Luis C. Ho and Jinyi Shangguan and Zhao-Yu Li and Yingjie Peng}, doi = {10.3847/1538-4357/adc71d}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {184}, shortjournal = {The Astrophys. J.}, title = {The origin of the gas and its low star formation efficiency in quiescent galaxies}, volume = {984}, year = {2025}, }
• (2025). Observation-based iterative map for solar cycles. i. nature of solar cycle variability. ApJ, 984(2), 183. (www)

  @article{ , abstract = {Intercycle variations in the series of 11 yr solar activity cycles have a significant impact on both the space environment and climate. Whether solar cycle variability is dominated by deterministic chaos or stochastic perturbations remains an open question. Distinguishing between the two mechanisms is crucial for predicting solar cycles. Here we reduce the solar dynamo process responsible for the solar cycle to a one-dimensional iterative map, incorporating recent advances in the observed nonlinearity and stochasticity of the cycle. We demonstrate that deterministic chaos is absent in the nonlinear system, regardless of model parameters, if the generation of the poloidal field follows an increase-then-saturate pattern as the cycle strength increases. The synthesized solar cycles generated by the iterative map exhibit a probability density function (PDF) similar to that of observed normal cycles, supporting the dominant role of stochasticity in solar cycle variability. The parameters governing nonlinearity and stochasticity profoundly influence the PDF. The iterative map provides a quick and effective tool for predicting the range, including uncertainty, of the subsequent cycle strength when an ongoing cycle amplitude is known. Due to stochasticity, a solar cycle loses almost all its original information within one or two cycles. Although the simplicity of the iterative map, the behaviors it exhibits are generic for the nonlinear system. Our results provide guidelines for analyzing solar dynamo models in terms of chaos and stochasticity, highlight the limitations in predicting the solar cycle, and motivate further refinement of observational constraints on nonlinear and stochastic processes.}, archive = {J_ApJ}, author = {Zi-Fan Wang and Jie Jiang and Jing-Xiu Wang}, doi = {10.3847/1538-4357/adc72d}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {183}, shortjournal = {The Astrophys. J.}, title = {Observation-based iterative map for solar cycles. i. nature of solar cycle variability}, volume = {984}, year = {2025}, }
• (2025). Stellar- and AGN-driven outflows in JWST galaxies at z = 3–9: More frequent, wider opening angles, and mostly bounded. ApJ, 984(2), 182. (www)

  @article{ , abstract = {We study outflows in 130 galaxies with −22 < M UV < −16 at z = 3–9 identified in JWST NIRSpec and NIRCam WFSS data taken by the ERO, CEERS, FRESCO, GLASS, and JADES programs. We identify 30 out of the 130 galaxies with broad components of FWHM ∼ 200–700 km s −1 in the emission lines of H α and [O iii ] that trace ionized outflows. Four out of the 30 outflowing galaxies are Type 1 AGN whose H α emission lines include line profile components as broad as FWHM ≳ 1000 km s −1 , while one galaxy is identified as a Type 2 AGN by high ionization emission lines. With the velocity shift and line widths of the outflow broad lines, we obtain ∼80–500 km s −1 for the outflow velocities. We find that the outflow velocities are slower than low- z galaxies with similar star formation rates, which may be explained by the low stellar masses of high- z galaxies. The outflow velocities of AGNs are large but not significantly different from the others. Interestingly, these outflow velocities are typically not high enough to escape from the galactic potentials, possibly suggesting fountain-type outflows. We estimate mass loading factors η to be 0.1–1, which are not particularly large, but comparable with those of z ∼ 1 outflows. The large fraction of galaxies with outflows (30% with high-resolution data) provides constraints on outflow parameters, suggesting a wide opening angle of ≳45° and a large duty cycle of ≳30%, which gives a picture of more frequent and spherical outflows in high- z galaxies.}, archive = {J_ApJ}, author = {Yi Xu and Masami Ouchi and Kimihiko Nakajima and Yuichi Harikane and Yuki Isobe and Yoshiaki Ono and Hiroya Umeda and Yechi Zhang}, doi = {10.3847/1538-4357/adc733}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {182}, shortjournal = {The Astrophys. J.}, title = {Stellar- and AGN-driven outflows in JWST galaxies at z = 3–9: More frequent, wider opening angles, and mostly bounded}, volume = {984}, year = {2025}, }
• (2025). The climates and thermal emission spectra of prime nearby temperate rocky exoplanet targets. ApJ, 984(2), 181. (www)

  @article{ , abstract = {Over the course of the past decade, advances in radial velocity and transit techniques have enabled the detection of rocky exoplanets in the habitable zones of nearby stars. Future observations with novel methods are required to characterize this sample of planets, especially those that are nontransiting. One proposed method is the Planetary Infrared Excess (PIE) technique, which would enable the characterization of nontransiting planets by measuring the excess IR flux from the planet relative to the star's spectral energy distribution. In this work, we predict the efficacy of future observations using the PIE technique by potential future observatories such as the MIRECLE mission concept. To do so, we conduct a broad suite of 21 general circulation model (GCM) simulations, with ExoCAM, of seven nearby habitable zone targets for three choices of atmospheric composition with varying partial pressure of CO 2 . We then construct thermal phase curves and emission spectra by post-processing our ExoCAM GCM simulations with the Planetary Spectrum Generator (PSG). We find that all cases have distinguishable carbon dioxide and water features assuming a 90° orbital inclination. Notably, we predict that CO 2 is potentially detectable at 15 μ m with MIRECLE for at least four nearby known nontransiting rocky planet candidate targets in the habitable zone: Proxima Centauri b, GJ 1061 d, GJ 1002 b, and Teegarden's Star c. Our ExoCAM GCMs and PSG post-processing demonstrate the potential to observationally characterize nearby nontransiting rocky planets and better constrain the potential for habitability in our solar neighborhood.}, archive = {J_ApJ}, author = {Tobi Hammond and Thaddeus D. Komacek and Ravi K. Kopparapu and Thomas J. Fauchez and Avi M. Mandell and Eric T. Wolf and Vincent Kofman and Stephen R. Kane and Ted M. Johnson and Anmol Desai and Giada Arney and Jaime S. Crouse}, doi = {10.3847/1538-4357/adc73b}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {181}, shortjournal = {The Astrophys. J.}, title = {The climates and thermal emission spectra of prime nearby temperate rocky exoplanet targets}, volume = {984}, year = {2025}, }
• (2025). Discovery and timing of four γ-ray millisecond pulsars. ApJ, 984(2), 180. (www)

  @article{ , abstract = {We discovered four millisecond pulsars (MSPs) in searches of 80 γ -ray sources conducted from 2015 to 2017 with the Murriyang radio telescope of the Parkes Observatory. We provide an overview of the survey and focus on the results of a follow-up pulsar timing campaign. Using Fermi Large Area Telescope data, we have detected γ -ray pulsations from all four pulsars, and by combining radio and γ -ray data, we obtain improved timing solutions. We also provide flux density distributions for the radio pulsars and flux-calibrated and phase-aligned radio and γ -ray pulse profiles. Some of the pulsars may be suitable for radio pulsar timing array experiments. PSR J0646–5455, PSR J1803–4719, and PSR J2045–6837 are in typical, nearly circular white dwarf binaries with residual eccentricities proportional to their binary periods. PSR J1833–3840 is a black widow pulsar with the longest known period, P b = 0.9 day, and a very soft radio spectrum. PSR J0646–5455 has a strong, Vela-like γ -ray pulse profile and is suitable for inclusion in the γ -ray pulsar timing array. Despite this, it is possibly one of the lowest-efficiency γ -ray MSPs known. Indeed, all four new γ -ray MSPs have lower-than-average efficiency, a potential indication of bias in earlier searches. Finally, we retrospectively evaluate the efficiency of this survey: while only four new MSPs were directly discovered, subsequent campaigns have found pulsars in a further 19 of our targets, an excellent 30% efficiency.}, archive = {J_ApJ}, author = {M. Kerr and S. Johnston and C. J. Clark and F. Camilo and E. C. Ferrara and M. T. Wolff and S. M. Ransom and S. Dai and P. S. Ray and J. E. Reynolds and J. M. Sarkissian and E. D. Barr and M. K. Kramer and B. W. Stappers}, doi = {10.3847/1538-4357/adc7a6}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {180}, shortjournal = {The Astrophys. J.}, title = {Discovery and timing of four γ-ray millisecond pulsars}, volume = {984}, year = {2025}, }
• (2025). Flux variations and torque reversals of cen X-3. ApJ, 984(2), 179. (www)

  @article{ , abstract = {Cen X-3 is an archetypical X-ray pulsar with strong flux variations and alternating torque reversals, both of which are similar to those of recently discovered pulsating ultraluminous X-ray sources. We study a low state of Cen X-3 that occurred in 2023, lasting for ∼100 days, with Chandra and Insight-HXMT observations, supplemented with MAXI and Fermi Gamma-ray Burst Monitor data. The Chandra spectrum during the eclipse of Cen X-3 in the low state is very similar to that in the high state, especially the Fe lines. The HXMT spectrum in the low state shows an enhanced Fe line, as do the MAXI data. The spin-up/spin-down trends of Cen X-3 are not affected by the low states. All these results indicate that the intrinsic emission in the low states is high, and the low states are just apparently low and are dominated by reprocessed emission. We found that the spin-up to spin-down reversals of Cen X-3 take a longer time than the spin-down to spin-up reversals, which provides a definite observation test of any possible torque-reversal models. We discuss insights from these results for understanding the pulsating ultraluminous X-ray sources.}, archive = {J_ApJ}, author = {Jiren Liu}, doi = {10.3847/1538-4357/adc7b4}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {179}, shortjournal = {The Astrophys. J.}, title = {Flux variations and torque reversals of cen X-3}, volume = {984}, year = {2025}, }
• (2025). Synchronous and asynchronous X-ray monitoring of FRB 20190520B with the chandra X-ray observatory. ApJ, 984(2), 178. (www)

  @article{ , abstract = {We report on X-ray limits on observations of FRB 20190520B during simultaneous observations with the Green Bank Telescope and the Chandra X-ray Observatory. FRB 20190520B is an outlier in the fast radio burst (FRB) population due to its excess source-local dispersion, its association with compact persistent radio emission, and its high line-of-sight magnetic field variability. One radio burst was detected during the overlapping observing time, and no X-ray emission was detected. We find line-of-sight density and burst duration limits on FRB 20190520B's X-ray luminosity, interpreting the nondetection in the context of known X-ray populations that might serve as progenitors for FRB 20190520B. We place a direct limit on the presence of a massive black hole (MBH) in this system, limiting mass and the Eddington ratio λ E to {M}_{\mathrm{BH}}\lt 4.3\times 1{0}^{3}({\lambda }_{{\rm{E}}}^{-1})\,{M}_{\odot } (in a low-density line-of-sight limit) and {M}_{\mathrm{BH}}\lt 1.8\times 1{0}^{4}({\lambda }_{{\rm{E}}}^{-1})\,{M}_{\odot } (high-density limit). These limits are both inconsistent with the scenario derived by Anna-Thomas et al. in which the FRB is viewed through a MBH wind; however, the model is still allowed if the wind luminosity has an X-ray emission fraction of less than 8%. Our observations would have been sensitive to the brightest ∼15% of the ultraluminous X-ray source (ULX) population and the brightest flares from soft gamma-ray repeaters, but the nondetection is consistent with expectations for SGR 1806-20–like flares, most ULX hypernebula models, and X-ray binaries.}, archive = {J_ApJ}, author = {Jessica Sydnor and Sarah Burke-Spolaor and Kshitij Aggarwal and Reshma Anna-Thomas and Casey J. Law and Harsha Blumer and Liam Connor}, doi = {10.3847/1538-4357/adc7fd}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {178}, shortjournal = {The Astrophys. J.}, title = {Synchronous and asynchronous X-ray monitoring of FRB 20190520B with the chandra X-ray observatory}, volume = {984}, year = {2025}, }
• (2025). FAST drift-scan survey for h i intensity mapping: Simulation on hunting h i filament with pairwise stacking. ApJ, 984(2), 177. (www)

  @article{ , abstract = {Filaments stand as pivotal structures within the cosmic web. However, direct detection of the cold gas content of the filaments remains challenging owing to its inherently low brightness temperature. With the TNG hydrodynamical simulations, we demonstrate the effectiveness of isolating faint filament H i signal from the FAST H i intensity mapping (IM) survey through pairwise stacking of galaxies, which yields an average H i filament signal amplitude of ∼0.29 μ K at z ≃ 0.1. However, our simulations reveal a nonnegligible contribution from H i -rich galaxies within or near the filaments. Particularly, the faint galaxies dominantly contribute to the extra filament H i signal. Our simulation also shows that the measurement uncertainty is produced by both thermal noise and background variation caused by brightness leakage from surrounding random galaxies. Given a fixed total observation time, a wide-field H i IM survey, which includes a large number of galaxy pairs, can simultaneously reduce thermal noise to below the filament signal level and minimize background variation to a negligible level. Through the end-to-end simulation, this work demonstrates the critical role of the galaxy pairwise stacking method in future filament H i detection, outlining a road map for filament H i detection in the next-generation H i IM surveys.}, archive = {J_ApJ}, author = {Diyang Liu and Yichao Li and Denis Tramonte and Furen Deng and Jiaxin Wang and Yougang Wang and Xin Zhang and Xuelei Chen}, doi = {10.3847/1538-4357/adc805}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {177}, shortjournal = {The Astrophys. J.}, title = {FAST drift-scan survey for h i intensity mapping: Simulation on hunting h i filament with pairwise stacking}, volume = {984}, year = {2025}, }
• (2025). Searching for R-process-enhanced stars in the LAMOST survey. II. two new r-II stars in the milky way disk. ApJ, 984(2), 176. (www)

  @article{ , abstract = {R -process-enhanced (RPE) stars are rare and typically metal-poor ([Fe/H]  < −1.0), primarily found in the Milky Way halo system and dwarf galaxies. This study reports the discovery of two relatively bright, highly RPE stars ([Eu/Fe]  >  +0.70) located in the Milky Way disk, with [Fe/H] of −0.34 and −0.80, respectively. These two stars are selected from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope medium-resolution ( R ∼ 7500) spectroscopic survey. Follow-up high-resolution ( R ∼ 25,000) observations were conducted with the High Optical Resolution Spectrograph installed on the 10.4 m Gran Telescopio Canarias. We perform the determination of elemental abundances and calculate the orbital parameters. We find that they are r -II stars with elemental abundances in agreement with the solar r -process pattern. These two objects are chemically and dynamically consistent with membership in the Galactic disk and exhibit no evidence of being part of accreted systems.}, archive = {J_ApJ}, author = {Xiao-Jin Xie and Jianrong Shi and Hong-Liang Yan and Tian-Yi Chen and Carlos Allende Prieto and Timothy C. Beers and Shi-Lun Jin and Shuai Liu and Chun-Qian Li and Ze-Ming Zhou and Ming-Yi Ding and Yao-Jia Tang}, doi = {10.3847/1538-4357/adc807}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {176}, shortjournal = {The Astrophys. J.}, title = {Searching for R-process-enhanced stars in the LAMOST survey. II. two new r-II stars in the milky way disk}, volume = {984}, year = {2025}, }
• (2025). Partially ionized gas at equilibrium powered by ultraviolet irradiation. ApJ, 984(2), 175. (www)

  @article{ , abstract = {We study the formation of a partially ionized zone behind the usual H II zone in photoionized gas for a density intermediate between ordinary H II regions and active galactic nucleus broad-line regions, and without X-rays. While Lyman continuum photons are depleted before reaching this zone, Balmer continuum photons can ionize the n = 2 hydrogen atoms as those are pumped by scattering-trapped Ly α photons. Ly α photons need to be replenished in a steady state, but fast radiative cooling at high gas temperature makes replenishment through electron collisional excitation of n = 2 inefficient. Independent of the temperature, Raman scattering of incident continuum photons on the Lyman-series damping wings injects Ly α photons in the line core and pumps the n = 2 state, which helps realize a partially ionized equilibrium at 5000–7000 K. Since the ratio between the incident radiation flux and gas density is limited by the dynamic effects of radiation pressure, significant ionization fraction is only realized at densities n H ≳ 10 7 cm −3 . A large H α /H β line ratio results from such partially ionized gas, as large Balmer line optical depths enhance the n = 3 population relative to higher n states. Partial ionization also provides the ideal condition for internally forming an intense and very broad Ly α line, which can power strong fluorescent metal emission lines observed from the Weigelt blobs of η Carinae in the Galaxy, and from a candidate young super star cluster in the Cosmic Noon Sunburst galaxy. This phenomenon may also have implications for understanding the spectra of high- z galaxies that show unusually dense ionized gas.}, archive = {J_ApJ}, author = {Liang Dai}, doi = {10.3847/1538-4357/adc811}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {175}, shortjournal = {The Astrophys. J.}, title = {Partially ionized gas at equilibrium powered by ultraviolet irradiation}, volume = {984}, year = {2025}, }
• (2025). Modeling hot, anisotropic ion beams in the solar wind motivated by the parker solar probe observations near perihelia. ApJ, 984(2), 174. (www)

  @article{ , abstract = {Recent observations of the solar wind ions by the SPAN-I instruments on board the Parker Solar Probe (PSP) spacecraft at solar perihelia (Encounters) 4 and closer find ample evidence of complex anisotropic non-Maxwellian velocity distributions that consist of core, beam, and "hammerhead" (i.e., anisotropic beam) populations. The proton core populations are anisotropic, with T ⊥ / T ∥ > 1, and the beams have super-Alfvénic speed relative to the core (we provide an example from Encounter 17). The α -particle population shows similar features to the protons. These unstable velocity distribution functions (VDFs) are associated with enhanced, right-hand (RH) and left-hand (LH) polarized ion-scale kinetic wave activity, detected by the FIELDS instrument. Motivated by PSP observations, we employ nonlinear hybrid models to investigate the evolution of the anisotropic hot-beam VDFs and model the growth and the nonlinear stage of ion kinetic instabilities in several linearly unstable cases. The models are initialized with ion VDFs motivated by the observational parameters. We find rapidly growing (in terms of proton gyroperiods) combined ion-cyclotron and magnetosonic instabilities, which produce LH and RH ion-scale wave spectra, respectively. The modeled ion VDFs in the nonlinear stage of the evolution are qualitatively in agreement with PSP observations of the anisotropic core and "hammerhead" velocity distributions, quantifying the effect of the ion kinetic instabilities on wind plasma heating close to the Sun. We conclude that the wave–particle interactions play an important role in the energy transfer between the magnetic energy (waves) and random particle motion, leading to anisotropic solar wind plasma heating.}, archive = {J_ApJ}, author = {Leon Ofman and Yogesh and Scott A. Boardsen and Parisa Mostafavi and Lan K. Jian and Viacheslav M. Sadykov and Kristopher Klein and Mihailo Martinović}, doi = {10.3847/1538-4357/adc812}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {174}, shortjournal = {The Astrophys. J.}, title = {Modeling hot, anisotropic ion beams in the solar wind motivated by the parker solar probe observations near perihelia}, volume = {984}, year = {2025}, }
• (2025). Reflection spectra of accretion disks illuminated by an off-axis corona. ApJ, 984(2), 173. (www)

  @article{ , abstract = {Relativistic reflection features in the X-ray spectra of accreting black holes are considered to be generated by the illumination of the accretion disk by the hot corona. In this work, we present a numerical method for the emission line profile and the reflection spectrum produced by an off-axis X-ray source. The X-ray source is considered as a point source, as in the lamppost scenario, except that it is located off-axis and moves at arbitrary velocity. The observed flux for the distant observer is calculated directly without priority evaluation of the emissivity on the accretion disk, which allows our model to be applicable to the point source that deviates from the axis of the black hole spins and moves with a velocity. To study the impact of the off-axis geometry on the measurement of source properties, we simulate observations for a black hole binary with NuSTAR and eXTP. We compare the simulation with the observation of the phase-resolved spectra of the low-frequency quasiperiodic oscillation observed by the Insight Hard X-ray Modulation Telescope. Due to the nonaxisymmetric illumination on the accretion disk, parameters of the model are not reproduced by the lamppost model, including the corona height, radial velocity, and the reflection fraction. On the other hand, all the model parameters are recovered through the off-axis model.}, archive = {J_ApJ}, author = {Yuan Feng and Ye-Fei Yuan and Shuang-Nan Zhang}, doi = {10.3847/1538-4357/adc8a6}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {173}, shortjournal = {The Astrophys. J.}, title = {Reflection spectra of accretion disks illuminated by an off-axis corona}, volume = {984}, year = {2025}, }
• (2025). A machine learning method for monte carlo calculations of radiative processes. ApJ, 984(2), 172. (www)

  @article{ , abstract = {Radiative processes such as synchrotron radiation and Compton scattering play an important role in astrophysics. Radiative processes are fundamentally stochastic in nature, and the best tools currently used for resolving these processes computationally are Monte Carlo (MC) methods. These methods typically draw a large number of samples from a complex distribution such as the differential cross section for electron–photon scattering, and then use these samples to compute the radiation properties such as angular distribution, spectrum, and polarization. In this work, we propose a machine learning (ML) technique for efficient sampling from arbitrary known probability distributions that can be used to accelerate MC calculation of radiative processes in astrophysical scenarios. In particular, we apply our technique to inverse Compton radiation and find that our ML method can be up to an order of magnitude faster than traditional methods currently in use.}, archive = {J_ApJ}, author = {William Charles and Alexander Y. Chen}, doi = {10.3847/1538-4357/adc8ac}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {172}, shortjournal = {The Astrophys. J.}, title = {A machine learning method for monte carlo calculations of radiative processes}, volume = {984}, year = {2025}, }
• (2025). Mitigating polarization leakage in gas pixel detectors through hybrid machine learning and analytic event reconstruction. ApJ, 984(2), 171. (www)

  @article{ , abstract = {Spatially resolved polarization measurements of extended X-ray sources are expanding our understanding of the emission mechanisms and magnetic field properties involved. Such measurements have been possible in the past few years thanks to the Imaging X-ray Polarimetry Explorer (IXPE). However, the analysis of extended sources suffers a systematic effect known as polarization leakage, which artificially affects the measured polarization signal. To address this issue, we built a hybrid reconstruction algorithm, which combines machine learning and analytic techniques to improve the reconstruction of photoelectron tracks in the Gas Pixel Detector and to significantly mitigate polarization leakage. This work presents the first application of this hybrid method to experimental data, including both calibration lab measurements and IXPE observational data. We confirmed the reliable performance of the hybrid method for both cases. Additionally, we demonstrated the algorithm's effectiveness in reducing the polarization leakage effect through the analysis of the IXPE observation of the supernova remnant G21.5-0.9. By enabling more reliable polarization measurements, this method can potentially yield deeper insights into the magnetic field structures, particle acceleration processes, and emission mechanisms at work within extended X-ray sources.}, archive = {J_ApJ}, author = {Nicoló Cibrario and Michela Negro and Raffaella Bonino and Nikita Moriakov and Luca Baldini and Niccoló Di Lalla and Alessandro Di Marco and Sergio Fabiani and Andrea Frassá and Alessio Gorgi and Fabio La Monaca and Luca Latronico and Simone Maldera and Alberto Manfreda and Fabio Muleri and Nicola Omodei and John Rankin and Carmelo Sgró and Stefano Silvestri and Paolo Soffitta and Stefano Tugliani}, doi = {10.3847/1538-4357/adc92c}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {171}, shortjournal = {The Astrophys. J.}, title = {Mitigating polarization leakage in gas pixel detectors through hybrid machine learning and analytic event reconstruction}, volume = {984}, year = {2025}, }
• (2025). An increase in the prevalence of ionized outflows in galaxies with coronal line emission: Feedback in action?. ApJ, 984(2), 170. (www)

  @article{ , abstract = {Coronal lines (CLs), which arise from collisionally excited forbidden transitions from highly ionized species, are a powerful diagnostic tool in uncovering active galactic nuclei (AGNs) and constraining their properties. However, recent optical surveys are finding that coronal lines are rarely detected in the majority of local AGNs, possibly as a result of the depletion of elements from the interstellar gas onto dust grains. Prominent CL emission may therefore only arise when dust is being destroyed in the highly ionized gas in AGNs. To explore the possibility that dust destruction may be caused by ionized gas outflows in galaxies with prominent CLs, we present the first large-scale systematic study of ionized outflows, as traced by the [O iii ] λ 5007 emission, in galaxies displaying CL emission relative to a robust control sample of non-CL-emitting galaxies. We find that (1) galaxies that display CL emission have a significantly elevated outflow incidence rate compared to their matched controls, (2) the outflow luminosity is significantly higher in the CL emitters, (3) the CL emitters have systematically lower intrinsic extinction toward the ionized gas compared with the controls, and (4) there are significant correlations between the CL luminosity and outflow velocity for the iron CLs, with similar relationships found between the CL FWHM and outflow luminosity. These observations are consistent with dust destruction in an outflowing wind from a dusty torus causing efficient CL emission.}, archive = {J_ApJ}, author = {William Matzko and Shobita Satyapal and Michael Reefe and Jeffrey McKaig and Remington O. Sexton and Sara Doan}, doi = {10.3847/1538-4357/adc92f}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {170}, shortjournal = {The Astrophys. J.}, title = {An increase in the prevalence of ionized outflows in galaxies with coronal line emission: Feedback in action?}, volume = {984}, year = {2025}, }
• (2025). Loop I/NPS morphology predictions in the ultralong-wavelength band. ApJ, 984(2), 169. (www)

  @article{ , abstract = {Loop I/North Polar Spur (NPS) is the giant arc structure above the Galactic plane observed at radio wavelengths (≲10 GHz). There has been long-standing debate about its origin. While many people believe that it consists of nearby supernova remnants (SNRs), some others consider it as a giant bubble close to the Galactic Center (GC), associated with the Fermi Bubble and the eROSITA X-ray bubble. At ultralong wavelengths (wavelength ≳10 m or frequency ≲30 MHz), particularly below ∼10 MHz, the free–free absorption of the radio signal by diffuse electrons in the interstellar medium (ISM) becomes significant, resulting in different sky morphologies from those at higher frequencies. In this paper, we develop emissivity models for the two Loop I/NPS origin scenarios, and predict the Loop I/NPS morphology at ultralong wavelengths in both scenarios, taking into account the free–free absorption effect. We find that in the SNRs model, the full Loop I/NPS will still be a bright arc, even at ∼1 MHz. In the GC model, the arc is fully visible only above ∼3 MHz. While below this frequency, it is visible only at Galactic latitudes b ≳ 30°; the b ≲ 30° part becomes invisible due to the absorption by the ISM electrons between the GC and the Sun. The upcoming space missions aiming at ultralong wavelengths, such as the Discovering Sky at the Longest wavelength and the Farside Array for Radio Science Investigations of the Dark ages and Exoplanets, can potentially distinguish these two scenario and provide decisive information about the origin of the Loop I/NPS.}, archive = {J_ApJ}, author = {Yanping Cong and Bin Yue and Yidong Xu and Furen Deng and Jiajun Zhang and Xuelei Chen}, doi = {10.3847/1538-4357/adc9a4}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {169}, shortjournal = {The Astrophys. J.}, title = {Loop I/NPS morphology predictions in the ultralong-wavelength band}, volume = {984}, year = {2025}, }
• (2025). Radiation signatures of electron acceleration in the decelerating jet of MAXI j1348-630. ApJ, 984(2), 168. (www)

  @article{ , abstract = {A discrete jet component (blob) ejection and its subsequent deceleration were observed in the 2019/2020 outburst of the low-mass X-ray binary MAXI J1348-630. A first kinematic analysis of the deceleration due to an abrupt transition from an evacuated cavity to the interstellar medium (ISM) suggested a kinetic energy exceeding 10 46 erg, surpassing estimates of the available total ejection energy. However, incorporating a transition layer with exponential density growth between the cavity and the ISM recently enabled a kinematic analysis with much more realistic energy requirements of approximately 10 44 erg. Here, we study the expected radiative signatures of electrons accelerated within the decelerating blob by introducing a model akin to the relativistic blast wave model for gamma-ray bursts, considering radiative energy losses and radiation drag, to simulate the deceleration of a relativistically moving plasmoid. This model yields snapshot spectral energy distributions and multiwavelength light curves from synchrotron and synchrotron-self-Compton emission. Notably, the synchrotron emission peaks in the X-rays, but the predicted X-ray flux is negligible compared to thermal emission from the accretion disk. The predicted radio light curve closely resembles the observed one during the jet deceleration phase following the outburst in 2019/2020.}, archive = {J_ApJ}, author = {Aishwarya Sarath and Markus Böttcher}, doi = {10.3847/1538-4357/adcac1}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {168}, shortjournal = {The Astrophys. J.}, title = {Radiation signatures of electron acceleration in the decelerating jet of MAXI j1348-630}, volume = {984}, year = {2025}, }
• (2025). Spectral features of the energy-containing range and the inertial range in fast solar wind turbulence. ApJ, 984(2), 167. (www)

  @article{ , abstract = {Power spectra of the fluctuations provide a baseline to interpret the solar wind turbulence in the magnetohydrodynamic scale. The magnetic spectra show a typical index of −1 in the low-frequency range, which is regarded as the energy-containing region. Recent studies show that it can be much shallower than 1/ f in the near-Sun solar wind, indicating that there is a dynamic origin for the 1/ f range formation. However, the nature of the energy-containing range remains unanswered. Here we investigate 97 fast solar wind intervals, each with time durations ≥2 days at 1 au observed by the Wind spacecraft from 2005 to 2018. We perform the spectral analyses and find that the spectral index in the energy-containing range is −0.78 ± 0.22 for the magnetic field and −1.49 ± 0.30 for the velocity. To compare, the spectral index in the inertial range is −1.60 ± 0.04 for the magnetic field and −1.51 ± 0.04 for the velocity. In both ranges, the indices for the magnetic field and the velocity are correlated. The cross helicity σ c grows to the saturation level before the break between the two ranges. The saturation level is correlated with the magnetic spectral index in the inertial range and the velocity spectral index in the energy-containing range. Our findings provide new clues for the origin of the energy source and help understand the evolution from the energy-containing range to the inertial range.}, archive = {J_ApJ}, author = {Honghong Wu and Shiyong Huang and Liping Yang and Jiansen He and Zhigang Yuan}, doi = {10.3847/1538-4357/adcd67}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {167}, shortjournal = {The Astrophys. J.}, title = {Spectral features of the energy-containing range and the inertial range in fast solar wind turbulence}, volume = {984}, year = {2025}, }
• (2025). Upper limits to the proper motions of JuMBO 24, a jupiter-mass binary object candidate in orion. ApJ, 984(2), 166. (www)

  @article{ , abstract = {Using JWST near-infrared data of the inner Orion Nebula, S. G. Pearson & M. J. McCaughrean detected 40 binary systems they proposed to be Jupiter-mass binary objects (JuMBOs)—although their actual nature is still in debate. Only one of the objects, JuMBO 24, was detected in the radio continuum. Here, we report on new radio continuum (10 GHz) Karl G. Jansky Very Large Array (VLA) detections of the radio counterpart to JuMBO 24, and on an unsuccessful search for 5 GHz continuum emission with the High Sensitivity Array (HSA). From our new VLA detections and adopting a distance to the region, we set an upper limit of ≃6 km s −1 to the velocity of the radio source in the plane of the sky. This upper limit favors an origin for this source similar to that of stars, that is, from a stationary contracting core. The nature of the radio emission remains uncertain, but the lack of strong variability (all VLA observations are consistent with a steady flux of ∼50 μ Jy), of detection on long HSA baselines, and of detectable circular polarization in VLA data do not favor a nonthermal origin.}, archive = {J_ApJ}, author = {Luis F. Rodríguez and Laurent Loinard and Luis A. Zapata and Gisela N. Ortiz-León}, doi = {10.3847/1538-4357/adceaa}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {166}, shortjournal = {The Astrophys. J.}, title = {Upper limits to the proper motions of JuMBO 24, a jupiter-mass binary object candidate in orion}, volume = {984}, year = {2025}, }
• (2025). Diverse dust populations in the near-sun environment characterized by PSP/ISʘIS. ApJ, 984(2), 165. (www)

  @article{ , abstract = {The Integrated Science Investigation of the Sun energetic particle instrument suite on the Parker Solar Probe is dedicated to measuring energetic ions and electrons in the near-Sun environment. It includes a half-sky-viewing time-of-flight mass spectrometer (EPI-Lo) and five high-energy silicon solid-state detector-telescopes (EPI-Hi). To 2024 August, eight of EPI-Lo's eighty separate telescope foils have experienced direct dust puncture events, most of which occurred inside 40 solar radii (0.19 au). These impacts represent the closest high-fidelity dust detections to the Sun. While there is limited information about the size/mass of each impact due to the lack of a dedicated dust instrument, we can determine the impact direction for six punctures, allowing us to partially constrain abundant dust populations in the inner zodiacal cloud. Remarkably, one of six unambiguous dust impactors was likely on a retrograde orbit, suggesting long-period cometary material may survive within 20 solar radii (0.09 au). We discuss observations in the context of highlighting multiple dust populations responsible for these events to improve our understanding of the zodiacal dust environment in the inner heliosphere ( \lesssim 1 au).}, archive = {J_ApJ}, author = {M. M. Shen and J. R. Szalay and P. Pokorný and J. G. Mitchell and M. E. Hill and D. G. Mitchell and D. J. McComas and E. R. Christian and C. M. S. Cohen and N. A. Schwadron and S. D. Bale and D. M. Malaspina}, doi = {10.3847/1538-4357/adc258}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {165}, shortjournal = {The Astrophys. J.}, title = {Diverse dust populations in the near-sun environment characterized by PSP/ISʘIS}, volume = {984}, year = {2025}, }
• (2025). Multi-height study of the chromospheric inverse evershed flow and its association with photospheric flows. ApJ, 984(2), 164. (www)

  @article{ , abstract = {We analyzed the inverse Evershed flow (IEF) around a sunspot (NOAA 13131) using line scan observations in the Fe i 6173 Å and Ca ii 8542 Å spectral lines, complemented with data products from the Solar Dynamics Observatory's Helioseismic and Magnetic Imager. Line-of-sight (LOS) velocities were obtained for different bisector levels in both spectral lines. Additionally, the Ca ii 8542 Å spectra were inverted using the Non-LTE Inversion COde using the Lorien Engine (or NICOLE) to retrieve the temperature and velocity stratification over different layers of the lower solar atmosphere. The IEF evolved dynamically in time and with height in the solar atmosphere. The flow speed associated with the IEF channels was on the order of 8 km s −1 in the upper chromosphere, which decreased in the lower layers of the atmosphere. The flow was traced to the lower chromosphere in LOS velocity maps and the upper photosphere in intensity images. The temperature enhancements associated with the IEF were up to 300 K at log τ ≈ −2 and 800 K at log τ ≈ −6 near the end point of one channel. The overall appearance of the flow along the IEF channels seems consistent with a siphon flow model. We investigated the association of the IEF with the photospheric Evershed flow, but no obvious connection was found in our analysis. We also analyzed the effect of the IEF on moving magnetic features (MMF) selected near and away from IEF channels. MMFs moved radially outward with velocities in the 0.2–1 km s −1 range, with no apparent association with the IEF.}, archive = {J_ApJ}, author = {Sandeep K. Dubey and Shibu K. Mathew and Christian Beck and Debi P. Choudhary}, doi = {10.3847/1538-4357/adc1cd}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {164}, shortjournal = {The Astrophys. J.}, title = {Multi-height study of the chromospheric inverse evershed flow and its association with photospheric flows}, volume = {984}, year = {2025}, }
• (2025). The LUNIS-AGN catalog: Trends of emission line velocity dispersion and surface brightness within the circumnuclear regions of seyfert galaxies. ApJ, 984(2), 163. (www)

  @article{ , abstract = {We present the Local Universe Near-Infrared Seyfert catalog of K- band integral field unit data of 88 nearby active galactic nuclei (AGN), curated from SINFONI/Very Large Telescope and OSIRIS/Keck archival data sets. This catalog includes both type 1 and type 2 Seyfert AGN probed down to scales of tens of parsecs with z < 0.02 and spanning over 5 orders of magnitude in L 14−195 keV AGN luminosity. As part of this catalog, we make publicly available for all galaxies the processed data cubes, a central 200 pc integrated spectrum, and two-dimensional maps of flux, velocity, and velocity dispersion for H 2 1-0 S(1) 2.1218 μ m, [Si vi ] 1.9641 μ m, and Br- γ 2.1655 μ m. The morphology and geometry of [Si vi ], a tracer of AGN outflows, are reported for the 66% of galaxies with extended emission. We utilize this large sample to probe the behavior of molecular and ionized gas, identifying trends in the properties of the circumnuclear gas (surface brightness and velocity dispersion) with fundamental AGN properties (obscuration and X-ray luminosity). While there is significant variation in circumnuclear gas characteristics across the sample, we find molecular hydrogen to be less centrally concentrated and to exhibit lower velocity dispersion relative to ionized gas. In addition, we find elevated molecular hydrogen surface brightness and decreased [Si vi ] velocity dispersion in obscured relative to unobscured AGN. The [Si vi ] and Br- γ emission scale with L 14−195 keV X-ray luminosity, which, along with the elevated velocity dispersion compared to the molecular gas, verifies an association with AGN outflow processes.}, archive = {J_ApJ}, author = {Dan Delaney and Cassidy Berger and Erin Hicks and Leonard Burtscher and David Rosario and Francisco Müller-Sánchez and Matthew Malkan}, doi = {10.3847/1538-4357/adc1cc}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {163}, shortjournal = {The Astrophys. J.}, title = {The LUNIS-AGN catalog: Trends of emission line velocity dispersion and surface brightness within the circumnuclear regions of seyfert galaxies}, volume = {984}, year = {2025}, }
• (2025). OMEGACat. v. helium enrichment in ω centauri as a function of metallicity. ApJ, 984(2), 162. (www)

  @article{ , abstract = {Constraining the helium enhancement in stars is critical for understanding the formation mechanisms of multiple populations in star clusters. However, measuring helium variations for many stars within a cluster remains observationally challenging. We use Hubble Space Telescope photometry combined with MUSE spectroscopic data for over 7200 red giant branch stars in ω Cen to measure helium differences between distinct groups of stars as a function of metallicity, separating the impact of helium enhancements from other abundance variations on the pseudo-color (chromosome) diagram. Our results show that stars at all metallicities have subpopulations with significant helium enhancement (Δ Y min ≳ 0.11). We find a rapid increase in helium enhancement across low metallicities ([Fe/H] ≃ −2.05 to [Fe/H] ≃ −1.92), with this enhancement leveling out at Δ Y = 0.15 at higher metallicities. The fraction of helium-enhanced stars steadily increases with metallicity from 10% at [Fe/H] ≃ −2.04 to over 90% at [Fe/H] ≃ −1.04. From these measurements, we calculate the total mass in helium produced over the cluster's lifetime, finding {{M}}_{{{\rm{He}}}_{{\rm{tot}}}}\sim 2.7\times 1{0}^{5}{{M}}_{\odot } . This study is the first to examine helium enhancement across the full range of metallicities in ω Cen, providing new insight into its formation history and additional constraints on enrichment mechanisms.}, archive = {J_ApJ}, author = {C. Clontz and A. C. Seth and Z. Wang and S. O. Souza and M. Häberle and M. S. Nitschai and N. Neumayer and M. Latour and A. P. Milone and A. Feldmeier-Krause and N. Kacharov and M. Libralato and A. Bellini and G. van de Ven and M. Alfaro-Cuello}, doi = {10.3847/1538-4357/adc1c5}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {162}, shortjournal = {The Astrophys. J.}, title = {OMEGACat. v. helium enrichment in ω centauri as a function of metallicity}, volume = {984}, year = {2025}, }
• (2025). The gaseous blowout of the 30 doradus starburst region in the LMC. ApJ, 984(2), 161. (www)

  @article{ , abstract = {Widespread galactic winds emanate from the Large Magellanic Cloud (LMC), with the 30 Doradus starburst region generating the fastest and most concentrated gas flows. We report on the gas distribution, kinematics, and ionization conditions of the near-side outflow along eight down-the-barrel sightlines using UV absorption-line observations from the Hubble Space Telescope's Ultraviolet Legacy Library of Young Stars as Essential Standards (ULLYSES) program for this region along with H i 21 cm observations from the Parkes Galactic All-Sky Survey (GASS) and Galactic Australian Square Kilometre Array Pathfinder (GASKAP) survey. We find that within Δ θ ≲ 1 \mathop{.}\limits^{\unicode{x000B0}} 7 from the center of 30 Doradus, the wind reaches maximum speeds of 100–150 km s −1 from the LMC's disk. The total integrated column densities of low ions (O i , Si ii , and Fe ii ) in the blueshifted wind, up to v LSR = 150 km s −1 , are highest near the center and decline radially outward. We estimate an outflow mass of M outflow, Si ii ≈ (5.7–8.6) × 10 5 M ⊙ , outflow rate of {\dot{M}}_{{\rm{outflow}}}\gtrsim 0.02{M}_{\odot }\,{\,\rm{yr}\,}^{-1} , and mass loading factor of η ≳ 0.10 within Δ θ ≲ 0 \mathop{.}\limits^{\unicode{x000B0}} 52 from the center of 30 Doradus. The observed ion ratios—together with photoionization modeling—reveal that this wind is roughly 40%–97% photoionized. The metallicities and dust depletion patterns of the high-velocity absorbers at v LSR ≈ +120 km s −1 can be explained by either a foreground Milky Way (MW) halo cloud or an outflow from the LMC. For the high ions, Si iv and C iv are broader and kinematically offset from the low ions, suggesting turbulent mixing layers existing in the wind. Finally, our hydrodynamical simulations of the Magellanic Clouds and MW system suggest that the Magellanic Corona can protect the LMC winds from the ram pressure forces exerted by the MW's halo.}, archive = {J_ApJ}, author = {Suraj Poudel and April Horton and Jo Vazquez and Kathleen A. Barger and Frances H. Cashman and Andrew J. Fox and Nicolas Lehner and Scott Lucchini and Dhanesh Krishnarao and N. M. McClure-Griffiths and Elena D’Onghia and Jason Tumlinson and Ananya Goon Tuli and Lauren Sdun and Stone Gebhart and Katherine Anthony and Bryce Cole and Jacco Th. van Loon and Julia Roman-Duval and Yik Ki Ma and Callum Lynn and Min-Young Lee and Denis Leahy}, doi = {10.3847/1538-4357/adc099}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {161}, shortjournal = {The Astrophys. J.}, title = {The gaseous blowout of the 30 doradus starburst region in the LMC}, volume = {984}, year = {2025}, }
• (2025). SN 2021hpr: A normal type ia supernova showing excess emission in the early rising phase. ApJ, 984(2), 160. (www)

  @article{ , abstract = {We present extensive optical observations of a nearby Type Ia supernova (SN Ia), SN 2021hpr, located in the spiral galaxy NGC 3147 at a distance of ∼45 Mpc. Our observations cover a phase within ∼1–2 days to ∼290 days after the explosion. SN 2021hpr is found to be a spectroscopically normal SN Ia, with an absolute B -band peak magnitude of {M}_{{\rm{\max }}}(B)\approx -19.16\pm 0.14 mag and a postpeak decline rate of Δ m 15 ( B ) =  1.0 ± 0.01 mag. Early time light curves showed a ∼7.0% excess emission compared to a homogeneously expanding fireball model, likely due to SN ejecta interacting with a companion or immediate circumstellar matter (CSM). The optical spectra of SN 2021hpr are overall similar to those of normal SNe Ia, but characterized by prominent detached high-velocity features (HVFs) of Si ii and Ca ii in the early phase. After examining a small sample of well-observed normal SNe Ia, we find that the HVFs are likely common for the subgroup with early excess emission. The association of an early bump feature with the HVFs could be attributed to density or abundance enhancement at the outer layer of the exploding star, likely as a result of interactions with companion/CSM or experiencing more complete burning. Nevertheless, the redshifted Fe ii and Ni ii lines in the nebular-phase spectra of SN 2021hpr, contrary to the blueshift trend seen in other SNe Ia showing early bump features, indicate its peculiarity in the explosion that remains to be understood.}, archive = {J_ApJ}, author = {Abdusamatjan Iskandar and Xiaofeng Wang and Ali Esamdin and Xiangyun Zeng and Craig Pellegrino and Shengyu Yan and Jialian Liu and Alexei V. Filippenko and D. Andrew Howell and Curtis McCully and Thomas G. Brink and Maokai Hu and Yi Yang and WeiKang Zheng and Guoliang Lü and Jujia Zhang and CuiYing Song and RuiFeng Huang and Rachael C. Amaro and Chunhai Bai and Kyle G. Dettman and Lluís Galbany and Daichi Hiramatsu and Bostroem K. Azalee and Koichi Itagaki and Saurabh W. Jha and Shuguo Ma and David J. Sand and Jennifer E. Andrews and Jacob Jencson and Peter Milne and Jeniveve Pearson and Manisha Shrestha and Nathan Smith and Réka Könyves-Tóth and Samuel Wyatt and Xuan Zhang and Shahidin Yaqup and Letian Wang and Mengfan Zhang}, doi = {10.3847/1538-4357/adb3a4}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {160}, shortjournal = {The Astrophys. J.}, title = {SN 2021hpr: A normal type ia supernova showing excess emission in the early rising phase}, volume = {984}, year = {2025}, }
• (2025). 3D CMZ. IV. distinguishing near versus far distances in the galactic center using spitzer and herschel. ApJ, 984(2), 159. (www)

  @article{ , abstract = {A comprehensive 3D model of the central 300 pc of the Milky Way, the Central Molecular Zone (CMZ) is of fundamental importance in understanding energy cycles in galactic nuclei, since the 3D structure influences the location and intensity of star formation, feedback, and black hole accretion. Current observational constraints are insufficient to distinguish between existing 3D models. Dust extinction is one diagnostic tool that can help determine the location of dark molecular clouds relative to the bright Galactic Center emission. By combining Herschel and Spitzer observations, we developed three new dust extinction techniques to estimate the likely near/far locations for each cloud in the CMZ. We compare our results to four geometric CMZ orbital models. Our extinction methods show good agreement with each other, and with results from spectral line absorption analysis from Walker et al. Our near/far results for CMZ clouds are inconsistent with a projected version of the Y. Sofue two-spiral-arms model, and show disagreement in position–velocity space with the S. Molinari et al. closed elliptical orbit. Our results are in reasonable agreement with the J. M. D. Kruijssen et al. open streams. We find that a simplified toy-model elliptical orbit that conserves angular momentum shows promising fits in both position–position and position–velocity space. We conclude that all current CMZ orbital models lack the complexity needed to describe the motion of gas in the CMZ, and further work is needed to construct a complex orbital model to accurately describe gas flows in the CMZ.}, archive = {J_ApJ}, author = {Dani Lipman and Cara Battersby and Daniel L. Walker and Mattia C. Sormani and John Bally and Ashley Barnes and Adam Ginsburg and Simon C. O. Glover and Jonathan D. Henshaw and H Perry Hatchfield and Katharina Immer and Ralf S. Klessen and Steven N. Longmore and Elisabeth A. C. Mills and Rowan Smith and R. G. Tress and Danya Alboslani and Qizhou Zhang}, doi = {10.3847/1538-4357/adb5ee}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {159}, shortjournal = {The Astrophys. J.}, title = {3D CMZ. IV. distinguishing near versus far distances in the galactic center using spitzer and herschel}, volume = {984}, year = {2025}, }
• (2025). 3D CMZ. III. constraining the 3D structure of the central molecular zone via molecular line emission and absorption. ApJ, 984(2), 158. (www)

  @article{ , abstract = {The Milky Way's Central Molecular Zone (CMZ) is the largest concentration of dense molecular gas in the Galaxy, the structure of which is shaped by the complex interplay between Galactic-scale dynamics and extreme physical conditions. Understanding the 3D geometry of this gas is crucial, as it determines the locations of star formation and subsequent feedback. We present a catalog of clouds in the CMZ using Herschel data. Using archival data from the APEX and MOPRA CMZ surveys, we measure averaged kinematic properties of the clouds at 1 and 3 mm. We use archival ATCA data of the H 2 CO (1 1,0 –1 1,1 ) 4.8 GHz line to search for absorption towards the clouds, and 4.85 GHz Green Bank Telescope (GBT) C -band data to measure the radio continuum emission. We measure the absorption against the continuum to provide new constraints for the line-of-sight positions of the clouds relative to the Galactic Center, and find a highly asymmetric distribution, with most clouds residing in front of the Galactic Center. The results are compared with different orbital models, and we introduce a revised toy model of a vertically oscillating closed elliptical orbit. We find that most models describe the position–position–velocity structure of the gas reasonably well, but find significant inconsistencies in all cases regarding the near versus far placement of individual clouds. Our results highlight that the CMZ is likely more complex than can be captured by these simple geometric models, along with the need for new data to provide further constraints on the true 3D structure of the CMZ.}, archive = {J_ApJ}, author = {Daniel L. Walker and Cara Battersby and Dani Lipman and Mattia C. Sormani and Adam Ginsburg and Simon C. O. Glover and Jonathan D. Henshaw and Steven N. Longmore and Ralf S. Klessen and Katharina Immer and Danya Alboslani and John Bally and Ashley Barnes and H Perry Hatchfield and Elisabeth A. C. Mills and Rowan Smith and Robin G. Tress and Qizhou Zhang}, doi = {10.3847/1538-4357/adb5ef}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {158}, shortjournal = {The Astrophys. J.}, title = {3D CMZ. III. constraining the 3D structure of the central molecular zone via molecular line emission and absorption}, volume = {984}, year = {2025}, }
• (2025). 3D CMZ. II. hierarchical structure analysis of the central molecular zone. ApJ, 984(2), 157. (www)

  @article{ , abstract = {The Central Molecular Zone (CMZ) is the way station at the heart of our Milky Way Galaxy, connecting gas flowing in from Galactic scales with the central nucleus. Key open questions remain about its 3D structure, star formation properties, and role in regulating this gas inflow. In this work, we identify a hierarchy of discrete structures in the CMZ using column density maps from Paper I (C. Battersby et al.) We calculate the physical ( N (H 2 ), T dust , mass, radius) and kinematic (HNCO, HCN, and HC 3 N moments) properties of each structure as well as their bolometric luminosities and star formation rates. We compare these properties with regions in the Milky Way disk and external galaxies. Despite the fact that the CMZ overall is well below the Gao-Solomon dense gas star formation relation (and in modest agreement with the Schmidt–Kennicutt relation), individual structures on the scale of molecular clouds generally follow these star formation relations and agree well with other Milky Way and extragalactic regions. We find that individual CMZ structures require a large external pressure ( P e / k B > 10 7−9 K cm −3 ) to be considered bound; however, simple estimates suggest that most CMZ molecular-cloud-sized structures are consistent with being in pressure-bounded virial equilibrium. We perform power-law fits to the column density probability distribution functions of the inner 100 pc, SgrB2, and the outer 100 pc of the CMZ as well as several individual molecular cloud structures and find generally steeper power-law slopes (−9 < α < −2) compared with the literature (−6 < α < −1).}, archive = {J_ApJ}, author = {Cara Battersby and Daniel L. Walker and Ashley Barnes and Adam Ginsburg and Dani Lipman and Danya Alboslani and H Perry Hatchfield and John Bally and Simon C. O. Glover and Jonathan D. Henshaw and Katharina Immer and Ralf S. Klessen and Steven N. Longmore and Elisabeth A. C. Mills and Sergio Molinari and Rowan Smith and Mattia C. Sormani and Robin G. Tress and Qizhou Zhang}, doi = {10.3847/1538-4357/adb844}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {157}, shortjournal = {The Astrophys. J.}, title = {3D CMZ. II. hierarchical structure analysis of the central molecular zone}, volume = {984}, year = {2025}, }
• (2025). 3D CMZ. i. central molecular zone overview. ApJ, 984(2), 156. (www)

  @article{ , abstract = {The Central Molecular Zone (CMZ) is the largest reservoir of dense molecular gas in the Galaxy and is heavily obscured in the optical and near-IR. We present an overview of the far-IR dust continuum, where the molecular clouds are revealed, provided by Herschel in the inner 40° (∣ l ∣ < 20°) of the Milky Way with a particular focus on the CMZ. We report a total dense gas ( N (H 2 ) > 10 23 cm −2 ) CMZ mass of \sim {2}_{-1}^{+2}\times 1{0}^{7} M ⊙ and confirm that there is a highly asymmetric distribution of dense gas, with about 70%–75% at positive longitudes. We create and publicly release complete fore/background-subtracted column density and dust temperature maps in the inner 40° (∣ l ∣ < 20°) of the Galaxy. We find that the CMZ clearly stands out as a distinct structure, with an average mass per longitude that is at least 3 × higher than the rest of the inner Galaxy contiguously from 1 \mathop{.}\limits^{\unicode{x000B0}} 8 > ℓ > −1 \mathop{.}\limits^{\unicode{x000B0}} 3. This CMZ extent is larger than previously assumed, but is consistent with constraints from velocity information. The inner Galaxy's column density peaks towards the SgrB2 complex with a value of about 2 × 10 24 cm −2 , and typical CMZ molecular clouds are about N (H 2 ) ∼ 10 23 cm −2 . Typical CMZ dust temperatures range from ∼12–35 K with relatively little variation. We identify a ridge of warm dust in the inner CMZ that potentially traces the base of the northern Galactic outflow seen with MEERKAT.}, archive = {J_ApJ}, author = {Cara Battersby and Daniel L. Walker and Ashley Barnes and Adam Ginsburg and Dani Lipman and Danya Alboslani and H Perry Hatchfield and John Bally and Simon C. O. Glover and Jonathan D. Henshaw and Katharina Immer and Ralf S. Klessen and Steven N. Longmore and Elisabeth A. C. Mills and Sergio Molinari and Rowan Smith and Mattia C. Sormani and Robin G. Tress and Qizhou Zhang}, doi = {10.3847/1538-4357/adb5f0}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {156}, shortjournal = {The Astrophys. J.}, title = {3D CMZ. i. central molecular zone overview}, volume = {984}, year = {2025}, }
• (2025). Chandra detects low-luminosity active galactic nucleus with MBH = 104–106 m⊙ in nearby (z < 0.5) dwarf and star-forming galaxies. ApJ, 984(2), 155. (www)

  @article{ , abstract = {We searched the Chandra and XMM archives for 900 Green Pea galaxies to identify signs of active galactic nuclei (AGN). Green peas are low-mass, emission-line galaxies that resemble high-redshift dwarf galaxies. From 29 observations, we detected X-rays in nine galaxies with signal-to-noise ratio > 3. These X-ray sources also show He ii and broad H α emissions, suggesting winds, though the weak correlation between their line widths implies that the He ii emission is not from super-Eddington accretors. The ratio of X-ray luminosity to star formation rate aligns with an anticorrelation with metallicity for most detected sources, pointing to ultraluminous X-ray sources as likely contributors. The X-ray emission exceeds what stellar processes can produce, supporting the existence of low-luminosity AGN. Using the broad H α emission lines, we infer black hole masses ranging from 10 4 to 10 6 M ⊙ in these sources. Since Green Peas are significant Lyman continuum leakers, these AGN may have played a role in cosmic reionization.}, archive = {J_ApJ}, author = {Mainak Singha and Julissa Sarmiento and Sangeeta Malhotra and James E. Rhoads and L. Y. Aaron Yung and Junxian Wang and Zhen-Ya Zheng and Ruqiu Lin and Keunho Kim and Jialai Kang and Santosh Harish}, doi = {10.3847/1538-4357/adb979}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {155}, shortjournal = {The Astrophys. J.}, title = {Chandra detects low-luminosity active galactic nucleus with MBH = 104–106 m⊙ in nearby (z < 0.5) dwarf and star-forming galaxies}, volume = {984}, year = {2025}, }
• (2025). Irregularly sampled time series interpolation for detailed binary evolution simulations. ApJ, 984(2), 154. (www)

  @article{ , abstract = {Modeling of large populations of binary stellar systems is an integral part of many areas of astrophysics, from radio pulsars and supernovae to X-ray binaries, gamma-ray bursts, and gravitational-wave mergers. Binary population synthesis codes that employ self-consistently the most advanced physics treatment available for stellar interiors and their evolution and are at the same time computationally tractable have started to emerge only recently. One element that is still missing from these codes is the ability to generate the complete time evolution of binaries with arbitrary initial conditions using precomputed three-dimensional grids of binary sequences. Here, we present a highly interpretable method, from binary evolution track interpolation. Our method implements simulation generation from irregularly sampled time series. Our results indicate that this method is appropriate for applications within binary population synthesis and computational astrophysics with time-dependent simulations in general. Furthermore, we point out and offer solutions to the difficulty surrounding evaluating the performance of signals exhibiting extreme morphologies akin to discontinuities.}, archive = {J_ApJ}, author = {Philipp M. Srivastava and Ugur Demir and Aggelos Katsaggelos and Vicky Kalogera and Shamal Lalvani and Elizabeth Teng and Tassos Fragos and Jeff J. Andrews and Simone S. Bavera and Max Briel and Seth Gossage and Konstantinos Kovlakas and Matthias U. Kruckow and Camille Liotine and Kyle A. Rocha and Meng Sun and Zepei Xing and Emmanouil Zapartas}, doi = {10.3847/1538-4357/adbe6b}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {154}, shortjournal = {The Astrophys. J.}, title = {Irregularly sampled time series interpolation for detailed binary evolution simulations}, volume = {984}, year = {2025}, }
• (2025). On the uniqueness and causal relationship of precursor activity to solar energetic events. i. transient Brightenings—Introduction and overview. ApJ, 984(2), 153. (www)

  @article{ , abstract = {The physical role played by small-scale activity that occurs before the sudden onset of solar energetic events (SEEs, i.e., solar flares and coronal mass ejections) remains in question, in particular as related to SEE initiation and early evolution. It is still unclear whether such precursor activity, often interpreted as plasma heating, particle acceleration, or early filament activation, is indicative of a pre-event phase or simply ongoing background activity. In this series, we statistically investigate the uniqueness and causal connection between precursors and SEEs using paired activity-quiet epochs. This first paper specifically introduces transient brightenings (TBs) and presents analysis regimes to study their role as precursors, including imaging of the solar atmosphere, magnetic field, and topology analysis. Applying these methods qualitatively to three cases, we find that, prior to solar flares, TBs (1) tend to occur in one large cluster close to the future flare ribbon location and below the separatrix surface of a coronal magnetic null point, (2) are cospatial with reconnection signatures in the lower solar atmosphere, such as bald patches and null-point fan traces, and (3) cluster in the vicinity of strong-gradient polarity inversion lines and regions of increased excess magnetic energy density. TBs are also observed during quiet epochs of the same active regions, but they appear in smaller clusters not following a clear spatial pattern, although sometimes associated with short, spatially intermittent bald patches and fan traces, but predominantly away from strong-gradient polarity inversion lines in areas with little excess energy density.}, archive = {J_ApJ}, author = {Karin Dissauer and Graham Barnes and KD Leka and Eric L. Wagner}, doi = {10.3847/1538-4357/adbf13}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {153}, shortjournal = {The Astrophys. J.}, title = {On the uniqueness and causal relationship of precursor activity to solar energetic events. i. transient Brightenings—Introduction and overview}, volume = {984}, year = {2025}, }
• (2025). Detection of the white dwarf spin of the long-orbital period magnetic cataclysmic variable v1082 sgr. ApJ, 984(2), 152. (www)

  @article{ , abstract = {We report on the discovery of circular polarization modulated with a period of 1.943 ± 0.002 hr in the cataclysmic variable V1082 Sgr. These findings unambiguously reveal the rotation of a magnetic white dwarf and establish its intermediate polar nature. Along with its extraordinary long orbital period ( P orb ) of 20.8 hr, the spin period ( P spin ) places this system in an extreme position of the P spin versus P orb distribution. The circular polarization phase diagram has a single peak and an amplitude smaller than 1%. These data were used to model the postshock region of the accretion flow on the white dwarf surface using the CYCLOPS code. We obtained a magnetic field in the white dwarf pole of 11 MG and a magnetospheric radius consistent with the coupling region at around 2–3 white dwarf radii. The P spin / P orb value and the estimated magnetic field momentum suggest that V1082 Sgr could be out of spin equilibrium or in a spin-up state, possibly in a stream accretion mode.}, archive = {J_ApJ}, author = {I. J. Lima and G. Tovmassian and C. V. Rodrigues and A. S. Oliveira and G. J. M. Luna and D. A. H. Buckley and K. M. G. Silva and A. C. Mattiuci and D. C. Souza and W. Schlindwein and F. Falkenberg and M. S. Palhares}, doi = {10.3847/1538-4357/adc380}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {152}, shortjournal = {The Astrophys. J.}, title = {Detection of the white dwarf spin of the long-orbital period magnetic cataclysmic variable v1082 sgr}, volume = {984}, year = {2025}, }
• (2025). An upper limit on the interstellar meteoroid flux at video sizes from the global meteor network. ApJ, 984(2), 151. (www)

  @article{ , abstract = {Material arriving at our solar system from the Galaxy may be detected on Earth in the form of meteors ablating in our atmosphere. Here, we report on a search for interstellar meteors within the highest-quality events in the Global Meteor Network (GMN) database. No events were detected that were conclusively hyperbolic with respect to the Sun; however, our search was not exhaustive and examined only the top 57% of events, with a deeper examination planned for future work. This study's effective meteoroid mass limit is 6.6 ± 0.8 × 10 −5 kg (5 mm diameter at a density of 1000 kg m −3 ). Theoretical rates of interstellar meteors at these sizes range from 3 to 200 events globally per year. The highest rates can already be largely excluded by this study, while at the lowest rates, GMN would have to observe for 25 more years to be 50% confident of seeing at least one event. GMN is thus well-positioned to provide substantial constraints on the interstellar population at these sizes over the coming years. This study's results are statistically compatible with a rate of interstellar meteors at the Earth at less than 1 per million meteoroid impacts at Earth at millimeter sizes, or a flux rate of less than 8 ± 2 × 10 −11 km −2 hr −1 at the 95% confidence level.}, archive = {J_ApJ}, author = {Paul Wiegert and Vanessa Tran and Cole Gregg and Denis Vida and Peter Brown}, doi = {10.3847/1538-4357/adc44f}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {151}, shortjournal = {The Astrophys. J.}, title = {An upper limit on the interstellar meteoroid flux at video sizes from the global meteor network}, volume = {984}, year = {2025}, }
• (2025). Scaling of particle heating in shocks and magnetic reconnection. ApJ, 984(2), 150. (www)

  @article{ , abstract = {Particles are heated efficiently through energy conversion processes, such as shocks and magnetic reconnection, in collisionless plasma environments. While empirical scaling laws for the temperature increase have been obtained, the precise mechanism of energy partition between ions and electrons remains unclear. Here we show, based on coupled theoretical and observational scaling analyses, that the temperature increase, Δ T , depends linearly on three factors: the available magnetic energy per particle, the Alfvén Mach number (or reconnection rate), and the characteristic spatial scale L . Based on statistical data sets obtained from Earth's plasma environment, we find that L is on the order of: (1) the ion gyroradius for ion heating at shocks; (2) the ion inertial length for ion heating in magnetic reconnection; and (3) the hybrid inertial length for electron heating in both shocks and magnetic reconnection. With these scales, we derive the ion-to-electron ratios of temperature increases as {\rm{\Delta }}{T}_{{\rm{i}}}/{\rm{\Delta }}{T}_{{\rm{e}}}={(3{\beta }_{{\rm{i}}}/2)}^{1/2}{({m}_{{\rm{i}}}/{m}_{{\rm{e}}})}^{1/4} for shocks and {\rm{\Delta }}{T}_{{\rm{i}}}/{\rm{\Delta }}{T}_{{\rm{e}}}={({m}_{{\rm{i}}}/{m}_{{\rm{e}}})}^{1/4} for magnetic reconnection, where β i is the ion plasma beta and m i and m e are the ion and electron particle masses, respectively. We anticipate that this study will serve as a starting point for a better understanding of particle heating in space plasmas, enabling more sophisticated modeling of its scaling and universality.}, archive = {J_ApJ}, author = {Mitsuo Oka and Tai D. Phan and Marit Øieroset and Daniel J. Gershman and Roy B. Torbert and James L. Burch and Vassilis Angelopoulos}, doi = {10.3847/1538-4357/adc5e5}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {150}, shortjournal = {The Astrophys. J.}, title = {Scaling of particle heating in shocks and magnetic reconnection}, volume = {984}, year = {2025}, }
• (2025). Evolution of the convective core mass during the main sequence. ApJ, 984(2), 149. (www)

  @article{ , abstract = {We construct a semianalytical model that describes the convective core mass evolution of massive stars experiencing mass loss during the main-sequence stage. We first conduct a suite of 1D stellar evolution calculations to build insight into how convective core masses behave under idealized mass loss. Based on these simulations, we find several universal relations between global properties of the star that hold regardless of the mass loss history. By combining these relations, we construct a semianalytic framework that can predict the convective core mass evolution for arbitrary mass-loss histories, and hence the helium core mass at the end of the main sequence. Our formulae improve upon existing methods for predicting the core mass in rapid population synthesis codes.}, archive = {J_ApJ}, author = {Minori Shikauchi and Ryosuke Hirai and Ilya Mandel}, doi = {10.3847/1538-4357/adc5fa}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {149}, shortjournal = {The Astrophys. J.}, title = {Evolution of the convective core mass during the main sequence}, volume = {984}, year = {2025}, }
• (2025). Deep photometric observations of ultrafaint milky way satellites centaurus i and eridanus IV*. ApJ, 984(2), 148. (www)

  @article{ , abstract = {We present deep Magellan+Megacam imaging of Centaurus I (Cen I) and Eridanus IV (Eri IV), two recently discovered Milky Way ultrafaint satellites. Our data reach ∼2–3 mag deeper than the discovery data from the DECam Local Volume Exploration Survey. We use these data to constrain their distances, structural properties (e.g., half-light radii, ellipticity, and position angle), and luminosities. We investigate whether these systems show signs of tidal disturbance and identify new potential member stars using Gaia EDR3. Our deep color–magnitude diagrams show that Cen I and Eri IV are consistent with an old ( τ ∼ 13.0 Gyr) and metal-poor ([Fe/H] ≤ −2.2) stellar population. We find Cen I to have a half-light radius of {r}_{h}=2.\,^{\prime} 60\pm 0.\,^{\prime} 30\, (90.6 ± 11 pc), an ellipticity of = 0.36 ± 0.05, a distance of D = 119.8 ± 4.1 kpc ( m − M = 20.39 ± 0.08 mag), and an absolute magnitude of M V = −5.39 ± 0.19. Similarly, Eri IV has {r}_{h}=3.\,^{\prime} 24\pm 0.\,^{\prime} 48\, (65.9 ± 10 pc), = 0.26 ± 0.09, D = 69.9 ± 3.6 kpc ( m − M = 19.22 ± 0.11 mag), and M V = −3.55 ± 0.24. These systems occupy a space on the size–luminosity plane consistent with other known Milky Way dwarf galaxies, which supports the findings from our previous spectroscopic follow-up. Cen I has a well-defined morphology that lacks any clear evidence of tidal disruption, whereas Eri IV hosts a significant extended feature with multiple possible interpretations.}, archive = {J_ApJ}, author = {Quinn O. Casey and Burçin Mutlu-Pakdil and David J. Sand and Andrew B. Pace and Denija Crnojević and Amandine Doliva-Dolinsky and William Cerny and Mairead E. Heiger and Alex H. Riley and Alexander P. Ji and Guilherme Limberg and Laurella Marin and Clara E. Martínez-Vázquez and Gustavo E. Medina and Ting S. Li and Sasha N. Campana and Astha Chaturvedi and Joanna D. Sakowska and Alfredo Zenteno and Julio A. Carballo-Bello and Mahdieh Navabi and Clecio R. Bom and (DELVE Collaboration)}, doi = {10.3847/1538-4357/adc67e}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {148}, shortjournal = {The Astrophys. J.}, title = {Deep photometric observations of ultrafaint milky way satellites centaurus i and eridanus IV*}, volume = {984}, year = {2025}, }
• (2025). Discovery of two ultra-diffuse galaxies with unusually bright globular cluster luminosity functions via a mark-dependently thinned point process (MATHPOP). ApJ, 984(2), 147. (www)

  @article{ , abstract = {We present MArk-dependently THinned POint Process (M athpop) , a novel method to infer the globular cluster (GC) counts in ultra-diffuse galaxies (UDGs) and low-surface brightness galaxies (LSBGs). Many known UDGs have a surprisingly high ratio of GC number to surface brightness. However, standard methods to infer GC counts in UDGs face various challenges, such as photometric measurement uncertainties, GC membership uncertainties, and assumptions about the GC luminosity functions (GCLFs). M athpop tackles these challenges using the mark-dependent thinned point process, enabling joint inference of the spatial and magnitude distributions of GCs. In doing so, M athpop allows us to infer and quantify the uncertainties in both GC counts and GCLFs with minimal assumptions. As a precursor to M athpop , we also address the data uncertainties coming from the selection process of GC candidates: we obtain probabilistic GC candidates instead of the traditional binary classification based on the color–magnitude diagram. We apply M athpop to 40 LSBGs in the Perseus cluster using GC catalogs from a Hubble Space Telescope imaging program. We then compare our results to those from an independent study using the standard method. We further calibrate and validate our approach through extensive simulations. Our approach reveals two LSBGs having GCLF turnover points much brighter than the canonical value with Bayes' factor being ∼4.5 and ∼2.5, respectively. An additional crude maximum-likelihood estimation and simulation study show that their GCLF TO points are approximately 0.9 mag and 1.1 mag brighter than the canonical value, with p -values of ∼10 −8 and ∼10 −5 , respectively.}, archive = {J_ApJ}, author = {Dayi (David) Li and Gwendolyn M. Eadie and Patrick E. Brown and William E. Harris and Roberto G. Abraham and Pieter van Dokkum and Steven R. Janssens and Samantha C. Berek and Shany Danieli and Aaron J. Romanowsky and Joshua S. Speagle}, doi = {10.3847/1538-4357/adc71f}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {147}, shortjournal = {The Astrophys. J.}, title = {Discovery of two ultra-diffuse galaxies with unusually bright globular cluster luminosity functions via a mark-dependently thinned point process (MATHPOP)}, volume = {984}, year = {2025}, }
• (2025). High-energy emission from the intrabinary shocks in redback pulsars. ApJ, 984(2), 146. (www)

  @article{ , abstract = {The intrabinary shocks (IBS) of spider pulsars emit nonthermal synchrotron X-rays from accelerated electrons and positrons in the shocked pulsar wind, likely energized by magnetic reconnection. In redback spider pulsars, the IBS typically wraps around the pulsar, leading to a near-normal IBS shock with relatively bright X-ray emission. The characteristic energies of radiating particles and the magnetic fields in the IBS suggest spectral features in the hard X-ray band. Here, we perform joint soft–hard X-ray analyses of three redback pulsars, J1723-2837, J2215+5135, and J2339-0533, including new J2215 NuSTAR data. We identify a significant cooling break in J1723-2837 and a marginal break in J2215+5135, while placing constraints on the break energy in J2339-0533. Interpreting these as synchrotron cooling features allows us to estimate the IBS magnetic field B IBS ∼ 40–100 G and place lower bounds on the maximum radiating electron energy. Our results constrain the magnetization of the pulsar wind as well as pair production in millisecond pulsar magnetospheres.}, archive = {J_ApJ}, author = {Andrew G. Sullivan and Roger W. Romani}, doi = {10.3847/1538-4357/adc720}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {146}, shortjournal = {The Astrophys. J.}, title = {High-energy emission from the intrabinary shocks in redback pulsars}, volume = {984}, year = {2025}, }
• (2025). Quasar milli-lensing and cold dark matter (TNG50) subhaloes. i. image splitting. ApJ, 984(2), 145. (www)

  @article{ , abstract = {We use numerical mass density profiles from the TNG50 simulation to study the impact of gravitational milli-lensing by dark matter subhaloes on the images of lensed quasars. Specifically, we study the formation of subimages and the probability of their detection. For high-concentration density profiles, the mass determines the amplitude of the image splitting, but for less compact subhaloes, the separation between subimages also depends on the interplay between the inner slope of the density profile and the macro-magnification induced by the lens galaxy. For a log-slope m = −2, close to the mean value of TNG50 density profiles, the detection possibilities increase with respect to less steep, commonly used, analytical models. For typical values of the concentration, 10 4 ≤ C v ≤ 10 6 , and macro-magnification μ ≥ 10, subhaloes in the entire studied mass range ( M sh ≥ 3.5 × 10 8 M ⊙ ) can produce separations between subimages detectable with the Hubble Space Telescope or JWST. Considering the absence of reported image splitting in optical observations of lensed quasars, we establish an upper limit on the subhaloes mass fraction {\alpha }_{0}^{{\rm{mix}}}=0.005\pm 0.003 , consistent within uncertainties with the abundance of lensing-efficient subhaloes directly inferred from the TNG50 simulation, {f}_{{\rm{TNG}}}^{{\rm{mix}}}=0.01\pm 0.01 . We show that subhalo density profiles that were initially proposed to explain anomalies in the gravitational arcs of three lensed quasar systems, have also the potential to cause observable point image splitting. This presents an intriguing statistical puzzle when comparing the absence of image splitting in 400 quasar images to the three claimed detections of subhaloes in a small sample of modeled gravitational arcs.}, archive = {J_ApJ}, author = {E. Mediavilla and J. Jiménez-Vicente and F. M. Heinze and J. Martín Camalich}, doi = {10.3847/1538-4357/adc724}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {145}, shortjournal = {The Astrophys. J.}, title = {Quasar milli-lensing and cold dark matter (TNG50) subhaloes. i. image splitting}, volume = {984}, year = {2025}, }
• (2025). Suppressed accretion onto massive black hole binaries surrounded by thin disks. ApJ, 984(2), 144. (www)

  @article{ , abstract = {We demonstrate that gas disks around binary systems might deliver gas to the binary components only when the circumbinary disk is relatively warm. We present new grid-based hydrodynamics simulations, performed with the binary on the grid and a locally isothermal equation of state, in which the binary is seen to functionally "stop accreting" if the orbital Mach number in the disk exceeds a threshold value of about 40. Above this threshold, the disk continues to extract angular momentum from the binary orbit, but it delivers very little mass to the black holes and instead piles up mass in a ring surrounding the binary. This ring will eventually become viscously relaxed and deliver mass to the binary at the large-scale inflow rate. However, we show that the timescale for such relaxation can far exceed the implied binary lifetime. We demonstrate that the ability of a binary–disk system to equilibrate is dependent on the efficiency at which accretion streams deposit mass onto the binary, which, in turn is highly sensitive to the thermodynamic conditions of the inner disk. If disks around massive black hole binaries do operate in such nonaccreting regimes, it suggests these systems may be dimmer than their single black hole counterparts but could exhibit dramatic rebrightening after the black holes inspiral and merge. This dimming begins in the UV/optical and could completely choke high-energy emission, such that these systems would likely be intrinsically X-ray weak with reddened continua, potentially resembling the spectra of "little red dots" recently identified in JWST observations.}, archive = {J_ApJ}, author = {Christopher Tiede and Jonathan Zrake and Andrew MacFadyen and Zoltán Haiman}, doi = {10.3847/1538-4357/adc727}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {144}, shortjournal = {The Astrophys. J.}, title = {Suppressed accretion onto massive black hole binaries surrounded by thin disks}, volume = {984}, year = {2025}, }
• (2025). “Ashfall” induced by molecular outflow in protostar evolution. II. analytical study on the maximum size of dust grains lifted by outflows. ApJ, 984(2), 143. (www)

  @article{ , abstract = {In this paper, we study the dust dynamics in the molecular outflow using an analytical magnetohydrodynamical outflow model. Specifically, we investigate the maximum size of dust grains {a}_{d\mathrm{,max}} that can be lifted by the outflow and whether they can escape into interstellar space. We also investigate the dependence of the maximum size of the dust grains on various outflow parameters, such as the mass ejection rate of the outflow \dot{M} , the disk size r disk , the mass of the central protostar M * , and the internal dust density ρ mat . We find the empirical formula for the maximum dust size as a function of the outflow parameters. Parameter {a}_{d\mathrm{,max}} depends on the parameters as {a}_{d\mathrm{,max}} ∝ {\dot{M}}^{1.0} {r}_{{\rm{disk}}}^{-0.44} {M}_{* }^{-0.82} {\rho }_{{\rm{mat}}}^{-1.0} . We also find that the dust grains with sizes of 100 μ m to 1 mm can be lifted by the outflow and can distribute well outside of the disk when the mass ejection rate of the outflow has a value of 10 −7 to 10 −6 M ⊙ yr −1 . This result is consistent with recent observations that show a correlation between the mass ejection rate of the outflow and the spectral index β of the dust opacity at the envelope scale.}, archive = {J_ApJ}, author = {Hayato Uchimura and Takahiro Kudoh and Yusuke Tsukamoto}, doi = {10.3847/1538-4357/adc806}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {143}, shortjournal = {The Astrophys. J.}, title = {“Ashfall” induced by molecular outflow in protostar evolution. II. analytical study on the maximum size of dust grains lifted by outflows}, volume = {984}, year = {2025}, }
• (2025). The GHOSDT simulations: I. magnetic support in gas-rich disks. ApJ, 984(2), 142. (www)

  @article{ , abstract = {Galaxies at redshift z ∼ 1–2 display high star formation rates with elevated cold gas fractions and column densities. Simulating a self-regulated interstellar medium (ISM) in a hydrodynamical, self-consistent context has proven challenging due to strong outflows triggered by supernova (SN) feedback. At sufficiently high gas column densities, if magnetic fields or other mitigating measures are not implemented, these outflows can prevent a quasi-steady disk from forming for several 100 Myr. To this end, we present GHOSDT (galaxy hydrodynamical simulations with SN-driven turbulence), a suite of magneto-hydrodynamical simulations that implement ISM physics at high resolution. We demonstrate that magnetic pressure is important in the dense ISM of gas-rich star-forming disks. We show that a relation between the magnetic field and gas surface density emerges naturally from our simulations. We argue that the magnetic field in the dense, star-forming gas may be set by the SN-driven turbulent gas motions. When compared to pure-hydrodynamical runs, we find that the inclusion of magnetic fields increases the cold gas fraction by up to 40%, reduces the disk scale height by up to a factor of ∼2, and reduces the star formation burstiness. In dense ( n > 100 cm −3 ) gas, we find steady-state magnetic field strengths of 10–40 μ G, comparable to those observed in Galactic molecular clouds. Finally, we demonstrate that our simulation framework is consistent with the E. C. Ostriker and C.-G. Kim pressure-regulated feedback-modulated theory of star formation and stellar feedback.}, archive = {J_ApJ}, author = {Alon Gurman and Ulrich P. Steinwandel and Chia-Yu Hu and Amiel Sternberg}, doi = {10.3847/1538-4357/adc814}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {142}, shortjournal = {The Astrophys. J.}, title = {The GHOSDT simulations: I. magnetic support in gas-rich disks}, volume = {984}, year = {2025}, }
• (2025). The detectability of coronal mass ejections in the low corona using multislit extreme-ultraviolet spectroscopy. ApJ, 984(2), 141. (www)

  @article{ , abstract = {The spectra of coronal mass ejections (CMEs) in the low corona play a crucial role in understanding their origins and physical mechanisms and enhancing space weather forecasting. However, capturing these spectra faces significant challenges. This paper introduces a scheme of a multislit spectrometer design with five slits, acquiring the global spectra of the solar corona simultaneously with a focus on the spectra of CMEs in the low corona. The chosen wavelength range of the spectrometer (170–180 Å) includes four extreme ultraviolet emission lines (Fe x 174.53 Å, Fe ix 171.07 Å, Fe x 175.26 Å, Fe x 177.24 Å), which provides information on the plasma velocity, density, and temperature. Utilizing a numerical simulation of the global corona for both the on-disk and the off-limb scenarios, we focus on resolving the ambiguity associated with various Doppler velocity components of CMEs, particularly for a fast CME in the low corona. A new application of our decomposition technique is adopted, enabling the successful identification of multiple discrete CME velocity components. Our findings demonstrate a strong correlation between the synthetic model spectra and the inverted results, indicating the robustness of our decomposition method and its significant potential for global monitoring of the solar corona, including CMEs.}, archive = {J_ApJ}, author = {Lami Chan and Xianyong Bai and Hui Tian and Yufei Feng and Yu Xu and Tibor Török and Yuhang Gao and Tanmoy Samanta and Zheng Sun}, doi = {10.3847/1538-4357/adc10a}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {141}, shortjournal = {The Astrophys. J.}, title = {The detectability of coronal mass ejections in the low corona using multislit extreme-ultraviolet spectroscopy}, volume = {984}, year = {2025}, }
• (2025). The morphology and kinematics of a giant, symmetric nebula around a radio-loud quasar 3C 57: Extended rotating gas or biconical outflows?. ApJ, 984(2), 140. (www)

  @article{ , abstract = {Gas flows between galaxies and the circumgalactic medium play a crucial role in galaxy evolution. When ionized by a quasar, these gas flows can be directly traced as giant nebulae. We present a study of a giant nebula around a radio-loud quasar, 3C 57 at z ≈ 0.672. Observations from MUSE reveal that the nebula is elongated with a major axis of 70 kpc and a minor axis of 40 kpc. The nebula displays an approximately symmetric blueshifted–redshifted pattern along the major axis and multicomponent emission features in its [O II ] and [O III ] profiles. The morphology and kinematics can be explained as rotating gas or biconical outflow, both of which qualitatively reproduce the observed position–velocity diagram. The 3C 57 nebula is significantly more kinematically disturbed, with W 80 (the line width encompassing 80% of the flux) of approximately 300–400 km s −1 , compared to H i gas in local early-type galaxies, which typically shows W 80 ≈ 50 km s −1 . This velocity dispersion is comparable to the gas in cool-core clusters despite originating in a group 100 times less massive. For biconical outflow models, the inferred 10°–20° inclination angle is in tension with the unobscured nature of the quasar, as the dusty torus is expected to be perpendicular to the outflow. Neither a quiescent rotating gas origin nor an biconical outflow fully reproduces the observed kinematics and morphology of the 3C 57 nebula, suggesting a more intricate origin likely involving both rotation and active galactic nuclei feedback.}, archive = {J_ApJ}, author = {Zhuoqi (Will) Liu and Sean D. Johnson and Jennifer I-Hsiu Li and Benoît Epinat and Gwen C. Rudie and Ana Monreal-Ibero and Sebastiano Cantalupo and Zhijie Qu and Mandy C. Chen and Wolfram Kollatschny and Sowgat Muzahid and Fakhri S. Zahedy and Elise Kesler and Nishant Mishra}, doi = {10.3847/1538-4357/adc1bf}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {140}, shortjournal = {The Astrophys. J.}, title = {The morphology and kinematics of a giant, symmetric nebula around a radio-loud quasar 3C 57: Extended rotating gas or biconical outflows?}, volume = {984}, year = {2025}, }
• (2025). Pulse profile variability of PSR j1022+1001 in NANOGrav data. ApJ, 984(2), 139. (www)

  @article{ , abstract = {Pulse profile stability is a central assumption of standard pulsar timing methods. Thus, it is important for pulsar timing array experiments such as the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) to account for any pulse profile variability present in their data sets. We show that in the NANOGrav 15 yr data set, the integrated pulse profile of PSR J1022+1001 as seen by the Arecibo radio telescope at 430, 1380, and 2030 MHz varies considerably in its shape from observation to observation. We investigate the possibility that this is due to the "ideal feed assumption" (IFA), on which NANOGrav's routine polarization calibration procedure relies. PSR J1022+1001 is  ∼90% polarized in one pulse profile component, and also has significant levels of circular polarization. Time-dependent deviations in the feed's polarimetric response (PR) could cause mixing between the intensity I and the other Stokes parameters, leading to the observed variability. We calibrate the PR using a mixture of measurement equation modeling and measurement equation template matching techniques. The resulting profiles are no less variable than those calibrated using the IFA method, nor do they provide an improvement in the timing quality of this pulsar. We observe the pulse shape in 25 MHz bandwidths to vary consistently across the band, which cannot be explained by interstellar scintillation in combination with profile evolution with frequency. Instead, we favor phenomena intrinsic to the pulsar as the cause.}, archive = {J_ApJ}, author = {William Fiore and Maura A. McLaughlin and Gabriella Agazie and Akash Anumarlapudi and Anne M. Archibald and Zaven Arzoumanian and Paul T. Baker and Paul R. Brook and H. Thankful Cromartie and Kathryn Crowter and Megan E. DeCesar and Paul B. Demorest and Lankeswar Dey and Timothy Dolch and Elizabeth C. Ferrara and Emmanuel Fonseca and Gabriel E. Freedman and Nate Garver-Daniels and Peter A. Gentile and Joseph Glaser and Deborah C. Good and Jeffrey S. Hazboun and Ross J. Jennings and Megan L. Jones and David L. Kaplan and Matthew Kerr and Michael T. Lam and Duncan R. Lorimer and Jing Luo and Ryan S. Lynch and Alexander McEwen and Natasha McMann and Bradley W. Meyers and Cherry Ng and David J. Nice and Timothy T. Pennucci and Benetge B. P. Perera and Nihan S. Pol and Henri A. Radovan and Scott M. Ransom and Paul S. Ray and Ann Schmiedekamp and Carl Schmiedekamp and Brent J. Shapiro-Albert and Ingrid H. Stairs and Kevin Stovall and Abhimanyu Susobhanan and Joseph K. Swiggum and Haley M. Wahl}, doi = {10.3847/1538-4357/adc255}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {139}, shortjournal = {The Astrophys. J.}, title = {Pulse profile variability of PSR j1022+1001 in NANOGrav data}, volume = {984}, year = {2025}, }
• (2025). Formation of all three C2H4O Isomers—Ethylene oxide (c-C2H4O), acetaldehyde (CH3CHO), and vinyl alcohol (CH2CHOH)—in ethanol-containing interstellar analog ices. ApJ, 984(2), 138. (www)

  @article{ , abstract = {Oxygen-containing complex organic molecules are key precursors to biorelevant compounds fundamental for the origins of life. However, the untangling of their interstellar formation mechanisms has just scratched the surface, especially for oxygen-containing cyclic molecules. Here, we present the first laboratory simulation experiments featuring the formation of all three C 2 H 4 O isomers—ethylene oxide ( c –C 2 H 4 O), acetaldehyde (CH 3 CHO), and vinyl alcohol (CH 2 CHOH)—in low-temperature model interstellar ices composed of carbon monoxide (CO) and ethanol (C 2 H 5 OH). Ice mixtures were exposed to galactic cosmic-ray proxies with an irradiation dose equivalent to a cold molecular cloud aged (7 ± 2) × 10 5 yr. These biorelevant species were detected in the gas phase through isomer-selective photoionization reflectron time-of-flight mass spectrometry during temperature-programmed desorption. Isotopic labeling experiments reveal that ethylene oxide is produced from ethanol alone, providing the first experimental evidence to support the hypothesis that ethanol serves as a precursor to the prototype epoxide in interstellar ices. These findings reveal feasible pathways for the formation of all three C 2 H 4 O isomers in ethanol-rich interstellar ices, offering valuable constraints on astrochemical models for their formation. Our results suggest that ethanol is a critical precursor to C 2 H 4 O isomers in interstellar environments, representing a critical step toward unraveling the formation mechanisms of oxygen-containing cyclic molecules, aldehydes, and their enol tautomers from alcohols in interstellar ices.}, archive = {J_ApJ}, author = {Jia Wang and Chaojiang Zhang and Joshua H. Marks and Ralf I. Kaiser}, doi = {10.3847/1538-4357/adc308}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {138}, shortjournal = {The Astrophys. J.}, title = {Formation of all three C2H4O Isomers—Ethylene oxide (c-C2H4O), acetaldehyde (CH3CHO), and vinyl alcohol (CH2CHOH)—in ethanol-containing interstellar analog ices}, volume = {984}, year = {2025}, }
• (2025). Testing tidal theory using gaia binaries: The red giant branch. ApJ, 984(2), 137. (www)

  @article{ , abstract = {Tidal interaction is a major ingredient in the theory of binary evolution. Here, we study tidal circularization in binaries with red giant primaries. We compute the tidal evolution for binaries as their primary stars evolve along the red giant branch, under dissipation of dynamical tides in the convective envelope. We then compare this evolution with a sample of ∼30,000 red giant binaries reported by Gaia DR3. These binaries clearly show the expected gradual advance of tidal circularization, as the primary expands. But some tension with theory remains. While our calculations always predict a critical separation for tidal circularization at about 3−4 times the stellar radii, binaries with less evolved giants are observed to be circularized out to about twice as far. They also exhibit an overly extended "cool island," a collection of circular orbits that reach a couple of times beyond the circularization limit. These discrepancies are reminiscent of, but less severe than, the situation for main-sequence binaries. We also find that tides can spin giant stars up to rotation rates that should affect their mass-loss. Additionally, many binaries may begin mass transfer while still eccentric.}, archive = {J_ApJ}, author = {Janosz W. Dewberry and Yanqin Wu}, doi = {10.3847/1538-4357/adc37e}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {137}, shortjournal = {The Astrophys. J.}, title = {Testing tidal theory using gaia binaries: The red giant branch}, volume = {984}, year = {2025}, }
• (2025). A multiwavelength light-curve analysis of the classical nova v392 per: Optical contribution from an irradiated accretion disk during the nova wind phase. ApJ, 984(2), 136. (www)

  @article{ , abstract = {The classical nova V392 Per 2018 is characterized by a very fast optical decline, a long binary orbital period of 3.23 days, detection of GeV gamma rays, and almost identical decay trends of the B , V , and I C light curves. The last feature is unique because most novae develop strong emission lines in the nebular phase and these lines contribute especially to the B and V bands and cause large differences between the BV and I C light curves. This unique feature can be understood if the optical flux is dominated by continuum until the late phase of the nova outburst. Such continuum radiation is emitted by a bright accretion disk irradiated by a hydrogen-burning white dwarf (WD) and a viscous heating disk with a high mass accretion rate after the hydrogen burning ends. We present a comprehensive nova outburst model that reproduces all of these light curves. We determine the WD mass to be M WD = 1.35–1.37 M ⊙ and the distance modulus in the V band to be ( m − M ) V = 14.6 ± 0.2; the distance is d = 3.45 ± 0.5 kpc for the reddening of E ( B − V ) = 0.62.}, archive = {J_ApJ}, author = {Izumi Hachisu and Mariko Kato}, doi = {10.3847/1538-4357/adc38a}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {136}, shortjournal = {The Astrophys. J.}, title = {A multiwavelength light-curve analysis of the classical nova v392 per: Optical contribution from an irradiated accretion disk during the nova wind phase}, volume = {984}, year = {2025}, }
• (2025). ChemicalUniverseMachine. i. uncovering the cosmic evolution of metals in the Galaxy–Interstellar Medium–Circumgalactic medium ecosystem. ApJ, 984(2), 135. (www)

  @article{ , abstract = {We present an empirical chemical evolution model that explains the distribution of metals in the interstellar medium (ISM) and the circumgalactic medium (CGM) of galaxies based on the U niverse M achine and N eutral U niverse M achine models in the framework of ΛCDM structure formation. We parameterize the fractions of outflowing metals returned and mixed into the multiphase ISM of the star-forming regions ( f H2 ) and into the neutral gas regions ( f H I ); metal production, transfer, and dilution are caused by star formation, galaxy mergers, and gas inflow from the intergalactic medium, respectively, with rates determined by the ( N eutral) U niverse M achine models. Using a Markov Chain Monte Carlo algorithm, we explore the posterior distributions of metal return and mixing consistent with observed mass–metallicity relations in H ii regions (at 0 < z < 5), H i damped Ly α systems (at 1 < z < 4), and the CGM (at z = 0). We find that the fraction of metals present in the ISM, f H2 + f H I , increases with halo mass from  ∼20% at 10 10 M ⊙ to  ∼80% at 10 13 M ⊙ . These fractions increase mildly at higher redshifts, to  ∼30% at 10 10 M ⊙ and  ∼80% at 10 13 M ⊙ at z = 5. Interestingly, there is no significant redshift evolution of f H2 + f H I at fixed circular velocity, suggesting that the metal distribution between the ISM and CGM is universally determined by the halo potential well depth. CGM metal enrichment is thus slow in high- z halos with deep potential wells. While f H2 monotonically increases with halo mass, f HI peaks at  ∼10 12 −10 13 M ⊙ , suggesting that reinfall may be inefficient in larger-mass halos.}, archive = {J_ApJ}, author = {Moka Nishigaki and Peter Behroozi and Masami Ouchi and Hong Guo and Rachel S. Somerville and Anna R. Gallazzi and Kimihiko Nakajima and Kuria Watanabe}, doi = {10.3847/1538-4357/adc43c}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {135}, shortjournal = {The Astrophys. J.}, title = {ChemicalUniverseMachine. i. uncovering the cosmic evolution of metals in the Galaxy–Interstellar Medium–Circumgalactic medium ecosystem}, volume = {984}, year = {2025}, }
• (2025). The progenitor systems of classical novae in m31. ApJ, 984(2), 134. (www)

  @article{ , abstract = {We present the first characterization of the statistical relationship between a large sample of novae in M31 and their progenitor stellar populations in the form of a delay time distribution. To this end, we leverage the spatially resolved stellar age distribution of the M31 disk derived from deep Hubble Space Telescope photometry by the Panchromatic Hubble Andromeda Treasury survey and a large catalog of novae in M31. Our delay time distribution has two statistically significant detections: one population of nova progenitors with ages between 2 and 3.2 Gyr and an unnormalized rate of ( {3.7}_{-3.5}^{+6.8}\pm 2.1)\times {10}^{-9} events M ⊙ −1 , and another of ages between 7.9 Gyr and the age of the Universe with ( {4.8}_{-0.9}^{+1.0}\pm 0.2)\times {10}^{-9} events M ⊙ −1 (uncertainties are statistical and systematic, respectively). Together with the upper limits we derive at other time bins, these detections are consistent with either a constant production efficiency or a higher production efficiency of novae at earlier delay times.}, archive = {J_ApJ}, author = {C. S. Abelson and Carles Badenes and Laura Chomiuk and Benjamin F. Williams and Katelyn Breivik and L. Galbany and C. Jiménez-Palau}, doi = {10.3847/1538-4357/adc68c}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {134}, shortjournal = {The Astrophys. J.}, title = {The progenitor systems of classical novae in m31}, volume = {984}, year = {2025}, }
• (2025). Kinetic-scale mirror mode storm embedded in a flux rope in the solar wind. ApJ, 984(2), 133. (www)

  @article{ , abstract = {Mirror modes are ubiquitous in the space plasma environment. Mirror mode storms are successive trains of mirror modes, lasting for a long time. Previous studies generally focused on large-scale mirror mode storms. However, studies concerning kinetic-scale mirror mode storms are still lacking. In this work, we report a kinetic-scale mirror mode storm embedded in a magnetic flux rope in the near-Earth solar wind for the first time. As the mirror mode instability develops from unstable to marginally stable, the structures of the mirror mode that make up the mirror mode storm present a variation from small-amplitude dense peaks to large-amplitude sparse holes. With joint observations from the Magnetospheric Multiscale mission, ACE, and Wind, it is found that this mirror mode storm has been excited before reaching the near-Earth region. This kinetic-scale mirror mode storm might be caused by compression between slow and fast plasma flows inside the flux rope. Our observations provide a possible source and mechanism for the generation of kinetic-scale mirror mode storms.}, archive = {J_ApJ}, author = {L. Yu and S. Y. Huang and Z. G. Yuan and K. Jiang and H. H. Wu and Q. Y. Xiong and R. T. Lin and Z. Wang and Y. T. Tang and H. Bai}, doi = {10.3847/1538-4357/adc72e}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {133}, shortjournal = {The Astrophys. J.}, title = {Kinetic-scale mirror mode storm embedded in a flux rope in the solar wind}, volume = {984}, year = {2025}, }
• (2025). X-ray constraints on wandering black holes in stripped galaxy nuclei in the halo of NGC 5128. ApJ, 984(2), 132. (www)

  @article{ , abstract = {A subset of galaxies have dense nuclei, and when these galaxies are accreted and tidally stripped, the nuclei can masquerade as globular clusters in the halos of large galaxies. If these nuclei contain massive central black holes, some may accrete gas and become observable as active galactic nuclei. Previous studies have found that candidate stripped nuclei rarely host luminous X-ray sources, but these studies were typically restricted to both the most massive candidate nuclei and the most luminous X-ray sources. Here we use new and archival Chandra and XMM-Newton data to search for X-ray emission in a near-complete sample of massive globular clusters and candidate stripped nuclei in the nearest accessible elliptical galaxy, NGC 5128. This sample has the unique advantage that the candidate stripped nuclei are identified dynamically via elevated mass-to-light ratios ( M / L V ). Our central result is that 5/22 ( 2{3}_{-6}^{+11} %) of the candidate stripped nuclei have X-ray sources down to a typical limit of L X ∼ 5 × 10 36 erg s −1 , a fraction lower than or comparable to that among massive clusters with normal M / L V (16/41; 3{9}_{-7}^{+8} %). Hence we confirm and extend the result that nearly all X-ray sources in stripped nuclei are likely to be X-ray binaries rather than active galactic nuclei. If the candidate stripped nuclei have black holes of typical masses ∼2 × 10 5 M ⊙ needed to explain their elevated M / L V , then they have typical Eddington ratios of ≲ 2 × 10 −6 . This suggests that it will be challenging to conduct an accretion census of wandering black holes around even nearby galaxies.}, archive = {J_ApJ}, author = {Samuel L. Feyan and Ryan Urquhart and Jay Strader and Anil C. Seth and David J. Sand and Nelson Caldwell and Denija Crnojević and Antoine Dumont and Karina Voggel}, doi = {10.3847/1538-4357/adc7b9}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {132}, shortjournal = {The Astrophys. J.}, title = {X-ray constraints on wandering black holes in stripped galaxy nuclei in the halo of NGC 5128}, volume = {984}, year = {2025}, }
• (2025). Solar wind control of the martian magnetotail current sheet and magnetic reconnection. ApJ, 984(2), 131. (www)

  @article{ , abstract = {Magnetic reconnection is a rapid process that releases magnetic free energy stored in current sheets (CSs), driving various explosive phenomena throughout the Universe. In planets within the solar system, reconnection is controlled by both the solar wind and the planet's magnetic field and rotation. In this study, we perform a statistical analysis of the characteristics of CSs and reconnection events in the Martian magnetotail, considering varying solar wind conditions and local crustal field variations. The results show that higher solar wind dynamic pressure leads to a significantly increased probability of reconnection, primarily due to the enhanced cross-tail current density. In contrast, the orientation of interplanetary magnetic fields and local crustal anomalies predominantly affect the spatial distribution of CSs and reconnection events. Moreover, high solar wind dynamic pressure significantly enhances the average tailward flux of hydrogen and oxygen ions, likely attributable to the enhanced pickup of planetary ions.}, archive = {J_ApJ}, author = {Lei Wang and Can Huang and Aimin Du and Yasong Ge and Junyu Zhao and Dongke Chen}, doi = {10.3847/1538-4357/adc925}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {131}, shortjournal = {The Astrophys. J.}, title = {Solar wind control of the martian magnetotail current sheet and magnetic reconnection}, volume = {984}, year = {2025}, }
• (2025). A phase-resolved view of millihertz quasiperiodic oscillations in the ultraluminous X-ray source m51 ULX-7: Evidence for a magnetically truncated disk and geometrical beaming. ApJ, 984(2), 130. (www)

  @article{ , abstract = {X-ray quasiperiodic oscillations (QPOs) are commonly observed in Galactic X-ray binaries and extragalactic ultraluminous X-ray sources (ULXs). In this study, we perform a phase-resolved analysis of recently discovered X-ray mHz QPOs in M51 ULX-7. This represents the first detailed phase-resolved analysis of QPOs conducted in ULXs. Our findings reveal that the amplitude of the mHz QPO slightly increases with photon energy, accompanied by a narrowing of the phase modulation profile. The phase-resolved spectroscopy indicates significant variability in the energy spectrum: both disk blackbody components exhibit marked variations on the QPO timescale, with the low-temperature component demonstrating significant synchronous changes in the disk temperature and luminosity, showing a positive correlation between these two parameters throughout the QPO cycle. This correlation supports the hypothesis that the disk inner radius corresponds to the magnetospheric radius, which slightly varies with the accretion rate. Our results suggest that the soft component, without beaming, originates from a magnetically truncated outer disk, while the hard component is geometrically beamed from the inner funnel regions.}, archive = {J_ApJ}, author = {Qing-Cang Shui and Shu Zhang and Hua Feng and Yu-Peng Chen and Shuang-Nan Zhang and Jing-Qiang Peng}, doi = {10.3847/1538-4357/adc98f}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {130}, shortjournal = {The Astrophys. J.}, title = {A phase-resolved view of millihertz quasiperiodic oscillations in the ultraluminous X-ray source m51 ULX-7: Evidence for a magnetically truncated disk and geometrical beaming}, volume = {984}, year = {2025}, }
• (2025). The impact of interplanetary magnetic field intensity on the escape of heavy ions from the martian magnetotail. ApJ, 984(2), 129. (www)

  @article{ , abstract = {The interplanetary magnetic field (IMF) is one of the primary factors influencing the Martian plasma environment. In this study, a multifluid magnetohydrodynamic model is adopted to investigate how variations in IMF affect planetary ion escape, particularly the tailward escape flux. Our results reveal that for nominal IMF direction ( 56^\circ Parker spiral), as IMF intensity increases, the ion escape rate decreases considerably. This reduction is primarily due to the decrease in planetary ion density in the plume and the magnetotail, which is caused by the lower ion production rate through the charge exchange process under high IMF conditions. With high IMF conditions, the dynamo at the bow shock is significantly enhanced, leading to a more severe deceleration of solar wind protons and fewer protons entering the magnetosheath. Consequently, intensified electromagnetic fields create a stronger induced magnetosphere, which shields the Martian ionosphere and atmosphere. Although the enhanced loading process for planetary ions results in higher ion escape velocities, the overall ion escape fluxes decrease due to the significant reduction in planetary ion density.}, archive = {J_ApJ}, author = {Yihui Song and Haoyu Lu and Jinbin Cao and Shibang Li and Xiaoshu Wu and Jianxuan Wang and Nihan Chen and Yasong Ge and Yuchen Cao and Jianing Zhao}, doi = {10.3847/1538-4357/adc9b1}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {129}, shortjournal = {The Astrophys. J.}, title = {The impact of interplanetary magnetic field intensity on the escape of heavy ions from the martian magnetotail}, volume = {984}, year = {2025}, }
• (2025). Monitoring the dust emission from r aqr with SOFIA: Eclipse and periastron passage. ApJ, 984(2), 128. (www)

  @article{ , abstract = {We present infrared (IR) spectra from our monitoring of the symbiotic Mira, R Aquarii, using the Stratospheric Observatory for Infrared Astronomy. New mid-IR photometric and spectroscopic observations using the FORCAST instrument were obtained in 2022 September, when the system was well into the eclipse phase. The 10 μ m silicate feature has increased in strength since the previous observations, obtained in 2019 October. Radiative transfer models of the emission show that the dust density has increased by a factor of about 2 in this period. Three epochs of far-IR photometric observations obtained with the HAWC+ instrument between 2018 July and 2020 September are also presented here. The emission at the sampled wavelength bands ranging from 53 to 214 μ m does not vary significantly, in contrast to the mid-IR silicate dust emission that shows large variations. The models suggest that the far-IR emission arises much further out in the circumstellar dust shell and is not affected by the dynamics in the inner regions that impact the mid-IR emission.}, archive = {J_ApJ}, author = {Eric Omelian and Ravi Sankrit and Steven Goldman and Uma Gorti}, doi = {10.3847/1538-4357/adcab7}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {128}, shortjournal = {The Astrophys. J.}, title = {Monitoring the dust emission from r aqr with SOFIA: Eclipse and periastron passage}, volume = {984}, year = {2025}, }
• (2025). Flat circular velocities on a megaparsec scale from the ΛCDM model. ApJ, 984(2), 127. (www)

  @article{ , abstract = {A recent study using weak gravitational lensing reveals that there are some isolated galaxies with almost flat rotation curves at very large distances from the galactic centers. According to the authors of the study, this provides a strong challenge to the standard cold dark matter model, since the dark haloes are too small to explain their observations, especially for small stellar masses. In this article, we show that by improving their model, the virial radius is larger than their estimates. The Navarro–Frenk–White rotational curve, and especially the pseudo-isothermal one, are in agreement with their flat rotational curves, especially for the larger baryonic mass bins used by the authors.}, archive = {J_ApJ}, author = {Antonino Del Popolo and Man Ho Chan}, doi = {10.3847/1538-4357/adcc1c}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {127}, shortjournal = {The Astrophys. J.}, title = {Flat circular velocities on a megaparsec scale from the ΛCDM model}, volume = {984}, year = {2025}, }
• (2025). The nature of spectral variability of the accreting pulsar centaurus X-3 unveiled by NuSTAR observation covering two orbital cycles. ApJ, 984(2), 126. (www)

  @article{ , abstract = {We conducted a 369 ks NuSTAR observation on the X-ray pulsar Centaurus X-3, which covered two consecutive orbital cycles of the source, including two eclipse durations. We investigated the orbital-phase spectral variability over the two orbital cycles. We divided the entire observation data into multiple segments, each covering an orbital interval of ΔΦ = 0.005. The phenomenological spectral modeling applied to these orbital-phase-resolved spectra reveals that the photon index is the key parameter with the most variability and a strong correlation with the continuum flux. The photon index becomes softer during the high-flux phases and harder in the low-flux phases. The relation between the photon index and continuum flux remains consistent when investigating specific spin phases, suggesting that the spectral variability originates from extrinsic factors apart from the neutron star. Furthermore, the 3–5 keV pulse fraction also exhibits variability, being enhanced in the high-flux phases and suppressed in the low-flux phases, which indicates the presence of multiple emission components with different pulse fractions. These phenomenological analysis results enabled us to estimate the physical origin of the spectral variability. We successfully fitted the orbital-phase-resolved spectra with a physical model that assumes (1) stable emission from the neutron star, (2) attenuation by inhomogeneous, clumpy stellar wind, and (3) an additional nonpulsed emission component arising from thermal emission from the accretion disk. The thermal emission from the accretion disk can be described by a blackbody with a temperature of kT ∼ 0.5 keV and a luminosity of ∼10 37 erg s −1 .}, archive = {J_ApJ}, author = {Tsubasa Tamba and Hirokazu Odaka and Atsushi Tanimoto and Hiromasa Suzuki and Satoshi Takashima and Aya Bamba}, doi = {10.3847/1538-4357/adcc1e}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {126}, shortjournal = {The Astrophys. J.}, title = {The nature of spectral variability of the accreting pulsar centaurus X-3 unveiled by NuSTAR observation covering two orbital cycles}, volume = {984}, year = {2025}, }
• (2025). K dwarf radius inflation and a 10 gyr spin-down clock unveiled through asteroseismology of HD 219134 from the keck planet finder. ApJ, 984(2), 125. (www)

  @article{ , abstract = {We present the first asteroseismic analysis of the K3 V planet host HD 219134 based on four consecutive nights of radial velocities collected with the Keck Planet Finder. We apply Gold deconvolution to the power spectrum to disentangle modes from side lobes in the spectral window and extract 25 mode frequencies with spherical degrees 0 ≤ ℓ ≤ 3. We derive the fundamental properties using five different evolutionary-modeling pipelines and report a mass of 0.763 ± 0.020 (stat)  ± 0.007 (sys) M ⊙ , a radius of 0.748 ± 0.007 (stat)  ± 0.002 (sys) R ⊙ , and an age of 10.151 ± 1.520 (stat)  ± 0.810 (sys) Gyr. Compared to the interferometric radius 0.783 ± 0.005 R ⊙ , the asteroseismic radius is 4% smaller at the 4 σ level—a discrepancy not easily explained by known interferometric systematics, modeling assumptions on atmospheric boundary conditions and mixing lengths, magnetic fields, or tidal heating. HD 219134 is the first main-sequence star cooler than 5000 K with an asteroseismic age estimate and will serve as a critical calibration point for stellar spin-down relations. We show that existing calibrated prescriptions for angular momentum loss, incorporating weakened magnetic braking with asteroseismically constrained stellar parameters, accurately reproduce the observed rotation period. Additionally, we revised the masses and radii of the super-Earths in the system, which support their having Earth-like compositions. Finally, we confirm that the oscillation amplitude in radial velocity scales as ( L / M ) 1.5 in K dwarfs, in contrast to the ( L / M ) 0.7 relation observed in G dwarfs. These findings provide significant insights into the structure and angular momentum loss of K-type stars.}, archive = {J_ApJ}, author = {Yaguang Li and Daniel Huber and J. M. Joel Ong and Jennifer van Saders and R. R. Costa and Jens Reersted Larsen and Sarbani Basu and Timothy R. Bedding and Fei Dai and Ashley Chontos and Theron W. Carmichael and Daniel Hey and Hans Kjeldsen and Marc Hon and Tiago L. Campante and Mário J. P. F. G. Monteiro and Mia Sloth Lundkvist and Nicholas Saunders and Howard Isaacson and Andrew W. Howard and Steven R. Gibson and Samuel Halverson and Kodi Rider and Arpita Roy and Ashley D. Baker and Jerry Edelstein and Chris Smith and Benjamin J. Fulton and Josh Walawender}, doi = {10.3847/1538-4357/adc737}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {125}, shortjournal = {The Astrophys. J.}, title = {K dwarf radius inflation and a 10 gyr spin-down clock unveiled through asteroseismology of HD 219134 from the keck planet finder}, volume = {984}, year = {2025}, }
• (2025). Rapidly varying ionization features in a quasi-periodic eruption: A homologous expansion model for the spectroscopic evolution. ApJ, 984(2), 124. (www)

  @article{ , abstract = {Quasi-periodic eruptions (QPEs) are recurring bursts of soft X-ray emission from supermassive black holes, which a growing class of models explains via extreme mass ratio inspirals (EMRIs). QPEs exhibit blackbody-like emission with significant temperature evolution, but the minimal information content of their almost pure-thermal spectra has limited physical constraints. Here we study the recently discovered QPEs in ZTF19acnskyy ("Ansky"), which show absorption-like features evolving dramatically within eruptions and correlating strongly with continuum temperature and luminosity, further probing the conditions underlying the emission surface. The absorption features are well described by dense ionized plasma of column density N H ≳ 10 21 cm −2 , blueshift 0.06 ≲ v / c ≲ 0.4, and either collisional or photoionization equilibrium. With high-resolution spectra, we also detect ionized blueshifted emission lines suggesting a nitrogen overabundance of 21.{7}_{-11.0}^{+18.5}\times solar. We interpret our results with orbiter–disk collisions in an EMRI system, in which each impact drives a shock that locally heats the disk and expels X-ray-emitting debris undergoing radiation-pressure-driven homologous expansion. We explore an analytical toy model that links the rapid change in absorption lines to the evolution of the ionization parameter and the photosphere radius, and we suggest that ∼10 −3 M ⊙ ejected per eruption with expansion velocities up to {v}_{{\rm{\max }}}\sim 0.15c can reproduce the absorption features. With these assumptions, we show that a P Cygni profile in a spherical expansion geometry qualitatively matches the observed line profiles. Our work takes a first step toward extending existing physical models for QPEs to address their implications for spectral line formation.}, archive = {J_ApJ}, author = {Joheen Chakraborty and Peter Kosec and Erin Kara and Giovanni Miniutti and Riccardo Arcodia and Ehud Behar and Margherita Giustini and Lorena Hernández-García and Megan Masterson and Erwan Quintin and Claudio Ricci and Paula Sánchez-Sáez}, doi = {10.3847/1538-4357/adb972}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {124}, shortjournal = {The Astrophys. J.}, title = {Rapidly varying ionization features in a quasi-periodic eruption: A homologous expansion model for the spectroscopic evolution}, volume = {984}, year = {2025}, }
• (2025). The distribution of ultrahigh-energy cosmic rays along the supergalactic plane measured at the pierre auger observatory. ApJ, 984(2), 123. (www)

  @article{ , abstract = {Ultrahigh-energy cosmic rays are known to be mainly of extragalactic origin, and their propagation is limited by energy losses, so their arrival directions are expected to correlate with the large-scale structure of the local Universe. In this work, we investigate the possible presence of intermediate-scale excesses in the flux of the most energetic cosmic rays from the direction of the supergalactic plane region using events with energies above 20 EeV recorded with the surface detector array of the Pierre Auger Observatory up to 2022 December 31, with a total exposure of 135,000 km 2 sr yr. The strongest indication for an excess that we find, with a posttrial significance of 3.1 σ , is in the Centaurus region, as in our previous reports, and it extends down to lower energies than previously studied. We do not find any strong hints of excesses from any other region of the supergalactic plane at the same angular scale. In particular, our results do not confirm the reports by the Telescope Array Collaboration of excesses from two regions in the Northern Hemisphere at the edge of the field of view of the Pierre Auger Observatory. With a comparable integrated exposure over these regions, our results there are in good agreement with the expectations from an isotropic distribution.}, archive = {J_ApJ}, author = {A. Abdul Halim and P. Abreu and M. Aglietta and I. Allekotte and K. Almeida Cheminant and A. Almela and R. Aloisio and J. Alvarez-Muñiz and J. Ammerman Yebra and G.A. Anastasi and L. Anchordoqui and B. Andrada and S. Andringa and Anukriti and L. Apollonio and C. Aramo and P.R. Araújo Ferreira and E. Arnone and J.C. Arteaga Velázquez and P. Assis and G. Avila and E. Avocone and A. Bakalova and F. Barbato and A. Bartz Mocellin and J.A. Bellido and C. Berat and M.E. Bertaina and G. Bhatta and M. Bianciotto and P.L. Biermann and V. Binet and K. Bismark and T. Bister and J. Biteau and J. Blazek and C. Bleve and J. Blümer and M. Boháčová and D. Boncioli and C. Bonifazi and L. Bonneau Arbeletche and N. Borodai and J. Brack and P.G. Brichetto Orchera and F.L. Briechle and A. Bueno and S. Buitink and M. Buscemi and M. Büsken and A. Bwembya and K.S. Caballero-Mora and S. Cabana-Freire and L. Caccianiga and R. Caruso and A. Castellina and F. Catalani and G. Cataldi and L. Cazon and M. Cerda and A. Cermenati and J.A. Chinellato and J. Chudoba and L. Chytka and R.W. Clay and A.C. Cobos Cerutti and R. Colalillo and A. Coleman and M.R. Coluccia and R. Conceição and A. Condorelli and G. Consolati and M. Conte and F. Convenga and D. Correia dos Santos and P.J. Costa and C.E. Covault and M. Cristinziani and C.S. Cruz Sanchez and S. Dasso and K. Daumiller and B.R. Dawson and R.M. de Almeida and J. de Jesús and S.J. de Jong and J.R.T. de Mello Neto and I. De Mitri and J. de Oliveira and D. de Oliveira Franco and F. de Palma and V. de Souza and B.P. de Souza de Errico and E. De Vito and A. Del Popolo and O. Deligny and N. Denner and L. Deval and A. di Matteo and M. Dobre and C. Dobrigkeit and J.C. D’Olivo and L.M. Domingues Mendes and Q. Dorosti and J.C. dos Anjos and R.C. dos Anjos and J. Ebr and F. Ellwanger and M. Emam and R. Engel and I. Epicoco and M. Erdmann and A. Etchegoyen and C. Evoli and H. Falcke and J. Farmer and G. Farrar and A.C. Fauth and N. Fazzini and F. Feldbusch and F. Fenu and A. Fernandes and B. Fick and J.M. Figueira and A. Filipčič and T. Fitoussi and B. Flaggs and T. Fodran and T. Fujii and A. Fuster and C. Galea and C. Galelli and B. García and C. Gaudu and H. Gemmeke and F. Gesualdi and A. Gherghel-Lascu and P.L. Ghia and U. Giaccari and J. Glombitza and F. Gobbi and F. Gollan and G. Golup and M. Gómez Berisso and P.F. Gómez Vitale and J.P. Gongora and J.M. González and N. González and I. Goos and D. Góra and A. Gorgi and M. Gottowik and T.D. Grubb and F. Guarino and G.P. Guedes and E. Guido and L. Gülzow and S. Hahn and P. Hamal and M.R. Hampel and P. Hansen and D. Harari and V.M. Harvey and A. Haungs and T. Hebbeker and C. Hojvat and J.R. Hörandel and P. Horvath and M. Hrabovský and T. Huege and A. Insolia and P.G. Isar and P. Janecek and V. Jilek and J.A. Johnsen and J. Jurysek and K.-H. Kampert and B. Keilhauer and A. Khakurdikar and V.V. Kizakke Covilakam and H.O. Klages and M. Kleifges and F. Knapp and J. Köhler and N. Kunka and B.L. Lago and N. Langner and M.A. Leigui de Oliveira and Y. Lema-Capeans and A. Letessier-Selvon and I. Lhenry-Yvon and L. Lopes and L. Lu and Q. Luce and J.P. Lundquist and A. Machado Payeras and M. Majercakova and D. Mandat and B.C. Manning and P. Mantsch and S. Marafico and F.M. Mariani and A.G. Mariazzi and I.C. Mariş and G. Marsella and D. Martello and S. Martinelli and O. Martínez Bravo and M.A. Martins and H.-J. Mathes and J. Matthews and G. Matthiae and E. Mayotte and S. Mayotte and P.O. Mazur and G. Medina-Tanco and J. Meinert and D. Melo and A. Menshikov and C. Merx and S. Michal and M.I. Micheletti and L. Miramonti and S. Mollerach and F. Montanet and L. Morejon and C. Morello and K. Mulrey and R. Mussa and W.M. Namasaka and S. Negi and L. Nellen and K. Nguyen and G. Nicora and M. Niechciol and D. Nitz and D. Nosek and V. Novotny and L. Nožka and A. Nucita and L.A. Núñez and C. Oliveira and M. Palatka and J. Pallotta and S. Panja and G. Parente and T. Paulsen and J. Pawlowsky and M. Pech and J. Pekala and R. Pelayo and L.A.S. Pereira and E.E. Pereira Martins and J. Perez Armand and C. Pérez Bertolli and L. Perrone and S. Petrera and C. Petrucci and T. Pierog and M. Pimenta and M. Platino and B. Pont and M. Pothast and M. Pourmohammad Shahvar and P. Privitera and M. Prouza and A. Puyleart and S. Querchfeld and J. Rautenberg and D. Ravignani and J.V. Reginatto Akim and M. Reininghaus and J. Ridky and F. Riehn and M. Risse and V. Rizi and W. Rodrigues de Carvalho and E. Rodriguez and J. Rodriguez Rojo and M.J. Roncoroni and S. Rossoni and M. Roth and E. Roulet and A.C. Rovero and P. Ruehl and A. Saftoiu and M. Saharan and F. Salamida and H. Salazar and G. Salina and J.D. Sanabria Gomez and F. Sánchez and E.M. Santos and E. Santos and F. Sarazin and R. Sarmento and R. Sato and P. Savina and C.M. Schäfer and V. Scherini and H. Schieler and M. Schimassek and M. Schimp and D. Schmidt and O. Scholten and H. Schoorlemmer and P. Schovánek and F.G. Schröder and J. Schulte and T. Schulz and S.J. Sciutto and M. Scornavacche and A. Segreto and S. Sehgal and S.U. Shivashankara and G. Sigl and G. Silli and O. Sima and K. Simkova and F. Simon and R. Smau and R. Šmída and P. Sommers and J.F. Soriano and R. Squartini and M. Stadelmaier and S. Stanič and J. Stasielak and P. Stassi and S. Strähnz and M. Straub and T. Suomijärvi and A.D. Supanitsky and Z. Svozilikova and Z. Szadkowski and F. Tairli and A. Tapia and C. Taricco and C. Timmermans and O. Tkachenko and P. Tobiska and C.J. Todero Peixoto and B. Tomé and Z. Torrès and A. Travaini and P. Travnicek and C. Trimarelli and M. Tueros and M. Unger and L. Vaclavek and M. Vacula and J.F. Valdés Galicia and L. Valore and E. Varela and A. Vásquez-Ramírez and D. Veberič and C. Ventura and I.D. Vergara Quispe and V. Verzi and J. Vicha and J. Vink and S. Vorobiov and C. Watanabe and A.A. Watson and A. Weindl and L. Wiencke and H. Wilczyński and D. Wittkowski and B. Wundheiler and B. Yue and A. Yushkov and O. Zapparrata and E. Zas and D. Zavrtanik and M. Zavrtanik and The Pierre Auger Collaboration}, doi = {10.3847/1538-4357/adbdc5}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {123}, shortjournal = {The Astrophys. J.}, title = {The distribution of ultrahigh-energy cosmic rays along the supergalactic plane measured at the pierre auger observatory}, volume = {984}, year = {2025}, }
• (2025). The redshift evolution of the MBH–M* scaling relation: New insights from cosmological simulations and semianalytic models. ApJ, 984(2), 122. (www)

  @article{ , abstract = {We study the coevolution of black holes (BHs) and their host galaxies in the A STRID and TNG300 cosmological simulations and the D ARK S AGE semianalytic model (SAM), focusing on the evolution of the BH mass–stellar mass ( M BH – M * ) relation. Due to differences in the adopted subgrid modeling of BH seeding, dynamics, and feedback, the models differ in their predicted redshift evolution of the M BH – M * relation. We find that it is the interplay between the star formation rate (SFR) and the black hole accretion rate (BHAR) that drives the evolution of the mean relation. We define a quantity { \mathcal R } , the ratio between the specific BHAR and SFR (i.e., { \mathcal R }\,\equiv \, sBHAR/sSFR), and demonstrate that it is { \mathcal R } that governs the evolution of individual sources in the M BH – M * plane. The efficiency of BH growth versus stellar mass growth in the sSFR–sBHAR plane reflects the partitioning of gas between fueling star formation versus BH accretion. This partitioning depends on the implementation of BH dynamics and the nature of how black hole feedback quenches galaxies. In the cosmological simulations (A STRID and TNG300 ), the BHAR and SFR are intrinsically linked, resulting in a tight M BH – M * correlation, while the D ARK S AGE SAM produces a significantly larger scatter. We discuss these results in the context of recently discovered overmassive BHs and massive quenched galaxies at high redshift by the James Webb Space Telescope.}, archive = {J_ApJ}, author = {Shashank Dattathri and Priyamvada Natarajan and Antonio J. Porras-Valverde and Colin J. Burke and Nianyi Chen and Tiziana Di Matteo and Yueying Ni}, doi = {10.3847/1538-4357/adbeef}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {122}, shortjournal = {The Astrophys. J.}, title = {The redshift evolution of the MBH–M* scaling relation: New insights from cosmological simulations and semianalytic models}, volume = {984}, year = {2025}, }
• (2025). RUBIES: JWST/NIRSpec confirmation of an infrared-luminous, broad-line little red dot with an ionized outflow. ApJ, 984(2), 121. (www)

  @article{ , abstract = {The JWST discovery of "little red dots" (LRDs) is reshaping our picture of the early Universe, yet the physical mechanisms driving their compact size and UV-optical colors remain elusive. Here, we report an unusually bright LRD ( z spec = 3.1) observed as part of the RUBIES program. This LRD exhibits broad emission lines (FWHM ∼ 4000 km s −1 ), a blue UV continuum, a clear Balmer break, and a red continuum sampled out to rest-frame 4 μ m with MIRI. We develop a new joint galaxy and active galactic nucleus (AGN) model within the Prospector Bayesian inference framework and perform spectrophotometric modeling using NIRCam, MIRI, and NIRSpec/Prism observations. Our fiducial model reveals a M * ∼ 10 9 M ⊙ galaxy alongside a dust-reddened AGN driving the optical emission. Explaining the rest-frame optical color as a reddened AGN requires A V ≳ 3, suggesting that a great majority of the accretion disk energy is reradiated as dust emission. Yet, despite clear AGN signatures, we find a surprising lack of hot torus emission, which implies that either the dust emission in this object must be cold, or the red continuum must instead be driven by a massive, evolved stellar population of the host galaxy—seemingly inconsistent with the high-EW broad lines (H α rest-frame EW ∼ 800 Å). The widths and luminosities of Pa- β , Pa- δ , Pa- γ , and H α imply a modest black hole mass of M BH ∼ 10 8 M ⊙ . Additionally, we identify a narrow blueshifted He i λ 1.083 μ m absorption feature in NIRSpec/G395M spectra, signaling an ionized outflow with kinetic energy up to ∼1% the luminosity of the AGN. The low redshift of RUBIES-BLAGN-1, combined with the depth and richness of the JWST imaging and spectroscopic observations, provides a unique opportunity to build a physical model for these so-far mysterious LRDs, which may prove to be a crucial phase in the early formation of massive galaxies and their supermassive black holes.}, archive = {J_ApJ}, author = {Bingjie Wang and Anna de Graaff and Rebecca L. Davies and Jenny E. Greene and Joel Leja and Gabriel B. Brammer and Andy D. Goulding and Tim B. Miller and Katherine A. Suess and Andrea Weibel and Christina C. Williams and Rachel Bezanson and Leindert A. Boogaard and Nikko J. Cleri and Michaela Hirschmann and Harley Katz and Ivo Labbé and Michael V. Maseda and Jorryt Matthee and Ian McConachie and Rohan P. Naidu and Pascal A. Oesch and Hans-Walter Rix and David J. Setton and Katherine E. Whitaker}, doi = {10.3847/1538-4357/adc1ca}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {121}, shortjournal = {The Astrophys. J.}, title = {RUBIES: JWST/NIRSpec confirmation of an infrared-luminous, broad-line little red dot with an ionized outflow}, volume = {984}, year = {2025}, }
• (2025). Revisiting the group-dominant elliptical NGC 5044 in the radio band: Continuum emission and detection of h i absorption. ApJ, 984(2), 120. (www)

  @article{ , abstract = {We present new MeerKAT L -band (continuum and H i ) and upgraded Giant Metrewave Radio Telescope (300–850 MHz) observations of the archetypal cool-core group-dominant early-type galaxy NGC 5044. Our new continuum images reveal diffuse, steep spectrum ( {\alpha }_{0.99\,{\rm{GHz}}}^{1.56\,{\rm{GHz}}}=-1.53\pm 0.6 ) radio emission extending about 25 kpc around the unresolved radio core. The observed radio emission overlaps the known X-ray cavities but is not confined to them. We also find the first direct evidence of neutral atomic gas in NGC 5044, in the form of a 3.8 σ significant two-component H i absorption line seen against the emission of the active nucleus. The peak velocities are well correlated with the previously reported CO(2–1) absorption, but the H i lines are moderately broader, spanning velocities from 265 to 305 km s −1 . We do not detect H i emission but place an upper limit of M H i < 5.4 × 10 7 M ⊙ in the central 15'' (2.2 kpc) of the galaxy. This is significantly less than the estimated molecular gas content and implies a molecular-to-atomic mass ratio of  >∼1.7:1, consistent with these gas phases forming through cooling from the hot intra-group medium. We also constrain the spin temperature to T spin ≤ 950 K, indicating that the detected H i is in the cold neutral phase.}, archive = {J_ApJ}, author = {Kamlesh Rajpurohit and Tirna Deb and Konstantinos Kolokythas and Kshitij Thorat and Ewan O’Sullivan and Gerrit Schellenberger and Laurence P. David and Jan M. Vrtilek and Simona Giacintucci and William Forman and Christine Jones and Mpati Ramatsoku}, doi = {10.3847/1538-4357/adc1cb}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {120}, shortjournal = {The Astrophys. J.}, title = {Revisiting the group-dominant elliptical NGC 5044 in the radio band: Continuum emission and detection of h i absorption}, volume = {984}, year = {2025}, }
• (2025). High-frequency fast radio burst search of nearby star-forming galaxies m77 and m82. ApJ, 984(2), 119. (www)

  @article{ , abstract = {The astrophysical origins of fast radio bursts (FRBs) are still unknown, but magnetars are a strong candidate for producing at least some FRBs. To investigate the magnetar progenitor model, we conducted a deep search of M77 and M82, two nearby galaxies with high star formation rates that could potentially harbor large magnetar populations. Using one of the 34 m dishes in the Deep Space Network, we observed the two galaxies at 8.4 GHz for about 100 hr each. At this observing frequency, we are unaffected by the potentially extreme temporal broadening caused by multipath scattering in the turbulent inner regions of the galaxies. We do not detect any FRBs from either galaxy above a fluence detection threshold of {F}_{{\rm{\min }}}=1.3\,{\rm{Jy}}\,{\rm{ms}} , which corresponds to an isotropic energy equivalent of {E}_{{\rm{iso,min}}}=2.7\times 1{0}^{36}\,{\rm{erg}} for M77 and {E}_{{\rm{iso,min}}}=1.7\times 1{0}^{35}\,{\rm{erg}} for M82. Based on the nondetections, we set a 95% upper limit to the 8.4 GHz burst rate of R 95 = 273 yr −1 and R 95 = 233 yr −1 for M77 and M82, respectively. By estimating the magnetar population in each galaxy, we set an upper limit to the burst rate per magnetar of {r}_{{\rm{\max }}}\approx 1\,{{\rm{magnetar}}}^{-1}\,{{\rm{yr}}}^{-1} . Unlike previous searches of these galaxies at frequencies of ν ≲ 1.5 GHz, our results give a scattering-independent limit to the burst rate.}, archive = {J_ApJ}, author = {Robert S. Wharton and Walid A. Majid and Myles B. Sherman and Liam Connor and Jonathon Kocz and Wenbin Lu and Aaron B. Pearlman and Thomas A. Prince and Vikram Ravi}, doi = {10.3847/1538-4357/adc303}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {119}, shortjournal = {The Astrophys. J.}, title = {High-frequency fast radio burst search of nearby star-forming galaxies m77 and m82}, volume = {984}, year = {2025}, }
• (2025). Discovery of a new flaring class in GRS 1915+105 using AstroSat. ApJ, 984(2), 118. (www)

  @article{ , abstract = {The highly variable black hole X-ray binary GRS 1915+105 has shown many flaring classes when the source oscillates between the high soft state (HS) and the hard intermediate state with a transition time of less than 10 s. The X-ray flux is anticorrelated with the hardness ratio (HR2) during these X-ray flaring classes. We have analyzed Astrosat/Large Area X-ray Proportional Counter and Soft X-ray Telescope data and report here a new X-ray flaring class named η class when the source oscillates between two HS states (the power-law index is always greater than 4) with transition time around 50 s. The X-ray flux is correlated with the hardness ratio. This class is quasi-regular, and we have detected high-frequency quasiperiodic oscillations around 70 Hz during this new flaring class. The accretion rate changes by a factor of 3 over the burst cycle. We report here the results of our extensive study of spectral and timing characteristics of this new class.}, archive = {J_ApJ}, author = {Ruchika Dhaka and J. S. Yadav and Ranjeev Misra and Pankaj Jain}, doi = {10.3847/1538-4357/adc381}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {118}, shortjournal = {The Astrophys. J.}, title = {Discovery of a new flaring class in GRS 1915+105 using AstroSat}, volume = {984}, year = {2025}, }
• (2025). StAGE: Stellar archaeology-driven galaxy evolution. ApJ, 984(2), 117. (www)

  @article{ , abstract = {We build a semiempirical framework of galaxy evolution (dubbed StAGE ) firmly grounded on stellar archaeology. The latter provides data-driven prescriptions that, on a population statistical ground, allow us to define the age and the star formation history for the progenitors of quiescent galaxies (QGs). We exploit StAGE to compute the cosmic star formation rate (SFR) density contributed by the progenitors of local QGs, and show it to remarkably agree with that estimated for high- z dusty star-forming galaxies which are faint/dark in the near-infrared (NIR), so pointing toward a direct progenitor-descendant connection among these galaxy populations. Furthermore, we argue that by appropriately correcting the observed stellar mass density by the contribution of such NIR-dark progenitors, StAGE recovers a SFR density which is consistent with direct determinations from UV/IR/radio surveys, so substantially alleviating a longstanding tension. Relatedly, we also show how StAGE can provide the average mass and metal assembly history of QGs, and their redshift-dependent statistics. Focusing on the supermassive black holes (BHs) hosted by massive QGs, we exploit StAGE to reconstruct the average BH mass assembly history, the cosmic BH accretion rate density as a function of redshift, and the evolution of the Magorrian-like relationship between the relic stellar and BH masses. All in all, StAGE may constitute a valuable tool to understand via a data-driven, easily expandable, and computationally low-cost approach the coevolution of QGs and of their hosted supermassive BHs across cosmic times.}, archive = {J_ApJ}, author = {Michele Bosi and Andrea Lapi and Lumen Boco and Carlos A. Alvarez and Marcos M. Cueli and Giovanni Antinozzi and Meriem Behiri and Marika Giulietti and Marcella Massardi and Mario Spera and Alessandro Bressan and Carlo Baccigalupi and Luigi Danese}, doi = {10.3847/1538-4357/adc721}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {117}, shortjournal = {The Astrophys. J.}, title = {StAGE: Stellar archaeology-driven galaxy evolution}, volume = {984}, year = {2025}, }
• (2025). Detecting the 21 cm signal from the cosmic dark ages. ApJ, 984(2), 116. (www)

  @article{ , abstract = {The cosmic "dark ages" is the period between the last scattering of the cosmic microwave background and the appearance of the first luminous sources, spanning redshifts 1100 ≳ z ≳ 30. The only way to observe this period is by examining the 21 cm hyperfine transition line of neutral hydrogen H i , which—given the high redshifts (and hence long wavelengths)—must be observed from outside Earth's ionosphere. Given the faintness of the signal, concepts for a radio array on the lunar far side (where large collecting areas can be deployed and radio frequency interference is minimal) have been proposed, like FarView or FARSIDE, but designs are still in the preliminary stages. This paper studies multiple aspects of array design to determine the impact of different design decisions on sensitivity to the dark ages 21 cm power spectrum. We do so by using the sensitivity package 21cmSense to model and simulate various array configurations. We present a fiducial design based on a modification of the FarView concept, which consists of a collecting area of ∼2.5 km 2 with 82,944 tightly packed dual-polarization dipoles grouped into 5184 correlated elements, or subarrays, delivering a >10 σ detection of the z = 30 signal with a 5 yr lifetime. We find that, beyond mere collecting area, the most important factor in achieving this sensitivity is the presence of very short baselines that can only be realized with small, closely packed antennas.}, archive = {J_ApJ}, author = {Willow Smith and Jonathan C. Pober}, doi = {10.3847/1538-4357/adc72c}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {116}, shortjournal = {The Astrophys. J.}, title = {Detecting the 21 cm signal from the cosmic dark ages}, volume = {984}, year = {2025}, }
• (2025). The spin measurement of the black hole SLX 1746-331 using insight-HXMT observations. ApJ, 984(2), 115. (www)

  @article{ , abstract = {We present an X-ray spectral analysis of a black hole X-ray binary, SLX 1746-331, during the 2023 outburst using five Insight-HXMT observations. We jointly use the reflection model relxillcp and the general relativistic thermal thin disk model kerrbb to fit the spectra from 2 to 100 keV. By jointly fitting the five spectra, we constrain the black hole mass to be M = 5.8 ± 0.3 M ⊙ and the dimensionless spin parameter to be {a}_{* }=0.8{8}_{-0.02}^{+0.01} (90% statistical confidence). The reflection model shows that SLX 1746-331 is a high-inclination system with the inclination angle i=63\mathop{.}\limits^{{\rm{^\circ }}}{7}_{-1.0}^{+1.3} , and the accretion disk has a density {\rm{log}}N\sim 16\,{{\rm{cm}}}^{-3} . In addition, with the different reflection model relxilllp , which assumes a lamppost geometry corona, we still obtain similar results.}, archive = {J_ApJ}, author = {Jiashi Chen and Wei Wang}, doi = {10.3847/1538-4357/adc926}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {115}, shortjournal = {The Astrophys. J.}, title = {The spin measurement of the black hole SLX 1746-331 using insight-HXMT observations}, volume = {984}, year = {2025}, }
• (2025). Spatially resolved kinematics of post-starburst galaxies. ApJ, 984(2), 114. (www)

  @article{ , abstract = {Star-forming galaxies can reach quiescence via rapid transition through merger-triggered starbursts that consequently affect both their kinematics and star formation rates. In this work, we analyze the spatially resolved kinematics of 89 post-starburst galaxies (PSBs) with data from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey and place them in context with star-forming galaxies (SFGs) and early-type galaxies (ETGs) to study the impact of merger history on galaxy kinematics. We measure the specific angular momentum to characterize them as slow or fast rotators. We find that the MaNGA PSB sample has ~6% slow rotators, which is less than the ~14% slow rotators in the ATLAS 3D ETG sample and ~20% slow rotators in the MaNGA ETGs, and more than the ~3.5% slow rotators in the MaNGA SFGs. This implies that for PSBs to evolve into ETGs, they must still lose some angular momentum. While ETGs with higher stellar mass tend to be slow rotators, PSBs do not follow this trend. We find significant correlations between specific angular momentum and mass-weighted age for the SFG and ETG samples, but do not see any significant trends within the short PSB phase. These results indicate that significant evolution in angular momentum must continue to take place as the galaxy ages after the PSB phase. For PSBs to evolve directly into ETGs, they must undergo dry mergers to shed excess angular momentum without causing further epochs of star formation.}, archive = {J_ApJ}, author = {Bhavya Pardasani and K. Decker French}, doi = {10.3847/1538-4357/ada7f6}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {114}, shortjournal = {The Astrophys. J.}, title = {Spatially resolved kinematics of post-starburst galaxies}, volume = {984}, year = {2025}, }
• (2025). Reversals of toroidal magnetic field in local shearing box simulations of accretion disk with a hot corona. ApJ, 984(2), 113. (www)

  @article{ , abstract = {The presence of a hot corona above the accretion disk can have important consequences for the evolution of magnetic fields and the Shakura–Sunyaev viscosity parameter α in such a strongly coupled system. In this work, we have performed three-dimensional magnetohydrodynamical shearing-box numerical simulations of an accretion disk with a hot corona above the cool disk. Such a two-layer, piecewise isothermal system is vertically stratified under linear gravity, and initial conditions here include a strong azimuthal magnetic field with a ratio between the thermal and magnetic pressures being of order unity in the disk region. Instabilities in this magnetized system lead to the generation of turbulence, which, in turn, governs the further evolution of magnetic fields in a self-sustaining manner. Remarkably, the mean toroidal magnetic field undergoes a complete reversal in time by changing its sign, and it is predominantly confined within the disk. This is a rather unique class of evolution of the magnetic field that has not been reported earlier. Solutions of mean magnetic fields here are thus qualitatively different from the vertically migrating dynamo waves that are commonly seen in previous works, which model a single layer of an isothermal gas. Effective α is found to have values between 0.01 and 0.03. We have also make a comparison between models with Smagorinsky and explicit schemes for the kinematic viscosity ( ν ). In some cases with an explicit ν , we find a burst-like temporal behavior in α .}, archive = {J_ApJ}, author = {Nishant K. Singh and Arunima Ajay and S. R. Rajesh}, doi = {10.3847/1538-4357/adbf02}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {113}, shortjournal = {The Astrophys. J.}, title = {Reversals of toroidal magnetic field in local shearing box simulations of accretion disk with a hot corona}, volume = {984}, year = {2025}, }
• (2025). Thirty-two new bright ZZ ceti stars from TESS: Adding cycles 4 and 5. ApJ, 984(2), 112. (www)

  @article{ , abstract = {Analyzing all 120 s and 20 s light curves obtained by the TESS satellite up to Sector 69—the end of the fifth year of observations—for all known white dwarfs and white dwarf candidates up to G = 17.5 mag, we report the discovery of 32 new pulsating DA white dwarf stars. For all objects, we obtained the period spectra and performed a seismological analysis using full evolutionary models to estimate the structural parameters, such as effective temperature, stellar mass, and hydrogen envelope mass. The median stellar mass for the pulsators from asteroseismology is 0.609 M ⊙ , in agreement with the median value of photometric and spectroscopic determinations, 0.602 M ⊙ , excluding the low and extremely low mass objects. Finally, we found rotational-splitting multiplets for nine stars, which led to rotation periods between 4 hr and 1 day.}, archive = {J_ApJ}, author = {Alejandra D. Romero and S. O. Kepler and Gabriela Oliveira da Rosa and J. J. Hermes}, doi = {10.3847/1538-4357/adc113}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {112}, shortjournal = {The Astrophys. J.}, title = {Thirty-two new bright ZZ ceti stars from TESS: Adding cycles 4 and 5}, volume = {984}, year = {2025}, }
• (2025). Improving pulsar timing precision with single pulse fluence clustering. ApJ, 984(2), 111. (www)

  @article{ , abstract = {Traditional pulsar timing techniques involve averaging large numbers of single pulses to obtain a high signal-to-noise ratio (S/N) profile, which is cross-correlated with a template to measure a time of arrival (TOA). However, the morphology of individual single pulses varies greatly due to pulse jitter, and pulses of different fluence contribute differently to the S/N of the pulse average. Our study proposes a method that accounts for these variations by identifying a range of "states" and timing each separately. We selected two 1 hr observations of PSR J2145−0750, each in a different frequency band, with the Green Bank Telescope. We normalized the pulse amplitudes using the dynamic spectrum to account for scintillation effects and probed different excision algorithms to reduce radio-frequency interference. We then measured four pulse parameters (amplitude, position, width, and energy) to classify the single pulses using automated clustering algorithms. For each cluster, we calculated an average pulse profile and template and used both to obtain a TOA and TOA error. Finally, we computed the weighted average TOA and TOA error, the latter as a metric of the total timing precision for the epoch. The TOA is shifted relative to the one obtained without clustering, and we can estimate the shift with this weighting using the same data. For the 820 and 1400 MHz bands, we obtained TOA uncertainties of 0.057 and 0.46 μ s, compared to 0.066 and 0.74 μ s when no clustering is applied. We conclude that tailoring this method could help improve the timing precision for certain bright pulsars in NANOGrav's data set.}, archive = {J_ApJ}, author = {Sofia V. Sosa Fiscella and Michael T. Lam and Maura A. McLaughlin}, doi = {10.3847/1538-4357/adc1c2}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {111}, shortjournal = {The Astrophys. J.}, title = {Improving pulsar timing precision with single pulse fluence clustering}, volume = {984}, year = {2025}, }
• (2025). Jet-mode feedback in NGC 5972: Insights from resolved MUSE, GMRT, and VLA observations. ApJ, 984(2), 110. (www)

  @article{ , abstract = {NGC 5972, a Voorwerp galaxy, features a helical-shaped extended emission-line region (EELR) with a radius >10 kpc and an S-shaped radio structure spanning about 470 kpc. We use the Very Large Telescope, Multi Unit Spectroscopic Explorer, Giant Metrewave Radio Telescope, and Very Large Array (VLA) to study the stellar and ionized gas kinematics and how the radio jet influences the gas in the galaxy. Our sensitive radio observations detect the southern jet for the first time, roughly coinciding with the southern EELR. The VLA images show a continuous inner jet connected to the outer east–west lobe, confirming the jet origin of the radio emission. Our kinematic analysis shows spatial correlations between the radio jet and the outflowing gas, supporting the jet-driven feedback mechanism. More interestingly, we observe enhanced velocity dispersion in the perpendicular direction along with a shell-like structure. Our Baldwin–Phillips–Telervich analysis shows that the [O III ] emission overlapping with the radio jet is consistent with the shock+precursor model, whereas in the perpendicular region, a pure shock model fits well with the observations, indicating jet-induced shocks. Radio observations indicate episodic AGN activity characterized by surface brightness and spectral index discontinuities. Overall, based on our findings, we propose a jet-driven feedback mechanism as one of the key factors in the formation of the EELR in NGC 5972. Future high-resolution radio observations will be crucial to further investigate the origin of the EELR and quantify the extent to which the jet influences its formation and evolution.}, archive = {J_ApJ}, author = {Arshi Ali and Biny Sebastian and Darshan Kakkad and Sasikumar Silpa and Preeti Kharb and Christopher P. O’Dea and Mainak Singha and K. Rubinur and Stefi A. Baum and Omkar Bait and Sravani Vaddi and Sushma Kurapati}, doi = {10.3847/1538-4357/adc38d}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {110}, shortjournal = {The Astrophys. J.}, title = {Jet-mode feedback in NGC 5972: Insights from resolved MUSE, GMRT, and VLA observations}, volume = {984}, year = {2025}, }
• (2025). Gas transfer between the inner 3 kpc disk and the galactic central molecular zone. ApJ, 984(2), 109. (www)

  @article{ , abstract = {We uncovered a more tilted molecular gas structure with highly negative velocities located near the dust lane. Our observations show that the approaching gas flows from the overshoot process are captured by the gravitational potential of the bar and then flow toward the Galactic central molecular zone (CMZ) through the bar channel. The recycled gas from the overshoot effect, in conjunction with freshly accreted gas from the inner 3 kpc disk, accumulates significantly near the {R}_{{\rm{GC}}}\sim \frac{1}{2}{R}_{{\rm{bar}}} and {R}_{{\rm{GC}}}\sim \frac{2}{3}{R}_{{\rm{bar}}} regions by adopting a bar length of ∼3.2–3.4 kpc. Importantly, within these regions, there are frequent collisions and substantial angular momentum exchanges between gas flows with different trajectories. In this scenario, the dissipation processes arising from interactions between colliding flows, together with the varying torques induced by the nonaxisymmetric bar, effectively transfer the angular momentum of viscous gas outward, thereby driving the molecular gas to settle into the CMZ within about three orbital periods. A long-term gas inflow with an average rate of ≳1.1 M ⊙ yr −1 , coupled with intense transient accretion events that exceed the average rate by several times due to the overshoot effect, significantly regulates the gas distribution, physical properties, and dynamical evolution of the CMZ. These new findings provide robust observational evidence for elucidating the intricate dynamics of molecular gas flows toward the CMZ. Our observations suggest that gas dynamics have a significant impact on the secular evolution of both the Milky Way and the extragalactic gas-rich galaxies.}, archive = {J_ApJ}, author = {Yang Su and Shiyu Zhang and Yan Sun and Ji Yang and Fujun Du and Min Fang and Qing-Zeng Yan and Shaobo Zhang and Zhiwei Chen and Xuepeng Chen and Xin Zhou and Lixia Yuan and Yuehui Ma}, doi = {10.3847/1538-4357/adc38e}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {109}, shortjournal = {The Astrophys. J.}, title = {Gas transfer between the inner 3 kpc disk and the galactic central molecular zone}, volume = {984}, year = {2025}, }
• (2025). Constraining extra mixing during the main sequence: Whatever depletes lithium does not touch beryllium*. ApJ, 984(2), 108. (www)

  @article{ , abstract = {Measurements of lithium (Li) abundances in solar-type stars have shown that standard models of stellar evolution are incapable of explaining the observed depletion as a function of stellar age. Beryllium (Be) is one of the lightest elements that can be measured in stellar photospheres and can be burned at relatively low temperatures. Studying its abundances as a function of stellar age can provide important constraints to stellar mixing models because the level of depletion as a function of time will indicate how deep the photospheric material must be dredged to explain the observed abundances. In an effort to provide the most stringent constraints for nonstandard stellar mixing models, we observed a sample of solar twins and concomitantly analyzed their Li and Be abundances. Unlike what is typically observed for Li, we found that Be does not decrease as a function of stellar age along the main sequence, constraining models that predict the burning of both materials. Based on our data, models that invoke convective overshoot and convective settling are preferred over typical rotationally induced mixing models, as the later burn Be in excess while the former do not. Previous works also proposed mixing due to gravity waves as a possible explanation for observed abundances, which can fit our data as well. Furthermore, based on our solar twins, Be depletion likely happens within the first ∼1 Gyr. We also confirm previous findings of an increase in Be abundance as a function of metallicity, indicative of galactic production via cosmic-ray spallation.}, archive = {J_ApJ}, author = {Henrique Reggiani and Jhon Yana Galarza and Diego Lorenzo-Oliveira and Sofia Covarrubias and Micaela Oyague and Rita Valle and Julio Chanamé}, doi = {10.3847/1538-4357/adc43e}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {108}, shortjournal = {The Astrophys. J.}, title = {Constraining extra mixing during the main sequence: Whatever depletes lithium does not touch beryllium*}, volume = {984}, year = {2025}, }
• (2025). μ-GLANCE: A novel technique to detect chromatically and achromatically lensed gravitational-wave signals. ApJ, 984(2), 107. (www)

  @article{ , abstract = {Gravitational microlensing in the wave-optics (WO) regime occurs when the Schwarzschild radius of a lensing object is comparable to or smaller than the wavelength of incoming gravitational waves (GWs), producing chromatic amplitude and phase modulations. In contrast, geometric-optics effects happen when wavelength is much smaller than the lensing object, leading to frequency-independent amplifications and phase shifts. GWs can undergo both effects of lensing owing to interactions with objects of different scales. To detect and characterize the WO features from a lensed GW, we have developed a novel method, μ -GLANCE (Micro-Gravitational Lensing Authenticator using Non-modeled Cross-correlation Exploration). In this technique, we calculate the cross-correlation between the residuals from different detectors. We assign a false-alarm rate to each potential WO microlensed candidate from a statistical viewpoint, depending on how many times the noise cross-correlation matches the strength of the residual cross-correlation of the candidate over a certain period of time. We show that for an event with a matched-filtering signal-to-noise ratio close to 30, a residual due to WO lensing with an amplitude about 10% of magnification μ ≈ 3.2 will start to show deviation from the noise distribution at more than a 68% confidence interval with the LIGO-Virgo-KAGRA sensitivity for the fourth observation run. This method provides the first technique to detect geometric-optics and WO effects from a WO microlensed GW without assuming any specific lensing model, and its application to the current and future GW data can identify events with both chromatic and achromatic lensed scenarios.}, archive = {J_ApJ}, author = {Aniruddha Chakraborty and Suvodip Mukherjee}, doi = {10.3847/1538-4357/adc578}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {107}, shortjournal = {The Astrophys. J.}, title = {μ-GLANCE: A novel technique to detect chromatically and achromatically lensed gravitational-wave signals}, volume = {984}, year = {2025}, }
• (2025). A closer look at the origin of LINER emission in later-type galaxies and its connection to evolved stars with a machine learning classification scheme. ApJ, 984(2), 106. (www)

  @article{ , abstract = {Identifying the dominant ionizing sources in galaxies is essential for understanding their formation and evolution. Traditionally, spectra are classified based on their dominant ionizing source using strong emission lines and Baldwin, Phillips, & Terlevich (BPT) diagrams. The ionizing source is traditionally determined by the emission line ratios using the BPT diagrams. Low-ionization nuclear emission-line regions (LINERs) are a class of ionizing mechanisms that is observationally identified but with a poorly understood origin, unlike the case of star-forming regions and active galactic nuclei (AGN). LINERs, typically found in early-type galaxies, are often associated with low-luminosity AGN activity but may also be powered by aging stellar populations, particularly post-asymptotic giant branch (p-AGB) stars. In this study, we employ a machine-learning-based encoder, spender , to analyze the full MaNGA integral field unit spectra and identify key spectral features of LINERs. By examining the continuum and line emission of these spaxels, our approach aims to uncover hidden patterns and better understand the dominant ionizing sources. We show in this work that the neural-network-based encoder was able identify LINER sources from the stellar continuum alone. The characteristics of the stellar population underlying LINER regions are consistent with evolved low-mass stars, implying that the source driving LINER emission is probably p-AGB stars rather than AGN activity.}, archive = {J_ApJ}, author = {Ahmad Nemer and Ivan Yu. Katkov and Joseph D. Gelfand and Changhyun Cho}, doi = {10.3847/1538-4357/adc57e}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {106}, shortjournal = {The Astrophys. J.}, title = {A closer look at the origin of LINER emission in later-type galaxies and its connection to evolved stars with a machine learning classification scheme}, volume = {984}, year = {2025}, }
• (2025). The evolving power spectrum for the light cone epoch of reionization 21 cm signal. ApJ, 984(2), 105. (www)

  @article{ , abstract = {The rapid evolution of the cosmological neutral hydrogen (H i ) distribution during the Epoch of Reionization (EoR) is imprinted along the line of sight (LoS) in the redshifted 21 cm signal due to the light cone (LC) effect. The LC EoR 21 cm signal ceases to be ergodic along the LoS, and the Fourier-transform-based three-dimensional power spectrum fails to capture the full two-point statistics. Several earlier studies have used the multifrequency angular power spectrum (MAPS) {{ \mathcal C }}_{\ell }({\nu }_{1},{\nu }_{2}) to overcome this limitation. However, we do not have a simple interpretation of {{ \mathcal C }}_{\ell }({\nu }_{1},{\nu }_{2}) in terms of comoving length scale, and the data volume is large. Here we introduce the evolving power spectrum (ePS) to quantify the two-point statistics of the LC EoR 21 cm signal. This has a simple interpretation in terms of redshift evolution and comoving length scales, and the binned ePS reduces the data volume by several orders of magnitude compared to MAPS. Considering simulations, we study the first three even angular multipoles of ePS to quantify the LoS anisotropy of the signal. We find that as reionization progresses, at large k (≥0.6 Mpc −1 ), P e 0 ( k , z ), the monopole moment decreases as \propto {\bar{x}}_{{\rm{H}}\,{\rm\small{I}}} , the mean neutral H i fraction, which, in principle, can be used to observationally determine the reionization history. Furthermore, P e 2 ( k , z ), the quadrupole moment, is negative at small k and positive at large k . We propose the binned ePS, which captures all of the information contained in MAPS, to quantify the full two-point statistics of the LC EoR 21 cm signal.}, archive = {J_ApJ}, author = {Suman Pramanick and Somnath Bharadwaj and Khandakar Md Asif Elahi and Rajesh Mondal}, doi = {10.3847/1538-4357/adc678}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {105}, shortjournal = {The Astrophys. J.}, title = {The evolving power spectrum for the light cone epoch of reionization 21 cm signal}, volume = {984}, year = {2025}, }
• (2025). The distance to the magellanic stream: Constraints from optical absorption along stellar sight lines. ApJ, 984(2), 104. (www)

  @article{ , abstract = {The Magellanic Stream is a large tail of neutral and ionized gas originating from tidal and hydrodynamical interactions between the Magellanic Clouds as they orbit the Milky Way (MW). It carries a significant gas reservoir that could impact the future evolution of the MW. Despite its importance, no direct observational constraints on the Stream's distance have been previously published. In this study, we analyze Very Large Telescope/Ultraviolet and Visual Echelle Spectrograph spectra of five blue horizontal branch stars in the MW halo located at distances ranging from 13 to 56 kpc near two regions of the Stream (near Stream longitudes of –79 ∘ and –98 ∘ ), with the aim of detecting Ca ii and Na i absorption. No Ca ii or Na i absorption is detected at Stream velocities in any of the individual spectra or in higher signal-to-noise stacks of the spectra. The resulting limits on the Ca ii absorption are significantly lower than the Ca ii columns measured in the Stream along extragalactic sight lines. These nondetections establish a firm lower distance limit of 42 kpc for one region of the Stream. For the other region, we set a firm lower limit of 20 kpc and a tentative lower limit of 55 kpc from the most distant star, but deeper spectra are needed to confirm this. Our results provide the first observational constraints on the gaseous Stream's distance.}, archive = {J_ApJ}, author = {Sapna Mishra and Andrew J. Fox and J. V. Smoker and Scott Lucchini and Elena D’Onghia}, doi = {10.3847/1538-4357/adc68a}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {104}, shortjournal = {The Astrophys. J.}, title = {The distance to the magellanic stream: Constraints from optical absorption along stellar sight lines}, volume = {984}, year = {2025}, }
• (2025). High-energy gamma-ray and neutrino emissions from interacting supernovae based on radiation hydrodynamic simulations: A case of SN 2023ixf. ApJ, 984(2), 103. (www)

  @article{ , abstract = {Recent observations of core-collapse supernovae revealed that the existence of dense circumstellar matter (CSM) around their progenitors is ubiquitous. Interaction of supernova ejecta with such a dense CSM is a potential production site of high-energy cosmic rays (CRs), gamma rays, and neutrinos. We estimate the gamma-ray and neutrino signals from SN 2023ixf, a core-collapse supernova occurred in a nearby galaxy M101, which exhibits signatures of the interaction with the confined, dense CSM. Using a radiation-hydrodynamic simulation model calibrated by the optical and ultraviolet observations of SN 2023ixf, we find that the CRs cannot be accelerated in the early phase because the sharp velocity jump at the shock disappears due to strong radiation pressure. Roughly 4 days after the explosion, the collisionless subshock is formed in the CSM, which enables the CR production and leads to gamma-ray and neutrino emissions. The shock sweeps up the entire dense CSM roughly 9 days after the explosion, which ceases the high-energy radiation. Based on this scenario, we calculate the gamma-ray and neutrino signals, which have a peak around 9 days after the explosion. We can constrain the CR production efficiency to be less than 10% by comparing our prediction to the Fermi Large Area Telescope upper limits. Future multimessenger observations with an enlarged sample of nearby supernovae will provide a better constraint on the CR production efficiency in the early phases of supernovae.}, archive = {J_ApJ}, author = {Shigeo S. Kimura and Takashi J. Moriya}, doi = {10.3847/1538-4357/adc716}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {103}, shortjournal = {The Astrophys. J.}, title = {High-energy gamma-ray and neutrino emissions from interacting supernovae based on radiation hydrodynamic simulations: A case of SN 2023ixf}, volume = {984}, year = {2025}, }
• (2025). Investigating the spectral nature of gigahertz-peaked spectra pulsar candidates. ApJ, 984(2), 102. (www)

  @article{ , abstract = {We report the measurements of low radio frequency spectra of 14 gigahertz-peaked spectra (GPS) pulsar candidates, between 300 and 700 MHz, using the upgraded Giant Metrewave Radio Telescope. Combining newly collected measurements with archival results, the spectral nature of each pulsar was examined using four different physical models: simple power law, broken power law, low-frequency turnover power law, and free–free thermal absorption. Based on this analysis, we confirm the GPS nature of five pulsars, three of them being new detections. In addition, one pulsar can be classified as having a broken power law spectrum, and we found the typical power-law spectra in four other cases. In the remaining four pulsars, the spectra showed tendencies of low-frequency turnover that require further investigations at lower frequency ranges. These results demonstrate the effectiveness of wideband measurements at low frequencies, below 1 GHz, in characterizing the spectral nature in pulsars. Our results also underline the need for more systematic theoretical studies to refine existing models and better interpret pulsar emission properties.}, archive = {J_ApJ}, author = {K. Rożko and J. Kijak and R. Basu and P. Dabhade and W. Lewandowski}, doi = {10.3847/1538-4357/adc726}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {102}, shortjournal = {The Astrophys. J.}, title = {Investigating the spectral nature of gigahertz-peaked spectra pulsar candidates}, volume = {984}, year = {2025}, }
• (2025). Measuring mass of gas in central galaxies using weak lensing and satellite kinematics in MOND. ApJ, 984(2), 101. (www)

  @article{ , abstract = {In Milgrom's MOdified Newtonian Dynamics (MOND) framework, the dynamical mass of a galaxy is fully determined by its baryonic matter distribution. Using this framework, we fit the distribution of cold and hot gas halos—focusing on the hot gas—around Sloan Digital Sky Survey central galaxies, utilizing weak lensing signals from the DECaLS survey. The central galaxies are classified into the total sample and the star-forming sample. Hot gas halo densities nearly follow Plummer's profile for both samples across all mass bins out to extended radii. We then demonstrate the rotation curves of the galaxy samples. Furthermore, the stellar fraction, M * /( M * + M g ), is between 0.3 and 0.8 in all mass bins of the star-forming sample, which is higher than in the total sample. Additionally, we use the satellite kinematics method in MOND to verify our findings from the weak lensing method. We find good agreement between the two methods, indicating that weak lensing signals reliably measure the dynamical mass of central galaxies and can constrain the distribution of missing baryons in galaxy clusters. Combining both methods, we discover a baryonic mass to line-of-sight velocity dispersion of satellites ( M b – σ s ) relation. More sophisticated models, such as Osipkov–Merritt anisotropy profiles, were found unnecessary, as simple isotropic or mildly radially anisotropic MOND models align well with the observed M b – σ s relation. Moreover, the isotropic model remains consistent with this relation even when considering external fields from large-scale structures.}, archive = {J_ApJ}, author = {Li Ma and Ziwen Zhang and Huiyuan Wang and Xufen Wu}, doi = {10.3847/1538-4357/adc728}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {101}, shortjournal = {The Astrophys. J.}, title = {Measuring mass of gas in central galaxies using weak lensing and satellite kinematics in MOND}, volume = {984}, year = {2025}, }
• (2025). The formation of direct collapse black holes at cosmic dawn and 21 cm global spectrum. ApJ, 984(2), 100. (www)

  @article{ , abstract = {JWST reveals numerous high- z galaxies and supermassive black holes (SMBHs), suggesting that stars and SMBH seeds formation at z ≳ 10 may be more efficient than previously derived. One popular SMBH seed scenario is the direct collapse black holes (DCBHs) formed in pristine atomic-cooling halos irradiated by nearby galaxies. Therefore, the efficient star formation likely facilitates the formation of DCBH. We calculate the first critical {k}_{{{\rm{H}}}_{2}}\unicode{8210}{k}_{{{\rm{H}}}^{-}} curves for DCBH formation under the influence of X-ray radiation using the one-zone model. We then build the UV luminosity function consistent with JWST observations and incorporate it into the model that calculates the DCBH-triggering probability. We confirm that enhanced star formation promotes the DCBH formation. However, the DCBH abundance n DCBH is significantly influenced by the X-ray radiation that is also related to star formation. Since the 21 cm global spectrum is also X-ray dependent, the 21 cm absorption depth \delta {T}_{b}^{{\rm{trough}}} at Cosmic Dawn encodes the DCBH abundance information. We provide a tentative trend in the n DCBH – \delta {T}_{{\rm{b}}}^{{\rm{trough}}} relation, which could be a useful guide. In our fiducial model, if \delta {T}_{b}^{{\rm{trough}}}\gtrsim -100 mK, then the DCBH is rather rare; if -150\,\mathrm{mK}\lesssim \delta {T}_{b}^{\mathrm{trough}}\lesssim -100 mK, {n}_{{\rm{DCBH}}}\sim { \mathcal O }(1{0}^{-2}-1{0}^{-3}) cMpc −3 (comoving Mpc −3 ), consistent with the HST/JWST observed SMBHs abundance at z ≳ 6; if \delta {T}_{b}^{{\rm{trough}}}\lesssim -150 mK, n DCBH can largely exceed { \mathcal O }(1{0}^{-2}) cMpc −3 . The 21 cm global spectrum observations will help to constrain the DCBH abundance.}, archive = {J_ApJ}, author = {Meng Zhang and Bin Yue and Yidong Xu and Andrea Ferrara}, doi = {10.3847/1538-4357/adc730}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {100}, shortjournal = {The Astrophys. J.}, title = {The formation of direct collapse black holes at cosmic dawn and 21 cm global spectrum}, volume = {984}, year = {2025}, }
• (2025). Reconstructing he i 10830 Å images using hα images through deep learning. ApJ, 984(2), 99. (www)

  @article{ , abstract = {He i 10830 Å, as an important spectrum line to diagnose the solar chromosphere and corona, has had consistent observations within the past two decades. This study aims to reconstruct synthetic He i 10830 Å images, addressing the limited availability of historical data compared to the extensive record of H α images spanning over a century. To achieve this, we generate He i 10830 Å images from H α using a deep learning method, pix2pixHD. For model development, we use He i 10830 Å images from the National Solar Observatory (NSO)/Synoptic Optical Long-term Investigations of the Sun and H α images from NSO/Global Oscillation Network Group. Our model achieves a high correlation coefficient (CC) of 0.867 to reconstruct full-disk He i 10830 Å images. For solar structures like active regions, nonpolar, and polar crown filaments, we can achieve CCs of 0.903, 0.844, and 0.871, respectively. The model also shows reasonable performance on coronal holes with a CC of 0.536. Moreover, the model effectively generalized to data from multiple observatories, producing reliable results. In the early 2000s, when He i 10830 Å data was scarce, our model successfully reconstructed a scenario of an X-class flare eruption in the He i 10830 Å line covering the full observing period. This reconstruction included the formation of dark flare ribbons during the flare and postflare phases, showing a strong match with the postflare scenario observed by the Mauna Loa Solar Observatory/Chromospheric Helium Imaging Photometer.}, archive = {J_ApJ}, author = {Marco Marena and Qin Li and Haimin Wang and Bo Shen}, doi = {10.3847/1538-4357/adc7fc}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {99}, shortjournal = {The Astrophys. J.}, title = {Reconstructing he i 10830 Å images using hα images through deep learning}, volume = {984}, year = {2025}, }
• (2025). A discussion on the origin of the sub-PeV galactic gamma-ray emission. ApJ, 984(2), 98. (www)

  @article{ , abstract = {Galactic diffuse gamma-ray flux measured by the Tibet AS γ experiment and the total Galactic gamma-ray flux measured by the Large High Altitude Air Shower Observatory (LHAASO) are found to be consistent, within the statistical and systematic uncertainties, for the inner Galactic plane region in the sub-PeV energy range ( E > 10 14 eV). The result suggests that the sub-PeV Galactic gamma-ray flux is dominated by the diffuse emission. On the other hand, the LHAASO observations suggest that the sub-PeV gamma-ray sources presented in the first LHAASO catalog possibly give a significant contribution to the total sub-PeV Galactic gamma-ray emission (≈60%). However, the estimate must be regarded as a conservative upper limit in the sub-PeV energy range. In fact, current gamma-ray observations imply that many of the sub-PeV gamma-ray sources detected by LHAASO have a cutoff or significant softening in their energy spectra in the several tens of TeV energy range, and the resolved-source contribution to the total sub-PeV Galactic gamma-ray emission should be much lower than the above estimate. More sophisticated discussion about the origin of the sub-PeV Galactic gamma-ray emission requires detailed spectral studies of the individual gamma-ray sources and an accurate estimate of the contamination of the source fluxes from the diffuse emission.}, archive = {J_ApJ}, author = {S. Kato and R. Alves Batista and M. Anzorena and K. Awai and D. Chen and K. Fujita and R. Garcia and J. Huang and G. Imaizumi and T. Kawashima and K. Kawata and A. Mizuno and M. Ohnishi and C. Prévotat and T. Sako and T. K. Sako and F. Sugimoto and M. Takita and Y. Yokoe}, doi = {10.3847/1538-4357/adcb45}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {98}, shortjournal = {The Astrophys. J.}, title = {A discussion on the origin of the sub-PeV galactic gamma-ray emission}, volume = {984}, year = {2025}, }
• (2025). Investigating an erupting metric-decimetric radio depression and its physical origin. ApJ, 984(2), 97. (www)

  @article{ , abstract = {We present direct metric-decimetric radio imaging observations of a fascinating quiescent filament eruption on 2024 March 17 using data from the DAocheng Radio Telescope, with a combination of the Solar Dynamics Observatory and the Chinese H α Solar Explorer. At the radio band, even though the filament is difficult to identify in its early phase, it rapidly became distinct and formed a continuous loop-like dark structure during the eruption, i.e., so-called radio depression. Compared with the fragmentation of the erupting filament observed at the H α and EUV bands, the radio depression appeared more coherently. Based on synthetic radio images from a three-dimensional magnetohydrodynamics simulation of a flux-rope-filament eruption, it is suggested that the radio depression originates from the absorption of cold and dense materials within the erupting flux rope to the background emission. The absorption seems to be stronger than that at the H α and EUV bands, thus leading to their apparent discrepancies. Moreover, the radio depression is also found to occupy the lower part but not the whole body of the flux rope.}, archive = {J_ApJ}, author = {B. T. Wang and X. Cheng and J. Y. Yan and C. Xing and W. T. Fu and L. Wu and L. Deng and A. L. Lan and Y. Chen and C. Wang and M. D. Ding}, doi = {10.3847/1538-4357/adcb46}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {97}, shortjournal = {The Astrophys. J.}, title = {Investigating an erupting metric-decimetric radio depression and its physical origin}, volume = {984}, year = {2025}, }
• (2025). On the signature of black holes on the quenched stellar mass function. ApJ, 984(2), 96. (www)

  @article{ , abstract = {As star-forming galaxies approach or exceed a stellar mass of around 10 11 M ⊙ , they are increasingly likely to be quenched in a process generically called mass quenching. Central galaxies, which are quenched via mass rather than environmental quenching, therefore accumulate in a peak around this characteristic mass. While a number of processes may influence the shape of the quenched central stellar mass function, we find that its low-mass slope is strongly affected by the scatter in the mass of black holes at a given stellar mass, with higher scatters in the black hole population yielding shallower slopes. Higher scatters in the black hole mass spread out the stellar mass range over which quenching occurs, leading to shallower slopes. This trend holds across a variety of semianalytic models and cosmological hydrodynamic simulations. A comparison with observations provides indirect evidence for a large scatter in black hole mass \sigma ({\mathrm{log}}_{10}({M}_{{\rm{BH}}})| {M}_{* })\gtrsim 0.5 dex, and a joint constraint on active galactic nuclei feedback physics and the coevolution of galaxies and black holes.}, archive = {J_ApJ}, author = {Antonio J. Porras-Valverde and John C. Forbes}, doi = {10.3847/1538-4357/adcc2d}, journal = {The Astrophysical Journal}, month = {5}, number = {2}, pages = {96}, shortjournal = {The Astrophys. J.}, title = {On the signature of black holes on the quenched stellar mass function}, volume = {984}, year = {2025}, }
• (2025). The JWST/PASSAGE survey: Testing reionization histories with JWST’s first unbiased survey for lyα emitters at redshifts 7.5–9.5. ApJ, 984(1), 95. (www)

  @article{ , abstract = {Ly α emission is one of a few observable features of galaxies that can trace the neutral hydrogen content in the Universe during the Epoch of Reionization (EoR). To accomplish this, we need an efficient way to survey for Ly α emitters (LAEs) at redshifts beyond 7, requiring unbiased emission-line observations that are both sufficiently deep and wide to cover enough volume to detect them. Here we present results from PASSAGE—a pure-parallel JWST/NIRISS slitless spectroscopic survey to detect LAEs deep into the EoR, without the bias of photometric preselection. We identify four LAEs at 7.5 ≤ z ≤ 9.5 in four surveyed pointings and estimate the luminosity function (LF). We find that the LF does show a marked decrease compared to post-reionization measurements, but the change is a factor of ≲10, which is less than expected from theoretical calculations and simulations, as well as observational expectations from the pre-JWST literature. Modeling of the intergalactic medium and expected Ly α profiles implies that these galaxies reside in ionized bubbles of ⪆2 physical Mpc. We also report that in the four fields we detect {3, 1, 0, 0} LAEs, which could indicate strong field-to-field variation in the LAE distribution, consistent with a patchy H i distribution at z ∼ 8. We compare the recovered LAE number counts with expectations from simulations and discuss the potential implications for reionization and its morphology.}, archive = {J_ApJ}, author = {Axel Runnholm and Matthew J. Hayes and Vihang Mehta and Matthew A. Malkan and Claudia Scarlata and Kalina V. Nedkova and Marc Rafelski and Benedetta Vulcani and Mason Huberty and E. Christian Herenz and Anne Hutter and Sean Bruton and Ayan Acharyya and Hakim Atek and Ivano Baronchelli and Andrew J. Battisti and Maruša Bradač and Andrew J. Bunker and Y. Sophia Dai and Clea Hannahs and Farhanul Hasan and Keunho J. Kim and Nicha Leethochawalit and Yu-Heng Lin and Michael J. Rutkowski and Alberto Saldana-Lopez and Zahra Sattari and Xin Wang}, doi = {10.3847/1538-4357/adc008}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {95}, shortjournal = {The Astrophys. J.}, title = {The JWST/PASSAGE survey: Testing reionization histories with JWST’s first unbiased survey for lyα emitters at redshifts 7.5–9.5}, volume = {984}, year = {2025}, }
• (2025). Shining a light on the connections between galactic outflows seen in absorption and emission lines. ApJ, 984(1), 94. (www)

  @article{ , abstract = {Galactic outflows provide important feedback effects to regulate the evolution of host galaxies. Two primary diagnostics of outflows are broad and/or blueshifted emission and absorption lines. Even though well-established methods exist to analyze these outflow signatures, connections between them are rarely studied and largely unknown. In this paper, we conduct such a study in a sample of 33 low-redshift starburst galaxies. Their UV absorption lines are detected by the Hubble Space Telescope, and optical emission lines are observed by Keck or the Very Large Telescope. We find that the outflow properties derived from emission and absorption lines are tightly correlated. These include outflow maximum velocity, line width, and radial extent. On average, in the same galaxy, the maximum velocity and line width of outflows measured from emission lines reach only 60%–70% of those from the absorption lines. We also find outflow rates derived from emission lines are consistently lower than those from absorption lines by 0.2–0.5 dex. These findings can be explained by a radial decline in density and a corresponding increase in outflow velocity, combined with the fact that emission line luminosity scales with the square of the density while absorption line depth scales linearly. We test both spherical and biconical outflow models and find that the same radial outflow velocity and density distributions can explain the observed correlations. These results provide novel calibration between galactic outflow properties measured from the two diagnostics and underscore the need for high-fidelity UV and optical spectra to accurately assess galactic feedback effects in high- z galaxies.}, archive = {J_ApJ}, author = {Xinfeng Xu and Alaina Henry and Timothy Heckman and Cody Carr and Allison L. Strom and Tucker Jones and Danielle A. Berg and John Chisholm and Dawn Erb and Bethan L. James and Anne Jaskot and Crystal L. Martin and Matilde Mingozzi and Peter Senchyna and Namrata Roy and Claudia Scarlata and Daniel P. Stark}, doi = {10.3847/1538-4357/adc302}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {94}, shortjournal = {The Astrophys. J.}, title = {Shining a light on the connections between galactic outflows seen in absorption and emission lines}, volume = {984}, year = {2025}, }
• (2025). UNCOVERing the high-redshift AGN population among extreme UV line emitters. ApJ, 984(1), 93. (www)

  @article{ , abstract = {JWST has revealed diverse new populations of high-redshift ( z ∼ 4–11) active galactic nuclei (AGNs) and extreme star-forming galaxies that challenge current photoionization models. In this paper, we use rest-frame UV emission-line diagnostics to identify AGN candidates and other exceptional ionizing sources, complementing previous studies predominantly focused on broad-line AGNs. From a parent sample of 205 z spec > 3 UNCOVER galaxies with NIRSpec/PRISM follow-up, we identify 12 galaxies with C IV , He II , and/or C III ] emission. Three of these galaxies also exhibit clear N III ] and/or N IV ] lines. Leveraging the combined rest-optical and UV coverage of PRISM, we limit the emission-line model space using the sample's [O III ]/H β distribution, significantly decreasing the overlap between AGN and star formation models in the UV diagnostics. We then find that the five He II emitters are the strongest AGN candidates, with further support from two [Ne v ] detections and one X-ray detection from Chandra. Our Balmer line fits also reveal one new broad-line AGN at z = 6.87. We cannot robustly quantify the AGN fraction in this sample, but we note that close to 20% of M * > 2 × 10 9 M ⊙ parent sample galaxies are AGN candidates. The lower-mass line emitters, which are consistent with both AGN and star-forming photoionization models, have more compact sizes and higher specific star formation rates than the parent sample. Higher-resolution and deeper data on these UV line emitters should provide much stronger constraints on the obscured AGN fraction at z > 3.}, archive = {J_ApJ}, author = {Helena Treiber and Jenny E. Greene and John R. Weaver and Tim B. Miller and Lukas J. Furtak and David J. Setton and Bingjie Wang and Anna de Graaff and Rachel Bezanson and Gabriel Brammer and Sam E. Cutler and Pratika Dayal and Robert Feldmann and Seiji Fujimoto and Andy D. Goulding and Vasily Kokorev and Ivo Labbe and Joel Leja and Danilo Marchesini and Themiya Nanayakkara and Erica Nelson and Richard Pan and Sedona H. Price and Jared Siegel and Katherine A. Suess and Katherine E. Whitaker}, doi = {10.3847/1538-4357/adc38f}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {93}, shortjournal = {The Astrophys. J.}, title = {UNCOVERing the high-redshift AGN population among extreme UV line emitters}, volume = {984}, year = {2025}, }
• (2025). Measurement of methane line broadening in hot Hydrogen/Helium atmospheres at λ = 1.60–1.63 μm for substellar object spectroscopy. ApJ, 984(1), 92. (www)

  @article{ , abstract = {Recent high-dispersion spectroscopy from ground-based telescopes and high-precision spectroscopy from space observatories have enabled atmospheric observations of substellar objects, such as brown dwarfs and hot gaseous exoplanets, with sufficient precision to make ambient gas differences in molecular line broadening a significant factor. In this paper, we experimentally measured the pressure broadening of methane in a high-temperature hydrogen–helium background atmosphere in the H band, which had not been previously measured. The experiment used glass cells, inserted in a tube furnace, filled with methane in a hydrogen–helium background atmosphere or pure methane gas. Spectra were obtained at four temperatures ranging from room temperature to 1000 K, in the wavelength range 1.60–1.63 μ m, using a tunable laser, yielding eight high-resolution spectra in total. A full Bayesian analysis was performed on the obtained spectra, using the differentiable spectral model ExoJAX and the Hamiltonian Monte Carlo for inferring a large number of parameters, allowing us to infer the H 2 /He pressure broadening for 22 transitions mainly in the R branch of the 2 ν 3 band. As a result, we found a temperature exponent of approximately 0.27 and a reference width at 296 K of around 0.040 for J lower = 13–20. This temperature dependency is much milder than that provided by the molecular database ExoMol, yielding a line width approximately 5%–45% smaller than ExoMol at 296 K, but similar at 1000 K. Our results suggest the need for further accumulation of experimental data for spectral analysis of substellar objects with hydrogen–helium atmospheres.}, archive = {J_ApJ}, author = {Ko Hosokawa and Takayuki Kotani and Hajime Kawahara and Yui Kawashima and Kento Masuda and Aoi Takahashi and Kazuo Yoshioka}, doi = {10.3847/1538-4357/adc455}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {92}, shortjournal = {The Astrophys. J.}, title = {Measurement of methane line broadening in hot Hydrogen/Helium atmospheres at λ = 1.60–1.63 μm for substellar object spectroscopy}, volume = {984}, year = {2025}, }
• (2025). Irradiated atmospheres. II. interplay between scattering and vertical-mixing-induced energy transport. ApJ, 984(1), 91. (www)

  @article{ , abstract = {Scattering is crucial for the atmospheric thermal profiles. The energy transport by vertical mixing plays an essential role in the greenhouse or anti-greenhouse effect. This work explores the interaction between scattering and vertical mixing, specifically whether these processes enhance or mitigate each other's effects on atmospheric temperature. The interaction between mixing flux and scattering is nonlinear. Our calculations indicate that thermal scattering intensifies the greenhouse effects caused by vertical mixing in the middle atmosphere but reduces them in the lower layers. In the middle atmosphere, increased vertical mixing enhances the warming effect of thermal scattering while diminishing the cooling effect of visible scattering. In the lower atmosphere, it enhances the anti-greenhouse effect linked to visible scattering and diminishes the greenhouse effect produced by thermal scattering. The combined influence of thermal scattering and vertical mixing on the lower atmosphere's greenhouse effect is weaker than their separate impacts, akin to 1 + 1 < 2. It is also interesting to note that the joint effect may also influence chemistry and cloud formation, altering the thermal structure.}, archive = {J_ApJ}, author = {Zhen-Tai Zhang and Wei Zhong and Xianyu Tan and Bo Ma and Ruyi Wei and Cong Yu}, doi = {10.3847/1538-4357/adc56b}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {91}, shortjournal = {The Astrophys. J.}, title = {Irradiated atmospheres. II. interplay between scattering and vertical-mixing-induced energy transport}, volume = {984}, year = {2025}, }
• (2025). The effects of kinematic magnetohydrodynamics on the atmospheric circulation of eccentric hot jupiters. ApJ, 984(1), 90. (www)

  @article{ , abstract = {Hot Jupiters are typically considered to be tidally locked due to their short orbital periods. The extreme irradiation can result in atmospheric species becoming thermally ionized on the dayside, which then interact with the planet's magnetic field by resisting flow across magnetic field lines, shaping the atmospheric structure. However, an eccentric orbit results in temporally dependent irradiation and a nonpermanent dayside, as the planet–star distance can change drastically during its orbit. In this paper, we present 3D atmospheric models of TOI-150b, an eccentric ( e = 0.26), Jupiter-mass (∼1.75 M Jup ) planet whose equilibrium temperature varies from 1300 to 1700 K. We conduct simulations for magnetic field strengths ranging from 0 to 30 Gauss using the kinematic magnetohydrodynamics (MHD) approach. When compared with simulations of the planet assuming a circular orbit, we find that the eccentric orbit results in a strengthened and narrowed equatorial jet, westward winds at midlatitudes, and a phase-dependent thermal inversion. The strength and magnitude of these effects scale with the chosen global magnetic field strength. We also generate high-resolution ( R = 100,000) emission spectra to study net Doppler shifts and find interorbit spectroscopic variability at moderate magnetic field strengths, as well as decreased Doppler broadening as magnetic field strengths increase. This work represents the first time that the kinematic MHD approach has been applied to an eccentric hot Jupiter and highlights the importance of a locally calculated, temperature-dependent magnetic drag prescription for predicting atmospheric structure and resulting spectra.}, archive = {J_ApJ}, author = {Hayley Beltz and Willow Houck and L. C. Mayorga and Thaddeus D. Komacek and Joseph R. Livesey and Juliette Becker}, doi = {10.3847/1538-4357/adc56c}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {90}, shortjournal = {The Astrophys. J.}, title = {The effects of kinematic magnetohydrodynamics on the atmospheric circulation of eccentric hot jupiters}, volume = {984}, year = {2025}, }
• (2025). Period–Luminosity relations for double-mode δ sct stars. ApJ, 984(1), 89. (www)

  @article{ , abstract = {Previous studies of the period–luminosity relations (PLRs) of Delta Scuti ( δ Sct) stars have focused on those with a single pulsation mode. However, for δ Sct stars with many different pulsation modes, classifying a single mode is difficult. In this study, an all-sky data set is constructed using double-mode δ Sct stars from the Zwicky Transient Facility and Optical Gravitational Lensing Experiment and is used to determine fundamental (F)-mode and first-overtone (1O)-mode PLRs for eight single bands and six Wesenheit bands. In the W 1 band, the PLR dispersion is about 0.171 mag, and the total zero-point error is 1%. Our results show that to accurately classify the 1O modes of δ Sct stars requires authentication based on multiple modes. Classification based on amplitude alone leads to impure 1O-mode δ Sct stars and significant deviations in the PLRs. We compare the PLRs of the different sequences in the Petersen diagram and find that they are consistent after a strict criterion filtering, suggesting that their evolutionary state is similar. In addition, we find a weak period–metallicity relation for double-mode δ Sct stars, unlike double-mode RR Lyrae stars. As distance tracers, large-amplitude F-mode δ Sct and double-mode δ Sct stars are the most suitable of the δ Sct family.}, archive = {J_ApJ}, author = {Qi Jia and Xiaodian Chen and Shu Wang and Licai Deng and Jianxing Zhang and Qingquan Jiang}, doi = {10.3847/1538-4357/adc685}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {89}, shortjournal = {The Astrophys. J.}, title = {Period–Luminosity relations for double-mode δ sct stars}, volume = {984}, year = {2025}, }
• (2025). Helicity effect on turbulent passive and active scalar diffusivities. ApJ, 984(1), 88. (www)

  @article{ , abstract = {Turbulent flows are known to produce enhanced effective magnetic and passive scalar diffusivities, which can fairly accurately be determined with numerical methods. It is now known that, if the flow is also helical, the effective magnetic diffusivity is reduced relative to the nonhelical value. Neither the usual second-order correlation approximation nor the various τ approaches have been able to capture this. Here we show that the helicity effect on the turbulent passive scalar diffusivity works in the opposite sense and leads to an enhancement. We have also demonstrated that the correlation time of the turbulent velocity field increases with the kinetic helicity. This is a key point in the theoretical interpretation of the obtained numerical results. Simulations in which helicity is being produced self-consistently by stratified rotating turbulence resulted in a turbulent passive scalar diffusivity that was found to be decreasing with increasing rotation rate.}, archive = {J_ApJ}, author = {Axel Brandenburg and Petri J. Käpylä and Igor Rogachevskii and Nobumitsu Yokoi}, doi = {10.3847/1538-4357/adc691}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {88}, shortjournal = {The Astrophys. J.}, title = {Helicity effect on turbulent passive and active scalar diffusivities}, volume = {984}, year = {2025}, }
• (2025). The struggles of developing an operational machine learning model for flare forecasting: Recasting the problem as a regression onto X-ray flux. ApJ, 984(1), 87. (www)

  @article{ , abstract = {Complex machine learning (ML) models do not seem to have improved solar flare forecasting. Despite many efforts to apply deep neural network architectures, it is unclear whether these models truly offer improvements compared to classical statistical and ML techniques because consistent benchmark test sets are underused and few papers offer comparisons to baseline models. In particular, predicting the onset and decline of flaring activity is an unsolved challenge. One possibility for the lack of improvement in performance is that the flare forecasting problem has been cast as one of binary classification, which forces models to try to distinguish between flares below and above an arbitrary intensity threshold. Here, we define a fully regression-based forecasting task and present results for full-disk forecasts of the maximum X-ray flux within a given forecast window using models trained on historical magnetogram data. We compare various ML architectures and show that a hybrid convolutional neural network only offers comparable performance to a simple random forest model. This demonstrates the continued value of a small set of predictive scalar features in flare forecasting and the importance of comparing to a baseline. By showing how performance varies depending on the choice of test set, we also emphasize the need to simulate operational conditions when evaluating forecasting models. We do not claim to have developed a more skillful flare forecasting model in this work; rather, we seek to highlight key challenges and best practices within the context of investigating a regression task for flare prediction.}, archive = {J_ApJ}, author = {Kiera van der Sande and Andrés Muñoz-Jaramillo}, doi = {10.3847/1538-4357/ad8de5}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {87}, shortjournal = {The Astrophys. J.}, title = {The struggles of developing an operational machine learning model for flare forecasting: Recasting the problem as a regression onto X-ray flux}, volume = {984}, year = {2025}, }
• (2025). Theoretical foundation of black hole image reconstruction using PRIMO. ApJ, 984(1), 86. (www)

  @article{ , abstract = {A new image-reconstruction algorithm, Principal-component Interferometric Modeling ( PRIMO ), applied to the interferometric data of the M87 black hole collected with the Event Horizon Telescope (EHT), resulted in an image that reached the native resolution of the telescope array. PRIMO is based on learning a compact set of image building blocks obtained from a large library of high-fidelity, physics-based simulations of black hole images. It uses these building blocks to fill the sparse Fourier coverage of the data that results from the small number of telescopes in the array. In this paper, we show that this approach is readily justified. Since the angular extent of the image of the black hole and of its inner accretion flow is finite, the Fourier space domain is heavily smoothed, with a correlation scale that is at most comparable to the sizes of the data gaps in the coverage of Fourier space with the EHT. Consequently, PRIMO or other machine learning algorithms can faithfully reconstruct the images without the need to generate information that is unconstrained by the data within the resolution of the array. We also address the completeness of the eigenimages and the compactness of the resulting representation. We show that PRIMO provides a compact set of eigenimages that have sufficient complexity to recreate a broad set of images well beyond those in the training set.}, archive = {J_ApJ}, author = {Dimitrios Psaltis and Feryal Özel and Lia Medeiros and Tod R. Lauer}, doi = {10.3847/1538-4357/ada60f}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {86}, shortjournal = {The Astrophys. J.}, title = {Theoretical foundation of black hole image reconstruction using PRIMO}, volume = {984}, year = {2025}, }
• (2025). CO observations of the SMC-n66 h ii region with ALMA: Properties of clumps along filamentary molecular clouds and possible expansion motion. ApJ, 984(1), 85. (www)

  @article{ , abstract = {The star-forming region N66, as a host of the majority of OB stars in the Small Magellanic Cloud, provides a unique opportunity to enhance our understanding of the triggers of high-mass star formation. We investigate the properties of the molecular cloud in N66 using the 12 CO(1–0) data obtained with the Atacama Large Millimeter/submillimeter Array. A cloud decomposition analysis identified 165 independent cloud structures and substructures. The size–linewidth scaling relation for the entire region exhibits an index of 0.49, indicating that the region is in a state of virial equilibrium. In contrast, a detailed analysis of the central N66 region revealed a size–line width scaling relation with an index of 0.75, suggesting that distinct factors are influencing the dynamics of this central area. Averaging the spectra in the central N66 region revealed three distinct velocity peaks at 145, 152, and 160 km s −1 , indicating that some kinds of interactions are occurring within the cloud. The analysis of the position–velocity diagrams in the central region revealed a ring-like structure, indicating the presence of an expanding bubble. The bubble exhibits supersonic characteristics, with an expansion velocity of {v}_{{\rm{\exp }}}\approx 11 km s −1 , and an overall systemic velocity of v sys ≈ 151 km s −1 . The radius is estimated to be in the range of r ≈ [9.8−12.9] ± 0.5 pc and is approximately 1.2 Myr old.}, archive = {J_ApJ}, author = {Batool Ilyasi and Naslim Neelamkodan and Kazuki Tokuda and Susmita Barman and Marta Sewiło and Hidetoshi Sano and Toshikazu Onishi}, doi = {10.3847/1538-4357/adbf16}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {85}, shortjournal = {The Astrophys. J.}, title = {CO observations of the SMC-n66 h ii region with ALMA: Properties of clumps along filamentary molecular clouds and possible expansion motion}, volume = {984}, year = {2025}, }
• (2025). Analysis of X-ray surface brightness radial profiles in several relatively symmetric young supernova remnants. ApJ, 984(1), 84. (www)

  @article{ , abstract = {Based on observations from XMM-Newton, we analyze the surface brightness radial profiles of several young supernova remnants (SNRs) with relatively symmetric structures. The surface brightness data are obtained from the MOS1, MOS2, and PN instruments. We fit these profiles using a phenomenological model combining Gaussian and β models. Our results reveal a significant difference between SNRs with bright shell edges and those with faint shell edges. SNRs with bright shell edges exhibit a surface brightness peak within a certain range. In contrast, SNRs with faint shell edges show a gradual decrease in brightness, indicating differences in the physical mechanisms driving their evolution. Subsequently, we use the Gaussian and β models to fit these profiles. The results effectively reflect their evolutionary trends and brightness distribution, indicating that the internal part of the profiles is generally expressed by the Gaussian models, while the external part is characterized by the β model. Notably, the β -values in our model closely approximate the expansion parameters of the SNRs. This intriguing similarity suggests that detailed analyses of surface brightness radial profiles may provide valuable insights into the expansion dynamics of SNRs.}, archive = {J_ApJ}, author = {Jin Cao and Yunyong Tang and Keli Peng and Nan Ding and Jinjie Yu}, doi = {10.3847/1538-4357/adbf20}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {84}, shortjournal = {The Astrophys. J.}, title = {Analysis of X-ray surface brightness radial profiles in several relatively symmetric young supernova remnants}, volume = {984}, year = {2025}, }
• (2025). Vortex avalanches and collective motion in neutron stars. ApJ, 984(1), 83. (www)

  @article{ , abstract = {We simulate the dynamics of about 600 quantum vortices in a spinning-down cylindrical container using a Gross–Pitaevskii model. For the first time, we find convincing spatial-temporal evidence of avalanching behavior resulting from vortex depinning and collective motion. During a typical avalanche, about 10–20 vortices exit the container in a short period, producing a glitch in the superfluid angular momentum and a localized void in the vorticity. After the glitch, vortices continue to depin and circulate around the vorticity void in a similar manner to that seen in previous point-vortex simulations. We present evidence of collective vortex motion throughout this avalanche process. We also show that the effective Magnus force can be used to predict when and where avalanches will occur. Finally, we comment on the challenge of extrapolating these results to conditions in real neutron stars, which contain many orders of magnitude more vortices.}, archive = {J_ApJ}, author = {I-Kang Liu and Andrew W. Baggaley and Carlo F. Barenghi and Toby S. Wood}, doi = {10.3847/1538-4357/adc383}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {83}, shortjournal = {The Astrophys. J.}, title = {Vortex avalanches and collective motion in neutron stars}, volume = {984}, year = {2025}, }
• (2025). Closeby habitable exoplanet survey (CHES). III. retrieval of planetary masses in binaries using the N-body model with radial velocity and astrometry synergy. ApJ, 984(1), 82. (www)

  @article{ , abstract = {Given that secular perturbations in a binary system not only excite high orbital eccentricities but also alter the planetary orbital inclination, the classical Keplerian orbital model is no longer applicable for orbital retrieval. The combination of a dynamical model and observational data is essential for characterizing the configuration and planetary mass in close binaries. We calculate the theoretical radial velocity (RV) signal in the N -body framework and observe a drift in the RV semiamplitude, which leads to a reduction in the m sin i detection threshold by 20 M ⊕ , with ∼100% detection probability in the m 1 sin i 1 – a 1 parameter space. High-precision RV data with an accuracy of 1 m s −1 can detect such dynamical effects. For four close-in binaries—GJ 86, GJ 3021, HD 196885, and HD 41004—the deviation between the minimum mass derived from the Keplerian and N -body models is found to be >0.2 M Jup . High-precision astrometric data are also necessary to resolve the 3D orbits and true masses of exoplanets. We generate astrometric simulation data with accuracies corresponding to Gaia (57.8 μ as) and the Closeby Habitable Exoplanet Survey (CHES; 1 μ as), respectively. Joint orbit fitting is performed for RV+Gaia and RV+CHES synergy methods. Compared with the fitting results from the astrometry-only model, the synergy models more effectively constrain the range of orbital inclinations. Using simulation data, we derive precise uncertainties for the true planetary mass, which are critical for determining the evolution of planets around binary stars and multiplanet systems.}, archive = {J_ApJ}, author = {Xiumin Huang and Jianghui Ji and Chunhui Bao and Dongjie Tan and Su Wang and Yao Dong and Guo Chen}, doi = {10.3847/1538-4357/adc444}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {82}, shortjournal = {The Astrophys. J.}, title = {Closeby habitable exoplanet survey (CHES). III. retrieval of planetary masses in binaries using the N-body model with radial velocity and astrometry synergy}, volume = {984}, year = {2025}, }
• (2025). GRB 170519A: Thermal radiation in an X-ray flare and decaying magnetic fields for the early-time afterglow. ApJ, 984(1), 81. (www)

  @article{ , abstract = {GRB 170519A was discovered by the Swift Burst Alert Telescope (BAT) and then observed by the Swift X-Ray Telescope, Swift UltraViolet and Optical Telescope, and ground-based telescopes. We report Lick Katzman Automatic Imaging Telescope observations of GRB 170519A and make temporal analysis and spectral joint fits of its multiwavelength light curves. The observations present a relatively complete afterglow structure, including two X-ray flares (Flares I and II), optical onset (Slice 1), normal decay (Slices 2 and 3), and a possible jet break. The spectrum of the bright X-ray flare (Flare II) indicates that a thermal component exists at t = 190–240 s. The blackbody (BB) emits in the photospheric radius R ph ∼ 10 11 cm, and its temperature ( kT ) decreases with time from 1.08 to 0.37 keV, while its Lorentz factor of BB (Γ BB ) decreases with time from 67.71 to 46.70. The luminosity of the BB ( L BB ), kT , and Γ BB follows the relations L BB ∝ kT 2.49±0.03 and {{\rm{\Gamma }}}_{{\rm{BB}}}\propto {L}_{{\rm{BB}}}^{0.27} . In the optical light curves, there is an onset bump in the early-time afterglow, rising with an index α O,1 ≈ −0.43 and peaking ∼1174.9 s since the BAT trigger. The bump then decays with α O,2 ≈ 0.88 in the normal decay phase, and the X-ray flux decays with a similar index of α X ,1 ≈ 0.95. There is no obvious spectral evolution in the normal decay phases, with photon index \hat{{\rm{\Gamma }}}=1.86 and 1.92 in Slices 2 and 3, respectively. We find that the multiwavelength light curves of the GRB 170519A afterglow can be well fitted by an external shock with time-dependent B . In the early afterglow, the value of B decays rapidly from 4.29 × 10 −2 to 8.23 × 10 −3 .}, archive = {J_ApJ}, author = {Zi-Min Zhou and Liang-Jun Chen and Rui-Quan Li and Xiang-Gao Wang and Xing-Ling, Li and En-Wei Liang and WeiKang Zheng and Alexei V. Filippenko}, doi = {10.3847/1538-4357/adc45c}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {81}, shortjournal = {The Astrophys. J.}, title = {GRB 170519A: Thermal radiation in an X-ray flare and decaying magnetic fields for the early-time afterglow}, volume = {984}, year = {2025}, }
• (2025). Using two-frequency dust spectral matching to separate galactic synchrotron and Free–Free temperature foregrounds from the cosmic microwave background. ApJ, 984(1), 80. (www)

  @article{ , abstract = {We introduce a method for removing cosmic microwave background (CMB) and anomalous microwave emission (AME, or spinning dust) intensity signals at high to intermediate Galactic latitudes in temperature sky maps at frequencies roughly between 5 and 40 GHz. The method relies on the assumption of a spatially uniform combined dust (AME and thermal) rms spectral energy distribution for these regions but is otherwise model independent. A difference map is produced from input maps at two different frequencies in thermodynamic temperature: the two frequencies are chosen such that the rms AME signal in the lower-frequency (∼5−40 GHz) map is equivalent to the thermal dust emission rms in the higher-frequency (∼95−230 GHz) map. Given the high spatial correlation between AME and thermal dust, the resulting difference map is dominated by synchrotron and free–free foreground components and can thus provide useful insight into the morphology and possible spectral variations of these components at high latitudes. We show examples of these difference maps obtained with currently available WMAP and Planck data and demonstrate the efficacy of CMB and dust mitigation using this method. We also use these maps, in conjunction with Haslam 408 MHz and Wisconsin H-Alpha Mapper H α observations, to form an estimate of the diffuse synchrotron spectral index in brightness temperature on degree scales. The hybrid analysis approach we describe is advantageous in situations where frequency coverage is insufficient to break spectral degeneracies between AME and synchrotron.}, archive = {J_ApJ}, author = {J. L. Weiland and Charles L. Bennett and Graeme E. Addison and Mark Halpern and Gary Hinshaw}, doi = {10.3847/1538-4357/adc4db}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {80}, shortjournal = {The Astrophys. J.}, title = {Using two-frequency dust spectral matching to separate galactic synchrotron and Free–Free temperature foregrounds from the cosmic microwave background}, volume = {984}, year = {2025}, }
• (2025). Chandra discovery of a candidate hyperluminous X-ray source in MCG+11-11-032. ApJ, 984(1), 79. (www)

  @article{ , abstract = {We present a multiwavelength analysis of MCG+11-11-032, a nearby active galactic nucleus (AGN), with a unique classification as being both a binary and a dual AGN candidate. With new Chandra observations, we aim to resolve any dual AGN system via imaging data and search for signs of a binary AGN via analysis of the X-ray spectrum. Analyzing the Chandra spectrum, we find no evidence of the previously suggested double-peaked Fe K α lines; the spectrum is instead best fit by an absorbed power law with a single Fe K α line, as well as an additional line centered at ≈7.5 keV. The Chandra observation reveals faint, soft, and extended X-ray emission, possibly linked to low-level nuclear outflows. Further analysis shows evidence for a compact hard source—MCG+11-11-032 X2—located 3 \mathop{.}\limits^{\unicode{x02033}} 3 from the primary AGN. Modeling MCG+11-11-032 X2 as a compact source, we find that it is relatively luminous ( {L}_{\,\rm{2\unicode{x02013}10 keV}\,}=1.{5}_{-0.5}^{+0.9}\times 1{0}^{41} erg s −1 ), and the location is coincident with a compact and off-nuclear source resolved in Hubble Space Telescope infrared (F105W) and optical (F621M, F547M) bands. Pairing our X-ray results with a 144 MHz radio detection at the host galaxy location, we observe X-ray and radio properties similar to those of ESO 243-49 HLX-1, suggesting that MCG+11-11-032 X2 may be a hyperluminous X-ray source. This detection with Chandra highlights the importance of a high-resolution X-ray imager as well as how previous binary AGN candidates detected with large-aperture instruments can benefit from high-resolution follow-up. Future spatially resolved optical spectra, and deeper X-ray observations, can better constrain the origin of MCG+11-11-032 X2.}, archive = {J_ApJ}, author = {Adi Foord and Francesca Civano and Julia M. Comerford and Martin Elvis and Giuseppina Fabbiano and Tingting Liu and Elisabeta Lusso and Stefano Marchesi and Mar Mezcua and Francisco Muller-Sanchez and Rebecca Nevin and Kristina Nyland}, doi = {10.3847/1538-4357/adc4e8}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {79}, shortjournal = {The Astrophys. J.}, title = {Chandra discovery of a candidate hyperluminous X-ray source in MCG+11-11-032}, volume = {984}, year = {2025}, }
• (2025). Magnetic helicity fluxes in dynamos from rotating inhomogeneous turbulence. ApJ, 984(1), 78. (www)

  @article{ , abstract = {We analyze direct numerical simulations of large-scale dynamos in inhomogeneous nonhelically driven rotating turbulence with and without shear. The forcing is modulated so that the turbulent intensity peaks in the middle of the computational domain and drops to nearly zero at the two ends above and below the midplane. A large-scale dynamo is driven by an α effect of opposite signs in the two hemispheres. In the presence of shear, the hemispheric magnetic helicity flux from small-scale fields becomes important and can even overcompensate for the magnetic helicity transferred by the α effect between large and small scales. This effect has not previously been observed in nonshearing simulations. Our numerical simulations show that the hemispheric magnetic helicity fluxes are nearly independent of the magnetic Reynolds number, but those between large and small scales, and the consequent dynamo effect, are still found to decrease with increasing Reynolds number—just like in nonshearing dynamos. However, in contrast to nonshearing dynamos, where the generated mean magnetic field declines with increasing magnetic Reynolds number, it is now found to remain independent of it. This suggests that catastrophic dynamo quenching is alleviated by the shear-induced hemispheric small-scale magnetic helicity fluxes that can even overcompensate the fluxes between large and small scales and thereby cause resistive contributions.}, archive = {J_ApJ}, author = {Axel Brandenburg and Ethan T. Vishniac}, doi = {10.3847/1538-4357/adc561}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {78}, shortjournal = {The Astrophys. J.}, title = {Magnetic helicity fluxes in dynamos from rotating inhomogeneous turbulence}, volume = {984}, year = {2025}, }
• (2025). A unified model of kilonovae and gamma-ray bursts in binary mergers establishes neutron stars as the central engines of short GRBs. ApJ, 984(1), 77. (www)

  @article{ , abstract = {We expand the theoretical framework by O. Gottlieb et al., which connects binary merger populations with long and short binary gamma-ray bursts (lbGRBs and sbGRBs, respectively), incorporating kilonovae (KNe) as a key diagnostic tool. We show that lbGRBs, powered by massive accretion disks around black holes (BHs), should be accompanied by bright, red KNe. In contrast, sbGRBs—if also powered by BHs—would produce fainter, red KNe, potentially biasing against their detection. However, magnetized hypermassive neutron star (HMNS) remnants that precede BH formation can produce jets with power ( P NS ≈ 10 51 erg s −1 ) and Lorentz factor (Γ > 10) likely compatible with sbGRB observations, and would result in distinctly bluer KNe, offering a pathway to identifying the sbGRB central engine. Recent modeling by J. C. Rastinejad et al. found luminous red KNe consistently accompany lbGRBs, supporting their origin in BH-massive disk systems, likely following a short-lived HMNS phase. The preferential association of sbGRBs with comparably luminous KNe argues against the BH engine hypothesis for sbGRBs, while the bluer hue of these KNe provides additional support for an HMNS-driven mechanism. Within this framework, BH–NS mergers likely contribute exclusively to the lbGRB population with red KNe. Our findings suggest that GW170817 may, in fact, have been an lbGRB to on-axis observers. Finally, we discuss major challenges faced by alternative lbGRB progenitor models, such as white dwarf–NS or white dwarf–BH mergers and accretion-induced collapse forming magnetars, which fail to align with observed GRB timescales, energies, and KN properties.}, archive = {J_ApJ}, author = {Ore Gottlieb and Brian D. Metzger and Francois Foucart and Enrico Ramirez-Ruiz}, doi = {10.3847/1538-4357/adc577}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {77}, shortjournal = {The Astrophys. J.}, title = {A unified model of kilonovae and gamma-ray bursts in binary mergers establishes neutron stars as the central engines of short GRBs}, volume = {984}, year = {2025}, }
• (2025). Physical properties and h i-to-h2 transition across taurus linear edge. ApJ, 984(1), 76. (www)

  @article{ , abstract = {Studying the atomic-to-molecular transition is essential for understanding the evolution of the interstellar medium. The linear edge of the Taurus molecular cloud, clearly identified in the 13 CO(1–0) intensity map, serves as an ideal site for investigating this transition. Utilizing the Arizona Radio Observatory Submillimeter Telescope, we obtained mapping observations of CO(2–1), 13 CO(2–1), and CO(3–2) across this linear edge. The intensity ratio between CO(2–1) and 13 CO(2–1) indicates a lower limit of the 12 C / 13 C ratio of 54 ± 17. Based on multitransition observations of CO and 13 CO, we performed a Markov Chain Monte Carlo fit of the physical properties across this edge using non–local thermodynamic equilibrium analysis with the RADEX code, based on the large velocity gradient assumption. The number density profile exhibits a pronounced jump coinciding with the H 2 infrared emission peak. The cold H i gas within the molecular cloud, manifested as H i narrow self-absorption features, is detected along the cloud edge. Our quantitative comparison with numerical simulations provides tentative evidence that shocks induced by colliding gas flows may contribute to the atomic-to-molecular phase transition observed along the linear edge.}, archive = {J_ApJ}, author = {Ningyu Tang and Feihang Miao and Gan Luo and Di Li and Junzhi Wang and Fujun Du and Donghong Wu and Shu Liu}, doi = {10.3847/1538-4357/adc686}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {76}, shortjournal = {The Astrophys. J.}, title = {Physical properties and h i-to-h2 transition across taurus linear edge}, volume = {984}, year = {2025}, }
• (2025). Dynamics of star cluster formation: The effects of ongoing star formation and stellar feedback. ApJ, 984(1), 75. (www)

  @article{ , abstract = {We perform a high-resolution zoomed-in simulation of star cluster assembly including the merger of two subclusters with initial conditions taken from previous large-scale giant molecular cloud (GMC) simulations. We couple hydrodynamics to N -body dynamics to simulate the individual stars themselves, and the gas-rich environment in which they evolve. We include prescriptions for star formation and stellar feedback and compare them directly to previous simulations of the same region without these prescriptions to determine their role in shaping the dynamics inherited from the cluster assembly process. The stellar mass of the cluster grows through star formation within the cluster and accretion of new stars and star-forming gas from a nearby filament. This growth results in an enhancement in the cluster's rotation and anisotropic expansion compared to simulations without star formation. We also analyze the internal kinematics of the cluster once it has lost most of its gas and find that the rotational velocity and the velocity anisotropy profiles are qualitatively similar to those expected of clusters that have undergone violent relaxation. Additionally, rotation and anisotropic expansion are still present by the time of gas removal. This implies that evolution within the GMC was unable to completely erase the kinematics inherited by the merger.}, archive = {J_ApJ}, author = {Jeremy Karam and Michiko S. Fujii and Alison Sills}, doi = {10.3847/1538-4357/adc719}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {75}, shortjournal = {The Astrophys. J.}, title = {Dynamics of star cluster formation: The effects of ongoing star formation and stellar feedback}, volume = {984}, year = {2025}, }
• (2025). The diversity of cold worlds: A blended-light binary straddling the T/Y transition in brown dwarfs. ApJ, 984(1), 74. (www)

  @article{ , abstract = {We present the first brown dwarf spectral binary characterized with JWST: WISE J014656.66+423410.0, the coldest blended-light brown dwarf binary straddling the T/Y transition. We obtained a moderate resolution ( R ∼ 2700) G395H spectrum of this unresolved binary with JWST/NIRSpec and we fit it to late T and Y dwarf spectra from JWST/NIRSpec, and model spectra of comparable temperatures, both as individual spectra and pairs mimicking an unresolved binary system. We find that this tightly separated binary is likely composed of two unequal-brightness sources with a magnitude difference of 0.50 ± 0.08 mag in IRAC [4.5] and a secondary 1.01 ± 0.13 mag redder than the primary in [3.6]–[4.5]. Despite the large color difference between the best-fit primary and secondary, their temperature difference is only 92 ± 23 K, a feature reminiscing of the L/T transition. Carbon disequilibrium chemistry strongly shapes the mid-infrared spectra of these sources, as a complex function of the metallicity and surface gravity. While a larger library of JWST/NIRSpec spectra is needed to conclusively examine the peculiarities of blended-light sources, this spectral binary is a crucial pathfinder to both understand the spectral features of planetary-mass atmospheres and detect binarity in unresolved, moderate-resolution spectra of the coldest brown dwarfs.}, archive = {J_ApJ}, author = {Daniella C. Bardalez Gagliuffi and Jacqueline K. Faherty and Genaro Suárez and Sherelyn Alejandro Merchan and Brianna Lacy and Ben Burningham and Klara Matuszewska and Rocio Kiman and Johanna M. Vos and Austin Rothermich and Jonathan Gagné and Caroline Morley and Melanie J. Rowland and Dan Caselden and Aaron Meisner and Adam C. Schneider and Marc J. Kuchner and Charles A. Beichman and Peter R. Eisenhardt and Christopher R. Gelino and Ehsan Gharib-Nezhad and Eileen C. Gonzales and Federico Marocco and Niall Whiteford and J. Davy Kirkpatrick}, doi = {10.3847/1538-4357/adb61e}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {74}, shortjournal = {The Astrophys. J.}, title = {The diversity of cold worlds: A blended-light binary straddling the T/Y transition in brown dwarfs}, volume = {984}, year = {2025}, }
• (2025). Central velocity dispersion as the primary driver of abundance patterns in quenched galaxies. ApJ, 984(1), 73. (www)

  @article{ , abstract = {The element abundances of galaxies provide crucial insights into their formation and evolution. Using high-resolution integral field unit data from the Mapping Nearby Galaxies at Apache Point Observatory survey, we analyze the central spectra (0–0.5 R e ) of 1185 quenched galaxies ( z = 0.012−0.15) to study their element abundances and stellar populations. We employ the full-spectrum fitting code alf to derive stellar ages and element abundances from synthetic spectra and empirical libraries. Our key findings are: (1) the central velocity dispersion ( σ * ) is the most effective parameter correlating with the (relative) element abundances, especially [Na/Fe], [Mg/Fe], [C/Fe], and [N/Fe], outperforming M * and M * / R e ; (2) when binned by σ * , the relative abundances of Na, Mg, C, and N remain stable across different formation times ( T form ), suggesting these elements are primarily influenced by the burstiness of star formation (traced by σ * ) rather than prolonged evolutionary processes; and (3) Fe and Ca show little variation with σ * , indicating weaker sensitivity to σ * -driven processes. However, T form has a global influence on all elements, contributing to their overall chemical evolution, although this is secondary to σ * for most elements. These results support the primary role of σ * in shaping the abundance patterns, likely stemming from the connection with central massive black holes and possibly also that with dark matter halos, which influences the burstiness of star formation histories.}, archive = {J_ApJ}, author = {Haixin Li and Enci Wang and Cheqiu Lyu and Yangyao Chen and Huiyuan Wang and Zeyu Chen and Haoran Yu and Cheng Jia and Chengyu Ma}, doi = {10.3847/1538-4357/adbf94}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {73}, shortjournal = {The Astrophys. J.}, title = {Central velocity dispersion as the primary driver of abundance patterns in quenched galaxies}, volume = {984}, year = {2025}, }
• (2025). Dust destruction in shock waves in the cygnus loop. ApJ, 984(1), 72. (www)

  @article{ , abstract = {Supernova remnant (SNR) shock waves are known to be important sources of dust destruction in the interstellar medium. Models of dust destruction in shocks have made various predictions of the destruction efficiency, but have generally been difficult to test in detail due to the uncertainties in the physical parameters in observed shocks and the required assumptions in the models. In this paper we present new Hubble Space Telescope data on shocks in the Cygnus Loop SNR that have been observed with enough precision over time to allow determination of their proper motions and thus the shock speeds. The observed UV emission comes from various ions from elements that are prevalent in dust. We present results of new models for these radiative shocks that include dust destruction, including the liberation of elements into the gas phase. The inclusion of sputtered grain material substantially alters the predicted cooling and spectra and gives us a better estimate of the effects of dust on the shock emission. The observed line ratios strongly support the predictions that radiative shocks with speeds v s = 90–160 km s −1 destroy dust with an efficiency that increases with shock speed approximately with the predicted rates.}, archive = {J_ApJ}, author = {Jonathan D. Slavin and John C. Raymond}, doi = {10.3847/1538-4357/adbffe}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {72}, shortjournal = {The Astrophys. J.}, title = {Dust destruction in shock waves in the cygnus loop}, volume = {984}, year = {2025}, }
• (2025). The immediate, exemplary, and fleeting echelle spectroscopy of SN 2023ixf: Monitoring acceleration of slow progenitor circumstellar material driven by shock interaction. ApJ, 984(1), 71. (www)

  @article{ , abstract = {We present high-resolution WIYN/NEID echelle spectroscopy ( R ≈ 70,000) of the supernova (SN) 2023ixf in M101, obtained 1.51 to 18.51 days after explosion over nine epochs. Daily monitoring for the first 4 days after explosion shows narrow emission features (≤200 km s −1 ), exhibiting predominantly blueshifted velocities that rapidly weaken, broaden, and vanish in a manner consistent with radiative acceleration and the SN shock eventually overrunning or enveloping the full extent of the dense circumstellar medium (CSM). The most rapid evolution is in the He i emission, which is visible on day 1.51 but disappears by day 2.62. We measure the maximum pre-SN speed of He i to be 25 {}_{-5}^{+0}\,\pm 2 km s −1 , where the error is attributable to the uncertainty in how much the He i had already been radiatively accelerated and to measurement of the emission-line profile. The radiative acceleration of CSM is likely driven by the shock–CSM interaction, and the CSM is accelerated to ≥200 km s −1 before being completely swept up by the SN shock to ∼2000 km s −1 . We compare the observed spectra with spherically symmetric r1w6b HERACLES/CMFGEN model spectra and find the line evolution to generally be consistent with radiative acceleration, optical depth effects, and evolving ionization state. The progenitor of SN 2023ixf underwent an enhanced mass-loss phase ≳4 yr prior to core collapse, creating a dense, asymmetric CSM region extending out to approximately r CSM = 3.7 × 10 14 ( v shock /9500 km s −1 ) cm.}, archive = {J_ApJ}, author = {Danielle Dickinson and Dan Milisavljevic and Braden Garretson and Luc Dessart and Raffaella Margutti and Ryan Chornock and Bhagya Subrayan and D. John Hillier and Eli Golub and Dan Li and Sarah E. Logsdon and Jayadev Rajagopal and Susan Ridgway and Nathan Smith and Chuck Cynamon}, doi = {10.3847/1538-4357/adc108}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {71}, shortjournal = {The Astrophys. J.}, title = {The immediate, exemplary, and fleeting echelle spectroscopy of SN 2023ixf: Monitoring acceleration of slow progenitor circumstellar material driven by shock interaction}, volume = {984}, year = {2025}, }
• (2025). Estimating the bulk velocity of energetic particle populations using IS⊙IS/EPI-lo measurements. ApJ, 984(1), 70. (www)

  @article{ , abstract = {We introduce a method to derive the bulk velocity of the solar energetic particle population, given intensity measurements for a set of apertures viewing half of the sky, as is the case for energetic particle measurements from IS⊙IS/EPI-Lo on the Parker Solar Probe spacecraft. In the comoving frame, intensity distribution is modeled as an isotropic power-law energy spectrum multiplied by an arbitrary pitch angle distribution. This distribution is shifted by an arbitrary bulk velocity vector, then converted to expectation values for the particle counts that would be observed by the instrument. By assuming that the observed particle counts are Poisson-distributed samples of the model, a maximum likelihood bulk velocity is found. To test the method, we used simulated measurements to explore the reliability of the method. We found that, even with half-sky measurements, the method can provide nearly unbiased estimates of the bulk velocity within the uncertainty as long as the pitch angle distribution is resolved. We also took advantage of a period during which the spacecraft was rolling for calibration purposes, effectively giving EPI-Lo full-sky viewing. By comparing the result obtained from different segments of the sky, we found that those obtained from different half-sky fields of view are generally compatible within the uncertainty, especially when the pitch angle distribution is resolved. We also compared the perpendicular part of the bulk energetic velocity to the perpendicular part of the bulk solar wind velocity, finding a strong correlation (∼0.78), as expected.}, archive = {J_ApJ}, author = {H. A. Farooki and M. E. Cuesta and R. Bandyopadhyay and G. Livadiotis and D. J. McComas and J. S. Rankin and M. M. Shen and J. R. Szalay}, doi = {10.3847/1538-4357/adc12b}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {70}, shortjournal = {The Astrophys. J.}, title = {Estimating the bulk velocity of energetic particle populations using IS⊙IS/EPI-lo measurements}, volume = {984}, year = {2025}, }
• (2025). Velocity and density fluctuations in the quiet sun corona. ApJ, 984(1), 69. (www)

  @article{ , abstract = {We investigate the properties and relationship between Doppler velocity fluctuations and intensity fluctuations in the off-limb quiet Sun corona. These are expected to reflect the properties of Alfvénic and compressive waves, respectively. The data come from the Coronal Multichannel Polarimeter (COMP). These data were studied using spectral methods to estimate the power spectra, amplitudes, perpendicular correlation lengths, phases, trajectories, dispersion relations, and propagation speeds of both types of fluctuations. We find that most velocity fluctuations are due to Alfvénic waves but that intensity fluctuations come from a variety of sources, likely including fast and slow mode waves, as well as aperiodic variations. The relation between the velocity and intensity fluctuations differs depending on the underlying coronal structure. On short closed loops, the velocity and intensity fluctuations have similar power spectra and speeds. In contrast, on longer nearly radial trajectories, the velocity and intensity fluctuations have different power spectra, with the velocity fluctuations propagating at much faster speeds than the intensity fluctuations. Considering the temperature sensitivity of COMP, these longer structures are more likely to be closed fields lines of the quiet Sun rather than cooler open field lines. That is, we find the character of the interactions of Alfvénic waves and density fluctuations depends on the length of the magnetic loop on which they are traveling.}, archive = {J_ApJ}, author = {Michael Hahn and Xiangrong Fu and Stefan J. Hofmeister and Yifan Huang and Alexandros Koukras and Daniel Wolf Savin}, doi = {10.3847/1538-4357/adc1c0}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {69}, shortjournal = {The Astrophys. J.}, title = {Velocity and density fluctuations in the quiet sun corona}, volume = {984}, year = {2025}, }
• (2025). CWTHF: Identifying dark matter halos with continuous wavelet transform. ApJ, 984(1), 68. (www)

  @article{ , abstract = {Cosmological simulations are an important method for investigating the evolution of the Universe. In order to gain further insight into the processes of structure formation, it is necessary to identify isolated bound objects within the simulations, namely, the dark matter halos. The continuous wavelet transform (CWT) is an effective tool used as a halo finder due to its ability to extract clustering information from the input data. In this study, we introduce the continuous wavelet transform halo finder (CWTHF), the first wavelet-based, MPI-parallelized halo finder, marking a novel approach in the field of cosmology. We calculate the CWT from the cloud-in-cell grid and segment the grid based on the local CWT maxima. We then investigate the effects of the parameters that influence our program and identify the default settings. A comparison with the conventional friends-of-friends (FOF) method demonstrates the viability of CWT for halo finding. Although the actual performance is not faster than FOF, the linear time complexity of { \mathcal O }(N) of our identification scheme indicates its significant potential for future optimization and application.}, archive = {J_ApJ}, author = {Minxing Li and Yun Wang and Ping He}, doi = {10.3847/1538-4357/adc440}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {68}, shortjournal = {The Astrophys. J.}, title = {CWTHF: Identifying dark matter halos with continuous wavelet transform}, volume = {984}, year = {2025}, }
• (2025). Six-hour prediction of interplanetary magnetic field bz profiles for strong southward cases by deep learning. ApJ, 984(1), 67. (www)

  @article{ , abstract = {In this study, we develop deep learning models to forecast the 6 hr interplanetary magnetic field (IMF) B z component for southward cases. The models are based on a bidirectional long short-term memory method, and input parameters are solar wind data ( V , N , T ) and IMF components ( B t , B x , B y , B z ). The data are obtained from OMNI, whose period is from 2000 to 2022. We use the preceding 12 hr of data as input and the subsequent 6 hr of B z data as target. To focus on strong geomagnetic conditions, we consider periods where B z values drop below the negative standard deviation (approximately −3 nT) for at least 6 hr. The models are trained and validated using a 12-fold cross-validation process, with each model trained over 8 months of data and tested over 4 months. The ensemble model, which averages 12-fold model results, achieves an RMSE ranging from 1.75 (30 minutes prediction) to 2.55 nT (6 hr prediction), significantly outperforming two baseline methods: multilayer perceptron and multiple linear regression. Our model can capture both decreasing and increasing phases of B z , showing reliable performance across varying geomagnetic conditions. Our results suggest a sufficient possibility for predicting B z under noticeable southward conditions. We expect that our model can be used for subsequent space weather predictions, such as global magnetohydrodynamic simulations in the magnetosphere.}, archive = {J_ApJ}, author = {Jihyeon Son and Yong-Jae Moon and Young-Sil Kwak and Kyung Sun Park and Hyun-Jin Jeong}, doi = {10.3847/1538-4357/adc445}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {67}, shortjournal = {The Astrophys. J.}, title = {Six-hour prediction of interplanetary magnetic field bz profiles for strong southward cases by deep learning}, volume = {984}, year = {2025}, }
• (2025). Orbital phase shifts of type-I outbursts in EXO 2030+375. ApJ, 984(1), 66. (www)

  @article{ , abstract = {EXO 2030+375 is a peculiar high-mass X-ray binary that has been exhibiting Type-I outburst activities consistently over the past decades. The phases of outburst peaks are generally stable and occur near the orbital periastron. However, significant orbital phase shifts have occasionally been observed in 1995, 2006, and 2016. In this paper, we report another orbital phase shift triggered by a giant outburst in 2021. During this event, the orbital phase of Type-I outburst peaks changed dramatically, moving from near periastron to 20 days after periastron, followed by a gradual recovery. Additionally, for several cycles after the 2021 giant outburst, some Type-I outbursts were missing, with subsequent outbursts occurring every two orbits. We discuss our observations in the frame of the precession of an eccentric Be disk.}, archive = {J_ApJ}, author = {Run-Ting Huang and Long Ji and Jing-Zhi Yan}, doi = {10.3847/1538-4357/adc573}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {66}, shortjournal = {The Astrophys. J.}, title = {Orbital phase shifts of type-I outbursts in EXO 2030+375}, volume = {984}, year = {2025}, }
• (2025). Asteroseismology of long-period variables with OGLE-IV data: Using global seismic parameters as luminosity indicators. ApJ, 984(1), 65. (www)

  @article{ , abstract = {Long-period variables (LPVs) are high-luminosity red giants or supergiants with pulsation periods ranging from days to years. Many LPVs in the Large Magellanic Cloud (LMC) and Galactic bulge (BLG) have been continuously observed over a time span of 26 yr by the Optical Gravitational Lensing Experiment (OGLE) survey. Using OGLE-IV data, we applied Gaussian processes with kernels tailored for solar-like oscillations to extract two global asteroseismic parameters—the frequency of maximum power ( {\nu }_{{\rm{\max }}} ) and the large frequency separation (Δ ν )—for LPVs with primary mode periods ( P 1) between 10 and 100 days in the LMC and BLG. We found that the {\nu }_{{\rm{\max }}} -Δ ν relation for LPVs in this work aligns with that of lower-luminosity Kepler red giants, confirming that the pulsations of these LPVs are likely solar like. We found that {\nu }_{{\rm{\max }}} and Δ ν can serve as luminosity indicators. Compared to P 1, {\nu }_{{\rm{\max }}} and Δ ν exhibit significantly tighter correlations with the absolute magnitude in the Two Micron All Sky Survey K s band ( M K ), with corresponding scatter of 0.27 and 0.21 mag, respectively. Using the calibrated {\nu }_{{\rm{\max }}} – M K and Δ ν – M K relations for LPVs in the LMC, we determined the M K values for individual stars in the BLG. By accounting for extinction, we further calculated the distances to 4948 BLG stars. The peak of the resulting distance distribution corresponds to an estimated distance to the Galactic center of approximately 9.1 kpc, which appears to be overestimated, suggesting that the seismic luminosity relation calibrated from the LMC may not be directly applicable to BLG stars.}, archive = {J_ApJ}, author = {Qiang Xiong and Tanda Li and Jie Yu and Zhiwen Li and Shaolan Bi and Xianfei Zhang and Haibo Yuan and I. Soszyński and A. Udalski and M. K. Szymański and D. M. Skowron and J. Skowron and P. Pietrukowicz and R. Poleski and S. Kozłowski and P. Mróz and K. Ulaczyk and K. Rybicki and P. Iwanek and M. Wrona and M. Gromadzki and M. Mróz}, doi = {10.3847/1538-4357/adc603}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {65}, shortjournal = {The Astrophys. J.}, title = {Asteroseismology of long-period variables with OGLE-IV data: Using global seismic parameters as luminosity indicators}, volume = {984}, year = {2025}, }
• (2025). The timing and polarization of PSR j0002+6216. ApJ, 984(1), 64. (www)

  @article{ , abstract = {The combined timing analysis of data from the Five-hundred-meter Aperture Spherical radio Telescope (FAST) and the Fermi Large Area Telescope confirmed that PSR J0002+6216 is not a hyper-velocity (exceeding 1000 km s −1 ) pulsar. From this analysis, we determined the total proper motion of PSR J0002+6216 to be μ tot = 39.05 ± 15.79 mas yr −1 , which is consistent with Very Long Baseline Interferometry (VLBI) measurements to within 0.24 σ . Moreover, two glitches were detected for the first time, which occurred on MJD 58850(17) and MJD 60421(6), respectively. The second glitch exhibited an exponential recovery process, with Q = 0.0090(3) and τ d = 45(3) days. Additionally, with FAST high-sensitivity observations, we measured the interstellar rotation measure (RM) and the 3D orientation of the spin axis for the first time, and updated the dispersion measure (DM) of PSR J0002+6216. Currently, no variations in RM or DM have been detected. By combining the measured RM with the observed position angle of the spin axis, we determined that the intrinsic position angle of the pulsar's spin axis is {\psi }_{0}(\mathrm{intrinsic})=89\mathop{.}\limits^{^\circ }9\pm 4\mathop{.}\limits^{^\circ }6 . When we compared this with the proper motion position angle obtained from VLBI, we found a misalignment of approximately 23 ∘ between the spin and velocity angles of PSR J0002+6216. At present, pulsars with 2D spin–velocity angle measurements are unable to fully test the Janka et al. model. However, with more high-precision observational data in the future, we will be able to further test models related to pulsar birth.}, archive = {J_ApJ}, author = {Y. Wei and N. Wang and J. P. Yuan and J. M. Yao and M. Y. Ge and S. J. Dang and D. Zhao and F. F. Kou and P. Liu and J. T. Bai}, doi = {10.3847/1538-4357/adc714}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {64}, shortjournal = {The Astrophys. J.}, title = {The timing and polarization of PSR j0002+6216}, volume = {984}, year = {2025}, }
• (2025). The nature of gravitational wave events with host environment escape velocities. ApJ, 984(1), 63. (www)

  @article{ , abstract = {We propose a novel method to probe the parameters and origin channels of gravitational wave events using the escape velocities of their host environments. This method could lead to more convergent posterior distributions offering additional insights into the physical properties, formation, and evolution of the sources. The method provides more accurate parameter estimation for events that represent previous mergers in the hierarchical triple merger scenario and is valuable for the search for such mergers with third-generation ground-based detectors. To demonstrate this approach, we take six recently identified events in LIGO–Virgo–KAGRA (LVK) data, considered as potential previous mergers in hierarchical triple mergers, as examples. The use of escape velocities results in posterior spin distributions that are concentrated near zero, aligning with the expected birth spins of first-generation black holes formed from the collapse of stars. The uncertainty in the posterior primary mass distribution is significantly reduced comparing with the LVK distributions, especially for events modeled under the assumption of a globular cluster (GC) origin scenario. We rule out the possibility that GW190512, GW170729, and GW190708 originate from GCs as previous mergers in the hierarchical triple merger scenario.}, archive = {J_ApJ}, author = {Guo-Peng Li and Xi-Long Fan}, doi = {10.3847/1538-4357/adc7bb}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {63}, shortjournal = {The Astrophys. J.}, title = {The nature of gravitational wave events with host environment escape velocities}, volume = {984}, year = {2025}, }
• (2025). Reacceleration of a c iv broad absorption line in quasar SDSS j083817.00+295526.5. ApJ, 984(1), 62. (www)

  @article{ , abstract = {We present a rare signature of reacceleration in a C iv broad absorption line (BAL) of the quasar SDSS J083817.00+295526.5. This quasar showcases three distinct BAL systems, labeled as systems A, B, and C. Notably, system A, which boasts the highest velocity of ∼−22,000 km s −1 , initially demonstrates a deceleration of ∼3160 km s −1 in its C iv ion over a rest-frame period of ∼2.3 yr. Subsequently, it exhibits an acceleration of ∼−3366 km s −1 over a rest-frame period of ∼2.6 yr. To elucidate the nature of these signatures, we conducted a thorough analysis, focusing on the ionization state, location, and variation situation of the three BAL systems. Our findings reveal that system A exhibits higher velocities, higher ionization states, and is situated closer to the central source compared to systems B and C. Collectively, these characteristics suggest that the outflow generating system A is located in an exceptionally extreme environment and experiences more pronounced impacts from background radiation energy than systems B and C. Given the currently limited observational data, the physical origin of this peculiar reacceleration phenomenon remains an open question. We briefly discuss several possibilities and hypothesize that the outflow winds initially interact with ambient galactic material, causing their deceleration, and are subsequently reaccelerated by the radiation pressure from the central source.}, archive = {J_ApJ}, author = {Ying-Ru Lin and Wei-Jian Lu}, doi = {10.3847/1538-4357/adc99c}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {62}, shortjournal = {The Astrophys. J.}, title = {Reacceleration of a c iv broad absorption line in quasar SDSS j083817.00+295526.5}, volume = {984}, year = {2025}, }
• (2025). A search for low-mass neutron stars in the third observing run of advanced LIGO and virgo. ApJ, 984(1), 61. (www)

  @article{ , abstract = {Most observed neutron stars have masses around 1.4 M ⊙ , consistent with current formation mechanisms. To date, no subsolar-mass neutron star has been observed. Observing one would provide crucial constraints on the nuclear equation of state, unveil a new neutron star population, and advance understanding of their formation mechanisms. We present the first targeted search for tidally deformed subsolar-mass binary neutron stars (BNSs), with primary masses ranging from 0.1 to 2 M ⊙ and secondary masses from 0.1 to 1 M ⊙ , using data from the third observing run of the Advanced LIGO and Virgo gravitational-wave detectors. We account for the tidal deformabilities of up to O (10 4 ) of these systems, as low-mass neutron stars are more easily distorted by their companions. Previous searches that neglect tidal deformability lose sensitivity to low-mass sources, potentially missing more than ∼30% of detectable signals from a system with a chirp mass of 0.6 M ⊙ binaries. No statistically significant detections were made. In the absence of a detection, we place a 90% confidence upper limit on the local merger rate for subsolar BNSs, constraining it to be <6.4 × 10 4 Gpc −3 yr −1 for a chirp mass of 0.2 M ⊙ and <2.2 × 10 3 Gpc −3 yr −1 for 0.7 M ⊙ . With future upgrades to detector sensitivity, development of next-generation detectors, and ongoing improvements in search pipelines, constraints on the minimum mass of neutron stars will improve, providing the potential to constrain the nuclear equation of state, reveal new insights into neutron star formation channels, and potentially identify new classes of stars.}, archive = {J_ApJ}, author = {Keisi Kacanja and Alexander H. Nitz}, doi = {10.3847/1538-4357/adc9a5}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {61}, shortjournal = {The Astrophys. J.}, title = {A search for low-mass neutron stars in the third observing run of advanced LIGO and virgo}, volume = {984}, year = {2025}, }
• (2025). Shock-cooling constraints via early-time observations of the type IIb SN 2022hnt. ApJ, 984(1), 60. (www)

  @article{ , abstract = {We report the results of a rapid follow-up campaign on the Type IIb supernova (SN) 2022hnt. We present a daily, multiband, photometric follow-up using the Las Cumbres Observatory, the Zwicky Transient Facility, the orbiting Swift observatory, and the Asteroid Terrestrial-impact Last Alert System. A distinctive feature in the light curve of SN 2022hnt and other IIb SNe is an early narrow peak prior to the 56 Ni peak caused by rapid shock cooling of the hydrogen envelope, which can serve as an important probe of the properties of the massive progenitor star in the moments before explosion. Using SN 2022hnt as a case study, we demonstrate a framework of considerations for the application of shock cooling models to type IIb SNe, outlining a consistent procedure for future surveys of Type IIb SNe progenitor and explosion properties. We fit several recent models of shock-cooling emission and obtain progenitor radii between ∼50 and ∼100 R ⊙ , as well as hydrogen-enriched envelope masses between ∼0.01 and ∼0.1 M ⊙ , both consistent with values for other IIb SNe. One of these models is the model of J. Morag et al., marking the first time this model has been applied to a Type IIb SN. Finally, we evaluate contrasting predictions between shock-cooling models to construct a fiducial parameter set that can be used for comparison to other SNe.}, archive = {J_ApJ}, author = {Joseph R. Farah and D. Andrew Howell and Giacomo Terreran and Ido Irani and Jonathan Morag and Craig Pellegrino and Curtis McCully and Megan Newsome and Estefania Padilla Gonzalez and K. Azalee Bostroem and Griffin Hosseinzadeh and Moira Andrews and Logan Prust and Daichi Hiramatsu}, doi = {10.3847/1538-4357/adad5a}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {60}, shortjournal = {The Astrophys. J.}, title = {Shock-cooling constraints via early-time observations of the type IIb SN 2022hnt}, volume = {984}, year = {2025}, }
• (2025). Dark matter genesis. ApJ, 984(1), 59. (www)

  @article{ , abstract = {Recent discoveries of primordial black hole (PBH) candidates by means of high-cadence microlensing open the way to a physical understanding of the formation of dark matter as a chapter in the thermal history of the Universe. Two complementary sites of PBH formation are considered, inflation and the early Universe at TeV to MeV energies. In the latter case the Friedmann equation, together with mass measurements, reveal the threshold energy, the mass spectrum, and the likely end point of this epoch. Some of the many recent exoplanet detections may conceivably have been detections of PBHs. When the Universe cools to MeV temperatures, larger-mass PBHs would form similarly, reaching the supermassive regime. The discovery of numerous supermassive black holes at high redshift with JWST fulfils this expectation. We corroborate the idea that Planck mass relics could be an important component of dark matter, and find that these are formed by PBHs with initial mass less than approximately 6 × 10 −16 M ⊙ and cosmic temperature above 10 9 GeV. Although in some mass ranges PBHs can only make up a modest fraction of Ω m , it is possible that all astrophysical dark matter, as distinct from axions and weakly interacting massive particles, is of PBH origin.}, archive = {J_ApJ}, author = {Jeremy Mould}, doi = {10.3847/1538-4357/adaebe}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {59}, shortjournal = {The Astrophys. J.}, title = {Dark matter genesis}, volume = {984}, year = {2025}, }
• (2025). Gaia net: Toward robust spectroscopic parameters of stars of all evolutionary stages. ApJ, 984(1), 58. (www)

  @article{ , abstract = {We present a new processing of XP spectra for 220 million stars released in Gaia DR3. The new data model is capable of handling objects with T eff between 2000 and 50,000 K and with \mathrm{log}\,g between 0 and 10, including objects of multitude of masses and evolutionary stages. This includes for the first time ever robust processing of spectroscopic parameters for pre-main-sequence stars, with \mathrm{log}\,g sensitivity toward their age. Through this analysis we examine the distribution of young low-mass stars with ages of up to 20 Myr in the solar neighborhood, and we identify a new massive (>1000 stars) population, Ophion, which is found east of Sco–Cen. This population appears to be fully disrupted, with negligible kinematic coherence. Nonetheless, due its young age it appears to still persist as a spatial overdensity. Through improved determination of ages of the nearby stars, it may be possible to better recover the star-forming history of the solar neighborhood outside of the moving groups.}, archive = {J_ApJ}, author = {Dylan Huson and Indiana Cowan and Logan Sizemore and Marina Kounkel and Brian Hutchinson}, doi = {10.3847/1538-4357/adc2fa}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {58}, shortjournal = {The Astrophys. J.}, title = {Gaia net: Toward robust spectroscopic parameters of stars of all evolutionary stages}, volume = {984}, year = {2025}, }
• (2025). HST grism observations of a z ∼ 1.8 cluster candidate from the clusters occupied by bent radio AGN (COBRA) survey. ApJ, 984(1), 57. (www)

  @article{ , abstract = {We present new Hubble Space Telescope/Wide Field Camera 3 G141 grism observations for COBRA 1411+3415, originally identified as a high-redshift cluster candidate in the Clusters Occupied by Bent Radio AGN (COBRA) survey using radio, infrared, and optical data. We spectroscopically identify seven cluster members within a 0.5 Mpc radius with grism redshifts in the range 1.8006 ≤ z grism ≤ 1.8175, consistent with COBRA 1411+3415 being a high-redshift cluster with a mean redshift of 〈 z grism 〉 = 1.8106 ± 0.0006. The detection of seven galaxies within this small redshift range is significant above the background distribution of galaxies at the level of 5 σ . The line-of-sight velocity dispersion of the cluster is found to be σ ∥ = {701}_{-138}^{+347} km s −1 with a virial mass of M 200 ≈ 2.{2}_{-1.3}^{+3.3} × 10 14 M ⊙ . However, the mass may be lower if the cluster is still in formation. In projected phase space, we also identify two possible infalling members of COBRA 1411+3415 and two additional structures at z ∼ 1.73 and z ∼ 1.88. The similar spatial distributions and small projected separation from the main cluster suggest they could be a part of the same large-scale filament and together may form a protocluster system that could eventually merge to form a single, massive cluster. COBRA 1411+3415 is the highest-redshift cluster to be spectroscopically confirmed using a bent, double-lobed radio source as a cluster tracer.}, archive = {J_ApJ}, author = {Courtney B. Watson and Elizabeth L. Blanton and Emmet Golden-Marx and Matthew L. N. Ashby and Scott W. Randall and J. D. Wing and E. M. Douglass}, doi = {10.3847/1538-4357/adc410}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {57}, shortjournal = {The Astrophys. J.}, title = {HST grism observations of a z ∼ 1.8 cluster candidate from the clusters occupied by bent radio AGN (COBRA) survey}, volume = {984}, year = {2025}, }
• (2025). The impact of the galactic bar and the large magellanic cloud on hypervelocity star trajectories. ApJ, 984(1), 56. (www)

  @article{ , abstract = {Hypervelocity stars (HVSs) ejected from the Galactic center at speeds faster than the Galactic escape velocity are useful tools to provide insight into the Milky Way's dark matter halo. However, most characterizations of HVS orbits assume static models of the Milky Way's gravitational potential. In this work, we assess the influence of the Galactic bar and the Large Magellanic Cloud (LMC) on HVS trajectories, comparing them with those from an axisymmetric potential. We simulate 28,000 HVSs ejected over the last 100 Myr and find that ignoring the bar and LMC can cause their apparent ejection location to drift by up to 100 pc. Applying two standard HVS potential fitting methods to our sample shows that they are unable to perform as designed when nonaxisymmetric effects are neglected. We calculate the angle between HVS Galactocentric position and velocity, and find the LMC and bar can induce a deflection angle of up to several degrees. Using mock Gaia Data Release 4 observations, however, we show that this deflection is too small in magnitude to be measured in the near future without significantly improved observational uncertainties, particularly in heliocentric distance. Our results emphasize the need to account for the bar and LMC in modeling the Galactic potential using HVSs as a tracer.}, archive = {J_ApJ}, author = {Isabella Armstrong and Fraser A. Evans and Jo Bovy}, doi = {10.3847/1538-4357/adc449}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {56}, shortjournal = {The Astrophys. J.}, title = {The impact of the galactic bar and the large magellanic cloud on hypervelocity star trajectories}, volume = {984}, year = {2025}, }
• (2025). Prospects for detecting cosmic filaments in lyα emission across redshifts z = 2–5. ApJ, 984(1), 55. (www)

  @article{ , abstract = {The standard ΛCDM cosmological model predicts that a large amount of diffuse neutral hydrogen distributes in cosmic filaments, which could be mapped through Ly α emission observations. We use the hydrodynamical simulation Illustris-TNG50 to investigate the evolution of surface brightness (SB) and detectability of neutral hydrogen in cosmic filaments across redshifts z = 2–5. While the H i column density of cosmic filaments decreases with redshift, due to the rising temperature with cosmic time in filaments, the SB of Ly α emission in filaments is brighter at lower redshifts, suggesting that the detection of cosmic filaments is more feasible at lower redshifts. However, most of the Ly α emission from cosmic filaments is around 10 −21 \mathrm{erg}\,{{\rm{s}}}^{-1}\,{\mathrm{cm}}^{-2}\,{\mathrm{arsec}}^{-2} , making it extremely challenging to detect with current observational instruments. We further generate mock images using the Multi-Unit Spectroscopic Explorer (MUSE) spectrograph installed on the Very Large Telescope (VLT) and a MUSE-like spectrograph on the upcoming Extremely Large Telescope (ELT). Our finding indicates that while the VLT can only detect filamentary structures made of dense gas in galactic centers, the ELT is expected to reveal much finer filamentary structures from diffuse neutral hydrogen outside of galaxies. Compared to the VLT, both the number density and the longest length of filaments are greatly boosted with the ELT. Hence the forthcoming ELT is highly promising to provide a clearer view of cosmic filaments in Ly α emission.}, archive = {J_ApJ}, author = {Yizhou Liu and Liang Gao and Shihong Liao and Kai Zhu}, doi = {10.3847/1538-4357/adc44b}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {55}, shortjournal = {The Astrophys. J.}, title = {Prospects for detecting cosmic filaments in lyα emission across redshifts z = 2–5}, volume = {984}, year = {2025}, }
• (2025). An NGC 1068-informed understanding of neutrino emission of the active galactic nucleus TXS 0506+056. ApJ, 984(1), 54. (www)

  @article{ , abstract = {We present arguments that the neutrinos observed by IceCube from the active galactic nucleus TXS 0506+056 may originate near its core and not in the blazar jet. The origin of the neutrinos is consistent with the mechanism that produces the neutrino flux observed from the active galaxies NGC 1068 and NGC 4151, but requires an Eddington luminosity cosmic-ray flux to compensate for its larger distance. Like NGC 1068, the source is characterized by episodes of high X-ray emission and is gamma-ray-obscured during the 2014 burst, and there is evidence that this is also the case during the short burst in 2017 that produced IC-170922. The observations may be explained as a flux originating in an obscured core within 10 ∼ 100 Schwarzschild radii from the central black hole, which is not transparent to gamma rays from the decay of neutral pions accompanying the neutrinos.}, archive = {J_ApJ}, author = {Arifa Khatee Zathul and Marjon Moulai and Ke Fang and Francis Halzen}, doi = {10.3847/1538-4357/adc44d}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {54}, shortjournal = {The Astrophys. J.}, title = {An NGC 1068-informed understanding of neutrino emission of the active galactic nucleus TXS 0506+056}, volume = {984}, year = {2025}, }
• (2025). The impact of accretion on FRB radiation mechanisms in binary systems: Constraints and implications. ApJ, 984(1), 53. (www)

  @article{ , abstract = {Fast radio bursts (FRBs) are intense, millisecond-duration radio transients that have recently been proposed to arise from coherent radiation mechanisms within the magnetosphere of neutron stars. Observations of repeating FRBs, including periodic activity and large variations in Faraday rotation measures, suggest that these bursts may have binary system origins, with a massive companion. In this work, we investigate how accretion from a massive companion influences the FRB radiation within the magnetosphere of the neutron star. Focusing on two widely accepted pulsar-like coherent radiation mechanisms, we establish the parameter space for neutron stars that allows FRB generation, even in the presence of accreted matter. Our analysis shows that coherent curvature radiation is only viable within a narrow range of parameters, while the magnetic reconnection mechanism operates across a broader range. In both cases, the neutron star must possess a strong magnetic field with strength ≳10 13 G. These findings at least indicate that the central engines responsible for producing observable FRBs in binary systems are indeed magnetars.}, archive = {J_ApJ}, author = {Gong-Yu Yao and Can-Min Deng}, doi = {10.3847/1538-4357/adc574}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {53}, shortjournal = {The Astrophys. J.}, title = {The impact of accretion on FRB radiation mechanisms in binary systems: Constraints and implications}, volume = {984}, year = {2025}, }
• (2025). Unveiling bifurcated blue straggler sequences in NGC 2173: Insights from binary evolution. ApJ, 984(1), 52. (www)

  @article{ , abstract = {Identifying bifurcated blue straggler (BS) sequences in color–magnitude diagrams (CMDs) of star clusters has long been regarded as a powerful diagnostic for distinguishing different BS formation mechanisms. While such bifurcations are typically associated with core-collapsed clusters, their detection in dynamically young clusters raises new questions about their origins. In this study, using high-precision proper motion data derived from Hubble Space Telescope multiepoch observations, we confirm the existence of two distinct BS sequences in the Large Magellanic Cloud cluster NGC 2173 (∼1.58 Gyr): a well-defined, narrow blue sequence and a sparser red sequence. The extended core region excludes collisional formation as a viable channel for BS formation. Our binary evolution models suggest that nonconservative mass transfer (MT) is essential for shaping the distribution of BS binaries in the CMD. The red sequence primarily comprises BS binaries formed through conservative ongoing MT. In contrast, the blue sequence BS binaries are formed through nonconservative post-MT processes, all involving white dwarf (WD) companions. These BS+WD binary systems may subsequently undergo a second MT phase, leading to the formation of double WD systems.}, archive = {J_ApJ}, author = {Li Wang and Dengkai Jiang and Chengyuan Li and Licai Deng and Antonino P. Milone and Long Wang}, doi = {10.3847/1538-4357/adc575}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {52}, shortjournal = {The Astrophys. J.}, title = {Unveiling bifurcated blue straggler sequences in NGC 2173: Insights from binary evolution}, volume = {984}, year = {2025}, }
• (2025). Methods for tracking cosmic-ray spectral changes using neutron monitors at high cutoff rigidity. ApJ, 984(1), 51. (www)

  @article{ , abstract = {Neutron monitors are a standard tool for high-precision monitoring of changes in the Galactic cosmic ray (GCR) flux that occur as a result of variations of the heliospheric conditions and solar storms. In Thailand, we have developed a mobile neutron monitor named "Changvan" based on the 3NM64 design, except that the middle counter lacks lead producer rings, so we call it a semileaded neutron monitor. From 2021 April to 2023 April, the Changvan operated at the Science and Technology Park, Mae Hia, Chiang Mai, Thailand, at an altitude of about 340 m above sea level, with a vertical cutoff rigidity of 16.7 GV, which is near the highest value observed globally. With a similar cutoff rigidity, the nearby Princess Sirindhorn Neutron Monitor is an 18NM64 at the summit of Doi Inthanon, the highest mountain in Thailand, at 2560 m above sea level. We examine how count rates at different altitudes with similar cutoffs, count rates from the unleaded versus leaded counters, and the leader fraction measured from time-delay histograms all reflect GCR spectral differences, thus providing a variety of techniques for tracking cosmic-ray spectral changes. Applied at high cutoff rigidity, these methods extend the reach of the worldwide neutron monitor network to even higher rigidity.}, archive = {J_ApJ}, author = {S. Khamphakdee and W. Nuntiyakul and C. Banglieng and A. Seripienlert and P. Yakum and A. Sáiz and D. Ruffolo and P. Evenson and K. Munakata and S. Komonjinda}, doi = {10.3847/1538-4357/adc5f9}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {51}, shortjournal = {The Astrophys. J.}, title = {Methods for tracking cosmic-ray spectral changes using neutron monitors at high cutoff rigidity}, volume = {984}, year = {2025}, }
• (2025). Comparative analysis of hall effect implementations in hall magnetohydrodynamics. ApJ, 984(1), 50. (www)

  @article{ , abstract = {There is no standard numerical implementation of the Hall effect, which is one of the nonideal magnetohydrodynamic (MHD) effects. Numerical instability arises when a simple implementation is used, in which the Hall electric field is added to the electric field to update magnetic fields without further modifications to the numerical scheme. In this paper, several implementations proposed in the literature are compared to identify an approach that provides stable and accurate results. We consider two types of implementations of the Hall effect. One is a modified version of the Harten–Lax–van Leer method (H all -HLL), in which the phase speeds of whistler waves are adopted as the signal speeds; the other involves adding a fourth-order hyper-resistivity to a Hall-MHD code. Based on an extensive series of test calculations, we find that hyper-resistivity yields more accurate results than H all -HLL, particularly in problems where the whistler wave timescale is shorter than the timescales of the physical processes of interest. Through both von Neumann stability analysis and numerical experiments, an appropriate coefficient for the hyper-resistivity is determined.}, archive = {J_ApJ}, author = {Kazunari Iwasaki and Kengo Tomida}, doi = {10.3847/1538-4357/adc2f7}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {50}, shortjournal = {The Astrophys. J.}, title = {Comparative analysis of hall effect implementations in hall magnetohydrodynamics}, volume = {984}, year = {2025}, }
• (2025). A spatiotemporal data cube approach to classification of variable stars: A catalog of candidate variable stars from the TESS full-frame image raw data. ApJ, 984(1), 49. (www)

  @article{ , abstract = {We present a novel technique to identify variable stars in large surveys that performs classification not on the 1D light curves but on the spatiotemporal data cube. Such an approach can allow the model to better discriminate against the systematics in the background flux and consider the variability across the entire point-spread function, which can be advantageous to large surveys such as Transiting Exoplanet Survey Satellite (TESS). We perform a search for eclipsing, pulsating, and rotating variables in TESS full-frame images. This classification was done using a neural network that has been trained on variable stars identified in other surveys. In total we identify 3.1 million candidate variable sources. Although these sources should undergo significant vetting to confirm them using more traditional techniques, through assembling the catalog of the most promising candidates, it should be possible to significantly narrow down the list of light curves of sources that would need to be constructed for such an analysis. With an increasing number of surveys aiming to do photometric monitoring coming online in the future (e.g., LSST), a similar analysis with an improved training set could be advantageous in classifying variable stars.}, archive = {J_ApJ}, author = {Harry Qiang and Marina Kounkel and Sally Bass and Ryan Lingg and Logan Sizemore and Dylan Carroll and Brian Hutchinson and Keivan G. Stassun}, doi = {10.3847/1538-4357/adc2fc}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {49}, shortjournal = {The Astrophys. J.}, title = {A spatiotemporal data cube approach to classification of variable stars: A catalog of candidate variable stars from the TESS full-frame image raw data}, volume = {984}, year = {2025}, }
• (2025). Radial flow component of sun’s high-frequency retrograde inertial waves. ApJ, 984(1), 48. (www)

  @article{ , abstract = {Solar inertial modes have the potential to surpass the diagnostic capabilities of acoustic waves in probing the deep interior of the Sun. The fulfillment of this potential requires an accurate identification and characterization of these modes. Among the set of detected inertial modes, the equatorially antisymmetric "high-frequency retrograde" (HFR) modes has attracted special interest because numerical studies have suggested that they are not purely toroidal, as initial observations suggested, and predicted that they would possess a significant radial flow signal at depth. Here, we analyze ∼13 yr of Helioseismic and Magnetic Imager/Solar Dynamics Observatory 5° ring tiles and discover a horizontal-divergence signal, directly connected to radial flows, in the near-surface layers of the Sun. We demonstrate that this signal is indeed part of the HFR modes and not spatial leakage from prograde flows associated with magnetic regions. The amplitudes of the horizontal divergence are approximately half that associated with radial vorticity. We also report the presence of a ridge of enhanced power, although with a signal-to-noise ratio of 0.3, in the retrograde frequencies that coincides with the HFR latitudinal overtones reported by models. Using numerical linear models, we find reasonable agreement with observations, though future work on boundary considerations and the inclusion of the near-surface may improve future inferences. This is the first instance where numerical studies of solar inertial modes have guided observations, giving further confidence to past inferences that rely upon numerical models.}, archive = {J_ApJ}, author = {Chris S. Hanson and Vivek Menon and Shravan Hanasoge and Katepalli R. Sreenivasan}, doi = {10.3847/1538-4357/adc4d5}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {48}, shortjournal = {The Astrophys. J.}, title = {Radial flow component of sun’s high-frequency retrograde inertial waves}, volume = {984}, year = {2025}, }
• (2025). Fundamental understanding of magnetic reconnection via spiral CT scan. II. ion-velocity pattern and electron-velocity pattern. ApJ, 984(1), 47. (www)

  @article{ , abstract = {For the first time, we reveal the ion-velocity pattern and electron-velocity pattern around a reconnection X-line by using the spiral CT scan technique, which is a novel technique analogous to that in the hospital. This X-line was detected by the MMS spacecraft and has been widely believed to host a non-guide-field reconnection. With the help of such an advanced technique, we find two interesting features of ion velocities: (1) in the reconnection plane, ion velocities are diverged to form a "saddle-shape" pattern surrounding the X-point at scale above 0.5 d i (ion inertial length), but are stochastic near the X-point at scale below 0.5 d i ; (2) in the out-of-plane direction, ion velocities are large in the magnetosphere, but are small in the magnetosheath. Also, we successfully identify six features of electron velocities: (1) out-of-plane electron jet with scale of 0.1 d i near the X-point, (2) coupled electron and ion velocities at >0.8 d i but decoupling of them at <0.8 d i , (3) weak electron inflow and strong electron outflow at 0.1 d i < Δ < 0.8 d i , (4) stochastic electron velocities at <0.1 d i , (5) intense electron stream at 0.1 d i < Δ < 0.8 d i at the separatrix, and (6) field-aligned electron beam in the inflow region. Among these features, the first seven greatly meet theoretical expectations if we define the ion diffusion region as Δ < 0.8 d i and electron diffusion region as Δ < 0.1 d i ; the last one is a surprise, indicating that only part of the electrons participate in the reconnection process around the X-line.}, archive = {J_ApJ}, author = {H. S. Fu and Z. Wang and J. B. Cao}, doi = {10.3847/1538-4357/adc8aa}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {47}, shortjournal = {The Astrophys. J.}, title = {Fundamental understanding of magnetic reconnection via spiral CT scan. II. ion-velocity pattern and electron-velocity pattern}, volume = {984}, year = {2025}, }
• (2025). Dense cores in IRDC g14.225-0.506 revealed by ALMA observations. ApJ, 984(1), 46. (www)

  @article{ , abstract = {Dense cores in massive, parsec-scale molecular clumps are sites that harbor protocluster formation. We present results from observations toward a hub–filament structure of a massive infrared (IR) dark cloud G14.225-0.506 using the Atacama Large Millimeter/submillimeter Array. The dense cores are revealed by the 1.3 mm dust continuum emission at an angular resolution of ∼1 \mathop{.}\limits^{^{\prime\prime} } 5 and are identified through the hierarchical dendrogram technique. Combining with the N 2 D + 3–2 spectral line emission and gas temperatures derived from a previous NH 3 study, we analyze the thermodynamic properties of the dense cores. The results show transonic and supersonic-dominated turbulent motions. There is an inverse correlation between the virial parameter and the column density, which implies that denser regions may undergo stronger gravitational collapse. Molecular outflows are identified in the CO 2–1 and SiO 5–4 emission, indicating active protostellar activities in some cores. Besides these star formation signatures revealed by molecular outflows in the dense cores, previous studies in the IR, X-ray, and radio wavelengths also found a rich and widespread population of young stellar objects, showing active star formation both inside and outside of the dense cloud.}, archive = {J_ApJ}, author = {Yanhanle Zhao and Qizhou Zhang and Junhao Liu and Xing Pan and Lingzhen Zeng}, doi = {10.3847/1538-4357/adc398}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {46}, shortjournal = {The Astrophys. J.}, title = {Dense cores in IRDC g14.225-0.506 revealed by ALMA observations}, volume = {984}, year = {2025}, }
• (2025). Are multiwavelength variability events in blazars driven by a common stochastic process?. ApJ, 984(1), 45. (www)

  @article{ , abstract = {We investigate the underlying stochastic processes driving the multiwavelength variability of the blazar BL Lacertae over the past two decades. Observations from Weihai Observatory over 224 nights reveal that the power spectral slopes of intra-night variability follow a Gaussian distribution, ranging from approximately 0.4–2.6, with an average trend consistent with the long-term variability power spectrum. Using power spectral analysis methods, such as the classical periodogram and the Lomb–Scargle periodogram, in combination with modeling techniques such as the power spectral response method, the multiple fragment variance function, and the continuous time autoregressive moving average, we study the multiband power spectral characteristics across a wide range of timescales (∼7 dex). The results demonstrate that, at lower frequencies, the power spectral density across different bands shows remarkable consistency, suggesting that these variations may be driven by a common stochastic process related to the accretion disk. However, significant discrepancies arise at higher frequencies, indicating the presence of multiple stochastic processes. We propose that the variability is governed by at least two distinct processes: one related to disk stochastic processes, dominating the long-term variability, and another associated with jet stochastic processes, which may result from turbulence, particle acceleration, and shock interactions within the jet, and drive the short-term, high-frequency variations. These findings provide unique insights into the complex mechanisms underlying blazar variability and suggest an intrinsic connection between the accretion disk and jet dynamics.}, archive = {J_ApJ}, author = {Jingran Xu and Shaoming Hu and Xu Chen and Shifeng Huang}, doi = {10.3847/1538-4357/adc399}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {45}, shortjournal = {The Astrophys. J.}, title = {Are multiwavelength variability events in blazars driven by a common stochastic process?}, volume = {984}, year = {2025}, }
• (2025). A shock crashing into confined dense circumstellar matter brightens the nascent SN 2023ixf. ApJ, 984(1), 44. (www)

  @article{ , abstract = {Red supergiants may experience a short-lived period of episodic mass loss rather than steady winds before their core collapses, leading to dense circumstellar matter (CSM) close to core-collapse supernovae (SNe). Interaction of SN ejecta with such nearby CSM can generate additional radiation, appending to the cooling radiation from the shock breakout of the progenitor envelope, to brighten the nascent SN explosion. This phenomenon is conspicuous for SN 2023ixf as its V -band brightness showed a rapid increase of about three magnitudes from the first to the third day after the time of the first light, which is distinctive among type II SNe with flash ionized signatures. In this paper, we employed a Monte Carlo method to simulate the radiative diffusion process in the unshocked CSM. Considering a wide range of mass-loss rates from 10 −5 to 10 −2 M ⊙ yr −1 , we confirmed that the fast-rising light curve of SN 2023ixf can be fitted by the interaction of the SN ejecta with a CSM having a mass-loss rate of about 10 −2 M ⊙ yr −1 located within 10 15 cm of the progenitor.}, archive = {J_ApJ}, author = {Maokai Hu and Lifan Wang and Xiaofeng Wang}, doi = {10.3847/1538-4357/adc802}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {44}, shortjournal = {The Astrophys. J.}, title = {A shock crashing into confined dense circumstellar matter brightens the nascent SN 2023ixf}, volume = {984}, year = {2025}, }
• (2025). Atmospheric absorption of dark matter. ApJ, 984(1), 43. (www)

  @article{ , abstract = {Typically, the interaction between dark matter and ordinary matter is assumed to be very small. Nevertheless, in this article, I show that the effective resonant absorption of dark photon dark matter in the atmosphere is definitely possible. This might also be associated with the alleged temperature anomalies observed in our upper stratosphere. By allowing a small amount of additional energy deposition to our upper stratosphere, a narrow dark matter mass range m A ∼ 0.0001–0.001 eV and the corresponding range of the mixing parameter ε are constrained for the first time. This proposal might overturn our usual assumption of extremely weak interaction between dark matter and ordinary matter and revive the hope of detecting dark matter directly. Some important implications of this proposal, such as the heating of planets and supermassive dark stars, would also be discussed.}, archive = {J_ApJ}, author = {Man Ho Chan}, doi = {10.3847/1538-4357/adc810}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {43}, shortjournal = {The Astrophys. J.}, title = {Atmospheric absorption of dark matter}, volume = {984}, year = {2025}, }
• (2025). LAMOST j101356.33+272410.7: A detached white Dwarf–Main-sequence binary with a massive white dwarf within the period gap. ApJ, 984(1), 42. (www)

  @article{ , abstract = {We report the analysis of the detached eclipsing spectroscopic binary system LAMOST J101356.33+272410.7, which features a massive white dwarf and has an orbital period of 185.82 minutes. Using Large Sky Area Multi-Object Fiber Spectroscopic Telescope and Sloan Digital Sky Survey spectra, we determined the stellar parameters, radial velocity semiamplitudes, and orbital periods of both components. Spectral energy distribution fitting of photometric data from the Galaxy Evolution Explorer, the Two Micron All Sky Survey, and Pan-STARRS1 yielded the effective temperatures and photometric radii. Eclipsing analysis of high-speed photometric data from the Liverpool Telescope provided orbital inclination, masses, radii, and related physical parameters. The white dwarf in this system has a mass of 1.05 ± 0.09 M ⊙ and a radius of 0.0090 ± 0.0008 R ⊙ , while the main-sequence star has a mass of 0.299 ± 0.045 M ⊙ and a radius of 0.286 ± 0.018 R ⊙ . Emission lines observed in the spectra indicate the likely presence of stellar magnetic activity in this system. The relatively cool temperature of the white dwarf suggests that the system could be a post-common-envelope binary (PCEB) that has not undergone mass transfer, while the presence of a massive white dwarf indicates that the system might also represent a detached cataclysmic variable crossing the period gap. We suggest that the system is more likely to be a PCEB, and it is predicted to evolve into a cataclysmic variable and begin mass transfer in approximately 0.27 Gyr.}, archive = {J_ApJ}, author = {Yuji He and Hailong Yuan and Zhongrui Bai and Mingkuan Yang and Mengxin Wang and Yiqiao Dong and Xin Huang and Ming Zhou and Qian Liu and Xiaozhen Yang and Ganyu Li and Ziyue Jiang and Haotong Zhang}, doi = {10.3847/1538-4357/adc0fa}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {42}, shortjournal = {The Astrophys. J.}, title = {LAMOST j101356.33+272410.7: A detached white Dwarf–Main-sequence binary with a massive white dwarf within the period gap}, volume = {984}, year = {2025}, }
• (2025). A multimessenger mass determination method for LISA neutron Star–White dwarf binaries. ApJ, 984(1), 41. (www)

  @article{ , abstract = {Determining the masses of neutron stars (NSs) accurately improves our understanding of the NS interior and complicated binary evolution. However, the masses of the systems are degenerate with the orbital inclination angle when using solely gravitational waves (GWs) or electromagnetic measurements, especially for face-on binaries. Taking advantage of both GWs and optical observations for LISA NS–white dwarf (WD) binaries, we propose a mass determination method utilising multimessenger observational information. By combining the binary mass function obtained from optical observations and a GW mass function, which we introduce, derived from GW observations, we demonstrate how we can set improved constraints on the NS mass and break the degeneracy in the mass and viewing inclination determination. We further comment on the universal relation of the error bar of the GW mass function versus the GW signal-to-noise ratio and propose a simple method for estimating the capability of using GW observations for mass determination with LISA. We show that for ultracompact NS–WD binaries within our Galaxy, the mass of the NS can be constrained to within an accuracy of  ±0.2 M ⊙ with the proposed method.}, archive = {J_ApJ}, author = {Kaye Jiale Li and Jane SiNan Long and Kinwah Wu and Albert K. H. Kong}, doi = {10.3847/1538-4357/adc0fd}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {41}, shortjournal = {The Astrophys. J.}, title = {A multimessenger mass determination method for LISA neutron Star–White dwarf binaries}, volume = {984}, year = {2025}, }
• (2025). The AstroSat UV deep field south. II. a diverse set of lyman-continuum leakers at z ∼ 1. ApJ, 984(1), 40. (www)

  @article{ , abstract = {We report the detection of five newly identified Lyman-continuum (LyC) leaker candidates at redshifts 0.99–1.42 in the AstroSat UV Deep Field South F154W image. We derive physical properties of these galaxies using a combination of spectral-energy distribution fitting and information from publicly available spectra. The estimated escape fraction of these objects varies from 14% to 85% after accounting for the intergalactic medium attenuation. With only about a dozen known leakers at these redshifts, these detections significantly raise the fraction of LyC leakers in this redshift-range. High-resolution Hubble Space Telescope UV imaging reveals that a subset of the galaxies in our sample have blue star-forming structures that are likely associated with harder ionizing sources. We find tentative evidence that the LyC emission is spatially offset from the nonionizing UV-continuum centers of these galaxies. The integrated properties of these galaxies, such as the UV-continuum slope, dust attenuation, stellar mass, and [O III] λ 5007/[O II] λ 3727 ratios, make them atypical compared to known LyC leakers. The leakage of LyC photons from these systems presents a compelling challenge.}, archive = {J_ApJ}, author = {Soumil Maulick and Kanak Saha and Michael J. Rutkowski}, doi = {10.3847/1538-4357/adc10e}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {40}, shortjournal = {The Astrophys. J.}, title = {The AstroSat UV deep field south. II. a diverse set of lyman-continuum leakers at z ∼ 1}, volume = {984}, year = {2025}, }
• (2025). Dynamic motion of microwave bursts during a solar limb flare. ApJ, 984(1), 39. (www)

  @article{ , abstract = {The SOL2013-10-28T02:02:58L133C110 flare occurred on the western limb, acquiring the GOES class of X1.0, and we focus on an oscillatory phenomenon detected at 34 GHz by the Nobeyama Radioheliograph (NoRH) during this flare. The oscillation is less obvious at 17 GHz and is unseen for a hard X-ray source detected by the RHESSI. In the 94 Å images from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory, we traced the evolution of the extreme ultraviolet (EUV) images capturing an eruption around 01:58 UT over the location of the RHESSI 50–100 keV source. We located the microwave emitting loop inferred from the 17/34 GHz maps within the complex EUV loop systems, and performed a model calculation of the dynamic evolution of the microwave brightness, including the radiative transfer in a magnetically asymmetric loop and evolving nonthermal electrons. The results demonstrate that a quasiperiodic injection of energetic electrons at a fixed spatial point is sufficient to reproduce such an oscillatory motion, without an actual shift of the nonthermal electron injection point, and that the magnetic environment required for the microwave loop model is consistent with the observed EUV activities related to the overall reconnection geometry.}, archive = {J_ApJ}, author = {Sujin Kim and Jeongwoo Lee and Sung-Hong Park and Su-Chan Bong and Satoshi Masuda}, doi = {10.3847/1538-4357/adc116}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {39}, shortjournal = {The Astrophys. J.}, title = {Dynamic motion of microwave bursts during a solar limb flare}, volume = {984}, year = {2025}, }
• (2025). The temperature and first ionization potential bias of active regions and their relations to in situ solar wind. ApJ, 984(1), 38. (www)

  @article{ , abstract = {Active regions (ARs) are important sources of the slow solar wind. Connecting the properties of ARs and their associated solar wind can improve our understanding of the origin and generation mechanisms of the slow solar wind. In this study, we compare the physics properties of the AR upflow regions and nonupflow regions. The relationships between the properties of these regions and the associated solar wind parameters are analyzed. We find that the electron densities of the upflow regions are significantly lower than those of the nonupflow regions. The temperatures of the upflow regions are generally close to those of the nonupflow regions. The first ionization potential (FIP) bias varies significantly among different ARs. The FIP bias of upflow regions and that of nonupflow regions are generally similar for the same AR. The FIP bias of both upflow and nonupflow regions positively correlates with their associated solar wind. There is no relationship between the solar wind O 7+ /O 6+ and the temperature of the source regions. The results suggest that in the upflow regions, the magnetic reconnection between closed loops and open field lines may be important for generating the nascent slow solar wind. We conclude that it is unreliable to infer the temperatures of ARs directly from the O 7+ /O 6+ ratios of the in situ solar wind.}, archive = {J_ApJ}, author = {Chi Ma and Hui Fu and Maria S. Madjarska and Zhenghua Huang and Haixia Xie and Lidong Xia}, doi = {10.3847/1538-4357/adc1b8}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {38}, shortjournal = {The Astrophys. J.}, title = {The temperature and first ionization potential bias of active regions and their relations to in situ solar wind}, volume = {984}, year = {2025}, }
• (2025). Strong near-infrared emission following the long-duration GRB 211211A: Dust heating as an alternative to a kilonova. ApJ, 984(1), 37. (www)

  @article{ , abstract = {The prolonged near-infrared (NIR) emission observed following the long-duration GRB 211211A is inconsistent with afterglow emission from the shock being driven into the circumstellar medium (CSM) as well as with emission from a possible underlying supernova. It has therefore been suggested that the observed NIR flux is the signature of a kilonova—a radioactive ejecta that is similar to the outcome of the binary neutron star merger GW170817. We propose here an alternative plausible explanation. We show that the NIR flux is consistent with thermal emission from dust, heated by UV and soft-X-ray radiation produced by the interaction of the gamma-ray-burst (GRB) jet plasma with the CSM. This NIR emission was predicted by Waxman & Draine for GRBs residing near or within massive molecular clouds. The dust NIR emission scenario is consistent with a GRB at z ≲ 1. Inspection of the environment of GRB 211211A suggests that there are at least two host galaxy candidates, one at z = 0.076 and the other at z = 0.459. The z = 0.459 possibility is also consistent with the nondetection of a supernova signature in the light curve of the GRB afterglow as well as with the typical GRB gamma-ray energy for the fluence of GRB 211211A.}, archive = {J_ApJ}, author = {Eli Waxman and Eran O. Ofek and Doron Kushnir}, doi = {10.3847/1538-4357/adc1bd}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {37}, shortjournal = {The Astrophys. J.}, title = {Strong near-infrared emission following the long-duration GRB 211211A: Dust heating as an alternative to a kilonova}, volume = {984}, year = {2025}, }
• (2025). Localized heating and dynamics of the solar corona due to a symbiosis of waves and reconnection. ApJ, 984(1), 36. (www)

  @article{ , abstract = {The Sun's outer atmosphere, the corona, is maintained at mega-Kelvin temperatures and fills the heliosphere with a supersonic outflowing wind. The dissipation of magnetic waves and direct electric currents are likely to be the most significant processes for heating the corona, but a lively debate exists on their relative roles. Here, we suggest that the two are often intrinsically linked, since magnetic waves may trigger current dissipation, and impulsive reconnection can launch magnetic waves. We present a study of the first of these processes by using a 2D physics-based numerical simulation using the Adaptive Mesh Refined Versatile Advection Code. Magnetic waves such as fast magnetoacoustic waves are often observed to propagate in the large-scale corona and interact with local magnetic structures. The present numerical simulations show how the propagation of magnetic disturbances toward a null point or separator can lead to the accumulation of the electric currents. Lorentz forces can laterally push and vertically stretch the magnetic fields, forming a current sheet with a strong magnetic field gradient. The magnetic field lines then break and reconnect and so contribute toward coronal heating. Numerical results are presented that support these ideas and support the concept of a symbiosis between waves and reconnection in heating the solar corona.}, archive = {J_ApJ}, author = {A. K. Srivastava and Sripan Mondal and Eric R. Priest and Sudheer K. Mishra and David I. Pontin and R.Y. Kwon and Ding Yuan and K. Murawski and Ayumi Asai}, doi = {10.3847/1538-4357/adc379}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {36}, shortjournal = {The Astrophys. J.}, title = {Localized heating and dynamics of the solar corona due to a symbiosis of waves and reconnection}, volume = {984}, year = {2025}, }
• (2025). Limb-brightened jet in m87 from anisotropic nonthermal electrons. ApJ, 984(1), 35. (www)

  @article{ , abstract = {Very long baseline interferometry observations reveal that relativistic jets like the one in M87 have a limb-brightened, double-edged structure. Analytic and numerical models struggle to reproduce this limb-brightening. We propose a model in which we invoke anisotropy in the distribution function of synchrotron-emitting nonthermal electrons such that electron velocities are preferentially directed parallel to magnetic field lines, as suggested by recent particle-in-cell simulations of electron acceleration and the effects of synchrotron cooling. We assume that the energy injected into nonthermal electrons is proportional to the jet Poynting flux, and we account for synchrotron cooling via a broken power-law energy distribution. We implement our emission model in both general relativistic magnetohydrodynamic (GRMHD) simulations and axisymmetric force-free electrodynamic (GRFFE) jet models and produce simulated jet images at multiple scales and frequencies using polarized general relativistic radiative transfer. We find that the synchrotron emission is concentrated parallel to the local helical magnetic field and that this feature produces limb-brightened jet images on scales ranging from tens of microarcseconds to hundreds of milliarcseconds in M87. We present theoretical predictions for horizon-scale M87 jet images at 230 and 345 GHz that can be tested with next-generation instruments. Due to the scale-invariance of the GRMHD and GRFFE models, our emission prescription can be applied to other targets and serve as a foundation for a unified description of limb-brightened synchrotron images of extragalactic jets.}, archive = {J_ApJ}, author = {Yuh Tsunetoe and Dominic W. Pesce and Ramesh Narayan and Andrew Chael and Zachary Gelles and Charles Gammie and Eliot Quataert and Daniel Palumbo}, doi = {10.3847/1538-4357/adc37a}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {35}, shortjournal = {The Astrophys. J.}, title = {Limb-brightened jet in m87 from anisotropic nonthermal electrons}, volume = {984}, year = {2025}, }
• (2025). Using nebular near-infrared spectroscopy to measure asymmetric chemical distributions in 2003fg-like thermonuclear supernovae. ApJ, 984(1), 34. (www)

  @article{ , abstract = {We present an analysis of three near-infrared (NIR; 1.0–2.4 μ m) spectra of the SN 2003fg–like/"super-Chandrasekhar" Type Ia supernovae (SNe Ia) SN 2009dc, SN 2020hvf, and SN 2022pul at respective phases of +372, +296, and +294 days relative to the epoch of B -band maximum. We find that all objects in our sample have asymmetric, or "tilted," [Fe ii ] 1.257 and 1.644 μ m profiles. We quantify the asymmetry of these features using five methods: velocity at peak flux, profile tilts, residual testing, velocity fitting, and comparison to deflagration–detonation transition models. Our results demonstrate that, while the profiles of the [Fe ii ] 1.257 and 1.644 μ m features are widely varied between 2003fg-likes, these features are correlated in shape within the same SNe. This implies that line blending is most likely not the dominant cause of the asymmetries inferred from these profiles. Instead, it is more plausible that 2003fg-like SNe have aspherical chemical distributions in their inner regions. These distributions may come from aspherical progenitor systems, such as double white dwarf mergers, or off-center delayed-detonation explosions of near-Chandrasekhar mass carbon–oxygen white dwarfs. Additional late-phase NIR observation of 2003fg-like SNe and detailed 3D non-LTE modeling of these two explosion scenarios are encouraged.}, archive = {J_ApJ}, author = {J. O’Hora and C. Ashall and M. Shahbandeh and E. Hsiao and P. Hoeflich and M. D. Stritzinger and L. Galbany and E. Baron and J. DerKacy and S. Kumar and J. Lu and K. Medler and B. Shappee}, doi = {10.3847/1538-4357/adc37c}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {34}, shortjournal = {The Astrophys. J.}, title = {Using nebular near-infrared spectroscopy to measure asymmetric chemical distributions in 2003fg-like thermonuclear supernovae}, volume = {984}, year = {2025}, }
• (2025). Search for fast radio bursts and radio pulsars from pulsing ultraluminous X-ray sources. ApJ, 984(1), 33. (www)

  @article{ , abstract = {We conducted targeted fast radio burst (FRB) and pulsar searches on eight pulsing ultraluminous X-ray sources (PULXs) using the Five-hundred-meter Aperture Spherical radio Telescope (FAST) and the Parkes 64 m Radio Telescope (Murriyang) to investigate whether PULXs could be progenitors of FRBs. FAST carried out 12 observations of four PULXs, totaling 8 hr, while Parkes conducted 12 observations of the remaining four PULXs, totaling 11 hr. No significant signals were detected through single-pulse and periodic searches, covering a dispersion measure range of 0–5000 pc cm −3 , placing stringent upper limits on the radio flux density from these sources. The results imply that accretion processes and dense stellar winds in PULXs likely suppress or attenuate potential coherent emission in the radio band. Additionally, the beaming factor and luminosity of FRBs associated with PULXs, as well as the highly relativistic and magnetized nature of their outflows, may limit detectability. Nondetection yielded from the observations covering the full orbital phases of PULXs can also constrain the theoretical models that link FRB emission to highly magnetized neutron stars in binary systems.}, archive = {J_ApJ}, author = {Juntao Bai and Na Wang and Rui Luo and Wei-Yang Wang and Shi Dai and Songbo Zhang and Shiqian Zhao and Shuangqiang Wang}, doi = {10.3847/1538-4357/adc92e}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {33}, shortjournal = {The Astrophys. J.}, title = {Search for fast radio bursts and radio pulsars from pulsing ultraluminous X-ray sources}, volume = {984}, year = {2025}, }
• (2025). Quantifying feedback from narrow line region outflows in nearby active galaxies. v. the expanded sample. ApJ, 984(1), 32. (www)

  @article{ , abstract = {We present spatially resolved measurements of the ionized gas masses and mass outflow rates for six low-redshift ( z ≤ 0.02) active galaxies. In this study, we expand our sample to galaxies with more complex gas kinematics modeled as outflows along a galactic disk that is ionized by the active galactic nucleus (AGN) bicone. We use Hubble Space Telescope Space Telescope Imaging Spectrograph spectroscopy, Wide Field Camera 3 narrow-band imaging, and the photoionization modeling technique that we developed in M. Revalski et al. (Paper IV in this series) to calculate ionized gas masses using the [O iii ]/H β ratios at each radius. We combine these with existing kinematic models to derive mass and energy outflow rates, which exhibit substantial radial variations due to changes in the outflow velocities. The full sample of 12 galaxies from this series of studies spans 10 3 in bolometric luminosity, and we find that the outflows contain ionized gas masses of M ≈ 10 4.6 –10 7.2 M ⊙ , reach maximum mass outflow rates of {\dot{M}}_{out}\approx 0.1-13 M ⊙ yr −1 , and encompass kinetic energies of E ≈ 10 52 –10 56 erg. These energetic properties positively correlate with AGN luminosity. The outflow energetics are less than benchmarks for effective feedback from theoretical models, but the evacuation of gas and injection of energy may still generate long-term effects on star formation in these nearby galaxies. These results highlight the necessity of high spatial resolution imaging and spectroscopy for accurately modeling ionized outflows in active galaxies.}, archive = {J_ApJ}, author = {Mitchell Revalski and D. Michael Crenshaw and Garrett E. Polack and Marc Rafelski and Steven B. Kraemer and Travis C. Fischer and Beena Meena and Henrique R. Schmitt and Anna Trindade Falcão and Julia Falcone and Maura Kathleen Shea}, doi = {10.3847/1538-4357/adc131}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {32}, shortjournal = {The Astrophys. J.}, title = {Quantifying feedback from narrow line region outflows in nearby active galaxies. v. the expanded sample}, volume = {984}, year = {2025}, }
• (2025). NICER spectral and timing analysis of 4U 1630-47 and its heartbeat state. ApJ, 984(1), 31. (www)

  @article{ , abstract = {We present a spectral and timing analysis of NICER observations of the black hole X-ray binary 4U 1630-47 from 2018 to 2024. We find relativistic reflection features in the hard and soft intermediate states, and disk wind absorption features in the soft intermediate state and soft state. We fit the reflection features with relxillCP and find a stable and untruncated disk in the intermediate states; we fit the wind features with XSTAR and find a stable, highly ionized wind with high column density across different outbursts. Specifically, the heartbeat state is seen in two observations in 2021 and 2023, respectively. Through the phase-resolved spectral fitting, we find the flux of the source to be correlated with the disk parameters while no strong correlation with the coronal parameters is observed, consistent with the scenario given by the inner disk radiation pressure instability. A hard lag on a timescale of 1 s and high coherence are observed near the characteristic frequency of the heartbeat, which can be explained by the viscous propagation of mass accretion fluctuations in the disk. The positive relationship between the heartbeat fractional rms and energy can possibly be explained by a disk-originated oscillation that is then magnified by the coronal scattering.}, archive = {J_ApJ}, author = {Ningyue Fan and James F. Steiner and Cosimo Bambi and Erin Kara and Yuexin Zhang and Ole König}, doi = {10.3847/1538-4357/adc25a}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {31}, shortjournal = {The Astrophys. J.}, title = {NICER spectral and timing analysis of 4U 1630-47 and its heartbeat state}, volume = {984}, year = {2025}, }
• (2025). Correlations between the neutron star Mass–Radius relation and the equation of state of dense matter. ApJ, 984(1), 30. (www)

  @article{ , abstract = {We develop an analytic method of inverting the Tolman–Oppenheimer–Volkoff relations to high accuracy. In principle, a specified energy density–pressure relation gives a unique mass–radius ( M – R ) relation and vice versa. Our method is developed from the strong correlations that are shown to exist between the neutron star mass–radius curve and the equation of state (EOS) or pressure–energy density relation. Selecting points that have masses equal to fixed fractions of the maximum mass, we find a semi-universal power-law relation between the central energy densities, pressures, sound speeds, chemical potentials, and number densities of those stars, with the maximum mass and the radii of one or more fractional maximum mass points. Rms fitting accuracies, for EOSs without large first-order phase transitions, are typically 0.5% for all quantities at all mass points. The method also works well, although less accurately, in reconstructing the EOS of hybrid stars with first-order phase transitions. These results permit, in effect, an analytic method of inverting an arbitrary M – R curve to yield its underlying EOS. We discuss applications of this inversion technique to the inference of the dense matter EOS from measurements of neutron star masses and radii as a possible alternative to traditional Bayesian approaches.}, archive = {J_ApJ}, author = {Boyang Sun and James M. Lattimer}, doi = {10.3847/1538-4357/adc25d}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {30}, shortjournal = {The Astrophys. J.}, title = {Correlations between the neutron star Mass–Radius relation and the equation of state of dense matter}, volume = {984}, year = {2025}, }
• (2025). Characterizing magnetic properties of young protostars in orion. ApJ, 984(1), 29. (www)

  @article{ , abstract = {The B -field Orion Protostellar Survey (BOPS) recently obtained polarimetric observations at 870 μ m toward 61 protostars in the Orion molecular clouds with ∼1'' spatial resolution using the Atacama Large Millimeter/submillimeter Array. From the BOPS sample, we selected the 26 protostars with extended polarized emission within a radius of ∼6'' (2400 au) around the protostar. This allows us to have sufficient statistical polarization data to infer the magnetic field strength. The magnetic field strength is derived using the Davis–Chandrasekhar–Fermi method. The underlying magnetic field strengths are approximately 2.0 mG for protostars with a standard hourglass magnetic field morphology, which is higher than the values derived for protostars with rotated hourglass, spiral, and complex magnetic field configurations (≲1.0 mG). This suggests that the magnetic field plays a more significant role in envelopes exhibiting a standard hourglass field morphology, and a value of ≳2.0 mG would be required to maintain such a structure at these scales. Furthermore, most protostars in the sample are slightly supercritical, with mass-to-flux ratios ≲3.0. In particular, the mass-to-flux ratios for all protostars with a standard hourglass magnetic field morphology are lower than 3.0. However, these ratios do not account for the contribution of the protostellar mass, which means they are likely significantly underestimated.}, archive = {J_ApJ}, author = {Bo Huang and Josep M. Girart and Ian W. Stephens and Philip C. Myers and Qizhou Zhang and Paulo Cortes and Álvaro Sánchez-Monge and Manuel Fernández López and Valentin J. M. Le Gouellec and Tom Megeath and Nadia M. Murillo and John M. Carpenter and Zhi-Yun Li and Junhao Liu and Leslie W. Looney and Sarah Sadavoy and Nicole Karnath and Woojin Kwon}, doi = {10.3847/1538-4357/adc30b}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {29}, shortjournal = {The Astrophys. J.}, title = {Characterizing magnetic properties of young protostars in orion}, volume = {984}, year = {2025}, }
• (2025). Kinetic simulations of the Kruskal–Schwarzschild instability in accelerating striped outflows: Dynamics and energy dissipation. ApJ, 984(1), 28. (www)

  @article{ , abstract = {Astrophysical relativistic outflows are launched as Poynting-flux dominated, yet the mechanism governing efficient magnetic dissipation, which powers the observed emission, is still poorly understood. We study magnetic energy dissipation in relativistic "striped" jets, which host current sheets separating magnetically dominated regions with opposite field polarity. The effective gravity force g in the rest frame of accelerating jets drives the Kruskal–Schwarzschild instability (KSI), a magnetic analog of the Rayleigh–Taylor instability. By means of 2D and 3D particle-in-cell simulations, we study the linear and nonlinear evolution of the KSI. The linear stage is well described by linear stability analysis. The nonlinear stages of the KSI generate thin (skin-depth-thick) current layers, with length comparable to the dominant KSI wavelength. There, the relativistic drift-kink mode and the tearing mode drive efficient magnetic dissipation. The dissipation rate can be cast as an increase in the effective width Δ eff of the dissipative region, which follows d{{\rm{\Delta }}}_{{\rm{eff}}}/dt\simeq 0.05\sqrt{{{\rm{\Delta }}}_{{\rm{eff}}}\,g} . Our results have important implications for the location of the dissipation region in gamma-ray burst and active galactic nuclei jets.}, archive = {J_ApJ}, author = {William Groger and Hayk Hakobyan and Lorenzo Sironi}, doi = {10.3847/1538-4357/adc446}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {28}, shortjournal = {The Astrophys. J.}, title = {Kinetic simulations of the Kruskal–Schwarzschild instability in accelerating striped outflows: Dynamics and energy dissipation}, volume = {984}, year = {2025}, }
• (2025). Inferring jet physics from neutron Star–Black hole mergers with gravitational waves. ApJ, 984(1), 27. (www)

  @article{ , abstract = {Neutron star–black hole (NSBH) mergers that undergo tidal disruption may launch jets that could power a gamma-ray burst (GRB). We use a population of simulated NSBH systems to measure jet parameters from the gravitational waves emitted by these systems. The conditions during the tidal disruption and merger phase required to power a GRB are uncertain. It is likely that the system must achieve some minimum remnant baryonic mass after the merger before a jet can be launched to power a GRB. Assuming a fiducial neutron star equation of state, we show how Bayesian hierarchical inference can be used to infer the minimum remnant mass required to launch a GRB jet as well as features of the opening angle distribution of the GRB jets. We find that with 200 NSBH observations, we can measure the minimum disk mass to within 0.01 M ⊙ at 90% credibility. We simultaneously infer the GRB opening angle to within 13° at 90% credibility. We conclude that upcoming upgrades to the LIGO observatories may provide important new insights into the physics of NSBH jets.}, archive = {J_ApJ}, author = {Teagan A. Clarke and Paul D. Lasky and Eric Thrane}, doi = {10.3847/1538-4357/adc804}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {27}, shortjournal = {The Astrophys. J.}, title = {Inferring jet physics from neutron Star–Black hole mergers with gravitational waves}, volume = {984}, year = {2025}, }
• (2025). PSZ2 g181.06+48.47. III. weak-lensing analysis and merging scenario reconstruction of a low-mass cluster with exceptionally distant radio relics. ApJ, 984(1), 26. (www)

  @article{ , abstract = {The galaxy cluster PSZ2 G181.06+48.47 ( z = 0.234) is a post-merging system that exhibits symmetric double radio relics separated by ∼2.7 Mpc. We present the first weak-lensing analysis of PSZ2 G181.06+48.47 and propose possible merging scenarios using numerical simulations. Our analysis with Subaru Hyper Suprime-Cam imaging identifies a binary dark matter (DM) structure consisting of northern and southern components, separated by ∼500 kpc. Assuming Navarro–Frenk–White (NFW) halos, the masses for the northern and southern subclusters are {M}_{200c}^{\,\rm{N}\,}=0.8{8}_{-0.30}^{+0.35}\times 1{0}^{14}{M}_{\odot } and {M}_{200c}^{\,\rm{S}\,}=2.7{1}_{-0.48}^{+0.51}\times 1{0}^{14}{M}_{\odot } , respectively. By superposing the two NFW halos, we determine the total mass of the cluster to be {M}_{200c}=4.2{2}_{-1.00}^{+1.10}\times 1{0}^{14}{M}_{\odot } ( {M}_{500c}=2.9{0}_{-0.69}^{+0.75}\times 1{0}^{14}{M}_{\odot } ). Our mass estimate suggests that the two relics are located around the cluster R 200 c , where the density of the intracluster medium is very low. Our idealized simulations find that an off-axis collision of a 3:1 major merger can simultaneously reproduce the observed relic and DM halo separations. From these findings, we suggest that the system is observed ∼0.9 Gyr after the first pericenter passage and is returning from the first apocenter.}, archive = {J_ApJ}, author = {Eunmo Ahn and Hyejeon Cho and M. James Jee and Wonki Lee and Andra Stroe and Kamlesh Rajpurohit and Kyle Finner and William Forman and Christine Jones and Reinout van Weeren}, doi = {10.3847/1538-4357/adbc99}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {26}, shortjournal = {The Astrophys. J.}, title = {PSZ2 g181.06+48.47. III. weak-lensing analysis and merging scenario reconstruction of a low-mass cluster with exceptionally distant radio relics}, volume = {984}, year = {2025}, }
• (2025). PSZ2 g181.06+48.47. II. radio analysis of a low-mass cluster with exceptionally distant radio relics. ApJ, 984(1), 25. (www)

  @article{ , abstract = {We report upgraded Giant Metrewave Radio Telescope and Karl J. Jansky Very Large Array radio observations of a low-mass merging galaxy cluster PSZ2 G181.06+48.47. This exceptional galaxy cluster hosts two megaparsec-scale diffuse sources, symmetrically located with respect to the cluster center and separated by about 2.6 Mpc in projection. We detect these low surface brightness sources in our new high-frequency observations (0.3–2 GHz) and classify them as radio relics associated with merger-driven shock fronts. The southwest relic exhibits an inverted morphology and shows evidence of spectral steepening in the post-shock region, potentially tracing a high Mach number shock (∼4) under the framework of diffusive shock acceleration. The northeast relic is found to be highly polarized with a 22% average polarization fraction at 1.5 GHz and aligned magnetic field vectors. Its spectral and polarization properties, along with the presence of a nearby tailed galaxy, support reacceleration scenarios. The merger axis defined by the two relics is tilted by ∼45° with respect to the plane of the sky, which implies an unprecedented physical separation of ∼3.5 Mpc. We also detect a possible faint radio halo, suggesting weak turbulence in the central cluster region. We conclude that the faint double relics can be best explained by two outward-moving shock waves in which particles are (re)accelerated and that the cluster is in an evolved merger state. PSZ2 G181.06+48.47 presents a unique opportunity to investigate particle acceleration in low-mass systems characterized by large relic separations.}, archive = {J_ApJ}, author = {Kamlesh Rajpurohit and Andra Stroe and Ewan O’Sullivan and Eunmo Ahn and Wonki Lee and Hyejeon Cho and M. James Jee and Reinout van Weeren and Lorenzo Lovisari and Kyle Finner and Aurora Simionescu and William Forman and Timothy Shimwell and Christine Jones and Zhenlin Zhu and Scott Randall}, doi = {10.3847/1538-4357/adbbb9}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {25}, shortjournal = {The Astrophys. J.}, title = {PSZ2 g181.06+48.47. II. radio analysis of a low-mass cluster with exceptionally distant radio relics}, volume = {984}, year = {2025}, }
• (2025). PSZ2 g181.06+48.47. i. X-ray exploration of a low-mass cluster with exceptionally distant radio relics. ApJ, 984(1), 24. (www)

  @article{ , abstract = {Relics are diffuse, highly polarized radio sources that trace merger-driven shocks at the periphery of merging galaxy clusters. The Low Frequency Array survey recently discovered a rare example of double relics in the low-mass cluster PSZ2 G181.06+48.47. Through a detailed exploration of new Chandra and XMM-Newton observations, we reveal that PSZ2 G181.06+48.47 has a lower mass ( {M}_{\mathrm{500,X}}=2.3{2}_{-0.25}^{+0.29}\times 1{0}^{14}\ {M}_{\odot } ) than previously thought. Despite its cool global temperature of k{T}_{500}=3.6{2}_{-0.07}^{+0.15} keV, PSZ2 G181.06+48.47 is one of the most disturbed clusters in the Planck sample, with a complex morphological and thermodynamic structure. We discover a set of three discontinuities within <500 kpc of the cluster center, and, from a surface brightness analysis, place 5 σ upper limits of {{ \mathcal M }}_{\mathrm{NE}}\lt 1.43 and {{ \mathcal M }}_{\mathrm{SW}}\lt 1.57 for any shock associated with the relic locations. We also revise established scaling relations for double radio relics by adding 12 new systems not included in previous work. The PSZ2 G181.06+48.47 relics have the widest separation (scaled for r 500 ) of all known double relic systems. The exceptional distance from the cluster center (> r 200 ) indicates the relics may be associated with shocks in the "runaway" phase. We propose that this late-stage, post-apocenter merger is captured as the two subclusters with a mass ratio of 1.2–1.4 fall back into each other. The outer relic shocks were likely produced at the first core passage, while the inner discontinuities are associated with the second infall.}, archive = {J_ApJ}, author = {Andra Stroe and Kamlesh Rajpurohit and Zhenlin Zhu and Lorenzo Lovisari and Aurora Simionescu and Ewan O’Sullivan and Scott Randall and William Forman and Hiroki Akamatsu and Reinout van Weeren and M. James Jee and Wonki Lee and Hyejeon Cho and Eunmo Ahn and Kyle Finner and Christine Jones}, doi = {10.3847/1538-4357/adb731}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {24}, shortjournal = {The Astrophys. J.}, title = {PSZ2 g181.06+48.47. i. X-ray exploration of a low-mass cluster with exceptionally distant radio relics}, volume = {984}, year = {2025}, }
• (2025). Near-infrared spectral properties of type Ib/Ic supernova progenitors and implications for JWST and NGRST observations. ApJ, 984(1), 23. (www)

  @article{ , abstract = {While about 20 type II supernova (SN II) progenitors have been identified using optical data from the Hubble Space Telescope (HST), direct detection of type Ib/Ic supernova (SN Ib/Ic) progenitors remains challenging, due to their faint optical brightness and highly obscured environments. This study aims to investigate the detection limits and advantages of near-infrared (near-IR) observations with the James Webb Space Telescope (JWST) and the Nancy Grace Roman Space Telescope (NGRST) for the detection of SN Ib/Ic progenitors. The spectral energy distributions of SN Ib/Ic progenitor models with various masses, chemical compositions, and mass-loss rates are calculated with the non-LTE radiative transfer code CMFGEN. We then assess the detectability of SN Ib/Ic progenitors using near-IR filters from JWST and NGRST, comparing the results to the capabilities of HST. Our analysis indicates that near-IR observations significantly outperform HST in detecting SN Ib/Ic progenitors when considering the effect of extinction. Near-IR magnitudes also provide better constraints on the mass-loss rates of progenitors, because of the free–free emission from the wind matter. Additionally, near-IR magnitudes and color–color diagrams are effective in distinguishing SN Ib/Ic progenitors from possible companion and/or background objects. This study suggests that JWST and NGRST can play a crucial role in advancing our understanding of SN Ib/Ic progenitors, by improving detectability and offering better constraints on progenitor properties. We emphasize that observations with exposure times exceeding 1 hr would be needed to detect typical SNe Ib/Ic progenitors at distances greater than 10 Mpc.}, archive = {J_ApJ}, author = {Moo-Keon Jung and Sung-Chul Yoon}, doi = {10.3847/1538-4357/adc09e}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {23}, shortjournal = {The Astrophys. J.}, title = {Near-infrared spectral properties of type Ib/Ic supernova progenitors and implications for JWST and NGRST observations}, volume = {984}, year = {2025}, }
• (2025). Velocity structure correlations between the nebular, molecular, and atmospheric gases in the cores of four cool core clusters. ApJ, 984(1), 22. (www)

  @article{ , abstract = {We investigate the velocity structure of nebular gas in the central galaxies of four clusters: A1835, PKS 0745−191, A262, and RXJ0820.9+0752, using data from the Keck Cosmic Web Imager. Velocity structure functions (VSFs) of the [O ii ] emission line are compared to VSFs of molecular clouds observed with the Atacama Large Millimeter/submillimeter Array. Apart from A262, where the gas is located in a circumnuclear disk, the nebular gas in the remaining galaxies lies in off-nuclear filamentary structures with VSFs steeper than the Kolmogorov slope. This steepening may be plausibly attributed to gravity, although other factors, such as magnetic stresses and bulk motion, may be significant. The VSFs of CO and [O ii ] emission are similar in RXJ0820 and A262, indicating close coupling of the nebular and molecular gases. In contrast, the nebular and molecular gases are differentiated on most scales in PKS 0745 and A1835. This discrepancy is likely due to the radioactive galactic nucleus churning the gas. We compare the scale-dependent velocity amplitudes of the hot atmospheres constrained by X-ray surface brightness fluctuation analysis using Chandra observations to the nebular VSFs. The large-scale consistency in A1835 and RXJ0820 is consistent with condensation from the hot atmospheres. We explore substantial systematic biases, including projection effects, windowing, and smoothing effects, when comparing VSFs using different telescopes and instruments.}, archive = {J_ApJ}, author = {Muzi Li and B.R. McNamara and Alison L. Coil and Marie-Joëlle Gingras and Fabrizio Brighenti and H.R. Russell and Prathamesh D. Tamhaneh and S. Peng Oh and Serena Perrotta}, doi = {10.3847/1538-4357/adc102}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {22}, shortjournal = {The Astrophys. J.}, title = {Velocity structure correlations between the nebular, molecular, and atmospheric gases in the cores of four cool core clusters}, volume = {984}, year = {2025}, }
• (2025). Spatially-resolved TRGB JWST Color–Magnitude diagram as a tool to measure fossil stellar metallicity gradients in disk galaxies: NGC 628. ApJ, 984(1), 21. (www)

  @article{ , abstract = {We use archival JWST/NIRCam images in the F115W, F150W, and F200W filters to measure the tip of the red giant branch (TRGB) magnitudes across the disk of the late-type spiral galaxy NGC 628. In this exploratory study, we demonstrate how the metallicity-dependence of TRGB magnitudes in the near-infrared (NIR) filters can be exploited by making use of the theoretical isochrones to determine metallicities of the fossil 10 Gyr old population over kiloparsec scales without being affected by the age–metallicity reddening degeneracy. We obtain a smooth metallicity gradient that decreases from Z = 0.003 in the central regions to Z = 0.002 in the external parts, with a typical error on Z of 0.0002. The extinction variation across the disk caused by the diffuse interstellar dust is spiky with a median value of A V = 0.12 mag. We propose that the large bubbles in the disks of galaxies offer dust-free lines of sight for measuring the TRGB magnitudes, and hence the distance to galaxies, to an accuracy that is as good as that of the halo populations. Using the Phantom Void, we obtain a TRGB distance modulus of 29.81 ± 0.05(stat) ± 0.06(sys) mag for NGC 628, which agrees well with the most recent PNLF measurement of 29.89 {}_{-0.09}^{+0.06} for this galaxy.}, archive = {J_ApJ}, author = {Avinash Ck and Divakara Mayya and Alessandro Bressan and Jairo Andres Alzate Trujillo}, doi = {10.3847/1538-4357/adc105}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {21}, shortjournal = {The Astrophys. J.}, title = {Spatially-resolved TRGB JWST Color–Magnitude diagram as a tool to measure fossil stellar metallicity gradients in disk galaxies: NGC 628}, volume = {984}, year = {2025}, }
• (2025). Warm ionized gas outflows in active galactic nuclei: What causes them?. ApJ, 984(1), 20. (www)

  @article{ , abstract = {The driving force behind outflows, often invoked to understand the correlation between the supermassive black holes powering active galactic nuclei (AGN) and their host galaxy properties, remains uncertain. We provide new insights into the mechanisms that trigger warm ionized outflows in AGN, based on findings from the MaNGA survey. Our sample comprises 538 AGN with strong [O iii ] λ 5007 emission lines, of which 197 are detected in radio and 341 are radio-undetected. We analyzed the [O iii ] λ 5007 line in summed spectra, extracted over their central 500 × 500 pc 2 region. The calculated Balmer 4000 Å break, D n 4000, is larger than 1.45 for ∼95% of the sources, indicating that the specific star formation rate in their central regions is less than 10 −11.5 yr −1 , which points to evidence of negative AGN feedback suppressing star formation. Considering the whole sample, radio-detected sources show a greater outflow detection rate (56% ± 7%) than radio-undetected sources (25% ± 3%). They also show higher velocity, mass outflow rate, outflow power, and outflow momentum rate. We noticed a strong correlation between outflow characteristics and bolometric luminosity in both samples, except that the correlation is steeper for the radio-detected sample. Our findings suggest that (a) warm ionized outflows are prevalent in all types of AGN, (b) radiation from AGN is the primary driver of these outflows, (c) radio jets are likely to play a secondary role in enhancing the gas kinematics over and above that caused by radiation, and (d) there is very little star formation in the central regions of the galaxies, possibly due to negative feedback from AGN activity.}, archive = {J_ApJ}, author = {Payel Nandi and C. S. Stalin and D. J. Saikia}, doi = {10.3847/1538-4357/adc110}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {20}, shortjournal = {The Astrophys. J.}, title = {Warm ionized gas outflows in active galactic nuclei: What causes them?}, volume = {984}, year = {2025}, }
• (2025). Continuum reverberation in active galactic nuclei disks only with sufficient X-ray luminosity and low albedo. ApJ, 984(1), 19. (www)

  @article{ , abstract = {Disk continuum reverberation mapping is one of the primary ways we learn about active galactic nuclei (AGN) accretion disks. Reverberation mapping assumes that time-varying X-rays incident on the accretion disk drive variability in UV–optical light curves emitted by AGN disks and uses lags between X-ray and UV–optical variability on the light-crossing timescale to measure the radial temperature profile and extent of AGN disks. However, recent reverberation mapping campaigns have revealed oddities in some sources, such as weakly correlated X-ray and UV light curves, longer than anticipated lags, and evidence of intrinsic variability from disk fluctuations. To understand how X-ray reverberation works with realistic accretion disk structures, we perform 3D multifrequency radiation magnetohydrodynamic simulations of X-ray reprocessing by the UV-emitting region of an AGN disk using sophisticated opacity models that include line opacities for both the X-ray and UV radiation. We find there are two important factors that determine whether X-ray irradiation and UV emission will be well-correlated: the ratio of X-ray to UV luminosity and significant absorption. When these factors are met, the reprocessing of X-rays into UV is nearly instantaneous, as is often assumed, although linear reprocessing models are insufficient to fully capture X-ray reprocessing in our simulations. Nevertheless, we can still easily recover mock lags in our light curves using software that assumes linear reprocessing. Finally, the X-rays in our simulation heat the disk, increasing temperatures by a factor of 2–5 in the optically thin region, which could help explain the discrepancy between measured and anticipated lags.}, archive = {J_ApJ}, author = {Amy Secunda and Yan-Fei Jiang and Jenny E. Greene}, doi = {10.3847/1538-4357/adc25b}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {19}, shortjournal = {The Astrophys. J.}, title = {Continuum reverberation in active galactic nuclei disks only with sufficient X-ray luminosity and low albedo}, volume = {984}, year = {2025}, }
• (2025). The initial mass function of the galactic early-type field stars based on the LAMOST survey. ApJ, 984(1), 18. (www)

  @article{ , abstract = {Research on the high-mass end of the initial mass function (IMF) has been limited due to a scarcity of samples. Recently, Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST), as the most efficient spectroscopic telescope, has provided new opportunities for related research. In this study, based on approximately 70,000 main-sequence early-type stars from the LAMOST survey, we investigated the IMF of Galactic field stars at the high-mass end (1.5 ≤ M / M ⊙ ≤ 7.1). First, we derived the slope of the present-day mass function (PDMF), finding {\alpha }_{{\rm{pre}}}=5.59\pm 0.02 after correcting for selection effect in the observed sample. We then accounted for the effects of stellar evolution and unresolved binaries to correct the PDMF back to the IMF, resulting in α ini = 2.70 ∼ 2.82. Notably, we corrected both stellar evolution and unresolved binary effects simultaneously by using binary-Star evolution code, which enhances the robustness of our results. Additionally, we investigated how different mass-ratio ( q ) distributions of binaries and different star formation histories of the Milky Way impact the IMF. Finally, we tested samples across different spatial scales and found that α ini may exhibit a decreasing trend as the spatial scale increases, which could be attributed to variations in metallicity.}, archive = {J_ApJ}, author = {Qida Li and Jianping Xiong and Zhenwei Li and Dan Qiu and Chao Liu and Zhanwen Han and Xuefei Chen}, doi = {10.3847/1538-4357/adc309}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {18}, shortjournal = {The Astrophys. J.}, title = {The initial mass function of the galactic early-type field stars based on the LAMOST survey}, volume = {984}, year = {2025}, }
• (2025). A large systematic search for close supermassive binary and rapidly recoiling black holes. IV. ultraviolet spectroscopy*†. ApJ, 984(1), 17. (www)

  @article{ , abstract = {We present Hubble Space Telescope ultraviolet (UV) spectroscopy of 13 quasars at z < 0.7, along with contemporaneous optical spectra from ground-based telescopes. The targets were selected to have broad H β emission lines with substantial velocity offsets relative to the rest frame of their host galaxy. By analogy to single-line spectroscopic binary stars, these objects have been regarded as supermassive black hole binary (SBHB) candidates where the offset emission lines may be caused by bulk orbital motion. The best alternative explanation is that the H β line profile is the result of nonaxisymmetric emission from a disk-like broad-line region associated with a single supermassive black hole. We use the broad UV line profiles to discriminate between these two scenarios. We describe our methodology for isolating the broad optical and UV line profiles and the criteria we apply for comparing them. Of the 13 SBHB candidates, three have strong evidence in support of the SBHB hypothesis, five have tentative support, one is disfavored, and four have such severely absorbed UV line profiles that the results are inconclusive.}, archive = {J_ApJ}, author = {Jessie C. Runnoe and Michael Eracleous and Tamara Bogdanović and Jules P. Halpern and Steinn Sigurđsson}, doi = {10.3847/1538-4357/adba58}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {17}, shortjournal = {The Astrophys. J.}, title = {A large systematic search for close supermassive binary and rapidly recoiling black holes. IV. ultraviolet spectroscopy*†}, volume = {984}, year = {2025}, }
• (2025). R-JET: A postprocessing code for radiative transport in relativistic jets. ApJ, 984(1), 16. (www)

  @article{ , abstract = {We describe a postprocessing radiative transport code for computing the spectra, the core shift, and the surface-brightness distribution of special relativistic jets with arbitrary optical thickness. The jet consists of an electron–positron pair plasma and an electron–proton normal plasma. Electrons and positrons are relativistic and composed of thermal and nonthermal components, while protons are nonrelativistic and nonradiating. The fraction of a pair plasma, as well as the fraction of a nonthermal component, can be arbitrarily chosen. Only the synchrotron process is considered for emission and absorption when the radiative-transfer equation is integrated along our lines of sight. We describe a suite of test problems and confirm the frequency dependence of the core shift in the Konigl jet model when the plasma is composed of nonthermal components alone. Finally, we illustrate the capabilities of the code with model calculations, demonstrating that the jet will exhibit a limb-brightened structure in general when it is energized by the rotational energy of the black hole. It is also demonstrated that such limb-brightened jets show a ring-like structure in the brightness map when we observe the jet launching region nearly face-on.}, archive = {J_ApJ}, author = {Kouichi Hirotani and Hsien Shang and Ruben Krasnopolsky and Kenichi Nishikawa}, doi = {10.3847/1538-4357/adbaf2}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {16}, shortjournal = {The Astrophys. J.}, title = {R-JET: A postprocessing code for radiative transport in relativistic jets}, volume = {984}, year = {2025}, }
• (2025). FEASTS combined with interferometry. IV. mapping h i emission to a limit of NH i = 1017.7 cm−2 in seven edge-on galaxies. ApJ, 984(1), 15. (www)

  @article{ , abstract = {We present a statistical study of the neutral atomic hydrogen (H i ) gas extending into the circumgalactic medium perpendicular to the disk for seven edge-on galaxies with inclinations above 85° from the FEASTS program with a 3 σ (20 km s −1 ) column density ( N H i ) depth of 5 × 10 17 cm −2 . We develop two photometric methods to separate the extraplanar H i from the disk component based on existing interferometric data and parametric modeling of the disk flux distribution, respectively. With both methods, the FEASTS data exhibit clear extended wings beyond the disk along the minor axis. The extraplanar H i accounts for 5%–20% of the total H i mass and extends to 20–50 kpc at N H i = 10 18 cm −2 . We find a tight positive correlation between vertical extensions of the extraplanar H i and total H i mass M H i . The isodensity shape of H i at N H i = 10 18 cm −2 has an average axis ratio of 0.56 ± 0.11. The off-disk N H i profiles of these edge-on galaxies well represent the lower envelope of previous Ly α absorption measurements at low redshift. Our results suggest that at N H i = 5 × 10 17 cm −2 , the H i extends considerably further than the known thin and thick disks in the vertical direction but still remains much flatter than a spherical distribution, consistent with theoretical expectations that outflow, circulation, and accretion should have different impacts in these two directions. We show the tension of our results with Illustris and TNG predictions, highlighting the constraining power of our results for future simulations.}, archive = {J_ApJ}, author = {Dong Yang and Jing Wang and Zhijie Qu and Zezhong Liang and Xuchen Lin and Simon Weng and Xinkai Chen and Barbara Catinella and Luca Cortese and D. B. Fisher and Luis C. Ho and Yingjie Jing and Fangzhou Jiang and Peng Jiang and Ziming Liu and Céline Péroux and Li Shao and Lister Staveley-Smith and Q. Daniel Wang and Jie Wang}, doi = {10.3847/1538-4357/adbbe8}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {15}, shortjournal = {The Astrophys. J.}, title = {FEASTS combined with interferometry. IV. mapping h i emission to a limit of NH i = 1017.7 cm−2 in seven edge-on galaxies}, volume = {984}, year = {2025}, }
• (2025). Suprathermal electron scattering by narrowband whistler waves and broadband electrostatic waves: Parker solar probe observations. ApJ, 984(1), 14. (www)

  @article{ , abstract = {We utilize Parker Solar Probe measurements from the first nine perihelia to investigate suprathermal electron scattering near the Sun. We employ a normalized isotropy parameter to identify pitch-angle scattering (PAS) regions in the inner heliosphere, and compare the plasma conditions during these periods to the background (BG) solar wind. Suprathermal electron scattering also commonly occurs during full/partial current sheet (PCS) heliospheric current sheet (HCS) crossings, as identified in previous work. We find slightly higher electron collisional ages in the PAS and PCS/HCS regions than in BG regions, but conclude that Coulomb collisions alone likely cannot explain the observed suprathermal scattering. We investigate plasma wave-modes that could play a role in suprathermal electron scattering, and identify trends in the wave occurrence in BG, PAS, and PCS/HCS regions. We find higher occurrence rates of narrowband whistler-mode waves with frequencies of 0.04–0.19 f / f ce , and a higher occurrence of larger magnetic field wave power in this frequency band, in the PAS and PCS/HCS regions. These observations support the hypothesis that whistler-mode waves play a role in suprathermal electron scattering at moderate distances. However, closer to the Sun, narrowband whistlers are more rarely observed. Instead, we find higher occurrence rates of broadband electrostatic waves with frequencies of 0.1–4.4 f / f lh , and a higher occurrence of larger electric wave power in this band, in the near-Sun PAS and PCS/HCS regions. These observations suggest a role for broadband electrostatic waves in suprathermal electron scattering closer to the Sun.}, archive = {J_ApJ}, author = {Raaman Nair and Jasper S. Halekas and Cynthia Cattell and Michael Johnson and Elizabeth Hanson and Phyllis L. Whittlesey and Davin E. Larson and Roberto Livi and Justin C. Kasper and Michael L. Stevens and Stuart D. Bale and David M. Malaspina and Marc P. Pulupa}, doi = {10.3847/1538-4357/adbf1f}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {14}, shortjournal = {The Astrophys. J.}, title = {Suprathermal electron scattering by narrowband whistler waves and broadband electrostatic waves: Parker solar probe observations}, volume = {984}, year = {2025}, }
• (2025). JWST NIRCam simulations and observations of AGN ionization cones in cosmic noon galaxies. ApJ, 984(1), 13. (www)

  @article{ , abstract = {The extended narrow-line region (NLR) of active galactic nuclei (AGNs) provides a valuable laboratory for exploring the relationship between AGNs and their host galaxies, often appearing as an "ionization cone" that can extend out to the very edge of the galaxy. We use new James Webb Space Telescope NIRCam imaging to study the morphologies and sizes of NLRs traced by [O iii ] at cosmic noon ( z ∼ 2–3). To determine NIRCam's ability to probe the properties of the NLR in cosmic noon galaxies, we present simulated images of AGNs at z = 2–3 created with archival data cubes from the Multi Unit Spectroscopic Explorer of nine nearby ( z < 0.05) AGN host galaxies with previously confirmed extended NLRs. Our simulated images show that NIRCam is able to resolve the morphologies of NLRs at z = 2–3 with narrow- and medium-band observations. We then search for extended NLRs with NIRCam medium-band observations targeting the [O iii ] + H β emission in 27 previously identified AGNs at z = 2.4–3.4 in the Great Observatories Origins Deep Survey South field. We detect six galaxies in our observed sample with [O iii ] + H β morphologies consistent with AGN ionization cones with characteristic NLR sizes of 1–2.5 kpc. Thanks to our simulated data, we can predict the effects of cosmological surface brightness dimming and instrument noise on the NLR size measurements at high redshift, which has the biasing effect of lowering the NLR size–AGN luminosity trend that is observed at low redshift by a factor of ∼2.}, archive = {J_ApJ}, author = {S. Lebowitz and K. Hainline and S. Juneau and J. Lyu and C. C. Williams and S. Alberts and X. Fan and M. Rieke}, doi = {10.3847/1538-4357/adc07c}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {13}, shortjournal = {The Astrophys. J.}, title = {JWST NIRCam simulations and observations of AGN ionization cones in cosmic noon galaxies}, volume = {984}, year = {2025}, }
• (2025). Strong scatterings invalidate proposed models of enhanced tidal disruption event rates in post-starburst galaxies. ApJ, 984(1), 12. (www)

  @article{ , abstract = {Stars wandering too close to supermassive black holes (SMBHs) can be ripped apart by the tidal forces of the black hole. Recent optical surveys have revealed that E+A galaxies are over-represented by a factor of ∼30, while green galaxies are over-represented in both optical and IR surveys. Different stellar models have been proposed to explain this tidal disruption event (TDE) preference: ultrasteep stellar densities in the nuclear cluster, radial velocity anisotropies, and a top-heavy initial mass function (IMF). Here, we explore these hypotheses in the framework of our revised loss cone theory that accounts for both weak and strong scattering, i.e., a scattering strong enough to eject a star from the nuclear cluster. We find that when accounting for weak and strong scatterings, both ultrasteep densities and radial velocity anisotropies fail to explain the post-starburst preference of TDEs, except when considering a high anisotropy factor together with a high SMBH mass and a shallow density profile of stellar-mass BHs γ bh = 7/4. Our findings hold when combining either model with top-heavy IMFs. Hence, our work emphasizes both the importance of taking into account strong scatterings and the need for new hypotheses to explain the post-starburst preference of TDEs.}, archive = {J_ApJ}, author = {Odelia Teboul and Hagai B. Perets}, doi = {10.3847/1538-4357/adc09f}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {12}, shortjournal = {The Astrophys. J.}, title = {Strong scatterings invalidate proposed models of enhanced tidal disruption event rates in post-starburst galaxies}, volume = {984}, year = {2025}, }
• (2025). High-resolution observations of pickup-ion-mediated shocks to 60 au. ApJ, 984(1), 11. (www)

  @article{ , abstract = {This study provides a detailed analysis of 14 distant interplanetary shocks observed by the Solar Wind Around Pluto instrument on board New Horizons. These shocks were observed with a pickup ion data cadence of approximately 30 minutes, covering a heliocentric distance range of ∼52–60 au. All the shocks observed within this distance range are fast forward shocks, and the shock compression ratios vary between ∼1.2 and 1.9. The shock transition scales are generally narrow, and the SW density compressions are more pronounced compared to the previous study of seven shocks by D. J. McComas et al. A majority (64%) of these shocks have upstream sonic Mach numbers greater than 1. In addition, all high-resolution measurements of distant interplanetary shocks analyzed here show that the shock transition scale is independent of the shock compression ratio. However, the shock transition scale is strongly anticorrelated with the shock speed in the upstream plasma frame, meaning faster shocks generally yield sharper transitions.}, archive = {J_ApJ}, author = {Bishwas L. Shrestha and David J. McComas and Eric J. Zirnstein and George Livadiotis and Heather A. Elliott and Pontus C. Brandt and Alan Stern and Andrew R. Poppe and Joel Parker and Elena Provornikova and Kelsi Singer and Anne Verbiscer and New Horizons Heliophysics Team}, doi = {10.3847/1538-4357/adc0a1}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {11}, shortjournal = {The Astrophys. J.}, title = {High-resolution observations of pickup-ion-mediated shocks to 60 au}, volume = {984}, year = {2025}, }
• (2025). Thermal evolution of the plasma sheet region in the 2017 september 10 solar eruption. ApJ, 984(1), 10. (www)

  @article{ , abstract = {We conduct detailed thermal analysis of the plasma sheet region during the post-eruption phase of a flare that occurred on 2017 September 10, examining the thermal properties as both a function of space and time. The plasma sheet that develops is best observed using the 131 Å and 193 Å filters of the Atmospheric Imaging Assembly on the Solar Dynamics Observatory. We use the differential emission measure technique to calculate the emission measure, emission measure weighted average temperature, density, and thermal energy inside the plasma sheet region. These quantities are calculated as a function time to assess how the conditions of the plasma sheet region change throughout the duration of the event. We find that there is a minimal decrease in the temperature as the plasma sheet region evolves. The total thermal energy in the plasma sheet is on the order of 1.5–3.0 10 29 erg for the first 1.5 hr of the eruption and then decreases. For the first time for this event, we examine the conductive and radiative loss rates, which indicate rapid cooling should be expected, contradicting the temperature results. These findings suggest that there are underlying mechanisms such as adiabatic heating and/or turbulence-induced suppression of conduction that contribute to the sustained hot conditions in the plasma sheet.}, archive = {J_ApJ}, author = {DeOndre Kittrell and Katharine K. Reeves}, doi = {10.3847/1538-4357/adc115}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {10}, shortjournal = {The Astrophys. J.}, title = {Thermal evolution of the plasma sheet region in the 2017 september 10 solar eruption}, volume = {984}, year = {2025}, }
• (2025). Searching for accreting compact binary systems from spectroscopy and photometry: Application to LAMOST spectra. ApJ, 984(1), 9. (www)

  @article{ , abstract = {Compact objects undergoing mass transfer exhibit significant (and double-peaked) H α emission lines. Recently, new methods have been developed to identify black hole X-ray binaries and calculate their systematic parameters using H α line parameters, such as the full width at half-maximum (FWHM), equivalent width (EW), and separation of double peaks. In addition, the FWHM–EW plane from spectroscopy and the H α color–color diagram from photometry can be used for rapid stellar classification. We measure the H α and H β profiles (e.g., FWHM and EW) using the LAMOST DR9 low- and medium-resolution spectra, and calculate the systematic parameters (e.g., velocity semiamplitude of the donor star, mass ratio, inclination angle, and mass of the accretor). A new correlation between FWHM and K 2 , K 2 = 0.205(18) FWHM, is obtained for cataclysmic variables (CVs) in our sample. Both the FWHM–EW plane and the H α color–color diagram can distinguish CVs with FWHM ≳ 1000 km s −1 from Be stars and young stellar objects to some extent. To improve classification accuracy and enhance the selection of compact objects, we propose a new set of idealized filters with effective widths of 30, 130, and 400 Å for the narrow H α filter, broad H α filter, and r -band filter, respectively.}, archive = {J_ApJ}, author = {Xinlin Zhao and Song Wang and Jifeng Liu}, doi = {10.3847/1538-4357/adc1b9}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {9}, shortjournal = {The Astrophys. J.}, title = {Searching for accreting compact binary systems from spectroscopy and photometry: Application to LAMOST spectra}, volume = {984}, year = {2025}, }
• (2025). Stellar β−-decay rate of 63Ni and its impact on the s-process nucleosynthesis in massive stars. ApJ, 984(1), 8. (www)

  @article{ , abstract = {The β − -decay rate of 63 Ni, an important branching point, affects the subsequent nucleosynthesis in the weak component of the slow-neutron capture process (weak s -process). To evaluate the impact of the uncertainties of stellar lifetime of 63 Ni on abundances, we calculate the contribution to β − -decay rates from its excited states using the large-scale shell model with various interactions and also explore the atomic effects in the highly ionized plasma. In the core He burning stage and the shell C burning stage of massive stars, our new rates can be larger than those from K. Takahashi & K. Yokoi by up to a factor of 4 and 6, respectively. We evaluate the impact of the stellar decay rates of 63 Ni on the nucleosynthesis of A = 60 ∼ 90 in a star with an initial mass of 25 M ⊙ and solar metallicity. We find that the new rates can lead to abundance changes of 64 Ni, 63 Cu, 65 Cu, 64 Zn, 66 Zn, 67 Zn, and 68 Zn by up to 18%, 14%, 7%, 98%, 16%, 15%, and 13%, respectively, after the shell C burning stage at the Lagrangian mass coordinate M r = 2 M ⊙ . The enhancement of the decay rate of 63 Ni increases the weak s -process efficiency of nuclei after 65 Cu.}, archive = {J_ApJ}, author = {Xin-Xu Wang and Bao-Hua Sun and Toshitaka Kajino and Zhen-Yu He and Toshio Suzuki and Dong-Liang Fang and Zhong-Ming Niu}, doi = {10.3847/1538-4357/adc1be}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {8}, shortjournal = {The Astrophys. J.}, title = {Stellar β−-decay rate of 63Ni and its impact on the s-process nucleosynthesis in massive stars}, volume = {984}, year = {2025}, }
• (2025). A novel blast wave solution for the propagation of coronal and interplanetary shocks. ApJ, 984(1), 7. (www)

  @article{ , abstract = {Coronal mass ejections (CMEs) and their associated shock waves have severe space weather effects in the near-Earth space. Therefore, predicting the propagation and arrival time of the CME/shock is an important component of the space weather forecast. In this work, the analytical solutions for the propagation of blast waves are reorganized and derived, and a novel solution is obtained to describe their propagation in the background flow field moving at a constant speed. This novel solution can be used to predict the propagation and arrival time of the CME-associated shock waves in both the coronal and interplanetary medium. The input parameters of this novel solution are the shock wave's initial velocity, the piston-driving time in an analog of the initial blast process, and the background solar wind velocity. Based on the same initial conditions, we compare quantitatively the propagation processes of shock waves predicted by this novel solution and those predicted by other already existing models of the blast wave theory. The obtained results demonstrate the feasibility of this novel solution in predicting the arrival time of the interplanetary shock in the future.}, archive = {J_ApJ}, author = {Jiaqi Chai and Xinhua Zhao and Xueshang Feng and Nanbin Xiang and Shiwei Feng and Linhua Deng and Miao Wan and Tingting Xu}, doi = {10.3847/1538-4357/adc259}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {7}, shortjournal = {The Astrophys. J.}, title = {A novel blast wave solution for the propagation of coronal and interplanetary shocks}, volume = {984}, year = {2025}, }
• (2025). Energetic ion composition as a means of investigating the physical origins of alpha particle heavy magnetic switchbacks. ApJ, 984(1), 6. (www)

  @article{ , abstract = {Magnetic switchbacks are of continuing interest to the scientific community because the phenomenon has not been completely understood. Although most of the research into them in the Parker Solar Probe era has largely focused on creating a theoretical framework for causing the field reversal through magnetic interchange reconnection, reconnecting streams of plasma in the solar wind, or shear driven turbulence, it remains unclear as to what extent these models may or may not represent the underlying physical reality of magnetic switchbacks. In this paper, we present the results of our study on the energetic ion composition of magnetic switchback events using statistical methods with the aim of obtaining new insights into the underlying physics. In doing so, we find evidence that switchbacks containing suprathermal alpha flux display traits that are indicative of the Zank model of a magnetic "kink" propagating as a fast magnetosonic wave. These switchbacks also correlated with increased solar activity such as coronal mass ejections, high-speed streams, and solar flares. At the same time, switchbacks not meeting this criteria appear to occur at rates that are unaffected by increasing solar activity, which implies the existence of multiple populations of switchbacks with differing physical mechanisms behind them.}, archive = {J_ApJ}, author = {Emily McDougall and Bala Poduval}, doi = {10.3847/1538-4357/adc2ff}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {6}, shortjournal = {The Astrophys. J.}, title = {Energetic ion composition as a means of investigating the physical origins of alpha particle heavy magnetic switchbacks}, volume = {984}, year = {2025}, }
• (2025). Detection of an orphan X-ray flare from a blazar candidate EP240709a with the einstein probe. ApJ, 984(1), 5. (www)

  @article{ , abstract = {Blazars are often observed to flare across multiple wavelengths. Orphan flares from blazars have only been detected a few times, providing an opportunity to understand the structure of the jet in the accreting system. We report a remarkable orphan X-ray flare from a blazar candidate EP240709a, detected by the Einstein Probe (EP) in July 2024. The multiband spectral properties and variability support EP240709a as a high-energy peaked BL Lacertae-type object. The flux in 0.5–10 keV increased by at least 28 times to the value of low state in 2020, with no significant flaring detected in other bands during the same period. EP240709a exhibits the harder-when-brighter tendency in the X-ray band during the orphan flare, while its infrared-optical spectra are featureless. We employ one-zone and two-zone leptonic synchrotron self-Compton models to perform the spectral energy distribution fitting. Detecting this rare orphan flare shows the potential of EP in discovering peculiar activities from AGN in high-cadence X-ray sky surveys.}, archive = {J_ApJ}, author = {Mingjun Liu and Yijia Zhang and Yun Wang and Rui Xue and David Buckley and D. Andrew Howell and Chichuan Jin and Wenxiong Li and Itumeleng Monageng and Haiwu Pan and Ning-Chen Sun and Samaporn Tinyanont and Lingzhi Wang and Weimin Yuan and Jie An and Moira Andrews and Rungrit Anutarawiramkul and Pathompong Butpan and Yong Chen and Huaqing Cheng and Weiwei Cui and Cui-Yuan Dai and Lixin Dai and Joseph Farah and Hua Feng and Shaoyu Fu and Zhen Guo and Shumei Jia and Shuaiqing Jiang and An Li and Chengkui Li and Dongyue Li and Tianying Lian and Yifang Liang and Heyang Liu and Xing Liu and Yuan Liu and Jirong Mao and Curtis McCully and Megan Newsome and Estefania Padilla Gonzalez and Xin Pan and Xinxiang Sun and Giacomo Terreran and Ze-Rui Wang and Qinyu Wu and Hubing Xiao and Dingrong Xiong and Dong Xu and Xinpeng Xu and Suijian Xue and Haonan Yang and Jun Yang and Jin Zhang and Wenda Zhang and Wenjie Zhang and Hu Zou}, doi = {10.3847/1538-4357/adc301}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {5}, shortjournal = {The Astrophys. J.}, title = {Detection of an orphan X-ray flare from a blazar candidate EP240709a with the einstein probe}, volume = {984}, year = {2025}, }
• (2025). The observations of magnetic reconnection during the interaction process of two active region filaments. ApJ, 984(1), 4. (www)

  @article{ , abstract = {We investigate the interaction between two filaments (F1 and F2) and their subsequent magnetic reconnection in active region (AR) NOAA 13296 and AR NOAA 13293 on 2023 May 9, utilizing high spatial and temporal resolution and multiwavelength observational data from the Solar Dynamics Observatory, the New Vacuum Solar Telescope, and the Chinese H α Solar Explorer. The movement of F1 from the southeast toward the northwest, driven by the motion of the positive magnetic polarity (P1), leads to a collision and reconnection with F2. This reconnection exchanges their footpoints, resulting in the formation of two new filaments (F3 and F4) consistent with "slingshot" type filament interaction. During the interaction, the current sheet, moving due to the motion of F1, and the reconnection outflows, moving along F3 and F4, were both observed. The current sheet is rarely observed in the slingshot type filament interaction, measuring approximately 2.17 Mm in length and 0.84 Mm in width. After the interaction, the F1 disappears, whereas a portion of F2 remains, indicating that the interaction involves partial slingshot reconnection, due to the unequal magnetic flux between the filaments. The residual part of F2 will undergo another magnetic reconnection in the same interaction region with the magnetic loops connecting polarities N1 and P1. The material generated by the reconnection is continuously injected into F4, leading to its final morphology. The findings enhance our understanding of slingshot-type filament interactions, indicating that partial slingshot reconnections between filaments may be more common than full slingshot events.}, archive = {J_ApJ}, author = {Zongyin Wu and Zhike Xue and Xiaoli Yan and Jincheng Wang and Liheng Yang and Zhe Xu and Qiaoling Li and Yang Peng and Liping Yang and Yian Zhou and Xinsheng Zhang and Liufan Gong and Qifan Dong and Guotang Wu}, doi = {10.3847/1538-4357/adc377}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {4}, shortjournal = {The Astrophys. J.}, title = {The observations of magnetic reconnection during the interaction process of two active region filaments}, volume = {984}, year = {2025}, }
• (2025). Upper limits on the gamma-ray emission from the microquasar v4641 sgr. ApJ, 984(1), 3. (www)

  @article{ , abstract = {Following a recent detection of TeV radiation by the Large High Altitude Air Shower Observatory and the High-Altitude Water Cherenkov Observatory, coincident with the direction of the microquasar V4641 Sgr, we search for possible GeV emission from this source. We explored the morphology and temporal features of the source as well as two nearby unassociated point sources, which could be a part of the extended structure of V4641 Sgr, and compared results with corresponding X-ray and TeV emissions. No significant gamma-ray signal linked to V4641 Sgr was detected in the energy range of 1–300 GeV. The 95% confidence level upper limits for the flux from the source, assuming both point and extended source models, were 5.38 × 10 −13 erg cm −2 s −1 and 1.12 × 10 −12 erg cm −2 s −1 , respectively. Additionally, no correlation between the gamma-ray light curve and X-ray outbursts was observed.}, archive = {J_ApJ}, author = {Zihao Zhao and Jian Li and Diego F. Torres}, doi = {10.3847/1538-4357/adc39c}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {3}, shortjournal = {The Astrophys. J.}, title = {Upper limits on the gamma-ray emission from the microquasar v4641 sgr}, volume = {984}, year = {2025}, }
• (2025). Impact of spectral resolution on S-index and its application to spectroscopic surveys. ApJ, 984(1), 2. (www)

  @article{ , abstract = {Utilizing the PHOENIX synthetic spectra, we investigated the impact of spectral resolution on the calculation of S -indices. We found that for spectra with a resolution lower than ≈30,000, it is crucial to calibrate S -indices for accurate estimations. This is especially essential for low-resolution spectral observations. We provided calibrations for several ongoing or upcoming spectroscopic surveys such as the LAMOST low-resolution survey, the SEGUE survey, the Sloan Digital Sky Survey-V/BOSS survey, the DESI survey, the Maunakea Spectroscopic Explorer survey, and the MUST survey. Using common targets between the HARPS and Mount Wilson Observatory (MWO) observations, we established conversions from spectral S -indices to the well-known S MWO values, applicable to stars with [Fe/H] values greater than −1. These calibrations offer a reliable approach to converting S -indices obtained from various spectroscopic surveys into S MWO values and can be widely applied in studies on chromospheric activity.}, archive = {J_ApJ}, author = {Henggeng Han and Song Wang and Xue Li and Chuanjie Zheng and Jifeng Liu}, doi = {10.3847/1538-4357/adc600}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {2}, shortjournal = {The Astrophys. J.}, title = {Impact of spectral resolution on S-index and its application to spectroscopic surveys}, volume = {984}, year = {2025}, }
• (2025). The efficiency of harmonic emissions excited by energetic electrons in coronal loops. ApJ, 984(1), 1. (www)

  @article{ , abstract = {Magnetic reconnection is a key process that drives the energy release in solar flares. This process can occur at multiple locations along the coronal loop. The reconnection generates energetic electrons capable of exciting wave modes and emissions as they propagate through the loop. In this follow-up study, we investigate the influence of the injection site location of these energetic electrons, either at the looptop (LT) or at the leg of the loop around a footpoint (FP), on the excitation of wave modes, especially the second harmonic emissions (X2) in coronal loops. Our simulations reveal that the injection location significantly impacts the spatial distribution and intensity of excited wave modes. When electrons are injected at the LT, electromagnetic X 2, and Z -modes dominate along the loop, with minimal excitation of Langmuir waves. Conversely, the present study reveals that injection close to FP leads to a strong Langmuir wave excitation throughout the loop, particularly as electrons ascend toward the LT. We find that X 2 and Z -modes are consistently excited at the injection site with different intensities, regardless of the injection location. However, electron injection near the FP scenario creates favorable conditions for significant Langmuir wave generation, potentially leading to plasma emission under specific circumstances. These findings emphasize the importance of electron injection location in determining the properties of the excited and emitted waves in solar coronal loops.}, archive = {J_ApJ}, author = {Mehdi Yousefzadeh and Alexey Kuznetsov and Yao Chen and Mahboub Hosseinpour}, doi = {10.3847/1538-4357/adc72f}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {1}, shortjournal = {The Astrophys. J.}, title = {The efficiency of harmonic emissions excited by energetic electrons in coronal loops}, volume = {984}, year = {2025}, }
• (2025). Erratum: “Spectral variations across latitudes on asteroid (3200) phaethon” (2025, ApJ, 980, 127). ApJ, 983(2), 189. (www)

  @article{ , archive = {J_ApJ}, author = {M. Angrisani and E. Palomba and A. Longobardo and E. Rognini and A. Migliorini and E. D’Aversa and G. Pratesi and C. Gisellu and F. Dirri and L. Piazzo and T. Arai}, doi = {10.3847/1538-4357/adc5fb}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {189}, shortjournal = {The Astrophys. J.}, title = {Erratum: “Spectral variations across latitudes on asteroid (3200) phaethon” (2025, ApJ, 980, 127)}, volume = {983}, year = {2025}, }
• (2025). Erratum: “The structure of the molecular envelope of the ring nebula (NGC 6720)” (2025, ApJ, 981, 46). ApJ, 983(2), 188. (www)

  @article{ , archive = {J_ApJ}, author = {Joel H. Kastner and David J. Wilner and Diana Ryder and Paula Moraga Baez and Orsola De Marco and Raghvendra Sahai and Al Wootten and Albert Zijlstra}, doi = {10.3847/1538-4357/adc688}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {188}, shortjournal = {The Astrophys. J.}, title = {Erratum: “The structure of the molecular envelope of the ring nebula (NGC 6720)” (2025, ApJ, 981, 46)}, volume = {983}, year = {2025}, }
• (2025). Erratum: “Evidence of ultrafaint radio frequency interference in deep 21 cm epoch of reionization power spectra with the murchison wide-field array” (2023, ApJ, 957, 78). ApJ, 983(2), 187. (www)

  @article{ , archive = {J_ApJ}, author = {Michael J. Wilensky and Miguel F. Morales and Bryna J. Hazelton and Pyxie L. Star and Nichole Barry and Ruby Byrne and C. H. Jordan and Daniel C. Jacobs and Jonathan C. Pober and C. M. Trott}, doi = {10.3847/1538-4357/adc813}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {187}, shortjournal = {The Astrophys. J.}, title = {Erratum: “Evidence of ultrafaint radio frequency interference in deep 21 cm epoch of reionization power spectra with the murchison wide-field array” (2023, ApJ, 957, 78)}, volume = {983}, year = {2025}, }
• (2025). Tracing the evolution of the cool gas in CGM and IGM environments through mg ii absorption from redshift z = 0.75 to z = 1.65 using DESI-y1 data. ApJ, 983(2), 186. (www)

  @article{ , abstract = {We present a measurement of the mean absorption of cool gas traced by Mg ii ( λλ 2796, 2803) around emission line galaxies (ELGs), spanning spatial scales from 20 kpc to 10 Mpc. The measurement is based on crossmatching the positions ELGs at z = 0.75–1.65 and the metal absorption in the spectra of background quasars with data provided by the Year 1 sample of the Dark Energy Spectroscopic Instrument. The ELGs are divided into two redshift intervals: 0.75 < z < 1.0 and 1.0 < z < 1.65. We find that the composite quasar spectra constructed by stacking the ELG-QSO pairs evolve with redshift, with z > 1 having a systematically higher signal of Mg ii absorption. Within 1 Mpc, the covering fraction of the cool gas at z > 1 is higher than that of z < 1. The enhancement becomes less apparent especially if the projected distance r p > 1 Mpc. ELGs with higher stellar mass and star formation rate (SFR) yield higher clustering of Mg ii absorbers at z < 1. For z > 1, the covering fractions with different SFRs show little difference. The higher Mg ii absorption at higher redshift supports the observations of higher star formation at cosmic noon. Converting the Mg ii absorbers to unsaturated Si ii , our estimate indicates that the metal abundance of Si ii ranges from 0.7 to 1.2 × 10 −6 from z = 0.9 to 1.3. The growth of low-ionization metal abundance strongly suggests a metal-enriched circumgalactic medium and an increased presence of cool gas in the intergalactic medium toward higher redshifts.}, archive = {J_ApJ}, author = {Xuanyi Wu and Z. Cai and T.-W. Lan and S. Zou and A. Anand and Biprateep Dey and Z. Li and J. Aguilar and S. Ahlen and D. Brooks and T. Claybaugh and A. de la Macorra and P. Doel and S. Ferraro and J. E. Forero-Romero and S. Gontcho A Gontcho and K. Honscheid and S. Juneau and R. Kehoe and T. Kisner and A. Lambert and M. Landriau and L. Le Guillou and M. Manera and A. Meisner and R. Miquel and J. Moustakas and J. A. Newman and F. Prada and G. Rossi and E. Sanchez and D. Schlegel and M. Schubnell and M. Siudek and D. Sprayberry and G. Tarlé and B. A. Weaver and H. Zou}, doi = {10.3847/1538-4357/adb28a}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {186}, shortjournal = {The Astrophys. J.}, title = {Tracing the evolution of the cool gas in CGM and IGM environments through mg ii absorption from redshift z = 0.75 to z = 1.65 using DESI-y1 data}, volume = {983}, year = {2025}, }
• (2025). Machine and deep learning–driven angular momentum inference from BHEX observations of the n = 1 photon ring. ApJ, 983(2), 185. (www)

  @article{ , abstract = {The n = 1 photon ring is an important probe of black hole (BH) properties and will be resolved by the Black Hole Explorer (BHEX) for the first time. However, extraction of black hole parameters from observations of the n = 1 subring is not trivial. Developing this capability can be achieved by building a sample of n = 1 subring simulations, as well as by performing feature extraction on this high-volume sample to track changes in the geometry, which presents significant computational challenges. Here, we present a framework for the study of n = 1 photon-ring behavior and BH property measurement from BHEX images. We use KerrBAM to generate a grid of ≳10 6 images of n = 1 photon rings spanning the entire space of Kerr BH spins and inclinations. Intensity profiles are extracted from images using a novel feature-extraction method developed specifically for BHEX. This novel method is highly optimized and outperforms existing Event Horizon Telescope methods by a factor of ∼3000. Additionally, we propose a novel, minimal set of geometric measurables for characterizing the behavior of the n = 1 subring geometry. We apply these measurables to our simulation grid and test spin recovery on simulated images using (i) gradient boosting, a machine learning algorithm, and (ii) an extension of Deep Horizon, a deep learning framework. We find ≳90% correct recovery of BH properties using the machine/deep learning approaches, and characterize the space of resolution-dependent geometric degeneracies. Finally, we test both approaches on general relativistic magnetohydrodynamic simulations of black hole accretion flows, and report accurate recovery of spin at the expected inclination of M87*.}, archive = {J_ApJ}, author = {Joseph Farah and Jordy Davelaar and Daniel Palumbo and Michael Johnson and Jonathan Delgado}, doi = {10.3847/1538-4357/adbbe3}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {185}, shortjournal = {The Astrophys. J.}, title = {Machine and deep learning–driven angular momentum inference from BHEX observations of the n = 1 photon ring}, volume = {983}, year = {2025}, }
• (2025). The JCMT BISTRO survey: Unveiling the magnetic fields around galactic center. ApJ, 983(2), 184. (www)

  @article{ , abstract = {We acquired 450 and 850 μ m dust continuum polarization observations toward the inner region of the Central Molecular Zone (CMZ) as part of the B -Fields In Star-forming Region Observations survey using the POL-2 polarimeter on the James Clerk Maxwell Telescope. These observations encompassed three dense structures: the 20 km s −1 cloud (20MC), 50 km s −1 cloud (50MC), and circumnuclear disk (CND). Our aim is to investigate the magnetic field morphology and strength in the inner region of the CMZ using polarized dust continuum and the Davis–Chandrasekhar–Fermi method. The magnetic field morphology is highly ordered in all three dense regions. The plane-of-sky magnetic field strengths are ∼1 mG for the 20MC and the 50MC, and ∼2 mG for the CND. We compare the energy contributions of turbulence, gravity, and thermal motion with that of the magnetic field using the plasma β , mass-to-flux ratio, and Alfvén Mach number. The outcomes reveal the magnetic field stands out as the predominant factor within the inner region of the CMZ. The dominance of the magnetic field may explain the low star-forming rate in the CMZ. We further investigate the dust grain alignment efficiency by exploring the relationship between polarization fraction and total intensity. The results suggest that dust grains are well aligned with the magnetic fields.}, archive = {J_ApJ}, author = {Meng-Zhe Yang and Shih-Ping Lai and Janik Karoly and Kate Pattle and Xing Lu and David Eden and Sheng-Jun Lin and Frédérick Poidevin and Ekta Sharma and Jihye Hwang and Lapo Fanciullo and Mehrnoosh Tahani and Patrick M. Koch and Shu-ichiro Inutsuka and Valentin J. M. Le Gouellec and Hao-Yuan Duan and Jia-Wei Wang and Gary Fuller and Ray S. Furuya and Qilao Gu and Tetsuo Hasegawa and Guangxing Li and Junhao Liu and M. S. Akshaya and Bijas Najimudeen and Le Ngoc Tram and Derek Ward-Thompson and Doris Arzoumanian and James Di Francesco and Yasuo Doi and Thiem Hoang and Ji-hyun Kang and Jungmi Kwon and Woojin Kwon and Chang Won Lee and Tie Liu and Takashi Onaka and Sarah Sadavoy and Motohide Tamura and Pierre Bastien and David Berry and Simon Coudé and Keping Qiu}, doi = {10.3847/1538-4357/adbe34}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {184}, shortjournal = {The Astrophys. J.}, title = {The JCMT BISTRO survey: Unveiling the magnetic fields around galactic center}, volume = {983}, year = {2025}, }
• (2025). One galaxy sample to rule them all: Halo occupation distribution modeling of DES year 3 source galaxies. ApJ, 983(2), 183. (www)

  @article{ , abstract = {For the joint analysis of second-order weak-lensing and galaxy clustering statistics, so-called 3 × 2 analyses, the selection and characterization of optimal galaxy samples is a major area of research. One promising choice is to use the same galaxy sample as lenses and sources, which reduces the systematics parameter space that describes the uncertainties related to galaxy samples. Such a "lens-equal-source" analysis significantly improves the self-calibration of photo- z systematics, leading to improved cosmological constraints. With the aim of enabling a lens-equal-source analysis on small scales, we investigate the halo–galaxy connection of DES Year 3 source galaxies. We develop a technique to construct mock source galaxy populations by matching COSMOS/UltraVISTA photometry to U niverse M achine galaxies. These mocks predict a source halo occupation distribution (HOD) that exhibits significant redshift evolution, nontrivial central incompleteness, and galaxy assembly bias. We produce multiple realizations of mock source galaxies drawn from the U niverse M achine posterior, with added uncertainties in the measured Dark Energy Survey photometry and galaxy shapes. We fit a modified HOD formalism to these realizations to produce priors on the galaxy–halo connection for cosmological analyses. We additionally train an emulator that predicts this HOD to  ∼2% accuracy from redshift z = 0.1−1.3 that models the dependence of this HOD on (1) observational uncertainties in galaxy size and photometry and (2) uncertainties in the U niverse M achine predictions.}, archive = {J_ApJ}, author = {Andrés N. Salcedo and Tim Eifler and Peter Behroozi}, doi = {10.3847/1538-4357/adc09a}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {183}, shortjournal = {The Astrophys. J.}, title = {One galaxy sample to rule them all: Halo occupation distribution modeling of DES year 3 source galaxies}, volume = {983}, year = {2025}, }
• (2025). Ring or no Ring—Revisiting the multiphase nuclear environment in m31. ApJ, 983(2), 182. (www)

  @article{ , abstract = {Nuclear rings, prevalent in barred galaxies, are essential to understanding gas transport toward galactic nuclei. However, the peculiar nuclear ring in our neighboring galaxy M31 remains poorly understood. Here we present a comprehensive study of this multiphase gas structure, originally revealed by its dust emission, based on newly acquired CO mappings and archival spectroscopic imaging of atomic hydrogen and warm ionized gas, along with custom numerical simulations. These multiwavelength data offer an unprecedented view of the surface mass density and kinematics of the nuclear ring, challenging the notion of it being a single coherent structure. In particular, the ring shows significant asymmetry in its azimuthal mass distribution, with neutral gas concentrated in the northeast and ionized gas prominent in the southwest. The observed off-centered and lopsided morphology disfavors an interpretation as gas streamers or resonance rings driven solely by a barred potential known to exist in M31. Furthermore, the ring's line-of-sight velocity distribution suggests circular motion in a plane inclined by ∼30° relative to M31's outer disk, implying external torque likely from M32's recent close-in passage. Our hydrodynamical simulations tracking the evolution of nuclear gas in M31 influenced by both a barred potential and an oblique collision with M32 reveal the natural formation of asymmetric spiral arms several hundred Myr after the collision, which could appear ringlike at appropriate viewing angles. Therefore, we suggest that M31's nuclear gas structure, instead of being a persistent rotating ring, comprises recently formed, asymmetric spirals with a substantial tilt.}, archive = {J_ApJ}, author = {Zongnan Li and Zhao Su and Sumin Wang and Yufan F. Zhou and Zhiyuan Li and Xuanyi Lyu and Fanyi Meng and Kai Zhang and Di Li and Chaowei Tsai and Jingwen Wu and Jiachang Zhang}, doi = {10.3847/1538-4357/adc103}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {182}, shortjournal = {The Astrophys. J.}, title = {Ring or no Ring—Revisiting the multiphase nuclear environment in m31}, volume = {983}, year = {2025}, }
• (2025). Reconstructing star formation histories of high-redshift galaxies: A comparison of resolved parametric and nonparametric models. ApJ, 983(2), 181. (www)

  @article{ , abstract = {We investigate the optimal approach for recovering the star formation histories (SFHs) and spatial distribution of stellar mass in high-redshift galaxies ( z ∼ 2–5), focusing on the impact of assumed SFH models on derived galaxy properties. Utilizing pixel-by-pixel spectral energy distribution (SED) fitting of multiband photometry, we explore various parametric SFH models (including exponentially declining ( τ ), delayed- τ , lognormal, and double power law) alongside spatially resolved nonparametric (NPM) methods. We first analyze the models using simulated galaxies and then apply them to observed galaxies for validation and as proof of concept, with additional comparisons to results from unresolved SED fitting. Our findings demonstrate that pixel-by-pixel analysis with parametric models is particularly robust in recovering the true SFHs of simulated galaxies, with the double-power-law (DPL) model outperforming others, including NPM methods. This model excels in detecting recent starbursts within the last 500 Myr and capturing the stochastic nature of star formation. Conversely, unresolved photometry with simplistic parametric models tends to produce biased estimates of key galaxy properties, particularly underestimating early star formation. NPM methods, resolved or unresolved, typically yield older mass-weighted ages. Biases in early-time star formation rates, likely introduced by prior assumptions, further complicate these models. We conclude that the DPL model, applied in a pixel-by-pixel framework, offers the most reliable recovery of SFHs and produces robust stellar mass maps. Resolved methods simplify modeling dust and metallicity, enhancing parameter interpretability and underscoring the value of flexible parametric models in spatially resolved analyses.}, archive = {J_ApJ}, author = {Moein Mosleh and Mohammad Riahi-Zamin and Sandro Tacchella}, doi = {10.3847/1538-4357/adc12e}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {181}, shortjournal = {The Astrophys. J.}, title = {Reconstructing star formation histories of high-redshift galaxies: A comparison of resolved parametric and nonparametric models}, volume = {983}, year = {2025}, }
• (2025). Interplanetary magnetic field curvature and its role in particle acceleration: Magnetospheric multiscale and solar orbiter observations. ApJ, 983(2), 180. (www)

  @article{ , abstract = {The curvature of the magnetic field plays a crucial role in magnetic confinement, magnetic reconnection, particle heating, and acceleration. Though the magnetic field curvature has been sufficiently investigated in the terrestrial magnetosheath, there is a lack of research in the more extensive interplanetary space. This study, combining the Magnetospheric Multiscale and Solar Orbiter (SolO) observations, investigates the magnetic field curvature in the near-Earth and interplanetary space. The spatial distributions and probability distribution functions (PDFs) of the curvature are revealed in the solar wind, magnetosheath, and magnetosphere. It shown that the field curvature in the solar wind follows a two-power-law PDF, similar to that in the magnetosheath but with distinct exponents. We then extend the research to a heliocentric distance of [0.3, 1.0] au, with the aid of an indirect estimation method of magnetic field curvature that can be applied to the SolO data. The average curvature, as a function of heliocentric distance, exhibits a U-shape variation with the minimum curvature appearing at 0.5 au. A possible explanation for such a variation is also given and supported by the spacecraft data. This work could improve our understanding of the turbulent environment in the interplanetary space and demonstrate the universality of a recently proposed acceleration scenario of electrons due to the interaction of shocks and curved magnetic field lines.}, archive = {J_ApJ}, author = {D. K. Hu and Y. Y. Liu and J. B. Cao and C. M. Liu and Y. T. Song}, doi = {10.3847/1538-4357/adc1c7}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {180}, shortjournal = {The Astrophys. J.}, title = {Interplanetary magnetic field curvature and its role in particle acceleration: Magnetospheric multiscale and solar orbiter observations}, volume = {983}, year = {2025}, }
• (2025). The emission geometry of pulsars with interpulses. ApJ, 983(2), 179. (www)

  @article{ , abstract = {We present polarization profiles of 23 pulsars exhibiting interpulse (IP) emissions using the Five-hundred-meter Aperture Spherical Radio Telescope. By applying the rotating vector model (RVM), we measured the inclination and impact angles for 16 pulsars, allowing us to investigate their beam geometries. Our analysis indicates that for five pulsars, the IP emissions likely originate from the same magnetic pole as the main pulse (MP), whereas for the remaining 11 pulsars, the IP and MP emissions originate from opposite magnetic poles. For the seven pulsars that do not conform to the RVM, we are unable to determine whether the IP emissions originate from the same or opposite magnetic pole as the MPs. By analyzing the beam configurations of pulsars, we found that the emission within the beam is not fully active across both longitude and latitude. Filling factors ranging from 0.27 to 0.99 were obtained for pulsars with opposite pole IP emissions, suggesting an underestimation of emission height when applying the geometrical method. The emissions for MPs and IPs occur at different heights in the pulsar magnetosphere, with the difference in emission height ranging from tens to thousands of kilometers. We also found that some pulsars have wide emission beams, indicating that radio emissions may occur in regions of high altitude within the pulsar magnetosphere.}, archive = {J_ApJ}, author = {S. N. Sun and N. Wang and W. M. Yan and S. Q. Wang}, doi = {10.3847/1538-4357/adc254}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {179}, shortjournal = {The Astrophys. J.}, title = {The emission geometry of pulsars with interpulses}, volume = {983}, year = {2025}, }
• (2025). Detection of anisotropies in the circumgalactic medium of disk galaxies: Supermassive black hole activity or star formation-driven outflows?. ApJ, 983(2), 178. (www)

  @article{ , abstract = {Gamma and X-ray observatories have revealed spectacular structures in the emission of the tenuous hot gas surrounding the Milky Way (MW), known as the Fermi and extended ROentgen Survey with an Imaging Telescope Array (eROSITA) bubbles. Galaxy formation simulations suggest that MW-like bubbles could be ubiquitous, but their emission may be too faint to detect with today's instruments in individual external galaxies. In this paper, we present an analysis of stacked Chandra observations of 93 nearby galaxies. We detected soft, diffuse X-rays from the circumgalactic medium (CGM), extending up to 14 kpc, with a luminosity of (4.2 ± 0.7) × 10 39 erg s −1 in the 0.3−2 keV band. To probe its spatial distribution, we constructed an azimuthal profile and found a significant enhancement along the galactic minor axis. When dividing our sample by stellar mass, central supermassive black hole (SMBH) mass, and star formation rate (SFR), we found that only high-SFR galaxies exhibit significant anisotropies in the CGM emission. To investigate whether the observed anisotropies could be attributed to MW-like bubbles, we compared our results with TNG50 simulations. In these simulations, X-ray bubbles are strongly correlated with mass of the central SMBH and typically extend to much larger, ∼50 kpc, scales. We conclude that the observed anisotropies are either caused by active galactic nucleus–driven MW-like bubbles confined to smaller, ∼10 kpc, scales or by star formation– or starburst-driven bubbles/outflows.}, archive = {J_ApJ}, author = {Andrea Sacchi and Ákos Bogdán and Nhut Truong}, doi = {10.3847/1538-4357/adc38b}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {178}, shortjournal = {The Astrophys. J.}, title = {Detection of anisotropies in the circumgalactic medium of disk galaxies: Supermassive black hole activity or star formation-driven outflows?}, volume = {983}, year = {2025}, }
• (2025). Once a giant, (Almost) always a giant: Partial tidal disruption events of giant stars. ApJ, 983(2), 177. (www)

  @article{ , abstract = {Tidal disruption events (TDEs) of giant stars by supermassive black holes (SMBH) differ significantly from those of main-sequence ones. Most (all for SMBH of more than a few × 10 5 m ⊙ ) giant TDEs are partial: only a fraction of the envelope is torn apart. The dense stellar core and the rest of the envelope remain intact. In this work we explore, using the stellar evolution code MESA , the fate of the remnants. We find that after a short period, comparable to the thermal timescale, the remnant returns to a giant structure with a radius comparable to the progenitor giant one, a slightly larger luminosity (as compared with a regular giant with the same mass), and a comparable lifetime until it collapses to a white dwarf. If such a giant with a mass less than ≈0.9 m ⊙ is discovered, it can be identified as an outlier—a giant that is too light for the current age of the Universe. If the remnant orbit is not perturbed significantly during the encounter, the remnant will undergo successive partial tidal disruptions until its mass is 0.6–0.7 m ⊙ . We expect a few dozen to a few hundred such remnants in the Galactic nucleus.}, archive = {J_ApJ}, author = {Núria Navarro Navarro and Tsvi Piran}, doi = {10.3847/1538-4357/ad96b7}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {177}, shortjournal = {The Astrophys. J.}, title = {Once a giant, (Almost) always a giant: Partial tidal disruption events of giant stars}, volume = {983}, year = {2025}, }
• (2025). The signatures of density fluctuations and mixing gas in circumgalactic absorption systems. ApJ, 983(2), 176. (www)

  @article{ , abstract = {We investigate the prospects for detecting and constraining density and temperature inhomogeneities in the circumgalactic medium using absorption measurements of metal ions. Distributions in the gas thermal properties could arise from turbulence, gas cooling from the hot phase, and mixing between the cool and hot phases. Focusing on these physically motivated models, we parameterize each with a single parameter for simplicity and provide empirical and theoretical estimates for reasonable parameter values. We then construct the probability distribution functions for each of these scenarios, calculate the effective ion fractions, and fit our models to the COS-Halos absorption measurements to infer the gas densities and metallicities. We find that the models we consider (i) produce similarly good fits to the observations with or without distributions in the gas thermal properties, and (ii) result in detectable changes in the column densities only at the boundaries of reasonable parameter values. We show that He ii self-shielding can have a larger effect on the ion fractions than density and temperature fluctuations. As a result, uncertainties in cloud geometry and their spatial distribution, affecting the details of radiation transfer, may obscure the effect of inhomogeneities.}, archive = {J_ApJ}, author = {Yakov Faerman and Daniel R. Piacitelli and Matthew McQuinn and Jessica K. Werk}, doi = {10.3847/1538-4357/ada773}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {176}, shortjournal = {The Astrophys. J.}, title = {The signatures of density fluctuations and mixing gas in circumgalactic absorption systems}, volume = {983}, year = {2025}, }
• (2025). Searching for internal absorption signatures in high-redshift blazars. ApJ, 983(2), 175. (www)

  @article{ , abstract = {The γ -ray emission from flat spectrum radio quasars (FSRQs), a subclass of blazars, is believed to be generated through interactions of high-energy leptons and/or hadrons in the jet with the ambient photon fields, including those from the accretion disk, the broad line region (BLR), and the dusty torus. However, these same photon fields can also attenuate γ -rays through internal photon–photon ( γ – γ ) absorption, imprinting characteristic spectral features. Investigating the internal absorption is crucial for unraveling the complex structure of FSRQs and constraining the poorly known location of the γ -ray emission region. In this study, we select a sample of γ -ray detected FSRQs with high redshift ( z ≳ 3) to search for absorption features appearing at lower photon energies due to a substantial redshift. We extract the Fermi Large Area Telescope γ -ray spectra of these sources and perform physical modeling using a detailed γ – γ opacity model, assuming that the BLR photon field dominates the absorption and focusing on the energy range ∼25 GeV/(1 + z ), where the absorption feature due to Ly α photons is expected. Our analysis reveals a hint of internal absorption for one source (the lowest redshift object in our sample, z ≃ 3) and provides constraints on the location of its γ -ray emitting region along the jet. For the remaining, higher-redshift sources, the limited photon statistics prevent a reliable detection of internal opacity features.}, archive = {J_ApJ}, author = {A. Dmytriiev and A. Acharyya and M. Böttcher}, doi = {10.3847/1538-4357/adb398}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {175}, shortjournal = {The Astrophys. J.}, title = {Searching for internal absorption signatures in high-redshift blazars}, volume = {983}, year = {2025}, }
• (2025). The dependence of polarization degree of blazars on particle energy distributions. ApJ, 983(2), 174. (www)

  @article{ , abstract = {We present a formalism to predict the polarization degree (PD) for synchrotron emission from particles having a specified energy distribution in the presence of an ordered and random magnetic field configuration. The broadband spectral energy distribution and the X-ray and optical PD data for Mrk 501 have been fitted using the formalism. As reported earlier, we find that for a broken power-law particle energy distribution the PD cannot be explained, unless it is assumed that the higher-energy particles experience a higher ordered magnetic field compared to the lower-energy ones. On the other hand, a log parabola particle energy distribution can explain the observed higher X-ray PD compared to the optical, even when all the particles experience the same magnetic configuration. We discuss the possibility of distinguishing the two scenarios using future observations.}, archive = {J_ApJ}, author = {Ranjeev Misra and Hritwik Bora and Rupjyoti Gogoi}, doi = {10.3847/1538-4357/adbbb6}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {174}, shortjournal = {The Astrophys. J.}, title = {The dependence of polarization degree of blazars on particle energy distributions}, volume = {983}, year = {2025}, }
• (2025). Identifying catastrophic outlier photometric redshift estimates in the COSMOS field with machine learning methods. ApJ, 983(2), 173. (www)

  @article{ , abstract = {We present the result of two binary classifier ensembled neural networks to identify catastrophic outliers for photo- z estimates within the COSMOS field utilizing only eight and five photometric bandpasses, respectively. Our neural networks can correctly classify 55.6% and 33.3% of the true positives with few to no false positives. These methods can be used to reduce the errors caused by the errors in redshift estimates, particularly at high redshift. When applied to a larger data set with only photometric data available, our eight bandpass network increased the number of objects with a photo- z greater than five from 0.1% to 1.6%, and our five bandpass network increased the number of objects with a photo- z greater than five from 0.2% to 1.8%.}, archive = {J_ApJ}, author = {Mitchell T. Dennis and Esther M. Hu and Lennox L. Cowie}, doi = {10.3847/1538-4357/adbe62}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {173}, shortjournal = {The Astrophys. J.}, title = {Identifying catastrophic outlier photometric redshift estimates in the COSMOS field with machine learning methods}, volume = {983}, year = {2025}, }
• (2025). Mechanical torque disruption of dust grains induced by supernova shock waves. ApJ, 983(2), 172. (www)

  @article{ , abstract = {The feedback from massive stars drives the evolution of interstellar dust grains by altering their physical properties via a number of radiative and mechanical processes. Through these interactions, interstellar grains can achieve high rotational velocities due to unbalanced torques, potentially leading to their disruption. Mechanical torque disruption (METD) occurs when gas–grain collisions, induced by the passage of shocks, spin grains to critical rotational velocities. This study aims to investigate the effects of stochastic METD on both preexistent and supernova-condensed dust grains located within wind-blown bubbles. The impact of METD on supernova-condensed dust and dust grains in wind-blown bubbles is investigated through postprocessing of three-dimensional hydrodynamical simulation outputs. The associated timescale is then compared to those of kinetic sputtering and grain shattering. Before the supernova explosion, dust grain disruption timescales within wind-driven bubbles are on the order of millions of years due to the low-density environment. The timescales for METD are longer than those for kinetic sputtering and comparable to those of grain shattering, primarily due to the high grain drift velocities typical of these regions.}, archive = {J_ApJ}, author = {Sergio Martínez-González}, doi = {10.3847/1538-4357/adbe70}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {172}, shortjournal = {The Astrophys. J.}, title = {Mechanical torque disruption of dust grains induced by supernova shock waves}, volume = {983}, year = {2025}, }
• (2025). Observations of temporal variations in the 5303 Å emission line during a coronal mass ejection without any associated solar flare. ApJ, 983(2), 171. (www)

  @article{ , abstract = {Reports using total solar eclipse data indicate that the 5303 Å emission line is a promising tool for observing the thermodynamic changes due to coronal mass ejections (CMEs) close to the Sun. The Visible Emission Line Coronagraph (VELC) on board ADITYA-L1, the recently launched first Indian space solar mission, has now provided an opportunity to regularly observe the solar corona in the 5303 Å emission line. We present the first long-duration temporal observations of activity associated with a flareless CME from an active region at the west limb of the Sun, with the VELC. The observations were in the sit-and-stare mode for ≈7 hr. Our analysis shows a steady increase in the intensity of the line by ≈57%, followed by a gradual decrease to the initial level. The width of the line also showed changes, but opposite to that in the intensity. The width slowly decreased from 0.97 ± 0.01 Å to 0.87 ± 0.01 Å and then increased back. The change is ≈10%. The effective temperatures corresponding to each of the above two widths are 3.39 ± 0.1 × 10 6 K and 2.74 ± 0.1 × 10 6 K, respectively. The Doppler velocity changed gradually from 0 ± 0.5 km s −1 to −3 ± 0.5 km s −1 during the abovementioned intensity increase phase. It slowly reverted to 0 ± 0.5 km s −1 when the intensity decreased.}, archive = {J_ApJ}, author = {V. Muthu Priyal and R. Ramesh and Jagdev Singh and K. Sasikumar Raja}, doi = {10.3847/1538-4357/adbe73}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {171}, shortjournal = {The Astrophys. J.}, title = {Observations of temporal variations in the 5303 Å emission line during a coronal mass ejection without any associated solar flare}, volume = {983}, year = {2025}, }
• (2025). Potential contribution of young pulsar wind nebulae to galactic high-energy neutrino emission. ApJ, 983(2), 170. (www)

  @article{ , abstract = {Pulsar wind nebulae (PWNe), especially the young ones, are among the most energetic astrophysical sources in the Galaxy. It is usually believed that the spin-down energy injected from the pulsars is converted into magnetic field and relativistic electrons, but the possible presence of proton acceleration inside PWNe cannot be ruled out. Previous works have estimated the neutrino emission from PWNe using various source catalogs measured in gamma rays. However, some sources may be unresolved due to the limited sensitivity of TeV gamma-ray observations, while part of the unidentified sources may be related to off-beam pulsars. Here, we estimate the potential neutrino emission from a synthetic population of PWNe in the Galaxy with a focus on the ones that are still in the free expansion phase. In the calculation, we model the temporal evolution of the free-expanding PWNe and consider the transport of protons inside the PWNe. The Crab Nebula is treated as a standard template for young PWNe to evaluate some model parameters, such as the energy conversion fraction of relativistic protons and the target gas density for the hadronic process, which are relevant to neutrino production. In the optimistic case, the neutrino flux from the simulated young PWNe may constitute to 5% of the measured flux by IceCube around 100 TeV. At higher energy around 1 PeV, the neutrino emission from the population highly depends on the injection spectral shape, and also on the emission of the nearby prominent sources.}, archive = {J_ApJ}, author = {Xuan-Han Liang and Xiao-Bin Chen and Ben Li and Ruo-Yu Liu and Xiang-Yu Wang}, doi = {10.3847/1538-4357/adbe77}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {170}, shortjournal = {The Astrophys. J.}, title = {Potential contribution of young pulsar wind nebulae to galactic high-energy neutrino emission}, volume = {983}, year = {2025}, }
• (2025). Multifrequency very long baseline interferometry study of emission and absorption in the two-sided jets of NGC 3998. ApJ, 983(2), 169. (www)

  @article{ , abstract = {We present the multifrequency, multi-epoch very long baseline interferometry (VLBI) study of the two-sided jets in the low-luminosity active galactic nucleus NGC 3998, where physical properties of the jets on parsec scales remain poorly understood. Using Very Long Baseline Array data observed at 1.4, 1.7, 2.3, and 5 GHz, we detect symmetric twin jets aligned along the north–south direction, with a total extent of ∼5.3 pc. Notably, the position angle of the parsec-scale jets differs by 26°–30° from that of the kiloparsec-scale jets, suggesting the possibility of jet precession. Based on the frequency-dependent core shift and north/south jet brightness ratio, we identify the northern jet as the approaching jet and the southern jet as the counterjet. Measurements of the radial intensity profile on both sides indicate a change in the counterjet emission from rapid fading to a slower decline at 1.4, 1.7, and 2.3 GHz. Spectral analysis shows that the approaching jet exhibits an optically thin spectrum, while the counterjet is dominated by an optically thick, inverted spectrum. These findings tentatively suggest free–free absorption in NGC 3998, which should be verified in future studies. Finally, our observations also reveal a flat-spectrum VLBI core, showing significant radio variability that is likely linked to a jet ejection event.}, archive = {J_ApJ}, author = {Xi Yan and Lang Cui and Luis C. Ho}, doi = {10.3847/1538-4357/adc003}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {169}, shortjournal = {The Astrophys. J.}, title = {Multifrequency very long baseline interferometry study of emission and absorption in the two-sided jets of NGC 3998}, volume = {983}, year = {2025}, }
• (2025). Polarized signatures of the earth through time: An outlook for the habitable worlds observatory. ApJ, 983(2), 168. (www)

  @article{ , abstract = {The search for life beyond the solar system remains a primary goal of current and near-future missions, including NASA's upcoming Habitable Worlds Observatory (HWO). However, research into determining the habitability of terrestrial exoplanets has been primarily focused on comparisons to modern-day Earth. Additionally, current characterization strategies focus on the unpolarized flux from these worlds, taking into account only a fraction of the informational content of the reflected light. Better understanding the changes in the reflected-light spectrum of the Earth throughout its evolution, as well as analyzing its polarization, will be crucial for mapping its habitability and providing comparison templates to potentially habitable exoplanets. Here we present spectropolarimetric models of the reflected light from the Earth at six epochs across all four geologic eons. We find that the changing surface albedos and atmospheric gas concentrations across the different epochs allow the habitable and nonhabitable scenarios to be distinguished, and diagnostic features of clouds and hazes are more noticeable in the polarized signals. We also discuss how using Mie scattering for naturally nonspherical particles, which is a common simplification for exoplanet modeling, affects the resulting planetary signals. Finally, our results suggest that pushing the HWO planet-to-star flux contrast limit down to 1 × 10 −13 could allow for the characterization in both unpolarized and polarized light of an Earth-like planet at any stage in its history.}, archive = {J_ApJ}, author = {Kenneth E. Goodis Gordon and Theodora Karalidi and Kimberly M. Bott and Nicholas F. Wogan and Giada N. Arney and Mary N. Parenteau and Tiffany Kataria and Victoria S. Meadows}, doi = {10.3847/1538-4357/adc09c}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {168}, shortjournal = {The Astrophys. J.}, title = {Polarized signatures of the earth through time: An outlook for the habitable worlds observatory}, volume = {983}, year = {2025}, }
• (2025). Polar circumtriple planets and disks around misaligned hierarchical triple stars. ApJ, 983(2), 167. (www)

  @article{ , abstract = {Observations of hierarchical triple-star systems show that misalignments are common both between the angular momentum vector of the inner binary and the outer companion orbit, and between the outer binary orbit and a circumtriple gas disk. With analytic methods and n -body simulations, we explore the dynamics of circumtriple orbits around a misaligned hierarchical triple star. Circumtriple test-particle orbits nodally precess either about the outer binary angular momentum vector (circulating orbits) or about a stationary inclination that depends upon the binary properties (librating orbits). For a coplanar (or retrograde coplanar) triple star, the apsidal precession rate is maximal and the critical orbital radius outside of which all orbits are circulating is minimal. Polar alignment of a circumtriple gas disk requires nodal libration, and therefore it can be more likely if there is a large misalignment between the inner and outer binary orbits. There are two values of the mutual misalignment, i c and 180° − i c , for which the apsidal precession rate of the triple star is zero and polar alignment is possible at all orbital radii. For a circular inner binary orbit i c = 55°, and it changes with the eccentricity of the inner binary while being insensitive to other triple-star parameters.}, archive = {J_ApJ}, author = {Stephen Lepp and Rebecca G. Martin and Stephen H. Lubow}, doi = {10.3847/1538-4357/adc111}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {167}, shortjournal = {The Astrophys. J.}, title = {Polar circumtriple planets and disks around misaligned hierarchical triple stars}, volume = {983}, year = {2025}, }
• (2025). Recovering cosmic structure with a simple physical constraint. ApJ, 983(2), 166. (www)

  @article{ , abstract = {Radio observation of the large-scale structure (LSS) of our Universe faces major challenges from foreground contamination, which is many orders of magnitude stronger than the cosmic signal. While other foreground removal techniques struggle with complex systematics, methods like foreground avoidance emerge as effective alternatives. However, this approach inevitably results in the loss of Fourier modes and a reduction in cosmological constraints. We present a novel method that, by enforcing the non-negativity of the observed field in real space, allows us to recover some of the lost information, particularly phase angles. We demonstrate that the effectiveness of this straightforward yet powerful technique arises from the mode mixing from the nonlinear evolution of LSS. Since the non-negativity is ensured by mass conservation—one of the key principles of the cosmic dynamics— we can restore the lost modes without explicitly expressing the exact form of the mode mixing. Unlike previous methods, our approach utilizes information from highly nonlinear scales and has the potential to revolutionize the analysis of radio observational data in cosmology. Crucially, we demonstrate that in long-baseline interferometric observations, such as those from the Square Kilometre Array, it is still possible to recover the baryonic acoustic oscillation signature despite not directly covering the relevant scales. This opens up potential future survey designs for cosmological detection.}, archive = {J_ApJ}, author = {Tian-Cheng Luan and Xin Wang and Jiacheng Ding and Qian Li and Xiao-Dong Li and Weishan Zhu}, doi = {10.3847/1538-4357/adc1c6}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {166}, shortjournal = {The Astrophys. J.}, title = {Recovering cosmic structure with a simple physical constraint}, volume = {983}, year = {2025}, }
• (2025). Evolution of the M∗–MBH relation from z ∼ 6 to the present epoch. ApJ, 983(2), 165. (www)

  @article{ , abstract = {The ratio between the stellar mass of a galaxy, M * , and that of its central supermassive black hole (SMBH), M • , the "Magorrian" relationship, traces their coevolution. JWST observations have suggested significant evolution in M • / M * relative to local scaling relationships both in low-mass galaxies and in quasars at z ≥ 4. We test this possibility by (1) determining the preferred M • / M * scaling relation among those proposed locally, and (2) providing uniform estimates of host galaxy stellar mass. These steps reduce the prominence of the reported evolution. We then apply Monte Carlo simulations to account for observational biases. We still find a significant increase over the local scaling relation in M • / M * for z ≥ 4 SMBHs in very low-mass galaxies ( \mathrm{log}({M}_{* }/{M}_{\odot })\lt 10 ). However, similarly high values of M • / M * are also found in low-mass galaxies at z ∼ 0.5–3, which may be common at cosmic noon. Nonetheless, galaxies with similar behavior are rare locally and not accounted for in the local scaling relations. In contrast, z ∼ 6 quasars can have M • / M * well above the value given by the local relation, but they can be explained as extreme cases still within the scaling relation for their higher-mass host galaxies. Black holes in some of them and in the low-mass systems may be undergoing episodes of very high accretion that result in high M • / M * but that will be followed by quiescent periods when growth of the host drives the systems toward more typical M • / M * values.}, archive = {J_ApJ}, author = {Yang Sun and George H. Rieke and Jianwei Lyu and Meredith A. Stone and Zhiyuan Ji and Pierluigi Rinaldi and Christopher N. A. Willmer and Yongda Zhu}, doi = {10.3847/1538-4357/adc250}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {165}, shortjournal = {The Astrophys. J.}, title = {Evolution of the M∗–MBH relation from z ∼ 6 to the present epoch}, volume = {983}, year = {2025}, }
• (2025). New tests on lorentz invariance violation using energy-resolved polarimetry of gamma-ray bursts. ApJ, 983(2), 164. (www)

  @article{ , abstract = {One of the manifestations of Lorentz invariance violation (LIV) is vacuum birefringence, which leads to an energy-dependent rotation of the polarization plane of linearly polarized photons arising from an astrophysical source. Here we use the energy-resolved polarization measurements in the prompt gamma-ray emission of five bright gamma-ray bursts (GRBs) to constrain this vacuum birefringent effect. Our results show that at the 95% confidence level, the birefringent parameter η characterizing the broken degree of Lorentz invariance can be constrained to be | \eta | \lt { \mathcal O }(1{0}^{-15}-1{0}^{-16}) , which represents an improvement of at least 8 orders of magnitude over existing limits from multiband optical polarization observations. Moreover, our constraints are competitive with previous best bounds from the single gamma-ray polarimetry of other GRBs. We emphasize that, thanks to the adoption of the energy-resolved polarimetric data set, our results on η are statistically more robust. Future polarization measurements of GRBs at higher energies and larger distances would further improve LIV limits through the birefringent effect.}, archive = {J_ApJ}, author = {Jun-Jie Wei}, doi = {10.3847/1538-4357/adc4e1}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {164}, shortjournal = {The Astrophys. J.}, title = {New tests on lorentz invariance violation using energy-resolved polarimetry of gamma-ray bursts}, volume = {983}, year = {2025}, }
• (2025). Accretion bursts in young intermediate-mass stars make planet formation challenging. ApJ, 983(2), 163. (www)

  @article{ , abstract = {We investigate the occurrence of accretion bursts, dust accumulation, and the prospects for planetesimal formation in a gravitationally unstable magnetized protoplanetary disk (PPD) with globally suppressed but episodically triggered magnetorotational instability (MRI), particularly in young intermediate-mass stars (YIMSs) but with a brief comparison to low-mass counterparts. We use numerical magnetohydrodynamics simulations in the thin-disk limit (the Formation and Evolution Of a Star And its circumstellar Disk, or FEOSAD, code) to model the formation and long-term evolution of a gravitationally unstable magnetized PPD, including dust dynamics and growth, since the collapse of a massive slowly rotating prestellar cloud core. Massive gas concentrations and dust rings form within the inner disk region owing to the radially varying efficiency of mass transport by gravitational instability (GI). These rings are initially susceptible to streaming instability (SI). However, gradual warming of the dust rings thanks to high opacity and GI-induced influx of matter increases the gas temperature above a threshold for the MRI to develop via thermal ionization of alkaline metals. The ensuing MRI bursts destroy the dust rings, making planetesimal formation via SI problematic. In the later evolution phase, when the burst activity starts to diminish, SI becomes inefficient because of growing dust drift velocity and a more extended inner dead zone, both acting to reduce the dust concentration below the threshold for the SI to develop. Low-mass objects appear to be less affected by these adverse effects. Our results suggest that disks around YIMSs may be challenging environments for planetesimal formation via SI. This may explain the dearth of planets around stars with M * > 3.0 M ⊙ .}, archive = {J_ApJ}, author = {Indrani Das and Eduard Vorobyov and Shantanu Basu}, doi = {10.3847/1538-4357/adb8ee}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {163}, shortjournal = {The Astrophys. J.}, title = {Accretion bursts in young intermediate-mass stars make planet formation challenging}, volume = {983}, year = {2025}, }
• (2025). From young massive clusters to old globular clusters: Density profile evolution and intermediate-mass black hole formation. ApJ, 983(2), 162. (www)

  @article{ , abstract = {The surface brightness profiles of globular clusters are conventionally described with the well-known King profile. However, observations of young massive clusters (YMCs) in the local Universe suggest that they are better fit by simple models with flat central cores and simple power-law densities in their outer regions (such as the Elson-Fall-Freeman, or EFF, profile). Depending on their initial central density, YMCs may also facilitate large numbers of stellar collisions, potentially creating very massive stars that will directly collapse into intermediate-mass black holes (IMBHs). Using Monte Carlo N -body models of YMCs, we show that EFF-profile clusters transform to Wilson or King profiles through natural dynamical evolution, but that their final W 0 parameters do not strongly correlate to their initial concentrations. In the densest YMCs, runaway stellar mergers can produce stars that collapse into IMBHs, with their final masses depending on the treatment of the giant star envelopes during collisions. If a common-envelope prescription is assumed, where the envelope is partially or entirely lost, stars form with masses up to 824 M ⊙ , collapsing into IMBHs of 232 M ⊙ . Alternatively, if no mass loss is assumed, stars as massive as 4000 M ⊙ can form, collapsing into IMBHs of ∼4000 M ⊙ . In doing so, these runaway collisions also deplete the clusters of their primordial massive stars, reducing the number of stellar-mass BHs by as much as ∼40%. This depletion will accelerate the core collapse, suggesting that the process of IMBH formation itself may produce the high densities observed in some core-collapsed clusters.}, archive = {J_ApJ}, author = {Kuldeep Sharma and Carl L. Rodriguez}, doi = {10.3847/1538-4357/adbbdf}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {162}, shortjournal = {The Astrophys. J.}, title = {From young massive clusters to old globular clusters: Density profile evolution and intermediate-mass black hole formation}, volume = {983}, year = {2025}, }
• (2025). Chicago–Carnegie hubble program: A multiwavelength search for the effects of metallicity on the cepheid distance scale. i. empirical evidence. ApJ, 983(2), 161. (www)

  @article{ , abstract = {Understanding the effects of metallicity on the multiwavelength properties of Cepheids is of continuing importance for their effective use as extragalactic distance indicators and an accurate measure of the Hubble constant, H 0 . Quantifying the magnitude, and even the sign, of a metallicity effect, at one or more wavelengths, has been and continues to be challenging, and has not yet converged. Here we present the results of a multipronged investigation looking for empirical evidence of correlations linking the metallicities of Cepheids to the zero-point of the their multiwavelength period–luminosity relations. The empirical evidence leads to a self-consistent conclusion based on six tests, across many galaxies and in up to nine different bandpasses, from the optical to the mid-infrared. The major result is that for classical Cepheids, in none of the cases examined is there a metallicity effect, of any statistical significance, detected at any of the wavelengths examined. However, theoretical models of stellar atmospheres clearly show that metallicity will impact each of the bandpasses differently: the level of this effect is largest in the ultraviolet (where line blanketing is most intense), reversing sign in the optical (due to flux redistribution from the UV), and then asymptotically falling back to zero from the red to the far infrared. Close examination of these models reveals infrared regions in Cepheid spectral energy distributions that allow for the simultaneous correction for extinction and metallicity differences by the judicious combination of infrared filters alone, one centered at 1.2 μ m and the other at 3.6 μ m. Both of these bands can be simultaneously observed in single exposures using the dual-channel imager NIRCam on JWST.}, archive = {J_ApJ}, author = {Barry F. Madore and Wendy L. Freedman}, doi = {10.3847/1538-4357/adbd3d}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {161}, shortjournal = {The Astrophys. J.}, title = {Chicago–Carnegie hubble program: A multiwavelength search for the effects of metallicity on the cepheid distance scale. i. empirical evidence}, volume = {983}, year = {2025}, }
• (2025). Evidence for a link between turbulence and the generation of ion cyclotron waves via the helicity barrier effect in the solar wind. ApJ, 983(2), 160. (www)

  @article{ , abstract = {The dissipation and heating of collisionless plasma in the inner heliosphere is a significant unresolved problem in space physics. The helicity barrier theory suggests a possible mechanism for these processes, but it requires validation through analysis of spacecraft data. We assess the validity of the parameter regime associated with the helicity barrier in the solar wind over a range of heliocentric distances using Parker Solar Probe and Solar Orbiter. We use the Politano–Pouquet law to estimate the energy and cross helicity cascade rates in the solar wind and compare the values to radial distance, the polarization, and prevalence of ion cyclotron waves. We find that the amplitude and prevalence of left-hand-polarized waves in the solar wind is directly correlated with the total energy and the cross-helicity cascade rate of the turbulence. Our measurements are consistent with the helicity barrier being active in all solar wind intervals that we study, and we demonstrate the uncertainty in calculating energy and the cross-helicity cascade rates in this study.}, archive = {J_ApJ}, author = {Utsav Panchal and Robert T. Wicks and Julia E. Stawarz}, doi = {10.3847/1538-4357/adbfff}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {160}, shortjournal = {The Astrophys. J.}, title = {Evidence for a link between turbulence and the generation of ion cyclotron waves via the helicity barrier effect in the solar wind}, volume = {983}, year = {2025}, }
• (2025). VLASS tidal disruption events with optical flares. II. discovery of two TDEs with intermediate width balmer emission lines and connections to the ambiguous extreme coronal line emitters. ApJ, 983(2), 159. (www)

  @article{ , abstract = {The multiwavelength properties of radio-emitting tidal disruption events (TDEs) are poorly understood. In a previous paper, we presented the first sample of radio-selected, optically detected TDEs, which included two events (VT J1008 and VT J2012) associated with late-time (∼2 yr post-optical flare) intermediate width emission lines that are largely unprecedented from TDEs. In this paper, we investigate these two events in detail. The multiwavelength properties of these events are otherwise consistent with optically selected TDEs. They are hosted by green valley, E+A/Balmer dominated galaxies with low star formation rates and black holes masses M BH ≈ 10 5−6 M ⊙ . The optical flare shapes are fully consistent with those of optically selected TDEs, although they are slightly faint and cool at peak. The radio emission from both events is consistent with wide-angle, nonrelativistic outflows with L R (GHz) ∼ 10 38 erg s −1 . Balmer and helium emission lines are detected from both events with FWHM ∼700 km s −1 and asymmetric line profiles. VT J1008 additionally shows coronal line emission with a similar width. The lines from VT J2012 are redshifted by ∼700 km s −1 relative to the host galaxy. We show that these events share many characteristics in common with the ambiguous class of extreme coronal line emitters. We argue that the lines are likely associated with a radiative shock or dense, photoionized clumps of outflowing gas in the circumnuclear medium.}, archive = {J_ApJ}, author = {Jean J. Somalwar and Vikram Ravi and Wenbin Lu}, doi = {10.3847/1538-4357/adc002}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {159}, shortjournal = {The Astrophys. J.}, title = {VLASS tidal disruption events with optical flares. II. discovery of two TDEs with intermediate width balmer emission lines and connections to the ambiguous extreme coronal line emitters}, volume = {983}, year = {2025}, }
• (2025). Quantifying systematic uncertainties in white dwarf cooling age determinations. ApJ, 983(2), 158. (www)

  @article{ , abstract = {Cooling ages of white dwarfs are routinely determined by mapping effective temperatures and masses to ages using evolutionary models. Typically, the reported uncertainties on cooling ages only consider the error propagation of the uncertainties on the spectroscopically or photometrically determined T eff and mass. However, cooling models are themselves uncertain, given their dependence on many poorly constrained inputs. This paper estimates these systematic model uncertainties. We use MESA to generate cooling sequences of 0.5–1.0 M ⊙ hydrogen-atmosphere white dwarfs with carbon–oxygen cores under different assumptions regarding the chemical stratification of their core, the thickness of their helium envelope, their hydrogen content, and the conductive opacities employed in the calculations. The parameter space explored is constrained by the range of values predicted by a variety of stellar evolution models and inferred from asteroseismological studies. For a 0.6 M ⊙ white dwarf, we find an uncertainty of 0.03 Gyr at 10,000 K (corresponding to a 5% relative uncertainty) and 0.8 Gyr at 4000 K (9%). This uncertainty is significant, as it is comparable to the age uncertainty obtained by propagating the measurement errors on T eff and mass for a typical white dwarf. We also separately consider the potential impact of 22 Ne shell distillation, which plausibly leads to an additional uncertainty of ∼1 Gyr for crystallized white dwarfs. We provide a table of our simulation results that can be used to evaluate the systematic model uncertainty based on a white dwarf's T eff and mass. We encourage its use in all future studies where white dwarf cooling ages are measured.}, archive = {J_ApJ}, author = {Praneet Pathak and Simon Blouin and Falk Herwig}, doi = {10.3847/1538-4357/adc10f}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {158}, shortjournal = {The Astrophys. J.}, title = {Quantifying systematic uncertainties in white dwarf cooling age determinations}, volume = {983}, year = {2025}, }
• (2025). Spin and obliquity evolution of hot jupiter hosts from resonance locks. ApJ, 983(2), 157. (www)

  @article{ , abstract = {When a hot Jupiter orbits a star whose effective temperature exceeds ∼6100 K, its orbit normal tends to be misaligned with the stellar spin axis. Cooler stars typically have smaller obliquities, which may have been damped by hot Jupiters in resonance lock with axisymmetric stellar gravity modes (azimuthal number m = 0). Here we allow for resonance locks with nonaxisymmetric modes, which affect both stellar obliquity and spin frequency. Obliquities damp for all modes (−2 ≤ m ≤ 2). Stars spin-up for m > 0, and spin-down for m < 0. We carry out a population synthesis that assumes hot Jupiters form misaligned around both cool and hot stars, and subsequently lock onto modes whose m- values yield the highest mode energies for given starting obliquities. Core hydrogen burning enables hot Jupiters to torque low-mass stars, but not high-mass stars, into spin–orbit alignment. Resonance locking plus stellar spin-down from magnetic braking largely reproduces observed obliquities and stellar rotation rates and how they trend with stellar effective temperature and orbital separation. The possible suppression of resonance locking by nonlinear dissipation of gravity waves remains an outstanding issue.}, archive = {J_ApJ}, author = {J. J. Zanazzi and Eugene Chiang}, doi = {10.3847/1538-4357/adc114}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {157}, shortjournal = {The Astrophys. J.}, title = {Spin and obliquity evolution of hot jupiter hosts from resonance locks}, volume = {983}, year = {2025}, }
• (2025). Probing solar modulation of AMS-02 time-dependent d, 3He, and 4He fluxes with modified force-field approximation models. ApJ, 983(2), 156. (www)

  @article{ , abstract = {The AMS-02 experiment recently published time-dependent fluxes of deuterons (D) from 2011 May to 2021 April, divided into 33 periods of four Bartels rotations each. These temporal structures are associated with solar modulation. In this study, three modified force-field approximations (FFAs) are employed to examine the long-term behavior of cosmic-ray isotopes such as D, 3 He, and 4 He, as well as the ratios D/ 3 He and 3 He/ 4 He. The solar modulation potential is rigidity dependent for these modified FFA models. Due to the unknown local interstellar spectrum (LIS) for these isotopes, we utilize the non-LIS method for solar modulation. By fitting to the AMS-02 time-dependent fluxes, we derive the solar modulation parameters. Our findings prove the assumption in literature that all isotopes can be fitted using the same solar modulation parameters, and it is shown that the modified FFA models provide valid parameterization for solar modulation. Based on these, we forecast the daily fluxes of D, 3 He, and 4 He from 2011 to 2020.}, archive = {J_ApJ}, author = {Cheng-Rui Zhu and Mei-Juan Wang}, doi = {10.3847/1538-4357/adc12c}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {156}, shortjournal = {The Astrophys. J.}, title = {Probing solar modulation of AMS-02 time-dependent d, 3He, and 4He fluxes with modified force-field approximation models}, volume = {983}, year = {2025}, }
• (2025). Filamentary electron-beam heating in solar flares. ApJ, 983(2), 155. (www)

  @article{ , abstract = {Radiation-hydrodynamic simulations of the solar-flare chromospheric emission very often lead to an excess of the line intensities when compared to observations. Various studies suggest that the flare loops have a certain intrinsic, multithread internal structure, which is still not resolved by current telescopes. Taking this into account, we want to test and compare two different approaches for flare simulations. The first approach is the commonly used one, based on a continuous flux of nonthermal electrons heating the chromosphere for a rather long time. In the second approach, we consider the heating by short beam pulses consecutively within spatially unresolved filaments. Superposition of these short-duration pulses gives us the same electron-beam flux as in the first approach, but we are showing that the filamentary heating generates lower intensities in both the H α and Mg ii k lines, as expected.}, archive = {J_ApJ}, author = {Michalina Litwicka and Petr Heinzel and Jana Kašparová}, doi = {10.3847/1538-4357/adc393}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {155}, shortjournal = {The Astrophys. J.}, title = {Filamentary electron-beam heating in solar flares}, volume = {983}, year = {2025}, }
• (2025). JWST/MIRI detection of [Ne v] and [Ne vi] in m83: Evidence for the long sought-after active galactic nucleus?. ApJ, 983(2), 154. (www)

  @article{ , abstract = {We report the first detections of [Ne v] λ 14.3 μ m and [Ne vi ] λ 7.7 μ m at high confidence (S/N ≥ 6) in the nuclear region of the nearby spiral galaxy M83. Emission-line maps of these high-ionization lines show several compact structures. Specifically, the [Ne vi ] emission is located at 140 pc from the optical nucleus and appears as a point source of size ≲18 pc (FWHM ≲ 0 \mathop{.}\limits^{\unicode{x02033}} 8). We investigate the possible source of this extreme emission through comparison with photoionization models and ancillary data. We find that photoionization models of fast radiative shocks are able to reproduce the observed high-excitation emission-line fluxes only for the lowest preshock density available in the library, n = 0.01 cm −3 . Additionally, tailored active galactic nucleus (AGN) photoionization models assuming a two-zone structure are compatible with the observed high-ionization fluxes. Our simple AGN model shows that the emission at the location of the [Ne vi ] source can be the result of a cloud being ionized by the radiation cone of an AGN. We stress, however, that to definitively confirm an AGN as the main source of the observed emission, more complex modeling accounting for different geometries is required. Previously known as a purely starburst system, these new findings of the nuclear region of M83 will require a reassessment of its nature and of objects similar to it, particularly now that we have access to the unparalleled infrared sensitivity and spatial resolution of the James Webb Space Telescope.}, archive = {J_ApJ}, author = {Svea Hernandez and Linda J. Smith and Logan H. Jones and Aditya Togi and Marcio B. Meléndez and Valentina Abril-Melgarejo and Angela Adamo and Almudena Alonso Herrero and Tanio Díaz-Santos and Travis C. Fischer and Santiago García-Burillo and Alec S. Hirschauer and Leslie K. Hunt and Bethan James and Vianney Lebouteiller and Knox S. Long and Matilde Mingozzi and Lise Ramambason and Cristina Ramos Almeida}, doi = {10.3847/1538-4357/adba5d}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {154}, shortjournal = {The Astrophys. J.}, title = {JWST/MIRI detection of [Ne v] and [Ne vi] in m83: Evidence for the long sought-after active galactic nucleus?}, volume = {983}, year = {2025}, }
• (2025). Secret of longevity: Protoplanetary disks as a source of gas in debris disks. ApJ, 983(2), 153. (www)

  @article{ , abstract = {While protoplanetary disks (PPDs) are generally thought to disperse within several million years, recent observations have revealed gas in their older counterparts, debris disks. The origin of this gas remains uncertain, with one possibility being the unexpectedly long survival of PPDs (the primordial-origin scenario). To explore the plausibility of this scenario, we conduct 1D disk evolution simulations, varying parameters like stellar mass, disk mass, turbulent stress, and the model of magnetohydrodynamic winds, while incorporating stellar evolution to account for time-varying photoevaporation rates. Our focus is on disks where small grains are depleted, as these are potentially long lived due to reduced far-ultraviolet photoevaporation. Our results show that gas in these disks can survive beyond 10 Myr regardless of the stellar mass, provided they are initially massive ( M disk ≈ 0.1 M * ) with relatively weak turbulent stress ( α ≪ 10 −2 ). The longest lifetimes are consistently found for M * = 2 M ⊙ across a wide parameter space, with gas typically persisting at ∼10–10 3 au. Roughly estimated CO masses for these disks fall within the observed range for the most massive gas-rich debris disks around early A stars. These alignments support the plausibility of the primordial-origin scenario. Additionally, our model predicts that accretion persists for as long as the disk survives, which could explain the accretion signatures detected in old disks hosted by low-mass stars, including Peter Pan disks. Our finding also suggests that ongoing accretion may exist in gas-rich debris disks. Thus, searching for accretion signatures could be a key to determining the origins of gas in debris disks.}, archive = {J_ApJ}, author = {Wataru Ooyama and Riouhei Nakatani and Takashi Hosokawa and Hiroto Mitani and Neal J. Turner}, doi = {10.3847/1538-4357/adbbb8}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {153}, shortjournal = {The Astrophys. J.}, title = {Secret of longevity: Protoplanetary disks as a source of gas in debris disks}, volume = {983}, year = {2025}, }
• (2025). BEACON: JWST NIRCam pure-parallel imaging survey. i. survey design and initial results. ApJ, 983(2), 152. (www)

  @article{ , abstract = {We introduce the Bias-free Extragalactic Analysis for Cosmic Origins with NIRCam (BEACON) survey, a JWST Cycle 2 program allocated up to 600 pure-parallel hours of observations. BEACON explores high-latitude areas of the sky with JWST/NIRCam over  ∼100 independent sight lines, totaling ∼0.3 deg 2 , reaching a median F444W depth of  ≈28.2 AB mag (5 σ ). Based on existing JWST observations in legacy fields, we estimate that BEACON will photometrically identify 25–150 galaxies at z > 10 and 500–1000 at z ∼ 7–10 uniquely enabled by an efficient multiple filter configuration spanning 0.9–5.0 μ m. The expected sample size of z > 10 galaxies will allow us to obtain robust number density estimates and to discriminate between different models of early star formation. In this paper, we present an overview of the survey design and initial results using the first 19 fields. We present 129 galaxy candidates at z ≳7 identified in those fields, including 11 galaxies at z ≳10 and several UV-luminous ( M UV < −21 mag) galaxies at z ∼ 8. The number densities of z < 13 galaxies inferred from the initial fields are overall consistent with those in the literature. Despite reaching a considerably large volume (∼10 5 Mpc 3 ), however, we find no galaxy candidates at z > 13, providing us with a complimentary insight into early galaxy evolution with minimal cosmic variance. We publish imaging and catalog data products for these initial fields. Upon survey completion, all BEACON data will be coherently processed and distributed to the community along with catalogs for redshift and other physical quantities.}, archive = {J_ApJ}, author = {Takahiro Morishita and Charlotte A. Mason and Kimi C. Kreilgaard and Michele Trenti and Tommaso Treu and Benedetta Vulcani and Yechi Zhang and Abdurro’uf and Anahita Alavi and Hakim Atek and Yannick Bahé and Maruša Bradač and Larry D. Bradley and Andrew J. Bunker and Dan Coe and James Colbert and Viola Gelli and Matthew J. Hayes and Tucker Jones and Tadayuki Kodama and Nicha Leethochawalit and Zhaoran Liu and Matthew A. Malkan and Vihang Mehta and Benjamin Metha and Andrew B. Newman and Marc Rafelski and Guido Roberts-Borsani and Michael J. Rutkowski and Claudia Scarlata and Massimo Stiavelli and Ryo A. Sutanto and Kosuke Takahashi and Harry I. Teplitz and Xin Wang}, doi = {10.3847/1538-4357/adbbdc}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {152}, shortjournal = {The Astrophys. J.}, title = {BEACON: JWST NIRCam pure-parallel imaging survey. i. survey design and initial results}, volume = {983}, year = {2025}, }
• (2025). The all-sky impact of the LMC on the milky way circumgalactic medium. ApJ, 983(2), 151. (www)

  @article{ , abstract = {The first infall of the LMC into the Milky Way (MW) represents a large and recent disruption to the MW circumgalactic medium (CGM). In this work, we use idealized, hydrodynamical simulations of an MW-like CGM embedded in a dark matter halo with an infalling LMC-like satellite initialized with its own CGM to understand how the encounter is shaping the global physical and kinematic properties of the MW CGM. First, we find that the LMC drives order-unity enhancements in MW CGM density, temperature, and pressure due to a { \mathcal M }\approx 2 shock from the supersonic CGM–CGM collision. The resulting shock front extends from the LMC to beyond ∼ R 200,MW , amplifying column densities, X-ray brightness, thermal Sunyaev–Zeldovich distortion, and potentially synchrotron emission from cosmic rays over large angular scales across the southern hemisphere. Second, the MW's reflex motion relative to its outer halo induces a dipole in CGM radial velocities, with v R ± 30–50 km s −1 at R > 50 kpc in the northern and southern hemispheres, respectively, consistent with measurements in the stellar halo. Finally, ram pressure strips most of the LMC's CGM, leaving ∼10 8−9 M ⊙ warm ionized gas along the past orbit of the LMC, moving at high radial and/or tangential velocities ∼50–100 kpc from the MW. Massive satellites like the LMC leave their mark on the CGM structure of their host galaxies, and signatures of such interactions may be observable in key all-sky tracers of the MW CGM and those of other massive galaxies.}, archive = {J_ApJ}, author = {Christopher Carr and Greg L. Bryan and Nicolás Garavito-Camargo and Gurtina Besla and David J. Setton and Kathryn V. Johnston and Kung-Yi Su}, doi = {10.3847/1538-4357/adbf1d}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {151}, shortjournal = {The Astrophys. J.}, title = {The all-sky impact of the LMC on the milky way circumgalactic medium}, volume = {983}, year = {2025}, }
• (2025). Spectroscopy of supernova remnants and candidates in m31. ApJ, 983(2), 150. (www)

  @article{ , abstract = {With a star formation rate of order 0.4 M ⊙ yr −1 , M31 should have a significant population of supernova remnants (SNRs) and, in fact, 156 SNRs and SNR candidates have been suggested by J. H. Lee & M. G. Lee, by searching for nebulae with elevated [S ii ]/H α ratios in narrowband images. Here, we use a combination of low- and high-resolution optical spectroscopy obtained with Hectospec on the MMT to characterize 152 of these nebulae. Of these candidates, we find 93 nebulae that have [S ii ]/H α ratios that exceed 0.4, the traditional ratio used to separate SNRs from H ii regions, strongly suggesting that at least these objects are SNRs. Our high-resolution spectroscopy reveals 108 nebulae that have velocity widths in H α (full width at 20% peak flux) that exceed 50 km s −1 , significantly larger than found in H ii regions. There are 72 objects that satisfy both tests. Here, we discuss the spectroscopic characteristics of all of the objects in our sample, and the likelihood that other objects in the sample of J. H. Lee & M. G. Lee are also SNRs, and we briefly consider confirmation by X-ray, radio, and UV observations. We also discuss several new candidates that have been identified serendipitously in the course of examining a large amount of archival Hectospec data.}, archive = {J_ApJ}, author = {Nelson Caldwell and John C. Raymond and Knox S. Long and Myung Gyoon Lee}, doi = {10.3847/1538-4357/adbf98}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {150}, shortjournal = {The Astrophys. J.}, title = {Spectroscopy of supernova remnants and candidates in m31}, volume = {983}, year = {2025}, }
• (2025). Probing the hot gaseous halo of the low-mass disk galaxy NGC 7793 with eROSITA and chandra. ApJ, 983(2), 149. (www)

  @article{ , abstract = {Galaxy formation models predict that local galaxies are surrounded by hot X-ray-emitting halos, which are technically difficult to detect due to their extended and low surface brightness nature. Previous X-ray studies have mostly focused on disk galaxies more massive than the Milky Way, with essentially no consensus on the halo X-ray properties at the lower mass end. We utilize the early-released eROSITA and archival Chandra observations to analyze the diffuse X-ray emission of NGC 7793, a nearby spiral galaxy with an estimated stellar mass of only 3.2 × 10 9 M ⊙ . We find evidence for extraplanar hot gas emission from both the radial and vertical soft X-ray intensity profiles, which spreads up to a galactocentric distance of ∼6 kpc, nearly 30% more extended than its stellar disk. Analysis of the eROSITA spectra indicates that the hot gas can be characterized by a temperature of 0.1{8}_{-0.03}^{+0.02} keV, with 0.5–2 keV unabsorbed luminosity of 1.3 × 10 38 erg s −1 . We compare our results with the IllustrisTNG simulations and find overall consistence on the disk scale, whereas excessive emission at large radii is predicted by TNG50 . This work provides the latest detection of hot corona around a low-mass galaxy, putting new constraints on state-of-the-art cosmological simulations. We also verify the detectability of hot circumgalactic medium around even low-mass spirals with future high-resolution X-ray spectrometers such as the Hot Universe Baryon Surveyor.}, archive = {J_ApJ}, author = {Lin He and Zhiyuan Li and Meicun Hou and Min Du and Taotao Fang and Wei Cui}, doi = {10.3847/1538-4357/adc0a0}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {149}, shortjournal = {The Astrophys. J.}, title = {Probing the hot gaseous halo of the low-mass disk galaxy NGC 7793 with eROSITA and chandra}, volume = {983}, year = {2025}, }
• (2025). V1047 cen: The first z and-type outburst observed in the classical nova binary. ApJ, 983(2), 148. (www)

  @article{ , abstract = {In 2019, the classical nova V1047 Cen experienced an unusual outburst, the nature of which has not yet been clearly determined. In this paper, we show that the 2019 V1047 Cen outburst is of Z And-type—a type that is characteristic of and has so far been observed only in symbiotic binaries. We support our claim by modeling the near-ultraviolet to near-infrared spectral energy distribution, which revealed a close similarity between the fundamental parameters and the mass-loss rate of the burning white dwarf (WD) during the 2019 V1047 Cen outburst and those measured during Z And-type outbursts in symbiotic stars. All parameters are in good agreement with the theoretical prediction when the accretion rate exceeds the stable burning limit for WDs with masses ≲0.7 M ⊙ . Our analysis showed that after a nova explosion, the Z And-type outburst can occur not only in symbiotic binaries, but also in short-period cataclysmic variables, when the accretion-powered system changes to a nuclear-powered one as a consequence of the donor's reaction to the nova explosion. Such a development promotes the production of Type Ia supernovae.}, archive = {J_ApJ}, author = {Augustin Skopal and Natalia Shagatova}, doi = {10.3847/1538-4357/adc0f6}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {148}, shortjournal = {The Astrophys. J.}, title = {V1047 cen: The first z and-type outburst observed in the classical nova binary}, volume = {983}, year = {2025}, }
• (2025). Proper motion and natal kick in the galactic black hole X-ray binary AT2019wey. ApJ, 983(2), 147. (www)

  @article{ , abstract = {Understanding the formation mechanisms of stellar-mass black hole X-ray binaries (BHXBs) remains a fundamental challenge in astrophysics. The natal kick velocities imparted during black hole (BH) formation provide crucial constraints on these formation channels. In this work, we present a new-epoch very long baseline interferometry (VLBI) observation of the Galactic BHXB AT2019wey carried out in 2023. Combining with archival VLBI data from 2020, we successfully measure the proper motion of AT2019wey over a 3 yr timescale, namely, 0.78 ± 0.12 mas yr −1 in R.A. and −0.42 ± 0.07 mas yr −1 in decl. Employing the measured proper motion, we estimate its peculiar velocity and the potential kick velocity (PKV) through Monte Carlo simulations, incorporating uncertainties of its distance and radial velocity. The estimated PKV distributions and height above the Galactic plane suggest that AT2019wey's BH likely formed through a supernova explosion rather than direct collapse.}, archive = {J_ApJ}, author = {Lang Cui and Pengfei Jiang and Tao An and Hongmin Cao and Ning Chang and Giulia Migliori and Marcello Giroletti and Sándor Frey and Jun Yang and Krisztina É. Gabányi and Xiaoyu Hong and Wenda Zhang}, doi = {10.3847/1538-4357/adc0f7}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {147}, shortjournal = {The Astrophys. J.}, title = {Proper motion and natal kick in the galactic black hole X-ray binary AT2019wey}, volume = {983}, year = {2025}, }
• (2025). The relativistic outflow driven by the large-scale magnetic field from an accretion disk. ApJ, 983(2), 146. (www)

  @article{ , abstract = {Outflows/jets are ubiquitous in a wide range of astrophysical objects, yet the mechanisms responsible for their generation remain elusive. One hypothesis is that they are magnetically driven. Based on general relativistic MHD equations, we establish a formulation to describe the outflows driven by large-scale magnetic fields from the accretion disk in Schwarzschild spacetime. The outflow solution manifests as a contour level of a "Bernoulli" function, which is determined by ensuring that it passes through both the slow and fast magnetosonic points. This approach is a general relativistic extension to the classical treatment of X. Cao & H. C. Spruit. The initial plasma β that permits magnetically driven outflow solutions is constrained, with the slow magnetosonic point above the footpoint setting an upper limit ( β b ≲ 2) and the Alfvén point inside the light cylinder setting a lower limit ( β b ≳ 0.02). The higher the magnetization, the higher the temperature allowed, leading to relativistic outflows/jets. We investigate the relativistic outflows/jets of several typical objects, such as active galactic nuclei, X-ray binaries, and gamma-ray bursts. The results indicate that all of these phenomena require strongly magnetized, high-temperature outflows as initial conditions, suggesting a potential association between the production of relativistic outflows/jets and corona-like structures.}, archive = {J_ApJ}, author = {Wei Xie and Wei-Hua Lei}, doi = {10.3847/1538-4357/adc100}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {146}, shortjournal = {The Astrophys. J.}, title = {The relativistic outflow driven by the large-scale magnetic field from an accretion disk}, volume = {983}, year = {2025}, }
• (2025). A demarcation criterion for hydrogen burning of millinovae. ApJ, 983(2), 145. (www)

  @article{ , abstract = {Millinovae are a new class of transient supersoft X-ray sources with no clear signature of mass ejection. They show similar triangle shapes of V / I band light curves with 1000 times fainter peaks than typical classical novae. Maccarone et al. regarded the prototype millinova, ASASSN-16oh, as a dwarf nova and interpreted the supersoft X-rays to originate from an accretion belt on a white dwarf (WD). Kato et al. proposed a nova model induced by high-rate mass accretion during a dwarf nova outburst; the X-rays originate from the photosphere of a hydrogen-burning hot WD, whereas the V / I band photons are from the irradiated accretion disk. Because each peak brightness differs largely from millinova to millinova, we suspect that not all millinova candidates host a hydrogen-burning WD. Based on the light-curve analysis of the classical nova KT Eri that has a bright disk, we find that the disk is more than 2 magnitudes brighter when the disk is irradiated by the hydrogen-burning WD than when not irradiated. We present the demarcation criterion for hydrogen burning to be {I}_{{\rm{q}}}-{I}_{{\rm{\max }}}\gt 2.2 , where I q and {I}_{{\rm{\max }}} are the I magnitudes in quiescence and at maximum light, respectively. Among many candidates, this requirement is satisfied with the two millinovae in which soft X-rays were detected.}, archive = {J_ApJ}, author = {Izumi Hachisu and Mariko Kato}, doi = {10.3847/1538-4357/adc107}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {145}, shortjournal = {The Astrophys. J.}, title = {A demarcation criterion for hydrogen burning of millinovae}, volume = {983}, year = {2025}, }
• (2025). Unveiling the dynamics and genesis of small-scale fine-structure loops in the lower solar atmosphere. ApJ, 983(2), 144. (www)

  @article{ , abstract = {Recent high-resolution solar observations have unveiled the presence of small-scale loop-like structures in the lower solar atmosphere, often referred to as unresolved fine structures, low-lying loops, and miniature hot loops. These structures undergo rapid changes within minutes, and their formation mechanism has remained elusive. In this study, we conducted a comprehensive analysis of two small loops utilizing data from the Interface Region Imaging Spectrograph (IRIS), the Goode Solar Telescope (GST) at Big Bear Solar Observatory, and the Atmospheric Imaging Assembly and the Helioseismic Magnetic Imager on board the Solar Dynamics Observatory, aiming to elucidate the underlying process behind their formation. The GST observations revealed that these loops, with lengths of ∼3.5 Mm and heights of ∼1 Mm, manifest as bright emission structures in H α wing images, particularly prominent in the red wing. IRIS observations showcased these loops in 1330 Å slit-jaw images, with transition region (TR) and chromospheric line spectra exhibiting significant enhancement and broadening above the loops, indicative of plasmoid-mediated reconnection during their formation. Additionally, we observed upward-erupting jets above these loops across various passbands. Furthermore, differential emission measurement analysis reveals an enhanced emission measure at the location of these loops, suggesting the presence of plasma exceeding 1 MK. Based on our observations, we propose that these loops and associated jets align with the minifilament eruption model. Our findings suggest a unified mechanism governing the formation of small-scale loops and jets akin to larger-scale X-ray jets.}, archive = {J_ApJ}, author = {Annu Bura and Tanmoy Samanta and Alphonse C. Sterling and Yajie Chen and Jayant Joshi and Vasyl Yurchyshyn and Ronald L. Moore}, doi = {10.3847/1538-4357/adc109}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {144}, shortjournal = {The Astrophys. J.}, title = {Unveiling the dynamics and genesis of small-scale fine-structure loops in the lower solar atmosphere}, volume = {983}, year = {2025}, }
• (2025). Minifilament eruptions as the last straw to break the equilibrium of a giant solar filament. ApJ, 983(2), 143. (www)

  @article{ , abstract = {Filament eruptions are magnetically driven violent explosions commonly observed on the Sun and late-type stars, sometimes leading to monster coronal mass ejections that directly affect the nearby planets' environments. More than a century of research on solar filaments suggests that the slow evolution of photospheric magnetic fields plays a decisive role in initiating filament eruptions, but the underlying mechanism remains unclear. Using high-resolution observations from the Chinese H α Solar Explorer, the Solar Upper Transition Region Imager, and the Solar Dynamics Observatory, we present direct evidence that a giant solar filament eruption is triggered by a series of minifilament eruptions occurring beneath it. These minifilaments, which are homologous to the giant filament but on a smaller tempo-spatial scale, sequently form and erupt due to extremely weak mutual flux disappearance of opposite-polarity photospheric magnetic fields. Through multifold magnetic interactions, these erupting minifilaments act as the last straw to break the force balance of the overlying giant filament and initiate its ultimate eruption. The results unveil a possible novel pathway for small-scale magnetic activities near the stellar surface to initiate spectacular filament eruptions, and provide new insight into the magnetic coupling of filament eruptions across different tempo-spatial scales.}, archive = {J_ApJ}, author = {Hechao Chen and Hui Tian and Quanhao Zhang and Chuan Li and Chun Xia and Xianyong Bai and Zhenyong Hou and Kaifan Ji and Yuanyong Deng and Xiao Yang and Ziyao Hu}, doi = {10.3847/1538-4357/adc12a}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {143}, shortjournal = {The Astrophys. J.}, title = {Minifilament eruptions as the last straw to break the equilibrium of a giant solar filament}, volume = {983}, year = {2025}, }
• (2025). First measurement of 87Rb(α, xn) cross sections at weak r-process energies in supernova ν-driven ejecta to investigate elemental abundances in low-metallicity stars. ApJ, 983(2), 142. (www)

  @article{ , abstract = {Observed abundances of Z ∼ 40 elements in metal-poor stars vary from star to star, indicating that the rapid and slow neutron capture processes may not contribute alone to the synthesis of elements beyond iron. The weak r -process was proposed to produce Z ∼ 40 elements in a subset of old stars. Thought to occur in the ν -driven ejecta of a core-collapse supernova, ( α , xn ) reactions would drive the nuclear flow toward heavier masses at T = 2−5 GK. However, current comparisons between modeled and observed yields do not bring satisfactory insights into the stellar environment, mainly due to the uncertainties of the nuclear physics inputs where the dispersion in a given reaction rate often exceeds 1 order of magnitude. Involved rates are calculated with the statistical model where the choice of an α -optical-model potential ( α OMP) leads to such a poor precision. The first experiment on 87 Rb( α , xn ) reactions at weak r -process energies is reported here. Total inclusive cross sections were assessed at E c.m. = 8.1−13 MeV (3.7−7.6 GK) with the active target MUlti-Sampling Ionization Chamber. With an N = 50 seed nucleus, the measured values agree with statistical model estimates using the α OMP Atomki-V2 . A reevaluated reaction rate was incorporated into new nucleosynthesis calculations, focusing on ν -driven ejecta conditions known to be sensitive to this specific rate. These conditions were found to fail to reproduce the lighter heavy element abundances in metal-poor stars.}, archive = {J_ApJ}, author = {C. Fougères and M. L. Avila and A. Psaltis and M. Anastasiou and S. Bae and L. Balliet and K. Bhatt and L. Dienis and H. Jayatissa and V. Karayonchev and P. Mohr and F. Montes and D. Neto and F. de Oliveira Santos and W.-J. Ong and K. E. Rehm and W. Reviol and D. Santiago-Gonzalez and N. Sensharma and R. S. Sidhu and I. A. Tolstukhin}, doi = {10.3847/1538-4357/adc253}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {142}, shortjournal = {The Astrophys. J.}, title = {First measurement of 87Rb(α, xn) cross sections at weak r-process energies in supernova ν-driven ejecta to investigate elemental abundances in low-metallicity stars}, volume = {983}, year = {2025}, }
• (2025). Redshift evolution of the X-ray and ultraviolet luminosity relation of quasars: Calibrated results from SNe ia. ApJ, 983(2), 141. (www)

  @article{ , abstract = {Quasars could serve as standard candles if the relation between their ultraviolet (UV) and X-ray luminosities can be accurately calibrated. Previously, we developed a model-independent method to calibrate quasar standard candles using the distance–redshift relation reconstructed from Type Ia supernovae (SNe Ia) at z < 2 using Gaussian process regression. Interestingly, we found that the calibrated quasar standard candle data set preferred a deviation from ΛCDM at redshifts above z > 2. One possible interpretation of these findings is that the calibration parameters of the quasar UV and X-ray luminosity relationship evolves with redshift. In order to test the redshift dependence of the quasar calibration in a model-independent manner, we divided the quasar sample whose redshift overlaps with the redshift coverage of Pantheon+ SNe Ia compilation into two subsamples: a low-redshift quasar subsample and a high-redshift quasar subsample. Assuming all the quasar samples are reliable, our results show that there is about a 4 σ inconsistency between the quasar parameters inferred from the subsamples without considering evolution. This inconsistency suggests the possibility of considering redshift evolution for the relationship between the quasars' UV and X-ray luminosities. We then test an explicit parameterization of the redshift evolution of the quasar calibration parameters via γ ( z ) = γ 0 + γ 1 (1 + z ) and β ( z ) = β 0 + β 1 (1 + z ). Combining this redshift-dependent calibration relationship with the distance–redshift relationship reconstructed from the Pantheon+ supernova compilation, we find the high-redshift subsample and low-redshift subsample become consistent at the 2 σ level, which means that the parameterized form of γ ( z ) and β ( z ) works well at describing the evolution of the quasar calibration parameters.}, archive = {J_ApJ}, author = {Xiaolei Li and Ryan E. Keeley and Arman Shafieloo}, doi = {10.3847/1538-4357/adc2fe}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {141}, shortjournal = {The Astrophys. J.}, title = {Redshift evolution of the X-ray and ultraviolet luminosity relation of quasars: Calibrated results from SNe ia}, volume = {983}, year = {2025}, }
• (2025). CY aquarii: A triple system with twin companions. ApJ, 983(2), 140. (www)

  @article{ , abstract = {In this study, we conducted a comprehensive analysis of the SX Phoenicis (SX Phe) type star CY Aquarii (CY Aqr). Our investigation included a detailed O − C analysis based on a 90 yr observational data set, augmented by 1367 newly determined times of maximum light. The O − C diagram reveals that (i) the primary star of CY Aqr exhibits a linear period variation rate of (1/ P 0 )( d P / dt ) = (2.132 ± 0.002) × 10 −8 yr −1 for its dominant pulsation mode; (ii) the primary star is disturbed by two companions and part of a triple system; (iii) Companion A has an orbital period of approximately 60.2 yr and Companion B has an orbital period of approximately 50.8 yr. It is highly probable that both Companion A and B are white dwarfs, with Companion A's elliptical orbit displaying an eccentricity of e = 0.139 ± 0.002, which is the lowest confirmed value in similar binary and triple systems to date. Most notably, Companion A and B have masses that are identical within the uncertainties, with a mass ratio exceeding 0.99. Whether this is considered a coincidental event or the result of an underlying mechanism, CY Aqr is an exceptionally rare case that broadens our understanding of multiple star systems and offers a unique opportunity to delve into the enigmatic evolutionary histories of such configurations. Further intriguing characteristics of this system warrant investigation in future studies, based on additional observational data.}, archive = {J_ApJ}, author = {Ming Lian and Jia-Shu Niu and Hui-Fang Xue}, doi = {10.3847/1538-4357/adc376}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {140}, shortjournal = {The Astrophys. J.}, title = {CY aquarii: A triple system with twin companions}, volume = {983}, year = {2025}, }
• (2025). MSA-3D: Dissecting galaxies at z ∼ 1 with high spatial and spectral resolution. ApJ, 983(2), 139. (www)

  @article{ , abstract = {Integral field spectroscopy (IFS) is a powerful tool for understanding the formation of galaxies across cosmic history. We present the observing strategy and first results of MSA-3D, a novel JWST program using multi-object spectroscopy in a slit-stepping strategy to produce IFS data cubes. The program observed 43 normal star-forming galaxies at redshifts 0.5 ≲ z ≲ 1.5, corresponding to the epoch when spiral thin-disk galaxies of the modern Hubble sequence are thought to emerge, obtaining kiloparsec-scale maps of rest-frame optical nebular emission lines with spectral resolution R ≃ 2700. Here we describe the multiplexed slit-stepping method, which is >15 times more efficient than the NIRSpec IFS mode for our program. As an example of the data quality, we present a case study of an individual galaxy at z = 1.104 (stellar mass M * = 10 10.3 M ⊙ , star formation rate, SFR = 3 M ⊙ yr −1 ) with prominent face-on spiral structure. We show that the galaxy exhibits a rotationally supported disk with moderate velocity dispersion ( \sigma =3{6}_{-4}^{+5} km s −1 ), a negative radial metallicity gradient (−0.020 ± 0.002 dex kpc −1 ), a dust attenuation gradient, and an exponentially decreasing SFR density profile that closely matches the stellar continuum. These properties are characteristic of local spirals, indicating that mature galaxies are in place at z ∼ 1. We also describe the customized data reduction and original cube-building software pipelines that we have developed to exploit the powerful slit-stepping technique. Our results demonstrate the ability of JWST slit-stepping to study galaxy populations at intermediate to high redshifts, with data quality similar to current surveys of the z ∼ 0.1 Universe.}, archive = {J_ApJ}, author = {Ivana Barišić and Tucker Jones and Kris Mortensen and Themiya Nanayakkara and Yuguang Chen and Ryan Sanders and James S. Bullock and Kevin Bundy and Claude-André Faucher-Giguère and Karl Glazebrook and Alaina Henry and Mengting Ju and Matthew Malkan and Takahiro Morishita and Danail Obreschkow and Namrata Roy and Juan M. Espejo Salcedo and Alice E. Shapley and Tommaso Treu and Xin Wang and Kyle B. Westfall}, doi = {10.3847/1538-4357/ada617}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {139}, shortjournal = {The Astrophys. J.}, title = {MSA-3D: Dissecting galaxies at z ∼ 1 with high spatial and spectral resolution}, volume = {983}, year = {2025}, }
• (2025). The merging galaxy cluster environment affects the morphology of radio active galactic nuclei. ApJ, 983(2), 138. (www)

  @article{ , abstract = {It has previously been found that the galaxy cluster environment can affect the fueling and evolution of active galactic nuclei (AGN). This work examines the effect of the merging cluster environment on the properties of radio AGN by comparing the radio morphology of cluster members in a sample of four merging and eight relaxed galaxy clusters at low redshift ( z < 0.2). Using 144 MHz data from the LOFAR Two-meter Sky Survey and Zooniverse, we classify the radio morphology of the radio-detected cluster members using the following morphology classes: compact, compact extended, extended, jetted, and disturbed. We find that the merging cluster environment has a statistically significant, higher population proportion of disturbed (bent and head tail) sources, indicating that the merging environment can affect the morphology of cluster radio AGN. We also investigate the number of AGN that are detected in the radio data only and the number that are detected in both the radio and optical data in mergers and nonmergers. We find that the merging cluster environment has a higher population proportion of AGN that are identified only as radio AGN compared to AGN that are identified as both radio and optical AGN. Overall, we find that the merging environment affects certain radio AGN (disturbed and only radio-identified AGN), but not all.}, archive = {J_ApJ}, author = {Mary Rickel and Emily Moravec and Yjan A. Gordon and Martin J. Hardcastle and Jonathon C. S. Pierce and Lawrence E. Bilton and Ian D. Roberts}, doi = {10.3847/1538-4357/adbb5e}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {138}, shortjournal = {The Astrophys. J.}, title = {The merging galaxy cluster environment affects the morphology of radio active galactic nuclei}, volume = {983}, year = {2025}, }
• (2025). Tracing the earliest stages of star and cluster formation in 19 nearby galaxies with PHANGS-JWST and HST: Compact 3.3 μm polycyclic aromatic hydrocarbon emitters and their relation to the optical census of star clusters. ApJ, 983(2), 137. (www)

  @article{ , abstract = {The earliest stages of star and cluster formation are hidden within dense cocoons of gas and dust, limiting their detection at optical wavelengths. With the unprecedented infrared capabilities of JWST, we can now observe dust-enshrouded star formation with ∼10 pc resolution out to ∼20 Mpc. Early findings from PHANGS-JWST suggest that 3.3 μ m polycyclic aromatic hydrocarbon (PAH) emission can identify star clusters in their dust-embedded phases. Here, we extend this analysis to 19 galaxies from the PHANGS-JWST Cycle 1 Treasury survey, providing the first characterization of compact sources exhibiting 3.3 μ m PAH emission across a diverse sample of nearby star-forming galaxies. We establish a selection criteria based on a median color threshold of F300M − F335M = 0.67 at F335M = 20 and identify 1816 sources. These sources are predominantly located in dust lanes, spiral arms, rings, and galaxy centers, with ∼87% showing concentration indices (CIs) similar to optically detected star clusters. Comparison with the PHANGS-HST catalogs suggests that PAH emission fades within ∼3 Myr. The H α equivalent width of PAH emitters is 1–2.8 times higher than that of young PHANGS-HST clusters, providing evidence that PAH emitters are on average younger. Analysis of the bright portions of luminosity functions (which should not suffer from incompleteness) shows that young dusty clusters may increase the number of optically visible ≤3 Myr old clusters in PHANGS-HST by a factor between ∼1.8 × and 8.5 × .}, archive = {J_ApJ}, author = {M. Jimena Rodríguez and Janice C. Lee and Remy Indebetouw and B. C. Whitmore and Daniel Maschmann and Thomas G. Williams and Rupali Chandar and A. T. Barnes and Oleg Y. Gnedin and Karin M. Sandstrom and Erik Rosolowsky and Adam K. Leroy and David A. Thilker and Hwihyun Kim and Jiayi Sun and Ralf S. Klessen and Brent Groves and Aida Wofford and Médéric Boquien and Daniel A. Dale and Leonardo Úbeda and Kirsten L. Larson and Kathryn Grasha and Kelsey E. Johnson and Rebecca C. Levy and Frank Bigiel and Hamid Hassani and Sumit K. Sarbadhicary}, doi = {10.3847/1538-4357/adbb69}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {137}, shortjournal = {The Astrophys. J.}, title = {Tracing the earliest stages of star and cluster formation in 19 nearby galaxies with PHANGS-JWST and HST: Compact 3.3 μm polycyclic aromatic hydrocarbon emitters and their relation to the optical census of star clusters}, volume = {983}, year = {2025}, }
• (2025). Deuterated polycyclic aromatic hydrocarbons in the interstellar medium: Constraints from the orion bar as observed by the james webb space telescope. ApJ, 983(2), 136. (www)

  @article{ , abstract = {The gas-phase abundances of deuterium (D) in the local interstellar medium exhibit considerable regional variations. Particularly, in some regions the gas-phase D abundances are substantially lower than the primordial D abundance generated in the Big Bang after subtracting the astration reduction caused by the Galactic chemical evolution. Deuterated polycyclic aromatic hydrocarbon (PAH) molecules have been suggested as a potential reservoir of the D atoms missing from the gas phase. Recent observations from the James Webb Space Telescope's Near Infrared Spectrograph have revealed how widespread deuterated PAHs are in the Orion Bar through their aliphatic C–D emission at 4.65 μ m and possibly aromatic C–D emission at 4.4 μ m as well. To examine the viability of deuterated PAHs as the D reservoir, we model the infrared emission spectra of small PAH molecules containing various aromatic and aliphatic D atoms in the Orion Bar. We find that small deuterated PAHs exhibit a noticeable emission band at 4.4 or 4.65 μ m even if they contain only one aromatic or aliphatic D atom. We derive N D,ali / N H ≈ 3.4%, the deuteration degree of PAHs measured as the number of aliphatic D atoms (relative to H), from the observed intensity ratios of the 4.65 μ m band to the 3.3 μ m aromatic C–H band. The deuteration degree for aromatically deuterated PAHs is less certain as C–N stretch also contributes to the observed emission around 4.4 μ m. If we attribute it exclusively to aromatic C–D, we derive an upper limit of ≈14% on the deuteration degree, which is capable of accounting for an appreciable fraction of the missing D budget.}, archive = {J_ApJ}, author = {X. J. Yang and Aigen Li}, doi = {10.3847/1538-4357/adbd11}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {136}, shortjournal = {The Astrophys. J.}, title = {Deuterated polycyclic aromatic hydrocarbons in the interstellar medium: Constraints from the orion bar as observed by the james webb space telescope}, volume = {983}, year = {2025}, }
• (2025). Convective overstability in radially global protoplanetary disks. II. impact on planetesimal formation. ApJ, 983(2), 135. (www)

  @article{ , abstract = {The convective overstability (COS) is a hydrodynamic instability occurring in protoplanetary disk (PPD) regions with an adverse radial entropy gradient. It is a potential driver of turbulence and may influence planetesimal formation. In this second paper of our series, we study the effects of the COS on dust dynamics in radially global PPD simulations, focusing on the midplane region, where vertical gravity on the dust is included. Axisymmetric 2D simulations show susceptibility to both the COS and the vertically shearing streaming instability. For a Stokes number τ = 0.1, strong dust clumping occurs only for highly supersolar initial metallicities Z ≳ 0.05. In 3D nonaxisymmetric simulations, the COS generates large-scale, long-lived vortices that have the potential to efficiently concentrate dust, with dust accumulation strengthening as τ increases. For τ = 0.01, no strong clumping occurs even at metallicities as high as Z = 0.1, and vortices remain robust and long-lived. At τ ≈ 0.04, strong dust clumping is observed for solar metallicity ( Z = 0.01) and higher. For τ = 0.1, clumping occurs even at strongly subsolar metallicities ( Z ≳ 0.004), peaking at Z ∼ 0.01–0.03, including solar values. Under these conditions, vortices weaken significantly. At higher metallicities ( Z ≳ 0.04) with τ = 0.1, large-scale vortex formation is suppressed, leading to nearly axisymmetric dust rings, which can still undergo clumping via the classical streaming instability.}, archive = {J_ApJ}, author = {Marius Lehmann and Min-Kai Lin}, doi = {10.3847/1538-4357/adbf06}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {135}, shortjournal = {The Astrophys. J.}, title = {Convective overstability in radially global protoplanetary disks. II. impact on planetesimal formation}, volume = {983}, year = {2025}, }
• (2025). An equilibrium model of the galaxy determined by element abundance gradients. ApJ, 983(2), 134. (www)

  @article{ , abstract = {We present a method to determine the gravitational potential of the Milky Way from measurements of the locations, velocities, and element abundances of stars in the Galactic disk. The method relies on the assumption that the Galaxy is axisymmetric and stationary and that element abundance ratios such as [Fe/H] and [Mg/Fe] are smooth functions of three isolating integrals of motion. We use Fisher Information theory to predict the efficacy of individual abundance ratios to constrain the potential. We also use N -body simulations to test the extent by which secular evolution in the disk introduces statistical and systematic errors into the analysis. We apply our method to a sample of stars from Gaia Data Release 3 and the APOGEE survey and infer the vertical force profile at the position of the Sun and the rotation curve in the midplane and find good agreement with previously published results. The residuals of the model show corrugations in [Fe/H] as a function of L z , the angular momentum component along the spin axis of the Galaxy. Using the correspondence between L z and Galactocentric cylindrical radius, we show that these features line up with the four spiral arms closest to the Sun.}, archive = {J_ApJ}, author = {Lawrence M. Widrow and David W. Hogg and Danny Horta and Haochaun Li and Adrian M. Price-Whelan}, doi = {10.3847/1538-4357/adbf12}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {134}, shortjournal = {The Astrophys. J.}, title = {An equilibrium model of the galaxy determined by element abundance gradients}, volume = {983}, year = {2025}, }
• (2025). Variation of dense gas Mass–Luminosity conversion factor with metallicity in the milky way. ApJ, 983(2), 133. (www)

  @article{ , abstract = {HCN and HCO + are the most common dense gas tracers used both in the Milky Way and external galaxies. The luminosity of HCN and HCO + J = 1 → 0 lines are converted to a dense gas mass by the conversion factor, α Q . Traditionally, this α Q has been considered constant throughout the Galaxy and in other galaxies, regardless of the environment. We analyzed 17 outer Galaxy clouds and five inner Galaxy clouds with metallicities ranging from 0.38 Z ⊙ to 1.29 Z ⊙ . Our analysis indicates that α Q is not constant; instead, it varies with metallicity. The metallicity-corrected α Q derived from the HCN luminosity of the entire cloud is almost three times higher in the outer Galaxy than in the inner Galaxy. In contrast, HCO + seems less sensitive to metallicity. We recommend using the metallicity-corrected dense gas conversion factors {\alpha }_{\mathrm{tot,}\mathrm{gas}}^{{\prime} }(\mathrm{HCN})=19.{5}_{-4.4}^{+5.6}{Z}^{(-1.53\pm 0.59)} and {\alpha }_{\mathrm{tot,}\mathrm{gas}}^{{\prime} }({\mathrm{HCO}}^{+})=21.{4}_{-4.4}^{+5.5}{Z}^{(-1.32\pm 0.55)} for extragalactic studies. Radiation from nearby stars has an effect on the conversion factor of a similar magnitude as that of the metallicity. If we extend the metallicity-corrected scaling relation for HCN to the Central Molecular Zone (CMZ), the value of \alpha ({\rm{HCN}}) becomes one-third to one-half of the local values. This effect could partially account for the low star formation rate per dense gas mass observed in the CMZ.}, archive = {J_ApJ}, author = {Sudeshna Patra and Neal J. Evans and Kee-Tae Kim and Mark Heyer and Andrea Giannetti and Davide Elia and Jessy Jose and Jens Kauffmann and Manash R. Samal and Agata Karska and Swagat R. Das and Gyuho Lee and Geumsook Park}, doi = {10.3847/1538-4357/adbf8d}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {133}, shortjournal = {The Astrophys. J.}, title = {Variation of dense gas Mass–Luminosity conversion factor with metallicity in the milky way}, volume = {983}, year = {2025}, }
• (2025). Frequency-resolved time lags due to X-ray disk reprocessing in AGN. ApJ, 983(2), 132. (www)

  @article{ , abstract = {Over the last years, a number of broadband reverberation mapping campaigns have been conducted to explore the short-term UV and optical variability of nearby AGN. Despite the extensive data collected, the origin of the observed variability is still debated in the literature. Frequency-resolved time lags offer a promising approach to distinguish between different scenarios as they probe variability on different timescales. In this study, we present the expected frequency-resolved lags resulting from X-ray reprocessing in the accretion disk. The predicted lags are found to feature a general shape that resembles that of observational measurements while exhibiting strong dependence on various physical parameters. Additionally, we compare our model predictions to observational data for the case of NGC 5548, concluding that the X-ray illumination of the disk can effectively account for the observed frequency-resolved lags and power spectra in a self-consistent way. To date, X-ray disk reprocessing is the only physical model that has successfully reproduced the observed multiwavelength variability, in both amplitude and time delays, across a range of temporal frequencies.}, archive = {J_ApJ}, author = {Christos Panagiotou and Iossif Papadakis and Erin Kara and Marios Papoutsis and Edward M. Cackett and Michal Dovčiak and Javier A. García and Elias Kammoun and Collin Lewin}, doi = {10.3847/1538-4357/adbf95}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {132}, shortjournal = {The Astrophys. J.}, title = {Frequency-resolved time lags due to X-ray disk reprocessing in AGN}, volume = {983}, year = {2025}, }
• (2025). Modeling the UV/Optical light curve of re-brightening tidal disruption events. ApJ, 983(2), 131. (www)

  @article{ , abstract = {In recent years, a new subclass of tidal disruption events (TDEs) has been reported in the literature. The light curve of these TDEs shows a re-brightening feature in the decline phase after the first peak, which then leads to a second flare. The re-brightening TDEs challenge the existing light-curve fitting tools designed to handle a single flare. In this work, we present a model aimed at reproducing the light curve of the re-brightening TDEs, based on the scenario that the consecutive flares are produced by the same star that experienced two partial TDEs. We also developed a fitting code from this model and applied it to two re-brightening TDEs: AT 2022dbl and AT 2023adr. The light curves of both TDEs are well-fitted. Finally, we forecast the time and peak brightness of the next flare for these two TDEs so that observers can prepare to examine our model.}, archive = {J_ApJ}, author = {Shiyan Zhong}, doi = {10.3847/1538-4357/adc005}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {131}, shortjournal = {The Astrophys. J.}, title = {Modeling the UV/Optical light curve of re-brightening tidal disruption events}, volume = {983}, year = {2025}, }
• (2025). Spectral line search in bright gamma-ray bursts observed by Fermi/GBM. ApJ, 983(2), 130. (www)

  @article{ , abstract = {The recently reported discoveries of emission lines with power-law decay from  ∼37 to  ∼6 MeV in the gamma-ray burst (GRB) 221009A have greatly contributed to probing the physics of GRBs, which also raises the natural question of whether there are more emission lines in bright GRBs. In this work, we search for emission lines in the top 30 highest fluence GRBs in the Gamma-Ray Burst Catalog observed by the Fermi/Gamma-ray Burst Monitor. Although no new lines are confirmed, there are a portion of GRBs that seem to show emission line features in their spectra with mean values of 61 keV, 110 keV, and 2.1 MeV, respectively. However, considering that the redshifts of these GRBs are different, the observed emission line features have almost identical central energy, thus the  ∼110 keV spectral line should be caused by instrumental effects rather than GRB or other astronomical sources. The  ∼61 keV and  ∼2.1 MeV are comparable to 57.6 keV and 2.2 MeV, which are spectral lines confirmed to come from the excited energy level of 127 I and the neutron capture line, respectively, as reported by previous studies. Our findings indicate that various effects may produce emission line-like features in the GRB spectrum and caution should be taken to carefully identify whether they are from GRB, other astronomical sources, or instrumental effects. Finally, the lack of spectral lines searched in other bright GRBs implies the special radiation mechanism of the spectral lines in GRB 221009A.}, archive = {J_ApJ}, author = {Tong-Lei Liao and Yan-Qiu Zhang and Wang-Chen Xue and Shuo Xiao and Shao-Lin Xiong and Xi-Lu Wang and Hua Feng and Chao Zheng and Yue Wang and Jia-Cong Liu and Chen-Wei Wang and Jiao-Jiao Yang and Mei-Xin Hong and Zheng-Huo Jiang and Yang Lai and Xi-Hong Luo}, doi = {10.3847/1538-4357/adc00b}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {130}, shortjournal = {The Astrophys. J.}, title = {Spectral line search in bright gamma-ray bursts observed by Fermi/GBM}, volume = {983}, year = {2025}, }
• (2025). The critical role of dust on the [O iii] planetary nebula luminosity function’s bright-end cutoff. ApJ, 983(2), 129. (www)

  @article{ , abstract = {We examine the relationship between circumnebular extinction and core mass for sets of [O iii ]-bright planetary nebulae (PNe) in the Large Magellanic Cloud and M31. We confirm that for PNe within 1 magnitude of the planetary nebula luminosity function's (PNLF's) bright-end cutoff magnitude ( M * ), higher core-mass PNe are disproportionally affected by greater circumnebular extinction. We show that this result can explain why the PNLF cutoff is so insensitive to population age. In younger populations, the higher-mass, higher-luminosity cores experience greater circumnebular extinction from the dust created by their asymptotic giant branch (AGB) progenitors compared to the lower-mass cores. We further show that when our core-mass–nebular extinction law is combined with post-AGB stellar evolutionary models, the result is a large range of population ages where the brightest PNe all have nearly identical [O iii ] luminosities. Finally, we note that while there is some uncertainty about whether the oldest stellar populations can produce PNe as bright as M * , this issue is resolved if the initial–final mass relation (IFMR) for the lowest-mass stars results in slightly more massive cores, as observed in some clusters. Alternatively, introducing a small amount of intrinsic scatter (0.022 M ⊙ ) into the IFMR also addresses this uncertainty.}, archive = {J_ApJ}, author = {George H. Jacoby and Robin Ciardullo}, doi = {10.3847/1538-4357/adc0fb}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {129}, shortjournal = {The Astrophys. J.}, title = {The critical role of dust on the [O iii] planetary nebula luminosity function’s bright-end cutoff}, volume = {983}, year = {2025}, }
• (2025). The spectral variation behavior of fermi-LAT blazars. ApJ, 983(2), 128. (www)

  @article{ , abstract = {In this study, we analyze the ∼16 yr Fermi-Large Area Telescope data of 160 blazars consisting of 92 flat-spectrum radio quasars (FSRQs), 64 BL Lacertae (BL Lac)–type objects, and 4 blazar-candidates-of-unknown-type objects, and investigate their spectral variation. By fitting a linear model ( y = kx + b ) to the monthly binned flux-index plots, we find that most of the FSRQs (∼89%) display a harder-when-brighter trend ( k > 0), while the majority of BL Lac–type objects (∼64%) exhibit a softer-when-brighter trend ( k < 0). By plotting their slope ( k ) versus their variability index and inverse Compton (IC) peak frequency, we find a moderate positive correlation between k and the variability index and a moderate negative correlation between k and the IC peak frequency, which we name as the gamma-ray variability sequence of blazars. Additionally, eight blazars may not follow the linear variation trend, particularly in PKS 0537-441, AP Librae, and PKS 1510-089. Additional very-high-energy gamma-ray emission components may be the cause of the nonlinear variation trend.}, archive = {J_ApJ}, author = {Junhao Deng and Yunguo Jiang}, doi = {10.3847/1538-4357/adc106}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {128}, shortjournal = {The Astrophys. J.}, title = {The spectral variation behavior of fermi-LAT blazars}, volume = {983}, year = {2025}, }
• (2025). A systematic NLTE study of very metal-poor stars with metallicity down to −4.3 dex. i. global stellar parameters based on high-resolution spectra. ApJ, 983(2), 127. (www)

  @article{ , abstract = {Very metal-poor (VMP) stars provide a record of the chemical composition and dynamics of the early Galaxy. Based on the high-resolution and high signal-to-noise ratio spectra from the Subaru Telescope for 103 VMP stars, in this series of papers we homogeneously investigate the nonlocal thermodynamic equilibrium (NLTE) abundances of important astrophysical elements. This sample covers a wide metallicity range from [Fe/H] ∼ −1.7 dex down to −4.3 dex, including 13 objects with [Fe/H] ≤ −3.0 dex. Here, we present a set of homogeneous stellar atmospheric parameters, including the effective temperature, surface gravity, metallicity, and microturbulence velocity with the spectroscopic method, and the NLTE line formation for both Fe i and Fe ii in the classical one-dimensional model atmospheres have been considered. The NLTE effects of the Fe i lines range from ∼0.03 dex to ∼0.3 dex, and increase with decreasing metallicity. In addition, they depend on the surface gravity, which generally increases with decreasing {\mathrm{log}}\,g . The largest NLTE effects can be found for the giants of {\mathrm{log}}\,g ∼ 2.5 dex. For dwarfs and subgiants, our final effective temperatures are consistent with those derived from the T IRFM scales of A. Alonso et al. with a mean difference of 7.1 ± 100.2 K, while for giants, our results are slightly lower than those from the T IRFM scales of A. Alonso et al. with a mean difference of −69.5 ± 94.1 K. For dwarfs and subgiants, the spectroscopically derived surface gravity is consistent with that estimated based on the Gaia DR3 parallax; however, for giants, the former leads to a 0.2 dex lower surface gravity.}, archive = {J_ApJ}, author = {Jianrong Shi and Gang Zhao and Shuai Liu and Zeming Zhou and Haining Li and Hongliang Yan and Sofya Alexeeva and Huawei Zhang and Wako Aoki and Tadafumi Matsuno and Jingkun Zhao and Huiling Chen and Yufu Shen}, doi = {10.3847/1538-4357/adc127}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {127}, shortjournal = {The Astrophys. J.}, title = {A systematic NLTE study of very metal-poor stars with metallicity down to −4.3 dex. i. global stellar parameters based on high-resolution spectra}, volume = {983}, year = {2025}, }
• (2025). Observational comparison between confined and eruptive flares: Magnetohydrodynamics instability parameters in a similar magnetic configuration. ApJ, 983(2), 126. (www)

  @article{ , abstract = {Unstable states of the solar coronal magnetic field structure result in various flare behaviors. In this study, we compared the confined and eruptive flares that occurred under similar magnetic circumstances in the active region 12673, on 2017 September 6, using the twist number, decay index, and height of magnetic field lines to identify observational behaviors of the flare eruption. We investigated the parameters from the magnetic field lines involved in an initial energy release, which were identified from the positions of the core of flare ribbons, i.e., flare kernels. The magnetic field lines were derived by nonlinear force-free field modeling calculated from the photospheric vector magnetic field obtained by the Solar Dynamics Observatory SDO/Helioseismic and Magnetic Imager, and flare kernels were identified from the 1600 Å data obtained by the SDO/Atmospheric Imaging Assembly. The twist number of all the magnetic field lines in the confined flare was below 0.6; however, the twist number in seven out of 24 magnetic field lines in the eruptive flare was greater than 0.6. These lines were tall. It is found that the decay index is not a clear discriminator of the confined and eruptive flares. Our study suggests that some magnetic field lines in the kink instability state may be important for eruptive flares, and that taller magnetic field lines may promote flare eruption.}, archive = {J_ApJ}, author = {Kouhei Teraoka and Daiki Yamasaki and Yusuke Kawabata and Shinsuke Imada and Toshifumi Shimizu}, doi = {10.3847/1538-4357/adc12d}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {126}, shortjournal = {The Astrophys. J.}, title = {Observational comparison between confined and eruptive flares: Magnetohydrodynamics instability parameters in a similar magnetic configuration}, volume = {983}, year = {2025}, }
• (2025). Double beam instability for the mercury upstream waves. ApJ, 983(2), 125. (www)

  @article{ , abstract = {Mercury shock-upstream region is plasma physically of great interest, as the solar wind plasma may encounter two ion beams, forming a double-beam plasma system. Properties of the double-beam instability are studied semianalytically using the magnetoionic theory (cold plasma waves including beams), such as the unstable mode, the resonance wavenumbers, and the growth rates, for various beam configurations. The cold plasma wave theory supports the idea that both the foreshock ions and the pickup ions can potentially drive the right-hand beam instability, and moreover, the instability may run simultaneously for the two beam species. Further nonlinear wave evolution scenarios are discussed, such as independent parametric instabilities and driven wave–wave couplings causing low-frequency and high-frequency splits of the waves. The double-beam instability is testable against numerical simulations of the plasma waves as well as magnetic field observations by the MESSENGER spacecraft and the upcoming BepiColombo spacecraft.}, archive = {J_ApJ}, author = {Y. Narita and U. Motschmann and H. Comişel and D. Schmid}, doi = {10.3847/1538-4357/adc1bc}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {125}, shortjournal = {The Astrophys. J.}, title = {Double beam instability for the mercury upstream waves}, volume = {983}, year = {2025}, }
• (2025). Hyperluminous supersoft X-ray sources in the chandra catalog. ApJ, 983(2), 124. (www)

  @article{ , abstract = {Hyperluminous supersoft X-ray sources (HSSs), such as bright extragalactic sources characterized by particularly soft X-ray spectra, offer a unique opportunity to study accretion onto supermassive black holes in extreme conditions. Examples of hyperluminous supersoft sources are tidal disruption events (TDEs), systems exhibiting quasiperiodic eruptions, changing-look active galactic nuclei, and anomalous nuclear transients. Although these objects are rare phenomena among the population of X-ray sources, we developed an efficient algorithm to identify promising candidates exploiting archival observations. In this work, we present the results of a search for HSSs in the recently released Chandra catalog of serendipitous X-ray sources. This archival search has been performed via both a manual implementation of the algorithm we developed and a novel machine learning–based approach. This search identified a new TDE, which might have occurred in an intermediate-mass black hole. This event occurred between 2001 and 2002, making it one of the first TDEs ever observed by Chandra.}, archive = {J_ApJ}, author = {Andrea Sacchi and Kevin Paggeot and Steven Dillmann and Juan Rafael Martínez-Galarza and Peter Kosec}, doi = {10.3847/1538-4357/adc256}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {124}, shortjournal = {The Astrophys. J.}, title = {Hyperluminous supersoft X-ray sources in the chandra catalog}, volume = {983}, year = {2025}, }
• (2025). Revisiting physical properties of mock globular cluster tidal tails. ApJ, 983(2), 123. (www)

  @article{ , abstract = {In this work, we present results of the first in-depth analysis of extra-tidal mock stars of Milky Way globular clusters recently generated by S. M. Grondin et al. Particularly, we selected a sample of globular clusters with a general consensus of being formed in the bulge or in the disk of the Milky Way. From the catalog, we estimated the width and the dispersion in the z -component of the angular momentum and in the line-of-sight and tangential velocities of their tidal tails, and compared the results with those predicted by cosmological simulations of K. Malhan et al. and observations. We found that the resulting values of these four quantities are not in agreement with an in situ formation of the associated globular clusters. On average, the resulting widths agree with an in situ origin, while the dispersion in the z -component of the angular momentum, and the dispersion in the line-of-sight and tangential velocities fail in matching this formation scenario. The four quantities derived for globular clusters formed in the bulge or in the disk show similar correlations with the stream length, namely, the width and the dispersion in the z -component of the angular momentum increase with the stream length, while the bulk of dispersion values in the line-of-sight and tangential velocities is around 12 km s −1 along the mock stream.}, archive = {J_ApJ}, author = {Andrés E. Piatti}, doi = {10.3847/1538-4357/adc385}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {123}, shortjournal = {The Astrophys. J.}, title = {Revisiting physical properties of mock globular cluster tidal tails}, volume = {983}, year = {2025}, }
• (2025). Alignment of Blue/Green and red early-type galaxies with large-scale filaments reveals distinct evolutionary pathways. ApJ, 983(2), 122. (www)

  @article{ , abstract = {We investigate the alignment of nonred early-type galaxies (ETGs) with blue or green colors within large-scale filaments and compare this alignment pattern with that of red ETGs. Our analysis reveals a significant alignment of the major axes of red ETGs with the orientations of their host cosmic filaments, consistent with prior research. In contrast, nonred ETGs show no significant alignment signal. This divergence in alignment behavior between nonred and red ETGs plausibly suggests distinct evolutionary pathways for nonred and red ETGs.}, archive = {J_ApJ}, author = {Yu Rong and Peng Wang}, doi = {10.3847/1538-4357/adc4de}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {122}, shortjournal = {The Astrophys. J.}, title = {Alignment of Blue/Green and red early-type galaxies with large-scale filaments reveals distinct evolutionary pathways}, volume = {983}, year = {2025}, }
• (2025). EPOCHS. XI. the structure and morphology of galaxies in the epoch of reionization to z ∼ 12.5. ApJ, 983(2), 121. (www)

  @article{ , abstract = {We present a structural analysis of 520 galaxy candidates at 6.5 < z < 12.5 with a signal-to-noise ratio of >10 σ in the F444W filter taken from the EPOCHS v1 sample, consisting of uniformly reduced deep JWST NIRCam data covering the CEERS, JADES GOODS-S, NGDEEP, SMACS-0723, GLASS, and PEARLS surveys. We use standard software to fit single Sérsic models to each galaxy in the rest-frame optical and extract their parametric structural parameters (Sérsic index, half-light radius, and axis ratio) and Morfometryka to measure their nonparametric concentration and asymmetry parameters. We find a wide range of sizes for these early galaxies, with galaxy sizes overall continuing to become progressively smaller in the high-redshift regime, following {R}_{e}=\left(2.12\pm 0.28\right){\left(1+z\right)}^{-0.67\pm 0.06} kpc. We further find a galaxy size–mass correlation up to z ∼ 12, with galaxies of a given mass also becoming smaller. Using nonparametric methods, we find that galaxy merger fractions, classified through asymmetry parameters, at these redshifts remain consistent with those in the literature, maintaining a value of f m ∼ 0.12 ± 0.07 showing little dependence with redshift when combined with the literature at z > 4. We find that galaxies that are smaller in size also appear rounder, with an excess of high axis ratio objects. Finally, we artificially redshift a subsample of our objects to determine how robust the observational trends we see are, determining that the observed trends are due to real evolutionary effects, rather than being a consequence of redshift effects.}, archive = {J_ApJ}, author = {Lewi Westcott and Christopher J. Conselice and Thomas Harvey and Duncan Austin and Nathan Adams and Fabricio Ferrari and Leonardo Ferreira and James Trussler and Qiong Li and Vadim Rusakov and Qiao Duan and Honor Harris and Caio Goolsby and Thomas J. Broadhurst and Dan Coe and Seth H. Cohen and Simon P. Driver and Jordan C. J. D’Silva and Brenda Frye and Norman A. Grogin and Nimish P. Hathi and Rolf A. Jansen and Anton M. Koekemoer and Madeline A. Marshall and Rafael Ortiz and Nor Pirzkal and Aaron Robotham and Russell E. Ryan and Jake Summers and Christopher N. A. Willmer and Rogier A. Windhorst and Haojing Yan}, doi = {10.3847/1538-4357/adb968}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {121}, shortjournal = {The Astrophys. J.}, title = {EPOCHS. XI. the structure and morphology of galaxies in the epoch of reionization to z ∼ 12.5}, volume = {983}, year = {2025}, }
• (2025). Transition from vortical to alfvénic-like fermi electron acceleration in magnetic reconnection with increasing guide field. ApJ, 983(2), 120. (www)

  @article{ , abstract = {Using particle-in-cell simulations of magnetic reconnection (MR), we investigate how the changing magnetic guide field strength impacts the evolution of electron Kelvin–Helmholtz instability (EKHI) and the associated Fermi electron acceleration proposed by H. Che & G. P. Zank. Through this investigation, an Alfvénic-like Fermi electron acceleration mechanism is discovered for strong guide field MR B g / B 0 > 2.5, where B g is the magnetic guide field. The electrons are accelerated by the intensive electric potential produced through \delta {{\boldsymbol{U}}}_{{\boldsymbol{i}}}\times {\boldsymbol{B}} , where the ion velocity fluctuations \delta {{\boldsymbol{U}}}_{{\boldsymbol{i}}} propagate parallel to the direction of the Alfvén-like waves. Differing from the two-stage second-order Fermi acceleration produced by the stochastic electric field of EKHI, the Alfvén-like wave mechanism is a much more efficient one-stage process that produces a much harder power-law electron energy spectrum, with an index ∼2, than that of the EKHI, with an index ∼4.}, archive = {J_ApJ}, author = {C. Crawford and H. Che and G. P. Zank and A. O. Benz}, doi = {10.3847/1538-4357/adbc60}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {120}, shortjournal = {The Astrophys. J.}, title = {Transition from vortical to alfvénic-like fermi electron acceleration in magnetic reconnection with increasing guide field}, volume = {983}, year = {2025}, }
• (2025). Cosmological simulations of stellar halos with gaia Sausage–Enceladus analogs: Two sausages, one bun?. ApJ, 983(2), 119. (www)

  @article{ , abstract = {Observations of the Milky Way's stellar halo find that it is predominantly comprised of a radially biased population of stars, dubbed the Gaia Sausage–Enceladus, or GSE. These stars are thought to be debris from dwarf galaxy accretion early in the Milky Way's history. Though typically considered to be from a single merger, it is possible that the GSE debris has multiple sources. To investigate this possibility, we use the I llustris TNG50 simulation to identify stellar accretion histories in 98 Milky Way analogs—the largest sample for which such an identification has been performed—and find GSE-like debris in 32, with two-merger GSEs accounting for a third of these cases. Distinguishing single-merger GSEs from two-merger GSEs is difficult in common kinematic spaces, but differences are more evident through chemical abundances and star formation histories. This is because single-merger GSEs are typically accreted more recently than the galaxies in two-merger GSEs: the median infall times (with 16th and 84th percentiles) are 5.{9}_{-2.0}^{+3.3} and 10.{7}_{-3.7}^{+1.2} Gyr ago for single- and two-merger scenarios, respectively. The systematic shifts in abundances and ages that occur as a result suggest that efforts in modeling these aspects of the stellar halo prove ever-important in understanding its assembly.}, archive = {J_ApJ}, author = {Dylan Folsom and Mariangela Lisanti and Lina Necib and Danny Horta and Mark Vogelsberger and Lars Hernquist}, doi = {10.3847/1538-4357/adbe31}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {119}, shortjournal = {The Astrophys. J.}, title = {Cosmological simulations of stellar halos with gaia Sausage–Enceladus analogs: Two sausages, one bun?}, volume = {983}, year = {2025}, }
• (2025). Behavior of the lyα damping wings as a function of reionization topology. ApJ, 983(2), 118. (www)

  @article{ , abstract = {The damping wing signatures in high-redshift quasars have proven instrumental in studying the epoch of reionization. With the upcoming Euclid mission set to discover many more quasars, it is crucial to explore what this new set of quasars might reveal not only about the reionization history, but also about its topology. The topology should influence the shape and variation of quasar-damping wing signals across sightlines. We use 21cmFAST to generate patchy reionization models in cosmological volumes with diverse astrophysical parameters for the ionizing sources. We examine the median and the sightline-to-sightline variation (ΔSW 68 ) for an ensemble of damping wing signals. We find that the neutral fraction x H I , quasar lifetime t q , quasar host halo mass M qso , and minimum dark-matter halo mass (that can support star formation) {M}_{\min } significantly impact the median signal. Parameters tied to the reionization topology, like x H I and {M}_{\min } , strongly affect ΔSW 68 , compared with t q . Our findings highlight that quasar damping wings are sensitive to {M}_{\min } , a key variable linking reionization topology, history, and feedback processes. We also explore the convergence of damping wing signals and ionized bubble sizes with box size. We present a suite of models to assess the ability of future quasar samples to constrain astrophysical model parameters and the additional systematic uncertainty on the neutral fraction incurred when fixed to a single fiducial value.}, archive = {J_ApJ}, author = {Yash M. Sharma and Frederick B. Davies and Prakash Gaikwad and Fahad Nasir and Sarah E. I. Bosman}, doi = {10.3847/1538-4357/adbe6d}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {118}, shortjournal = {The Astrophys. J.}, title = {Behavior of the lyα damping wings as a function of reionization topology}, volume = {983}, year = {2025}, }
• (2025). Neutron-capture element abundances of 491 stars in milky way dwarf satellite galaxies from medium-resolution spectra. ApJ, 983(2), 117. (www)

  @article{ , abstract = {The chemical compositions of evolved stars in Local Group dwarf spheroidal galaxies (dSphs) provide insight into the galaxy's past star formation and nucleosynthesis. Neutron-capture element abundances are especially interesting. In particular, s -process elements can provide a third chemical clock for resolving star formation histories in addition to core-collapse and Type Ia supernovae. Likewise, the primary sites of the r -process are still areas of extensive research. Until now, the number of stars with neutron-capture element abundances in dSphs has been limited by the need for stars bright enough for high-resolution spectroscopy. We present abundance measurements of the neutron-capture elements Sr, Y, Ba, and Eu with errors <0.4 dex—as well as new measurements of Mg—in 491 stars in Sculptor, Fornax, Draco, Sextans, and Ursa Minor. The large number of stars in our sample is possible because we used medium-resolution spectra from the DEIMOS spectrograph, assembling the largest homogeneous set of neutron-capture abundances in dSphs to date. By utilizing the abundances of both s - and r -process elements, we find evidence of an s -process contribution at early times in Sculptor from our measurements of [Ba/Fe]. This is a potential signature of s -process nucleosynthesis in fast-rotating massive stars. By comparing our measurements of [Eu/Fe] with [Mg/Fe], we show the need for an r -process source that has a short delay time to enrich stars in the dSphs. Thus, neutron star mergers are likely not the sole source of r -process material in dSphs.}, archive = {J_ApJ}, author = {Lauren E. Henderson and Evan N. Kirby and Mithi A. C. de los Reyes and Roman Gerasimov and Viraj Manwadkar}, doi = {10.3847/1538-4357/adbe7d}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {117}, shortjournal = {The Astrophys. J.}, title = {Neutron-capture element abundances of 491 stars in milky way dwarf satellite galaxies from medium-resolution spectra}, volume = {983}, year = {2025}, }
• (2025). Simultaneous multiwavelength observations of the repeating fast radio burst FRB 20190520B with swift and FAST. ApJ, 983(2), 116. (www)

  @article{ , abstract = {Among several dozen known repeating fast radio bursts, those precisely localized offer the best opportunities to explore their multiwavelength counterparts, which are key to uncovering their origins. Here we report our X-ray, ultraviolet (UV), and optical observations with the Swift satellite of the repeating FRB 20190520B, in coordination with simultaneous radio observations with the Five-hundred-meter Aperture Spherical radio Telescope (FAST). Our aim was to detect potentially associated multiwavelength bursts and identify any persistent multiwavelength counterparts to the associated persistent radio source (PRS). While a total of 10 radio bursts were detected by FAST during the Swift observations, we detected no X-ray, UV, or optical bursts in accompany with the radio bursts. We obtained the energy upper limits (3 σ ) on any multwavelength bursts as follows: 5.03 × 10 47 erg in the hard X-ray band (15–150 keV), 7.98 × 10 45 erg in the soft X-ray band (0.3–10 keV), and 4.51 × 10 44 erg in the U band (3465 Å), respectively. The energy ratio between soft X-ray (0.3–10 keV) and radio emission of the bursts is constrained as <6 × 10 7 , and the ratio between optical ( U band) and radio as <1.19 × 10 6 . We detect no multiwavelength counterpart to the PRS. The 3 σ luminosity upper limits are 1.04 × 10 47 (15–150 keV), 8.81 × 10 42 (0.3–10 keV), 9.26 × 10 42 (UVW1), and 2.54 × 10 42 erg s −1 ( U ), respectively. We show that the PRS is much more radio-loud than representative pulsar wind nebulae, supernova remnants, extended jets of Galactic X-ray binaries, and ultraluminous X-ray sources, suggestive of boosted radio emission of the PRS.}, archive = {J_ApJ}, author = {Zhen Yan and Wenfei Yu and Kim L. Page and Jie Lin and Di Li and Chenhui Niu and Casey Law and Bing Zhang and Shami Chatterjee and Xian Zhang and Reshma Anna-Thomas}, doi = {10.3847/1538-4357/adbef0}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {116}, shortjournal = {The Astrophys. J.}, title = {Simultaneous multiwavelength observations of the repeating fast radio burst FRB 20190520B with swift and FAST}, volume = {983}, year = {2025}, }
• (2025). Triple evolution pathways to black hole low-mass X-ray binaries: Insights from v404 cygni. ApJ, 983(2), 115. (www)

  @article{ , abstract = {A recent discovery shows that V404 Cygni, a prototypical black hole low-mass X-ray binary (BH-LMXB) is a hierarchical triple: the BH and donor star are orbited by a 1.2 M ⊙ tertiary at a distance of at least 3500 au. Motivated by this system, we evolve a grid of ∼50,000 triple star systems, spanning a broad range of initial orbits. Our calculations employ MESA stellar evolution models, using POSYDON , and self-consistently track the effects of eccentric Kozai–Lidov (EKL) oscillations, mass loss, tides, and BH natal kicks. In our simulations, the progenitors of V404 Cygni-like systems have initial outer separations of 1000–10,000 au and inner separations of ∼100 au, such that they avoid Roche lobe overflow most of the time. Later on, EKL oscillations drive the inner binary to high eccentricities until tides shrink the orbit and mass transfer begins. Notably, such systems only form in simulations with very weak black hole natal kicks (≲5 km s −1 ) because stronger kicks unbind the tertiaries. Our simulations also predict a population of BH-LMXB triples that form via the classical common-envelope channel, when the BH progenitor does overflow its Roche lobe. The formation rate for this channel is also higher in triples than in isolated binaries because early EKL oscillations cause inner binaries with a wider range of initial separations to enter and survive a common envelope. Our calculations demonstrate that at least some stellar BHs form with extremely weak kicks, and that triple evolution is a significant formation channel for BH-LMXBs.}, archive = {J_ApJ}, author = {Cheyanne Shariat and Smadar Naoz and Kareem El-Badry and Kyle Akira Rocha and Vicky Kalogera and Alexander P. Stephan and Kevin B. Burdge and Isabel Angelo}, doi = {10.3847/1538-4357/adbf01}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {115}, shortjournal = {The Astrophys. J.}, title = {Triple evolution pathways to black hole low-mass X-ray binaries: Insights from v404 cygni}, volume = {983}, year = {2025}, }
• (2025). Simulation of binary-single interactions in AGN disk. i. gas-enhanced binary orbital hardening. ApJ, 983(2), 114. (www)

  @article{ , abstract = {Stellar-mass binary black hole (BBH) mergers within the accretion disks of active galactic nuclei may contribute to gravitational wave (GW) events detected by ground-based GW detectors. In particular, the interaction between a BBH and a single stellar-mass black hole (sBH), known as the binary-single interaction (BSI) process, can potentially lead to GW events with detectable nonzero eccentricity. Previous studies of the BSI process, which neglected the effects of gas, showed that BSIs contribute non-negligibly to GW events in a coplanar disk environment. In this work, we conduct a series of two-dimensional hydrodynamical and N -body simulations to explore the BSI in a gas environment by coupling REBOUND with Athena++. We perform 360 simulation runs, spanning parameters in disk surface density Σ 0 and impact parameter b . We find that the gas-induced energy dissipation within the three-body system becomes significant if the encounter velocity between the sBHs is sufficiently large (≫ c s ). Our simulation results indicate that approximately half of the end states of the BSI are changed by gas. Furthermore, at higher gas density, the number of close encounters during the BSI process will increase, and the end-state BBHs tend to be more compact. Consequently, the presence of gas may shorten the GW merger timescale for end-state BBHs and increase the three-body merger rate.}, archive = {J_ApJ}, author = {Mengye Wang and Yiqiu Ma and Hui Li and Qingwen Wu and Ya-Ping Li and Xiangli Lei and Jiancheng Wu}, doi = {10.3847/1538-4357/adbf8e}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {114}, shortjournal = {The Astrophys. J.}, title = {Simulation of binary-single interactions in AGN disk. i. gas-enhanced binary orbital hardening}, volume = {983}, year = {2025}, }
• (2025). How low can q go?. ApJ, 983(2), 113. (www)

  @article{ , abstract = {Gravitational instability plays a substantial role in the evolution of galaxies. Various schemes to include it in galaxy evolution models exist, generally assuming that the Toomre Q parameter is self-regulated to Q crit , the critical Q dividing stable from unstable conditions in a linear stability analysis. This assumption is in tension with observational estimates of Q that find values far below any plausible value of Q crit . While the observations are subject to some uncertainty, this tension can more easily be relieved on the theoretical side by relaxing the common assumption that Q ≥ Q crit . Based on observations of both z ∼ 2 disks and local face-on galaxies, we estimate the effect of gravitational instability necessary to balance out every other physical process that affects Q . In particular, we find that the disk's response to low Q values can be described by simple functions that depend only on Q . These response functions allow galaxies to maintain Q values below Q crit in equilibrium over a wide range of parameters. Extremely low values of Q are predicted when the gas surface density is ≳10 3 M ⊙ pc −2 , the rotation curve provides minimal shear, the orbital time becomes long, and/or when the gas is much more unstable than the stellar component. We suggest that these response functions should be used in place of the Q ≥ Q crit ansatz.}, archive = {J_ApJ}, author = {John C. Forbes}, doi = {10.3847/1538-4357/adbf91}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {113}, shortjournal = {The Astrophys. J.}, title = {How low can q go?}, volume = {983}, year = {2025}, }
• (2025). Multiwavelength evidence for two new candidate transitional millisecond pulsars in the subluminous disk state: 4FGL j0639.1-8009 and 4FGL j1824.2+1231. ApJ, 983(2), 112. (www)

  @article{ , abstract = {We report the discovery of two new Galactic accreting compact objects consistent with the respective positions of the unassociated Fermi-LAT γ -ray sources 4FGL J0639.1-8009 and 4FGL J1824.2+1231. A combination of new and archival X-ray data from Chandra, XMM-Newton, Swift/XRT, and eROSITA reveals a variable X-ray source in each γ -ray error ellipse. Both candidate counterparts show power-law spectra with photon indices Γ ∼ 1.7–1.9. Optical follow-up photometry and spectroscopy show rapid high-amplitude variability unrelated to orbital motion and persistent accretion disk spectra for both objects. We demonstrate that the properties of these X-ray/optical sources are at odds with the known phenomenology of accreting white dwarfs, but are consistent with the observed properties of the subluminous disk state of transitional millisecond pulsars. This brings the census of confirmed or candidate transitional millisecond pulsars in the Galactic field to nine. We show this potentially represents ≲10% of the total population of transitional millisecond pulsars within 8 kpc.}, archive = {J_ApJ}, author = {Rebecca Kyer and Subhroja Roy and Jay Strader and Ryan Urquhart and Isabella Molina and Peter Craig and Laura Chomiuk}, doi = {10.3847/1538-4357/adc128}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {112}, shortjournal = {The Astrophys. J.}, title = {Multiwavelength evidence for two new candidate transitional millisecond pulsars in the subluminous disk state: 4FGL j0639.1-8009 and 4FGL j1824.2+1231}, volume = {983}, year = {2025}, }
• (2025). Inferring jet structure and viewing angles of gamma-ray burst jets from early rising optical afterglows. ApJ, 983(2), 111. (www)

  @article{ , abstract = {We present the first systematic investigation of off-axis jets in gamma-ray bursts based on rising optical afterglows. As a pilot study, we selected eight well-observed bright optical afterglows and performed a Bayesian inference using two different jet models: a Gaussian-structured jet and a homogeneous top-hat jet. Assuming an adiabatic evolution of the fireball through a constant-density ambient medium, we derived the key afterglow parameters: viewing angle ( θ v ), jet opening angle ( θ j for top-hat jets) or characteristic angle ( θ c for Gaussian jets), ambient medium number density n 0 , and B measuring the downstream magnetic field strength. The inferred viewing angles of the sample range from 0.4° to 9.7°. Our results identify delayed optical peaks (occurring hundreds to thousands of seconds postburst) and low luminosity as key signatures of misaligned jets, with slow rises to peak suggesting structured jets. We further observe a correlation between the rest-frame peak time and the degree of misalignment in optical light curves. A larger sample size is required to confirm this.}, archive = {J_ApJ}, author = {Sreelakshmi P. Chakyar and Lekshmi Resmi}, doi = {10.3847/1538-4357/adb626}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {111}, shortjournal = {The Astrophys. J.}, title = {Inferring jet structure and viewing angles of gamma-ray burst jets from early rising optical afterglows}, volume = {983}, year = {2025}, }
• (2025). JWST-IPA: Chemical inventory and spatial mapping of ices in the protostar HOPS 370—Evidence for an opacity hole and thermal processing of ices. ApJ, 983(2), 110. (www)

  @article{ , abstract = {The composition of protoplanetary disks, and hence the initial conditions of planet formation, may be strongly influenced by the infall and thermal processing of material during the protostellar phase. The composition of dust and ice in protostellar envelopes, shaped by energetic processes driven by the protostar, serves as the fundamental building material for planets and complex organic molecules. As part of the JWST General Observers program, "Investigating Protostellar Accretion," we observed an intermediate-mass protostar HOPS 370 (OMC2-FIR3) using NIRSpec integral field unit and Mid-Infrared Instrument medium-resolution spectroscopy. This study presents the gas and ice phase chemical inventory revealed with the JWST in the spectral range of ∼2.9–28 μ m and explores the spatial variation of volatile ice species in the protostellar envelope. We find evidence for the thermal processing of ice species throughout the inner envelope. We present the first high-spatial resolution (∼80 au) maps of key volatile ice species H 2 O, CO 2 , 13 CO 2 , CO, and OCN − , which reveal a highly structured and inhomogeneous density distribution of the protostellar envelope, with a deficiency of ice column density that coincides with the jet/outflow shocked knots. Further, we observe high relative crystallinity of H 2 O ice around the shocked knot seen in the H 2 and OH wind/outflow, which can be explained by a lack of outer colder material in the envelope along the line of sight due to the irregular structure of the envelope. These observations show clear evidence of thermal processing of the ices in the inner envelope, close to the outflow cavity walls, heated by the luminous protostar.}, archive = {J_ApJ}, author = {Himanshu Tyagi and P. Manoj and Mayank Narang and S. Thomas Megeath and Will R. M. Rocha and Nashanty Brunken and Adam E. Rubinstein and Robert Gutermuth and Neal J. Evans and Ewine F. Van Dishoeck and Samuel Federman and Dan M. Watson and David A. Neufeld and Guillem Anglada and Henrik Beuther and Alessio Caratti o Garatti and Leslie W. Looney and Pooneh Nazari and Mayra Osorio and Thomas Stanke and Yao-Lun Yang and Tyler L. Bourke and William J. Fischer and Elise Furlan and Joel Green and Nolan Habel and Pamela Klaassen and Nicole Karnath and Hendrik Linz and James Muzerolle and John J. Tobin and Prabhani Atnagulov and Rohan Rahatgaonkar and Patrick Sheehan and Katerina Slavicinska and Amelia M. Stutz and Lukasz Tychoniec and Scott Wolk and Wafa Zakri}, doi = {10.3847/1538-4357/adb71f}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {110}, shortjournal = {The Astrophys. J.}, title = {JWST-IPA: Chemical inventory and spatial mapping of ices in the protostar HOPS 370—Evidence for an opacity hole and thermal processing of ices}, volume = {983}, year = {2025}, }
• (2025). Multiwavelength study of a hyperluminous X-ray source near NGC 6099: A strong IMBH candidate. ApJ, 983(2), 109. (www)

  @article{ , abstract = {We report on the intriguing properties of a variable X-ray source projected at the outskirts of the elliptical galaxy NGC 6099 ( d ≈ 139 Mpc). If truly located near NGC 6099, this is a hyperluminous X-ray source that reached an X-ray luminosity L X ≈ a few times 10 42 erg s −1 in 2012 February (XMM-Newton data), about 50–100 times brighter than in 2009 May (Chandra) and 2023 August (XMM-Newton). The X-ray spectrum was soft at all three epochs, with a thermal component at kT ≈ 0.2 keV and a power-law photon index >3. Such properties make it a strong candidate for an intermediate-mass black hole (IMBH). We also discovered a point-like, blue optical counterpart ( m g ,Vega ≈ 24.7 mag, M g ,Vega ≈ −11.2 mag), from images taken by the Canada–France–Hawaii Telescope and later confirmed with Hubble Space Telescope observations. The optical continuum can be modeled as stellar emission from a compact star cluster or an X-ray-irradiated accretion disk, consistent with the IMBH scenario. We discuss alternative explanations for the nature of this system. A possible scenario is tidal stripping of an orbiting star, with repeated X-ray outbursts every few years. An alternative possibility is that the thermal X-ray emission seen in 2009 was from shocked gas in the self-intersecting tidal stream during the rising phase of a tidal disruption event, while the 2012 and 2023 emissions were from the fully formed accretion disk.}, archive = {J_ApJ}, author = {Yi-Chi Chang and Roberto Soria and Albert K. H. Kong and Alister W. Graham and Kirill A. Grishin and Igor V. Chilingarian}, doi = {10.3847/1538-4357/adbbee}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {109}, shortjournal = {The Astrophys. J.}, title = {Multiwavelength study of a hyperluminous X-ray source near NGC 6099: A strong IMBH candidate}, volume = {983}, year = {2025}, }
• (2025). Comparison of coronal hole and quiet-sun chromosphere using IRIS mg ii h and k observations of polar off-limb regions. ApJ, 983(2), 108. (www)

  @article{ , abstract = {Solar quiet regions are divided into coronal hole regions (CH) and quiet-Sun regions (QS). The global magnetic field in CH is considered open to interplanetary space, while that in QS is closed. To constrain the solar atmosphere and solar wind model, we statistically compared CH and QS in the chromosphere by quantitatively analyzing all available high-resolution spectral data sets of polar off-limb regions taken from the entire catalog of the Interface Region Imaging Spectrograph (IRIS) satellite. We extracted the characteristic quantities from the Mg ii h and k line profiles and compared the dependence of those quantities on the height from the photospheric limb. The main findings are as follows. First, the integrated intensities in the Mg ii k line show a steeper decrease with height in QS while they remain bright at higher altitudes in CH. Second, the unsigned line-of-sight velocities in the Mg ii k line generally increase with height in both regions, although the unsigned velocities increase with height more strongly in QS than in CH. Third, the Mg ii k line widths increase just above the limb and then decrease with height in both CH and QS, but are overall larger for CH than for QS, especially at the lower altitudes. Finally, we found the ratio of the Mg ii k and h lines to show a two-step increase with height in both regions. The results suggest the spicules are higher in CH, and the CH chromosphere exhibits faster motions than the QS.}, archive = {J_ApJ}, author = {Akiko Tei and Stanislav Gunár and Takenori J. Okamoto}, doi = {10.3847/1538-4357/adbc69}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {108}, shortjournal = {The Astrophys. J.}, title = {Comparison of coronal hole and quiet-sun chromosphere using IRIS mg ii h and k observations of polar off-limb regions}, volume = {983}, year = {2025}, }
• (2025). Kinetic-hybrid simulations of counterpropagating ion cyclotron waves and proton scattering in the near-sun solar wind. ApJ, 983(2), 107. (www)

  @article{ , abstract = {Ion cyclotron waves (ICWs) are prevalent in the near-Sun solar wind and play a significant role in the nonadiabatic heating of plasma. Recent observations from the Parker Solar Probe have revealed the simultaneous presence of antisunward and sunward ICWs in the vicinity of the Alfvén surface. However, single-satellite observations cannot effectively trace the generation and evolution of these observed waves. To address this limitation, we employ kinetic-hybrid simulations to replicate the generation and evolution of counterpropagating ICWs under typical plasma conditions in the near-Sun solar wind. Following the linear growth phase, the simulated waves exhibit amplitude and polarization characteristics that closely match the observations. Additionally, our simulation illustrates proton scattering induced by the counterpropagating waves. These results underscore the significance of locally generated ICWs in influencing solar wind ion dynamics.}, archive = {J_ApJ}, author = {Yifan Wu and Chen Shi and Xin Tao and Jinsong Zhao}, doi = {10.3847/1538-4357/adbc6a}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {107}, shortjournal = {The Astrophys. J.}, title = {Kinetic-hybrid simulations of counterpropagating ion cyclotron waves and proton scattering in the near-sun solar wind}, volume = {983}, year = {2025}, }
• (2025). Chaotic behavior of trapped cosmic rays. ApJ, 983(2), 106. (www)

  @article{ , abstract = {Recent experimental results on the arrival direction of high-energy cosmic rays have motivated studies to understand their propagating environment. The observed anisotropy is shaped by interstellar and local magnetic fields. In coherent magnetic structures, such as the heliosphere, or due to magnetohydrodynamic turbulence, magnetic mirroring can temporarily trap particles, leading to chaotic behavior. In this work, we develop a new method to characterize cosmic rays' chaotic behavior in magnetic systems using finite-time Lyapunov exponents. This quantity determines the degree of chaos and adapts to transitory behavior. We study particle trajectories in an axial-symmetric magnetic bottle to highlight mirroring effects. By introducing time-dependent magnetic perturbations, we study how temporal variations affect chaotic behavior. We tailor our model to the heliosphere; however, it can represent diverse magnetic configurations exhibiting mirroring phenomena. Our results have three key implications. (1) Theoretical: We find a correlation between the finite-time Lyapunov exponent and the particle escape time from the system, which follows a power law that persists even under additional perturbations. This power law may reveal intrinsic system characteristics, offering insight into propagation dynamics beyond simple diffusion. (2) Simulation: Chaotic effects play a role in cosmic-ray simulations and can influence the resulting anisotropy maps. (3) Observational: Arrival maps display areas where the chaotic properties vary significantly; these changes can be the basis for time variability in the anisotropy maps. This work lays the framework for studying the effects of magnetic mirroring of cosmic rays within the heliosphere and the role of temporal variability in the observed anisotropy.}, archive = {J_ApJ}, author = {Vanessa López-Barquero and Paolo Desiati}, doi = {10.3847/1538-4357/adbca7}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {106}, shortjournal = {The Astrophys. J.}, title = {Chaotic behavior of trapped cosmic rays}, volume = {983}, year = {2025}, }
• (2025). Magnetically assisted vorticity production in decaying acoustic turbulence. ApJ, 983(2), 105. (www)

  @article{ , abstract = {We study vorticity production in isothermal, subsonic, acoustic (nonvortical), and decaying turbulence due to the presence of magnetic fields. Using three-dimensional numerical simulations, we find that the resulting kinetic energy cascade follows the ordinary Kolmogorov phenomenology involving a constant spectral energy flux. The nondimensional prefactor for acoustic turbulence is larger than the standard Kolmogorov constant due to the inefficient dissipation of kinetic energy. We also find that the Lorentz force can drive vortical motions even when the initial field is uniform by converting a fraction of the acoustic energy into vortical energy. This conversion is shown to be quadratic in the magnetic field strength and linear in the acoustic flow speed. By contrast, the direct production of vortical motions by a non-force-free magnetic field is linear in the field strength. Our results suggest that magnetic fields play a crucial role in vorticity production in cosmological flows, particularly in scenarios where significant acoustic turbulence is prevalent. We also discuss the implications of our findings for the early Universe, where magnetic fields may convert acoustic turbulence generated during cosmological phase transitions into vortical turbulence.}, archive = {J_ApJ}, author = {Axel Brandenburg and Evan Scannapieco}, doi = {10.3847/1538-4357/adbe38}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {105}, shortjournal = {The Astrophys. J.}, title = {Magnetically assisted vorticity production in decaying acoustic turbulence}, volume = {983}, year = {2025}, }
• (2025). OGLE-2011-BLG-0462: An isolated stellar-mass black hole confirmed using new HST astrometry and updated photometry. ApJ, 983(2), 104. (www)

  @article{ , abstract = {The long-duration Galactic-bulge microlensing event OGLE-2011-BLG-0462 produced relativistic astrometric deflections of the source star, which we measured using Hubble Space Telescope (HST) observations taken at eight epochs over ∼6 yr. Analysis of the microlensing light curve and astrometry led our group (followed by other independent groups) to conclude that the lens is an isolated stellar-mass black hole (BH)—the first and only one unambiguously discovered to date. There have now been three additional epochs of HST observations, increasing the astrometric time baseline to 11 yr. Additionally, the ground-based OGLE data have been updated. We have reanalyzed the data, including the new HST astrometry, and photometry obtained with 16 different telescopes. The source lies only 0\mathop{.}\limits^{^{\prime\prime} }4 from a bright neighbor, making it crucial to perform precise subtraction of its point-spread function (PSF) in the astrometric measurements of the source. Moreover, we show that it is essential to perform a separate PSF subtraction for each individual HST frame as part of the reductions. Our final solution yields a lens mass of 7.15 ± 0.83 M ⊙ . Combined with the lack of detected light from the lens at late HST epochs, the BH nature of the lens is conclusively verified. The BH lies at a distance of 1.52 ± 0.15 kpc, and it is moving with a space velocity of 51.1 ± 7.5 km s −1 relative to the stars in the neighborhood. We compare our results with those of other studies and discuss reasons for the differences. We also searched for binary companions of the BH at a range of separations, but found no evidence for any.}, archive = {J_ApJ}, author = {Kailash C. Sahu and Jay Anderson and Stefano Casertano and Howard E. Bond and Martin Dominik and Annalisa Calamida and Andrea Bellini and Thomas M. Brown and Henry C. Ferguson and Marina Rejkuba}, doi = {10.3847/1538-4357/adbe6e}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {104}, shortjournal = {The Astrophys. J.}, title = {OGLE-2011-BLG-0462: An isolated stellar-mass black hole confirmed using new HST astrometry and updated photometry}, volume = {983}, year = {2025}, }
• (2025). Linking critical heights in solar active regions with 3D coronal mass ejection speeds: Insights from automated and manual polarity inversion line detection methods. ApJ, 983(2), 103. (www)

  @article{ , abstract = {In a space weather context, the most geoeffective coronal mass ejections (CMEs) are fast CMEs from Earth-facing solar active regions. These CMEs are difficult to characterize in coronagraph data due to their high speed (fewer observations), faintness, Earthward orientation (halo CMEs), and disruptions from associated high-energy particle storms. Any diagnostic aiding in early CME speed identification is valuable. This study investigates whether the 3D speeds of 37 CMEs are correlated with the critical heights of their source regions, to test the hypothesis that if the critical height is located at a higher altitude in the corona, the weaker magnetic field environment will enable a faster CME to be produced. Critical heights near CME onset are calculated by identifying polarity inversion lines (PIL) in magnetogram data using automated and manual methods. 3D speeds are determined by fitting a Graduated Cylindrical Shell model to multiviewpoint coronagraph images. For the automated method, we find a high correlation of 71% ± 8% between CME speed and critical height, dropping to 48% ± 12% when using CME plane-of-sky speeds, on which most previous similar studies are based. An attempt to improve the critical height diagnostic through manual PIL selection yields a lower correlation of 58% ± 13%. The higher correlation from the automated method suggests that encompassing the full PIL structure is a better measure of the magnetic conditions that influence CME dynamics. Our results highlight the potential for critical height as a continuously computable diagnostic for forecasting the 3D speeds of Earth-directed CMEs.}, archive = {J_ApJ}, author = {Harshita Gandhi and Alexander W James and Huw Morgan and Lucie Green}, doi = {10.3847/1538-4357/adbf09}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {103}, shortjournal = {The Astrophys. J.}, title = {Linking critical heights in solar active regions with 3D coronal mass ejection speeds: Insights from automated and manual polarity inversion line detection methods}, volume = {983}, year = {2025}, }
• (2025). Revealing the CME impact on the martian nightside ionosphere based on MAVEN and tianwen-1 observations. ApJ, 983(2), 102. (www)

  @article{ , abstract = {Due to the absence of an Earth-like dipole magnetic field, the impact of coronal mass ejections (CMEs) on the Martian nightside ionosphere differs from that on Earth and is still not well understood. This study investigates the responses in the Martian nightside ionosphere to a CME event that occurred on 2022 August 30 using observations from Tianwen-1 and Mars Atmosphere and Volatile EvolutioN. The ion density in the upper Martian nightside ionosphere between 200 and 500 km decreases when two successive CMEs hit the induced Martian magnetosphere, with a brief density recovery between the two CMEs. This suggests that ion density in the Martian nightside ionosphere between 200 and 500 km decreases as the intensity of CMEs increases. The primary cause of the observed decrease in the nightside ion density is likely due to the enhanced magnetic field pressure above the Martian ionosphere during CMEs, which facilitates ion escape from the dayside ionosphere; this subsequently reduces the amount of ions transported to the nightside ionosphere, thereby leading to a decrease in ion density on nightside. Furthermore, hemispheric asymmetry is found in the ionospheric response, indicating that the crustal magnetic fields in the southern hemisphere may play a role in slowing down the reduction of ion density. This study expands the comprehensive description of the impact of a CME event on different regions of Mars and its underlying mechanisms.}, archive = {J_ApJ}, author = {Longhui Liu and Xinzhi Qiu and Yiqun Yu and Wudi Luo and Xin Wang and Jinbin Cao and Cunhui Li and YuMing Wang and TieLong Zhang}, doi = {10.3847/1538-4357/adbf8b}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {102}, shortjournal = {The Astrophys. J.}, title = {Revealing the CME impact on the martian nightside ionosphere based on MAVEN and tianwen-1 observations}, volume = {983}, year = {2025}, }
• (2025). A multiwavelength autopsy of the interacting type IIn supernova 2020ywx: Tracing its progenitor mass-loss history for 100 yr before death. ApJ, 983(2), 101. (www)

  @article{ , abstract = {While the subclass of interacting supernovae (SNe) with narrow hydrogen emission lines (Type IIn supernovae (SNe IIn)) consists of some of the longest-lasting and brightest supernovae (SNe) ever discovered, their progenitors are still not well understood. Investigating SNe IIn as they emit across the electromagnetic spectrum is the most robust way to understand the progenitor evolution before the explosion. This work presents X-ray, optical, infrared, and radio observations of the strongly interacting Type IIn supernova, SN 2020ywx, covering a period >1200 days after discovery. Through multiwavelength modeling, we find that the progenitor of 2020ywx was losing mass at ∼10 −2 –10 −3 M ⊙ yr −1 for at least 100 yr pre-explosion using the circumstellar medium (CSM) speed of 120 km s −1 measured from optical and near-infrared (NIR) spectra. Despite the similar magnitude of mass loss measured in different wavelength ranges, we find discrepancies between the X-ray and optical/radio-derived mass-loss evolution, which suggest asymmetries in the CSM. Furthermore, we find evidence for dust formation due to the combination of a growing blueshift in optical emission lines and NIR continuum emission which we fit with blackbodies at ∼1000 K. Based on the observed elevated mass loss over more than 100 yr and the configuration of the CSM inferred from the multiwavelength observations, we invoke binary interaction as the most plausible mechanism to explain the overall mass-loss evolution. SN 2020ywx is thus a case that may support the growing observational consensus that SNe IIn mass loss is explained by binary interaction.}, archive = {J_ApJ}, author = {Raphael Baer-Way and Poonam Chandra and Maryam Modjaz and Sahana Kumar and Craig Pellegrino and Roger Chevalier and Adrian Crawford and Arkaprabha Sarangi and Nathan Smith and Keiichi Maeda and Nayana A. J. and Alexei V. Filippenko and Jennifer E. Andrews and Iair Arcavi and K. Azalee Bostroem and Thomas G. Brink and Yize Dong and Vikram Dwarkadas and Joseph R. Farah and D. Andrew Howell and Daichi Hiramatsu and Griffin Hosseinzadeh and Curtis McCully and Nicolas Meza and Megan Newsome and Estefania Padilla Gonzalez and Jeniveve Pearson and David J. Sand and Manisha Shrestha and Giacomo Terreran and Stefano Valenti and Samuel Wyatt and Yi Yang and WeiKang Zheng}, doi = {10.3847/1538-4357/adc00a}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {101}, shortjournal = {The Astrophys. J.}, title = {A multiwavelength autopsy of the interacting type IIn supernova 2020ywx: Tracing its progenitor mass-loss history for 100 yr before death}, volume = {983}, year = {2025}, }
• (2025). Cosmic filament spin. II. filament spin and its impact on galaxy Spin–Filament alignment in a cosmological simulation. ApJ, 983(2), 100. (www)

  @article{ , abstract = {Observational studies have reported that cosmic filaments on the megaparsec scale exhibit rotational motion. Subsequent simulation studies have shown qualitative agreement with these findings, but quantitative discrepancies remain due to differences in data and methods, which require verification. To address this issue, we adopt the same methodology as used in the observations to identify filament spin from the galaxy distribution constructed from a hydrodynamic simulation. Using the same approach to measure filament spin, we find that the simulation results closely match the observational findings, with only minor discrepancies arising from slight differences in the fraction of filaments classified as dynamically cold or hot based on their dynamic temperature. Additionally, an analysis of how filament spin affects the galaxy spin–filament correlation shows that dynamically cold filaments with strong spin signals have a greater impact on the galaxy spin–filament correlation than those with weaker spin signals and dynamically hot filaments. These results not only provide further evidence that cosmic filaments exhibit spin but also highlight the importance of this rotation in the acquisition of angular momentum by individual galaxies. Future studies exploring the influence of filament spin on galaxy spin may shed light on the physical origins of filaments and the angular momentum of galaxies.}, archive = {J_ApJ}, author = {Peng Wang and Xiao-xiao Tang and Hao-da Wang and Noam I. Libeskind and Elmo Tempel and Wei Wang and Youcai Zhang and Ming-Jie Sheng and Hao-Ran Yu and Haojie Xu}, doi = {10.3847/1538-4357/adc0a2}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {100}, shortjournal = {The Astrophys. J.}, title = {Cosmic filament spin. II. filament spin and its impact on galaxy Spin–Filament alignment in a cosmological simulation}, volume = {983}, year = {2025}, }
• (2025). Search for continuous gravitational waves from known pulsars in the first part of the fourth LIGO-virgo-KAGRA observing run. ApJ, 983(2), 99. (www)

  @article{ , abstract = {Continuous gravitational waves (CWs) emission from neutron stars carries information about their internal structure and equation of state, and it can provide tests of general relativity. We present a search for CWs from a set of 45 known pulsars in the first part of the fourth LIGO–Virgo–KAGRA observing run, known as O4a. We conducted a targeted search for each pulsar using three independent analysis methods considering single-harmonic and dual-harmonic emission models. We find no evidence of a CW signal in O4a data for both models and set upper limits on the signal amplitude and on the ellipticity, which quantifies the asymmetry in the neutron star mass distribution. For the single-harmonic emission model, 29 targets have the upper limit on the amplitude below the theoretical spin-down limit. The lowest upper limit on the amplitude is 6.4 × 10 −27 for the young energetic pulsar J0537−6910, while the lowest constraint on the ellipticity is 8.8 × 10 −9 for the bright nearby millisecond pulsar J0437−4715. Additionally, for a subset of 16 targets, we performed a narrowband search that is more robust regarding the emission model, with no evidence of a signal. We also found no evidence of nonstandard polarizations as predicted by the Brans–Dicke theory.}, archive = {J_ApJ}, author = {A. G. Abac and R. Abbott and I. Abouelfettouh and F. Acernese and K. Ackley and S. Adhicary and N. Adhikari and R. X. Adhikari and V. K. Adkins and D. Agarwal and M. Agathos and M. Aghaei Abchouyeh and O. D. Aguiar and I. Aguilar and L. Aiello and A. Ain and P. Ajith and T. Akutsu and S. Albanesi and R. A. Alfaidi and A. Al-Jodah and C. Alléné and A. Allocca and S. Al-Shammari and P. A. Altin and S. Alvarez-Lopez and A. Amato and L. Amez-Droz and A. Amorosi and C. Amra and A. Ananyeva and S. B. Anderson and W. G. Anderson and M. Andia and M. Ando and T. Andrade and N. Andres and M. Andrés-Carcasona and T. Andrić and J. Anglin and S. Ansoldi and J. M. Antelis and S. Antier and M. Aoumi and E. Z. Appavuravther and S. Appert and S. K. Apple and K. Arai and A. Araya and M. C. Araya and J. S. Areeda and L. Argianas and N. Aritomi and F. Armato and N. Arnaud and M. Arogeti and S. M. Aronson and G. Ashton and Y. Aso and M. Assiduo and S. Assis de Souza Melo and S. M. Aston and P. Astone and F. Attadio and F. Aubin and K. AultONeal and G. Avallone and S. Babak and F. Badaracco and C. Badger and S. Bae and S. Bagnasco and E. Bagui and J. G. Baier and L. Baiotti and R. Bajpai and T. Baka and M. Ball and G. Ballardin and S. W. Ballmer and S. Banagiri and B. Banerjee and D. Bankar and P. Baral and J. C. Barayoga and B. C. Barish and D. Barker and P. Barneo and F. Barone and B. Barr and L. Barsotti and M. Barsuglia and D. Barta and A. M. Bartoletti and M. A. Barton and I. Bartos and S. Basak and A. Basalaev and R. Bassiri and A. Basti and D. E. Bates and M. Bawaj and P. Baxi and J. C. Bayley and A. C. Baylor and P. A. Baynard II and M. Bazzan and V. M. Bedakihale and F. Beirnaert and M. Bejger and D. Belardinelli and A. S. Bell and V. Benedetto and W. Benoit and J. D. Bentley and M. Ben Yaala and S. Bera and M. Berbel and F. Bergamin and B. K. Berger and S. Bernuzzi and M. Beroiz and D. Bersanetti and A. Bertolini and J. Betzwieser and D. Beveridge and N. Bevins and R. Bhandare and U. Bhardwaj and R. Bhatt and D. Bhattacharjee and S. Bhaumik and S. Bhowmick and A. Bianchi and I. A. Bilenko and G. Billingsley and A. Binetti and S. Bini and O. Birnholtz and S. Biscoveanu and A. Bisht and M. Bitossi and M.-A. Bizouard and J. K. Blackburn and L. A. Blagg and C. D. Blair and D. G. Blair and F. Bobba and N. Bode and G. Boileau and M. Boldrini and G. N. Bolingbroke and A. Bolliand and L. D. Bonavena and R. Bondarescu and F. Bondu and E. Bonilla and M. S. Bonilla and A. Bonino and R. Bonnand and P. Booker and A. Borchers and V. Boschi and S. Bose and V. Bossilkov and V. Boudart and A. Boudon and A. Bozzi and C. Bradaschia and P. R. Brady and M. Braglia and A. Branch and M. Branchesi and J. Brandt and I. Braun and M. Breschi and T. Briant and A. Brillet and M. Brinkmann and P. Brockill and E. Brockmueller and A. F. Brooks and B. C. Brown and D. D. Brown and M. L. Brozzetti and S. Brunett and G. Bruno and R. Bruntz and J. Bryant and F. Bucci and J. Buchanan and O. Bulashenko and T. Bulik and H. J. Bulten and A. Buonanno and K. Burtnyk and R. Buscicchio and D. Buskulic and C. Buy and R. L. Byer and G. S. Cabourn Davies and G. Cabras and R. Cabrita and V. Cáceres-Barbosa and L. Cadonati and G. Cagnoli and C. Cahillane and J. Calderón Bustillo and T. A. Callister and E. Calloni and J. B. Camp and M. Canepa and G. Caneva Santoro and K. C. Cannon and H. Cao and L. A. Capistran and E. Capocasa and E. Capote and G. Carapella and F. Carbognani and M. Carlassara and J. B. Carlin and M. Carpinelli and G. Carrillo and J. J. Carter and G. Carullo and J. Casanueva Diaz and C. Casentini and S. Y. Castro-Lucas and S. Caudill and M. Cavaglià and R. Cavalieri and G. Cella and P. Cerdá-Durán and E. Cesarini and W. Chaibi and P. Chakraborty and S. Chalathadka Subrahmanya and J. C. L. Chan and M. Chan and K. Chandra and R.-J. Chang and S. Chao and E. L. Charlton and P. Charlton and E. Chassande-Mottin and C. Chatterjee and Debarati Chatterjee and Deep Chatterjee and M. Chaturvedi and S. Chaty and A. Chen and A. H.-Y. Chen and D. Chen and H. Chen and H. Y. Chen and J. Chen and K. H. Chen and Y. Chen and Yanbei Chen and Yitian Chen and H. P. Cheng and P. Chessa and H. T. Cheung and S. Y. Cheung and F. Chiadini and G. Chiarini and R. Chierici and A. Chincarini and M. L. Chiofalo and A. Chiummo and C. Chou and S. Choudhary and N. Christensen and S. S. Y. Chua and P. Chugh and G. Ciani and P. Ciecielag and M. Cieślar and M. Cifaldi and R. Ciolfi and F. Clara and J. A. Clark and J. Clarke and T. A. Clarke and P. Clearwater and S. Clesse and E. Coccia and E. Codazzo and P.-F. Cohadon and S. Colace and M. Colleoni and C. G. Collette and J. Collins and S. Colloms and A. Colombo and M. Colpi and C. M. Compton and G. Connolly and L. Conti and T. R. Corbitt and I. Cordero-Carrión and S. Corezzi and N. J. Cornish and A. Corsi and S. Cortese and C. A. Costa and R. Cottingham and M. W. Coughlin and A. Couineaux and J.-P. Coulon and S. T. Countryman and J.-F. Coupechoux and P. Couvares and D. M. Coward and M. J. Cowart and R. Coyne and K. Craig and R. Creed and J. D. E. Creighton and T. D. Creighton and P. Cremonese and A. W. Criswell and J. C. G. Crockett-Gray and S. Crook and R. Crouch and J. Csizmazia and J. R. Cudell and T. J. Cullen and A. Cumming and E. Cuoco and M. Cusinato and P. Dabadie and T. Dal Canton and S. Dall’Osso and S. Dal Pra and G. Dálya and B. D’Angelo and S. Danilishin and S. D’Antonio and K. Danzmann and K. E. Darroch and L. P. Dartez and A. Dasgupta and S. Datta and V. Dattilo and A. Daumas and N. Davari and I. Dave and A. Davenport and M. Davier and T. F. Davies and D. Davis and L. Davis and M. C. Davis and P. J. Davis and M. Dax and J. De Bolle and M. Deenadayalan and J. Degallaix and M. De Laurentis and S. Deléglise and F. De Lillo and D. Dell’Aquila and W. Del Pozzo and F. De Marco and F. De Matteis and V. D’Emilio and N. Demos and T. Dent and A. Depasse and N. DePergola and R. De Pietri and R. De Rosa and C. De Rossi and R. DeSalvo and R. De Simone and A. Dhani and R. Diab and M. C. Díaz and M. Di Cesare and G. Dideron and N. A. Didio and T. Dietrich and L. Di Fiore and C. Di Fronzo and M. Di Giovanni and T. Di Girolamo and D. Diksha and A. Di Michele and J. Ding and S. Di Pace and I. Di Palma and F. Di Renzo and Divyajyoti and A. Dmitriev and Z. Doctor and E. Dohmen and P. P. Doleva and D. Dominguez and L. D’Onofrio and F. Donovan and K. L. Dooley and T. Dooney and S. Doravari and O. Dorosh and M. Drago and J. C. Driggers and J.-G. Ducoin and L. Dunn and U. Dupletsa and D. D’Urso and H. Duval and P.-A. Duverne and S. E. Dwyer and C. Eassa and M. Ebersold and T. Eckhardt and G. Eddolls and B. Edelman and T. B. Edo and O. Edy and A. Effler and J. Eichholz and H. Einsle and M. Eisenmann and R. A. Eisenstein and A. Ejlli and R. M. Eleveld and M. Emma and K. Endo and A. J. Engl and E. Enloe and L. Errico and R. C. Essick and H. Estellés and D. Estevez and T. Etzel and M. Evans and T. Evstafyeva and B. E. Ewing and J. M. Ezquiaga and F. Fabrizi and F. Faedi and V. Fafone and S. Fairhurst and A. M. Farah and B. Farr and W. M. Farr and G. Favaro and M. Favata and M. Fays and M. Fazio and J. Feicht and M. M. Fejer and R. Felicetti and E. Fenyvesi and D. L. Ferguson and S. Ferraiuolo and I. Ferrante and T. A. Ferreira and F. Fidecaro and P. Figura and A. Fiori and I. Fiori and M. Fishbach and R. P. Fisher and R. Fittipaldi and V. Fiumara and R. Flaminio and S. M. Fleischer and L. S. Fleming and E. Floden and E. M. Foley and H. Fong and J. A. Font and B. Fornal and P. W. F. Forsyth and K. Franceschetti and N. Franchini and S. Frasca and F. Frasconi and A. Frattale Mascioli and Z. Frei and A. Freise and O. Freitas and R. Frey and W. Frischhertz and P. Fritschel and V. V. Frolov and G. G. Fronzé and M. Fuentes-Garcia and S. Fujii and T. Fujimori and P. Fulda and M. Fyffe and B. Gadre and J. R. Gair and S. Galaudage and V. Galdi and H. Gallagher and S. Gallardo and B. Gallego and R. Gamba and A. Gamboa and D. Ganapathy and A. Ganguly and B. Garaventa and J. García-Bellido and C. García Núñez and C. García-Quirós and J. W. Gardner and K. A. Gardner and J. Gargiulo and A. Garron and F. Garufi and C. Gasbarra and B. Gateley and V. Gayathri and G. Gemme and A. Gennai and V. Gennari and J. George and R. George and O. Gerberding and L. Gergely and Archisman Ghosh and Sayantan Ghosh and Shaon Ghosh and Shrobana Ghosh and Suprovo Ghosh and Tathagata Ghosh and L. Giacoppo and J. A. Giaime and K. D. Giardina and D. R. Gibson and D. T. Gibson and C. Gier and P. Giri and F. Gissi and S. Gkaitatzis and J. Glanzer and F. Glotin and J. Godfrey and P. Godwin and N. L. Goebbels and E. Goetz and J. Golomb and S. Gomez Lopez and B. Goncharov and Y. Gong and G. González and P. Goodarzi and S. Goode and A. W. Goodwin-Jones and M. Gosselin and A. S. Göttel and R. Gouaty and D. W. Gould and K. Govorkova and S. Goyal and B. Grace and A. Grado and V. Graham and A. E. Granados and M. Granata and V. Granata and S. Gras and P. Grassia and A. Gray and C. Gray and R. Gray and G. Greco and A. C. Green and S. M. Green and S. R. Green and A. M. Gretarsson and E. M. Gretarsson and D. Griffith and W. L. Griffiths and H. L. Griggs and G. Grignani and A. Grimaldi and C. Grimaud and H. Grote and D. Guerra and D. Guetta and G. M. Guidi and A. R. 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Heurs and A. L. Hewitt and J. Heyns and S. Higginbotham and S. Hild and S. Hill and Y. Himemoto and N. Hirata and C. Hirose and W. C. G. Ho and S. Hoang and S. Hochheim and D. Hofman and N. A. Holland and K. Holley-Bockelmann and Z. J. Holmes and D. E. Holz and L. Honet and C. Hong and J. Hornung and S. Hoshino and J. Hough and S. Hourihane and E. J. Howell and C. G. Hoy and C. A. Hrishikesh and H.-F. Hsieh and C. Hsiung and H. C. Hsu and W.-F. Hsu and P. Hu and Q. Hu and H. Y. Huang and Y.-J. Huang and A. D. Huddart and B. Hughey and D. C. Y. Hui and V. Hui and S. Husa and R. Huxford and T. Huynh-Dinh and L. Iampieri and G. A. Iandolo and M. Ianni and A. Iess and H. Imafuku and K. Inayoshi and Y. Inoue and G. Iorio and M. H. Iqbal and J. Irwin and R. Ishikawa and M. Isi and M. A. Ismail and Y. Itoh and H. Iwanaga and M. Iwaya and B. R. Iyer and V. JaberianHamedan and C. Jacquet and P.-E. Jacquet and S. J. Jadhav and S. P. Jadhav and T. Jain and A. L. James and P. A. James and R. 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Vitale and A. Vives and H. Vocca and D. Voigt and E. R. G. von Reis and J. S. A. von Wrangel and S. P. Vyatchanin and L. E. Wade and M. Wade and K. J. Wagner and A. Wajid and M. Walker and G. S. Wallace and L. Wallace and H. Wang and J. Z. Wang and W. H. Wang and Z. Wang and G. Waratkar and J. Warner and M. Was and T. Washimi and N. Y. Washington and D. Watarai and K. E. Wayt and B. R. Weaver and B. Weaver and C. R. Weaving and S. A. Webster and M. Weinert and A. J. Weinstein and R. Weiss and F. Wellmann and L. Wen and P. Wessels and K. Wette and J. T. Whelan and B. F. Whiting and C. Whittle and J. B. Wildberger and O. S. Wilk and D. Wilken and A. T. Wilkin and D. J. Willadsen and K. Willetts and D. Williams and M. J. Williams and N. S. Williams and J. L. Willis and B. Willke and M. Wils and J. Winterflood and C. C. Wipf and G. Woan and J. Woehler and J. K. Wofford and N. E. Wolfe and H. T. Wong and H. W. Y. Wong and I. C. F. Wong and J. L. Wright and M. Wright and C. Wu and D. S. Wu and H. Wu and E. Wuchner and D. M. Wysocki and V. A. Xu and Y. Xu and N. Yadav and H. Yamamoto and K. Yamamoto and T. S. Yamamoto and T. Yamamoto and S. Yamamura and R. Yamazaki and S. Yan and T. Yan and F. W. Yang and F. Yang and K. Z. Yang and Y. Yang and Z. Yarbrough and H. Yasui and S.-W. Yeh and A. B. Yelikar and X. Yin and J. Yokoyama and T. Yokozawa and J. Yoo and H. Yu and S. Yuan and H. Yuzurihara and A. Zadrożny and M. Zanolin and M. Zeeshan and T. Zelenova and J.-P. Zendri and M. Zeoli and M. Zerrad and M. Zevin and A. C. Zhang and L. Zhang and R. Zhang and T. Zhang and Y. Zhang and C. Zhao and Yue Zhao and Yuhang Zhao and Y. Zheng and H. Zhong and R. Zhou and X.-J. Zhu and Z.-H. Zhu and A. B. Zimmerman and M. E. Zucker and J. Zweizig and S. B. Araujo Furlan and Z. Arzoumanian and A. Basu and A. Cassity and I. Cognard and K. Crowter and S. del Palacio and C. M. Espinoza and E. Fonseca and C. M. L. Flynn and G. Gancio and F. García and K. C. Gendreau and D. C. Good and L. Guillemot and S. Guillot and M. J. Keith and L. Kuiper and M. E. Lower and A. G. Lyne and J. W. McKee and B. W. Meyers and J. L. Palfreyman and A. B. Pearlman and G. E. Romero and R. M. Shannon and B. Shaw and I. H. Stairs and B. W. Stappers and C. M. Tan and G. Theureau and M. Thompson and P. Weltevrede and E. Zubieta}, doi = {10.3847/1538-4357/adb3a0}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {99}, shortjournal = {The Astrophys. J.}, title = {Search for continuous gravitational waves from known pulsars in the first part of the fourth LIGO-virgo-KAGRA observing run}, volume = {983}, year = {2025}, }
• (2025). The JWST view of cygnus a: Jet-driven coronal outflow with a twist. ApJ, 983(2), 98. (www)

  @article{ , abstract = {We present first results from James Webb Space Telescope Near-Infrared Spectrograph, Mid-Infrared Instrument, and Keck Cosmic Webb Imager integral field spectroscopy of the powerful but highly obscured host galaxy of the jetted radio source Cygnus A. We detect 169 infrared emission lines at 1.7–27 μ m and explore the kinematics and physical properties of the extended narrow-line region (NLR) in unprecedented detail. The density-stratified NLR appears to be shaped by the initial blow-out and ongoing interaction of the radio jet with the interstellar medium, creating a multiphase bicone with a layered structure composed of molecular and ionized gas. The NLR spectrum, with strong coronal emission at kiloparsec scale, is well modeled by active galactic nucleus photoionization. We find evidence that the NLR is rotating around the radio axis, perhaps mediated by magnetic fields and driven by angular momentum transfer from the radio jet. The overall velocity field of the NLR is well described by 250 km s −1 outflow along biconical spiral flow lines, combining both rotation and outflow signatures. There is particularly bright [Fe ii ] λ 1.644 μ m emission from a dense, high-velocity dispersion, photoionized clump of clouds found near the projected radio axis. Outflows of 600–2000 km s −1 are found in bullets and streamers of ionized gas that may be ablated by the radio jet from these clouds, driving a local outflow rate of 40 M ⊙ yr −1 .}, archive = {J_ApJ}, author = {Patrick M. Ogle and B. Sebastian and A. Aravindan and M. McDonald and G. Canalizo and M. L. N. Ashby and M. Azadi and R. Antonucci and P. Barthel and S. Baum and M. Birkinshaw and C. Carilli and M. Chiaberge and C. Duggal and K. Gebhardt and S. Hyman and J. Kuraszkiewicz and E. Lopez-Rodriguez and A. M. Medling and G. Miley and O. Omoruyi and C. O’Dea and D. Perley and R. A. Perley and E. Perlman and V. Reynaldi and M. Singha and W. Sparks and G. Tremblay and B. J. Wilkes and S. P. Willner and D. M. Worrall}, doi = {10.3847/1538-4357/adb71a}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {98}, shortjournal = {The Astrophys. J.}, title = {The JWST view of cygnus a: Jet-driven coronal outflow with a twist}, volume = {983}, year = {2025}, }
• (2025). An oxidation gradient straddling the small planet radius valley. ApJ, 983(2), 97. (www)

  @article{ , abstract = {We present a population-level view of volatile gas species (H 2 , He, H 2 O, O 2 , CO, CO 2 , CH 4 ) distribution during the sub-Neptune to rocky planet transition, revealing in detail the dynamic nature of small planet atmospheric compositions. Our novel model couples the atmospheric escape model IsoFATE with the magma ocean-atmosphere equilibrium chemistry model Atmodeller to simulate interior-atmosphere evolution over time for sub-Neptunes around G, K, and M stars. Chiefly, our simulations reveal that atmospheric mass fractionation driven by escape and interior-atmosphere exchange conspire to create a distinct oxidation gradient straddling the small-planet radius valley. We discover a key mechanism in shaping the oxidation landscape is the dissolution of water into the molten mantle, which shields oxygen from early escape, buffers the escape rate, and leads to oxidized secondary atmospheres following mantle outgassing. Our simulations reproduce a prominent population of He-rich worlds along the upper edge of the radius valley, revealing that they are stable on shorter timescales than previously predicted. Our simulations also robustly predict a broad population of O 2 -dominated atmospheres on close-in planets around low-mass stars, posing a potential source of false positive biosignature detection and marking a high-priority opportunity for the first-ever atmospheric O 2 detection. We motivate future atmospheric characterization surveys by providing a target list of planet candidates predicted to have O 2 -, He-, and deuterium-rich atmospheres.}, archive = {J_ApJ}, author = {Collin Cherubim and Robin Wordsworth and Dan J. Bower and Paolo A. Sossi and Danica Adams and Renyu Hu}, doi = {10.3847/1538-4357/adbca9}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {97}, shortjournal = {The Astrophys. J.}, title = {An oxidation gradient straddling the small planet radius valley}, volume = {983}, year = {2025}, }
• (2025). The detection of H2O maser emission from mid-IR red galaxies. ApJ, 983(2), 96. (www)

  @article{ , abstract = {We report the detection of H 2 O maser emission in 4 out of 77 (5.2%) mid-IR red galaxies that meet the color criteria of W 1 − W 2 > 0.5 and W 1 − W 4 > 7 and are classified as Type 2 active galactic nuclei (AGNs) based on optical, near-IR, and mid-IR spectral energy distribution (SED) fitting. Here, W 1, W 2, and W 4 represent the IR magnitudes at 3.4, 4.6, and 22 μ m, respectively, as measured by the Wide-field Infrared Survey Explorer. Three of the four newly identified maser galaxies are classified as either Seyfert 2 or low-ionization nuclear emission-line region systems, but none are disk maser systems. Our analysis indicates that AGN identifications based solely on SED fitting are unreliable, resulting in an unexpectedly low megamaser detection rate. By restricting our sample to optically classified Type 2 AGNs that satisfy the mid-IR color criteria, we achieve a maser detection rate of ∼13%–18%, aligning with previous predictions for mid-IR red sources. These selection criteria are one of the most effective methods to date for facilitating new maser detections, particularly in light of the recent identification of additional Type 2 AGNs identified from ongoing galaxy and AGN surveys.}, archive = {J_ApJ}, author = {C. Y. Kuo and C. Y. Tai and A. Constantin and J. A. Braatz and H. H. Chung and B. Y. Chen and D. W. Pesce and C. M. V. Impellizzeri and F. Gao and Y.-Y. Chang}, doi = {10.3847/1538-4357/adbe3a}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {96}, shortjournal = {The Astrophys. J.}, title = {The detection of H2O maser emission from mid-IR red galaxies}, volume = {983}, year = {2025}, }
• (2025). OMEGACat. VI. analysis of the overall kinematics of omega centauri in 3D: Velocity dispersion, kinematic distance, anisotropy, and energy equipartition. ApJ, 983(2), 95. (www)

  @article{ , abstract = {Omega Centauri ( ω Cen) is the Milky Way's most massive globular cluster and is likely the stripped nucleus of an accreted dwarf galaxy. In this paper, we analyze ω Cen's kinematics using data from oMEGACat, a comprehensive catalog of ω Cen's central regions, including 1.4 million proper motion measurements and 300,000 spectroscopic radial velocities. Our velocity dispersion profiles and kinematic maps are consistent with previous work but improve on their resolution, precision, and spatial coverage. The cluster's 3D dispersion is isotropic in the core, with increasing radial anisotropy at larger radii. The 2D kinematic maps show an elongation of the velocity dispersion field comparable to the flattening observed photometrically. We find good agreement between proper motions and line-of-sight velocity dispersion, and we measure a kinematic distance of 5494 ± 61 pc, the most precise kinematic distance to ω Cen available. The subset of data with precise metallicity measurements shows no correlation between metallicity and kinematics, supporting the picture of well-mixed stellar populations within the half-light radius of ω Cen. Finally, we study the degree of energy equipartition using a large range of stellar masses. We find partial energy equipartition in the center that decreases towards large radii. The spatial dependence of the radial energy equipartition is stronger than the tangential energy equipartition. Our kinematic observations can serve as a new reference for future dynamical modeling efforts that will help to further disentangle the complex mass distribution within ω Cen.}, archive = {J_ApJ}, author = {Maximilian Häberle and N. Neumayer and C. Clontz and A. C. Seth and P. J. Smith and S. Kamann and R. Pechetti and M. S. Nitschai and M. Alfaro-Cuello and H. Baumgardt and A. Bellini and A. Feldmeier-Krause and N. Kacharov and M. Libralato and A. P. Milone and S. O. Souza and G. van de Ven and Z. Wang}, doi = {10.3847/1538-4357/adbe67}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {95}, shortjournal = {The Astrophys. J.}, title = {OMEGACat. VI. analysis of the overall kinematics of omega centauri in 3D: Velocity dispersion, kinematic distance, anisotropy, and energy equipartition}, volume = {983}, year = {2025}, }
• (2025). Are purely gaseous bars in dwarf irregulars a myth?. ApJ, 983(2), 94. (www)

  @article{ , abstract = {About two-thirds of galactic disks exhibit a central ellipsoidal stellar component called the bar, with or without a gaseous counterpart. However, there are a few dwarf galaxies with purely gaseous bars: NGC 3741, NGC 2915, and DDO 168. This is a puzzle, as gas is a collisional medium, and a gaseous bar is expected to be ripped off by shock waves. We study the formation of gaseous bars in these galaxies by constructing dynamical models constrained by stellar photometry and H i observations already available. We first analytically study the dynamical stability of the galactic disks against global m = 2 perturbations. Our results indicate that the stellar and gas disks are moderately unstable against these bar modes. Using N -body + hydrodynamical simulations employing RAMSES, we next find that a purely gaseous bar is formed in an oblate dark matter halo of vertical-to-planar axis ratio c / a = 0.6–0.8, with a relatively high-spin parameter Λ = 0.04–0.07, which survives for more than 10 dynamical times. Further, the low values of our calculated Mach numbers M = 2–6 of the gaseous medium comply with the survival of the gaseous bars, unaffected by shock waves. Interestingly, our simulations show the formation of a tiny stellar bar in each case. However, the temporal evolution of the change in angular momentum L z of the different disk components indicates the exchange of L z between the gas disk and the dark matter halo only; the L z of the stellar disk remained unchanged, indicating a weak stellar bar.}, archive = {J_ApJ}, author = {Anagha A. G. and Arunima Banerjee}, doi = {10.3847/1538-4357/adbf00}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {94}, shortjournal = {The Astrophys. J.}, title = {Are purely gaseous bars in dwarf irregulars a myth?}, volume = {983}, year = {2025}, }
• (2025). Effects of galactic environment on size and dark matter content in low-mass galaxies. ApJ, 983(2), 93. (www)

  @article{ , abstract = {We utilize the cosmological volume simulation FIREbox to investigate how a galaxy's environment influences its size and dark matter content. Our study focuses on approximately 1200 galaxies (886 central and 332 satellite halos) in the low-mass regime, with stellar masses between 10 6 and 10 9 M ⊙ . We analyze the size–mass relation ( r 50 – M ⋆ ), the inner dark matter mass–stellar mass ( {M}_{{\rm{DM}}}^{50} – M ⋆ ) relation, and the halo mass–stellar mass ( M halo – M ⋆ ) relation. At fixed stellar mass, we find that galaxies experiencing stronger tidal influences, indicated by higher Perturbation Indices (PI > 1) are generally larger and have lower halo masses relative to their counterparts with lower Perturbation Indices (PI < 1). Applying a Random Forest regression model, we show that both the environment (PI) and halo mass ( M halo ) are significant predictors of a galaxy's relative size and dark matter content. Notably, because M halo is also strongly affected by the environment, our findings indicate that environmental conditions not only influence galactic sizes and relative inner dark matter content directly, but also indirectly, through their impact on halo mass. Our results highlight a critical interplay between environmental factors and halo mass in shaping galaxy properties, affirming the environment as a fundamental driver in galaxy formation and evolution.}, archive = {J_ApJ}, author = {Francisco J. Mercado and Jorge Moreno and Robert Feldmann and Marckie Zeender and José A. Benavides and Joanna M. Piotrowska and Courtney Klein and Coral Wheeler and Lina Necib and James S. Bullock and Philip F. Hopkins}, doi = {10.3847/1538-4357/adbf07}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {93}, shortjournal = {The Astrophys. J.}, title = {Effects of galactic environment on size and dark matter content in low-mass galaxies}, volume = {983}, year = {2025}, }
• (2025). The dwarf irregular galaxy NGC 6822. II. young, intermediate and old stellar populations: Comparison between theory and observations. ApJ, 983(2), 92. (www)

  @article{ , abstract = {This paper presents a quantitative analysis of the stellar content in the Local Group dwarf irregular galaxy NGC 6822 by comparing stellar evolution models and observations in color–magnitude diagrams (CMDs) and color–color diagrams (CC-Ds). Our analysis is based on optical ground-based g , r , i photometry, and deep archival Hubble Space Telescope photometry of two fields in the galactic disk. We compared young, intermediate-age, and old stellar populations with isochrones from the BaSTI-IAC library and found that NGC 6822 hosts a quite metal-rich ([Fe/H] = −0.7 to −0.4) young component with an age ranging from 20–100 Myr. The intermediate-age population experienced a modest chemical enrichment between 4 and 8 Gyr ago, while stars older than 11 Gyr have a low metal abundance ([Fe/H] ∼ −1.70). We also identified the asymptotic giant branch (AGB) clump population with a luminosity peak at i ∼ 23.35 mag. Our analysis of both the CMD and the optical–near-IR (NIR)–mid-IR (MIR) CC-Ds of AGB oxygen- and carbon-rich stars, using the PARSEC+COLIBRI isochrones with and without circumstellar dust, reveals that this stellar component exhibits a spread in age from 1–2 Gyr and in metallicity between [Fe/H] = −1.30 and −1.70. The stellar models we used reproduce very well the two distinct color sequences defined by AGB O- and C-rich stars in the various optical–NIR–MIR CC-Ds, suggesting that they are reliable diagnostics to identify and characterize intermediate-age stellar populations. However, we also find that evolutionary prescriptions in the optical i -( r − i ) CMDs predict, at fixed color, systematically lower luminosities than observed AGB stars.}, archive = {J_ApJ}, author = {Maria Tantalo and Giuseppe Bono and Maurizio Salaris and Adriano Pietrinferni and Matteo Monelli and Michele Fabrizio and Vittorio F. Braga and Annalisa Calamida and Massimo Dall’Ora and Valentina D’Orazi and Ivan Ferraro and Giuliana Fiorentino and Giacinto Iannicola and Massimo Marengo and Noriyuki Matsunaga and Joseph P. Mullen and Peter B. Stetson}, doi = {10.3847/1538-4357/adbf0e}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {92}, shortjournal = {The Astrophys. J.}, title = {The dwarf irregular galaxy NGC 6822. II. young, intermediate and old stellar populations: Comparison between theory and observations}, volume = {983}, year = {2025}, }
• (2025). Constraining reionization with lyα damping-wing absorption in galaxy spectra: A machine learning model based on reionization simulations. ApJ, 983(2), 91. (www)

  @article{ , abstract = {Recently, NIRSpec PRISM/CLEAR observations by JWST have begun providing rest-frame UV continuum measurements of galaxies at z ≳ 7, revealing signatures of Ly α damping-wing (DW) absorption by the intergalactic medium (IGM). We develop a methodology to constrain the global ionization fraction of the IGM ( Q HII ) using low-resolution spectra, employing the random forest classification (RFC) method. We construct mock spectra using the simulated galaxies and the IGM from the Cosmic Dawn II simulation and train RFC models to estimate Q HII at the redshift of the source and to detect the presence of a damped Ly α absorber. We find that individual galaxy spectra with spectral bins between 1220 and 1270 Å and with signal-to-noise ratios (SNR) >20 can place tight constraints on Q HII , provided the UV continuum is accurately modeled. This method is particularly effective for the early phase of reionization ( Q HII < 50%), when the IGM opacity is high in the DW. As a demonstration, we apply our model to existing NIRSpec PRISM/CLEAR spectra, placing upper bounds of Q HII = 59.6%, 5.6%, and 18.5% at z = 7.7, 9.4, and 10.6, respectively, with 68% confidence, though several modeling uncertainties remain to be discussed. These constraints favor late-starting reionization models, where ≳80% of the IGM is ionized after z = 8. We conclude that high-SNR observations of carefully selected targets around z ∼ 7–9 can effectively constrain reionization models.}, archive = {J_ApJ}, author = {Hyunbae Park and Intae Jung and Hidenobu Yajima and Jenny G. Sorce and Paul R. Shapiro and Kyungjin Ahn and Pierre Ocvirk and Romain Teyssier and Gustavo Yepes and Ilian T. Iliev and Joseph S. W. Lewis}, doi = {10.3847/1538-4357/adc001}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {91}, shortjournal = {The Astrophys. J.}, title = {Constraining reionization with lyα damping-wing absorption in galaxy spectra: A machine learning model based on reionization simulations}, volume = {983}, year = {2025}, }
• (2025). Effects of intrinsic active galactic nucleus variability on optical quasiperiodic oscillations related to subparsec binary black hole systems in broad-line active galactic nuclei. ApJ, 983(2), 90. (www)

  @article{ , abstract = {In this paper, an oversimplified model is proposed to test the effects of intrinsic active galactic nucleus (AGN) variability on expected optical quasiperiodic oscillations (QPOs) related to subparsec binary black hole systems (BBHs) in broad-line AGN. The commonly accepted continuous autoregressive process is applied to describe intrinsic AGN variability related to each BH accreting system in a subparsec BBH system. Considering obscurations related to orbital rotations with periodicity T p , artificial light curves including signals for optical QPOs can be built. Then, comparing the intrinsic periodicities T p with the measured robust periodicities T o through the artificial light curves, we find distributions of T p / T o have four significant peaks around 1, 2, 3, and 4, leading less than half of the artificial light curves to have consistency between T o and T p . Moreover, different collected model parameters have few effects on the distributions of T p / T o , indicating the effects of intrinsic AGN variability on optical QPOs are significantly strong and stable. Furthermore, after checking properties of optical QPOs in the light curves with different time steps, we find there are tiny effects of time steps on optical QPOs.}, archive = {J_ApJ}, author = {XueGuang Zhang}, doi = {10.3847/1538-4357/adc0a3}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {90}, shortjournal = {The Astrophys. J.}, title = {Effects of intrinsic active galactic nucleus variability on optical quasiperiodic oscillations related to subparsec binary black hole systems in broad-line active galactic nuclei}, volume = {983}, year = {2025}, }
• (2025). Gravitational instability in protoplanetary disk with cooling: 2D global analysis. ApJ, 983(2), 89. (www)

  @article{ , abstract = {Self-gravity is important in protoplanetary disks for planet formation through gravitational instability (GI). We study the cooling effect on GI in a thin two-dimensional protoplanetary disk. By solving the linear perturbation equations in global geometry, we obtain all the normal modes. Faster cooling leads to faster growth rate of GI with lower azimuthal wavenumber m . According to the spatial structure of normal modes at different mass-averaged Toomre number \overline{Q} and dimensionless cooling timescale β , we identify three modes: local, transitional, and global. The transitional modes are located in the outer disk, while the other two modes in the inner disk. At β ≈ 1 (the resonance of dynamical timescale and thermal timescale) the growth rate changes sharply and the transitional modes dominate. The disk α due to GI is much higher in the transitional modes than in the other two. Our results imply that the transitional modes at \overline{Q}\approx 1 and β ≈ 1 can plausibly interpret the substructures and planet/brown dwarf formation in the outer disk.}, archive = {J_ApJ}, author = {Zehao Su and Xing Wei}, doi = {10.3847/1538-4357/adc0ff}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {89}, shortjournal = {The Astrophys. J.}, title = {Gravitational instability in protoplanetary disk with cooling: 2D global analysis}, volume = {983}, year = {2025}, }
• (2025). Tight bound on the neutron star radius with quasiperiodic oscillations in short gamma-ray bursts. ApJ, 983(2), 88. (www)

  @article{ , abstract = {Quasiperiodic oscillations (QPOs) have been recently discovered in the short gamma-ray bursts (GRBs) 910711 and 931101B. Their frequencies are consistent with those of the quasiradial and quadrupolar oscillations of binary neutron star (BNS) merger remnants, as obtained in numerical relativity simulations. These simulations reveal quasi-universal relations between the remnant oscillation frequencies and the tidal coupling constant of the binaries. Under the assumption that the observed QPOs are due to these postmerger oscillations, we use the frequency–tide relations in a Bayesian framework to infer the source redshift, as well as the chirp mass and the binary tidal deformability of the BNS progenitors for GRBs 910711 and 931101B. We further use this inference to estimate bounds on the mass–radius relation for neutron stars. By combining the estimates from the two GRBs, we find a 68% credible range {R}_{1.4}=12.4{8}_{-0.40}^{+0.41} km for the radius of a neutron star with mass M = 1.4 M ⊙ , which is one of the tightest bounds to date.}, archive = {J_ApJ}, author = {Victor Guedes and David Radice and Cecilia Chirenti and Kent Yagi}, doi = {10.3847/1538-4357/adc101}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {88}, shortjournal = {The Astrophys. J.}, title = {Tight bound on the neutron star radius with quasiperiodic oscillations in short gamma-ray bursts}, volume = {983}, year = {2025}, }
• (2025). Revealing a main-sequence star that consumed a planet with JWST. ApJ, 983(2), 87. (www)

  @article{ , abstract = {The subluminous red nova (SLRN) Zwicky Transient Facility (ZTF) SLRN-2020 is the most compelling direct detection of a planet being consumed by its host star, a scenario known as a planetary engulfment event. We present JWST spectroscopy of ZTF SLRN-2020 taken +830 days after its optical emission peak using the NIRSpec fixed-slit 3–5 μ m high-resolution grating and the MIRI 5–12 μ m low-resolution spectrometer. NIRSpec reveals the 12 CO fundamental band ( ν = 1–0) in emission at ∼4.7 μ m, Brackett- α emission, and the potential detection of PH 3 in emission at ∼4.3 μ m. The JWST spectra are consistent with the claim that ZTF SLRN-2020 arose from a planetary engulfment event. We utilize DUSTY to model the late-time ∼1–12 μ m spectral energy distribution (SED) of ZTF SLRN-2020, where the best-fit parameters indicate the presence of warm, 72{0}_{-50}^{+80} K, circumstellar dust with a total dust mass of Log \left(\tfrac{{M}_{{\rm{d}}}}{{M}_{\odot }}\right)=-10.6{1}_{-0.16}^{+0.08} M ⊙ . We also fit a DUSTY model to archival photometry taken +320 days after the peak that suggested the presence of a cooler, {T}_{{\rm{d}}}=28{0}_{-20}^{+450} K, and more massive, Log \left(\tfrac{{M}_{{\rm{d}}}}{{M}_{\odot }}\right)=-5.8{9}_{-3.21}^{+0.29} , circumstellar dust component. Assuming the cool component originates from the ZTF SLRN-2020 ejecta, we interpret the warm component as fallback from the ejecta. From the late-time SED model, we measure a luminosity of {L}_{* }=0.2{9}_{-0.06}^{+0.03} L ⊙ for the remnant host star, which is consistent with a ∼0.7 M ⊙ K-type star that should not yet have evolved off the main sequence. If ZTF SLRN-2020 was not triggered by stellar evolution, we suggest that the planetary engulfment was due to orbital decay from tidal interactions between the planet and the host star.}, archive = {J_ApJ}, author = {Ryan M. Lau and Jacob E. Jencson and Colette Salyk and Kishalay De and Ori D. Fox and Matthew J. Hankins and Mansi M. Kasliwal and Charles D. Keyes and Morgan Macleod and Michael E. Ressler and Sam Rose}, doi = {10.3847/1538-4357/adb429}, journal = {The Astrophysical Journal}, month = {4}, number = {2}, pages = {87}, shortjournal = {The Astrophys. J.}, title = {Revealing a main-sequence star that consumed a planet with JWST}, volume = {983}, year = {2025}, }
• (2025). Discovery and extensive follow-up of SN 2024ggi, a nearby type IIP supernova in NGC 3621. ApJ, 983(1), 86. (www)

  @article{ , abstract = {We present the discovery and early observations of the nearby Type II supernova (SN) 2024ggi in NGC 3621 at 6.64 ± 0.3 Mpc. The SN was caught 5.{8}_{-2.9}^{+1.9} hr after its explosion by the ATLAS survey. Early-phase, high-cadence, and multiband photometric follow-up was performed by the Kilonova Finder (Kinder) project, collecting over 1000 photometric data points within 1 week. The combined o - and r -band light curves show a rapid rise of 3.3 mag in 13.7 hr, much faster than SN 2023ixf (another nearby and well-observed SN II). Between 13.8 and 18.8 hr after explosion, SN 2024ggi became bluer, with u − g color dropping from 0.53 to 0.15 mag. The rapid blueward evolution indicates a wind shock breakout (SBO) scenario. No hour-long brightening expected for the SBO from a bare stellar surface was detected during our observations. The classification spectrum, taken 17 hr after the SN explosion, shows flash features of high-ionization species such as Balmer lines, He i , C iii , and N iii . Detailed light-curve modeling provides critical insights into the circumstellar material (CSM). Our favored model has an explosion energy of 2 × 10 51 erg, a mass-loss rate of 10 −3 M ⊙ yr −1 (with an assumed 10 km s −1 wind), and a confined CSM radius of 6 × 10 14 cm. The corresponding CSM mass is 0.4 M ⊙ . Comparisons with SN 2023ixf highlight that SN 2024ggi has a less dense confined CSM, resulting in a faster rise and fainter UV flux. Citizen astronomer collaboration and extensive data are essential for SBO searches and detailed SN characterizations.}, archive = {J_ApJ}, author = {Ting-Wan Chen and Sheng Yang and Shubham Srivastav and Takashi J. Moriya and Stephen J. Smartt and Sofia Rest and Armin Rest and Hsing Wen Lin and Hao-Yu Miao and Yu-Chi Cheng and Amar Aryan and Chia-Yu Cheng and Morgan Fraser and Li-Ching Huang and Meng-Han Lee and Cheng-Han Lai and Yu-Hsuan Liu and Aiswarya Sankar.K and Ken W. Smith and Heloise F. Stevance and Ze-Ning Wang and Joseph P. Anderson and Charlotte R. Angus and Thomas de Boer and Kenneth Chambers and Hao-Yuan Duan and Nicolas Erasmus and Michael Fulton and Hua Gao and Joanna Herman and Wei-Jie Hou and Hsiang-Yao Hsiao and Mark E. Huber and Chien-Cheng Lin and Hung-Chin Lin and Eugene A. Magnier and Ka Kit Man and Thomas Moore and Chow-Choong Ngeow and Matt Nicholl and Po-Sheng Ou and Giuliano Pignata and Yu-Chien Shiau and Julian Silvester Sommer and John L. Tonry and Xiao-Feng Wang and Richard Wainscoat and David R. Young and You-Ting Yeh and Jujia Zhang}, doi = {10.3847/1538-4357/adb428}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {86}, shortjournal = {The Astrophys. J.}, title = {Discovery and extensive follow-up of SN 2024ggi, a nearby type IIP supernova in NGC 3621}, volume = {983}, year = {2025}, }
• (2025). AGILE observations of a sample of repeating fast radio burst sources. ApJ, 983(1), 85. (www)

  @article{ , abstract = {Fast radio bursts (FRBs) are millisecond-duration bursts originating from distant sources. They are classified into two categories: non-repeating FRBs, which manifest as singular events, and repeater FRBs (R-FRBs), which emit multiple bursts over time. In this work, we report a search for X- and γ -ray counterparts to a selected sample of R-FRBs using data from the AGILE satellite. The sample focused on sources with an excess dispersion measure (DM) below 300 pc cm −3 . The analysis focused on the bursts covered by AGILE Mini-Calorimeter (MCAL) high-resolution data. No astrophysical signals were identified, and we derived upper limits (ULs) on the flux above 400 keV for the associated sources, adopting a spectral magnetar model, one of the leading models for FRB emission. Moreover, for a single burst of FRB 20200120E we estimated the flux ULs from the SuperAGILE detector data in the 18–60 keV energy range. We also performed a check of the GRID coverage for each burst in the 0.03–10 GeV energy band on short timescales, from 10 to 10 3 s, and on longer ones including the complete ∼17 yr AGILE/GRID archive. We then considered the famous event FRB 200428 from the Galactic magnetar SGR 1935+2154 as a reference to extrapolate a possible X-ray emission in MCAL and SuperAGILE bands from the radio energies of R-FRBs using the E X / E radio of FRB 200428 as a fixed parameter. We compared these energies with historical magnetar X-ray bursts rescaled in the same bands. Our observations set useful constraints on the FRB magnetar model in particular, the MCAL ULs are currently the most stringent in the 0.4–30 MeV band.}, archive = {J_ApJ}, author = {Claudio Casentini and Francesco Verrecchia and Marco Tavani and Maura Pilia and Luigi Pacciani}, doi = {10.3847/1538-4357/adbe6f}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {85}, shortjournal = {The Astrophys. J.}, title = {AGILE observations of a sample of repeating fast radio burst sources}, volume = {983}, year = {2025}, }
• (2025). Clustering analysis of ca i 4227 line polarization using magnetohydrodynamic simulations of the solar atmosphere. ApJ, 983(1), 84. (www)

  @article{ , abstract = {The Ca i 4227 Å line is a strong resonance line formed in the solar chromosphere. At the limb, it produces the largest scattering polarization signal. So far, modeling the linear polarization in this line has been limited to the use of one-dimensional semiempirical models of the solar atmosphere. Using three-dimensional magnetohydrodynamical models of the solar atmosphere, in this paper, we perform 1.5D radiative transfer calculations to understand the formation of linear polarization profiles due to resonance scattering in this line at a near limb position. We focus on studying the sensitivity of the resonance scattering polarization to the temperature and the density structures in the atmosphere. We do not include the effects of magnetic and velocity fields in this study. We use clustering analysis to identify linear polarization profiles with similar shapes and group them accordingly for our study. We analyze the structure of the linear polarization profiles across 14 clusters, each representing different realizations of the solar atmosphere. Using source function ratio plots at various wing and core wavelength positions, we provide a qualitative explanation of linear polarization profiles in these clusters.}, archive = {J_ApJ}, author = {Harsh Mathur and L. S. Anusha and Devang Agnihotri}, doi = {10.3847/1538-4357/adbe76}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {84}, shortjournal = {The Astrophys. J.}, title = {Clustering analysis of ca i 4227 line polarization using magnetohydrodynamic simulations of the solar atmosphere}, volume = {983}, year = {2025}, }
• (2025). The distant milky way halo from the southern hemisphere: Characterization of the LMC-induced dynamical friction wake*. ApJ, 983(1), 83. (www)

  @article{ , abstract = {The infall of the Large Magellanic Cloud (LMC) into the Milky Way's halo impacts the distribution of stars and dark matter (DM) in our Galaxy. Mapping the observational consequences of this encounter can inform us about the properties of both galaxies, details of their interaction, and possibly distinguish between different DM models. N -body simulations predict a localized overdensity trailing the LMC's orbit both in baryonic and DM, known as the wake. We collected wide-field, deep near-infrared, and optical photometry using VIRCAM and DECam across four fields along the expected wake, covering the sky region expected to span most of its predicted density contrast. We identify over 400 stars comprising two different tracers, near main-sequence turnoff stars and red giants, which map the halo between 60 and 100 kpc, deriving stellar halo densities as a function of sky position and Galactocentric radius. We detect (1) a break in the halo radial density profile at 70 kpc not seen in northern halo studies and (2) a clear halo overdensity starting also at 70 kpc, with density contrast increasing steadily toward the expected current location of the wake. If this overdensity is the LMC wake, its peak density contrast is as pronounced as the most massive LMC model considered. Contamination from unidentified substructures may bias our wake detections, so wider-area surveys with similar depth are needed for confirmation.}, archive = {J_ApJ}, author = {Manuel Cavieres and Julio Chanamé and Camila Navarrete and Yasna Ordenes-Briceño and Nicolás Garavito-Camargo and Gurtina Besla and Maren Hempel and A. Katherina Vivas and Facundo Gómez}, doi = {10.3847/1538-4357/adbf08}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {83}, shortjournal = {The Astrophys. J.}, title = {The distant milky way halo from the southern hemisphere: Characterization of the LMC-induced dynamical friction wake*}, volume = {983}, year = {2025}, }
• (2025). Analysis of CME interactions in solar corona combining coronagraphic observations with wide-field imagers from solar orbiter and parker solar probe. ApJ, 983(1), 82. (www)

  @article{ , abstract = {Accurately determining the trajectory of coronal mass ejections (CMEs) is vital for space weather forecasting and assessing their potential impact on Earth. CMEs often deviate from a radial path, due to local pressure gradients or interactions with other CMEs. Combining coronagraphic and heliospheric observations offers deeper insights into these phenomena, enhancing future space weather prediction capabilities. On 2023 September 24, a sequence of four CMEs was observed by several spacecraft within 10 hr. This study provides a detailed analysis of these CMEs, with three-dimensional trajectories determined using a Graduated Cylindrical Shell forward-modeling technique. For the first time, this approach integrates quasi-simultaneous coronagraph data from STEREO-A and Solar and Heliospheric Observatory as well as heliospheric imaging from both Solar Orbiter and Parker Solar Probe. This multi-instrument, multi-viewpoint method allowed us to identify several indications of interaction between the second and third CMEs. This study aims to examine the consequences of interaction in low corona between two CMEs originating from closely spaced source regions on the propagation of both. In particular, the analysis revealed a southward deflection of approximately 15° in latitude for CME3 from its source region, as well as an acceleration of CME2. Following the acceleration, the two CMEs appear to propagate as a single entity at a uniform speed of approximately 750 km s −1 . Various interpretations are proposed to explain observations and indications of CME interactions.}, archive = {J_ApJ}, author = {Alessandro Liberatore and Paulett C. Liewer and Manuela Temmer and Greta M. Cappello and Yara De Leo and Paulo Penteado}, doi = {10.3847/1538-4357/adbffd}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {82}, shortjournal = {The Astrophys. J.}, title = {Analysis of CME interactions in solar corona combining coronagraphic observations with wide-field imagers from solar orbiter and parker solar probe}, volume = {983}, year = {2025}, }
• (2025). Discovery of radio recombination lines from proplyds in the orion nebula cluster. ApJ, 983(1), 81. (www)

  @article{ , abstract = {We present new Atacama Large Millimeter/submillimeter Array observations that, for the first time, detect hydrogen and helium radio recombination lines from a protoplanetary disk. We imaged the Orion Nebula Cluster at 3.1 mm with a spectral setup that covered the n = 42 → 41 transitions of hydrogen (H41 α ) and helium (He41 α ). The unprecedented sensitivity of these observations enables us to search for radio recombination lines toward the positions of ∼200 protoplanetary disks. We detect H41 α from 17 disks, all of which are HST-identified "proplyds." The detected H41 α emission is spatially coincident with the locations of proplyd ionization fronts, indicating that proplyd H41 α emission is produced by gas that has been photoevaporated off the disk and ionized by UV radiation from massive stars. We measure the fluxes and widths of the detected H41 α lines and find line fluxes of ∼30–800 mJy km s −1 and line widths of ∼30–90 km s −1 . The derived line widths indicate that the broadening of proplyd H41 α emission is dominated by outflowing gas motions associated with external photoevaporation. The derived line fluxes, when compared with measurements of 3.1 mm free–free flux, imply that the ionization fronts of H41 α -detected proplyds have electron temperatures of ∼6000–11,000 K and electron densities of ∼10 6 –10 7 cm −3 . Finally, we detect He41 α toward one H41 α -detected source and find evidence that this system is helium-rich. Our study demonstrates that radio recombination lines are readily detectable in ionized photoevaporating disks, providing a new way to measure disk properties in clustered star-forming regions.}, archive = {J_ApJ}, author = {Ryan D. Boyden and Kimberly L. Emig and Nicholas P. Ballering and Charles J. Law and Thomas J. Haworth and Jonathan C. Tan and L. Ilsedore Cleeves and Zhi-Yun Li}, doi = {10.3847/1538-4357/adbbcc}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {81}, shortjournal = {The Astrophys. J.}, title = {Discovery of radio recombination lines from proplyds in the orion nebula cluster}, volume = {983}, year = {2025}, }
• (2025). Simulating the photospheric to coronal plasma using magnetohydrodyanamic characteristics. II. reflections on non-reflecting boundary conditions. ApJ, 983(1), 80. (www)

  @article{ , abstract = {We present our implementation of non-reflecting boundary conditions in the magnetohydrodynamics (MHD) code LaRe3D. This implementation couples a characteristics-based boundary condition with a Lagrangian remap code, demonstrating the generality and flexibility of such non-reflecting boundary conditions for use with arbitrary grid-based MHD schemes. To test this implementation for perturbations on a background state, we present simulations of a hot sphere in an angled magnetic field. We then examine a series of simulations where we advect a spheromak through a non-reflecting boundary condition at four speeds related to the fast and slow magnetosonic speeds and the Alfvén speed. We compare the behavior of these simulations to ground truth simulations run from the same initial condition on an extended grid that keeps the spheromak in the simulation volume at all times. We find that the non-reflecting boundary condition can lead to severe, physical differences developing between a simulation using a non-reflecting boundary and a ground truth simulation using a larger simulation volume. We conclude by discussing the origins of these differences.}, archive = {J_ApJ}, author = {N. Dylan Kee and Lucas A. Tarr and Peter W. Schuck and Mark G. Linton and James E. Leake}, doi = {10.3847/1538-4357/adb132}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {80}, shortjournal = {The Astrophys. J.}, title = {Simulating the photospheric to coronal plasma using magnetohydrodyanamic characteristics. II. reflections on non-reflecting boundary conditions}, volume = {983}, year = {2025}, }
• (2025). A spectroscopically calibrated prescription for extracting polycyclic aromatic hydrocarbon flux from JWST MIRI imaging. ApJ, 983(1), 79. (www)

  @article{ , abstract = {We introduce a prescription for estimating the flux of the 7.7 μ m and 11.3 μ m polycyclic aromatic hydrocarbon (PAH) features from broadband JWST/MIRI images. Probing PAH flux with MIRI imaging data has advantages in field of view, spatial resolution, and sensitivity compared with MIRI spectral maps, but comparisons with spectra are needed to calibrate these flux estimations over a wide variety of environments. For 267 MIRI/MRS spectra from independent regions in the four luminous infrared galaxies (LIRGs) in the Great Observatories All-sky LIRG Survey Early Release Science program, we derive synthetic filter photometry and directly compare estimated PAH fluxes to those measured from detailed spectral fits. We find that for probing PAH 7.7 μ m, the best combination of filters is F560W, F770W, and either F1500W or F2100W, and the best for PAH 11.3 μ m is F560W, F1000W, F1130W, and F1500W. The prescription with these combinations yields predicted flux densities that typically agree with values from spectral decomposition within ∼7% and ∼5% for PAH 7.7 and 11.3 μ m, respectively.}, archive = {J_ApJ}, author = {Grant P. Donnelly and Thomas S.-Y. Lai and Lee Armus and Tanio Díaz-Santos and Kirsten L. Larson and Loreto Barcos-Muñoz and Marina Bianchin and Thomas Bohn and Torsten Böker and Victorine A. Buiten and Vassilis Charmandaris and Aaron S. Evans and Justin Howell and Hanae Inami and Darshan Kakkad and Laura Lenkić and Sean T. Linden and Cristina M. Lofaro and Matthew A. Malkan and Anne M. Medling and George C. Privon and Claudio Ricci and J. D. T. Smith and Yiqing Song and Sabrina Stierwalt and Paul P. van der Werf and Vivian U}, doi = {10.3847/1538-4357/adb97f}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {79}, shortjournal = {The Astrophys. J.}, title = {A spectroscopically calibrated prescription for extracting polycyclic aromatic hydrocarbon flux from JWST MIRI imaging}, volume = {983}, year = {2025}, }
• (2025). X-ray polarization of the high-synchrotron-peak BL lacertae object 1ES 1959+650 during intermediate and high X-ray flux states. ApJ, 983(1), 78. (www)

  @article{ , abstract = {We report the Imaging X-ray Polarimetry Explorer (IXPE) polarimetric and simultaneous multiwavelength observations of the high-energy-peaked BL Lacertae object (HBL) 1ES 1959+650, performed in 2022 October and 2023 August. In 2022 October, IXPE measured an average polarization degree Π X = 9.4% ± 1.6% and an electric-vector position angle ψ X = 53° ± 5°. The polarized X-ray emission can be decomposed into a constant component, plus a rotating component, with the rotation velocity ω EVPA = (−117 ± 12) deg day −1 . In 2023 August, during a period of pronounced activity of the source, IXPE measured an average Π X = 12.4% ± 0.7% and ψ X = 20° ± 2°, with evidence (∼0.4% chance probability) for a rapidly rotating component with ω EVPA = 1864 ± 34 deg day −1 . These findings suggest the presence of a helical magnetic field in the jet of 1ES 1959+650 or stochastic processes governing the field in turbulent plasma. Our multiwavelength campaigns from radio to X-ray reveal variability in both polarization and flux from optical to X-rays. We interpret the results in terms of a relatively slowly varying component dominating the radio and optical emission, while rapidly variable polarized components dominate the X-ray and provide minor contribution at optical wavelengths. The radio and optical data indicate that on parsec scales the magnetic field is primarily orthogonal to the jet direction. On the contrary, X-ray measurements show a magnetic field almost aligned with the parsec jet direction. Confronting with other IXPE observations, we guess that the magnetic field of HBLs on subparsec scale should be rather unstable, often changing its direction with respect to the Very Long Baseline Array jet.}, archive = {J_ApJ}, author = {Luigi Pacciani and Dawoon E. Kim and Riccardo Middei and Herman L. Marshall and Alan P. Marscher and Ioannis Liodakis and Iván Agudo and Svetlana G. Jorstad and Juri Poutanen and Manel Errando and Laura Di Gesu and Michela Negro and Fabrizio Tavecchio and Kinwah Wu and Chien-Ting Chen and Fabio Muleri and Lucio Angelo Antonelli and Immacolata Donnarumma and Steven R. Ehlert and Francesco Massaro and Stephen L. O’Dell and Matteo Perri and Simonetta Puccetti and Francisco José Aceituno and Giacomo Bonnoli and Víctor Casanova and Juan Escudero and Beatriz Agís-González and César Husillos and Daniel Morcuende and Jorge Otero-Santos and Alfredo Sota and Pouya M. Kouch and Elina Lindfors and George A. Borman and José L. Gómez and Evgenia N. Kopatskaya and Elena G. Larionova and Daria A. Morozova and Sergey S. Savchenko and Andrey A. Vasilyev and Alexey V. Zhovtan and Dmitry Blinov and Anastasia Gourni and Sebastian Kiehlmann and Angelos Kourtidis and Nikos Mandarakas and Efthymios Palaiologou and Nikolaos Triantafyllou and Anna Vervelaki and Ioannis Myserlis and Mark Gurwell and Garrett Keating and Ramprasad Rao and Emmanouil Angelakis and Alexander Kraus and Matteo Bachetti and Luca Baldini and Wayne H. Baumgartner and Ronaldo Bellazzini and Stefano Bianchi and Stephen D. Bongiorno and Raffaella Bonino and Alessandro Brez and Niccoló Bucciantini and Fiamma Capitanio and Simone Castellano and Elisabetta Cavazzuti and Stefano Ciprini and Enrico Costa and Alessandra De Rosa and Ettore Del Monte and Niccoló Di Lalla and Alessandro Di Marco and Victor Doroshenko and Michal Dovčiak and Teruaki Enoto and Yuri Evangelista and Sergio Fabiani and Riccardo Ferrazzoli and Javier A. Garcia and Shuichi Gunji and Kiyoshi Hayashida and Jeremy Heyl and Wataru Iwakiri and Philip Kaaret and Vladimir Karas and Fabian Kislat and Takao Kitaguchi and Jeffery J. Kolodziejczak and Henric Krawczynski and Fabio La Monaca and Luca Latronico and Simone Maldera and Alberto Manfreda and Frédéric Marin and Andrea Marinucci and Giorgio Matt and Ikuyuki Mitsuishi and Tsunefumi Mizuno and C.-Y. Ng and Nicola Omodei and Chiara Oppedisano and Alessandro Papitto and George G. Pavlov and Abel Lawrence Peirson and Melissa Pesce-Rollins and Pierre-Olivier Petrucci and Maura Pilia and Andrea Possenti and Brian D. Ramsey and John Rankin and Ajay Ratheesh and Oliver J. Roberts and Roger W. Romani and Carmelo Sgró and Patrick Slane and Paolo Soffitta and Gloria Spandre and Douglas A. Swartz and Toru Tamagawa and Roberto Taverna and Yuzuru Tawara and Allyn F. Tennant and Nicholas E. Thomas and Francesco Tombesi and Alessio Trois and Sergey S. Tsygankov and Roberto Turolla and Jacco Vink and Martin C. Weisskopf and Fei Xie and Silvia Zane}, doi = {10.3847/1538-4357/adbbe2}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {78}, shortjournal = {The Astrophys. J.}, title = {X-ray polarization of the high-synchrotron-peak BL lacertae object 1ES 1959+650 during intermediate and high X-ray flux states}, volume = {983}, year = {2025}, }
• (2025). Jet archaeology and forecasting: Image variability and magnetic field configuration. ApJ, 983(1), 77. (www)

  @article{ , abstract = {We investigate how magnetic field variations around accreting black holes (BHs) on event horizon scales affect the morphology of magnetically driven jets on larger scales. By performing radiative transfer calculations on general relativistic magnetohydrodynamics simulations, we find that temporal variation in the magnetic flux on the event horizon and the jet power are imprinted on the variability of jet width up to several hundred gravitational radii. When the magnetic flux around the BH drops and then rises, the jet initially narrows or becomes truncated, then widens, creating a thin-thick pattern that propagates down the jet. This suggests that extended jet observations can provide a history record of horizon-scale magnetic field dynamics, and conversely, upcoming changes in the jet image can be predicted from direct observation of the magnetized accreting plasma near the BH. Furthermore, the pattern of jet width variations shows acceleration up to the relativistic regime as it moves away from the BH, aligning with plasma bulk motion. We also find in time-averaged images that both the bulk plasma motion and magnetic field configuration in the jet-launching region, which are sensitive to BH spin, shape diverse features through relativistic beaming and aberration. Higher BH spins result in more poloidal bulk motion and toroidal magnetic fields, leading to more symmetric jet images and linear polarization patterns. These results suggest a new method for testing the magnetically arrested disk model and the Blandford–Znajek process, and for determining the BH spin through observations bridging horizon and jet-launching scales.}, archive = {J_ApJ}, author = {Yuh Tsunetoe and Ramesh Narayan and Angelo Ricarte}, doi = {10.3847/1538-4357/adbdcf}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {77}, shortjournal = {The Astrophys. J.}, title = {Jet archaeology and forecasting: Image variability and magnetic field configuration}, volume = {983}, year = {2025}, }
• (2025). Binary parameters for the recurrent nova t coronae borealis. ApJ, 983(1), 76. (www)

  @article{ , abstract = {T CrB is among the brightest novae. It is recurrent with outbursts happening approximately every 80 yr. The next outburst is imminent, expected in 2025. The T CrB binary consists of an M4 III red giant (RG) secondary and a white dwarf (WD) primary. A time series of spectra of the RG was obtained between 2022 and 2024. Radial velocities (RVs) from these data were combined with literature RVs and an updated orbit computed. The orbit is circular to a high precision and has a period of 227.5494 ± 0.0049 days for the circular solution. An eccentric solution yields an eccentricity of 0.0072 ± 0.0026. Rotational line broadening of the RG was also measured. Binary parameters are derived by maximum likelihood modeling of the available observational data. The WD, in accord with other estimates for recurrent novae, is massive. Assuming the Gaia distance, the WD mass is 1.37 ± 0.01 M ⊙ with the M giant secondary mass 0.6{9}_{-0.01}^{+0.02}\,{M}_{\odot } . We discuss the evolution of this system and both paths to and limitations on further refining the values of the system parameters.}, archive = {J_ApJ}, author = {Kenneth H. Hinkle and Pranav Nagarajan and Francis C. Fekel and Joanna Mikołajewska and Oscar Straniero and Matthew W. Muterspaugh}, doi = {10.3847/1538-4357/adbe63}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {76}, shortjournal = {The Astrophys. J.}, title = {Binary parameters for the recurrent nova t coronae borealis}, volume = {983}, year = {2025}, }
• (2025). Investigating the bouncing barrier with collision simulations of compressed dust aggregates. ApJ, 983(1), 75. (www)

  @article{ , abstract = {The collision outcomes of dust aggregates in protoplanetary disks dictate how planetesimals form. Experimental and numerical studies have suggested that bouncing collisions occurring at low impact velocities may limit aggregate growth in the disks, but the conditions under which bouncing occurs have yet to be fully understood. In this study, we perform a suite of collision simulations of moderately compact dust aggregates with various impact velocities, aggregate radii, and filling factors ranging between 0.4 and 0.5. Unlike previous simulations, we generate compact aggregates by compressing more porous ones, mimicking the natural processes through which compact aggregates form. We find that the compressed aggregates bounce above a threshold mass, which decreases with impact velocity. The threshold mass scales with impact velocity as the –4/3 power, consistent with the findings of previous experiments. We also find that the threshold aggregate mass for bouncing depends strongly on filling factor, likely reflecting the strong filling-factor dependence of the compressive strength of compressed aggregates. Our energy analysis reveals that nearly 90% of the initial impact energy is dissipated during the initial compression phase, and over 70% of the remaining energy is dissipated during the subsequent stretching phase, regardless of whether the collision results in sticking or bouncing. Our results indicate that dust aggregates with a filling factor of 0.4 cease to grow beyond 100 μ m as a result of the bouncing barrier.}, archive = {J_ApJ}, author = {Haruto Oshiro and Misako Tatsuuma and Satoshi Okuzumi and Hidekazu Tanaka}, doi = {10.3847/1538-4357/adbf04}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {75}, shortjournal = {The Astrophys. J.}, title = {Investigating the bouncing barrier with collision simulations of compressed dust aggregates}, volume = {983}, year = {2025}, }
• (2025). A spiral structure in the inner oort cloud. ApJ, 983(1), 74. (www)

  @article{ , abstract = {As the Galactic tide acts to decouple bodies from the scattered disk it creates a spiral structure in physical space that is roughly 15,000 au in length. The spiral is long-lived and persists in the inner Oort cloud to the present time. Here we discuss dynamics underlying the Oort spiral and (feeble) prospects for its observational detection.}, archive = {J_ApJ}, author = {David Nesvorný and Luke Dones and David Vokrouhlický and Hal F. Levison and Cristian Beaugé and Jacqueline Faherty and Carter Emmart and Jon P. Parker}, doi = {10.3847/1538-4357/adbf9b}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {74}, shortjournal = {The Astrophys. J.}, title = {A spiral structure in the inner oort cloud}, volume = {983}, year = {2025}, }
• (2025). Constraints on the X-ray and very-high-energy gamma-ray flux from supernova remnant w44. ApJ, 983(1), 73. (www)

  @article{ , abstract = {Observations of GeV gamma-ray emission from the well-studied mixed-morphology supernova remnant (SNR) W44 by Fermi-Large Area Telescope and AGILE imply that it is a site of significant cosmic-ray acceleration. The spectral energy distribution (SED) derived from the GeV data suggests that the gamma-ray emission likely originates from the decay of neutral pions generated by cosmic-ray interactions. It is essential to measure the SED of W44 in the X-ray and very-high-energy (VHE) gamma-ray bands to verify the hadronic origin of the emission and to gauge the potential contributions from leptonic emission. We report an upper limit of the nonthermal X-ray flux from W44 of 5 × 10 −13 erg cm −2 s −1 in the 0.5–8.0 keV band based on  ∼300 ks of XMM-Newton observations. The X-ray upper limit is consistent with previously estimated hadronic models, but in tension with the leptonic models. We estimate the VHE flux upper limit of  ∼1.2 × 10 −12 erg s −1 cm −2 in the 0.5–5.0 TeV range from W44 using data from the Very Energetic Radiation Imaging Telescope Array System. Our nondetection of W44 at VHE wavelengths is in agreement with observations from other imaging atmospheric Cherenkov telescopes and is perhaps consistent with the evolutionary stage of the SNR.}, archive = {J_ApJ}, author = {A. Archer and P. Bangale and J. T. Bartkoske and W. Benbow and J. H. Buckley and Y. Chen and J. L. Christiansen and A. J. Chromey and A. Duerr and M. Errando and M. Escobar Godoy and S. Feldman and Q. Feng and J. Foote and L. Fortson and A. Furniss and W. Hanlon and O. Hervet and C. E. Hinrichs and J. Holder and T. B. Humensky and W. Jin and M. N. Johnson and P. Kaaret and M. Kertzman and M. Kherlakian and D. Kieda and T. K. Kleiner and N. Korzoun and S. Kumar and S. Kundu and M. J. Lang and G. Maier and M. Lundy and M. J. Millard and C. L. Mooney and P. Moriarty and R. Mukherjee and W. Ning and R. A. Ong and M. Pohl and E. Pueschel and J. Quinn and P. L. Rabinowitz and K. Ragan and P. T. Reynolds and D. Ribeiro and E. Roache and L. Saha and M. Santander and G. H. Sembroski and R. Shang and D. Tak and A. K. Talluri and J. V. Tucci and D. A. Williams and S. L. Wong and J. Woo}, doi = {10.3847/1538-4357/adc07d}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {73}, shortjournal = {The Astrophys. J.}, title = {Constraints on the X-ray and very-high-energy gamma-ray flux from supernova remnant w44}, volume = {983}, year = {2025}, }
• (2025). Using lyα absorption to measure the intensity and variability of z ∼ 2.4 ultraviolet background light. ApJ, 983(1), 72. (www)

  @article{ , abstract = {We present measurements of z ∼ 2.4 ultraviolet (UV) background light using Ly α absorption from galaxies at z ∼ 2–3 in the Hobby–Eberly Telescope Dark Energy Experiment (HETDEX) database. Thanks to the wide area of this survey, we also measure the variability of this light across the sky. The data suggest an asymmetric geometry where integrated UV light from background galaxies is absorbed by H i within the halo of a foreground galaxy, in a configuration similar to damped Ly α systems. Using stacking analyses of over 400,000 HETDEX LAE spectra, we argue that this background absorption is detectable in our data. We also argue that the absorption signal becomes negative due to HETDEX's sky-subtraction procedure. The amount that the absorption is oversubtracted is representative of the z ∼ 2.4 UV contribution to the overall extragalactic background light (EBL) at Ly α . Using this method, we determine an average intensity (in νJ ν units) of 12.9 ± 3.7 nW m −2 sr −1 at a median observed wavelength of 4134 Å, or a rest-frame UV background intensity of 508 ± 145 nW m −2 sr −1 at z ∼ 2.4. We find that this flux varies significantly depending on the density of galaxies in the field of observation. Our estimates are consistent with direct measurements of the overall EBL.}, archive = {J_ApJ}, author = {Laurel H. Weiss and Karl Gebhardt and Dustin Davis and Erin Mentuch Cooper and Maja Lujan Niemeyer and Mahdi Qezlou and Mahan Mirza Khanlari and Robin Ciardullo and Daniel Farrow and Eric Gawiser and Simon Gazagnes and Caryl Gronwall and Gary J. Hill and Donald P. Schneider}, doi = {10.3847/1538-4357/adc0f9}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {72}, shortjournal = {The Astrophys. J.}, title = {Using lyα absorption to measure the intensity and variability of z ∼ 2.4 ultraviolet background light}, volume = {983}, year = {2025}, }
• (2025). Modeling the solar transition region: Effects of spatial resolution on the atmospheric structure, emission and non-equilibrium ionization. ApJ, 983(1), 71. (www)

  @article{ , abstract = {The solar transition region (TR) is a narrow interface between the chromosphere and corona, where emitted radiation contains critical information pertinent to coronal heating processes. We conducted two-dimensional radiation magnetohydrodynamics simulations using adaptive mesh refinement to spatially resolve the fine structure of the TR while simultaneously capturing the larger-scale dynamics originating from surface convection. The time evolution of ionization fractions for oxygen ions is computed alongside the simulations. A minimum grid size of 1.25 km is achieved in the TR, enabling adequate resolution of the upper TR (log 10 T ≳ 5), although the lower TR (log 10 T ≲ 5) remains under-resolved. Doppler shifts and nonthermal widths synthesized from TR lines exhibit convergence with grid sizes as coarse as 40 km, though some discrepancies persist between our results and observed TR line properties. A notable enhancement in emission from O vi lines, converging at a grid size of 2.5 km, shows an intensity 1.2 times that expected under ionization equilibrium, attributable to shock interactions with the TR. While model refinements are still required, our ability to resolve the TR offers critical insights into TR line characteristics arising from non-equilibrium ionization states, advancing our understanding of the coronal heating problem.}, archive = {J_ApJ}, author = {Takuma Matsumoto}, doi = {10.3847/1538-4357/adac5f}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {71}, shortjournal = {The Astrophys. J.}, title = {Modeling the solar transition region: Effects of spatial resolution on the atmospheric structure, emission and non-equilibrium ionization}, volume = {983}, year = {2025}, }
• (2025). HIP 8522: A puzzling young solar twin with the lowest detected lithium abundance*. ApJ, 983(1), 70. (www)

  @article{ , abstract = {We present HIP 8522, a young solar twin with the lowest detected lithium abundance, potentially a field blue straggler or the result of episodic early accretion. Its stellar parameters ( T eff = 5729 ± 7 K, \mathrm{log}\,g = 4.532 ± 0.016 dex, [Fe/H] = 0.005 ± 0.010 dex, and v t = 1.08 ± 0.02 km s −1 ) and chemical composition were determined via spectroscopic equilibrium using high-resolution spectra ( R = 60,000–165,000). The age of HIP 8522 was estimated to have an upper limit of <1 Gyr through isochrone fitting and was further confirmed using chemical clocks. Spectral synthesis of the lithium line at ∼6707.8 Å yielded an upper lithium abundance limit of A (Li) < 0.8 dex. This value is unusually low for solar twins of similar age, which typically have A (Li) values ranging from 2.0 to 3.3 dex, suggesting that ∼2 dex of lithium is missing. We investigate various scenarios, such as planet engulfment, substellar mergers, and extra mixing. However, two distinct hypotheses provide plausible explanations for the significant depletion of lithium: one suggests that HIP 8522 is a field blue straggler formed by the merger of a close binary, while the other proposes that HIP 8522 experienced early episodic accretion. The young solar twin HIP 8522 presents an exceptional opportunity to rigorously test stellar evolution models and gain crucial insights into the internal mixing mechanisms responsible for the significant destruction of lithium.}, archive = {J_ApJ}, author = {Jhon Yana Galarza and Diego Lorenzo-Oliveira and Thiago Ferreira and Henrique Reggiani and Aida Behmard and Joshua D. Simon and Eder Martioli and Ricardo López-Valdivia and Leandro de Almeida and Emiliano Jofré and Kareem El-Badry}, doi = {10.3847/1538-4357/adb57b}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {70}, shortjournal = {The Astrophys. J.}, title = {HIP 8522: A puzzling young solar twin with the lowest detected lithium abundance*}, volume = {983}, year = {2025}, }
• (2025). A 100 mpc2 structure traced by hyperluminous galaxies around a massive z = 2.85 protocluster. ApJ, 983(1), 69. (www)

  @article{ , abstract = {We present wide-field mapping at 850 μ m and 450 μ m of the z = 2.85 protocluster in the HS 1549+19 field using the Submillimetre Common-User Bolometer Array 2. Spectroscopic follow-up of 18 bright sources selected at 850 μ m, using the Northern Extended Millimeter Array and Atacama Large Millimeter/submillimeter Array, confirms that the majority lie near z ≃ 2.85 and are likely members of the structure. Interpreting the spectroscopic redshifts as distance measurements, we find that the submillimeter galaxies (SMGs) span 123 pMpc 2 in the plane of the sky and demarcate a 3600 pMpc 3 "pancake"-shaped structure in three dimensions. We find that the high star formation rates of these SMGs result in a total star formation rate of 20,000 M ⊙ yr −1 from just the brightest galaxies in the protocluster. These rapidly star-forming SMGs can be interpreted as massive galaxies growing rapidly at large clustercentric distances before collapsing into a virialized structure. We find that the SMGs trace the Ly α surface density profile. Comparison with simulations suggests that HS 1549+19 could be building a structure comparable to the most massive clusters in the present-day Universe.}, archive = {J_ApJ}, author = {George C.P. Wang and Scott C. Chapman and Nikolaus Sulzenauer and Frank Bertoldi and Christopher C. Hayward and Ryley Hill and Satoshi Kikuta and Yuichi Matsuda and Douglas Rennehan and Douglas Scott and Ian Smail and Charles C. Steidel}, doi = {10.3847/1538-4357/adb834}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {69}, shortjournal = {The Astrophys. J.}, title = {A 100 mpc2 structure traced by hyperluminous galaxies around a massive z = 2.85 protocluster}, volume = {983}, year = {2025}, }
• (2025). StreamSculptor: Hamiltonian perturbation theory for stellar streams in flexible potentials with differentiable simulations. ApJ, 983(1), 68. (www)

  @article{ , abstract = {Stellar streams are one of the most promising tracers of low-mass dark-matter subhalos. Existing frameworks for modeling stream perturbations rely on restrictive assumptions for the Milky Way potential (e.g., static, axisymmetric) or are computationally inefficient in generating many realizations of subhalo impacts. We present StreamSculptor , a GPU accelerated code that combines differentiable simulations and Hamiltonian perturbation theory to model the leading-order effect of dark-matter subhalos on stellar streams. Our model works in two stages: First, a base stream is generated in a Milky Way potential, including the effects of nonlinear time-dependent sources like the rotating Galactic bar and a massive satellite galaxy. Then, linear perturbation theory is applied to the base stream, allowing us to rapidly superimpose the effects of different subhalo impacts without having to carry out additional simulations. Subhalo masses and scale-radii can be rescaled as a postprocessing step. We demonstrate how this framework can be used to model subhalo impacts on stellar streams under realistic Milky Way conditions, specifically for an inner Galaxy stream like Palomar 5 and an outer Galaxy stream like Orphan–Chenab. We find that simultaneously modeling subhalo impacts and other time-dependent components of the Galactic gravitational potential is crucial for an unbiased inference of dark-matter substructure.}, archive = {J_ApJ}, author = {Jacob Nibauer and Ana Bonaca and David N. Spergel and Adrian M. Price-Whelan and Jenny E. Greene and Nathaniel Starkman and Kathryn V. Johnston}, doi = {10.3847/1538-4357/adb8e8}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {68}, shortjournal = {The Astrophys. J.}, title = {StreamSculptor: Hamiltonian perturbation theory for stellar streams in flexible potentials with differentiable simulations}, volume = {983}, year = {2025}, }
• (2025). Solar energetic particle events with extremely high 3He content observed by solar orbiter. ApJ, 983(1), 67. (www)

  @article{ , abstract = {We performed a survey of 3 He-rich events using observations from the Suprathermal Ion Spectrograph on the Solar Orbiter mission from 2020 to 2024. We identified 57 3 He-rich events, each showing clear 3 He enhancements above the background and 3 He/ 4 He abundance ratios greater than 1 in at least one energy channel in the range from 193.2 keV nucleon −1 to 8.74 MeV nucleon −1 . The analysis of the events' abundance ratios shows characteristics of impulsive solar energetic particle events with 3 He/ 4 He ∼ 3.1 and Fe/O ∼ 1.3. We observe an energy dependence in the 3 He/ 4 He ratio, which increases with energy, while the Fe/O ratios are almost constant with energy. We also found that six events in our list have extremely high 3 He content (e.g., 3 He/C–Fe ratios in the range 25–62). These events show curved 3 He and heavy nuclei spectra that roll over at higher energies and flatten toward low energy. Their spectral forms can be reasonably fit with simple exponentials with a 3 He rollover energy in the range of a few hundred keV per nucleon and a C–Fe rollover energy ∼2–3 times lower. The differences in spectral rollover energy lead to a strong energy dependence of the ratio 3 He/C–Fe, rising sharply with energy. We conclude that the features of these events with extremely high 3 He content have a reasonable likelihood of depicting the initial acceleration process, which is driven by magnetic reconnection in flaring loops near the solar surface.}, archive = {J_ApJ}, author = {A. Kouloumvakos and G. M. Mason and G. C. Ho and R. C. Allen and J. Rodriguez-Pacheco and R. F. Wimmer-Schweingruber}, doi = {10.3847/1538-4357/adbae7}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {67}, shortjournal = {The Astrophys. J.}, title = {Solar energetic particle events with extremely high 3He content observed by solar orbiter}, volume = {983}, year = {2025}, }
• (2025). Surveying the giant h ii regions of the milky way with SOFIA. VII. galactic center regions sgr b1, sgr b2, and sgr c. ApJ, 983(1), 66. (www)

  @article{ , abstract = {This study examines the mid-infrared properties of Giant H ii (GH ii ) regions in the Milky Way's Central Molecular Zone (CMZ)—Sgr B1, Sgr B2, and Sgr C—using SOFIA-FORCAST imaging at 25 and 37 μ m. It compares these mid-infrared data with previous multiwavelength observations to explore their present star formation activity and global properties. The study identifies 77 massive young stellar object (MYSO) candidates in and around the three regions. Sgr B2 appears to host the youngest MYSOs and have much higher extinction than the other regions, containing several radio sources not detected in the mid-infrared even at 37 μ m. Meanwhile, cm radio continuum regions of Sgr B1 shows remarkable correspondence to its mid-infrared emission. Sgr C has fewer confirmed MYSOs, and it seems to have a higher fraction of low-mass young stellar objects and contamination from more evolved interloper/foreground stars. Derived MYSO densities are consistent with GH ii regions elsewhere in the Galactic plane, though the CMZ GH ii regions appear to have less prolific present star formation overall. Unlike Sgr B2, the cm continuum emission in Sgr B1 and Sgr C GH ii regions appears to be absent cold dust and molecular gas, suggesting environmental differences, possibly driven by turbulence and rapid dynamical changes near the Galactic center. Furthermore, unlike typical GH ii regions, Sgr B1 and Sgr C are significantly ionized by evolved interloper stars, which likely did not form within these regions. In these ways, Sgr B1 and Sgr C deviate from classical GH ii region behavior, thus potentially representing a new category of GH ii region or challenging their classification as GH ii regions.}, archive = {J_ApJ}, author = {James M. De Buizer and Wanggi Lim and James T. Radomski and Nicole Karnath}, doi = {10.3847/1538-4357/adbbd9}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {66}, shortjournal = {The Astrophys. J.}, title = {Surveying the giant h ii regions of the milky way with SOFIA. VII. galactic center regions sgr b1, sgr b2, and sgr c}, volume = {983}, year = {2025}, }
• (2025). Jormungandr: A large substructure circling the milky way identified from gaia DR3 data. ApJ, 983(1), 65. (www)

  @article{ , abstract = {We report the discovery of a large substructure in the Milky Way passing through the solar neighborhood, detected in actions \left({J}_{\phi },{J}_{{\rm{R}}}\right) calculated from Gaia DR3 data. We perform extensive tests to evaluate the selection effects present in the sample and conclude that they cannot produce an artifact with the same characteristics. This substructure, which we call Jormungandr, is orbiting the Milky Way with high L Z , higher eccentricity (median ∼0.50) and larger rotation velocity V ϕ compared to disk stars. It leaves obvious patterns in the integrals of motion and kinematics. The chemical abundances from the Apache Point Observatory Galactic Evolution Experiment DR17 for members of Jormungandr resemble those of the Galactic disk high- α sequence. It shows a significant spread in metallicity, as well as age, according to its color–magnitude diagram. Understanding its formation and nature requires further analysis and simulations.}, archive = {J_ApJ}, author = {Xianhao Ye and Gang Zhao and Carlos Allende Prieto and Jingkun Zhao and Yong Yang and Wenbo Wu}, doi = {10.3847/1538-4357/adbc5f}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {65}, shortjournal = {The Astrophys. J.}, title = {Jormungandr: A large substructure circling the milky way identified from gaia DR3 data}, volume = {983}, year = {2025}, }
• (2025). Polycyclic aromatic hydrocarbon and CO(2–1) emission at 50–150 pc scales in 70 nearby galaxies. ApJ, 983(1), 64. (www)

  @article{ , abstract = {Combining Atacama Large Millimeter/submillimeter Array CO(2–1) mapping and JWST near- and mid-infrared imaging, we characterize the relationship between CO(2–1) and polycyclic aromatic hydrocarbon (PAH) emission at ≈100 pc resolution in 70 nearby star-forming galaxies. Leveraging a new Cycle 2 JWST Treasury program targeting nearby galaxies, we expand the sample size by more than an order of magnitude compared to previous ≈100 pc resolution CO–PAH comparisons. In regions of galaxies where most of the gas is likely to be molecular, we find strong correlations between CO(2–1) and 3.3 μ m, 7.7 μ m, and 11.3 μ m PAH emission, estimated from JWST's F335M, F770W, and F1130W filters. We derive power-law relations between CO(2–1) and PAH emission, with indices in the range 0.8–1.3, implying relatively weak variations in the observed CO-to-PAH ratios across our sample. We find that CO-to-PAH ratios and scaling relationships near H ii regions are similar to those in diffuse sight lines. The main difference between the two types of regions is that sight lines near H ii regions show higher intensities in all tracers. Galaxy centers show higher overall intensities and enhanced CO-to-PAH ratios compared to galaxy disks. Individual galaxies show 0.19 dex scatter in the normalization of CO at fixed I PAH , and this normalization anticorrelates with specific star formation rate and correlates with stellar mass. We provide a prescription that accounts for galaxy-to-galaxy variations, representing our best current empirical predictor to estimate CO(2–1) intensity from PAH emission, allowing one to take advantage of JWST's excellent sensitivity and resolution to trace cold gas.}, archive = {J_ApJ}, author = {Ryan Chown and Adam K. Leroy and Karin Sandstrom and Jérémy Chastenet and Jessica Sutter and Eric W. Koch and Hannah B. Koziol and Lukas Neumann and Jiayi Sun and Thomas G. Williams and Dalya Baron and Gagandeep S. Anand and Ashley. T. Barnes and Zein Bazzi and Francesco Belfiore and Frank Bigiel and Alberto Bolatto and Médéric Boquien and Yixian Cao and Mélanie Chevance and Dario Colombo and Daniel A. Dale and Jakob den Brok and Oleg V. Egorov and Cosima Eibensteiner and Eric Emsellem and Hamid Hassani and Jonathan D. Henshaw and Hao He and Jaeyeon Kim and Ralf S. Klessen and Kathryn Kreckel and Kirsten L. Larson and Janice C. Lee and Sharon E. Meidt and Eric J. Murphy and Elias K. Oakes and Eve C. Ostriker and Hsi-An Pan and Debosmita Pathak and Erik Rosolowsky and Sumit K. Sarbadhicary and Eva Schinnerer and Yu-Hsuan Teng and David A. Thilker and Tony D. Weinbeck and Elizabeth J. Watkins}, doi = {10.3847/1538-4357/adbd40}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {64}, shortjournal = {The Astrophys. J.}, title = {Polycyclic aromatic hydrocarbon and CO(2–1) emission at 50–150 pc scales in 70 nearby galaxies}, volume = {983}, year = {2025}, }
• (2025). A linear decomposition method to analyze and study pulsar mode changes. ApJ, 983(1), 63. (www)

  @article{ , abstract = {In this paper, we present the linear decomposition method (LDM), which we developed to detect and analyze pulsar profile variations and mode-changing behavior. We developed LDM utilizing the likelihood function approach assuming the Gaussian noise. The LDM projects pulse profiles onto significance-ordered orthonormal vector bases. We show that the method is similar to the principal component analysis, but the LDM can handle more general situations. We use a simulated data set and data from the Kunming 40 m radio telescope to demonstrate the application of the LDM. We found that the LDM successfully identified mode changes for well-known mode-changing PSR B0329+54 and found a continuous pulse profile evolution for PSR B0355+54. We also show that the LDM can be used to improve the timing precision for mode-changing PSR B0329+54.}, archive = {J_ApJ}, author = {Longfei Hao and Zhixuan Li and Faxin Shen and Yonghua Xu and Yuxiang Huang and Kejia Lee and Qingzheng Yu and Hongguang Wang}, doi = {10.3847/1538-4357/adbdb8}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {63}, shortjournal = {The Astrophys. J.}, title = {A linear decomposition method to analyze and study pulsar mode changes}, volume = {983}, year = {2025}, }
• (2025). The anomalous acceleration of PSR j2043+1711: Long-period orbital companion or stellar flyby?. ApJ, 983(1), 62. (www)

  @article{ , abstract = {Based on the rate of change of its orbital period, PSR J2043+1711 has a substantial peculiar acceleration of 3.5 ± 0.8 mm s –1 yr –1 , which deviates from the acceleration predicted by equilibrium Milky Way (MW) models at a 4 σ level. The magnitude of the peculiar acceleration is too large to be explained by disequilibrium effects of the MW interacting with orbiting dwarf galaxies (∼1 mm s –1 yr –1 ), and too small to be caused by period variations due to the pulsar being a redback. We identify and examine two plausible causes for the anomalous acceleration: a stellar flyby, and a long-period orbital companion. We identify a main-sequence star in Gaia DR3 and Pan-STARRS DR2 with the correct mass, distance, and on-sky position to potentially explain the observed peculiar acceleration. However, the star and the pulsar system have substantially different proper motions, indicating that they are not gravitationally bound. However, it is possible that this is an unrelated star that just happens to be located near J2043+1711 along our line of sight (chance probability of 1.6%). Therefore, we also constrain possible orbital parameters for a circumbinary companion in a hierarchical triple system with J2043+1711; the changes in the spindown rate of the pulsar are consistent with an outer object that has an orbital period of 60 kyr, a companion mass of 0.3 M ⊙ (indicative of a white dwarf or low-mass star), and a semimajor axis of 1900 au. Continued timing and/or future faint optical observations of J2043+1711 may eventually allow us to differentiate between these scenarios.}, archive = {J_ApJ}, author = {Thomas Donlon and Sukanya Chakrabarti and Michael T. Lam and Daniel Huber and Daniel Hey and Enrico Ramirez-Ruiz and Benjamin Shappee and David L. Kaplan and Gabriella Agazie and Akash Anumarlapudi and Anne M. Archibald and Zaven Arzoumanian and Paul T. Baker and Paul R. Brook and H. Thankful Cromartie and Kathryn Crowter and Megan E. DeCesar and Paul B. Demorest and Timothy Dolch and Elizabeth C. Ferrara and William Fiore and Emmanuel Fonseca and Gabriel E. Freedman and Nate Garver-Daniels and Peter A. Gentile and Joseph Glaser and Deborah C. Good and Jeffrey S. Hazboun and Mark Huber and Ross J. Jennings and Megan L. Jones and Matthew Kerr and Duncan R. Lorimer and Jing Luo and Ryan S. Lynch and Alexander McEwen and Maura A. McLaughlin and Natasha McMann and Bradley W. Meyers and Cherry Ng and David J. Nice and Timothy T. Pennucci and Benetge B. P. Perera and Nihan S. Pol and Henri A. Radovan and Scott M. Ransom and Paul S. Ray and Ann Schmiedekamp and Carl Schmiedekamp and Brent J. Shapiro-Albert and Ingrid H. Stairs and Kevin Stovall and Abhimanyu Susobhanan and Joseph K. Swiggum and Michael A. Tucker and Haley M. Wahl}, doi = {10.3847/1538-4357/adbf90}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {62}, shortjournal = {The Astrophys. J.}, title = {The anomalous acceleration of PSR j2043+1711: Long-period orbital companion or stellar flyby?}, volume = {983}, year = {2025}, }
• (2025). Connection between nonaxisymmetric structures and neutral gas distribution in disk galaxies. ApJ, 983(1), 61. (www)

  @article{ , abstract = {Nonaxisymmetric structures, such as bars and spiral arms, are known to concentrate molecular gas and star formation in galaxy centers, actively building up the pseudobulges. However, the direct link between the neutral (i.e., molecular and atomic) gas distribution and the exerted torque forces over a broader radial range of galactic disks still remains to be explored. In the present work, we investigate this link by carefully evaluating the torque force field using the 3.6 μ m images for 17 The H i Nearby Galaxy Survey galaxies, and measuring neutral gas distribution on resolved atomic and molecular line maps. We find that galaxies with stronger torque forces show a more concentrated neutral gas distribution over the disk scale, defined as half the isophotal radius at 25.5\,\mathrm{mag}\,{\mathrm{arcsec}}^{-2} . The correlation holds regardless of whether the neutral gas fraction or the effective stellar mass surface density is controlled for. In addition, kiloparsec-scale neutral gas overdensities tend to be located close to the local maxima of torque forces. Most of these correlations involving the torque forces are comparatively stronger than those using the traditional Fourier amplitudes to quantify the nonaxisymmetric structures. These results are consistent with the scenario that nonaxisymmetric structures exert torque forces and trigger dissipative processes to transport gas inward, not only to build the pseudobulges but also to fuel the inner disk growth. In this regard, nonaxisymmetric structures inducing stronger torque forces appear to be more efficient in these processes.}, archive = {J_ApJ}, author = {Ze-Zhong Liang and Jing Wang and Hua Gao and Luis C. Ho and E. Athanassoula}, doi = {10.3847/1538-4357/ad87f1}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {61}, shortjournal = {The Astrophys. J.}, title = {Connection between nonaxisymmetric structures and neutral gas distribution in disk galaxies}, volume = {983}, year = {2025}, }
• (2025). The host galaxy (If any) of the little red dots. ApJ, 983(1), 60. (www)

  @article{ , abstract = {We investigate the host galaxy properties of eight little red dots (LRDs) selected from the JWST UNCOVER survey, applying a new technique ( GalfitS ) to simultaneously fit the morphology and spectral energy distribution using multiband NIRCam images covering ∼1–4 μ m. We detect the host galaxy in only one LRD, MSAID38108 at z = 4.96, which has a stellar mass of {\mathrm{log}}\,({M}_{* }/{M}_{\odot })=8.6{6}_{-0.23}^{+0.24} , an effective radius of {R}_{e}=0.6{6}_{-0.05}^{+0.08} kpc, and a Sérsic index of n=0.7{1}_{-0.08}^{+0.07} . No host emission centered on the central point source is found in the other seven LRDs. We derive stringent upper limits for the stellar mass of a hypothetical host galaxy by conducting realistic mock simulations that place high-redshift galaxy images under the LRDs. Based on the black hole masses estimated from the broad H α emission line, the derived stellar mass limits are at least a factor of 10 lower than expected from the z ≈ 0 scaling relation between black hole mass and host galaxy stellar mass. Intriguingly, four of the LRDs (50% of the sample) show extended, off-centered emission, which is particularly prominent in the bluer bands. The asymmetric emission of two sources can be modeled as stellar emission, but the nature of the other two is unclear.}, archive = {J_ApJ}, author = {Chang-Hao Chen and Luis C. Ho and Ruancun Li and Ming-Yang Zhuang}, doi = {10.3847/1538-4357/ada93a}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {60}, shortjournal = {The Astrophys. J.}, title = {The host galaxy (If any) of the little red dots}, volume = {983}, year = {2025}, }
• (2025). Deep in the fields of the andromeda halo: Discovery of the pegasus VII dwarf galaxy in UNIONS. ApJ, 983(1), 59. (www)

  @article{ , abstract = {We present the newly discovered dwarf galaxy Pegasus VII (Peg VII), a member of the M31 subgroup which has been uncovered in the ri photometric catalogs from the Ultraviolet Near-Infrared Optical Northern Survey and confirmed with follow-up imaging from both the Canada–France–Hawaii Telescope and the Gemini-North Telescope. This system has an absolute V -band magnitude of −5.7 ± 0.2 mag and a physical half-light radius of 177 {}_{-34}^{+36} pc, which is characteristic of dynamically confirmed Milky Way satellite dwarf galaxies and about 5 times more extended than the most extended M31 globular clusters. Peg VII lies at a three-dimensional separation from M31 of 331 {}_{-4}^{+15} kpc, and a significant elongation ( ∼ 0.5) toward the projected direction of M31 could be indicative of a past tidal interaction, but additional investigation into the orbit, star formation history, and whether any gas remains in the galaxy is needed to better understand the evolution of Peg VII.}, archive = {J_ApJ}, author = {Simon E. T. Smith and Alan W. McConnachie and Stephen Gwyn and Christian R. Hayes and Massimiliano Gatto and Ken Chambers and Jean-Charles Cuillandre and Michael J. Hudson and Eugene Magnier and Nicolas Martin and Julio Navarro}, doi = {10.3847/1538-4357/adb4f3}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {59}, shortjournal = {The Astrophys. J.}, title = {Deep in the fields of the andromeda halo: Discovery of the pegasus VII dwarf galaxy in UNIONS}, volume = {983}, year = {2025}, }
• (2025). Exploring the origin of solar energetic electrons. II. investigating turbulent coronal acceleration. ApJ, 983(1), 58. (www)

  @article{ , abstract = {Nonthermal particle acceleration in the solar corona is evident from both remote hard X-ray sources in the chromosphere and direct in situ detection in the heliosphere. Correlation of spectral indices between remote and in situ energy spectra presents the possibility of a common source-acceleration region within the corona, however the properties and location of this region are not well constrained. To investigate this, we perform a parameter study for both the properties of the ambient plasma of a simulated acceleration region and the turbulent acceleration profile acting on an initially isotropic thermal electron population. We find that independently varying the turbulent acceleration timescale τ acc , acceleration profile standard deviation σ , and acceleration region length L result in an in situ spectral index variation of between 0.5 and 2.0 at 1.0 au for  <100 keV electrons. Short-timescale turbulent scattering in the flaring corona steepens the spectra by ~0.5. It was also found that the in situ spectral index δ derived from the peak electron flux produces a spectral index ~1.6 harder than that from a full-flare X-ray photon flux (of spectral index γ ) simulated with the same intermediate parameters. Previous studies have indicated an approximate δ ≈ γ relationship for selected flares with measured in situ electron and X-ray photon observations, suggesting that an extended source region with nonuniform plasma and/or acceleration properties may be necessary to reproduce this relationship.}, archive = {J_ApJ}, author = {Ross Pallister and Natasha L. S. Jeffrey and Morgan Stores}, doi = {10.3847/1538-4357/adbaf4}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {58}, shortjournal = {The Astrophys. J.}, title = {Exploring the origin of solar energetic electrons. II. investigating turbulent coronal acceleration}, volume = {983}, year = {2025}, }
• (2025). The impacts of bars, spirals, and bulge size on gas-phase metallicity gradients in MaNGA galaxies. ApJ, 983(1), 57. (www)

  @article{ , abstract = {As galaxies evolve over time, the orbits of their constituent stars are expected to change in size and shape, moving stars away from their birth radius. Radial gas flows are also expected. Spiral arms and bars in galaxies are predicted to help drive this radial relocation, and it may be possible to trace this observationally, via a flattening of metallicity gradients. We use data from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey, part of the fourth phase of the Sloan Digital Sky Surveys (SDSS-IV), to look for correlations of the steepness of gas-phase metallicity gradients with various galaxy morphological features (e.g., the presence and pitch angle of spiral arms, the presence of a large scale bar, and bulge size). We select from MaNGA a sample of star-forming galaxies for which gas-phase metallicity trends can be measured and we use morphologies from the Galaxy Zoo survey. We observe that at fixed galaxy mass (1) the presence of spiral structure correlates with steeper gas-phase metallicity gradients; (2) spiral galaxies with larger bulges have both higher gas-phase metallicities and shallower gradients; (3) there is no observable difference in azimuthally averaged radial gradients between barred and unbarred spirals; and (4) there is no observable difference in gradient between tight and loosely wound spirals, but looser-wound spirals have lower average gas-phase metallicity values at fixed mass. We discuss the possible implications of these observational results.}, archive = {J_ApJ}, author = {M. E. Wisz and Karen L. Masters and Kathryne J. Daniel and David V. Stark and Francesco Belfiore}, doi = {10.3847/1538-4357/adbb6f}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {57}, shortjournal = {The Astrophys. J.}, title = {The impacts of bars, spirals, and bulge size on gas-phase metallicity gradients in MaNGA galaxies}, volume = {983}, year = {2025}, }
• (2025). A population synthesis study on the formation of cold jupiters from truncated planetesimal disks. ApJ, 983(1), 56. (www)

  @article{ , abstract = {The occurrence rate of giant planets increases with orbital period and turns over at a location that roughly corresponds to the snowline of solar-type stars. Further, the density distribution of cold Jupiters (CJs) on the semimajor axis–mass diagram shows a relatively steep inner boundary, shaping the desert of warm Jupiters. The eccentricities of CJs show a broad distribution with a decreasing number density toward the larger end. Previous planet formation models fail to reproduce all these features at the same time. We use a planet population synthesis (PPS) model with truncated initial planetesimal distribution and compare the mass and orbital distribution of the simulated planets with the observation. We show that the occurrence of CJs with respect to the orbital period, the slope of the inner boundary of CJs on the semimajor axis–mass diagram, and the eccentricity distribution of CJs agree reasonably well with observations, if CJs form from truncated planetesimal disks of 10 au or wider with suppressed migration. While PPS simulations generally overestimate the fraction of giants with eccentricity below 0.2, N -body simulations produce a more consistent eccentricity distribution with observations. While the fraction of high-eccentricity planets can be increased by widening the planetesimal disk or reducing the migration speed, a deficit of giants with eccentricity between 0.2 and 0.4 exists regardless of the choices of parameters. Our results indicate that CJs are more likely born in truncated disks near the snowline than in classical uniform disks.}, archive = {J_ApJ}, author = {Kangrou Guo and Masahiro Ogihara and Shigeru Ida and Yasunori Hori and Kaiming Cui and Fabo Feng}, doi = {10.3847/1538-4357/adbbe1}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {56}, shortjournal = {The Astrophys. J.}, title = {A population synthesis study on the formation of cold jupiters from truncated planetesimal disks}, volume = {983}, year = {2025}, }
• (2025). JWST spectroscopic view of a rapidly growing, dust-obscured quasar at z ∼ 4: Effect of dust extinction correction on black hole mass and eddington ratio estimation. ApJ, 983(1), 55. (www)

  @article{ , abstract = {In the merger-driven galaxy evolution scenario, the central supermassive black holes (SMBHs) in dust-obscured galaxies grow rapidly. Interestingly, a recent work on a dust-obscured galaxy, LID-568 at z = 3.965, has shown that its SMBH is growing extremely fast at about 40 times the Eddington-limited accretion rate (i.e., super-Eddington accretion). However, the heavy dust extinction of the host galaxy could affect the result if not corrected properly. Here, we analyze James Webb Space Telescope (JWST) NIRSpec integral field unit (IFU) and MIRI spectra of LID-568. By measuring its bolometric luminosity ( L bol ) and black hole (BH) mass ( M BH ) using an extinction-free estimator based on mid-infrared spectra, we obtain L bol = 10 46.83±0.07 erg s −1 and M BH = 10 8.43±0.15 M ⊙ . The measured Eddington ratio ( λ Edd ) is 1.97 ± 0.88, consistent with the accretion rate at the Eddington limit; in other words, it is not super-Eddington in a significant manner. This result underscores challenges and the importance of carefully considering dust extinction when analyzing the BH growth in dust-obscured quasars.}, archive = {J_ApJ}, author = {Dohyeong Kim and Myungshin Im}, doi = {10.3847/1538-4357/adbd44}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {55}, shortjournal = {The Astrophys. J.}, title = {JWST spectroscopic view of a rapidly growing, dust-obscured quasar at z ∼ 4: Effect of dust extinction correction on black hole mass and eddington ratio estimation}, volume = {983}, year = {2025}, }
• (2025). The relative constraining power of the high-z 21 cm dipole and monopole signals. ApJ, 983(1), 54. (www)

  @article{ , abstract = {The 21 cm background is a promising probe of early star formation and black hole activity. While a slew of experiments on the ground seek to detect the 21 cm monopole and spatial fluctuations on large ∼10' scales, little work has been done on the prospects for detecting the 21 cm dipole signal or its utility as a probe of early galaxies. Though an intrinsically weak signal relative to the monopole, its direction is known well from the cosmic microwave background and wide-field surveys; furthermore, as a relative measurement the dipole could help relax instrumental requirements. In order to understand the constraining power of the dipole, in this work we perform parameter inference on mock data sets that include the dipole, the monopole, or both signals. We find that while the monopole does provide the best constraints for a given integration time, constraints from a dipole measurement are competitive and can in principle constrain the cosmic star formation rate density and efficiency of X-ray photon production in early z ∼ 15 galaxies to better than a factor of ∼2. This result holds for most of the available prior volume, which is set by constraints on galaxy luminosity functions, the reionization history, and upper limits from 21 cm power spectrum experiments. We also find that predictions for the monopole from a dipole measurement are robust to different choices of signal model. As a result, the 21 cm dipole signal is a valuable target for future observations and offers a robust cross-check on monopole measurements.}, archive = {J_ApJ}, author = {Jordan Mirocha and Chris Anderson and Tzu-Ching Chang and Olivier Doré and Adam Lidz}, doi = {10.3847/1538-4357/adbdce}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {54}, shortjournal = {The Astrophys. J.}, title = {The relative constraining power of the high-z 21 cm dipole and monopole signals}, volume = {983}, year = {2025}, }
• (2025). Detection of the optical counterpart of the transient ULX NGC 300 ULX-1: A nascent black hole-neutron star binary?. ApJ, 983(1), 53. (www)

  @article{ , abstract = {The endpoints of massive star evolution are poorly known, especially those in interacting binary systems containing compact objects, such as neutron stars or black holes (BHs). Such systems are bright in X-rays, and the most luminous among them are called ultra-luminous X-ray sources (ULXs). In this paper, we address the enigmatic NGC 300 ULX-1. Its X-ray activity started in 2010 with the supernova impostor-like event SN 2010da. In the following few years, the ULX was powered by persistent super-Eddington accretion but then it dimmed in X-rays. We present the most recent X-ray and optical observations. The Chandra and Swift telescopes confirm that SN 2010da/NGC 300 ULX-1 is not accreting at the super-Eddington level anymore. We attribute this switch in accretion regime to the donor star variability and its fast evolution. In order to gain a better understanding of the donor star's nature, we consider its optical light curve on a decade-long timescale and show that the optical counterpart of SN 2010da/NGC 300 ULX-1 dimmed significantly over recent years. The most recent detection in the optical by the Gemini telescope reveals that the source is now >2.5 mag fainter in the {r}^{{\prime} } band compared to the epoch when it was spectroscopically classified as a red supergiant. We discuss the nature of the abrupt changes in the donor star properties and consider, among other possibilities, the silent collapse of the donor star into a BH.}, archive = {J_ApJ}, author = {André-Nicolas Chené and Georgios Vasilopoulos and Lidia M. Oskinova and Clara Martínez-Vázquez}, doi = {10.3847/1538-4357/adbe78}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {53}, shortjournal = {The Astrophys. J.}, title = {Detection of the optical counterpart of the transient ULX NGC 300 ULX-1: A nascent black hole-neutron star binary?}, volume = {983}, year = {2025}, }
• (2025). The infrared traced star formation rates of associated absorption lines quasars. ApJ, 983(1), 52. (www)

  @article{ , abstract = {Some optically selected quasars exhibit Mg ii- associated absorption lines (AALs), and their origin remains unclear. In this paper, we compile a sample of 1769 quasars, with or without Mg ii AALs, of which 1689 are far-infrared (FIR) detected quasars and the rest are not detected in FIR. For the FIR undetected quasars, we obtain stacks for both with and without Mg ii AAL quasars. Then, we estimate the star formation rates (SFRs) within quasar host galaxies based on their FIR luminosities derived from their FIR graybody components, and find that, although quasars with Mg ii AALs have significantly redder median composite spectra than those without Mg ii AALs, the SFR distributions of the two types of quasars are statistically indistinguishable. These results do not require an evolutionary link between the quasars with and without Mg ii AALs, and would be reconciled if an orientation effect cannot be ignored among the quasars hosting different types of absorption lines.}, archive = {J_ApJ}, author = {Zhe-Geng Chen and Rui-Jing Lu and Zhi-Fu Chen and Wen-Qiang Liang and Xing-Long Peng and Jing Li and Wei-Rong Huang}, doi = {10.3847/1538-4357/adbf1c}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {52}, shortjournal = {The Astrophys. J.}, title = {The infrared traced star formation rates of associated absorption lines quasars}, volume = {983}, year = {2025}, }
• (2025). The vertical metallicity gradient of the galactic disk for mono-age stellar populations in LAMOST. ApJ, 983(1), 51. (www)

  @article{ , abstract = {The vertical metallicity gradient of the Galactic disk offers valuable insights into the disk's formation and chemical evolution over time. We utilized the Large Sky Area Multi-Object Fibre Spectroscopic Telescope low-resolution spectral young stellar sample to investigate this gradient and found that it approaches zero as stellar effective temperature (or age) increases (or decreases) across various Galactocentric distances. To validate this result, we analyzed 295 open clusters younger than 3 Gyr and 976 classical cepheids within the Galactic disk. The findings confirmed that, within a given narrow age range, the vertical metallicity gradient is effectively zero. This relationship between metallicity and age supports the "upside-down" disk formation theory, as it indicates that the youngest and most metal-rich stars dominate the midplane, while older and more metal-poor stars formed at larger vertical heights and currently tend to be at these heights. Overall, our results align well with theoretical predictions, offering further insight into the chemical evolution and structural properties of the Milky Way.}, archive = {J_ApJ}, author = {Gaohuan Long and Haibo Yuan and Shuai Xu and Chun Wang and Ruoyi Zhang and Bowen Huang}, doi = {10.3847/1538-4357/adbf93}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {51}, shortjournal = {The Astrophys. J.}, title = {The vertical metallicity gradient of the galactic disk for mono-age stellar populations in LAMOST}, volume = {983}, year = {2025}, }
• (2025). Constraints on dark matter self-interactions from weak lensing of galaxies from the dark energy survey around clusters from the atacama cosmology telescope survey. ApJ, 983(1), 50. (www)

  @article{ , abstract = {Self-interactions of dark matter particles impact the distribution of dark matter in halos. The exact nature of the self-interactions can lead to either expansion or collapse of the core within the halo lifetime, leaving distinctive signatures in the dark matter distributions not only at the halo center but throughout the virial region. Optical galaxy surveys, which precisely measure the weak lensing of background galaxies by massive foreground clusters, allow us to directly measure the matter distribution within clusters and probe subtle effects of self-interacting dark matter (SIDM) throughout the halo's full radial range. We compare the weak-lensing measurements reported by T. Shin et al., which use lens clusters identified by the Atacama Cosmology Telescope Survey and source galaxies from the Dark Energy Survey, with predictions from SIDM models having either elastic or dissipative self-interactions. To model the weak-lensing observables, we use cosmological N -body simulations for elastic self-interactions and semianalytical fluid simulations for dissipative self-interactions. We find that current weak-lensing measurements already constrain the isotropic and elastic SIDM to a cross section per mass of σ / m < 1 cm 2 g −1 at a 95% confidence level for clusters with mean M 200m = 3 × 10 14 M ⊙ h –1 . The same measurements also impose novel constraints on the energy loss per unit mass for dissipative SIDM. Upcoming surveys are anticipated to enhance the signal-to-noise ratio of weak-lensing observables significantly, making them effective tools for investigating the nature of dark matter, including self-interactions, through weak lensing.}, archive = {J_ApJ}, author = {Susmita Adhikari and Arka Banerjee and Bhuvnesh Jain and Tae-hyeon Shin and Yi-Ming Zhong}, doi = {10.3847/1538-4357/adb0c4}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {50}, shortjournal = {The Astrophys. J.}, title = {Constraints on dark matter self-interactions from weak lensing of galaxies from the dark energy survey around clusters from the atacama cosmology telescope survey}, volume = {983}, year = {2025}, }
• (2025). Core revelations: The star formation and active galactic nucleus connection at the heart of NGC 7469. ApJ, 983(1), 49. (www)

  @article{ , abstract = {We investigate the star formation–active galactic nucleus (AGN) connection in the Seyfert 1 NGC 7469 using James Webb Space Telescope mid-infrared spectroscopic integral field unit (IFU) data. We use the IFU data to generate maps of different emission lines present in the spectrum, such as the star formation (SF) tracer [Ne ii ] 12.81 μ m and the AGN tracer [Ne v ] 14.32 μ m. We can separate the AGN- and SF-dominated regions using spatially resolved mid-infrared diagnostic diagrams, and we further investigate the ionization sources powering each region by constructing photoionization models. We find that the previously detected eastern wind populates an intermediary region of the diagrams, between our star-forming and AGN points. Although it is possible that the star-forming ring may inherently not be uniform, this wind also coincides with a reduction in the [Ne ii ] emission in the ring, which suggests that the ionization cone intersects the ring in this direction.}, archive = {J_ApJ}, author = {Léa M. Feuillet and Steve Kraemer and Marcio B. Meléndez and Travis C. Fischer and Henrique R. Schmitt and James N. Reeves and Anna Trindade Falcão}, doi = {10.3847/1538-4357/adb155}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {49}, shortjournal = {The Astrophys. J.}, title = {Core revelations: The star formation and active galactic nucleus connection at the heart of NGC 7469}, volume = {983}, year = {2025}, }
• (2025). The birth of a major coronal mass ejection with intricate magnetic structure from multiple active regions. ApJ, 983(1), 48. (www)

  @article{ , abstract = {Coronal mass ejections (CMEs) are the eruptions of magnetized plasma from the Sun and are considered the main driver of adverse space weather events. Hence, understanding their formation process, particularly the magnetic topology, is critical for accurate space weather prediction. Here, based on imaging observations and three-dimensional (3D) data-constrained thermodynamic magnetohydrodynamic (MHD) simulation in spherical coordinates, we exhibit the birth of a CME with intricate magnetic structure from multiple active regions (ARs) due to 3D magnetic reconnection. It is observed as a coronal jet between ARs, accompanied by the back-flowing of filament materials along the jet spine after the passage of the eruptive filament. This jet connects two dimming regions within different ARs. This is an observational proxy of 3D magnetic reconnection between the CME flux rope and the null-point magnetic field lines crossing ARs. Hereafter, the thermodynamic data-constrained MHD simulation successfully reproduces the observed jet and the reconnection process that flux ropes partake in, leading to a CME flux rope with a complex magnetic structure distinct from its progenitor. The generality of this scenario is then validated by data-inspired MHD simulations in a simple multipolar magnetic configuration. This work demonstrates the role of multiple ARs in forming CMEs with intricate magnetic structures. On the one hand, a noncoherent flux rope where not all twisted magnetic field lines wind around one common axis is naturally formed. On the other hand, our findings suggest that the topology of a real CME flux rope may not be solely determined by a single AR, particularly during periods of solar maximum.}, archive = {J_ApJ}, author = {J. H. Guo and Y. W. Ni and B. Schmieder and Y. Guo and C. Xia and P. Devi and R. Chandra and S. Poedts and R. Joshi and Y. H. Zhou and H. T. Li and P. F. Chen}, doi = {10.3847/1538-4357/adb976}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {48}, shortjournal = {The Astrophys. J.}, title = {The birth of a major coronal mass ejection with intricate magnetic structure from multiple active regions}, volume = {983}, year = {2025}, }
• (2025). The massive and distant clusters of WISE survey. XII. exploring X-ray active galactic nuclei in dynamically active massive galaxy clusters at z ∼ 1. ApJ, 983(1), 47. (www)

  @article{ , abstract = {We present an analysis of the cluster X-ray morphology and active galactic nucleus (AGN) activity in nine z ∼ 1 galaxy clusters from the Massive and Distant Clusters of WISE Survey observed with Chandra. Using photon asymmetry ( A phot ) to quantify X-ray morphologies, we find evidence that the four most dynamically disturbed clusters are likely to be mergers. Employing a luminosity cut of 7.6 × 10 42 erg s −1 to identify AGNs in the 0.7–7.0 keV region, we show that the majority of these clusters host excess AGNs compared to the local field. We use the model of cumulative number counts ( \mathrm{log}N-\mathrm{log}S ) to predict AGN incidence in cluster isophotes under this luminosity cut. Our analysis finds evidence (at >2 σ ) of a positive correlation between AGN surface densities and photon asymmetry, suggesting that a disturbed cluster environment plays a pivotal role in regulating triggering of AGNs. Studying AGN incidence in cluster X-ray isophotes equivalent in area to 1.0 r 500 , we find that the AGN space density inversely scales with cluster mass as \sim {M}^{-0.{5}_{-0.18}^{+0.18}} at the 3.18 σ level. Finally, when we separately explore the cluster mass dependence of excess AGN surface density in disturbed and relaxed clusters, we see tentative evidence that the two morphologically distinct subpopulations exhibit diverging trends, especially near the outskirts, likely due to cluster merger-driven AGN triggering/suppression.}, archive = {J_ApJ}, author = {Mustafa Muhibullah and Mark Brodwin and Michael McDonald and Anthony H. Gonzalez and Emily Moravec and Thomas Connor and S. A. Stanford and Taweewat Somboonpanyakul and Florian Ruppin and Peter R. M. Eisenhardt and Bandon Decker and Daniel Stern and Ariane Trudeau}, doi = {10.3847/1538-4357/adbae4}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {47}, shortjournal = {The Astrophys. J.}, title = {The massive and distant clusters of WISE survey. XII. exploring X-ray active galactic nuclei in dynamically active massive galaxy clusters at z ∼ 1}, volume = {983}, year = {2025}, }
• (2025). Constraining baryonic feedback effects on the matter power spectrum with fast radio bursts. ApJ, 983(1), 46. (www)

  @article{ , abstract = {In the age of large-scale galaxy and lensing surveys, such as DESI, Euclid, Roman, and Rubin, we stand poised to usher in a transformative new phase of data-driven cosmology. To fully harness the capabilities of these surveys, it is critical to constrain the poorly understood influence of baryon feedback physics on the matter power spectrum. We investigate the use of a powerful and novel cosmological probe, fast radio bursts (FRBs), to capture baryonic effects on the matter power spectrum, leveraging simulations from the Cosmology and Astrophysics with MachinE Learning Simulations (or CAMELS) project, including IllustrisTNG, SIMBA, and Astrid. We find that FRB statistics exhibit a strong correlation, independent of the subgrid model and cosmology, with quantities known to encapsulate baryonic impacts on the matter power spectrum, such as baryon spread and the halo baryon fraction. We propose an innovative method utilizing FRB observations to quantify the effects of feedback physics and enhance weak-lensing measurements of S 8 . We outline the necessary steps to prepare for the imminent detection of large FRB populations in the coming years, focusing on understanding the redshift evolution of FRB observables and mitigating the effects of cosmic variance.}, archive = {J_ApJ}, author = {Isabel Medlock and Daisuke Nagai and Daniel Anglés-Alcázar and Matthew Gebhardt}, doi = {10.3847/1538-4357/adbc9c}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {46}, shortjournal = {The Astrophys. J.}, title = {Constraining baryonic feedback effects on the matter power spectrum with fast radio bursts}, volume = {983}, year = {2025}, }
• (2025). Seoul national university AGN monitoring project. v. velocity-resolved hβ reverberation mapping and evidence of kinematics evolution. ApJ, 983(1), 45. (www)

  @article{ , abstract = {We present velocity-resolved reverberation lags of H β for 20 active galactic nuclei (AGNs) from the Seoul National University AGN Monitoring Project. We detect unambiguous velocity-resolved structures in 12 AGNs, among which eight objects exhibit symmetric structures, two objects show inflow-like characteristics, and two objects display outflow-like signatures. For two AGNs, we successfully measure the velocity-resolved lags in different years, revealing evidence of evolving broad-line region (BLR) kinematics. By combining our sample with the literature velocity-resolved lags, we find that the symmetric velocity-resolved lags are the most common (40%) type among this sample. The frequency of inflow kinematics is also notable (20%), while outflow kinematics are less common (11%). Our sample significantly expands the previous velocity-resolved reverberation mapping sample in the high-luminosity regime, enabling us to constrain BLR kinematics across a large dynamic range of luminosity.}, archive = {J_ApJ}, author = {Shu Wang and Jong-Hak Woo and Aaron J. Barth and Vardha N. Bennert and Elena Gallo and Edmund Hodges-Kluck and Minjin Kim and Suvendu Rakshit and Tommaso Treu and Hojin Cho and Kyle M. Kabasares and Matthew A. Malkan and Amit Kumar Mandal and Donghoon Son and Vivian U and Lizvette Villafana}, doi = {10.3847/1538-4357/adbca5}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {45}, shortjournal = {The Astrophys. J.}, title = {Seoul national university AGN monitoring project. v. velocity-resolved hβ reverberation mapping and evidence of kinematics evolution}, volume = {983}, year = {2025}, }
• (2025). Radio pulse search from aql X-1. ApJ, 983(1), 44. (www)

  @article{ , abstract = {We present 12 observations of the accreting millisecond X-ray pulsar Aql X-1, taken from 2022 August to 2023 October using the Five-hundred-meter Aperture Spherical Radio Telescope at 1250 MHz. These observations covered both the quiescence and X-ray outburst states, as determined by analyzing the X-ray data from the Neutron Star Interior Composition Explorer and the Monitor of All-sky X-ray Image. Periodicity and single-pulse searches were conducted for each observation, but no pulsed signals were detected. The obtained upper limit flux densities are in the range of 2.86−5.73 μ Jy, which provide the lowest limits to date. We discuss several mechanisms that may prevent detection, suggesting that Aql X-1 may be in the radio-ejection state during quiescence, where the radio pulsed emissions are absorbed by the matter surrounding the system.}, archive = {J_ApJ}, author = {Long Peng and Zhaosheng Li and Yuanyue Pan and Shanshan Weng and Wenming Yan and Na Wang and Bo-Jun Wang and Shuangqiang Wang}, doi = {10.3847/1538-4357/adbd43}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {44}, shortjournal = {The Astrophys. J.}, title = {Radio pulse search from aql X-1}, volume = {983}, year = {2025}, }
• (2025). Rapid rotation of polarization orientations in PSR b1919+21’s single pulses: Implications on pulsar’s magnetospheric dynamics. ApJ, 983(1), 43. (www)

  @article{ , abstract = {We analyze and model rapid rotations of polarization orientations in PSR B1919+21's single pulses based on Five-hundred-meter Aperture Spherical radio Telescope observation data. In more than one-third of B1919+21's single pulses, the polarization position angle (PA) is found to rotate quasi-monotonically with pulse longitude over 180° or even 360°. Some single pulse PA even rotates by over 540°. Most of these quasi-monotonic PA curves have negative slopes with respect to pulse longitude. Oscillations of circular polarization fraction accompany these PA rotations. This rapid rotation could be induced by a quick change of phase lag between two normal wave modes within an individual pulse. We propose a phenomenological model to reproduce the observed polarization rotations in single pulses, and calculate phase lags in a dipolar magnetic field of an aligned rotating pulsar, with a dispersion relation of orthogonal wave modes in strongly magnetized electron-positron plasma. According to the dispersion relation, the weak frequency dependence of observed polarization rotation requires small angles between the radio wavevector and local magnetic fields, which requires the radio emission height to be low, on the order of 10 times neutron star radius.}, archive = {J_ApJ}, author = {Shunshun Cao and Jinchen Jiang and Jaroslaw Dyks and Kejia Lee and Jiguang Lu and Lucy S. Oswald and Weiyang Wang and Renxin Xu}, doi = {10.3847/1538-4357/adbe33}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {43}, shortjournal = {The Astrophys. J.}, title = {Rapid rotation of polarization orientations in PSR b1919+21’s single pulses: Implications on pulsar’s magnetospheric dynamics}, volume = {983}, year = {2025}, }
• (2025). Nonlinear evolution of the Kelvin–Helmholtz instability in the presence of radiation and parallel magnetic fields. ApJ, 983(1), 42. (www)

  @article{ , abstract = {The evolution of Kelvin–Helmholtz (KH) instability in the Orion Nebula is studied using a two-dimensional radiation magnetohydrodynamic (MHD) simulation in the presence of the in-plane magnetic field parallel to the flow direction. The linear results show that the parallel component of the magnetic field can stabilize the instability due to the increase of the field line tension, while the radiation field leads to the reduced compressibility of the system and enhances the growth of the instability. When the interface is subjected to more radiation pressure, it is found that a greater saturation magnetic energy is produced, and there is a transfer of the kinetic energy to the thermal energy in the nonlinear evolution of the KH instability. The radiation pressure also accelerates the development of instability at the interface, resulting in a large vortex structure in the nonlinear phase. The results also reveal the relaxation mechanism of the velocity profile caused by momentum transport in the nonlinear phase. The complete evolution of the KH instability as the result of a combination of dynamo effects and energy release is also discussed. Based on these results, a preliminary discussion of several events observed in star-forming regions is given.}, archive = {J_ApJ}, author = {Hang Peng and Fang Yu and Guangzhi Ren and Lai Wei and Zheng-Xiong Wang and Yue Liu}, doi = {10.3847/1538-4357/adbe64}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {42}, shortjournal = {The Astrophys. J.}, title = {Nonlinear evolution of the Kelvin–Helmholtz instability in the presence of radiation and parallel magnetic fields}, volume = {983}, year = {2025}, }
• (2025). Lagrangian perturbation theory for biased tracers: Significance of the number conservation. ApJ, 983(1), 41. (www)

  @article{ , abstract = {The Lagrangian perturbation theory provides a simple yet powerful way of computing the nonlinear matter power spectrum, and it has been applied to biased tracers such as halos and galaxies. The number conservation of matter particles allows a simple relation between the fluctuations at the initial and late times, which is essential in deriving the exact expression for the nonlinear matter power spectrum. Here, we investigate the significance of the number conservation in the Lagrangian perturbation theory for biased tracers. We use N -body simulations to test the significance of the number conservation, by tracing dark matter halo samples in time. For the mass-bin sample {\rm{\Delta }}\,{\mathrm{log}}\,{M}_{h}\,({h}^{-1}{M}_{\odot })=0.5 at z ≃ 3, the theoretical predictions for the halos overestimate the power spectrum at z = 0 by a factor of 3, while the simulation results match the theoretical predictions if the number conservation of halos is imposed in the simulations throughout the evolution. Starting with a halo sample at z = 0 as another test, we trace back in time the particles that belong to the halos at z = 0 and use their center-of-mass positions as halo positions at z > 0. The halo power spectra at z > 0 from the simulations agree with the theoretical predictions of the Lagrangian perturbation theory. This numerical experiment proves that the number conservation is crucial in the Lagrangian perturbation theory predictions. We discuss the implications for various applications of the Lagrangian perturbation theory for biased tracers.}, archive = {J_ApJ}, author = {Peter Espenshade and Jaiyul Yoo}, doi = {10.3847/1538-4357/adbe69}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {41}, shortjournal = {The Astrophys. J.}, title = {Lagrangian perturbation theory for biased tracers: Significance of the number conservation}, volume = {983}, year = {2025}, }
• (2025). Radiation transport simulations of quasiperiodic eruptions from Star–Disk collisions. ApJ, 983(1), 40. (www)

  @article{ , abstract = {Periodic collisions between a star on an inclined orbit around a supermassive black hole and its accretion disk offer a promising explanation for X-ray "quasiperiodic eruptions" (QPEs). Each passage through the disk midplane shocks and compresses gas ahead of the star, which subsequently re-expands above the disk as a quasi-spherical cloud. We present spherically symmetric Monte Carlo radiation transport simulations that follow the production of photons behind the radiation-mediated shock, Comptonization by hot electrons, and the eventual escape of the radiation through the expanding debris. Such 1D calculations are approximately justified for thin disks (scale-height h ≲ few × R ⋆ ), through which the star of radius R ⋆ passes more quickly than the shocked gas can flow around the star. For collision speeds v coll ≳ 0.15 c and disk surface densities Σ ∼ 10 3 g cm −2 characteristic of those encountered by stellar orbits consistent with QPE recurrence times, the predicted transient light curves exhibit peak luminosities ≳10 42 erg s −1 and Comptonized quasi-thermal (Wien-like) spectra that peak at energies hν ∼ 100 eV, which is broadly consistent with QPE properties. For these conditions, gas and radiation are out of equilibrium, rendering the emission temperature harder than the blackbody value due to inefficient photon production behind the radiation-mediated shock. The predicted eruptions execute counterclockwise loops in hardness–luminosity space, qualitatively similar to QPE observations. Reproducing the observed eruption properties (duration, luminosity, temperature) requires a large radius R ⋆ ≳ 10 R ⊙ , which may point to inflation of the star's atmosphere from repeated collisions.}, archive = {J_ApJ}, author = {Indrek Vurm and Itai Linial and Brian D. Metzger}, doi = {10.3847/1538-4357/adb74d}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {40}, shortjournal = {The Astrophys. J.}, title = {Radiation transport simulations of quasiperiodic eruptions from Star–Disk collisions}, volume = {983}, year = {2025}, }
• (2025). Mass transfer in eccentric orbits with self-consistent stellar evolution. ApJ, 983(1), 39. (www)

  @article{ , abstract = {We investigate Roche lobe overflow mass transfer (MT) in eccentric binary systems between stars and compact objects (COs), modeling the coupled evolution of both the star and the orbit due to eccentric MT (eMT) in a self-consistent framework. We implement the analytic expressions for secular rates of change of the orbital semimajor axis and eccentricity, assuming a delta function MT at periapse, in the binary stellar evolution code MESA . Two scenarios are examined: (1) a simplified model isolating the effects of eMT on stellar and orbital evolution, and (2) realistic binary configurations that include angular momentum exchange (e.g., tides, mass loss, spin–orbit coupling, and gravitational-wave (GW) radiation). Unlike the ad hoc approach of instant circularization that is often employed, explicit modeling of eMT reveals that a large fraction of binaries can remain eccentric post-MT. Even binaries that naturally circularize during eMT have different properties (donor mass and orbital size) compared to predictions from instant circularization, with some showing fundamentally different evolutionary outcomes (e.g., stable vs. unstable MT). We demonstrate that a binary's initial mass ratio and eccentricity are predictive of whether it will remain eccentric or circularize after eMT. These findings underscore the importance of eMT in understanding CO-hosting binary populations, including X-ray binaries, GW sources, and other high-energy transients.}, archive = {J_ApJ}, author = {Kyle Akira Rocha and Rachel Hur and Vicky Kalogera and Seth Gossage and Meng Sun and Zoheyr Doctor and Jeff J. Andrews and Simone S. Bavera and Max M. Briel and Tassos Fragos and Konstantinos Kovlakas and Matthias U. Kruckow and Devina Misra and Zepei Xing and Emmanouil Zapartas}, doi = {10.3847/1538-4357/adb970}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {39}, shortjournal = {The Astrophys. J.}, title = {Mass transfer in eccentric orbits with self-consistent stellar evolution}, volume = {983}, year = {2025}, }
• (2025). Data-constrained magnetohydrodynamic simulation for magnetic flux rope eruptions driven by magnetic reconnection. ApJ, 983(1), 38. (www)

  @article{ , abstract = {We conducted data-constrained magnetohydrodynamic (MHD) simulations for solar active region (AR) NOAA AR 11429, which produced two X-class flares within a span of 63 minutes. The simulations were performed using the zero- β MHD approximation, with the initial condition derived from the nonlinear force-free field extrapolated from the photospheric magnetograms taken 2 hr before the first X5.4 flare. During the simulation, we enhanced magnetic reconnection locally by applying anomalous resistivity in the induction equation within the regions of interest. As a result, the simulations successfully reproduced the expansion of two magnetic flux ropes (MFRs) corresponding to the two observed eruptions. The result shows that the difference in stability between the two MFRs is related to the location of the magnetic reconnection that triggers the solar eruptions. Furthermore, comparison with the analysis of failed MFR eruptions indicates that both the initiation reconnection and the subsequent driving mechanism, torus instability, are equally important for a successful eruption. This simulation reveals a new mechanism in which long loops, formed via tether-cutting reconnection, push up the overlying twisted field lines, leading to their destabilization by torus instability.}, archive = {J_ApJ}, author = {Nian Liu and Satoshi Inoue and Ying Wang and Haimin Wang}, doi = {10.3847/1538-4357/adba56}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {38}, shortjournal = {The Astrophys. J.}, title = {Data-constrained magnetohydrodynamic simulation for magnetic flux rope eruptions driven by magnetic reconnection}, volume = {983}, year = {2025}, }
• (2025). Digging into the interior of hot cores with ALMA (DIHCA). v. deuterium fractionation of methanol. ApJ, 983(1), 37. (www)

  @article{ , abstract = {We have observed the 13 CH 3 OH 5 1 −4 1 A + , 13 CH 3 OH 14 1 −13 2 A − , and CH 2 DOH 8 2,6 −8 1,7 e 0 lines toward 24 high-mass star-forming regions by using Atacama Large Millimeter/submillimeter Array with an angular resolution of about 0 \mathop{.}\limits^{\unicode{x02033}} 3. This resolution corresponds to a linear scale of 400–1600 au, allowing us to resolve individual cores properly. We detected the 13 CH 3 OH and CH 2 DOH emission near the continuum peaks in many of these regions. From the two 13 CH 3 OH lines, we calculated the temperature toward the 13 CH 3 OH peaks, and confirm that the emission traces hot (>100 K) regions. The N(CH 2 DOH)/N( 12 CH 3 OH) ratio in the observed high-mass star-forming regions is found to be lower than that in low-mass star-forming regions. We have found no correlation between the N(CH 2 DOH)/N( 13 CH 3 OH) or N(CH 2 DOH)/N( 12 CH 3 OH) ratios and either temperatures or distance to the sources, and have also found a source-to-source variation in these ratios. Our model calculations predict that the N(CH 2 DOH)/N( 12 CH 3 OH) ratio in hot cores depends on the duration of the cold phase; the shorter the cold phase, the lower the deuterium fractionation in the hot cores. We have suggested that the lower N(CH 2 DOH)/N( 12 CH 3 OH) ratio in high-mass star-forming regions compared to that in low-mass star-forming regions is due to the shorter duration of the cold phase and that the diversity in the N(CH 2 DOH)/N( 12 CH 3 OH) ratio in high-mass star-forming regions is due to the diversity in the length of the cold prestellar phase, and not the time that the objects have been in the hot core phase.}, archive = {J_ApJ}, author = {Takeshi Sakai and Nobuhito Shiomura and Patricio Sanhueza and Kenji Furuya and Fernando A. Olguin and Ken’ichi Tatematsu and Yuri Aikawa and Kotomi Taniguchi and Huei-Ru Vivien Chen and Kaho Morii and Fumitaka Nakamura and Shanghuo Li and Xing Lu and Qizhou Zhang and Tomoya Hirota and Kousuke Ishihara and Hongda Ke and Nami Sakai and Satoshi Yamamoto}, doi = {10.3847/1538-4357/adba5a}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {37}, shortjournal = {The Astrophys. J.}, title = {Digging into the interior of hot cores with ALMA (DIHCA). v. deuterium fractionation of methanol}, volume = {983}, year = {2025}, }
• (2025). On the extremely X-ray variable active galactic nuclei in the XMM-LSS field. ApJ, 983(1), 36. (www)

  @article{ , abstract = {We present a systematic investigation of extremely X-ray variable active galactic nuclei (AGNs) in the ≈5.3 deg 2 XMM-SERVS XMM-LSS region. Eight variable AGNs are identified with rest-frame 2 keV flux density variability amplitudes around 6–12. We comprehensively analyze the X-ray and multiwavelength data to probe the origin of their extreme X-ray variability. It is found that their extreme X-ray variability can be ascribed to changing accretion state or changing obscuration from dust-free absorbers. For five AGNs, their X-ray variability is attributed to changing accretion state, supported by contemporaneous multiwavelength variability and the absence of X-ray absorption in the low-state spectra. With new Multiple Mirror Telescope (MMT) spectra for four of these sources, we confirm one changing-look AGN. One MMT AGN lacks multiepoch spectroscopic observations, while the other two AGNs do not exhibit changing-look behavior, likely because the MMT observations did not capture their high states. The X-ray variability of the other three AGNs is explained by changing obscuration, and they show only mild long-term optical/IR variability. The absorbers of these sources are likely clumpy accretion-disk winds, with variable column densities and covering factors along the lines of sight.}, archive = {J_ApJ}, author = {Zijian Zhang and Bin Luo and Linhua Jiang and W. N. Brandt and Jian Huang and Qingling Ni}, doi = {10.3847/1538-4357/adbb6b}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {36}, shortjournal = {The Astrophys. J.}, title = {On the extremely X-ray variable active galactic nuclei in the XMM-LSS field}, volume = {983}, year = {2025}, }
• (2025). Follow-up of neutron star mergers with CTA and prospects for joint detection with gravitational-wave detectors. ApJ, 983(1), 35. (www)

  @article{ , abstract = {The joint gravitational wave (GW) and electromagnetic observations of the binary neutron star (BNS) merger GW170817 marked a giant leap in multimessenger astrophysics. The extensive observation campaign of the associated gamma-ray burst (GRB) and its afterglow has strengthened the hypothesis associating GRBs with BNS mergers and provided insights into mass ejection, particularly the relativistic outflow launched in BNS mergers. In this paper, we investigate the joint detection probabilities of BNS mergers by GW detectors and the upcoming ground-based very-high-energy (VHE) γ -ray instrument, the Cherenkov Telescope Array (CTA). Using an empirical relation that constrains the distance–inclination angle plane, we simulated BNS mergers detectable in the O5 run of the LIGO/Virgo/Kagra network with a 300 Mpc BNS horizon. Assuming Gaussian structured jets and ignoring the large sky localization challenges of GW detectors, we estimated probability of detection of the VHE afterglow by CTA. We have explored the afterglow parameter space to identify conditions favourable for detecting synchrotron self-Compton emission by CTA. Our study reveals that events viewed at angles ≲3 times the jet core angle are detectable by CTA when the initial bulk Lorentz factor at the jet axis ranges between 100 and 800. We find high kinetic energy ( E k > 10 50 erg), ambient density ( n 0 > 10 −1 cm −3 ), and energy content in nonthermal electrons significantly enhance the likelihood of CTA detection within 300 Mpc. The joint detection rate varies significantly with afterglow parameter distributions, ranging from 0.003 to 0.5 per year.}, archive = {J_ApJ}, author = {T. Mondal and S. Chakraborty and L. Resmi and D. Bose}, doi = {10.3847/1538-4357/adbd12}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {35}, shortjournal = {The Astrophys. J.}, title = {Follow-up of neutron star mergers with CTA and prospects for joint detection with gravitational-wave detectors}, volume = {983}, year = {2025}, }
• (2025). Subphotospheric emission from short gamma-ray bursts. II. signatures of nonthermal dissipation in the multi-messenger signals. ApJ, 983(1), 34. (www)

  @article{ , abstract = {Building on a general relativistic magnetohydrodynamic simulation of a short gamma-ray burst (sGRB) jet with initial magnetization σ 0 = 150, propagating through the dynamical ejecta from a binary neutron star merger, we identify regions of energy dissipation driven by magnetic reconnection and collisionless subshocks within different scenarios. We solve the transport equations for photons, electrons, protons, neutrinos, and intermediate particles up to the photosphere, accounting for all relevant radiative processes, including electron and proton acceleration, and investigate the potential impact of magnetic reconnection occurring in different regions along the jet. We find the photon spectra undergo nonthermal modifications below the photosphere, observable in both on-axis and off-axis emission directions, as well as across different scenarios of energy dissipation and subsequent particle acceleration. Interestingly, the spectral index of the photon energy distribution can vary at most by ∼20% across all different dissipation scenarios. Depending on the dissipation mechanism at play, neutrino signatures may accompany the photon signal, pointing to efficient proton acceleration and shedding light on jet physics. Although our findings are based on one jet simulation, they point to a potential universal origin of the nonthermal features of the Band spectrum observed in sGRBs.}, archive = {J_ApJ}, author = {Annika Rudolph and Irene Tamborra and Ore Gottlieb}, doi = {10.3847/1538-4357/adbd3e}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {34}, shortjournal = {The Astrophys. J.}, title = {Subphotospheric emission from short gamma-ray bursts. II. signatures of nonthermal dissipation in the multi-messenger signals}, volume = {983}, year = {2025}, }
• (2025). Two phases of particle acceleration of a solar flare associated with in situ energetic particles. ApJ, 983(1), 33. (www)

  @article{ , abstract = {How impulsive solar energetic particle (SEP) events are produced by magnetic-reconnection-driven processes during solar flares remains an outstanding question. Here we report a short-duration SEP event associated with an X-class eruptive flare on 2021 July 3, using a combination of remote sensing observations and in situ measurements. The in situ SEPs were recorded by multiple spacecraft including the Parker Solar Probe. The hard X-ray (HXR) light curve exhibits two impulsive periods. The first period is characterized by a single peak with a rapid rise and decay, while the second period features a more gradual HXR light curve with a harder spectrum. Such observation is consistent with in situ measurements: the energetic electrons were first released during the early impulsive phase when the eruption was initiated. The more energetic in situ electrons were released several minutes later during the second period of the impulsive phase when the eruption was well underway. This second period of energetic electron acceleration also coincides with the release of in situ energetic protons and the onset of an interplanetary type III radio burst. We conclude that these multimessenger observations favor a two-phase particle acceleration scenario: the first, less energetic electron population was produced during the initial reconnection that triggers the flare eruption, and the second, more energetic electron population was accelerated in the region above the loop-top below a well-developed, large-scale reconnection current sheet induced by the eruption.}, archive = {J_ApJ}, author = {Meiqi Wang and Bin Chen and Trevor Knuth and Christina Cohen and Jeongwoo Lee and Haimin Wang and Sijie Yu}, doi = {10.3847/1538-4357/adbdd0}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {33}, shortjournal = {The Astrophys. J.}, title = {Two phases of particle acceleration of a solar flare associated with in situ energetic particles}, volume = {983}, year = {2025}, }
• (2025). Anisotropic velocity fluctuations in galaxy mergers: A probe of the magnetic field. ApJ, 983(1), 32. (www)

  @article{ , abstract = {Magnetic fields and turbulence are fundamental to the evolutions of galaxies, yet their precise measurement and analysis present significant challenges. The recently developed Velocity Gradient Technique (VGT), which capitalizes on the anisotropy inherent in magnetohydrodynamic (MHD) turbulence, represents a new method for mapping magnetic fields in galaxies using spectroscopic observations. Most validations of VGT thus far have relied upon idealized MHD turbulence simulations, however, which lack the more complex dynamics found in galaxies and galaxy mergers. In this study, we scrutinize VGT using an AREPO-based cosmological galaxy merger simulation, testing its effectiveness across pre-merger, merging, and post-merger stages. We examine the underlying assumptions of VGT and probe the statistics of gas density, velocity, and magnetic fields over time. We find that the velocity fluctuations are indeed anisotropic at each stage, being larger in the direction perpendicular to the local magnetic field, as required by VGT. We find additionally that galaxy mergers substantially intensify the velocity and density fluctuations and amplify the magnetic fields at all scales. The observed scaling of the velocity fluctuations shows a steeper trend than r 1/2 between 0.6 and 3 kpc and a shallower trend at larger scales. The scaling of the magnetic field and density fluctuations at scales ≲1.0 kpc also predominantly aligns with r 1/2 . Finally, we compare results from VGT to those derived from polarization-like mock magnetic field measurements, finding consistent and statistically significant global agreement in all cases.}, archive = {J_ApJ}, author = {Yue Hu and Joseph Whittingham and Alex Lazarian and Christoph Pfrommer and Siyao Xu and Thomas Berlok}, doi = {10.3847/1538-4357/adbe68}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {32}, shortjournal = {The Astrophys. J.}, title = {Anisotropic velocity fluctuations in galaxy mergers: A probe of the magnetic field}, volume = {983}, year = {2025}, }
• (2025). The distance of quasar outflows from the central source: The first consistent values from emission and absorption determinations. ApJ, 983(1), 31. (www)

  @article{ , abstract = {Measuring the distance of quasar outflows from the central source ( R ) is essential for determining their importance for active galactic nucleus feedback. There are two methods to measure R : (1) a direct determination using spatially resolved integral field spectroscopy (IFS) of the outflow in emission and (2) an indirect method that uses the absorption troughs from ionic excited states. The column density ratio between the excited and resonance states yields the outflow number density. Combined with a knowledge of the outflow's ionization parameter, R can be determined. Generally, the IFS method probes an R range of several kiloparsecs or more, while the absorption method usually yields R values of less than 1 kpc. There is no inconsistency between the two methods as the determinations come from different objects. Here we report the results of applying both methods to the same quasar outflow, where we derive consistent determinations of R ≈ 5 kpc. This is the first time that the indirect absorption R determination is verified by a direct spatially resolved IFS observation. In addition, the velocities (and energetics) from the IFS and absorption data are found to be consistent. Therefore, these are two manifestations of the same outflow. In this paper we concentrate on the absorption R determination for the outflow seen in quasar 3C 191 using Very Large Telescope/X-shooter observations. We also reanalyze an older absorption determination for the outflow based on Keck/High Resolution Echelle Spectrometer data and find the revised measurement to be consistent with ours. Our companion paper details the IFS analysis of the same object.}, archive = {J_ApJ}, author = {Mayank Sharma and Nahum Arav and Qinyuan Zhao and Maryam Dehghanian and Doyee Byun and Gwen Walker and Luming Sun and Lu Shen and Yulong Gao and Guilin Liu and Junfeng Wang}, doi = {10.3847/1538-4357/adb9e1}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {31}, shortjournal = {The Astrophys. J.}, title = {The distance of quasar outflows from the central source: The first consistent values from emission and absorption determinations}, volume = {983}, year = {2025}, }
• (2025). EPOCHS. i. the discovery and star-forming properties of galaxies in the epoch of reionization at 6.5 < z < 18 with PEARLS and public JWST data. ApJ, 983(1), 30. (www)

  @article{ , abstract = {We present in this paper the discovery, properties, and a catalog of 1165 high-redshift 6.5 < z < 18 galaxies found in deep JWST NIRCam imaging from the GTO PEARLS survey combined with data from JWST public fields. We describe our bespoke homogeneous reduction process and our analysis of these areas including the NEP, CEERS, GLASS, NGDEEP, JADES, and ERO SMACS-0723 fields with over 214 arcmin 2 imaged to depths of ∼30 mag. We describe our rigorous methods for identifying these galaxies, involving the use of Lyman-break strength, detection significance criteria, visual inspection, and integrated photometric redshift probability distributions predominately at high redshift. Our sample is a robust and highly pure collection of distant galaxies from which we also remove brown dwarf stars, and calculate completeness and contamination from simulations. We include a summary of the basic properties of these z > 6.5 galaxies, including their redshift distributions, UV absolute magnitudes, and star formation rates. Our study of these young galaxies reveals a wide range of stellar population properties as seen in their colors and SED fits, which we compare to stellar population models, indicating a range of star formation histories (SFHs), dust, active galactic nuceli, and/or nebular emission. We find that a strong trend exists between stellar mass and ( U − V ) color, as well as the existence of the "main-sequence" of star formation for galaxies as early as z ∼ 12. This indicates that stellar mass, or an underlying variable correlating with stellar mass, is driving galaxy formation, in agreement with simulation predictions. We also discover ultra-high-redshift candidates at z > 12 in our sample and describe their properties. Finally, we note a significant observed excess of galaxies compared to models at z > 12, revealing a tension between predictions and our observations.}, archive = {J_ApJ}, author = {Christopher J. Conselice and Nathan Adams and Thomas Harvey and Duncan Austin and Leonardo Ferreira and Katherine Ormerod and Qiao Duan and James Trussler and Qiong Li and Ignas Juodžbalis and Lewi Westcott and Honor Harris and Louise T. C. Seeyave and Asa F. L. Bluck and Rogier A. Windhorst and Rachana Bhatawdekar and Dan Coe and Seth H. Cohen and Cheng Cheng and Simon P. Driver and Brenda Frye and Lukas J. Furtak and Norman A. Grogin and Nimish P. Hathi and Benne W. Holwerda and Rolf A. Jansen and Anton M. Koekemoer and Madeline A. Marshall and Mario Nonino and Aaron Robotham and Jake Summers and Stephen M. Wilkins and Christopher N. A. Willmer and Haojing Yan and Adi Zitrin}, doi = {10.3847/1538-4357/ada608}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {30}, shortjournal = {The Astrophys. J.}, title = {EPOCHS. i. the discovery and star-forming properties of galaxies in the epoch of reionization at 6.5 < z < 18 with PEARLS and public JWST data}, volume = {983}, year = {2025}, }
• (2025). Eight years of light from ASASSN-15oi: Toward understanding the late-time evolution of TDEs. ApJ, 983(1), 29. (www)

  @article{ , abstract = {We present results from an extensive follow-up campaign of the tidal disruption event (TDE) ASASSN-15oi spanning δt ∼ 10–3000 days, offering an unprecedented window into the multiwavelength properties of a TDE during its first ≈8 yr of evolution. ASASSN-15oi is one of the few TDEs with strong detections at X-ray, optical/UV, and radio wavelengths and it also featured two delayed radio flares at δt ∼ 180 days and δt ∼ 1400 days. Our observations at δt > 1400 days reveal an absence of thermal X-rays, a late-time variability in the nonthermal X-ray emission, and sharp declines in the nonthermal X-ray and radio emission at δt ∼ 2800 days and ∼3000 days, respectively. The UV emission shows no significant evolution at δt > 400 days and remains above the pre-TDE level. We show that a cooling envelope model can explain the thermal emission consistently across all epochs. We also find that a scenario involving episodic ejection of material due to stream–stream collisions can possibly explain the first radio flare. Given the peculiar spectral and temporal evolution of the late-time emission, however, constraining the origins of the second radio flare and the nonthermal X-rays remains challenging. Our study underscores the critical role of long-term, multiwavelength follow-up to fully characterize the extended evolutionary phases of a TDE.}, archive = {J_ApJ}, author = {A. Hajela and K. D. Alexander and R. Margutti and R. Chornock and M. Bietenholz and C. T. Christy and M. Stroh and G. Terreran and R. Saxton and S. Komossa and J. S. Bright and E. Ramirez-Ruiz and D. L. Coppejans and J. K. Leung and Y. Cendes and E. Wiston and T. Laskar and A. Horesh and G. Schroeder and Nayana A. J. and M. H. Wieringa and N. Velez and E. Berger and P. K. Blanchard and T. Eftekhari and S. Gomez and M. Nicholl and H. Sears and B. A. Zauderer}, doi = {10.3847/1538-4357/adb620}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {29}, shortjournal = {The Astrophys. J.}, title = {Eight years of light from ASASSN-15oi: Toward understanding the late-time evolution of TDEs}, volume = {983}, year = {2025}, }
• (2025). AT 2020nov: Evidence for disk reprocessing in a rare tidal disruption event. ApJ, 983(1), 28. (www)

  @article{ , abstract = {We present a detailed analysis of AT 2020nov, a tidal disruption event (TDE) in the center of its host galaxy, located at a redshift of z = 0.083. AT 2020nov exhibits unique features, including double-peaked Balmer emission lines, a broad UV/optical flare, and a peak log luminosity in the extreme-ultraviolet (EUV) estimated at \sim 45.6{6}_{-0.33}^{+0.10}\,{\rm{erg}}\,{{\rm{s}}}^{-1} . A late-time X-ray flare was also observed, reaching an absorbed luminosity of 1.67 × 10 43 erg s −1 approximately 300 days after the UV/optical peak. Multiwavelength coverage, spanning optical, UV, X-ray, and mid-infrared (MIR) bands, reveals a complex spectral energy distribution (SED) that includes MIR flaring indicative of dust echoes, suggesting a dust covering fraction consistent with typical TDEs. Spectral modeling indicates the presence of an extended, quiescent disk around the central supermassive black hole with a radius of \sim 5.0{6}_{-0.77}^{+0.59}\times 1{0}^{4}\,{R}_{{\rm{g}}} . The multicomponent SED model, which includes a significant EUV component, suggests that the primary emission from the TDE is reprocessed by this extended disk, producing the observed optical and MIR features. The lack of strong active galactic nuclei signatures in the host galaxy, combined with the quiescent disk structure, highlights AT 2020nov as a rare example of a TDE occurring in a galaxy with a dormant but extended preexisting accretion structure.}, archive = {J_ApJ}, author = {Nicholas Earl and K. Decker French and Enrico Ramirez-Ruiz and Katie Auchettl and Sandra I. Raimundo and Kyle W. Davis and Megan Masterson and Iair Arcavi and Wenbin Lu and Vivienne F. Baldassare and David A. Coulter and Thomas de Boer and Maria R. Drout and Hannah Dykaar and Ryan J. Foley and Christa Gall and Hua Gao and Mark E. Huber and David O. Jones and Danial Langeroodi and Chien-Cheng Lin and Eugene A. Magnier and Brenna Mockler and Margaret Shepherd and Margaret E. Verrico}, doi = {10.3847/1538-4357/adb974}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {28}, shortjournal = {The Astrophys. J.}, title = {AT 2020nov: Evidence for disk reprocessing in a rare tidal disruption event}, volume = {983}, year = {2025}, }
• (2025). A tale of two black holes: Multiband gravitational-wave measurement of recoil kicks. ApJ, 983(1), 27. (www)

  @article{ , abstract = {The nonlinear dynamics of General Relativity leave their imprint on remnants of black hole mergers in the form of a recoil "kick." The kick has profound astrophysical implications across the black hole mass spectrum, from stellar-mass to supermassive black holes. However, a direct measurement of the kick would require observing the binary from different orientations. Therefore, the kick is primarily inferred by constraining the premerger parameters, mainly the spin orientations and mass ratio of the black holes and fitting them with postmerger parameters. In this study, we demonstrate the prospects for such measurements of black hole kicks in a multiband gravitational-wave network consisting of space mission LISA, the current Earth-based detector network, and a third-generation detector. For two distinct cases of remnant black hole kick (68, 1006 km s −1 ) emerging from near identical premerger configuration of GW190521—the first confirmed intermediate-mass black hole—we find that the multiband network will recover with a 90% credible level of the projection of the kick vector relative to the orbital plane within tens of km s −1 accuracy. Such precise measurement of the kick offers a new set of multimessenger follow-ups and unprecedented tests of astrophysical formation channels.}, archive = {J_ApJ}, author = {Shobhit Ranjan and Karan Jani and Alexander H. Nitz and Kelly Holley-Bockelmann and Curt Cutler}, doi = {10.3847/1538-4357/adba4e}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {27}, shortjournal = {The Astrophys. J.}, title = {A tale of two black holes: Multiband gravitational-wave measurement of recoil kicks}, volume = {983}, year = {2025}, }
• (2025). A [C ii] 158 μm survey of damped lyα absorber galaxies at z ∼ 4: Observations of dense and metal-enriched neutral gas within the circumgalactic medium of star-forming galaxies. ApJ, 983(1), 26. (www)

  @article{ , abstract = {We present a survey undertaken with the Atacama Large Millimeter/submillimeter Array (ALMA) to study the galaxies associated with a representative sample of 16 damped Ly α absorbers (DLAs) at z ≈ 4.1–4.5, using the [C ii ] 158 μ m ([C ii ]) line. We detect seven [C ii ]-emitting galaxies in the fields of five DLAs, all of which have absorption metallicity [M/H] > −1.5. We find that the detectability of these H i -selected galaxies with ALMA is a strong function of DLA metallicity, with a detection rate of 7{1}_{-20}^{+11} % for DLAs with [M/H] > −1.5 and 0 +18 % for DLAs with [M/H] < −1.5. The identified DLA galaxies have far-IR properties similar to those of typical star-forming galaxies at z ∼ 4, with estimated obscured star formation rates ranging from ≲6 M ⊙ yr −1 to 110 M ⊙ yr −1 . High-metallicity DLAs therefore provide an efficient way to identify and study samples of high-redshift, star-forming galaxies, without preselecting the galaxies by their emission properties. The agreement between the velocities of the metal absorption lines of the DLA and the [C ii ] emission line of the DLA galaxy indicates that the metals within the DLA originated in the galaxy. With observed impact parameters between 14 and 59 kpc, this indicates that star-forming galaxies at z ∼ 4 have a substantial reservoir of dense, cold, neutral gas within their circumgalactic medium that has been enriched with metals from the galaxy.}, archive = {J_ApJ}, author = {Marcel Neeleman and Nissim Kanekar and J. Xavier Prochaska and Marc A. Rafelski and Lordrick A. Kahinga}, doi = {10.3847/1538-4357/adbbd1}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {26}, shortjournal = {The Astrophys. J.}, title = {A [C ii] 158 μm survey of damped lyα absorber galaxies at z ∼ 4: Observations of dense and metal-enriched neutral gas within the circumgalactic medium of star-forming galaxies}, volume = {983}, year = {2025}, }
• (2025). Reprocessing from highly ionized gas in the soft spectral state of v4641 sgr with NuSTAR. ApJ, 983(1), 25. (www)

  @article{ , abstract = {V4641 Sgr is a low-mass black hole X-ray binary system with somewhat puzzling spectral characteristics during its soft state. Recent high-resolution spectroscopic studies of V4641 Sgr have revealed strong ionized emission-line features in both the optical and X-ray bands, including P-Cygni signatures, and an unusually low soft-state luminosity, indicating that the central engine is obscured. Here, we present an analysis of five Nuclear Spectroscopic Telescope Array (NuSTAR) observations of V4641 Sgr taken during its recent outburst in 2021, when the source was in the soft state. We identify highly ionized Fe K emission lines—consistent with a combination of the near-neutral 6.4 keV Fe K α line and the H-like and He-like Fe K α and Fe K β transitions found at 6.7–7 keV and ∼8 keV—and find no evidence for strong relativistic broadening. The line fluxes correlate linearly with the observed disk continuum flux, implying a direct connection between the central engine and the reprocessing region. Most interestingly, all five spectra also show a persistent highly ionized Fe K continuum edge feature at ∼9 keV with a stable optical depth, which is likely smeared, implying a localized reprocessing zone. We find tentative supporting evidence for obscuration of the inner accretion disk based on its unusually low intrinsic luminosity, although the NuSTAR spectra do not require obscuration from cold, optically thick gas.}, archive = {J_ApJ}, author = {Riley M. T. Connors and Joey Neilsen and Aarran W. Shaw and James F. Steiner and Federico Vincentelli and Javier A. García and Phil Uttley and Ronald A. Remillard and Guglielmo Mastroserio}, doi = {10.3847/1538-4357/adbbdb}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {25}, shortjournal = {The Astrophys. J.}, title = {Reprocessing from highly ionized gas in the soft spectral state of v4641 sgr with NuSTAR}, volume = {983}, year = {2025}, }
• (2025). Is the central compact object in HESS j1731-347 a hybrid star with a quark core? an analysis with the constant speed of sound parameterization. ApJ, 983(1), 24. (www)

  @article{ , abstract = {In this work, we investigate the possibility of the compact object in HESS J1731-347 with M=0.7{7}_{-0.17}^{+0.20}{M}_{\odot } and R=10.{4}_{-0.78}^{+0.86}\,\mathrm{km} to be a hybrid star with quark matter in the inner core. The observation of this low-mass compact star dictates the use of a softer equation of state, which, on the contrary, cannot explain the massive compact stars. This poses a new challenge for astrophysicists in their search for the equation of state of compact objects. The hybrid equations of state are constructed using the IUFSU parameterization based on the relativistic mean field theory for the hadronic part and the generic constant speed of sound (CSS) parameterization for the phase transition to quark matter. The CSS framework is characterized by three key parameters, namely the transition density ( ρ tr ), the energy jumps (Δ ε ), and the speed of sound ( C s ). Here, our primary aim is to investigate the influence of individual CSS parameters on the formation of an object of small mass and radius compatible with HESS J1731-347 parameters. We have also examined the effect of hadronic parameters such as effective mass, symmetry energy, and the slope of the symmetry energy at saturation densities on the formation of this compact object. Finally, our analysis suggests that, within a 1 σ credible level, HESS J1731-347 aligns with the scenario of a stable hybrid star with early deconfinement and higher energy gap.}, archive = {J_ApJ}, author = {Suman Pal and Soumen Podder and Gargi Chaudhuri}, doi = {10.3847/1538-4357/adbc6b}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {24}, shortjournal = {The Astrophys. J.}, title = {Is the central compact object in HESS j1731-347 a hybrid star with a quark core? an analysis with the constant speed of sound parameterization}, volume = {983}, year = {2025}, }
• (2025). Spectral analysis of the X-ray flares in the 2023 outburst of the new black binary transient swift j1727.8–1613 observed with insight-HXMT. ApJ, 983(1), 23. (www)

  @article{ , abstract = {The new black hole transient Swift J1727.8–1613 exhibited a series of X-ray flares during its 2023 outburst extensively observed with Insight-HXMT. We analyze the spectra of the flaring period using a series of models consisting of a multicolor disk and several different nonthermal components, and several consistent conclusions are obtained among these models. First, Swift J1727.8–1613 was in the transition process from the hard intermediate state to the very high state (VHS) during the first flaring period (MJD 60197–60204), and afterward, it exhibited typical VHS parameter characteristics, such as the high temperature of the disk inner radius and a steep power-law spectrum with a photon index of 2.6. Second, the flares in the VHS are characterized by a rapid increase in the flux of the accretion disk, accompanied by a simultaneous rapid expansion of the inner radius, which could be apparent if the accretion disk hardening factor varies significantly. The strong power-law component during the VHS is likely produced by the synchrotron self-Compton process in the relativistic jets, which is in agreement with the observed weak reflection component and lack of correlation with the disk component.}, archive = {J_ApJ}, author = {Jia-Ying Cao and Jin-Yuan Liao and Shuang-Nan Zhang and Hua Feng and Jin-Lu Qu and Liang Zhang and He-Xin Liu and Wei Yu and Qing-Chang Zhao and Jing-Qiang Peng and Ming-Yu Ge and Lian Tao and Yan-Jun Xu and Shu Zhang and Zi-Xu Yang}, doi = {10.3847/1538-4357/adbd0f}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {23}, shortjournal = {The Astrophys. J.}, title = {Spectral analysis of the X-ray flares in the 2023 outburst of the new black binary transient swift j1727.8–1613 observed with insight-HXMT}, volume = {983}, year = {2025}, }
• (2025). Detection of molecular clouds in the PeVatron candidate source LHAASO j0341+5258 by the nobeyama 45-m radio telescope. ApJ, 983(1), 22. (www)

  @article{ , abstract = {We report a new CO observation survey of LHAASO J0341+5258, using the Nobeyama Radio Observatory 45-m telescope. LHAASO J0341+5258 is one of the unidentified ultra-high-energy (UHE; E > 100 TeV) gamma-ray sources detected by LHAASO. Our CO observations were conducted in 2024 February and March, with a total observation time of 36 hr, covering the LHAASO source (∼0 \mathop{.}\limits^{\unicode{x000b0}} 3–0 \mathop{.}\limits^{\unicode{x000b0}} 5 in radius) and its surrounding area (1° × 1 \mathop{.}\limits^{\unicode{x000b0}} 5). Within the LHAASO source extent, we identified five compact (<2 pc) molecular clouds at nearby distances (<1–4 kpc). These clouds can serve as proton–proton collision targets, producing hadronic gamma rays via neutral pion decays. Based on the hydrogen densities (700–5000 cm −3 ) estimated from our CO observations and archived H i data from the Dominion Radio Astrophysical Observatory survey, we derive the total proton energy of W p ( E > 1 TeV) ∼ 10 45 erg to account for the gamma-ray flux. One of the molecular clouds appears to be likely associated with an asymptotic giant branch (AGB) star with an extended CO tail, which may indicate some particle acceleration activities. However, the estimated maximum particle energy below 100 TeV makes the AGB-like star unlikely to be a PeVatron site. We conclude that the UHE emission observed in LHAASO J0341+5258 could be due to hadronic interactions between the newly discovered molecular clouds and TeV–PeV protons originating from a distant SNR or due to leptonic emission from a pulsar wind nebula candidate, which is reported in our companion X-ray observation paper.}, archive = {J_ApJ}, author = {Naomi Tsuji and Shunya Takekawa and Kaya Mori and Alison Mitchell and Shuo Zhang and Priyadarshini Bangale and Stephen DiKerby and Tülün Ergin and Jooyun Woo and Samar Safi-Harb and Shinta Kasuya}, doi = {10.3847/1538-4357/adb7df}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {22}, shortjournal = {The Astrophys. J.}, title = {Detection of molecular clouds in the PeVatron candidate source LHAASO j0341+5258 by the nobeyama 45-m radio telescope}, volume = {983}, year = {2025}, }
• (2025). Discovery of a pulsar wind nebula candidate associated with the galactic PeVatron 1LHAASO j0343+5254u. ApJ, 983(1), 21. (www)

  @article{ , abstract = {The astronomical origins of the most energetic galactic cosmic rays and gamma rays are still uncertain. X-ray follow-up of candidate "PeVatrons"—systems producing cosmic rays with energies exceeding 1 PeV—can constrain their spatial origin, identify likely counterparts, and test particle emission models. Using ∼120 ks of XMM-Newton observations, we report the discovery of a candidate pulsar wind nebula, a possible counterpart for the LHAASO PeVatron J0343+5254u. This extended source has a power-law X-ray spectrum with spectral index Γ X = 1.9—softer at greater distance from the center—and asymmetric spatial extension out to \approx 2^{\prime} . We conduct leptonic modeling of the X-ray and gamma-ray radiation from this complex system, showing that a fully leptonic model with elevated IR photon fields can explain the multiwavelength emission from this source, similar to other very high-energy pulsar wind nebulas; excess gamma-ray emissivity not explained by a leptonic model may be due to hadronic interactions in nearby molecular cloud regions, which might also produce detectable astroparticle flux.}, archive = {J_ApJ}, author = {Stephen DiKerby and Shuo Zhang and Tülün Ergin and Naomi Tsuji and Kaya Mori and Fabio Acero and Samar Safi-Harb and Shunya Takekawa and Jooyun Woo}, doi = {10.3847/1538-4357/adb7e0}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {21}, shortjournal = {The Astrophys. J.}, title = {Discovery of a pulsar wind nebula candidate associated with the galactic PeVatron 1LHAASO j0343+5254u}, volume = {983}, year = {2025}, }
• (2025). The JWST-NIRCam view of sagittarius c. II. evidence for magnetically dominated h ii regions in the central molecular zone. ApJ, 983(1), 20. (www)

  @article{ , abstract = {We present JWST-NIRCam narrowband, 4.05 μ m Br α images of the Sgr C H ii region, located in the central molecular zone (CMZ) of the Galaxy. Unlike any H ii region in the solar vicinity, the Sgr C plasma is dominated by filamentary structure in both Br α and the radio continuum. Some bright filaments, which form a fractured arc with a radius of about 1.85 pc centered on the Sgr C star-forming molecular clump, likely trace ionization fronts. The brightest filaments form a " π -shaped" structure in the center of the H ii region. Fainter filaments radiate away from the surface of the Sgr C molecular cloud. The filaments are emitting optically thin free–free emission, as revealed by spectral index measurements from 1.28 GHz (MeerKAT) to 97 GHz (Atacama Large Millimeter/submillimeter Array). But, the negative in-band 1 to 2 GHz spectral index in the MeerKAT data alone reveals the presence of a nonthermal component across the entire Sgr C H ii region. We argue that the plasma flow in Sgr C is controlled by magnetic fields, which confine the plasma to ropelike filaments or sheets. This results in the measured nonthermal component of low-frequency radio emission plasma, as well as a plasma β (thermal pressure divided by magnetic pressure) below 1, even in the densest regions. We speculate that all mature H ii regions in the CMZ, and galactic nuclei in general, evolve in a magnetically dominated, low plasma β regime.}, archive = {J_ApJ}, author = {John Bally and Samuel Crowe and Rubén Fedriani and Adam Ginsburg and Rainer Schödel and Morten Andersen and Jonathan C. Tan and Zhi-Yun Li and Francisco Nogueras-Lara and Yu Cheng and Chi-Yan Law and Q. Daniel Wang and Yichen Zhang and Suinan Zhang}, doi = {10.3847/1538-4357/ad9d0b}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {20}, shortjournal = {The Astrophys. J.}, title = {The JWST-NIRCam view of sagittarius c. II. evidence for magnetically dominated h ii regions in the central molecular zone}, volume = {983}, year = {2025}, }
• (2025). The JWST-NIRCam view of sagittarius c. i. massive star formation and protostellar outflows. ApJ, 983(1), 19. (www)

  @article{ , abstract = {We present James Webb Space Telescope (JWST) Near Infrared Camera observations of the massive star-forming molecular cloud Sagittarius C (Sgr C) in the Central Molecular Zone (CMZ). In conjunction with ancillary mid-IR and far-IR data, we characterize the two most massive protostars in Sgr C via spectral energy distribution (SED) fitting, estimating that they each have current masses of m * ∼ 20 M ⊙ and surrounding envelope masses of ∼100 M ⊙ . We report a census of lower-mass protostars in Sgr C via a search for infrared counterparts to millimeter continuum dust cores found with the Atacama Large Millimeter/submillimeter Array (ALMA). We identify 88 molecular hydrogen outflow knot candidates originating from outflows from protostars in Sgr C, the first such unambiguous detections in the infrared in the CMZ. About a quarter of these are associated with flows from the two massive protostars in Sgr C; these extend for over 1 pc and are associated with outflows detected in ALMA SiO line data. An additional ∼40 features likely trace shocks in outflows powered by lower-mass protostars throughout the cloud. We report the discovery of a new star-forming region hosting two prominent bow shocks and several other line-emitting features driven by at least two protostars. We infer that one of these is forming a high-mass star given an SED-derived mass of m * ∼ 9 M ⊙ and associated massive (∼90 M ⊙ ) millimeter core and water maser. Finally, we identify a population of miscellaneous molecular hydrogen objects that do not appear to be associated with protostellar outflows.}, archive = {J_ApJ}, author = {Samuel Crowe and Rubén Fedriani and Jonathan C. Tan and Alva Kinman and Yichen Zhang and Morten Andersen and Lucía Bravo Ferres and Francisco Nogueras-Lara and Rainer Schödel and John Bally and Adam Ginsburg and Yu Cheng and Yao-Lun Yang and Sarah Kendrew and Chi-Yan Law and Joseph Armstrong and Zhi-Yun Li}, doi = {10.3847/1538-4357/ad8889}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {19}, shortjournal = {The Astrophys. J.}, title = {The JWST-NIRCam view of sagittarius c. i. massive star formation and protostellar outflows}, volume = {983}, year = {2025}, }
• (2025). The BoRG-JWST survey: Program overview and first confirmations of luminous reionization-era galaxies from pure-parallel observations. ApJ, 983(1), 18. (www)

  @article{ , abstract = {We present the BoRG-JWST survey, a combination of two JWST Cycle 1 programs aimed at obtaining NIRSpec spectroscopy of representative, UV-bright 7 < z < 10 galaxy candidates across 22 independent sight lines selected from Hubble/WFC3 pure-parallel observations. We confirm the high- z nature of 12 out of 21 observed primary targets through low-resolution prism observations, with the rest revealing themselves unsurprisingly to be z ∼ 1–3 interlopers, brown dwarfs, or yielding inconclusive results. From the Multi Shutter Array (MSA) observations, we confirm an additional nine filler sources at z > 5, highlighting the large abundance of high-redshift galaxies even in individual WFC3 pointings. The primary sample spans the absolute magnitude range −20.4 mag < M UV < −22.4 mag and harbors UV continuum slopes of β ≃ −2.5 to −2.0, representing some of the most luminous z > 7 sources currently known and comparable to the brightest NIRCam sources at z > 10. Prominent [O iii ]+H β lines are found across the full sample, while a stack of sources reveals a plethora of other rest-optical lines and additional rest-UV C III ] 1909 Å emission. Despite their luminosities, none of the low-resolution spectra display evidence for type 1 active galactic nucleus activity based on a search for broad-line emission. Lastly, we present a spectroscopic data release of 188 confirmed 0.5 ≲ z ≲ 5.0 sources from filler MSA observations, highlighting the legacy value of the survey and a representative benchmark for comparisons to deep field observations.}, archive = {J_ApJ}, author = {Guido Roberts-Borsani and Micaela Bagley and Sofía Rojas-Ruiz and Tommaso Treu and Takahiro Morishita and Steven L. Finkelstein and Michele Trenti and Pablo Arrabal Haro and Eduardo Bañados and Óscar A. Chávez Ortiz and Katherine Chworowsky and Taylor A. Hutchison and Rebecca L. Larson and Nicha Leethochawalit and Gene C. K. Leung and Charlotte Mason and Rachel S. Somerville and Massimo Stiavelli and L. Y. Aaron Yung and Susan A. Kassin and Christian Soto}, doi = {10.3847/1538-4357/adba60}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {18}, shortjournal = {The Astrophys. J.}, title = {The BoRG-JWST survey: Program overview and first confirmations of luminous reionization-era galaxies from pure-parallel observations}, volume = {983}, year = {2025}, }
• (2025). Constraining first-order phase transition inside neutron stars with application of bayesian techniques on PSR j0437–4715 NICER data. ApJ, 983(1), 17. (www)

  @article{ , abstract = {Understanding the existence of phases of exotic matter and phase transitions within the cores of neutron stars is crucial to advancing our knowledge of cold dense matter physics. Recent multimessenger observations, including gravitational waves from neutron star mergers and precise X-ray data from NASA's Neutron Star Interior Composition Explorer (NICER) mission, have significantly constrained the neutron star equation of state (EOS). This study investigates the effects of phase transitions in neutron stars, focusing on NICER's latest observation of PSR J0437−4715. We employ Bayesian inference techniques to evaluate the presence of first-order phase transitions using a piecewise polytropic EOS model. Our analysis incorporates data from multiple NICER sources to refine constraints on key phase transition parameters, including critical density and transition depth. We find that including data from PSR J0437−4715 improves the evidence of phase transitions and tightens the EOS constraints, especially at higher densities. However, Bayes factor analysis only indicates a slight preference for models without phase transitions, and the current observational precision is insufficient to draw definitive conclusions. In particular, this polytropic model identifies the critical phase transition mass of neutron stars as being close to 1.4 solar masses, which coincides with the approximate mass range of PSR J0437–4715. This work emphasizes the importance of precise measurements of PSR J0437−4715 for deepening our understanding of neutron star interiors and exploring potential new physics at extreme densities.}, archive = {J_ApJ}, author = {Chun Huang and Shashwat Sourav}, doi = {10.3847/1538-4357/adbb67}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {17}, shortjournal = {The Astrophys. J.}, title = {Constraining first-order phase transition inside neutron stars with application of bayesian techniques on PSR j0437–4715 NICER data}, volume = {983}, year = {2025}, }
• (2025). RAMBO. i. project introduction and first results with uGMRT. ApJ, 983(1), 16. (www)

  @article{ , abstract = {Magnetic hot stars can emit both coherent and incoherent nonthermal radio emission. Understanding the nature of these emissions and their connection to stellar rotation and magnetic field characteristics remains incomplete. The RAdio Magnetospheres of B and O stars (RAMBO) project aims to address this gap by systematically detecting and characterizing gyrosynchrotron and cyclotron maser radio emission in rapidly rotating magnetic hot stars. Using the upgraded Giant Metrewave Radio Telescope, we present the first detection of radio emission from HD 55522 at 650 MHz, confirming it as a new radio-bright magnetic hot star. This supports the predictions of the Centrifugal Breakout model, furthering its application in understanding particle acceleration mechanisms in centrifugal magnetospheres of hot stars. Additionally, we report nondetections for four other targets, improving sensitivity limits by a factor of a few compared to previous observations. These findings demonstrate the potential of RAMBO to uncover the complexities of radio emission in massive stars and highlight the need for broader, multiwavelength observations to probe magnetospheric physics comprehensively. The sensitivity of the Square Kilometre Array will enable significant advancements.}, archive = {J_ApJ}, author = {Z. Keszthelyi and K. Kurahara and Y. Iwata and Y. Fujii and H. Sakemi and K. Takahashi and S. Yoshiura}, doi = {10.3847/1538-4357/adbbba}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {16}, shortjournal = {The Astrophys. J.}, title = {RAMBO. i. project introduction and first results with uGMRT}, volume = {983}, year = {2025}, }
• (2025). Dust coagulation assisted by streaming instability in protoplanetary disks. ApJ, 983(1), 15. (www)

  @article{ , abstract = {The streaming instability is a promising mechanism for planetesimal formation. The instability can rapidly form dense clumps that collapse self-gravitationally, which is efficient for large dust grains with Stokes number of the order of 0.1. However, dust growth models predict that collisional fragmentation prevents dust grains from growing to such sizes. We perform local simulations of the streaming instability and measure characteristic collision velocities and collision rates of dust grains based on their trajectories in moderate clumping. The collision velocities are of the order of 0.1% of the sound speed or lower, implying that dust grains can overcome the fragmentation barrier via clumping. We also find that the collision rates are appreciably high regardless of the low collision velocities. Corresponding timescales are of the order of 10 Keplerian periods or shorter, suggesting that dust grains can overcome the drift barrier as well. This streaming-instability-assisted coagulation greatly relaxes the conditions for planetesimal formation as recently implied.}, archive = {J_ApJ}, author = {Ryosuke T. Tominaga and Hidekazu Tanaka}, doi = {10.3847/1538-4357/adbbca}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {15}, shortjournal = {The Astrophys. J.}, title = {Dust coagulation assisted by streaming instability in protoplanetary disks}, volume = {983}, year = {2025}, }
• (2025). The emerging class of double-faced white dwarfs. ApJ, 983(1), 14. (www)

  @article{ , abstract = {We report our findings on a spectroscopic survey of seven unresolved DA+DB binary white dwarf candidates. We have discovered extreme spectroscopic variations in one of these candidates, SDSS J084716.21+484220.40. Previous analysis failed to reproduce the optical spectrum using a single object with a homogeneous atmosphere. Our time-resolved spectroscopy reveals a double-faced white dwarf that switches between a DBA and DA spectral type over 6.5 or 8.9 hr due to varying surface abundances. We also provide time-series spectroscopy of the magnetic DBA, SDSS J085618.94+161103.6 (LB 8915), and confirm an inhomogeneous atmosphere. We employ an atmosphere model with hydrogen caps and a helium belt that yields excellent fits to our time-resolved spectra. We use the oblique rotator model to derive the system geometry for both targets. With the addition of these two objects, the emerging class of double-faced white dwarfs now consists of seven members. We summarize the properties of this new class of objects, and discuss how magnetism impacts the convective processes and leads to the formation of double-faced white dwarfs. We identify cooler versions of white dwarfs with inhomogeneous atmospheres among the cool magnetic DA white dwarf sample, where the H α line is shallower than expected based on pure hydrogen atmosphere models.}, archive = {J_ApJ}, author = {Adam Moss and Mukremin Kilic and Pierre Bergeron and Gracyn Jewett and Warren R. Brown}, doi = {10.3847/1538-4357/adbd3a}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {14}, shortjournal = {The Astrophys. J.}, title = {The emerging class of double-faced white dwarfs}, volume = {983}, year = {2025}, }
• (2025). Strong amplitude modulation of hard-band X-ray quasiperiodic oscillation with soft-band flux in RE j1034+396. ApJ, 983(1), 13. (www)

  @article{ , abstract = {The X-ray quasiperiodic oscillation (QPO) is a remarkable form of variability in systems of compact object accretion. RE J1034+396, harboring the most significant X-ray QPO in active galactic nuclei (AGNs), is the most noteworthy source for in-depth analysis of AGN X-ray QPO properties. A long-term evolution of its QPO has been observed over the course of the observations. However, the short-term variability of its QPO properties remains unexplored within each observation that has long good time intervals (GTIs). We collect 12 XMM-Newton observations of RE J1034+396 with GTIs longer than 60 ks from publicly available data and conduct a detailed wavelet analysis focusing on the short-time modulation of the QPO. The QPO signals are found to undergo amplitude modulation in both the soft and hard bands, with a typical timescale of 17 ks. The soft flux is significantly higher when the hard QPO is present. They are highly correlated, with an average cross-correlation function (CCF) peak coefficient of 0.61 and a lag of approximately 3 ks. This novel finding provides fresh insights into the potential connection between the components of the corona emitting soft and hard X-ray photons. The CCF lag between the soft flux and the hard QPO evolves across the observations, potentially sharing the same origin as the previously observed interconnected evolution between QPO frequency and time lag.}, archive = {J_ApJ}, author = {Ruisong Xia and Hao Liu and Yongquan Xue}, doi = {10.3847/1538-4357/adbe6a}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {13}, shortjournal = {The Astrophys. J.}, title = {Strong amplitude modulation of hard-band X-ray quasiperiodic oscillation with soft-band flux in RE j1034+396}, volume = {983}, year = {2025}, }
• (2025). Photon-likeness of hadron showers and impact of lorentz boosting. ApJ, 983(1), 12. (www)

  @article{ , abstract = {We examine the probability of proton-induced air showers at E > 10 EeV being misidentified as photon induced due to neutral pions receiving a major part of the primary energy in the first interaction, thereby enhancing the electromagnetic shower component by their π 0 → γγ decay. Using CORSIKA simulations, we demonstrate the relevance of this effect at EeV energies. However, the probability for such photon-like events drops down strongly at the highest energies due to the increasing probability of Lorentz-boosted π 0 's suffering hadronic interactions before decay. Different hadronic interaction models suggest that photon-like hadronic events may be observed at current ultra-high-energy cosmic-ray observatories. A quantitative comparison of the observed number of background events found in recent photon searches published by the Pierre Auger Collaboration suggests that the hypothesis of upward fluctuations in π 0 production alone is insufficient to explain the data. Detailed detector simulations will be needed to quantify the significance of these differences.}, archive = {J_ApJ}, author = {Jannis Pawlowsky and Karl-Heinz Kampert and Julian Rautenberg}, doi = {10.3847/1538-4357/adbe72}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {12}, shortjournal = {The Astrophys. J.}, title = {Photon-likeness of hadron showers and impact of lorentz boosting}, volume = {983}, year = {2025}, }
• (2025). RUBIES reveals a massive quiescent galaxy at z = 7.3. ApJ, 983(1), 11. (www)

  @article{ , abstract = {We report the spectroscopic discovery of a massive quiescent galaxy at z spec = 7.29 ± 0.01, just  ∼700 Myr after the big bang. RUBIES-UDS-QG-z7 was selected from public JWST/NIRCam and MIRI imaging from the PRIMER survey and observed with JWST/NIRSpec as part of RUBIES. The NIRSpec/PRISM spectrum reveals one of the strongest Balmer breaks observed thus far at z > 6, with no emission lines but tentative Balmer and Ca absorption features, as well as a Lyman break. Simultaneous modeling of the NIRSpec/PRISM spectrum and NIRCam and MIRI photometry (spanning 0.9–18 μ m) shows that the galaxy formed a stellar mass of log ({M}_{* }/{M}_{\odot })=10.2{3}_{-0.04}^{+0.04} before z ∼ 8 and ceased forming stars 50–100 Myr prior to the time of observation, resulting in \mathrm{log}({{\rm{sSFR/Gyr}}}^{-1})\lt -1 . We measure a small physical size of 20{9}_{-24}^{+33}\,{\rm{pc}} , which implies a high stellar-mass surface density within the effective radius of \mathrm{log}({{\rm{\Sigma }}}_{* ,{\rm{e}}}/{M}_{\odot }\,{{\rm{kpc}}}^{-2})=10.8{5}_{-0.12}^{+0.11} , comparable to the highest densities measured in quiescent galaxies at z ∼ 2–5. The 3D stellar-mass density profile of RUBIES-UDS-QG-z7 is remarkably similar to the central densities of local massive ellipticals, suggesting that at least some of their cores may have already been in place at z > 7. The discovery of RUBIES-UDS-QG-z7 has strong implications for galaxy formation models: the estimated number density of quiescent galaxies at z ∼ 7 is  >100 × larger than predicted from any model to date, indicating that quiescent galaxies have formed earlier than previously expected.}, archive = {J_ApJ}, author = {Andrea Weibel and Anna de Graaff and David J. Setton and Tim B. Miller and Pascal A. Oesch and Gabriel Brammer and Claudia D. P. Lagos and Katherine E. Whitaker and Christina C. Williams and Josephine F.W. Baggen and Rachel Bezanson and Leindert A. Boogaard and Nikko J. Cleri and Jenny E. Greene and Michaela Hirschmann and Raphael E. Hviding and Adarsh Kuruvanthodi and Ivo Labbé and Joel Leja and Michael V. Maseda and Jorryt Matthee and Ian McConachie and Rohan P. Naidu and Guido Roberts-Borsani and Daniel Schaerer and Katherine A. Suess and Francesco Valentino and Pieter van Dokkum and Bingjie Wang}, doi = {10.3847/1538-4357/adab7a}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {11}, shortjournal = {The Astrophys. J.}, title = {RUBIES reveals a massive quiescent galaxy at z = 7.3}, volume = {983}, year = {2025}, }
• (2025). The qz5 survey. i. how the h i mass density of the universe evolves with cosmic time. ApJ, 983(1), 10. (www)

  @article{ , abstract = {We report that the neutral hydrogen (H i ) mass density of the Universe ( ρ H i ) increases with cosmic time since z ∼ 5, peaks at z ∼ 3, and then decreases toward z ∼ 0. This is the first result of Qz5, our spectroscopic survey of 63 quasars at z ≳ 5 with VLT/X-SHOOTER and Keck/ESI aimed at characterizing intervening H i gas absorbers at z ∼ 5. The main feature of Qz5 is the high resolution ( R ∼ 7000–9000) of the spectra, which allows us to (1) accurately detect high column density H i gas absorbers in an increasingly neutral intergalactic medium at z ∼ 5 and (2) determine the reliability of previous ρ H i measurements derived with lower resolution spectroscopy. We find five intervening damped Ly α absorbers (DLAs) at z > 4.5, which corresponds to the lowest DLA incidence rate ( 0.03{4}_{0.02}^{0.05} ) at z ≳ 2. We also measure the lowest ρ H i at z ≳ 2 from our sample of DLAs and subDLAs, corresponding to ρ H i =0.5{6}_{0.31}^{0.82}\times 1{0}^{8}\,{M}_{\odot } Mpc −3 at z ∼ 5. Taking into account our measurements at z ∼ 5 and systematic biases in the DLA detection rate at lower spectral resolutions, we conclude that ρ H i doubles from z ∼ 5 to z ∼ 3. From these results emerges a qualitative agreement between how the cosmic densities of H i gas mass, molecular gas mass, and star formation rate build up with cosmic time.}, archive = {J_ApJ}, author = {Grecco A. Oyarzún and Marc Rafelski and Lise Christensen and Fiona Ozyurt and Regina A. Jorgenson and M. Neeleman and Michele Fumagalli and J. Xavier Prochaska and G. Worseck and M. E. Wisz and George D. Becker and Sebastián López}, doi = {10.3847/1538-4357/adb430}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {10}, shortjournal = {The Astrophys. J.}, title = {The qz5 survey. i. how the h i mass density of the universe evolves with cosmic time}, volume = {983}, year = {2025}, }
• (2025). Lorentz invariance violation from gamma-ray bursts. ApJ, 983(1), 9. (www)

  @article{ , abstract = {Lorentz invariance violation (LV) is examined through the time delay between high-energy and low-energy photons in gamma-ray bursts (GRBs). Previous studies determined the LV energy scale as E LV ≃ 3.60 × 10 17 GeV using Fermi Gamma-ray Space Telescope (FGST) data. This study updates the time-delay model and reaffirms these findings with new observations. High-energy photons from GRBs at GeV and TeV bands are analyzed, including the 99.3 GeV photon from GRB 221009A (FGST), the 1.07 TeV photon from GRB 190114C (MAGIC), and the 12.2 TeV photon from GRB 221009A (LHAASO). Our analysis, in conjunction with previous data, consistently shows that high-energy photons are emitted earlier than low-energy photons at the source. By evaluating 17 high-energy photons from 10 GRBs observed by FGST, MAGIC, and LHAASO, we estimate the LV energy scale to be E LV ≃ 3.00 × 10 17 GeV. The null hypothesis of dispersion-free vacuum E = pc (or, equivalently, the constant light speed v γ = c ) is rejected at a significance level of 3.1 σ or higher.}, archive = {J_ApJ}, author = {Hanlin Song and Bo-Qiang Ma}, doi = {10.3847/1538-4357/adb8d4}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {9}, shortjournal = {The Astrophys. J.}, title = {Lorentz invariance violation from gamma-ray bursts}, volume = {983}, year = {2025}, }
• (2025). Cosmology and astrophysics with the diffuse eRASS1 X-ray angular power spectrum. ApJ, 983(1), 8. (www)

  @article{ , abstract = {The recent tension in the value of the cosmological parameter {S}_{8}\equiv {\sigma }_{8}{({{\rm{\Omega }}}_{M}/0.3)}^{1/2} , which represents the amplitude of the matter density fluctuations of the Universe, has not been resolved. In this work, we present constraints on S 8 with the X-ray angular power spectra of clusters and groups measured with the half-sky map from eROSITA All Sky Survey Data Release 1 (eRASS1). Thanks to the extensive sky coverage of eRASS1, it achieves unprecedented precision compared to previous power spectrum measurements. Using a well-calibrated, physical halo gas model that includes astrophysics of feedback and nonthermal pressure support, we obtain {S}_{8}=0.8{0}_{-0.01}^{+0.02} with 1 σ uncertainty that is competitive against other cosmological probes. Our derived S 8 value is smaller than the primary cosmic microwave background measurements from Planck, but still consistent to within 1 σ . We also obtain constraints on the astrophysics of feedback, nonthermal pressure, equation of state in cluster cores, and gas boundaries in clusters and groups. We discuss how additional X-ray observations, and cosmological surveys in microwave and optical, will further improve the cosmological constraints with the angular power spectrum. Our work demonstrates that the angular power spectrum of clusters and groups is a promising probe of both cosmology and astrophysics.}, archive = {J_ApJ}, author = {Erwin T. Lau and Ákos Bogdán and Daisuke Nagai and Nico Cappelluti and Masato Shirasaki}, doi = {10.3847/1538-4357/adba5b}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {8}, shortjournal = {The Astrophys. J.}, title = {Cosmology and astrophysics with the diffuse eRASS1 X-ray angular power spectrum}, volume = {983}, year = {2025}, }
• (2025). Limited hysteresis in the atmospheric dynamics of hot jupiters. ApJ, 983(1), 7. (www)

  @article{ , abstract = {Over the past two decades, a coherent picture has emerged of the atmospheric dynamics of hot Jupiters from a combination of three-dimensional general circulation models and astronomical observations. This paradigm consists of hot Jupiters being spin-synchronized due to their close-in orbit, with a resulting large day-to-night irradiation gradient driving a day-to-night temperature contrast. This day-to-night temperature contrast in turn raises day-to-night pressure gradients that are balanced by a circulation with wind speeds on the order of km s −1 . The dominant feature of this circulation is a super-rotating equatorial jet, maintained by eddy-mean flow interactions that pump momentum into the jet. In this work, I explore the dependence of this circulation paradigm on the initial thermal and dynamical conditions in atmospheric circulation models of hot Jupiters. To do so, I conduct MITgcm simulations of the atmospheric circulation of hot Jupiters with both varying initial wind directions and initial temperature profiles. I find that the results are insensitive to the initial conditions, implying that the current paradigm of hot-Jupiter circulation exhibits at most limited hysteresis. I demonstrate that there is a single characteristic wind speed of hot Jupiters for given planetary and atmospheric parameters using an idealized scaling theory, and discuss implications for the interpretation of hot Jupiter observations.}, archive = {J_ApJ}, author = {Thaddeus D. Komacek}, doi = {10.3847/1538-4357/adbae9}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {7}, shortjournal = {The Astrophys. J.}, title = {Limited hysteresis in the atmospheric dynamics of hot jupiters}, volume = {983}, year = {2025}, }
• (2025). A spectroastrometric study of the low-velocity wind from DG tau a*. ApJ, 983(1), 6. (www)

  @article{ , abstract = {We obtained high-spectral resolution spectra (Δ v ∼ 2.5 km s −1 ) for DG Tau A from 4800 Å to 7500 Å using Subaru High Dispersion Spectrograph for the first time. The low-velocity components (LVCs, ∣ v ∣ < 100 km s −1 ) were observed in the [O I ] 5577, 6300, 6364 Å, [S II ] 6716, 6731 Å lines. The offset position spectra observed in a component within the LVC velocity range between –16 km s −1 and –41 km s −1 , namely, LVC-M, show a "negative velocity gradient," supporting the presence of a wide-angled wind. With 12–70 au wind lengths measured using spectroastrometry, we estimate a lower limit to the wind mass-loss rate of ∼10 −8 M ⊙ yr −1 . In addition to the LVCs, we identify two high-velocity components (HVCs, ∣ v ∣ > 100 km s −1 ) associated with the collimated jet in 26 lines ([N I ], [N II ], [O I ], [O II ], [O III ], [S II ], [Ca II ], [Fe II ], H α , H β , He I ). The one with a clear spatial offset from the star ( n e ∼ 10 4 cm −3 , HVC1) is associated with an internal shock surface of the jet, while the other at the base ( n e ∼ 10 6 cm −3 , HVC2) may be a stationary shock component. We find that the observed line profiles and the spatial scales of the LVC emission do not agree with the existing predictions for photoevaporative or magnetohydrodynamical disk winds. These could be explained by the X-wind model, but synthetic observations are required for detailed comparisons.}, archive = {J_ApJ}, author = {Yu-Ru Chou and Michihiro Takami and Shin-Ping Lai and Emma Whelan and Noah B. Otten and Min Fang and Akito Tajitsu and Masaaki Otsuka and Hsien Shang and Chun-Fan Liu and Jennifer Karr and Aisling Murphy}, doi = {10.3847/1538-4357/adbbce}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {6}, shortjournal = {The Astrophys. J.}, title = {A spectroastrometric study of the low-velocity wind from DG tau a*}, volume = {983}, year = {2025}, }
• (2025). The structure of the local interstellar medium. VII. additional new mg ii, fe ii, and mn ii observations toward stars within 100 pc. ApJ, 983(1), 5. (www)

  @article{ , abstract = {We present new high-resolution ( R ∼ 114,000), near-ultraviolet spectra in the direction of 36 nearby (<100 pc) stars to uncover the structure and composition of the local interstellar medium (LISM). The spectra were obtained using the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope. We model the LISM absorption due to Mg ii , Fe ii , and Mn ii in order to measure new velocities, Doppler broadening parameters, and column densities for interstellar clouds; refine the extent of known clouds; and identify new clouds. Based on our analyses of these 36 new sight lines, we find one to four discrete LISM features for each individual sight line, with the number of components remaining relatively flat until increasing at  ≈60 pc. By comparing our final measurements with a dynamical model of the LISM by S. Redfield & J. L. Linsky, we determine that 77% of the predictions made by the kinematic model are confirmed by observed components in the new lines of sight and identify 10 LISM features among eight sight lines that do not match the model. In addition to testing and refining three-dimensional kinematic models of the LISM, the substantially increased number of integrated Mg ii emission fluxes presented here will be valuable for predicting the far-ultraviolet and extreme-ultraviolet emission for these stars. We also find that six stars in our sample show possible circumstellar disk absorption, including 47 UMa, for which a disk has not yet been confirmed.}, archive = {J_ApJ}, author = {Azmain H. Nisak and Seth Redfield and Jeffrey L. Linsky and Brian E. Wood and Allison Youngblood}, doi = {10.3847/1538-4357/adb960}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {5}, shortjournal = {The Astrophys. J.}, title = {The structure of the local interstellar medium. VII. additional new mg ii, fe ii, and mn ii observations toward stars within 100 pc}, volume = {983}, year = {2025}, }
• (2025). Proton intensity dropout in isotropic turbulence regime during gradual solar energetic particle events in solar cycle 23. ApJ, 983(1), 4. (www)

  @article{ , abstract = {When the Wind spacecraft started its only journey to Lagrange point L2 in 2003 October, it entered an isotropic turbulent environment with radially mean magnetic field ( B m ) and slow solar wind speed ( V SW ). On October 26, it detected a particle intensity dropout interval following a gradual solar energetic particle event. In addition, it recorded three magnetic field rotations corresponding to one-sided increases in V SW , indicating the occurrence of magnetic switchback in the Alfvénic solar wind. Since the last switchback interval is just before the dropout interval, we studied the difference of the pitch angle distribution (PAD) of protons between them. In the switchback interval ( B m perpendicular to V sw ), the PAD maximum is located at μ ∼ +1, where μ is the pitch angle cosine, while, in the dropout interval ( B m antiparallel to V sw ), the maximum is at μ ∼ 0. The difference indicates that protons with greater gyroradii cannot be confined in the curved magnetic field lines and can be injected into the dropout region with μ ∼ 0. Therefore, the analysis of proton pitch angle scattering in the dropout interval can be greatly simplified due to the short duration of the interval and the sharp initial conditions. Compared with the analytical solution of the Fokker–Planck equation, we deduce that the parallel mean free path of 2.1 MeV protons is 3.7 ± 0.5 au, which means that the dropout of proton intensity in the isotropic turbulent regime is also caused by insufficient spatial diffusion of protons.}, archive = {J_ApJ}, author = {Lun C. Tan}, doi = {10.3847/1538-4357/adba50}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {4}, shortjournal = {The Astrophys. J.}, title = {Proton intensity dropout in isotropic turbulence regime during gradual solar energetic particle events in solar cycle 23}, volume = {983}, year = {2025}, }
• (2025). Infant type ia supernovae from the KMTNet. i. multicolor evolution and populations. ApJ, 983(1), 3. (www)

  @article{ , abstract = {We conduct a systematic analysis of the early multiband light curves and colors of 19 Type Ia supernovae (SNe) from the Korea Microlensing Telescope Network SN Program, including 16 previously unpublished events. Seven are detected ≲1 day (as early as ≲1 hr) since the estimated epoch of first light and the rest ≲3 days. Some show excess emission within  <0.5 day to  ∼2 days, but most show pure power-law rises. Colors are initially diverse before  ∼5 days, but converge to similar values at  ∼10 days. We identify at least three populations based on 2–5 day color evolution: (1) "early-blues" exhibit slowly evolving colors consistent with a  ∼17,000 K blackbody; (2) "early-reds" have initially blue B − V and red V − i colors that cannot simultaneously be fit with a blackbody—likely due to suppression of B - and i -band flux by Fe ii / iii and Ca ii —and evolve more rapidly; and (3) "early-yellows" evolve blueward, consistent with thermal heating from ∼8000–13,000 K. Distributions of early-blue and early-red colors are compatible with them being either distinct populations—with early-reds comprising (60 ± 15)% of them—or extreme ends of one continuous population, whereas the early-yellow population identified here is clearly distinct. Compared to the other populations, early-blues in our sample differ by exhibiting excess emission within 1–2 days, nearly constant peak brightness regardless of Δ m 15 ( B ) after standardization, and shallower Si ii features. Early-blues also prefer star-forming host environments, while early-yellows and, to a lesser extent, early-reds prefer quiescent ones. These preferences appear to indicate at least two Type Ia SN production channels based on stellar population age, while early-reds and early-blues may still share a common origin.}, archive = {J_ApJ}, author = {Yuan Qi Ni and Dae-Sik Moon and Maria R. Drout and Youngdae Lee and Patrick Sandoval and Jeehye Shin and Hong Soo Park and Sang Chul Kim and Kyuseok Oh}, doi = {10.3847/1538-4357/adbbb7}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {3}, shortjournal = {The Astrophys. J.}, title = {Infant type ia supernovae from the KMTNet. i. multicolor evolution and populations}, volume = {983}, year = {2025}, }
• (2025). Citizen science identification of isolated blue stellar systems in the virgo cluster*. ApJ, 983(1), 2. (www)

  @article{ , abstract = {We present a catalog of 34 new candidate (13 high confidence) isolated, young stellar systems within the Virgo galaxy cluster identified through a citizen science search of public optical and ultraviolet imaging. "Blue blobs" are a class of blue, faint, isolated, extremely low stellar mass, and metal-rich star-forming clouds embedded in the hot intracluster medium of the Virgo cluster. Only six blue blobs were known previously and here we confirm an additional six of our candidates through velocity and metallicity measurements from follow-up optical spectroscopy on the Hobby–Eberly Telescope (HET). Our 13 high confidence candidates (including the six confirmed) have properties consistent with prior known blue blobs and are inconsistent with being low-mass galaxies. Most candidates are concentrated in relatively dense regions, roughly following filamentary structures within the cluster, but avoiding its center. Three of our candidates are likely the stellar counterparts of known "optically dark" clouds of neutral hydrogen in the cluster, while a further four are widely separated extensions to previously known blue blobs. The properties of our new candidates are consistent with previous conclusions that blue blobs likely originated from ram pressure stripping events, however, their locations in velocity–projected cluster-centric radius phase space imply that their parent galaxies are not on their first infall into the cluster. Through our ongoing follow-up program with HET we aim to confirm additional candidates, however, detailed understanding of the stellar populations and star formation histories of blue blobs will require JWST observations.}, archive = {J_ApJ}, author = {Swapnaneel Dey and Michael G. Jones and David J. Sand and Nicolas Mazziotti and Steven Janowiecki and Gregory R. Zeimann and Paul Bennet}, doi = {10.3847/1538-4357/adbbd8}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {2}, shortjournal = {The Astrophys. J.}, title = {Citizen science identification of isolated blue stellar systems in the virgo cluster*}, volume = {983}, year = {2025}, }
• (2025). Spatially resolved polarization variation of the crab nebula. ApJ, 983(1), 1. (www)

  @article{ , abstract = {We examined the spatially resolved polarization variations in the Crab Nebula over 2 yr, using observational data from the Imaging X-ray Polarimetry Explorer, and offer key insights into its magnetic field structures and evolution. The results show significant temporal changes in the polarization degree (PD) across three regions of interest in the 2–8 keV energy band. Regions (a) and (b), located in the northern and the southwestern parts of the study area, exhibit PD variations with significance levels greater than 4 σ and 3 σ , respectively. Region (c), located in the southwest, shows a notable decrease in PD with a significance greater than 5 σ . However, no significant variation in the polarization angle was observed. Meanwhile, notable flux variations were detected, likely influenced by dynamic processes such as magnetized turbulence within the nebula.}, archive = {J_ApJ}, author = {Chao Zuo and Fei Xie and Mingyu Ge and Wei Deng and Kuan Liu and Fabio La Monaca and Alessandro Di Marco and Wenhao Wei and Wei Chen}, doi = {10.3847/1538-4357/adbca0}, journal = {The Astrophysical Journal}, month = {4}, number = {1}, pages = {1}, shortjournal = {The Astrophys. J.}, title = {Spatially resolved polarization variation of the crab nebula}, volume = {983}, year = {2025}, }
• (2025). Erratum: “GRB progenitor classification from gamma-ray burst prompt and afterglow observations” (2024, ApJ, 974, 120). ApJ, 982(2), 208. (www)

  @article{ , archive = {J_ApJ}, author = {P. Nuessle and J. L. Racusin and N. E. White}, doi = {10.3847/1538-4357/adac62}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {208}, shortjournal = {The Astrophys. J.}, title = {Erratum: “GRB progenitor classification from gamma-ray burst prompt and afterglow observations” (2024, ApJ, 974, 120)}, volume = {982}, year = {2025}, }
• (2025). Erratum: “Multiepoch ultraviolet HST observations of accreting low-mass stars” (2019, ApJ, 874, 129). ApJ, 982(2), 207. (www)

  @article{ , archive = {J_ApJ}, author = {Connor E. Robinson and Catherine C. Espaillat}, doi = {10.3847/1538-4357/adb96c}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {207}, shortjournal = {The Astrophys. J.}, title = {Erratum: “Multiepoch ultraviolet HST observations of accreting low-mass stars” (2019, ApJ, 874, 129)}, volume = {982}, year = {2025}, }
• (2025). Erratum: “The impact of cosmic variance on inferences of global neutral fraction derived from lyα luminosity functions during reionization” (2023, ApJ, 953, 29). ApJ, 982(2), 206. (www)

  @article{ , archive = {J_ApJ}, author = {Sean Bruton and Claudia Scarlata and Francesco Haardt and Matthew J. Hayes and Charlotte Mason and Alexa M. Morales and Andrei Mesinger}, doi = {10.3847/1538-4357/adbaee}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {206}, shortjournal = {The Astrophys. J.}, title = {Erratum: “The impact of cosmic variance on inferences of global neutral fraction derived from lyα luminosity functions during reionization” (2023, ApJ, 953, 29)}, volume = {982}, year = {2025}, }
• (2025). Erratum: “Precise bolometric luminosities and effective temperatures of 23 late-T and y dwarfs obtained with JWST” (2024, ApJ, 973, 107). ApJ, 982(2), 205. (www)

  @article{ , archive = {J_ApJ}, author = {Samuel A. Beiler and Michael C. Cushing and J. Davy Kirkpatrick and Adam C. Schneider and Sagnick Mukherjee and Mark S. Marley and Federico Marocco and Richard L. Smart}, doi = {10.3847/1538-4357/adbd3b}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {205}, shortjournal = {The Astrophys. J.}, title = {Erratum: “Precise bolometric luminosities and effective temperatures of 23 late-T and y dwarfs obtained with JWST” (2024, ApJ, 973, 107)}, volume = {982}, year = {2025}, }
• (2025). Three-dimensional structure of incomplete Carbon–Oxygen detonations in type ia supernovae. ApJ, 982(2), 204. (www)

  @article{ , abstract = {Carbon–oxygen (CO) detonation with reactions terminating either after burning of 12 C in the leading 12 C + 12 C reaction or after burning of 12 C and 16 O to Si-group elements may occur in the low-density outer layers of exploding white dwarfs and be responsible for the production of intermediate-mass elements observed in the outer layers of Type Ia supernovae. Basic one-dimensional properties of CO-detonations have been summarized in our previous work. This paper presents the results of two- and three-dimensional numerical simulations of low-density CO-detonations and discusses their multidimensional stability, cellular structure, and propagation through a constant low-density background. We find three-dimensional CO detonations to be strikingly different from their one-dimensional and two-dimensional counterparts. Three-dimensional detonations are significantly more robust and capable of propagating without decay compared to highly unstable and marginal one- and two-dimensional detonations. The detonation cell size and whether burning of 12 C in a three-dimensional detonation wave is followed by the subsequent 16 O burning are sensitive to both the background density and the initial 12 C to 16 O mass ratio. We also discuss the possible implications for understanding the observed early-time bumps in light curves.}, archive = {J_ApJ}, author = {A. Khokhlov and I. Domínguez and A. Y. Chtchelkanova and P. Hoeflich and E. Baron and K. Krisciunas and M. Phillips and N. Suntzeff and L. Wang}, doi = {10.3847/1538-4357/adb0c1}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {204}, shortjournal = {The Astrophys. J.}, title = {Three-dimensional structure of incomplete Carbon–Oxygen detonations in type ia supernovae}, volume = {982}, year = {2025}, }
• (2025). The host galaxy of FRB 20190520B and its unique ionized gas distribution. ApJ, 982(2), 203. (www)

  @article{ , abstract = {The properties of host galaxies associated with fast radio bursts (FRBs) provide critical information for inferring the progenitors and radiation mechanisms of these bursts. We report on the host galaxy of the repeating FRB 20190520B, a dwarf galaxy at the spectroscopic redshift z = 0.241 with a stellar mass of (6.2 ± 0.8) × 10 8 M ⊙ . The emission-line ratios suggest that the ionized gas is powered by star formation. The total H α -traced star formation rate (SFR) is 0.70 ± 0.01 M ⊙ yr −1 , and the metallicity is 12+{{\rm{log}}}_{10}([{\rm{O}}/{\rm{H}}])\geqslant 7.4\pm 0.1 . The specific star formation rate (sSFR) is {\rm{log}}\,{{\rm{sSFR/yr}}}^{-1}=-9.0\pm 0.1 , higher than the upper limit of −9.4 observed in nearby dwarf galaxies. The dispersion measure (DM) contribution from the host galaxy is estimated to be DM host ≈ 950 ± 220 pc cm −3 , based on the H α emission. The FRB and the associated persistent radio source are located at the H α emission peak, offset by ∼1 \mathop{.}\limits^{{\rm{^{\prime} }}} 4 (5.5 kpc) in projection from the stellar continuum. At this position, the lower limit of \mathrm{log}\,\mathrm{sSFR}/{\mathrm{yr}}^{-1} is −8.5 ± 0.1, more than 3 times the galaxy's total sSFR. The H α velocity difference between the stellar continuum and the offset gas is 39.6 ± 0.4 km s −1 , which is sufficient to draw conclusions about the nature of the offset.}, archive = {J_ApJ}, author = {Xiang-Lei Chen and Chao-Wei Tsai and Daniel Stern and Christopher D. Bochenek and Shami Chatterjee and Casey Law and Di Li and Chen-hui Niu and Yuu Niino and Yi Feng and Pei Wang and Roberto J. Assef and Guo-dong Li and Sean E. Lake and Gan Luo and Mai Liao}, doi = {10.3847/1538-4357/adb84d}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {203}, shortjournal = {The Astrophys. J.}, title = {The host galaxy of FRB 20190520B and its unique ionized gas distribution}, volume = {982}, year = {2025}, }
• (2025). Determining the polarization of a coronal standing kink oscillation using spectral imaging techniques with CoMP. ApJ, 982(2), 202. (www)

  @article{ , abstract = {Coronal oscillations offer insight into energy transport and driving in the solar atmosphere. Knowing its polarization state helps constrain a wave's displacement and velocity amplitude, improving estimates of wave energy flux and deposition rate. We demonstrate a method to combine imaging and spectral data to infer the polarization of a coronal loop's standing kink wave, without the need for multiple instruments or multiple lines of sight. We use the unique capabilities of the Coronal Multi-channel Polarimeter (CoMP) to observe the standing kink mode of an off-limb coronal loop perturbed by an eruption. The full off-disk corona is observed using the 1074 nm Fe xiii spectral line, providing Doppler velocity, intensity, and line width. By tracking the oscillatory motion of a loop apex in a time–distance map, we extract the line-of-sight (Doppler) velocity of the inhomogeneity as it sways and compare it with the derivative of its plane-of-sky displacement. This analysis provides the loop's velocity in two perpendicular planes as it oscillates with a period of 8.{9}_{-0.5}^{+0.5} minutes. Through detailed analysis of the phase relation between the transverse velocities, we infer the kink oscillation to be horizontally polarized, oscillating in a plane tilted -13\mathop{.}\limits^{{\rm{^\circ }}}{6}_{-3.0}^{+2.9} away from the plane of sky. The line widths show a periodic enhancement during the kink oscillation, exhibiting both the kink period and its double. This study is the first to combine direct imaging and spectral data to infer the polarization of a coronal loop oscillation from a single viewpoint.}, archive = {J_ApJ}, author = {T. J. Duckenfield and D. B. Jess and R. J. Morton and S. Jafarzadeh}, doi = {10.3847/1538-4357/adb8d6}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {202}, shortjournal = {The Astrophys. J.}, title = {Determining the polarization of a coronal standing kink oscillation using spectral imaging techniques with CoMP}, volume = {982}, year = {2025}, }
• (2025). Stellar evolution along the asymptotic giant branch as revealed by the shape of miras’ visual light curves. ApJ, 982(2), 201. (www)

  @article{ , abstract = {A new analysis of a sample of visual light curves of Mira variables is presented. The curves cover the past four decades and are selected from the AAVSO database as including a large number of high-density observations. The aim is to offer a more quantitative and more systematic picture than available from earlier studies. The results corroborate earlier descriptions and reveal new correlations between the shapes of the light curves and the evolution of the star along the asymptotic giant branch (AGB). A family of nearly sinusoidal curves associated with M spectral types and displaying no sign of having experienced third-dredge-up events is identified with confidence. A detailed study of its properties is presented and used to suggest possible interpretations. All other curves are distinct from this family and start departing from it by displaying a broader luminosity minimum, progressively taking the form of a hump climbing the ascending branch. Possible relations between such progression and the evolution of the star along the AGB are discussed. New correlations between parameters defining the shape of the light curve and the state of the star are revealed; while the average trend is established with confidence, deviations from it cause a significant scatter of the parameters of the curves. Comments aimed at shedding light on the underlying physics are presented together with speculative interpretations, in the hope that they could encourage and inspire new studies, in particular based on models of the inner star dynamics.}, archive = {J_ApJ}, author = {Do Thi Hoai and Pham Tuyet Nhung and Pierre Darriulat and Mai Nhat Tan}, doi = {10.3847/1538-4357/adb8d9}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {201}, shortjournal = {The Astrophys. J.}, title = {Stellar evolution along the asymptotic giant branch as revealed by the shape of miras’ visual light curves}, volume = {982}, year = {2025}, }
• (2025). The evolution of the size and merger fraction of submillimeter galaxies across 1 < z ≲ 6 as observed by JWST. ApJ, 982(2), 200. (www)

  @article{ , abstract = {Precise tracking of the growth in galaxy size and the evolution of merger fractions with redshift is vital for understanding the formation history of submillimeter galaxies (SMGs). This study investigates this evolution over a broad redshift range (1 < z ≲ 6) using a sample of 222 SMGs with a median redshift of z=2.6{1}_{-0.82}^{+0.89} identified by the Atacama Large Millimeter/submillimeter Array and the James Clerk Maxwell Telescope, enhanced by the advanced imaging capabilities of the JWST/NIRCam and MIRI. We find significant evolution in effective radii ( R e ) in the rest-frame V band ( R e ∝ (1 + z ) −0.87 ± 0.08 ) and near-infrared (NIR) band ( R e ∝ (1 + z ) −0.88 ± 0.11 ), with the NIR size evolution resembling that of massive star-forming galaxies (SFGs) at lower redshift. Visual inspections reveal a major merger fraction of 24.3% ± 3.7% and an interaction fraction of up to 48.4% ± 11.1%. The major merger fraction exhibits an increase from 14.7% ± 9.1% at z = 1 to 26.6% ± 8.4% at z = 3, after which it remains approximately constant across the redshift range 3 < z < 6. In contrast, the interaction fraction remains relatively stable across the range 2 < z < 5. Our results indicate that late-stage major mergers are not the primary formation mechanism for SMGs at z < 3, while interactions appear to play a significant role across the broader redshift range of 1 < z < 6. Additionally, Hubble Space Telescope–based major merger identifications may overestimate the true fraction by a factor of 1.7 at z ∼ 2. These findings highlight the varying roles of mergers and interactions in driving the formation of massive, dusty SFGs across different redshifts.}, archive = {J_ApJ}, author = {Jian Ren and F. S. Liu and Nan Li and Pinsong Zhao and Qifan Cui and Qi Song and Yubin Li and Hao Mo and Hassen M. Yesuf and Weichen Wang and Fangxia An and Xian Zhong Zheng}, doi = {10.3847/1538-4357/adb961}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {200}, shortjournal = {The Astrophys. J.}, title = {The evolution of the size and merger fraction of submillimeter galaxies across 1 < z ≲ 6 as observed by JWST}, volume = {982}, year = {2025}, }
• (2025). Emergence of two inertial subranges in solar wind turbulence: Dependence on heliospheric distance and solar activity. ApJ, 982(2), 199. (www)

  @article{ , abstract = {The solar wind is highly turbulent, and intermittency effects are observed for fluctuations within the inertial range. By analyzing magnetic field spectra and fourth-order moments, we perform a comparative study of turbulence and intermittency in different types of solar wind, measured during periods of solar minima and a maximum. Using eight fast-solar-wind intervals measured during solar minima between 0.3 and 3.16 au, we find a clear signature of two inertial subranges with f −3/2 and f −5/3 power laws in the magnetic power spectra. The intermittency, measured through the scaling law of the kurtosis of the magnetic field fluctuations, further confirms the existence of two different power laws separated by a clear break. A systematic study of the evolution of the said subranges as a function of heliospheric distance shows the correlation of the break scale with both the turbulence outer scale and the typical ion scales. During solar maximum, on the contrary, the two subranges are not omnipresent, thus showing more variability in the power spectra and intermittency scaling properties.}, archive = {J_ApJ}, author = {Shiladittya Mondal and Supratik Banerjee and Luca Sorriso-Valvo}, doi = {10.3847/1538-4357/adba54}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {199}, shortjournal = {The Astrophys. J.}, title = {Emergence of two inertial subranges in solar wind turbulence: Dependence on heliospheric distance and solar activity}, volume = {982}, year = {2025}, }
• (2025). Investigating the temperature sensitivity of UV line ratios in the 280 nm region of solar-like stars. ApJ, 982(2), 198. (www)

  @article{ , abstract = {Stellar UV spectra are fundamental diagnostics of physical and magnetic properties of stars. For instance, lines like Mg ii at 280 nm serve as valuable indicators of stellar activity, providing insights into the activity levels of Sun-like stars and their potential influence on the atmospheres of orbiting planets. On the other hand, the effective temperature ( T eff ) is a fundamental stellar parameter, critical for determining stellar properties such as mass, age, composition, and evolutionary status. In this study, we investigate the temperature sensitivity of three lines in the mid-UV range (i.e., Mg ii 280.00 nm, Mg i 285.20 nm, and Si i 286.15 nm). Using spectra from the International Ultraviolet Explorer, we analyze the behavior of the ratios of their corresponding indices (core/continuum) for a sample of calibrating solar-like stars and find that the ratio R = Mg ii /Mg i best traces T eff through a log–log relation. The T eff estimated using this relation on a test sample of solar-like stars agree with the T eff from the literature at the 95% confidence level. The observed results are interpreted making use of response functions as diagnostics. This study extends the well-established use of line depth ratio–temperature relationships, traditionally applied in the visible and near-infrared ranges, to the mid-UV spectrum. With the growing interest in stellar UV spectroscopy, results presented in this paper are potentially relevant for future missions such as HWO, MANTIS, and UVEX.}, archive = {J_ApJ}, author = {Valentina Penza and Serena Criscuoli and Raffaele Reda and Luca Bertello and Giuseppe Bono and Dario Del Moro and Valentina D’Orazi and Luca Giovannelli and Giuseppina Nigro and Francesco Berrilli}, doi = {10.3847/1538-4357/adbbd5}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {198}, shortjournal = {The Astrophys. J.}, title = {Investigating the temperature sensitivity of UV line ratios in the 280 nm region of solar-like stars}, volume = {982}, year = {2025}, }
• (2025). Cosmic filament spin. i. a comparative study in observation. ApJ, 982(2), 197. (www)

  @article{ , abstract = {In the cosmic web, filaments play a crucial role in connecting walls to clusters and also act as an important stage for galaxy formation and evolution. Recent observational studies claim that filaments have spin. In this study, we examined the potential impact of diversity in filament identification algorithms and galaxy survey data sets on the quantification of filament spin. The results of this study demonstrate qualitative agreement with previous research, suggesting that a reliable filament spin signal is detectable when the viewing angle of the filament spine is larger than 80° under a rough estimation. The detected filament spin signal is intricately linked to the viewing angle, dynamic temperature, etc. The quantitative difference of filament spin signal among samples is slightly dependent on the filament identification algorithms, while the value is relatively greater dependent on the redshift space distortion effect in the galaxy sample.}, archive = {J_ApJ}, author = {Xiao-xiao Tang and Peng Wang and Wei Wang and Ming-Jie Sheng and Hao-Ran Yu and Haojie Xu}, doi = {10.3847/1538-4357/adbbd7}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {197}, shortjournal = {The Astrophys. J.}, title = {Cosmic filament spin. i. a comparative study in observation}, volume = {982}, year = {2025}, }
• (2025). Revisiting X-ray afterglows of jetted tidal disruption events with the external reverse shock. ApJ, 982(2), 196. (www)

  @article{ , abstract = {We investigate the external reverse shock (RS) region of relativistic jets as the origin of X-ray afterglows of jetted tidal disruption events (TDEs) that exhibit luminous jets accompanied by fast-declining nonthermal X-ray emissions. We model the dynamics of jet propagating within an external density medium, accounting for continuous energy injection driven by accretion activities. We compute the time-dependent synchrotron and inverse Compton emissions from the RS region. Our analysis demonstrates that the RS scenario can potentially explain the X-ray light curves and spectra of four jetted TDEs, namely, AT 2022cmc, Swift J1644, Swift J2058, and Swift J1112. Notably, the rapid steepening of the late-stage X-ray light curves can be attributed jointly to the jet break and cessation of the central engine as the accretion rate drops below the Eddington limit. Using parameters obtained from X-ray data fitting, we also discuss the prospects for γ -ray and neutrino detection.}, archive = {J_ApJ}, author = {Chengchao Yuan and Walter Winter and B. Theodore Zhang and Kohta Murase and Bing Zhang}, doi = {10.3847/1538-4357/adbbde}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {196}, shortjournal = {The Astrophys. J.}, title = {Revisiting X-ray afterglows of jetted tidal disruption events with the external reverse shock}, volume = {982}, year = {2025}, }
• (2025). The origin of the nano-hertz stochastic gravitational-wave background: The contribution from z ≳ 1 supermassive black hole binaries. ApJ, 982(2), 195. (www)

  @article{ , abstract = {The nano-Hertz gravitational wave background (GWB) is a key probe of supermassive black hole (SMBH) formation and evolution if the background arises predominantly from SMBH binaries (SMBHBs). The GWB amplitude, which is typically quantified as the characteristic strain, A yr at a frequency 1 yr −1 , encodes significant astrophysical information about the SMBHB population, including the SMBHB mass and redshift distributions. Recent results from a number of pulsar timing arrays have identified a common-spectrum noise process, correlated between pulsars, that is consistent with a loud GWB signal with A yr ∼ 2 × 10 −15 , which is higher than most predictions A yr ≲ 10 −15 . These predictions usually assume theoretically motivated but highly uncertain prescriptions for SMBH seeding and evolution. Recent observations, largely by the James Webb Space Telescope, have uncovered a population of obscured, overmassive, accreting black holes in the early Universe that may suggest that the black hole mass density and net accretion were larger at high redshifts than previously thought. In this work, we use two simple, flexible models of SMBH evolution to explore the possible range of GWB amplitudes, given observational constraints. In particular, we explore enhanced contributions to the GWB from high redshift ( z ≳ 1) SMBHBs. We find that the GWB amplitude may be higher than fiducial predictions by as much as ∼1 dex if much of the SMBH mass density was established by z ∼ 1. Beyond pulsar timing constraints, further observations of the high redshift SMBH population from the James Webb Space Telescope and the Laser Interferometer Space Antenna will be key for constraining the GWB contribution of mid-high- z SMBHBs.}, archive = {J_ApJ}, author = {Jean J. Somalwar and Vikram Ravi}, doi = {10.3847/1538-4357/adbc62}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {195}, shortjournal = {The Astrophys. J.}, title = {The origin of the nano-hertz stochastic gravitational-wave background: The contribution from z ≳ 1 supermassive black hole binaries}, volume = {982}, year = {2025}, }
• (2025). How the CME on 2023 april 21 triggered the first severe geomagnetic storm of solar cycle 25. ApJ, 982(2), 194. (www)

  @article{ , abstract = {The first severe (G4) geomagnetic storm of Solar Cycle 25 occurred on 2023 April 23–24, following the arrival of a coronal mass ejection (CME) on April 23. The characteristics of this CME, measured from coronagraphs (speed and mass), did not indicate that it would trigger such an intense geomagnetic storm. In this work, our aim is to understand why this CME led to such a geoeffective outcome. Our analysis spans from the source active region to the corona and inner heliosphere through 1 au using multiwavelength, multi-viewpoint remote sensing observations and in situ data. We find that rotation and possibly deflection of the CME resulted in an axial magnetic field nearly parallel to the ecliptic plane during the Earth encounter, which might explain the storm's severity. Additionally, we find that imaging away from the Sun–Earth line is crucial in hindcasting the CME time of arrival at Earth. The position (0.39 au) and detailed images from the SoloHI telescope on board the Solar Orbiter mission, in combination with SOHO and STEREO images, helped decisively with the three-dimensional reconstruction of the CME.}, archive = {J_ApJ}, author = {Evangelos Paouris and Angelos Vourlidas and Manolis K. Georgoulis and Phillip Hess and Guillermo Stenborg}, doi = {10.3847/1538-4357/adb8d3}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {194}, shortjournal = {The Astrophys. J.}, title = {How the CME on 2023 april 21 triggered the first severe geomagnetic storm of solar cycle 25}, volume = {982}, year = {2025}, }
• (2025). How does a protostar form by magnetized gravitational collapse?. ApJ, 982(2), 193. (www)

  @article{ , abstract = {Star formation through dynamical magnetized collapse remains an area of active astrophysical research. We carry out a comprehensive exploration on the magnetized gravitational collapse of a nonrotating self-gravitating initially spherically symmetric prestellar cloud core using two-dimensional nonideal magnetohydrodynamic simulations incorporating ambipolar diffusion and ohmic dissipation. Our study encompasses a broader range of equations of state (EOSs) in the form of P ( ρ ) ∝ ρ Γ , with the aim of constraining the choice of EOSs for allowing star formation. Our results reveal that the collapse with a Γ no stiffer than 4/3, complemented by magnetized virial theorem, allows the dynamical contraction of the prestellar core to happen continuously where a central point mass forms and steadily builds up its mass from the infalling envelope, with a mass accretion rate of the order of {c}_{{\rm{s}}}^{3}/G . The choice of an isothermal EOS most naturally facilitates the collapse as a magnetic analog of the inside-out collapse. In addition to that, our study exhibits that the nonisothermal magnetized collapse models with a Γ no stiffer than 4/3 qualitatively demonstrate similar infall features to those of an isothermal EOS. Furthermore, the collapse models with a Γ stiffer than 4/3 fail to ensure sufficient cooling to allow the direct mass growth of the central point mass, thus delaying the infall. Our work can offer deeper insights in understanding the significance of EOSs on the magnetized gravitational collapse, enabling star formation.}, archive = {J_ApJ}, author = {Indrani Das and Hsien Shang and Ruben Krasnopolsky}, doi = {10.3847/1538-4357/adace6}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {193}, shortjournal = {The Astrophys. J.}, title = {How does a protostar form by magnetized gravitational collapse?}, volume = {982}, year = {2025}, }
• (2025). The halo occupation distribution modeling of X-ray-selected active galactic nuclei at 0.6 < z < 2.6 in the COSMOS field. ApJ, 982(2), 192. (www)

  @article{ , abstract = {We conduct precise measurements of active galactic nucleus (AGN) clustering at z ∼ 1 and z ∼ 2 by measuring the two-point cross-correlation function (CCF) between galaxies and X-ray-selected AGNs, and the two-point autocorrelation function (ACF) of galaxies in the COSMOS field, to interpret the CCF results. The galaxy sample was selected from the COSMOS2015 catalog, while the AGN sample was chosen from the Chandra-COSMOS Legacy Survey catalog. For the AGN samples at z ∼ 1 and z ∼ 2, we calculated AGN bias values of b = 1.16 (1.16; 1.31) and b = 2.95 (2.30; 3.55), respectively. These values correspond to typical host dark matter halo (DMH) masses of log( M typ / M ⊙ ) = 11.82 (11.82; 12.12) and log( M typ / M ⊙ ) = 12.80 (12.38; 13.06), respectively. Subsequently, we performed halo occupation distribution (HOD) modeling of X-ray-selected AGNs using the CCF and ACF of galaxies. We found a significant satellite AGN population at z ∼ 1 all over the DMH mass ( M DMH ) range occupied by AGNs, while z ∼ 2 AGNs in our sample are associated with higher-mass DMHs and smaller satellite fractions. The HOD analysis suggests a marginal tendency of increasing satellite slope with redshift, but larger samples are needed to confirm this with sufficient statistical significance. We find that the best-fit values of the satellite slope in both redshift bins are greater than 0, suggesting a tendency of increasing satellite AGN number with M DMH .}, archive = {J_ApJ}, author = {Hiroyuki Ikeda and Takamitsu Miyaji and Taira Oogi and Yoshiki Toba and Héctor Aceves and Stefano Marchesi and Viola Allevato and Akke Viitanen and Francesca Civano}, doi = {10.3847/1538-4357/adb719}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {192}, shortjournal = {The Astrophys. J.}, title = {The halo occupation distribution modeling of X-ray-selected active galactic nuclei at 0.6 < z < 2.6 in the COSMOS field}, volume = {982}, year = {2025}, }
• (2025). The missing link of sulfur chemistry in TMC-1: The detection of c-C3H2S from the GOTHAM survey. ApJ, 982(2), 191. (www)

  @article{ , abstract = {We present the spectroscopic characterization of cyclopropenethione in the laboratory and detect it in space using the Green Bank Telescope Observations of TMC-1: Hunting Aromatic Molecules survey. The detection of this molecule—the missing link in understanding the C 3 H 2 S isomeric family in TMC-1—completes the detection of all three low-energy isomers of C 3 H 2 S, as both CH 2 CCS and HCCCHS have been previously detected in this source. The total column density of this molecule ( N T of 5.7{2}_{-1.61}^{+2.65}\times 1{0}^{10} cm −2 at an excitation temperature of 4.{7}_{-1.1}^{+1.3} K) is smaller than both CH 2 CCS and HCCCHS and follows nicely the relative dipole principle (RDP), a kinetic rule of thumb for predicting isomer abundances that suggests that, all other chemistry among a family of isomers being the same, the member with the smallest dipole ( μ ) should be the most abundant. The RDP now holds for the astronomical abundance ratios of both the S-bearing and O-bearing counterparts observed in TMC-1; however, CH 2 CCO continues to elude detection in any astronomical source.}, archive = {J_ApJ}, author = {Anthony J. Remijan and P. Bryan Changala and Ci Xue and Elsa Q. H. Yuan and Miya Duffy and Haley N. Scolati and Christopher N. Shingledecker and Thomas H. Speak and Ilsa R. Cooke and Ryan Loomis and Andrew M. Burkhardt and Zachary T. P. Fried and Gabi Wenzel and Andrew Lipnicky and Michael C. McCarthy and Brett A. McGuire}, doi = {10.3847/1538-4357/adb84c}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {191}, shortjournal = {The Astrophys. J.}, title = {The missing link of sulfur chemistry in TMC-1: The detection of c-C3H2S from the GOTHAM survey}, volume = {982}, year = {2025}, }
• (2025). Measurement of the forward shock velocities of the supernova remnant N132D based on the thermal X-ray emission. ApJ, 982(2), 190. (www)

  @article{ , abstract = {Measuring shock velocities is crucial for understanding the energy transfer processes at the shock fronts of supernova remnants (SNRs), including acceleration of cosmic rays. Here we present shock velocity measurements on the SNR N132D, based on the thermal properties of the shock-heated interstellar medium. We apply a self-consistent model developed in our previous work to X-ray data from deep Chandra observations with an effective exposure of ∼900 ks. In our model, both temperature and ionization relaxation processes in postshock plasmas are simultaneously calculated, so that we can trace back to the initial condition of the shock-heated plasma to constrain the shock velocity. We reveal that the shock velocity ranges from 800 to 1500 km s −1 with moderate azimuthal dependence. Although our measurement is consistent with the velocity determined by independent proper motion measurements in the south rim regions, a large discrepancy between the two measurements (up to a factor of 4) is found in the north rim regions. This implies that a substantial amount of the kinetic energy has been transferred to the nonthermal component through highly efficient particle acceleration. Our results are qualitatively consistent with the gamma-ray observations of this SNR.}, archive = {J_ApJ}, author = {Yoshizumi Okada and Yuken Ohshiro and Shunsuke Suzuki and Hiromasa Suzuki and Paul P. Plucinsky and Ryo Yamazaki and Hiroya Yamaguchi}, doi = {10.3847/1538-4357/adb8cb}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {190}, shortjournal = {The Astrophys. J.}, title = {Measurement of the forward shock velocities of the supernova remnant N132D based on the thermal X-ray emission}, volume = {982}, year = {2025}, }
• (2025). Do red galaxies form more stars than blue galaxies?. ApJ, 982(2), 189. (www)

  @article{ , abstract = {A new model is proposed in which typical galaxies form most of their stellar mass in a phase with an intrinsically red stellar population. In the standard picture, galaxies with intrinsically red stellar populations are believed to have old stellar populations, so that only galaxies with blue stellar populations have significant star formation, and subsequent changes to the stellar population come predominantly from aging and merging populations that have already formed. However, several observational puzzles have developed that are difficult to reconcile with this standard scenario. The most massive blue star-forming galaxies, presumed to be at the end of their stellar mass growth, are ∼1 dex less massive, have a ∼1 dex lower M * / M BH ratio, and have a bottom-lighter IMF than local quiescent galaxies. Here, a new solution is proposed: at low temperature and high metallicity, galaxies can continue to form stars efficiently without being able to form O and B stars. These red star-forming galaxies would have many of the same properties of the population currently described as post-starburst galaxies, allowing a new interpretation of their origin. Finally, additional falsifiable observational predictions of this model are also discussed.}, archive = {J_ApJ}, author = {Charles L. Steinhardt}, doi = {10.3847/1538-4357/adb95b}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {189}, shortjournal = {The Astrophys. J.}, title = {Do red galaxies form more stars than blue galaxies?}, volume = {982}, year = {2025}, }
• (2025). Hypervelocity stars trace a supermassive black hole in the large magellanic cloud. ApJ, 982(2), 188. (www)

  @article{ , abstract = {Hypervelocity stars (HVSs) are produced by the Hills mechanism when a stellar binary is disrupted by a supermassive black hole (SMBH). The HVS Survey detected 21 unbound B-type main-sequence stars in the Milky Way's outer halo that are consistent with ejection via the Hills mechanism. We revisit the trajectories of these stars in light of proper motions from Gaia DR3 and modern constraints on the Milky Way–Large Magellanic Cloud (LMC) orbit. We find that half of the unbound HVSs discovered by the HVS Survey trace back not to the Galactic Center but to the LMC. Motivated by this finding, we construct a forward model for HVSs ejected from an SMBH in the LMC and observed through the selection function of the HVS Survey. The predicted spatial and kinematic distributions of the simulated HVSs are remarkably similar to the observed distributions. In particular, we reproduce the conspicuous angular clustering of HVSs around the constellation Leo. This clustering occurs because HVSs from the LMC are boosted by  ∼300 km s −1 by the orbital motion of the LMC, and stars launched parallel to this motion are preferentially selected as HVS candidates. We find that the birth rate and clustering of LMC HVSs cannot be explained by supernova runaways or dynamical ejection scenarios not involving an SMBH. From the ejection velocities and relative number of Magellanic versus Galactic HVSs, we constrain the mass of the LMC SMBH to be 1{0}^{5.{8}_{-0.4}^{+0.2}}\,{M}_{\odot } (≃6 × 10 5 M ⊙ ).}, archive = {J_ApJ}, author = {Jiwon Jesse Han and Kareem El-Badry and Scott Lucchini and Lars Hernquist and Warren Brown and Nico Garavito-Camargo and Charlie Conroy and Re’em Sari}, doi = {10.3847/1538-4357/adb967}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {188}, shortjournal = {The Astrophys. J.}, title = {Hypervelocity stars trace a supermassive black hole in the large magellanic cloud}, volume = {982}, year = {2025}, }
• (2025). The hot accretion flow evolution in the black hole X-ray binary MAXI j1348-630. ApJ, 982(2), 187. (www)

  @article{ , abstract = {MAXI J1348-630, as a low-mass black hole binary system in the Galaxy, showed an X-ray outburst in 2019. We analyzed the Insight Hard X-ray Modulation Telescope spectral data in the low hard state and intermediate state during the outburst from MJD 58510 to 58519 at the energy band from 2 to 100 keV. During the entire process, a thin disk extending to the innermost stable circular orbit (ISCO) from a large truncated disk (truncated radius >5 ISCO) suggested the corona geometry evolution. There exist time lags between the radio and hard X-ray flux peaks: the 30–100 keV flux is about 5 days ahead of the radio flux, the 11–30 keV flux is about 4 days ahead, and the reflection fraction is about 2 days ahead, with the accretion disk approaching the ISCO about 1 day before radio peak. This disk–corona–jet coupling and evolution suggest the corona contains two phases of cold dense material and hot gas, with the high-temperature region of the corona cooling fast. The strong radio emission accompanying a thin accretion disk with a relatively high accretion rate favors a magnetic tower jet mechanism.}, archive = {J_ApJ}, author = {Hanji Wu and Wei Wang}, doi = {10.3847/1538-4357/adbdb9}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {187}, shortjournal = {The Astrophys. J.}, title = {The hot accretion flow evolution in the black hole X-ray binary MAXI j1348-630}, volume = {982}, year = {2025}, }
• (2025). Superclustering with the atacama cosmology telescope and dark energy survey. II. anisotropic large-scale coherence in hot gas, galaxies, and dark matter. ApJ, 982(2), 186. (www)

  @article{ , abstract = {Statistics that capture the directional dependence of the baryon distribution in the cosmic web enable unique tests of cosmology and astrophysical feedback. We use constrained oriented stacking of thermal Sunyaev–Zel'dovich (tSZ) maps to measure the anisotropic distribution of hot gas 2.5–40 Mpc away from galaxy clusters embedded in massive filaments and superclusters. The cluster selection and orientation (at a scale of ∼15 Mpc) use Dark Energy Survey (DES) Year 3 data, while expanded tSZ maps from the Atacama Cosmology Telescope Data Release 6 enable a ∼3 × more significant measurement of the extended gas compared to the technique's proof-of-concept. Decomposing stacks into cosine multipoles of order m , we detect a dipole ( m = 1) and quadrupole ( m = 2) at 8 σ –10 σ , as well as evidence for m = 4 signal at up to 6 σ , indicating sensitivity to late-time non-Gaussianity. We compare to Cardinal simulations with spherical gas models pasted onto dark matter halos. The fiducial tSZ data can discriminate between two models that deplete pressure differently in low-mass halos (mimicking astrophysical feedback), preferring higher average pressure in extended structures. However, uncertainty in the amount of cosmic infrared background contamination reduces the constraining power. Additionally, we apply the technique to DES galaxy density and weak lensing to study for the first time their oriented relationships with tSZ. In the tSZ-to-lensing relation, averaged on 7.5 Mpc (transverse) scales, we observe dependence on redshift but not shape or radial distance. Thus, on large scales, the superclustering of gas pressure, galaxies, and total matter is coherent in shape and extent.}, archive = {J_ApJ}, author = {M. Lokken and A. van Engelen and M. Aguena and S. S. Allam and D. Anbajagane and D. Bacon and E. Baxter and J. Blazek and S. Bocquet and J. R. Bond and D. Brooks and E. Calabrese and A. Carnero Rosell and J. Carretero and M. Costanzi and L. N. da Costa and W. R. Coulton and J. De Vicente and S. Desai and P. Doel and C. Doux and A. J. Duivenvoorden and J. Dunkley and Z. Huang and S. Everett and I. Ferrero and J. Frieman and J. García-Bellido and M. Gatti and E. Gaztanaga and G. Giannini and Vera Gluscevic and D. Gruen and R. A. Gruendl and Y. Guan and G. Gutierrez and S. R. Hinton and R. Hlozek and D. L. Hollowood and K. Honscheid and D. J. James and K. Kuehn and O. Lahav and S. Lee and Z. Li and M. Madhavacheril and G. A. Marques and J. L. Marshall and J. Mena-Fernández and F. Menanteau and R. Miquel and J. Myles and M. D. Niemack and S. Pandey and M. E. S. Pereira and A. Pieres and A. A. Plazas Malagón and A. Porredon and M. Rodríguez-Monroy and A. Roodman and S. Samuroff and E. Sanchez and D. Sanchez Cid and B. Santiago and M. Schubnell and I. Sevilla-Noarbe and C. Sifón and M. Smith and S. T. Staggs and E. Suchyta and M. E. C. Swanson and G. Tarle and C-H. To and N. Weaverdyck and P. Wiseman and E. J. Wollack}, doi = {10.3847/1538-4357/adb622}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {186}, shortjournal = {The Astrophys. J.}, title = {Superclustering with the atacama cosmology telescope and dark energy survey. II. anisotropic large-scale coherence in hot gas, galaxies, and dark matter}, volume = {982}, year = {2025}, }
• (2025). The expanding 3 kpc arms are neither expanding nor spiral arms but x1 orbits driven by the galactic bar. ApJ, 982(2), 185. (www)

  @article{ , abstract = {Near the center of our Milky Way is a bar-like structure and the so-called Expanding 3 kpc arms. We currently have limited knowledge of this important region, since we are about 8.2 kpc from the center and cannot directly observe it at optical wavelengths, owing to strong extinction from interstellar dust. Here we present extremely precise very long baseline interferometry measurements of H 2 O maser sources from the BeSSeL Survey, where extinction is not a problem, which accurately determine the three-dimensional locations and motions of three massive young stars. Combined with previous measurements, these stars delineate a trail of orbits outlining the Milky Way's Galactic bar. We present the first measurements capturing the dynamics of quasi-elliptical (X1) orbits around the Galactic bar. Our findings provide evidence substantiating the existence of such orbits populated by massive young stars. Our measurements of the position and velocity of a number of massive young stars, previously identified with the Expanding 3 kpc arms, show that they are more likely located in the X1 orbits about the Galactic bar. Also, some stars previously assigned to the Norma spiral arm appear to be in these orbits, which suggests that this spiral arm does not extend past the end of the bar.}, archive = {J_ApJ}, author = {Jayender Kumar and Mark J. Reid and T. M. Dame and Simon P. Ellingsen and Lucas J. Hyland and Andreas Brunthaler and Karl M. Menten and Xing-Wu Zheng and Alberto Sanna}, doi = {10.3847/1538-4357/adb70f}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {185}, shortjournal = {The Astrophys. J.}, title = {The expanding 3 kpc arms are neither expanding nor spiral arms but x1 orbits driven by the galactic bar}, volume = {982}, year = {2025}, }
• (2025). Carbon stars from gaia data release 3 and the space density of dwarf carbon stars. ApJ, 982(2), 184. (www)

  @article{ , abstract = {Carbon stars (with atmospheric C/O > 1) range widely in temperature and luminosity, from low-mass dwarfs to asymptotic giant branch (AGB) stars. The main-sequence dwarf carbon (dC) stars have inherited carbon-rich material from an AGB companion, which has since transitioned to a white dwarf. The dC stars are far more common than C giants, but no reliable estimates of the dC space density have been published to date. We present results from an all-sky survey for carbon stars using the low-resolution XP spectra from Gaia Data Release 3. We developed and measured a set of spectral indices contrasting C 2 and CN molecular band strengths in carbon stars against common absorption features found in normal (C/O < 1) stars, such as Ca i , TiO, and Balmer lines. We combined these indices with the XP spectral coefficients as inputs to supervised machine learning algorithms trained on a vetted sample of known C stars from LAMOST. We describe the selection of the carbon candidate sample and provide a catalog of 43,574 candidates dominated by cool C giants in the Magellanic Clouds and at low Galactic latitude in the Milky Way. We report the confirmation of candidate C stars using intermediate-resolution ( R ∼ 1800) optical spectroscopy from the Fred Lawrence Whipple Observatory and provide estimates of the sample purity and completeness. From a carefully vetted sample of over 600 dCs, we measure their local space density to be {\rho }_{0}\,=\,1.9{6}_{-0.12}^{+0.14}\times 1{0}^{-6}\,{\,\rm{pc}\,}^{-3} (about one dC in every local disk volume of radius 50 pc), with a relatively large disk scale height of {H}_{z}\,=\,85{6}_{-43}^{+49}\, pc.}, archive = {J_ApJ}, author = {Benjamin R. Roulston and Naunet Leonhardes-Barboza and Paul J. Green and Evan Portnoi}, doi = {10.3847/1538-4357/adba53}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {184}, shortjournal = {The Astrophys. J.}, title = {Carbon stars from gaia data release 3 and the space density of dwarf carbon stars}, volume = {982}, year = {2025}, }
• (2025). Disparities in magnetic cloud observations between two spacecraft having small radial and angular separations near 1 au. ApJ, 982(2), 183. (www)

  @article{ , abstract = {Studies for inferring the global characteristics of coronal mass ejections (CMEs) from multipoint local in situ observations have been undertaken previously, but limited studies have utilized measurements from multiple spacecraft with sufficiently small radial and angular separations. In the present study, we investigate a magnetic cloud (MC) region of a CME observed in situ during 2023 September 24–26 by the STEREO-A and Wind spacecraft near 1 au, which had radial and angular separations of 0.03 au and 3 \mathop{.}\limits^{\unicode{x000b0}} 4, respectively. We examine the disparities in the estimates of the arrival times of CME substructures, the MC axis, and its orientation between the two spacecraft. We also propose an approach for identifying the MC axis's arrival and have compared it with the arrival of the size center and time center to understand the nonisotropic compression of the MC along its angular extent. Using minimum variance analysis, we note that the orientation of the MC is slightly out of the ecliptic at Wind but not at STEREO-A. We also compare the magnetic field parameters from the start to the end of the MC at both spacecraft and note a significant noncoherency in the MC toward its trailing portion. Our analysis confirms that the MC has a stronger compression at the rear portion at STEREO-A than at Wind, with its trailing edge arriving later at Wind. Our study highlights substantial differences in CME characteristics even at mesoscales across the angular extent, and therefore one needs to analyze several such cases to better understand the flux rope structure.}, archive = {J_ApJ}, author = {Anjali Agarwal and Wageesh Mishra}, doi = {10.3847/1538-4357/adbaeb}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {183}, shortjournal = {The Astrophys. J.}, title = {Disparities in magnetic cloud observations between two spacecraft having small radial and angular separations near 1 au}, volume = {982}, year = {2025}, }
• (2025). Barium abundances of common stars in the gaia-ESO survey and the LAMOST medium-resolution survey. ApJ, 982(2), 182. (www)

  @article{ , abstract = {Barium (Ba) abundance has been used as a crucial tracer of both slow and rapid neutron-capture processes to constrain the evolutionary models of the Galaxy. In this study, we aim to establish a reference sample with high-resolution spectra and high-quality stellar parameters from the Gaia-ESO Survey (GES). This sample explores the non–local thermodynamic equilibrium (NLTE) effects on the Ba abundances and will support future measurements of Ba abundances for the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) medium-resolution survey (MRS). The sample is composed of 85 common stars of LAMOST MRS DR9 and GES DR5.1, complemented by four metal-poor ([Fe/H] < −1 dex) stars from AMBRE-UVES. The stars cover the ranges of stellar parameters as 4152 K ≤ T eff ≤ 6866 K, 1.37 \leqslant \,{\rm{log}}\,g\,\leqslant \, 4.57, and −2.40 dex ≤ [Fe/H] ≤ +0.25 dex. We derive the Ba abundances from three Ba ii absorption lines at λλ 5853, 6141, and 6496 Å of R = 47,000 UVES spectra through the spectral synthesis method using the local thermodynamic equilibrium (LTE) and NLTE assumptions. Compared to the GES catalog, the LTE Ba abundances obtained by us from the Ba ii λ 5853 line are the closest to the GES LTE results. The NLTE hypothesis is found to show various impacts on the three lines. The maximum differences from LTE abundances are 0.2, 0.5, and 0.6 dex for the Ba ii lines at λλ 5853, 6141, and 6496 Å, respectively. The NLTE corrections present opposite signs around [Fe/H] = −2.0 dex for the Ba ii line at λ 5853. Stars with higher temperatures or higher Ba abundances suffer larger NLTE effects. A more consistent result of the three lines confirms the necessity of taking NLTE effects into account when determining the Ba abundances.}, archive = {J_ApJ}, author = {Tian-Yi Chen and Jian-Rong Shi and Hong-Liang Yan and Shuai Liu and Chun-Qian Li and Xiao-Jin Xie and Ze-Ming Zhou and Yao-Jia Tang and Ming-Yi Ding}, doi = {10.3847/1538-4357/adbbe0}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {182}, shortjournal = {The Astrophys. J.}, title = {Barium abundances of common stars in the gaia-ESO survey and the LAMOST medium-resolution survey}, volume = {982}, year = {2025}, }
• (2025). The persistent shift in spin-down rate following the largest crab pulsar glitch rules out external torque variations due to starquakes. ApJ, 982(2), 181. (www)

  @article{ , abstract = {It was previously believed that the long-term persistent increase in the spin-down rate of the Crab pulsar following a glitch is direct evidence of a starquake-induced glitch or at least related to a starquake. Using radio data covering 1710 days following the 2017 glitch, we obtain an extreme persistent increase of the spin-down rate, which allows us to test the two prevailing models related to a starquake through an interrelation analysis between the glitch size (the amplitude of the frequency step at a glitch) and the persistent increase in the spin-down rate of the star. Our results do not support the hypothesis that glitches induce the external torque variation of the Crab pulsar, which may indicate no occurrence of a starquake during the Crab pulsar glitch. This can explain why no changes in the radio and X-ray flux, pulse profile, and spectrum of the Crab pulsar have been observed. We also suggest an internal mechanism due to superfluidity as an explanation for the long-term persistent shift in the spin-down rate of the Crab pulsar following the relatively large glitches.}, archive = {J_ApJ}, author = {Xiao-Ping Zheng and Wei-Hua Wang and Chun Huang and Jian-Ping Yuan and Sheng-Jie Yuan}, doi = {10.3847/1538-4357/adbca6}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {181}, shortjournal = {The Astrophys. J.}, title = {The persistent shift in spin-down rate following the largest crab pulsar glitch rules out external torque variations due to starquakes}, volume = {982}, year = {2025}, }
• (2025). A systematic study of millihertz quasiperiodic oscillations in GS 1826−238. ApJ, 982(2), 180. (www)

  @article{ , abstract = {We performed a systematic investigation of millihertz quasiperiodic oscillations (mHz QPOs) in the low-mass X-ray binary GS 1826−238 observed with NICER and Insight-HXMT. We discovered 37 time intervals exhibiting mHz QPOs out of 106 Good Time Interval (GTI) samples in the frequency range of 3–17 mHz at a significance level of >99.99%. The source remains in a soft state in our study. No significant differences are found between the samples with and without mHz QPOs according to positions in the color–color and hardness–intensity diagrams. These QPOs were discovered at an accretion rate of \sim 0.1{\dot{M}}_{{\rm{Edd}}} , similar to other sources. The broadband spectrum of GS 1826–238 can be modeled as a combination of a multicolor blackbody from the accretion disk and a Comptonization with seed photons emitted from the neutron star (NS) surface. The flux modulations of mHz QPOs are related to variations of the temperature of Comptonization seed photons, consistent with the marginally stable burning theory.}, archive = {J_ApJ}, author = {Hua Xiao and Long Ji and Sergey Tsygankov and Yupeng Chen and Shu Zhang and Zhaosheng Li}, doi = {10.3847/1538-4357/adbcaa}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {180}, shortjournal = {The Astrophys. J.}, title = {A systematic study of millihertz quasiperiodic oscillations in GS 1826−238}, volume = {982}, year = {2025}, }
• (2025). The neutron star merger delay-time distribution, R-process “Knees,” and the metal budget of the galaxy. ApJ, 982(2), 179. (www)

  @article{ , abstract = {For a sample of 18 currently known recycled millisecond pulsars (rMSPs) that are in double neutron star (DNS) systems, and 42 rMSPs with similar properties that are not in DNS pairs, we analyze the distributions of the characteristic age, τ c , and the time-until-merger of the double systems, τ gw . Based on the τ c distribution of non-DNS rMSPs, we argue that τ c is a reasonable estimator of true pulsar age and that rMSPs are active as pulsars for a long (≳Hubble) time. Among the DNSs there is an excess of young systems (small τ c ) with short life expectancy (small τ gw ) compared to model expectations for the distributions of τ c and τ gw if, at birth, DNSs have a delay-time distribution (DTD) of the form \sim {\tau }_{{\rm{gw}}}^{-1} (expected generically for close binaries), or for that matter, from expectations from any single power-law DTD. A two-population DNS model solves the problem: the data are best fit by the combination of a "fast" population with DTD going as {\tau }_{{\rm{gw}}}^{-1.9\pm 0.4} , and a "slow" population of DNSs, with DTD proportional to {\tau }_{{\rm{gw}}}^{-1.1\pm 0.15} . The fast population can be equivalently represented by a shallow power-law DTD with an exponential cutoff beyond τ gw ∼ 300 Myr. The fast population completely dominates, by a factor A ≈ 10–100, the numbers of DNSs that merge within a Hubble time, and that presumably lead to short gamma-ray bursts and kilonova explosions. Using a simple, empirically based, chemical-evolution calculation, we show that the fast/steep kilonova DTD, convolved with the measured star formation history of the Milky Way's thick-disk population, naturally reproduces the "knee" structure seen in abundance-ratio diagrams of thick-disk stars, for europium and for two other r -process elements. As a corollary, we show, based again solely on empirical input concerning iron production by supernovae, that the Milky Way is nearly a "closed box" that has retained at least ∼70%–90% of the metals produced over the Galaxy's lifetime.}, archive = {J_ApJ}, author = {Dan Maoz and Ehud Nakar}, doi = {10.3847/1538-4357/ada3bd}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {179}, shortjournal = {The Astrophys. J.}, title = {The neutron star merger delay-time distribution, R-process “Knees,” and the metal budget of the galaxy}, volume = {982}, year = {2025}, }
• (2025). The average stellar population age and metallicity of intermediate-redshift quiescent galaxies. ApJ, 982(2), 178. (www)

  @article{ , abstract = {The HectoMAP spectroscopic survey provides a unique mass-limited sample of more than 35,000 quiescent galaxies ( D n 4000 > 1.5) covering the redshift range 0.2 < z < 0.6. We segregate galaxies in bins of properties based on stellar mass, D n 4000, and redshift to construct a set of high signal-to-noise spectra representing a massive ( M * > 10 10 M ⊙ ) quiescent population at intermediate redshift. These high-quality summed spectra enable full spectrum fitting and the related extraction of the average stellar population age and metallicity. The average galaxy age increases with the central D n 4000 as expected. The correlation is essentially invariant with stellar mass; thus, D n 4000 is a robust proxy for quiescent galaxy stellar population age. HectoMAP provides the first quiescent sample at intermediate redshift comparable with z ∼ 0 mass-complete data sets. Scaling relations derived from the HectoMAP summed spectra connect stellar age and metallicity with quiescent galaxy stellar mass up to z ∼ 0.5. Anticorrelation between the equivalent width (EW) of the [O ii ] emission line and stellar age, together with the mild increase in stellar age with stellar mass, supports a broad range of timescales for the mass assembly of intermediate-redshift quiescent systems. On average, the most massive galaxies ( M * > 10 11 M ⊙ ) assemble the bulk of their stars at earlier epochs. A strong increase in the average stellar metallicity with stellar mass, along with the correlation between the [O ii ] EW and metallicity at 0.2 < z < 0.4, suggests that lower mass galaxies are more likely to have experienced recent star formation episodes; related feedback from massive stars affects the chemical enrichment of these galaxies.}, archive = {J_ApJ}, author = {Ivana Damjanov and Margaret J. Geller and Jubee Sohn}, doi = {10.3847/1538-4357/ada3c5}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {178}, shortjournal = {The Astrophys. J.}, title = {The average stellar population age and metallicity of intermediate-redshift quiescent galaxies}, volume = {982}, year = {2025}, }
• (2025). Redshift drift effect through the observation of the h i 21 cm signal with SKA. ApJ, 982(2), 177. (www)

  @article{ , abstract = {This study presents the findings of using the Square Kilometre Array (SKA) telescope to measure redshift drift via the H i 21 cm signal, employing semiannual observational intervals within a redshift of around z ∼ 1 with a main goal of directly gauging the Universe's expansion acceleration rate with mm s −1 precision. The SKA can detect over 1 billion H i 21 cm emissions from individual galaxies to redshift z ∼ 2 and thousands of absorption lines from damped Ly α systems against bright quasars to redshift z ∼ 13 with a sensitivity limit of 100 mJy. By utilizing SKA's high spectral resolution settings (0.001, 0.002, 0.005, 0.01 Hz) to detect redshift drift, particularly focusing on the 0.001 and 0.002 Hz configuration, one aims to achieve the necessary mm s −1 in precision measurement by the 0.5 yr observation period. The velocity drift rate, crucially determined by the two operational regimes within 0.01–0.21 mm s −1 and 0.031–0.17 mm s −1 , exceeds the theoretical accuracy limit of 1.28 mm s −1 . The analysis thoroughly restricts cosmological parameters related to dark energy using the Sandage–Loeb (SL) signal from the H i 21 cm emission and absorption lines. It estimates a H 0 of about 70 km s −1 Mpc −1 , Ω m near 0.3, and w close to −1, w 0 around −1, and w a approaching −0.1. These results strongly endorse the SL effect as an effective method for confirming cosmic acceleration and exploring the dark sector in real-time cosmology with the SKA.}, archive = {J_ApJ}, author = {Jiangang Kang and Tong-Jie Zhang and Peng He and Ming Zhu}, doi = {10.3847/1538-4357/adae89}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {177}, shortjournal = {The Astrophys. J.}, title = {Redshift drift effect through the observation of the h i 21 cm signal with SKA}, volume = {982}, year = {2025}, }
• (2025). Submillimeter variability in the envelope and warped protostellar disk of the class 0 protostar HOPS 358. ApJ, 982(2), 176. (www)

  @article{ , abstract = {The James Clerk Maxwell Telescope (JCMT) Transient Survey recently discovered that the Class 0 protostar HOPS 358 decreased in 350 GHz continuum brightness by ∼25% over the course of 4 yr before brightening again for the next 4. The JCMT light curve can be fit by a long-timescale dip lasting roughly 8 yr. A shorter-timescale periodicity is also apparent with a period of 1.75 yr and a small 3% amplitude. NEOWISE monitoring reveals that the mid-infrared wavelength brightness of HOPS 358 follows a similar long-term pattern in time. Here, we present a study of nine epochs of Atacama Large Millimeter/submillimeter Array (ALMA) observations of HOPS 358 taken over the course of the decline and subsequent rise in brightness seen with the JCMT to test whether the variation seen on ∼15'' scales, covering both disk and envelope, is also observed on smaller, <1'' scales that primarily probe HOPS 358's protostellar disk. We detect both HOPS 358 and its southern companion, HOPS 358B, in our ALMA observations and find that at least one of the two is varying. Assuming that HOPS 358 is the variable, the light curve has the same shape as that found by the JCMT. Additionally, our high-resolution ALMA imaging of HOPS 358 reveals that the disk is warped, with a 16° warp at a disk radius of 35 au, about halfway through the extent of the disk. The physical origin of the warp and how it relates to the variability seen toward HOPS 358, however, remain unclear.}, archive = {J_ApJ}, author = {Patrick D. Sheehan and Doug Johnstone and Carlos Contreras Peña and Seonjae Lee and Gregory Herczeg and Jeong-Eun Lee and Steve Mairs and John J. Tobin and Hyeong-Sik Yun and The JCMT Transient Team}, doi = {10.3847/1538-4357/adaf9b}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {176}, shortjournal = {The Astrophys. J.}, title = {Submillimeter variability in the envelope and warped protostellar disk of the class 0 protostar HOPS 358}, volume = {982}, year = {2025}, }
• (2025). Aggressively dissipative dark dwarfs: The effects of atomic dark matter on the inner densities of isolated dwarf galaxies. ApJ, 982(2), 175. (www)

  @article{ , abstract = {We present the first suite of cosmological hydrodynamical zoom-in simulations of isolated dwarf galaxies for a dark sector that consists of cold dark matter and a strongly dissipative subcomponent. The simulations are implemented in GIZMO and include standard baryons following the FIRE-2 galaxy formation physics model. The dissipative dark matter is modeled as atomic dark matter (aDM), which forms a dark hydrogen gas that cools in direct analogy to the Standard Model. Our suite includes seven different simulations of ∼10 10 M ⊙ systems that vary over the aDM microphysics and the dwarf's evolutionary history. We identify a region of aDM parameter space where the cooling rate is aggressive and the resulting halo density profile is universal. In this regime, the aDM gas cools rapidly at high redshifts, and only a small fraction survives in the form of a central dark gas disk; the majority collapses centrally into collisionless dark "clumps," which are clusters of subresolution dark compact objects. These dark clumps rapidly equilibrate in the inner galaxy, resulting in an approximately isothermal distribution that can be modeled with a simple fitting function. Even when only a small fraction (∼5%) of the total dark matter is strongly dissipative, the central densities of classical dwarf galaxies can be enhanced by over an order of magnitude, providing a sharp prediction for observations.}, archive = {J_ApJ}, author = {Sandip Roy and Xuejian Shen and Jared Barron and Mariangela Lisanti and David Curtin and Norman Murray and Philip F. Hopkins}, doi = {10.3847/1538-4357/adb02b}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {175}, shortjournal = {The Astrophys. J.}, title = {Aggressively dissipative dark dwarfs: The effects of atomic dark matter on the inner densities of isolated dwarf galaxies}, volume = {982}, year = {2025}, }
• (2025). The core mass function across galactic environments. IV. the galactic center. ApJ, 982(2), 174. (www)

  @article{ , abstract = {The origin of the stellar initial mass function (IMF) and how it may vary with galactic environment is a matter of debate. Certain star formation theories involve a close connection between the IMF and the core mass function (CMF), so it is important to measure this CMF in a range of Milky Way locations. Here we study the CMF of three Galactic center clouds: G0.253+0.016 ("The Brick"), Sagittarius B2-Deep South field (Sgr B2-DS), and Sagittarius C (Sgr C). We use Atacama Large Millimeter/submillimeter Array 1 mm continuum images and identify cores as peaks in thermal dust emission via the dendrogram algorithm. We develop a completeness correction method via synthetic core insertion, utilizing a realistic mass-dependent size distribution. A power law \,dN/d\,\mathrm{log}M\propto {M}^{-\alpha } is fit to the CMFs >2 M ⊙ . The Brick has a Salpeter-like index α = 1.28 ± 0.09, while the other regions have shallower indices: Sgr C has α = 0.99 ± 0.06, and Sgr B2-DS has α = 0.70 ± 0.03. When smoothed to a common resolution, the differences between the Brick and the others increase as we obtain α = 1.36 ± 0.12, α = 0.66 ± 0.06, and α = 0.62 ± 0.04, respectively, for masses ≳3 M ⊙ . Furthermore, we analyze the spatial distribution and mass segregation of cores: Sgr C and Sgr B2-DS show signs of mass segregation, but the Brick does not. We compare our results to several other CMFs from different Galactic regions derived with the same methods. Finally, we discuss how our results may help define an evolutionary sequence of star cluster formation and be used to test star formation theories.}, archive = {J_ApJ}, author = {Alva V. I. Kinman and Maya A. Petkova and Jonathan C. Tan and Giuliana Cosentino and Yu Cheng}, doi = {10.3847/1538-4357/adb725}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {174}, shortjournal = {The Astrophys. J.}, title = {The core mass function across galactic environments. IV. the galactic center}, volume = {982}, year = {2025}, }
• (2025). Elemental abundances at coronal hole boundaries as a means to investigate interchange reconnection and the solar wind. ApJ, 982(2), 173. (www)

  @article{ , abstract = {The origin of the slow solar wind is not well understood, unlike the fast solar wind that originates from coronal holes. In situ elemental abundances of the slow solar wind suggest that it originates from initially closed field lines that become open. Coronal hole boundary regions are a potential source of slow solar wind, as open field lines there interact with the closed loops through interchange reconnection. Our primary aim is to quantify the role of interchange reconnection at the boundaries of coronal holes. To this end, we have measured the relative abundances of different elements at these boundaries. Reconnection is expected to modulate the relative abundances through the first ionization potential (FIP) effect. For our analysis, we used spectroscopic data from the EUV imaging spectrometer on board Hinode. To account for the temperature structure of the observed region, we computed the differential emission measure (DEM). Using the DEM, we were able to infer the ratio between coronal and photospheric abundances, known as the FIP bias. By examining the variation of the FIP bias moving from the coronal hole to the quiet Sun, we have been able to constrain models of interchange reconnection. The FIP bias variation in the boundary region around the coronal hole has an approximate width of 30–60 Mm, comparable to the size of supergranules. This boundary region is also a source of open flux into interplanetary space. We find that there could be an additional ∼37-71% open flux that originates from this boundary region.}, archive = {J_ApJ}, author = {Alexandros Koukras and Daniel W. Savin and Michael Hahn}, doi = {10.3847/1538-4357/adb7d4}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {173}, shortjournal = {The Astrophys. J.}, title = {Elemental abundances at coronal hole boundaries as a means to investigate interchange reconnection and the solar wind}, volume = {982}, year = {2025}, }
• (2025). Substellar landmass fraction and atmospheric circulation regimes of ultrashort-period rocky planets around white dwarfs. ApJ, 982(2), 172. (www)

  @article{ , abstract = {White-dwarf (WD) systems are attractive candidates for planet detection and follow-up transmission spectroscopy campaigns. However, the climate and habitability of terrestrial planets around WDs still remain largely elusive, and a central question lies in the width and extent of their habitable zones (HZs) and how their climates may be shaped by their stellar environments. A recently published study, using a 3D general circulation model (GCM), found a novel atmospheric circulation pattern for ultrarapid rotators around WDs. This "bat-rotation" regime features mean equatorial subrotation and a displacement of the surface's hottest regions from the equator toward the midlatitudes. Here, we used a GCM of reduced complexity to simulate a large range of landmass fraction (LMF) assumptions on these planets and examine the regimes in which these planets would exhibit the new dynamical regime. We find that as the dayside LMF approaches 80%, the bat-rotator features begin to diminish and the circulation behavior becomes more akin to the thermally driven direction circulation patterns observed around slowly rotating planets. Our results suggest that the introduction of different surface characteristics would drastically modify previous predictions of the atmospheres of ultrashort-period planets in the HZ of WD stars.}, archive = {J_ApJ}, author = {Cecilia Baker and Howard Chen and Luis Henry Quiroga-Nuñez}, doi = {10.3847/1538-4357/adb845}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {172}, shortjournal = {The Astrophys. J.}, title = {Substellar landmass fraction and atmospheric circulation regimes of ultrashort-period rocky planets around white dwarfs}, volume = {982}, year = {2025}, }
• (2025). DIISC-VI (COS-DIISC): Ultraviolet metal absorption relative to the h i disk of galaxies. ApJ, 982(2), 171. (www)

  @article{ , abstract = {As part of the Deciphering the Interplay between the Interstellar medium, Stars, and the Circumgalactic medium (DIISC) survey, we present the UV metal absorption features in the circumgalactic medium (CGM) near the H i gas disk (<4.5 R HI ) of 31 nearby galaxies through quasar absorption-line spectroscopy. Of the ions under study, Si iii λ 1206 was most frequently detected (18 of 31 sight lines), while C ii λ 1334 and Si ii λ 1260 were detected in 17 and 15 of 31 sight lines, respectively. Many components were consistent with photoionization equilibrium models; most of the cold and cool gas phase clouds were found to have lengths smaller than 2 kpc. Sight lines with smaller impact parameters ( ρ ) normalized by the galaxy's virial radius ( R vir ) and H i radius ( R HI ) tend to have more components and larger rest-frame equivalent widths ( W r ) than those that probe the CGM at larger radii. In particular, we find that the location of metals are better traced by ρ / R HI rather than the traditional ρ / R vir . Larger covering fractions are found closer to galaxies, with a radial decline that depends on the W r limit used. Our results provide new insights into the spatial distribution of metals around the H i disks of low-redshift galaxies.}, archive = {J_ApJ}, author = {Brad Koplitz and Sanchayeeta Borthakur and Timothy Heckman and Mansi Padave and Tyler McCabe and Jason Tumlinson and Andrew J. Fox and Guinevere Kauffmann}, doi = {10.3847/1538-4357/adb8ca}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {171}, shortjournal = {The Astrophys. J.}, title = {DIISC-VI (COS-DIISC): Ultraviolet metal absorption relative to the h i disk of galaxies}, volume = {982}, year = {2025}, }
• (2025). A 34 yr timing solution of the redback millisecond pulsar terzan 5A. ApJ, 982(2), 170. (www)

  @article{ , abstract = {We present a 34 yr timing solution of the redback pulsar system Terzan 5A (Ter5A). Ter5A, also known as B1744−24A or J1748−2446A, has a 11.56 ms pulse period, a ~0.1 M ⊙ dwarf companion star, and an orbital period of 1.82 hr. Ter5A displays highly variable eclipses and orbital perturbations. Using new timing techniques, we have determined a phase-connected timing solution for this system over 34 yr. This is the longest ever published for a redback pulsar. We find that the pulsar's spin variability is much larger than most globular cluster pulsars. In fact, of the nine redback pulsars with published or in-preparation long-term timing solutions, Ter5A is by far the noisiest. We see no evidence of strong correlations between orbital and spin variability of the pulsar. We also find that long-term astrometric timing measurements are likely too contaminated by this variability to be usable, and therefore they require careful short-term timing to determine reasonable positions. Finally, we measure an orbital period contraction of  −2.5(3) × 10 −13 , which is likely dominated by the general relativistic orbital decay of the system. The effects of the orbital variability due to the redback nature of the pulsar are not needed to explain the observed orbital period derivative, but they are constrained to less than ~30% of the observed value.}, archive = {J_ApJ}, author = {Alexandra C. Rosenthal and Scott M. Ransom and Kyle A. Corcoran and Megan E. DeCesar and Paulo C. C. Freire and Jason W. T. Hessels and Michael J. Keith and Ryan S. Lynch and Andrew Lyne and David J. Nice and Ingrid H. Stairs and Ben Stappers and Jay Strader and Stephen E. Thorsett and Ryan Urquhart}, doi = {10.3847/1538-4357/adb8cd}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {170}, shortjournal = {The Astrophys. J.}, title = {A 34 yr timing solution of the redback millisecond pulsar terzan 5A}, volume = {982}, year = {2025}, }
• (2025). What defines stationarity in space plasmas. ApJ, 982(2), 169. (www)

  @article{ , abstract = {Starting from the concept of entropy defect in thermodynamics, we construct the entropy formulation of space plasmas, and then use it to develop a measure of their stationarity. In particular, we show that the statistics of this entropy results in two findings that improve our understanding of stationary and nonstationary systems: (i) variations of Boltzmann−Gibbs (BG) entropy do not exceed twice the value of the thermodynamic kappa, the parameter that provides a measure of the entropy defect in both stationary and nonstationary states, while becoming the shape parameter that labels the kappa distributions in stationary states; and (ii) the ratio of the deviation of the BG entropy with kappa scales with the kappa deviation via a power law, while the respective exponent provides the stationarity deviation index (SDI), which measures the natural tendency of the system to depart from stationarity. We confirm the validity of these findings in three different heliospheric plasma data sets observed from three missions: (1) a solar energetic particle event, recorded by the Integrated Science Investigation of the Sun instrument on board the Parker Solar Probe; (2) near-Earth solar wind protons recorded by the Solar Wind Experiment instrument on board Wind; and (3) plasma protons in the heliosheath, the source of energetic neutral atoms recorded by Interstellar Boundary Explorer. The full strength and capability of the entropic deviation ratio and SDI can now be used by the space physics community for analyzing and characterizing the stationarity of space plasmas, as well as other researchers for analyzing any other correlated systems.}, archive = {J_ApJ}, author = {G. Livadiotis and D. J. McComas}, doi = {10.3847/1538-4357/adb8d2}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {169}, shortjournal = {The Astrophys. J.}, title = {What defines stationarity in space plasmas}, volume = {982}, year = {2025}, }
• (2025). Exploring unusual high-frequency eclipses in MSP j1908+2105. ApJ, 982(2), 168. (www)

  @article{ , abstract = {This paper presents a comprehensive study of the eclipse properties of the spider millisecond pulsar (MSP) J1908+2105, using wide-band observations from the uGMRT and Parkes UWL. For the first time, we observed that this pulsar exhibits extended eclipses up to 4 GHz, the highest frequency band of the Parkes Ultra-Wideband, making it one of only three MSPs known to have such high-frequency eclipses. This study reveals synchrotron absorption as the primary eclipse mechanism for J1908+2105. We present modeling of synchrotron optical depth with various possible combinations of the parameters to explain the observed eclipsing in this as well as other spider MSPs. Observed eclipses at unusually high frequencies for J1908+2105 significantly aided in constraining the magnetic field and electron column density in the eclipse medium while modeling the synchrotron optical depth. Combining our findings with data from other MSPs in the literature, for the first time we note that a higher cutoff frequency of eclipsing, particularly above 1 GHz, is consistently associated with a higher electron column density (>10 17 cm −2 ) in the eclipse medium. Additionally, we present the first evidence of lensing effects near eclipse boundaries in this MSP, leading to significant magnification of radio emissions. The orbital-phase-resolved polarization analysis presented in this paper further indicates variation in rotation measure and consequently stronger magnetic fields in the eclipse region.}, archive = {J_ApJ}, author = {Ankita Ghosh and Bhaswati Bhattacharyya and Sangita Kumari and Simon Johnston and Patrick Weltevrede and Jayanta Roy}, doi = {10.3847/1538-4357/adb8e0}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {168}, shortjournal = {The Astrophys. J.}, title = {Exploring unusual high-frequency eclipses in MSP j1908+2105}, volume = {982}, year = {2025}, }
• (2025). Disentangling γ − β: The fourth-order velocity moments based on spherical jeans analysis. ApJ, 982(2), 167. (www)

  @article{ , abstract = {Distinguishing a core and a cusp within dark matter halos is complexified by the existence of mass-anisotropy degeneracy, where various combinations of velocity anisotropy ( β ) and inner density slope ( γ ) yield similar observational signatures. We construct a dynamical model that incorporates the fourth-order velocity moments to alleviate this challenge. The inclusion of the fourth-order velocity moments enables a star's line-of-sight velocity distribution (LOSVD) to be flexible. This flexible LOSVD can range from a thin-tailed to a heavy-tailed distribution that is inaccessible if only the second-order moments are considered. We test the model on four mock galaxies having isotropic orbits, β = 0: two resembling dwarf spheroidal (dSph) galaxies and two resembling ultrafaint dwarfs (UFDs) in terms of velocity dispersion. Each category includes one galaxy with a cuspy Navarro–Frenk–White (NFW) profile and one with a cored density profile. The results show that a ratio of the global velocity dispersion to velocity error, σ los,global / δv los ≳ 4, is crucial to avoid systematic biases arising from the strong sensitivity of fourth-order moments to the LOSVD tails. In cases where this velocity ratio condition is met, our model reliably recovers γ in dSph mock galaxies, with the true value recovered within ∼1 σ , and strongly excludes a cuspy NFW profile for the cored dSph mock galaxy. However, recovering the density profiles of UFDs remains challenging due to their intrinsically low velocity dispersions.}, archive = {J_ApJ}, author = {Dafa Wardana and Masashi Chiba and Kohei Hayashi}, doi = {10.3847/1538-4357/adb8e4}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {167}, shortjournal = {The Astrophys. J.}, title = {Disentangling γ − β: The fourth-order velocity moments based on spherical jeans analysis}, volume = {982}, year = {2025}, }
• (2025). Velocity structure of circumstellar environment around class 0/I protostars: Uncertainty in the protostellar mass estimation using circumstellar velocities. ApJ, 982(2), 166. (www)

  @article{ , abstract = {Recent high-resolution observations have enabled detailed investigations of the circumstellar environments around Class 0/I protostars. Several studies have reported that the infall velocity of the envelope is a few times smaller than the freefall velocity inferred from protostellar masses estimated via the observed rotational velocity of their Keplerian disks. To explore the physical origins of the slow infall, we perform a set of three-dimensional resistive magnetohydrodynamic simulations of the star formation process, extending to 10 5 yr after protostar formation. Our simulations show that the infall velocity decreases markedly at the outer edge of the pseudodisk (at radii of ∼100–1000 au) and is much slower than the expected freefall velocity. The degree of this reduction depends on (1) the initial magnetic field strength, (2) the alignment between the initial field and the rotation axis, and (3) the evolutionary stage of the system. Across our parameter space, the ratio of the infall velocity to the freefall velocity is as small as 0.2–0.5, which is consistent with the observations. We further examine the reliability of protostellar mass estimates derived from infall and rotational velocities. While the mass derived from disk rotation closely matches the true value, deviation by a factor of 0.3–2 is found for the estimates using the infall velocity; it is underestimated due to slow infall, but could also be overestimated due to the contribution of disk mass. These findings underscore the critical role of magnetic fields in shaping star formation dynamics and highlight the uncertainties associated with protostellar mass estimates.}, archive = {J_ApJ}, author = {Shingo Hirano and Yuri Aikawa and Masahiro N. Machida}, doi = {10.3847/1538-4357/adb96f}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {166}, shortjournal = {The Astrophys. J.}, title = {Velocity structure of circumstellar environment around class 0/I protostars: Uncertainty in the protostellar mass estimation using circumstellar velocities}, volume = {982}, year = {2025}, }
• (2025). The gaia parallax discrepancy for the cluster pismis 19 and separating δ scutis from cepheids. ApJ, 982(2), 165. (www)

  @article{ , abstract = {Pre-Gaia distances for the open cluster Pismis 19 disagree with Gaia parallaxes. A Two Micron All Sky Survey (2MASS) JK s red clump distance was therefore established for Pismis 19 (2.90 ± 0.15 kpc), which reaffirms that zero-point corrections for Gaia are required. OGLE GD-CEP-1864 is confirmed as a member of Pismis 19 on the basis of DR3 proper motions and its 2MASS+Vista Variables in the Vía Láctea color–magnitude position near the tip of the turnoff. That 0.3 day variable star is likely a δ Scuti rather than a classical Cepheid. The case revealed a pertinent criterion to segregate those two populations in tandem with the break in the Wesenheit Leavitt Law (≃0.5 day). Just shortward of that period discontinuity are δ Scutis, whereas beyond the break lie first overtone classical Cepheids mostly observed beyond the first crossing of the instability strip.}, archive = {J_ApJ}, author = {Daniel Majaess and Charles J. Bonatto and David G. Turner and Roberto K. Saito and Dante Minniti and Christian Moni Bidin and Danilo González-Díaz and Javier Alonso-Garcia and Giuseppe Bono and Vittorio F. Braga and Maria G. Navarro and Giovanni Carraro and Matias Gomez}, doi = {10.3847/1538-4357/adb9e4}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {165}, shortjournal = {The Astrophys. J.}, title = {The gaia parallax discrepancy for the cluster pismis 19 and separating δ scutis from cepheids}, volume = {982}, year = {2025}, }
• (2025). Hyperneutron stars from an ab initio calculation. ApJ, 982(2), 164. (www)

  @article{ , abstract = {The equation of state (EOS) of neutron matter plays a decisive role in understanding the neutron star properties and the gravitational waves from neutron star mergers. At sufficient densities, the appearance of hyperons generally softens the EOS, leading to a reduction in the maximum mass of neutron stars well below the observed values of about 2 M ⊙ . Even though repulsive three-body forces are known to solve this so-called "hyperon puzzle," so far performing ab initio calculations with a substantial number of hyperons for neutron star properties has remained elusive. Starting from the newly developed auxiliary field quantum Monte Carlo algorithm to simulate hyperneutron matter without any sign oscillations, we derive three distinct EOSs by employing the state-of-the-art nuclear lattice effective field theory. We include N Λ, ΛΛ two-body forces, NN Λ, and N ΛΛ three-body forces. Consequently, we determine essential astrophysical quantities such as the neutron star mass, radius, tidal deformability, and universal I –Love– Q relation. The maximum mass, radius, and tidal deformability of a 1.4 M ⊙ neutron star are predicted to be 2.17(1)(1) M ⊙ , R 1.4 M ⊙ = 13.10(1)(7) km, and {{\rm{\Lambda }}}_{1.4{M}_{\odot }}=597(5)(18) , respectively, based on our most realistic EOS. These predictions are in good agreement with the latest astrophysical constraints derived from observations of massive neutron stars, gravitational waves, and joint mass–radius measurements. In addition, for the first time in ab initio calculations, we investigate both nonrotating and rotating neutron star configurations. The results indicate that the impact of rotational dynamics on the maximum mass is small, regardless of whether hyperons are present in the EOS or not.}, archive = {J_ApJ}, author = {Hui Tong and Serdar Elhatisari and Ulf-G. Meißner​}, doi = {10.3847/1538-4357/adba47}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {164}, shortjournal = {The Astrophys. J.}, title = {Hyperneutron stars from an ab initio calculation}, volume = {982}, year = {2025}, }
• (2025). VLASS tidal disruption events with optical flares. i. the sample and a comparison to optically selected TDEs. ApJ, 982(2), 163. (www)

  @article{ , abstract = {In this work, we use the Jansky Very Large Array Sky Survey to compile the first sample of six radio-selected tidal disruption events (TDEs) with transient optical counterparts. While we still lack the statistics to do detailed population studies of radio-selected TDEs, we use these events to suggest trends in host galaxy and optical light-curve properties that may correlate with the presence of radio emission and hence can inform optically selected TDE radio follow-up campaigns. We find tentative trends that radio-selected TDEs tend to have faint and cool optical flares, as well as host galaxies with low supermassive black hole masses, although larger samples are required to establish these trends as statistically significant. Our radio-selected TDEs also tend to have more energetic, larger radio-emitting regions than radio-detected, optically selected TDEs. We consider possible explanations for these trends, including by invoking super-Eddington accretion and enhanced circumnuclear media. Finally, we constrain the radio-emitting TDE rate to be ≳10 Gpc −3 yr −1 .}, archive = {J_ApJ}, author = {Jean J. Somalwar and Vikram Ravi and Dillon Z. Dong and Erica Hammerstein and Gregg Hallinan and Casey Law and Jessie Miller and Steven T. Myers and Yuhan Yao and Richard Dekany and Matthew Graham and Steven L. Groom and Josiah Purdum and Avery Wold}, doi = {10.3847/1538-4357/adba4f}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {163}, shortjournal = {The Astrophys. J.}, title = {VLASS tidal disruption events with optical flares. i. the sample and a comparison to optically selected TDEs}, volume = {982}, year = {2025}, }
• (2025). Laboratory detection of the methoxymethyl radical, CH3OCH2, using faraday rotation and chirped-pulse techniques in the (Sub)millimeter wave range. ApJ, 982(2), 162. (www)

  @article{ , abstract = {Modeling the abundance of interstellar complex organic molecules in space is a major challenge for astrophysicists. The relative roles of gas-phase and grain-surface processes in the formation and destruction of such large molecules remain unclear. Methyl formate (CH 3 OCHO, MF) and dimethyl ether (CH 3 OCH 3 , DME) species have been detected at relatively high abundances in both warm and cold objects of the interstellar medium (ISM), challenging an initial hypothesis favoring grain-surface processes for their formation. In this context, the methoxymethyl radical (CH 3 OCH 2 , RDME) has been proposed as a key species linking the abundances of MF and DME in the gas phase. Its detection may provide crucial information to disentangle and quantify the different processes involved in the formation and destruction of MF and DME. To support the search for RDME in space, we present the laboratory detection of its pure rotational spectrum in the vibronic ground state. Special care was taken to measure the frequencies of transitions expected to be intense under cold interstellar conditions. In total, we assigned and fitted 1007 transitions of the RDME with {N}^{{\prime} } and {K}_{a}^{{\prime} } values up to 34 and 5, respectively. A reliable spectral catalog has been generated using the spectroscopic parameters derived from the fit and can be used confidently for future searches of the RDME radical in the ISM.}, archive = {J_ApJ}, author = {Rosemonde Chahbazian and Marie-Aline Martin-Drumel and Olivier Pirali}, doi = {10.3847/1538-4357/adba5c}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {162}, shortjournal = {The Astrophys. J.}, title = {Laboratory detection of the methoxymethyl radical, CH3OCH2, using faraday rotation and chirped-pulse techniques in the (Sub)millimeter wave range}, volume = {982}, year = {2025}, }
• (2025). A high-accuracy alignment approach for solar images of different wavelengths. ApJ, 982(2), 161. (www)

  @article{ , abstract = {Image alignment plays a crucial role in solar physics research, primarily involving translation, rotation, and scaling. The different wavelength images of the chromosphere and transition region have structural complexity and differences in similarity, which poses a challenge to their alignment. Therefore, a novel alignment approach based on dense optical flow (OF) and the RANSAC algorithm is proposed in this paper. It takes the OF vectors of similar regions between images to be used as feature points for matching. Then, it calculates scaling, rotation, and translation. The study selects three wavelengths for two groups of alignment experiments: the 304 Å of the Atmospheric Imaging Assembly (AIA), the 1216 Å of the Solar Disk Imager (SDI), and the 465 Å of the Solar Upper Transition Region Imager (SUTRI). Two methods are used to evaluate alignment accuracy: Monte Carlo simulation and Uncertainty Analysis Based on the Jacobian Matrix. The evaluation results indicate that this approach achieves subpixel accuracy in the alignment of AIA 304 Å and SDI 1216 Å, while demonstrating higher accuracy in the alignment of AIA 304 Å and SUTRI 465 Å, which have greater similarity.}, archive = {J_ApJ}, author = {Yun Wang and Kaifan Ji and Zhenyu Jin and Hui Liu}, doi = {10.3847/1538-4357/adbaec}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {161}, shortjournal = {The Astrophys. J.}, title = {A high-accuracy alignment approach for solar images of different wavelengths}, volume = {982}, year = {2025}, }
• (2025). The radial variation of suprathermal particles in stream interaction regions: Comparisons between solar orbiter, ACE, and STEREO-A. ApJ, 982(2), 160. (www)

  @article{ , abstract = {With the launch of Solar Orbiter, the intensity and composition of suprathermal particles have been sampled within the inner heliosphere at distances between ∼0.3 and 1 au. This includes a multitude of observations of suprathermal ions associated with stream interaction regions (SIRs) measured by the Solar Orbiter Energetic Particle Detector, with corresponding observations at 1 au from the Ultra-Low-Energy Isotope Spectrometer on the Advanced Composition Explorer mission and the Suprathermal Ion Telescope on the Solar-Terrestrial Relations Observatory-Ahead spacecraft. Comparing observations between these spacecraft enables a statistical view of the radial variations of SIR-associated suprathermal particles, allowing for greater insight into energetic particle transport within the inner heliosphere. The observed radial trends agree well with that found by M. A. I. Van Hollebeke et al. but indicate a smaller modulation of particle spectra due to transport than predicted by L. A. Fisk & M. A. Lee. This possible difference between the observed empirical relationship and theoretical formulation may arise from either sub-Parker spiral topology in the rarefaction region and/or a velocity-dependent, rather than rigidity or explicit species-dependent, diffusion treatment in L. A. Fisk & M. A. Lee.}, archive = {J_ApJ}, author = {Robert C. Allen and George C. Ho and Glenn M. Mason and Athanasios Kouloumvakos and Gang Li and Rachael J. Filwett and Maher Dayeh and Malik H. Walker and Sarah K. Vines and Robert F. Wimmer-Schweingruber and Javier Rodriguez-Pacheco}, doi = {10.3847/1538-4357/adbe37}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {160}, shortjournal = {The Astrophys. J.}, title = {The radial variation of suprathermal particles in stream interaction regions: Comparisons between solar orbiter, ACE, and STEREO-A}, volume = {982}, year = {2025}, }
• (2025). Thermal phase curves in hot gas giant exoplanets exhibit a complex dependence on planetary properties. ApJ, 982(2), 159. (www)

  @article{ , abstract = {We present a catalog of uniformly processed 3.6 μ m and 4.5 μ m band exoplanet thermal phase curves based on Infrared Array Camera observations obtained from the Spitzer Heritage Archive. The catalog includes phase curve measurements for 34 planets, 16 of which contain full orbit coverage and have detectable secondary eclipses in both channels. The data are processed in the EXCALIBUR pipeline using a uniform analysis consisting of aperture photometry and modeling of instrument effects along with the exoplanet signal. Nearest-neighbor regression with a Gaussian kernel is used to correct for instrumental systematics correlated to the star's centroid position and shape in conjunction with a novel test to avoid overfitting. These methods may have utility in addressing subpixel gain variations present in modern infrared detectors. We analyze the 3.6 μ m and 4.5 μ m phase curve properties and find a strong wavelength-dependent difference in how the properties correlate with physical parameters as well as evidence that the phase curve properties are determined by multiple physical parameters. We suggest that differences between the 3.6 μ m and 4.5 μ m phase curve properties are due to 3.6 μ m observations probing regions of the atmosphere which could include a cloud layer. Taken together, the observed phase curve behavior suggests that different physical processes are responsible for establishing the thermal phase curve at different pressures, which are probed by different wavelengths, and that further 3D Global Circulation Model modeling is required to investigate the reason for this complex dependence on planetary properties.}, archive = {J_ApJ}, author = {Mark R. Swain and Kyle A. Pearson and Thaddeus D. Komacek and Geoffrey Bryden and Emeline Fromont and Gautam Vasisht and Gael Roudier and Robert T. Zellem}, doi = {10.3847/1538-4357/adb835}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {159}, shortjournal = {The Astrophys. J.}, title = {Thermal phase curves in hot gas giant exoplanets exhibit a complex dependence on planetary properties}, volume = {982}, year = {2025}, }
• (2025). Bias-corrected fast radio burst population and spectra using CHIME injection data. ApJ, 982(2), 158. (www)

  @article{ , abstract = {Fast radio bursts (FRBs), a class of millisecond-scale, highly energetic phenomena with unknown progenitors and radiation mechanisms, require proper statistical analysis as a key method for uncovering their mysteries. In this research, we build on the bias correction method using pulse injections for the first Canadian Hydrogen Intensity Mapping Experiment/FRB catalog, to include correlations between properties and to analyze the FRB population spectrum. This model includes six FRB properties: dispersion measure (DM), pulse width, scattering timescale, spectral index, spectral running, and fluence. By applying the multidimensional weight function calculated by the model, we update the corrected distributions, suggesting that more low-DM, short- and long-width, and short-scattering timescale events may exist. Using one-off events and the first bursts from repeaters, the derived intrinsic population spectrum has a best-fit power law of F ( ν ) ∝ ν α , where α = −2.29 ± 0.29. This confirms previous indications that FRBs are brighter or more numerous at low frequencies. Analyzing nonrepeaters only, we find α = −2.50 ± 0.43, while including all bursts from repeaters produces α = −1.91 ± 0.20. This hints that active repeaters, low-rate repeaters, and nonrepeaters may have different progenitors, mechanisms, or evolutionary stages.}, archive = {J_ApJ}, author = {Xiang-han Cui and Clancy. W. James and Di Li and Cheng-min Zhang}, doi = {10.3847/1538-4357/adbbcb}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {158}, shortjournal = {The Astrophys. J.}, title = {Bias-corrected fast radio burst population and spectra using CHIME injection data}, volume = {982}, year = {2025}, }
• (2025). Extracting the temperature analytically in hydrodynamics simulations with gas and radiation pressure. ApJ, 982(2), 157. (www)

  @article{ , abstract = {Numerical hydrodynamics simulations of gases dominated by ideal, nondegenerate matter pressure and thermal radiation pressure in equilibrium entail finding the temperature as part of the evolution. Since the temperature is not typically a variable that is evolved independently, it must be extracted from the evolved variables (e.g., the rest-mass density and specific internal energy). This extraction requires solving a quartic equation, which, in many applications, is done numerically using an iterative root-finding method. Here we show instead how the equation can be solved analytically and provide explicit expressions for the solution. We also derive Taylor expansions in limiting regimes and discuss the respective advantages and disadvantages of the iterative versus analytic approaches to solving the quartic.}, archive = {J_ApJ}, author = {Thomas W. Baumgarte and Stuart L. Shapiro}, doi = {10.3847/1538-4357/adbd10}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {157}, shortjournal = {The Astrophys. J.}, title = {Extracting the temperature analytically in hydrodynamics simulations with gas and radiation pressure}, volume = {982}, year = {2025}, }
• (2025). Unraveling visible spectra of S-type stars: The f3Δ–a3Δ (α system) and e3Π–a3Δ (β system) band systems of ZrO. ApJ, 982(2), 156. (www)

  @article{ , abstract = {ZrO has many low-lying states, and its spectra are essential for the characterization of S-type stars. A high-resolution emission spectrum recorded with a Fourier transform spectrometer at the National Solar Observatory is used for the analysis. The 0–0 and 1–0 bands of the f 3 Δ–a 3 Δ system ( α system) and the 0–0 band of the e 3 Π–a 3 Δ system ( β system) have been rotationally analyzed using the modern spectral fitting program PGOPHER. New ab initio calculations of transition dipole moments have been performed to determine the band strengths. These band strengths are used to produce line lists that are suitable for the simulation of stellar spectra.}, archive = {J_ApJ}, author = {Manish Bhusal and Peter F Bernath and Jacques Liévin}, doi = {10.3847/1538-4357/adbd3f}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {156}, shortjournal = {The Astrophys. J.}, title = {Unraveling visible spectra of S-type stars: The f3Δ–a3Δ (α system) and e3Π–a3Δ (β system) band systems of ZrO}, volume = {982}, year = {2025}, }
• (2025). Tracking the chemical evolution of hydrocarbons through carbon grain supply in protoplanetary disks. ApJ, 982(2), 155. (www)

  @article{ , abstract = {The gas present in planet-forming disks typically exhibits strong emission features of abundant carbon and oxygen molecular carriers. In some instances, protoplanetary disks show an elevated C/O ratio above interstellar values, which leads to a rich hydrocarbon chemistry evidenced in the mid-infrared spectra. The origin of this strengthened C/O ratio may stem from the release of less complex hydrocarbons from the chemical processing of carbonaceous grains. We have explored a set of 42 single-cell models in which we match the physical conditions to the inner regions of planet-forming disks, while varying the C/O ratio by exploring different levels of CH 4 , C, H 2 O, and CO to the gas-phase chemistry, which we evaluate in both the cosmic/X-ray- and UV-driven limit. We find that the carbon-bearing species in our models exhibit high dependencies on the driver of the chemistry, where both CO and long chain hydrocarbons act as carbon sinks in the cosmic/X-ray-driven chemistry limit, while the vast majority ends up in atomic carbon and CO in the UV-driven limit. We also find moderate dependencies upon the C/O ratio, where this and the ionization rate/UV field determines the point of peak production of a species, as well as its equilibrium abundance. We also find that the production of several hydrocarbons, specifically C 2 H 2 , is strongly dependent up to an order of magnitude on the initial water abundance. We finally find that in the X-ray-driven limit, both CH 4 and C serve as highly transient donor species to the carbon chemistry.}, archive = {J_ApJ}, author = {Eshan Raul and Felipe Alarcón and Edwin A. Bergin}, doi = {10.3847/1538-4357/adaeae}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {155}, shortjournal = {The Astrophys. J.}, title = {Tracking the chemical evolution of hydrocarbons through carbon grain supply in protoplanetary disks}, volume = {982}, year = {2025}, }
• (2025). Polarization properties of 28 repeating fast radio burst sources with CHIME/FRB. ApJ, 982(2), 154. (www)

  @article{ , abstract = {As part of the Canadian Hydrogen Intensity Mapping Experiment Fast Radio Burst (CHIME/FRB) project, we report 41 new rotation measures (RMs) from 20 repeating fast radio bursts (FRBs) obtained between 2019 and 2023 for which no previous RM was determined. We also report 22 additional RM measurements for eight further repeating FRBs. We observe temporal RM variations in practically all repeating FRBs. Repeaters appear to be separated into two categories: those with dynamic and those with stable RM environments, differentiated by the ratios of RM standard deviations to the averaged RM magnitudes. Sources from stable RM environments likely have small RM contributions from the interstellar medium of their host galaxies, whereas sources from dynamic RM environments share some similarities with Galactic pulsars in eclipsing binaries but appear distinct from solitary pulsars in the Galactic centre. We observe a new stochastic, secular, and again stochastic trend in the temporal RM variation of FRB 20180916B, which does not support binary orbit modulation being its cause. We highlight two more repeaters that show RM sign change, namely FRBs 20290929C and 20190303A. We perform an updated comparison of polarization properties between repeating and nonrepeating FRBs, which show a marginal dichotomy in their distribution of electron-density-weighted parallel-component line-of-sight magnetic fields.}, archive = {J_ApJ}, author = {Cherry Ng and Ayush Pandhi and Ryan Mckinven and Alice P. Curtin and Kaitlyn Shin and Emmanuel Fonseca and B. M. Gaensler and Dylan L. Jow and Victoria Kaspi and Dongzi Li and Robert Main and Kiyoshi W. Masui and Daniele Michilli and Kenzie Nimmo and Ziggy Pleunis and Paul Scholz and Ingrid Stairs and Mohit Bhardwaj and Charanjot Brar and Tomas Cassanelli and Ronniy C. Joseph and Aaron B. Pearlman and Masoud Rafiei-Ravandi and Kendrick Smith}, doi = {10.3847/1538-4357/adb0bc}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {154}, shortjournal = {The Astrophys. J.}, title = {Polarization properties of 28 repeating fast radio burst sources with CHIME/FRB}, volume = {982}, year = {2025}, }
• (2025). Accelerated emergence of evolved galaxies in early overdensities at z ∼ 5.7. ApJ, 982(2), 153. (www)

  @article{ , abstract = {We report the identification of two galaxy overdensities at z ∼ 5.7 in the sightline of the galaxy cluster A2744. These overdensities consist of 25 and 17 member galaxies, spectroscopically confirmed with JWST NIRSpec micro-shutter assembly and NIRCam/WFSS. Each overdensity has a total stellar mass of ∼2 × 10 10 M ⊙ and a star formation rate of ∼200 M ⊙ yr −1 within a central region of radius R = 2 Mpc (physical). The sensitive PRISM spectra allow us to identify six galaxies that show weak H α + [N ii ] emissions within the overdensities (25% ± 7%), whereas the fraction of such galaxies is found significantly lower (6% ± 2%) in field samples of the equivalent redshift range. These weak emission line galaxies, dubbed as wELGs, exhibit a strong continuum break at the 4000 Å rest frame, a characteristic feature of evolved stellar populations. The high observed fraction of wELGs in the two overdensities is consistent with the idea that high-density environments are an ideal site where galaxies can accelerate their evolutionary pace compared to field analogs. Our study pinpoints an early onset of environmental effects, already important within one billion years after the Big Bang, and provides a complementary perspective on the emergence of quenched, massive galaxies at lower redshifts. Potential contributions from black hole accretion feedback to the reduction in star formation activity are discussed, but the connection to the local environments remains unclear.}, archive = {J_ApJ}, author = {Takahiro Morishita and Zhaoran Liu and Massimo Stiavelli and Tommaso Treu and Michele Trenti and Nima Chartab and Guido Roberts-Borsani and Benedetta Vulcani and Pietro Bergamini and Marco Castellano and Claudio Grillo}, doi = {10.3847/1538-4357/adb30f}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {153}, shortjournal = {The Astrophys. J.}, title = {Accelerated emergence of evolved galaxies in early overdensities at z ∼ 5.7}, volume = {982}, year = {2025}, }
• (2025). Insights into solar wind flow speeds from the coronal radio occultation experiment: Findings from the indian mars orbiter mission. ApJ, 982(2), 152. (www)

  @article{ , abstract = {Using data collected by the Indian Mars Orbiter Mission (MOM) in 2021 October, we investigated coronal regions of the Sun by analyzing the Doppler spectral width of radio signals to estimate solar wind velocity. A simplified equation is introduced to directly relate these two parameters. The study focuses on observations conducted from 2021 October 2 to October 14, a relatively quiet phase of solar cycle 25. The analysis targeted the coronal region within heliocentric distances of 5–8 R ⊙ , near the ecliptic plane. In this region, solar wind velocities ranged from 100 to 150 km s −1 , while electron densities were on the order of 10 10 m −3 . We also compared our results with electron density observations and models derived from previous studies. Though the decrease in the electron densities with respect to increasing heliocentric distance matches quite well with the theoretical models, MOM estimates fall at the lower edge of the distribution. This difference may be attributed to the prolonged weak solar activity during the MOM observations, in contrast to prior studies conducted during periods of comparatively higher solar activity in earlier solar cycles.}, archive = {J_ApJ}, author = {Keshav Aggarwal and R. K. Choudhary and Abhirup Datta and Roopa M. V. and Bijoy K. Dai}, doi = {10.3847/1538-4357/adb627}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {152}, shortjournal = {The Astrophys. J.}, title = {Insights into solar wind flow speeds from the coronal radio occultation experiment: Findings from the indian mars orbiter mission}, volume = {982}, year = {2025}, }
• (2025). FEASTS combined with interferometry. III. the low column density h i around m51 and possibility of turbulent-mixing gas accretion. ApJ, 982(2), 151. (www)

  @article{ , abstract = {With a new joint-deconvolution pipeline, we combine the single-dish and interferometric atomic hydrogen (H i ) data of M51 observed by the Five-hundred-meter Aperture Spherical radio Telescope (FAST) (FEASTS program) and the Very Large Array (VLA) (THINGS). The product data cube has a typical line width of 13 km s −1 and a 2 σ line-of-sight (LOS) sensitivity of H i column density N H i ∼ 3.2 × 18 cm −2 at a spatial resolution of ∼18'' (∼0.7 kpc). Among the H i detected LOSs extending to ∼50 kpc, ∼89% consist of diffuse H i only, which is missed by previous VLA observations. The distribution of dense H i is reproduced by previous hydrodynamical simulations of this system, but the diffuse component is not, likely due to unresolved physics related to the interaction between the circumgalactic and interstellar media. With simple models, we find that these low N H i structures could survive the background ultraviolet photoionization, but are susceptible to the thermal evaporation. We find a positive correlation between LOS velocity dispersion ( σ v ) and N H i with a logarithmic index of ∼0.5. Based on existing turbulent mixing layer (TML) theories and simulations, we propose a scenario of hot gas cooling and accreting onto the disk through a TML, which could reproduce the observed power index of ∼0.5. We estimate the related cooling and accretion rates to be roughly one-third to two-thirds of the star formation rate. A typical column density of diffuse H i (∼10 19 cm −2 ) can be accreted within 300 Myr, the interaction timescale previously estimated for the system. Such a gas accretion channel has been overlooked before, and may be important for gas-rich interacting systems and for high-redshift galaxy evolution.}, archive = {J_ApJ}, author = {Xuchen Lin and Jing Wang and Lister Staveley-Smith and Suoqing Ji and Dong Yang and Xinkai Chen and Fabian Walter and Hsiao-Wen Chen and Luis C. Ho and Peng Jiang and Nir Mandelker and Se-Heon Oh and Bo Peng and Céline Péroux and Zhijie Qu and Q. Daniel Wang}, doi = {10.3847/1538-4357/adb718}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {151}, shortjournal = {The Astrophys. J.}, title = {FEASTS combined with interferometry. III. the low column density h i around m51 and possibility of turbulent-mixing gas accretion}, volume = {982}, year = {2025}, }
• (2025). AT2021aeuk: A repeating partial tidal disruption event candidate in a narrow-line seyfert 1 galaxy. ApJ, 982(2), 150. (www)

  @article{ , abstract = {A black hole (BH) can tear apart a star that ventures within its tidal radius, producing a luminous flare as the stellar debris falls back, known as a tidal disruption event (TDE). While TDEs in quiescent galaxies are relatively well understood, identifying TDEs in active galactic nuclei (AGNs) still remains a significant challenge. We present the discovery of AT2021aeuk, a transient exhibiting dual flares within around 3 yr in a narrow-line Seyfert 1 galaxy. Multiwavelength observations triggered during the second flare in 2023 revealed an extraordinary X-ray V-shaped light curve, strongly anticorrelated with the optical light curve and accompanied by a lag of ∼40 days. This behavior is inconsistent with both supernova and pure AGN origins. In addition, a new broad component emerges in the Balmer lines during the second flare, showing a clear reverberation signal to the continuum variation. We propose that the dual flare may be linked to a repeating partial TDE (rpTDE), where the second flare results from a collision between the TDE stream and the inner accretion disk, triggering an optical flare while simultaneously partially destroying the X-ray corona. However, other mechanisms, such as a stellar-mass BH merger within an accretion disk, could produce similar phenomena, which we cannot entirely rule out. The Vera C. Rubin Observatory will be a powerful tool for further investigating the nature of such events in the future.}, archive = {J_ApJ}, author = {Jingbo Sun and Hengxiao Guo and Minfeng Gu and Ya-Ping Li and Yongjun Chen and D. González-Buitrago and Jian-Guo Wang and Sha-Sha Li and Hai-Cheng Feng and Dingrong Xiong and Yanan Wang and Qi Yuan and Jun-jie Jin and Wenda Zhang and Hongping Deng and Minghao Zhang}, doi = {10.3847/1538-4357/adb724}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {150}, shortjournal = {The Astrophys. J.}, title = {AT2021aeuk: A repeating partial tidal disruption event candidate in a narrow-line seyfert 1 galaxy}, volume = {982}, year = {2025}, }
• (2025). CORINOS. III. outflow shocked regions of the low-mass protostellar source IRAS 15398–3359 with JWST and ALMA. ApJ, 982(2), 149. (www)

  @article{ , abstract = {While molecular outflows have been studied in detail with radio interferometry, observations of the hotter gas in protostellar outflows at a comparable physical scale are often challenging. Combined with the Atacama Large Millimeter/submillimeter Array (ALMA), JWST allows us to investigate the cold and hot gas with unprecedented spatial resolution and sensitivity. We present a detailed comparison between the gas distributions probed with ALMA and JWST in the primary outflow of IRAS 15398−3359. At 2000 au scale, the southwestern outflow shows four shell structures in 5–10 μ m continuum, whereas the submillimeter H 2 CO emission traces two of the four shells closest to the protostar. Submillimeter emission from CS, CCH, c–C 3 H 2 , and CH 3 OH shows the same two shells, and the 12 CO emission covers most of the outflow region. SO and SiO only trace a condensation at the edge of the shell closest to the protostar. None of these lines observed with ALMA show the outermost shell. At 500 au scale, we find hot H 2 gas inside the outflow cavity with JWST. The derived temperature of H 2 is 1147 ± 198 K within a 0 \mathop{.}\limits^{^{\prime\prime} } 5 aperture at the protostar. The foreground mass column density of dust is (1.4–2.0) × 10 −3 g · cm −2 ( A V = 47–66 mag) in the outflow, using the dust model from J. C. Weingartner & B. T. Draine ( 2001 ). We also find an 8 ∘ difference between the directions toward the [Fe ii ] knot and the outermost shell in the MIRI image, which may be interpreted as the precession of the [Fe ii ] jet. The dynamical timescale of the [Fe ii ] knot is 10 yr, suggesting a current event.}, archive = {J_ApJ}, author = {Yuki Okoda and Yao-Lun Yang and Neal J. Evans II and Jaeyeong Kim and Mihwa Jin and Robin T. Garrod and Logan Francis and Doug Johnstone and Cecilia Ceccarelli and Claudio Codella and Claire J. Chandler and Satoshi Yamamoto and Nami Sakai}, doi = {10.3847/1538-4357/adb83f}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {149}, shortjournal = {The Astrophys. J.}, title = {CORINOS. III. outflow shocked regions of the low-mass protostellar source IRAS 15398–3359 with JWST and ALMA}, volume = {982}, year = {2025}, }
• (2025). The redshift evolution of the luminosity function of type II gamma-ray bursts. ApJ, 982(2), 148. (www)

  @article{ , abstract = {As of 2023 December, the Neil Gehrels Swift Observatory satellite has detected more than 1600 gamma-ray bursts (GRBs). We select 307 Type II GRBs for constructing the luminosity function (LF) based on the following criteria: (1) duration T 90 ≥ 2 s; (2) conformity with the Amati relation for Type II GRBs; and (3) peak flux P ≥ 1 photon cm −2 s −1 . We explore two general forms of the GRB LF: a broken power-law (BPL) LF and a triple power-law (TPL) LF. We consider three evolutionary scenarios: no evolution, luminosity evolution, and density evolution. We find that the no-evolution model can be excluded, while both the luminosity and density evolution models effectively account for the observations. This result is consistent with previous studies on long-duration GRBs (LGRBs). However, our Type II GRB sample favors a BPL LF, in contrast to the preference for a TPL function discovered for LGRBs.}, archive = {J_ApJ}, author = {Yan-Kun Qu and Zhong-Xiao Man and Yu-Peng Yang and Shuang-Xi Yi and Mei Du and Fa-yin Wang}, doi = {10.3847/1538-4357/adb849}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {148}, shortjournal = {The Astrophys. J.}, title = {The redshift evolution of the luminosity function of type II gamma-ray bursts}, volume = {982}, year = {2025}, }
• (2025). Formation of jet-driven forced reconnection region and associated plasma blobs in a prominence segment. ApJ, 982(2), 147. (www)

  @article{ , abstract = {We use data from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory to study the most likely formation of a forced reconnection region and associated plasma blobs, triggered by jetlike structures in a prominence segment. Around 05:44 UT on 2017 December 16th, hot jetlike structures lifted from a nearby active region and fell obliquely on one side of the prominence segment with velocities of ≈45–65 km s −1 . These eruptions compressed the boundaries of the prominence and flux rope, forming an elongated reconnection region with inflow velocities of 47–52 km s −1 and 36–49 km s −1 in the projected plane. A thin, elongated reconnection region was formed, with multiple magnetic plasma blobs propagating bidirectionally at velocities of 91–178 km s −1 . These dense blobs, associated with ongoing reconnection, may also be linked to the onset of Kelvin–Helmholtz (K-H) instability. The blobs are attributed to plasmoids, moving at slower speeds (91–178 km s −1 ) due to the high density in the prominence segment. The dimensionless reconnection rate varied from 0.57–0.28, 0.53–0.26, and 0.41–0.20, indicating reconnection rate enhancement and supporting the forced reconnection scenario. After reconnection, the prominence plasma heated to 6 MK, releasing significant thermal energy (≈5.4 × 10 27 erg), which drained cool prominence plasma and heated it to coronal temperatures. The ubiquity of jets and outflows in the solar atmosphere makes the aforementioned reconnection and possible coexistence of K-H instability potentially important for the magnetic energy release and heating in the solar atmosphere.}, archive = {J_ApJ}, author = {Sudheer K. Mishra and A. K. Srivastava and S. P. Rajaguru and P. Jelínek}, doi = {10.3847/1538-4357/adb8db}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {147}, shortjournal = {The Astrophys. J.}, title = {Formation of jet-driven forced reconnection region and associated plasma blobs in a prominence segment}, volume = {982}, year = {2025}, }
• (2025). Improved constraints on the faraday rotation toward eight fast radio bursts using dense grids of polarized radio galaxies. ApJ, 982(2), 146. (www)

  @article{ , abstract = {We present 2–4 GHz observations of polarized radio galaxies toward eight fast radio bursts (FRBs), producing grids of Faraday rotation measure (RM) sources with sky densities of 9–28 polarized sources per square degree. Using a Bayesian interpolation framework, we constrain Galactic RM fluctuations below ∼1 deg 2 angular scales around the FRB positions. Despite the positions of all eight FRBs being located far from the Galactic plane, we constrain previously unresolved small-scale Galactic RM structures around six of the eight FRBs. In two of these fields, we find potential changes in the sign of the Galactic RM that are not captured by previous, sparsely sampled RM grid observations. Our Galactic RM estimate toward the FRBs differs by a few radians per square meter up to ∼40 rad m −2 from the all-sky Galactic RM map of S. Hutschenreuter et al. Extrapolating our results to the known population of polarized FRB sources, we may be incorrectly interpreting the host galaxy RM for ∼30% of the FRB source population with current RM grid observations. Measuring small-scale Galactic RM variations is crucial for identifying FRBs in low-density and weakly magnetized environments, which in turn could serve as potent probes of cosmic magnetism. This framework of reconstructing continuous Galactic RM structure from RM grid observations can be readily applied to FRBs that fall within the sky coverage of upcoming large-sky radio polarization surveys of radio galaxies, such as the Very Large Array Sky Survey and the Polarization Sky Survey of the Universe's Magnetism.}, archive = {J_ApJ}, author = {Ayush Pandhi and B. M. Gaensler and Ziggy Pleunis and Sebastian Hutschenreuter and Casey Law and Ryan Mckinven and Shane P. O’Sullivan and Emily B. Petroff and Tessa Vernstrom}, doi = {10.3847/1538-4357/adb8e3}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {146}, shortjournal = {The Astrophys. J.}, title = {Improved constraints on the faraday rotation toward eight fast radio bursts using dense grids of polarized radio galaxies}, volume = {982}, year = {2025}, }
• (2025). High-energy jet emission from GRS 1758–258 and 1E 1740.7–2942 with INTEGRAL?. ApJ, 982(2), 145. (www)

  @article{ , abstract = {GRS 1758–258 and 1E 1740.7–2942 are two long-known persistent black hole binaries in the Galactic center region. Using the International Gamma-Ray Astrophysics Laboratory (INTEGRAL)'s extensive monitoring of the Galactic center and bulge, we studied their temporal and spectral evolutions in the 30–610 keV energy range from 2003 March through 2022 April with the Imager on Board INTEGRAL/INTEGRAL Soft Gamma-ray Imager gamma-ray telescope. Our analyses found that the sources typically had Comptonized spectra, though not always with the same parameters. The spectral states with more than 8 Ms of observation time show deviations from a Comptonized spectrum above ∼200 keV or a "hard tail" that extends up to at least 600 keV. The origin of this component remains debated, with the most popular scenarios being synchrotron emission from the jet or Comptonization in a hybrid thermal/nonthermal plasma. Anyway, the GRS 1758–258 and 1E 1740.7–2942 spectra are acceptably described by CompTT+po (jet) and Eqpair (hybrid Comptonization) scenarios. To differentiate between the two scenarios, we calculated the Spearman correlation coefficient comparing 30–50 keV count rates with those in higher energy bands (50–100, 100–300, and 300–600 keV). The count rates below 300 keV are strongly correlated, indicating those photons arise from the same physical process. Above 300 keV the count rates are either anticorrelated or not correlated with the 30–50 keV count rates for GRS 1758–258, which suggests that the photons originate from a different physical process. For 1E 1740.7–2942, the level of correlation is unclear due to scatter in the data points. However, the 300–600 keV count rates are consistent with a constant value. This disfavors the hybrid Comptonization scenario for both sources.}, archive = {J_ApJ}, author = {James Rodi and Angela Bazzano and Pietro Ubertini}, doi = {10.3847/1538-4357/adba49}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {145}, shortjournal = {The Astrophys. J.}, title = {High-energy jet emission from GRS 1758–258 and 1E 1740.7–2942 with INTEGRAL?}, volume = {982}, year = {2025}, }
• (2025). Where has all the R-process gone? timescales for gamma-ray burst kilonovae to enrich their host galaxies. ApJ, 982(2), 144. (www)

  @article{ , abstract = {Neutron star (NS) mergers are currently the only observed source of r -process production in the Universe. Yet, it is unclear how much r -process mass from these mergers is incorporated into star-forming gas to enrich stars. This is crucial to consider as all other r -process mass estimates in the Universe beyond Earth are based on stellar r -process abundances. Here, we explore the extent to which merger location and host-galaxy properties affect the incorporation of r -process elements into star-forming gas, and quantify an "enrichment" timescale to account for this process. To put this timescale in context, we analyze a population of 12 gamma-ray bursts (GRBs) with probable associations to r -process kilonovae (GRB-KNe) and 74 short GRBs without claimed KNe, including new nonparametric star formation histories for the GRB-KN hosts. We find the enrichment timescales for this sample are between ​​​​​​≈7 Myr and 1.6 Gyr, suggesting that environmental enrichment is delayed from NS merger occurrence. Moreover, we find a correlation between the amount of environmental enrichment from a single event and increasing host specific star formation rate (sSFR), and little correlation with stellar mass and GRB galactocentric offset. Environments with low sSFRs (<10 −10.5 yr −1 ), which comprise 18% of short-GRB hosts and the host of GW170817, will have little to no capacity for stellar enrichment. Our results indicate that not all r -process from NS mergers is incorporated into newly forming stars, and instead some remains "lost" to the circumgalactic medium or intergalactic medium. Future studies should consider these losses to understand the total contribution from NS mergers to the Universe's r -process budget.}, archive = {J_ApJ}, author = {Anya E. Nugent and Alexander P. Ji and Wen-fai Fong and Hilay Shah and Freeke van de Voort}, doi = {10.3847/1538-4357/adbb6a}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {144}, shortjournal = {The Astrophys. J.}, title = {Where has all the R-process gone? timescales for gamma-ray burst kilonovae to enrich their host galaxies}, volume = {982}, year = {2025}, }
• (2025). When is a bulge not a bulge? revealing the satellite nature of NGC 5474’s bulge. ApJ, 982(2), 143. (www)

  @article{ , abstract = {A satellite galaxy of the nearby spiral M101, NGC 5474 has a prominent bulge offset from the kinematic center of the underlying star-forming disk that has gained attention in recent years. Recent studies have proposed that this putative offset bulge is not a classical bulge within the plane of the disk but instead a dwarf companion galaxy along the line of sight. Using integral field spectroscopy data taken as part of the PPak IFS Nearby Galaxies Survey (PINGS), we perform the first analysis of the stellar and gas kinematics of this putative bulge (PB) and portions of the disk. We find a radial velocity offset of ∼24 km s −1 between the emission lines produced by the disk H ii regions and the absorption lines produced by the PB stellar component. We interpret this velocity offset as evidence that the PB and disk are two separate objects, the former orbiting around the latter, supporting simulations and observations of this peculiar system. We attempt to place this external companion into the context of the M101 Group and the M101-NGC 5474 interaction.}, archive = {J_ApJ}, author = {Ray Garner and J. Christopher Mihos and F. Fabián Rosales-Ortega}, doi = {10.3847/1538-4357/adbbd0}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {143}, shortjournal = {The Astrophys. J.}, title = {When is a bulge not a bulge? revealing the satellite nature of NGC 5474’s bulge}, volume = {982}, year = {2025}, }
• (2025). Metis observations of alfvénic outflows driven by interchange reconnection in a pseudostreamer. ApJ, 982(2), 142. (www)

  @article{ , abstract = {This study presents observations of a large pseudostreamer solar eruption and, in particular, the post-eruption relaxation phase, as captured by Metis, on board the Solar Orbiter, on 2022 October 12, during its perihelion passage. Utilizing total-brightness data, we observe the outward propagation of helical features up to 3 solar radii along a radial column that appears to correspond to the stalk of the pseudostreamer. The helical structures persisted for more than 3 hr following a jet-like coronal mass ejection associated with a polar crown prominence eruption. A notable trend is revealed: the inclination of these features decreases as their polar angle and height increase. Additionally, we measured their helix pitch. Despite the 2 minute time cadence limiting direct correspondence among filamentary structures in consecutive frames, we find that the Metis helical structure may be interpreted as a consequence of twist (nonlinear torsional Alfvén waves) and plasma liberated by interchange reconnection. A comparison was performed between the helix parameters as outlined by fine-scale outflow features and those obtained from synthetic white-light images derived from the high-resolution magnetohydrodynamics simulation of interchange reconnection in a pseudostreamer topology by P. F. Wyper et al. A remarkable similarity between the simulation-derived images and the observations was found. We conjecture that these Metis observations may represent the upper ends of the spatial and energy scales of the interchange reconnection process that has been proposed recently as the origin of the Alfvénic solar wind.}, archive = {J_ApJ}, author = {P. Romano and P. Wyper and V. Andretta and S. Antiochos and G. Russano and D. Spadaro and L. Abbo and L. Contarino and A. Elmhamdi and F. Ferrente and R. Lionello and B. J. Lynch and P. MacNeice and M. Romoli and R. Ventura and N. Viall and A. Bemporad and A. Burtovoi and V. Da Deppo and Y. De Leo and S. Fineschi and F. Frassati and S. Giordano and S. L. Guglielmino and C. Grimani and P. Heinzel and G. Jerse and F. Landini and G. Naletto and M. Pancrazzi and C. Sasso and M. Stangalini and R. Susino and D. Telloni and L. Teriaca and M. Uslenghi}, doi = {10.3847/1538-4357/adb1da}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {142}, shortjournal = {The Astrophys. J.}, title = {Metis observations of alfvénic outflows driven by interchange reconnection in a pseudostreamer}, volume = {982}, year = {2025}, }
• (2025). Magnetic field structures in and around seyfert galaxy outflows. ApJ, 982(2), 141. (www)

  @article{ , abstract = {We present radio polarimetric images of 12 Seyfert and low-ionization nuclear emission-line region (LINER) galaxies belonging to the Centre for Astrophysics +12 μ m sample exhibiting kiloparsec-scale radio outflows (KSRs). These observations have been carried out at 10 GHz with the Karl G. Jansky Very Large Array in D array and at 1.4 GHz with the BnA → A array configurations. We find signatures of organized magnetic ( B ) field structures in the cores, jets, and lobes of these galaxies. The linear polarization fraction varies from a few percent in the cores to 47% ± 18% in the lobes. The inferred B fields are toroidal in the cores of several sources making them consistent with the presence of either a sheath-like or a wind-like component surrounding the jet. The in-band spectral index images typically show the presence of flat/inverted spectrum cores and steep spectrum lobes. Radio cores with flatter spectra are found to have lower Eddington ratios, while the steeper ones have higher. A strong correlation is observed between the Seyfert/LINER radio outflow properties and the mass of the supermassive black holes; correlations with Eddington ratios are weaker. We find signatures of jet-medium interaction and both positive and negative active galactic nuclei (AGN) feedback in these sources. Overall, our study indicates that radio-quiet AGN with KSRs possess radio outflows driven by magnetic fields anchored to their black hole—accretion disk systems, which significantly impact their environments.}, archive = {J_ApJ}, author = {Salmoli Ghosh and Preeti Kharb and Biny Sebastian and Jack Gallimore and Alice Pasetto and Christopher P. O’Dea and Timothy Heckman and Stefi A. Baum}, doi = {10.3847/1538-4357/adae05}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {141}, shortjournal = {The Astrophys. J.}, title = {Magnetic field structures in and around seyfert galaxy outflows}, volume = {982}, year = {2025}, }
• (2025). Linking stellar populations to h ii regions across nearby galaxies. II. infrared reprocessed and UV direct radiation pressure in h ii regions. ApJ, 982(2), 140. (www)

  @article{ , abstract = {Radiation pressure is a key mechanism by which stellar feedback disrupts molecular clouds and drives H ii region expansion. This includes direct radiation pressure exerted by UV photons on dust grains, pressure associated with photoionization, and infrared (IR) radiation pressure on grains due to dust-reprocessed IR photons. We present a new method that combines high-resolution mid-IR luminosities from JWST-MIRI, optical attenuation, and nebular line measurements from the Very Large Telecope Multi-Unit Spectroscopic Explorer (VLT-MUSE), and the Hubble Space Telescope (HST) H α -based region sizes to estimate the strength of radiation pressure in ≈18,000 H ii regions across 19 nearby star-forming galaxies. This is the most extensive and direct estimate of these terms beyond the Local Group to date. In the disks of galaxies, we find that the total reprocessed IR pressure is on average 5% of the direct UV radiation pressure. This fraction rises to 10% in galaxy centers. We expect reprocessed IR radiation pressure to dominate over UV radiation pressure in regions where {L}_{{\rm{F2100W}}}/{L}_{{\rm{H}}\alpha }^{{\rm{corr}}}\gtrsim 75 . Radiation pressure due to H ionizations is lower than pressure on dust in our sample, but appears likely to dominate the radiation pressure budget in dwarf galaxies similar to the Small Magellanic Cloud. The contribution from all radiation pressure terms appears to be subdominant compared to thermal pressure from ionized gas, reinforcing the view that radiation pressure is most important in compact, heavily embedded, and young regions.}, archive = {J_ApJ}, author = {Debosmita Pathak and Adam K. Leroy and Todd A. Thompson and Laura A. Lopez and Ashley. T. Barnes and Daniel A. Dale and Ian Blackstone and Simon C. O. Glover and Shyam H. Menon and Jessica Sutter and Thomas G. Williams and Dalya Baron and Francesco Belfiore and Frank Bigiel and Alberto D. Bolatto and Médéric Boquien and Rupali Chandar and Mélanie Chevance and Ryan Chown and Kathryn Grasha and Brent Groves and Ralf S. Klessen and Kathryn Kreckel and Jing Li and J. Eduardo Méndez-Delgado and Erik Rosolowsky and Karin Sandstrom and Sumit K. Sarbadhicary and Jiayi Sun and Leonardo Úbeda}, doi = {10.3847/1538-4357/adb484}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {140}, shortjournal = {The Astrophys. J.}, title = {Linking stellar populations to h ii regions across nearby galaxies. II. infrared reprocessed and UV direct radiation pressure in h ii regions}, volume = {982}, year = {2025}, }
• (2025). Graph-based recursive relations for computing and analyzing r-process abundances. ApJ, 982(2), 139. (www)

  @article{ , abstract = {We develop recursive relations among abundances in an r -process network evolving neutron captures, photodisintegrations and beta decays through the use of the matrix-tree and matrix-forest theorems. Since these theorems are based on results from graph theory, we term the relations the GrRproc (Graphical R -process) relations. We validate the relations by using them to compute r -process abundances in network calculations in different astrophysical environments. We also illustrate how they can be used to follow complex reaction flows quantitatively in an evolving r -process network through the concept of contribution paths. Such contribution paths show how particular reactions govern the evolution of abundance features during the nucleosynthesis and, consequently, can clarify the role of key nuclear data and astrophysical environments in that evolution. The Python open-source package that implements the tool is freely available.}, archive = {J_ApJ}, author = {Mengke Li and Bradley S. Meyer}, doi = {10.3847/1538-4357/adb625}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {139}, shortjournal = {The Astrophys. J.}, title = {Graph-based recursive relations for computing and analyzing r-process abundances}, volume = {982}, year = {2025}, }
• (2025). The life and times of star-forming cores: An analysis of dense gas in the STARFORGE simulations. ApJ, 982(2), 138. (www)

  @article{ , abstract = {Dense gas in molecular clouds is an important signature of ongoing and future star formation. We identify and track dense cores in the starforge simulations, following the core evolution from birth through dispersal by stellar feedback for typical Milky Way cloud conditions. Only ∼8% of cores host protostars, and most disperse before forming stars. The median starless and protostellar core lifetimes are ∼0.5–0.6 Myr and ∼0.8–1.1 Myr, respectively, where the protostellar phase lasts \sim 0.{1}_{-0.05}^{+0.1} Myr. While core evolution is stochastic, we find that virial ratios and line widths decline in prestellar cores, coincident with turbulent decay. Collapse occurs over ∼0.1 Myr, once the central density exceeds ≳10 6 cm −3 . Starless cores, only, follow line-width–size and mass–size relations, σ ∝ R 0.3 and M ∝ R 1 . The core median mass, radius, and velocity dispersion scale weakly with the cloud magnetic field strength. We cluster the core properties and find that protostellar cores have >80% likelihood of belonging to three particular groups that are characterized by high central densities, compact radii, and lower virial parameters. Overall, core evolution appears to be universally set by the interplay of gravity and magnetized turbulence, while stellar feedback dictates protostellar core properties and sets the protostellar phase lifetime.}, archive = {J_ApJ}, author = {Stella S. R. Offner and Josh Taylor and Michael Y. Grudíc}, doi = {10.3847/1538-4357/adb71d}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {138}, shortjournal = {The Astrophys. J.}, title = {The life and times of star-forming cores: An analysis of dense gas in the STARFORGE simulations}, volume = {982}, year = {2025}, }
• (2025). The effect of radiation and supernovae feedback on LyC escape in local star-forming galaxies. ApJ, 982(2), 137. (www)

  @article{ , abstract = {Feedback is widely recognized as an essential condition for Lyman continuum (LyC) escape in star-forming galaxies. However, the mechanisms by which galactic outflows clear neutral gas and dust remain unclear. In this paper, we model the Mg ii 2796 Å, 2804 Å absorption and emission lines in 29 galaxies taken from the Low- z LyC Survey to investigate the impact of (radiation and mechanical) feedback on LyC escape. Using constraints on Mg + and photoionization models, we map the outflows' neutral hydrogen content and predict {f}_{{\rm{esc}}}^{{\rm{LyC}}} with a multiphase wind model. We measure mass-, momentum, and energy loading factors for the neutral winds, which carry up to 10% of the momentum and 1% of the energy in star formation rate (SFR)-based deposition rates. We use spectral energy distribution template fitting to determine the relative ages of stellar populations, allowing us to identify radiation feedback dominant systems. We then examine feedback related properties (stellar age, loading factors, etc.) under conditions that optimize feedback efficiency, specifically high-SFR surface density and compactness. Our findings indicate that the strongest leakers are radiation feedback dominant, lack deep Mg ii absorption features, but have extended broad components in higher-ionization lines like [O iii ] 5007 Å, as observed by Amorín et al. In contrast, galaxies experiencing supernovae feedback typically exhibit weaker {f}_{{\rm{esc}}}^{{\rm{LyC}}} and show evidence of outflows in both Mg ii and higher-ionization lines. We attribute these findings to enhanced LyC escape facilitated by turbulence and cloud fragmentation in intense radiation fields, prolonged in low-metallicity environments experiencing delayed supernova feedback.}, archive = {J_ApJ}, author = {Cody A. Carr and Renyue Cen and Claudia Scarlata and Xinfeng Xu and Alaina Henry and Rui Marques-Chaves and Daniel Schaerer and Ricardo O. Amorín and M. S. Oey and Lena Komarova and Sophia Flury and Anne Jaskot and Alberto Saldana-Lopez and Zhiyuan Ji and Mason Huberty and Timothy Heckman and Göran Östlin and Omkar Bait and Matthew James Hayes and Trinh Thuan and Swara Ravindranath and Danielle A. Berg and Mauro Giavalisco and Michael Rutkowski and Sanchayeeta Borthakur and John Chisholm and Harry C. Ferguson and Leo Michel-Dansac and Anne Verhamme and Gábor Worseck}, doi = {10.3847/1538-4357/adb72f}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {137}, shortjournal = {The Astrophys. J.}, title = {The effect of radiation and supernovae feedback on LyC escape in local star-forming galaxies}, volume = {982}, year = {2025}, }
• (2025). Polarization estimation for radio pulsars. ApJ, 982(2), 136. (www)

  @article{ , abstract = {A number of polarization estimators have been developed for a variety of astrophysical applications to compensate measurements of linear polarization for a bias contributed by the instrumental noise. Most derivations of the estimators assume that the amplitude and orientation of the polarization vector are constant. This assumption generally is not valid for the radio emission from pulsars that fluctuates from pulse to pulse. The radio emission from pulsars, fast radio bursts, and magnetars can be elliptically polarized, and estimators of the total polarization and absolute value of the circular polarization are used in their observations. However, these estimators have not been formally developed to a level that is commensurate with those of linear polarization. Estimators are derived for circular, linear, and total polarization when the amplitude of the polarization vector is a constant or a random variable. Hybrid estimators are proposed for general application to pulsar polarization observations. They are shown to be more effective at removing instrumental noise than their commonly used counterparts.}, archive = {J_ApJ}, author = {M. M. McKinnon}, doi = {10.3847/1538-4357/adb7e1}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {136}, shortjournal = {The Astrophys. J.}, title = {Polarization estimation for radio pulsars}, volume = {982}, year = {2025}, }
• (2025). Observations and radiative transfer simulations of the carbon-rich AGB star v oph with VLTI/MATISSE*. ApJ, 982(2), 135. (www)

  @article{ , abstract = {Carbon-rich asymptotic giant branch (AGB) stars are among the most important contributors of enriched materials to the interstellar medium due to their strong stellar winds. To fully characterize mass loss on the AGB, it is necessary to determine the distributions of dust and gas around the stars, where the dust begins to condense from the gas, and how this extended atmospheric structure evolves over the pulsational period of the star. We present an analysis of L -band (2.8–4.2 μ m) interferometric observations of the carbon-rich AGB star V Oph made with the MATISSE instrument at the Very Large Telescope Interferometer at the maximum and minimum of the star's visual light curve. Using the radiative transfer software RADMC-3D, we model the circumstellar dust shell, and find stellar radii of 395 and 495 R ⊙ at the two phases, and dust radii of 790 and 742.5 R ⊙ at the two epochs, respectively. By adding C 2 H 2 and HCN gas to the RADMC-3D models, we are able to fit the visibility spectra well, with some deviations at the 3.11 μ m feature. Reasons for this deviation and interpretation of the best fitting models are discussed in the text, and we discuss motivations for follow-up imaging observations of V Oph.}, archive = {J_ApJ}, author = {Jon Hulberg and Gioia Rau and Markus Wittkowski}, doi = {10.3847/1538-4357/adb7e2}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {135}, shortjournal = {The Astrophys. J.}, title = {Observations and radiative transfer simulations of the carbon-rich AGB star v oph with VLTI/MATISSE*}, volume = {982}, year = {2025}, }
• (2025). BASS. XLV. quantifying active galactic nuclei selection effects in the chandra COSMOS-legacy survey with BASS. ApJ, 982(2), 134. (www)

  @article{ , abstract = {Deep extragalactic X-ray surveys, such as the Chandra COSMOS-Legacy field (CCLS), are prone to be biased against active galactic nuclei (AGN) with high column densities due to their lower count rates at a given luminosity. To quantify this selection effect, we forward model nearby ( z ∼ 0.05) AGN from the BAT AGN Spectroscopic Survey (BASS) with well-characterized (≳1000 cts) broadband X-ray spectra (0.5–195 keV) to simulate the CCLS absorption distribution. We utilize the BASS low-redshift analogs with similar luminosities to the CCLS ( {L}_{2-10\,{\rm{keV}}}^{{\rm{int}}} ∼ 10 42−45 erg s), which are much less affected by obscuration and low-count statistics, as the seed for our simulations and follow the spectral fitting of the CCLS. Our simulations reveal that Chandra would fail to detect the majority (53.3%; 563/1056) of obscured ( N H ≥ 10 22 cm −2 ) simulated BASS AGN given the observed redshift and luminosity distribution of the CCLS. Even for detected sources with sufficient counts (≥30) for spectral modeling, the level of obscuration is significantly overestimated. This bias is most extreme for objects whose best fit indicates a high-column density AGN ( N H ≥ 10 24 cm −2 ), since the majority (66.7%; 18/27) of these are actually unobscured sources ( N H < 10 22 cm −2 ). This implies that previous studies may have significantly overestimated the increase in the obscured fraction with redshift and the fraction of luminous obscured AGN. Our findings highlight the importance of directly considering obscuration biases and forward modeling in X-ray surveys, as well as the need for higher-sensitivity X-ray missions such as the Advanced X-ray Imaging Satellite (AXIS), and the importance of multiwavelength indicators to estimate obscuration in distant supermassive black holes.}, archive = {J_ApJ}, author = {Yarone M. Tokayer and Michael J. Koss and C. Megan Urry and Priyamvada Natarajan and Richard Mushotzky and Mislav Baloković and Franz E. Bauer and Peter Boorman and Alessandro Peca and Claudio Ricci and Federica Ricci and Daniel Stern and Ezequiel Treister and Benny Trakhtenbrot}, doi = {10.3847/1538-4357/adb8c9}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {134}, shortjournal = {The Astrophys. J.}, title = {BASS. XLV. quantifying active galactic nuclei selection effects in the chandra COSMOS-legacy survey with BASS}, volume = {982}, year = {2025}, }
• (2025). Can neutron star tidal effects obscure deviations from general relativity?. ApJ, 982(2), 133. (www)

  @article{ , abstract = {One of the main goals of gravitational-wave astrophysics is to study gravity in the strong-field regime and constrain deviations from general relativity (GR). Any such deviation affects not only binary dynamics and gravitational-wave emission but also the structure and tidal properties of compact objects. In the case of neutron stars, masses, radii, and tidal deformabilities can all differ significantly between different theories of gravity. Currently, the measurement uncertainties in neutron star radii and tidal deformabilities are quite large. However, much less is known about how the large uncertainty in the nuclear equation of state (EOS) might affect tests of GR using binary neutron star mergers. Conversely, using the wrong theory of gravity might lead to incorrect constraints on the nuclear EOS. Here, we study this problem within scalar–tensor (ST) theory. We apply the recently derived ℓ = 2 tidal Love numbers in this theory to parameter estimation of GW170817. Correspondingly, we test if physics beyond GR could bias measurements of the nuclear EOS and neutron star radii. We find that parameter inference for both the GR and ST cases returns consistent component masses and tidal deformabilities. The radius and the EOS posteriors, however, differ between the two theories, but neither is excluded by current observational limits. This indicates that measurements of the nuclear EOS may be biased and that deviations from GR could go undetected when analyzing current binary neutron star mergers.}, archive = {J_ApJ}, author = {Stephanie M. Brown and Badri Krishnan and Rahul Somasundaram and Ingo Tews}, doi = {10.3847/1538-4357/adb966}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {133}, shortjournal = {The Astrophys. J.}, title = {Can neutron star tidal effects obscure deviations from general relativity?}, volume = {982}, year = {2025}, }
• (2025). A multifrequency census of 100 pulsars below 100 MHz with LWA: A systematic study of flux density, spectra, timing, dispersion, polarization, and its variation from a decade of observations. ApJ, 982(2), 132. (www)

  @article{ , abstract = {We present a census of 100 pulsars, the largest below 100 MHz, including 94 normal pulsars and six millisecond pulsars, with the Long Wavelength Array (LWA). Pulse profiles are detected across a range of frequencies from 26–88 MHz, including new narrowband profiles facilitating profile evolution studies, and breaks in pulsar spectra at low frequencies. We report mean flux density, spectral index, curvature, and low-frequency turnover-frequency measurements for 97 pulsars, including new measurements for 61 sources. Multifrequency profile widths are presented for all pulsars, including component spacing for 27 pulsars with two components. Polarized emission is detected from 27 of the sources (the largest sample at these frequencies) in multiple frequency bands, with one new detection. We also provide new timing solutions for five recently discovered pulsars. Low-frequency observations with the LWA are especially sensitive to propagation effects arising in the interstellar medium. We have made the most sensitive measurements of pulsar dispersion measures (DMs) and rotation measures, with median uncertainties of 2.9 × 10 −4 pc cm −3 and 0.01 rad m −2 , respectively, and can track their variations over almost a decade, along with other frequency-dependent effects. This allows for stringent limits on average magnetic fields, with no variations detected above ∼20 nG. Finally, the census yields some interesting phenomena in individual sources, including the detection of frequency- and time-dependent DM variations in B2217+47, and the detection of highly circularly polarized emission from J0051+0423.}, archive = {J_ApJ}, author = {P. Kumar and G. B. Taylor and K. Stovall and J. Dowell and S. M. White}, doi = {10.3847/1538-4357/adb97a}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {132}, shortjournal = {The Astrophys. J.}, title = {A multifrequency census of 100 pulsars below 100 MHz with LWA: A systematic study of flux density, spectra, timing, dispersion, polarization, and its variation from a decade of observations}, volume = {982}, year = {2025}, }
• (2025). Filament mass losses forced by magnetic reconnection in the solar corona. ApJ, 982(2), 131. (www)

  @article{ , abstract = {Recent observations of the solar atmosphere in cool extreme-ultraviolet lines have reported the prevalence of coronal rain falling from coronal cloud filaments that are associated with the magnetic dips of coronal X-point structures. These filaments mysteriously appear as clouds of mass in the corona that subsequently shrink and disappear due to mass losses that drain as coronal rain along arced field lines. Using a two-and-a-half-dimensional magnetohydrodynamic model, we investigated evaporation-condensation as the formation mechanism of the subset of coronal cloud filaments that form above coronal X-points. Our simulation included the effects of field-aligned thermal conduction and optically thin radiation, and used the state-of-the-art transition region adaptive conduction (TRAC) method to model the formation, maintenance, and mass loss of a filament above a coronal X-point. This paper presents a physical model that demonstrates magnetic reconnection as a filament loss mechanism, producing hybrid filament/coronal rain via mass losses through the X-point. A detailed analysis of how the mass of the filament forces the field to reconnect is also presented, revealing three phases that characterize the evolution of the reconnecting current sheet and associated mass losses. We conclude that the formation of certain coronal cloud filaments and subsequent mass losses via coronal rain can be explained by the evaporation-condensation model combined with filament mass losses forced by magnetic reconnection. We also report that rebound shocks generated by the impact of coronal rain condensations on the chromosphere together with retractive upflows can cause upward-propagating condensations to form through a dynamic thermal runaway process.}, archive = {J_ApJ}, author = {Craig D. Johnston and Lars K. S. Daldorff and Peter W. Schuck and Mark G. Linton and Will T. Barnes and James E. Leake and Simon Daley-Yates}, doi = {10.3847/1538-4357/adbae8}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {131}, shortjournal = {The Astrophys. J.}, title = {Filament mass losses forced by magnetic reconnection in the solar corona}, volume = {982}, year = {2025}, }
• (2025). SDSS-IV MaNGA: Spatial evolution of gas-phase metallicity changes induced by galaxy interactions. ApJ, 982(2), 130. (www)

  @article{ , abstract = {Gas-phase metallicity in interacting and merging galaxies offers key insights into their star formation processes and evolutionary histories. This study investigates the spatial evolution of gas-phase metallicity (i.e., oxygen abundance, 12 + log(O/H)) in these galaxies using integral field unit data from the SDSS-IV MaNGA survey, focusing on changes in metallicity gradients across different stages of interactions—from early encounters to final coalescence. By comparing interacting and merging galaxies with isolated counterparts, we identify characteristic trends in how interactions influence metallicity gradients over time. Our analysis reveals that metallicity gradients typically flatten shortly after the first pericenter passage, likely due to radial gas mixing, with later stages showing either metallicity enrichment or dilution depending on the intensity of the interaction and star formation activity. These changes can result in gradients that are either flatter or steeper than the initial profiles. Notably, we observe steeper metallicity gradients in interacting galaxies at certain merger stages, which is inconsistent with predictions from some galaxy simulations. This discrepancy emphasizes the complexity of galaxy interactions. Overall, our findings provide valuable insights into how galaxy interactions reshape metallicity distribution, enhancing our understanding of the processes driving galaxy evolution during mergers.}, archive = {J_ApJ}, author = {Hsi-An Pan and Lihwai Lin and Sebastián F. Sánchez and Jorge K. Barrera-Ballesteros and Bau-Ching Hsieh}, doi = {10.3847/1538-4357/adbbd2}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {130}, shortjournal = {The Astrophys. J.}, title = {SDSS-IV MaNGA: Spatial evolution of gas-phase metallicity changes induced by galaxy interactions}, volume = {982}, year = {2025}, }
• (2025). Identification and analysis of galactic bars in DESI legacy imaging surveys. ApJ, 982(2), 129. (www)

  @article{ , abstract = {We present a comprehensive study of bar structures in the local universe using data from the DESI Legacy Imaging Surveys. Through isophotal analysis of 232,142 galaxies, we identify bars and classify them into strong and weak categories based on normalized bar length, using a threshold of 0.4. We find a total bar fraction of 42.9%, rising to 62.0% in disk galaxies, with strong barred galaxies accounting for 30.0%. For barred galaxies in our sample, deprojected bar lengths are measured both in absolute terms and normalized by galaxy size. Most bars are found to have absolute lengths of 3–7 kpc, and normalized bar lengths concentrated around a median value of 0.4. Bar ellipticity mainly ranges from 0.2 to 0.6, with a median value of 0.3. Our analysis reveals a bimodal distribution of bar fractions with respect to galaxy color, with weak bars in our classification being more prevalent in intermediate-color systems. With respect to stellar mass, strong bars also present a bimodal distribution, while weak bars are distributed uniformly. Normalized bar length remains relatively stable across stellar masses, while absolute bar length positively correlates with stellar mass. Cross-validation with visual classifications from Galaxy Zoo DESI catalog confirms a bar identification accuracy of 93%. These results validate our automated method for bar identification and measurement, demonstrating its reliability. Our findings underscore the importance of bars in galaxy evolution and highlight the potential of upcoming wide-field surveys to deepen our understanding of barred galaxies.}, archive = {J_ApJ}, author = {Wenwen Wang and Zhimin Zhou}, doi = {10.3847/1538-4357/adbcac}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {129}, shortjournal = {The Astrophys. J.}, title = {Identification and analysis of galactic bars in DESI legacy imaging surveys}, volume = {982}, year = {2025}, }
• (2025). Simulation-based prediction of black hole X-ray spectra and spectral variability. ApJ, 982(2), 128. (www)

  @article{ , abstract = {Data derived from general relativistic magnetohydrodynamic simulations of accretion onto black holes can be used as input to a postprocessing scheme that predicts the radiated spectrum. Combining a relativistic Compton scattering radiation transfer solution in the corona with detailed local atmosphere solutions incorporating local ionization and thermal balance within the disk photosphere, it is possible to study both spectral formation and intrinsic spectral variability in the radiation from relativistic accretion disks. With this method, we find that radiatively efficient systems with black holes of 10 M ⊙ accreting at ≈0.01 in Eddington units produce spectra very similar to those observed in the hard states of X-ray binaries. The spectral shape above 10 keV is well described by a power law with an exponential cutoff. Intrinsic turbulent variations lead to order-unity changes in bolometric luminosity, variations in the logarithmic spectral slope ∼0.1, and factor of 2 alterations in the cutoff energy on timescales ∼50 ( M BH /10 M ⊙ ) ms. Within the corona, the range of gas temperature spans more than 1 order of magnitude. The wide distribution of temperatures is central to defining the spectrum: the logarithmic spectral slope is harder by ∼0.3 and the cutoff energy larger by a factor ∼10–30 than if the coronal temperature everywhere were its mass-weighted mean.}, archive = {J_ApJ}, author = {Rongrong Liu and Chris Nagele and Julian H. Krolik and Brooks E. Kinch and Jeremy D. Schnittman}, doi = {10.3847/1538-4357/adb61f}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {128}, shortjournal = {The Astrophys. J.}, title = {Simulation-based prediction of black hole X-ray spectra and spectral variability}, volume = {982}, year = {2025}, }
• (2025). Superoutbursts and positive superhumps occurred during the standstill of a z cam-type dwarf nova. ApJ, 982(2), 127. (www)

  @article{ , abstract = {Dwarf novae (DNe) are semidetached binaries, where a white dwarf accretes material from a cool main-sequence companion via an accretion disk, and are known for their intermittent outbursts, making them key systems for studying accretion physics. The accumulation of large survey data sets has challenged traditional models, which assumed that the disk remains hot and cannot produce superoutbursts during the standstill of a Z Camelopardalis (Z Cam)-type DN and that superoutbursts require a mass ratio of q = M 2 / M 1 ≤ 0.25–0.33. Here we report the detection of superoutbursts and positive superhumps (PSHs) during a standstill in the Z Cam-type star AT Cnc with a mass ratio larger than 0.33. Notably, the PSHs evolve gradually before the superoutburst begins, suggesting that an eccentric, precessing disk forms first, with the superoutburst occurring as the disk radius continues to expand. These findings provide the first detailed observational evidence of superoutbursts and PSHs occurring during standstill, offering important new insights into the classification of DNe and the underlying mechanisms of outbursts.}, archive = {J_ApJ}, author = {Qi-Bin Sun and Sheng-Bang Qian and Li-Ying Zhu and Qin-Mei Li and Fu-Xing Li and Min-Yu Li and Ping Li}, doi = {10.3847/1538-4357/adb7d9}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {127}, shortjournal = {The Astrophys. J.}, title = {Superoutbursts and positive superhumps occurred during the standstill of a z cam-type dwarf nova}, volume = {982}, year = {2025}, }
• (2025). Magnetic thomson transport in high-opacity domains. ApJ, 982(2), 126. (www)

  @article{ , abstract = {X-ray radiation from neutron stars manifests itself in a variety of settings. Isolated pulsars and magnetars both exhibit quasi-thermal persistent soft X-ray emission from their surfaces. Transient magnetospheric bursts from magnetars and pulsed signals from accreting neutron stars mostly appear in harder X-rays. The emission zones pertinent to these signals are all highly Thomson optically thick, so that their radiation anisotropy and polarization can be modeled using sophisticated simulations of scattering transport from extended emission regions. Validation of such codes and their efficient construction is enhanced by a deep understanding of scattering transport in high-opacity domains. This paper presents a new analysis of the polarized magnetic Thomson radiative transfer in the asymptotic limit of high opacity. The integrodifferential equations for photon scattering transport that result from a phase matrix construction are reduced to a compact pair of equations. This pair is then solved numerically for two key parameters that describe the photon anisotropy and polarization configuration of high Thomson opacity environs. Empirical approximations for these parameters as functions of the ratio of the photon and cyclotron frequencies are presented. Implementation of these semi-analytic transport solutions as interior boundary conditions is shown to speed up scattering simulations. The solutions also enable the specification of the anisotropic radiation pressure. The analysis is directly applicable to the atmospheres of magnetars and moderate-field pulsars, and to the accretion columns of magnetized X-ray binaries, and can be adapted to address other neutron star settings.}, archive = {J_ApJ}, author = {Matthew G. Baring and Kun Hu and Hoa Dinh Thi}, doi = {10.3847/1538-4357/adb848}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {126}, shortjournal = {The Astrophys. J.}, title = {Magnetic thomson transport in high-opacity domains}, volume = {982}, year = {2025}, }
• (2025). RUBIES: JWST/NIRSpec resolves evolutionary phases of dusty star-forming galaxies at z ∼ 2. ApJ, 982(2), 125. (www)

  @article{ , abstract = {The dearth of high-quality spectroscopy of dusty star-forming galaxies (DSFGs)—the main drivers of the assembly of dust and stellar mass at the peak of activity in the Universe—greatly hinders our ability to interpret their physical processes and evolutionary pathways. We present JWST/NIRSpec observations from RUBIES of four submillimeter-selected, Atacama Large Millimeter/submillimeter Array (ALMA)-detected DSFGs at cosmic noon, z ∼ 2.3–2.7. While photometry uniformly suggests vigorous ongoing star formation for the entire sample in line with canonical DSFGs, the spectra differ: one source has spectroscopic evidence of an evolved stellar population, indicating a recent transition to a post-starburst phase, while the remainder show strong spectroscopic signatures of ongoing starbursts. All four galaxies are infrared luminous (log 10 L IR / L ⊙ > 12.4), massive (log 10 M ⋆ / M ⊙ > 11), and very dust obscured ( A V ∼ 3–4 ABmag). Leveraging detections of multiple Balmer and Paschen lines, we derive an optical attenuation curve consistent with Calzetti overall, yet an optical extinction ratio R V ∼ 2.5, potentially indicating smaller dust grains or differences in star-dust geometry. This case study provides some of the first detailed spectroscopic evidence that the DSFGs encompass a heterogeneous sample spanning a range of star formation properties and evolutionary stages, and illustrates the advantages of synergistic JWST and ALMA analysis of DSFGs.}, archive = {J_ApJ}, author = {Olivia R. Cooper and Gabriel Brammer and Kasper E. Heintz and Sune Toft and Caitlin M. Casey and David J. Setton and Anna de Graaff and Leindert Boogaard and Nikko J. Cleri and Steven Gillman and Rashmi Gottumukkala and Jenny E. Greene and Bitten Gullberg and Michaela Hirschmann and Raphael E. Hviding and Erini Lambrides and Joel Leja and Arianna S. Long and Sinclaire M. Manning and Michael V. Maseda and Ian McConachie and Jed McKinney and Desika Narayanan and Sedona H. Price and Victoria Strait and Katherine A. Suess and Andrea Weibel and Christina C. Williams}, doi = {10.3847/1538-4357/adb8e1}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {125}, shortjournal = {The Astrophys. J.}, title = {RUBIES: JWST/NIRSpec resolves evolutionary phases of dusty star-forming galaxies at z ∼ 2}, volume = {982}, year = {2025}, }
• (2025). Redshift distributions of fast radio bursts inferred using clustering in dispersion measure space. ApJ, 982(2), 124. (www)

  @article{ , abstract = {Fast radio bursts (FRBs), millisecond-duration radio transient events, possess the potential to serve as excellent cosmological probes. The FRB redshift distribution contains information about the FRB sources, providing key constraints on the types of engines. However, it is quite challenging to obtain the FRB redshifts due to the poor localization and the faintness of the host galaxies. This reality severely restricts the application prospects and study of the physical origins of FRBs. We propose that the clustering of observed FRBs can be an effective approach to address this issue without needing to accurately model dispersion measure (DM) contributions from the host galaxy and the immediate environment of the source. Using the clustering of 5 × 10 7 simulated FRBs from future observations with sensitivity similar to the second phase of the Square Kilometre Array, we show that in extragalactic DM space, the redshift distributions can be accurately reconstructed, and the mean redshift for FRBs between 384.8 and 1450.3 pc cm −3 can be constrained to ∼0.001 ± 0.003(1 + z ). The results demonstrate the potential of FRB clustering to constrain redshift distributions and provide valuable insights into FRB source models and cosmological applications.}, archive = {J_ApJ}, author = {Hui Peng and Yu Yu}, doi = {10.3847/1538-4357/adbbda}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {124}, shortjournal = {The Astrophys. J.}, title = {Redshift distributions of fast radio bursts inferred using clustering in dispersion measure space}, volume = {982}, year = {2025}, }
• (2025). Argon in β Pictoris–Entrapment and release of volatile in disks. ApJ, 982(2), 123. (www)

  @article{ , abstract = {Chemical compositions of planets reveal much about their formation environments. Such information is well sought-after in studies of solar system bodies and extrasolar ones. Here, we investigate the composition of planetesimals in the β Pictoris debris disk by way of its secondary gas disk. We are stimulated by the recent JWST detection of an Ar ii emission line and aim to reproduce extensive measurements from the past four decades. Our photoionization model reveals that the gas has to be heavily enriched in C, N, O, and Ar (but not S and P), by a uniform factor of about 100 relative to other metals. Such an abundance pattern is both reminiscent of, and different from, that of Jupiter's atmosphere. The fact that Ar, the most volatile and therefore the hardest to capture into solids, is equally enriched as C, N, and O suggests that the planetesimals were formed in a very cold region ( T ≤ 20–35 K), possibly with the help of entrapment if water ice is overabundant. In the debris disk phase, these volatiles are preferentially outgassed from the dust grains, likely via photodesorption. The debris grains must be "dirty" aggregates of icy and refractory clusters. Lastly, the observed strength of the Ar ii line can only be explained if the star β Pic (a young A6V star) has sizable chromospheric and coronal emissions, on par with those from the modern Sun. In summary, observations of the β Pic gas disk rewind the clock to reveal the formation environment of planetesimals.}, archive = {J_ApJ}, author = {Yanqin Wu and Kadin Worthen and Alexis Brandeker and Christine Chen}, doi = {10.3847/1538-4357/ada287}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {123}, shortjournal = {The Astrophys. J.}, title = {Argon in β Pictoris–Entrapment and release of volatile in disks}, volume = {982}, year = {2025}, }
• (2025). Systematic study of the composition of type i X-ray burst ashes: Neutron star structure versus reaction rate uncertainties. ApJ, 982(2), 122. (www)

  @article{ , abstract = {In this study, we calculate for the first time the impacts of neutron star (NS) structure on the type I X-ray burst ashes using the MESA code. We find an increased mass fraction of the heavier elements with increasing surface gravity (increased mass or decreased radius), resulting in a higher average mass number ( A ash ) of burst ashes (except for higher-mass NSs due to the competition between the envelope temperature and the recurrence time). The burst strength ( α ) increases as the surface gravity increases, which indicates the positive correlation between A ash and α with changes in surface gravity. If the α value is higher, heavier p -nuclei should be produced by the type I X-ray burst nucleosynthesis. Besides, the effects of various burst input parameters, e.g., base heating ( Q b ), metallicity ( Z ), and some new reaction rates, are calculated for comparison. We find that the heavier nucleus synthesis is inversely correlated with the base heating/metallicity; the smaller the base heating/metallicity, the greater the mass fraction of the heavier elements. The α value decreases as Q b or Z decreases, which also indicates the positive correlation between A ash and α with variation in Q b or Z . The new reaction rates from the ( p , γ ) reactions on 17 F, 19 F, 26 P, 56 Cu, and 65 As and the ( α , p ) reaction on 22 Mg have only minimal effects on burst ashes. In hydrogen-rich X-ray binary systems, nuclei heavier than 64 Ge are fertile, produced with larger NS mass, smaller NS radius, smaller base heating, and smaller metallicity.}, archive = {J_ApJ}, author = {Guoqing Zhen and Helei Liu and Akira Dohi and Guoliang Lü and Nobuya Nishimura and Chunhua Zhu and Renxin Xu}, doi = {10.3847/1538-4357/adb71c}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {122}, shortjournal = {The Astrophys. J.}, title = {Systematic study of the composition of type i X-ray burst ashes: Neutron star structure versus reaction rate uncertainties}, volume = {982}, year = {2025}, }
• (2025). Estimating the sonic mach number in the interstellar medium with convolutional neural networks. ApJ, 982(2), 121. (www)

  @article{ , abstract = {Understanding the role of turbulence in shaping the interstellar medium (ISM) is crucial for studying star formation, molecular cloud evolution, and cosmic-ray propagation. Central to this is the measurement of the sonic Mach number ( M s ), which quantifies the ratio of turbulent velocity to the sound speed. In this work, we introduce a convolutional-neural-network-(CNN)-based approach for estimating M s directly from spectroscopic observations. The approach leverages the physical correlation between increasing M s and the shock-induced small-scale fluctuations that alter the morphological features in intensity, velocity centroid, and velocity channel maps. These maps, derived from 3D magnetohydrodynamic turbulence simulations, serve as inputs for the CNN training. By learning the relationship between these structural features and the underlying turbulence properties, CNNs can predict M s under various conditions, including different magnetic fields and levels of observational noise. The median uncertainty of the CNN-predicted M s ranges from 0.5 to 1.5 depending on the noise level. While intensity maps offer lower uncertainty, channel maps have the advantage of predicting the 3D M s distribution, which is crucial in estimating 3D magnetic field strength. Our results demonstrate that machine-learning-based tools can effectively characterize complex turbulence properties in the ISM.}, archive = {J_ApJ}, author = {Tyler Schmaltz and Yue Hu and Alex Lazarian}, doi = {10.3847/1538-4357/adb7ce}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {121}, shortjournal = {The Astrophys. J.}, title = {Estimating the sonic mach number in the interstellar medium with convolutional neural networks}, volume = {982}, year = {2025}, }
• (2025). No evidence of asymmetrically enhanced star formation in infalling galaxies in UNIONS. ApJ, 982(2), 120. (www)

  @article{ , abstract = {Ram pressure stripping is a well-known environmental quenching mechanism that removes gas from galaxies infalling into groups and clusters. In some extreme examples of ram pressure stripping, galaxies with extended gas tails show evidence of enhanced star formation prior to quenching. In this work we use a sample of 5277 local satellite galaxies in which a stripped tail of gas has not necessarily been observed, to quantify the strength of ram-pressure-enhanced star formation and compare these results to a control sample of 8360 field galaxies. We use u -band imaging from the Ultraviolet Near Infrared Optical Northern Survey (UNIONS) as a star formation tracer and several metrics to quantify star formation asymmetry. We compare these results to environmental properties of the galaxy, such as their time since infall and host halo mass, to constrain the degree of ram-pressure-enhanced star formation as a function of environment. We find no significant differences between the satellite and the field samples. We further restrict our sample to galaxies which we most expect to be experiencing significant ram pressure but find no strong evidence of these galaxies having systematically enhanced star formation. Finally, we investigate the properties of the most asymmetric galaxies in our sample and again find no strong evidence of ram-pressure-induced star formation enhancement. We conclude that any star formation enhancement must be small for infalling galaxies, suggesting that this effect is either uncommon or short-lived.}, archive = {J_ApJ}, author = {Lauren M. Foster and Laura C. Parker and Stephen Gwyn and Ian D. Roberts and James E. Taylor and Michael J. Hudson and Alan W. McConnachie and Thomas de Boer}, doi = {10.3847/1538-4357/adb8dc}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {120}, shortjournal = {The Astrophys. J.}, title = {No evidence of asymmetrically enhanced star formation in infalling galaxies in UNIONS}, volume = {982}, year = {2025}, }
• (2025). Unusual intraburst variations of polarization states in FRB 20210912A and FRB 20230708A: Effects of plasma birefringence?. ApJ, 982(2), 119. (www)

  @article{ , abstract = {Fast radio bursts (FRBs) are highly energetic events of short-duration intense radio emission, the origin of which remains elusive. Polarization of the FRB signals carries information about the emission source as well as the magnetoionic media the signal passes through before reaching terrestrial radio telescopes. Currently known FRBs show a diverse range of polarization, sometimes with complex features, making it challenging to describe them in a unified model. FRB 20230708A and FRB 20210912A are two bright and highly polarized (apparently) one-off FRBs detected in the Commensal Real-time ASKAP Fast Transients survey with the Australian Square Kilometre Array Pathfinder (ASKAP) that exhibit time-dependent conversion between linear and circular polarizations as well as intraburst (apparent) variation of the Faraday rotation measure. We investigate the intraburst temporal evolution of the polarization state of radio emission in these two events using the Poincaré sphere representation and find that the trajectories of the polarization state are well described by great circles on the Poincaré sphere. These polarization features may be signatures of a transition between two partially coherent orthogonal polarization modes or propagation through a birefringent medium. We find that the observed variations of the polarization states of these two FRBs are qualitatively consistent with a magnetospheric origin of the bursts and the effects of propagation through a birefringent medium with linearly polarized modes located close to the emission source—likely in the outer magnetosphere or near-wind region of a neutron star.}, archive = {J_ApJ}, author = {Apurba Bera and Clancy W. James and Mark M. McKinnon and Ronald D. Ekers and Tyson Dial and Adam T. Deller and Keith W. Bannister and Marcin Glowacki and Ryan M. Shannon}, doi = {10.3847/1538-4357/adba59}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {119}, shortjournal = {The Astrophys. J.}, title = {Unusual intraburst variations of polarization states in FRB 20210912A and FRB 20230708A: Effects of plasma birefringence?}, volume = {982}, year = {2025}, }
• (2025). The radio and microwave sky as seen by juno on its mission to jupiter. ApJ, 982(2), 118. (www)

  @article{ , abstract = {We present six nearly full-sky maps made from data taken by radiometers on the Juno satellite during its 5 yr flight to Jupiter. The maps represent integrated emission over ∼4% passbands spaced approximately in octaves between 600 MHz and 21.9 GHz. Long-timescale offset drifts are removed in all bands, and, for the two lowest-frequency bands, gain drifts are also removed from the maps via a self-calibration algorithm similar to the NPIPE pipeline used by the Planck Collaboration. We show that, after this solution is applied, statistical noise in the maps is consistent with thermal radiometer noise and expected levels of correlated noise on the gain and noise drift solutions. We verify our map solutions with several consistency tests and end-to-end simulations. We also estimate the level of systematic pixelization noise and polarization leakage via simulations.}, archive = {J_ApJ}, author = {C. J. Anderson and P. Berger and T.-C. Chang and O. Doré and S. Brown and S. Levin and M. Seiffert}, doi = {10.3847/1538-4357/adba62}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {118}, shortjournal = {The Astrophys. J.}, title = {The radio and microwave sky as seen by juno on its mission to jupiter}, volume = {982}, year = {2025}, }
• (2025). Discovery of 15 new pulsars at high galactic latitudes with FAST. ApJ, 982(2), 117. (www)

  @article{ , abstract = {We present the discovery and timing results for 15 pulsars discovered in a high-Galactic-latitude survey conducted with the Five-hundred-meter Aperture Spherical Telescope. The survey targeted a region as close as possible to the Galactic center, encompassing an area near the Galactic bulge. The newly discovered pulsars consist of 11 normal pulsars and four millisecond pulsars (MSPs). Among the MSPs, three are identified in binary systems with orbital periods of  ∼3.1, 4.6, and 12.5 days, respectively. We have successfully obtained coherent timing solutions for three of the normal pulsars (PSRs J1745−0059, J1746−0156, and J1800−0059). Furthermore, within our data set, we found that four pulsars (three new and one known) show mode-changing and/or subpulse-drifting phenomena. Comparing our discoveries with simulations of the Galactic disk and bulge MSP populations indicates that these new pulsars are most likely located in the disk. Nonetheless, our discoveries demonstrate that deep surveys at high Galactic latitudes have significant potential to enhance our understanding of the MSP population in the direction of the bulge.}, archive = {J_ApJ}, author = {Xin Xu and Shi Dai and Qijun Zhi and Juntao Bai and Joanna Berteaud and Francesca Calore and Maïca Clavel and Weiwei Zhu and Di Li and Rushuang Zhao and Renxin Xu and Guojun Qiao}, doi = {10.3847/1538-4357/adbb65}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {117}, shortjournal = {The Astrophys. J.}, title = {Discovery of 15 new pulsars at high galactic latitudes with FAST}, volume = {982}, year = {2025}, }
• (2025). Zonal flow and self-regulating mechanism in a hydrodynamic disk. ApJ, 982(2), 116. (www)

  @article{ , abstract = {This study addresses key aspects of momentum transport in hydrodynamic disks, which is critical for understanding zonal flow generation and turbulence in compressible hydrodynamic disks. We find that nonlinear momentum/density transport leads to the formation of zonal flows from the Rossby wave instability in disks. We analytically derive the generation and location of zonal flows and describe a modified Taylor identity applicable to compressible disk flows. We further present a self-regulation model, revealing a dynamic interplay between zonal flow and fluctuations driven by Rossby wave instability that regulates the nonlinear saturation state. This theoretical framework contributes insights into the dynamics of disks such as protoplanetary disks, shedding light on the intricate processes governing momentum/density transport and the emergence of zonal flows in the saturation of protoplanetary disks.}, archive = {J_ApJ}, author = {Chang-Chun Chen and Hui Li and P. H. Diamond and Shengtai Li}, doi = {10.3847/1538-4357/ad9a68}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {116}, shortjournal = {The Astrophys. J.}, title = {Zonal flow and self-regulating mechanism in a hydrodynamic disk}, volume = {982}, year = {2025}, }
• (2025). The origin of a preeruptive magnetic structure with significant nonneutralized electric current. ApJ, 982(2), 115. (www)

  @article{ , abstract = {The buildup of the preeruptive magnetic field configuration and the eruption onset mechanism are critical yet poorly understood in solar eruptions. Coronal structures like sigmoids and filaments have been identified as preeruptive magnetic structures; their associated preflare motions as well as preflare brightenings have been identified as precursor signatures, yet none of these definitively lead to eruptions, and the cause and effect is contentious. Most importantly, how the preeruptive coronal structure evolves with the photospheric magnetic field is elusive. Here we report the development of the photospheric nonneutralized electric current associated with the buildup of a preeruptive coronal structure observed as a bundle of hot low-lying coronal loops collectively taking a sigmoidal shape. The significant nonneutralized electric current appeared several hours ahead of the formation of the preeruptive structure. The buildup of the preeruptive structure in the corona was simultaneous with the gradual extension of the nonneutralized electric current in the photosphere. The synchronous evolution seemed to stop when intermittent brightening occurred along the preeruptive structure in the corona. The preflare brightening lasted for about 4 hr, with two ribbon-like structures matching the nonneutralized electric current. Eventually, the preeruptive structure evolved into a magnetic flux rope (MFR) and erupted. Quantitative measurements indicate that the significant nonneutralized electric current also flows through the footpoints of the erupting MFR, which are well identified by a pair of conjugate dimmings. The evolution of the photospheric nonneutralized electric current is demonstrated to signal the buildup of the preeruptive structure and the imminent eruption.}, archive = {J_ApJ}, author = {Wensi Wang and Rui Liu and Jiong Qiu and Jinhan Guo and Yuming Wang}, doi = {10.3847/1538-4357/adb7d8}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {115}, shortjournal = {The Astrophys. J.}, title = {The origin of a preeruptive magnetic structure with significant nonneutralized electric current}, volume = {982}, year = {2025}, }
• (2025). Magnetic activity evolution of solar-like stars. II. Sph–Ro evolution of kepler main-sequence targets. ApJ, 982(2), 114. (www)

  @article{ , abstract = {There is now a large sample of stars observed by the Kepler satellite with measured rotation periods and photometric activity index S ph . We use this data, in conjunction with stellar interiors models, to explore the interplay of magnetism, rotation, and convection. Stellar activity proxies other than S ph are correlated with the Rossby number, Ro, or ratio of rotation period to convective overturn timescale. We compute the latter using the Yale Rotating Evolution Code stellar models. We observe different S ph –Ro relationships for different stellar spectral types. Though the overall trend of decreasing magnetic activity versus Rossby number is recovered, we find a localized dip in S ph around Ro/Ro ⊙ ∼  0.3 for the G and K dwarfs. F dwarfs show little to no dependence of S ph on Rossby number due to their shallow convective zone, further accentuated as T eff increases. The dip in activity for the G and K dwarfs corresponds to the intermediate rotation period gap, suggesting that the dip in S ph could be associated with the redistribution of angular momentum between the core and convective envelope inside stars. For G-type stars, we observe enhanced magnetic activity above the solar Rossby number. Compared to other Sun-like stars with similar effective temperature and metallicity, we find that the Sun's current level of magnetic activity is comparable to its peers and lies near the transition to increasing magnetic activity at high Rossby number. We confirm that metal-rich stars have a systematically larger S ph level than metal-poor stars, which is likely a consequence of their deeper convective zones.}, archive = {J_ApJ}, author = {Savita Mathur and Ângela R. G. Santos and Zachary R. Claytor and Rafael A. García and Antoine Strugarek and Adam J. Finley and Quentin Noraz and Louis Amard and Paul G. Beck and Alfio Bonanno and Sylvain N. Breton and Allan S. Brun and Lyra Cao and Enrico Corsaro and Diego Godoy-Rivera and Stéphane Mathis and Dinil B. Palakkatharappil and Marc H. Pinsonneault and Jennifer van Saders}, doi = {10.3847/1538-4357/adb8cc}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {114}, shortjournal = {The Astrophys. J.}, title = {Magnetic activity evolution of solar-like stars. II. Sph–Ro evolution of kepler main-sequence targets}, volume = {982}, year = {2025}, }
• (2025). Accreting binary eccentricities follow predicted equilibrium values. ApJ, 982(2), 113. (www)

  @article{ , abstract = {We investigate observations of circumbinary disks (CBDs) to find evidence for an equilibrium eccentricity predicted by current binary accretion theory. Although stellar binary demographics in the Milky Way show no evidence for a preferred eccentricity for binary systems, we show that actively accreting systems lie on a predicted equilibrium eccentricity curve. We constrain our sample to only systems that have well-defined orbital parameters (e.g., eccentricity, mass ratio, inclination angle). We find observations are consistent with theory for stellar binaries that are aligned with the disk and that are separated enough that tidal circularization is negligible. This suggests that eccentricity in these systems evolves after the dissipation of the CBD, given the flat eccentricity distribution of binary systems in the Milky Way.}, archive = {J_ApJ}, author = {Allen R. Murray and Paul C. Duffell}, doi = {10.3847/1538-4357/adb96e}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {113}, shortjournal = {The Astrophys. J.}, title = {Accreting binary eccentricities follow predicted equilibrium values}, volume = {982}, year = {2025}, }
• (2025). A counterintuitive correlation between neutron star radii inferred from pulse modeling and surface emission beaming. ApJ, 982(2), 112. (www)

  @article{ , abstract = {Thermal X-ray emission from rotation-powered millisecond pulsars, shaped by gravitational lensing and the beaming of the surface radiation, provides critical insights into neutron star properties. This approach has been the focus of observations with the Neutron Star Interior Composition Explorer (NICER) mission. Using a semianalytic model to calculate pulse profiles, we investigate the effects of adopting incorrect beaming models on the inferred compactness of neutron stars. We demonstrate that assuming a more centrally peaked beaming pattern when fitting data from a more isotropic emitter leads to an underestimation of compactness in the case of two antipodal polar caps. We present a detailed analysis of this counterintuitive result, offering both qualitative insights and quantitative estimates. If the atmospheric heating in the millisecond pulsars observed with NICER is shallow, the inferred radii for these sources could be significantly overestimated, with important implications for neutron star structure and equation-of-state constraints.}, archive = {J_ApJ}, author = {Tong Zhao and Dimitrios Psaltis and Feryal Özel}, doi = {10.3847/1538-4357/adb9ea}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {112}, shortjournal = {The Astrophys. J.}, title = {A counterintuitive correlation between neutron star radii inferred from pulse modeling and surface emission beaming}, volume = {982}, year = {2025}, }
• (2025). Observational signatures of a previous dynamical instability in multi-planet M-dwarf systems. ApJ, 982(2), 111. (www)

  @article{ , abstract = {We identify observational signatures suggesting a history of dynamical instability in 26 out of 34 M-dwarf multi-planet systems containing no large planets. These systems may have primarily formed in a gas-rich environment, potentially hosted more planets, and were more compact. We extend previous simulations of the formation of the TRAPPIST-1 system to 100 Myr to test the stability of these systems without gas. We find that the absence of a strong mean motion resonance in the innermost planet pair and the absence of three-body resonances throughout the system are likely to result in the merging and ejection of planets after the gas disk disperses. The runs that experience such an instability tend to produce final systems with lower multiplicities, period ratios larger than two, increased orbital spacings, higher planetary angular momentum deficits, and slightly smaller mass ratios between adjacent planets. Remarkably, we find these same trends in the observations of M-dwarf multi-planet systems containing no large planets. Our work allows us to identify specific systems that may have experienced an instability, and it suggests that only  ∼25% of these systems formed in their current observed state, while most systems were likely more compact and multiplicitous earlier in time. Previous research indicates that planets that have experienced a late-stage giant impact may potentially be more habitable than those that did not. With this in mind, we suggest systems around M-dwarfs that contain period ratios larger than two be given priority in the search for habitable worlds.}, archive = {J_ApJ}, author = {Anna C. Childs and Alexa P. S. Hua and Rebecca G. Martin and Chao-Chin Yang and Aaron M. Geller}, doi = {10.3847/1538-4357/adbb53}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {111}, shortjournal = {The Astrophys. J.}, title = {Observational signatures of a previous dynamical instability in multi-planet M-dwarf systems}, volume = {982}, year = {2025}, }
• (2025). An agnostic approach to building empirical type ia supernova light curves: Evidence for intrinsic chromatic flux variation using nearby supernova factory data. ApJ, 982(2), 110. (www)

  @article{ , abstract = {We present a new empirical Type Ia supernova (SN Ia) model with three chromatic flux variation templates: one phase dependent and two phase independent. No underlying dust extinction model or patterns of intrinsic variability are assumed. Implemented with S tan and trained using spectrally binned Nearby Supernova Factory spectrophotometry, we examine this model's 2D, phase-independent flux variation space using two motivated basis representations. In both, the first phase-independent template captures variation that appears dust-like, while the second captures a combination of effectively intrinsic variability and second-order dust-like effects. We find that ≈13% of the modeled phase-independent flux variance is not dust-like. Previous empirical SN Ia models either assume an effective dust extinction recipe in their architecture, or only allow for a single mode of phase-independent variation. The presented results demonstrate such an approach may be insufficient, because it could "leak" noticeable intrinsic variation into phase-independent templates.}, archive = {J_ApJ}, author = {Jared Hand and A. G. Kim and G. Aldering and P. Antilogus and C. Aragon and S. Bailey and C. Baltay and S. Bongard and K. Boone and C. Buton and Y. Copin and S. Dixon and D. Fouchez and E. Gangler and R. Gupta and B. Hayden and W. Hillebrandt and Mitchell Karmen and M. Kowalski and D. Küsters and P.-F. Léget and F. Mondon and J. Nordin and R. Pain and E. Pecontal and R. Pereira and S. Perlmutter and K. A. Ponder and D. Rabinowitz and M. Rigault and D. Rubin and K. Runge and C. Saunders and N. Suzuki and C. Tao and S. Taubenberger and R. C. Thomas and M. Vincenzi and (The Nearby Supernova Factory)}, doi = {10.3847/1538-4357/ad9f32}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {110}, shortjournal = {The Astrophys. J.}, title = {An agnostic approach to building empirical type ia supernova light curves: Evidence for intrinsic chromatic flux variation using nearby supernova factory data}, volume = {982}, year = {2025}, }
• (2025). Spatial and chemical complexity in the W75N star-forming region. ApJ, 982(2), 109. (www)

  @article{ , abstract = {We present the analysis of NOEMA interferometric observations of the high-mass star-forming region W75N(B) with a focus on molecular composition and distribution of prebiotic molecules in the source's multiple cores. Over 20 molecules are identified across the region, with many being fit for column density, rotational temperature, spectral line FWHM, and v lsr . This work includes the first known detection and initial analysis of complex organic molecules in the MM2 and MM3 regions. Furthermore, parameter maps were created from the six molecules that were well fit across multiple regions. The molecular emission was imaged and correlated across different molecules and the continuum to reveal structural features. From the spatial and spectral analysis of the MM1 region, these results concur with those from other studies showing that there is a difference in chemical composition between the MM1a and MM1b regions, with sulfur-bearing molecules tracing MM1a and organic molecules tracing MM1b. The molecular emission imaged toward the MM3 region reveals two peaks, possibly indicating the presence of multiple young stellar objects. These results provide detailed quantitative information about the physical parameters and distributions of molecules in this source. Additionally, these results are part of a follow-up of a single-dish survey of multiple star-forming regions and are discussed in this context.}, archive = {J_ApJ}, author = {Morgan M. Giese and Will E. Thompson and Dariusz C. Lis and Susanna L. Widicus Weaver}, doi = {10.3847/1538-4357/adb62d}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {109}, shortjournal = {The Astrophys. J.}, title = {Spatial and chemical complexity in the W75N star-forming region}, volume = {982}, year = {2025}, }
• (2025). SDSS-IV MaNGA: Spectroscopic probes of neutral gas in nearby galaxies. ApJ, 982(2), 108. (www)

  @article{ , abstract = {Cool, dusty interstellar material plays an important role in the chemical evolution of galaxies. We present an analysis of this material across galaxy type through a spatially resolved spectral stacking analysis of galaxies from the MaNGA survey. With stellar population synthesis, we isolate neutral gas signals from resonance lines, comparing outcomes across model types, galactic geometry, and host stellar mass and age. We find that both synthetic and empirical models fail to capture the range of galactic chemical abundances. There is also notable Na i contamination from the Galaxy's interstellar medium (ISM) in the MILES empirical stellar library. We are unable to reliably determine the column density of the gas due to the accuracy of absorption measurements, but differential analysis across radius and inclination reveals consistent and significant path-length dependent absorption in the equivalent width of Na i . We note similar but lesser trends in a narrow Ca ii index. We find no trends in Ca i or in a broad Ca ii index, indicating its ISM insensitivity and providing evidence in favor of its utility in determining the age and chemical content of stellar populations. Our data shows there is a cool ISM component in most external galaxies with D n (4000) < 1.7 that can be traced by Na i . Lastly, we caution that the characterization of gas kinematics traced by Na i in such low-resolution spectra is subject to systematic effects due to the chosen approach to stellar population modeling.}, archive = {J_ApJ}, author = {Camilo Machuca and Matthew A. Bershady and Kate H. R. Rubin and Eric Wilcots}, doi = {10.3847/1538-4357/adb72d}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {108}, shortjournal = {The Astrophys. J.}, title = {SDSS-IV MaNGA: Spectroscopic probes of neutral gas in nearby galaxies}, volume = {982}, year = {2025}, }
• (2025). Single-pulse morphology of PSR j1935+1616 (B1933+16) based on archival data from FAST. ApJ, 982(2), 107. (www)

  @article{ , abstract = {We utilized archive data from the Five-hundred-meter Aperture Spherical Radio Telescope (FAST) to analyze the single-pulse profile morphology of PSR J1935+1616 (B1933+16). The results show that PSR J1935+1616 exhibits significant micropulses as well as various changes in single-pulse profile morphology. In the FAST archive data, a total of 969 single pulses with microstructure were identified, accounting for 9.69% of the total pulse sample, with characteristic widths of 127.6{3}_{-46.25}^{+70.74} μ s. About half of these pulses display quasiperiodic micropulses, with a periodicity of 231.77 ± 9.90 μ s. Among the 520 single pulses with quasiperiodic microstructure, 208 also exhibit quasiperiodicity in circular polarization, with a characteristic period of 244.7{0}_{-21.05}^{+45.66}\,\mu \,\rm{s}\, . The micropulse characteristic width in circular polarization is 106.52 ± 46.14 μ s. Compared to normal pulses, the relative energy ( E /< E >) of a single pulse with microstructure follows a double-Gaussian distribution, while those of normal pulses follow a single-Gaussian distribution. Based on the intensity of the leading and trailing components in the single-pulse profile morphology of PSR J1935+1616, we classified the pulses into four morphological modes (A, B, C, and D). The relative energy distribution of pulses in Mode A is significantly different from the others, following a double-Gaussian distribution, while the relative energy distributions in Modes B, C, and D follow a single-Gaussian distribution. Our study also suggests a possible correlation between micropulses and single-pulse profile morphology. Single pulses with micropulses are most likely to occur in Mode A, while their occurrence is least likely in Mode D.}, archive = {J_ApJ}, author = {R. W. Tian and R. S. Zhao and Marilyn Cruces and H. Liu and D. Li and P. Wang and C. H. Niu and Biping Gong and C. C. Miao and X. Zhu and H. W. Xu and W. L. Li and S. D. Wang and Z. F. Tu and Q. J. Zhi and S. J. Dang and L. H. Shang and S. Xiao}, doi = {10.3847/1538-4357/adb7cd}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {107}, shortjournal = {The Astrophys. J.}, title = {Single-pulse morphology of PSR j1935+1616 (B1933+16) based on archival data from FAST}, volume = {982}, year = {2025}, }
• (2025). Rising from the ashes: A metallicity-dependent star formation gap splits the milky way’s α sequences. ApJ, 982(2), 106. (www)

  @article{ , abstract = {The elemental abundance distribution of stars encodes the history of the gas-phase abundance in the Milky Way. Without a large, unbiased sample of highly precise stellar ages, the exact timing and nature of this history must be inferred from the abundances. In the two-dimensional plane of [ α /Fe]–[Fe/H], it is now clear that two separate populations exist—the low- α and high- α sequences. We propose that a brief (∼300 Myr) halt in star formation within a narrow metallicity bin can lead to a bimodal [ α /Fe] distribution at that metallicity, assuming a rapidly declining gas phase [ α /Fe]. Using simulations of an idealized setup of a high- z galaxy merger, we show that the merger with the Gaia-Sausage-Enceladus satellite at z ∼ 2 is one possible way to trigger such a gap in the Milky Way. This mechanism may also operate in nonmerger scenarios. We predict a ∼300 Myr gap in stellar ages at a fixed [Fe/H] where the α bimodality is prominent ([Fe/H] ≲ −0.2).}, archive = {J_ApJ}, author = {Angus Beane}, doi = {10.3847/1538-4357/adb83e}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {106}, shortjournal = {The Astrophys. J.}, title = {Rising from the ashes: A metallicity-dependent star formation gap splits the milky way’s α sequences}, volume = {982}, year = {2025}, }
• (2025). The discovery of rapid polarization angle variation during the 2022 outburst of XTE j1701-462. ApJ, 982(2), 105. (www)

  @article{ , abstract = {The geometry of the Comptonization corona in neutron star low-mass X-ray binaries is still unclear. We conducted time-resolved polarimetric analysis of the archival observations of XTE J1701–462 obtained with the Imaging X-ray Polarimeter Explorer during its 2022 outburst and found that the polarization angle (PA) varied significantly with time when the source was in the normal branch, with 67 ∘ ± 8 ∘ in the first epoch, −34 ∘ ± 8 ∘ in the second, and −58 ∘ ± 8 ∘ in the third, last epoch. Meanwhile, the polarization degree remained constant at around 2%, above the minimum detectable polarization at the 99% confidence level (MDP 99 ). The rapid PA variation causes depolarization in the time-averaged data, resulting in a nondetection as reported in the literature. The rapid (intraday) PA variation may suggest that there is a fast transformation of the corona geometry, likely switching from a slab geometry with enhanced disk emission and reflection, to a more vertically extended spreading layer geometry.}, archive = {J_ApJ}, author = {Qing-Chang Zhao and Hong Li and Lian Tao and Hua Feng}, doi = {10.3847/1538-4357/adb8cf}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {105}, shortjournal = {The Astrophys. J.}, title = {The discovery of rapid polarization angle variation during the 2022 outburst of XTE j1701-462}, volume = {982}, year = {2025}, }
• (2025). High-frequency coronal alfvénic waves observed with DKIST/Cryo-NIRSP. ApJ, 982(2), 104. (www)

  @article{ , abstract = {The presence and nature of low-frequency (0.1–10 mHz) Alfvénic waves in the corona have been established over the past decade, with many of these results coming from coronagraphic observations of the infrared Fe xiii line. The Cryo-NIRSP instrument situated at DKIST has recently begun acquiring science-quality data of the same Fe xiii line, with at least a factor of 9 improvement in spatial resolution, a factor of 30 increase in temporal resolution, and an increase in signal-to-noise ratio, when compared to the majority of previously available data. Here we present an analysis of 1 s cadence sit-and-stare data from Cryo-NIRSP, examining the Doppler velocity fluctuations associated with the Fe xiii 1074 nm coronal line. We are able to confirm previous results of Alfvénic waves in the corona and explore a new frequency regime. The data reveal that the power-law behavior of the Doppler velocity power spectrum extends to higher frequencies. This result appears to challenge some models of photospheric-driven Alfvénic waves that predict a lack of high-frequency wave power in the corona owing to strong chromospheric damping. Moreover, the high-frequency waves do not transport as much energy as their low-frequency counterparts, with less time-averaged energy per frequency interval. We are also able to confirm the incompressible nature of the fluctuations with little coherence between the line amplitude and Doppler velocity time series.}, archive = {J_ApJ}, author = {Richard J. Morton and Momchil Molnar and Steven R. Cranmer and Thomas A. Schad}, doi = {10.3847/1538-4357/adb8df}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {104}, shortjournal = {The Astrophys. J.}, title = {High-frequency coronal alfvénic waves observed with DKIST/Cryo-NIRSP}, volume = {982}, year = {2025}, }
• (2025). Forecasting of the time-dependent fluxes of antiprotons in the AMS-02 era. ApJ, 982(2), 103. (www)

  @article{ , abstract = {The spectra of Galactic cosmic rays (GCRs) contain crucial information about their origin and propagation through the interstellar medium. When GCRs reach Earth, they are significantly influenced by the solar wind and the heliospheric magnetic field, a phenomenon known as solar modulation. This effect introduces time-dependent variations in GCR fluxes. The AMS-02 experiment has released time-dependent flux data for protons, electrons, and positrons, revealing clear correlations with solar modulation. Studies suggest that cosmic rays with the same charge, such as protons and helium nuclei, exhibit similar or the same solar modulation parameters. In this work, we derive the local interstellar spectrum (LIS) for protons and positrons under the assumption of a common solar modulation potential, using data from Voyager 1 and a 7 yr average from AMS-02. Similarly, the LIS for antiprotons and electrons is derived by assuming they are governed by a separate solar modulation potential. We demonstrate that the time-dependent fluxes of positrons and protons can be accurately modeled using the same set of solar modulation parameters within a modified force-field approximation framework. Based on this, we predict the time-dependent fluxes of antiprotons using the corresponding electron flux data.}, archive = {J_ApJ}, author = {Cheng-Rui Zhu and Kai-Kai Duan}, doi = {10.3847/1538-4357/adbaf1}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {103}, shortjournal = {The Astrophys. J.}, title = {Forecasting of the time-dependent fluxes of antiprotons in the AMS-02 era}, volume = {982}, year = {2025}, }
• (2025). No glitch in the matrix: Robust reconstruction of gravitational wave signals under noise artifacts. ApJ, 982(2), 102. (www)

  @article{ , abstract = {Gravitational wave (GW) observations by ground-based detectors such as LIGO and Virgo have transformed astrophysics, enabling the study of compact binary systems and their mergers. However, transient noise artifacts, or "glitches," pose a significant challenge, often obscuring or mimicking signals and complicating their analysis. In this work, we extend the Attention-boosted Waveform Reconstruction network ( AWaRe ) to address glitch mitigation, demonstrating its robustness in reconstructing waveforms in the presence of real glitches from LIGO's third observing run. Without requiring explicit training on glitches, AWaRe accurately isolates GW signals from data contaminated by glitches spanning a wide range of amplitudes and morphologies. We evaluate this capability by investigating the events GW191109 and GW200129, which exhibit strong evidence of antialigned spins and spin precession, respectively, but may be adversely affected by data quality issues. We find that, regardless of the potential presence of glitches in the data, AWaRe reconstructs both waveforms with high accuracy. Additionally, we perform a systematic study of AWaRe 's performance on a simulated catalog of injected waveforms in real LIGO glitches and obtain reliable reconstructions of the waveforms. By subtracting the AWaRe reconstructions from the data, we show that the resulting residuals closely align with the background noise that the waveforms were injected in. The robustness of AWaRe in mitigating glitches, despite being trained exclusively on GW signals and not explicitly on glitches, highlights its potential as a powerful tool for improving the reliability of searches and characterizing noise artifacts.}, archive = {J_ApJ}, author = {Chayan Chatterjee and Karan Jani}, doi = {10.3847/1538-4357/adbb66}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {102}, shortjournal = {The Astrophys. J.}, title = {No glitch in the matrix: Robust reconstruction of gravitational wave signals under noise artifacts}, volume = {982}, year = {2025}, }
• (2025). Plasma instability evolution and particle heating in the foot region of perpendicular shocks in young supernova remnants. ApJ, 982(2), 101. (www)

  @article{ , abstract = {Particle acceleration from collisionless shocks is a key mechanism in the generation of cosmic rays. In particular, shocks in young supernova remnants (SNRs) are considered to be a major source of galactic cosmic rays. This study investigates the early-stage plasma instability evolution and subsequent electron and ion heating in the foot region of high-Mach-number perpendicular shocks in young SNRs, using 2D particle-in-cell simulations. Unlike previous simulations that cover larger regions of the shock structure—including the downstream, shock, and upstream regions—our simulations are local, limited to the shock transition region, and focus on practical parameters with a nonrelativistic shock velocity ( v ≈ 0.02 c ) and the standard mass ratio between protons and electrons. We examined scenarios with and without the presence of return protons, and our results reveal that the Buneman instability, followed by the ion two-stream instability, dominates the early electron-heating process. We observed long-lasting ion heating in the case without return protons and note that the Weibel instability did not emerge within the simulation time frame. These findings enhance the understanding of plasma behavior in young SNR shocks and suggest that local simulations with practical parameters are crucial for exploring electron-heating mechanisms, while also highlighting the conditions under which the Weibel instability may or may not emerge.}, archive = {J_ApJ}, author = {K. F. F. Law and S. Fujioka and Y. Ohira}, doi = {10.3847/1538-4357/adb629}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {101}, shortjournal = {The Astrophys. J.}, title = {Plasma instability evolution and particle heating in the foot region of perpendicular shocks in young supernova remnants}, volume = {982}, year = {2025}, }
• (2025). Carving out the inner edge of the period ratio distribution through giant impacts. ApJ, 982(2), 100. (www)

  @article{ , abstract = {The distribution of orbital period ratios between adjacent observed exoplanets is approximately uniform, but exhibits a strong falloff toward close orbital separations. We show that this falloff can be explained through past dynamical instabilities carving out the period ratio distribution. Our suite of numerical experiments would have required ∼3 million CPU hr through direct N-body integrations, but was achieved with only  ≈50 CPU hr by removing unstable configurations using the Stability of Planetary Orbital Configurations Klassifier machine learning model. This highlights the role of dynamical instabilities in shaping the observed exoplanet population, and shows that the inner part of the period ratio distribution provides a valuable observational anchor on the giant impact phase of planet formation.}, archive = {J_ApJ}, author = {Kaitlyn Chen and Oswaldo Cardenas and Brandon Bonifacio and Nikolas Hall and Rori Kang and Daniel Tamayo}, doi = {10.3847/1538-4357/adae8a}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {100}, shortjournal = {The Astrophys. J.}, title = {Carving out the inner edge of the period ratio distribution through giant impacts}, volume = {982}, year = {2025}, }
• (2025). The direct measurement of gravitational potential decay rate at cosmological scales. II. improved dark energy constraint from z ≤ 1.4. ApJ, 982(2), 99. (www)

  @article{ , abstract = {The gravitational potential decay rate (DR) is caused by the cosmic acceleration of the Universe, providing a direct probe into the existence of dark energy (DE). We present measurements of DR and explore its implications for DE models using the DR9 galaxy catalog of the Dark Energy Spectroscopic Instrument (DESI) imaging surveys and the Planck cosmic microwave background maps. Our analysis includes six redshift bins within the range of 0.2 ≤ z < 1.4 and achieves a total significance of 3.1 σ , extending the DR measurements to a much higher redshift compared to Dong et al., which focused on 0.2 ≤ z < 0.8. Other improvements involve addressing potential systematics in the DR-related measurements of correlation functions, including imaging systematics and magnification bias. We explore the constraining power of DR on both the w CDM model and the w 0 w a CDM model. We find that the addition of DR can significantly improve the DE constraints, over Sloan Digital Sky Survey baryon acoustic oscillation (BAO) data alone or the PantheonPlus supernovae (SNe) compilation alone, although it shows only a modest improvement for DESI BAO. In the w CDM model, all three probes—DR, DESI BAO, and SNe—favor w = −1. For the w 0 w a CDM, while DESI BAO prefers w 0 > −1 and w a < 0, the SNe Ia and DR data constrain {w}_{0}=-0.9{4}_{-0.13}^{+0.11} and {w}_{a}=-0.2{2}_{-0.97}^{+0.57} . Namely, SNe Ia and DR data have no preference on dynamical DE over Λ.}, archive = {J_ApJ}, author = {Fuyu Dong and Pengjie Zhang and Haojie Xu and Jian Qin}, doi = {10.3847/1538-4357/adb585}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {99}, shortjournal = {The Astrophys. J.}, title = {The direct measurement of gravitational potential decay rate at cosmological scales. II. improved dark energy constraint from z ≤ 1.4}, volume = {982}, year = {2025}, }
• (2025). Short-term balmer line emission variability in m dwarfs. ApJ, 982(2), 98. (www)

  @article{ , abstract = {M dwarfs make up the majority of stars, offering an avenue for discovering exoplanets due to their smaller sizes. However, their magnetic activity poses challenges for exoplanet detection, characterization, and planetary habitability. Understanding their magnetic activity, including surface starspots and internal dynamos, is crucial for exoplanet research. In this study, we present short-term variability in four Balmer emission lines, H α , H β , H γ , and H δ , for a sample of 77 M dwarfs of varying spectral types and binarity. Stars were observed using the MDM Observatory's Ohio State Multi-Object Spectrograph on the 2.4 m telescope and the Modular Spectrograph on the 1.3 m telescope. These data are combined with TESS photometry to explore the connection between spectroscopic and photometric variability. We observe sporadic short-term variability in Balmer lines for some stars, on a timescale ≳15 min, but much shorter than the stellar rotation period. We calculate periods for stars lacking those measurements, reevaluate the amplitude ( R var )–activity relation for the H α line from A. Garcìa Soto et al., and extend our analysis to the H β , H γ , and H δ lines, which indicates that the relation becomes increasingly dispersed for higher-order Balmer lines. This is consistent with increased intrinsic variability from lower- to higher-order lines. Additionally, we compute the Balmer decrement, using H β as the fiducial, for stars where we could measure H γ and/or H δ . The Balmer decrement can show distinct patterns during white-light flares, with significant differences even for the same star. We also find evidence for dark spots on TIC 283866910.}, archive = {J_ApJ}, author = {Aylin García Soto and Girish M. Duvvuri and Elisabeth R. Newton and Ward S. Howard and Alejandro Núñez and Stephanie T. Douglas}, doi = {10.3847/1538-4357/adb615}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {98}, shortjournal = {The Astrophys. J.}, title = {Short-term balmer line emission variability in m dwarfs}, volume = {982}, year = {2025}, }
• (2025). Linking analytic light-curve models to physical properties of kilonovae. ApJ, 982(2), 97. (www)

  @article{ , abstract = {In binary neutron star mergers, lanthanide-rich dynamical ejecta and lanthanide-poor postmerger ejecta have often been linked to red and blue kilonova emission, respectively. However, analytic light-curve modeling of kilonovae often results in ejecta parameters that are at odds with such expectations. To investigate the physical meaning of the derived parameters, we perform analytic modeling of the kilonova light curves calculated with realistic multidimensional radiative transfer based on numerical relativity simulations. Our fiducial simulations adopt a faster-moving, less massive dynamical ejecta and slower-moving, more massive postmerger ejecta. The results of analytic modeling, however, show that the inferred "red" component is more massive and slower, while the "blue" component is less massive and faster, as also inferred for GW170817/AT 2017gfo. This suggests that the parameters derived from light-curve modeling with an analytic model do not represent the true configuration of the kilonova ejecta. We demonstrate that the postmerger ejecta contributes to both blue and red emissions: the emission from the postmerger ejecta is absorbed and reprocessed to red emission by the dynamical ejecta with a higher lanthanide fraction. Our results caution against separately discussing the origins of the red and blue components derived from the analytic models. Despite the challenges in the parameter estimation, we show that the estimate of the total ejecta mass is rather robust within a factor of a few, reflecting the total luminosity output. To derive the reliable total ejecta mass, multiepoch observations in near-infrared wavelengths near their light-curve peaks are important.}, archive = {J_ApJ}, author = {Ayari Kitamura and Kyohei Kawaguchi and Masaomi Tanaka and Sho Fujibayashi}, doi = {10.3847/1538-4357/adb62c}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {97}, shortjournal = {The Astrophys. J.}, title = {Linking analytic light-curve models to physical properties of kilonovae}, volume = {982}, year = {2025}, }
• (2025). Recovering ion distribution functions. i. slepian reconstruction of velocity distribution functions from MMS and solar orbiter. ApJ, 982(2), 96. (www)

  @article{ , abstract = {Plasma velocity distribution functions (VDFs) constitute a fundamental observation of numerous operational and future missions. An efficient parameterization of VDFs is crucial for (1) preserving enough information to investigate macroscopic moments along with kinetic effects, (2) producing smooth distributions whereby it is possible to perform derivatives in phase space to support numerical solvers, and (3) economic data management and its storage. Previous studies have used spherical harmonics as an efficient basis for representing electron VDFs. In this paper, we present a novel algorithm targeted toward decomposing ion VDFs measured by electrostatic analyzers on board Magnetospheric Multiscale (MMS) Mission and Solar Orbiter (SolO) spacecraft. We use Slepian functions, custom-designed bases providing compact support in phase space, initially developed in information theory and later used for terrestrial and planetary applications. In this paper, we choose well-studied, well-measured, and complex intervals from MMS and SolO containing a range of simpler gyrotropic and agyrotropic distributions to benchmark the robustness of our reconstruction method. We demonstrate the advantages of using Slepian functions over spherical harmonics for solar wind plasma distributions. We also demonstrate that our choice of basis representation efficiently preserves phase space complexities of a 3D agyrotropic distribution function. This algorithm shown in this study will be extended to Parker Solar Probe and future missions such as Helioswarm.}, archive = {J_ApJ}, author = {Srijan Bharati Das and Michael Terres}, doi = {10.3847/1538-4357/adb6a0}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {96}, shortjournal = {The Astrophys. J.}, title = {Recovering ion distribution functions. i. slepian reconstruction of velocity distribution functions from MMS and solar orbiter}, volume = {982}, year = {2025}, }
• (2025). ULX collimation by outflows in moderately magnetized neutron stars. ApJ, 982(2), 95. (www)

  @article{ , abstract = {We perform radiative magnetohydrodynamics simulations in general relativity of super-Eddington disk accretion onto neutron stars endowed with a magnetic dipole corresponding to surface strengths not exceeding 100 Giga-Gauss. Accretion is found to power strong outflows that collimate the emergent radiation of the accretion columns, leading to apparent radiative luminosities of ∼100 Eddington, when the true luminosity is a few Eddington units. Surprisingly, the collimation cone/angle widens with increasing magnetic field. Thus, in our simulations the apparent luminosity of the neutron star is substantially larger for the weaker magnetic fields (10 10 G) than for the stronger ones (10 11 G). We conclude that a super-Eddington accreting neutron star with dipole magnetic field on the order of 10 10 G is the most likely source of ultraluminous X-rays.}, archive = {J_ApJ}, author = {Fatemeh Kayanikhoo and Włodek Kluźniak and Miljenko Čemeljić}, doi = {10.3847/1538-4357/adb714}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {95}, shortjournal = {The Astrophys. J.}, title = {ULX collimation by outflows in moderately magnetized neutron stars}, volume = {982}, year = {2025}, }
• (2025). Prospects for observing astrophysical transients with gigaelectronvolt neutrinos. ApJ, 982(2), 94. (www)

  @article{ , abstract = {Although Cherenkov detectors of high-energy neutrinos in ice and water are often optimized to detect teraelectronvolt–petaelectronvolt neutrinos, they may also be sensitive to transient neutrino sources in the 1–100 GeV energy range. A wide variety of transient sources have been predicted to emit gigaelectronvolt neutrinos. In light of the upcoming IceCube Upgrade, which will extend the IceCube detector's sensitivity down to a few gigaelectronvolts, as well as improve its angular resolution, we survey a variety of transient-source models and compare their predicted neutrino fluences to detector sensitivities, in particular those of IceCube-DeepCore and the IceCube Upgrade. We consider ranges of neutrino fluence from transients powered by nonrelativistic shocks, such as novae, supernovae, fast blue optical transients, and tidal disruption events. We also consider fast radio bursts and relativistic outflows of high- and low-luminosity gamma-ray bursts. Our study sheds light on the prospects of observing gigaelectronvolt transients with existing and upcoming neutrino facilities.}, archive = {J_ApJ}, author = {Angelina Partenheimer and Jessie Thwaites and K. Fang and Justin Vandenbroucke and Brian D. Metzger}, doi = {10.3847/1538-4357/adb716}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {94}, shortjournal = {The Astrophys. J.}, title = {Prospects for observing astrophysical transients with gigaelectronvolt neutrinos}, volume = {982}, year = {2025}, }
• (2025). Toward multienergy neutrino astronomy: Diagnosing enhanced circumstellar material around stripped-envelope supernovae. ApJ, 982(2), 93. (www)

  @article{ , abstract = {A novel approach is proposed to reveal a secret birth of enhanced circumstellar material (CSM) surrounding a collapsing massive star using neutrinos as a unique probe. In this scheme, nonthermal TeV-scale neutrinos produced in ejecta–CSM interactions are tied with thermal MeV neutrinos emitted from a pre-explosion burning process, based on a scenario that CSM had been formed via the presupernova activity. Taking a representative model of the presupernova neutrinos, the spectrum and light curve of the corresponding high-energy CSM neutrinos are calculated at multiple mass-loss efficiencies, which are considered as a systematic uncertainty. In addition, as a part of the method demonstration, the detected event rates along time at JUNO and IceCube, as representative detectors, are estimated for the presupernova and CSM neutrinos, respectively, and are compared with the expected background rate at each detector. The presented method is found to be reasonably applicable for the range up to ∼1 kpc and even farther with future experimental efforts. The potentialities of other neutrino detectors, such as SK-Gd, Hyper-Kamiokande, and KM3NeT, are also discussed. This is a pioneering work of performing astrophysics with neutrinos from diverse energy regimes, initiating multienergy neutrino astronomy in the forthcoming era where next-generation large-scale neutrino telescopes are operating.}, archive = {J_ApJ}, author = {Ryo Sawada and Yosuke Ashida}, doi = {10.3847/1538-4357/adb721}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {93}, shortjournal = {The Astrophys. J.}, title = {Toward multienergy neutrino astronomy: Diagnosing enhanced circumstellar material around stripped-envelope supernovae}, volume = {982}, year = {2025}, }
• (2025). An analytical galactic chemical evolution model with gas inflow and a terminal wind. ApJ, 982(2), 92. (www)

  @article{ , abstract = {We present a new analytical galactic chemical evolution (GCE) model with gas inflow, internally caused outflow, and extra gas loss after a period of time. The latter mimics the ram pressure stripping of a dwarf satellite galaxy near the pericenter of its orbit around a host galaxy. The new model is called Inflow with Ram Pressure Stripping (IRPS). We fit the α -element ([ α /H]) distributions of the Draco, Sculptor, Fornax, Leo II, Leo I, and And XVIII dwarf spheroidal galaxies. We compared the best fits of IRPS with four other GCE models. The IRPS fits half of the galaxies in our set better than the Leaky Box, Pre-enriched, Accretion, and RPS models. Unlike previous models, none of the IRPS model parameters—not even the effective yield—correlate with galaxy properties, like luminosity. One of the IRPS parameters is the α -abundance at which stripping began. That parameter can override the effective yield in determining the galaxy's mean α -abundance.}, archive = {J_ApJ}, author = {Kateryna A. Kvasova and Evan N. Kirby}, doi = {10.3847/1538-4357/adb729}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {92}, shortjournal = {The Astrophys. J.}, title = {An analytical galactic chemical evolution model with gas inflow and a terminal wind}, volume = {982}, year = {2025}, }
• (2025). A new reaction rate of the 27Al(p,γ)28Si reaction based on indirect low-energy cross-section measurements. ApJ, 982(2), 91. (www)

  @article{ , abstract = {The Mg–Al cycle is characteristic of the high-temperature ( T ∼ 0.055 GK) H-burning of evolved stars and their nucleosynthesis. A proper comprehension of this reaction network can help in solving debated questions such as the occurrence of anticorrelation in Mg–Al abundances in globular clusters. Recent high-resolution surveys have shown that such an anticorrelation may hide the existence of multiple stellar populations and that the relative abundances of Mg isotopes may not be correlated with Al. Proton-induced reactions on 27 Al play a key role in this respect, in particular the interplay between the ( p , α ) and ( p , γ ) channels, determining the closure (or not) of the Mg–Al cycle. Presently, the situation is still debated owing to the large uncertainty affecting existing experimental nuclear data. A recent indirect measurement indicates a further reduction in the 27 Al( p , α ) 24 Mg reaction rate with respect to the ones commonly adopted in astrophysical models. In the present work, we update the 27 Al(p, γ ) 28 Si reaction rate based on the same indirect measurement results. In the case of AGB stars experiencing hot bottom burning, the revised rate would lead to a ∼35% increase in 27 Al abundance with respect to what is presently foreseen, with interesting astrophysical consequences.}, archive = {J_ApJ}, author = {M. La Cognata and S. Palmerini and F. Dell’Agli and P. Ventura and P. Adsley and R. Alba and S. Cherubini and M. Costa and A. Di Pietro and P. Figuera and G. L. Guardo and M. Gulino and F. Hammache and M. La Commara and L. Lamia and D. Lattuada and C. Maiolino and M. Mazzocco and A. Oliva and R. G. Pizzone and P. M. Prajapati and G. G. Rapisarda and S. Romano and D. Santonocito and M. L. Sergi and R. Spartá and A. Tumino}, doi = {10.3847/1538-4357/adb7e4}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {91}, shortjournal = {The Astrophys. J.}, title = {A new reaction rate of the 27Al(p,γ)28Si reaction based on indirect low-energy cross-section measurements}, volume = {982}, year = {2025}, }
• (2025). Evolution of extremely soft binaries in dense star clusters: On the jupiter mass binary objects. ApJ, 982(2), 90. (www)

  @article{ , abstract = {Star-forming regions, characterized by dense environments, experience frequent encounters that significantly influence binary systems, leading to their hardening, softening, or ionization. We extend the Hut and Bahcall formalism to derive an analytical expression for the ionization cross section in extreme mass ratio binary systems, allowing us to investigate the orbital evolution and population dynamics of binary planets and binary brown dwarfs in star clusters, while considering ongoing binary system formation. Our findings reveal that for low-mass soft binaries, the semimajor axis distribution asymptotes to a universal power law between  ∝ a −8/3 and  ∝ a −5/3 over the derived ionization timescale. We also discuss the implications of our results for the candidate Jupiter-mass binary objects putatively reported in the Trapezium cluster. We demonstrate that if their existence is verified, they likely form continuously with a spectrum proportional to a 1 , aligning better with the ejection mechanism than with the in situ formation mechanism, which predicts a distribution roughly proportional to a −1 . However, this implies an impractically high ejection formation rate. Alternatively, if these objects are binary brown dwarfs, continuous in situ formation (∝ a −1 ) with an initial minimal semimajor axis around 20 au and a formation rate of 100 Myr −1 plausibly matches the observed number of single objects, binary number, binary fraction, and semimajor axis distribution.}, archive = {J_ApJ}, author = {Yihan Wang and Rosalba Perna and Zhaohuan Zhu and Douglas N. C. Lin}, doi = {10.3847/1538-4357/adb8e9}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {90}, shortjournal = {The Astrophys. J.}, title = {Evolution of extremely soft binaries in dense star clusters: On the jupiter mass binary objects}, volume = {982}, year = {2025}, }
• (2025). Hydrodynamic predictions for the next outburst of t coronae borealis: It will be the brightest classical or recurrent nova ever observed in X-rays*. ApJ, 982(2), 89. (www)

  @article{ , abstract = {T Coronae Borealis (TCrB) is a recurrent nova with recorded outbursts in 1866 and 1946 and possible outbursts in 1217 and 1787. It is predicted to explode again in 2025 or 2026 based on multiple observational studies. The system consists of a massive ( M wd ≳ 1.35 M ⊙ ) white dwarf (WD) and a red giant (M3–M4 III). We have performed 1D hydrodynamic simulations with NOVA to predict the behavior of the next outburst. These simulations consist of a range of mass accretion rates onto ∼1.35 M ⊙ WDs, designed to bound the conditions necessary to achieve ignition of an explosion after an ≈80 yr interoutburst period. We have used both carbon–oxygen and oxygen–neon initial compositions, in order to include the possible ejecta abundances to be measured in the observations of the next outburst. As the WD in the TCrB system is observed to be massive, theoretical predictions reported here imply that the WD is growing in mass as a consequence of the thermonuclear runaway. Therefore, the secular evolution of the WD may allow it to approach the Chandrasekhar limit and either explode as a Type Ia supernova or undergo accretion-induced collapse, depending on its underlying composition. We have followed the evolution of just the WD, after removing the ejected matter from the surface layers. Our intent is to illuminate the mystery of the unique, second maximum in the two well-observed outbursts and we have found conditions that bracket the predictions.}, archive = {J_ApJ}, author = {S. Starrfield and M. Bose and C. E. Woodward and C. Iliadis and W. R. Hix and A. Evans and G. Shaw and D. P. K. Banerjee and T. Liimets and K. L. Page and T. R. Geballe and I. Ilyin and I. Perron and R. M. Wagner}, doi = {10.3847/1538-4357/adb8ed}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {89}, shortjournal = {The Astrophys. J.}, title = {Hydrodynamic predictions for the next outburst of t coronae borealis: It will be the brightest classical or recurrent nova ever observed in X-rays*}, volume = {982}, year = {2025}, }
• (2025). Compton scattering of thermal disk radiation with black hole disk winds. ApJ, 982(2), 88. (www)

  @article{ , abstract = {Galactic black hole (BH) X-ray binaries (XRBs) are known to exhibit episodic outbursts, during which accretion and spectral mode distinctively transition between low/hard and high/soft state. X-ray observations during high/soft state occasionally reveal a pronounced presence of a powerful disk wind in these systems. However, it is unexplored to date how such winds may influence disk emission in that regime. In this work, we consider an observational implication by Compton scattering of thermal disk radiation due to accretion disk winds by performing multidimensional Monte Carlo simulations in the context of a stratified wind of large solid angle launched over a large radial extent of the disk. The Compton-scattered thermal disk spectrum is computed for a different wind property, i.e., wind density and its radial gradient. We find that the intrinsic disk radiation can be significantly down-scattered by winds of moderate-to-high density to the extent that the transmitted spectrum can substantially deviate from the conventional multicolor-disk emission in a tangible way. We thus claim that the conventional treatment of spectral hardening in the disk atmosphere may be insufficient to fully account for the observed disk continuum in the presence of strong wind scattering. It is suggested that the effect of scattering process (by f w ) should be incorporated to accurately evaluate an intrinsic disk spectrum besides the conventional hardening (color correction) factor (by f c ). We argue that BH spin measurements using thermal continuum-fitting in transient XRBs may well be mildly (if not significantly) altered by such spectral "contamination."}, archive = {J_ApJ}, author = {Keigo Fukumura}, doi = {10.3847/1538-4357/adb962}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {88}, shortjournal = {The Astrophys. J.}, title = {Compton scattering of thermal disk radiation with black hole disk winds}, volume = {982}, year = {2025}, }
• (2025). Cosmological predictions for minor axis stellar density profiles in the inner regions of milky way–mass galaxies. ApJ, 982(2), 87. (www)

  @article{ , abstract = {ΛCDM cosmology predicts the hierarchical formation of galaxies, which build up mass by merger events and accreting smaller systems. The stellar halo of the Milky Way (MW) has proven to be useful a tool for tracing this accretion history. However, most of this work has focused on the outer halo where dynamical times are large and the dynamical properties of accreted systems are preserved. In this work, we investigate the inner galaxy regime, where dynamical times are relatively small and systems are generally completely phase mixed. Using the FIRE-2 and Auriga cosmological zoom-in simulation suites of MW-mass galaxies, we find the stellar density profiles along the minor axis (perpendicular to the galactic disk) within the Navarro–Frenk–White scale radii ( R ≈ 15 kpc) are best described as an exponential disk with scale height < 0.3 kpc and a power-law component with slope α ≈ −4. The stellar density amplitude and slope for the power-law component are not significantly correlated with metrics of the galaxy's accretion history. Instead, we find the stellar profiles strongly correlate with the dark matter profile. Across simulation suites, the galaxies studied in this work have a stellar-to-dark-matter mass ratio that decreases as 1/ r 2 along the minor axis.}, archive = {J_ApJ}, author = {Madeline Lucey and Robyn E. Sanderson and Danny Horta and Aritra Kundu and Philip F. Hopkins and Arpit Arora and Jasjeev Singh and Nondh Panithanpaisal}, doi = {10.3847/1538-4357/adb9e8}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {87}, shortjournal = {The Astrophys. J.}, title = {Cosmological predictions for minor axis stellar density profiles in the inner regions of milky way–mass galaxies}, volume = {982}, year = {2025}, }
• (2025). Constraints on evolutions of fundamental constants from clustering of fast radio burst dispersion measure. ApJ, 982(2), 86. (www)

  @article{ , abstract = {Constrained measurements of fundamental physical constants using astronomical observational data represent a powerful method for investigating potential new physics. In particular, the dispersion measure (DM) of fast radio bursts (FRBs), which probes the electron density along their propagation paths, may be influenced by the spacetime variation of the fine-structure constant α . In this study, we analyze the cross-correlation signal between foreground galaxies and the DM of background FRBs to constrain the evolution of α . Assuming large-scale structure galaxy surveys with the capabilities of the China Space Station Telescope at z = 0.15 and a mock FRB survey with N FRB = 10 5 at z = 0.4, we test how well α variation can be constrained, with a standard deviation of σ (Δ α / α ) = 0.0007 at z = 0.15. Furthermore, taking into account the nonminimal coupling between the scalar field and the electromagnetic field, the variation in α can lead to the nonconservation of the photon number along geodesics. This would result in a violation of the CDDR and affect the evolution of the cosmic microwave background (CMB) temperature. In this work, we obtain constraint results on the CDDR parameter η and the parameter β governing CMB temperature evolution at z = 0.15, yielding σ ( η ) = 0.0004 and σ ( β ) = 0.0006, respectively. Finally, we relate the variation in α to the time evolution of the proton-to-electron mass ratio, reporting a standard deviation of σ (Δ μ / μ ) = 0.002 at z = 0.15. Future FRB surveys hold significant potential for advancing our understanding of the evolution of fundamental physical constants.}, archive = {J_ApJ}, author = {Shi-Yuan Wang and Jun-Qing Xia}, doi = {10.3847/1538-4357/adba4a}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {86}, shortjournal = {The Astrophys. J.}, title = {Constraints on evolutions of fundamental constants from clustering of fast radio burst dispersion measure}, volume = {982}, year = {2025}, }
• (2025). A rigorous solution to the superluminal issue in the diffusion equation. ApJ, 982(2), 85. (www)

  @article{ , abstract = {Superluminal propagation is an intrinsic problem in the diffusion equation and has not been effectively addressed for a long time. In this work, a rigorous solution to this issue is obtained under the assumption that particles undergo a random flight process, where they move isotropically at a constant speed while experiencing random scatterings. We validate this solution by comparing it with comprehensive simulations of the random flight process and find that it significantly deviates from the solution derived from the Jüttner propagator. This solution is broadly applicable to various diffusion phenomena, such as cosmic-ray propagation. We emphasize that our rigorous solution is particularly crucial in scenarios involving burst-like particle injection, where previous phenomenological approaches to the superluminal diffusion problem may not yield accurate results.}, archive = {J_ApJ}, author = {Xing-Jian Lv and Xiao-Jun Bi and Kun Fang and Peng-Fei Yin and Meng-Jie Zhao}, doi = {10.3847/1538-4357/adba55}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {85}, shortjournal = {The Astrophys. J.}, title = {A rigorous solution to the superluminal issue in the diffusion equation}, volume = {982}, year = {2025}, }
• (2025). Swift observations of gaia BH3. ApJ, 982(2), 84. (www)

  @article{ , abstract = {We present UV and X-ray observations, obtained with the Swift Observatory, of Gaia BH3, a binary system containing a 33 M ⊙ black hole discovered through Gaia astrometry. The system is well detected in all UV and optical filters (1700–6500 Å). We compare our results with the modeling of the noncollapsed component using synthetic stellar libraries, and a good agreement is found with our UV observations.}, archive = {J_ApJ}, author = {Boris Sbarufatti and Renato Falomo and Aldo Treves}, doi = {10.3847/1538-4357/adbbcd}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {84}, shortjournal = {The Astrophys. J.}, title = {Swift observations of gaia BH3}, volume = {982}, year = {2025}, }
• (2025). Simulating a stellar binary merger. II. obtaining a light curve*. ApJ, 982(2), 83. (www)

  @article{ , abstract = {Luminous red novae are enigmatic transient events distinguished by a rapid rise in luminosity, a plateau in luminosity, and spectra, which become redder with time. The best-observed system before, during, and after the outburst is V1309 Sco. We model a candidate V1309 Sco progenitor binary configuration (1.52 + 0.16 M ⊙ ) using the smoothed particle hydrodynamics (SPH) code StarSmasher with a modified energy equation that implements flux-limited emission-diffusion radiative transport in a Lagrangian case. We developed an imaging technique allowing us to capture the flux an observer would measure. In this novel method, the outgoing radiative flux of each SPH particle in the observer's direction is attenuated by other particles along the path to the observer. We investigated how the light curve is affected in various models: with and without dust formation; constant, Planck, or Rosseland mean opacities; different donor star sizes; different companion star masses and types; radiative heating included in our modified energy equation; and different SPH simulation resolutions. The resulting evolution in bolometric luminosity and spectrum peak temperature is in good agreement with V1309 Sco observations. Our simulations rule out V1309 Sco models that do not assume dust formation.}, archive = {J_ApJ}, author = {Roger W. M. Hatfull and Natalia Ivanova}, doi = {10.3847/1538-4357/ada6b8}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {83}, shortjournal = {The Astrophys. J.}, title = {Simulating a stellar binary merger. II. obtaining a light curve*}, volume = {982}, year = {2025}, }
• (2025). New constraints on the evolution of the MH i−M⋆ scaling relation combining CHILES and MIGHTEE-H i data. ApJ, 982(2), 82. (www)

  @article{ , abstract = {The improved sensitivity of interferometric facilities to the 21 cm line of atomic hydrogen (H i ) enables studies of its properties in galaxies beyond the local Universe. In this work, we perform a 21 cm line spectral stacking analysis combining the MeerKAT International GigaHertz Tiered Extragalactic Exploration and COSMOS H i Large Extra-galactic Survey surveys in the COSMOS field to derive a robust H i –stellar mass relation at z ≈ 0.36. In particular, by stacking thousands of star-forming galaxies subdivided into stellar mass bins, we optimize the signal-to-noise ratio of targets and derive mean H i masses in the different stellar mass intervals for the investigated galaxy population. We combine spectra from the two surveys, estimate H i masses, and derive the scaling relation {\mathrm{log}}_{10}{M}_{{\rm{H}}{\rm\small{I}}}=(0.32\pm 0.04){\mathrm{log}}_{10}{M}_{\star }+(6.65\pm 0.36) . Our findings indicate that galaxies at z ≈ 0.36 are H i richer than those at z ≈ 0 but H i poorer than those at z ≈ 1, with a slope consistent across redshift, suggesting that stellar mass does not significantly affect H i exchange mechanisms. We also observe a slower growth rate H i relative to the molecular gas, supporting the idea that the accretion of cold gas is slower than the rate of consumption of molecular gas to form stars. This study contributes to understanding the role of atomic gas in galaxy evolution and sets the stage for future development of the field in the upcoming Square Kilometre Array era.}, archive = {J_ApJ}, author = {Alessandro Bianchetti and Francesco Sinigaglia and Giulia Rodighiero and Ed Elson and Mattia Vaccari and D.J. Pisano and Nicholas Luber and Isabella Prandoni and Kelley Hess and Maarten Baes and Elizabeth A.K. Adams and Filippo M. Maccagni and Alvio Renzini and Laura Bisigello and Min Yun and Emmanuel Momjian and Hansung B. Gim and Hengxing Pan and Thomas A. Oosterloo and Richard Dodson and Danielle Lucero and Bradley S. Frank and Olivier Ilbert and Luke J.M. Davies and Ali A. Khostovan and Mara Salvato}, doi = {10.3847/1538-4357/adb1b8}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {82}, shortjournal = {The Astrophys. J.}, title = {New constraints on the evolution of the MH i−M⋆ scaling relation combining CHILES and MIGHTEE-H i data}, volume = {982}, year = {2025}, }
• (2025). Let there be neutrons! hadronic photoproduction from a large flux of high-energy photons. ApJ, 982(2), 81. (www)

  @article{ , abstract = {We propose that neutrons may be generated in high-energy, high-flux photon environments via photo-induced reactions on pre-existing baryons. These photohadronic interactions are expected to occur in astrophysical jets and surrounding material. Historically, these reactions have been attributed to the production of high-energy cosmic rays and neutrinos. We estimate the photoproduction off of protons in the context of gamma-ray bursts, where it is expected there will be sufficient baryonic material that may be encompassing or entrained in the jet. We show that typical stellar baryonic material, even material completely devoid of neutrons, can become inundated with neutrons in situ via hadronic photoproduction. Consequently, this mechanism provides a means for collapsars and other astrophysical sites containing substantial flux of high-energy photons to be favorable for neutron-capture nucleosynthesis.}, archive = {J_ApJ}, author = {Matthew R. Mumpower and Tsung-Shung H. Lee and Nicole Lloyd-Ronning and Brandon L. Barker and Axel Gross and Samuel Cupp and Jonah M. Miller}, doi = {10.3847/1538-4357/adb1e3}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {81}, shortjournal = {The Astrophys. J.}, title = {Let there be neutrons! hadronic photoproduction from a large flux of high-energy photons}, volume = {982}, year = {2025}, }
• (2025). VERITAS and multiwavelength observations of the blazar b3 2247+381 in response to an IceCube neutrino alert. ApJ, 982(2), 80. (www)

  @article{ , abstract = {While the sources of the diffuse astrophysical neutrino flux detected by the IceCube Neutrino Observatory are still largely unknown, one of the promising methods to improve our understanding of them is investigating the potential temporal and spatial correlations between neutrino alerts and the electromagnetic radiation from blazars. We report on the multiwavelength target-of-opportunity observations of the blazar B3 2247+381, taken in response to an IceCube multiplet alert for a cluster of muon neutrino events compatible with the source location between 2022 May 20 and 2022 November 10. B3 2247+381 was not detected with VERITAS during this time period. The source was found to be in a low-flux state in the optical, ultraviolet, and gamma-ray bands for the time interval corresponding to the neutrino event, but was detected in the hard X-ray band with NuSTAR during this period. We find the multiwavelength spectral energy distribution is described well using a simple one-zone leptonic synchrotron self-Compton radiation model. Moreover, assuming the neutrinos originate from hadronic processes within the jet, the neutrino flux would be accompanied by a photon flux from the cascade emission, and the integrated photon flux required in such a case would significantly exceed the total multiwavelength fluxes and the VERITAS upper limits presented here. The lack of flaring activity observed with VERITAS, combined with the low multiwavelength flux levels, as well as the significance of the neutrino excess being at a 3 σ level (uncorrected for trials), makes B3 2247+381 an unlikely source of the IceCube multiplet. We conclude that the neutrino excess is likely a background fluctuation.}, archive = {J_ApJ}, author = {A. Acharyya and C. B. Adams and P. Bangale and J. T. Bartkoske and W. Benbow and J. H. Buckley and J. L. Christiansen and A. Duerr and M. Errando and M. Escobar Godoy and A. Falcone and Q. Feng and J. Foote and L. Fortson and A. Furniss and G. Gallagher and W. Hanlon and D. Hanna and O. Hervet and C. E. Hinrichs and J. Hoang and J. Holder and T. B. Humensky and W. Jin and M. N. Johnson and P. Kaaret and M. Kertzman and M. Kherlakian and D. Kieda and T. K. Kleiner and N. Korzoun and F. Krennrich and S. Kumar and M. J. Lang and M. Lundy and C. E McGrath and E. Meyer and M. J. Millard and J. Millis and C. L. Mooney and P. Moriarty and R. Mukherjee and W. Ning and S. O’Brien and R. A. Ong and M. Pohl and E. Pueschel and J. Quinn and P. L. Rabinowitz and K. Ragan and P. T. Reynolds and D. Ribeiro and E. Roache and J. L. Ryan and I. Sadeh and A. C. Sadun and L. Saha and M. Santander and G. H. Sembroski and R. Shang and M. Splettstoesser and D. Tak and A. K. Talluri and J. V. Tucci and J. Valverde and D. A. Williams and S. L. Wong and J. Woo and (The VERITAS Collaboration) and R. Abbasi and M. Ackermann and J. Adams and S. K. Agarwalla and J. A. Aguilar and M. Ahlers and J.M. Alameddine and N. M. Amin and K. Andeen and C. Argüelles and Y. Ashida and S. Athanasiadou and S. N. Axani and R. Babu and X. Bai and A. Balagopal V. and M. Baricevic and S. W. Barwick and S. Bash and V. Basu and R. Bay and J. J. Beatty and J. Becker Tjus and J. Beise and C. Bellenghi and S. BenZvi and D. Berley and E. Bernardini and D. Z. Besson and E. Blaufuss and L. Bloom and S. Blot and F. Bontempo and J. Y. Book Motzkin and C. Boscolo Meneguolo and S. Böser and O. Botner and J. Böttcher and J. Braun and B. Brinson and Z. Brisson-Tsavoussis and J. Brostean-Kaiser and L. Brusa and R. T. Burley and D. Butterfield and M. A. Campana and I. Caracas and K. Carloni and J. Carpio and S. Chattopadhyay and N. Chau and Z. Chen and D. Chirkin and S. Choi and B. A. Clark and A. Coleman and P. Coleman and G. H. Collin and A. Connolly and J. M. Conrad and R. Corley and D. F. Cowen and C. De Clercq and J. J. DeLaunay and D. Delgado and S. Deng and A. Desai and P. Desiati and K. D. de Vries and G. de Wasseige and T. DeYoung and A. Diaz and J. C. Díaz-Vélez and P. Dierichs and M. Dittmer and A. Domi and L. Draper and H. Dujmovic and D. Durnford and K. Dutta and M. A. DuVernois and T. Ehrhardt and L. Eidenschink and A. Eimer and P. Eller and E. Ellinger and S. El Mentawi and D. Elsässer and R. Engel and H. Erpenbeck and J. Evans and P. A. Evenson and K. L. Fan and K. Fang and K. Farrag and A. R. Fazely and A. Fedynitch and N. Feigl and S. Fiedlschuster and C. Finley and L. Fischer and D. Fox and A. Franckowiak and S. Fukami and P. Fürst and J. Gallagher and E. Ganster and A. Garcia and M. Garcia and G. Garg and E. Genton and L. Gerhardt and A. Ghadimi and C. Girard-Carillo and C. Glaser and T. Glüsenkamp and J. G. Gonzalez and S. Goswami and A. Granados and D. Grant and S. J. Gray and S. Griffin and S. Griswold and K. M. Groth and D. Guevel and C. Günther and P. Gutjahr and C. Ha and C. Haack and A. Hallgren and L. Halve and F. Halzen and L. Hamacher and H. Hamdaoui and M. Ha Minh and M. Handt and K. Hanson and J. Hardin and A. A. Harnisch and P. Hatch and A. Haungs and J. Häussler and K. Helbing and J. Hellrung and J. Hermannsgabner and L. Heuermann and N. Heyer and S. Hickford and A. Hidvegi and C. Hill and G. C. Hill and R. Hmaid and K. D. Hoffman and S. Hori and K. Hoshina and M. Hostert and W. Hou and T. Huber and K. Hultqvist and M. Hünnefeld and R. Hussain and K. Hymon and A. Ishihara and W. Iwakiri and M. Jacquart and S. Jain and O. Janik and M. Jansson and M. Jeong and M. Jin and B. J. P. Jones and N. Kamp and D. Kang and W. Kang and X. Kang and A. Kappes and D. Kappesser and L. Kardum and T. Karg and M. Karl and A. Karle and A. Katil and U. Katz and M. Kauer and J. L. Kelley and M. Khanal and A. Khatee Zathul and A. Kheirandish and J. Kiryluk and S. R. Klein and Y. Kobayashi and A. Kochocki and R. Koirala and H. Kolanoski and T. Kontrimas and L. Köpke and C. Kopper and D. J. Koskinen and P. Koundal and M. Kowalski and T. Kozynets and J. Krishnamoorthi and K. Kruiswijk and E. Krupczak and A. Kumar and E. Kun and N. Kurahashi and N. Lad and C. Lagunas Gualda and M. Lamoureux and M. J. Larson and F. Lauber and J. P. Lazar and J. W. Lee and K. Leonard DeHolton and A. Leszczyńska and J. Liao and M. Lincetto and Y. T. Liu and M. Liubarska and C. Love and L. Lu and F. Lucarelli and W. Luszczak and Y. Lyu and J. Madsen and E. Magnus and K. B. M. Mahn and Y. Makino and E. Manao and S. Mancina and A. Mand and W. Marie Sainte and I. C. Mariş and S. Marka and Z. Marka and M. Marsee and I. Martinez-Soler and R. Maruyama and F. Mayhew and F. McNally and J. V. Mead and K. Meagher and S. Mechbal and A. Medina and M. Meier and Y. Merckx and L. Merten and J. Mitchell and T. Montaruli and R. W. Moore and Y. Morii and R. Morse and M. Moulai and T. Mukherjee and R. Naab and M. Nakos and U. Naumann and J. Necker and A. Negi and L. Neste and M. Neumann and H. Niederhausen and M. U. Nisa and K. Noda and A. Noell and A. Novikov and A. Obertacke Pollmann and V. O’Dell and A. Olivas and R. Orsoe and J. Osborn and E. O’Sullivan and V. Palusova and H. Pandya and N. Park and G. K. Parker and V. Parrish and E. N. Paudel and L. Paul and C. Pérez de los Heros and T. Pernice and J. Peterson and A. Pizzuto and M. Plum and A. Pontén and Y. Popovych and M. Prado Rodriguez and B. Pries and R. Procter-Murphy and G. T. Przybylski and L. Pyras and C. Raab and J. Rack-Helleis and N. Rad and M. Ravn and K. Rawlins and Z. Rechav and A. Rehman and P. Reichherzer and E. Resconi and S. Reusch and W. Rhode and B. Riedel and A. Rifaie and E. J. Roberts and S. Robertson and S. Rodan and G. Roellinghoff and M. Rongen and A. Rosted and C. Rott and T. Ruhe and L. Ruohan and D. Ryckbosch and I. Safa and J. Saffer and D. Salazar-Gallegos and P. Sampathkumar and A. Sandrock and S. Sarkar and J. Savelberg and P. Savina and P. Schaile and M. Schaufel and H. Schieler and S. Schindler and L. Schlickmann and B. Schlüter and F. Schlüter and N. Schmeisser and T. Schmidt and J. Schneider and F. G. Schröder and L. Schumacher and S. Schwirn and S. Sclafani and D. Seckel and L. Seen and M. Seikh and M. Seo and S. Seunarine and P. Sevle Myhr and R. Shah and S. Shefali and N. Shimizu and M. Silva and B. Skrzypek and B. Smithers and R. Snihur and J. Soedingrekso and A. Søgaard and D. Soldin and P. Soldin and G. Sommani and C. Spannfellner and G. M. Spiczak and C. Spiering and J. Stachurska and M. Stamatikos and T. Stanev and T. Stezelberger and T. Stürwald and T. Stuttard and G. W. Sullivan and I. Taboada and S. Ter-Antonyan and A. Terliuk and M. Thiesmeyer and W. G. Thompson and J. Thwaites and S. Tilav and K. Tollefson and C. Tönnis and S. Toscano and D. Tosi and A. Trettin and R. Turcotte and M. A. Unland Elorrieta and A. K. Upadhyay and K. Upshaw and A. Vaidyanathan and N. Valtonen-Mattila and J. Vandenbroucke and N. van Eijndhoven and D. Vannerom and J. van Santen and J. Vara and F. Varsi and J. Veitch-Michaelis and M. Venugopal and M. Vereecken and S. Vergara Carrasco and S. Verpoest and D. Veske and A. Vijai and C. Walck and A. Wang and C. Weaver and P. Weigel and A. Weindl and J. Weldert and A. Y. Wen and C. Wendt and J. Werthebach and M. Weyrauch and N. Whitehorn and C. H. Wiebusch and D. R. Williams and L. Witthaus and M. Wolf and G. Wrede and X. W. Xu and J. P. Yanez and E. Yildizci and S. Yoshida and R. Young and S. Yu and T. Yuan and A. Zegarelli and S. Zhang and Z. Zhang and P. Zhelnin and P. Zilberman and M. Zimmerman and (The IceCube Collaboration) and P. Drake and E. Spira-Savett and P. Lusen and K. Mori}, doi = {10.3847/1538-4357/adb30c}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {80}, shortjournal = {The Astrophys. J.}, title = {VERITAS and multiwavelength observations of the blazar b3 2247+381 in response to an IceCube neutrino alert}, volume = {982}, year = {2025}, }
• (2025). New cold subdwarf discoveries from backyard worlds and a metallicity classification system for t subdwarfs. ApJ, 982(2), 79. (www)

  @article{ , abstract = {We report the results of a spectroscopic survey of candidate T subdwarfs identified by the Backyard Worlds: Planet 9 program. Near-infrared spectra of 31 sources with red J − W2 colors and large J -band reduced proper motions show varying signatures of subsolar metallicity, including strong collision-induced H 2 absorption, obscured methane and water features, and weak K i absorption. These metallicity signatures are supported by spectral model fits and 3D velocities, indicating thick disk and halo population membership for several sources. We identify three new metal-poor T subdwarfs ([M/H] ≲ –0.5), CWISE J062316.19+071505.6, WISEA J152443.14−262001.8, and CWISE J211250.11-052925.2; and 19 new "mild" subdwarfs with modest metal deficiency ([M/H] ≲ −0.25). We also identify three metal-rich brown dwarfs with thick disk kinematics. We provide kinematic evidence that the extreme L subdwarf 2MASS J053253.46+824646.5 and the mild T subdwarf CWISE J113010.07+313944.7 may be part of the Thamnos population, while the T subdwarf CWISE J155349.96+693355.2 may be part of the Helmi stream. We define a metallicity classification system for T dwarfs that adds mild subdwarfs (d/sdT), subdwarfs (sdT), and extreme subdwarfs (esdT) to the existing dwarf sequence. We also define a metallicity spectral index that correlates with metallicities inferred from spectral model fits and iron abundances from stellar primaries of benchmark T dwarf companions. This expansion of the T dwarf classification system supports investigations of ancient, metal-poor brown dwarfs now being uncovered in deep imaging and spectroscopic surveys.}, archive = {J_ApJ}, author = {Adam J. Burgasser and Adam C. Schneider and Aaron M. Meisner and Dan Caselden and Chih-Chun Hsu and Roman Gerasimov and Christian Aganze and Emma Softich and Preethi Karpoor and Christopher A. Theissen and Hunter Brooks and Thomas P. Bickle and Jonathan Gagné and Ètienne Artigau and Michaël Marsset and Austin Rothermich and Jacqueline K. Faherty and J. Davy Kirkpatrick and Marc J. Kuchner and Nikolaj Stevnbak Andersen and Paul Beaulieu and Guillaume Colin and Jean Marc Gantier and Leopold Gramaize and Les Hamlet and Ken Hinckley and Martin Kabatnik and Frank Kiwy and David W. Martin and Diego H. Massat and William Pendrill and Arttu Sainio and Jörg Schümann and Melina Thévenot and Jim Walla and Zbigniew Wędracki and The Backyard Worlds: Planet 9 Collaboration}, doi = {10.3847/1538-4357/adb39f}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {79}, shortjournal = {The Astrophys. J.}, title = {New cold subdwarf discoveries from backyard worlds and a metallicity classification system for t subdwarfs}, volume = {982}, year = {2025}, }
• (2025). Ca ii k polar network index of the sun: A proxy for historical polar magnetic field. ApJ, 982(2), 78. (www)

  @article{ , abstract = {The Sun's polar magnetic field is pivotal in understanding solar dynamo processes and forecasting future solar cycles. However, direct measurements of the polar field have only been available since the 1970s. The chromospheric Ca ii K polar network index (PNI; the fractional area of the chromospheric network regions above a certain latitude) has recently emerged as a reliable proxy for polar magnetic fields. In this study, we derive PNI estimates from newly calibrated, rotation-corrected Ca ii K observations from the Kodaikanal Solar Observatory (1904–2007) and modern data from the Rome Precision Solar Photometric Telescope (2000–2022). We use both of those Ca ii K archives to identify polar network regions with an automatic adaptive threshold segmentation technique and calculate the PNI. The PNI obtained from both the archives shows a significant correlation with the measured polar field from the Wilcox Solar Observatory (Pearson correlation coefficient r > 0.93) and the derived polar field based on an Advective Flux Transport Model ( r > 0.91). The PNI series also shows a significant correlation with faculae counts derived from Mount Wilson Observatory observations ( r > 0.87) for both Kodaikanal Solar Observatory and Rome Precision Solar Photometric Telescope data. Finally, we use the PNI series from both archives to reconstruct the polar magnetic field over a 119 yr long period, which includes the last 11 solar cycles (Cycles 14–24). We also obtain a relationship between the amplitude of solar cycles (in 13 month smoothed sunspot number) and the strength of the reconstructed polar field at the preceding solar cycle minimum to validate the prediction of the ongoing solar cycle, Cycle 25.}, archive = {J_ApJ}, author = {Dibya Kirti Mishra and Bibhuti Kumar Jha and Theodosios Chatzistergos and Ilaria Ermolli and Dipankar Banerjee and Lisa A. Upton and M. Saleem Khan}, doi = {10.3847/1538-4357/adb3a8}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {78}, shortjournal = {The Astrophys. J.}, title = {Ca ii k polar network index of the sun: A proxy for historical polar magnetic field}, volume = {982}, year = {2025}, }
• (2025). The multiwavelength extinction law and its variation in the coalsack molecular cloud based on the gaia, APASS, SMSS, 2MASS, GLIMPSE, and WISE surveys. ApJ, 982(2), 77. (www)

  @article{ , abstract = {Accurate interpretation of observations relies on the interstellar dust extinction law, which also serves as a powerful diagnostic for probing dust properties. In this study, we investigate the multiwavelength extinction law of the quiescent, starless molecular cloud Coalsack and explore its potential variation across different interstellar environments: the surrounding region, the nearby high Galactic latitude region, the inner dense region, and the inner diffuse region. Using a sample of 368,524 dwarf stars selected from Gaia DR3 as tracers, we establish the effective temperature T eff –intrinsic color relations to derive the intrinsic color indices and optical−mid-infrared (MIR) color excess (CE) for 20 bands. Linear fits to the CE–CE diagrams provide CE ratios, which are subsequently converted into relative extinction. The resulting extinction curves for different environments exhibit steep slopes in the near-infrared (NIR) and flat profiles in the MIR. In the optical–NIR range, the Coalsack extinction law is consistent with the R V = 3.1 of S. Wang & X. Chen and B. S. Hensley & B. T. Draine, while in the MIR, it follows the R V = 5.5 of J. C. Weingartner & B. T. Draine, similar to the results of active star-forming clouds. At an angular resolution of 1\mathop{.}\limits^{{\rm{^{\prime} }}}3 , our extinction map reveals fine cloud structures. No correlation is found between R V and E B , V for E B , V > 0.3 mag, implying a uniform optical extinction law in the Coalsack cloud. The derived average R V value is 3.24 ± 0.32.}, archive = {J_ApJ}, author = {Juan Deng and Shu Wang and Biwei Jiang and He Zhao}, doi = {10.3847/1538-4357/adb431}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {77}, shortjournal = {The Astrophys. J.}, title = {The multiwavelength extinction law and its variation in the coalsack molecular cloud based on the gaia, APASS, SMSS, 2MASS, GLIMPSE, and WISE surveys}, volume = {982}, year = {2025}, }
• (2025). Turbulent suppression of alfvénic wave resonances in coronal loops. ApJ, 982(2), 76. (www)

  @article{ , abstract = {Alfvénic wave turbulence is a leading mechanism for explaining the heating of the solar corona and the acceleration of the solar wind. Alfvénic waves are observed to be prevalent throughout the inner corona. An intriguing aspect of the observed waves is that active-region loops show decayless standing Alfvénic oscillations, while quiet-Sun loops show only propagating Alfvénic waves. Given the weaker rates of resonant damping found in the quiet Sun (compared to those estimated from decaying oscillations of active-region loops), the reason for the lack of observed standing oscillations is unclear. We suggest that this may be due to the presence of efficient (or strong) Alfvénic wave turbulence in the quiet Sun, which limits the ability of waves to form resonant oscillations in the coronal cavity. To test this idea, we model the coronal velocity fluctuations using a previously developed 3D reduced magnetohydrodynamic model. In this model, we implement a semi-realistic profile for atmospheric plasma conditions along the magnetic field and a homogeneous plasma perpendicular to the magnetic field. Results are presented for different models of the background atmosphere that effectively have different levels of coronal turbulence. For the Alfvénic waves in the simulation, we see that resonant modes are present when the coronal turbulence is in a weak regime. However, decreasing the nonlinear timescale leads to a faster development of turbulence. This can suppress the presence of standing modes when the nonlinear timescale is comparable to or shorter than the Alfvén travel time.}, archive = {J_ApJ}, author = {Edris Tajfirouze and Richard Morton and Mahboubeh Asgari-Targhi}, doi = {10.3847/1538-4357/adb48b}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {76}, shortjournal = {The Astrophys. J.}, title = {Turbulent suppression of alfvénic wave resonances in coronal loops}, volume = {982}, year = {2025}, }
• (2025). Dynamical friction by coupled dark energy. ApJ, 982(2), 75. (www)

  @article{ , abstract = {In this paper, we examine dynamical friction at galactic scales within the framework of coupled dark energy (CDE). This model posits dark energy as coupled quintessence, which maintains a minimal coupling to gravity but interacts nonminimally with both dark matter and baryonic matter. Since our focus is primarily on the Newtonian regime within galaxies, we begin by deriving the Newtonian limit of the model. Subsequently, we calculate the dynamical friction force using three different approaches. We demonstrate that, in the absence of interaction between dark energy and matter, standard quintessence does not generate any dynamical friction at the galactic scale. However, the presence of interaction does cause dynamical friction. By applying the resulting analytic expressions to a real self-gravitating system, namely the Fornax galaxy, and by implementing the constraints on the free parameter of the model obtained from galactic observations, we demonstrate that the CDE model leads to significant deviations from the standard cold dark matter model at galactic scales. On the other hand, if the cosmological constraints are assumed for the free parameter, the effects of the model are expected to be negligible at the galactic level, at least in dynamical friction.}, archive = {J_ApJ}, author = {Nasrin Nari and Mahmood Roshan}, doi = {10.3847/1538-4357/adb621}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {75}, shortjournal = {The Astrophys. J.}, title = {Dynamical friction by coupled dark energy}, volume = {982}, year = {2025}, }
• (2025). ODIN: High clustering strength of protoclusters at cosmic noon. ApJ, 982(2), 74. (www)

  @article{ , abstract = {The One-hundred-deg 2 DECam Imaging in Narrowbands (ODIN) survey is carrying out a systematic search for protoclusters during Cosmic Noon, using Ly α -emitting galaxies (LAEs) as tracers. Once completed, ODIN aims to identify hundreds of protoclusters at redshifts of 2.4, 3.1, and 4.5 across seven extragalactic fields, covering a total area of up to 91 deg 2 . In this work, we report the high clustering strength of the ODIN protoclusters, determined via measurements of their cross-correlation with LAEs. Our sample consists of 150 protocluster candidates at z = 2.4 and 3.1, identified in two ODIN fields with a total area of 13.9 deg 2 . At z = 2.4 and 3.1, the inferred protocluster biases are 6.{6}_{-1.1}^{+1.3} and 6.{1}_{-1.1}^{+1.3} , corresponding to mean halo masses of \mathrm{log}\langle M/{M}_{\odot }\rangle =13.5{3}_{-0.24}^{+0.21} and 12.9{6}_{-0.33}^{+0.28} , respectively. By the present day, these protoclusters are expected to evolve into virialized galaxy clusters with a mean mass of ∼10 14.5 M ⊙ . By comparing the observed number density of protoclusters to that of halos with the same measured clustering strength, we find that the completeness of our sample is of order unity. Finally, the similar descendant masses derived for our samples at z = 2.4 and 3.1, assuming that the halo number density remains constant, suggest that they represent similar structures observed at different cosmic epochs. As a consequence, any observed differences between the two samples can be understood as redshift evolution. The ODIN protocluster samples will thus provide valuable insights into the cosmic evolution of cluster galaxies.}, archive = {J_ApJ}, author = {Vandana Ramakrishnan and Kyoung-Soo Lee and Nicole Firestone and Eric Gawiser and Maria Celeste Artale and Caryl Gronwall and Lucia Guaita and Ho Seong Hwang and Sang Hyeok Im and Woong-Seob Jeong and Seongjae Kim and Ankit Kumar and Jaehyun Lee and Byeongha Moon and Nelson Padilla and Changbom Park and Akriti Singh and Hyunmi Song and Paulina Troncoso Iribarren and Yujin Yang}, doi = {10.3847/1538-4357/adb624}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {74}, shortjournal = {The Astrophys. J.}, title = {ODIN: High clustering strength of protoclusters at cosmic noon}, volume = {982}, year = {2025}, }
• (2025). Probing the galactic neutrino flux at neutrino energies above 200 TeV with the baikal gigaton volume detector. ApJ, 982(2), 73. (www)

  @article{ , abstract = {Recent observations of the Galactic component of the high-energy neutrino flux, together with the detection of the diffuse Galactic gamma-ray emission up to sub-PeV energies, open new possibilities to study the acceleration and propagation of cosmic rays in the Milky Way. At the same time, both large nonastrophysical backgrounds at TeV energies and the scarcity of neutrino events in the sub-PeV band currently limit these analyses. Here, we use the sample of cascade events with estimated neutrino energies above 200 TeV, detected by the partially deployed Baikal Gigaton Volume Detector (GVD) in 6 yr of operation, to test the continuation of the Galactic neutrino spectrum to sub-PeV energies. We find that the distribution of the arrival directions of Baikal-GVD cascades above 200 TeV in the sky suggests an excess of neutrinos from low Galactic latitudes with the chance probability of 1.4 × 10 −2 . We also find the excess above 200 TeV in the most recent IceCube public data sets, both of cascades and tracks. The chance probability of the excess in the combined IceCube and Baikal-GVD analysis is 3.4 × 10 −4 . The flux of Galactic neutrinos above 200 TeV challenges often-used templates for neutrino search based on cosmic-ray simulations.}, archive = {J_ApJ}, author = {V. A. Allakhverdyan and A. D. Avrorin and A. V. Avrorin and V. M. Aynutdinov and Z. Bardačová and I. A. Belolaptikov and E. A. Bondarev and I. V. Borina and N. M. Budnev and V. A. Chadymov and A. S. Chepurnov and V. Y. Dik and G. V. Domogatsky and A. A. Doroshenko and R. Dvornický and A. N. Dyachok and Zh.-A. M. Dzhilkibaev and E. Eckerová and T. V. Elzhov and V. N. Fomin and A. R. Gafarov and K. V. Golubkov and N. S. Gorshkov and T. I. Gress and K. G. Kebkal and V. K. Kebkal and I. V. Kharuk and E. V. Khramov and M. I. Kleimenov and M. M. Kolbin and S. O. Koligaev and K. V. Konischev and A. V. Korobchenko and A. P. Koshechkin and V. A. Kozhin and M. V. Kruglov and V. F. Kulepov and A. A. Kulikov and Y. E. Lemeshev and R. R. Mirgazov and D. V. Naumov and A. S. Nikolaev and I. A. Perevalova and D. P. Petukhov and E. N. Pliskovsky and M. I. Rozanov and E. V. Ryabov and G. B. Safronov and B. A. Shaybonov and V. Y. Shishkin and E. V. Shirokov and F. Šimkovic and A. E. Sirenko and A. V. Skurikhin and A. G. Solovjev and M. N. Sorokovikov and I. Štekl and A. P. Stromakov and O. V. Suvorova and V. A. Tabolenko and V. I. Tretjak and B. B. Ulzutuev and Y. V. Yablokova and D. N. Zaborov and S. I. Zavyalov and D. Y. Zvezdov and (Baikal-GVD Collaboration) and Y. Y. Kovalev and A. V. Plavin and D. V. Semikoz and S. V. Troitsky}, doi = {10.3847/1538-4357/adb630}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {73}, shortjournal = {The Astrophys. J.}, title = {Probing the galactic neutrino flux at neutrino energies above 200 TeV with the baikal gigaton volume detector}, volume = {982}, year = {2025}, }
• (2025). Direct evidence for active galactic nuclei feedback from fast molecular outflows in reionization-era quasars. ApJ, 982(2), 72. (www)

  @article{ , abstract = {Galactic outflows driven by rapidly accreting quasars at high redshift are widely expected to play a key role in the short- and long-term future evolution of their host galaxies. Using new and archival Atacama Large Millimeter/submillimeter Array data, we observed the OH 119 μ m doublet lines in order to search for cold molecular outflows in a sample of 11 unobscured, IR-luminous quasars at z > 6. This represents the first survey for molecular winds in reionization-era quasars, and we detect unambiguous outflows in 8/11 (73%) of the quasars. The outflows we find are substantially faster, by  ≈300 km s −1 on average, than outflows observed in a roughly coeval sample of nonquasar IR-luminous galaxies, suggesting that the active galactic nuclei (AGN) drive the winds to higher velocities. On the other hand, the implied molecular outflow rates are relatively modest given the high luminosities, suggesting typical mass-loading factors ~0.5 in the cold gas. The outflows are consistent with expectations for momentum-driven winds regardless of the driving source, but the kinetic energy in the outflows suggests that the AGN must be at least partially responsible for driving the winds. Accordingly, we find trends between the outflow properties and the Eddington ratio of the black hole accretion, though this may be linked to the underlying trend with AGN luminosity. We find that the kinetic power carried in the cold outflow phase is typically only ~0.1% of the total AGN luminosity. Our study provides evidence in favor of AGN feedback on the cold molecular gas in z > 6 quasar host galaxies, demonstrating that cold outflows are very common and powerful in the most extreme reionization-era quasars.}, archive = {J_ApJ}, author = {Justin S. Spilker and Jaclyn B. Champagne and Xiaohui Fan and Seiji Fujimoto and Paul P. van der Werf and Jinyi Yang and Minghao Yue}, doi = {10.3847/1538-4357/adb750}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {72}, shortjournal = {The Astrophys. J.}, title = {Direct evidence for active galactic nuclei feedback from fast molecular outflows in reionization-era quasars}, volume = {982}, year = {2025}, }
• (2025). Revisiting the hubble constant, sound horizon, and cosmography from late-time universe observations. ApJ, 982(2), 71. (www)

  @article{ , abstract = {The Hubble tension has become one of the central problems in cosmology. In this work, we determine the Hubble constant H 0 and sound horizon r d by using the combination of baryon acoustic oscillations (BAOs) from DESI surveys, time-delay lensed quasars from H0LiCOW collaborations, and the Pantheon supernova (SN) observations. We consider two cosmological approaches, i.e., Taylor series and Padé polynomials, to avoid cosmological dependence. The reason for using this combination of data is that the absolute distance provided by strong gravitational lensing helps anchor the relative distance of BAOs, and SNe provide a robust history of Universe evolution. Combining the six time-delay distance (6 D Δ t ) plus four angular diameter distance to the deflector (4 D d ) measurements of time-delay lensed quasars, the BAOs, and the Type Ia SN data sets, we obtain a model-independent result of {r}_{d}=138.{2}_{-3.9}^{+3.3} Mpc and {H}_{0}=72.{9}_{-1.8}^{+1.8}\,\,{\rm{km}}\,{{\rm{s}}}^{-1}\,{{\rm{Mpc}}}^{-1} for the Taylor series cosmography and {r}_{d}=137.{0}_{-3.7}^{+3.2} Mpc and {H}_{0}=73.{1}_{-1.7}^{+1.8}\,\,{\rm{km}}\,{{\rm{s}}}^{-1}\,{{\rm{Mpc}}}^{-1} for the Padé polynomial cosmography. The determination of r d and H 0 prefers larger H 0 and smaller r d than Planck data under the assumption of a flat Lambda cold dark matter model. However, the values of H 0 are consistent with the H 0 determination from the SH0ES collaboration.}, archive = {J_ApJ}, author = {Zhiwei Yang and Tonghua Liu and Xiaolei Li}, doi = {10.3847/1538-4357/adb7e5}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {71}, shortjournal = {The Astrophys. J.}, title = {Revisiting the hubble constant, sound horizon, and cosmography from late-time universe observations}, volume = {982}, year = {2025}, }
• (2025). Comparison of HMG and flat rotation velocities inferred from Galaxy–Galaxy weak lensing. ApJ, 982(2), 70. (www)

  @article{ , abstract = {Despite the success of dark matter models, unresolved issues require exploring alternatives such as modified gravity theories. In this context, we examine the compatibility of the hyperconical modified gravity (HMG) with galaxy rotation curves inferred from weak-lensing data. The research addresses the existing limitations of modified Newtonian dynamics (MOND), which often struggle with universal applicability across different galactic scales. By assuming local validity of general relativity and analyzing recent data on circular velocities from galaxy–galaxy weak lensing, our findings interpret the flat rotation curves as an effect of fictitious acceleration inherited from the cosmic expansion, without invoking dark matter. The results indicate that HMG successfully reproduces flat velocity curves on scales of 1 Mpc slightly better than MOND. Therefore, these observations support HMG as a viable gravitational model, highlighting its potential to account for dynamics on galaxies and other scales. Further research with extensive data sets is required to confirm these preliminary insights.}, archive = {J_ApJ}, author = {Robert Monjo}, doi = {10.3847/1538-4357/adb8d7}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {70}, shortjournal = {The Astrophys. J.}, title = {Comparison of HMG and flat rotation velocities inferred from Galaxy–Galaxy weak lensing}, volume = {982}, year = {2025}, }
• (2025). Blowing star formation away in AGN hosts (BAH). II. investigating the origin of the h2 emission excess in nearby galaxies with JWST MIRI. ApJ, 982(2), 69. (www)

  @article{ , abstract = {We use James Webb Space Telescope Mid-Infrared Instrument Medium-resolution Spectrometer observations of 3C 293 (UGC 8782), CGCG 012-070 and NGC 3884 to investigate the origin of the H 2 emission. These three nearby active galactic nucleus (AGN) hosts are known to present H 2 emission excess relative to star-forming galaxies, as traced by the H 2 S(3)/PAH 11.3 μ m line ratio. We define the kinematically disturbed region (KDR) by the AGN and the virially dominated region based on the H 2 line widths, using the W 80 parameter. From the correlations between W 80 and H 2 S(3)/PAH11.3 μ m, as well as the higher H2 S(5)/H2 S(3) and [Fe ii ]5.34 μ m/PAH11.3 μ m ratios and flatter power-law temperature distributions observed in the KDR, we conclude that the H 2 emission in the KDR is primarily driven by shock-heated gas. For 3C 293, the KDR is cospatial with the radio core, indicating that the origin of the shocks is the interaction of the radio jet with the interstellar medium, which is also responsible for the observed molecular and ionized gas outflows in this source. The other galaxies are weak radio sources; however, due to the lack of high-resolution radio images, we cannot rule out low-power jets as the origin of the shock-heated H 2 . Our results indicate that the excess H 2 emission excess is associated with shock heating of the gas, generated by outflows or by the interaction of the radio jet with the ambient gas.}, archive = {J_ApJ}, author = {Rogemar A. Riffel and Gabriel L. Souza-Oliveira and José Henrique Costa-Souza and Nadia L. Zakamska and Thaisa Storchi-Bergmann and Rogério Riffel and Marina Bianchin}, doi = {10.3847/1538-4357/adb8dd}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {69}, shortjournal = {The Astrophys. J.}, title = {Blowing star formation away in AGN hosts (BAH). II. investigating the origin of the h2 emission excess in nearby galaxies with JWST MIRI}, volume = {982}, year = {2025}, }
• (2025). Introducing the DREAMS project: DaRk mattEr and astrophysics with machine learning and simulations. ApJ, 982(2), 68. (www)

  @article{ , abstract = {We introduce the DaRk mattEr and Astrophysics with Machine learning and Simulations (DREAMS) project, an innovative approach to understanding the astrophysical implications of alternative dark matter (DM) models and their effects on galaxy formation and evolution. The DREAMS project will ultimately comprise thousands of cosmological hydrodynamic simulations that simultaneously vary over DM physics, astrophysics, and cosmology in modeling a range of systems—from galaxy clusters to ultra-faint satellites. Such extensive simulation suites can provide adequate training sets for machine-learning-based analyses. This paper introduces two new cosmological hydrodynamical suites of warm dark matter (WDM), each comprising 1024 simulations generated using the arepo code. One suite consists of uniform-box simulations covering a {(25\,{h}^{-1}\,{\rm{Mpc}})}^{3} volume, while the other consists of Milky Way zoom-ins with sufficient resolution to capture the properties of classical satellites. For each simulation, the WDM particle mass is varied along with the initial density field and several parameters controlling the strength of baryonic feedback within the IllustrisTNG model. We provide two examples, separately utilizing emulators and convolutional neural networks, to demonstrate how such simulation suites can be used to disentangle the effects of DM and baryonic physics on galactic properties. The DREAMS project can be extended further to include different DM models, galaxy formation physics, and astrophysical targets. In this way, it will provide an unparalleled opportunity to characterize uncertainties on predictions for small-scale observables, leading to robust predictions for testing the particle physics nature of DM on these scales.}, archive = {J_ApJ}, author = {Jonah C. Rose and Paul Torrey and Francisco Villaescusa-Navarro and Mariangela Lisanti and Tri Nguyen and Sandip Roy and Kassidy E. Kollmann and Mark Vogelsberger and Francis-Yan Cyr-Racine and Mikhail V. Medvedev and Shy Genel and Daniel Anglés-Alcázar and Nitya Kallivayalil and Bonny Y. Wang and Belén Costanza and Stephanie O’Neil and Cian Roche and Soumyodipta Karmakar and Alex M. Garcia and Ryan Low and Shurui Lin and Olivia Mostow and Akaxia Cruz and Andrea Caputo and Arya Farahi and Julian B. Muñoz and Lina Necib and Romain Teyssier and Julianne J. Dalcanton and David Spergel}, doi = {10.3847/1538-4357/adb8e5}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {68}, shortjournal = {The Astrophys. J.}, title = {Introducing the DREAMS project: DaRk mattEr and astrophysics with machine learning and simulations}, volume = {982}, year = {2025}, }
• (2025). Parameter estimation with nonstationary noise in gravitational-wave data. ApJ, 982(2), 67. (www)

  @article{ , abstract = {The sensitivity of gravitational-wave (GW) detectors is characterized by their noise curves, which determine the detector's reach and ability to measure the parameters of astrophysical sources accurately. The detector noise is typically modeled as stationary and Gaussian for many practical purposes and is characterized by its power spectral density (PSD). However, due to environmental and instrumental factors, physical changes in the state of detectors may introduce nonstationarity into the noise. Misestimation of the noise behavior directly impacts the posterior width of the signal parameters. It becomes an issue for studies that depend on accurate localization volumes, such as (i) probing cosmological parameters (e.g., the Hubble constant) using cross-correlation methods with galaxies and (ii) doing electromagnetic follow-up using localization information from parameter estimation done from premerger data. We study the effects of dynamical noise on the parameter estimation of the GW events. We develop a new method to correct dynamical noise by estimating a locally valid pseudo-PSD normalized along a potential signal's time–frequency track. We do simulations by injecting binary neutron star merger signals in various scenarios where the detector goes through a period of nonstationarity with reference noise curves of third-generation detectors (Cosmic Explorer, the Einstein telescope). As an example, for a source where mismodeling of the noise biases the signal-to-noise estimate by even 10%, one would expect the estimated sky localization to be either under- or overreported by ∼20%; errors like this, especially in low latency, could potentially cause follow-up campaigns to miss the actual source location.}, archive = {J_ApJ}, author = {Sumit Kumar and Alexander H. Nitz and Xisco Jiménez Forteza}, doi = {10.3847/1538-4357/adb973}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {67}, shortjournal = {The Astrophys. J.}, title = {Parameter estimation with nonstationary noise in gravitational-wave data}, volume = {982}, year = {2025}, }
• (2025). Statistical analysis of comet disconnection events using STEREO HI and a data-assimilative solar wind model. ApJ, 982(2), 66. (www)

  @article{ , abstract = {Comets tails can reveal information about the local solar wind conditions. They can exhibit various signatures of interactions with the solar wind including bending, developing kinks, and sometimes undergoing tail disconnections. In this study, we investigate comet tail disconnection events observed in the STEREO HI data during the period of 2007–2023. Using the Heliospheric Upwind eXtrapolation model with a time-dependency (HUXt) solar wind model alongside novel solar wind data assimilation (DA) techniques, each disconnection event was investigated to determine its cause. The resulting statistical analysis led to three main conclusions: (1) for every heliospheric current sheet (HCS) crossing predicted by HUXt that occurs when the comet is within the region of influence of DA, a tail disconnection follows; (2) for HCS crossings that occur outside the region where DA can be applied, 54.5% are followed by a tail disconnection; and (3) there is an approximately linear relationship between the speed of the solar wind at the HCS crossing and the time delay to the onset of a disconnection given by the equation V rel (km s −1 ) = (2.23 ± 0.35)Δ t (hr) + (400 ± 10)(km s −1 ).}, archive = {J_ApJ}, author = {Sarah Watson and Chris Scott and Mathew Owens and Luke Barnard and Matthew Lang}, doi = {10.3847/1538-4357/adb978}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {66}, shortjournal = {The Astrophys. J.}, title = {Statistical analysis of comet disconnection events using STEREO HI and a data-assimilative solar wind model}, volume = {982}, year = {2025}, }
• (2025). Early time small-scale structures in hot exoplanet atmosphere simulations. ApJ, 982(1), 64. (www)

  @article{ , abstract = {We report on the critical influence of small-scale flow structures (e.g., fronts, vortices, and waves) that immediately arise in hot exoplanet atmosphere simulations initialized with a resting state. A hot, 1:1 spin–orbit synchronized Jupiter is used here as a clear example; but, the phenomenon is generic and important for any type of a hot synchronized planet—gaseous, oceanic, or telluric. When the early time structures are not captured in simulations (due to, e.g., poor resolution and/or too much dissipation), the flow behavior is markedly different at later times, in an observationally significant way; for example, the flow at large scales is smoother and much less dynamic. This results in the temperature field, and its corresponding thermal flux, to be incorrectly predicted in numerical simulations, even when the quantities are spatially averaged.}, archive = {J_ApJ}, author = {J. W. Skinner and J. Y-K. Cho}, doi = {10.3847/1538-4357/adb0ce}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {64}, shortjournal = {The Astrophys. J.}, title = {Early time small-scale structures in hot exoplanet atmosphere simulations}, volume = {982}, year = {2025}, }
• (2025). On the number of confirmed pulsar planets: The rule of six. ApJ, 982(1), 63. (www)

  @article{ , abstract = {Since the first definitive exoplanet detection, the three planets around millisecond radio pulsar PSR B1257+12, few more pulsar planets (PPs) have been reported. The peer-reviewed literature is ambiguous about the identity of confirmed PPs, with the number 6 appearing repeatedly, although it is generally not the same six listed pulsars or planets. We examined all claims, finding eight confirmed planets distributed among six pulsars. These objects overlap with the black widow pulsar population, there being 12 millisecond pulsars with credible companion masses below 10 Jupiter masses and little reason to choose between them. If, on the other hand, evidence for a planetary disk origin were adopted as a defining criterion, then only PSR B1257+12 with its three planets would qualify. Other claimed PP candidates have been either retracted, ruled out by subsequent studies, doubted because of mutually exclusive planetary solutions, or based on alternative theories. Long-lived quasiperiodic timing residuals are major culprits with several claimed orbital periods closely matching the data durations. Widely used exoplanet repositories differ in their inclusion criteria for PPs, resulting in large numerical discrepancies ranging from 6/8 confirmed pulsars/planets (NASA Exoplanet Archive) to 71/74 (Extrasolar Planets Encyclopaedia), which more importantly obscure a crucial distinction between planetary systems and ablated low-mass substellar companions. Tentative evidence for a spin–orbit correlation is found for the confirmed PPs, whereas such coupling is ruled out for black widows as a class. Surveys show PPs are extremely rare, yet their existence and physical properties present major challenges to understanding supernova explosions and planet formation around millisecond pulsars.}, archive = {J_ApJ}, author = {Silas G. T. Laycock and Dimitris M. Christodoulou}, doi = {10.3847/1538-4357/adb1a8}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {63}, shortjournal = {The Astrophys. J.}, title = {On the number of confirmed pulsar planets: The rule of six}, volume = {982}, year = {2025}, }
• (2025). ALMA reveals thermal and nonthermal desorption of methanol ice in the HD 100546 protoplanetary disk. ApJ, 982(1), 62. (www)

  @article{ , abstract = {Methanol (CH 3 OH) and formaldehyde (H 2 CO) are chemically coupled organic molecules proposed to act as an intermediate step between simple molecules and more complex prebiotic compounds. Their abundance distributions across disks regulate the prebiotic potential of material at different disk radii. We present observations of multiple methanol and formaldehyde transitions toward the Herbig Ae disk HD 100546 obtained with the Atacama Large Millimeter/submillimeter Array, building upon the previous serendipitous detection of methanol in this source. We find that methanol has a higher rotational temperature ( T rot ) than formaldehyde toward both the centrally concentrated emission component in the inner disk (0–110 au) and a radially separate dust ring farther out in the disk (180–260 au). T rot decreases for methanol and formaldehyde from the inner ( 15{2}_{-27}^{+35} K and 7{6}_{-8}^{+9} K) to the outer disk ( 5{2}_{-6}^{+8} K and 3{1}_{-2}^{+2} K), suggesting that we are tracing two different chemical environments. T rot for both species in the inner disk is consistent with thermal desorption as the origin, while the outer disk reservoir is driven by nonthermal desorption. The CH 3 OH/H 2 CO column density ratio decreases from {14.6}_{-4.6}^{+5.2} in the inner disk to {1.3}_{-0.2}^{+0.3} in the outer disk, consistent with modeling predictions. The CH 3 OH/H 2 CO column density ratio for the inner disk is consistent with the median value in the range of column density ratios compiled from solar system comets, which would have formed at a similar distance. This supports the notion that interstellar ice is inherited and preserved by protoplanetary disks around solar-mass and intermediate-mass stars as we are seeing "fresh" ice sublimation, as well as providing more evidence for the presence of prebiotic precursor molecules in planet-forming regions.}, archive = {J_ApJ}, author = {Lucy Evans and Alice S. Booth and Catherine Walsh and John D. Ilee and Luke Keyte and Charles J. Law and Margot Leemker and Shota Notsu and Karin Öberg and Milou Temmink and Nienke van der Marel}, doi = {10.3847/1538-4357/adb287}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {62}, shortjournal = {The Astrophys. J.}, title = {ALMA reveals thermal and nonthermal desorption of methanol ice in the HD 100546 protoplanetary disk}, volume = {982}, year = {2025}, }
• (2025). Tidal disruption of “Snow clouds” by unassociated stars. ApJ, 982(1), 61. (www)

  @article{ , abstract = {It has been suggested that star-forming galaxies may host a substantial, dark reservoir of gas in the form of planetary-mass molecular clouds that are so cold that H 2 can condense. Here we investigate the process of tidal disruption of such "snow clouds" by close passage of field stars. We construct a suite of simulations using the hydrodynamic formalism introduced by Carter and Luminet, and use it to explore the properties of the resulting tidal debris. The debris streams are tiny structures that are highly over-pressured relative to the ambient interstellar medium (ISM). They are also unusual in their composition—initially consisting of cold, gaseous He together with H 2 "snowballs" that may be as much as a meter in size. Each stream expands and cools and is subsequently shocked as it plows through the ISM; the snowballs are gradually eroded by the shocked gas. Snowballs streaming through the shocked ISM create microstructured plasma that is somewhat reminiscent of the "scattering screens" revealed by radio-wave scintillation studies. However, the tidal disruption rate is too low to account for the observed number of scattering screens if, as we assume here, the stars and clouds have no prior physical association so that disruptions occur as a result of chance encounters between stars and clouds.}, archive = {J_ApJ}, author = {Arthur G. Suvorov and Mark A. Walker}, doi = {10.3847/1538-4357/adb74b}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {61}, shortjournal = {The Astrophys. J.}, title = {Tidal disruption of “Snow clouds” by unassociated stars}, volume = {982}, year = {2025}, }
• (2025). Ejecta wakes from companion interaction in type ia supernova remnants. ApJ, 982(1), 60. (www)

  @article{ , abstract = {Type Ia supernovae are triggered by accretion onto a white dwarf from a companion that is most likely Roche lobe–filling at the time of the explosion. The collision between the ejecta and a surviving companion carves out a conical wake, which could manifest as an asymmetry when the ejecta reaches the remnant phase. We simulate the companion interaction using the Athena++ hydrodynamics solver to determine the ejecta structure for a double-degenerate type Ia supernova. Ejecta in the wake is of lower density and higher velocity than the unperturbed ejecta. We then evolve the ejecta for several thousand years using the expanding-grid code Sprout. The forward shock within the wake is initially indented, but becomes spherical after roughly a thousand years due to transverse motion of shocked ejecta that fills the wake. The reverse shock travels quickly within the wake, leading to an off-center convergence of the reverse shock and leaving the remnant with an asymmetrical core. This also draws material from the interstellar medium deep into the remnant, eventually reaching the center. Large Rayleigh–Taylor plumes are found around the edge of the wake, creating a toroidal structure composed primarily of ejecta. Estimates of the thermal X-ray emission show that such remnants exhibit observable asymmetries for thousands of years.}, archive = {J_ApJ}, author = {Logan J. Prust and Gabriel Kumar and Lars Bildsten}, doi = {10.3847/1538-4357/adb7db}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {60}, shortjournal = {The Astrophys. J.}, title = {Ejecta wakes from companion interaction in type ia supernova remnants}, volume = {982}, year = {2025}, }
• (2025). Hinode/EIS observation of the alfvénic fluctuations in the quiet sun. ApJ, 982(1), 59. (www)

  @article{ , abstract = {Alfvénic fluctuations in the corona are regularly observed in EUV imaging and infrared spectroscopic data. We report here on the Doppler velocity fluctuations within the data from the Extreme-Ultraviolet Imaging Spectrometer (EIS) on board Hinode. The capabilities of EIS provide an opportunity to detect fluctuations in the solar atmosphere and confirm the previous results from ground-based spectroscopic data using EIS's EUV spectra and in seeing-free conditions. We analyzed Doppler velocity time series for a particular date of observation, 2007 September 27, above the limb. The Fourier transform of the observed signals show the Doppler velocity has a broad spectrum distributed as a power law with a power enhancement around 3–4 mHz. This result is consistent with previous observational results obtained with Coronal Multi-Channel Polarimeter data, and hence we interpret the Doppler velocity fluctuations as Alfvénic in nature. We performed nonlinear regression on the power spectra to determine the index of the power law and to parameterize the properties of the enhancement. We find good agreement between the estimated values and those from previous studies. Furthermore, correlation analysis shows that the observed oscillations are spatially coherent perpendicular to the magnetic field on the length scale L ⊥ ∼ 8 Mm, providing an estimate on the energy injection scale of a bundle of coherently oscillating loops.}, archive = {J_ApJ}, author = {Edris Tajfirouze and Richard Morton and Peter R. Young}, doi = {10.3847/1538-4357/adb9e5}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {59}, shortjournal = {The Astrophys. J.}, title = {Hinode/EIS observation of the alfvénic fluctuations in the quiet sun}, volume = {982}, year = {2025}, }
• (2025). A simplified theory of external occulters for solar coronagraphs. ApJ, 982(1), 58. (www)

  @article{ , abstract = {We present a first-principles analytic treatment of modern multivane occulters in circular (coronagraph) and linear (heliospheric imager) geometry, develop a simplified theory that is useful for designing and predicting their performance, explain certain visual artifacts, and explore the performance limits of multivane occulters. Multivane occulters are challenging to design in part because they violate the conditions for both the Fraunhofer and Fresnel approximations to diffraction theory, and new designs have therefore generally required explicit simulation, empirical measurement, "guesstimation," or all three. Starting from the Kirchoff diffraction integral, we develop a "successive plane-wave" approximate analytic theory that is suitable for predicting the performance of multivane occulters, and use it to derive closed-form expressions for the performance of new designs. We review the fundamental 2D system of an occulter edge, discuss how it applies to real 3D systems by extrusion or revolution, present the reason for observed bright quasi-achromatic fringing around coronagraph occulters, develop the successive plane wave approximation in 2D and explore its limits, describe the relevance of the 2D theory to practical 3D instruments, and discuss implications for multivane occulter design in current and future instruments.}, archive = {J_ApJ}, author = {Craig. E. DeForest and Nicholas F. Erickson and Matthew N. Beasley and Steven N. Osterman and Travis J. Smith and Mary H. Hanson}, doi = {10.3847/1538-4357/ada270}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {58}, shortjournal = {The Astrophys. J.}, title = {A simplified theory of external occulters for solar coronagraphs}, volume = {982}, year = {2025}, }
• (2025). Effect of viewing angle in gamma-ray burst properties. ApJ, 982(1), 57. (www)

  @article{ , abstract = {The empirical classification of gamma-ray bursts (GRBs) is based on their distribution in the plane of burst duration and spectral hardness. Two distinct distributions, long-soft and short-hard bursts, are observed in this plane, forming the basis for the long and short classification scheme. Traditionally, this scheme was mapped to two different GRB progenitor classes. However, several recent bursts have challenged this mapping. This work investigates how an observer's viewing angle relative to the jet axis influences the duration-hardness plane. We simulate single-pulse GRBs using an optically and geometrically thin homogeneous top-hat jet model. Bursts are simulated with an isotropic viewing angle distribution, and we calculate the pulse duration and spectral hardness corresponding to FERMI GBM energy bands. The viewing angle significantly impacts spectral hardness for our assumed broken power-law spectra, while its effect on duration is less pronounced. Our analysis indicates that soft and low-luminous bursts are likely off-axis events. It is possible that some of the fast X-ray transients and X-ray-rich GRBs observed by the Einstein Probe and the Space Variable Objects Monitor missions originate from off-axis jets.}, archive = {J_ApJ}, author = {Sreelakshmi P. Chakyar and Sarath Prabhavu J and Lekshmi Resmi}, doi = {10.3847/1538-4357/adb1e0}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {57}, shortjournal = {The Astrophys. J.}, title = {Effect of viewing angle in gamma-ray burst properties}, volume = {982}, year = {2025}, }
• (2025). Laboratory measurements of n >= 3 K-shell transition energies of sulfur ions from F-like s viii to li-like s xiv. ApJ, 982(1), 56. (www)

  @article{ , abstract = {Inner-shell transitions are ubiquitous in nonequilibrium collisionally ionized plasmas, such as supernova remnants, and in photoionized plasmas, such as outflows from active galactic nuclei and X-ray binaries. Inner-shell X-ray emission can help determine key parameters of these systems, such as ionization time, τ , and ionization parameter, ξ . Despite their importance, only theoretical inner-shell transition energies are available for many ions. To provide experimental benchmarks, we have measured the dominant n → 1 K-shell transitions of sulfur ions where n ≥ 3 from Li-like S xiv to F-like S viii using LLNL's SuperEBIT electron beam ion trap and the NASA/GSFC EBIT Calorimeter Spectrometer (ECS). We identify over 30 spectral features and measure their energies with uncertainties in the ∼0.1–1 eV range. We compare these results to Flexible Atomic Code (FAC) and multireference Møller–Plesset (MR-MP) calculations and find differences between theory and experiment of ∼1 eV for FAC and <0.5 eV for most MR-MP calculations. We also compare these results to two widely used atomic databases, AtomDB and CHIANTI, and find discrepancies as high as 7 eV. Furthermore, many transitions are missing from these databases despite being prominent in our data.}, archive = {J_ApJ}, author = {Roi Rahin and Natalie Hell and Peter Beiersdorfer and Gregory V. Brown and Renata S. Cumbee and Richard L. Kelley and Caroline A. Kilbourne and Maurice A. Leutenegger and F. Scott Porter and Joern Wilms}, doi = {10.3847/1538-4357/adb395}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {56}, shortjournal = {The Astrophys. J.}, title = {Laboratory measurements of n >= 3 K-shell transition energies of sulfur ions from F-like s viii to li-like s xiv}, volume = {982}, year = {2025}, }
• (2025). Deep neural emulation of the supermassive black hole binary population. ApJ, 982(1), 55. (www)

  @article{ , abstract = {While supermassive black hole (SMBH) binaries are not the only viable source for the low-frequency gravitational wave background (GWB) signal evidenced by the most recent pulsar timing array (PTA) data sets, they are expected to be the most likely. Thus, connecting the measured PTA GWB spectrum and the underlying physics governing the demographics and dynamics of SMBH binaries is extremely important. Previously, Gaussian processes (GPs) and dense neural networks have been used to make such a connection by being built as conditional emulators; their input is some selected evolution or environmental SMBH binary parameters and their output is the emulated mean and standard deviation of the GWB strain ensemble distribution over many Universes. In this paper, we use a normalizing flow (NF) emulator that is trained on the entirety of the GWB strain ensemble distribution, rather than only mean and standard deviation. As a result, we can predict strain distributions that mirror underlying simulations very closely while also capturing frequency covariances in the strain distributions as well as statistical complexities such as tails, non-Gaussianities, and multimodalities that are otherwise not learnable by existing techniques. In particular, we feature various comparisons between the NF-based emulator and the GP approach used extensively in past efforts. Our analyses conclude that the NF-based emulator not only outperforms GPs in the ease and computational cost of training but also outperforms in the fidelity of the emulated GWB strain ensemble distributions.}, archive = {J_ApJ}, author = {Nima Laal and Stephen R. Taylor and Luke Zoltan Kelley and Joseph Simon and Kayhan Gültekin and David Wright and Bence Bécsy and J. Andrew Casey-Clyde and Siyuan Chen and Alexander Cingoranelli and Daniel J. D’Orazio and Emiko C. Gardiner and William G. Lamb and Cayenne Matt and Magdalena S. Siwek and Jeremy M. Wachter}, doi = {10.3847/1538-4357/adb4ef}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {55}, shortjournal = {The Astrophys. J.}, title = {Deep neural emulation of the supermassive black hole binary population}, volume = {982}, year = {2025}, }
• (2025). Gas accretion traced by blue-dominated lyα emission and redshifted UV absorption lines in protocluster galaxies at z = 2.3 from the KBSS-KCWI survey*†. ApJ, 982(1), 54. (www)

  @article{ , abstract = {Ly α emission with a dominant blueshifted peak can probe gas flowing through the circumgalactic medium as it accretes onto galaxies and fuels new star formation, although it has seldom actually been observed. Here we present new Keck Cosmic Web Imager observations of the extended Ly α halos surrounding Q1700-BX710 and Q1700-BX711, a pair of UV continuum-selected Keck Baryonic Structure Survey galaxies at z = 2.3 in the HS1700+643 protocluster. We find that BX710's and BX711's Ly α halos are aligned with a large-scale galaxy filament consisting of 13 spectroscopically identified protocluster galaxies. By measuring the peak separation and blue-to-red peak flux ratio of the Ly α emission profiles throughout these galaxies' Ly α halos, we have obtained measurements of their spatially varying velocity structure. The prevalence of blue-dominated Ly α emission profiles throughout BX711's Ly α halo suggests actively accreting gas. We fit a clumpy, multiphase Monte Carlo Radiative Transfer model, which assumes a radially varying clump velocity to the spatially resolved Ly α emission throughout BX710's and BX711's Ly α halos and simultaneously fit these galaxies' average down-the-barrel UV absorption profile with a radially varying velocity model. The results of these models are consistent with a combination of H i and higher-metallicity gas accretion for both galaxies, especially BX711, which exhibits inflow-driven kinematics throughout most of its Ly α halo. We consider various accretion scenarios to explain these findings, including accretion of metal-enriched gas from the cosmic web, galaxy interactions, and recycled gas from the circumgalactic medium, all of which are compatible with our current observations.}, archive = {J_ApJ}, author = {Claire Bolda and Zhihui Li and Dawn K. Erb and Charles C. Steidel and Yuguang Chen}, doi = {10.3847/1538-4357/adb586}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {54}, shortjournal = {The Astrophys. J.}, title = {Gas accretion traced by blue-dominated lyα emission and redshifted UV absorption lines in protocluster galaxies at z = 2.3 from the KBSS-KCWI survey*†}, volume = {982}, year = {2025}, }
• (2025). Challenges in forming millisecond Pulsar–Black holes from isolated binaries. ApJ, 982(1), 53. (www)

  @article{ , abstract = {Binaries harboring a millisecond pulsar (MSP) and a black hole (BH) are a key observing target for current and upcoming pulsar surveys. We model the formation and evolution of such binaries in isolation at solar metallicity using the next-generation binary population synthesis code POSYDON . We examine neutron star (NS)–BH binaries where the NS forms first (labeled NSBH), as the NS must be able to spin up to MSP rotation periods before the BH forms in these systems. We find that NSBHs are very rare and have a birth rate <1 Myr −1 for a Milky Way–like galaxy in our typical models. The NSBH formation rate is 2–3 orders of magnitude smaller than that for NS–BH binaries where the BH forms first (labeled BHNS). These rates are also sensitive to model assumptions about the supernova (SN) remnant masses, natal kicks, metallicity, and common-envelope (CE) evolution parameters. We find that 100% of NSBHs undergo a mass ratio reversal before the first SN and up to 52% of NSBHs undergo a double CE phase after the mass ratio reversal occurs. Most importantly, no NSBH binaries in our populations undergo a mass transfer phase, either stable or unstable, after the first SN. This implies that there is no possibility of pulsar spin-up via accretion, and thus MSP–BH binaries cannot form. Thus, dynamical environments and processes may provide the only formation channels for such MSP–BH binaries.}, archive = {J_ApJ}, author = {Camille Liotine and Vicky Kalogera and Jeff J. Andrews and Simone S. Bavera and Max Briel and Tassos Fragos and Seth Gossage and Konstantinos Kovlakas and Matthias U. Kruckow and Kyle A. Rocha and Philipp M. Srivastava and Meng Sun and Elizabeth Teng and Zepei Xing and Emmanouil Zapartas}, doi = {10.3847/1538-4357/adb84a}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {53}, shortjournal = {The Astrophys. J.}, title = {Challenges in forming millisecond Pulsar–Black holes from isolated binaries}, volume = {982}, year = {2025}, }
• (2025). Measurement of energy reduction of inertial alfvén waves propagating through parallel gradients in the alfvén speed. ApJ, 982(1), 52. (www)

  @article{ , abstract = {We have studied the propagation of inertial Alfvén waves through parallel gradients in the Alfvén speed using the Large Plasma Device at the University of California, Los Angeles. The reflection and transmission of Alfvén waves through inhomogeneities in the background plasma are important for understanding wave propagation, turbulence, and heating in space, laboratory, and astrophysical plasmas. Here we present inertial Alfvén waves under conditions relevant to solar flares and the solar corona. We find that the transmission of the inertial Alfvén waves is reduced as the sharpness of the gradient is increased. Any reflected waves were below the detection limit of our experiment, and reflection cannot account for all of the energy not transmitted through the gradient. Our findings indicate that, for both kinetic and inertial Alfvén waves, the controlling parameter for the transmission of the waves through an Alfvén speed gradient is the ratio of the Alfvén wavelength along the gradient divided by the scale length of the gradient. Furthermore, our results suggest that an as-yet-unidentified damping process occurs in the gradient.}, archive = {J_ApJ}, author = {Garima Joshi and Sayak Bose and Troy Carter and Daniel Wolf Savin and Shreekrishna Tripathi and Stephen Vincena and Michael Hahn}, doi = {10.3847/1538-4357/adb8e2}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {52}, shortjournal = {The Astrophys. J.}, title = {Measurement of energy reduction of inertial alfvén waves propagating through parallel gradients in the alfvén speed}, volume = {982}, year = {2025}, }
• (2025). The UNCOVER survey: First release of ultradeep JWST/NIRSpec PRISM spectra for ∼700 galaxies from z ∼ 0.3–13 in a2744. ApJ, 982(1), 51. (www)

  @article{ , abstract = {We present the design and observations of low-resolution JWST/NIRSpec PRISM spectroscopy from the Ultradeep NIRSpec and NIRCam ObserVations before the Epoch of Reionization (UNCOVER) Cycle 1 JWST Treasury program. Targets are selected using JWST/NIRCam photometry from UNCOVER and other programs, and cover a wide range of categories and redshifts to ensure the legacy value of the survey. These categories include the first galaxies at z ≳ 10, faint galaxies during the Epoch of Reionization ( z ∼ 6−8), high-redshift active galactic nuclei ( z ≳ 6), Population III star candidates, distant quiescent and dusty galaxies (1 ≲ z ≲ 6), and filler galaxies sampling redshift–color–magnitude space from z ∼ 0.1−13. Seven NIRSpec microshutter array masks across the extended A2744 cluster were observed, along with NIRCam parallel imaging in nine filters (F090W, F115W, F150W, F200W, F277W, F356W, F410M, F444W, and F480M) over a total area of ∼26 arcmin 2 , overlapping existing Hubble Space Telescope coverage from programs including the Hubble Frontier Fields and BUFFALO. We successfully observed 553 objects down to m F444W ∼ 30 AB, and by leveraging mask overlaps, we reach total on-target exposure times ranging from 2.4 to 16.7 hr. We demonstrate the success rate and distribution of the confirmed redshifts, and also highlight the rich information revealed by these ultradeep spectra for a subset of our targets. An updated lens model of A2744 is also presented, including 14 additional spectroscopic redshifts and finding a total cluster mass of M SL = (2.1 ± 0.3) × 10 15 M ⊙ . We publicly release reduced 1D and 2D spectra for all objects observed in summer 2023 along with a spectroscopic redshift catalog and the updated lens model of the cluster ( https://jwst-uncover.github.io/DR4.html ).}, archive = {J_ApJ}, author = {Sedona H. Price and Rachel Bezanson and Ivo Labbe and Lukas J. Furtak and Anna de Graaff and Jenny E. Greene and Vasily Kokorev and David J. Setton and Katherine A. Suess and Gabriel Brammer and Sam E. Cutler and Joel Leja and Richard Pan and Bingjie Wang and John R. Weaver and Katherine E. Whitaker and Hakim Atek and Adam J. Burgasser and Iryna Chemerynska and Pratika Dayal and Robert Feldmann and Natascha M. Förster Schreiber and Yoshinobu Fudamoto and Seiji Fujimoto and Karl Glazebrook and Andy D. Goulding and Gourav Khullar and Mariska Kriek and Danilo Marchesini and Michael V. Maseda and Tim B. Miller and Adam Muzzin and Themiya Nanayakkara and Erica Nelson and Pascal A. Oesch and Heath Shipley and Renske Smit and Edward N. Taylor and Pieter van Dokkum and Christina C. Williams and Adi Zitrin}, doi = {10.3847/1538-4357/adaec1}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {51}, shortjournal = {The Astrophys. J.}, title = {The UNCOVER survey: First release of ultradeep JWST/NIRSpec PRISM spectra for ∼700 galaxies from z ∼ 0.3–13 in a2744}, volume = {982}, year = {2025}, }
• (2025). Empirical SED templates for star clusters observed with HST and JWST: No strong PAH or IR dust emission after 5 myr. ApJ, 982(1), 50. (www)

  @article{ , abstract = {JWST observations, when combined with Hubble Space Telescope (HST) data, promise to improve age estimates of star clusters in nearby spiral galaxies. However, feedback from young cluster stars pushes out the natal gas and dust, making cluster formation and evolution a challenge to model. Here, we use JWST+ HST observations of the nearby spiral galaxy NGC 628 to produce spectral energy distribution (SED) templates of compact star clusters spanning 275 nm through 21 μ m. These preliminary SEDs capture the cluster stars and associated gas and dust within radii of ≈0 \mathop{.}\limits^\unicode{x02033} 12–0 \mathop{.}\limits^\unicode{x02033} 67 (corresponding to ≈6–33 pc at the distance of NGC 628). One important finding is that the SEDs of 1, 2, 3, and 4 Myr clusters can be differentiated in the infrared. Another is that, in 80%–90% of the cases we study, the polycyclic aromatic hydrocarbon (PAH) and H α emission track one another, with the dust responsible for the 3.3 μ m PAH emission largely removed by 4 Myr, consistent with pre-supernova stellar feedback acting quickly on the surrounding gas and dust. Nearly embedded cluster candidates have infrared SEDs that are quite similar to optically visible 1–3 Myr clusters. In nearly all cases, we find there is a young star cluster within a few tenths of an arcsec (10–30 pc) of the nearly embedded cluster, suggesting the formation of the cluster was triggered by its presence. The resulting age estimates from the empirical templates are compatible both with dynamical estimates based on CO superbubble expansion velocities, as well as the TODDLERS models, which track spherical evolution of homogeneous gas clouds around young stellar clusters.}, archive = {J_ApJ}, author = {Bradley C. Whitmore and Rupali Chandar and Janice C. Lee and Kiana F. Henny and M. Jimena Rodríguez and Dalya Baron and F. Bigiel and Médéric Boquien and Mélanie Chevance and Ryan Chown and Daniel A. Dale and Matthew Floyd and Kathryn Grasha and Simon C. O. Glover and Oleg Gnedin and Hamid Hassani and Remy Indebetouw and Anand Utsav Kapoor and Kirsten L. Larson and Adam K. Leroy and Daniel Maschmann and Fabian Scheuermann and Jessica Sutter and Eva Schinnerer and Sumit K. Sarbadhicary and David A. Thilker and Thomas G. Williams and Aida Wofford}, doi = {10.3847/1538-4357/adb3a2}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {50}, shortjournal = {The Astrophys. J.}, title = {Empirical SED templates for star clusters observed with HST and JWST: No strong PAH or IR dust emission after 5 myr}, volume = {982}, year = {2025}, }
• (2025). Foreground removal and angular power spectrum estimation of 21 cm signal using harmonic space ILC method. ApJ, 982(1), 49. (www)

  @article{ , abstract = {Mapping the distribution of neutral atomic hydrogen (H i ) in the Universe through its 21 cm emission line provides a powerful cosmological probe to map the large-scale structures and shed light on various cosmological phenomena. The baryon acoustic oscillations at low redshifts can potentially be probed by sensitive H i intensity mapping experiments and constrain the properties of dark energy. However, the 21 cm signal detection faces formidable challenges owing to the dominance of various astrophysical foregrounds, which can be several orders of magnitude stronger. Our current work introduces a novel and model-independent internal linear combination (ILC) method in harmonic space using the principal components of the 21 cm signal for accurate foreground removal and power spectrum estimation. We estimate the principal components by incorporating prior knowledge of the theoretical 21 cm covariance matrix. We test our methodology by detailed simulations of radio observations, incorporating synchrotron emission, free–free radiation, extragalactic point sources, and thermal noise. We estimate the full-sky 21 cm angular power spectrum after application of a mask on the full-sky cleaned 21 cm signal by using the mode–mode coupling matrix. These full-sky estimates of angular spectra can be directly used to measure the cosmological parameters. For the first time, we demonstrate the effectiveness of a foreground-model-independent ILC method in harmonic space to reconstruct the 21 cm signal.}, archive = {J_ApJ}, author = {Albin Joseph and Rajib Saha}, doi = {10.3847/1538-4357/adb3a9}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {49}, shortjournal = {The Astrophys. J.}, title = {Foreground removal and angular power spectrum estimation of 21 cm signal using harmonic space ILC method}, volume = {982}, year = {2025}, }
• (2025). Lyα processing of solid-state ethanolamine: Potential precursors to sugar and peptide derivatives. ApJ, 982(1), 48. (www)

  @article{ , abstract = {Ethanolamine (EA), a key component of phospholipids, has recently been detected in the interstellar medium within molecular clouds. To understand this observation, laboratory studies of its formation and destruction are essential and should be complemented by astrochemical models. This study investigates the photostability of EA ice under Ly α (10.2 eV) irradiation at 10 K, and explores its potential role in the formation of simple and complex organic molecules (COMs) in molecular clouds. The UV-destruction cross section of EA was estimated to be (4.7 ± 0.3) × 10 −18 cm 2 , providing insight into its half-life of 6.5 × 10 7 yr in dense interstellar clouds. Fourier transform infrared spectroscopy and quadrupole mass spectrometry were used to identify various photoproducts, with their formation pathways discussed. Ethylene glycol and serine were tentatively detected during the warming-up process following irradiation, suggesting that EA could contribute to the formation of prebiotic molecules such as sugars, peptides, and their derivatives. High-mass signals detected in the mass spectrometer suggest the presence of several COMs, and further analysis of residues at room temperature is planned for future work. The results suggest that EA could contribute to the formation of prebiotic molecules in space, with implications for the origin of life.}, archive = {J_ApJ}, author = {T. Suhasaria and S. M. Wee and R. Basalgète and S. Krasnokutski and C. Jäger and K. Schwarz and Th. Henning}, doi = {10.3847/1538-4357/adb486}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {48}, shortjournal = {The Astrophys. J.}, title = {Lyα processing of solid-state ethanolamine: Potential precursors to sugar and peptide derivatives}, volume = {982}, year = {2025}, }
• (2025). Investigating coronal mass ejections through multispacecraft measurements: STEREO-A and l1 in 2022–2023. ApJ, 982(1), 47. (www)

  @article{ , abstract = {The angular width of coronal mass ejections (CMEs) and the variations of CME properties for various crossings through the structure remain insufficiently studied and inadequately understood, primarily due to the rarity of multispacecraft measurements. From 2022 January to 2023 August, STEREO-A was in relative proximity to the Sun–Earth first Lagrangian (L1) point, with the STEREO-A–L1 angular separation reducing from 35 ∘ to 0 ∘ , corresponding to a time with an increasing activity of solar cycle 25 approaching its maximum. This provides a unique time period to obtain multispacecraft measurements of CMEs and to analyze their properties as observed by Wind/ACE and STEREO-A. Among 49 total CMEs measured by either spacecraft over the 20 months, only 15 were simultaneously detected at both spacecraft, indicating that only 31% of CMEs impacted both within a longitudinal separation of 0 ∘ –35 ∘ . While 80%–100% of CMEs were observed by both spacecraft within 10 ∘ , this percentage rapidly dropped to approximately 30% beyond 10 ∘ , and near 30 ∘ , it fell further to 10%. These findings suggest that the average CME angular width near 1 au is likely between 20 ∘ and 35 ∘ , smaller than previously suggested. Furthermore, the analysis of these 15 events reveals that average CME properties like magnetic field strength and proton speed are largely consistent regardless of angular separation. However, correlations and rms error analyses highlight significant variability in CME properties even within separations of 10 ∘ –20 ∘ , when examining their internal variations in detail. This study raises numerous questions about our knowledge of CME properties.}, archive = {J_ApJ}, author = {Sahanaj A. Banu and Noé Lugaz and Bin Zhuang and Nada Al-Haddad and Charles J. Farrugia and Antoinette B. Galvin}, doi = {10.3847/1538-4357/adb60c}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {47}, shortjournal = {The Astrophys. J.}, title = {Investigating coronal mass ejections through multispacecraft measurements: STEREO-A and l1 in 2022–2023}, volume = {982}, year = {2025}, }
• (2025). Rare event classification with weighted logistic regression for identifying repeating fast radio bursts. ApJ, 982(1), 46. (www)

  @article{ , abstract = {An important task in the study of fast radio bursts (FRBs) remains the automatic classification of repeating and nonrepeating sources based on their morphological properties. We propose a statistical model that considers a modified logistic regression to classify FRB sources. The classical logistic regression model is modified to accommodate the small proportion of repeaters in the data, a feature that is likely due to the sampling procedure and duration and is not a characteristic of the population of FRB sources. The weighted logistic regression hinges on the choice of a tuning parameter that represents the true proportion τ of repeating FRB sources in the entire population. The proposed method has a sound statistical foundation, direct interpretability, and operates with only five parameters, enabling quicker retraining with added data. Using the CHIME/FRB Collaboration sample of repeating and nonrepeating FRBs and numerical experiments, we achieve a classification accuracy for repeaters of nearly 75% or higher when τ is set in the range of 50%–60%. This implies a tentative high proportion of repeaters, which is surprising, but is also in agreement with recent estimates of τ that are obtained using other methods.}, archive = {J_ApJ}, author = {Antonio Herrera-Martin and Radu V. Craiu and Gwendolyn M. Eadie and David C. Stenning and Derek Bingham and B. M. Gaensler and Ziggy Pleunis and Paul Scholz and Ryan Mckinven and Bikash Kharel and Kiyoshi W. Masui}, doi = {10.3847/1538-4357/adb623}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {46}, shortjournal = {The Astrophys. J.}, title = {Rare event classification with weighted logistic regression for identifying repeating fast radio bursts}, volume = {982}, year = {2025}, }
• (2025). The role of magnetic and rotation axis alignment in driving fast radio burst phenomenology. ApJ, 982(1), 45. (www)

  @article{ , abstract = {We propose a scenario that can describe a broad range of fast radio burst (FRB) phenomenology, from nonrepeating bursts to highly prolific repeaters. Coherent radio waves in these bursts are produced in the polar cap region of a magnetar, where magnetic field lines are open. The angle between the rotation and magnetic axes, relative to the angular size of the polar cap region, partially determines the repetition rate and polarization properties of FRBs. We discuss how many of the properties of repeating FRBs—such as their lack of periodicity, energetics, small polarization angle (PA) swing, spectro–temporal correlation, and inferred low source density— are explained by this scenario. The systematic PA swing and the periodic modulation of long-duration bursts from nonrepeaters are also natural outcomes. We derive a lower limit of about 400 on the Lorentz factor of FRB sources applying this scenario to bursts with a linear polarization degree greater than 95%.}, archive = {J_ApJ}, author = {Paz Beniamini and Pawan Kumar}, doi = {10.3847/1538-4357/adb8e6}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {45}, shortjournal = {The Astrophys. J.}, title = {The role of magnetic and rotation axis alignment in driving fast radio burst phenomenology}, volume = {982}, year = {2025}, }
• (2025). 3D simulations of semiconvection in spheres: Turbulent mixing and layer formation. ApJ, 982(1), 44. (www)

  @article{ , abstract = {Semiconvection occurs in regions of stars and planets that are unstable to overturning convection according to the Schwarzschild criterion, but stable according to the Ledoux criterion. Previous simulations in Cartesian boxes have advanced our understanding of the semiconvective instability, layer formation, and transport properties. However, much less is known about semiconvection in spherical geometry and under the influence of rotation or magnetic fields. We present 3D simulations of semiconvection in the full sphere (including r = 0) and accounting for rotation. We find that the formation and evolution of semiconvective layers in nonrotating spheres occurs in a similar way to that in nonrotating Cartesian boxes, in the sense that the critical density ratio at which layers are expected to form is approximately the same in both geometries. Layers rapidly merge once they form, ultimately leading to a fully mixed convective sphere. The transport properties measured through the Nusselt numbers and the buoyancy flux ratio are also similar to results from previous studies in boxes. When rotation is added to the system, layer formation and evolution proceed in a similar fashion to the nonrotating runs. However, rotation hampers the radial transport of heat and composition, and, as a result, the time that it takes for the sphere to become fully mixed gets longer as the flow becomes more rotationally constrained. We also find that semiconvective layers exhibit spherical mixing in nonrotating cases, whereas in rotating cases the mixing becomes more cylindrical. We discuss what is needed for future work to build more realistic models.}, archive = {J_ApJ}, author = {J. R. Fuentes}, doi = {10.3847/1538-4357/adb8ec}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {44}, shortjournal = {The Astrophys. J.}, title = {3D simulations of semiconvection in spheres: Turbulent mixing and layer formation}, volume = {982}, year = {2025}, }
• (2025). The proxima centauri Campaign—First constraints on millimeter flare rates from ALMA. ApJ, 982(1), 43. (www)

  @article{ , abstract = {Proxima Centauri (Cen) has been the subject of many flaring studies due to its proximity and potential to host habitable planets. The discovery of millimeter flares from this M dwarf with Atacama Large Millimeter/submillimeter Array (ALMA) has opened a new window into the flaring process and the space-weather environments of exoplanets like Proxima b. Using a total of ~50 hr of ALMA observations of Proxima Cen at 1.3 mm (233 GHz), we add a new piece to the stellar flaring picture and report the first cumulative flare frequency distribution (FFD) at millimeter wavelengths of any M dwarf. We detect 463 flares ranging from energies 10 24 to 10 27 erg. The brightest and most energetic flare in our sample reached a flux density of 119 ± 7 mJy, increasing by a factor of 1000 × the quiescent flux, and reaching an energy of 10 27 erg in the ALMA bandpass, with t 1/2 ≈ 16 s. From a log–log linear regression fit to the FFD, we obtain a power-law index of α FFD = 2.92 ± 0.02, much steeper than α FFD values (~2) observed at X-ray to optical wavelengths. If millimeter flare rates are predictive of flare rates at extreme-UV wavelengths, the contribution of small flares to the radiation environment of Proxima b may be much higher than expected based on the shallower power-law slopes observed at optical wavelengths.}, archive = {J_ApJ}, author = {Kiana Burton and Meredith A. MacGregor and Rachel A. Osten and Ward S. Howard and Alycia J. Weinberger and Evgenya Shkolnik and David J. Wilner and Jan Forbrich and Thomas Barclay}, doi = {10.3847/1538-4357/ada5f2}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {43}, shortjournal = {The Astrophys. J.}, title = {The proxima centauri Campaign—First constraints on millimeter flare rates from ALMA}, volume = {982}, year = {2025}, }
• (2025). The long-lived broadband afterglow of short gamma-ray burst 231117A and the growing radio-detected short gamma-ray burst population. ApJ, 982(1), 42. (www)

  @article{ , abstract = {We present multiwavelength observations of the Swift short γ -ray burst GRB 231117A, localized to an underlying galaxy at redshift z = 0.257 at a small projected offset (∼2 kpc). We uncover long-lived X-ray Chandra X-ray Observatory and radio/millimeter (VLA, MeerKAT, and ALMA) afterglow emission, detected to ∼37 days and ∼20 days (rest frame), respectively. We measure a wide jet (∼10 \mathop{.}\limits^{\unicode{x000b0}} 4) and relatively high circumburst density (∼0.07 cm −3 ) compared to the short GRB population. Our data cannot be easily fit with a standard forward shock model, but they are generally well fit with the incorporation of a refreshed forward shock and a reverse shock at <1 day. We incorporate GRB 231117A into a larger sample of 132 X-ray detected events, 71 of which were radio-observed (17 cm-band detections), for a systematic study of the distributions of redshifts, jet and afterglow properties, galactocentric offsets, and local environments of events with and without detected radio afterglows. Compared to the entire short GRB population, the majority of radio-detected GRBs are at relatively low redshifts ( z < 0.6) and have high circumburst densities (>10 −2 cm −3 ), consistent with their smaller (<8 kpc) projected galactocentric offsets. We additionally find that 70% of short GRBs with opening angle measurements were radio-detected, indicating the importance of radio afterglows in jet measurements, especially in the cases of wide (>10°) jets where observational evidence of collimation may only be detectable at radio wavelengths. Owing to improved observing strategies and the emergence of sensitive radio facilities, the number of radio-detected short GRBs has quadrupled in the past decade.}, archive = {J_ApJ}, author = {Genevieve Schroeder and Wen-fai Fong and Charles D. Kilpatrick and Alicia Rouco Escorial and Tanmoy Laskar and Anya E. Nugent and Jillian Rastinejad and Kate D. Alexander and Edo Berger and Thomas G. Brink and Ryan Chornock and Clecio R. de Bom and Yuxin Dong and Tarraneh Eftekhari and Alexei V. Filippenko and Celeste Fuentes-Carvajal and Wynn V. Jacobson-Galán and Matthew Malkan and Raffaella Margutti and Jeniveve Pearson and Lauren Rhodes and Ricardo Salinas and David J. Sand and Luidhy Santana-Silva and Andre Santos and Huei Sears and Manisha Shrestha and Nathan Smith and Wayne Webb and Simon de Wet and Yi Yang}, doi = {10.3847/1538-4357/ada9e5}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {42}, shortjournal = {The Astrophys. J.}, title = {The long-lived broadband afterglow of short gamma-ray burst 231117A and the growing radio-detected short gamma-ray burst population}, volume = {982}, year = {2025}, }
• (2025). An X-ray view of the cataclysmic variable v902 mon: Discovery of an X-ray eclipse. ApJ, 982(1), 41. (www)

  @article{ , abstract = {V902 Mon is one of a few eclipsing intermediate polars (IPs) and shows deep eclipses in the optical lightcurves. The presence of a strong Fe K α fluorescence line in its X-ray spectrum and its low X-ray flux compared to other IPs suggests significant absorption, most likely from an accretion disk. In an observation carried out using the Nuclear Spectroscopic Telescope Array (NuSTAR), we confirm the presence of an X-ray eclipse in the energy-resolved lightcurves, coincident with the optical AAVSO/CV-band lightcurves. Broadband X-ray spectral analysis using NuSTAR and XMM-Newton observations confirm a strong absorption N H ∼ 10 23 cm −2 local to the source, along with a high equivalent width of about 0.7 keV for an Fe K α fluorescence line. We interpret this using a model similar to an accretion disk corona source, which has a very high inclination, and the compact object is heavily obscured by the body of the accretion disk. We propose that the primary X-rays from the accretion column in V902 Mon are hidden from our direct view at all times by the accretion disk. In this scenario, the observed scattered X-rays indicate substantial absorption of direct X-rays by the accretion disk. Additionally, a strong Fe fluorescence line suggests reprocessing of the radiation by a more extended region, such as the pre-shock region, which could be located a few white dwarf radii above the orbital plane.}, archive = {J_ApJ}, author = {Nazma Islam and Koji Mukai}, doi = {10.3847/1538-4357/adb4f1}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {41}, shortjournal = {The Astrophys. J.}, title = {An X-ray view of the cataclysmic variable v902 mon: Discovery of an X-ray eclipse}, volume = {982}, year = {2025}, }
• (2025). Planetary formation constrained by collisions between millimeter-sized lunar particles and lunar surface from Chang’E-4 mission. ApJ, 982(1), 40. (www)

  @article{ , abstract = {Exploring low-velocity collisions is crucial for unraveling intricate processes in planetary formation, particularly the bouncing barrier that impedes the aggregation of dust into sizable planetesimals. Observational data on extraterrestrial collision processes remain limited. Here, we quantify collision parameters for millimeter-sized lunar particles impacting the porous lunar surface at speeds ranging from 2.3 to 76.8 cm s −1 under lunar gravity, leveraging Chang'E-4 imagery. This study represents the first tangible acquisition of extraterrestrial collision data. Our findings reveal that speeds exceeding 7.0 ± 2.6 cm s −1 result in bouncing, yielding coefficients of restitution ranging from 0.51 to 0.80. In contrast to particle–particle collisions, interactions between lunar particles and the porous lunar surface exhibit a heightened sticking threshold speed, facilitating particles to overcome the bouncing barrier. Diminished coefficients of restitution expedite collapses, significantly reducing dust cloud collapse times. This implies that porous particles foster favorable conditions for overcoming the bouncing barrier and promoting growth. Our results unveil the conducive conditions enabling extraterrestrial samples to overcome the bouncing barrier, advancing our comprehension of planetary formation and providing crucial observational constraints for relevant theories.}, archive = {J_ApJ}, author = {Lei Lei and Xiaoping Zhang and Pengwei Luo and Guozheng Zhang and Jilin You and Jiahui Liu and Yanyan Xu and Shuai Fu and Xiongyao Li and Zhiguo Meng and Cunhui Li and Haiyan Zhang and Yunzhao Wu}, doi = {10.3847/1538-4357/adb4f5}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {40}, shortjournal = {The Astrophys. J.}, title = {Planetary formation constrained by collisions between millimeter-sized lunar particles and lunar surface from Chang’E-4 mission}, volume = {982}, year = {2025}, }
• (2025). Beyond the goldilocks zone: Identifying critical features in massive black hole formation. ApJ, 982(1), 39. (www)

  @article{ , abstract = {Most galaxies, including the Milky Way, host a supermassive black hole (SMBH) at the center. These SMBHs can be observed out to high redshifts ( z ≥ 6) if the accretion rate is sufficiently large. However, we do not fully understand the mechanism through which these black holes form at early times. The heavy (or direct collapse) seeding mechanism has emerged as a probable contender in which the core of an atomic cooling halo directly collapses into a dense stellar cluster that could host supermassive stars that proceed to form a black hole seed of mass ∼ 10 5 M ⊙ . We use the Renaissance Simulations to investigate the properties of 35 direct collapse black hole (DCBH) candidate host halos at z = 15–24 and compare them to noncandidate halos. We aim to understand what features differentiate halos capable of hosting a DCBH from the general halo population with the use of statistical analysis and machine learning methods. We examine 18 halo, central, and environmental properties. We find that DCBH candidacy is more dependent on a halo's core internal properties than on exterior factors such as Lyman–Werner (LW) flux and distance to the closest galaxy; our analysis selects density and radial mass influx as the most important features (outside candidacy establishing features). Our results concur with the recent suggestion that DCBH host halos neither need to lie within a "Goldilocks zone" nor have a significant amount of LW flux to suppress cooling. This paper presents insight to the dynamics possibly occurring in potential DCBH host halos and seeks to provide guidance to DCBH subgrid formation models.}, archive = {J_ApJ}, author = {Elizabeth Mone and Brandon Pries and John H. Wise and Sandrine Ferrans}, doi = {10.3847/1538-4357/adb4f7}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {39}, shortjournal = {The Astrophys. J.}, title = {Beyond the goldilocks zone: Identifying critical features in massive black hole formation}, volume = {982}, year = {2025}, }
• (2025). DESIVAST: Catalogs of low-redshift voids using data from the DESI data release 1 bright galaxy survey. ApJ, 982(1), 38. (www)

  @article{ , abstract = {We present three separate void catalogs created using a volume-limited sample of the DESI Data Release 1 Bright Galaxy Survey. We use the algorithms VoidFinder and V 2 to construct void catalogs out to a redshift of z = 0.24. Excluding voids affected by the boundaries of the survey, we obtain 1489 voids with VoidFinder, 389 with V 2 using REVOLVER pruning, and 297 with V 2 using VIDE pruning. Comparing our catalogs with overlapping Sloan Digital Sky Survey void catalogs, we find generally consistent void properties but significant differences in the void volume overlap, which we attribute to differences in the galaxy selection and survey masks. These catalogs are suitable for studying the variation in galaxy properties with cosmic environment and for cosmological studies.}, archive = {J_ApJ}, author = {Hernan Rincon and Segev Benzvi and Kelly Douglass and Dahlia Veyrat and Jessica Nicole Aguilar and Steven Ahlen and Davide Bianchi and David Brooks and Todd Claybaugh and Shaun Cole and Axel de la Macorra and Peter Doel and Andreu Font-Ribera and Jaime E. Forero-Romero and Enrique Gaztañaga and Satya Gontcho A Gontcho and Gaston Gutierrez and Klaus Honscheid and Cullan Howlett and Stephanie Juneau and Robert Kehoe and Sergey Koposov and Andrew Lambert and Martin Landriau and Laurent Le Guillou and Aaron Meisner and Ramon Miquel and John Moustakas and Gustavo Niz and Will Percival and Francisco Prada and Ignasi Pérez-Ràfols and Graziano Rossi and Eusebio Sanchez and Michael Schubnell and Hee-Jong Seo and David Sprayberry and Gregory Tarlé and Benjamin Alan Weaver and Hu Zou}, doi = {10.3847/1538-4357/adb559}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {38}, shortjournal = {The Astrophys. J.}, title = {DESIVAST: Catalogs of low-redshift voids using data from the DESI data release 1 bright galaxy survey}, volume = {982}, year = {2025}, }
• (2025). Dynamical models of the milky way in action space with LAMOST DR8 and gaia EDR3. ApJ, 982(1), 37. (www)

  @article{ , abstract = {This work explores dynamical models of the Milky Way (MW) by analyzing a sample of 86,109 K giant stars selected through cross-matching the LAMOST DR8 and Gaia EDR3 surveys. Our earlier torus models of Q. Wang et al. did not include Gaia data, making them incompatible with the new sample's proper motion distributions. Here, we refine the construction of action-based, self-consistent models to constrain the three-dimensional velocity distribution of K giants over a larger parameter space, drawing on a series of existing MW models. This approach produces several new MW models. Our best-fit model for the local kinematics near the Sun indicates an MW virial mass of 1.35 × 10 12 M ⊙ , a local stellar density of 0.0696 M ⊙ pc −3 , and a local dark matter density of 0.0115 M ⊙ pc −3 . Our main conclusion supports a thicker and more extended thick disk, alongside a cooler thin disk, compared to the best-fitting model of Q. Wang et al. Near the Sun, our model aligns well with observations, but it is less satisfactory at distances far from the Galactic center, perhaps implying unidentified structures. Further high-precision observations will be critical for understanding the dynamics in these outer Galactic regions and will require a more realistic model.}, archive = {J_ApJ}, author = {Guang-Chen Sun and Qiao Wang and Shude Mao and Yichao Li and Richard J. Long and Ping-Jie Ding and Yougang Wang and Xin Zhang and Xuelei Chen}, doi = {10.3847/1538-4357/adb57e}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {37}, shortjournal = {The Astrophys. J.}, title = {Dynamical models of the milky way in action space with LAMOST DR8 and gaia EDR3}, volume = {982}, year = {2025}, }
• (2025). Evidence for an accretion bridge in the DX cha circumbinary system from VLTI/MATISSE observations*. ApJ, 982(1), 36. (www)

  @article{ , abstract = {DX Cha (HD 104237) is a spectroscopic binary consisting of a Herbig A7.5Ve–A8Ve primary star and a K3-type companion. Here we report on new 3.55 μ m interferometric observations of this source with the Multi Aperture Mid-Infrared Spectroscopic Experiment (MATISSE) at the Very Large Telescope Interferometer. To model the four MATISSE observations obtained between 2020 and 2023, we constructed a time-dependent interferometric model of the system, using the oimodeler software. The model consists of an asymmetric ring and two point sources on a Keplerian orbit. Our best-fit model consists of a circumbinary ring with a diameter of 0.86 au (8.1 mas), featuring a strong azimuthal asymmetry. We found that the position angle of the asymmetry changes tens of degrees between the MATISSE epochs. The ring is relatively narrow, with a full width at half-maximum of ∼0.13 au (1.23 mas). The presence of circumstellar dust emission so close to the binary is unexpected, as previous hydrodynamic simulations predicted an inner disk cavity with a diameter of ∼4 au (∼37.5 mas). Thus, we argue that the narrow envelope of material we detected is probably not a gravitationally stable circumbinary ring but may be part of tidal accretion streamers channeling material from the inner edge of the disk toward the stars.}, archive = {J_ApJ}, author = {Tímea Juhász and József Varga and Péter Ábrahám and Ágnes Kóspál and Foteini Lykou and Lei Chen and Attila Moór and Fernando Cruz-Sáenz de Miera and Bruno Lopez and Alexis Matter and Roy van Boekel and Michiel Hogerheijde and Margaux Abello and Jean-Charles Augereau and Paul Boley and William C. Danchi and Thomas Henning and Mathis Letessier and Jie Ma and Philippe Priolet and Marten Scheuck and Gerd Weigelt and Sebastian Wolf}, doi = {10.3847/1538-4357/adb727}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {36}, shortjournal = {The Astrophys. J.}, title = {Evidence for an accretion bridge in the DX cha circumbinary system from VLTI/MATISSE observations*}, volume = {982}, year = {2025}, }
• (2025). Estimation of transit time of CMEs from the sun to earth. ApJ, 982(1), 35. (www)

  @article{ , abstract = {Coronal mass ejections (CMEs) can cause severe geomagnetic storms on Earth, making it essential to forecast their arrival. However, predicting the transit time (TT) of Earth-directed CMEs is challenging due to the complex factors involved, such as CME dynamics, the state of the interplanetary medium, and CME interactions. Our goal is to predict the TT of Earth-directed CMEs without relying on computationally expensive methods. CMEs observed from L1 are significantly affected by projection effects, which underestimate their speed and overestimate their size and mass. To address this, we use the Solar TErrestrial RElations Observatory (STEREO) to study the kinematics of halo and partial halo CMEs in quadrature and near-quadrature configurations. We analyzed a data set of 44 Earth-directed CMEs, dividing it into two categories: 25 CMEs in STEREO's quadrature field of view (FOV) and 19 CMEs in the near-quadrature FOV. Three different proxies were used to prepare empirical models for estimating TT. Our findings indicate that, for the considered sample of events, the empirical model based on the maximum speed of CMEs observed in STEREO's FOV yields the most accurate TT estimates. Our model achieved a maximum error of 16.46 hr and a mean error of 7.25 hr in estimating the TT of 44 Earth-directed CMEs.}, archive = {J_ApJ}, author = {Ashutosh Pattnaik and Grzegorz Michałek and Anitha Ravishankar}, doi = {10.3847/1538-4357/adb84b}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {35}, shortjournal = {The Astrophys. J.}, title = {Estimation of transit time of CMEs from the sun to earth}, volume = {982}, year = {2025}, }
• (2025). Cyclic c4+ as the carrier of the diffuse interstellar band at 503.9 nm?. ApJ, 982(1), 34. (www)

  @article{ , abstract = {The diffuse interstellar bands (DIBs) have remained a mystery in astronomy since their discovery over a century ago. The only currently known carrier is {{\rm{C}}}_{60}^{+} , responsible for five DIBs, while more than 550 are yet to be interpreted. The spectra of short carbon chain cations {({\rm{C}}}_{n}^{+}) , which are considered one of the most promising classes of species for the role of carriers of DIBs, are successfully recorded using He-tagging spectroscopy. The comparison of laboratory spectra with observations demonstrates a close match of two absorption bands of {{\rm{C}}}_{4}^{+} with the broad DIB at 503.9 nm. This defines a high abundance of these ions in the interstellar medium (ISM), which should exceed those of other similar-sized carbon chain cations. It is anticipated that all other short carbon chain cations will exhibit linear geometry and, as a consequence, will have a long vibrational progression. However, the distinctive cyclic geometry of {{\rm{C}}}_{4}^{+} is postulated to underpin the elevated abundance of these ions in the ISM, as well as the distinctive spectrum of this ion, which displays a single, strong, relatively narrow absorption band that exceeds in intensity all other absorption bands in the visible range.}, archive = {J_ApJ}, author = {Serge. A. Krasnokutski and Lisa Ganner and Milan Ončák and Florian Foitzik and Stefan Bergmeister and Fabio Zappa and Paul Scheier and Elisabeth Gruber}, doi = {10.3847/1538-4357/adb72e}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {34}, shortjournal = {The Astrophys. J.}, title = {Cyclic c4+ as the carrier of the diffuse interstellar band at 503.9 nm?}, volume = {982}, year = {2025}, }
• (2025). Scylla. IV. intrinsic stellar properties and line-of-sight dust extinction measurements toward 1.5 million stars in the SMC and LMC. ApJ, 982(1), 33. (www)

  @article{ , abstract = {By analyzing the spectral energy distributions (SEDs) of resolved stars in nearby galaxies, we can constrain their stellar properties and line-of-sight dust extinction. From the Scylla survey, we obtain ultraviolet to near-infrared photometry from Wide Field Camera 3 on board the Hubble Space Telescope for more than 1.5 million stars in the SMC and LMC. We use the Bayesian Extinction and Stellar Tool (BEAST) to analyze the multiband SEDs of these sources and characterize their initial masses, ages, metallicities, distances, and line-of-sight extinction properties (e.g., A V , R V ). We apply quality cuts and perform validation simulations to construct a catalog of over 550,000 stars with high-reliability SED fits, which we use to analyze the stellar content and extinction properties of the SMC and LMC. We detect stars with masses as low as 0.6 M ⊙ . BEAST stellar age distributions show a jump in observed stars around 6 Gyr ago, which agrees with star formation histories. Extinctions ( A V ) in both galaxies follow a log-normal distribution. We compare A V with ancillary gas and dust tracers like H i , H α , and far-infrared (FIR) dust emission and find positive correlations on a field-by-field basis. We convert observed A V to predicted dust surface densities using the Draine et al. model and find A V -based dust surface densities are a factor of ∼2.5 lower than observed FIR-based dust surface densities, a correction factor similar to other studies.}, archive = {J_ApJ}, author = {Christina W. Lindberg and Claire E. Murray and Petia Yanchulova Merica-Jones and Caroline Bot and Clare Burhenne and Yumi Choi and Christopher J. R. Clark and Roger E. Cohen and Karoline M. Gilbert and Steven R. Goldman and Karl D. Gordon and Alec S. Hirschauer and Kristen B. W. McQuinn and Julia C. Roman-Duval and Karin M. Sandstrom and Elizabeth Tarantino and Benjamin F. Williams}, doi = {10.3847/1538-4357/adb4e8}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {33}, shortjournal = {The Astrophys. J.}, title = {Scylla. IV. intrinsic stellar properties and line-of-sight dust extinction measurements toward 1.5 million stars in the SMC and LMC}, volume = {982}, year = {2025}, }
• (2025). A search for low-frequency radio pulses from long gamma-ray bursts with the murchison widefield array. ApJ, 982(1), 32. (www)

  @article{ , abstract = {It has been proposed that coherent radio emission could be emitted during or shortly following a gamma-ray burst (GRB). Here we present a low-frequency (170–200 MHz) search for radio pulses associated with long-duration GRBs using the Murchison Widefield Array (MWA). The MWA, with its rapid-response system, is capable of performing GRB follow-up observations within approximately 30 s. Our single pulse search, with temporal and spectral resolutions of 100 μ s and 10 kHz, covers dispersion measures up to 5000 pc cm −3 . Two single pulse candidates are identified with significance greater than 6 σ , surviving a friends-of-friends analysis. We rule out random fluctuations as their origin at a confidence level of 97% (2.2 σ ). We caution that radio frequency interference from digital TV (DTV) is most likely the origin of these pulses since the DTV frequency bands almost cover the entire observing frequency band. If they are astrophysical signals, we estimate the peak flux densities for our pulse candidates of 3.6 ± 0.6 and 10.5 ± 1.5 Jy, with corresponding fluences of 431 ± 74 and 211 ± 37 Jy ms, respectively. Based on these observations and the assumption of a magnetar origin for the pulse, we constrain the radio emission efficiency as r ∼ 10 −3 for both candidates, which is consistent with pulsar observations. Our results highlight the promising potential of new-generation radio telescopes such as the MWA to probe the central engines of GRBs.}, archive = {J_ApJ}, author = {Fan Xu and G. E. Anderson and Jun Tian and B. W. Meyers and S. J. Tingay and Yong-Feng Huang and Zi-Teng Wang and B. Venville and C. P. Lee and A. Rowlinson and P. Hancock and A. Williams and M. Sokolowski}, doi = {10.3847/1538-4357/adb71e}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {32}, shortjournal = {The Astrophys. J.}, title = {A search for low-frequency radio pulses from long gamma-ray bursts with the murchison widefield array}, volume = {982}, year = {2025}, }
• (2025). DDO 68-C: HST confirms yet another companion of the isolated dwarf galaxy DDO 68. ApJ, 982(1), 31. (www)

  @article{ , abstract = {We present the results of deep Hubble Space Telescope photometry of the dwarf galaxy DDO 68-C, proposed as possibly associated with the isolated peculiar dwarf DDO 68. The new data resolve for the first time the stars of DDO 68-C down to well below the tip of the red giant branch (RGB), revealing a low-mass ( M ⋆ ≃ 1.5 × 10 7 M ⊙ ) star-forming galaxy with a backbone of old stars. By means of a fully homogeneous analysis and using the RGB tip as a standard candle, we find that DDO 68 and DDO 68-C lie at the same distance from us, within the uncertainties ( D = 12.6 ± 0.3 Mpc and D = 12.7 ± 0.4 Mpc, respectively), thus confirming that the two dwarfs are physically associated. While paired dwarf galaxies with a mutual projected distance similar to DDO 68 and DDO 68-C are not exceptional in the Lynx-Cancer void where they live, DDO 68 remains a unicum as, in addition to the newly confirmed companion, it records the evidence of at least two other satellites.}, archive = {J_ApJ}, author = {Matteo Correnti and Francesca Annibali and Michele Bellazzini and Mariarosa Marinelli and Alessandra Aloisi and Michele Cignoni and Monica Tosi and Raffaele Pascale and John M. Cannon and Lila Schisgal and Leslie K. Hunt and Elena Sacchi and Sangmo Tony Sohn}, doi = {10.3847/1538-4357/adb7e6}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {31}, shortjournal = {The Astrophys. J.}, title = {DDO 68-C: HST confirms yet another companion of the isolated dwarf galaxy DDO 68}, volume = {982}, year = {2025}, }
• (2025). Relight the candle: What happens to high-redshift massive quenched galaxies. ApJ, 982(1), 30. (www)

  @article{ , abstract = {A puzzling population of extremely massive quiescent galaxies at redshifts beyond z = 3 has recently been revealed by JWST and the Atacama Large Millimeter/submillimeter Array, some of them with stellar ages that show their quenching times to be as high as z = 6, while their stellar masses are already above 5 × 10 10 M ⊙ . These extremely massive yet quenched galaxies challenge our understanding of galaxy formation at the earliest stages. Using the hydrodynamical cosmological simulation suite Magneticum Pathfinder, we show that such massive quenched galaxies at high redshifts can be successfully reproduced with similar number densities as observed. The stellar masses, sizes, formation redshifts, and star formation histories of the simulated quenched galaxies match those determined with JWST. Following these quenched galaxies at z = 3.4 forward in time, we find 20% to be accreted onto a more massive structure by z = 2, and from the remaining 80% about 30% rejuvenate up to z = 2, another 30% stay quenched, and the remaining 40% rejuvenate on a very low level of star formation. Stars formed through rejuvenation are mostly formed on the outer regions of the galaxies, not in the centers. Furthermore, we demonstrate that the massive quenched galaxies do not reside in the most massive nodes of the cosmic web, but rather live in side nodes of approximately Milky Way halo mass. Even at z = 0, only about 10% end up in small-mass galaxy clusters, while most of the quenched galaxies at z = 3.4 end up in group-mass halos, with about 20% actually not even reaching 10 13 M ⊙ in halo mass.}, archive = {J_ApJ}, author = {Rhea-Silvia Remus and Lucas C. Kimmig}, doi = {10.3847/1538-4357/ad8b4b}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {30}, shortjournal = {The Astrophys. J.}, title = {Relight the candle: What happens to high-redshift massive quenched galaxies}, volume = {982}, year = {2025}, }
• (2025). The response of planetary atmospheres to the impact of icy comets. i. tidally locked exo-earths. ApJ, 982(1), 29. (www)

  @article{ , abstract = {Impacts by rocky and icy bodies are thought to have played a key role in shaping the composition of solar system objects, including the Earth's habitability. Hence, it is likely that they play a similar role in exoplanetary systems. We investigate how an icy cometary impact affects the atmospheric chemistry, climate, and composition of an Earth-like, tidally locked, terrestrial exoplanet, a prime target in the search for a habitable exoplanet beyond our solar system. We couple a cometary impact model, which includes thermal ablation and pressure driven breakup, with the 3D Earth system model WACCM6/CESM2 and use this model to investigate the effects of the water and thermal energy delivery associated with an R = 2.5 km pure water ice cometary impact on an Earth-like atmosphere. We find that water is the primary driver of longer timescale changes to the atmospheric chemistry and composition by acting as a source of opacity, cloud ice, and atmospheric hydrogen/oxygen. The water opacity drives heating at ∼5 × 10 −4 bar and cooling below, due to a decreased flux reaching the surface. The increase in atmospheric hydrogen and oxygen also drives an increase in the abundance of hydrogen/oxygen-rich molecules, with the exception of ozone, whose column density decreases by ∼10%. These atmospheric changes are potentially observable for ∼1–2 yr postimpact, particularly those associated with cloud ice scattering. They also persist, albeit at a much reduced level, to our quasi–steady state, suggesting that sustained bombardment or multiple large impacts have the potential to shape the composition and habitability of terrestrial exoplanets.}, archive = {J_ApJ}, author = {F. Sainsbury-Martinez and C. Walsh and G. Cooke}, doi = {10.3847/1538-4357/ad96ad}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {29}, shortjournal = {The Astrophys. J.}, title = {The response of planetary atmospheres to the impact of icy comets. i. tidally locked exo-earths}, volume = {982}, year = {2025}, }
• (2025). Revisiting the galactic winds in m82. II. development of multiphase outflows in simulations. ApJ, 982(1), 28. (www)

  @article{ , abstract = {We performed a suit of three-dimensional hydrodynamical simulations with a resolution of ~10 pc to investigate the development of multiphase galactic wind in M82. The star formation and related feedback processes are solved self-consistently using a sink particle method, rather than relying on various assumptions that were used in previous studies. Our simulations produce a starburst event lasting around 25 Myr, which has a total stellar mass of 1.62–3.34 × 10 8 M ⊙ , consistent with observational estimates. The total injected supernova energy is between 1.14 × 10 57 and 2.4 × 10 57 erg. Supernova feedback heats portions of the cool gas in the central disk to warm and hot phases, and then drives the gas in all three phases out, eventually forming multiphase outflows. These outflows can replicate key properties of the winds observed in M82, such as morphology, mass outflow rates of cool and hot phases, and X-ray emission flux, provided the gas return from star-forming clumps to the diffuse interstellar medium is implemented appropriately. The maximum mass outflow rate of all gas (hot) is about 6–12 (2–3) M ⊙ yr −1 at r ~ 4.0 kpc, corresponding to a mass loading factor of 2–4. However, the outflow velocities in our simulations are slower than observational estimates by ~20%–60%. The gas return process significantly influences the outflow properties, while the initial gas distribution in the nuclear region has a moderate effect. Yet, our results face some challenges in achieving convergence as the resolution increases. We discuss potential improvements to address these issues in future work.}, archive = {J_ApJ}, author = {Xue-Fu Li and Weishan Zhu and Tian-Rui Wang and Long-Long Feng}, doi = {10.3847/1538-4357/ada38c}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {28}, shortjournal = {The Astrophys. J.}, title = {Revisiting the galactic winds in m82. II. development of multiphase outflows in simulations}, volume = {982}, year = {2025}, }
• (2025). The physical origin of extreme emission line galaxies at high redshifts: Strong [O iii] emission lines produced by obscured active galactic nuclei. ApJ, 982(1), 27. (www)

  @article{ , abstract = {We present deep Subaru/FOCAS spectra for two extreme emission line galaxies (EELGs) at z ∼ 1 with strong [ O iii ] λ 5007 emission lines, exhibiting equivalent widths (EWs) of 290{5}_{-578}^{+946} Å and 200{0}_{-159}^{+188} Å, comparable to those of EELGs at high redshifts that are now routinely identified with JWST spectroscopy. Adding a similarly large [O iii ] EW ( 250{8}_{-689}^{+1487} Å) EELG found at z ∼ 2 in the JWST CEERS survey to our sample, we explore the physical origins of the large [O iii ] EWs of these three galaxies with the Subaru spectra and various public data including JWST/NIRSpec, NIRCam, and MIRI data. While there are no clear signatures of active galactic nuclei (AGNs) identified by the optical line diagnostics, we find that two out of two galaxies covered by the MIRI data show strong near-infrared excess in the spectral energy distributions (SEDs), indicating obscured AGNs. Because none of the three galaxies show clear broad H β lines, the upper limits on the flux ratios of broad H β to [O iii ] lines are small, ≲0.15 that are comparable with Seyfert 1.8–2.0 galaxies. We conduct Cloudy modeling with the stellar and AGN incident spectra, allowing a wide range of parameters, including metallicities and ionization parameters. We find that the large [O iii ] EWs are not self-consistently reproduced by the spectra of stars or unobscured AGNs, but obscured AGNs that efficiently produce O ++ ionizing photons with weak nuclear and stellar continua that are consistent with the SED shapes.}, archive = {J_ApJ}, author = {Chenghao Zhu and Yuichi Harikane and Masami Ouchi and Yoshiaki Ono and Masato Onodera and Shenli Tang and Yuki Isobe and Yoshiki Matsuoka and Toshihiro Kawaguchi and Hiroya Umeda and Kimihiko Nakajima and Yongming Liang and Yi Xu and Yechi Zhang and Dongsheng Sun and Kazuhiro Shimasaku and Jenny Greene and Kazushi Iwasawa and Kotaro Kohno and Tohru Nagao and Andreas Schulze and Takatoshi Shibuya and Miftahul Hilmi and Malte Schramm}, doi = {10.3847/1538-4357/adaf1b}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {27}, shortjournal = {The Astrophys. J.}, title = {The physical origin of extreme emission line galaxies at high redshifts: Strong [O iii] emission lines produced by obscured active galactic nuclei}, volume = {982}, year = {2025}, }
• (2025). The TRGB–SBF project. II. resolving the virgo cluster with JWST. ApJ, 982(1), 26. (www)

  @article{ , abstract = {The Virgo Cluster is the nearest substantial cluster of galaxies to the Milky Way and a cornerstone of the extragalactic distance scale. Here, we present JWST/NIRCam observations that simultaneously cover the cores and halos of 10 galaxies in and around the Virgo Cluster and are designed to perform simultaneous measurements of the tip of the red giant branch (TRGB) and surface brightness fluctuations (SBF). Seven of the targets are within the Virgo Cluster and where we are able to resolve some of the cluster's substructure, while an additional three provide important constraints on Virgo infall. The seven galaxies within Virgo itself all have SBF measurements from the Advanced Camera for Surveys Virgo Cluster Survey (ACSVCS). After adjusting the ACSVCS measurements for the offset from our new JWST TRGB measurements, we determine a distance to the Virgo Cluster of d = 16.17 ± 0.25 (stat) ± 0.47 (sys) Mpc. The work presented here is part of a larger program to develop a Population II distance scale through the TRGB and SBF that is completely independent of the prominent Cepheid + Type Ia supernova ladder. The TRGB distances to the galaxies presented here, when combined with future SBF measurements, will provide a crucial step forward for determining whether or not systematic errors can explain the well-known "Hubble tension" or if there is significant evidence for cracks in the ΛCDM model.}, archive = {J_ApJ}, author = {Gagandeep S. Anand and R. Brent Tully and Yotam Cohen and Edward J. Shaya and Dmitry I. Makarov and Lidia N. Makarova and Maksim I. Chazov and John P. Blakeslee and Michele Cantiello and Joseph B. Jensen and Ehsan Kourkchi and Gabriella Raimondo}, doi = {10.3847/1538-4357/adb399}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {26}, shortjournal = {The Astrophys. J.}, title = {The TRGB–SBF project. II. resolving the virgo cluster with JWST}, volume = {982}, year = {2025}, }
• (2025). Accretion-disk reflection in the seyfert 1 galaxy NGC 3783 as viewed by chandra grating spectroscopy. ApJ, 982(1), 25. (www)

  @article{ , abstract = {In active galactic nuclei, X-ray illumination of the accretion disk around a supermassive black hole (SMBH) results in the production of the K α fluorescent line of iron, which provides insights into accretion physics and SMBH spins. In this work, we studied X-ray reflection from the accretion disk in the Seyfert 1 galaxy NGC 3783 using all the data collected by the Chandra High Energy Transmission Grating Spectrometer. We used hardness-ratio diagrams to distinguish between different spectral states and conducted spectral analysis of all the multiepoch data sets, as well as the source in the observed spectral states. Our hardness analysis indicates that the source gradually evolved into a harder state (2013–2016) compared to the previous epochs (2000–2001). Our spectral modeling implies that the relativistically broadened iron emission from the innermost accretion disk is associated with a near-maximal SMBH spin ( a=0.9{8}_{-0.12}^{+0.02} ) in all the data sets, even though the hard state was present in 17% of them, and a consistent spin is also found in different spectral states. In addition, the narrow, bright Fe K α line from distant regions has an excess velocity of 62{0}_{-70}^{+80} km s −1 relative to the rest frame, implying that some distant layers of the disk could be twisted. Our results suggest that, despite long-term changes in the X-ray brightness of NGC 3783, likely caused by eclipsing material, the relativistic reflection can be constrained thanks to the substantial counts provided by the multiepoch observations, while a warped disk structure may be present.}, archive = {J_ApJ}, author = {A. Danehkar and W. N. Brandt}, doi = {10.3847/1538-4357/adb39c}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {25}, shortjournal = {The Astrophys. J.}, title = {Accretion-disk reflection in the seyfert 1 galaxy NGC 3783 as viewed by chandra grating spectroscopy}, volume = {982}, year = {2025}, }
• (2025). The molecular cloud life cycle. i. constraining h2 formation and dissociation rates with observations. ApJ, 982(1), 24. (www)

  @article{ , abstract = {Molecular clouds (MCs) are the birthplaces of new stars in galaxies. A key component of MCs are photodissociation regions (PDRs), where far-ultraviolet radiation plays a crucial role in determining the gas's physical and chemical state. Traditional PDR models assume a chemical steady state (CSS), where the rates of H 2 formation and photodissociation are balanced. However, real MCs are dynamic and can be out of CSS. In this study, we demonstrate that combining H 2 emission lines observed in the far-ultraviolet or infrared with column density observations can be used to derive the rates of H 2 formation and photodissociation. We derive analytical formulae that relate these rates to observable quantities, which we validate using synthetic H 2 line emission maps derived from the SILCC-Zoom hydrodynamical simulation. Our method estimates integrated H 2 formation and dissociation rates with an accuracy ≈30% (on top of the uncertainties in the observed H 2 emission maps and column densities). Our simulations, valid for column densities N ≤ 2 × 10 22 cm −2 , cover a wide dynamic range of H 2 formation and photodissociation rates, showing significant deviations from CSS, with 74% of the MC's mass deviating from CSS by a factor greater than 2. Our analytical formulae can effectively distinguish between regions in and out of CSS. When applied to actual H 2 line observations, our method can assess the chemical states of MCs, providing insights into their evolutionary stages and lifetimes. A NASA Small Explorer mission concept, Eos, will be proposed in 2025 and is specifically designed to conduct the types of observations outlined in this study.}, archive = {J_ApJ}, author = {Shmuel Bialy and Blakesley Burkhart and Daniel Seifried and Amiel Sternberg and Benjamin Godard and Mark R. Krumholz and Stefanie Walch and Erika Hamden and Thomas J. Haworth and Neal J. Turner and Min-Young Lee and Shuo Kong}, doi = {10.3847/1538-4357/adb3a6}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {24}, shortjournal = {The Astrophys. J.}, title = {The molecular cloud life cycle. i. constraining h2 formation and dissociation rates with observations}, volume = {982}, year = {2025}, }
• (2025). On the significance of rare objects at high redshift: The impact of cosmic variance. ApJ, 982(1), 23. (www)

  @article{ , abstract = {The discovery of extremely luminous galaxies at ultra-high redshifts ( z ≳ 8) has challenged galaxy formation models. Most analyses of this tension have not accounted for the variance due to field-to-field clustering, which causes the number counts of galaxies to vary greatly in excess of Poisson noise. This super-Poissonian variance is often referred to as cosmic variance. Since cosmic variance increases rapidly as a function of mass, redshift, and smaller observing areas, the most massive objects in deep JWST surveys are severely impacted by cosmic variance. We construct a simple model, including cosmic variance, to predict the distribution of the mass of the most massive galaxy for different surveys, which increases the tension with observations. The distributions differ significantly from previous predictions using the Extreme Value Statistics formalism, changing the position and shape of the distributions. We test our model using the UniverseMachine simulations, where the predicted effects of cosmic variance are clearly identifiable. We find that the high skew in the distributions of galaxy counts for typical deep surveys imply a high statistical variance on the cosmic variance itself. This impacts the calibration of the cosmic variance, as well as the expected mass of the most massive galaxy. We also find that the impact of cosmic variance dominates the impact of any realistic scatter in the stellar-to-halo-mass relation at z ≳ 12. It is therefore crucial to accurately account for the impact of cosmic variance in any analysis of tension between early extreme galaxies and galaxy formation models.}, archive = {J_ApJ}, author = {Christian Kragh Jespersen and Charles L. Steinhardt and Rachel S. Somerville and Christopher C. Lovell}, doi = {10.3847/1538-4357/adb422}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {23}, shortjournal = {The Astrophys. J.}, title = {On the significance of rare objects at high redshift: The impact of cosmic variance}, volume = {982}, year = {2025}, }
• (2025). VODKA-JWST: Synchronized growth of two supermassive black holes in a massive gas disk? a 3.8 kpc separation dual quasar at cosmic noon with the NIRSpec integral field unit. ApJ, 982(1), 22. (www)

  @article{ , abstract = {The search for dual supermassive black holes (SMBHs) is of immense interest in modern astrophysics. Galaxy mergers may fuel and produce SMBH pairs. Actively accreting SMBH pairs are observed as dual quasars, which are vital probes of SMBH growth. Dual quasars at cosmic noon are not well characterized. Gaia observations have enabled a novel technique to identify dual quasars at kiloparsec scales based on the small jitters of the light centroid as the two quasars vary stochastically. We present the first detailed study of a z = 2.17, 0 \mathop{.}\limits^{\unicode{x02033}} 46, 3.8 kpc separation dual quasar, J0749+2255, using JWST/NIRSpec integral field unit spectroscopy. Identified by Gaia, J0749+2255 is one of the most distant small-separation dual quasars known. We detect the faint ionized gas of the host galaxy, traced by the narrow H α emission. Line ratios indicate ionization from the two quasars and from intense star formation. Spectral analysis of the two quasars suggests that they have similar black hole properties, hinting at the possible synchronized accretion activity or lensed quasar images. Surprisingly, the ionized gas kinematics suggest a rotating disk rather than the disturbed system expected in a major gas-rich galaxy merger. Numerical simulations show that this is a plausible outcome of a major gas-rich galaxy merger several tens of Myr before coalescence. Whether J0749+2255 reflects an interesting phase of dual quasar evolution or is a lensed quasar remains unclear. Thus, this study underscores the challenges in definitively distinguishing between dual and lensed quasars, with observations supporting either scenario.}, archive = {J_ApJ}, author = {Yuzo Ishikawa and Nadia L. Zakamska and Yue Shen and Xin Liu and Yu-Ching Chen and Hsiang-Chih Hwang and Andrey Vayner and David S. N. Rupke and Sylvain Veilleux and Dominika Wylezalek and Arran C. Gross and Swetha Sankar and Nadiia Diachenko}, doi = {10.3847/1538-4357/adb4ee}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {22}, shortjournal = {The Astrophys. J.}, title = {VODKA-JWST: Synchronized growth of two supermassive black holes in a massive gas disk? a 3.8 kpc separation dual quasar at cosmic noon with the NIRSpec integral field unit}, volume = {982}, year = {2025}, }
• (2025). Application of resolved low-J multi-CO line modeling with RADEX to constrain the molecular gas properties in the starburst m82. ApJ, 982(1), 21. (www)

  @article{ , abstract = {The distribution and physical conditions of molecular gas are closely linked to star formation and the subsequent evolution of galaxies. Emission from carbon monoxide (CO) and its isotopologues traces the bulk of molecular gas and provides constraints on the physical conditions through their line ratios. However, a comprehensive understanding of how the particular choice of line modeling approach impacts derived molecular properties remains incomplete. Here, we study the nearby starburst galaxy M82, known for its intense star formation and molecular emission, using the large set of available multi-CO line observations. We present high-resolution (∼85 pc) emission of seven CO isotopologue lines, including 12 CO, 13 CO, and C 18 O from the J = 1–0, 2–1, and 3–2 transitions. Using RADEX for radiative transfer modeling, we analyze M82's molecular properties with (i) a one-zone model and (ii) a variable density model, comparing observed and simulated emissions via a minimum χ 2 analysis. We find that inferred gas conditions—kinetic temperature and density—are consistent across models, with minimal statistical differences. However, due to their low critical densities (<10 4 cm −3 ), low- J CO isotopologue lines do not effectively probe higher-density gas prevalent in starburst environments like that of M82. Our results further imply that this limitation extends to high-redshift ( z ⪆ 1) galaxies with similar conditions, where low- J CO lines are inadequate for density constraints. Future studies of extreme star-forming regions like M82 will require higher- J CO lines or alternative molecular tracers with higher critical densities.}, archive = {J_ApJ}, author = {Valencia Zhang and Jakob den Brok and Qizhou Zhang and Yu-Hsuan Teng and María J. Jiménez-Donaire and Eric W. Koch and Antonio Usero and Fabian Walter and Leindert Boogaard and Craig Yanitski and Cosima Eibensteiner and Ivana Bešlic and Juan Luis Verbena}, doi = {10.3847/1538-4357/adb579}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {21}, shortjournal = {The Astrophys. J.}, title = {Application of resolved low-J multi-CO line modeling with RADEX to constrain the molecular gas properties in the starburst m82}, volume = {982}, year = {2025}, }
• (2025). The initial-to-final mass relation of white dwarfs in intermediate-separation binaries. ApJ, 982(1), 20. (www)

  @article{ , abstract = {We examine the applicability of the initial-to-final mass relation (IFMR) for white dwarfs (WDs) in intermediate-separation binary systems (∼1 au), using astrometric binaries identified in open clusters from Gaia DR3. A careful analysis of the astrometric orbits and spectral energy distributions isolates 33 main-sequence (MS) stars with highly likely WD companions. By combining cluster age estimates, dynamically measured WD masses, and, where available, WD cooling temperatures, we derive progenitor masses for 26 WD candidates. Our analysis suggests the presence of two distinct WD populations: (i) low-mass WDs, likely shaped by binary interactions during the progenitor's red giant phase; and (ii) "spender" WDs, which experienced higher-than-expected mass loss and have progenitor masses above the IFMR predictions. The rest of the candidates, referred to as the "others," represent systems with inconclusive formation mechanisms. We suggest that at least some of these systems might be hierarchical triples, where the companion to the MS is a double WD or a double-WD merger product. However, follow-up studies are required to determine the nature of each case. These results highlight significant deviations from the IFMR derived for isolated WDs, emphasizing the role of binary evolution. Follow-up observations, particularly in the far-ultraviolet, are crucial for refining these findings and advancing our understanding of mass transfer processes and binary evolution pathways.}, archive = {J_ApJ}, author = {Oren Ironi and Sagi Ben-Ami and Na’ama Hallakoun and Sahar Shahaf}, doi = {10.3847/1538-4357/adb5f2}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {20}, shortjournal = {The Astrophys. J.}, title = {The initial-to-final mass relation of white dwarfs in intermediate-separation binaries}, volume = {982}, year = {2025}, }
• (2025). Signature of strange star as the central engine of GRB 240529A. ApJ, 982(1), 19. (www)

  @article{ , abstract = {GRB 240529A is a long-duration gamma-ray burst (GRB) whose light curve of prompt emission is composed of a triple-episode structure, separated by quiescent gaps of tens to hundreds of seconds. More interestingly, its X-ray light curve of afterglow exhibits two plateau emissions, namely, an internal plateau emission that is smoothly connected with a ∼ t −0.1 segment and followed by a ∼ t −2 power-law decay. The three episodes in the prompt emission, together with two plateau emissions in X-ray, are unique in the Swift era. They are very difficult to explain with the standard internal/external shock model by invoking a black hole central engine. However, it could be consistent with the prediction of a supramassive magnetar as the central engine, the physical process of phase transition from a magnetar to a strange star, as well as the cooling and spin-down of the strange star. In this paper, we propose that the first- and second-episode emissions in the prompt gamma ray of GRB 240529A are from the jet emission of a massive star collapsing into a supramassive magnetar and the reactivity of the central engine, respectively. Then, the third-episode emission of the prompt is attributed to the phase transition from a magnetar to a strange star. Finally, the first and second plateau emissions of the X-ray afterglow are powered by the cooling and spin-down of the strange star, respectively. The observational data of each component of GRB 240529A are roughly coincident with the estimations of the above physical picture.}, archive = {J_ApJ}, author = {Xiao Tian and HouJun Lü and WenJun Tan and ShaoLin Xiong and HaoYu Yuan and WenYuan Yu and ShuQing Zhong and WenLong Zhang and EnWei Liang}, doi = {10.3847/1538-4357/adb711}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {19}, shortjournal = {The Astrophys. J.}, title = {Signature of strange star as the central engine of GRB 240529A}, volume = {982}, year = {2025}, }
• (2025). Quenching and recovery of persistent X-ray emission during a superburst in 4U 1820–30. ApJ, 982(1), 18. (www)

  @article{ , abstract = {We report the superburst from 4U 1820–30 in 2021 observed by the Monitor of All-sky X-ray Image and Neutron star Interior Composition Explorer (NICER). During the tail of the superburst, we found that the NICER light curve unexpectedly increased from 1080 to 2204 counts s −1 over 6.89 hr. From the time-resolved superburst spectra, we estimated the burst decay time of ≈2.5 hr, the ignition column depth of ≈0.3 × 10 12 g cm −2 , the energy release per unit mass of ≈2.4 × 10 17 erg g −1 , the fluence of ≈4.1 × 10 −4 erg cm −2 , and the total energy release of ≈3.5 × 10 42 erg. Notably, we found a gradual increase in the Comptonization flux from 8.9 × 10 −10 erg s −1 cm −2 to the preburst level during the superburst. This increase can be interpreted as a consequence of superburst radiation depleting the inner accretion disk, leading to a near-complete quenching of the persistent emission. As the burst radiation decayed, the inner accretion disk gradually returned to its preburst state, as evidenced by the best-fit spectral parameters. Additionally, we observed a prominent absorption line that exhibited a gravitational redshift, shifting from 4.15 to 3.62 keV during the recovery phase of persistent emission. This absorption feature likely originates from the inner accretion disk rather than from burst emission on the neutron star (NS) surface. The observed changes in the absorption line energy suggest that the inner disk approached the NS to a distance as close as ≈17 km.}, archive = {J_ApJ}, author = {Zhijiao Peng and Zhaosheng Li and Yuanyue Pan and Tao Fu and Wenhui Yu and Yupeng Chen and Shu Zhang and Maurizio Falanga and Shuang-Nan Zhang}, doi = {10.3847/1538-4357/adb726}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {18}, shortjournal = {The Astrophys. J.}, title = {Quenching and recovery of persistent X-ray emission during a superburst in 4U 1820–30}, volume = {982}, year = {2025}, }
• (2025). The roman microlensing survey: Confirmation or refutation of gas giant exoplanet formation theories. ApJ, 982(1), 17. (www)

  @article{ , abstract = {Exoplanet research has moved from the discovery of new classes of planets toward creating a census of exoplanet population demographics across the spectrum of exoplanet and host star masses. This census will constrain possible exoplanet formation and evolution theories. Direct imaging and ground-based microlensing surveys excel at detecting long-period exoplanets. The Roman Space Telescope microlensing survey (RMS) will help complete the census by possibly discovering hundreds of long-period and free-floating exoplanets. Long-period gas giants are difficult to form by the classic core-accretion mechanism, whereas the gas disk gravitational instability (GDGI) mechanism can form gas giants at distances of 10 au and beyond for AFGKM host stars. The Enzo 2.6 adaptive mesh refinement three-dimensional hydrodynamics code is used to model the formation of gas giant protoplanets by GDGI around solar-mass protostars, for future comparison with the RMS, which will provide convincing evidence about whether GDGI is needed to explain exoplanet demographics. Previous Enzo models have shown that a robust GDGI is able to form enough gas giants in a single system to result in the ejection of a significant fraction within ∼2000 yr, a likely source of free-floating exoplanets. The present models investigate the GDGI outcomes for a larger range of initial protoplanetary disk masses and outer disk temperatures than in the previous work of A. P. Boss, resulting in the formation of abundant substellar companions with masses in the range of ∼0.1 to ∼100 M Jup on orbits ranging from ∼3 to ∼30 au.}, archive = {J_ApJ}, author = {Alan P. Boss}, doi = {10.3847/1538-4357/adb728}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {17}, shortjournal = {The Astrophys. J.}, title = {The roman microlensing survey: Confirmation or refutation of gas giant exoplanet formation theories}, volume = {982}, year = {2025}, }
• (2025). Unsupervised machine learning for classifying CHIME fast radio bursts and investigating empirical relations. ApJ, 982(1), 16. (www)

  @article{ , abstract = {Fast radio bursts (FRBs) are highly energetic millisecond-duration astrophysical phenomena typically categorized as repeaters or nonrepeaters. However, observational limitations may result in misclassifications, potentially leading to a higher proportion of repeaters than currently identified. In this study, we leverage unsupervised machine learning techniques to classify FRBs using data from the CHIME/FRB catalogs, including both the first catalog and a recent repeater catalog. By employing Uniform Manifold Approximation and Projection for dimensionality reduction and clustering algorithms ( k -means and Hierarchical Density-Based Spatial Clustering of Applications with Noise), we successfully segregate repeaters and nonrepeaters into distinct clusters, identifying over 100 potential repeater candidates. Our analysis reveals several empirical relations within the clusters, including the {\rm{log}}\,{\rm{\Delta }}{t}_{sc}-{\rm{log}}\,{\rm{\Delta }}{t}_{rw} , {\rm{log}}\,{\rm{\Delta }}{t}_{sc}-{\rm{log}}\,{T}_{B} , and r – γ correlations, where Δ t sc , Δ t rw , T B , r , and γ represent the scattering time, rest-frame width, brightness temperature, spectral running, and spectral index, respectively. The Chow test results reveal that while some repeaters and nonrepeaters share similar empirical relationships, the overall distinctions between the two groups remain significant, reinforcing the classification of FRBs into repeaters and nonrepeaters. These findings provide new insights into the physical properties and emission mechanisms of FRBs. This study demonstrates the effectiveness of unsupervised learning in classifying FRBs and identifying potential repeaters, paving the way for more precise investigations into their origins and applications in cosmology. Future improvements in observational data and machine learning methodologies are expected to further enhance our understanding of FRBs.}, archive = {J_ApJ}, author = {Da-Chun Qiang and Jie Zheng and Zhi-Qiang You and Sheng Yang}, doi = {10.3847/1538-4357/adb72b}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {16}, shortjournal = {The Astrophys. J.}, title = {Unsupervised machine learning for classifying CHIME fast radio bursts and investigating empirical relations}, volume = {982}, year = {2025}, }
• (2025). Measurement and modeling of polarized atmosphere at the south pole with SPT-3G. ApJ, 982(1), 15. (www)

  @article{ , abstract = {We present the detection and characterization of fluctuations in linearly polarized emission from the atmosphere above the South Pole. These measurements make use of data from the SPT-3G receiver on the South Pole Telescope in three frequency bands centered at 95, 150, and 220 GHz. We use the cross-correlation between detectors to produce an unbiased estimate of the power in Stokes I , Q , and U parameters on large angular scales. Our results are consistent with the polarized signal being produced by the combination of Rayleigh scattering of thermal radiation from the ground and thermal emission from a population of horizontally aligned ice crystals with an anisotropic distribution described by Kolmogorov turbulence. The measured spatial scaling, frequency scaling, and elevation dependence of the polarized emission are explained by this model. Polarized atmospheric emission has the potential to significantly impact observations on the large angular scales being targeted by searches for inflationary B-mode CMB polarization. We present the distribution of measured angular power spectrum amplitudes in Stokes Q and I for 4 yr of Austral winter observations, which can be used to simulate the impact of atmospheric polarization and intensity fluctuations at the South Pole on a specified experiment and observation strategy. We present a mitigation strategy that involves both downweighting significantly contaminated observations and subtracting a polarized atmospheric signal from the 150 GHz band maps. In observations with the SPT-3G instrument, the polarized atmospheric signal is a well-understood and subdominant contribution to the measured noise after implementing the mitigation strategies described here.}, archive = {J_ApJ}, author = {A. Coerver and J. A. Zebrowski and S. Takakura and W. L. Holzapfel and P. A. R. Ade and A. J. Anderson and Z. Ahmed and B. Ansarinejad and M. Archipley and L. Balkenhol and D. Barron and K. Benabed and A. N. Bender and B. A. Benson and F. Bianchini and L. E. Bleem and F. R. Bouchet and L. Bryant and E. Camphuis and J. E. Carlstrom and T. W. Cecil and C. L. Chang and P. Chaubal and P. M. Chichura and A. Chokshi and T.-L. Chou and T. M. Crawford and A. Cukierman and C. Daley and T. de Haan and K. R. Dibert and M. A. Dobbs and A. Doussot and D. Dutcher and W. Everett and C. Feng and K. R. Ferguson and K. Fichman and A. Foster and S. Galli and A. E. Gambrel and R. W. Gardner and F. Ge and N. Goeckner-Wald and R. Gualtieri and F. Guidi and S. Guns and N. W. Halverson and E. Hivon and G. P. Holder and J. C. Hood and A. Hryciuk and N. Huang and F. Kéruzoré and A. R. Khalife and L. Knox and M. Korman and K. Kornoelje and C.-L. Kuo and A. T. Lee and K. Levy and A. E. Lowitz and C. Lu and A. Maniyar and E. S. Martsen and F. Menanteau and M. Millea and J. Montgomery and Y. Nakato and T. Natoli and G. I. Noble and V. Novosad and Y. Omori and S. Padin and Z. Pan and P. Paschos and K. A. Phadke and A. W. Pollak and K. Prabhu and W. Quan and M. Rahimi and A. Rahlin and C. L. Reichardt and M. Rouble and J. E. Ruhl and E. Schiappucci and G. Smecher and J. A. Sobrin and A. A. Stark and J. Stephen and A. Suzuki and C. Tandoi and K. L. Thompson and B. Thorne and C. Trendafilova and C. Tucker and C. Umilta and J. D. Vieira and A. Vitrier and Y. Wan and G. Wang and N. Whitehorn and W. L. K. Wu and V. Yefremenko and M. R. Young}, doi = {10.3847/1538-4357/ada35d}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {15}, shortjournal = {The Astrophys. J.}, title = {Measurement and modeling of polarized atmosphere at the south pole with SPT-3G}, volume = {982}, year = {2025}, }
• (2025). On the average ultraviolet emission-line spectra of high-redshift galaxies: Hot and cold, carbon-poor, nitrogen modest, and oozing ionizing photons. ApJ, 982(1), 14. (www)

  @article{ , abstract = {We determine the spectroscopic properties of ≃1000 ostensibly star-forming galaxies at redshifts ( z = 4–10) using prism spectroscopy from JWST/NIRSpec. With rest-wavelength coverage between Ly α and [S ii ] in the optical, we stack spectra as a function of nebular conditions, and compare UV spectral properties with stellar age. This reveals UV lines of N iii ], N iv ], C iii ], C iv , He ii , and O iii ] in the average high- z galaxy. All of the UV lines are more intense in younger starbursts. We measure electron temperatures from the collisionally excited [O iii ] line ratios, finding T e = 18,000–22,000 K for the O ++ regions. We also detect a significant nebular Balmer jump, from which we estimate only T e = 8000–13,000 K. Accounting for typical temperature offsets between zones bearing doubly and singly ionized oxygen, these two temperatures remain discrepant by around 40%. We use the [O iii ] temperatures to estimate abundances of carbon, nitrogen, and oxygen. We find that log(C/O) is consistently ≃ −1, with no evolution of C/O with metallicity or stellar age. The average spectra are mildly enhanced in nitrogen, with higher N/O than low- z starbursts, but are less enhanced than samples of recently reported, high- z , extreme galaxies that show N iii ] and N iv ] emission in the UV. Whatever processes produce the N-enhancement in the individual galaxies must also be ongoing, at lower levels, in the median galaxy in the early Universe. The strongest starbursts are a source of significant ionizing emission: ionizing photon production efficiencies reach 10 25.7 Hz erg −1 , and show multiple signatures of high Lyman continuum escape, including Mg ii escape fractions nearing 100%, significant deficits in [S ii ] emission, high degrees of ionization, and blue UV colors.}, archive = {J_ApJ}, author = {Matthew J. Hayes and Alberto Saldana-Lopez and Annalisa Citro and Bethan L. James and Matilde Mingozzi and Claudia Scarlata and Zorayda Martinez and Danielle A. Berg}, doi = {10.3847/1538-4357/adaea1}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {14}, shortjournal = {The Astrophys. J.}, title = {On the average ultraviolet emission-line spectra of high-redshift galaxies: Hot and cold, carbon-poor, nitrogen modest, and oozing ionizing photons}, volume = {982}, year = {2025}, }
• (2025). A data-driven m dwarf model and detailed abundances for ​​​​​​∼17,000 m dwarfs in SDSS-V. ApJ, 982(1), 13. (www)

  @article{ , abstract = {The cool temperatures of M dwarf atmospheres enable complex molecular chemistry, making robust characterization of M dwarf compositions a long-standing challenge. Recent modifications to spectral synthesis pipelines have enabled more accurate modeling of M dwarf atmospheres, but these methods are too slow for characterizing more than a handful of stars at a time. Data-driven methods such as The Cannon are viable alternatives, and can harness the information content of many M dwarfs from large spectroscopic surveys. Here, we train The Cannon on M dwarfs with FGK binary companions from the Sloan Digital Sky Survey-V/Milky Way Mapper (SDSS-V/MWM), with spectra from the Apache Point Observatory Galactic Evolution Experiment. The FGK-M pairs are assumed to be chemically homogeneous and span −0.56 < [Fe/H] < 0.31 dex. The resulting model is capable of inferring M dwarf T eff and elemental abundances for Fe, Mg, Al, Si, C, N, O, Ca, Ti, Cr, and Ni with median uncertainties of 13 K and 0.018–0.029 dex, respectively. We test the model by verifying that it reproduces the reported abundance values of M dwarfs in open clusters and benchmark M dwarf data sets, as well as the expected metallicity trends from stellar evolution. We apply the model to 16,590 M dwarfs in SDSS-V/MWM and provide their detailed abundances in our accompanying catalog.}, archive = {J_ApJ}, author = {Aida Behmard and Melissa K. Ness and Andrew R. Casey and Ruth Angus and Katia Cunha and Diogo Souto and Yuxi(Lucy) Lu and Jennifer A. Johnson}, doi = {10.3847/1538-4357/adaf1f}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {13}, shortjournal = {The Astrophys. J.}, title = {A data-driven m dwarf model and detailed abundances for ​​​​​​∼17,000 m dwarfs in SDSS-V}, volume = {982}, year = {2025}, }
• (2025). Luminous type II short-plateau SN 2023ufx: Asymmetric explosion of a partially stripped massive progenitor. ApJ, 982(1), 12. (www)

  @article{ , abstract = {We present supernova (SN) 2023ufx, a unique Type IIP SN with the shortest known plateau duration ( t PT ∼ 47 days), a luminous V -band peak ( M V = −​​​​​​18.42 ± 0.08 mag), and a rapid early decline rate ( s 1 = 3.47 ± 0.09 mag (50 days) −1 ). By comparing observed photometry to a hydrodynamic MESA+STELLA model grid, we constrain the progenitor to be a massive red supergiant with M ZAMS ∼ 19–25 M ⊙ . Independent comparisons with nebular spectral models also suggest an initial He-core mass of ∼6 M ⊙ , and thus a massive progenitor. For a Type IIP, SN 2023ufx produced an unusually high amount of nickel ( 56 Ni) ∼0.14 ± 0.02 M ⊙ , during the explosion. We find that the short plateau duration in SN 2023ufx can be explained with the presence of a small hydrogen envelope ( {M}_{{{\rm{H}}}_{\mathrm{env}}} ∼ 1.2 M ⊙ ), suggesting partial stripping of the progenitor. About ∼0.09 M ⊙ of circumstellar material through mass loss from late-time stellar evolution of the progenitor is needed to fit the early time (≲10 days) pseudo-bolometric light curve. Nebular line diagnostics of broad and multipeak components of [O i ] λλ 6300, 6364, H α , and [Ca ii ] λλ 7291, 7323 suggest that the explosion of SN 2023ufx could be inherently asymmetric, preferentially ejecting material along our line of sight.}, archive = {J_ApJ}, author = {Aravind P. Ravi and Stefano Valenti and Yize Dong and Daichi Hiramatsu and Stan Barmentloo and Anders Jerkstrand and K. Azalee Bostroem and Jeniveve Pearson and Manisha Shrestha and Jennifer E. Andrews and David J. Sand and Griffin Hosseinzadeh and Michael Lundquist and Emily Hoang and Darshana Mehta and Nicolás Meza Retamal and Aidan Martas and Saurabh W. Jha and Daryl Janzen and Bhagya Subrayan and D. Andrew Howell and Curtis McCully and Joseph Farah and Megan Newsome and Estefania Padilla Gonzalez and Giacomo Terreran and Moira Andrews and Alexei V. Filippenko and Thomas G. Brink and Weikang Zheng and Yi Yang and Jozsef Vinkó and J. Craig Wheeler and Nathan Smith and Jeonghee Rho and Réka Könyves-Tóth and Claudia P. Gutiérrez}, doi = {10.3847/1538-4357/adb0bb}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {12}, shortjournal = {The Astrophys. J.}, title = {Luminous type II short-plateau SN 2023ufx: Asymmetric explosion of a partially stripped massive progenitor}, volume = {982}, year = {2025}, }
• (2025). Diverse rotation curves of galaxies in a simulated universe: The observed dependence on stellar mass and morphology reproduced. ApJ, 982(1), 11. (www)

  @article{ , abstract = {We use the IllustrisTNG cosmological hydrodynamical simulation to study the rotation curves of galaxies in the local universe. To do that, we first select the galaxies with 9.4 < \mathrm{log}({M}_{{\rm{star}}}/{M}_{\odot }) < 11.5 to make a sample comparable to that of SDSS/MaNGA observations. We then construct the 2D line-of-sight velocity map and conduct the fit to determine the rotational velocity and the slope of the rotation curve in the outer region ( R t < r < 3 × r half,* ). The outer slopes of the simulated galaxies show diverse patterns that are dependent on morphology and stellar mass. The outer slope increases as galaxies are more disky, and decreases as galaxies are more massive, except for the very massive early-type galaxies. The outer slope of the rotation curves shows a correlation with the dark matter fraction, slightly better than for the gas mass fraction. Our study demonstrates that the observed dependence of galaxy rotation curves on morphology and stellar mass can be successfully reproduced in cosmological simulations, and provides a hint that dark matter plays an important role in shaping the rotation curve. The sample of simulated galaxies in this study could serve as an important test bed for the subsequent study tracing galaxies back in time, enabling a deeper understanding of the physical origin behind the diverse rotation curves.}, archive = {J_ApJ}, author = {Daeun Jeong and Ho Seong Hwang and Haeun Chung and Yongmin Yoon}, doi = {10.3847/1538-4357/adb1be}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {11}, shortjournal = {The Astrophys. J.}, title = {Diverse rotation curves of galaxies in a simulated universe: The observed dependence on stellar mass and morphology reproduced}, volume = {982}, year = {2025}, }
• (2025). Tripling the census of dwarf AGN candidates using DESI early data. ApJ, 982(1), 10. (www)

  @article{ , abstract = {Using early data from the Dark Energy Spectroscopic Instrument (DESI) survey, we search for active galactic nuclei (AGN) signatures in 410,757 line-emitting galaxies. By employing the BPT emission-line ratio diagnostic diagram, we identify AGNs in 75,928/296,261 (≈25.6%) high-mass ( \mathrm{log}({M}_{\star }/{M}_{\odot })\,\gt 9.5) and 2444/114,496 (≈2.1%) dwarf ( \mathrm{log}({M}_{\star }/{M}_{\odot })\,\leqslant 9.5) galaxies. Of these AGN candidates, 4181 sources exhibit a broad H α component, allowing us to estimate their BH masses via virial techniques. This study more than triples the census of dwarf AGNs and doubles the number of intermediate-mass black hole ( M BH ≤ 10 6 M ⊙ ) candidates, spanning a broad discovery space in stellar mass (7 \lt \mathrm{log}({M}_{\star }/{M}_{\odot })\,\lt 12) and redshift (0.001 < z < 0.45). The observed AGN fraction in dwarf galaxies (≈2.1%) is nearly four times higher than prior estimates, primarily due to DESI's smaller fiber size, which enables the detection of lower-luminosity dwarf AGN candidates. We also extend the M BH – M ⋆ scaling relation down to {\rm{log}}({M}_{\star }/{M}_{\odot })\,\approx 8.5 and \mathrm{log}({M}_{\mathrm{BH}}/{M}_{\odot })\,\approx 4.4, with our results aligning well with previous low-redshift studies. The large statistical sample of dwarf AGN candidates from current and future DESI releases will be invaluable for enhancing our understanding of galaxy evolution at the low-mass end of the galaxy mass function.}, archive = {J_ApJ}, author = {Ragadeepika Pucha and S. Juneau and Arjun Dey and M. Siudek and M. Mezcua and J. Moustakas and S. BenZvi and K. Hainline and R. Hviding and Yao-Yuan Mao and D. M. Alexander and R. Alfarsy and C. Circosta and Wei-Jian Guo and V. Manwadkar and P. Martini and B. A. Weaver and J. Aguilar and S. Ahlen and D. Bianchi and D. Brooks and R. Canning and T. Claybaugh and K. Dawson and A. de la Macorra and Biprateep Dey and P. Doel and A. Font-Ribera and J. E. Forero-Romero and E. Gaztañaga and S. Gontcho A Gontcho and G. Gutierrez and K. Honscheid and R. Kehoe and S. E. Koposov and A. Lambert and M. Landriau and L. Le Guillou and A. Meisner and R. Miquel and F. Prada and G. Rossi and E. Sanchez and D. Schlegel and M. Schubnell and H. Seo and D. Sprayberry and G. Tarlé and H. Zou}, doi = {10.3847/1538-4357/adb1dd}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {10}, shortjournal = {The Astrophys. J.}, title = {Tripling the census of dwarf AGN candidates using DESI early data}, volume = {982}, year = {2025}, }
• (2025). A 3D simulation of a type II-P supernova: From core bounce to beyond shock breakout. ApJ, 982(1), 9. (www)

  @article{ , abstract = {In order to better connect core-collapse supernova (CCSN) theory with its observational signatures, we have developed a simulation pipeline from the onset of the core collapse to beyond shock breakout from the stellar envelope. Using this framework, we present a 3D simulation study from 5 s to over 5 days following the evolution of a 17 M ⊙ progenitor, exploding with ∼10 51 erg of energy and ∼0.1 M ⊙ of 56 Ni ejecta. The early explosion is highly asymmetric, expanding most prominently along the southern hemisphere. This early asymmetry is preserved to shock breakout, ∼1 day later. Breakout itself evinces strong angle-dependence, with as much as 1 day delay in the shock breakout by direction. The nickel ejecta closely tail the forward shock, with velocities at the breakout as high as ∼7000 km s −1 . A delayed reverse shock forming at the H/He interface on hour timescales leads to the formation of Rayleigh–Taylor instabilities, fast-moving nickel bullets, and almost complete mixing of the metal core into the hydrogen envelope. For the first time, we illustrate the angle-dependent emergent broadband and bolometric light curves from simulations evolved in 3D in entirety, continuing through hydrodynamic shock breakout from a CCSN model of a massive stellar progenitor evolved with detailed, late-time neutrino microphysics and transport. Our case study of a single progenitor underscores that 3D simulations generically produce the cornucopia of observed asymmetries and features in CCSNe observations, while establishing the methodology to study this problem in breadth.}, archive = {J_ApJ}, author = {David Vartanyan and Benny T.-H. Tsang and Daniel Kasen and Adam Burrows and Tianshu Wang and Lizzy Teryoshin}, doi = {10.3847/1538-4357/adb1e4}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {9}, shortjournal = {The Astrophys. J.}, title = {A 3D simulation of a type II-P supernova: From core bounce to beyond shock breakout}, volume = {982}, year = {2025}, }
• (2025). Where is the supervirial gas? II. insight from the survey of galactic sightlines. ApJ, 982(1), 8. (www)

  @article{ , abstract = {Recent observations have revealed a supervirial temperature gas phase at log( T /K) ∼ 7 in the Milky Way, challenging existing galaxy formation models. This hot gas phase was discovered toward extragalactic absorption sightlines and blank-sky emission fields, both at high Galactic latitudes. The location of this hot component is unknown; is it in the extended circumgalactic medium (CGM) or in the interstellar medium (ISM) instead? We analyzed X-ray spectra from Chandra's High-Energy Transmission Grating observations of 27 Galactic X-ray binaries (XRBs) to investigate whether the hot gas component is present in the ISM. We searched for absorption lines of S xvi K α , Si xiv K α , and Ne x K α , which are the telltale signatures of the hot gas and which have been detected toward extragalactic sightlines. Of the 27 targets, these lines were detected in the spectra of only 7, with two sources displaying broad line features likely intrinsic to the XRB systems. Additionally, most of the detected lines are time variable, reinforcing their likely association with the XRBs. Our results suggest that the supervirial temperature gas is not a widespread component of the ISM but may instead be located in extraplanar regions or the extended CGM, which aligns with some recent simulation results.}, archive = {J_ApJ}, author = {Manami Roy and Smita Mathur and Sanskriti Das and Armando Lara-DI and Yair Krongold and Anjali Gupta}, doi = {10.3847/1538-4357/adb3a5}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {8}, shortjournal = {The Astrophys. J.}, title = {Where is the supervirial gas? II. insight from the survey of galactic sightlines}, volume = {982}, year = {2025}, }
• (2025). The ultraviolet slopes of early universe galaxies: The impact of bursty star formation, dust, and nebular continuum emission. ApJ, 982(1), 7. (www)

  @article{ , abstract = {JWST has enabled the detection of the ultraviolet (UV) continuum of galaxies at z > 10, revealing extremely blue, potentially dust-free galaxies. However, interpreting UV spectra is complicated by the well-known degeneracy between stellar ages, dust reddening, and nebular continuum. The main goal of this paper is to develop a theoretical model for the relationship between galaxy UV slopes ( β ), bursty star formation histories, dust evolution, and nebular contributions using cosmological zoom-in simulations. We build a layered model where we simulate increasingly complex physics, including the impact of (i) unattenuated intrinsic stellar populations, (ii) reddened populations using a new on-the-fly evolving dust model, and (iii) populations including dust and nebular continuum. Unattenuated stellar populations with no nebular emission exhibit a diverse range of intrinsic UV slopes ( β 0 ≈ −3 → −2.2), with an inverse correlation between UV slope and specific star formation rate. When including dust, our model galaxies demonstrate a rapid rise in dust obscuration between z ≈ 8 and 10. This increase in dust mass is due to high grain–grain shattering rates, and enhanced growth per unit dust mass in very small grains, resulting in UV-detected galaxies at z ∼ 12 descending into Atacama Large Millimeter/submillimeter Array–detectable galaxies by z ∼ 6. The rapid rise in dust content at z ≈ 8–10 leads to a systematic reddening of the UV slopes during this redshift range. Nebular continuum further reddens UV slopes by a median Δ β neb ≈ 0.2–0.4, though notably the highest-redshift galaxies ( z ≈ 12) are insufficiently blue compared to observations; this may imply an evolving escape fraction from H ii regions with redshift.}, archive = {J_ApJ}, author = {Desika Narayanan and Daniel P. Stark and Steven L. Finkelstein and Paul Torrey and Qi Li and Fergus Cullen and Micheal W. Topping and Federico Marinacci and Laura V. Sales and Xuejian Shen and Mark Vogelsberger}, doi = {10.3847/1538-4357/adb41c}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {7}, shortjournal = {The Astrophys. J.}, title = {The ultraviolet slopes of early universe galaxies: The impact of bursty star formation, dust, and nebular continuum emission}, volume = {982}, year = {2025}, }
• (2025). The evolution of hypervelocity supernova survivors and the outcomes of interacting double white dwarf binaries. ApJ, 982(1), 6. (www)

  @article{ , abstract = {The recent prediction and discovery of hypervelocity supernova survivors has provided strong evidence that the "dynamically driven double-degenerate double-detonation" (D 6 ) Type Ia supernova scenario occurs in nature. In this model, the accretion stream from the secondary white dwarf (WD) in a double WD binary strikes the primary WD violently enough to trigger a helium shell detonation, which in turn triggers a carbon/oxygen core detonation. If the secondary WD survives the primary's explosion, it will be flung away as a hypervelocity star. While previous work has shown that the hotter observed D 6 stars can be broadly understood as secondaries whose outer layers have been heated by their primaries' explosions, the properties of the cooler D 6 stars have proven difficult to reproduce. In this paper, we show that the cool D 6 stars can be explained by the Kelvin–Helmholtz contraction of helium or carbon/oxygen WDs that underwent significant mass loss and core heating prior to and during the explosion of their WD companions. We find that the current population of known D 6 candidates is consistent with ∼2% of Type Ia supernovae leaving behind a hypervelocity surviving companion. We also calculate the evolution of hot, low-mass oxygen/neon stars and find reasonable agreement with the properties of the LP 40–365 class of hypervelocity survivors, suggesting that these stars are the kicked remnants of near-Chandrasekhar-mass oxygen/neon WDs that were partially disrupted by oxygen deflagrations. We use these results as motivation for schematic diagrams showing speculative outcomes of interacting double WD binaries, including long-lived merger remnants, Type Ia supernovae, and several kinds of peculiar transients.}, archive = {J_ApJ}, author = {Ken J. Shen}, doi = {10.3847/1538-4357/adb42e}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {6}, shortjournal = {The Astrophys. J.}, title = {The evolution of hypervelocity supernova survivors and the outcomes of interacting double white dwarf binaries}, volume = {982}, year = {2025}, }
• (2025). Baryon acoustic oscillations analyses with density-split statistics. ApJ, 982(1), 5. (www)

  @article{ , abstract = {Accurate modeling for the evolution of the baryon acoustic oscillation (BAO) is essential for using it as a standard ruler to probe cosmology. We explore the nonlinearity of the BAO in different environments using the density-split statistics and compare them to the case of the conventional two-point correlation function (2PCF). We detect density-dependent shifts for the position of the BAO with respect to its linear version using halos from N -body simulations. Around low/high-densities, the scale of the BAO expands/contracts due to nonlinear peculiar velocities. As the simulation evolves from redshift 1 to 0, the difference in the magnitude of the shifts between high- and low-dense regions increases from the subpercent to the percent level. The width of the BAO around high density regions increases as the universe evolves, similar to the known broadening of the BAO in the 2PCF due to nonlinear evolution. In contrast, the width is smaller and stable for low density regions. We discuss possible implications for the reconstructions of the BAO in light of our results.}, archive = {J_ApJ}, author = {Tengpeng Xu and Yan-Chuan Cai and Yun Chen and Mark Neyrinck and Liang Gao and Qiao Wang}, doi = {10.3847/1538-4357/adb4f0}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {5}, shortjournal = {The Astrophys. J.}, title = {Baryon acoustic oscillations analyses with density-split statistics}, volume = {982}, year = {2025}, }
• (2025). Propagation of waves in weakly ionized two-fluid plasmas. i. small-amplitude alfvénic waves. ApJ, 982(1), 4. (www)

  @article{ , abstract = {The large abundance of electrically neutral particles has a remarkable impact on the dynamics of many astrophysical plasmas. Here, we use a two-fluid model that includes charge-neutral elastic collisions and Hall's current to study the propagation of magnetohydrodynamic (MHD) waves in weakly ionized plasmas. We derive the dispersion relation for small-amplitude incompressible transverse waves propagating along the background magnetic field. Then, we focus on the polarization relations fulfilled by the eigenmodes and their corresponding ratios of magnetic to kinetic energies, and we study their dependence on the relations between the oscillation, collision, and cyclotron frequencies. For low wave frequencies, the two components of the plasma are strongly coupled, the damping due to the charge-neutral interaction is weak, and the effect of Hall's term is negligible. However, as the wave frequency increases, phase shifts between the velocity of charges, the velocity of neutrals, and the magnetic field appear, leading to enhanced damping. The effect of collisions on the propagation of waves strongly depends on their polarization state, with the left-handed circularly polarized ion-cyclotron modes being more efficiently damped than the linearly polarized Alfvén waves and the right-handed circularly polarized whistler modes. Moreover, the equipartition relation between the magnetic energy and the kinetic energy of Alfvén waves does not hold in general when the collisional interaction and Hall's current are taken into account, with the magnetic energy usually dominating over the kinetic energy. This theoretical result extends previous findings from observational and numerical works about turbulence in astrophysical scenarios.}, archive = {J_ApJ}, author = {David Martínez-Gómez}, doi = {10.3847/1538-4357/adb713}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {4}, shortjournal = {The Astrophys. J.}, title = {Propagation of waves in weakly ionized two-fluid plasmas. i. small-amplitude alfvénic waves}, volume = {982}, year = {2025}, }
• (2025). Using lithium and beryllium to study structure and evolution of rotating stars. ApJ, 982(1), 3. (www)

  @article{ , abstract = {The chemical composition of the Sun is still a highly controversial issue. No solar model has yet been able to simultaneously reproduce the solar lithium and beryllium abundances, along with helioseismic results, including the rotation profile. Lithium and beryllium are fragile elements that are highly sensitive to the physical conditions, as well as to transport and mixing processes within and below the convective zone (CZ). Uncovering the transport mechanisms responsible for the depletion of Li and Be in the Sun is crucial for using them as tools to understand stellar interiors and the associated transport and mixing processes. We constructed rotating solar models based on Magg's abundance scale, incorporating the effects of convective overshoot and magnetic fields. The rotating model exhibits superior sound speed and density profile and successfully reproduces the observed ratios r 02 and r 13 . It also matches the seismically inferred CZ depth, surface helium abundance, and rotation profile, as well as the detected Li and Be abundances and neutrino fluxes within 1 σ . The depletion of Li is dominated by convective overshoot and rotational mixing, while Be depletion is primarily driven by gravitational settling and rotational mixing. The presence of the tachocline accelerates Li depletion but slows down Be depletion. These distinct depletion mechanisms result in the surface abundances of Li and Be evolving differently over time.}, archive = {J_ApJ}, author = {Wuming Yang and Haibo Yuan and Yaqian Wu and Shaolan Bi and Zhijia Tian}, doi = {10.3847/1538-4357/adb730}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {3}, shortjournal = {The Astrophys. J.}, title = {Using lithium and beryllium to study structure and evolution of rotating stars}, volume = {982}, year = {2025}, }
• (2025). Analytical insights into inaccurate normal vector determination by minimum variance analysis of magnetic fields. ApJ, 982(1), 2. (www)

  @article{ , abstract = {It has been widely recognized that the minimum variance analysis of magnetic fields (MVAB) often fails to accurately predict the direction normal to a discontinuity or current sheet, compared with multiple-spacecraft methods. However, there is a lack of analytical proof to support this claim. In this paper, the accuracy of MVAB is tested using an analytical tangential and rotational discontinuity, where the exact normal is known. To evaluate the performance of MVAB, random fluctuations generated from a normal distribution, with varying magnitudes of variance ( {\sigma }^{2} ), are imposed on the {B}_{x} component. Results show that the MVAB normal is misaligned with the exact normal when {\sigma }^{2} is comparable to or larger than {\lambda }_{2}^{* } . Here, {\lambda }_{2}^{* } is the eigenvalue of the intermediate variance direction at {\sigma }^{2} = 0. To achieve good accuracy, it is required that {\lambda }_{2}/{\lambda }_{3} > 4.0, {\lambda }_{{Nc}0}/{\lambda }_{2} < 0.3, and {\lambda }_{{Ncp}}/{\lambda }_{2}\,\lt \, 0.3, where {\lambda }_{2} and {\lambda }_{3} are the eigenvalues of the intermediate and minimum variance directions, and {\lambda }_{{Nc}0} and {\lambda }_{{Ncp}} are the variances of the magnetic field components along the normals, predicted from the MVAB with the constraint \left\langle {B}_{n}\right\rangle = 0 and the cross-product method, respectively, within the MVAB interval. Notably, {\lambda }_{{Nc}0} and {\lambda }_{{Ncp}} closely match the designated {\sigma }^{2} . These two variance ratios, {\lambda }_{{Nc}0}/{\lambda }_{2} and {\lambda }_{{Ncp}}/{\lambda }_{2} , are introduced for the first time as measures to assess the accuracy of MVAB. Two event studies are presented: one demonstrates an accurate MVAB normal, while the other shows an unreliable one. The accuracy of MVAB follows the criteria for the three variance ratios.}, archive = {J_ApJ}, author = {Wai-Leong Teh}, doi = {10.3847/1538-4357/adb847}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {2}, shortjournal = {The Astrophys. J.}, title = {Analytical insights into inaccurate normal vector determination by minimum variance analysis of magnetic fields}, volume = {982}, year = {2025}, }
• (2025). An unexplained origin for the unusual globular cluster system in the ultradiffuse galaxy FCC 224. ApJ, 982(1), 1. (www)

  @article{ , abstract = {We study the quiescent ultradiffuse galaxy FCC 224 in the Fornax cluster using Hubble Space Telescope (HST) imaging, motivated by peculiar properties of its globular cluster (GC) system revealed in shallower imaging. The surface brightness fluctuation distance of FCC 224 measured from HST is 18.6 ± 2.7 Mpc, consistent with the Fornax cluster distance. We use Prospector to infer the stellar population from a combination of multiwavelength photometry (HST, ground-based, Wide-field Infrared Survey Explorer) and Keck Cosmic Web Imager spectroscopy. The galaxy has a mass-weighted age of ∼10 Gyr, metallicity [M/H] of ∼−1.25 dex, and a very short formation e -folding time of τ ∼ 0.3 Gyr. Its 12 candidate GCs exhibit highly homogeneous g 475 − I 814 colors, merely 0.04 mag bluer than the diffuse starlight, which supports a single-burst formation scenario for this galaxy. We confirm a top-heavy GC luminosity function, similar to the two dark matter deficient galaxies NGC 1052-DF2 and DF4. However, FCC 224 differs from those galaxies with relatively small GC sizes of ∼3 pc (∼35% smaller than typical for other dwarfs), and with radial mass segregation in its GC system. We are not yet able to identify a formation scenario to explain all of the GC properties in FCC 224. Follow-up measurements of the dark matter content in FCC 224 will be crucial because of the mix of similarities and differences among FCC 224, DF2, and DF4.}, archive = {J_ApJ}, author = {Yimeng Tang and Aaron J. Romanowsky and Jonah S. Gannon and Steven R. Janssens and Jean P. Brodie and Kevin A. Bundy and Maria Luisa Buzzo and Enrique A. Cabrera and Shany Danieli and Anna Ferré-Mateu and Duncan A. Forbes and Pieter G. van Dokkum}, doi = {10.3847/1538-4357/adae11}, journal = {The Astrophysical Journal}, month = {3}, number = {1}, pages = {1}, shortjournal = {The Astrophys. J.}, title = {An unexplained origin for the unusual globular cluster system in the ultradiffuse galaxy FCC 224}, volume = {982}, year = {2025}, }
• (2025). The unexpected lack of asymmetry in the horizon-scale image of sagittarius a*. ApJ, 981(2), 209. (www)

  @article{ , abstract = {The ring-like images of the two supermassive black holes captured by the Event Horizon Telescope (EHT) provide powerful probes of the physics of accretion flows at horizon scales. Specifically, the brightness asymmetry in the images carries information about the angular velocity profile of the inner accretion flow and the inclination of the observer, owing to the Doppler boosts photons experience at their site of emission. In this paper, we develop a method for quantifying the brightness asymmetry of black hole images in the Fourier domain, which can be measured directly from interferometric data. We apply this method to current EHT data and find that the image of Sagittarius A* (Sgr A*) has an unusually low degree of asymmetry that is even lower than that inferred for M87. We then use a covariant semianalytic model to obtain constraints on the inclinations and velocity profiles of the inner accretion flow for Sgr A*. We find that the lack of significant brightness asymmetry forces the observer inclination to uncomfortably small values (6°–10 ∘ ), if the plasma velocity follows Keplerian profiles. Alternatively, larger inclination angles can be accommodated if the plasma velocities are significantly sub-Keplerian and the black hole is not spinning rapidly.}, archive = {J_ApJ}, author = {J. Cole Faggert and Feryal Özel and Dimitrios Psaltis}, doi = {10.3847/1538-4357/ad9689}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {209}, shortjournal = {The Astrophys. J.}, title = {The unexpected lack of asymmetry in the horizon-scale image of sagittarius a*}, volume = {981}, year = {2025}, }
• (2025). Looking at the distant universe with the MeerKAT array: The h i mass function in the local universe. ApJ, 981(2), 208. (www)

  @article{ , abstract = {We present measurements of the neutral atomic hydrogen (H i ) mass function (H i MF) and cosmic H i density (Ω H I ) at 0 ≤ z ≤ 0.088 from the Looking at the Distant Universe with MeerKAT Array (LADUMA) survey. Using LADUMA Data Release 1 (DR1), we analyze the H i MF via a new "recovery matrix" method that we benchmark against a more traditional modified maximum likelihood (MML) method. Our analysis, which implements a forward modeling approach, corrects for survey incompleteness and uses extensive synthetic source injections to ensure robust estimates of the H i MF parameters and their associated uncertainties. This new method tracks the recovery of sources in mass bins different from those in which they were injected and incorporates a Poisson likelihood in the forward modeling process, allowing it to correctly handle uncertainties in bins with few or no detections. The application of our analysis to a high-purity subsample of the LADUMA DR1 spectral line catalog in turn mitigates any possible biases that could result from the inconsistent treatment of synthetic and real sources. For the surveyed redshift range, the recovered Schechter function normalization, low-mass slope, and "knee" mass are {\phi }_{* }=3.5{6}_{-1.92}^{+0.97}\times 1{0}^{-3} Mpc −3 dex −1 , \alpha =-1.1{8}_{-0.19}^{+0.08} , and \mathrm{log}({M}_{* }/{M}_{\odot })=10.0{1}_{-0.12}^{+0.31} , respectively, which together imply a comoving cosmic H i density of {{\rm{\Omega }}}_{{\rm{H}}\,{\rm{I}}}=3.0{9}_{-0.47}^{+0.65}\times 1{0}^{-4} . Our results show consistency between recovery matrix and MML methods and with previous low-redshift studies, giving confidence that the cosmic volume probed by LADUMA, even at low redshifts, is not an outlier in terms of its H i content.}, archive = {J_ApJ}, author = {Amir Kazemi-Moridani and Andrew J. Baker and Marc Verheijen and Eric Gawiser and Sarah-Louise Blyth and Danail Obreschkow and Laurent Chemin and Jordan D. Collier and Kyle W. Cook and Jacinta Delhaize and Ed Elson and Bradley S. Frank and Marcin Glowacki and Kelley M. Hess and Benne W. Holwerda and Zackary L. Hutchens and Matt J. Jarvis and Melanie Kaasinen and Sphesihle Makhathini and Abhisek Mohapatra and Hengxing Pan and Anja C. Schröder and Leyya Stockenstroom and Mattia Vaccari and Tobias Westmeier and John F. Wu and Martin Zwaan}, doi = {10.3847/1538-4357/ad9f3f}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {208}, shortjournal = {The Astrophys. J.}, title = {Looking at the distant universe with the MeerKAT array: The h i mass function in the local universe}, volume = {981}, year = {2025}, }
• (2025). The young ages of 70 μm dark clumps inferred from carbon chain chemistry. ApJ, 981(2), 207. (www)

  @article{ , abstract = {The physical conditions of the earliest environment of high-mass star formation are currently poorly understood. To that end, we present observations of the carbon chain molecules HC 5 N, CCS, and HC 7 N in the 22–25 GHz band toward 12 high-mass 70 μ m dark clumps (SMDC) with the Karl G. Jansky Very Large Array. We detect HC 5 N and CCS toward 11 of these SMDC sources. We calculate column densities and abundances relative to H 2 for HC 5 N and CCS. We do not find any clear HC 7 N detections in the 11 sources individually, but by stacking the HC 7 N spectra, we do detect HC 7 N on average in these sources. We also calculate the ratio of the column densities of HC 5 N to HC 7 N using the stacked spectra of both species. We compare our measured abundances of HC 5 N and our measured ratio of HC 5 N to HC 7 N to the UMIST dark cloud chemistry models to constrain an age for the gas assuming a fixed volume density and temperature. The chemical models favor a chemical evolutionary age <1 Myr at densities of n (H 2 ) ≈ 2 × 10 4 cm −3 . The consistent carbon-chain detections and young model-derived ages support the conclusion that these 11 70 μ m dark clumps lack high-mass protostars because they are young and not because they are inefficient and incapable of high-mass star formation.}, archive = {J_ApJ}, author = {Kadin Worthen and Brian E. Svoboda and David S. Meier and Juergen Ott and Rachel Friesen and Jennifer Patience and Yancy Shirley}, doi = {10.3847/1538-4357/adabdd}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {207}, shortjournal = {The Astrophys. J.}, title = {The young ages of 70 μm dark clumps inferred from carbon chain chemistry}, volume = {981}, year = {2025}, }
• (2025). Global turbulent solar convection: A numerical path investigating key force balances in the context of the convective conundrum. ApJ, 981(2), 206. (www)

  @article{ , abstract = {Understanding solar turbulent convection and its influence on differential rotation has been a challenge over the past two decades. Current models often overestimate giant convection cells' amplitude, leading to an effective Rossby number (Ro) too large and a shift toward an antisolar rotation regime. This convective conundrum underscores the need for improved comprehension of solar convective dynamics. We propose a numerical experiment in the parameter space that controls Ro while increasing the Reynolds number (Re) and maintaining solar parameters. By controlling the Nusselt number (Nu), we limit the energy transport by convection while reducing viscous dissipation. This approach enabled us to construct a Sun-like rotating model (SBR97n035) with strong turbulence (Re ∼ 800) that exhibits prograde equatorial rotation and aligns with observational data from helioseismology. We compare this model with an antisolar rotating counterpart and provide an in-depth spectral analysis to investigate the changes in convective dynamics. We also find the appearance of vorticity rings near the poles, whose existence on the Sun could be probed in the future. The Sun-like model shows reduced buoyancy over the spectrum, as well as an extended quasi-geostrophic equilibrium toward smaller scales. This promotes a Coriolis–inertia (CI) balance rather than a Coriolis–inertia–Archimedes (CIA) balance, in order to favor the establishment of a prograde equator. The presence of convective columns in the bulk of the convection zone, with limited surface manifestations, also hints at such structures potentially occurring in the Sun.}, archive = {J_ApJ}, author = {Quentin Noraz and Allan Sacha Brun and Antoine Strugarek}, doi = {10.3847/1538-4357/adad59}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {206}, shortjournal = {The Astrophys. J.}, title = {Global turbulent solar convection: A numerical path investigating key force balances in the context of the convective conundrum}, volume = {981}, year = {2025}, }
• (2025). Discovery of a new phase-transient cyclotron line in a0535+26: Constraints on the accretion geometry. ApJ, 981(2), 205. (www)

  @article{ , abstract = {In 2020 November, A0535+26 underwent one of its brightest outbursts, reaching nearly 12 Crab in X-ray flux. Observed by Insight-HXMT, NuSTAR, NICER, and AstroSat, this event provided valuable insights into Be/X-ray binaries. The pulse profiles evolved significantly with luminosity, transitioning from pencil-beam to fan-beam geometries. A0535+26, known for its fundamental cyclotron line at ∼44 keV, became only the second source to exhibit a negative correlation between cyclotron line energy and flux at high luminosities, with a plateau phase preceding the transition from positive to negative correlation. We report the discovery of a phase-transient low-energy cyclotron line, detected in a narrow phase range (∼16%) across all seven NuSTAR observations during the rising, peak, and declining phases of the outburst. The new line exhibited dramatic variations with pulse phase and luminosity. We explain this behavior using an accretion geometry where the accretion column sweeps across the line of sight.}, archive = {J_ApJ}, author = {Ashwin Devaraj and Biswajit Paul and Varun Bhalerao and Dipanjan Mukherjee}, doi = {10.3847/1538-4357/adb0c2}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {205}, shortjournal = {The Astrophys. J.}, title = {Discovery of a new phase-transient cyclotron line in a0535+26: Constraints on the accretion geometry}, volume = {981}, year = {2025}, }
• (2025). Signatures of black hole spin and plasma acceleration in jet polarimetry. ApJ, 981(2), 204. (www)

  @article{ , abstract = {We study the polarization of black hole jets on scales of 10−10 3 GM / c 2 and show that large spatial swings in the polarization occur at three characteristic distances from the black hole: the radius where the counter-jet dims, the radius where the magnetic field becomes azimuthally dominated (the light cylinder), and the radius where the plasma reaches its terminal Lorentz factor. To demonstrate the existence of these swings, we derive a correspondence between axisymmetric magnetohydrodynamic outflows and their force-free limits, which allows us to analytically compute the plasma kinematics and magnetic field structure of collimated, general relativistic jets. We then use this method to ray trace polarized images of black hole jets with a wide range of physical parameters, focusing on roughly face-on jets like that of M87. We show that the location of the polarization swings is strongly tied to the location of the light cylinder and thus to the black hole's spin, illustrating a new method of measuring spin from polarized images of the jet. This signature of black hole spin should be observable by future interferometric arrays like the (Next Generation) Event Horizon Telescope, which will be able to resolve the polarized emission of the jet down to the near-horizon region at high dynamic range.}, archive = {J_ApJ}, author = {Z. Gelles and A. Chael and E. Quataert}, doi = {10.3847/1538-4357/adb1aa}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {204}, shortjournal = {The Astrophys. J.}, title = {Signatures of black hole spin and plasma acceleration in jet polarimetry}, volume = {981}, year = {2025}, }
• (2025). MAGICS. III. seeds sink swiftly: Nuclear star clusters dramatically accelerate seed black hole mergers. ApJ, 981(2), 203. (www)

  @article{ , abstract = {Merger rate predictions of massive black hole (MBH) seeds from large-scale cosmological simulations differ widely, with recent studies highlighting the challenge of low-mass MBH seeds failing to reach the galactic center, a phenomenon known as the seed sinking problem. In this work, we tackle this issue by integrating cosmological simulations and galaxy merger simulations from the MAGICS-I and MAGICS-II resimulation suites with high-resolution N -body simulations. Building on the findings of MAGICS-II, which showed that only MBH seeds embedded in stellar systems are able to sink to the center, we extend the investigation by incorporating nuclear star clusters (NSCs) into our models. Utilizing N -body resimulations with up to 10 7 particles, we demonstrate that interactions between NSCs and their surrounding galactic environment, particularly tidal forces triggered by cluster interactions, significantly accelerate the sinking of MBHs to the galactic center. This process leads to the formation of a hard binary in ≲500 Myr after the onset of a galaxy merger. Our results show that in eight out of 12 models, the high stellar density of the surrounding NSCs enhances MBH hardening, facilitating gravitational-wave mergers by redshift z = 4. We conclude that at z > 4, dense NSCs serve as the dominant channel for MBH seed mergers, producing a merger rate of 0.3–0.6 yr −1 at z = 4, which is approximately 300–600 times higher than in non-NSC environments. In contrast, in environments without NSCs, surrounding dark matter plays a more significant role in loss-cone scattering.}, archive = {J_ApJ}, author = {Diptajyoti Mukherjee and Yihao Zhou and Nianyi Chen and Ugo Niccolò Di Carlo and Tiziana Di Matteo}, doi = {10.3847/1538-4357/adb1b0}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {203}, shortjournal = {The Astrophys. J.}, title = {MAGICS. III. seeds sink swiftly: Nuclear star clusters dramatically accelerate seed black hole mergers}, volume = {981}, year = {2025}, }
• (2025). BASS. XLVII. 22 GHz radio atlas of swift-BAT selected AGN. ApJ, 981(2), 202. (www)

  @article{ , abstract = {We present the third phase of the largest high-frequency, high-resolution imaging survey of 231 nearby, hard X-ray selected active galactic nuclei (AGNs), with a very high 98% ± 1% detection fraction. This survey presents VLA 22 GHz radio observations with 1 '' spatial resolution covering over 6 orders of magnitude in radio luminosity in nearby AGNs that span ∼4 orders of magnitude in black hole mass and X-ray luminosity. We identify three different radio morphologies: 44% ± 3% (102/231) are compact or unresolved, 46% ± 3% (106/231) show an extended structure (star formation, possible one-sided jets, etc.), and 8% ± 2% (19/231) have a biconical or two-sided jet-like morphology. The remaining 2% ± 1% (4/231) sources are nondetections. The radio-to-X-ray luminosity ratios of the Swift-BAT AGNs in our sample ( L R / L 14−195keV ∼ 10 −5.5 and L R / L 2−10keV ∼ 10 −5 with a scatter of ∼0.5 dex) are similar to that of coronally active stars ( L R / L X ∼ 10 −5 ). For most targets, extended emission in radio-quiet objects is broadly consistent with the expectation for star formation from previous far-infrared observations once the contribution from the radio core has been subtracted. Our sample represents nearby analogs of distant AGNs at the peak of black hole growth, and thus the high detection fraction in our work has important implications for future high frequency AGN radio surveys with the next generation Very Large Array or Square Kilometre Array, both of which should detect large fractions of more distant AGNs.}, archive = {J_ApJ}, author = {Macon Magno and Krista L. Smith and O. Ivy Wong and Richard Mushotzky and Stuart Vogel and Michael J. Koss and Claudio Ricci and Kyuseok Oh and Chin-Shin Chang and Loreto Barcos-Muñoz and Franz E. Bauer and Alessandro Peca and Darshan Kakkad and Turgay Caglar and Benny Trakhtenbrot and Fiona Harrison and Daniel Stern and C. Megan Urry and Merry Powell}, doi = {10.3847/1538-4357/adb1e7}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {202}, shortjournal = {The Astrophys. J.}, title = {BASS. XLVII. 22 GHz radio atlas of swift-BAT selected AGN}, volume = {981}, year = {2025}, }
• (2025). Correlated molybdenum, ruthenium, and barium isotope anomalies in presolar silicon carbide grains. ApJ, 981(2), 201. (www)

  @article{ , abstract = {We have analyzed molybdenum, ruthenium, and barium isotopes simultaneously in 55 individual presolar silicon carbide (SiC) grains from the Murchison CM2 meteorite using the Chicago Instrument for Laser Ionization (or CHILI). Most grains show clear s -process signatures, which are strongly correlated for molybdenum and ruthenium. For all three elements, we provide estimates for s -process contributions from low-mass AGB stars with unprecedented precision. Variations in s -process production observed for some nuclides reflect a strong dependence on physical properties, neutron density, temperature, and timing, affecting various s -process branch points. Significant contamination can be excluded for a majority of grains. Instead, distributions along mixing lines in three-isotope diagrams reflect mixing between initial parent star material and matter synthesized in the star. The results suggest that the ratios between p - and r -process isotopes of molybdenum, ruthenium, and barium in presolar SiC from many parent stars are the same as the ones inferred for the solar system. This indicates that the products of these processes were well mixed by the time the molecular cloud collapsed to form the stars that eventually grew the SiC grains, and that this mixture did not change between formation of the precursor stars and formation of the Sun.}, archive = {J_ApJ}, author = {Thomas Stephan and Peter Hoppe and Andrew M. Davis and Julie M. Korsmeyer and Andrew Regula and Hannah E. Richards}, doi = {10.3847/1538-4357/adb308}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {201}, shortjournal = {The Astrophys. J.}, title = {Correlated molybdenum, ruthenium, and barium isotope anomalies in presolar silicon carbide grains}, volume = {981}, year = {2025}, }
• (2025). The impacts of magnetogram projection effects on solar flare forecasting. ApJ, 981(2), 200. (www)

  @article{ , abstract = {This work explores the impacts of magnetogram projection effects on machine-learning-based solar flare forecasting models. Utilizing a methodology proposed by D. A. Falconer et al., we correct for projection effects present in Georgia State University's Space Weather Analytics for Solar Flares benchmark data set. We then train and test a support vector machine classifier on the corrected and uncorrected data, comparing differences in performance. Additionally, we provide insight into several other methodologies that mitigate projection effects, such as stacking ensemble classifiers and active region location-informed models. Our analysis shows that data corrections slightly increase both the true-positive (correctly predicted flaring samples) and false-positive (nonflaring samples predicted as flaring) prediction rates, averaging a few percent. Similarly, changes in performance metrics are minimal for the stacking ensemble and location-based model. This suggests that a more complicated correction methodology may be needed to see improvements. It may also indicate inherent limitations when using magnetogram data for flare forecasting.}, archive = {J_ApJ}, author = {Griffin T. Goodwin and Viacheslav M. Sadykov and Petrus C. Martens}, doi = {10.3847/1538-4357/adb4f6}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {200}, shortjournal = {The Astrophys. J.}, title = {The impacts of magnetogram projection effects on solar flare forecasting}, volume = {981}, year = {2025}, }
• (2025). Candidate intermediate-mass black hole discovered in an extremely young low-metallicity cluster in the tadpole galaxy KUG 1138+327. ApJ, 981(2), 199. (www)

  @article{ , abstract = {We explore what unusual products a starburst of about 6% solar metallicity and a mean estimated age of ∼5 × 10 5 yr can produce in KUG 1138+327 at a distance of 24.5 Mpc. Chandra X-ray observations show a dominant point-like source with an average 0.3–10 keV luminosity of 10 40.3 erg s −1 and variability by a factor of ∼2 over months. This extreme ultraluminous X-ray source (ULX) is apparently associated with the young central cluster. A multicolor disk modeling of the X-ray spectrum of the source suggests a standard accretion around a black hole. It also has a morphologically elongated nonthermal radio continuum counterpart on the scale of ∼200 pc, probably the longest detected from such a source. The radio, optical, and X-ray findings suggest that it could well be an intermediate-mass black hole undergoing sub-Eddington accretion from a massive star companion. Accounting for the presence of the ULX and the prominent emission lines He II λ 4658 and [Ar IV ] λ 4711 while lacking Wolf–Rayet spectral features, we estimate the true age of the starburst to be about 2–4 Myr. Only with such a moderate age can the starburst host this extraordinary ULX, probably triggered by a recent influx of extremely low-metallicity gas. This study demonstrates the potential of multiwavelength studies of low-metallicity starbursts to provide insights into what may commonly occur in high-redshift galaxies.}, archive = {J_ApJ}, author = {Q. Daniel Wang and Juergen Ott}, doi = {10.3847/1538-4357/adb4f8}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {199}, shortjournal = {The Astrophys. J.}, title = {Candidate intermediate-mass black hole discovered in an extremely young low-metallicity cluster in the tadpole galaxy KUG 1138+327}, volume = {981}, year = {2025}, }
• (2025). On the light curves of disk and bulge novae. ApJ, 981(2), 198. (www)

  @article{ , abstract = {We examine the light curves of a sample of novae, classifying them into single-peaked and multiple-peaked morphologies. Using accurate distances from Gaia, we determine the spatial distribution of these novae by computing their heights, Z , above the Galactic plane. We show that novae exhibiting a single peak in their light curves tend to concentrate near the Galactic plane, while those displaying multiple peaks are more homogeneously distributed, reaching heights up to 1000 pc above the plane. A K-S test rejects the null hypothesis that the two distributions originate from the same population at a significance level corresponding to 4.2 σ .}, archive = {J_ApJ}, author = {Asaf Cohen and Dafne Guetta and Yael Hillman and Massimo Della Valle and Luca Izzo and Volker Perdelwitz and Mario Livio}, doi = {10.3847/1538-4357/adb628}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {198}, shortjournal = {The Astrophys. J.}, title = {On the light curves of disk and bulge novae}, volume = {981}, year = {2025}, }
• (2025). On the feasibility of deriving pseudo-redshifts of gamma-ray bursts from two phenomenological correlations. ApJ, 981(2), 197. (www)

  @article{ , abstract = {Accurate knowledge of gamma-ray burst (GRB) redshifts is essential for studying their intrinsic properties and exploring their potential applications in cosmology. Currently, only a small fraction of GRBs have independent redshift measurements, primarily due to the need for rapid follow-up optical/IR spectroscopic observations. For this reason, many have utilized phenomenological correlations to derive pseudo-redshifts of GRBs with no redshift measurement. In this work, we explore the feasibility of analytically deriving pseudo-redshifts directly from the Amati and Yonetoku relations. We simulate populations of GRBs that: (i) fall perfectly on the phenomenological correlation track; and (ii) include intrinsic-scatter matching observations. Our findings indicate that in the case of the Amati relation, the mathematical formulation is ill-behaved, in that it yields two solutions within a reasonable redshift range z ∈ [0.1, 10]. When realistic scatter is included, it may result in no solution, or the redshift error range is excessively large. In the case of the Yonetoku relation, while it can result in a unique solution in most cases, the large systematic errors of the redshift call for attention, especially when attempting to use pseudo-redshifts to study GRB population properties.}, archive = {J_ApJ}, author = {Emre S. Yorgancioglu and Yun-Fei Du and Shu-Xu Yi and Rahim Moradi and Hua Feng and Shuang-Nan Zhang}, doi = {10.3847/1538-4357/adb712}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {197}, shortjournal = {The Astrophys. J.}, title = {On the feasibility of deriving pseudo-redshifts of gamma-ray bursts from two phenomenological correlations}, volume = {981}, year = {2025}, }
• (2025). Shear particle acceleration in structured gamma-ray burst jets. II. viewing angle effect on the prompt emission and application to GRB 170817A. ApJ, 981(2), 196. (www)

  @article{ , abstract = {Multimessenger observations suggest that the gamma-ray burst on 2017 August 17 (GRB 170817A) resulted from off-axial observations of its structured jet, which consists of a narrow ultrarelativistic jet core surrounded by a wide mild-relativistic cocoon. In a serious paper, we explore the emission of shear-accelerated electrons in the mixed jet-cocoon region in a series of papers. This paper focuses on the viewing angle effect for a structured jet by considering the emission from the shear-accelerated electrons. It is found that the observed synchrotron (Syn) emission peaks at the infrared band and the Syn self-Compton emission peaks at the band of hundreds of keV. They are not sensitive to the viewing angle. In the off-axis observations scenario, the prompt emission spectrum is dominated by the emission of the shear-accelerated electrons. The prompt gamma-ray spectrum of GRB 170817A can be well explained with our model by setting the velocity of the inner edge of the cocoon region as 0.9 c , the magnetic field strength as 21 G, the injected initial electron Lorentz factor as 10 3 , and the viewing angle as 0.44 rad. We argue that the joint observations in the infrared/optical and X-ray bands are critical to verify our model.}, archive = {J_ApJ}, author = {Zi-Qi Wang and Xiao-Li Huang and En-Wei Liang}, doi = {10.3847/1538-4357/adb722}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {196}, shortjournal = {The Astrophys. J.}, title = {Shear particle acceleration in structured gamma-ray burst jets. II. viewing angle effect on the prompt emission and application to GRB 170817A}, volume = {981}, year = {2025}, }
• (2025). Hydrostatic equilibrium constraints in X-COP galaxy clusters: Testing hyperconical modified gravity in hot-gas-dominated regions. ApJ, 981(2), 195. (www)

  @article{ , abstract = {Modified Newtonian dynamics (MOND) was originally proposed to model galaxy rotation curves without dark matter. However, MOND presents difficulties in explaining the radial acceleration relation observed in galaxy clusters, and moreover, it does not completely eliminate the need for dark matter, since it requires using nonluminous particles (e.g., cold molecular gas or dust, or neutrinos) to explain the observed hydrostatic equilibrium of the hot gas. Hyperconical modified gravity (HMG) offers a relativistic framework that recovers the success of MOND in galaxy rotation curves as a natural particular case, and it could potentially reconcile the previously described discrepancies without invoking any type of dark matter. This paper analyzes the performance of the HMG model for hydrostatic equilibrium in 12 XMM Cluster Outskirts Project galaxy clusters, with a special focus on 5 objects with available complete stellar mass information: A1795, A2029, A2142, A2319, and A644. Specifically, we used high-resolution X-ray data with which gas density and mass profiles were previously derived to constrain modified gravity models. Our results show that the hydrostatic equilibrium of analyzed cluster gas is more naturally adjusted to the HMG model beyond 1 Mpc, reducing the need to fit parameters, but further research is required to expand to more spatial scales.}, archive = {J_ApJ}, author = {Robert Monjo}, doi = {10.3847/1538-4357/adb723}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {195}, shortjournal = {The Astrophys. J.}, title = {Hydrostatic equilibrium constraints in X-COP galaxy clusters: Testing hyperconical modified gravity in hot-gas-dominated regions}, volume = {981}, year = {2025}, }
• (2025). Measuring the interstellar medium content of nearby, luminous, type 1 and type 2 QSOs through CO and [C ii]. ApJ, 981(2), 194. (www)

  @article{ , abstract = {We present observations of CO(1–0) and CO(2–1) lines from the Institut de radioastronomie millimétrique 30 m telescope toward 20 nearby, optically luminous type 2 quasars (QSO2s) and observations of the [C ii ] 158 μ m line from the Stratospheric Observatory for Infrared Astronomy for five QSO2s in the CO sample and five type 1 quasars (QSO1s). In the traditional evolutionary scenario explaining different types of QSOs, obscured QSO2s emerge from gas-rich mergers observed as luminous infrared galaxies (LIRGs) and then turn into unobscured QSO1s as the black holes clear out the obscuring material in a blowout phase. We test the validity of this theoretical prediction by comparing the gas fractions and star formation efficiencies among LIRGs and QSOs. We find that CO luminosity, CO-derived gas masses, and gas fractions in QSO1s are consistent with those estimated for QSO2s, while LIRGs exhibit a closer resemblance to QSO2s in terms of CO-derived gas masses and gas fractions. Comparisons between [C ii ] luminosity and star formation tracers such as the CO and infrared luminosity imply additional sources of [C ii ] emission in QSO1s likely tracing neutral atomic or ionized gas with the caveat of a small sample size. All three types of galaxies have statistically indistinguishable distributions of star formation efficiency. Our results are consistent with part of the evolutionary scenario where nearby QSO2s could emerge from LIRGs, but they may not be the precursors of nearby QSO1s.}, archive = {J_ApJ}, author = {Yuanze Luo and A. O. Petric and R. M. J. Janssen and D. Fadda and N. Flagey and A. Omont and A. M. Jacob and K. Rowlands and K. Alatalo and N. Billot and T. Heckman and B. Husemann and D. Kakkad and M. Lacy and J. Marshall and R. Minchin and R. Minsley and N. Nesvadba and J. A. Otter and P. Patil and T. Urrutia}, doi = {10.3847/1538-4357/adb13b}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {194}, shortjournal = {The Astrophys. J.}, title = {Measuring the interstellar medium content of nearby, luminous, type 1 and type 2 QSOs through CO and [C ii]}, volume = {981}, year = {2025}, }
• (2025). Gas-phase oxygenation and sulfurization processes of fullerene cations. ApJ, 981(2), 193. (www)

  @article{ , abstract = {Atomic oxygen and sulfur are known to efficiently react with fullerenes and may thus form a long list of oxygenated and sulfurated fullerene species in the interstellar medium (ISM). In this work, the gas-phase collision reactions between fullerene (C 60 and C 54/56/58 ) cations and 18 O or S atoms are investigated. Oxygenated and sulfurated fullerene cations ([C 60 18 O 1−6 ] + , [C 54/56/58 18 O 1−3 ] + and [C 60 S 1−4 ] + , [C 54/56/58 S 1−4 ] + ) are efficiently formed. Under laser irradiation, O-atom and CO-unit loss channels are identified in the photodeoxygenation processes; [C 60 O] + only has an O-atom loss channel. Smaller fullerene cations can be produced through sequential steps, and species with repeatedly lost CO units, i.e., fullerenes containing odd carbon numbers (e.g., 55 or 57 C atoms), can be produced in the photodeoxygenation processes of oxygenated fullerene cations. A S-atom loss channel and no CS-unit loss channel are identified in the photodesulfurization processes. Through theoretical calculations, the structures of oxygenated and sulfurated fullerene cations (e.g., [C 60 18 O] + and [C 60 S] + ) and the bonding energies for the formation reaction pathways are investigated, together with their IR spectra. The exothermic energy for each reaction pathway is relatively high. Consequently, the oxygenation or sulfurization states and forms of fullerene compounds are intricate and complex. In addition, different types of oxygenation and sulfurization bonds are obtained with their evolution. Importantly, we infer that the photodeoxygenation of mono-oxygenated fullerene species or the photodesulfurization of sulfurated fullerene species is not involved in the top-down chemical evolution routes of buckminsterfullerene (C 60 ) in the ISM.}, archive = {J_ApJ}, author = {Nian Zhao and Xiaoyi Hu and Yanan Ge and Congcong Zhang and Aigen Li and Junfeng Zhen and Xuejuan Yang}, doi = {10.3847/1538-4357/adb42d}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {193}, shortjournal = {The Astrophys. J.}, title = {Gas-phase oxygenation and sulfurization processes of fullerene cations}, volume = {981}, year = {2025}, }
• (2025). Limits on the low-energy electron antineutrino flux from the brightest gamma-ray burst of all time. ApJ, 981(2), 192. (www)

  @article{ , abstract = {The electron antineutrino flux limits are presented for the brightest gamma-ray burst (GRB) of all time, GRB221009A, over a range of 1.8–200 MeV using the Kamioka Liquid Scintillator Antineutrino Detector. Using multiple time windows ranging from minutes to days surrounding the event to search for electron antineutrinos coincident with the GRB, we set an upper limit on the flux under the assumption of several power-law neutrino source spectra, with power-law indices ranging from 1.5 to 3 in steps of 0.5. No excess was observed in any time windows ranging from seconds to days around the event trigger time T 0 . For a power-law index of 2 and a time window of T 0 ±  500 s, a flux upper limit of 2.34 × 10 9 cm −2 was calculated. The limits are compared to the results presented by IceCube.}, archive = {J_ApJ}, author = {S. Abe and T. Araki and S. Chauhan and K. Chiba and T. Eda and M. Eizuka and Y. Funahashi and A. Furuto and A. Gando and Y. Gando and S. Goto and T. Hachiya and K. Hata and K. Ichimura and H. Ikeda and K. Inoue and K. Ishidoshiro and Y. Kamei and N. Kawada and Y. Kishimoto and M. Koga and A. Marthe and Y. Matsumoto and T. Mitsui and H. Miyake and D. Morita and R. Nakajima and K. Nakamura and R. Nakamura and J. Nakane and T. Ono and H. Ozaki and K. Saito and T. Sakai and I. Shimizu and J. Shirai and K. Shiraishi and A. Suzuki and K. Tachibana and K. Tamae and H. Watanabe and K. Watanabe and S. Kurosawa and Y. Urano and S. Yoshida and S. Umehara and K. Fushimi and K. Kotera and B. E. Berger and B. K. Fujikawa and J. G. Learned and J. Maricic and Z. Fu and S. Ghosh and J. Smolsky and L. A. Winslow and Y. Efremenko and H. J. Karwowski and D. M. Markoff and W. Tornow and S. Dell’Oro and T. O’Donnell and J. A. Detwiler and S. Enomoto and M. P. Decowski and K. M. Weerman and C. Grant and Ö. Penek and H. Song and A. Li and S. N. Axani and M. Garcia and M. Sarfraz and The KamLAND Collaboration}, doi = {10.3847/1538-4357/ad9c36}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {192}, shortjournal = {The Astrophys. J.}, title = {Limits on the low-energy electron antineutrino flux from the brightest gamma-ray burst of all time}, volume = {981}, year = {2025}, }
• (2025). UNCOVER: 404 Error—Models not found for the triply imaged little red dot a2744-QSO1*. ApJ, 981(2), 191. (www)

  @article{ , abstract = {JWST has revealed an abundance of compact, red objects at z ≈ 5–8 dubbed "little red dots" (LRDs), whose SEDs display a faint blue UV continuum followed by a steep rise in the optical. Despite extensive study of their characteristic V-shaped SEDs, the nature of LRDs remains unknown. We present a new analysis of the NIRSpec/PRISM spectrum of A2744-QSO1, a triply imaged LRD at z = 7.04 from the UNCOVER survey. The spectrum shows a strong Balmer break and broad Balmer emission lines, both of which are difficult to explain with models invoking exclusively AGN or stellar contributions. Our fiducial model decomposes the spectrum into a post-starburst galaxy dominating the UV-optical continuum and a reddened AGN being subdominant at all wavelengths and contributing at a level of ∼20%. However, this model infers a stellar mass of M ⋆ ≈ 4 × 10 9 M ⊙ within a radius of r e < 30 pc, driving its central density to the highest among observations to date. This high central density could be explained if A2744-QSO1 is the early-forming core of a modern-day massive elliptical galaxy that later puffed up via the inside-out growth channel. The models also necessitate an unusually steep dust extinction law to preserve the strong break strength, though this steepness may be explained by a deficit of large dust grains. It is also probable that these challenges reflect our ignorance of A2744-QSO1's true nature. Future variability and reverberation mapping studies could help disentangle the galaxy and AGN contribution to the continuum, and deeper redder observations could also unveil the dust properties in LRDs.}, archive = {J_ApJ}, author = {Yilun Ma and Jenny E. Greene and David J. Setton and Marta Volonteri and Joel Leja and Bingjie Wang and Rachel Bezanson and Gabriel Brammer and Sam E. Cutler and Pratika Dayal and Pieter van Dokkum and Lukas J. Furtak and Karl Glazebrook and Andy D. Goulding and Anna de Graaff and Vasily Kokorev and Ivo Labbe and Richard Pan and Sedona H. Price and John R. Weaver and Christina C. Williams and Katherine E. Whitaker and Adi Zitrin}, doi = {10.3847/1538-4357/ada613}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {191}, shortjournal = {The Astrophys. J.}, title = {UNCOVER: 404 Error—Models not found for the triply imaged little red dot a2744-QSO1*}, volume = {981}, year = {2025}, }
• (2025). Cosmic-ray-driven thermal modes in partially ionized viscous plasma with hall current. ApJ, 981(2), 190. (www)

  @article{ , abstract = {This research investigates the dynamics of cosmic-ray-driven thermal modes within a partially ionized plasma permeated by a magnetic field. A two-fluid model is adopted to capture the intricate physics arising from the presence of neutral dynamics. The ion–cosmic fluid is described using a nonideal magnetohydrodynamic framework, incorporating ion and neutral viscosities, the Hall current, and ion–neutral collisions. Neutral dynamics are characterized by neutral viscosity, pressure, and collisional interactions. The derived general dispersion relation reveals two dominant modes: a collisional neutral thermal viscous mode and a Hall-modified cosmic magnetothermal viscous mode. The domains of instability for the neutral thermal viscous mode are determined, while the stability of the ion–cosmic thermal viscous mode is assessed using the Routh–Hurwitz criterion, yielding critical lengths for isochoric, isobaric, and isentropic modes. In the collisional regime, a seventh-order dispersion relation is derived and analyzed numerically. Next, the second dominant mode of the general dispersion relation is further analyzed in both transverse and longitudinal directions relative to the magnetic field. In the transverse direction, a seventh-order collisional cosmic magnetothermal viscous mode is obtained, influenced by ion and neutral viscosities, the diffusion coefficient, collisions, and the cosmic and ion acoustic speeds. This mode is further investigated analytically and numerically. Numerical estimates demonstrate that the diffusion coefficient and cosmic pressure enhance the growth rate of thermal modes. The critical wavelength of the magnetothermal cosmic mode is calculated. In the longitudinal direction, the obtained modes exhibit no substantial cosmic influence, but instead represent Hall-modified collisional Alfvén waves.}, archive = {J_ApJ}, author = {Prerana Sharma and Shweta Jain}, doi = {10.3847/1538-4357/ada9e8}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {190}, shortjournal = {The Astrophys. J.}, title = {Cosmic-ray-driven thermal modes in partially ionized viscous plasma with hall current}, volume = {981}, year = {2025}, }
• (2025). An in-depth study of gamma rays from the starburst galaxy m82 with VERITAS. ApJ, 981(2), 189. (www)

  @article{ , abstract = {Assuming Galactic cosmic rays originate in supernovae and the winds of massive stars, starburst galaxies should produce very-high-energy (VHE; E > 100 GeV) gamma-ray emission via the interaction of their copious quantities of cosmic rays with the large reservoirs of dense gas within the galaxies. Such VHE emission was detected by VERITAS from the starburst galaxy M82 in 2008–09. An extensive, multiyear campaign followed these initial observations, yielding a total of 254 hr of good-quality VERITAS data on M82. Leveraging modern analysis techniques and the larger exposure, these VERITAS data show a more statistically significant VHE signal (∼6.5 standard deviations, σ ). The corresponding photon spectrum is well fit by a power law (Γ = 2.3 ± 0.3 stat ± 0.2 sys ), and the observed integral flux is F (>450 GeV) = (3.2 ± 0.6 stat ± 0.6 sys ) × 10 −13 cm −2 s −1 , or ∼0.4% of the Crab Nebula flux above the same energy threshold. The improved VERITAS measurements, when combined with various multiwavelength data, enable modeling of the underlying emission and transport processes. A purely leptonic scenario is found to be a poor representation of the gamma-ray spectral energy distribution (SED). A lepto-hadronic scenario with cosmic rays following a power-law spectrum in momentum (index s ≃ 2.25) and with significant bremsstrahlung below 1 GeV provides a good match to the observed SED. The synchrotron emission from the secondary electrons indicates that efficient nonradiative losses of cosmic-ray electrons may be related to advective escape from the starburst core.}, archive = {J_ApJ}, author = {A. Acharyya and C. B. Adams and P. Bangale and J. T. Bartkoske and W. Benbow and J. H. Buckley and Y. Chen and J. L. Christiansen and A. J. Chromey and A. Duerr and M. Errando and M. Escobar Godoy and A. Falcone and S. Feldman and Q. Feng and J. Foote and L. Fortson and A. Furniss and W. Hanlon and D. Hanna and O. Hervet and C. E. Hinrichs and J. Holder and T. B. Humensky and W. Jin and M. N. Johnson and P. Kaaret and M. Kertzman and M. Kherlakian and D. Kieda and T. K. Kleiner and N. Korzoun and F. Krennrich and S. Kumar and M. J. Lang and M. Lundy and G. Maier and M. J. Millard and C. L. Mooney and P. Moriarty and R. Mukherjee and W. Ning and S. O’Brien and R. A. Ong and M. Pohl and E. Pueschel and J. Quinn and P. L. Rabinowitz and K. Ragan and P. T. Reynolds and D. Ribeiro and E. Roache and I. Sadeh and L. Saha and M. Santander and G. H. Sembroski and R. Shang and M. Splettstoesser and D. Tak and A. K. Talluri and J. V. Tucci and V. V. Vassiliev and D. A. Williams and S. L. Wong and J. Woo and (VERITAS Collaboration)}, doi = {10.3847/1538-4357/adab71}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {189}, shortjournal = {The Astrophys. J.}, title = {An in-depth study of gamma rays from the starburst galaxy m82 with VERITAS}, volume = {981}, year = {2025}, }
• (2025). BATSRUS GPU: Faster-than-real-time magnetospheric simulations with a block-adaptive grid code. ApJ, 981(2), 188. (www)

  @article{ , abstract = {Block-Adaptive-Tree Solar-wind Roe-type Upwind Scheme (BATSRUS), our state-of-the-art extended magnetohydrodynamic code, is the most used and one of the most resource-consuming models in the Space Weather Modeling Framework. It has always been our objective to improve its efficiency and speed with emerging techniques, such as GPU acceleration. To utilize the GPU nodes on modern supercomputers, we port BATSRUS to GPUs with the OpenACC API. Porting the code to a single GPU requires rewriting and optimizing the most used functionalities of the original code into a new solver, which accounts for around 1% of the entire program in length. To port it to multiple GPUs, we implement a new message-passing algorithm to support its unique block-adaptive grid feature. We conduct weak scaling tests on as many as 256 GPUs and find good performance. The program has 50%–60% parallel efficiency on up to 256 GPUs and up to 95% efficiency within a single node (four GPUs). Running large problems on more than one node has reduced efficiency due to hardware bottlenecks. We also demonstrate our ability to run representative magnetospheric simulations on GPUs. The performance for a single A100 GPU is about the same as 270 AMD "Rome" CPU cores (2.1 128-core nodes), and it runs 3.6 times faster than real time. The simulation can run 6.9 times faster than real time on four A100 GPUs.}, archive = {J_ApJ}, author = {Yifu An and Yuxi Chen and Hongyang Zhou and Alexander Gaenko and Gábor Tóth}, doi = {10.3847/1538-4357/adaf15}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {188}, shortjournal = {The Astrophys. J.}, title = {BATSRUS GPU: Faster-than-real-time magnetospheric simulations with a block-adaptive grid code}, volume = {981}, year = {2025}, }
• (2025). Characterizing the multiple protostellar system VLA 1623-2417 with JWST, ALMA, and VLA: Outflow origins, dust growth, and an unsettled disk. ApJ, 981(2), 187. (www)

  @article{ , abstract = {Utilizing the James Webb Space Telescope (JWST), the Atacama Large Millimeter/submillimeter Array (ALMA), and the Very Large Array (VLA), we present high angular resolution (0 \mathop{.}\limits^{^{\prime\prime} } 06–0 \mathop{.}\limits^{^{\prime\prime} } 42), multiwavelength (4 μ m–3 cm) observations of the VLA 1623-2417 protostellar system to characterize the origin, morphology and, properties of the continuum emission. JWST observations at 4.4 μ m reveal outflow cavities for VLA 1623 A and, for the first time, VLA 1623 B, as well as scattered light from the upper layers of the VLA 1623 W disk. We model the millimeter-centimeter spectral energy distributions to quantify the relative contributions of dust and ionized gas emission, calculate dust masses, and use spectral index maps to determine where optical depth hinders this analysis. In general, all objects appear to be optically thick down to ∼90 GHz, show evidence for significant amounts (tens to hundreds of M ⊕ ) of large (>1 mm) dust grains, and are dominated by ionized gas emission for frequencies ≲​​​​​​15 GHz. In addition, we find evidence of unsettled millimeter dust in the inclined disk of VLA 1623 B possibly attributed to instabilities within the circumstellar disk, adding to the growing catalog of unsettled Class 0/I disks. Our results represent some of the highest-resolution observations possible with current instrumentation, particularly in the case of the VLA. However, our interpretation is still limited at low frequencies (≲22 GHz) and thus motivates the need for next-generation interferometers operating at centimeter wavelengths.}, archive = {J_ApJ}, author = {Isaac C. Radley and Gemma Busquet and John D. Ilee and Hauyu Baobab Liu and Jaime E. Pineda and Klaus M. Pontoppidan and Enrique Macías and María José Maureira and Eleonora Bianchi and Tyler L. Bourke and Claudio Codella and Jan Forbrich and Josep M. Girart and Melvin G. Hoare and Ricardo Hernández Garnica and Izaskun Jiménez-Serra and Laurent Loinard and Jazmín Ordóñez-Toro and Linda Podio}, doi = {10.3847/1538-4357/adb0b9}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {187}, shortjournal = {The Astrophys. J.}, title = {Characterizing the multiple protostellar system VLA 1623-2417 with JWST, ALMA, and VLA: Outflow origins, dust growth, and an unsettled disk}, volume = {981}, year = {2025}, }
• (2025). Signature of a seyfert-like component in blazar 3C 273 and its reflection-based explanation. ApJ, 981(2), 186. (www)

  @article{ , abstract = {We present the results of blazar 3C 273 from simultaneous observations obtained using the XMM-Newton and NuSTAR satellites during the period 2015–2019 in five epochs. When the spectra are modeled with a power law, significant residuals arise below ∼2 keV and in the energy range of 30–78 keV in NuSTAR data. Residuals in the lower energy band represent soft X-ray excess, while at higher energies it likely represents a Compton reflection hump, which might be a weak component arising from dense and cold material. A faint iron line is present in XMM-Newton observations. We interpret such features as being attributed to the coronal emission plus those produced through reflection from an accretion disk. We model the spectral energy distributions (SEDs) with the single-zone inverse Compton (IC) jet model based on synchrotron self-Compton and external Compton phenomena. It is found that a one-zone synchrotron+IC model explains the SEDs quite well, but the jet component alone fails to fit the multiband X-ray emission for the low flux state of this object in 2018 and 2019, which arises owing to spectral flattening at low-energy X-rays, indicating that an additional Seyfert-like thermal component must be present at X-rays. This is further supported by a big blue bump present in the optical/UV band in all SEDs. Finally, we analyzed all the epochs using the relxill model to incorporate relativistic reflection and to model those residuals of soft excess and Compton hump in the X-ray bands.}, archive = {J_ApJ}, author = {Haritma Gaur and Main Pal and Muhammad S. Anjum and Kiran Wani and Pankaj Kushwaha and Ashwani Pandey and Liang Chen}, doi = {10.3847/1538-4357/adb0ca}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {186}, shortjournal = {The Astrophys. J.}, title = {Signature of a seyfert-like component in blazar 3C 273 and its reflection-based explanation}, volume = {981}, year = {2025}, }
• (2025). Temporal evolution of a network jet’s physical properties inferred from FISS/GST and IRIS observations. ApJ, 981(2), 185. (www)

  @article{ , abstract = {Small-scale jets, such as chromospheric and transition region (TR) network jets, are of great interest regarding coronal heating and solar wind acceleration. Spectroscopic analysis based on multiple spectral lines with different formation temperatures is essential for understanding the physical properties and driving mechanisms of jets. Here, we conduct an investigation of the physical properties of a small-scale chromospheric jet in a quiet-Sun network region and its TR counterpart. This jet is recorded from formation to extinction using the Fast Imaging Solar Spectrograph at the Goode Solar Telescope and the Interface Region Imaging Spectrograph. The chromospheric component of the jet exhibits a high line-of-sight speed of up to 45 km s −1 during its ascending phase, accompanied by spectral profiles akin to rapid blueshifted excursion and downflowing rapid redshifted excursion during the descending phase. Using a cloud model combined with a Multi-Layer Spectral Inversion, we quantify the jet's temperature during its ascending phase, which starts at approximately 11,000 K and increases by only 1000 K over 1 minute, much smaller than a few 10 4 K, the excess temperature expected in an ideal gas reconnection jet at an outflow speed of 45 km s −1 . The TR counterpart exhibits a Si iv 1394 Å line profile with a non-Gaussian shape, including a blueshifted component and a large nonthermal width. Our results suggest that if the jet is driven by magnetic reconnection in the chromosphere, the heat released by the reconnection may be mostly used to ionize the hydrogen rather than to increase the temperature so that the gas may appear almost isothermal.}, archive = {J_ApJ}, author = {Eun-Kyung Lim and Jongchul Chae and Kyuhyoun Cho and Vasyl Yurchyshyn and Heesu Yang and Kyung-Suk Cho and Hannah Kwak and Donguk Song and Maria S. Madjarska}, doi = {10.3847/1538-4357/adb1c3}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {185}, shortjournal = {The Astrophys. J.}, title = {Temporal evolution of a network jet’s physical properties inferred from FISS/GST and IRIS observations}, volume = {981}, year = {2025}, }
• (2025). Multifrequency radio observations of the dissociative cluster merger CIZA j0107.7+5408. ApJ, 981(2), 184. (www)

  @article{ , abstract = {We present new radio observations of the galaxy cluster merger CIZA J0107.7+5408 (CIZA0107), a large, roughly equal mass, postcore passage, dissociative binary system at z = 0.1066. CIZA0107 is an elongated, disturbed system, hosting two subclusters with optical galaxy number density peaks offset from their associated X-ray density peaks and double-peaked diffuse radio structure. We present new 240–470 MHz and 2.0–4.0 GHz Very Large Array observations of CIZA0107. We image the diffuse emission at high resolution, constrain its integrated spectrum, and map the spectral index distribution. We confirm the presence of steep-spectrum ( α ∼ −1.3) emission on a scale of ∼0.5 Mpc in both subclusters. We identify two smaller ultrasteep spectrum ( α < −2) regions, superimposed on larger-scale radio emission associated with the southwestern subcluster. At 340 MHz, we detect a radio edge bounding the emission to the south and show that it is coincident with a weak ( M ∼ 1.2) shock identified in the Chandra image. At 3 GHz, the emission does not show any corresponding edgelike feature, and in fact it extends beyond the shock. We investigate the nature of the emission in CIZA0107 and find that, while the system may host a double halo structure, we cannot rule out a scenario in which the emission arises from two relics projected on the central cluster regions.}, archive = {J_ApJ}, author = {Emma Schwartzman and Tracy E. Clarke and Simona Giacintucci and Wendy Peters and Scott W. Randall and Reinout J. van Weeren and Arnab Sarkar and Lawrence Rudnick and Elizabeth L. Blanton and Kyle Finner and Tony Mroczkowski and Paul Nulsen}, doi = {10.3847/1538-4357/adb1c5}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {184}, shortjournal = {The Astrophys. J.}, title = {Multifrequency radio observations of the dissociative cluster merger CIZA j0107.7+5408}, volume = {981}, year = {2025}, }
• (2025). On finding black holes in photometric microlensing surveys. ApJ, 981(2), 183. (www)

  @article{ , abstract = {There are expected to be millions of isolated black holes in the galaxy resulting from the deaths of massive stars. Measuring the abundance and properties of this remnant population would shed light on the end stages of stellar evolution and the evolution paths of black hole systems. Detecting isolated black holes is currently only possible via gravitational microlensing, which has so far yielded one definitive detection. The difficulty in finding microlensing black holes lies in having to choose a small subset of events, based on characteristics of their light curves, to allocate expensive and scarce follow-up resources to confirm the identity of the lens. Current methods either rely on simple cuts in parameter space without using the full distribution information or are only effective on small subsets of events. In this paper, we present a new lens classification method. The classifier takes in posterior constraints on light-curve parameters and combines them with a Galactic simulation to estimate the lens class probability. This method is flexible and can be used with any set of microlensing light-curve parameters, making it applicable to large samples of events. We make this classification framework available via the popclass Python package. We apply the classifier to ∼10,000 microlensing events from the Optical Gravitational Lensing Experiment survey and find 23 high-probability black hole candidates. Our classifier also suggests that the only known isolated black hole is an observational outlier, according to current Galactic models, and the allocation of astrometric follow-up on this event was a high-risk strategy.}, archive = {J_ApJ}, author = {Zofia Kaczmarek and Peter McGill and Scott E. Perkins and William A. Dawson and Macy Huston and Ming-Feng Ho and Natasha S. Abrams and Jessica R. Lu}, doi = {10.3847/1538-4357/adb1d7}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {183}, shortjournal = {The Astrophys. J.}, title = {On finding black holes in photometric microlensing surveys}, volume = {981}, year = {2025}, }
• (2025). Observation of cosmic-ray anisotropy in the southern hemisphere with 12 yr of data collected by the IceCube neutrino observatory. ApJ, 981(2), 182. (www)

  @article{ , abstract = {We analyzed the 7.92 × 10 11 cosmic-ray-induced muon events collected by the IceCube Neutrino Observatory from 2011 May 13, when the fully constructed experiment started to take data, to 2023 May 12. This data set provides an up-to-date cosmic-ray arrival direction distribution in the Southern Hemisphere with unprecedented statistical accuracy covering more than a full period length of a solar cycle. Improvements in Monte Carlo event simulation and better handling of year-to-year differences in data processing significantly reduce systematic uncertainties below the level of statistical fluctuations compared to the previously published results. We confirm the observation of a change in the angular structure of the cosmic-ray anisotropy between 10 TeV and 1 PeV, more specifically in the 100–300 TeV energy range. For the first time, we analyzed the angular power spectrum at different energies. The observed variations of the power spectra with energy suggest relatively reduced large-scale features at high energy compared to those of medium and small scales. The large volume of data enhances the statistical significance at higher energies, up to the PeV scale, and smaller angular scales, down to approximately 6° compared to previous findings.}, archive = {J_ApJ}, author = {R. Abbasi and M. Ackermann and J. Adams and S. K. Agarwalla and T. Aguado and J. A. Aguilar and M. Ahlers and J. M. Alameddine and N. M. Amin and K. Andeen and C. Argüelles and Y. Ashida and S. Athanasiadou and S. N. Axani and R. Babu and X. Bai and A. Balagopal V. and M. Baricevic and S. W. Barwick and S. Bash and V. Basu and R. Bay and J. J. Beatty and J. Becker Tjus and J. Beise and C. Bellenghi and S. BenZvi and D. Berley and E. Bernardini and D. Z. Besson and E. Blaufuss and L. Bloom and S. Blot and F. Bontempo and J. Y. Book Motzkin and C. Boscolo Meneguolo and S. Böser and O. Botner and J. Böttcher and J. Braun and B. Brinson and Z. Brisson-Tsavoussis and J. Brostean-Kaiser and L. Brusa and R. T. Burley and D. Butterfield and M. A. Campana and I. Caracas and K. Carloni and J. Carpio and S. Chattopadhyay and N. Chau and Z. Chen and D. Chirkin and S. Choi and B. A. Clark and C. Cochling and A. Coleman and P. Coleman and G. H. Collin and A. Connolly and J. M. Conrad and R. Corley and D. F. Cowen and C. De Clercq and J. J. DeLaunay and D. Delgado and S. Deng and A. Desai and P. Desiati and K. D. de Vries and G. de Wasseige and T. DeYoung and A. Diaz and J. C. Díaz-Vélez and P. Dierichs and M. Dittmer and A. Domi and L. Draper and H. Dujmovic and D. Durnford and K. Dutta and M. A. DuVernois and T. Ehrhardt and L. Eidenschink and A. Eimer and P. Eller and E. Ellinger and S. El Mentawi and D. Elsässer and R. Engel and H. Erpenbeck and J. Evans and P. A. Evenson and K. L. Fan and K. Fang and K. Farrag and A. R. Fazely and A. Fedynitch and N. Feigl and S. Fiedlschuster and C. Finley and L. Fischer and D. Fox and A. Franckowiak and S. Fukami and P. Fürst and J. Gallagher and E. Ganster and A. Garcia and M. Garcia and G. Garg and E. Genton and L. Gerhardt and A. Ghadimi and C. Girard-Carillo and C. Glaser and T. Glüsenkamp and J. G. Gonzalez and S. Goswami and A. Granados and D. Grant and S. J. Gray and S. Griffin and S. Griswold and K. M. Groth and K. Gruchot and D. Guevel and C. Günther and P. Gutjahr and C. Ha and C. Haack and A. Hallgren and L. Halve and F. Halzen and L. Hamacher and H. Hamdaoui and A. Hardy and W. Hayes and M. Ha Minh and M. Handt and K. Hanson and J. Hardin and A. A. Harnisch and P. Hatch and A. Haungs and J. Häussler and K. Helbing and J. Hellrung and J. Hermannsgabner and L. Heuermann and N. Heyer and S. Hickford and A. Hidvegi and C. Hill and G. C. Hill and R. Hmaid and K. D. Hoffman and S. Hori and K. Hoshina and M. Hostert and W. Hou and T. Huber and K. Hultqvist and M. Hünnefeld and R. Hussain and K. Hymon and A. Ishihara and W. Iwakiri and M. Jacquart and S. Jain and O. Janik and M. Jansson and M. Jeong and M. Jin and B. J. P. Jones and N. Kamp and D. Kang and W. Kang and X. Kang and A. Kappes and D. Kappesser and L. Kardum and T. Karg and M. Karl and A. Karle and A. Katil and U. Katz and M. Kauer and J. L. Kelley and M. Khanal and A. Khatee Zathul and A. Kheirandish and J. Kiryluk and S. R. Klein and Y. Kobayashi and A. Kochocki and R. Koirala and H. Kolanoski and T. Kontrimas and L. Köpke and C. Kopper and D. J. Koskinen and P. Koundal and M. Kowalski and T. Kozynets and N. Krieger and J. Krishnamoorthi and K. Kruiswijk and E. Krupczak and A. Kumar and E. Kun and N. Kurahashi and N. Lad and C. Lagunas Gualda and M. Lamoureux and M. J. Larson and F. Lauber and J. P. Lazar and J. W. Lee and K. Leonard DeHolton and A. Leszczyńska and J. Liao and M. Lincetto and Y. T. Liu and M. Liubarska and C. Love and L. Lu and F. Lucarelli and W. Luszczak and Y. Lyu and J. Madsen and E. Magnus and K. B. M. Mahn and Y. Makino and E. Manao and S. Mancina and A. Mand and W. Marie Sainte and I. C. Mariş and S. Marka and Z. Marka and M. Marsee and I. Martinez-Soler and R. Maruyama and F. Mayhew and F. McNally and J. V. Mead and K. Meagher and S. Mechbal and A. Medina and M. Meier and Y. Merckx and L. Merten and J. Mitchell and T. Montaruli and R. W. Moore and Y. Morii and R. Morse and M. Moulai and A. Moy and T. Mukherjee and R. Naab and M. Nakos and U. Naumann and J. Necker and A. Negi and L. Neste and M. Neumann and H. Niederhausen and M. U. Nisa and K. Noda and A. Noell and A. Novikov and A. Obertacke Pollmann and V. O’Dell and A. Olivas and R. Orsoe and J. Osborn and E. O’Sullivan and V. Palusova and H. Pandya and N. Park and G. K. Parker and V. Parrish and E. N. Paudel and L. Paul and C. Pérez de los Heros and T. Pernice and J. Peterson and A. Pizzuto and M. Plum and A. Pontén and Y. Popovych and M. Prado Rodriguez and B. Pries and R. Procter-Murphy and G. T. Przybylski and L. Pyras and C. Raab and J. Rack-Helleis and N. Rad and M. Ravn and K. Rawlins and Z. Rechav and A. Rehman and E. Resconi and S. Reusch and W. Rhode and B. Riedel and A. Rifaie and E. J. Roberts and S. Robertson and S. Rodan and G. Roellinghoff and M. Rongen and A. Rosted and C. Rott and T. Ruhe and L. Ruohan and D. Ryckbosch and I. Safa and J. Saffer and D. Salazar-Gallegos and P. Sampathkumar and A. Sandrock and M. Santander and S. Sarkar and J. Savelberg and P. Savina and P. Schaile and M. Schaufel and H. Schieler and S. Schindler and L. Schlickmann and B. Schlüter and F. Schlüter and N. Schmeisser and E. Schmidt and T. Schmidt and J. Schneider and F. G. Schröder and L. Schumacher and S. Schwirn and S. Sclafani and D. Seckel and L. Seen and M. Seikh and M. Seo and S. Seunarine and P. Sevle Myhr and R. Shah and S. Shefali and N. Shimizu and M. Silva and A. Simmons and B. Skrzypek and B. Smithers and R. Snihur and J. Soedingrekso and A. Søgaard and D. Soldin and P. Soldin and G. Sommani and C. Spannfellner and G. M. Spiczak and C. Spiering and J. Stachurska and M. Stamatikos and T. Stanev and T. Stezelberger and T. Stürwald and T. Stuttard and G. W. Sullivan and I. Taboada and S. Ter-Antonyan and A. Terliuk and M. Thiesmeyer and W. G. Thompson and A. Thorpe and J. Thwaites and S. Tilav and K. Tollefson and C. Tönnis and S. Toscano and D. Tosi and A. Trettin and R. Turcotte and M. A. Unland Elorrieta and A. K. Upadhyay and K. Upshaw and A. Vaidyanathan and N. Valtonen-Mattila and J. Vandenbroucke and N. van Eijndhoven and D. Vannerom and J. van Santen and J. Vara and F. Varsi and J. Veitch-Michaelis and M. Venugopal and M. Vereecken and S. Vergara Carrasco and S. Verpoest and D. Veske and A. Vijai and C. Walck and A. Wang and C. Weaver and P. Weigel and A. Weindl and J. Weldert and A. Y. Wen and C. Wendt and J. Werthebach and M. Weyrauch and N. Whitehorn and C. H. Wiebusch and D. R. Williams and L. Witthaus and H. Woodward and M. Wolf and G. Wrede and X. W. Xu and J. P. Yanez and E. Yildizci and S. Yoshida and R. Young and S. Yu and T. Yuan and A. Zegarelli and S. Zhang and Z. Zhang and P. Zhelnin and P. Zilberman and M. Zimmerman and (IceCube Collaboration)}, doi = {10.3847/1538-4357/adb1de}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {182}, shortjournal = {The Astrophys. J.}, title = {Observation of cosmic-ray anisotropy in the southern hemisphere with 12 yr of data collected by the IceCube neutrino observatory}, volume = {981}, year = {2025}, }
• (2025). Evaluating short-warning mitigation via intentional robust disruption of a hypothetical impact of asteroid 2023 NT1. ApJ, 981(2), 181. (www)

  @article{ , abstract = {We investigate various short-warning mitigation scenarios via fragmentation for a hypothetical impact of asteroid 2023 NT1, a near-Earth object (NEO) that was discovered on 2023 July 15, two days after its closest approach to Earth on July 13. The asteroid passed by Earth within ∼0.25 lunar distances, with a closest approach of ∼1 × 10 5 km and a velocity of 11.27 km s −1 . Its size remains largely uncertain, with an estimated diameter range of 26–58 m and a most probable estimate of 34 m (JPL Sentry, 2023 September 15; weighted by the NEO size frequency distribution). If 2023 NT1 had collided with Earth, it could have caused significant local damage. Assuming a spherical asteroid with a diameter of 34 m, uniform density of 2.6 g cm −3 , and impact velocity of 15.59 km s −1 , a collision would have yielded an estimated impact energy of ∼1.5 Mt, approximately 3 times the energy of the Chelyabinsk airburst in 2013. We analyze the effectiveness of mitigation via intentional robust disruption for objects similar to 2023 NT1. We utilize Pulverize It (PI), a NASA Innovative Advanced Concepts study of planetary defense via fragmentation, to model potential mitigation scenarios through simulations of hypervelocity asteroid disruption and atmospheric ground effects in the case of a terminal defense mode. Simulations suggest that PI is an effective multimodal approach for planetary defense that can operate in extremely short interdiction modes, in addition to long interdiction timescales with extended warning. Our simulations support the proposition that threats like 2023 NT1 can be effectively mitigated with intercepts of 1 day (or less) prior to impact, yielding minimal to no ground damage.}, archive = {J_ApJ}, author = {Brin Bailey and Alexander N. Cohen and Sasha Egan and Philip Lubin and Ruitao Xu and Mark Boslough and Darrel Robertson and Elizabeth A. Silber and Irina Sagert and Oleg Korobkin and Glenn Sjoden}, doi = {10.3847/1538-4357/adb289}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {181}, shortjournal = {The Astrophys. J.}, title = {Evaluating short-warning mitigation via intentional robust disruption of a hypothetical impact of asteroid 2023 NT1}, volume = {981}, year = {2025}, }
• (2025). Photoevaporation from inner protoplanetary disks confronted with observations. ApJ, 981(2), 180. (www)

  @article{ , abstract = {The decades-long explorations on the dispersal of protoplanetary disks involve many debates about photoevaporation versus magnetized wind launching mechanisms. This work argues that the observed winds originating from the inner disk ( R ≲ 0.3 au) cannot be explained by the photoevaporative mechanism. Heating the gas to proper temperatures for the observed forbidden lines (especially [O i ] λ 6300) will overionize it, suppressing the abundances of species responsible for the emission. Even if adequate emissivity is achieved by fine-tuning the physical parameters, the total cooling power will become unattainable by the radiative heating alone. Energy conservation requires the presumed photoevaporative winds to be heated to ≳10 5 K when launched from inner disks. However, due to efficient thermal accommodation with dust grains and cooling processes at high densities, X-ray irradiation at energies above 1 keV cannot efficiently launch winds in the first place because of its high penetration. Some studies claiming X-ray wind launching have oversimplified the thermochemical couplings. Confirmed by semianalytic integrations of thermochemical fluid structures, such high ionizations contradict the observed emission of neutral and singly ionized atoms from the winds originating from the inner disks.}, archive = {J_ApJ}, author = {Yiren Lin and Lile Wang and Min Fang and Ahmad Nemer and Jeremy Goodman}, doi = {10.3847/1538-4357/adb396}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {180}, shortjournal = {The Astrophys. J.}, title = {Photoevaporation from inner protoplanetary disks confronted with observations}, volume = {981}, year = {2025}, }
• (2025). Milky way classical cepheid distances from calibrated infrared Period–Luminosity–Metallicity relations. ApJ, 981(2), 179. (www)

  @article{ , abstract = {Classical Cepheids (DCEPs) serve as fundamental standard candles for measuring cosmic distances and investigating the structure and evolution of the Milky Way disk. However, accurate distance estimation faces challenges due to severe extinction, particularly toward the Galactic center. Although the Gaia Wesenheit magnitude reduces extinction effects, its reliance on a constant optical extinction law introduces significant uncertainties in regions of heavy obscuration. Infrared period–luminosity relations, combined with 3D extinction maps, offer an alternative, but these maps become unreliable beyond approximately 5 kpc. In this work, we calibrate the period–luminosity–metallicity (PLZ) relations for DCEPs across three near-infrared bands ( J , H , K S ) and four mid-infrared bands (W1, W2, [3.6], and [4.5]). This includes the first calibration of the W1 and W2 bands. To correct for extinction, we employ the infrared multi-passband optimal distance method and the BP–RP method, which complement and validate each other. These homogeneous PLZ relations, combined with reliable extinction corrections, yield the most accurate Galactic DCEP distances to date, covering 3452 DCEPs with an average relative distance error of 3.1%.}, archive = {J_ApJ}, author = {Huajian Wang and Xiaodian Chen}, doi = {10.3847/1538-4357/adb39d}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {179}, shortjournal = {The Astrophys. J.}, title = {Milky way classical cepheid distances from calibrated infrared Period–Luminosity–Metallicity relations}, volume = {981}, year = {2025}, }
• (2025). Origin of the unusual composition of 3He-rich solar energetic particles. ApJ, 981(2), 178. (www)

  @article{ , abstract = {We examine 3 He-rich solar energetic particles (SEPs) detected on 2023 October 24–25 by Solar Orbiter at 0.47 au. Measurements reveal that heavy-ion enhancements increase irregularly with mass, peaking at S. C, and especially N, Si, and S, stand out in the enhancement pattern with large abundances. Except for 3 He, heavy-ion spectra can only be measured below 0.5 MeV nucleon −1 . At 0.386 MeV nucleon −1 , the event shows a huge 3 He/ 4 He ratio of 75.2 ± 33.9, larger than previously observed. Solar Dynamics Observatory extreme-ultraviolet data show a minifilament eruption at the solar source of 3 He-rich SEPs that triggered a straight tiny jet. Located at the boundary of a low-latitude coronal hole, the jet base is a bright, small-scale region with a supergranulation scale size. The emission measure (EM) provides relatively cold source temperatures of 1.5–1.7 MK between the filament eruption and nonthermal type III radio burst onset. Analysis suggests that the EM distribution of temperature in the solar source could be a factor that affects the preferential selection of heavy ions for heating or acceleration, thus shaping the observed enhancement pattern. Including previously reported similar events indicates that the eruption of the minifilament is a common feature of events with heavy-ion enhancement not ordered by mass. Surprisingly, sources with weak magnetic fields show extreme 3 He enrichment in these events. Moreover, the energy attained by heavy ions seems to be influenced by the size and form of the jets.}, archive = {J_ApJ}, author = {Radoslav Bučík and Glenn M. Mason and Sargam M. Mulay and George C. Ho and Robert F. Wimmer-Schweingruber and Javier Rodríguez-Pacheco}, doi = {10.3847/1538-4357/adb48d}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {178}, shortjournal = {The Astrophys. J.}, title = {Origin of the unusual composition of 3He-rich solar energetic particles}, volume = {981}, year = {2025}, }
• (2025). The origin channels of hierarchical binary black hole mergers in the LIGO–Virgo–KAGRA o1, o2, and o3 runs. ApJ, 981(2), 177. (www)

  @article{ , abstract = {We infer the origin channels of hierarchical mergers observed in the LIGO–Virgo–KAGRA (LVK) O1, O2, and O3 runs using a hierarchical Bayesian analysis under a parametric population model. By assuming the active galactic nucleus (AGN) disk and nuclear star cluster (NSC) channels, we find that NSCs likely dominate the hierarchical merger rate in the Universe, corresponding to a fraction of {f}_{{\rm{NSC}}}=0.8{7}_{-0.29}^{+0.10} at 90% credible intervals in our fiducial model; AGN disks may contribute up to nearly half of hierarchical mergers detectable with LVK, specifically {f}_{{\rm{\det }},{\rm{AGN}}}=0.3{4}_{-0.26}^{+0.38} . We investigate the impact of the escape speed, along with other population parameters on the branching fraction, suggesting that the mass, mass ratio, and spin of the sources play significant roles in population analysis. We show that hierarchical mergers constitute at least ∼10% of the gravitational-wave events detected by LVK during the O1–O3 runs. Furthermore, we demonstrate that it is challenging to effectively infer detailed information about the host environment based solely on the distribution of black hole merger parameters if multiple formation channels are considered.}, archive = {J_ApJ}, author = {Guo-Peng Li and Xi-Long Fan}, doi = {10.3847/1538-4357/adb578}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {177}, shortjournal = {The Astrophys. J.}, title = {The origin channels of hierarchical binary black hole mergers in the LIGO–Virgo–KAGRA o1, o2, and o3 runs}, volume = {981}, year = {2025}, }
• (2025). The effect of rotation on triggering s doradus instabilities in luminous blue variables. ApJ, 981(2), 176. (www)

  @article{ , abstract = {Luminous blue variables (LBVs) are an intermediate stage in the evolution of high-mass stars characterized by extreme mass loss and substantial variability. The stars show large irregular episodic variations on timescales of years to decades in their effective temperatures (called "S Dor variations"). Observations show that these variations are triggered when the stars are in a well-defined strip in the H-R diagram that corresponds to the Modified Eddington Limit, where the atmospheric radiation pressure almost balances gravity. In this work we consider the role that rotation plays in the instability that leads to the triggering of S Dor variations in luminous post-main-sequence LBVs. We adopt the existing instability criterion that the effective surface gravity is reduced to 10% of the Newtonian gravity due to radiation pressure in the atmosphere of nonrotating stars. We then specifically describe how rotation impacts this instability. By carrying out numerical simulations of model LBVs at both solar and subsolar metallicities, we confirm that most LBVs should be unstable at both the equator and the poles, and that rotation exacerbates this effect; some models also produce enhanced mass loss at the pole or equator. Our numerical models also predict dense equatorial disks or rings and high-velocity bipolar outflows, in agreement with existing observations of LBV circumstellar nebulae.}, archive = {J_ApJ}, author = {Emily M. Levesque and Henny J. G. L. M. Lamers and Alex de Koter}, doi = {10.3847/1538-4357/adb581}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {176}, shortjournal = {The Astrophys. J.}, title = {The effect of rotation on triggering s doradus instabilities in luminous blue variables}, volume = {981}, year = {2025}, }
• (2025). New potential ultracompact X-ray binaries for space-based gravitational-wave detectors from a low-mass main-sequence companion channel. ApJ, 981(2), 175. (www)

  @article{ , abstract = {We investigate the formation and evolution of ultracompact X-ray binaries (UCXBs) using the COMPAS binary evolution code, starting from the zero-age main sequence (MS). Focusing on the low-mass MS companion channel, we simulate gravitational-wave (GW) signals from UCXBs with LEGWORK and evaluate their detectability by space-based observatories such as Taiji and TianQin. By incorporating signal-to-noise ratio (SNR) calculations with a threshold of SNR > 5, we provide a realistic framework to assess the detectability of the GW source. Our analysis suggests that the Milky Way currently hosts 7–32 observable UCXBs from the MS companion channel. Taiji or LISA alone could detect one to six sources over an 8 yr observation period, while TianQin, due to its high-frequency sensitivity, contributes to detecting systems with extremely short orbital periods and can also detect one to four sources. Comparison with sensitivity curves validates UCXBs as detectable GW sources, particularly at greater Galactic distances. This study improves our understanding of the evolution of UCXBs and their role as GW sources. By integrating population synthesis, SNR-based analyses, and observational data, we establish UCXBs as significant targets for GW astronomy, paving the way for future missions and theoretical studies of compact binary systems.}, archive = {J_ApJ}, author = {Minghua Chen and Jinzhong Liu}, doi = {10.3847/1538-4357/adb618}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {175}, shortjournal = {The Astrophys. J.}, title = {New potential ultracompact X-ray binaries for space-based gravitational-wave detectors from a low-mass main-sequence companion channel}, volume = {981}, year = {2025}, }
• (2025). The source of the 2017 cosmic-ray half-year modulation event. ApJ, 981(2), 174. (www)

  @article{ , abstract = {In 2017, as the solar cycle approached solar minimum, an unusually long and large depression was observed in galactic cosmic-ray (GCR) protons, detected with the Alpha Magnetic Spectrometer, lasting for the second half of that year. The depression, as seen in the Bartel-rotation-averaged proton flux, has the form of a Forbush decrease (FD). Despite this resemblance, however, the cause of the observed depression does not have such a simple explanation as an FD, due to coronal mass ejections (CMEs), which typically last for a few days at 1 au rather than half a year. In this work, we seek the cause of the observed depression and investigate two main possibilities. First, we consider a minicycle—a temporary change in the solar dynamo that changes the behavior of the global solar magnetic field and, by this, the modulation of GCRs. Second, we investigate the behavior of solar activity, both CMEs and corotating/stream interaction regions (CIRs/SIRs), during this period. Our findings show that although there is some evidence for minicycle behavior prior to the depression, the depression is ultimately due to a combination of recurrent CMEs, SIRs, and CIRs. A particular characteristic of the depression is that the largest impacts that help to create and maintain it are due to four CMEs from the same, highly active, magnetic source that persists for several solar rotations. This active magnetic source is unusual, given the closeness of the solar cycle to solar minimum, which also helps to make the depression more evident.}, archive = {J_ApJ}, author = {O. P. M. Aslam and D. MacTaggart and R. Battiston and M. S. Potgieter and M. D. Ngobeni}, doi = {10.3847/1538-4357/adb61c}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {174}, shortjournal = {The Astrophys. J.}, title = {The source of the 2017 cosmic-ray half-year modulation event}, volume = {981}, year = {2025}, }
• (2025). Anticorrelation between flux and photon index of hard-X-ray emission from the crab. ApJ, 981(2), 173. (www)

  @article{ , abstract = {Using Swift Burst Alert Telescope event-mode data during gamma-ray burst occurrences, we conduct spectral analysis for the Crab system. From 38 good observations, which span a period of 18 yr from 2006 to 2023, we find that the Crab's X-ray flux not only flickers but also significantly anticorrelates to its spectral power-law photon index. Since the emission contribution of the Crab pulsar in this energy range is small, this anticorrelation is mainly about the emission of the Crab nebula. We suggest that this anticorrelation provides observational supporting evidence for the long-standing notion that the nebula emission is due to synchrotron radiation of shocked pulsar winds in the nebula.}, archive = {J_ApJ}, author = {Koothodil Abhijith Augustine and Hsiang-Kuang Chang}, doi = {10.3847/1538-4357/adb70e}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {173}, shortjournal = {The Astrophys. J.}, title = {Anticorrelation between flux and photon index of hard-X-ray emission from the crab}, volume = {981}, year = {2025}, }
• (2025). Experimental and numerical studies of the collapse of dense clouds induced by Herbig–Haro stellar jets. ApJ, 981(2), 172. (www)

  @article{ , abstract = {This study investigates the influence of Herbig–Haro jets on initiating star formation in dense environments. When molecular clouds are nearing gravitational instability, the impact of a protostellar jet could provide the impetus needed to catalyze star formation. A high-energy-density experiment was carried out at the LULI2000 laser facility, where a supersonic jet generated by a nanosecond laser was used to compress a foam or plastic ball, mimicking the interaction of a Herbig–Haro jet with a molecular cloud. Simulations using the 3D radiation hydrodynamics code TROLL provided comprehensive data for analyzing ball compression and calculating jet characteristics. After applying scaling laws, similarities between stellar and experimental jets were explored. Diagnostic simulations—including density gradient, emission, and X-ray radiographies—showed strong agreement with experimental data. The results of the experiment, supported by simulations, demonstrate that the impact of a protostellar jet on a molecular cloud could reduce the Bonnor–Ebert mass by approximately 9%, thereby initiating collapse.}, archive = {J_ApJ}, author = {Marin Fontaine and Clotilde Busschaert and Yaniss Benkadoum and Isabeau A. Bertrix and Michel Koenig and Frédéric Lefèvre and Jean-Raphaël Marquès and Diego Oportus and Akihiko Ikeda and Yasuhiro H. Matsuda and Émeric Falize and Bruno Albertazzi}, doi = {10.3847/1538-4357/adb715}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {172}, shortjournal = {The Astrophys. J.}, title = {Experimental and numerical studies of the collapse of dense clouds induced by Herbig–Haro stellar jets}, volume = {981}, year = {2025}, }
• (2025). Physical origins of outflowing cold clouds in local star-forming dwarf galaxies. ApJ, 981(2), 171. (www)

  @article{ , abstract = {We study the physical origins of outflowing cold clouds in a sample of 14 low-redshift dwarf ( M * ≲ 10 10 M ⊙ ) galaxies from the Cosmic Origins Spectrograph Legacy Archive Spectroscopic SurveY (CLASSY) using Keck/ESI data. Outflows are traced by broad (FWHM  ∼260 km s −1 ) and very-broad (VB; FWHM ∼1200 km s −1 ) velocity components in strong emission lines like [O iii ] λ 5007 and H α . The maximum velocities ( {v}_{{\rm{\max }}} ) of broad components correlate positively with star formation rate, unlike the anticorrelation observed for VB components, and are consistent with superbubble models. In contrast, supernova-driven galactic wind models better reproduce the {v}_{{\rm{\max }}} of VB components. Direct radiative cooling from a hot wind significantly underestimates the luminosities of both broad and VB components. A multiphase wind model with turbulent radiative mixing reduces this discrepancy to at least 1 dex for most VB components. Stellar photoionization likely provides additional energy since broad components lie in the starburst locus of excitation diagnostic diagrams. We propose a novel interpretation of outflow origins in star-forming dwarf galaxies—broad components trace expanding superbubble shells, while VB components originate from galactic winds. One-zone photoionization models fail to explain the low-ionization lines ([S ii ] and [O i ]) of broad components near the maximal starburst regime, which two-zone photoionization models with density-bounded channels instead reproduce. These two-zone models indicate anisotropic leakage of Lyman continuum photons through low-density channels formed by expanding superbubbles. Our study highlights extreme outflows ( {v}_{{\rm{\max }}}\gtrsim 1000\,{\rm{km}}\,{{\rm{s}}}^{-1} ) in nine out of 14 star-forming dwarf galaxies, comparable to active galactic nucleus–driven winds.}, archive = {J_ApJ}, author = {Zixuan Peng and Crystal L. Martin and Zirui Chen and Drummond B. Fielding and Xinfeng Xu and Timothy Heckman and Lise Ramambason and Yuan Li and Cody Carr and Weida Hu and Zuyi Chen and Claudia Scarlata and Alaina Henry}, doi = {10.3847/1538-4357/ada606}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {171}, shortjournal = {The Astrophys. J.}, title = {Physical origins of outflowing cold clouds in local star-forming dwarf galaxies}, volume = {981}, year = {2025}, }
• (2025). Cosmological and astrophysical parameter inference from stacked galaxy cluster profiles using CAMELS-zoomGZ. ApJ, 981(2), 170. (www)

  @article{ , abstract = {We present a study on the inference of cosmological and astrophysical parameters using stacked galaxy cluster profiles. Utilizing the CAMELS-zoomGZ simulations, we explore how various cluster properties—such as X-ray surface brightness, gas density, temperature, metallicity, and Compton-y profiles—can be used to predict parameters within the 28-dimensional parameter space of the IllustrisTNG model. Through neural networks, we achieve a high correlation coefficient of 0.97 or above for all cosmological parameters, including Ω m , H 0 , and σ 8 , and over 0.90 for the remaining astrophysical parameters, showcasing the effectiveness of these profiles for parameter inference. We investigate the impact of different radial cuts, with bins ranging from 0.1 R 200 c to 0.7 R 200 c , to simulate current observational constraints. Additionally, we perform a noise sensitivity analysis, adding up to 40% Gaussian noise (corresponding to signal-to-noise ratios as low as 2.5), revealing that key parameters such as Ω m , H 0 , and the initial mass function slope remain robust even under extreme noise conditions. We also compare the performance of full radial profiles against integrated quantities, finding that profiles generally lead to more accurate parameter inferences. Our results demonstrate that stacked galaxy cluster profiles contain crucial information on both astrophysical processes within groups and clusters and the underlying cosmology of the Universe. This underscores their significance for interpreting the complex data expected from next-generation surveys and reveals, for the first time, their potential as a powerful tool for parameter inference.}, archive = {J_ApJ}, author = {Elena Hernández-Martínez and Shy Genel and Francisco Villaescusa-Navarro and Ulrich P. Steinwandel and Max E. Lee and Erwin T. Lau and David N. Spergel}, doi = {10.3847/1538-4357/ada9e9}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {170}, shortjournal = {The Astrophys. J.}, title = {Cosmological and astrophysical parameter inference from stacked galaxy cluster profiles using CAMELS-zoomGZ}, volume = {981}, year = {2025}, }
• (2025). Starspot distribution and flare events in two young low-mass stars using TESS data. ApJ, 981(2), 169. (www)

  @article{ , abstract = {Wide-field high-precision photometric observations such as the Transiting Exoplanet Survey Satellite (TESS) allowed the investigation of the stellar magnetic activity of cool stars. M dwarf starspots and stellar flares are the main indicators of magnetic activity. The present study focuses on modeling light curves (LCs) to analyze the distribution and characteristics of starspots, e.g., location, temperature, and spot size. The TESS LCs of two selected young M dwarfs, i.e., GJ 182 and 2MASS J05160212+2214528, were reconstructed using the Best rAndom StarSpots Model calculAtioN software, obtaining a three-spot model for GJ 182 and two-spot model for 2MASS J05160212+2214528, describing their LCs. For GJ 182, the mean spot temperature was estimated to be approximately 3279 K, covering 5%–8.5% of the stellar surface, while for 2MASS J05160212+2214528, the average spot temperature was approximately 2631 K, with a mean spottedness of about 5.4%. Using the 2 minute cadence LC data, we identified and analyzed 48 flare events from GJ 182, while no flares were detected in 2MASS J05160212+2214528. The estimated bolometric flare energy ranges from 10 32 to 10 35 erg, while in the TESS bandpass, it ranges from 10 31 to 10 33 erg. We derived the power-law index of −1.53 ± 0.12 and −1.86 ± 0.22 for flare frequency distribution in sectors 5 and 32, respectively, in the flare energy range 10 33 –10 35 erg, consistent with previous studies for M dwarfs. A positive linear correlation between flare energy and duration was found with a slope of 0.67 ± 0.02, suggesting a similar mechanism followed by stellar superflares and solar flares. By assuming the similarities with solar flares, we also estimated a lower limit of the magnetic field strength of around 12–232 G to produce such superflare events.}, archive = {J_ApJ}, author = {Rajib Kumbhakar and Soumen Mondal and Samrat Ghosh and Diya Ram}, doi = {10.3847/1538-4357/adae07}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {169}, shortjournal = {The Astrophys. J.}, title = {Starspot distribution and flare events in two young low-mass stars using TESS data}, volume = {981}, year = {2025}, }
• (2025). Using convolutional neural networks to search for strongly lensed quasars in KiDS DR5. ApJ, 981(2), 168. (www)

  @article{ , abstract = {Gravitationally strongly lensed quasars (SL-QSO) offer invaluable insights into cosmological and astrophysical phenomena. With the data from ongoing and next-generation surveys, thousands of SL-QSO systems can be discovered expectedly, leading to unprecedented opportunities. However, the challenge lies in identifying SL-QSO from enormous data sets with high recall and purity in an automated and efficient manner. Hence, we developed a program based on a convolutional neural network (CNN) for finding SL-QSO from large-scale surveys and applied it to the Kilo-degree Survey Data Release 5. Our approach involves three key stages: first, we preselected 10 million bright objects (with r -band MAG_AUTO <  22), excluding stars from the data set; second, we established realistic training and test sets to train and fine-tune the CNN, resulting in the identification of 4195 machine candidates, and the false-positive rate of ∼1/2000 and recall of 0.8125 evaluated by using the real test set containing 16 confirmed lensed quasars; third, human inspections were performed for further selections, and then, 272 SL-QSO candidates were eventually found in total, including 16 high-score, 118 median-score, and 138 lower-score candidates, separately. Removing the systems already confirmed or identified in other papers, we end up with 229 SL-QSO candidates, including 7 high-score, 95 median-score, and 127 lower-score candidates, and the corresponding catalog is publicly available online ( https://github.com/EigenHermit/H24 ). We have also included an excellent quad candidate in the Appendix , discovered serendipitously during the fine-tuning process of the CNN.}, archive = {J_ApJ}, author = {Zizhao He and Rui Li and Yiping Shu and Crescenzo Tortora and Xinzhong Er and Raoul Cañameras and Stefan Schuldt and Nicola R. Napolitano and Bharath Chowdhary N and Qihang Chen and Nan Li and Haicheng Feng and Limeng Deng and Guoliang Li and L. V. E. Koopmans and Andrej Dvornik}, doi = {10.3847/1538-4357/adaf28}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {168}, shortjournal = {The Astrophys. J.}, title = {Using convolutional neural networks to search for strongly lensed quasars in KiDS DR5}, volume = {981}, year = {2025}, }
• (2025). The AURORA survey: An extraordinarily mature, star-forming galaxy at z ∼ 7. ApJ, 981(2), 167. (www)

  @article{ , abstract = {We present the properties of a massive, large, dusty, metal-rich, star-forming galaxy at z spec = 6.73. GOODSN-100182 was observed with JWST/NIRSpec as part of the Assembly of Ultradeep Rest-optical Observations Revealing Astrophysics (AURORA) survey, and is also covered by public multiwavelength Hubble Space Telescope and JWST imaging. While the large stellar mass of GOODSN-100182 (∼10 10 M ⊙ ) was indicated prior to JWST, NIRCam rest-frame optical imaging now reveals the presence of an extended disk ( r eff ∼ 1.5 kpc). In addition, the NIRSpec R ∼ 1000 spectrum of GOODSN-100182 includes the detection of a large suite of rest-frame optical nebular emission lines ranging in wavelength from [O ii ] λ 3727 up to [N ii ] λ 6583. The ratios of Balmer lines suggest significant dust attenuation ( E{(B-V)}_{{\rm{gas}}}=0.4{0}_{-0.09}^{+0.10} ), consistent with the red rest-frame UV slope inferred for GOODSN-100182 ( β = −0.50 ± 0.09). The star formation rate based on dust-corrected H α emission is \mathrm{log}(\mathrm{SFR(H}\alpha )/{M}_{\odot }\,{\mathrm{yr}}^{-1})=2.0{2}_{-0.14}^{+0.13} , well above the z ∼ 7 star-forming main sequence in terms of specific star formation rate. Strikingly, the ratio of [N ii ] λ 6583/H α emission suggests almost solar metallicity, as does the ratio ([O iii ] λ 5007/H β )/([N ii ] λ 6583/H α ) and the detection of the faint [Fe ii ] λ 4360 emission feature. Overall, the excitation and ionization properties of GOODSN-100182 more closely resemble those of typical star-forming galaxies at z ∼ 2–3 rather than z ∼ 7. Based on public spectroscopy of the GOODS-N field, we find that GOODSN-100182 resides within a significant galaxy overdensity, and is accompanied by a spectroscopically confirmed neighbor galaxy. GOODSN-100182 demonstrates the existence of mature, chemically enriched galaxies within the first billion years of cosmic time, whose properties must be explained by galaxy formation models.}, archive = {J_ApJ}, author = {Alice E. Shapley and Ryan L. Sanders and Michael W. Topping and Naveen A. Reddy and Anthony J. Pahl and Pascal A. Oesch and Danielle A. Berg and Rychard J. Bouwens and Gabriel Brammer and Adam C. Carnall and Fergus Cullen and Romeel Davé and James S. Dunlop and Richard S. Ellis and N. M. Förster Schreiber and Steven R. Furlanetto and Karl Glazebrook and Garth D. Illingworth and Tucker Jones and Mariska Kriek and Derek J. McLeod and Ross J. McLure and Desika Narayanan and Max Pettini and Daniel Schaerer and Daniel P. Stark and Charles C. Steidel and Mengtao Tang and Leonardo Clarke and Callum T. Donnan and Emily Kehoe}, doi = {10.3847/1538-4357/adaf98}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {167}, shortjournal = {The Astrophys. J.}, title = {The AURORA survey: An extraordinarily mature, star-forming galaxy at z ∼ 7}, volume = {981}, year = {2025}, }
• (2025). A scalable gaussian process approach to shear mapping with MuyGPs. ApJ, 981(2), 166. (www)

  @article{ , abstract = {Analysis of cosmic shear is an integral part of understanding structure growth across cosmic time, which in turn provides us with information about the nature of dark energy. Conventional methods generate shear maps from which we can infer the matter distribution in the universe. Current methods (e.g., Kaiser–Squires inversion) for generating these maps, however, are tricky to implement and can introduce bias. Recent alternatives construct a spatial process prior for the lensing potential, which allows for inference of the convergence and shear parameters given lensing shear measurements. Realizing these spatial processes, however, scales cubically in the number of observations—an unacceptable expense as near-term surveys expect billions of correlated measurements. Therefore, we present a linearly scaling shear map construction alternative using a scalable Gaussian process prior called MuyGPs. MuyGPs avoids cubic scaling by conditioning interpolation on only nearest neighbors and fits hyperparameters using batched leave-one-out cross-validation. This work is the first step toward a full, scalable mass mapping method. We work in a simplified regime where we validate our method by interpolating and analyzing maps given noisy point-estimate data from all three shear fields, taken from a suite of N -body ray-tracing simulations. We also show that we can perform these operations at the scale of billions of galaxies on high-performance computing platforms.}, archive = {J_ApJ}, author = {Gregory Sallaberry and Benjamin W. Priest and Robert Armstrong and Michael Schneider and Amanda Muyskens and Trevor Steil and Keita Iwabuchi}, doi = {10.3847/1538-4357/adb0b7}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {166}, shortjournal = {The Astrophys. J.}, title = {A scalable gaussian process approach to shear mapping with MuyGPs}, volume = {981}, year = {2025}, }
• (2025). Survival of the fittest: Testing superradiance termination with simulated binary black hole statistics. ApJ, 981(2), 165. (www)

  @article{ , abstract = {The superradiance instability of rotating black holes (BHs) leads to the formation of an ultralight boson cloud with distinctive observational signatures, making BHs an effective probe of ultralight bosons. However, around BHs in a binary system, the superradiance effect of such clouds can be terminated by tidal perturbations from the companion, leading to cloud depletion. In this study, we focus on the superradiance of a scalar boson, and perform the first analysis of the impact of this termination effect on superradiant BH binaries, which are realistically modeled after their statistics in our Galaxy. Working with a data set of approximately 10 7 BH binaries simulated using the Stellar Evolution for N -body population synthesis code, we identify the superradiant candidates and those that manage to survive the termination effect. We then calculate the cloud survival rate for various boson masses and BH spin models. Our findings reveal that the l = m = 1 cloud modes are generally stable against termination, whereas the l = m = 2 modes can be significantly affected, with survival rates dropping below 10% for boson masses below approximately 0.5 × 10 −12 eV. In addition, our analysis indicates that clouds that overcome termination typically exhibit a higher superradiant growth rate and therefore a higher detectability.}, archive = {J_ApJ}, author = {Hui-Yu Zhu and Xi Tong and Giorgio Manzoni and Yanjiao Ma}, doi = {10.3847/1538-4357/adb1db}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {165}, shortjournal = {The Astrophys. J.}, title = {Survival of the fittest: Testing superradiance termination with simulated binary black hole statistics}, volume = {981}, year = {2025}, }
• (2025). Can the dynamo of spiral-arm galaxies be explained by anisotropic conductivity?. ApJ, 981(2), 164. (www)

  @article{ , abstract = {The possibility of generating a magnetic field by a dynamo effect with anisotropic electrical conductivity rather than turbulent flow has been demonstrated theoretically and experimentally. If the electrical conductivity is anisotropic, the electrical currents will flow preferentially in certain directions rather than others, and a simple differential rotation will suffice to generate a magnetic field. In a galaxy with spiral arms, it is reasonable to assume that the electrical conductivity will be twice as large along the arms than in the perpendicular direction, suggesting the possibility of an anisotropic dynamo. However, a further geometrical criterion must be satisfied to obtain a dynamo. It is given by {{\rm{\Omega }}}^{{\prime} }\cdot \sin p\gt 0 , where p is the pitch angle of the spiral arms, with p\in [-\frac{\pi }{2},\frac{\pi }{2}] , and {{\rm{\Omega }}}^{{\prime} } is the radial shear of the angular velocity. We find that the usual spiral-arm galaxies, which satisfy | {{\rm{\Omega }}}^{{\prime} }| \lt 0 , do not satisfy this dynamo condition because they have trailing arms instead of leading arms. Even galaxy NGC 4622, which has both trailing and leading arms, does not satisfy this dynamo condition either. This is confirmed by numerical simulations of the induction equation. Thus, for all spiral-arm galaxies known to date, the anisotropy of the spiral arms cannot explain the existence of galactic magnetic fields until further notice.}, archive = {J_ApJ}, author = {Paul Gomez and Franck Plunian and Thierry Alboussière}, doi = {10.3847/1538-4357/adb1e2}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {164}, shortjournal = {The Astrophys. J.}, title = {Can the dynamo of spiral-arm galaxies be explained by anisotropic conductivity?}, volume = {981}, year = {2025}, }
• (2025). Simulation of the tianwen-4 mission contribution to jupiter gravity field improvement. ApJ, 981(2), 163. (www)

  @article{ , abstract = {This study comprehensively evaluates the impact of the expected Chinese Tianwen-4 mission, in conjunction with the existing data from the Juno mission, on enhancing the understanding of Jupiter's gravity field. Integrating simulated data from both missions. The methodology incorporates detailed simulations of Tianwen-4's orbit, assessing its influence on Jupiter's gravity field estimations across various orbital inclinations. It also explores the integration of multimission tracking data, combining simulated Juno and Tianwen-4 data. In addition to the static gravity coefficient, the analysis extends to include the tidal effect k nm , which quantifies the tidal response of Jupiter's gravity field to forcing it by the Galilean satellites. The results indicate clear potential improvements in the precision of the gravity field models compared to those derived from the Juno mission alone, particularly in the lower degree harmonics, where accuracy improves by an average factor of 20.08 in the first 12°, gradually decreasing to 2.46, with an overall enhancement of 7.43. These enhancements underscore the value of integrating data from multiple missions, which provides a more nuanced understanding of Jupiter's gravitational properties. Improving the gravity field model is essential for gaining deeper insights into Jupiter's internal structure and dynamics, which ultimately enhances our understanding of giant planets and their formation. Accurate gravity models are crucial for interpreting a planet's physical and chemical properties, leading to better comprehension of planetary systems.}, archive = {J_ApJ}, author = {Zohaib Afzal and Jianguo Yan and Dominic Dirkx and Yong Huang and Zhen Wang and Zeeshan Haider and Jean-Pierre Barriot}, doi = {10.3847/1538-4357/adb1e8}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {163}, shortjournal = {The Astrophys. J.}, title = {Simulation of the tianwen-4 mission contribution to jupiter gravity field improvement}, volume = {981}, year = {2025}, }
• (2025). Simulating ULXs and blazars as GRMHD accretion flows around a black hole. ApJ, 981(2), 162. (www)

  @article{ , abstract = {General relativistic magnetohydrodynamic (GRMHD) simulations have been instrumental in our understanding of high-energy astrophysical phenomena over the past two decades. Their robustness and modularity make them a great tool for understanding the dynamics of various astrophysical objects. In this paper, we have used GRMHD simulations to understand the accretion flows of ultraluminous X-ray sources (ULXs) and blazars. ULXs are enigmatic sources that exhibit very high luminosities (super-Eddington for stellar mass black holes) even in their low-hard state. Numerical steady-state calculations have shown that this behavior can be explained by considering ULXs to be highly magnetized advective accretion sources around stellar-mass black holes. Our simulation confirms that such an accretion flow can indeed produce the high luminosities observed in ULXs. Further to continue toward the supermassive black holes, we have also modeled blazars and have used our simulation results to explain the apparent dichotomy in the two blazar classes: flat spectrum radio quasars (FSRQs) and BL Lacertae (BL Lacs). Our results show that FSRQ and BL Lacs show different spectral characteristics due to a difference in their magnetic field characteristics. The different categories of FSRQs and BL Lacs have also been explained by the interplay between the spin, magnetic field, and accretion rate of the central supermassive black hole.}, archive = {J_ApJ}, author = {Mayank Pathak and Banibrata Mukhopadhyay}, doi = {10.3847/1538-4357/adb286}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {162}, shortjournal = {The Astrophys. J.}, title = {Simulating ULXs and blazars as GRMHD accretion flows around a black hole}, volume = {981}, year = {2025}, }
• (2025). The emergence of the star formation main sequence with redshift unfolded by JWST. ApJ, 981(2), 161. (www)

  @article{ , abstract = {We investigate the correlation between stellar mass ( M ⋆ ) and star formation rate (SFR) across the stellar mass range {\mathrm{log}}_{10}({M}_{\star }/{M}_{\odot })\approx 6-11 . We consider almost 50,000 star-forming galaxies at z ≈ 3–7, leveraging data from COSMOS/SMUVS, JADES/GOODS-S, and MIDIS/XDF. This is the first study spanning such a wide M ⋆ range without relying on gravitational lensing effects. We locate our galaxies on the SFR– M ⋆ plane to assess how the location of galaxies in the star formation main sequence (MS) and starburst (SB) region evolves with M ⋆ and redshift. We find that the two star-forming modes tend to converge at {\mathrm{log}}_{10}({M}_{\star }/{M}_{\odot })\lt 7 , with all galaxies found in the SB mode. However, deeper observations will be instrumental for reaching lower SFRs and M ⋆ to further validate this scenario. By dissecting our galaxy sample in M ⋆ and redshift, we show that the emergence of the star formation MS is M ⋆ dependent: while in galaxies with {\mathrm{log}}_{10}({M}_{\star }/{M}_{\odot })\gt 9 the MS is already well in place at z = 5–7, for galaxies with {\mathrm{log}}_{10}({M}_{\star }/{M}_{\odot })\approx 7-8 it only becomes significant at z < 4. Overall, our results are in line with previous findings that the SB mode dominates among low stellar-mass galaxies. The earlier emergence of the MS for massive galaxies is consistent with galaxy downsizing.}, archive = {J_ApJ}, author = {P. Rinaldi and R. Navarro-Carrera and K. I. Caputi and E. Iani and G. Östlin and L. Colina and S. Alberts and J. Álvarez-Márquez and M. Annunziatella and L. Boogaard and L. Costantin and J. Hjorth and D. Langeroodi and J. Melinder and T. Moutard and F. Walter}, doi = {10.3847/1538-4357/adb309}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {161}, shortjournal = {The Astrophys. J.}, title = {The emergence of the star formation main sequence with redshift unfolded by JWST}, volume = {981}, year = {2025}, }
• (2025). Probing conditions for strong clumping by the streaming instability: Small dust grains and low dust-to-gas density ratio. ApJ, 981(2), 160. (www)

  @article{ , abstract = {The streaming instability (SI) is a leading mechanism for concentrating solid particles into regions dense enough to form planetesimals. Its efficiency in clumping particles depends primarily on the dimensionless stopping time ( τ s , a proxy for particle size) and dust-to-gas surface density ratio ( Z ). Previous simulations identified a critical Z ( Z crit ) above which strong clumping occurs, where particle densities exceed the Hill density (thus satisfying a condition for gravitational collapse), over a wide range of τ s . These works found that, for τ s ≤ 0.01, Z crit was above the interstellar medium value (∼0.01). In this work, we reexamine the clumping threshold using 2D axisymmetric, stratified simulations at high resolution and with relatively large (compared to many previous simulations) domain sizes. Our main results are as follows: First, when τ s = 0.01, strong clumping occurs even at Z ≲ 0.01, lower than Z crit found in all previous studies. Consequently, we revise a previously published fit to the Z crit curve to account for this updated Z crit . Second, higher resolution results in a thicker dust layer, which may result from other instabilities manifesting, such as the vertically shearing SI. Third, despite this thicker layer, higher resolution can lead to strong clumping even with a lower midplane dust-to-gas density ratios (which results from the thicker particle layer) so long as Z ≳ Z crit . Our results demonstrate the efficiency of the SI in clumping small particles at Z ∼ 0.01, which is a significant refinement of the conditions for planetesimal formation by the SI.}, archive = {J_ApJ}, author = {Jeonghoon Lim and Jacob B. Simon and Rixin Li and Daniel Carrera and Stanley A. Baronett and Andrew N. Youdin and Wladimir Lyra and Chao-Chin Yang}, doi = {10.3847/1538-4357/adb311}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {160}, shortjournal = {The Astrophys. J.}, title = {Probing conditions for strong clumping by the streaming instability: Small dust grains and low dust-to-gas density ratio}, volume = {981}, year = {2025}, }
• (2025). Search for neutrino doublets and triplets using 11.4 yr of IceCube data. ApJ, 981(2), 159. (www)

  @article{ , abstract = {We report a search for high-energy astrophysical neutrino multiplets, detections of multiple neutrino clusters in the same direction within 30 days, based on an analysis of 11.4 yr of IceCube data. A new search method optimized for transient neutrino emission with a monthly timescale is employed, providing a higher sensitivity to neutrino fluxes. This result is sensitive to neutrino transient emission, reaching per-flavor flux of approximately 1{0}^{-10}\,\mathrm{erg}\,{\mathrm{cm}}^{-2}\,{{\rm{s}}}^{-1} from the Northern Sky in the energy range E ≳ 50 TeV. The number of doublets and triplets identified in this search is compatible with the atmospheric background hypothesis, which leads us to set limits on the nature of neutrino transient sources with emission timescales of one month.}, archive = {J_ApJ}, author = {R. Abbasi and M. Ackermann and J. Adams and S. K. Agarwalla and J. A. Aguilar and M. Ahlers and J.M. Alameddine and N. M. Amin and K. Andeen and C. Argüelles and Y. Ashida and S. Athanasiadou and S. N. Axani and R. Babu and X. Bai and A. Balagopal V. and M. Baricevic and S. W. Barwick and S. Bash and V. Basu and R. Bay and J. J. Beatty and J. Becker Tjus and J. Beise and C. Bellenghi and S. BenZvi and D. Berley and E. Bernardini and D. Z. Besson and E. Blaufuss and L. Bloom and S. Blot and F. Bontempo and J. Y. Book Motzkin and C. Boscolo Meneguolo and S. Böser and O. Botner and J. Böttcher and J. Braun and B. Brinson and Z. Brisson-Tsavoussis and J. Brostean-Kaiser and L. Brusa and R. T. Burley and D. Butterfield and M. A. Campana and I. Caracas and K. Carloni and J. Carpio and S. Chattopadhyay and N. Chau and Z. Chen and D. Chirkin and S. Choi and B. A. Clark and A. Coleman and P. Coleman and G. H. Collin and A. Connolly and J. M. Conrad and R. Corley and D. F. Cowen and C. De Clercq and J. J. DeLaunay and D. Delgado and S. Deng and A. Desai and P. Desiati and K. D. de Vries and G. de Wasseige and T. DeYoung and A. Diaz and J. C. Díaz-Vélez and P. Dierichs and M. Dittmer and A. Domi and L. Draper and H. Dujmovic and D. Durnford and K. Dutta and M. A. DuVernois and T. Ehrhardt and L. Eidenschink and A. Eimer and P. Eller and E. Ellinger and S. El Mentawi and D. Elsässer and R. Engel and H. Erpenbeck and W. Esmail and J. Evans and P. A. Evenson and K. L. Fan and K. Fang and K. Farrag and A. R. Fazely and A. Fedynitch and N. Feigl and S. Fiedlschuster and C. Finley and L. Fischer and D. Fox and A. Franckowiak and S. Fukami and P. Fürst and J. Gallagher and E. Ganster and A. Garcia and M. Garcia and G. Garg and E. Genton and L. Gerhardt and A. Ghadimi and C. Girard-Carillo and C. Glaser and T. Glüsenkamp and J. G. Gonzalez and S. Goswami and A. Granados and D. Grant and S. J. Gray and S. Griffin and S. Griswold and K. M. Groth and D. Guevel and C. Günther and P. Gutjahr and C. Ha and C. Haack and A. Hallgren and L. Halve and F. Halzen and L. Hamacher and H. Hamdaoui and M. Ha Minh and M. Handt and K. Hanson and J. Hardin and A. A. Harnisch and P. Hatch and A. Haungs and J. Häussler and K. Helbing and J. Hellrung and J. Hermannsgabner and L. Heuermann and N. Heyer and S. Hickford and A. Hidvegi and C. Hill and G. C. Hill and R. Hmaid and K. D. Hoffman and S. Hori and K. Hoshina and M. Hostert and W. Hou and T. Huber and K. Hultqvist and M. Hünnefeld and R. Hussain and K. Hymon and A. Ishihara and W. Iwakiri and M. Jacquart and S. Jain and O. Janik and M. Jansson and M. Jeong and M. Jin and B. J. P. Jones and N. Kamp and D. Kang and W. Kang and X. Kang and A. Kappes and D. Kappesser and L. Kardum and T. Karg and M. Karl and A. Karle and A. Katil and U. Katz and M. Kauer and J. L. Kelley and M. Khanal and A. Khatee Zathul and A. Kheirandish and J. Kiryluk and S. R. Klein and Y. Kobayashi and A. Kochocki and R. Koirala and H. Kolanoski and T. Kontrimas and L. Köpke and C. Kopper and D. J. Koskinen and P. Koundal and M. Kowalski and T. Kozynets and N. Krieger and J. Krishnamoorthi and T. Krishnan and K. Kruiswijk and E. Krupczak and A. Kumar and E. Kun and N. Kurahashi and N. Lad and C. Lagunas Gualda and M. Lamoureux and M. J. Larson and F. Lauber and J. P. Lazar and K. Leonard DeHolton and A. Leszczyńska and J. Liao and M. Lincetto and Y. T. Liu and M. Liubarska and C. Love and L. Lu and F. Lucarelli and W. Luszczak and Y. Lyu and J. Madsen and E. Magnus and K. B. M. Mahn and Y. Makino and E. Manao and S. Mancina and A. Mand and W. Marie Sainte and I. C. Mariş and S. Marka and Z. Marka and M. Marsee and I. Martinez-Soler and R. Maruyama and F. Mayhew and F. McNally and J. V. Mead and K. Meagher and S. Mechbal and A. Medina and M. Meier and Y. Merckx and L. Merten and J. Mitchell and T. Montaruli and R. W. Moore and Y. Morii and R. Morse and M. Moulai and T. Mukherjee and R. Naab and M. Nakos and U. Naumann and J. Necker and A. Negi and L. Neste and M. Neumann and H. Niederhausen and M. U. Nisa and K. Noda and A. Noell and A. Novikov and A. Obertacke Pollmann and V. O’Dell and A. Olivas and R. Orsoe and J. Osborn and E. O’Sullivan and V. Palusova and H. Pandya and N. Park and G. K. Parker and V. Parrish and E. N. Paudel and L. Paul and C. Pérez de los Heros and T. Pernice and J. Peterson and A. Pizzuto and M. Plum and A. Pontén and Y. Popovych and M. Prado Rodriguez and B. Pries and R. Procter-Murphy and G. T. Przybylski and L. Pyras and C. Raab and J. Rack-Helleis and N. Rad and M. Ravn and K. Rawlins and Z. Rechav and A. Rehman and E. Resconi and S. Reusch and W. Rhode and B. Riedel and A. Rifaie and E. J. Roberts and S. Robertson and S. Rodan and M. Rongen and A. Rosted and C. Rott and T. Ruhe and L. Ruohan and D. Ryckbosch and I. Safa and J. Saffer and D. Salazar-Gallegos and P. Sampathkumar and A. Sandrock and M. Santander and S. Sarkar and J. Savelberg and P. Savina and P. Schaile and M. Schaufel and H. Schieler and S. Schindler and L. Schlickmann and B. Schlüter and F. Schlüter and N. Schmeisser and T. Schmidt and J. Schneider and F. G. Schröder and L. Schumacher and S. Schwirn and S. Sclafani and D. Seckel and L. Seen and M. Seikh and M. Seo and S. Seunarine and P. Sevle Myhr and R. Shah and S. Shefali and N. Shimizu and M. Silva and B. Skrzypek and B. Smithers and R. Snihur and J. Soedingrekso and A. Søgaard and D. Soldin and P. Soldin and G. Sommani and C. Spannfellner and G. M. Spiczak and C. Spiering and J. Stachurska and M. Stamatikos and T. Stanev and T. Stezelberger and T. Stürwald and T. Stuttard and G. W. Sullivan and I. Taboada and S. Ter-Antonyan and A. Terliuk and M. Thiesmeyer and W. G. Thompson and J. Thwaites and S. Tilav and K. Tollefson and C. Tönnis and S. Toscano and D. Tosi and A. Trettin and M. A. Unland Elorrieta and A. K. Upadhyay and K. Upshaw and A. Vaidyanathan and N. Valtonen-Mattila and J. Vandenbroucke and N. van Eijndhoven and D. Vannerom and J. van Santen and J. Vara and F. Varsi and J. Veitch-Michaelis and M. Venugopal and M. Vereecken and S. Vergara Carrasco and S. Verpoest and D. Veske and A. Vijai and C. Walck and A. Wang and C. Weaver and P. Weigel and A. Weindl and J. Weldert and A. Y. Wen and C. Wendt and J. Werthebach and M. Weyrauch and N. Whitehorn and C. H. Wiebusch and D. R. Williams and L. Witthaus and M. Wolf and G. Wrede and X. W. Xu and J. P. Yanez and E. Yildizci and S. Yoshida and R. Young and F. Yu and S. Yu and T. Yuan and A. Zegarelli and S. Zhang and Z. Zhang and P. Zhelnin and P. Zilberman and M. Zimmerman and IceCube Collaboration}, doi = {10.3847/1538-4357/adb312}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {159}, shortjournal = {The Astrophys. J.}, title = {Search for neutrino doublets and triplets using 11.4 yr of IceCube data}, volume = {981}, year = {2025}, }
• (2025). Velocity structure and molecular formation in the polaris molecular cloud. ApJ, 981(2), 158. (www)

  @article{ , abstract = {We present a wide-field (60^{\prime} \times 30^{\prime} ) study of a dense region within the Polaris Flare using 12 CO, 13 CO, and C 18 O ( J = 1–0) observations at 15'' resolution, obtained with the Nobeyama 45 m Radio Telescope. The analysis reveals molecular gas formation occurring at column densities up to ∼10 21 cm −2 , evidenced by an anticorrelation between H i and CO distributions, indicating active atomic-to-molecular gas conversion. We found a threshold column density for molecular formation at ∼5 × 10 20 cm −2 , which is common among more evolved molecular clouds. The CO-to-H 2 conversion factor, X CO , was found to be 0.7 × 10 20 H 2 cm −2 (K km s −1 ) −1 , lower than the solar neighborhood average. Our chemical models estimate the cloud's age to be ∼​​​​​​10 5 –10 6 yr, suggesting an early stage of molecular cloud evolution. This interpretation is consistent with the observed low X CO factor. While virial analysis suggests that the entire cloud is gravitationally unbound, we identified several filamentary structures extending from the main cloud body. These filaments show systematic velocity gradients of 0.5–1.5 km s −1 pc −1 , and analysis of the velocities shows that the molecular gas within them is falling toward the main cloud body, following a freefall model. This suggests ongoing mass accumulation processes through the filaments, demonstrating that gravitational processes can be important even at column densities of ∼10 21 cm −2 .}, archive = {J_ApJ}, author = {Tomomi Shimoikura and Kazuhito Dobashi and Fumitaka Nakamura and Kotomi Taniguchi}, doi = {10.3847/1538-4357/adb418}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {158}, shortjournal = {The Astrophys. J.}, title = {Velocity structure and molecular formation in the polaris molecular cloud}, volume = {981}, year = {2025}, }
• (2025). Deep learning for active region classification: A systematic study from convolutional neural networks to vision transformers. ApJ, 981(2), 157. (www)

  @article{ , abstract = {Solar active regions can significantly disrupt the Sun–Earth space environment, leading to severe space weather events such as solar flares or coronal mass ejections. Consequently, the automatic classification of active region groups is a crucial starting point for accurately and promptly predicting solar activity. This study presents our application of deep learning techniques to classify active region cutouts based on the Mount Wilson classification scheme. We explore the latest advantages in image classification architectures, ranging from convolutional neural networks to vision transformers, alongside modern training procedures, including on-the-fly data augmentations and transfer learning. We aim at evaluating the respective strengths and limitations of different neural network architectures in classifying solar active region cutouts. We observed that combining magnetogram and continuum image types enhances model performance by leveraging complementary features from diverse inputs. When considering only magnetograms, data-efficient image transformers achieve the best performance, suggesting that these models can better capture the spatial complexity of magnetograms. Models trained exclusively on continuum images exhibit overall lower performance, suggesting that continuum images, due to their more homogeneous nature, offer less spatial variability.}, archive = {J_ApJ}, author = {Edoardo Legnaro and Sabrina Guastavino and Michele Piana and Anna Maria Massone}, doi = {10.3847/1538-4357/adb41a}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {157}, shortjournal = {The Astrophys. J.}, title = {Deep learning for active region classification: A systematic study from convolutional neural networks to vision transformers}, volume = {981}, year = {2025}, }
• (2025). Galactic structure dependence of Cloud–Cloud-collision-driven star formation in the barred galaxy NGC 3627. ApJ, 981(2), 156. (www)

  @article{ , abstract = {While cloud–cloud collisions (CCCs) have been proposed as a mechanism for triggering massive star formation, it is suggested that higher collision velocities ( v col ) and lower giant molecular cloud (GMC) mass ( M GMC ) and/or density (Σ GMC ) tend to suppress star formation. In this study, we choose the nearby barred galaxy NGC 3627 to examine the star formation rate and star formation efficiency (SFE) of a colliding GMC ( {m}_{{\rm{CCC}}}^{\star } and CCC ) and explore the connections between {m}_{{\rm{CCC}}}^{\star } and CCC , M GMC (Σ GMC ) and v col , and galactic structures (disk, bar, and bar end). Using Atacama Large Millimeter/submillimeter Array CO (2–1) data (60 pc resolution), we estimated v col within 500 pc apertures, based on line-of-sight GMC velocities, assuming random motion in a two-dimensional plane. We extracted apertures where at least 0.1 collisions occur per 1 Myr, identifying them as regions dominated by CCC-driven star formation, and then calculated {m}_{{\rm{CCC}}}^{\star } and CCC using attenuation-corrected H α data from MUSE on the Very Large Telescope. We found that both {m}_{{\rm{CCC}}}^{\star } and CCC are lower in the bar (median values: 10 3.84 M ⊙ and 0.18%) and higher in the bar end (10 4.89 M ⊙ and 1.10%) compared to the disk (10 4.28 M ⊙ and 0.75%). Furthermore, we found that structural differences within the parameter space of v col and M GMC (Σ GMC ), with higher M GMC (Σ GMC ) in the bar end and higher v col in the bar compared to the disk, lead to higher star formation activity in the bar end and lower activity in the bar. Our results support the scenario in which variations in CCC properties across different galactic structures can explain the observed differences in SFE on a kiloparsec scale within a disk galaxy.}, archive = {J_ApJ}, author = {Fumiya Maeda and Kouji Ohta and Fumi Egusa and Yusuke Fujimoto and Masato I. N. Kobayashi and Shin Inoue and Asao Habe}, doi = {10.3847/1538-4357/adb41e}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {156}, shortjournal = {The Astrophys. J.}, title = {Galactic structure dependence of Cloud–Cloud-collision-driven star formation in the barred galaxy NGC 3627}, volume = {981}, year = {2025}, }
• (2025). A study of abundance patterns in the sextans and sculptor dwarf spheroidal galaxies. ApJ, 981(2), 155. (www)

  @article{ , abstract = {In this work, we employ a multicomponent decomposition model to study the Sextans and Sculptor dwarf spheroidal galaxies, which have distinct evolutionary histories. Sextans exhibits massive stars dominating in the early stages of its evolution and a lower contribution from type Ia supernovae (SNe Ia). With increasing metallicity, the evolution of massive stars in Sextans shows two turning points, at [Fe/H] ∼ −2.8 and [Fe/H] ∼ −2.0, indicating episodes of accretion events and galactic winds during its evolution. In the late stages, influenced by galactic winds, the contribution from massive stars ceases, and SNe Ia become the dominant evolutionary process. Sculptor exhibits contributions from the main r -process, early very massive stars, massive stars, SNe Ia, and asymptotic giant branch (AGB) stars. In its early stages, the contributions from early very massive stars and massive stars are dominant, while the contribution from SNe Ia is low. Around [Fe/H] ∼ −2, the contribution from early very massive stars starts to decline, while the contributions from SNe Ia and massive stars continue to increase. At [Fe/H] ∼ −1.7, the contribution from massive stars gradually decreases and approaches the level of the solar neighborhood, while the contribution from AGB stars continues to rise with increasing metallicity. Both dwarf galaxies exhibit characteristic features of similar initial mass functions, but the Sextans dwarf galaxy exhibits a high-mass cutoff, while the Sculptor dwarf galaxy does not. Additionally, through decomposition, we can analyze the contributions of different astrophysical processes to [ α /Fe] versus [Fe/H], [iron-group/Fe] versus [Fe/H], and [neutron-capture/Fe] versus [Fe/H].}, archive = {J_ApJ}, author = {Shuaishuai Yang and Shichao Zhang and Lu Zhang and Hongjie Li}, doi = {10.3847/1538-4357/adb57c}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {155}, shortjournal = {The Astrophys. J.}, title = {A study of abundance patterns in the sextans and sculptor dwarf spheroidal galaxies}, volume = {981}, year = {2025}, }
• (2025). The starburst acceleration of high-velocity clouds in the galactic center. ApJ, 981(2), 154. (www)

  @article{ , abstract = {High-velocity clouds (HVCs) in the Galactic center have garnered significant attention due to their mysterious formation, potentially linked to starburst events or supermassive black hole activity in the region. However, it remains challenging to explain the observed column density and velocity distribution of HVCs. The discovery of high-velocity molecular clouds, which are denser and more massive, adds to this complexity. To address this, we conduct three-dimensional numerical simulations to explore the origin and magnetohydrodynamic evolution of HVCs in the context of a starburst in the Galactic center. By incorporating magnetic fields and an initial tangential velocity for the clouds, our simulation results align with the observed properties of HVCs, supporting the notion that these clouds can originate from a starburst process. In addition, ∼5% of the total mass of initial clouds can survive after 3.5 Myr; as a result, the following star formation will be more efficient than a feedback process that destroys all cool clouds.}, archive = {J_ApJ}, author = {Mengfei Zhang and Miao Li and Peixin Zhu}, doi = {10.3847/1538-4357/adb619}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {154}, shortjournal = {The Astrophys. J.}, title = {The starburst acceleration of high-velocity clouds in the galactic center}, volume = {981}, year = {2025}, }
• (2025). The JWST resolved stellar populations early release science program. VIII. the spatially resolved star formation history of WLM. ApJ, 981(2), 153. (www)

  @article{ , abstract = {Radial stellar population gradients within dwarf galaxies provide a promising avenue for disentangling the drivers of galaxy evolution, including environment. Within the Local Volume, radial stellar age gradient slopes correlate with interaction history, contrary to model predictions, so dwarfs that are isolated provide a critical control sample. We measure radial stellar age gradients in the relatively isolated gas-rich dwarf irregular Wolf–Lundmark–Melotte Galaxy (WLM), combining JWST NIRCam and NIRISS imaging with six archival Hubble Space Telescope fields over semimajor axis equivalent distances of 0 ≲ R SMA ≲ 4 kpc (≲3 R hl ). Fitting lifetime star formation histories to resolved color–magnitude diagrams, radial age gradients are quantified using τ 90 and τ 50 , the lookback times to form 90% and 50% of the cumulative stellar mass. We find that globally, the outskirts of WLM are older on average, with ( δτ 90 , δτ 50 )/ δ R SMA = (0.82 {}_{-0.10}^{+0.10} , 1.60 {}_{-0.22}^{+0.23} ) Gyr kpc −1 (stat.), in good agreement with simulations. However, we also detect an azimuthal dependence of radial stellar age gradients, finding that stars on the leading edge of WLM (relative to its proper motion) are both younger and have a flatter age gradient compared to the trailing edge. This difference persists over 0.6 ≲ R SMA ≲ 3.2 kpc (∼0.5–2.5 R hl ) and lookback times up to ∼8 Gyr, and is robust to the assumed stellar evolutionary model. Our results are consistent with star formation triggered by ram pressure stripping from a circumgalactic and/or intergalactic medium, suggested by recent H I observations. If confirmed, processes typifying dense environments, such as ram pressure stripping, may be more relevant to the evolution of isolated galaxies than previously thought.}, archive = {J_ApJ}, author = {Roger E. Cohen and Kristen B. W. McQuinn and Alessandro Savino and Max J. B. Newman and Daniel R. Weisz and Andrew E. Dolphin and Martha L. Boyer and Matteo Correnti and Marla C. Geha and Mario Gennaro and Karoline M. Gilbert and Nitya Kallivayalil and Jack T. Warfield and Benjamin F. Williams and Alyson M. Brooks and Andrew A. Cole and Evan D. Skillman and Christopher T. Garling and Jason S. Kalirai and Jay Anderson}, doi = {10.3847/1538-4357/adb61d}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {153}, shortjournal = {The Astrophys. J.}, title = {The JWST resolved stellar populations early release science program. VIII. the spatially resolved star formation history of WLM}, volume = {981}, year = {2025}, }
• (2025). Introducing the condor array telescope. VI. discovery of extensive ionized gaseous filaments of the cosmic web in the direction of the m81 group. ApJ, 981(2), 152. (www)

  @article{ , abstract = {We used the Condor Array Telescope to obtain deep imaging observations through luminance broadband and He ii , [O iii ], He i , H α , [N ii ], and [S ii ] narrowband filters of an extended region of the M81 Group spanning ≈8 × 8 deg 2 on the sky centered near M81 and M82. Here, we report aspects of these observations that are specifically related to (1) a remarkable filament known as the "Ursa Major Arc" that stretches ≈30° across the sky roughly in the direction of Ursa Major, (2) a "giant shell of ionized gas" that stretches ≈0.8 deg across the sky located ≈0.6 deg northwest of M82, and (3) a remarkable network of ionized gaseous filaments revealed by the new Condor observations that appear to connect the arc, the shell, and various galaxies of the M81 Group and, by extension, the group itself. We measure flux ratios between the various ions to help to distinguish photoionized from shock-ionized gas, and we find that the flux ratios of the arc and shell are not indicative of shock ionization. This provides strong evidence against a previous interpretation of the arc as an interstellar shock produced by an unrecognized supernova. We suggest that all of these objects, including the arc, are associated with the M81 Group and are located at roughly the distance (≈3.6 Mpc) of M81, that the arc is an intergalactic filament, and that the objects are associated with the low-redshift cosmic web.}, archive = {J_ApJ}, author = {Kenneth M. Lanzetta and Stefan Gromoll and Michael M. Shara and David Valls-Gabaud and Frederick M. Walter and John K. Webb}, doi = {10.3847/1538-4357/ad99ad}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {152}, shortjournal = {The Astrophys. J.}, title = {Introducing the condor array telescope. VI. discovery of extensive ionized gaseous filaments of the cosmic web in the direction of the m81 group}, volume = {981}, year = {2025}, }
• (2025). A study of emission lines in carbon stars. ApJ, 981(2), 151. (www)

  @article{ , abstract = {Carbon stars are chemically peculiar stars with high carbon abundance, showing strong carbon molecule bands and rare emission lines in their spectra. This paper explores the stellar activity of carbon stars by identifying emission line features in their spectra. An outlier detection method based on morphological feature extraction and interval representation is used to identify 88 targets presenting emission lines from 3546 carbon star spectra. Of these, 55 targets present Balmer series emissions, 35 show forbidden lines ([O i ] λ 6301 Å, [O iii ], [N ii ], [S ii ], with only 2 of the 35 spectra that present forbidden lines not showing [O i ]) and only 2 objects presenting two types of emission lines, and 51 spectra showing Balmer series emissions are C-N stars. This indicates the existence of a continuous stellar wind forming shock waves around the star, suggesting the presence of mass loss or tidal effects and exchange of materials from the companion star. In addition, 23 spectra presenting [O i ] emissions are from C-H carbon stars. These are mainly concentrated in a high-Galactic-latitude region with \left|b\right|\gt 3{0}^{\circ } , where the influence of halo clusters could lead to relatively strong magnetic activity. Other objects in the Galactic disk may also show stronger magnetic activity due to the influence of a dense medium or magnetic field, rotation, and convection within stars. In addition, one spectrum shows both [O i ] and Balmer series emissions, probably caused by magnetic activity and wave shock. Another spectrum shows both Balmer series and [O iii ] emissions, presumably contaminated by an unknown nebula.}, archive = {J_ApJ}, author = {Lichan Zhou and Jianghui Cai and Haifeng Yang and Yuqing Yang and Xujun Zhao and Yaling Xun}, doi = {10.3847/1538-4357/ada159}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {151}, shortjournal = {The Astrophys. J.}, title = {A study of emission lines in carbon stars}, volume = {981}, year = {2025}, }
• (2025). Observing Rayleigh–Taylor stable and unstable accretion through a kalman filter analysis of X-ray pulsars in the small magellanic cloud. ApJ, 981(2), 150. (www)

  @article{ , abstract = {Global, three-dimensional magnetohydrodynamic simulations of Rayleigh–Taylor instabilities at the disk–magnetosphere boundary of rotating, magnetized compact stellar objects reveal that accretion occurs in three regimes: the stable regime, the chaotic unstable regime, and the ordered unstable regime. Here we track stochastic fluctuations in the pulse period P ( t ) and aperiodic X-ray luminosity L ( t ) time series of 24 accretion-powered pulsars in the Small Magellanic Cloud using an unscented Kalman filter to analyze Rossi X-ray Timing Explorer data. We measure time-resolved histories of the magnetocentrifugal fastness parameter ω ( t ) and we connect ω ( t ) with the three Rayleigh–Taylor accretion regimes. The 24 objects separate into two distinct groups, with 10 accreting in the stable regime and 14 accreting in the ordered unstable regime. None of the 24 objects except SXP 293 visit the chaotic unstable regime for sustained intervals, although several objects visit it sporadically. The Kalman filter output also reveals a positive temporal cross-correlation between ω ( t ) and the independently measured pulse amplitude A ( t ), which agrees with simulation predictions regarding the pulse-forming behavior of magnetospheric funnel flows in the three accretion regimes.}, archive = {J_ApJ}, author = {Joseph O’Leary and Andrew Melatos and Tom Kimpson and Dimitris M. Christodoulou and Nicholas J. O’Neill and Patrick M. Meyers and Sayantan Bhattacharya and Silas G.T. Laycock}, doi = {10.3847/1538-4357/adaf26}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {150}, shortjournal = {The Astrophys. J.}, title = {Observing Rayleigh–Taylor stable and unstable accretion through a kalman filter analysis of X-ray pulsars in the small magellanic cloud}, volume = {981}, year = {2025}, }
• (2025). You shall not pass! the propagation of low-/Moderate-powered jets through a turbulent interstellar medium. ApJ, 981(2), 149. (www)

  @article{ , abstract = {Feedback from black-hole-powered jets has been invoked in many cosmological simulations to regulate star formation and quench galaxies. Despite this, observational evidence of how jets might be able to affect their hosts remains scarce, especially for low-power jets in halos smaller than clusters. Recent observations of outflows around FR0 galaxies, which host compact radio-loud sources, imply that lower-power jetted active galactic nuclei (AGN) may have a significant impact on their hosts through jet interactions with the interstellar medium (ISM). Using the Arepo code, we launch jets of low and intermediate power (10 38 –10 43 erg s −1 ) within a ∼kiloparsec-scale periodic box with driven turbulence, to study how the jets propagate through a turbulent ISM. Our simulation results broadly fit into three different scenarios—jets penetrating easily through the ISM, becoming completely stalled, or, an interesting intermediate stage, jets being highly disturbed and redirected. We suggest that intermediate-power jets do not have enough ram pressure to affect the turbulent structure of the ISM and so only fill preexisting cavities. Low-power jets are able to drive outflows in a hot phase (>10 4.4 K). However, warm (∼10 4 K) ionized gas outflows appear under certain conditions. This work is part of the "Learning the Universe" collaboration, aiming to build next-generation cosmological simulations that incorporate a new prescription for AGN feedback.}, archive = {J_ApJ}, author = {Olga Borodina and Yueying Ni and Jake S. Bennett and Rainer Weinberger and Greg L. Bryan and Michaela Hirschmann and Marion Farcy and Julie Hlavacek-Larrondo and Lars Hernquist}, doi = {10.3847/1538-4357/adb016}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {149}, shortjournal = {The Astrophys. J.}, title = {You shall not pass! the propagation of low-/Moderate-powered jets through a turbulent interstellar medium}, volume = {981}, year = {2025}, }
• (2025). Ab initio quantum dynamics as a scalable solution to the exoplanet opacity challenge: A case study of CO2 in a hydrogen atmosphere. ApJ, 981(2), 148. (www)

  @article{ , abstract = {Light–matter interactions lie at the heart of our exploration of exoplanetary atmospheres. Interpreting data obtained by remote sensing is enabled by meticulous, time- and resource-consuming work aiming at deepening our understanding of such interactions (i.e., opacity models). Recently, P. Niraula et al. pointed out that due primarily to limitations on our modeling of broadening and far-wing behaviors, opacity models needed a timely update for exoplanet exploration in the JWST era, and thus argued for a scalable approach. In this proof-of-concept study, we introduce an end-to-end solution from ab initio calculations to pressure broadening, and use a perturbation framework to address the need for precision to a level of ∼10%. We focus on the CO 2 –H 2 system as CO 2 is a key absorption feature for exoplanet research (primarily in many gas giants) at ∼4.3 μ m as pressure-broadening parameters required for interpreting such observations remain sparse. We compute elastic and inelastic cross sections for the collisions of ortho-H 2 with CO 2 , in the ground vibrational state, and at the coupled-channel fully converged level. For scattering energies above ∼20 cm −1 , moderate precision intermolecular potentials are indistinguishable from high-precision ones in cross sections. Our calculations agree with the currently available measurements within 7%, i.e., well beyond the precision requirements.}, archive = {J_ApJ}, author = {Laurent Wiesenfeld and Prajwal Niraula and Julien de Wit and Nejmeddine Jaïdane and Iouli E. Gordon and Robert J. Hargreaves}, doi = {10.3847/1538-4357/adb02e}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {148}, shortjournal = {The Astrophys. J.}, title = {Ab initio quantum dynamics as a scalable solution to the exoplanet opacity challenge: A case study of CO2 in a hydrogen atmosphere}, volume = {981}, year = {2025}, }
• (2025). The evolution of molecular clouds: Turbulence-regulated global radial collapse. ApJ, 981(2), 147. (www)

  @article{ , abstract = {The star formation efficiency (SFE) measures the proportion of molecular gas converted into stars, while the star formation rate (SFR) indicates the rate at which gas is transformed into stars. Here we propose such a model in the framework of a turbulence-regulated global radial collapse in molecular clouds being in quasi-virial equilibrium, where the collapse velocity depends on the density profile and the initial mass-to-radius ratio of molecular clouds, with the collapse velocity accelerating during the collapse process. This simplified analytical model allows us to estimate a lifetime of giant molecular clouds of approximately 0.44−7.36 × 10 7 yr, and a star formation timescale of approximately 0.5–5.88 × 10 6 yr. Additionally, we can predict an SFE of approximately 1.59%, and an SFR of roughly 1.85 M ⊙ yr −1 for the Milky Way in agreement with observations.}, archive = {J_ApJ}, author = {An-Xu Luo and Hong-Li Liu and Jin-Zeng Li}, doi = {10.3847/1538-4357/adb131}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {147}, shortjournal = {The Astrophys. J.}, title = {The evolution of molecular clouds: Turbulence-regulated global radial collapse}, volume = {981}, year = {2025}, }
• (2025). The stationary point: A new method for solar wind speed measurements from a moving vantage point. ApJ, 981(2), 146. (www)

  @article{ , abstract = {The WISPR imager on Parker Solar Probe (PSP) provides a unique view of the young solar wind as it flies through solar wind structures at high speed. It is of interest to use WISPR image sequences to measure the velocity of both large features (such as coronal mass ejections) and the background, ambient wind. However, WISPR's close-up, rapidly moving perspective makes the usual methods for measuring velocities from images difficult or impossible to apply, as most apparent motion through the image is due to the motion or rotation of the imager. In this work, we propose a new method of looking for features at the "stationary point"—a direction from which some plasma parcels appear to approach the spacecraft, remaining at a constant direction in the image sequence. This direction is a function of the plasma's radial velocity, the encounter geometry, and the spacecraft velocity, allowing the former two to be inferred. We demonstrate the technique with forward-modeled images, and we apply it to WISPR observations, inferring the speed and trajectory of a particular density feature. This method promises to enable speed measurements of the young solar wind in an important acceleration region, from a close-up perspective and at latitudes well outside the PSP orbital plane. And while we present this method in a solar wind context, it is broadly applicable to any situation of a moving viewpoint traveling through an expanding cloud of features.}, archive = {J_ApJ}, author = {Samuel J. Van Kooten and Craig E. Deforest and Guillermo Stenborg and Kenny N. Kenny}, doi = {10.3847/1538-4357/adb1a5}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {146}, shortjournal = {The Astrophys. J.}, title = {The stationary point: A new method for solar wind speed measurements from a moving vantage point}, volume = {981}, year = {2025}, }
• (2025). Revision of two-temperature magnetically arrested flows onto a black hole. ApJ, 981(2), 145. (www)

  @article{ , abstract = {We revisit the radiative properties of 3D general relativistic magnetohydrodynamics (GRMHD) two-temperature magnetically arrested disk (MAD) models in which electrons are heated by a magnetic turbulent cascade. We focus on studying the model emission, whose characteristics include variability in both total intensity and linear/circular polarizations as well as rotation measures at energies around the synchrotron emission peak in millimeter waves. We find that the radiative properties of MAD models with turbulent electron heating are well converged with respect to the numerical grid resolution, which has not been demonstrated before. We compare radiation from two-temperature simulations with turbulent heating to single-temperature models with electron temperatures calculated based on the commonly used R ( β ) prescription. We find that the self-consistent two-temperature models with turbulent heating do not significantly outperform the R ( β ) models and, in practice, may be indistinguishable from the R ( β ) models. Accounting for physical effects such as radiative cooling and the nonthermal electron distribution function makes a weak impact on properties of millimeter emission. Models are scaled to Sgr A*, an accreting black hole in the center of our galaxy, and compared to the most complete observational data sets. We point out the consistencies and inconsistencies between the MAD models and observations of this source and discuss future prospects for GRMHD simulations.}, archive = {J_ApJ}, author = {M. Mościbrodzka}, doi = {10.3847/1538-4357/adb1a7}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {145}, shortjournal = {The Astrophys. J.}, title = {Revision of two-temperature magnetically arrested flows onto a black hole}, volume = {981}, year = {2025}, }
• (2025). X-ray spectra from general relativistic radiation magnetohydrodynamic simulations of thin disks. ApJ, 981(2), 144. (www)

  @article{ , abstract = {We compare X-ray emission from several general relativistic, multifrequency, radiation magnetohydrodynamic simulations of thin black hole accretion disks with different accretion rates and spins. The simulations were performed using the M 1 closure scheme, resolved with 12 frequency (energy) bins logarithmically spaced from 5 × 10 −3 to 5 × 10 3 ​​​ keV. We apply a general relativistic Monte Carlo transport code to postprocess the simulation data with greater fidelity in frequency resolution and Compton scattering treatment. Despite the relatively few energy bins and Kompaneets approximation to Compton scattering utilized in the M 1 method, we find generally good agreement between the methods. Both produce prominent thermal profiles with peaks around 2–2.5 keV, where agreement is particularly strong and representative of the soft state. Both also find weaker (lower-luminosity) thermally sourced emission extending out to 100 keV due to the hotter innermost regions of the disks. Inverse Compton scattering becomes increasingly effective at hardening spectral outputs with increasing black hole spin, and becomes the dominant mechanism for photons that escape with energies between 10 to several hundred keV. At very high rates of spin, the radiation flux in this upscattered component becomes comparable to the thermal flux, a phenomenon typically associated with intermediate states. Beyond 10 4 keV, we observe faint, free–free emission from hot, optically thin coronal regions developing near the horizon, common to both spinning and nonspinning black holes.}, archive = {J_ApJ}, author = {Nathaniel Roth and Peter Anninos and P. Chris Fragile and Derrick Pickrel}, doi = {10.3847/1538-4357/adb1c1}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {144}, shortjournal = {The Astrophys. J.}, title = {X-ray spectra from general relativistic radiation magnetohydrodynamic simulations of thin disks}, volume = {981}, year = {2025}, }
• (2025). Discovery of an RRAT-like pulsar via its single pulses in a murchison widefield array imaging survey. ApJ, 981(2), 143. (www)

  @article{ , abstract = {We report the discovery of PSR J0031–5726 in the Galactic and Extragalactic All-sky Murchison Widefield Array Extended imaging survey at a Galactic latitude of b ≈ −60 ∘ . The pulsar exhibits both sporadic, extremely bright pulses reminiscent of rotating radio transients (RRATs) as well as persistent, dimmer pulses. The bright pulses tend to arrive at later rotation phases than their dimmer counterparts and have dramatically varying polarization angle curves, such that the integrated profile appears almost completely depolarized down to the system noise level. The rotation measure of individual pulses was found to sometimes vary by up to ∼0.8 rad m −2 , but was otherwise generally consistent with its average (ionosphere-corrected) value of 10.0 ± 0.1 rad m −2 . We surmise that J0031–5726 may represent a class of pulsars that is intermediate between normal pulsars and RRATs.}, archive = {J_ApJ}, author = {Samuel J. Mcsweeney and Jared Moseley and Natasha Hurley-Walker and Garvit Grover and Csanád Horváth and Timothy J. Galvin and Bradley W. Meyers and Chia Min Tan}, doi = {10.3847/1538-4357/adb27f}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {143}, shortjournal = {The Astrophys. J.}, title = {Discovery of an RRAT-like pulsar via its single pulses in a murchison widefield array imaging survey}, volume = {981}, year = {2025}, }
• (2025). Amplifying resonant repulsion with inflated young planets, overlooked inner planets, and nonzero initial Δ. ApJ, 981(2), 142. (www)

  @article{ , abstract = {Most multiplanet systems around mature (∼5 Gyr old) host stars are nonresonant. Even the near-resonant planet pairs still display 1%–2% positive deviation from perfect period commensurabilities (Δ) near first-order mean motion resonances (MMRs). Resonant repulsion due to eccentricity tides was one of the first mechanisms proposed to explain the observed positive Δ. However, the inferred rates of tidal dissipation are often implausibly rapid (with a reduced tidal quality factor {Q}_{p}^{{\prime} }\lesssim 10 ). In this work, we attempt to amplify eccentricity tides with three previously ignored effects. (1) Planets tend to be inflated when they were younger. (2) Kepler-like planets likely form as resonant chains parked at the disk inner edge; overlooked inner planets could have contributed to tidal dissipation of the whole system. (3) Disk migration captures planets into first-order MMR with nonzero initial deviation Δ, thereby lowering the amount of dissipation needed. We show that even after accounting for all three effects, {Q}_{p}^{{\prime} } can only be amplified by about 1 order of magnitude, and still falls short of {Q}_{p}^{{\prime} } values of solar system planets. Therefore, eccentricity tides alone cannot fully explain the observed Δ distribution. Other effects such as obliquity tides, planetesimal scattering, expanding disk inner edge, disk turbulence, divergent encounters, and dynamical instabilities must have contributed to dislodging planets from first-order MMR.}, archive = {J_ApJ}, author = {Yuancheng Xu and Fei Dai}, doi = {10.3847/1538-4357/adb281}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {142}, shortjournal = {The Astrophys. J.}, title = {Amplifying resonant repulsion with inflated young planets, overlooked inner planets, and nonzero initial Δ}, volume = {981}, year = {2025}, }
• (2025). Contaminating electromagnetic transients in LISA gravitational-wave localization volumes. i. the intrinsic rates. ApJ, 981(2), 141. (www)

  @article{ , abstract = {The Laser Interferometer Space Antenna (LISA) will soon detect gravitational waves (GWs) emitted by massive black hole (MBH) mergers. Some theoretical models have predicted transient electromagnetic (EM) emission from these mergers, enabling the association of LISA GW sources with their EM counterparts via telescope follow-up. However, the number of unrelated EM transients that might contaminate telescope searches for the true transient counterparts of LISA MBH mergers is unknown. We investigate the expected numbers of unrelated EM transients that will coincide with simulated LISA localization volumes of MBH mergers as a function of the merger total mass and redshift. We find that the number of potential contaminants in LISA localization volumes drops to unity for mergers at z ≲ 0.8 and at 1 hr before coalescence. After coalescence, the parameter space corresponding to a maximum of one potential contaminant expands to z ≲ 1.5. In contrast, if the redshifts for all transients detected in LISA sky localization regions are not available, the number of potential contaminants increases by an average factor of ∼100 and never drops below unity. Overall, we expect the average number of contaminating transients in telescope follow-up of LISA MBH mergers to be nonnegligible, especially without redshift information for the detected transients. We recommend that endeavors designing follow-up strategies of LISA events should focus on (1) building large redshift catalogs for host galaxies, (2) developing robust real-time transient classification algorithms, and (3) coordinating telescope resources to obtain redshifts for candidate transient EM counterparts in a timely manner.}, archive = {J_ApJ}, author = {Weixiang Yu and John J. Ruan and Michael Eracleous and Jessie Runnoe and Daryl Haggard and Tamara Bogdanović and Aaron Stemo and Kaitlyn Szekerczes and Carolyn L. Drake and Kate E. Futrowsky and Steinn Sigurdsson}, doi = {10.3847/1538-4357/adb283}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {141}, shortjournal = {The Astrophys. J.}, title = {Contaminating electromagnetic transients in LISA gravitational-wave localization volumes. i. the intrinsic rates}, volume = {981}, year = {2025}, }
• (2025). Radial evolution of a density structure within a solar wind magnetic sector boundary. ApJ, 981(2), 140. (www)

  @article{ , abstract = {This study focuses on a radial alignment between Parker Solar Probe (PSP) and Solar Orbiter (SolO) on 2021 April 29 (during a solar minimum), when the two spacecraft were, respectively, located at ∼0.075 and ∼0.9 au from the Sun. A previous study of this alignment allowed the identification of the same density enhancement (with a timescale of ∼1.5 hr) and substructures (timescales of ∼20–30 minutes), passing first by PSP and then by SolO after a ∼138 hr propagation time in the inner heliosphere. We show here that this structure belongs to the large-scale heliospheric magnetic sector boundary. In this region, the density is dominated by radial gradients, whereas the magnetic field reversal is consistent with longitudinal gradients in the Carrington reference frame. We estimate the density structure radial size to remain of the order L R ∼ 10 6 km, while its longitudinal and latitudinal sizes are estimated to expand from L φ , θ ∼ 10 4 –10 5 km in the high solar corona to L φ , θ ∼ 10 5 –10 6 km at PSP and L φ , θ ∼ 10 6 –10 7 km at SolO. This implies a strong evolution of the structure's aspect ratio during the propagation, due to the plasma's nearly spherical expansion. The structure's shape is therefore inferred to evolve from elongated in the radial direction at ∼2–3 solar radii (high corona) to sizes of nearly the same order in all directions at PSP and then becoming elongated in the directions transverse to the radial at SolO. Measurements are not concordant with local reconnection of open solar wind field lines, so we propose that the structure has been generated through interchange reconnection near the tip of a coronal streamer.}, archive = {J_ApJ}, author = {Etienne Berriot and Pascal Démoulin and Olga Alexandrova and Arnaud Zaslavsky and Milan Maksimovic and Georgios Nicolaou}, doi = {10.3847/1538-4357/adb39a}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {140}, shortjournal = {The Astrophys. J.}, title = {Radial evolution of a density structure within a solar wind magnetic sector boundary}, volume = {981}, year = {2025}, }
• (2025). Simultaneous existence of oscillations, counterstreaming flows, and mass injections in solar quiescent prominences. ApJ, 981(2), 139. (www)

  @article{ , abstract = {Solar prominences are very spectacular structures embedded in the tenuous and hot solar corona. Counterstreaming flows, a common feature in solar quiescent prominences, have been discovered for more than 20 yr. However, the mechanism driving the counterstreaming flows is still elusive. To unveil the nature of this phenomenon, we analyzed data of a quiescent prominence observed by the New Vacuum Solar Telescope, the Interface Region Imaging Spectrograph, and the Solar Dynamical Observatory. It is found that there is a distinct longitudinal oscillation of prominence plasma along the higher part of the prominence spine in H α observations. The oscillation period is approximately 83 minutes and the amplitude is about 32 Mm. The counterstreaming flows are dominant in the middle part of the prominence spine. The velocities of the counterstreaming flows range from about 4 to 11 km s −1 . Moreover, intermittent mass flows with upward plumes from the top of the bubbles and tornado-like barbs are observed to be injected into the lower part of the prominence spine from the lower atmosphere. The velocities of these injected mass flows range from about 3 to 30 km s −1 . Some injected mass flows exhibit redshifted Doppler signals, while others exhibit blueshifted signals. Based on these high-resolution observations, it is found that different parts of the prominence spine exhibit different dynamic characteristics. These results further advance the understanding of the ubiquitous counterstreaming flows in solar quiescent prominences.}, archive = {J_ApJ}, author = {Xiaoli Yan and Zhike Xue and Jincheng Wang and Pengfei Chen and Kaifan Ji and Chun Xia and Liheng Yang and Defang Kong and Zhe Xu and Yian Zhou and Qiaoling Li}, doi = {10.3847/1538-4357/adb39e}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {139}, shortjournal = {The Astrophys. J.}, title = {Simultaneous existence of oscillations, counterstreaming flows, and mass injections in solar quiescent prominences}, volume = {981}, year = {2025}, }
• (2025). Early accretion of large amounts of solids for directly imaged exoplanets. ApJ, 981(2), 138. (www)

  @article{ , abstract = {As the number of planetary-mass objects (PMOs; ⪅13 M Jupiter ) at wider separation (⪆10 au) grows, there is emerging evidence that they form differently from their higher-mass brown dwarf counterparts. Specifically, PMOs' atmospheres are often enriched by metals and show a large dispersion of metallicity, which is usually interpreted as a sign of solid accretion. As a first step toward a population-level study of the amount and timing of solid accretion, we analyze a sample of seven directly imaged exoplanets with measured stellar and planetary chemical abundances (51 Eri b, β Pic b, HIP 65426 b, HR 8799c and e, AF Lep b, and YSES 1 c). Our analysis uses existing data of stellar and planetary atmospheric metallicities and adopts a Bayesian framework that marginalizes the probabilities of disk conditions, formation locations, planetary interior structures, and accretion physics. We show that these PMOs accrete large amounts of solids regardless of whether they form via core accretion or disk instability. On average, ⪆50 M ⊕ of solids are accreted to enrich planet atmospheres. An individual planet accretes between 23.3 and 223.2 M ⊕ of solid mass, more than 75% of which is assumed to stay in the atmosphere and increase the observed metallicity. The result implies that the solid accretion process and therefore the planet formation process likely take place at an early stage (⪅2 Myr) when large amounts of solids are available in young massive protoplanetary disks.}, archive = {J_ApJ}, author = {Ji Wang}, doi = {10.3847/1538-4357/adb42c}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {138}, shortjournal = {The Astrophys. J.}, title = {Early accretion of large amounts of solids for directly imaged exoplanets}, volume = {981}, year = {2025}, }
• (2025). Connecting dust and outflows in active galactic nuclei: The intriguing case of NGC 6860. ApJ, 981(2), 137. (www)

  @article{ , abstract = {Cosmic dust plays a crucial role in the evolution of galaxies, significantly influencing star formation and the interstellar medium. However, in active galactic nuclei (AGNs), the role and origin of dust remain poorly understood. High-resolution X-ray spectroscopy is a powerful tool for probing the properties of dust in AGN. NGC 6860, an X-ray bright type-1 quasar, is an ideal target for investigating the connection between dust and winds in AGN. It exhibits reddening and X-ray absorption by both dust and winds. By modeling high-resolution X-ray spectra from XMM-Newton and Chandra observations, we determine the properties of dust and outflows in this AGN. Our analysis finds four photoionized components, outflowing with velocities of 50–300 km s −1 . The first two are relatively highly ionized with \mathrm{log}\xi =3.4 and \mathrm{log}\xi =2.9 . The results of our photoionization modeling suggest that these two components are thermally unstable. The third component is ionized, with \mathrm{log}\xi =2.3 , and is located farther away from the central black hole. The fourth component is less ionized and is possibly located in the host galaxy. The application of dust models enables us to probe the abundance and location of the dust in NGC 6860. Our findings suggest that dust absorption and reddening originates from the extended narrow-line region and its host galaxy.}, archive = {J_ApJ}, author = {I. Psaradaki and M. Mehdipour and D. Rogantini and E. Costantini and N. Schulz and S. Zeegers and E. Caruso}, doi = {10.3847/1538-4357/adb4e9}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {137}, shortjournal = {The Astrophys. J.}, title = {Connecting dust and outflows in active galactic nuclei: The intriguing case of NGC 6860}, volume = {981}, year = {2025}, }
• (2025). What can we learn from the nitrogen abundance of high-z galaxies?. ApJ, 981(2), 136. (www)

  @article{ , abstract = {We present measurements of the gas-phase oxygen and nitrogen abundances obtained by applying the direct method to JWST NIRspec R ∼ 1000 spectroscopy for six galaxies at redshift greater than 3. Our measurements are based on rest-frame optical nitrogen [N ii ] λλ 6548,6583 lines and are complemented by six additional objects from the literature at 3 ≤ z ≤ 6. We find that 9 out of 12 objects have values of log(N/O) that are compatible with those found for low-redshift, metal-poor, dwarf galaxies and for H ii regions of more luminous local galaxies. However, 3 out of 12 objects have log(N/O) values that are overabundant compared to what is expected on the basis of their oxygen abundance. We explore a few standard scenarios to explain the observations and conclude that, within the limited statistics available to us, none of them can be definitely excluded even though we prefer dilution by pristine gas infall in between star formation bursts, as this is predicted by simulations to take place as a natural part of bursty star formation.}, archive = {J_ApJ}, author = {Massimo Stiavelli and Takahiro Morishita and Marco Chiaberge and Nicha Leethochawalit and Colin Norman and Massimo Ricotti and Guido Roberts-Borsani and Tommaso Treu and Eros Vanzella and Rosemary F. G. Wyse and Yechi Zhang and Kit Boyett}, doi = {10.3847/1538-4357/adb5f3}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {136}, shortjournal = {The Astrophys. J.}, title = {What can we learn from the nitrogen abundance of high-z galaxies?}, volume = {981}, year = {2025}, }
• (2025). RIOJA. complex dusty starbursts in a major merger b14-65666 at z = 7.15. ApJ, 981(2), 135. (www)

  @article{ , abstract = {We present JWST NIRCam imaging of B14-65666 ("Big Three Dragons"), a bright Lyman-break galaxy system ( M UV = −22.5 mag) at z = 7.15. The high angular resolution of NIRCam reveals the complex morphology of two galaxy components: galaxy E has a compact core (E-core), surrounded by diffuse, extended, rest-frame optical emission, which is likely to be tidal tails; and galaxy W has a clumpy and elongated morphology with a blue UV slope ( β UV = −2.2 ± 0.1). The flux excess, F356W − F444W, peaks at the E-core ( 1.0{5}_{-0.09}^{+0.08} mag), tracing the presence of strong [O iii ] λλ 4960,5008 emission. Atacama Large Millimeter/submillimeter Array archival data show that the bluer galaxy W is brighter in dust continua than the redder galaxy E, while the tails are bright in [O iii ] 88 μ m. The UV/optical and submillimeter spectral energy distribution (SED) fitting confirms that B14-65666 is a major merger in a starburst phase as derived from the stellar mass ratio (3:1 to 2:1) and the star formation rate, ≃1 dex higher than the star formation main sequence at the same redshift. Galaxy E is a dusty ( A V = 1.2 ± 0.1 mag) starburst with a possible high dust temperature (≥63–68 K). Galaxy W would have a low dust temperature (≤27–33 K) or patchy stellar-and-dust geometry, as suggested by the IR excess and β UV diagram. The high optical-to-far-IR [O iii ] line ratio of the E-core shows its lower gas-phase metallicity (≃0.2–0.4 Z ⊙ ) than galaxy W. These results agree with a scenario where major mergers disturb morphology and induce nuclear dusty starbursts triggered by less-enriched inflows. B14-65666 shows a picture of complex stellar buildup processes during major mergers in the epoch of reionization.}, archive = {J_ApJ}, author = {Yuma Sugahara and Javier Álvarez-Márquez and Takuya Hashimoto and Luis Colina and Akio K. Inoue and Luca Costantin and Yoshinobu Fudamoto and Ken Mawatari and Yi W. Ren and Santiago Arribas and Tom J. L. C. Bakx and Carmen Blanco-Prieto and Daniel Ceverino and Alejandro Crespo Gómez and Masato Hagimoto and Takeshi Hashigaya and Rui Marques-Chaves and Hiroshi Matsuo and Yurina Nakazato and Miguel Pereira-Santaella and Yoichi Tamura and Mitsutaka Usui and Naoki Yoshida}, doi = {10.3847/1538-4357/adb02a}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {135}, shortjournal = {The Astrophys. J.}, title = {RIOJA. complex dusty starbursts in a major merger b14-65666 at z = 7.15}, volume = {981}, year = {2025}, }
• (2025). A spectroscopic analysis of the ionizing photon production efficiency in JADES and CEERS: Implications for the ionizing photon budget. ApJ, 981(2), 134. (www)

  @article{ , abstract = {We have used a combined sample of JADES and CEERS objects in order to constrain ionizing photon production efficiency ( ξ ion ) from JWST/NIRSpec and JWST/NIRCam data. We examine 163 objects at 1.06 < z < 6.71 with significant (3 σ ) spectroscopic detections of H α and H β in order to constrain intrinsic H α luminosities corrected from nebular dust attenuation via Balmer decrements. We constrain dust-corrected UV luminosities from best-fit spectral energy distribution modeling. We find a sample median {{\rm{log}}}_{10}({\xi }_{{\rm{ion,0}}}/{{\rm{erg}}\,{\rm{Hz}}}^{-1})=25.2{9}_{-0.37}^{+0.29} , assuming f esc = 0 for the escape fraction of Lyman continuum (LyC) emission. We find significant (Spearman r s = 0.19, p = 0.01) correlation between ξ ion,0 and z , with objects at z > 4.64 having median {{\rm{log}}}_{10}({\xi }_{{\rm{ion,0}}}/{{\rm{erg}}\,{\rm{Hz}}}^{-1})=25.3{8}_{-0.38}^{+0.38} , with those below having {{\rm{log}}}_{10}({\xi }_{{\rm{ion,0}}}/{{\rm{erg}}\,{\rm{Hz}}}^{-1})=25.2{4}_{-0.33}^{+0.30} . We also find significant, positive correlations between ξ ion,0 and L UV ; W λ ([O iii ]); [O iii ] λ 5007/[O ii ] λλ 3726, 3729; and inverse correlations with metallicity. In contrast with some previous results, we find no trends between ξ ion,0 and stellar mass, stellar dust attenuation, or UV slope. Applying a multivariate fit to ξ ion,0 , z , and M UV to an empirically motivated model of reionization, and folding in f esc estimates from direct observations of the LyC at z ∼ 3 from the Keck Lyman Continuum Spectroscopic Survey, we find that the number of ionizing photons entering the IGM causes reionization to end at z ∼ 5–7.}, archive = {J_ApJ}, author = {Anthony Pahl and Michael W. Topping and Alice Shapley and Ryan Sanders and Naveen A. Reddy and Leonardo Clarke and Emily Kehoe and Trinity Bento and Gabe Brammer}, doi = {10.3847/1538-4357/adb1ab}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {134}, shortjournal = {The Astrophys. J.}, title = {A spectroscopic analysis of the ionizing photon production efficiency in JADES and CEERS: Implications for the ionizing photon budget}, volume = {981}, year = {2025}, }
• (2025). Effect of deviations from general relativity on searches for gravitational-wave microlensing and type II strong lensing. ApJ, 981(2), 133. (www)

  @article{ , abstract = {As the gravitational-wave (GW) detector network is upgraded and the sensitivity of the detectors improves, novel scientific avenues open for exploration. For example, tests of general relativity (GR) will become more accurate as smaller deviations can be probed. Additionally, the detection of lensed GWs becomes more likely. However, these new avenues could also interact with each other, and a GW event presenting deviations from GR could be mistaken for a lensed one. Here, we explore how phenomenological deviations from GR or binaries of exotic compact objects could impact those lensing searches focusing on a single event. We consider strong lensing, millilensing, and microlensing, and find that certain phenomenological deviations from GR may be mistaken for all of these types of lensing. Therefore, our study shows that future candidate lensing events would need to be carefully examined to avoid a false claim of lensing where instead a deviation from GR has been seen.}, archive = {J_ApJ}, author = {Mick Wright and Justin Janquart and Nathan K. Johnson-McDaniel}, doi = {10.3847/1538-4357/ad9d3e}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {133}, shortjournal = {The Astrophys. J.}, title = {Effect of deviations from general relativity on searches for gravitational-wave microlensing and type II strong lensing}, volume = {981}, year = {2025}, }
• (2025). SOFIA polarization spectrum of three star-forming clouds. ApJ, 981(2), 132. (www)

  @article{ , abstract = {The dust emission polarization spectrum—how the polarization percentage changes with wavelength—serves as a probe of dust grain properties in star-forming regions. In this paper, we present 89–214 μ m polarization spectrum measurements obtained from SOFIA/HAWC+ for three star-forming clouds: OMC1, M17, and W3. We find that all three clouds have an overall decreasing polarization percentage with increasing wavelength (i.e., a "falling polarization spectrum"). We use SOFIA and Herschel data to create column density and temperature maps for each cloud. We fit for the slope of the polarization spectrum at each sky position in each cloud, and using the Pearson r coefficient, we probe each cloud for possible correlations of slope with column density and slope with temperature. We also create plots of slope versus column density and slope versus temperature for each cloud. For the case of OMC1, our results are consistent with those presented by J. Michail et al., who carried out a similar analysis for that cloud. Our plots of polarization spectrum slope versus column density reveal that for each cloud there exists a critical column density below which a falling polarization spectrum is not observed. For these more diffuse sight lines, the polarization spectrum is instead flat or slightly rising. This finding is consistent with a hypothesis presented 25 yr ago in a paper led by R. Hildebrand based on Kuiper Airborne Observatory data. This hypothesis is that regions shielded from near-IR radiation are required to produce a sharply falling polarization spectrum.}, archive = {J_ApJ}, author = {Erin G. Cox and Giles Novak and David T. Chuss and Dennis Lee and Marc Berthoud and Kaitlyn Karpovich and Joseph M. Michail and Zhi-Yun Li and Peter C. Ashton}, doi = {10.3847/1538-4357/ada447}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {132}, shortjournal = {The Astrophys. J.}, title = {SOFIA polarization spectrum of three star-forming clouds}, volume = {981}, year = {2025}, }
• (2025). Search for neutrino emission from hard X-ray AGN with IceCube. ApJ, 981(2), 131. (www)

  @article{ , abstract = {Active galactic nuclei (AGN) are promising candidate sources of high-energy astrophysical neutrinos, since they provide environments rich in matter and photon targets where cosmic-ray interactions may lead to the production of gamma rays and neutrinos. We searched for high-energy neutrino emission from AGN using the Swift-BAT Spectroscopic Survey catalog of hard X-ray sources and 12 yr of IceCube muon track data. First, upon performing a stacked search, no significant emission was found. Second, we searched for neutrinos from a list of 43 candidate sources and found an excess from the direction of two sources, the Seyfert galaxies NGC 1068 and NGC 4151. We observed NGC 1068 at flux {\phi }_{{\nu }_{\mu }+{\bar{\nu }}_{\mu }} = 4.0{2}_{-1.52}^{+1.58}\times 1{0}^{-11} TeV −1 cm −2 s −1 normalized at 1 TeV, with a power-law spectral index γ = 3.10 {}_{-0.22}^{+0.26} , consistent with previous IceCube results. The observation of a neutrino excess from the direction of NGC 4151 is at a posttrial significance of 2.9 σ . If interpreted as an astrophysical signal, the excess observed from NGC 4151 corresponds to a flux {\phi }_{{\nu }_{\mu }+{\bar{\nu }}_{\mu }} = 1.5{1}_{-0.81}^{+0.99}\times 1{0}^{-11} TeV −1 cm −2 s −1 normalized at 1 TeV and γ = 2.83 {}_{-0.28}^{+0.35} .}, archive = {J_ApJ}, author = {R. Abbasi and M. Ackermann and J. Adams and S. K. Agarwalla and J. A. Aguilar and M. Ahlers and J.M. Alameddine and N. M. Amin and K. Andeen and C. Argüelles and Y. Ashida and S. Athanasiadou and L. Ausborm and S. N. Axani and X. Bai and A. Balagopal V. and M. Baricevic and S. W. Barwick and S. Bash and V. Basu and R. Bay and J. J. Beatty and J. Becker Tjus and J. Beise and C. Bellenghi and C. Benning and S. BenZvi and D. Berley and E. Bernardini and D. Z. Besson and E. Blaufuss and L. Bloom and S. Blot and F. Bontempo and J. Y. Book Motzkin and C. Boscolo Meneguolo and S. Böser and O. Botner and J. Böttcher and J. Braun and B. Brinson and J. Brostean-Kaiser and L. Brusa and R. T. Burley and D. Butterfield and M. A. Campana and I. Caracas and K. Carloni and J. Carpio and S. Chattopadhyay and N. Chau and Z. Chen and D. Chirkin and S. Choi and B. A. Clark and A. Coleman and G. H. Collin and A. Connolly and J. M. Conrad and P. Coppin and R. Corley and P. Correa and D. F. Cowen and P. Dave and C. De Clercq and J. J. DeLaunay and D. Delgado and S. Deng and A. Desai and P. Desiati and K. D. de Vries and G. de Wasseige and T. DeYoung and A. Diaz and J. C. Díaz-Vélez and P. Dierichs and M. Dittmer and A. Domi and L. Draper and H. Dujmovic and K. Dutta and M. A. DuVernois and T. Ehrhardt and L. Eidenschink and A. Eimer and P. Eller and E. Ellinger and S. El Mentawi and D. Elsässer and R. Engel and H. Erpenbeck and J. Evans and P. A. Evenson and K. L. Fan and K. Fang and K. Farrag and A. R. Fazely and A. Fedynitch and N. Feigl and S. Fiedlschuster and C. Finley and L. Fischer and D. Fox and A. Franckowiak and S. Fukami and P. Fürst and J. Gallagher and E. Ganster and A. Garcia and M. Garcia and G. Garg and E. Genton and L. Gerhardt and A. Ghadimi and C. Girard-Carillo and C. Glaser and T. Glüsenkamp and J. G. Gonzalez and S. Goswami and A. Granados and D. Grant and S. J. Gray and O. Gries and S. Griffin and S. Griswold and K. M. Groth and C. Günther and P. Gutjahr and C. Ha and C. Haack and A. Hallgren and L. Halve and F. Halzen and H. Hamdaoui and M. Ha Minh and M. Handt and K. Hanson and J. Hardin and A. A. Harnisch and P. Hatch and A. Haungs and J. Häussler and K. Helbing and J. Hellrung and J. Hermannsgabner and L. Heuermann and N. Heyer and S. Hickford and A. Hidvegi and C. Hill and G. C. Hill and K. D. Hoffman and S. Hori and K. Hoshina and M. Hostert and W. Hou and T. Huber and K. Hultqvist and M. Hünnefeld and R. Hussain and K. Hymon and A. Ishihara and W. Iwakiri and M. Jacquart and O. Janik and M. Jansson and G. S. Japaridze and M. Jeong and M. Jin and B. J. P. Jones and N. Kamp and D. Kang and W. Kang and X. Kang and A. Kappes and D. Kappesser and L. Kardum and T. Karg and M. Karl and A. Karle and A. Katil and U. Katz and M. Kauer and J. L. Kelley and M. Khanal and A. Khatee Zathul and A. Kheirandish and J. Kiryluk and S. R. Klein and A. Kochocki and R. Koirala and H. Kolanoski and T. Kontrimas and L. Köpke and C. Kopper and D. J. Koskinen and P. Koundal and M. Kovacevich and M. Kowalski and T. Kozynets and J. Krishnamoorthi and K. Kruiswijk and E. Krupczak and A. Kumar and E. Kun and N. Kurahashi and N. Lad and C. Lagunas Gualda and M. Lamoureux and M. J. Larson and S. Latseva and F. Lauber and J. P. Lazar and J. W. Lee and K. Leonard DeHolton and A. Leszczyńska and J. Liao and M. Lincetto and Y. T. Liu and M. Liubarska and E. Lohfink and C. Love and C. J. Lozano Mariscal and L. Lu and F. Lucarelli and W. Luszczak and Y. Lyu and J. Madsen and E. Magnus and K. B. M. Mahn and Y. Makino and E. Manao and S. Mancina and W. Marie Sainte and I. C. Mariş and S. Marka and Z. Marka and M. Marsee and I. Martinez-Soler and R. Maruyama and F. Mayhew and F. McNally and J. V. Mead and K. Meagher and S. Mechbal and A. Medina and M. Meier and Y. Merckx and L. Merten and J. Micallef and J. Mitchell and T. Montaruli and R. W. Moore and Y. Morii and R. Morse and M. Moulai and T. Mukherjee and R. Naab and R. Nagai and M. Nakos and U. Naumann and J. Necker and A. Negi and L. Neste and M. Neumann and H. Niederhausen and M. U. Nisa and K. Noda and A. Noell and A. Novikov and A. Obertacke Pollmann and V. O’Dell and B. Oeyen and A. Olivas and R. Orsoe and J. Osborn and E. O’Sullivan and H. Pandya and N. Park and G. K. Parker and E. N. Paudel and L. Paul and C. Pérez de los Heros and T. Pernice and J. Peterson and S. Philippen and A. Pizzuto and M. Plum and A. Pontén and Y. Popovych and M. Prado Rodriguez and B. Pries and G. C. Privon and R. Procter-Murphy and G. T. Przybylski and C. Raab and J. Rack-Helleis and M. Ravn and K. Rawlins and Z. Rechav and A. Rehman and P. Reichherzer and E. Resconi and S. Reusch and W. Rhode and B. Riedel and A. Rifaie and E. J. Roberts and S. Robertson and S. Rodan and G. Roellinghoff and M. Rongen and A. Rosted and C. Rott and T. Ruhe and L. Ruohan and D. Ryckbosch and I. Safa and J. Saffer and D. Salazar-Gallegos and P. Sampathkumar and A. Sandrock and M. Santander and S. Sarkar and J. Savelberg and P. Savina and P. Schaile and M. Schaufel and H. Schieler and S. Schindler and B. Schlüter and F. Schlüter and N. Schmeisser and T. Schmidt and J. Schneider and F. G. Schröder and L. Schumacher and S. Sclafani and D. Seckel and M. Seikh and M. Seo and S. Seunarine and P. Sevle Myhr and R. Shah and S. Shefali and N. Shimizu and M. Silva and B. Skrzypek and B. Smithers and R. Snihur and J. Soedingrekso and A. Sègaard and D. Soldin and P. Soldin and G. Sommani and C. Spannfellner and G. M. Spiczak and C. Spiering and M. Stamatikos and T. Stanev and T. Stezelberger and T. Stürwald and T. Stuttard and G. W. Sullivan and I. Taboada and S. Ter-Antonyan and A. Terliuk and M. Thiesmeyer and W. G. Thompson and J. Thwaites and S. Tilav and K. Tollefson and C. Tönnis and S. Toscano and D. Tosi and A. Trettin and R. Turcotte and J. P. Twagirayezu and M. A. Unland Elorrieta and A. K. Upadhyay and K. Upshaw and A. Vaidyanathan and N. Valtonen-Mattila and J. Vandenbroucke and N. van Eijndhoven and D. Vannerom and J. van Santen and J. Vara and F. Varsi and J. Veitch-Michaelis and M. Venugopal and M. Vereecken and S. Verpoest and D. Veske and A. Vijai and C. Walck and A. Wang and C. Weaver and P. Weigel and A. Weindl and J. Weldert and A. Y. Wen and C. Wendt and J. Werthebach and M. Weyrauch and N. Whitehorn and C. H. Wiebusch and D. R. Williams and L. Witthaus and A. Wolf and M. Wolf and G. Wrede and X. W. Xu and J. P. Yanez and E. Yildizci and S. Yoshida and R. Young and S. Yu and T. Yuan and Z. Zhang and P. Zhelnin and P. Zilberman and M. Zimmerman and IceCube Collaboration}, doi = {10.3847/1538-4357/ada94b}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {131}, shortjournal = {The Astrophys. J.}, title = {Search for neutrino emission from hard X-ray AGN with IceCube}, volume = {981}, year = {2025}, }
• (2025). A new spectral library for modeling the surfaces of hot, rocky exoplanets. ApJ, 981(2), 130. (www)

  @article{ , abstract = {JWST's MIRI LRS provides the first opportunity to spectroscopically characterize the surface compositions of close-in terrestrial exoplanets. Models for the bare-rock spectra of these planets often utilize a spectral library from R. Hu et al., which is based on room-temperature reflectance measurements of materials that represent archetypes of rocky planet surfaces. Here we present an expanded library that includes hemispherical reflectance measurements for a greater variety of compositions, varying textures (solid slab, coarsely crushed, and fine powder), as well as high-temperature (500–800 K) emissivity measurements for select samples. We incorporate this new library into version 6.3 of the open-source retrieval package PLATON and use it to show that planetary surfaces with similar compositions can have widely varying albedos and surface temperatures. We additionally demonstrate that changing the texture of a material can significantly alter its albedo, making albedo a poor proxy for surface composition. We identify key spectral features—the 5.6 μ m olivine feature, the transparency feature, the Si-O stretching feature, and the Christiansen feature—that indicate silicate abundance and surface texture. We quantify the number of JWST observations needed to detect these features in the spectrum of the most favorable super-Earth target, LHS 3844 b, and revisit the interpretation of its Spitzer photometry. Lastly, we show that temperature-dependent changes in spectral features are likely undetectable at the precision of current exoplanet observations. Our results illustrate the importance of spectroscopically resolved thermal emission measurements, as distinct from surface albedo constraints, for characterizing the surface compositions of hot, rocky exoplanets.}, archive = {J_ApJ}, author = {Kimberly Paragas and Heather A. Knutson and Renyu Hu and Bethany L. Ehlmann and Giulia Alemanno and Jörn Helbert and Alessandro Maturilli and Michael Zhang and Aishwarya Iyer and George Rossman}, doi = {10.3847/1538-4357/ada9eb}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {130}, shortjournal = {The Astrophys. J.}, title = {A new spectral library for modeling the surfaces of hot, rocky exoplanets}, volume = {981}, year = {2025}, }
• (2025). Dormancy and reawakening over years: Eight new recurrent changing-look AGNs. ApJ, 981(2), 129. (www)

  @article{ , abstract = {We report the discovery of eight new recurrent changing-look (CL) active galactic nuclei (AGNs), consisting of seven rebrightening turn-off AGNs and one fading turn-on AGN. These systems are valuable for placing constraints on the duration of dim and bright states, which may be linked to the AGN duty cycle or disk instability. Long-term analysis of optical light curves reveals that many objects in our sample exhibit a prolonged plateau during the dim states lasting 5–7 yr, with a gradual turn-on/off process. We observe no significant difference between the turn-on and turn-off timescales, and this timescale is broadly consistent with the propagation timescale for the heating/cooling front. Comparison between the optical and infrared variations supports the idea that these transitions are driven by changes in accretion disk emission rather than dust obscuration. Our discovery significantly increases the previously identified recurrent CL AGN sample, demonstrating that some AGNs can enter dormancy and reawaken on timescales of a few years, which provides useful information for understanding episodic AGN accretion.}, archive = {J_ApJ}, author = {Shu Wang and Jong-Hak Woo and Elena Gallo and Donghoon Son and Qian Yang and Junjie Jin and Hengxiao Guo and Minzhi Kong}, doi = {10.3847/1538-4357/adadf3}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {129}, shortjournal = {The Astrophys. J.}, title = {Dormancy and reawakening over years: Eight new recurrent changing-look AGNs}, volume = {981}, year = {2025}, }
• (2025). B-fields and dust in interstellar filaments using dust polarization (BALLAD-POL). III. grain alignment and disruption mechanisms in g34.43+0.24 using polarization observations from JCMT/POL-2. ApJ, 981(2), 128. (www)

  @article{ , abstract = {Polarization of starlight and thermal dust emission due to aligned non-spherical grains helps us to trace magnetic field ( B -field) morphology in molecular clouds and to study grain alignment mechanisms. In this work, we study grain alignment and disruption mechanisms in a filamentary infrared dark cloud G34.43+0.24 using thermal dust polarization observations from JCMT/POL-2 at 850 μ m. We study three regions: the North harboring the MM3 core, the Center harboring the MM1 and MM2 cores, and the South harboring no core. We find the decrease in polarization fraction P with increasing total intensity and gas column density, known as polarization hole. To disentangle the effect of magnetic field tangling on the polarization hole, we estimate the polarization angle dispersion function. We find depolarizations in the North and Center regions are due to a decrease in the net alignment efficiency of grains, but in the South region, the effect of magnetic field tangling is significant to cause depolarization. To test whether the radiative torque (RAT) mechanism can reproduce the observational data, we calculate minimum alignment and disruption sizes of grains using RAT theory, and our study finds that the RAT alignment (RAT-A) mechanism can explain the depolarizations in the North and Center regions where the B -field tangling effect is less important, except for core regions. We find hints of RAT disruption (RAT-D) in the core regions of MM3 in the North, and MM1 and MM2 in the Center. We also find that the high P value of around 8%–20% in the outer regions of the filament can potentially be explained by the magnetically enhanced RAT alignment mechanism.}, archive = {J_ApJ}, author = {Saikhom Pravash and Archana Soam and Pham Ngoc Diep and Thiem Hoang and Nguyen Bich Ngoc and Le Ngoc Tram}, doi = {10.3847/1538-4357/adae06}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {128}, shortjournal = {The Astrophys. J.}, title = {B-fields and dust in interstellar filaments using dust polarization (BALLAD-POL). III. grain alignment and disruption mechanisms in g34.43+0.24 using polarization observations from JCMT/POL-2}, volume = {981}, year = {2025}, }
• (2025). A detailed look at a trio of changing-look quasars: Spectral energy distributions and the dust extinction test*†. ApJ, 981(2), 127. (www)

  @article{ , abstract = {Changing-look quasars (CLQs) exhibit dramatic variability in broad emission-line fluxes on short timescales. This behavior is challenging to many models of the quasar broad-line region, due in large part to the short transition times between high and low states. In order to constrain the cause of the dramatic variability, we obtained contemporaneous Hubble Space Telescope ultraviolet and Hobby Eberly Telescope optical spectra of three CLQs caught in their low state. We use these spectra, along with archival spectra taken during both the high and low states, to investigate potential scenarios for the change in state. Our data strongly disfavor a variable dust obscuration scenario for these three CLQs, and instead suggest that the observed transformation reflects a change in the intrinsic luminosity of the central engine. We also find that the low-state spectral energy distributions of all three quasars are reminiscent of those of low-luminosity active galactic nuclei, which suggests that the transition may result from a change in accretion flow structure caused by a reduced Eddington ratio.}, archive = {J_ApJ}, author = {Laura Duffy and Michael Eracleous and Jessie C. Runnoe and John J. Ruan and Scott F. Anderson and Sabrina Dimassimo and Paul Green and Stephanie LaMassa}, doi = {10.3847/1538-4357/adae0b}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {127}, shortjournal = {The Astrophys. J.}, title = {A detailed look at a trio of changing-look quasars: Spectral energy distributions and the dust extinction test*†}, volume = {981}, year = {2025}, }
• (2025). Tracking X-ray variability in next-generation EHT low-luminosity active galactic nucleus targets. ApJ, 981(2), 126. (www)

  @article{ , abstract = {We present a 5 month NICER X-ray monitoring campaign for two low-luminosity active galactic nuclei (LLAGNs)—NGC 4594 and IC 1459—with complementary Swift and NuSTAR observations. Utilizing an absorbed power-law and thermal source model combined with NICER's SCORPEON background model, we demonstrate the effectiveness of joint source–background modeling for constraining emission from faint, background-dominated targets. Both sources are dominated by nuclear power-law emission with photon indices Γ ∼ 1.5–2, with NGC 4594 being slightly harder than IC 1459. The thermal contribution in both sources is fainter, but constant, with kT ∼ 0.5 keV (∼5 × 10 6 K). The power-law flux and Γ are strongly anticorrelated in both sources, as has been seen for other LLAGNs with radiatively inefficient accretion flows. NGC 4594 is the brighter source and exhibits significant aperiodic variability. Its variability timescale with an upper limit of 5–7 days indicates emission originating from ≲100 r g , at the scale of the inner accretion flow. A spectral break found at ∼6 keV, while tentative, could arise from synchrotron/inverse Compton emission. This high-cadence LLAGN X-ray monitoring campaign underlines the importance of multiwavelength variability studies for a sample of LLAGNs to truly understand their accretion and outflow physics.}, archive = {J_ApJ}, author = {Nicole M. Ford and Michael Nowak and Venkatessh Ramakrishnan and Daryl Haggard and Kristen Dage and Dhanya G. Nair and Chi-kwan Chan}, doi = {10.3847/1538-4357/adae0f}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {126}, shortjournal = {The Astrophys. J.}, title = {Tracking X-ray variability in next-generation EHT low-luminosity active galactic nucleus targets}, volume = {981}, year = {2025}, }
• (2025). Multiwavelength observations of a jet launch in real time from the post-changing-look active galaxy 1ES 1927+654. ApJ, 981(2), 125. (www)

  @article{ , abstract = {We present results from a high-cadence multiwavelength observational campaign of the enigmatic changing-look active galactic nucleus 1ES 1927+654 from 2022 May to 2024 April, coincident with an unprecedented radio flare (an increase in flux by a factor of ∼60 over a few months) and the emergence of a spatially resolved jet at 0.1–0.3 pc scales. Companion work has also detected a recurrent quasi-periodic oscillation (QPO) in the 2–10 keV band with an increasing frequency (1–2 mHz) over the same period. During this time, the soft X-rays (0.3–2 keV) monotonically increased by a factor of ∼8, while the UV emission remained nearly steady with <30% variation and the 2–10 keV flux showed variation by a factor ≲2. The weak variation of the 2–10 keV X-ray emission and the stability of the UV emission suggest that the magnetic energy density and accretion rate are relatively unchanged and that the jet could be launched owing to a reconfiguration of the magnetic field (toroidal to poloidal) close to the black hole. Advecting poloidal flux onto the event horizon would trigger the Blandford–Znajek mechanism, leading to the onset of the jet. The concurrent softening of the coronal slope (from Γ = 2.70 ± 0.04 to Γ = 3.27 ± 0.04), the appearance of a QPO, and the low coronal temperature ( k{T}_{e}={8}_{-3}^{+8}\,\,{\rm{keV}} ) during the radio outburst suggest that the poloidal field reconfiguration can significantly impact coronal properties and thus influence jet dynamics. These extraordinary findings in real time are crucial for coronal and jet plasma studies, particularly as our results are independent of coronal geometry.}, archive = {J_ApJ}, author = {Sibasish Laha and Eileen T. Meyer and Dev R. Sadaula and Ritesh Ghosh and Dhrubojyoti Sengupta and Megan Masterson and Onic I. Shuvo and Matteo Guainazzi and Claudio Ricci and Mitchell C. Begelman and Alexander Philippov and Rostom Mbarek and Amelia M. Hankla and Erin Kara and Francesca Panessa and Ehud Behar and Haocheng Zhang and Fabio Pacucci and Main Pal and Federica Ricci and Ilaria Villani and Susanna Bisogni and Fabio La Franca and Stefano Bianchi and Gabriele Bruni and Samantha Oates and Cameron Hahn and Matt Nicholl and S. Bradley Cenko and Sabyasachi Chattopadhyay and Josefa Becerra González and J. A. Acosta–Pulido and Suvendu Rakshit and Jiří Svoboda and Luigi Gallo and Adam Ingram and Darshan Kakkad}, doi = {10.3847/1538-4357/adaea0}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {125}, shortjournal = {The Astrophys. J.}, title = {Multiwavelength observations of a jet launch in real time from the post-changing-look active galaxy 1ES 1927+654}, volume = {981}, year = {2025}, }
• (2025). Disrupted wide binaries as dynamical probes of galactic structure. ApJ, 981(2), 124. (www)

  @article{ , abstract = {Many of the stars in the Galaxy are members of binary systems, the widest of which can eventually become disrupted due to a combination of kicks from passing objects and the Galactic tidal field. If the Galactic disk were purely axisymmetric, the stars from a disrupted binary system would slowly drift apart on nearly identical orbits. We study how the existence of nonaxisymmetric structures, such as a rigidly rotating bar, can greatly alter this picture. In particular, we show how the orbital dynamics near the resonances sourced by these nonaxisymmetric perturbations create local fluctuations in the distribution of disrupted binary separations. We simulate the evolution of wide binary systems embedded in a gravitational potential with a rotating galactic bar, and show how features and fluctuations in the distribution of disrupted binaries can be used to locate bar resonances and constrain the bar's pattern speed and amplitude.}, archive = {J_ApJ}, author = {Tomer D. Yavetz}, doi = {10.3847/1538-4357/adaeac}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {124}, shortjournal = {The Astrophys. J.}, title = {Disrupted wide binaries as dynamical probes of galactic structure}, volume = {981}, year = {2025}, }
• (2025). On gamma rays as predictors of ultra-high-energy cosmic-ray flux in active galactic nuclei. ApJ, 981(2), 123. (www)

  @article{ , abstract = {Active galactic nuclei (AGN) are among the main candidates for ultra-high-energy cosmic-ray (UHECR) sources. However, while some theoretical and phenomenological works favor AGNs as the main sources, recent works have shown that using the very-high-energy γ -ray flux as a proxy for the UHECR flux leads to a bad agreement with data. In this context, the energy spectrum and composition data are hardly fitted. At the same time, the arrival directions map is badly described and a spurious dipole direction is produced. In this work, we propose a possible solution to these contradictions. Using the observed γ -ray flux as a proxy may carry the implicit assumption of beamed UHECR emission and, consequently, its beam will remain collimated up to its detection on Earth. We show that assuming an isotropic UHECR emission and correcting the γ -ray emission proxy by Doppler boosting can overcome the problem. The combined fit of the spectrum and composition is improved, with a change of reduced χ 2 from 4.6 to 3.1. In particular, the tension between the observed and modeled dipole directions can be reduced from 5.9 (2.1) σ away from the data to 3.5 (1.1) σ for E > 8 EeV ( E > 32 EeV). We also show that this effect is particularly important when including AGNs of different classes in the same analysis, such as radio galaxies and blazars.}, archive = {J_ApJ}, author = {Cainã de Oliveira and Rodrigo Guedes Lang and Pedro Batista}, doi = {10.3847/1538-4357/adafa2}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {123}, shortjournal = {The Astrophys. J.}, title = {On gamma rays as predictors of ultra-high-energy cosmic-ray flux in active galactic nuclei}, volume = {981}, year = {2025}, }
• (2025). A second radio flare from the tidal disruption event AT2020vwl: A delayed outflow ejection?. ApJ, 981(2), 122. (www)

  @article{ , abstract = {We present the discovery of a second radio flare from the tidal disruption event (TDE) AT2020vwl via long-term monitoring radio observations. Late-time radio flares from TDEs are being discovered more commonly, with many TDEs showing radio emission thousands of days after the stellar disruption, but the mechanism that powers these late-time flares is uncertain. Here, we present radio spectral observations of the first and second radio flares observed from the TDE AT2020vwl. Through detailed radio spectral monitoring, we find evidence for two distinct outflow ejection episodes or a period of renewed energy injection into the preexisting outflow. We deduce that the second radio flare is powered by an outflow that is initially slower than the first flare but carries more energy and shows tentative indication of accelerating over time. Through modelling the long-term optical and UV emission from the TDE as arising from an accretion disk, we infer that the second radio outflow launch or energy injection episode occurred approximately at the time of the peak accretion rate. The fast decay of the second flare precludes environmental changes as an explanation, while the velocity of the outflow is at all times too low to be explained by an off-axis relativistic jet. Future observations that search for any link between the accretion disk properties and late-time radio flares from TDEs will aid understanding of what powers the radio outflows in TDEs and confirm if multiple outflow ejections or energy injection episodes are common.}, archive = {J_ApJ}, author = {A. J. Goodwin and A. Mummery and T. Laskar and K. D. Alexander and G. E. Anderson and M. Bietenholz and C. Bonnerot and C. T. Christy and W. Golay and W. Lu and R. Margutti and J. C. A. Miller-Jones and E. Ramirez-Ruiz and R. Saxton and S. van Velzen}, doi = {10.3847/1538-4357/adb0b1}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {122}, shortjournal = {The Astrophys. J.}, title = {A second radio flare from the tidal disruption event AT2020vwl: A delayed outflow ejection?}, volume = {981}, year = {2025}, }
• (2025). On the magnetic and thermodynamic properties of dark fibrils in the chromosphere. ApJ, 981(2), 121. (www)

  @article{ , abstract = {Fibrillar structures are ubiquitous in the solar chromosphere. An accurate determination of their properties requires the use of advanced high-resolution observations, which are now becoming broadly available from different observatories. We exploit the capabilities of multi-atom, multiline spectropolarimetric inversions using the Stockholm Inversion Code. Non–local thermodynamic equilibrium inversions of a fibril-rich area are performed using spectropolarimetric observations on the Ca ii 854.2 nm line obtained with the CRISP imaging spectropolarimeter and spectroscopic observations on the Ca ii H line obtained with the CHROMospheric Imaging Spectrometer at the Swedish 1 m Solar Telescope. Additionally, co-observations on the Mg ii h and k lines obtained with the Interface Region Imaging Spectrograph are used in the inversions to better constrain the thermodynamic properties of the fibrils. The incorporation of multiple atomic species and spectral lines proves to better constrain the properties of the plasma constituting the fibrils. In particular, the tracing of a large number of fibrils allowed for the study of the variation of the temperature and magnetic field along their projected length over the field of view. The results provide a view of fibrils possessing hot footpoints of about 5900 K. The temperature drop away from the footpoints is on average 250 K, with a larger drop of around 500 K for the longer fibrils. The magnetic field is also reported to be larger at the footpoints, being almost twice as large as the minimum value reported at the middle point of the fibrils.}, archive = {J_ApJ}, author = {Matheus Kriginsky and Ramon Oliver}, doi = {10.3847/1538-4357/adb0b4}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {121}, shortjournal = {The Astrophys. J.}, title = {On the magnetic and thermodynamic properties of dark fibrils in the chromosphere}, volume = {981}, year = {2025}, }
• (2025). Unusual X-ray oxygen line ratios of SN 1987A arising from the absorption of galactic hot interstellar medium. ApJ, 981(2), 120. (www)

  @article{ , abstract = {Recent high-resolution X-ray spectroscopic studies have revealed unusual oxygen line ratios, such as the high O vii forbidden-to-resonance ratio, in several supernova remnants. While the physical origin is still under debate, for most of them it has been suggested that this phenomenon arises from either charge exchange (CX) or resonant scattering (RS). In this work, we report the high O vii G-ratio (≳1) and high O viii Ly β /Ly α ratio (≳0.2) found in multiepoch XMM-Newton Reflection Grating Spectrometer observations of SN 1987A. The line ratios cannot be fully explained by nonequilibrium ionization effects, CX, or RS. We suggest the absorption of foreground hot gas as the most likely origin, which plays the major role in modifying line fluxes and line ratios. Based on this scenario, we introduced two Gaussian absorption components at the O vii resonance line and the O viii Ly α line and constrained the optical depth of the two lines as τ O VII ∼ 0.6 and τ O VIII ∼ 0.2. We estimated the temperature as kT e ∼ 0.15 keV and the oxygen column density as N O ∼0.5 × 10 16 cm −2 for the absorbing gas, which is consistent with the hot interstellar medium in the Galactic halo. Neglecting this absorption component may lead to an underestimation of the O abundance. We revised the O abundance of SN 1987A, which is increased by ∼20% compared with previous results. The N/O ratio by number of atoms is revised to be ∼1.2.}, archive = {J_ApJ}, author = {Lei Sun and Salvatore Orlando and Emanuele Greco and Marco Miceli and Yiping Li and Yang Chen and Jacco Vink and Ping Zhou}, doi = {10.3847/1538-4357/adb0b5}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {120}, shortjournal = {The Astrophys. J.}, title = {Unusual X-ray oxygen line ratios of SN 1987A arising from the absorption of galactic hot interstellar medium}, volume = {981}, year = {2025}, }
• (2025). Powerful explosions from the collapse of rotating supermassive stars. ApJ, 981(2), 119. (www)

  @article{ , abstract = {We perform new general relativistic hydrodynamics simulations for collapses of rotating supermassive star cores with an approximate nuclear burning up to carbon and a detailed equation of state. For all the models we investigate, the energy generation by nuclear burning plays only a minor role, leading to the formation of a black hole without a nuclear-powered explosion. For rotating models, however, the stellar explosion associated with shock heating is driven from a torus, which forms after the black hole formation. The explosion energy is up to 10 −4 of the mass energy of the supermassive star cores (∼10 55 –10 56 erg). We find that, even if we increase the rotational angular momentum of the progenitor, the ejecta mass saturates at ∼1% of the total mass of the initial stellar core. The average ejecta velocity also saturates at ≈20% of the speed of light. As a result, the ejecta kinetic energy is approximately proportional to the initial mass of the supermassive star core for the rapidly rotating case. We also perform viscous hydrodynamics simulations to explore the evolution of the remnant torus. Although the viscous heating drives an outflow from the torus, we find that its effect is subdominant in terms of the kinetic energy because of the small velocity (≈0.07 c ) of the ejecta component.}, archive = {J_ApJ}, author = {Sho Fujibayashi and Cédric Jockel and Kyohei Kawaguchi and Yuichiro Sekiguchi and Masaru Shibata}, doi = {10.3847/1538-4357/adb0b8}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {119}, shortjournal = {The Astrophys. J.}, title = {Powerful explosions from the collapse of rotating supermassive stars}, volume = {981}, year = {2025}, }
• (2025). Probing X-ray timing and spectral variability in the blazar PKS 2155–304 over a decade of XMM-newton observations. ApJ, 981(2), 118. (www)

  @article{ , abstract = {Blazars, a class of active galactic nuclei (AGN) powered by supermassive black holes, are known for their remarkable variability across multiple timescales and wavelengths. Despite significant advancements in our understanding of AGN central engines, thanks to both ground- and space-based telescopes, the details of the mechanisms driving this variability remain elusive. The primary objective of this study is to constrain the X-ray variability properties of the TeV blazar PKS 2155–304. We conducted a comprehensive X-ray spectral and timing analysis, focusing on both long-term and intraday variability (IDV), using data from 22 epochs of XMM-Newton observations collected over 15 yr (2000–2014). For the timing analysis, we estimated the fractional variability, variability amplitude, minimum variability timescales, flux distribution, and power spectral density. In the spectral analysis, we fitted the X-ray spectra using power-law, log-parabola, and broken power-law models to determine the best-fitting parameters. We observed moderate IDV in the majority of the light curves (LCs). Seven out of the 22 observations showed a clear bimodal flux distribution, indicating the presence of two distinct flux states. Our analysis revealed a variable power spectral slope. Most hardness ratio plots did not show significant variation with flux, except for two observations, where the hardness ratio changed considerably with flux. The fitted X-ray spectra favored the broken power-law model for the majority of observations, indicating a break in the spectral profiles. The findings of this work shed light on the IDV of blazars, providing insights into the nonthermal jet processes that drive the observed flux variations.}, archive = {J_ApJ}, author = {Gopal Bhatta and Suvas Chandra Chaudhary and Niraj Dhital and Tek P. Adhikari and Maksym Mohorian and Adithiya Dinesh and Radim Pánis and Raghav Neupane and Yogesh Singh Maharjan}, doi = {10.3847/1538-4357/adb0c9}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {118}, shortjournal = {The Astrophys. J.}, title = {Probing X-ray timing and spectral variability in the blazar PKS 2155–304 over a decade of XMM-newton observations}, volume = {981}, year = {2025}, }
• (2025). Using neural networks to automate the identification of brightest cluster galaxies in large surveys. ApJ, 981(2), 117. (www)

  @article{ , abstract = {Brightest cluster galaxies (BCGs) lie deep within the largest gravitationally bound structures in existence. Though some cluster finding techniques identify the position of the BCG and use it as the cluster center, other techniques may not automatically include these coordinates. This can make studying BCGs in such surveys difficult, forcing researchers to either adopt oversimplified algorithms or perform cumbersome visual identification. For large surveys, there is a need for a fast and reliable way of obtaining BCG coordinates. We propose machine learning to accomplish this task and train a neural network to identify positions of candidate BCGs given no more information than multiband photometric images. We use both mock observations from The Three Hundred project and real ones from the Sloan Digital Sky Survey, and we quantify the performance. Training on simulations yields a squared correlation coefficient, R 2 , between predictions and ground truth of R 2 ≈ 0.94 when testing on simulations, which decreases to R 2 ≈ 0.60 when testing on real data owing to discrepancies between data sets. Limiting the application of this method to real clusters more representative of the training data, such as those with a BCG r -band magnitude r BCG ≤ 16.5, yields R 2 ≈ 0.99. The method performs well up to a redshift of at least z ≈ 0.6. We find this technique to be a promising method to automate and accelerate the identification of BCGs in large data sets.}, archive = {J_ApJ}, author = {Patrick Janulewicz and Tracy M. A. Webb and Laurence Perreault-Levasseur}, doi = {10.3847/1538-4357/adb1ad}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {117}, shortjournal = {The Astrophys. J.}, title = {Using neural networks to automate the identification of brightest cluster galaxies in large surveys}, volume = {981}, year = {2025}, }
• (2025). Using polar faculae to determine the sun’s high-latitude rotation rate. II. simulations and new measurements. ApJ, 981(2), 116. (www)

  @article{ , abstract = {In a previous paper, I described a new way of determining the high-latitude solar rotation rate statistically from spacetime maps of polar faculae observed in the 6767 Å continuum by the Michelson Doppler Interferometer on the Solar and Heliospheric Observatory. Now, I have tested the technique by applying it to simulated images whose faculae have known speeds, and I have been able to recover those speeds with an accuracy better than 0.01 km s −1 . Repeated measurements of the Sun's polar faculae gave the same high-latitude profile as before, but with a slightly faster synodic rotation rate of 9.10^\circ \,{\mathrm{day}}^{-1} and a rotation period of 39.6 days. Applying this spacetime tracking procedure to magnetic flux elements observed with the Helioseismic Magnetic Imager on the Solar Dynamics Observatory, I obtained a similar rotation profile with a speed of 9.55° day −1 and a synodic rotation period of 37.7 days. These rates are comparable to polar rotation rates, obtained by other techniques, but the new latitude profiles are noticeably flatter than the quartic fits to those prior measurements.}, archive = {J_ApJ}, author = {Neil R. Sheeley}, doi = {10.3847/1538-4357/adb1af}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {116}, shortjournal = {The Astrophys. J.}, title = {Using polar faculae to determine the sun’s high-latitude rotation rate. II. simulations and new measurements}, volume = {981}, year = {2025}, }
• (2025). Spiral density waves in the multiple-armed galaxy NGC 628. ApJ, 981(2), 115. (www)

  @article{ , abstract = {Radial profiles of pattern speeds are measured at subkiloparsec resolution for NGC 628. The radial profiles are directly measured using a general form of the Tremaine–Weinberg method that allows for the pattern speed to vary with radius. The method is applied to both stars and CO, H i , and H α spectral lines. The trends in the results are consistent for all of the data, showing that sources and sinks in the interstellar medium have a negligible effect when applying the integrated continuity equation. The spiral pattern rotates at a greater angular frequency in the inner region of the disks than in their outer region. Most of the measured values of the pattern speed are less than the material speed. The results for the inner disk show an approximately constant trend, consistent with rigidly rotating density waves. The offsets in stellar photometric and spectral line intensity data corroborate this result. There are radially decreasing trends in the results for the outer region of the disks that are similar to the material speed, consistent with shearing patterns or what is expected for overlapping wave modes of decreasing pattern speed. There is no single theory for the origin of the spiral patterns that can explain all of the results, but the results fail to provide evidence for a single global wave mode.}, archive = {J_ApJ}, author = {Jason C. Speights and Virginia Aust and Qinyan Lu}, doi = {10.3847/1538-4357/adb1b3}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {115}, shortjournal = {The Astrophys. J.}, title = {Spiral density waves in the multiple-armed galaxy NGC 628}, volume = {981}, year = {2025}, }
• (2025). A quasar-anchored protocluster at z = 6.6 in the ASPIRE survey. II. an environmental analysis of galaxy properties in an overdense structure. ApJ, 981(2), 114. (www)

  @article{ , abstract = {We present in this paper (Paper II of the series) a 35 arcmin 2 JWST/NIRCam imaging and wide-field slitless spectroscopy mosaic centered on J0305–3150, a luminous quasar at z = 6.61. The F356W grism data reveal 124 [O iii ]+H β emitters at 5.3 < z < 7, 53 of which constitute a protocluster spanning (10 cMpc) 2 across 6.5 < z < 6.8. We find no evidence of any broad-line active galactic nucleus (AGN) in individual galaxies or stacking, reporting a median H β FWHM of 585 ± 152 km s −1 ; however, the mass–excitation diagram and "little red dot" color and compactness criteria suggest that there are a few AGN candidates on the outskirts of the protocluster. We fit the spectral energy distributions (SEDs) of the [O iii ] emitters with Prospector and Bagpipes and find that none of the SED-derived properties (stellar mass, age, or star formation rate) correlate with proximity to the quasar. While there is no correlation between galaxy age and local galaxy density, we find modest correlations of local galaxy density with increasing stellar mass, decreasing 10–100 Myr star formation rate ratios, and decreasing nebular line equivalent widths. We further find that the protocluster galaxies are consistent with being more massive, being older, and hosting higher star formation rates than the field sample at the 3 σ level, distributed in a filamentary structure that supports inside-out formation of the protocluster. There is modest evidence that galaxy evolution proceeds differently as a function of the density of local environment within protoclusters during the epoch of reionization, and the central quasar has little effect on the galaxy properties of the surrounding structure.}, archive = {J_ApJ}, author = {Jaclyn B. Champagne and Feige Wang and Jinyi Yang and Xiaohui Fan and Joseph F. Hennawi and Fengwu Sun and Eduardo Bañados and Sarah E. I. Bosman and Tiago Costa and Melanie Habouzit and Xiangyu Jin and Hyunsung D. Jun and Mingyu Li and Weizhe Liu and Federica Loiacono and Alessandro Lupi and Chiara Mazzucchelli and Maria Pudoka and Sofía Rojas-Ruiz and Wei Leong Tee and Maxime Trebitsch and Haowen Zhang and Ming-Yang Zhuang and Siwei Zou}, doi = {10.3847/1538-4357/adb1bc}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {114}, shortjournal = {The Astrophys. J.}, title = {A quasar-anchored protocluster at z = 6.6 in the ASPIRE survey. II. an environmental analysis of galaxy properties in an overdense structure}, volume = {981}, year = {2025}, }
• (2025). A quasar-anchored protocluster at z = 6.6 in the ASPIRE survey. i. properties of [O iii] emitters in a 10 mpc overdensity structure. ApJ, 981(2), 113. (www)

  @article{ , abstract = {A SPectroscopic survey of bIased halos in the Reionization Era is a quasar legacy survey primarily using JWST to target a sample of 25 z > 6 quasars with NIRCam slitless spectroscopy and imaging. The first study in this series found evidence of a strong overdensity of galaxies around J0305−3150, a luminous quasar at z = 6.61, within a single NIRCam pointing obtained in JWST Cycle 1. Here we present the first results of a JWST Cycle 2 mosaic that covers 35 arcmin 2 with NIRCam imaging/wide-field slitless spectroscopy of the same field to investigate the spatial extent of the putative protocluster. The F356W grism data target [O iii ]+H β at 5.3 < z < 7 and reveal a population of 124 line emitters down to a flux limit of 1.2 × 10 −18 erg s −1 cm −2 . Fifty-three of these galaxies lie at 6.5 < z < 6.8 spanning 10 cMpc on the sky, corresponding to an overdensity within a 2500 cMpc 3 volume of 12.5 ± 2.6, anchored by the quasar. Comparing to the [O iii ] luminosity function from the Emission line galaxies and Intergalactic Gas in the Epoch of Reionization project, we find a dearth of faint [O iii ] emitters at log( L /erg s −1 ) < 42.3, which we suggest is consistent with either bursty star formation causing galaxies to scatter around the grism detection limit or modest suppression from quasar feedback. While we find a strong filamentary overdensity of [O iii ] emitters consistent with a protocluster, we suggest that we could be insensitive to a population of older, more massive Lyman break galaxies with weak nebular emission on scales >​​​​​​10 cMpc.}, archive = {J_ApJ}, author = {Jaclyn B. Champagne and Feige Wang and Haowen Zhang and Jinyi Yang and Xiaohui Fan and Joseph F. Hennawi and Fengwu Sun and Eduardo Bañados and Sarah E. I. Bosman and Tiago Costa and Anna-Christina Eilers and Ryan Endsley and Xiangyu Jin and Hyunsung D. Jun and Mingyu Li and Xiaojing Lin and Weizhe Liu and Federica Loiacono and Alessandro Lupi and Chiara Mazzucchelli and Maria Pudoka and Klaudia Protušovà and Sofía Rojas-Ruiz and Wei Leong Tee and Maxime Trebitsch and Bram P. Venemans and Ming-Yang Zhuang and Siwei Zou}, doi = {10.3847/1538-4357/adb1bd}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {113}, shortjournal = {The Astrophys. J.}, title = {A quasar-anchored protocluster at z = 6.6 in the ASPIRE survey. i. properties of [O iii] emitters in a 10 mpc overdensity structure}, volume = {981}, year = {2025}, }
• (2025). Unimolecular chemical kinetics in the interstellar environment: Competition of infrared radiation and collision activation mechanisms. ApJ, 981(2), 112. (www)

  @article{ , abstract = {Unimolecular gas phase chemical reactions could be activated by both infrared (IR) radiation and intermolecular collision in the interstellar environment. Understanding the interplay and competition between the radiation and collision activation mechanisms is crucial for assessing accurate reaction rate constants with an appropriate model. In this work, guided by an extended version of the Lindemann theory, we show that the relative importance of the two mechanisms can be measured by a dimensionless number PR that is the ratio of the collision frequency to the radiation absorption rate of the molecule. The reaction kinetics is dominated by collision activation or radiation activation depending on whether PR is larger or smaller than a reference value PR *, which is determined to be PR * ≈ 10 based on magnitudes of molecular properties, and is verified by detailed calculations of a number of typical interstellar unimolecular reactions. The determination of the PR number requires only information on the environment and molecular properties rather than detailed simulations of chemical reactions; thus, the PR number can serve as an indicator for a priori evaluations before detailed calculations. This method of evaluating the relative importance of the two mechanisms is checked against master equation calculations of two interstellar reactions, the dissociation reaction of silicic acid around an asymptotic giant branch star and the methyl radical association in Titan's atmosphere, and the validity is verified. The method can be used in the future to help determine the appropriate and effective modeling approach for chemical reactions in astrophysical environments.}, archive = {J_ApJ}, author = {Xiaorui Zhao and Rui Ming Zhang and Xuefei Xu and Haitao Xu}, doi = {10.3847/1538-4357/adb1df}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {112}, shortjournal = {The Astrophys. J.}, title = {Unimolecular chemical kinetics in the interstellar environment: Competition of infrared radiation and collision activation mechanisms}, volume = {981}, year = {2025}, }
• (2025). X-ray emission properties of a compact symmetric object sample. ApJ, 981(2), 111. (www)

  @article{ , abstract = {We present a comprehensive analysis of the X-ray observations obtained from XMM-Newton and Chandra for a sample of bona-fide Compact Symmetric Objects (CSOs) to investigate their X-ray emission properties. Ultimately, we obtain 32 effective X-ray observational spectra from 17 CSOs. Most spectra can be well described by an absorbed single power-law model, with the exception of six spectra requiring an additional component in the soft X-ray band and two spectra exhibiting an iron emission line component. The data analysis results unveil the diverse characteristics of X-ray emission from CSOs. The sample covers X-ray luminosity ranging within 10 40 −10 45 erg s −1 , intrinsic absorbing column density ( {N}_{{\rm{H}}}^{{\rm{int}}} ) ranging within 10 20 −10 23 cm −2 , and photon spectral index (Γ X ) ranging within 0.75–3.0. None of the CSOs in our sample have {N}_{{\rm{H}}}^{{\rm{int}}} > 10 23 cm −2 , indicating that the X-ray emission in these CSOs is not highly obscured. The distribution of Γ X for these CSOs closely resembles that observed in a sample of radio-loud quasars and low-excitation radio galaxies (RGs). In the radio–X-ray luminosity panel, these CSOs exhibit a distribution more akin to FR I RGs than FR II RGs, characterized by higher luminosities. The positive correlation between Γ X and the Eddington ratio, which has been noted in radio-quiet active galactic nuclei, is not observed in these CSOs. These findings suggest that although the contribution of the disk-corona system cannot be completely ruled out, jet/lobe radiation likely plays a dominant role in the X-ray emission of these CSOs.}, archive = {J_ApJ}, author = {Ying-Ying Gan and Su Yao and Tan-Zheng Wu and Hai-Ming Zhang and Jin Zhang}, doi = {10.3847/1538-4357/adb1e6}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {111}, shortjournal = {The Astrophys. J.}, title = {X-ray emission properties of a compact symmetric object sample}, volume = {981}, year = {2025}, }
• (2025). Building on the archives: Connecting the CN/CO intensity ratio with global galaxy properties in nearby U/LIRGs. ApJ, 981(2), 110. (www)

  @article{ , abstract = {We use the CN/CO intensity ratio to obtain the dense gas fraction, f dense , for a sample of 16 ultraluminous and luminous infrared (IR) galaxies and compare f dense with a suite of global galaxy properties. We find a significant correlation between f dense and star formation rate calculated using both IR luminosities and radio continuum, although there is significant scatter in each relation. We find no trend between global or peak f dense and merger stage. We find no correlation between global f dense and X-ray luminosity; however, the correlation becomes significant when we measure f dense at the location of peak X-ray emission. Our interpretation is that the dense gas is co-localized with strong X-ray emission from active galactic nuclei or strong central star formation.}, archive = {J_ApJ}, author = {Blake Ledger and Christine D. Wilson and Osvald Klimi and Núria Torres-Albà and Toshiki Saito}, doi = {10.3847/1538-4357/adb310}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {110}, shortjournal = {The Astrophys. J.}, title = {Building on the archives: Connecting the CN/CO intensity ratio with global galaxy properties in nearby U/LIRGs}, volume = {981}, year = {2025}, }
• (2025). Expansion-induced three-part morphology of the 2021 december 4 coronal mass ejection. ApJ, 981(2), 109. (www)

  @article{ , abstract = {The typical structure of a coronal mass ejection (CME) was identified as a three-part morphology, which includes a bright front, a dark cavity, and a bright core, with the cavity and the core generally regarded as flux rope and eruptive prominence. However, there are three-part CMEs that are not associated with prominences. In this work, we conduct a high-resolution simulation of the 2021 December 4 CME mimicked with a spheromak flux rope to investigate the formation of the three-part morphology in the solar corona. The CME, with no signatures of prominence at the beginning, evolves into a high–low–high-density structure, which appears in a coronagraph image as a bright front immediately followed by a dark cavity with a bright core behind. The moving and expanding spheromak flux rope sweeps up the solar wind plasma and meanwhile, the plasma at its utmost edge is compressed, which produces the high-density front overlying the flux rope. It is also found that the expansion of the flux rope is uneven, with strong expansion at its outlying area and weak expansion at its central and rear parts. The differential expansion rates lead to the distinct rarefaction rates of the plasma, which results in the formation of the low-density cavity and the high-density core within the flux rope. Our three-dimensional study for the first time demonstrates that the evolution of the flux rope can self-consistently generate the three-part density structure, which improves the understanding of CME's morphologies in coronagraph images.}, archive = {J_ApJ}, author = {Liping Yang and Xueshang Feng and Fang Shen and Ming Xiong and Chenglong Shen and Yutian Chi and Yuming Wang and Kuo Yan and Mengxuan Ma and Yufen Zhou and Man Zhang and Xinhua Zhao}, doi = {10.3847/1538-4357/adb313}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {109}, shortjournal = {The Astrophys. J.}, title = {Expansion-induced three-part morphology of the 2021 december 4 coronal mass ejection}, volume = {981}, year = {2025}, }
• (2025). Why artificial disruption is not a concern for current cosmological simulations. ApJ, 981(2), 108. (www)

  @article{ , abstract = {Recent studies suggest that cold dark matter subhalos are hard to disrupt and almost all cases of subhalo disruption observed in numerical simulations are due to numerical effects. However, these findings primarily relied on idealized numerical experiments, which do not fully capture the realistic conditions of subhalo evolution within a hierarchical cosmological context. Based on the Aquarius simulations, we identify clear segregation in the population of surviving and disrupted subhalos, which corresponds to two distinct acquisition channels of subhalos. We find that all of the first-order subhalos accreted after redshift 2 survive to the present time without suffering from artificial disruption. On the other hand, most of the disrupted subhalos are sub-subhalos accreted at high redshift. Unlike the first-order subhalos, sub-subhalos experience preprocessing and many of them are accreted through major mergers at high redshift, resulting in very high mass loss rates. We confirm these high mass loss rates are physical through both numerical experiments and semianalytical modeling, thus supporting a physical origin for their rapid disappearance in the simulation. Even though we cannot verify whether these subhalos have fully disrupted or not, their extreme mass loss rates dictate that they can at most contribute a negligible fraction to the very low mass end of the subhalo mass function. We thus conclude that current state-of-the-art cosmological simulations have reliably resolved the subhalo population.}, archive = {J_ApJ}, author = {Feihong He and Jiaxin Han and Zhaozhou Li}, doi = {10.3847/1538-4357/adb383}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {108}, shortjournal = {The Astrophys. J.}, title = {Why artificial disruption is not a concern for current cosmological simulations}, volume = {981}, year = {2025}, }
• (2025). Source materials and heating of alfvénic slow and hot solar wind revealed by heavy ions. ApJ, 981(2), 107. (www)

  @article{ , abstract = {This work quantitatively studies the differences of heavy ions among non-Alfvénic slow wind (N-ASSW), classical fast wind (FSW), and Alfvénic slow and hot wind (ASSW and AHSW) by effect size and Kolmogorov–Smirnov statistic. Statistics of ACE measurements in solar cycle 23 show that He/O and Fe/O in ASSW and AHSW are significantly similar to those in N-ASSW, but are distinct from FSW. The mean Fe 16+ /Fe 13+ in ASSW (AHSW) is in the middle of the two mean values of FSW and N-ASSW. However, Fe 16+ /Fe 13+ in the three categories of solar wind are similarly low during solar minimum. Charges of C and O ions in ASSW and AHSW are significantly different from those in FSW during solar minimum, but have obvious overlaps to those in FSW during solar maximum. Besides, the speed ratio of He 2+ , C 5+ , O 6+ , and Fe 10+ against protons is studied, and that of O 6+ in ASSW and AHSW is most like that in FSW. AHSW has two peaks of proton specific entropy showing negative and positive relations to electron temperature. The results support that ASSW, AHSW, and N-ASSW experience the same fractionation in the chromosphere. The heating in ASSW (AHSW) differs from N-ASSW between the freeze-in heights of O and Fe during solar maximum, possibly caused by interchange reconnection. The preferential acceleration of heavy ions may be proportional to the gyroradius scale. Dissipation of Alfvén waves to electrons may happen in AHSW.}, archive = {J_ApJ}, author = {Shuyi Meng and Shuo Yao}, doi = {10.3847/1538-4357/adb420}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {107}, shortjournal = {The Astrophys. J.}, title = {Source materials and heating of alfvénic slow and hot solar wind revealed by heavy ions}, volume = {981}, year = {2025}, }
• (2025). A planet candidate orbiting near the hot jupiter TOI-2818 b inferred through transit timing. ApJ, 981(2), 106. (www)

  @article{ , abstract = {TOI-2818 b is a hot Jupiter orbiting a slightly evolved G-type star on a 4.04 day orbit that shows transit timing variations (TTVs) suggestive of a decreasing orbital period. In the most recent year of TESS observations, transits were observed ∼8 minutes earlier than expected for a constant period. The implied orbital decay rate is 1.35 ± 0.25 s yr −1 , too fast to be explained by tidal dissipation, even considering the evolved nature of the host star. Radial velocity (RV) monitoring and astrometric data make the possibility of perturbations from a long-period companion unlikely; further Doppler spectroscopy observations can efficiently confirm or rule out such a companion. Apsidal precession due to the tidal distortion of the planet is also physically implausible. The most plausible explanation for the TTVs appears to be gravitational perturbations from a hitherto undetected planet with mass ≲10 M ⊕ that is in (or near) a mean-motion resonance with the hot Jupiter. Such a planet could be responsible for the observed TTVs while avoiding detection with the available RV and transit data.}, archive = {J_ApJ}, author = {Brendan J. McKee and Benjamin T. Montet and Samuel W. Yee and Joel D. Hartman and Joshua N. Winn and Jorge H. C. Martins and André M. Silva and Alexander L. Wallace}, doi = {10.3847/1538-4357/adac63}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {106}, shortjournal = {The Astrophys. J.}, title = {A planet candidate orbiting near the hot jupiter TOI-2818 b inferred through transit timing}, volume = {981}, year = {2025}, }
• (2025). Spatially resolved galactic winds at cosmic noon: Outflow kinematics and mass loading in a lensed star-forming galaxy at z = 1.87. ApJ, 981(2), 105. (www)

  @article{ , abstract = {We study the spatially resolved outflow properties of CSWA13, an intermediate-mass ( M * = 10 9 M ⊙ ), gravitationally lensed star-forming galaxy at z = 1.87. We use Keck/KCWI to map outflows in multiple rest-frame UV interstellar medium (ISM) absorption lines, along with fluorescent Si ii * emission, and nebular emission from C iii ] tracing the local systemic velocity. The spatial structure of the outflow velocity mirrors that of the nebular kinematics, which we interpret to be a signature of a young galactic wind that is pressurizing the ISM of the galaxy but is yet to burst out. From the radial extent of Si ii * emission, we estimate that the outflow is largely encapsulated within 3.5 kpc. We explore the geometry (e.g., patchiness) of the outflow by measuring the covering fraction at different velocities, finding that the maximum covering fraction is at velocities v ≃ −150 km s −1 . Using the outflow velocity ( v out ), radius ( R ), column density ( N ), and solid angle (Ω) based on the covering fraction, we measure the mass-loss rate \mathrm{log}{\dot{m}}_{\mathrm{out}}/({M}_{\odot }{\,\rm{yr}\,}^{-1})=1.73\pm 0.23 and mass loading factor \mathrm{log}\eta =0.04\pm 0.34 for the low-ionization outflowing gas in this galaxy. These values are relatively large and the bulk of the outflowing gas is moving with speeds less than the escape velocity of the galaxy halo, suggesting that the majority of the outflowing mass will remain in the circumgalactic medium and/or recycle back into the galaxy. The results support a picture of high outflow rates transporting mass and metals into the inner circumgalactic medium, providing the gas reservoir for future star formation.}, archive = {J_ApJ}, author = {Keerthi Vasan G. C. and Tucker Jones and Anowar J. Shajib and Sunny Rhoades and Yuguang Chen and Ryan L. Sanders and Daniel P. Stark and Richard S. Ellis and Nicha Leethochawalit and Glenn G. Kacprzak and Tania M. Barone and Karl Glazebrook and Kim-Vy H. Tran and Hannah Skobe and Kris Mortensen and Ivana Barisic}, doi = {10.3847/1538-4357/ada95b}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {105}, shortjournal = {The Astrophys. J.}, title = {Spatially resolved galactic winds at cosmic noon: Outflow kinematics and mass loading in a lensed star-forming galaxy at z = 1.87}, volume = {981}, year = {2025}, }
• (2025). Searching for low-redshift hot dust-obscured galaxies. ApJ, 981(2), 104. (www)

  @article{ , abstract = {Hot dust-obscured galaxies (Hot DOGs), discovered by the "W1W2 dropout" selection at high redshifts ( z ∼ 2–4), are a rare population of hyperluminous obscured quasars. Their number density is comparable to similarly luminous type 1 quasars in the same redshift range, potentially representing a short, yet critical stage in galaxy evolution. The evolution in their number density toward low redshift, however, remains unclear as their selection function is heavily biased against objects at z ≲ 2. We combine data from the Wide-field Infrared Survey Explorer and Herschel archives to search for Hot DOGs at z < 0.5 based on their unique spectral energy distributions. We find 68 candidates, and spectroscopic observations confirm that 3 of them are at z < 0.5. For those three, we find their black hole accretion is close to the Eddington limit, with lower bolometric luminosities and black hole masses than those of higher- z Hot DOGs. Compared to high- z systems, these low- z systems are closer to the local relation between host galaxy stellar mass and black hole mass but still lie above it, and we discuss several possible scenarios for it. Finally, we also find the surface number density of z < 0.5 Hot DOGs is 2.4 × 10 −3 deg −2 , about an order of magnitude lower than high- z Hot DOGs but comparable to hyperluminous unobscured quasars in the same redshift range. These results further support the idea that Hot DOGs may be a transitional phase of galaxy evolution.}, archive = {J_ApJ}, author = {Guodong Li and Jingwen Wu and Chao-Wei Tsai and Daniel Stern and Roberto J. Assef and Peter R. M. Eisenhardt and Kevin McCarthy and Hyunsung D. Jun and Tanio Díaz-Santos and Andrew W. Blain and Trystan Lambert and Dejene Zewdie and Román Fernández Aranda and Cuihuan Li and Yao Wang and Zeyu Tan}, doi = {10.3847/1538-4357/adabe3}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {104}, shortjournal = {The Astrophys. J.}, title = {Searching for low-redshift hot dust-obscured galaxies}, volume = {981}, year = {2025}, }
• (2025). Two 100 TeV neutrinos coincident with the seyfert galaxy NGC 7469. ApJ, 981(2), 103. (www)

  @article{ , abstract = {In 2013, the IceCube collaboration announced the detection of a diffuse high-energy astrophysical neutrino flux. The origin of this flux is still largely unknown. The most significant individual source is the close-by Seyfert galaxy NGC 1068 at the 4.2 σ level with a soft spectral index. To identify sources based on their counterpart, IceCube releases real-time alerts corresponding to neutrinos with a high probability of astrophysical origin. We report here the spatial coincidence of two neutrino alerts, IC 220424A and IC 230416A, with the Seyfert galaxy NGC 7469 at a distance of 70 Mpc. We evaluate, a posteriori, the chance probability of such a coincidence and discuss this source as a potential neutrino emitter based on its multiwavelength properties and in comparison to NGC 1068 by performing a goodness-of-fit test. A test statistic is derived from a likelihood ratio that includes the neutrino angular uncertainty and the source distance. We apply this test first to a catalog of active galactic nucleus sources and second to a catalog of Seyfert galaxies only. Our a posteriori evaluation excludes the possibility of an accidental spatial coincidence of both neutrinos with the Seyfert galaxy NGC 7469 at the 3.2 σ level, leaving open the possibility that either one or both neutrinos originated from the source. To be compatible with nondetections of TeV neutrinos, the source would need to have a hard spectral index.}, archive = {J_ApJ}, author = {Giacomo Sommani and Anna Franckowiak and Massimiliano Lincetto and Ralf-Jürgen Dettmar}, doi = {10.3847/1538-4357/adb031}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {103}, shortjournal = {The Astrophys. J.}, title = {Two 100 TeV neutrinos coincident with the seyfert galaxy NGC 7469}, volume = {981}, year = {2025}, }
• (2025). Mapping our path through the local interstellar medium: High-resolution ultraviolet absorption spectroscopy of sight lines along the sun’s historical trajectory. ApJ, 981(2), 102. (www)

  @article{ , abstract = {Using high-resolution UV data obtained from the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope, we focus on eight sight lines along the Sun's historical trajectory to reconstruct the morphology of our most recent interstellar environment and evaluate its effects on the Sun's heliosphere over the past five million years. Of the eight targets (each within 50 pc), we detect interstellar absorption in six, primarily Mg ii and Fe ii . We observe C ii and O i absorption in target HD 32147. In each analyzed sight line, the Local Interstellar Cloud (LIC) is observed and bears a similar column density. We detected the Blue and Aur clouds, both of which the Sun may have encountered before entering the LIC. In at least one sight line a fourth cloud is detected. Even in this compact sample, we observe variation in absorption across neighboring sight lines, reflecting the complexity of local interstellar medium (ISM) small-scale structure. We report the discovery of an astrosphere around target GJ J173, observable due to excess Ly α absorption caused by interaction between the star's stellar wind and the ISM. Over the past ∼five million years, the Sun spent the majority of the time in a low-density plasma region. We see no evidence of any cold, dense material along the observed sight lines. We present timelines for heliospheric response assuming a range of plausible hydrogen densities (0.1 and 0.2 cm −3 ). In both cases, we see the Sun, and the heliosphere, traversing significant density variations in its most recent past and most immediate future.}, archive = {J_ApJ}, author = {Hunter Vannier and Seth Redfield and Brian E. Wood and Hans-Reinhard Müller and Jeffrey L. Linsky and Priscilla C. Frisch}, doi = {10.3847/1538-4357/adb033}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {102}, shortjournal = {The Astrophys. J.}, title = {Mapping our path through the local interstellar medium: High-resolution ultraviolet absorption spectroscopy of sight lines along the sun’s historical trajectory}, volume = {981}, year = {2025}, }
• (2025). Estimating black hole masses in obscured active galactic nuclei from X-ray and optical emission line luminosities. ApJ, 981(2), 101. (www)

  @article{ , abstract = {We test a novel method for estimating black hole masses ( M BH ) in obscured active galactic nuclei (AGN) that uses proxies to measure the FWHM of broad H α (FWHM bH α ) and the accretion disk luminosity at 5100 Å ( λL 5100 Å ). Using a published correlation, we estimate FWHM bH α from the narrow optical emission line ratio L [O iii ] / L nH β . Using a sample of 99 local obscured AGN from the Swift Burst Alert Telescope AGN Spectroscopic Survey (BASS), we assess the agreement between estimating λL 5100 Å from the intrinsic 2 to 10 keV X-ray luminosity and from narrow optical emission lines. We find a mean offset of 0.32 ± 0.68 dex between these methods, which propagates to a factor of ∼2 uncertainty when estimating M BH using a virial mass formula where L [O iii ] / L nH β serves as a proxy of FWHM bH α ( M BH,[O iii ]/nH β ). We compare M BH,[O iii ]/nH β with virial M BH measurements from broad Paschen emission lines. For the 14 (12) BASS AGN with broad Pa α (Pa β ) detections, we find M BH,[O iii ]/nH β to be systematically higher than M BH,Pa α ( M BH,Pa β ) by a factor of 0.39 ± 0.44 dex (0.48 ± 0.51 dex). Since these offsets are within the scatter, more data are needed to assess whether M BH,[O iii ]/nH β is biased high. For 151 BASS AGN with measured stellar velocity dispersions ( σ * ), we find that the σ * -derived M BH agrees with M BH,[O iii ]/nH β to within 0.08 dex, albeit with wide scatter (0.74 dex). The method tested here can provide estimates of M BH in thousands of obscured AGN in spectroscopic surveys when other diagnostics are not available, though with an uncertainty of ∼3–5.}, archive = {J_ApJ}, author = {Stephanie LaMassa and Isabella Farrow and C. Megan Urry and Benny Trakhtenbrot and Connor Auge and Michael J. Koss and Alessandro Peca and Dave Sanders and Tracey Jane Turner}, doi = {10.3847/1538-4357/adb0bf}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {101}, shortjournal = {The Astrophys. J.}, title = {Estimating black hole masses in obscured active galactic nuclei from X-ray and optical emission line luminosities}, volume = {981}, year = {2025}, }
• (2025). A new X-ray census of rotation powered pulsars. ApJ, 981(2), 100. (www)

  @article{ , abstract = {To date, over 4000 pulsars have been detected. In this study, we identify 231 X-ray counterparts of Australia Telescope National Facility (ATNF) pulsars by performing a spatial cross match across the Chandra, XMM-Newton observational catalogs. This data set represents the largest sample of X-ray counterparts ever compiled, including 98 normal pulsars (NPs) and 133 millisecond pulsars (MSPs). Based on this significantly expanded sample, we re-establish the correlation between X-ray luminosity and spin-down power, given by {L}_{{\rm{X}}}\propto {\dot{E}}^{0.85\pm 0.05} across the whole X-ray band. The strong correlation is also observed in hard X-ray band, while in soft X-ray band there is no significant correlation. Furthermore, L X shows a strong correlation with spin period and characteristic age for NPs. For the first time, we observe a strongly positive correlation between L X and the light cylinder magnetic field ( B lc ) for MSPs, with both NPs and MSPs following the relationship {L}_{{\rm{X}}}\propto {B}_{{\rm{lc}}}^{1.14} , consistent with the outer-gap model of pulsars that explains the mechanism of X-ray emission. Additionally, we investigate potential X-ray counterparts for Galactic Plane Pulsar Snapshot pulsars, finding a lower likelihood of detection compared to ATNF pulsars.}, archive = {J_ApJ}, author = {Yu-Jing Xu and Han-Long Peng and Shan-Shan Weng and Xiao Zhang and Ming-Yu Ge}, doi = {10.3847/1538-4357/adaebc}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {100}, shortjournal = {The Astrophys. J.}, title = {A new X-ray census of rotation powered pulsars}, volume = {981}, year = {2025}, }
• (2025). PSR j1231–1411 revisited: Pulse profile analysis of X-ray observation. ApJ, 981(2), 99. (www)

  @article{ , abstract = {One of the primary goals of Neutron Star Interior Composition Explorer (NICER)-like X-ray missions is to impose stringent constraints on the neutron star equation of state by precisely measuring their masses and radii. NICER has recently expanded the data set of inferred mass–radius relations for neutron stars, including four rotation-powered millisecond pulsars PSR J0030+0451, PSR J0740+6620, PSR J0437–4715, and PSR J1231–1411. In this work, the mass–radius relation and X-ray emitting region properties of PSR J1231–1411 are inferred with an independent pulse profile modeling based on the spherical star Schwarzschild spacetime and Doppler approximation. With one single-temperature elongated hot spot and one single-temperature crescent hot spot, the inferred gravitational mass is M = 1.12 ± 0.07 M ⊙ and the inferred equatorial radius is {R}_{{\rm{eq}}}=9.9{1}_{-0.86}^{+0.88} km (68% credible intervals). It provides an alternative geometry configuration of the X-ray emitting region for PSR J1231–1411 to sufficiently explain the observation data of NICER and XMM-Newton. The inferred radius is smaller than that derived by T. Salmi et al. ( M=1.0{4}_{-0.03}^{+0.05} M ⊙ , R eq = 12.6 ± 0.3 km), and the inferred mass is slightly higher in this work. The inferred geometry configurations of the X-ray emitting region in both works are nonantipodal, which is not consistent with a centered dipole magnetic field and suggests a complex magnetic field structure.}, archive = {J_ApJ}, author = {Liqiang Qi and Shijie Zheng and Juan Zhang and Mingyu Ge and Ang Li and Shuang-Nan Zhang and Fangjun Lu and Hanlong Peng and Liang Zhang and Hua Feng and Zhen Zhang and Yupeng Xu and Zhengwei Li and Liming Song and Shu Zhang and Lian Tao and Wentao Ye}, doi = {10.3847/1538-4357/adb42f}, journal = {The Astrophysical Journal}, month = {3}, number = {2}, pages = {99}, shortjournal = {The Astrophys. J.}, title = {PSR j1231–1411 revisited: Pulse profile analysis of X-ray observation}, volume = {981}, year = {2025}, }
• (2025). Habitability in 4D: Predicting the climates of earth analogs across rotation and orbital configurations. ApJ, 981(1), 98. (www)

  @article{ , abstract = {Earth-like planets in the circumstellar habitable zone (HZ) may have dramatically different climate outcomes depending on their spin–orbit parameters, altering their habitability for life as we know it. We present a suite of 93 ROCKE-3D general circulation models (GCMs) for planets with the same surface conditions and average annual insolation as Earth, but with a wide range of rotation periods, obliquities, orbital eccentricities, and longitudes of periastra. Our habitability metric f HZ is calculated based on the temperature and precipitation in each model across grid cells over land. Latin hypercube sampling aids in sampling all four of the spin–orbit parameters with a computationally feasible number of GCM runs. Statistical emulation then allows us to model f HZ as a smooth function with built-in estimates of statistical uncertainty. We fit our emulator to an initial set of 46 training runs, then test with an additional 46 runs at different spin–orbit values. Our emulator predicts the directly GCM-modeled habitability values for the test runs at the appropriate level of accuracy and precision. For orbital eccentricities up to 0.225, rotation period remains the primary driver of the fraction of land that remains above freezing and with precipitation above a threshold value. For rotation periods greater than ~20 days, habitability drops significantly (from ~70% to ~20%), driven primarily by cooler land temperatures. Obliquity is a significant secondary factor for rotation periods less than ~20 Earth days, with a factor of 2 impact on habitability that is maximized at intermediate obliquity.}, archive = {J_ApJ}, author = {Arthur D. Adams and Christopher Colose and Aronne Merrelli and Margaret Turnbull and Stephen R. Kane}, doi = {10.3847/1538-4357/ada3c8}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {98}, shortjournal = {The Astrophys. J.}, title = {Habitability in 4D: Predicting the climates of earth analogs across rotation and orbital configurations}, volume = {981}, year = {2025}, }
• (2025). Supernova siblings and spectroscopic host galaxy properties. ApJ, 981(1), 97. (www)

  @article{ , abstract = {Over the past century, supernova (SN) searches have detected multiple supernovae (SNe) in hundreds of individual galaxies. So-called SN siblings discovered in the same galaxy present an opportunity to constrain the dependence of the properties of SNe on those of their host galaxies. To investigate whether there is a connection between sibling SNe in galaxies that have hosted multiple SNe and the properties of galaxies, we have acquired integrated optical spectroscopy of 59 galaxies with multiple core-collapse SNe. Perhaps surprisingly, a strong majority of host galaxy spectra fall within the composite region of the Baldwin–Phillips–Terlevich (BPT) diagram. We find a statistically significant difference (Kolmogorov–Smirnov test p -value = 0.044) between the distributions of the [N ii ] λ 6583/H α of galaxies that have hosted a majority of SNe Ibc and those that have hosted a majority of Type II supernovae (SNe II), where the majority of Type Ibc supernovae (SNe Ibc) galaxies have, on average, higher ratios. The difference between the distributions of [N ii ] λ 6583/H α may arise from either increased contribution from active galactic nuclei or low-ionization nuclear emission-line regions in SNe Ibc host galaxies, greater metallicity for SNe Ibc host galaxies, or both. When comparing the inferred oxygen abundance and the ionization parameter for the galaxies in the star-forming region on the BPT diagram, we find statistically significant differences between the distributions for SNe Ibc hosts and SNe II hosts ( p = 0.008 and p = 0.001, respectively), as well as SNe Ib hosts and SNe II hosts ( p = 0.030 and p = 0.006, respectively). We also compare the H α equivalent width distributions, also integrated across the galaxies, and find no significant difference.}, archive = {J_ApJ}, author = {Laura Salo and Rui Zhou and Samuel Johnson and Patrick Kelly and Galin L. Jones}, doi = {10.3847/1538-4357/adad60}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {97}, shortjournal = {The Astrophys. J.}, title = {Supernova siblings and spectroscopic host galaxy properties}, volume = {981}, year = {2025}, }
• (2025). Compact [O iii] emission-line regions (“Green seeds”) in hα emitters at cosmic noon from JWST observations. ApJ, 981(1), 96. (www)

  @article{ , abstract = {We present a rest-frame optical, spatially resolved analysis of more than 100 H α emitters (HAEs) at z ∼ 2.2 in the ZFOURGE-CDFS field using NIRCam imaging from the JWST Advanced Deep Extragalactic Survey. The ultradeep, high-resolution data give us maps of the resolved emission-line regions of HAEs with stellar mass ranging from 10 8 M ⊙ to 10 10 M ⊙ . An [O iii ] emission-line map of each HAE is created from the flux excess in the F150W filter, leading to the discovery of a population of kiloparsec-scale compact emission-line regions ("Green Seeds") with high equivalent widths (EW). We obtain a sample of 128 Green Seeds from 68 HAEs with rest-frame EW [O III] > 200 Å. Moreover, 17 of them have extremely large EW [O III] > 1000 Å, suggesting the possible Lyman continuum leakage from these emission-line regions. Embedded within the host galaxy, many Green Seeds correspond to UV star-forming clumps and H ii regions, indicating elevated starburst activity in them, with specific star formation rates several times higher than that of the host galaxy. Based on theoretical frameworks, Green Seeds are expected to be formed through gravitational disk instability and/or galaxy mergers. Considering the stellar masses of Green Seeds, we speculate that high-mass Green Seeds may migrate toward the galactic center to build the central bulge, while low-mass Green Seeds are easily disrupted and short lived. Besides, we propose that some Green Seeds could be the progenitors of globular clusters or ultracompact dwarf galaxies observed in the local Universe.}, archive = {J_ApJ}, author = {Nuo Chen and Kentaro Motohara and Lee Spitler and Matthew A. Malkan}, doi = {10.3847/1538-4357/adad69}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {96}, shortjournal = {The Astrophys. J.}, title = {Compact [O iii] emission-line regions (“Green seeds”) in hα emitters at cosmic noon from JWST observations}, volume = {981}, year = {2025}, }
• (2025). HH 270/110 as a Jet/Shear layer interaction. ApJ, 981(1), 95. (www)

  @article{ , abstract = {New observations obtained with JWST of the protostellar HH 270 jet and the "deflected" HH 110 system show that HH 110 has a morphology of a series of distorted working surfaces. These working surfaces appear to be "deflected versions" of the heads of the incident HH 270 jet. We compute a series of 3D numerical simulations, in which we explore the possible parameters of a shearing environment that could give rise to the deflection of HH 270 into the HH 110 flow. We find that we need quite a high sideways velocity for the streaming environment (∼30 km s −1 ) in order to produce the complex structure observed in HH 110. This high velocity would be possible in an environment that has been strongly perturbed by the passage of other outflows.}, archive = {J_ApJ}, author = {A. C. Raga and A. Noriega-Crespo and A. Castellanos-Ramírez and J. Cantó and H. Arce and M. Lebrón and J. L. Morales Ortiz and A. N. Ortiz Capeles and C. A. Pantoja}, doi = {10.3847/1538-4357/adad6d}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {95}, shortjournal = {The Astrophys. J.}, title = {HH 270/110 as a Jet/Shear layer interaction}, volume = {981}, year = {2025}, }
• (2025). Hidden in plain sight: Searching for dark companions to bright stars with the large binocular telescope and SHARK-VIS. ApJ, 981(1), 94. (www)

  @article{ , abstract = {We report the results from a pilot study to search for black holes and other dark companions in binary systems using direct imaging with SHARK-VIS and the iLocater pathfinder "Lili" on the Large Binocular Telescope. Starting from known single-lined spectroscopic binaries, we select systems with high mass functions that could host dark companions and whose spectroscopic orbits indicate a projected orbital separation ≥30 mas. For this first exploration, we selected four systems (HD 137909, HD 104438, HD 117044, and HD 176695). In each case, we identify a luminous companion and measure the flux ratio and angular separation. However, two of the systems (HD 104438 and HD 176695) are not consistent with simple binary systems and are most likely hierarchical triples. The observed companions rule out a massive compact object for HD 137909, HD 117044, and HD 176695. HD 104438 requires further study because the identified star cannot be responsible for the RV orbit and is likely a dwarf tertiary companion. The SHARK-VIS observation was taken near pericenter, and a second image near apocenter is needed to discriminate between a closely separated luminous secondary and a compact object. When a luminous companion is found, the combination of the RVs and the single SHARK-VIS observation strongly constrains the orbital inclination and the companion mass. Since a single SHARK-VIS observation has a typical on-source observing time of only ∼10 minutes, this a promising method to efficiently identify non-interacting compact object candidates.}, archive = {J_ApJ}, author = {D. M. Rowan and T. A. Thompson and C. S. Kochanek and G. Li Causi and J. Roth and P. Vaccari and F. Pedichini and R. Piazzesi and S. Antoniucci and V. Testa and M. C. Johnson and J. Crass and J. R. Crepp and A. Bechter and E. B. Bechter and B. L. Sands and R. J. Harris and B. J. Fulton}, doi = {10.3847/1538-4357/adad6e}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {94}, shortjournal = {The Astrophys. J.}, title = {Hidden in plain sight: Searching for dark companions to bright stars with the large binocular telescope and SHARK-VIS}, volume = {981}, year = {2025}, }
• (2025). On the temporal variability of the galactic multi-TeV interstellar emissions. ApJ, 981(1), 93. (www)

  @article{ , abstract = {We use the GALPROP cosmic ray (CR) framework to model the Galactic CR distributions and associated nonthermal diffuse emissions up to PeV energies. We consider ensembles of discrete, finite lifetime CR sources, e.g., supernova remnants, for a range of creation rates and lifetimes. We find that the global properties of the CR sources are likely not directly recoverable from the current "snapshot" of the historic injection and propagation of CRs within the Galaxy that are provided by the data. We show that models for the diffuse γ rays based on the discrete/time-dependent scenarios we consider are able to explain the LHAASO very-/ultra-high-energy (VHE/UHE) γ -ray data with up to 50% contribution by unresolved leptonic sources at the highest energies. Over the models that we consider, variations in the diffuse VHE emissions can be ∼25%, which is comparable to those for the steady-state models that we investigated in an earlier work. Such variations due to the discrete/finite nature of the CR sources are an important factor that are necessary to construct accurate physical models of the diffuse emissions from the Galaxy at VHE/UHEs.}, archive = {J_ApJ}, author = {P. D. Marinos and T. A. Porter and G. P. Rowell and G. Jóhannesson and I. V. Moskalenko}, doi = {10.3847/1538-4357/adadfb}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {93}, shortjournal = {The Astrophys. J.}, title = {On the temporal variability of the galactic multi-TeV interstellar emissions}, volume = {981}, year = {2025}, }
• (2025). LIMFAST. III. timing cosmic reionization with the 21 cm and near-infrared backgrounds. ApJ, 981(1), 92. (www)

  @article{ , abstract = {The timeline of cosmic reionization remains uncertain despite sustained efforts to study how the ionizing output of early galaxies shaped the intergalactic medium (IGM). Using the seminumerical code LIMFAST, we investigate the prospects for timing the reionization process by cross-correlating the 21 cm signal with the cosmic near-infrared background (NIRB) contributed by galaxies at z > 5. Tracing opposite phases of the IGM on large scales during reionization, the two signals together serve as a powerful probe for the reionization history. However, because long-wavelength, line-of-sight Fourier modes—the only modes probed by NIRB fluctuations—are contaminated by 21 cm foregrounds and thus inevitably lost to foreground cleaning or avoidance, a direct cross correlation of the two signals vanishes. We show that this problem can be circumvented by squaring the foreground-filtered 21 cm signal and cross-correlating the squared field with the NIRB. This statistic is related to the 21 cm–21 cm–NIRB cross bispectrum and encodes valuable information regarding the reionization timeline. Particularly, the 21 cm 2 and NIRB signals are positively correlated during the early phases of reionization and negatively correlated at later stages. We demonstrate that this behavior is generic across several different reionization models and compare our simulated results with perturbative calculations. We show that this cross correlation can be detected at high significance by forthcoming 21 cm and NIRB surveys such as the Square Kilometre Array and SPHEREx. Our methodology is more broadly applicable to cross correlations between line intensity mapping data and 2D tracers of the large-scale structure, including photometric galaxy surveys and cosmic microwave background lensing mass maps, among others.}, archive = {J_ApJ}, author = {Guochao Sun and Adam Lidz and Tzu-Ching Chang and Jordan Mirocha and Steven R. Furlanetto}, doi = {10.3847/1538-4357/adae12}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {92}, shortjournal = {The Astrophys. J.}, title = {LIMFAST. III. timing cosmic reionization with the 21 cm and near-infrared backgrounds}, volume = {981}, year = {2025}, }
• (2025). Swift-XRT and NuSTAR monitoring of obscuration variability in mrk 477. ApJ, 981(1), 91. (www)

  @article{ , abstract = {We present the analysis of 15 X-ray observations of Mrk 477, a nearby Seyfert 2 active galactic nucleus, with the objective to monitor its obscuring column density variability. The full data set consists of five archival observations, split into two XMM-Newton, two NuSTAR and one Chandra observation, plus two dedicated monitoring campaigns. The monitoring campaigns were performed with Swift-XRT and NuSTAR, containing five observations each. We performed a simultaneous analysis using self-consistent torus models, deriving geometric properties of the torus as well as the obscuration along the line of sight. Mrk 477 is best modeled with a torus with a large covering factor yet low column density (on average). Its line-of-sight column density oscillates between 1.5 and 7 × 10 23 cm −2 . Mrk 477 presents frequent obscuring column density variability, on timescales as short as ∼2 weeks. The probability of drawing a pair of obscuration-variable observations for Mrk 477 when having two, three, and four observations is 40%, 78%, and 95%, respectively. Adding the results of this work to those of another 26 sources, we find a trend of increasing obscuration variability with time (from ∼20% at Δ t < 10 days, to ∼60%–70% at timescales larger than 5 yr). We discuss whether this is compatible with the majority of obscuration variability coming from broad-line region clouds.}, archive = {J_ApJ}, author = {N. Torres-Albà and Z. Hu and I. Cox and S. Marchesi and M. Ajello and A. Pizzetti and I. Pal and R. Silver and X. Zhao}, doi = {10.3847/1538-4357/adaf18}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {91}, shortjournal = {The Astrophys. J.}, title = {Swift-XRT and NuSTAR monitoring of obscuration variability in mrk 477}, volume = {981}, year = {2025}, }
• (2025). A central TDE candidate detected through spectroscopic continuum emission properties in an SDSS blue quasar. ApJ, 981(1), 90. (www)

  @article{ , abstract = {In this paper, properties of spectroscopic continuum emissions are considered to detect potential tidal disruption event (TDE) candidates among Sloan Digital Sky Survey (SDSS) quasars. After considering the simple blackbody photosphere model applied to describe quasar continuum emissions with parameters of blackbody temperature T BB and blackbody radius R BB , SDSS quasars and reported optical TDEs occupy distinct regions in the space of T BB and R BB . Then, through the dependence of R BB on T BB for SDSS quasars, 402 outliers in the SDSS Stripe 82 region can be collected. Among the 402 outliers, SDSS J2308 at z = 1.16 is mainly considered, due to its SDSS spectrum observed around the peak brightness of the light curves. With the 7.2 yr long light curves described by the theoretical TDE model, the determined T BB and R BB through its spectroscopic continuum emissions are consistent with the values determined by the TDE model, to support the central TDE. Moreover, considering simulated results on continuum emissions of SDSS quasars around z ∼ 1.16, it can be confirmed at a confidence level higher than 4 σ that the continuum emissions of SDSS J2308 are not related to normal quasars. Furthermore, through the simulated results by the accepted continuous autoregressive process to trace intrinsic active galactic nucleus variability, the confidence level higher than 3 σ can be confirmed that the long-term light curves of SDSS J2308 are related to a central TDE. The jointed probabilities through both spectroscopic and photometric simulations, the confidence level higher than 5 σ can be confirmed to support the central TDE in SDSS J2308.}, archive = {J_ApJ}, author = {XueGuang Zhang}, doi = {10.3847/1538-4357/adaf9c}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {90}, shortjournal = {The Astrophys. J.}, title = {A central TDE candidate detected through spectroscopic continuum emission properties in an SDSS blue quasar}, volume = {981}, year = {2025}, }
• (2025). Tidal formation of dark matter deficit diffuse galaxy NGC 1052-DF2 by SIDM. ApJ, 981(1), 89. (www)

  @article{ , abstract = {Observations have revealed a significant dark matter deficit in the ultradiffuse galaxy NGC 1052-DF2 (DF2). It is widely accepted that the formation of this unique galaxy can be attributed to the tidal stripping of its host galaxy, NGC 1052. In this study, we simulate the evolution of a satellite system containing globular clusters (GCs) within an accreting host halo in the framework of self-interacting dark matter (SIDM). Our simulation results suggest that the heightened tidal stripping resulting from dark matter (DM) self-interactions can give rise to the transformation of a conventional dwarf galaxy into a dark matter deficit galaxy resembling DF2. Furthermore, we demonstrate that a DF2 analog can also be produced on an orbit with a greater pericenter distance by increasing the strength of DM self-interactions. This suggests that the issue of extreme orbital parameters can be mitigated by implementing the SIDM model. The distributions of the GC population derived in our SIDM simulation are consistent with the observed characteristics of DF2. The potential for reproducing DF2 and its GC population in the cold dark matter scenario is also discussed.}, archive = {J_ApJ}, author = {Zhao-Chen Zhang and Xiao-Jun Bi and Peng-Fei Yin}, doi = {10.3847/1538-4357/adaf9d}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {89}, shortjournal = {The Astrophys. J.}, title = {Tidal formation of dark matter deficit diffuse galaxy NGC 1052-DF2 by SIDM}, volume = {981}, year = {2025}, }
• (2025). Discovery of weak CN stars in the large magellanic cloud and comparison to stellar models. ApJ, 981(1), 88. (www)

  @article{ , abstract = {The recent discovery that red supergiants in M31 and M33 contain a weak CN spectral absorption feature at ​​​​​​∼8000 Å prompted us to analyze a large CTIO 4 m Hydra spectral database of stars in the Large Magellanic Cloud (LMC). We find 751 confirmed weak CN stars in the LMC, present an overview of their spectral and photometric properties, and compare them with the weak CN stars in M31 and M33. We use a method for automatically identifying weak CN stars based on a spectral template and find that weak CN stars are almost exclusively short-lived massive stars in the core He-burning evolutionary phase. We derive a mean main-sequence age of 40 Myr for these stars through a Bayesian approach to isochrone fitting that is consistent across all three galaxies. We then examine possible evolutionary processes and atmospheric conditions that could lead to weak CN stars using a suite of low-resolution model spectra. We find a preferred range of values for T eff and log g in O-rich stars that would result in the CN absorption and also speculate that this feature could arise due to the N enhancement expected in fast-rotating stars, though more targeted modeling is required.}, archive = {J_ApJ}, author = {Douglas Grion Filho and Puragra Guhathakurta and Stanley M. Rinehart and Leo Girardi and Paola Marigo and Antara R. Bhattacharya and Knut Olsen}, doi = {10.3847/1538-4357/adb030}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {88}, shortjournal = {The Astrophys. J.}, title = {Discovery of weak CN stars in the large magellanic cloud and comparison to stellar models}, volume = {981}, year = {2025}, }
• (2025). Cataloging stream interaction regions at MAVEN: A cross-comparative study with STEREO-A. ApJ, 981(1), 87. (www)

  @article{ , abstract = {Stream interaction regions (SIRs) are long-lasting solar wind structures that result from stable fast solar wind interacting with preceding slow solar wind. These structures have been examined in depth throughout the heliosphere, particularly at 1 au; however, due to sparse observations, SIRs have not been characterized thoroughly at 1.5 au. Thanks to the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission, we have a chance to fill this observational gap. We implement in situ solar wind data collected by MAVEN to identify SIRs between 2014 November and 2023 September. We observe 185 SIRs with average durations of 2.2 days that occur primarily during periods of low solar activity. We detect 19 forward shocks, seven reverse shocks, and one shock pair within these 185 SIRs. We predict a total SIR-associated shock detection rate of ∼56% at 1.5 au and compare this rate to previous findings spanning 0.1–5 au. We examine Solar Terrestrial Relations Observatory (STEREO) A data at 1 au to cross-compare with our results at 1.5 au. We determine the magnetic compression ratios ( H ) associated with SIRs at MAVEN and STEREO-A and find that H is ∼18% higher at 1.5 au than 1 au. We find that for a given SIR observed at both 1 and 1.5 au, H is ∼32% higher at 1.5 au. We also do not see a stark difference in the change in H for SIRs observed at both STEREO-A and MAVEN with respect to the angular separation of the spacecraft.}, archive = {J_ApJ}, author = {Sarah A. Henderson and Rachael J. Filwett and Robert C. Allen and Christina O. Lee and Jasper S. Halekas and Jared R. Espley and Antoinette Galvin and Hanying Wei}, doi = {10.3847/1538-4357/adb03b}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {87}, shortjournal = {The Astrophys. J.}, title = {Cataloging stream interaction regions at MAVEN: A cross-comparative study with STEREO-A}, volume = {981}, year = {2025}, }
• (2025). Investigating the effects of atmospheric stratification on coronal active region field modeling. ApJ, 981(1), 86. (www)

  @article{ , abstract = {Understanding the evolution of the complex magnetic fields found in solar active regions is an active area of research. There exist many different models for such fields, which range in their complexity due to the number of physical effects included in them—one common factor being that they all extrapolate the field up from the photosphere. In this study, we focus on the fact that above the photosphere and below the corona lies the relatively cool and dense chromosphere—which is often neglected in coronal models, due to it being comparatively thin and difficult to model. We isolate and examine the effect including this boundary layer has on a 2.5D class of driven MHD models of an active region eruption. We find that it can result in significant changes to the dynamics of an erupting field far higher in the atmosphere than the chromosphere itself, generally delaying eruptions and increasing the magnetic energy released in each eruption. We also test whether these effects can be approximated using a variation of the more computationally efficient magnetofrictional model, finding a number of simple adaptations of the standard magnetofrictional model, which capture the effect of the chromospheric stratification well.}, archive = {J_ApJ}, author = {Oliver Rice and Christopher Prior}, doi = {10.3847/1538-4357/adb1ae}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {86}, shortjournal = {The Astrophys. J.}, title = {Investigating the effects of atmospheric stratification on coronal active region field modeling}, volume = {981}, year = {2025}, }
• (2025). Spectra of he isotopes and the 3He/4He ratio. ApJ, 981(1), 85. (www)

  @article{ , abstract = {Since its launch, the Alpha Magnetic Spectrometer-02 (AMS-02) has delivered outstanding quality measurements of the spectra of cosmic-ray (CR) species, e ± , \bar{p} , and nuclei (H–Si, S, Fe), which have resulted in a number of breakthroughs. Besides elemental spectra, AMS-02 also measures the spectra of light isotopes albeit within a smaller rigidity range. In this paper, we use the precise measurements of He isotopes and the 3 He/ 4 He ratio by AMS-02, together with Voyager 1 data, and investigate their origin. We show that there is an excess in 3 He at higher energies compared to standard calculations assuming its fully secondary origin, which may indicate a source of primary 3 He, or signify a change in the propagation parameters over the Galactic volume probed by the 3 He/ 4 He ratio. We provide updated local interstellar spectra (LIS) of 3 He and 4 He in the rigidity range from 2 to 40 GV. Our calculations employ the self-consistent G al P rop –H el M od framework that has proved to be a reliable tool in deriving the LIS of CR e − , \bar{p} , and nuclei Z ≤ 28.}, archive = {J_ApJ}, author = {M. J. Boschini and S. Della Torre and M. Gervasi and D. Grandi and G. Jóhannesson and G. La Vacca and N. Masi and I. V. Moskalenko and S. Pensotti and T. A. Porter and L. Quadrani and P. G. Rancoita and D. Rozza and M. Tacconi}, doi = {10.3847/1538-4357/adb288}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {85}, shortjournal = {The Astrophys. J.}, title = {Spectra of he isotopes and the 3He/4He ratio}, volume = {981}, year = {2025}, }
• (2025). Neutrinos from carbon-burning red supergiants and their detectability. ApJ, 981(1), 84. (www)

  @article{ , abstract = {Stars emit megaelectronvolt neutrinos during their evolution via nuclear syntheses and thermal processes, and detecting them could provide insights into stellar structure beyond what is accessible through electromagnetic wave observations. So far, megaelectronvolt neutrinos have been observed from the Sun and SN 1987A. It has been suggested that pre-supernova stars in the oxygen- and silicon-burning stages would emit enough megaelectronvolt neutrinos to be detectable on Earth, provided they are in the local Universe. In this study, we investigate the prospect of detecting neutrinos from red supergiants (RSGs) in the carbon-burning phase. In our Galaxy, around a thousand RSGs have been cataloged, and several are expected to be in the carbon-burning phase. We first calculate the luminosity and energy spectrum of the neutrinos emitted during the post-main-sequence evolution of massive stars. For a nearby carbon-burning RSG located  ∼200 pc away, we estimate the neutrino flux reaching Earth to be as large as  ∼10 5 cm −2 s −1 , with a spectrum peaking at ∼0.6 MeV. We then assess the feasibility of detecting these neutrinos in underground facilities, particularly in hybrid detectors equipped with a water-based liquid scintillator and ultrafast photodetectors. In detectors with a volume comparable to Super-Kamiokande, for the above flux, we anticipate up to  ∼50 neutrino events per year with directional information. Although this is a fair number, the number of events from radioactive backgrounds would be much larger. Our results indicate that studying neutrinos from carbon-burning RSGs and predicting supernovae well in advance before their explosion would be challenging with currently available detector technologies.}, archive = {J_ApJ}, author = {Gwangeon Seong and Kyujin Kwak and Dongsu Ryu and Bok-Kyun Shin}, doi = {10.3847/1538-4357/adb41f}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {84}, shortjournal = {The Astrophys. J.}, title = {Neutrinos from carbon-burning red supergiants and their detectability}, volume = {981}, year = {2025}, }
• (2025). Probing 3D magnetic fields using starlight polarization and grain alignment theory. ApJ, 981(1), 83. (www)

  @article{ , abstract = {Polarization of starlight induced by dust grains aligned with the magnetic field (hereafter B -field) is widely used to measure the 2D B -fields projected onto the plane-of-sky. Here, we introduce a new method to infer 3D B -fields using starlight polarization. We show that the inclination angle or line-of-sight component of B -fields can be constrained by the starlight polarization efficiency from observations, the alignment degree provided by the magnetically enhanced radiative torque (MRAT) alignment theory, and the effect of B -field tangling. We first perform synthetic observations of starlight polarization of magnetohydrodynamic (MHD) simulations of a filamentary cloud with our updated POLARIS code incorporating the modern MRAT theory. We test the new technique with synthetic observations and find that the B -field inclination angles can be accurately determined by the synthetic starlight polarization efficiency once the effects of grain alignment, dust properties, and B -field fluctuations are well characterized. The technique can provide an accurate constraint on B -field inclination angles using optical polarization in low-density regions A V < 3 with efficient MRAT alignment, whereas the technique can infer further to high-density regions with significant alignment loss at A V ∼ 8–30 by using near-infrared polarization. Our new technique unlocks the full potential of tracing 3D B -fields and constraining dust properties and grain alignment physics on multiple scales of the diffuse interstellar medium and star-forming regions using multiwavelength starlight polarization observations.}, archive = {J_ApJ}, author = {Bao Truong and Thiem Hoang}, doi = {10.3847/1538-4357/adb423}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {83}, shortjournal = {The Astrophys. J.}, title = {Probing 3D magnetic fields using starlight polarization and grain alignment theory}, volume = {981}, year = {2025}, }
• (2025). Parallel electric fields and electron heating observed in the young solar wind. ApJ, 981(1), 82. (www)

  @article{ , abstract = {The largest electric fields between 18 and 30 solar radii are in narrowband waves simultaneously observed at a few Hz (somewhat above the local proton gyrofrequency) and a few hundred Hz (far below the lower hybrid frequency), with the higher-frequency wave triggered at specific phases of the lower-frequency wave. This wave pair, called "triggered ion-acoustic waves" (TIAWs), has been shown to both be physical and to occur at times of electron heating. A theory of electron heating and acceleration by the low-frequency wave has been presented. While this theory and the TIAW results strongly suggest the presence of low-frequency electric fields that are parallel to the local magnetic field, such fields have not been directly observed. In this paper, such parallel electric field observations are reported, and TIAWs are further described to conclude that they occur during about 75% of the Parker Solar Probe passes through 18–30 solar radii, and when present, they are the dominant wave signal, lasting for hours. In the presence of these parallel electric fields, electrons are heated while, in their absence, there is no electron heating. That there is no heating between 18 and 30 solar radii in the absence of TIAWs is a most significant result because it invalidates other proposed mechanisms that predict heating in this radial range all of the time.}, archive = {J_ApJ}, author = {F. S. Mozer and O. V. Agapitov and K.-E. Choi and R. D. Sydora}, doi = {10.3847/1538-4357/adb582}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {82}, shortjournal = {The Astrophys. J.}, title = {Parallel electric fields and electron heating observed in the young solar wind}, volume = {981}, year = {2025}, }
• (2025). The circumgalactic medium traced by mg ii absorption with DESI: Dependence on galaxy stellar mass, star formation rate, and azimuthal angle. ApJ, 981(1), 81. (www)

  @article{ , abstract = {Understanding the circumgalactic medium (CGM) distribution of galaxies is the key to revealing the dynamical exchange of materials between galaxies and their surroundings. In this work, we use the DESI Early Data Release data set to investigate the cool CGM of galaxies (0.3 < z < 1.7) by stacking the spectra of background quasi-stellar objects to obtain the Mg ii absorption of foreground galaxies. The equivalent width of Mg ii absorption strongly correlates with stellar mass, with EW(Mg ii ) \propto {M}_{* }^{0.5} for star-forming galaxies with \mathrm{log}{M}_{* }/{M}_{\odot }\lt 10 , but is independent of mass for galaxies above this mass. At a given stellar mass, EW(Mg ii ) is larger for galaxies of higher star formation rate with an impact parameter less than 50 kpc, while showing little dependence on galaxy size. By studying the dependence on azimuthal angle, we find EW(Mg ii ) is strongest at the direction near the minor axis for star-forming galaxies with \mathrm{log}{M}_{* }/{M}_{\odot }\lt 10.0 , while no dependence on azimuthal angle is seen for luminous red galaxies. This indicates that the outflow associated with star formation enhances the Mg ii absorption. However, for galaxies with \mathrm{log}{M}_{* }/{M}_{\odot }\gt 10.0 , the EW(Mg ii ) at the minor axis is largely suppressed with respect to low-mass galaxies. This suggests that the competing processes, such as stellar feedback and gravity, play a key role in shaping the distribution of outflowing gas.}, archive = {J_ApJ}, author = {Zeyu Chen and Enci Wang and Hu Zou and Siwei Zou and Yang Gao and Huiyuan Wang and Haoran Yu and Cheng Jia and Haixin Li and Chengyu Ma and Yao Yao and Weiyu Ding and Runyu Zhu}, doi = {10.3847/1538-4357/ada942}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {81}, shortjournal = {The Astrophys. J.}, title = {The circumgalactic medium traced by mg ii absorption with DESI: Dependence on galaxy stellar mass, star formation rate, and azimuthal angle}, volume = {981}, year = {2025}, }
• (2025). Unveiling the interior structure and thermal evolution of super-earth GJ 486b. ApJ, 981(1), 80. (www)

  @article{ , abstract = {Recent ground- and space-based surveys have shown that planets between Earth and Neptune in size, known as "super-Earths," are among the most frequently found planets in the Galaxy. Although the JWST era has provided high-quality atmospheric data on many such super-Earths, modeling tools are crucial for understanding their unobservable interiors. Consequently, interior studies represent the next essential step in gaining a comprehensive understanding of this class of exoplanets. This study investigates the interior structure, thermal evolution, and atmospheric dynamics of the super-Earth GJ 486b using SERPINT , a 1D self-consistent coupled interior structure and evolution model, aiming to understand the planet's thermal evolution based on an Earth-like structure. Our results indicate that GJ 486b's core is approximately 1.34 times larger than Earth's, with a core pressure of about 1171 GPa. The thermal evolution model predicts that the planet's mantle cools and solidifies over approximately 0.93 Myr. As the magma ocean cools, water is released from the melt, forming a water-rich atmosphere during early solidification. Photolysis of water vapor and subsequent hydrogen escape lead to oxygen accumulation, forming a water- and oxygen-rich secondary atmosphere. Future high-sensitivity JWST observations, with improved wavelength coverage and the detection of additional trace gases, will enable a detailed analysis of the planet's atmospheric composition, providing crucial insights into the interior, surface, and subsurface properties of GJ 486b.}, archive = {J_ApJ}, author = {Chandan K. Sahu and Liton Majumdar and Sudipta Mridha and Harshit Krishna}, doi = {10.3847/1538-4357/adabbe}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {80}, shortjournal = {The Astrophys. J.}, title = {Unveiling the interior structure and thermal evolution of super-earth GJ 486b}, volume = {981}, year = {2025}, }
• (2025). One-dimensional linear analysis and numerical simulations of alfvén waves in a force-free magnetosphere around a kerr black hole. ApJ, 981(1), 79. (www)

  @article{ , abstract = {We perform 1D linear analysis and numerical simulations of the propagation of Alfvén waves in a force-free magnetosphere along magnetic field lines around a spinning black hole. We use the results to investigate the dynamic process of wave propagation and energy transport for Alfvén waves. As in a previous study using the Banados–Teitelboim–Zanelli spacetime, the Alfvén wave induces a fast magnetosonic wave in the case of a spinning black hole. Energy conservation is confirmed when this additional induced magnetosonic wave is considered. We also observe the reflection of the inwardly propagating Alfvén wave around the static limit, which is prohibited in theory when using the eikonal approximation.}, archive = {J_ApJ}, author = {Shinji Koide and Sousuke Noda and Masaaki Takahashi}, doi = {10.3847/1538-4357/adad67}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {79}, shortjournal = {The Astrophys. J.}, title = {One-dimensional linear analysis and numerical simulations of alfvén waves in a force-free magnetosphere around a kerr black hole}, volume = {981}, year = {2025}, }
• (2025). The formation histories of massive and quiescent galaxies in the 3 < z < 4.5 universe. ApJ, 981(1), 78. (www)

  @article{ , abstract = {We present the formation histories of 19 massive (≳3 × 10 10 M ⊙ ) quiescent (specific star formation rate, sSFR < 0.15 Gyr −1 ) galaxy candidates at z ~ 3.0–4.5 observed using JWST/NIRSpec. This completes the spectroscopic confirmation of the 24 K -selected quiescent galaxy sample from the ZFOURGE and 3DHST surveys. Utilizing Prism 1–5 μ m spectroscopy, we confirm that all 12 sources that eluded confirmation by ground-based spectroscopy lie at z > 3, resulting in a spectroscopically confirmed number density of ~1.4 × 10 −5 Mpc −3 between z ~ 3 and 4. Rest-frame U − V versus V − J color selections show high effectiveness in identifying quiescent galaxies, with a purity of ~90%. Our analysis shows that parametric star formation histories (SFHs) from FAST++ and binned SFHs from Prospector on average yield consistent results, revealing diverse formation and quenching times. The oldest galaxy formed ~6 × 10 10 M ⊙ by z ~ 10 and has been quiescent for over 1 Gyr at z ~ 3.2. We detect two galaxies with ongoing star formation and six with active galactic nuclei (AGNs). We demonstrate that the choice of stellar population models, stellar libraries, and nebular or AGN contributions does not significantly affect the derived average SFHs of the galaxies. We demonstrate that extending spectral fitting beyond the rest-frame optical regime reduces the inferred average star formation rates (SFRs) in the earliest time bins of the SFH reconstruction. The assumed SFH prior influences the SFR at early times, where spectral diagnostic power is limited. Simulated z ~ 3 quiescent galaxies from IllustrisTNG, SHARK, and Magneticum broadly match the average SFHs of the observed sample but struggle to capture the full diversity, particularly at early stages. Our results emphasize the need for mechanisms that rapidly build stellar mass and quench star formation within the first billion years of the Universe.}, archive = {J_ApJ}, author = {Themiya Nanayakkara and Karl Glazebrook and Corentin Schreiber and Harry Chittenden and Gabriel Brammer and James Esdaile and Colin Jacobs and Glenn G. Kacprzak and Lalitwadee Kawinwanichakij and Lucas C. Kimmig and Ivo Labbe and Claudia Lagos and Danilo Marchesini and M. Martìnez-Marìn and Z. Cemile Marsan and Pascal A. Oesch and Casey Papovich and Rhea-Silvia Remus and Kim-Vy H. Tran}, doi = {10.3847/1538-4357/ada6ac}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {78}, shortjournal = {The Astrophys. J.}, title = {The formation histories of massive and quiescent galaxies in the 3 < z < 4.5 universe}, volume = {981}, year = {2025}, }
• (2025). Empirical constraints on tidal dissipation in exoplanet host stars. ApJ, 981(1), 77. (www)

  @article{ , abstract = {The orbits of short-period exoplanets are sculpted by tidal dissipation. However, the mechanisms and associated efficiencies of these tidal interactions are poorly constrained. We present robust constraints on the tidal quality factors of short-period exoplanetary host stars through the usage of a novel empirical technique. The method is based on analyzing structures in the population-level distribution of tidal decay times, defined as the time remaining before a planet spirals into its host star due to stellar tides. Using simple synthetic planet population simulations and analytic theory, we show that there exists a steady-state portion of the decay time distribution with an approximately power-law form. This steady-state feature is clearly evident in the decay time distribution of the observed short-period planet population. We use this to constrain both the magnitude and frequency dependence of the stellar tidal quality factor and show that it must decrease sharply with planetary orbital period. Specifically, with Q^{\prime} ={Q}_{0}{(P/2\,\mathrm{days})}^{\alpha } , we find 10 5.5 ≲ Q 0 ≲ 10 7 and −4.33 ≲ α ≲ −2. Our results are most consistent with predictions from tidal resonance locking, in which the planets are locked into resonance with a tidally excited gravity mode in their host stars.}, archive = {J_ApJ}, author = {Sarah C. Millholland and Morgan MacLeod and Felicia Xiao}, doi = {10.3847/1538-4357/ada76d}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {77}, shortjournal = {The Astrophys. J.}, title = {Empirical constraints on tidal dissipation in exoplanet host stars}, volume = {981}, year = {2025}, }
• (2025). Simulating the arrival of multiple coronal mass ejections that triggered the gannon superstorm on 2024 may 10. ApJ, 981(1), 76. (www)

  @article{ , abstract = {The 2024 May 10 space weather event stands out as the most powerful storm recorded during the current solar cycle. This study employs a numerical framework utilizing a semiempirical coronal model, along with heliospheric upwind extrapolation with time dependence and cone coronal mass ejection (CME) models for the inner heliosphere, to forecast solar wind velocity and the arrival of CMEs associated with this event. The simulations were also carried out using the Space Weather Adaptive Simulation framework and a drag-based model (DBM) for this complex event of multiple CMEs. Predicted arrival times and velocities from these models are compared with actual observations at the Sun–Earth L1 point. These simulations reveal that three CMEs reached Earth nearly simultaneously, resulting in the extreme space weather event, followed by the arrival of a few more eruptions. The simulations accurately predicted arrival times with a discrepancy of approximately 5 hr or less for these CMEs. Further, the ensemble study of the DBM shows the sensitivity of the CME arrival time to the background solar wind speed and drag parameters. All three models have done fairly well in reproducing the arrival time closely to the actual observation of the CMEs responsible for the extreme geomagnetic storm of 2024 May 10. These rare solar storms offered a unique opportunity to thoroughly evaluate and validate our advanced models for predicting their arrival at Earth.}, archive = {J_ApJ}, author = {Smitha V. Thampi and Ankush Bhaskar and Prateek Mayank and Bhargav Vaidya and Indu Venugopal}, doi = {10.3847/1538-4357/ada93c}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {76}, shortjournal = {The Astrophys. J.}, title = {Simulating the arrival of multiple coronal mass ejections that triggered the gannon superstorm on 2024 may 10}, volume = {981}, year = {2025}, }
• (2025). Dynamic photometric variability in three young brown dwarfs in taurus: Detection of optical flares with TESS data. ApJ, 981(1), 75. (www)

  @article{ , abstract = {We present I -band time-series photometric variability studies of three known nearby (∼140 pc) and young (∼1 Myr) brown dwarfs (BD) in the Taurus star-forming region in the Perseus molecular cloud. From 10 nights of observations over a time span of 10 yr, with a typical run of 3–6 hr each night, we estimated that the BDs show unstable short-scale periodicity from 1.5 to 4.8 hr. Using the long-term photometry from the Transiting Exoplanet Survey Satellite (TESS), we have conducted a time-resolved variability analysis of CFHT-BD-Tau 3 and CFHT-BD-Tau 4, revealing orbital periods of ∼0.96 days and ∼3 days respectively, consistent with earlier studies. We also found two superflares in TESS sector 43 data for CFHT-BD-Tau 4 and estimated the flare energies as 7.09 × 10 35 erg and 3.75 × 10 36 erg. A magnetic field of ∼3.39 kG is required to generate such flare energies on this BD. We performed spot modeling analysis on CFHT-BD-Tau 3 and CFHT-BD-Tau 4 to address the variability detected in the data using the package BASSMAN. Spectral energy distribution and infrared colors of the sources suggest that they have a sufficient amount of circumstellar material around them.}, archive = {J_ApJ}, author = {Samrat Ghosh and Soumen Mondal and Somnath Dutta and Rajib Kumbhakar and Ramkrishna Das and Santosh Joshi and Sneh Lata}, doi = {10.3847/1538-4357/ada955}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {75}, shortjournal = {The Astrophys. J.}, title = {Dynamic photometric variability in three young brown dwarfs in taurus: Detection of optical flares with TESS data}, volume = {981}, year = {2025}, }
• (2025). A long-term study of mrk 50: Appearance and disappearance of soft excess. ApJ, 981(1), 74. (www)

  @article{ , abstract = {We present an extensive temporal and spectral study of the Seyfert 1 AGN Mrk 50 using 15 yr (2007–2022) of multiwavelength observations from XMM-Newton, Swift, and NuSTAR for the first time. From the timing analysis, we found that the source exhibited variability of ∼20% during the 2007 observation, which reduced to below 10% in the subsequent observations and became nonvariable in the observations from 2010 onward. From the spectral study, we found that the spectra are nearly featureless. Nondetection of absorption in the low-energy domain during the 15 yr of observation infers the absence of obscuration around the central engine, rendering the nucleus a "bare" type. A prominent soft X-ray excess below 2 keV was detected in the source spectrum during the observations between 2007 and 2010, which vanished during the later observations. To describe the nature of the soft excess, we use two physical models, such as warm Comptonization and blurred reflection from the ionized accretion disk. Both of the physical models explain the nature and origin of the soft excess in this source. Our analysis found that Mrk 50 accretes at a sub-Eddington accretion rate ( λ Edd = 0.13–0.02) during all of the observations used in this work.}, archive = {J_ApJ}, author = {Narendranath Layek and Prantik Nandi and Sachindra Naik and Arghajit Jana}, doi = {10.3847/1538-4357/adabc0}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {74}, shortjournal = {The Astrophys. J.}, title = {A long-term study of mrk 50: Appearance and disappearance of soft excess}, volume = {981}, year = {2025}, }
• (2025). Theoretical calculations on the effect of adsorbed atom coverage on the sodium exospheres of airless bodies. ApJ, 981(1), 73. (www)

  @article{ , abstract = {Our ability to understand the formation of the exospheres of airless bodies such as the Moon and Mercury has been hindered by uncertainties in how surface processes influence exospheric sources. Ejection processes important for exosphere formation rely on the notion that an emitted atom must first overcome an attractive energy with the surface to be ejected into the exosphere (the surface binding energy, SBE). Recent studies have shown that atoms from minerals are more tightly bound than commonly assumed, making it difficult to reconcile how such high volatile concentrations are being observed in the exospheres of airless bodies. Here, we used molecular dynamics modeling to explain the physics underlying the interaction of low-energy returning atoms, initially ejected below the escape energy of the body, with mineral surfaces. Global exosphere models make ill-informed assumptions for these interactions due to a lack of SBEs for adsorbed atoms. Results provide first-of-their-kind SBE distributions for adsorbed atoms and can be used by global models to better understand exosphere formation on airless bodies. We highlight the importance of adsorbate coverage and the atomic arrangement of a surface on the SBE. At low absorbate coverage sodium forms ionic bonds with oxygen, leading to tightly bound adsorbates (SBE ∼6 eV). At 1 ML of coverage the free O is terminated and Na is unable to form strong ionic bonds, leading to loosely bound adsorbates (SBE 1–3 eV). Emission processes from covered surfaces will be far more efficient than those without adsorbates. These improvements will allow for better interpretation of mission data such as from MESSENGER, BepiColombo, LADEE, Europa Clipper, and Artemis.}, archive = {J_ApJ}, author = {Liam S. Morrissey and Jesse Lewis and Amanda Ricketts and Deborah Berhanu and Caixia Bu and Chuanfei Dong and Denton S. Ebel and George E. Harlow and Ziyu Huang and Francois Leblanc and Menelaos Sarantos and Sebastien Verkercke}, doi = {10.3847/1538-4357/adad63}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {73}, shortjournal = {The Astrophys. J.}, title = {Theoretical calculations on the effect of adsorbed atom coverage on the sodium exospheres of airless bodies}, volume = {981}, year = {2025}, }
• (2025). Supersensitive seismic magnetometry of white dwarfs. ApJ, 981(1), 72. (www)

  @article{ , abstract = {The origin of the magnetic fields in white dwarfs (WDs) remains mysterious. Magnetic WDs are traditionally associated with field strengths ≳1 MG, set by the sensitivity of typical spectroscopic magnetic field measurements. Informed by recent developments in red giant magnetoasteroseismology, we revisit the use of WD pulsations as a seismic magnetometer. WD pulsations primarily probe near-surface magnetic fields, whose effect on oscillation mode frequencies is to asymmetrize rotational multiplets and, if strong enough, suppress gravity-mode propagation altogether. The sensitivity of seismology to magnetic fields increases strongly with mode period and decreases quickly with the depth of the partial ionization-driven surface convective zone. We place upper limits for the magnetic fields in 24 pulsating WDs: 20 hydrogen-atmosphere (DAV) and three helium-atmosphere (DBV) carbon–oxygen WDs, and one extremely low-mass (helium-core) pulsator. These bounds are typically ∼1–10 kG, although they can reach down to ∼10–100 G for DAVs and helium-core WDs in which lower-frequency modes are excited. Seismic magnetometry may enable new insights into the formation and evolution of WD magnetism.}, archive = {J_ApJ}, author = {Nicholas Z. Rui and Jim Fuller and J. J. Hermes}, doi = {10.3847/1538-4357/adaf9e}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {72}, shortjournal = {The Astrophys. J.}, title = {Supersensitive seismic magnetometry of white dwarfs}, volume = {981}, year = {2025}, }
• (2025). The assembly of supermassive black holes at z < 1 in early-type galaxies from scaling relations. ApJ, 981(1), 71. (www)

  @article{ , abstract = {The assembly of supermassive black hole (SMBH) mass ( M • ) and stellar mass ( M * ) in galaxies can be studied via the redshift evolution of the M • – M * relation, but the ways in which selection bias and physical assembly channels affect this evolution are uncertain. To address this, we compare the M • – M * relation for local massive ( M * > 10 10.5 M ⊙ ) quiescent early-type galaxies (ETGs) to that for massive ETGs hosting active galactic nuclei (AGN) at z ∼ 0.8. The restrictions on stellar mass and galaxy type limit the assembly channels that may connect the two relations. For the local sample we find \mathrm{log}({M}_{\bullet })=8.80+1.10(\mathrm{log}{M}_{* }-11) , in line with prior work. For the z ∼ 0.8 sample we find a bias-corrected relation: \mathrm{log}({M}_{\bullet })=7.80+1.25(\mathrm{log}{M}_{* }-11) . We show, however, that this relation depends on the stellar and SMBH mass functions used to compute the selection bias, the virial relation, the virial factor, and the active fraction, which together introduce uncertainty of up to ​​​​​​∼0.6 dex in the z ∼ 0.8 relation. Adopting reasonable choices of these parameters then our z ∼ 0.8 relation lies above that for z ∼ 0 AGN by ∼0.5 dex, but below our z ∼ 0 ETG relation by 0.4–1 dex in SMBH mass. We discuss possible sources of this offset, including further bias corrections, "downsizing" in SMBH mass assembly, and preferential SMBH growth. Our results highlight the need to reduce uncertainties from selection and measurement bias in SMBH and stellar masses at all redshifts.}, archive = {J_ApJ}, author = {D. Farrah and A. Engholm and E. Hatziminaoglou and S. Petty and F. Shankar and A. Efstathiou and K. Ejercito and K. Jones and M. Lacy and C. Lonsdale and C. Pearson and G. Tarlé and R. A. Windhorst and J. Afonso and D. L. Clements and K. S. Croker and L. K. Pitchford}, doi = {10.3847/1538-4357/adb0c7}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {71}, shortjournal = {The Astrophys. J.}, title = {The assembly of supermassive black holes at z < 1 in early-type galaxies from scaling relations}, volume = {981}, year = {2025}, }
• (2025). MAMMOTH-subaru. IV. large scale structure and clustering analysis of lyα emitters and lyα blobs at z = 2.2–2.3. ApJ, 981(1), 70. (www)

  @article{ , abstract = {We report the large scale structure and clustering analysis of Ly α emitters (LAEs) and Ly α blobs (LABs) at z = 2.2–2.3. Using 3341 LAEs, 117 LABs, and 58 bright (Ly α luminosity L Ly α > 10 43.4 erg s −1 ) LABs at z = 2.2–2.3 selected with Subaru/Hyper Suprime-Cam, we calculate the LAE overdensity to investigate the large scale structure at z = 2. We show that 79% of LABs and 83% of bright LABs are located in overdense regions, which is consistent with the trend found by previous studies that LABs are generally located in overdense regions. We find that one of our eight fields, dubbed J1349, contains 39/117 ≈ 33% of our LABs and 22/58 ≈ 38% of our bright LABs. A unique and overdense 2{4}^{{\prime} }\times 1{2}^{{\prime} } (40 × 20 comoving Mpc 2 ) region (J1347 protocluster) has 12 LABs (eight bright LABs). By comparing to SSA22, which is one of the most overdense LAB regions found by previous studies, we show that the J1347 protocluster region has a higher bright LAB density than the SSA22 protocluster region with a 1 σ significance. We calculate the angular correlation functions (ACFs) of LAEs and LABs in the unique J1349 field and fit the ACFs with a power-law function to measure the slopes. The bright LABs show a 5 σ larger slope, suggesting that bright LABs are more clustered than faint LAEs. Our LABs have a large galaxy bias of ∼5–7, which suggests that LABs generally reside in more massive dark matter halos (halo masses M ≳ 10 13 M ⊙ ) than faint LAEs.}, archive = {J_ApJ}, author = {Haibin Zhang and Zheng Cai and Mingyu Li and Yongming Liang and Nobunari Kashikawa and Ke Ma and Yunjing Wu and Qiong Li and Sean D. Johnson and Satoshi Kikuta and Masami Ouchi and Xiaohui Fan and Yuanhang Ning}, doi = {10.3847/1538-4357/adb41b}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {70}, shortjournal = {The Astrophys. J.}, title = {MAMMOTH-subaru. IV. large scale structure and clustering analysis of lyα emitters and lyα blobs at z = 2.2–2.3}, volume = {981}, year = {2025}, }
• (2025). Pseudo-newtonian simulation of a thin accretion disk around a Reissner–Nordström naked singularity. ApJ, 981(1), 69. (www)

  @article{ , abstract = {We present the first numerical simulations of a thin accretion disk around a Reissner–Nordström (RN) naked singularity (NkS; a charged point mass). The gravity of the RN NkS is modeled with a pseudo-Newtonian potential that reproduces exactly the radial dependence of the RN Keplerian orbital frequency; in particular, orbital angular velocity vanishes at the zero gravity radius and has a maximum at 4/3 of that radius. Angular momentum is transported outward by viscous stresses only outside the location of this maximum. Nonetheless, even at that radius, accretion proceeds at higher latitudes, the disk having thickened there owing to excess pressure. The accretion stops at a certain distance away from the singularity, with the material accumulating in a toroidal structure close to the zero-gravity sphere. The shape of the structure obtained in our simulations is reminiscent of fluid figures of equilibrium analytically derived in full general relativity for the RN singularity. The presence of a rotating ring, such as the one found in our simulations, could be an observational signature of an NkS. For charge-to-mass ratios close to but larger than unity, the inner edge of the quasi-toroidal inner accretion structure would be located well within the Schwarzschild marginally stable orbit (ISCO), and the maximum orbital frequency in thin accretion disks would be much higher than the Schwarzschild ISCO frequency.}, archive = {J_ApJ}, author = {Miljenko Čemeljić and Włodek Kluźniak and Ruchi Mishra and Maciek Wielgus}, doi = {10.3847/1538-4357/adb421}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {69}, shortjournal = {The Astrophys. J.}, title = {Pseudo-newtonian simulation of a thin accretion disk around a Reissner–Nordström naked singularity}, volume = {981}, year = {2025}, }
• (2025). The radiowave hunt for young stellar object emission and demographics (RADIOHEAD): A radio Luminosity–Spectral type dependence in Taurus–Auriga YSOs. ApJ, 981(1), 68. (www)

  @article{ , abstract = {We measure the radio continuum fluxes at the locations of all Gaia-confirmed members of Taurus–Auriga using Karl G. Jansky Very Large Array Sky Survey data (VLASS; 2–4 GHz, σ VLASS ~ 110–140 μ Jy, 2 \mathop{.}\limits^{\unicode{x02033}} 5 resolution) spanning three VLASS epochs (2019, 2021, and 2023). We present 35 detections coincident with young Taurus–Auriga stars (29 in individual VLASS images, 6 via stacking). We find a strong dependence on spectral type, wherein the fractional detection rate of radio emission coincident with early-type young stellar objects (YSOs) is systematically higher than late-type YSOs, ranging from 25% ± 13% for B–F YSOs, 21% ± 11% for G YSOs, 18.4% ± 6.3% for K0–K4 YSOs, 15.5% ± 5.4% for K5–K9 YSOs, 7.0% ± 2.7% for M0–M2 YSOs, 2.3% ± 0.9% for M3–M6 YSOs, and 1.9% ± 1.9% for YSOs with SpTs later than M7. We present cumulative density distributions of radio luminosity densities that demonstrate a significant luminosity enhancement for early- versus late-type YSOs. We find 25% of the detected sources to be significantly variable. We discuss possible interpretations of this dependence, which may reflect stellar magnetic activity, binary interactions, or stellar flaring. We find that the mid-infrared YSO class is a strong indicator of radio detectability consistent with higher frequency Taurus–Auriga VLA surveys, with class III stars detected at a rate of 8.8% ± 1.6%, class IIs at 2.0% ± 1.2%, and combined class 0s, Is and Fs at 8.0% ± 5.4%.}, archive = {J_ApJ}, author = {Ramisa Akther Rahman and Joshua Bennett Lovell and Eric W. Koch and David J. Wilner and Sean M. Andrews and Kristina Monsch and Dan Ha}, doi = {10.3847/1538-4357/ad9f37}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {68}, shortjournal = {The Astrophys. J.}, title = {The radiowave hunt for young stellar object emission and demographics (RADIOHEAD): A radio Luminosity–Spectral type dependence in Taurus–Auriga YSOs}, volume = {981}, year = {2025}, }
• (2025). TelescopeML. II. convolutional neural networks for predicting brown dwarf atmospheric parameters. ApJ, 981(1), 67. (www)

  @article{ , abstract = {Accurately and swiftly predicting the parameters of brown dwarf atmospheres from observational spectra is crucial for understanding their atmospheric composition and guiding future follow-up observations. Here, we utilized convolutional neural networks (CNNs) as a high-performance deep learning algorithm, training them with synthetic spectra generated from Sonora–Bobcat cloudless and equilibrium model grids to infer effective temperatures ( T eff ), surface gravities ( \mathrm{log}\,g ), carbon-to-oxygen ratios (C/O), and metallicities ([M/H]). The performance metric, or R 2 value (the coefficient of determination), of the trained CNNs in predicting T eff , \mathrm{log}\,g , C/O, and [M/H] is 1.0, 1.0, 0.99, and 0.93 on both the training and test sets, respectively. We apply our trained CNN model on the three well-known T dwarf benchmarks, HD 3651B, GJ 570D, and Ross 458C. For HD 3651B and GJ 570D, we find that our predicted T eff and \mathrm{log}\,g are in good agreement with some of the previous modeling studies from forward and retrieval approaches, but the [M/H] is underestimated up to ≈0.3 dex. For Ross 458C, our CNN model predicts the \mathrm{log}\,g accurately but tends to overestimate T eff by ≈150 K and [M/H] by ≈1.0 dex compared to the previous modelings, which likely happens because our model grids lack disequilibrium chemistry and clouds. We also find that the C/O ratio tends to be higher than solar if not kept fixed. Concurrently, all modules and functions used to train, develop, and deploy the CNNs and process the spectra are consolidated into a Python PyPI package named TelescopeML , which is publicly available along with a thoroughly documented tutorial covering installation, deployment, and core concepts.}, archive = {J_ApJ}, author = {Ehsan (Sam) Gharib-Nezhad and Hamed Valizadegan and Natasha E. Batalha and Miguel J. S. Martinho and Ben W.P. Lew}, doi = {10.3847/1538-4357/ada1d2}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {67}, shortjournal = {The Astrophys. J.}, title = {TelescopeML. II. convolutional neural networks for predicting brown dwarf atmospheric parameters}, volume = {981}, year = {2025}, }
• (2025). Recovering injected astrophysics from the LISA double white dwarf binaries. ApJ, 981(1), 66. (www)

  @article{ , abstract = {We present the successful recovery of common-envelope ejection efficiency assumed in a simulated population of double white dwarf (DWD) binaries like those which may be observed by the future Laser Interferometer Space Antenna (LISA) mission. We simulate the formation of DWD binaries by using the COSMIC population synthesis code to sample binary formation conditions such as initial mass function, metallicity of star formation, initial orbital period, and initial eccentricity. These binaries are placed in the m12i synthetic Milky Way–like galaxy, and their signal-to-noise ratio (SNR) for the LISA instrument is estimated, considering a Galactic gravitational-wave foreground informed by the population. Through the use of Fisher estimates, we construct a likelihood function for the measurement error of the LISA-bright DWD binaries (≥20 SNR, f GW ≥ 5 mHz), in their gravitational-wave frequency ( f GW ) and chirp mass. By repeating this process for different assumptions of the common-envelope ejection efficiency, we apply Bayesian hierarchical inference to find the best match to an injected astrophysical assumption for a fiducial population model. We conclude that the impact of common-envelope ejection efficiency on the mass-transfer processes involved in DWD formation may be statistically relevant in the future observed LISA population, and that constraints on binary formation may be found by comparing simulated populations to a future observed population.}, archive = {J_ApJ}, author = {Vera Delfavero and Katelyn Breivik and Sarah Thiele and Richard O’Shaughnessy and John G. Baker}, doi = {10.3847/1538-4357/ada9e2}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {66}, shortjournal = {The Astrophys. J.}, title = {Recovering injected astrophysics from the LISA double white dwarf binaries}, volume = {981}, year = {2025}, }
• (2025). Sporadic E-like topside layer driven by wind shear in the martian ionosphere. ApJ, 981(1), 65. (www)

  @article{ , abstract = {Ionospheric plasma density disturbances significantly affect radio wave propagation, impacting communication and planetary exploration. At Earth, sporadic E layers (Es) are commonly observed. They are characterized by thin, high-density plasma structures in the E-region ionosphere, primarily formed by electromagnetic forces induced by horizontal wind shears. Similar sharp vertical electron density changes have also been observed in the topside of the Martian ionosphere by missions like Mars Global Surveyor, Mars Express, and Mars Atmosphere and Volatile EvolutioN. Recent studies suggest that such structures observed on Mars can be attributed to a sporadic E-like mechanism induced by magnetic shear, which can be referred to as Es-like structures. While wind shear theoretically contributes to such events, no observational evidence currently reports wind shear as an explanation for these density gradients on Mars. In this study, we report a novel observation of an Es-like topside layer in the Martian ionosphere, characterized by both density layer and rift (an abrupt depletion in density), where wind and magnetic shear are simultaneously observed. Statistical analysis of 305 orbits with wind speed observations revealed wind shear is observed in nine Es-like events, primarily occurring in strong crustal magnetic field regions. Simulations suggest that the observed rift and layer can be explained either by "wind shear" or by "wind and magnetic shear" under strong crustal magnetic field. This study provides new observations of Es-like events on Mars and serves as a credible candidate for the contribution of wind shear to the formation of an Es-like topside layer.}, archive = {J_ApJ}, author = {Rong Tian and Chunhua Jiang and Christopher Michael Fowler and Beatriz Sánchez-Cano and Glyn Collinson and David J. Andrews and Wenjie Yin and Guobin Yang and Tongxin Liu and Chongzhe Lao and Yaogai Hu}, doi = {10.3847/1538-4357/adaaeb}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {65}, shortjournal = {The Astrophys. J.}, title = {Sporadic E-like topside layer driven by wind shear in the martian ionosphere}, volume = {981}, year = {2025}, }
• (2025). Rotational spectrum and search for lactonitrile toward sgr B2(N). ApJ, 981(1), 64. (www)

  @article{ , abstract = {Laboratory experiments on interstellar ice analogs have demonstrated that ice mixtures containing acetaldehyde (CH 3 CHO) and hydrogen cyanide (HCN) in the presence of ammonia (NH 3 ), water (H 2 O), or an NH 3 /H 2 O mixture allow the formation of the chiral molecule lactonitrile (2-hydroxypropionitrile; CH 3 CH(OH)CN). These findings place lactonitrile among possible interstellar molecules, especially when its methyl-shortened derivative glycolonitrile and the precursors are known interstellar species. To support the search for lactonitrile in interstellar space, we present measurements under supersonic expansion conditions in the 6–16 GHz frequency range, along with a detailed analysis of its room-temperature rotational spectrum from 75 to 325 GHz. Improved and extended sets of molecular parameters, determined from the newly measured data and selected literature measurements, are obtained for two conformers of lactonitrile, with accuracies conducive to reliable interstellar searches. We report the nondetection of lactonitrile toward the main hot core Sgr B2(N1S), with a column density upper limit 1 order of magnitude higher than the upper limit derived for the related molecule glycolonitrile.}, archive = {J_ApJ}, author = {A. Insausti and E. R. Alonso and L. Kolesniková and A. Belloche and I. León and S. Mato}, doi = {10.3847/1538-4357/adad54}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {64}, shortjournal = {The Astrophys. J.}, title = {Rotational spectrum and search for lactonitrile toward sgr B2(N)}, volume = {981}, year = {2025}, }
• (2025). Quantifying advantages of a moving mesh in nuclear hydrodynamics. ApJ, 981(1), 63. (www)

  @article{ , abstract = {Many astrophysical explosions, such as type Ia supernovae, classical novae, and X-ray bursts, are dominated by thermonuclear runaway. To model these processes accurately, one must evolve nuclear reactions concurrently with hydrodynamics. We present an application of the moving mesh technique to this field of computation with the aim of explicitly testing the advantages of the method against the fixed mesh case. By way of traditional Strang splitting, our work couples a 13 isotope nuclear reaction network to a 1D moving mesh, Cartesian geometry hydrodynamics code. We explore three reacting problems: an acoustic pulse, a burning shock, and an advecting deflagration. Additionally, using the shock jump conditions, we semianalytically solve the burning shock problem under the assumption of quick, complete burning with the hope of establishing a useful and easy-to-set-up test problem. Strong moving mesh advantages are found in advecting, deflagrating flame fronts, where the technique dramatically reduces numerical diffusion that would otherwise lead to very fast artificial deflagration.}, archive = {J_ApJ}, author = {Dillon L. Hasenour and Paul C. Duffell}, doi = {10.3847/1538-4357/adaeb0}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {63}, shortjournal = {The Astrophys. J.}, title = {Quantifying advantages of a moving mesh in nuclear hydrodynamics}, volume = {981}, year = {2025}, }
• (2025). Primordial black hole mergers as probes of dark matter in the galactic center. ApJ, 981(1), 62. (www)

  @article{ , abstract = {Primordial black holes (PBHs) from the early Universe that can contribute to dark matter (DM) abundance have been linked to gravitational-wave observations. Supermassive black holes at the centers of galaxies are expected to modify the distribution of DM in their vicinity and can result in highly concentrated DM spikes. We revisit PBH merger rates in the presence of DM spikes, tracking their history. We find novel peaked structure in the redshift evolution of PBH merger rates at low redshifts around z ∼ 5. These effects are generic and are present for distinct PBH mass functions and spike profiles, and also can be linked to peaked structure in the redshift evolution of the star formation rate. Redshift evolution characteristics of PBH merger rates can be distinguished from astrophysical black hole contributions and observable with gravitational waves, enabling them to serve as probes of DM in galactic centers.}, archive = {J_ApJ}, author = {Qianhang Ding and Minxi He and Volodymyr Takhistov}, doi = {10.3847/1538-4357/adaeb4}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {62}, shortjournal = {The Astrophys. J.}, title = {Primordial black hole mergers as probes of dark matter in the galactic center}, volume = {981}, year = {2025}, }
• (2025). Predicting high-magnification events in microlensed quasars in the era of LSST using recurrent neural networks. ApJ, 981(1), 61. (www)

  @article{ , abstract = {Upcoming wide-field surveys, such as the Rubin Observatory's Legacy Survey of Space and Time (LSST), will monitor thousands of strongly lensed quasars over a 10 yr period. Many of these monitored quasars will undergo high-magnification events (HMEs) through microlensing, as the accretion disk crosses a caustic—places of infinite magnification. Microlensing allows us to map the inner regions of the accretion disk as it crosses a caustic, even at large cosmological distances. The observational cadences of LSST are not ideal for probing the inner regions of the accretion disk, so there is a need to predict HMEs as early as possible, to trigger high-cadence multiband or spectroscopic follow-up observations. Here, we simulate a diverse and realistic sample of 10 yr quasar microlensing light curves to train a recurrent neural network to predict HMEs before they occur, by classifying the locations of the peaks at each time step. This is the first deep-learning approach for predicting HMEs. We give estimates of how well we expect to predict HME peaks during LSST and benchmark how our metrics change with different cadence strategies. With LSST-like observations, we can predict approximately 55% of HME peaks, corresponding to tens to hundreds per year and a false-positive rate of around 20% compared to the total number of HMEs. Our network can be continuously applied throughout the LSST survey, providing crucial alerts for optimizing follow-up resources.}, archive = {J_ApJ}, author = {Joshua Fagin and Eric Paic and Favio Neira and Henry Best and Timo Anguita and Martin Millon and Matthew O’Dowd and Dominique Sluse and Georgios Vernardos}, doi = {10.3847/1538-4357/adaebb}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {61}, shortjournal = {The Astrophys. J.}, title = {Predicting high-magnification events in microlensed quasars in the era of LSST using recurrent neural networks}, volume = {981}, year = {2025}, }
• (2025). SQuIGG$\overrightarrow{L}$E: Observational evidence of low ongoing star formation rates in gas-rich post-starburst galaxies. ApJ, 981(1), 60. (www)

  @article{ , abstract = {Atacama Large Millimeter/submillimeter Array observations have shown that candidate "post-starburst" galaxies (PSBs) at z ∼ 0.6 can retain significant molecular gas reservoirs. These results would imply that—unlike many model predictions—galaxies can shut down their star formation before their cold gas reservoirs are depleted. However, these studies inferred star formation rates (SFRs) either from [O ii ] line fluxes or from spectral energy distribution (SED) modeling and could have missed large dust-obscured contributions to the SFRs. In this study, we present Keck/NIRES observations of 13 massive ( M * ≳ 10 11 M ⊙ ) PSBs, which allow us to estimate H α SFRs in these gas-rich PSBs. We confirm the previously inferred low SFRs for the majority of the sample: 11/13 targets show clear H α absorption, with minimal infilling indicating dust-corrected SFRs of <4.1 M ⊙ yr −1 . These SFRs are notably low given the large H 2 reservoirs (∼(1–5) × 10 10 M ⊙ ) present in 5/13 of these galaxies, placing them significantly offset from star-forming galaxies on the Kennicutt–Schmidt relation for star-forming galaxies. The [N ii ]/H α ratios of all 13 PSBs imply contributions from non-star-forming ionization mechanisms (e.g., active galactic nuclei, shocks, or hot evolved stars) to their H α emission, suggesting that even these low ongoing SFRs may be overestimated. These low H α SFRs, dust corrected using A v estimates from SED fitting, confirm that these galaxies are very likely quiescent and, thus, that galaxies can quench before their cold gas reservoirs are fully depleted.}, archive = {J_ApJ}, author = {Pengpei Zhu and Katherine A. Suess and Mariska Kriek and David J. Setton and Rachel Bezanson and Vincenzo Donofrio and Robert Feldmann and Andy D. Goulding and Jenny E. Greene and Desika Narayanan and Justin Spilker}, doi = {10.3847/1538-4357/adaf1c}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {60}, shortjournal = {The Astrophys. J.}, title = {SQuIGG$\overrightarrow{L}$E: Observational evidence of low ongoing star formation rates in gas-rich post-starburst galaxies}, volume = {981}, year = {2025}, }
• (2025). The polarization signatures of the inverse cascade in magnetic turbulence. ApJ, 981(1), 59. (www)

  @article{ , abstract = {The inverse cascade of magnetic energy from smaller to larger scales is a key physical process for the formation of coherent magnetic fields in many astronomical turbulent systems. Synchrotron radiation polarization, an observable measurement closely related to the magnetic field topology and particle distribution function, is an important and promising tool for diagnosing this highly dynamic process. Here, for the first time, we use the first-principle particle-in-cell simulations to systematically investigate the polarization signatures during the inverse cascade of the magnetic field. We find that the polarization degree (PD) increases rapidly with the increase in the coherent scale of the magnetic field during the inverse transfer and its growth rate is positively correlated with the rate of inverse transfer and could be described by a logarithmic growth formula, and we also identify that the scale with the largest PD variation is coincident with this coherent scale by applying the spatial filter method. In addition, we show that the polarization signature is significantly dependent on the radiated photon energy and the line of sight, with high-energy radiation more sensitive to the increase in the coherent scale of the turbulent magnetic field than low-energy radiation, and the polarization characteristics present significant pitch-angle anisotropy due to the acceleration of particles in the presence of a strong background magnetic field. Our results provide a promising method to explore the astrophysical inverse cascade process and infer the coherent scale of turbulence, which could be validated by astronomical observations in the future.}, archive = {J_ApJ}, author = {X. W. Zhu and Y. Xie and Z. Lei and W. Q. Yuan and X. X. Jin and Z. H. Zhao and B. Qiao}, doi = {10.3847/1538-4357/adaf96}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {59}, shortjournal = {The Astrophys. J.}, title = {The polarization signatures of the inverse cascade in magnetic turbulence}, volume = {981}, year = {2025}, }
• (2025). Probing three-dimensional magnetic fields. IV. synchrotron polarization derivative and vision transformer. ApJ, 981(1), 58. (www)

  @article{ , abstract = {Measuring the 3D spatial distribution of magnetic fields in the interstellar medium and the intracluster medium is crucial yet challenging. The probing of the 3D magnetic field's 3D distribution, including the field plane-of-sky orientation ( ψ ), the magnetic field's inclination angle ( γ ) relative to the line of sight, and the magnetization (∼the inverse Alfvén Mach number {M}_{{\rm{A}}}^{-1} ), at different distances from the observer makes the task even more formidable. However, the anisotropy and Faraday decorrelation effect in polarized synchrotron emission offer a unique solution. We show that due to the Faraday decorrelation, only regions up to a certain effective path length along the line of sight contribute to the statistical correlation of the measured polarization. The 3D spatial information can be consequently derived from synchrotron polarization derivatives (SPDs), which are calculated from the difference in synchrotron polarization across two wavelengths. We find that the 3D magnetic field can be estimated from the anisotropy observed in SPDs: the elongation direction of the SPD structures probes ψ , and the degree of SPD anisotropy, along with its morphological curvature, provides insights into {M}_{{\rm{A}}}^{-1} and γ . To extract these anisotropic features and their correlation with the 3D magnetic field, we propose utilizing a machine learning approach, specifically the Vision Transformer (ViT) architecture, which was exemplified by the success of ChatGPT. We train the ViT using synthetic synchrotron observations generated from magnetohydrodynamic turbulence simulations in sub-Alfvénic and super-Alfvénic conditions. We show that ViT's application to multiwavelength SPDs can successfully reconstruct the 3D magnetic fields' 3D spatial distribution.}, archive = {J_ApJ}, author = {Yue Hu and Alex Lazarian}, doi = {10.3847/1538-4357/adaf97}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {58}, shortjournal = {The Astrophys. J.}, title = {Probing three-dimensional magnetic fields. IV. synchrotron polarization derivative and vision transformer}, volume = {981}, year = {2025}, }
• (2025). New perspective on the multiple-population phenomenon in galactic globular clusters from a wide-field photometric survey. ApJ, 981(1), 57. (www)

  @article{ , abstract = {Wide-field photometry of Galactic globular clusters (GCs) has been investigated to overcome limitations from the small field of view of the Hubble Space Telescope in the study of multiple populations. In particular, "chromosome maps" (ChMs) built with ground-based photometry were constructed to identify the first- and second-generation (1G and 2G) stars over the wide field of view. The ChMs allow us to derive the fraction of distinct populations in an analyzed field of view. We present here the radial distribution of the 2G fraction in 29 GCs. The distributions show that all the GCs have either a flat distribution or more centrally concentrated 2G stars. Notably, we find that the fraction of 1G stars outside the half-light radius is clearly bifurcated across all mass range. It implies that a group of GCs with lower 1G fractions (hereafter Group II) have efficiently lost their 1G stars in the outermost cluster regions. In fact, in connection with the trends of the radial distribution, most GCs of Group II have spatially mixed populations, while only less massive GCs in Group I (a group with higher 1G fraction) show that feature. Lastly, we investigate links between these two groups and host cluster parameters. We find that most GCs of Group II are distributed along a broader range of galactocentric distances with smaller perigalactic distances  <  3.5 kpc. Besides, by using the Gaia data, it is observed that Group II GCs have higher energy on the integrals of motion diagrams than Group I GCs.}, archive = {J_ApJ}, author = {S. Jang and A. P. Milone and A. F. Marino and M. Tailo and E. Dondoglio and M. V. Legnardi and G. Cordoni and T. Ziliotto and E. P. Lagioia and M. Carlos and A. Mohandasan and E. Bortolan and Y.-W. Lee}, doi = {10.3847/1538-4357/adafa1}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {57}, shortjournal = {The Astrophys. J.}, title = {New perspective on the multiple-population phenomenon in galactic globular clusters from a wide-field photometric survey}, volume = {981}, year = {2025}, }
• (2025). Green peas in the southern sky: Broadband color selection and spectroscopic follow-up. ApJ, 981(1), 56. (www)

  @article{ , abstract = {We present a systematic search for 1696 green pea (GP) galaxy candidates in the southern hemisphere selected from the Dark Energy Survey Data Release 2 and provide preliminary results from spectroscopic follow-up observations of 26 targets chosen among them. Our selection criteria include the colors in the gri bands and compact morphology in the color-composite images. The multiwavelength spectral energy distribution fitting shows that the selected GP candidates exhibit star formation rates up to several tens of M ⊙ yr −1 . With the mean stellar mass of \mathrm{log}\,{M}_{* }/{M}_{\odot }=8.6 , GP candidates are located at roughly 1 dex above the main sequence of star-forming galaxies at z ∼ 0.3. Spectroscopic follow-up observations of the GP candidates with Gemini/Gemini Multi-Object Spectrograph are underway. All 26 targets are spectroscopically confirmed to be at z = 0.3–0.41 and have an [O iii ] equivalent width larger than 85 Å, classified to be starbursts with low-to-moderate dust attenuation. These confirmed GPs show a lower metallicity offset from the mass–metallicity relation of local star-forming galaxies, indicating that GPs are less chemically evolved systems at their early stage of evolution.}, archive = {J_ApJ}, author = {Yejin Jeong and Hyunjin Shim and Eunchong Kim and Jeong Hwan Lee}, doi = {10.3847/1538-4357/adafa4}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {56}, shortjournal = {The Astrophys. J.}, title = {Green peas in the southern sky: Broadband color selection and spectroscopic follow-up}, volume = {981}, year = {2025}, }
• (2025). Origin of α-poor very metal-poor stars. ApJ, 981(1), 55. (www)

  @article{ , abstract = {Among very metal-poor (VMP) stars, α -poor VMP ( α -PVMP) stars that have subsolar values of [X/Fe] for Mg and other α elements are rare and are thought to have been formed from gas polluted by Type 1a supernova (SN 1a). However, recent analyses indicate that pure core-collapse supernova (CCSN) ejecta can also be a likely source. We perform a detailed analysis of 17 α -PVMP stars by considering six different scenarios relevant to the early Galaxy. We consider a single pair-instability supernova (PISN) and a single CCSN. Additionally, we consider the combination of ejecta from a CCSN with ejecta from another CCSN, a PISN, a near-Chandrasekhar mass (near- M Ch ) SN 1a, and a sub-Chandrasekhar mass (sub- M Ch ) SN 1a. A clear signature can only be established for sub- M Ch SN 1a with a near-smoking-gun signature in SDSS J0018-0939 and a reasonably clear signature in ET0381. The majority (82%) of α -PVMP stars can be explained by pure CCSN ejecta and do not require any SN 1a contribution. However, the combination of CCSN and sub- M Ch SN 1a ejecta can also explain most (76%) of α -PVMP stars. In contrast, the combination of ejecta from CCSN with near- M Ch SN 1a and PISN can fit 41% and 29% of the stars, respectively. The single PISN scenario is strongly ruled out for all stars. Our results indicate that α -PVMP stars are equally compatible with pure CCSN ejecta and a combination of CCSN and SN 1a ejecta, with sub- M Ch SN 1a being roughly twice as frequent as near- M Ch SN 1a.}, archive = {J_ApJ}, author = {S. K. Jeena and Projjwal Banerjee}, doi = {10.3847/1538-4357/adb0c5}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {55}, shortjournal = {The Astrophys. J.}, title = {Origin of α-poor very metal-poor stars}, volume = {981}, year = {2025}, }
• (2025). The white dwarf pareto: Tracing mass loss in binary systems. ApJ, 981(1), 54. (www)

  @article{ , abstract = {The white dwarf mass distribution has been studied primarily at two extremes: objects that presumably evolved as single stars, and members of close binaries that likely underwent substantial interaction. This work considers the intermediate separation regime of  ∼1 au and demonstrates how binary interaction affects white dwarf masses. The binary mass ratio distribution is utilized for this purpose. Modeled as a truncated Pareto profile, this distribution provides insights into the populations' properties and evolutionary history. When applied to homogeneous samples of binaries with giant primaries of similar age, the distribution's shape constrains the fraction of white dwarf companions, the white dwarf mass distribution, and the properties of their progenitors. As a test case, this method is applied to a small spectroscopic sample of binaries in open clusters with red giant primaries and orbital periods between 0.5 and 20 yr. The analysis reveals that white dwarfs in these systems are  ∼20% less massive than their isolated counterparts, with a typical mass of  ∼0.55 M ⊙ . Their progenitors likely lost 80%−85% of their mass, with binary interactions enhancing mass loss by an additional  ∼0.2 M ⊙ . These findings highlight the utility of this approach for studying binary evolution and improving population models, particularly with future data sets from Gaia and other large-scale surveys.}, archive = {J_ApJ}, author = {Sahar Shahaf}, doi = {10.3847/1538-4357/adb156}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {54}, shortjournal = {The Astrophys. J.}, title = {The white dwarf pareto: Tracing mass loss in binary systems}, volume = {981}, year = {2025}, }
• (2025). Magnetohydrodynamic simulation of a coronal mass ejection observed during the near-radial alignment of solar orbiter and earth. ApJ, 981(1), 53. (www)

  @article{ , abstract = {Interplanetary coronal mass ejections (ICMEs) are the primary sources of geomagnetic storms at Earth. The negative out-of-ecliptic component ( B z ) of magnetic field in the ICME or its associated sheath region is necessary for it to be geoeffective. For this reason, magnetohydrodynamic simulations of CMEs containing data-constrained flux ropes are more suitable for forecasting their geoeffectiveness as compared to hydrodynamic models of the CME. ICMEs observed in situ by radially aligned spacecraft can provide an important setup to validate the physics-based heliospheric modeling of CMEs. In this work, we use the constant-turn flux rope (CTFR) model to study an ICME that was observed in situ by Solar Orbiter (SolO) and at Earth, when they were in a near-radial alignment. This was a stealth CME that erupted on 2020 April 14 and reached Earth on 2020 April 20 with a weak shock and a smoothly rotating magnetic field signature. We found that the CTFR model was able to reproduce the rotating magnetic field signature at both SolO and Earth with very good accuracy. The simulated ICME arrived 5 hr late at SolO and 5 hr ahead at Earth, when compared to the observed ICME. We compare the propagation of the CME front through the inner heliosphere using synthetic J-maps and those observed in the heliospheric imager data and discuss the role of incorrect ambient solar wind background on kinematics of the simulated CME. This study supports the choice of the CTFR model for reproducing the magnetic field of ICMEs.}, archive = {J_ApJ}, author = {Talwinder Singh and Dinesha V. Hegde and Tae K. Kim and Nikolai V. Pogorelov}, doi = {10.3847/1538-4357/adb1ac}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {53}, shortjournal = {The Astrophys. J.}, title = {Magnetohydrodynamic simulation of a coronal mass ejection observed during the near-radial alignment of solar orbiter and earth}, volume = {981}, year = {2025}, }
• (2025). Weak-lensing mass reconstruction of galaxy clusters with a convolutional neural network. II. application to next-generation wide-field surveys. ApJ, 981(1), 52. (www)

  @article{ , abstract = {Traditional weak-lensing mass reconstruction techniques suffer from various artifacts, including noise amplification and the mass-sheet degeneracy. In S. E. Hong et al., we demonstrated that many of these pitfalls of traditional mass reconstruction can be mitigated using a deep learning approach based on a convolutional neural network (CNN). In this paper, we present our improvements and report on the detailed performance of our CNN algorithm applied to next-generation wide-field (WF) observations. Assuming the field of view ( 3\mathop{.}\limits^{\unicode{x000b0}}\,5\times 3\mathop{.}\limits^{\unicode{x000b0}}\,5 ) and depth (27 mag at 5 σ ) of the Vera C. Rubin Observatory, we generated training data sets of mock shear catalogs with a source density of 33 arcmin −2 from cosmological simulation ray-tracing data. We find that the current CNN method provides high-fidelity reconstructions consistent with the true convergence field, restoring both small- and large-scale structures. In addition, the cluster detection utilizing our CNN reconstruction achieves ∼75% completeness down to ∼10 14 M ⊙ . We anticipate that this CNN-based mass reconstruction will be a powerful tool in the Rubin era, enabling fast and robust WF mass reconstructions on a routine basis.}, archive = {J_ApJ}, author = {Sangjun Cha and M. James Jee and Sungwook E. Hong and Sangnam Park and Dongsu Bak and Taehwan Kim}, doi = {10.3847/1538-4357/adb1b7}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {52}, shortjournal = {The Astrophys. J.}, title = {Weak-lensing mass reconstruction of galaxy clusters with a convolutional neural network. II. application to next-generation wide-field surveys}, volume = {981}, year = {2025}, }
• (2025). Large molecular and dust reservoir of a gravitationally lensed submillimeter galaxy behind the lupus i molecular cloud. ApJ, 981(1), 51. (www)

  @article{ , abstract = {We report the Australian Telescope Compact Array and Nobeyama 45 m telescope detection of a remarkably bright ( S 1.1mm = 44 mJy) submillimeter galaxy MM J154506.4−344318 in emission lines at 48.5 and 97.0 GHz, respectively. We also identify part of an emission line at ≈218.3 GHz using the Atacama Large Millimeter/submillimeter Array (ALMA). Together with photometric redshift estimates and the ratio between the line and infrared luminosities, we conclude that the emission lines are most likely to be the J = 2–1, 4–3, and 9–8 transitions of 12 CO at redshift z = 3.753 ± 0.001. ALMA 1.3 mm continuum imaging reveals an arc and a spot separated by an angular distance of 1\mathop{.}\limits^{^{\prime\prime} }6 , indicative of a strongly lensed dusty star-forming galaxy with respective molecular and dust masses of \mathrm{log}{M}_{{\rm{mol}}}/{M}_{\odot }\approx 11.5 and \mathrm{log}{M}_{{\rm{dust}}}/{M}_{\odot }\approx 9.4 after being corrected for ≈6.6 × gravitational magnification. The inferred dust-to-gas mass ratio is found to be high (≈0.0083) among coeval dusty star-forming galaxies, implying the presence of a massive, chemically enriched reservoir of cool interstellar medium at z ≈ 4, or 1.6 Gyr after the Big Bang.}, archive = {J_ApJ}, author = {Yoichi Tamura and Akio Taniguchi and Tom J. L. C. Bakx and Itziar De Gregorio-Monsalvo and Masato Hagimoto and Soh Ikarashi and Ryohei Kawabe and Kotaro Kohno and Kouichiro Nakanishi and Tatsuya Takekoshi and Yoshito Shimajiri and Takashi Tsukagoshi and Bunyo Hatsukade and Daisuke Iono and Hideo Matsuhara and Kazuya Saigo and Masao Saito}, doi = {10.3847/1538-4357/adb1b9}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {51}, shortjournal = {The Astrophys. J.}, title = {Large molecular and dust reservoir of a gravitationally lensed submillimeter galaxy behind the lupus i molecular cloud}, volume = {981}, year = {2025}, }
• (2025). Fifteen years of m31* X-ray variability and flares. ApJ, 981(1), 50. (www)

  @article{ , abstract = {We append an additional 15 yr (2009–2024) to the Chandra X-ray light curve of M31*, the supermassive black hole (SMBH) at the center of M31, the Andromeda galaxy. Extending and expanding on the work in Z. Li et al., we show that M31* has remained in an elevated X-ray state from 2006 through at least 2016 (when regular Chandra monitoring ceased) and likely through 2024, with the most recent observations still showing an elevated X-ray flux. We identify one moderate flare in 2013 where the other nuclear X-ray sources are in low-flux states, making that flare a valuable target for follow-up with multiwavelength and multimessenger archival data. We extract a mostly uncontaminated spectrum for M31* from this observation, showing that its X-ray properties are similar to those observed at Sgr A* in its quiescent state by Baganoff et al. Furthermore, we find no substantial change in the source's hardness ratio in the 2006 and 2013 flares compared to the post-2006 elevated state, suggesting the these flares are increases in the regular X-ray emission mechanisms instead of entirely new emission modes. Our extended light curve for M31* provides valuable context for multimessenger or multiwavelength observations of nearby SMBHs.}, archive = {J_ApJ}, author = {Stephen DiKerby and Shuo Zhang and Jimmy Irwin}, doi = {10.3847/1538-4357/adb1d5}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {50}, shortjournal = {The Astrophys. J.}, title = {Fifteen years of m31* X-ray variability and flares}, volume = {981}, year = {2025}, }
• (2025). ALMA observations of peculiar embedded icy objects. ApJ, 981(1), 49. (www)

  @article{ , abstract = {We report the results of molecular line observations with the Atacama Large Millimeter/submillimeter Array (ALMA) toward two peculiar icy objects, which were discovered serendipitously by infrared spectroscopic survey of the Galactic plane with the AKARI satellite. Previous infrared observations have reported that both objects show deep ice and dust absorption features that are often seen in embedded young stellar objects (YSOs) or background stars sitting behind dense clouds; however, they are located neither in known star-forming regions nor in known dense clouds. Their infrared spectral energy distributions (SEDs) show peaks around 5 μ m, which are incompatible with existing SED models of typical embedded YSOs. The present ALMA observations have detected compact emission of CO(3–2) and SiO(8–7) at the positions of the icy objects. The observed large column ratios of gas-phase SiO/CO (∼10 −3 ) in both objects, as well as their broad line widths (8–14 km s −1 ), imply that they are associated with shocked gas. Although a large dust extinction ( A V ∼ 100 mag) is expected from their deep dust/ice absorption, no dust continuum emission is detected, which would suggest a large beam dilution effect due to their compact source sizes. Their systemic velocities are clearly separated from the surrounding CO clouds, suggesting that they are isolated. The characteristics of their SEDs, the presence of deep ice/dust absorption features, compact source size, and SiO-dominated broad molecular line emission cannot easily be accounted for by any of known interstellar ice-absorption sources. They may represent a previously unknown type of isolated icy objects.}, archive = {J_ApJ}, author = {Takashi Shimonishi and Takashi Onaka and Itsuki Sakon}, doi = {10.3847/1538-4357/ada4ad}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {49}, shortjournal = {The Astrophys. J.}, title = {ALMA observations of peculiar embedded icy objects}, volume = {981}, year = {2025}, }
• (2025). The radio counterpart to the fast X-ray transient EP240414a. ApJ, 981(1), 48. (www)

  @article{ , abstract = {Despite being operational for only a short time, the Einstein Probe mission, with its large field of view and rapid localization capabilities, has already significantly advanced the study of rapid variability in the soft X-ray sky. We report the discovery of luminous and variable radio emission from the Einstein Probe fast X-ray transient EP240414a, the second such source with a radio counterpart. The radio emission at 3 GHz peaks at ∼30 days postexplosion and with a spectral luminosity ∼2 × 10 30 erg s −1 Hz −1 , similar to what is seen from long gamma-ray bursts, and distinct from other extragalactic transients including supernovae and tidal disruption events, although we cannot completely rule out emission from engine driven stellar explosions, e.g., the fast blue optical transients. An equipartition analysis of our radio data reveals that an outflow with at least a moderate bulk Lorentz factor (Γ ≳ 1.6) with a minimum energy of ∼10 48 erg is required to explain our observations. The apparent lack of a reported gamma-ray counterpart to EP240414a could suggest that an off-axis or choked jet could be responsible for the radio emission, although a low-luminosity gamma-ray burst may have gone undetected. Our observations are consistent with the hypothesis that a significant fraction of extragalactic fast X-ray transients are associated with the deaths of massive stars.}, archive = {J_ApJ}, author = {Joe S. Bright and Francesco Carotenuto and Rob Fender and Carmen Choza and Andrew Mummery and Peter G. Jonker and Stephen J. Smartt and David R. DeBoer and Wael Farah and James Matthews and Alexander W. Pollak and Lauren Rhodes and Andrew Siemion}, doi = {10.3847/1538-4357/adaaef}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {48}, shortjournal = {The Astrophys. J.}, title = {The radio counterpart to the fast X-ray transient EP240414a}, volume = {981}, year = {2025}, }
• (2025). Spatial variations of stellar elemental abundances in FIRE simulations of milky way-mass galaxies: Patterns today mostly reflect those at formation. ApJ, 981(1), 47. (www)

  @article{ , abstract = {Spatial patterns of stellar elemental abundances encode rich information about a galaxy's formation history. We analyze the radial, vertical, and azimuthal variations of metals in stars, both today and at formation, in the FIRE-2 cosmological simulations of Milky Way (MW)-mass galaxies, and we compare them with the MW. The radial gradient today is steeper (more negative) for younger stars, which agrees with the MW, although radial gradients are shallower in FIRE-2. Importantly, this age dependence was present already at birth: radial gradients today are only modestly (≲0.01 dex kpc −1 ) shallower than at birth. Disk vertical settling gives rise to negative vertical gradients across all stars, but vertical gradients of mono-age stellar populations are weak. Similar to the MW, vertical gradients in FIRE-2 are shallower at larger radii, but they are overall shallower in FIRE-2. This vertical dependence was present already at birth: vertical gradients today are only modestly (≲0.1 dex kpc −1 ) shallower than at birth. Azimuthal scatter is nearly constant with radius, and it is nearly constant with age ≲8 Gyr ago but increases for older stars. Azimuthal scatter is slightly larger (≲0.04 dex) today than at formation. Galaxies with larger azimuthal scatter have a stronger radial gradient, implying that azimuthal scatter today arises primarily from the radial redistribution of gas and stars. Overall, spatial variations of stellar metallicities show only modest differences between formation and today; spatial variations today primarily reflect the conditions of stars at birth, with spatial redistribution of stars after birth contributing secondarily.}, archive = {J_ApJ}, author = {Russell L. Graf and Andrew Wetzel and Matthew A. Bellardini and Jeremy Bailin}, doi = {10.3847/1538-4357/adacd7}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {47}, shortjournal = {The Astrophys. J.}, title = {Spatial variations of stellar elemental abundances in FIRE simulations of milky way-mass galaxies: Patterns today mostly reflect those at formation}, volume = {981}, year = {2025}, }
• (2025). The structure of the molecular envelope of the ring nebula (NGC 6720). ApJ, 981(1), 46. (www)

  @article{ , abstract = {We present the first interferometric imaging of molecular line emission from the Ring Nebula, NGC 6720, in the form of Submillimeter Array (SMA) observations of CO J = 2 → 1 emission. The SMA 12 CO(2–1) mapping data, with ∼3'' spatial resolution and 2 km s −1 velocity resolution, provide an unprecedentedly detailed, 3D view of the Ring's clumpy molecular envelope. The emission morphology displayed in the velocity-integrated SMA 12 CO(2–1) image closely resembles the morphologies of near-IR H 2 and polycyclic aromatic hydrocarbon emission as revealed in recent JWST/NIRCam imaging of NGC 6720. The SMA 12 CO(2–1) data demonstrate that the molecular gas is found within a geometrically thin layer that immediately surrounds the ionized gas imaged by Hubble Space Telescope and JWST. A simple, geometric model of the 12 CO(2–1) emission data shows that the intrinsic structure of NGC 6720's molecular envelope closely resembles a truncated, triaxial ellipsoid that is viewed close to pole-on, and that the dynamical age of the molecular envelope is ∼6000 yr. The SMA 12 CO(2–1) mapping data furthermore reveal that some of the faint, filamentary features seen projected in the Ring's interior in JWST imaging are in fact fast-moving polar knots or bullets with radial velocities of ±45–50 km s −1 relative to the systemic velocity, and that the hot progenitor star remnant is positioned at the precise geometric center of the clumpy, ellipsoidal molecular shell. We assert that the Ring's molecular envelope represents the "fossil" remnant of a relatively sudden mass ejection ∼6000 yr ago that terminated the progenitor star's asymptotic giant branch (AGB) evolution, and that this ellipsoidal envelope of AGB ejecta was then punctured by fast, collimated polar outflows or jets resulting from interactions between the progenitor and one or more companion stars. Such an evolutionary scenario may describe most if not all molecule-rich, "Ring-like" planetary nebulae.}, archive = {J_ApJ}, author = {Joel H. Kastner and David J. Wilner and Diana Ryder and Paula Moraga Baez and Orsola De Marco and Raghvendra Sahai and Alwyn Wootten and Albert Zijlstra}, doi = {10.3847/1538-4357/adace1}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {46}, shortjournal = {The Astrophys. J.}, title = {The structure of the molecular envelope of the ring nebula (NGC 6720)}, volume = {981}, year = {2025}, }
• (2025). Bilateral constraints on proton lorentz violation effects. ApJ, 981(1), 45. (www)

  @article{ , abstract = {Since the early reports of events beyond the Greisen–Zatsepin–Kuzmin (GZK) cutoff, the investigation of ultrahigh-energy cosmic rays has emerged as a fundamental method for testing Lorentz invariance violation (LV) effects. Recent advances in observational capabilities have resulted in more stringent constraints on LV parameters. This study delves into the potentially anomalous phenomena arising from subluminal and superluminal LV effects, encompassing aspects such as proton decay and atypical threshold behavior of photo-pion production from protons within the GZK region. High-energy proton observations via cosmic rays have imposed stringent constraints on superluminal proton LV effects, while the confirmation of the GZK cutoff has established a robust boundary for the anomalous phenomena associated with subluminal proton LV effects. The research provides rigorously bilateral constraints on proton LV effects from both subluminal and superluminal standpoints.}, archive = {J_ApJ}, author = {Ping He and Bo-Qiang Ma}, doi = {10.3847/1538-4357/adad6c}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {45}, shortjournal = {The Astrophys. J.}, title = {Bilateral constraints on proton lorentz violation effects}, volume = {981}, year = {2025}, }
• (2025). Double layers in the martian magnetosheath. ApJ, 981(1), 44. (www)

  @article{ , abstract = {The observation of electrostatic double layers in Martian magnetosheath plasma is reported, based on medium-frequency (100 Hz–32 kHz) electric field data recorded by the Langmuir Probe and Waves on board the Mars Atmosphere and Volatile Evolution spacecraft on 2021 January 1. A total of six burst mode events were scrutinized, revealing the occurrence of double layer structures. Overall, 79 double layers were identified, with their absolute amplitudes and widths found to be in the ranges of 0.4–3.3 mV m −1 and 0.6–6.4 ms, respectively. The dominant frequency associated with the observed excitations lies well above the ion plasma frequency ( f pi ). The identified structures were observed at 2600–4400 km altitude in the dusk sector (17–19 LT). Extensive analysis based on a nonlinear multifluid plasma model shows that the observed structures are electron-acoustic double layers. A comparison of theory and observations indicates that these double layers have spatial scales in the range of 0.4–10 km. This is the first detailed study to give conclusive evidence of the occurrence of double layers in the Martian plasma environment.}, archive = {J_ApJ}, author = {Sahil Pandey and Amar Kakad and Bharati Kakad and Kuldeep Singh and Ioannis Kourakis}, doi = {10.3847/1538-4357/adad6f}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {44}, shortjournal = {The Astrophys. J.}, title = {Double layers in the martian magnetosheath}, volume = {981}, year = {2025}, }
• (2025). The puzzling superorbital period variation of the low-mass X-ray binary 4U 1820–30. ApJ, 981(1), 43. (www)

  @article{ , abstract = {Because of the previously observed stability of the 171 days period, the superorbital modulation of the low-mass X-ray binary 4U 1820–30 was considered a consequence of a third star orbiting around the binary. This study aims to further verify this triple model by testing the stability of the superorbital period using the light curves collected by X-ray sky-monitoring/scanning telescopes from 1987 to 2023. Both power spectral and phase analysis results indicate a significant change in the superorbital period, from 171 to 167 days, over this 36 yr span. The evolution of the superorbital phase suggests that the superorbital period may have experienced an abrupt change between early 2001 and mid 2003 or changed gradually with a period derivative of {\dot{P}}_{\sup }=(-4.20\pm 0.72)\times 1{0}^{-4} day day −1 . We conclude that the superorbital period of 4U 1820–30 was not as stable as anticipated by the triple model, which strongly challenges this hypothesis. Instead, we propose an irradiation-induced mass-transfer instability scenario to explain the superorbital modulation of 4U 1820–30.}, archive = {J_ApJ}, author = {Yi Chou and Jun-Lei Wu and Bo-Chun Chen and Wei-Yun Chang}, doi = {10.3847/1538-4357/adaded}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {43}, shortjournal = {The Astrophys. J.}, title = {The puzzling superorbital period variation of the low-mass X-ray binary 4U 1820–30}, volume = {981}, year = {2025}, }
• (2025). Effects of martian dust storms on ionospheric peak altitudes. ApJ, 981(1), 42. (www)

  @article{ , abstract = {The effects of Martian dust storms on the atmosphere and ionosphere is one of the hot topics in Mars research. This paper reports on the effects of a local dust storm on the ionospheric peak altitude based on electron density profile observations from the Mars Global Surveyor Radio Science experiment during a dust storm event in late 2004. By employing a profile fitting technique, we determined the peak altitudes of both the M1 and M2 layers. A statistical analysis of different dust storm phases was conducted in conjunction with changes in atmospheric dust opacity. The results indicate that during the phase of rapid increase in global opacity, the peak altitudes of the two layers are elevated differently. After the opacity reaches saturation, the peak altitudes start to decrease slowly, with distinct decreasing trends for each layer. This suggests that dust storms exert different effects across various altitudes within the Martian ionosphere and atmosphere, which require the introduction of new physical processes for explanation. The discussion of the relationship between opacity and peak altitude contributes to a deeper understanding of the dynamics by which dust storms influence the Martian atmosphere and ionosphere, offering new insights for dust storm observation and future forecasting efforts.}, archive = {J_ApJ}, author = {Yu Lou and Hong Zou and Yu Guang Ye and Jin Song Wang}, doi = {10.3847/1538-4357/adae01}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {42}, shortjournal = {The Astrophys. J.}, title = {Effects of martian dust storms on ionospheric peak altitudes}, volume = {981}, year = {2025}, }
• (2025). Considerations on the origin of IRAS 19312+1950 based on long-term maser observations. ApJ, 981(1), 41. (www)

  @article{ , abstract = {IRAS source 19312+1950 (hereafter I19312) is an infrared point source with maser emissions of SiO, H 2 O, and OH molecules. Although initial observations suggested that I19312 might be an evolved star, its characteristics are not fully consistent with this classification. This study aims to further investigate the nature of I19312 by conducting long-term monitoring of its maser emissions and comparing the results with other known astrophysical objects. We conducted long-term monitoring of SiO, H 2 O, and OH maser emissions using single-dish radio telescopes. The results were then compared with historical maser data and the characteristics of similar objects to infer the possible origin of I19312. The SiO maser emissions from I19312 were detected over a wide velocity range and exhibited significant time variability. The OH maser lines suggest characteristics of an evolved star, while the H 2 O maser lines indicate molecular outflows. These features suggest that I19312 could be a candidate for a water fountain star, though there are inconsistencies, such as the large molecular gas mass, that challenge this hypothesis. The possibility of I19312 being a red nova remnant (RNR) is also considered, but this remains speculative due to the lack of direct evidence. The evolutionary stage of I19312 remains unclear, but it shares multiple characteristics with both evolved stars with peculiar properties and RNRs. Further long-term monitoring and high-resolution interferometric observations are required to better constrain the nature of this object.}, archive = {J_ApJ}, author = {Huan-Xue Feng and Jun-ichi Nakashima and D. Engels and S. Etoka and Jaeheon Kim and Yong Zhang and Jia-Yong Xie and Jian-Jie Qiu}, doi = {10.3847/1538-4357/adae09}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {41}, shortjournal = {The Astrophys. J.}, title = {Considerations on the origin of IRAS 19312+1950 based on long-term maser observations}, volume = {981}, year = {2025}, }
• (2025). On a critical acceleration scale of dark matter in ΛCDM and dynamical dark energy. ApJ, 981(1), 40. (www)

  @article{ , abstract = {Universal acceleration a 0 emerges in various empirical laws, yet its fundamental nature remains unclear. Using Illustris and Virgo N -body simulations, we focus on the velocity and acceleration fluctuations in collisionless dark matter involving long-range gravity. For comparison, in the kinetic theory of gases, molecules undergo random elastic collisions involving short-range interactions, where only velocity fluctuations are relevant. Hierarchical structure formation proceeds through the merging of smaller halos to form larger halos, which facilitates a continuous energy cascade from small to large halos at a constant rate ε u ≈ −10 −7 m 2 s −3 . Velocity fluctuations involve a critical velocity u c ∝ (1 + z ) −3/4 . Acceleration fluctuations involve a critical acceleration a c ∝ (1 + z ) 3/4 . Two critical quantities are related by the rate of energy cascade ε u ≈ − a c u c /[2(3 π ) 2 ], where factor 3 π is from the angle of incidence during merging. With critical velocity u c on the order of 300 km s −1 at z = 0, the critical acceleration is determined to be a c 0 ≡ a c ( z = 0) ≈ 10 −10 m s −2 , suggesting a c might explain the universal acceleration a 0 ≈ 10 −10 m s −2 in the empirical Tully–Fisher relation or modified Newtonian dynamics. The redshift evolution a c ∝ (1 + z ) 3/4 is in good agreement with Magneticum and EAGLE simulations and in reasonable agreement with limited observations. This suggests a larger a 0 at a higher redshift such that galaxies of fixed mass rotate faster at a higher redshift. Note that for dark energy (DE) density {\rho }_{\mathrm{DE}0}\approx {a}_{c0}^{2}/G=1{0}^{-10} J m −3 , we postulate an entropic origin of the DE from acceleration fluctuations of dark matter, analogous to the gas pressure from velocity fluctuations. This leads to a dynamical DE coupled to the structure evolution involving a relatively constant DE density followed by a slow weakening phase, suggesting possible deviations from the standard ΛCDM paradigm.}, archive = {J_ApJ}, author = {Zhijie Xu}, doi = {10.3847/1538-4357/adaeb3}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {40}, shortjournal = {The Astrophys. J.}, title = {On a critical acceleration scale of dark matter in ΛCDM and dynamical dark energy}, volume = {981}, year = {2025}, }
• (2025). A very long baseline interferometry calibrator grid at 600 MHz for fast radio transient localizations with CHIME/FRB outriggers. ApJ, 981(1), 39. (www)

  @article{ , abstract = {The Canadian Hydrogen Intensity Mapping Experiment Fast Radio Burst (CHIME/FRB) Project has a new very long baseline interferometry (VLBI) Outrigger at the Green Bank Observatory (GBO), which forms a 3300 km baseline with CHIME operating at 400–800 MHz. Using 100 ms long full-array baseband "snapshots" collected commensally during FRB and pulsar triggers, we perform a shallow, wide-area VLBI survey covering a significant fraction of the northern sky targeted at the positions of compact sources from the Radio Fundamental Catalog. In addition, our survey contains calibrators detected from two 1 s long trial baseband snapshots for a deeper survey with CHIME and GBO. In this paper, we present the largest catalogue of compact calibrators suitable for 30 mas scale VLBI observations at subgigahertz frequencies to date. Our catalogue consists of 200 total calibrators in the Northern Hemisphere that are compact on 30 mas scales with fluxes above 100 mJy. This calibrator grid will enable the precise localization of hundreds of FRBs a year with CHIME/FRB Outriggers.}, archive = {J_ApJ}, author = {Shion Andrew and Calvin Leung and Alexander Li and Kiyoshi W. Masui and Bridget C. Andersen and Kevin Bandura and Alice P. Curtin and Jane Kaczmarek and Adam E. Lanman and Mattias Lazda and Juan Mena-Parra and Daniele Michilli and Kenzie Nimmo and Aaron B. Pearlman and Mubdi Rahman and Vishwangi Shah and Kaitlyn Shin and Haochen Wang and (CHIME/FRB Collaboration)}, doi = {10.3847/1538-4357/adaf8d}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {39}, shortjournal = {The Astrophys. J.}, title = {A very long baseline interferometry calibrator grid at 600 MHz for fast radio transient localizations with CHIME/FRB outriggers}, volume = {981}, year = {2025}, }
• (2025). GECKO follow-up observations of the binary neutron Star–Black hole merger candidate s230518h. ApJ, 981(1), 38. (www)

  @article{ , abstract = {The gravitational-wave (GW) event S230518h is a potential binary neutron star–black hole merger (NSBH) event that was detected during engineering run 15, which served as the commissioning period before the LIGO–Virgo–KAGRA O4a observing run. Despite its low probability of producing detectable electromagnetic emissions, we performed extensive follow-up observations of this event using the Gravitational-wave Electromagnetic Counterpart Korean Observatories (GECKO) telescopes in the Southern Hemisphere. Our observations covered 61.7% of the 90% credible region, a 284 deg 2 area accessible from the Southern Hemisphere, reaching a median limiting magnitude of R = 21.6 mag. In these images, we conducted a systematic search for an optical counterpart of this event by combining a convolutional-neural-network-based classifier and human verification. We identified 128 transient candidates, but no significant optical counterpart was found that could have caused the GW signal. Furthermore, we provide feasible kilonova properties that are consistent with the upper limits of the observations. Although no optical counterpart was found, our result demonstrates both GECKO's efficient wide-field follow-up capabilities and usefulness for constraining properties of kilonovae from NSBH mergers at distances of ∼200 Mpc.}, archive = {J_ApJ}, author = {Gregory S. H. Paek and Myungshin Im and Mankeun Jeong and Seo-Won Chang and Martin Moonkuk Hur and YoungPyo Hong and Sophia Kim and Jaewon Lee and Dongjin Lee and Seong-Heon Lee and Jae-Hun Jung and Joonho Kim and Hyung Mok Lee and Chung-Uk Lee and Seung-Lee Kim}, doi = {10.3847/1538-4357/adaf99}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {38}, shortjournal = {The Astrophys. J.}, title = {GECKO follow-up observations of the binary neutron Star–Black hole merger candidate s230518h}, volume = {981}, year = {2025}, }
• (2025). Prediction of halo coronal mass ejections using SDO/HMI vector magnetic data products and a transformer model. ApJ, 981(1), 37. (www)

  @article{ , abstract = {We present a transformer model, named DeepHalo, to predict the occurrence of halo coronal mass ejections (CMEs). Our model takes as input an active region (AR) and a profile, where the profile contains a time series of data samples in the AR that are collected 24 hr before the beginning of a day, and predicts whether the AR would produce a halo CME during that day. Each data sample contains physical parameters, or features, derived from photospheric vector magnetic field data taken by the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory. We survey and match CME events in the Space Weather Database Of Notification, Knowledge, Information and the Large Angle and Spectrometric Coronagraph CME Catalog, and we compile a list of CMEs, including halo CMEs and nonhalo CMEs, associated with ARs in the period between 2010 November and 2023 August. We use the information gathered above to build the labels (positive vs. negative) of the data samples and profiles at hand, where the labels are needed for machine learning. Experimental results show that DeepHalo with a true skill statistic (TSS) score of 0.907 outperforms a closely related long short-term memory network with a TSS score of 0.821. To our knowledge, this is the first time that the transformer model has been used for halo CME prediction.}, archive = {J_ApJ}, author = {Hongyang Zhang and Ju Jing and Jason T. L. Wang and Haimin Wang and Yasser Abduallah and Yan Xu and Khalid A. Alobaid and Hameedullah Farooki and Vasyl Yurchyshyn}, doi = {10.3847/1538-4357/adafa0}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {37}, shortjournal = {The Astrophys. J.}, title = {Prediction of halo coronal mass ejections using SDO/HMI vector magnetic data products and a transformer model}, volume = {981}, year = {2025}, }
• (2025). Inverse raman scattering and the diffuse interstellar bands: An exploration of the systemic interconnections between spontaneous and inverse raman scattering and extended red emission, red rectangle bands, and diffuse interstellar bands. ApJ, 981(1), 36. (www)

  @article{ , abstract = {First identified in 1964, inverse Raman scattering (IRS) is a nonlinear stimulated phenomenon that induces Raman-scattered absorptions where Raman emissions would be expected. This paper highlights the significance of IRS in analyzing the spectra of stars located in the distant background of H I interstellar clouds. Specifically, ultraviolet emission lines Raman scattered by atomic hydrogen, typically observed in emission at wide scattering angles in the optical spectra of symbiotic stars and nebulae, should appear as IRS absorptions in the optical spectra of the background stars. I show that all known interstellar Raman-scattered emission lines in the H α wavelength region are detected in absorption as diffuse interstellar bands (DIBs) in the spectra of reddened stars, and conclude that IRS by atomic hydrogen resolves the long-standing DIB puzzle. This sheds new light on the perplexing relationship between DIBs and the Red Rectangle nebula emission bands (RRBs). The conditions under which either DIBs or RRBs are detected emphasize the importance of considering the physical relationship between the observer, the H I medium, and the direction of the illuminating radiation field (i.e., the geometry of the observation) in observations of H I interstellar matter. Observing in the direction of the radiation field or on its side determines whether IRS, yielding DIBs and the 2200 Å bump, or spontaneous Raman scattering at wide scattering angles, resulting in extended red emission, Raman-scattered emission lines (including RRBs), and unidentified infrared bands, will be observed.}, archive = {J_ApJ}, author = {Frédéric Zagury}, doi = {10.3847/1538-4357/adb0cc}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {36}, shortjournal = {The Astrophys. J.}, title = {Inverse raman scattering and the diffuse interstellar bands: An exploration of the systemic interconnections between spontaneous and inverse raman scattering and extended red emission, red rectangle bands, and diffuse interstellar bands}, volume = {981}, year = {2025}, }
• (2025). Helium pickup ion velocity distributions observed in interplanetary coronal mass ejection structures. ApJ, 981(1), 35. (www)

  @article{ , abstract = {The velocity distribution functions (VDFs) of He + pickup ions (PUIs) through two interplanetary coronal mass ejection (ICME) events associated with two interplanetary shocks are examined. Their specific properties in pitch-angle space were used as tracers of the local physical processes. These VDFs were studied using observations from the PLasma And SupraThermal Ion Composition instrument on board the Solar Terrestrial Relations Observatory with 10 minutes cadence and full energy and angular resolutions. The analysis focuses on pitch angle distributions and their average/deviation to evaluate heating/cooling, acceleration/deceleration, and pitch angle diffusion. For an ICME accompanied by the quasi-perpendicular shock, (a) reflected and energized particles were found in the upstream, and pitch angle scattering and suprathermal particle production were conspicuous in the downstream; (b) strong heating was observed in the sheath region; (c) suprathermal particles were found in the sheath region and attributed to the velocity fluctuation within the solar wind; and (d) universal pitch angle scattering was found throughout the ICME. For an ICME accompanied by a quasi-parallel shock, (a) localized heating and acceleration were found around the shock location; (b) power-law suprathermal tail distributions were found near the shock, suggesting diffusive shock acceleration processes; (c) weak or no sheath heating was observed; and (d) pitch angle scattering was correlated with magnetic field power spectral density. In the magnetic cloud for this event, pitch angle diffusion consistent with the scattering by counterpropagating Alfvén waves was found. This type of analysis can be applied to study shock injection processes and PUI transport/diffusion processes under active conditions.}, archive = {J_ApJ}, author = {Keiichi Ogasawara and Maher A. Dayeh and Robert W. Ebert and Berndt Klecker and Harald Kucharek}, doi = {10.3847/1538-4357/adb1b4}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {35}, shortjournal = {The Astrophys. J.}, title = {Helium pickup ion velocity distributions observed in interplanetary coronal mass ejection structures}, volume = {981}, year = {2025}, }
• (2025). Magnetic interactions in white dwarf binaries as mechanism for long-period radio transients. ApJ, 981(1), 34. (www)

  @article{ , abstract = {A growing population of long-period radio transients has been discovered, and their physical origin is still up for debate. Recently, a new such source named ILT J1101+5521 was discovered, which is in a white dwarf (WD)–red dwarf (RD) binary system, with the observed 125.5 minutes period in radio emission being identified as the orbital period and the radio emission occurs at the inferior conjunction of the WD. We suggest that the radio emission properties of the system can be well explained within the framework of the unipolar inductor magnetic interaction model between the magnetized WD and the RD with low magnetization, with a relativistic version of electron cyclotron maser emission being the most likely radiation mechanism. We suggest that this mechanism can interpret at least some long-period radio transients, especially the ultra-long-period subpopulation. Within this model, high energy emission in X-rays via relativistically boosted cyclotron radiation and γ -rays via inverse Compton scattering off stellar light are expected, but the predicted luminosities are relatively low. This model likely applies to the ultra-long-period population of LPRTs. The short-period population of LPRTs is likely powered by other engines, such as slow magnetars.}, archive = {J_ApJ}, author = {Yuanhong Qu and Bing Zhang}, doi = {10.3847/1538-4357/adb1b5}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {34}, shortjournal = {The Astrophys. J.}, title = {Magnetic interactions in white dwarf binaries as mechanism for long-period radio transients}, volume = {981}, year = {2025}, }
• (2025). The GeV γ-ray emission from the composite supernova remnant CTB 87. ApJ, 981(1), 33. (www)

  @article{ , abstract = {We report the GeV γ -ray emission around the composite supernova remnant (SNR) CTB 87 with more than 16 yr of PASS 8 data recorded by the Fermi Large Area Telescope. Two separate point sources with different GeV spectra are identified in this region: one has a soft γ -ray spectrum, likely due to interactions between the SNR shock and molecular clouds, and another source with a hard GeV γ -ray spectrum aligns with the TeV spectrum of VER J2016+371, suggesting it as the GeV counterpart. Considering the observations of CTB 87 in the radio and X-ray bands, VER J2016+371 is proposed to originate from the pulsar wind nebula (PWN) associated with PSR J2016+3711. A leptonic model with a broken power-law electron distribution could explain the multiwavelength data of VER J2016+371, with fitted parameters matching typical γ -ray PWNe. Deeper searching for the SNR shock of CTB 87 in other bands and the future TeV observations by LHAASO and Cherenkov Telescope Array are crucial to reveal the nature of CTB 87.}, archive = {J_ApJ}, author = {Yuliang Xin and Jian Tang and Weixiong Ding and Xi Liu and Yunfeng Zhang and Xiaolei Guo}, doi = {10.3847/1538-4357/adb282}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {33}, shortjournal = {The Astrophys. J.}, title = {The GeV γ-ray emission from the composite supernova remnant CTB 87}, volume = {981}, year = {2025}, }
• (2025). Chicago–Carnegie hubble program: A multiwavelength search for the effects of metallicity on the cepheid distance scale. II. theoretical models and synthetic spectra. ApJ, 981(1), 32. (www)

  @article{ , abstract = {This is the second of two papers exploring the effects of metallicity on the multiwavelength properties of Cepheids in terms of their multiwavelength period–luminosity (PL) relations, impacting their use as extragalactic distance indicators and underpinning one of the most popular paths to estimating the expansion rate of the Universe, H 0 . In Paper I, we presented five tests for the influence of metallicity on galactic and extragalactic Cepheid PL relations, spanning nearly 2 dex in metallicity and inspecting PL relations from the optical ( BVI ), through the near-infrared ( JHK ), and into the mid-infrared (at 3.4 and 4.5 μ m). And in no case were any statistically significant results forthcoming. Here we interrogate published spectral energy distributions constructed from theoretical (static) stellar atmospheres, covering the surface gravity and temperature ranges attributed to classical (supergiant, F and K spectral type) Cepheid variables, and explore the differential effects of changing the atmospheric metallicity, down by 2 dex from solar (a factor of 100 below the average Milky Way value) and then up from solar by 0.5 dex (i.e., a factor of 3 × above the Milky Way value). The theoretical models clearly show that metallicity systematically impacts each of the bandpasses differentially: the level of this effect is largest in the ultraviolet (where line blanketing is most intense), reversing sign in the optical (due to flux redistribution from the UV), and then asymptotically falling back to zero from the red to the far-infrared. The discovered effects of metallicity are systematic, but they are small, and as such, they do not contradict the findings of Paper I, but they do explain why the problem has been so hard to resolve given the low level of precision of the photometry for all but the very nearest and apparently brightest Cepheids. The most interesting (and useful) result of this investigation is that from a close examination of the models, we have discovered infrared regions in Cepheid spectral energy distributions that allow for the simultaneous correction for extinction and metallicity differences by the judicious combination of only two filters: one in the near-infrared and one in the mid-infrared, the former centered at 1.2 μ m and the other centered at 3.6 μ m. Even more exciting and promising is the fact that both of these bands can be simultaneously observed in single exposures using the dual-channel imager, NIRCam on JWST.}, archive = {J_ApJ}, author = {Barry F. Madore and Wendy L. Freedman and Kayla Owens}, doi = {10.3847/1538-4357/ada3d5}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {32}, shortjournal = {The Astrophys. J.}, title = {Chicago–Carnegie hubble program: A multiwavelength search for the effects of metallicity on the cepheid distance scale. II. theoretical models and synthetic spectra}, volume = {981}, year = {2025}, }
• (2025). Sloan digital sky survey IV MaStar: Quantification and abatement of interstellar absorption in the largest empirical stellar spectral library. ApJ, 981(1), 31. (www)

  @article{ , abstract = {We assess the impact of Ca ii λ λ 3934, 3969 and Na i λ λ 5891, 5897 absorption arising in the interstellar medium (ISM) on the Sloan Digital Sky Survey-IV MaNGA Stellar Library (MaStar) and produce corrected spectroscopy for 80% of the 24,162-star catalog. We model the absorption strength of these transitions as a function of the stellar distance, Galactic latitude, and dust reddening based on high-spectral resolution studies. With this model, we identify 6342 MaStar stars that have negligible ISM absorption ( W ISM (Ca ii K) < 0.07 Å and W ISM (Na i 5891) < 0.05 Å). For 12,110 of the remaining stars, we replace their Na i D profile (and their Ca ii profile for effective temperatures T eff > 9000 K) with a coadded spectrum of low-ISM stars with similar T eff , surface gravity, and metallicity. For 738 additional stars with T eff > 9000 K, we replace these spectral regions with a matching ATLAS9-based BOSZ model. This results in a mean reduction in W (Ca ii K) ( W (Na i D)) of 0.4–0.7 Å (0.6–1.1 Å) for hot stars ( T eff > 7610 K), and a mean reduction in W (Na i D) of 0.1–0.2 Å for cooler stars. We show that interstellar absorption in the simple stellar population (SSP) model spectra constructed from the original library artificially enhances W (Ca ii K) by ≳20% at young ages (<400 Myr); dramatically enhances the strength of stellar Na i D in starbursting systems (by ≳50%); and enhances stellar Na i D in older stellar populations (≳10 Gyr) by ≳10%. We provide SSP spectra constructed from the cleaned library and discuss the implications of these effects for stellar population synthesis analyses constraining the stellar age, [Na/Fe] abundance, and initial mass function.}, archive = {J_ApJ}, author = {Kate H. R. Rubin and Kyle B. Westfall and Claudia Maraston and Daniel Thomas and Renbin Yan and J. Christopher Howk and Erick Aguirre and Kaelee S. Parker and David R. Law}, doi = {10.3847/1538-4357/ad8eb6}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {31}, shortjournal = {The Astrophys. J.}, title = {Sloan digital sky survey IV MaStar: Quantification and abatement of interstellar absorption in the largest empirical stellar spectral library}, volume = {981}, year = {2025}, }
• (2025). The protostars in orion: Characterizing the properties of their magnetized envelopes. ApJ, 981(1), 30. (www)

  @article{ , abstract = {We present a study connecting the physical properties of protostellar envelopes to the morphology of the envelope-scale magnetic field. We used the Atacama Large Millimeter/submillimeter Array (ALMA) polarization observations of 61 young protostars at 0.87 mm on ~400–3000 au scales from the B -field Orion Protostellar Survey to infer the envelope-scale magnetic field, and we used the dust emission to measure the envelope properties on comparable scales. We find that protostars showing standard hourglass magnetic field morphology tend to have larger masses, and the nonthermal velocity dispersion is positively correlated with the bolometric luminosity and dust temperature of the envelope. Combining with the disk properties taken from the Orion VLA/ALMA Nascent Disk and Multiplicity survey, we connect envelope properties to fragmentation. Our results show a positive correlation between the fragmentation level and the angle dispersion of the magnetic field, suggesting that the envelope fragmentation tends to be suppressed by the magnetic field. We also find that protostars exhibiting standard hourglass magnetic field structure tend to have a smaller disk and smaller angle dispersion of the magnetic field than other field configurations, especially the rotated hourglass, but also the spiral and others, suggesting a more effective magnetic braking in the standard hourglass morphology of magnetic fields. Nevertheless, significant misalignment between the magnetic field and outflow axes tends to reduce magnetic braking, leading to the formation of larger disks.}, archive = {J_ApJ}, author = {Bo Huang and Josep M. Girart and Ian W. Stephens and Manuel Fernández López and Philip C. Myers and Qizhou Zhang and John J. Tobin and Paulo Cortes and Nadia M. Murillo and Sarah Sadavoy and Hector G. Arce and John M. Carpenter and Woojin Kwon and Valentin J. M. Le Gouellec and Zhi-Yun Li and Leslie W. Looney and Tom Megeath and Erin G. Cox and Nicole Karnath and Dominique Segura-Cox}, doi = {10.3847/1538-4357/ad9ea4}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {30}, shortjournal = {The Astrophys. J.}, title = {The protostars in orion: Characterizing the properties of their magnetized envelopes}, volume = {981}, year = {2025}, }
• (2025). Modeling the UV to radio spectral energy distribution of NGC 6946: Star formation rates and dust attenuation properties. ApJ, 981(1), 29. (www)

  @article{ , abstract = {In this paper, we perform an ultraviolet (UV) to radio spectral energy distribution fitting analysis of star-forming regions in the nearby galaxy NGC 6946 by means of the Graphite and Silicates ( GRASIL ) population synthesis and radiative transfer model to which the first version of the thoroughly updated Padova and Trieste Stellar Evolutionary Code (PARSEC v1.2s) database of evolutionary nonrotating tracks of massive stars is incorporated. The tracks span a wide range of initial chemical compositions ( Z = 0.0001–0.04) and stellar initial mass function (IMF) upper mass limits ( M up = 40 M ⊙ –350 M ⊙ ). We obtain from our best-fit models consistent and robust estimates of star formation rate calibrations at wavelengths ranging from UV to radio and as a function of IMF upper mass limit. We investigate the properties of dust attenuation curves that also result from the best-fit models by exploiting the realistic treatment of dust performed by GRASIL . This resulted in new relations between optical emission fluxes that are subject to attenuation and fluxes that are not prone to attenuation. These relations, which we show to be almost independent of IMF upper mass limits, can be extremely useful in estimating attenuations in young high redshift galaxies.}, archive = {J_ApJ}, author = {Ikechukwu A. Obi and Pius N. Okeke and Bonaventure I. Okere}, doi = {10.3847/1538-4357/ada957}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {29}, shortjournal = {The Astrophys. J.}, title = {Modeling the UV to radio spectral energy distribution of NGC 6946: Star formation rates and dust attenuation properties}, volume = {981}, year = {2025}, }
• (2025). NgVLA synthetic observations of ionized gas in massive protostars. ApJ, 981(1), 28. (www)

  @article{ , abstract = {Massive-star formation involves significant ionization in the innermost regions near the central object, such as gravitationally trapped H ii regions, jets, ionized disks, or winds. Resolved observations of the associated continuum and recombination line emission are crucial for guiding theory. The next-generation Very Large Array (ngVLA) will enable unprecedented observations of thermal emission with 1 mas resolution, providing a new perspective on massive-star formation at scales down to a few astronomical units at kiloparsec distances. This work presents synthetic interferometric ngVLA observations of the free–free continuum (93 GHz band), H41 α , and H38 α recombination lines from ionized jets and disks around massive protostars. Using the sf3dmodels Python package, we generate gas distributions based on analytical models, which are then processed through the RADMC-3D radiative transfer code. Our results indicate that the ngVLA can easily resolve, both spatially and spectrally, the ionized jet from a 15 M ⊙ protostar at 700 pc, distinguishing between collimated jets and wide-angle winds, and resolving their launching radii, widths, and any substructure down to a few astronomical units. Detailed studies of radio jets launched by massive protostars will be feasible up to distances of ​​​​​​∼2 kpc. Furthermore, ngVLA will be able to study in detail the ionized disks around massive (>10 M ⊙ ) protostars up to distances from 4 to 12 kpc, resolving their kinematics and enabling the measurement of their central masses across the Galaxy. These observations can be conducted with on-source integrations of only a few hours.}, archive = {J_ApJ}, author = {Jesús M. Jáquez-Domínguez and Roberto Galván-Madrid and Alfonso Trejo-Cruz and Carlos Carrasco-González and Jacopo Fritz and Susana Lizano and Aina Palau and Andrés F. Izquierdo and Luis F. Rodríguez and Alice Pasetto and Stanley Kurtz and Thomas Peters and Eric F. Jiménez-Andrade and Luis A. Zapata}, doi = {10.3847/1538-4357/adabe4}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {28}, shortjournal = {The Astrophys. J.}, title = {NgVLA synthetic observations of ionized gas in massive protostars}, volume = {981}, year = {2025}, }
• (2025). A sea of black holes: Characterizing the LISA signature for stellar-origin black hole binaries. ApJ, 981(1), 27. (www)

  @article{ , abstract = {Observations by the LIGO, Virgo, and KAGRA (LVK) detectors have provided new insights into the demographics of stellar-origin black hole binaries (sBHBs). A few years before gravitational-wave signals from sBHB mergers are recorded in the LVK detectors, their early coalescence will leave a unique signature in the ESA/NASA mission Laser Interferometer Space Antenna (LISA). Multiband observations of sBHB sources between the LISA and LVK detectors opens an unprecedented opportunity to investigate the astrophysical environment and multimessenger early alerts. In this study, we report the sBHB sources that are expected to be present in the LISA data derived directly from the hydrodynamic cosmological simulation Illustris. By surveying snapshots across cosmological volume, metallicity, and lookback time, we calculate the expected sBHBs present in the LISA data for various combinations of mission lifetimes and stellar population models. For stellar population estimates consistent with the LVK rates, we find that only 10 sBHBs across the Illustris snapshots would be detected with significant confidence for a 10 yr LISA mission, while a 4 yr LISA mission would detect only  ∼1 sBHB. Our work paves the way for creating LISA mock data and benchmarking LISA detection pipelines directly using cosmological simulations.}, archive = {J_ApJ}, author = {Krystal Ruiz-Rocha and Kelly Holley-Bockelmann and Karan Jani and Michela Mapelli and Samuel Dunham and William Gabella}, doi = {10.3847/1538-4357/adad6b}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {27}, shortjournal = {The Astrophys. J.}, title = {A sea of black holes: Characterizing the LISA signature for stellar-origin black hole binaries}, volume = {981}, year = {2025}, }
• (2025). Evolution of X-ray gas in SN 1987A from 2007 to 2021: Ring fading and ejecta brightening unveiled through differential emission measure analysis. ApJ, 981(1), 26. (www)

  @article{ , abstract = {As the nearest supernova (SN) observed since Kepler's SN of 1604, SN 1987A provides an unprecedented opportunity to study in detail the early evolution of supernova remnants. Despite extensive studies through both observations and simulations, there is still an urgent need for a more effective approach to integrate the results from two sides. In this study, we conducted a detailed differential emission measure (DEM) analysis on the XMM-Newton observations taken in 2007 to 2021 to characterize the continuous temperature structure of SN 1987A, which can be better compared with simulations. The X-ray plasma exhibits a temperature distribution with a major peak at ∼0.5–1 keV and a high-temperature tail extending to ≳5 keV. The emission measure (EM) of the major peak started to decline around 2014, while the EM of the tail continued increasing and appears to have formed a secondary peak at ∼3–5 keV in recent years. Our DEM results are consistent with simulations, which help to further identify the major peak as originating from the equatorial ring and the secondary peak as arising from the newly shocked ejecta. Together with the simulations, our DEM analysis reveals recent fading of the ring and brightening of the ejecta in X-rays from SN 1987A. Additionally, we observed a recent decrease in the centroid energy of the Fe K line, providing further evidence of newly shocked ejecta.}, archive = {J_ApJ}, author = {Lei Sun and Salvatore Orlando and Emanuele Greco and Marco Miceli and Yang Chen and Jacco Vink and Ping Zhou}, doi = {10.3847/1538-4357/adaea7}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {26}, shortjournal = {The Astrophys. J.}, title = {Evolution of X-ray gas in SN 1987A from 2007 to 2021: Ring fading and ejecta brightening unveiled through differential emission measure analysis}, volume = {981}, year = {2025}, }
• (2025). Active galactic nucleus feedback in quiescent galaxies at cosmic noon traced by ionized gas emission. ApJ, 981(1), 25. (www)

  @article{ , abstract = {We analyze ionized gas emission lines in deep rest-frame optical spectra of 14 massive ( \mathrm{log}{M}_{* }\gt 10.2 M ⊙ ) quiescent galaxies at redshifts 1.7 < z < 3.5 observed with JWST/NIRSpec by the Blue Jay survey. Robust detection of emission lines in 71% of the sample indicates the presence of ongoing ionizing sources in this passive population. The H α line luminosities confirm that the population is quiescent, with star formation rates that are at least 10 times lower than the main sequence of star formation at z ∼ 2. The quiescent sample is clearly separate from the star-forming population in line diagnostic diagrams, and occupies a region usually populated by active galactic nuclei (AGN). Analysis of the observed line ratios, equivalent widths, and velocity dispersions leads us to conclude that in most cases the gas is ionized by AGN activity, despite the lack of X-ray detections. We measure generally low values of the bolometric luminosity L bol ∼ 10 44 erg s −1 and Eddington ratio λ ∼ 10 −2 –10 −3 for the central engines, typical of low-luminosity AGN. A subset of the sample also hosts ionized and neutral outflows, with ionized outflow velocities of the order of ∼1000 km s −1 . Our results show, for the first time using a representative sample, that low-luminosity AGN are extremely common among quiescent galaxies at high redshift. These low-luminosity AGN may play a key role in quenching star formation and in maintaining massive galaxies quiescent from Cosmic Noon to z ∼ 0.}, archive = {J_ApJ}, author = {Letizia Bugiani and Sirio Belli and Minjung Park and Rebecca L. Davies and J. Trevor Mendel and Benjamin D. Johnson and Amir H. Khoram and Chloë Benton and Andrea Cimatti and Charlie Conroy and Razieh Emami and Joel Leja and Yijia Li and Gabriel Maheson and Elijah P. Mathews and Rohan P. Naidu and Erica J. Nelson and Sandro Tacchella and Bryan A. Terrazas and Rainer Weinberger}, doi = {10.3847/1538-4357/adaeaf}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {25}, shortjournal = {The Astrophys. J.}, title = {Active galactic nucleus feedback in quiescent galaxies at cosmic noon traced by ionized gas emission}, volume = {981}, year = {2025}, }
• (2025). Reinvestigation of fast radio burst host galaxy and event rate density. ApJ, 981(1), 24. (www)

  @article{ , abstract = {Fast radio bursts (FRBs) are radio signals that last milliseconds. They originate from cosmological distances and have relatively high dispersion measures (DMs), making them excellent distance indicators. However, the origins of the FRB remain to be resolved. With its wide field of view and excellent sensitivity, CHIME/FRB has discovered more than half of all known FRBs. As more and more FRBs are located within or connected with their host galaxies, the study of FRB progenitors is becoming more important. In this work, we collect the currently available information related to the host galaxies of FRBs, and the Markov Chain Monte Carlo analysis about limited localized samples reveals no significant difference in the median of DM host between repeaters and nonrepeaters. After examining and selecting CHIME/FRB samples, we estimate the local volumetric rate density of repeaters and nonrepeaters, accounting for different DM host contributions, and compare with rates of predicted origin models and transient events. Our results indicate that DM host significantly affects volumetric rates and offer insights into the origin mechanisms of FRB populations.}, archive = {J_ApJ}, author = {W. Q. Ma and Z. F. Gao and B. P. Li and C. H. Niu and J. M. Yao and F. Y. Wang}, doi = {10.3847/1538-4357/adaf19}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {24}, shortjournal = {The Astrophys. J.}, title = {Reinvestigation of fast radio burst host galaxy and event rate density}, volume = {981}, year = {2025}, }
• (2025). Tidal disruptions of stars by supermassive and intermediate-mass black hole binaries: The effects of the first-order post-newtonian cross terms. ApJ, 981(1), 23. (www)

  @article{ , abstract = {In the vicinity of galactic nuclei, stars orbiting supermassive black hole (SMBH) binaries can undergo tidal disruption events (TDEs) due to the Lidov–Kozai mechanism and three-body interactions. While numerical simulations have incorporated post-Newtonian (PN) corrections up to 2.5PN order, they have not accounted for the 1PN cross-term effects among the three bodies. In this study, we employ N -body simulations to investigate the impact of the 1PN cross terms on the orbits of stars around an intermediate-mass black hole (IMBH) perturbed by an outer SMBH. Our findings indicate that while the 1PN cross terms do not substantially affect the fractions of stellar outcomes, they can cause considerable variations in the orbits of stars around IMBH–SMBH binaries. Specifically, we find that the inclusion of the 1PN cross terms can lead to more concentrated distributions of semimajor axes. Furthermore, we observe heavy tails in the distributions of temporal shifts in TDEs when these cross terms are included, with the maximum change reaching about 10 6 yr, approaching the maximum integration time of this study. This investigation underscores the critical importance of incorporating the 1PN cross terms to ensure accuracy in comprehensive simulations of multibody systems in galactic nuclei. Notably, for stars partially disrupted by an SMBH binary, omitting these cross terms could result in erroneous predictions.}, archive = {J_ApJ}, author = {Xiao-Jun Wu and Yan Luo and Jie Li and Ye-Fei Yuan and Wenbin Lin}, doi = {10.3847/1538-4357/adb1bb}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {23}, shortjournal = {The Astrophys. J.}, title = {Tidal disruptions of stars by supermassive and intermediate-mass black hole binaries: The effects of the first-order post-newtonian cross terms}, volume = {981}, year = {2025}, }
• (2025). Stochastic acceleration in weakly turbulent astrophysical environments. ApJ, 981(1), 22. (www)

  @article{ , abstract = {Turbulent magnetic fields are to some extent a universal feature in astrophysical phenomena. Charged particles that encounter this turbulence are typically accelerated according to the so-called second-order Fermi process. However, in most astrophysical environments there are additional competing processes, such as different kinds of first-order energy changes and particle escape, that affect the resulting momentum distribution of the particles. In this work we provide to our knowledge the first semianalytical solution of the isotropic steady-state momentum diffusion equation including continuous and catastrophic momentum changes that can be applied to any astrophysical system of interest that is under the influence of weak magnetic turbulence. Here, we adopt that the assigned magnetic turbulence is constrained to a finite range and the particle flux vanishes beyond these boundaries. Consequently, we show that the so-called pile-up bump—which has long been established for some special cases—is a universal feature of stochastic acceleration that emerges around the momentum χ eq where acceleration and continuous loss are in equilibrium if the particle's residence time in the system is sufficient at χ eq . In general, the impact of continuous and catastrophic momentum changes plays a crucial role in the shape of the steady-state momentum distribution of the accelerated particles, where simplified unbroken power-law approximations are often not adequate.}, archive = {J_ApJ}, author = {Dominik Walter and Björn Eichmann}, doi = {10.3847/1538-4357/adb1c2}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {22}, shortjournal = {The Astrophys. J.}, title = {Stochastic acceleration in weakly turbulent astrophysical environments}, volume = {981}, year = {2025}, }
• (2025). Tracing coherent gas structures in the central region of the starburst galaxy NGC 253. II. gas excitation and star formation. ApJ, 981(1), 21. (www)

  @article{ , abstract = {Molecular gas in the central region of the starburst galaxy NGC 253 is complicated because of the combination of different gas kinematics, including stellar feedback, noncircular motions, and magnetic activity. In paper I, we used the latest multitransition, multi-isotope CO-line data sets obtained with the Atacama Large Millimeter/submillimeter Array to classify the molecular gas within the central 850 pc in radius into 28 coherent structures, and we proposed a three-dimensional geometric structure for the gas in the central region of this galaxy. In this paper, we utilize intensity ratios between 12 CO ( J = 3–2), 12 CO ( J = 1–0), HCN ( J = 4–3), and SiO ( J = 2–1) to investigate the physical properties of each coherent structure, comparing the distributions with (proto-)star clusters, known as superbubble candidates, and stars. We found that the excitation state of the gas tends to increase toward the galactic center, and we identified high-excitation states in the gas with noncircular motions. From analyses of HCN ( J = 4–3) and SiO ( J = 2–1), we found that the dense, star-forming clumps that drive the starburst reside either at the points connecting any two streams or in the central region where two oppositely directed, accretion flows terminate. Based on analyses of the intensity ratios and the proposed geometric structure, we suggest that some superbubbles may instead be the overlap of the coherent structures rather than an expanding shell. From all these results, we propose a scenario in which the starburst was triggered by cloud–cloud collisions caused by interactions of streams and/or by magnetic flotation and/or efficient accretion along a stellar bar.}, archive = {J_ApJ}, author = {Ryotaro Konishi and R. Enokiya and Y. Fukui and K. Tachihara and K. Muraoka and T. Onishi}, doi = {10.3847/1538-4357/ad8c42}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {21}, shortjournal = {The Astrophys. J.}, title = {Tracing coherent gas structures in the central region of the starburst galaxy NGC 253. II. gas excitation and star formation}, volume = {981}, year = {2025}, }
• (2025). Dynamical and atmospheric characterization of the substellar companion HD 33632 ab from direct imaging, astrometry, and radial-velocity data*. ApJ, 981(1), 20. (www)

  @article{ , abstract = {We present follow-up SCExAO/CHARIS H- and K -band ( R ∼ 70) high-contrast integral field spectroscopy and Keck/NIRC2 photometry of directly imaged brown dwarf companion HD 33632 Ab and new radial-velocity data for the system from the SOPHIE spectrograph, complemented by Hipparcos and Gaia astrometry. These data enable more robust spectral characterization compared to lower-resolution spectra from the discovery paper and more than double the available astrometric and radial-velocity baseline. HD 33632 Ab's spectrum is well reproduced by a field L8.5–L9.5 dwarf. Using the Exo-REM atmosphere models, we derive a best-fit temperature, surface gravity, and radius of T eff = 1250 K, log( g ) = 5, and R = 0.97 R J , respectively, as well as a solar C/O ratio. Adding the SOPHIE radial-velocity data enables far tighter constraints on the companion's orbital properties (e.g., i = {47.5}_{-4.7}^{+2.5} o ) and dynamical mass ( {52.8}_{-2.4}^{+2.6} M J ) than derived from imaging data and Gaia eDR3 astrometry data alone. HD 33632 Ab should be a prime target for multiband imaging and spectroscopy with the James Webb Space Telescope and the Roman Space Telescope's Coronagraphic Instrument, shedding detailed light on HD 33632 Ab's clouds and chemistry and providing a key reference point for understanding young exoplanet atmospheres.}, archive = {J_ApJ}, author = {Mona El Morsy and Thayne Currie and Danielle Bovie and Masayuki Kuzuhara and Brianna Lacy and Yiting Li and Taylor Tobin and Timothy D. Brandt and Jeffrey Chilcote and Olivier Guyon and Tyler D. Groff and Julien Lozi and Sebastien Vievard and Vincent Deo and Nour Skaf and Francois Bouchy and Isabelle Boisse and Erica Dykes and N. Jeremy Kasdin and Motohide Tamura}, doi = {10.3847/1538-4357/ada3be}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {20}, shortjournal = {The Astrophys. J.}, title = {Dynamical and atmospheric characterization of the substellar companion HD 33632 ab from direct imaging, astrometry, and radial-velocity data*}, volume = {981}, year = {2025}, }
• (2025). Tip of the iceberg: Overmassive black holes at 4 < z < 7 found by JWST are not inconsistent with the local ${{ \mathcal m }}_{\mathrm{BH}}-{{ \mathcal m }}_{\star }$ relation. ApJ, 981(1), 19. (www)

  @article{ , abstract = {JWST is revealing a remarkable new population of high-redshift ( z ≳ 4), low-luminosity active galactic nuclei in deep surveys and detecting the host galaxy's stellar light in the most luminous and massive quasars at z ∼ 6 for the first time. Recent findings claim that supermassive black holes (SMBHs) in these systems are significantly more massive than predicted by the local black hole (BH) mass–stellar mass ( {{ \mathcal M }}_{\mathrm{BH}}-{{ \mathcal M }}_{\star } ) relation and that this is not due to sample selection effects. Through detailed statistical modeling, we demonstrate that the coupled effects of selection biases (i.e., finite detection limit and requirements for detecting broad lines) and measurement uncertainties can largely explain the reported offset and flattening in the observed {{ \mathcal M }}_{\mathrm{BH}}-{{ \mathcal M }}_{\star } relation toward the upper envelope of the local relation, even for those at {{ \mathcal M }}_{\mathrm{BH}}\,\lt 1{0}^{8}\,{M}_{\odot } . We further investigate the possible evolution of the {{ \mathcal M }}_{\mathrm{BH}}-{{ \mathcal M }}_{\star } relation at z ≳ 4 with careful treatment of observational biases and consideration of the degeneracy between intrinsic evolution and dispersion in this relation. The bias-corrected intrinsic {{ \mathcal M }}_{\mathrm{BH}}-{{ \mathcal M }}_{\star } relation in the low-mass regime ( {{ \mathcal M }}_{\star }\lesssim 1{0}^{10}\,{M}_{\odot } ) suggests a large population of low-mass BHs ( {{ \mathcal M }}_{\mathrm{BH}}\lesssim 1{0}^{5}\,{M}_{\odot } ), possibly originating from lighter seeds, may remain undetected or unidentified. These results underscore the importance of forward modeling observational biases to better understand BH seeding and SMBH–galaxy coevolution mechanisms in the early universe, even with the deepest JWST surveys.}, archive = {J_ApJ}, author = {Junyao Li and John D. Silverman and Yue Shen and Marta Volonteri and Knud Jahnke and Ming-Yang Zhuang and Matthew T. Scoggins and Xuheng Ding and Yuichi Harikane and Masafusa Onoue and Takumi S. Tanaka}, doi = {10.3847/1538-4357/ada603}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {19}, shortjournal = {The Astrophys. J.}, title = {Tip of the iceberg: Overmassive black holes at 4 < z < 7 found by JWST are not inconsistent with the local ${{ \mathcal m }}_{\mathrm{BH}}-{{ \mathcal m }}_{\star }$ relation}, volume = {981}, year = {2025}, }
• (2025). Boltzmann–Poisson theory of nonthermal self-gravitating gases, cold dark matter, and solar atmosphere. ApJ, 981(1), 18. (www)

  @article{ , abstract = {Space and astrophysical plasmas or gases can reach various states of thermal or nonthermal quasi-equilibrium, depending on the collisional age of the observed system. Widely observed in space plasmas, the Kappa (or \kappa —power-law) velocity distribution (KVD) is eloquent evidence of nonthermal states. M. P. Leubner has developed KVD models for luminous gases and cold dark matter (DM) with empirical density profiles described by \kappa > 0 and \kappa < 0, respectively. The predicted temperature profiles, however, are not in qualitative agreement with the nonmonotonic features expected in some gas and DM models. This study adopts the more consistent regularized Kappa distribution (RKD) to derive the equilibrium profiles of self-gravitating gas and DM halos within a Boltzmann–Poisson theoretical approach. The new RKD models can replicate better than the KVD models the Navarro–Frenk–White density profile of the DM near the basic halos and can also produce nonmonotonic temperature profiles. The same RKD formalism is also applied to non-self-gravitating astrophysical systems, which shows that for highly nonthermal cases ( \kappa \unicode{x0007E}1 < 3/2), the temperature of the surrounding gases decreases initially in a narrow region. The temperature then increases sharply and reaches a high saturated value, resembling the overheated solar atmosphere, while the density profile near the surface may depart from the observations. Compared to the KVD models, the new RKD models can provide improved descriptions of gravitational equilibrium systems, especially for highly nonthermal cases and temperature profiles.}, archive = {J_ApJ}, author = {L.-N. Hau and C.-K. Chang and M. Lazar and S. Poedts}, doi = {10.3847/1538-4357/ada76f}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {18}, shortjournal = {The Astrophys. J.}, title = {Boltzmann–Poisson theory of nonthermal self-gravitating gases, cold dark matter, and solar atmosphere}, volume = {981}, year = {2025}, }
• (2025). A new algorithm for detecting X-ray shots in cyg X-1. ApJ, 981(1), 17. (www)

  @article{ , abstract = {The short-term X-ray variability of Cyg X-1 can be interpreted as a random occurrence of mini-flares known as the shots, whose physical nature is still unclear. We propose a new algorithm for shot identification in the X-ray light curve, based on baseline detection and template fitting. Compared with previous techniques, our algorithm allows us to detect shots with lower amplitudes and shorter time separations. With NICER observations, we find that, after correction for detection sensitivity, both the shot amplitude and recurrence rate are positively scaled with the mean count rate, while the recurrence rate has a much higher dependence on the count rate. These suggest that a higher mass accretion rate will drive more and slightly larger shots. We also find that the abrupt hardening near the shot peak found in previous studies is attributed to different shot profiles in different energy bands; there is no need to involve a rapid physical process to suddenly harden the emitting spectrum.}, archive = {J_ApJ}, author = {Jin Qin and Hua Feng and Lian Tao}, doi = {10.3847/1538-4357/ada774}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {17}, shortjournal = {The Astrophys. J.}, title = {A new algorithm for detecting X-ray shots in cyg X-1}, volume = {981}, year = {2025}, }
• (2025). Mapping the outcomes of stellar evolution in the disks of active galactic nuclei. ApJ, 981(1), 16. (www)

  @article{ , abstract = {The disks of active galactic nuclei (AGNs) are expected to be populated by numerous stars, either formed in the outer regions of the disk via gravitational instability or captured from the nearby nuclear star cluster. Regardless of their formation mechanism, these stars experience altered evolutionary paths, mostly shaped by the accretion of dense disk material. In this study, through the comparison of different timescales, we chart the evolutionary outcomes of these AGN stars as a function of disk radius and across a range of supermassive black hole masses, spanning from 10 6 to 10 9 M ⊙ , for two popular AGN disk models. We find that in the outer regions of the disk, stars evolve similarly to those in the interstellar medium, but in the inner and denser regions, accretion quickly turns low-mass stars into massive stars, and their fate depends on just how quickly they accrete. If accretion occurs at a faster rate than nuclear burning, they can reach a quasi-steady "immortal" state. If stars accrete faster than they can thermally adjust, runaway accretion occurs, potentially preventing a quasi-steady state and altering the disk structure. During the AGN lifetime, in the regions of the disk that produce massive stars, supernovae (SNe) and gamma-ray bursts (GRBs) may occur within the disk over a wide range of optical depths and ambient densities. Subsequently, in the final phase of the AGN, as the disk becomes depleted, formerly immortal stars will be unable to replenish their fuel, leading to additional SNe and GRBs.}, archive = {J_ApJ}, author = {Gaia Fabj and Alexander J. Dittmann and Matteo Cantiello and Rosalba Perna and Johan Samsing}, doi = {10.3847/1538-4357/ada896}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {16}, shortjournal = {The Astrophys. J.}, title = {Mapping the outcomes of stellar evolution in the disks of active galactic nuclei}, volume = {981}, year = {2025}, }
• (2025). A measurement of atmospheric circular polarization with POLARBEAR. ApJ, 981(1), 15. (www)

  @article{ , abstract = {At millimeter wavelengths, the atmospheric emission is circularly polarized owing to the Zeeman splitting of molecular oxygen by the Earth's magnetic field. We report a measurement of the signal in the 150 GHz band using 3 yr of observational data with the Polarbear project. Nonidealities of a continuously rotating half-wave plate (HWP) partially convert circularly polarized light to linearly polarized light. While Polarbear detectors are sensitive to linear polarization, this effect makes them sensitive to circular polarization. Although this was not the intended use, we utilized this conversion to measure circular polarization. We reconstruct the azimuthal gradient of the circular polarization signal and measure its dependency from the scanning direction and the detector bandpass. We compare the signal with a simulation based on atmospheric emission theory, the detector bandpass, and the HWP leakage spectrum model. We find the ratio of the observed azimuthal slope to the simulated slope is 0.92 ± 0.01(stat) ± 0.07(sys). This ratio corresponds to a brightness temperature of 3.8 mK at the effective band center of 121.8 GHz and bandwidth of 3.5 GHz estimated from representative detector bandpass and the spectrum of Zeeman emission. This result validates our understanding of the instrument and reinforces the feasibility of measuring the circular polarization using the imperfection of continuously rotating HWP. Continuously rotating HWP is popular in ongoing and future cosmic microwave background experiments to modulate the polarized signal. This work shows a method for signal extraction and leakage subtraction that can help measure circular polarization in such experiments.}, archive = {J_ApJ}, author = {Takuro Fujino and Satoru Takakura and Shahed Shayan Arani and Darcy Barron and Carlo Baccigalupi and Yuji Chinone and Josquin Errard and Giulio Fabbian and Chang Feng and Nils W. Halverson and Masaya Hasegawa and Masashi Hazumi and Oliver Jeong and Daisuke Kaneko and Brian Keating and Akito Kusaka and Adrian Lee and Tomotake Matsumura and Lucio Piccirillo and Christian L. Reichardt and Kana Sakaguri and Praween Siritanasak and Kyohei Yamada}, doi = {10.3847/1538-4357/ada89b}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {15}, shortjournal = {The Astrophys. J.}, title = {A measurement of atmospheric circular polarization with POLARBEAR}, volume = {981}, year = {2025}, }
• (2025). Prompt gamma-ray burst recognition through waterfalls and deep learning. ApJ, 981(1), 14. (www)

  @article{ , abstract = {Gamma-ray bursts (GRBs) are one of the most energetic phenomena in the cosmos, whose study can probe physics extremes beyond the reach of laboratories on Earth. Our quest to unravel the origin of these events and understand their underlying physics is far from complete. Central to this pursuit is the rapid classification of GRBs to guide follow-up observations and analysis across the electromagnetic spectrum and beyond. Here, we introduce a compelling approach that can set a milestone toward a new and robust GRB prompt classification method. Leveraging self-supervised deep learning, we pioneer a previously unexplored data product to approach this task: GRB waterfalls .}, archive = {J_ApJ}, author = {Michela Negro and Nicoló Cibrario and Eric Burns and Joshua Wood and Adam Goldstein and Tito Dal Canton}, doi = {10.3847/1538-4357/ada8a9}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {14}, shortjournal = {The Astrophys. J.}, title = {Prompt gamma-ray burst recognition through waterfalls and deep learning}, volume = {981}, year = {2025}, }
• (2025). Impact of teleparallelism on addressing current tensions and exploring the GW cosmology. ApJ, 981(1), 13. (www)

  @article{ , abstract = {The H 0 and S 8 tensions highlight critical discrepancies in modern cosmology, challenging the standard Lambda cold dark matter model. The H 0 tension arises from conflicting measurements between local probes and early-Universe predictions. Similarly, the S 8 tension, related to the amplitude of matter clustering, exposes inconsistencies between cosmic microwave background data and weak gravitational lensing surveys. The primary goal of this work is to address these tensions by modifying the underlying geometric framework. Specifically, we test two f ( T ) gravity models using cosmic chronometers, baryonic acoustic oscillations, gamma-ray bursts, and Pantheon+SH0ES data sets and compare the results with gravitational-wave data for validation. Both teleparallel models demonstrate promising performance in simultaneously alleviating the H 0 and S 8 tensions.}, archive = {J_ApJ}, author = {Sai Swagat Mishra and N. S. Kavya and P. K. Sahoo and V. Venkatesha}, doi = {10.3847/1538-4357/adabc6}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {13}, shortjournal = {The Astrophys. J.}, title = {Impact of teleparallelism on addressing current tensions and exploring the GW cosmology}, volume = {981}, year = {2025}, }
• (2025). Early grain growth in the young protostellar disk HH 212 supported by dust self-scattering modeling. ApJ, 981(1), 12. (www)

  @article{ , abstract = {Grain growth in disks around young stars plays a crucial role in the formation of planets. Early grain growth has been suggested in the HH 212 protostellar disk by previous polarization observations. To confirm it and to determine the grain size, we analyze high-resolution multiband observations of the disk obtained with the Atacama Large Millimeter/submillimeter Array (ALMA) in bands 9 (0.4 mm), 7 (0.9 mm), 6 (1.3 mm), and 3 (3 mm), as well as with the Very Large Array (VLA) in band Ka (9 mm), and we present new VLA data in bands Q (7 mm), K (1.3 cm), and X (3 cm). We adopt a parameterized flared disk model to fit the continuum maps of the disk in these bands and derive the opacities, albedos, and opacity spectral index β of the dust in the disk, taking into account the dust scattering ignored in the previous work modeling the multiband data of this source. For the VLA bands, we only include the band Q data in our modeling to avoid free–free emission contamination. The obtained opacities, albedos, and opacity spectral index β (with a value of  ∼1.2) suggest that the upper limit of maximum grain size in the disk should be  ∼130 μ m, consistent with that implied in the previous polarization observations in band 7, supporting the grain growth in this disk. The values of the absorption opacities further highlight the need for a new dust composition model for Class 0/I disks.}, archive = {J_ApJ}, author = {Ying-Chi Hu and Chin-Fei Lee and Zhe-Yu Daniel Lin and Zhi-Yun Li and John J. Tobin and Shih-Ping Lai}, doi = {10.3847/1538-4357/adabe1}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {12}, shortjournal = {The Astrophys. J.}, title = {Early grain growth in the young protostellar disk HH 212 supported by dust self-scattering modeling}, volume = {981}, year = {2025}, }
• (2025). Solar gamma-ray evidence for a distinct population of >1 MeV flare-accelerated electrons. ApJ, 981(1), 11. (www)

  @article{ , abstract = {Significant improvements in our understanding of nuclear γ -ray line production and instrument performance allow us to better characterize the continuum emission from electrons at energies ≳300 keV during solar flares. We represent this emission by the sum of a power-law (PL) extension of hard X-rays and a power law times an exponential function (PLexp). We fit the γ -ray spectra in 25 large flares observed over 40 yr with this continuum and the calculated spectra of all known nuclear components. The PLexp is separated spectroscopically from the other components, and its presence is required with >99% confidence in 18 of the flares. Its distinct origin is suggested by significant differences between its time histories and those of the PL and nuclear components in 18 of the flares. RHESSI imaging/spectroscopy of the 2005 January 20 flare reveals that the PL and nuclear components come from the footpoints, while the PLexp component comes from the corona. While the index and flux of the anisotropic PL component are dependent on the flare's heliocentric angle, the PLexp parameters do not show comparable dependences with 99.5% confidence. The PLexp spectrum is flat at low energies and rolls over at a few megaelectronvolts (MeV). Such a shape can be produced by thin-target bremsstrahlung from electrons with a spectrum that peaks between 3 and 5 MeV and by inverse Compton scattering of soft X-rays by 10–20 MeV electrons, or by a combination of the two. These electrons can produce radiation detectable at other wavelengths.}, archive = {J_ApJ}, author = {Gerald H. Share and Ronald J. Murphy and Brian R. Dennis and Justin D. Finke}, doi = {10.3847/1538-4357/adac60}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {11}, shortjournal = {The Astrophys. J.}, title = {Solar gamma-ray evidence for a distinct population of >1 MeV flare-accelerated electrons}, volume = {981}, year = {2025}, }
• (2025). Modulation of X-ray flux by obscuration of neutron star boundary layer. ApJ, 981(1), 10. (www)

  @article{ , abstract = {The quasiperiodic oscillations (QPOs) observed in the X-ray variability of both black hole (BH) and neutron star (NS) systems provide a tool for probing strong gravity and dense matter equations of state. Nevertheless, the mechanism of QPO modulation in NS systems, where the amplitudes of QPOs with frequencies approaching the kHz range are very high in comparison to BH high-frequency QPOs, remains an unsolved puzzle. Relativistic ray tracing of photons emitted from the immediate vicinity of compact objects has, to date, been used to investigate various mechanisms that explain the observed weak BH QPOs. However, it has not been applied to model the NS QPO signal, which requires incorporating the NS surface and a bright boundary layer (BL) on it. Here, we explore the QPO modulation mechanisms based on the BL obscuration. Using simplified models of axisymmetric oscillations of thick accretion disks (tori), we demonstrate that the disk oscillations drive the high NS QPO amplitudes through BL obscuration, which is relevant, especially for vertical oscillations. We also demonstrate that obscuration effects enable the observability of the Keplerian frequency in the case of disks that decay due to instabilities.}, archive = {J_ApJ}, author = {G. Török and K. Klimovičová and D. Lančová and M. Matuszková and E. Šrámková and M. Urbanec and M. Čemeljić and R. Šprňa and V. Karas}, doi = {10.3847/1538-4357/adad71}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {10}, shortjournal = {The Astrophys. J.}, title = {Modulation of X-ray flux by obscuration of neutron star boundary layer}, volume = {981}, year = {2025}, }
• (2025). Probing cosmology with 92 localized fast radio bursts and DESI BAO. ApJ, 981(1), 9. (www)

  @article{ , abstract = {Recent baryon acoustic oscillation (BAO) measurements from the Dark Energy Spectroscopic Instrument (DESI) collaboration, combined with the cosmic microwave background (CMB) and type Ia supernovae observations, suggest a preference for dynamical dark energy (DDE) with w 0 > −1 and w a < 0. Given the cosmological origin of fast radio bursts (FRBs), the combination of their dispersion measures (DMs) and host galaxy redshifts makes localized FRBs a valuable tool for probing cosmology. Using an updated sample of 92 localized FRBs, along with DESI BAO, PlantheonPlus, and CMB data, we constrain the dark energy (DE) equation of state (EoS) under the Chevallier–Polarski–Linder parameterization. We find that even without incorporating CMB data, DDE remains preferred with {w}_{0}=-0.85{5}_{-0.084}^{+0.084} and {w}_{a}=-1.17{4}_{-0.491}^{+0.462} at a confidence level of  ∼2.5 σ . A joint analysis constrains these to be {w}_{0}=-0.78{4}_{-0.064}^{+0.064} and {w}_{a}=-0.87{2}_{-0.278}^{+0.269} , showing a discrepancy with ΛCDM at a  ∼3.1 σ level. Furthermore, using localized FRBs alone, we estimate the Hubble constant H 0 to be 69.0{4}_{-2.07}^{+2.30} and 75.6{1}_{-2.07}^{+2.23}\,{\rm{km}}\,{{\rm{s}}}^{-1}\,{{\rm{Mpc}}}^{-1} , assuming the Galactic electron density models to be NE2001 and YMW16, respectively. Thus, accurate accounting of the Galactic DM is crucial for resolving the Hubble tension with FRBs. Future BAO measurements, next-generation CMB experiments, and more localized FRBs will further constrain the DE EoS and the cosmological parameters.}, archive = {J_ApJ}, author = {Yi-Ying Wang and Shi-Jie Gao and Yi-Zhong Fan}, doi = {10.3847/1538-4357/adade8}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {9}, shortjournal = {The Astrophys. J.}, title = {Probing cosmology with 92 localized fast radio bursts and DESI BAO}, volume = {981}, year = {2025}, }
• (2025). Radial dependence of ion fluences in the 2023 july 17 solar energetic particle event from parker solar probe to STEREO and ACE. ApJ, 981(1), 8. (www)

  @article{ , abstract = {In the latter moments of 2023 July 17, the solar active region (AR) 13363, near the southwestern face of the Sun, was undergoing considerable evolution, which resulted in a significant solar energetic particle (SEP) event measured by Parker Solar Probe's Integrated Science Investigation of the Sun (IS⊙IS) and near-Earth spacecraft. Remote observations from GOES and CHASE captured two M5.0+ solar flares that peaked at 23:34 and 00:06 UT from the source region. In tandem, STEREO COR2 first recorded a small, narrow coronal mass ejection (CME) emerging at 22:54 UT and then saw a major halo CME emerge at 23:43 UT with a bright, rapidly expanding core and CME-driven magnetic shock with an estimated speed of ∼1400 km s −1 . Parker Solar Probe was positioned at 0.65 au, near-perfectly on the nominal Parker spiral magnetic field line, which connected Earth and the AR for a 537 km s −1 ambient solar wind speed at L1. This fortuitous alignment provided the opportunity to examine how the SEP velocity dispersion, energy spectra, elemental composition, and fluence varied from 0.65 to 1 au along a shared magnetic connection to the Sun. We find a strong radial gradient, which is best characterized for H and He as r −4.0 , and most surprisingly, is stronger for O and Fe, which is better described by r −5.7 .}, archive = {J_ApJ}, author = {G. D. Muro and C. M. S. Cohen and Z. Xu and R. A. Leske and E. R. Christian and A. C. Cummings and G. De Nolfo and M. I. Desai and F. Fraschetti and J. Giacalone and A. Labrador and D. J. McComas and J. G. Mitchell and D. G. Mitchell and J. Rankin and N. A. Schwadron and M. Shen and M. E. Wiedenbeck and S. D. Bale and O. Romeo and A. Vourlidas}, doi = {10.3847/1538-4357/adadf7}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {8}, shortjournal = {The Astrophys. J.}, title = {Radial dependence of ion fluences in the 2023 july 17 solar energetic particle event from parker solar probe to STEREO and ACE}, volume = {981}, year = {2025}, }
• (2025). Multiband nonthermal radiative properties of the pulsar wind nebula CTB 87. ApJ, 981(1), 7. (www)

  @article{ , abstract = {The pulsar wind nebula CTB 87 (G74.9+1.2) is one of the sources emitting γ -rays with energies higher than 10 TeV, as measured by the Very Energetic Radiation Imaging Telescope Array System telescope. In this study, we undertake a reanalysis of the GeV emission from the CTB 87 region, utilizing ∼16 yr of high-energy γ -ray data collected with the Fermi Large Area Telescope. In the energy range of 0.03–1 TeV, the spectrum can be adequately described by a power-law model with an index of 1.34 ± 0.18, and the integral energy flux is calculated to be (7.25 ± 1.36) × 10 −13 erg cm −2 s −1 . Based on the multiband data, we have employed a time-dependent model to investigate the nonthermal emission properties of CTB 87. In the model, it is assumed that particles with broken power-law energy distributions are continuously injected into the nebula. This results in multiband nonthermal emission being produced by relativistic leptons via synchrotron radiation and inverse Compton processes. Furthermore, the model suggests an energy of approximately 2.4 PeV for the most energetic particle in the nebula.}, archive = {J_ApJ}, author = {Yunlu Gong and Liancheng Zhou and Qi Xia and Haiyun Zhang and Jun Fang and Li Zhang}, doi = {10.3847/1538-4357/adae90}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {7}, shortjournal = {The Astrophys. J.}, title = {Multiband nonthermal radiative properties of the pulsar wind nebula CTB 87}, volume = {981}, year = {2025}, }
• (2025). Torsional alfvén shock waves in stratified coronal loops. ApJ, 981(1), 6. (www)

  @article{ , abstract = {The evolution of weakly nonlinear Alfvén waves in coronal loops in the density structuring both across and along the field while experiencing dissipation is highlighted. Energy transfer due to shock formation in coronal loops provides the basis for the context of the present study. Coronal loops are modeled analytically using the magnetohydrodynamic (MHD) theory in cylindrical geometry, incorporating stratification and viscosity. The effects of the external medium, along with equilibrium conditions, are considered, with the background magnetic field aligned parallel to the loop axis. The second-order thin flux tube approximation is employed to derive a Cohen–Kulsrud–Burgers type of evolutionary equation that highlights the influences of nonlinear, dissipative, and stratification terms, alongside the effect of the external medium. The Alfvén wave speed in coronal loops reaches its maximum when shocks are experienced. If not due to low amplitudes, the maximum is observed at the other footpoint. The location of shock formation is determined by the ratio of the Alfvén wave amplitude and the background Alfvén wave speed. The existence of energy transfer mechanisms due to MHD shocks at various locations of coronal loops, especially loop footpoints, brings to mind that observed energy transfers in the case of coronal loops or a set of loops not only provide coronal heating but also provide transition region heating subject to conditions. For high plasma- β values at lower altitudes, shock formation is less dependent on the external medium and depends strongly on the loop's internal dynamics. This is contrary to open magnetic structures.}, archive = {J_ApJ}, author = {S. M. Hejazi and S. Vasheghani Farahani and K. Hajisharifi}, doi = {10.3847/1538-4357/adaeab}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {6}, shortjournal = {The Astrophys. J.}, title = {Torsional alfvén shock waves in stratified coronal loops}, volume = {981}, year = {2025}, }
• (2025). Automatic machine learning framework to study morphological parameters of AGN host galaxies within z < 1.4 in the hyper supreme-cam wide survey. ApJ, 981(1), 5. (www)

  @article{ , abstract = {We present a composite machine learning framework to estimate posterior probability distributions of bulge-to-total light ratio, half-light radius, and flux for active galactic nucleus (AGN) host galaxies within z < 1.4 and m < 23 in the Hyper Supreme-Cam (HSC) Wide survey. We divide the data into five redshift bins: low (0 < z < 0.25), mid (0.25 < z < 0.5), high (0.5 < z < 0.9), extra (0.9 < z < 1.1), and extreme (1.1 < z < 1.4), and train our models independently in each bin. We use PSFGAN to decompose the AGN point-source light from its host galaxy, and invoke the Galaxy Morphology Posterior Estimation Network (GaMPEN) to estimate morphological parameters of the recovered host galaxy. We first trained our models on simulated data, and then fine-tuned our algorithm via transfer learning using labeled real data. To create training labels for transfer learning, we used GALFIT to fit  ∼20,000 real HSC galaxies in each redshift bin. We comprehensively examined that the predicted values from our final models agree well with the GALFIT values for the vast majority of cases. Our PSFGAN + GaMPEN framework runs at least three orders of magnitude faster than traditional light-profile fitting methods, and can be easily retrained for other morphological parameters or on other data sets with diverse ranges of resolutions, seeing conditions, and signal-to-noise ratios, making it an ideal tool for analyzing AGN host galaxies from large surveys coming soon from the Rubin-LSST, Euclid, and Roman telescopes.}, archive = {J_ApJ}, author = {Chuan Tian and C. Megan Urry and Aritra Ghosh and Daisuke Nagai and Tonima T. Ananna and Meredith C. Powell and Connor Auge and Aayush Mishra and David B. Sanders and Nico Cappelluti and Kevin Schawinski}, doi = {10.3847/1538-4357/adaec0}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {5}, shortjournal = {The Astrophys. J.}, title = {Automatic machine learning framework to study morphological parameters of AGN host galaxies within z < 1.4 in the hyper supreme-cam wide survey}, volume = {981}, year = {2025}, }
• (2025). The influence of chromospheric activity on line formation. ApJ, 981(1), 4. (www)

  @article{ , abstract = {One of the primary sources of stellar spectral variability is magnetic activity. While our current understanding of chromospheric activity is largely derived from specific lines sensitive to chromospheric heating, such as the Ca ii H and K doublet, previous observational studies have shown that other spectral lines are also affected. To investigate the influence of activity on line formation in greater detail, we constructed a set of stellar models for hypothetical G2 dwarf stars with varying levels of activity and calculated their synthetic spectra. A comparison of these spectra revealed two spectral regions most significantly impacted by activity: approximately 3300–4400 Å and 5250–5500 Å. By calculating the total contribution function of the lines, we determined that the emergence of a secondary chromospheric contribution to line formation is the primary mechanism driving these changes. Based on our calculations and analysis, we compiled a list of transition lines and their corresponding changes due to chromospheric activity. This list could serve as a valuable tool for selecting spectral lines applicable to a wide range of astrophysical studies.}, archive = {J_ApJ}, author = {Mariela C. Vieytes and Lily L. Zhao and Megan Bedell}, doi = {10.3847/1538-4357/adb0c6}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {4}, shortjournal = {The Astrophys. J.}, title = {The influence of chromospheric activity on line formation}, volume = {981}, year = {2025}, }
• (2025). Climate transition to temperate nightside at high atmosphere mass. ApJ, 981(1), 3. (www)

  @article{ , abstract = {Our recent work shows how M-Earth climates and transmission spectra depend on the amount of ice-free ocean on the planet's dayside and the mass of N 2 in its atmosphere. M-Earths with more ice-free ocean and thicker atmospheres are hotter and more humid and have larger water vapor features in their transmission spectra. In this paper, we describe a climate transition in high- p N 2 simulations from the traditional "eyeball" M-Earth climate, in which only the substellar region is temperate, to a "temperate nightside" regime, in which both the dayside and the nightside are entirely ice-free. Between these two states, there is a "transition" regime with partial nightside ice cover. We use 3D climate simulations to describe the climate transition from frozen to deglaciated nightsides. We attribute this transition to increased advection and heat transport by water vapor in thicker atmospheres. We find that the nightside transitions smoothly back and forth between frozen and ice-free when the instellation or p CO 2 is perturbed, with no hysteresis. We also find an analogous transition in colder planets: those with thin atmospheres can have a dayside hot spot when the instellation is low, whereas those with more massive atmospheres are more likely to be in the "snowball" regime, featuring a completely frozen dayside, due to the increased advection of heat away from the substellar point. We show how both of these climate transitions are sensitive to instellation, land cover, and atmosphere mass. We generate synthetic transmission spectra and phase curves for the range of climates in our simulations.}, archive = {J_ApJ}, author = {Evelyn Macdonald and Kristen Menou and Christopher Lee and Adiv Paradise}, doi = {10.3847/1538-4357/adb0cb}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {3}, shortjournal = {The Astrophys. J.}, title = {Climate transition to temperate nightside at high atmosphere mass}, volume = {981}, year = {2025}, }
• (2025). High significance detection of the dark substructure in gravitational lens SDSS j0946+1006 by image pixel supersampling. ApJ, 981(1), 2. (www)

  @article{ , abstract = {Recent studies have shown that the dark substructure reported in the gravitational lens SDSS J0946+1006 has a high central density, which is in apparent tension with the flat cold dark matter (ΛCDM) paradigm. However, its detection significance has been found in D. J. Ballard et al. to be sensitive to prior assumptions about the smoothness of the source galaxy. Here we show that the detection significance of the substructure is higher than previously reported (log-Bayes factor {\rm{\Delta }}\mathrm{ln}\,{ \mathcal E }\approx 143 , equivalent to a ∼17 σ detection) by approximating the integration of light over each pixel via ray tracing and averaging over many subpixels—a technique known as supersampling—and this result is insensitive to the assumed prior on the source galaxy smoothness. Assuming a dark matter subhalo, the combination of supersampling and modeling both sets of lensed arcs also tightens the subhalo constraints: we find the subhalo's projected mass within 1 kpc lies in the range (2.2–3.4) × 10 9 M ⊙ at 95% confidence in our highest evidence model, while the log-slope of the subhalo's projected density at 1 kpc is steeper than −1.75 at the 95% confidence level, further establishing it as an outlier compared to expectations from CDM. We also identify a systematic that has biased the slope of the primary lensing galaxy's density profile in prior studies, which we speculate might be due to the presence of dust or an imperfect foreground subtraction. Our analysis places the existence of the substructure on firmer ground, and should motivate deeper follow-up observations to better constrain its properties and clarify its apparent tension with ΛCDM.}, archive = {J_ApJ}, author = {Quinn E. Minor}, doi = {10.3847/1538-4357/adb1b6}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {2}, shortjournal = {The Astrophys. J.}, title = {High significance detection of the dark substructure in gravitational lens SDSS j0946+1006 by image pixel supersampling}, volume = {981}, year = {2025}, }
• (2025). Coupling of dynamical tide and orbital motion. ApJ, 981(1), 1. (www)

  @article{ , abstract = {The dynamical tide consists of various waves that can resonate with orbital motion. We test this coupling of the dynamical tide and orbital motion using a simple 2D shallow water model, which can be applied to a rocky planet covered with a thin ocean or atmosphere. Then we take the Earth–Moon system as a fiducial model to calculate the tidal resonances and orbital evolution. We find that tidal dissipation can even increase with increasing orbital separation because of the coupling of the dynamical tide and orbital motion. We draw the conclusion that the coupling is not negligible to study the orbital evolution on a secular timescale.}, archive = {J_ApJ}, author = {Xing Wei}, doi = {10.3847/1538-4357/adb1e5}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {1}, shortjournal = {The Astrophys. J.}, title = {Coupling of dynamical tide and orbital motion}, volume = {981}, year = {2025}, }
• (2025). ALMA 0.1 pc view of molecular clouds associated with high-mass protostellar systems in the small magellanic cloud: Are low-metallicity clouds filamentary or not?. ApJ, 980(2), 269. (www)

  @article{ , abstract = {Filamentary molecular clouds are an essential intermediate stage in the star formation process. To test whether these structures are universal throughout cosmic star formation history, it is crucial to study low-metallicity environments within the Local Group. We present an analysis of Atacama Large Millimeter/submillimeter Array (ALMA) archival data at the spatial resolution of  ~0.1 pc for 17 massive young stellar objects (YSOs) in the Small Magellanic Cloud (SMC; Z ~ 0.2 Z ⊙ ). This sample represents approximately 30% of the YSOs confirmed by Spitzer spectroscopy. Early ALMA studies of the SMC have shown that the CO emission line traces an H 2 number density of  ≳10 4 cm −3 , an order of magnitude higher than in typical Galactic environments. Using the CO( J = 3–2) data, we investigate the spatial and velocity distribution of molecular clouds. Our analysis shows that about 60% of the clouds have steep radial profiles from the spine of the elongated structures, while the remaining clouds have a smooth distribution and are characterized by lower brightness temperatures. We categorize the former as filaments and the latter as nonfilaments. Some of the filamentary clouds are associated with YSOs with outflows and exhibit higher temperatures, likely reflecting their formation conditions, suggesting that these clouds are younger than the nonfilamentary ones. This indicates that even if filaments form during star formation, their steep structures may become less prominent and transition to a lower-temperature state. Such transitions in structure and temperature have not been reported in metal-rich regions, highlighting a key behavior for characterizing the evolution of the interstellar medium and star formation in low-metallicity environments.}, archive = {J_ApJ}, author = {Kazuki Tokuda and Yuri Kunitoshi and Sarolta Zahorecz and Kei E. I. Tanaka and Itsuki Murakoso and Naoto Harada and Masato I. N. Kobayashi and Tsuyoshi Inoue and Marta Sewiło and Ayu Konishi and Takashi Shimonishi and Yichen Zhang and Yasuo Fukui and Akiko Kawamura and Toshikazu Onishi and Masahiro N. Machida}, doi = {10.3847/1538-4357/ada5f8}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {269}, shortjournal = {The Astrophys. J.}, title = {ALMA 0.1 pc view of molecular clouds associated with high-mass protostellar systems in the small magellanic cloud: Are low-metallicity clouds filamentary or not?}, volume = {980}, year = {2025}, }
• (2025). LEIA discovery of the longest-lasting and most energetic stellar X-ray flare ever detected. ApJ, 980(2), 268. (www)

  @article{ , abstract = {The Lobster Eye Imager for Astronomy (LEIA) detected a new X-ray transient on 2022 November 7, identified as a superflare event occurring on a nearby K-type giant star HD 251108. The flux increase was also detected in follow-up observations at X-ray, UV, and optical wavelengths. The flare lasted for about 40 days in soft X-ray observations, reaching a peak luminosity of ∼1.1 × 10 34 erg s −1 in 0.5–4.0 keV, which is roughly 60 times the quiescent luminosity. Optical brightening was observed for only one night. The X-ray light curve is well described by a double fast rise and exponential decay model, attributed to the cooling process of a loop arcade structure formed subsequent to the initial large loop with a half-length of ∼1.9 × 10 12 cm. Time-resolved X-ray spectra were fitted by a four-temperature apec model (with three components being the quiescent background), showing significant evolution of plasma temperature and emission measure over time. The estimated energy released in the LEIA band is ∼3 × 10 39 erg, suggesting that this is likely the most energetic X-ray stellar flare with the longest duration detected to date.}, archive = {J_ApJ}, author = {Xuan Mao and He-Yang Liu and Song Wang and Zhixing Ling and Weimin Yuan and Huaqing Cheng and Haiwu Pan and Dongyue Li and Fabio Favata and Tuo Ji and Jujia Zhang and Xinlin Zhao and Jing Wang and Mingjun Liu and Yuan Liu and Zhiming Cai and Alberto J. Castro-Tirado and Yanfeng Dai and Licai Deng and Xu Ding and Kaifan Ji and Chichuan Jin and Yajuan Lei and Huali Li and Jun Lin and Huaqiu Liu and Shuai Liu and Hui Sun and Shengli Sun and Xiaojin Sun and Jianrong Shi and Jianguo Wang and Jingxiu Wang and Wenxin Wang and Jianyan Wei and Liping Xin and Dingrong Xiong and Chen Zhang and Wenda Zhang and Yonghe Zhang and Xiaofeng Zhang and Donghua Zhao and Guiping Zhou}, doi = {10.3847/1538-4357/ada698}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {268}, shortjournal = {The Astrophys. J.}, title = {LEIA discovery of the longest-lasting and most energetic stellar X-ray flare ever detected}, volume = {980}, year = {2025}, }
• (2025). Comparison of global h i and hα line profiles in MaNGA galaxy pairs with FAST. ApJ, 980(2), 267. (www)

  @article{ , abstract = {We present case studies comparing the global H i and H α emission line profiles of six galaxy pairs. The six pairs are selected to have different nuclear activities, with two hosting an active galactic nucleus, and in different merging stages—two of each from the premerging, merging, and postmerging stages. We observe their global H i spectra with the Five-hundred-meter Aperture Spherical radio Telescope, achieving a noise level of ~0.5 mJy. Five out of the six pair systems have secure detections of H i emissions (signal-to-noise ratio > 10). The H i fraction and star formation efficiency of the six pairs do not deviate from isolated galaxies. For the H i line profiles, common unique asymmetry is observed, indicating disturbances of the atomic gas from the galaxy interaction. The global H α spectra of the merger systems are constructed from the optical integral field spectroscopic observations by integrating the flux in corresponding line-of-sight velocity bins. The H α spectra tend to show multiple components in the premerger phase and single-component line profiles in the postmerger systems, while all H i spectra show single-component line profiles regardless of merger stages. The H i and H α spectra show offsets in the central velocities, which appear to decrease from >100 km s −1 in the premerger pair to <10 km s −1 in the postmergers. This trend is consistent with the scenario that, despite the significantly different distributions and kinematics of the atomic and ionized gases, the merging process may contribute to the mixing and eventually align various gas contents.}, archive = {J_ApJ}, author = {Gaoxiang Jin and Y. Sophia Dai and Cheng Cheng and Cong Kevin Xu and Jia-Sheng Huang and Lihwai Lin}, doi = {10.3847/1538-4357/ada935}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {267}, shortjournal = {The Astrophys. J.}, title = {Comparison of global h i and hα line profiles in MaNGA galaxy pairs with FAST}, volume = {980}, year = {2025}, }
• (2025). Fractality of magnetic helicity distribution in the solar corona. ApJ, 980(2), 266. (www)

  @article{ , abstract = {We find a universal power-law scaling of magnetic helicity distribution in the solar corona. Magnetic helicity is a dynamical invariant for ideal magnetohydrodynamics (MHD) and characterizes complex magnetic field structure by measuring the degree of knottiness of its field lines. We treat turbulent solar magnetic field as a superposition of random waves and develop a statistical topology method regarding the randomly tangled field lines. Based on the statistical behavior of the field lines, we consider their topology-specified structure and theoretically derive power laws for the distribution of magnetic flux and helicity. We find a power law of  −7/4 to the magnetic helicity distribution when the field line topology is equivalent to handle and  −5/4 when the field line topology is local open curve. We verify the universality of this new magnetic helicity fractality by observation to a number of 185 sunspots in newly emerging active regions during the 23rd and 24th solar cycle. This new distribution law reveals the fractal structure of the solar magnetic field.}, archive = {J_ApJ}, author = {Anda Xiong and Shangbin Yang and Quan Wang and Xin Liu}, doi = {10.3847/1538-4357/adaaed}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {266}, shortjournal = {The Astrophys. J.}, title = {Fractality of magnetic helicity distribution in the solar corona}, volume = {980}, year = {2025}, }
• (2025). High lithium abundance connection with the chromospheric helium in red giants: Spectroscopic and asteroseismic analyses. ApJ, 980(2), 265. (www)

  @article{ , abstract = {We present a study of correlations between high Li abundances and strong chromospheric He i λ 10830 absorption-line strengths in Kepler field giant stars. Our sample includes 84 giants with detectable solar-like oscillations in their light curves, and their Li abundances come from the literature or are measured here using LAMOST medium-resolution spectra. Evolutionary phases are determined through asteroseismic analysis, with mixed-mode period spacing (Δ P ) used to infer the time evolution of red clump (RC) giants. Near-IR observations of the He i λ 10830 line were obtained with the high-resolution Habitable-zone Planet Finder spectrograph on the Hobby–Eberly Telescope. We find high Li abundances and strong He i lines exclusively among RC giants, with their absence in red giant branch stars suggesting a shared origin linked to the He flash. Additionally, a steady decline in He i strength with decreasing Li abundance among RC giants indicates a correlation between these properties. Older, Li-normal RC giants are He weak, while most younger, super-Li-rich giants are He strong, suggesting temporal evolution of both phenomena. We hypothesize that the core He flash and subsequent subflashes may enhance Li abundances in RC giant photospheres and trigger heightened chromospheric activity, leading to stronger He i λ 10830 lines in younger RCs. Over time, following He flash, chromospheric activity diminishes, resulting in weaker He i lines in older, Li-normal RCs.}, archive = {J_ApJ}, author = {Anohita Mallick and Christopher Sneden and Bacham E. Reddy and Melike Afşar}, doi = {10.3847/1538-4357/adab78}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {265}, shortjournal = {The Astrophys. J.}, title = {High lithium abundance connection with the chromospheric helium in red giants: Spectroscopic and asteroseismic analyses}, volume = {980}, year = {2025}, }
• (2025). MUSEQuBES: The kinematics of o vi-bearing gas in and around low-redshift galaxies. ApJ, 980(2), 264. (www)

  @article{ , abstract = {We present a detailed study of the kinematics of O vi -bearing gas around 60 low-mass (median {\mathrm{log}}_{10}({M}_{\star }/{M}_{\odot }) = 8.9) galaxies at low redshift (0.1 < z < 0.7) using background quasars (median impact parameter  ≈115 kpc) as part of the MUSE Quasar-fields Blind Emitters Survey (MUSEQuBES). We find that the majority of the O vi absorbers detected within the virial radius have line-of-sight velocities smaller than the escape velocities and are thus consistent with being gravitationally bound, irrespective of the halo mass. However, the fraction of such absorbers declines at larger impact parameters. The Doppler b parameter and the velocity width (Δ v 90 ) of the O vi absorbers exhibit large scatter inside the virial radius of the host galaxies, but the scatter declines sharply at impact parameter D ≳ 2 R vir . For high-mass galaxies ( {\mathrm{log}}_{10}({M}_{\star }/{M}_{\odot }) >  9), O vi absorption displays a larger kinematic spread, quantified by the pixel-velocity two-point correlation function (TPCF). However, the difference becomes marginal when the pixel velocities are scaled by the galaxies' circular velocities. We do not find any significant difference between the TPCF of isolated and group galaxies when the stellar mass is controlled for. A significant fraction of groups (4/6) with four or more member galaxies do not show any detectable O vi absorption, likely due to the passive nature of the nearest galaxies.}, archive = {J_ApJ}, author = {Sayak Dutta and Sowgat Muzahid and Joop Schaye and Sebastiano Cantalupo and Hsiao-Wen Chen and Sean Johnson}, doi = {10.3847/1538-4357/adabbd}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {264}, shortjournal = {The Astrophys. J.}, title = {MUSEQuBES: The kinematics of o vi-bearing gas in and around low-redshift galaxies}, volume = {980}, year = {2025}, }
• (2025). Evidence for Jet/Outflow shocks heating the environment around the class i protostellar source elias 29: FAUST XXI. ApJ, 980(2), 263. (www)

  @article{ , abstract = {We have observed the late Class I protostellar source Elias 29 at a spatial resolution of 70 au with the Atacama Large Millimeter/submillimeter Array as part of the FAUST Large Program. We focus on the line emission of SO, while that of 34 SO, C 18 O, CS, SiO, H 13 CO + , and DCO + are used supplementarily. The spatial distribution of the SO rotational temperature ( T rot (SO)) is evaluated by using the intensity ratio of its two rotational excitation lines. Besides in the vicinity of the protostar, two hot spots are found at a distance of 500 au from the protostar; T rot (SO) locally rises to 53 {}_{-15}^{+25} K at the interaction point of the outflow and the southern ridge, and 72 {}_{-29}^{+66} K within the southeastern outflow probably due to a jet-driven bow shock. However, the SiO emission is not detected at these hot spots. It is likely that active gas accretion through the disk-like structure and onto the protostar still continues even at this evolved protostellar stage, at least sporadically, considering the outflow/jet activities and the possible infall motion previously reported. Interestingly, T rot (SO) is as high as 20–30 K even within the quiescent part of the southern ridge apart from the protostar by 500–1000 au without clear kinematic indication of current outflow/jet interactions. Such a warm condition is also supported by the low deuterium fractionation ratio of HCO + estimated by using the H 13 CO + and DCO + lines. The B-type star HD147889 ∼0.5 pc away from Elias 29, previously suggested as a heating source for this region, is likely responsible for the warm condition of Elias 29.}, archive = {J_ApJ}, author = {Yoko Oya and Eri Saiga and Anna Miotello and Maria Koutoulaki and Doug Johnstone and Cecilia Ceccarelli and Claire J. Chandler and Claudio Codella and Nami Sakai and Eleonora Bianchi and Mathilde Bouvier and Steven Charnley and Nicolas Cuello and Marta De Simone and Logan Francis and Tomoyuki Hanawa and Izaskun Jiménez-Serra and Laurent Loinard and Francois Menard and Giovanni Sabatini and Charlotte Vastel and Ziwei Zhang and Yuri Aikawa and Felipe O. Alves and Nadia Balucani and Gemma Busquet and Paola Caselli and Emmanuel Caux and Spandan Choudhury and Francois Dulieu and Aurora Durán and Lucy Evans and Davide Fedele and Siyi Feng and Francesco Fontani and Tetsuya Hama and Eric Herbst and Shingo Hirano and Tomoya Hirota and Andrea Isella and Claudine Kahane and Bertrand Lefloch and Romane Le Gal and Hauyu Baobab Liu and Ana López-Sepulcre and Luke T. Maud and María José Maureira and Seyma Mercimek and George Moellenbrock and Shoji Mori and Hideko Nomura and Yasuhiro Oba and Ross O’Donoghue and Satoshi Ohashi and Yuki Okoda and Juan Ospina-Zamudio and Jaime Pineda and Linda Podio and Albert Rimola and Takeshi Sakai and Dominique Segura-Cox and Yancy Shirley and Brian Svoboda and Leonardo Testi and Serena Viti and Naoki Watanabe and Yoshimasa Watanabe and Yichen Zhang and Satoshi Yamamoto}, doi = {10.3847/1538-4357/adabe7}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {263}, shortjournal = {The Astrophys. J.}, title = {Evidence for Jet/Outflow shocks heating the environment around the class i protostellar source elias 29: FAUST XXI}, volume = {980}, year = {2025}, }
• (2025). Multifrequency models of black hole photon rings from low-luminosity accretion disks. ApJ, 980(2), 262. (www)

  @article{ , abstract = {Images of black holes encode both astrophysical and gravitational properties. Detecting highly lensed features in images can differentiate between these two effects. We present an accretion disk emission model coupled to the Adaptive Analytical Ray Tracing ( AART ) code that allows a fast parameter space exploration of black hole photon ring images produced from synchrotron emission from 10 to 670 GHz. As an application, we systematically study several disk models and compute their total flux density, average radii, and optical depth. The model parameters are chosen around fiducial values calibrated to general relativistic magnetohydrodynamic (GRMHD) simulations and observations of M87*. For the parameter space studied, we characterize the transition between optically thin and thick regimes and the frequency at which the first photon ring is observable. Our results highlight the need for careful definitions of photon ring radius in the image domain, as in certain models the highly lensed photon ring is dimmer than the direct emission at certain angles. We find that at low frequencies the ring radii are set by the electron temperature, while at higher frequencies the magnetic field strength plays a more significant role, demonstrating how multifrequency analysis can also be used to infer plasma parameters. Lastly, we show how our implementation can qualitatively reproduce multifrequency black hole images from GRMHD simulations when adding time variability to our disk model through Gaussian random fields. This approach provides a new method for simulating observations from the Event Horizon Telescope and the proposed Black Hole Explorer space mission.}, archive = {J_ApJ}, author = {Tejahni Desire and Alejandro Cárdenas-Avendaño and Andrew Chael}, doi = {10.3847/1538-4357/adac4d}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {262}, shortjournal = {The Astrophys. J.}, title = {Multifrequency models of black hole photon rings from low-luminosity accretion disks}, volume = {980}, year = {2025}, }
• (2025). A bias-free deep learning approach for automated sunspot segmentation. ApJ, 980(2), 261. (www)

  @article{ , abstract = {Solar activities significantly influence space weather and the Earth's environment, necessitating accurate and efficient sunspot detection. This study explores deep learning methods to automate sunspot identification in solar satellite images, keeping personal bias to a minimum. Utilizing observations of the Solar Dynamics Observatory, we leverage active-region data from the Helioseismic Magnetic Imager active-region patches to locate sunspot groups detected between 2011 and 2023. The Morphological Active Contour Without Edges technique is applied to produce pseudo-labels, which are utilized to train the U-Net deep learning architecture, combining their strengths for robust segmentation. Evaluation metrics—including precision, recall, F 1-score, intersection over union, and Dice coefficient—demonstrate the superior performance of U-Net. Our approach achieves a high Pearson correlation coefficient of 0.97 when compared with the sunspot area estimation of the Space Weather Prediction Center and 0.96 in comparison with the Debrecen Photoheliographic Data. This hybrid methodology provides a powerful tool for sunspot identification, offering the improved accuracy and efficiency crucial for space-weather prediction.}, archive = {J_ApJ}, author = {Jing Chen and Norbert G. Gyenge and Ye Jiang and Robertus Erdélyi and Jiajia Liu and Yimin Wang}, doi = {10.3847/1538-4357/adac5e}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {261}, shortjournal = {The Astrophys. J.}, title = {A bias-free deep learning approach for automated sunspot segmentation}, volume = {980}, year = {2025}, }
• (2025). A nonstop aurora? the intriguing radio emission from the rapidly rotating magnetic massive star HR 5907. ApJ, 980(2), 260. (www)

  @article{ , abstract = {HR 5907 (HD 142184) stands out among magnetic OB stars for its rapid rotation, exceptionally hard X-ray emission, and strong magnetic field. High-frequency (>5 GHz) radio emission from the star exhibits an approximately flat spectrum that can be attributed to gyrosynchrotron emission from a dense centrifugal magnetosphere. In a survey of radio emission from massive stars at sub-GHz frequencies, we noticed remarkable low-frequency radio emission from this star, characterized by high circular polarization and brightness temperature, which is inconsistent with the gyrosynchrotron model. We present a follow-up low-frequency radio study of this star with the upgraded Giant Metrewave Radio Telescope in search of emission mechanisms that can go undiagnosed at higher frequencies. We detect variable radio emission characterized by varying degrees of circular polarization (15%–45%) throughout the rotation cycle. The broadband spectral fitting also suggests additional emission components at lower frequencies. We show that the observed emission is likely auroral emission via electron cyclotron maser emission (ECME) and identify this star as a main-sequence radio pulse emitter (MRP). For MRPs, ECME is usually observed as short polarized enhancements near the magnetic nulls of the star. The detection of a high degree of circular polarization (>15%) at all times makes HR 5907 unique among MRPs. This is only the second MRP after ρ Oph C (detected polarization fraction: 0%–60%) that exhibits persistent coherent radio emission attributed to the nearly aligned stellar magnetic and rotational axes.}, archive = {J_ApJ}, author = {Ayan Biswas and Barnali Das and James A. Barron and Gregg A. Wade and Gonzalo Holgado}, doi = {10.3847/1538-4357/adae02}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {260}, shortjournal = {The Astrophys. J.}, title = {A nonstop aurora? the intriguing radio emission from the rapidly rotating magnetic massive star HR 5907}, volume = {980}, year = {2025}, }
• (2025). Asymmetric temperature variations in protoplanetary disks. i. linear theory, corotating spirals, and ring formation. ApJ, 980(2), 259. (www)

  @article{ , abstract = {Protoplanetary disks can exhibit asymmetric temperature variations due to phenomena such as shadows cast by the inner disk or localized heating by young planets. We investigate the disk features induced by these asymmetric temperature variations. We find that spirals are initially excited, and then break into two and reconnect to form rings. By carrying out linear analyses, we first study the spiral launching mechanism and find that the effects of azimuthal temperature variations share similarities with effects of external potentials. Specifically, rotating temperature variations launch steady spiral structures at Lindblad resonances, which corotate with the temperature patterns. When the cooling time exceeds the orbital period, these spiral structures are significantly weakened, and a checkerboard pattern may appear. A temperature variation of about 10% can induce spirals with order unity density perturbations, comparable to those generated by a thermal mass planet. We then study ring formation and find it is related to the coupling between azimuthal temperature variations and spirals outside the resonances. Such coupling leads to a radially varying angular momentum flux, which produces anomalous wave-driven accretion and forms dense rings separated by the wavelength of the waves. Finally, we speculate that spirals induced by temperature variations may contribute to disk accretion through nonlinear wave steepening and dissipation. Overall, considering that irradiation determines the temperature structure of protoplanetary disks, the change of irradiation both spatially or/and temporarily may produce observable effects in protoplanetary disks, especially spirals and rings in outer disks beyond tens of au.}, archive = {J_ApJ}, author = {Zhaohuan Zhu and Shangjia Zhang and Ted M. Johnson}, doi = {10.3847/1538-4357/adae0d}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {259}, shortjournal = {The Astrophys. J.}, title = {Asymmetric temperature variations in protoplanetary disks. i. linear theory, corotating spirals, and ring formation}, volume = {980}, year = {2025}, }
• (2025). Fast and efficient bayesian method to search for strongly lensed gravitational waves. ApJ, 980(2), 258. (www)

  @article{ , abstract = {A small fraction of the gravitational-wave (GW) signals from binary black holes observable by ground-based detectors will be strongly lensed by intervening objects such as galaxies and clusters. Strong lensing will produce nearly identical copies of the GW signals separated in time. These lensed signals must be identified against a background of unlensed pairs GW events, some of which may appear similar by accident. This is usually done using fast, but approximate methods that, for example, check for the overlap between the posterior distributions of a subset of binary parameters, or using slow, but accurate joint Bayesian parameter estimation. In this work, we present a modified version of the posterior overlap method dubbed "PO2.0" that is mathematically equivalent to joint parameter estimation while still remaining fast. We achieve a significant gain in efficiency by incorporating informative priors about the binary and lensing populations, selection effects, and all the inferred parameters of the binary. For binary black hole signals lensed by galaxies, our improved method can detect 65% lensed events at a pairwise false alarm probability of ∼2 × 10 −6 . Consequently, we have a 13% probability of detecting a strongly lensed event above 2.25 σ significance during 18 months of observation by the LIGO-Virgo detectors at their current sensitivity. We also show how we can compute the joint posteriors of the lens and source parameters from a pair of lensed events by reweighting the posteriors of individual events in a computationally inexpensive way.}, archive = {J_ApJ}, author = {Ankur Barsode and Srashti Goyal and Parameswaran Ajith}, doi = {10.3847/1538-4357/adae10}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {258}, shortjournal = {The Astrophys. J.}, title = {Fast and efficient bayesian method to search for strongly lensed gravitational waves}, volume = {980}, year = {2025}, }
• (2025). Extracting the X-ray reverberation response functions from the active galactic nucleus light curves using an autoencoder. ApJ, 980(2), 257. (www)

  @article{ , abstract = {We study the X-ray reverberation in active galactic nuclei (AGN) using the variational autoencoder (VAE), which is a machine learning algorithm widely used for signal processing and feature reconstruction. While the X-ray reverberation signatures that contain the information of the accretion disk and the X-ray-emitting corona are commonly analyzed in the Fourier domain, this work aims to extract the reverberation response functions directly from the AGN light curves. The VAE is trained using the simulated light curves that contain the primary X-rays from the lamppost corona, varying its height and the corresponding reflection X-rays from the disk. We use progressively more realistic light-curve models, such as those that include the effects of disk-propagating fluctuations and random noises, to assess the ability of the VAE to reconstruct the response profiles. Interestingly, the VAE can recognize the reverberation patterns on the light curves; hence, the coronal height can be predicted. We then deploy the VAE model on the XMM-Newton data of IRAS 13224–3809 and directly estimate, for the first time, the response functions of this source in various observations. The result reveals the corona changing its height between 3 r g and 20 r g , which is correlated with the source luminosity and in line with previous literature. Finally, we discuss the advantages and limitations of this method.}, archive = {J_ApJ}, author = {Sanhanat Deesamutara and Poemwai Chainakun and Tirawut Worrakitpoonpon and Kamonwan Khanthasombat and Wasutep Luangtip and Jiachen Jiang and Francisco Pozo Nuñez and Andrew J. Young}, doi = {10.3847/1538-4357/adae85}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {257}, shortjournal = {The Astrophys. J.}, title = {Extracting the X-ray reverberation response functions from the active galactic nucleus light curves using an autoencoder}, volume = {980}, year = {2025}, }
• (2025). Studying the radiation of a white dwarf star falling onto a black hole. ApJ, 980(2), 256. (www)

  @article{ , abstract = {We investigate electromagnetic and gravitational radiation generated during the process of the tidal stripping of a white dwarf star circulating a black hole. We go beyond Chandrasekhar's ideas and not only consider the white dwarf itself as a quantum object, but also describe the dynamics of the produced accretion disk in a quantum way. We model the white dwarf star as a Bose–Fermi droplet and use the quantum hydrodynamic equations to simulate the evolution of the black hole–white dwarf binary system. While going through periastron, the white dwarf loses a small fraction of its mass. The mass falling onto a black hole is a source of powerful electromagnetic and gravitational radiation. Bursts of ultraluminous radiation are flared at each periastron passage. This resembles the recurrent flaring of X-ray sources discovered recently by Irwin et al. Gravitational energy bursts occur mainly through emission at very low frequencies. The accretion disk, formed due to stripping of the white dwarf, starts at some point to contribute continuously to radiation of both electromagnetic and gravitational types.}, archive = {J_ApJ}, author = {Marek Nikołajuk and Tomasz Karpiuk and Lorenzo Ducci and Mirosław Brewczyk}, doi = {10.3847/1538-4357/adae8c}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {256}, shortjournal = {The Astrophys. J.}, title = {Studying the radiation of a white dwarf star falling onto a black hole}, volume = {980}, year = {2025}, }
• (2025). Could the neutrino emission of TXS 0506+056 come from the accretion flow of the supermassive black hole?. ApJ, 980(2), 255. (www)

  @article{ , abstract = {High-energy neutrinos from the blazar TXS 0506+056 are usually thought to arise from the relativistic jet pointing to us. However, the composition of jets of active galactic nuclei (AGNs), whether they are baryon dominated or Poynting flux dominated, is largely unknown. In the latter case, no comic rays and neutrinos would be expected from the AGN jets. In this work, we study whether the neutrino emission from TXS 0506+056 could be powered by the accretion flow of the supermassive black hole. Protons could be accelerated by magnetic reconnection or turbulence in the inner accretion flow. To explain the neutrino flare of TXS 0506+056 in the years 2014–2015, a super-Eddington accretion is needed. During the steady state, a sub-Eddington accretion flow could power a steady neutrino emission that may explain the long-term neutrino flux from TXS 0506+056. We consider the neutrino production in both magnetically arrested accretion (MAD) flow and the standard and normal evolution (SANE) regime of accretion. In the MAD scenario, due to a high magnetic field, a large dissipation radius is required to avoid the cooling of protons and secondary pions.}, archive = {J_ApJ}, author = {Qi-Rui Yang and Ruo-Yu Liu and Xiang-Yu Wang}, doi = {10.3847/1538-4357/adaea4}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {255}, shortjournal = {The Astrophys. J.}, title = {Could the neutrino emission of TXS 0506+056 come from the accretion flow of the supermassive black hole?}, volume = {980}, year = {2025}, }
• (2025). Study on the responses in the transition region of coronal extreme-ultraviolet waves. ApJ, 980(2), 254. (www)

  @article{ , abstract = {Coronal extreme-ultraviolet (EUV) waves are globally propagating disturbances in the solar atmosphere. The existence of coronal EUV waves was predicted by chromospheric Moreton–Ramsey waves. It is widely accepted that Moreton–Ramsey waves represent the chromospheric imprints of coronal EUV waves that compress downward during their lateral propagations. Hence, coronal EUV waves should inevitably compress the interlayer between the corona and the chromosphere, the transition region (TR), before reaching the chromosphere. However, the responses in the TR of coronal EUV waves lack enough attention. Here, we focus on the wave signatures in He ii 304 Å for a sample of 640 coronal EUV waves from 2010 to 2021, aiming to establish a "bridge" connecting coronal EUV waves and chromospheric Moreton–Ramsey waves. It is found that ∼14.4% of all coronal EUV waves have TR responses, and ∼34.5% of "disk events" with TR responses have chromospheric imprints. We specifically analyze the wave front characteristics of disk events with TR responses (58). Statistical analysis shows that TR responses for coronal EUV waves have an average speed of 495.58 ± 27.62 km s −1 , an average duration of 488.4 ± 12 s, an average angular width of 71 \mathop{.}\limits^{\unicode{x000b0}} 22, and an average intensity enhancement ratio (IER) of 30.39%. Moreover, all TR responses with chromospheric imprints display a greater inclination angle (>50°) and a larger IER (>30%). All the results suggest that TR responses can be indicators of missing Moreton–Ramsey waves and clarify the resolution of the mystery of the rarity of Moreton–Ramsey waves.}, archive = {J_ApJ}, author = {Xiaoqian Wang and Ruisheng Zheng and Yihan Liu and Xuechao Zhang and Liang Zhang and Jun Li and Yao Chen}, doi = {10.3847/1538-4357/adb035}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {254}, shortjournal = {The Astrophys. J.}, title = {Study on the responses in the transition region of coronal extreme-ultraviolet waves}, volume = {980}, year = {2025}, }
• (2025). Stream members only: Data-driven characterization of stellar streams with mixture density networks. ApJ, 980(2), 253. (www)

  @article{ , abstract = {Stellar streams are sensitive probes of the Milky Way's gravitational potential. The mean track of a stream constrains global properties of the potential, while its fine-grained surface density constrains galactic substructure. A precise characterization of streams from potentially noisy data marks a crucial step in inferring galactic structure, including the dark matter, across orders of magnitude in mass scales. Here we present a new method for constructing a smooth probability density model of stellar streams using all of the available astrometric and photometric data. To characterize a stream's morphology and kinematics, we utilize mixture density networks to represent its on-sky track, width, stellar number density, and kinematic distribution. We model the photometry for each stream as a single-stellar population, with a distance track that is simultaneously estimated from the stream's inferred distance modulus (using photometry) and parallax distribution (using astrometry). We use normalizing flows to characterize the distribution of background stars. We apply the method to the stream GD-1, and the tidal tails of Palomar 5. For both streams we obtain a catalog of stellar membership probabilities that are made publicly available. Importantly, our model is capable of handling data with incomplete phase-space observations, making our method applicable to the growing census of Milky Way stellar streams.}, archive = {J_ApJ}, author = {Nathaniel Starkman and Jacob Nibauer and Jo Bovy and Jeremy J. Webb and Kiyan Tavangar and Adrian Price-Whelan and Ana Bonaca}, doi = {10.3847/1538-4357/ad94f2}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {253}, shortjournal = {The Astrophys. J.}, title = {Stream members only: Data-driven characterization of stellar streams with mixture density networks}, volume = {980}, year = {2025}, }
• (2025). Turbulence and magnetic field alignment in small molecular clouds: The role of cloud size, mass, and density. ApJ, 980(2), 252. (www)

  @article{ , abstract = {In this study, we investigate the relationship between turbulence (Δ V ) and different physical parameters in 22 isolated small molecular clouds and their cores, extending the analysis to a hierarchical scenario from core to cloud. Using 12 CO line width as a tracer of turbulence, we find that Δ V correlates with both cloud size and mass, following \propto {({L}_{\mathrm{cl}})}^{0.30\pm 0.04} and \propto {({M}_{\mathrm{cl}})}^{0.21\pm 0.08} . Further, the surface density of the clouds (Σ cl ) influences the Δ V – L cl relation, with {\rm{\Delta }}V\propto {({L}_{\mathrm{cl}}\times {\Sigma }_{\mathrm{cl}})}^{0.50\pm 0.13} . This indicates that gravitational energy drives turbulence in clouds, indicating possible virial equilibrium. We observe that L cl correlates with M cl and volume gas density of the cloud ( ρ cl ), implying nearly constant Σ cl across the clouds. In cloud cores, C 18 O line-width data show complex behavior, with no direct correlation between Δ V and core size ( L co ). However, a positive correlation emerges when the surface density of the core is included in L co . Notably, the relation between volume gas density ( ρ co ) and core size ( L co ) deviates from constant core surface density. Our analysis reveals that turbulent pressure increases with gravitational pressure to maintain global equilibrium. Finally, on the core-to-cloud scale, physical relationships remain continuous, reflecting the interconnected nature of clouds and cores. Extending our previous work, where we demonstrated a nonlinear dependence of turbulence on the alignment of the local magnetic field in molecular clouds with the Galactic plane, we now compare observations with a theoretical model based on kinetic theory. Our result confirms that higher turbulence causes greater magnetic misalignment consistent with the derived second-order polynomial relationship.}, archive = {J_ApJ}, author = {Bhaskarjyoti Barman and Himadri Sekhar Das and Pritibhajan Byakti}, doi = {10.3847/1538-4357/ada562}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {252}, shortjournal = {The Astrophys. J.}, title = {Turbulence and magnetic field alignment in small molecular clouds: The role of cloud size, mass, and density}, volume = {980}, year = {2025}, }
• (2025). Geometry of the comptonization region of MAXI j1348−630 through type-C quasiperiodic oscillations with NICER. ApJ, 980(2), 251. (www)

  @article{ , abstract = {We use the rms and lag spectra of the type-C quasiperiodic oscillation (QPO) to study the properties of the Comptonization region (aka corona) during the low/hard and hard-intermediate states of the main outburst and reflare of MAXI J1348−630. We simultaneously fit the time-averaged energy spectrum of the source and the fractional rms and phase-lag spectra of the QPO with the time-dependent Comptonization model VKOMPTH. The data can be explained by two physically connected coronae interacting with the accretion disk via a feedback loop of X-ray photons. The best-fitting model consists of a corona of ∼10 3 km located at the inner edge of the disk and a second corona of ∼10 4 km horizontally extended and covering the inner parts of the accretion disk. The properties of both coronae during the reflare are similar to those during the low/hard state of the main outburst, reinforcing the idea that both the outburst and the reflare are driven by the same physical mechanisms. We combine our results for the type-C QPO with those from previous work focused on the study of type-A and type-B QPOs with the same model to study the evolution of the geometry of the corona through the whole outburst, including the reflare of MAXI J1348−630. Finally, we show that the sudden increase in the phase-lag frequency spectrum and the sharp drop in the coherence function previously observed in MAXI J1348−630 are due to the type-C QPO during the decay of the outburst and can be explained in terms of the geometry of the coronae.}, archive = {J_ApJ}, author = {Kevin Alabarta and Mariano Méndez and Federico García and Diego Altamirano and Yuexin Zhang and Liang Zhang and David M. Russell and Ole König}, doi = {10.3847/1538-4357/ada7f9}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {251}, shortjournal = {The Astrophys. J.}, title = {Geometry of the comptonization region of MAXI j1348−630 through type-C quasiperiodic oscillations with NICER}, volume = {980}, year = {2025}, }
• (2025). Effect of lyα radiative transfer on intensity mapping power spectra. ApJ, 980(2), 250. (www)

  @article{ , abstract = {Clustering of Ly α -emitting galaxies (LAEs) and Ly α line intensity mapping (LIM) are useful probes of cosmology. However, Ly α radiative transfer (RT) effects, such as absorption, line shift, and line broadening, and their dependence on the large-scale density and velocity fields can modify the measured LAE clustering and LIM statistics. We explore the effects of RT on the Ly α LIM power spectrum in two ways: using an analytic description based on linear approximations, and using lognormal mocks. The qualitative effects of intergalactic Ly α absorption on the LIM auto- and cross-power spectrum include a scale-dependent, reduced effective bias, reduced mean intensity, and modified redshift-space distortions. The linear absorption model does not describe the results of the lognormal simulations well. The random line shift suppresses the redshift-space power spectrum similar to the Fingers-of-God effect. In cross-correlation of LAEs or Ly α intensity with a non-Ly α tracer, the Ly α line shift leads to a phase shift of the complex power spectrum, i.e., a cosine damping of the real part. We study the impact of Ly α RT effects on the Hobby–Eberly Telescope Dark Energy Experiment (HETDEX) LAE and LIM power spectra using lognormal mocks. We find that even small amounts of IGM absorption will significantly change the measured LAE auto-power spectrum. The LAE-intensity cross-power spectrum stays within the measurement uncertainty. Therefore, HETDEX will be able to constrain Ly α RT effects.}, archive = {J_ApJ}, author = {Maja Lujan Niemeyer}, doi = {10.3847/1538-4357/ada8a3}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {250}, shortjournal = {The Astrophys. J.}, title = {Effect of lyα radiative transfer on intensity mapping power spectra}, volume = {980}, year = {2025}, }
• (2025). Can dark stars account for the star formation efficiency excess at very high redshifts?. ApJ, 980(2), 249. (www)

  @article{ , abstract = {The James Webb Space Telescope (JWST) has recently conducted observations of massive galaxies at high redshifts, revealing a notable anomaly in their star formation efficiency (SFE). Motivated by the recent identification of three ~10 6 M ⊙ dark star candidates, we investigate whether dark stars can be the origin of the SFE excess. It turns out that the excess can be reproduced by a group of dark stars with M ≳ 10 3 M ⊙ , because of their domination in generating primary UV radiation in high-redshift galaxies. The genesis of these dark stars is attributed to the capture of weakly interacting massive particles within a mass range of tens of gigaelectronvolts to a few teraelectronvolts. However, if the top-heavy initial mass function of dark stars holds up to ~10 5 M ⊙ , the relic black holes stemming from their collapse would be too abundant to be consistent with the current observations of massive compact halo objects. We thus suggest that just a small fraction of SFE excess may be contributed by the very massive dark stars, with the majority likely originating from other sources, such as the Population III stars, in view of their rather similar UV radiation efficiencies.}, archive = {J_ApJ}, author = {Lei Lei and Yi-Ying Wang and Guan-Wen Yuan and Tong-Lin Wang and Martin A. T. Groenewegen and Yi-Zhong Fan}, doi = {10.3847/1538-4357/ada93b}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {249}, shortjournal = {The Astrophys. J.}, title = {Can dark stars account for the star formation efficiency excess at very high redshifts?}, volume = {980}, year = {2025}, }
• (2025). Chemical evolution of isotopically labeled carbon dioxide (13CO2) ice exposed to ionizing radiation and implications for trans-neptunian objects. ApJ, 980(2), 248. (www)

  @article{ , abstract = {We present results on the radiation chemistry of isotopically labeled carbon dioxide ( 13 CO 2 ) ices induced by energetic electrons at 40 and 10 K to simulate the chemical evolution of carbon dioxide on trans-Neptunian objects exposed to galactic cosmic-ray particles. By collecting infrared spectra during the irradiation of 13 CO 2 ices, we have identified several radiolysis products, including carbon monoxide ( 13 CO), ozone (O 3 ), carbon trioxide ( 13 CO 3 ) with cyclic ( C 2 v ) and acyclic ( D 3 h ) isomers, carbon tetraoxide ( 13 CO 4 ), carbon pentaoxide ( 13 CO 5 ), and carbon hexaoxide ( 13 CO 6 ). The temporal profiles reveal that all products exhibit a rapid increase followed by a gradual decrease during prolonged irradiation, with the reduction at 40 K occurring faster than at 10 K. Furthermore, the ratio of 13 CO to 13 CO 2 rises to constants of 0.20 at 40 K and 0.27 at 10 K as radiation accumulates within ices, which has potential implications for understanding the specific conditions of trans-Neptunian objects, such as galactic cosmic-ray exposure history, or other astrophysical scenarios characterized by abundant carbon dioxide.}, archive = {J_ApJ}, author = {Chaojiang Zhang and Leslie A. Young and Ralf I. Kaiser}, doi = {10.3847/1538-4357/ada9e7}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {248}, shortjournal = {The Astrophys. J.}, title = {Chemical evolution of isotopically labeled carbon dioxide (13CO2) ice exposed to ionizing radiation and implications for trans-neptunian objects}, volume = {980}, year = {2025}, }
• (2025). Exploring the neutrino mass hierarchy from isotopic ratios of supernova nucleosynthesis products in presolar grains. ApJ, 980(2), 247. (www)

  @article{ , abstract = {We study the nucleosynthesis in a core-collapse supernova (CCSN) model including newly calculated neutrino-induced reaction rates with both collective and Mikheyev–Smirnov–Wolfenstein neutrino flavor oscillations considered. We show that the measurement of a pair of 11 B/ 10 B and 138 La/ 139 La or 6 Li/ 7 Li and 138 La/ 139 La in presolar grains that are inferred to have originated from CCSNs could constrain the neutrino mass hierarchy. The new shell model and the model of quasiparticle random phase approximation in the estimate of three important neutrino-induced reactions, ν + 16 O, ν + 20 Ne, and ν + 138 Ba, are applied in our reaction network. The new rates decrease the calculated 7 Li/ 6 Li ratio by a factor of 5 compared with the previous study. More interestingly, these new rates result in a clear separation of the isotopic ratio of 11 B/ 10 B between normal and inverted mass hierarchies in the O/Ne, O/C, and C/He layers, where 138 La abundance depends strongly on the mass hierarchy. In these layers, the sensitivity of the calculated abundances of 10,11 B and 6,7 Li to the nuclear reaction uncertainties is also tiny. Therefore, we propose that the 11 B/ 10 B versus 138 La/ 139 La and 6 Li/ 7 Li versus 138 La/ 139 La in type X silicon carbide grains sampled material from C/He layer can be used as a new probe to constrain the neutrino mass hierarchy.}, archive = {J_ApJ}, author = {Xingqun Yao and Toshitaka Kajino and Yudong Luo and Takehito Hayakawa and Toshio Suzuki and Heamin Ko and Myung-Ki Cheoun and Seiya Hayakawa and Hidetoshi Yamaguchi and Silvio Cherubini}, doi = {10.3847/1538-4357/adaaf2}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {247}, shortjournal = {The Astrophys. J.}, title = {Exploring the neutrino mass hierarchy from isotopic ratios of supernova nucleosynthesis products in presolar grains}, volume = {980}, year = {2025}, }
• (2025). Planetary rhythms: Synchronous circulation on variably irradiated asynchronous planets. ApJ, 980(2), 246. (www)

  @article{ , abstract = {Tidal locking of planets to their host stars results in an atmospheric circulation with a hotspot fixed to the frame of reference of the planet. On the other hand, asynchronously rotating planets feature moving hotspots either lagging or leading the corresponding substellar point as it translates along the surface. We show that a planet falling in the latter category could mimic the circulation of tidally synchronous planets under the influence of time-varying instellation, possibly provided by pulsating or multiple star systems. This happens when the planet's diurnal period is in resonance with the period of instellation variation, leading to a planet-frame-fixed hotspot. Slight differences in the above periods lead to east–west or west–east creeping hotspots with a period significantly longer than both. The rate of hotspot motion is given by the difference between the diurnal and instellation variation rates, similar to the lower envelope frequency of beat patterns formed by two superposed waves in linear wave theory. We call this phenomenon "beating." A combination of the radiative, rotational, wave propagation, and drag timescales establishes dynamical constraints on beating. Based on this, we classify a set of Kepler and TESS circumbinary planets with two candidates exhibiting climatic departures from the no-variation scenario. In general, hotter and faster-spinning planets are more susceptible to climatic departures. Beating, if it occurs, may additionally create optimistic extensions of habitable zones for corresponding systems.}, archive = {J_ApJ}, author = {Deepayan Banik}, doi = {10.3847/1538-4357/adabc4}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {246}, shortjournal = {The Astrophys. J.}, title = {Planetary rhythms: Synchronous circulation on variably irradiated asynchronous planets}, volume = {980}, year = {2025}, }
• (2025). Measuring the intracluster light fraction with machine learning. ApJ, 980(2), 245. (www)

  @article{ , abstract = {The intracluster light (ICL) is an important tracer of a galaxy cluster's history and past interactions. However, only small samples have been studied to date due to its very low surface brightness and the heavy manual involvement required for the majority of measurement algorithms. Upcoming large imaging surveys such as the Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST) are expected to vastly expand available samples of deep cluster images. However, to process this increased amount of data, we need faster, fully automated methods to streamline the measurement process. This paper presents a machine learning model designed to automatically measure the ICL fraction in large samples of images, with no manual preprocessing required. We train the fully supervised model on a training data set of 50,000 images with injected artificial ICL profiles. We then transfer its learning onto real data by fine-tuning with a sample of 101 real clusters with their ICL fraction measured manually using the surface brightness threshold method. With this process, the model is able to effectively learn the task and then adapt its learning to real cluster images. Our model can be directly applied to Hyper Suprime-Cam images, processing up to 500 images in a matter of seconds on a single GPU, or fine-tuned for other imaging surveys such as LSST, with the fine-tuning process taking just 3 minutes. The model could also be retrained to match other ICL measurement methods. Our model and the code for training it are made available on GitHub.}, archive = {J_ApJ}, author = {Louisa Canepa and Sarah Brough and Francois Lanusse and Mireia Montes and Nina Hatch}, doi = {10.3847/1538-4357/adabc7}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {245}, shortjournal = {The Astrophys. J.}, title = {Measuring the intracluster light fraction with machine learning}, volume = {980}, year = {2025}, }
• (2025). Modeling tidal streams and tidal tails around galaxies using deep wendelstein imaging data. ApJ, 980(2), 244. (www)

  @article{ , abstract = {From the Λ cold dark matter paradigm, it is expected that galaxies merge and grow in their environments. These processes form various tidal features depending on the merger mass ratio, orbital parameters, and gas richness. We inspected 170 g^{\prime} -band Abell cluster observations from the 2.1 m Fraunhofer-Teleskop Wendelstein and identify 111 of such features from which we select nine streams and five tails. A fast and innovative technique was developed for determining their photometric properties. The model is a Gaussian, including higher-order moments to describe the light profile in slices perpendicular to the elongation direction. From these models, FWHM apertures are generated. The method was developed, tested, and applied on the selected features and corresponding g - and r -band data from the Legacy Survey DR10. Regarding the novel modeling approach, we can measure surface and total brightnesses with precisions of 4% and 7%, respectively. Mean stream width precision, which also translates to the mean R e along the feature is on average within 3% uncertainty. The measured streams have on average a surface brightness of \sim 26.25\,g^{\prime} mag arcsec −2 and are dimmer than the tails in our sample ( \sim 25.14\,g^{\prime} mag arcsec −2 ). We infer that the progenitors of our streams can come from dwarfs, early-type galaxies or disks, based on the streams structural parameters. Furthermore, brightnesses and colors of the streams and tails are consistent with those of galaxies that populate the red sequence in the Coma cluster within 2 σ .}, archive = {J_ApJ}, author = {Jan-Niklas Pippert and Matthias Kluge and Ralf Bender}, doi = {10.3847/1538-4357/adabda}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {244}, shortjournal = {The Astrophys. J.}, title = {Modeling tidal streams and tidal tails around galaxies using deep wendelstein imaging data}, volume = {980}, year = {2025}, }
• (2025). A method for estimating X-ray pulsar period and pulse time delay: Applying the improved ${Z}_{n,\mathrm{bin}}^{2}$-test to complex profiles. ApJ, 980(2), 243. (www)

  @article{ , abstract = {In order to apply the Z 2 statistic to the estimation of the navigation pulsar period and time delay, and thus further improve the accuracy of X-ray pulsar navigation, this paper proposes a method for estimating the pulsar period and time delay with complex profiles based on the improved {Z}_{n,\mathrm{bin}}^{2} -test. Based on the prior information of the amount of photon data in the observation task, this method adaptively determines the optimal harmonic truncation order under different data qualities. In order to solve the problem of the change rate of complex profile signals being too fast, the binned data is rephased according to the principle of equal photon intensity segmentation within the bin, and the optimal number of bins suitable for the PSR B0531+21 pulsar is selected. Through simulation, a quantitative analysis was conducted on factors that affect the performance of the estimation algorithm, such as observation time, detector area, noise interference, etc. Simulation results show that the proposed estimation method has greater advantages when the observation time is short, the detector area is small, and the interference noise is large. In addition, the observation data of the PSR B0531+21 pulsar is processed and analyzed. The period estimation accuracy of the method proposed is 3.6532 ns, which is 39.57% higher than that of the χ 2 -test method. The method we proposed has the advantages of being suitable for navigation pulsars, strong environmental adaptability, high estimation accuracy, and strong estimation stability, which can further improve the performance of X-ray pulsar navigation.}, archive = {J_ApJ}, author = {T. H. Xie and W. J. Zhang and J. R. Li and Y. Hao and P. L. Cui and X. L. Ning and X. Ma}, doi = {10.3847/1538-4357/adad5f}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {243}, shortjournal = {The Astrophys. J.}, title = {A method for estimating X-ray pulsar period and pulse time delay: Applying the improved ${Z}_{n,\mathrm{bin}}^{2}$-test to complex profiles}, volume = {980}, year = {2025}, }
• (2025). The AURORA survey: A new era of emission-line diagrams with JWST/NIRSpec. ApJ, 980(2), 242. (www)

  @article{ , abstract = {We present results on the emission-line properties of z = 1.4–7.5 star-forming galaxies in the Assembly of Ultradeep Rest-optical Observations Revealing Astrophysics (AURORA) Cycle 1 JWST/NIRSpec program. Based on its depth, continuous wavelength coverage from 1 to 5 μ m, and medium spectral resolution ( R ∼ 1000), AURORA includes detections of a large suite of nebular emission lines spanning a broad range in rest-frame wavelength. We investigate the locations of AURORA galaxies in multiple different emission-line diagrams, including traditional BPT diagrams of [O iii ] λ 5007/H β versus [N ii ] λ 6583/H α , [S ii ] λλ 6717, 6731/H α , and [O i ] λ 6300/H α , and the ionization–metallicity diagram of [O iii ] λ 5007/[O ii ] λ 3727 (O 32 ) versus ([O iii ] λ 5007+[O ii ] λ 3727)/H β ( R 23 ). We also consider a bluer rest-frame ionization–metallicity diagram introduced recently to characterize z > 10 galaxies, [Ne iii ] λ 3869/[O ii ] λ 3727 versus ([Ne iii ] λ 3869+[O ii ] λ 3727)/H δ , as well as longer-wavelength diagnostic diagrams extending into the rest-frame near-IR: [O iii ] λ 5007/H β versus [S iii ] λλ 9069, 9532/[S ii ] λλ 6717, 6731 (S 32 ), and He i λ 1.083 μ m/Pa γ and [S iii ] λ 9532/Pa γ versus [Fe ii ] λ 1.257 μ m/Pa β . With a significant boost in signal-to-noise ratio and large, representative samples of individual galaxy detections, the AURORA emission-line diagrams presented here definitively confirm a physical picture in which chemically young, α -enhanced, massive stars photoionize the interstellar medium (ISM) in distant galaxies with a harder ionizing spectrum at fixed nebular metallicity than in their z ∼ 0 counterparts. We also uncover previously unseen evolution prior to z ∼ 2 in the [O iii ] λ 5007/H β versus [N ii ] λ 6583/H α diagram, which motivates deep NIRSpec observations at even higher redshift. Finally, we present the first statistical sample of rest-frame near-IR emission-line diagnostics in star-forming galaxies at high redshift. In order to truly interpret rest-frame near-IR line ratios including [Fe ii ] λ 1.257 μ m, we must obtain better constraints on dust depletion in the high-redshift ISM.}, archive = {J_ApJ}, author = {Alice E. Shapley and Ryan L. Sanders and Michael W. Topping and Naveen A. Reddy and Danielle A. Berg and Rychard J. Bouwens and Gabriel Brammer and Adam C. Carnall and Fergus Cullen and Romeel Davé and James S. Dunlop and Richard S. Ellis and N. M. Förster Schreiber and Steven R. Furlanetto and Karl Glazebrook and Garth D. Illingworth and Tucker Jones and Mariska Kriek and Derek J. McLeod and Ross J. McLure and Desika Narayanan and Pascal Oesch and Anthony J. Pahl and Max Pettini and Daniel Schaerer and Daniel P. Stark and Charles C. Steidel and Mengtao Tang and Leonardo Clarke and Callum T. Donnan and Emily Kehoe}, doi = {10.3847/1538-4357/adad68}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {242}, shortjournal = {The Astrophys. J.}, title = {The AURORA survey: A new era of emission-line diagrams with JWST/NIRSpec}, volume = {980}, year = {2025}, }
• (2025). GRB 221009A and the apparently most energetic gamma-ray bursts. ApJ, 980(2), 241. (www)

  @article{ , abstract = {Gamma-ray bursts (GRBs) are often referred to as the most luminous explosions in the Universe, due to their short and highly luminous prompt emission. This apparent luminosity, however, does not reflect the true energy budget of the prompt emission, which is strongly beamed. Accurate estimations of the energy radiated during the prompt phase require taking the geometry of GRB jets into account, which remains poorly known. Nevertheless, one may establish the distribution of well-measured quantities, like E iso , the GRB isotropic equivalent energy, which encrypts crucial information about GRB jets, with the aim of providing constraints on the jet's radiated energy. In this work, we study the bright end of the GRB isotropic equivalent energy distribution (hereafter called "apparent energy"), using an updated sample of 185 apparently energetic GRBs with E iso ≥ 10 53 erg. This new sample includes GRB 221009A, allowing us to discuss this apparently superenergetic GRB in the context of the general E iso distribution of long GRBs. We describe the construction of the sample and compare three fits of the E iso distribution with a simple power law, a cutoff power law, and a broken power law. Our study confirms the existence of a cutoff around E iso = 4 × 10 54 erg, even when GRB 221009A is included in the sample. Based on this finding, we discuss the possible reasons behind the rapid decrease in the number of apparently energetic gamma-ray bursts beyond E iso = 4 × 10 54 erg and the interpretation of GRB 221009A, the most apparently energetic GRB detected to date, in this context.}, archive = {J_ApJ}, author = {Jean-Luc Atteia and Laurent Bouchet and Jean-Pascal Dezalay and Francis Fortin and Olivier Godet and Sébastien Guillot and Alain Klotz and Frédéric Daigne and Robert Mochkovitch and Damien Turpin}, doi = {10.3847/1538-4357/adadef}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {241}, shortjournal = {The Astrophys. J.}, title = {GRB 221009A and the apparently most energetic gamma-ray bursts}, volume = {980}, year = {2025}, }
• (2025). Understanding streaming instabilities in the limit of high cosmic-ray current density. ApJ, 980(2), 240. (www)

  @article{ , abstract = {A critical component of particle acceleration in astrophysical shocks is the nonresonant (Bell) instability, where the streaming of cosmic rays (CRs) leads to the amplification of magnetic fields necessary to scatter particles. In this work we use kinetic particle-in-cell simulations to investigate the high-CR-current regime, where the typical assumptions underlying the Bell instability break down. Despite being more strongly driven, significantly less magnetic field amplification is observed than in low-current cases, an effect due to the anisotropic heating that occurs in this regime. We also find that electron-scale modes, despite being the fastest growing, mostly lead to moderate electron heating and do not affect the late evolution or saturation of the instability.}, archive = {J_ApJ}, author = {Emily Lichko and Damiano Caprioli and Benedikt Schroer and Siddhartha Gupta}, doi = {10.3847/1538-4357/adadf5}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {240}, shortjournal = {The Astrophys. J.}, title = {Understanding streaming instabilities in the limit of high cosmic-ray current density}, volume = {980}, year = {2025}, }
• (2025). Radio polarization from runaway star bowshocks. i. the general case. ApJ, 980(2), 239. (www)

  @article{ , abstract = {High velocity stars move through the interstellar medium with V > 30 km s −1 . When the star has powerful winds, under the appropriate conditions, the interaction of the wind with the interstellar material produces a system of shocks. The outer shock, called the bowshock, perturbs the ambient medium, heating and compressing the gas. The dust in the compressed bowshock cools, producing infrared radiation. This emission appears as extended coma-shape structures. The discovery of radio nonthermal emission from two stellar bowshock nebulae indicates that these sources might be accelerating electrons up to relativistic energies. The produced nonthermal radio emission is most probably synchrotron, which has a high degree of polarization. In this work we model the synchrotron emission of runaway massive star bowshocks aiming to produce synthetic radio emission and polarization maps for two frequencies: 1.40 and 4.86 GHz. We model the interacting plasmas in a steady-state regime by means of magnetohydrodynamics simulations and we compute the injection and transport of the relativistic electrons in the diffusion approximation. We include in the model the most important depolarization effects. Our main conclusions are (i) the effects of Faraday rotation within the source are important at the lowest frequency considered, (ii) inferring the local magnetic field direction from polarization measurements only can be misleading, (iii) thermal radio emission produced by ionized plasma within the bowshock structure and surroundings can surpass the polarized one for the considered frequencies, and (iv) the contribution from the background electrons is minor.}, archive = {J_ApJ}, author = {M. V. del Valle and R. Santos-Lima and M. Pohl}, doi = {10.3847/1538-4357/adae0a}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {239}, shortjournal = {The Astrophys. J.}, title = {Radio polarization from runaway star bowshocks. i. the general case}, volume = {980}, year = {2025}, }
• (2025). Primordial black holes in the solar system. ApJ, 980(2), 238. (www)

  @article{ , abstract = {If primordial black holes (PBHs) of asteroidal mass make up the entire dark matter, they could be detectable through their gravitational influence in the solar system. In this work, we study the perturbations that PBHs induce on the orbits of planets. Detailed numerical simulations of the solar system, embedded in a halo of PBHs, are performed. We find that the gravitational effect of the PBHs is dominated by the closest encounter. Using the Earth–Mars distance as an observational probe, we show that the perturbations are smaller than the current measurement uncertainties and thus PBHs are not directly constrained by solar system ephemerides. We estimate that an improvement in the ranging accuracy by an order of magnitude or the extraction of signals well below the noise level is required to detect the gravitational influence of PBHs in the solar system in the foreseeable future.}, archive = {J_ApJ}, author = {Valentin Thoss and Andreas Burkert}, doi = {10.3847/1538-4357/adae84}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {238}, shortjournal = {The Astrophys. J.}, title = {Primordial black holes in the solar system}, volume = {980}, year = {2025}, }
• (2025). Estimating the black hole spin for the X-ray binary MAXI j1727-203 based on insight-HXMT. ApJ, 980(2), 237. (www)

  @article{ , abstract = {We constrain the spin of the black hole candidate MAXI J1727-203 using Insight-HXMT data. Due to limited Insight-HXMT observations covering only part of the outburst, NICER data were used to analyze the full outburst's state transitions; we identified two of three HXMT observations in the high soft state and applied the continuum-fitting method to measure the spin. Based on previous estimates and continuum spectral fittings, we explored the parameter space and found that the best-fitting values were ( D , i , M ) ≈ (6 kpc, 30°, 12 M ⊙ ). We also tested the variation of these parameters using Monte Carlo simulations, sampling over 3000 sets within the parameter ranges 5.9 kpc < D < 7 kpc, 24° < i < 35°, and 10 M ⊙ < M < 14 M ⊙ , yielding a spin measurement of a=0.3{4}_{-0.19}^{+0.15} (1 σ ). In addition, we analyzed NuSTAR data in the low hard state and found a good fit with the tbabs∗(diskbb+powerlaw) model, with no significant iron line features observed in the residuals; therefore, the previous reflection model results suggesting an extremely high spin overestimates the black hole spin.}, archive = {J_ApJ}, author = {Haifan Zhu and Wei Wang}, doi = {10.3847/1538-4357/adae8b}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {237}, shortjournal = {The Astrophys. J.}, title = {Estimating the black hole spin for the X-ray binary MAXI j1727-203 based on insight-HXMT}, volume = {980}, year = {2025}, }
• (2025). Influence of modeling assumptions on the inferred dynamical state of resonant systems: A case study of the HD 45364 system. ApJ, 980(2), 236. (www)

  @article{ , abstract = {Planetary systems exhibiting mean motion resonances (MMRs) offer unique opportunities to study the imprint of disk-induced migration on the orbital architectures of planetary systems. The HD 45364 system, discovered via the radial velocity (RV) method to host two giant planets in a 3:2 MMR, has been the subject of several studies attempting to reconstruct the system's orbital migration history based on its present-day resonant configuration. Recently, Z. Li et al. called into question the system's residence in the 3:2 MMR based on a revised orbital solution derived from an expanded set of RV observations that extend the time baseline of the original discovery data by over a decade. However, we show that inferences about the planets' dynamical state with respect to the 3:2 MMR are sensitive to the particular prior assumptions adopted in the orbital modeling. Using N -body dynamical models, we show that orbital solutions constrained to reside deep in the 3:2 MMR fit the RV data with a similar quality to unconstrained orbital solutions. We conclude that the RV observations of HD 45364 are consistent with orbital configurations produced by smooth migration and resonance capture. We further show that past convergent orbital migration can reproduce the system's present-day orbital configuration provided that the ratio of migration to eccentricity damping timescales, K , was in the range 11 ≲ K ≲ 144. We also find that dynamical interactions in the system can break the usual mass–inclination degeneracy inherent to Keplerian models of RV observations and constrain the planets' absolute masses to within a factor of ∼1.5.}, archive = {J_ApJ}, author = {Ian Chow and Sam Hadden}, doi = {10.3847/1538-4357/adae8d}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {236}, shortjournal = {The Astrophys. J.}, title = {Influence of modeling assumptions on the inferred dynamical state of resonant systems: A case study of the HD 45364 system}, volume = {980}, year = {2025}, }
• (2025). Comparing methods for calculating solar energetic particle intensities: Rebinning versus spectral binning. ApJ, 980(2), 235. (www)

  @article{ , abstract = {Solar energetic particle (SEP) events have been observed for decades in the interplanetary medium by spacecraft measuring the intensity of energetic ions and electrons. These intensities provide valuable information about particle acceleration, the effects of bulk plasma dynamics on particle transport, and the anisotropy of particle distributions. Since measured intensities are typically reported in narrow energy bins, it is common to rebin intensities over a wider energy range to improve counting statistics. We investigate two methods for calculating intensities across multiple energy bins: (a) rebinned intensity ( {\overline{j}}_{{\rm{linlin}}} ), which is calculated by integrating the intensity over energy space and corresponds to the intensity at an effective energy that depends on the time-varying spectral index, and (b) spectral binned intensity ( {\overline{j}}_{{\rm{loglog}}} ), calculated by integrating the log intensity in log–energy space, yielding the intensity at the log-centered energy that is independent of the spectral index and remains constant over time. We compare these methods using Parker Solar Probe (PSP) IS⊙IS measurements of energetic protons, and we prescribe criteria for selecting the appropriate method for different scenarios. Our results show that the rebinned intensity is consistently larger (up to a factor of 5) than the spectral binned intensity for two SEP events observed by PSP, although the time series of the two methods are strongly correlated. Overall, both measures are important for SEP spectral analysis, and the selection of the appropriate measure depends on whether a physical (spectral binned intensity) or a statistical (rebinned intensity) representation is needed for a given analysis.}, archive = {J_ApJ}, author = {M. E. Cuesta and L. Y. Khoo and G. Livadiotis and M. M. Shen and J. R. Szalay and D. J. McComas and J. S. Rankin and R. Bandyopadhyay and H. A. Farooki and J. T. Niehof and C. M. S. Cohen and R. A. Leske and Z. Xu and E. R. Christian and M. I. Desai and M. A. Dayeh}, doi = {10.3847/1538-4357/adaea9}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {235}, shortjournal = {The Astrophys. J.}, title = {Comparing methods for calculating solar energetic particle intensities: Rebinning versus spectral binning}, volume = {980}, year = {2025}, }
• (2025). Simultaneous NICER and NuSTAR observations of the neutron star low-mass X-ray binary serpens X-1. ApJ, 980(2), 234. (www)

  @article{ , abstract = {We present the first contemporaneous NICER and NuSTAR analysis of the low-mass X-ray binary Serpens X-1 obtained in 2023 June, performing broadband X-ray spectral analysis modeling of the reprocessed emission with relxillNS from 0.4 to 30 keV. We test various continuum and background estimation models to ensure that our results do not hinge on the choice of model used, and found that the detection of reflection features is independent of the choice of both continuum and background model. The position of the inner accretion disk is consistent with the last stable circular orbit ( R in ≤ 1.2 R ISCO ) and a low inclination of i ≤ 8.3°. Additionally, we investigate the presence of the low-energy (∼1 keV) Fe L complex in the data from NICER and the Reflection Grating Spectrometer on XMM-Newton that was previously reported in the literature. We find that the line is at most a 2% feature relative to the reprocessed continuum, and are unable to claim a definitive detection for the current data set. However, we discuss plausible conditions and systems that would increase the likelihood of detecting this feature in the future.}, archive = {J_ApJ}, author = {H. Hall and R. M. Ludlam and J. M. Miller and A. C. Fabian and J. A. Tomsick and J. Coley and J. A. García and B. M. Coughenour}, doi = {10.3847/1538-4357/adaeaa}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {234}, shortjournal = {The Astrophys. J.}, title = {Simultaneous NICER and NuSTAR observations of the neutron star low-mass X-ray binary serpens X-1}, volume = {980}, year = {2025}, }
• (2025). Testing galaxy formation models with the stellar Mass–Halo mass relations for star-forming and quiescent galaxies. ApJ, 980(2), 233. (www)

  @article{ , abstract = {The tight relationship between the stellar mass and halo mass of galaxies is one of the most fundamental scaling relations in galaxy formation and evolution. It has become a critical constraint for galaxy formation models. Over the past decade, growing evidence has convincingly shown that the stellar mass–halo mass relations (SHMRs) for star-forming and quiescent central galaxies differ significantly: at a given stellar mass, the average host halo mass of quiescent centrals is more massive than that of star-forming centrals. Despite the importance of this feature, its scientific implications have not yet been fully recognized or thoroughly explored in the field. In this work, we demonstrate that the semi-analytical model L-GALAXIES successfully reproduces these observational results, whereas three state-of-the-art hydrodynamic galaxy formation simulations (TNG, Illustris, and EAGLE) do not. Consequently, in L-GALAXIES, star-forming central galaxies are more efficient at converting baryons into stars than quiescent central galaxies at a given halo mass, while the other models predict similar efficiencies for both populations. Further analysis reveals that these fundamental discrepancies stem from distinct evolutionary paths on the stellar mass–halo mass plane. We show that the observed SHMRs for star-forming and quiescent galaxies support galaxy formation models in which quenching only weakly correlates with halo assembly histories and the stellar mass of star-forming galaxies can increase significantly after cosmic noon. In contrast, models in which quenching strongly preferentially happens in early-formed halos are not very favored. Additionally, we find that galaxy downsizing is present in L-GALAXIES and TNG but absent in Illustris and EAGLE.}, archive = {J_ApJ}, author = {Kai Wang and Yingjie Peng}, doi = {10.3847/1538-4357/adaf1a}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {233}, shortjournal = {The Astrophys. J.}, title = {Testing galaxy formation models with the stellar Mass–Halo mass relations for star-forming and quiescent galaxies}, volume = {980}, year = {2025}, }
• (2025). Precession for the mode change in a gamma-ray pulsar. ApJ, 980(2), 232. (www)

  @article{ , abstract = {PSR J2021+4026 is a gamma-ray pulsar having variations in its spin-down rate and gamma-ray flux. Its variations in timing and emission are correlated, e.g., a larger spin-down rate for a low gamma-ray flux. We show that the mode change in PSR J2021+4026 can be understood in the precession scenario. In the precession model, the inclination angle is modulated due to precession. At the same time, the wobble angle may decay with time. This results in damping of the precession. Combined with the magnetospheric torque model and the outer gap model, the damped precession can explain that (1) when the inclination angle is larger, the spin-down rate will be larger, accompanied by a lower gamma-ray flux. (2) The variation in amplitude of the gamma-ray flux and spin-down rate is smaller than previous results due to the damping of the precession. The modulation period is becoming shorter due to a smaller wobble angle. In the end, we propose that there are two kinds of modulations in pulsars. Long-term modulations in pulsars may be due to precession. Short-term modulations may be of magnetospheric origin.}, archive = {J_ApJ}, author = {H. Tong and H. H. Wang}, doi = {10.3847/1538-4357/adaf1d}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {232}, shortjournal = {The Astrophys. J.}, title = {Precession for the mode change in a gamma-ray pulsar}, volume = {980}, year = {2025}, }
• (2025). Study of hybrid stars with nonstrange quark matter cores. ApJ, 980(2), 231. (www)

  @article{ , abstract = {In this work, under the hypothesis that quark matter may not be strange, we adopt a modification of the coupling constant of the four-quark scalar interaction G\to {G}_{1}+{G}_{2}\langle \bar{\psi }\psi \rangle in the two-flavor Nambu–Jona–Lasinio (NJL) model to study nonstrange hybrid stars, where G 1 and G 2 are two parameters constrained by using the lattice quantum chromodynamics simulation results at the critical temperature and zero chemical potential. The Maxwell construction is used to describe the first-order confinement–deconfinement phase transition in hybrid stars. With recent measurements on neutron star mass, radius, and tidal deformability, the hybrid equations of state are constrained. It is found that pure nonstrange quark matter cores can exist in hybrid stars, possessing 0.026–0.04 M ⊙ . The maximum hybrid star mass in the framework of the modified NJL model is about 0.1 M ⊙ lighter than that in the conventional two-flavor NJL model. It is argued that the binary neutron stars in GW170817 should be hadron stars.}, archive = {J_ApJ}, author = {Cheng-Ming Li and He-Rui Zheng and Shu-Yu Zuo and Ya-Peng Zhao and Fei Wang and Yong-Feng Huang}, doi = {10.3847/1538-4357/adaf9a}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {231}, shortjournal = {The Astrophys. J.}, title = {Study of hybrid stars with nonstrange quark matter cores}, volume = {980}, year = {2025}, }
• (2025). Three brown dwarfs masquerading as high-redshift galaxies in JWST observations. ApJ, 980(2), 230. (www)

  @article{ , abstract = {We report the spectroscopic identification of three brown dwarf candidates—o005_s41280, o006_s00089, and o006_s35616—discovered in RUBIES using James Webb Space Telescope (JWST) Near-Infrared Spectrograph PRISM/CLEAR spectroscopy. We fit these sources with multiple substellar atmosphere models and present the atmospheric parameters, including effective temperature ( T eff ), surface gravity, and other derived properties. The results suggest that o005_s41280 and o006_s35616, with T eff in the ranges of 2100–2300 K and 1800–2000 K, respectively, are likely L dwarfs, while o006_s00089, with T eff < 1000 K, is consistent with a late T dwarf classification. The best-fit model spectra provide a reasonable match to the observed spectra. However, distinct residuals exist in the Y , J , and H bands for the two L dwarf candidates, particularly for o006_s35616. Incorporating the extinction parameter into the fitting process can significantly reduce these residuals. The distance estimates indicate that these candidates are about 2 kpc away. The analysis of the color–color diagram using multiple JWST NIRcam photometry suggests that cooler T dwarfs, such as o006_s00089, overlap with little red dots, while hotter L dwarfs, like o005_s41280 and o006_s35616, tend to contaminate the high-redshift galaxy cluster. These findings suggest a brown dwarf contamination rate of approximately 0.1% in extragalactic deep field surveys, with L dwarfs being more frequently detected than cooler T and Y dwarfs.}, archive = {J_ApJ}, author = {Zhijun Tu and Shu Wang and Xiaodian Chen and Jifeng Liu}, doi = {10.3847/1538-4357/adaf9f}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {230}, shortjournal = {The Astrophys. J.}, title = {Three brown dwarfs masquerading as high-redshift galaxies in JWST observations}, volume = {980}, year = {2025}, }
• (2025). The guitar filament’s magnetic field revealed by starlight polarization. ApJ, 980(2), 229. (www)

  @article{ , abstract = {The Guitar nebula surrounding PSR B2224+65 boasts a pulsar X-ray filament likely aligned with the local magnetic field. We present new RoboPol stellar polarization data distributed along the line of sight to the pulsar. The polarizing effect of intervening magnetized dust allows us to extract a model for the dust-weighted magnetic field. We detect a magnetic field angle consistent with the filament if the pulsar is located in the more distant zone of its parallax-estimated distance range.}, archive = {J_ApJ}, author = {Jack T. Dinsmore and Roger W. Romani and Nikos Mandarakas and Dmitry Blinov and Ioannis Liodakis}, doi = {10.3847/1538-4357/adafa8}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {229}, shortjournal = {The Astrophys. J.}, title = {The guitar filament’s magnetic field revealed by starlight polarization}, volume = {980}, year = {2025}, }
• (2025). Improving the temporal resolution of SOHO/MDI magnetograms of solar active regions using a deep generative model. ApJ, 980(2), 228. (www)

  @article{ , abstract = {We present a novel deep generative model, named GenMDI, to improve the temporal resolution of line-of-sight (LOS) magnetograms of solar active regions (ARs) collected by the Michelson Doppler Imager (MDI) on board the Solar and Heliospheric Observatory. Unlike previous studies that focus primarily on spatial super-resolution of MDI magnetograms, our approach can perform temporal super-resolution, which generates and inserts synthetic data between observed MDI magnetograms, thus providing finer temporal structure and enhanced details in the LOS data. The GenMDI model employs a conditional diffusion process, which synthesizes images by considering both preceding and subsequent magnetograms, ensuring that the generated images are not only of high quality but also temporally coherent with the surrounding data. Experimental results show that the GenMDI model performs better than the traditional linear interpolation method, especially in ARs with dynamic evolution in magnetic fields.}, archive = {J_ApJ}, author = {Jialiang Li and Vasyl Yurchyshyn and Jason T. L. Wang and Haimin Wang and Yasser Abduallah and Khalid A. Alobaid and Chunhui Xu and Ruizhu Chen and Yan Xu}, doi = {10.3847/1538-4357/adb032}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {228}, shortjournal = {The Astrophys. J.}, title = {Improving the temporal resolution of SOHO/MDI magnetograms of solar active regions using a deep generative model}, volume = {980}, year = {2025}, }
• (2025). Periodic variability of the central stars of planetary nebulae surveyed through the zwicky transient facility. ApJ, 980(2), 227. (www)

  @article{ , abstract = {A consensus has been reached in recent years that binarity plays an important role in the formation and evolution of a significant fraction of planetary nebulae (PNe). Utilizing the archived photometric data from the Zwicky Transient Facility survey, we conducted a comprehensive data mining in search of brightness variations in a large sample of Galactic PNe. This effort led to identification of 39 PNe, whose central stars exhibit periodic variation in light curves. Among these objects, 20 are known binary central stars of PNe, while the remaining 19 are new discoveries. Additionally, we identified 14 PNe with central stars displaying anomalous variation in light curves, as well as eight variables based on the high-cadence photometric data. Among the new discoveries of periodicity, we found compelling evidence of binary systems at the centers of two archetypal quadrupolar PNe. We also report on very peculiar brightness variation observed in the central core of the compact PN NGC 6833. Several PNe in our sample deserve follow-up observations, both high-dispersion spectroscopy and high-precision photometry, to reveal the true nature of their central binarity or even multiplicity.}, archive = {J_ApJ}, author = {Pinjian Chen and Xuan Fang and Xiaodian Chen and Jifeng Liu}, doi = {10.3847/1538-4357/ada94a}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {227}, shortjournal = {The Astrophys. J.}, title = {Periodic variability of the central stars of planetary nebulae surveyed through the zwicky transient facility}, volume = {980}, year = {2025}, }
• (2025). Geometric correction for wind accretion in binary systems. ApJ, 980(2), 226. (www)

  @article{ , abstract = {The Bondi–Hoyle–Lyttleton (BHL) accretion model is widely used to describe how a compact object accretes material from a companion's stellar wind in binary systems. However, its standard implementation becomes inaccurate when the wind velocity ( v w ) is comparable to or less than the orbital velocity ( v o ), predicting nonphysical accretion efficiencies above unity. This limits its applicability to systems with low wind-to-orbital velocity ratios ( w = v w / v o ≤ 1), such as symbiotic systems. We revisit the implementation of the BHL model and introduce a geometric correction factor that accounts for the varying orientation of the accretion cylinder relative to the wind direction. This correction ensures physically plausible accretion efficiencies ( η ≤ 1) for all w in circular orbits. Our new implementation naturally predicts the flattening of the accretion efficiency observed in numerical simulations for w < 1, without the need for ad hoc adjustments. We also peer into the implications of our prescription for the less-explored case of eccentric orbits, highlighting the key role of the geometric correction factor in shaping the accretion process. We compare our predictions with numerical simulations, finding good agreement for a wide range of parameters. Applications to the symbiotic star R Aqr and the X-ray binary LS 5039 are presented. This improved implementation offers a more accurate description of wind accretion in binary systems, with implications for stellar evolution, population synthesis, and observational data interpretation.}, archive = {J_ApJ}, author = {Emilio Tejeda and Jesús A. Toalá}, doi = {10.3847/1538-4357/ada953}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {226}, shortjournal = {The Astrophys. J.}, title = {Geometric correction for wind accretion in binary systems}, volume = {980}, year = {2025}, }
• (2025). Deep rest-UV JWST/NIRSpec spectroscopy of early galaxies: The demographics of c iv and N-emitters in the reionization era. ApJ, 980(2), 225. (www)

  @article{ , abstract = {JWST has recently discovered a subset of reionization era galaxies with ionized gas that is metal-poor in oxygen and carbon but heavily enriched in nitrogen. This abundance pattern is almost never seen in lower-redshift galaxies but is commonly observed in globular cluster stars. We have recently demonstrated that this peculiar abundance pattern appears in a compact (≃20 pc) metal-poor galaxy undergoing a strong burst of star formation. This galaxy was originally selected based on strong C iv emission, indicating a hard radiation field rarely seen locally. In this paper, we present JWST/NIRSpec observations of another reionization-era galaxy known to power strong C iv emission, the z = 7.04 gravitationally lensed galaxy A1703-zd6. The emission-line spectrum reveals this is a metal-poor galaxy ( 12+\mathrm{log}({\rm{O}}/{\rm{H}})=7.47\pm 0.19 ) dominated by a young stellar population ( 1.{6}_{-0.4}^{+0.5} Myr) that powers a very hard ionizing spectrum (C iv equivalent width, EW = 19.4 Å, He ii EW = 2.2 Å). The interstellar medium is highly enriched in nitrogen ( \mathrm{log}({\rm{N}}/{\rm{O}})=-0.6 ) with very high electron densities (8–19 × 10 4 cm −3 ) and extreme ionization conditions rarely seen at lower redshift. We also find intense CIV emission (EW ≳ 20 Å) in two new z ≳ 6 metal-poor galaxies. To put these results in context, we search for UV line emission in a sample of 737 z ≳ 4 galaxies with NIRSpec spectra, establishing that 40%(30%) of systems with [O iii ]+H β EW  >  2000 Å have N iv ] (C iv ) detections with EW >  5 Å(>  10 Å). These results suggest high N/O ratios, and hard ionizing sources appear in a brief phase following a burst of star formation in compact high-density stellar complexes.}, archive = {J_ApJ}, author = {Michael W. Topping and Daniel P. Stark and Peter Senchyna and Zuyi Chen and Adi Zitrin and Ryan Endsley and Stéphane Charlot and Lukas J. Furtak and Michael V. Maseda and Adele Plat and Renske Smit and Ramesh Mainali and Jacopo Chevallard and Stephen Molyneux and Jane R. Rigby}, doi = {10.3847/1538-4357/ada95c}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {225}, shortjournal = {The Astrophys. J.}, title = {Deep rest-UV JWST/NIRSpec spectroscopy of early galaxies: The demographics of c iv and N-emitters in the reionization era}, volume = {980}, year = {2025}, }
• (2025). Exploring mass transfer mechanisms in symbiotic systems. ApJ, 980(2), 224. (www)

  @article{ , abstract = {We define two regimes of the parameter space of symbiotic systems based on the dominant mass transfer mechanism. A wide range of white dwarf (WD) mass, donor mass, and donor radius combinations are explored to determine the separation for each parameter combination, below which wind Roche-lobe (RL) overflow will be the dominant mass transfer mechanism. The underlying concept is the premise that the wind accelerates. If it reaches the RL before attaining sufficient velocity to escape, it will be trapped and gravitationally focused through the inner Lagrangian point toward the accreting WD. However, if the wind succeeds in attaining the required velocity to escape from the donor's RL, it will disperse isotropically, and the dominant mass transfer mechanism will be the Bondi–Hoyle–Lyttleton prescription, in which only a fraction of the wind will be accreted onto the WD. We present these two regimes of the 4D parameter space, covering 375 different parameter combinations.}, archive = {J_ApJ}, author = {Irin Babu Vathachira and Yael Hillman and Amit Kashi}, doi = {10.3847/1538-4357/adabca}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {224}, shortjournal = {The Astrophys. J.}, title = {Exploring mass transfer mechanisms in symbiotic systems}, volume = {980}, year = {2025}, }
• (2025). A pilot study for the CSST slitless spectroscopic quasar survey based on mock data. ApJ, 980(2), 223. (www)

  @article{ , abstract = {The wide survey of the Chinese Space Station Telescope (CSST) will observe a large field of 17,500 deg 2 . The GU, GV, and GI grism observations of CSST will cover the wavelength range from 2550 to 10000 Å at a resolution of R ∼ 200 and a depth of about 22 AB magnitude for the continuum. In this paper, we present a pipeline to identify quasars and measure their physical properties with the CSST mock data. We simulate the raw images and extract the one-dimensional grism spectra for quasars, galaxies, and stars with r -band magnitudes of 18 < m r < 22 using the CSST Cycle 6 simulation code ( https://csst-tb.bao.ac.cn/code/csst_sim/csst-simulation ). Using a convolution neural network, we separate quasars from stars and galaxies. We measure the redshifts by identifying strong emission lines of quasars. We also fit the 1D slitless spectra with QSOFITMORE to estimate black hole masses and Eddington ratios. Our results show that CSST slitless spectroscopy can effectively separate quasars with redshifts z = 0−5 from other types of objects with an accuracy of 99%. Among those successfully classified quasars, 90% of them could have precise redshift measurements with σ NMAD = 0.002. The scatters of black hole masses and Eddington ratios from the spectral fittings are 0.13 and 0.15 dex, respectively. The metallicity diagnosis line ratios have a scatter of 0.1–0.2 dex. Our results show that the CSST slitless spectroscopy survey has the potential to discover about 0.9 million new quasars and provide important contributions to the science of active galactic nuclei and cosmology.}, archive = {J_ApJ}, author = {Yuxuan Pang and Xue-Bing Wu and Yuming Fu and Rui Zhu and Bing Lyu and Huimei Wang and Xiaotong Feng}, doi = {10.3847/1538-4357/adabdc}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {223}, shortjournal = {The Astrophys. J.}, title = {A pilot study for the CSST slitless spectroscopic quasar survey based on mock data}, volume = {980}, year = {2025}, }
• (2025). Alfvén wave conversion to low frequency fast magnetosonic waves in magnetar magnetospheres. ApJ, 980(2), 222. (www)

  @article{ , abstract = {Rapid shear motion of magnetar crust can launch Alfvén waves into the magnetosphere. The dissipation of the Alfvén waves has been theorized to power the X-ray bursts characteristic of magnetars. However, the process by which Alfvén waves convert their energy to X-rays is unclear. Recent work has suggested that energetic fast magnetosonic (fast) waves can be produced as a byproduct of Alfvén waves propagating on curved magnetic field lines; their subsequent dissipation may power X-ray bursts. In this work, we investigate the production of fast waves by performing axisymmetric force-free simulations of Alfvén waves propagating in a dipolar magnetosphere. For Alfvén wave trains that do not completely fill the flux tube confining them, we find a fast wave dominated by a low frequency component with a wavelength defined by the bouncing time of the Alfvén waves. In contrast, when the wave train is long enough to completely fill the flux tube, and the Alfvén waves overlap significantly, the energy is quickly converted into a fast wave with a higher frequency that corresponds to twice the Alfvén wave frequency. We investigate how the energy, duration, and wavelength of the initial Alfvén wave train affect the conversion efficiency to fast waves. For modestly energetic star quakes, we see that the fast waves that are produced will become nonlinear well within the magnetosphere, and we comment on the X-ray emission that one may expect from such events.}, archive = {J_ApJ}, author = {Dominic Bernardi and Yajie Yuan and Alexander Y. Chen}, doi = {10.3847/1538-4357/adabe5}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {222}, shortjournal = {The Astrophys. J.}, title = {Alfvén wave conversion to low frequency fast magnetosonic waves in magnetar magnetospheres}, volume = {980}, year = {2025}, }
• (2025). Impacts of UV radiation from an AGN on planetary atmospheres and consequences for galactic habitability. ApJ, 980(2), 221. (www)

  @article{ , abstract = {We present a study of the effects of ultraviolet (UV) emission from active galactic nuclei (AGN) on the atmospheric composition of planets and potential impact on life. It is expected that all supermassive black holes, which reside at galactic centers, have gone through periods of high AGN activity in order to reach their current masses. We examine potential damaging effects on lifeforms on planets with different atmosphere types and receiving different levels of AGN flux, using data on the sensitivity of various species' cells to UV radiation to determine when radiation becomes "dangerous." We also consider potential chemical changes to planetary atmospheres as a result of UV radiation from AGN, using the Platform for Atmosphere, Land, Earth, and Ocean photochemical model. We find that the presence of sufficient initial oxygen (surface mixing ratio ≥10 −3 mol mol −1 ) in the planet's atmosphere allows a thicker ozone layer to form in response to AGN radiation, which reduces the level of dangerous UV radiation incident on the planetary surface from what it was in absence of an AGN. We estimate the fraction of solar systems in galaxies that would be affected by substantial AGN UV radiation, and find that the impact is most pronounced in compact galaxies such as "red nugget relics," as compared to typical present-day ellipticals and spirals (using M87 and the Milky Way as examples).}, archive = {J_ApJ}, author = {Kendall I. Sippy and Jake K. Eager-Nash and Ryan C. Hickox and Nathan J. Mayne and McKinley C. Brumback}, doi = {10.3847/1538-4357/adac5d}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {221}, shortjournal = {The Astrophys. J.}, title = {Impacts of UV radiation from an AGN on planetary atmospheres and consequences for galactic habitability}, volume = {980}, year = {2025}, }
• (2025). Constraining the nuclear equation of state of a neutron star via high-frequency quasi-periodic oscillation in short gamma-ray bursts. ApJ, 980(2), 220. (www)

  @article{ , abstract = {The determination of the equation of state (EOS) of a neutron star (NS) and its maximum mass is very important for understanding the formation and properties of NSs under extreme conditions, but they remain open questions. Short-duration gamma-ray bursts (GRBs) are believed to originate from the merger of binary NSs or giant flares (GFs) of soft gamma repeaters (SGRs). Recently, the high-frequency quasi-periodic oscillations (QPOs) have been claimed to be identified from two short GRBs (GRB 931101B and GRB 910711). In this paper, we propose that the observed high-frequency QPOs in these two short GRBs result from torsional oscillations in the GFs of SGRs associated with cold NSs, or from radial oscillations of hypermassive NSs as the hot remnants of binary NS mergers, and then to constrain the EOS of NSs. For torsional oscillations, the six selected EOSs (TM1, NL3, APR, SLy4, DDME2, and GM1) of NSs suitable for the zero-temperature condition exhibit significant overlap in mass ranges, suggesting that we cannot constrain the EOS of NSs. For radial oscillations, the six selected EOSs (IUF, TM1, TMA, FSG, BHBLp, and NL3) of NSs suitable for the high-temperature condition cannot be ruled out when redshift is considered. However, it is found that the EOS can only be constrained if the redshift and temperature of the remnant can be measured.}, archive = {J_ApJ}, author = {Jun-Xiang Huang and Hou-Jun Lü and En-Wei Liang}, doi = {10.3847/1538-4357/adaceb}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {220}, shortjournal = {The Astrophys. J.}, title = {Constraining the nuclear equation of state of a neutron star via high-frequency quasi-periodic oscillation in short gamma-ray bursts}, volume = {980}, year = {2025}, }
• (2025). The bolometric light-curve modeling of 98 type i superluminous supernovae using the magnetar- and the circumstellar interaction models reveals surprisingly high ejecta masses. ApJ, 980(2), 219. (www)

  @article{ , abstract = {We present the bolometric light-curve modeling of 98 hydrogen-poor superluminous supernovae (SLSNe-I) using three types of power inputs: the magnetar model and two kinds of circumstellar interaction models, applying the constant density and the steady wind scenario. The quasi-bolometric luminosities of the objects were calculated from the Zwicky Transient Facility g - and r -band data using the methodology of Chen et al., and then they were modeled with the Minim code. It was found that the light curves of 45 SLSNe-I can be fitted equally well with both the magnetar and the circumstellar material (CSM) models, 14 objects prefer the magnetar model, and 39 SLSNe-I favor the CSM model. The magnetar modeling yielded a mean spin period of P = 4.1 ± 0.20 ms and a magnetic field of B = 5.65 ± 0.43 · 10 14 G, consistent with the literature. However, the ejected mass was estimated to be significantly larger compared to previous studies presenting either multicolor light-curve modeling with MOSFiT or bolometric light-curve modeling: we obtained a mean value and standard error of 34.26 and 4.67 M ⊙ , respectively. The circumstellar interaction models resulted in even larger ejecta masses with a mean and standard error of 116.82 and 5.97 M ⊙ for the constant density model, and 105.99 and 4.50 M ⊙ for the steady wind model. Although the ejected mass depends strongly on the electron scattering opacity (assumed to be κ = 0.2 in this work) and the ejecta velocity, which were estimated to be globally larger compared to earlier studies, our results suggest that SLSNe-I are indeed explosions of the most-massive stars.}, archive = {J_ApJ}, author = {Réka Könyves-Tóth}, doi = {10.3847/1538-4357/adae04}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {219}, shortjournal = {The Astrophys. J.}, title = {The bolometric light-curve modeling of 98 type i superluminous supernovae using the magnetar- and the circumstellar interaction models reveals surprisingly high ejecta masses}, volume = {980}, year = {2025}, }
• (2025). Dependence of multiband absolute magnitudes and color indexes of the tip of the red giant branch stars on metallicity in galactic globular clusters. ApJ, 980(2), 218. (www)

  @article{ , abstract = {The tip of the red giant branch (TRGB) stars have attracted intensive attention in recent years because their I -band absolute magnitudes, M I , are often used for distance calibration in the Hubble constant measurements because of its almost independence on metallicity ([Fe/H]). However, a discrepancy exists between various studies, and the theoretical stellar model predicts the dependence of their luminosity on [Fe/H]. Here, we present a careful study of the dependence of absolute magnitudes and color indexes on metallicity in optical and near-infrared bands. With the TRGB stars identified in 33 Galactic globular clusters by the reddest color in the G BP − G RP versus G RP diagram, it is confirmed that M I is almost constant of  −4.017 ± 0.036 ± 0.027 mag when [Fe/H] < −1.2, which would give H 0 = 70.86 ± 1.2 ± 0.9 km s −1 Mpc −1 with this updated luminosity calibration for Type Ia supernovae. However, for [Fe/H] > −1.2, M I is found to become fainter with lower metallicity, which would lead to a larger Hubble constant. In the optical G BP , G RP , and V bands, the absolute magnitude of TRGB stars tends to increase with metallicity, while in the infrared J , H , and K s bands, the variation with metallicity shows an inverse tendency. In addition, the analytical relations of the color indexes with metallicity are presented, which have smaller dispersion than those derived for the corresponding absolute magnitudes.}, archive = {J_ApJ}, author = {Zhenzhen Shao and Shu Wang and Biwei Jiang and Xiaofeng Wang and Zhishuai Ge and Haichang Zhu}, doi = {10.3847/1538-4357/adae8e}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {218}, shortjournal = {The Astrophys. J.}, title = {Dependence of multiband absolute magnitudes and color indexes of the tip of the red giant branch stars on metallicity in galactic globular clusters}, volume = {980}, year = {2025}, }
• (2025). Asteroseismology with TESS: Emergence of dipole mode suppression from subgiants?. ApJ, 980(2), 217. (www)

  @article{ , abstract = {Dipole mode suppression is an observed behavior of solar-like oscillations in evolved stars. This study aims to search for depressed dipole modes in giant stars using data from the Transiting Exoplanet Survey Satellite (TESS) and investigate when the suppression starts to emerge. We study a sample of 8651 evolved stars from TESS and find 179 stars with significant dipole mode depression by comparing the oscillation amplitudes of radial and dipole modes. Notably, 11 of them are located near the base of the red giant branch, indicating that mode suppression appears earlier than the point inferred in previous studies with Kepler data. These findings provide new evidence for dipole mode suppression in giant stars, particularly in subgiants.}, archive = {J_ApJ}, author = {Shurui Lin and Tanda Li and Shude Mao and Jim Fuller}, doi = {10.3847/1538-4357/adae9e}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {217}, shortjournal = {The Astrophys. J.}, title = {Asteroseismology with TESS: Emergence of dipole mode suppression from subgiants?}, volume = {980}, year = {2025}, }
• (2025). Measuring star formation rates in the milky way from hi-GAL 70 μm observations. ApJ, 980(2), 216. (www)

  @article{ , abstract = {Three methods for computing the total star formation rate (SFR) of the Milky Way agree well with a reference value of 1.65 ± 0.19 M ⊙ yr −1 . They are then used to determine the radial dependence of the SFR and face-on map for the Milky Way. First, the method based on a model of star formation in Hi-GAL-defined dense clumps, adjusted for an increase in the gas-to-dust ratio with Galactocentric radius, predicts 1.65 ± 0.61 M ⊙ yr −1 . Second, the method using the 70 μ m emission, commonly used in other galaxies, with a technique to assign distances to the extended emission, predicts 1.4{2}_{-0.44}^{+0.63} M ⊙ yr −1 . Finally, a method based on theoretical predictions of star formation efficiency as a function of virial parameter, with masses corrected for metallicity dependence, applied to a catalog of molecular clouds also predicts a value in agreement at 1.47 M ⊙ yr −1 . The three methods predict the radial variation of the SFR, with remarkably good agreement from the Central Molecular Zone out to about 20 kpc. More differences were seen in face-on maps with a resolution of 0.5 kpc made with the three approaches and in comparisons to the local (within 3 kpc) SFR, indicating limitations of the methods when applied to smaller scales. The 70 μ m SFR follows very closely the surface density of molecular gas, corrected for a metallicity-dependent CO conversion factor. A molecular gas depletion time of 1 Gyr is consistent with the data, as is a molecular Kennicutt–Schmidt relation with a power-law slope of 1.10 ± 0.06.}, archive = {J_ApJ}, author = {Davide Elia and Neal J. Evans and Juan D. Soler and Francesco Strafella and Eugenio Schisano and Sergio Molinari and Andrea Giannetti and Sudeshna Patra}, doi = {10.3847/1538-4357/adaeb2}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {216}, shortjournal = {The Astrophys. J.}, title = {Measuring star formation rates in the milky way from hi-GAL 70 μm observations}, volume = {980}, year = {2025}, }
• (2025). The morphology of dwarf galaxies hosting variable active galactic nuclei. ApJ, 980(2), 215. (www)

  @article{ , abstract = {We analyze Hubble Space Telescope optical imaging of eight low-mass galaxies hosting active galactic nuclei (AGN) identified via their photometric variability in V. F. Baldassare et al. We use GALFIT to model the 2D galaxy light profiles, and find a diversity of morphologies. The galaxies with regular morphologies are best fit with pseudobulges and disks, rather than classical bulges. We estimate black hole masses using scaling relations and find black hole masses of 10 3.7−6.6 M ⊙ . We compare this sample to dwarf galaxies with AGN selected via optical spectroscopy. On average, the variable host galaxies have lower-mass black holes. We analyze the brightest point source in each galaxy and find their properties are not entirely consistent with star clusters, indicating that they are likely AGN. These point sources are found to have lower luminosities than spectroscopically selected dwarf AGN, but brighter than the point sources in dwarf galaxies not identified as AGN. Our detailed imaging analysis shows that variability selection has the potential to find lower-mass black holes and lower-luminosity AGN than optical spectroscopy. These active dwarfs may have been missed by spectroscopic searches due to star formation dilution or low gas content.}, archive = {J_ApJ}, author = {Erin Kimbro and Vivienne Baldassare and Guy Worthey and Marla Geha and Jenny Greene}, doi = {10.3847/1538-4357/adaebf}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {215}, shortjournal = {The Astrophys. J.}, title = {The morphology of dwarf galaxies hosting variable active galactic nuclei}, volume = {980}, year = {2025}, }
• (2025). Multiband polarization profile analysis of three-component radio pulsars by implementing a relativistic phase-shift method. ApJ, 980(2), 214. (www)

  @article{ , abstract = {In this paper, we show the estimation of the emission altitude of pulsars PSRs B0329+54, B0450-18, B2045-16, J1909+0007, and J0337+1715 for both core and conal components at multiple radio bands by implementing a relativistic phase-shift method, which is constrained based on the plethora of standard radio emission geometry. Using the information of pulse longitudes for each component, coupled with a dipolar field geometry, we obtain a rough estimation of the height and transverse location of the emitting cones for these pulsars, i.e., footpoint location of the pulse edge, normalized with the last open magnetic field line constant. We also analyzed the profile of a well-known millisecond pulsar J0337+1715 at 1250 MHz, which has an asymmetric core-cone structure for both the main pulse and interpulse. This is the first time such a case has been analyzed to probe emission height by implementing the relativistic phase-shift method. We discuss the implications of our findings in the context of the pulsar's emission geometry to reach a consensus on the existing emission mechanism of pulsars.}, archive = {J_ApJ}, author = {Tridib Roy and Mayuresh Surnis and Ramkrishna Das}, doi = {10.3847/1538-4357/ada565}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {214}, shortjournal = {The Astrophys. J.}, title = {Multiband polarization profile analysis of three-component radio pulsars by implementing a relativistic phase-shift method}, volume = {980}, year = {2025}, }
• (2025). Hunting for candidates of changing-look blazars using mclust clustering analysis. ApJ, 980(2), 213. (www)

  @article{ , abstract = {C​​hanging-look blazars (CLBs) are blazars whose optical spectral lines at different epochs show significant changes and present a clear transition between standard FSRQ and BL Lacertae (BL Lac). Changing-look phenomena in blazars are highly significant for enhancing our understanding of certain physical problems of active galactic nuclei (AGNs), such as the potential mechanism of state transition in the accretion process of supermassive black holes in the central engine of AGNs, the possible intrinsic variation of the jet, and the connection between the accretion disk and the jet. Currently, the CLBs reported in the literature are still rare astronomical objects. In our previous work, we found that there are eight physical property parameters of CLBs located between those of FSRQs and BL Lacs. In order to search for more CLB candidates (CLBCs), we employed the mclust Gaussian mixture modeling clustering algorithm to perform clustering analysis for 255 subsets of the eight physical property parameters with 2250 blazars from 4FGL data release 3. We find that there are 29 subsets with three groups (corresponding to bl lacs, fsrqs, and CLBCs), in which there are four subsets with an adjusted Rand index greater than 0.610. The combined clustering results from the four subsets report that there are 111 CLBCs, which include 44 CLBs reported in previous literature and 67 new CLBCs, of which 11 are labeled as BL Lacs and 56 are labeled as FSRQs in the 4FGL catalog.}, archive = {J_ApJ}, author = {Shi-Ju Kang and Shan-Shan Ren and Yong-Gang Zheng and Qingwen Wu}, doi = {10.3847/1538-4357/ada7ec}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {213}, shortjournal = {The Astrophys. J.}, title = {Hunting for candidates of changing-look blazars using mclust clustering analysis}, volume = {980}, year = {2025}, }
• (2025). Bridging the gap: GRB 230812B—A 3 s supernova-associated burst detected by the GRID mission. ApJ, 980(2), 212. (www)

  @article{ , abstract = {GRB 230812B, detected by the Gamma-Ray Integrated Detectors constellation mission, is an exceptionally bright gamma-ray burst (GRB) with a duration of only 3 s. Sitting near the traditional boundary (∼2 s) between long and short GRBs, GRB 230812B is notably associated with a supernova, indicating a massive star progenitor. This makes it a rare example of a short-duration GRB resulting from stellar collapse. Our analysis, using a time-evolving synchrotron model, suggests that the burst has an emission radius of approximately 10 14.5 cm. We propose that the short duration of GRB 230812B is due to the combined effects of the central engine's activity time and the time required for the jet to break through the stellar envelope. Our findings provide another case that challenges the conventional view that short-duration GRBs originate exclusively from compact object mergers, demonstrating that a broader range of durations exists for GRBs arising from the collapse of massive stars.}, archive = {J_ApJ}, author = {Chen-Yu Wang and Yi-Han Iris Yin and Bin-Bin Zhang and Hua Feng and Ming Zeng and Shao-Lin Xiong and Xiao-Fan Pan and Jun Yang and Yan-Qiu Zhang and Chen Li and Zhen-Yu Yan and Chen-Wei Wang and Xu-Tao Zheng and Jia-Cong Liu and Qi-Dong Wang and Zi-Rui Yang and Long-Hao Li and Qi-Ze Liu and Zheng-Yang Zhao and Bo Hu and Yi-Qi Liu and Si-Yuan Lu and Zi-You Luo and Ji-Rong Cang and De-Zhi Cao and Wen-Tao Han and Li-Ping Jia and Xing-Yu Pan and Yang Tian and Ben-Da Xu and Xiao Yang and Zhi Zeng and GRID Collaboration}, doi = {10.3847/1538-4357/ada934}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {212}, shortjournal = {The Astrophys. J.}, title = {Bridging the gap: GRB 230812B—A 3 s supernova-associated burst detected by the GRID mission}, volume = {980}, year = {2025}, }
• (2025). Extragalactic magnetar giant flares: Population implications, rates, and prospects for gamma-rays, gravitational waves, and neutrinos. ApJ, 980(2), 211. (www)

  @article{ , abstract = {Magnetar giant flares (MGFs) are the most energetic non-catastrophic transients known to originate from stellar objects. The first discovered events were nearby. In recent years, several extragalactic events have been identified, implying an extremely high volumetric rate. We show that future instruments with a sensitivity  ≲5 × 10 −9 erg cm −2 at ∼1 MeV will be dominated by extragalactic MGFs over short gamma-ray bursts (sGRBs). Clear discrimination of MGFs requires intrinsic GRB localization capability to identify host galaxies. As MGFs involve a release of a sizable fraction of the neutron star's magnetic free energy reservoir in a single event, they provide us with invaluable tools for better understanding magnetar birth properties and the evolution of their magnetic fields. A major obstacle is to identify a (currently) small subpopulation of MGFs in a larger sample of more energetic and distant sGRBs. We develop the tools to analyze the properties of detected events and their occurrence rate relative to sGRBs. Even with the current (limited) number of events, we can constrain the initial internal magnetic field of a typical magnetar at formation to be B 0 ≈ 4 × 10 14 –2 × 10 15 G. Larger samples will constrain the distribution of birth fields. We also estimate the contribution of MGFs to the gravitational-wave (GW) stochastic background. Depending on the acceleration time of baryon-loaded ejecta involved in MGFs, their GW emission may reach beyond 10 kHz and, if so, will likely dominate over other conventional astrophysical sources in that frequency range.}, archive = {J_ApJ}, author = {Paz Beniamini and Zorawar Wadiasingh and Aaron Trigg and Cecilia Chirenti and Eric Burns and George Younes and Michela Negro and Jonathan Granot}, doi = {10.3847/1538-4357/ada947}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {211}, shortjournal = {The Astrophys. J.}, title = {Extragalactic magnetar giant flares: Population implications, rates, and prospects for gamma-rays, gravitational waves, and neutrinos}, volume = {980}, year = {2025}, }
• (2025). Self-consistent solutions of evolving nuclear star clusters with two-dimensional monte carlo dynamical simulations. ApJ, 980(2), 210. (www)

  @article{ , abstract = {We recently developed a Monte Carlo method ( GNC ) that can simulate the dynamical evolution of a nuclear star cluster (NSC) with a massive black hole (MBH), where the two-body relaxations can be solved by the Fokker–Planck equations in energy and angular momentum space. Here we make a major update of GNC by integrating stellar potential and adiabatic invariant theory, so that we can study the self-consistent dynamics of NSCs with increasing mass of the MBH. We perform tests of the self-adaptation of cluster density due to MBH mass growth and Plummer core collapse, both finding consistent results with previous studies, the latter having a core collapse time of ∼17 t rh by GNC , where t rh is the time of half-mass relaxation. We use GNC to study the cosmological evolution of the properties of NSCs and the mass of MBHs assuming that the mass growth of the MBH is due to loss-cone accretion of stars (e.g., tidal disruption of stars) and stellar black holes, and we compare the simulation results with the observations of NSCs in the Milky Way or nearby galaxies. It is possible for such a scenario to produce MBHs with mass 10 5 –10 7 M ⊙ for NSCs with stellar mass of 10 6 –10 9 M ⊙ . In the Milky Way's NSC, to grow an MBH up to 4 × 10 6 M ⊙ , its size needs to be ∼1.7 times more compact in early Universe than the current value. MBHs with current masses >6 × 10 7 M ⊙ seem difficult to explain by loss-cone accretion alone, and thus they may require other additional accretion channels, such as gas accretion.}, archive = {J_ApJ}, author = {Fupeng Zhang and Pau Amaro Seoane}, doi = {10.3847/1538-4357/adaa7a}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {210}, shortjournal = {The Astrophys. J.}, title = {Self-consistent solutions of evolving nuclear star clusters with two-dimensional monte carlo dynamical simulations}, volume = {980}, year = {2025}, }
• (2025). Universal constants in self-organized criticality systems. ApJ, 980(2), 209. (www)

  @article{ , abstract = {The occurrence frequency distributions of fluxes ( F ) and fluences or energies ( E ) observed in the majority (in 18 out of 23 cases) of astrophysical phenomena are found to be consistent with the predictions of the fractal-diffusive self-organized criticality (FD-SOC) model, which predicts power-law slopes with universal constants of α F = (9/5) = 1.80 for the flux and α E = (5/3) ≈ 1.67 for the fluence. The theoretical FD-SOC model is based on the fractal dimension, the flux-volume proportionality, and classical diffusion. The universal scaling laws predict the size distributions of numerous astrophysical phenomena, such as solar flares, stellar flares, coronal mass ejections, auroras, blazars, active galactic nuclei, black hole systems, galactic fast radio bursts, gamma-ray bursts, and soft gamma-ray repeaters. In contrast, we identify five outliers of astrophysical phenomena, i.e., coherent solar radio bursts, random solar radio bursts, solar energetic particles, cosmic rays, and pulsar glitches, which are not consistent with the standard FD-SOC model, and thus require different physical mechanisms.}, archive = {J_ApJ}, author = {Markus J. Aschwanden}, doi = {10.3847/1538-4357/adae0c}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {209}, shortjournal = {The Astrophys. J.}, title = {Universal constants in self-organized criticality systems}, volume = {980}, year = {2025}, }
• (2025). Unraveling the nature of HAWC j1844–034 with fermi-LAT data analysis and multiwavelength modeling. ApJ, 980(2), 208. (www)

  @article{ , abstract = {The extended ultra-high-energy (UHE) gamma-ray source HAWC J1844–034 is closely associated with two other sources, HAWC J1843–032 and HWC J1846–025. Moreover, other gamma-ray observatories like HESS, LHAASO, and Tibet AS γ have detected UHE gamma-ray sources whose spatial positions coincide with the position of HAWC J1844–034. The UHE gamma-ray data from several observatories aid analysis of the spectral features of this source in detail at teraelectronvolt energies. Of the four pulsars near HAWC J1844–034, PSR J1844–0346 is closest to it and possibly supplies the cosmic-ray leptons to power this source. We have analyzed the Fermi–Large Area Telescope (LAT) data to explore this source's morphology and identify its spectral features in the Fermi-LAT energy band. After removing the contribution of the pulsar to the gamma-ray spectral energy distribution (SED) by pulsar-phased analysis, we obtained upper limits on the photon flux and identified the gigaelectronvolt counterpart PS J1844.2–0342 in the Fermi-LAT energy band with more than 5 σ significance, which may be a pulsar wind nebula (PWN). Finally, the multiwavelength SED is modeled, assuming HAWC J1844–034 is a PWN.}, archive = {J_ApJ}, author = {Sovan Boxi and Saptarshi Ghosh and Nayantara Gupta}, doi = {10.3847/1538-4357/adae0e}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {208}, shortjournal = {The Astrophys. J.}, title = {Unraveling the nature of HAWC j1844–034 with fermi-LAT data analysis and multiwavelength modeling}, volume = {980}, year = {2025}, }
• (2025). Swift-BAT GUANO follow-up of gravitational-wave triggers in the third LIGO–Virgo–KAGRA observing run. ApJ, 980(2), 207. (www)

  @article{ , abstract = {We present results from a search for X-ray/gamma-ray counterparts of gravitational-wave (GW) candidates from the third observing run (O3) of the LIGO–Virgo–KAGRA network using the Swift Burst Alert Telescope (Swift-BAT). The search includes 636 GW candidates received with low latency, 86 of which have been confirmed by the offline analysis and included in the third cumulative Gravitational-Wave Transient Catalogs (GWTC-3). Targeted searches were carried out on the entire GW sample using the maximum-likelihood Non-imaging Transient Reconstruction and Temporal Search pipeline on the BAT data made available via the GUANO infrastructure. We do not detect any significant electromagnetic emission that is temporally and spatially coincident with any of the GW candidates. We report flux upper limits in the 15–350 keV band as a function of sky position for all the catalog candidates. For GW candidates where the Swift-BAT false alarm rate is less than 10 −3 Hz, we compute the GW–BAT joint false alarm rate. Finally, the derived Swift-BAT upper limits are used to infer constraints on the putative electromagnetic emission associated with binary black hole mergers.}, archive = {J_ApJ}, author = {Gayathri Raman and Samuele Ronchini and James Delaunay and Aaron Tohuvavohu and Jamie A. Kennea and Tyler Parsotan and Elena Ambrosi and Maria Grazia Bernardini and Sergio Campana and Giancarlo Cusumano and Antonino D’Aì and Paolo D’Avanzo and Valerio D’Elia and Massimiliano De Pasquale and Simone Dichiara and Phil Evans and Dieter Hartmann and Paul Kuin and Andrea Melandri and Paul O’Brien and Julian P. Osborne and Kim Page and David M. Palmer and Boris Sbarufatti and Gianpiero Tagliaferri and Eleonora Troja and The LIGO Scientific Collaboration, and The Virgo Collaboration, and andThe KAGRA Collaboration and A. G. Abac and R. Abbott and H. Abe and I. Abouelfettouh and F. Acernese and K. Ackley and C. Adamcewicz and S. Adhicary and N. Adhikari and R. X. Adhikari and V. K. Adkins and V. B. Adya and C. Affeldt and D. Agarwal and M. Agathos and O. D. Aguiar and I. Aguilar and L. Aiello and A. Ain and T. Akutsu and S. Albanesi and R. A. Alfaidi and A. Al-Jodah and C. Alléné and A. Allocca and S. Al-Shammari and P. A. Altin and S. Alvarez-Lopez and A. Amato and L. Amez-Droz and A. Amorosi and C. Amra and S. Anand and A. Ananyeva and S. B. Anderson and W. G. Anderson and M. Andia and M. Ando and T. Andrade and N. Andres and M. Andrés-Carcasona and T. Andrić and J. Anglin and S. Ansoldi and J. M. Antelis and S. Antier and M. Aoumi and E. Z. Appavuravther and S. Appert and S. K. Apple and K. Arai and A. Araya and M. C. Araya and J. S. Areeda and N. Aritomi and F. Armato and N. Arnaud and M. Arogeti and S. M. Aronson and G. Ashton and Y. Aso and M. Assiduo and S. Assis de Souza Melo and S. M. Aston and P. Astone and F. Aubin and K. AultONeal and G. Avallone and S. Babak and F. Badaracco and C. Badger and S. Bae and S. Bagnasco and E. Bagui and Y. Bai and J. G. Baier and R. Bajpai and T. Baka and M. Ball and G. Ballardin and S. W. Ballmer and S. Banagiri and B. Banerjee and D. Bankar and P. Baral and J. C. Barayoga and B. C. Barish and D. Barker and P. Barneo and F. Barone and B. Barr and L. Barsotti and M. Barsuglia and D. Barta and S. D. Barthelmy and M. A. Barton and I. Bartos and S. Basak and A. Basalaev and R. Bassiri and A. Basti and M. Bawaj and P. Baxi and J. C. Bayley and A. C. Baylor and M. Bazzan and B. Bécsy and V. M. Bedakihale and F. Beirnaert and M. Bejger and D. Belardinelli and A. S. Bell and V. Benedetto and D. Beniwal and W. Benoit and J. D. Bentley and M. Ben Yaala and S. Bera and M. Berbel and F. Bergamin and B. K. Berger and S. Bernuzzi and M. Beroiz and C. P. L. Berry and D. Bersanetti and A. Bertolini and J. Betzwieser and D. Beveridge and N. Bevins and R. Bhandare and U. Bhardwaj and R. Bhatt and D. Bhattacharjee and S. Bhaumik and S. Bhowmick and A. Bianchi and I. A. Bilenko and G. Billingsley and A. Binetti and S. Bini and O. Birnholtz and S. Biscoveanu and A. Bisht and M. Bitossi and M.-A. Bizouard and J. K. Blackburn and C. D. Blair and D. G. Blair and F. Bobba and N. Bode and G. Bogaert and G. Boileau and M. Boldrini and G. N. Bolingbroke and A. Bolliand and L. D. Bonavena and R. Bondarescu and F. Bondu and E. Bonilla and M. S. Bonilla and A. Bonino and R. Bonnand and P. Booker and A. Borchers and V. Boschi and S. Bose and V. Bossilkov and V. Boudart and A. Boumerdassi and A. Bozzi and C. Bradaschia and P. R. Brady and M. Braglia and A. Branch and M. Branchesi and M. Breschi and T. Briant and A. Brillet and M. Brinkmann and P. Brockill and E. Brockmueller and A. F. Brooks and D. D. Brown and M. L. Brozzetti and S. Brunett and G. Bruno and R. Bruntz and J. Bryant and F. Bucci and J. Buchanan and O. Bulashenko and T. Bulik and H. J. Bulten and A. Buonanno and K. Burtnyk and R. 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Costa and R. Cottingham and M. W. Coughlin and A. Couineaux and J.-P. Coulon and S. T. Countryman and J.-F. Coupechoux and B. Cousins and P. Couvares and D. M. Coward and M. J. Cowart and D. C. Coyne and R. Coyne and K. Craig and R. Creed and J. D. E. Creighton and T. D. Creighton and P. Cremonese and A. W. Criswell and J. C. G. Crockett-Gray and M. Croquette and R. Crouch and S. G. Crowder and J. R. Cudell and T. J. Cullen and A. Cumming and E. Cuoco and M. Cusinato and P. Dabadie and T. Dal Canton and S. Dall’Osso and G. Dálya and B. D’Angelo and S. Danilishin and S. D’Antonio and K. Danzmann and K. E. Darroch and L. P. Dartez and A. Dasgupta and S. Datta and V. Dattilo and A. Daumas and N. Davari and I. Dave and A. Davenport and M. Davier and T. F. Davies and D. Davis and L. Davis and M. C. Davis and E. J. Daw and M. Dax and J. De Bolle and M. Deenadayalan and J. Degallaix and M. De Laurentis and S. Deléglise and V. Del Favero and F. De Lillo and D. Dell’Aquila and W. Del Pozzo and F. De Marco and F. De Matteis and V. D’Emilio and N. Demos and T. Dent and A. Depasse and N. DePergola and R. De Pietri and R. De Rosa and C. De Rossi and R. De Simone and A. Dhani and S. Dhurandhar and R. Diab and M. C. Díaz and M. Di Cesare and G. Dideron and N. A. Didio and T. Dietrich and L. Di Fiore and C. Di Fronzo and F. Di Giovanni and M. Di Giovanni and T. Di Girolamo and D. Diksha and A. Di Michele and J. Ding and S. Di Pace and I. Di Palma and F. Di Renzo and Divyajyoti and A. Dmitriev and Z. Doctor and E. Dohmen and P. P. Doleva and L. Donahue and L. D’Onofrio and F. Donovan and K. L. Dooley and T. Dooney and S. Doravari and O. Dorosh and M. Drago and J. C. Driggers and Y. Drori and J.-G. Ducoin and L. Dunn and U. Dupletsa and D. D’Urso and H. Duval and P.-A. Duverne and S. E. Dwyer and C. Eassa and M. Ebersold and T. Eckhardt and G. Eddolls and B. Edelman and T. B. Edo and O. Edy and A. Effler and J. Eichholz and H. Einsle and M. Eisenmann and R. A. Eisenstein and A. Ejlli and M. Emma and E. Engelby and A. J. Engl and L. Errico and R. C. Essick and H. Estellés and D. Estevez and T. Etzel and M. Evans and T. Evstafyeva and B. E. Ewing and J. M. Ezquiaga and F. Fabrizi and F. Faedi and V. Fafone and S. Fairhurst and P. C. Fan and A. M. Farah and B. Farr and W. M. Farr and G. Favaro and M. Favata and M. Fays and M. Fazio and J. Feicht and M. M. Fejer and E. Fenyvesi and D. L. Ferguson and I. Ferrante and T. A. Ferreira and F. Fidecaro and A. Fiori and I. Fiori and M. Fishbach and R. P. Fisher and R. Fittipaldi and V. Fiumara and R. Flaminio and S. M. Fleischer and L. S. Fleming and E. Floden and E. M. Foley and H. Fong and J. A. Font and B. Fornal and P. W. F. Forsyth and K. Franceschetti and N. Franchini and S. Frasca and F. Frasconi and A. Frattale Mascioli and Z. Frei and A. Freise and O. Freitas and R. Frey and W. Frischhertz and P. Fritschel and V. V. Frolov and G. G. Fronzé and M. Fuentes-Garcia and S. Fujii and I. 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Hsieh and C. Hsiung and H. C. Hsu and S.-C. Hsu and W.-F. Hsu and P. Hu and Q. Hu and H. Y. Huang and Y.-J. Huang and Y. Huang and Y. T. Huang and A. D. Huddart and B. Hughey and D. C. Y. Hui and V. Hui and R. Hur and S. Husa and R. Huxford and T. Huynh-Dinh and G. A. Iandolo and A. Iess and K. Inayoshi and Y. Inoue and G. Iorio and J. Irwin and M. Isi and M. A. Ismail and Y. Itoh and M. Iwaya and B. R. Iyer and V. JaberianHamedan and P.-E. Jacquet and S. J. Jadhav and S. P. Jadhav and T. Jain and A. L. James and P. A. James and R. Jamshidi and A. Z. Jan and K. Jani and L. Janiurek and J. Janquart and K. Janssens and N. N. Janthalur and S. Jaraba and P. Jaranowski and P. Jasal and R. Jaume and W. Javed and A. Jennings and W. Jia and J. Jiang and H.-B. Jin and K. Johansmeyer and G. R. Johns and N. A. Johnson and R. Johnston and N. Johny and D. H. Jones and D. I. Jones and R. Jones and S. Jose and P. Joshi and L. Ju and K. Jung and J. Junker and V. Juste and T. Kajita and C. 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North and J. Novak and J. F. Nuño Siles and G. Nurbek and L. K. Nuttall and K. Obayashi and J. Oberling and J. O’Dell and M. Oertel and A. Offermans and G. Oganesyan and J. J. Oh and K. Oh and S. H. Oh and T. O’Hanlon and M. Ohashi and M. Ohkawa and F. Ohme and H. Ohta and A. S. Oliveira and R. Oliveri and V. Oloworaran and B. O’Neal and K. Oohara and B. O’Reilly and N. D. Ormsby and M. Orselli and R. O’Shaughnessy and Y. Oshima and S. Oshino and S. Ossokine and C. Osthelder and D. J. Ottaway and A. Ouzriat and H. Overmier and B. J. Owen and A. E. Pace and R. Pagano and M. A. Page and A. Pai and S. A. Pai and A. Pal and S. Pal and M. A. Palaia and M. Pálfi and P. P. Palma and C. Palomba and K. C. Pan and P. K. Panda and L. Panebianco and P. T. H. Pang and F. Pannarale and B. C. Pant and F. H. Panther and C. D. Panzer and F. Paoletti and A. Paoli and A. Paolone and E. E. Papalexakis and L. Papalini and G. Papigkiotis and A. Parisi and J. Park and W. Parker and G. Pascale and D. Pascucci and A. Pasqualetti and R. Passaquieti and D. Passuello and O. Patane and M. Patel and D. Pathak and M. Pathak and A. Patra and B. Patricelli and A. S. Patron and S. Paul and E. Payne and T. Pearce and M. Pedraza and R. Pegna and A. Pele and F. E. Peña Arellano and S. Penn and M. D. Penuliar and A. Perego and A. Pereira and J. J. Perez and C. Périgois and C. C. Perkins and G. Perna and A. Perreca and J. Perret and S. Perriès and J. W. Perry and D. Pesios and C. Petrillo and H. P. Pfeiffer and H. Pham and K. A. Pham and K. S. Phukon and H. Phurailatpam and O. J. Piccinni and M. Pichot and M. Piendibene and F. Piergiovanni and L. Pierini and G. Pierra and V. Pierro and M. Pietrzak and M. Pillas and F. Pilo and L. Pinard and C. Pineda-Bosque and I. M. Pinto and M. Pinto and B. J. Piotrzkowski and M. Pirello and M. D. Pitkin and A. Placidi and E. Placidi and M. L. Planas and W. Plastino and R. Poggiani and E. Polini and L. Pompili and J. Poon and E. Porcelli and J. Portell and E. K. Porter and C. Posnansky and R. Poulton and J. Powell and M. Pracchia and B. K. Pradhan and T. Pradier and A. K. Prajapati and K. Prasai and R. Prasanna and P. Prasia and G. Pratten and M. Principe and G. A. Prodi and L. Prokhorov and P. Prosposito and L. Prudenzi and A. Puecher and J. Pullin and M. Punturo and F. Puosi and P. Puppo and M. Pürrer and H. Qi and J. Qin and G. Quéméner and V. Quetschke and C. Quigley and P. J. Quinonez and R. Quitzow-James and F. J. Raab and G. Raaijmakers and N. Radulesco and P. Raffai and S. X. Rail and S. Raja and C. Rajan and B. Rajbhandari and D. S. Ramirez and K. E. Ramirez and F. A. Ramis Vidal and A. Ramos-Buades and D. Rana and E. Randel and S. Ranjan and P. Rapagnani and B. Ratto and S. Rawat and A. Ray and V. Raymond and M. Razzano and J. Read and M. Recaman Payo and T. Regimbau and L. Rei and S. Reid and S. W. Reid and D. H. Reitze and P. Relton and A. Renzini and P. Rettegno and B. Revenu and A. Reza and M. Rezac and A. S. Rezaei and F. Ricci and M. Ricci and D. Richards and C. J. Richardson and J. W. Richardson and A. Rijal and K. Riles and H. K. Riley and S. Rinaldi and J. Rittmeyer and C. Robertson and F. Robinet and M. Robinson and A. Rocchi and L. Rolland and J. G. Rollins and M. Romanelli and A. E. Romano and R. Romano and A. Romero and I. M. Romero-Shaw and J. H. Romie and T. J. Roocke and L. Rosa and T. J. Rosauer and C. A. Rose and D. Rosińska and M. P. Ross and M. Rossello and S. Rowan and S. K. Roy and S. Roy and D. Rozza and P. Ruggi and E. Ruiz Morales and K. Ruiz-Rocha and S. Sachdev and T. Sadecki and J. Sadiq and P. Saffarieh and M. R. Sah and S. S. Saha and T. Sainrat and S. Sajith Menon and K. Sakai and M. Sakellariadou and T. Sako and S. Sakon and O. S. Salafia and F. Salces-Carcoba and L. Salconi and M. Saleem and F. Salemi and M. Sallé and S. Salvador and A. Sanchez and E. J. Sanchez and J. H. Sanchez and L. E. Sanchez and N. Sanchis-Gual and J. R. Sanders and E. M. Sänger and T. R. Saravanan and N. Sarin and A. Sasli and P. Sassi and B. Sassolas and H. Satari and R. Sato and S. Sato and Y. Sato and O. Sauter and R. L. Savage and T. Sawada and H. L. Sawant and S. Sayah and D. Schaetzl and M. Scheel and J. Scheuer and M. G. Schiworski and P. Schmidt and S. Schmidt and R. Schnabel and M. Schneewind and R. M. S. Schofield and K. Schouteden and H. Schuler and B. W. Schulte and B. F. Schutz and E. Schwartz and J. Scott and S. M. Scott and T. C. Seetharamu and M. Seglar-Arroyo and Y. Sekiguchi and D. Sellers and A. S. Sengupta and D. Sentenac and E. G. Seo and J. W. Seo and V. Sequino and M. Serra and G. Servignat and Y. Setyawati and T. Shaffer and U. S. Shah and M. S. Shahriar and M. A. Shaikh and B. Shams and L. Shao and A. K. Sharma and P. Sharma and S. Sharma-Chaudhary and P. Shawhan and N. S. Shcheblanov and B. Shen and Y. Shikano and M. Shikauchi and K. Shimode and H. Shinkai and J. Shiota and D. H. Shoemaker and D. M. Shoemaker and R. W. Short and S. ShyamSundar and A. Sider and H. Siegel and M. Sieniawska and D. Sigg and L. Silenzi and M. Simmonds and L. P. Singer and A. Singh and D. Singh and M. K. Singh and A. Singha and A. M. Sintes and V. Sipala and V. Skliris and B. J. J. Slagmolen and T. J. Slaven-Blair and J. Smetana and J. R. Smith and L. Smith and R. J. E. Smith and W. J. Smith and J. Soldateschi and S. N. Somala and K. Somiya and K. Soni and S. Soni and V. Sordini and F. Sorrentino and N. Sorrentino and R. Soulard and T. Souradeep and A. Southgate and E. Sowell and V. Spagnuolo and A. P. Spencer and M. Spera and P. Spinicelli and A. K. Srivastava and F. Stachurski and D. A. Steer and J. Steinlechner and S. Steinlechner and N. Stergioulas and P. Stevens and M. StPierre and L. C. Strang and G. Stratta and M. D. Strong and A. Strunk and R. Sturani and A. L. Stuver and M. Suchenek and S. Sudhagar and N. Sueltmann and A. G. Sullivan and K. D. Sullivan and L. Sun and S. Sunil and A. Sur and J. Suresh and P. J. Sutton and Takamasa Suzuki and Takanori Suzuki and B. L. Swinkels and A. Syx and M. J. Szczepańczyk and P. Szewczyk and M. Tacca and H. Tagoshi and S. C. Tait and H. Takahashi and R. Takahashi and A. Takamori and K. Takatani and H. Takeda and M. Takeda and C. J. Talbot and C. Talbot and M. Tamaki and N. Tamanini and D. Tanabe and K. Tanaka and S. J. Tanaka and T. Tanaka and A. J. Tanasijczuk and D. Tang and S. Tanioka and D. B. Tanner and L. Tao and R. D. Tapia and E. N. Tapia San Martín and R. Tarafder and C. Taranto and A. Taruya and J. D. Tasson and M. Teloi and R. Tenorio and H. Themann and A. Theodoropoulos and M. P. Thirugnanasambandam and L. M. Thomas and M. Thomas and P. Thomas and J. E. Thompson and S. R. Thondapu and K. A. Thorne and E. Thrane and J. Tissino and A. Tiwari and Shubhanshu Tiwari and Srishti Tiwari and V. Tiwari and M. R. Todd and A. M. Toivonen and K. Toland and A. E. Tolley and T. Tomaru and K. Tomita and T. Tomura and C. Tong-Yu and A. Toriyama and N. Toropov and A. Torres-Forné and C. I. Torrie and M. Toscani and I. Tosta e Melo and E. Tournefier and A. A. Trani and A. Trapananti and F. Travasso and G. Traylor and J. Trenado and M. Trevor and M. C. Tringali and A. Tripathee and L. Troiano and A. Trovato and L. Trozzo and R. J. Trudeau and T. T. L. Tsang and R. Tso and S. Tsuchida and L. Tsukada and T. Tsutsui and K. Turbang and M. Turconi and C. Turski and H. Ubach and A. S. Ubhi and N. Uchikata and T. Uchiyama and R. P. Udall and T. Uehara and K. Ueno and C. S. Unnikrishnan and T. Ushiba and A. Utina and M. Vacatello and H. Vahlbruch and N. Vaidya and G. Vajente and A. Vajpeyi and G. Valdes and J. Valencia and M. Valentini and S. A. Vallejo-Peña and S. Vallero and V. Valsan and N. van Bakel and M. van Beuzekom and M. van Dael and J. F. J. van den Brand and C. Van Den Broeck and D. C. Vander-Hyde and M. van der Sluys and A. Van de Walle and J. van Dongen and K. Vandra and H. van Haevermaet and J. V. van Heijningen and J. Vanosky and M. H. P. M. van Putten and Z. van Ranst and N. van Remortel and M. Vardaro and A. F. Vargas and V. Varma and M. Vasúth and A. Vecchio and G. Vedovato and J. Veitch and P. J. Veitch and S. Venikoudis and J. Venneberg and P. Verdier and D. Verkindt and B. Verma and P. Verma and Y. Verma and S. M. Vermeulen and D. Veske and F. Vetrano and A. Veutro and A. M. Vibhute and A. Viceré and S. Vidyant and A. D. Viets and A. Vijaykumar and A. Vilkha and V. Villa-Ortega and E. T. Vincent and J.-Y. Vinet and S. Viret and A. Virtuoso and S. Vitale and H. Vocca and D. Voigt and E. R. G. von Reis and J. S. A. von Wrangel and S. P. Vyatchanin and L. E. Wade and M. Wade and K. J. Wagner and R. C. Walet and M. Walker and G. S. Wallace and L. Wallace and H. Wang and J. Z. Wang and W. H. Wang and Z. Wang and G. Waratkar and R. L. Ward and J. Warner and M. Was and T. Washimi and N. Y. Washington and D. Watarai and K. E. Wayt and B. Weaver and C. R. Weaving and S. A. Webster and M. Weinert and A. J. Weinstein and R. Weiss and C. M. Weller and R. A. Weller and F. Wellmann and L. Wen and P. Weßels and K. Wette and J. T. Whelan and D. D. White and B. F. Whiting and C. Whittle and J. B. Wildberger and O. S. Wilk and D. Wilken and K. Willetts and D. Williams and M. J. Williams and N. S. Williams and J. L. Willis and B. Willke and M. Wils and C. C. Wipf and G. Woan and J. Woehler and J. K. Wofford and N. E. Wolfe and D. Wong and H. T. Wong and H. W. Y. Wong and I. C. F. Wong and J. L. Wright and M. Wright and C. Wu and D. S. Wu and H. Wu and D. M. Wysocki and L. Xiao and V. A. Xu and Y. Xu and N. Yadav and H. Yamamoto and K. Yamamoto and M. Yamamoto and T. S. Yamamoto and T. Yamamoto and S. Yamamura and R. Yamazaki and S. Yan and T. Yan and F. W. Yang and F. Yang and K. Z. Yang and L.-C. Yang and Y. Yang and Z. Yarbrough and S.-W. Yeh and A. B. Yelikar and S. M. C. Yeung and X. Yin and J. Yokoyama and T. Yokozawa and J. Yoo and H. Yu and H. Yuzurihara and A. Zadrożny and A. J. Zannelli and M. Zanolin and M. Zeeshan and T. Zelenova and J.-P. Zendri and M. Zeoli and M. Zerrad and M. Zevin and A. C. Zhang and J. Zhang and L. Zhang and R. Zhang and T. Zhang and Y. Zhang and C. Zhao and Yue Zhao and Yuhang Zhao and Y. Zheng and H. Zhong and S. Zhong and R. Zhou and Z.-H. Zhu and A. B. Zimmerman and M. E. Zucker and J. Zweizig}, doi = {10.3847/1538-4357/ad9749}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {207}, shortjournal = {The Astrophys. J.}, title = {Swift-BAT GUANO follow-up of gravitational-wave triggers in the third LIGO–Virgo–KAGRA observing run}, volume = {980}, year = {2025}, }
• (2025). Relative alpha in the magnetohydrodynamics with open magnetic field boundary and its application to the solar eruption. ApJ, 980(2), 206. (www)

  @article{ , abstract = {An instability criterion in the magnetohydrodynamics (MHD) with the open boundary of a magnetic field is proposed in this paper. We use a series of linear force-free extrapolation fields, in which the normal part of the magnetic field is fixed, to obtain the linear fitting coefficient called relative alpha by using the cojoined value of magnetic free energy and magnetic flux at the open boundary ( E f Φ 2 ) and the square of relative magnetic helicity ( {H}_{R}^{2} ). We calculate this coefficient of the magnetic field above active regions NOAA 8210 and NOAA 11429 obtained by the photospheric-data-driven MHD model. It is found that the fitting coefficient is a good proxy of the criterion to indicate the occurrence of instability after which the magnetic reconnection happens and causes the fast release of magnetic energy. We also applied this method to the continuous evolution of the three-dimensional magnetic field of NOAA 11158 based on the measurement of the photospheric vector magnetic field of Solar Dynamics Observatory/Helioseismic and Magnetic Imager by the nonlinear force-free extrapolation method. The calculated coefficient when the major flare happened based on the extrapolation data is very close to the expected ones, which perfectly reflects the occurrence of instability, and the difference is even less than 7%. This relative alpha is very helpful to evaluate how far it is from the instability in the MHD and quantitatively estimate the occurrence of solar eruption in the space weather forecast.}, archive = {J_ApJ}, author = {Shangbin Yang and Jörg Büchner and Jean Carlo Santos and Jan Skála and Hongqi Zhang}, doi = {10.3847/1538-4357/ada278}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {206}, shortjournal = {The Astrophys. J.}, title = {Relative alpha in the magnetohydrodynamics with open magnetic field boundary and its application to the solar eruption}, volume = {980}, year = {2025}, }
• (2025). A novel survey for young substellar objects with the W-band filter. VII. water-bearing objects in the core of the ρ ophiuchi cloud complex. ApJ, 980(2), 205. (www)

  @article{ , abstract = {We present a study of very low mass stars and brown dwarfs in the rich star-forming core of the ρ Ophiuchi cloud complex. The selection of the sample relies on detecting the inherent water absorption characteristic in young substellar objects. Of the 22 water-bearing candidates selected, 15 have a spectral type of M6 or later. Brown dwarf candidates too faint for membership determination by Gaia have their proper motions derived by deep-infrared images spanning 6 yr. Astrometric analysis confirms 21/22 sources as members, with one identified as a contaminant. Infrared colors and the spectral energy distribution of each water-bearing candidate are used to diagnose the mass, age, and possible existence of circumstellar dust. A total of 15 sources exhibit evidence of disks in their spectral energy distributions, as late as in M8-type objects. Spectroscopy for bright candidates has confirmed one as an M8 member and verified two sources (with disks) exhibiting signatures of magnetospheric accretion.}, archive = {J_ApJ}, author = {Tanvi Sharma and Wen Ping Chen and Beth Biller and Loïc Albert and Belinda Damian and Jessy Jose and Bhavana Lalchand and Michael C. Liu and Yumiko Oasa}, doi = {10.3847/1538-4357/ada3c3}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {205}, shortjournal = {The Astrophys. J.}, title = {A novel survey for young substellar objects with the W-band filter. VII. water-bearing objects in the core of the ρ ophiuchi cloud complex}, volume = {980}, year = {2025}, }
• (2025). COSMOS-web: The role of galaxy interactions and disk instabilities in producing starbursts at z < 4. ApJ, 980(2), 204. (www)

  @article{ , abstract = {We study of the role of galaxy–galaxy interactions and disk instabilities in producing starburst activity in galaxies out to z = 4. For this, we use a sample of 387 galaxies with robust total star formation rate measurements from Herschel, gas masses from the Atacama Large Millimeter/submillimeter Array, stellar masses and redshifts from multiband photometry, and JWST/NIRCam rest-frame optical imaging. Using mass-controlled samples, we find an increased fraction of interacting galaxies in the starburst regime at all redshifts out to z = 4. This increase correlates with star formation efficiency (SFE) but not with gas fraction. However, the correlation is weak (and only significant out to z = 2), which could be explained by the short duration of SFE increase during interaction. In addition, we find that isolated disk galaxies make up a significant fraction of the starburst population. The fraction of such galaxies with star-forming clumps ("clumpy disks") is significantly increased compared to the main-sequence disk population. Furthermore, this fraction directly correlates with SFE. This is direct observational evidence for a long-term increase of SFE maintained due to disk instabilities, contributing to the majority of starburst galaxies in our sample and hence to substantial mass growth in these systems. This result could also be of importance for explaining the growth of the most massive galaxies at z > 6.}, archive = {J_ApJ}, author = {Andreas L. Faisst and Lilan Yang and M. Brinch and C. M. Casey and N. Chartab and M. Dessauges-Zavadsky and N. E. Drakos and S. Gillman and G. Gozaliasl and C. C. Hayward and O. Ilbert and P. Jablonka and A. Kaminsky and J. S. Kartaltepe and A. M. Koekemoer and V. Kokorev and E. Lambrides and D. Liu and C. Maraston and C. L. Martin and A. Renzini and B. E. Robertson and D. B. Sanders and Z. Sattari and N. Scoville and C. M. Urry and A. P. Vijayan and J. R. Weaver and H. B. Akins and N. Allen and R. C. Arango-Toro and O. R. Cooper and M. Franco and F. Gentile and S. Harish and M. Hirschmann and A. A. Khostovan and C. Laigle and R. L. Larson and M. Lee and Z. Liu and A. S. Long and G. Magdis and R. Massey and H. J. McCracken and J. McKinney and L. Paquereau and J. Rhodes and R. M. Rich and M. Shuntov and J. D. Silverman and M. Talia and S. Toft and J. A. Zavala}, doi = {10.3847/1538-4357/ada566}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {204}, shortjournal = {The Astrophys. J.}, title = {COSMOS-web: The role of galaxy interactions and disk instabilities in producing starbursts at z < 4}, volume = {980}, year = {2025}, }
• (2025). Energy extraction from a black hole by a strongly magnetized thin accretion disk. ApJ, 980(2), 203. (www)

  @article{ , abstract = {The presence of a strong, large-scale magnetic field in an accretion flow leads to the extraction of the rotational energy of the black hole (BH) through the Blandford–Znajek (BZ) process, believed to power relativistic jets in various astrophysical sources. We study rotational energy extraction from a BH surrounded by a highly magnetized thin disk by performing a set of 3D global GRMHD simulations. We find that the saturated flux threading the BH has a weaker dependence on BH spin, compared to highly magnetized hot (geometrically thick) accretion flows. Also, we find that only a fraction (10%–70%) of the extracted BZ power is channeled into the jet, depending on the spin parameter. The remaining energy is potentially used to launch winds or contribute to the radiative output of the disk or corona. Our simulations reveal that the presence of a strong magnetic field enhances the radiative efficiency of the disk, making it more luminous than its weakly magnetized counterpart or the standard disk model. We attribute this excess luminosity primarily to the enhanced magnetic dissipation in the intra-ISCO region. Our findings have implications for understanding X-ray corona formation and BH spin measurements, and interpreting BH transient phenomena.}, archive = {J_ApJ}, author = {Prasun Dhang and Jason Dexter and Mitchell C. Begelman}, doi = {10.3847/1538-4357/ada76e}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {203}, shortjournal = {The Astrophys. J.}, title = {Energy extraction from a black hole by a strongly magnetized thin accretion disk}, volume = {980}, year = {2025}, }
• (2025). Anomalous neutral hydrogen column densities in local interstellar medium clouds*. ApJ, 980(2), 202. (www)

  @article{ , abstract = {Analysis of high-resolution spectra of the hydrogen and deuterium Ly α lines provides measurements of interstellar neutral hydrogen column densities N (H i ) to 113 stars within 50 pc of the Sun. Plots of N (H i ) versus distance through the LIC, G, Mic, and other clouds in the local interstellar medium (LISM) show very interesting properties. For the LIC and G clouds, nearly all of the observed neutral hydrogen occurs within 3 or 4 pc of the Sun with no significant additional neutral hydrogen at larger distances out to 50 pc, except for several sight lines with anomalously high N (H i ). Scatter about the mean hydrogen column density in the LIC is several times larger than the measurement errors. We evaluate several possible sources of the high N (H i ) sight lines. Seven sight lines with anomalously high N (H i ) are aligned perpendicular to the line connecting the centers of the LIC and G clouds where the two clouds merge creating a mixed cloud region. The high N (H i ) in these seven sight lines can be explained by their paths through an irregularly shaped mixed cloud region where the neutral hydrogen number density is the sum for both clouds. However, the most recent nearby supernova explosion created a shell that is seen in nearly the same direction perpendicular to the LIC/G axis and may also explain these seven high N (H i ) sight lines. Other possible explanations for the high N (H i ) sight lines include interstellar shocks, wakes produced by stars moving rapidly through the LISM, and regions where other clouds may overlap.}, archive = {J_ApJ}, author = {Jeffrey L. Linsky and Seth Redfield}, doi = {10.3847/1538-4357/ada89e}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {202}, shortjournal = {The Astrophys. J.}, title = {Anomalous neutral hydrogen column densities in local interstellar medium clouds*}, volume = {980}, year = {2025}, }
• (2025). Three-dimensional transport of solids in a protoplanetary disk containing a growing giant planet. ApJ, 980(2), 201. (www)

  @article{ , abstract = {We present the results of combined hydrodynamic and particle tracking post-processing modeling to study the transport of small dust in a protoplanetary disk containing an embedded embryo in three dimensions. We use a suite of FARGO3D hydrodynamic simulations of disks containing a planetary embryo varying in mass up to 300 M ⊕ on a fixed orbit in both high- and low-viscosity disks. We then simulate solid particles through the disk as a post-processing step using a Monte Carlo integration, allowing us to track the trajectories of individual particles as they travel throughout the disk. We find that gas advection onto the planet can carry small, well-coupled solids across the gap opened in the disk by the embedded planet for planetary masses above the pebble isolation mass. This mixing between the inner and outer disk can occur in both directions, with solids in the inner disk mixing to the outer disk as well. Additionally, in low-viscosity disks, multiple dust pile-ups in the outer disk may preserve isotopic heterogeneities, possibly providing an outermost tertiary isotopic reservoir. Throughout Jupiter's growth, the extent of mixing between isotopic reservoirs varied depending on dust size, gas turbulence, and the Jovian embryo mass.}, archive = {J_ApJ}, author = {Eric Van Clepper and Ellen M. Price and Fred J. Ciesla}, doi = {10.3847/1538-4357/ada8a4}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {201}, shortjournal = {The Astrophys. J.}, title = {Three-dimensional transport of solids in a protoplanetary disk containing a growing giant planet}, volume = {980}, year = {2025}, }
• (2025). UNCOVERing the faint end of the z ∼ 7 [O iii] luminosity function with JWST’s F410M medium bandpass filter. ApJ, 980(2), 200. (www)

  @article{ , abstract = {Strong emission from doubly ionized oxygen is a beacon for some of the most intensely star-forming galaxies. JWST enables the search for this beacon in the early Universe with unprecedented sensitivity. Using UNCOVER DR1 JWST/NIRCam and Hubble Space Telescope (HST) imaging data of A2744, we identify strong (rest-frame EW >  500Å) [O iii ] 5008 emitters at z ∼ 7 based on excess F410M flux. We find N = 68 z ∼ 7 [O iii ] candidates, including N = 33 with deep HST coverage required to rule out lower-redshift interlopers (13.68 arcmin 2 with F814W 5 σ depth  >28 AB). Such strong emission lines can produce very red colors often misinterpreted as evidence for old, massive stellar populations, but are shown to be emission lines where we have spectra. Using this deep HST sample, we derive a new [O iii ] luminosity function (LF) spanning 41.1\lt {{\rm{log}}}_{10}(L/{{\rm{erg}}\,{\rm{s}}}^{-1})\lt 42.4 , an order of magnitude deeper than previous z ∼ 6 studies. This LF is fit by a power law with a faint-end slope of \alpha =-2.0{7}_{-0.23}^{+0.22} . Our results are consistent with the z ∼ 7 FRESCO [O iii ] LF across the overlapping 0.5 dex range, 41.9\gt {{\rm{log}}}_{10}(L/{{\rm{erg}}\,{\rm{s}}}^{-1})\gt 42.4 . Combining both data sets, we construct an LF spanning 2 dex in luminosity, with a best-fit Schechter function: \alpha =-2.1{3}_{-0.16}^{+0.15} , {{\rm{log}}}_{10}({\phi }^{* }/{{\rm{Mpc}}}^{-3})=-4.1{7}_{-1.39}^{+0.49} , and {{\rm{log}}}_{10}({L}^{* }/ erg s {}^{-1})=43.0{6}_{-0.29}^{+0.90} . There is little evolution between this LF and published [O iii ] LFs at 3 < z < 8, and no evidence of a turnover at faint luminosities. The sizes of these extreme [O iii ] emitters are similar to their low redshift counterparts, the Green Peas. The z ∼ 7 [O iii ] LF aligns with the Ly α LF at the bright end, suggesting many of these galaxies are also Ly α emitters.}, archive = {J_ApJ}, author = {Isak G. B. Wold and Sangeeta Malhotra and James E. Rhoads and John R. Weaver and Bingjie Wang}, doi = {10.3847/1538-4357/ada8a6}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {200}, shortjournal = {The Astrophys. J.}, title = {UNCOVERing the faint end of the z ∼ 7 [O iii] luminosity function with JWST’s F410M medium bandpass filter}, volume = {980}, year = {2025}, }
• (2025). Resolving an asteroseismic catastrophe: Structural diagnostics from p-mode phase functions off the main sequence. ApJ, 980(2), 199. (www)

  @article{ , abstract = {On the main sequence, the asteroseismic small frequency separation δν 02 between radial and quadrupole p -modes is customarily interpreted to be a direct diagnostic of internal structure. Such an interpretation is based on a well-known integral estimator relating δν 02 to a radially averaged sound-speed gradient. However, this estimator fails, catastrophically, when evaluated on structural models of red giants: their small separations must therefore be interpreted differently. We derive a single expression that both reduces to the classical estimator when applied to main-sequence stellar models and reproduces the qualitative features of the small separation for stellar models of very evolved red giants. This expression indicates that the small separations of red giants scale primarily with their global seismic properties as \delta {\nu }_{02}\propto {\rm{\Delta }}{\nu }^{2}/{\nu }_{{\rm{\max }}} , rather than being in any way sensitive to their internal structure. Departures from this asymptotic behavior, during the transition from the main-sequence to red giant regimes, have been recently reported in open-cluster Christensen–Dalsgaard (C-D) diagrams from K2 mission data. Investigating them in detail, we demonstrate that they occur when the convective envelope boundary passes a specific acoustic distance—roughly one-third of a wavelength at {\nu }_{{\rm{\max }}} —from the center of the star, at which point radial modes become maximally sensitive to the position of the boundary. The shape of the corresponding features on p and C-D (or r 02 ) diagrams may be useful in constraining the nature of convective boundary mixing in the context of undershooting beneath a convective envelope.}, archive = {J_ApJ}, author = {J. M. Joel Ong and Christopher J. Lindsay and Claudia Reyes and Dennis Stello and Ian W. Roxburgh}, doi = {10.3847/1538-4357/ada949}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {199}, shortjournal = {The Astrophys. J.}, title = {Resolving an asteroseismic catastrophe: Structural diagnostics from p-mode phase functions off the main sequence}, volume = {980}, year = {2025}, }
• (2025). The impact of extended CO2 cross sections on temperate anoxic planet atmospheres. ApJ, 980(2), 198. (www)

  @article{ , abstract = {Our interpretation of terrestrial exoplanet atmospheric spectra will always be limited by the accuracy of the data we use as input in our forward and retrieval models. Ultraviolet molecular absorption cross sections are one category of these essential model inputs; however, they are often poorly characterized at the longest wavelengths relevant to photodissociation. Photolysis reactions dominate the chemical kinetics of temperate terrestrial planet atmospheres. One molecule of particular importance is CO 2 , which is likely present in all terrestrial planet atmospheres. The photolysis of CO 2 can introduce CO and O, as well as shield tropospheric water vapor from undergoing photolysis. This is important because H 2 O photolysis produces OH, which serves as a major reactive sink to many atmospheric trace gases. Here, we construct CO 2 cross-section prescriptions at 195 K and 300 K extrapolated beyond 200 nm from measured cross sections. We compare results from the implementation of these new cross sections to the most commonly used CO 2 prescriptions for temperate terrestrial planets with Archean-like atmospheres. We generally find that the observational consequences of CO 2 dissociation beyond 200 nm are minimal so long as our least conservative (highest opacity) prescription can be ruled out. Moreover, implementing our recommended extended CO 2 cross sections does not substantially alter previous results that show the consequential photochemical impact of extended H 2 O cross sections.}, archive = {J_ApJ}, author = {Wynter Broussard and Edward W. Schwieterman and Clara Sousa-Silva and Grace Sanger-Johnson and Sukrit Ranjan and Olivia Venot}, doi = {10.3847/1538-4357/adaaf0}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {198}, shortjournal = {The Astrophys. J.}, title = {The impact of extended CO2 cross sections on temperate anoxic planet atmospheres}, volume = {980}, year = {2025}, }
• (2025). The fallibility of equipartition magnetic field strengths from synchrotron emission using synthetically observed galaxies. ApJ, 980(2), 197. (www)

  @article{ , abstract = {Understanding the role that magnetic fields play on the stage of galaxy formation requires accurate methods for inferring the properties of extragalactic magnetic fields. Radio synchrotron emission has been the most promising avenue to infer magnetic field strengths across galaxies, with the application of a central assumption: that galactic cosmic rays are in energy equipartition with the magnetic field. In this work, we leverage flexible synthetic observations of a high-resolution magnetohydrodynamic simulation of a Milky Way–like galaxy to review whether true equipartition is capable of reproducing radio observations of galaxies, and investigate its impact on the inference of magnetic field strengths when varying the properties and density distribution of the cosmic rays. We find that imposing equipartition (regardless of scale length) results in cosmic ray electron densities that are unable to generate either the amplitude or the shape of the radio intensity profiles typically observed in spiral galaxies. Instead, observationally motivated smooth distributions of cosmic ray electrons across the galaxy provide a remarkable match to observations. We further demonstrate that assuming equipartition with those mock observations can lead to significant overestimation of the magnetic field strength. This misestimation varies with cosmic ray electron densities, cosmic ray spectrum power-law index, and galactic environment, aggravated in inter-arm regions and attenuated in star-forming regions. Our results promote caution when assuming equipartition in observations, and suggest that additional theoretical and numerical work is required to leverage the upcoming generation of radio observations poised to revolutionize our understanding of astrophysical magnetic fields.}, archive = {J_ApJ}, author = {Tara Dacunha and Sergio Martin-Alvarez and Susan E. Clark and Enrique Lopez-Rodriguez}, doi = {10.3847/1538-4357/adab72}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {197}, shortjournal = {The Astrophys. J.}, title = {The fallibility of equipartition magnetic field strengths from synchrotron emission using synthetically observed galaxies}, volume = {980}, year = {2025}, }
• (2025). Magnetic activities of AD leonis: Flares in TESS data and optical spectra. ApJ, 980(2), 196. (www)

  @article{ , abstract = {We studied the flaring activities of M4.5 dwarf AD Leo to understand its stellar atmospheres and magnetic activities. We present new observational results on this highly active star, using nonsimultaneous measurement of Transiting Exoplanet Survey Satellite (TESS) data, time-series optical spectra, and Giant Meter Radio Telescope 325 MHz radio data. We revisited the rotation period of 2.23 ± 0.04 days from TESS, which matches well with previously measured literature values. We estimated an extremely rare high-energy superflare of 4.9 × 10 35 erg and ∼400 minute duration with a high magnetic field strength of 1.2 kG. Interestingly, we correlated the duration of a flare event with its energy, τ ∝ {E}_{\mathrm{bol}}^{0.60\pm 0.02} , and noticed a discrepancy between stellar and solar flares suggesting a difference in coronal magnetic field strength. From time-series spectra, we observed H α spectral flares in the range of 10 30 –10 31 erg. A 12 minute delay in a spectral flare event was observed between the emission of the H α and Ca ii H and K lines, possibly due to their origination at different spatial locations in the chromosphere. We noticed the deviation in flare rate distribution and orbital phases indicates the presence of highly active regions. Furthermore, an occasional radio detection with a flux density of 9.46 ± 1.63 mJy at a frequency of 325 MHz might be coherent emission in the presence of the magnetic field, giving a hint of star–planet interaction.}, archive = {J_ApJ}, author = {Diya Ram and Soumen Mondal and Dusmanta Patra and Samrat Ghosh and Rajib Khumbhakar}, doi = {10.3847/1538-4357/adabc3}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {196}, shortjournal = {The Astrophys. J.}, title = {Magnetic activities of AD leonis: Flares in TESS data and optical spectra}, volume = {980}, year = {2025}, }
• (2025). The Oxidation–Deuteration processes of large, astronomically relevant cationic polycyclic aromatic hydrocarbons. ApJ, 980(2), 195. (www)

  @article{ , abstract = {In interstellar environments, gas-phase polycyclic aromatic hydrocarbon (PAH) predominantly involves (photo)fragmentation, hydrogenation, and oxidation chemical routes, which lead to the formation of complex organic species. Here the gas-phase reactions between tribenzo-naphtho-pero-pyrene (TNPP, C 40 H 18 ) cations and ultraviolet, 18/16 O or D atoms are investigated. The oxidized TNPP cations ([C 40 H 18/17/16 O n ] + , n = [1, 6]) are newly formed; the collision-induced deoxidation of oxidized TNPP cations is followed by the loss of HCO/CO units. With laser irradiation, the photo-deoxidation of oxidized TNPP cations is identified. Smaller PAH cations, [C 40− n H 18− n ] + , with n = [1, 5], i.e., PAHs containing odd carbon numbers (e.g., 39, 37 C atoms), are produced. Furthermore, the oxidized–deuterated TNPP cations ([C 40 H m D n O x ] + ) are well formed upon simultaneous reaction with O and D atoms. The structure of the oxidized–deuterated TNPP cations and the bonding energy for these reaction pathways were investigated with theoretical calculations. Four oxidation bonding types are identified together with their evolution pathways. The reaction energy is relatively high, and the addition of O/D atoms to the carbon skeleton is a relatively random and independent event, i.e., with no restrictions or requirements for the carbon sites of PAH species. Consequently, the oxidized–deuterated states and forms of PAH compounds are intricate and complex. Furthermore, the calculations confirm that the loss of CO or H+CO is energetically preferable. Importantly, the formation of the carbonyl unit is confirmed. We infer that the collision/photo-induced deoxidation (loss of (H)CO units) of oxidized PAH species is involved in the top-down evolution routes of large PAHs and effectively catalyzes the potential formation of small oxygen-containing species (e.g., OH/HCO/CO) in the interstellar medium.}, archive = {J_ApJ}, author = {Xiaoyi Hu and Nian Zhao and Congcong Zhang and Xuejuan Yang and Alexander G. G. M. Tielens and Junfeng Zhen}, doi = {10.3847/1538-4357/adabdf}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {195}, shortjournal = {The Astrophys. J.}, title = {The Oxidation–Deuteration processes of large, astronomically relevant cationic polycyclic aromatic hydrocarbons}, volume = {980}, year = {2025}, }
• (2025). Observations of the X-ray millihertz quasiperiodic oscillations in hercules X-1. ApJ, 980(2), 194. (www)

  @article{ , abstract = {With a systematic timing investigation of the persistent X-ray binary pulsar Her X-1 based on a large number of Insight-HXMT observations between 2017 and 2019, we confirm the presence of X-ray millihertz quasiperiodic oscillations (mHz QPOs) at ∼0.01 Hz. By applying wavelet analysis in our data analysis procedures, we first identify ∼0.005–0.009 Hz QPOs coexisting with the ∼0.01 Hz QPOs. Wavelet analysis suggests that these QPO features show transient behaviors, that the frequencies of mHz QPOs evolve in short timescales. There exists a positive relation between QPO centroid frequency (from ∼0.005 to 0.009 Hz) and X-ray luminosity, while the 10 mHz QPO frequencies remain nearly constant for different luminosities, which suggests different physical mechanisms for the two types of mHz QPOs. The 10 mHz QPOs in both X-ray and UV bands would have the same origin related to the beat frequency where the Alfvén radius is close to the corotation radius, and the 5 mHz QPOs may originate from magnetic disk precession.}, archive = {J_ApJ}, author = {Wen Yang and Wei Wang}, doi = {10.3847/1538-4357/adae8f}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {194}, shortjournal = {The Astrophys. J.}, title = {Observations of the X-ray millihertz quasiperiodic oscillations in hercules X-1}, volume = {980}, year = {2025}, }
• (2025). Adiabatic index in fluid models of collisionless black hole accretion. ApJ, 980(2), 193. (www)

  @article{ , abstract = {Models of highly sub-Eddington accretion onto black holes commonly use a single-fluid model for the collisionless, near-horizon plasma. These models must specify an equation of state. It is common to use an ideal gas with p = ( γ − 1) u and γ = 4/3, 13/9, or 5/3, but these produce significantly different outcomes. We discuss the origins of this discrepancy and the assumptions underlying the single-fluid model. The main result of this investigation is that under conditions relevant to low-luminosity black hole accretion the best choice of single-fluid adiabatic index is close to but slightly less than 5/3. Along the way we provide a simple equilibrium model for the relation between the ion-to-electron dissipation ratio and the ion-to-electron temperature ratio, and explore the implications for electron temperature fluctuations in Event Horizon Telescope sources.}, archive = {J_ApJ}, author = {Charles F. Gammie}, doi = {10.3847/1538-4357/adaea3}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {193}, shortjournal = {The Astrophys. J.}, title = {Adiabatic index in fluid models of collisionless black hole accretion}, volume = {980}, year = {2025}, }
• (2025). Starburst galaxies in their last billion years: An hδ absorption line selected sample. ApJ, 980(2), 192. (www)

  @article{ , abstract = {In this paper, we focus on the study of starburst galaxies in their final billion years. Our galaxy selection is based solely on the presence of the H δ absorption line, which permits the later evolution of starburst galaxies to be traced, coinciding with the emergence of A-type stars in these galaxies. We propose a novel method that utilizes star formation rate and UVJ colors to classify galaxies in the sample, and use the spectral features to mark their stages of evolution. Our in-depth analysis of the Mg ii line indicates the substantial increase in the number of F- and G-type stars when a galaxy evolves from star-forming to quiescent phase. Furthermore, we identify active galactic nuclei in this sample to explore their roles in the later stage of the star formation history of galaxies.}, archive = {J_ApJ}, author = {Shumei Wu and Jia-Sheng Huang and Cheng Cheng and Y. Sophia Dai}, doi = {10.3847/1538-4357/ada3bf}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {192}, shortjournal = {The Astrophys. J.}, title = {Starburst galaxies in their last billion years: An hδ absorption line selected sample}, volume = {980}, year = {2025}, }
• (2025). Equatorial enhancement in the dustiest OH/IR stars in the galactic bulge. ApJ, 980(2), 191. (www)

  @article{ , abstract = {We have detected the 10 μ m silicate feature and the 11.3 μ m crystalline forsterite feature in absorption in 21 oxygen-rich asymptotic giant branch stars in the Galactic bulge. The depths of the 10 μ m feature indicate highly obscured circumstellar environments. The additional crystalline features may suggest either an extended envelope or dust formation in a high-density environment. We have also modeled the spectral energy distributions (SEDs) of the sample using radiative transfer models, and compared the results to wind speeds measured using 1612 MHz circumstellar OH masers, as well as previous estimates of circumstellar properties. The 16 sources with measured pulsation periods appear on sequence D of the mid-IR period–luminosity relation, associated with the long secondary period. We suspect that all of these sources are in fact fundamental-mode pulsators. At least two sources appear on the fundamental-mode sequence when accounting for the dust content. For the remainder, these sources are also likely fundamental-mode pulsators with extended envelopes. Taken as a whole, the high optical depths, crystalline features, discrepancies between observed and modeled wind speeds, pulsation periods longer than other fundamental-mode pulsators, and SED and pulsation properties similar to those with known equatorially enhanced circumstellar envelopes (e.g., OH 26.5+0.6 and OH 30.1–0.7) lead us to believe that these sources are likely to be equatorially enhanced.}, archive = {J_ApJ}, author = {Steven R. Goldman and Jacco Th. van Loon and Olivia C. Jones and Joris A. D. L. Blommaert and Martin A. T. Groenewegen}, doi = {10.3847/1538-4357/ada6ad}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {191}, shortjournal = {The Astrophys. J.}, title = {Equatorial enhancement in the dustiest OH/IR stars in the galactic bulge}, volume = {980}, year = {2025}, }
• (2025). Effects of subhalos on interpreting highly magnified sources near lensing caustics. ApJ, 980(2), 190. (www)

  @article{ , abstract = {Large magnification factors near gravitational lensing caustics of galaxy-cluster lenses allow the study of individual stars or compact stellar associations at cosmological distances. We study how the presence of sub-galactic subhalos, an inevitable consequence of cold dark matter, can alter the property of caustics and hence change the interpretation of highly magnified sources that lie atop them. First, we consider a galaxy-cluster halo populated with subhalos sampled from a realistic subhalo mass function calibrated to N -body simulations. Then, we compare a semianalytical approximation and an adaptive ray-shooting method that we employ to quantify the property of the caustics. As a case study, we investigate Earendel, a z = 6.2 candidate of magnified single- or multiple-star system with a lone lensed image atop the critical curve in the Sunrise Arc. We find that the source size constraint (≲0.3 pc) previously derived from macrolens models should be relaxed by a factor of a few to 10 when subhalos are accounted for, therefore allowing the possibility of a compact star cluster. The subhalos could introduce an astrometric perturbation that is ≲0 \mathop{.}\limits^{\unicode{x02033}} 5, which does not contradict observation. These conclusions are largely robust to changes in the subhalo population. Subhalos therefore should be seriously accounted for when interpreting the astrophysical nature of similar highly magnified sources uncovered in recent high- z observations.}, archive = {J_ApJ}, author = {Lingyuan Ji and Liang Dai}, doi = {10.3847/1538-4357/ada76a}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {190}, shortjournal = {The Astrophys. J.}, title = {Effects of subhalos on interpreting highly magnified sources near lensing caustics}, volume = {980}, year = {2025}, }
• (2025). Modeling the impact of moderate external UV irradiation on disk chemistry. ApJ, 980(2), 189. (www)

  @article{ , abstract = {The chemistry within a protoplanetary disk is greatly affected by external radiation from the local stellar environment. Previous work has focused on extreme radiation fields, representative of the center of something like the Orion Nebula Cluster. However, even in such environments, many disks exist at the edges of a cluster where the lower stellar density leads to radiation fields weaker by orders of magnitude compared to the center. We present new chemical models of a T Tauri disk in the presence of a moderately increased interstellar radiation field (ISRF). Such an environment has a background UV strength 10–100 times higher than the galactic average ISRF. Moderate radiation fields are among the most prevalent disk-harboring environments and have interesting implications for the chemistry of the outer disk radii. We find that the external UV radiation creates an outer ionization front that impacts the cold disk chemistry to varying degrees, depending on outer disk structure. Certain molecules like C + , N 2 H + , C, and CS are more strongly impacted by the ISRF in their abundance, column density, and observable emission. Other abundant species like HCO + and CO are less affected by the external UV flux in the outer disk under such moderate UV conditions. Further, we demonstrate that the chemistry occurring in the inner tens of au is relatively unchanged, which suggests that even in moderately externally irradiated disks the inner disk chemistry may be more similar to isolated disks like those in, e.g., the Taurus and Lupus star-forming regions.}, archive = {J_ApJ}, author = {Rachel E. Gross and L. Ilsedore Cleeves}, doi = {10.3847/1538-4357/ada939}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {189}, shortjournal = {The Astrophys. J.}, title = {Modeling the impact of moderate external UV irradiation on disk chemistry}, volume = {980}, year = {2025}, }
• (2025). Constraints on cosmic-ray acceleration in bright gamma-ray bursts with observations of fermi. ApJ, 980(2), 188. (www)

  @article{ , abstract = {Gamma-ray bursts (GRBs) are widely suggested as potential sources of ultrahigh-energy cosmic rays. The kinetic energy of the jets dissipates, leading to the production of an enormous amount of gamma-ray photons and possibly also the acceleration of protons. The accelerated protons will interact with the radiation of the GRB via the photomeson and Bethe–Heitler processes, which can initiate electromagnetic cascades. This process can give rise to broadband radiation up to the GeV–TeV gamma-ray regime. The expected gamma-ray flux from cascades depends on the properties of the GRB jet, such as the dissipation radius R diss , the bulk Lorentz factor Γ, and the baryon loading factor η p . Therefore, observations of Fermi-LAT can impose constraints on these important parameters. In this study, we select 12 GRBs of high keV–MeV fluence and constrain the baryon loading factor, under different combinations of the bulk Lorentz factor and the dissipation radius based on Fermi-LAT's measurements. Our findings indicate a strong constraint of η p < 10 for most selected GRBs over a large parameter space except for large dissipation radii (≳10 15 cm) and high bulk Lorentz factors (≳600). The constraint is comparable to, and in some GRBs even stronger than, that from high-energy neutrinos for stacked GRBs. Our results suggest that for a typical bulk Lorentz factor of several hundred, the dissipation radii of GRBs need to be large to avoid overshooting the GeV gamma-ray flux during the prompt emission phase of GRBs, which can be used to constrain GRBs.}, archive = {J_ApJ}, author = {Xing-Fu Zhang and Ruo-Yu Liu and Hai-Ming Zhang and Yi-Yun Huang and B. Theodore Zhang and Xiang-Yu Wang}, doi = {10.3847/1538-4357/ada941}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {188}, shortjournal = {The Astrophys. J.}, title = {Constraints on cosmic-ray acceleration in bright gamma-ray bursts with observations of fermi}, volume = {980}, year = {2025}, }
• (2025). Revisiting the fundamental planes of black hole activity for strong jet sources. ApJ, 980(2), 187. (www)

  @article{ , abstract = {Whether the X-ray emissions of strong jet sources originate from disk+coronas or jets is still controversial. In this work, we constructed a strong jet sample containing 50 flat-spectrum radio quasars, 51 low-synchrotron-peaked BL Lac objects, and 18 intermediate-synchrotron-peaked BL Lac objects to explore the origin of X-ray emissions. Generally, blazars are the typical radio-loud active galactic nucleus with a powerful jet toward the observer, causing their broadband emissions to be boosted. By considering the Doppler boosting effect, we obtain the intrinsic radio–X-ray correlation and the fundamental plane (FP) of black hole activity for the strong jet sources: the intrinsic radio–X-ray correlation is {L}_{{\rm{R,int}}}\propto {L}_{{\rm{X,int}}}^{1.04} , which favor the jet-dominated mode; the intrinsic FP is {\rm{log}}\,{L}_{{\rm{R}},{\rm{int}}}=(1.07\pm 0.06)\,{\rm{log}}\,{L}_{{\rm{X}},{\rm{int}}} -(0.22\pm 0.10)\,{\rm{log}}\,{M}_{{\rm{BH}}}-(3.77\pm 2.11) , which can be interpreted by the hybrid mode of jet+standard disk. Our results suggest that the X-ray emissions of strong jet sources are dominated by the jets, but there may also be a small contribution from the disk. In addition, the radio–X-ray correlation and FP of strong jet sources do not have a significant dependence on the Eddington-ratio.}, archive = {J_ApJ}, author = {Qing-Chen Long and Ai-Jun Dong and Qi-Jun Zhi and Lun-Hua Shang}, doi = {10.3847/1538-4357/adaaee}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {187}, shortjournal = {The Astrophys. J.}, title = {Revisiting the fundamental planes of black hole activity for strong jet sources}, volume = {980}, year = {2025}, }
• (2025). Flux-rope-mediated turbulent magnetic reconnection. ApJ, 980(2), 186. (www)

  @article{ , abstract = {We present a new model of magnetic reconnection in the presence of turbulence. The new model differs from the Lazarian–Vishniac turbulent reconnection theory by emphasizing the role of locally coherent magnetic structures, whose existence is shown to be permitted by the properties of magnetic field line separation in turbulent plasma. Local coherence allows storage of magnetic helicity inside the reconnection layer in the form of locally coherent twisted flux ropes. We then introduce the "Alfvén horizon" to explain why the global reconnection rate can be governed by locally coherent magnetic field structure instead of by field line wandering, formally extending to 3D the principle that reconnection can be made fast by fragmentation of the global current layer. Coherence is shown to dominate over field line dispersion if the anisotropy of the turbulence at the perpendicular scale matching the thickness of a marginally stable current layer exceeds the aspect ratio of the current layer. Finally, we conjecture that turbulence generated within the reconnection layer may produce a critically balanced state that maintains the system in the flux-rope-mediated regime. The new model successfully accounts for the major features of 3D numerical simulations of self-generated turbulent reconnection, including reconnection rates of 0.01 in resistive MHD and 0.1 with collisionless physics.}, archive = {J_ApJ}, author = {Alexander J. B. Russell}, doi = {10.3847/1538-4357/adac61}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {186}, shortjournal = {The Astrophys. J.}, title = {Flux-rope-mediated turbulent magnetic reconnection}, volume = {980}, year = {2025}, }
• (2025). Exploring the key features of repeating fast radio bursts with machine learning. ApJ, 980(2), 185. (www)

  @article{ , abstract = {Fast radio bursts (FRBs) are enigmatic high-energy events with unknown origins, which are observationally divided into two categories, i.e., repeaters and nonrepeaters. However, there are potentially a number of nonrepeaters that may be misclassified, as repeating bursts are missed due to the limited sensitivity and observation periods, thus misleading the investigation of their physical properties. In this work, we propose a repeater identification method based on the t-distributed Stochastic Neighbor Embedding algorithm and apply the classification to the first Canadian Hydrogen Intensity Mapping Experiment Fast Radio Burst (CHIME/FRB) catalog. We find that the spectral morphology parameters, specifically spectral running ( r ), represent the key features for identifying repeaters from the nonrepeaters. Also, the results suggest that repeaters are more biased toward narrowband emission, whereas nonrepeaters are inclined toward broadband emission. We provide a list of 163 repeater candidates, five of which are confirmed with an updated repeater catalog from CHIME/FRB. Our findings improve our understanding of the various properties underlying repeaters and nonrepeaters, as well as guidelines for future FRB detection and categorization.}, archive = {J_ApJ}, author = {Wan-Peng Sun and Ji-Guo Zhang and Yichao Li and Wan-Ting Hou and Fu-Wen Zhang and Jing-Fei Zhang and Xin Zhang}, doi = {10.3847/1538-4357/adad6a}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {185}, shortjournal = {The Astrophys. J.}, title = {Exploring the key features of repeating fast radio bursts with machine learning}, volume = {980}, year = {2025}, }
• (2025). A study of cosmological models based on the long gamma-ray burst duration histogram. ApJ, 980(2), 184. (www)

  @article{ , abstract = {The duration of more than one thousand gamma-ray bursts (GRBs) was measured by using the Swift satellite. Besides the redshift distribution of GRBs, the burst duration is another significant property of GRBs that can be analyzed. In this paper, we first find the detection rate of Swift/Burst Alert Telescope for a cosmological model with the ω CDM model. Then, by performing a Monte Carlo simulation, we find the "long" GRB duration histogram to compare the cosmological model with the ω CDM model and the ΛCDM model. The χ 2 minimization method is employed to determine the optimal value of α in the dark energy equation of state, P = cω ( z ) ρ , with ω ( z ) = −1 + α z. We show that for the ωCDM model, all values of α within α = [0, 0.16] range are considered acceptable within two standard deviations.}, archive = {J_ApJ}, author = {Zeinab Kalantari and Sohrab Rahvar}, doi = {10.3847/1538-4357/adad72}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {184}, shortjournal = {The Astrophys. J.}, title = {A study of cosmological models based on the long gamma-ray burst duration histogram}, volume = {980}, year = {2025}, }
• (2025). Insights into galaxy evolution from interpretable sparse feature networks. ApJ, 980(2), 183. (www)

  @article{ , abstract = {Galaxy appearances reveal the physics of how they formed and evolved. Machine learning (ML) models can now exploit galaxies' information-rich morphologies to predict physical properties directly from image cutouts. Learning the relationship between pixel-level features and galaxy properties is essential for building a physical understanding of galaxy evolution, but we are still unable to explicate the details of how deep neural networks represent image features. To address this lack of interpretability, we present a novel neural network architecture called a Sparse Feature Network (SFNet). SFNets produce interpretable features that can be linearly combined in order to estimate galaxy properties like optical emission line ratios or gas-phase metallicity. We find that SFNets do not sacrifice accuracy in order to gain interpretability, and that they perform comparably well to cutting-edge models on astronomical ML tasks. Our novel approach is valuable for finding physical patterns in large data sets and helping astronomers interpret ML results.}, archive = {J_ApJ}, author = {John F. Wu}, doi = {10.3847/1538-4357/adadec}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {183}, shortjournal = {The Astrophys. J.}, title = {Insights into galaxy evolution from interpretable sparse feature networks}, volume = {980}, year = {2025}, }
• (2025). The impact of particle drifts on the flux of high-energy solar protons and he ions arriving at earth from compact solar sources. ApJ, 980(2), 182. (www)

  @article{ , abstract = {We present a numerical model to investigate the role of the ion mass-charge ratio ( m / q ) in determining the flux of MeV–GeV solar energetic particles (SEPs), released impulsively from a compact source near the Sun at 1 au. The equations of motion are numerically integrated for 0.1–1 GeV n −1 H + , 3 He 2+ , and 4 He 2+ test ions as they move in the Parker spiral interplanetary magnetic field (IMF) carried by the solar wind. Pitch-angle scattering is included by using an ad hoc scattering operator, resulting in a parallel mean free path corresponding to "weak" scattering ( λ = 1 au). Our modeled field also includes a flat heliospheric current sheet (HCS) at the ecliptic plane. We consider both A– and A+ IMF polarities and determine the time-flux profile at 1 au, at multiple observation locations, for each ion species and energy. We find that the proximity of the observer to the HCS, magnetic connectivity, and the drifts that depend on kinetic energy, m / q , and IMF polarity strongly impact the resulting flux–time profile. We find significant differences between the onset time, decay time, peak flux, and initial flux of the three ion species at 1 au. This contrast in the decay phase of the three species is evident in the four edges of the magnetically well-connected areas at 1 au. For magnetically poorly connected observers to the source, the onset of the proton flux with respect to that of 3 He 2+ , and 4 He 2+ can be delayed for several hours depending on the observer's relative heliographic latitude and the SEPs' energy.}, archive = {J_ApJ}, author = {Ashraf Moradi and Joe Giacalone}, doi = {10.3847/1538-4357/adadf8}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {182}, shortjournal = {The Astrophys. J.}, title = {The impact of particle drifts on the flux of high-energy solar protons and he ions arriving at earth from compact solar sources}, volume = {980}, year = {2025}, }
• (2025). Spin evolution and mass distribution of galactic binary neutron stars. ApJ, 980(2), 181. (www)

  @article{ , abstract = {Binary neutron stars (BNSs) detected in the Milky Way have total masses distributing narrowly around ∼2.6–2.7 M ⊙ , while the BNS merger GW190425 detected via a gravitational wave has a significantly larger mass (∼3.4 M ⊙ ). This difference is not well understood, yet. In this paper, we investigate the BNS spin evolution via an improved binary star evolution model and its effects on the BNS observability, with the implementation of various relevant astrophysical processes. We find that the first-born neutron star component in low-mass BNSs can be spun up to millisecond pulsars by the accretion of Roche-lobe overflow from its companion and its radio lifetime can be comparable to the Hubble time. However, most high-mass BNSs have substantially shorter radio lifetimes than low-mass BNSs, and thus a smaller probability of being detected via radio emission. Adopting the star formation and metal enrichment history of the Milky Way given by observations, we obtain the survived Galactic BNSs with pulsar components from our population synthesis model and find that their distributions on the diagrams of the spin period versus the spin period time derivative ( P-\dot{P} ) and the orbital period versus the eccentricity ( P orb – e ) can well match those of the observed Galactic BNSs. The total mass distribution of the observed Galactic BNSs can also be matched by the model. A significant fraction (∼19%–22%) of merging BNSs at redshift z ∼ 0 have masses ≳3 M ⊙ , which seems compatible with the GW observations. Future radio observations may detect many more Galactic BNSs, which will put strong constraints on the spin evolution of BNSs during their formation processes.}, archive = {J_ApJ}, author = {Qingbo Chu and Youjun Lu and Shenghua Yu}, doi = {10.3847/1538-4357/ad90e2}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {181}, shortjournal = {The Astrophys. J.}, title = {Spin evolution and mass distribution of galactic binary neutron stars}, volume = {980}, year = {2025}, }
• (2025). Chemically self-consistent modeling of the globular cluster NGC 2808 and its effects on the inferred helium abundance of multiple stellar populations. ApJ, 980(2), 180. (www)

  @article{ , abstract = {The helium abundances in the multiple populations that are now known to comprise all closely studied Milky Way globular clusters (GCs) are often inferred by fitting isochrones generated from stellar evolutionary models to GC photometry. It is therefore important to build stellar models that are chemically self-consistent in terms of their structure, atmosphere, and opacity. In this work we present the first chemically self-consistent stellar models of the Milky Way GC NGC 2808 using MARCS model atmospheres, OPLIB high-temperature radiative opacities, and AESOPUS low-temperature radiative opacities. These stellar models were fit to the NGC 2808 photometry using Fidanka , a new software tool that was developed to optimally fit cluster photometry to isochrones and for population synthesis. Fidanka can determine, in a relatively unbiased way, the ideal number of distinct populations that exist within a data set and then fit isochrones to each population. We achieve this outcome through a combination of Bayesian Gaussian mixture modeling and a novel number density estimation algorithm. Using Fidanka and F275W – F814W photometry from the Hubble UV Globular Cluster Survey, we find that the helium abundance of the second generation of stars in NGC 2808 is higher than the first generation by 15% ± 3%. This is in agreement with previous studies of NGC 2808. This work, along with previous work by A. Dotter et al. focused on NGC 6752, demonstrates that chemically self-consistent models of GCs do not significantly alter inferred helium abundances and are therefore unlikely to be worth the significant additional time investment.}, archive = {J_ApJ}, author = {Emily M. Boudreaux and Brian C. Chaboyer and Amanda Ash and Renata Edaes Hoh and Gregory Feiden}, doi = {10.3847/1538-4357/ad9740}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {180}, shortjournal = {The Astrophys. J.}, title = {Chemically self-consistent modeling of the globular cluster NGC 2808 and its effects on the inferred helium abundance of multiple stellar populations}, volume = {980}, year = {2025}, }
• (2025). Planets around solar Twins/Analogs (PASTA). i. high-precision stellar chemical abundances for 17 planet-hosting stars and the condensation temperature trend*. ApJ, 980(2), 179. (www)

  @article{ , abstract = {The Sun is depleted in refractory elements compared to nearby solar twins, which may be linked to the formation of giant or terrestrial planets. Here we present high-resolution, high signal-to-noise spectroscopic data for 17 solar-like stars hosting planets, obtained with Magellan II/MIKE, to investigate whether this depletion is related to planet formation. We derive stellar parameters, including stellar atmosphere, age, radius, mass, and chemical abundances for 22 elements from carbon to europium through line-by-line differential analysis. Our uncertainties range from 0.01 dex for Fe and Si to 0.08 dex for Sr, Y, and Eu. By comparing the solar abundances to those of the 17 stars, we investigate the differential abundance ([X/Fe] solar –[X/Fe] star ) versus condensation temperature ( T c ) trend. In particular, we apply Galactic chemical evolution corrections to five solar twins within the full sample. Our results conform to previous studies that the Sun is relatively depleted in refractory compared to volatile elements. For both five solar twins and the rest of the solar-like stars, we find that all stars hosting known gas giant planets exhibit negative T c trend slopes, suggesting that the Sun is relatively depleted in refractory elements compared to similar giant planet-hosting stars. Additionally, we find no correlation between T c trend slopes and the total mass of detected terrestrial planets in each system, suggesting that terrestrial planet formation may not be the cause of refractory element depletion in the Sun.}, archive = {J_ApJ}, author = {Qinghui Sun and Sharon Xuesong Wang and Tianjun Gan and Chenyang Ji and Zitao Lin and Yuan-Sen Ting and Johanna Teske and Haining Li and Fan Liu and Xinyan Hua and Jiaxin Tang and Jie Yu and Jiayue Zhang and Mariona Badenas-Agusti and Andrew Vanderburg and George R. Ricker and Roland Vanderspek and David W. Latham and Sara Seager and Jon M. Jenkins and Richard P. Schwarz and Tristan Guillot and Thiam-Guan Tan and Dennis M. Conti and Kevin I. Collins and Gregor Srdoc and Chris Stockdale and Olga Suarez and Roberto Zambelli and Don Radford and Khalid Barkaoui and Phil Evans and Allyson Bieryla}, doi = {10.3847/1538-4357/ad9924}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {179}, shortjournal = {The Astrophys. J.}, title = {Planets around solar Twins/Analogs (PASTA). i. high-precision stellar chemical abundances for 17 planet-hosting stars and the condensation temperature trend*}, volume = {980}, year = {2025}, }
• (2025). Toward early-type eclipsing binaries as extragalactic milestones. IV. physical properties of three detached O/B-type systems in the LMC. ApJ, 980(2), 178. (www)

  @article{ , abstract = {We present a complete set of physical parameters for three early-type eclipsing binary systems in the Large Magellanic Cloud (LMC): OGLE LMC-ECL-17660, OGLE LMC-ECL-18794, and HV 2274, together with the orbital solutions. The first and third systems comprise B-type stars, while the second has O-type components and exhibits a total eclipse. We performed a complex analysis that included modeling light and radial velocity curves, O − C analysis, and additional non-LTE spectroscopic analysis for the O-type system. We found that OGLE LMC-ECL-17660 is at least a triple, and tentatively, a quadruple. A significant nonlinear period decrease was determined for HV 2274. Its origin is unclear, possibly due to a faint, low-mass companion on a wide orbit. The analyzed components have masses ranging from 11.7 M ⊙ to 22.1 M ⊙ , radii from 7.0 R ⊙ to 14.2 R ⊙ , and temperatures between 22,500 and 36,000 K. For HV 2274, the precision of our masses and radii is about six times higher than in previous studies. The position of the components of all six systems analyzed in this series on the mass–luminosity and mass–radius diagrams indicates they are evolutionarily advanced on the main sequence. Our sample contributes significantly to the knowledge of physical parameters of early-type stars in the mass range of 11 M ⊙ –23 M ⊙ . A new mass–luminosity relation for O- and B-type stars in the LMC is provided. Additionally, we used the measured apsidal motion of the systems to compare the observational and theoretical internal structure constant.}, archive = {J_ApJ}, author = {Mónica Taormina and G. Pietrzyński and R.-P. Kudritzki and B. Pilecki and I. B. Thompson and J. Puls and M. Górski and B. Zgirski and D. Graczyk and M. A. Urbaneja and W. Gieren and W. Narloch and G. Hajdu}, doi = {10.3847/1538-4357/ad9dda}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {178}, shortjournal = {The Astrophys. J.}, title = {Toward early-type eclipsing binaries as extragalactic milestones. IV. physical properties of three detached O/B-type systems in the LMC}, volume = {980}, year = {2025}, }
• (2025). Prediction of star formation rates using an artificial neural network. ApJ, 980(2), 177. (www)

  @article{ , abstract = {In this study we develop an artificial neural network to estimate the infrared (IR) luminosity and star formation rates (SFR) of galaxies. Our network is trained using "true" IR luminosity values derived from modeling the IR spectral energy distributions of FIR-detected galaxies. We explore five different sets of input features, each incorporating optical, mid-infrared, near-infrared, ultraviolet, and emission line data, along with spectroscopic redshifts and uncertainties. All feature sets yield similar IR luminosity predictions, but including all photometric data leads to slightly improved performance. This suggests that comprehensive photometric information enhances the accuracy of our predictions. Our network is applied to a sample of SDSS galaxies defined as unseen data, and the results are compared with three published catalogs of SFRs. Overall, our network demonstrates excellent performance for star-forming galaxies, while we observe discrepancies in composite and AGN samples. These inconsistencies may stem from uncertainties inherent in the compared catalogs or potential limitations in the performance of our network.}, archive = {J_ApJ}, author = {Ashraf Ayubinia and Jong-Hak Woo and Fatemeh Hafezianzadeh and Taehwan Kim and Changseok Kim}, doi = {10.3847/1538-4357/ada366}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {177}, shortjournal = {The Astrophys. J.}, title = {Prediction of star formation rates using an artificial neural network}, volume = {980}, year = {2025}, }
• (2025). Flat U-net: An efficient ultralightweight model for solar filament segmentation in full-disk hα images. ApJ, 980(2), 176. (www)

  @article{ , abstract = {Solar filaments are one of the most prominent features observed on the Sun, and their evolutions are closely related to various solar activities, such as flares and coronal mass ejections. Real-time automated identification of solar filaments is the most effective approach to managing large volumes of data. Existing models of filament identification are characterized by large parameter sizes and high computational costs, which limit their future applications in highly integrated and intelligent ground-based and space-borne observation devices. Consequently, the design of more lightweight models will facilitate the advancement of intelligent observation equipment. In this study, we introduce Flat U-Net, a novel and highly efficient ultralightweight model that incorporates simplified channel attention (SCA) and channel self-attention (CSA) convolutional blocks for the segmentation of solar filaments in full-disk H α images. Feature information from each network layer is fully extracted to reconstruct interchannel feature representations. Each block effectively optimizes the channel features from the previous layer, significantly reducing parameters. The network architecture presents an elegant flattening, improving its efficiency, and simplifying the overall design. Experimental validation demonstrates that a model composed of pure SCAs achieves a precision of approximately 0.93, with dice similarity coefficient (DSC) and recall rates of 0.76 and 0.64, respectively, significantly outperforming the classical U-Net. Introducing a certain number of CSA blocks improves the DSC and recall rates to 0.82 and 0.74, respectively, which demonstrates a pronounced advantage, particularly concerning model weight size and detection effectiveness. The data set, models, and code are available as open-source resources.}, archive = {J_ApJ}, author = {GaoFei Zhu and GangHua Lin and Xiao Yang and Cheng Zeng}, doi = {10.3847/1538-4357/adadff}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {176}, shortjournal = {The Astrophys. J.}, title = {Flat U-net: An efficient ultralightweight model for solar filament segmentation in full-disk hα images}, volume = {980}, year = {2025}, }
• (2025). Estimating the mass escaping rates of radius-valley-spanning planets in the TOI-431 system via X-ray and ultraviolet evaporation. ApJ, 980(2), 175. (www)

  @article{ , abstract = {The TOI-431 system has three close-in exoplanets, which gives an ideal lab to study gas escape. In this study, we measure the X-ray and ultraviolet luminosity for TOI-431 with XMM-Newton's European Photon Imaging Camera-pn and Optical/UV Monitor Telescope data, then calculate the fluxes for the planets in the system. We find TOI-431 b's {F}_{\mathrm{XUV},{\rm{b}}}=70,{286}_{-2611}^{+12,060}\,\mathrm{erg}\,{\mathrm{cm}}^{-2}\,{{\rm{s}}}^{-1} is 75 times TOI-431 d's {F}_{\mathrm{XUV},{\rm{d}}}={935}_{-35}^{+160}\,\mathrm{erg}\,{\mathrm{cm}}^{-2}\,{{\rm{s}}}^{-1} . Adopting the energy limit method and hydrodynamic code ATES with a set of He/H ratios, we obtain mass-loss rates of {10}^{10.{51}_{\mathrm{-0.02}}^{\mathrm{+0.07}}} g s −1 for TOI-431 b and {10}^{9.{14}_{-0.02}^{+0.07}} and 10 9.84 ∼9.94 g s −1 for TOI-431 d. We predict 2.93% ∼ 7.91% H i Ly α and 0.19% ∼ 10.65% He i triplet absorption depths for TOI-431 d; thus, its gas escaping is detectable in principle. For both TOI-431 b and d, we select similar planets from the New Generation Planetary Population Synthesis data. They show that, considering the mass-loss rates, TOI-431 b should be a naked solid planet, and TOI-431 d will likely maintain its gas envelope until the host star dies. According to the formation and evolution tracks, we find that TOI-431 b's potential birthplace (0.1–2 au) should be further in than TOI-431 d's (2–12 au). Our results are consistent with the interpretation of the radius valley being caused by atmospheric escape. The intrinsic reason may be their birthplace, which will determine how close they can migrate to the host star, then lose mass and result in the Fulton gap.}, archive = {J_ApJ}, author = {Xiaoming Jiang and Jonathan H. Jiang and Remo Burn and Zong-Hong Zhu}, doi = {10.3847/1538-4357/ada607}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {175}, shortjournal = {The Astrophys. J.}, title = {Estimating the mass escaping rates of radius-valley-spanning planets in the TOI-431 system via X-ray and ultraviolet evaporation}, volume = {980}, year = {2025}, }
• (2025). Comprehensive parameter determination of exoplanets through asteroseismic host star constraints. ApJ, 980(2), 174. (www)

  @article{ , abstract = {This study develops a robust framework for exoplanet characterization by leveraging asteroseismic constraints on host stars. Using precise photometric data from missions such as Kepler and TESS, we derive stellar parameters, including mass, radius, and age, with high accuracy through asteroseismic analysis. These stellar parameters are incorporated as priors in a Bayesian framework to refine planetary properties such as the mass, radius, and orbital parameters. By applying Markov Chain Monte Carlo methods, we extract posterior distributions of planetary parameters, achieving significant improvements in precision and reliability. This approach is particularly effective for systems with evolved host stars, where precise stellar properties are essential for resolving uncertainties in planetary characterization. The results demonstrate the importance of asteroseismology in bridging stellar astrophysics and exoplanet science, enabling detailed studies of planetary system architectures and their dependence on host star properties. Our methodology underscores the synergy between stellar and planetary studies, paving the way for future research on exoplanet populations. This work provides a foundation for utilizing data from upcoming missions like PLATO, ensuring continued advancements in the precision and scope of exoplanet characterization.}, archive = {J_ApJ}, author = {Wen-Xu Lin and Sheng-Bang Qian and Li-Ying Zhu and Wen-Ping Liao and Fu-Xing Li and Xiang-Dong Shi and Lin-Jia Li and Er-Gang Zhao}, doi = {10.3847/1538-4357/ada60b}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {174}, shortjournal = {The Astrophys. J.}, title = {Comprehensive parameter determination of exoplanets through asteroseismic host star constraints}, volume = {980}, year = {2025}, }
• (2025). Solar variability in the mg ii h and k lines. ApJ, 980(2), 173. (www)

  @article{ , abstract = {Solar irradiance and its variations in the ultraviolet (UV) control the photochemistry in Earth's atmosphere and influence Earth's climate. The variability in the Mg ii h and k core-to-wing ratio, also known as the Mg ii index, is highly correlated with the solar UV irradiance variability. Because of this, the Mg ii index is routinely used as a proxy for solar UV irradiance variability, which can help to get insights into the influence of solar UV irradiance variability on Earth's climate. Measurements of the Mg ii index, however, have only been carried out since 1978 and do not cover climate-relevant timescales longer than a few decades. Here we present a model to calculate the Mg ii index and its variability based on the well-established Spectral And Total Irradiance REconstruction (SATIRE) model. We demonstrate that our model calculations yield an excellent agreement with the observed Mg ii index variations, both on the solar activity cycle and on the solar rotation timescales. Using this model, we synthesize the Mg ii index time series on climate-relevant timescales of decades and longer. Here we present the time series of the Mg ii index spanning nearly three centuries.}, archive = {J_ApJ}, author = {K. Sowmya and M. Snow and A. I. Shapiro and N. A. Krivova and T. Chatzistergos and S. K. Solanki}, doi = {10.3847/1538-4357/ada6af}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {173}, shortjournal = {The Astrophys. J.}, title = {Solar variability in the mg ii h and k lines}, volume = {980}, year = {2025}, }
• (2025). LensWatch. II. improved photometry and time-delay constraints on the strongly lensed type ia supernova 2022qmx (“SN zwicky”) with hubble space telescope template observations. ApJ, 980(2), 172. (www)

  @article{ , abstract = {Strongly lensed supernovae (SNe) are a rare class of transient that can offer tight cosmological constraints that are complementary to methods from other astronomical events. We present a follow-up study of one recently discovered strongly lensed SN, the quadruply imaged type Ia SN 2022qmx (aka "SN Zwicky"), at z = 0.3544. We measure updated, template-subtracted photometry for SN Zwicky and derive improved time delays and magnifications. This is possible because SNe are transient, fading away after reaching their peak brightness. Specifically, we measure point-spread-function photometry for all four images of SN Zwicky in three Hubble Space Telescope WFC3/UVIS passbands (F475W, F625W, and F814W) and one WFC3/IR passband (F160W), with template images taken ∼11 months after the epoch in which the SN images appear. We find consistency to within 2 σ between lens-model-predicted time delays (≲1 day) and measured time delays with HST colors (≲2 days), including the uncertainty from chromatic microlensing that may arise from stars in the lensing galaxy. The standardizable nature of SNe Ia allows us to estimate absolute magnifications for the four images, with images A and C being elevated in magnification compared to lens model predictions by about 6 σ and 3 σ , respectively, confirming previous work. We show that millilensing or differential dust extinction is unable to explain these discrepancies, and we find evidence for the existence of microlensing in images A, C, and potentially D that may contribute to the anomalous magnification.}, archive = {J_ApJ}, author = {C. Larison and J. D. R. Pierel and M. J. B. Newman and S. W. Jha and D. Gilman and E. E. Hayes and A. Agrawal and N. Arendse and S. Birrer and M. Bronikowski and S. Chakrabarti and J. M. Della Costa and D. A. Coulter and F. Courbin and K. A. Dalrymple and S. Dhawan and J. M. Diego and C. Gall and A. Goobar and J. Hjorth and X. Huang and J. Johansson and S. Mao and R. Marques-Chaves and P. A. Mazzali and A. More and L. A. Moustakas and I. Pérez-Fournon and T. Petrushevska and F. Poidevin and A. Rest and A. J. Shajib and R. Shirley and L. G. Strolger and S. H. Suyu and T. Treu and Y. Zenati}, doi = {10.3847/1538-4357/ada776}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {172}, shortjournal = {The Astrophys. J.}, title = {LensWatch. II. improved photometry and time-delay constraints on the strongly lensed type ia supernova 2022qmx (“SN zwicky”) with hubble space telescope template observations}, volume = {980}, year = {2025}, }
• (2025). MUSEQuBES: Connecting h i absorption with lyα emitters at z ≈ 3.3. ApJ, 980(2), 171. (www)

  @article{ , abstract = {We present a comprehensive analysis of H i absorption around 96 Ly α emitters (LAEs) at z ≈ 3.3 (median Ly α luminosity ≈10 42 erg s −1 ). These LAEs were identified within eight MUSE fields, each 1^{\prime} \times 1^{\prime} on the sky and centered on a bright background quasar, as part of the MUSEQuBES survey. Using Voigt profile fitting for all H i absorbers detected within ±​​​​​​500 km s −1 of these LAEs, we compiled a catalog of 800 H i absorption components. Our analysis shows that H i absorption is enhanced near the LAEs compared to the intergalactic medium. However, no trend is found between the column densities of H i absorbers and their impact parameters from the LAEs (spanning ​​​​​​≈54–260 pkpc). Additionally, all galaxies associated with Lyman-limit systems have impact parameters >50 pkpc from the quasar sightlines, suggesting that true absorber hosts may be too faint to detect. The LAEs show an overall H i covering fraction ( f c (H i )) of ≈88% for a threshold {{\rm{log}}}_{10}(N/{{\rm{cm}}}^{-2}) (H i ) = 15. Notably, at the same threshold, the LAEs in pairs/groups exhibit a 100% H i covering fraction out to ≈250 pkpc. In contrast, isolated LAEs consistently show a lower f c (H i ) of ≈80%. This environmental influence on f c (H i ) is also evident up to ≈300 km s −1 in differential bins of line-of-sight velocity. We find an anticorrelation between f c (H i ) and the equivalent width of rest-frame Ly α emission (EW 0 ). Based on the Ly α shell model, this could imply that gas-rich galaxies tend to reside in gas-rich environments or that the LAEs with higher EW 0 are more efficient at ionizing their surrounding medium.}, archive = {J_ApJ}, author = {Eshita Banerjee and Sowgat Muzahid and Joop Schaye and Jérémy Blaizot and Nicolas Bouché and Sebastiano Cantalupo and Sean D. Johnson and Jorryt Matthee and Anne Verhamme}, doi = {10.3847/1538-4357/ada7e9}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {171}, shortjournal = {The Astrophys. J.}, title = {MUSEQuBES: Connecting h i absorption with lyα emitters at z ≈ 3.3}, volume = {980}, year = {2025}, }
• (2025). Hubble space telescope observations within the sphere of influence of the powerful supermassive black hole in PKS 0745-191. ApJ, 980(2), 170. (www)

  @article{ , abstract = {We present Space Telescope Imaging Spectrograph observations from the Hubble Space Telescope of the supermassive black hole (SMBH) at the center of PKS 0745-191, a brightest cluster galaxy (BCG) undergoing powerful radio-mode active galactic nucleus (AGN) feedback ( P cav ~ 5 × 10 45 erg s −1 ). These high-resolution data offer the first spatially resolved map of gas dynamics within an SMBH's sphere of influence under such powerful feedback. Our results reveal the presence of highly chaotic, nondrotational ionized gas flows on subkiloparsec scales, in contrast to the more coherent flows observed on larger scales. While radio-mode feedback effectively thermalizes hot gas in galaxy clusters on kiloparsec scales, within the core, the hot gas flow may decouple, leading to a reduction in angular momentum and supplying ionized gas through cooling, which could enhance accretion onto the SMBH. This process could, in turn, lead to a self-regulating feedback loop. Compared to other BCGs with weaker radio-mode feedback, where rotation is more stable, intense feedback may lead to more chaotic flows, indicating a stronger coupling between jet activity and gas dynamics. Additionally, we observe a sharp increase in velocity dispersion near the nucleus, consistent with a very massive M BH ~ 1.5 × 10 10 M ⊙ SMBH. The density profile of the ionized gas is also notably flat, paralleling the profiles observed in X-ray gas around galaxies where the Bondi radius is resolved. These results provide valuable insights into the complex mechanisms driving galaxy evolution, highlighting the intricate relationship between SMBH fueling and AGN feedback within the host galaxy.}, archive = {J_ApJ}, author = {Julie Hlavacek-Larrondo and Hyunseop Choi and Minghao Guo and Annabelle Richard-Laferrière and Carter Rhea and Marine Prunier and Helen Russell and Andy Fabian and Jonelle L. Walsh and Marie-Joëlle Gingras and Brian McNamara and Steve Allen and André-Nicolas Chené and Alastair Edge and Marie-Lou Gendron-Marsolais and Michael McDonald and Priyamvada Natarajan and Jeremy Sanders and James F. Steiner and Benjamin Vigneron and Anja von der Linden}, doi = {10.3847/1538-4357/ada7ed}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {170}, shortjournal = {The Astrophys. J.}, title = {Hubble space telescope observations within the sphere of influence of the powerful supermassive black hole in PKS 0745-191}, volume = {980}, year = {2025}, }
• (2025). The secondary component of the extremely low mass ratio massive binary HD 165246 revealed by GHOST. ApJ, 980(2), 169. (www)

  @article{ , abstract = {In the pursuit of understanding the multiplicity of massive stars, the OWN Survey has undertaken spectroscopic monitoring of hundreds of targets over the past 20 yr. This effort has led to the discovery of new single-lined spectroscopic binaries. Characterizing the unseen companions of these systems is crucial to deriving precise stellar parameters, including the mass of each component, and constraining formation models for massive binary systems. In this paper, we aim to physically and evolutionarily characterize the stellar components of the massive binary HD 165246. We analyzed spectra obtained by the OWN Survey and used Kepler's second mission (K2) photometry, from which we determined the physical parameters of the system. Thanks to the high-resolution capabilities of the new echelle spectrograph Gemini/GHOST, we could directly detect spectral features of the secondary component for the first time. A very low mass ratio for the system is confirmed ( q ~ 0.16), making this binary one of the few extremely low mass ratio systems known. The primary star has a mass of M a = 22 ± 1 M ⊙ and a radius of R a = 7.0 ± 0.1 R ⊙ , while the secondary star has a mass of M b = 3.4 ± 0.1 M ⊙ and a radius of R b = 2.22 ± 0.02 R ⊙ . Stellar evolution models indicate that the system has undergone approximately two million years of evolution since its formation. Moreover, the secondary star is identified as a pre-main-sequence object, progressing toward the zero-age main sequence. This paper illustrates the power of high-resolution spectrographs such as GHOST in finding much lower mass, previously unseen stellar components of binary star systems.}, archive = {J_ApJ}, author = {C. N. Rodriguez and T. Ansin and G. A. Ferrero and O. G. Benvenuto and R. Gamen and N. I. Morrell and J. I. Arias and R. E. Higa and C. Putkuri and C. Johnston and K. Chiboucas and E. Deibert and C. R. Hayes and J.-E. Heo and M. Jeong and V. Kalari and E. Martioli and V. M. Placco and K. A. Venn and S. Xu and R. Diaz and M. Gomez-Jimenez and R. Ruiz-Carmona and C. Simpson and A. W. McConnachie and J. Pazder and G. Burley and T. A. M. Berg and J. G. Robertson and K. Labrie and J. Thomas-Osip}, doi = {10.3847/1538-4357/ada892}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {169}, shortjournal = {The Astrophys. J.}, title = {The secondary component of the extremely low mass ratio massive binary HD 165246 revealed by GHOST}, volume = {980}, year = {2025}, }
• (2025). Improved SED-fitting assumptions result in inside-out quenching at z ~ 0.5 and quenching at all radii simultaneously at z ~ 1. ApJ, 980(2), 168. (www)

  @article{ , abstract = {Many studies conclude that galaxies quench from the inside-out by examining profiles of specific star formation rate (sSFR). These are usually measured by fitting spectral energy distributions (SEDs) assuming a fixed dust law and uniform priors on all parameters. Here, we examine the effects of more physically motivated priors: a flexible dust law, an exponential prior on the dust attenuation A V , and Gaussian priors that favor extended star formation histories. This results in model colors that better trace observations. We then perform radial SED fits to multiband flux profiles measured from Hubble Space Telescope images for 1440 galaxies at 0.4 < z < 1.5 of stellar masses 10 10 –10 11.5 M ⊙ using both the traditional and the more physically motivated assumptions. The latter results in star formation rate and A V profiles that agree with measurements from spectroscopy and A V profiles that behave correctly as a function of inclination. Since green valley galaxies at z ∼ 1.3 are expected to evolve into quiescent galaxies at z ∼ 0.9, we compare their sSFR profiles using the more physically motivated assumptions. Their slopes are similar at all masses (0.06–0.08 dex kpc −1 ), and the normalizations for the quiescent galaxies are lower. Therefore, the sSFR profiles decline with time as quenching occurs at all radii simultaneously. We compare profiles of green valley galaxies at z ∼ 0.9 and quiescent galaxies at z ∼ 0.5. The former are shallower at all masses by ~0.1 dex kpc −1 . The sSFR profiles steepen with time as galaxies quench from the inside-out. In summary, galaxies at z ∼ 1 quench at all radii simultaneously while galaxies at z ∼ 0.7 quench from the inside-out.}, archive = {J_ApJ}, author = {Alexander de la Vega and Susan A. Kassin and Camilla Pacifici and Stéphane Charlot and Emma Curtis-Lake and Jacopo Chevallard and Timothy M. Heckman and Anton M. Koekemoer and Weichen Wang}, doi = {10.3847/1538-4357/ada8a2}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {168}, shortjournal = {The Astrophys. J.}, title = {Improved SED-fitting assumptions result in inside-out quenching at z ~ 0.5 and quenching at all radii simultaneously at z ~ 1}, volume = {980}, year = {2025}, }
• (2025). Nonthermal signatures of radiative supernova remnants. II. the impact of cosmic rays and magnetic fields. ApJ, 980(2), 167. (www)

  @article{ , abstract = {Near the ends of their lives, supernova remnants (SNRs) enter a "radiative phase," when efficient cooling of the postshock gas slows expansion. Understanding SNR evolution at this stage is crucial for estimating feedback in galaxies, as SNRs are expected to release energy and momentum into the interstellar medium near the ends of their lives. A standard prediction of SNR evolutionary models is that the onset of the radiative stage precipitates the formation of a dense shell behind the forward shock. In Paper I, we showed that such shell formation yields detectable nonthermal radiation from radio to γ -rays, most notably emission brightening by nearly 2 orders of magnitude. However, there remains no observational evidence for such brightening, suggesting that this standard prediction needs to be investigated. In this paper, we perform magnetohydrodynamic simulations of SNR evolution through the radiative stage, including cosmic rays (CRs) and magnetic fields to assess their dynamical roles. We find that both sources of nonthermal pressure impede shell formation, reducing shell densities by a factor of a few to more than an order of magnitude. We also use a self-consistent model of particle acceleration to estimate the nonthermal emission from these modified SNRs and demonstrate that, for reasonable CR acceleration efficiencies and magnetic field strengths, the nonthermal signatures of shell formation can all but disappear. We therefore conclude that the absence of observational signatures of shell formation represents strong evidence that nonthermal pressures from CRs and magnetic fields play a critical dynamical role in late-stage SNR evolution.}, archive = {J_ApJ}, author = {Rebecca Diesing and Siddhartha Gupta}, doi = {10.3847/1538-4357/ada93d}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {167}, shortjournal = {The Astrophys. J.}, title = {Nonthermal signatures of radiative supernova remnants. II. the impact of cosmic rays and magnetic fields}, volume = {980}, year = {2025}, }
• (2025). Magnetized protoplanetary disks around young stars in the presence of realistic cooling. ApJ, 980(2), 166. (www)

  @article{ , abstract = {In this paper, we study the effects of magnetic fields and ohmic resistivity on the structure of protoplanetary disks (PPDs) in the presence of realistic radiative cooling. We use the self-similar method to solve the magnetohydrodynamic equations in spherical coordinates ( r , θ , ϕ ). Our solutions indicate that a strong magnetic field reduces the outflow region while increasing the mass accretion rate, which in turn leads to a thicker disk. Our model applied to the FU Orionis PPD indicates that in the inner regions of the disk ( r = 10 au), \dot{M} is the order of \dot{M}\approx 5\times 1{0}^{-4}{M}_{\odot }\,{\mathrm{yr}}^{-1} and the mass outflow rate is {\dot{M}}_{w}=0.1{\dot{M}}_{\mathrm{acc}} , which is consistent with the observed range of accretion rates. Additionally, we calculated the cooling timescale in our model to assess one possible fragmentation condition necessary for planet formation. Our results indicate that, although the gravitational instability condition exists in the midplane of the disk, the cooling timescale is not short enough ( τ cool ≈ 1000Ω −1 ), and one possible mechanism for planet formation is not met.}, archive = {J_ApJ}, author = {Hanifeh Ghanbarnejad and Maryam Ghasemnezhad}, doi = {10.3847/1538-4357/ada93f}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {166}, shortjournal = {The Astrophys. J.}, title = {Magnetized protoplanetary disks around young stars in the presence of realistic cooling}, volume = {980}, year = {2025}, }
• (2025). Bayesian pulsar timing and noise analysis with vela.jl: An overview. ApJ, 980(2), 165. (www)

  @article{ , abstract = {We present Vela.jl , an efficient, modular, easy-to-use Bayesian pulsar timing and noise analysis package written in Julia. Vela.jl provides an independent, efficient, and parallelized implementation of the full nonlinear pulsar timing and noise model along with a Python binding named pyvela . One-time operations such as data file input, clock corrections, and solar system ephemeris computations are performed by pyvela with the help of the PINT pulsar timing package. Its reliability is ensured via careful design utilizing Julia's type system, strict version control, and an exhaustive test suite. This paper describes the design and usage of Vela.jl focusing on the narrowband paradigm.}, archive = {J_ApJ}, author = {Abhimanyu Susobhanan}, doi = {10.3847/1538-4357/adaaec}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {165}, shortjournal = {The Astrophys. J.}, title = {Bayesian pulsar timing and noise analysis with vela.jl: An overview}, volume = {980}, year = {2025}, }
• (2025). Search for neutrino signals correlated with LHAASO diffuse galactic emission. ApJ, 980(2), 164. (www)

  @article{ , abstract = {The diffuse Galactic γ -ray emission originates from the interactions between cosmic rays and the interstellar medium or radiation fields within our Galaxy, where the production of neutrinos is also anticipated. Recently, the Large High Altitude Air Shower Observatory (LHAASO) reported measurements of diffuse γ -rays from the Galactic plane with energies ranging from sub-TeV to 1 PeV. Using 7 yr of publicly available IceCube track data with the full detector, we conduct a template search using the γ -ray flux map observed by LHAASO-KM2A as the neutrino emission template and perform a scan search of the Galactic plane. In the template search, a mild excess of neutrinos is observed in the Galactic plane with a pretrial (posttrial) significance of 1.9 σ (1.1 σ ). The measured muon neutrino intensity at 25 TeV is 4.7{3}_{-2.51}^{+2.53}\times 1{0}^{-14}\,{{\rm{TeV}}}^{-1}\,{{\rm{cm}}}^{-2}\,{{\rm{s}}}^{-1}\,{{\rm{sr}}}^{-1} , consistent with the expected neutrino flux assuming that all the diffuse Galactic γ -rays originate from hadronic interactions. In the Galactic plane scan search, the most significant location is found at l = 63 \mathop{.}\limits^{\unicode{x000B0}} 57 and b = 0 \mathop{.}\limits^{\unicode{x000B0}} 93 with a pretrial (posttrial) significance of 4.6 σ (1.8 σ ).}, archive = {J_ApJ}, author = {Wenlian Li and Tian-Qi Huang and Donglian Xu and Huihai He}, doi = {10.3847/1538-4357/adabe8}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {164}, shortjournal = {The Astrophys. J.}, title = {Search for neutrino signals correlated with LHAASO diffuse galactic emission}, volume = {980}, year = {2025}, }
• (2025). Toward high-order solar corona simulations: A high-order hyperbolized poisson approach for magnetic field initialization. ApJ, 980(2), 163. (www)

  @article{ , abstract = {Proper initialization of the solar corona magnetic field is important for easing the iterative process of realistic and efficient global magnetohydrodynamics (MHD) simulations. This study introduces a high-order flux reconstruction (FR) framework for solving the Poisson equation, a necessary step for computing a potential-field source-surface (PFSS) to initialize the magnetic field for global solar corona simulations with MHD. By hyperbolizing the elliptic Poisson equation into a set of hyperbolic equations, we develop an efficient and robust high-order PFSS solver. Our contributions include developing a Q 2 (i.e., quadratic) geometrical representation using prismatic elements for the computational domain, which enables high-order mesh generation. Such a hyperbolized Poisson solver effectively relaxes magnetic fields extrapolated from solar magnetograms, producing scalar potential fields that align well with theoretical expectations. Extensive verification was conducted on the high-order FR solver for polynomial orders up to P 3, achieving fourth-order spatial accuracy. The hyperbolized solver demonstrates comparable accuracy to reference solutions (both analytical and numerical) while offering efficient performance, particularly on coarser meshes, making it competitive with state-of-the-art low-order finite volume solvers, which are mostly used for solar MHD simulations. The described developments are a milestone for enabling high-order global solar corona simulations on 3D unstructured grids.}, archive = {J_ApJ}, author = {Rayan Dhib and Firas Ben Ameur and Vatsalya Sharma and Andrea Lani and Stefaan Poedts}, doi = {10.3847/1538-4357/adace5}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {163}, shortjournal = {The Astrophys. J.}, title = {Toward high-order solar corona simulations: A high-order hyperbolized poisson approach for magnetic field initialization}, volume = {980}, year = {2025}, }
• (2025). ASKAP observations of the radio shell in the composite supernova remnant g310.6-1.6. ApJ, 980(2), 162. (www)

  @article{ , abstract = {We report the observations of the radio shell of the supernova remnant (SNR) G310.6–1.6 at 943 MHz from the Evolutionary Map of the Universe (EMU) and the Polarization Sky Survey of the Universe's Magnetism (POSSUM) surveys by using the Australian Square Kilometre Array Pathfinder (ASKAP). We detect polarized emission from the central pulsar wind nebula (PWN) with rotation measures varying from –696 rad m −2 to –601 rad m −2 . We measure the integrated flux density of the shell to be 36.4 ± 2.2 mJy at 943 MHz and derive a spectral index of α pwn = −0.4 ± 0.1 for the PWN and α shell = −0.7 ± 0.3 for the SNR shell. From the combined radio and X-ray observations, the object can be identified as a supernova explosion of about 2500 yr ago with an energy of about 1.3 × 10 50 erg, suggesting an ejected mass of about 10 M ⊙ . The circular radio shell outside the circular hard X-ray shell is unique among Galactic SNRs. We discuss several possible scenarios, including blast wave, reverse shock, and pulsar-fed emission, but find that none of them can fully explain the observed characteristics of the shell. This poses a challenge for understanding the evolution of SNRs. The results of this paper demonstrate the potential of the ASKAP EMU and POSSUM surveys to discover more objects of small angular size and low surface brightness.}, archive = {J_ApJ}, author = {Wenhui Jing and Jennifer L. West and Xiaohui Sun and Wasim Raja and Xianghua Li and Lingxiao Dang and Ping Zhou and Miroslav D. Filipović and Andrew M. Hopkins and Roland Kothes and Sanja Lazarević and Denis Leahy and Emil Lenc and Yik Ki Ma and Cameron L. Van Eck}, doi = {10.3847/1538-4357/adad66}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {162}, shortjournal = {The Astrophys. J.}, title = {ASKAP observations of the radio shell in the composite supernova remnant g310.6-1.6}, volume = {980}, year = {2025}, }
• (2025). A comprehensive study of type i (Thermonuclear) bursts in the new transient SRGA j144459.2–604207. ApJ, 980(2), 161. (www)

  @article{ , abstract = {We report an analysis of Insight-HXMT observations of the newly discovered accreting millisecond pulsar SRGA J144459.2–604207. During the outburst, detected in 2024 February by SRG/ART-XC, the broadband persistent spectrum was well fitted by an absorbed Comptonization model. We detected 60 type I X-ray bursts in the Insight-HXMT medium energy (ME) data, and 37 were also detected with the low-energy (LE) telescope. By superimposing the Insight-HXMT/LE/ME/HE light curves of 37 bursts with similar profiles and intensities, we measured a deficit of X-rays in the 40–70 keV energy band. By analyzing the time-resolved X-ray burst spectra, we determine the mean ratio of persistent to burst flux of α = 71 ± 7. We estimate the average hydrogen mass fraction in the fuel at ignition, as \overline{X}=0.342\pm 0.033 , and constrain the burst fuel composition as X 0 ≲ 0.4. We found that 14 out of 60 X-ray bursts exhibited photospheric expansion, and thus we estimated the distance to the source as 10.03 ± 0.71 kpc. Combined with IXPE observations, the burst recurrence time increased from 1.55 to 8 hr as the local mass accretion rate decreased, which can be described as {\rm{\Delta }}{T}_{{\rm{rec}}}\sim {\dot{m}}^{-0.91\pm 0.02} .}, archive = {J_ApJ}, author = {Tao Fu and Zhaosheng Li and Yuanyue Pan and Long Ji and Yupeng Chen and Lucien Kuiper and Duncan K. Galloway and Maurizio Falanga and Renxin Xu and Xiaobo Li and Mingyu Ge and L. M. Song and Shu Zhang and Shuang-Nan Zhang}, doi = {10.3847/1538-4357/adadee}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {161}, shortjournal = {The Astrophys. J.}, title = {A comprehensive study of type i (Thermonuclear) bursts in the new transient SRGA j144459.2–604207}, volume = {980}, year = {2025}, }
• (2025). Detection of the extended γ-ray emission around TeV source 1LHAASO j0249+6022 with fermi-LAT. ApJ, 980(2), 160. (www)

  @article{ , abstract = {1LHAASO J0249+6022 is an extended very-high-energy γ -ray source discovered by the Large High-Altitude Air Shower Observatory. Based on nearly 16.1 yr of data from the Fermi Large Area Telescope, we report the probable γ -ray emission from 1LHAASO J0249+6022 in the 0.03–1 TeV energy range. The results show that its γ -ray spectrum can be well fitted by a single power law with an index of 1.54 ± 0.17, and integral photon flux is (4.28 ± 1.03) × 10 −11 photons cm −2 s −1 . We also considered theoretically whether the nonthermal emission could originate from a pulsar wind nebula (PWN) scenario. Assuming that the particles injected into the nebula have a power-law distribution, the resulting spectrum from the inverse Compton scattering is consistent with the detected GeV and TeV γ -ray fluxes. Our study shows that the PWN scenario is reasonable for 1LHAASO J0249+6022.}, archive = {J_ApJ}, author = {Yunlu Gong and Liancheng Zhou and Qi Xia and Shan Chang and Jun Fang and Li Zhang}, doi = {10.3847/1538-4357/adadfc}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {160}, shortjournal = {The Astrophys. J.}, title = {Detection of the extended γ-ray emission around TeV source 1LHAASO j0249+6022 with fermi-LAT}, volume = {980}, year = {2025}, }
• (2025). The detection rate of associated mg ii absorption lines in quasars depends on their radio emission. ApJ, 980(2), 159. (www)

  @article{ , abstract = {In active galactic nuclei, jet-driven feedback plays a significant role in influencing the properties of gas within their host galaxy and the circumgalactic medium. By combining observations from the Very Large Array Sky Survey, the Faint Images of the Radio Sky at Twenty-cm, the LOFAR Two Meter Sky Survey, and the Sloan Digital Sky Survey (SDSS), we assembled a sample of 3141 radio-loud quasars, among which 418 exhibit Mg ii -associated absorption lines in their SDSS spectra. We classify these quasars into evolutionary stages based on their radio spectral shapes. Our analysis reveals that evolved quasars exhibit a significantly higher incidence of Mg ii -associated absorption lines compared to younger sources, particularly among quasars with "nonpeaked" radio spectra, which show an incidence of Mg ii -associated absorbers approximately 1.7 times greater than that of gigahertz-peaked spectrum sources. This observation can be explained effectively by jet-driven feedback. As quasars age, their jets expand and expel substantial amounts of gas from smaller scales to larger scales, ultimately reaching the circumgalactic medium. The gas expelled from the inner regions and distributed over larger scales results in a greater coverage fraction of absorbing gas. Consequently, evolved quasars exhibit a higher incidence of Mg ii absorption lines.}, archive = {J_ApJ}, author = {Zhi-Fu Chen and Luis C. Ho}, doi = {10.3847/1538-4357/adaea2}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {159}, shortjournal = {The Astrophys. J.}, title = {The detection rate of associated mg ii absorption lines in quasars depends on their radio emission}, volume = {980}, year = {2025}, }
• (2025). X-Ray/Radio quasiperiodic pulsations associated with plasmoids in solar flare current sheets. ApJ, 980(2), 158. (www)

  @article{ , abstract = {Plasmoids (or magnetic islands) are believed to play an important role in the onset of fast magnetic reconnection and particle acceleration during solar flares and eruptions. Direct imaging of flare current sheets and the formation/ejection of multiple plasmoids in extreme-ultraviolet images, along with simultaneous X-ray and radio observations, offers significant insights into the mechanisms driving particle acceleration in solar flares. Here, we present direct imaging of the formation and ejection of multiple plasmoids in flare plasma/current sheets and the associated quasiperiodic pulsations (QPPs) observed at X-ray and radio wavelengths, using observations from the Solar Dynamics Observatory/Atmospheric Imaging Assembly, RHESSI, and the Fermi Gamma-ray Burst Monitor. These plasmoids propagate bidirectionally upward and downward along the flare current sheet beneath the erupting flux rope during two successive flares associated with confined/failed eruptions. The flux rope exhibits evidence of helical kink instability, with the formation and ejection of multiple plasmoids in the flare current sheet, as predicted in an MHD simulation of a kink-unstable flux rope. RHESSI X-ray images show double coronal sources ("looptop" and higher coronal sources) located at both ends of the flare current/plasma sheet. Moreover, we detect an additional transient faint X-ray source (6–12 keV) located between the double coronal sources, which is cospatial with multiple plasmoids in the flare current sheet. X-ray (soft and hard) and radio (decimetric) observations unveil QPPs (periods ≈ 10 s and 100 s) associated with the ejection and coalescence of plasmoids. These observations suggest that energetic electrons are accelerated during the ejection and coalescence of multiple plasmoids in the flare current sheet.}, archive = {J_ApJ}, author = {Pankaj Kumar and Judith T. Karpen and Joel T. Dahlin}, doi = {10.3847/1538-4357/ada293}, journal = {The Astrophysical Journal}, month = {2}, number = {2}, pages = {158}, shortjournal = {The Astrophys. J.}, title = {X-Ray/Radio quasiperiodic pulsations associated with plasmoids in solar flare current sheets}, volume = {980}, year = {2025}, }
• (2025). WALLABY pilot survey: Star formation enhancement and suppression in gas-rich galaxy pairs. ApJ, 980(1), 157. (www)

  @article{ , abstract = {Galaxy interactions can significantly affect the star formation in galaxies, but it remains a challenge to achieve a consensus on the star formation rate (SFR) enhancement in galaxy pairs. Here, we investigate the SFR enhancement of gas-rich galaxy pairs detected by the Widefield ASKAP L -band Legacy All-sky Blind surveY. We construct a sample of 278 paired galaxies spanning a stellar mass ( M * ) range from 10 7.6 to 10 11.2 M ⊙ . We obtain individual masses of atomic hydrogen (H i ) for these paired galaxies using a novel deblending algorithm for H i data cubes. Quantifying the interaction stages and strengths with parameters motivated by first-principles analysis, we find that, at fixed stellar and H i mass, the alteration in the SFR of galaxy pairs starts when their dark matter halos are encountered. For galaxies with a stellar mass lower than 10 9 M ⊙ , their SFRs show tentative suppression of 1.4 σ after the halo encounter, and then become enhanced when their H i disks overlap, regardless of mass ratios. In contrast, the SFRs of galaxies with M * > 10 9 M ⊙ increase monotonically toward smaller projected distances and radial velocity offsets. When a close companion is present, a pronounced SFR enhancement is found for the most H i -poor high-mass galaxies in our sample. Collecting the observational evidence, we provide a coherent picture of the evolution of galaxy pairs and discuss how the tidal effects and hydrodynamic processes shape the SFR enhancement. Our results provide a coherent picture of gas-rich galaxy interactions and impose constraints on the underlying physical processes.}, archive = {J_ApJ}, author = {Qifeng Huang and Jing Wang and Xuchen Lin and Se-Heon Oh and Xinkai Chen and B. Catinella and N. Deg and H. Dénes and B. -Q. For and B. S. Koribalski and K. Lee-Waddell and J. Rhee and A. X. Shen and Li Shao and K. Spekkens and L. Staveley-Smith and T. Westmeier and O. I. Wong and A. Bosma}, doi = {10.3847/1538-4357/ad9579}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {157}, shortjournal = {The Astrophys. J.}, title = {WALLABY pilot survey: Star formation enhancement and suppression in gas-rich galaxy pairs}, volume = {980}, year = {2025}, }
• (2025). The unique helium nova v445 puppis ejected ≫0.001 m⊙ in the year 2000 and will not become a type ia supernova. ApJ, 980(1), 156. (www)

  @article{ , abstract = {V445 Puppis (Nova Puppis 2000) is the only known example of a helium nova, where a layer of helium-rich gas accretes onto the surface of a white dwarf (WD) in a cataclysmic variable, with runaway helium burning making for the nova event. Speculatively, a helium nova can provide one path to produce a Type Ia supernova (SNIa), within the larger framework of single-degenerate models. Relatively little has been known about V445 Pup, with this work reporting the discovery of the orbital period near 1.87 days. The companion star is 2.65 ± 0.35 R ⊙ in radius as an evolved giant star stripped of its outer hydrogen envelope. The orbital period immediately before the 2000 eruption was {P}_{{\rm{pre}}} = 1.871843 ± 0.000014 days, with a steady period change of (−0.17 ± 0.06) × 10 −8 from 1896 to 1995. The period immediately after the nova eruption was P post = 1.873593 ± 0.000034 days, with a \dot{P} of (−4.7 ± 0.5) × 10 −8 . The fractional orbital period change (Δ P / P ) is +935 ± 27 ppm. This restricts the mass of the gases ejected in the nova eruption to be ≫0.001 M ⊙ , and much greater than the mass accreted to trigger the nova. So the WD is losing mass over each eruption cycle, and will not become a SNIa. Further, for V445 Pup and helium novae in general, I collect observations from 136 normal SNIa for which any giant or subgiant companion star would have been detected, yet zero companions are found. This is an independent proof that V445 Pup and helium novae are not SNIa progenitors.}, archive = {J_ApJ}, author = {Bradley E. Schaefer}, doi = {10.3847/1538-4357/ada38d}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {156}, shortjournal = {The Astrophys. J.}, title = {The unique helium nova v445 puppis ejected ≫0.001 m⊙ in the year 2000 and will not become a type ia supernova}, volume = {980}, year = {2025}, }
• (2025). Discovering large-scale structure at 2 < z < 5 in the C3VO survey. ApJ, 980(1), 155. (www)

  @article{ , abstract = {The Charting Cluster Construction with VUDS and ORELSE (C3VO) survey is an ongoing imaging and spectroscopic campaign aiming to map out the growth of structure up to z ∼ 5 and was born from the combination of the Visible Multi-Object Spectrograph Ultra Deep Survey and the Observations of Redshift Evolution in Large-Scale Environments (ORELSE) survey. As we previously accomplished with the ORELSE survey, we apply our technique known as Voronoi tessellation Monte Carlo (VMC) mapping to search for serendipitous galaxy overdensities at 2 < z < 5 in the three C3VO fields. We also apply the same technique to mock observations of simulated galaxies with properties derived from the GAlaxy Evolution and Assembly semianalytic model in order to judge the effectiveness of our search algorithm as a function of redshift, total mass, and fraction of spectroscopic redshifts. We find completeness and purity values of the order of 30%–50% for \mathrm{log}({M}_{z=0}/{M}_{\odot })\gt 14 and 2 < z < 4, with a strong dependence on mass and redshift, with values as high as ∼80% and ∼70%, respectively, in the best-case scenario for \mathrm{log}({M}_{z=0}/{M}_{\odot })\gt 14.5 . In the C3VO fields, we were able to recover many of the previously known structures in the literature as well as find hundreds of new overdensity candidates, once again demonstrating the powerful capabilities of VMC mapping when applied to wide-field optical and infrared galaxy evolution surveys at ever higher redshifts.}, archive = {J_ApJ}, author = {Denise Hung and Brian C. Lemaux and Olga Cucciati and Ben Forrest and Ekta A. Shah and Roy R. Gal and Finn Giddings and Derek Sikorski and Emmet Golden-Marx and Lori M. Lubin and Nimish Hathi and Giovanni Zamorani and Lu Shen and Sandro Bardelli and Letizia P. Cassarà and Gabriella De Lucia and Fabio Fontanot and Bianca Garilli and Lucia Guaita and Michaela Monika Hirschmann and Kyoung-Soo Lee and Andrew B. Newman and Vandana Ramakrishnan and Daniela Vergani and Lizhi Xie and Elena Zucca}, doi = {10.3847/1538-4357/ada616}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {155}, shortjournal = {The Astrophys. J.}, title = {Discovering large-scale structure at 2 < z < 5 in the C3VO survey}, volume = {980}, year = {2025}, }
• (2025). Interstellar pickup ion observations to 60 au. ApJ, 980(1), 154. (www)

  @article{ , abstract = {Prior to the Solar Wind Around Pluto (SWAP) observations from New Horizons, the only significant interstellar pickup ion (PUI) observations were taken inside 5.4 au from the Ulysses and 1 au missions. Here, we analyze SWAP data to provide the first comprehensive radial profile of interstellar PUIs in the outer heliosphere from ∼22 to 60 au. This study is the first to combine the low time resolution (one day) data inside 49.5 au with the high time resolution (half hour) data outside of that. We show that these two data sets can be reliably analyzed together in what is now a nearly continuous set of PUI observations. We derive radial gradients for all of the PUI parameters, as well as ratios to their solar wind counterparts from these combined data and extrapolate them out to a nominal termination shock distance at ∼90 au. We find that the fraction of PUIs to all ions in the solar wind continues to grow, reaching ∼18% by 60 au and extrapolated to be ∼30% at 90 au. The PUI internal pressure is ∼11% of the solar wind dynamic pressure at 60 au and expected to be ∼21% by 90 au. Such large values further highlight the importance of PUIs as the dominant driver of the physics of the outer heliosphere, as well as at the termination shock.}, archive = {J_ApJ}, author = {D. J. McComas and B. L. Shrestha and G. Livadiotis and J. R. Szalay and E. J. Zirnstein and H. A. Elliott and P. C. Brandt and A. R. Poppe and K. N. Singer and A. Stern and A. Verbiscer and the New Horizons Heliophysics Team}, doi = {10.3847/1538-4357/ada6b1}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {154}, shortjournal = {The Astrophys. J.}, title = {Interstellar pickup ion observations to 60 au}, volume = {980}, year = {2025}, }
• (2025). Multiwavelength variability analysis of the blazar PKS 0727-11: An ~ 168 day quasiperiodic oscillation in the γ-ray. ApJ, 980(1), 153. (www)

  @article{ , abstract = {We performed variability analysis of the multiwavelength light curves (LCs) for the flat-spectrum radio quasar PKS 0727-11. Using the generalized Lomb–Scargle periodogram, we identified a possible quasiperiodic oscillation (QPO) of ~168.6 days (persisted for six cycles, with a significance of 3.8 σ ) in the γ -ray LC during the flare period (MJD 54687–55738). It is the first time that periodic variations have been detected in this source, and further supported by other methods: weighted wavelet z -transform, phase dispersion minimization, REDFIT, autoregressive integrated moving average model, and structure function analysis. Cross-correlation analysis shows that there is a strong correlation between multiband light variations, indicating that γ -ray and radio flares may originate from the same disturbance, and the distance between the emission regions of γ -ray and radio flares is calculated based on the time lag. We demonstrate that QPO arising from the non-ballistic helical jet motion driven by the orbital motion in a supermassive binary black hole is a plausible physical explanation. In this scenario, the estimated mass of the primary black hole is M ∼ 3.66 × 10 8 –5.79 × 10 9 M ⊙ .}, archive = {J_ApJ}, author = {Yuncai Shen and Tingfeng Yi and Vinit Dhiman and Lisheng Mao and Liang Dong}, doi = {10.3847/1538-4357/ada775}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {153}, shortjournal = {The Astrophys. J.}, title = {Multiwavelength variability analysis of the blazar PKS 0727-11: An ~ 168 day quasiperiodic oscillation in the γ-ray}, volume = {980}, year = {2025}, }
• (2025). Blowin’ in the nonisothermal wind: Core-powered mass loss with hydrodynamic radiative transfer. ApJ, 980(1), 152. (www)

  @article{ , abstract = {The mass loss rates of planets undergoing core-powered escape are usually modeled using an isothermal Parker-type wind at the equilibrium temperature, T eq . However, the upper atmospheres of sub-Neptunes may not be isothermal if there are significant differences between the opacity to incident visible and outgoing infrared radiation. We model bolometrically driven escape using AIOLOS, a hydrodynamic radiative-transfer code that incorporates double-gray opacities, to investigate the process's dependence on the visible-to-infrared opacity ratio, γ . For a value of γ ≈ 1, we find that the resulting mass loss rates are well approximated by a Parker-type wind with an isothermal temperature T = T eq /2 1/4 . However, we show that over a range of physically plausible values of γ , the mass loss rates can vary by orders of magnitude, ranging from 10 −5 × the isothermal rate for low γ to 10 5 × the isothermal rate for high γ . The differences in mass loss rates are largest for small planet radii, while for large planet radii, mass loss rates become nearly independent of γ and approach the isothermal approximation. We incorporate these opacity-dependent mass loss rates into a self-consistent planetary mass and energy evolution model and show that lower/higher γ values lead to more/less hydrogen being retained after core-powered mass loss. In some cases, the choice of opacities determines whether or not a planet can retain a significant primordial hydrogen atmosphere. The dependence of escape rate on the opacity ratio may allow atmospheric escape observations to directly constrain a planet's opacities and therefore its atmospheric composition.}, archive = {J_ApJ}, author = {William Misener and Matthäus Schulik and Hilke E. Schlichting and James E. Owen}, doi = {10.3847/1538-4357/ada777}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {152}, shortjournal = {The Astrophys. J.}, title = {Blowin’ in the nonisothermal wind: Core-powered mass loss with hydrodynamic radiative transfer}, volume = {980}, year = {2025}, }
• (2025). Magnetorotational instability in collisional weakly ionized plasma with distinct species velocities. ApJ, 980(1), 151. (www)

  @article{ , abstract = {In a differential rotating system, we use the incompressible multifluid model to investigate the dynamics of a weakly ionized plasma placed in a vertical background magnetic field with radial shearing. The equilibrium current is taken into account. The differences in velocities between charged species and neutrals are supposed to be related to the collisions. The analytical expression of the general local dispersion relation is derived and the effect of the shearing magnetic field is demonstrated in three different limiting cases. Momentum transfer to neutrals is neglected in the first case, and the instability criteria are provided with the involvement of magnetic field shearing. In the magnetohydrodynamic (MHD) case, the previous results are reproduced when setting the equilibrium current density to zero, and the magnetic field structure is depicted to restrain/reinforce the instability in the Keplerian system with decaying/increasing shearing. In the last case, the finite collisions with weak ionization and ion Hall effects generate another unstable vertical mode compared with the MHD case and also alleviate the unstable waves propagated between the horizontal and vertical directions.}, archive = {J_ApJ}, author = {Chenghao Zhang and Haijun Ren}, doi = {10.3847/1538-4357/ada89d}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {151}, shortjournal = {The Astrophys. J.}, title = {Magnetorotational instability in collisional weakly ionized plasma with distinct species velocities}, volume = {980}, year = {2025}, }
• (2025). Semianalytical Fokker–Planck models for nuclear star clusters. ApJ, 980(1), 150. (www)

  @article{ , abstract = {We study the dynamics of nuclear star clusters, the dense stellar environments surrounding massive black holes in the centers of galaxies. We consider angular momentum diffusion due to two-body scatterings among stellar objects and energy advection due to gravitational-wave emission upon interaction with the central massive black hole. Such dynamics are described by a 2D Fokker–Planck (FP) equation in energy–angular momentum space. Focusing on the transition between the diffusion-dominated region and the advection-dominated one, we utilize self-similarity to obtain a full solution for the steady-state FP equation. This solution provides the density and flux of the stellar objects in nuclear star clusters. This improves the rate estimates for extreme-mass ratio inspirals, and has interesting implications for a new class of galactic center transients called quasiperiodic eruptions.}, archive = {J_ApJ}, author = {Karamveer Kaur and Barak Rom and Re’em Sari}, doi = {10.3847/1538-4357/ada8a8}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {150}, shortjournal = {The Astrophys. J.}, title = {Semianalytical Fokker–Planck models for nuclear star clusters}, volume = {980}, year = {2025}, }
• (2025). Stability and convergence of nuclear detonations in white dwarf collisions. ApJ, 980(1), 149. (www)

  @article{ , abstract = {We investigate the numerical stability of thermonuclear detonations in 1D accelerated reactive shocks and 2D binary collisions of equal-mass magnetized and unmagnetized white dwarf stars. To achieve high resolution at initiation sites, we devised geometric gridding and mesh velocity strategies specially adapted to the unique requirements of head-on collisional geometries, scenarios in which one expects maximum production of iron-group products. We study the effects of grid resolution and the limiting of temperature, energy generation, and reactants for different stellar masses, separations, magnetic fields, initial compositions, detonation mechanisms, and limiter parameters across a range of cell sizes from 1 to 100 km. Our results set bounds on the parameter space of limiter amplitudes for which both temperature- and energy-limiting procedures yield consistent and monotonically convergent solutions. Within these bounds, we find that grid resolutions of 5 km or better are necessary for uncertainties in total released energy and iron-group products to drop below 10%. Intermediate-mass products (e.g., calcium) exhibit similar convergence trends but with somewhat greater uncertainty. These conclusions apply equally to pure C/O white dwarfs, multispecies compositions (including helium shells), magnetized and unmagnetized cores, and either single or multiple detonation scenarios.}, archive = {J_ApJ}, author = {Peter Anninos and David Cruz-Lopez and Brighten Jiang and Emanuel Gordis}, doi = {10.3847/1538-4357/ada9e3}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {149}, shortjournal = {The Astrophys. J.}, title = {Stability and convergence of nuclear detonations in white dwarf collisions}, volume = {980}, year = {2025}, }
• (2025). MINDS. JWST-MIRI observations of a spatially resolved atomic jet and polychromatic molecular wind toward SY cha. ApJ, 980(1), 148. (www)

  @article{ , abstract = {The removal of angular momentum from protostellar systems drives accretion onto the central star and may drive the dispersal of the protoplanetary disk. Winds and jets can contribute to removing angular momentum from the disk, though the dominant process remains unclear. To date, observational studies of resolved disk winds have mostly targeted highly inclined disks. We report the detection of extended H 2 and [Ne ii ] emission toward the young stellar object SY Cha with the JWST Mid-InfraRed Instrument Medium-Resolution Spectrometer (MIRI-MRS). This is one of the first polychromatic detections of extended H 2 toward a moderately inclined, i = 51 \mathop{.}\limits^{\unicode{x000B0}} 1, Class II source. We measure the semiopening angle of the H 2 emission and build a rotation diagram to determine the H 2 excitation temperature and abundance. We find a wide semiopening angle, high temperature, and low column density for the H 2 emission, all of which are characteristic of a disk wind. We derive a molecular wind mass loss rate of 3 ± 2 × 10 −9 M ⊙ yr −1 , which is high compared to the previously derived stellar accretion rate of 6.6 × 10 −10 M ⊙ yr −1 . This suggests either that the stellar accretion and the disk wind are driven by different mechanisms or that accretion onto the star is highly variable. These observations demonstrate MIRI-MRS's utility in expanding studies of resolved disk winds beyond edge-on sources.}, archive = {J_ApJ}, author = {Kamber R. Schwarz and Matthias Samland and Göran Olofsson and Thomas Henning and Andrew Sellek and Manuel Güdel and Benoît Tabone and Inga Kamp and Pierre-Olivier Lagage and Ewine F. van Dishoeck and Alessio Caratti o Garatti and Adrian M. Glauser and Tom P. Ray and Aditya M. Arabhavi and Valentin Christiaens and R. Franceschi and Danny Gasman and Sierra L. Grant and Jayatee Kanwar and Till Kaeufer and Nicolas T. Kurtovic and Giulia Perotti and Milou Temmink and Marissa Vlasblom}, doi = {10.3847/1538-4357/adaa79}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {148}, shortjournal = {The Astrophys. J.}, title = {MINDS. JWST-MIRI observations of a spatially resolved atomic jet and polychromatic molecular wind toward SY cha}, volume = {980}, year = {2025}, }
• (2025). Kinetic and photochemical disequilibrium in the potentially carbon-rich atmosphere of the warm jupiter WASP-69 b. ApJ, 980(1), 147. (www)

  @article{ , abstract = {High-resolution transmission spectroscopy of the warm gas giant WASP-69 b has revealed the presence of H 2 O, CO, CH 4 , NH 3 , and C 2 H 2 in its atmosphere. This study investigates the impact of vertical diffusion and photochemistry on its atmospheric composition, with a focus on the detected species plus HCN and CO 2 , to constrain the atmospheric C/O ratio. We utilize nonequilibrium gas-phase simulations to conduct a parameter study for vertical diffusion strength, local gas temperature, and C/O ratio. Our results indicate that a carbon-rich atmosphere enhances CH 4 and C 2 H 2 concentrations, while NH 3 undergoes chemical conversion into HCN in carbon-rich, high-temperature environments. Consequently, HCN is abundantly produced in such atmospheres, though its strong spectral features remain undetected in WASP-69 b. Photochemical production of HCN and C 2 H 2 is highly sensitive to vertical diffusion strength, with weaker diffusion resulting in higher concentrations. Cross-correlation of synthetic spectra with observed data shows that models with C/O = 2 best match observations, but models with C/O = 0.55 and 0.9 lead to statistically equivalent fits, leaving the C/O ratio unconstrained. We highlight the importance of accurately modeling NH 3 quenching at pressures greater than 100 bars. Models for WASP-69 b capped at 100 bars bias cross-correlation fits toward carbon-rich values. We suggest that if the atmosphere of WASP-69 b is indeed carbon-rich with a solar metallicity, future observations should reveal the presence of HCN.}, archive = {J_ApJ}, author = {Nidhi Bangera and Christiane Helling and Gloria Guilluy and Patricio Cubillos and Luca Fossati and Paolo Giacobbe and Paul Rimmer and Daniel Kitzmann}, doi = {10.3847/1538-4357/adaa7d}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {147}, shortjournal = {The Astrophys. J.}, title = {Kinetic and photochemical disequilibrium in the potentially carbon-rich atmosphere of the warm jupiter WASP-69 b}, volume = {980}, year = {2025}, }
• (2025). The impact of bar-induced noncircular motions on the measurement of galactic rotation curves. ApJ, 980(1), 146. (www)

  @article{ , abstract = {We study the impact of bar-induced noncircular motions on the derivation of galactic rotation curves (RCs) using hydrodynamic simulations and observational data from the PHANGS-ALMA survey. We confirm that noncircular motions induced by a bar can significantly bias RCs derived from the conventional tilted-ring method, consistent with previous findings. The shape of the derived RC depends on the difference in position angle (Δ ϕ ) between the major axes of the bar and the disk in the face-on plane. For \left|{\rm{\Delta }}\phi \right|\lesssim 40^\circ , noncircular motions produce a bar-induced "dip" feature (rise–drop–rise pattern) in the derived RC, which shows higher velocities near the nuclear ring and lower velocities in the bar region compared to the true RC (RC true ). We demonstrate convincingly that such dip features are very common in the PHANGS-ALMA sample of barred galaxies. Hydrodynamical simulations reveal that the "dip" feature is caused by the perpendicular orientation of the gas flows in the nuclear ring and the bar; at low \left|{\rm{\Delta }}\phi \right| streamlines in the nuclear ring tend to enhance V los , while those in the bar tend to suppress V los . We use a simple "misaligned ellipses" model to qualitatively explain the general trend of RCs from the tilted-ring method (RC tilted ) and the discrepancy between RC tilted and RC true . Furthermore, we propose a straightforward method to implement a first-order correction to the RC derived from the tilted-ring method. Our study is the first to systematically discuss the bar-induced "dip" feature in the RCs of barred galaxies by combining both simulations and observations.}, archive = {J_ApJ}, author = {Jie Liu and Zhi Li and Juntai Shen}, doi = {10.3847/1538-4357/adabe0}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {146}, shortjournal = {The Astrophys. J.}, title = {The impact of bar-induced noncircular motions on the measurement of galactic rotation curves}, volume = {980}, year = {2025}, }
• (2025). What drives the h i content of central Galaxies—A comparison between hydrodynamic simulations and observations using random forest. ApJ, 980(1), 145. (www)

  @article{ , abstract = {We investigate the driving mechanisms for the H i gas content in star-forming central galaxies at low redshift, by examining the H i -to-stellar mass ratio ( M H i / M * ) in both the state-of-the-art hydrodynamic simulations, IllustrisTNG (TNG) and EAGLE, and the xGASS sample. We quantify the correlations of M H i / M * with a variety of galaxy properties using the Random Forest regression technique, and we make comparisons between the two simulations, as well as between the simulations and xGASS. Gas-phase metallicity is found to be most important in both simulations, but is ranked mildly for xGASS, suggesting that metals and gas driven by feedback effects in real galaxies is not as tightly coupled as in the simulations. Beyond that, the accretion rate of supermassive black holes is the most important feature in TNG, while specific star formation rate is the top ranked in EAGLE. This result can be understood from the fact that the H i gas is regulated mainly by thermal-mode AGN feedback in TNG and by stellar feedback in EAGLE. Although neither simulation can fully reproduce the feature importance obtained for real galaxies in the xGASS, EAGLE performs better than TNG in the sense that the observationally top-ranked property, u − r , is also highly ranked in EAGLE. This result implies that stellar feedback plays a more dominant role than AGN feedback in driving the H i gas content of low-redshift galaxies.}, archive = {J_ApJ}, author = {Xiao Li and Cheng Li and H. J. Mo}, doi = {10.3847/1538-4357/adace2}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {145}, shortjournal = {The Astrophys. J.}, title = {What drives the h i content of central Galaxies—A comparison between hydrodynamic simulations and observations using random forest}, volume = {980}, year = {2025}, }
• (2025). Continuous gravitational waves from thermal mountains on accreting neutron stars: Effect of the nuclear pasta phase. ApJ, 980(1), 144. (www)

  @article{ , abstract = {As density increases, the shape of nuclei transitions to nonspherical "nuclear pasta" structures. The physical properties of the nuclear pasta, such as thermal conductivity and elasticity, have implications for detecting continuous gravitational waves from a rapidly rotating neutron star. In this work, we investigate the effect of the nuclear pasta on the quadruple moment, and find out that, compared with previous work, the quadrupole moment contributing to continuous gravitational-wave radiation can be up to 2 orders of magnitude larger. We also discuss the relationship between the quadruple moment and the maximum shear strain. Considering the properties of nuclear pasta, we study the detectability of known accreting neutron stars and compare predicted results to the detectable amplitude limits. These sources are well above the sensitivity curves for Cosmic Explorer and Einstein Telescope detectors. Our work advances the understanding of the properties of nuclear pasta and a possible mechanism for continuous gravitational waves.}, archive = {J_ApJ}, author = {Hong-Bo Li and Lijing Shao and Cheng-Jun Xia and Ren-Xin Xu}, doi = {10.3847/1538-4357/adadf2}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {144}, shortjournal = {The Astrophys. J.}, title = {Continuous gravitational waves from thermal mountains on accreting neutron stars: Effect of the nuclear pasta phase}, volume = {980}, year = {2025}, }
• (2025). Thermal spectra of warped and broken accretion disks. ApJ, 980(1), 143. (www)

  @article{ , abstract = {Black holes may accrete gas with angular momentum vectors misaligned with the black hole spin axis. The resulting accretion disks are subject to Lense–Thirring precession, and hence torque. Analytical calculations and simulations show that Lense–Thirring precession will warp, and, for large misalignments, fracture the disk. In GRMHD simulations, the warping or breaking occurs at ≲10 r s , where r s is the Schwarzschild radius. Considering that accretion disk spectra in the soft state of stellar-mass black holes are generally well modeled as multicolor blackbodies, the question arises as to how consistent warped and broken disks are with observations. Here, we analytically calculate thermal spectra of warped and broken disks with a warp or break radius at 10 r s for various disk inclinations. Due to self-irradiation and the projected area of the inclined disk regions, the spectra of inclined disks significantly deviate from multicolor blackbodies and do not follow the multicolor blackbody relation νL ν ∝ ν γ = ν 4/3 at low frequencies ν . The power-law indices at low frequencies of the inclined disks vary with viewing angle; when viewed face-on, they vary between γ ≈ 0.91 and 1.26 for the warped disks and γ ≈ 1.37–1.54 for the broken disks depending on the inclination angle. The differences decrease when moving the location of the disk warp and break to larger radii; for inclined disks to emit as multicolor blackbodies, they must warp or break at radii ≥50 r s . Our results imply that accretion disks around black holes in the soft state warp or break at larger radii than suggested in GRHMD simulations.}, archive = {J_ApJ}, author = {J. Speicher and O. Blaes}, doi = {10.3847/1538-4357/adadf4}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {143}, shortjournal = {The Astrophys. J.}, title = {Thermal spectra of warped and broken accretion disks}, volume = {980}, year = {2025}, }
• (2025). A multiwavelength light-curve analysis of the classical nova KT eri: Optical contribution from a large irradiated accretion disk. ApJ, 980(1), 142. (www)

  @article{ , abstract = {KT Eri is a classical nova that went into outburst in 2009. Recent photometric analysis in quiescence indicates a relatively longer orbital period of 2.6 days, so that KT Eri could host a very bright accretion disk during the outburst like in the recurrent nova U Sco, the orbital period of which is 1.23 days. We reproduced the optical V light curve as well as the supersoft X-ray light curve of KT Eri in outburst, assuming a large irradiated disk during a nova wind phase of the outburst while a normal size disk after the nova winds stop. This result is consistent with the temporal variation of wide-band V brightness that varies almost with the intermediate-band Strömgren y brightness, because the V flux is dominated by continuum radiation, the origin of which is a photospheric emission from the very bright disk. We determined the white dwarf mass to be M WD = 1.3 ± 0.02 M ⊙ , the hydrogen-burning turnoff epoch to be ∼240 days after the outburst, the distance modulus in the V band to be ( m − M ) V = 13.4 ± 0.2, and the distance to KT Eri to be d = 4.2 ± 0.4 kpc for the reddening of E ( B − V ) = 0.08. The peak absolute V brightness is about {M}_{V,{\rm{\max }}}=-8.0 and the corresponding recurrence time is ∼3000 yr from its ignition mass together with the mean mass-accretion rate of {\dot{M}}_{{\rm{acc}}}\sim 1\times 1{0}^{-9}\,{M}_{\odot } yr −1 in quiescence. Thus, we suggest that KT Eri is not a recurrent nova.}, archive = {J_ApJ}, author = {Izumi Hachisu and Mariko Kato and Frederick M. Walter}, doi = {10.3847/1538-4357/adae08}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {142}, shortjournal = {The Astrophys. J.}, title = {A multiwavelength light-curve analysis of the classical nova KT eri: Optical contribution from a large irradiated accretion disk}, volume = {980}, year = {2025}, }
• (2025). Early detection of multiwavelength blazar variability. ApJ, 980(1), 141. (www)

  @article{ , abstract = {Blazars are a subclass of active galactic nuclei with relativistic jets pointing toward the observer. They are notable for their flux variability at all observed wavelengths and timescales. Together with simultaneous measurements at lower energies, the very-high-energy (VHE) emission observed during blazar flares may be used to probe the population of accelerated particles. However, optimally triggering observations of blazar high states can be challenging. Notable examples include identifying a flaring episode in real time and predicting VHE flaring activity based on lower-energy observables. For this purpose, we have developed a novel deep learning analysis framework, based on data-driven anomaly detection techniques. It is capable of detecting various types of anomalies in real-world, multiwavelength light curves, ranging from clear high states to subtle correlations across bands. Based on unsupervised anomaly detection and clustering methods, we differentiate source variability from noisy background activity, without the need for a labeled training data set of flaring states. The framework incorporates measurement uncertainties and is robust given data quality challenges, such as varying cadences and observational gaps. We evaluate our approach using both historical data and simulations of blazar light curves in two energy bands, corresponding to sources observable with the Fermi Large Area Telescope and the upcoming Cherenkov Telescope Array Observatory. In a statistical analysis, we show that our framework can reliably detect known historical flares.}, archive = {J_ApJ}, author = {Hermann Stolte and Jonas Sinapius and Iftach Sadeh and Elisa Pueschel and Matthias Weidlich and David Berge}, doi = {10.3847/1538-4357/ad960c}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {141}, shortjournal = {The Astrophys. J.}, title = {Early detection of multiwavelength blazar variability}, volume = {980}, year = {2025}, }
• (2025). Maximum-likelihood regression with systematic errors for astronomy and the physical sciences. II. hypothesis testing of nested model components for poisson data. ApJ, 980(1), 140. (www)

  @article{ , abstract = {A novel model of systematic errors for the regression of Poisson data is applied to hypothesis testing of nested model components with the introduction of a generalization of the Δ C statistic that applies in the presence of systematic errors. This paper shows that the null-hypothesis parent distribution of this Δ C sys statistic can be obtained either through a simple numerical procedure, or in a closed form by making certain simplifying assumptions. It is found that the effects of systematic errors on the test statistic can be significant, and therefore the inclusion of sources of systematic errors is crucial for the assessment of the significance of the nested model component in practical applications. The methods proposed in this paper provide a simple and accurate means of including systematic errors for hypothesis testing of nested model components in a variety of applications.}, archive = {J_ApJ}, author = {Massimiliano Bonamente and Dale Zimmerman and Yang Chen}, doi = {10.3847/1538-4357/ad9b1f}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {140}, shortjournal = {The Astrophys. J.}, title = {Maximum-likelihood regression with systematic errors for astronomy and the physical sciences. II. hypothesis testing of nested model components for poisson data}, volume = {980}, year = {2025}, }
• (2025). Maximum-likelihood regression with systematic errors for astronomy and the physical sciences. i. methodology and goodness-of-fit statistic of poisson data. ApJ, 980(1), 139. (www)

  @article{ , abstract = {This paper presents a new statistical method that enables the use of systematic errors in the maximum-likelihood regression of integer-count Poisson data to a parametric model. The method is primarily aimed at the characterization of the goodness-of-fit statistic in the presence of the over-dispersion that is induced by sources of systematic error, and is based on a quasi-maximum-likelihood method that retains the Poisson distribution of the data. We show that the Poisson deviance, which is the usual goodness-of-fit statistic and that is commonly referred to in astronomy as the Cash statistics, can be easily generalized in the presence of systematic errors, under rather general conditions. The method and the associated statistics are first developed theoretically, and then they are tested with the aid of numerical simulations and further illustrated with real-life data from astronomical observations. The statistical methods presented in this paper are intended as a simple general-purpose framework to include additional sources of uncertainty for the analysis of integer-count data in a variety of practical data analysis situations.}, archive = {J_ApJ}, author = {Massimiliano Bonamente and Yang Chen and Dale Zimmerman}, doi = {10.3847/1538-4357/ad9b1e}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {139}, shortjournal = {The Astrophys. J.}, title = {Maximum-likelihood regression with systematic errors for astronomy and the physical sciences. i. methodology and goodness-of-fit statistic of poisson data}, volume = {980}, year = {2025}, }
• (2025). JWST, ALMA, and keck spectroscopic constraints on the UV luminosity functions at z ∼ 7–14: Clumpiness and compactness of the brightest galaxies in the early universe. ApJ, 980(1), 138. (www)

  @article{ , abstract = {We present the number densities and physical properties of the bright galaxies spectroscopically confirmed at z ∼ 7–14. Our sample is composed of 60 galaxies at z spec ∼ 7–14, including recently confirmed galaxies at z spec = 12.34–14.18 with JWST, as well as new confirmations at z spec = 6.583–7.643 with −24 < M UV < −21 mag using ALMA and Keck. Our JWST/NIRSpec observations have also revealed that very bright galaxy candidates at z ∼ 10–13 identified from ground-based telescope images before JWST are passive galaxies at z ∼ 3–4, emphasizing the necessity of strict screening and spectroscopy in the selection of the brightest galaxies at z > 10. The UV luminosity functions derived from these spectroscopic results are consistent with a double power-law function, showing tensions with theoretical models at the bright end. To understand the origin of the overabundance of bright galaxies, we investigate their morphologies using JWST/NIRCam high-resolution images obtained in various surveys, including PRIMER and COSMOS-Web. We find that ∼70% of the bright galaxies at z ∼ 7 exhibit clumpy morphologies with multiple subcomponents, suggesting merger-induced starburst activity, which is consistent with SED fitting results showing bursty star formation histories. At z ≳ 10, bright galaxies are classified into two types of galaxies: extended ones with weak high-ionization emission lines, and compact ones with strong high-ionization lines including N iv] λ 1486, indicating that at least two different processes (e.g., merger-induced starburst and compact star formation/AGN) are shaping the physical properties of the brightest galaxies at z ≳ 10 and are responsible for their overabundance.}, archive = {J_ApJ}, author = {Yuichi Harikane and Akio K. Inoue and Richard S. Ellis and Masami Ouchi and Yurina Nakazato and Naoki Yoshida and Yoshiaki Ono and Fengwu Sun and Riku A. Sato and Giovanni Ferrami and Seiji Fujimoto and Nobunari Kashikawa and Derek J. McLeod and Pablo G. Pérez-González and Marcin Sawicki and Yuma Sugahara and Yi Xu and Satoshi Yamanaka and Adam C. Carnall and Fergus Cullen and James S. Dunlop and Eiichi Egami and Norman Grogin and Yuki Isobe and Anton M. Koekemoer and Nicolas Laporte and Chien-Hsiu Lee and Dan Magee and Hiroshi Matsuo and Yoshiki Matsuoka and Ken Mawatari and Kimihiko Nakajima and Minami Nakane and Yoichi Tamura and Hiroya Umeda and Hiroto Yanagisawa}, doi = {10.3847/1538-4357/ad9b2c}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {138}, shortjournal = {The Astrophys. J.}, title = {JWST, ALMA, and keck spectroscopic constraints on the UV luminosity functions at z ∼ 7–14: Clumpiness and compactness of the brightest galaxies in the early universe}, volume = {980}, year = {2025}, }
• (2025). Propagation of interplanetary shocks in the inner heliosphere. ApJ, 980(1), 137. (www)

  @article{ , abstract = {Interplanetary (IP) shocks are one of the crucial dynamic phenomena in the heliosphere. They can accelerate particles to high energies, generate plasma waves, and trigger geomagnetic storms in Earth's magnetosphere, significantly impacting technological infrastructure. In this study, two IP shock events are selected to study the temporal variations of the shock parameters using magnetometer and ion plasma measurements from STEREO-A and B, the Wind, Cluster fleet, and the Advanced Composition Explorer spacecraft. The shock normal vectors are determined using minimum variance analysis and magnetic coplanarity methods. During the 2007 May 7 event, the shock parameters and the shock normal direction remain consistent across each spacecraft crossing of the shock. The shock surface appears to be tilted by almost the same degree as the Parker spiral, and the driver could be a corotating interaction region (CIR). During the 2007 April 23 event, the shock parameters do not change significantly except for the shock angle θ Bn ; however, the shape of the IP shock appears to be twisted in the direction perpendicular to the Sun–Earth line as well. The driver of this rippled shock is a stream interaction region/CIR as well.}, archive = {J_ApJ}, author = {Munkhjargal Lkhagvadorj and Gábor Facskó and Andrea Opitz and Péter Kovács and David G. Sibeck}, doi = {10.3847/1538-4357/ad9d12}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {137}, shortjournal = {The Astrophys. J.}, title = {Propagation of interplanetary shocks in the inner heliosphere}, volume = {980}, year = {2025}, }
• (2025). Multimessenger probes of supermassive black hole spin evolution. ApJ, 980(1), 136. (www)

  @article{ , abstract = {Using the semianalytic model Serotina , we investigate the cosmic spin evolution of supermassive black holes (SMBHs) incorporating recent results from general-relativistic magnetohydrodynamics simulations of spin-down from relativistic jets. We compare several variations of our model with compiled black hole (BH) spin measurements derived from X-ray reflection spectroscopy, correcting for a bias arising from the spin-dependent radiative efficiency of accretion flows. We show that the observed spin distribution is in agreement with a model that includes jet-driven spin-down, a key mechanism that acts to modulate spins across cosmic time at both high and very low specific accretion rates. The data also clearly prefer models with coherent accretion over models in which accretion disks rapidly switch from prograde to retrograde. We further predict spin distributions accessible via spatially resolved event horizons by the next-generation Event Horizon Telescope and Black Hole Explorer, as well as gravitational waves by the Laser Interferometer Space Antenna (LISA), each of which offers unique and distinct windows into the population of spinning BHs. Jet-driven spin-down is most strongly imprinted on the abundance of very highly spinning objects in our model. In addition, we show that the spin distribution sampled by LISA events may contain a signature of the natal spin distribution of heavy seeds, but not of light seeds, offering additional discrimination between these seeding pathways. Spin distributions from these future observed samples can be used to constrain the detailed physical properties of the accretion flow on horizon scales around SMBHs.}, archive = {J_ApJ}, author = {Angelo Ricarte and Priyamvada Natarajan and Ramesh Narayan and Daniel C. M. Palumbo}, doi = {10.3847/1538-4357/ad9ea9}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {136}, shortjournal = {The Astrophys. J.}, title = {Multimessenger probes of supermassive black hole spin evolution}, volume = {980}, year = {2025}, }
• (2025). Hooks, lines, and sinkers: How active galactic nucleus feedback and cosmic-ray transport shape the far-infrared–Radio correlation of galaxies. ApJ, 980(1), 135. (www)

  @article{ , abstract = {The far-infrared–radio correlation (FRC) is one of the most promising empirical constraints on the role of cosmic rays (CRs) and magnetic fields in galaxy formation and evolution. While many theories have been proposed in order to explain the emergence and maintenance of the FRC across a gamut of galaxy properties and redshift, the nonlinear physics at play remain unexplored in full complexity and within a cosmological context. We present the first reproduction of the z ∼ 0 FRC using detailed synthetic observations of state-of-the-art cosmological zoom-in simulations from the Feedback in Realistic Environments (FIRE-3) suite with explicitly evolved CR proton and electron (CRe) spectra, for three models for CR transport and multichannel active galactic nucleus (AGN) feedback. In doing so, we generally verify the predictions of "calorimeter" theories at high FIR luminosities ( L 60 μ m ≳ 10 9.5 L ⊙ ) and at low FIR luminosities ( L 60 μ m ≲ 10 9.5 L ⊙ ), the so-called "conspiracy" of increasing UV radiation escape in tandem with increasing CRe escape, and find that the global FRC is insensitive to orders-of-magnitude locally variable CR transport coefficients. Importantly, the indirect effect of AGN feedback on emergent observables highlights novel interpretations of outliers in the FRC. In particular, we find that in many cases "radio-excess" objects can be better understood as "IR-dim" objects with longer-lived radio contributions at low z from Type Ia supernovae and intermittent black hole accretion in quenching galaxies, though this is sensitive to the interplay of CR transport and AGN feedback physics. This creates characteristic evolutionary tracks leading to the z = 0 FRC, which shape the subsequent late-time behavior of each model.}, archive = {J_ApJ}, author = {Sam B. Ponnada and Rachel K. Cochrane and Philip F. Hopkins and Iryna S. Butsky and Sarah Wellons and N. Nicole Sanchez and Cameron Hummels and Yue Samuel Lu and Dušan Kereš and Christopher C. Hayward}, doi = {10.3847/1538-4357/ada280}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {135}, shortjournal = {The Astrophys. J.}, title = {Hooks, lines, and sinkers: How active galactic nucleus feedback and cosmic-ray transport shape the far-infrared–Radio correlation of galaxies}, volume = {980}, year = {2025}, }
• (2025). Understanding the broad-line region of active galactic nuclei with photoionization. i. the moderate-accretion regime. ApJ, 980(1), 134. (www)

  @article{ , abstract = {Over three decades of reverberation mapping (RM) studies on local broad-line active galactic nuclei (AGNs) have measured reliable black hole (BH) masses for >100 AGNs. These RM measurements reveal a significant correlation between the Balmer broad-line region (BLR) size and AGN optical luminosity (the R – L relation). Recent RM studies for AGN samples with more diverse BH parameters (e.g., mass and Eddington ratio) reveal a substantial intrinsic dispersion around the average R – L relation, suggesting that variations in the broadband spectrum, driven by accretion parameters and other factors such as the cloud distribution and inclination, significantly influence the measured R – L relation. Here we perform a detailed photoionization investigation of expected broad-line properties as functions of accretion parameters using AGN continuum models from qsosed . We compare theoretical predictions with observations of a sample of 67 z ≲ 0.5 reverberation-mapped AGNs with rest-frame optical and UV spectra in the moderate-accretion regime (Eddington ratio λ Edd ≡ L / L Edd < 0.5). The UV/optical line strengths and their dependences on accretion parameters are reasonably well reproduced by the locally optimally emitting cloud photoionization models. We provide quantitative recipes using optical/UV line flux ratios to infer the unobservable ionizing continuum. Additionally, photoionization models with universal values of ionization parameter ( \mathrm{log}\,{U}_{{\rm{H}}}=-2 ) and hydrogen density ( \mathrm{log}\,n({\rm{H}})=12 ) can qualitatively reproduce the observed global R – L relation for the current RM AGN sample. However, such models fail to reproduce the observed decrease in BLR size with increasing L / L Edd at fixed optical luminosity, implying that gas density or BLR structure may systematically change with accretion rate.}, archive = {J_ApJ}, author = {Qiaoya Wu and Yue Shen and Hengxiao Guo and Scott F. Anderson and W. N. Brandt and Catherine J. Grier and Patrick B. Hall and Luis C. Ho and Yasaman Homayouni and Keith Horne and Jennifer I-Hsiu Li and Donald P. Schneider}, doi = {10.3847/1538-4357/ada386}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {134}, shortjournal = {The Astrophys. J.}, title = {Understanding the broad-line region of active galactic nuclei with photoionization. i. the moderate-accretion regime}, volume = {980}, year = {2025}, }
• (2025). Uncovering the hidden physical structures and protostellar activities in the low-metallicity s284-RE region: Results from ALMA and JWST. ApJ, 980(1), 133. (www)

  @article{ , abstract = {We present an observational study of the S284-RE region, a low-metallicity area associated with the extended S284 H ii region. A thermally supercritical filament (mass ∼2402 M ⊙ and length ∼8.5 pc) is investigated using the Herschel column density map. The Spitzer ratio 4.5 μ m/3.6 μ m map traces the H 2 outflows in this filament, where previously reported young stellar objects (YSOs) are spatially distributed. Analysis of the YSO distribution has revealed three active star-forming clusters (YCl1, YCl2, and YCl3) within the filament. YCl3 seems to be the most evolved and YCl2 the youngest, while YCl1 displays signs of nonthermal fragmentation. The JWST (F470N+F444W)/F356W ratio map reveals at least seven bipolar H 2 outflows, with four (olc1–olc4) in YCl1 and three (ol1–ol3) in YCl2. The driving sources of these outflows are identified based on outflow geometry, Atacama Large Millimeter/submillimeter Array (ALMA) continuum peaks, and YSO positions. Two ALMA continuum sources—#2 and #3—from the M – R eff plot are recognized as potential massive star formation candidates. ALMA continuum source #2 hosts at least three outflow-driving sources, whereas ALMA continuum source #3 contains two. The bipolar outflow olc1, driven by an embedded object within continuum source #2, is likely a massive protostar, as indicated by the Br- α and PAH emissions depicted in the JWST (F405N+F444W)/F356W ratio map. The presence of H 2 knots in the outflows olc1 and ol1 suggests episodic accretion. Overall, the study investigates a massive protostar candidate, driving the ∼2.7 pc H 2 outflow olc1 and undergoing episodic accretion.}, archive = {J_ApJ}, author = {O. R. Jadhav and L. K. Dewangan and Aayushi Verma and N. K. Bhadari and A. K. Maity and Saurabh Sharma and Mamta}, doi = {10.3847/1538-4357/ada388}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {133}, shortjournal = {The Astrophys. J.}, title = {Uncovering the hidden physical structures and protostellar activities in the low-metallicity s284-RE region: Results from ALMA and JWST}, volume = {980}, year = {2025}, }
• (2025). CH3OH thermal lines traces 6.7 GHz CH3OH maser variation of high-mass protostar g353.273+0.641. ApJ, 980(1), 132. (www)

  @article{ , abstract = {This study reports an analysis of the 6.7 GHz CH 3 OH maser in the high-mass protostar G353.273+0.641 (G353), utilizing data from the Tianma Radio Telescope. G353 is a possibly periodic variation in the flux density of the maser with a period of ∼330 days. Our analysis of Atacama Large Millimeter/submillimeter Array archival data identified 44 CH 3 OH transitions within the gas envelope surrounding the protostar. The CH 3 OH envelope exhibited non–local thermodynamic equilibrium (LTE) conditions during the increase phase of the flux density of the maser, then transitioning to LTE ( T ∼ 380 K) during the decay phase of the maser. This phenomenon is likely attributed to the recurrent heating of the protostellar envelope through heat waves, which are generated by the periodic luminosity oscillations of the central high-mass protostar. The propagation velocity of the heat wave is gauged to be  ∼0.02 c . These results emphasize the significance of integrating the variations in 6.7 GHz CH 3 OH masers with their surrounding circumstellar environments to advance our comprehension of high-mass star formation mechanisms.}, archive = {J_ApJ}, author = {Shi-Min Song and Xi Chen and Sheng-Yuan Liu and Jun-Ting Liu}, doi = {10.3847/1538-4357/ada4a8}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {132}, shortjournal = {The Astrophys. J.}, title = {CH3OH thermal lines traces 6.7 GHz CH3OH maser variation of high-mass protostar g353.273+0.641}, volume = {980}, year = {2025}, }
• (2025). The disk wind contribution to the gamma-ray emission from the nearby seyfert galaxy GRS 1734−292. ApJ, 980(1), 131. (www)

  @article{ , abstract = {Radio-quiet Seyfert galaxies have been detected in GeV gamma rays by the Fermi Large Area Telescope (LAT), but the origin of much of this emission is unclear. We consider the nearby example GRS 1734−292, which exhibits weak starburst and jet activities that are insufficient to explain the observed gamma-ray flux. With the first detailed multiwavelength study of this source, we demonstrate that an active galactic nucleus (AGN) disk wind can account for its gamma-ray emission. Using a lepto-hadronic emission model based on a shocked ambient medium and a shocked wind region created by an AGN accretion disk wind, we identify two viable scenarios that are consistent with the Fermi-LAT data and multiwavelength observations: a hadronic pp -dominated scenario and a leptonic external-Compton-dominated scenario. Both of these show that future observations with the Cherenkov Telescope Array and the Southern Wide-field Gamma-ray Observatory could detect TeV emission from a disk wind in GRS 1734−292. Such a detection would substantially improve our understanding of cosmic-ray acceleration efficiency in AGN disk wind systems and would establish radio-quiet Seyfert galaxies as cosmic-ray accelerators capable of reaching ultrahigh energies.}, archive = {J_ApJ}, author = {Nobuyuki Sakai and Tomoya Yamada and Yoshiyuki Inoue and Ellis R. Owen and Tomonari Michiyama and Ryota Tomaru and Yasushi Fukazawa}, doi = {10.3847/1538-4357/ada55d}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {131}, shortjournal = {The Astrophys. J.}, title = {The disk wind contribution to the gamma-ray emission from the nearby seyfert galaxy GRS 1734−292}, volume = {980}, year = {2025}, }
• (2025). Analytical and numerical methods for circumbinary disk dynamics. II. inclined disks. ApJ, 980(1), 130. (www)

  @article{ , abstract = {To gain insight into the dynamical influence of a supermassive black hole binary on a circumbinary accretion disk, we investigate the binary and viscous torque densities throughout such a disk, with emphasis on the final density distribution, particularly the size and stability of the central gap between the binary and the inner edge of the disk. We limit ourselves to the simplified case of a massless viscous thin accretion disk under the influence of the gravitational potential from a binary system whose orbital plane is inclined relative to the disk. We employ two-dimensional Newtonian hydrodynamics simulations to examine the influence of two model parameters: the mass ratio of the binary and the inclination angle between the binary and the disk. We investigate their impact on the density and torque distribution. In our analytical approach, we consider the stability of epicycles induced by the perturbative effect of the asymmetric inclined binary gravitational potential on Keplerian circular orbits. Through our simulations, we observe that certain configurations never attain a quasi-steady state, where the density profile averaged over many orbits stabilizes. This instability occurs when the inclination is close to 45°. Furthermore, we identify configurations where there is never a persistent balance between the dynamical and viscous torque densities, as well as cases where the location of this balance oscillates or exhibits other time-dependent behavior over viscous timescales. These findings have implications for understanding both the expected gravitational-wave signal and electromagnetic counterparts from supermassive black hole binaries.}, archive = {J_ApJ}, author = {Michal Pirog and Siddharth Mahesh and Sean T. McWilliams}, doi = {10.3847/1538-4357/ada55e}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {130}, shortjournal = {The Astrophys. J.}, title = {Analytical and numerical methods for circumbinary disk dynamics. II. inclined disks}, volume = {980}, year = {2025}, }
• (2025). Discovery and detailed study of the m31 classical nova AT 2023tkw: Evidence for internal shocks. ApJ, 980(1), 129. (www)

  @article{ , abstract = {We present a detailed analysis of an extragalactic slow classical nova in M31 exhibiting multiple peaks in its light curve. Spectroscopic and photometric observations were used to investigate the underlying physical processes. Shock-induced heating events resulting in the expansion and contraction of the photosphere are likely responsible for the observed multiple peaks. Deviation of the observed spectrum at the peak from the models also suggests the presence of shocks. The successive peaks occurring at increasing intervals could be due to the series of internal shocks generated near or within the photosphere. Spectral modeling suggests a low-mass white dwarf (WD) accreting slowly from a companion star. The ejecta mass, estimated from spectral analysis, is ~10 −4 M ⊙ , which is typical for a slow nova. We estimate the binary, by comparing the archival Hubble Space Telescope data and eruption properties with stellar and nova models, to comprise a 0.65 M ⊙ primary WD and a K iii cool evolved secondary star.}, archive = {J_ApJ}, author = {Judhajeet Basu and Ravi Kumar and G.C. Anupama and Sudhanshu Barway and Peter H. Hauschildt and Shatakshi Chamoli and Vishwajeet Swain and Varun Bhalero and Viraj Karambelkar and Mansi Kasliwal and Kaustav K. Das and Igor Andreoni and Avinash Singh and Rishabh Singh Teja}, doi = {10.3847/1538-4357/ada5fe}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {129}, shortjournal = {The Astrophys. J.}, title = {Discovery and detailed study of the m31 classical nova AT 2023tkw: Evidence for internal shocks}, volume = {980}, year = {2025}, }
• (2025). Predicting solar energetic particle events with time series shapelets. ApJ, 980(1), 128. (www)

  @article{ , abstract = {Solar energetic particle (SEP) events pose significant risks to both space and ground-level infrastructure, as well as to human health in space. Understanding and predicting these events are critical for mitigating their potential impacts. In this paper, we address the challenge of predicting SEP events using proton flux data. We leverage some of the most recent advances in time series data mining, such as shapelets and the matrix profile, to propose a simple and easily understandable prediction approach. Our objective is to mitigate the interpretability challenges inherent to most machine learning models and to show that other methods exist that can not only yield accurate forecasts but also facilitate exploration and insight generation within the data domain. For this purpose, we construct a multivariate time series data set consisting of proton flux data recorded by the National Oceanic and Atmospheric Administration's geosynchronous orbit Earth-observing satellite. Then, we use our proposed approach to mine shapelets and make predictions using a random forest classifier. We demonstrate that our approach rivals state-of-the-art SEP prediction, offering superior interpretability and the ability to predict SEP events before their parent eruptive flares.}, archive = {J_ApJ}, author = {Omar Bahri and Peiyu Li and Soukaïna Filali Boubrahimi and Shah Muhammad Hamdi}, doi = {10.3847/1538-4357/ada601}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {128}, shortjournal = {The Astrophys. J.}, title = {Predicting solar energetic particle events with time series shapelets}, volume = {980}, year = {2025}, }
• (2025). Spectral variations across latitudes on asteroid (3200) phaethon. ApJ, 980(1), 127. (www)

  @article{ , abstract = {3200 Phaethon is a near-Earth asteroid known to be actively emitting dust and gas when near its perihelion, and it is the target of the Japanese DESTINY+ mission. Several visible–near-IR spectra were obtained of Phaethon during 2003–2017, which have been collected together and analyzed with respect to its shape model. Using a thermal model, we examine the diurnal temperature variations across Phaethon's surface (Δ T ∼ 600 K). We find different solar radiation heating between the north and south regions, with very high surface temperatures in the south region (max peak ∼ 1050 K), while a lower temperature is found in the north region (a mean value of 760 K). Our analysis of the photometrically corrected slope suggests a latitudinal trend in surface composition. We propose that the northern region of Phaethon may be linked to unusual chondrites and naturally heated Y-82162 samples (63–125 μ m and/or chips), while the southern region shows similarities to Ivuna CI chondrites heated to 700°C (0–125 μ m). The equatorial region appears to include a mixture of materials from both hemispheres.}, archive = {J_ApJ}, author = {M. Angrisani and E. Palomba and A. Longobardo and E. Rognini and A. Migliorini and E. D’Aversa and G. Pratesi and C. Gisellu and F. Dirri and L. Piazzo and T. Arai}, doi = {10.3847/1538-4357/ada60d}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {127}, shortjournal = {The Astrophys. J.}, title = {Spectral variations across latitudes on asteroid (3200) phaethon}, volume = {980}, year = {2025}, }
• (2025). ALMA FACTS. II. large scale variations in the 12CO(J = 2 – 1) to 12CO(J = 1 – 0) line ratio in nearby galaxies. ApJ, 980(1), 126. (www)

  @article{ , abstract = {We present 12 CO( J = 1 – 0) mapping observations over ∼1/2 of the optical disk of 12 nearby galaxies from the Fundamental CO 1–0 Transition Survey of nearby galaxies (FACTS), using the ALMA Total Power array. Variations in the 12 CO( J = 2 − 1)/ 12 CO( J = 1 − 0) line ratio r 21 are investigated. The luminosity-weighted r 21 of the 11 sample galaxies ranges from 0.52 to 0.69 with an average of 0.61. We use position–velocity diagrams along the major axis and tilted ring models to separate the normal rotating galactic disk from kinematic outliers that deviate from pure circular rotation. We find that r 21 is systematically higher in outliers compared to the disk. We compare r 21 between SA, SAB, and SB galaxies, and find no significant difference in the average r 21 depending on the presence of galactic bars. We find, however, that the radial gradient in r 21 is bimodal, where a group containing all SA galaxies prefer constant or very shallow r 21 gradients out to 40% of the optical radius, while another group containing all SB galaxies have a steep r 21 gradient, decreasing by ∼20% before 40% of the optical radius, which also corresponds to the radius of the stellar bar. After this radius, these galaxies become consistent with a constant or shallow trend in r 21 . The large scale trend in r 21 can have implications for how we interpret observations made solely in the 12 CO( J = 2 − 1) line.}, archive = {J_ApJ}, author = {Shinya Komugi and Tsuyoshi Sawada and Jin Koda and Fumi Egusa and Fumiya Maeda and Akihiko Hirota and Amanda M. Lee}, doi = {10.3847/1538-4357/ada6b5}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {126}, shortjournal = {The Astrophys. J.}, title = {ALMA FACTS. II. large scale variations in the 12CO(J = 2 – 1) to 12CO(J = 1 – 0) line ratio in nearby galaxies}, volume = {980}, year = {2025}, }
• (2025). Tracing the winds: A uniform interpretation of helium escape in exoplanets from archival spectroscopic observations. ApJ, 980(1), 125. (www)

  @article{ , abstract = {Over the past decade, observations of evaporating exoplanets have become increasingly common, driven by the discovery of the near-infrared helium-triplet line as a powerful probe of atmospheric escape. This process significantly influences the evolution of exoplanets, particularly those smaller than Jupiter. Both theoretical and observational studies have aimed to determine how efficiently exoplanets convert their host star's X-ray and ultraviolet (XUV) radiation into atmospheric mass loss. In this study, we employ the open-source atmospheric escape model p-winds to systematically analyze all publicly available helium triplet spectroscopic detections related to exoplanetary atmospheric escape. Our findings indicate that the retrieved outflows strongly depend on the ratio of XUV flux to planetary density ( F XUV / ρ p ), supporting the theoretical framework of energy-limited mass loss. We constrain population-level photoevaporative efficiencies to 0.34 ± 0.13 and 0.75 ± 0.21 for hydrogen-helium fractions of 0.90 and 0.99, respectively. These results offer new insights into exoplanetary atmospheric evolution and will aid future studies on exoplanet population demographics.}, archive = {J_ApJ}, author = {Patrick McCreery and Leonardo A. Dos Santos and Néstor Espinoza and Romain Allart and James Kirk}, doi = {10.3847/1538-4357/ada6b9}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {125}, shortjournal = {The Astrophys. J.}, title = {Tracing the winds: A uniform interpretation of helium escape in exoplanets from archival spectroscopic observations}, volume = {980}, year = {2025}, }
• (2025). PSR j1947−1120: A new huntsman millisecond pulsar binary. ApJ, 980(1), 124. (www)

  @article{ , abstract = {We present the discovery of PSR J1947–1120, a new huntsman millisecond pulsar with a red giant companion star in a 10.3 day orbit. This pulsar was found via optical, X-ray, and radio follow-up of the previously unassociated γ -ray source 4FGL J1947.6–1121. PSR J1947–1120 is the second confirmed pulsar in the huntsman class and establishes this as a bona fide subclass of millisecond pulsars. We use MESA models to show that huntsman pulsars can be naturally explained as neutron star binaries whose secondaries are currently in the "red bump" region of the red giant branch, temporarily underfilling their Roche lobes and hence halting mass transfer. Huntsman pulsars offer a new view of the formation of typical millisecond pulsars, allowing novel constraints on the efficiency of mass transfer and recycling at an intermediate stage in the process.}, archive = {J_ApJ}, author = {Jay Strader and Paul S. Ray and Ryan Urquhart and Samuel J. Swihart and Laura Chomiuk and Elias Aydi and Eric C. Bellm and Kristen C. Dage and Megan E. DeCesar and Julia S. Deneva and Maura A. McLaughlin and Isabella Molina and Teresa Panurach and Kirill V. Sokolovsky}, doi = {10.3847/1538-4357/ada897}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {124}, shortjournal = {The Astrophys. J.}, title = {PSR j1947−1120: A new huntsman millisecond pulsar binary}, volume = {980}, year = {2025}, }
• (2025). The extreme-ultraviolet precursors and postcursors of solar flares. ApJ, 980(1), 123. (www)

  @article{ , abstract = {EUV brightenings are small-scale magnetic reconnection events that consistently appear before and after solar flares. However, it is not well understood how EUV precursors might foreshadow flares and what the physical connection is between the EUV signatures and flares. We studied flare-active and inactive periods in three separate studies using the Detection and EUV Flare Tracking (DEFT) tool. In Study 1, EUV signatures were identified in 200 no-flare days, in Study 2 EUV signatures before 360 flares were analyzed, and in Study 3 close to 36,000 EUV signatures were detected, and their pre- and postflare distribution and trends were studied. Our key questions were as follows: do EUV signatures occur consistently before flares, do EUV signatures occur without flares, are there flares without EUV precursors, and is it possible to forecast different magnitude flares based on preceding EUV signature trends? Study 1 showed that in no-flare periods EUV signatures were only detected 4% of the time. Study 2 showed that EUV precursors were present 92% of the time within 6 hr before ≥C-class flares. Study 3 showed that over 90% of the signatures were associated with flares (≥B class), and over 50% of all signatures were associated with ≥M-class flares. A superposed epoch analysis showed precursor frequency peaks at  ∼70 and 100 minutes before M- and X-class flares, respectively, while B- and C-class flares had no notable precursor frequency peaks. These results demonstrate the close connection between EUV signatures and flares and the significant potential EUV signatures have in improving space weather forecasting.}, archive = {J_ApJ}, author = {Larisza D. Krista}, doi = {10.3847/1538-4357/ada8a5}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {123}, shortjournal = {The Astrophys. J.}, title = {The extreme-ultraviolet precursors and postcursors of solar flares}, volume = {980}, year = {2025}, }
• (2025). Baryon pasting the uchuu light-cone simulation. ApJ, 980(1), 122. (www)

  @article{ , abstract = {We present the Baryon Pasted (BP) X-ray and thermal Sunyaev–Zel'dovich (tSZ) maps derived from the half-sky Uchuu light-cone simulation. These BP-Uchuu maps are constructed using more than 75 million dark matter halos with masses M 500 c ≥ 10 13 M ⊙ within the redshift range 0 ≤ z ≤ 2. A distinctive feature of our BP-Uchuu light-cone maps is their capability to assess the influence of both extrinsic and intrinsic scatter caused by triaxial gaseous halos and internal gas characteristics, respectively, at the map level. We show that triaxial gas drives substantial scatter in X-ray luminosities of clusters and groups, accounting for nearly half of the total scatter in core-excised measurements. Additionally, scatter in the thermal pressure and gas density profiles of halos enhances the X-ray and SZ power spectra, leading to biases in cosmological parameter estimates. These findings are statistically robust due to the extensive sky coverage and large halo sample in the BP-Uchuu maps. The BP-Uchuu maps are publicly available online via Globus ( https://app.globus.org/file-manager?origin_id=cf8dadb7-b6e9-4e2c-abc1-0813877efc13 ).}, archive = {J_ApJ}, author = {Erwin T. Lau and Daisuke Nagai and Arya Farahi and Tomoaki Ishiyama and Hironao Miyatake and Ken Osato and Masato Shirasaki}, doi = {10.3847/1538-4357/ada940}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {122}, shortjournal = {The Astrophys. J.}, title = {Baryon pasting the uchuu light-cone simulation}, volume = {980}, year = {2025}, }
• (2025). No galaxy-scale [C ii] fast outflow in the z = 6.72 red quasar HSC j1205–0000. ApJ, 980(1), 121. (www)

  @article{ , abstract = {HSC 120505.09-000027.9 (J1205–0000) is one of the highest redshift ( z = 6.72) dust-reddened quasars (red quasars) known to date. We present an improved analysis of Atacama Large Millimeter/submillimeter Array data of the [C ii ] 158 μ m line and the underlying rest-frame far-infrared (FIR) continuum emission, previously reported in T. Izumi et al. (2021b), toward J1205–0000. Red quasars are thought to be a transitional phase from an obscured starburst to a luminous blue quasar, in some cases associated with massive outflows driven by the active galactic nucleus (AGN). J1205–0000 has a high FIR luminosity, L FIR = 2.5 × 10 12 L ⊙ and a total IR luminosity of L TIR = 3.5 × 10 12 L ⊙ , corresponding to a star formation rate of  ∼528 M ⊙ yr −1 . With the [C ii ]-based dynamical mass of  ∼1 × 10 11 M ⊙ , we conclude that J1205–0000 is hosted by a starburst galaxy. In contradiction to T. Izumi et al., our improved analysis shows no hint of a broad component in the [C ii ] line spectrum. Thus there is no evidence for a host galaxy-scale fast [C ii ] outflow, despite the fact that J1205–0000 has fast nuclear ionized outflows seen in the rest-frame UV. We explore several scenarios for this discrepancy (e.g., the early phase of AGN feedback, reliability of the [C ii ] line as a tracer of outflows), and we claim that it is still too early to conclude that there is no significant negative AGN feedback on star formation in this red quasar.}, archive = {J_ApJ}, author = {Mahoshi Sawamura and Takuma Izumi and Kouichiro Nakanishi and Takeshi Okuda and Michael A. Strauss and Masatoshi Imanishi and Yoshiki Matsuoka and Yoshiki Toba and Hideki Umehata and Takuya Hashimoto and Shunsuke Baba and Tomotsugu Goto and Toshihiro Kawaguchi and Kotaro Kohno and Dragan Salak and Taiki Kawamuro and Kazushi Iwasawa and Masafusa Onoue and Chien-Hsiu Lee and Kianhong Lee}, doi = {10.3847/1538-4357/ada943}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {121}, shortjournal = {The Astrophys. J.}, title = {No galaxy-scale [C ii] fast outflow in the z = 6.72 red quasar HSC j1205–0000}, volume = {980}, year = {2025}, }
• (2025). Solar coronal mass ejection and Post–Coronal mass ejection blob formation in two-fluid simulations. ApJ, 980(1), 120. (www)

  @article{ , abstract = {A coronal mass ejection (CME) and post-CME blob phenomena in the solar atmosphere, associated with shear flow and convergent flow perturbations in the photosphere, are investigated using a resistive two-fluid (electron–ion) code. It is found that there are notable deviations between the two-fluid and previous magnetohydrodynamic simulations. In this two-fluid approach, the decoupling motions of ions and electrons leads to the emergence of an additional electric field. With expansion of a magnetic arcade associated with the footpoint shear flows, a thin current sheet is formed and a series of magnetic reconnections occurs in the lower region of the central magnetic arcade. The initial reconnection gives rise to a rising magnetic island, displaying typical CME characteristics. Subsequent reconnections produce smaller, more rapidly ascending blobs. These smaller blobs ultimately merge with the primary CME core, thereby accelerating its ascent.}, archive = {J_ApJ}, author = {J. C. Du and Z. W. Ma}, doi = {10.3847/1538-4357/ada951}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {120}, shortjournal = {The Astrophys. J.}, title = {Solar coronal mass ejection and Post–Coronal mass ejection blob formation in two-fluid simulations}, volume = {980}, year = {2025}, }
• (2025). Shaping outflows and jets by ambient pressure: A unified framework. ApJ, 980(1), 119. (www)

  @article{ , abstract = {Astrophysical outflows are ubiquitous across cosmic scales, from stellar to galactic systems. While diverse launching mechanisms have been proposed, we demonstrate that these outflows share a fundamental commonality: their morphology follows the physics of pressure-confined supersonic flows. By extending classical de Laval nozzle theory to account for ambient pressure gradients, we present a unified framework that successfully describes outflows from young stellar objects to active galactic nuclei. This simplified approach, compared to full magnetohydrodynamic treatments, captures the essential physics governing outflow shapes across different scales. Our model reveals a remarkable consistency of pressure profiles, characterized by a power-law exponent near "–2" across 6 orders of magnitude in spatial scale, independent of the internal characteristics of the outflow or the nature of the central engine. This discovery suggests a universal mechanism for outflow collimation and acceleration, bridging the gap between theoretical models and observational features across a wide range of astronomical scales.}, archive = {J_ApJ}, author = {Willem A. Baan and Tao An}, doi = {10.3847/1538-4357/ada9ea}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {119}, shortjournal = {The Astrophys. J.}, title = {Shaping outflows and jets by ambient pressure: A unified framework}, volume = {980}, year = {2025}, }
• (2025). Star formation in the lopsided galaxy arp 291. ApJ, 980(1), 118. (www)

  @article{ , abstract = {We have investigated the star formation process taking place in the lopsided galaxy Arp 291, based on narrowband images in the H α , [N ii ] λ 6583, and [O iii ] λ 5007 emission lines, obtained using the modern tunable photometer MaNGaL at the Caucasus Mountain Observatory. We have diagnosed 30 star-forming (SF) regions by means of the Baldwin–Phillips–Terlevich method. The oxygen abundance of the ionized gas in the SF regions varies in the range from 8.17 ± 0.04 to 8.47 ± 0.16 dex, which is typical for spiral and irregular galaxies, and shows an anticorrelation with the surface density of current star formation rates. Star formation in the lopsided galaxy Arp 291 occurs in separate clumps comparable in size to those observed in spiral and lenticular galaxies, at a rate typical for these types of galaxies. The clumps of current star formation are located irregularly in the distorted spiral arms of Arp 291. Possible causes of lopsidedness of the galaxy are discussed.}, archive = {J_ApJ}, author = {Irina S. Proshina and Dmitriy V. Oparin}, doi = {10.3847/1538-4357/adab73}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {118}, shortjournal = {The Astrophys. J.}, title = {Star formation in the lopsided galaxy arp 291}, volume = {980}, year = {2025}, }
• (2025). Observing supernova neutrino light curves with super-kamiokande. v. distance estimation with neutrinos. ApJ, 980(1), 117. (www)

  @article{ , abstract = {Neutrinos are pivotal signals in multimessenger observations of supernovae (SNe). Recent advancements in the analysis method of supernova (SN) neutrinos, especially in quantitative analysis, have significantly broadened scientific possibilities. This study demonstrates the feasibility of estimating distances to SNe using neutrinos. This estimation utilizes the direct relationship between the radius of a neutron star (NS) and the distance to the supernova, which is analogous to main-sequence fitting. The radius of an NS is determined with an approximate uncertainty of 10% through observations such as X-rays and gravitational waves. By integrating this information, the distance to the supernova can be estimated with an uncertainty of within 15% at a 95% confidence level. It has been established that neutrinos can pinpoint the direction of supernovae, and when combined with distance estimates, three-dimensional localization becomes achievable. This capability is vital for follow-up observations using multimessenger approaches. Moreover, more precise distance determinations to SNe through follow-up observations, such as optical observations, allow for accurate measurements of neutron-star radii. This data, via the neutron-star mass–radius relationship, could provide various insights into nuclear physics.}, archive = {J_ApJ}, author = {Yudai Suwa and Akira Harada and Masamitsu Mori and Ken’ichiro Nakazato and Ryuichiro Akaho and Masayuki Harada and Yusuke Koshio and Fumi Nakanishi and Kohsuke Sumiyoshi and Roger A. Wendell}, doi = {10.3847/1538-4357/adabe2}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {117}, shortjournal = {The Astrophys. J.}, title = {Observing supernova neutrino light curves with super-kamiokande. v. distance estimation with neutrinos}, volume = {980}, year = {2025}, }
• (2025). Solar modulation of AMS-02 daily proton and helium fluxes with modified force-field approximation models. ApJ, 980(1), 116. (www)

  @article{ , abstract = {As galactic cosmic rays (GCRs) propagate through the turbulent plasma environment within the heliosphere, they undergo a process of diffusion, drift, and energy loss, leading to a notable reduction in their flux. This is the solar modulation impact. Recently, the cosmic-ray experiment AMS-02 published daily fluxes of proton and helium for the period from 2011 May 20 to 2019 October 29 in the rigidity interval from about 1 to 100 GV, exhibiting fine time structures that correlate with solar wind properties on a daily basis. In this work, we employ three different modified force field approximation models to fit the data. By fitting to the daily proton and helium fluxes, we get the time series of solar modulation potential. We find good agreement of data and model predictions for both proton and helium with the same parameters in two modified force field approximation models. The results in this study verify that the modified force-field approximation model is a valid parameterization of the GCR spectrum also at daily timescales.}, archive = {J_ApJ}, author = {Cheng-Rui Zhu and Mei-Juan Wang}, doi = {10.3847/1538-4357/adacd8}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {116}, shortjournal = {The Astrophys. J.}, title = {Solar modulation of AMS-02 daily proton and helium fluxes with modified force-field approximation models}, volume = {980}, year = {2025}, }
• (2025). The doubly librating plutinos. ApJ, 980(1), 115. (www)

  @article{ , abstract = {Named for orbital kinship with Pluto, the Plutinos are a prominent group of Kuiper Belt objects whose orbital periods are in libration about a 3/2 ratio with Neptune's. We investigate the long-term orbital dynamics of known Plutinos, with attention to the additional libration (or lack thereof) of their argument of perihelion, g , a well-known characteristic of Pluto's orbit. We show that the g librators among the Plutinos cluster around an arc in the eccentricity–inclination parameter plane. This previously unreported dynamical structure is owed to a family of periodic orbits of the third kind in the restricted problem of three bodies, identified by Poincaré at the end of the 19th century. Approximately 16% of the currently known Plutinos exhibit g librations, a far greater fraction than the ratios of the associated libration frequencies. These results may offer new constraints for theoretical models of the dynamical history of the Plutinos and of the orbital migration history of the giant planets.}, archive = {J_ApJ}, author = {Renu Malhotra and Takashi Ito}, doi = {10.3847/1538-4357/adacd9}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {115}, shortjournal = {The Astrophys. J.}, title = {The doubly librating plutinos}, volume = {980}, year = {2025}, }
• (2025). Intrinsic pulse widths of FRB 20121102A and calculation of broadening from propagation and instrumental effects. ApJ, 980(1), 114. (www)

  @article{ , abstract = {The pulse widths of fast radio bursts are always broadened due to the scattering of the plasma medium through which the electromagnetic wave passes. The recorded pulse width will be further affected by the radio telescopes since the sampling time and the bandwidth cannot be infinitely small. In this study, we focus on the pulse widths of at least 3287 bursts detected from FRB 20121102A as of 2023 October. Various effects such as the scattering broadening, the redshift-induced broadening, and the instrumental broadening are examined. At a redshift of 0.193, the pulse width is broadened by a factor of approximately 0.16 due to cosmological time dilation. It is found that the instrumental broadening only contributes a fraction of 10 −3 –10 −1 to the observed pulse width. The scattering broadening is even smaller, which constitutes a tiny fraction of 10 −5 –10 −2 in the observed pulse width. After correcting for these broadenings, the intrinsic pulse width is derived for each burst. The maximum and minimum pulse widths at different frequencies are highlighted. The intrinsic widths of most bursts are in a narrow range of 1–10 ms, which leads to a quasi-linear correlation between the fluence and the peak flux. Additionally, the mean value and the dispersion range of intrinsic pulse width are found to scale with the central frequency as ν −1.2±0.2 and ν −1.7±0.6 , respectively.}, archive = {J_ApJ}, author = {Jia-Peng Wei and Yong-Feng Huang and Lang Cui and Xiang Liu and Jin-Jun Geng and Xue-Feng Wu}, doi = {10.3847/1538-4357/adace3}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {114}, shortjournal = {The Astrophys. J.}, title = {Intrinsic pulse widths of FRB 20121102A and calculation of broadening from propagation and instrumental effects}, volume = {980}, year = {2025}, }
• (2025). Testing the flux rope paradigm for coronal mass ejections using a three-spacecraft encounter event. ApJ, 980(1), 113. (www)

  @article{ , abstract = {We present a 3D morphological and field reconstruction of a coronal mass ejection (CME) from 2023 November 28, which hits three spacecraft near 1 au: Wind at Earth's L1 Lagrange point, STEREO-A with a longitudinal separation of 6 \mathop{.}\limits^{\unicode{x000b0}} 5 west of Earth, and Solar Orbiter (SolO) at 10 \mathop{.}\limits^{\unicode{x000b0}} 7 east of Earth. The reconstruction assumes a magnetic flux rope (MFR) structure for the CME. With this event, we test whether field tracings observed by a spacecraft passing near the central axis of a CME MFR (STEREO-A) can be used to successfully predict the field behavior seen by a spacecraft 17 ∘ away (SolO), which has a more grazing encounter with the CME. We find that the MFR model does have significant success in simultaneously reproducing the field signs and rotations seen at STEREO-A, Wind, and SolO. This provides support for the MFR paradigm for CME structure. However, the SolO measurements, which are farthest from the central axis of the MFR, show less defined MFR signatures, presumably due to a greater degree of erosion and degradation of the MFR structure far from its central axis.}, archive = {J_ApJ}, author = {Brian E. Wood and Phillip Hess}, doi = {10.3847/1538-4357/adad5c}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {113}, shortjournal = {The Astrophys. J.}, title = {Testing the flux rope paradigm for coronal mass ejections using a three-spacecraft encounter event}, volume = {980}, year = {2025}, }
• (2025). Fundamental understanding of magnetic reconnection via spiral CT scan. i. density, temperature, pressure, and method validation. ApJ, 980(1), 112. (www)

  @article{ , abstract = {For the first time, we reveal the distribution of plasma density, electron temperature, thermal pressure, and total pressure around a reconnection X-line, by using the spiral CT scan technique, which is a novel technique analogous to that in the hospital. This X-line was detected by the Magnetospheric Multiscale spacecraft and has been widely believed to host a non-guide-field reconnection in previous studies. With the help of such an advanced technique, we find that (1) the plasma density is low on the magnetosphere side but high on the magnetosheath side; (2) the electron temperature is high on the magnetosphere side but low on the magnetosheath side; (3) the thermal pressure is high near the current sheet but low away from the current sheet; (4) the total pressure in the inflow region is higher than near the current sheet. Among these findings, the first three agree with classical theories, hence validating our novel scan technique; the last one implicates that antiparallel magnetic field lines were being pushed together and the reconnection process was ongoing.}, archive = {J_ApJ}, author = {H. S. Fu and Z. Wang and J. B. Cao}, doi = {10.3847/1538-4357/adade7}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {112}, shortjournal = {The Astrophys. J.}, title = {Fundamental understanding of magnetic reconnection via spiral CT scan. i. density, temperature, pressure, and method validation}, volume = {980}, year = {2025}, }
• (2025). Spin-down of solar-mass protostars in magnetospheric accretion paradigm. ApJ, 980(1), 111. (www)

  @article{ , abstract = {Stellar spin is one of the fundamental quantities that characterize a star itself and its planetary system. Nevertheless, stellar spin-down mechanisms in protostellar and pre-main-sequence stellar phases have been a long-standing problem in star formation theory. To realize the spin-down, previous axisymmetric models based on the conventional magnetospheric paradigm have had to assume massive stellar winds or produce highly time-variable magnetospheric ejections. However, this picture has been challenged by both numerical simulations and observations. With a particular focus on the propeller regime for solar-mass stars, we propose a new picture of stellar spin-down based on our recent 3D magnetohydrodynamic simulation and stellar evolution calculation. We show that failed magnetospheric winds, unique to 3D models, significantly reduce the spin-up accretion torque, which make it easier for the star to spin-down. Additionally, the amplitude of time variability associated with magnetospheric ejections is reduced by 3D effects. Our simulation demonstrates that the star spins down by generating a conical disk wind, driven by a rotating stellar magnetosphere. Our theoretical estimates, inspired by the numerical model, suggest that the conical disk wind is likely to play a crucial role in extracting stellar angular momentum during the protostellar phase. As magnetospheric accretion is expected to occur in other accreting objects such as protogiant planets, this study will also contribute to the understanding of the angular momentum of such objects.}, archive = {J_ApJ}, author = {Shinsuke Takasao and Masanobu Kunitomo and Takeru K. Suzuki and Kazunari Iwasaki and Kengo Tomida}, doi = {10.3847/1538-4357/ada364}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {111}, shortjournal = {The Astrophys. J.}, title = {Spin-down of solar-mass protostars in magnetospheric accretion paradigm}, volume = {980}, year = {2025}, }
• (2025). Laboratory measurement of CH317OH transitions in the frequency range from 216 to 264 GHz for astronomical application. ApJ, 980(1), 110. (www)

  @article{ , abstract = {Methanol is one of the most abundant complex organic molecules in interstellar environments. Molecular lines of its rare isotopologues 12 CH 3 17 OH and 12 CH 3 18 OH therefore play a crucial role in examining the column density of 12 CH 3 16 OH, which serves as a reference for organic molecular chemistry in interstellar clouds. In this study, we have recorded the spectroscopic emission spectrum of 12 CH 3 17 OH in the frequency range between 216 and 264 GHz by making use of an emission-type millimeter and submillimeter spectrometer. We have specifically paid attention to the Q -branch transitions, which are the strongest line series in this frequency region. Among the stable oxygen isotopes, 16 O, 17 O, and 18 O of methanol, only 12 CH 3 17 OH obviously shows line profiles having double and/or triple peaks in low- J transitions, due to the nuclear quadrupole interaction. The newly obtained 12 CH 3 17 OH data will play an important role in facilitating a deeper understanding of the organic chemistry related to star and planet formation. The 12 CH 3 17 OH line data allow us to trace and constrain the isotopic ratio 17 O/ 18 O in methanol, which is efficient to investigate the galactic-scale evolution of elements. In addition, we also assigned some transitions of 13 CH 3 17 OH in the recorded spectrum.}, archive = {J_ApJ}, author = {Akemi Tamanai and Takahiro Oyama and Yoshimasa Watanabe and Takeshi Sakai and Riouhei Nakatani and Shaoshan Zeng and Isabelle Kleiner and Nami Sakai}, doi = {10.3847/1538-4357/ad9b16}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {110}, shortjournal = {The Astrophys. J.}, title = {Laboratory measurement of CH317OH transitions in the frequency range from 216 to 264 GHz for astronomical application}, volume = {980}, year = {2025}, }
• (2025). Formation of stripped stars from stellar collisions in galactic nuclei. ApJ, 980(1), 109. (www)

  @article{ , abstract = {Tidal disruption events (TDEs) are an important way to probe the properties of stellar populations surrounding supermassive black holes. The observed spectra of several TDEs, such as ASASSN-14li, show high nitrogen-to-carbon (N/C) abundance ratios, leading to questions about their progenitors. Disrupting an intermediate- or high-mass star that has undergone CNO processing, increasing the nitrogen in its core, could lead to an enhanced nitrogen TDE. Galactic nuclei present a conducive environment for high-velocity stellar collisions that can lead to high mass loss, stripping the carbon- and hydrogen-rich envelopes of the stars and leaving behind the enhanced nitrogen cores. TDEs of these stripped stars may therefore exhibit even more extreme nitrogen enhancement. Using the smoothed particle hydrodynamics code StarSmasher , we provide a parameter space study of high-velocity stellar collisions involving intermediate-mass stars, analyzing the composition of the collision products. We conclude that high-velocity stellar collisions can form products that have abundance ratios similar to those observed in the motivating TDEs. Furthermore, we show that stars which have not experienced high CNO processing can yield low-mass collision products that retain even higher N/C abundance ratios. We analytically estimate the mass fallback for a typical TDE of several collision products to demonstrate consistency between our models and TDE observations. Lastly, we discuss how the extended collision products, with high central to average density ratios, can be related to repeated partial TDEs like ASASSN-14ko and G objects in the Galactic center.}, archive = {J_ApJ}, author = {Charles F. A. Gibson and Fulya Kiroğlu and James C. Lombardi and Sanaea C. Rose and Hans D. Vanderzyden and Brenna Mockler and Monica Gallegos-Garcia and Kyle Kremer and Enrico Ramirez-Ruiz and Frederic A. Rasio}, doi = {10.3847/1538-4357/ad9b80}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {109}, shortjournal = {The Astrophys. J.}, title = {Formation of stripped stars from stellar collisions in galactic nuclei}, volume = {980}, year = {2025}, }
• (2025). Tackling the problem of distributional shifts: Correcting misspecified, high-dimensional data-driven priors for inverse problems. ApJ, 980(1), 108. (www)

  @article{ , abstract = {Bayesian inference for inverse problems hinges critically on the choice of priors. In the absence of specific prior information, population-level distributions can serve as effective priors for parameters of interest. With the advent of machine learning, the use of data-driven population-level distributions (encoded, e.g., in a trained deep neural network) as priors is emerging as an appealing alternative to simple parametric priors in a variety of inverse problems. However, in many astrophysical applications it is often difficult or even impossible to acquire independent and identically distributed samples from the underlying data-generating process of interest to train these models. In these cases, corrupted data or a surrogate, e.g., a simulator, is often used to produce training samples, meaning that there is a risk of obtaining misspecified priors. This, in turn, can bias the inferred posteriors in ways that are difficult to quantify, which limits the potential applicability of these models in real-world scenarios. In this work, we propose addressing this issue by iteratively updating the population-level distributions by retraining the model with posterior samples from different sets of observations, and we showcase the potential of this method on the problem of background image reconstruction in strong gravitational lensing when score-based models are used as data-driven priors. We show that, starting from a misspecified prior distribution, the updated distribution becomes progressively closer to the underlying population-level distribution, and the resulting posterior samples exhibit reduced bias after several updates.}, archive = {J_ApJ}, author = {Gabriel Missael Barco and Alexandre Adam and Connor Stone and Yashar Hezaveh and Laurence Perreault-Levasseur}, doi = {10.3847/1538-4357/ad9b92}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {108}, shortjournal = {The Astrophys. J.}, title = {Tackling the problem of distributional shifts: Correcting misspecified, high-dimensional data-driven priors for inverse problems}, volume = {980}, year = {2025}, }
• (2025). Minor-merger-induced star formation rejuvenation in an elliptical radio-loud quasar host, 3C 59. ApJ, 980(1), 107. (www)

  @article{ , abstract = {We report a rare case where an elliptical radio-loud quasar host, 3C 59, rejuvenates star formation activity through minor mergers with its nearby satellite galaxies. The inferred star formation history of 3C 59 has shown significant star formation rejuvenation within the past 500 Myr, before which it remained rather quiescent for most of the cosmic time. The three nearest satellite galaxies of 3C 59 exhibit significant morphological disturbances, and two of them present strong tidal tails pointing toward 3C 59. In addition, all the satellite galaxies within a projected distance of 200 kpc show low star formation activities. They also have systematically lower effective radius ( R e ) than local late-type galaxies, while 3C 59 has significantly larger R e than both early- and late-type galaxies. All these features suggest that ongoing minor mergers between 3C 59 and its nearby satellites could be causing gas to flow into 3C 59, which induces the star formation rejuvenation and possibly also triggers the quasar activity. The enormous power from the large-scale radio jet of 3C 59 may in turn help keep the halo hot, prevent gas cooling, and further reduce star formation in its satellite galaxies. These results provide important insights into the mass and size growth of central galaxies and star formation quenching of satellite galaxies in galaxy groups.}, archive = {J_ApJ}, author = {Yijun Wang and Tao Wang and Ke Xu and Junjie Mao and Yerong Xu and Zheng Zhou}, doi = {10.3847/1538-4357/ada033}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {107}, shortjournal = {The Astrophys. J.}, title = {Minor-merger-induced star formation rejuvenation in an elliptical radio-loud quasar host, 3C 59}, volume = {980}, year = {2025}, }
• (2025). Solar modulation of low-energy cosmic-ray nitrogen and its comparison with oxygen. ApJ, 980(1), 106. (www)

  @article{ , abstract = {The heliospheric environment is very complex and filled with diverse high-energy particles from various origins, and among these particles, cosmic rays (CRs), including anomalous and Galactic components (ACRs and GCRs), are unique as they originate from beyond the solar system. Due to their stable and long-lasting presence in the heliosphere, the study of CRs is crucial for protecting humanity and other lifeforms against the hazards of high-energy radiation. In this work, we aim to study the prolonged changes in CR nitrogen, a fundamental element that constitutes amino acids, using the measurements from the Advanced Composition Explorer (ACE) spacecraft. The comparison of solar modulation on CR nitrogen and oxygen is also made using the yearly averaged ACE observations. The ACR nitrogen has a more even spectrum than ACR oxygen while the spectrum of GCR nitrogen is more abrupt than GCR oxygen. Further model results indicate that GCR nitrogen and oxygen undergo comparable modulation processes within the heliosphere and the slight difference between the observed power-law indices of nitrogen and oxygen spectrum is due to the distinct local interstellar spectrum of the two species. Besides, an analysis is made to explain the observed more flattened ACR spectrum of nitrogen than oxygen caused by the slightly different charge-to-mass ratio Z / A .}, archive = {J_ApJ}, author = {Yun Li and Xiaoping Zhang and Shuai Fu and Zhenning Shen and Yi Xu and Haoyu Lu and Jinbin Cao and Tianle Zhu}, doi = {10.3847/1538-4357/ada279}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {106}, shortjournal = {The Astrophys. J.}, title = {Solar modulation of low-energy cosmic-ray nitrogen and its comparison with oxygen}, volume = {980}, year = {2025}, }
• (2025). Synthetic modeling of polarized dust emission in intermediate-mass YSOs. i. constraining the role of iron inclusions and inelastic relaxation on grain alignment with ALMA polarization. ApJ, 980(1), 105. (www)

  @article{ , abstract = {Iron inclusions embedded inside dust grains play a crucial role in both internal alignment (IA) via Barnett relaxation and external alignment via the MAgnetically Enhanced RAdiative Torque (MRAT) mechanism. Moreover, inelastic relaxation is predicted to dominate over Barnett relaxation in driving the IA of micron-sized grains and very large grains (VLGs) above 10 μ m. Yet, a detailed modeling of polarized thermal dust emission from Class 0/I young stellar objects (YSOs) taking into account these effects and their observational constraints is still lacking. In this paper, we update the POLARIS code and use it to perform synthetic dust polarization modeling for MHD simulations of an intermediate-mass YSOs. Results will be post-processed with CASA to confront Atacama Large Millimeter/submillimeter Array (ALMA) polarimetric observations. We found that to reproduce the high polarization degree of p ∼ 5%–30% observed in protostellar envelopes by ALMA, micron-sized grains and VLGs must contain iron inclusions with N cl ∼ 5–10 3 iron atoms per cluster, assuming 30% of iron abundance locked inside dust grains under the cluster form. Inside the inner ∼500 au region, inelastic relaxation must participate in driving the grain IA, and grains must contain larger iron inclusions of N cl ∼ 10 2 –10 4 and grow beyond ≥10 μ m to reproduce ∼3%–10% of dust polarization observed by ALMA. But given such a combination, the IA and MRAT efficiency acting on VLGs still decreases toward the center, inducing the decrease of p (%) with increasing gas density, reaching p ∼ 1% inside the disk.}, archive = {J_ApJ}, author = {Nguyen Chau Giang and V. J. M. Le Gouellec and Thiem Hoang and A. J. Maury and P. Hennebelle}, doi = {10.3847/1538-4357/ada3cf}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {105}, shortjournal = {The Astrophys. J.}, title = {Synthetic modeling of polarized dust emission in intermediate-mass YSOs. i. constraining the role of iron inclusions and inelastic relaxation on grain alignment with ALMA polarization}, volume = {980}, year = {2025}, }
• (2025). Cluster candidates with massive quiescent galaxies at z ∼ 2. ApJ, 980(1), 104. (www)

  @article{ , abstract = {Galaxy clusters are crucial to understanding the role of the environment in galaxy evolution. However, due to their rarity, only a limited number of clusters have been identified at z ≳ 2. In this paper, we report a discovery of seven cluster candidates with massive quiescent galaxies at z ∼ 2 in the 3.5 deg 2 area of the XMM Large Scale Structure field, roughly doubling the known cluster sample at this frontier redshift if confirmed. We construct a photometric redshift catalog based on deep ( i ∼ 26, K s ∼ 24) multiwavelength photometry from the u * band to the K band gathered from the Hyper Suprime-Cam Subaru Strategic Program and other collaborative/public surveys. We adopt a Gaussian kernel density estimate with two different spatial scales (10'' and 60'') to draw a density map of massive ( \mathrm{log}({M}_{* }/{M}_{\odot })\gt 10.5 ) and quiescent ( \mathrm{log}(\mathrm{sSFR}\,[{\mathrm{yr}}^{-1}])\lt -10 ) galaxies at z ∼ 2. Then, we identify seven prominent overdensities. These candidates show clear red sequences in color–magnitude diagrams ( z − H versus H ). Moreover, one of them shows an extended X-ray emission with L X = (1.46 ± 0.35) × 10 44 erg s −1 , suggesting its virialized nature. There is no clear evidence of enhancement nor suppression of the star formation rate of the main-sequence galaxies in the clusters. We find that cluster galaxies have a higher fraction of transition population with -10.5\lt \mathrm{log}(\mathrm{sSFR}\,[{\mathrm{yr}}^{-1}])\lt -10 (12%) than the field (2%), which implies the ongoing star formation quenching. The quiescent fraction in the cluster candidates also exceeds that in the field. We confirm that the excess of a quiescent fraction is larger for higher-mass galaxies. This is the first statistical evidence for the mass-dependent environmental quenching at work in clusters even at z ∼ 2.}, archive = {J_ApJ}, author = {Tomokazu Kiyota and Makoto Ando and Masayuki Tanaka and Alexis Finoguenov and Sadman Shariar Ali and Jean Coupon and Guillaume Desprez and Stephen Gwyn and Marcin Sawicki and Rhythm Shimakawa}, doi = {10.3847/1538-4357/ada5f4}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {104}, shortjournal = {The Astrophys. J.}, title = {Cluster candidates with massive quiescent galaxies at z ∼ 2}, volume = {980}, year = {2025}, }
• (2025). Assessing the impact of binary systems on microlensing using SPISEA and PopSyCLE population simulations. ApJ, 980(1), 103. (www)

  @article{ , abstract = {Gravitational microlensing provides a unique opportunity to probe the mass distribution of stars, black holes, and other objects in the Milky Way. Population simulations are necessary to interpret results from microlensing surveys. The contribution from binary objects is often neglected or minimized in analysis of observations and simulations despite the high percentage of binary systems and microlensing's ability to probe binaries. To simulate the population effects, we added multiple systems to Stellar Population Interface for Stellar Evolution and Atmospheres ( SPISEA ), which simulates stellar clusters. We then inject these multiples into Population Synthesis for Compact-object Lensing Events ( PopSyCLE ), which simulates Milky Way microlensing surveys. When making OGLE observational selection criteria, we find that 55% of observed microlensing events involve a binary system. Specifically, 14.5% of events have a multiple lens and a single source, 31.7% have a single lens and a multiple source, and 8.8% have a multiple lens and a multiple source. The majority of these events have photometric light curves that appear single and are fit well by a single-lens, single-source model. This suggests that binary source and binary lens−binary source models should be included more frequently in event analysis. The mean Einstein crossing time shifts from 19.1 days for single events only to 21.3 days for single and multiple events, after cutting binary events with multiple peaks. The Einstein crossing time distribution of single and single-peaked multiple events is better aligned with observed distributions from OGLE than singles alone, indicating that multiple systems are a significant missing piece between simulations and reality.}, archive = {J_ApJ}, author = {Natasha S. Abrams and Jessica R. Lu and Casey Y. Lam and Michael S. Medford and Matthew W. Hosek and Sam Rose}, doi = {10.3847/1538-4357/ada5f9}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {103}, shortjournal = {The Astrophys. J.}, title = {Assessing the impact of binary systems on microlensing using SPISEA and PopSyCLE population simulations}, volume = {980}, year = {2025}, }
• (2025). Investigating the efficacy of topologically derived time series for flare forecasting. i. data set preparation. ApJ, 980(1), 102. (www)

  @article{ , abstract = {The accurate forecasting of solar flares is considered a key goal within the solar physics and space weather communities. There is significant potential for flare prediction to be improved by incorporating topological fluxes of magnetogram data sets, without the need to invoke three-dimensional magnetic field extrapolations. Topological quantities such as magnetic helicity and magnetic winding have shown significant potential toward this aim, and provide spatiotemporal information about the complexity of active region magnetic fields. This study develops time series that are derived from the spatial fluxes of helicity and winding that show significant potential for solar flare prediction. It is demonstrated that time-series signals, which correlate with flare onset times, also exhibit clear spatial correlations with eruptive activity, establishing a potential causal relationship. A significant database of helicity and winding fluxes and associated time series across 144 active regions is generated using Space-Weather HMI Active Region Patches data processed with the Active Region Topology (or ARTop) code that forms the basis of the time-series and spatial investigations conducted here. We find that a number of time series in this data set often exhibit extremal signals that occur 1–8 hr before a flare. This publicly available living data set will allow users to incorporate these data into their own flare prediction algorithms.}, archive = {J_ApJ}, author = {Thomas Williams and Christopher B. Prior and David MacTaggart}, doi = {10.3847/1538-4357/ada600}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {102}, shortjournal = {The Astrophys. J.}, title = {Investigating the efficacy of topologically derived time series for flare forecasting. i. data set preparation}, volume = {980}, year = {2025}, }
• (2025). Tracking star-forming cores as mass reservoirs in clustered and isolated regions using numerical passive tracer particles. ApJ, 980(1), 101. (www)

  @article{ , abstract = {Understanding the physical properties of star-forming cores as mass reservoirs for protostars and the impact of turbulence is crucial in star formation studies. We implemented passive tracer particles in clump-scale numerical simulations with turbulence strengths of {{ \mathcal M }}_{{\rm{rms}}}=2,10 . Unlike core identification methods used in observational studies, we identified 260 star-forming cores using a new method based on tracer particles falling onto protostars. Our findings reveal that star-forming cores do not necessarily coincide with high-density regions when nearby stars are present, as gas selectively accretes onto protostars, leading to clumpy, fragmented structures. We calculated convex hull cores from star-forming cores and defined their filling factors. Regardless of turbulence strength, convex hull cores with lower filling factors tend to contain more protostars and have larger masses and sizes, indicating that cores in clustered regions are more massive and larger than those in isolated regions. Thus, the filling factor serves as a key indicator for distinguishing between isolated and clustered star-forming regions and may provide insights into the star formation processes within clustered regions. We also found that most convex hull cores are gravitationally bound. However, in the {{ \mathcal M }}_{{\rm{rms}}}=10 model, there are more low-mass, unbound convex hull cores compared to the {{ \mathcal M }}_{{\rm{rms}}}=2 model. In the {{ \mathcal M }}_{{\rm{rms}}}=10 model, 16% of the convex hull cores are unbound, which may be explained by the inertial-inflow model. These findings highlight the influence of turbulence strength on the mass and gravitational stability of cores.}, archive = {J_ApJ}, author = {Shingo Nozaki and Hajime Fukushima and Kazuki Tokuda and Masahiro N. Machida}, doi = {10.3847/1538-4357/ada602}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {101}, shortjournal = {The Astrophys. J.}, title = {Tracking star-forming cores as mass reservoirs in clustered and isolated regions using numerical passive tracer particles}, volume = {980}, year = {2025}, }
• (2025). A systematic study of inverting overlappograms: MaGIXS—A case study. ApJ, 980(1), 100. (www)

  @article{ , abstract = {Slitless (or wide-field) imaging spectroscopy provides simultaneous imaging and spectral information from a wide field of view, allowing for rapid spectroscopic data collection from extended sources. Depending on the size of the extended source, combined with the spatial resolution and spectral dispersion of the instrument, there may be locations in the focal plane where spectral lines from different spatial locations overlap on the detector. An unfolding method is successfully developed and demonstrated on the recent rocket flight of the Marshall Grazing Incidence X-ray Spectrometer, which observed several strong emission lines in the 8–30 Å wavelength range from two X-ray bright points and a portion of an active region. In this paper, we present a systematic investigation of the parameters that control and optimize the inversion method for unfolding slitless spectrograph data.}, archive = {J_ApJ}, author = {P. S. Athiray and Arthur Hochedez and Amy R. Winebarger and Dyana Beabout}, doi = {10.3847/1538-4357/ada6b6}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {100}, shortjournal = {The Astrophys. J.}, title = {A systematic study of inverting overlappograms: MaGIXS—A case study}, volume = {980}, year = {2025}, }
• (2025). The timing and spectral properties of the 2022 outburst of SGR j1935+2154 observed with NICER. ApJ, 980(1), 99. (www)

  @article{ , abstract = {The magnetar SGR J1935+2154 entered a new active episode on 2022 October 10, with X-ray bursts and enhanced persistent emission. At the tail of a high burst rate interval, lasting several hours, radio bursts were detected, revealing the connection between the X-ray activities and radio emissions. We analyzed observations of SGR J1935+2154 for nearly 3 months, using data from the Neutron Star Interior Composition Explorer. We report the timing and spectral results following the onset of this outburst. In general, the X-ray flux of the persistent emission decays exponentially. While a flare is evident on the light curve, a fast radio burst (FRB) was detected immediately following the peak of this flare. We found a phase jump in the pulse profile, with a deviation of a 0.16 ± 0.03 phase, which is related to the glitch. The spectra are well fit with the combination of a blackbody and a power-law (PL) model. The decay of the outburst is dominated by the drop in the nonthermal component, which also leads to an increase in thermal proportion. The photon index of the PL is inversely correlated with both the unabsorbed flux and the burst rate. We find that unlike the large variety of the persistent emission around FRB 221014, the X-ray properties are very stable when FRBs 221021 and 221201 happened. These results manifest the connection between the glitch, phase jump, X-ray burst, and radio burst, crucial for studying the mutation in twisted magnetic fields and constraining the trigger mechanism of radio bursts.}, archive = {J_ApJ}, author = {Fu Yu-Cong and Lin Lin and Ge Ming-Yu and Enoto Teruaki and Hu Chin-Ping and Younes George and Göǧüş Ersin and Malacaria Christian}, doi = {10.3847/1538-4357/ada936}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {99}, shortjournal = {The Astrophys. J.}, title = {The timing and spectral properties of the 2022 outburst of SGR j1935+2154 observed with NICER}, volume = {980}, year = {2025}, }
• (2025). Modeling the saddle-like GeV–TeV spectrum of HESS j1809–193: Gamma rays arising from reverse-shocked pulsar wind nebula?. ApJ, 980(1), 98. (www)

  @article{ , abstract = {The evolution of pulsar wind nebulae (PWNe) could be expected to leave imprints in gamma rays. We suggest that the intriguing GeV–TeV spectral energy distribution (SED) of HESS J1809–193 and Fermi-LAT source J1810.3–1925e is very likely to be the gamma-ray signature of PWN J1809–193 in light of the scenario that the PWN was struck by the reverse shock of the parent supernova remnant. Based on the evolutionary theory of PWNe, we consider that, when the PWN was disrupted during a collision by the reverse shock, some VHE electrons escaped impulsively. The remaining electrons stayed in the relic PWN, which was displaced from the pulsar. The VHE part of the remaining electrons was depleted by the strong magnetic field that was enhanced by the reverse shock compression in the reverberation stage, leaving the other part of them generating GeV emission. The particles injected from the pulsar after the disruption enter the relic PWN through the newly formed tunnel called the cocoon. The gamma-ray emission from the escaped electrons can account for the TeV spectrum of component A of HESS J1809–193 or the TeV halo, while the electrons remaining after disruption can account for the GeV spectrum of J1810.3–1925e. Thus, the combination of contributions from these two populations of electrons naturally reproduces the saddle-like SED of HESS 1809–193 and J1810.3–1925e from 5 GeV to 30 TeV, together with the spectral hardening around 100 GeV. We also show that the post-disruption injection of electrons can explain the spectrum of the relatively faint gamma-ray emission of component B of HESS J1809–193.}, archive = {J_ApJ}, author = {Jiaxu Sun and Yang Chen and Yiwei Bao and Xiao Zhang and Xin Zhou}, doi = {10.3847/1538-4357/ada93e}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {98}, shortjournal = {The Astrophys. J.}, title = {Modeling the saddle-like GeV–TeV spectrum of HESS j1809–193: Gamma rays arising from reverse-shocked pulsar wind nebula?}, volume = {980}, year = {2025}, }
• (2025). First detection of radio emission from the intermediate-mass black hole in POX 52: Deep multiband observations with ATCA and VLA. ApJ, 980(1), 97. (www)

  @article{ , abstract = {We present the first multiband centimeter detection of POX 52, a nearby dwarf galaxy believed to harbor a robust intermediate-mass black hole. We conducted the deep observations using the Australia Telescope Compact Array (ATCA), spanning frequencies from 4.5 to 10 GHz, as well as the sensitive observations from the Karl G. Jansky Very Large Array (VLA) operating in its most extended A configuration at S band (2–4 GHz) and C band (4–8 GHz). In the ATCA observations, the source shows a compact morphology, with only one direction marginally resolved. The higher resolution of the VLA allowed us to slightly resolve the source, fitting it well with a two-dimensional Gaussian model. The detected radio emission confirms the presence of active galactic nucleus (AGN) activity, indicating either a low-power jet or AGN-driven winds/outflows. Our dual-epoch observations with ATCA and VLA, together with previous nondetection flux density upper limits, reveal radio emission variability spanning two decades. In addition, we find that POX 52 aligns well with the low-mass extension of the fundamental plane for high-accretion, radio-quiet massive AGNs.}, archive = {J_ApJ}, author = {Qi Yuan and Hengxiao Guo and Minfeng Gu and Jamie Stevens and Philip G. Edwards and Yongjun Chen and Wenwen Zuo and Jingbo Sun and Jun Yang and Paulina Lira and Tao An and Renzhi Su and Yuanqi Liu and Yijun Wang and Ning Chang and Pengfei Jiang and Ming Zhang}, doi = {10.3847/1538-4357/ada946}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {97}, shortjournal = {The Astrophys. J.}, title = {First detection of radio emission from the intermediate-mass black hole in POX 52: Deep multiband observations with ATCA and VLA}, volume = {980}, year = {2025}, }
• (2025). Delay of near-relativistic electrons with respect to type III radio bursts throughout the inner heliosphere. ApJ, 980(1), 96. (www)

  @article{ , abstract = {Energetic electrons accelerated by solar eruptive events are frequently observed to have inferred injection times that appear significantly delayed with respect to electromagnetic emission including type III radio bursts. This is noteworthy because type III radio emission is produced by streaming suprathermal electrons, and thus this observed delay implies either a delayed injection/release of higher-energy electrons, compared with the suprathermal population, and/or a delay of the electrons observed in situ in transit through the interplanetary medium. A number of studies have investigated these delays with spacecraft located at 1 au. In this study, we examine energetic electron onsets and type III radio bursts observed by the Integrated Science Investigation of the Sun (IS⊙IS) and the FIELDS Radio Frequency Spectrometer instrument on Parker Solar Probe at a variety of heliocentric distances. With these observations, we can uniquely decouple the effects of acceleration and transport and shed light on the source of these delays. We present a survey of electron events observed by IS⊙IS within the first ∼6 yr of the mission, including their delays with respect to type III emission between ∼0.1 and 0.8 au. These results suggest that energetic electron delays with respect to type III radio bursts are not purely produced by a delayed injection/release as has been suggested, implying that transport processes play a role.}, archive = {J_ApJ}, author = {J. G. Mitchell and E. R. Christian and G. A. de Nolfo and C. M. S. Cohen and M. E. Hill and A. Kouloumvakos and A. W. Labrador and R. A. Leske and D. J. McComas and R. L. McNutt and D. G. Mitchell and M. Shen and N. A. Schwadron and M. E. Wiedenbeck and S. D. Bale and M. Pulupa}, doi = {10.3847/1538-4357/adaa7c}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {96}, shortjournal = {The Astrophys. J.}, title = {Delay of near-relativistic electrons with respect to type III radio bursts throughout the inner heliosphere}, volume = {980}, year = {2025}, }
• (2025). Fluctuations driven by multicomponent pickup ion distributions in the outer heliosheath. ApJ, 980(1), 95. (www)

  @article{ , abstract = {The stability of a realistic multicomponent pickup ion (PUI) velocity distribution derived from a global model of neutral atoms in the heliosphere, which treats hydrogen and helium atoms self-consistently and includes equations for electrons and helium ions, is investigated using linear instability analysis and hybrid simulations. Linear instability analysis shows that the excited oblique mirror waves and the parallel/quasi-parallel Alfvén-cyclotron (AC) waves have lower growth rates than those obtained previously by A. Mousavi et al. for the PUI velocity distributions given by J. Heerikhuisen et al. The PUI scattering by each of the two modes alone is studied. In contrast to the previous investigations, our current simulations using the updated realistic distributions indicate that mirror waves alone do not effectively scatter PUIs in pitch angle. Instead, they primarily contribute to reducing the thermal spread anisotropy of the PUIs originating from the neutral solar wind. The unstable AC waves exhibit lower growth rates but higher saturation levels than the mirror waves. Two-dimensional (2D) simulation results show that when all unstable waves are present, the predominant contributor to the fluctuating magnetic field energy is the AC mode. The AC waves quickly scatter the PUIs with pitch angles away from 90 ∘ toward isotropy, while the PUIs near 90 ∘ pitch angle maintain a degree of anisotropy within our simulation timeframe. Moreover, several 1D and 2D hybrid simulations with different numbers of particles per cell are performed to examine the impact of numerical noise on PUI scattering. Finally, the implications of these results for the Interstellar Boundary Explorer energetic neutral atom ribbon are discussed.}, archive = {J_ApJ}, author = {Ameneh Mousavi and Vadim Roytershteyn and Federico Fraternale and Nikolai Pogorelov}, doi = {10.3847/1538-4357/adaaf4}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {95}, shortjournal = {The Astrophys. J.}, title = {Fluctuations driven by multicomponent pickup ion distributions in the outer heliosheath}, volume = {980}, year = {2025}, }
• (2025). Dust dynamics in radially convective regions of protoplanetary disks. ApJ, 980(1), 94. (www)

  @article{ , abstract = {Hydrodynamic instabilities likely operate in protoplanetary disks. One candidate, convective overstability (COS), can be triggered in regions with a negative radial entropy gradient. The ensuing turbulence and flow structures are expected to affect dust dynamics directly. We revisit the interaction between dust and the COS with high-resolution spectral simulations in the unstratified, axisymmetric Boussinesq shearing box framework. We find zonal flows, or pressure bumps, formed by the COS trap dust, as expected, but dust densities increase at most by a factor of O (10) over its background value due to the zonal flows' unsteady nature. Furthermore, dust feedback can impede the formation of zonal flows, even at small dust-to-gas ratios ∼ O (0.1). We interpret this phenomenon as a competition between the negative gas angular momentum flux associated with zonal flow formation and the positive dust angular momentum flux associated with its drift toward pressure maxima. Dust concentration significantly weakens when a large-scale radial pressure gradient induces a background dust drift. Ultimately, we find that dust concentration by COS-induced zonal flows is limited to ≲ 1. Whether this can be improved under more realistic geometries must be addressed with stratified and full 3D simulations at equivalent resolutions.}, archive = {J_ApJ}, author = {Min-Kai Lin and Marius Lehmann}, doi = {10.3847/1538-4357/adabe6}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {94}, shortjournal = {The Astrophys. J.}, title = {Dust dynamics in radially convective regions of protoplanetary disks}, volume = {980}, year = {2025}, }
• (2025). Constraints on the variation of the fine-structure constant at 3 < z < 10 with JWST emission-line galaxies. ApJ, 980(1), 93. (www)

  @article{ , abstract = {We present constraints on the spacetime variation of the fine-structure constant α at redshifts 2.5 ≤ z < 9.5 using JWST emission-line galaxies (ELGs). The galaxy sample consists of 621 high-quality spectra with strong and narrow [O iii ] λλ 4959,5007 doublet emission lines from 578 galaxies, including 232 spectra at z > 5. The [O iii ] doublet lines are arguably the best emission lines to probe the variation in α . We divide our sample into six subsamples based on redshift and calculate the relative variation Δ α / α for the individual subsamples. The calculated Δ α / α values are consistent with zero within 1 σ at all redshifts, suggesting no time variation in α above a level of (1–2) × 10 −4 (1 σ ) in the past 13.2 billion yr. When the whole sample is combined, the constraint is improved to be Δ α / α = (0.2 ± 0.7) × 10 −4 . We further test the spatial variation in α using four subsamples of galaxies in four different directions on the sky. The measured Δ α / α values are consistent with zero at a 1 σ level of ∼2 × 10 −4 . While the constraints in this work are not as stringent as those from lower-redshift quasar absorption lines in previous studies, this work uses an independent tracer and provides the first constraints on Δ α / α at the highest redshifts. With the growing number of ELGs from JWST, we expect to achieve stronger constraints in the future.}, archive = {J_ApJ}, author = {Linhua Jiang and Shuqi Fu and Feige Wang and Sarah E. I. Bosman and Zheng Cai and Hyunsung D. Jun and Zhiwei Pan and Fengwu Sun and Jinyi Yang and Huanian Zhang}, doi = {10.3847/1538-4357/adad5b}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {93}, shortjournal = {The Astrophys. J.}, title = {Constraints on the variation of the fine-structure constant at 3 < z < 10 with JWST emission-line galaxies}, volume = {980}, year = {2025}, }
• (2025). Constraints on relativistic jets from the fast X-ray transient 210423 using prompt radio follow-up observations. ApJ, 980(1), 92. (www)

  @article{ , abstract = {Fast X-ray transients (FXTs) are a new observational class of phenomena with no clear physical origin. This is at least partially a consequence of limited multiwavelength follow-up of this class of transients in real time. Here we present deep optical ( g - and i -band) photometry with Keck, and prompt radio observations with the Very Large Array of FXT 210423 obtained at δ t ≈ 14–36 days since the X-ray trigger. We use these multiband observations, combined with publicly available data sets, to constrain the presence and physical properties of on-axis and off-axis relativistic jets such as those that can be launched by neutron star mergers and tidal disruption events, which are among the proposed theoretical scenarios of FXTs. Considering a wide range of possible redshifts z ≤ 3.5, circumstellar medium density n = 10 −6 –10 −1 cm −3 , and isotropic-equivalent jet kinetic energy E k ,iso = 10 48 –10 55 erg, we find that we can rule out wide jets with opening angle θ j = 15° viewed within 10° off-axis. For more collimated jets ( θ j = 3°) we can only rule out on-axis ( θ obs = 0°) orientations. This study highlights the constraining power of prompt multiwavelength observations of FXTs discovered in real time by current (e.g., Einstein Probe) and future facilities.}, archive = {J_ApJ}, author = {Dina Ibrahimzade and R. Margutti and J. S. Bright and P. Blanchard and K. Paterson and D. Lin and H. Sears and A. Polzin and I. Andreoni and G. Schroeder and K. D. Alexander and E. Berger and D. L. Coppejans and A. Hajela and J. Irwin and T. Laskar and B. D. Metzger and J. C. Rastinejad and L. Rhodes}, doi = {10.3847/1538-4357/ad9397}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {92}, shortjournal = {The Astrophys. J.}, title = {Constraints on relativistic jets from the fast X-ray transient 210423 using prompt radio follow-up observations}, volume = {980}, year = {2025}, }
• (2025). Galaxies lighting up: Discovery of seventy new turn-on changing-look active galactic nuclei. ApJ, 980(1), 91. (www)

  @article{ , abstract = {"Changing-look active galactic nuclei" (CL AGN) show dramatic, rapid changes in optical/UV continuum and broad-line emission. The majority of CL AGN have been found dimming as "turn-off" CL AGN because most selection methods start from samples of spectroscopically confirmed quasars. We present here a sample of 82 spectroscopically confirmed "turn-on" CL AGN, 70 of which are newly identified. The turn-on CL AGN are selected from spectroscopically classified galaxies with subsequent significant and dramatic variability in both the optical and mid-infrared bands, indicating a mechanism of changing accretion rate of the supermassive black holes (BHs) rather than variable obscuration. Based on their bright state Eddington ratios, turn-on CL AGN are associated with lower accretion rates compared to turn-off CL AGN or typical Sloan Digital Sky Survey quasars with similar redshift and magnitude distributions, even though turn-on CL AGN have lower BH masses. Most turn-on CL AGN reside in host galaxies that follow local relations between the central BH mass and host galaxy properties, such as stellar mass and velocity dispersion. However, their host galaxies have higher mass than normal inactive galaxies, with star formation rates more similar to hosts of Type 2 AGN than to the overall galaxy population.}, archive = {J_ApJ}, author = {Qian Yang and Paul J. Green and Xue-Bing Wu and Michael Eracleous and Linhua Jiang and Yuming Fu}, doi = {10.3847/1538-4357/ad94ed}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {91}, shortjournal = {The Astrophys. J.}, title = {Galaxies lighting up: Discovery of seventy new turn-on changing-look active galactic nuclei}, volume = {980}, year = {2025}, }
• (2025). Metallicity and α-abundance for 48 million stars in low-extinction regions in the milky way. ApJ, 980(1), 90. (www)

  @article{ , abstract = {We estimate ([M/H], [ α /M]) for 48 million giants and dwarfs in low-dust extinction regions from the Gaia DR3 XP spectra by using tree-based machine learning models trained on APOGEE DR17 and a metal-poor star sample from Li et al. The root mean square error of our estimation is 0.0890 dex for [M/H] and 0.0436 dex for [ α /M], when we evaluate our models on the test data that are not used in training the models. Because the training data is dominated by giants, our estimation is most reliable for giants. The high-[ α /M] stars and low-[ α /M] stars selected by our ([M/H], [ α /M]) show different kinematical properties for giants and low-temperature dwarfs. We further investigate how our machine learning models extract information on ([M/H], [ α /M]). Intriguingly, we find that our models seem to extract information on [ α /M] from Na D lines (589 nm) and Mg i line (516 nm). This result is understandable given the observed correlation between Na and Mg abundances in the literature. The catalog of ([M/H], [ α /M]) as well as their associated uncertainties is publicly available.}, archive = {J_ApJ}, author = {Kohei Hattori}, doi = {10.3847/1538-4357/ad9686}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {90}, shortjournal = {The Astrophys. J.}, title = {Metallicity and α-abundance for 48 million stars in low-extinction regions in the milky way}, volume = {980}, year = {2025}, }
• (2025). Statistics of the interplanetary magnetic field from 0.1 to 30 au. i. distribution character. ApJ, 980(1), 89. (www)

  @article{ , abstract = {This study investigates the directional and intensity distributions of the interplanetary magnetic field (IMF) across a heliocentric distance range of approximately 0.1–30 au. Measurements from multiple spacecraft reveal that these distributions align closely with the Parker spiral configuration in general. Nevertheless, the deviation from the model is significant and regular. To analyze these deviations, we organized the IMF observations based on the orientation and intensity predicted by the Parker model. The average angular deviation from the Parker spiral increases between 0.1 and 1 au, stabilizing from 1 to 30 au. The magnetic field components perpendicular to the Parker spiral are more likely to lay in the latitudinal and longitudinal directions during the solar maximum and minimum, respectively. The normalized intensity distribution follows a log-normal distribution, with its broadening positively correlated with increasing heliocentric distance. These characteristics cannot be fully attributed to Alfvénic fluctuations or the nonradial component near the potential field source surface. Instead, interactions of flux tubes in the outer heliosphere play a significant role in shaping the IMF. Our results provide a comprehensive assessment of the frequency with which planets encounter non-Parker upstream conditions.}, archive = {J_ApJ}, author = {Jiutong Zhao and Shan Wang and Weijie Sun and Xingyu Zhu and Chuanpeng Hou and Qiugang Zong and Jiansen He and Xuzhi Zhou and Chao Yue and Liu Yang}, doi = {10.3847/1538-4357/ad9b28}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {89}, shortjournal = {The Astrophys. J.}, title = {Statistics of the interplanetary magnetic field from 0.1 to 30 au. i. distribution character}, volume = {980}, year = {2025}, }
• (2025). Study of long-term spectral evolution and X-ray and γ-ray correlation of blazars seen by HAWC. ApJ, 980(1), 88. (www)

  @article{ , abstract = {The HAWC Observatory collected 6 yr of extensive data, providing an ideal platform for long-term monitoring of blazars in the very high energy (VHE) band, without bias toward specific flux states. HAWC continuously monitors blazar activity at TeV energies, focusing on sources with a redshift of z ≤ 0.3, based on the Third Fermi-LAT Catalog of High-Energy sources. We specifically focused our analysis on Mrk 421 and Mrk 501, as they are the brightest blazars observed by the HAWC Observatory. With a data set of 2143 days, this work significantly extends the monitoring previously published, which was based on 511 days of observation. By utilizing HAWC data for the VHE γ -ray emission in the 300 GeV–100 TeV energy range, in conjunction with Swift-XRT data for the 0.3–10 keV X-ray emission, we aim to explore potential correlations between these two bands. For Mrk 501, we found evidence of a long-term correlation. Additionally, we identified a period in the light curve where the flux was very low for more than 2 yr. On the other hand, our analysis of Mrk 421 measured a strong linear correlation for quasi-simultaneous observations collected by HAWC and Swift-XRT. This result is consistent with a linear dependence and a multiple-zone synchrotron self-Compton model to explain the X-ray and γ -ray emission. Finally, as suggested by previous findings, we confirm a harder-when-brighter behavior in the spectral evolution of the flux properties for Mrk 421. These findings contribute to the understanding of blazar emissions and their underlying mechanisms.}, archive = {J_ApJ}, author = {R. Alfaro and C. Alvarez and A. Andrés and J.C. Arteaga-Velázquez and D. Avila Rojas and H.A. Ayala Solares and R. Babu and E. Belmont-Moreno and A. Bernal and K.S. Caballero-Mora and T. Capistrán and A. Carramiñana and F. Carreón and S. Casanova and U. Cotti and J. Cotzomi and S. Coutiño de León and E. De la Fuente and D. Depaoli and N. Di Lalla and R. Diaz Hernandez and B.L. Dingus and M.A. DuVernois and M. Durocher and J.C. Díaz-Vélez and K. Engel and C. Espinoza and K.L. Fan and N. Fraija and S. Fraija and J.A. García-González and F. Garfias and A. Gonzalez Muñoz and M.M. González and J.A. Goodman and S. Groetsch and J.P. Harding and S. Hernández-Cadena and I. Herzog and D. Huang and F. Hueyotl-Zahuantitla and A. Iriarte and V. Joshi and S. Kaufmann and D. Kieda and A. Lara and W.H. Lee and J. Lee and H. León Vargas and J.T. Linnemann and A.L. Longinotti and G. Luis-Raya and K. Malone and O. Martinez and I. Martinez-Castellanos and J. Martínez-Castro and J.A. Matthews and P. Miranda-Romagnoli and J.A. Montes and E. Moreno and M. Mostafá and A. Nayerhoda and L. Nellen and M.U. Nisa and R. Noriega-Papaqui and N. Omodei and M. Osorio and Y. Pérez Araujo and E.G. Pérez-Pérez and C.D. Rho and D. Rosa-González and E. Ruiz-Velasco and H. Salazar and D. Salazar-Gallegos and A. Sandoval and M. Schneider and J. Serna-Franco and A.J. Smith and Y. Son and R.W. Springer and O. Tibolla and K. Tollefson and I. Torres and R. Torres-Escobedo and R. Turner and F. Ureña-Mena and E. Varela and L. Villaseñor and X. Wang and I.J. Watson and K. Whitaker and E. Willox and S. Yun-Cárcamo and H. Zhou and C. de León and (HAWC collaboration) and Abraham D. Falcone and Fredric Hancock}, doi = {10.3847/1538-4357/ad9d3d}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {88}, shortjournal = {The Astrophys. J.}, title = {Study of long-term spectral evolution and X-ray and γ-ray correlation of blazars seen by HAWC}, volume = {980}, year = {2025}, }
• (2025). Magnetic fields in massive star-forming regions (MagMaR). v. the magnetic field at the onset of high-mass star formation. ApJ, 980(1), 87. (www)

  @article{ , abstract = {A complete understanding of the initial conditions of high-mass star formation and what processes determine multiplicity requires the study of the magnetic field in young massive cores. Using Atacama Large Millimeter/submillimeter Array (ALMA) 250 GHz polarization observations (0 \mathop{.}\limits^{^{\prime\prime} } 3 = 1000 au) and ALMA 220 GHz high-angular-resolution observations (0 \mathop{.}\limits^{^{\prime\prime} } 05 = 160 au), we have performed a full energy analysis including the magnetic field at core scales and have assessed what influences the multiplicity inside a massive core previously believed to be in the prestellar phase. With a mass of 31 M ⊙ , the G11.92 MM2 core has a young CS molecular outflow with a dynamical timescale of a few thousand years. At high resolution, the MM2 core fragments into a binary system, with a projected separation of 505 au and a binary mass ratio of 1.14. Using the Davis–Chandrasekhar–Fermi method with an angle dispersion function analysis, we estimate in this core a magnetic field strength of 6.2 mG and a mass-to-magnetic-flux ratio of 18. The MM2 core is strongly subvirialized, with a virial parameter of 0.064, including the magnetic field. The high mass-to-magnetic-flux ratio and low virial parameter indicate that this massive core is very likely undergoing runaway collapse, which is in direct contradiction with the core accretion model. The MM2 core is embedded in a filament that has a velocity gradient consistent with infall. In line with clump-fed scenarios, the core can grow in mass at a rate of 1.9–5.6 × 10 −4 M ⊙ yr −1 . In spite of the magnetic field having only a minor contribution to the total energy budget at core scales (a few thousands of astronomical units), it likely plays a more important role at smaller scales (a few hundreds of astronomical units) by setting the binary properties. Considering energy ratios and a fragmentation criterion at the core scale, the binary system could have been formed by core fragmentation. The binary system properties (projected separation and mass ratio), however, are also consistent with radiation-magnetohydrodynamic simulations with super-Alfvenic or supersonic (or sonic) turbulence that form binaries by disk fragmentation.}, archive = {J_ApJ}, author = {Patricio Sanhueza and Junhao Liu and Kaho Morii and Josep Miquel Girart and Qizhou Zhang and Ian W. Stephens and James M. Jackson and Paulo C. Cortés and Patrick M. Koch and Claudia J. Cyganowski and Piyali Saha and Henrik Beuther and Suinan Zhang and Maria T. Beltrán and Yu Cheng and Fernando A. Olguin and Xing Lu and Spandan Choudhury and Kate Pattle and Manuel Fernández-López and Jihye Hwang and Ji-hyun Kang and Janik Karoly and Adam Ginsburg and A.-Ran Lyo and Kotomi Taniguchi and Wenyu Jiao and Chakali Eswaraiah and Qiu-yi Luo and Jia-Wei Wang and Benoît Commerçon and Shanghuo Li and Fengwei Xu and Huei-Ru Vivien Chen and Luis A. Zapata and Eun Jung Chung and Fumitaka Nakamura and Sandhyarani Panigrahy and Takeshi Sakai}, doi = {10.3847/1538-4357/ad9d40}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {87}, shortjournal = {The Astrophys. J.}, title = {Magnetic fields in massive star-forming regions (MagMaR). v. the magnetic field at the onset of high-mass star formation}, volume = {980}, year = {2025}, }
• (2025). Insights into the properties of type Ibn/Icn supernovae and their progenitor channels through X-ray emission. ApJ, 980(1), 86. (www)

  @article{ , abstract = {Type Ibn/Icn supernovae (SNe Ibn/Icn), which are characterized by narrow helium or carbon lines that originated in hydrogen-poor dense circumstellar medium (CSM), provide new insights into the final evolution of massive stars. While SNe Ibn/Icn are expected to emit strong X-rays through the strong supernova (SN)-CSM interaction, the X-ray emission modeling effort has been limited so far. In the present study, we provide broad-band X-ray light curve (LC) predictions for SNe Ibn/Icn. We find that the soft X-ray LC provides information about the CSM compositions, while the hard X-ray LC is a robust measure of the CSM density, the explosion energy, and the ejecta mass. In addition, considering the evolution of the ionization state in the unshocked CSM, a bright soft X-ray is expected in the first few days since the explosion, which encourages rapid X-ray follow-up observations as a tool to study the nature of SNe Ibn/Icn. Applying our model to the soft X-ray LCs of SNe Ibn 2006jc and 2022ablq, we derive that the CSM potentially contains a larger fraction of carbon and oxygen for SN 2006jc than 2022ablq, highlighting the power of the soft X-ray modeling to address the nature of the CSM. We also discuss detectability and observational strategy, with which the currently operating telescopes such as NuSTAR and Swift can offer an irreplaceable opportunity to explore the nature of these enigmatic rapid transients and their still-unclarified progenitor channel(s).}, archive = {J_ApJ}, author = {Yusuke Inoue and Keiichi Maeda}, doi = {10.3847/1538-4357/ad9de6}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {86}, shortjournal = {The Astrophys. J.}, title = {Insights into the properties of type Ibn/Icn supernovae and their progenitor channels through X-ray emission}, volume = {980}, year = {2025}, }
• (2025). Striking a chord with spectral sirens: Multiple features in the compact binary population correlate with h0. ApJ, 980(1), 85. (www)

  @article{ , abstract = {Spectral siren measurements of the Hubble constant ( H 0 ) rely on correlations between observed detector-frame masses and luminosity distances. Features in the source-frame mass distribution can induce these correlations. It is crucial, then, to understand (i) which features in the source-frame mass distribution are robust against model (re)parameterization, (ii) which features carry the most information about H 0 , and (iii) whether distinct features independently correlate with cosmological parameters. We study these questions using real gravitational-wave observations from the LIGO-Virgo-KAGRA Collaborations' third observing run. Although constraints on H 0 are weak, we find that current data reveals several prominent features in the mass distribution, including peaks in the binary black hole source-frame mass distribution near ∼9 M ⊙ and ∼32 M ⊙ and a roll-off at masses above ∼46 M ⊙. For the first time using real data, we show that all of these features carry cosmological information and that the peak near ∼32 M ⊙ consistently correlates with H 0 most strongly. Introducing model-independent summary statistics, we show that these statistics independently correlate with H 0 , exactly what is required to limit systematics within future spectral siren measurements from the (expected) astrophysical evolution of the mass distribution.}, archive = {J_ApJ}, author = {Utkarsh Mali and Reed Essick}, doi = {10.3847/1538-4357/ad9de7}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {85}, shortjournal = {The Astrophys. J.}, title = {Striking a chord with spectral sirens: Multiple features in the compact binary population correlate with h0}, volume = {980}, year = {2025}, }
• (2025). Assessing the dark matter content of two quasar host galaxies at z ∼ 6 through gas kinematics. ApJ, 980(1), 84. (www)

  @article{ , abstract = {We conduct a study of the gas kinematics of two quasar host galaxies at z ≳ 6 traced by the [C ii ] emission line using the Atacama Large Millimeter/submillimeter Array. By combining deep observations at both low and high resolution, we recover the diffuse emission, resolve its structure, and measure the rotation curves from the inner region of the galaxy to its outskirts using DysmalPy and 3D Barolo . Assuming that both galaxies exhibit disk rotation driven by the gravitational potential of the galaxy, we find that the best-fit disk models have a V rot / σ ≈ 2 and inferred circular velocities out to ∼6–8 kpc scales, well beyond the likely stellar distribution. We then determine the mass profiles of each component (stars, gas, dark matter) with priors on the baryon and dark matter properties. We find relatively large dark matter fractions within their effective radii ( f DM ( R < R e ) = {0.61}_{-0.08}^{+0.08} and {0.53}_{-0.23}^{+0.20} , respectively), which are significantly larger than those extrapolated from lower redshift studies and remain robust under different input parameters verified by Monte Carlo simulations. The large f DM ( R < R e ) corresponds to halo masses of ∼10 12.5 −10 12.8 M ⊙ , thus representative of the most massive halos at these redshifts. Notably, while the masses of these supermassive black holes (SMBHs) are approximately 1 dex higher than the low-redshift relationship with stellar mass, the closer alignment of SMBH and halo masses with a local relationship may indicate that the early formation of these SMBHs is linked to their dark matter halos, providing insights into the coevolution of galaxies and black holes in the early Universe.}, archive = {J_ApJ}, author = {Qinyue Fei and John D. Silverman and Seiji Fujimoto and Ran Wang and Luis C. Ho and Manuela Bischetti and Stefano Carniani and Michele Ginolfi and Gareth Jones and Roberto Maiolino and Wiphu Rujopakarn and N. M. Förster Schreiber and Juan M. Espejo Salcedo and L. L. Lee}, doi = {10.3847/1538-4357/ada145}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {84}, shortjournal = {The Astrophys. J.}, title = {Assessing the dark matter content of two quasar host galaxies at z ∼ 6 through gas kinematics}, volume = {980}, year = {2025}, }
• (2025). Chasing the beginning of reionization in the JWST era. ApJ, 980(1), 83. (www)

  @article{ , abstract = {Recent JWST observations at z > 6 may imply galactic ionizing photon production above prior expectations. Under observationally motivated assumptions about escape fractions, these suggest a z ~ 8–9 end to reionization, in tension with the z < 6 end required by the Ly α forest. In this work, we use radiative transfer simulations to understand what different observations tell us about when reionization ended and when it started. We consider a model that ends too early ( z end ≈ 8) alongside two more realistic scenarios with z end ≈ 5: one starting late ( z ~ 9) and another early ( z ~ 13). We find that the latter requires up to an order-of-magnitude evolution in galaxy ionizing properties at 6 < z < 12, perhaps in tension with measurements of ξ ion by JWST, which indicate little evolution. We study how these models compare to recent measurements of the Ly α forest opacity, mean free path, intergalactic medium thermal history, visibility of z > 8 Ly α emitters, and the patchy kSZ signal from the cosmic microwave background (CMB). We find that neither of the late-ending scenarios is strongly disfavored by any single data set. However, a majority of observables, spanning several distinct types of observations, prefer a late start. Not all probes agree with this conclusion, hinting at a possible lack of concordance arising from deficiencies in observations and/or theoretical modeling. Observations by multiple experiments (including JWST, Roman, and CMB-S4) in the coming years will establish a concordance picture of reionization's beginning or uncover such deficiencies.}, archive = {J_ApJ}, author = {Christopher Cain and Garett Lopez and Anson D’Aloisio and Julian B. Muñoz and Rolf A. Jansen and Rogier A. Windhorst and Nakul Gangolli}, doi = {10.3847/1538-4357/ada152}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {83}, shortjournal = {The Astrophys. J.}, title = {Chasing the beginning of reionization in the JWST era}, volume = {980}, year = {2025}, }
• (2025). Late-time optical and X-ray emission evolution of the oxygen-rich SN 1996cr. ApJ, 980(1), 82. (www)

  @article{ , abstract = {When the ejecta of a supernova (SN) interact with the progenitor star's circumstellar environment, a strong shock is driven back into the ejecta, causing the material to become bright optically and in X-rays. Most notably, as the shock traverses the H-rich envelope, it begins to interact with metal-rich material. Thus, continued monitoring of bright and nearby SNe provides valuable clues about both the progenitor structure and its pre-SN evolution. Here we present late-time, multiepoch optical and Chandra X-ray spectra of the core-collapse SN, SN 1996cr. Magellan IMACS optical spectra taken in 2017 July and 2021 August show a very different spectrum from that seen in 2006 with broad, double-peaked optical emission lines of oxygen, argon, and sulfur with expansion velocities of ±4500 km s −1 . Redshifted emission components are considerably fainter compared to the blueshifted components, presumably due to internal extinction from dust in the SN ejecta. Broad ±2400 km s −1 H α is also seen, which we infer is shocked progenitor pre-SN, mass-loss, H-rich material. Chandra data indicate a slow but steady decline in the overall X-ray luminosity, suggesting that the forward shock has broken through any circumstellar shell or torus, which is inferred from prior deep Chandra ACIS-S/HETG observations. The X-ray properties are consistent with what is expected from a shock breaking out into a lower-density environment. Though originally identified as a Type IIn SN, based upon late-time optical emission-line spectra, we argue that the SN 1996cr progenitor was partially or highly stripped, suggesting a Type IIb/Ib SN.}, archive = {J_ApJ}, author = {Daniel Patnaude and Kathryn E. Weil and Robert A. Fesen and Dan Milisavljevic and Ralph P. Kraft}, doi = {10.3847/1538-4357/ada15b}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {82}, shortjournal = {The Astrophys. J.}, title = {Late-time optical and X-ray emission evolution of the oxygen-rich SN 1996cr}, volume = {980}, year = {2025}, }
• (2025). Fermi unassociated sources in the MeerKAT absorption line survey. ApJ, 980(1), 81. (www)

  @article{ , abstract = {Over 2000 γ -ray sources identified by the Large Area Telescope on NASA's Fermi Gamma-ray Space Telescope are considered unassociated, meaning that they have no known counterparts in any other frequency regime. We have carried out an image-based search for steep spectrum radio sources, with in-band spectral index < −1.4, within the error regions of Fermi unassociated sources using 1–1.4 GHz radio data from the MeerKAT Absorption Line Survey (MALS) data release. The first MALS data release with a median rms noise of 22–25 μ Jy and 735,649 sources is a significant advance over past image-based searches with improvements in sensitivity, resolution, and bandwidth. Steep spectrum candidates were identified using a combination of in-band spectral indices from MALS and existing radio surveys. We developed an optical and infrared source classification scheme in order to distinguish between Galactic pulsars and radio galaxies. In total, we identify nine pulsar candidates toward six Fermi sources that are worthy of follow-up for pulsation searches. We also report 41 steep spectrum radio galaxy candidates that may be of interest in searches for high-redshift radio galaxies. We show that MALS, due to its excellent continuum sensitivity, can detect 80% of the known pulsar population. This exhibits the promise of identifying exotic pulsar candidates with future image-based surveys with the Square Kilometre Array and its precursors.}, archive = {J_ApJ}, author = {Morgan Himes and Preshanth Jagannathan and Dale A. Frail and Frank Schinzel and Neeraj Gupta and S. A. Balashev and F. Combes and P. P. Deka and H.-R. Klöckner and E. Momjian and J. D. Wagenveld}, doi = {10.3847/1538-4357/ada1cf}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {81}, shortjournal = {The Astrophys. J.}, title = {Fermi unassociated sources in the MeerKAT absorption line survey}, volume = {980}, year = {2025}, }
• (2025). Associations between scattering screens and interstellar medium filaments. ApJ, 980(1), 80. (www)

  @article{ , abstract = {Pulsar scintillation can be used to measure small-scale structure in the Galaxy, but little is known about the specific interstellar medium (ISM) features that cause scintillation. We searched for ISM counterparts to all scintillation screens for which absolute distances and scattering orientations have been measured—a sample of 12 pulsars and 22 screens. For one pulsar, PSR J0737–3039A, we reanalyze its scintillation screen and find evidence for a highly anisotropic screen. Comparisons with tracers of ionized media did not find any new associations. Instead, for seven of the pulsars analyzed, aligned H i filaments are seen for at least one of their screens, for a total of 12 out of 22 screens. This result seems unlikely to be due to chance: Comparing with random trials, we estimate a likelihood of finding 12 or more screens with aligned emission by chance of only 0.004%. Estimating the significance of the amount of aligned emission (in standard deviations over the mean), the probability of finding as much observed aligned emission by chance is larger, at 1.7%, but still indicative of a real correlation. Since H i filaments are preferentially associated with cold neutral gas, and thus unlikely to cause scintillation, this may indicate that both the filaments and the screens are aligned preferentially by the same mechanisms, such as magnetic fields or shocks.}, archive = {J_ApJ}, author = {Ashley M. Stock and Marten H. van Kerkwijk}, doi = {10.3847/1538-4357/ada1d8}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {80}, shortjournal = {The Astrophys. J.}, title = {Associations between scattering screens and interstellar medium filaments}, volume = {980}, year = {2025}, }
• (2025). MAGICS. II. seed black holes stripped of their surrounding stars do not sink. ApJ, 980(1), 79. (www)

  @article{ , abstract = {Massive black hole (MBH) seed mergers are expected to be among the loudest sources of gravitational waves detected by the Laser Interferometer Space Antenna, providing a unique window into the birth and early growth of MBHs. We present the MAGICS-II simulation suite, which consists of six galaxy mergers that result in MBH seed mergers identified in the cosmological simulation ASTRID. With the enhanced resolution (mass resolution: 500 M ⊙ ; softening length: 5 pc), improved subgrid models for the MBH dynamics and accretion, and the accurate regularized gravity integrator included in KETJU, we trace MBH seed dynamics down to 0.1 pc. After evolving all the systems for  ≈1.2 Gyr in three stages (MAGICS-2000, MAGICS-500, and MAGICS-K), we find in four of the six systems that the MBHs stall at separations Δ r ≳ 200 pc. Only in two systems, the MBHs manage to sink further, and only in one of them a bound binary forms. In the sinking systems, the MBH retains a population of bound stars. The final separation between the MBH is related to the surrounding unstripped stellar (and/or dark matter) mass: if more than 90% of the surrounding stellar system is stripped away, the MBHs stall. Besides the unstripped stars from the original host galaxy, we find that newly formed stars bound to the MBH significantly contribute to its sinking. Resolving the stellar system around MBH seeds, and its induced tidal interactions and dynamical friction is key for accurately capturing MBH dynamics. For this, high-resolution simulations are required. In a companion paper (MAGICS-III), we resimulate the central regions of these systems with an increased resolution to model directly the effects of actual star clusters around MBHs.}, archive = {J_ApJ}, author = {Yihao Zhou and Diptajyoti Mukherjee and Nianyi Chen and Tiziana Di Matteo and Peter H. Johansson and Antti Rantala and Christian Partmann and Ugo Niccolò Di Carlo and Simeon Bird and Yueying Ni}, doi = {10.3847/1538-4357/ada283}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {79}, shortjournal = {The Astrophys. J.}, title = {MAGICS. II. seed black holes stripped of their surrounding stars do not sink}, volume = {980}, year = {2025}, }
• (2025). Magnetic field strengths in the vicinity of sgr a* via 18 cm zeeman observations. ApJ, 980(1), 78. (www)

  @article{ , abstract = {Very Large Array (VLA) observations of 18 cm OH absorption lines were used to determine the strength of the line-of-sight magnetic field in the Galactic center region. This study is an extension of the VLA OH Zeeman observations of Killeen et al. with fourfold the on-source integration time and twice the sensitivity to the Zeeman effect. The new data fail to confirm the 7 σ Zeeman detections of 2 mG fields reported in the earlier work. Also, we cannot reproduce these reported detections from our own analysis of archival data of the earlier work. We find no certain detections of the OH Zeeman effect in the Galactic center region. Our results suggest magnetic fields of no more than about a milligauss in the sampled regions.}, archive = {J_ApJ}, author = {K. L. Thompson and T. H. Troland and R. L. Plante}, doi = {10.3847/1538-4357/ada292}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {78}, shortjournal = {The Astrophys. J.}, title = {Magnetic field strengths in the vicinity of sgr a* via 18 cm zeeman observations}, volume = {980}, year = {2025}, }
• (2025). Uncovering deterministic behavior of black hole IGR j17091–3624: A twin of GRS 1915+105. ApJ, 980(1), 77. (www)

  @article{ , abstract = {Understanding the nonlinear properties in accreting systems, particularly for black holes, from observation is illuminating as they are expected to be general relativistic magnetohydrodynamic flows that are nonlinear. Two commonly used features associated with nonlinear systems are chaos, which is deterministic, and randomness, which is stochastic. The differentiation between chaotic and stochastic systems is often considered to quantify the nonlinear properties of an astrophysical system. Particular emphasis is given to the fact that data are often noise contaminated and finite. We examine the dual nature of the black hole X-ray binary IGR J17091–3624, whose behavior has been closely studied in parallel to GRS 1915+105. Certain similarities in the temporal classes of these two objects have been explored in the literature. However, this has not been the case with their nonlinear dynamics: GRS 1915+105 shows signs of both determinism and stochasticity, while IGR J17091–3624 was found to be predominantly stochastic. Here, we confront the inherent challenge of noise contamination faced by previous studies, particularly Poisson noise, which adversely impacts the reliability of nonlinear results. We employ several denoising techniques to mitigate noise effects, and employ methods like principal component analysis, singular value decomposition, and correlation integrals to isolate the deterministic signatures. We find signs of determinism in IGR J17091–3624, thus supporting the hypothesis of it being similar to GRS 1915+105, even as a dynamical system. Our findings not only shed light on the complex nature of IGR J17091–3624 but also pave the way for future research employing noise-reduction techniques to analyze nonlinearity in observed dynamical systems.}, archive = {J_ApJ}, author = {Anindya Guria and Banibrata Mukhopadhyay}, doi = {10.3847/1538-4357/ada296}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {77}, shortjournal = {The Astrophys. J.}, title = {Uncovering deterministic behavior of black hole IGR j17091–3624: A twin of GRS 1915+105}, volume = {980}, year = {2025}, }
• (2025). Tidal reconstruction of neutron star mergers from their late inspiral. ApJ, 980(1), 76. (www)

  @article{ , abstract = {We investigate the measurement correlation between the effective spin and the effective tidal deformability in gravitational-wave signals from binary neutron star mergers. To efficiently measure the effective tidal deformability parameter, we exploit the fact that the tidal effects in a binary system are prominent when the components are closer, during the late inspiral. Thus, we indicate a computationally efficient strategy of extracting the tidal information compressed within the seconds before the merger. We report our observations for GW170817 and explore the suitability of our approach for the upcoming observation scenarios of the current and future ground-based observatories. Fast and accurate measurements of the tidal deformability parameters can be used to inform astronomers when prioritizing the electromagnetic follow-up efforts for such sources.}, archive = {J_ApJ}, author = {Souradeep Pal and Rajesh Kumble Nayak}, doi = {10.3847/1538-4357/ada38e}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {76}, shortjournal = {The Astrophys. J.}, title = {Tidal reconstruction of neutron star mergers from their late inspiral}, volume = {980}, year = {2025}, }
• (2025). Spatial and temporal distribution of nanoflare heating during active region evolution. ApJ, 980(1), 75. (www)

  @article{ , abstract = {Nanoflares are believed to be key contributors to heating solar nonflaring active regions, though their individual detection remains challenging. This study uses a data-driven field-aligned hydrodynamic model to examine nanoflare properties throughout the lifecycle of active region (AR) 12758. We simulate coronal loop emissions, where each loop is heated by random nanoflares depending on the loop parameters derived from photospheric magnetograms observed by the Solar Dynamics Observatory/Helioseismic and Magnetic Imager. Simulated X-ray flux and temperature can reproduce the temporal variations observed by the Chandrayaan-2/Solar X-ray Monitor. Our findings show that high-frequency nanoflares contribute to cool emissions across the AR, while low- and intermediate-frequency primarily contribute to hot emissions. During the emerging phase, energy deposition is dominated by low-frequency events. Post-emergence, energy is deposited by both low- and intermediate-frequency nanoflares, while as the AR ages, the contribution from intermediate- and high-frequency nanoflares increases. The spatial distribution of heating frequencies across the AR reveals a clear pattern: the core of the active region spends most of its time in a low-frequency heating state, the periphery is dominated by high-frequency heating, and the region between the core and periphery experiences intermediate-frequency heating.}, archive = {J_ApJ}, author = {Biswajit Mondal and James A. Klimchuk and Amy R. Winebarger and P. S. Athiray and Jiayi Liu}, doi = {10.3847/1538-4357/ada3d6}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {75}, shortjournal = {The Astrophys. J.}, title = {Spatial and temporal distribution of nanoflare heating during active region evolution}, volume = {980}, year = {2025}, }
• (2025). The lyman continuum escape fraction of star-forming galaxies at 2.4 ≲ z ≲ 3.0 from UVCANDELS. ApJ, 980(1), 74. (www)

  @article{ , abstract = {The UltraViolet Imaging of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey Fields (UVCANDELS) survey is a Hubble Space Telescope (HST) Cycle-26 Treasury Program, allocated in total 164 orbits of primary Wide-Field Camera 3 Ultraviolet and VISible light F275W imaging with coordinated parallel Advanced Camera for Surveys F435W imaging, on four of the five premier extragalactic survey fields: GOODS-N, GOODS-S, EGS, and COSMOS. We introduce this survey by presenting a comprehensive analysis of the absolute escape fraction ( {f}_{{\rm{esc}}}^{{\rm{abs}}} ) of Lyman continuum radiation through stacking the UV images of a population of star-forming galaxies with secure redshifts at 2.4 ≤ z ≤ 3.0. Our stacking benefits from the catalogs of high-quality spectroscopic redshifts compiled from archival ground-based data and HST slitless spectroscopy, carefully vetted by dedicated visual inspection efforts. We develop a robust stacking method to apply to 10 samples of in total 56 galaxies, and perform detailed Monte Carlo simulations of the intergalactic medium (IGM) attenuation, to take into account the sample variance of the mean IGM transmission when measuring {f}_{{\rm{esc}}}^{{\rm{abs}}} . The full stack at z ≈ 2.44 from 28 galaxies places a stringent 1 σ upper limit of {f}_{{\rm{esc}}}^{{\rm{abs}}}\lesssim 5 \% , whereas the full stack at z ≈ 2.72 of an equal number of galaxies gives an upper limit of {f}_{{\rm{esc}}}^{{\rm{abs}}}\lesssim 26 \% at 1 σ confidence level. These new F275W and F435W imaging mosaics from UVCANDELS have been made publicly available on the Barbara A. Mikulski Archive for Space Telescopes.}, archive = {J_ApJ}, author = {Xin Wang and Harry I. Teplitz and Brent M. Smith and Rogier A. Windhorst and Marc Rafelski and Vihang Mehta and Anahita Alavi and Zhiyuan Ji and Gabriel Brammer and James Colbert and Norman Grogin and Nimish P. Hathi and Anton M. Koekemoer and Laura Prichard and Claudia Scarlata and Ben Sunnquist and Pablo Arrabal Haro and Christopher Conselice and Eric Gawiser and Yicheng Guo and Matthew Hayes and Rolf A. Jansen and Ray A. Lucas and Robert O’Connell and Brant Robertson and Michael Rutkowski and Brian Siana and Eros Vanzella and Teresa Ashcraft and Micaela Bagley and Ivano Baronchelli and Guillermo Barro and Alex Blanche and Adam Broussard and Timothy Carleton and Nima Chartab and Yingjie Cheng and Alex Codoreanu and Seth Cohen and Y. Sophia Dai and Behnam Darvish and Romeel Davé and Laura DeGroot and Duilia De Mello and Mark Dickinson and Najmeh Emami and Henry Ferguson and Leonardo Ferreira and Keely Finkelstein and Steven Finkelstein and Jonathan P. Gardner and Timothy Gburek and Mauro Giavalisco and Andrea Grazian and Caryl Gronwall and Shoubaneh Hemmati and Justin Howell and Kartheik Iyer and Sugata Kaviraj and Peter Kurczynski and Ilin Lazar and John MacKenty and Kameswara Bharadwaj Mantha and Alec Martin and Garreth Martin and Tyler McCabe and Bahram Mobasher and Kalina Nedkova and Charlotte Olsen and Lillian Otteson and Swara Ravindranath and Caleb Redshaw and Zahra Sattari and Emmaris Soto and L. Y. Aaron Yung and Bonnabelle Zabelle and the UVCANDELS team}, doi = {10.3847/1538-4357/ada4ab}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {74}, shortjournal = {The Astrophys. J.}, title = {The lyman continuum escape fraction of star-forming galaxies at 2.4 ≲ z ≲ 3.0 from UVCANDELS}, volume = {980}, year = {2025}, }
• (2025). Unraveling the kinematic and morphological evolution of the small magellanic cloud. ApJ, 980(1), 73. (www)

  @article{ , abstract = {We model the kinematics of the Small Magellanic Cloud (SMC) by analyzing the proper motions (PMs) from Gaia DR3 of nine different stellar populations, including young main-sequence (MS) stars (<2 Gyr), red giant branch stars, red clump stars, red giants with line-of-sight velocities, and three groups of star clusters. This analysis is carried out using a robust Markov Chain Monte Carlo method, to derive up to seven kinematic parameters. We trace the evolution from a nonrotating flattened elliptical system, as mapped by the old population, to a rotating highly stretched disk structure, as denoted by the young MS stars and clusters (<400 Myr). We estimate that the inclination i (∼58°–82°) decreases and the position angle Θ (∼180°–240°) increases with age. We estimate an asymptotic velocity of ∼49–89 km s −1 with a scale radius of ∼6–9 kpc for the young MS populations, with velocity dispersion of ∼11 km s −1 , suggesting a rotation-supported disk structure. Our models estimate a line-of-sight extension of ∼30 kpc, in agreement with observations. We identify four regions of the SMC showing anomalies in the residual PM: the East Anomaly, the Southeast Anomaly (SEA), the South Anomaly, and the West Anomaly. The SEA appears like an infalling feature and is identified for the first time. The tidal imprints observed in the residual PM of the SMC suggest that its evolution is considerably shaped by the recent interaction with the Large Magellanic Cloud.}, archive = {J_ApJ}, author = {S. R. Dhanush and A. Subramaniam and S. Subramanian}, doi = {10.3847/1538-4357/ada55f}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {73}, shortjournal = {The Astrophys. J.}, title = {Unraveling the kinematic and morphological evolution of the small magellanic cloud}, volume = {980}, year = {2025}, }
• (2025). The effects of active galactic nuclei feedback on the lyα forest flux power spectrum. ApJ, 980(1), 72. (www)

  @article{ , abstract = {We study the effects of active galactic nuclei (AGN) feedback on the Ly α forest 1D flux power spectrum (P1D). Using the Simba cosmological-hydrodynamic simulations, we examine the impact that adding different AGN feedback modes has on the predicted P1D. We find that, for Simba , the impact of AGN feedback is most dramatic at lower redshifts ( z < 1) and that AGN jet feedback plays the most significant role in altering the P1D. The effects of AGN feedback can be seen across a large range of wavenumbers (1.5 × 10 −3 < k < 10 −1 s km −1 ) changing the ionization state of hydrogen in the IGM through heating. AGN feedback can also alter the thermal evolution of the IGM and thermally broaden individual Ly α absorbers. For the Simba model, these effects become observable at z ≲ 1.0. At higher redshifts ( z > 2.0), AGN feedback has a 2% effect on the P1D for k < 5 × 10 −2 s km −1 and an 8% effect for k > 5 × 10 −2 s km −1 . We show that the small-scale effect is reduced when normalizing the simulation to the observed mean flux. On large scales, the effect of AGN feedback appears via a change in the IGM temperature and is thus unlikely to bias cosmological parameters. The strong AGN jets in the Simba simulation can reproduce the z > 2 Ly α forest. We stress that analyses comparing different AGN feedback models to future higher precision data will be necessary to determine the full extent of this effect.}, archive = {J_ApJ}, author = {Megan Taylor Tillman and Blakesley Burkhart and Stephanie Tonnesen and Simeon Bird and Greg L. Bryan}, doi = {10.3847/1538-4357/ada5f7}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {72}, shortjournal = {The Astrophys. J.}, title = {The effects of active galactic nuclei feedback on the lyα forest flux power spectrum}, volume = {980}, year = {2025}, }
• (2025). GD-1 stellar stream and cocoon in the DESI early data release. ApJ, 980(1), 71. (www)

  @article{ , abstract = {We present  ∼115 new spectroscopically identified members of the GD-1 tidal stream observed with the 5000-fiber Dark Energy Spectroscopic Instrument (DESI). We confirm the existence of a "cocoon," which is a broad (FWHM ∼ 2 \mathop{.}\limits^{\unicode{x000b0}} 932 ∼ 460 pc) and kinematically hot (velocity dispersion, σ ∼ 5–8 km s −1 ) component that surrounds a narrower (FWHM ∼ 0 \mathop{.}\limits^{\unicode{x000b0}} 353 ∼ 55 pc) and colder [( σ = 3.09 ± 0.76 km s −1 )] thin stream component (based on a median per star velocity precision of 2.7 km s −1 ). The cocoon extends over at least a 30 ∘ segment of the stream observed by DESI. The thin and cocoon components have similar mean values of [Fe/H]: −2.54 ± 0.04 dex and −2.47 ± 0.06 dex, suggestive of a common origin. The data are consistent with the following scenarios for the origin of the cocoon. The progenitor of the GD-1 stream was an accreted globular cluster (GC) and: (a) the cocoon was produced by pre-accretion tidal stripping of the GC while it was still inside its parent dwarf galaxy; (b) the cocoon comprises debris from the parent dwarf galaxy; (c) an initially thin GC tidal stream was heated by impacts from dark subhalos in the Milky Way; (d) an initially thin GC stream was heated by a massive Sagittarius dwarf galaxy; or a combination of some of these. Future DESI spectroscopy and detailed modeling may enable us to distinguish between these possible origins.}, archive = {J_ApJ}, author = {M. Valluri and P. Fagrelius and S. E. Koposov and T. S. Li and Oleg Y. Gnedin and E. F. Bell and R. G. Carlberg and A. P. Cooper and J. Aguilar and S. Ahlen and C. Allende Prieto and V. Belokurov and L. Beraldo e Silva and D. Brooks and A. Byström and T. Claybaugh and K. Dawson and A. Dey and P. Doel and J. E. Forero-Romero and E. Gaztañaga and S. Gontcho A Gontcho and J. Han and K. Honscheid and T. Kisner and A. Kremin and A. Lambert and M. Landriau and L. Le Guillou and M. E. Levi and A. de la Macorra and M. Manera and P. Martini and G. E. Medina and A. Meisner and R. Miquel and J. Moustakas and A. D. Myers and J. Najita and C. Poppett and F. Prada and M. Rezaie and G. Rossi and A. H. Riley and E. Sanchez and D. Schlegel and M. Schubnell and D. Sprayberry and G. Tarlé and G. Thomas and B. A. Weaver and R. H. Wechsler and R. Zhou and H. Zou}, doi = {10.3847/1538-4357/ada690}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {71}, shortjournal = {The Astrophys. J.}, title = {GD-1 stellar stream and cocoon in the DESI early data release}, volume = {980}, year = {2025}, }
• (2025). Differentiating the acceleration mechanisms in the slow and alfvénic slow solar wind. ApJ, 980(1), 70. (www)

  @article{ , abstract = {In the corona, plasma is accelerated to hundreds of kilometers per second and heated to temperatures hundreds of times hotter than the Sun's surface before it escapes to form the solar wind. Decades of space-based experiments have shown that the energization process does not stop after it escapes. Instead, the solar wind continues to accelerate, and it cools far more slowly than a freely expanding adiabatic gas. Recent work suggests that fast solar wind requires additional momentum beyond what can be provided by the observed thermal pressure gradients alone, whereas it is sufficient for the slowest wind. The additional acceleration for fast wind can be provided through an Alfvén wave pressure gradient. Beyond this fast/slow categorization, however, a subset of slow solar wind exhibits high Alfvénicity that suggests that Alfvén waves could play a larger role in its acceleration compared to conventional slow wind outflows. Through a well-timed conjunction between Solar Orbiter and Parker Solar Probe (PSP), we trace the energetics of slow wind to compare with a neighboring Alfvénic slow solar wind stream. An analysis that integrates remote and heliospheric properties and modeling of the two distinct solar wind streams finds that Alfvénic slow solar wind behaves like fast wind, where a wave pressure gradient is required to reconcile its full acceleration, while non-Alfvénic slow wind can be driven by its nonadiabatic electron and proton thermal pressure gradients. Derived coronal conditions of the source region indicate good model compatibility, but extended coronal observations are required to effectively trace solar wind energetics below PSP's orbit.}, archive = {J_ApJ}, author = {Yeimy J. Rivera and Samuel T. Badman and J. L. Verniero and Tania Varesano and Michael L. Stevens and Julia E. Stawarz and Katharine K. Reeves and Jim M. Raines and John C. Raymond and Christopher J. Owen and Stefano A. Livi and Susan T. Lepri and Enrico Landi and Jasper. S. Halekas and Tamar Ervin and Ryan M. Dewey and Rossana De Marco and Raffaella D’Amicis and Jean-Baptiste Dakeyo and Stuart D. Bale and B. L. Alterman}, doi = {10.3847/1538-4357/ada699}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {70}, shortjournal = {The Astrophys. J.}, title = {Differentiating the acceleration mechanisms in the slow and alfvénic slow solar wind}, volume = {980}, year = {2025}, }
• (2025). Deciphering gas dynamics and star formation in a z = 1.1 main-sequence spiral galaxy with ALMA and JWST. ApJ, 980(1), 69. (www)

  @article{ , abstract = {We present a joint analysis of high-resolution CO(2–1) and Paschen- α (Pa α ) emission lines to trace gas dynamics and spatially resolved star formation in ASPECS-LP.3 mm.06, a z = 1.1 main-sequence galaxy. Utilizing data from the Atacama Large Millimeter/submillimeter Array and JWST NIRCam wide field slitless spectroscopy, we explore both ionized gas and molecular gas within this galaxy. With a substantial molecular gas fraction ( f mol = 0.44  ±  0.02), ASPECS-LP.3 mm.06 remains on the star-forming main sequence and adheres to the Kennicutt–Schmidt relation, indicating typical gas-to-star conversion efficiency. Our analysis reveals extended structures across multiple wavelengths, suggesting regulated star formation within a stable disk. The spatially resolved star formation efficiency and kinematic analysis indicate that ASPECS-LP.3mm.06 features a smooth mass assembly process across the bulge and disk. Additionally, the galaxy exhibits modest dust extinction ( A V = 0.8), potentially linked to self-regulation during bulge formation. These findings position ASPECS-LP.3mm.06 as a prototypical galaxy, offering valuable insights into the mechanisms governing normal disk galaxy growth at z ∼ 1.}, archive = {J_ApJ}, author = {Zhaoran Liu and Tadayuki Kodama and Takahiro Morishita and Kianhong Lee and Fengwu Sun and Mariko Kubo and Zheng Cai and Yunjing Wu and Zihao Li}, doi = {10.3847/1538-4357/ada937}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {69}, shortjournal = {The Astrophys. J.}, title = {Deciphering gas dynamics and star formation in a z = 1.1 main-sequence spiral galaxy with ALMA and JWST}, volume = {980}, year = {2025}, }
• (2025). Neutrino-dominated relativistic viscous accretion flows around rotating black holes with shocks. ApJ, 980(1), 68. (www)

  @article{ , abstract = {We investigate the relativistic, viscous, advective neutrino-dominated accretion flows (NDAFs) around rotating stellar-mass black holes, incorporating neutrino cooling. By adopting an effective potential to describe the spacetime geometry around the rotating black holes, we self-consistently solve the governing NDAF equations to obtain global transonic accretion solutions. Our findings indicate that, depending on the model parameters, namely, energy ( ε ), angular momentum ( λ ), accretion rate ( \dot{m} ), viscosity ( α ), and black hole spin ( a k ), NDAFs may harbor standing shocks where the Rankine–Hugoniot shock conditions are satisfied. Utilizing these shock-induced NDAF solutions, we compute the neutrino luminosity ( L ν ) and neutrino annihilation luminosity ( {L}_{\nu \bar{\nu }} ) across a wide range of model parameters. We further calculate maximum neutrino luminosity ( {L}_{\nu }^{{\rm{\max }}} ) and neutrino annihilation luminosity ( {L}_{\nu \bar{\nu }}^{{\rm{\max }}} ), resulting in {L}_{\nu }^{{\rm{\max }}}\sim 1{0}^{51-53} erg s −1 (10 48−51 erg s −1 ) and {L}_{\nu \bar{\nu }}^{{\rm{\max }}}\sim 1{0}^{48-52} erg s −1 (10 42−49 erg s −1 ) for a k = 0.99 (0.0). These findings suggest that shocked NDAF solutions are potentially promising to explain the energy output of gamma-ray bursts (GRBs). We employ our NDAF model formalism to elucidate {L}_{\nu \bar{\nu }}^{{\rm{obs}}} for five GRBs with known redshifts and estimate their accretion rate ( \dot{m} ) based on the spin ( a k ) of the central source of the GRBs studied here.}, archive = {J_ApJ}, author = {Amit Kumar and Sayan Chakrabarti and Santabrata Das}, doi = {10.3847/1538-4357/adabc8}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {68}, shortjournal = {The Astrophys. J.}, title = {Neutrino-dominated relativistic viscous accretion flows around rotating black holes with shocks}, volume = {980}, year = {2025}, }
• (2025). A unifying polarization formalism for electric and magnetic multipole interactions. ApJ, 980(1), 67. (www)

  @article{ , abstract = {We extend the spherical tensorial formalism for polarization to the treatment of electric and magnetic multipole transitions of any order. We rely on the spherical-wave expansion to derive the tensor form of the operator describing the interaction of the atomic system with a polarized radiation field, which naturally leads to the introduction of spherical tensors describing the polarization properties of the interacting field. As a direct application, the formalism is used to model the radiation anisotropy affecting the scattering of radiation in an electric quadrupole transition and the associated Hanle effect in the presence of a magnetic field.}, archive = {J_ApJ}, author = {R. Casini and R. Manso Sainz and A. López Ariste and N. Kaikati}, doi = {10.3847/1538-4357/ad7677}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {67}, shortjournal = {The Astrophys. J.}, title = {A unifying polarization formalism for electric and magnetic multipole interactions}, volume = {980}, year = {2025}, }
• (2025). TransformerPayne: Enhancing spectral emulation accuracy and data efficiency by capturing long-range correlations. ApJ, 980(1), 66. (www)

  @article{ , abstract = {Stellar spectra emulators often rely on large grids and tend to reach a plateau in emulation accuracy, leading to significant systematic errors when inferring stellar properties. Our study explores the use of Transformer models to capture long-range information in spectra, comparing their performance to the Payne emulator (a fully connected multilayer perceptron), an expanded version of The Payne, and a convolutional-based emulator. We tested these models on synthetic spectral grids, evaluating their performance by analyzing emulation residuals and assessing the quality of spectral parameter inference. The newly introduced TransformerPayne emulator outperformed all other tested models, achieving a mean absolute error (MAE) of approximately 0.15% when trained on the full grid. The most significant improvements were observed in grids containing between 1000 and 10,000 spectra, with TransformerPayne showing 2–5 times better performance than the scaled-up version of The Payne. Additionally, TransformerPayne demonstrated superior fine-tuning capabilities, allowing for pretraining on one spectral model grid before transferring to another. This fine-tuning approach enabled up to a 10-fold reduction in training grid size compared to models trained from scratch. Analysis of TransformerPayne's attention maps revealed that they encode interpretable features common across many spectral lines of chosen elements. While scaling up The Payne to a larger network reduced its MAE from 1.2% to 0.3% when trained on the full data set, TransformerPayne consistently achieved the lowest MAE across all tests. The inductive biases of the TransformerPayne emulator enhance accuracy, data efficiency, and interpretability for spectral emulation compared to existing methods.}, archive = {J_ApJ}, author = {Tomasz Różański and Yuan-Sen Ting and Maja Jabłońska}, doi = {10.3847/1538-4357/ad9b99}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {66}, shortjournal = {The Astrophys. J.}, title = {TransformerPayne: Enhancing spectral emulation accuracy and data efficiency by capturing long-range correlations}, volume = {980}, year = {2025}, }
• (2025). Determination of the analytical solutions of the radio emission geometry and polar cap structure of pulsars having perturbed dipole. ApJ, 980(1), 65. (www)

  @article{ , abstract = {We model an analytical solution to generate the shape of the polar cap structure and discuss the geometrical distortion due to the presence of both longitudinal plasma current flow across the polar cap regime, i.e., polar cap current perturbation, and pulsar rotation, i.e., rotational perturbation. An analytical solution to the parameter space associated with the radio emission geometrical coordinate is produced by using the first- and second-order power series expansion method for the rotationally perturbed dipole case. In general, polar caps show a quasi-elliptical shape, but in the presence of higher-order plasma current our results show that they can be converted into an elliptical structure with a monotonically reduced dimension. Our results show that the rotational effect also leads to a contraction of the dimensions of the polar cap for a given range of the obliquity parameters. We have found that the last open field line constant, as a fraction of the light cylinder radius, decreases in the presence of nonzero plasma current discharge. We also demonstrate that under certain conditions introducing a higher-order plasma current (e.g., with a scale factor ζ p = J / J GJ close to 1 in the closed field line region) can lead to a structure resembling a cosmic-combed magnetosphere.}, archive = {J_ApJ}, author = {Tridib Roy and Mageshwaran Tamilan and Ramkrishna Das}, doi = {10.3847/1538-4357/ad9f2a}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {65}, shortjournal = {The Astrophys. J.}, title = {Determination of the analytical solutions of the radio emission geometry and polar cap structure of pulsars having perturbed dipole}, volume = {980}, year = {2025}, }
• (2025). Mapping the active galactic nucleus effects on the stellar and gas properties of NGC 5806. ApJ, 980(1), 64. (www)

  @article{ , abstract = {It is commonly accepted that active galactic nuclei (AGNs) have a strong impact upon the evolution of their host galaxies, but the processes by which they do so are not fully understood. We aim to further the understanding of AGN feeding and feedback by examining an active galaxy using spatially resolved spectroscopy. We analyze integral field spectroscopy of the active galaxy NGC 5806, obtained using the Very Large Telescope Multi-Unit Spectroscopic Explorer. We map the dynamics of gas and stars, as well as gas optical emission line fluxes throughout the central 8 × 8 kpc 2 of the galaxy. We use emission line ratios to map gas metallicity and identify regions of gas excitation dominated by AGN/shocks or star formation. We also determine the average stellar population age and metallicity, and model the rotation and dynamics of the galaxy. We find that NGC 5806 has a star-forming circumnuclear ring, with a projected radius of ~400 pc. The dynamics of this galaxy are driven by a large-scale bar, which transports gas from the spiral arm to the central ring and potentially fuels the AGN. We also observe AGN-dominated gas excitation up to 3.3 kpc away from the center of the galaxy, showing the extended AGN effect on the gas in the central regions of the galaxy.}, archive = {J_ApJ}, author = {Sophie L. Robbins and Sandra I. Raimundo and Matthew A. Malkan}, doi = {10.3847/1538-4357/ada294}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {64}, shortjournal = {The Astrophys. J.}, title = {Mapping the active galactic nucleus effects on the stellar and gas properties of NGC 5806}, volume = {980}, year = {2025}, }
• (2025). Progenitor diversity in the accreted stellar halos of milky way–like galaxies. ApJ, 980(1), 63. (www)

  @article{ , abstract = {Ongoing large stellar spectroscopic surveys of the Milky Way seek to reconstruct the major events in the assembly history of the Galaxy. Chemical and kinematic observations can be used to separate the contributions of different progenitor galaxies to the present-day stellar halo. Here, we compute the number of progenitors that contribute to the accreted stellar halos of simulated Milky Way–like galaxies as a function of radius (the radial diversity) in three suites of models: Bullock & Johnston, Aquarius, and Auriga. We show that there are significant differences between the predictions of these three models, beyond the halo-to-halo scatter expected in ΛCDM. Predictions of diversity from numerical simulations are sensitive to model-dependent assumptions regarding the efficiency of star formation in dwarf galaxies. We compare, at face value, to current constraints on the radial diversity of the Milky Way's accreted halo. These constraints imply that the halo of our Galaxy is dominated by ∼2 progenitors in the range 8–45 kpc, in contrast to averages of 7 progenitors in the Bullock & Johnston models, 3.5 in Aquarius, and 4.2 in Auriga over the same region. We additionally find that the models with radial diversity most similar to that of the Milky Way are predominantly those with ongoing merger events. The Milky Way therefore appears unusual in having an accreted stellar halo dominated by a small number of progenitors accreted at very early times.}, archive = {J_ApJ}, author = {Sy-Yun Pu and Andrew P. Cooper and Robert J. J. Grand and Facundo A. Gómez and Antonela Monachesi}, doi = {10.3847/1538-4357/ada382}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {63}, shortjournal = {The Astrophys. J.}, title = {Progenitor diversity in the accreted stellar halos of milky way–like galaxies}, volume = {980}, year = {2025}, }
• (2025). AEOS: Transport of metals from minihalos following population III stellar feedback. ApJ, 980(1), 62. (www)

  @article{ , abstract = {We investigate how stellar feedback from the first stars (Population III) distributes metals through the interstellar and intergalactic medium using the star-by-star cosmological hydrodynamics simulation, A eos . We find that energy injected from the supernovae (SNe) of the first stars is enough to expel a majority of gas and injected metals beyond the virial radius of halos with mass M dm ≲ 10 7 M ⊙ , regardless of the number of SNe. This prevents self-enrichment and results in a nonmonotonic increase in metallicity at early times. Most minihalos ( M dm ≳ 10 5 M ⊙ ) do not retain significant fractions of the yields produced within their virial radii until they have grown to halo masses of M dm ≳ 10 7 M ⊙ . The loss of metals to regions well beyond the virial radius delays the onset of enriched star formation and extends the period that Population III star formation can persist. We also explore the contributions of different nucleosynthetic channels to 10 individual elements. On the timescale of the simulation (lowest redshift z = 14.3), enrichment is dominated by core-collapse supernovae for all elements, but with a significant contribution from asymptotic giant branch winds to the s -process elements, which are normally thought to only be important at late times. In this work, we establish important mechanisms for early chemical enrichment, which allows us to apply A eos in later epochs to trace the evolution of enrichment during the complete transition from Population III to Population II stars.}, archive = {J_ApJ}, author = {Jennifer Mead and Kaley Brauer and Greg L. Bryan and Mordecai-Mark Mac Low and Alexander P. Ji and John H. Wise and Andrew Emerick and Eric P. Andersson and Anna Frebel and Benoit Côté}, doi = {10.3847/1538-4357/ada3c1}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {62}, shortjournal = {The Astrophys. J.}, title = {AEOS: Transport of metals from minihalos following population III stellar feedback}, volume = {980}, year = {2025}, }
• (2025). Quantifying baryonic feedback on the Warm–Hot circumgalactic medium in CAMELS simulations. ApJ, 980(1), 61. (www)

  @article{ , abstract = {The baryonic physics shaping galaxy formation and evolution are complex, spanning a vast range of scales and making them challenging to model. Cosmological simulations rely on subgrid models that produce significantly different predictions. Understanding how models of stellar and active galactic nucleus (AGN) feedback affect baryon behavior across different halo masses and redshifts is essential. Using the SIMBA and IllustrisTNG suites from the Cosmology and Astrophysics with MachinE Learning Simulations (CAMELS) project, we explore the effect of parameters governing the subgrid implementation of stellar and AGN feedback. We find that while IllustrisTNG shows higher cumulative feedback energy across all halos, SIMBA demonstrates a greater spread of baryons, quantified by the closure radius and circumgalactic medium (CGM) gas fraction. This suggests that feedback in SIMBA couples more effectively to baryons and drives them more efficiently within the host halo. There is evidence that the different feedback modes are highly interrelated in these subgrid models. The parameters controlling the stellar feedback efficiency significantly impact AGN feedback, as seen in the suppression of black hole mass growth and delayed activation of AGN feedback to higher-mass halos with increasing stellar feedback efficiency in both simulations. Additionally, the AGN feedback efficiency parameters affect the CGM gas fraction at low halo masses in SIMBA, hinting at complex, nonlinear interactions between the AGN and supernova feedback modes. Overall, we demonstrate that stellar and AGN feedback are intimately interwoven, especially at low redshift, due to subgrid implementation, resulting in halo property effects that might initially seem counterintuitive.}, archive = {J_ApJ}, author = {Isabel Medlock and Chloe Neufeld and Daisuke Nagai and Daniel Anglés-Alcázar and Shy Genel and Benjamin D. Oppenheimer and Xavier Sims and Priyanka Singh and Francisco Villaescusa-Navarro}, doi = {10.3847/1538-4357/ada442}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {61}, shortjournal = {The Astrophys. J.}, title = {Quantifying baryonic feedback on the Warm–Hot circumgalactic medium in CAMELS simulations}, volume = {980}, year = {2025}, }
• (2025). ALMA observations of solar spicules in a polar coronal hole. ApJ, 980(1), 60. (www)

  @article{ , abstract = {We report observations of solar spicules at millimeter wavelengths (mm- λ ) using the Atacama Large Millimeter/submillimeter Array (ALMA). These are supplemented by observations in optical, ultraviolet (UV), and extreme ultraviolet (EUV) wavelengths. The observations were made on 2018 December 25 of the northern polar coronal hole. ALMA obtained time-resolved imaging observations at wavelengths of 3 mm (100 GHz; 2 s cadence) and 1.25 mm (239 GHz; ≈2 minutes cadence) with an angular resolution of 2 \mathop{.}\limits^{\unicode{x02033}} 2 × 1 \mathop{.}\limits^{\unicode{x02033}} 3 and 1 \mathop{.}\limits^{\unicode{x02033}} 5 × 0 \mathop{.}\limits^{\unicode{x02033}} 7, respectively. Spicules observed at mm- λ are easily seen low in the chromosphere whereas spicules in UV bands are seen to extend higher. The spicules observed at mm- λ are seen in absorption against coronal EUV emission, allowing us to estimate the column depth of neutral hydrogen. Spicular emission at mm- λ , due to thermal free–free radiation, allows us to estimate the electron number density as a function of height. We find that spicule densities, inferred from the mm- λ data are uniquely insensitive to assumptions regarding the temperature of plasma in spicules. We suggest that the upward mass flux carried by spicules is unlikely to play a significant role in the mass budget of the solar corona and solar wind, and the transport of hot material into the corona by spicules may not play a significant role in coronal heating. However, the possibility that electric currents, fast kink and torsional waves, or other wave modes carried by spicules may play a role in transporting energy into the solar corona cannot be excluded.}, archive = {J_ApJ}, author = {T. S. Bastian and C. Alissandrakis and A. Nindos and M. Shimojo and S. M. White}, doi = {10.3847/1538-4357/ada445}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {60}, shortjournal = {The Astrophys. J.}, title = {ALMA observations of solar spicules in a polar coronal hole}, volume = {980}, year = {2025}, }
• (2025). Do unusually cold starburst galaxies exist? a case study. ApJ, 980(1), 59. (www)

  @article{ , abstract = {We report observations of CO( J = 9 → 8) and OH + ( N = 1 → 0) toward the four millimeter-selected lensed starburst galaxies SPT 2354−58, 0150−59, 0314−44, and 0452−50, using the Atacama Large Millimeter/submillimeter Array (ALMA) Atacama Compact Array, as part of a larger study of OH + in the early Universe. In this work, we use these observations for the main purpose of spectroscopic redshift measurements. For all sources except SPT 0452−50, we confirm the previously reported most likely redshifts, and we find typical CO and OH + properties for massive starbursts. For SPT 0452−50, we rule out the previously reported value of z = 2.0105, measuring a firm redshift of z = 5.0160 based on [O i ], [C ii ], H 2 O, and CO emission instead when adding in ancillary ALMA data. Previously, SPT 0452−50 was considered an outlier in relations between dust temperature, far-infrared luminosity, and redshift, which may have hinted at an unusually cold starburst with a dust temperature of only T dust = (21 ± 2) K. Instead, our new measurements suggest it to be among highly luminous massive dusty starbursts at z > 5, with rather typical properties within that population. We find a revised dust temperature of T dust = (76.2 ± 2.5) K, and an updated lensing-corrected far-infrared luminosity (42.5–122.5 μ m) of (2.35 {}_{-0.08}^{+0.09} ) × 10 13 L ⊙ , i.e., about an order of magnitude higher than previously reported. We thus do not find evidence for the existence of unusually cold starburst galaxies in the early Universe that were missed by previous selection techniques.}, archive = {J_ApJ}, author = {Dominik A. Riechers}, doi = {10.3847/1538-4357/ada4ac}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {59}, shortjournal = {The Astrophys. J.}, title = {Do unusually cold starburst galaxies exist? a case study}, volume = {980}, year = {2025}, }
• (2025). A 22 billion m⊙ black hole in holmberg 15A with keck KCWI spectroscopy and triaxial orbit modeling. ApJ, 980(1), 58. (www)

  @article{ , abstract = {Holmberg 15A (H15A), the brightest cluster galaxy of A85, has an exceptionally low central surface brightness even among local massive elliptical galaxies with distinct stellar cores, making it exceedingly challenging to obtain high-quality spectroscopy to detect a supermassive black hole (SMBH) at its center. Aided by the superb sensitivity and efficiency of KCWI at the Keck II Telescope, we have obtained spatially resolved stellar kinematics over a ∼100'' × 100'' contiguous field of H15A for this purpose. The velocity field exhibits a low-amplitude (∼20 km s −1 ) rotation along a kinematic axis that is prominently misaligned from the photometric major axis, a strong indicator that H15A is triaxially shaped with unequal lengths for the three principal axes. Using 2500 observed kinematic constraints, we perform extensive calculations of stellar orbits with the triaxial Schwarzschild code, TriOS, and search over ∼40,000 galaxy models to simultaneously determine the mass and intrinsic 3D shape parameters of H15A. We determine a ratio of p = 0.89 for the middle-to-long principal axes and q = 0.65 for the short-to-long principal axes. Our best estimate of the SMBH mass, {M}_{{\rm{BH}}}=(2.1{6}_{-0.18}^{+0.23})\times 1{0}^{10}{M}_{\odot } , makes H15A—along with NGC 4889—the galaxy hosting the most massive SMBHs known in the local Universe. Both SMBHs lie significantly above the mean M BH – σ scaling relation. Repeating the orbit modeling with the axisymmetrized version of TriOS produces worse fits to the KCWI kinematics and increases M BH to (2.55 ± 0.20) × 10 10 M ⊙ , which is still significantly below the M BH = (4.0 ± 0.8) × 10 10 M ⊙ reported in a prior axisymmetric study of H15A.}, archive = {J_ApJ}, author = {Emily R. Liepold and Chung-Pei Ma and Jonelle L. Walsh}, doi = {10.3847/1538-4357/ada4b0}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {58}, shortjournal = {The Astrophys. J.}, title = {A 22 billion m⊙ black hole in holmberg 15A with keck KCWI spectroscopy and triaxial orbit modeling}, volume = {980}, year = {2025}, }
• (2025). Multi-observatory study of young stellar energetic flares (MORYSEF): No evidence for abnormally strong stellar magnetic fields after powerful X-ray flares. ApJ, 980(1), 57. (www)

  @article{ , abstract = {We explore the empirical power-law relationship between X-ray luminosity ( L X ) and total surface magnetic flux (Φ), established across solar magnetic elements, time- and disk-averaged emission from the Sun, older active stars, and pre-main-sequence (PMS) stars. Previous models of large PMS X-ray flares, lacking direct magnetic field measurements, showed discrepancies from this baseline law, which MHD simulations attribute to unusually strong magnetic fields during flares. To test this, we used nearly simultaneous Chandra X-ray and HET-HPF near-infrared observations of four young Orion stars, measuring surface magnetic fields during or just after powerful PMS X-ray flares. We also modeled these PMS X-ray flares, incorporating their measured magnetic field strengths. Our findings reveal magnetic field strengths at the stellar surface typical of nonflaring PMS stars, ruling out the need for abnormally strong fields during flares. Both PMS and solar flares deviate from the L X –Φ law, with PMS flares exhibiting a more pronounced deviation, primarily due to their much larger active regions on the surface and larger flaring loop volumes above the surface compared to their solar counterparts. These deviations likely stem from the fact that powerful flares are driven by magnetic reconnection, while baseline X-ray emission may involve less efficient mechanisms like Alfvén wave heating. Our results also indicate a preference for dipolar magnetic loops in PMS flares, consistent with Zeeman–Doppler imaging of fully convective stars. This requirement for giant dipolar loops aligns with MHD predictions of strong dipoles supported by polar magnetic surface active regions in fast-rotating, fully convective stars.}, archive = {J_ApJ}, author = {Konstantin V. Getman and Oleg Kochukhov and Joe P. Ninan and Eric D. Feigelson and Vladimir S. Airapetian and Abygail R. Waggoner and L. Ilsedore Cleeves and Jan Forbrich and Sergio A. Dzib and Charles J. Law and Christian Rab and Daniel M. Krolikowski}, doi = {10.3847/1538-4357/ada55c}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {57}, shortjournal = {The Astrophys. J.}, title = {Multi-observatory study of young stellar energetic flares (MORYSEF): No evidence for abnormally strong stellar magnetic fields after powerful X-ray flares}, volume = {980}, year = {2025}, }
• (2025). Sporadic dips from extended debris transiting the metal-rich white dwarf SBSS 1232+563. ApJ, 980(1), 56. (www)

  @article{ , abstract = {We present the discovery of deep but sporadic transits in the flux of SBSS 1232+563, a metal-rich white dwarf polluted by disrupted exoplanetary debris. Nearly 25 yr of photometry from multiple sky surveys reveal evidence of occasional dimming of the white dwarf, most notably evident in an 8 month long event in 2023 that caused a >40% drop in flux from the star. In-transit follow-up shows additional short-timescale (minutes- to hours-long) dimming events. Transiting Exoplanet Survey Satellite photometry suggests a coherent 14.842 hr signal that could represent the dominant orbital period of debris. Six low-resolution spectra collected at various transit depths over two decades show no evidence of significant changes in the observed elemental abundances. SBSS 1232+563 demonstrates that debris transits around white dwarfs can be sporadic, with many years of inactivity before large-amplitude dimming events.}, archive = {J_ApJ}, author = {J. J. Hermes and Joseph A. Guidry and Zachary P. Vanderbosch and Mariona Badenas-Agusti and Siyi Xu and Malia L. Kao and Antonio C. Rodriguez and Keith Hawkins}, doi = {10.3847/1538-4357/ada5fd}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {56}, shortjournal = {The Astrophys. J.}, title = {Sporadic dips from extended debris transiting the metal-rich white dwarf SBSS 1232+563}, volume = {980}, year = {2025}, }
• (2025). Relativistic binary precession: Impact on eccentric massive binary black hole accretion and hydrodynamics. ApJ, 980(1), 55. (www)

  @article{ , abstract = {Recent hydrodynamical simulations have shown that circumbinary gas disks drive the orbits of massive binary black holes (BHs) to become eccentric, even when general relativistic (GR) corrections to the orbit are significant. Here, we study the GR apsidal precession of eccentric equal-mass massive binary BHs in circumbinary disks via two-dimensional hydrodynamical simulations. We perform a suite of simulations comparing precessing and nonprecessing binaries across a range of eccentricities, semimajor axes, and precession rates. We find that the GR precession of the binary's semimajor axis can introduce a dominant modulation in the binary's accretion rate and the corresponding high-energy electromagnetic light curves. We discuss the conditions under which this occurs and its detailed characteristics and mechanism. Finally, we discuss the potential to observe these precession signatures in electromagnetic- and gravitational-wave observations, as well as the precession signal's unique importance as a potential tool to constrain the mass, eccentricity, and semimajor axis of binary merger events.}, archive = {J_ApJ}, author = {Stanislav DeLaurentiis and Zoltán Haiman and John Ryan Westernacher-Schneider and Luke Major Krauth and Jordy Davelaar and Jonathan Zrake and Andrew MacFadyen}, doi = {10.3847/1538-4357/ada612}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {55}, shortjournal = {The Astrophys. J.}, title = {Relativistic binary precession: Impact on eccentric massive binary black hole accretion and hydrodynamics}, volume = {980}, year = {2025}, }
• (2025). Influence of effective nucleon mass on equation of state for supernova simulations and neutron stars. ApJ, 980(1), 54. (www)

  @article{ , abstract = {We investigate the influence of the effective nucleon mass on the equation of state (EOS), which is constructed for simulations of core-collapse supernovae and binary neutron star mergers, within the relativistic mean-field (RMF) framework. The study introduces a new RMF parameter set, TM1m, which is a modification of the TM1e model with an adjusted effective mass, maintaining the saturation properties of nuclear matter. The TM1m model, with a larger effective mass ratio ( M * / M ~ 0.8) compared to the TM1e model ( M * / M ~ 0.63), is employed to construct a new EOS table, EOS5. This EOS table is designed to offer insights into the influence of the effective nucleon mass on the EOS within a relativistic framework, particularly above the saturation density. The results of EOS5 are compared with those obtained from other models, including both relativistic and nonrelativistic approaches. The properties of cold neutron stars, calculated using the TM1m model, are compatible with the existence of a 2 M ⊙ pulsar and the latest constraints on the tidal deformability and radii of a canonical 1.4 M ⊙ neutron star, derived from astrophysical observations.}, archive = {J_ApJ}, author = {Shuying Li and Junbo Pang and Hong Shen and Jinniu Hu and Kohsuke Sumiyoshi}, doi = {10.3847/1538-4357/ada6b3}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {54}, shortjournal = {The Astrophys. J.}, title = {Influence of effective nucleon mass on equation of state for supernova simulations and neutron stars}, volume = {980}, year = {2025}, }
• (2025). Black hole supernovae, their equation of state dependence, and ejecta composition. ApJ, 980(1), 53. (www)

  @article{ , abstract = {Recent literature on core-collapse supernovae suggests that a black hole (BH) can form within ∼1 s of shock revival, while still culminating in a successful supernova. We refer to these as BH supernovae, as they are distinct from other BH formation channels in both timescale and impact on the explosion. We simulate these events self-consistently from core collapse until 20–50 days after collapse using three axisymmetric models of a 60 M ⊙ zero-age main-sequence progenitor star and investigate how the composition of the ejecta is impacted by the BH formation. We employ Skyrme-type equations of state (EOSs) and vary the uncertain nucleonic effective mass, which affects the pressure inside the proto–neutron star through the thermal part of the EOS. This results in different BH formation times and explosion energies at BH formation, yielding final explosion energies between 0.06 and 0.72 × 10 51 erg with 21.8–23.3 M ⊙ of ejecta, of which 0–0.018 M ⊙ is 56 Ni. Compared to expectations from 1D simulations, we find more nuanced EOS dependences of the explosion dynamics, the mass of the BH remnant, and the elemental composition of the ejecta. We investigate why the explosions survive despite the massive overburden and link the shape of the diagnostic energy curve and character of the ejecta evolution to the progenitor structure.}, archive = {J_ApJ}, author = {Oliver Eggenberger Andersen and Evan O’Connor and Haakon Andresen and André da Silva Schneider and Sean M. Couch}, doi = {10.3847/1538-4357/ada899}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {53}, shortjournal = {The Astrophys. J.}, title = {Black hole supernovae, their equation of state dependence, and ejecta composition}, volume = {980}, year = {2025}, }
• (2025). Exploring magnetic fields in molecular clouds through denoising diffusion probabilistic models. ApJ, 980(1), 52. (www)

  @article{ , abstract = {Accurately measuring magnetic field strength in the interstellar medium, including giant molecular clouds, remains a significant challenge. We present a machine learning approach using denoising diffusion probabilistic models (DDPMs) to estimate magnetic field strength from synthetic observables such as column density, orientation angles of the dust continuum polarization vector, and line-of-sight (LOS) nonthermal velocity dispersion. We trained three versions of the DDPM model: the 1-channel DDPM (using only column density), the 2-channel DDPM (incorporating both column density and polarization angles), and the 3-channel DDPM (which combines column density, polarization angles, and LOS nonthermal velocity dispersion). The code and trained model are available on GitHub at https://github.com/xuduo117/DDPM_Bmag . We assessed the models on both synthetic test samples and new simulation data that were outside the training set's distribution. The 3-channel DDPM consistently outperformed both the other DDPM variants and the power-law fitting approach based on column density alone, demonstrating its robustness in handling previously unseen data. Additionally, we compared the performance of the Davis–Chandrasekhar–Fermi (DCF) methods, both classical and modified, to the DDPM predictions. The classical DCF method overestimated the magnetic field strength by approximately an order of magnitude. Although the modified DCF method showed improvement over the classical version, it still fell short of the precision achieved by the 3-channel DDPM.}, archive = {J_ApJ}, author = {Duo Xu and Jenna Karcheski and Chi-Yan Law and Ye Zhu and Chia-Jung Hsu and Jonathan C. Tan}, doi = {10.3847/1538-4357/ada8a0}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {52}, shortjournal = {The Astrophys. J.}, title = {Exploring magnetic fields in molecular clouds through denoising diffusion probabilistic models}, volume = {980}, year = {2025}, }
• (2025). Long-term evolution of sco X-1: Implications for the current spin frequency and ellipticity of the neutron star. ApJ, 980(1), 51. (www)

  @article{ , abstract = {Sco X-1 is the brightest observed extrasolar X-ray source, which is a neutron star (NS) low-mass X-ray binary (LMXB) and is thought to have a strong potential for continuous gravitational waves (CW) detection due to its high accretion rate and relative proximity. Here, we compute the long-term evolution of its parameters, particularly the NS spin frequency ( ν ) and the surface magnetic field ( B ), to probe its nature and its potential for CW detection. We find that Sco X-1 is an unusually young (∼7 × 10 6 yr) LMXB and constrain the current NS mass to ∼1.4–1.6 M ⊙ . Our computations reveal a rapid B decay, with the maximum current value of ∼1.8 × 10 8 G, which can be useful to constrain the decay models. Note that the maximum current ν value is ∼550 Hz, implying that, unlike what is generally believed, a CW emission is not required to explain the current source properties. However, ν will exceed an observed cutoff frequency of ∼730 Hz, and perhaps even the NS breakup frequency, in the future without a CW emission. The minimum NS mass quadrupole moment ( Q ) to avoid this is ∼(2–3) × 10 37 g cm 2 , corresponding to a CW strain of ∼10 −26 . Our estimation of current ν values can improve the CW search sensitivity.}, archive = {J_ApJ}, author = {Abhijnan Kar and Pulkit Ojha and Sudip Bhattacharyya}, doi = {10.3847/1538-4357/adabbf}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {51}, shortjournal = {The Astrophys. J.}, title = {Long-term evolution of sco X-1: Implications for the current spin frequency and ellipticity of the neutron star}, volume = {980}, year = {2025}, }
• (2025). Dust scattering albedo at millimeter wavelengths in the TW hya disk. ApJ, 980(1), 50. (www)

  @article{ , abstract = {Planetary bodies are formed by coagulation of solid dust grains in protoplanetary disks. Therefore, it is crucial to constrain the physical and chemical properties of the dust grains. In this study, we measure the dust albedo at millimeter wavelength, which depends on dust properties at the disk midplane. Since the albedo and dust temperature are generally degenerate in observed thermal dust emission, it is challenging to determine them simultaneously. We propose to break this degeneracy by using multiple optically thin molecular lines as a dust–albedo-independent thermometer. In practice, we employ pressure-broadened CO line wings that provide an exceptionally high signal-to-noise ratio as an optically thin line. We model the CO J = 2–1 and 3–2 spectra observed by the Atacama Large Millimeter/submillimeter Array at the inner region ( r < 6 au) of the TW Hya disk and successfully derive the midplane temperature. Combining multiband continuum observations, we constrain the albedo spectrum at 0.9–3 mm for the first time without assuming a dust opacity model. The albedo at these wavelengths is high, ~0.5–0.8, and broadly consistent with the L. Ricci et al., DIANA, and DSHARP dust models. Even without assuming dust composition, we estimate the maximum grain size to be ~340 μ m, the power-law index of the grain size distribution to be >−4.1, and the porosity to be <0.96. The derived dust size may suggest efficient fragmentation with a threshold velocity of ~0.08 m s −1 . We also note that the absolute flux uncertainty of ~10% (1 σ ) is measured and used in the analysis, which is approximately twice the usually assumed value.}, archive = {J_ApJ}, author = {Tomohiro C. Yoshida and Hideko Nomura and Takashi Tsukagoshi and Kiyoaki Doi and Kenji Furuya and Akimasa Kataoka}, doi = {10.3847/1538-4357/ad9f31}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {50}, shortjournal = {The Astrophys. J.}, title = {Dust scattering albedo at millimeter wavelengths in the TW hya disk}, volume = {980}, year = {2025}, }
• (2025). JWST imaging of edge-on protoplanetary disks. IV. mid-infrared dust scattering in the HH 30 disk. ApJ, 980(1), 49. (www)

  @article{ , abstract = {We present near- and mid-infrared (IR) broadband imaging observations of the edge-on protoplanetary disk around HH 30 with the James Webb Space Telescope/Near Infrared Camera and the Mid-Infrared Instrument (MIRI). We combine these observations with archival optical/near-IR scattered light images obtained with the Hubble Space Telescope and a millimeter-wavelength dust continuum image obtained with the Atacama Large Millimeter/submillimeter Array (ALMA) with the highest spatial resolution ever obtained for this target. Our multiwavelength images clearly reveal the vertical and radial segregation of micron-sized and submillimeter-sized grains in the disk. In the near- and mid-IR, the images capture not only bireflection nebulae separated by a dark lane but also diverse dynamical processes occurring in the HH 30 disk, such as spiral- and tail-like structures, a conical outflow, and a collimated jet. In contrast, the ALMA image reveals a flat dust disk in the disk midplane. By performing radiative transfer simulations, we show that grains of about 3 μ m in radius or larger are fully vertically mixed to explain the observed mid-IR scattered light flux and its morphology, whereas millimeter-sized grains are settled into a layer with a scale height of ≳1 au at 100 au from the central star. We also find a tension in the disk inclination angle inferred from optical/near-IR and millimeter observations, with the latter being closer to exactly edge-on. Finally, we report the first detection of the proper motion of an emission knot associated with the mid-IR collimated jet detected by combining two epochs of our MIRI 12.8 μ m observations.}, archive = {J_ApJ}, author = {Ryo Tazaki and François Ménard and Gaspard Duchêne and Marion Villenave and Álvaro Ribas and Karl R. Stapelfeldt and Marshall D. Perrin and Christophe Pinte and Schuyler G. Wolff and Deborah L. Padgett and Jie Ma and Laurine Martinien and Maxime Roumesy}, doi = {10.3847/1538-4357/ad9c6f}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {49}, shortjournal = {The Astrophys. J.}, title = {JWST imaging of edge-on protoplanetary disks. IV. mid-infrared dust scattering in the HH 30 disk}, volume = {980}, year = {2025}, }
• (2025). Strong-lensing analysis of SPT-CL j2325−4111 and SPT-CL j0049−2440, two powerful cosmic telescopes (RE > 40″) from the SPT clusters sample. ApJ, 980(1), 48. (www)

  @article{ , abstract = {We report the results from a study of two massive ( M 500 c > 6.0 × 10 14 M ⊙ ) strong-lensing clusters selected from the South Pole Telescope cluster survey for their large Einstein radius ( R E > 40''), SPT-CL J2325−4111 and SPT-CL J0049−2440. Ground-based and shallow Hubble Space Telescope (HST) imaging indicated extensive strong-lensing evidence in these fields, with giant arcs spanning 18'' and 31'', respectively, motivating further space-based imaging follow-up. Here, we present multiband HST imaging and ground-based Magellan spectroscopy of the fields, from which we compile detailed strong-lensing models. The lens models of SPT-CL J2325−4111 and SPT-CL J0049−2440 were optimized using nine and eight secure multiply imaged systems with a final image-plane rms of 0 \mathop{.}\limits^{^{\prime\prime} } 63 and 0 \mathop{.}\limits^{^{\prime\prime} } 73, respectively. From the lensing analysis, we measure a projected mass density within 500 kpc of M (<500 kpc) = (7.30 ± 0.07) × 10 14 M ⊙ and M(\lt 500\,\mathrm{kpc})=7.1{2}_{-0.19}^{+0.16}\times 1{0}^{14} M ⊙ for these two clusters, and subhalo mass ratios of 0.12 ± 0.01 and 0.2{1}_{-0.05}^{+0.07} , respectively. Both clusters produce a large area with high magnification ( μ ≥ 3) for a source at z = 9, {{ \mathcal A }}_{|\mu |\geqslant 3}^{{\rm{lens}}}=4.9{3}_{-0.04}^{+0.03} arcmin 2 and {{ \mathcal A }}_{|\mu |\geqslant 3}^{{\rm{lens}}}=3.6{4}_{-0.10}^{+0.14} arcmin 2 , respectively, placing them in the top tier of strong-lensing clusters. We conclude that these clusters are spectacular sightlines for further observations that will reduce the systematic uncertainties due to cosmic variance. This paper provides the community with two additional well-calibrated cosmic telescopes, as strong as the Frontier Fields and suitable for studies of the highly magnified background Universe.}, archive = {J_ApJ}, author = {Guillaume Mahler and Keren Sharon and Matthew Bayliss and Lindsey. E. Bleem and Mark Brodwin and Benjamin Floyd and Raven Gassis and Michael D. Gladders and Gourav Khullar and Juan D. Remolina González and Arnab Sarkar}, doi = {10.3847/1538-4357/ad9aa5}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {48}, shortjournal = {The Astrophys. J.}, title = {Strong-lensing analysis of SPT-CL j2325−4111 and SPT-CL j0049−2440, two powerful cosmic telescopes (RE > 40″) from the SPT clusters sample}, volume = {980}, year = {2025}, }
• (2025). Observations of microlensed images with dual-field interferometry: On-sky demonstration and prospects. ApJ, 980(1), 47. (www)

  @article{ , abstract = {Interferometric observations of gravitational microlensing events offer an opportunity for precise, efficient, and direct mass and distance measurements of lensing objects, especially those of isolated neutron stars and black holes. However, such observations have previously been possible for only a handful of extremely bright events. The recent development of a dual-field interferometer, GRAVITY Wide, has made it possible to reach out to significantly fainter objects and increase the pool of microlensing events amenable to interferometric observations by 2 orders of magnitude. Here, we present the first successful observation of a microlensing event with GRAVITY Wide and the resolution of microlensed images in the event OGLE-2023-BLG-0061/KMT-2023-BLG-0496. We measure the angular Einstein radius of the lens with subpercent precision, θ E = 1.280 ± 0.009 mas. Combined with the microlensing parallax detected from the event light curve, the mass and distance to the lens are found to be 0.472 ± 0.012 M ⊙ and 1.81  ±  0.05 kpc, respectively. We present the procedure for the selection of targets for interferometric observations and discuss possible systematic effects affecting GRAVITY Wide data. This detection demonstrates the capabilities of the new instrument, and it opens up completely new possibilities for the follow-up of microlensing events and future routine discoveries of isolated neutron stars and black holes.}, archive = {J_ApJ}, author = {Przemek Mróz and Subo Dong and Antoine Mérand and Jinyi Shangguan and Julien Woillez and Andrew Gould and Andrzej Udalski and Frank Eisenhauer and Yoon-Hyun Ryu and Zexuan Wu and Zhuokai Liu and Hongjing Yang and — and Guillaume Bourdarot and Denis Defrère and Antonia Drescher and Maximilian Fabricius and Paulo Garcia and Reinhard Genzel and Stefan Gillessen and Sebastian F. Hönig and Laura Kreidberg and Jean-Baptiste Le Bouquin and Dieter Lutz and Florentin Millour and Thomas Ott and Thibaut Paumard and Jonas Sauter and T. Taro Shimizu and Christian Straubmeier and Matthias Subroweit and Felix Widmann and (The GRAVITY+ Collaboration) and Michał K. Szymański and Igor Soszyński and Paweł Pietrukowicz and Szymon Kozłowski and Radosław Poleski and Jan Skowron and Krzysztof Ulaczyk and Mariusz Gromadzki and Krzysztof Rybicki and Patryk Iwanek and Marcin Wrona and Mateusz J. Mróz and (The OGLE Collaboration) and Michael D. Albrow and Sun-Ju Chung and Cheongho Han and Kyu-Ha Hwang and Youn Kil Jung and In-Gu Shin and Yossi Shvartzvald and Jennifer C. Yee and Weicheng Zang and Sang-Mok Cha and Dong-Jin Kim and Seung-Lee Kim and Chung-Uk Lee and Dong-Joo Lee and Yongseok Lee and Byeong-Gon Park and Richard W. Pogge and (KMTNet Collaboration)}, doi = {10.3847/1538-4357/ad9b14}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {47}, shortjournal = {The Astrophys. J.}, title = {Observations of microlensed images with dual-field interferometry: On-sky demonstration and prospects}, volume = {980}, year = {2025}, }
• (2025). A search for radio millisecond pulsar companions around extremely low-mass white dwarfs with ellipsoidal variability. ApJ, 980(1), 46. (www)

  @article{ , abstract = {Extremely low-mass (ELM) white dwarfs (WDs) are helium-core WDs with masses less than 0.3 M ⊙ . Short-period ELM WD binaries that exhibit ellipsoidal variations may harbor heavier companions, either massive WDs or millisecond pulsars (MSPs). In this study, we selected ∼12,000 ELM WDs or their candidates, and searched for ellipsoidal-like lightcurves with orbital periods shorter than 1 day, by using the public data from Zwicky Transient Facility. Finally, 23 such systems were found, with 17 being newly discovered. We selected nine high-priority targets likely to evolve from the Roche lobe overflow channel and estimated their companion masses from the extracted ellipsoidal variation amplitude. Among them, four targets have companion masses exceeding 1 M ⊙ . We performed a search for radio pulsations from six of these targets by using Five-hundred-meter Aperture Spherical radio Telescope. However, no convincing radio pulse signals were found, resulting in upper limits for the radio flux at around 8 μ Jy. Given the nondetection of radio pulsations from a total of 11 similar systems, the fraction of ellipsoidal ELM WDs around MSPs is estimated to be below 15 {}_{-3}^{+6} %. We anticipate that multiwavelength studies of more ellipsoidal-like ELM WDs will further constrain the fraction.}, archive = {J_ApJ}, author = {W. J. Huang and Pak-Hin Thomas Tam and L. L. Ren and J. M. Lin}, doi = {10.3847/1538-4357/ad9de5}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {46}, shortjournal = {The Astrophys. J.}, title = {A search for radio millisecond pulsar companions around extremely low-mass white dwarfs with ellipsoidal variability}, volume = {980}, year = {2025}, }
• (2025). Analysis of the internal radial gradient of chemical abundances in spiral galaxies from CALIFA. ApJ, 980(1), 45. (www)

  @article{ , abstract = {The study of chemical evolution is of paramount importance for understanding the evolution of galaxies. Models and observations propose an inside-out mechanism in the formation of spiral galaxy disks, implying a negative radial gradient of elemental abundances when represented on a logarithmic scale. However, in some instances, the observed chemical abundance gradients deviate from a single negative straight line, revealing inner drops or outer flattenings, particularly in more massive galaxies. This study analyzes oxygen abundance gradients in spiral galaxies based on observations from the Calar Alto Legacy Integral Field Area survey. Our focus is specifically on examining oxygen abundance gradient profiles, as obtained with data from H ii regions, with a special emphasis on the inner radial gradient. We employ an automated fitting procedure to establish correlations between the physical properties of galaxies and bulges and the presence of these inner drops, seeking potential explanations for these variations in gradient. We find that the different criteria used in the literature to distinguish H ii regions from other ionization sources in the galaxies, such as active galactic nuclei, significantly impact the results, potentially altering abundance gradient profiles and uncovering galaxies with distinct inner drops. Additionally, we analyze the abundance radial gradients to investigate the impact of diffuse ionized gas (DIG) decontamination on oxygen abundances over these inner drops. We observe that DIG, concentrated mainly in the central regions of galaxies, can modify oxygen abundance gradient profiles if left unaddressed.}, archive = {J_ApJ}, author = {A. F. S. Cardoso and O. Cavichia and M. Mollá and L. Sánchez-Menguiano}, doi = {10.3847/1538-4357/ad9eab}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {45}, shortjournal = {The Astrophys. J.}, title = {Analysis of the internal radial gradient of chemical abundances in spiral galaxies from CALIFA}, volume = {980}, year = {2025}, }
• (2025). ALMA observations of massive clouds in the central molecular zone: External-pressure-confined dense cores and salpeter-like core mass functions. ApJ, 980(1), 44. (www)

  @article{ , abstract = {We present Atacama Large Millimeter/submillimeter Array Band 6 (1.3 mm) observations of dense cores in three massive molecular clouds within the central molecular zone (CMZ) of the Milky Way, including the Dust Ridge cloud e, Sgr C, and the 20 km s −1 cloud, at a spatial resolution of 2000 au. Among the 834 cores identified from the 1.3 mm continuum, we constrain temperatures and linewidths of 253 cores using local thermodynamic equilibrium methods to fit the H 2 CO and/or CH 3 CN spectra. We determine their masses using the 1.3 mm dust continuum and derived temperatures, and then evaluate their virial parameters using the H 2 CO and/or CH 3 CN linewidths and construct the core mass functions (CMFs). We find that the contribution of external pressure is crucial for the virial equilibrium of the dense cores in the three clouds, which contrasts with the environment in the Galactic disk where dense cores are already bound, even without the contribution of external pressure. With our new temperature estimates we also find that the CMFs show a Salpeter-like slope in the high-mass (≳3–6 M ⊙ ) end, a change from previous works. Combined with the possible top-heavy initial mass functions (IMFs) in the CMZ, our result suggests that gas accretion and further fragmentation may play important roles in transforming the CMF to the IMF.}, archive = {J_ApJ}, author = {Zhenying Zhang and Xing Lu and Tie Liu and Sheng-Li Qin and Adam Ginsburg and Yu Cheng and Hauyu Baobab Liu and Daniel L. Walker and Xindi Tang and Shanghuo Li and Qizhou Zhang and Thushara Pillai and Jens Kauffmann and Cara Battersby and Siyi Feng and Suinan Zhang and Qi-Lao Gu and Fengwei Xu and Wenyu Jiao and Xunchuan Liu and Li Chen and Qiu-yi Luo and Xiaofeng Mai and Zi-yang Li and Dongting Yang and Xianjin Shen and Meizhu Liu and Zhiqiang Shen}, doi = {10.3847/1538-4357/ad9f28}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {44}, shortjournal = {The Astrophys. J.}, title = {ALMA observations of massive clouds in the central molecular zone: External-pressure-confined dense cores and salpeter-like core mass functions}, volume = {980}, year = {2025}, }
• (2025). Revisiting near-infrared features of kilonovae: The importance of gadolinium. ApJ, 980(1), 43. (www)

  @article{ , abstract = {The observation of the kilonova AT2017gfo and investigations of its light curves and spectra confirmed that neutron star mergers are sites of r -process nucleosynthesis. However, the identification of elements responsible for the spectral features is still challenging, particularly at the near-infrared wavelengths. In this study, we systematically searched for all possible near-infrared transitions of heavy elements using experimentally calibrated energy levels. Our analysis reveals that most candidate elements with strong absorption lines are lanthanides ( Z = 57–71) and actinides ( Z = 89–103). This is due to their complex structures leading to many low-lying energy levels, which results in strong transitions in the near-infrared range. N. Domoto et al. (2022) have shown that La iii and Ce iii can explain the absorption features at λ ∼ 12000–15000 Å. While our results confirm that these two elements show strong infrared features, we additionally identify Gd iii as the next most promising species. Due to its unique atomic structure involving the half-filled 4 f and the outer 5 d orbitals, Gd iii has one of the lowest-lying energy levels, between which relatively strong transitions occur. We also find absorption lines caused by Gd iii in the near-infrared spectrum of a chemically peculiar star HR 465, which supports their emergence in kilonova spectra. By performing radiative transfer simulations, we confirm that Gd iii lines affect the feature at ∼12000 Å previously attributed to La iii . Future space-based time-series observations of kilonova spectra will allow the identification of Gd iii lines.}, archive = {J_ApJ}, author = {Salma Rahmouni and Masaomi Tanaka and Nanae Domoto and Daiji Kato and Kenta Hotokezaka and Wako Aoki and Teruyuki Hirano and Takayuki Kotani and Masayuki Kuzuhara and Motohide Tamura}, doi = {10.3847/1538-4357/ada251}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {43}, shortjournal = {The Astrophys. J.}, title = {Revisiting near-infrared features of kilonovae: The importance of gadolinium}, volume = {980}, year = {2025}, }
• (2025). The magnetic origin of the mystery of rare hα moreton waves. ApJ, 980(1), 42. (www)

  @article{ , abstract = {Over the past three decades, a lot of coronal fast-mode waves have been detected by space missions, but their counterparts in the chromosphere, called Moreton waves, have rarely been captured. How this happens remains a mystery. Here, to shed light on this problem, we investigate the photospheric vector magnetograms of the Moreton-wave events associated with M- and X-class solar flares during 2010–2023. The H α data are taken with the Global Oscillation Network Group and the Chinese H α Solar Explorer. Our statistical results show that more than 80% of the events occur at the edges of active regions and propagate nonradially, due to asymmetric magnetic fields above the flares. According to the reconstructed magnetic field and atmospheric model, Moreton waves propagate in the direction along which the horizontal fast-mode wave speed drops the fastest. This result supports the inclined magnetic configuration of the eruption being crucial for generating Moreton waves, even for X-class flares. It may explain the low occurrence rate of Moreton waves and why some X-class flares accompanied with coronal mass ejections do not generate Moreton waves.}, archive = {J_ApJ}, author = {Ze Zhong and Yao Chen and Y. W. Ni and P. F. Chen and Ruisheng Zheng and Xiangliang Kong and Chuan Li}, doi = {10.3847/1538-4357/ada387}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {42}, shortjournal = {The Astrophys. J.}, title = {The magnetic origin of the mystery of rare hα moreton waves}, volume = {980}, year = {2025}, }
• (2025). AEOS: Star-by-star cosmological simulations of early chemical enrichment and galaxy formation. ApJ, 980(1), 41. (www)

  @article{ , abstract = {The A eos project introduces a series of high-resolution cosmological simulations that model star-by-star chemical enrichment and galaxy formation in the early Universe, achieving 1 pc resolution. These simulations capture the complexities of galaxy evolution within the first ~300 Myr by modeling individual stars and their feedback processes. By incorporating chemical yields from individual stars, A eos generates galaxies with diverse stellar chemical abundances, linking them to hierarchical galaxy formation and early nucleosynthetic events. These simulations underscore the importance of chemical abundance patterns in ancient stars as vital probes of early nucleosynthesis, star formation histories, and galaxy formation. We examine the metallicity floors of various elements resulting from Population III enrichment, providing best-fit values for eight different metals (e.g., [O/H] = −4.0) to guide simulations without Population III models. Additionally, we identify galaxies that begin star formation with Population II after external enrichment and investigate the frequency of carbon-enhanced metal-poor stars at varying metallicities. The A eos simulations offer detailed insights into the relationship between star formation, feedback, and chemical enrichment. Future work will extend these simulations to later epochs to interpret the diverse stellar populations of the Milky Way and its satellites.}, archive = {J_ApJ}, author = {Kaley Brauer and Andrew Emerick and Jennifer Mead and Alexander P. Ji and John H. Wise and Greg L. Bryan and Mordecai-Mark Mac Low and Benoit Côté and Eric P. Andersson and Anna Frebel}, doi = {10.3847/1538-4357/ada4a1}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {41}, shortjournal = {The Astrophys. J.}, title = {AEOS: Star-by-star cosmological simulations of early chemical enrichment and galaxy formation}, volume = {980}, year = {2025}, }
• (2025). Signatures of core-envelope rotational misalignment in the mixed-mode asteroseismology of kepler-56. ApJ, 980(1), 40. (www)

  @article{ , abstract = {Existing asteroseismic rotational measurements assume that stars rotate around a single axis. However, tidal torques from misaligned companions, or their possible engulfment, may bring the rotational axis of a star's envelope out of alignment with its core, breaking azimuthal symmetry. I derive perturbative expressions for asteroseismic signatures of such hitherto unexamined rotational configurations, under the "shellular approximation" of constant rotation rates on radially stratified mass shells. In the aligned case, the distribution of power between multiplet components is determined by the inclination of the rotational axis; radial differential misalignment causes this to vary from multiplet to multiplet. I examine in particular detail the phenomenology of gravitoacoustic mixed modes as seen in evolved sub- and red giants, where near-resonance avoided crossings may break geometrical degeneracies. Upon applying the revised asteroseismic observational methodology that results from this theoretical discussion to revisit Kepler-56—a red giant with a misaligned planetary system—I find that its core and envelope rotate around different rotational axes. While the rotational axis of its core is indeed misaligned from the orbit normal of its transiting planets (consistently with earlier studies), its envelope's rotational axis is close to lying in the sky plane, and may well be aligned with them. More detailed asteroseismic modeling, and spectroscopic follow-up, will be required to fully elucidate the full spin–orbit geometry of the Kepler-56 system, and potentially discriminate between hypotheses for how it formed.}, archive = {J_ApJ}, author = {J. M. Joel Ong}, doi = {10.3847/1538-4357/ada4a3}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {40}, shortjournal = {The Astrophys. J.}, title = {Signatures of core-envelope rotational misalignment in the mixed-mode asteroseismology of kepler-56}, volume = {980}, year = {2025}, }
• (2025). The dynamical history of HIP-41378 f—Oblique exorings masquerading as a puffy planet. ApJ, 980(1), 39. (www)

  @article{ , abstract = {The super-puff HIP-41378 f represents a fascinating puzzle due to its anomalously low density on a far-out orbit in contrast with other known super-puffs. In this work, we explore the hypothesis that HIP-41378 f is not in fact a low-density planet, but rather hosts an opaque ring system. We analyze the dynamical history of the system and show that convergent migration is necessary to explain the system's long-term stability. We then show that this same migration process plausibly captures HIP-41378 f into spin–orbit resonance and excites the planetary obliquity to high values. This tilts the surrounding ring and is a plausible explanation for the large transit depth. In the end, we also briefly comment on the likelihood of other super-puff planets being in high-obliquity states. We show that the existence of a tilted extensive ring around a high obliquity planet can serve as an explanation for puffy planets, particularly in multiplanetary systems at far distances from their host stars.}, archive = {J_ApJ}, author = {Tiger Lu and Gongjie Li and Ben Cassese and D. N. C. Lin}, doi = {10.3847/1538-4357/ada4b2}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {39}, shortjournal = {The Astrophys. J.}, title = {The dynamical history of HIP-41378 f—Oblique exorings masquerading as a puffy planet}, volume = {980}, year = {2025}, }
• (2025). Systematic search for long-term trends in fermi-LAT jetted active galactic nuclei. ApJ, 980(1), 38. (www)

  @article{ , abstract = {Jetted active galactic nuclei (AGN) exhibit variability across a wide range of timescales. Traditionally, this variability can often be modeled well as a stochastic process. However, in certain cases, jetted AGN variability displays regular patterns, enabling us to conduct investigations aimed at understanding its origins. Additionally, a novel type of variability has emerged in jetted AGN light curves, specifically, the observation of a long-term trend characterized by a linear increase of the flux with time in blazars such as PG 1553+113, which is among the objects most likely to display periodic behavior. In this paper, we present the results of a systematic search for long-term trends, spanning ≈10 yr, utilizing 12 yr of Fermi-LAT observations. The study is focused on detecting the presence of linear or quadratic long-term trends in a sample of 3308 jetted AGN. Our analysis has identified 40 jetted AGN that exhibit long-term trends, each with distinct properties, which we also characterize in this study. These long-term trends may originate from the dynamics of a supermassive black hole binary system, or they could be the result of intrinsic phenomena within the jet itself. Our findings can help in addressing questions pertaining to the astrophysical origins of variability and periodicity within jetted AGN.}, archive = {J_ApJ}, author = {P. Peñil and A. Domínguez and S. Buson and M. Ajello and S. Adhikari and A. Rico}, doi = {10.3847/1538-4357/ada4b3}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {38}, shortjournal = {The Astrophys. J.}, title = {Systematic search for long-term trends in fermi-LAT jetted active galactic nuclei}, volume = {980}, year = {2025}, }
• (2025). Asymmetries and circumstellar interaction in the type II SN 2024bch. ApJ, 980(1), 37. (www)

  @article{ , abstract = {We present a comprehensive multi-epoch photometric and spectroscopic study of SN 2024bch, a nearby (19.9 Mpc) Type II supernova (SN) with prominent early high-ionization emission lines. Optical spectra from 2.8 days after the estimated explosion reveal narrow lines of H i , He ii , C iv , and N iv that disappear by day 6. High-cadence photometry from the ground and Transiting Exoplanet Survey Satellite show that the SN brightened quickly and reached a peak M V ~ −17.8 mag within a week of explosion, and late-time photometry suggests a 56 Ni mass of 0.050 M ⊙ . High-resolution spectra from days 7.9 and 43 trace the unshocked circumstellar medium (CSM) and indicate a wind velocity of 30–40 km s −1 , a value consistent with a red supergiant (RSG) progenitor. Comparisons between models and the early spectra suggest a pre-SN mass-loss rate of \dot{M}\,\unicode{x0007E}\,1{0}^{-3}\unicode{8210}1{0}^{-2}\,{M}_{\odot }\,{\mathrm{yr}}^{-1} , which is too high to be explained by quiescent mass loss from RSGs, but is consistent with some recent measurements of similar SNe. Persistent blueshifted H i and [O i ] emission lines seen in the optical and near-IR spectra could be produced by asymmetries in the SN ejecta, while the multicomponent H α may indicate continued interaction with an asymmetric CSM well into the nebular phase. SN 2024bch provides another clue to the complex environments and mass-loss histories around massive stars.}, archive = {J_ApJ}, author = {Jennifer E. Andrews and Manisha Shrestha and K. Azalee Bostroem and Yize Dong and Jeniveve Pearson and M. M. Fausnaugh and David J. Sand and S. Valenti and Aravind P. Ravi and Emily Hoang and Griffin Hosseinzadeh and Ilya Ilyin and Daryl Janzen and M. J. Lundquist and Nicolás Meza and Nathan Smith and Saurabh W. Jha and Moira Andrews and Joseph Farah and Estefania Padilla Gonzalez and D. Andrew Howell and Curtis McCully and Megan Newsome and Craig Pellegrino and Giacomo Terreran and Patrick Wiggins and Brian Hsu and Collin T. Christy and Noah Franz and Xiaofeng Wang and Jialian Liu and Liyang Chen}, doi = {10.3847/1538-4357/ada555}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {37}, shortjournal = {The Astrophys. J.}, title = {Asymmetries and circumstellar interaction in the type II SN 2024bch}, volume = {980}, year = {2025}, }
• (2025). Little red dots: Rapidly growing black holes reddened by extended dusty flows. ApJ, 980(1), 36. (www)

  @article{ , abstract = {The James Webb Space Telescope (JWST) observations have revolutionized extragalactic research, particularly with the discovery of little red dots (LRDs), which have been discovered as a population of dust-reddened broad-line active galactic nuclei (AGNs). Their unique V-shaped spectral feature, characterized by a red optical continuum and a UV excess in the rest frame, challenges us to discern the relative contributions of the galaxy and AGN. We study a spectral energy distribution (SED) model for LRDs from rest-frame UV to infrared bands. We hypothesize that the incident radiation from an AGN, characterized by a typical SED, is embedded in an extended dusty medium with an extinction law similar to those seen in dense regions such as Orion Nebula or certain AGN environments. The UV−optical spectrum is described by dust-attenuated AGN emission, featuring a red optical continuum at λ > 4000 Å and a flat UV spectral shape established through a gray extinction curve at λ < 3000 Å, due to the absence of small-size grains. There is no need for additional stellar emission or AGN scattered light. In the infrared, the SED is shaped by an extended dust and gas distribution ( γ < 1; ρ ∝ r − γ ) with characteristic gas densities of ≃10–10 3 cm −3 , which allows relatively cool dust temperatures to dominate the radiation. As a result, these dust structures shift the emission energy peak from near-infrared to mid-infrared bands in the rest frame; for sources at z ~ 4–7, the corresponding wavelengths shift from the JWST/MIRI to Herschel range. This model, unlike the typical AGN hot torus models, can produce an infrared SED flattening that is consistent with LRD observations through JWST MIRI. Such a density structure can arise from the coexistence of inflows and outflows during the early assembly of galactic nuclei. This might be the reason why LRDs emerge preferentially in the high-redshift Universe younger than 1 billion years.}, archive = {J_ApJ}, author = {Zhengrong Li and Kohei Inayoshi and Kejian Chen and Kohei Ichikawa and Luis C. Ho}, doi = {10.3847/1538-4357/ada5fb}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {36}, shortjournal = {The Astrophys. J.}, title = {Little red dots: Rapidly growing black holes reddened by extended dusty flows}, volume = {980}, year = {2025}, }
• (2025). Autoencoder reconstruction of cosmological microlensing magnification maps. ApJ, 980(1), 35. (www)

  @article{ , abstract = {Enhanced modeling of microlensing variations in light curves of strongly lensed quasars improves measurements of cosmological time delays, the Hubble Constant, and quasar structure. Traditional methods for modeling extragalactic microlensing rely on computationally expensive magnification map generation. With large data sets expected from wide-field surveys like the Vera C. Rubin Legacy Survey of Space and Time, including thousands of lensed quasars and hundreds of multiply imaged supernovae, faster approaches become essential. We introduce a deep-learning model that is trained on pre-computed magnification maps covering the parameter space on a grid of κ , γ , and s . Our autoencoder creates a low-dimensional latent space representation of these maps, enabling efficient map generation. Quantifying the performance of magnification map generation from a low dimensional space is an essential step in the roadmap to develop neural network-based models that can replace traditional feed-forward simulation at much lower computational costs. We develop metrics to study various aspects of the autoencoder generated maps and show that the reconstruction is reliable. Even though we observe a mild loss of resolution in the generated maps, we find this effect to be smaller than the smoothing effect of convolving the original map with a source of a plausible size for its accretion disk in the red end of the optical spectrum and larger wavelengths and particularly one suitable for studying the broad-line region of quasars. Used to generate large samples of on-demand magnification maps, our model can enable fast modeling of microlensing variability in lensed quasars and supernovae.}, archive = {J_ApJ}, author = {Somayeh Khakpash and Federica B. Bianco and Georgios Vernardos and Gregory Dobler and Charles Keeton}, doi = {10.3847/1538-4357/ada5ff}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {35}, shortjournal = {The Astrophys. J.}, title = {Autoencoder reconstruction of cosmological microlensing magnification maps}, volume = {980}, year = {2025}, }
• (2025). Detectability of emission from exoplanet outflows calculated by pyTPCI, a new 1D radiation-hydrodynamic code. ApJ, 980(1), 34. (www)

  @article{ , abstract = {Photoevaporation in exoplanet atmospheres is thought to contribute to the shaping of the small planet radius valley. Escaping atmospheres have been detected in transmission across a variety of exoplanet types, from hot Jupiters to mini-Neptunes. However, no work has yet considered whether outflows might also be detectable in emission. We introduce pyTPCI, a new, open-source self-consistent 1D radiative-hydrodynamics code that is an improved version of The PLUTO-CLOUDY Interface. We use pyTPCI to model seven exoplanets (HD 189733b, HD 209458b, WASP-69b, WASP-107b, TOI-1430b, TOI-560b, and HAT-P-32b) at varying metallicities and compute their emission spectra to investigate their detectability across a variety of spectral lines. We calculate the eclipse depths and signal-to-noise ratios (SNRs) of these lines for a 10 m class telescope with a high-resolution spectrograph, taking into account appropriate line broadening mechanisms. We show that the most detectable spectral lines tend to be the 589 nm Na i doublet and the 1083 nm metastable helium triplet. H α and Mg i 457 nm are moderately strong for some planets at some metallicities, but they are almost always optically thin, so some of their emission may not be from the outflow. The planet with the highest-flux, highest-eclipse-depth, and highest-SNR lines is HD 189733b, with a Na i eclipse depth of 410 ppm and SNR of 2.4 per eclipse, and a He* eclipse depth of 170 ppm and SNR of 1.3. These signals would be marginally detectable with Keck if 3–10 eclipses were observed, assuming (over optimistically) photon limited observations.}, archive = {J_ApJ}, author = {Riley Rosener and Michael Zhang and Jacob L. Bean}, doi = {10.3847/1538-4357/ada6ab}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {34}, shortjournal = {The Astrophys. J.}, title = {Detectability of emission from exoplanet outflows calculated by pyTPCI, a new 1D radiation-hydrodynamic code}, volume = {980}, year = {2025}, }
• (2025). The sunburst arc with JWST. III. an abundance of direct chemical abundances. ApJ, 980(1), 33. (www)

  @article{ , abstract = {We measure the gas-phase abundances of the elements He, N, O, Ne, S, Ar, and Fe in an individual H ii region known to be leaking Lyman-continuum photons in the Sunburst Arc, a highly magnified galaxy at redshift z = 2.37. We detect the temperature-sensitive auroral lines [S ii ] λλ 4070, 4076, [O iii ] λ 4363, [S iii ] λ 6314, [O ii ] λλ 7320, 7330, and [Ne iii ] λ 3343 in a stacked spectrum of five multiple images of the Lyman-continuum emitter (LCE), from which we directly measure the electron temperature in the low-, intermediate-, and high-ionization zones. We also detect the density-sensitive doublets of [O ii ] λλ 3727, 3730, [S ii ] λλ 6718, 6733, and [Ar iv ] λλ 4713, 4741, which constrain the density in both the low- and high-ionization gas. With these temperature and density measurements, we measure gas-phase abundances with similar rigor as studies of local galaxies and H ii regions. We measure a gas-phase metallicity for the LCE of 12+\mathrm{log}({\rm{O}}/{\rm{H}})=7.97\pm 0.05 , and find an enhanced nitrogen abundance \mathrm{log}({\rm{N}}/{\rm{O}})=-0.6{5}_{-0.25}^{+0.16} . This nitrogen abundance is consistent with enrichment from a population of Wolf–Rayet stars, additional signatures of which are reported in a companion paper. Abundances of sulfur, argon, neon, and iron are consistent with local low-metallicity H ii regions and low-redshift galaxies. This study represents the most complete chemical abundance analysis of an individual H ii region at Cosmic Noon to date, which enables direct comparisons between local H ii regions and those in the distant Universe.}, archive = {J_ApJ}, author = {Brian Welch and T. Emil Rivera-Thorsen and Jane R. Rigby and Taylor A. Hutchison and Grace M. Olivier and Danielle A. Berg and Keren Sharon and Håkon Dahle and M. Riley Owens and Matthew B. Bayliss and Gourav Khullar and John Chisholm and Matthew Hayes and Keunho J. Kim}, doi = {10.3847/1538-4357/ada76c}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {33}, shortjournal = {The Astrophys. J.}, title = {The sunburst arc with JWST. III. an abundance of direct chemical abundances}, volume = {980}, year = {2025}, }
• (2025). The quest for a stable disk. ApJ, 980(1), 32. (www)

  @article{ , abstract = {The majority of disk galaxies manifest spirals and/or bars that are believed to result from dynamical instabilities. However, some galaxies have featureless disks, which are therefore inferred to be dynamically stable. Yet despite many years of effort, theorists have been unable to construct realistic models of galaxy disks that possess no instabilities and therefore could remain featureless. This conclusion has been reached through simulations for the most part, some of which have been confirmed by linear stability analyses. A. Toomre (1981) claimed that the Mestel disk, embedded in an equal-mass halo, is a notable counterexample, but his prediction of stability could not be reproduced in simulations, due to complicated nonlinear effects that caused secular growth of Poisson noise–driven disturbances until strong features emerged. Here, we revisit this issue and show that simply eliminating the most nearly circular orbits from Toomre's disk model can inhibit troublesome secular growth. We also present both 2D and 3D simulations of particle disks that remain featureless for over 50 orbit periods. We report that spiral evolution naturally depletes circular orbits and that the radial velocity distribution in the featureless disks of S0 galaxies should have negative kurtosis.}, archive = {J_ApJ}, author = {J. A. Sellwood and R. G. Carlberg}, doi = {10.3847/1538-4357/ada770}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {32}, shortjournal = {The Astrophys. J.}, title = {The quest for a stable disk}, volume = {980}, year = {2025}, }
• (2025). First results from the JWST early release science program Q3D: The fast outflow in a red quasar at z = 0.44. ApJ, 980(1), 31. (www)

  @article{ , abstract = {Quasar feedback may play a key role in the evolution of massive galaxies. The dust-reddened quasar F2M110648.35+480712 at z = 0.4352 is one of the few cases at its redshift that exhibits powerful quasar feedback through bipolar outflows. Our new observation with the integral field unit mode of the Near-infrared Spectrograph on board JWST opens a new window to examine this spectacular outflow through the Pa α emission line with ~3 × better spatial resolution than previous work. The morphology and kinematics of the Pa α nebula confirm the existence of a bipolar outflow extending on a scale of  ∼17 × 14 kpc and with a velocity reaching ∼1100 km s −1 . The higher spatial resolution of our new observation leads to more reliable measurements of outflow kinematics. Considering only the spatially resolved outflow and assuming an electron density of 100 cm −2 , the mass, momentum, and kinetic energy outflow rates are ∼50–210 M ⊙ yr −1 , ∼(0.3–1.7) × 10 36 dynes (∼14%–78% of the quasar photon momentum flux), and  ∼​​​​​​(0.16–1.27) × 10 44 erg s −1 (∼0.02%–0.20% of the quasar bolometric luminosity), respectively. The local instantaneous outflow rates generally decrease radially. We infer that the quasar is powerful enough to drive the outflow, while stellar processes cannot be overlooked as a contributing energy source. The mass outflow rate is ∼0.4–1.5 times the star formation rate, and the ratio of kinetic energy outflow rate to the quasar bolometric luminosity is comparable to the minimum value required for negative quasar feedback in simulations. This outflow may help regulate the star formation activity within the system to some extent.}, archive = {J_ApJ}, author = {Weizhe Liu and Sylvain Veilleux and Swetha Sankar and David S. N. Rupke and Nadia L. Zakamska and Dominika Wylezalek and Andrey Vayner and Caroline Bertemes and Yuzo Ishikawa and Yu-Ching Chen and Jenny E. Greene and Timothy Heckman and Guilin Liu and Hsiao-Wen Chen and Dieter Lutz and Sean D. Johnson and Nicole P. H. Nesvadba and Patrick Ogle and Nadiia Diachenko and Andy D. Goulding and Kevin N. Hainline and Fred Hamann and Hui Xian Grace Lim and Nora Lützgendorf and Vincenzo Mainieri and Ryan McCrory and Grey Murphree and Lu Shen and Eckhard Sturm and Lillian Whitesell}, doi = {10.3847/1538-4357/ada772}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {31}, shortjournal = {The Astrophys. J.}, title = {First results from the JWST early release science program Q3D: The fast outflow in a red quasar at z = 0.44}, volume = {980}, year = {2025}, }
• (2025). 3D nonequilibrium ionization and spectroscopic modeling of coronal mass ejections. i. comparison with Hinode/EIS observations. ApJ, 980(1), 30. (www)

  @article{ , abstract = {High-resolution EUV spectroscopy provides an informative diagnostic tool for the early evolution of coronal mass ejections (CMEs) since it can directly measure many physical properties of CME plasma close to the Sun that cannot be determined from white-light coronagraphs or narrowband imagers. The Hinode/EUV Imaging Spectrometer (EIS) captured a series of high-resolution EUV spectra of the 2008 April 9 event, also known as the "Cartwheel CME," during its initial acceleration period. CMEs are inherently dynamic events, driving the plasma from ionization equilibrium, which makes the nonequilibrium ionization (NEI) effects important when analyzing spectral observations. In this work, we performed simulations of the Cartwheel CME using the Alfvén Wave Solar atmosphere Model (AWSoM) to provide insight into the plasma structure and dynamics during the early evolution of this CME. For the first time, we combined self-consistent nonequilibrium charge state calculations in the EUV spectral line synthesis for a CME simulation to account for the plasma departures from ionization equilibrium everywhere in the CME. In this first paper of the series, we compare the simulation results to the EIS observations of this event to assess the quality of the AWSoM predictions. We find that the CME is out of equilibrium, indicating that NEI effects should be considered in the EUV spectral synthesis. Overall, the model reproduces the thermodynamic evolution of the CME in the low solar corona well, as compared to the EIS observations.}, archive = {J_ApJ}, author = {E. M. Wraback and E. Landi and W. B. Manchester and J. Szente}, doi = {10.3847/1538-4357/ada7e8}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {30}, shortjournal = {The Astrophys. J.}, title = {3D nonequilibrium ionization and spectroscopic modeling of coronal mass ejections. i. comparison with Hinode/EIS observations}, volume = {980}, year = {2025}, }
• (2025). Hybrid simulations of interstellar pickup ions at the solar wind termination shock revisited. ApJ, 980(1), 29. (www)

  @article{ , abstract = {We revisit previous hybrid simulations of the heating and acceleration of interstellar pickup ions (PUIs) at the solar wind termination shock. In previous simulations, a relatively cold initial distribution of PUIs was assumed; and while the resulting shock-heated distribution was consistent with Voyager 2 LECP measurements at about 30 keV, the intensity of the distribution downstream of the shock in the ~1–10 keV energy range was lower than predictions based on analysis of energetic neutral atoms (ENAs) from the Interstellar Boundary Explorer-Hi and Cassini's Ion and Neutral Camera. Here we perform new simulations with more realistic initial PUI distributions. We assume the distribution is a partially filled spherical shell in velocity space with a radius that varies from 320 to 640 km s −1 . We then use the distributions downstream of the shock from these new simulations to estimate the ENA flux spectrum and compare with observations. We find that the predicted ENA spectrum from the new simulations much better matches the observations over a broad range of energies. We conclude that the hybrid simulations provide reasonable predictions for the distribution of charged particles in the energy range from ~0.5 to 50 keV.}, archive = {J_ApJ}, author = {Joe Giacalone and M. Kornbleuth and M. Opher and M. Gkioulidou and J. Köta and E. Puzzoni and J. D. Richardson and G. P. Zank}, doi = {10.3847/1538-4357/ada89c}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {29}, shortjournal = {The Astrophys. J.}, title = {Hybrid simulations of interstellar pickup ions at the solar wind termination shock revisited}, volume = {980}, year = {2025}, }
• (2025). Tracking outflow using line locking (TOLL). II. large line-locking web identified in quasar j151352+085555. ApJ, 980(1), 28. (www)

  @article{ , abstract = {Quasar outflows often consist of two clouds with velocity separations matching the doublet spacings of common UV resonance transitions, a phenomenon known as line locking, which is commonly observed in quasar spectra. Multiple clouds can be locked together through multi-ion doublets, forming a "line-locking web." In the second paper of the TOLL project, we present the discovery of one of the largest "line-locking webs" known to date from the Very Large Telescope UVES spectra of QSO J151352+085555. We identify 12 associated narrow absorption line systems through the C iv , N v , Si iv , O vi , and multiple Lyman lines (Ly α to Ly ) and find 10 out of the 12 absorbers are line-locked together by comparing velocity separations between different absorption systems. By conducting photoionization modeling with CLOUDY, we measure the total hydrogen column densities, metallicities, and ionization parameters of these absorbers, which suggests that the absorbers likely have subsolar metallicities. A preliminary statistical analysis demonstrates that the shadowed clouds tend to have similar ionization states compared to the shadowing ones. Identification of one of the largest line-locking webs implies that radiative acceleration plays an important role in sorting out cloud velocities in quasar outflows and highlights the need for more sophisticated theoretical models to explain its formation and evolution.}, archive = {J_ApJ}, author = {Chen Chen and Zhicheng He and Weimin Yi and Tuo Ji and Marie Wingyee Lau and Bo Ma}, doi = {10.3847/1538-4357/ada933}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {28}, shortjournal = {The Astrophys. J.}, title = {Tracking outflow using line locking (TOLL). II. large line-locking web identified in quasar j151352+085555}, volume = {980}, year = {2025}, }
• (2025). Stellar X-ray variability and planetary evolution in the DS tucanae system. ApJ, 980(1), 27. (www)

  @article{ , abstract = {We present an analysis of four Chandra observations of the 45 Myr old DS Tuc binary system. We observed X-ray variability of both stars on timescales from hours to months, including two strong X-ray flares from star A. The implied flaring rates are in agreement with past observations made with XMM-Newton, though these rates remain imprecise due to the relatively short total observation time. We find a clear, monotonic decline in the quiescent level of the star by a factor of 1.8 across 8 months, suggesting stellar variability that might be due to an activity cycle. If proven through future observations, DS Tuc A would be the youngest star for which a coronal activity cycle has been confirmed. The variation in our flux measurements across the four visits is also consistent with the scatter in empirical stellar X-ray relationships with Rossby number. In simulations of the possible evolution of the currently super-Neptune-sized planet DS Tuc A b, we find a range of scenarios for the planet once it reaches a typical field age of 5 Gyr, from Neptune size down to a completely stripped super-Earth. Improved constraints on the planet's mass in the future would significantly narrow these possibilities. We advocate for further Chandra observations to better constrain the variability of this important system.}, archive = {J_ApJ}, author = {George W. King and Lía R. Corrales and Vincent Bourrier and Leonardo A. Dos Santos and Lauren Doyle and Baptiste Lavie and Gavin Ramsay and Peter J. Wheatley}, doi = {10.3847/1538-4357/ada948}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {27}, shortjournal = {The Astrophys. J.}, title = {Stellar X-ray variability and planetary evolution in the DS tucanae system}, volume = {980}, year = {2025}, }
• (2025). Retracing the cold plasma dispersion law in pulsar b0329+54: New insights into frequency-dependent dispersion measures. ApJ, 980(1), 26. (www)

  @article{ , abstract = {Multiple studies have investigated potential frequency-dependent dispersion measures (DMs) in PSR B0329+54, with sensitivities at levels of 10 −3 pc cm −3 or higher, using frequencies below 1 GHz. Utilizing the extensive bandwidth of the upgraded Giant Metrewave Radio Telescope, we conducted simultaneous observations of this pulsar across a frequency range of 300–1460 MHz. Our observations reveal a distinct point in the pulse profile of PSR B0329+54 that appears to align remarkably well with the cold-plasma dispersion law, resulting in a unique measured DM across the entire frequency range. In contrast, using times of arrival from widely adopted pulsar timing techniques (e.g., FFTFIT) leads to frequency-dependent DMs. We investigated the potential causes of these frequency-dependent DMs in this pulsar and their relationship with the underlying magnetic field geometry corresponding to the radio emission. Our study reveals that all frequencies in the range 300–1460 MHz originate from a region no larger than 204 km, and the dipolar magnetic-field geometry model indicates that the emission region is centered at ~800 km from the star. This is the tightest constraint on the size of the emission region reported so far for PSR B0329+54 at the given frequencies, and it is at least 5 times more stringent than the existing emission height constraints based on the dipolar geometry model.}, archive = {J_ApJ}, author = {Shyam S. Sharma and Tetsuya Hashimoto and Tomotsugu Goto and Shotaro Yamasaki and Simon C.-C. Ho}, doi = {10.3847/1538-4357/ada956}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {26}, shortjournal = {The Astrophys. J.}, title = {Retracing the cold plasma dispersion law in pulsar b0329+54: New insights into frequency-dependent dispersion measures}, volume = {980}, year = {2025}, }
• (2025). FEASTS: Radial distribution of h i surface densities down to 0.01 m⊙ pc−2 of 35 nearby galaxies. ApJ, 980(1), 25. (www)

  @article{ , abstract = {We present the H i surface density (Σ H i ) radial distributions based on total-power H i images obtained by FAST in the FEASTS program, for 35 galaxies with inclinations lower than 72°. We derive the H i radius R 001 , which is the radius for the 0.01 M ⊙ pc −2 (~10 18.1 cm −2 ) isodensity level, 100 times deeper than the 1 M ⊙ pc −2 level previously commonly used to measure R 1 . The profile shapes show a large diversity at a given radius in units of kpc, group virial radius, and R 1 , but they align more tightly with the radius normalized by R 001 . The universal H i profile has a scatter of ~0.2 dex and a scale length of ~0.11 R 001 in the outer region. We derive a new R 001 – M H i relation, which has a scatter of 0.03 dex and a similar slope of ~​​​​​​0.5 to the previously known R 1 – M H i relation. Excluding strongly tidal-interacting galaxies, the ratio R 001 / R 1 (anti)correlates strongly and significantly with the H i -to-stellar mass ratio and specific star formation rate, but not with the stellar mass, M H i , dark matter mass, or star formation rate. The strongly tidal-interacting galaxies tend to show deviations from these trends and have the most flattened profiles. These results imply that, in the absence of major tidal interactions, physical processes must cooperate so that Σ H i distributes in a self-similar way in the outer region down to the 0.01 M ⊙ pc −2 level. Moreover, they may drive gas flows in such a way that H i -richer galaxies have H i disks that not only extend further but also transport H i inward more efficiently from R 001 to R 1 .}, archive = {J_ApJ}, author = {Jing Wang and Dong Yang and Xuchen Lin and Qifeng Huang and Zhijie Qu and Hsiao-wen Chen and Hong Guo and Luis C. Ho and Peng Jiang and Zezhong Liang and Céline Péroux and Lister Staveley-Smith and Simon Weng}, doi = {10.3847/1538-4357/ada95a}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {25}, shortjournal = {The Astrophys. J.}, title = {FEASTS: Radial distribution of h i surface densities down to 0.01 m⊙ pc−2 of 35 nearby galaxies}, volume = {980}, year = {2025}, }
• (2025). Dark galactic subhalos and the gaia snail. ApJ, 980(1), 24. (www)

  @article{ , abstract = {Gaia has revealed a clear signal of disequilibrium in the solar neighborhood in the form of a spiral (or snail) feature in the vertical phase-space distribution. We investigate the possibility that this structure emerges from ongoing perturbations by dark \left(1{0}^{6}{M}_{\odot }-1{0}^{8}\,{M}_{\odot }\right) Galactic subhalos. We develop a probabilistic model for generating subhalo orbits based on a semianalytic model of structure formation, and combine this framework with an approximate prescription for calculating the response of the disk to external perturbations. We also develop a phenomenological treatment for the diffusion of phase-space spirals caused by gravitational scattering between stars and giant molecular clouds, a process that erases the kinematic signatures of old ( t ≳ 0.6 Gyr) events. Perturbations caused by dark subhalos are, on average, orders of magnitude weaker than those caused by luminous satellite galaxies, but the ubiquity of dark halos predicted by cold dark matter makes them a more probable source of strong perturbation to the dynamics of the solar neighborhood. Dark subhalos alone do not cause enough disturbance to explain the Gaia snail, but they excite fluctuations of ∼0.1–0.5 km s −1 in the mean vertical velocity of stars near the Galactic midplane that should persist to the present day. Subhalos also produce correlations between vertical frequency and orbital angle that could be mistaken as originating from a single past disturbance. Our results motivate investigation of the Milky Way's dark satellites by characterizing their kinematic signatures in phase-space spirals across the Galaxy.}, archive = {J_ApJ}, author = {Daniel Gilman and Jo Bovy and Neige Frankel and Andrew Benson}, doi = {10.3847/1538-4357/ada963}, journal = {The Astrophysical Journal}, month = {2}, number = {1}, pages = {24}, shortjournal = {The Astrophys. J.}, title = {Dark galactic subhalos and the gaia snail}, volume = {980}, year = {2025}, }
• (2025). A UV to X-ray view of soft excess in type 1 active galactic nuclei. i. sample selection and spectral profile. ApJ, 980(1), 23. (www)

  @article{ , abstract = {A core sample of 59 unobscured type 1 active galactic nuclei (AGNs) with simultaneous XMM-Newton X-ray and UV observations is compiled from the archives to probe the nature of soft X-ray excess (SE). In the first paper of this series, our focus centers on scrutinizing the spectral profile of the soft excess. Of the sources, ≈71% (42/59) exhibit power-law-like (po-like) soft excess, while ≈29% (17/59) exhibit blackbody-like (bb-like) soft excess. We show that a cutoff power law could uniformly characterize both types of soft excesses, with a median E cut of 1.40 keV for po-like and 0.14 keV for bb-like. For the first time, we report a robust and quantitative correlation between the SE profile and SE strength (the ratio of SE luminosity to that of the primary power-law continuum in 0.5–2.0 keV), indicating that stronger soft excess is more likely to be po-like, or effectively has a higher E cut . This correlation cannot be explained by ionized disk reflection alone, which produces mostly bb-like soft excess ( E cut ~ 0.1 keV) as revealed by relxilllp simulation. Remarkably, we show with simulations that a toy hybrid scenario, where both ionized disk reflection ( relxilllp , with all reflection parameters fixed at default values except for ionization of the disk) and warm corona ( compTT , with temperature fixed at 1 keV) contribute to the observed soft excess, can successfully reproduce the observed correlation. This highlights the ubiquitous hybrid nature of the SE in AGNs, and underscores the importance of considering both components while fitting the spectra of soft excess.}, archive = {J_ApJ}, author = {Shi-Jiang Chen and Jun-Xian Wang and Jia-Lai Kang and Wen-Yong Kang and Hao Sou and Teng Liu and Zhen-Yi Cai and Zhen-Bo Su}, doi = {10.3847/1538-4357/ada035}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {23}, shortjournal = {The Astrophys. J.}, title = {A UV to X-ray view of soft excess in type 1 active galactic nuclei. i. sample selection and spectral profile}, volume = {980}, year = {2025}, }
• (2025). Bulge oscillation driven by outflows of active galactic nuclei. i. fast outflow case. ApJ, 980(1), 22. (www)

  @article{ , abstract = {There is growing evidence for star formation inside outflows of active galactic nuclei (AGNs). The formed stars are injected into bulges and give rise to perturbation of bulges. In this paper, we investigate the issues of nonrotating, spherically symmetric bulges under the perturbation of fast, massive outflows with stars formed inside. We show that the potential perturbation of outflows, together with injection and dynamical friction of these stars, could drive bulge oscillations. Still, we find that nonzero radial velocity of bulges will be driven by the episodic outflows of AGNs, and after the AGN has quenched, the radial velocity will tend to zero within a timescale ~ τ AGN , which is the AGN's lifetime. For some typical values of bulges and AGNs, we find that the expansion and contraction velocities are a few × 10 km s −1 for 10 10 M ⊙ bulges and mass outflowing rate 500 M ⊙ yr −1 , which would give observational signatures.}, archive = {J_ApJ}, author = {Yue-Chang Peng and Jian-Min Wang and Yu Zhao and Luis C. Ho}, doi = {10.3847/1538-4357/ada275}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {22}, shortjournal = {The Astrophys. J.}, title = {Bulge oscillation driven by outflows of active galactic nuclei. i. fast outflow case}, volume = {980}, year = {2025}, }
• (2025). Improving the determination of supernova cosmological redshifts by using galaxy groups. ApJ, 980(1), 21. (www)

  @article{ , abstract = {At the low-redshift end ( z < 0.05) of the Hubble diagram with Type Ia Supernovae (SNe Ia), the contribution to Hubble residual scatter from peculiar velocities (PVs) is of similar size to that due to the limitations of the standardization of the SN Ia light curves. A way to improve the redshift measurement of the SN host galaxy is to utilize the average redshift of the galaxy group, effectively averaging over small-scale/intracluster PVs. One limiting factor is the fraction of SN host galaxies in galaxy groups, previously found to be 30% using (relatively incomplete) magnitude-limited galaxy catalogs. Here, we do the first analysis of N -body simulations to predict this fraction, finding ∼73% should have associated groups and group averaging should improve redshift precision by ∼135 km s −1 (∼0.04 mag at z = 0.025). Furthermore, using spectroscopic data from the Anglo-Australian Telescope, we present results from the first pilot program to evaluate whether or not 23 previously unassociated SN Ia hosts belong in groups. We find that 91% of these candidates can be associated with groups, consistent with predictions from simulations given the sample size. Combining with previously assigned SN host galaxies in Pantheon+, we demonstrate improvement in Hubble residual scatter equivalent to 145 km s −1 , also consistent with simulations. For new and upcoming low- z samples from, for example, the Zwicky Transient Facility and the Legacy Survey of Space and Time, a separate follow-up program identifying galaxy groups of SN hosts is a highly cost-effective way to enhance their constraining power.}, archive = {J_ApJ}, author = {Erik R. Peterson and Bastien Carreres and Anthony Carr and Daniel Scolnic and Ava Bailey and Tamara M. Davis and Dillon Brout and Cullan Howlett and David O. Jones and Adam G. Riess and Khaled Said and Georgie Taylor}, doi = {10.3847/1538-4357/ada285}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {21}, shortjournal = {The Astrophys. J.}, title = {Improving the determination of supernova cosmological redshifts by using galaxy groups}, volume = {980}, year = {2025}, }
• (2025). Pushing the atacama large millimeter/submillimeter array to the limit: 140 pc resolution observations of a z = 6.6 Quasar–Galaxy merger resolve strikingly different morphologies of dust continuum and [C ii] 158 μm emission. ApJ, 980(1), 20. (www)

  @article{ , abstract = {We present 0\mathop{.}\limits^{^{\prime\prime} }026 (140 pc) resolution Atacama Large Millimeter/submillimeter Array observations of [C ii ] 158 μ m and dust continuum emission of the z = 6.6 quasar J0305–3150, resolved over ~​​​​​​300–400 independent resolution elements. The dust continuum emission is compact with ~80% recovered within r\lt 0\mathop{.}\limits^{^{\prime\prime} }3 (1.6 kpc), whereas the [C ii ] emission profile is composed of a central Gaussian ( r\lt 0\mathop{.}\limits^{^{\prime\prime} }4 , i.e., <2.2 kpc) and an extended component (detected up to ~10 kpc at >3 σ ). We infer a direct contribution of the quasar to the observed 260 GHz continuum S ν ,QSO / S ν ,QSO + Host ≲ 1%. We report the detection of far-infrared (FIR)-detected star-forming clumps with r < 200 pc and properties similar to that of rest-frame UV–optical clumps reported in the literature. The 200 pc resolved [C ii ]/FIR ratio follows the global relation with the FIR surface brightness established in low- and high-redshift galaxies, even at the quasar location. We find that dust continuum is emitted in regions of \unicode{x0007E}0^{\prime\prime} \,.02-0^{\prime\prime} \,.04 consistent with the size of photodissociation regions (PDRs), whereas 50% of the [C ii ] originates from larger physical scales ( θ ≳ 2''). The large-scale [C ii ] emission presents a velocity gradient aligned with a nearby companion with perturbed kinematics, and misaligned with the kinematics of the small-scale emission. The absence of significant [C ii ] emission by structures with physical scale ≲ 1 kpc implies that [C ii ] emission is not produced in dense PDRs located at the boundary of giant molecular clouds. We argue instead that [C ii ] is produced in low-density PDRs in the interstellar medium and diffuse H i gas tidally stripped during the ongoing merger.}, archive = {J_ApJ}, author = {Romain A. Meyer and Bram Venemans and Marcel Neeleman and Roberto Decarli and Fabian Walter}, doi = {10.3847/1538-4357/ada351}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {20}, shortjournal = {The Astrophys. J.}, title = {Pushing the atacama large millimeter/submillimeter array to the limit: 140 pc resolution observations of a z = 6.6 Quasar–Galaxy merger resolve strikingly different morphologies of dust continuum and [C ii] 158 μm emission}, volume = {980}, year = {2025}, }
• (2025). Revisiting the flaring activity in early 2015 of BL lacertae object s5 0716+714. ApJ, 980(1), 19. (www)

  @article{ , abstract = {In this work, we analyzed multiwavelength data of the BL Lac object S5 0716+714 to investigate its emission mechanisms during a flaring state observed in early 2015. We examined the temporal behavior and broadband spectral energy distributions (SEDs) during the flare. The size of the γ -ray emission region was estimated based on the variability timescale. To explore the multiwavelength properties of S5 0716+714, we employed three one-zone models: the synchrotron self-Compton (SSC) model, the SSC plus external Compton (EC) model, and the SSC plus pp interactions model, to reproduce the SEDs. Our findings indicate that, while the SSC model can describe the SEDs, it requires an extreme Doppler factor. In contrast, the SSC plus EC model successfully fits the SEDs under the assumption of weak external photon fields but requires a high Doppler factor. Additionally, the SSC plus pp interactions model also reproduces the SEDs, with γ -ray emission originating from π 0 decay. However, this model leads to a jet power that exceeds the Eddington luminosity, which remains plausible due to the flaring state or the presence of a highly collimated jet.}, archive = {J_ApJ}, author = {Zhihao Ouyang and Hubing Xiao and Marina Manganaro and Shangchun Xie and Jingyu Wu and Jianzhen Chen and Rui Xue and Gege Wang and Shaohua Zhang and Junhui Fan}, doi = {10.3847/1538-4357/ada3bc}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {19}, shortjournal = {The Astrophys. J.}, title = {Revisiting the flaring activity in early 2015 of BL lacertae object s5 0716+714}, volume = {980}, year = {2025}, }
• (2025). The eruptive duality of a filament on 2023 april 21. ApJ, 980(1), 18. (www)

  @article{ , abstract = {Here we study a filament eruption on 2023 April 21. The filament was composed of two segments, named S1 and S2. Initially, the brightening and bidirectionally plasmoid flows appeared inside S1, and then the west part of S1 (WS1) experienced rapid rising and eruption, accompanied by coronal dimming, flare ribbons, and a secondary flare ribbon. However, the east part of S1 (ES1) rose slowly and was confined. The material within ES1 drained back to its eastern footpoint, resulting in the footpoint brightening. In the later phase, the south footpoint of the stable extreme-ultraviolet (EUV) loops overlying ES1 was brightened also, which may result from the disturbance of drainage. During S1 eruption and activation, S2 remained stable. Nonlinear force-free field extrapolation shows that the footpoints of the magnetic field lines overlying WS1 are rooted on the flare ribbons, while the field lines overlying ES1, which share a negative field with other lines, correspond to the stable EUV loops. Based on potential field extrapolation, we calculate the decay index of the background fields overlying the filament. It indicates that the critical height of the torus instability of the fields overlying WS1 is lower than that overlying ES1. To interpret this filament eruption, we first put forward the eruptive duality, characterized by the eruption of the partial filament structure and the confinement of the other structure, and this duality is determined by the properties of the overlying fields.}, archive = {J_ApJ}, author = {Yue Fang and Jun Zhang}, doi = {10.3847/1538-4357/ada5f3}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {18}, shortjournal = {The Astrophys. J.}, title = {The eruptive duality of a filament on 2023 april 21}, volume = {980}, year = {2025}, }
• (2025). Contribution of unresolved sources to diffuse gamma-ray emission from the galactic plane. ApJ, 980(1), 17. (www)

  @article{ , abstract = {The diffuse gamma-ray emission from the Milky Way serves as a crucial probe for understanding the propagation and interactions of cosmic rays within our Galaxy. The Galactic diffuse gamma-ray emission between 10 TeV and 1 PeV has been recently measured by the square kilometer array (KM2A) of the Large High Altitude Air Shower Observatory (LHAASO). The flux is higher than predicted for cosmic rays interacting with the interstellar medium. In this work, we utilize a nonparametric method to derive the source count distribution using the published first LHAASO source catalog. Based on this distribution, we calculate the contribution of unresolved sources to the diffuse emission measured by KM2A. When comparing our results to the measured diffuse gamma-ray emission, we demonstrate that for the outer Galactic region, the contributions from unresolved sources and those predicted by models are roughly consistent with the observations within the uncertainties. However, for the inner Galactic region, additional components are required to account for the observed data.}, archive = {J_ApJ}, author = {Jiayin He and Houdun Zeng and Yi Zhang and Qiang Yuan and Rui Zhang and Jun Li}, doi = {10.3847/1538-4357/ada6b2}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {17}, shortjournal = {The Astrophys. J.}, title = {Contribution of unresolved sources to diffuse gamma-ray emission from the galactic plane}, volume = {980}, year = {2025}, }
• (2025). Coordinated velocity shift of multiple c iv and si iv broad absorption lines in quasar SDSS j113048.45+225206.6. ApJ, 980(1), 16. (www)

  @article{ , abstract = {We present an analysis of the coordinated velocity shifts observed in multiple C iv and Si iv broad absorption lines (BALs) in the quasar SDSS J113048.45+225206.6. The quasar exhibits an extensive BAL system spanning a velocity range of approximately 13,000 km s −1 , which can be further delineated into five absorption systems (A1 to A5). Our analysis revealed coordinated velocity shifts in the C iv BALs of systems A1 and A2 and in the Si iv BALs of systems A2 and A3. These shifts were accompanied by coordinated variations in equivalent widths, which can be attributed to changes in the ionization state of the clouds in response to fluctuations in the ionizing continuum. By comparing the absorption line systems, we deduced that the velocity-shifted systems (A1 to A3) are located closer to the central engine, possess higher velocities, and are in a higher ionization state compared to the nonshifted systems (A4 to A5). These characteristics suggest that the outflow producing the velocity-shifted systems is situated in a more extreme environment and is more severely impacted by background radiation energy than the nonshifted systems. Furthermore, the synchronization of these velocity shifts across multiple components suggests a common underlying mechanism. Consequently, we infer that the coordinated velocity-shift signatures may indicate actual deceleration of the outflow clouds, driven by radiation pressure from the background light source.}, archive = {J_ApJ}, author = {Wei-Jian Lu and Ying-Ru Lin}, doi = {10.3847/1538-4357/adaa7e}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {16}, shortjournal = {The Astrophys. J.}, title = {Coordinated velocity shift of multiple c iv and si iv broad absorption lines in quasar SDSS j113048.45+225206.6}, volume = {980}, year = {2025}, }
• (2025). Vertical shear instability in thermally stratified protoplanetary disks. II. hydrodynamic simulations and observability. ApJ, 980(1), 15. (www)

  @article{ , abstract = {We conduct 3D hydrodynamic simulations to investigate the nonlinear outcomes and observability of vertical shear instability (VSI) in protoplanetary disks. Our models include both vertically isothermal and thermally stratified disks, with the latter representing realistic conditions featuring a hotter atmosphere above the midplane. We find that the VSI grows more rapidly and becomes stronger in thermally stratified disks due to enhanced shear, resulting in higher levels of turbulence. At saturation, the turbulence stress reaches α Rϕ ≳ 10 −3 , more than 1 order of magnitude stronger than the isothermal case. The saturated turbulence is more pronounced near the disk surfaces than at the midplane. On synthetic velocity residual maps, obtained by subtracting the Keplerian rotational velocity, perturbations driven by the VSI manifest as axisymmetric rings in isothermal disks and as ring segments in thermally stratified disks. The latter are visible at disk inclinations as high as 45° in thermally stratified disks. The amplitudes of these residual velocities range from ∼50 to ∼100 m s −1 at a 20° inclination, with larger values corresponding to greater thermal stratification. The magnitude of the observed velocity residual increases with the optical depth of the tracer used, as optically thick lines probe the regions near the disk surfaces.}, archive = {J_ApJ}, author = {Han-Gyeol Yun and Woong-Tae Kim and Jaehan Bae and Cheongho Han}, doi = {10.3847/1538-4357/ad9f42}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {15}, shortjournal = {The Astrophys. J.}, title = {Vertical shear instability in thermally stratified protoplanetary disks. II. hydrodynamic simulations and observability}, volume = {980}, year = {2025}, }
• (2025). Vertical shear instability in thermally stratified protoplanetary disks. i. a linear stability analysis. ApJ, 980(1), 14. (www)

  @article{ , abstract = {Vertical shear instability (VSI), driven by a vertical gradient of rotational angular velocity, is a promising source of turbulence in protoplanetary disks. We examine the semiglobal stability of thermally stratified disks and find that the VSI consists of surface and body modes: surface modes are confined to regions of strong shear, while body modes extend perturbations across the disk, consistent with the previous findings. In thermally stratified disks, surface modes bifurcate into two branches. The branch associated with the strongest shear at mid-height exhibits a higher growth rate compared to the branch near the surfaces. Surface modes generally grow rapidly and require a high radial wavenumber k R , whereas body mode growth rates increase as k R decreases. Thermal stratification enhances the growth rates of both surface and body modes and boosts VSI-driven radial kinetic energy relative to vertical energy. Our results suggest that simulations will initially favor surface modes with large k R , followed by an increase in body modes with smaller k R , with faster progression in more thermal stratified disks.}, archive = {J_ApJ}, author = {Han-Gyeol Yun and Woong-Tae Kim and Jaehan Bae and Cheongho Han}, doi = {10.3847/1538-4357/ad9f41}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {14}, shortjournal = {The Astrophys. J.}, title = {Vertical shear instability in thermally stratified protoplanetary disks. i. a linear stability analysis}, volume = {980}, year = {2025}, }
• (2025). Rare occasions: Tidal disruption events rarely power the AGNs observed in dwarf galaxies. ApJ, 980(1), 13. (www)

  @article{ , abstract = {Tidal disruption events (TDEs) could be an important growth channel for massive black holes in dwarf galaxies. Theoretical work suggests that the observed active galactic nuclei (AGNs) in dwarf galaxies are predominantly TDE-powered. To assess this claim, we perform variability analyses on the dwarf-hosted AGNs detected in the 7 Ms Chandra Deep Field-South survey, with observations spanning ≈16 yr. Based on the spectral energy distribution modeling with x-cigale , we select AGNs hosted by dwarf galaxies (stellar mass below 10 10 M ⊙ ). We focus on X-ray sources with full-band detections, leading to a sample of 78 AGNs (0.122 ≤ z ≤ 3.515). We fit the X-ray light curves with a canonical TDE model of t −5/3 and a constant model. If the former outperforms the latter in fitting quality for a source, we consider the source as a potential TDE. We identify five potential TDEs, constituting a small fraction of our sample. Using true- and false-positive rates obtained from fitting models to simulated light curves, we perform Bayesian analysis to obtain the posterior of the TDE fraction for our sample. The posterior peaks close to zero (2.56%), and we obtain a 2 σ upper limit of 9.80%. Therefore, our result indicates that the observed AGNs in dwarf galaxies are not predominantly powered by TDEs.}, archive = {J_ApJ}, author = {Joanne Tan and Guang Yang and Jonelle L. Walsh and W. N. Brandt and Bin Luo and Franz E. Bauer and Chien-Ting Chen and Mouyuan Sun and Yongquan Xue}, doi = {10.3847/1538-4357/ad8341}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {13}, shortjournal = {The Astrophys. J.}, title = {Rare occasions: Tidal disruption events rarely power the AGNs observed in dwarf galaxies}, volume = {980}, year = {2025}, }
• (2025). A SPectroscopic survey of biased halos in the reionization era (ASPIRE): Spectroscopically complete census of obscured cosmic star formation rate density at z = 4–6. ApJ, 980(1), 12. (www)

  @article{ , abstract = {We present a stringent measurement of the dust-obscured star formation rate density (SFRD) at z = 4–6 from the ASPIRE JWST Cycle-1 medium and ALMA Cycle-9 large program. We obtained JWST/NIRCam grism spectroscopy and ALMA 1.2 mm continuum map along 25 independent quasar sightlines, covering a total survey area of  ∼35 arcmin 2 where we search for dusty star-forming galaxies (DSFGs) at z = 0–7. We identify eight DSFGs in seven fields at z = 4–6 through the detection of H α or [O iii ] λ 5008 lines, including fainter lines such as H β , [O iii ] λ 4960, [N ii ] λ 6585, and [S ii ] λλ 6718,6733 for six sources. With this spectroscopically complete DSFG sample at z = 4–6 and negligible impact from cosmic variance (shot noise), we measure the infrared luminosity function (IRLF) down to L IR ∼ 2 × 10 11 L ⊙ . We find flattening of IRLF at z = 4–6 towards the faint end (power-law slope \alpha =0.5{9}_{-0.45}^{+0.39} ). We determine the dust-obscured cosmic SFRD at this epoch to be \mathrm{log}[{\rho }_{\mathrm{SFR},\mathrm{IR}}/({M}_{\odot }\,{\mathrm{yr}}^{-1}\,{\mathrm{Mpc}}^{-3})]=-1.5{2}_{-0.13}^{+0.14} . This is significantly higher than previous determinations using ALMA data in the Hubble Ultra Deep Field, which is void of DSFGs at z = 4–6 because of strong cosmic variance (shot noise). We conclude that the majority (66% ± 7%) of cosmic star formation at z ∼ 5 is still obscured by dust. We also discuss the uncertainty of SFRD propagated from far-IR spectral energy distribution and IRLF at the bright end, which will need to be resolved with future ALMA and JWST observations.}, archive = {J_ApJ}, author = {Fengwu Sun and Feige Wang and Jinyi Yang and Jaclyn B. Champagne and Roberto Decarli and Xiaohui Fan and Eduardo Bañados and Zheng Cai and Luis Colina and Eiichi Egami and Joseph F. Hennawi and Xiangyu Jin and Hyunsung D. Jun and Yana Khusanova and Mingyu Li and Zihao Li and Xiaojing Lin and Weizhe Liu and Romain A. Meyer and Maria A. Pudoka and George H. Rieke and Yue Shen and Wei Leong Tee and Bram Venemans and Fabian Walter and Yunjing Wu and Huanian Zhang and Siwei Zou}, doi = {10.3847/1538-4357/ad9d0e}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {12}, shortjournal = {The Astrophys. J.}, title = {A SPectroscopic survey of biased halos in the reionization era (ASPIRE): Spectroscopically complete census of obscured cosmic star formation rate density at z = 4–6}, volume = {980}, year = {2025}, }
• (2025). UNCOVER: The rest-ultraviolet to near-infrared multiwavelength structures and dust distributions of submillimeter-detected galaxies in a2744. ApJ, 980(1), 11. (www)

  @article{ , abstract = {With the wavelength coverage, sensitivity, and high spatial resolution of JWST, it is now possible to peer through the dust attenuation to probe the rest-frame near-infrared (NIR) and stellar structures of extremely dusty galaxies at cosmic noon ( z ∼ 1−3). In this paper we leverage the combined Atacama Large Millimeter/submillimeter Array (ALMA) and JWST/Hubble Space Telescope coverage in A2744 to study the multiwavelength (0.5−4.4 μ m) structures of 11 submillimeter detected galaxies at z ∼ 0.9−3.5 that are fainter than bright "classical" submillimeter galaxies, seven of which are detected in deep X-ray data. While these objects reveal a diversity of structures and sizes, all are smaller and more concentrated toward longer wavelengths. Of the X-ray-detected objects, only two show evidence for appreciable active galactic nucleus (AGN) flux contributions (at ≳2 μ m). Excluding the two AGN-dominated objects, the smaller long-wavelength sizes indicate that their rest-frame NIR light profiles, inferred to trace their stellar mass profiles, are more compact than their optical profiles. The submillimeter detections and visible dust lanes suggest that centrally concentrated dust is a key driver of the observed color gradients. Further, we find that more concentrated galaxies tend to have lower size ratios (rest-frame NIR to optical); this suggests that the galaxies with the most compact light distributions also have the most concentrated dust. The 1.2 mm flux densities and size ratios of these nine objects suggest that both total dust quantity and geometry impact these galaxies' multiwavelength structures. Upcoming higher-resolution 1.2 mm ALMA imaging will facilitate joint spatially resolved analysis and will directly test the dust distributions within this representative submillimeter population.}, archive = {J_ApJ}, author = {Sedona H. Price and Katherine A. Suess and Christina C. Williams and Rachel Bezanson and Gourav Khullar and Erica J. Nelson and Bingjie Wang and John R. Weaver and Seiji Fujimoto and Vasily Kokorev and Jenny E. Greene and Gabriel Brammer and Sam E. Cutler and Pratika Dayal and Lukas J. Furtak and Ivo Labbe and Joel Leja and Tim B. Miller and Themiya Nanayakkara and Richard Pan and Katherine E. Whitaker}, doi = {10.3847/1538-4357/ada0b1}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {11}, shortjournal = {The Astrophys. J.}, title = {UNCOVER: The rest-ultraviolet to near-infrared multiwavelength structures and dust distributions of submillimeter-detected galaxies in a2744}, volume = {980}, year = {2025}, }
• (2025). Simulating high-redshift galaxies: Enhancing UV luminosity with star formation efficiency and a top-heavy IMF. ApJ, 980(1), 10. (www)

  @article{ , abstract = {Recent findings from photometric and spectroscopic JWST surveys have identified examples of high-redshift galaxies at z ≳ 10. These high- z galaxies appear to form much earlier and exhibit greater UV luminosity than predicted by theoretical work. In this study, our goal is to reproduce the brightness of these sources by simulating high-redshift galaxies with virial masses M vir = 10 9 –10 10 M ⊙ at z > 10. To achieve this, we conduct cosmological hydrodynamic zoom-in simulations, modifying baryonic subgrid physics, and post-process our simulation results to confirm the observability of our simulated galaxies. Specifically, we enhanced star formation activity in high-redshift galaxies by either increasing the star formation efficiency up to 100% or adopting a top-heavy initial mass function (IMF). Our simulation results indicate that both increasing star formation efficiency and adopting a top-heavy IMF play crucial roles in boosting the UV luminosity of high-redshift galaxies, potentially exceeding the limiting magnitude of JWST surveys in earlier epochs. In particular, the episodic starburst resulting from enhanced star formation efficiency may explain the high-redshift galaxies observed by JWST, as it evacuates dust from star-forming regions, making the galaxies more observable. We demonstrate this correlation between star formation activity and dust mass evolution within the simulated galaxies. Also, adopting a top-heavy IMF could enhance observability due to an overabundance of massive stars, although it may also facilitate rapid metal enrichment. Using our simulation results, we derive several observables such as effective radius, UV slope, and emission-line rates, which could serve as valuable theoretical estimates for comparison with existing spectroscopic results and forthcoming data from the JWST NIRSpec and MIRI instruments.}, archive = {J_ApJ}, author = {Tae Bong Jeong and Myoungwon Jeon and Hyunmi Song and Volker Bromm}, doi = {10.3847/1538-4357/ada27d}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {10}, shortjournal = {The Astrophys. J.}, title = {Simulating high-redshift galaxies: Enhancing UV luminosity with star formation efficiency and a top-heavy IMF}, volume = {980}, year = {2025}, }
• (2025). Similarities and differences between ICME-driven shocks observed by VEX (∼0.72 au) and WIND (∼1.0 au). ApJ, 980(1), 9. (www)

  @article{ , abstract = {The features of interplanetary shocks driven by interplanetary coronal mass ejections (ICMEs) observed by WIND (∼1.0 au) and Venus Express (VEX; ∼0.72 au) during the same period are statistically analyzed by comparing their similarities and differences. It is found that the proportion of ICME-driven shocks in all shocks decreases slightly from ∼0.72 to ∼1 au. The yearly occurrence of ICME-driven shocks at both ∼0.72 and ∼1 au roughly follows the sunspot cycle, while the magnetic field ratio does not show such a correspondence. In each year, the annual medians of the shock angle for ICME-driven shocks at ∼1 au are consistently larger than those at ∼0.72 au, and the annual medians of the magnetic field ratio for events at ∼1 au are slightly smaller than those at ∼0.72 au. Planar magnetic structures (PMSs) downstream of ICME-driven shocks are also analyzed. Approximately 28.57% of the detected PMS events from VEX observations and 28.84% from WIND observations cover the entire 2 hr intervals downstream of the shocks, which are referred to as full PMS events. Through comparative analysis for VEX and WIND observations, it is found that strong and quasi-perpendicular ICME-driven shocks are the most preferable conditions for full PMS formation.}, archive = {J_ApJ}, author = {Mengsi Ruan and Pingbing Zuo and Zilu Zhou and Jiayun Wei and Xueshang Feng and Yi Wang and Qi Xu and Xiaojun Xu and Zhengyang Zou and Zhenning Shen}, doi = {10.3847/1538-4357/ada35b}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {9}, shortjournal = {The Astrophys. J.}, title = {Similarities and differences between ICME-driven shocks observed by VEX (∼0.72 au) and WIND (∼1.0 au)}, volume = {980}, year = {2025}, }
• (2025). Characteristics of the IBEX ribbon and their implications for a source region outside the heliopause. ApJ, 980(1), 8. (www)

  @article{ , abstract = {This paper presents a comprehensive exploration of the Interstellar Boundary Explorer energetic neutral atom (ENA) ribbon, focusing on its spatial and temporal variations over 14 yr. Methodological advancements, including a refined map modeling procedure and a new ribbon separation technique with appropriate error propagation, enable a detailed investigation of the ribbon's features. Utilizing statistically robust metrics, this study reveals details of the ribbon across energy and time. Key findings include energy- and time-dependent variations in flux, angular radius, ribbon profile width, and higher moments. By applying these metrics, we reveal new complexity to the evolution of the ribbon over time, highlighting the nuanced relationship between it and the solar wind. Furthermore, the study examines for the first time the ribbon as it passes through the starboard/heliotail region (Lon EC 120°–180°), revealing properties distinct from other portions of the ribbon. The analysis uncovers an anticorrelation between ribbon width and flux, which provides quantitative support for a multisource ribbon created by a combination of solar wind neutrals that generate a spatiall narrow ribbon component and heliosheath neutrals giving rise to a broad component. Finally, differences in the temporal evolution of the ENA flux at different energies provide additional support that the location of the ribbon source region is beyond the heliopause.}, archive = {J_ApJ}, author = {Sung Jun Noh and Daniel B. Reisenfeld and Lauren J. Beesley and Yue Chen and Fan Guo and Herbert O. Funsten and Paul H. Janzen and Thomas K. Kim and Asher Merrill and Dave Osthus and Nehpreet K. Walia and Eric J. Zirnstein}, doi = {10.3847/1538-4357/ada36a}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {8}, shortjournal = {The Astrophys. J.}, title = {Characteristics of the IBEX ribbon and their implications for a source region outside the heliopause}, volume = {980}, year = {2025}, }
• (2025). Mach number scaling of foreshock magnetic fluctuations at quasi-parallel bow shocks and their role in magnetospheric driving throughout the solar system. ApJ, 980(1), 7. (www)

  @article{ , abstract = {Upstream of quasi-parallel bow shocks, reflected ions generate ion–ion instabilities. The resulting magnetic fluctuations can advect through the shock and interact with planetary magnetospheres. The amplitude of magnetic fluctuations depends on the strength of the shock, quantified by the Alfvén Mach number ( M A ), which is the ratio of solar wind velocity to the local Alfvén velocity. With increasing heliocentric distance, the solar wind M A generally increases, such that Mercury typically experiences a lower M A ∼ 5 compared to Earth ( M A ∼ 8), and Mars a slightly higher M A ∼ 9. Farther out in the solar system, Saturn has even higher M A (∼10). However, the solar wind flow is highly irregular, and on top of solar cycle variations these values for average M A at each planet do not capture extreme events. Statistical analysis of OMNIWeb observations from 2015 to 2023 shows that sustained (30 minutes or more) high M A (30–100) occurs at Earth about once a month. Using a selection of events in the ion foreshock regions of Mercury, Earth, Mars, and Saturn, a linear scaling is calculated for the maximum magnetic fluctuation amplitude as a function of M A . The resulting slope is ∼0.2. Based on the dominant fluctuation frequency for the largest-amplitude events at each planet, it is found that Mars exists in a special regime where the wave period of the magnetic fluctuations can be similar to or longer than the magnetospheric convection timescale, making Mars more susceptible to space weather effects associated with foreshock fluctuations.}, archive = {J_ApJ}, author = {Brandon L. Burkholder and Li-Jen Chen and Katariina Nykyri and Norberto Romanelli and Menelaos Sarantos and Dave Sibeck and Jaye Verniero and Gina A. DiBraccio and Daniel Gershman and Martin Lindberg and Erin Kincade}, doi = {10.3847/1538-4357/ada440}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {7}, shortjournal = {The Astrophys. J.}, title = {Mach number scaling of foreshock magnetic fluctuations at quasi-parallel bow shocks and their role in magnetospheric driving throughout the solar system}, volume = {980}, year = {2025}, }
• (2025). The influence of general relativity on the spins of celestial bodies in inclined orbits. ApJ, 980(1), 6. (www)

  @article{ , abstract = {Through the Rossiter–McLaughlin effect, several hot Jupiters have been found to exhibit spin–orbit misalignment and even retrograde orbits. The high obliquity observed in these planets can be attributed to two primary formation mechanisms, as summarized in the existing literature. First, the host star's spin becomes misaligned with the planetary disk during the late stages of star formation, primarily due to chaotic accretion and magnetic interactions between the star and the planetary disk. Second, the orbital inclination of an individual planet can be excited by dynamical processes such as planet–planet scattering, the Lidov–Kozai cycle, and secular chaos within the framework of Newtonian mechanics. This study introduces a third mechanism, where, within the framework of general relativity, the post-Newtonian spin–orbit coupling term induces precession of the host star's spin around the orbital angular momentum. The orbital inclination, relative to a reference plane, can expand the range of deviation in the spatial orientation of the bodies' spins from the plane's normal. The varying amplitude and period of spin precession for both the star and the planet are derived theoretically, and the results, which can be applied without restriction, agree well with numerical simulations.}, archive = {J_ApJ}, author = {Huan-Rong Yuan and Ying Wang and Xin Wu and Ji-Wei Xie and Hui-Gen Liu and Ji-Lin Zhou and Wei Sun}, doi = {10.3847/1538-4357/ada5fc}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {6}, shortjournal = {The Astrophys. J.}, title = {The influence of general relativity on the spins of celestial bodies in inclined orbits}, volume = {980}, year = {2025}, }
• (2025). Observations of the ultraviolet-bright star III-60 in the globular cluster NGC 6723. ApJ, 980(1), 5. (www)

  @article{ , abstract = {We have analyzed archival far-ultraviolet spectra of the UV-bright star III-60 in the globular cluster NGC 6723 obtained with the Far Ultraviolet Spectroscopic Explorer and the Cosmic Origins Spectrograph. We find that the star's photospheric parameters (effective temperature T eff = 44,800 ± 1200 K, surface gravity \mathrm{log}g=4.89\pm 0.18 , and helium abundance \mathrm{log}N({\rm{He}})/N({\rm{H}})=-0.84\pm 0.29 ) are consistent with the values derived from its optical spectrum, suggesting that optically derived values are generally accurate for evolved stars with T eff ≲ 50,000 K. Relative to the cluster's red giant branch stars, III-60 is enhanced in nitrogen and depleted in carbon and oxygen. The star exhibits strong P Cygni profiles in both components of the N v λ 1240 doublet, but the resonance lines of other species show no evidence of a stellar wind. The star's effective temperature and luminosity place it on the evolutionary tracks of stars evolving from the blue horizontal branch, but its high mass (∼1.2 M ⊙ ) indicates that it is the product of a stellar merger. Its helium, carbon, and nitrogen abundances suggest that it is following an evolutionary path similar to that of the low-carbon, intermediate helium-rich hot subdwarfs.}, archive = {J_ApJ}, author = {William V. Dixon}, doi = {10.3847/1538-4357/ada604}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {5}, shortjournal = {The Astrophys. J.}, title = {Observations of the ultraviolet-bright star III-60 in the globular cluster NGC 6723}, volume = {980}, year = {2025}, }
• (2025). A 22 yr cycle of the network topology of solar active regions. ApJ, 980(1), 4. (www)

  @article{ , abstract = {In this paper, solar cycles 21–24 were compared using complex network analysis. A network was constructed for these four solar cycles to facilitate the comparison. In these networks, the nodes represent the active regions of the Sun that emit flares, and the connections correspond to the sequence of solar flares over time. This resulted in a directed network with self-connections allowed. The model proposed by Abe and Suzuki for earthquake networks was followed. The incoming degree for each node was calculated, and the degree distribution was analyzed. It was found that for each solar cycle, the degree distribution follows a power law, indicating that solar flares tend to appear in correlated active zones rather than being evenly distributed. Additionally, a variation in the characteristic exponent γ for each cycle was observed, with higher values in even cycles compared to odd cycles. A more detailed analysis was performed by constructing 11 yr networks and shifting them in 1 yr intervals. This revealed that the characteristic exponent shows a period of approximately 22 yr coincident with the Hale cycle, suggesting that the complex networks provide information about the solar magnetic activity.}, archive = {J_ApJ}, author = {Eduardo Flández and Alejandro Zamorano and Víctor Muñoz}, doi = {10.3847/1538-4357/ada60e}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {4}, shortjournal = {The Astrophys. J.}, title = {A 22 yr cycle of the network topology of solar active regions}, volume = {980}, year = {2025}, }
• (2025). Rotating neutron stars with relativistic ab initio calculations. ApJ, 980(1), 3. (www)

  @article{ , abstract = {The equation of state (EOS) of extremely dense matter is crucial for understanding the properties of rotating neutron stars. Starting from the widely used realistic Bonn potentials rooted in a relativistic framework, we derive EOSs by performing state-of-the-art relativistic Brueckner–Hartree–Fock calculations in the full Dirac space. The self-consistent and simultaneous consideration of both positive- and negative-energy states (NESs) of the Dirac equation allows us to avoid the uncertainties present in calculations where NESs are treated using approximations. To manifest the impact of rotational dynamics, several structural properties of neutron stars across a wide range of rotation frequencies and up to the Keplerian limit are obtained, including the gravitational and baryonic masses, the polar and equatorial radii, and the moments of inertia. Our theoretical predictions align well with the latest astrophysical constraints from observations of massive neutron stars and joint mass–radius measurements. The maximum mass for rotating configurations can reach up to 2.93 M ⊙ for Bonn A potential, while the radius of a 1.4 M ⊙ neutron star in the nonrotating case can be extended to around 17 km through constant baryonic mass sequences. Relations with good universalities between the Keplerian frequency and static mass as well as radius are obtained, from which the radius of the black widow PSR J0952-0607 is predicted to be less than 19.58 km. Furthermore, to understand how rotation deforms the equilibrium shape of a neutron star, the eccentricity is also calculated. The approximate universality between the eccentricity at the Keplerian frequency and the gravitational mass is found.}, archive = {J_ApJ}, author = {Xiaoying Qu and Sibo Wang and Hui Tong}, doi = {10.3847/1538-4357/ada76b}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {3}, shortjournal = {The Astrophys. J.}, title = {Rotating neutron stars with relativistic ab initio calculations}, volume = {980}, year = {2025}, }
• (2025). Resonant damping and instability of propagating magnetohydrodynamic body modes in a flux tube with shear flow under photospheric conditions. ApJ, 980(1), 2. (www)

  @article{ , abstract = {The influence of shear flow on resonant absorption is theoretically investigated for propagating magnetohydrodynamic body modes in cusp (slow) and Alfvén continua in a cylindrical flux tube under photospheric conditions. An analytical dispersion relation for resonant absorption in the presence of flow shear is developed by assuming a thin boundary layer. The numerical solutions reveal that the presence of flow shear has a rather negative impact on the resonant absorption of the body mode compared to the surface modes. As the flow shear increases, it first slightly increases the strength of resonant absorption for the forward body modes and then decreases it below the strength of no flow shear case for both resonances. It is also found that as the flow shear increases, the range of the axial wavenumber and wave frequency for the cusp resonance decreases when the wave frequency is close to the upper boundary of the cusp continuum. For the backward body modes, the strength of the resonance absorption decreases with the increment of the flow shear. When the flow shear is sufficiently large, the waves propagate in the forward direction, and their amplitude grows with a small increment.}, archive = {J_ApJ}, author = {D. J. Yu}, doi = {10.3847/1538-4357/ada7f7}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {2}, shortjournal = {The Astrophys. J.}, title = {Resonant damping and instability of propagating magnetohydrodynamic body modes in a flux tube with shear flow under photospheric conditions}, volume = {980}, year = {2025}, }
• (2025). Propagating bright knots in the chromospheric fibrils. ApJ, 980(1), 1. (www)

  @article{ , abstract = {The solar chromosphere is a crucial layer for resolving the problem of atmospheric heating. There are many bright features, which are considered as the thermal signals for heating the atmosphere, and these features are suggested to have resulted from either magnetic reconnection or wave dissipation. It has been reported that a large number of propagating bright knots are detected in the chromosphere and corona. In this paper, we employ the high-resolution chromospheric H α data from the New Vacuum Solar Telescope to study the propagating bright knots. As the propagating bright knots move along the chromospheric fibrils, we select isolated and clear fibrils and track the knots along these fibrils. While the number of knots in a fibril region is equal to or greater than 5, the fibril and the knots are recorded. Based on the data on 2019 September 4, we detected 98 knots, and these knots move along 13 fibrils. On 2019 November 2, 87 knots, which move along 12 fibrils, were recorded. These propagating bright knots have an average area of around 0.8 Mm 2 , with propagating distances from 190 to 2450 km, propagating velocities from 5 to 51 km s −1 , and an average lifetime of 71 s. To examine the relationship between the knots and the photospheric magnetic fields, we measure the field underneath these knots. The average magnetic flux densities are less than 10 Gauss, comparable with the noise level. We suggest that these knots are not produced by magnetic reconnection, but rather by wave dissipation.}, archive = {J_ApJ}, author = {Shaoxuan Tong and Jun Zhang and Tao Ding}, doi = {10.3847/1538-4357/ada7fa}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {1}, shortjournal = {The Astrophys. J.}, title = {Propagating bright knots in the chromospheric fibrils}, volume = {980}, year = {2025}, }
• (2025). The JADES transient survey: Discovery and classification of supernovae in the JADES deep field. ApJ, 979(2), 250. (www)

  @article{ , abstract = {The JWST Advanced Deep Extragalactic Survey (JADES) is a multicycle JWST program that has taken among the deepest near- and mid-infrared images to date (down to ∼30 AB mag) over ∼25 arcmin 2 in the GOODS-S field in two sets of observations with 1 yr of separation. This presented the first opportunity to systematically search for transients, mostly supernovae (SNe), out to z > 2. We found 79 SNe: 38 at z < 2, 23 at 2 < z < 3, 8 at 3 < z < 4, 7 at 4 < z < 5, and 3 with undetermined redshifts, where the redshifts are predominantly based on spectroscopic or highly reliable JADES photometric redshifts of the host galaxies. At this depth, the detection rate is ∼1–2 arcmin –2 yr –1 , demonstrating the power of JWST as an SN discovery machine. We also conducted multiband follow-up NIRCam observations of a subset of the SNe to better constrain their light curves and classify their types. Here, we present the survey, sample, search parameters, spectral energy distributions, light curves, and classifications. Even at z ≥ 2, the NIRCam data quality is high enough to allow SN classification via multiepoch light-curve fitting with confidence. The multiepoch SN sample includes a Type Ia SN at z spec = 2.90, a Type IIP SN at z spec = 3.61, and a Type Ic-BL SN at z spec = 2.83. We also found that two z ∼ 16 galaxy candidates from the first imaging epoch were actually transients that faded in the second epoch, illustrating the possibility that moderate/high-redshift SNe could mimic high-redshift dropout galaxies.}, archive = {J_ApJ}, author = {Christa DeCoursey and Eiichi Egami and Justin D. R. Pierel and Fengwu Sun and Armin Rest and David A. Coulter and Michael Engesser and Matthew R. Siebert and Kevin N. Hainline and Benjamin D. Johnson and Andrew J. Bunker and Phillip A. Cargile and Stephane Charlot and Wenlei Chen and Mirko Curti and Shea DeFour-Remy and Daniel J. Eisenstein and Ori D. Fox and Suvi Gezari and Sebastian Gomez and Jacob Jencson and Bhavin A. Joshi and Sanvi Khairnar and Jianwei Lyu and Roberto Maiolino and Takashi J. Moriya and Robert M. Quimby and George H. Rieke and Marcia J. Rieke and Brant Robertson and Melissa Shahbandeh and Louis-Gregory Strolger and Sandro Tacchella and Qinan Wang and Christina C. Williams and Christopher N. A. Willmer and Chris Willott and Yossef Zenati}, doi = {10.3847/1538-4357/ad8fab}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {250}, shortjournal = {The Astrophys. J.}, title = {The JADES transient survey: Discovery and classification of supernovae in the JADES deep field}, volume = {979}, year = {2025}, }
• (2025). Carbon and iron deficiencies in quiescent galaxies at z = 1–3 from JWST-SUSPENSE: Implications for the formation histories of massive galaxies. ApJ, 979(2), 249. (www)

  @article{ , abstract = {We present the stellar metallicities and multielement abundances (C, Mg, Si, Ca, Ti, Cr, and Fe) of 15 massive (log M / M ⊙ = 10.2–11.2) quiescent galaxies at z = 1–3, derived from ultradeep JWST-SUSPENSE spectra. Compared to quiescent galaxies at z ∼ 0, these galaxies exhibit a deficiency of 0.26 ± 0.04 dex in [C/H], 0.16 ± 0.03 dex in [Fe/H], and 0.07 ± 0.04 dex in [Mg/H], implying rapid formation and quenching before significant enrichment from asymptotic giant branch stars and Type Ia supernovae. Additionally, we find that galaxies forming at higher redshift consistently show higher [Mg/Fe] and lower [Fe/H] and [Mg/H], regardless of their observed redshift. The evolution in [Fe/H] and [C/H] is therefore primarily driven by lower-redshift samples naturally including galaxies with longer star formation timescales. In contrast, the lower [Mg/H] likely reflects earlier-forming galaxies expelling larger gas reservoirs during their quenching phase. Consequently, the mass–metallicity relation, primarily reflecting [Mg/H], is somewhat lower at z = 1–3 compared to the lower-redshift relation. Finally, we compare our results to standard stellar population modeling approaches employing solar abundance patterns and nonparametric star formation histories (using Prospector ). Our simple stellar population (SSP)-equivalent ages agree with the mass-weighted ages from Prospector , while the metallicities disagree significantly. Nonetheless, the metallicities better reflect [Fe/H] than total [ Z /H]. We also find that the star formation timescales inferred from elemental abundances are significantly shorter than those from Prospector , and we discuss the resulting implications for the early formation of massive galaxies.}, archive = {J_ApJ}, author = {Aliza G. Beverage and Martje Slob and Mariska Kriek and Charlie Conroy and Guillermo Barro and Rachel Bezanson and Gabriel Brammer and Chloe M. Cheng and Anna de Graaff and Natascha M. Förster Schreiber and Marijn Franx and Brian Lorenz and Pavel E. Mancera Piña and Danilo Marchesini and Adam Muzzin and Andrew B. Newman and Sedona H. Price and Alice E. Shapley and Mauro Stefanon and Katherine A. Suess and Pieter van Dokkum and David Weinberg and Daniel R. Weisz}, doi = {10.3847/1538-4357/ad96b6}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {249}, shortjournal = {The Astrophys. J.}, title = {Carbon and iron deficiencies in quiescent galaxies at z = 1–3 from JWST-SUSPENSE: Implications for the formation histories of massive galaxies}, volume = {979}, year = {2025}, }
• (2025). H-AMR FORGE’d in FIRE. i. magnetic state transitions, jet launching, and radiative emission in super-eddington, highly magnetized quasar disks formed from cosmological initial conditions. ApJ, 979(2), 248. (www)

  @article{ , abstract = {Quasars are powered by supermassive black hole (SMBH) accretion disks, yet standard thin disk models are inconsistent with many observations. Recently, P. F. Hopkins et al. simulated the formation of a quasar disk feeding an SMBH of mass M = 1.3 × 10 7 M ⊙ in a galaxy. The disk had surprisingly strong toroidal magnetic fields that supported it vertically from gravity and powered rapid accretion. What feedback can such a system produce? To answer this, we must follow the gas to the event horizon. For this, we interpolated the quasar into the general-relativistic radiation magnetohydrodynamics code H-AMR and performed 3D simulations with BH spins a = 0 and a = 0.9375. This remapping generates magnetic monopoles, which we erase using a novel divergence cleaning approach. Despite the toroidal magnetic field's dominance at large radii, vertical magnetic flux builds up near the event horizon, leading to a magnetic state transition within the inner 200 gravitational radii of the disk. This powers strong winds and, for spinning BHs, relativistic jets that can spin down the BH within 5−10 Myr. Sometimes, vertical magnetic fields of opposite polarity reach the BH, causing a polarity inversion event that briefly destroys the jets and, possibly, the X-ray corona. These strong fields power accretion at rates 5 × the Eddington limit, which can double the BH mass in 5–10 Myr. When a = 0.9375 ( a = 0), the energy in mechanical outflows and radiation equals about 60% (10%) and 100% (3%) of the accreted rest mass energy, respectively. Much of the light escapes in cool, ≳1300 au photospheres, consistent with quasar microlensing and spectral energy distributions.}, archive = {J_ApJ}, author = {Nicholas Kaaz and Matthew Liska and Alexander Tchekhovskoy and Philip F. Hopkins and Jonatan Jacquemin-Ide}, doi = {10.3847/1538-4357/ad9a86}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {248}, shortjournal = {The Astrophys. J.}, title = {H-AMR FORGE’d in FIRE. i. magnetic state transitions, jet launching, and radiative emission in super-eddington, highly magnetized quasar disks formed from cosmological initial conditions}, volume = {979}, year = {2025}, }
• (2025). Spectroscopic confirmation of a massive protocluster with two substructures at z ≃ 3.1. ApJ, 979(2), 247. (www)

  @article{ , abstract = {We present the results of a Keck and Northern Extended Millimeter Array spectroscopic survey of 507 galaxies, where we confirm the presence of two massive overdensities at z = 3.090−3.110 and z = 3.133−3.155 in the neighborhood of the GOODS-N, each with over a dozen spectroscopically confirmed members. We find that both of these have galaxy overdensities of near-infrared-detected galaxies of δ gal,obs = 6−9 within corrected volumes of (6−7) × 10 3 cMpc 3 . We estimate the properties of the z = 0 descendants of these overdensities using a spherical collapse model and find that both should virialize by z ≃ 0.5−0.8, with total masses of M tot ≃ (6−7) × 10 14 M ⊙ . The same spherical collapse calculations, as well as a clustering-of-clusters statistical analysis, suggest a >80% likelihood that the two overdensities will collapse into a single cluster with M tot = (1.0−1.5) × 10 15 M ⊙ by z ~ 0.1−0.4. The z = 3.14 substructure contains a core of four bright dusty star-forming galaxies with ΣSFR = 2700 ± 700 M ⊙ yr −1 in a volume of only 280 cMpc 3 .}, archive = {J_ApJ}, author = {Michael J. Nicandro Rosenthal and Amy J. Barger and Lennox L. Cowie and Logan H. Jones and Stephen J. McKay and Anthony J. Taylor}, doi = {10.3847/1538-4357/ad9c67}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {247}, shortjournal = {The Astrophys. J.}, title = {Spectroscopic confirmation of a massive protocluster with two substructures at z ≃ 3.1}, volume = {979}, year = {2025}, }
• (2025). Fast-rotating A- and F-type stars with hα emissions in NGC 3532: Candidate UV-dim stars?. ApJ, 979(2), 246. (www)

  @article{ , abstract = {Extended main-sequence stars that are dim in the ultraviolet passbands of the Hubble Space Telescope (UV-dim stars) are found in several young and intermediate-age star clusters in the Magellanic Clouds (MCs). The obscuring of the dust in the disks of stars expelled as a result of fast rotation has been suggested to be responsible for the appearance of UV-dim stars and to play an important role in the formation of extended main sequences. In this paper, we report a population of A- and F-type stars that show H α emission features in their spectra in the young (~340 Myr old) neighboring Galactic star cluster NGC 3532. By fitting the observed absorption profiles, we found that most H α emitters are fast-rotating stars, indicating that they form decretion disks by fast rotation like Be stars. As A- and F-type stars dominate the extended main-sequence turnoff regions of intermediate-age clusters, their appearance provides observational evidence to support the dust extinction scenario for these clusters, and they might be the counterparts of UV-dim stars that are detected in remote MC star clusters such as NGC 1783.}, archive = {J_ApJ}, author = {Chenyu He and Chengyuan Li and Gang Li}, doi = {10.3847/1538-4357/ad9de3}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {246}, shortjournal = {The Astrophys. J.}, title = {Fast-rotating A- and F-type stars with hα emissions in NGC 3532: Candidate UV-dim stars?}, volume = {979}, year = {2025}, }
• (2025). A semi-analytical model for stellar evolution in AGN disks. ApJ, 979(2), 245. (www)

  @article{ , abstract = {Disks of gas accreting onto supermassive black holes may host numerous stellar-mass objects, formed within the disk or captured from a nuclear star cluster. We present a simplified model of stellar evolution in these dense environments, which exhibits exceptional agreement with full stellar evolution calculations at a minuscule fraction of the cost. Although the model presented here is limited to stars burning hydrogen in their cores, it is sufficient to determine the evolutionary fate of disk-embedded stars: whether they proceed to later stages of nuclear burning and leave behind a compact remnant, reach a quasi-steady state where mass loss and accretion balance one another, or whether accretion proceeds faster than stellar structure can adjust, causing a runaway. We highlight how various disk parameters and phenomena such as gap opening affect stellar evolution outcomes. We also highlight how our model can accommodate time-varying conditions, such as those experienced by a star on an eccentric orbit, and can couple to N -body integrations. This model will enable more detailed studies of stellar populations and their interaction with accretion disks than have previously been possible.}, archive = {J_ApJ}, author = {Alexander J. Dittmann and Matteo Cantiello}, doi = {10.3847/1538-4357/ad9e92}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {245}, shortjournal = {The Astrophys. J.}, title = {A semi-analytical model for stellar evolution in AGN disks}, volume = {979}, year = {2025}, }
• (2025). Vortex-induced rings and gaps within protoplanetary disks. ApJ, 979(2), 244. (www)

  @article{ , abstract = {Observations of protoplanetary disks have revealed the presence of both crescent-shaped and ring-like structures in dust continuum emission. These crescents are thought to arise from dust-trapping vortices generated by the Rossby wave instability, which induces density waves akin to those caused by planets. These vortices have the potential to create gaps and rings within the disk, resulting from the dissipation of their density waves. We carry out 2D hydrodynamic simulations in the shearing box to investigate vortex–disk interaction. We find that long-lived vortices can produce dust rings and gaps in inviscid discs detectable by the Atacama Large Millimeter/submillimeter Array, and a more elongated vortex produces rings at larger separations. Vortex-induced density waves carry over 2 orders of magnitude higher angular momentum flux compared to planet-induced ones that shock at the same location, making the former much more effective at producing dust gaps and rings far away.}, archive = {J_ApJ}, author = {Xiaoyi Ma and Pinghui Huang and Cong Yu and Ruobing Dong}, doi = {10.3847/1538-4357/ad9f2c}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {244}, shortjournal = {The Astrophys. J.}, title = {Vortex-induced rings and gaps within protoplanetary disks}, volume = {979}, year = {2025}, }
• (2025). Jupiter evolutionary models incorporating stably stratified regions. ApJ, 979(2), 243. (www)

  @article{ , abstract = {We address the issue of which broad set of initial conditions for the planet Jupiter best matches the current presence of a "fuzzy core" of heavy elements, while at the same time comporting with measured parameters such as its effective temperature, atmospheric helium abundance, radius, and atmospheric metallicity. Our focus is on the class of fuzzy cores that can survive convective mixing to the present day and on the unique challenges of an inhomogeneous Jupiter with stably stratified regions now demanded by the Juno gravity data. Hence, using the new code APPLE , we attempt to put a nonadiabatic Jupiter into an evolutionary context. This requires not only a mass density model, the major relevant byproduct of the Juno data, but a thermal model that is subject to interior heat transport, a realistic atmospheric flux boundary, a helium rain algorithm, and the latest equation of state. The result is a good fit to most major thermal, compositional, and structural constraints that still preserve a fuzzy core and that should inform future more detailed models of the current Jupiter in the context of its evolution from birth.}, archive = {J_ApJ}, author = {Roberto Tejada Arevalo and Ankan Sur and Yubo Su and Adam Burrows}, doi = {10.3847/1538-4357/ada030}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {243}, shortjournal = {The Astrophys. J.}, title = {Jupiter evolutionary models incorporating stably stratified regions}, volume = {979}, year = {2025}, }
• (2025). Unraveling the dusty environment around RT vir. ApJ, 979(2), 242. (www)

  @article{ , abstract = {Infrared (IR) studies of asymptotic giant branch (AGB) stars are critical to our understanding of the formation of cosmic dust. In this investigation, we explore the mid- to far-IR emission of the oxygen-rich AGB star RT Virginis. This optically thin dusty environment has unusual spectral features when compared to other stars in its class. To explore this enigmatic object we use the one-dimensional radiative transfer modeling code DUSTY. Modeled spectra are compared with observations from the Infrared Space Observatory, InfraRed Astronomical Satellite, the Herschel Space Observatory, and a host of other sources to determine the properties of RT Vir's circumstellar material. Our models suggest a set of two distant and cool dust shells at low optical depths ( τ V ,inner = 0.16, τ V ,outer = 0.06), with inner dust temperatures T 1 = 330 K, T 3 = 94 K. Overall, these dust shells exhibit a chemical composition consistent with dust typically found around O-rich AGB stars. However, the distribution of materials differs significantly. The inner shell consists of a mixture of silicates, Al 2 O 3 , FeO, and Fe, while the outer shell primarily contains crystalline Al 2 O 3 polymorphs. This chemical change is indicative of two distinct epochs of dust formation around RT Vir. These changes in dust composition are driven by either changes in the pressure–temperature conditions around the star or by a decrease in the C/O ratio due to hot-bottom burning.}, archive = {J_ApJ}, author = {Michael D. Preston and Angela K. Speck and Sean Dillon and B. Sargent}, doi = {10.3847/1538-4357/ada0bb}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {242}, shortjournal = {The Astrophys. J.}, title = {Unraveling the dusty environment around RT vir}, volume = {979}, year = {2025}, }
• (2025). A dichotomy in the 1–24 GHz parsec-scale radio spectra of radio-quiet quasars. ApJ, 979(2), 241. (www)

  @article{ , abstract = {We present the parsec-scale radio spectra of a representative sample of 13 Palomar–Green radio-quiet quasars, based on our new Very Long Baseline Array (VLBA) observations at 8.4 and 23.6 GHz and our earlier VLBA studies at 1.5 and 5.0 GHz. The radio core emission generally exhibits a flat spectrum at 1.5–5.0 GHz, which indicates a compact optically thick synchrotron source on a scale smaller than the broad-line region (BLR) radius R BLR ∼ 0.01–0.1 pc. The 8.4–23.6 GHz spectral slope remains flat in four objects indicating the inner radius of the radio source R in < 0.1 R BLR , and becomes steep in four other objects indicating R in ∼ 0.5 R BLR . The flat 8.4–23.6 GHz slope sources may be associated with a continuous ejection starting at the accretion disk corona. The steep 8.4–23.6 GHz slope sources may be produced by an interaction of an active-galactic-nucleus-driven wind with the BLR gas or a low-power jet extending to the BLR scale. Seven of these eight objects, which have a flat or steep 8.4–23.6 GHz slope, reside at the Eddington ratios L / L Edd < 0.3, and four of the remaining five objects, where the 8.4–23.6 GHz fluxes are too faint to significantly constrain the slope, reside at L / L Edd > 0.3. The 8.4–23.6 GHz radio emission in the high- L / L Edd objects may be weak due to more extended emission from a radiation-pressure-driven wind. Future submillimeter observations can further constrain the inward radial extent of the radio emission down to the coronal scale.}, archive = {J_ApJ}, author = {Sina Chen and Ari Laor and Ehud Behar and Ranieri D. Baldi and Joseph D. Gelfand and Amy E. Kimball}, doi = {10.3847/1538-4357/ada142}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {241}, shortjournal = {The Astrophys. J.}, title = {A dichotomy in the 1–24 GHz parsec-scale radio spectra of radio-quiet quasars}, volume = {979}, year = {2025}, }
• (2025). HCG 57: Evidence for shock-heated intergalactic gas from X-rays and optical emission line spectroscopy. ApJ, 979(2), 240. (www)

  @article{ , abstract = {We present Chandra and XMM-Newton X-ray observations of the compact group HCG 57, and optical integral field spectroscopy of the interacting galaxy pair HCG 57A/D. These two spiral galaxies recently suffered an off-axis collision with HCG 57D passing through the disk of A. We find evidence of a gas bridge linking the galaxies, containing ∼10 8 M ⊙ of hot, ∼1 keV thermal plasma and warm ionized gas radiating in H α , H β , [O iii ] and [N ii ] lines. The optical emission lines in the central regions of HCG 57D show excitation properties consistent with H ii -regions, while the outer rim of HCG 57D parts of the bridge and the outer regions of HCG 57A show evidence of shocked gas consistent with shock velocities of 200–300 km s −1 . In contrast, the X-ray emitting gas requires a collision velocity of 650–750 km s −1 to explain the observed temperatures. These different shock velocities can be reconciled by considering the contributions of rotation to collision velocity in different parts of the disks, and the clumpy nature of the preshock medium in the galaxies, which likely lead to different shock velocities in different components of the turbulent postshocked gas. We examine the diffuse X-ray emission in the group members and their associated point sources, identifying X-ray active galactic nuclei in HCG 57A, B, and D. We also confirm the previously reported ∼1 keV intra-group medium and find it to be relaxed with a low central entropy (18.0 ± 1.7 keV cm 2 within 20 kpc) but a long cooling time (5.9 ± 0.8 Gyr).}, archive = {J_ApJ}, author = {Ewan O’Sullivan and P. N. Appleton and B. A. Joshi and Lauranne Lanz and Katherine Alatalo and Jan M. Vrtilek and Andreas Zezas and Laurence P. David}, doi = {10.3847/1538-4357/ada14b}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {240}, shortjournal = {The Astrophys. J.}, title = {HCG 57: Evidence for shock-heated intergalactic gas from X-rays and optical emission line spectroscopy}, volume = {979}, year = {2025}, }
• (2025). Detection of enhanced germanium in a new cool extreme helium star a980: Insights and implications. ApJ, 979(2), 239. (www)

  @article{ , abstract = {A fine abundance analysis of a recently discovered hydrogen-deficient carbon (HdC) star, A980, is presented. Based on the observed high-resolution optical spectrum, we ascertain that A980 is a cool extreme helium (EHe) star and not an HdC star. Singly ionized germanium Ge ii lines are identified in A980's optical spectrum. These are the first-ever detections of germanium lines in an EHe star's observed spectrum and provide the first measurements of germanium abundance in an EHe star. The overabundance of germanium in A980's atmosphere provides us with evidence for the synthesis of germanium in EHe stars. Among the known cool EHe stars, A980 exhibits a maximum enhancement of the s -process elements based on a significant number of transitions. The measured elemental abundances reveal signs of H-burning, He-burning, and specifically the nucleosyntheses of the key elements Ge, Sr, Y, Zr, and Ba. The nucleosyntheses of these key elements are discussed in light of asymptotic giant branch evolution and the expectation from the accretion of an He white dwarf by a C–O white dwarf or by a neutron star.}, archive = {J_ApJ}, author = {Ajay Kumar Saini and Gajendra Pandey}, doi = {10.3847/1538-4357/ada1c2}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {239}, shortjournal = {The Astrophys. J.}, title = {Detection of enhanced germanium in a new cool extreme helium star a980: Insights and implications}, volume = {979}, year = {2025}, }
• (2025). Exploring the evolution of a dwarf spheroidal galaxy with SPH simulations. II. AGN feedback. ApJ, 979(2), 238. (www)

  @article{ , abstract = {We investigate active galactic nucleus (AGN) feedback from an intermediate-mass black hole at the center of a dwarf spheroidal galaxy, by performing isolated galaxy simulations using a modified version of the GADGET-3 code. We consider Leo II (PGC 34176) in the Local Group as our simulation reference model. Beginning with black hole seeds ranging from 10 3 −10 6 M ⊙ , our simulations focus on comparing stellar/SN-only feedback with AGN+stellar/SN feedback over 13.7 Gyr of galactic evolution. Our results indicate that a low-mass AGN in a dwarf galaxy influences the star formation history under specific physical conditions. While AGN feedback is generally negative on star formation, instances of positive feedback were also identified. Despite measurable effects on the evolution of the dwarf host galaxy, black hole seeds exhibited only marginal growth. We tested several physical scenarios as modified models in our simulations, primarily concerning the dynamics of the central black holes, which may wander within dwarf galaxies rather than being centrally located. However, none of these adjustments significantly impacted the growth of the black hole seeds. This suggests that intermediate-mass black holes may struggle to achieve higher masses in isolated environments, with mergers and interactions likely playing crucial roles in their growth. Nevertheless, AGN feedback exhibited nonnegligible effects in our simulated dwarf spheroidal galaxies, despite the assumed dominant role of stellar feedback in the low-mass regime.}, archive = {J_ApJ}, author = {Roberto Hazenfratz and Paramita Barai and Gustavo A. Lanfranchi and Anderson Caproni}, doi = {10.3847/1538-4357/ada1d1}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {238}, shortjournal = {The Astrophys. J.}, title = {Exploring the evolution of a dwarf spheroidal galaxy with SPH simulations. II. AGN feedback}, volume = {979}, year = {2025}, }
• (2025). Black hole accretion and spin-up through stellar collisions in dense star clusters. ApJ, 979(2), 237. (www)

  @article{ , abstract = {Dynamical interactions in dense star clusters could significantly influence the properties of black holes, leaving imprints on their gravitational-wave signatures. While previous studies have mostly focused on repeated black hole mergers for spin and mass growth, this work examines the impact of physical collisions and close encounters between black holes and (noncompact) stars. Using Monte Carlo N -body models of dense star clusters, we find that a large fraction of black holes retained upon formation undergo collisions with stars. Within our explored cluster models, the proportion of binary black hole mergers affected by stellar collisions ranges from 10%–60%. If all stellar-mass black holes are initially nonspinning, we find that up to 40% of merging binary black holes may have components with dimensionless spin parameter χ ≳ 0.2 because of prior stellar collisions, while typically about 10% have spins near χ = 0.7 from prior black hole mergers. We demonstrate that young star clusters are especially important environments, as they can produce collisions of black holes with very massive stars, allowing for significant spin-up of the black holes through accretion. Our predictions for black hole spin distributions from these stellar collisions highlight their sensitivity to accretion efficiency, underscoring the need for detailed hydrodynamic calculations to better understand the accretion physics following these interactions.}, archive = {J_ApJ}, author = {Fulya Kıroğlu and Kyle Kremer and Sylvia Biscoveanu and Elena González Prieto and Frederic A. Rasio}, doi = {10.3847/1538-4357/ada26b}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {237}, shortjournal = {The Astrophys. J.}, title = {Black hole accretion and spin-up through stellar collisions in dense star clusters}, volume = {979}, year = {2025}, }
• (2025). The coronal power spectrum from MHD mode conversion above sunspots. ApJ, 979(2), 236. (www)

  @article{ , abstract = {Sunspots are intense regions of magnetic flux that are rooted deep below the photosphere. It is well established that sunspots host magnetohydrodynamic waves, with numerous observations showing a connection to the internal acoustic (or p- )modes of the Sun. The p- modes are fast waves below the equipartition layer and are thought to undergo a double mode conversion as they propagate upward into the atmosphere of sunspots, which can generate Alfvénic modes in the upper atmosphere. We employ 2.5D magnetohydrodynamic numerical simulations to investigate the adiabatic wave propagation and examine the resulting power spectra of coronal Alfvénic waves. A broadband wave source is used, which has a 1D power spectrum mimicking aspects of the observed p- mode power spectrum. We examine magnetoacoustic wave propagation and mode conversion from the photosphere to the corona. Frequency filtering of the upwardly propagating acoustic waves is a natural consequence of a gravitationally stratified atmosphere and plays a key role in shaping the power spectra of mode-converted waves. We demonstrate that the slow and fast magnetoacoustic waves and Alfvén waves above the equipartition layer have similarly shaped power spectra, which are modified versions of the driver spectrum. Notably, the results reveal that the coronal wave power spectra have a peak at a higher frequency than that of the underlying p -mode driver. This matches observations of coronal Alfvénic waves and further supports the role of the mode conversion process as a mechanism for Alfvénic wave generation in the Sun's atmosphere.}, archive = {J_ApJ}, author = {Hemanthi Miriyala and Richard J. Morton and Elena Khomenko and Patrick Antolin and Gert J.J. Botha}, doi = {10.3847/1538-4357/ada26f}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {236}, shortjournal = {The Astrophys. J.}, title = {The coronal power spectrum from MHD mode conversion above sunspots}, volume = {979}, year = {2025}, }
• (2025). Reverberation evidence for stream collision and delayed disk formation in tidal disruption events. ApJ, 979(2), 235. (www)

  @article{ , abstract = {When a star passes through the tidal disruption radius of a massive black hole (BH), it can be torn apart by the tidal force of the BH, known as the tidal disruption event (TDE). Since the observed UV/optical luminosity significantly exceeds the predictions of the compact disk model in classical TDE theory, two competing models, stream collision and envelope reprocessing, have been proposed to address this discrepancy. To distinguish between these models, we investigated the continuum reverberation behaviors for ~30 TDEs with high-quality multiband light curves. We found that over half of them exhibit a positive lag by a few days in UV/optical bands, indicating that their inferred sizes are significantly larger than the envelope sizes in reprocessing. Moreover, X-ray emissions are not only significantly delayed relative to the primary UV/optical peak but also lag behind the rebrightening bump by up to several tens of days, completely different from the X-ray illumination reprocessing. Additionally, the anticorrelated UV−optical continuum in ASASSN-15lh further disfavors the reprocessing scenario. In contrast, the model of stream collisions, combined with delayed accretion disk formation, can provide a unified explanation for the diverse TDE observations, e.g., the optical/X-ray population and the frequently observed rebrightening bump. This model describes a unification scheme wherein the UV/optical emission originates from stream collisions during the early stage of TDE evolution and gradually transitions to being dominated by a accretion disk with detectable X-ray emission in the late stage. After transitioning to a quiescent state, recurrent flares may be observed in some cases, possibly related to repeating partial TDEs.}, archive = {J_ApJ}, author = {Hengxiao Guo and Jingbo Sun and Shuangliang Li and Yan-Fei Jiang and Tinggui Wang and Defu Bu and Ning Jiang and Yanan Wang and Yuhan Yao and Rongfeng Shen and Minfeng Gu and Mouyuan Sun}, doi = {10.3847/1538-4357/ada274}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {235}, shortjournal = {The Astrophys. J.}, title = {Reverberation evidence for stream collision and delayed disk formation in tidal disruption events}, volume = {979}, year = {2025}, }
• (2025). Obliquity dependence of ocean productivity and atmospheric CO2 on earth-like worlds. ApJ, 979(2), 234. (www)

  @article{ , abstract = {Obliquity can shape the habitability of a planet by changing the seasonal availability of incident solar radiation. Changes in incident radiation can lead to changes in the availability of light, temperature, ocean circulation, stratification, and corresponding nutrient availability, all of which are important in determining ocean net primary productivity (NPP). Moreover, a fraction of the carbon assimilated by phytoplankton is sequestered in the deep ocean. Therefore, changes in productivity can alter the distribution of CO 2 between the ocean and atmosphere. In this study, we investigate the effects of obliquity on ocean NPP and the atmospheric CO 2 concentration using ROCKE-3D fully coupled to the NASA GISS Ocean Biogeochemistry Model. We find sea surface temperature primarily controls the NPP response, with both properties reaching a maximum at an obliquity of 45°. We find that the response of the seasonal amplitude of NPP to obliquity is controlled primarily by photosynthetically available radiation and secondarily by changes in nutrient availability. We also find that atmospheric CO 2 increases in response to obliquity, with a minimum at 15° and a maximum at 60°. The obliquity-driven CO 2 changes are controlled primarily by temperature-driven solubility changes, with circulation and biology either enhancing solubility-driven changes at low obliquities or acting against and partially offsetting solubility-driven changes at higher obliquities. The magnitude of obliquity-driven changes is likely too small to be detectable, though future studies are needed to determine whether changing obliquity simultaneously with other orbital parameters can lead to larger, potentially detectable changes in NPP and CO 2 .}, archive = {J_ApJ}, author = {Paul Lerner and Anastasia Romanou and Michael Way and Christopher Colose}, doi = {10.3847/1538-4357/ada277}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {234}, shortjournal = {The Astrophys. J.}, title = {Obliquity dependence of ocean productivity and atmospheric CO2 on earth-like worlds}, volume = {979}, year = {2025}, }
• (2025). Global and local infall in the ASHES sample (GLASHES). i. pilot study in g337.541. ApJ, 979(2), 233. (www)

  @article{ , abstract = {Recent high-angular-resolution observations indicate the need for core growth to form high-mass stars. To understand the gas dynamics at the core scale in the very early evolutionary stages before being severely affected by feedback, we have conducted Atacama Large Millimeter/submillimeter Array (ALMA) observations toward a 70 μ m dark massive clump, G337.541-00.082 as part of the Global and Local infall in the ASHES sample (GLASHES) program. Using dense gas tracers such as N 2 H + ( J = 1–0) and HNC ( J = 3–2), we find signs of infall from the position–velocity diagram and more directly from the blue asymmetry profile in addition to the clump-scale velocity gradient. We estimate infall velocities from intermediate and low-mass cores to be 0.28–1.45 km s −1 , and infall rates to be on the order of 10 −4 –10 −3 M ⊙ yr −1 , both are higher than those measured in low-mass star-forming regions by more than a factor of 5 and an order of magnitude, respectively. We find a strong correlation between the infall velocity with the nonthermal velocity dispersion, suggesting that infall may contribute significantly to the observed line width. Consistent with clump-fed scenarios, we show that the mass infall rate is larger for larger core masses and shorter distances to the clump center. Such high infall rates in cores embedded in IRDCs can be considered as strong signs of core growth, allowing high-mass star formation from intermediate-mass cores that would not initially form high-mass stars at their current mass.}, archive = {J_ApJ}, author = {Kaho Morii and Patricio Sanhueza and Timea Csengeri and Fumitaka Nakamura and Sylvain Bontemps and Guido Garay and Qizhou Zhang}, doi = {10.3847/1538-4357/ada27f}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {233}, shortjournal = {The Astrophys. J.}, title = {Global and local infall in the ASHES sample (GLASHES). i. pilot study in g337.541}, volume = {979}, year = {2025}, }
• (2025). Tearing-mediated alfvénic turbulence in a relativistic plasma. ApJ, 979(2), 232. (www)

  @article{ , abstract = {In astrophysical relativistic plasmas, Alfvénic turbulence exists across a wide range of scales. Similar to a nonrelativistic case, this turbulence can be influenced by the tearing instability. We argue that in an ultrarelativistic pair plasma the tearing effects become significant at the critical scale given by {a}_{t}\sim {d}_{\mathrm{rel}}{\left({L}_{\perp }/{d}_{\mathrm{rel}}\right)}^{n/(4+5n)} , where L ⊥ represents the outer scale of the turbulence and d rel the relativistic electron inertial scale. Here n = 1 corresponds to the Harris magnetic configurations, while n = 2 applies to localized (non-Harris) magnetic profiles of turbulence-generated current sheets. Below the critical scale, the energy spectrum of magnetic fluctuations steepens to W ( k ) dk ∝ k −(7 n +2)/3 n dk . However, this happens only when \tilde{\sigma }\ll {\left({L}_{\perp }/{d}_{\mathrm{rel}}\right)}^{(2+4n)/(4+5n)} , where \tilde{\sigma } is the magnetization parameter based on the magnetic fluctuations. If the opposite inequality holds, the Alfvénic cascade is instead affected by charge starvation at scales below {a}_{\mathrm{ch}}\sim {d}_{\mathrm{rel}}{\left({d}_{\mathrm{rel}}/{L}_{\perp }\right)}^{1/3}{\tilde{\sigma }}^{2/3} , and the energy spectrum becomes steeper than W ( k ) dk ∝ k −3 dk . When d rel is replaced by its nonrelativistic equivalent, our results agree with the nonrelativistic analysis of N. F. Loureiro & S. Boldyrev (2018). In the Harris case n = 1, they agree with the recent relativistic studies by I. Demidov & Y. Lyubarsky.}, archive = {J_ApJ}, author = {Stanislav Boldyrev and Nuno F. Loureiro}, doi = {10.3847/1538-4357/ada28a}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {232}, shortjournal = {The Astrophys. J.}, title = {Tearing-mediated alfvénic turbulence in a relativistic plasma}, volume = {979}, year = {2025}, }
• (2025). Phase-resolved hubble space telescope WFC3 spectroscopy of the weakly irradiated brown dwarf GD 1400 and energy Redistribution–Irradiation trends in six white Dwarf–Brown dwarf binaries. ApJ, 979(2), 231. (www)

  @article{ , abstract = {Irradiated brown dwarfs offer a unique opportunity to bridge the gap between stellar and planetary atmospheres. We present high-quality Hubble Space Telescope/Wide Field Camera 3/G141 phase-resolved spectra of the white dwarf–brown dwarf binary GD 1400, covering more than one full rotation of the brown dwarf. Accounting for brightness variations caused by ZZ Ceti pulsations, we revealed weak (∼1%) phase-curve amplitude modulations originating from the brown dwarf. Subband light-curve exploration in various bands showed no significant wavelength dependence on amplitude or phase shift. Extracted day- and nightside spectra indicated chemically similar hemispheres, with slightly higher dayside temperatures, suggesting efficient heat redistribution or the dominance of radiative escape over atmospheric circulation. A simple radiative and energy redistribution model reproduced the observed temperatures well. Cloud-inclusive models fit the day and night spectra better than cloudless models, indicating global cloud coverage. We also begin qualitatively exploring atmospheric trends across six irradiated brown dwarfs, from the now complete "Dancing with the Dwarfs" white dwarf–brown dwarf sample. The trend we find in the dayside/nightside temperature and irradiation levels is consistent with efficient heat redistribution for irradiation levels less than ∼10 9 erg s −1 cm −2 and decreasing efficiency above that level.}, archive = {J_ApJ}, author = {Rachael C. Amaro and Dániel Apai and Yifan Zhou and Joshua D. Lothringer and Sarah L. Casewell and Xianyu Tan and Ben W. P. Lew and Travis Barman and Mark S. Marley and L. C. Mayorga and Vivien Parmentier}, doi = {10.3847/1538-4357/ada295}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {231}, shortjournal = {The Astrophys. J.}, title = {Phase-resolved hubble space telescope WFC3 spectroscopy of the weakly irradiated brown dwarf GD 1400 and energy Redistribution–Irradiation trends in six white Dwarf–Brown dwarf binaries}, volume = {979}, year = {2025}, }
• (2025). Force analysis of venus’s induced magnetosphere: A multifluid Hall–Magnetohydrodynamics study. ApJ, 979(2), 230. (www)

  @article{ , abstract = {Understanding which processes control atmospheric escape and the loss of water from planetary environments is crucial. The ESA's Venus Express spacecraft has observed a significant depletion in Venus's upper atmosphere, driven by the solar wind. In such scenarios, the electromagnetic force can accelerate planetary ions to energies that allow them to escape from the planet. However, it is extremely challenging to directly measure electromagnetic forces on planetary ions. Here we present a 3D multifluid Hall–magnetohydrodynamics simulation model to investigate electromagnetic force terms and the effects of each term on solar wind plasma and planetary ions. We find that the total electromagnetic force reaches its peak near the bow shock and the magnetic pileup boundary, with obvious asymmetric characteristics, which slows down the solar wind plasma and compresses the heavy ions toward Venus. In addition, the morphology of the convection electric field force shows obvious north–south asymmetry, which leads to the formation of asymmetric structures and plasma flows in the Venusian magnetotail. The electromagnetic force patterns obtained by simulation are consistent with the results and speculation from observations, suggesting that the multifluid model developed here has substantial capacity in further analysis regarding planetary ion escape.}, archive = {J_ApJ}, author = {Nihan Chen and Haoyu Lu and Jinbin Cao and Shibang Li and Xiaoxin Zhang and Yasong Ge and James A. Wild and Yihui Song and Jianxuan Wang and Jianing Zhao and Yuchen Cao}, doi = {10.3847/1538-4357/ada356}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {230}, shortjournal = {The Astrophys. J.}, title = {Force analysis of venus’s induced magnetosphere: A multifluid Hall–Magnetohydrodynamics study}, volume = {979}, year = {2025}, }
• (2025). SCUBADive. i. JWST+ALMA analysis of 289 submillimeter galaxies in COSMOS-web. ApJ, 979(2), 229. (www)

  @article{ , abstract = {JWST has enabled detecting and spatially resolving the heavily dust-attenuated stellar populations of submillimeter galaxies, revealing detail that was previously inaccessible. In this work, we construct a sample of 289 submillimeter galaxies with joint Atacama Large Millimeter/submillimeter Array (ALMA) and JWST constraints in the COSMOS field. Sources are originally selected using the SCUBA-2 instrument and have archival ALMA observations from various programs. Their JWST NIRCam imaging is from COSMOS-Web and PRIMER. We extract multiwavelength photometry in a manner that leverages the unprecedented near-infrared (NIR) spatial resolution of JWST, and we fit the data with spectral energy distribution models to derive photometric redshifts, stellar masses, star formation rates, and optical attenuation. The sample has an average \langle z\rangle =2.{6}_{-0.8}^{+1.0} , \langle {A}_{V}\rangle =2.{5}_{-1.0}^{+1.5} , \langle {\rm{SFR}}\rangle =30{0}_{-200}^{+400}\,{M}_{\odot }\,{{\rm{yr}}}^{-1} , and \langle \mathrm{log}({M}_{* }/{M}_{\odot })\rangle =11.{1}_{-0.5}^{+0.3} . There are 81 (30%) galaxies that have no previous optical/NIR detections, including 75% of the z > 4 subsample ( n = 28). The faintest observed NIR sources have the highest redshifts and largest A V = 4 ± 1. In a preliminary morphology analysis we find that  ∼10% of the members of our sample exhibit spiral arms and 5% host stellar bars, with one candidate bar found at z > 3. Finally, we find that the clustering of JWST sources within 10'' of a submillimeter galaxy is a factor of 2 greater than what is expected based on either random clustering or the distribution of sources around any red galaxy irrespective of a submillimeter detection.}, archive = {J_ApJ}, author = {Jed McKinney and Caitlin M. Casey and Arianna S. Long and Olivia R. Cooper and Sinclaire M. Manning and Maximilien Franco and Hollis Akins and Erini Lambrides and Elaine Gammon and Camila Silva and Fabrizio Gentile and Jorge A. Zavala and Aristeidis Amvrosiadis and Irham Andika and Malte Brinch and Jaclyn B. Champagne and Nima Chartab and Nicole E. Drakos and Andreas L. Faisst and Seiji Fujimoto and Steven Gillman and Ghassem Gozaliasl and Thomas R. Greve and Santosh Harish and Christopher C. Hayward and Michaela Hirschmann and Olivier Ilbert and Boris S. Kalita and Jeyhan S. Kartaltepe and Anton M. Koekemoer and Vasily Kokorev and Daizhong Liu and Georgios Magdis and Henry Joy McCracken and Jason Rhodes and Brant E. Robertson and Margherita Talia and Francesco Valentino and Aswin P. Vijayan}, doi = {10.3847/1538-4357/ada357}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {229}, shortjournal = {The Astrophys. J.}, title = {SCUBADive. i. JWST+ALMA analysis of 289 submillimeter galaxies in COSMOS-web}, volume = {979}, year = {2025}, }
• (2025). The arizona molecular ISM survey with the SMT: Variations in the CO(2–1)/CO(1–0) line ratio across the galaxy population. ApJ, 979(2), 228. (www)

  @article{ , abstract = {The J = 1 → 0 spectral line of carbon monoxide (CO(1–0)) is the canonical tracer of molecular gas. However, CO(2–1) is frequently used in its place, following the assumption that the higher-energy line can be used to infer the CO(1–0) luminosity and molecular gas mass. The use of CO(2–1) depends on a knowledge of the ratio between CO(2–1) and CO(1–0) luminosities, r 21 . Here, we present galaxy-integrated r 21 measurements for 122 galaxies spanning stellar masses from 10 9 to 10 11.5 M ⊙ and star formation rates (SFRs) from 0.08 to 35 M ⊙ yr −1 . We find strong trends between r 21 and SFR, SFR surface density, star formation efficiency, and distance from the star formation main sequence (SFMS). We show that the assumption of a constant r 21 can introduce biases into the molecular gas trends in galaxy population studies and demonstrate how this affects the recovery of important galaxy scaling relations, including the Kennicutt–Schmidt law and the relation between SFMS offset and star formation efficiency. We provide a prescription that accounts for variations in r 21 as a function of SFR and can be used to convert between CO(2–1) and CO(1–0) when only one line is available. Our prescription matches variations in r 21 for both AMISS and literature samples and can be used to derive more accurate gas masses from CO(2–1) observations.}, archive = {J_ApJ}, author = {Ryan P. Keenan and Daniel P. Marrone and Garrett K. Keating}, doi = {10.3847/1538-4357/ada361}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {228}, shortjournal = {The Astrophys. J.}, title = {The arizona molecular ISM survey with the SMT: Variations in the CO(2–1)/CO(1–0) line ratio across the galaxy population}, volume = {979}, year = {2025}, }
• (2025). Unveiling the emission mechanisms of blazar PKS 1510−089. II. Jet−BLR connection and black hole mass estimation. ApJ, 979(2), 227. (www)

  @article{ , abstract = {The flat spectrum radio quasar PKS 1510−089 is one of the most active blazars across the entire electromagnetic spectrum, displaying periods of flaring activity. This study explores its spectral variability over a decade. By employing the nonthermal dominance parameter, we analyze the H β and λ 5100 continuum light curves, as well as the FWHM of the H β emission line, to identify whether the primary source of the continuum emission is the accretion disk or the jet during activity periods. Our results show an anticorrelation between the FWHM and the luminosity of the H β emission line across all data sets. This indicates that variations in H β luminosity consistently reflect the canonical broad-line region (BLR), irrespective of whether the primary ionizing source is the accretion disk or the jet. The anticorrelation persisted when comparing the FWHM of H β against the luminosity at λ 5100 in the disk dominance regime. These findings, along with the observation that flaring events in the λ 5100 continuum, attributed to the jet, coincide with flares in the H β emission line, suggest that the base of the jet is located within the BLR. Based on the 219 spectra within the disk dominance regime, we estimated a mean black hole mass of M BH = 2.85 ± 0.37 × 10 8 M ⊙ .}, archive = {J_ApJ}, author = {Alfredo Amador-Portes and Vahram Chavushyan and Víctor M. Patiño-Álvarez and José Ramón-Valdés}, doi = {10.3847/1538-4357/ada38b}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {227}, shortjournal = {The Astrophys. J.}, title = {Unveiling the emission mechanisms of blazar PKS 1510−089. II. Jet−BLR connection and black hole mass estimation}, volume = {979}, year = {2025}, }
• (2025). Quasi-parallel antisunward-propagating whistler waves associated with the electron deficit in the near-sun solar wind: Particle-in-cell simulation. ApJ, 979(2), 226. (www)

  @article{ , abstract = {In situ observations of the solar wind have shown that the electron velocity distribution function (VDF) consists of a quasi-Maxwellian core, comprising most of the electron population, and two sparser components: the halo, which are suprathermal and quasi-isotropic electrons, and an escaping beam population, the strahl. Recent Parker Solar Probe (PSP) and Solar Orbiter (SO) observations have added one more ingredient to the known nonthermal features, the deficit—a depletion in the sunward region of the VDF, already predicted by exospheric models but never so extensively observed. By employing particle-in-cell simulations, we study electron VDFs that reproduce those typically observed in the inner heliosphere and investigate whether the electron deficit may contribute to the onset of kinetic instabilities. Previous studies and in situ observations show that strahl electrons drive oblique whistler waves unstable, which in turn scatters them. As a result, suprathermal electrons can occupy regions of phase space where they fulfill resonance conditions with the parallel-propagating whistler wave. The suprathermal electrons lose kinetic energy, resulting in the generation of unstable waves. The sunward side of the VDF, initially depleted of electrons, is gradually filled, as this wave−particle interaction process, triggered by the depletion itself, takes place. Our findings are compared and validated against current PSP and SO observations: among others, our study provides a mechanism explaining the presence in the heliosphere of regularly observed parallel antisunward whistler waves, suggests why these waves are frequently observed concomitant with distributions presenting an electron deficit, and describes a noncollisional heat flux regulating process.}, archive = {J_ApJ}, author = {Alfredo Micera and Daniel Verscharen and Jesse T. Coburn and Maria Elena Innocenti}, doi = {10.3847/1538-4357/ada3d7}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {226}, shortjournal = {The Astrophys. J.}, title = {Quasi-parallel antisunward-propagating whistler waves associated with the electron deficit in the near-sun solar wind: Particle-in-cell simulation}, volume = {979}, year = {2025}, }
• (2025). Precise measurement of the cosmic-ray spectrum and 〈ln a〉 by LHAASO: Connecting the galactic to the extragalactic components. ApJ, 979(2), 225. (www)

  @article{ , abstract = {Recently, the LHAASO Collaboration has provided precise measurements of the cosmic rays (CRs) all-particle energy spectrum and mean logarithmic mass \left\langle \mathrm{ln}A\right\rangle from 0.3 to 30 PeV. Combining the CR measurements by AMS-02 and DAMPE in space and those by LHAASO and Auger on the ground, we construct a model to recover all these measurements from tens of GeV to tens of EeV. We find that the LHAASO measurement is crucial in the model construction by connecting the Galactic component to the extragalactic component. The precise measurements of CR spectra for individual species by AMS-02 and DAMPE together with the newest LHAASO results clearly indicate three Galactic CR components, that is, a soft low-energy background, a hard high-energy component, and a local source contribution. However, the LHAASO data show that above ∼10 16 eV, a nonnegligible extra component, possibly of extragalactic origin, must be included. Combining the Auger results and the LHAASO results, we figure out the extragalactic CRs that need at least two components at lower and higher energies. Thanks to the measurements by LHAASO, the constraints on the model parameters are quite stringent. The spectrum features and mass measurements in all energy ranges are all well reproduced in the model.}, archive = {J_ApJ}, author = {Xing-Jian Lv and Xiao-Jun Bi and Kun Fang and Yi-Qing Guo and Hui-Hai He and Ling-Ling Ma and Peng-Fei Yin and Qiang Yuan and Meng-Jie Zhao}, doi = {10.3847/1538-4357/ada426}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {225}, shortjournal = {The Astrophys. J.}, title = {Precise measurement of the cosmic-ray spectrum and 〈ln a〉 by LHAASO: Connecting the galactic to the extragalactic components}, volume = {979}, year = {2025}, }
• (2025). Analytical verification of the normal vector determination methods for planar magnetic structures. ApJ, 979(2), 224. (www)

  @article{ , abstract = {Minimum variance analysis of magnetic fields (MVAB) is conventionally implemented to determine the normal vector of a planar magnetic structure (PMS) for which the average of the normal magnetic field component vanishes (i.e., \left\langle {B}_{n}\right\rangle = 0). A more suitable normal vector determination method for single-spacecraft measurements, based on the minimum variance concept, is recommended for PMS studies, namely the MVAB method associated with the constraint \left\langle {B}_{n}\right\rangle = 0 (MVABC). An analytical PMS model is employed to verify the performance of the MVAB and MVABC methods for three different types of PMSs, under the circumstances that the {B}_{n} values are highly fluctuated but the \left\langle {B}_{n}\right\rangle remains zero. The results show that MVABC outperforms MVAB in estimating the PMS normal vector. By analyzing a large number of test data sets randomly selected from the original data set, the conclusion remains unchanged. The normal of a PMS discontinuity, which is associated with significant {B}_{n} fluctuations, is accurately predicted by MVABC and the cross-product method, as compared to MVAB. Moreover, the normal of the discontinuity aligns with the PMS normal, as expected. Two PMS events observed by the Advanced Composition Explorer spacecraft in the sheath of an interplanetary coronal mass ejection are presented. From the MVAB perspective, these two events are not classified as PMSs. The estimated normals of the in situ PMS discontinuities from the cross-product method form angles between 10° and 20° with the predicted PMS normals from MVABC. Discussions are given regarding the failure of the MVAB method in PMS identification.}, archive = {J_ApJ}, author = {Wai-Leong Teh}, doi = {10.3847/1538-4357/ada446}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {224}, shortjournal = {The Astrophys. J.}, title = {Analytical verification of the normal vector determination methods for planar magnetic structures}, volume = {979}, year = {2025}, }
• (2025). Merger response of halo anisotropy properties. ApJ, 979(2), 223. (www)

  @article{ , abstract = {Anisotropy properties—halo spin, shape, position offset, velocity offset, and orientation—are an important family of dark matter halo properties that indicate the level of directional variation of the internal structures of halos. These properties reflect the dynamical state of halos, which in turn depends on the mass assembly history. In this work, we study the evolution of anisotropy properties in response to merger activity using the IllustrisTNG simulations. We find that the response trajectories of the anisotropy properties significantly deviate from secular evolution. These trajectories have the same qualitative features and timescales across a wide range of merger and host properties. We propose explanations for the behavior of these properties and connect their evolution to the relevant stages of merger dynamics. We measure the relevant dynamical timescales. We also explore the dependence of the strength of the response on time of merger, merger ratio, and mass of the main halo. These results provide insight into the physics of halo mergers and their effects on the statistical behavior of halo properties. This study paves the way toward a physical understanding of scaling relations, particularly to how systematics in their scatter are connected to the mass assembly histories of halos.}, archive = {J_ApJ}, author = {Kuan Wang and Philip Mansfield and Dhayaa Anbajagane and Camille Avestruz}, doi = {10.3847/1538-4357/ada4aa}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {223}, shortjournal = {The Astrophys. J.}, title = {Merger response of halo anisotropy properties}, volume = {979}, year = {2025}, }
• (2025). PUI heating in the supersonic solar wind. ApJ, 979(2), 222. (www)

  @article{ , abstract = {The outer heliosphere is profoundly influenced by nonthermal energetic pickup ions (PUIs), which dominate the internal pressure of the solar wind beyond ~10 au, surpassing both solar wind and magnetic pressures. PUIs are formed mostly through charge exchange between interstellar neutral atoms and solar wind ions. This study examines the apparent heating of PUIs in the distant supersonic solar wind before reaching the heliospheric termination shock. New Horizons' SWAP observations reveal an unexpected PUI temperature change between 2015 and 2020, with a notable bump in PUI temperature. Concurrent observations from the ACE and Wind spacecraft at 1 au indicate a ~50% increase in solar wind dynamic pressure at the end of 2014. Our simulation suggests that the bump observed in the PUI temperature by New Horizons is largely associated with the enhanced solar wind dynamic pressure observed at 1 au. Additional PUI temperature enhancements imply the involvement of other heating mechanisms. Analysis of New Horizons data reveals a correlation between shocks and PUI heating during the declining phase of the solar cycle. Using a PUI-mediated plasma model, we explore shock structures and PUI heating, finding that shocks preferentially heat PUIs over the thermal solar wind in the outer heliosphere. We also show that the broad shock thickness observed by New Horizons is due to the large diffusion coefficient associated with PUIs. Shocks and compression regions in the distant supersonic solar wind lead to elevated PUI temperatures and thus they can increase the production of energetic neutral atoms with large energy.}, archive = {J_ApJ}, author = {Parisa Mostafavi and Laxman Adhikari and Bishwas L. Shrestha and Gary P. Zank and Merav Opher and Matthew E. Hill and Heather A. Elliott and Pontus C. Brandt and Ralph L. McNutt and David J. McComas and Andrew R. Poppe and Elena Provornikova and Romina Nikoukar and Peter Kollmann and S. Alan Stern and Kelsi N. Singer and Anne Verbiscer and Joel Parker}, doi = {10.3847/1538-4357/ada891}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {222}, shortjournal = {The Astrophys. J.}, title = {PUI heating in the supersonic solar wind}, volume = {979}, year = {2025}, }
• (2025). Enhancing mars gravity field solutions with china’s tianwen-1 tracking data. ApJ, 979(2), 221. (www)

  @article{ , abstract = {The Tianwen-1 (TW1) mission, which successfully entered Mars's orbit in 2021, provides a valuable data set for enhancing the understanding of Mars's gravity field. The highly elliptical near-polar orbit of the TW1 orbiter offers unique sensitivity to long-wavelength gravity signals, complementing the contributions of low-altitude missions like the Mars Reconnaissance Orbiter (MRO). In this study, we used 4 months of TW1 radio tracking data in combination with MRO data to develop a new Mars gravity field model up to degree and order 50. We evaluated the improvement of gravity field determination through power spectrum analysis, gravity anomaly maps, and trajectory precision assessment. The result shows significant improvements in accuracy up to degree and order 30, with an average enhancement of 38% in the zonal harmonic coefficients. There are obvious differences between the two gravity field models in gravity anomaly maps. The range of gravity anomaly errors improves after incorporating TW1 data, with the maximum error decreasing from 53.4 to 46.4 mGal and the average error improving from 8.4 to 7.3 mGal. Additionally, orbit determination experiments confirm that the fused gravity field model enhances trajectory modeling for both MRO and TW1. These findings highlight the scientific value of TW1 tracking data in advancing Mars's gravity field modeling and provide critical insights for future deep-space missions.}, archive = {J_ApJ}, author = {Shangbiao Sun and Jianguo Yan and Shanhong Liu and Chongyang Wang and Denggao Qiu and Jean-Pierre Barriot}, doi = {10.3847/1538-4357/ada938}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {221}, shortjournal = {The Astrophys. J.}, title = {Enhancing mars gravity field solutions with china’s tianwen-1 tracking data}, volume = {979}, year = {2025}, }
• (2025). Sledgehamr: Simulating scalar fields with adaptive mesh refinement. ApJ, 979(2), 220. (www)

  @article{ , abstract = {Understanding the nonlinear dynamics of coupled scalar fields often necessitates simulations on a 3D mesh. These simulations can be computationally expensive if a large scale separation is involved. A common solution is adaptive mesh refinement, which, however, greatly increases a simulation's complexity. In this work, we present sledgehamr , an AMReX -based code package to make the simulation of coupled scalar fields on an adaptive mesh more accessible. Compatible with both GPU and CPU clusters, sledgehamr offers a flexible and customizable framework. While the code had been primarily developed to evolve axion string networks, this framework enables various other applications, such as the study of gravitational waves sourced by the dynamics of scalar fields.}, archive = {J_ApJ}, author = {Malte Buschmann}, doi = {10.3847/1538-4357/ad9ea2}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {220}, shortjournal = {The Astrophys. J.}, title = {Sledgehamr: Simulating scalar fields with adaptive mesh refinement}, volume = {979}, year = {2025}, }
• (2025). Multiwavelength emission of gamma-ray burst prompt phase. II. spectral polarimetry. ApJ, 979(2), 219. (www)

  @article{ , abstract = {Polarization spectra were predicted within the photosphere model. To seek more clues to distinguish between the models, both the time-resolved and time-integrated polarization spectra from optical band to MeV gamma-rays of the magnetic reconnection model are studied here. There are two newly found differences between the two models. First, the time-integrated polarization degree of the magnetic reconnection model would in general increase with frequency for on-axis observations, while it is not monotonous for the photosphere model. Second, the variations of both the time-integrated and the time-resolved polarization angles (PAs) with frequency of the magnetic reconnection model are not random, while the time-integrated PA varies randomly with frequency for the photosphere model. Therefore, future energy-resolved polarization analysis could distinguish between the two models. In addition, the PA rotation spectra are studied for the first time. The rotation value of PA within the burst duration will decrease with the increase of the observational energy band. Most significant PA rotation would happen for slightly off-axis observations in each energy band. The PA would rotate even for on-axis observations in the optical band. Compared with the aligned magnetic field case, the PA rotation is quite rare in the gamma-ray band for the case with a toroidal field in the radiation region.}, archive = {J_ApJ}, author = {Jia-Sheng Li and Mi-Xiang Lan}, doi = {10.3847/1538-4357/ada5f1}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {219}, shortjournal = {The Astrophys. J.}, title = {Multiwavelength emission of gamma-ray burst prompt phase. II. spectral polarimetry}, volume = {979}, year = {2025}, }
• (2025). Planet–Planet scattering and von Zeipel–Lidov–Kozai Migration—The dynamical history of HAT-P-11. ApJ, 979(2), 218. (www)

  @article{ , abstract = {The two planets of the HAT-P-11 system represent fascinating dynamical puzzles due to their significant eccentricities and orbital misalignments. In particular, HAT-P-11 b is in a close-in orbit in which tides should have circularized well within the age of the system. Here we propose a two-step dynamical process that can reproduce all intriguing aspects of the system. We first invoke planet–planet scattering to generate significant eccentricities and mutual inclinations between the planets. We then propose that this misalignment initiated von-Zeipel-Lidov-Kozai cycles and high-eccentricity migration that ultimately brought HAT-P-11 b to its present-day orbit. We find that this scenario is fully consistent only when significant tidally driven radius inflation is accounted for during the tidal migration. We present a suite of N -body simulations exploring each phase of evolution and show that this scenario is consistent with all observational posteriors and the reported age of the system.}, archive = {J_ApJ}, author = {Tiger Lu and Qier An and Gongjie Li and Sarah C. Millholland and Malena Rice and G. Mirek Brandt and Timothy D. Brandt}, doi = {10.3847/1538-4357/ad9b79}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {218}, shortjournal = {The Astrophys. J.}, title = {Planet–Planet scattering and von Zeipel–Lidov–Kozai Migration—The dynamical history of HAT-P-11}, volume = {979}, year = {2025}, }
• (2025). The arp 240 galaxy merger: A detailed look at the molecular Kennicutt–Schmidt star formation law on subkiloparsec scales. ApJ, 979(2), 217. (www)

  @article{ , abstract = {The molecular Kennicutt–Schmidt Law has been key for understanding star formation (SF) in galaxies across all redshifts. However, recent subkiloparsec observations of nearby galaxies reveal deviations from the nearly unity slope ( N ) obtained with disk-averaged measurements. We study SF and molecular gas (MG) distribution in the early-stage luminous infrared galaxy merger Arp 240 (NGC 5257-8). Using Very Large Array radio continuum (RC) and Atacama Large Millimeter/submillimeter Array CO(2–1) observations at 500 pc scale, with a uniform grid analysis, we estimate SF rates and MG surface densities (Σ SFR and {{\rm{\Sigma }}}_{{{\rm{H}}}_{2}} , respectively). In Arp 240, N is sublinear at 0.52 ± 0.17. For NGC 5257 and NGC 5258, N is 0.52 ± 0.16 and 0.75 ± 0.15, respectively. We identify two SF regimes: high surface brightness (HSB) regions in RC with N ~ 1, and low surface brightness (LSB) regions with shallow N (ranging 0.15 ± 0.09–0.48 ± 0.04). Median CO(2–1) linewidth and MG turbulent pressure ( P turb ) are 25 km s −1 and 9 × 10 5 K cm −3 . No significant correlation was found between Σ SFR and CO(2–1) linewidth. However, Σ SFR correlates with P turb , particularly in HSB regions ( ρ > 0.60). In contrast, SF efficiency moderately anticorrelates with P turb in LSB regions but shows no correlation in HSB regions. Additionally, we identify regions where peaks in SF and MG are decoupled, yielding a shallow N (≤0.28 ± 0.18). Overall, the range of N reflects distinct physical properties and distribution of both the SF and MG, which can be masked by disk-averaged measurements.}, archive = {J_ApJ}, author = {A. Saravia and E. Rodas-Quito and L. Barcos-Muñoz and A. S. Evans and D. Kunneriath and G. Privon and Y. Song and I. Yoon and K. L. Emig and M. Sánchez-García and S. T. Linden and K. Green and M. Johnstone and J. Nagarajan-Swenson and G. A. Meza and E. Momjian and L. Armus and V. Charmandaris and T. Diaz-Santos and C. Eibensteiner and J. Howell and H. Inami and J. Kader and C. Ricci and E. Treister and V. U and T. Bohn and D. B. Sanders}, doi = {10.3847/1538-4357/ad9bab}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {217}, shortjournal = {The Astrophys. J.}, title = {The arp 240 galaxy merger: A detailed look at the molecular Kennicutt–Schmidt star formation law on subkiloparsec scales}, volume = {979}, year = {2025}, }
• (2025). 3D convective urca process in a simmering white dwarf. ApJ, 979(2), 216. (www)

  @article{ , abstract = {A proposed setting for thermonuclear (Type Ia) supernovae is a white dwarf that has gained mass from a companion to the point of carbon ignition in the core. In the early stages of carbon burning, called the simmering phase, energy released by the reactions in the core drive the formation and growth of a core convection zone. One aspect of this phase is the convective Urca process, a linking of weak nuclear reactions to convection, which may alter the composition and structure of the white dwarf. The convective Urca process is not well understood and requires 3D fluid simulations to properly model the turbulent convection, an inherently 3D process. Because the neutron excess of the fluid both sets and is set by the extent of the convection zone, the realistic steady state can only be determined in simulations with real 3D mixing processes. Additionally, the convection is relatively slow (Mach number less than 0.005) and thus a low Mach number method is needed to model the flow over many convective turnovers. Using the MAESTROeX low Mach number hydrodynamic software, we present the first full-star 3D simulations of the A = 23 convective Urca process, spanning hundreds of convective turnover times. Our findings on the extent of mixing across the Urca shell, the characteristic velocities of the flow, the energy-loss rates due to neutrino emission, and the structure of the convective boundary can be used to inform 1D stellar models that track the longer-timescale evolution.}, archive = {J_ApJ}, author = {Brendan Boyd and Alan Calder and Dean Townsley and Michael Zingale}, doi = {10.3847/1538-4357/ad9bb0}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {216}, shortjournal = {The Astrophys. J.}, title = {3D convective urca process in a simmering white dwarf}, volume = {979}, year = {2025}, }
• (2025). The MBH–M∗ relation up to z ∼ 2 through decomposition of COSMOS-web NIRCam images. ApJ, 979(2), 215. (www)

  @article{ , abstract = {Our knowledge of relations between supermassive black holes and their host galaxies at z ≳ 1 is still limited, even though being actively sought out to z ∼ 6. Here, we use the high resolution and sensitivity of JWST to measure the host galaxy properties for 107 X-ray-selected type-I active galactic nuclei (AGNs) at 0.68 < z < 2.5 with rest-frame optical/near-infrared imaging from COSMOS-Web and PRIMER. Black hole masses ( \mathrm{log}\left({M}_{{\rm{BH}}}/{M}_{\odot }\right)\sim 6.9-9.6 ) are available from previous spectroscopic campaigns. We extract the host galaxy components from four NIRCam broadband images and the Hubble Space Telescope/Advanced Camera for Surveys F814W image by applying a 2D image decomposition technique. We detect the host galaxy for  ∼90% of the sample after subtracting the unresolved AGN emission. With host photometry free of AGN emission, we determine the stellar mass of the host galaxies to be \mathrm{log}\left({M}_{* }/{M}_{\odot }\right)\sim 9.5-11.6 through spectral energy distribution fitting and measure the evolution of the mass relation between SMBHs and their host galaxies. Considering selection biases and measurement uncertainties, we find that the M BH / M * ratio evolves as {\left(1+z\right)}^{0.4{8}_{-0.62}^{+0.31}} thus remains essentially constant or exhibits mild evolution up to z ∼ 2.5. We also see an amount of scatter ( {\sigma }_{\mu }=0.3{0}_{-0.13}^{+0.14} ), similar to the local relation and consistent with low- z studies, and a noncausal cosmic assembly history where mergers contribute to the statistical averaging toward the local relation is still feasible. We highlight improvements to come with larger samples from JWST and, particularly, Euclid, which will exceed the statistical power of current wide and deep surveys.}, archive = {J_ApJ}, author = {Takumi S. Tanaka and John D. Silverman and Xuheng Ding and Knud Jahnke and Benny Trakhtenbrot and Erini Lambrides and Masafusa Onoue and Irham Taufik Andika and Angela Bongiorno and Andreas L. Faisst and Steven Gillman and Christopher C. Hayward and Michaela Hirschmann and Anton Koekemoer and Vasily Kokorev and Zhaoxuan Liu and Georgios E. Magdis and Alvio Renzini and Caitlin Casey and Nicole E. Drakos and Maximilien Franco and Ghassem Gozaliasl and Jeyhan Kartaltepe and Daizhong Liu and Henry Joy McCracken and Jason Rhodes and Brant Robertson and Sune Toft}, doi = {10.3847/1538-4357/ad9d0a}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {215}, shortjournal = {The Astrophys. J.}, title = {The MBH–M∗ relation up to z ∼ 2 through decomposition of COSMOS-web NIRCam images}, volume = {979}, year = {2025}, }
• (2025). The magnetically induced radial velocity variation of gliese 341 and an upper limit to the mass of its transiting earth-sized planet. ApJ, 979(2), 214. (www)

  @article{ , abstract = {The Transiting Exoplanet Survey Satellite (TESS) mission identified a potential 0.88 R ⊕ planet with a period of 7.577 days, orbiting the nearby M1V star GJ 341 (TOI 741.01). This system has already been observed by the James Webb Space Telescope (JWST) to search for presence of an atmosphere on this planet. Here, we present an in-depth analysis of the GJ 341 system using all available public data. We provide improved parameters for the host star, an updated value of the planet radius, and support the planetary nature of the object (now GJ 341 b). We use 57 HARPS radial velocities to model the magnetic cycle and activity of the host star, and constrain the mass of GJ 341 b to upper limits of 4.0 M ⊕ (3 σ ) and 2.9 M ⊕ (1 σ ). We also rule out the presence of additional companions with M sin i > 15.1 M ⊕ , and P < 1750 days, and the presence of contaminating background objects during the TESS and JWST observations. These results provide key information to aid the interpretation of the recent JWST atmospheric observations and other future observations of this planet.}, archive = {J_ApJ}, author = {Victoria DiTomasso and Mercedes López-Morales and Sarah Peacock and Luca Malavolta and James Kirk and Kevin B. Stevenson and Guangwei Fu and Jacob Lustig-Yaeger}, doi = {10.3847/1538-4357/ad9dd3}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {214}, shortjournal = {The Astrophys. J.}, title = {The magnetically induced radial velocity variation of gliese 341 and an upper limit to the mass of its transiting earth-sized planet}, volume = {979}, year = {2025}, }
• (2025). Identifying galactic substructures in 5D space using all-sky RR lyrae stars in gaia DR3. ApJ, 979(2), 213. (www)

  @article{ , abstract = {Motivated by the vast gap between photometric and spectroscopic data volumes, there is great potential in using 5D kinematic information to identify and study substructures of the Milky Way. We identify substructures in the Galactic halo using 46,575 RR Lyrae stars (RRLs) from Gaia Data Release 3, with photometric metallicities and distances newly estimated by X.-Y. Li et al. Assuming a Gaussian prior distribution of radial velocity, we calculate the orbital distribution characterized by the integrals of motion for each RRL, based on its 3D positions, proper motions, and corresponding errors, and then apply the friends-of-friends algorithm to identify groups moving along similar orbits. We have identified several known substructures, including the Sagittarius stream, the Hercules-Aquila Cloud (HAC), the Virgo Overdensity (VOD), Gaia-Enceladus-Sausage (GES), the Orphan-Chenab stream, Cetus-Palca, the Helmi streams, Sequoia, Wukong, and the Large Magellanic Cloud leading arm, as well as 18 unknown groups. Our findings indicate that the HAC and VOD have kinematic and chemical properties remarkably similar to GES, with most HAC and VOD members exhibiting eccentricity as high as GES, suggesting that they may share a common origin with GES. The ability to identify low-mass and spatially dispersed substructures further demonstrates the potential of our method, which breaks the limit of spectroscopic surveys and is competent for probing substructures throughout the whole Galaxy. Finally, we also identify 18 unknown groups with good spatial clustering and proper-motion consistency, suggesting the possibility of further excavation of Milky Way substructures in the future with only 5D data.}, archive = {J_ApJ}, author = {Shenglan Sun and Fei Wang and Huawei Zhang and Xiang-Xiang Xue and Yang Huang and Ruizhi Zhang and Hans-Walter Rix and Xinyi Li and Gaochao Liu and Lan Zhang and Chengqun Yang and Shuo Zhang}, doi = {10.3847/1538-4357/ad9de0}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {213}, shortjournal = {The Astrophys. J.}, title = {Identifying galactic substructures in 5D space using all-sky RR lyrae stars in gaia DR3}, volume = {979}, year = {2025}, }
• (2025). Causal discovery in astrophysics: Unraveling supermassive black hole and galaxy coevolution. ApJ, 979(2), 212. (www)

  @article{ , abstract = {Correlation does not imply causation, but patterns of statistical association between variables can be exploited to infer a causal structure (even with purely observational data) with the burgeoning field of causal discovery. As a purely observational science, astrophysics has much to gain by exploiting these new methods. The supermassive black hole (SMBH)–galaxy interaction has long been constrained by observed scaling relations, which is low-scatter correlations between variables such as SMBH mass and the central velocity dispersion of stars in a host galaxy's bulge. This study, using advanced causal discovery techniques and an up-to-date data set, reveals a causal link between galaxy properties and dynamically measured SMBH masses. We apply a score-based Bayesian framework to compute the exact conditional probabilities of every causal structure that could possibly describe our galaxy sample. With the exact posterior distribution, we determine the most likely causal structures and notice a probable causal reversal when separating galaxies by morphology. In elliptical galaxies, bulge properties (built from major mergers) tend to influence SMBH growth, while, in spiral galaxies, SMBHs are seen to affect host galaxy properties, potentially through feedback in gas-rich environments. For spiral galaxies, SMBHs progressively quench star formation, whereas, in elliptical galaxies, quenching is complete, and the causal connection has reversed. Our findings support theoretical models of hierarchical assembly of galaxies and active galactic nuclei feedback regulating galaxy evolution. Our study suggests the potentiality for further exploration of causal links in astrophysical and cosmological scaling relations, as well as any other observational science.}, archive = {J_ApJ}, author = {Zehao Jin and Mario Pasquato and Benjamin L. Davis and Tristan Deleu and Yu Luo and Changhyun Cho and Pablo Lemos and Laurence Perreault-Levasseur and Yoshua Bengio and Xi Kang and Andrea Valerio Macciò and Yashar Hezaveh}, doi = {10.3847/1538-4357/ad9ded}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {212}, shortjournal = {The Astrophys. J.}, title = {Causal discovery in astrophysics: Unraveling supermassive black hole and galaxy coevolution}, volume = {979}, year = {2025}, }
• (2025). Constraining solar wind transport model parameters using bayesian analysis. ApJ, 979(2), 211. (www)

  @article{ , abstract = {We apply nested-sampling Bayesian analysis to a model for the transport of magnetohydrodynamic-scale solar wind fluctuations. The dual objectives are to obtain improved constraints on parameters present in the turbulence transport model (TTM) and to support quantitative comparisons of the quality of distinct versions of the transport model. The TTMs analyzed are essentially the 1D steady-state ones presented in Breech et al. that describe the radial evolution of the energy, correlation length, and normalized cross helicity of the fluctuations, together with the proton temperature, in prescribed background solar wind fields. Modeled effects present in the TTM include nonlinear turbulence interactions, shear driving, and energy injection associated with pickup-ions. Each of these modeled effects involves adjustable parameters that we seek to constrain using Bayesian analysis. We find that, given the TTMs and observational data sets analyzed, the most appropriate TTM to recommend corresponds to 2D fluctuations and has von Kármán–Howarth parameters of α ≈ 0.16 and β ≈ 0.10, along with reasonably standard values for the other adjustable parameters. The analysis also indicates that it is advantageous to include pickup ion effects in the lengthscale evolution equation by assuming Z 2 β / α λ is locally conserved. Such Bayesian analysis is readily extended to more sophisticated solar wind models, space weather models, and might lead to improved predictions of, for example, solar flare and coronal mass ejection interactions with the Earth.}, archive = {J_ApJ}, author = {Mark A. Bishop and Sean Oughton and Tulasi N. Parashar and Yvette C. Perrott}, doi = {10.3847/1538-4357/ad9f2f}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {211}, shortjournal = {The Astrophys. J.}, title = {Constraining solar wind transport model parameters using bayesian analysis}, volume = {979}, year = {2025}, }
• (2025). Spectral energy distribution variability of the blazar OJ 287 during 2009–2021. ApJ, 979(2), 210. (www)

  @article{ , abstract = {Using nearly simultaneous radio, near-infrared, optical, and ultraviolet (UV) data collected since 2009, we constructed 106 spectral energy distributions (SEDs) of the blazar OJ 287. These SEDs are well fitted by a log-parabolic model. By classifying the data into "flare" and "quiescent" segments, we find that the median flux at the peak frequency of the SEDs during the flare segments is 0.37 ± 0.22 dex higher compared to the quiescent segments, while no significant differences are observed in the median values of the curvature parameter b or the peak frequency \mathrm{log}\nu {\rm{p}} . A significant bluer-when-brighter trend is confirmed through the relation between the V magnitude and B − V color index, with this trend being stronger in the flare segments. Additionally, a significant anticorrelation is detected between \mathrm{log}\nu {\rm{p}} and b , with a slope of 5.79 in the relation between 1/ b and \mathrm{log}\nu {\rm{p}} , closer to the prediction from a statistical acceleration model than a stochastic acceleration interpretation, though a notable discrepancy persists. This discrepancy indicates that additional factors—such as deviations from idealized conditions or radiative contributions, such as the thermal emission from the accretion disk in the optical–UV range during quiescent states—may play a role in producing the observed steeper slope. Within the framework of the statistical acceleration mechanism, the lack of correlation between the change in the peak intensity and the change in the peak frequency suggests that the change in the electron energy distribution is unlikely to be responsible for the time-dependent SED changes. Instead, changes in Doppler boosting or magnetic fields may have a greater influence.}, archive = {J_ApJ}, author = {Wenwen Zuo and Alok C. Gupta and Minfeng Gu and Mauri J. Valtonen and Svetlana G. Jorstad and Margo F. Aller and Anne Lähteenmäki and Sebastian Kiehlmann and Pankaj Kushwaha and Hugh D. Aller and Liang Chen and Anthony C. S. Readhead and Merja Tornikoski and Qi Yuan}, doi = {10.3847/1538-4357/ad9f30}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {210}, shortjournal = {The Astrophys. J.}, title = {Spectral energy distribution variability of the blazar OJ 287 during 2009–2021}, volume = {979}, year = {2025}, }
• (2025). Not just winds: Why models find that binary black hole formation is metallicity-dependent, while binary neutron star formation is not. ApJ, 979(2), 209. (www)

  @article{ , abstract = {Both detailed and rapid population studies alike predict that binary black hole (BHBH) formation is orders of magnitude more efficient at low metallicity than high metallicity, while binary neutron star (NSNS) formation remains mostly flat with metallicity, and black hole–neutron star mergers show intermediate behavior. This finding is a key input to employ double compact objects as tracers of low-metallicity star formation, as spectral sirens, and for merger rate calculations. Yet the literature offers various (sometimes contradicting) explanations for these trends. We investigate the dominant cause for the metallicity dependence of double compact object formation. We find that the BHBH formation efficiency at low metallicity is set by initial condition distributions, and conventional simulations suggest that about one in eight interacting binary systems with sufficient mass to form black holes will lead to a merging BHBH. We further find that the significance of metallicities in double compact object formation is a question of formation channel. The stable mass transfer and chemically homogeneous evolution channels mainly diminish at high metallicities due to changes in stellar radii, while the common envelope channel is primarily impacted by the combined effects of stellar winds and mass-scaled natal kicks. Outdated giant wind prescriptions exacerbate the latter effect, suggesting that BHBH formation may be much less metallicity-dependent than previously assumed. NSNS formation efficiency remains metallicity-independent, as they form exclusively through the common envelope channel, with natal kicks that are assumed to be uncorrelated with mass. Forthcoming gravitational-wave observations will provide valuable constraints on these findings.}, archive = {J_ApJ}, author = {L. A. C. van Son and S. K. Roy and I. Mandel and W. M. Farr and A. Lam and J. Merritt and F. S. Broekgaarden and A. A. C. Sander and J. J. Andrews}, doi = {10.3847/1538-4357/ada14a}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {209}, shortjournal = {The Astrophys. J.}, title = {Not just winds: Why models find that binary black hole formation is metallicity-dependent, while binary neutron star formation is not}, volume = {979}, year = {2025}, }
• (2025). A new approach to identifying red supergiant stars in metal-poor galaxies: A case study of NGC 6822. ApJ, 979(2), 208. (www)

  @article{ , abstract = {A complete sample of red supergiant (RSG) stars is important for studying their properties. Identifying RSGs in extragalactic fields first requires removing the Galactic foreground dwarfs. The color–color diagram (CCD) method, specifically using r − z / z − H and J − H / H − K , has proven successful in several studies. However, in metal-poor galaxies, faint RSGs will mix into the dwarf branch in the CCD and would be removed, leading to an incomplete RSG sample. This work attempts to improve the CCD method in combination with the Gaia astrometric measurement to remove foreground contamination in order to construct a complete RSG sample in metal-poor galaxies. The empirical regions of RSGs in both CCDs are defined and modified by fitting the locations of RSGs in galaxies with a range of metallicity. The metal-poor galaxy NGC 6822 is taken as a case study for its low metallicity ([Fe/H] ≈ −1.0) and moderate distance (about 500 kpc). In the complete sample, we identify 1184 RSG, 1559 oxygen-rich AGB (O-AGBs), 1075 carbon-rich AGB (C-AGBs), and 140 extreme AGB (x-AGBs) candidates, with a contamination rate of approximately 20.5%, 9.7%, 6.8%, and 5.0%, respectively. We also present a pure sample, containing only the sources away from the dwarf branch, which includes 843 RSG, 1519 O-AGB, 1059 C-AGB, and 140 x-AGB candidates, with a contamination rate of approximately 6.5%, 8.8%, 6.1%, and 5.0%, respectively. About 600 and 450 RSG candidates are newly identified in the complete and pure samples, respectively, compared to the previous RSG sample in NGC 6822.}, archive = {J_ApJ}, author = {Zhi-wen Li and Ming Yang and Biwei Jiang and Yi Ren}, doi = {10.3847/1538-4357/ada1d4}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {208}, shortjournal = {The Astrophys. J.}, title = {A new approach to identifying red supergiant stars in metal-poor galaxies: A case study of NGC 6822}, volume = {979}, year = {2025}, }
• (2025). Dynamics and energetics of resistive, thermally conductive, and radiative plasma in coronal current sheets due to asymmetric external perturbation. ApJ, 979(2), 207. (www)

  @article{ , abstract = {We study the asymmetric interaction of wave-like velocity perturbation with a coronal current sheet (CS) in the presence of resistivity, thermal conduction (TC), and radiative cooling (RC). We analyze the dynamics and energetics of the CS in four cases, namely, (i) no energy loss, (ii) TC only, (iii) RC only, and (iv) TC+RC. Before fragmentation, thinning and elongation of the CS are found to be identical in all four cases and therefore independent of the presence or absence of energy loss effects. Onset times, corresponding Lundquist numbers, and aspect ratios suggest that TC advances the onset of fragmentation while RC has the opposite effect in comparison to the absence of energy losses. Reconnection takes place at a higher rate in the presence of TC and TC+RC in the tearing unstable CS. Speeds of plasmoids are also found to be higher under the effect of TC and TC+RC. In the presence of TC and TC+RC, average density becomes higher within the tearing unstable CS than in the other two cases. As expected, the estimated average temperature is increasing with the highest and lowest rates in the absence of energy losses and in the presence of both TC and RC, respectively. After the onset of fragmentation, the rate of decrement of average magnetic energy density and increment of average kinetic energy density becomes higher in the presence of TC and TC+RC than in the other two cases. Thus, we conclude that the presence of energy-loss mechanisms critically influences the dynamics, energetics, and plasmoid formation within a reconnecting coronal CS.}, archive = {J_ApJ}, author = {Sripan Mondal and Akash Bairagi and A. K. Srivastava}, doi = {10.3847/1538-4357/ada1d6}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {207}, shortjournal = {The Astrophys. J.}, title = {Dynamics and energetics of resistive, thermally conductive, and radiative plasma in coronal current sheets due to asymmetric external perturbation}, volume = {979}, year = {2025}, }
• (2025). Nonthermal velocities in a solar active region observed by SERTS. ApJ, 979(2), 206. (www)

  @article{ , abstract = {We present measurements of coronal nonthermal Doppler velocities in NOAA Active Region 7870 observed by the Solar EUV Research Telescope and Spectrograph during its 1995 sounding rocket flight (SERTS-95). The instrument included a multilayer-coated toroidal diffraction grating that enhanced its sensitivity in second order at wavelengths between about 171 and 225 Å. Analyses of spectra from this flight were previously published but did not address the issue of nonthermal velocities; we do so here for spectra averaged over the 123 \mathop{.}\limits^{\unicode{x02033}} 8 segment of the slit for which the brightest portion of the region observed by SERTS was recorded. All emission lines are fit with Gaussian profiles. With post-flight laboratory spectra of He ii and Ne II-IIINe we derive a first-order instrumental width (full width at half-maximum intensity) of F inst ,1 = 50.6  ± 3.1 mÅ and a second-order instrumental width of F inst ,2 = 25.3 ±1.5 mÅ. For emission lines of Fe x −Fe xv , formed at 6.05 ≤ log T (K) ≤ 6.35, we find nonthermal velocities between 26.1 and 35.0 km s −1 , independent of temperature; this range corresponds to V nonth = 30.6 ± 4.5 km s −1 . For the two unblended Fe xii lines at 192.394 and 193.509 Å closest to the maximum sensitivity of SERTS-95, we have V nonth = 33.7  ± 1.3 km s −1 . When solar observations are used to derive or confirm instrumental widths for spectrometers in orbit, those observations should compensate for nonthermal velocities such as the ones reported here in order to extract instrumental widths that are free of nonthermal broadening.}, archive = {J_ApJ}, author = {Jeffrey W. Brosius}, doi = {10.3847/1538-4357/ada24d}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {206}, shortjournal = {The Astrophys. J.}, title = {Nonthermal velocities in a solar active region observed by SERTS}, volume = {979}, year = {2025}, }
• (2025). The hubble space telescope survey of m31 satellite galaxies. IV. survey overview and lifetime star formation histories. ApJ, 979(2), 205. (www)

  @article{ , abstract = {From >1000 orbits of HST imaging, we present deep homogeneous resolved star color–magnitude diagrams that reach the oldest main-sequence turnoff and uniformly measured star formation histories (SFHs) of 36 dwarf galaxies (−6 ≥ M V ≥ −17) associated with the M31 halo, and for 10 additional fields in M31, M33, and the Giant Stellar Stream. From our SFHs, we find: (i) The median stellar age and quenching epoch of M31 satellites correlate with galaxy luminosity and galactocentric distance. Satellite luminosity and present-day distance from M31 predict the satellite quenching epoch to within 1.8 Gyr at all epochs. This tight relationship highlights the fundamental connection between satellite halo mass, environmental history, and star formation duration. (ii) There is no difference between the median SFH of galaxies on and off the great plane of Andromeda satellites. (iii) ~50% of our M31 satellites show prominent ancient star formation (>12 Gyr ago) followed by delayed quenching (8–10 Gyr ago), which is not commonly observed among the MW satellites. (iv) A comparison with TNG50 and FIRE-2 simulated satellite dwarfs around M31-like hosts shows that some of these trends (dependence of SFH on satellite luminosity) are reproduced in the simulations while others (dependence of SFH on galactocentric distance, presence of the delayed-quenching population) are weaker or absent. We provide all photometric catalogs and SFHs as High-Level Science Products on MAST.}, archive = {J_ApJ}, author = {Alessandro Savino and Daniel R. Weisz and Andrew E. Dolphin and Meredith J. Durbin and Nitya Kallivayalil and Andrew Wetzel and Jay Anderson and Gurtina Besla and Michael Boylan-Kolchin and Thomas M. Brown and James S. Bullock and Andrew A. Cole and Michelle L. M. Collins and M. C. Cooper and Alis J. Deason and Aaron L. Dotter and Mark Fardal and Annette M. N. Ferguson and Tobias K. Fritz and Marla C. Geha and Karoline M. Gilbert and Puragra Guhathakurta and Rodrigo Ibata and Michael J. Irwin and Myoungwon Jeon and Evan N. Kirby and Geraint F. Lewis and Dougal Mackey and Steven R. Majewski and Nicolas Martin and Alan McConnachie and Ekta Patel and R. Michael Rich and Evan D. Skillman and Joshua D. Simon and Sangmo Tony Sohn and Erik J. Tollerud and Roeland P. van der Marel}, doi = {10.3847/1538-4357/ada24f}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {205}, shortjournal = {The Astrophys. J.}, title = {The hubble space telescope survey of m31 satellite galaxies. IV. survey overview and lifetime star formation histories}, volume = {979}, year = {2025}, }
• (2025). Ion charge states from a global time-dependent wave-turbulence-driven model of the solar wind: Comparison with in situ measurements. ApJ, 979(2), 204. (www)

  @article{ , abstract = {Solar wind charge-state measurements contain a wealth of knowledge related to the properties of the solar corona from where they originated. However, their interpretation has remained challenging because it convolves coronal temperature, density, and velocity along the particles' trajectory through the corona before they "freeze in" and are convected outward through the solar wind. In this study, we calculate ion charge states by coupling a nonequilibrium ionization model with a global magnetohydrodynamic model of the corona and inner heliosphere. We present results for two periods characteristic of solar minimum and maximum and compare them with observations from the ACE spacecraft. We find that the model reproduces the essential features of the observations, rectifying an earlier inconsistency that was apparent in 1D calculations, and allows us to unambiguously trace the evolution of charge states from the base of the corona into the solar wind.}, archive = {J_ApJ}, author = {Pete Riley and Roberto Lionello and Yeimy J. Rivera}, doi = {10.3847/1538-4357/ada253}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {204}, shortjournal = {The Astrophys. J.}, title = {Ion charge states from a global time-dependent wave-turbulence-driven model of the solar wind: Comparison with in situ measurements}, volume = {979}, year = {2025}, }
• (2025). Constraining solar emission radius at 42 MHz during the 2024 total solar eclipse using a student-commissioned radio telescope. ApJ, 979(2), 203. (www)

  @article{ , abstract = {Low-frequency solar radio emission is sourced in the solar corona, with sub-100 MHz radio emission largely originating from the ∼10 5 K plasma around 2 optical radii. However, the region of emission has yet to be constrained at 35–45 MHz due to both instrumentation limitations and the rarity of astronomical events, such as total solar eclipses, which allow for direct observational approaches. In this work, we present the results from a student-led project to commission a low-frequency radio telescope array situated in the path of totality of the 2024 total solar eclipse in an effort to probe the middle corona. The Deployable Low-Band Ionosphere and Transient Experiment (DLITE) is a low-frequency radio array comprised of four dipole antennas, optimized to observe at 35–45 MHz, and capable of resolving the brightest radio sources in the sky. We constructed a DLITE station in Observatory Park, a dark-sky park in Montville, Ohio. Results of observations during the total solar eclipse demonstrate that DLITE stations can be quickly deployed for observations and provide constraints on the radius of solar emission at our center observing frequency of 42 MHz. In this work, we outline the construction of DLITE Ohio and the solar observation results from the total solar eclipse that transversed North America in 2024 April.}, archive = {J_ApJ}, author = {Olivia R. Young and Timothy E. Dolch and Joseph F. Helmboldt and Christopher Mentrek and Louis P. Dartez and Michael T. Lam and Sophia V. Sosa Fiscella and Evan Bretl and Colin Joyce and Johannes Loock and Grace Meyer and Annabel Peltzer and Joseph Petullo and Parker Reed and Emerson Sigtryggsson and Benjamin Bassett and Andrew B. Hawken and Alejandro Z. Heredia and Paige Lettow and Whit Lewis and Mikayla Manna and Nicholas Mirochnikoff and Michael Zemcov}, doi = {10.3847/1538-4357/ada26e}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {203}, shortjournal = {The Astrophys. J.}, title = {Constraining solar emission radius at 42 MHz during the 2024 total solar eclipse using a student-commissioned radio telescope}, volume = {979}, year = {2025}, }
• (2025). Secular perturbations from exterior giants strongly influence gap complexity in peas-in-a-pod exoplanetary systems. ApJ, 979(2), 202. (www)

  @article{ , abstract = {It has been demonstrated that systems of tightly packed inner planets with giant exterior companions tend to have less regular orbital spacings than those without such companions. We investigate whether this observed increase in the gap complexity of the inner systems can be explained solely as the result of secular dynamics caused by the disturbing potential of the exterior companions. Amplification of mutual orbital inclinations in the inner system due to such secular dynamics may lead to the inner system attaining nonmutually transiting geometries, thereby creating artificial observed gaps that result in a higher calculated gap complexity. Using second-order secular theory, we compute time-averaged observed gap complexities along a favorable line of sight for a set of hypothetical systems, both with and without an outer giant. We find that these secular interactions can significantly contribute to the observed gap complexity dichotomy in tightly packed multiple-planet systems.}, archive = {J_ApJ}, author = {Joseph R. Livesey and Juliette Becker}, doi = {10.3847/1538-4357/ada28b}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {202}, shortjournal = {The Astrophys. J.}, title = {Secular perturbations from exterior giants strongly influence gap complexity in peas-in-a-pod exoplanetary systems}, volume = {979}, year = {2025}, }
• (2025). A new interpretation for the hot corona in active galactic nuclei. ApJ, 979(2), 201. (www)

  @article{ , abstract = {This work attempts to provide a new interpretation for the hot corona in active galactic nuclei (AGNs). A thin parabolic magnetic reconnection layer, anchored at the innermost disk and extending along the boundary of the magnetic tower for a few tens of gravitational radii, serves as a hard-X-ray source above the disk. Within this reconnection layer, the tearing instability leads to the formation of a chain of plasmoids, which contain relativistic electrons that generate X-ray radiation through inverse-Compton (IC) scattering of soft photons emitted by the accretion disk. Based on previous theoretical works and numerical simulations, we develop a heuristic framework to parameterize the geometry and magnetization of the reconnection layer, as well as to compute both the power of the IC-scattering radiation and the height of the reconnection layer. Our model allows for a quantitative investigation of the relation between the height of the corona and the X-ray radiation luminosity, which can be directly compared against the observed relation from X-ray reverberation mapping of individual AGNs. The theoretical results are in good agreement with the observations of IRAS 13224-3809, indicating the validation of our model.}, archive = {J_ApJ}, author = {Yu Zhao and Yan-Rong Li and Jian-Min Wang}, doi = {10.3847/1538-4357/ada35e}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {201}, shortjournal = {The Astrophys. J.}, title = {A new interpretation for the hot corona in active galactic nuclei}, volume = {979}, year = {2025}, }
• (2025). Ellipticities of galaxy cluster halos from Halo–Shear–Shear correlations. ApJ, 979(2), 200. (www)

  @article{ , abstract = {We report the first detection of the halo ellipticities of galaxy clusters by applying the halo–shear–shear correlations (HSSCs), without the necessity of using major axis determination. We use the Fourier_Quad shear catalog based on the Hyper Suprime-Cam Survey and the group catalog from the Dark Energy Spectroscopic Instrument Legacy Surveys for the measurement of group/cluster lensing and HSSC. Our analysis includes off-centering effects. We obtain the average projected ellipticity of dark matter halos with mass 13.5\lt {\rm{log}}({M}_{G}h/{M}_{\odot })\lt 14.5 within a 1.3 virial radius to be 0.4{8}_{-0.19}^{+0.12} . We divide the sample into two groups based on mass and redshift, and we find that halos with higher mass tend to exhibit increased ellipticity. We also reveal that high-richness halos have larger ellipticities, confirming the physical picture from numerical simulation that high-richness halos have a dynamical youth and more active mass accretion phase.}, archive = {J_ApJ}, author = {Zhenjie Liu and Jun Zhang and Cong Liu and Hekun Li}, doi = {10.3847/1538-4357/ada362}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {200}, shortjournal = {The Astrophys. J.}, title = {Ellipticities of galaxy cluster halos from Halo–Shear–Shear correlations}, volume = {979}, year = {2025}, }
• (2025). Bulk motions in the black hole jet sheath as a candidate for the comptonizing corona. ApJ, 979(2), 199. (www)

  @article{ , abstract = {Using two-dimensional general relativistic resistive magnetohydrodynamic simulations, we investigate the properties of the sheath separating the black hole jet from the surrounding medium. We find that the electromagnetic power flowing through the jet sheath is comparable to the overall accretion power of the black hole. The sheath is an important site of energy dissipation as revealed by the copious appearance of reconnection layers and plasmoid chains. About 20% of the sheath power is dissipated between 2 and 10 gravitational radii. The plasma in the dissipative sheath moves along a nearly paraboloidal surface with transrelativistic bulk motions dominated by the radial component, whose dimensionless 4-velocity is ∼1.2 ± 0.5. In the frame moving with the mean (radially dependent) velocity, the distribution of stochastic bulk motions resembles a Maxwellian with an "effective bulk temperature" of ∼100 keV. Scaling the global simulation to Cygnus X-1 parameters gives a rough estimate of the Thomson optical depth across the jet sheath, ∼0.01–0.1, and it may increase in future magnetohydrodynamic simulations with self-consistent radiative losses. These properties suggest that the dissipative jet sheath may be a viable "coronal" region, capable of upscattering seed soft photons into a hard, nonthermal tail, as seen during the hard states of X-ray binaries and active galactic nuclei.}, archive = {J_ApJ}, author = {Navin Sridhar and Bart Ripperda and Lorenzo Sironi and Jordy Davelaar and Andrei M. Beloborodov}, doi = {10.3847/1538-4357/ada385}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {199}, shortjournal = {The Astrophys. J.}, title = {Bulk motions in the black hole jet sheath as a candidate for the comptonizing corona}, volume = {979}, year = {2025}, }
• (2025). Inner-heliospheric signatures of steadily declining solar magnetic fields and their possible implications. ApJ, 979(2), 198. (www)

  @article{ , abstract = {We examined solar photospheric magnetic fields for the solar cycles 21–25, covering the period 1975–2024. The unsigned photospheric magnetic fields at low latitudes (0°–45°), known as solar toroidal fields, showed a solar cycle variation with the total field strength being stronger during the maximum of cycle 25 than the maximum of cycle 24. However, the unsigned field strength of photospheric magnetic fields at high latitudes (45°–78°), known as solar polar fields, has shown a significant steady decline since around the mid-1990s. The unsigned field strength of solar polar fields, after an increase during 2015–2020, has declined again until 2024, continuing the declining trend for a long 30 yr. Also, we examined the solar wind microturbulence levels in the inner heliosphere (0.2–0.8 au), using interplanetary scintillation observations at 327 MHz, covering the period 1983–2022, that steadily declined since the mid-1990s and continued until 2022, synchronously with the solar polar fields. We found that the floor level in both solar toroidal fields and solar wind magnetic fields was reduced during the minimum of cycle 23 and recovered back during the minimum of cycle 24. In addition, a hemispherically asymmetric solar polar reversal was evident in the signed (axial) solar polar fields during cycles 21–25, with the reversal in cycle 25 for the northern hemisphere already completed but the same for the southern hemisphere yet to be completed. We discuss the implications of the long declining trend and other anomalies in solar cycle activity.}, archive = {J_ApJ}, author = {Harsha Avinash Tanti and Susanta Kumar Bisoi and Abhirup Datta and K. Fujiki}, doi = {10.3847/1538-4357/ada38a}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {198}, shortjournal = {The Astrophys. J.}, title = {Inner-heliospheric signatures of steadily declining solar magnetic fields and their possible implications}, volume = {979}, year = {2025}, }
• (2025). Angular power spectrum of TeV–PeV cosmic-ray anisotropies. ApJ, 979(2), 197. (www)

  @article{ , abstract = {Simulations of the cosmic-ray (CR) anisotropy down to TeV energies are presented, using turbulence parameters consistent with those inferred from observations of the interstellar medium. We compute the angular power spectra C ℓ of the CR anisotropy obtained from the simulations. We demonstrate that the amplitude of the large-scale gradient in the CR density profile affects only the overall normalization of the C ℓ values, without affecting the shape of the angular power spectrum. We show that the power spectrum depends on CR energy and that it is sensitive to the location of the observer at small ℓ . It is found to flatten at large ℓ and can be modeled by a broken power law, exhibiting a break at ℓ ≈ 4. Our computed power spectrum at ~10 TeV fits well HAWC and IceCube measurements. Moreover, we calculate all coefficients of the spherical harmonics and compute the component of the angular power spectrum projected onto the direction of the local magnetic field line. We find that deviations from gyrotropy become increasingly important at higher CR energies and larger values of ℓ .}, archive = {J_ApJ}, author = {Wenyi Bian and Gwenael Giacinti and Brian Reville}, doi = {10.3847/1538-4357/ada441}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {197}, shortjournal = {The Astrophys. J.}, title = {Angular power spectrum of TeV–PeV cosmic-ray anisotropies}, volume = {979}, year = {2025}, }
• (2025). Pulsar scattering as a probe for structures in the interstellar medium. ApJ, 979(2), 196. (www)

  @article{ , abstract = {Due to the inhomogeneity of electron number density, radio waves emitted by pulsars undergo scattering as they pass through the interstellar medium (ISM). However, a connection between large-scale pulsar scattering data and the structure of the Galactic ISM has yet to be established. In this paper, we explore the capability of pulsar scattering time data in discovering structures in the ISM. Using a large data set of scattering time measurements for 473 pulsars, we fit the pulsar reduced scattering intensity as a function of Galactic latitude and distance, constructing a smooth model of the Galactic pulsar scattering distribution. By comparing this smooth distribution with observational data, we identify two ISM structures responsible for pulsar scattering, one is associated with the Vela supernova remnant region within the Gum Nebula, while the other is a newly discovered structure—a distant superbubble, G38, located at a distance of 2.3 kpc with a size of ~50 pc. Analysis of the correlation coefficient of the pulsar scattering distribution shows that the correlation is dominated by structures smaller than 0.15 kpc—the closest separation approachable by the current data set. As measurements of the pulsar scattering time continue to increase in the future, they can potentially become an independent tool for exploring structures in the ISM.}, archive = {J_ApJ}, author = {Qiuyi He and Xun Shi and Guangxing Li}, doi = {10.3847/1538-4357/ada4af}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {196}, shortjournal = {The Astrophys. J.}, title = {Pulsar scattering as a probe for structures in the interstellar medium}, volume = {979}, year = {2025}, }
• (2025). Ubiquitous small-scale extreme-ultraviolet upflow-like events above network regions observed by the solar Orbiter/Extreme ultraviolet imager. ApJ, 979(2), 195. (www)

  @article{ , abstract = {Universal small-scale solar activity in the quiet region is suggested to be a potential source of solar wind and the upper solar atmosphere. Here, with the high-resolution 174 Å imaging observations from the Solar Orbiter/Extreme Ultraviolet Imager, we investigate 59 EUV upflow-like events observed in the quiet Sun. Their average apparent (plane-of-sky) velocity, lifetime, and propagation distance are measured as 62 km s −1 , 68.6 s, and 3.94 Mm, respectively. These upflow-like events exhibit dynamic characteristics but lack base brightening, featuring a hot front and subsequent cold plasma ejection. A total of 39% of the EUV upflow-like events exhibit recurrent characteristics. Unprecedented high-resolution 174 Å observations reveal that some EUV upflow-like events exhibit blob-like fine structures and multistrand evolutionary features, and some upflow-like events can cause localized haze-like plasma heating ahead of their spire region during the ejection process. A subset of the EUV upflow-like events covered by the Solar Dynamics Observatory reveals that they appear at the chromospheric networks. Through emission measure analysis, we found that these upflow-like events eject hot plasma of transient region or coronal temperature (an average of ~10 5.5 K). We suggest that EUV upflow-like events may be EUV counterparts of chromospheric spicules and/or transition region network jets and play a role in heating the localized corona above the network regions.}, archive = {J_ApJ}, author = {Yadan Duan and Hechao Chen and Zhenyong Hou and Zheng Sun and Yuandeng Shen}, doi = {10.3847/1538-4357/ada556}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {195}, shortjournal = {The Astrophys. J.}, title = {Ubiquitous small-scale extreme-ultraviolet upflow-like events above network regions observed by the solar Orbiter/Extreme ultraviolet imager}, volume = {979}, year = {2025}, }
• (2025). High-energy neutrino source cross-correlations with nearest-neighbor distributions. ApJ, 979(2), 194. (www)

  @article{ , abstract = {The astrophysical origins of the majority of the IceCube neutrinos remain unknown. Effectively characterizing the spatial distribution of the neutrino samples and associating the events with astrophysical source catalogs can be challenging given the large atmospheric neutrino background and underlying non-Gaussian spatial features in the neutrino and source samples. In this paper, we investigate a framework for identifying and statistically evaluating the cross-correlations between IceCube data and an astrophysical source catalog based on the k -nearest-neighbor cumulative distribution functions ( k NN-CDFs). We propose a maximum likelihood estimation procedure for inferring the true proportions of astrophysical neutrinos in the point-source data. We conduct a statistical power analysis of an associated likelihood ratio test with estimations of its sensitivity and discovery potential with synthetic neutrino data samples and a WISE–2MASS galaxy sample. We apply the method to IceCube's public ten-year point-source data and find no statistically significant evidence for spatial cross-correlations with the selected galaxy sample. We discuss possible extensions to the current method and explore the method's potential to identify the cross-correlation signals in data sets with different sample sizes.}, archive = {J_ApJ}, author = {Zhuoyang Zhou and Jessi Cisewski-Kehe and Ke Fang and Arka Banerjee}, doi = {10.3847/1538-4357/ad924c}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {194}, shortjournal = {The Astrophys. J.}, title = {High-energy neutrino source cross-correlations with nearest-neighbor distributions}, volume = {979}, year = {2025}, }
• (2025). CEERS: Increasing scatter along the star-forming main sequence indicates early galaxies form in bursts. ApJ, 979(2), 193. (www)

  @article{ , abstract = {We present the star formation rate–stellar mass (SFR– M * ) relation for galaxies in the Cosmic Evolution Early Release Science survey at 4.5 ≤ z ≤ 12. We model the JWST and Hubble Space Telescope rest-UV and rest-optical photometry of galaxies with flexible star formation histories (SFHs) using BAGPIPES. We consider SFRs averaged from the SFHs over 10 Myr (SFR 10 ) and 100 Myr (SFR 100 ), where the photometry probes SFRs on these timescales, effectively tracing nebular emission lines in the rest-optical (on  ~10 Myr timescales) and the UV/optical continuum (on  ~100 Myr timescales). We measure the slope, normalization and intrinsic scatter of the SFR– M * relation, taking into account the uncertainty and the covariance of galaxy SFRs and M * . From z ~ 5 to 9 there is larger scatter in the SFR 10 – M * relation, with \sigma (\mathrm{log}{\rm{S}}{\rm{F}}{{\rm{R}}}_{100})=0.4 dex, compared to the SFR 100 – M * relation, with \sigma (\mathrm{log}SF{R}_{10})=0.1 dex. This scatter increases with redshift and increasing stellar mass, at least out to z ~ 7. These results can be explained if galaxies at higher redshift experience an increase in star formation variability and form primarily in short, active periods, followed by a lull in star formation (i.e., "napping" phases). We see a significant trend in the ratio R SFR = SFR 10 /SFR 100 in which, on average, R SFR decreases with increasing stellar mass and increasing redshift. This yields a star formation "duty cycle" of ~40% for galaxies with \mathrm{log}{M}_{* }/{M}_{\odot }\geqslant 9.3 at z ~ 5, declining to ~20% at z ~ 9. Galaxies also experience longer lulls in star formation at higher redshift and at higher stellar mass, such that galaxies transition from periods of higher SFR variability at z ≳ 6 to smoother SFR evolution at z ≲ 4.5.}, archive = {J_ApJ}, author = {Justin W. Cole and Casey Papovich and Steven L. Finkelstein and Micaela B. Bagley and Mark Dickinson and Kartheik G. Iyer and L. Y. Aaron Yung and Laure Ciesla and Ricardo O. Amorín and Pablo Arrabal Haro and Rachana Bhatawdekar and Antonello Calabrò and Nikko J. Cleri and Alexander de la Vega and Avishai Dekel and Ryan Endsley and Eric Gawiser and Mauro Giavalisco and Nimish P. Hathi and Michaela Hirschmann and Benne W. Holwerda and Jeyhan S. Kartaltepe and Anton M. Koekemoer and Ray A. Lucas and Sara Mascia and Bahram Mobasher and Pablo G. Pérez-González and Giulia Rodighiero and Kaila Ronayne and Sandro Tacchella and Benjamin J. Weiner and Stephen M. Wilkins}, doi = {10.3847/1538-4357/ad9a6a}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {193}, shortjournal = {The Astrophys. J.}, title = {CEERS: Increasing scatter along the star-forming main sequence indicates early galaxies form in bursts}, volume = {979}, year = {2025}, }
• (2025). Extreme scale height variations and nozzle shocks in warped disks. ApJ, 979(2), 192. (www)

  @article{ , abstract = {Accretion disks around both stellar-mass and supermassive black holes (BHs) are likely often warped. Whenever a disk is warped, its scale height varies with azimuth. Sufficiently strong warps cause extreme compressions of the scale height, which fluid parcels "bounce" off of twice per orbit to high latitudes. We study the dynamics of strong warps using (i) the nearly analytic "ring theory" of Fairbairn & Ogilvie, which we generalize to the Kerr metric, and (ii) three-dimensional general-relativistic hydrodynamic simulations of tori ("rings") around BHs, using the H-AMR code. We initialize a ring with a warp and study its evolution on tens of orbital periods. The simulations agree excellently with the ring theory until the warp amplitude, ψ , reaches a critical value ψ c . When ψ > ψ c , the rings enter the bouncing regime. We analytically derive (and numerically validate) that {\psi }_{{\rm{c}}}\approx {(r/{r}_{{\rm{g}}})}^{-1/2} in the non-Keplerian regime, where r g = GM / c 2 is the gravitational radius, and M is the mass of the central object. Whenever the scale height bounces, the vertical velocity becomes supersonic, leading to "nozzle shocks" as gas collides at the scale height minima. Nozzle shocks damp the warp within ≈10–20 orbits, which is not captured by the ring theory. Nozzle shock dissipation leads to inflow timescales 1–2 orders of magnitude shorter than unwarped α disks, which may result in rapid variability, such as in changing-look active galactic nuclei or in the soft state of X-ray binaries. We propose that steady disks with strong warps may self-regulate to have amplitudes near ψ c .}, archive = {J_ApJ}, author = {Nicholas Kaaz and Yoram Lithwick and Matthew Liska and Alexander Tchekhovskoy}, doi = {10.3847/1538-4357/ad9a85}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {192}, shortjournal = {The Astrophys. J.}, title = {Extreme scale height variations and nozzle shocks in warped disks}, volume = {979}, year = {2025}, }
• (2025). Impacts and statistical mitigation of missing data on the 21 cm power spectrum: A case study with the hydrogen epoch of reionization array. ApJ, 979(2), 191. (www)

  @article{ , abstract = {The precise characterization and mitigation of systematic effects is one of the biggest roadblocks impeding the detection of the fluctuations of cosmological 21 cm signals. Missing data in radio cosmological experiments, often due to radio frequency interference (RFI), pose a particular challenge to power spectrum analysis as this could lead to the ringing of bright foreground modes in the Fourier space, heavily contaminating the cosmological signals. Here we show that the problem of missing data becomes even more arduous in the presence of systematic effects. Using a realistic numerical simulation, we demonstrate that partially flagged data combined with systematic effects can introduce significant foreground ringing. We show that such an effect can be mitigated through inpainting the missing data. We present a rigorous statistical framework that incorporates the process of inpainting missing data into a quadratic estimator of the 21 cm power spectrum. Under this framework, the uncertainties associated with our inpainting method and its impact on power spectrum statistics can be understood. These results are applied to the latest Phase II observations taken by the Hydrogen Epoch of Reionization Array, forming a crucial component in power spectrum analyses as we move toward detecting 21 cm signals in the ever more noisy RFI environment.}, archive = {J_ApJ}, author = {Kai-Feng Chen and Michael J. Wilensky and Adrian Liu and Joshua S. Dillon and Jacqueline N. Hewitt and Tyrone Adams and James E. Aguirre and Rushelle Baartman and Adam P. Beardsley and Lindsay M. Berkhout and Gianni Bernardi and Tashalee S. Billings and Judd D. Bowman and Philip Bull and Jacob Burba and Ruby Byrne and Steven Carey and Samir Choudhuri and Tyler Cox and David. R. DeBoer and Matt Dexter and Nico Eksteen and John Ely and Aaron Ewall-Wice and Steven R. Furlanetto and Kingsley Gale-Sides and Hugh Garsden and Bharat Kumar Gehlot and Adélie Gorce and Deepthi Gorthi and Ziyaad Halday and Bryna J. Hazelton and Jack Hickish and Daniel C. Jacobs and Alec Josaitis and Nicholas S. Kern and Joshua Kerrigan and Piyanat Kittiwisit and Matthew Kolopanis and Paul La Plante and Adam Lanman and Yin-Zhe Ma and David H. E. MacMahon and Lourence Malan and Cresshim Malgas and Keith Malgas and Bradley Marero and Zachary E. Martinot and Lisa McBride and Andrei Mesinger and Nicel Mohamed-Hinds and Mathakane Molewa and Miguel F. Morales and Steven G. Murray and Hans Nuwegeld and Aaron R. Parsons and Robert Pascua and Yuxiang Qin and Eleanor Rath and Nima Razavi-Ghods and James Robnett and Mario G. Santos and Peter Sims and Saurabh Singh and Dara Storer and Hilton Swarts and Jianrong Tan and Pieter van Wyngaarden and Haoxuan Zheng}, doi = {10.3847/1538-4357/ad9b91}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {191}, shortjournal = {The Astrophys. J.}, title = {Impacts and statistical mitigation of missing data on the 21 cm power spectrum: A case study with the hydrogen epoch of reionization array}, volume = {979}, year = {2025}, }
• (2025). Uniform modeling of observed kilonovae: Implications for diversity and the progenitors of merger-driven long gamma-ray bursts. ApJ, 979(2), 190. (www)

  @article{ , abstract = {We present uniform modeling of eight kilonovae, five following short gamma-ray bursts (GRBs; including GRB 170817A) and three following long GRBs. We model their broadband afterglows to determine the relative contributions of afterglow and kilonova emission. We fit the kilonovae using a three-component model in MOSFiT , and report population median ejecta masses for the total, blue ( κ B = 0.5 cm 2 g −1 ), purple ( κ P = 3 cm 2 g −1 ), and red ( κ R = 10 cm 2 g −1 ) components. The kilonova of GW170817 is near the sample median in most derived properties. We investigate trends between the ejecta masses and the isotropic-equivalent and beaming-corrected γ -ray energies ( E γ ,iso , E γ ), as well as rest-frame durations ( T 90,rest ). We find long GRB kilonovae have higher median red ejecta masses ( M ej,R ≳ 0.05 M ⊙ ) compared to on-axis short GRB kilonovae ( M ej,R ≲ 0.02 M ⊙ ). We also observe a weak scaling between the total and red ejecta masses with E γ ,iso and E γ , though a larger sample is needed to establish a significant correlation. These findings imply a connection between merger-driven long GRBs and larger tidal dynamical ejecta masses, which may indicate that their progenitors are asymmetric compact object binaries. We produce representative kilonova light curves, and find that the planned depths and cadences of the Rubin and Roman Observatory surveys will be sufficient for order-of-magnitude constraints on M ej,B (and, for Roman, M ej,P and M ej,R ) of future kilonovae at z ≲ 0.1.}, archive = {J_ApJ}, author = {J. C. Rastinejad and W. Fong and C. D. Kilpatrick and M. Nicholl and B. D. Metzger}, doi = {10.3847/1538-4357/ad9c77}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {190}, shortjournal = {The Astrophys. J.}, title = {Uniform modeling of observed kilonovae: Implications for diversity and the progenitors of merger-driven long gamma-ray bursts}, volume = {979}, year = {2025}, }
• (2025). The observed phase space of mass-loss history from massive stars based on radio observations of a large supernova sample. ApJ, 979(2), 189. (www)

  @article{ , abstract = {In this work, we study the circumstellar material (CSM) around massive stars, and the mass-loss rates depositing this CSM, using a large sample of radio observations of 325 core-collapse supernovae (CCSNe; only ~22% of them being detected). This sample comprises both archival data and our new observations of 99 CCSNe conducted with the AMI-LA radio array in a systematic approach devised to constrain the mass loss at different stages of stellar evolution. In the supernova (SN)–CSM interaction model, observing the peak of the radio emission of an SN provides the CSM density at a given radius (and therefore the mass-loss rate that deposited this CSM). On the other hand, limits on the radio emission, and/or on the peak of the radio emission provide a region in the CSM phase space that can be ruled out. Our analysis shows a discrepancy between the values of mass-loss rates derived from radio-detected and radio-nondetected SNe. Furthermore, we rule out mass-loss rates in the range of 2 × 10 −6 –10 −4 M ⊙ yr −1 for different epochs during the last 1000 yr before the explosion (assuming wind velocity of 10 km s −1 ) for the progenitors of ~80% of the Type II supernovae (SNe II) in our sample. In addition, we rule out the ranges of mass-loss rates suggested for red supergiants for ~50% of the progenitors of SNe II in our sample. We emphasize here that these results take a step forward in constraining mass loss in winds from a statistical point of view.}, archive = {J_ApJ}, author = {Itai Sfaradi and Assaf Horesh and Rob Fender and Lauren Rhodes and Joe Bright and David Williams-Baldwin and Dave A. Green}, doi = {10.3847/1538-4357/ad9e93}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {189}, shortjournal = {The Astrophys. J.}, title = {The observed phase space of mass-loss history from massive stars based on radio observations of a large supernova sample}, volume = {979}, year = {2025}, }
• (2025). Jetted seyfert galaxies at z = 0: Simulating feedback effects on galactic morphology and beyond. ApJ, 979(2), 188. (www)

  @article{ , abstract = {We use high-resolution cosmological zoom-in simulations to model feedback from Seyfert-type supermassive black hole (SMBH) jets onto galaxies with identical dark matter (DM) halos of log M / M ⊙ ∼ 11.8. The low-mass,  ∼10 6 M ⊙ , seed SMBHs have been introduced when the parent DM halos have reached log M / M ⊙ ∼ 11. In a controlled experiment, we vary only the efficiency of the SMBH accretion and focus on galaxies and their immediate environment properties. Our results show that the active galactic nucleus jet feedback has a substantial effect on the basic properties of Seyfert-type galaxies, such as morphology, gas fraction and distribution, star formation rate and distribution, B/D ratio, DM halo baryon fraction, and properties of the circumgalactic medium and beyond. These have been compared to a galaxy with supernovae only feedback. We focus on the energy deposition by the jet in the interstellar medium (ISM) and intergalactic gas medium, and follow the expansion of the multiple jet cocoons to ∼2 Mpc. We find that the jet–ISM interaction gradually pushes the star formation to larger radii with increasing accretion efficiency, which results in increased mass of the outer stellar disk, which is best fit as a double-exponential disk. Furthermore, we compare our galaxies and their properties with the observed nearby Seyfert galaxies, including the scaling relations, and find a close agreement, although statistical analysis of observed Seyferts is currently missing. In a forthcoming paper, we focus on the evolution of these objects at z ≲ 10 and study the effect of the SMBH seeding redshift.}, archive = {J_ApJ}, author = {Julianne Goddard and Isaac Shlosman and Emilio Romano-Diaz}, doi = {10.3847/1538-4357/ad9f29}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {188}, shortjournal = {The Astrophys. J.}, title = {Jetted seyfert galaxies at z = 0: Simulating feedback effects on galactic morphology and beyond}, volume = {979}, year = {2025}, }
• (2025). Study of satellite plane structure characteristics based on TNG50 simulations: A comparative analysis from plane to nonplane structures. ApJ, 979(2), 187. (www)

  @article{ , abstract = {In recent years, multiple plane structures of satellite galaxies have been identified in the nearby Universe, although their formation mechanisms remain unclear. In this work, we employ the TNG50-1 numerical simulation to classify satellite systems into plane and nonplane structures, based on their geometric and dynamical properties. We focus on comparing the characteristics of these plane and nonplane structures. The plane structures in TNG50-1 exhibit a mean height of 5.24 kpc, with most of them found in galaxy groups with intermediate halo virial masses within the narrow range of 10 11.5 –10 12.5 M ⊙ . Statistical analyses reveal that plane structures of satellite galaxies constitute approximately 11.30% in TNG50-1, with this proportion increasing to 27.11% in TNG100-1, aligning closely with previous observations. Additionally, central galaxies in clusters and groups hosting corotating plane structures are intermediate massive and slightly metal-poorer than those in nonplane structures. Significant differences are found between in-plane and out-of-plane satellite galaxies, suggesting that in-plane satellites exhibit slightly longer formation times and more active interstellar matter cycles. The satellites within these plane structures in TNG50-1 exhibit similar radial distributions with observations but are fainter and more massive than those in observational plane structures due to the over- or underestimation of galaxy properties in simulations. Our analysis also shows that the satellite plane structures might be affected by some low- or high-mass galaxies temporarily entering the plane structures due to the gravitational potential of the clusters and groups after the plane structures had formed.}, archive = {J_ApJ}, author = {Caiyu Hu and Lin Tang}, doi = {10.3847/1538-4357/ad9f34}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {187}, shortjournal = {The Astrophys. J.}, title = {Study of satellite plane structure characteristics based on TNG50 simulations: A comparative analysis from plane to nonplane structures}, volume = {979}, year = {2025}, }
• (2025). Study on the shallow decay segment of gamma-ray burst X-ray afterglow. ApJ, 979(2), 186. (www)

  @article{ , abstract = {The X-ray afterglow of a certain fraction of gamma-ray bursts (GRBs) comprises a phase of shallow decay. However, the origin of the shallow decay segment is still a mystery. In this paper, we select 103 GRBs that exhibit a shallow decay segment, based on Swift/XRT data prior to 2023 June. We apply the fallback accretion energy external dissipation model to the shallow decay segment in our sample, and find the model can interpret the shallow decay segment within a reasonable range of parameter space. The fallback rate of the progenitor envelope materials onto the accretion disk can reach a peak of 10 −7 –0.1 M ⊙ s −1 within a time frame of 10–10 5 s, which is consistent with the typical density profile and spin profile of the progenitor of a GRB. During the fallback process of progenitor envelope materials, progenitor stars of most GRBs have the highest fallback rate at a radius ~10 10 cm, which is consistent with the typical radius of a Wolf–Rayet star. The production of shallow decay segments of most GRBs in our sample requires injecting Blandford–Znajek (BZ) energy equal to 10–100 times the kinetic energy of the initial GRB blast wave into the blast wave. However, the shallow decay segment of a few GRBs requires the injected energy to be comparable to the kinetic energy of the blast wave, which means that even if less energy is injected into a GRB blast wave, it is still possible to produce a shallow decay segment. In addition, the peak time of the fallback rate of the progenitor envelope materials is close to the time when BZ energy is injected into the blast wave, which means that the fallback accretion is more active in the initial phase. In summary, our research results provide further support to an external origin for the shallow decay segment in GRBs.}, archive = {J_ApJ}, author = {Litao Zhao and Minjiang Chen and Fan Wu and Yang Liu and Xuqing Wang and Yuxin Wang}, doi = {10.3847/1538-4357/ada0b9}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {186}, shortjournal = {The Astrophys. J.}, title = {Study on the shallow decay segment of gamma-ray burst X-ray afterglow}, volume = {979}, year = {2025}, }
• (2025). Streaming torque with turbulent diffusion. ApJ, 979(2), 185. (www)

  @article{ , abstract = {Fast type I migration of (proto)planets poses a challenging problem for the core accretion formation scenario. We found that the dust-induced "Streaming Torque" (ST) may slow down or even reverse the planet migration in Q. Hou & C. Yu. But in realistic protoplanetary disks, dust diffusion induced by gas turbulence may have important influences on ST. We perform linear analysis to investigate the effects of dust diffusion on ST. The dependence of ST on dust diffusion may provide better constraints on the turbulence strength and the stopping time τ . We derive the dispersion relation for all the wave modes in the two-fluid system. The dust diffusion will smooth the short-wavelength structure of the the quasi-drift mode and split it into two predominant D-drift modes with opposite directions. The outgoing D-drift mode will contribute to a negative torque on planets, particularly when τ ∼ 0.1, which slightly shifts the zero-torque turning point. We explore how ST depends on the regimes of aerodynamic drag, dust mass fraction, and disk scale height. We compare the radial wavenumbers of D-drift modes under different formulations of dust diffusion and find qualitative agreement. In all cases, τ at the zero-torque turning point, which determines the direction of planetary migration, consistently remains on the order of ∼0.1, corresponding to large pebble-sized dust grains. This suggests that rapid dust coagulation can inhibit the inward migration of planets, implying that weak gas turbulence may enhance the survival of protoplanets.}, archive = {J_ApJ}, author = {Qiang Hou and Cong Yu}, doi = {10.3847/1538-4357/ada15a}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {185}, shortjournal = {The Astrophys. J.}, title = {Streaming torque with turbulent diffusion}, volume = {979}, year = {2025}, }
• (2025). COOL-LAMPS. VII. quantifying strong-lens scaling relations with 177 cluster-scale strong gravitational lenses in DECaLS. ApJ, 979(2), 184. (www)

  @article{ , abstract = {We estimate the Einstein-radius-enclosed total mass for 177 cluster-scale strong gravitational lenses identified by the ChicagO Optically selected Lenses Located At the Margins of Public Surveys (COOL-LAMPS) collaboration with lens redshifts ranging from 0.2 ⪅ z ⪅ 1.0 using the brightest-cluster-galaxy (BCG) redshift and an observable proxy for the Einstein radius. We constrain the Einstein-radius-enclosed luminosity and stellar mass by fitting parametric spectral energy distributions to aperture photometry from the Dark Energy Camera Legacy Survey (DECaLS) in the g -, r -, and z -band Dark Energy Camera filters. We find that the BCG redshift, enclosed total mass, and enclosed luminosity are strongly correlated and well described by a planar relationship in 3D space. We find that the enclosed total mass and stellar mass are correlated with a logarithmic slope of 0.50{0}_{-0.031}^{+0.029} , and the enclosed total mass and stellar-to-total mass fraction are correlated with a logarithmic slope of -0.49{5}_{-0.033}^{+0.032} . In tandem with the small radii within which these slopes are constrained, this may suggest invariance in baryon conversion efficiency and feedback strength as a function of cluster-centric radii in galaxy clusters. Additionally, the correlations described here should have utility in ranking strong-lensing candidates in upcoming imaging surveys—such as Rubin/Legacy Survey of Space and Time—in which an algorithmic treatment of strong lenses will be needed due to the sheer volume of data these surveys will produce.}, archive = {J_ApJ}, author = {Simon D. Mork and Michael D. Gladders and Gourav Khullar and Keren Sharon and Nathalie Chicoine and Aidan P. Cloonan and Håkon Dahle and Diego Garza and Rowen Glusman and Katya Gozman and Gabriela Horwath and Benjamin C. Levine and Olina Liang and Daniel Mahronic and Viraj Manwadkar and Michael N. Martinez and Alexandra Masegian and Owen S. Matthews Acuña and Kaiya Merz and Yue Pan and Jorge A. Sanchez and Isaac Sierra and Daniel J. Kavin Stein and Ezra Sukay and Marcos Tamargo-Arizmendi and Kiyan Tavangar and Ruoyang Tu and Grace Wagner and Erik A. Zaborowski and Yunchong Zhang and (COOL-LAMPS Collaboration)}, doi = {10.3847/1538-4357/ada24c}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {184}, shortjournal = {The Astrophys. J.}, title = {COOL-LAMPS. VII. quantifying strong-lens scaling relations with 177 cluster-scale strong gravitational lenses in DECaLS}, volume = {979}, year = {2025}, }
• (2025). Subaru high-z exploration of low-luminosity quasars (SHELLQs). XXI. candidate red quasars at z ≥ 6 from near-infrared photometry. ApJ, 979(2), 183. (www)

  @article{ , abstract = {We present an analysis of near-infrared photometry of 59 quasars at 5.83 < z < 7.07, obtained with the Gemini North Telescope and the Gran Telescopio CANARIAS. The sample consists of low-luminosity quasars discovered in the Subaru High- z Exploration of Low-Luminosity Quasars (SHELLQs) project. With the near-infrared magnitudes combined with the optical photometric and spectroscopic data from the previous Hyper Suprime-Cam and SHELLQs observations, we searched for red (dust-reddened) quasars, characterized by the color excess of E ( B − V ) > 0.1. We identified five red quasar candidates. The low fraction (8%) of red quasars in our sample suggests that the low luminosity of the SHELLQs quasars is mostly due to the nature of the quasars, not due to extinction by dust. The candidates tend to be found on the low-luminosity side (measured with the rest-ultraviolet absolute magnitude at 1450 Å of M 1450 > −24 mag) of the sample. This luminosity trend may support the idea that red quasars represent an evolutionary stage preceding unobscured quasars, often invoked in the merger-driven galaxy evolution scenario.}, archive = {J_ApJ}, author = {Ryo Iwamoto and Yoshiki Matsuoka and Masatoshi Imanishi and Kazushi Iwasawa and Takuma Izumi and Nobunari Kashikawa and Toshihiro Kawaguchi and Mahoshi Sawamura and Michael A. Strauss and Ayumi Takahashi and Yoshiki Toba}, doi = {10.3847/1538-4357/ada27b}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {183}, shortjournal = {The Astrophys. J.}, title = {Subaru high-z exploration of low-luminosity quasars (SHELLQs). XXI. candidate red quasars at z ≥ 6 from near-infrared photometry}, volume = {979}, year = {2025}, }
• (2025). Magnetic reconnection between a solar jet and a filament channel. ApJ, 979(2), 182. (www)

  @article{ , abstract = {The solar corona is highly structured by bunches of magnetic field lines forming either loops, or twisted flux ropes representing prominences/filaments, or very dynamic structures such as jets. The aim of this paper is to understand the interaction between filament channels and jets. We use high-resolution H α spectra obtained by the ground-based telescope Télescope Héliographique pour l'Etude du Magnétisme et des Instabilités Solaires on the Canary Islands and data from Helioseismic Magnetic Imager and Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory. In this paper we present a multiwavelength study of the interaction of filaments and jets. They both consist of cool plasma embedded in magnetic structures. A jet is particularly well studied in all the AIA channels with a flow reaching 100–180 km s −1 . Its origin is linked to cancelling flux at the edge of the active region. Large Doppler shifts in H α are derived in a typical area for a short time (order of minute). They correspond to flows around 140 km s −1 . In conclusion we conjecture that these flows correspond to some interchange of magnetic field lines between the filament channel and the jets leading to cool plasmoid ejections or reconnection jets perpendicularly to the jet trajectory.}, archive = {J_ApJ}, author = {Garima Karki and Brigitte Schmieder and Pooja Devi and Ramesh Chandra and Nicolas Labrosse and Reetika Joshi and Bernard Gelly}, doi = {10.3847/1538-4357/ada28e}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {182}, shortjournal = {The Astrophys. J.}, title = {Magnetic reconnection between a solar jet and a filament channel}, volume = {979}, year = {2025}, }
• (2025). Discrepancies between JWST observations and simulations of quenched massive galaxies at z > 3: A comparative study with IllustrisTNG and ASTRID. ApJ, 979(2), 181. (www)

  @article{ , abstract = {Recent JWST observations have uncovered an unexpectedly large population of massive quiescent galaxies at z > 3. Using the cosmological simulations IllustrisTNG and ASTRID , we identify analogous galaxies and investigate their abundance, formation, quenching mechanisms, and post-quenching evolution for stellar masses 9.5\lt {\mathrm{log}}_{10}({M}_{\star }/{M}_{{\odot }})\lt 12 . We apply three different quenching definitions and find that both simulations significantly underestimate the comoving number density of quenched massive galaxies at z ≳ 3 compared to JWST observations by up to ∼2 dex. In both simulations, the high- z quenched massive galaxies often host overmassive central black holes above the local M BH – M ⋆ relation, implying that AGN feedback is key in quenching galaxies in the early Universe. The typical quenching timescales for these galaxies are ∼200–600 Myr. IllustrisTNG primarily employs AGN kinetic feedback, while ASTRID relies on AGN thermal feedback at z > 2.3, which is less effective and has a longer quenching timescale. Although these simulations differ in many aspects, making a direct comparison challenging, our findings suggest the need for improved physical models of AGN feedback in galaxy formation simulations. At lower stellar masses, the quenched galaxies have denser local environments than the star-forming galaxies, suggesting that environmental quenching helps quench less-massive galaxies. We also study the post-quenching evolution of the high- z massive quiescent galaxies and find that many experience subsequent reactivation of star formation, evolving into primary progenitors of z = 0 brightest cluster galaxies.}, archive = {J_ApJ}, author = {Emma Jane Weller and Fabio Pacucci and Yueying Ni and Lars Hernquist and Minjung Park}, doi = {10.3847/1538-4357/ada360}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {181}, shortjournal = {The Astrophys. J.}, title = {Discrepancies between JWST observations and simulations of quenched massive galaxies at z > 3: A comparative study with IllustrisTNG and ASTRID}, volume = {979}, year = {2025}, }
• (2025). Multiple episodes of remote brightenings driven by a coronal extreme-ultraviolet jet on the sun. ApJ, 979(2), 180. (www)

  @article{ , abstract = {Remote brightening (RB) is compact brightening at footpoints of magnetic loops, which are remotely connecting to and confining an eruption in the solar atmosphere. Here, we report on observations of an RB resulting from an EUV jet with a speed of about 90 km s −1 . The loops connecting the RB and the jet have an apparent length of about 59 Mm. Intriguingly, the RB exhibits at least two episodes of brightenings, as characterized by two peaks in its lightcurve. The energies that sustain the first and second peaks of the RB are 6.3 × 10 26 erg and 8.4 × 10 26 erg, respectively, and comprise a significant proportion of the total energy. The first peak of the RB brightenings coincides with the jet's peak with a time delay of 12 s, while the second peak lags behind by 108 s. Besides the flows of the ejecta, we have identified two additional flows originating from the eruption site. One is relatively cool with a temperature of {{\rm{log}}}_{10}(T/{\rm{K}})=5.8 –6.1 and a speed of about 275 ± 15 km s −1 . The other is hot with a temperature of {{\rm{log}}}_{10}(T/{\rm{K}})=7.0 –7.3 and a much greater speed of about 750 ± 70 km s −1 . We attribute the second peak of RB directly to this hot flow, which our numerical experiments suggest is the result of a slow shock wave. Considering the minimal time delay between the first peak of RB and the eruption, we infer that this first episode is due to heating by nonthermal electrons. Our research demonstrates that the dynamics in an RB can offer vital insights into the nature of the corresponding eruption and help understand how energy is distributed throughout the solar atmosphere.}, archive = {J_ApJ}, author = {Chao Zhang and Zhenghua Huang and Hengyuan Wei and Youqian Qi and Mijie Shi and Hui Fu and Xiuhui Zuo and Weixin Liu and Mingzhe Sun and Ming Xiong and Lidong Xia}, doi = {10.3847/1538-4357/ada444}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {180}, shortjournal = {The Astrophys. J.}, title = {Multiple episodes of remote brightenings driven by a coronal extreme-ultraviolet jet on the sun}, volume = {979}, year = {2025}, }
• (2025). Electron acceleration by multiple fast fermi reflections at earth’s bow shock. ApJ, 979(2), 179. (www)

  @article{ , abstract = {The generation of energetic particles in the Universe is an important topic in astrophysical and space physics. Although the diffusive shock acceleration has been acknowledged to play an essential role in particle acceleration, the injection problem has not been well resolved yet. Using measurements from the Magnetospheric Multiscale spacecraft, we report unexpected spiky enhancements of energetic electron flux in the upstream region of the Earth's bow shock. Such enhancements are then demonstrated to result from the accelerated electron population by shock reflection. Meanwhile, the magnetic field exhibits no variations except an increase in radius of curvature. Based on the results above, we uncover the underlying acceleration scenario. When the interplanetary magnetic field with a proper curvature approaches the bow shock, the two ends of a magnetic field line may touch the shock front earlier than its middle part. Magnetic mirror points form at the two field-line-shock intersections. The solar wind electrons are therefore trapped and bounce between two mirror points. Eventually, these electrons undergo fast Fermi reflection several times and gain substantial energies. The spacecraft observation of accelerated electrons is reproduced with a numerical method based on the reflection model. Such an acceleration process may be a potential solution to the injection problem.}, archive = {J_ApJ}, author = {Y. Y. Liu and J. B. Cao and C. M. Liu and Y. T. Song and D. K. Hu}, doi = {10.3847/1538-4357/ada5f0}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {179}, shortjournal = {The Astrophys. J.}, title = {Electron acceleration by multiple fast fermi reflections at earth’s bow shock}, volume = {979}, year = {2025}, }
• (2025). Constraints on primordial black holes from neff: Scalar-induced gravitational waves as an extra radiation component. ApJ, 979(2), 178. (www)

  @article{ , abstract = {In 2023 June, multiple pulsar timing array collaborations provided evidence for the existence of a stochastic gravitational-wave background. Scalar-induced gravitational waves (SIGWs), as one of the most likely sources of stochastic gravitational waves, have received widespread attention. When primordial curvature perturbations on small scales are sufficiently large, primordial black holes (PBHs) inevitably form, concurrently producing SIGWs with significant observable effects. These SIGWs can serve as an additional radiation component, influencing the relativistic degrees of freedom N eff . Taking into account primordial non-Gaussianity, we study the energy density spectrum of SIGWs up to the third order and use the current observational data of N eff to constrain small-scale primordial curvature perturbations and the abundance of PBHs.}, archive = {J_ApJ}, author = {Jing-Zhi Zhou and Yu-Ting Kuang and Zhe Chang and H. Lü}, doi = {10.3847/1538-4357/ada6b4}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {178}, shortjournal = {The Astrophys. J.}, title = {Constraints on primordial black holes from neff: Scalar-induced gravitational waves as an extra radiation component}, volume = {979}, year = {2025}, }
• (2025). What rogue hydrogen clouds tell us about galactic magnetic fields. ApJ, 979(2), 177. (www)

  @article{ , abstract = {Observations of the Milky Way and external galaxies support the idea that large-scale magnetic fields are concentrated in galactic disks, with halo magnetic fields at least an order of magnitude weaker. However, very little is known about the transition between the two. We present the discovery of linearly polarized radio emission at the interface between interacting shells of gas within a well-known grouping of high-velocity clouds (HVCs), the anticenter shell. Faraday rotation of diffuse emission and of background extragalactic compact sources demonstrates an enhancement of the field at the interface. This is the clearest observed example of an HVC altering the large-scale magnetic field at the disk–halo interface and is the first image of magnetic field effects in an HVC. These results demonstrate the possibility of future three-dimensional reconstruction of the Galactic magnetic field and showcase the versatility of the Synthesis Telescope at the Dominion Radio Astrophysical Observatory as one of the few existing telescopes that can exploit this new method of probing Galactic magnetism.}, archive = {J_ApJ}, author = {Bailey M. Forster and Tyler J. Foster and Roland Kothes and Alex S. Hill and Jo-Anne C. Brown}, doi = {10.3847/1538-4357/ad9338}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {177}, shortjournal = {The Astrophys. J.}, title = {What rogue hydrogen clouds tell us about galactic magnetic fields}, volume = {979}, year = {2025}, }
• (2025). A pride of satellites in the constellation leo? discovery of the leo VI milky way satellite ultra-faint dwarf galaxy with DELVE early data release 3. ApJ, 979(2), 176. (www)

  @article{ , abstract = {We report the discovery and spectroscopic confirmation of an ultra-faint Milky Way satellite in the constellation of Leo. This system was discovered as a spatial overdensity of resolved stars observed with Dark Energy Camera (DECam) data from an early version of the third data release of the DECam Local Volume Exploration (or DELVE) survey. The low luminosity ( {M}_{V}=-3.5{6}_{-0.37}^{+0.47} ; {L}_{V}=230{0}_{-700}^{+1200}{L}_{\odot } ), large size ( {R}_{1/2}=9{0}_{-30}^{+30} pc), and large heliocentric distance ( D=11{1}_{-6}^{+9} kpc) are all consistent with the population of ultra-faint dwarf galaxies (UFDs). Using Keck/DEIMOS observations of the system, we were able to spectroscopically confirm nine member stars, while measuring a tentative mass-to-light ratio of 70{0}_{-500}^{+1400}{M}_{\odot }/{L}_{\odot } and a nonzero metallicity dispersion of {\sigma }_{[\mathrm{Fe}/{\rm{H}}]}=0.1{9}_{-0.11}^{+0.14} , further confirming Leo VI's identity as a UFD. While the system has a highly elliptical shape, \epsilon =0.5{4}_{-0.29}^{+0.19} , we do not find any conclusive evidence that it is tidally disrupting. Moreover, despite the apparent on-sky proximity of Leo VI to members of the proposed Crater-Leo infall group, its smaller heliocentric distance and inconsistent position in energy–angular momentum space make it unlikely that Leo VI is part of the proposed infall group.}, archive = {J_ApJ}, author = {C. Y. Tan and W. Cerny and A. Drlica-Wagner and A. B. Pace and M. Geha and A. P. Ji and T. S. Li and M. Adamów and D. Anbajagane and C. R. Bom and J. A. Carballo-Bello and J. L. Carlin and C. Chang and A. Chaturvedi and A. Chiti and Y. Choi and M. L. M. Collins and A. Doliva-Dolinsky and P. S. Ferguson and R. A. Gruendl and D. J. James and G. Limberg and M. Navabi and D. Martínez-Delgado and C. E. Martínez-Vázquez and G. E. Medina and B. Mutlu-Pakdil and D. L. Nidever and N. E. D. Noël and A. H. Riley and J. D. Sakowska and D. J. Sand and J. Sharp and G. S. Stringfellow and C. Tolley and D. L. Tucker and A. K. Vivas and (DELVE Collaboration)}, doi = {10.3847/1538-4357/ad9b0c}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {176}, shortjournal = {The Astrophys. J.}, title = {A pride of satellites in the constellation leo? discovery of the leo VI milky way satellite ultra-faint dwarf galaxy with DELVE early data release 3}, volume = {979}, year = {2025}, }
• (2025). Fuzzy galaxies or cirrus? decomposition of galactic cirrus in deep wide-field images. ApJ, 979(2), 175. (www)

  @article{ , abstract = {Diffuse Galactic cirrus, or diffuse Galactic light (DGL), can be a prominent component in the background of deep wide-field imaging surveys. The DGL provides unique insights into the physical and radiative properties of dust grains in our Milky Way, and it also serves as a contaminant on deep images, obscuring the detection of background sources such as low surface brightness galaxies. However, it is challenging to disentangle the DGL from other components of the night sky. In this paper, we present a technique for the photometric characterization of Galactic cirrus based on (1) extraction of its filamentary or patchy morphology and (2) incorporation of color constraints obtained from Planck thermal dust models. Our decomposition method is illustrated using a ~10 deg 2 imaging data set obtained by the Dragonfly Telephoto Array, and its performance is explored using various metrics that characterize the flatness of the sky background. As a concrete application of the technique, we show how removal of cirrus allows low surface brightness galaxies to be identified on cirrus-rich images. We also show how modeling the cirrus in this way allows optical DGL intensities to be determined with high radiometric precision.}, archive = {J_ApJ}, author = {Qing Liu and Roberto Abraham and Peter G. Martin and William P. Bowman and Pieter van Dokkum and Shany Danieli and Ekta Patel and Steven R. Janssens and Zili Shen and Seery Chen and Ananthan Karunakaran and Michael A. Keim and Deborah Lokhorst and Imad Pasha and Douglas L. Welch}, doi = {10.3847/1538-4357/ad9b25}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {175}, shortjournal = {The Astrophys. J.}, title = {Fuzzy galaxies or cirrus? decomposition of galactic cirrus in deep wide-field images}, volume = {979}, year = {2025}, }
• (2025). Chemical abundances in the nuclear star cluster of the milky way: Alpha-element trends and their similarities with the inner bulge. ApJ, 979(2), 174. (www)

  @article{ , abstract = {Chemical characterization of the Galactic center is essential for understanding its formation and structural evolution. Trends of alpha ( α ) elements, such as magnesium, silicon, and calcium, serve as powerful diagnostic tools, offering insights into star formation rates and gas-infall history. However, high extinction has previously hindered such studies. In this study, we present a detailed chemical abundance analysis of M giants in the Milky Way's nuclear star cluster (NSC), focusing on α -element trends with metallicity. High-resolution, near-infrared spectra were obtained using the Immersion GRating INfrared Spectrograph on the Gemini South telescope for nine M giants. Careful selection of spectral lines, based on a solar-neighborhood control sample of 50 M giants, was implemented to minimize systematic uncertainties. Our findings show enhanced α -element abundances in the predominantly metal-rich NSC stars, consistent with trends in the inner bulge. The NSC stars follow the high-[ α /Fe] envelope seen in the solar vicinity's metal-rich population, indicating a high star formation rate. The α -element trends decrease with increasing metallicity, also at the highest metallicities. Our results suggest the NSC population likely shares a similar evolutionary history with the inner bulge, challenging the idea of a recent dominant star formation burst. This connection between the NSC and the inner-disk sequence suggests that the chemical properties of extragalactic NSCs of Milky Way–type galaxies could serve as a proxy for understanding the host galaxies' evolutionary processes.}, archive = {J_ApJ}, author = {Nils Ryde and Govind Nandakumar and Mathias Schultheis and Georges Kordopatis and Paola di Matteo and Misha Haywood and Rainer Schödel and Francisco Nogueras-Lara and R. Michael Rich and Brian Thorsbro and Gregory N. Mace and Oscar Agertz and Anish M. Amarsi and Jessica Kocher and Marta Molero and Livia Orglia and Giulia Pagnini and Emanuele Spitoni}, doi = {10.3847/1538-4357/ad9b2b}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {174}, shortjournal = {The Astrophys. J.}, title = {Chemical abundances in the nuclear star cluster of the milky way: Alpha-element trends and their similarities with the inner bulge}, volume = {979}, year = {2025}, }
• (2025). Deep Swift/UVOT observations of GOODS-N and the evolution of the ultraviolet luminosity function at 0.2 < z < 1.2. ApJ, 979(2), 173. (www)

  @article{ , abstract = {We present Swift Ultraviolet Optical Telescope (UVOT) observations of the deep field GOODS-N in four near-UV filters. A catalog of detected galaxies is reported, which will be used to explore galaxy evolution using UV emission. Swift/UVOT observations probe galaxies at z ≲ 1.5 and combine a wide field of view with moderate spatial resolution; these data complement the wide-field observations of Galaxy Evolution Explorer and the deep, high-angular-resolution observations by Hubble Space Telescope. Using our catalog of detected galaxies, we calculate the UV galaxy number counts as a function of apparent magnitude and compute the UV luminosity function (LF) and its evolution with redshift. From the LF fits in various redshift bins, we calculate the star formation rate density as a function of redshift and find evolution consistent with past works. We explore how different assumptions such as dust attenuation corrections can dramatically change how quickly the corrected star formation rate density changes with redshift. At these low redshifts, we find no trend between UV attenuation and redshift or absolute magnitude with significant scatter in the UV spectral slope β . This data set will complement the extensive observations of GOODS-N already in the literature.}, archive = {J_ApJ}, author = {Alexander Belles and Caryl Gronwall and Michael H. Siegel and Robin Ciardullo and Mat J. Page}, doi = {10.3847/1538-4357/ad9b2f}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {173}, shortjournal = {The Astrophys. J.}, title = {Deep Swift/UVOT observations of GOODS-N and the evolution of the ultraviolet luminosity function at 0.2 < z < 1.2}, volume = {979}, year = {2025}, }
• (2025). Elevated rates of tidal disruption events in active galactic nuclei. ApJ, 979(2), 172. (www)

  @article{ , abstract = {Advances in time domain astronomy have produced a growing population of flares from galactic nuclei, including both tidal disruption events (TDEs) and flares in active galactic nuclei (AGN). Because TDEs are uncommon and AGN variability is abundant, large-amplitude AGN flares are usually not categorized as TDEs. While TDEs are normally channelled by the collisional process of two-body scatterings over a relaxation timescale, the quadrupole moment of a gas disk alters the stellar orbits, allowing them to collisionlessly approach the central massive black hole (MBH). This leads to an effectively enlarged loss cone, the loss wedge. Earlier studies found a moderate enhancement, up to a factor ~2–3, of TDE rates {\dot{N}}_{{\rm{2b}}} for a static axisymmetric perturbation. Here, we study the loss wedge problem for an evolving AGN disk, which can capture large number of stars into the growing loss wedge over much shorter times. The rates {\dot{N}}_{{\rm{cl}}} of collisionless TDEs produced by these time-evolving disks are much higher than the collisional rates {\dot{N}}_{{\rm{2b}}} in a static loss wedge. We calculate the response of a stellar population to the axisymmetric potential of an adiabatically growing AGN disk and find that the highest rates of collisionless TDEs are achieved for the largest (i) MBH masses M • and (ii) disk masses M d . For M • ~ 10 7 M ⊙ and M d ~ 0.1 M • , the rate enhancement can be up to a factor {\dot{N}}_{{\rm{cl}}}/{\dot{N}}_{{\rm{2b}}}\unicode{x0007E}10 . The orbits of collisionless TDEs sometimes have a preferred orientation in apses, carrying implications for observational signatures of resulting flares.}, archive = {J_ApJ}, author = {Karamveer Kaur and Nicholas C. Stone}, doi = {10.3847/1538-4357/ad9b86}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {172}, shortjournal = {The Astrophys. J.}, title = {Elevated rates of tidal disruption events in active galactic nuclei}, volume = {979}, year = {2025}, }
• (2025). Segue 2 recently collided with the cetus-palca stream: New opportunities to constrain dark matter in an ultra-faint dwarf. ApJ, 979(2), 171. (www)

  @article{ , abstract = {Stellar streams in the Milky Way are promising detectors of low-mass dark matter (DM) subhalos predicted by ΛCDM. Passing subhalos induce perturbations in streams that indicate the presence of the subhalos. Understanding how known DM-dominated satellites impact streams is a crucial step toward using stream perturbations to constrain the properties of dark perturbers. Here, we cross-match a Gaia Early Data Release 3 and SEGUE member catalog of the Cetus-Palca stream (CPS) with H3 for additional radial velocity measurements and fit the orbit of the CPS using this six-dimensional (6D) data. We demonstrate for the first time that the ultra-faint dwarf Segue 2 had a recent (77 ± 5 Myr ago) close flyby (within the stream's 2 σ width) with the CPS. This interaction enables constraints on Segue 2's mass and density profile at larger radii ( { \mathcal O }(1) kpc) than are probed by its stars ( { \mathcal O }(10) pc). While Segue 2 is not expected to strongly affect the portion of the stream covered by our 6D data, we predict that if Segue 2's mass within ∼ 6 kpc is 5 × 10 9 M ⊙ , the CPS's velocity dispersion will be ∼ 40 km s −1 larger at ϕ 1 > 20° than at ϕ 1 < 0°. If no such heating is detected, Segue 2's mass cannot exceed 10 9 M ⊙ within ∼ 6 kpc. The proper motion distribution of the CPS near the impact site is mildly sensitive to the shape of Segue 2's density profile. This study presents a critical test for frameworks designed to constrain properties of dark subhalos from stream perturbations.}, archive = {J_ApJ}, author = {Hayden R. Foote and Gurtina Besla and Nicolás Garavito-Camargo and Ekta Patel and Guillaume F. Thomas and Ana Bonaca and Adrian M. Price-Whelan and Annika H. G. Peter and Dennis Zaritsky and Charlie Conroy}, doi = {10.3847/1538-4357/ad9b89}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {171}, shortjournal = {The Astrophys. J.}, title = {Segue 2 recently collided with the cetus-palca stream: New opportunities to constrain dark matter in an ultra-faint dwarf}, volume = {979}, year = {2025}, }
• (2025). Hydrogen column density variability in a sample of local compton-thin AGN II. ApJ, 979(2), 170. (www)

  @article{ , abstract = {We present the multiepoch analysis of 13 variable, nearby ( z ≲ 0.1), and Compton-thin (10 22 < N H < 1.5 × 10 24 cm −2 ) active galactic nuclei (AGN) selected from the 105-month BAT catalog. Analyzing all available archival soft and hard X-ray observations, we investigate the line-of-sight hydrogen column density ( N H,los ) variability on timescales ranging from a few days to approximately 20 yr. Each source is analyzed by simultaneously modeling the data with three physical torus models, providing tight constraints on torus properties, including the covering factor, the cloud dispersion, and the torus average hydrogen column density ( N H,av ). Our final sample includes 27 variable, Compton-thin AGN after implementing another 14 AGN analyzed in our previous work. We find that all sources require either flux or N H,los variability. Based on the degree of variability, we classify 37% of them as " N H,los Variable," 44% as "Nonvariable in N H,los, " and 19% as "Undetermined." Noticeably, there is no discernible difference between geometrical and intrinsic properties among the three variability classes, suggesting no intrinsic differences between the N H,los -variable and nonvariable sources within the considered sample. We measure the median variation in N H,los between any observation pair of the same source to be 25% with respect to the lowest N H,los measure in the pair. Furthermore, 48% of the analyzed sources require the inclusion of a Compton-thick reflector in the spectral fitting. Among these, 30% exhibit recorded 22 GHz water megamaser emission, suggesting a potential shared nature between the two structures.}, archive = {J_ApJ}, author = {A. Pizzetti and N. Torres-Albà and S. Marchesi and J. Buchner and I. Cox and X. Zhao and S. Neal and D. Sengupta and R. Silver and M. Ajello}, doi = {10.3847/1538-4357/ad9c64}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {170}, shortjournal = {The Astrophys. J.}, title = {Hydrogen column density variability in a sample of local compton-thin AGN II}, volume = {979}, year = {2025}, }
• (2025). The hidden magnetic structures of a solar intermediate filament revealed by the injected flare material. ApJ, 979(2), 169. (www)

  @article{ , abstract = {Solar filaments are spectacular objects in the solar atmosphere, consisting of accumulations of cool, dense, and partially ionized plasma suspended in the hot solar corona against gravity. The magnetic structures that support the filament material remain elusive, partly due to the lack of high-resolution magnetic field measurements in the chromosphere and corona. In this study, we reconstruct the magnetic structures of a solar intermediate filament using EUV observations and two different methods, to follow the injection of hot material from a B-class solar flare. Our analysis reveals the fine-scale magnetic structures of the filament, including a compact set of mutually wrapped magnetic fields encasing the cool filament material, two groups of helical magnetic structures intertwining with the main filament, and a series of arched magnetic loops positioned along the filament. Additionally, we find that the northern footpoints of the helical structures are rooted in the same location, while their southern footpoints are rooted in different areas. The results obtained in this study offer new insights into the formation and eruption mechanisms of solar filaments.}, archive = {J_ApJ}, author = {Xiaoli Yan and Zhike Xue and Jincheng Wang and Liheng Yang and Kaifan Ji and Defang Kong and Zhe Xu and Qiaoling Li and Liping Yang and Xinsheng Zhang}, doi = {10.3847/1538-4357/ad9d13}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {169}, shortjournal = {The Astrophys. J.}, title = {The hidden magnetic structures of a solar intermediate filament revealed by the injected flare material}, volume = {979}, year = {2025}, }
• (2025). ALMA/SCUBA-2 COSMOS survey: Properties of X-ray- and SED-selected active galactic nuclei in bright submillimeter galaxies. ApJ, 979(2), 168. (www)

  @article{ , abstract = {We investigate the properties of active galactic nuclei (AGNs) in the brightest submillimeter galaxies (SMGs) in the COSMOS field. We utilize the bright sample of the ALMA/SCUBA-2 COSMOS Survey (AS2COSMOS), which consists of 260 SMGs with S 870 μ m = 0.7–19.2 mJy at z = 0–6. We perform optical to millimeter spectral energy distribution (SED) modeling for the whole sample. We identify 24 AGN-host galaxies from the SEDs. Supplemented by 23 X-ray-detected AGNs (X-ray AGNs), we construct an overall sample of 40 AGN-host galaxies. The X-ray luminosity upper bounds indicate that the X-ray-undetected SED-identified AGNs are likely to be nearly Compton thick or have unusually suppressed X-ray emission. From visual classification, we identify 2{5}_{-5}^{+6} % of the SMGs without AGNs as major merger candidates. This fraction is almost consistent with the general galaxy population at z ∼ 2, suggesting that major mergers are not necessarily required for the enhanced star formation in SMGs. We also identify 4{7}_{-15}^{+16} % of the AGN hosts as major merger candidates, which is about twice as high as that in the SMGs without AGNs. This suggests that major mergers play a key role in triggering AGN activity in bright SMGs.}, archive = {J_ApJ}, author = {Ryosuke Uematsu and Yoshihiro Ueda and David M. Alexander and A. M. Swinbank and Ian Smail and Carolina Andonie and Chian-Chou Chen and Ugne Dudzevičiūtė and Soh Ikarashi and Kotaro Kohno and Yuichi Matsuda and Annagrazia Puglisi and Hideki Umehata and Wei-Hao Wang}, doi = {10.3847/1538-4357/ad9f3b}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {168}, shortjournal = {The Astrophys. J.}, title = {ALMA/SCUBA-2 COSMOS survey: Properties of X-ray- and SED-selected active galactic nuclei in bright submillimeter galaxies}, volume = {979}, year = {2025}, }
• (2025). A second candidate magnetic helium core white dwarf and 3 other variable white dwarfs in the globular cluster NGC 6397. ApJ, 979(2), 167. (www)

  @article{ , abstract = {Using archival Hubble Space Telescope observations, we report the discovery of four variable low-mass white dwarfs (WDs; 0.18 M ⊙ ≤ M ≤ 0.5 M ⊙ ) in the globular cluster NGC 6397. One source exhibits a periodic optical modulation of 5.21 ± 0.02 hr, which we interpret as potentially due to the rotation of a magnetic helium core WD (He WD). This makes this candidate the second magnetic He WD in NGC 6397, and one of the few He WDs with a measured rotation period. The other three candidates show aperiodic variability, with a change in magnitude ranging from ∼0.11 to 0.6. These discoveries highlight the importance of high-cadence photometric surveys in dense stellar environments. Follow-up spectroscopic observations are needed to confirm the nature of the variability of these systems.}, archive = {J_ApJ}, author = {Manuel Pichardo Marcano and Liliana E. Rivera Sandoval and Thomas J. Maccarone and Rene D. Rohrmann and Leandro G. Althaus and Craig O. Heinke and Diogo Belloni and Arash Bahramian}, doi = {10.3847/1538-4357/ada144}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {167}, shortjournal = {The Astrophys. J.}, title = {A second candidate magnetic helium core white dwarf and 3 other variable white dwarfs in the globular cluster NGC 6397}, volume = {979}, year = {2025}, }
• (2025). Bar instability and formation timescale across toomre’s q parameter and central mass concentration: Slow bar formation or true stability. ApJ, 979(2), 166. (www)

  @article{ , abstract = {We investigate the bar formation process using N -body simulations across the Toomre's parameter Q {}_{{\rm{\min }}} and central mass concentration (CMC), focusing principally on the formation timescale. Of importance is that, as suggested by cosmological simulations, disk galaxies have a limited time of ~8 Gyr in the Universe's timeline to evolve secularly, starting when they became physically and kinematically steady to prompt the bar instability. By incorporating this time limit, bar-unstable disks are further subdivided into those that establish a bar before and after that time, namely, the normal and the slowly bar-forming disks. Simulations demonstrate that evolutions of bar strengths and configurations of the slowly bar-forming and the bar-stable cases are nearly indistinguishable prior to 8 Gyr, albeit dynamically distinct, while differences can be noticed afterward. Differentiating them before 8 Gyr is possible by identifying the proto-bar, a signature of bar development visible in kinematical maps such as the Fourier spectrogram and the angular velocity field, which emerges in the former group 1–2 Gyr before the fully developed bar, whereas it is absent in the latter group until 8 Gyr and such bar-stable disk remains unbarred until at least 10 Gyr. In addition, we find complicated interplays between Q {}_{{\rm{\min }}} and CMC in regulating the bar formation. First, disk stabilization requires both high Q {}_{{\rm{\min }}} and CMC. Either high Q {}_{{\rm{\min }}} or high CMC only results in slow bar formation. Second, some hot disks can form a bar more rapidly than the colder ones in a specific range of Q {}_{{\rm{\min }}} and CMC.}, archive = {J_ApJ}, author = {T. Worrakitpoonpon}, doi = {10.3847/1538-4357/ada35f}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {166}, shortjournal = {The Astrophys. J.}, title = {Bar instability and formation timescale across toomre’s q parameter and central mass concentration: Slow bar formation or true stability}, volume = {979}, year = {2025}, }
• (2025). Dynamic evolution of magnetic flux ropes in active region 11429. II. magnetic characteristic of the footpoints during the preeruption and eruption phases. ApJ, 979(2), 165. (www)

  @article{ , abstract = {Magnetic flux rope (MFRs) are the most probable core structure of coronal mass ejections (CMEs). Their footpoints on the photosphere are the only feature for which their magnetic properties can be accurately measured, and to some extent, determine the property of the whole MFR. So far, the magnetic properties of footpoints are still a mystery. Y. Zhang et al. presented the dynamic evolution of four MFRs involved in a major eruption. For this special event, the footpoints of the MFRs could be identified by extreme-ultraviolet (EUV) brightening and MFR morphology during the preeruption phase, and by conjunction, EUV dimming during the eruption phase. This is a new effort to identify the footpoints of MFRs during the preeruption phase. This identification discloses that all footpoints originate out of the umbra and penumbra of the sunspots. The footpoint areas and magnetic flux during the preeruption phase are about 10 7 km 2 and around the order of 10 19 –10 20 Mx, respectively. During the eruption phase, the footpoint area and the magnetic flux are about 10 8 km 2 and around the order of 10 20 Mx, respectively. The temporal evolution of the magnetic features around the footpoints disclose that all footpoint pairs belong to nonconjugated opposite polarities. This observational evidence will help us to understand the magnetic nature of MFRs and their associated CMEs.}, archive = {J_ApJ}, author = {Yin Zhang and Jing Huang and Jihong Liu and Shangbin Yang and Yunfei Yang and Baolin Tan}, doi = {10.3847/1538-4357/ada383}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {165}, shortjournal = {The Astrophys. J.}, title = {Dynamic evolution of magnetic flux ropes in active region 11429. II. magnetic characteristic of the footpoints during the preeruption and eruption phases}, volume = {979}, year = {2025}, }
• (2025). Discovery and spectroscopic confirmation of aquarius III: A low-mass milky way satellite galaxy. ApJ, 979(2), 164. (www)

  @article{ , abstract = {We present the discovery of Aquarius III, an ultra-faint Milky Way satellite galaxy identified in the second data release of the DECam Local Volume Exploration survey. Based on deeper follow-up imaging with DECam, we find that Aquarius III is a low-luminosity ( {M}_{V}=-{2.5}_{-0.5}^{+0.3}; {L}_{V}={850}_{-260}^{+380}\ {L}_{\odot } ), extended ( {r}_{1/2}={41}_{-8}^{+9} pc) stellar system located in the outer halo ( D ⊙ = 85 ± 4 kpc). From medium-resolution Keck/DEIMOS spectroscopy, we identify 11 member stars and measure a mean heliocentric radial velocity of {v}_{\mathrm{sys}}=-{13.1}_{-0.9}^{+1.0}\ \mathrm{km}\ {{\rm{s}}}^{-1} for the system and place an upper limit of σ v < 3.5 km s −1 ( σ v < 1.6 km s −1 ) on its velocity dispersion at the 95% (68%) credible level. Based on calcium-triplet metallicities of the six brightest red giant members, we find that Aquarius III is very metal-poor ([Fe/H]= − 2.61 ± 0.21) with a statistically significant metallicity spread ( {\sigma }_{[\mathrm{Fe}/{\rm{H}}]}={0.46}_{-0.14}^{+0.26} dex). We interpret this metallicity spread as strong evidence that the system is a dwarf galaxy as opposed to a star cluster. Combining our velocity measurement with Gaia proper motions, we find that Aquarius III is currently situated near its orbital pericenter in the outer halo ( r peri = 78 ± 7 kpc) and that it is plausibly on first infall onto the Milky Way. This orbital history likely precludes significant tidal disruption from the Galactic disk, notably unlike other satellites with comparably low velocity dispersion limits in the literature. Thus, if further velocity measurements confirm that its velocity dispersion is truly below σ v ≲ 2 km s −1 , Aquarius III may serve as a useful laboratory for probing galaxy formation physics in low-mass halos.}, archive = {J_ApJ}, author = {W. Cerny and A. Chiti and M. Geha and B. Mutlu-Pakdil and A. Drlica-Wagner and C. Y. Tan and M. Adamów and A. B. Pace and J. D. Simon and D. J. Sand and A. P. Ji and T. S. Li and A. K. Vivas and E. F. Bell and J. L. Carlin and J. A. Carballo-Bello and A. Chaturvedi and Y. Choi and A. Doliva-Dolinsky and O. Y. Gnedin and G. Limberg and C. E. Martínez-Vázquez and S. Mau and G. E. Medina and M. Navabi and N. E. D. Noël and V. M. Placco and A. H. Riley and I. U. Roederer and G. S. Stringfellow and C. R. Bom and P. S. Ferguson and D. J. James and D. Martínez-Delgado and P. Massana and D. L. Nidever and J. D. Sakowska and L. Santana-Silva and N. F. Sherman and E. J. Tollerud and (DELVE Collaboration)}, doi = {10.3847/1538-4357/ad8eba}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {164}, shortjournal = {The Astrophys. J.}, title = {Discovery and spectroscopic confirmation of aquarius III: A low-mass milky way satellite galaxy}, volume = {979}, year = {2025}, }
• (2025). Residual energy and broken symmetry in reduced magnetohydrodynamics. ApJ, 979(2), 163. (www)

  @article{ , abstract = {Alfvénic interactions that transfer energy from large to small spatial scales lie at the heart of magnetohydrodynamic turbulence. An important feature of the turbulence is the generation of negative residual energy—excess energy in magnetic fluctuations compared to velocity fluctuations. By contrast, an MHD Alfvén wave has equal amounts of energy in fluctuations of each type. Alfvénic quasi-modes that do not satisfy the Alfvén wave dispersion relation and exist only in the presence of a nonlinear term can contain either positive or negative residual energy, but until now, an intuitive physical explanation for why negative residual energy is preferred has remained elusive. This paper shows that the equations of reduced MHD are symmetric in that they have no intrinsic preference for one sign of the residual energy over the other. An initial state that is not an exact solution to the equations can break this symmetry in a way that leads to net-negative residual energy generation. Such a state leads to a solution with three distinct parts: nonresonant Alfvénic quasi-modes, normal modes produced to satisfy initial conditions, and resonant normal modes that grow in time. The latter two parts strongly depend on initial conditions; the resulting symmetry breaking leads to net-negative residual energy both in Alfvénic quasi-modes and ω = k ∥ V A = 0 modes. These modes have net-positive residual energy in the equivalent boundary value problem, suggesting that the initial value setup is a better match for solar wind turbulence.}, archive = {J_ApJ}, author = {S. Dorfman and M. Abler and S. Boldyrev and C. H. K. Chen and S. Greess}, doi = {10.3847/1538-4357/ad9012}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {163}, shortjournal = {The Astrophys. J.}, title = {Residual energy and broken symmetry in reduced magnetohydrodynamics}, volume = {979}, year = {2025}, }
• (2025). A study of the star clusters’ population in the giant molecular cloud g174+2.5. ApJ, 979(2), 162. (www)

  @article{ , abstract = {We study the structure, interstellar absorption, color–magnitude diagrams (CMDs), kinematics, and dynamical state of embedded star clusters in the star-forming region associated with the giant molecular cloud G174+2.5. Our investigation is based on photometric data from the UKIDSS Galactic Plane Survey catalog and astrometric data from the Gaia DR3 catalogs. First, we recover all the known embedded clusters and candidate clusters in the region using surface density maps. Then, for the detected clusters, we determine their general parameters: the center positions, radii, number of stars, and reddening. To evaluate the reddening, we use both the NICEST algorithm and the Q -method. Both methods produce consistent extinction maps in the regions of the four studied clusters. However, the Q -method yields a much smaller color scatter in the CMD. For four clusters in particular (S235 North-West, S235 A-B-C, S235 Central, and S235 East1+East2), we were able to compute individual membership probabilities, the cluster distances, the cluster masses, and their average proper motions. By building on these results, we have studied the clusters' kinematics and dynamics. Moreover, we estimate the mass of the gas component and the star formation efficiency in the regions of these four clusters. Finally, we provide an estimate of the total energy of the stellar and gas components in the area of these four clusters to determine whether the clusters are bound (here, we consider a "cluster" as the system "stars + gas"). The gravitational bound strongly depends on the region for which we estimate the gas mass. If we consider the mass of the entire cloud, all these four clusters turn out to be bound.}, archive = {J_ApJ}, author = {Tatyana A. Permyakova and Giovanni Carraro and Anton F. Seleznev and Andrej M. Sobolev and Dmitry A. Ladeyschikov and Maria S. Kirsanova}, doi = {10.3847/1538-4357/ad957d}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {162}, shortjournal = {The Astrophys. J.}, title = {A study of the star clusters’ population in the giant molecular cloud g174+2.5}, volume = {979}, year = {2025}, }
• (2025). Maximum energy of particles in plasmas. ApJ, 979(2), 161. (www)

  @article{ , abstract = {Particles are accelerated to very high, nonthermal energies in space, solar, and astrophysical plasma environments. In cosmic-ray physics, the Hillas limit is often used as a rough estimate (or the necessary condition) of the maximum energy of particles. This limit is based on the concepts of one-shot direct acceleration by a system-wide motional electric field, as well as stochastic and diffusive acceleration in strongly turbulent environments. However, it remains unclear how well this limit explains the actual observed maximum energies of particles. Here, we show, based on a systematic review, that the observed maximum energy of particles—those in space, solar, astrophysical, and laboratory environments—often reach the energy predicted by the Hillas limit. We also found several exceptions, such as electrons in solar flares and jet-terminal lobes of radio galaxies, as well as protons in planetary radiation belts, where deviations from this limit occur. We discuss possible causes of such deviations, and we argue in particular that there is a good chance of detecting ultra-high-energy (∼100 GeV) solar flare electrons that have not yet been detected. We anticipate that this study will facilitate further interdisciplinary discussions on the maximum energy of particles and the underlying mechanisms of particle acceleration in diverse plasma environments.}, archive = {J_ApJ}, author = {Mitsuo Oka and Kazuo Makishima and Toshio Terasawa}, doi = {10.3847/1538-4357/ad9916}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {161}, shortjournal = {The Astrophys. J.}, title = {Maximum energy of particles in plasmas}, volume = {979}, year = {2025}, }
• (2025). Morphology of 137 fast radio bursts down to microsecond timescales from the first CHIME/FRB baseband catalog. ApJ, 979(2), 160. (www)

  @article{ , abstract = {We present a spectro-temporal analysis of 137 fast radio bursts (FRBs) from the first CHIME/FRB baseband catalog, including 125 one-off bursts and 12 repeat bursts, down to microsecond resolution using the least-squares optimization fitting routine fitburst . We measure subburst components within burst envelopes as narrow as ~23 μ s (FWHM), with 20% of the sample displaying substructures narrower than 100 μ s, offering constraints on emission mechanisms. Scattering timescales in the sample range from 30 μ s to 13 ms at 600 MHz. Our measured values are compared with those in the first CHIME/FRB intensity catalog, revealing that nearly one-third of our sample exhibits additional burst components at higher time resolutions. We observe no correlations between scattering time and dispersion measure, rotation measure, or linear polarization fraction, with the latter suggesting that depolarization due to multipath propagation is negligible in our sample. Bursts with narrower envelopes (≤1 ms) in our sample exhibit higher flux densities, indicating the potential presence of submillisecond FRBs that are being missed by our real-time system below a brightness threshold. Most multicomponent bursts in our sample exhibit subburst separations of ≤1 ms, with no bursts showing separations < 41 μ s, even at a time resolution of 2.56 μ s, but both scattering and low signal-to-noise ratio can hinder the detection of additional components. Lastly, given the morphological diversity of our sample, we suggest that one-off and repeating FRBs can come from different classes but have overlapping property distributions.}, archive = {J_ApJ}, author = {Ketan R. Sand and Alice P. Curtin and Daniele Michilli and Victoria M. Kaspi and Emmanuel Fonseca and Kenzie Nimmo and Ziggy Pleunis and Kaitlyn Shin and Mohit Bhardwaj and Charanjot Brar and Matt Dobbs and Gwendolyn M. Eadie and B.M. Gaensler and Ronniy C. Joseph and Calvin Leung and Robert Main and Kiyoshi W. Masui and Ryan Mckinven and Ayush Pandhi and Aaron B. Pearlman and Masoud Rafiei-Ravandi and Mawson W. Sammons and Kendrick Smith and Ingrid H. Stairs}, doi = {10.3847/1538-4357/ad9b11}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {160}, shortjournal = {The Astrophys. J.}, title = {Morphology of 137 fast radio bursts down to microsecond timescales from the first CHIME/FRB baseband catalog}, volume = {979}, year = {2025}, }
• (2025). The puzzling long GRB 191019A: Evidence for kilonova light. ApJ, 979(2), 159. (www)

  @article{ , abstract = {GRB 191019A was a long gamma-ray burst (GRB) lasting ~65 s and, as such, originally thought to be linked to a core-collapse supernova. However, even though follow-up observations identified the optical counterpart close to the bright nucleus of a nearby ancient galaxy ( z = 0.248), no associated supernova was found. This led to the suggestion that the burst was caused by the merger of two compact stellar objects, likely in a dense circumnuclear environment. By using a recently developed diagnostic tool based on prompt emission temporal properties, we noticed that GRB 191019A falls among those long GRBs which are associated with compact mergers and with evidence of kilonova light. We thus reanalyzed unpublished GROND multicolor ( g^{\prime} r^{\prime} i^{\prime} z^{\prime} JH{K}_{s} ) data obtained between 0.4 and 15 days posttrigger. Image subtraction confirmed the optical counterpart in all four optical bands, with GROND tracking its fading until 1.5 days postburst. Incorporating publicly available Swift-XRT data, a joint fit of an afterglow plus a kilonova model revealed a better match than an afterglow-only scenario. The resulting kilonova properties resemble those of AT2017gfo associated with the binary neutron star merger GW170817, with a total ejected mass of ~0.06 M ⊙ . Contrary to previous findings inferring a high-density circumburst environment ( n 0 ~ 10 7−8 cm −3 ), our analysis finds standard conditions ( n 0 ~ 1 cm −3 ), suggesting the long duration of GRB 191019A was intrinsic rather than due to jet interaction with a dense external medium.}, archive = {J_ApJ}, author = {G. Stratta and A. M. Nicuesa Guelbenzu and S. Klose and A. Rossi and P. Singh and E. Palazzi and C. Guidorzi and A. Camisasca and S. Bernuzzi and A. Rau and M. Bulla and F. Ragosta and E. Maiorano and D. Paris}, doi = {10.3847/1538-4357/ad9b7b}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {159}, shortjournal = {The Astrophys. J.}, title = {The puzzling long GRB 191019A: Evidence for kilonova light}, volume = {979}, year = {2025}, }
• (2025). Potential interior structures and habitability of super-earth exoplanets LHS 1140 b, k2-18 b, TOI-1452 b, and TOI-1468 c. ApJ, 979(2), 158. (www)

  @article{ , abstract = {We analyze four super-Earth exoplanets, LHS 1140 b, K2-18 b, TOI-1452 b, and TOI-1468 c, which orbit M dwarf stars in the habitable zone. Their relative proximity, within 40 pc, makes them prime candidates for follow-up observations and atmospheric and habitability studies. This paper aims to assess their internal structure and habitability, considering their tidal heating, atmospheric heating, and global transport. We model the interior structure of the planets by applying Bayesian inference to an exoplanet's interior model. A model with constant quality factor is used to calculate the range of tidal heating, and a one-dimensional analytical model of tidally locked planets is used to assess their surface temperature distribution and habitability. Assuming no or only thin atmospheres, K2-18 b and TOI-1468 c are likely to be water worlds. However, TOI-1452 b and LHS 1140 b may have rocky surfaces. We find that tidal heating is not enough to raise the global mean surface temperature, but greenhouse heating can effectively do so. If the considered planets have retained thick atmospheres, K2-18 b, TOI-1468 c, and TOI-1452 b may, for significant atmospheric heating and heat transport factors, be too hot to sustain liquid water on their surfaces. However, the lower instellation of LHS 1140 b and the nonzero probability of it having a rocky surface give more space for habitable conditions on the planet.}, archive = {J_ApJ}, author = {Mangesh Daspute and Amri Wandel and Ravi Kumar Kopparapu and Volker Perdelwitz and Jerusalem Tamirat Teklu and Lev Tal-Or}, doi = {10.3847/1538-4357/ad9ba9}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {158}, shortjournal = {The Astrophys. J.}, title = {Potential interior structures and habitability of super-earth exoplanets LHS 1140 b, k2-18 b, TOI-1452 b, and TOI-1468 c}, volume = {979}, year = {2025}, }
• (2025). The 100 pc white dwarf sample in the SDSS footprint. II. a new look at the spectral evolution of white dwarfs. ApJ, 979(2), 157. (www)

  @article{ , abstract = {We increase the spectroscopic completeness of the 100 pc white dwarf sample in the Sloan Digital Sky Survey footprint with 840 additional spectra. Our spectroscopy is 86% complete for white dwarfs hotter than T eff = 5000 K, where H α remains visible and provides reliable constraints on the atmospheric composition. We identify 2108 DA white dwarfs with pure hydrogen atmospheres, and show that ultramassive DA white dwarfs with M ≥ 1.1 M ⊙ are an order of magnitude less common below 10,000 K. This is consistent with a fraction of them getting stuck on the crystallization sequence due to 22 Ne distillation. In addition, there are no ultramassive DA white dwarfs with M ≥ 1.1 M ⊙ and T eff ≤ 6000 K in our sample, likely because Debye cooling makes them rapidly fade away. We detect a significant trend in the fraction of He atmosphere white dwarfs as a function of temperature; the fraction increases from 9% at 20,000 K to 32% at 6000 K. This provides direct evidence of convective mixing in cool DA white dwarfs. Finally, we detect a relatively tight sequence of low-mass DQ white dwarfs in color–magnitude diagrams for the first time. We discuss the implications of this tight DQ sequence, and conclude with a discussion of the future prospects from the upcoming Ultraviolet Transient Astronomy Satellite mission and the large-scale multi-fiber spectroscopic surveys.}, archive = {J_ApJ}, author = {Mukremin Kilic and Pierre Bergeron and Simon Blouin and Adam Moss and Warren R. Brown and Antoine Bédard and Gracyn Jewett and Marcel A. Agüeros}, doi = {10.3847/1538-4357/ad9bb3}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {157}, shortjournal = {The Astrophys. J.}, title = {The 100 pc white dwarf sample in the SDSS footprint. II. a new look at the spectral evolution of white dwarfs}, volume = {979}, year = {2025}, }
• (2025). Linear bending wave propagation in laminar and turbulent disks. ApJ, 979(2), 156. (www)

  @article{ , abstract = {Bending waves are perhaps the most fundamental and analytically tractable phenomena in warped disk dynamics. In this work, we conduct 3D grid-based, numerical experiments of bending waves in laminar, viscous hydrodynamic and turbulent, weakly magnetized disks, capturing their behavior in unprecedented detail. We clearly elucidate the theory from first principles, wherein the general Fourier–Hermite formalism can be simplified to a reduced framework which extends previous results toward locally isothermal disks. We obtain remarkable agreement with our laminar simulations wherein the tilt evolution is well described by the reduced theory, while higher-order vertical modes should be retained for capturing the detailed disk twisting and internal velocity profiles. We then relax this laminar assumption and instead launch bending waves atop a magnetorotationally turbulent disk. Although the turbulence can be quantified with an effective α parameter, the bending waves behave distinctly from a classical viscous evolution and are readily disrupted when the turbulent velocity is comparable to the induced warping flows. This may have implications for the inclination damping rates induced by planet–disk interactions, the capture rate of black holes in active galactic nucleus disks or the warped shapes assumed by disks in misaligned systems.}, archive = {J_ApJ}, author = {Callum W. Fairbairn}, doi = {10.3847/1538-4357/ad9c73}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {156}, shortjournal = {The Astrophys. J.}, title = {Linear bending wave propagation in laminar and turbulent disks}, volume = {979}, year = {2025}, }
• (2025). A parameter study of the electromagnetic signatures of an analytical mini-disk model for supermassive black hole binary systems. ApJ, 979(2), 155. (www)

  @article{ , abstract = {Supermassive black holes (SMBHs) are thought to be located at the centers of most galactic nuclei. When galaxies merge, they form SMBH binary (SMBHB) systems, and these central SMBHs will also merge at later times, producing gravitational waves. Because galaxy mergers are likely gas-rich environments, SMBHBs are also potential sources of electromagnetic (EM) radiation. The EM signatures depend on gas dynamics, orbital dynamics, and radiation processes. The gas dynamics are governed by general-relativistic magnetohydrodynamics (MHD) in a time-dependent spacetime. Numerically solving the MHD equations for a time-dependent binary spacetime is computationally expensive. Therefore, it is challenging to conduct a full exploration of the parameter space of these systems and the resulting EM signatures. We have developed an analytical accretion-disk model for the mini-disks of an SMBHB system and produced images and light curves using a general-relativistic ray-tracing code and a superimposed harmonic binary BH metric. This analytical model greatly reduces the time and computational resources needed to explore these systems, while incorporating some key information from simulations. We present a parameter-space exploration of the SMBHB system, in which we study the dependence of the EM signatures on the spins of the BHs, the mass ratio, the accretion rate, the viewing angle, and the initial binary separation. Additionally, we study how the commonly used fast-light approximation affects the EM signatures and evaluate its validity in general-relativistic MHD simulations.}, archive = {J_ApJ}, author = {Kaitlyn Porter and Scott C. Noble and Eduardo M. Gutiérrez and Joaquín Pelle and Manuela Campanelli and Jeremy Schnittman and Bernard J. Kelly}, doi = {10.3847/1538-4357/ad9c74}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {155}, shortjournal = {The Astrophys. J.}, title = {A parameter study of the electromagnetic signatures of an analytical mini-disk model for supermassive black hole binary systems}, volume = {979}, year = {2025}, }
• (2025). Numerical simulation of electron magnetohydrodynamics with landau-quantized electrons in magnetar crusts. ApJ, 979(2), 154. (www)

  @article{ , abstract = {In magnetar crusts, magnetic fields are sufficiently strong to confine electrons into a small to moderate number of quantized Landau levels. This can have a dramatic effect on the crust's thermodynamic properties, generating field-dependent de Haas–van Alphen oscillations. We previously argued that the large-amplitude oscillations of the magnetic susceptibility could enhance the ohmic dissipation of the magnetic field by continuously generating small-scale, rapidly dissipating field features. This could be important to magnetar field evolution and contribute to their observed higher temperatures. To study this, we performed quasi-3D numerical simulations of electron MHD in a representative volume of neutron star crust matter, for the first time including the magnetization and magnetic susceptibility resulting from Landau quantization. We find that the potential enhancement in the ohmic dissipation rate due to this effect can be a factor  ∼3 for temperatures of the order of 10 8 K, and  ∼4.5 for temperatures of the order of 5 × 10 7 K, depending on the magnetic field configuration. The nonlinear Hall term is crucial to this amplification: without it, the magnetic field decay is only enhanced by a factor  ≲2 even at 5 × 10 7 K. These effects generate a high wavenumber plateau in the magnetic energy spectrum associated with the small-scale de Haas–van Alphen oscillations. Our results suggest that this mechanism could help explain the magnetar heating problem, though due to the effect's temperature-dependence, full magneto-thermal evolution simulations in a realistic stellar model are needed to judge whether it is viable explanation.}, archive = {J_ApJ}, author = {Peter B. Rau and Ira Wasserman}, doi = {10.3847/1538-4357/ad9dea}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {154}, shortjournal = {The Astrophys. J.}, title = {Numerical simulation of electron magnetohydrodynamics with landau-quantized electrons in magnetar crusts}, volume = {979}, year = {2025}, }
• (2025). SIRI-2 detection of the gamma-ray burst 221009A. ApJ, 979(2), 153. (www)

  @article{ , abstract = {SIRI-2 is a collection of strontium iodide gamma-ray detectors sensitive at approximately 400 keV to 10 MeV, launched on the Department of Defense's STPSat-6 to geosynchronous orbit. SIRI-2 detected the gamma-ray burst (GRB) 221009A and, unlike most GRB detectors, was not saturated and did not require any pulse pileup corrections. The energetics of this burst as measured by SIRI-2 are consistent with those found by other instruments, and the Band function fits to the spectra are consistent with those from the unsaturated Insight and GECAM instruments and similar to corrected spectra from the Fermi Gamma-ray Burst Monitor, but softer than those found by Konus-Wind when that instrument was saturated. The total fluence measured with SIRI-2 was measured to be 0.140 ± 0.002 erg cm −2 , lower than other instruments, likely due to the increasing background of SIRI-2 forcing the calculation to use a smaller time interval. An extrapolation of the distributions of fluences from GRBs to the fluence of 221009A measured with SIRI-2 indicates bursts brighter than this one should occur about once every 4000 yr.}, archive = {J_ApJ}, author = {Lee J. Mitchell and Justin D. Finke and Bernard Phlips and W. Neil Johnson and Emily Kong}, doi = {10.3847/1538-4357/ad9ea3}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {153}, shortjournal = {The Astrophys. J.}, title = {SIRI-2 detection of the gamma-ray burst 221009A}, volume = {979}, year = {2025}, }
• (2025). Evolution of magnetohydrodynamic turbulence in the expanding solar wind: Residual energy and intermittency. ApJ, 979(2), 152. (www)

  @article{ , abstract = {We conduct 3D magnetohydrodynamic simulations of decaying turbulence in the context of the solar wind. To account for the spherical expansion of the solar wind, we implement the expanding box model. The initial turbulence comprises uncorrelated counterpropagating Alfvén waves and exhibits an isotropic power spectrum. Our findings reveal the consistent generation of negative residual energy whenever nonlinear interactions are present, independent of the normalized cross helicity σ c and compressibility. The spherical expansion facilitates this process. The resulting residual energy is primarily distributed in the perpendicular direction, with S 2 ( b ) − S 2 ( u ) ∝ l ⊥ or equivalently -{E}_{r}\propto {k}_{\perp }^{-2} . Here S 2 ( b ) and S 2 ( u ) are second-order structure functions of magnetic field and velocity respectively. In most runs, S 2 ( b ) develops a scaling relation {S}_{2}({\boldsymbol{b}})\propto {l}_{\perp }^{1/2} ( {E}_{b}\propto {k}_{\perp }^{-3/2} ). In contrast, S 2 ( u ) is consistently shallower than S 2 ( b ), which aligns with in situ observations of the solar wind. We observe that the higher-order statistics of the turbulence, which act as a proxy for intermittency, depend on the initial σ c and are strongly affected by the expansion effect. Generally, the intermittency is more pronounced when the expansion effect is present. Finally, we find that in our simulations, although the negative residual energy and intermittency grow simultaneously as the turbulence evolves, the causal relation between them seems to be weak, possibly because they are generated on different scales.}, archive = {J_ApJ}, author = {Chen Shi and Nikos Sioulas and Zesen Huang and Marco Velli and Anna Tenerani and Victor Réville}, doi = {10.3847/1538-4357/ad9f38}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {152}, shortjournal = {The Astrophys. J.}, title = {Evolution of magnetohydrodynamic turbulence in the expanding solar wind: Residual energy and intermittency}, volume = {979}, year = {2025}, }
• (2025). Phase-transition-induced collapse of proto-compact stars and its implication for supernova explosions. ApJ, 979(2), 151. (www)

  @article{ , abstract = {A hadron–quark phase transition (PT) may trigger supernova explosions during stellar core collapse. However, both success and failure have occurred in previous attempts to explode dying stars via this mechanism. We systematically explore the outcomes of the PT-induced collapse of mock proto-compact stars (PCSs) with a constant entropy and lepton fraction, with spherically symmetric general relativistic hydrodynamic simulations and a controlled series of hybrid equations of state. Our results reveal the qualitative dependence of successful and failed explosions on the PT and quark matter characteristics. A small portion (∼0.04%−1%) of the released binding energy Δ E B transforms into the diagnostic explosion energy E exp,diag , which saturates at  ∼6 × 10 51 erg near the black hole formation. Note that our E exp,diag represents an upper limit of the final explosion energies in realistic supernova simulations. We draw the phase diagrams indicative of the possible fates of supernova explosions driven by hadron−quark PTs, where the control parameters are the onset density, the energy gap of the PT, and the quark matter speed of sound. Our findings can guide further self-consistent investigations on PT-driven core-collapse supernovae and help identify hadron−quark PT-induced PCS collapse from future observations.}, archive = {J_ApJ}, author = {Xu-Run Huang and Shuai Zha and Ming-chung Chu and Evan P. O’Connor and Lie-Wen Chen}, doi = {10.3847/1538-4357/ada146}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {151}, shortjournal = {The Astrophys. J.}, title = {Phase-transition-induced collapse of proto-compact stars and its implication for supernova explosions}, volume = {979}, year = {2025}, }
• (2025). Cosmic reionization on computers: The evolution of the ionizing background and mean free path. ApJ, 979(2), 150. (www)

  @article{ , abstract = {Observations of the end stages of reionization indicate that at z ≈ 5–6, the ionizing background is not uniform and the mean free path (MFP) changes drastically. As the MFP is closely related to the distribution of Lyman-limit systems (LLSs) and damped Ly α absorbers, it is important to understand them. In this study, we utilize the Cosmic Reionization on Computers (CROC) simulations, which have both sufficient spatial resolution to resolve galaxy formation and LLSs alongside a fully coupled radiative transfer, to simulate the reionization processes. We analyze two CROC boxes with distinct reionization histories and find that the distributions of the ionizing background in both simulations display significant skewness. Further, the ionizing background in the late-reionization box still displays significant fluctuations (∼40%) at z ≈ 5. We also measure the MFP along sightlines that center on potential quasar hosting halos. The evolution of the MFP measured from these sightlines exhibits a break that coincides with the disappearance of all the neutral islands in the reionization history of each box. In the absence of LLSs, the MFP will be biased high by ≈20% at z ≈ 5. We also compare the MFPs measured in random sightlines. We find that at z ≈ 5, the MFPs measured in sightlines that start from massive halos are systematically smaller by ≈10% compared with the MFPs measured in random sightlines. We attribute this difference to the concentration of dense structures within 1 pMpc of massive halos. Our findings highlight the importance of high-fidelity models in the interpretation of observational measurements.}, archive = {J_ApJ}, author = {Jiawen Fan and Huanqing Chen and Camille Avestruz and Affan Khadir}, doi = {10.3847/1538-4357/ada1d3}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {150}, shortjournal = {The Astrophys. J.}, title = {Cosmic reionization on computers: The evolution of the ionizing background and mean free path}, volume = {979}, year = {2025}, }
• (2025). Collision-induced absorption spectra of n2 and CH4. ApJ, 979(2), 149. (www)

  @article{ , abstract = {Collision-induced spectra are essential for radiative transfer modeling of Titan's atmosphere. We present experimental spectra of nitrogen–methane mixtures with an accompanying fit of N 2 -CH 4 collision-induced absorption in the 30–400 cm −1 region at about 130 K. We found a peak absorption of 2.30 × 10 −5 cm −1 amagat −2 at 75 cm −1 and a secondary peak of 1.35 × 10 −5 cm −1 amagat −2 at 206.5 cm −1 , which agrees with previous studies. Our work does not support the suggestion that N 2 -CH 4 CIA in the far-infrared should be increased by about 50%, as suggested by spectroscopic modeling of Titan using data from A. Borysow & C. Tang.}, archive = {J_ApJ}, author = {Ryan M. Johnson and Peter F. Bernath and Brant Billinghurst and Jianbao Zhao}, doi = {10.3847/1538-4357/ada24a}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {149}, shortjournal = {The Astrophys. J.}, title = {Collision-induced absorption spectra of n2 and CH4}, volume = {979}, year = {2025}, }
• (2025). Physics-driven explosions of stripped high-mass stars: Synthetic light curves and spectra of stripped-envelope supernovae with broad light curves. ApJ, 979(2), 148. (www)

  @article{ , abstract = {Stripped-envelope supernovae (SESNe) represent a significant fraction of core-collapse supernovae, arising from massive stars that have shed their hydrogen and, in some cases, helium envelopes. The origins and explosion mechanisms of SESNe remain a topic of active investigation. In this work, we employ radiative-transfer simulations to model the light curves and spectra of a set of explosions of single, solar-metallicity, massive Wolf–Rayet stars with ejecta masses ranging from 4 to 11 M ⊙ , which were computed from a turbulence-aided and neutrino-driven explosion mechanism. We analyze these synthetic observables to explore the impact of varying ejecta mass and helium content on observable features. We find that the light curve shape of these progenitors with high ejecta masses is consistent with observed SESNe with broad light curves but not the peak luminosities. The commonly used analytic formula based on rising bolometric light curves overestimates the ejecta mass of these high-initial-mass progenitor explosions by a factor of up to 2.6. In contrast, the calibrated method by Haynie et al., which relies on late-time decay tails, reduces uncertainties to an average of 20% within the calibrated ejecta mass range. Spectroscopically, the He i 1.083 μ m line remains prominent even in models with as little as 0.02 M ⊙ of helium. However, the strength of the optical He i lines is not directly proportional to the helium mass but instead depends on a complex interplay of factors such as the 56 Ni distribution, composition, and radiation field. Thus, producing realistic helium features requires detailed radiative transfer simulations for each new hydrodynamic model.}, archive = {J_ApJ}, author = {Jing Lu and Brandon L. Barker and Jared Goldberg and Wolfgang E. Kerzendorf and Maryam Modjaz and Sean M. Couch and Joshua V. Shields and Andrew G. Fullard}, doi = {10.3847/1538-4357/ada26d}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {148}, shortjournal = {The Astrophys. J.}, title = {Physics-driven explosions of stripped high-mass stars: Synthetic light curves and spectra of stripped-envelope supernovae with broad light curves}, volume = {979}, year = {2025}, }
• (2025). Optical quasiperiodic oscillations with 550 day periodicity in the reverberation-mapped broad line quasar PG 1411+442. ApJ, 979(2), 147. (www)

  @article{ , abstract = {In this paper, optical quasiperiodic oscillations (QPOs) with 550 day periodicity related to a candidate subparsec binary black hole (BBH) system are reported in the reverberation-mapped broad line quasar PG 1411+442 but with a different line profile of broad H α from that of broad H β in its rms spectrum. First, considering the sine function to describe the 18.8 yr long light curves from the Catalina Sky Survey, All-Sky Automated Survey for Supernovae, and Zwicky Transient Facility, 550 day periodicity can be confirmed with a confidence level higher than 5 σ . Second, the stable 550 day optical QPOs can be reconfirmed with confidence levels higher than 5 σ by the generalized Lomb–Scargle periodogram, the sine-like phase-folded light curves, and the weighted wavelet z -transform technique determined power maps. Third, based on simulated light curves by the continuous autoregressive process, a confidence level higher than 3.5 σ can be confirmed for the optical QPOs not related to intrinsic active galactic nucleus (AGN) variability. Moreover, considering the spatial separation of central two black hole (BH) accreting systems with smaller than expected sizes of broad emission line regions, a central total BH mass higher than 10 6 M ⊙ could lead to few effects of supposed BBH systems on estimated virial BH masses. Meanwhile, disk precession is not preferred due to the similar estimated sizes of the optical and near-ultraviolet emission regions, and jet precession can be ruled out due to PG 1411+442 being a radio-quiet quasar. The results strongly indicate it would be practicable, by applying very different line profiles of broad Balmer emission lines, to detect candidate BBH systems in normal broad line AGN in the near future.}, archive = {J_ApJ}, author = {Xue-Guang Zhang}, doi = {10.3847/1538-4357/ada284}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {147}, shortjournal = {The Astrophys. J.}, title = {Optical quasiperiodic oscillations with 550 day periodicity in the reverberation-mapped broad line quasar PG 1411+442}, volume = {979}, year = {2025}, }
• (2025). Modeling the magnetic connection from earth to solar corona during the may 11 geomagnetic superstorm. ApJ, 979(2), 146. (www)

  @article{ , abstract = {In early 2024 May, the solar active region AR 13664 released a series of X-class solar flares and multiple coronal mass ejections (CMEs) that resulted in the strongest geomagnetic storm of the last 20 yr. This study aims at improving our understanding of the magnetic connectivity between Earth and the solar corona by reconstructing the magnetic footpoint of the Earth on the solar surface during this geomagnetic superstorm. A Monte Carlo simulation was applied to model the random walk of interplanetary magnetic field lines due to low-frequency turbulence in the solar wind. This model uses local diffusion coefficients dependent on magnetic fluctuations and the correlation length of solar wind turbulence. The simulation revealed an enhanced diffusion of magnetic field lines due to the passage of CMEs, leading to a broader area of solar surface magnetically connected to Earth, particularly near AR 13664. This proximity facilitated the rapid propagation of solar energetic protons, increasing fluxes observed at L1. The findings have significant implications for predicting space weather effects on Earth and other solar system bodies, contributing to the development of more accurate models for future space exploration missions. Since the Parker spiral reconstruction is consistent with the Magnetic Connectivity Tool, validating the model's reliability, it shows promise for reconstructing magnetic connections for potential real-time purposes.}, archive = {J_ApJ}, author = {Alessandro Ippolito and Tommaso Alberti and Fabio Giannattasio}, doi = {10.3847/1538-4357/ada35a}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {146}, shortjournal = {The Astrophys. J.}, title = {Modeling the magnetic connection from earth to solar corona during the may 11 geomagnetic superstorm}, volume = {979}, year = {2025}, }
• (2025). Redshifting the study of cold brown dwarfs and exoplanets: The mid-infrared wavelength region as an indicator of surface gravity and mass. ApJ, 979(2), 145. (www)

  @article{ , abstract = {JWST is opening many avenues for exploration. For cold brown dwarfs and exoplanets, JWST has opened the door to the mid-infrared wavelength region, where such objects emit significant energy. For the first time, astronomers have access to mid-infrared spectroscopy for objects colder than 600 K. The first spectra appear to validate the model suite known as ATMO 2020++: atmospheres that include disequilibrium chemistry and have a nonadiabatic pressure–temperature relationship. Preliminary fits to JWST spectroscopy of Y dwarfs show that the slope of the energy distribution from λ ≈ 4.5 μ m to λ ≈ 10 μ m is very sensitive to gravity. We explore this phenomenon using PH 3 -free ATMO 2020++ models and updated Wide-field Infrared Survey Explorer W2−W3 colors. We find that an absolute 4.5 μ m flux measurement constrains temperature, and the ratio of the 4.5 μ m flux to the 10–15 μ m flux is sensitive to gravity and less sensitive to metallicity. We identify 10 T dwarfs with red W2−W3 colors that are likely to be very-low-gravity, young, few-Jupiter-mass objects; one of these is the previously known COCONUTS-2b. The unusual Y dwarf WISEPA J182831.08+265037.8 is blue in W2−W3, and we find that the 4–18 μ m JWST spectrum is well reproduced if the system is a pair of high-gravity 400 K dwarfs. Recently published JWST colors and luminosity-based effective temperatures for late-T and -Y dwarfs further corroborate the ATMO 2020++ models, demonstrating the potential for significant improvement in our understanding of cold, very-low-mass bodies in the solar neighborhood.}, archive = {J_ApJ}, author = {S. K. Leggett and Pascal Tremblin}, doi = {10.3847/1538-4357/ad8fa6}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {145}, shortjournal = {The Astrophys. J.}, title = {Redshifting the study of cold brown dwarfs and exoplanets: The mid-infrared wavelength region as an indicator of surface gravity and mass}, volume = {979}, year = {2025}, }
• (2025). Giant hall waves launched by superconducting phase transition in pulsars. ApJ, 979(2), 144. (www)

  @article{ , abstract = {The cores of pulsars are expected to become superconducting soon after birth. The transition to type-II superconductivity is associated with the bunching of magnetic field lines into discrete superconducting flux tubes which possess enormous tension. The coupling of the crust to the flux tubes implies the existence of huge tangential magnetic fields at the crust–core interface. We show that the transition to superconductivity triggers a highly nonlinear response in the Hall drift of the crustal magnetic field, an effect which was neglected in previous numerical modeling. We argue that at the time of the phase transition giant Hall waves are launched from the crust–core interface toward the surface. Our models show that if the crust contains a multipolar magnetic field ∼10 13 G, the amplitude of the Hall waves is ∼10 15 G. The elastic deformation of the lattice is included in our models, which allows us to track the time-dependent shear stresses everywhere in the crust. The simulations indicate that the Hall waves may be strong enough to break the crust, and could cause star quakes which trigger rotation glitches and changes in the radio pulse profile. The Hall waves also couple to slow magnetospheric changes, which cause anomalous braking indices. The emission of the giant Hall waves from the crust–core interface facilitates fast flux expulsion from the superconducting core, provided that the flux tubes in the core are themselves sufficiently mobile. For all of the flux tube mobility prescriptions implemented in this work, the core approaches the Meissner state with B = 0 at late times.}, archive = {J_ApJ}, author = {Ashley Bransgrove and Yuri Levin and Andrei M. Beloborodov}, doi = {10.3847/1538-4357/ad90a3}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {144}, shortjournal = {The Astrophys. J.}, title = {Giant hall waves launched by superconducting phase transition in pulsars}, volume = {979}, year = {2025}, }
• (2025). Unveiling low-frequency eclipses in spider millisecond pulsars using wideband GMRT observations. ApJ, 979(2), 143. (www)

  @article{ , abstract = {Eclipses of radio emission have been reported for ∼58 spider millisecond pulsars (MSPs), of which only around 19% have been extensively studied. Such studies at low frequencies are crucial for probing the properties of the eclipse medium. This study investigates eclipses in 10 MSPs in compact orbit using wide-bandwidth observations with the Giant Metrewave Radio Telescope. We report the first evidence of eclipsing for PSR J2234+0944 and J2214+3000 in one epoch, while no evidence of eclipsing was observed in the subsequent two epochs, indicating temporal evolution of the eclipse cutoff frequency in these systems. Constraints on the eclipse cutoff frequency were obtained for PSR J1555–2908, J1810+1744, and J2051–0827. Moreover, for the first time, we detected an eclipse at a nonstandard orbital phase (∼0.5) for PSR J1810+1744, with a duration longer than the eclipse observed at superior conjunction. No eclipses were detected for PSR J0751+1807, J1738+0333, and J1807–2459A at 300–500 MHz and 550–750 MHz. We calculated the mass-loss rate of the companion for PSR J1555–2908 and PSR J1810+1744 and found that these rates are insufficient to ablate the companion stars. We cataloged the \dot{E}/{a}^{2} , mass function, Roche lobe filling factor, and inclination angle for compact MSP binaries with low-mass companions and found that higher spin-down flux does not guarantee eclipses. Our analysis, supported by the Kolmogorov–Smirnov statistic, confirms that eclipsing black widow binaries generally exhibit a higher mass function compared to noneclipsing black widow binaries, consistent with previous studies.}, archive = {J_ApJ}, author = {Sangita Kumari and Bhaswati Bhattacharyya and Devojyoti Kansabanik and Rahul Sharan and Ankita Ghosh and Jayanta Roy}, doi = {10.3847/1538-4357/ad93ba}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {143}, shortjournal = {The Astrophys. J.}, title = {Unveiling low-frequency eclipses in spider millisecond pulsars using wideband GMRT observations}, volume = {979}, year = {2025}, }
• (2025). Peculiar dust emission within the orion molecular cloud. ApJ, 979(2), 142. (www)

  @article{ , abstract = {It is widely assumed that dust opacities in molecular clouds follow a power-law profile with an index, β . Recent studies of the Orion Molecular Cloud (OMC) 2/3 complex, however, show a flattening in the spectral energy distribution (SED) at λ > 2 mm, implying nonconstant indices on scales ≳0.08 pc. The origin of this flattening is not yet known, but it may be due to the intrinsic properties of the dust grains or contamination from other sources of emission. We investigate the SED slopes in OMC 2/3 further using observations of six protostellar cores with Northern Extended Millimeter Array (NOEMA) from 2.9–3.6 mm and Atacama Large Millimeter/submillimeter Array (ALMA) Atacama Compact Array in Band 4 (1.9–2.1 mm) and Band 5 (1.6–1.8 mm) on core and envelope scales of ∼0.02–0.08 pc. We confirm flattened opacity indices between 2.9 mm and 3.6 mm for the six cores with β ≈ −0.16 to 1.45, which are notably lower than the β -values of >1.3 measured for these sources on 0.08 pc scales from single-dish data. Four sources have consistent SED slopes between the ALMA data and the NOEMA data. We propose that these sources may have a significant fraction of emission coming from large dust grains in embedded disks, which biases the emission more at longer wavelengths. Two sources, however, had inconsistent slopes between the ALMA and NOEMA data, indicating different origins of emission. These results highlight how care is needed when combining multiscale observations or extrapolating single-band observations to other wavelengths.}, archive = {J_ApJ}, author = {Parisa Nozari and Sarah Sadavoy and Edwige Chapillon and Brian Mason and Rachel Friesen and Ian Lowe and Thomas Stanke and James Di Francesco and Thomas Henning and Qizhou Zhang and Amelia Stutz}, doi = {10.3847/1538-4357/ad93c7}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {142}, shortjournal = {The Astrophys. J.}, title = {Peculiar dust emission within the orion molecular cloud}, volume = {979}, year = {2025}, }
• (2025). Detecting stellar flares in photometric data using hidden markov models. ApJ, 979(2), 141. (www)

  @article{ , abstract = {We present a hidden Markov model (HMM) for discovering stellar flares in light-curve data of stars. HMMs provide a framework to model time series data that are nonstationary; they allow for systems to be in different states at different times and consider the probabilities that describe the switching dynamics between states. In the context of the discovery of stellar flares, we exploit the HMM framework by allowing the light curve of a star to be in one of three states at any given time step: quiet , firing , or decaying . This three-state HMM formulation is designed to enable straightforward identification of stellar flares, their duration, and associated uncertainty. This is crucial for estimating the flare's energy, and is useful for studies of stellar flare energy distributions. We combine our HMM with a celerite model that accounts for quasiperiodic stellar oscillations. Through an injection recovery experiment, we demonstrate and evaluate the ability of our method to detect and characterize flares in stellar time series. We also show that the proposed HMM flags fainter and lower energy flares more easily than traditional sigma-clipping methods. Lastly, we visually demonstrate that simultaneously conducting detrending and flare detection can mitigate biased estimations arising in multistage modeling approaches. Thus, this method paves a new way to calculate stellar flare energy. We conclude with an example application to one star observed by TESS, showing how the HMM compares with sigma clipping when using real data.}, archive = {J_ApJ}, author = {J. Arturo Esquivel and Yunyi Shen and Vianey Leos-Barajas and Gwendolyn Eadie and Joshua S. Speagle and Radu V Craiu and Amber Medina and James R. A. Davenport}, doi = {10.3847/1538-4357/ad95f6}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {141}, shortjournal = {The Astrophys. J.}, title = {Detecting stellar flares in photometric data using hidden markov models}, volume = {979}, year = {2025}, }
• (2025). The PANORAMIC survey: Pure parallel wide area legacy imaging with JWST/NIRCam. ApJ, 979(2), 140. (www)

  @article{ , abstract = {We present the PANORAMIC survey, a pure parallel extragalactic imaging program with JWST/NIRCam observed during Cycle 1. The survey obtained ∼530 square arcmin of NIRCam imaging from 1–5 μ m, totaling ∼192 hr of science integration time. This represents the largest on-sky time investment of any Cycle 1 GO extragalactic NIRCam imaging program by nearly a factor of 2. The survey includes ∼432 square arcmin of novel sky area not yet observed with JWST using at least six NIRCam broadband filters, increasing the existing area covered by similar Cycle 1 data by ∼60%. Additionally, 70 square arcmin was also covered by a seventh filter (F410M). A fraction of PANORAMIC data (∼200 square arcmin) was obtained in or around extragalactic deep fields, enhancing their legacy value. Pure parallel observing naturally creates a "wedding cake" survey with both wide and ultra-deep tiers, with 5 σ point-source depths at F444W ranging from 27.8–29.4 (ABmag), and with minimized cosmic variance. The ≳6-filter strategy yields remarkably good photometric redshift performance, achieving similar median scatter and outlier fraction as CANDELS ( σ NMAD ∼ 0.07; η ∼ 0.2), enabling a wealth of science across redshift without need for follow-up or ancillary data. We overview the proposed survey, the data obtained as part of this program, and document the science-ready data products in the data release. PANORAMIC has delivered wide-area and deep imaging with excellent photometric performance, demonstrating that pure parallel observations with JWST are a highly efficient observing mode that is key to acquiring a complete picture of galaxy evolution from rare bright galaxies to fainter, more abundant sources across redshifts.}, archive = {J_ApJ}, author = {Christina C. Williams and Pascal A. Oesch and Andrea Weibel and Gabriel Brammer and Aidan P. Cloonan and Katherine E. Whitaker and Laia Barrufet and Rachel Bezanson and Rebecca A. A. Bowler and Pratika Dayal and Marijn Franx and Jenny E. Greene and Anne Hutter and Zhiyuan Ji and Ivo Labbé and Sinclaire M. Manning and Michael V. Maseda and Mengyuan Xiao}, doi = {10.3847/1538-4357/ad97bc}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {140}, shortjournal = {The Astrophys. J.}, title = {The PANORAMIC survey: Pure parallel wide area legacy imaging with JWST/NIRCam}, volume = {979}, year = {2025}, }
• (2025). What can DKIST/DL-NIRSP tell us about quiet-sun magnetism?. ApJ, 979(2), 139. (www)

  @article{ , abstract = {Quiet-Sun regions cover most of the Sun's surface; their magnetic fields contribute significantly to solar chromospheric and coronal heating. However, characterizing the magnetic fields of the quiet Sun is challenging due to their weak polarization signal. The 4 m Daniel K. Inouye Solar Telescope (DKIST) is expected to improve our understanding of quiet-Sun magnetism. In this paper, we assess the diagnostic capability of the Diffraction Limited Near Infrared Spectropolarimeter (DL-NIRSP) instrument on DKIST for the energy transport processes in the quiet-Sun photosphere. To this end, we synthesize high-resolution, high-cadence Stokes profiles of the Fe i 630 nm lines using a realistic magnetohydrodynamic simulation, degrade them to emulate the DKIST/DL-NIRSP observations, and subsequently infer the vector magnetic and velocity fields. For the assessment, we first verify that a widely used flow tracking algorithm, the Differential Affine Velocity Estimator for Vector Magnetograms, works well for estimating the large-scale (>200 km) photospheric velocity fields with these high-resolution data. We then examine how the accuracy of the inferred velocity depends on the temporal resolution. Finally, we investigate the reliability of the Poynting flux estimate and its dependence on the model assumptions. The results suggest that the unsigned Poynting flux, estimated with existing schemes, can account for about 71.4% and 52.6% of the reference ground truth at \mathrm{log}\tau =0.0 and \mathrm{log}\tau =-1 . However, the net Poynting flux tends to be significantly underestimated. The error mainly arises from the underestimated contribution of the horizontal motion. We discuss the implications for DKIST observations.}, archive = {J_ApJ}, author = {Jiayi Liu and Xudong Sun and Peter W. Schuck and Sarah A. Jaeggli}, doi = {10.3847/1538-4357/ad98e7}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {139}, shortjournal = {The Astrophys. J.}, title = {What can DKIST/DL-NIRSP tell us about quiet-sun magnetism?}, volume = {979}, year = {2025}, }
• (2025). An investigation into the selection and colors of little red dots and active galactic nuclei. ApJ, 979(2), 138. (www)

  @article{ , abstract = {Recently, a large number of compact sources at z > 4 with blue UV slopes and extremely red rest-frame optical slopes have been found in James Webb Space Telescope (JWST) extragalactic surveys. As a subsample of these sources, commonly called "little red dots" (LRDs), have been spectroscopically observed to host a broad-line active galactic nucleus (AGN), they have been the focus of multiple recent studies in an attempt to understand the origin of their UV and optical emission. Here, we assemble a sample of 123 LRDs from the literature along with spectroscopic and photometric JWST-identified samples of AGNs to compare their colors and spectral slopes. We find that while obscured AGNs at z < 6 have highly dissimilar colors to LRDs, unobscured AGNs at z < 6 span a wide range of colors, with only a subsample showing colors similar to LRDs. At z > 6, the majority of the unobscured AGNs that have been found in these samples are LRDs, but this may be related to the fact that these sources are at large bolometric luminosities. Because LRDs occupy a unique position in galaxy color space, they are more straightforward to target, and the large number of broad-line AGNs that do not have LRD colors and slopes are therefore underrepresented in many spectroscopic surveys because they are more difficult to preselect. Current LRD selection techniques return a large and disparate population, including many sources having 2–5 μ m colors impacted by emission-line flux boosting in individual filters.}, archive = {J_ApJ}, author = {Kevin N. Hainline and Roberto Maiolino and Ignas Juodžbalis and Jan Scholtz and Hannah Übler and Francesco D’Eugenio and Jakob M. Helton and Yang Sun and Fengwu Sun and Brant Robertson and Sandro Tacchella and Andrew J. Bunker and Stefano Carniani and Stephane Charlot and Emma Curtis-Lake and Eiichi Egami and Benjamin D. Johnson and Xiaojing Lin and Jianwei Lyu and Pablo G. Pérez-González and Pierluigi Rinaldi and Maddie S. Silcock and Giacomo Venturi and Christina C. Williams and Christopher N. A. Willmer and Chris Willott and Junyu Zhang and Yongda Zhu}, doi = {10.3847/1538-4357/ad9920}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {138}, shortjournal = {The Astrophys. J.}, title = {An investigation into the selection and colors of little red dots and active galactic nuclei}, volume = {979}, year = {2025}, }
• (2025). Potential technosignature from anomalously low Deuterium/Hydrogen in planetary water depleted by nuclear fusion technology. ApJ, 979(2), 137. (www)

  @article{ , abstract = {Deuterium–deuterium (DD) fusion is viewed as an ideal energy source for humanity in the far future, given a vast seawater supply of D. Here, we consider long-lived, extraterrestrial, technological societies that develop DD fusion. If such a society persisted over geologic timescales, oceanic deuterium would diminish. For an ocean mass and initial deuterium/hydrogen (D/H) ratio that were Earth-like, fusion power use of only ∼10 times that projected for humankind next century would deplete the D/H ratio in ∼(a few) × 10 8 yr to values below that of the local interstellar medium (ISM). Ocean masses of a few percent of Earth's would reach an anomalously low D/H in ∼10 6 –10 7 yr. The timescale shortens with greater energy consumption, smaller oceans, or lower initial D/H. Here, we suggest that anomalous D/H in planetary water below local ISM values of ∼16 × 10 −6 (set by Big Bang nucleosynthesis plus deuterium loss onto dust or small admixtures of deuterium-poor stellar material) may be a technosignature. Unlike SETI using radio signals, anomalous D/H would persist for eons, even if civilizations perished or relocated. We discuss the wavelengths of strong absorption features for detecting D/H anomalies in atmospheric water vapor. These are vibrational O–D stretching at 3.7 μ m in transmission spectroscopy of Earth-like worlds, ∼1.5 μ m (in the wings of the 1.4 μ m water band) in the shorter near-infrared for direct imaging by the Habitable Worlds Observatory, and ∼7.5-8 μ m (in the wings of the broad 6.3 μ m bending vibration of water) for concepts like the Large Interferometer for Exoplanets.}, archive = {J_ApJ}, author = {David C. Catling and Joshua Krissansen-Totton and Tyler D. Robinson}, doi = {10.3847/1538-4357/ad99a9}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {137}, shortjournal = {The Astrophys. J.}, title = {Potential technosignature from anomalously low Deuterium/Hydrogen in planetary water depleted by nuclear fusion technology}, volume = {979}, year = {2025}, }
• (2025). What does the LMC look like? it depends on [M/H] and age. ApJ, 979(2), 136. (www)

  @article{ , abstract = {We offer a new way to look at the LMC through stellar mono-abundance and mono-age mono-abundance maps. These maps are based on ≳500,000 member stars with estimates of [M/H] ( σ [M/H] ~ 0.17) and age ({\sigma }_{{\rm{log}}\tau }\unicode{x0007E}0.15 ), derived from Gaia Data Release 3 XP spectra and photometry, which are tied to and validated against APOGEE. This results in the first area-complete, metallicity- and age-differentiated stellar maps of any disk galaxy. Azimuthally averaged, these maps reveal a surprisingly simple picture of the Milky Way's largest satellite galaxy. For any [M/H] below −0.1 dex, the LMC's radial profile is well described by a simple exponential, but with a scale length that steadily shrinks toward higher metallicities, from nearly 2.3 kpc at [M/H] = −1.8 to only 0.75 kpc at [M/H] = −0.25, as fit by forward modeling the spatial distribution of mono-[M/H] populations. The prominence of the bar decreases dramatically with [M/H], making it barely discernible at [M/H] ≲ −1.5. Yet, even for metal-rich populations, the bar has little impact on the azimuthally averaged profile of the mono-abundance components. Including ages, we find that the scale length is a greater function of age than of metallicity, with younger populations far more centrally concentrated. Only at old ages does the scale length change, specifically decrease, with increasing metallicity. These findings provide quantitative support for a scenario in which the LMC built its stellar structure effectively outside-in.}, archive = {J_ApJ}, author = {Neige Frankel and Rene Andrae and Hans-Walter Rix and Joshua Povick and Vedant Chandra}, doi = {10.3847/1538-4357/ad9b17}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {136}, shortjournal = {The Astrophys. J.}, title = {What does the LMC look like? it depends on [M/H] and age}, volume = {979}, year = {2025}, }
• (2025). Testing the breakdown of the asteroseismic scaling relations in luminous red giants. ApJ, 979(2), 135. (www)

  @article{ , abstract = {Nearly all cool, evolved stars are solar-like oscillators, and fundamental stellar properties can be inferred from these oscillations with asteroseismology. Scaling relations are commonly used to relate global asteroseismic properties—the frequency of maximum power {\nu }_{{\rm{\max }}} and the large-frequency separation Δ ν —to stellar properties. Mass, radius, and age can then be inferred with the addition of stellar spectroscopy. There is excellent agreement between seismic radii and fundamental data on the lower red giant branch and red clump. However, the scaling relations appear to breakdown in luminous red-giant stars. We attempt to constrain the contributions of the asteroseismic parameters to the observed breakdown. We test the {\nu }_{{\rm{\max }}} and Δ ν scaling relations separately, by using stars of known mass and radius in star clusters and the Milky Way's high- α sequence. We find evidence that the Δ ν scaling relation contributes to the observed breakdown in luminous giants more than the {\nu }_{{\rm{\max }}} relation. We test different methods of mapping the observed Δ ν to the mean density via a correction factor, F Δ ν , and find a  ≈ 1%–3% difference in the radii in the luminous giant regime, depending on the technique used to measure F Δ ν . The differences between the radii inferred by these two techniques are too small on the luminous giant branch to account for the inflated seismic radii observed in evolved giant stars. Finally, we find that the F Δ ν correction is insensitive to the adopted mixing length, chosen by calibrating the models to observations of T eff .}, archive = {J_ApJ}, author = {Amanda L. Ash and Marc H. Pinsonneault and Mathieu Vrard and Joel C. Zinn}, doi = {10.3847/1538-4357/ad9b18}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {135}, shortjournal = {The Astrophys. J.}, title = {Testing the breakdown of the asteroseismic scaling relations in luminous red giants}, volume = {979}, year = {2025}, }
• (2025). Can active galactic nuclei activity be enhanced by ram pressure Stripping?—X-ray perspective. ApJ, 979(2), 134. (www)

  @article{ , abstract = {Ram pressure stripping (RPS) is an important process that plays a significant role in shaping the evolution of cluster galaxies and their surrounding environment. Despite its recognized significance, the potential connection between RPS and active galactic nuclei (AGN) activity in cluster galaxies remains poorly understood. Recent claims, based on optical emission-line diagnostics, have suggested such a connection. Here, we investigate this relationship from an X-ray perspective, using a sample of galaxies undergoing RPS in four nearby galaxy clusters: A1656, A1367, A426, and A3627. This study is the first to test such a connection from an X-ray standpoint. Our analysis reveals no signs of enhanced X-ray AGN activity in our sample, with most RPS galaxies (~90%) showing X-ray luminosities below 10 41 erg s −1 in their central point sources. Moreover, there is no noticeable difference in X-ray AGN activity among RPS galaxies compared to a control sample of non-RPS galaxies, as demonstrated by the similar X-ray luminosities observed in their central point sources. While the most luminous X-ray AGN in our sample is found in ESO 137-002, a galaxy undergoing RPS in A3627, there is no evidence for a widespread enhancement of X-ray AGN activity due to RPS. Given the limited sample size of our study, this could also indicate that either the X-ray AGN enhancement from RPS is at most weak or the timescale for the X-ray AGN enhancement is short. This emphasizes the need for further investigations with larger X-ray samples to better understand the impact of RPS on AGN activity in cluster galaxies.}, archive = {J_ApJ}, author = {Juhi Tiwari and Ming Sun and Rongxin Luo and Matteo Fossati and Chen Chien-Ting J. and Prathamesh Tamhane}, doi = {10.3847/1538-4357/ad9b7f}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {134}, shortjournal = {The Astrophys. J.}, title = {Can active galactic nuclei activity be enhanced by ram pressure Stripping?—X-ray perspective}, volume = {979}, year = {2025}, }
• (2025). Tides on lava worlds: Application to close-in exoplanets and the early Earth–Moon system. ApJ, 979(2), 133. (www)

  @article{ , abstract = {Understanding the physics of planetary magma oceans has been the subject of growing efforts, in light of the increasing abundance of solar system samples and extrasolar surveys. A rocky planet harboring such an ocean is likely to interact tidally with its host star, planetary companions, or satellites. To date, however, models of the tidal response and heat generation of magma oceans have been restricted to the framework of weakly viscous solids, ignoring the dynamical fluid behavior of the ocean beyond a critical melt fraction. Here we provide a handy analytical model that accommodates this phase transition, allowing for a physical estimation of the tidal response of lava worlds. We apply the model in two settings: the tidal history of the early Earth–Moon system in the aftermath of the giant impact, and the tidal interplay between short-period exoplanets and their host stars. For the former, we show that the fluid behavior of the Earth's molten surface drives efficient early lunar recession to ~25 Earth radii within 10 4 –10 5 yr, in contrast with earlier predictions. For close-in exoplanets, we report on how their molten surfaces significantly change their spin–orbit dynamics, allowing them to evade spin–orbit resonances and accelerating their track toward tidal synchronization from a gigayear to megayear timescale. Moreover, we reevaluate the energy budgets of detected close-in exoplanets, highlighting how the surface thermodynamics of these planets are likely controlled by enhanced, fluid-driven tidal heating, rather than vigorous insolation, and how this regime change substantially alters predictions for their surface temperatures.}, archive = {J_ApJ}, author = {Mohammad Farhat and Pierre Auclair-Desrotour and Gwenaël Boué and Tim Lichtenberg and Jacques Laskar}, doi = {10.3847/1538-4357/ad9b93}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {133}, shortjournal = {The Astrophys. J.}, title = {Tides on lava worlds: Application to close-in exoplanets and the early Earth–Moon system}, volume = {979}, year = {2025}, }
• (2025). Finding lensed radio sources with the very large array sky survey. ApJ, 979(2), 132. (www)

  @article{ , abstract = {Radio observations of strongly lensed objects are valuable as cosmological probes. Lensed radio sources have proven difficult to identify, in large part due to the limited depth and angular resolution of the previous generation of radio sky surveys, and, as such, only a few dozen lensed radio sources are known. In this work, we present the results of a pilot study, using the Very Large Array Sky Survey (VLASS) in combination with optical data to more efficiently identify lensed radio sources. We obtain high-resolution (0 \mathop{.}\limits^{\unicode{x02033}} 2) VLA follow-up observations for 11 targets that we identify using three different techniques: (i) a search for compact radio sources offset from galaxies with high lensing potential, (ii) VLASS detections of known lensed galaxies, and (iii) VLASS detections of known lensed quasars. Five of our targets show radio emission from the lensed images, including 100% of the lensed optical quasar systems. This work demonstrates the efficacy of combining deep- and high-resolution wide-area radio and optical survey data to efficiently find lensed radio sources, and we discuss the potential impact of such an approach using next-generation surveys with the Vera C. Rubin Observatory, Euclid, and Nancy Grace Roman Space Telescope.}, archive = {J_ApJ}, author = {Michael N. Martinez and Yjan A. Gordon and Keith Bechtol and Gillian Cartwright and Peter S. Ferguson and Miranda Gorsuch}, doi = {10.3847/1538-4357/ad9c37}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {132}, shortjournal = {The Astrophys. J.}, title = {Finding lensed radio sources with the very large array sky survey}, volume = {979}, year = {2025}, }
• (2025). Reverberation mapping of two variable active galactic nuclei: Probing the distinct characteristics of the inner and outer broad-line regions. ApJ, 979(2), 131. (www)

  @article{ , abstract = {Current reverberation mapping (RM) studies primarily focus on single emission lines, particularly the H β line, which may not fully reveal the geometry and kinematic properties of the broad-line region (BLR). To overcome this limitation, we have conducted multiline RM observations on two highly variable active galactic nuclei (AGNs), KUG 1141+371 and UGC 3374, using the Lijiang 2.4 m telescope. Our goal was to investigate the detailed structures of different regions within the BLR. We measured the time lags of multiple broad emission lines (H α , H β , H γ , He i , and He ii ) and found clear evidence of radial ionization stratification in the BLRs of both AGNs. Velocity-resolved RM analysis revealed distinct geometry and kinematics between the inner and outer regions of the BLRs. Assuming that the velocity-resolved lags reflect the kinematics of the BLR, our observations indicate that: (1) in KUG 1141+371, the inner BLR exhibits outflow signatures, while the outer region is consistent with virialized motion; and (2) in UGC 3374, the inner region displays virial motion, while the outer region shows inflow. Furthermore, we detected "breathing" behavior in the outer BLR regions of both AGNs, while the inner BLR regions show "anti-breathing," which may be linked to intrinsic BLR properties. We discuss these findings in the context of various BLR formation models, highlighting the importance of long-term, multiline RM campaigns in understanding of BLR structure and evolution. Additionally, our results suggest that the observed stratification in BLR geometry and kinematics may contribute to the scatter in black hole mass estimates and the rapid changes in velocity-resolved RM signatures reported in recent studies.}, archive = {J_ApJ}, author = {Hai-Cheng Feng and Sha-Sha Li and J. M. Bai and H. T. Liu and Kai-Xing Lu and Yu-Xuan Pang and Mouyuan Sun and Jian-Guo Wang and Yerong Xu and Yang-Wei Zhang and Shuying Zhou}, doi = {10.3847/1538-4357/ad9c71}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {131}, shortjournal = {The Astrophys. J.}, title = {Reverberation mapping of two variable active galactic nuclei: Probing the distinct characteristics of the inner and outer broad-line regions}, volume = {979}, year = {2025}, }
• (2025). Chandra follow-up observations of swift-BAT-selected AGNs III. ApJ, 979(2), 130. (www)

  @article{ , abstract = {The cosmic X-ray background (CXB) is dominated by the obscured and unobscured coronal light of active galactic nuclei (AGN). At energies below 10 keV, the CXB can be well explained by models taking into account the known AGN and the observed distribution of their obscuring, line-of-sight column densities, N H,l.o.s . However, at energies around the Compton reflection hump (~30 keV), the models fall short of the data. This suggests the existence of a population of as yet undetected Compton-thick (CT) AGN ( N H,l.o.s > 1.5 × 10 24 cm −2 ) whose X-ray spectra are dominated by the light that has been reprocessed by the obscuring material. In this work, we continue the effort to find and catalog all local ( z < 0.05) CT AGN. To this end, we obtained soft X-ray data with Chandra for six local BAT detected sources lacking ROSAT (0.1–2.4 keV) counterparts, indicating potential obscuration. We fit their spectra with Bayesian and least squares methods using two different models, borus02 and UXCLUMPY . We compare the results of the different models and methods and find that the N H,l.o.s is consistently measured in each case. Three of the sources were also observed with XMM-Newton, allowing the opportunity to search for variability in soft X-ray flux or N H,l.o.s . From this sample, we find one strong CT candidate (NGC 5759) and one weaker CT candidate (CGCG 1822.3+2053). Furthermore, we find tentative evidence of N H,l.o.s variability in 2MASX J17253053–4510279, which has N H,l.o.s < 10 22 cm −2 .}, archive = {J_ApJ}, author = {Isaiah S. Cox and Núria Torres-Albà and Stefano Marchesi and Peter Boorman and Xiurui Zhao and Ross Silver and Marco Ajello and Indrani Pal}, doi = {10.3847/1538-4357/ad9c72}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {130}, shortjournal = {The Astrophys. J.}, title = {Chandra follow-up observations of swift-BAT-selected AGNs III}, volume = {979}, year = {2025}, }
• (2025). Figuring out gas and galaxies in enzo (FOGGIE). VIII. complex and stochastic metallicity gradients at z > 2. ApJ, 979(2), 129. (www)

  @article{ , abstract = {Gas-phase metallicity gradients are a crucial element in understanding the chemical evolution of galaxies. We use the FOGGIE simulations to study the metallicity gradients (∇ Z ) of six Milky Way–like galaxies throughout their evolution. FOGGIE galaxies generally exhibit steep negative gradients for most of their history, with only a few short-lived instances reaching positive slopes that appear to arise mainly from interactions with other galaxies. FOGGIE concurs with other simulation results but disagrees with the robust observational finding that flat and positive gradients are common at z > 1. By tracking the metallicity gradient at a rapid cadence of simulation outputs (∼5–10 Myr), we find that theoretical gradients are highly stochastic: the FOGGIE galaxies spend ∼30%–50% of their time far away from a smoothed trajectory inferred from analytic models or other, less high-cadence simulations. This rapid variation makes instantaneous gradients from observations more difficult to interpret in terms of physical processes. Because of these geometric and stochastic complications, we explore nonparametric methods of quantifying the evolving metallicity distribution at z > 1. We investigate how efficiently nonparametric measures of the 2D metallicity distribution respond to metal production and mixing. Our results suggest that new methods of quantifying and interpreting gas-phase metallicity will be needed to relate trends in upcoming high- z James Webb Space Telescope observations with the underlying physics of gas accretion, expulsion, and recycling in early galaxies.}, archive = {J_ApJ}, author = {Ayan Acharyya and Molly S. Peeples and Jason Tumlinson and Brian W. O’Shea and Cassandra Lochhaas and Anna C. Wright and Raymond C. Simons and Ramona Augustin and Britton D. Smith and Eugene Hyeonmin Lee}, doi = {10.3847/1538-4357/ad9dd8}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {129}, shortjournal = {The Astrophys. J.}, title = {Figuring out gas and galaxies in enzo (FOGGIE). VIII. complex and stochastic metallicity gradients at z > 2}, volume = {979}, year = {2025}, }
• (2025). Simulations of eccentricity growth in compact binary accretion disks with magnetohydrodynamic turbulence. ApJ, 979(2), 128. (www)

  @article{ , abstract = {We present the results of four magnetohydrodynamic simulations and one alpha-disk simulation of accretion disks in a compact binary system, neglecting vertical stratification and assuming a locally isothermal equation of state. We demonstrate that in the presence of a net vertical field, disks that extend out to the 3:1 mean-motion resonance grow eccentricity in full MHD in much the same way as in hydrodynamical disks. Hence, turbulence due to the magnetorotational instability (MRI) does not impede the tidally driven growth of eccentricity in any meaningful way. However, we find two important differences with alpha-disk theory. First, in MHD, eccentricity builds up in the inner disk with a series of episodes of radial disk-breaking into two misaligned eccentric disks, separated by a region of circular orbits. Standing eccentric waves are often present in the inner eccentric disk. Second, the successful spreading of an accretion disk with MRI turbulence out to the resonant radius is nontrivial—and much harder than spreading an alpha disk. This is due to the tendency to develop overdense rings in which tidal torques overwhelm MRI transport and truncate the disk too early. We believe that the inability to spread the disk sufficiently was the reason why our previous attempt to excite eccentricity via the 3:1 mean-motion resonance with MHD failed. Exactly how MHD disks successfully spread outward in compact binary systems is an important problem that has not yet been understood.}, archive = {J_ApJ}, author = {Morgan Ohana and Yan-Fei Jiang and Omer Blaes and Bryance Oyang}, doi = {10.3847/1538-4357/ad9ddb}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {128}, shortjournal = {The Astrophys. J.}, title = {Simulations of eccentricity growth in compact binary accretion disks with magnetohydrodynamic turbulence}, volume = {979}, year = {2025}, }
• (2025). Physical pathways for JWST-observed supermassive black holes in the early universe. ApJ, 979(2), 127. (www)

  @article{ , abstract = {Observations with the James Webb Space Telescope (JWST) have revealed active galactic nuclei (AGN) powered by supermassive black holes (SMBHs) with estimated masses of 10 7 –10 8 M ⊙ at redshifts z ∼ 7–9. Some reside in overmassive systems with higher AGN to stellar mass ratios than locally. Understanding how massive black holes could form so early in cosmic history and affect their environment to establish the observed relations today are some of the major open questions in astrophysics and cosmology. One model to create these massive objects is through direct collapse black holes (DCBHs) that provide massive seeds (∼10 5 –10 6 M ⊙ ), able to reach high masses in the limited time available. We use the cosmological simulation code GIZMO to study the formation and growth of DCBH seeds in the early Universe. To grow the DCBHs, we implement a gas swallowing model set to match the Eddington accretion rate as long as the nearby gaseous environment, affected by stellar and accretion disk feedback, provides sufficient fuel. We find that to create massive AGN in overmassive systems at high redshifts, massive seeds accreting more efficiently than the fiducial Bondi–Hoyle model are needed. We assess whether the conditions for such enhanced accretion rates are realistic by considering limits on plausible transport mechanisms. We also examine various DCBH growth histories and find that mass growth is more sustained in overdense cosmological environments, where high gas densities are achieved locally. We discuss the exciting prospect to directly probe the assembly history of the first SMBHs with upcoming, ultradeep JWST surveys.}, archive = {J_ApJ}, author = {Junehyoung Jeon and Volker Bromm and Boyuan Liu and Steven L. Finkelstein}, doi = {10.3847/1538-4357/ad9f3a}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {127}, shortjournal = {The Astrophys. J.}, title = {Physical pathways for JWST-observed supermassive black holes in the early universe}, volume = {979}, year = {2025}, }
• (2025). Radial-dependent responsivity of broad-line regions in active galactic nuclei: Observational consequences for reverberation mapping and black hole mass measurements. ApJ, 979(2), 126. (www)

  @article{ , abstract = {The reverberation mapping (RM) technique has seen wide applications in probing geometry and kinematics of broad-line regions (BLRs) and measuring masses of supermassive black holes (SMBHs) in active galactic nuclei. However, key quantities in RM analysis such as emissivity, responsivity, transfer functions, and mean and rms spectra are fragmentally defined in the literature and largely lack a unified formulation. Here we establish a rigorous framework for BLR RM and include a locally dependent responsivity according to photoionization calculations. The mean and rms spectra are analytically expressed with emissivity- and responsivity-weighted transfer functions, respectively. We demonstrate that the rms spectrum is proportional to the responsivity-weighted transfer function only when the continuum variation timescale is much longer than the typical extension in time delay of the BLR; otherwise, biases arise in the obtained rms line widths. The long-standing phenomenon pertaining to the different shapes between the mean and rms spectra can be explained by a radial-increasing responsivity of BLRs. The debate on the choice of emission-line widths for SMBH mass measurements is explored, and the virial factors are suggested to also depend on the luminosity states, in addition to the geometry and kinematics of BLRs.}, archive = {J_ApJ}, author = {Yan-Rong Li and Jian-Min Wang}, doi = {10.3847/1538-4357/ad9fee}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {126}, shortjournal = {The Astrophys. J.}, title = {Radial-dependent responsivity of broad-line regions in active galactic nuclei: Observational consequences for reverberation mapping and black hole mass measurements}, volume = {979}, year = {2025}, }
• (2025). Exploring variation of double-peak broad-line profile in strongly variable AGNs. ApJ, 979(2), 125. (www)

  @article{ , abstract = {The geometry and kinematics of the broad-line region (BLR) in active galactic nuclei (AGNs) are still unclear, which is crucial for studying the physics and evolution of supermassive black holes and AGNs. The broad-line profile provides valuable information on BLR geometry and kinematics. In this work, we explore the evolution of line profiles in variable AGNs based on the BLR model of Czerny and Hryniewicz, where the BLR is driven by the radiation pressure acting on dust at the surface layers of the accretion disk. The line profiles in the low-Eddington-ratio regime show a double-peak profile, which will become a single peak at high Eddington ratios. The high metallicity of Z ≳ 5 Z ⊙ is required to reproduce the observational anticorrelation between the peak separation of broad lines and the Eddington ratio for a sample of AGNs. For the broad lines in variable AGNs, it will take several years to several decades to change their line profile if the disk luminosity suffers strong variation in a much shorter timescale. More monitoring of the broad line and continuum in strongly variable AGNs can shed special light on BLR physics.}, archive = {J_ApJ}, author = {Jiancheng Wu and Qingwen Wu and Kai-Xing Lu and Xinwu Cao and Xiangli Lei and Mengye Wang and Xiao Fan}, doi = {10.3847/1538-4357/ada271}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {125}, shortjournal = {The Astrophys. J.}, title = {Exploring variation of double-peak broad-line profile in strongly variable AGNs}, volume = {979}, year = {2025}, }
• (2025). High-resolution BOES spectroscopy of raman-scattered he iiλ6545 in young planetary nebulae. ApJ, 979(2), 124. (www)

  @article{ , abstract = {Young planetary nebulae (PNe) are characterized by their hot central stars and the presence of abundant neutral and molecular components, which result from significant mass loss during the asymptotic giant branch phase of stellar evolution. Far-UV He ii λ 1025 line photons produced near the central star can undergo Raman scattering by hydrogen atoms, creating a broad emission feature centered at ~6545 Å. We conducted high-resolution spectroscopy of 12 young PNe from 2019 April to 2020 March using the Bohyunsan Observatory Echelle Spectrograph. Building on the study by Choi and Lee, who identified Raman-scattered He ii at 6545 Å in NGC 6881 and NGC 6886, we report new detections of this feature in NGC 6741 and NGC 6884. Profile fitting reveals that the velocity of the H i component relative to the He ii emission region ranges from 26 to 33 km s −1 in these PNe. Using photoionization modeling, we estimate the line flux of He ii λ 1025 and derive Raman conversion efficiencies of 0.39, 0.21, 0.24, and 0.07 for NGC 6881, NGC 6741, NGC 6886, and NGC 6884, respectively. These results, combined with radiative transfer modeling, suggest the presence of H i components with masses around 10 −2 M ⊙ , moving outward from the central He ii emission region at speeds characteristic of the slow stellar wind from a mass-losing giant star.}, archive = {J_ApJ}, author = {Jin Lim and Seok-Jun Chang and Jaejin Shin and Hee-Won Lee and Jiyu Kim and Hak-Sub Kim and Bo-Eun Choi and Ho-Gyu Lee}, doi = {10.3847/1538-4357/ada273}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {124}, shortjournal = {The Astrophys. J.}, title = {High-resolution BOES spectroscopy of raman-scattered he iiλ6545 in young planetary nebulae}, volume = {979}, year = {2025}, }
• (2025). The microlensing event rate and optical depth from MOA-II 9 yr survey toward the galactic bulge. ApJ, 979(2), 123. (www)

  @article{ , abstract = {We present measurements of the microlensing optical depth and event rate toward the Galactic bulge using the data set from the 2006 to 2014 MOA-II survey, which covers 22 bulge fields spanning ∼42 deg 2 between −5° < l < 10° and −7° < b < −1°. In the central region with ∣ l ∣ < 5°, we estimate an optical depth of \tau =[1.75\pm 0.04]\times 1{0}^{-6}\exp [(0.34\pm 0.02)({3}^{\circ }-| b| )] and an event rate of Γ = [16.08 ± 0.28] × 10 −6 \exp [(0.44\pm 0.02)({3}^{\circ }-| b| )]{\mathrm{star}}^{-1}\,{\mathrm{yr}}^{-1} using a sample consisting of 3525 microlensing events, with Einstein radius crossing times of t E < 760 days and a source star magnitude of I s < 21.4 mag. We confirm our results are consistent with the latest measurements from the OGLE-IV 8 yr data set. We find our result is inconsistent with a prediction based on Galactic models, especially in the central region with ∣ b ∣ < 3°. These results can be used to improve the Galactic bulge model, and more central regions can be further elucidated by upcoming microlensing experiments, such as the PRime-focus Infrared Microlensing Experiment and Nancy Grace Roman Space Telescope.}, archive = {J_ApJ}, author = {Kansuke Nunota and Takahiro Sumi and Naoki Koshimoto and Nicholas J. Rattenbury and Fumio Abe and Richard Barry and David P. Bennett and Aparna Bhattacharya and Akihiko Fukui and Ryusei Hamada and Shunya Hamada and Naoto Hamasaki and Yuki Hirao and Stela Ishitani Silva and Yoshitaka Itow and Yutaka Matsubara and Shota Miyazaki and Yasushi Muraki and Tsutsumi Nagai and Greg Olmschenk and Clement Ranc and Yuki K. Satoh and Daisuke Suzuki and Paul. J. Tristram and Aikaterini Vandorou and Hibiki Yama and (MOA collaboration)}, doi = {10.3847/1538-4357/ada352}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {123}, shortjournal = {The Astrophys. J.}, title = {The microlensing event rate and optical depth from MOA-II 9 yr survey toward the galactic bulge}, volume = {979}, year = {2025}, }
• (2025). Deep searches for radio pulsations and bursts from four magnetar and a magnetar-like pulsar with FAST. ApJ, 979(2), 122. (www)

  @article{ , abstract = {We report on radio observations of four magnetars SGR 0501+4516, Swift 1834.9–0846, 1E 1841–045, SGR 1900+14, and a magnetar-like pulsar PSR J1846–0258 with the Five-hundred-meter Aperture Spherical radio Telescope at 1250 MHz. Notably, PSR J1846–0258 was observed 1 month after its 2020 X-ray outburst. The data from these observations were searched for periodic emissions and single pulses. No radio emission was detected for any of our targets. After accounting for the effect of red noise, the nondetections yield stringent upper limits on the radio flux density, with S 1250 ≤ 16.9 μ Jy for the four magnetars and the magnetar-like pulsar, along with constraints on single-pulse flux densities. Our deep radio observations suggest that these magnetars and the magnetar-like pulsar are indeed radio-quiet sources or unfavorably beamed. The resulting flux upper limits, along with previous findings, are discussed, highlighting the significance of further radio observations of radio-quiet magnetars and the high-B magnetar-like pulsar.}, archive = {J_ApJ}, author = {Juntao Bai and Na Wang and Shi Dai and Shuangqiang Wang and Jianping Yuan and Wenming Yan and Lunhua Shang and Xin Xu and Shijun Dang and Zhen Zhang}, doi = {10.3847/1538-4357/ada3c4}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {122}, shortjournal = {The Astrophys. J.}, title = {Deep searches for radio pulsations and bursts from four magnetar and a magnetar-like pulsar with FAST}, volume = {979}, year = {2025}, }
• (2025). Extreme heating of minor ions in imbalanced solar-wind turbulence. ApJ, 979(2), 121. (www)

  @article{ , abstract = {Minor ions in the solar corona are heated to extreme temperatures, far in excess of those of the electrons and protons that comprise the bulk of the plasma. These highly nonthermal distributions make minor ions sensitive probes of the collisionless processes that heat the corona and power the solar wind. The recent discovery of the "helicity barrier" offers a mechanism in which imbalanced Alfvénic turbulence in low- β plasmas preferentially heats protons over electrons, generating high-frequency, proton-cyclotron-resonant fluctuations. We use the hybrid-kinetic particle-in-cell code Pegasus++ to drive imbalanced Alfvénic turbulence in a 3D low- β plasma with additional passive ion species, He 2+ and O 5+ . A helicity barrier naturally develops, followed by clear phase-space signatures of oblique proton-cyclotron-wave heating and Landau-resonant heating from the imbalanced Alfvénic fluctuations. The former results in characteristically arced ion velocity distribution functions, whose non-bi-Maxwellian features are shown by linear ALPS calculations to be critical to the heating process. Additional features include a steep transition-range electromagnetic spectrum, proton-cyclotron waves propagating in the direction of the imbalance, significantly enhanced proton-to-electron heating ratios, ion temperatures that are considerably more perpendicular with respect to magnetic field, and extreme heating of heavier species in a manner consistent with mass scalings inferred from spacecraft measurements. None of these features are realized in an otherwise equivalent simulation of balanced turbulence. If seen simultaneously in the fast solar wind, these signatures of the helicity barrier would testify to the necessity of incorporating turbulence imbalance in a complete theory for the evolution of the solar wind.}, archive = {J_ApJ}, author = {Michael F. Zhang and Matthew W. Kunz and Jonathan Squire and Kristopher G. Klein}, doi = {10.3847/1538-4357/ad95fc}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {121}, shortjournal = {The Astrophys. J.}, title = {Extreme heating of minor ions in imbalanced solar-wind turbulence}, volume = {979}, year = {2025}, }
• (2025). On the formation of planets in the milky way’s thick disk. ApJ, 979(2), 120. (www)

  @article{ , abstract = {Exoplanet demographic surveys have revealed that close-in (≲1 au) small planets orbiting stars in the Milky Way's thick disk are ∼50% less abundant than those orbiting stars in the Galactic thin disk. One key difference between the two stellar populations is the time at which they emerged: thick-disk stars are the likely product of cosmic noon (redshift z ∼ 2), an era characterized by high star formation rate, massive and dense molecular clouds, and strong supersonic turbulence. Solving for the background radiation field in these early star-forming regions, we demonstrate that protoplanetary disks at cosmic noon experienced radiation fields up to ∼7 orders of magnitude more intense than in solar neighborhood conditions. Coupling the radiation field to a one-dimensional protoplanetary disk evolution model, we find that external UV photoevaporation destroys protoplanetary disks in just ∼0.2–0.5 Myr, limiting the timescale over which planets can assemble. Disk temperatures exceed the sublimation temperatures of common volatile species for ≳Myr timescales, predicting more spatial homogeneity in gas chemical composition. Our calculations imply that the deficit in planet occurrence around thick-disk stars should be even more pronounced for giant planets, particularly those at wide orbital separations, predicting a higher rocky-to-giant planet ratio in the Galactic thick disk versus thin disk.}, archive = {J_ApJ}, author = {Tim Hallatt and Eve J. Lee}, doi = {10.3847/1538-4357/ad9aa1}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {120}, shortjournal = {The Astrophys. J.}, title = {On the formation of planets in the milky way’s thick disk}, volume = {979}, year = {2025}, }
• (2025). Molecular distributions and abundances in the binary-shaped outflow of v hya. ApJ, 979(2), 119. (www)

  @article{ , abstract = {Binaries are known to play a key role in the mass loss and dynamical environments of evolved stars. Stellar and substellar companion interactions produce complex wind morphologies including rotating/expanding disks, bipolar outflows, and spiral wind patterns; however, the connection between these many structures and the gas-phase chemistry they harbor is not well constrained. To expand the sample of chemical inventories in interacting systems, we present a detailed spectroscopic case study of the binary C-rich asymptotic giant branch (AGB) star V Hya. Using spatially resolved Atacama Large Millimeter/submillimeter Array observations at Bands 3, 6, and 7, we characterize the rotational emission lines and distributions of molecules in its surrounding disk undergoing dynamical expansion (DUDE). We detect emission from over 15 molecules and isotopologues toward this source, and present resolved maps for the brightest tracers of carbonaceous chemistry (e.g., CCH, C 4 H, HC 5 N, HNC, and {\mathrm{CH}}_{3}\mathrm{CN} ). Employing LTE and non-LTE models of emission from the DUDE, we estimate the abundance distributions for optically thin species, and compare them with prototypical carbon-rich AGB envelopes. We find that the average abundances of detected species are within a factor of ∼5 from sources with similar mass-loss rates; however, the distribution of daughter species in V Hya is much more compact, with carbon chain species (CCH, C 4 H, and HC 3 N) appearing with abundances >10 −7 even in the innermost sampled regions (200 au) of the disk.}, archive = {J_ApJ}, author = {Mark A. Siebert and Raghvendra Sahai and Samantha Scibelli and Anthony J. Remijan}, doi = {10.3847/1538-4357/ad8e34}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {119}, shortjournal = {The Astrophys. J.}, title = {Molecular distributions and abundances in the binary-shaped outflow of v hya}, volume = {979}, year = {2025}, }
• (2025). The prevalence of star-forming clumps as a function of environmental overdensity in local galaxies. ApJ, 979(2), 118. (www)

  @article{ , abstract = {At the peak of cosmic star formation (1 ≲ z ≲ 2), the majority of star-forming galaxies hosted compact, star-forming clumps, which were responsible for a large fraction of cosmic star formation. By comparison, ≲5% of local star-forming galaxies host comparable clumps. In this work, we investigate the link between the environmental conditions surrounding local ( z < 0.04) galaxies and the prevalence of clumps in these galaxies. To obtain our clump sample, we use a Faster R-CNN object detection network trained on the catalog of clump labels provided by the Galaxy Zoo: Clump Scout project, then apply this network to detect clumps in approximately 240,000 Sloan Digital Sky Survey galaxies (originally selected for Galaxy Zoo 2). The resulting sample of 41,445 u -band bright clumps in 34,246 galaxies is the largest sample of clumps yet assembled. We then select a volume-limited sample of 9964 galaxies and estimate the density of their local environment using the distance to their projected fifth nearest neighbor. We find a robust correlation between environment and the clumpy fraction ( f clumpy ) for star-forming galaxies (specific star formation rate, sSFR > 10 −2 Gyr −1 ) but find little to no relationship when controlling for galaxies' sSFR or color. Further, f clumpy increases significantly with sSFR in local galaxies, particularly above sSFR > 10 −1 Gyr −1 . We posit that a galaxy's gas fraction primarily controls the formation and lifetime of its clumps, and that environmental interactions play a smaller role.}, archive = {J_ApJ}, author = {Dominic Adams and Hugh Dickinson and Lucy Fortson and Kameswara Mantha and Vihang Mehta and Jürgen Popp and Claudia Scarlata and Chris Lintott and Brooke Simmons and Mike Walmsley}, doi = {10.3847/1538-4357/ad7119}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {118}, shortjournal = {The Astrophys. J.}, title = {The prevalence of star-forming clumps as a function of environmental overdensity in local galaxies}, volume = {979}, year = {2025}, }
• (2025). The red supergiant progenitor luminosity problem. ApJ, 979(2), 117. (www)

  @article{ , abstract = {Analysis of pre-explosion imaging has confirmed red supergiants (RSGs) as the progenitors to Type II-P supernovae (SNe). However, extracting an RSG's luminosity requires assumptions regarding the star's temperature or spectral type and the corresponding bolometric correction, circumstellar extinction, and possible variability. The robustness of these assumptions is difficult to test since we cannot go back in time and obtain additional pre-explosion imaging. Here, we perform a simple test using the RSGs in M31, which have been well observed from optical to mid-IR. We ask the following: By treating each star as if we only had single-band photometry and making assumptions typically used in SN progenitor studies, what bolometric luminosity would we infer for each star? How close is this to the bolometric luminosity for that same star inferred from the full optical-to-IR spectral energy distribution (SED)? We find common assumptions adopted in progenitor studies systematically underestimate the bolometric luminosity by a factor of 2, typically leading to inferred progenitor masses that are systematically too low. Additionally, we find a much larger spread in luminosity derived from single-filter photometry compared to SED-derived luminosities, indicating uncertainties in progenitor luminosities are also underestimated. When these corrections and larger uncertainties are included in the analysis, even the most luminous known RSGs are not ruled out at the 3 σ level, indicating there is currently no statistically significant evidence that the most luminous RSGs are missing from the observed sample of II-P progenitors. The proposed correction also alleviates the problem of having progenitors with masses below the expected lower-mass bound for core collapse.}, archive = {J_ApJ}, author = {Emma R. Beasor and Nathan Smith and Jacob E. Jencson}, doi = {10.3847/1538-4357/ad8f3f}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {117}, shortjournal = {The Astrophys. J.}, title = {The red supergiant progenitor luminosity problem}, volume = {979}, year = {2025}, }
• (2025). Imaging and spectral fitting of bright gamma-ray sources with the COSI balloon payload. ApJ, 979(2), 116. (www)

  @article{ , abstract = {The Compton Spectrometer and Imager balloon payload (COSI-Balloon) is a wide field-of-view Compton gamma-ray telescope that operates in the 0.2–5 MeV bandpass. COSI-Balloon had a successful 46 day flight in 2016 during which the instrument observed the Crab Nebula, Cygnus X-1, and Centaurus A. Using the data collected by the COSI-Balloon instrument during this flight, we present the source flux extraction of signals from the variable balloon background environment and produce images of these background-dominated sources by performing Richardson–Lucy deconvolutions. We also present the spectra measured by the COSI-Balloon instrument, compare and combine them with measurements from other instruments, and fit the data. The Crab Nebula was observed by COSI-Balloon, and we obtain a measured flux in the energy band 325–480 keV of (4.5 ± 1.6) × 10 3 ph cm −2 s −1 . The model that best fits the COSI-Balloon data combined with measurements from NuSTAR and Swift-BAT is a broken power law with a measured photon index Γ = 2.20 ± 0.02 above the 43 keV break. Cygnus X-1 was also observed during this flight, and we obtain a measured flux of (1.4 ± 0.2) × 10 3 ph cm −2 s −1 in the same energy band and a best-fit result (including data from NuSTAR, Swift-BAT, and INTEGRAL/IBIS) was a cutoff power law with a high-energy cutoff energy of 138.3 ± 1.0 keV and a photon index of Γ = 1.358 ± 0.002. Finally, we present the measured spectrum of Centaurus A and our best model fit to a power law with a photon index of Γ = 1.73 ± 0.01.}, archive = {J_ApJ}, author = {Jarred M. Roberts and Steven Boggs and Thomas Siegert and John A. Tomsick and Marco Ajello and Peter von Ballmoos and Jacqueline Beechert and Floriane Cangemi and Savitri Gallego and Pierre Jean and Chris Karwin and Carolyn Kierans and Hadar Lazar and Alex Lowell and Israel Martinez Castellanos and Sean Pike and Clio Sleator and Yong Sheng and Hiroki Yoneda and Andreas Zoglauer}, doi = {10.3847/1538-4357/ad968a}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {116}, shortjournal = {The Astrophys. J.}, title = {Imaging and spectral fitting of bright gamma-ray sources with the COSI balloon payload}, volume = {979}, year = {2025}, }
• (2025). Data-driven dynamics with orbital torus imaging: A flexible model of the vertical phase space of the galaxy. ApJ, 979(2), 115. (www)

  @article{ , abstract = {The vertical kinematics of stars near the Sun can be used to measure the total mass distribution near the Galactic disk and to study out-of-equilibrium dynamics. With contemporary stellar surveys, the tracers of vertical dynamics are so numerous and so well measured that the shapes of underlying orbits are almost directly visible in the data through element abundances or even stellar density. These orbits can be used to infer a mass model for the Milky Way, enabling constraints on the dark matter distribution in the inner galaxy. Here, we present a flexible model for foliating the vertical position–velocity phase space with orbits for use in data-driven studies of dynamics. The vertical acceleration profile in the vicinity of the disk, along with the orbital actions, angles, and frequencies for individual stars, can all be derived from that orbit foliation. We show that this framework—"orbital torus imaging" (OTI)—is rigorously justified in the context of dynamical theory, and does a good job of fitting orbits to simulated stellar abundance data with varying degrees of realism. OTI (1) does not require a global model for the Milky Way mass distribution, and (2) does not require detailed modeling of the selection function of the input survey data. We discuss the approximations and limitations of the OTI framework, which currently trades dynamical interpretability for flexibility in representing the data in some regimes, and which also presently separates the vertical and radial dynamics. We release an open-source tool, torusimaging , to accompany this article.}, archive = {J_ApJ}, author = {Adrian M. Price-Whelan and Jason A. S. Hunt and Danny Horta and Micah Oeur and David W. Hogg and Kathryn Johnston and Lawrence Widrow}, doi = {10.3847/1538-4357/ad969a}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {115}, shortjournal = {The Astrophys. J.}, title = {Data-driven dynamics with orbital torus imaging: A flexible model of the vertical phase space of the galaxy}, volume = {979}, year = {2025}, }
• (2025). ATClean: A novel method for detecting low-luminosity transients and application to pre-explosion counterparts from SN 2023ixf. ApJ, 979(2), 114. (www)

  @article{ , abstract = {In an effort to search for faint sources of emission over arbitrary timescales, we present a novel method for analyzing forced photometry light curves in difference imaging from optical surveys. Our method "ATLAS Clean," or ATClean, utilizes the reported fluxes, uncertainties, and fits to the point-spread function (PSF) from difference images to quantify the statistical significance of individual measurements. We apply this method to control light curves across the image to determine whether any source of flux is present in the data for a range of specific timescales. From ATLAS o -band imaging at the site of the Type II supernova (SN) 2023ixf in M101 from 2015–2023, we show that this method accurately reproduces the 3 σ flux limits produced from other, more computationally expensive methods. We derive limits for emission on timescales of 5 days and 80–300 days at the site of SN 2023ixf, which are 19.8 and 21.3 mag, respectively. The latter limits rule out variability for unextinguished red supergiants with initial masses >22 M ⊙ , comparable to the most luminous predictions for the SN 2023ixf progenitor system. We also compare our limits to short-timescale outbursts, similar to those expected for Type IIn SN progenitor stars or the Type II SN 2020tlf, and rule out outburst ejecta masses of >0.021 M ⊙ , much lower than the inferred mass of circumstellar matter around SN 2023ixf in the literature. In the future, these methods can be applied to any forced photometry on difference imaging from other surveys, such as Rubin optical imaging.}, archive = {J_ApJ}, author = {S. Rest and A. Rest and C. D. Kilpatrick and J. E. Jencson and S. von Coelln and L. Strolger and S. Smartt and J. P. Anderson and A. Clocchiatti and D. A. Coulter and L. Denneau and S. Gomez and A. Heinze and R. Ridden-Harper and K. W. Smith and B. Stalder and J. L. Tonry and Q. Wang and Y. Zenati}, doi = {10.3847/1538-4357/ad973d}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {114}, shortjournal = {The Astrophys. J.}, title = {ATClean: A novel method for detecting low-luminosity transients and application to pre-explosion counterparts from SN 2023ixf}, volume = {979}, year = {2025}, }
• (2025). Failure of a solar filament eruption caused by magnetic reconnection with overlying coronal loops. ApJ, 979(2), 113. (www)

  @article{ , abstract = {The failure of a filament eruption caused by magnetic reconnection between the erupting filament and the overlying magnetic field has been previously proposed in numerical simulations. It is, however, rarely observed. In this study, we report a reconnection between an erupting filament and its overlying coronal loops that results in the failure of the filament eruption. On 2023 September 24, a filament was located in active region 13445. It slowly rose, quickly erupted, rapidly decelerated, then finally stopped, with an untwisting motion. As a failed eruption, the event is associated with an M4.4 flare but no coronal mass ejection. During the eruption, the filament became bright, and the overlying loops appeared first in the high-temperature channels. They have average temperatures of ∼12.8 and ∼9.6 MK, respectively, indicating that both of them were heated. Two sets of new loops, separately connecting the filament endpoints and the overlying loop footpoints, then formed. Subsequently, the heated overlying loops were seen sequentially in the low-temperature channels, showing the cooling process, which is also supported by the light curves. Plasmoids formed and propagated bidirectionally along the filament and the overlying loops, indicating the presence of plasmoid instability. These results suggest that reconnection occurs between the erupting filament and the overlying loops. The erupting filament eventually disappeared, with the appearance of more newly formed loops. We propose that the reconnection between the erupting filament and the overlying loops ruins the filament completely, hence resulting in the failed eruption.}, archive = {J_ApJ}, author = {Leping Li and Hongqiang Song and Yijun Hou and Guiping Zhou and Baolin Tan and Kaifan Ji and Yongyuan Xiang and Zhenyong Hou and Yang Guo and Ye Qiu and Yingna Su and Haisheng Ji and Qingmin Zhang and Yudi Ou}, doi = {10.3847/1538-4357/ad9a56}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {113}, shortjournal = {The Astrophys. J.}, title = {Failure of a solar filament eruption caused by magnetic reconnection with overlying coronal loops}, volume = {979}, year = {2025}, }
• (2025). Modeling high mass X-ray binaries to double neutron stars through common envelope evolution. ApJ, 979(2), 112. (www)

  @article{ , abstract = {We present detailed evolutionary simulations of wide binary systems with high-mass (8–20 M ⊙ ) donor stars and a 1.4 M ⊙ neutron star. Mass transfer in such binaries is dynamically unstable, and common envelope (CE) evolution is followed. We use a recently developed prescription to deal with CE evolution and consider various CE ejection efficiencies varying in the range of 0.1–3.0. We focus on the evolutionary consequences of the binaries that survived CE evolution. We demonstrate that it is possible for the binaries to enter a CE decoupling phase (CEDP) when the donor stars are partially stripped, leaving a hydrogen envelope of ≲1.0–4.0 M ⊙ after CE evolution. This phase is expected to last ∼10 4 –10 5 yr, during which mass transfer occurs stably via Roche lobe overflow with super-Eddington rates. Identification of some X-ray binaries in a CEDP is important for the understanding of the physics of CE evolution itself, the origin of ultraluminous X-ray sources, and the recycling process of accreting pulsars. Also, we discuss the formation of double neutron stars and the occurrence of ultrastripped supernovae according to the results from our simulations. On the whole, the properties of post-CE binaries are sensitive to the options of CE ejection efficiencies.}, archive = {J_ApJ}, author = {Yu-Dong Nie and Yong Shao and Jian-Guo He and Ze-Lin Wei and Xiao-Jie Xu and Xiang-Dong Li}, doi = {10.3847/1538-4357/ad9a65}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {112}, shortjournal = {The Astrophys. J.}, title = {Modeling high mass X-ray binaries to double neutron stars through common envelope evolution}, volume = {979}, year = {2025}, }
• (2025). The origins of lithium enhancement in polluted white dwarfs. ApJ, 979(2), 111. (www)

  @article{ , abstract = {The bulk abundances of exoplanetesimals can be measured when they are accreted by white dwarfs. Recently, lithium from the accretion of exoplanetesimals was detected in relatively high levels in multiple white dwarfs. There are presently three proposed hypotheses to explain the detection of excess lithium in white dwarf photospheres: Big Bang and Galactic nucleosynthesis, continental crust, and an exomoon formed from spalled ring material. We present new observations of three previously known lithium-polluted white dwarfs (WD J1824+1213, WD J2317+1830, and LHS 2534), and one with metal pollution without lithium (SDSS J1636+1619). We also present atmospheric model fits to these white dwarfs. We then evaluate the abundances of these white dwarfs and two additional lithium-polluted white dwarfs that were previously fit using the same atmospheric models (WD J1644-0449 and SDSS J1330+6435) in the context of the three extant hypotheses for explaining lithium excesses in polluted white dwarfs. We find Big Bang and Galactic nucleosynthesis to be the most plausible explanation of the abundances in WD J1644-0449, WD J1824+1213, and WD J2317+1830. SDSS J1330+6435 will require stricter abundances to determine its planetesimal's origins, and LHS 2534, as presently modeled, defies all three hypotheses. We find the accretion of an exomoon formed from spalled ring material to be highly unlikely to be the explanation of the lithium excess in any of these cases.}, archive = {J_ApJ}, author = {Benjamin C. Kaiser and J. Christopher Clemens and Simon Blouin and Erik Dennihy and Patrick Dufour and Ryan J. Hegedus and Joshua S. Reding}, doi = {10.3847/1538-4357/ad9a6d}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {111}, shortjournal = {The Astrophys. J.}, title = {The origins of lithium enhancement in polluted white dwarfs}, volume = {979}, year = {2025}, }
• (2025). Water ice in the edge-on orion silhouette disk 114–426 from JWST NIRCam images. ApJ, 979(2), 110. (www)

  @article{ , abstract = {We examine images of the protoplanetary disk 114–426 with JWST/NIRCam in 12 bands. This large disk is oriented edge on with a dark midplane flanked by lobes of scattered light. The outer edges of the midplane are seen in silhouette against the Orion Nebula, providing a unique opportunity to study planet-forming material in absorption. We discover a dip in the scattered light of the disk at 3 μ m—compelling evidence for the presence of water ice. The 3 μ m dip is also seen in the silhouette of the disk, where we quantify the ice abundance with models of pure absorption and avoid the complications of disk scattering effects. We find grain ice-to-refractory mass ratios of up to ~0.2, maximum grain sizes of 0.25–5 μ m, and a total dust plus ice mass of 0.46 M ⊕ in the silhouette region. We also discover excess absorption in the NIRCam bands that include the Pa α line, suggesting there may be excited atomic hydrogen in the disk. Examining the morphology of the scattered light lobes reveals that they are laterally offset from each other and exhibit a brightness asymmetry that flips with wavelength—both evidence for a tilted inner disk in this system.}, archive = {J_ApJ}, author = {Nicholas P. Ballering and L. Ilsedore Cleeves and Ryan D. Boyden and Mark J. McCaughrean and Rachel E. Gross and Samuel G. Pearson}, doi = {10.3847/1538-4357/ad9b7a}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {110}, shortjournal = {The Astrophys. J.}, title = {Water ice in the edge-on orion silhouette disk 114–426 from JWST NIRCam images}, volume = {979}, year = {2025}, }
• (2025). Interaction of an outflow with surrounding gaseous clouds as the origin of late-time radio flares in tidal disruption events. ApJ, 979(2), 109. (www)

  @article{ , abstract = {Close encounter between a star and a supermassive black hole (SMBH) results in the tidal disruption of the star, known as a tidal disruption event (TDE). Recently, a few TDEs, e.g., ASASSN-15oi and AT2018hyz, have shown late-time (hundreds of days after their UV/optical peaks) radio flares with radio luminosities of 10 38∼39 erg s −1 . The super-Eddington fallback or accretion in a TDE may generate a mass outflow. Here, we investigate a scenario that the late-time radio flares come from the interaction of the outflow with the circumnuclear gaseous clouds, in addition to the slow-evolving emission component due to the outflow–diffuse medium interaction. We calculate the associated radio temporal and spectral signatures and find that they reproduce well the observations. The outflows have the inferred velocity of 0.2 c ∼ 0.6 c , the total mass of 10 −3 ∼ 10 −1 M ⊙ and the ejection duration of a month to a year. The distances of the clouds to the SMBH are 0.1 ∼ 1 pc. This scenario has advantages in explaining the long delay, sharpness of the rise, and the multiplicity of the late radio flares. Future observations may build up a much larger sample of late-time radio flares and enable their use as a probe of the TDE physics and the host circumnuclear environment.}, archive = {J_ApJ}, author = {Jialun Zhuang and Rong-Feng Shen and Guobin Mou and Wenbin Lu}, doi = {10.3847/1538-4357/ad9b98}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {109}, shortjournal = {The Astrophys. J.}, title = {Interaction of an outflow with surrounding gaseous clouds as the origin of late-time radio flares in tidal disruption events}, volume = {979}, year = {2025}, }
• (2025). Discoveries and properties of EL CVn–type binaries in the TESS survey. ApJ, 979(2), 108. (www)

  @article{ , abstract = {EL CVn–type systems represent a rare evolutionary stage in binary star evolution, providing ideal laboratories for investigating stable mass-transfer processes and the formation of extremely low-mass white dwarfs (ELM WDs). The Transiting Exoplanet Survey Satellite (TESS) has delivered an extensive collection of high-precision time-domain photometric data, which is invaluable for studying EL CVn binaries. In this study, we identified 29 EL CVn systems from the TESS eclipsing binary catalogs (sectors 1–65), 11 of which are newly discovered. These systems consist of smaller, hotter prehelium WDs and A/F main-sequence stars. The orbital periods of these binaries range from 0.64 to 2.5 days. Utilizing TESS light curves, Gaia distances, and multiband photometric data (e.g., Galaxy Evolution Explorer, Two Micron All Sky Survey, Wide-field Infrared Survey Explorer, SkyMapper), we modeled the light curves and spectral energy distributions to derive system parameters, including effective temperatures, masses, and radii. These systems were then compared with the WD mass–period relation and the evolutionary tracks of ELM WDs. The comparison reveals that these binaries are consistent with the expected mass–period relation for WDs and align well with the evolutionary tracks on the T eff − \mathrm{log}g diagram for ELM WDs. This result suggests that these EL CVn systems likely formed through stable mass-transfer processes. We provide a catalog of complete parameters for 29 EL CVn systems identified from the TESS survey. This catalog will serve as an essential resource for studying binary mass transfer, WD formation, and pulsation phenomena in EL CVn–type systems.}, archive = {J_ApJ}, author = {Jianping Xiong and Zhenwei Li and Jiao Li and Xiaobin Zhang and Xiaodian Chen and Kaifan Ji and Zhanwen Han and Xuefei Chen}, doi = {10.3847/1538-4357/ad9b9c}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {108}, shortjournal = {The Astrophys. J.}, title = {Discoveries and properties of EL CVn–type binaries in the TESS survey}, volume = {979}, year = {2025}, }
• (2025). Photometric selection of type 1 quasars in the XMM-LSS field with machine learning and the Disk–Corona connection. ApJ, 979(2), 107. (www)

  @article{ , abstract = {We present photometric selection of type 1 quasars in the ≈5.3 deg 2 XMM-Large Scale Structure survey field with machine learning. We constructed our training and blind-test samples using spectroscopically identified Sloan Digital Sky Survey quasars, galaxies, and stars. We utilized the XGBoost machine learning method to select a total of 1591 quasars. We assessed the classification performance based on the blind-test sample, and the outcome was favorable, demonstrating high reliability (≈99.9%) and good completeness (≈87.5%). We used XGBoost to estimate photometric redshifts of our selected quasars. The estimated photometric redshifts span a range from 0.41 to 3.75. The outlier fraction of these photometric redshift estimates is ≈17%, and the normalized median absolute deviation ( σ NMAD ) is ≈0.07. To study the quasar disk–corona connection, we constructed a subsample of 1016 quasars with Hyper Suprime-Cam i < 22.5 after excluding radio-loud and potentially X-ray-absorbed quasars. The relation between the optical-to-X-ray power-law slope parameter ( α OX ) and the 2500 Å monochromatic luminosity ( L 2500Å ) for this subsample is {\alpha }_{{\rm{OX}}}=(-0.156\pm 0.007)\,{\rm{log}}\,{L}_{2500\,\mathring{\rm A} }+(3.175\pm 0.211) with a dispersion of 0.159. We found this correlation in good agreement with the correlations in previous studies. We explored several factors, which may bias the α OX – L 2500Å relation, and found that their effects are not significant. We discussed possible evolution of the α OX – L 2500Å relation with respect to L 2500Å or redshift.}, archive = {J_ApJ}, author = {Jian Huang and Bin Luo and W. N. Brandt and Ying Chen and Qingling Ni and Yongquan Xue and Zijian Zhang}, doi = {10.3847/1538-4357/ad9baf}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {107}, shortjournal = {The Astrophys. J.}, title = {Photometric selection of type 1 quasars in the XMM-LSS field with machine learning and the Disk–Corona connection}, volume = {979}, year = {2025}, }
• (2025). Interplay of large-scale drift and turbulence in the heliospheric propagation of solar energetic particles. ApJ, 979(2), 106. (www)

  @article{ , abstract = {The gradient and curvature of the Parker spiral interplanetary magnetic field give rise to curvature and gradient guiding-center drifts on cosmic rays (CRs). The plasma turbulence present in interplanetary space is thought to suppress the drifts; however, the extent to which they are reduced is not clear. We investigate the reduction of the drifts using a new analytic model of heliospheric turbulence where the dominant 2D component has both a wavevector and magnetic field vector normal to the Parker spiral, thus fulfilling the main criterion of 2D turbulence. We use full-orbit test-particle simulations of energetic protons in the modeled interplanetary turbulence, and analyze the mean drift velocity of the particles in heliolatitude. We release energetic proton populations of 10, 100, and 1000 MeV close to the Sun and introduce a new method to assess their drift. We compare the drift in the turbulent heliosphere to drift in a configuration without turbulence, and to theoretical estimates of drift reduction. We find that drifts are reduced by a factor 0.2–0.9 of that expected for the heliospheric configuration without turbulence. This corresponds to a much less efficient suppression than what is predicted by theoretical estimates, particularly at low proton energies. We conclude that guiding-center drifts are a significant factor for the evolution of CR intensities in the heliosphere, including the propagation of solar energetic particles in the inner heliosphere.}, archive = {J_ApJ}, author = {T. Laitinen and S. Dalla}, doi = {10.3847/1538-4357/ad9c3b}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {106}, shortjournal = {The Astrophys. J.}, title = {Interplay of large-scale drift and turbulence in the heliospheric propagation of solar energetic particles}, volume = {979}, year = {2025}, }
• (2025). The first exploration of the correlations between WISE 12 μm and CO emission in early-type galaxies. ApJ, 979(2), 105. (www)

  @article{ , abstract = {We present the analysis of a comprehensive sample of 352 early-type galaxies using public data, to investigate the correlations between CO luminosities and mid-infrared luminosities observed by Wide-field Infrared Survey Explorer. We find strong correlations between both CO (1–0) and CO (2–1) luminosities and 12 μ m luminosity, boasting a correlation coefficient greater than 0.9 and an intrinsic scatter smaller than 0.1 dex. The consistent slopes observed for the relationships of CO (1–0) and CO (2–1) suggest that the line ratio R 21 lacks correlation with mid-infrared emission in early-type galaxies, which is significantly different from star-forming galaxies. Moreover, the slopes of L CO(1−0) – L 12 μ m and L CO(2−1) – L 12 μ m relations in early-type galaxies are steeper than those observed in star-forming galaxies. Given the absence of correlation with color, morphology, or specific star formation rate (sSFR), the correlation between deviations and the molecular gas mass surface density could be eliminated by correcting the possible 12 μ m emission from old stars or adopting a systematically different α CO . The latter, on average, is equivalent to adding a constant CO brightness density, specifically 2.{8}_{-0.6}^{+0.8}\,[{\rm{K}}\,{\rm{km}}\,{{\rm{s}}}^{-1}] and 4.{4}_{-1.4}^{+2.2}\,[{\rm{K}}\,{\rm{km}}\,{{\rm{s}}}^{-1}] for CO (1–0) and (2–1), respectively. These explorations will serve as useful tools for estimating the molecular gas content in gas-poor galaxies and understanding associated quenching processes.}, archive = {J_ApJ}, author = {Yang Gao and Enci Wang and Qing-Hua Tan and Timothy A. Davis and Fu-Heng Liang and Xue-Jian Jiang and Ning Gai and Qian Jiao and DongDong Shi and Shuai Feng and Yanke Tang and Shijie Li and Yi-Fan Wang}, doi = {10.3847/1538-4357/ad9d0f}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {105}, shortjournal = {The Astrophys. J.}, title = {The first exploration of the correlations between WISE 12 μm and CO emission in early-type galaxies}, volume = {979}, year = {2025}, }
• (2025). Collisionless tearing instability in relativistic nonthermal pair plasma and its application to MHD turbulence. ApJ, 979(2), 104. (www)

  @article{ , abstract = {Collisionless tearing instability with a power-law distribution function in a relativistic pair plasma with a guide field is studied. When the current sheet is supported by plasma pressure, the tearing mode is suppressed as the particle spectrum hardens. In the force-free limit, the instability growth rate becomes independent of the particle spectrum. We apply these results to relativistic MHD turbulence, where magnetic energy greatly exceeds plasma rest energy, and derive an expression for the transverse size of turbulent eddies unstable to tearing mode. We also establish the critical plasma magnetization parameter above which charge starvation prevents the tearing instability. These results might be useful for developing more accurate models of particle acceleration in relativistic astrophysical sources.}, archive = {J_ApJ}, author = {Ivan Demidov and Yuri Lyubarsky}, doi = {10.3847/1538-4357/ad9d3a}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {104}, shortjournal = {The Astrophys. J.}, title = {Collisionless tearing instability in relativistic nonthermal pair plasma and its application to MHD turbulence}, volume = {979}, year = {2025}, }
• (2025). The Age–Velocity dispersion relations of the galactic disk as revealed by the LAMOST-gaia red clump stars. ApJ, 979(2), 103. (www)

  @article{ , abstract = {Using nearly 230,000 red clump stars selected from LAMOST and Gaia, we conduct a comprehensive analysis of the stellar age–velocity dispersion relations (AVRs) for various disk populations, within 5.0 ≤ R ≤ 15.0 kpc and ∣ Z ∣ ≤ 3.0 kpc. The AVRs of the whole red clump sample stars are accurately described as σ v = σ v ,0 ( τ + 0.1) {}^{{\beta }_{v}} , with β R , β ϕ , and β Z displaying a global exponential decreasing trend with R , which may point to the difference in spatial distributions of various disk heating mechanisms. The measurements of β – R for various disks suggest that the thin disk exhibits a radial dependence, with a global exponential decreasing trend in β R – R and β Z – R , while β ϕ remains a nearly constant value (around 0.20 ∼ 0.25) within 8.5 ≤ R ≤ 11.5 kpc. The thick disk displays a global increasing trend in β R – R , β ϕ – R , and β Z – R . These results indicate that the thin disk stars are likely heated by long-term heating from giant molecular clouds and spiral arms, while thick disk stars are likely heated by some violent heating process from merger and accretion, and/or formed by the inside-out and upside-down star formation scenarios, and/or born in the chaotic mergers of gas-rich systems and/or turbulent interstellar medium. Our results also suggest that the disk perturbation by a recent minor merger from Sagittarius may have occurred within 3.0 Gyr.}, archive = {J_ApJ}, author = {Weixiang Sun and Han Shen and Biwei Jiang and Xiaowei Liu}, doi = {10.3847/1538-4357/ad9d41}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {103}, shortjournal = {The Astrophys. J.}, title = {The Age–Velocity dispersion relations of the galactic disk as revealed by the LAMOST-gaia red clump stars}, volume = {979}, year = {2025}, }
• (2025). On the use of galaxy catalogs in gravitational-wave parameter estimation. ApJ, 979(2), 102. (www)

  @article{ , abstract = {A major challenge in gravitational-wave (GW) multimessenger astrophysics is the imprecise localization of GW compact binary mergers. We investigate the use of a method to include galaxy catalog information in performing parameter estimation of these events. We test its effectiveness with the GW events GW170817, GW190425, and GW190814, as well as with simulated binary neutron star mergers. For GW170817, we recover the true host galaxy as the most probable galaxy after a straightforward mass reweighting, with significantly decreased localization area and volume. On the simulated sample, however, we do not find improvement compared to performing a simple galaxy catalog crossmatch with a regular GW localization. Future investigations into sampling methods may yield improvements that increase the viability of this method.}, archive = {J_ApJ}, author = {Geoffrey Mo and Carl-Johan Haster and Erik Katsavounidis}, doi = {10.3847/1538-4357/ad9f36}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {102}, shortjournal = {The Astrophys. J.}, title = {On the use of galaxy catalogs in gravitational-wave parameter estimation}, volume = {979}, year = {2025}, }
• (2025). An exceptionally powerful, radiatively driven ultrafast outflow in the rapidly accreting AGN RE j1034+396. ApJ, 979(2), 101. (www)

  @article{ , abstract = {We report the analysis of ∼1 Ms of XMM-Newton observations of the rapidly accreting active galactic nucleus RE J1034+396. The 0.3–9 keV EPIC-pn spectra are well described by a model consisting of steep continuum emission from the corona accompanied by relativistically blurred reflection from a highly ionized accretion disk. The source is known to exhibit strong excess soft X-ray emission, which we show is well represented by thermal disk photons Comptonized by a warm plasma spanning the inner accretion flow. Additionally, the EPIC-pn data provide compelling evidence (Δ C ∼ 60 for four additional parameters) for the presence of an ultrafast outflow (UFO) with a line-of-sight velocity v/c=0.30{7}_{-0.005}^{+0.001} , and an emission signature consistent with reflection of the corona from modestly ionized, outflowing gas. The simultaneous 0.5–2.5 keV RGS spectra show clear absorption lines. Modelling of these data confirms the presence of the UFO and constrains its equivalent hydrogen column density, log N H /(atom cm −2 ) = {21.7}_{-0.2}^{+0.1} . The RGS data also reveal at least two warm absorber components with a modest outflow velocity ( 168{0}_{-50}^{+40} km s −1 ). The measured properties and time evolution of the UFO in RE J1034+396 suggest that it is formed from collisionally ionized plasma, launched from the disk surface and accelerated by radiation pressure. The high terminal velocity and substantial absorbing column density imply that the outflow carries sufficient momentum and energy to transform its environment, being capable of driving out essentially all dust and gas it interacts with along the line of sight, even if the AGN were initially surrounded by a Compton-thick absorber.}, archive = {J_ApJ}, author = {Chloe S. Taylor and Daniel R. Wilkins and Steven W. Allen}, doi = {10.3847/1538-4357/ad9f3e}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {101}, shortjournal = {The Astrophys. J.}, title = {An exceptionally powerful, radiatively driven ultrafast outflow in the rapidly accreting AGN RE j1034+396}, volume = {979}, year = {2025}, }
• (2025). Shock and SEP modeling study for the 2022 september 5 SEP event. ApJ, 979(2), 100. (www)

  @article{ , abstract = {On 2022 September 5, during Parker Solar Probe's (PSP) 13th encounter, a fast shock wave and a related solar energetic particle (SEP) event were observed as the spacecraft approached the perihelion of its orbit. Observations from the Integrated Science Investigation of the Sun (IS⊙IS) instrument suite show that SEPs arrived at the spacecraft with a significant delay from the onset of the parent solar eruption and that the first arriving SEPs exhibited an inverse velocity dispersion (IVD) for energetic protons above ~1 MeV. Utilizing data from multiple spacecraft, we investigate the eruption dynamics and shock wave propagation. Our analysis includes 3D shock modeling and SEP transport simulations to examine the origins of this SEP event and explore the causes of the delayed SEP onset and the observed IVD. The data-driven SEP simulation reproduces the SEP event onset observed at PSP, its evolving energy spectrum, and the IVD. This IVD is attributed to a relatively slow, ongoing particle acceleration process occurring at the flank of the expanding shock wave intercepted by PSP. This has significant implications for the role of shocks in the release of SEPs at widespread events and for methods used to infer the SEP release times. Furthermore, the match between the simulation and observations worsens when cross-field diffusion is considered, indicating that SEP diffusion had a minor effect on this event. These findings underscore the complexity of SEP events and emphasize the need for advanced modeling approaches to better understand the role of shock waves and other physical processes in SEP acceleration and release.}, archive = {J_ApJ}, author = {A. Kouloumvakos and N. Wijsen and I. C. Jebaraj and A. Afanasiev and D. Lario and C. M. S. Cohen and P. Riley and D. G. Mitchell and Z. Ding and A. Vourlidas and J. Giacalone and X. Chen and M. E. Hill}, doi = {10.3847/1538-4357/ada0be}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {100}, shortjournal = {The Astrophys. J.}, title = {Shock and SEP modeling study for the 2022 september 5 SEP event}, volume = {979}, year = {2025}, }
• (2025). The fate of oceans on first-generation planets orbiting white dwarfs. ApJ, 979(2), 99. (www)

  @article{ , abstract = {Several groups have recently suggested that small planets orbiting very closely around white dwarf stars could be promising locations for life to arise, even after stellar death. There are still many uncertainties, however, regarding the existence and habitability of these worlds. Here we consider the retention of water during post-main-sequence evolution of a Sun-like star and during the subsequent migration of planets to the white dwarf's habitable zone. This inward migration is driven by dynamical mechanisms such as planet–planet interactions in packed systems, which can excite planets to high eccentricities, setting the initial conditions for tidal migration into short-period orbits. In order for water to persist on the surfaces of planets orbiting white dwarfs, the water must first survive the asymptotic giant branch phase of stellar evolution, then avoid being lost as a result of photoevaporation due to X-ray and extreme-ultraviolet radiation from the newly formed white dwarf, and finally survive the tidal migration of the planet inward to the habitable zone. We find that while this journey will likely desiccate large swaths of post-main-sequence planetary systems, planets with substantial reservoirs of water may retain some surface water, especially if their migration occurs at later white dwarf cooling ages. Therefore, although stellar evolution may pose a challenge for the retention of water on exoplanet surfaces, it is possible for planets to retain surface oceans even as their host stars die and their orbits evolve.}, archive = {J_ApJ}, author = {Juliette Becker and Andrew Vanderburg and Joseph R. Livesey}, doi = {10.3847/1538-4357/ada149}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {99}, shortjournal = {The Astrophys. J.}, title = {The fate of oceans on first-generation planets orbiting white dwarfs}, volume = {979}, year = {2025}, }
• (2025). Are stars really ingesting their planets? examining an alternative explanation. ApJ, 979(2), 98. (www)

  @article{ , abstract = {Numerous stars exhibit surprisingly large variations in their refractory element abundances, often interpreted as signatures of planetary ingestion events. In this study, we propose that differences in the dust-to-gas ratio near stars during their formation can produce similar observational signals. We investigate this hypothesis using a suite of radiation-dust-magnetohydrodynamic STAR FORmation in Gaseous Environments (or STARFORGE) simulations of star formation. Our results show that the distribution of refractory abundance variations (Δ[X/H]) has extended tails, with about 10%–30% of all stars displaying variations around ∼0.1 dex. These variations are comparable to the accretion of 2–5 M ⊕ of planetary material into the convective zones of Sun-like stars. The width of the distributions increases with the incorporation of more detailed dust physics, such as radiation pressure and back-reaction forces, as well as with larger dust grain sizes and finer resolutions. Furthermore, our simulations reveal no correlation between Δ[X/H] and stellar separations, suggesting that dust-to-gas fluctuations likely occur on scales smaller than those of wide binaries. These findings highlight the importance of considering dust dynamics as a potential source of the observed chemical enrichment in stars.}, archive = {J_ApJ}, author = {Nadine H. Soliman and Philip F. Hopkins}, doi = {10.3847/1538-4357/ada1d5}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {98}, shortjournal = {The Astrophys. J.}, title = {Are stars really ingesting their planets? examining an alternative explanation}, volume = {979}, year = {2025}, }
• (2025). DA 362: A gamma-ray-emitting compact symmetric object. ApJ, 979(2), 97. (www)

  @article{ , abstract = {The γ -ray detection from an astrophysical object indicates the presence of an extreme environment where high-energy radiation is produced. With the continuous monitoring of the γ -ray sky by the Fermi Large Area Telescope (LAT) leading to deeper sensitivity, high-energy γ -ray emission has now been detected from a diverse class of jetted active galactic nuclei (AGNs). Here, we present the results of a multiwavelength study of the radio source DA 362, which was reported to be a blazar candidate of uncertain type. However, it was recently identified as a bona fide compact symmetric object (CSO) based on its subkiloparsec, bipolar radio morphology, and lack of radio variability. This makes DA 362 only the fourth γ -ray-emitting object of this enigmatic class of radio-loud AGNs. Using five very-long-baseline interferometry observations covering 1996–2018, we found the jet separation velocity to be subluminal ( v app ~ 0.2 c ), thus supporting its CSO nature. Its Fermi-LAT observations revealed a γ -ray flaring activity, a phenomenon never detected from the other three γ -ray-detected CSOs. This object is bright in the near-infrared band but extremely faint in the optical-UV filters, hinting at possible obscuration. Swift X-Ray Telescope observation of DA 362 reveals an extremely hard X-ray spectrum, though a strong claim cannot be made due to large uncertainties. We conclude that deeper observations are needed to probe the broadband properties of this enigmatic object and to understand the origin of high-energy γ -ray emission.}, archive = {J_ApJ}, author = {Subhashree Swain and Vaidehi S. Paliya and D. J. Saikia and C. S. Stalin}, doi = {10.3847/1538-4357/ada1d7}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {97}, shortjournal = {The Astrophys. J.}, title = {DA 362: A gamma-ray-emitting compact symmetric object}, volume = {979}, year = {2025}, }
• (2025). Autogenous electron acceleration by ion flow vortex in space plasmas. ApJ, 979(2), 96. (www)

  @article{ , abstract = {Plasma flow vortexes are ubiquitous in space and astrophysical settings and play a vital role in energy and mass transport, contributing to formation of stars and planets, launching and dissipation of astrophysical jets, and coupling between planetary magnetospheres and ionospheres. Here we present in situ observations showing that energetic electrons with energies up to 250 keV can be directly generated inside an ion flow vortex with finite spatial scale. The electron acceleration is achieved by establishment of Fermi acceleration trap and parallel electrostatic potential within the flow vortex, leading to dramatic enhancement of energetic electron flux by at least 1 order of magnitude. The accelerated electrons can drive mass and energy transport along local magnetic field lines and serve as a free energy source for broadband electrostatic emissions. Our observations, suggesting that the ion flow vortex can serve as novel electron accelerators, can be fundamentally important for understanding energetic phenomena in the cosmos, such as nonthermal emissions near astrophysical jets and killer electrons in geospace.}, archive = {J_ApJ}, author = {C. M. Liu and J. B. Cao and Y. Y. Liu and E. A. Kronberg and X. N. Xing and B. N. Zhao and P. W. Daly}, doi = {10.3847/1538-4357/ada269}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {96}, shortjournal = {The Astrophys. J.}, title = {Autogenous electron acceleration by ion flow vortex in space plasmas}, volume = {979}, year = {2025}, }
• (2025). 3D localization of FRB 20190425A for its potential host galaxy and implications. ApJ, 979(2), 95. (www)

  @article{ , abstract = {Fast radio bursts (FRBs) are high-energy, short-duration phenomena in radio astronomy. Identifying their host galaxies can provide insights into their mysterious origins. In this paper, we introduce a novel approach to identifying potential host galaxies in three-dimensional space. We use FRB 20190425A and GW190425 as examples to illustrate our method. Recently, due to spatial and temporal proximity, the potential association of GW190425 with FRB 20190425A has drawn attention, leading to the identification of a likely host galaxy, UGC 10667, albeit without confirmed kilonova emissions. We search for the host galaxy of FRB 20190425A with a full CHIME localization map. Regardless of the validity of the association between GW190425 and FRB 20190425A, we identify an additional potential host galaxy (SDSS J171046.84+212732.9) from the updated GLADE galaxy catalog, supplementing the importance of exploring the new volume. We employed various methodologies to determine the most probable host galaxy of GW190424 and FRB 20190425A, including a comparison of galaxy properties and constraints on their reported observation limits using various kilonova models. Our analysis suggests that current observations do not definitively identify the true host galaxy. Additionally, the kilonova models characterized by a gradual approach to their peak are contradicted by the observational upper limits of both galaxies. Although the absence of optical emission detection raises doubts, it does not definitively disprove the connection between the gravitational wave (GW) and FRB.}, archive = {J_ApJ}, author = {Da-Chun Qiang and Zhi-Qiang You and Sheng Yang and Zong-Hong Zhu and Ting-Wan Chen}, doi = {10.3847/1538-4357/ada28c}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {95}, shortjournal = {The Astrophys. J.}, title = {3D localization of FRB 20190425A for its potential host galaxy and implications}, volume = {979}, year = {2025}, }
• (2025). Shocked POststarburst galaxy survey. IV. outflows in shocked poststarburst galaxies are not responsible for quenching. ApJ, 979(1), 94. (www)

  @article{ , abstract = {Shocked POstarburst Galaxies (SPOGs) exhibit both emission lines suggestive of shock-heated gas and poststarburst-like stellar absorption, resulting in a unique subset for galaxy evolution studies. We have observed 77 galaxies that fulfilled the SPOG criteria selection using the DeVeny Spectrograph on the Lowell Discovery Telescope. Our long-slit minor axis spectra detect H α and [O III ] in some SPOGs out to 6 kpc above the galactic plane. We find extraplanar ionized gas in 31 targets of our sample overall. Using their internal and external kinematics, we argue that 22 galaxies host outflows with ionized gas masses ranging from 10 2 M ⊙ to 10 5 M ⊙ . The rest are likely extended diffuse ionized gas. A positive correlation exists between active galactic nuclei (AGN) luminosity and the extraplanar gas extent, velocity dispersion, and mass—suggesting that the AGN may indeed drive the outflows detected in AGN hosts. The low masses of the extraplanar gas suggest that these outflows are not depleting each galaxy's gas reserves. The outflows, therefore, are not likely a significant quenching mechanism in these SPOGs.}, archive = {J_ApJ}, author = {Antoniu Fodor and Taylor Tomko and Mary Braun and Anne M. Medling and Thomas M. Johnson and Alexander Thompson and Victor D. Johnston and Matthew Newhouse and Yuanze Luo and K. Decker French and Justin A. Otter and Akshat Tripathi and Margaret E. Verrico and Katherine Alatalo and Kate Rowlands and Timothy Heckman}, doi = {10.3847/1538-4357/ad900f}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {94}, shortjournal = {The Astrophys. J.}, title = {Shocked POststarburst galaxy survey. IV. outflows in shocked poststarburst galaxies are not responsible for quenching}, volume = {979}, year = {2025}, }
• (2025). High-time-cadence spectroscopy and photometry of stellar flares on m dwarf YZ canis minoris with the seimei telescope and TESS. i. discovery of rapid and short-duration prominence eruptions. ApJ, 979(1), 93. (www)

  @article{ , abstract = {M dwarfs show frequent flares and associated coronal mass ejections (CMEs) may significantly impact close-in habitable planets. M dwarf flares sometimes show blue/red asymmetries in the H α line profile, suggesting prominence eruptions as an early stage of CMEs. However, their high-time-cadence observations are limited. We conducted spectroscopic monitoring observations of the active M dwarf YZ Canis Minoris with an ∼1 minute time cadence using the Seimei telescope, simultaneously with the optical photometric observations by Transiting Exoplanet Survey Satellite. We detected 27 H α flares with H α energies ranging from 1.7 × 10 29 to 3.8 × 10 32 erg and durations from 8 to 319 minutes. Among them, we identified three blue asymmetry and five red asymmetry events based on criteria using the Bayesian information criterion. The maximum velocity of the blueshifted and redshifted components ranges from 200 to 450 km s −1 and 190 to 400 km s −1 , respectively. The duration and time evolution show variety, and in particular, we discovered rapid, short-duration blue/red asymmetry events with the duration of 6–8 minutes. Among the eight blue/red asymmetry events, two blue and one red asymmetry events are interpreted as prominence eruptions because of their fast velocity and time evolution. Based on this interpretation, the lower limit of occurrence frequency of prominence eruptions can be estimated to be ∼1.1 events per day. Our discovery of short-duration events suggests that previous studies with low time cadence may have missed these events, potentially leading to an underestimation of the occurrence frequency of prominence eruptions/CMEs.}, archive = {J_ApJ}, author = {Yuto Kajikiya and Kosuke Namekata and Yuta Notsu and Hiroyuki Maehara and Bunei Sato and Daisaku Nogami}, doi = {10.3847/1538-4357/ad91b9}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {93}, shortjournal = {The Astrophys. J.}, title = {High-time-cadence spectroscopy and photometry of stellar flares on m dwarf YZ canis minoris with the seimei telescope and TESS. i. discovery of rapid and short-duration prominence eruptions}, volume = {979}, year = {2025}, }
• (2025). Empirical color correction to MIST and PARSEC isochrones on gaia BR − RP and g − RP with benchmark open clusters. ApJ, 979(1), 92. (www)

  @article{ , abstract = {Recent literature reports a color deviation between observed Gaia color–magnitude diagrams (CMDs) and theoretical model isochrone predictions, particularly in the very low-mass regime. To assess its impact on cluster age determination via isochrone fitting, we quantified the color deviations for three benchmark clusters, Hyades, Pleiades, and Praesepe, both for the Gaia color (BP − RP) and ( G − RP). In general, the ( G − RP) color deviations are smaller than the (BP − RP) ones. Empirical color-correction functions based on these benchmarks are derived for the currently available MESA Isochrones and Stellar Tracks and PAdova and TRieste Stellar Evolution Code (PARSEC) 1.2S isochrone models. Applying the correction functions to 31 additional open clusters and 3 moving groups results in a significantly improved alignment between the isochrones and observed CMDs. With our empirical corrections, isochrones provide age estimates consistent with literature values obtained through the spectral lithium depletion boundary method, validating the effectiveness of our approach. The corresponding metallicities with PARSEC 1.2S also show a good agreement with the spectroscopic results. The empirical color-correction function we present in this work offers a tool for a consistent age determination within the full mass range of stellar clusters using the isochrone fitting method.}, archive = {J_ApJ}, author = {Fan Wang and Min Fang and Xiaoting Fu and Yang Chen and Lu Li and Xiaoying Pang and Zhongmu Li and Jing Tang and Wenyuan Cui and Haijun Tian and Chao Liu}, doi = {10.3847/1538-4357/ad960a}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {92}, shortjournal = {The Astrophys. J.}, title = {Empirical color correction to MIST and PARSEC isochrones on gaia BR − RP and g − RP with benchmark open clusters}, volume = {979}, year = {2025}, }
• (2025). Boulder migration in the khonsu region of comet 67P/Churyumov–Gerasimenko. ApJ, 979(1), 91. (www)

  @article{ , abstract = {The European Space Agency's Rosetta mission is the only space mission that has performed long-term monitoring of a comet at close distances. For over two years, Rosetta rendezvoused with comet 67P/Churyumov–Gerasimenko, which revealed diverse evolutionary processes of the cometary nucleus. One of the most striking events is the migration of a ∼30 m boulder in the southern hemisphere region of Khonsu. Previous works found the boulder's ∼140 m displacement occurred during the three months from 2015 August to October, and several triggering mechanisms were proposed, including outburst at the boulder site, seismic vibrations from nearby activities, or surface erosion of the slope beneath the boulder. In this work, we further analyze this impressive event by analyzing imaging data from Rosetta's OSIRIS camera. We constrained the boulder's migration time to within 14 hr and derived a detailed timeline of the boulder migration event and local dust activities. High-resolution thermophysical modeling shows significant dichotomy in the thermal history of the boulder's southern and northern sides, which could have triggered or facilitated its migration via its own volatile activity.}, archive = {J_ApJ}, author = {Xiang Tang and Xian Shi and Mohamed Ramy El-Maarry}, doi = {10.3847/1538-4357/ad9825}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {91}, shortjournal = {The Astrophys. J.}, title = {Boulder migration in the khonsu region of comet 67P/Churyumov–Gerasimenko}, volume = {979}, year = {2025}, }
• (2025). A sensitivity analysis of the modeling of polycyclic aromatic hydrocarbon emission in galaxies. ApJ, 979(1), 90. (www)

  @article{ , abstract = {We have conducted a sensitivity analysis on the mid-infrared spectral decomposition of galaxies and the modeling of the polycyclic aromatic hydrocarbon (PAH) emission spectrum with the NASA Ames PAH Infrared Spectroscopic Database (PAHdb) to assess the variance on the average galaxy PAH population properties under a grid of different modeling parameters. We find that the short-low and short-low+long-low Spitzer-IRS decomposition with PAHFIT provides consistent modeling and recovery of the 5–15 μ m PAH emission spectrum. For PAHdb modeling, application of a redshift to the calculated spectra to account for anharmonic effects introduces a 15%–20% variance on the derived parameters, while its absence improves the fits by ∼13%. The 4.00- α release of PAHdb achieves the complete modeling of the 6–15 μ m PAH spectrum, including the full 6.2 μ m band, improving the average fitting uncertainty by a factor of 2. The optimal PAHdb modeling configuration requires selection of pure PAHs without applying a redshift to the bands. Although quantitatively the PAHdb-derived parameters change under different modeling configurations or database versions, their variation follows a linear scaling, with previously reported trends remaining qualitatively valid. PAHdb modeling of JWST observations, and JWST observations smoothed and resampled to the Spitzer-IRS resolution and dispersion have consistent PAHdb derived parameters. Decomposition with different codes, such as PAHFIT and CAFE, produce PAH emission spectra with noticeable variation in the 11–15 μ m region, driving a ∼7% difference in the neutral PAH fraction under PAHdb modeling. A new library of galaxy PAH emission templates is delivered to be utilized in galaxy spectral energy distribution modeling.}, archive = {J_ApJ}, author = {A. Maragkoudakis and C. Boersma and P. Temi and J. D. Bregman and L. J. Allamandola and V. J. Esposito and A. Ricca and E. Peeters}, doi = {10.3847/1538-4357/ad9918}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {90}, shortjournal = {The Astrophys. J.}, title = {A sensitivity analysis of the modeling of polycyclic aromatic hydrocarbon emission in galaxies}, volume = {979}, year = {2025}, }
• (2025). Fitting methods for probability distribution functions in turbulent star-forming clouds. ApJ, 979(1), 89. (www)

  @article{ , abstract = {We use a suite of 3D simulations of star-forming molecular clouds, with and without stellar feedback and magnetic fields, to investigate the effectiveness of different fitting methods for volume and column density probability distribution functions (PDFs). The first method fits a piecewise lognormal and power-law (PL) function to recover PDF parameters such as the PL slope and transition density. The second method fits a polynomial spline function and examines the first and second derivatives of the spline to determine the PL slope and the functional transition density. The first PL (set by the transition between lognormal and PL function) can also be visualized in the derivatives directly. In general, the two methods produce fits that agree reasonably well for volume density but vary for column density, likely due to the increased statistical noise in the column density PDFs as compared to the volume density PDFs. We test a well-known conversion for estimating volume density PL slopes from column density slopes and find that the spline method produces a better match ( χ 2 of 3.34 versus χ 2 of 5.92), albeit with a significant scatter. Ultimately, we recommend the use of both fitting methods on column density data to mitigate the effects of noise.}, archive = {J_ApJ}, author = {Avery Kiihne and Sabrina M. Appel and Blakesley Burkhart and Vadim A. Semenov and Christoph Federrath}, doi = {10.3847/1538-4357/ad99d5}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {89}, shortjournal = {The Astrophys. J.}, title = {Fitting methods for probability distribution functions in turbulent star-forming clouds}, volume = {979}, year = {2025}, }
• (2025). Persistence and burn-in in solar coronal magnetic field simulations. ApJ, 979(1), 88. (www)

  @article{ , abstract = {Simulations of solar phenomena play a vital role in space-weather prediction. A critical computational question for automating research workflows in the context of data-driven solar coronal magnetic field simulations is quantifying a simulation's burn-in time, after which a solar quantity has evolved away from an arbitrary initial condition to a physically more realistic state. A challenge to quantifying simulation burn-in is that the underlying solar processes and data, like many physical phenomena, are non-Markovian and exhibit long memory or persistence and, therefore, their analysis evades standard statistical approaches. In this work, we provide evidence of long memory in the nonperiodic variations of solar quantities (including over timescales significantly shorter than previously identified) and demonstrate that magnetofrictional simulations capture the memory structure present in magnetogram data. We also provide an algorithm for the quantitative assessment of simulation burn-in time that can be applied to nonstationary time series with long memory. Our approach is based on time-delayed mutual information, an information-theoretic quantity, and includes a small-sample bias correction.}, archive = {J_ApJ}, author = {Eric J. Hall and Karen A. Meyer and Anthony R. Yeates}, doi = {10.3847/1538-4357/ad99db}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {88}, shortjournal = {The Astrophys. J.}, title = {Persistence and burn-in in solar coronal magnetic field simulations}, volume = {979}, year = {2025}, }
• (2025). Dissecting the interstellar media of a Wolf–Rayet galaxy at z = 2.76. ApJ, 979(1), 87. (www)

  @article{ , abstract = {We report JWST/NIRSpec observations of a star-forming galaxy at z = 2.76, MACS J1149-WR1. We securely detect two temperature-sensitive auroral lines, [S iii ] 6312 (7.4 σ ) and [O ii ] 7320+7331 doublets (10 σ ), and tentatively [ n ii ] 5755 (2.3 σ ) for the first time in an individual galaxy at z > 1. We perform a detailed analysis of its interstellar media (ISM), and derive electron temperatures, various heavy element abundances (O/H, N/O, S/O, and Ar/O) in the hot ionized region, and the neutral fraction in the warm ionized region. MACS J1149-WR1 shows a broad feature at the wavelength of He ii 4686, which consists of a broad (∼1000 km s −1 ), blueshifted (∼−110 km s −1 ) line component. Taken together with its mildly elevated N/O abundance, we conclude that MACS J1149-WR1 is experiencing a young starburst (≲10 Myr), likely hosting a large number of Wolf–Rayet (W-R) stars. None of its spectral features support the presence of active galactic nuclei, including (i) the absence of broad components and velocity shifts in hydrogen recombination lines, (ii) low [Fe ii ]1.257 μ m/Pa β ratio, and (iii) the absence of high-ionization lines. Our analysis using He i lines reveals a higher electron temperature and a higher attenuation value, indicating that He i may probe a smaller spatial scale than H i , presumably the region dominated by the aforementioned W-R stars. The star formation rates derived from various He i lines broadly agree with those from hydrogen recombination lines. We thus advocate that He i can be an excellent, independent probe of multiphase ISM in the era of JWST.}, archive = {J_ApJ}, author = {Takahiro Morishita and Massimo Stiavelli and Stefan Schuldt and Claudio Grillo}, doi = {10.3847/1538-4357/ad9aa2}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {87}, shortjournal = {The Astrophys. J.}, title = {Dissecting the interstellar media of a Wolf–Rayet galaxy at z = 2.76}, volume = {979}, year = {2025}, }
• (2025). A peculiar feature of the first ionization potential effect before a solar flare impulsive phase observed by MSS-1B, CHASE, and SDO. ApJ, 979(1), 86. (www)

  @article{ , abstract = {The impulsive phase of solar flares is often accompanied by the depletion of the elements with low first ionization potential (FIP), whose abundance decreases from the coronal level to the photospheric level, and then recovers back to the coronal level during the decay phase. Recently, we analyzed the soft X-ray spectroscopic data of the 2024 February 16 flare event observed by the Macao Science Satellite-1B/Soft X-ray Detection Units. Surprisingly, however, it is revealed that the depletion of the low-FIP elements occurred well before the flare impulsive phase. The timing of this change provides important clues about the location of magnetic reconnection, shedding light on the mass and energy transfer between different layers of the solar atmosphere. By examining the multiwavelength data from the Solar Dynamics Observatory and CHASE missions, we found that there was no filament 0.4 hr before the flare eruption. However, an erupting filament was detected in association with the flare event. Based on these features, we propose for the first time that the flare/filament eruption for this event was initiated by magnetic reconnection in the solar chromosphere, rather than in the corona as stated in the standard flare model.}, archive = {J_ApJ}, author = {Man-Hei Ng and Xiaoping Zhang and P. F. Chen}, doi = {10.3847/1538-4357/ad9b0a}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {86}, shortjournal = {The Astrophys. J.}, title = {A peculiar feature of the first ionization potential effect before a solar flare impulsive phase observed by MSS-1B, CHASE, and SDO}, volume = {979}, year = {2025}, }
• (2025). Dependence of metal enrichment of nuclear star clusters on galaxy stellar mass. ApJ, 979(1), 85. (www)

  @article{ , abstract = {Nuclear star clusters (NSCs) are commonly found in the centers of galaxies, but their dominant formation mechanisms remain elusive. We perform a consistent analysis of stellar populations of 97 nearby NSCs, based on spectroscopic data from the Very Large Telescope. The sample covers a galaxy stellar mass range of 10 7 –10 11 M ⊙ and is more than 3 times larger than any previous study. We identify three galaxy stellar mass regimes with distinct NSC properties. In the low-mass regime of \mathrm{log}{M}_{{\rm{host}}} ≲ 8.5 ( M host is in units of M ⊙ ), nearly all NSCs have metallicities lower than their circum-NSC host but similar to those of typical red globular clusters (GCs), supporting the GC inspiral–merger scenario of NSC formation. In the high-mass regime of \mathrm{log}{M}_{{\rm{host}}} ≳ 9.5, nearly all NSCs have higher metallicities than their circum-NSC host and red GCs, suggesting significant contributions from in situ star formation. In the intermediate-mass regime, a comparable fraction of NSCs have higher or lower metallicities than their circum-NSC host and red GCs, with no clear dependence on NSC mass, suggesting intermittent in situ star formation. The majority of NSCs with higher metallicities than their host exhibit a negative age–metallicity correlation, providing clear evidence of long-term chemical enrichment. The average metallicity difference between NSC and host peaks broadly around \mathrm{log}{M}_{{\rm{host}}}\sim 9.8 and declines toward both higher and lower galaxy masses. We find that the efficiency of dynamical-friction-driven inspiral of GCs observed in present-day galaxies can explain the NSC mass at \mathrm{log}{M}_{{\rm{host}}}\lesssim 9.5 but falls short of observed ones at higher galaxy mass, reinforcing our conclusions based on stellar population analysis.}, archive = {J_ApJ}, author = {Wenhe Lyu and Hong-Xin Zhang and Sanjaya Paudel and Tie Li and Yimeng Tang and Guangwen Chen and Xu Kong and Eric W. Peng}, doi = {10.3847/1538-4357/ad9b0d}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {85}, shortjournal = {The Astrophys. J.}, title = {Dependence of metal enrichment of nuclear star clusters on galaxy stellar mass}, volume = {979}, year = {2025}, }
• (2025). Evolution of magnetic reconnection in an electron-scale current sheet. ApJ, 979(1), 84. (www)

  @article{ , abstract = {Recently, a new type of magnetic reconnection, electron-only reconnection—where there is no obvious ion flow and heating—has been observed in various plasma environments. Previous kinetic simulations have shown that electron-only reconnection is a precursor of standard reconnection. In this paper, by performing a 2.5-dimensional particle-in-cell simulation, we investigate the evolution of electron-only magnetic reconnection to standard magnetic reconnection in a current sheet, whose initial width is of the electron inertial length. In the electron-only reconnection stage, electron outflow produces the electron-scale {B}_{z} pileup, and ions are slightly accelerated in the outflow direction by the Hall electric field force. As the reconnection electric field expands and {B}_{z} is piled up to the ion scale, ions start to be further accelerated inside the ion diffusion region and reflected by the {B}_{z} to the outflow direction. With {B}_{z} pileup as the bond, ions gradually transit from being accelerated by the Hall electric field to being coupled in reconnection by the Lorentz force.}, archive = {J_ApJ}, author = {Yundan Guan and Quanming Lu and San Lu and Rongsheng Wang}, doi = {10.3847/1538-4357/ad9b15}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {84}, shortjournal = {The Astrophys. J.}, title = {Evolution of magnetic reconnection in an electron-scale current sheet}, volume = {979}, year = {2025}, }
• (2025). Geometrical distances of extragalactic binaries through spectroastrometry. ApJ, 979(1), 83. (www)

  @article{ , abstract = {The growing "Hubble tension" has prompted the need for precise measurements of cosmological distances. This paper demonstrates a purely geometric approach for determining the distances to extragalactic binaries through a joint analysis of spectroastrometry (SA), radial velocity (RV), and light-curve (LC) observations. A parameterized model for the binary system is outlined, and simulated SA, RV, and LC data are computed to infer the probability distribution of model parameters based on the mock data. The impacts of data quality and binary parameters on the distance uncertainties are comprehensively analyzed, showcasing the method's potential for high-precision distance measurements. For a typical eclipsing binary in the Large Magellanic Cloud, the distance uncertainty is approximately 6% under reasonable observational conditions. Within a specific range of data quality and input parameters, the distance measurement precision of individual binary star systems is generally better than 10%. As a geometric method based on the simplest dynamics, it is independent of empirical calibration, and the systematics caused by model selections can be tested using nearby binaries with known distances. By measuring multiple binary star systems or monitoring one binary system repeatedly, geometric distance measurements of nearby galaxies can be achieved, providing valuable insights into the Hubble tension and advancing our understanding of the Universe's structure and evolution.}, archive = {J_ApJ}, author = {Yu-Yang Songsheng and Jian-Min Wang and Yuan Cao and XueFei Chen and JianPing Xiong and Zhi-Xiang Zhang and Rong-Gen Cai}, doi = {10.3847/1538-4357/ad9d10}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {83}, shortjournal = {The Astrophys. J.}, title = {Geometrical distances of extragalactic binaries through spectroastrometry}, volume = {979}, year = {2025}, }
• (2025). Detecting the black hole candidate population in m51’s young massive star clusters: Constraints on accreting intermediate-mass black holes. ApJ, 979(1), 82. (www)

  @article{ , abstract = {Intermediate-mass black holes (10 2 < M BH < 10 5 M ⊙ ) are an open question in our understanding of black hole evolution and growth. They have long been linked to dense star cluster environments, thanks to cluster dynamics, but there are a limited number of secure detections. We leverage existing X-ray observations from the Chandra X-ray Observatory and optical catalogs from the Hubble Space Telescope (HST) as well as new radio observations from the Karl G. Jansky Very Large Array to search for any evidence of accreting black holes in young massive star clusters in the nearby galaxy M51. We find that of 44 bright ( L X > 10 38 erg s −1 ) X-ray point sources in M51, 24 had probable matches to objects including possible associated star clusters in the HST Legacy Extragalactic UV Survey catalog, seven of which were classified as contaminants (background galaxies or foreground stars). We explore the optical properties of the remaining 17 sources, including cluster age and mass estimates, and search for radio counterparts in the 8–12 GHz band. The lack of radio counterparts to X-ray sources we know to be associated with young massive star clusters in M51 suggests that we do not significantly detect hard-state intermediate-mass black holes (IMBHs)  ~10 4 M ⊙ or above. However, more sensitive radio facilities, like the Square Kilometre Array and next-generation Very Large Array, may be able to provide evidence for IMBHs with masses down to  ~10 3 M ⊙ .}, archive = {J_ApJ}, author = {Kristen C. Dage and Evangelia Tremou and Bolivia Cuevas Otahola and Eric W. Koch and Kwangmin Oh and Richard M. Plotkin and Vivian L. Tang and Muhammad Ridha Aldhalemi and Zainab Bustani and Mariam Ismail Fawaz and Hans J. Harff and Amna Khalyleh and Timothy McBride and Jesse Mason and Anthony Preston and Cortney Rinehart and Ethan Vinson and Gemma Anderson and Edward M. Cackett and Shih Ching Fu and Sebastian Kamann and Teresa Panurach and Renuka Pechetti and Payaswini Saikia and Susmita Sett and Ryan Urquhart and Christopher Usher}, doi = {10.3847/1538-4357/ad9d37}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {82}, shortjournal = {The Astrophys. J.}, title = {Detecting the black hole candidate population in m51’s young massive star clusters: Constraints on accreting intermediate-mass black holes}, volume = {979}, year = {2025}, }
• (2025). Exploring the circumstellar environment of tycho’s supernova remnant. II. impact on the broadband nonthermal emission. ApJ, 979(1), 81. (www)

  @article{ , abstract = {While the environment around Tycho's supernova remnant has long been believed to be close to homogeneous, the latest analysis of Chandra data has identified a substantial deceleration of the forward shock, which poses a major challenge to this picture. R. Kobashi et al. showed that the existence of dense molecular cloud (MC) surrounding a rarefied wind-like circumstellar matter (CSM) can explain this observational finding in terms of the shock-expansion dynamics, supporting the so-called single-degenerate scenario for the progenitor system. We here extend this work to study the nonthermal emission processes and investigate whether such an environment is consistent with the observed multiwavelength spectrum. While the simulated broadband spectrum based on the wind–MC environment is largely consistent with observations, we find that such an environment predicts a harder gamma-ray spectrum than observed due to the relatively low CSM density in the cavity interior of the MC. This difference can be at least partially attributed to the present 1D setup of the model, which does not account for the clumpy and multidimensional structure of the CSM. Our model provides predictions for the long-term evolution of the broadband spectrum, which can be used to further probe Tycho's surrounding environment in the future, a key to resolving the long-standing issue of Type Ia supernova progenitor channels.}, archive = {J_ApJ}, author = {Ryosuke Kobashi and Shiu-Hang Lee and Takaaki Tanaka and Keiichi Maeda}, doi = {10.3847/1538-4357/ad9d3b}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {81}, shortjournal = {The Astrophys. J.}, title = {Exploring the circumstellar environment of tycho’s supernova remnant. II. impact on the broadband nonthermal emission}, volume = {979}, year = {2025}, }
• (2025). Tidally distorted stars are triaxial pulsators. ApJ, 979(1), 80. (www)

  @article{ , abstract = {Stars in close binaries are tidally distorted, and this has a strong effect on their pulsation modes. We compute the mode frequencies and geometries of tidally distorted stars using perturbation theory, accounting for the effects of the Coriolis force and the coupling between different azimuthal orders m of a multiplet induced by the tidal distortion. For tidally coupled dipole pressure modes, the tidal coupling dominates over the Coriolis force and the resulting pulsations are "triaxial," with each of the three modes in a multiplet "tidally tilted," to be aligned with one of the three principal axes of the star. The observed amplitudes and phases of the dipole modes aligned orthogonal to the spin axis are modulated throughout the orbit, producing doublets in the power spectrum that are spaced by exactly twice the orbital frequency. Quadrupole modes have similar but slightly more complex behavior. This amplitude modulation allows for mode identification, which can potentially enable detailed asteroseismic analyses of tidally tilted pulsators. Pressure modes should exhibit this behavior in stellar binaries close enough to be tidally synchronized, while gravity modes should remain aligned with the star's spin axis. We discuss applications to various types of pulsating stars and the relationship between the tidal tilting of pulsations and the "single-sided" pulsations sometimes observed in very tidally distorted stars.}, archive = {J_ApJ}, author = {Jim Fuller and Saul Rappaport and Rahul Jayaraman and Don Kurtz and Gerald Handler}, doi = {10.3847/1538-4357/ad9eb2}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {80}, shortjournal = {The Astrophys. J.}, title = {Tidally distorted stars are triaxial pulsators}, volume = {979}, year = {2025}, }
• (2025). Most super-earths have less than 3% water. ApJ, 979(1), 79. (www)

  @article{ , abstract = {Super-Earths are highly irradiated, small planets with bulk densities approximately consistent with Earth. We construct combined interior atmosphere models of super-Earths that trace the partitioning of water throughout a planet, including an iron-rich core, silicate-rich mantle, and steam atmosphere. We compare these models with exoplanet observations to infer a 1 σ upper limit on the total water mass fraction of ≲3% at the population level. We consider end-member scenarios that may change this value, including the efficiency of mantle outgassing, escape of high mean molecular weight atmospheres, and increased iron core mass fractions. Although our constraints are agnostic as to the origin of water, we show that our upper limits are consistent with its production via chemical reactions of primordial hydrogen-dominated atmospheres with magma oceans. This mechanism has also been hypothesised to explain Earth's water content, possibly pointing to a unified channel for the origins of water on small terrestrial planets.}, archive = {J_ApJ}, author = {James G. Rogers and Caroline Dorn and Vivasvaan Aditya Raj and Hilke E. Schlichting and Edward D. Young}, doi = {10.3847/1538-4357/ad9f61}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {79}, shortjournal = {The Astrophys. J.}, title = {Most super-earths have less than 3% water}, volume = {979}, year = {2025}, }
• (2025). An effect study of structural jets on the long gamma-ray burst formation rate at low redshift. ApJ, 979(1), 78. (www)

  @article{ , abstract = {Gamma-ray bursts (GRBs) are considered the most violent explosions in the Universe. Numerous studies have analyzed the formation rate of long gamma-ray bursts (LGRBs), which originate from the core collapse of massive stars, in comparison with the star formation rate (SFR). It is found that the LGRB formation rate at redshift z < 1 is significantly distinct from the SFR and is higher. Moreover, due to the threshold of detectors, the structured jets of GRBs also affect detection numbers at different redshifts, which all influence the calculation of the formation rate. Thus we investigate the LGRB formation rate at low redshift and further explore the possible correlation between the LGRB formation rate under the influence of structural jets and the SFR. We use Lynden-Bell's c − method to study the luminosity function and rate of Swift LGRBs without any assumptions. After correcting for the redshift evolution, the luminosity function can be expressed as \psi ({L}_{0})\propto {L}_{0}^{-0.17\pm 0.01} for dim LGRBs and \psi ({L}_{0})\propto {L}_{0}^{-1.36\pm 0.05} for bright LGRBs, and the formation rate at z < 1 shows an increase. Then we use Monte Carlo simulations to create pseudo-GRBs with structured jets and calculate the formation rates assuming that the actual LGRB formation rate at low redshift is proportional to the SRF. The results demonstrate that structural jets increase the number of detections at low redshift in response to observational effects. Compared with the observed formation rate, the structured jet model with Gauss-cocoon is found to be relatively more efficient, and the parameters η of this model are limited and analyzed to [0.5, 5].}, archive = {J_ApJ}, author = {Qi Guo and Qi Tan and Benyun Shi}, doi = {10.3847/1538-4357/ada14d}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {78}, shortjournal = {The Astrophys. J.}, title = {An effect study of structural jets on the long gamma-ray burst formation rate at low redshift}, volume = {979}, year = {2025}, }
• (2025). Foreshock ultralow frequency waves at mars: Consequence on the particle acceleration mechanisms at the martian bow shock. ApJ, 979(1), 77. (www)

  @article{ , abstract = {Using Mars Atmosphere and Volatile EvolutioN Magnetometer observations, we report the first statistical study of ultralow frequency (ULF) waves at the Martian foreshock. The analyzed foreshock ULF wave events are observed in the 0.008–0.086 Hz frequency range, with nearly circular and elliptical left-handed polarization in the spacecraft reference frame. These waves are propagated quasi-parallel to the ambient magnetic field, with a moderate wave amplitude. All these properties are consistent with fast magnetosonic waves, most likely generated through the ion–ion right-hand resonant instability. In addition, our results suggest that the associated resonant backstreaming protons' velocities parallel to the mean magnetic field in the solar wind reference frame are 1.33 ± 0.40 times the solar wind velocity. The similarity between our results and previous reports at other foreshocks may indicate the presence of a common acceleration process acting in planetary bow shocks and that is responsible for this particular backstreaming population.}, archive = {J_ApJ}, author = {Nahuel Andrés and Norberto Romanelli and Christian Mazelle and Li-Jen Chen and Jacob R. Gruesbeck and Jared R. Espley}, doi = {10.3847/1538-4357/ada250}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {77}, shortjournal = {The Astrophys. J.}, title = {Foreshock ultralow frequency waves at mars: Consequence on the particle acceleration mechanisms at the martian bow shock}, volume = {979}, year = {2025}, }
• (2025). A magnetohydrodynamics simulation of coronal mass ejections in the upper corona at 2.5R⊙ ≤ r ≤ 19R⊙. ApJ, 979(1), 76. (www)

  @article{ , abstract = {The methodology of a new magnetohydrodynamics simulation model of the propagation of coronal mass ejections (CMEs) in the near-Sun solar wind region at 2.5 R ⊙ ≥ r ≥ 19 R ⊙ is presented. The simulation model first determines the steady state of the transonic/Alfvénic solar wind with the characteristic-based inner boundary treatment for the middle of the corona at r = 2.5 R ⊙ (K. Hayashi et al. 2023 ). To determine the numerical perturbation on the 2.5 R ⊙ inner boundary surface, a kinetic self-similar model with a torus-shaped magnetic-field rope and a spherically symmetric plasma structure translating and expanding at the constant speed (named TICK model) is developed. A solar-wind MHD model (C.-C. Wu et al. 2020b ) traces the temporal evolution of the injected CME through the inner boundary surface. We conducted test simulations with various choices of plasma density and temperature. The test simulation results show that the injected CME, particularly its internal magnetic structure, can be substantially altered through the interactions with the preexisting slow and dense ambient solar wind at the early phase of the propagation in the near-Sun region. The propagation speed of the discontinuity front is found to be dependent on the plasma parameters of the CME perturbation. Therefore, for better simulating the propagation of the CME, it is important for the CME models to include the nonlinear MHD interactions in the subsonic/Alfvénic regions.}, archive = {J_ApJ}, author = {Keiji Hayashi and Chin-Chun Wu and Kan Liou}, doi = {10.3847/1538-4357/ada282}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {76}, shortjournal = {The Astrophys. J.}, title = {A magnetohydrodynamics simulation of coronal mass ejections in the upper corona at 2.5R⊙ ≤ r ≤ 19R⊙}, volume = {979}, year = {2025}, }
• (2025). The multiple extended tidal tails of NGC 288. ApJ, 979(1), 75. (www)

  @article{ , abstract = {Using photometry and proper motions from Pan-STARRS, DECaLS, and Gaia Data Release 3, we detect a ∼35°–70° long trailing stellar debris stream associated with the globular cluster NGC 288. The trajectory of the trailing tail is not well matched by a model stream evolved in a static Galactic potential, but is reasonably well matched by a stream modeled in a potential that incorporates a massive, infalling Large Magellanic Cloud. We also detect a broad, at least ∼40° long leading tail that appears to be composed of at least two narrower, spatially offset, and kinematically distinct streams. Stream modeling predicts a similar broad composite of streams and suggests that these narrower components could each be made up of one or more generations of tidal tails, each formed during different orbits over the past few gigayears. On the other hand, NGC 288 is believed to have been brought into the Galactic halo during the Gaia–Enceladus–Sausage accretion event, and the tangential velocity dispersions of our stream candidates are indeed mostly consistent with having been stripped in a parent galaxy that had a large, cored dark matter halo. Tables of the most highly ranked stream star candidates are provided for ongoing and future spectroscopic surveys.}, archive = {J_ApJ}, author = {Carl J. Grillmair}, doi = {10.3847/1538-4357/ada2ea}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {75}, shortjournal = {The Astrophys. J.}, title = {The multiple extended tidal tails of NGC 288}, volume = {979}, year = {2025}, }
• (2025). Early enrichment population theory at high redshift. ApJ, 979(1), 74. (www)

  @article{ , abstract = {An early enrichment population (EEP) has been theorized to produce the observed intracluster medium (ICM) metallicity of galaxy clusters. This population likely existed at high redshifts ( z ∼ 10), relics of which we posit exist today as dwarf galaxies. Previous work has argued that the initial mass function (IMF) of the EEP must be flatter than those found at lower redshifts, but with considerable uncertainties. In this work, we present a more quantitative model for the EEP and demonstrate how observational constraints can be applied to the IMF using supernova Type Ia (SN Ia) rates, delay time distributions (DTDs), and the luminosity functions (LFs) of galaxy clusters. We determine best-fit values for the slope and mass break of the IMF by comparing IMFs from literature with observed DTDs and the low-luminosity component ( M ( R ) > −12) of the Coma LF. We derive two best-fit IMFs, flatter than standard IMFs: (1) α lo = −0.13 ± 0.24 for 0.07 < M / M ⊙ < 1.75 and α hi = 0.53 ± 0.01 for 1.75 < M / M ⊙ < 150; and (2) α lo = 1.06 ± 0.11 for 0.07 < M / M ⊙ < 6 and α hi = 0.53 ± 0.01 for 6 < M / M ⊙ < 150. We compare these with sl-5 from M. Loewenstein (2013), with α = 0.5 for 0.07 < M / M ⊙ < 8 and α = 0.3 for 8 < M / M ⊙ < 150. This EEP model, along with stars formed at later times, can produce the observed ICM metallicity, is consistent with observations, and predicts a significant rise in the SN Ia rate at increasing redshift.}, archive = {J_ApJ}, author = {Anne E. Blackwell and Joel N. Bregman}, doi = {10.3847/1538-4357/ad9826}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {74}, shortjournal = {The Astrophys. J.}, title = {Early enrichment population theory at high redshift}, volume = {979}, year = {2025}, }
• (2025). A subclass of gamma-ray burst originating from compact binary merger. ApJ, 979(1), 73. (www)

  @article{ , abstract = {Type I gamma-ray bursts (GRBs) are believed to originate from compact binary mergers usually with a duration of main emission less than 2 s. However, recent observations of GRB 211211A and GRB 230307A indicate that some merger-origin GRBs could last much longer. Since they show strikingly similar properties (indicating a common mechanism), which are different from the classic "long"-short burst (e.g., GRB 060614), we find they form an interesting subclass of type I GRBs, and we suggest to name them as type IL GRB. We find that the prompt emission of type IL GRB is composed of three episodes: (1) a precursor followed by a short quiescent (or weak emission) period, (2) a long-duration main emission, and (3) an extended emission. With this burst pattern, a good candidate, GRB 170228A, was found in the Fermi/Gamma-ray Burst Monitor archive data. Temporal and spectral analyses indeed show that GRB 170228A falls in the same group with GRB 211211A and GRB 230307A in many diagnostic figures. Thus, this burst pattern could be a good reference for rapidly identifying type IL GRBs and very helpful for conducting low-latency follow-up observation. We estimated the occurrence rate and discussed the physical origins and implications for the three emission episodes of type IL GRBs. Our analysis suggests the premerger precursor model, especially the magnetar super flare model, is more favored for type IL GRBs. More observations in multiwavelength and multimessenger are required to deepen our understanding of this subclass of GRB.}, archive = {J_ApJ}, author = {Chen-Wei Wang and Wen-Jun Tan and Shao-Lin Xiong and Shu-Xu Yi and Rahim Moradi and Bing Li and Zhen Zhang and Yu Wang and Yan-Zhi Meng and Bo-Bing Wu and Jia-Cong Liu and Yue Wang and Sheng-Lun Xie and Wang-Chen Xue and Zheng-Hang Yu and Peng Zhang and Wen-Long Zhang and Yan-Qiu Zhang and Chao Zheng}, doi = {10.3847/1538-4357/ad98ec}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {73}, shortjournal = {The Astrophys. J.}, title = {A subclass of gamma-ray burst originating from compact binary merger}, volume = {979}, year = {2025}, }
• (2025). Spectrum and location of ongoing extreme particle acceleration in cassiopeia a. ApJ, 979(1), 72. (www)

  @article{ , abstract = {Young supernova remnants (SNRs) are believed to be the origin of energetic cosmic rays (CRs) below the "knee" of their spectrum at ∼3 PeV (10 15 eV). Nevertheless, the precise location, duration, and operation of CR acceleration in young SNRs are open questions. Here, we report on multiepoch X-ray observations of Cassiopeia A (Cas A), a 350 yr old SNR, in the 15–50 keV band that probes the most energetic CR electrons. The observed X-ray flux decrease (15% ± 1% over 10 yr), contrary to the expected >90% decrease based on previous radio, X-ray, and gamma-ray observations, provides unambiguous evidence for CR electron acceleration operating in Cas A. A temporal model for the radio and X-ray data accounting for electron cooling and continuous injection finds that the freshly injected electron spectrum is significantly harder (exponential cutoff power-law index q = 2.15), and its cutoff energy is much higher ( E cut = 36 TeV), than the relic electron spectrum ( q = 2.44 ± 0.03, E cut = 4 ± 1 TeV). Both electron spectra are naturally explained by the recently developed modified nonlinear diffusive shock acceleration (mNLDSA) mechanism. The CR protons producing the observed gamma rays are likely accelerated at the same location by the same mechanism as the injected electrons. The Cas A observations and spectral modeling represent the first time radio, X-ray, gamma-ray, and CR spectra have been self-consistently tied to a specific acceleration mechanism—mNLDSA—in a young SNR.}, archive = {J_ApJ}, author = {Jooyun Woo and Kaya Mori and Charles J. Hailey and Elizabeth Spira-Savett and Aya Bamba and Brian W. Grefenstette and Thomas B. Humensky and Reshmi Mukherjee and Samar Safi-Harb and Tea Temim and Naomi Tsuji}, doi = {10.3847/1538-4357/ad98f1}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {72}, shortjournal = {The Astrophys. J.}, title = {Spectrum and location of ongoing extreme particle acceleration in cassiopeia a}, volume = {979}, year = {2025}, }
• (2025). Unveiling the dark side of Ultraviolet/Optical bright galaxies: Optically thick dust absorption. ApJ, 979(1), 71. (www)

  @article{ , abstract = {Over the past decades, a population of galaxies invisible in optical/near-infrared (NIR), but bright at longer wavelengths, have been identified through color selections. These so-called optically faint/dark galaxies are considered to be massive quiescent galaxies or highly dust-attenuated galaxies. Having the entire galaxy obscured by dust, however, is likely an extreme case of the much more common occurrence of optically thin and thick absorption coexisting in the same system. With the power of JWST imaging, we are able to spatially resolve massive galaxies at z ∼ 3, accurately model their spectral energy distributions, and identify candidate optically thick substructures. We target galaxies with \mathrm{log}({M}_{* }/{M}_{\odot })\gt 10.3 and 2.5 < z < 3.5, and get 486 galaxies in Cosmic Evolution Early Release Science Survey and Public Release Imaging for Extragalactic Research fields. Based on excess NIR luminosity, we identify 162 galaxies (∼33% of the parent sample) as candidate hosts of optically thick substructures. We then carry out spatially resolved spectral energy distribution modeling to explore the physical properties of those dark substructures and estimate the amount of optically thick obscuration. We find that optically thick dust is ubiquitous in normal massive galaxies with a wide variety of star formation rate (SFR) and morphology. 10%–20% of the stellar mass/SFR are unaccounted for in our selected galaxies, and the fraction is insensitive to stellar mass or SFR. The dark substructures are generally dustier than the rest of the galaxies and are irregularly distributed, arguing against an obscured active galactic nucleus as the source of the NIR excess. A correlation between the obscured luminosity and the presence of a recent starburst in the past  ≲100 Myr is also observed.}, archive = {J_ApJ}, author = {Yingjie Cheng and Mauro Giavalisco and Bren E. Backhaus and Rachana Bhatawdekar and Nikko J. Cleri and Luca Costantin and Emanuele Daddi and Mark Dickinson and Steven L. Finkelstein and Michaela Hirschmann and Benne W. Holwerda and Anton M. Koekemoer and Ray A. Lucas and Fabio Pacucci and Pablo G. Pérez-González and Giulia Rodighiero and Lise-Marie Seillé and Katherine E. Whitaker and L. Y. Aaron Yung and Pablo Arrabal Haro and Micaela B. Bagley and Jeyhan S. Kartaltepe and Casey Papovich and Nor Pirzkal}, doi = {10.3847/1538-4357/ad9909}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {71}, shortjournal = {The Astrophys. J.}, title = {Unveiling the dark side of Ultraviolet/Optical bright galaxies: Optically thick dust absorption}, volume = {979}, year = {2025}, }
• (2025). An enigmatic PeVatron in an area around h ii region g35.6−0.5. ApJ, 979(1), 70. (www)

  @article{ , abstract = {Identifying Galactic PeVatrons (PeV particle accelerators) from ultrahigh-energy (UHE, >100 TeV) γ -ray sources plays a crucial role in revealing the origin of Galactic cosmic rays. The UHE source 1LHAASO J1857+0203u is suggested to be associated with HESS J1858+020, which may be attributed to the possible PeVatron candidate supernova remnant (SNR) G35.6−0.4 or H ii region G35.6−0.5. We perform detailed analysis on the very-high-energy and UHE γ -ray emissions toward this region with data from the Large High Altitude Air Shower Observatory (LHAASO). 1LHAASO J1857+0203u is detected with a significance of 11.6 σ above 100 TeV, indicating the presence of a PeVatron. It has an extent of ∼0 \mathop{.}\limits^{\unicode{x000B0}} 18 with a power-law (PL) spectral index of ∼2.5 at 1–25 TeV and pointlike emission with a PL spectral index of ∼3.2 above 25 TeV. Using archival CO and H i data, we identify some molecular and atomic clouds that may be associated with the TeV γ -ray emissions. Our modeling indicates that the TeV γ -ray emissions are unlikely to arise from clouds illuminated by the protons that escaped from SNR G35.6−0.4. In the scenario in which H ii region G35.6−0.5 could accelerate particles to the UHE band, the observed GeV–TeV γ -ray emission could be well explained by a hadronic model with a PL spectral index of ∼2.0 and cutoff energy of ∼450 TeV. However, an origin in an evolved pulsar wind nebula cannot be ruled out.}, archive = {J_ApJ}, author = {Zhen Cao and F. Aharonian and Axikegu and Y. X. Bai and Y. W. Bao and D. Bastieri and X. J. Bi and Y. J. Bi and W. Bian and A. V. Bukevich and Q. Cao and W. Y. Cao and Zhe Cao and J. Chang and J. F. Chang and A. M. Chen and B. Q. Chen and E. S. Chen and H. X. Chen and Liang Chen and Lin Chen and Long Chen and M. J. Chen and M. L. Chen and Q. H. Chen and S. Chen and S. H. Chen and S. Z. Chen and T. L. Chen and Y. Chen and N. Cheng and Y. D. Cheng and M. C. Chu and M. Y. Cui and S. W. Cui and X. H. Cui and Y. D. Cui and B. Z. Dai and H. L. Dai and Z. G. Dai and Danzengluobu and X. Q. Dong and K. K. Duan and J. H. Fan and Y. Z. Fan and J. Fang and J. H. Fang and K. Fang and C. F. Feng and H. Feng and L. Feng and S. H. Feng and X. T. Feng and Y. Feng and Y. L. Feng and S. Gabici and B. Gao and C. D. Gao and Q. Gao and W. Gao and W. K. Gao and M. M. Ge and T. T. Ge and L. S. Geng and G. Giacinti and G. H. Gong and Q. B. Gou and M. H. Gu and F. L. Guo and J. Guo and X. L. Guo and Y. Q. Guo and Y. Y. Guo and Y. A. Han and O. A. Hannuksela and M. Hasan and H. H. He and H. N. He and J. Y. He and Y. He and Y. K. Hor and B. W. Hou and C. Hou and X. Hou and H. B. Hu and Q. Hu and S. C. Hu and C. Huang and D. H. Huang and T. Q. Huang and W. J. Huang and X. T. Huang and X. Y. Huang and Y. Huang and Y. Y. Huang and X. L. Ji and H. Y. Jia and K. Jia and H. B. Jiang and K. Jiang and X. W. Jiang and Z. J. Jiang and M. Jin and M. M. Kang and I. Karpikov and D. Khangulyan and D. Kuleshov and K. Kurinov and B. B. Li and C. M. Li and Cheng Li and Cong Li and D. Li and F. Li and H. B. Li and H. C. Li and Jian Li and Jie Li and K. Li and S. D. Li and W. L. Li and X. R. Li and Xin Li and Y. Z. Li and Zhe Li and Zhuo Li and E. W. Liang and Y. F. Liang and S. J. Lin and B. Liu and C. Liu and D. Liu and D. B. Liu and H. Liu and H. D. Liu and J. Liu and J. L. Liu and M. Y. Liu and R. Y. Liu and S.M. Liu and W. Liu and Y. Liu and Y. N. Liu and Q. Luo and Y. Luo and H. K. Lv and B. Q. Ma and L. L. Ma and X. H. Ma and J. R. Mao and Z. Min and W. Mitthumsiri and H. J. Mu and Y. C. Nan and A. Neronov and K. C. Y. Ng and L. J. Ou and P. Pattarakijwanich and Z. Y. Pei and J. C. Qi and M. Y. Qi and B. Q. Qiao and J. J. Qin and A. Raza and D. Ruffolo and A. Sáiz and M. Saeed and D. Semikoz and L. Shao and O. Shchegolev and X. D. Sheng and F. W. Shu and H. C. Song and Yu. V. Stenkin and V. Stepanov and Y. Su and D. X. Sun and Q. N. Sun and X. N. Sun and Z. B. Sun and J. Takata and P. H. T. Tam and Q. W. Tang and R. Tang and Z. B. Tang and W. W. Tian and L. H. Wan and C. Wang and C. B. Wang and G. W. Wang and H. G. Wang and H. H. Wang and J. C. Wang and Kai Wang and L. P. Wang and L. Y. Wang and P. H. Wang and R. Wang and W. Wang and X. G. Wang and X. Y. Wang and Y. Wang and Y. D. Wang and Y. J. Wang and Z. H. Wang and Z. X. Wang and Zhen Wang and Zheng Wang and D. M. Wei and J. J. Wei and Y. J. Wei and T. Wen and C. Y. Wu and H. R. Wu and Q. W. Wu and S. Wu and X. F. Wu and Y. S. Wu and S. Q. Xi and J. Xia and G. M. Xiang and D. X. Xiao and G. Xiao and Y. L. Xin and Y. Xing and D. R. Xiong and Z. Xiong and D. L. Xu and R. F. Xu and R. X. Xu and W. L. Xu and L. Xue and D. H. Yan and J. Z. Yan and T. Yan and C. W. Yang and C. Y. Yang and F. Yang and F. F. Yang and L. L. Yang and M. J. Yang and R. Z. Yang and W. X. Yang and Y. H. Yao and Z. G. Yao and L. Q. Yin and N. Yin and X. H. You and Z. Y. You and Y. H. Yu and Q. Yuan and H. Yue and H. D. Zeng and T. X. Zeng and W. Zeng and M. Zha and B. B. Zhang and F. Zhang and H. Zhang and H. M. Zhang and H. Y. Zhang and J. L. Zhang and Li Zhang and P. F. Zhang and P. P. Zhang and R. Zhang and S. B. Zhang and S. R. Zhang and S. S. Zhang and X. Zhang and X. P. Zhang and Y. F. Zhang and Yi Zhang and Yong Zhang and B. Zhao and J. Zhao and L. Zhao and L. Z. Zhao and S. P. Zhao and X. H. Zhao and F. Zheng and W. J. Zhong and B. Zhou and H. Zhou and J. N. Zhou and M. Zhou and P. Zhou and R. Zhou and X. X. Zhou and B. Y. Zhu and C. G. Zhu and F. R. Zhu and H. Zhu and K. J. Zhu and Y. C. Zou and X. Zuo and (The LHAASO Collaboration)}, doi = {10.3847/1538-4357/ad991d}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {70}, shortjournal = {The Astrophys. J.}, title = {An enigmatic PeVatron in an area around h ii region g35.6−0.5}, volume = {979}, year = {2025}, }
• (2025). Search for and analysis of eclipsing binaries in the LAMOST medium-resolution survey field. i. R.A.: 23h01m51s, decl.: +34°36′45″. ApJ, 979(1), 69. (www)

  @article{ , abstract = {Eclipsing binaries (EBs) play an important astrophysical role in studying stellar properties and evolution. By analyzing photometric data in the the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) Medium-Resolution Survey field, R.A.: 23 h 01 m 51 \mathop{.}\limits^{{\rm{s}}} 00, decl.: +34 ^\circ 36^{\prime} 45^{\prime\prime} , 48 EBs are detected and two are newly discovered. This specific field has been observed 52 times by the LAMOST Medium-Resolution Survey DR 9, which facilitates a comprehensive analysis of the EBs. For EBs with LAMOST medium-resolution spectra, radial velocity curves were obtained, and their precise orbital parameters were determined by simultaneously analyzing photometric light curves and radial velocity curves. For the other EBs with only photometric light curves, we used the q -search or the temperature ratio method to determine their initial mass ratios and then determined the orbital parameters. It is found that 15 EBs belong to detached systems, one to semi-detached systems, and 32 to contact systems. Based on the O − C analysis for 26 EBs with sufficient eclipsing times, we found a long-term decrease in the orbital period of 11 EBs and a continuous increase of five EBs, which are due to the material transfer between the two components. The O − C curve of 1 EB shows a distinct periodic variation, which is caused by the light travel time effect, and the third body is likely to be a black hole. By applying the spectral subtraction method to 13 EBs with LAMOST medium-resolution spectra, 10 systems exhibit distinct H α emission lines, in which one system exhibits double-peaked lines near phases 0.25 and 0.75, implying strong chromospheric activity. In the massluminosities and mass–radius distributions, most of the more massive components are less evolved than the less massive ones.}, archive = {J_ApJ}, author = {Jing-Yi Wang and Kai Li and Xiang Gao and Di-Fu Guo and Li-Heng Wang and Dong-Yang Gao and Ling-Zhi Li and Ya-Ni Guo and Xing Gao and Guo-You Sun}, doi = {10.3847/1538-4357/ad9929}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {69}, shortjournal = {The Astrophys. J.}, title = {Search for and analysis of eclipsing binaries in the LAMOST medium-resolution survey field. i. R.A.: 23h01m51s, decl.: +34°36′45″}, volume = {979}, year = {2025}, }
• (2025). JWST discovery of a very fast biconical outflow of warm molecular gas in the nearby ultraluminous infrared galaxy f08572+3915 NW. ApJ, 979(1), 68. (www)

  @article{ , abstract = {We present new James Webb Space Telescope (JWST) Mid-Infrared Instrument Medium-Resolution Spectrometer observations of the nearby ultraluminous infrared galaxy (ULIRG) F08572+3915 NW. These integral field spectroscopic (IFS) data reveal a kpc-scale warm-molecular rotating disk and biconical outflow traced by the H 2 ν = 0–0 S(1), S(2), S(3), and S(5) rotational transitions. The outflow maintains a relatively constant median (maximum) projected velocity of 1100 km s −1 (3000 km s −1 ) out to ∼1.4 kpc from the nucleus. The outflowing H 2 material is slightly warmer (640–700 K) than the rotating disk material (460–520 K), perhaps due to shock heating in the highly turbulent outflowing material. This outflow shares the same kinematics and orientation as the sub-kiloparsec scale warm H 2 outflow traced by the rovibrational H 2 lines in Keck AO near-infrared IFS data. However, this warm H 2 outflow is significantly faster than the sub-kiloparsec-scale cold molecular outflow derived from multi-transition far-infrared OH observations with Herschel and the greater than or equivalent to kiloparsec-scale cold molecular outflow mapped by millimeter-wave interferometric CO 1–0 observations with IRAM-PdBI and NOEMA. The new JWST data bolster the scenario where the buried quasar in this ULIRG is excavating the dust screen, accelerating perhaps as much as 60% of the dusty warm molecular material to velocities beyond the escape velocity, and thus influencing the evolution of the host galaxy.}, archive = {J_ApJ}, author = {Kylie Yui Dan and Jerome Seebeck and Sylvain Veilleux and David Rupke and Eduardo Gonzalez-Alfonso and Ismael Garcia-Bernete and Weizhe Liu and Dieter Lutz and Marcio Melendez and Miguel Pereira Santaella and Eckhard Sturm and Francesco Tombesi}, doi = {10.3847/1538-4357/ad9a50}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {68}, shortjournal = {The Astrophys. J.}, title = {JWST discovery of a very fast biconical outflow of warm molecular gas in the nearby ultraluminous infrared galaxy f08572+3915 NW}, volume = {979}, year = {2025}, }
• (2025). Alignment parameters: Quantifying dense core alignment in star-forming regions. ApJ, 979(1), 67. (www)

  @article{ , abstract = {Recent high-resolution observations at millimeter (mm) and submillimeter wavelengths reveal a diverse spatial distribution for subparsec-scale dense cores within star-forming regions, ranging from clustered to aligned arrangements. To address the increasing volume of observational and simulation data, we introduce "alignment parameters" as a quantitative and reproducible method to automatically assess core alignment. We first demonstrate the effectiveness of these parameters by applying them to artificial test clumps and comparing the results with labels from visual inspection. A threshold value is then proposed to differentiate between "clustered" and "aligned" categories. Subsequently, we apply these parameters to dense cores identified from a sample of Atacama Large Millimeter/submillimeter Array 1.3 mm dust continuum images in high-mass star-forming regions. Analysis exploring correlations between alignment parameters and clump properties rules out the presence of a moderate or strong correlation, indicating that clump properties do not appear to strongly influence the outcome of fragmentation. One possible explanation for this is that the fragmentation process is chaotic, meaning that small variations in initial conditions can lead to significant differences in fragmentation outcomes, thus obscuring any direct link between clump properties and core alignment/distribution.}, archive = {J_ApJ}, author = {Wei-An Chen and Ya-Wen Tang and S. D. Clarke and Patricio Sanhueza}, doi = {10.3847/1538-4357/ad9a5b}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {67}, shortjournal = {The Astrophys. J.}, title = {Alignment parameters: Quantifying dense core alignment in star-forming regions}, volume = {979}, year = {2025}, }
• (2025). From halos to galaxies. x. decoding galaxy SEDs with physical priors and accurate star formation history reconstruction. ApJ, 979(1), 66. (www)

  @article{ , abstract = {The spectral energy distribution (SED) of galaxies is essential for deriving fundamental properties like stellar mass and star formation history (SFH). However, conventional methods, including both parametric and nonparametric approaches, often fail to accurately recover the observed cosmic star formation rate (SFR) density due to oversimplified or unrealistic assumptions about SFH and their inability to account for the complex SFH variations across different galaxy populations. To address this issue, we introduce a novel approach that improves galaxy broadband SED analysis by incorporating physical priors derived from hydrodynamical simulations. Tests using IllustrisTNG simulations demonstrate that our method can reliably determine galaxy physical properties from broadband photometry, including stellar mass within 0.05 dex, current SFR within 0.3 dex, and fractional stellar formation time within 0.2 dex, with a negligible fraction of catastrophic failures. When applied to the Sloan Digital Sky Survey (SDSS) main photometric galaxy sample with spectroscopic redshift, our estimates of stellar mass and SFR are consistent with the widely used MPA-JHU and GSWLC catalogs. Notably, using the derived SFHs of individual SDSS galaxies, we estimate the cosmic SFR density and stellar mass density with remarkable consistency to direct observations up to z ~ 6. This demonstrates a significant advancement in deriving SFHs from SEDs that closely align with observational data. Consequently, our method can reliably recover observed spectral indices such as D n (4000) and H δ A by synthesizing the full spectra of galaxies using the estimated SFHs and metal enrichment histories, relying solely on broadband photometry as input. Furthermore, this method is extremely computationally efficient compared to conventional approaches.}, archive = {J_ApJ}, author = {Zeyu Gao and Yingjie Peng and Kai Wang and Luis C. Ho and Alvio Renzini and Anna R. Gallazzi and Filippo Mannucci and Houjun Mo and Yipeng Jing and Xiaohu Yang and Enci Wang and Dingyi Zhao and Jing Dou and Qiusheng Gu and Cheqiu Lyu and Roberto Maiolino and Bitao Wang and Yu-Chen Wang and Bingxiao Xu and Feng Yuan and Xingye Zhu}, doi = {10.3847/1538-4357/ad9a5c}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {66}, shortjournal = {The Astrophys. J.}, title = {From halos to galaxies. x. decoding galaxy SEDs with physical priors and accurate star formation history reconstruction}, volume = {979}, year = {2025}, }
• (2025). Examining turbulence in galactic molecular clouds. i. a statistical analysis of velocity structures. ApJ, 979(1), 65. (www)

  @article{ , abstract = {We present a systematic analysis of the velocity structure functions (VSFs) of 167 molecular clouds with angular sizes greater than ~176 arcmin 2 in three sectors of the Galactic midplane. We calculated the first-to-third-order VSFs and found that 60% of the VSFs exhibit power-law distributions. The relative power-law exponents are consistent with predictions from intermittent turbulence models. Column density weighting reduces the proportion of power-law VSFs and steepens the VSF slopes, implying a reduction of turbulent energy in high-density regions. All clouds show small-scale intermittency, with slightly stronger intermittency in those molecular clouds showing "none" power-law VSFs. Negative VSF exponents that may indicate gravitational collapse are not observed in our sample. The scaling exponents of the observed VSFs do not correlate with the virial parameters of the molecular clouds. These two observations suggest that gravity-dominated scales in molecular clouds still need further investigation. Consistent VSF scaling exponents for the molecular clouds with significant power-law VSFs suggest large-scale external driving of turbulence in these molecular clouds. However, the driving mechanisms are likely not universal, as the power-law scaling coefficients in our results show relatively large scatter. The fact that nearly 40% of the VSFs deviate to some extent from power-law distributions suggests that the influence of local environments on the internal turbulence of molecular clouds may not be negligible.}, archive = {J_ApJ}, author = {Yuehui Ma and Miaomiao Zhang and Hongchi Wang and Min Fang and Zhenyi Yue and Xuepeng Chen and Ji Yang and Fujun Du and Yang Su and Suziye He and Haoran Feng and Yan Sun and Chong Li and Qing-Zeng Yan and Zhiwei Chen and Shaobo Zhang and Xin Zhou}, doi = {10.3847/1538-4357/ad9b0e}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {65}, shortjournal = {The Astrophys. J.}, title = {Examining turbulence in galactic molecular clouds. i. a statistical analysis of velocity structures}, volume = {979}, year = {2025}, }
• (2025). A simulated galaxy laboratory: Exploring the observational effects on UV spectral absorption line measurements. ApJ, 979(1), 64. (www)

  @article{ , abstract = {Ultraviolet absorption line spectroscopy is a sensitive diagnostic for the properties of interstellar and circumgalactic gas. Down-the-barrel observations, where the absorption is measured against the galaxy itself, are commonly used to study feedback from galactic outflows and to make predictions about the leakage of H i ionizing photons into the intergalactic medium. Nonetheless, the interpretation of these observations is challenging, and observational compromises are often made in terms of signal-to-noise ratio, spectral resolution, or the use of stacking analyses. In this paper, we present a novel quantitative assessment of UV absorption line measurement techniques by using mock observations of a hydrodynamical simulation. We use a simulated galaxy to create 22,500 spectra in the commonly used Si ii lines while also modeling the signal-to-noise ratio and spectral resolution of recent rest-frame UV galaxy surveys at both high and low redshifts. We show that the residual flux of absorption features is easily overestimated for single line measurements and for stacked spectra. Additionally, we explore the robustness of the partial covering model for estimating column densities from spectra and find underpredictions on an average of 1.25 dex. We show that the underprediction is likely caused by high-column-density sight lines that are optically thick to dust making them invisible in UV spectra.}, archive = {J_ApJ}, author = {R. Michael Jennings and Alaina Henry and Valentin Mauerhofer and Timothy Heckman and Claudia Scarlata and Cody Carr and Xinfeng Xu and Mason Huberty and Simon Gazagnes and Anne E. Jaskot and Jeremy Blaizot and Anne Verhamme and Sophia R. Flury and Alberto Saldana-Lopez and Matthew J. Hayes and Maxime Trebitsch}, doi = {10.3847/1538-4357/ad9b13}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {64}, shortjournal = {The Astrophys. J.}, title = {A simulated galaxy laboratory: Exploring the observational effects on UV spectral absorption line measurements}, volume = {979}, year = {2025}, }
• (2025). Identifying coronal mass ejection active region sources: An automated approach. ApJ, 979(1), 63. (www)

  @article{ , abstract = {Identifying the source regions of coronal mass ejections (CMEs) is crucial for understanding their origins and improving space weather forecasting. We present an automated algorithm for matching CMEs detected by the Large Angle Spectrometric Coronagraph with their source active regions, specifically Space Weather HMI Active Region Patches (SHARPs), between 2010 May and 2019 January. Our method uses posteruptive signatures, including flares and coronal dimmings, to associate CMEs with potential source regions. Out of 4190 CMEs, we successfully match 1132, achieving a recall rate of ~57% for frontside events. We find that the algorithm performs better for complex SHARP regions containing multiple NOAA regions and for faster CMEs, consistent with expectations that more energetic events produce stronger eruption signatures. We find that CME–flare association rates increase with flare intensity, aligning with previous studies. While our approach has limitations, such as focusing exclusively on SHARP regions and relying on a limited set of posteruptive signatures, it significantly reduces the time required for CME source identification while providing transparent, reproducible results. We encourage the solar physics community to build upon this work, developing improved automated tools for CME source identification. The resulting catalog of CME–source region associations is made publicly available, offering a valuable resource for statistical studies and machine learning applications in solar physics and space weather forecasting.}, archive = {J_ApJ}, author = {Julio Hernandez Camero and Lucie M. Green and Alex Piñel Neparidze}, doi = {10.3847/1538-4357/ad9b27}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {63}, shortjournal = {The Astrophys. J.}, title = {Identifying coronal mass ejection active region sources: An automated approach}, volume = {979}, year = {2025}, }
• (2025). Observational study of recurrent jets: Evolution of magnetic flux, current, and helicity. ApJ, 979(1), 62. (www)

  @article{ , abstract = {We observed three recurrent blowout jets in an active region with the Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamics Observatory. Using Helioseismic Magnetic Imager data we found that the magnetic flux of an emerging negative pole increases steadily before declining just as the jets erupt. Certain physical quantities, such as the total unsigned vertical current, align with the periodicity of the jets. The differential affine velocity of vector magnetograms reveals strong shear around the negative pole. The Doppler velocity map, calculated from the H α spectra observed by the Chinese H α Solar Explorer, shows upflows with large initial velocity before they can be observed by AIA. The magnetic field derived from the nonlinear force-free field (NLFFF) model suggests a topology akin to a fan–spine structure, consistent with AIA images. We calculated the evolution of the volumetric helicity ratio using the NLFFF model and found its phase aligns with the jet flux in AIA 171 Å. These results suggest that recurrent jets may be triggered by the accumulation and release of energy and helicity, driven by emergence, shearing, and cancellation of photospheric magnetic field.}, archive = {J_ApJ}, author = {Chang Zhou and Yang Guo and Guoyin Chen and Ye Qiu and M.D. Ding}, doi = {10.3847/1538-4357/ad9b7d}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {62}, shortjournal = {The Astrophys. J.}, title = {Observational study of recurrent jets: Evolution of magnetic flux, current, and helicity}, volume = {979}, year = {2025}, }
• (2025). On disk formation around isolated black holes via stream accretion. ApJ, 979(1), 61. (www)

  @article{ , abstract = {We investigate accretion onto an isolated black hole from uniform winds. If the winds are directed toward the black hole, then the accretion process can be well described by the classical Bondi–Hoyle–Lyttleton or BHL accretion. If the wind is not directed toward the black hole and flows past it, then a smaller fraction of the flow can be attracted by the black hole, and this type of accretion cannot be described by the classical BHL, and we coin the second kind as the lateral BHL. We show that the classical BHL cannot form an accretion disk, while lateral BHL can form transient accretion disks. To describe the thermodynamics of the flow, we have used a variable adiabatic index equation of state which depends on the temperature of the flow as well as the composition of the gas. We show that the electron-proton gas forms an accretion disk, which disappears and forms a shock cone, only to form the disk again at a later time, while for flows with fewer protons, the accretion disk, once lost, does not reappear again. Only when the flow is pair-dominated does it form a persistent accretion disk. We also show that a shock cone is less luminous than the accretion disk.}, archive = {J_ApJ}, author = {Priyesh Kumar Tripathi and Indranil Chattopadhyay and Raj Kishor Joshi}, doi = {10.3847/1538-4357/ad9b96}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {61}, shortjournal = {The Astrophys. J.}, title = {On disk formation around isolated black holes via stream accretion}, volume = {979}, year = {2025}, }
• (2025). Comparison of bar formation mechanisms. i. does a tidally induced bar rotate slower than an internally induced bar?. ApJ, 979(1), 60. (www)

  @article{ , abstract = {Galactic bars can form via the internal bar instability or external tidal perturbations by other galaxies. We systematically compare the properties of the bars formed through the two mechanisms with a series of controlled N -body simulations that form bars through internal or external mechanisms. We create three disk galaxy models with different dynamical "hotness" and evolve them in isolation and under flyby interactions. In the cold- and warm-disk models, where bars can form spontaneously in isolation, tidally induced bars are promoted to a more "advanced" evolutionary stage. However, these bars have similar pattern speeds to those formed spontaneously within the same disk. Bars formed from both mechanisms have similar distributions in pattern-speed–bar-strength (Ω p − A 2 ) space and exhibit comparable ratios of corotation radius to bar length ( { \mathcal R }={R}_{{\rm{CR}}}/{R}_{{\rm{bar}}} ). Dynamical analyses suggest that the inner stellar disk loses the same amount of angular momentum, irrespective of the presence or intensity of the perturbation, which possibly explains the resemblance between tidally and spontaneously formed bars. In the hot-disk model, which avoids the internal bar instability in isolation, a bar forms only under perturbations and rotates more slowly than those in the cold and warm disks. Thus, if "tidally induced bars" refer exclusively to those in galaxies that are otherwise stable against bar instability, they indeed rotate slower than internally induced ones. However, the pattern speed difference is due to the difference in the internal properties of the bar host galaxies, not the different formation mechanisms.}, archive = {J_ApJ}, author = {Yirui Zheng and Juntai Shen}, doi = {10.3847/1538-4357/ad9bae}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {60}, shortjournal = {The Astrophys. J.}, title = {Comparison of bar formation mechanisms. i. does a tidally induced bar rotate slower than an internally induced bar?}, volume = {979}, year = {2025}, }
• (2025). Investigating the lower limit of metallicity for the galactic thin disk. ApJ, 979(1), 59. (www)

  @article{ , abstract = {We explore the metal-poor regime of the Galactic disk on the distribution of stars in the [ α /M]– V ϕ plane, to identify the most metal-poor thin disk (MPTnD) stars belonging to the low- α sequence. Chemical abundances and velocities of sample stars are either taken or derived from APOGEE DR17 and Gaia DR3 catalogs. We find the existence of a well-separated extension of the kinematically thin disk stars in the metallicity range of −1.2 < [M/H] < −0.8 dex. Based on two-by-two distributions of [Mg/Mn], [Al/Fe] and [C+N/Fe], we further confirmed 56 high-possibility metal-poor thin disk (HP-MPTnD) giant stars and suggested the lower metallicity limit of the thin disk below −0.95 dex. A comparative analysis of the HP-MPTnD sample with other Galactic components revealed its chemo-dynamical similarities with canonical thin disk stars. These low- α metal-poor stars are predominantly located in the outer disk region and formed in the early stage of the formation of thin disk. Their existence provides compelling support for the two-infall model of the Milky Way's disk formation. Moreover, these stars impose observational constraints on the timing and metallicity of the second gas infall event.}, archive = {J_ApJ}, author = {Guozhen Hu and Zhengyi Shao and Erbil Gügercinoǧlu and Wenyuan Cui}, doi = {10.3847/1538-4357/ad9c38}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {59}, shortjournal = {The Astrophys. J.}, title = {Investigating the lower limit of metallicity for the galactic thin disk}, volume = {979}, year = {2025}, }
• (2025). Nuclear and star formation activities in nearby galaxies: Roles of gas supply and active galactic nucleus feedback. ApJ, 979(1), 58. (www)

  @article{ , abstract = {We analyze a sample of  ~113,000 galaxies ( z < 0.3) from the Sloan Digital Sky Survey, divided into star-forming, composite, Seyfert, and LINER types, to explore the relationships between UV-to-optical colors ( u – r ), star formation rates (SFRs), specific SFRs (sSFRs), stellar velocity dispersions ( σ * ), mass accretion rates onto the black hole ( {L}_{[{\rm{O}}\,{\rm{III}}]}/{\sigma }_{\ast }^{4} ), and Eddington ratios. Star-forming galaxies predominantly feature young, blue stars along the main-sequence (MS) line, while composite, Seyfert, and LINER galaxies deviate from this line, displaying progressively older stellar populations and lower SFRs. The {L}_{[{\rm{O}}\,{\rm{III}}]}/{\sigma }_{\ast }^{4} and Eddington ratios are highest in Seyfert galaxies, moderate in composite galaxies, and lowest in LINERs, with higher ratios associated with bluer colors, indicating a younger stellar population and stronger active galactic nucleus (AGN) activity. These trends suggest a strong correlation between sSFRs and Eddington ratios, highlighting a close connection between AGN and star formation activities. These results may imply an evolutionary sequence where galaxies transition from blue star-forming galaxies to red LINERs, passing through the composite and Seyfert phases, driven primarily by gas supply, with AGN feedback playing a secondary role. While both the radio luminosities ( L 1.4 GHz ) and Eddington ratios correlate with SFRs, their trends differ on the SFR−stellar-mass ( M * ) plane, with the radio luminosities increasing with stellar mass along the MS line and no direct connection between the radio luminosities and Eddington ratios. These findings may provide new insights into the interplay between star formation, AGN activity, and radio emission in galaxies, shedding light on their evolutionary pathways.}, archive = {J_ApJ}, author = {Huynh Anh N. Le and Yongquan Xue}, doi = {10.3847/1538-4357/ad9d38}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {58}, shortjournal = {The Astrophys. J.}, title = {Nuclear and star formation activities in nearby galaxies: Roles of gas supply and active galactic nucleus feedback}, volume = {979}, year = {2025}, }
• (2025). The effect of donor star rejuvenation on common envelope evolution. ApJ, 979(1), 57. (www)

  @article{ , abstract = {In close binary star systems, common envelope evolution (CEE) may occur after a previous phase of mass transfer. Some isolated formation channels for double neutron star binaries suggest that the donor of CEE was the accretor of a previous phase of stable mass transfer. Accretion should substantially alter the structure of the donor, particularly by steepening the density gradient at the core-envelope interface and rejuvenating the star. We study the CEE of a donor that was the accretor of a previous phase of stable mass transfer and has a rejuvenated structure. We perform 3D hydrodynamics simulations of the CEE of an 18 M ⊙ supergiant with a 1.4 M ⊙ companion using rejuvenated and non-rejuvenated 1D stellar models for the donor. We compare the two simulations to characterize the effect of the rejuvenation on the outcome of the common envelope phase and the shape of the ejecta. We find that accounting for a previous phase of mass transfer reduces the duration of the inspiral phase by a factor of two, likely due to the different structures in the outer layers of the donor. In the rejuvenated case, the simulations show more equatorially concentrated and asymmetric ejecta, though both cases display evidence for the formation of a pressure-supported thick circumbinary disk. During the dynamical inspiral phase, the impact of rejuvenation on the unbinding of the envelope is unclear; we find that rejuvenation decreases the amount of unbound mass by 20%–40% depending on the energy criterion used.}, archive = {J_ApJ}, author = {C. Landri and P. M. Ricker and M. Renzo and S. Rau and A. Vigna-Gómez}, doi = {10.3847/1538-4357/ad9d3c}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {57}, shortjournal = {The Astrophys. J.}, title = {The effect of donor star rejuvenation on common envelope evolution}, volume = {979}, year = {2025}, }
• (2025). Characterizing multiband optical emission and variability of 1ES 1215+303 on diverse timescales. ApJ, 979(1), 56. (www)

  @article{ , abstract = {This study presents analyses of the optical variability of the 1ES 1215+303 on diverse timescales using multiband observations, including observations in the optical BVRI bands carried out with the 0.6 and 1.0 m telescopes located at the Tübitak National Observatory (TUG) from 2022 to 2024 and Zwicky Transient Facility (ZTF) gri data from 2018 to 2023. Investigation of variability on intraday timescales revealed amplitudes of 4.0% and 5.6% on two nights, with a calculated duty cycle of 63%. We determined a minimum timescale of ~92 minutes from these observations, leading us to limit the radius for the optical emission region and the mass of the black hole. The blazar exhibits moderate short- and long-term variability, with variability amplitudes reaching up to 120% and decreasing as the wavelength shortens. Correlation analysis revealed a strong correlation between the optical multiband emissions without any time lag. Analysis of 109 nightly spectral energy distributions yielded spectral indices ranging from 0.772 to 1.413. The consistent trend of both spectral indices and color with respect to brightness suggests a mild bluer when brighter trend persists throughout the observation period, in contrast to the intraday timescale. Utilizing the weighted wavelet z -transform and Lomb–Scargle methods, we analyzed recurrent optical emission patterns on the combined R -band light curves from TUG, ZTF, and Tuorla observations, revealing a quasiperiodic signal at around 1000 days and a secondary signal at approximately 300 days. These signals were found to be insignificant after accounting for the stochastic process and the trial factor.}, archive = {J_ApJ}, author = {A. Ozdonmez and H. Er and M. Tekkesinoglu and E. Ege and M. E. Kenger and I. C. Ozkesen and A. Polatoğlu}, doi = {10.3847/1538-4357/ad9d45}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {56}, shortjournal = {The Astrophys. J.}, title = {Characterizing multiband optical emission and variability of 1ES 1215+303 on diverse timescales}, volume = {979}, year = {2025}, }
• (2025). Einasto profile as the halo model solution coupled to the depletion radius. ApJ, 979(1), 55. (www)

  @article{ , abstract = {We constrain the halo profiles outside the halo boundaries by solving for the matching profiles required by the halo model. In the halo model framework, the matter distribution in the Universe can be decomposed into the spatial distribution of halos convolved with their internal structures. This leads to a set of linear equations in Fourier space that uniquely determines the matching halo profiles for any given halo catalog. In this work, we construct three halo catalogs with different boundary definitions and solve for the matching profiles in each case using measurements of halo–matter and halo–halo power spectra. Our results show that for a given halo field, there is always a set of matching profiles to accurately reconstruct the input statistics of the matter field, even though it might be complex to model the profiles analytically. Comparing the solutions from different halo catalogs, we find that their mass distributions inside the inner depletion radii are nearly identical, while they deviate from each other on larger scales, with a larger boundary resulting in a more extended profile. For the depletion-radius-based catalog, the numerical solution agrees well with the Einasto profile. Coupling the Einasto profile with the depletion catalog, the resulting halo model can simultaneously predict the halo–matter power spectra to 10% and the matter–matter power spectrum to 5%, improving over conventional models in both interpretability and versatility. The conditions and limitations of using the Navarro–Frenk–White profile in the halo model are also discussed.}, archive = {J_ApJ}, author = {Yifeng Zhou and Jiaxin Han}, doi = {10.3847/1538-4357/ad9de8}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {55}, shortjournal = {The Astrophys. J.}, title = {Einasto profile as the halo model solution coupled to the depletion radius}, volume = {979}, year = {2025}, }
• (2025). Local 2D simulations of the ignition of a helium shell detonation on a white dwarf by an impacting stream. ApJ, 979(1), 54. (www)

  @article{ , abstract = {The double detonation model is one of the prevalent explosion mechanisms of Type Ia supernovae (SNe Ia) wherein an outer helium shell detonation triggers a core detonation in the white dwarf (WD). The dynamically driven double degenerate double detonation (D 6 ) is the double detonation of the more massive WD in a binary WD system where the localized impact of the mass transfer stream from the companion sets off the initial helium shell detonation. To have high numerical resolution and control over the stream parameters, we have implemented a study of the local interaction of the stream with the WD surface in 2D. In cases with lower base density of the shell, the stream's impact can cause surface detonation soon after first impact. With higher base densities, after the stream hits the surface, hot material flows around the star and interacts with the incoming stream to produce a denser and narrower impact. Our results therefore show that (1) a directly impacting stream for both a relatively high resolution and for a range of stream parameters can produce a surface detonation, (2) thinner helium shells ignite more promptly via impact, doing so sooner, and (3) there are lower limits on ignition in both shell density and incoming stream speed with lower limits on density being well below those shown by other work to be required for normal appearing SN Ia. This supports stream ignition and therefore the D 6 scenario, as a viable mechanism for normal SNe Ia.}, archive = {J_ApJ}, author = {Nethra Rajavel and Dean M. Townsley and Ken J. Shen}, doi = {10.3847/1538-4357/ada034}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {54}, shortjournal = {The Astrophys. J.}, title = {Local 2D simulations of the ignition of a helium shell detonation on a white dwarf by an impacting stream}, volume = {979}, year = {2025}, }
• (2025). Magnetic flux emergence and solar eruptions in partially ionized plasmas. ApJ, 979(1), 53. (www)

  @article{ , abstract = {We have performed 3D MHD simulations to study the effect of partial ionization in the process of magnetic flux emergence in the Sun. In fact, we continue previous work, and we now focus (1) on the emergence of the magnetic fields above the solar photosphere and (2) on the eruptive activity that follows the emergence into the corona. We find that in the simulations with partial ionization (PI), the structure of the emerging field consists of arch-like field lines with very little twist since the axis of the initial rising field remains below the photosphere. The plasma inside the emerging volume is less dense, and it is moving faster compared to the fully ionized (FI) simulation. In both cases, new flux ropes (FR) are formed due to reconnection between emerging field lines, and they eventually erupt in an ejective manner toward the outer solar atmosphere. We are witnessing three major eruptions in both simulations. At least for the first eruption, the formation of the eruptive FR occurs in the low atmosphere in the FI case and at coronal heights in the PI case. Also, in the first PI eruption, part of the eruptive FR carries neutrals in the high atmosphere for a short period of time. Overall, the eruptions are relatively faster in the PI case, while a considerable amount of axial flux is found above the photosphere during the eruptions in both simulations.}, archive = {J_ApJ}, author = {Georgios Chouliaras and V. Archontis}, doi = {10.3847/1538-4357/ada0af}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {53}, shortjournal = {The Astrophys. J.}, title = {Magnetic flux emergence and solar eruptions in partially ionized plasmas}, volume = {979}, year = {2025}, }
• (2025). Advancing CO2++ modeling in the martian dayside ionosphere: Insights from natural lifetime analysis. ApJ, 979(1), 52. (www)

  @article{ , abstract = {The molecular dication CO 2 ++ has, as previously reported, been detected in the Martian ionosphere by the Neutral Gas and Ion Mass Spectrometer on the Mars Atmosphere and Volatile Evolution (MAVEN) mission. Photochemical models have also been developed to reproduce the CO 2 ++ density in the Martian dayside ionosphere but underestimate significantly the observations. In this study, we examine the influence of the CO 2 ++ natural lifetime against spontaneous dissociation on its modeled density. We show that extending the assumed CO 2 ++ lifetime significantly reduces the discrepancy between the photochemical model predictions and MAVEN observations. Specifically, when treating CO 2 ++ as stable against natural dissociation, instead of invoking a lifetime of 4 s as done in previous studies, the data-to-model ratio comes close to unity throughout the altitude range 160–220 km. We argue that stability of CO 2 ++ against natural dissociation does not necessarily conflict with results from a frequently cited experimental investigation. Our study provides new insights for advancing photochemical modeling of the Martian ionosphere and underscores the need for further laboratory measurements targeting fundamental properties of doubly charged ions.}, archive = {J_ApJ}, author = {Long Cheng and Erik Vigren and Moa Persson and Hao Gu and Jun Cui}, doi = {10.3847/1538-4357/ada123}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {52}, shortjournal = {The Astrophys. J.}, title = {Advancing CO2++ modeling in the martian dayside ionosphere: Insights from natural lifetime analysis}, volume = {979}, year = {2025}, }
• (2025). Cosmic chronometers, pantheon+ supernovae, and quasars favor coasting cosmologies over the flat ΛCDM model. ApJ, 979(1), 51. (www)

  @article{ , abstract = {We test and compare coasting cosmological models with curvature parameters k=\left\{-1,0,+1\right\} in {H}_{0}^{2}{c}^{-2} units and the flat ΛCDM model by fitting them to cosmic chronometers (CCs), the Pantheon+ sample of Type Ia supernovae (SNe), and standardized quasars (QSOs). We used the emcee code for fitting CC data, a custom Markov Chain Monte Carlo implementation for SNe and QSOs, and Anderson–Darling tests for normality on normalized residuals for model comparison. Best-fit parameters are presented, constrained by data within redshift ranges z ≤ 2 for CCs, z ≤ 2.3 for SNe, and z ≤ 7.54 for QSOs. Coasting models, particularly the flat coasting model, are generally favored over the flat ΛCDM model. The overfitting of the flat ΛCDM model to Pantheon+ SNe and the large intrinsic scatter in QSO data suggest a need to refine error estimates in these data sets. We also highlight the seemingly fine-tuned nature of either the CC data or Ω m ,0 in the flat ΛCDM model to an H 1 = H 0 coincidence when fitting H ( z ) = H 1 z + H 0 , a natural feature of coasting models.}, archive = {J_ApJ}, author = {Peter Raffai and Adrienn Pataki and Rebeka L. Böttger and Alexandra Karsai and Gergely Dálya}, doi = {10.3847/1538-4357/ada249}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {51}, shortjournal = {The Astrophys. J.}, title = {Cosmic chronometers, pantheon+ supernovae, and quasars favor coasting cosmologies over the flat ΛCDM model}, volume = {979}, year = {2025}, }
• (2025). Time-dependent acceleration and escape of charged particles at traveling shocks in the near-sun environment. ApJ, 979(1), 50. (www)

  @article{ , abstract = {Current multi-spacecraft in situ measurements allow for the investigation of the time evolution of energetic particles at interplanetary shocks (IPs) at small (≲0.1 au) heliocentric distances. The energy spectrum of accelerated particles at IPs was shown by a previous 1D transport model that includes both self-excited plus preexisting turbulence and a term representing the escape of particles from the system to gradually steepen as a result of a finite acceleration-to-escape timescales ratio; such a model was found in excellent agreement with the entire sample of the ground-level enhancement spectra of solar cycle 23. We solve the time-dependent case of such a model in the case of diffusion dominated by preexisting turbulence. The average timescale for particle acceleration at various heliocentric distances, from 1 au down to the inner heliosphere (<0.1 au), is shorter than in the no-escape case, as higher energy particles have a shorter time to accelerate before completely leaving the system into the upstream medium. A simple scaling with time of the time-dependent spectrum is provided. We compare the "nose" structure at a few ∼100s keV protons first measured in situ by Parker Solar Probe in crossing the very fast 2022 September 5 shock at 0.07 au; we find that the nose is reasonably well explained by a lack of the highest energy particles not yet produced by the young shock by both our model and the no-escape version.}, archive = {J_ApJ}, author = {Thomas M. Do and Federico Fraschetti and Jozsef Kota and Joe Giacalone and Christina M. S. Cohen and David J. McComas}, doi = {10.3847/1538-4357/ad93b2}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {50}, shortjournal = {The Astrophys. J.}, title = {Time-dependent acceleration and escape of charged particles at traveling shocks in the near-sun environment}, volume = {979}, year = {2025}, }
• (2025). The solar and geomagnetic storms in 2024 may: A flash data report. ApJ, 979(1), 49. (www)

  @article{ , abstract = {In 2024 May, the scientific community observed intense solar eruptions that resulted in a great geomagnetic storm and auroral extensions, highlighting the need to document and quantify these events. This study mainly focuses on their quantification. The source active region (AR; NOAA Active Region 13664) evolved from 113 to 2761 millionths of the solar hemisphere between May 4 and 14. NOAA AR 13664's magnetic free energy surpassed 10 33 erg on May 7, triggering 12 X-class flares on May 8–15. Multiple interplanetary coronal mass ejections (ICMEs) were produced from this AR, accelerating solar energetic particles toward Earth. According to satellite and interplanetary scintillation data, at least four ICMEs erupted from AR 13664, eventually overcoming and combining each other. The shock arrival at 17:05 UT on May 10 significantly compressed the magnetosphere down to ≈5.04 R E and triggered a deep Forbush Decrease. GOES satellite data and ground-based neutron monitors confirmed a ground-level enhancement from 2 UT to 10 UT on 2024 May 11. The ICMEs induced exceptional geomagnetic storms, peaking at a provisional Dst index of −412 nT at 2 UT on May 11, marking the sixth-largest storm since 1957. The AE and AL indices showed great auroral extensions that located the AE/AL stations into the polar cap. We gathered auroral records at that time and reconstructed the equatorward boundary of the visual auroral oval to 29 8 invariant latitude. We compared naked-eye and camera auroral visibility, providing critical caveats on their difference. We also confirmed global disturbances of the storm-enhanced density of the ionosphere.}, archive = {J_ApJ}, author = {Hisashi Hayakawa and Yusuke Ebihara and Alexander Mishev and Sergey Koldobskiy and Kanya Kusano and Sabrina Bechet and Seiji Yashiro and Kazumasa Iwai and Atsuki Shinbori and Kalevi Mursula and Fusa Miyake and Daikou Shiota and Marcos V. D. Silveira and Robert Stuart and Denny M. Oliveira and Sachiko Akiyama and Kouji Ohnishi and Vincent Ledvina and Yoshizumi Miyoshi}, doi = {10.3847/1538-4357/ad9335}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {49}, shortjournal = {The Astrophys. J.}, title = {The solar and geomagnetic storms in 2024 may: A flash data report}, volume = {979}, year = {2025}, }
• (2025). Recovering pulsar periodicity from time-of-arrival data by finding the shortest vector in a lattice. ApJ, 979(1), 48. (www)

  @article{ , abstract = {The strict periodicity of pulsars is one of the primary ways through which their nature and environment can be studied, and it has also enabled precision tests of general relativity and studies of nanohertz gravitational waves using pulsar timing arrays (PTAs). Identifying such a periodicity from a discrete set of arrival times is a difficult algorithmic problem, In particular when the pulsar is in a binary system. This challenge is especially acute in γ -ray pulsar astronomy, as there are hundreds of unassociated Fermi-LAT sources that may be produced by γ -ray emission from unknown pulsars. Recovering their timing solutions will help reveal their properties and may allow them to be added to PTAs. The same issue arises when attempting to recover a strict periodicity for repeating fast radio bursts (FRBs). Such a detection would be a major breakthrough, providing us with the FRB source's age, magnetic field, and binary orbit. The problem of recovering a timing solution from sparse time-of-arrival data is currently unsolvable for pulsars in unknown binary systems, and incredibly hard even for isolated pulsars. In this paper, we frame the timing recovery problem as the problem of finding a short vector in a lattice and obtain the solution using off-the-shelf lattice reduction and sieving techniques. As a proof of concept, we solve PSR J0318+0253, a millisecond γ -ray pulsar discovered by FAST in a γ -ray-directed search, in a few CPU minutes. We discuss the assumptions of the standard lattice techniques and quantify their performance and limitations.}, archive = {J_ApJ}, author = {Dotan Gazith and Aaron B. Pearlman and Barak Zackay}, doi = {10.3847/1538-4357/ad9449}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {48}, shortjournal = {The Astrophys. J.}, title = {Recovering pulsar periodicity from time-of-arrival data by finding the shortest vector in a lattice}, volume = {979}, year = {2025}, }
• (2025). Suzaku observations of the cold front in a3667: A nonequilibrium ionization state of the intracluster medium. ApJ, 979(1), 47. (www)

  @article{ , abstract = {We present a systematic study of the thermodynamic properties of the intracluster medium (ICM), including the plasma conditions in the ICM, in the merging galaxy cluster A3667 using Suzaku. We analyze the X-ray spectra of the ICM between the northwestern and the southeastern radio relics across a prominent cold front in A3667 to search for the ICM in a nonequilibrium ionization (NEI) state. We find that the ICM inside the cold front exhibits an NEI state with an ionization parameter of (2.2 ± 0.4) × 10 11 s cm −3 at the 90% confidence level, which is lower than that expected from a collisional ionization equilibrium state of the ICM (i.e., n e t > 10 12 s cm −3 ). The timescale calculated from the ionization parameter of the ICM inside the cold front is {3.9}_{-0.8}^{+0.7}\,\mathrm{Myr} , which is much shorter than the thermal equilibration timescale. A weak transonic sloshing motion might explain the possibility that the ICM inside the cold front of A3667 is in the NEI state. In addition, the NEI state of the ICM in A3667 seems to be associated with the elongated radio halo bridging the region between the northwestern radio relic and the prominent cold front in A3667 across the cluster center.}, archive = {J_ApJ}, author = {Mona Shishido and Yuusuke Uchida and Takayoshi Kohmura}, doi = {10.3847/1538-4357/ad96ac}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {47}, shortjournal = {The Astrophys. J.}, title = {Suzaku observations of the cold front in a3667: A nonequilibrium ionization state of the intracluster medium}, volume = {979}, year = {2025}, }
• (2025). The effect of stellar evolution on dispersal of protoplanetary disks: Disk fraction in star-forming regions. ApJ, 979(1), 46. (www)

  @article{ , abstract = {We study the effect of stellar evolution on the dispersal of protoplanetary disks by performing one-dimensional simulations of long-term disk evolution. Our simulations include viscous disk accretion, magnetohydrodynamic winds, and photoevaporation as important disk dispersal processes. We consider a wide range of stellar mass of 0.1–7 M ⊙ and incorporate the luminosity evolution of the central star. For solar-mass stars, stellar evolution delays the disk dispersal time as the far-ultraviolet (FUV) luminosity decreases toward the main sequence. In the case of intermediate-mass stars, the FUV luminosity increases significantly over a few million years, driving strong photoevaporation and enhancing disk mass loss during the later stages of disk evolution. This highlights the limitations of assuming a constant FUV luminosity throughout a simulation. Photoevaporation primarily impacts the outer regions of the disk and is the dominant disk dispersal process in the late evolutionary stage. Based on the results of a large set of simulations, we study the evolution of a population of star–disk systems and derive the disk fraction as a function of time. We demonstrate that the inclusion of stellar luminosity evolution can alter the disk fraction by several tens of percent, bringing the simulations into closer agreement with recent observations. We argue that it is important to include the stellar luminosity evolution in simulations of the long-term dispersal of protoplanetary disks.}, archive = {J_ApJ}, author = {Ayano Komaki and Naoki Yoshida}, doi = {10.3847/1538-4357/ad9746}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {46}, shortjournal = {The Astrophys. J.}, title = {The effect of stellar evolution on dispersal of protoplanetary disks: Disk fraction in star-forming regions}, volume = {979}, year = {2025}, }
• (2025). Increased surface temperatures of habitable white dwarf worlds relative to main-sequence exoplanets. ApJ, 979(1), 45. (www)

  @article{ , abstract = {Discoveries of giant planet candidates orbiting white dwarf (WD) stars and the demonstrated capabilities of the James Webb Space Telescope bring the possibility of detecting rocky planets in the habitable zones (HZs) of WDs into pertinent focus. We present simulations of an aqua planet with an Earth-like atmospheric composition and incident stellar insolation orbiting in the HZ of two different types of stars—a 5000 K WD and main-sequence K-dwarf star Kepler-62 (K62) with a similar effective temperature—and identify the mechanisms responsible for the two differing planetary climates. The synchronously rotating WD planet's global mean surface temperature is 25 K higher than that of the synchronously rotating planet orbiting K62, due to its much faster (10 hr) rotation and orbital period. This ultrafast rotation generates strong zonal winds and meridional flux of zonal momentum, stretching out and homogenizing the scale of atmospheric circulation, and preventing an equivalent buildup of thick, liquid water clouds on the dayside of the planet compared to the synchronous planet orbiting K62, while also transporting heat equatorward from higher latitudes. White dwarfs may therefore present amenable environments for life on planets formed within or migrated to their HZs, generating warmer surface environments than those of planets with main-sequence hosts to compensate for an ever shrinking incident stellar flux.}, archive = {J_ApJ}, author = {Aomawa L. Shields and Eric T. Wolf and Eric Agol and Pier-Emmanuel Tremblay}, doi = {10.3847/1538-4357/ad9827}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {45}, shortjournal = {The Astrophys. J.}, title = {Increased surface temperatures of habitable white dwarf worlds relative to main-sequence exoplanets}, volume = {979}, year = {2025}, }
• (2025). Some stars fade quietly: Varied supernova explosion outcomes and their effects on the multiphase interstellar medium. ApJ, 979(1), 44. (www)

  @article{ , abstract = {We present results from galaxy evolution simulations with a multiphase interstellar medium (ISM), a mass resolution of 4 M ⊙ , and a spatial resolution of 0.5 pc. These simulations include a resolved stellar stellar feedback model. Our fiducial run WLM-fid adopts 10 51 erg for the supernova (SN) energy. Among the remaining seven simulations, there are two runs where we vary this number by fixing the energy at 10 50 erg and 10 52 erg (WLM-1e50 and WLM-1e52). Additionally, we carry out one run with variable SN-energy (WLM-variable) and run two simulations where only 10% or 60% of stars explode as SNe with 10 51 erg, while the remaining stars do not explode (WLM-60prob and WLM-10prob). We find that the variation in the SN energy, has only minor effects: the star formation rate changes by roughly a factor of 2 compared to WLM-fid, and the strength of the galactic outflows in mass and energy is reduced by 30%, with typical values of η m ∼ 0.1 and η e ∼ 0.05 (at a height of 3 kpc after the hot wind is fully decoupled from the galactic ISM). In contrast, the increase and decrease in the canonical SN-energy have a clear impact on the phase structure, with loading factors that are at least 10 times lower/higher and a clear change in the phase structure (the energy loading is normalized self-consistently to the initial mass function averaged explosion energy). We conclude that these modulations are driven not by the minor change in SN-energy but rather by the likelihood of whether or not an event occurs when variable SN energies are applied.}, archive = {J_ApJ}, author = {Ulrich P. Steinwandel and Jared A. Goldberg}, doi = {10.3847/1538-4357/ad98ea}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {44}, shortjournal = {The Astrophys. J.}, title = {Some stars fade quietly: Varied supernova explosion outcomes and their effects on the multiphase interstellar medium}, volume = {979}, year = {2025}, }
• (2025). Tempered superdiffusive shock acceleration at a perpendicular shock. ApJ, 979(1), 43. (www)

  @article{ , abstract = {A theory for steady-state tempered superdiffusive shock acceleration of energetic particles at a plane perpendicular shock is presented that involves solving analytically a tempered fractional Parker transport equation for perpendicular transport in quasi-2D turbulence. The main predictions of the theory are as follows: (i) Tempered perpendicular superdiffusion (tempered Lévy flights) upstream reduces the effectiveness of classical perpendicular superdiffusion (standard Lévy flights) through a transition toward normal perpendicular diffusion when the particle transport distance upstream surpasses a critical spatial scale. Consequently, the accelerated particle distribution upstream decays spatially as a stretched exponential close to the shock that becomes a power law farther upstream under some conditions (superdiffusion), followed by an exponential rollover (transition to normal diffusion); (ii) Downstream, the accelerated particle distribution for tempered superdiffusion converges to a uniform distribution closer to the shock because of a stronger decay close to the shock compared to classical superdiffusion, and a shift of the peak in the distribution at the shock to just downstream of the shock occurs under some conditions; (iii) The accelerated power-law momentum spectrum at the shock is modulated upstream by the incoming solar wind flow to be a hardened power law instead of featuring an exponential rollover at lower particle momenta as for classical diffusive shock acceleration; and (iv) Tempered superdiffusive shock acceleration tends to be more efficient compared to standard superdiffusive shock acceleration.}, archive = {J_ApJ}, author = {J. A. le Roux and R. K. Shikha}, doi = {10.3847/1538-4357/ad98f2}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {43}, shortjournal = {The Astrophys. J.}, title = {Tempered superdiffusive shock acceleration at a perpendicular shock}, volume = {979}, year = {2025}, }
• (2025). From halos to galaxies. VI. improved halo mass estimation for SDSS groups and measurement of the halo mass function. ApJ, 979(1), 42. (www)

  @article{ , abstract = {In ΛCDM cosmology, galaxies form and evolve in their host dark matter (DM) halos. Halo mass is crucial for understanding the halo–galaxy connection. The abundance-matching (AM) technique has been widely used to derive the halo masses of galaxy groups. However, the quenching of the central galaxy can decouple the coevolution of its stellar mass and DM halo mass. Different halo assembly histories can also result in significantly different final stellar masses of the central galaxies. These processes can introduce substantial uncertainties into the halo masses derived from the AM method, particularly leading to a systematic bias between groups with star-forming centrals (blue groups) and passive centrals (red groups). To improve this, we have developed a new machine learning (ML) algorithm that accounts for these effects and is trained on simulations. Our results show that the ML method eliminates the systematic bias in the derived halo masses for blue and red groups and is, on average, ~one-third more accurate than the AM method. With careful calibrations of observable quantities from simulations and observations from the Sloan Digital Sky Survey (SDSS), we apply our ML model to the SDSS groups to derive their halo masses down to 10 11.5 M ⊙ or even lower. The derived SDSS group halo mass function agrees well with the theoretical predictions, and the derived stellar-to-halo mass relations for both the red and blue groups match well with those obtained from direct weak-lensing measurements. These new halo mass estimates enable more accurate investigation of the galaxy–halo connection and the role of halos in galaxy evolution.}, archive = {J_ApJ}, author = {Dingyi Zhao and Yingjie Peng and Yipeng Jing and Xiaohu Yang and Luis C. Ho and Alvio Renzini and Anna R. Gallazzi and Cheqiu Lyu and Roberto Maiolino and Jing Dou and Zeyu Gao and Qiusheng Gu and Filippo Mannucci and Houjun Mo and Bitao Wang and Enci Wang and Kai Wang and Yu-Chen Wang and Bingxiao Xu and Feng Yuan and Xingye Zhu}, doi = {10.3847/1538-4357/ad991f}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {42}, shortjournal = {The Astrophys. J.}, title = {From halos to galaxies. VI. improved halo mass estimation for SDSS groups and measurement of the halo mass function}, volume = {979}, year = {2025}, }
• (2025). The importance of gas starvation in driving satellite quenching in galaxy groups at z ~ 0.8. ApJ, 979(1), 41. (www)

  @article{ , abstract = {We present results from a Keck/DEIMOS survey to study satellite quenching in group environments at z ~ 0.8 within the Extended Groth Strip (EGS). We target 11 groups in the EGS with extended X-ray emission. We obtain high-quality spectroscopic redshifts for group member candidates, extending to depths over 1 order of magnitude fainter than existing DEEP2/DEEP3 spectroscopy. This depth enables the first spectroscopic measurement of the satellite quiescent fraction down to stellar masses of ~10 9.5 M ⊙ at this redshift. By combining an infall-based environmental quenching model, constrained by the observed quiescent fractions, with infall histories of simulated groups from the IllustrisTNG100-1-Dark simulation, we estimate environmental quenching timescales ( τ quench ) for the observed group population. At high stellar masses ( M ⋆ = 10 10.5 M ⊙ ) we find that {\tau }_{{\rm{quench}}}=2.4\begin{array}{c}+0.2\\ -0.2\end{array} Gyr, which is consistent with previous estimates at this epoch. At lower stellar masses ( M ⋆ = 10 9.5 M ⊙ ), we find that {\tau }_{{\rm{quench}}}=3.1\begin{array}{c}+0.5\\ -0.4\end{array} Gyr, which is shorter than prior estimates from photometry-based investigations. These timescales are consistent with satellite quenching via starvation, provided the hot gas envelope of infalling satellites is not stripped away. We find that the evolution in the quenching timescale between 0 < z <1 aligns with the evolution in the dynamical time of the host halo and the total cold gas depletion time. This suggests that the doubling of the quenching timescale in groups since z ~ 1 could be related to the dynamical evolution of groups or a decrease in quenching efficiency via starvation with decreasing redshift.}, archive = {J_ApJ}, author = {Devontae C. Baxter and Sean P. Fillingham and Alison L. Coil and Michael C. Cooper}, doi = {10.3847/1538-4357/ad9aa4}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {41}, shortjournal = {The Astrophys. J.}, title = {The importance of gas starvation in driving satellite quenching in galaxy groups at z ~ 0.8}, volume = {979}, year = {2025}, }
• (2025). Repeating partial tidal encounters of sun-like stars leading to their complete disruption. ApJ, 979(1), 40. (www)

  @article{ , abstract = {Stars grazing supermassive black holes on bound orbits may produce periodic flares over many passages, known as repeating partial tidal disruption events (TDEs). Here, we present 3D hydrodynamic simulations of Sun-like stars over multiple tidal encounters. The star is significantly restructured and becomes less concentrated as a result of mass loss and tidal heating. The vulnerability to mass loss depends sensitively on the stellar density structure, and the strong correlation between the fractional mass loss Δ M / M * and the ratio of the central and average density {\rho }_{{\rm{c}}}/\bar{\rho } , which was initially derived in disruption simulations of main-sequence stars, also applies for stars strongly reshaped by tides. Over multiple orbits, the star loses progressively more mass in each encounter and is doomed to a complete disruption. Throughout its lifetime, the star may produce numerous weak flares (depending on the initial impact parameter), followed by a couple of luminous flares whose brightness increases exponentially. Flux-limited surveys are heavily biased toward the brightest flares, which may appear similar to the flare produced by the same star undergoing a full disruption on its first tidal encounter. This places new challenges on constraining the intrinsic TDE rates, which need to take repeating TDEs into account. Other types of stars with different initial density structures (e.g., evolved stars with massive cores) follow distinct evolution tracks, which might explain the diversity of the long-term luminosity evolution seen in recently uncovered repeaters.}, archive = {J_ApJ}, author = {Chang Liu and Ricardo Yarza and Enrico Ramirez-Ruiz}, doi = {10.3847/1538-4357/ad9b0b}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {40}, shortjournal = {The Astrophys. J.}, title = {Repeating partial tidal encounters of sun-like stars leading to their complete disruption}, volume = {979}, year = {2025}, }
• (2025). Low-energy injection and nonthermal particle acceleration in relativistic magnetic turbulence. ApJ, 979(1), 39. (www)

  @article{ , abstract = {Relativistic magnetic turbulence has been proposed as a process for producing nonthermal particles in high-energy astrophysics. The particle energization may be contributed by both magnetic reconnection and turbulent fluctuations, but their interplay is poorly understood. It has been suggested that during magnetic reconnection the parallel electric field dominates the particle acceleration up to the lower bound of the power-law particle spectrum, but recent studies show that electric fields perpendicular to the magnetic field can play an important, if not dominant role. In this study, we carry out two-dimensional fully kinetic particle-in-cell simulations of magnetically dominated decaying turbulence in a relativistic pair plasma. For a fixed magnetization parameter σ 0 = 20, we find that the injection energy ε inj converges with increasing domain size to ε inj ≃ 10 m e c 2 . In contrast, the power-law index, the cut-off energy, and the power-law extent increase steadily with domain size. We trace a large number of particles and evaluate the contributions of the work done by the parallel ( W ∥ ) and perpendicular ( W ⊥ ) electric fields during both the injection phase and the postinjection phase. We find that during the injection phase, the W ⊥ contribution increases with domain size, suggesting that it may eventually dominate injection for a sufficiently large domain. In contrast, on average, both components contribute equally during the postinjection phase, insensitive to the domain size. For high energy ( ε ≫ ε inj ) particles, W ⊥ dominates the subsequent energization. These findings may improve our understanding of nonthermal particles and their emissions in astrophysical plasmas.}, archive = {J_ApJ}, author = {Divjyot Singh and Omar French and Fan Guo and Xiaocan Li}, doi = {10.3847/1538-4357/ad9b12}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {39}, shortjournal = {The Astrophys. J.}, title = {Low-energy injection and nonthermal particle acceleration in relativistic magnetic turbulence}, volume = {979}, year = {2025}, }
• (2025). Simultaneous multiband photometry of the early optical afterglow of GRB 240825A with mephisto. ApJ, 979(1), 38. (www)

  @article{ , abstract = {Gamma-ray bursts (GRBs) are the most luminous transients in the Universe. The interaction of the relativistic jet with the circumburst medium produces an afterglow and generates multiwavelength emission. In this work, we present simultaneous multiband photometry of GRB 240825A with the Multi-channel Photometric Survey Telescope (Mephisto) and analyze its temporal and spectral properties. The measurement began 128 s after the GRB trigger and continued until the fourth day, when the afterglow essentially diminished and the measured brightness was close to that of the host galaxy. Based on the multiband light curves in the uvgriz bands, we find that the optical flux density satisfies F ν ,obs ∝ t −1.34 ν −2.48 with a spectral index of 2.48, much larger than those of most other GRBs. To reconcile the measured much softer spectral energy distribution (SED) with that predicted by the standard afterglow model, an extra host-galaxy extinction of E B − V ∼ (0.37–0.57) mag is required. We interpreted this excess as arising from a dense circumburst medium. We further find that the SED of the optical afterglow hardened as the afterglow decayed and the color excess E B − V decreased ∼0.26 mag from 100 to 3000 s after the GRB trigger. Finally, we analyze the properties of the host galaxy of GRB 240825A based on data from the Sloan Digital Sky Survey, the Pan-STARRS survey, and the HSC-SSP survey. For a host redshift of z = 0.659, the stellar mass and star formation rate of the host galaxy are estimated to be \mathrm{log}({M}_{* }/{M}_{\odot })=10.{0}_{-0.3}^{+0.3} and \mathrm{log}({\rm{SFR}}/{M}_{\odot }{{\rm{yr}}}^{-1})=0.{6}_{-3.3}^{+0.8} , respectively, pointing to a gas-rich, star-forming, medium-size galaxy.}, archive = {J_ApJ}, author = {Yehao Cheng and Yu Pan and Yuan-Pei Yang and Jinghua Zhang and Guowang Du and Yuan Fang and Brajesh Kumar and Helong Guo and Xinzhong Er and Xinlei Chen and Chenxu Liu and Tao Wang and Zhenfei Qin and Yicheng Jin and Xingzhu Zou and Xuhui Han and Pinpin Zhang and Liping Xin and Chao Wu and Jianhui Lian and Xiangkun Liu and Xiaowei Liu}, doi = {10.3847/1538-4357/ad9ea1}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {38}, shortjournal = {The Astrophys. J.}, title = {Simultaneous multiband photometry of the early optical afterglow of GRB 240825A with mephisto}, volume = {979}, year = {2025}, }
• (2025). Dynamics of small, constant-size particles in a protoplanetary disk with an embedded protoplanet. ApJ, 979(1), 37. (www)

  @article{ , abstract = {Hydrodynamical simulations of protoplanetary disk dynamics are useful tools for understanding the formation of planetary systems, including our own. Approximations are necessary to make these simulations computationally tractable. A common assumption when simulating dust fluids is that of a constant Stokes number, a dimensionless number that characterizes the interaction between a particle and the surrounding gas. Constant Stokes number is not a good approximation in regions of the disk where the gas density changes significantly, such as near a planet-induced gap. In this paper, we relax the assumption of a constant Stokes number in the popular FARGO3D code using semianalytic equations for the drag force on dust particles, which enables an assumption of constant particle size instead. We explore the effect this change has on disk morphology and particle fluxes across the gap for both outward- and inward-drifting particles. The assumption of constant particle size, rather than constant Stokes number, is shown to make a significant difference in some cases, emphasizing the importance of the more accurate treatment.}, archive = {J_ApJ}, author = {Ellen M. Price and Eric Van Clepper and Fred J. Ciesla}, doi = {10.3847/1538-4357/ad9f35}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {37}, shortjournal = {The Astrophys. J.}, title = {Dynamics of small, constant-size particles in a protoplanetary disk with an embedded protoplanet}, volume = {979}, year = {2025}, }
• (2025). Star-forming nuclear clusters in dwarf galaxies mimicking active galactic nucleus signatures in the mid-infrared. ApJ, 979(1), 36. (www)

  @article{ , abstract = {Effectively finding and identifying active galactic nuclei (AGNs) in dwarf galaxies is an important step in studying black hole formation and evolution. In this work, we examine four mid-infrared (IR)-selected AGN candidates in dwarf galaxies with stellar masses between M ⋆ ~ 10 8 and 10 9 M ⊙ and find that the galaxies are host to nuclear star clusters (NSCs) that are notably rare in how young and massive they are. We perform photometric measurements on the central star clusters in our target galaxies using Hubble Space Telescope optical and near-IR imaging and compare their observed properties to models of stellar population evolution. We find that these galaxies are host to very massive (~10 7 M ⊙ ), extremely young (≲8 Myr), and dusty (0.6 ≲ A v ≲ 1.8) NSCs. Our results indicate that these galactic nuclei have ongoing star formation, are still at least partially obscured by clouds of gas and dust, and are most likely producing the extremely red AGN-like mid-IR colors. Moreover, prior work has shown that these galaxies do not exhibit X-ray or optical AGN signatures. Therefore, we recommend caution when using mid-IR color–color diagnostics for AGN selection in dwarf galaxies, since, as directly exemplified in this sample, they can be contaminated by massive star clusters with ongoing star formation.}, archive = {J_ApJ}, author = {Megan R. Sturm and Bayli Hayes and Amy E. Reines}, doi = {10.3847/1538-4357/ada02f}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {36}, shortjournal = {The Astrophys. J.}, title = {Star-forming nuclear clusters in dwarf galaxies mimicking active galactic nucleus signatures in the mid-infrared}, volume = {979}, year = {2025}, }
• (2025). PHAST. the panchromatic hubble andromeda southern treasury. i. ultraviolet and optical photometry of over 90 million stars in m31. ApJ, 979(1), 35. (www)

  @article{ , abstract = {The Panchromatic Hubble Andromeda Southern Treasury (PHAST) is a large 195-orbit Hubble Space Telescope program imaging ∼0.45 deg 2 of the southern half of M31's star-forming disk at optical and near-ultraviolet (NUV) wavelengths. The PHAST survey area extends the northern coverage of the Panchromatic Hubble Andromeda Treasury (PHAT) down to the southern half of M31, covering out to a radius of ∼13 kpc along the southern major axis and in total ∼two-thirds of M31's star-forming disk. This new legacy imaging yields stellar photometry of over 90 million resolved stars using the Advanced Camera for Surveys in the optical (F475W and F814W), and the Wide Field Camera 3 (WFC3) in the NUV (F275W and F336W). The photometry is derived using all overlapping exposures across all bands, and achieves a 50% completeness-limited depth of F475W ∼ 27.7 in the lowest surface density regions of the outer disk and F475W ∼ 26.0 in the most crowded, high surface brightness regions near M31's bulge. We provide extensive analysis of the data quality, including artificial star tests to quantify completeness, photometric uncertainties, and flux biases, all of which vary due to the background source density and the number of overlapping exposures. We also present seamless population maps of the entire M31 disk, which show relatively well-mixed distributions for stellar populations older than 1–2 Gyr, and highly structured distributions for younger populations. The combined PHAST + PHAT photometry catalog of ∼0.2 billion stars is the largest ever produced for equidistant sources and is available for public download by the community.}, archive = {J_ApJ}, author = {Zhuo Chen and Benjamin Williams and Dustin Lang and Andrew Dolphin and Meredith Durbin and Julianne J. Dalcanton and Adam Smercina and Léo Girardi and Claire E. Murray and Eric F. Bell and Martha L. Boyer and Richard D’Souza and Karoline Gilbert and Karl Gordon and Puragra Guhathakurta and Francois Hammer and L. Clifton Johnson and Tod R. Lauer and Margaret Lazzarini and Jeremiah W. Murphy and Ekta Patel and Amanda Quirk and Mariangelly Díaz Rodríguez and Julia Christine Roman-Duval and Robyn E. Sanderson and Anil Seth and Tobin M. Wainer and Daniel R. Weisz}, doi = {10.3847/1538-4357/ad7e2b}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {35}, shortjournal = {The Astrophys. J.}, title = {PHAST. the panchromatic hubble andromeda southern treasury. i. ultraviolet and optical photometry of over 90 million stars in m31}, volume = {979}, year = {2025}, }
• (2025). The theory of resonant cosmic ray–driven Instabilities—Growth and saturation of single modes. ApJ, 979(1), 34. (www)

  @article{ , abstract = {Cosmic-ray (CR) feedback is critical for galaxy formation as CRs drive galactic winds, regularize star formation in galaxies, and escape from active galactic nuclei to heat the cooling cores of galaxy clusters. The feedback strength of CRs depends on their coupling to the background plasma and, as such, on the effective CR transport speed. Traditionally, this has been hypothesized to depend on the balance between the wave growth of CR-driven instabilities and their damping. Here, we study the physics of CR-driven instabilities from first principles, starting from a gyrotropic distribution of CR ions that stream along a background magnetic field. We develop a theory of the underlying processes that organize the particles' orbits and in particular their gyrophases, which provides an intuitive physical picture of (i) wave growth as the CR gyrophases start to bunch up lopsidedly toward the local wave magnetic field, (ii) instability saturation as a result of CRs overtaking the wave and damping its amplitude without isotropizing CRs in the wave frame, and (iii) CR backreaction onto the unstable plasma waves as the CR gyrophases follow a pendulum motion around the wave magnetic field. Using our new fluid-particle-in-cell code fluid-SHARP, we validate our theory on the evolution and excitation of individual unstable modes, such as forward- and backward-propagating Alfvén and whistler waves. We show that these kinetic simulations support our theoretical considerations, thus potentially foreshadowing a revision of the theory of CR transport in galaxies and galaxy clusters.}, archive = {J_ApJ}, author = {Rouven Lemmerz and Mohamad Shalaby and Christoph Pfrommer and Timon Thomas}, doi = {10.3847/1538-4357/ad8eb3}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {34}, shortjournal = {The Astrophys. J.}, title = {The theory of resonant cosmic ray–driven Instabilities—Growth and saturation of single modes}, volume = {979}, year = {2025}, }
• (2025). Red stellar populations and dust extinction toward w3. ApJ, 979(1), 33. (www)

  @article{ , abstract = {We explore red stellar populations toward the W3 giant molecular cloud through the use of optical-to-infrared (IR) photometry and Gaia DR 3 data, simultaneously characterizing stellar content and properties of dust in the molecular medium. We use a Rayleigh–Jeans color excess method modified to de-redden stellar observations of both red giants (RGs) and OB stars, and construct an IR Hertzsprung–Russell diagram validated against the Besançon Galactic model. Taking advantage of the near-universal IR interstellar extinction law and precise Gaia measurements, we develop a method for obtaining the spectral classification, foreground extinction, and distance moduli of stars, validated by spectroscopically confirmed OB stars. We constrain the observed parallax and proper motion of OB stars in W3, demonstrating the importance of considering systematic effects in the parallax bias, and assign parallax- and proper-motion-based cloud membership to our stellar samples. While it has been assumed that all spectroscopic OB stars are inside the W3 cloud, we find evidence of seven background B stars and three potential runaway OB stars. The methods developed here, which are based on known stellar populations, enable us to identify 82 new OB candidates that are confidently within the cloud. We quantify several dust-to-dust empirical correlations, in particular the IR color excess E ( H − [4.5]) and the optical depth τ 1 of submillimeter dust emission at 1 THz using RGs behind W3, measuring a best fit of E(H-[4.5])=(1.07\pm 0.04)\times {10}^{3}\,{{\tau }_{1}}_{,{\rm{HOTT}}}+(0.00\pm 0.02)\,{\rm{mag}} .}, archive = {J_ApJ}, author = {J. L. Campbell and P. G. Martin and S. Song and M. Rahman and L. Einstein}, doi = {10.3847/1538-4357/ad8ebb}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {33}, shortjournal = {The Astrophys. J.}, title = {Red stellar populations and dust extinction toward w3}, volume = {979}, year = {2025}, }
• (2025). Implication of galaxy-scale negative feedback by one of the most powerful multiphase outflows in a hyperluminous infrared galaxy at intermediate redshift. ApJ, 979(1), 32. (www)

  @article{ , abstract = {Powerful galactic outflows driven by active galactic nuclei (AGNs) are commonly considered as one of the main mechanisms to regulate star formation in massive galaxies. Ultra- and hyperluminous IR galaxies (U/HyLIRGs) are thought to represent a transition phase of galaxies from a rapidly growing period to a quiescent status as gas is swept out by outflows, providing a laboratory in which to investigate outflows and their feedback effects on hosts. In this paper we report recent Gemini and Atacama Large Millimeter/submillimeter Array (ALMA) observations of a HyLIRG, J1126, at z = 0.46842, which has been identified with a puzzling coexistence of a fast ionized outflow (>2000 km s −1 ) and an intense starburst (star formation rate of 800 M ⊙ yr −1 ). The Gemini observation shows the fast ionized outflow is extended to several kiloparsecs with a mass-loss rate of 180 M ⊙ yr −1 . A massive molecular outflow with a high mass-loss rate (2500 M ⊙ yr −1 ) is revealed by ALMA. The multiphase outflows show large factors of momentum boost and loading of kinetic power, indicating a driving by the thermal pressure of a nuclear hot wind and/or the radiation pressure of a highly obscured AGN. In addition to ejection of kinetic energy, it is also found that the powerful outflow can induce an ionizing shock in the galaxy disk and enhance the excitation and dissociation of molecular gas. The powerful outflow probably results in an instantaneous negative feedback and shows potential to regulate host growth in the long term.}, archive = {J_ApJ}, author = {Xiaoyang Chen and Masayuki Akiyama and Kohei Ichikawa and Yoshiki Toba and Toshihiro Kawaguchi and Takuma Izumi and Toshiki Saito and Daisuke Iono and Masatoshi Imanishi and Kianhong Lee and Hiroshi Nagai and Hirofumi Noda and Abdurro’uf and Mitsuru Kokubo and Naoki Matsumoto}, doi = {10.3847/1538-4357/ad93ab}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {32}, shortjournal = {The Astrophys. J.}, title = {Implication of galaxy-scale negative feedback by one of the most powerful multiphase outflows in a hyperluminous infrared galaxy at intermediate redshift}, volume = {979}, year = {2025}, }
• (2025). Deconstructing the properties of solar super active region 13664 in the context of the historic geomagnetic storm of 2024 may 10–11. ApJ, 979(1), 31. (www)

  @article{ , abstract = {Active regions (ARs) are sites of strong magnetic fields on the solar surface whose size can be several times that of Earth. They spawn dynamic activity, sometimes resulting in severe space weather. Some ARs characterized by extraordinary magnetic properties and exhibiting extreme activity are termed as super active regions (SARs). Recently, solar AR 13664 produced 23 X-class flares and unleashed multiple coronal mass ejections, which triggered a severe geomagnetic storm during 2024 May 10–11—the strongest storm on record since 2003. Here, we put AR 13664 in historical context over the cumulative period of 1874 May–2024 June. We find that AR 13664 stands at the 99.95th percentile in the distribution of area over 1874 May–2024 June and at the 99.10th percentile in terms of flux content among all ARs over the period 1996 April–2024 June. Our analysis indicates that five of its magnetic properties rank at the 100.00th percentile among all ARs observed during 2010 May–2024 June by the Solar Dynamic Observatory. A total of 16 magnetic properties of AR 13664 are ranked higher than the 99.00th percentile when compared to other ARs recorded in Space-weather Helioseismic Magnetic Imager Active Region Patch data series, which includes all well-established flare relevant parameters. Furthermore, we demonstrate that AR 13664 reached its most dynamic flare productive state following a rapid rate of rise of its flare-relevant parameters and that the X-class flares were more frequent near their peak values. Our analyses establish AR 13644 to be an SAR and provide a paradigm for investigating their flare-relevant physical characteristics.}, archive = {J_ApJ}, author = {Priyansh Jaswal and Suvadip Sinha and Dibyendu Nandy}, doi = {10.3847/1538-4357/ad960b}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {31}, shortjournal = {The Astrophys. J.}, title = {Deconstructing the properties of solar super active region 13664 in the context of the historic geomagnetic storm of 2024 may 10–11}, volume = {979}, year = {2025}, }
• (2025). Exploring simple-population and multiple-population globular clusters in the outer galactic halo using the hubble space telescope. ApJ, 979(1), 30. (www)

  @article{ , abstract = {The pseudo two-color diagram, known as chromosome map (ChM), is a valuable tool for identifying globular clusters (GCs), which consist of single or multiple stellar populations (MPs). Recent surveys of Galactic GCs using ChMs have provided stringent observational constraints on the formation of GCs and their stellar populations. However, these surveys have primarily focused on GCs at moderate distances from the Galactic center and composed of MPs. In this paper, we present the first detailed study of the stellar composition of four GCs in the outer halo of the Milky Way: Arp 2, Ruprecht 106, Terzan 7, and Terzan 8. Our analysis is based on high-precision photometry obtained from images collected with the Hubble Space Telescope in the F275W, F336W, F438W, F606W, and F814W bands. We find that Ruprecht 106 and Terzan 7 are composed solely of a single stellar population, whereas Arp 2 and Terzan 8 host both first- and second-population stars. In these clusters, the second population comprises about half and one-third of the total number of GC stars, respectively. The results from this paper and the literature suggest that the threshold in the initial GC mass, if present, should be smaller than approximately 10 5 M ⊙ . The first-population stars of Arp 2 and Terzan 8, along with the stars of the simple-population GCs Ruprecht 106 and Terzan 7, exhibit intrinsic F275W – F814W color spreads, likely indicative of [Fe/H] variations of approximately 0.05–0.30 dex. This suggests that star-to-star metallicity variations are a common feature of star clusters, regardless of the presence of MPs.}, archive = {J_ApJ}, author = {E. P. Lagioia and A. P. Milone and M. V. Legnardi and G. Cordoni and E. Dondoglio and A. Renzini and M. Tailo and T. Ziliotto and M. Carlos and S. Jang and A. F. Marino and A. Mohandasan and J. Qi and G. Rangwal and E. Bortolan and F. Muratore}, doi = {10.3847/1538-4357/ad98ee}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {30}, shortjournal = {The Astrophys. J.}, title = {Exploring simple-population and multiple-population globular clusters in the outer galactic halo using the hubble space telescope}, volume = {979}, year = {2025}, }
• (2025). Disk-locking regulates stellar rotation in young clusters: Insights from NGC 2264. ApJ, 979(1), 29. (www)

  @article{ , abstract = {Many young clusters possess extended main sequences, a phenomenon commonly ascribed to stellar rotation. However, the mechanism behind their very wide stellar rotation distributions remains unclear. A proposed explanation is that magnetic star–disk interaction can regulate stellar rotation, i.e., protostars with longer disk lifetimes will eventually evolve into slow rotators, and vice versa. To examine this hypothesis, we took the star-forming region NGC 2264, as a test bed. We have studied its high-mass pre-main-sequence and zero-age main-sequence (ZAMS) stars. We find that, on average, diskless pre-main-sequence stars rotate faster than their disk-bearing counterparts. The stellar rotation distribution of the ZAMS stars is similar to evolved young clusters. We conclude that disk-locking may play a crucial role in the rotational velocity distribution of intermediate-mass early-type stars. We suggest that the observed wide stellar rotation distributions in many young clusters can occur in their early stages.}, archive = {J_ApJ}, author = {Yutian Bu and Chenyu He and Min Fang and Chengyuan Li}, doi = {10.3847/1538-4357/ad98fb}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {29}, shortjournal = {The Astrophys. J.}, title = {Disk-locking regulates stellar rotation in young clusters: Insights from NGC 2264}, volume = {979}, year = {2025}, }
• (2025). Nebular and nonthermal radio emissions for young stellar populations with PARSEC v1.2s. ApJ, 979(1), 28. (www)

  @article{ , abstract = {In this paper, we compute, by means of the recently and thoroughly updated PARSE v1.2 s database of stellar nonrotating evolutionary tracks, the integrated stellar spectra, the ionizing photon budget, and the supernovae rates of young simple stellar populations (SSPs), for five metallicities between 0.0001 and 0.02 and four choices of stellar initial mass function (IMF) upper mass limits between 40 M ⊙ and 350 M ⊙ . Using the photo-ionization code CLOUDY , we compute, at this same range of metallicities and limits, the intensities of some selected recombination and collisionally excited lines as a function of the age of the SSP. We account for the electron temperature dependence on IMF upper mass limit and metallicity while computing the thermal radio emission component, and also accounted for recent advances in core-collapse supernova explosion models while computing the nonthermal radio emission component. We self-consistently add the emission lines, nebular continuum, and nonthermal radio emission to the original SSP integrated photospheric spectra. Finally, from the resulting new suite of SSPs, we provide a consistent set of analytical relations between star formation rate (SFR) and ultraviolet, optical, and thermal radio luminosities that can be used to convert attenuation-corrected and dust-unaffected luminosities to SFR estimates. In a forthcoming paper, we will use our new SSP libraries as input to the state-of-the-art radiative transfer model GRA phites and SIL icates to test the overall performance of these SSPs in reproducing the observed spectral energy distribution of young star-forming galaxies.}, archive = {J_ApJ}, author = {Ikechukwu A. Obi and Pius N. Okeke and Bonaventure I. Okere}, doi = {10.3847/1538-4357/ad9901}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {28}, shortjournal = {The Astrophys. J.}, title = {Nebular and nonthermal radio emissions for young stellar populations with PARSEC v1.2s}, volume = {979}, year = {2025}, }
• (2025). Photospheric swirls in a quiet-sun region. ApJ, 979(1), 27. (www)

  @article{ , abstract = {Swirl-shaped flow structures have been observed throughout the solar atmosphere, in both emission and absorption, at different altitudes and locations, and are believed to be associated with magnetic structures. However, the distribution patterns of such swirls, especially their spatial positions, remain unclear. Using the Automated Swirl Detection Algorithm, we identified swirls from the high-resolution photospheric observations, centered on Fe i 630.25 nm, of a quiet region near the Sun's central meridian by the Swedish 1-m Solar Telescope. Via a detailed study of the locations of the detected small-scale swirls with an average radius of  ~300 km, we found that most of them are located in lanes between mesogranules (which have an average diameter of  ~5.4 Mm) instead of the commonly believed intergranular lanes. The squared rotation, expansion/contraction and vector speeds, and proxy kinetic energy are all found to follow Gaussian distributions. Their rotation speed, expansion/contraction speed, and circulation are positively correlated with their radius. All these results suggest that photospheric swirls at different scales and locations across the observational 56 \mathop{.}\limits^{\unicode{x02033}} 5 × 57 \mathop{.}\limits^{\unicode{x02033}} 5 field of view could share the same triggering mechanism at preferred spatial and energy scales. A comparison with our previous work suggests that the number of photospheric swirls is positively correlated with the number of local magnetic concentrations, stressing again the close relation between swirls and local magnetic concentrations: the number of swirls should positively correlate with the number and strength of local magnetic concentrations.}, archive = {J_ApJ}, author = {Quan Xie and Jiajia Liu and Chris J. Nelson and Robert Erdélyi and Yuming Wang}, doi = {10.3847/1538-4357/ad99d4}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {27}, shortjournal = {The Astrophys. J.}, title = {Photospheric swirls in a quiet-sun region}, volume = {979}, year = {2025}, }
• (2025). Ionized gas outflows in the galaxy and mass assembly (GAMA) survey: Signatures of AGN feedback in low-mass galaxies. ApJ, 979(1), 26. (www)

  @article{ , abstract = {We present a sample of 398 galaxies with ionized gas outflow signatures in their spectra from the Galaxy and Mass Assembly Survey Data Release 4, including 45 low-mass galaxies with stellar masses M * < 10 10 M ⊙ . We assemble our sample by systematically searching for the presence of a second velocity component in the [O iii ] λλ 4959, 5007 doublet emission line in 39,612 galaxies with redshifts z < 0.3. The host galaxies are classified using the Baldwin–Phillips–Terlevich diagram, with ~89% identified as active galactic nuclei (AGNs) and composites and 11% as star-forming (SF) galaxies. The outflows are typically faster in AGNs with a median velocity of 936 km s −1 compared to 655 km s −1 in the SF objects. Of particular interest are the 45 galaxies in the low-mass range, of which a third are classified as AGNs/composites. The outflows from the low-mass AGNs are also faster and more blueshifted compared to those in the low-mass SF galaxies. This indicates that black hole outflows can affect host galaxies in the low-mass range and that AGN feedback in galaxies with M * < 10 10 M ⊙ should be considered in galaxy evolution models.}, archive = {J_ApJ}, author = {Sheyda Salehirad and Amy E. Reines and Mallory Molina}, doi = {10.3847/1538-4357/ad9a57}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {26}, shortjournal = {The Astrophys. J.}, title = {Ionized gas outflows in the galaxy and mass assembly (GAMA) survey: Signatures of AGN feedback in low-mass galaxies}, volume = {979}, year = {2025}, }
• (2025). A visibility-based angular bispectrum estimator for radio-interferometric data. ApJ, 979(1), 25. (www)

  @article{ , abstract = {Considering radio-interferometric observations, we present a fast and efficient estimator to compute the binned angular bispectrum (ABS) from gridded visibility data. The estimator makes use of Fast Fourier Transform techniques to compute the ABS covering all possible triangle shapes and sizes. Here, we present the formalism of the estimator and validate it using simulated visibility data for the Murchison Widefield Array observations at ν = 154.25 MHz. We find that our estimator is able to faithfully recover the ABS of the simulated sky signal with  ≈10%–15% accuracy for a wide variety of triangle shapes and sizes across the range of angular multipoles 46 ≤ ℓ ≤ 1320. In future work, we plan to apply this to actual data and also generalize it to estimate the three-dimensional redshifted 21 cm bispectrum.}, archive = {J_ApJ}, author = {Sukhdeep Singh Gill and Somnath Bharadwaj and Sk. Saiyad Ali and Khandakar Md Asif Elahi}, doi = {10.3847/1538-4357/ad9b20}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {25}, shortjournal = {The Astrophys. J.}, title = {A visibility-based angular bispectrum estimator for radio-interferometric data}, volume = {979}, year = {2025}, }
• (2025). Predictions of dust continuum emission from a potential circumplanetary disk: A case study of the planet candidate AB aurigae b. ApJ, 979(1), 24. (www)

  @article{ , abstract = {Gas-accreting planets embedded in protoplanetary disks are expected to show dust thermal emission from their circumplanetary disks (CPDs). However, a recently reported gas-accreting planet candidate, AB Aurigae b, has not been detected in (sub)millimeter continuum observations. We calculate the evolution of dust in the potential CPD of AB Aurigae b and predict its thermal emission at 1.3 mm wavelength as a case study, where the obtained features may also be applied to other gas-accreting planets. We find that the expected flux density from the CPD is lower than the 3 σ level of the previous continuum observation by the Atacama Large Millimeter/submillimeter Array with broad ranges of parameters, consistent with a nondetection. However, the expected planet mass and gas accretion rate are higher if the reduction of the observed near-infrared continuum and H α line emission due to the extinction by small grains is considered, resulting in higher flux density of the dust emission from the CPD at (sub)millimeter wavelengths. We find that the corrected predictions of the dust emission are stronger than the 3 σ level of the previous observation with the typical dust-to-gas mass ratio of the inflow to the CPD. This result suggests that the dust supply to the vicinity of AB Aurigae b is small if the planet candidate is not the scattered light of the star but is a planet and has a CPD. Future continuum observations at shorter wavelengths are required to obtain more robust clues to the question of whether the candidate is a planet or not.}, archive = {J_ApJ}, author = {Yuhito Shibaike and Jun Hashimoto and Ruobing Dong and Christoph Mordasini and Misato Fukagawa and Takayuki Muto}, doi = {10.3847/1538-4357/ad9b21}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {24}, shortjournal = {The Astrophys. J.}, title = {Predictions of dust continuum emission from a potential circumplanetary disk: A case study of the planet candidate AB aurigae b}, volume = {979}, year = {2025}, }
• (2025). Prospects for gamma-ray emission from magnetar regions in CTAO observations. ApJ, 979(1), 23. (www)

  @article{ , abstract = {Recent multiwavelength observations have highlighted magnetars as significant sources of cosmic rays, particularly through their gamma-ray emissions. This study examines three magnetar regions—CXOU J171405.7–31031, Swift J1834−0846, and SGR 1806−20—known for emitting detectable electromagnetic signals. We assess the detectability of these regions using the upcoming Cherenkov Telescope Array Observatory (CTAO) by conducting an ON/OFF spectral analysis and compare the expected results with existing observations. Our findings indicate that CTAO will detect gamma-ray emissions from these three magnetar regions with significantly reduced emission flux errors compared to current instruments. In particular, the study shows that the CXOUJ1714−3810 and SwiftJ1834−0846 magnetar regions can be observed by the full southern and northern CTAO arrays in just 5 hr of observation, with mean significances above 10 σ and 30 σ , respectively. This paper discusses the regions analyzed, presents key results, and concludes with insights drawn from the study.}, archive = {J_ApJ}, author = {M. F. Sousa and R. Costa and Jaziel G. Coelho and R. C. Dos Anjos}, doi = {10.3847/1538-4357/ad9b23}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {23}, shortjournal = {The Astrophys. J.}, title = {Prospects for gamma-ray emission from magnetar regions in CTAO observations}, volume = {979}, year = {2025}, }
• (2025). Type IV-like solar radio burst consisting of a series of short-time bursts observed by PSP. ApJ, 979(1), 22. (www)

  @article{ , abstract = {Solar and interplanetary radio bursts can reflect the existence and motion of energetic electrons and are therefore a kind of vital phenomenon in solar activities. The present study reported a solar radio storm observed by the Parker Solar Probe (PSP) in its eighth orbital encounter phase, and it lasted about 20 hr in a frequency range of 0.5–15 MHz, called the type IV-like burst. It consists of a series of numerous short-time (ST) bursts with the central frequency drifting slowly from  ~5 to  ~1 MHz, and each individual ST burst appears at a much faster frequency drifting rate and has a typical frequency range of a few MHz and a short duration of about 1–4 minutes. Based on the empirical models of the solar atmosphere adopted commonly, combining the in situ measurement by PSP, we analyzed and compared some possible mechanisms for the generation of these small-scale ST bursts and proposed that they were generated probably by a group of solitary kinetic Alfvén waves (SKAWs) in a magnetic loop accompanying coronal mass ejection and slowly moving outward, in which the frequency drifting of individual ST burst is caused by the SKAW's propagation and the central frequency drifting may be attributed to the motion of the magnetic loop.}, archive = {J_ApJ}, author = {Bing Ma and Ling Chen and Dejin Wu and Zongjun Ning and Marc Pulupa and Stuart D. Bale}, doi = {10.3847/1538-4357/ad9b7e}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {22}, shortjournal = {The Astrophys. J.}, title = {Type IV-like solar radio burst consisting of a series of short-time bursts observed by PSP}, volume = {979}, year = {2025}, }
• (2025). Epsilon canis majoris: The brightest extreme-ultraviolet source with surprisingly low interstellar absorption. ApJ, 979(1), 21. (www)

  @article{ , abstract = {The B2 star Epsilon Canis Majoris ( CMa), at parallax distance d = 124 ± 2 pc, dominates the H i photoionization of the Local Interstellar Cloud. At its closer parallax distance compared to previous estimates, CMa has a 0.9 mag fainter absolute magnitude M V = −3.97 ± 0.04. We combine measurements of distance with the integrated flux f = (41.5 ± 3.3) × 10 −6 erg cm −2 s −1 and angular diameter θ d = 0.80 ± 0.05 mas to produce a consistent set of stellar parameters: radius R = 10.7 ± 0.7 R ⊙ , mass M = 13.1 ± 2.3 M ⊙ , gravity \mathrm{log}g=3.50\pm 0.05 , effective temperature T eff ≈ 21,000 K, and luminosity L ≈ 20,000 L ⊙ . These parameters place CMa outside the β Cephei instability strip, consistent with its observed lack of pulsations. The observed extreme-ultraviolet spectrum yields a hydrogen photoionization rate Γ HI ≈ 10 −15 s −1 (at Earth). The total flux decrement factor at the Lyman limit (Δ LL = 5000 ± 500) is a combination of attenuation in the stellar atmosphere (Δ star = 110 ± 10) and interstellar medium (Δ ISM = 45 ± 5) with optical depth τ LL = 3.8 ± 0.1. After correcting for interstellar H i column density N HI = (6 ± 1) × 10 17 cm −2 , we find a stellar LyC photon flux Φ LyC ≈ 3000 cm −2 s −1 and ionizing luminosity Q LyC = 10 45.7±0.3 photons s −1 . The photoionization rate Γ H ≈ (1–2) × 10 −14 s −1 at the cloud surface produces an ionization fraction (30%–40%) for total hydrogen density n H = 0.2 cm −3 . With its 27.3 ± 0.4 km s −1 heliocentric radial velocity and small proper motion, CMa passed within 9.3 ± 0.5 pc of the Sun 4.4 Myr ago, with a 180 times higher photoionization rate.}, archive = {J_ApJ}, author = {J. Michael Shull and Rachel M. Curran and Michael W. Topping}, doi = {10.3847/1538-4357/ad9b8b}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {21}, shortjournal = {The Astrophys. J.}, title = {Epsilon canis majoris: The brightest extreme-ultraviolet source with surprisingly low interstellar absorption}, volume = {979}, year = {2025}, }
• (2025). Transients by black hole formation from red supergiants: Impact of dense circumstellar matter. ApJ, 979(1), 20. (www)

  @article{ , abstract = {Failed supernovae (SNe), which are likely the main channel for forming stellar-mass black holes, are predicted to accompany mass ejections much weaker than typical core-collapse SNe. We conduct a grid of one-dimensional radiation hydrodynamical simulations to explore the emission of failed SNe from red supergiant progenitors, leveraging recent understanding of the weak explosion and the dense circumstellar matter (CSM) surrounding these stars. We find from these simulations and semianalytical modeling that diffusion in the CSM prolongs the early emission powered by shock breakout/cooling. The early emission has peak luminosities of ~10 7 –10 8 L ⊙ in optical and UV and durations of days to weeks. The presence of dense CSM aids in the detection of the early bright peak from these events via near-future wide-field surveys such as Rubin Observatory, ULTRASAT, and UVEX.}, archive = {J_ApJ}, author = {Daichi Tsuna and Xiaoshan Huang and Jim Fuller and Anthony L. Piro}, doi = {10.3847/1538-4357/ad9bad}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {20}, shortjournal = {The Astrophys. J.}, title = {Transients by black hole formation from red supergiants: Impact of dense circumstellar matter}, volume = {979}, year = {2025}, }
• (2025). Line list for the A2Π−X2Σ+ and the B2Σ+−X2Σ+ band systems of CaF. ApJ, 979(1), 19. (www)

  @article{ , abstract = {The spectral analysis of molecule-rich asymptotic giant branch (AGB) stars is challenging. Although other calcium and fluorine bearing molecules are observed in the microwave and in the visible spectrum of AGB stars, CaF has never been detected, despite favorable chemical equilibrium predictions. Yet, measuring the CaF abundance could give more insight into the fluorine budget of AGB stars and allow better simulation of stellar spectra. In this work, we present an analysis of the visible spectrum of CaF obtained with a Fourier transform spectrometer. CaF A 2 Π− X 2 Σ + and B 2 Σ + − X 2 Σ + band systems were excited with a hollow cathode discharge. Using previous fluorescence spectroscopy measurements, highly accurate ground state constants, and reasonable extrapolation schemes, the strongest features of CaF in the visible spectrum can be accurately modeled for both band systems. Spectroscopic constants are determined for A 2 Π with v ≤ 16 and for B 2 Σ + with v ≤ 20. Ab initio transition dipole moment curves of both transitions were calculated and scaled, and we provide a line list with Einstein A coefficients and oscillator strengths. This line list can be used to simulate spectra of CaF at temperatures and pressures relevant to astrophysical environments.}, archive = {J_ApJ}, author = {Léo Lavy and Peter F Bernath and Adam Pastorek}, doi = {10.3847/1538-4357/ad9c7a}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {19}, shortjournal = {The Astrophys. J.}, title = {Line list for the A2Π−X2Σ+ and the B2Σ+−X2Σ+ band systems of CaF}, volume = {979}, year = {2025}, }
• (2025). The S4G-WISE view of global star formation in the nearby universe. ApJ, 979(1), 18. (www)

  @article{ , abstract = {In this work, we present source-tailored Wide-field Infrared Survey Explorer (WISE) mid-infrared photometry (at 3.4, 4.6, 12, and 23 μ m) of 2812 galaxies in the extended Spitzer Survey of Stellar Structure in Galaxies sample, and characterize the mid-infrared colors and dust properties of this legacy nearby galaxy data set. Informed by the relative emission between W3 (12 μ m) and W4 (23 μ m), we rederive star formation rate (SFR) scaling relations calibrated to L TIR , which results in improved agreement between the two tracers. By inverse–variance weighting the W3 and W4-derived SFRs, we generate a combined mid-infrared SFR that is a broadly robust measure of star formation activity in dusty, star-forming galaxies in the nearby Universe. In addition, we investigate the use of a W3-derived dust density metric, Σ 12 μ m ( L ⊙ /kpc 2 ), to estimate the SFR deficit of low mass, low dust galaxies. This is achieved by combining WISE with existing Galaxy Evolution Explorer ultraviolet (UV) photometry, which we further use to explore the relationship between dust and UV emission as a function of morphology. Finally, we use our derived SFR prescriptions to examine the location of galaxies in the log SFR–log M stellar plane, as a function of morphological type, which underscores the complexity of dust-derived properties seen in galaxies of progressively earlier type.}, archive = {J_ApJ}, author = {M. E. Cluver and T. H. Jarrett and D. A. Dale and J.-D. T. Smith and M. J. I. Brown and W. van Kempen and E. Lengerer and R. Incoll and C. Davey and R. Holloway and J. Cameron and K. Sheth}, doi = {10.3847/1538-4357/ad891b}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {18}, shortjournal = {The Astrophys. J.}, title = {The S4G-WISE view of global star formation in the nearby universe}, volume = {979}, year = {2025}, }
• (2025). ALMA survey of orion planck galactic cold clumps (ALMASOP): Nested morphological and kinematic structures of outflows revealed in SiO and CO emission. ApJ, 979(1), 17. (www)

  @article{ , abstract = {The Atacama Large Millimeter/submillimeter Array Survey of Orion Planck Galactic Cold Clumps (ALMASOP) reveals complex nested morphological and kinematic features of molecular outflows through the CO ( J = 2−1) and SiO ( J = 5−4) emission. We characterize the jet and outflow kinematics of the ALMASOP sample in four representative sources (HOPS 10, 315, 358, and G203.21-11.20W2) through channel maps and position–velocity diagrams (PVDs) parallel and transverse to the outflow axes. The combined CO and SiO emission exhibits the coexistence of the conventional extremely high-velocity jets and shell-like low-velocity cavity walls and new features. More complex, nested bubble-like and filamentary structures in the images and channel maps, triangle-shaped regions near the base of the parallel PVDs, and regions composed of rhombus/oval shapes in the transverse PVDs are also evident. Such features find natural explanations within the bubble structure of the unified model of jet, wind, and ambient medium. The reverse shock cavity is revealed on the PVD base regions, and other features naturally arise within the dynamic postshock region of magnetic interaction. The finer nested shells observed within the compressed wind region reveal previously unnoticed shocked emission between the jet and the conventional large cavity walls. These pseudopulse-produced filamentary features connect to the jetlike knotty blobs, creating an impression of episodicity in mass ejection. SiO emission is enhanced downstream of the reverse shock boundary, with jetlike excitation conditions. Combined, these observed features reveal the extended structures induced by the magnetic interplay between a jet-bearing magnetized wide-angle wind and its ambient magnetized surrounding medium.}, archive = {J_ApJ}, author = {Chun-Fan Liu and Hsien Shang and Doug Johnstone and Tsung-Han Ai and Tsz Ming Lee and Ruben Krasnopolsky and Naomi Hirano and Somnath Dutta and Shih-Ying Hsu and Jesús Alejandro López-Vázquez and Sheng-Yuan Liu and Tie Liu and Ken’ichi Tatematsu and Qizhou Zhang and Mark G. Rawlings and David Eden and Zhiyuan Ren and Patricio Sanhueza and Woojin Kwon and Chang Won Lee and Yi-Jehng Kuan and Somdeb Bandopadhyay and Miikka S. Väisälä and Chin-Fei Lee and Indrani Das}, doi = {10.3847/1538-4357/ad9275}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {17}, shortjournal = {The Astrophys. J.}, title = {ALMA survey of orion planck galactic cold clumps (ALMASOP): Nested morphological and kinematic structures of outflows revealed in SiO and CO emission}, volume = {979}, year = {2025}, }
• (2025). PS1-11aop: Probing the mass-loss history of a luminous interacting supernova prior to its final eruption with multiwavelength observations. ApJ, 979(1), 16. (www)

  @article{ , abstract = {Luminous interacting supernovae (SNe) are a class of stellar explosions whose progenitors underwent vigorous mass loss in the years prior to core collapse. While the mechanism by which this material is ejected is still debated, obtaining the full density profile of the circumstellar medium (CSM) could reveal more about this process. Here, we present an extensive multiwavelength study of PS1-11aop, a luminous and slowly declining Type IIn SNe discovered by the Pan-STARRS Medium Deep Survey. PS1-11aop had a peak r -band magnitude of −20.5 mag, a total radiated energy >8 × 10 50 erg, and it exploded near the center of a star-forming galaxy with super-solar metallicity. We obtained multiple detections at the location of PS1-11aop in the radio and X-ray bands between 4 and 10 yr post-explosion, and if due to the supernova (SN), it is one of the most luminous radio SNe identified to date. Taken together, the multiwavelength properties of PS1-11aop are consistent with a CSM density profile with multiple zones. The early optical emission is consistent with the SN blastwave interacting with a dense and confined CSM shell, which contains multiple solar masses of material that was likely ejected in the final <10–100 yr prior to the explosion, (∼0.05−1.0 M ⊙ yr −1 at radii of ≲10 16 cm). The radio observations, on the other hand, are consistent with a sparser environment (≲2 × 10 −3 M ⊙ yr −1 at radii of ∼0.5–1 × 10 17 cm)—thus probing the history of the progenitor star prior to its final mass-loss episode.}, archive = {J_ApJ}, author = {Adaeze L. Ibik and Maria R. Drout and Raffaella Margutti and David Matthews and V. Ashley Villar and Edo Berger and Ryan Chornock and Kate D. Alexander and Tarraneh Eftekhari and Tanmoy Laskar and Ragnhild Lunnan and Ryan J. Foley and David Jones and Dan Milisavljevic and Armin Rest and Daniel Scolnic and Peter K. G. Williams}, doi = {10.3847/1538-4357/ad9336}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {16}, shortjournal = {The Astrophys. J.}, title = {PS1-11aop: Probing the mass-loss history of a luminous interacting supernova prior to its final eruption with multiwavelength observations}, volume = {979}, year = {2025}, }
• (2025). Blowing out the candle: How to quench galaxies at high Redshift—An ensemble of rapid starbursts, AGN feedback, and environment. ApJ, 979(1), 15. (www)

  @article{ , abstract = {Recent observations with JWST and the Atacama Large Millimeter/submillimeter Array have revealed extremely massive quiescent galaxies at redshifts of z = 3 and higher, indicating both rapid onset and quenching of star formation. Using the cosmological simulation suite Magneticum Pathfinder, we reproduce the observed number densities and stellar masses, with 36 quenched galaxies of stellar mass larger than 3 × 10 10 M ⊙ at z = 3.42. We find that these galaxies are quenched through a rapid burst of star formation and subsequent active galactic nucleus (AGN) feedback caused by a particularly isotropic collapse of surrounding gas, occurring on timescales of around 200 Myr or shorter. The resulting quenched galaxies host stellar components that are kinematically fast rotating and alpha-enhanced, while exhibiting a steeper metallicity and flatter age gradient compared to galaxies of similar stellar mass. The gas of the galaxies has been metal enriched and ejected. We find that quenched galaxies do not inhabit the densest nodes, but rather sit in local underdensities. We analyze observable metrics to predict future quenching at high redshifts, finding that on shorter timescales <500 Myr, the ratio M bh / M * is the best predictor, followed by the burstiness of the preceding star formation, t 50 – t 90 (time to go from 50% to 90% stellar mass). On longer timescales, >1 Gyr, the environment becomes the strongest predictor, followed by t 50 – t 90 , indicating that at high redshifts the consumption of old gas and lack of new gas are more relevant for long-term prevention of star formation than the presence of a massive AGN. We predict that relics of such high- z quenched galaxies should best be characterized by a strong alpha enhancement.}, archive = {J_ApJ}, author = {Lucas C. Kimmig and Rhea-Silvia Remus and Benjamin Seidel and Lucas M. Valenzuela and Klaus Dolag and Andreas Burkert}, doi = {10.3847/1538-4357/ad9472}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {15}, shortjournal = {The Astrophys. J.}, title = {Blowing out the candle: How to quench galaxies at high Redshift—An ensemble of rapid starbursts, AGN feedback, and environment}, volume = {979}, year = {2025}, }
• (2025). An indication of gas inflow in clumpy star-forming galaxies near z ∼ 1: Lower gas-phase metallicities in clumpy galaxies compared to nonclumpy galaxies. ApJ, 979(1), 14. (www)

  @article{ , abstract = {Despite the ubiquity of clumpy star-forming galaxies at high-redshift, the origin of clumps are still largely unconstrained due to the limited observations that can validate the mechanisms for clump formation. We postulate that if clumps form due to the accretion of metal-poor gas that leads to violent disk instability, clumpy galaxies should have lower gas-phase metallicities compared to nonclumpy galaxies. In this work, we obtain the near-infrared spectrum for 42 clumpy and nonclumpy star-forming galaxies of similar masses, star formation rates, and colors at z ≈ 0.7 using the Gemini Near-Infrared Spectrograph (GNIRS) and infer their gas-phase metallicity from the [N ii ] λ 6584 and H α line ratio. We find that clumpy galaxies have lower metallicities compared to nonclumpy galaxies, with an offset in the weighted average metallicity of 0.07 ± 0.02 dex. We also find an offset of 0.06 ± 0.02 dex between clumpy and nonclumpy galaxies in a comparable sample of 23 star-forming galaxies at z ≈ 1.5 using existing data from the FMOS-COSMOS survey. Similarly, lower [N ii ] λ 6584/H α ratios are typically found in galaxies that have more of their UV rest luminosity originating from clumps, suggesting that clumpier galaxies are more metal-poor. We also derive the intrinsic velocity dispersion and line-of-sight rotational velocity for galaxies from the GNIRS sample. The majority of galaxies have σ 0 / v c ≈ 0.2, with no significant difference between clumpy and nonclumpy galaxies. Our result indicates that clump formation may be related to the inflow of metal-poor gas; however, the process that forms them does not necessarily require significant, long-term kinematic instability in the disk.}, archive = {J_ApJ}, author = {Visal Sok and Adam Muzzin and Pascale Jablonka and Vivian Yun Yan Tan and Z. Cemile Marsan and Danilo Marchesini and Gillian Wilson and Leo Y. Alcorn}, doi = {10.3847/1538-4357/ad96bb}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {14}, shortjournal = {The Astrophys. J.}, title = {An indication of gas inflow in clumpy star-forming galaxies near z ∼ 1: Lower gas-phase metallicities in clumpy galaxies compared to nonclumpy galaxies}, volume = {979}, year = {2025}, }
• (2025). SN h0pe: The first measurement of h0 from a multiply imaged type ia supernova, discovered by JWST. ApJ, 979(1), 13. (www)

  @article{ , abstract = {The first James Webb Space Telescope (JWST) Near InfraRed Camera imaging in the field of the galaxy cluster PLCK G165.7+67.0 ( z = 0.35) uncovered a Type Ia supernova (SN Ia) at z = 1.78, called "SN H0pe." Three different images of this one SN were detected as a result of strong gravitational lensing, each one traversing a different path in spacetime, thereby inducing a relative delay in the arrival of each image. Follow-up JWST observations of all three SN images enabled photometric and rare spectroscopic measurements of the two relative time delays. Following strict blinding protocols which oversaw a live unblinding and regulated postunblinding changes, these two measured time delays were compared to the predictions of seven independently constructed cluster lens models to measure a value for the Hubble constant, H 0 =  71.8 + 9.2 − 8.1 km s −1 Mpc −1 . The range of admissible H 0 values predicted across the lens models limits further precision, reflecting the well-known degeneracies between lens model constraints and time delays. It has long been theorized that a way forward is to leverage a standard candle, but this has not been realized until now. For the first time, the lens models are evaluated by their agreement with the SN absolute magnifications, breaking degeneracies and producing our best estimate, H 0 = {75.7}_{-5.5}^{+8.1} km s −1 Mpc −1 . This is the first precise measurement of H 0 from a multiply imaged SN Ia and only the second from any multiply imaged SN.}, archive = {J_ApJ}, author = {Massimo Pascale and Brenda L. Frye and Justin D. R. Pierel and Wenlei Chen and Patrick L. Kelly and Seth H. Cohen and Rogier A. Windhorst and Adam G. Riess and Patrick S. Kamieneski and José M. Diego and Ashish K. Meena and Sangjun Cha and Masamune Oguri and Adi Zitrin and M. James Jee and Nicholas Foo and Reagen Leimbach and Anton M. Koekemoer and C. J. Conselice and Liang Dai and Ariel Goobar and Matthew R. Siebert and Lou Strolger and S. P. Willner}, doi = {10.3847/1538-4357/ad9928}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {13}, shortjournal = {The Astrophys. J.}, title = {SN h0pe: The first measurement of h0 from a multiply imaged type ia supernova, discovered by JWST}, volume = {979}, year = {2025}, }
• (2025). The optical extinction law depends on magnetic field orientation: The RV–ψ relation. ApJ, 979(1), 12. (www)

  @article{ , abstract = {For aspherical interstellar dust grains aligned with their short axes preferentially parallel to the local magnetic field, the amount of extinction per grain is larger when the magnetic field is along the line of sight and smaller when in the plane of the sky. To the extent that optical extinction arises from both aligned and unaligned grain populations with different extinction properties, changes in the magnetic field orientation induce changes in its wavelength dependence, parameterized by R V ≡ A V / E ( B − V ). We demonstrate that the measured total and polarized extinction curves of the diffuse Galactic interstellar medium imply R V varies from 3.21 when the magnetic field is along the line of sight ( ψ = 0) to R V = 3.05 when in the plane of the sky ( ψ = 90°). This effect could therefore account for much of the large-scale R V variation observed across the sky ( σ ( R V ) ≃ 0.2), particularly at high Galactic latitudes.}, archive = {J_ApJ}, author = {Brandon S. Hensley}, doi = {10.3847/1538-4357/ad9b9a}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {12}, shortjournal = {The Astrophys. J.}, title = {The optical extinction law depends on magnetic field orientation: The RV–ψ relation}, volume = {979}, year = {2025}, }
• (2025). Constraining the gamma-ray burst jet opening angle based on the very steep decay phase. ApJ, 979(1), 11. (www)

  @article{ , abstract = {Thanks to the rapid follow-up observations by the Swift X-Ray Telescope (XRT), a good part of gamma-ray bursts' (GRBs) high-latitude emission have been observed in the X-ray band. Some even show a dropdown decay after this period, which strongly indicates the edge of the jet is corresponding to the breaking time. This study constrains the jet opening angles of GRBs by analyzing the very steep decay phase in the early X-ray afterglow. Using data from Swift/XRT, we identified GRBs with significant breaks in their light curves and applied a broken power-law model to describe the decay phases. Assuming a spherical and isotropic emitting surface, we set constraints on the radiation radius ( R γ ) to estimate jet opening angles ( θ jet ) from the breaking time. Our results indicate that jet opening angles can be constrained, although they are sensitive to the assumed radiation radius. This approach provides yet another method for estimating GRB jet opening angles.}, archive = {J_ApJ}, author = {Qian Xu and Dong-Jie Liu and Yuan-Chuan Zou}, doi = {10.3847/1538-4357/ada032}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {11}, shortjournal = {The Astrophys. J.}, title = {Constraining the gamma-ray burst jet opening angle based on the very steep decay phase}, volume = {979}, year = {2025}, }
• (2025). Quadrupole moment of a magnetically confined mountain on an accreting neutron star in general relativity. ApJ, 979(1), 10. (www)

  @article{ , abstract = {General relativistic corrections are calculated for the quadrupole moment of a magnetically confined mountain on an accreting neutron star. The hydromagnetic structure of the mountain satisfies the general relativistic Grad–Shafranov equation supplemented by the flux-freezing condition of ideal magnetohydrodynamics, as in previous calculations of the magnetic dipole moment. It is found that the ellipticity, and hence the gravitational wave strain, are up to 12% greater than in the analogous Newtonian system. The direct contribution of the magnetic field to the nonaxisymmetric component of the stress-energy tensor is shown to be negligible in accreting systems such as low-mass X-ray binaries.}, archive = {J_ApJ}, author = {Pedro H. B. Rossetto and Jörg Frauendiener and Andrew Melatos}, doi = {10.3847/1538-4357/ada276}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {10}, shortjournal = {The Astrophys. J.}, title = {Quadrupole moment of a magnetically confined mountain on an accreting neutron star in general relativity}, volume = {979}, year = {2025}, }
• (2025). Gravitational-wave dark siren cosmology systematics from galaxy weighting. ApJ, 979(1), 9. (www)

  @article{ , abstract = {The detection of GW170817 and the measurement of its redshift from the associated electromagnetic counterpart provided the first gravitational-wave (GW) determination of the Hubble constant ( H 0 ), demonstrating the potential power of standard siren cosmology. In contrast to this "bright siren" approach, the "dark siren" approach can be utilized for GW sources in the absence of an electromagnetic counterpart: One considers all galaxies contained within the localization volume as potential hosts. When statistically averaging over the potential host galaxies, weighting them by physically motivated properties (e.g., tracing star formation or stellar mass) could improve convergence. Using mock galaxy catalogs, we explore the impact of these weightings on the measurement of H 0 . We find that incorrect weighting schemes can lead to significant biases due to two effects: the assumption of an incorrect galaxy redshift distribution, and preferentially weighting incorrect host galaxies during the inference. The magnitudes of these biases are influenced by the number of galaxies along each line of sight, the measurement uncertainty in the GW luminosity distance, and correlations in the parameter space of galaxies. We show that the bias may be overcome from improved localization constraints in future GW detectors, a strategic choice of priors or weighting prescription, and by restricting the analysis to a subset of high-signal-to-noise ratio events. We propose the use of hierarchical inference as a diagnostic of incorrectly weighted prescriptions. Such approaches can simultaneously infer the correct weighting scheme and the values of the cosmological parameters, thereby mitigating the bias in dark siren cosmology due to incorrect host-galaxy weighting.}, archive = {J_ApJ}, author = {Alexandra G. Hanselman and Aditya Vijaykumar and Maya Fishbach and Daniel E. Holz}, doi = {10.3847/1538-4357/ad9393}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {9}, shortjournal = {The Astrophys. J.}, title = {Gravitational-wave dark siren cosmology systematics from galaxy weighting}, volume = {979}, year = {2025}, }
• (2025). A cosmic ray acceleration mechanism based on background flow velocity inhomogeneities yielding power-law spectra. ApJ, 979(1), 8. (www)

  @article{ , abstract = {In astrophysics, one significant challenge lies in understanding the acceleration of cosmic rays, which leads to the occurrence of a power law. In this article, momentum transport generated by the combined effects of pitch-angle diffusion and background flow velocity inhomogeneities is proposed to obtain a cosmic rays acceleration mechanism, starting from the well-known focused transport equation describing particle diffusion and acceleration. The inhomogeneities of background flow velocity are ubiquitous in the astrophysical environment. The equation for the isotropic part of the distribution function of charged energetic particles is derived, and its solution is obtained, demonstrating the form of momentum power laws of cosmic rays. In addition, if it is assumed that cosmic rays penetrate compressive MHD waves or turbulence, for quasi-steady states, the spectral index δ of the momentum power law spectrum of cosmic rays is found to be in the range [−5, −3], which includes the observed power law indices of galactic cosmic rays. The results obtained in this article demonstrate that the mechanism proposed in this article, along with shock acceleration, may also contribute to the acceleration of galactic cosmic rays. Furthermore, when momentum convection effect and higher-order momentum derivative terms are considered, the indices of power laws should be smaller than −5. This may explain the power laws of solar energetic particle events.}, archive = {J_ApJ}, author = {J.-F. Wang and G. Qin}, doi = {10.3847/1538-4357/ad93a8}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {8}, shortjournal = {The Astrophys. J.}, title = {A cosmic ray acceleration mechanism based on background flow velocity inhomogeneities yielding power-law spectra}, volume = {979}, year = {2025}, }
• (2025). The effect of galaxy interactions on starbursts in milky way-mass galaxies in FIRE simulations. ApJ, 979(1), 7. (www)

  @article{ , abstract = {Simulations and observations suggest that galaxy interactions may enhance the star formation rate (SFR) in merging galaxies. One proposed mechanism is the torque exerted on the gas and stars in the larger galaxy by the smaller galaxy. We analyze the interaction torques and star formation activity on six galaxies from the FIRE-2 simulation suite with masses comparable to the Milky Way galaxy at redshift z = 0. We trace the halos from z = 3.6 to z = 0, calculating the torque exerted by the nearby galaxies on the gas in the central galaxy. We calculate the correlation between the torque and the SFR across the simulations for various mass ratios. For near-equal-stellar-mass-ratio interactions in the galaxy sample, occurring between z = 1.2−3.6, there is a positive and statistically significant correlation between the torque from nearby galaxies on the gas of the central galaxies and the SFR. For all other samples, no statistically significant correlation is found between the torque and the SFR. Our analysis shows that some, but not all, major interactions cause starbursts in the simulated Milky Way-mass galaxies, and that most starbursts are not caused by galaxy interactions. The transition from "bursty" at high redshift ( z ≳ 1) to "steady" star formation state at later times is independent of the interaction history of the galaxies, and most of the interactions do not leave significant imprints on the overall trend of the star formation history of the galaxies.}, archive = {J_ApJ}, author = {Fei Li and Mubdi Rahman and Norman Murray and Dušan Kereš and Andrew Wetzel and Claude-André Faucher-Giguère and Philip F. Hopkins and Jorge Moreno}, doi = {10.3847/1538-4357/ad94ef}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {7}, shortjournal = {The Astrophys. J.}, title = {The effect of galaxy interactions on starbursts in milky way-mass galaxies in FIRE simulations}, volume = {979}, year = {2025}, }
• (2025). On the existence of long-period decayless oscillations in short active region loops. ApJ, 979(1), 6. (www)

  @article{ , abstract = {Decayless kink oscillations, characterized by their lack of decay in amplitude, have been detected in coronal loops of varying scales in active regions, the quiet Sun, and coronal holes. Short-period (<50 s) decayless oscillations have been detected in short loops (< 50 Mm) within active regions. Nevertheless, long-period decayless oscillations in these loops remain relatively unexplored and crucial for understanding the wave modes and excitation mechanisms of decayless oscillations. We present the statistical analysis of decayless oscillations from two active regions observed by the Extreme Ultraviolet Imager onboard Solar Orbiter. The average loop length and period of the detected oscillations are 19 Mm and 151 s, respectively. We find 82 long-period and 23 short-period oscillations in these loops. We do not obtain a significant correlation between loop length and period. We discuss the possibility of different wave modes in short loops, although standing waves cannot be excluded from possible wave modes. Furthermore, a different branch exists for active region short loops in the loop length versus period relation, similar to decayless waves in short loops in the quiet Sun and coronal holes. The magnetic fields derived from MHD seismology, based on standing kink modes, show lower values for multiple oscillations compared to previous estimates for long loops in active regions. Additionally, the comparison of period distributions in short loops across different coronal regions indicates that different excitation mechanisms may trigger short-period kink oscillations in active regions compared to the quiet Sun and coronal holes.}, archive = {J_ApJ}, author = {Arpit Kumar Shrivastav and Vaibhav Pant and Rohan Kumar and David Berghmans and Tom Van Doorsselaere and Dipankar Banerjee and Elena Petrova and Daye Lim}, doi = {10.3847/1538-4357/ad95fb}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {6}, shortjournal = {The Astrophys. J.}, title = {On the existence of long-period decayless oscillations in short active region loops}, volume = {979}, year = {2025}, }
• (2025). Closing the stellar labels gap: Stellar label independent evidence for [α/M] information in gaia BP/RP spectra. ApJ, 979(1), 5. (www)

  @article{ , abstract = {Data-driven models for stellar spectra that depend on stellar labels suffer from label systematics which decrease model performance: the stellar labels gap. To close the stellar labels gap, we present a stellar label independent model for Gaia BP/RP spectra. We develop a novel implementation of a variational auto-encoder, which learns to generate an XP spectrum and accompanying scatter without relying on stellar labels. We demonstrate that our model achieves competitive XP spectra reconstructions in comparison to stellar label dependent models. We find that our model learns stellar properties directly from the data itself. We then apply our model to XP/APOGEE giant stars to study the [ α / M ] information in Gaia XP. We provide strong evidence that the XP spectra contain meaningful [ α / M ] information by demonstrating that our model learns the α -bimodality, without relying on stellar label correlations for stars with T eff < 5000 K, while also being sensitive to the anomalous abundances of Gaia-Enceladus stars. We have publicly released our trained model, codebase and data. Importantly, our stellar label independent model can be implemented for any and all XP spectra because our model's performance scales with training object density, not training label density.}, archive = {J_ApJ}, author = {Alexander Laroche and Joshua S. Speagle}, doi = {10.3847/1538-4357/ad9607}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {5}, shortjournal = {The Astrophys. J.}, title = {Closing the stellar labels gap: Stellar label independent evidence for [α/M] information in gaia BP/RP spectra}, volume = {979}, year = {2025}, }
• (2025). A uGMRT and MeerKAT study of radio relics in the low-mass merging cluster PSZ2 g200.95−28.16. ApJ, 979(1), 4. (www)

  @article{ , abstract = {Diffuse radio sources known as radio relics are direct tracers of shocks in the outskirts of merging galaxy clusters. PSZ2 G200.95–28.16, a low-mass merging cluster ( M 500 = (2.7 ± 0.2) × 10 14 M ⊙ ), features a prominent radio relic, first identified by R. Kale et al. We name this relic as the Seahorse. The MeerKAT Galaxy Cluster Legacy Survey has confirmed two additional radio relics, R2 and R3, in this cluster. We present new observations of this cluster with the upgraded Giant Metrewave Radio Telescope (uGMRT) at 400 and 650 MHz, paired with Chandra X-ray data. The largest linear sizes for the three relics are 1.53 Mpc, 1.12 kpc, and 340 kpc. All three radio relics are polarized at 1283 MHz. Assuming the diffusive shock acceleration model, the spectral indices of the relics imply shock Mach Numbers of 3.1 ± 0.8 and 2.8 ± 0.9 for the Seahorse and R2, respectively. The Chandra X-ray surface brightness map shows two prominent subclusters, but the relics are not perpendicular to the likely merger axis, as typically observed; no shocks are detected at the locations of the relics. We discuss possible merger scenarios in light of the low mass of the cluster and the radio and X-ray properties of the relics. The relic R2 follows the correlation known in the radio relic power and cluster-mass plane, but the Seahorse and R3 relics are outliers. We have also discovered a radio ring in our 650 MHz uGMRT image that could be an Odd Radio Circle candidate.}, archive = {J_ApJ}, author = {Arpan Pal and Ruta Kale and Qian H. S. Wang and Daniel R. Wik}, doi = {10.3847/1538-4357/ad9903}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {4}, shortjournal = {The Astrophys. J.}, title = {A uGMRT and MeerKAT study of radio relics in the low-mass merging cluster PSZ2 g200.95−28.16}, volume = {979}, year = {2025}, }
• (2025). Probing cosmic isotropy with the FAST all sky h i survey. ApJ, 979(1), 3. (www)

  @article{ , abstract = {This paper leverages the first released catalog from the FAST All Sky H i Survey (FASHI) to examine the hypothesis of cosmic isotropy in the local Universe. Given the design of the overall FAST survey, the inhomogeneous detection sensitivity of FASHI is likely to introduce significant biases in the statistical properties of the catalog. To mitigate the potential influence of spurious clustering effects due to these sensitivity variations, we focus on extragalactic H i sources within the sensitivity range of [0.65, 1.0]. This refined subsample is divided into 10 distinct sky regions, for which we compute the two-point angular correlation functions (2PACF) over angular scales of 0 \mathop{.}\limits^{\unicode{x000b0}} 5 < θ < 10°. We apply the Markov Chain Monte Carlo method to fit these 2PACFs with a power-law model and assess the statistical significance of the best-fit parameters for the 10 FASHI sky regions by comparing them against results from mock catalogs generated under the assumptions of homogeneity and isotropy. Our findings indicate that the local Universe, as traced by the H i sources in the FASHI survey, aligns with the cosmic isotropy hypothesis within a 2 σ confidence level. We do not detect any statistically significant deviations from cosmic isotropy in the FASHI survey data.}, archive = {J_ApJ}, author = {Yi-Wen Wu and Jun-Qing Xia}, doi = {10.3847/1538-4357/ad9922}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {3}, shortjournal = {The Astrophys. J.}, title = {Probing cosmic isotropy with the FAST all sky h i survey}, volume = {979}, year = {2025}, }
• (2025). Testing the cosmic distance duality relation using strong gravitational lensing time delays and type ia supernovae. ApJ, 979(1), 2. (www)

  @article{ , abstract = {We present a comprehensive test of the cosmic distance duality relation (DDR) using a combination of strong gravitational lensing (SGL) time delay measurements and Type Ia supernovae (SNe Ia) data. We investigate three different parameterizations of potential DDR violations. To bridge the gap between SGL and SNe Ia data sets, we implement an artificial neural network approach to reconstruct the distance modulus of SNe Ia. Our analysis uniquely considers both scenarios where the absolute magnitude of SNe Ia ( M B ) is treated as a free parameter and where it is fixed to a Cepheid-calibrated value. Using a sample of six SGL systems and the Pantheon+ SNe Ia data set, we find no statistically significant evidence for DDR violations across all parameterizations. The consistency of our findings across different parameterizations not only reinforces confidence in the standard DDR but also demonstrates the robustness of our analytical approach.}, archive = {J_ApJ}, author = {Jing-Zhao Qi and Yi-Fan Jiang and Wan-Ting Hou and Xin Zhang}, doi = {10.3847/1538-4357/ad9de4}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {2}, shortjournal = {The Astrophys. J.}, title = {Testing the cosmic distance duality relation using strong gravitational lensing time delays and type ia supernovae}, volume = {979}, year = {2025}, }
• (2025). PKS 2332–017 and PMN j1916–1519: Candidate blazar counterparts to two high-energy neutrino events. ApJ, 979(1), 1. (www)

  @article{ , abstract = {We report our counterpart identification study for two high-energy neutrino events IC-130127A and IC-131204A listed in the IceCube Event Catalog of Alert Tracks. These two events belong to Gold alerts, which have a significant probability of being of astrophysical origin. Within the events' 90% positional uncertainty regions, we, respectively, find PKS 2332–017 and PMN J1916–1519. The first source is a flat-spectrum radio quasar at redshift z = 1.18, and the second is a blazar of an uncertain type with photometric z = 0.968. As they correspondingly had a γ -ray flare temporally coincident with the arrival times of IC-130127A and IC-131204A, we identify them as the respective neutrino emitters. Detailed analysis of the γ -ray data for the two blazars, obtained with the Large Area Telescope onboard the Fermi Gamma-ray Space Telescope, is conducted. The two flares, respectively, from PKS 2332–017 and PMN J1916–1519 lasted ~4 yr and ~4 months and showed possible emission hardening by containing high-energy ~2–10 GeV photons in the emissions. Accompanying the flare of PKS 2332–017, optical and mid-infrared brightening variations were also observed. We discuss the properties of the two sources and compare the properties with those of the previously reported (candidate) neutrino-emitting blazars.}, archive = {J_ApJ}, author = {Shunhao Ji and Zhongxiang Wang and Dong Zheng}, doi = {10.3847/1538-4357/ad9f40}, journal = {The Astrophysical Journal}, month = {1}, number = {1}, pages = {1}, shortjournal = {The Astrophys. J.}, title = {PKS 2332–017 and PMN j1916–1519: Candidate blazar counterparts to two high-energy neutrino events}, volume = {979}, year = {2025}, }
• (2025). Determining the nature of IC 10 X-2: A comprehensive study of the Optical/IR emission from an extragalactic BeHMXB. ApJ, 978(2), 170. (www)

  @article{ , abstract = {We present a comprehensive analysis of the optical and infrared (IR) properties of high-mass X-ray binary (HMXB) IC 10 X-2, classified as a supergiant HMXB and superfast X-ray transient by previous work. Our analysis of regular (daily and weekly) observations by both the Zwicky Transient Facility and Las Cumbres Observatory over a 5 yr period indicates both periodic flares and variations in the apparent magnitude and color with a period of ∼26.5 days—likely the orbital period of this binary system. The periodic flaring suggests the stellar companion is a Be star, with flares resulting from increased accretion onto the neutron star (NS) when it enters the stellar decretion disk. The periodic variations in the optical/IR brightness and color likely result from orbital variations in the hydrogen column density along the line of sight or a transient accretion disk around the NS. Lastly, the numerous short-duration episodes where IC 10 X-2 is significantly "redder" or "bluer" than normal likely result from clumps within this system—which can accrete onto the NS (causing IC 10 X-2 to appear bluer) or pass through the line of sight (causing IC 10 X-2 to appear redder). These results substantially increase our understanding of the evolution of this source, which is a significant source of ionizing photons in its host galaxy IC 10, a low-mass, metal-poor starburst galaxy similar in many respects to those thought to be common in the early Universe.}, archive = {J_ApJ}, author = {Jwaher Alnaqbi and Joseph D. Gelfand and Payaswini Saikia and Craig Heinke and M. C. Baglio and David M. Russell and Guobao Zhang and Antonios Manousakis and Ivan Yu. Katkov and Fraser Lewis}, doi = {10.3847/1538-4357/ad82df}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {170}, shortjournal = {The Astrophys. J.}, title = {Determining the nature of IC 10 X-2: A comprehensive study of the Optical/IR emission from an extragalactic BeHMXB}, volume = {978}, year = {2025}, }
• (2025). Detectability of self-lensing flares of white dwarfs with compact companions. ApJ, 978(2), 169. (www)

  @article{ , abstract = {Binaries containing compact objects, viewed nearly edge on, can produce periodic brightening events under certain conditions on the masses, radii, and binary separation. Such flares are caused by one object gravitationally lensing another, in what is known as self-lensing flares . We present a simulation tool that efficiently reproduces the main features of self-lensing flares and facilitates a detection sensitivity analysis for various sky surveys. We estimate the detection prospects for a handful of representative surveys when searching for systems of either two white dwarfs or a white dwarf with other compact objects, i.e., neutron stars and black holes. We find only a marginal ability to detect such systems in existing surveys. However, we estimate many such systems could be detectable by surveys in the near future, including the Vera Rubin Legacy Survey of Space and Time (LSST). We provide a quantitative analysis of the detectability of double-compact object self-lensing flares across the landscape of system parameters, and a qualitative discussion of survey and follow-up approaches to distinguish such flares from confounding events, such as stellar flares, satellite glints, and cosmic rays. We estimate 0.3, 3 and 247 double white dwarf systems could be detected by Transiting Exoplanet Survey Satellite, Zwicky Transient Facility, and LSST, respectively. A similar number of systems with a neutron star or black hole companion could be detected, but we caution that the number densities of such binaries is model dependent and so are our detection estimates. Such binaries can be used to constrain models of the end states of binary evolution.}, archive = {J_ApJ}, author = {Guy Nir and Joshua S. Bloom}, doi = {10.3847/1538-4357/ad9398}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {169}, shortjournal = {The Astrophys. J.}, title = {Detectability of self-lensing flares of white dwarfs with compact companions}, volume = {978}, year = {2025}, }
• (2025). The NANOGrav 15 yr data set: Removing pulsars one by one from the pulsar timing array. ApJ, 978(2), 168. (www)

  @article{ , abstract = {Evidence has emerged for a stochastic signal correlated among 67 pulsars within the 15 yr pulsar-timing data set compiled by the NANOGrav collaboration. Similar signals have been found in data from the European, Indian, Parkes, and Chinese pulsar timing arrays. This signal has been interpreted as indicative of the presence of a nanohertz stochastic gravitational-wave background (GWB). To explore the internal consistency of this result, we investigate how the recovered signal strength changes as we remove the pulsars one by one from the data set. We calculate the signal strength using the (noise-marginalized) optimal statistic, a frequentist metric designed to measure the correlated excess power in the residuals of the arrival times of the radio pulses. We identify several features emerging from this analysis that were initially unexpected. The significance of these features, however, can only be assessed by comparing the real data to synthetic data sets. After conducting identical analyses on simulated data sets, we do not find anything inconsistent with the presence of a stochastic GWB in the NANOGrav 15 yr data. The methodologies developed here can offer additional tools for application to future, more sensitive data sets. While this analysis provides an internal consistency check of the NANOGrav results, it does not eliminate the necessity for additional investigations that could identify potential systematics or uncover unmodeled physical phenomena in the data.}, archive = {J_ApJ}, author = {Gabriella Agazie and Akash Anumarlapudi and Anne M. Archibald and Zaven Arzoumanian and Jeremy G. Baier and Paul T. Baker and Bence Bécsy and Laura Blecha and Adam Brazier and Paul R. Brook and Sarah Burke-Spolaor and J. Andrew Casey-Clyde and Maria Charisi and Shami Chatterjee and Tyler Cohen and James M. Cordes and Neil J. Cornish and Fronefield Crawford and H. Thankful Cromartie and Kathryn Crowter and Megan E. DeCesar and Paul B. Demorest and Heling Deng and Lankeswar Dey and Timothy Dolch and Elizabeth C. Ferrara and William Fiore and Emmanuel Fonseca and Gabriel E. Freedman and Emiko C. Gardiner and Nate Garver-Daniels and Peter A. Gentile and Kyle A. Gersbach and Joseph Glaser and Deborah C. Good and Lydia Guertin and Kayhan Gültekin and Jeffrey S. Hazboun and Ross J. Jennings and Aaron D. Johnson and Megan L. Jones and Andrew R. Kaiser and David L. Kaplan and Luke Zoltan Kelley and Matthew Kerr and Joey S. Key and Nima Laal and Michael T. Lam and William G. Lamb and Bjorn Larsen and T. Joseph W. Lazio and Natalia Lewandowska and Tingting Liu and Duncan R. Lorimer and Jing Luo and Ryan S. Lynch and Chung-Pei Ma and Dustin R. Madison and Alexander McEwen and James W. McKee and Maura A. McLaughlin and Natasha McMann and Bradley W. Meyers and Patrick M. Meyers and Hannah Middleton and Chiara M. F. Mingarelli and Andrea Mitridate and Christopher J. Moore and Cherry Ng and David J. Nice and Stella Koch Ocker and Ken D. Olum and Timothy T. Pennucci and Benetge B. P. Perera and Nihan S. Pol and Henri A. Radovan and Scott M. Ransom and Paul S. Ray and Joseph D. Romano and Jessie C. Runnoe and Alexander Saffer and Shashwat C. Sardesai and Ann Schmiedekamp and Carl Schmiedekamp and Kai Schmitz and Brent J. Shapiro-Albert and Xavier Siemens and Joseph Simon and Magdalena S. Siwek and Sophia V. Sosa Fiscella and Ingrid H. Stairs and Daniel R. Stinebring and Kevin Stovall and Abhimanyu Susobhanan and Joseph K. Swiggum and Stephen R. Taylor and Jacob E. Turner and Caner Unal and Michele Vallisneri and Alberto Vecchio and Sarah J. Vigeland and Haley M. Wahl and Caitlin A. Witt and David Wright and Olivia Young}, doi = {10.3847/1538-4357/ad93aa}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {168}, shortjournal = {The Astrophys. J.}, title = {The NANOGrav 15 yr data set: Removing pulsars one by one from the pulsar timing array}, volume = {978}, year = {2025}, }
• (2025). The size of accretion disks from self-consistent X-ray spectra and UV/Optical/NIR photometry fitting: Applications to ASASSN–14li and HLX–1. ApJ, 978(2), 167. (www)

  @article{ , abstract = {We implement a standard thin disk model with the outer disk radius ( R out ) as a free parameter, integrating it into a standard X-ray fitting package to enable self-consistent and simultaneous fitting of X-ray spectra and Ultraviolet (UV), Optical, and Near-infrared (NIR) photometry. We apply the model to the late-time data (Δ t ≈ 350–1300 days) of the tidal disruption event (TDE) ASASSN–14li. We show that at these late times, the multiwavelength emission of the source can be fully described by a bare compact accretion disk. We obtain a black hole mass ( M BH ) of {7}_{-2}^{+3}\times 1{0}^{6}{M}_{\odot } , consistent with host-galaxy scaling relations, and an R out of 45 ± 13 R g , consistent with the circularization radius, with possible expansion at the latest epoch. We discuss how simplistic models, such as a single-temperature blackbody fitted to either X-ray spectra or UV/optical photometry, lead to erroneous interpretations of the scale/energetics of TDE emission. We also apply the model to the soft/high state of the intermediate-mass black hole candidate HLX–1. The model fits the full spectral energy distribution (from X-rays to NIR) without needing an additional stellar population component. We investigate how relativistic effects improve our results by implementing a version of the model with full ray tracing calculations in the Kerr metric. For HLX–1, we find {M}_{{\rm{BH}}}={4}_{-1}^{+3}\times 1{0}^{4}{M}_{\odot } and R out ≈ few × 10 3 R g , in agreement with previous findings. The relativistic model can constrain the inclination ( i ) of HLX–1 to be 10° ≤ i ≤70°.}, archive = {J_ApJ}, author = {Muryel Guolo and Andrew Mummery}, doi = {10.3847/1538-4357/ad990a}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {167}, shortjournal = {The Astrophys. J.}, title = {The size of accretion disks from self-consistent X-ray spectra and UV/Optical/NIR photometry fitting: Applications to ASASSN–14li and HLX–1}, volume = {978}, year = {2025}, }
• (2025). Characterizing stellar and gas properties in NGC 628: Spatial distributions, radial gradients, and resolved scaling relations. ApJ, 978(2), 166. (www)

  @article{ , abstract = {Building on our previous research involving multiwavelength data from UV to IR, we employ spectroscopic observations of ionized gas, as well as neutral hydrogen gas obtained from the Five-hundred Meter Aperture Spherical Telescope (FAST), to explore the intrinsic processes of star formation and chemical enrichment within NGC 628. Our analysis focuses on several key properties, including gas-phase extinction, star formation rate (SFR) surface density, oxygen abundance, and H i mass surface density. The azimuthal distributions of these parameters in relation to the morphological and kinematic features revealed by FAST H i reveal that NGC 628 is an isolated galaxy that has not undergone recent interactions. We observe a mild radial extinction gradient accompanied by a notable dispersion. The SFR surface density also shows a gentle radial gradient, characteristic of typical spiral galaxies. Additionally, we find a negative radial metallicity gradient of −0.44 dex {R}_{25}^{-1} , supporting the "inside-out" scenario of galaxy formation. We investigate the resolved mass–metallicity relation (MZR) and the resolved star formation main sequence (SFMS) alongside their dependences on the physical properties of both ionized and neutral hydrogen gas. Our findings indicate no secondary dependence of the resolved MZR on SFR surface density or H i mass surface density. Furthermore, we observe that gas-phase extinction and the equivalent width of H α both increase with SFR surface density in the resolved SFMS.}, archive = {J_ApJ}, author = {Peng Wei and Hu Zou and Jing Wang and Xu Kong and Shuguo Ma and Ruilei Zhou and Xu Zhou and Ali Esamdin and Jiantao Sun and Tuhong Zhong and Fei Dang}, doi = {10.3847/1538-4357/ad9a51}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {166}, shortjournal = {The Astrophys. J.}, title = {Characterizing stellar and gas properties in NGC 628: Spatial distributions, radial gradients, and resolved scaling relations}, volume = {978}, year = {2025}, }
• (2025). ALESS-JWST: Joint (Sub)kiloparsec JWST and ALMA imaging of z ~ 3 submillimeter galaxies reveals heavily obscured bulge formation events. ApJ, 978(2), 165. (www)

  @article{ , abstract = {We present JWST NIRCam imaging targeting 13 z ~ 3 infrared-luminous ( L IR ∼ 5 × 10 12 L ⊙ ) galaxies from the ALESS survey with uniquely deep, high-resolution (0 \mathop{.}\limits^{\unicode{x02033}} 08–0 \mathop{.}\limits^{^{\prime\prime} } 16) Atacama Large Millimeter/submillimeter Array 870 μ m imaging. The 2.0–4.4 μ m (observed frame) NIRCam imaging reveals the rest-frame near-infrared stellar emission in these submillimeter-selected galaxies at the same (sub)kiloparsec resolution as the 870 μ m dust continuum. The newly revealed stellar morphologies show striking similarities with the dust continuum morphologies at 870 μ m, with the centers and position angles agreeing for most sources, clearly illustrating that the spatial offsets reported previously between the 870 μ m and Hubble Space Telescope morphologies were due to strong differential dust obscuration. The F444W sizes are 78% ± 21% larger than those measured at 870 μ m, in contrast to recent results from hydrodynamical simulations that predict larger 870 μ m sizes. We report evidence for significant dust obscuration in F444W for the highest-redshift sources, emphasizing the importance of longer-wavelength MIRI imaging. The majority of the sources show evidence that they are undergoing mergers/interactions, including tidal tails/plumes—some of which are also detected at 870 μ m. We find a clear correlation between NIRCam colors and 870 μ m surface brightness on  ∼1 kpc scales, indicating that the galaxies are primarily red due to dust—not stellar age—and we show that the dust structure on  ∼kpc scales is broadly similar to that in nearby galaxies. Finally, we find no strong stellar bars in the rest-frame near-infrared, suggesting the extended bar-like features seen at 870 μ m are highly obscured and/or gas-dominated structures that are likely early precursors to significant bulge growth.}, archive = {J_ApJ}, author = {J. A. Hodge and E. da Cunha and S. Kendrew and J. Li and I. Smail and B. A. Westoby and O. Nayak and A. M. Swinbank and C.-C. Chen and F. Walter and P. van der Werf and M. Cracraft and A. Battisti and W. N. Brandt and G. Calistro Rivera and S. C. Chapman and P. Cox and H. Dannerbauer and R. Decarli and M. Frias Castillo and T. R. Greve and K. K. Knudsen and S. Leslie and K. M. Menten and M. Rybak and E. Schinnerer and J. L. Wardlow and A. Weiss}, doi = {10.3847/1538-4357/ad9a52}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {165}, shortjournal = {The Astrophys. J.}, title = {ALESS-JWST: Joint (Sub)kiloparsec JWST and ALMA imaging of z ~ 3 submillimeter galaxies reveals heavily obscured bulge formation events}, volume = {978}, year = {2025}, }
• (2025). A new approach to constraining properties of active galactic nucleus host galaxies by combining image and spectral energy distribution decomposition: Testing upon the MBH–M⋆ relation. ApJ, 978(2), 164. (www)

  @article{ , abstract = {The outshining light from active galactic nuclei (AGNs) poses significant challenges in studying the properties of AGN host galaxies. To address this issue, we propose a novel approach that combines image decomposition and spectral energy distribution (SED) decomposition to constrain the properties of AGN host galaxies. Image decomposition allows us to disentangle optical flux into AGN and stellar components, thereby providing additional constraints on the SED models to derive a more refined stellar mass. To test the viability of this approach, we obtained a sample of 24 X-ray-selected type I AGNs with redshifts ranging from 0.73 to 2.47. We estimated the stellar masses for our sample and found that our results are generally consistent with earlier estimates based on different methods. Through examining the posterior distribution of stellar masses, we find that our method could derive better-constrained results compared to previous SED decomposition methods. With the derived stellar masses, we further studied the M BH – M ⋆ relation of our sample, finding a higher intrinsic scatter in the correlation for our entire sample compared to the local quiescent correlation, which could be caused by a few "black hole monsters" in our sample. We propose that, based on our method, future works could extend to larger samples of high-redshift AGN host galaxies, thereby enhancing our understanding of their properties.}, archive = {J_ApJ}, author = {Haoran Yu and Lulu Fan and Yunkun Han and Weibin Sun and Yihang Zhang and Xuheng Ding and Yongquan Xue}, doi = {10.3847/1538-4357/ad9aa3}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {164}, shortjournal = {The Astrophys. J.}, title = {A new approach to constraining properties of active galactic nucleus host galaxies by combining image and spectral energy distribution decomposition: Testing upon the MBH–M⋆ relation}, volume = {978}, year = {2025}, }
• (2025). SN 2014C: A metamorphic supernova exploded in the intricate and hydrogen-rich surroundings. ApJ, 978(2), 163. (www)

  @article{ , abstract = {We present photometric and spectroscopic observations of supernova (SN) SN 2014C, primarily emphasizing the initial month after the explosion at approximately daily intervals. During this time, it was classified as a Type Ib SN exhibiting a notably higher peak luminosity ( L peak ≈ 4.3 × 10 42 erg s −1 ), a faster rise to brightness ( t rise ≈ 11.6 days), and a more gradual dimming ( {\rm{\Delta }}{m}_{15}^{V}\approx 0.48 mag) compared to typical Type Ib SNe. Analysis of the velocity evolution over the first ~20 days after the explosion supports the view that the absorption near 6200 Å is due to high-velocity H α in the outer layers of the ejecta, indicating the presence of a small amount of hydrogen in the envelope of the progenitor before the explosion. Assuming that the peak luminosity is entirely attributed to radioactive decay, we estimate that 0.14 M ⊙ of 56 Ni was synthesized in the explosion. However, this amount of nickel could no longer maintain observed brightness approximately 10 days after peak luminosity, suggesting additional energy sources beyond radioactive decay. This supplementary energy likely originates from interaction with the circumstellar medium (CSM). Consequently, the timing of the SN−CSM interaction in SN 2014C may occur much earlier than the emergence of Type IIn−like features during the nebular phase.}, archive = {J_ApJ}, author = {Qian Zhai and Jujia Zhang and Weili Lin and Paolo Mazzali and Elena Pian and Stefano Benetti and Lina Tomasella and Jialian Liu and Liping Li}, doi = {10.3847/1538-4357/ad9c76}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {163}, shortjournal = {The Astrophys. J.}, title = {SN 2014C: A metamorphic supernova exploded in the intricate and hydrogen-rich surroundings}, volume = {978}, year = {2025}, }
• (2025). Constraining anisotropic diffusion between geminga and earth with the cosmic-ray electron and positron spectrum. ApJ, 978(2), 162. (www)

  @article{ , abstract = {The gamma-ray halo around Geminga indicates significant suppression of cosmic-ray diffusion. One possible explanation for this phenomenon is the projection effect of slow diffusion perpendicular to the mean magnetic field (characterized by the diffusion coefficient D ⊥ ) within an anisotropic diffusion framework. In this scenario, the diffusion coefficient parallel to the mean field ( D ∥ ) can still be large, enabling electrons and positrons ( e ± ) produced by Geminga to efficiently travel to Earth along the magnetic field lines, possibly resulting in a detectable e ± flux. In this work, we first determine the basic parameters of the anisotropic model using the morphology and spectral measurements of the Geminga halo and then predict the flux of e ± produced by Geminga at the location of Earth. We find that the e − + e + spectrum of DAMPE can give crucial constraint on the anisotropic diffusion model: to ensure that the predicted spectrum does not exceed the measurements, the Alfvén Mach number of the turbulent magnetic field ( M A ) should not be less than 0.75, corresponding to D ∥ / D ⊥ ≲ 3 given that {D}_{\perp }={D}_{\parallel }{M}_{A}^{4} . This implies that a significant suppression of D ∥ relative to the average value in the Galaxy may still be necessary. Furthermore, we find that under the anisotropic diffusion model, Geminga can produce a very sharp feature around 1 TeV in the e − + e + spectrum, which could naturally explain the peculiar 1.4 TeV excess tentatively observed by DAMPE.}, archive = {J_ApJ}, author = {Junji Xia and Xiaojun Bi and Kun Fang and Siming Liu}, doi = {10.3847/1538-4357/ad9d39}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {162}, shortjournal = {The Astrophys. J.}, title = {Constraining anisotropic diffusion between geminga and earth with the cosmic-ray electron and positron spectrum}, volume = {978}, year = {2025}, }
• (2025). The long-term evolution of the solar transition region. ApJ, 978(2), 161. (www)

  @article{ , abstract = {Long-term evolution characteristics of the solar transition region have been unclear. In this study, daily images of the solar full disk derived from the observations by the Solar Dynamics Observatory/Atmospheric Imaging Assembly at 304 Å wavelength from 2011 January 1 to 2022 December 31 are used to investigate the long-term evolution of the solar transition region. It is found that long-term variation in the transition region of the full disk is in phase with the solar activity cycle, and thus the polar brightening should occur in the maximum epoch of the solar cycle. Long-term variation of the background transition region is found to be likely in antiphase with the solar activity cycle at middle and low latitudes. The entire transition region, especially the active transition region is inferred to be mainly heated by the active-region magnetic fields and the ephemeral-region magnetic fields, while the quieter transition region is believed to be mainly heated by network magnetic fields. Long-term evolution characteristics of various types of the magnetic fields at the solar surface are highly consistent with these findings, and thus provide an explanation for them.}, archive = {J_ApJ}, author = {W. Q. Chen and K. J. Li and J. C. Xu}, doi = {10.3847/1538-4357/ad9d44}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {161}, shortjournal = {The Astrophys. J.}, title = {The long-term evolution of the solar transition region}, volume = {978}, year = {2025}, }
• (2025). Comparison of the origin of short gamma-ray bursts with or without extended emission. ApJ, 978(2), 160. (www)

  @article{ , abstract = {The merger of compact binary stars produces short gamma-ray bursts (sGRBs), involving channels such as neutron star–neutron star (BNS) and neutron star–black hole (NS–BH). The association between sGRB 170817A and gravitational wave GW170817 provides reliable evidence for the BNS channel. Some speculations suggest that sGRBs with extended emission (EE) may represent another distinct population. The offset is the distance between the GRB sky localization and the host galaxy center. We compared the offset distributions of these two types of samples (46 sGRBs with EE and 9 without EE samples) and found that they follow the same distribution. Utilizing nonparametric methods, we examined the luminosity function and formation rate of sGRBs without any assumptions. The luminosity function can be described as \psi ({L}_{0})\propto {L}_{0}^{-0.12\pm 0.01} for {L}_{0}\lt {L}_{0}^{b} ( \psi ({L}_{0})\propto {L}_{0}^{-0.73\pm 0.02} and for {L}_{0}\gt {L}_{0}^{b} ) for sGRBs without EE and \psi ({L}_{0})\propto {L}_{0}^{-0.13\pm 0.003} for {L}_{0}\lt {L}_{0}^{b} ( \psi ({L}_{0})\propto {L}_{0}^{-0.61\pm 0.01} and for {L}_{0}\gt {L}_{0}^{b} ) for sGRBs with EE. The formation rate is characterized as ρ ( z ) ∝ (1 + z ) −3.04±0.10 for z < 1 and as ρ ( z ) ∝ (1 + z ) −0.29±0.38 for 1 < z < 3 for sGRBs without EE, while for sGRBs with EE, it is ρ ( z ) ∝ (1 + z ) −3.85±0.15 for z < 1 and ρ ( z ) ∝ (1 + z ) −0.40±1.11 for 1 < z < 3. Our findings suggest no significant difference in the progenitors of sGRBs with and without EE when considered in terms of spatial offsets, formation rates, and luminosity function.}, archive = {J_ApJ}, author = {Qin-Mei Li and Qi-Bin Sun}, doi = {10.3847/1538-4357/ad82e2}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {160}, shortjournal = {The Astrophys. J.}, title = {Comparison of the origin of short gamma-ray bursts with or without extended emission}, volume = {978}, year = {2025}, }
• (2025). H i intensity mapping cross-correlation with thermal Sunyaev–Zel’dovich fluctuations: Forecasted cosmological parameter estimation for FAST and planck. ApJ, 978(2), 159. (www)

  @article{ , abstract = {The 21 cm emission from neutral hydrogen surveys holds great potential as a valuable method for exploring the large-scale structure (LSS) of the Universe. In this paper, we forecast for the cross-correlation between the thermal Sunyaev–Zel'dovich (SZ) fluctuations as probed by the Planck satellite and fluctuations in the H i brightness temperature as probed by the ground-based Five-hundred-meter Aperture Spherical Telescope to trace the connection between galaxy clusters and the H i LSS. Assuming that the measurement is limited by instrumental noise rather than by foreground, we estimate the potential detectability of the cross-correlation signal and the improvement in the measurement of the H i cosmic density, the hydrostatic mass bias parameter, and the universal pressure profile parameters. We obtain a constraint on the cosmic neutral hydrogen density parameter significantly to σ (Ω H I ) = 1.0 × 10 −6 . We also find that the average halo masses contributing to the H i − y cross-power spectrum in the one-halo regime is ∼1.5 × 10 14 M ⊙ . Our results also show that the H i –SZ cross-correlation has great potential to probe the distribution of neutral hydrogen (H i ) within halos at low redshift.}, archive = {J_ApJ}, author = {Ayodeji Ibitoye and Furen Deng and Yichao Li and Yin-Zhe Ma and Yan Gong and Xuelei Chen}, doi = {10.3847/1538-4357/ad91a4}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {159}, shortjournal = {The Astrophys. J.}, title = {H i intensity mapping cross-correlation with thermal Sunyaev–Zel’dovich fluctuations: Forecasted cosmological parameter estimation for FAST and planck}, volume = {978}, year = {2025}, }
• (2025). Dwarf galaxies with radio-excess active galactic nuclei in the very large array sky survey. ApJ, 978(2), 158. (www)

  @article{ , abstract = {We present a systematic search for radio active galactic nuclei (AGNs) in dwarf galaxies using recent observations taken by the Very Large Array Sky Survey (VLASS). To select these objects, we first establish a criterion to identify radio-excess AGNs using the infrared-radio correlation parameter, q , that describes the tight relation between radio and IR emission in star-forming galaxies. We find a 2 σ threshold of q < 1.94 to select radio-excess AGNs, which is derived from a sample of ∼7000 galaxies across the full mass range in the NASA-Sloan Atlas that have radio and IR detections from VLASS and the Wide-Field Infrared Survey Explorer, respectively. We create catalogs of radio-excess AGNs and star-forming galaxies and make these available to the community. Applying our criterion to dwarf galaxies with stellar masses M ⋆ ≲ 3 × 10 9 M ⊙ and redshifts z ≤ 0.15, and carefully removing interlopers, we find 10 radio-excess AGNs with radio-optical positional offsets between ∼0'' and 2 3 (0–2.7 kpc). Based on statistical arguments and emission line diagnostics, we expect the majority of these radio-excess AGNs to be associated with the dwarf host galaxies rather than background AGNs. Five of the objects have evidence for hosting AGNs at other wavelengths, and five objects are identified as AGNs in dwarf galaxies for the first time. We also identify eight variable radio sources in dwarf galaxies by comparing the VLASS epoch 1 and epoch 2 observations to Faint Images of the Radio Sky at Twenty-centimeters detections presented in A. E. Reines et al. (2020).}, archive = {J_ApJ}, author = {John-Michael Eberhard and Amy E. Reines and Hansung B. Gim and Jeremy Darling and Jenny E. Greene}, doi = {10.3847/1538-4357/ad9584}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {158}, shortjournal = {The Astrophys. J.}, title = {Dwarf galaxies with radio-excess active galactic nuclei in the very large array sky survey}, volume = {978}, year = {2025}, }
• (2025). Dependence of SYMH change rate on dynamic pressure during the main phases of storms: A comparative analysis of the 2024 may and 2003 november superstorms. ApJ, 978(2), 157. (www)

  @article{ , abstract = {We denote the variation in the SYMH index during the main phase of a geomagnetic storm as ΔSYMH and the duration of the storm's main phase as Δ t . The ratio ΔSYMH/Δ t represents the averaged rate of change of the ring current throughout the main phase of the storm. We analyzed the ΔSYMH/Δ t ratios during the main phases of the 2024 May superstorm (referred to as storm1) and the 2003 November superstorm (referred to as storm2), followed by a comparison of the solar wind parameters that significantly influenced the main phases of these two events. We discovered that the ΔSYMH/Δ t ratio for storm1 exceeded that of storm2. Additionally, the time integral of the solar wind electric field during the main phase of storm1 was less than that of storm2, which suggests that ΔSYMH/Δ t is not solely determined by the solar wind electric field. Our findings also indicated that the average dynamic pressure during the main phase of storm1 was larger than that of storm2, highlighting the significance of dynamic pressure as a key parameter in influencing the variation of the ring current during the main phase of a geomagnetic storm.}, archive = {J_ApJ}, author = {Ming-Xian Zhao and Gui-Ming Le}, doi = {10.3847/1538-4357/ada15c}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {157}, shortjournal = {The Astrophys. J.}, title = {Dependence of SYMH change rate on dynamic pressure during the main phases of storms: A comparative analysis of the 2024 may and 2003 november superstorms}, volume = {978}, year = {2025}, }
• (2025). The deuterium fractionation of NH3 in massive star-forming regions. ApJ, 978(2), 156. (www)

  @article{ , abstract = {Deuteration is sensitive to environmental conditions in star-forming regions. To investigate NH 2 D chemistry, we compared the spatial distribution of ortho-NH 2 D {1}_{11}^{s}-{1}_{01}^{a} , NH 3 (1,1), and NH 3 (2,2) in 12 late-stage massive star-forming regions. By averaging several pixels along the spatial slices of ortho-NH 2 D {1}_{11}^{s}-{1}_{01}^{a} , we obtained the deuterium fractionation of NH 3 . In seven targets, the deuterium fractionation of NH 3 shows a decreasing trend with increasing rotational temperature. This trend is less clear in the remaining five sources, likely due to limited spatial resolution. However, when considering all 12 sources together, the anticorrelation between NH 3 deuterium fractionation and rotational temperature becomes less significant, suggesting that other physical parameters may influence the fractionation. Additionally, we found that the region of highest deuterium fractionation of NH 3 is offset from the NH 3 peak in each source, likely because the temperature is higher near the NH 3 peaks and NH 2 D may be depleted from the gas phase as the molecular cloud core evolves, as well as the increased release of CO from grains into the gas phase.}, archive = {J_ApJ}, author = {Yuqiang Li and Junzhi Wang and Juan Li and Prathap Rayalacheruvu and Liton Majumdar and Yaoting Yan and Donghui Quan and Xing Lu and Siqi Zheng}, doi = {10.3847/1538-4357/ad8444}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {156}, shortjournal = {The Astrophys. J.}, title = {The deuterium fractionation of NH3 in massive star-forming regions}, volume = {978}, year = {2025}, }
• (2025). Spherical accretion in the schwarzschild spacetime in the newtonian analogous construct. ApJ, 978(2), 155. (www)

  @article{ , abstract = {The velocity-dependent Newtonian analogous potentials (NAPs) corresponding to general relativistic (GR) spacetimes accurately capture most of the relativistic features, including all classical tests of GR, effectively representing spacetime geometries in Newtonian terms. The NAP formulated by Tejeda & Rosswog (TR13) for Schwarzschild spacetime has been applied to the standard thin accretion disk around a black hole (BH) as well as in the context of streamlines of noninteracting particles accreting onto a Schwarzschild BH, showing good agreement with the exact relativistic solutions. As a further application, here we explore the extent to which TR13 NAP could describe a transonic hydrodynamical spherical accretion flow in Schwarzschild spacetime within the framework of standard Newtonian hydrodynamics. Instead of obtaining a typical single "saddle-type" sonic transition, a "saddle–spiral pair" is produced, with the inner sonic point being an (unphysical) "spiral type" and the outer being a usual "saddle type." The Bondi accretion rate at outer sonic radii, however, remains consistent with that of the GR case. The primary reason for the deviation of our findings from the classical Bondi solution is likely due to the inconsistency between the Euler-type equation in the presence of velocity-dependent TR13 NAP within the standard Newtonian hydrodynamics framework, and the corresponding GR Euler equation, regardless of the fluid's energy. Our study suggests that a (modified) hydrodynamical formalism is needed to effectively implement such potentials in transonic accretion studies that align with the spirit of TR13 like NAP, while remaining consistent with the GR hydrodynamics. This could then essentially circumvent GR hydrodynamics or GR magnetohydrodynamics equations}, archive = {J_ApJ}, author = {Shubhrangshu Ghosh and Souvik Ghose and Kalyanbrata Pal and Arunabha Bhadra and Tapas K. Das}, doi = {10.3847/1538-4357/ad901f}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {155}, shortjournal = {The Astrophys. J.}, title = {Spherical accretion in the schwarzschild spacetime in the newtonian analogous construct}, volume = {978}, year = {2025}, }
• (2025). Chemical fingerprints of m dwarfs: High-resolution spectroscopy on 31 m dwarfs with SPIRou. ApJ, 978(2), 154. (www)

  @article{ , abstract = {We extend the methodology introduced by F. Jahandar et al. to determine the effective temperature and chemical abundances of 31 slowly rotating solar neighborhood M dwarfs (M1–M5) using high-resolution spectra from CFHT/SPIRou. This group includes 10 M dwarfs in binary systems with FGK primaries of known metallicity from optical measurements. By testing our T eff method on various synthetic models, we find a consistent inherent synthetic uncertainty of ∼10 K at a signal-to-noise ratio greater than 100. Additionally, we find that our results align with interferometric measurements, showing a consistent residual of −29 ± 31 K. Taking the inherent uncertainties into account, we infer the T eff values of our targets and find an excellent agreement with previous optical and near-infrared studies. Our high-resolution chemical analysis examines hundreds of absorption lines using χ 2 minimization using PHOENIX-ACES stellar atmosphere models. We present elemental abundances for up to 10 different elements, including refractory elements such as Si, Mg, and Fe, which are important for modeling the interior structure of exoplanets. In binary systems, we find an average [Fe/H] of −0.15 ± 0.08 for M dwarfs, marginally lower than the reported metallicity of −0.06 ± 0.18 for the FGK primaries from A. W. Mann et al. We also observe slightly subsolar chemistry for various elements in our nonbinary M dwarfs, most notably for O, C, and K abundances. In particular, we find an average metallicity of −0.11 ± 0.16, lower but still consistent with the typical solar metallicity of FGK stars (e.g., [Fe/H] = 0.04 ± 0.20 from J. M. Brewer et al. 2016). This study highlights significant discrepancies in various major M dwarf surveys likely related to differences in the methodologies employed.}, archive = {J_ApJ}, author = {Farbod Jahandar and René Doyon and Étienne Artigau and Neil J. Cook and Charles Cadieux and Jean-François Donati and Nicolas B. Cowan and Ryan Cloutier and Stefan Pelletier and Alan Alves-Brito and Jorge H. C. Martins and Hsien Shang and Andrés Carmona}, doi = {10.3847/1538-4357/ad91a0}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {154}, shortjournal = {The Astrophys. J.}, title = {Chemical fingerprints of m dwarfs: High-resolution spectroscopy on 31 m dwarfs with SPIRou}, volume = {978}, year = {2025}, }
• (2025). No need to know: Toward astrophysics-free gravitational-wave cosmology. ApJ, 978(2), 153. (www)

  @article{ , abstract = {Gravitational waves (GWs) from merging compact objects encode direct information about the luminosity distance to the binary. When paired with a redshift measurement, this enables standard-siren cosmology: a Hubble diagram can be constructed to directly probe the Universe's expansion. This can be done in the absence of electromagnetic measurements, as features in the mass distribution of GW sources provide self-calibrating redshift measurements without the need for a definite or probabilistic host galaxy association. This "spectral siren" technique has thus far only been applied with simple parametric representations of the mass distribution, and theoretical predictions for features in the mass distribution are commonly presumed to be fundamental to the measurement. However, the use of an inaccurate representation leads to biases in the cosmological inference, an acute problem given the current uncertainties in true source population. Furthermore, it is commonly presumed that the form of the mass distribution must be known a priori to obtain unbiased measurements of cosmological parameters in this fashion. Here, we demonstrate that spectral sirens can accurately infer cosmological parameters without such prior assumptions. We apply a flexible, nonparametric model for the mass distribution of compact binaries to a simulated catalog of 1000 GW signals, consistent with expectations for the next LIGO–Virgo–KAGRA observing run. We find that, despite our model's flexibility, both the source mass model and cosmological parameters are correctly reconstructed. We predict a 11.2% ✎ measurement of H 0 , keeping all other cosmological parameters fixed, and a 6.4% ✎ measurement of H ( z = 0.9) ✎ when fitting for multiple cosmological parameters (1 σ uncertainties). This astrophysically agnostic spectral siren technique will be essential to arrive at precise and unbiased cosmological constraints from GW source populations.}, archive = {J_ApJ}, author = {Amanda M. Farah and Thomas A. Callister and Jose María Ezquiaga and Michael Zevin and Daniel E. Holz}, doi = {10.3847/1538-4357/ad9253}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {153}, shortjournal = {The Astrophys. J.}, title = {No need to know: Toward astrophysics-free gravitational-wave cosmology}, volume = {978}, year = {2025}, }
• (2025). The rapid formation of the metal-poor milky way. ApJ, 978(2), 152. (www)

  @article{ , abstract = {Our understanding of the assembly timeline of the Milky Way has been transforming along with the dramatic increase in astrometric and spectroscopic data available over the past several years. Many substructures in chemo-dynamical space have been discovered and identified as the remnants of various galactic mergers. To investigate the timeline of these mergers, we select main-sequence turnoff and subgiant stars (MSTOs) from the H3 survey, finding members in seven metal-poor components of the halo: Gaia-Sausage/Enceladus (GSE), the Helmi Streams, Thamnos, Sequoia, Wukong/LMS-1, Arjuna, and I'itoi. We also select out a metal-poor in situ population to facilitate comparison to the evolution of the Milky Way itself at these early epochs. We fit individual isochrone ages to the MSTOs in each of these substructures and use the resulting age distributions to infer simple star formation histories (SFHs). For GSE, we resolve an extended SFH that truncates ≈10 Gyr ago, as well as a clear age–metallicity relation. From this age distribution and measured SFH we infer that GSE merged with the Milky Way at a time 9.5–10.2 Gyr ago, in agreement with previous estimates. We infer that the other mergers occurred at various times ranging from 9 to 13 Gyr ago, and that the metal-poor in situ Galaxy built up within only a few billion years. These results reinforce the emerging picture that both the disk and halo of the Milky Way experienced a rapid assembly.}, archive = {J_ApJ}, author = {Turner Woody and Charlie Conroy and Phillip Cargile and Ana Bonaca and Vedant Chandra and Jiwon Jesse Han and Benjamin D. Johnson and Rohan P. Naidu and Yuan-Sen Ting}, doi = {10.3847/1538-4357/ad968e}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {152}, shortjournal = {The Astrophys. J.}, title = {The rapid formation of the metal-poor milky way}, volume = {978}, year = {2025}, }
• (2025). YOLOX-LS: Strong gravitational lenses detection in the DECaLS with deep learning. ApJ, 978(2), 151. (www)

  @article{ , abstract = {The identification of strong gravitational lenses is essential to facilitate many studies in astronomy. The search for strong gravitational lenses has become more challenging because of their scientific value and their rarity. In this paper, we construct a data set for strong gravitational lensing searches that consist of known lenses and lens candidates from the Dark Energy Spectroscopic Instrument Legacy Imaging Surveys (the DESI Legacy Imaging Surveys) and the Dark Energy Survey (DES) and non-lenses from the Legacy Surveys Data Release 9 (DR9). We apply the YOLOX algorithm as the basic framework and improve it by selecting the optimal optimizer, activation function, attention mechanism, and loss function. The improved YOLOX-LS algorithm achieves 97.87%, 97.51%, 0.97, 96.8%, and 53.1% in the evaluation metrics of precision, recall, F1 score, mean average precision (mAP)@0.5, and mAP@0.5:0.95, respectively. Compared with the YOLOX model, it improves by 0.63%, 0.26%, and 0.6% in the three metrics of precision, recall, and mAP@0.5, respectively. This paper presents the results of the trained YOLOX-LS algorithm applied to 4.75 million cutout images. These images are centered on the central source with mag z ≤ 20 in the Dark Energy Camera Legacy Survey footprint from DESI DR9. Finally, we find 1697 lenses, including 303 known lenses or candidates, and 1394 new candidates, among which there are 102 high-quality candidates. This further verifies that the YOLOX-LS algorithm proposed in this paper can be effectively applied to the search for strong gravitational lenses. All visual results are displayed online at https://github.com/Young-mmm/YOLOX-LS .}, archive = {J_ApJ}, author = {Yangyang Liu and Liangping Tu and Jianxi Li and Jiawei Miao and Gengqi Lin and Chenying Zhao}, doi = {10.3847/1538-4357/ad97ba}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {151}, shortjournal = {The Astrophys. J.}, title = {YOLOX-LS: Strong gravitational lenses detection in the DECaLS with deep learning}, volume = {978}, year = {2025}, }
• (2025). Derivation and application of a scaling between Hinode/SP and SDO/HMI vector magnetic fields to improve magnetic field extrapolations. ApJ, 978(2), 150. (www)

  @article{ , abstract = {Full-disk measurements of the solar magnetic field by the Helioseismic and Magnetic Imager (HMI) are often used for magnetic field extrapolations, but its limited spatial and spectral resolution can lead to significant errors. We compare HMI data with observations of NOAA 12104 by the Hinode Spectropolarimeter (SP) to derive a scaling curve for the magnetic field strength, B . The SP data in the Fe i lines at 630 nm were inverted with the SIR code. We find that the Milne–Eddington inversion of HMI underestimates B and the line-of-sight flux, Φ, in all granulation surroundings by an average factor of 4.5 in plage and 9.2 in the quiet Sun in comparison to the SP. The deviation is inversely proportional to the magnetic fill factor, f , in the SP results. We derived a correction curve to match the HMI B with the effective flux B f in the SP data that scaled HMI B up by 1.3 on average. A comparison of non-force-free field extrapolations over a larger field of view without and with the correction revealed minor changes in connectivity and a proportional scaling of electric currents and Lorentz force (∝ B ∼ 1.3) and free energy (∝ B 2 ∼ 2). Magnetic field extrapolations of HMI vector data with large areas of plage and quiet Sun will underestimate the photospheric magnetic field strength by a factor of 5–10 and the coronal magnetic flux by at least a factor of 2. An HMI inversion including a fill factor would mitigate the problem.}, archive = {J_ApJ}, author = {C. Beck and A. Prasad and Q. Hu and M. S. Yalim and S. Gosain and D. Prasad Choudhary}, doi = {10.3847/1538-4357/ad98e6}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {150}, shortjournal = {The Astrophys. J.}, title = {Derivation and application of a scaling between Hinode/SP and SDO/HMI vector magnetic fields to improve magnetic field extrapolations}, volume = {978}, year = {2025}, }
• (2025). Hot spot offset variability from magnetohydrodynamical thermoresistive instability in hot jupiters. ApJ, 978(2), 149. (www)

  @article{ , abstract = {Hot Jupiter (HJ) atmospheres are possibly subject to a thermoresistive instability (TRI). Such an instability may develop as the ohmic heating increases the electrical conductivity in a positive feedback loop, which ultimately leads to a runaway of the atmospheric temperature. We extend our previous axisymmetric one-dimensional radial model, by representing the temperature and magnetic diffusivity as a first-order Fourier expansion in longitude. This allows us to predict the hot spot offset during the rapid unfolding of the TRI and following Alfvénic oscillations. The instability is periodically triggered and damped within ≈10–40 days, depending on the magnetic field strength, with months of slow buildup between recurring bursts. We show a few representative simulations undergoing TRI, in which the peak flux offset varies between approximately ±60 ∘ on a timescale of a few days with potentially observable brightness variations. Therefore, this TRI could be an observable feature of HJs, given the right timing of observation and transit and the right planetary parameters.}, archive = {J_ApJ}, author = {Raphaël Hardy and Paul Charbonneau and Andrew Cumming}, doi = {10.3847/1538-4357/ad9902}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {149}, shortjournal = {The Astrophys. J.}, title = {Hot spot offset variability from magnetohydrodynamical thermoresistive instability in hot jupiters}, volume = {978}, year = {2025}, }
• (2025). Strongly magnetized accretion with low angular momentum produces a weak jet. ApJ, 978(2), 148. (www)

  @article{ , abstract = {We study the spherical accretion of magnetized plasma with low angular momentum onto a supermassive black hole, utilizing global general relativistic magnetohydrodynamic simulations. Black hole-driven feedback in the form of magnetic eruptions and jets triggers magnetized turbulence in the surrounding medium. We find that when the Bondi radius exceeds a certain value relative to the black hole's gravitational radius, this turbulence restricts the subsequent inflow of magnetic flux, strongly suppressing the strength of the jet. Consequently, magnetically arrested disks and powerful jets are not a generic outcome of the accretion of magnetized plasma, even if there is an abundance of magnetic flux available in the system. However, if there is significant angular momentum in the inflowing gas, the eruption-driven turbulence is suppressed (sheared out), allowing for the presence of a powerful jet. Both the initially rotating and nonrotating flows go through periods of low and high gas angular momentum, showing that the angular momentum content of the inflowing gas is not just a feature of the ambient medium, but is strongly modified by the eruption and jet-driven black hole feedback. In the lower-angular-momentum states, our results predict that there should be dynamically strong magnetic fields on horizon scales, but no powerful jet; this state may be consistent with Sgr A* in the Galactic center.}, archive = {J_ApJ}, author = {Alisa Galishnikova and Alexander Philippov and Eliot Quataert and Koushik Chatterjee and Matthew Liska}, doi = {10.3847/1538-4357/ad9926}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {148}, shortjournal = {The Astrophys. J.}, title = {Strongly magnetized accretion with low angular momentum produces a weak jet}, volume = {978}, year = {2025}, }
• (2025). Latitude quenching nonlinearity in the solar dynamo. ApJ, 978(2), 147. (www)

  @article{ , abstract = {We compare two candidate nonlinearities for regulating the solar cycle within the Babcock–Leighton paradigm: tilt quenching (whereby the tilt of active regions is reduced in stronger cycles) and latitude quenching (whereby flux emerges at higher latitudes in stronger solar cycles). Digitized historical observations are used to build a database of individual magnetic plage regions from 1923 to 1985. The regions are selected by thresholding in Ca ii K synoptic maps, with polarities constrained using Mount Wilson Observatory sunspot measurements. The resulting data show weak evidence for tilt quenching, but much stronger evidence for latitude quenching. Further, we use proxy observations of the polar field from faculae to construct a best-fit surface flux transport model driven by our database of emerging regions. A better fit is obtained when the sunspot measurements are used, compared to a reference model where all polarities are filled using Hale's Law. The optimization suggests clearly that the "dynamo effectivity range" of the Sun during this period should be less than 10°; this is also consistent with latitude quenching being dominant over tilt quenching.}, archive = {J_ApJ}, author = {Anthony R. Yeates and Luca Bertello and Alexander A. Pevtsov and Alexei A. Pevtsov}, doi = {10.3847/1538-4357/ad99d0}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {147}, shortjournal = {The Astrophys. J.}, title = {Latitude quenching nonlinearity in the solar dynamo}, volume = {978}, year = {2025}, }
• (2025). Can alfvénic fluctuations affect the correlation and complexity of magnetic field of magnetic ejecta? a case study based on multi-spacecraft measurements at 1 au. ApJ, 978(2), 146. (www)

  @article{ , abstract = {We investigate whether Alfvénic fluctuations (AFs) can affect the structure of magnetic ejecta (ME) within interplanetary coronal mass ejections (ICMEs). We study an ICME observed on 2001 December 29 at 1 au by the Advanced Composition Explorer (ACE) and Wind, at a total angular separation of ~0 \mathop{.}\limits^{\unicode{x000b0}} 8 (~ 0.014 au). We focus on the correlation and complexity of its magnetic structure measured between two spacecraft in association with large-amplitude AFs. The Alfvénicity of the ME is investigated in terms of the residual energy and cross helicity of fluctuations. We find that as for the event of interest, large-amplitude AFs occur in the rear region of the ME at both Wind and ACE with a duration of about 6 hr. We compare the correlation of the magnetic field strength and vector components measured between Wind and ACE, and investigate complexity in terms of the magnetic hodograms. The region showing AFs is found to be associated with a decreased correlation of the magnetic field components and an increased complexity of the ME magnetic configuration detected at ACE and Wind, which may be due to the fact that the two spacecraft crossing the same ME along different trajectories likely sampled AFs in different oscillation phases. Combining multipoint in situ measurements and remote-sensing observations of the ICME source region, we further discuss different potential sources of the AFs.}, archive = {J_ApJ}, author = {Camilla Scolini and Bin Zhuang and Noé Lugaz and Réka M. Winslow and Charles J. Farrugia and Norbert Magyar and Fabio Bacchini}, doi = {10.3847/1538-4357/ad9a55}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {146}, shortjournal = {The Astrophys. J.}, title = {Can alfvénic fluctuations affect the correlation and complexity of magnetic field of magnetic ejecta? a case study based on multi-spacecraft measurements at 1 au}, volume = {978}, year = {2025}, }
• (2025). Prospects for observing high-redshift radio-loud quasars in the SKA era: Paving the way for 21 cm forest observations. ApJ, 978(2), 145. (www)

  @article{ , abstract = {The 21 cm forest is a sensitive probe for the early heating process and small-scale structures during the epoch of reionization (EOR), to be realized with the upcoming Square Kilometre Array (SKA). Its detection relies on the availability of radio-bright background sources, among which the radio-loud quasars are very promising, but their abundance during the EOR is still poorly constrained due to limited observations. In this work, we use a physics-driven model to forecast future radio-loud quasar observations. We fit the parameters of the model using observational data of high-redshift quasars. Assuming Eddington accretion, the model yields an average lifetime of t q ~ 10 5.5 yr for quasars at z ~ 6, consistent with recent results obtained from quasar proximity zone observation. We show that if the radio-loud fraction of quasars evolves with redshift, it will significantly reduce the abundance of observable radio-loud quasars in the SKA era, making 21 cm forest studies challenging. With a constant radio-loud fraction, our model suggests that a 1 yr sky survey conducted with SKA-LOW has the capability to detect approximately 20 radio-loud quasars at z ~ 9, with sufficient sensitivity to resolve individual 21 cm forest lines.}, archive = {J_ApJ}, author = {Qi Niu and Yichao Li and Yidong Xu and Hong Guo and Xin Zhang}, doi = {10.3847/1538-4357/ad9b97}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {145}, shortjournal = {The Astrophys. J.}, title = {Prospects for observing high-redshift radio-loud quasars in the SKA era: Paving the way for 21 cm forest observations}, volume = {978}, year = {2025}, }
• (2025). A catalog of stellar and dust properties for 500,000 stars in the southwest bar of the small magellanic cloud. ApJ, 978(2), 144. (www)

  @article{ , abstract = {We present a catalog of individual stellar and dust extinction properties along close to 500,000 sight lines in the southwest bar of the Small Magellanic Cloud (SMC). The catalog is based on multiband Hubble Space Telescope photometric data spanning near-ultraviolet to near-infrared wavelengths from the Small Magellanic Cloud Investigation of Dust and Gas Evolution survey (SMIDGE) covering a 100 × 200 pc area. We use the probabilistic technique of the Bayesian Extinction And Stellar Tool (BEAST) to model the spectral energy distributions of individual stars in SMIDGE and include the effects of observational uncertainties in the data. We compare BEAST-derived dust extinction properties with tracers of the interstellar medium, such as the emission from the 12 CO (2–1) transition ( I (CO)), the dust mass surface density (Σ dust ) from far-IR emission, the H i column density ( N (H i )) from the 21 cm transition, and the mass fraction of polycyclic aromatic hydrocarbons (PAHs; q PAH , derived from IR emission). We find that the dust extinction ( A ( V )) in the SMIDGE field is strongly correlated with Σ dust and I (CO), and less so with N (H i ) and q PAH , and suggest potential explanations. Our extinction measurements are also sensitive to the presence of the 2175 Å bump in the extinction curve toward UV bright stars. While most do not show evidence for the bump, we identify ∼200 lines of sight that are 2175 Å bump candidates. Furthermore, we find distinct structures in the dust extinction–distance distributions that provide insights into the 3D geometry of the SMC.}, archive = {J_ApJ}, author = {Petia Yanchulova Merica-Jones and Karl Gordon and Karin Sandstrom and Claire E. Murray and L. Clifton Johnson and Julianne J. Dalcanton and Julia Roman-Duval and Jeremy Chastenet and Benjamin F. Williams and Daniel R. Weisz and Andrew E. Dolphin}, doi = {10.3847/1538-4357/ad8eb7}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {144}, shortjournal = {The Astrophys. J.}, title = {A catalog of stellar and dust properties for 500,000 stars in the southwest bar of the small magellanic cloud}, volume = {978}, year = {2025}, }
• (2025). Modeling energetic proton transport from a stream interaction region to compound streams. ApJ, 978(2), 143. (www)

  @article{ , abstract = {Energetic proton events associated with a stream interaction region (SIR) were observed by two Solar-Terrestrial Relations Observatory (STEREO) and WIND spacecraft from 2007 September 19 to September 25. Different from the measurements of STEREO-A and WIND, the observational data of STEREO-B show additional particle intensity increases when the spacecraft is immersed into the compound stream region with poor compression signatures after the passage of the SIR. In order to investigate this particular event, we simulated proton transport with a solar wind pattern obtained from the two-dimensional analytical model driven by plasma and magnetic field data of the spacecraft. We find that the additional energetic proton event is not an autonomous event created by the compound streams and is closely associated with the accelerated particles in the preceding SIR structure. We highlight the variation in particle distribution as a function of radial distance within the SIR. The magnetic field configuration in the compound stream region observed by STEREO-B provides a more direct connection to the source particle region, which presents a view to explain the differences between the energetic proton observations of the three spacecraft.}, archive = {J_ApJ}, author = {Xinyi Tao and Fang Shen and Xi Luo}, doi = {10.3847/1538-4357/ad96ae}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {143}, shortjournal = {The Astrophys. J.}, title = {Modeling energetic proton transport from a stream interaction region to compound streams}, volume = {978}, year = {2025}, }
• (2025). Extreme solar particle ejection event in the last few million years from asteroid itokawa sample. ApJ, 978(2), 142. (www)

  @article{ , abstract = {Unusual explosive activity occasionally occurs from the Sun, releasing large amounts of solar energetic particles. Extreme solar particle ejection events in the past 11,000 yr have been detected by sharp increases of cosmogenic isotopes in annual tree rings and ice cores. However, quantitative estimation of the event magnitudes is not straightforward, as the cosmogenic isotopes are indirect records of solar particles. Similar solar particle ejection events may also accumulate records in surface materials of airless bodies such as the Moon and asteroids. Samples from the asteroid 25143 Itokawa have been irradiated by solar winds for tens to hundreds of years at some points in the last few million years. Here, we report implantation profiles of solar particle He from an Itokawa regolith grain that trace an extreme solar particle ejection event. The implantation profiles indicate that the fluences of suprathermal solar particles were 250–1300 times larger than that expected from the current normal solar activity. Since the degrees of excesses are inversely related to the solar wind irradiation periods, the high-energy particle fluence would have been derived from a single event. The event was approximately 40 times larger than the 2003 Halloween solar storms, which is one of the largest solar particle ejection events observed since the space-based measurement of solar activity began. The event magnitude is similar to the largest events inferred from the cosmogenic isotope records in terrestrial samples. Our result provides direct evidence of an extreme solar particle ejection event in the last few million years.}, archive = {J_ApJ}, author = {Tomoya Obase and Ken-ichi Bajo and Yuta Otsuki and Hisayoshi Yurimoto}, doi = {10.3847/1538-4357/ad9919}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {142}, shortjournal = {The Astrophys. J.}, title = {Extreme solar particle ejection event in the last few million years from asteroid itokawa sample}, volume = {978}, year = {2025}, }
• (2025). Observed steep and shallow spectra, narrow and broadband spectra, multifrequency simultaneous spectra, and statistical fringe spectra in fast radio bursts: Various faces of intrinsic quasi-periodic spectra?. ApJ, 978(2), 141. (www)

  @article{ , abstract = {Through analysis, modelings, and simulations, we show that if the spectra of fast radio bursts (FRBs) are intrinsically quasi-periodic, and likely produced by coherent curvature radiation from quasi-periodic structured bunches, then the observed steep and shallow spectra, narrow and broadband spectra, multifrequency simultaneous spectra, as well as possible statistical fringe spectra in FRBs, could all be various manifestations of them. If so, the period properties of the structured bunches, as inferred from the observed multifrequency simultaneous spectra and potential statistical fringe spectra, may provide valuable insights into the mechanisms behind the formation of such structured bunches.}, archive = {J_ApJ}, author = {Shu-Qing Zhong and Wen-Jin Xie and Jia-Hong Gu}, doi = {10.3847/1538-4357/ad98f8}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {141}, shortjournal = {The Astrophys. J.}, title = {Observed steep and shallow spectra, narrow and broadband spectra, multifrequency simultaneous spectra, and statistical fringe spectra in fast radio bursts: Various faces of intrinsic quasi-periodic spectra?}, volume = {978}, year = {2025}, }
• (2025). Detection of a magnetic discontinuity in the upper solar chromosphere associated with a coronal loop brightening observed by CLASP2.1. ApJ, 978(2), 140. (www)

  @article{ , abstract = {We report the first detection of a magnetic discontinuity in the upper solar chromosphere associated with a coronal loop brightening. Our findings are based on novel observations obtained by the Chromospheric LAyer SpectroPolarimeter (CLASP2.1) suborbital space experiment. During its short 6 minute flight, CLASP2.1 successfully obtained spectropolarimetric data across the Mg ii h and k lines, which allowed us to map the longitudinal magnetic field at multiple heights in the chromosphere of a solar active region. During our observation, we found a coronal loop brightening that was intermittently and recurrently heated. The temperature of the brightening plasma is above 2.5 MK, which is higher than the ambient temperature, and no corresponding brightening is detected in the images of the photosphere and lower chromosphere. The notable finding of our study is that the coronal loop brightening of interest is observed across a region where the magnetic field polarity changes abruptly in the upper chromosphere. Our results provide observational evidence that the heating mechanism of the coronal loop brightening is consistent with magnetic reconnection in the upper solar chromosphere.}, archive = {J_ApJ}, author = {Donguk Song and Ryohko Ishikawa and David E. McKenzie and Javier Trujillo Bueno and Frédéric Auchère and Ryouhei Kano and Amy Winebarger and Takenori J. Okamoto and Laurel A. Rachmeler and Ken Kobayashi and Genevieve D. Vigil and Adam R. Kobelski and Christian Bethge and Eun-Kyung Lim and Luca Belluzzi and Ernest Alsina Ballester and Tanausú del Pino Alemán and Jiří Štěpán}, doi = {10.3847/1538-4357/ad94f6}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {140}, shortjournal = {The Astrophys. J.}, title = {Detection of a magnetic discontinuity in the upper solar chromosphere associated with a coronal loop brightening observed by CLASP2.1}, volume = {978}, year = {2025}, }
• (2025). Orbit of a possible planet x. ApJ, 978(2), 139. (www)

  @article{ , abstract = {The plausibility of an unseen planet in the outer solar system, and the expected orbit and mass of such a planet, have long been a topic of inquiry and debate. We calculate the long-term orbital stability of distant trans-Neptunian objects (TNOs), which allows us to expand the sample of objects that would carry dynamical information about a hypothetical unseen planet in the solar system. Using this expanded sample, we find statistically significant clustering at the ∼3 σ level for TNOs with semimajor axes > 170 au in the longitude of perihelion ( ϖ ), but not in inclination ( i ), argument of perihelion ( ω ), or longitude of node (Ω). Since a natural explanation for clustering in ϖ is an unseen planet, we run 300 N -body simulations with the giant planets, a disk of test particles representing Kuiper Belt objects, and an additional planet with varied initial conditions for its mass, semimajor axis, eccentricity, and inclination. Based on the distribution of test particles after 1–2 Gyr, we compute relative likelihoods given the actual distribution of ϖ as a function of semimajor axis for distant TNOs on stable orbits using a significantly larger sample than previous work. We find the best-fit unseen planet parameters to have mass m p = 4.4 ± 1.1 M ⊕ , semimajor axis a p = 290 ± 30 au, eccentricity e p = 0.29 ± 0.13, and inclination i p = 6 \mathop{.}\limits^{\unicode{x000b0}} 8 ± 5 \mathop{.}\limits^{\unicode{x000b0}} 0. Only 0.06% of the M. E. Brown & K. Batygin Planet Nine reference population produce probabilities within 1 σ of the maximum within our quadrivariate model, indicating that our work identifies a distinct preferred region of parameter space for an unseen planet in the solar system.}, archive = {J_ApJ}, author = {Amir Siraj and Christopher F. Chyba and Scott Tremaine}, doi = {10.3847/1538-4357/ad98f6}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {139}, shortjournal = {The Astrophys. J.}, title = {Orbit of a possible planet x}, volume = {978}, year = {2025}, }
• (2025). Radio follow-up observations of SN 2023ixf by japanese and korean very long baseline interferometers. ApJ, 978(2), 138. (www)

  @article{ , abstract = {We report on radio follow-up observations of the nearby Type II supernova SN 2023ixf, spanning from 1.7 to 269.9 days after the explosion, conducted using three very long baseline interferometers (VLBIs), which are the Japanese VLBI Network, the VLBI Exploration of Radio Astrometry, and the Korean VLBI Network. In three observation epochs (152.3, 206.1, and 269.9 days), we detected emission at the 6.9 and 8.4 GHz bands, with a flux density of ~5 mJy. The flux density reached a peak at around 206.1 days, which is longer than the timescale to reach the peak observed in typical Type II supernovae. Based on an analytical model of radio emission, our late-time detections were inferred to be due to decreasing optical depth. In this case, the mass-loss rate of the progenitor is estimated to have increased from ~10 −6 –10 −5 M ⊙ yr −1 to ~10 −4 M ⊙ yr −1 between 28 and 6 yr before the explosion. Our radio constraints are also consistent with the mass-loss rate needed to produce a confined circumstellar medium proposed by previous studies, which suggest that the mass-loss rate increased from ~10 −4 M ⊙ yr −1 to ≳10 −2 M ⊙ yr −1 in the last few years before the explosion.}, archive = {J_ApJ}, author = {Yuhei Iwata and Masanori Akimoto and Tomoki Matsuoka and Keiichi Maeda and Yoshinori Yonekura and Nozomu Tominaga and Takashi J. Moriya and Kenta Fujisawa and Kotaro Niinuma and Sung-Chul Yoon and Jae-Joon Lee and Taehyun Jung and Do-Young Byun}, doi = {10.3847/1538-4357/ad9a62}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {138}, shortjournal = {The Astrophys. J.}, title = {Radio follow-up observations of SN 2023ixf by japanese and korean very long baseline interferometers}, volume = {978}, year = {2025}, }
• (2025). Automated detection of galactic rings from sloan digital sky survey images. ApJ, 978(2), 137. (www)

  @article{ , abstract = {Morphological features in galaxies—like spiral arms, bars, rings, and tidal tails, etc.—carry information about their structure, origin, and evolution. It is therefore important to catalog and study such features and to correlate them with other basic galaxy properties, the environments in which the galaxies are located, and their interactions with other galaxies. The volume of present and future data on galaxies is so large that traditional methods, which involve expert astronomers identifying morphological features through visual inspection, are no longer sufficient. It is therefore necessary to use AI-based techniques like machine learning and deep learning to find morphological structures quickly and efficiently. We report in this study the application of deep learning for finding ring-like structures in galaxy images from the Sloan Digital Sky Survey (SDSS) DR18. We use a catalog by R. J. Buta of ringed galaxies from SDSS to train the network, reaching good accuracy and recall, and generate a catalog of 29,420 galaxies, of which 4855 have ring-like structures with prediction confidence exceeding 90%. Using a catalog of barred galaxy images identified by S. Abraham et. al. with deep-learning techniques, we identify a set of 2087 galaxies with bars as well as rings. The catalog should be very useful in understanding the origin of these important morphological structures. As an example of the usefulness of the catalog, we explore the environments and star formation characteristics of the ring galaxies in our sample.}, archive = {J_ApJ}, author = {Linn Abraham and Sheelu Abraham and Ajit K. Kembhavi and N. S. Philip and A. K. Aniyan and Sudhanshu Barway and Harish Kumar}, doi = {10.3847/1538-4357/ad856d}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {137}, shortjournal = {The Astrophys. J.}, title = {Automated detection of galactic rings from sloan digital sky survey images}, volume = {978}, year = {2025}, }
• (2025). Unveiling the cosmic chemistry: Revisiting the Mass–Metallicity relation with JWST/NIRSpec at 4 < z < 10. ApJ, 978(2), 136. (www)

  @article{ , abstract = {We present star formation rates (SFRs), the mass–metallicity relation (MZR), and the SFR-dependent MZR across redshifts 4–10 using 81 star-forming galaxies observed by the JWST NIRSpec employing both low-resolution PRISM and medium-resolution gratings, including galaxies from the JWST Advanced Deep Extragalactic Survey (JADES) GOODS-N and GOODS-S fields, the JWST-PRIMAL Legacy Survey, and additional galaxies from the literature in the A2744, SMACS-0723, RXJ2129, BDF, COSMOS, and MACS1149 fields. These galaxies span a 3 dex stellar mass range of 10 7 < M * / M ⊙ < 10 10 , with an average SFR of 7.2 ± 1.2 M ⊙ yr −1 and an average metallicity of 12+\mathrm{log}({\rm{O}}/{\rm{H}})=7.91\pm 0.08 . Our findings align with previous observations up to z = 8 for the MZR and indicate no deviation from the local Universe fundamental metallicity relation (FMR) up to this redshift. Beyond z = 8, we observe a significant deviation (∼0.27 dex) in FMR, consistent with recent JWST findings. We also integrate Cosmic Evolution Early Release Science (135 galaxies) and JADES (47 galaxies) samples with our data to study the metallicity evolution with redshift in a combined sample of 263 galaxies, revealing a decreasing metallicity trend with a slope of 0.067 ± 0.013, consistent with IllustrisTNG and EAGLE but contradicting the FIRE simulations. We introduce an empirical mass–metallicity–redshift relation: 12+{\rm{log}}({\rm{O}}/{\rm{H}})=6.29+0.237 × \mathrm{log}({M}_{* }/{M}_{\odot })-0.06\times (1+z) , which accurately reproduces the observed trends in metallicity with both redshift and stellar mass. This trend underscores the "Grand Challenge" in understanding the factors driving high-redshift galactic metallicity trends, such as inflow, outflow, and active galactic nucleus/stellar feedback—and emphasizes the need for further investigations with larger samples and enhanced simulations.}, archive = {J_ApJ}, author = {Arnab Sarkar and Priyanka Chakraborty and Mark Vogelsberger and Michael McDonald and Paul Torrey and Alex M. Garcia and Gourav Khullar and Gary J. Ferland and William Forman and Scott Wolk and Benjamin Schneider and Mark Bautz and Eric Miller and Catherine Grant and John ZuHone}, doi = {10.3847/1538-4357/ad8f32}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {136}, shortjournal = {The Astrophys. J.}, title = {Unveiling the cosmic chemistry: Revisiting the Mass–Metallicity relation with JWST/NIRSpec at 4 < z < 10}, volume = {978}, year = {2025}, }
• (2025). PHANGS-ML: The universal relation between PAH band and optical line ratios across nearby star-forming galaxies. ApJ, 978(2), 135. (www)

  @article{ , abstract = {The structure and chemistry of the dusty interstellar medium (ISM) are shaped by complex processes that depend on the local radiation field, gas composition, and dust grain properties. Of particular importance are polycyclic aromatic hydrocarbons (PAHs), which emit strong vibrational bands in the mid-infrared, and play a key role in the ISM energy balance. We recently identified global correlations between PAH band and optical line ratios across three nearby galaxies, suggesting a connection between PAH heating and gas ionization throughout the ISM. In this work, we perform a census of the PAH heating–gas ionization connection using ∼700,000 independent pixels that probe scales of 40–150 pc in 19 nearby star-forming galaxies from the PHANGS survey. We find a universal relation between \mathrm{log} PAH(11.3 μ m/7.7 μ m) and \mathrm{log} ([S ii ]/H α ) with a slope of ∼0.2 and a scatter of ∼0.025 dex. The only exception is a group of anomalous pixels that show unusually high (11.3 μ m/7.7 μ m) PAH ratios in regions with old stellar populations and high starlight-to-dust emission ratios. Their mid-infrared spectra resemble those of elliptical galaxies. Active galactic nucleus hosts show modestly steeper slopes, with a ∼​​​​​​10% increase in PAH(11.3 μ m/7.7 μ m) in the diffuse gas on kiloparsec scales. This universal relation implies an emerging simplicity in the complex ISM, with a sequence that is driven by a single varying property: the spectral shape of the interstellar radiation field. This suggests that other properties, such as gas-phase abundances, gas ionization parameter, and grain charge distribution, are relatively uniform in all but specific cases.}, archive = {J_ApJ}, author = {Dalya Baron and Karin M. Sandstrom and Jessica Sutter and Hamid Hassani and Brent Groves and Adam K. Leroy and Eva Schinnerer and Médéric Boquien and Matilde Brazzini and Jérémy Chastenet and Daniel A. Dale and Oleg V. Egorov and Simon C. O. Glover and Ralf S. Klessen and Debosmita Pathak and Erik Rosolowsky and Frank Bigiel and Mélanie Chevance and Kathryn Grasha and Annie Hughes and J. Eduardo Méndez-Delgado and Jérôme Pety and Thomas G. Williams and Stephen Hannon and Sumit K. Sarbadhicary}, doi = {10.3847/1538-4357/ad972a}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {135}, shortjournal = {The Astrophys. J.}, title = {PHANGS-ML: The universal relation between PAH band and optical line ratios across nearby star-forming galaxies}, volume = {978}, year = {2025}, }
• (2025). Emission characteristics of energetic electrons with crescent-shaped velocity distributions. ApJ, 978(2), 134. (www)

  @article{ , abstract = {Solar flares release magnetic energy through reconnection, accelerating electrons into nonthermal velocity distributions, including crescent-shaped electron populations. These energetic electron distributions are crucial in driving instabilities that can lead to distinct electromagnetic emissions. This study investigates the emission properties of crescent-shaped electron velocity distribution functions under different frequency ratios ( ω pe /Ω ce ), critical for understanding plasma conditions in various astrophysical environments, by comparing the emissions and intensities of waves among different cases. Here, we study and analyze three distinct frequency ratio conditions (2.2, 10, and 1, designated as cases A, B, and C, respectively). We find that the beam-Langmuir and upper-hybrid modes can be efficiently excited, leading to further plasma emissions in different cases. Our study reveals that the fundamental (O/F) emission can reach a maximum value of ∼10 −4 E k0 , while the harmonics (H) can extend to ∼1.5 × 10 −5 E k0 , depending on the frequency ratio of the environment. The intensity of the fundamental mode exceeds previous findings for pure-ring, pure-beam, and ring–beam distributions, highlighting the impact of crescent-shaped electron velocity distributions on wave excitation and emission processes. This effect is notably influenced by different frequency ratios, offering new insights into the way that nonthermal electron distributions affect the plasma emission process.}, archive = {J_ApJ}, author = {Mehdi Yousefzadeh}, doi = {10.3847/1538-4357/ad9905}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {134}, shortjournal = {The Astrophys. J.}, title = {Emission characteristics of energetic electrons with crescent-shaped velocity distributions}, volume = {978}, year = {2025}, }
• (2025). Shock breakouts from compact circumstellar medium surrounding core-collapse supernova progenitors may contribute significantly to the observed ≳10 TeV neutrino background. ApJ, 978(2), 133. (www)

  @article{ , abstract = {Growing observational evidence suggests that enhanced mass loss from the progenitors of core-collapse supernovae (SNe) is common during  ~1 yr preceding the explosion, creating an optically thick circumstellar medium (CSM) shell at  ~10 14.5 cm radii. We show that if such mass loss is indeed common, then the breakout of the SN shock through the dense CSM shell produces a neutrino flux that may account for a significant fraction of the observed  ≳10 TeV neutrino background. The neutrinos are created within a few days from the explosion, during and shortly after the shock breakout, which produces also large UV (and later X-ray) luminosity. The compact size and large UV luminosity imply a pair production optical depth of  ~10 4 for  > 100 GeV photons, naturally accounting for the lack of a high-energy gamma-ray background accompanying the neutrino background. SNe producing  >1 neutrino event in a 1 km 2 detector are expected at a rate of  ≲0.1 yr −1 . A quantitative theory describing the evolution of the electromagnetic spectrum during a breakout, as the radiation-mediated shock is transformed into a collisionless one, is required to enable (i) using data from upcoming surveys that will systematically detect large numbers of young,  <1 day old SNe to determine the preexplosion mass-loss history of the SN progenitor population, and (ii) a quantitative determination of the neutrino luminosity and spectrum.}, archive = {J_ApJ}, author = {Eli Waxman and Tal Wasserman and Eran O. Ofek and Avishay Gal-Yam}, doi = {10.3847/1538-4357/ad9a6b}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {133}, shortjournal = {The Astrophys. J.}, title = {Shock breakouts from compact circumstellar medium surrounding core-collapse supernova progenitors may contribute significantly to the observed ≳10 TeV neutrino background}, volume = {978}, year = {2025}, }
• (2025). In search of extraterrestrial artificial intelligence through dyson sphere–like structures around primordial black holes. ApJ, 978(2), 132. (www)

  @article{ , abstract = {Are we alone? It is a compelling question that human beings have confronted for centuries. The search for extraterrestrial life is a broad range of quests for finding simple forms of life up to intelligent beings in the Universe. The plausible assumption is that there is a chance that intelligent life will be followed by advanced civilization equipped or even dominated by artificial intelligence (AI). In this work, we categorize advanced civilizations (on an equal footing, an AI-dominated civilization) on the Kardashev scale. We propose a new scale known as the space exploration distance to measure civilization advancement. We propose a relation between this length and the Kardashev scale. Then, we suggest the idea that advanced civilizations will use primordial black holes (PBHs) as sources of harvesting energy. We calculate the energy harvested by calculating the space exploration distance. Finally, we propose an observational method to detect the possibility of extraterrestrial AI using Dyson sphere–like structures around PBHs in the Milky Way and other galaxies.}, archive = {J_ApJ}, author = {Shant Baghram}, doi = {10.3847/1538-4357/ad9b10}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {132}, shortjournal = {The Astrophys. J.}, title = {In search of extraterrestrial artificial intelligence through dyson sphere–like structures around primordial black holes}, volume = {978}, year = {2025}, }
• (2025). Ejective feedback as a quenching mechanism in the first 1.5 billion years of the universe: Detection of neutral gas outflow in a z = 4 recently quenched galaxy. ApJ, 978(2), 131. (www)

  @article{ , abstract = {The confirmation of massive quiescent galaxies emerging within the first billion years of the Universe poses intriguing questions about the mechanisms of galaxy formation. There must be highly efficient processes at work to shut down star formation in galaxies at cosmic dawn. I present the detection of neutral outflowing gas in a massive recently quenched galaxy at z = 4, showing ejective back as a quenching mechanism. Based on James Webb Space Telescope spectrum, the star formation rate (SFR) of this has been declining with a rapid e -folding timescale of ∼50 Myr. The current specific SFR is 5 × 10 −11 yr −1 , roughly 40 times lower than that of the star-forming main sequence at comparable redshifts. Emission-line ratios of [Ne iii ]/[O ii ] and [O iii ]/H β are similar to active galactic nuclei (AGNs) at comparable redshifts. A series of Fe ii and Mg ii absorption lines appear blueshifted by ∼250 km s −1 relative to the stellar continuum, suggesting an outflow of neutral gas. The estimated mass outflow rate is approximately 7 times greater than the SFR derived from the stellar continuum, implying that the suppression of star formation is likely due to gas being depleted by the outflow. If the emission lines are AGN-driven, the AGN can also provide sufficient energy to launch the outflow observed. This galaxy represents the most distant example of its kind known to date. This study offers a compelling explanation for the existence of massive quiescent galaxies in the first billion years of the Universe.}, archive = {J_ApJ}, author = {Po-Feng Wu}, doi = {10.3847/1538-4357/ad98ef}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {131}, shortjournal = {The Astrophys. J.}, title = {Ejective feedback as a quenching mechanism in the first 1.5 billion years of the universe: Detection of neutral gas outflow in a z = 4 recently quenched galaxy}, volume = {978}, year = {2025}, }
• (2025). Analysis of polarized dust emission using data from the first flight of SPIDER. ApJ, 978(2), 130. (www)

  @article{ , abstract = {Using data from the first flight of Spider and from the Planck High Frequency Instrument, we probe the properties of polarized emission from interstellar dust in the Spider observing region. Component-separation algorithms operating in both the spatial and harmonic domains are applied to probe their consistency and to quantify modeling errors associated with their assumptions. Analyses of diffuse Galactic dust emission spanning the full Spider region demonstrate (i) a spectral energy distribution that is broadly consistent with a modified-blackbody (MBB) model with a spectral index of β d = 1.45 ± 0.05 (1.47 ± 0.06) for E ( B )-mode polarization, slightly lower than that reported by Planck for the full sky; (ii) an angular power spectrum broadly consistent with a power law; and (iii) no significant detection of line-of-sight polarization decorrelation. Tests of several modeling uncertainties find only a modest impact (∼10% in σ r ) on Spider 's sensitivity to the cosmological tensor-to-scalar ratio. The size of the Spider region further allows for a statistically meaningful analysis of the variation in foreground properties within it. Assuming a fixed dust temperature T d = 19.6 K, an analysis of two independent subregions of that field results in inferred values of β d = 1.52 ± 0.06 and β d = 1.09 ± 0.09, which are inconsistent at the 3.9 σ level. Furthermore, a joint analysis of Spider and Planck 217 and 353 GHz data within one subregion is inconsistent with a simple MBB at more than 3 σ , assuming a common morphology of polarized dust emission over the full range of frequencies. This evidence of variation may inform the component-separation approaches of future cosmic microwave background polarization experiments.}, archive = {J_ApJ}, author = {P. A. R. Ade and M. Amiri and S. J. Benton and A. S. Bergman and R. Bihary and J. J. Bock and J. R. Bond and J. A. Bonetti and S. A. Bryan and H. C. Chiang and C. R. Contaldi and O. Doré and A. J. Duivenvoorden and H. K. Eriksen and J. P. Filippini and A. A. Fraisse and K. Freese and M. Galloway and A. E. Gambrel and N. N. Gandilo and K. Ganga and S. Gourapura and R. Gualtieri and J. E. Gudmundsson and M. Halpern and J. Hartley and M. Hasselfield and G. Hilton and W. Holmes and V. V. Hristov and Z. Huang and K. D. Irwin and W. C. Jones and A. Karakci and C. L. Kuo and Z. D. Kermish and J. S.-Y. Leung and S. Li and D. S. Y. Mak and P. V. Mason and K. Megerian and L. Moncelsi and T. A. Morford and J. M. Nagy and C. B. Netterfield and M. Nolta and R. O’Brient and B. Osherson and I. L. Padilla and B. Racine and A. S. Rahlin and C. Reintsema and J. E. Ruhl and M. C. Runyan and T. M. Ruud and J. A. Shariff and E. C. Shaw and C. Shiu and J. D. Soler and X. Song and A. Trangsrud and C. Tucker and R. S. Tucker and A. D. Turner and J. F. van der List and A. C. Weber and I. K. Wehus and D. V. Wiebe and E. Y. Young and Spider Collaboration}, doi = {10.3847/1538-4357/ad900c}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {130}, shortjournal = {The Astrophys. J.}, title = {Analysis of polarized dust emission using data from the first flight of SPIDER}, volume = {978}, year = {2025}, }
• (2025). EDGE-INFERNO: Simulating every observable star in faint dwarf galaxies and their consequences for resolved-star photometric surveys. ApJ, 978(2), 129. (www)

  @article{ , abstract = {Interpretation of data from faint dwarf galaxies is made challenging by observations limited to only the brightest stars. We present a major improvement to tackle this challenge by undertaking zoomed cosmological simulations that resolve the evolution of all individual stars more massive than 0.5 M ⊙ , thereby explicitly tracking all observable stars for the Hubble time. For the first time, we predict observable color–magnitude diagrams and the spatial distribution of ≈100,000 stars within four faint ( M ⋆ ≈ 10 5 M ⊙ ) dwarf galaxies directly from their cosmological initial conditions. In all cases, simulations predict complex light profiles with multiple components, implying that typical observational measures of structural parameters can make the total V -band magnitudes appear up to 0.5 mag dimmer compared to estimates from simulations. Furthermore, when only small (⪅100) numbers of stars are observable, shot noise from realizations of the color–magnitude diagram introduces uncertainties comparable to the population scatter in, e.g., the total magnitude, half-light radius, and mean iron abundance measurements. Estimating these uncertainties with fully self-consistent mass growth, star formation, and chemical enrichment histories paves the way for more robust interpretation of dwarf galaxy data.}, archive = {J_ApJ}, author = {Eric P. Andersson and Martin P. Rey and Andrew Pontzen and Corentin Cadiou and Oscar Agertz and Justin I. Read and Nicolas F. Martin}, doi = {10.3847/1538-4357/ad99d6}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {129}, shortjournal = {The Astrophys. J.}, title = {EDGE-INFERNO: Simulating every observable star in faint dwarf galaxies and their consequences for resolved-star photometric surveys}, volume = {978}, year = {2025}, }
• (2025). Identifying the coronal holes in open magnetic field regions using deep learning. ApJ, 978(2), 128. (www)

  @article{ , abstract = {Open magnetic field (OMF) regions are the foot points of the field lines extending to infinity. While they are often considered to coincide with coronal holes (CHs), many studies have reported non-negligible inconsistency between the two. The objective of this study is to develop a deep learning model to predict the OMF regions that coincide with CHs, and to examine the importance of different physical quantities on the prediction. The CHs and OMF regions are both identified from the coronal data computed by a magnetohydrodynamic model developed by Predictive Science. Eight physical quantities, colatitude, magnetic flux expansion factor, magnetic field strength, thermal pressure, electron temperature, electron number density, mass density, and local coronal heating rate, at the OMF footpoints are used as the input to the deep learning model. The results of the test set indicate that the model improves the consistency between CHs and OMF regions from 0.33 to 0.81, and that all eight quantities are similarly important when they are all included in the model although the prediction accuracy would be most affected by excluding the colatitude and/or magnetic field strength. Comparison between the histograms of CH and non-CH open field regions indicates that each quantity alone can be used to distinguish the two within the ranges of values where one histogram is much higher than the other.}, archive = {J_ApJ}, author = {Guan-Han Huang and Chia-Hsien Lin}, doi = {10.3847/1538-4357/ad9a54}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {128}, shortjournal = {The Astrophys. J.}, title = {Identifying the coronal holes in open magnetic field regions using deep learning}, volume = {978}, year = {2025}, }
• (2025). Understanding the radio emission from the β cep star v2187 cyg. ApJ, 978(2), 127. (www)

  @article{ , abstract = {We analyze the radio emission from the β Cep star V2187 Cyg using archive data from the Jansky Very Large Array. The observations were made in ten epochs at 1.39 and 4.96 GHz in the highest angular resolution A configuration. We determine a spectral index of of α = 0.6 ± 0.2 ( S ν ∝ ν α ), consistent with an ionized wind or a partially optically thick synchrotron or gyrosynchrotron source. The emission is spatially unresolved at both frequencies. The 4.96 GHz data show a radio pulse with a duration of about one month that can be modeled in terms of an internal shock in the stellar wind produced by a sudden increase in the mass-loss rate and the terminal velocity. The quiescent radio emission of V2187 Cyg at 4.96 GHz (with a flux density of  ≃150 μ Jy) cannot be explained in terms of an internally (by V2187 Cyg) or externally (by a nearby O star) photoionized wind. We conclude that, despite the spectral index suggestive of free–free emission from an ionized wind, the radio emission of V2187 Cyg most likely has a magnetic origin, a possibility that can be tested with a sensitive search for circular polarization in the radio, as expected from gyrosynchrotron radiation and also by trying to measure the stellar magnetic field, which is expected to be in the range of several kilogauss.}, archive = {J_ApJ}, author = {Luis F. Rodríguez and Susana Lizano and Jorge Cantó and Ricardo F. González and Mauricio Tapia}, doi = {10.3847/1538-4357/ad9a69}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {127}, shortjournal = {The Astrophys. J.}, title = {Understanding the radio emission from the β cep star v2187 cyg}, volume = {978}, year = {2025}, }
• (2025). Mass transfer in eccentric black Hole–Neutron star mergers. ApJ, 978(2), 126. (www)

  @article{ , abstract = {Black hole–neutron star binaries are of interest in many ways: they are intrinsically transient, radiate gravitational waves detectable by LIGO, and may produce γ -ray bursts. Although it has long been assumed that their late-stage orbital evolution is driven entirely by gravitational wave emission, we show here that in certain circumstances, mass transfer from the neutron star onto the black hole can both alter the binary's orbital evolution and significantly reduce the neutron star's mass: when the fraction of its mass transferred per orbit is ≳10 −2 , the neutron star's mass diminishes by order unity, leading to mergers in which the neutron star mass is exceptionally small. The mass transfer creates a gas disk around the black hole before merger that can be comparable in mass to the debris remaining after merger, i.e., ~0.1 M ⊙ . These processes are most important when the initial neutron star–black hole mass ratio q is in the range ≈0.2–0.8, the orbital semimajor axis is 40 ≲ a 0 / r g ≲ 300 ( r g ≡ GM BH / c 2 ), and the eccentricity is large at e 0 ≳ 0.8. Systems of this sort may be generated through the dynamical evolution of a triple system, as well as by other means.}, archive = {J_ApJ}, author = {Yossef Zenati and Mor Rozner and Julian H. Krolik and Elias R. Most}, doi = {10.3847/1538-4357/ad9b87}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {126}, shortjournal = {The Astrophys. J.}, title = {Mass transfer in eccentric black Hole–Neutron star mergers}, volume = {978}, year = {2025}, }
• (2025). Observational evidence for a correlation between the magnetic field of jets and star formation rate in host galaxies. ApJ, 978(2), 125. (www)

  @article{ , abstract = {Accretion supermassive black holes in the center of active galaxies usually produce "jet"-collimated bipolar outflows of relativistic particles. Magnetic fields near the black hole event horizon may play a crucial role in the formation of jets/outflows. Both theory and observation indicate that jets/outflows driven by centrally active supermassive black holes have a feedback effect on the overall properties of the host galaxies. Therefore, the magnetic field is a key ingredient for the formation and evolution of galaxies. Here, we report a clear correlation between the magnetic field of jets and star formation rate for a large sample of 96 galaxies hosting supermassive black holes, which suggests that the star formation of active galactic nuclei host galaxies may be powered by the jets.}, archive = {J_ApJ}, author = {Yongyun Chen and Qiusheng Gu and Junhui Fan and Xiaotong Guo and Xiaoling Yu and Nan Ding and Dingrong Xiong}, doi = {10.3847/1538-4357/ad9b8a}, journal = {The Astrophysical Journal}, month = {1}, number = {2}, pages = {125}, shortjournal = {The Astrophys. J.}, title = {Observational evidence for a correlation between the magnetic field of jets and star formation rate in host galaxies}, volume = {978}, year = {2025}, }